NiP nanoparticles encapsulated in lamellar carbon as high-performance anode materials for sodium-ion batteries

Abstract

Phosphate-based sodium anodes have been widely concerned for their high theoretical capacity, but their applications are limited by their significant volume evolution and poor conductivity. In order to buffer the volume variation of the phospho-based anode and improve its electrical conductivity, nickel phosphide (NiP) nanoparticles were uniformly encapsulated in the lamellar carbon shell (NiP@C) by solvothermal combined thermal decomposition reaction. Due to the filling of carbon between NiP particles, the volume expansion of NiP anode can be effectively alleviated during the cycling process, which makes NiP@C have excellent electrochemical performance. It can achieve the considerable capacity of 385.5 mAh/g at 50 mA g−1, and remain a capacity of 292 mAh/g after 100 cycles. Moreover, because carbon has better electron/ion conductivity, NiP@C exhibits faster kinetics than NiP.

Keywords

• Transition metal phosphide
• Carbon
• Sodium-ion battery
• Anode