![Graphene foam Ni SEM](https://upload.wikimedia.org/wikipedia/commons/8/85/Graphene_foam_Ni_SEM.jpg)
Graphene foam is a solid, open-cell
foam
Foams are materials formed by trapping pockets of gas in a liquid or solid.
A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...
made of single-layer sheets of
graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. .
[ ]
Supplement
It is a candidate substrate for the
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 ...
of
lithium-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 ...
.
Synthesis
The foam can be manufactured using
vapor deposition
Vacuum deposition is a group of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures well below atmospheric pressure (i.e., vacuum). The deposited layers can r ...
to coat a
metal foam
Regular foamed aluminium
A metal foam is a cellular structure consisting of a solid metal (frequently aluminium) with gas-filled pores comprising a large portion of the volume. The pores can be sealed (closed-cell foam) or interconnected (open-c ...
, a three-dimensional mesh of metal filaments. The metal is then removed.
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]
Applications
Electrode
A physically flexible battery was created using the foam for electrodes. The anode was made by coating the foam with a lithium-titanium compound () and the 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 ...
by coating the foam with . Both electrodes were lightweight and their large surface area provided high 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 ...
of 110 Wh/kg, comparable to commercial batteries.[
]Power density
Power density is the amount of power (time rate of energy transfer) per unit volume.
In energy transformers including batteries, fuel cells, motors, power supply units etc., power density refers to a volume, where it is often called volume p ...
was much greater than a typical battery. At a rate that completely discharged the material in 18 seconds, power delivered was 80 percent of what it produced during an hour-long discharge. Performance remained stable through 500 charge/discharge cycles.[
]
Support
In 2017 researchers used carbon nanotubes
A scanning tunneling microscopy image of a single-walled carbon nanotube
Rotating single-walled zigzag carbon nanotube
A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometers.
''Single-wall carbon nan ...
to reinforce a foam. The latter material supports 3,000 times its own weight and can return to its original shape when unweighted. Nanotubes, a powdered nickel catalyst and sugar were mixed. Dried pellets of the substance were then compressed in a steel die in the shape of a screw. The nickel was removed, leaving a screw-shaped piece of foam. The nanotubes' outer layers split and bonded with the graphene.
See also
* Aerographene Aerographene or graphene aerogel is, , the least dense solid known, at , less than helium. It is approximately 7.5 times less dense than air. Note that the cited density does not include the weight of the air incorporated in the structure: it does n ...
* 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 ...
* Foam
Foams are materials formed by trapping pockets of gas in a liquid or solid.
A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...
References
Further reading
*
Lithium-ion batteries
Graphene
Electrodes
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