Copper hydroxyphosphate Cu2(OH)PO4 as conversion-type anode material for lithium-ion batteries

Abstract

The copper hydroxyphosphate Cu₂(OH)PO₄ was synthesized under mild hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. The electrochemical performance of Cu₂(OH)PO₄ as anode material for lithium-ion batteries (LIBs) was investigated. The Cu₂(OH)PO₄ anode delivers a capacity of 741.1 mAh g⁻¹ at 0.1 A g⁻¹ over 300 cycles. The electrochemical and structural analyses suggest that the Cu₂(OH)PO₄ anode undergoes the conversion reaction with Li⁺ ions during lithium storage process. The in situ generated ion conductive Li₃PO₄ is much beneficial to enhance Li⁺ diffusion that leads to good rate capability and cycling stability. Besides the diffusion-controlled process, the surface capacitive effect also considerably contributes to the achieved capacity of the electrode. The results indicate that the polyanionic metal phosphate compounds are potential candidates for conversion-type anode materials for LIBs.