LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), a Ni-rich layered oxide, is a promising cathode material for high-energy density lithium-ion batteries (LIBs). However, its structural instability, caused by adverse phase transitions and continuous oxygen release, as well as deteriorated interfacial stability due to excessive electrolyte oxidative decomposition, limits its widespread application. To address these issues, a new concept is proposed that surface targeted precise functionalization (STPF) of the NCM811 cathode using a synergistic slurry additive (SSA) approach. This approach involves coating the NCM811 particle surface with 3-aminopropyl dimethoxy methyl silane (3-ADMS), followed by the precise deposition of ascorbic acid via an acid-base interaction. The slurry additives induce the formation of an ultra-thin spinel surface layer and a stable cathode–electrolyte interface (CEI), which enhances the electrochemical kinetics and inhibits crack propagation. The STPF strategy implemented by the SSA approach significantly improves the cyclic stability and rate performance of the NCM811 cathode in both half-cell and full-cell configurations. This work establishes a promising strategy to enhance the structural stability and electrochemical performance of nickel-rich cathodes and provides a feasible route to promote practical applications of high-energy density lithium-ion battery technology.

Nickel-rich cathode materials have attracted widespread interest due to their high capacity; however, the structure is prone to degradation and collapse during cycling, resulting in poor stability performance and safety, hindering the development of high-nickel cathode materials. Here, we propose a straightforward method to consume oxygen on the surface of primary particles during the high-temperature calcination process of precursors, inducing the coupled rearrangement of surface cations, resulting in the in situ generation of a nano-sized mixed spinel/rock salt defect phase, which is confirmed by high-angle annular dark-field scanning transmission electron microscopy. LiNi_0.8Co_0.1Mn_0.1O₂ modified with mixed phase not only can reduce side reactions with the electrolyte, resulting in fewer by-products such as LiF and Li₂CO₃, preventing the formation of excessively thick cathode–electrolyte interface layers, but also can avoid irreversible phase transitions and prevents lattice mismatches. As a result, the cycling performance has been improved to some extent, benefiting from structural stability. In addition, the special 3-dimensional structure of the spinel phase allows the material surface to expand ion transport channels and enhance multiplicative performance. Therefore, this study provides a new perspective on the modification of high-nickel materials and extends the application of nickel-rich materials.