A lithium-ion or Li-ion battery is a type of
rechargeable battery
A rechargeable battery, storage battery, or secondary cell (formally a type of Accumulator (energy), energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to ...
which uses the reversible
reduction of
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
s to store energy. It is the predominant battery type used in portable
consumer electronics
Consumer electronics or home electronics are electronic (analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usually r ...
and
electric vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s. It also sees significant use for
grid-scale energy storage and military and
aerospace
Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...
applications. Compared to other rechargeable battery technologies, Li-ion batteries have high
energy densities
In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or .
Often only the ''useful'' or extract ...
, low
self-discharge
Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes or any external circuit. Self-discharge decreases the shelf life
Shelf life ...
, and no
memory effect
Memory effect, also known as battery effect, lazy battery effect, or battery memory, is an effect observed in nickel-cadmium rechargeable batteries that causes them to hold less charge. It describes the situation in which nickel-cadmium batter ...
(although a small memory effect reported in
LFP cells has been traced to poorly made cells).
Chemistry, performance, cost and safety characteristics vary across types of lithium-ion batteries. Most commercial Li-ion cells use
intercalation compounds as the active materials. The anode or negative electrode is usually
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
, although
silicon-carbon is also being increasingly used. Cells can be manufactured to prioritize either energy or power density. Handheld electronics mostly use
lithium polymer batteries
A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electro ...
(with a polymer gel as electrolyte), a
lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
() cathode material, and a
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
anode, which together offer a high energy density.
Lithium iron phosphate
Lithium iron phosphate or lithium ferro-phosphate (LFP) is an inorganic compound with the formula . It is a gray, red-grey, brown or black solid that is insoluble in water. The material has attracted attention as a component of lithium iron phosp ...
(),
lithium manganese oxide ( spinel, or -based lithium rich layered materials, LMR-NMC), and
lithium nickel manganese cobalt oxide Lithium nickel manganese cobalt oxides (abbreviated Li-NMC, LNMC, or NMC) are mixed metal oxides of lithium, nickel, manganese and cobalt. They have the general formula LiNi''x''Mn''y''Co''z''O2. The most important representatives have a composition ...
( or NMC) may offer longer lives and may have better rate capability. NMC and its derivatives are widely used in the
electrification of transport
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
, one of the main technologies (combined with
renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
) for reducing
greenhouse gas emissions from vehicles.
M. Stanley Whittingham
Michael Stanley Whittingham (born 22 December 1941) is a British-American chemist. He is currently a professor of chemistry and director of both the Institute for Materials Research and the Materials Science and Engineering program at Binghamton ...
discovered the concept of
intercalation electrodes in the 1970s and created the first rechargeable lithium-ion battery, which was based on a
titanium disulfide
Titanium disulfide is an inorganic compound with the formula Ti S2. A golden yellow solid with high electrical conductivity, it belongs to a group of compounds called transition metal dichalcogenides, which consist of the stoichiometry M E2. ...
cathode and a lithium-aluminum anode, although it suffered from safety issues and was never commercialized.
John Goodenough
John Bannister Goodenough ( ; born July 25, 1922) is an American materials scientist, a solid-state physicist, and a Nobel laureate in chemistry. He is a professor of Mechanical, Materials Science, and Electrical Engineering at the University ...
expanded on this work in 1980 by using
lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
as a cathode.
The first prototype of the modern Li-ion battery, which uses a carbonaceous anode rather than lithium metal, was developed by
Akira Yoshino
is a Japanese chemist. He is a fellow of Asahi Kasei Corporation and a professor at Meijo University in Nagoya. He created the first safe, production-viable lithium-ion battery which became used widely in cellular phones and notebook computers ...
in 1985, which was commercialized by a
Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...
and
Asahi Kasei
is a multinational Japanese chemical company. Its main products are chemicals and materials science.
It was founded in May 1931, using the paid in capital of Nobeoka Ammonia Fiber Co., Ltd, a Nobeoka, Miyazaki based producer of ammonia, nit ...
team led by Yoshio Nishi in 1991.
Lithium-ion batteries can be a safety hazard if not properly engineered and manufactured since cells have flammable electrolytes and if damaged or incorrectly charged, can lead to explosions and fires. Much development has made progress in manufacturing safe Lithium-ion batteries. Lithium Ion All
Solid State Batteries are being developed to eliminate the flammable electrolyte. Improperly
recycled batteries can create toxic waste, especially from toxic metals and are at risk of fire. Moreover, both
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
and other key strategic minerals used in batteries have significant issues at extraction, with lithium being water intensive in often arid regions and other minerals often being
conflict minerals
The eastern Democratic Republic of the Congo (DRC) has a history of conflict, where various armies, rebel groups, and outside actors have profited from mining while contributing to violence and exploitation during wars in the region. The four mai ...
such as
cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...
. Both
environmental issues
Environmental issues are effects of human activity on the biophysical environment, most often of which are harmful effects that cause environmental degradation. Environmental protection is the practice of protecting the natural environment on t ...
have encouraged some researchers to improve mineral efficiency and alternatives such as
iron-air batteries.
Research areas for lithium-ion batteries include extending lifetime, increasing energy density, improving safety, reducing cost, and increasing charging speed, among others. Research has been under way in the area of non-flammable electrolytes as a pathway to increased safety based on the flammability and volatility of the organic solvents used in the typical electrolyte. Strategies include
aqueous lithium-ion batteries, ceramic solid electrolytes, polymer electrolytes, ionic liquids, and heavily fluorinated systems.
History
Research on rechargeable Li-ion batteries dates to the 1960s; one of the earliest examples is a /Li battery developed by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
in 1965. The breakthrough that produced the earliest form of the modern Li-ion battery was made by British chemist
M. Stanley Whittingham
Michael Stanley Whittingham (born 22 December 1941) is a British-American chemist. He is currently a professor of chemistry and director of both the Institute for Materials Research and the Materials Science and Engineering program at Binghamton ...
in 1974, who first used
titanium disulfide
Titanium disulfide is an inorganic compound with the formula Ti S2. A golden yellow solid with high electrical conductivity, it belongs to a group of compounds called transition metal dichalcogenides, which consist of the stoichiometry M E2. ...
() as a cathode material, which has a layered structure that can
take in lithium ions without significant changes to its
crystal structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...
.
Exxon
ExxonMobil Corporation (commonly shortened to Exxon) is an American multinational oil and gas corporation headquartered in Irving, Texas. It is the largest direct descendant of John D. Rockefeller's Standard Oil, and was formed on November 30, ...
tried to commercialize this battery in the late 1970s, but found the synthesis expensive and complex, as is sensitive to moisture and releases toxic gas on contact with water. More prohibitively, the batteries were also prone to spontaneously catch fire due to the presence of metallic lithium in the cells. For this, and other reasons, Exxon discontinued development of Whittingham's lithium-titanium disulfide battery.
In 1980 working in separate groups Ned A. Godshall et al., and, shortly thereafter,
Koichi Mizushima
is a Japanese former gymnast who competed in the 1988 Summer Olympics
The 1988 Summer Olympics (), officially known as the Games of the XXIV Olympiad () and commonly known as Seoul 1988 ( ko, 서울 1988, Seoul Cheon gubaek palsip-p ...
and
John B. Goodenough, after testing a range of alternative materials, replaced with
lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
(, or LCO), which has a similar layered structure but offers a higher voltage and is much more stable in air. This material would later be used in the first commercial Li-ion battery, although it did not, on its own, resolve the persistent issue of flammability.
The same year,
Rachid Yazami demonstrated the reversible electrochemical intercalation of lithium in graphite, and invented the lithium graphite electrode (anode).
These early attempts to develop rechargeable Li-ion batteries used lithium metal anodes, which were ultimately abandoned due to safety concerns, as lithium metal is unstable and prone to
dendrite
Dendrites (from Greek δένδρον ''déndron'', "tree"), also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the n ...
formation, which can cause
short-circuiting. The eventual solution was to use an intercalation anode, similar to that used for the cathode, which prevents the formation of lithium metal during battery charging. A variety of anode materials were studied; in 1987,
Akira Yoshino
is a Japanese chemist. He is a fellow of Asahi Kasei Corporation and a professor at Meijo University in Nagoya. He created the first safe, production-viable lithium-ion battery which became used widely in cellular phones and notebook computers ...
patented what would become the first commercial lithium-ion battery using an anode of "
soft carbon" (a charcoal-like material) along with Goodenough's previously reported LCO cathode and a
carbonate ester
In organic chemistry, a carbonate ester (organic carbonate or organocarbonate) is an ester of carbonic acid. This functional group consists of a carbonyl group flanked by two alkoxy groups. The general structure of these carbonates is and they ...
-based electrolyte. In 1991, using Yoshino's design,
Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...
began producing and selling the world's first rechargeable lithium-ion batteries. The following year, a
joint venture
A joint venture (JV) is a business entity created by two or more parties, generally characterized by shared ownership, shared returns and risks, and shared governance. Companies typically pursue joint ventures for one of four reasons: to acces ...
between
Toshiba
, commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure system ...
and
Asashi Kasei Co. also released their lithium-ion battery.
Significant improvements in energy density were achieved in the 1990s by replacing the soft carbon anode first with hard carbon and later with graphite, a concept originally proposed by
Jürgen Otto Besenhard
Jürgen or Jurgen is a popular masculine given name in Germany, Estonia, Belgium and the Netherlands. It is cognate with George. Notable people named Jürgen include:
A
*Jürgen Ahrend (born 1930), German organ builder
*Jürgen Alzen (born 19 ...
in 1974 but considered unfeasible due to unresolved incompatibilities with the electrolytes then in use.
