Strengthening the interfacial stability of single-crystal LiNi_0.88Co_0.09Mn_0.03O₂ cathode with multiple-function surface modification

The instability in the structural integrity caused by interfacial issues is commonly regarded as the primary drawback of Ni-rich layered cathode materials (LiNi_xCo_yMn_1-x-yO₂, where x ≥ 0.8), which must be addressed before their commercial application. Herein, a novel multiple-function surface modification strategy is proposed based on the single crystal structure to in-situ achieve the construction of a coating layer and surface doping with Ce element to enhance the structural stability of the LiNi_0.88Co_0.09Mn_0.03O₂ (NCM). Notably, the introduction of Ce-O bonding adjusts the local oxygen coordination to achieve a more stabilized structure of the oxygen framework, which inhibits the evolution of lattice oxygen and enhances conductivity. Additionally, by benefiting from the in-situ synthesized coating layer of Li_xCeO₂, the occurrence of side reactions on the surface is effectively alleviated, resulting in a reduction in electrode polarization. Combined with comprehensive electrochemical tests, it is confirmed that the improved electrochemical performance originates from the reduction of the detrimental H2-H3 phase transition and enhanced conductivity. As expected, the modified material with 1 wt% content of Ce (NCM@Ce) exhibits a high initial discharge capacity of 196.3 mAh g^-1 with a capacity retention of 79.7 % after 200 cycles, and its energy density reaches 574.3 Wh kg^-1 after 200 cycles.