Electrochemical properties and lithium-ion storage mechanism of LiCuVO4 as an intercalation anode material for lithium-ion batteries

Abstract

LiCuVO₄ with distorted inverse spinel structure is prepared by solid-state reaction and comprehensively examined as an intercalation anode material by means of cyclic voltammograms (CV), galvanostatic charge–discharge profiles, rate performance, and electrochemical impedance spectroscopy (EIS). LiCuVO₄ shows a stable capacity of 447 mA h g⁻¹ under 3–0.01 V at the current density of 200 mA g⁻¹, and the capacity retention reaches 91% after 50 cycles. At high cutoff voltage, between 3 and 0.2 V, LiCuVO₄ also delivers an average reversible capacity of 200 mA h g⁻¹ at a current density of 2000 mA g⁻¹, higher than the performance of the newly reported Li₃VO₄. Moreover, the lithium ion storage mechanism for LiCuVO₄ is also explained on the basis of the ex situ X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) at different insertion/extraction depths. While being discharged to 0.01 V, LiCuVO₄ decomposes into Li₃VO₄, whose surface is coated by Cu nanoparticles spontaneously. Interestingly, Li ions are suggested to be inserted into Li₃VO₄ in the subsequent cycles due to the intercalation mechanism, and Cu nanoparticles would not contribute to the reversible capacity. Our findings provide a strong supplemental insight into the electrochemical mechanism of the anode for lithium-ion batteries. In addition, LiCuVO₄ is expected to be a potential anode material because of its low cost, simple preparation procedure, good electrochemical performance and safety discharge voltage.