In 2012 John B. Goodenough, Rachid Yazami and Akira Yoshino received the 2012 IEEE Medal for Environmental and Safety Technologies for developing the lithium-ion battery; Goodenough, Whittingham, and Yoshino were awarded the 2019
Nobel Prize in Chemistry
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then "M ...
"for the development of lithium-ion batteries".
In 2010, global lithium-ion battery production capacity was 20 gigawatt-hours. By 2016, it was 28 GWh, with 16.4 GWh in China. Global production capacity was 767 GWh in 2020, with China accounting for 75%. Production in 2021 is estimated by various sources to be between 200 and 600 GWh, and predictions for 2023 range from 400 to 1,100 GWh.
Design
![Liion-18650-AA-battery](https://upload.wikimedia.org/wikipedia/commons/2/2a/Liion-18650-AA-battery.jpg)
Generally, the negative electrode of a conventional lithium-ion cell is
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
made from
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
. The positive electrode is typically a metal
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
. The
electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
is a
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
in an
organic solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
. The
anode
An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
(negative electrode) and
cathode
A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in whi ...
(positive electrode) are prevented from shorting by a separator. The anode and cathode are separated from external electronics with a piece of metal called a current collector.
The electrochemical roles of the electrodes reverse between anode and cathode, depending on the direction of current flow through the cell.
The most common commercially used anode is
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
, which in its fully lithiated state of LiC
6 correlates to a maximal capacity of 1339 C/g (372 mAh/g).
[G. Shao et al.: Polymer-Derived SiOC Integrated with a Graphene Aerogel As a Highly Stable Li-Ion Battery Anode](_blank)
ACS Appl. Mater. Interfaces 2020, 12, 41, 46045–46056 The cathode is generally one of three materials: a layered
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
(such as
lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
), a
polyanion
Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are t ...
(such as
lithium iron phosphate
Lithium iron phosphate or lithium ferro-phosphate (LFP) is an inorganic compound with the formula . It is a gray, red-grey, brown or black solid that is insoluble in water. The material has attracted attention as a component of lithium iron phosp ...
) or a
spinel
Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals.
Properties
S ...
(such as lithium
manganese oxide Manganese oxide is any of a variety of manganese oxides and hydroxides.Wells A.F. (1984) ''Structural inorganic chemistry'' 5th edition Oxford Science Publications, . These include
* Manganese(II) oxide, MnO
* Manganese(II,III) oxide, Mn3O4
* Man ...
). More experimental materials include
graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. -containing electrodes, although these remain far from commercially viable due to their high cost.
Lithium reacts vigorously with water to form
lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It can exist as anhydrous or hydrated, and both forms are white hygroscopic solids. They are soluble in water and slightly soluble in ethanol. Both are available commercially. While ...
(LiOH) and
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes moisture from the battery pack. The non-aqueous electrolyte is typically a mixture of organic carbonates such as
ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...
and
propylene carbonate
Propylene carbonate (often abbreviated PC) is an organic compound with the formula C4H6O3. It is a cyclic carbonate ester derived from propylene glycol. This colorless and odorless liquid is useful as a polar, aprotic solvent. Propylene carbo ...
containing
complexes of lithium ions.
Ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...
is essential for making
solid electrolyte interphase
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
on the carbon anode, but since it is solid at room temperature, a
propylene carbonate
Propylene carbonate (often abbreviated PC) is an organic compound with the formula C4H6O3. It is a cyclic carbonate ester derived from propylene glycol. This colorless and odorless liquid is useful as a polar, aprotic solvent. Propylene carbo ...
solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
is added.
The electrolyte salt is almost always
lithium hexafluorophosphate
Lithium hexafluorophosphate is an inorganic compound with the formula Li PF6. It is a white crystalline powder.
Production
LiPF6 is manufactured by reacting phosphorus pentachloride with hydrogen fluoride and lithium fluoride
:PCl5 + LiF + 5 ...
(), which combines good
ionic conductivity with chemical and electrochemical stability.
Hexafluorophosphate
Hexafluorophosphate is an anion with chemical formula of . It is an octahedral species that imparts no color to its salts. is isoelectronic with sulfur hexafluoride, , and the hexafluorosilicate dianion, , and hexafluoroantimonate . In this anio ...
is essential for passivating the aluminum current collector used for the cathode. A titanium tab is ultrasonically
welded
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as braz ...
to the aluminum current collector.
Other salts like
lithium perchlorate
Lithium perchlorate is the inorganic compound with the formula LiClO4. This white or colourless crystalline salt is noteworthy for its high solubility in many solvents. It exists both in anhydrous form and as a trihydrate.
Applications Inorga ...
(),
lithium tetrafluoroborate
Lithium tetrafluoroborate is an inorganic compound with the formula Li BF4. It is a white crystalline powder. It has been extensively tested for use in commercial secondary batteries, an application that exploits its high solubility in nonpolar ...
(), and
lithium bis(trifluoromethanesulfonyl)imide
Lithium bis(trifluoromethanesulfonyl)imide, often simply referred to as LiTFSI, is a hydrophilic salt with the chemical formula LiC2F6NO4S2. It is commonly used as Li-ion source in electrolytes for Li-ion batteries as a safer alternative to common ...
() are frequently used in research in tab-less
coin cells, but are not usable in larger format cells, often because they are not compatible with the aluminum current collector. Copper (with a spot-welded
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
tab) is used as the anode current collector.
Current collector design and surface treatments may take various forms: foil, mesh, foam (dealloyed), etched (wholly or selectively), and coated (with various materials) to improve electrical characteristics.
Depending on materials choices, the
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
,
energy density
In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or .
Often only the ''useful'' or extract ...
, life, and safety of a lithium-ion cell can change dramatically. Current effort has been exploring the use of
novel architectures using
nanotechnology
Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal o ...
to improve performance. Areas of interest include nano-scale electrode materials and alternative electrode structures.
The increasing demand for batteries has led vendors and academics to focus on improving the energy density,
operating temperature
An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...
, safety, durability, charging time, output power, elimination of cobalt requirements, and cost of lithium-ion battery technology.
Electrochemistry
The reactants in the electrochemical reactions in a lithium-ion cell are materials of anode and cathode, both of which are compounds containing lithium atoms. During discharge, an oxidation
half-reaction
A half reaction (or half-cell reaction) is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction. ...
at the anode produces positively charged lithium ions and negatively charged electrons. The oxidation half-reaction may also produce uncharged material that remains at the anode. Lithium ions move through the electrolyte, electrons move through the external circuit, and then they recombine at the cathode (together with the cathode material) in a reduction half-reaction. The electrolyte and external circuit provide conductive media for lithium ions and electrons, respectively, but do not partake in the electrochemical reaction. During discharge, electrons flow from the negative electrode (anode) towards the positive electrode (cathode) through the external circuit. The reactions during discharge lower the chemical potential of the cell, so discharging transfers
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
from the cell to wherever the electric current dissipates its energy, mostly in the external circuit. During charging these reactions and transports go in the opposite direction: electrons move from the positive electrode to the negative electrode through the external circuit. To charge the cell the external circuit has to provide electric energy. This energy is then stored as chemical energy in the cell (with some loss, e. g. due to
coulombic efficiency Faraday efficiency (also called ''faradaic efficiency'', ''faradaic yield'', ''coulombic efficiency'' or ''current efficiency'') describes the efficiency with which charge (electrons) is transferred in a system facilitating an electrochemical reacti ...
lower than 1).
Both electrodes allow lithium ions to move in and out of their structures with a process called ''insertion'' (''
intercalation'') or ''extraction'' (''deintercalation''), respectively.
As the lithium ions "rock" back and forth between the two electrodes, these batteries are also known as "rocking-chair batteries" or "swing batteries" (a term given by some European industries).
The following equations exemplify the chemistry.
The positive electrode (cathode) half-reaction in the lithium-doped cobalt oxide substrate is
:
CoO2 + Li+ + e- <=> LiCoO2
The negative electrode (anode) half-reaction for the graphite is
:
LiC6 <=> C6 + Li+ + e^-
The full reaction (left to right: discharging, right to left: charging) being
:
LiC6 + CoO2 <=> C6 + LiCoO2
The overall reaction has its limits. Overdischarging supersaturates
lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
, leading to the production of
lithium oxide
Lithium oxide ( O) or lithia is an inorganic chemical compound. It is a white solid. Although not specifically important, many materials are assessed on the basis of their Li2O content. For example, the Li2O content of the principal lithium miner ...
, possibly by the following irreversible reaction:
:
Li+ + e^- + LiCoO2 -> Li2O + CoO
Overcharging up to 5.2
volts
The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827).
Defini ...
leads to the synthesis of cobalt (IV) oxide, as evidenced by
x-ray diffraction
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
:
:
LiCoO2 -> Li+ + CoO2 + e^-
In a lithium-ion cell, the lithium ions are transported to and from the positive or negative electrodes by oxidizing the
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...
, cobalt (
Co), in from to during charge, and reducing from to during discharge. The cobalt electrode reaction is ''only'' reversible for ''x'' < 0.5 (''x'' in
mole units), limiting the depth of discharge allowable. This chemistry was used in the Li-ion cells developed by Sony in 1990.
The cell's energy is equal to the voltage times the charge. Each gram of lithium represents
Faraday's constant
In physical chemistry, the Faraday constant, denoted by the symbol and sometimes stylized as ℱ, is the electric charge per mole of elementary charges. It is named after the English scientist Michael Faraday. Since the 2019 redefinition of ...
/6.941, or 13,901 coulombs. At 3 V, this gives 41.7 kJ per gram of lithium, or 11.6 kWh per kilogram of lithium. This is a bit more than the heat of combustion of
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
but does not consider the other materials that go into a lithium battery and that make lithium batteries many times heavier per unit of energy.
