Ultrahigh‐Ni layered oxide cathodes (Ni ≥ 90%) are leading candidates for high‐energy lithium‐ion batteries (LIBs) because they deliver high reversible capacity while reducing cobalt reliance. However, pushing Ni into the ultrahigh regime amplifies strongly coupled degradation pathways, including Li/Ni cation mixing, lattice‐oxygen instability and oxygen release, surface reconstruction with cathode–electrolyte interphase (CEI) growth, transition‐metal dissolution and cathode–anode cross‐talk, as well as chemo‐mechanical damage. These processes synergistically accelerate impedance rise, gas generation, capacity decay, and safety risks, particularly under high‐voltage operation, elevated temperature, and full‐cell conditions. In this review, we consolidate the mechanistic “degradation cascade” in ultrahigh‐Ni layered oxides and critically assess stabilization strategies spanning materials and electrode engineering. We discuss bulk regulation (microstructure control, defect/dopant engineering, and gradient architectures), surface/interphase engineering (coatings, artificial CEI, and electrolyte/additive co‐optimization), and electrode‐level approaches (single‐crystal particles, tailored architectures, and processing/compaction optimization). We further highlight advanced diagnostics linking oxygen chemistry, interphase evolution, and stress accumulation to electrochemical behavior, and propose practical benchmarking metrics and reporting guidelines for durable, safer high‐energy LIBs.
Yu et al. (Mon,) studied this question.