Robust interfacial layer stabilizing phase transition of high-voltage spinel cathode

High-voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) stands out as a promising candidate for next-generation high-performance lithium-ion batteries, offering high energy density and cost advantages. Nevertheless, its practical application is hindered by critical challenges, such as surface instability and detrimental side reactions with electrolytes at high voltages, which lead to rapid capacity fading. Herein, an ultrathin, dense LiF interfacial layer (∼2 nm) is successfully constructed on the surface of the truncated octahedral LNMO particles (F-LNMO) via a facile fluorination approach. This modification strategy effectively suppresses lattice oxygen loss and direct interaction between the electrolyte and highly reactive Ni/Mn species, drives the critical shift in the Li 1 → Li 0.5 phase transition pathway from a two-phase reaction to a more stable solid-solution reaction, and triggers the formation of the dense and uniform cathode-electrolyte interphase (CEI) layer during cycling, thereby reducing transition metal dissolution. The as-prepared F-LNMO material demonstrates exceptional cycling stability, with a remarkable capacity retention of 92.7% after 300 cycles, and improved ion diffusion coefficient of 8.92 × 10 -10 cm 2 s -1 . These findings highlight the critical role of artificial interfacial engineering in optimizing high-energy-density LNMO cathode materials with improved stability and rate performance. An ultrathin (∼2 nm) dense LiF interfacial layer is successfully constructed on truncated octahedral LNMO surface via fluorination strategy, which effectively suppresses lattice oxygen loss and transition metal dissolution, while enabling more stable phase transition. The generated dense and homogeneous CEI layer during cycling further significantly enhances cycling stability of LNMO cathode, achieving 92.7% capacity retention after 300 cycles. • Ultrathin dense interfacial layer is constructed onto LNMO by facile fluorination. • Modified LNMO demonstrates remarkable capacity retention of 92.7% after 300 cycles. • Interfacial layer induces a transition towards more stable solid-solution reaction. • Dense, uniform CEI layer generated during cycling further mitigates TM dissolution.