The cell voltages given in the Electrochemistry section are larger than the potential at which
aqueous solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be re ...
s will
electrolyze
In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...
.
Liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
electrolytes in lithium-ion batteries consist of lithium
salts
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...
, such as
,
or
in an
organic solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
, such as
ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...
,
dimethyl carbonate
Dimethyl carbonate (DMC) is an organic compound with the formula OC(OCH3)2. It is a colourless, flammable liquid. It is classified as a carbonate ester. This compound has found use as a methylating agent and more recently as a solvent that is ...
, and
diethyl carbonate
Diethyl carbonate (sometimes abbreviated DEC) is an ester of carbonic acid and ethanol with the formula OC(OCH2CH3)2. At room temperature (25 °C) diethyl carbonate is a colorless liquid with a low flash point.
Diethyl carbonate is used as ...
. A liquid electrolyte acts as a conductive pathway for the movement of cations passing from the negative to the positive electrodes during discharge. Typical conductivities of liquid electrolyte at room temperature () are in the range of 10
mS/cm, increasing by approximately 30–40% at and decreasing slightly at . The combination of linear and cyclic carbonates (e.g.,
ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...
(EC) and
dimethyl carbonate
Dimethyl carbonate (DMC) is an organic compound with the formula OC(OCH3)2. It is a colourless, flammable liquid. It is classified as a carbonate ester. This compound has found use as a methylating agent and more recently as a solvent that is ...
(DMC)) offers high conductivity and
solid electrolyte interphase
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
(SEI)-forming ability. Organic solvents easily decompose on the negative electrodes during charge. When appropriate
organic solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...
s are used as the electrolyte, the solvent decomposes on initial charging and forms a solid layer called the solid electrolyte interphase, which is electrically insulating, yet provides significant ionic conductivity. The interphase prevents further decomposition of the electrolyte after the second charge. For example,
ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...
is decomposed at a relatively high voltage, 0.7 V vs. lithium, and forms a dense and stable interface. Composite electrolytes based on POE (poly(oxyethylene)) provide a relatively stable interface. It can be either solid (high molecular weight) and be applied in dry Li-polymer cells, or liquid (low molecular weight) and be applied in regular Li-ion cells.
Room-temperature ionic liquids (RTILs) are another approach to limiting the flammability and volatility of organic electrolytes.
Recent advances in battery technology involve using a solid as the electrolyte material. The most promising of these are ceramics. Solid ceramic electrolytes are mostly lithium metal
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
s, which allow lithium-ion transport through the solid more readily due to the intrinsic lithium. The main benefit of solid electrolytes is that there is no risk of leaks, which is a serious safety issue for batteries with liquid electrolytes. Solid ceramic electrolytes can be further broken down into two main categories: ceramic and glassy.
Ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
solid electrolytes are highly ordered compounds with
crystal structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...
s that usually have ion transport channels. Common ceramic electrolytes are lithium
super ion conductors (LISICON) and
perovskites
A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mou ...
.
Glass
Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
y solid electrolytes are
amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek ''a'' ("wi ...
atomic structures made up of similar elements to ceramic solid electrolytes but have higher
conductivities overall due to higher conductivity at grain boundaries. Both glassy and ceramic electrolytes can be made more ionically conductive by substituting sulfur for oxygen. The larger radius of sulfur and its higher ability to be
polarized allow higher conductivity of lithium. This contributes to conductivities of solid electrolytes are nearing parity with their liquid counterparts, with most on the order of 0.1 mS/cm and the best at 10 mS/cm. An efficient and economic way to tune targeted electrolytes properties is by adding a third component in small concentrations, known as an additive. By adding the additive in small amounts, the bulk properties of the electrolyte system will not be affected whilst the targeted property can be significantly improved. The numerous additives that have been tested can be divided into the following three distinct categories: (1) those used for SEI chemistry modifications; (2) those used for enhancing the ion conduction properties; (3) those used for improving the safety of the cell (e.g. prevent overcharging).
Charging and discharging
During discharge, lithium ions () carry the
current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
within the battery cell from the negative to the positive electrode, through the non-
aqueous
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be rep ...
electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
and separator diaphragm.
[Linden, David and Reddy, Thomas B. (eds.) (2002). ''Handbook of Batteries 3rd Edition''. McGraw-Hill, New York. chapter 35. .]
During charging, an external electrical power source (the charging circuit) applies an over-voltage (a higher voltage than the battery produces, of the same polarity), forcing a charging current to flow within each cell from the positive to the negative electrode, i.e., in the reverse direction of a discharge current under normal conditions. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as
intercalation.
Energy losses arising from electrical
contact resistance
The term contact resistance refers to the contribution to the total resistance of a system which can be attributed to the contacting interfaces of electrical leads and connections as opposed to the intrinsic resistance. This effect is describe ...
at interfaces between
electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials de ...
layers and at contacts with current collectors can be as high as 20% of the entire energy flow of batteries under typical operating conditions.
The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different:
* A single Li-ion cell is charged in two stages:
#
Constant current A constant current (steady current, time-independent current, stationary current) is a type of direct current (DC) that does not change its intensity with time.
Sources
If the load is constant, a steady current can be obtained via a constant vo ...
(CC)
#
Constant voltage (CV)
* A Li-ion battery (a set of Li-ion cells in series) is charged in three stages:
#
Constant current A constant current (steady current, time-independent current, stationary current) is a type of direct current (DC) that does not change its intensity with time.
Sources
If the load is constant, a steady current can be obtained via a constant vo ...
# Balance (only required when cell groups become unbalanced during use)
#
Constant voltage
During the ''constant current'' phase, the charger applies a constant current to the battery at a steadily increasing voltage, until the top-of-charge voltage limit per cell is reached.
During the ''balance'' phase, the charger/battery reduces the charging current (or cycles the charging on and off to reduce the average current) while the
state of charge
State of charge (SoC) is the level of charge of an electric battery relative to its capacity. The units of SoC are percentage points (0% = empty; 100% = full). An alternative form of the same measure is the depth of discharge (DoD), the inverse ...
of individual cells is brought to the same level by a balancing circuit, until the battery is balanced. Balancing typically occurs whenever one or more cells reach their top-of-charge voltage before the other(s), as it is generally inaccurate to do so at other stages of the charge cycle. This is most commonly done by passive balancing, which dissipates excess charge via resistors connected momentarily across the cell(s) to be balanced. Active balancing is less common, more expensive, but more efficient, returning excess energy to other cells (or the entire pack) through the means of a
DC-DC converter
A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) ...
or other circuitry. Some fast chargers skip this stage. Some chargers accomplish the balance by charging each cell independently. This is often performed by the
battery protection circuit/
battery management system (BPC or BMS) and not the charger (which typically provides only the bulk charge current, and does not interact with the pack at the cell-group level), e.g.,
e-bike
An electric bicycle (e-bike, eBike, etc.) is a motorized bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fall into two broad categories: bikes that assist ...
and
hoverboard
A hoverboard (or hover board) is a levitating board used for personal transportation, first described in science-fiction, and made famous by the appearance of a skateboard-like hoverboard in the film '' Back to the Future Part II''. Many attemp ...
chargers. In this method, the BPC/BMS will request a lower charge current (such as EV batteries), or will shut-off the charging input (typical in portable electronics) through the use of
transistor
upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...
circuitry while balancing is in effect (to prevent over-charging cells). Balancing most often occurs during the constant voltage stage of charging, switching between charge modes until complete. The pack is usually fully-charged only when balancing is complete, as even a single cell group lower in charge than the rest will limit the entire battery's usable capacity to that of its own. Balancing can last hours or even days, depending on the magnitude of imbalance in the battery.
During the ''constant voltage'' phase, the charger applies a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines towards 0, until the current is below a set threshold of about 3% of initial constant charge current.
Periodic topping charge about once per 500 hours. Top charging is recommended to be initiated when voltage goes below
Failure to follow current and voltage limitations can result in an explosion.
Charging temperature limits for Li-ion are stricter than the operating limits. Lithium-ion chemistry performs well at elevated temperatures but prolonged exposure to heat reduces battery life. Li‑ion batteries offer good charging performance at cooler temperatures and may even allow "fast-charging" within a temperature range of .
Charging should be performed within this temperature range. At temperatures from 0 to 5 °C charging is possible, but the charge current should be reduced. During a low-temperature charge, the slight temperature rise above ambient due to the internal cell resistance is beneficial. High temperatures during charging may lead to battery degradation and charging at temperatures above 45 °C will degrade battery performance, whereas at lower temperatures the internal resistance of the battery may increase, resulting in slower charging and thus longer charging times.
Consumer-grade lithium-ion batteries should not be charged at temperatures below . Although a battery pack may appear to be charging normally, electroplating of metallic lithium can occur at the negative electrode during a subfreezing charge, and may not be removable even by repeated cycling. Most devices equipped with Li-ion batteries do not allow charging outside of 0–45 °C for safety reasons, except for mobile phones that may allow some degree of charging when they detect an emergency call in progress.
![Li ion laptop battery](https://upload.wikimedia.org/wikipedia/commons/1/1a/Li_ion_laptop_battery.jpg)
Batteries gradually self-discharge even if not connected and delivering current. Li-ion rechargeable batteries have a
self-discharge
Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes or any external circuit. Self-discharge decreases the shelf life
Shelf life ...
rate typically stated by manufacturers to be 1.5–2% per month.
