Graphene Hydrogels Deposited in Nickel Foams for High-Rate Electrochemical Capacitors

Graphene hydrogel/nickel foam composite electrodes for high‐rate electrochemical capacitors are produced by reduction of an aqueous dispersion of graphene oxide in a nickel foam (upper half of figure). The micropores of the hydrogel are exposed to the electrolyte so that ions can enter and form electrochemical double‐layers. The nickel framework shortens the distances of charge transfer. Therefore, the electrochemical capacitor exhibits highrate performance (see plots).