Electrochemical pseudocapacitance of Co/Co2P/CoP as electrode material for supercapacitor application

Abstract

It has become a consensus to study transition metal phosphides with abundant earth reserves and good electrochemical properties as electrode materials for supercapacitors. Among them, cobalt phosphide is particularly attractive because of its good electrical conductivity and theoretical specific capacity. Therefore, cobalt phosphide composites were prepared by hydrothermal reaction and phosphating reaction in this paper. Due to the synergistic effect of different components and the interfacial effect between the components, the ion transport and charge transfer kinetics of the prepared Co/Co2P/CoP electrode are both improved, which exhibits excellent electrochemical performance. At the current density of 1 A g−1, the prepared Co/Co2P/CoP electrode material has a specific capacitance of 193.3 mA h g−1, after 6000 cycles of charge and discharge at the current density of 2 A g−1, the specific capacitance maintains at 80 %. An asymmetric supercapacitor was assembled with the prepared material as the positive electrode and activated carbon as the negative electrode, which can provide an energy density of 37.87 W h kg−1 at a power density of 799.6 W kg−1. At the current density of 1 A g−1, the assembled supercapacitor can maintain 80 % of the initial specific capacitance after 5000 cycles. This provides ideas for future research on this type of energy storage materials.