Structural water and disordered structure promote aqueous sodium-ion energy storage in sodium-birnessite
Structural water and disordered structure promote aqueous sodium-ion energy storage in sodium-birnessite
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DOI：
10.1038/s41467-019-12939-3
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发表时间：
2019-10
影响因子：
16.6
通讯作者：
Xiaoqian Shan;Fenghua Guo;Daniel S. Charles;Zachary W. Lebens-Higgins;Sara Abdel Razek;Jinpeng Wu;Wenqian Xu;Wanli Yang;K. Page;J. Neuefeind;M. Feygenson;L. Piper;Xiaowei Teng
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文献类型：
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作者：
Xiaoqian Shan;Fenghua Guo;Daniel S. Charles;Zachary W. Lebens-Higgins;Sara Abdel Razek;Jinpeng Wu;Wenqian Xu;Wanli Yang;K. Page;J. Neuefeind;M. Feygenson;L. Piper;Xiaowei Teng
水钠锰矿是一种低成本、环境友好的层状水溶液电化学储能材料，但由于其在水溶液电解质中的电位窗口窄、氧化还原活性低，储能能力差。在本文中，我们报道了一种用于水钠离子电化学存储的富钠无序水钠锰矿（Na0.27MnO2），其容量和循环寿命大大提高（在全电池中5000次循环后为83 mAh g− 1）。中子全散射和原位X射线衍射测量表明，结构水和富Na无序结构都有助于改善当前阴极材料的电化学性能。特别地，在高电位充电过程期间水合水和钠离子的共脱嵌导致层间距离的收缩，从而稳定层状结构。我们的研究结果为结构无序和结构水如何改善层状电极中的钠离子存储提供了真正的见解，并为改进水性电池开辟了一个令人兴奋的方向。
Birnessite is a low-cost and environmentally friendly layered material for aqueous electrochemical energy storage; however, its storage capacity is poor due to its narrow potential window in aqueous electrolyte and low redox activity. Herein we report a sodium rich disordered birnessite (Na0.27MnO2) for aqueous sodium-ion electrochemical storage with a much-enhanced capacity and cycling life (83 mAh g−1after 5000 cycles in full-cell). Neutron total scattering and in situ X-ray diffraction measurements show that both structural water and the Na-rich disordered structure contribute to the improved electrochemical performance of current cathode material. Particularly, the co-deintercalation of the hydrated water and sodium-ion during the high potential charging process results in the shrinkage of interlayer distance and thus stabilizes the layered structure. Our results provide a genuine insight into how structural disordering and structural water improve sodium-ion storage in a layered electrode and open up an exciting direction for improving aqueous batteries.