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在Wadsley-Roth结构中极端缺陷耐受性由转变稳定NaNb₇O₁₈

Sarah L Ko¹, Jordan A Dorrell², Ethan D Alter¹

¹Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States.

Journal of the American Chemical Society

|February 3, 2025

概括

这项研究引入了NaNb7O18,一种具有异常耐缺陷的新型电池材料,尽管结构不完善,但能够实现快速的离子传输和高容量循环. 它展示了一种新的电荷储存机制,涉及可逆的-键形成.

科学领域:

材料科学
固态化学
电化学

背景情况:

缺陷化学极大地影响了晶体化合物的运输现象,特别是1D离子导体.
瓦兹利-罗斯块相因其高氧化还原能力和离子扩散性而闻名,其道结构具有潜在的缺陷耐受性.

研究的目的:

描述一种新的离子电池负极材料,NaNb7O18,具有极高的缺陷耐受性.
阐明NaNb7O18及其化相的结构和电化学特性.

主要方法:

包括中子衍射,23Na固态NMR光谱和DFT计算在内的多模性表征.
运行同步 difraktion 来研究化/脱化过程.
电化学循环性能评估

主要成果:

NaNb7O18具有极高的缺陷耐受性,其中超过一半的Na+离子处于扩散阻塞位.
可逆化为Li7NaNb7O18具有高循环容量 (200 mAh·g-1在10小时内,100 mAh·g-1在3分钟内).
具有两种第一阶段过渡的异构化/脱化和可逆Nb-Nb键形成的证据.

结论:

NaNb7O18是一种高度耐缺陷的1D离子导体,适用于高速电池应用.
在瓦兹利-罗斯化合物中,可逆的Nb-Nb键形成被证实为电荷储存机制.
这种材料的独特结构使其能够快速输送离子,尽管存在很大的缺陷度.

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