Integrated hierarchical lanthanum niobium oxide surface coating to stabilize high-voltage performance and suppress Ni2+/Li+ cationic disorder in nickel-rich layered cathodes

High-nickel ternary materials are the most promising lithium battery cathodes in terms of application and development potential. These materials face significant problems at elevated voltage, including cation mixing, interfacial reactions, microcracks, and lattice oxygen loss, which undermine their cyclic stability and safety. Metal oxide coating is the most direct and effective solution to alleviate this material degradation. Herein, we present an integrated LaNbO4 (LN) surface coating strategy for improving LiNi0.88Mn0.02Co0.10O2's (NMC-88) electrochemical performance and structural stability. The coating materials penetrate the bulk-layered structure and enhance structural integrity. Additionally, it protects the cathode surface against undesirable parasitic side reactions and achieves excellent electrochemical properties, optimal rate performance, and cyclic stability by improving lithium diffusion. The modified cathode maintains a specific capacity of 42 %, while the pristine NMC88 cathode holds 25.69 % after 150 cycles at 2.8-4.5 V under 2C. The surface modification method reduces the H2-H3 phase and the overgrowth of the solid electrolyte interface, leading to enhanced cyclic performance. In comparison to NMC-88, the improved electrochemical performance and structural integrity of LN-coated NMC88 are linked to the decrease in microcrack defects during cycling.