Restraining Mechanochemical Failure in High‐Voltage Ni‐Rich Cathode by Coupling Bulk Lattice Pinning With Interphase Self‐Reconstruction

ABSTRACT Ultrahigh‐nickel layered oxides deliver exceptional energy and power densities for lithium‐ion batteries (LIBs). However, they suffer from severe intra‐ and intergranular cracking driven by accumulated intragranular strain and intergranular parasitic reactions. Herein, a synergistic strategy coupling bulk lattice pinning with interphase self‐reconstruction is proposed to simultaneously suppress these cross‐scale mechanochemical degradation. A coherently grown LiTaO 3 phase stabilizer is introduced into the layered lattice, markedly reducing anisotropic strain by suppressing unit‐cell volume and c‐axis fluctuations through a pinning effect. This stabilized framework further promotes finer and elongated primary particles with eliminated intergranular voids, thereby restraining intragranular cracking and preserving bulk structural integrity. Concurrently, a self‐reconstructing interphase is in situ generated via H + ‐donor decomposition during cycling, forming robust LiF and Li 3 PO 4 inorganic maskants that shield parasitic reactions and inhibit intergranular cracking under high voltage. This dual bulk‐interphase synergistic stabilization enables the cathode superior mechanochemical stability and reaction homogeneity under harsh conditions (4.8 V, 60°C, and 5 C). Consequently, the cathode achieves 94.3% capacity retention after 200 cycles at 4.6 V, while practical pouch cells maintain 83.1% capacity over 600 cycles. By fundamentally arresting multi‐scale mechanochemical failure, this strategy enables durable, high‐voltage Ni‐rich cathodes for safe, long‐life LIBs.