Preparation and Electrochemical Studies of Fe²⁺ and Cl^– Codoped Li₃V₂(PO₄)₃ with Superior Cyclic Stability and Rate Performance

Monoclinic Li3V2(PO4)3 (LVPO) features a three-dimensional channel structure, which provides a high theoretical specific capacity and average operating voltage, making it a promising candidate for lithium-ion batteries. However, LVPO suffers from low inherent electronic conductivity, which significantly restricts its high-rate performance in practical applications. In this study, we synthesize Li3V2–xFex(PO4)3–xCl3x (LVFexPOCl3x) codoped with Fe2+ and Cl–. The optimized sample demonstrates excellent rate performance and cycle stability. Notably, LVFe0.05POCl0.15 delivers a high capacity of ∼114.7 mAh g–1 at a rate of 10 C, and the capacity retention rate of LVFe0.05POCl0.15 after 1000 cycles is 87%, significantly outperforming that of LVPO (77%). In addition, LVFe0.05POCl0.15 exhibits outstanding electrochemical properties within the temperature range of 25–65 °C. This work highlights pathways for the development of stable LVPO cathodes through a cost-effective fabrication method.