Stabilizing Surface Lattice O<i><sup>n</sup></i><sup>−</sup> (0 < <i>n</i> < 2) for Long‐Term Durability of LiCoO<sub>2</sub>
Wenguang Zhao, Mingyang Li, Zijian Li, Hengyu Ren, Xiaohu Wang, Xingxing Yin, Wangyang Ding, Guojie Chen, Shiming Chen, Haocong Yi, Shunning Li, Jun Wang, Dong Zhou, Lin Zhou, Hai Lin, Bin Fei, Feng Pan, Qinghe Zhao
Abstract
Abstract The instability of surface lattice O n − (0 < n < 2) in charged LiCoO₂ (LCO) limits its long‐term cycling stability beyond 4.55 V versus Li/Li⁺. Herein, the spinel and rock‐salt (RS) phases are constructed on LCO surface to stabilize lattice O n − , namely S‐LCO and R‐LCO, respectively. Upon long‐term cycling at 4.6 V, the loss of lattice O n − leads to a progressive deterioration of surface spinel phase, which ultimately transforms into a strong Li + ‐blocking phase. In contrast, for R‐LCO, the surface lattice O n − in the RS phase remains stable in long‐term cycles. Theoretical calculations reveal that the migration barriers of lattice O n − are significantly higher in the RS phase than in the spinel phase. Due to the stabilized surface lattice O n − , the R‐LCO||Li cell shows an impressive capacity retention of 78.6% after 1000 cycles at 4.6 V (at 1C rate) and superior floating charge durability at 45 °C. This study highlights the importance of surface structure tailoring in developing advanced LCO cathodes.