The rate increases with temperature and state of charge. A 2004 study found that for most cycling conditions self-discharge was primarily time-dependent; however, after several months of stand on open circuit or float charge, state-of-charge dependent losses became significant. The self-discharge rate did not increase monotonically with state-of-charge, but dropped somewhat at intermediate states of charge. Self-discharge rates may increase as batteries age.
In 1999, self-discharge per month was measured at 8% at 21 °C, 15% at 40 °C, 31% at 60 °C. By 2007, monthly self-discharge rate was estimated at 2% to 3%,
[Battery performance characteristics]
MPower UK, 23 February 2007. Information on self-discharge characteristics of battery types. and 2
–3% by 2016.
By comparison, the self-discharge rate for
NiMH batteries dropped, as of 2017, from up to 30% per month for previously common cells
to about 0.08–0.33% per month for
low self-discharge NiMH batteries, and is about 10% per month in
NiCd batteries.
Cathode
Cathode materials are generally constructed from or . The cobalt-based material develops a pseudo tetrahedral structure that allows for two-dimensional lithium-ion diffusion.
The cobalt-based cathodes are ideal due to their high theoretical specific heat capacity, high volumetric capacity, low self-discharge, high discharge voltage, and good cycling performance. Limitations include the high cost of the material, and low thermal stability.
The manganese-based materials adopt a cubic crystal lattice system, which allows for three-dimensional lithium-ion diffusion.
Manganese cathodes are attractive because manganese is cheaper and because it could theoretically be used to make a more efficient, longer-lasting battery if its limitations could be overcome. Limitations include the tendency for manganese to dissolve into the electrolyte during cycling leading to poor cycling stability for the cathode.
Cobalt-based cathodes are the most common, however other materials are being researched with the goal of lowering costs and improving cell life.
, is a candidate for large-scale production of lithium-ion batteries such as electric vehicle applications due to its low cost, excellent safety, and high cycle durability. For example, Sony Fortelion batteries have retained 74% of their capacity after 8000 cycles with 100% discharge. A carbon
conductive agent Conductive agents are used to ensure electrode, electrodes have good charge and discharge performance. Usually, a certain amount of conductive material is added during the production of the pole piece, and the micro current is collected between the ...
is required to overcome its low electrical conductivity.
It is worth mentioning so-called "lithium-rich" cathodes, that can be produced from thraditional NCM layered cathode materials upon cycling them to voltages/charges higher than those corresponding to Li:M=1. Under such conditions a new semi-reversible redox transition at a higher voltage with ca. 0.4-0.8 electrons/metal site charge appears. This transition involves non-binding electron orbitals centered mostly on O atoms. Despite significant initial interest, this phenomenon did not result in marketable products because of a fast structural degradation (O2 evolution and lattice rearrangements) of such "lithium-rich" phases.
Anode
Negative electrode materials are traditionally constructed from graphite and other carbon materials, although newer silicon-based materials are being increasingly used (see
Nanowire battery
A nanowire battery uses nanowires to increase the surface area of one or both of its electrodes. Some designs (silicon, germanium and transition metal oxides), variations of the lithium-ion battery have been announced, although none are commerciall ...
). In 2016, 89% of lithium-ion batteries contained graphite (43% artificial and 46% natural), 7% contained amorphous carbon (either soft carbon or
hard carbon), 2% contained lithium titanate (LTO) and 2% contained silicon or tin-based materials.
These materials are used because they are abundant, electrically conducting and can
intercalate
Intercalation may refer to:
*Intercalation (chemistry), insertion of a molecule (or ion) into layered solids such as graphite
* Intercalation (timekeeping), insertion of a leap day, week or month into some calendar years to make the calendar foll ...
lithium ions to store electrical charge with modest volume expansion (~10%).
Graphite is the dominant material because of its low intercalation voltage and excellent performance. Various alternative materials with higher capacities have been proposed, but they usually have higher voltages, which reduces low energy density. Low voltage is the key requirement for anodes; otherwise, the excess capacity is useless in terms of energy density.
As graphite is limited to a maximum capacity of 372 mAh/g
much research has been dedicated to the development of materials that exhibit higher theoretical capacities, and overcoming the technical challenges that presently encumber their implementation. The extensive 2007 Review Article by Kasavajjula et al.
summarizes early research on silicon-based anodes for lithium-ion secondary cells. In particular, Hong Li et al.
showed in 2000 that the electrochemical insertion of lithium ions in silicon nanoparticles and silicon nanowires leads to the formation of an amorphous Li-Si alloy. The same year, Bo Gao and his doctoral advisor, Professor Otto Zhou described the cycling of electrochemical cells with anodes comprising silicon nanowires, with a reversible capacity ranging from at least approximately 900 to 1500 mAh/g.
To improve stability of the lithium anode, several approaches of installing a protective layer have been suggested.
Silicon is beginning to be looked at as an anode material because it can accommodate significantly more lithium ions, storing up to 10 times the electric charge, however this alloying between lithium and silicon results in significant volume expansion (ca. 400%),
which causes catastrophic failure for the cell. Silicon has been used as an anode material but the insertion and extraction of
\scriptstyle Li+ can create cracks in the material. These cracks expose the Si surface to an electrolyte, causing decomposition and the formation of a solid electrolyte interphase (SEI) on the new Si surface (crumpled graphene encapsulated Si nanoparticles). This SEI will continue to grow thicker, deplete the available
\scriptstyle Li+, and degrade the capacity and cycling stability of the anode.
Electrolyte
Electrolyte alternatives have also played a significant role, for example the
lithium polymer battery
A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyt ...
. Polymer electrolytes are promising for minimizing the dendrite formation of lithium. Polymers are supposed to prevent short circuits and maintain conductivity.
The ions in the electrolyte diffuse because there are small changes in the electrolyte concentration. Linear diffusion is only considered here. The change in concentration ''c'', as a function of time ''t'' and distance ''x'', is
:
In this equation, ''D'' is the
diffusion coefficient
Diffusivity, mass diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion). Diffusivity is enco ...
for the lithium ion. It has a value of in the electrolyte. The value for ''ε'', the porosity of the electrolyte, is 0.724.
Formats
Cells
Li-ion cells (as distinct from entire batteries) are available in various shapes, which can generally be divided into four groups:
* Small cylindrical (solid body without terminals, such as those used in most e-bikes and most
electric vehicle battery
An electric vehicle battery (EVB, also known as a traction battery) is a rechargeable battery used to power the electric motors of a battery electric vehicle (BEV) or hybrid electric vehicle (HEV). Typically lithium-ion batteries, they are spec ...
and older laptop batteries); there a several
standard lithium-ion cylinder sizes.
* Large cylindrical (solid body with large threaded terminals)
* Flat or pouch (soft, flat body, such as those used in cell phones and newer laptops; these are
lithium-ion polymer batteries
A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrol ...
.
* Rigid plastic case with large threaded terminals (such as electric vehicle traction packs)
Cells with a cylindrical shape are made in a characteristic "
swiss roll
A Swiss roll, jelly roll (United States), roll cake, cream roll, roulade or Swiss log is a type of rolled sponge cake filled with whipped cream, jam, or icing. The origins of the term are unclear; in spite of the name "Swiss roll", the cake i ...
" manner (known as a "jelly roll" in the US), which means it is a single long "sandwich" of the positive electrode, separator, negative electrode, and separator rolled into a single spool. The shape of the jelly roll in cylindrical cells can be approximated by an
Archimedean spiral
The Archimedean spiral (also known as the arithmetic spiral) is a spiral named after the 3rd-century BC Greek mathematician Archimedes. It is the locus corresponding to the locations over time of a point moving away from a fixed point with a con ...
. One advantage of cylindrical cells compared to cells with stacked electrodes is the faster production speed. One disadvantage of cylindrical cells can be a large radial temperature gradient inside the cells developing at high discharge currents.
The absence of a case gives pouch cells the highest gravimetric energy density; however, for many practical applications they still require an external means of containment to prevent expansion when their
state of charge
State of charge (SoC) is the level of charge of an electric battery relative to its capacity. The units of SoC are percentage points (0% = empty; 100% = full). An alternative form of the same measure is the depth of discharge (DoD), the inverse ...
(SOC) level is high, and for general structural stability of the battery pack of which they are part. Both rigid plastic and pouch-style cells are sometimes referred to as
prismatic
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical ...
cells due to their rectangular shapes. Battery technology analyst Mark Ellis of Munro & Associates sees three basic Li-ion battery types used in modern (~2020) electric vehicle batteries at scale: ''cylindrical cells'' (e.g., Tesla), ''prismatic pouch'' (e.g., from
LG), and ''prismatic can cells'' (e.g., from LG,
Samsung
The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
,
Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation, headquartered in Kadoma, Osaka, Kadoma, Osaka P ...
, and others). Each form factor has characteristic advantages and disadvantages for EV use.
[
]
Since 2011, several research groups have announced demonstrations of
lithium-ion flow batteries that suspend the cathode or anode material in an aqueous or organic solution.
In 2014,
Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation, headquartered in Kadoma, Osaka, Kadoma, Osaka P ...
created the smallest Li-ion cell. It is
pin
A pin is a device used for fastening objects or material together.
Pin or PIN may also refer to:
Computers and technology
* Personal identification number (PIN), to access a secured system
** PIN pad, a PIN entry device
* PIN, a former Dutch ...
shaped. It has a diameter of 3.5mm and a weight of 0.6g. A
coin cell
A button cell, watch battery, or coin battery is a small single-cell battery shaped as a squat cylinder typically in diameter and high — resembling a button. Stainless steel usually forms the bottom body and positive terminal of the cell; in ...
form factor resembling that of ordinary lithium batteries is available since as early as 2006 for LiCoO
2 cells, usually designated with a "LiR" prefix.
