Rare-earth Co-doping Promotes High-capacity and Long-cycle Ni-rich Layered Oxide Cathodes via Lattice Stabilization and Interface Engineering

Abstract

Ni-rich layered oxide cathodes are promising candidates for next-generation high-energy-density lithium-ion batteries owing to their high capacity and cost-effectiveness. However, their widespread application is hindered by structural instability, interfacial side reactions, lattice distortion, and microcrack formation during cycling. Herein, a previously unreported synergistic dual rare-earth (Yb/Y) co-doping strategy is proposed for a LiNi0.9Co0.05Al0.05O2 (NCA) cathode to simultaneously stabilize the bulk crystal structure and the electrode–electrolyte interface. Combined experimental results and density functional theory (DFT) analyses demonstrate that Yb/Y incorporation into transition-metal sites effectively enlarges Li+ diffusion pathways, suppresses Li+/Ni2+ cation disorder, and stabilizes lattice oxygen through strong Yb/Y–O bonds, thereby mitigating bulk structural degradation. In addition, a uniform, dense, and mechanically robust cathode-electrolyte interphase (CEI) is formed in situ, effectively mitigating electrolyte corrosion, lowering interfacial resistance, and suppressing particle cracking for NCAYbY. Consequently, the modified NCAYbY cathode exhibits outstanding electrochemical performance, delivering a high reversible capacity of 222.8 mAh g-1 at 0.2 C with 95.79% capacity retention after 100 cycles. Remarkably, the corresponding full cell retains 78.35% capacity after 700 cycles at 1C, while a pouch cell exhibits an initial discharge capacity of ~900 mAh with 78.60% retention after 300 cycles. This work establishes dual rare-earth co-doping as an effective and practical design principle for realizing structurally and interfacially robust Ni-rich cathodes for high-performance, long-life lithium-ion batteries.