Beyond Conventional Doping: High-Valence Element Integrated Slight Li Enrichment in Ni-Rich Cathodes with High Capacity and Ultralong Cycle Life

Ni-rich cathodes face challenges such as rapid capacity fade from phase transitions and interfacial degradation. While high-valence doping stabilizes the structure, it often compromises initial capacity and requires further cycling improvement. This study introduces a synergistic comodification of high-valence tungsten doping and controlled lithium enrichment in Li 1+1.5 x (Ni 0.92 Co 0.04 Mn 0.04 ) 1–2.5 x W x O 2 ( x = 0.003, 0.006, 0.01, 0.04) cathodes. This strategy simultaneously tailors crystallographic orientation, forms a protective Li 4+α Ni 1-α WO 6 (α = 0, 0.1) interfacial layer, and quantitatively optimizes cationic disordering. These effects collectively decelerate the detrimental H2–H3 phase transition and suppress interfacial degradation. The optimized Li 1.009 (Ni 0.92 Co 0.04 Mn 0.04 ) 0.985 W 0.006 O 2 cathode delivers a high initial capacity of 226.9 mAh g –1 along with exceptional cycling stability, retaining 99.2% of its capacity after 200 cycles in a half-cell and 96.7% after 1000 cycles at 1 C in a full-cell, markedly surpassing its solely W-doped or Li-enriched counterparts. This work demonstrates that controlled lithium enrichment maximizes the stabilization effect of high-valence dopants, enabling long-life, high-energy-density Li-ion batteries.