Enhancing Ultrahigh-Rate Stability of LiNi _0.5 Mn _1.5 O ₄ Cathode Via Interfacial Stabilization and Phase Transition Suppression

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) is a promising high-voltage cathode for low-cost and high-power lithium-ion batteries. However, issues such as interfacial side reactions, Mn dissolution, and two-phase transition during cycling hinder its commercialization by causing structural degradation and capacity fading. Here, we demonstrate a dual-functional modification strategy that simultaneously stabilizes LNMO interface and suppresses the two-phase transition. This is realized by constructing a stable CeO₂ surface layer while incorporating a fraction of Ce into the bulk 16d sites. A series of characterizations confirm that the CeO₂ layer mitigates Mn dissolution and HF corrosion, whereas Ce incorporation into the bulk 16d site stabilizes the lattice structure and facilitates Li⁺ diffusion. As a result, the dual-functional modified LNMO exhibits exceptional ultrahigh-rate performance, delivering 117.8 mAh g^-1 at 10 C with 96.1% retention after 500 cycles, far outperforming the pristine material (71.6%). Even after 1000 cycles, 88.8% capacity retention is preserved. This study establishes an effective interfacial stabilization and phase transition suppression strategy for high-voltage cathodes, offering valuable insights into the development of next-generation fast-charging lithium-ion batteries.