Solid-state electrolyte
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A solid-state electrolyte (SSE) is a solid ionic conductor and electron-insulating
material Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geologi ...
and it is the characteristic component of the
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 ...
. It is useful for applications in electrical energy storage (EES) in substitution of the liquid electrolytes found in particular in
lithium-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
. The main advantages are the absolute safety, no issues of leakages of toxic
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, low flammability, non-volatility, mechanical and thermal stability, easy processability, low self-discharge, higher achievable power density and cyclability. This makes possible, for example, the use of 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 ...
metal anode in a practical device, without the intrinsic limitations of a liquid
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 ...
thanks to the property of lithium dendrite suppression in the presence of a solid-state electrolyte membrane. The utilization of a high capacity anode and low
reduction potential Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...
, like
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 ...
with a specific capacity of 3860 mAh g−1 and a
reduction potential Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...
of -3.04 V vs
SHE She most commonly refers to: *She (pronoun), the third person singular, feminine, nominative case pronoun in modern English. She or S.H.E. may also refer to: Literature and films *'' She: A History of Adventure'', an 1887 novel by H. Rider Hagga ...
, in substitution of the traditional low capacity graphite, which exhibits a theoretical capacity of 372 mAh g−1 in its fully lithiated state of LiC6, is the first step in the realization of a lighter, thinner and cheaper rechargeable battery. Moreover, this allows the reach of gravimetric and volumetric energy densities, high enough to achieve 500 miles per single charge in an electric vehicle. Despite the promising advantages, there are still many limitations that are hindering the transition of SSEs from academia research to large-scale production, depending mainly on the poor ionic conductivity compared to that of liquid counterparts. However, many car
OEMs An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...
(Toyota, BMW, Honda, Hyundai) expect to integrate these systems into viable devices and to commercialize
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 ...
-based electric vehicles by 2025.


History

The first inorganic solid-state electrolytes were discovered by M. Faraday in the nineteenth century, these being silver sulfide (Ag2S) and lead(II) fluoride (PbF2). The first polymeric material able to conduct ions at the solid-state was PEO, discovered in the 1970s by V. Wright. The importance of the discovery was recognized in the early of 1980s. However, unresolved fundamental issues remain in order to fully understand the behavior of all-solid batteries, especially in the area of electrochemical interfaces. In recent years the needs of safety and performance improvements with respect to the state-of-the-art Li-ion chemistry are making
solid-state batteries 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 ...
very appealing and are now considered an encouraging technology to satisfy the need for long range
battery electric vehicles A battery electric vehicle (BEV), pure electric vehicle, only-electric vehicle, fully electric vehicle or all-electric vehicle is a type of electric vehicle (EV) that exclusively uses chemical energy stored in rechargeable battery packs, wi ...
of the near future. In March 2020, the Samsung Advanced Institute of Technology (SAIT) published research on an all-solid-state battery (ASSB) using an argyrodite-based solid-state electrolyte with a demonstrated energy density of 900 Wh L−1 and a stable cyclability of more than 1000 cycles, reaching for the first time a value close to the 1000 Wh L−1.


