Researchers at Chalmers University, Sweden, have developed a new type of battery using a graphene sponge. A thin slice of porous graphene aerogel is placed in the battery and then soaked in a sulphur-rich catholyte solution. The result is a lighter battery that can hold 7 or 8 times more charge for its weight than a lithium-ion one.
Batteries typically contain four parts: anode and cathode electrodes, an electrolyte to allow ions to move back and forth, and a separator, which prevents the electrodes from touching. Researchers had previously found a way to blend the cathode and electrode into a sulphur-rich solution called a catholyte. Using sponge-like graphene, large amounts of the solution are trapped, which gives a better energy density, 1,000-1,500 watts per kg compared to the 350 watt maximum of lithium-ion.
The technology could have several advantages over lithium-ion. The higher energy density should allow them to run longer between charges and they’re lighter.
Aleksander Matic, Professor at Chalmers Department of Physics, adds, “Furthermore, sulphur is cheap, highly abundant, and much more environmentally friendly. Lithium sulphur batteries also have the advantage of not needing to contain any environmentally harmful fluorine, as is commonly found in lithium ion batteries.”
There is some way to go before the technology becomes commercially viable. Battery life is lower than a lithium-ion battery, the prototype managed just 350 cycles before its capacity had dropped to 85 per cent. The manufacturing process also needs to be designed, as they’re produced in a quite different way from lithium-ion.
However, the low weight, energy density and lower environmental impact should make this a technology worth exploring.