Buffer reactions can prevent changes induced by external causes. Here, we demonstrate the significant buffer role of a very small amount of Mn in a self-optimized cathode for an aqueous Zn-ion battery. Our operando X-ray characterization studies reveal that the dissolution of most of the Mn in MnV₂O₄ during the first charging cycle induces atomic re-arrangement to form a disordered vanadium oxide phase with 0.88 at% Mn. Interestingly, the residual Mn ions exhibit voluntary migration between tetrahedral and octahedral sites during Zn²⁺ de/intercalation. This Mn migration not only stabilizes the main structure of the vanadium-based electrode, but also modulates the Fermi surface of V 3d against excessive drift. As result, the optimized cathode delivers an excellent capacity of 610.2 mA h g⁻¹ at 0.2 A g⁻¹ and long-term cycling stability over 4000 cycles. This buffer contribution via tunable metal ions exhibits high potential for applications in long-life metal-ion batteries and related fields.

中文翻译：

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锰缓冲液诱导锌电池中高性能无序MnVO阴极

缓冲液反应可以防止由外部原因引起的变化。在这里，我们证明了在水性Zn离子电池的自优化阴极中，非常少量的Mn具有显着的缓冲作用。我们的操作X射线表征研究表明，在第一个充电周期中，大多数Mn在MnV ₂ O ₄中的溶解会引起原子重排，形成具有0.88 at％Mn的无序氧化钒相。有趣的是，在Zn ²⁺期间，残留的Mn离子在四面体和八面体位点之间表现出自发迁移de / intercaling。Mn的迁移不仅稳定了钒基电极的主要结构，而且还调节了V 3d的费米表面以防止过度漂移。结果，优化的阴极在0.2 A g ^-1时具有610.2 mA hg ^-1的出色容量，并在4000次循环中具有长期循环稳定性。通过可调金属离子产生的这种缓冲作用在长寿命金属离子电池及相关领域中具有很高的应用潜力。