Performance Of Oxide Composite Electrode Materials For Supercapacitor

A supercapacitor (also known as electrochemical capacitor or ultracapacitor) is a new energy storage device that combines the benefits of traditional capacitor and battery. It can provide greater energy density than traditional capacitors and higher power density than batteries. At the same time, it have long cycle life, wide operating temperature, fast charge and discharge feature and maintenance-free, friendly environmentally advantages, which have found broad application prospects in the power system such as hybrid electric vehicles, military, industrial, and other fields etc. In this paper, the composite electrode materials of zinc oxide and cobalt oxide with aluminum ion, active carbon, and polyaniline were prepared, and then their applications for supercapacitor were researched. The concrete contents are as followed:1. Zinc oxide with aluminum ion and cobalt ion composites was prepared by hydrothermal method respectively. The morphology and structure of the obtained composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behaviors were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GC) and electrochemical impedance spectrometry (EIS) experiments in a 6 mol/L KOH electrolyte within the potential of 0-0.4 and 0-0.5 V. When the content of aluminum ion and cobalt ion were 3% and 4%, the composites exhibit the highest capacitance values of 19 F/g and 37.5 F/g at a scan rate of 20 mV/s, which were 2 times and 5.8 times higher than pure zinc oxide (6.5 F/g). And a capacitance loss of 13% and 2% were observed during the first 1000 cycles.2. Zinc oxide/active carbon composite electrode material was prepared and the morphology and structure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behaviors were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GC) and electrochemical impedance spectrometry (EIS) experiments in a 6 mol/L KOH electrolyte within the potential of 0-0.4 V. The specific capacitance can reach 79.2 F/g at a mass ratio of zinc oxide to active carbon of 1:1, which was 12.2 times higher than pure zinc oxide (6.5 F/g). Additionally, a capacitance loss of 7.5% was observed during the first 1000 cycles.3. Cobalt oxide and Zinc oxide/Cobalt oxide composite electrode material was prepared by hydrothermal method. The electrochemical behaviors were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GC) and electrochemical impedance spectrometry (EIS) experiments in a 6 mol/L KOH electrolyte within the potential of 0.1-0.8 V. The specific capacitance can reach 143.7 F/g. Additionally, a capacitance loss of 6% was observed during the first 1000 cycles.4. Hexagonal and porous flake-like structure of zinc oxide and zinc oxide/polyaniline materials were prepared through sol-gel method and inverted emulsion polymerization method respectively. The specific capacitance can reach 258 F/g at a mass ratio of ZnO to PANI of 1:4 in a 6 mol/L KOH electrolyte within the potential of-0.2-0.5V.5. Cobalt oxides with different heat temperature were prepared by hydrothermal method. The specific capacitance can reach 158 F/g at a heat temperature of 400℃in a 6mol/L KOH electrolyte within the potential of 0-0.7V. And then, cobalt oxide (400℃)/polyaniline composite were prepared. The electrochemical measurements revealed that specific capacitance can reach 357 F/g at a mass ratio of cobalt to polyaniline of 1:2, which was much higher than either pure cobalt oxide (158 F/g) or pure polyaniline (156 F/g).