Bi2O3 with activated carbon composite as a supercapacitor electrode

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 332.6 F g−1 in 6 M KOH by chronopotentiometry at a specific current of 1 A g−1 and the specific capacitance is more than 3 times larger than that of activated carbon (106.5 F g−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.