Batteries
![Nissan Leaf 012](https://upload.wikimedia.org/wikipedia/commons/4/40/Nissan_Leaf_012.JPG)
A ''battery'' (also called a ''battery pack'') consists of multiple connected lithium-ion cells. Battery packs for large consumer electronics like laptop computers also contain temperature sensors,
voltage regulator
A voltage regulator is a system designed to automatically maintain a constant voltage. A voltage regulator may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components ...
circuits,
voltage taps, and charge-state monitors. These components minimize safety risks like overheating and
short circuit
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit ...
ing.
To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective and more efficient than connecting a single large battery.
Uses
The vast majority of commercial Li-ion batteries are used in
consumer electronics
Consumer electronics or home electronics are electronic (analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usually r ...
and
electric vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s. Such devices include:
* ''Portable devices'': these include
mobile phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
s and
smartphones
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...
,
laptop
A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
s and
tablets,
digital camera
A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile device ...
s and
camcorder
A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-swa ...
s,
electronic cigarette
An electronic cigarette is an electronic device that simulates tobacco smoking. It consists of an atomizer, a power source such as a battery, and a container such as a cartridge or tank. Instead of smoke, the user inhales vapor. As such ...
s,
handheld game console
A handheld game console, or simply handheld console, is a small, portable self-contained video game console with a built-in screen, game controls and speakers. Handheld game consoles are smaller than home video game consoles and contain the cons ...
s and
torches (flashlights).
* ''
Power tools
A power tool is a tool that is actuated by an additional power source and mechanism other than the solely manual labor used with hand tools. The most common types of power tools use electric motors. Internal combustion engines and compressed air ...
'': Li-ion batteries are used in tools such as
cordless drills,
sander
A sander is a power tool used to smooth surfaces by abrasion with sandpaper. Sanders have a means to attach the sandpaper and a mechanism to move it rapidly contained within a housing with means to hand-hold it or fix it to a workbench. Woodwo ...
s,
saw
A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut through material, very often wood, though sometimes metal or stone. The cut is made by placing the toothed edge against the material and mo ...
s, and a variety of garden equipment including
whipper-snipper
A string trimmer, also known by the portmanteau strimmer and the trademarks Weedwacker, Weed eater and Whipper Snipper. is a garden tool for cutting grass, small weeds, and groundcover. It uses a whirling monofilament line instead of a blade ...
s and
hedge trimmer
A hedge trimmer, shrub trimmer, or bush trimmerAs with the term ''scissors'', the plural terms "hedge trimmers" + c. are often used for individual trimming tools. is a gardening tool or machine used for trimming (cutting, pruning) hedges or so ...
s.
* ''
Electric vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s'':
electric vehicle batteries
An electric vehicle battery (EVB, also known as a traction battery) is a rechargeable battery used to power the electric motors of a battery electric vehicle (BEV) or hybrid electric vehicle (HEV). Typically lithium-ion batteries, they are sp ...
are used in
electric car
An electric car, battery electric car, or all-electric car is an automobile that is propelled by one or more electric motors, using only energy stored in batteries. Compared to internal combustion engine (ICE) vehicles, electric cars are quie ...
s,
hybrid vehicle
A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids.
The basic princip ...
s,
electric motorcycles and scooters
Electric motorcycles and scooters are plug-in electric vehicles with two or three wheels. Power is supplied by a rechargeable battery which drives one or more electric motors. Electric scooters are distinguished from motorcycles by having a st ...
,
electric bicycle
An electric bicycle (e-bike, eBike, etc.) is a motorized bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fall into two broad categories: bikes that assis ...
s,
personal transporter
A personal transporter (also powered transporter, electric rideable, personal light electric vehicle, personal mobility device, etc.) is any of a class of compact, mostly recent (21st century), motorised micromobility vehicle for transporting an ...
s and advanced
electric wheelchair
A motorized wheelchair, powerchair, electric wheelchair or electric-powered wheelchair (EPW) is a wheelchair that is propelled by means of an electric motor (usually using differential steering) rather than human power, manual power. Motorized wh ...
s. Also
radio-controlled model
A radio-controlled model (or RC model) is a Physical model, model that is steering, steerable with the use of radio control. All types of model vehicles have had RC systems installed in them, including radio-controlled car, ground vehicles, radio ...
s,
model aircraft
A model aircraft is a small unmanned aircraft. Many are replicas of real aircraft. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed static, display, or shelf models.
Aircraft manufactur ...
,
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
, and the
Mars ''Curiosity'' rover.
More niche uses include backup power in telecommunications applications. Lithium-ion batteries are also frequently discussed as a potential option for
grid energy storage
Grid energy storage (also called large-scale energy storage) is a collection of methods used for energy storage on a large scale within an electrical power grid. Electrical energy is stored during times when electricity is plentiful and inexp ...
, although they are not yet cost-competitive at scale.
Performance
Because lithium-ion batteries can have a variety of positive and negative electrode materials, the energy density and voltage vary accordingly.
The
open-circuit voltage
Open-circuit voltage (abbreviated as OCV or VOC) is the difference of electrical potential between two terminals of an electronic device when disconnected from any circuit. There is no external load connected. No external electric current f ...
is higher than in
aqueous batteries (such as
lead–acid,
nickel–metal hydride and
nickel-cadmium).
Internal resistance
A practical electrical power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This impedance is termed the internal resistance of the source. ...
increases with both cycling and age, although this depends strongly on the voltage and temperature the batteries are stored at. Rising internal resistance causes the voltage at the terminals to drop under load, which reduces the maximum current draw. Eventually, increasing resistance will leave the battery in a state such that it can no longer support the normal discharge currents requested of it without unacceptable voltage drop or overheating.
Batteries with a lithium iron phosphate positive and graphite negative electrodes have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide positives with graphite negatives have a 3.7 V nominal voltage with a 4.2 V maximum while charging. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. In 2015 researchers demonstrated a small 600 mAh capacity battery charged to 68 percent capacity in two minutes and a 3,000 mAh battery charged to 48 percent capacity in five minutes. The latter battery has an energy density of 620 W·h/L. The device employed heteroatoms bonded to graphite molecules in the anode.
Performance of manufactured batteries has improved over time. For example, from 1991 to 2005 the energy capacity per price of lithium ion batteries improved more than ten-fold, from 0.3 W·h per dollar to over 3 W·h per dollar. In the period from 2011 to 2017, progress has averaged 7.5% annually.
Overall, between 1991 and 2018, prices for all types of lithium-ion cells (in dollars per kWh) fell approximately 97%.
Over the same time period, energy density more than tripled.
Efforts to increase energy density contributed significantly to cost reduction.
Differently sized cells with similar chemistry can also have different energy densities. The
21700 cell has 50% more energy than the
18650 cell, and the bigger size reduces heat transfer to its surroundings.
Lifespan
Life of a lithium-ion battery is typically defined as the number of full charge-discharge cycles to reach a failure threshold in terms of capacity loss or impedance rise. Manufacturers' datasheet typically uses the word "cycle life" to specify lifespan in terms of the number of cycles to reach 80% of the rated battery capacity. Simple storing lithium-ion batteries in the charged state also reduces their capacity (the amount of cyclable Li+) and increases the cell resistance (primarily due to the continuous growth of the
solid electrolyte interface
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
on the
anode
An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
. Calendar life is used to represent the whole life cycle of battery involving both the cycle and inactive storage operations. Battery cycle life is affected by many different stress factors including temperature, discharge current, charge current, and state of charge ranges (depth of discharge).
Batteries are not fully charged and discharged in real applications such as smartphones, laptops and electric cars and hence defining battery life via full discharge cycles can be misleading. To avoid this confusion, researchers sometimes use cumulative discharge
defined as the total amount of charge (Ah) delivered by the battery during its entire life or equivalent full cycles,
which represents the summation of the partial cycles as fractions of a full charge-discharge cycle. Battery degradation during storage is affected by temperature and battery state of charge (SOC) and a combination of full charge (100% SOC) and high temperature (usually > 50 °C) can result in sharp capacity drop and gas generation. Multiplying the battery cumulative discharge by the rated nominal Voltage gives the total energy delivered over the life of the battery. From this one can calculate the cost per kWh of the energy (including the cost of charging).
Over their lifespan batteries degrade gradually leading to reduced capacity (and, in some cases, lower operating cell voltage) due to a variety of chemical and mechanical changes to the electrodes.
[.]
Several degradation processes occur in lithium-ion batteries, some during cycling, some during storage, and some all the time:
[.] Degradation is strongly temperature-dependent: degradation at room temperature is minimal but increases for batteries stored or used in hot or cold environments.
High charge levels also hasten
capacity loss. Some of the most prominent mechanisms include:
[.]
(1) Reduction of the organic carbonate electrolyte at the anode, which results in the growth of
Solid Electrolyte Interface
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
(SEI), where Li+ ions get irreversibly trapped, i.e. loss of lithium inventory. This shows as increased ohmic impedance and reduced Ah charge. At constant temperature the SEI film thickness (and therefore, the SEI resistance and the lost in cyclable Li+) increases as a square root of the time spent in the charged state. The number of cycles is not a useful metrics in characterizing this main degradation pathway. Under high temperatures or in the presence of a mechanical damage the electrolyte reduction can proceed explosively.
(2) Lithium metal plating also results in the loss of lithium inventory (cyclable Ah charge), as well as internal short-circuiting and ignition of a battery. Once Li plating commences during cycling, it results in larger slopes of capacity loss per cycle and resistance increase per cycle.
(3) Loss of the (negative or positive) electroactive materials due to dissolution (e.g. of Mn(3+) species), cracking, exfoliation, detachment or even simple regular volume change during cycling. It shows up as both charge and power fade (increased resistance). Both positive and negative electrode materials are subject to fracturing due to the volumetric strain of repeated (de)lithiation cycles.
