Manganese hexacyanomanganates have attracted significant attention as promising cathode materials for sodium-ion batteries owing to the high theoretical capacity and low cost of Mn resources. Because of the strong Jahn–Teller effect, causing unstable local phase transition and distortion, the redox reactions of the high-spin state of Mn(III) are considered to be a conundrum. Herein, it is reported that the charge-redistribution mechanism of low-spin Mn^III + high-spin Mn^III → low-spin Mn^II + high-spin Mn^IV in manganese hexacyanomanganates can decrease unstable high-spin Mn^III, leading to the mitigation of Jahn–Teller distortion. X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy suggest that the fast reaction rate activates charge redistribution. Moreover, different crystal structures, reported using post-mortem synchrotron X-ray diffraction analysis, confirm a large orthorhombic structure, thus verifying the presence of charge redistribution based on the superexchange rule. These results demonstrate that manganese hexacyanomanganate in an aqueous electrolyte can achieve long-term cyclability, thus paving the way for high-performance batteries.

中文翻译：

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通过快速电极动力学诱导电荷再分配来减轻 Jahn-Teller 效应

由于锰资源的高理论容量和低成本，六氰基锰酸锰作为钠离子电池的有前途的正极材料引起了人们的广泛关注。由于强 Jahn-Teller 效应，导致不稳定的局部相变和畸变，Mn(III) 的高自旋态的氧化还原反应被认为是一个难题。在此，据报道，六氰锰酸锰中低自旋 Mn ^III  + 高自旋 Mn ^III  → 低自旋 Mn ^II  + 高自旋 Mn ^IV的电荷再分配机制可以降低不稳定的高自旋 Mn ^III，从而减轻了 Jahn-Teller 失真。X 射线吸收近边光谱和 X 射线光电子能谱表明快速反应速率激活了电荷重新分布。此外，使用死后同步加速器 X 射线衍射分析报告的不同晶体结构证实了大的正交结构，从而验证了基于超交换规则的电荷重新分布的存在。这些结果表明，水性电解质中的六氰基锰酸锰可以实现长期循环性，从而为高性能电池铺平道路。