Up to now, LiCoO 2 (LCO) cathode material still occupies an important position in the consumer electronics market due to its ultra-high tap density and volumetric energy density. [1][2][3][4] It is reported that increasing the charging cutoff potential, usually larger than 4.4 V corresponding to more than removal amount of 0.6 Li + in LiCoO 2 , can effectively improve the energy density of the LCO. [5,6] However, it will also cause a sharp decline in the cycling performance originated from a series of phase transitions for high-voltage LiCoO 2 (H-LCO). [7][8][9] Herein, the release of surface oxygen and the loss of cobalt ions are other main reasons for the capacity attenuation of H-LCO. [10,11] Typically, in the low-voltage region, the LCO will undergo the insulator-to-metal phase transition, and the hexagonal structure H-1 phase will gradually transform into hexagonal structure H-2 phase. When the charging voltage reaches 4.2 V, the LCO material delivers a reversible transformation from O3 phase in the R-3m space group to monoclinic structure, and then back to O3 phase, which involves the "order ⇆ disorder" transformation of crystalline phase. In this process, the change in crystal parameters caused by the spatial mismatch between lithium ion and lithium vacancy will lead to the change in particle volume for LCO. Finally, another phase transformation of LiCoO 2 from O3 phase to H1-3 phase occurs when charging to above 4.5 V. In these reversible phase transitions, the transformation of "O3 phase ⇆ monoclinic structure" will significantly reduce the Li + diffusion kinetics, and during the further transformation of "O3 phase → H1-3 phase," severe mechanical stress and cracks will appear in the bulk material, accompanied by the decrease in Li + diffusion rate, which leads to the last rapid capacity fading. Thus, overcoming these obstacles is significant for the development of H-LCO materials.Generally, many strategies have been developed to overcome the cycling stability fading of H-LCO. On the one hand, foreign element doping in bulk phase has been demonstrated to be promising and effective for the improvement of H-LCO LIB performance, [12,13] which can inhibit the irreversible phase transformation, improve the stability of the phase structure, and alleviate the stress and deformation caused by the structural transformation during the charge/discharge process. For example, Zhao et al. found that Sn 4+ doping can inhibit the conversion of LCO to spinel phase under high potential due to the decrease in the