(4) Structural degradation of cathode materials, such as Li+/Ni2+ cation mixing in nickel-rich materials. This manifests as “electrode saturation", loss of cyclable Ah charge and as a "voltage fade".
(5) Other material degradations. Negative copper current collector is particularly prone to corrosion/dissolution at low cell voltages. PVDF binder also degrades, causing the detachment of the electroactive materials, and the loss of cyclable Ah charge.
![2022-Vermeer-F2](https://upload.wikimedia.org/wikipedia/commons/d/d9/2022-Vermeer-F2.jpg)
These are shown in the figure on the right. A change from one main degradation mechanism to another appears as a knee (slope change) in the capacity vs. cycle number plot.
[
A more detailed description of some of these mechanisms is provided below:
(1) The negative (anode) SEI layer, a passivation coating formed by electrolyte (such as ethylenecarbonate) reduction products, is essential for providing Li+ ion conduction, while preventing electron transfer (and, thus, further solvent reduction). Under typical operating conditions, the negative SEI layer reaches a fixed thickness after the first few charges (formation cycles), allowing the device to operate for years. However, at elevated temperatures or due to mechanical detachment of the negative SEI, this ]exothermic
In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e ...
electrolyte reduction can proceed violently and lead to an explosion via several reactions. Lithium-ion batteries are prone to capacity fading over hundreds to thousands of cycles. Formation of the SEI consumes lithium ions, reducing the overall charge and discharge efficiency of the electrode material. as a decomposition product, various SEI-forming additives can be added to the electrolyte to promote the formation of a more stable SEI that remains selective for lithium ions to pass through while blocking electrons. Cycling cells at high temperature or at fast rates can promote the degradation of Li-ion batteries due in part to the degradation of the SEI or lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
plating. Charging Li-ion batteries beyond 80% can drastically accelerate battery degradation.
Depending on the electrolyte and additives, common components of the SEI layer that forms on the anode include a mixture of lithium oxide, lithium fluoride
Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid, that transitions to white with decreasing crystal size. Although odorless, lithium fluoride has a bitter-saline taste. Its structure is analogous to ...
and semicarbonates (e.g., lithium alkyl carbonates). At elevated temperatures, alkyl carbonates in the electrolyte decompose into insoluble species such as that increases the film thickness. This increases cell impedance and reduces cycling capacity. Gases formed by electrolyte decomposition can increase the cell's internal pressure and are a potential safety issue in demanding environments such as mobile devices. Below 25 °C, plating of metallic Lithium on the anodes and subsequent reaction with the electrolyte is leading to loss of cyclable Lithium. Extended storage can trigger an incremental increase in film thickness and capacity loss. Charging at greater than 4.2 V can initiate Li+ plating on the anode, producing irreversible capacity loss.
Electrolyte degradation mechanisms include hydrolysis and thermal decomposition. At concentrations as low as 10 ppm, water begins catalyzing a host of degradation products that can affect the electrolyte, anode and cathode. participates in an equilibrium reaction with LiF and . Under typical conditions, the equilibrium lies far to the left. However the presence of water generates substantial LiF, an insoluble, electrically insulating product. LiF binds to the anode surface, increasing film thickness. hydrolysis yields , a strong Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
that reacts with electron-rich species, such as water. reacts with water to form hydrofluoric acid
Hydrofluoric acid is a Solution (chemistry), solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly Corrosive substance, corrosive. It is used to make most fluorine-containing compounds; examples include th ...
(HF) and phosphorus oxyfluoride
Phosphoryl fluoride (commonly called phosphorus oxyfluoride) is a compound with the chemical formula . It is a colorless gas that hydrolyzes rapidly.
Synthesis and reactions
Phosphorus oxyfluoride is prepared by partial hydrolysis of phosphorus p ...
. Phosphorus oxyfluoride in turn reacts to form additional HF and difluorohydroxy phosphoric acid
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...
. HF converts the rigid SEI film into a fragile one. On the cathode, the carbonate solvent can then diffuse onto the cathode oxide over time, releasing heat and potentially causing thermal runaway. Decomposition of electrolyte salts and interactions between the salts and solvent start at as low as 70 °C. Significant decomposition occurs at higher temperatures. At 85 °C transesterification
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can ...
products, such as dimethyl-2,5-dioxahexane carboxylate (DMDOHC) are formed from EC reacting with DMC.
Batteries generate heat when being charged or discharged, especially at high currents. Large battery packs, such as those used in electric vehicles, are generally equipped with thermal management systems that maintain a temperature between and . Pouch and cylindrical cell temperatures depend linearly on the discharge current. Poor internal ventilation may increase temperatures. For large batteries consisting of multiple cells, non-uniform temperatures can lead to non-uniform and accelerated degradation. In contrast, the calendar life of cells is not affected by high charge states.
Positive SEI layer in lithium-ion batteries is much less understood than the negative SEI. It is believed to have a low-ionic conductivity and shows up as an increased interfacial resistance of the cathode during cycling and calendar aging.[/>]
(2) The randomness of the metallic lithium embedded in the anode during intercalation results in dendrites
Dendrites (from Greek δένδρον ''déndron'', "tree"), also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the n ...
formation. Over time the dendrites can accumulate and pierce the separator, causing a short circuit
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit ...
leading to heat, fire or explosion. This process is referred to as thermal runaway
Thermal runaway describes a process that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way t ...
. Lithium plating is the most serious concern, when Li-ion batteries are charged at cold temperatures.
(3) Certain manganese containing cathodes can degrade by the Hunter degradation mechanism resulting in manganese dissolution and reduction on the anode. By the Hunter mechanism for , hydrofluoric acid catalyzes the loss of manganese through disproportionation of a surface trivalent manganese to form a tetravalent manganese and a soluble divalent manganese:
: 2Mn3+ → Mn2++ Mn4+
Material loss of the spinel results in capacity fade. Temperatures as low as 50 °C initiate Mn2+ deposition on the anode as metallic manganese with the same effects as lithium and copper plating. Cycling over the theoretical max and min voltage plateaus destroys the crystal lattice
In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by
: \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...
via Jahn-Teller distortion, which occurs when Mn4+ is reduced to Mn3+ during discharge. Storage of a battery charged to greater than 3.6 V initiates electrolyte oxidation by the cathode and induces SEI layer formation on the cathode. As with the anode, excessive SEI formation forms an insulator resulting in capacity fade and uneven current distribution. Storage at less than 2 V results in the slow degradation of and cathodes, the release of oxygen and irreversible capacity loss.
(4) Cation mixing is the main reason for the capacity decline of the Ni-rich cathode materials. As the Ni content in the NCM layered material increases the capacity will increase, which is the result of two-electron of Ni2+/Ni4+ redox reaction (please note, that Mn remains electrochemically inactive in the 4+ state) but, increasing the Ni content results in a significant degree of mixing of Ni2+ and Li+ cations due to the closeness of their ionic radius (Li+ =0.076 nm and Ni2+ =0.069 nm). During charge/discharge cycling, the Li+ in the cathode cannot be easily be extracted and the existence of Ni2+ in the Li layer blocks the diffusion of Li+, resulting in both capacity loss and increased ohmic resistance.
(5) Discharging below 2 V can also result in the dissolution of the copper anode current collector and, thus, in catastrophic internal short-circuiting on recharge.
The IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...
standard 1188–1996 recommends replacing Lithium-ion batteries in an electric vehicle, when their charge capacity drops to 80% of the nominal value. In what follows, we shall use the 20% capacity loss as a comparison point between different studies. We shall note, nevertheless, that the linear model of degradation (the constant % of charge loss per cycle or per calendar time) is not always applicable, and that a “knee point”, observed as a change of the slope, and related to the change of the main degradation mechanism, is often observed.
Most studies of lithium-ion battery aging have been done at elevated (50-60 °C) temperatures in order to complete the experiments sooner. Under these storage conditions, fully charged nickel-cobalt-aluminum and lithium-iron phosphate cells loose ca. 20% of their cyclable charge in 1-2 year. It is believed, that the aforementioned anode aging is the most important degradation pathways in these cases. On the other hand, manganese-based cathodes show a (ca. 20-50%) faster degradation under these conditions, probably due to the additional mechanism of Mn ion dissolution.[ At 25 °C the degradation of lithium-ion batteries seems to follow the same pathway(s) as the degradation at 50 °C, but with half the speed.][ In other words, based on the limited extrapolated experimental data, lithium-ion batteries are expected to lose irreversibly ca. 20% of their cyclable charge in 3–5 years or 1000-2000 cycles at 25 °C.][ Lithium-ion batteries with titanate anodes do not suffer from SEI growth, and last longer (>5000 cycles) than graphite anodes. However, in complete cells other degradation mechanisms (i.e. the dissolution of Mn3+ and the Ni3+/Li+ place exchange, decomposition of PVDF binder and particle detachment) show up after 1000–2000 days, and the use titanate anode does not improve full cell durability in practice.
]
Safety
Fire hazard
Lithium-ion batteries can be a safety hazard since they contain a flammable electrolyte and may become pressurized if they become damaged. A battery cell charged too quickly could cause a short circuit
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit ...
, leading to explosions and fires. A Li-ion battery fire can be started due to (1) thermal abuse, e.g. poor cooling or external fire, (2) electrical abuse, e.g. overcharge or external short circuit, (3) mechanical abuse, e.g. penetration or crash, or (4) internal short circuit, e.g. due to manufacturing flaws or aging. Because of these risks, testing standards are more stringent than those for acid-electrolyte batteries, requiring both a broader range of test conditions and additional battery-specific tests, and there are shipping limitations imposed by safety regulators. There have been battery-related recalls by some companies, including the 2016 Samsung
The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
Galaxy Note 7 recall for battery fires.
