Metallic nickel–cobalt phosphide/multilayer graphene composite for high-performance supercapacitors†
A facile and low-cost method for preparing a nickel–cobalt phosphide/multilayer graphene (MLG) (NiCoP/MLG) composite was developed in this study using a new strategy. NiCoP/MLG was prepared through calcination of NiCo-benzoate layered double hydroxide (NiCo-B-LDH) to obtain NiCoO2/MLG first followed by phosphorization to obtain the composite of NiCoP/MLG. Here, NiCo-B-LDH served as a self-sacrificing template. The obtained porous flower-like NiCoP/MLG was tested as a material for supercapacitor electrodes, which exhibited excellent electrochemical performance in terms of specific capacitance (1419.6 F g−1 at 1 A g−1), durability at high current density and long-term operation with 91.7% capacitance retention after more than 3000 cycles at a current density of 5 A g−1. Moreover, the symmetrical supercapacitor based on NiCoP/MLG delivered a high energy density of 32.19 W h kg−1 at a power density of 741.65 W kg−1. Therefore, the as-prepared NiCoP/MLG could serve as a high-performance supercapacitor electrode material.