Progress in graphene based supercapacitors

As one of the most promising type of energy storage devices, supercapacitors have attracted a great attention in recent years. Current focuses of research lie in the development of approaches to increase energy density and power density through increasing specific surface area, electrical conductivity and structural stability of capacitor materials. Graphene provides an ideal candidate capacitor material due toits large surface area, outstanding electrical conductivity and mechanical properties.However, restacking of graphene particles often occurs during fabrication processes, which reduces the actual specific surface area and ion conductivity. Keys to resolve this issue include the development of an appropriate fabrication method of graphene, modification of graphene surface with functional groups and formulation of graphene-based composite materials. This paper reports our recent work on graphene-based electrodes and their applications in electric double layer capacitors, pseudo- capacitors and asymmetric supercapacitors. Specific attention is paid to the fabrication of graphene gel film electrodes.