Yolk-shelled Ni2P@carbon nanocomposite as high-performance anode material for lithium and sodium ion batteries

Abstract Ni 2 P@Carbon (Ni 2 P@C) yolk-shell nanocomposite have been synthesized through a phosphorization-in-nanooctahedron combined with an annealing strategy. As an anode material, the as-obtained Ni 2 P@C nanocomposite presents excellent lithium/sodium storage performance for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). The significantly enhanced electrochemical properties are attributed to the electrochemical conductivity of the carbon shell and the yolk-shell nanoarchitecture, which provides buffer space to remit the volume changes of Ni 2 P during cycles process, enlarges the contact area of electrolyte/electrode and shortens the diffusion path of Li + (Na + )/electrons. As the anode in LIBs, the Ni 2 P@C nanocomposite delivers a discharge capacity of 512.3 mA h g −1 at 100 mA g −1 after 100 cycles. The specific capacity could be still 398.1 mA h g −1 at 1 A g −1 even after 1000 cycles. As an anode for SIBs, the reversible capacity of the Ni 2 P@C nanocomposite is 291.9 mA h g −1 at 100 mA g −1 after 300 cycles. The enhanced performance of Ni 2 P@C nanocomposite electrode can be ascribed to the advantageous structural design.