关键词: 三氧化钨, 非对称超级电容器, 柔性, 能量密度

Abstract: The demand for a new generation of flexible, portable, and high-capacity power sources increases rapidly with the development of advanced wearable electronic devices. One dimensional (1D) nanowires structures have been demonstrated as one of the most ideal electrode materials in energy storage systems due to their advantages in both micorstructures and their high surface areas. Here we report a simple process for large-scale fabrication of self-standing composite film electrodes composed of WO₃ nanorods on carbon cloth. In order to improve the energy density of supercapacitor, we assembled an asymmetric supercapacitor using WO₃ nanorods and activated carbon cloth as positive and negative electrodes, respectively. The scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the morphology and structure of the electrode materials, respectively. In addition, cyclic voltammetry (CV), galvanostatic charge-diacharge (GCD) test, and electrochemical impedance spectroscopy (EIS) were employed to study the electrode materials in a three-electrode system. It was found that the WO₃ nanorods exhibited attractive electrochemical performance as well as remarkable flexibility with the high areal capacitance of 3347 mF·cm^-2 at 5 mA·cm^-2. In addition, to improve the electrochemical performance of activated carbon cloth by introducing function groups onto its surface for producing pseudocapacitance and increasing surface area by electrochemically oxidizing CC in the mixed acid solution, it was also shown the high areal capacitance of 1160 mF·cm^-2 at 7 mA·cm^-2. This method was simpler and more effective compared with the previous strategies for activating carbon materials. The as-fabricated asymmetric supercapacitor based on WO₃/carbon cloth exhibited high areal capacitance of 58.96 F·cm^-2 at 61.9 mA·cm^-2, high energy density of 20.36 mWh·cm^-2 at 0.48 W·cm^-2 with the operation voltage window expanding to 0 ~ 1.6 V, and excellent lifespan after 3000 cycles. This work opens up a novel, low-cost route to design advanced integrated-array and high performance electrode materials for portable supercapacitor application on a large scale.

Key words: WO₃, asymmetric supercapacitor, flexible, energy density