Electrochemical performance of MoO3-RuO2/Ti in H2SO4 electrolyte as anodes for asymmetric supercapacitors

Abstract

Based on the corrosion and low decomposition voltage of acid solutions, many electrodes are limited in the fields of supercapacitors. MoO3 has a wide potential window from -1.0 to 0.8 V in acid solution in theory. But there are very few reports of MoO3 used as anode due to its poor cycle stability and low electrochemical performance under a negative potential in most electrolyte solutions. The MoO3-RuO2/Ti was prepared by thermal decomposition. The phase structure, pore size, microstructure and capacitive characteristics of the MoO3-RuO2/Ti with different content of RuO2 were analyzed in detail by XRD, SEM, EDS, XPS, BET and electrochemical tests. The amorphous RuO2 was evenly distributed in MoO3. Remarkably, a high surface area and total pore volume were achieved by adding 5mol% RuO2 into MoO3, which resulted in a specific capacity of 639 C g–1 at 1A g–1. The poor cycle stability and electrochemical performance of MoO3 under a negative potential were greatly improved by adding RuO2. MoO3-RuO2/Ti used as anode in H2SO4 electrolyte was firstly discussed. The working voltage of MoO3-RuO2/Ti for anode was -0.35 to 0 V and had an excellent specific electrochemical performance. Asymmetric supercapacitor (ASC) was constructed using the MoO3-RuO2/Ti as anode and the IrO2-ZnO/Ti as cathode in H2SO4 electrolyte, which could be run under the potential range from 0 to 1.5 V. When the power density of asymmetric supercapacitor was 932 W kg–1 and 6580 W kg–1, the energy density was 80.5 Wh kg–1 and 57.4 Wh kg–1, respectively. Asymmetric supercapacitor with the MoO3-RuO2/Ti as anode and the RuO2-ZnO/Ti as cathode was also successfully assembled.