Facile synthesis of NiCoP nanosheets on carbon cloth and their application as positive electrode material in asymmetric supercapacitor

Abstract

Transition metal phosphides (TMPs) are regarded as reliable supercapacitor electrode materials due to its high conductivity and excellent chemical activity. In this work, NiCo-LDH was synthesized via electrode position techniques, followed by one-step phosphating to convert the hydroxide into a phosphide. The obtained NiCoP shows 3D porous nanosheet stack structure, which provides a larger specific surface area and more active sites. The as-fabricated electrode exhibits good electrochemical performance with high specific capacitance (1142.84 F g−1 at 1 A g−1), good rate capabilities (62.07% of the initial specific capacitance at 10 A g−1), and outstanding cycle stability (maintains 74.5% of initial capacitances after 5000 cycles at 10 A g−1). Owning to superior electrical conductivity and excellent redox activity of phosphide, its voltage window and cycle stability are significantly improved compared with NiCo-LDH. In addition, NiCoP was used as the positive electrode and rGO as the negative electrode to fabricate the NiCoP//rGO asymmetric supercapacitor, which delivers a voltage window of 1.5 V and a high energy density of 14.7 Wh kg−1 at a power density of 753.6 W kg−1.