Lithium-ion batteries have a flammable liquid electrolyte. A faulty battery can cause a serious fire
Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products.
At a certain point in the combustion reaction, called the ignition ...
. Faulty chargers can affect the safety of the battery because they can destroy the battery's protection circuit. While charging at temperatures below 0 °C, the negative electrode of the cells gets plated with pure lithium, which can compromise the safety of the whole pack.
Short-circuiting a battery will cause the cell to overheat and possibly to catch fire. Smoke from thermal runaway in a Li-ion battery is both flammable and toxic. The fire energy content (electrical + chemical) of cobalt-oxide cells is about 100 to 150 kJ/(A·h
An ampere hour or amp hour (symbol: A⋅h or A h; often simplified as Ah) is a Unit of measurement, unit of electric charge, having Dimensional analysis, dimensions of electric current multiplied by time, equal to the charge transferred by a ...
), most of it chemical.
Around 2010, large lithium-ion batteries were introduced in place of other chemistries to power systems on some aircraft; , there had been at least four serious lithium-ion battery fires, or smoke, on the Boeing 787 passenger aircraft, introduced in 2011, which did not cause crashes but had the potential to do so. UPS Airlines Flight 6
UPS Airlines Flight 6 was a cargo flight operated by UPS Airlines. On September 3, 2010, the Boeing 747-400F flying the route between Dubai, United Arab Emirates, and Cologne, Germany, developed an in-flight fire, which caused the aircraft to c ...
crashed in Dubai
Dubai (, ; ar, دبي, translit=Dubayy, , ) is the most populous city in the United Arab Emirates (UAE) and the capital of the Emirate of Dubai, the most populated of the 7 emirates of the United Arab Emirates.The Government and Politics of ...
after its payload of batteries spontaneously ignited.
To reduce fire hazards, research projects are intended to develop non-flammable electrolytes.
Damaging and overloading
If a lithium-ion battery is damaged, crushed, or is subjected to a higher electrical load without having overcharge protection, then problems may arise. External short circuit can trigger a battery explosion.
If overheated or overcharged, Li-ion batteries may suffer thermal runaway
Thermal runaway describes a process that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way t ...
and cell rupture. In extreme cases this can lead to leakage, explosion or fire. To reduce these risks, many lithium-ion cells (and battery packs) contain fail-safe circuitry that disconnects the battery when its voltage is outside the safe range of 3–4.2 V per cell, or when overcharged or discharged. Lithium battery packs, whether constructed by a vendor or the end-user, without effective battery management circuits are susceptible to these issues. Poorly designed or implemented battery management circuits also may cause problems; it is difficult to be certain that any particular battery management circuitry is properly implemented.
Voltage limits
Lithium-ion cells are susceptible to stress by voltage ranges outside of safe ones between 2.5 and 3.65/4.1/4.2 or 4.35V (depending on the components of the cell). Exceeding this voltage range results in premature aging and in safety risks due to the reactive components in the cells. When stored for long periods the small current draw of the protection circuitry may drain the battery below its shutoff voltage; normal chargers may then be useless since the battery management system (BMS) may retain a record of this battery (or charger) "failure". Many types of lithium-ion cells cannot be charged safely below 0 °C, as this can result in plating of lithium on the anode of the cell, which may cause complications such as internal short-circuit paths.
Other safety features are required in each cell:
* Shut-down separator (for overheating)
* Tear-away tab (for internal pressure relief)
* Vent (pressure relief in case of severe outgassing)
* Thermal interrupt (overcurrent/overcharging/environmental exposure)
These features are required because the negative electrode produces heat during use, while the positive electrode may produce oxygen. However, these additional devices occupy space inside the cells, add points of failure, and may irreversibly disable the cell when activated. Further, these features increase costs compared to nickel metal hydride batteries
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to r ...
, which require only a hydrogen/oxygen recombination device and a back-up pressure valve. Contaminants inside the cells can defeat these safety devices. Also, these features can not be applied to all kinds of cells, e.g., prismatic high current cells cannot be equipped with a vent or thermal interrupt. High current cells must not produce excessive heat or oxygen, lest there be a failure, possibly violent. Instead, they must be equipped with internal thermal fuses which act before the anode and cathode reach their thermal limits.
Replacing the lithium cobalt oxide
Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
positive electrode material in lithium-ion batteries with a lithium metal phosphate such as lithium iron phosphate (LFP) improves cycle counts, shelf life and safety, but lowers capacity. As of 2006, these safer lithium-ion batteries were mainly used in electric car
An electric car, battery electric car, or all-electric car is an automobile that is propelled by one or more electric motors, using only energy stored in batteries. Compared to internal combustion engine (ICE) vehicles, electric cars are quie ...
s and other large-capacity battery applications, where safety is critical.
Recalls
* In October 2004, Kyocera Wireless
Kyocera Communications, Inc. (pronounced "key-yo-sarah") is an American manufacturer of mobile phones for wireless service providers in the United States and Canada. Kyocera Communications, Inc. is a wholly owned subsidiary of Kyocera Corporation, ...
recalled approximately 1 million mobile phone batteries to identify counterfeit
To counterfeit means to imitate something authentic, with the intent to steal, destroy, or replace the original, for use in illegal transactions, or otherwise to deceive individuals into believing that the fake is of equal or greater value tha ...
s.
* In December 2005, Dell
Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies.
Dell sells personal computers (PCs), servers, data ...
recalled approximately 22,000 laptop computer
A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
batteries, and 4.1 million in August 2006.
* In 2006, approximately 10 million Sony batteries used in Dell, Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...
, Apple
An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
, Lenovo, Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation, headquartered in Kadoma, Osaka, Kadoma, Osaka P ...
, Toshiba
, commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure system ...
, Hitachi
() is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
, Fujitsu
is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...
and Sharp
Sharp or SHARP may refer to:
Acronyms
* SHARP (helmet ratings) (Safety Helmet Assessment and Rating Programme), a British motorcycle helmet safety rating scheme
* Self Help Addiction Recovery Program, a charitable organisation founded in 19 ...
laptops were recalled. The batteries were found to be susceptible to internal contamination by metal particles during manufacture. Under some circumstances, these particles could pierce the separator, causing a dangerous short circuit.
* In March 2007, computer manufacturer Lenovo
Lenovo Group Limited, often shortened to Lenovo ( , ), is a Chinese Multinational corporation, multinational technology company specializing in designing, manufacturing, and marketing consumer electronics, Personal computer, personal computers, ...
recalled approximately 205,000 batteries at risk of explosion.
* In August 2007, mobile phone manufacturer Nokia
Nokia Corporation (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporatio ...
recalled over 46 million batteries at risk of overheating and exploding. One such incident occurred in the Philippines involving a Nokia N91
The Nokia N91 is a smartphone produced by Nokia as part of their Nseries line of portable devices. It was announced on April 27, 2005 along with N70 and N90 as the first three Nseries devices. The N91 ran on Symbian-based S60 3rd Edition (the ...
, which used the BL-5C battery.
* In September 2016, Samsung
The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
recalled approximately 2.5 million Galaxy Note 7 phones after 35 confirmed fires. The recall was due to a manufacturing design fault in Samsung's batteries which caused internal positive and negative poles to touch.
Transport restrictions
IATA
The International Air Transport Association (IATA ) is a trade association of the world's airlines founded in 1945. IATA has been described as a cartel since, in addition to setting technical standards for airlines, IATA also organized tariff ...
estimates that over a billion lithium metal
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ele ...
and lithium-ion cells are flown each year.[ Some kinds of lithium batteries may be prohibited aboard aircraft because of the fire hazard. Some postal administrations restrict air shipping (including EMS) of lithium and lithium-ion batteries, either separately or installed in equipment.
]
Environmental impact
Extraction of lithium, nickel, and cobalt, manufacture of solvents, and mining byproducts present significant environmental and health hazards.
Lithium extraction can be fatal to aquatic life due to water pollution. It is known to cause surface water contamination, drinking water contamination, respiratory problems, ecosystem degradation and landscape damage. It also leads to unsustainable water consumption in arid regions (1.9 million liters per ton of lithium). Massive byproduct generation of lithium extraction also presents unsolved problems, such as large amounts of magnesium and lime waste.
Lithium mining takes place in North and South America, Asia, South Africa, Australia, and China.
Cobalt for Li-ion batteries is largely mined in the Congo (see also Mining industry of the Democratic Republic of the Congo
The mining industry of the Democratic Republic of the Congo produces copper, diamonds, tantalum, tin, gold, and more than 63% of global cobalt production. Minerals and petroleum are central to the DRC's economy, making up more than 95% of value of ...
)
Manufacturing a kg of Li-ion battery takes about 67 megajoule (MJ) of energy. The global warming potential
Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time f ...
of lithium-ion batteries manufacturing strongly depends on the energy source used in mining and manufacturing operations, and is difficult to estimate, but one 2019 study estimated 73 kg CO2e/kWh. Effective recycling can reduce the carbon footprint of the production significantly.
Solid waste and recycling
Since Li-ion batteries contain less toxic metals
Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, ...
than other types of batteries which may contain lead or cadmium, they are generally categorized as non-hazardous waste . Li-ion battery elements including iron, copper, nickel and cobalt are considered safe for incinerators
Incineration is a list of solid waste treatment technologies, waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-ene ...
and landfills
A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...
