Construction of carbon-coated nickel phosphide nanoparticle assembled submicrospheres with enhanced electrochemical properties for lithium/sodium-ion batteries.

A hybrid based on nickel phosphide nanoparticle assembled submicrospheres coated with a glucose-derived carbon shell is synthesized from Ni-glycerate precursors through a carbon coating route and a subsequent calcination-phosphatization approach. Characterization results indicate that the synthesized submicrospheres have a diameter of ∼500 nm and are composed of nanoparticles as subunits with sizes ranging from 30 to 40 nm. Each sphere and its subunits are coated by a continuous carbon coating shell. The electrochemical performance of the material as an anode for reversible energy storage is investigated and evaluated. A comparative study of the lithium/sodium storage properties between the hybrid and pure nickel phosphide is carried out. The electrochemical results demonstrate that the hybrid fabricated electrode is a highly attractive anode for lithium- and sodium-ion batteries, exhibiting much better lithium/sodium storage properties compared to the nickel phosphide submicrospheres of the same construction. The reasons for the enhanced energy storage performance of the submicrospheres are explored by a series of comparison experiments based on morphology, structure, electrical conductivity, and kinetic property.