Bi2O3 with activated carbon composite as a supercapacitor electrode

Abstract

To improve the capacitance of activated carbon (AC) supercapacitors, the activated carbon–bismuth oxide (AC–Bi2O3) composite was synthesized by vacuum impregnation and roasting process. The morphology and phase structure of the AC–Bi2O3 composite was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). The electrochemical performance (cyclic voltammetry (CV), galvanostatic charge discharge tests and electrochemical impedance spectroscopy (EIS)) of the AC electrode and the AC–Bi2O3 electrode was characterized on the electrochemical workstation. It was found that the capacitance of AC–Bi2O3 composite is 332.6Fg−1 in 6M KOH by chronopotentiometry at a specific current of 1Ag−1 and the specific capacitance is more than 3 times larger than that of activated carbon (106.5Fg−1) at the same condition. In addition, the composite also displays a low resistance and a good stability. These results show that AC–Bi2O3 composite is a very promising electrode material for high-performance supercapacitors.