在丰富的金属氧化物中的四面体的可视化
Weixin Song1,2,3, Miguel A Pérez-Osorio1,2,3, Jun Chen1,2,3
1Department of Materials, University of Oxford, Oxford OX1 3PH, U.K.
Journal of the American Chemical Society
|August 14, 2024
概括
在丰富的层氧化物中研究离子扩散揭示了循环过程中的关键路径和结构变化. 了解这些路径对于提高电池性能和动力学至关重要.
科学领域:
- 材料科学
- 电化学
- 固态化学
背景情况:
- 富含的层状过渡金属 (TM) 氧化物是高能量密度电池的有希望的阴极材料.
- 缓慢的动力学,特别是与阳离子氧 (O2-) 氧化还原有关,阻碍了它们的实际应用.
- 了解+离子扩散途径,特别是与TM和O2-氧化还原相联系,对于优化性能至关重要.
研究的目的:
- 在充电-放电循环期间阐明+离子迁移途径.
- 将+离子扩散与结构重组相关联,包括TM迁移和相位过渡.
- 确定减轻+扩散干扰的策略,以提高电池性能.
主要方法:
- 同时使用电子图谱和环状暗场成像来可视化Li+离子动态.
- 密度函数理论 (DFT) 的计算用于支持Li+配置的实验观测.
- 在电化学循环过程中的现场/操作分析提供了关于动态结构变化的见解.
主要成果:
- +离子通过层中的八面体-四面体-八面体路径迁移.
- 在氧化过程中,Li+离子在层中占据四面体位置,形成Li-Li子配置.
- 观察到TM迁移和O3到O1相过渡,破坏四面体Li+的稳定性并影响扩散.
结论:
- 这项研究揭示了由结构变化影响的富含的层状氧化物中复杂的Li+扩散景观.
- 循环后永久的TM迁移到位阻碍了Li+四面体位的占用和扩散.
- 尽量减少结构中断是优化Li+扩散和电池性能的关键.
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