Aqueous sodium-ion batteries have promising prospects in large-scale electrical energy storage, which lack of suitable cathode with high specific capacity and long cycle lifespan, unfortunately. Manganese-based Prussian blue analogs (PBAs) (KMnHCF/NaMnHCF) are ideal candidates for low-cost and high theoretical specific capacity merits. But the rapid decline hinders their application, due to side reactions caused by water imbalance. Here, an equilibrium strategy, which can balance the interstitial water supplement and water attack, is proposed. As proof of the concept, xCS (x: proportion, CS: co-solvent, such as polyethylene glycol and trimethyl phosphate) equilibrium electrolytes are introduced to solve the rapid decline. Assisting with the electrolyte, KMnHCF realizes excellent performance (10 000 cycles), which is beyond most cathode materials of sodium-ion batteries. The full batteries composed of KMnHCF cathode and NaTi₂(PO₄)₃ anode also display outstanding performance (7000 cycles) and promising application prospects at low-temperature and engineering scenes. And then, the equilibrium electrolyte concept is verified by NaMn_0.8Fe_0.2HCF and NaMnHCF, proving its universality for low-cost and long-life manganese based PBAs.

中文翻译：

---

水系钠离子电池平衡电解质实现普鲁士蓝类似物的超长循环

水系钠离子电池在大规模电能存储方面具有广阔的前景，但遗憾的是缺乏合适的高比容量和长循环寿命的正极。锰基普鲁士蓝类似物 (PBA) (KMnHCF/NaMnHCF) 是具有低成本和高理论比容量优点的理想候选者。但由于水失衡引起的副反应，其迅速下降阻碍了它们的应用。在这里，提出了一种平衡策略，可以平衡间隙水的补充和水的攻击。作为概念证明，引入x CS（x：比例，CS：共溶剂，如聚乙二醇和磷酸三甲酯）平衡电解质来解决快速下降的问题。在电解液的辅助下，KMnHCF实现了优异的性能（10 000次循环），超越了大多数钠离子电池正极材料。_{由KMnHCF正极和NaTi 2} (PO ₄ ) ₃负极组成的全电池在低温和工程场景下也表现出优异的性能（7000次循环）和良好的应用前景。然后，通过NaMn _0.8 Fe _0.2 HCF和NaMnHCF验证了平衡电解质概念，证明了其对于低成本、长寿命的锰基PBA的普适性。