Unraveling the regulation rules of vanadium-site cation substitution for Na₃V₂(PO₄)₃ cathode materials toward high energy density sodium-ion batteries

NASICON-type Na₃V₂(PO₄)₃ (NVP) materials are seen as highly promising cathode materials in the field of sodium-ion batteries due to their low cost, a solid three-dimensional skeleton and good theoretical capacity, as well as high ionic conductivity. Nevertheless, the problem of low intrinsic electronic conductivity and energy density has limited the practical application of the materials. To address this issue, the relevant research team has successfully achieved remarkable research results through unremitting exploration and practical innovation. In this work, the crystal structure, ion migration mechanism and sodium storage mechanism of NVP cathode materials are systematically reviewed, with a focus on summarizing the latest progress of V-site doping modification research, classifying and exploring V-site doping from the perspectives of electronic structure, lattice strain and entropy, and briefly describing the optimization mechanism of V-site doping on electrochemical performance. In addition, the challenges and prospects for the future development of NVP cathode materials are presented, which are believed to provide new thinking for the design and development of high-performance NVP cathode materials and contribute to the large-scale application of sodium-ion batteries.