Optimization strategies for polyanion batteries: from the perspective of ion transport and electronic conduction

Polyanion electrode materials have garnered widespread attention due to their stable XO₄/P₂O₇ framework, tunable induction effect, and excellent thermal stability. However, their development is hindered by low intrinsic electronic conductivity, slow solid-state ion diffusion, and adverse interfacial side reactions. Unlike focusing on single material systems, single alkali metal ions, or isolated modification strategies, the uniqueness of this review lies in constructing a cross-system analysis framework centered on transport kinetics. It is the first to systematically compare Li⁺, Na⁺, and K⁺ polyanion systems from the same perspective. This review focuses on the interactions between electron transport, ion insertion, and interfacial coupling, summarizing the structural characteristics of major polyanion systems. It further explores mechanisms to enhance performance through carbon coating and conductive network construction, element doping, heterostructure engineering, nanoscale design, lattice and defect engineering, electrolyte solvation regulation, and CEI/SEI modulation. It combines first-principles calculations with experimental optimization to provide theoretical support for mechanism analysis. This review emphasizes that the development of high-performance polyanion electrodes requires achieving structural stability, continuous electronic conduction paths, low-energy-barrier ion transport channels, and stable interfacial reactions simultaneously. Additionally, this article points out that future development needs to address practical constraints such as cost, scalability, environmental impact, and commercial feasibility; by deeply studying the collaborative design criteria of electron transport, ion transport, and interfacial coupling, it is expected to promote the leap from laboratory to engineering application design for polyanion electrode materials in low-cost, long-lasting, fast-charging, and low-temperature energy storage applications.