Graphene foam to prevent the batteries from overheating

Making the most of the potential of a drums is a real compromise of extreme constraints. Among these is the outside temperature. When it is too low, or too high, performance deteriorates and autonomy too. It is for this reason that it is recommended not to solicit batteries lithium-ion only over a current temperature range of 0 to 45 ° C and in particular when it comes to recharging them. Since electronic devices heat themselves, usually passive systems are used for conduction and convection to maintain an optimal temperature. This is all the more true for drones, where the electric cars whose batteries are highly stressed.

To sort out these hot and cold stories, researchers from thePurdue University in the United States have bet on material magical that is graphene. The properties of graphene make it both an excellent conductor for evacuating the heat, but that it can also serve as a formidable insulator. For this, they designed a kind of mousse composed of a superposition of thin sheets of carbone the thickness of a atom.

A variable thermal switch

The mousse is placed between the drums and one radiator. When it’s cold, the 1.2-millimeter thick foam acts as an insulator thanks to its air cells.air. But when the temperature rises, the foam gradually compresses. During this heat-dependent compression, its thermal conduction capacities increase. In the end, the foam can settle to a maximum of 0.2 millimeters in thickness. Its conduction is then multiplied by eight. With this system which makes one think of that of a thermal switch, but with the variable and progressive side in addition, graphene foam can conduct heat as well as conserve it. The researchers tested the process over a temperature range of 0 to 30 ° C. The graphene foam then made it possible to retain heat in a sufficiently stable manner so that the battery could continuously deliver its best performance.