With the growing demand for high-capacity rechargeable batteries, continuous advancements in cathode materials are imperative. Among the candidate materials, Li-excess Mn-rich (LMR) cathodes, known for their superior capacity compared to traditional cathodes, are gaining attention for commercialization. However, Li₂MnO₃, predominantly used in LMR cathodes, undergoes structural degradation in the voltage plateau region, and its atomic-level mechanisms have not yet been precisely elucidated. Herein, we use first-principles density functional theory calculations to investigate the process of structural change and redox mechanisms of Li₂MnO₃ induced by local strain. Our studies suggest that local intrinsic strain significantly influences changes in redox mechanisms, Mn migration, and the formation of O–O dimers. Furthermore, the process of structural collapse due to strain was further confirmed through ab initio molecular dynamics calculations. As a final step, we observed the collapse process until all of the Li ions were completely removed from the structure. Our results, considering the effects of local strain, integrate existing degradation mechanisms of Li₂MnO₃ and provide advanced understanding and new insights for its improvement.

中文翻译：

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揭示 Li 过量锰阴极中局部应变诱导的结构降解机制


随着对大容量可充电电池的需求不断增长，正极材料的不断进步势在必行。在候选材料中，与传统阴极相比，富锂锰 （LMR） 阴极以其优越的容量而闻名，其商业化越来越受到关注。然而，主要用于 LMR 阴极的 Li₂MnO₃ 在电压平台区发生结构退化，其原子级机制尚未被精确阐明。在本文中，我们使用第一性原理密度泛函理论计算来研究局部应变诱导的 Li₂MnO₃ 的结构变化过程和氧化还原机制。我们的研究表明，局部内在应变显着影响氧化还原机制的变化、Mn 迁移和 O-O 二聚体的形成。此外，通过从头开始的分子动力学计算进一步证实了由于应变引起的结构崩溃过程。最后一步，我们观察了塌陷过程，直到所有锂离子都从结构中完全去除。我们的结果考虑了局部应变的影响，整合了 Li₂MnO₃ 的现有降解机制，为其改进提供了更深入的理解和新的见解。