Sustainable LiCoO 2 by collective glide of CoO 6 slabs upon charge/discharge

SignificanceTraditional views indicate that the well-known layered LiCoO2 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 CoO6 slabs in layered LiCoO2 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.