RGO‐Modified CoWO4 Nanoparticles as New High‐Performance Electrode Materials with Enhanced Electrochemical Performances for Supercapacitors

Abstract

A facile one‐pot hydrothermal method is provided for synthesis of the reduced graphene oxide‐cobalt tungstate (rGO@CoWO4) nanocomposites with the enhanced electrochemical performances for supercapacitors (SCs). The resulting nanocomposites are comprised of CoWO4 nanospheres that are well anchored on graphene sheets by in situ reducing. The BET‐specific surface area of CoWO4, rGO@CoWO4 nanocomposites are 101 and 167 m2 g−1, respectively. The electrochemical evaluations are carried out in a 1 M KOH solution as the electrolyte. The hybrid electrode shows excellent specific capacitance of 1145 F g−1 at a current density of 1 A g−1 with superior rate capability and satisfactory cycling stability (97.2% capacitance preserved after 10 000 cycles). The good electrochemical performance can be attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of rGO and CoWO4 nanospheres. Moreover, the cyclic stability tests demonstrat capacitance retention of about 97.2% after 10 000 cycles, suggesting the potential application of rGO@CoWO4 nanocomposites in energy storage devices. The asymmetric SCs assembled with rGO@CoWO4 and activated carbon exhibit high energy density (39.1 Wh kg−1) and power density (631.2 W kg−1 at 1 A g−1), with remarkable cycle life (96.7% over 10 000 cycles) while still maintaining 24.5 Wh kg−1 at an even higher power density of 5098 W kg−1. The above results indicate that the hybrid rGO@CoWO4 electrodes synthesized by this approach would be a promising candidate for practical application of high‐performance SCs.