As for hybrid supercapacitors, it is important to enhance the long cycling performance and high specific capacitance. In this paper, cobalt vanadate (Co2V2O7) hexagonal nanosheets on nickel foam are manufactured by a facile hydrothermal method and then transformed into numerous smaller size interconnected hierarchical nanosheets without any shape change via electrochemical reconstruction. Benefiting from the favorable architecture of hierarchical nanosheets via electrochemical reconstruction, the Co2V2O7 hexagonal nanosheet electrode exhibits a remarkable long cycling performance with 272% specific capacitance retention after 100,000 cycles at a current density of 5 A g-1 and then displays an increasing specific capacitance of 1834 F g-1 (tested at 1 A g-1). Furthermore, an aqueous hybrid supercapacitor device based on the Co2V2O7 hexagonal nanosheet electrode exhibits a high energy density of 35.2 Wh kg-1 at a power density of 1.01 kW kg-1 and an excellent cyclic stability with 71.4% capacitance retention after 10,000 cycles at 5 A g-1. These results offer a practicable pathway for enhancing the electrochemical properties of other metal oxides through electrochemical reconstruction.
Keywords: cobalt-based vanadate; electrochemical reconstruction; hierarchical nanosheets; hybrid supercapacitors; increased specific capacitance.