Properties

For Solid State Batteries (SSBs) / Solid Electrolytes (SEs) to become a major market challenger it must meet some key performance measurements. The major criteria that an SSB/SE should have are: * Ionic conductivity: Historically, SSBs have suffered from low ionic conductivities due to poor interfacial kinetics and mobility of ions in general. Hence an SE with a high ionic conductivity is of primary importance. High ionic conductivity (at least higher than 10−4 S cm−1) can be measured through electrochemical impedance spectroscopy (EIS) analysis. * Volumetric Energy Density: Along with high ionic conductivity the candidate must have the ability to be stacked within a single package, so it supplies high energy density to the Electric Vehicles. A high volumetric energy density is required so that the driving range of EVs can be increased between charges. * Power density: Sufficient power density (W/L) is needed to make energy available when needed which is also a measure of how quickly charging and discharging can take place. *Cycle life: Long cycle and shelf life are needed as conventional Li-ion batteries degrade after a few years. *Ionic transference number: High ionic transference number (the closest possible to 1) can be measured through a combination of chronoamperometry (CA) and
EIS Eis or EIS may refer to: Education * Eastern Independent Schools of Melbourne, in Australia * Educational Institute of Scotland, a trade union * Ekamai International School, in Bangkok, Thailand * English for Integrated Studies, a program in T ...
analysis. *Thermal, mechanical and electrochemical Stability: During device or car operation the SSBs may undergo large volume variations and face mechanical stress. Also, electrochemical stability at high operating electrode potentials which are of advantage when it comes to high energy density. Hence, it is important that their mechanical, thermal, and electrochemical stability are considered. High
mechanical strength The field of strength of materials, also called mechanics of materials, typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the re ...
(at least tens of MPa) can be measured through a traditional
tensile test Tensile testing, also known as tension testing, is a fundamental materials science and engineering test in which a sample is subjected to a controlled tension until failure. Properties that are directly measured via a tensile test are ultimat ...
. Wide electrochemical stability windows (ESW) (at least 4-5 V) can be measured through linear sweep voltammetry (LSV) or cyclic voltammetry (CV). * Compatibility: The SE must be compatible with the electrode materials used in batteries as there is already a high chance of increased resistance in SSBs due to limited contact area between electrolyte and electrode materials. It should also be stable in contact with Lithium metal. It should be lighter so that it can be used in portable electronic devices. High compatibility with the electrode material can be measured through
EIS Eis or EIS may refer to: Education * Eastern Independent Schools of Melbourne, in Australia * Educational Institute of Scotland, a trade union * Ekamai International School, in Bangkok, Thailand * English for Integrated Studies, a program in T ...
analysis repeated over more consecutive days. *Economic fabrication technologies: If SEs contain expensive materials like Ge it will make the production cost go up significantly. The production of an exemplar SSB will require the convergence of uncomplicated fabrication technologies like particle dispersion, mechanical mixing, film formation etc. It is hard for one material to fulfill all the above criteria, hence a number of other approaches can be utilized for example a hybrid electrolyte system which combines the advantages of inorganic and polymer electrolytes.


Categories

SSEs have the same role of a traditional liquid electrolyte and they are classified into all-solid-state electrolyte and quasi-solid-state electrolyte (QSSE). All-solid-state electrolytes are furthermore divided into inorganic solid electrolyte (ISE), solid polymer electrolyte (SPE) and composite polymer electrolyte (CPE). On the other hand, a QSSE, also called gel polymer electrolyte (GPE), is a freestanding membrane that contains a certain amount of liquid component immobilized inside the solid matrix. In general the nomenclatures SPE and GPE are used interchangeably but they have a substantially different ionic conduction mechanism: SPEs conducts ions through the interaction with the substitutional groups of the polymer chains, while GPEs conducts ions mainly in the solvent or plasticizer.


