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Abstract:In order to fabricate the composite electrodes of a supercapacitor, transition-metal oxide materials NiO and WO 3 were deposited on carbon electrodes by electron beam evaporation. The influences of various transition-metal oxides, scan rates of cyclic voltammograms (CVs), and galvanostatic charge/discharge tests on the characteristics of supercapacitor were studied. The charge/discharge efficiency and the lifetime of the composite electrodes were also investigated. It was found that the composite electrodes exhibited more favorable capacitance properties than those of the carbon electrodes at high scan rates. The results revealed the promotion of the capacitance property of the supercapacitor with composite electrode and the improving of the decay property in capacitance at high scan rate. In addition, the charge/discharge efficiency is close to 100% after 5000 cycles, and the composite electrode retains strong adhesion between the electrode material and the substrate.

In this study, the carbon electrode supercapacitors were fabricated using various specific surface areas of active carbon and contents of carbon black. The carbon black was added to increase conductivity of the carbon electrode. To find the optimal processing parameters of the carbon electrode, the effects of various specific surface areas of activated carbon and amounts of carbon black on the capacitive properties of the supercapacitor are investigated. The experimental results showed that the optimum carbon electrode can be obtained using mesocarbon microbeads with a high-specific surface area (2685 m 2 /g), a larger pore volume (0.6 cm 3 /g), and by adding 10 wt.% carbon black. The specific capacitance of the carbon electrode in 1 M KOH is 171.2 F/g.

In this study, xLi 2 O-(1−x)WO 3 powders were mixed with WO 3 and Li 2 O and pressed into target pellets to fabricate electrochromic films on indium tin oxide (ITO) glasses prepared by electron beam evaporation under the parameters of room temperature, and thicknesses of about 530 nm. It was expected that the amount of charge stored in the electrochromic devices (ECDs) could be enhanced by using the doping method in the cathode materials. The experimental results show that as the composition of Li 0.18 W 0.82 O 2.6 powder was formed, the optimal characteristics of ECD can be obtained. In which, as a voltage of 3.5 V was applied on ECD, a transmittance change (∆T%) of 53.1%, an optical density (∆OD) of 0.502, an intercalation charge (Q) of 12.9 mC/cm 2 and a coloration efficiency (η) of 41.6 cm 2 /C at a wavelength of 550 nm can be achieved. These results demonstrate that Li 2 O doping in WO 3 films could effectively improve the coloration and electrochromic properties of ECD devices.

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