Enhancing Structural Stability and Kinetics of Ni-Rich Cathodes via Synergistic Bulk and Interface Optimization.

Ni-rich layered oxide cathodes LiNixCoyMn1-x-yO₂ (NCM, x ≥ 0.8) suffer from concurrent structural instability, interfacial degradation caused by residual lithium, and sluggish Li⁺ diffusion kinetics, which severely limit their application in high-energy lithium-ion batteries. Although extensive efforts have been devoted to addressing these issues, strategies capable of concurrently regulating the bulk structure, surface chemistry, and Li⁺ diffusion kinetics in a simple and scalable manner remain limited. Herein, a simple Ti and Nb comodification strategy via secondary calcination is proposed to synergistically regulate bulk structure, surface chemistry, and Li⁺ transport in Ni-rich cathodes. The incorporation of high valence Ti and Nb induces controlled Li/Ni antisite defects, which enhance the lattice and thermal stability of the cathodes. Meanwhile, the comodification reduces surface residual lithium, suppresses interfacial side reactions, and introduces oxygen vacancies, thereby enhancing Li⁺ diffusion kinetics. Benefiting from this synergistic regulation, the modified cathode delivers a high rate capacity of 174 mAh g⁻¹ at 5 C and retains 94% capacity after 100 cycles at 1 C. This work provides an effective strategy for constructing Ni-rich cathodes with high structural stability and excellent performance for next-generation high-energy LIBs.