The diversity of applications of graphene demonstrates its immense potential and makes it possible to envisage new horizons in fields such as optoelectronics and spintronics, according to our partner The Conversation.
Graphene is exploited for its status as a champion of electrical conductivity, but also for its low density and flexibility.
The analysis of this phenomenon was carried out by Thibaut Lalire, doctoral student in Materials Science at the Mines-Télécom Institute in Alès.
"Material of the 21st century", "revolutionary material", this is how graphene has been characterized since its discovery in 2004 by Konstantin Novoselov and Andre Geim. These two scientists' work on graphene won them the Nobel Prize in Physics in 2010, but what is it really, 17 years after this discovery?
Graphene is known worldwide for its remarkable properties, whether mechanical, thermal and electrical.
Its perfect honeycomb structure composed of carbon atoms is the reason why graphene is a performing material in many areas.
Its morphology, in the form of a thick sheet of the order of an atom, allows it to integrate the family of 2D materials.
Since its discovery, manufacturers have stepped up research into the material.
Various applications have emerged, in particular by exploiting the electrical performance of graphene.
Several sectors are targeted, such as aeronautics, automobiles and telecommunications.
Is there graphene on the plane?
Graphene is exploited for its status as a champion of electrical conductivity, but also for its low density and flexibility. These properties have enabled it to join the very closed club of materials used in the field of aeronautics.
Lightning and ice buildup on the hull are common problems encountered when airplanes are at high altitude.
The impact of lightning on a non-conductive surface causes serious damage, including ignition of the device.
The addition of graphene, due to its high electrical conductivity, dissipates this high energy current.
The design of the aircraft is designed so as to route the current as far as possible from risk areas, fuel tanks, control cables and thus avoid loss of control of the aircraft, or even explosion.
The history of graphene begins here © Umberto / Unsplash
A coating composed of a resin reinforced with graphene, one then speaks of “nanocomposite”, is used as a replacement for metallic coatings. Indeed, its low density makes it possible to obtain materials that are lighter than the original ones, limiting the mass of the device and therefore the fuel consumption. On the other hand, electrically conductive materials, necessary to dissipate the energy of lightning, have the drawback of reflecting electromagnetic waves preventing the use of this type of material for stealth applications in the military sector.
To remedy this defect, different forms of graphene have been developed to retain its electrical conductivity while improving stealth.
One of these new structures is “graphene foam”.
The wave penetrates the material, a phenomenon of reflections of the latter in all directions of space traps it and gradually attenuates its traces.
There is no possible return of the wave to the radar, the device becomes stealthy, and we speak of "electromagnetic shielding".
Graphene for energy storage
Graphene has also widely found its place in the field of electrical energy storage.
Graphene is an ideal candidate as an electrode for Li-ion batteries and supercapacitors. On the one hand because its electrical conductivity is high, on the other hand because its high specific surface (corresponding to the surface available on the graphene to accommodate the ions and promote the exchange of electrons between the graphene electrode and the lithium) allows to obtain a large "storage capacity". Indeed, a large number of ions can easily be inserted between the graphene sheets, which makes it possible to exchange more electrons with the current collector, increasing the storage capacity of electricity and therefore the autonomy of battery.The ease of the ions to insert into the graphene electrode and the high electrical conductivity of the latter (for rapid electron transfer) allow a much shorter discharge / charge cycle of the battery. The high conductivity of graphene makes it possible to deliver a large amount of energy in a very short time, thus increasing the power of the supercapacitors. Graphene is also a good thermal conductor, which limits the rise in temperature of the batteries by dissipating heat.which limits the rise in temperature of the batteries by dissipating heat.which limits the rise in temperature of the batteries by dissipating heat.
Electric batteries are increasingly ubiquitous in modern life. Graphene could improve their performance © Markus Spiske / Unsplash
On an industrial scale, there is already an external battery developed by Real Graphene, showing a full recharge of a cell phone in seventeen minutes.
In a completely different area, Mercedes is working on a prototype car with a battery made up of graphene electrodes, advertised with a range of 700 kilometers for a 15-minute recharge - at the moment these values seem surprising at first glance , especially for electric vehicles requiring batteries with high storage capacity.
Finding your place in electronics
Where graphene struggles to stand out from semiconductors is in the field of electronics. Its electronic properties - due to its "band structure" - make the control of electrons impossible and graphene then behaves like a semi-metal. As a result, the use of graphene for binary - digital - electronics remains complicated, in particular for transistors, which are rather made up of semiconductors.
To use graphene in a transistor, it is necessary to modify its band structure, which generally results in degrading its honeycomb structure and other electrical properties.
If one wishes to keep this 2D structure, it is necessary to change the chemical nature of the atoms making up the material by using, for example, boron nitride or transition metal dichalcogenides, which are also part of the large family of 2D materials.
Microscopy of the interface between graphene and boron nitride (h-BN) © Oak Ridge Natinal Laboratory / Flickr
If, however, one wishes to use graphene, one must aim for applications in which mechanical properties (flexibility) will also be sought, such as for sensors, electrodes and certain transistors reserved for analog electronics, such as graphene effect transistors. of field.
The telephony giants are also working on the development of flexible cell phone screens for better ergonomics.
The manufacture of the next quantum computers could well call upon materials called "topological insulators".
They are electrically conductive materials on the surface, but insulating at the core.
Research is currently increasing on the topological phase of graphene with electrical conduction only at the edges.
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The diversity of applications of graphene demonstrates the full potential of this material and makes it possible to envisage new horizons in different fields such as optoelectronics and spintronics.
This material has already been able to prove itself in the industrial environment without revolutionizing it at present.
However, ongoing research allows new fields of possible applications to be discovered each year.
At the same time, synthesis methods are constantly being developed to reduce the price of graphene per kilogram and allow a better quality material to be obtained.
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This analysis was written by Thibaut Lalire, doctoral student in Materials Science at the Mines-Télécom Institute in Alès.
The original article was published on The Conversation website.
Declaration of interests
Thibaut Lalire does not work, does not advise, does not own shares, does not receive funds from an organization that could benefit from this article, and has not declared any affiliation other than his research organization.
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