Rechargeable aqueous Zn/α-MnO₂ batteries are a possible alternative to lithium ion batteries for scalable stationary energy storage applications due to their low cost, safety and environmentally benign components. A critical need for advancement of this battery system is a full understanding of the electrochemical reaction mechanisms, which remain unclear. In this report, operando, spatiotemporal resolved synchrotron X-ray fluorescence mapping measurements on a custom aqueous Zn/α-MnO₂ cell provided direct evidence of a Mn dissolution-deposition faradaic mechanism that governs the electrochemistry. Simultaneous visualization and quantification of the Mn distribution in the electrolyte revealed the formation of aqueous Mn species during discharge and depletion on charge. The findings are supported by ex situ transmission electron microscopy (TEM), X-ray diffraction, Mn K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements. The elucidated mechanism is fundamentally different from the previously proposed Zn²⁺ insertion or conversion reactions. These findings provide a foundation for developing dissolution- deposition chemistries suitable for scalable stationary energy storage with aqueous electrolyte.

中文翻译：

---

Zn /α-MnO2水溶液中锰溶解-沉积机理的时空定量X射线荧光微探针表征

可再充电的水溶液的Zn /α-MnO的₂电池是一种可能的替代，以用于可伸缩固定储能应用的锂离子电池，由于其成本低，安全性和对环境无害的组分。对该电池系统进行改进的关键需求是对电化学反应机理的全面理解，目前尚不清楚。在本报告中，operando，在自定义解决时空同步辐射X射线荧光测量的映射水溶液的Zn /α-MnO的₂该电池提供了控制电化学的锰溶解-沉积法拉第机理的直接证据。电解质中Mn分布的同时可视化和定量分析表明，在放电和电荷耗尽期间会形成Mn水溶液。这些发现得到异位透射电子显微镜（TEM），X射线衍射，Mn K边缘X射线吸收近边缘结构（XANES）和扩展X射线吸收精细结构（EXAFS）的支持。阐明的机理从根本上不同于先前提出的Zn ²⁺插入或转化反应。这些发现为开发适用于水电解质可扩展的固定能量存储的溶解沉积化学方法提供了基础。