Liu Jiahe, Yang Cheng, Wen Bo, Li Ben, Liu Yu
Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Small. 2023 Nov;19(46):e2303896. doi: 10.1002/smll.202303896. Epub 2023 Jul 17.
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 NaTi (PO ) 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 Fe HCF and NaMnHCF, proving its universality for low-cost and long-life manganese based PBAs.
水系钠离子电池在大规模电能存储方面具有广阔前景，但遗憾的是，目前缺乏具有高比容量和长循环寿命的合适正极材料。锰基普鲁士蓝类似物（PBAs）（KMnHCF/NaMnHCF）因其低成本和高理论比容量的优点，是理想的候选材料。但由于水失衡引起的副反应，其容量快速衰减阻碍了它们的应用。在此，我们提出了一种平衡策略，该策略可以平衡间隙水的补充和水的侵蚀。作为概念验证，引入了xCS（x：比例，CS：共溶剂，如聚乙二醇和磷酸三甲酯）平衡电解质来解决容量快速衰减的问题。在该电解质的辅助下，KMnHCF实现了优异的性能（10000次循环），这超过了大多数钠离子电池正极材料。由KMnHCF正极和NaTi(PO₄)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）和广阔的应用前景。然后，通过NaMn₂Fe(CN)₆和NaMnHCF验证了平衡电解质的概念，证明了其对于低成本、长寿命的锰基PBAs的通用性。
