Nanocrystalline CoP thin film as a new anode material for lithium ion battery

Nanocrystalline CoP thin film was prepared by pulsed laser deposition (PLD) and the electrochemical investigation of CoP as anode material for lithium ion battery was reported for the first time. The reversible discharge capacity of CoP/Li cell cycled between 0.1–3.0 V was found in the range of 788.0–1055.7 mAh g−1 during the first 25 cycles. A reversible couple of redox peaks at 0.63 and 1.02 V was observed in the first cycle of cyclic voltammetry (CV) curves. Ex situ transmission electron microscopy (TEM) and selected-area electron diffraction (SAED) revealed the fully decomposition of CoP to Co/Li3P composite after discharging the CoP/Li cell to 0.1 V and the re-formation of CoP nanocrystalline structure after re-charging to 3.0 V, demonstrating a fully reversible conversion reaction mechanism between CoP and Co/Li3P composite. High utility of trivalent phosphorus benefits the reversibility and capacity of CoP and makes it potential anode material for future lithium ion battery.

► Nanocrystalline CoP thin films were prepared by pulsed laser deposition (PLD).
► High reversible discharge capacity of 839.1 mAh g−1 was achieved.
► Reversible conversion reaction mechanism to Co and Li3P was proposed for CoP.
► CoP is a potential anode material for future lithium ion battery.