Prussian blue (PB) and its analogs (PBAs) have attracted significant attention as cathode materials for sodium-ion batteries due to their facile synthetic procedure, low cost as well as high capacity. Although a large amount of effort has been made on material innovations, the alkali-site alternative design strategy for PBAs is still elusive. A new strategy of adding multivalent cations in the electrolyte is proposed to improve the structural stability of PBA and promote sodium ions diffusion rate. In particular, Ba²⁺ can insert in the PBA lattice via in-situ electrochemical reaction when the battery is performed in charging-discharging process. Therefore, Ba²⁺ acts as a “defender” to maintain the frame stability and prevent residual water from entering the lattice. By reasonably controlling the additive amount of Ba²⁺ in the electrolyte, the as-prepared cathode shows remarkably enhanced structural stability with a capacity retention of 96.6% after 150 cycles and delivers a capacity of 83.41 mAh g⁻¹ even at 6 C. This work provides important insights into the development of alkaline-site substitution strategies for high-performance cathode materials in sodium-ion batteries.

普鲁士蓝 (PB) 及其类似物 (PBAs) 作为钠离子电池的正极材料，由于其合成过程简单、成本低和容量大而备受关注。尽管在材料创新方面做出了大量努力，但 PBA 的碱基替代设计策略仍然难以捉摸。提出了一种在电解质中添加多价阳离子的新策略，以提高 PBA 的结构稳定性并促进钠离子扩散速率。特别地，当电池在充放电过程中进行时， Ba ^{2+可以通过}原位电化学反应插入PBA晶格中。因此，Ba ²⁺充当“后卫”以保持框架的稳定性并防止残留的水进入格子。通过合理控制电解液中Ba ²⁺的添加量，所制备的正极显示出显着增强的结构稳定性，在150次循环后容量保持率为96.6%，即使在6 C下也能提供83.41 mAh g ^-1的容量。这这项工作为钠离子电池中高性能阴极材料的碱位取代策略的发展提供了重要的见解。