Rechargeable Zn/MnO2 batteries using mild aqueous electrolytes are attracting extensive attention due to their low cost, high safety, and environmental friendliness. However, the charge-storage mechanism involved remains a topic of controversy so far. Also, the practical energy density and cycling stability are still major issues for their applications. Herein, a free-standing α-MnO2 cathode for aqueous zinc-ion batteries (ZIBs) is directly constructed with ultralong nanowires, leading to a rather high energy density of 384 mWh g-1 for the entire electrode. Greatly, the H+ /Zn2+ coinsertion mechanism of α-MnO2 cathode for aqueous ZIBs is confirmed by a combined analysis of in situ X-ray diffractometry, ex situ transmission electron microscopy, and electrochemical methods. More interestingly, the Zn2+ -insertion is found to be less reversible than H+ -insertion in view of the dramatic capacity fading occurring in the Zn2+ -insertion step, which is further evidenced by the discovery of an irreversible ZnMn2 O4 layer at the surface of α-MnO2 . Hence, the H+ -insertion process actually plays a crucial role in maintaining the cycling performance of the aqueous Zn/α-MnO2 battery. This work is believed to provide an insight into the charge-storage mechanism of α-MnO2 in aqueous systems and paves the way for designing aqueous ZIBs with high energy density and long-term cycling ability.

中文翻译：

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H +-插入增强型Zn-离子电池用α-MnO2。

使用温和水性电解质的可充电Zn / MnO2电池因其低成本，高安全性和环境友好性而受到广泛关注。但是，到目前为止，所涉及的电荷存储机制仍然是一个有争议的话题。而且，实际的能量密度和循环稳定性仍然是其应用中的主要问题。在此，直接用超长纳米线构建用于水性锌离子电池（ZIBs）的独立式α-MnO2阴极，导致整个电极的能量密度高达384 mWh g-1。伟大的是，通过对原位X射线衍射，非原位透射电子显微镜和电化学方法的综合分析证实了α-MnO2阴极用于水性ZIBs的H + / Zn2 +共聚机理。更有趣的是 考虑到Zn2 +插入步骤中发生的显着容量衰减，发现Zn2 +插入的可逆性比H +插入的可逆性差，这在α-MnO2表面发现了不可逆的ZnMn2 O4层进一步证明了这一点。因此，H +插入过程实际上在维持水性Zn /α-MnO2电池的循环性能中起着至关重要的作用。相信这项工作可提供对水系统中α-MnO2电荷存储机理的深入了解，并为设计具有高能量密度和长期循环能力的ZIB水溶液铺平了道路。H +插入过程实际上在维持Zn /α-MnO2水溶液电池的循环性能中起着至关重要的作用。相信这项工作可提供对水系统中α-MnO2电荷存储机理的深入了解，并为设计具有高能量密度和长期循环能力的ZIB水溶液铺平了道路。H +插入过程实际上在维持Zn /α-MnO2水溶液电池的循环性能中起着至关重要的作用。相信这项工作可提供对水系统中α-MnO2电荷存储机理的深入了解，并为设计具有高能量密度和长期循环能力的ZIB水溶液铺平了道路。