All-solid-state electrolyte

All-solid-state electrolytes are divided into inorganic solid electrolyte (ISE), solid polymer electrolyte (SPE) and composite polymer electrolyte (CPE). They are solid at room temperature and the ionic movement occurs at the solid-state. Their main advantage is the complete removal of any liquid component aimed to a greatly enhanced safety of the overall device. The main limitation is the ionic conductivity that tends to be much lower compared to a liquid counterpart. * Inorganic solid electrolyte (ISE) Inorganic solid electrolyte (ISE) are a particular type of all-solid-state electrolyte that is constituted by an inorganic material in the
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
line or
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 state, that conducts ions by diffusion through the lattice. The main advantages of this class of solid-state electrolyte are the high ionic conductivity (of the order of a few mS cm−2 at room-temperature), high modulus (of the order of GPa) and high transfer number compared to other classes of SSEs. They are generally brittle and with this comes a low compatibility and stability towards the electrode, with a rapidly increasing interfacial resistance and a complicated scale-up from academic to industry. They can be
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,
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
s or
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...
s-based and the crystalline structures include LISICON (lithium superionic conductor) (e.g. LGPS, LiSiPS, LiPS), argyrodite-like (e.g. Li6PS5X, X = Cl, Br, I),
garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...
s ( LLZO),
NASICON NASICON is an acronym for sodium (Na) Super Ionic CONductor, which usually refers to a family of solids with the chemical formula Na1+xZr2SixP3−xO12, 0 < x < 3. In a broader sense, it is also used for similar compounds where Na, Zr and/or Si ...
(sodium superionic conductor) (e.g. LTP, LATP, LAGP), lithium
nitride In chemistry, a nitride is an inorganic compound of nitrogen. The "nitride" anion, N3- ion, is very elusive but compounds of nitride are numerous, although rarely naturally occuring. Some nitrides have a find applications, such as wear-resistant ...
s (e.g. Li3N), lithium
hydride In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of ...
s (LiBH4),
perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure as (XIIA2+VIB4+X2−3), known as ...
s (e.g. lithium lanthanum titanate, " LLTO"), lithium
halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...
s (LYC, LYB)., RbAg4I5. Some ISEs can be glass ceramics assuming an amorphous state instead of a regular crystalline structure. Popular examples are lithium
phosphorus oxynitride Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Eart ...
(LIPON) and the lithium
thiophosphate Thiophosphates (or phosphorothioates, PS) are chemical compounds and anions with the general chemical formula (''x'' = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedr ...
s (Li2S–P2S5). * Solid polymer electrolyte (SPE) Solid
polymer electrolyte A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a ion-exchange membrane, semipermeable membrane generally made from ionomers and designed to proton conductor, conduct protons while acting as an electronic insulator and reactan ...
(SPE) are defined as a solvent-free salt solution in a polymer host material that conducts ions through the polymer chains. Compared to ISEs, SPEs are much easier to process, generally by solution casting, making them greatly compatible with large-scale manufacturing processes. Moreover, they possess higher elasticity and plasticity giving stability at the interface, flexibility and improved resistance to volume changes during operation. A good dissolution of Li salts, low glass transition temperature (Tg), electrochemical compatibility with most common electrode materials, a low degree of crystallinity, mechanical stability, low temperature sensitivity are all characteristics for the ideal SPE candidate. In general though the ionic conductivity is lower than the ISEs and their rate capability is restricted, limiting fast charging. PEO-based SPE is the first solid-state polymer in which ionic conductivity was demonstrated both through inter and intra molecular through ion hopping, thanks to the segmental motion of the polymeric chains because of the great ion complexation capability of the ether groups, but they suffer from the low room-temperature ionic conductivity (10−5 S cm−1) due to the high degree of crystallinity. The main alternatives to polyether-based SPEs are
polycarbonates Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily work ...
,
polyesters Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...
, polynitriles (e.g. PAN), polyalcohols (e.g. PVA),
polyamines A polyamine is an organic compound having more than two amino groups. Alkyl polyamines occur naturally, but some are synthetic. Alkylpolyamines are colorless, Hygroscopy, hygroscopic, and water soluble. Near neutral pH, they exist as the ammonium d ...
(e.g. PEI),
polysiloxane A silicone or polysiloxane is a polymer made up of siloxane (−R2Si−O−SiR2−, where R = organic group). They are typically colorless oils or rubber-like substances. Silicones are used in sealants, adhesives, lubricants, medicine, cooking ...
(e.g. PDMS) and
fluoropolymer A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases. The best known fluoropolymer is polytetrafluoroethylene under the brand name "Teflon ...
s (e.g. PVDF, PVDF-HFP). Bio-polymers like
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
,
chitosan Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked Glucosamine, D-glucosamine (deacetylated unit) and N-Acetylglucosamine, ''N''-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shell ...
and
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
are also gaining a lot of interest as standalone SPEs or blended with other polymers, on one side for their environmentally friendliness and on the other for their high complexation capability on the salts. Furthermore, different strategies are considered to increase the ionic conductivity of SPEs and the amorphous-to-crystalline ratio. With the introduction of particles as fillers inside the polymer solution, a composite polymer electrolyte (CPE) is obtained, the particles can be inert to the Li+ conduction (Al2O3, TiO2, SiO2, MgO, zeolite, montmorillonite, ...), with the sole purpose of reducing the crystallinity, or active (LLTO, LLZO, LATP...) if ISE's particles are dispersed and depending on the polymer/inorganic ratio the nomenclature ceramic-in-polymer and polymer-in-ceramic is often used.
Copolymerization In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...
,
crosslinking Cross-linking may refer to *Cross-link In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers ca ...
, interpenetration, and blending may also be used as polymer/polymer coordination to tune the properties of the SPEs and achieve better performances, introducing in the polymeric chains polar groups like
ethers In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...
,
carbonyls In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a ...
or
nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including met ...
s drastically improve the dissolution of the lithium salts.


