Hydrothermal Synthesis of Hybrid Rod‐Like Hollow CoWO 4 /Co 1− x S for High‐Performance Supercapacitors

A rod‐like hollow cobalt tungstate/non‐stoichiometric cobalt sulfide (CoWO 4 /Co 1− x S) hybrid is successfully grown in situ on nickel foam through a simple two‐step hydrothermal process. Owing to the unique hollow structure, the as‐synthesized CoWO 4 /Co 1− x S hybrid electrode possesses a large surface area and delivers a high specific capacitance of 1894.5 F ⋅ g −1 at a current density of 1 A ⋅ g −1 . By using the CoWO 4 /Co 1− x S hybrid electrode as the anode and an activated carbon (AC) electrode as the cathode, an asymmetric supercapacitor of CoWO 4 /Co 1− x S//AC exhibits a high capacitance of 103.1 F ⋅ g −1 and high specific capacitance retention of 87.27 % after 5000 cycles. Furthermore, the asymmetric supercapacitor demonstrates a maximum power density of 4000 W ⋅ kg −1 at an energy density of 22.5 Wh ⋅ kg −1 . The superior performance of the device can be ascribed to distinctive structure and positive synergistic effects in the hybrid. The facile preparation process and excellent performance presented here indicate the CoWO 4 /Co 1− x S hybrid to be a promising candidate electrode material for supercapacitor applications.