Enhanced Stability and Performance of High‐Voltage LNMO Cathodes with Dual‐Anion Niobium Oxyfluoride Coating

Abstract High energy cathodes with low environmental impact are critical for the development of next‐generation lithium‐ion batteries (LIBs). Lithium nickel manganese oxide (LNMO) cathode is a promising cathode candidate due to its high operating potential (≈4.7 V vs Li ⁺ /Li), energy density (≈650 Wh kg ⁻¹ ), thermal stability, and cost‐effectiveness. However, it suffers from interfacial degradation and processing limitations. This work pioneers the implementation of niobium oxyfluoride as a multifunctional protective coating on LNMO for high‐voltage LIBs applications. A conformal, ultrathin NbO ₂ F layer (≈5 nm) is precisely engineered via atomic layer deposition, to improve cathode stability. The coating's dual‐anion architecture (F ⁻ and O ²⁻ ) and chemically inert Nb ⁵⁺ state offers improved resistance to hydrofluoric acid‐induced corrosion, suppressing transition‐metal dissolution, and mitigating capacity degradation. In half‐cell configuration, the niobium oxyfluoride coated LNMO (NbO ₂ F@LNMO) versus Li/Li ⁺ achieves >91% capacity retention after 500 cycles. At high temperature (60 °C), the cathode demonstrates 92.8% retention at 0.1 C and 550 Wh kg ⁻¹ energy density after 100 cycles. Full‐cell comprising the NbO ₂ F@LNMO cathode exhibits >94% capacity retention after 100 cycles. Additionally, the NbO ₂ F@LNMO cathode exhibits a remarkable resilience under high‐humidity environments, underscoring its robust long‐term storage capabilities and processability. This approach provides a pathway toward practical LNMO cathodes for high‐voltage, stable, and cost effective LIBs.