Aqueous sodium-ion batteries (AIBs) are promising candidates for large-scale energy storage due to their safe operational properties and low cost. However, AIBs have low specific energy (i.e., <80 Wh kg⁻¹) and limited lifespans (e.g., hundreds of cycles). Mn-Fe Prussian blue analogues are considered ideal positive electrode materials for AIBs, but they show rapid capacity decay due to Jahn-Teller distortions. To circumvent these issues, here, we propose a cation-trapping method that involves the introduction of sodium ferrocyanide (Na₄Fe(CN)₆) as a supporting salt in a highly concentrated NaClO₄-based aqueous electrolyte solution to fill the surface Mn vacancies formed in Fe-substituted Prussian blue Na_1.58Fe_0.07Mn_0.97Fe(CN)₆ · 2.65H₂O (NaFeMnF) positive electrode materials during cycling. When the engineered aqueous electrolyte solution and the NaFeMnF-based positive electrode are tested in combination with a 3, 4, 9, 10-perylenetetracarboxylic diimide-based negative electrode in a coin cell configuration, a specific energy of 94 Wh kg^–1 at 0.5 A g⁻¹ (specific energy based on the active material mass of both electrodes) and a specific discharge capacity retention of 73.4% after 15000 cycles at 2 A g⁻¹ are achieved.

水系钠离子电池 (AIB) 因其安全的运行特性和低成本而成为大规模储能的有前途的候选者。然而，AIB 的比能较低（即 <80 Wh kg ^-1）且寿命有限（例如数百个循环）。Mn-Fe 普鲁士蓝类似物被认为是 AIB 的理想正极材料，但由于 Jahn-Teller 畸变，它们显示出快速的容量衰减。为了避免这些问题，在这里，我们提出了一种阳离子捕获方法，该方法涉及在高浓度 NaClO ₄基水溶液中引入亚铁氰化钠 (Na ₄ Fe(CN) ₆ ) 作为支持盐以填充表面 Mn在 Fe 取代的普鲁士蓝中形成的空位 Na _1.58循环过程中的Fe _0.07 Mn _0.97 Fe(CN) ₆  · 2.65H ₂ O (NaFeMnF)正极材料。当工程电解质溶液和基于 NaFeMnF 的正电极与基于 3、4、9、10-苝四羧酸二酰亚胺的负电极组合在纽扣电池配置中进行测试时，比能量为 94 Wh kg –1^在0.5在 2 A g ^-1下实现了15000 次循环后的g ^-1（比能量基于两个电极的活性材料质量）和 73.4% 的比放电容量保持率。