Quasi-solid-state electrolyte

Quasi solid-state electrolytes (QSSEs) are a wide class of
composite Composite or compositing may refer to: Materials * Composite material, a material that is made from several different substances ** Metal matrix composite, composed of metal and other parts ** Cermet, a composite of ceramic and metallic materials ...
compounds consisting of a liquid
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 a solid matrix. This liquid
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 ...
serves as a percolating pathway of ion conduction while the solid matrix adds mechanical stability to the material as a whole. As the name suggests, QSSEs can have a range of mechanical properties from strong solid-like materials to those in a paste form. QSSEs can be subdivided into a number of categories including gel polymer electrolytes (GPEs), Ionogel electrolytes, and gel electrolytes (also known as "soggy sand" electrolytes). The most common QSSE, GPEs have a substantially different ionic conduction mechanism than SPEs, which conduct ions through the interaction with the substitutional groups of the polymer chains. Meanwhile, GPEs conduct ions mainly in the
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 ...
, which acts as
plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticiz ...
. The
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 ...
acts to increase the ionic conductivity of the electrolyte as well as soften the electrolyte for improved interfacial contact. The matrix of GPEs consist of a polymer network swollen in a solvent that contains the active ions (e.g., Li+, Na+, Mg2+, etc.). This allows for the composite to contain both the mechanical properties of solids and the high transport properties of liquids. A number of polymer hosts have been used in GPEs, including PEO, PAN,
PMMA PMMA may refer to: * para-Methoxymethamphetamine, a stimulant drug * Philippine Merchant Marine Academy The Philippine Merchant Marine Academy ( fil, Akademiya sa Bapor Pangkalakalan ng Pilipinas) also referred to by its acronym PMMA) is a ma ...
, PVDF-HFP, etc. The polymers are synthesized with increased porosity to incorporate solvents such as
ethylene carbonate Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the Cyclic compound, cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene car ...
(EC),
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 carbonat ...
(PC),
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 ...
(DEC), 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). Low molecular weight poly(ethylene glycol) (PEG) or other ethers or aprotic organic solvents with high dielectric constant like dimethylsulfoxide (DMSO) can also be mixed the SPE matrix. UV and thermal
cross-link In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...
ing are useful ways to polymerize in-situ the GPE directly in contact with the electrodes for a perfectly adherent interface. Values of ionic conductivity on the order of 1 mS cm−1 can be easily achieved with GPEs, as demonstrate the numerous research articles published. Emerging subclasses of QSSEs utilize various matrix materials and solvents. Ionogels, for example utilize
ionic liquid An ionic liquid (IL) is a salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of ...
s as a solvent that has improved safety including non-flammability and stability at high temperatures. Matrix materials in ionogels can vary from polymer materials to inorganic nano-materials. These matrix materials (as with all QSSEs) provide mechanical stability with a storage moduli up to 1 MPa or higher. Meanwhile, these materials can provide ionic conductivities on the order of 1 mS cm−1 without using flammable solvents. However, gel electrolytes (i.e. "soggy sand" electrolytes) can achieve liquid-like ionic conductivities (~ 10 mS cm−1) while being in the solid state. Matrix materials such as SiO2 nanoparticles are typically paired with low viscosity solvents (e.g.,
ethylene carbonate Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the Cyclic compound, cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene car ...
(EC)) to create a gel, whose properties can be modified based on the matrix loading. Matrix content ranging from 10 to 40 wt% can shift the mechanical properties of the electrolyte from a soft paste into a hard gel. However, a tradeoff between mechanical strength and ionic conductivity as one goes up with changing matrix content the other suffers. Despite this, matrix content in these materials can have added benefits including enhanced lithium transference number due to functionalized matrix materials. These new classes of QSSEs are an active area of research to develop the optimal combination of matrix and solvent.


Opportunities

The versatility and properties of the solid-state electrolyte widen the possible applications towards high energy density and cheaper battery chemistries that are otherwise prevented by the current state-of-the-art of
Li-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
. Indeed, by introducing a SSE in the battery architecture there's the possibility to use metallic lithium as anode material, with the possibility to achieve a high energy density battery thanks to its high specific capacity of 3860 mAh g−1. The utilization of a lithium metal anode (LMA) is prevented in a liquid electrolyte above all because of the dendritic growth of a pure Li electrode that easily cause short circuits after few cycles; other related issues are volume expansions, solid-electrolyte-interface (SEI) reactivity and 'dead' lithium. The usage of a SSE guarantees a homogeneous contact with the metallic lithium electrode and possess the mechanical properties to impede the uncontrolled deposition of Li+ ions during the charging phase. At the same time, a SSE finds very promising application in lithium-sulfur batteries solving the key issue of the polysulfide "shuttle" effect by blocking the dissolution of polysulfide species in the electrolyte that rapidly causes a reduction of capacity.


See also

*
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 ...
*
Li-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also see ...
* Lithium-sulfur battery *
Research in lithium-ion batteries Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and cost. Artifici ...


References


External links


Solid-state battery
Retrieved 2020-06-26. {{DEFAULTSORT:Solid-state electrolyte Chemistry Rechargeable batteries Battery types