High-energy-density nonaqueous MnO2@nanoporous gold based supercapacitors†
The lack of sufficient energy density has been the key obstacle that hinders the wide range of applications of electrochemical supercapacitors. Improving both specific capacitance and stable potential window appears to be the only route to achieve high-energy-density supercapacitors. Although nonaqueous electrolytes can provide large working potential windows, the pseudocapacitance of active materials is usually much lower in nonaqueous electrolytes than in aqueous solutions, resulting in low energy density. In this study we report novel nonaqueous MnO2@nanoporous gold based supercapacitors. The capacitive performances of MnO2 in nonaqueous electrolytes are dramatically improved by nanoporous gold. The excellent electronic conductivity, rich porous structure and large surface area of the nanoporous electrodes give rise to low internal resistance, good ionic contact and thus enhanced redox reactions for high specific capacitance of MnO2 in non-aqueous electrolytes with a large working potential window.