CoP Nanoprism Arrays: Pseudocapacitive Behavior on the Electrode-Electrolyte Interface and Electrochemical Application as an Anode Material for Supercapacitors

Abstract The self-supported transition metal phosphide with specific morphology and architecture has been investigated extensively due to excellent conductivity, stability, and morphologic diversity. In the work, cobalt phosphide with special nanoprism arrays in-situ grown on the nickel foam skeleton forms a typical three-dimensional open structure. It exhibits notable electrochemical performance when employed as an anode in a single electrode system, which owns a high mass specific capacitance (1349 F g-1 at the current density of 1 A g-1, which is the highest compared with that in the extant literature), good rate capacity and cycle stability. Besides, pseudocapacitive contribution to the entire capacity is up to about 77%, revealing the nature of high mass specific capacitance of the as-prepared CoP@NF as the working electrode. Furthermore, an asymmetrical supercapacitor device has been fabricated using CoP@NF as an anode and CMK-3@NF as a cathode. It can deliver a high power density of 325 W kg-1 at the energy density of 24 Wh kg-1 and the specific capacitance retention of about 93% after 5000 cycles. The results demonstrate that CoP@NF with special nanoprism arrays is a promising potential candidate as the electrode material of supercapacitors and other energy-storing applications.