Stabilizing Surface Lattice On‐ (0<n<2) for Long‐Term Durability of LiCoO2

The instability of surface lattice On‐ (0<n<2) in the charged LiCoO₂ (LCO) limits its long‐term cycling stability beyond 4.55 V vs. Li/Li⁺. Herein, the spinel and rock‐salt (RS) phases are constructed on the LCO surface to stabilize lattice On‐, namely S‐LCO and R‐LCO, respectively. Upon long‐term cycling at 4.6 V, the loss of lattice On‐ leads to a progressive deterioration of surface spinel phase, which ultimately transfers to a strong Li+‐blocking phase. In contrast, for R‐LCO, the surface lattice On‐ in the RS phase retains stable in long‐term cycles. Theoretical calculations reveal that the migration barriers of lattice On‐ are significantly higher in the RS phase than that in the spinel phase. Due to the stabilized surface lattice On‐, the R‐LCO||Li cell shows a impressive capacity retention of 78.6% in 1000 cycles at 4.6 V (current of 1 C), and superior floating charge durability at 45℃. This study highlights the importance of surface structure tailoring in developing the advanced LCO cathodes.