Anchoring the Oxygen Framework: A Cation-Pinning Strategy for Durable High-Voltage Cycling and Strain Suppression of Ni-Rich Layered Cathodes

Abstract

Abstract Anionic redox reactions (ARRs) in ultrahigh-nickel layered oxides provide additional capacity for high-energy lithium-ion batteries, yet irreversible oxygen charge compensation at high voltage remains a critical challenge. Herein, a tungsten (W)-doping strategy is developed in LiNi0.9Co0.05Mn0.05O2 (NCM90) to regulate defect–oxygen coupling and stabilize reversible oxygen redox chemistry. Neutron diffraction analysis corroborates that the incorporation of W significantly decreases the intrinsic Li/Ni antisite defect concentration, attenuates the oxygen-redox-active Li–O–Li configurations, alleviates irreversible oxygen oxidation, and consequently inhibits the regeneration of Li/Ni antisite defects over extended cycling. Meanwhile, strong W–O interactions increase oxygen vacancy formation energy, inhibit transition-metal migration, and stabilize the lattice oxygen framework. Combined in situ X-ray diffraction, theoretical calculations, and finite element analysis demonstrate that W-induced defect regulation homogenizes Li+ distribution and alleviates lattice strain accumulation during high-voltage cycling. Consequently, W-doped NCM90 achieves over 90% capacity retention after 100 cycles at 4.6 V and 1 C, exhibiting significantly enhanced cycling stability. This work uncovers the intrinsic coupling between Li/Ni antisite defects and oxygen redox evolution and establishes a defect–oxygen coupling regulation strategy that provides a general framework for designing durable cathode materials with reversible anionic redox chemistry.