. These metals can be recycle
Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...
d, usually by burning away the other materials, but mining generally remains cheaper than recycling; recycling may cost $3/kg, and in 2019 less than 5% of lithium ion batteries were being recycled. Since 2018, the recycling yield was increased significantly, and recovering lithium, manganese, aluminum, the organic solvents of the electrolyte, and graphite is possible at industrial scales. The most expensive metal involved in the construction of the cell is cobalt. Lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
is less expensive than other metals used and is rarely recycled, but recycling could prevent a future shortage.
Accumulation of battery waste presents technical challenges and health hazards. Since the environmental impact of electric cars is heavily affected by the production of lithium-ion batteries, the development of efficient ways to repurpose waste is crucial. Recycling is a multi-step process, starting with the storage of batteries before disposal, followed by manual testing, disassembling, and finally the chemical separation of battery components. Re-use of the battery is preferred over complete recycling as there is less embodied energy
Embodied energy is the sum of all the energy required to produce any goods or services, considered as if that energy was incorporated or 'embodied' in the product itself. The concept can be useful in determining the effectiveness of energy-produ ...
in the process. As these batteries are a lot more reactive than classical vehicle waste like tire rubber, there are significant risks to stockpiling used batteries.
Pyrometallurgical recovery
The pyrometallurgical
Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable ...
method uses a high-temperature furnace to reduce the components of the metal oxides in the battery to an alloy of Co, Cu, Fe, and Ni. This is the most common and commercially established method of recycling and can be combined with other similar batteries to increase smelting efficiency and improve thermodynamics
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...
. The metal current collector
Electric current collectors are used by trolleybuses, trams, electric locomotives or EMUs to carry electrical power from overhead lines, electrical third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for ...
s aid the smelting process, allowing whole cells or modules to be melted at once. The product of this method is a collection of metallic alloy, slag
Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...
, and gas. At high temperatures, the polymers used to hold the battery cells together burn off and the metal alloy can be separated through a hydrometallurgical process into its separate components. The slag can be further refined or used in the cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...
industry. The process is relatively risk-free and the exothermic
In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e ...
reaction from polymer combustion reduces the required input energy. However, in the process, the plastics, electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
s, and lithium salts will be lost.
Hydrometallurgical metals reclamation
This method involves the use of aqueous solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be re ...
s to remove the desired metals from the cathode. The most common reagent is sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
. Factors that affect the leaching rate include the concentration of the acid, time, temperature, solid-to-liquid-ratio, and reducing agent
In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ).
Examples of substances that are commonly reducing agents include the Earth meta ...
. It is experimentally proven that H2O2 acts as a reducing agent to speed up the rate of leaching through the reaction:
2LiCoO2(s) + 3H2SO4 + H2O2 → 2CoSO4(aq) + Li2SO4 + 4H2O + O2
Once leached, the metals can be extracted through precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
reactions controlled by changing the pH level of the solution. Cobalt, the most expensive metal, can then be recovered in the form of sulfate, oxalate, hydroxide, or carbonate. 5More recently recycling methods experiment with the direct reproduction of the cathode from the leached metals. In these procedures, concentrations of the various leached metals are premeasured to match the target cathode and then the cathodes are directly synthesized.
The main issues with this method, however, is that a large volume of solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
is required and the high cost of neutralization. Although it's easy to shred up the battery, mixing the cathode and anode at the beginning complicates the process, so they will also need to be separated. Unfortunately, the current design of batteries makes the process extremely complex and it is difficult to separate the metals in a closed-loop battery system. Shredding and dissolving may occur at different locations.
Direct recycling
Direct recycling is the removal of the cathode or anode from the electrode, reconditioned, and then reused in a new battery. Mixed metal-oxides can be added to the new electrode with very little change to the crystal morphology. The process generally involves the addition of new lithium to replenish the loss of lithium in the cathode due to degradation from cycling. Cathode strips are obtained from the dismantled batteries, then soaked in NMP, and undergo sonication to remove excess deposits. It is treated hydrothermally with a solution containing LiOH/Li2SO4 before annealing.
This method is extremely cost-effective for noncobalt-based batteries as the raw materials do not make up the bulk of the cost. Direct recycling avoids the time-consuming and expensive purification steps, which is great for low-cost cathodes such as LiMn2O4 and LiFePO4. For these cheaper cathodes, most of the cost, embedded energy, and carbon footprint
A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
is associated with the manufacturing rather than the raw material. It is experimentally shown that direct recycling can reproduce similar properties to pristine graphite.
The drawback of the method lies in the condition of the retired battery. In the case where the battery is relatively healthy, direct recycling can cheaply restore its properties. However, for batteries where the state of charge is low, direct recycling may not be worth the investment. The process must also be tailored to the specific cathode composition, and therefore the process must be configured to one type of battery at a time. Lastly, in a time with rapidly developing battery technology, the design of a battery today may no longer be desirable a decade from now, rendering direct recycling ineffective.
Human rights impact
Extraction of raw materials for lithium ion batteries may present dangers to local people, especially land-based indigenous populations.
Cobalt sourced from the Democratic Republic of the Congo is often mined by workers using hand tools with few safety precautions, resulting in frequent injuries and deaths. Pollution from these mines has exposed people to toxic chemicals that health officials believe to cause birth defects and breathing difficulties. Human rights activists have alleged, and investigative journalism
Investigative journalism is a form of journalism in which reporters deeply investigate a single topic of interest, such as serious crimes, political corruption, or corporate wrongdoing. An investigative journalist may spend months or years rese ...
reported confirmation, that child labor
Child labour refers to the exploitation of children through any form of work that deprives children of their childhood, interferes with their ability to attend regular school, and is mentally, physically, socially and morally harmful. Such e ...
is used in these mines.
A study of relationships between lithium extraction companies and indigenous peoples in Argentina indicated that the state may not have protected indigenous peoples' right to free prior and informed consent, and that extraction companies generally controlled community access to information and set the terms for discussion of the projects and benefit sharing.
Development of the Thacker Pass lithium mine
The Thacker Pass Lithium Mine is a proposed lithium clay mining development project in Humboldt County, Nevada which is the largest known lithium deposit in the US, and one of the largest in the world. There has been significant exploration of ...
in Nevada, USA has met with protests and lawsuits from several indigenous tribes who have said they were not provided free prior and informed consent and that the project threatens cultural and sacred sites. Links between resource extraction and missing and murdered indigenous women
Missing and Murdered Indigenous Women (MMIW) is an epidemic of violence against Indigenous women in Canada, the United States, and Latin America; notably those in the FNIM (First Nations, Inuit, Métis) and Native American communities. Acros ...
have also prompted local communities to express concerns that the project will create risks to indigenous women. Protestors have been occupying the site of the proposed mine since January, 2021.
Research
Researchers are actively working to improve the power density, safety, cycle durability (battery life), recharge time, cost, flexibility, and other characteristics, as well as research methods and uses, of these batteries.
See also
* Borate oxalate The borate oxalates are chemical compounds containing borate and oxalate anions. Where the oxalate group is bound to the borate via oxygen, a more condensed anion is formed that balances less cations. These can be termed boro-oxalates, bis(oxalato)b ...
* Comparison of commercial battery types This is a list of commercially-available battery types summarizing some of their characteristics for ready comparison.
Common characteristics
Cost in USD, adjusted for inflation.
Typical. See for alternative electrode materials.
Rechargeable ...
* European Battery Alliance
The European Battery Alliance (EBA) is Europe's plan to create its own competitive and sustainable battery cell manufacturing value chain. Its purpose is to ensure that Europe benefits from the technological evolution in the Electric Vehicle Mark ...
* Nanowire battery
A nanowire battery uses nanowires to increase the surface area of one or both of its electrodes. Some designs (silicon, germanium and transition metal oxides), variations of the lithium-ion battery have been announced, although none are commerciall ...
* Solid-state battery
A solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries.
While solid electrolytes were first discovered ...
* Thin-film lithium-ion battery
The thin film lithium-ion battery is a form of solid-state battery. Its development is motivated by the prospect of combining the advantages of solid-state batteries with the advantages of thin-film manufacturing processes.
Thin-film construction ...
* Blade battery
Blade battery is a type of lithium iron phosphate (LFP) battery for electric vehicles designed and manufactured by FinDreams Battery, a subsidiary of Chinese manufacturing company BYD.
The Blade Battery is most commonly a 96 cm long and ...
* Flow battery
A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a ...
* VRLA battery
A valve regulated lead–acid (VRLA) battery, commonly known as a sealed lead–acid (SLA) battery, is a type of lead–acid battery characterized by a limited amount of electrolyte ("starved" electrolyte) absorbed in a plate separator or formed ...
References
Sources
*
*
External links
* .
List of World's Largest Lithium-ion Battery Factories (2020)
* ttps://www.nytimes.com/2021/09/08/technology/batteries-new-technology.html New More Efficient Lithium-ion Batteries''The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
''. September 2021.
NREL Innovation Improves Safety of Electric Vehicle Batteries
NREL
The National Renewable Energy Laboratory (NREL) in the US specializes in the research and development of renewable energy, energy efficiency, energy systems integration, and sustainable transportation. NREL is a federally funded research and d ...
, October 2015.
Degradation Mechanisms and Lifetime Prediction for Lithium-Ion Batteries
NREL
The National Renewable Energy Laboratory (NREL) in the US specializes in the research and development of renewable energy, energy efficiency, energy systems integration, and sustainable transportation. NREL is a federally funded research and d ...
, July 2015.
Impact of Temperature Extremes on Large Format Li-ion Batteries for Vehicle Applications
NREL
The National Renewable Energy Laboratory (NREL) in the US specializes in the research and development of renewable energy, energy efficiency, energy systems integration, and sustainable transportation. NREL is a federally funded research and d ...
, March 2013.
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