Fabrication of highly ordered porous nickel phosphide films and their application as anode for lithium ion batteries

Highly ordered porous Ni₃P film was successfully prepared by electrodeposition through self-assembled monodisperse polystyrene sphere template on copper substrate. The microstructure and morphology of the Ni₃P film were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). The structure of the as-prepared Ni₃P film is tetragonal with space group of I4 (a = b = 8.952 A¿, c = 4.388 A¿, JCPDS No. 34-0501). The pores in the film are about 800 nm in diameter and the film is about 1 ¿m in thickness. As anode for lithium ion batteries, the porous Ni₃P film can exhibit reversible discharge capacity above 350 mAh·g^-1 even after 50 cycles. Compared to the dense electrodeposited film, the improved electrochemical performance of ordered porous Ni₃P film is attributed to the better contact between Ni₃P and electrolyte, which provides more sites for Li⁺ accommodation, shortens the diffusion length of Li⁺ and enhances the reactivity of electrode reaction.