Sustainable LiCoO<sub>2</sub> by collective glide of CoO<sub>6</sub> slabs upon charge/discharge.

Li, Shuai; Sun, Yang; Gao, Ang; Zhang, Qinghua; Lu, Xueyi; Lu, Xia · Proc Natl Acad Sci U S A · 2022

basic_science · Level V

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Abstract

SignificanceTraditional views indicate that the well-known layered LiCoO<sub>2</sub> cathode delivers a typical solid-solution reaction upon delithiation. The problem is that "solid solution" is a vague concept, and the phase transition remains ambiguous. Here, we reveal a mechanism with the collective and quasi-continuous glide of CoO<sub>6</sub> slabs in layered LiCoO<sub>2</sub> through combining in situ XRD and ex situ STEM characterizations. Such a delithiation mechanism does not involve the nucleation-and-growth-type delithiation process and represents a completely different manner from the conventional two-phase or solid solution-phase transition processes. The lessons provide a different insight into understanding the working mechanism of layered oxide materials.