The discovery of suitable electrode materials is extremely important for the success of Na-ion batteries (NIBs). In this work, a phosphate-typed polyanionic compound Na₃(VO)(PO₄)(HPO₄) is explored as a new cathode material of NIBs for the first time. The as-synthesized Na₃(VO)(PO₄)(HPO₄) sample presents as well-crystallized nanoparticles. Without any carbon coating and high-temperature treatment, it exhibits about one mole Na⁺ (de)intercalation with an average voltage of ∼ 3.5 V, outstanding cycling stability with 71% capacity retention after 500 cycles at 1C and superior reaction kinetics with a large Na⁺ diffusion coefficient of around 10^-10 cm² s^-1 (comparable with other carbon-coated Na superionic conductors). The excellent Na-storage performance suggests that the Na₃(VO)(PO₄)(HPO₄) compound may be a potential cathode for NIBs. Further analyses demonstrate the as-prepared electrode experiences a series of highly reversible phase-transition and solid-solution reactions during Na⁺ extraction/insertion with a V⁴⁺/V⁵⁺ redox couple.

发现合适的电极材料对于钠离子电池（NIB）的成功极为重要。在这项工作中，首次探索了磷酸盐型聚阴离子化合物Na ₃（VO）（PO ₄）（HPO ₄）作为NIBs的新型阴极材料。合成后的Na ₃（VO）（PO ₄）（HPO ₄）样品呈现出良好结晶的纳米颗粒。在没有任何碳涂层和高温处理的情况下，它表现出约一摩尔的Na ⁺（去）插层，平均电压为〜3.5 V，出色的循环稳定性，在1C 500次循环后具有71％的容量保持率，并具有出色的反应动力学和较大的钠⁺扩散系数约为10 ^-10 cm ² s ^-1（与其他碳包覆的Na超离子导体相比）。优异的钠存储性能表明，Na ₃（VO）（PO ₄）（HPO ₄）化合物可能是NIB的潜在阴极。进一步的分析表明，所制备的电极在用V ⁴⁺ / V ⁵⁺氧化还原对进行Na ⁺萃取/插入过程中经历了一系列高度可逆的相变和固溶反应。