Materials engineers at Monash University in Australia have devised a method of producing graphene supercapacitors that have the same energy density as the lead-acid battery under your car’s hood. Not only are these supercapacitors about 10 times more energy-dense than commercial devices, but the method of producing the graphene inside the supercapacitors seems to be novel as well. Graphene, however, could change all that. The amount of energy stored by an electrochemical capacitor is closely tied to the amount of charge-carrying electrolyte that contacts the electrodes. The higher the surface area of the electrodes, the more charge-carrying ions that can be adsorbed (attached) to the electrodes, thus storing more energy.
When fashioned into an electrochemical capacitor, this paper-like material has a volumetric energy density of almost 60 watt-hours per liter (Wh/l), which is just about comparable to a lead-acid battery. It retains about 90% of its capacitance after 50,000 charge/discharge cycles, and it even holds 90% of its charge after 300 hours.