Ni₂P/Graphene Sheets as Anode Materials with Enhanced Electrochemical Properties versus Lithium

Abstract

Hybridizing Ni 2 P/graphene sheet composite is successfully accomplished via a one-pot solvothermal method. As anode materials for lithium-ion batteries, the Ni 2 P spheres with sizes of 10–30 nm can effectively prevent the agglomeration of graphene sheets. In turn, the graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during cycling. The cyclic stability and rate capability of Ni 2 P are significantly improved after the incorporation of graphene sheets. After 50 cycles, the Ni 2 P/graphene sheet hybrid delivers a capacity of 450 mA h g –1 and 360 mA h g –1 at a current density of 54.2 and 542 mA g –1, respectively. The voltage hysteresis of Ni 2 P with and without graphene sheets is also discussed. The incorporation of graphene sheets can partly decrease the voltage polarization, and modify the thickness of solid electrolyte interface (SEI) film.