High Performance Electrochemical Supercapacitors Based on Electrodeposited RuO2 on Graphene Sheet Electrodes

Ruthenium oxide (RuO2) electrode films with nanoscale morphologies were prepared on flexible Cu and Cu/graphene papers by using a cost-effective electrodeposition technique. Uniform spherical RuO2 grains formed on the graphene/Cu substrate while agglomerated RuO2 grains were observed on the Cu substrate. The RuO2/graphene/Cu electrode exhibited a high specific capacitance of similar to 930 F/g at a 5 mV/s scan rate, a comparably good electrochemical stability about 55% after 500 charge-discharge cycles, and a good rate capability. The specific capacitance of the RuO2/graphene/Cu electrode was of approximately three times more than that of the RuO2/Cu electrode (similar to 303 F/g), and the same ratio was maintained even for a 100 mV/s scan rate. The improved specific capacity of the RuO2/graphene/Cu was a result of the synergetic effect of the graphene and RuO2, which resulted in a large effective surface area and leads to an increase in the Li+2 ions and that are adsorbed and charge transport with greater ease.