Radial multiphase integration boosting capacity and stability for low-nickel cathodes
Nickel-rich layered cathodes (Ni≥80%) offer high discharge capacity for lithium-ion batteries but face sustainability and structural stability challenges. This study presents a radially multiphase integrated low-nickel (Ni<60%) cathode material, Li(Li0.05Ni0.57Mn0.31Co0.07)O2 (LNC), which achieves high capacity and long-term cycling stability by leveraging highly reversible anionic redox chemistry. The cathode comprises three distinct radial phases: an outermost epitaxial rock-salt phase with lithium-percolation channels, an intermediate lithium-rich manganese-rich phase with delocalized superlattice ordering, and an inner nickel-rich layered phase. The rock-salt phase suppresses interfacial side reactions and structural degradation, while the superlattice enhances lattice oxygen redox reversibility, as evidenced by resonant inelastic X-ray scattering (mRIXS) showing persistent spectral features at 4.5 V even after 100 cycles. The inner nickel-rich phase provides high discharge capacity via nickel-ion redox. This synergistic integration minimizes lattice variations and nickel oxidation state changes during cycling, as demonstrated by in-situ high-energy X-ray diffraction. Compared to commercial N60, N70, N80, and N90 cathodes, LNC delivers superior discharge capacity, cycling stability, and rate performance while reducing nickel dependence, offering a sustainable pathway for high-energy-density batteries.