Hierarchical Nickel–Cobalt Phosphide/Phosphate/Carbon Nanosheets for High-Performance Supercapacitors

Abstract

Transition-metal phosphates/phosphides, as an emerging kind of prominent electroactive material, have drawn extensive attention in the fields of energy conversion and storage owing to their high electrical conductivity and metal-like properties. Herein, we report the preparation of hierarchical Ni–Co–P/POx/C nanosheets in a controllable manner using nickel–cobalt metal–organic framework (NiCo-MOF) as the precursor, followed by a low-temperature phosphating method. Electrochemical studies show that the Ni–Co–P/POx/C nanosheets exhibit good reversible capacity and excellent rate capability and possess capacities of 583 and 365.7 C g–1 at 1 and 30 A g–1, respectively. Furthermore, a two-electrode device assembled by Ni–Co–P/POx/C and reduced graphene oxide shows a peak energy density of 37.59 Wh kg–1 at a power density of 800 W kg–1 and a stable capacitive performance. These results indicate that the obtained bimetallic Ni–Co–P/C is a promising anode material for capacitive energy storage devices.