Enhanced electrochemical performance of cobalt vanadium oxide supercapacitors through optimized reduced graphene oxide composite

Abstract

This study illustrates the strategic improvement of cobalt vanadium oxide (CVO) electrodes for supercapacitor applications by integrating reduced graphene oxide (rGO) through a hydrothermal synthesis method. The optimized CVO-12 mg-rGO composite had a specific capacitance of 327 F/g at 2 mA/cm2, an energy density of 11.34 Wh/kg, and a power density of 124 W/kg. This was better than pristine CVO and better than several other vanadate-based electrodes that have been reported. BET analysis showed that rGO exfoliation increased the surface area (16.26 m2/g) and made the pores easier to get to. EIS showed that the charge transfer resistance was lower (1.6 Ω). The made-up asymmetric device (CVO-12 mg-rGO//AC) showed that it could be used in real life by having a specific capacitance of 25.92 F/g, an energy density of 11.65 Wh/ kg, a high coulombic efficiency of about 99.9 %, and a great cycling retention of 70 % after 4.7 k cycles. These results show that combining pseudocapacitive CVO and conductive rGO in a synergistic way greatly improves the transport of electrons and ions, electrochemical reversibility, and long-term stability. The results show that CVO@rGO composites are promising electrodes for next-generation high-performance supercapacitors. © 2025 Elsevier B.V., All rights reserved.