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

Hybridizing Ni2P/graphene sheet composite is successfully accomplished via a one-pot solvothermal method. As anode materials for lithium-ion batteries, the Ni2P 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 Ni2P are significantly improved after the incorporation of graphene sheets. After 50 cycles, the Ni2P/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 Ni2P 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.