Co2P wrapped Co3O4 grass-like nanowires for improved electrochemical performance in supercapacitors

Abstract

As a new type of energy storage device, supercapacitor has gained a lot of popularity due to its superior power density than batteries. However, the poor energy density has become the impetus for the research of electrode materials with both high energy density and power density. In this paper, grass-like Co3O4@Co2P nanowires are prepared by a facile two-step method comprised of hydrothermal process and high temperature solid phase phosphating. As expect, the as-prepared sample shows an enhanced electrochemical performance. The specific capacity of Co3O4@Co2P can reach 652.1 C/g (1304.2 F/g) at a current density of 1 A/g, which is much higher than that of Co3O4 (228.5C/g). The rate capability and the cycling stability of Co3O4@Co2P are 64.3% at 10 A/g and 84% after 4000 cycles, respectively. Moreover, a hybrid supercapacitor (HSCs) has been assembled with Co3O4@Co2P as positive electrode and active carbon (AC) as negative electrodes. The maximum energy density and power density of HSC device are 31.3 Wh/kg and 8018.4 W/kg, respectively. Furthermore, the HSC device shows a cycling stability of 100% at the current density of 7 A/g after 10,000 cycles. These excellent properties show the potential applications of Co3O4@Co2P in the field of supercapacitors with high energy and power density.