The working mechanism of LiCoO₂ beyond 4.6 V presents complicated issues: (1) the ambiguous multistructural evolutions, (2) the vague O-related anionic redox reactions (ARR) triggered by the overlap Co–O bands, and (3) the serious electrode–electrolyte interface stability challenges. The intricate relationship among them turns into a classic “chicken and egg” conundrum, leading to a confusing evolution process of LiCoO₂. Herein, from an ingenious perspective combining stacking faults and nonhomogeneous delithiation, we originally demonstrate a series of intergrowth phase evolutions from O3 to O1, passing through the so-called H1-3 phase. Moreover, in sharp contrast to the O–O dimer formed in a traditional Li-rich layered cathode, a moderate and stable arrangement of oxidized lattice oxygen is unveiled as a manifestation of ARR in LiCoO₂. Additionally, we clarify the nature that dehydrogenation and hydrolysis of electrolyte trigger the chain decompositions and intensify the surface degradation.

中文翻译：

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揭秘 LiCoO2 超越 4.6 V 的演变

_{LiCoO 2}超过4.6 V的工作机制提出了复杂的问题：（1）模糊的多结构演化，（2）由重叠的Co-O带引发的模糊的O相关阴离子氧化还原反应（ARR），以及（3）严重的电极-电解质界面稳定性挑战。它们之间错综复杂的关系变成了一个经典的“先有鸡还是先有蛋”的难题，导致了LiCoO ₂令人困惑的演化过程。在此，我们从结合堆垛层错和非均匀脱锂的巧妙角度，首次展示了从O3到O1的一系列共生相演化，经过所谓的H1-3相。此外，与传统富锂层状正极中形成的O-O二聚体形成鲜明对比，氧化晶格氧的适度且稳定的排列被揭示为LiCoO 2 中ARR的_表现。此外，我们阐明了电解质脱氢和水解引发链分解并加剧表面降解的本质。