NaVPO₄F is attracting extensive attention as cathode material for sodium ion batteries owing to its advantages of stable structure, high voltage platform and high theoretical capacity. However, the poor electrical conductivity of NaVPO₄F hinders its practical application. In this work, we propose a facile strategy to construct abundant oxygen vacancies in NaVPO₄F@C by the introduction of Cr²⁺ to solve the problem associated with poor electronic conductivity. Density functional theory calculations and experimental studies indicate that the suitable Cr doping and abundant oxygen vacancies can significantly promote the electronic conductivity and Na-ion diffusion kinetics. Benefiting from the synergistic effects, the optimized Cr-doped NaVPO₄F@C displays a high capacity of 121.3 mA h g⁻¹ at 1 C and a high rate capacity of 98.8 mA h g⁻¹ at 10 C with the capacity retention of 79.3% after 4000 cycles. Moreover, it also shows outstanding cycling performance and rate capability when assembled into full batteries (NaTi₂(PO₄)₃@G film as the anode). This facile method proposed in our work may present a feasible approach to design the oxygen vacancies into other cathode materials for greatly improving the performance of sodium ion batteries.

NaVPO ₄ F具有结构稳定、电压平台高、理论容量高等优点，作为钠离子电池正极材料受到广泛关注。_{然而，NaVPO 4} F较差的导电性阻碍了其实际应用。在这项工作中，我们提出了一种简单的策略，通过引入 Cr ²⁺在 NaVPO _{4 F@C 中构建丰富的氧空位。}以解决与电子导电性差相关的问题。密度泛函理论计算和实验研究表明，合适的Cr掺杂和丰富的氧空位可以显着促进电子电导率和Na离子扩散动力学。受益于协同效应，优化后的 Cr 掺杂 NaVPO ₄ F@C 在 1 C 时表现出 121.3 mA hg ^-1的高容量，在 10 C 时表现出 98.8 mA hg ^-1的高倍率容量，容量保持率为 79.3% 4000 次循环后。此外，当组装成全电池（NaTi ₂ (PO ₄ ) ₃@G 薄膜作为阳极）。我们工作中提出的这种简便方法可能提供一种可行的方法来将氧空位设计到其他正极材料中，从而大大提高钠离子电池的性能。