Ni₂P/Graphene\nSheets as Anode Materials\nwith Enhanced Electrochemical Properties versus Lithium

Abstract

Hybridizing Ni₂P/graphene sheet composite\nis successfully\naccomplished via a one-pot solvothermal method. As anode materials\nfor lithium-ion batteries, the Ni₂P spheres with sizes\nof 10–30 nm can effectively prevent the agglomeration of graphene\nsheets. In turn, the graphene sheets with good electrical conductivity\nserve as a conducting network for fast electron transfer between the\nactive materials and charge collector, as well as buffered spaces\nto accommodate the volume expansion/contraction during cycling. The\ncyclic stability and rate capability of Ni₂P are significantly\nimproved after the incorporation of graphene sheets. After 50 cycles,\nthe Ni₂P/graphene sheet hybrid delivers a capacity of 450\nmA h g^–1 and 360 mA h g^–1 at a\ncurrent density of 54.2 and 542 mA g^–1, respectively.\nThe voltage hysteresis of Ni₂P with and without graphene\nsheets is also discussed. The incorporation of graphene sheets can\npartly decrease the voltage polarization, and modify the thickness\nof solid electrolyte interface (SEI) film.