Constructing Stable Sub/Surface Structure to Boost Superior Cyclabilities of Single‐Crystalline Ni‐Rich Cathode

Abstract Under prolonged high‐voltage cycling, single‐crystalline Ni‐rich cathodes are prone to severe transition metal dissolution, irreversible phase transformations, and reduced structural stability, which significantly hinder their practical application. Hence, a dual‐modification strategy is proposed and implemented for single‐crystalline LiNi 0.90 Co 0.05 Mn 0.05 O 2 (SCNCM90) cathodes by introducing Al/B gradient co‐doping and an Al 5 BO 9 surface coating to mitigate anisotropic structural changes. The subsurface Al/B gradient doping induces a lithium‐rich vacancy disordered structure, which effectively suppresses the H2‐H3 phase transition, while suppressing lattice strain and mechanical degradation. In parallel, the chemically stable Al 5 BO 9 surface coating significantly mitigates harmful electrode‐electrolyte interfacial reactions, thereby enhancing both structural and electrochemical stability under high‐voltage conditions. Electrochemical tests reveal that the Al/B co‐modified SCNCM90 electrode exhibits markedly improved performance, achieving 95.83% capacity retention after 200 cycles at 4.5 V and maintaining 89.6% retention at 1C after 1000 cycles in pouch‐type full cells within 3–4.25 V. Moreover, the modified electrode demonstrates superior lithium‐ion diffusion kinetics and enhanced thermodynamic stability during cycling. This effective dual‐modification strategy offers a promising pathway to improve the structural robustness and electrochemical durability of single‐crystalline Ni‐rich cathodes, thus accelerating their adoption in next‐generation high‐energy lithium‐ion batteries.