LiCoO 2 /LiMn 0.6 Fe 0.4 PO 4 Composite Cathode with Enhanced Interfacial Structure Enables Long‐Life Lithium‐Ion Batteries

ABSTRACT Extending the cycle life of LiCoO 2 (LCO) cathodes under elevated cutoff voltages remains a critical challenge for lithium‐ion batteries, as accelerated degradation is often governed by reaction heterogeneity and interfacial instability. Herein, we report a composite cathode composed of micron‐sized LCO and nanoscale LiMn 0.6 Fe 0.4 PO 4 , in which LMFP functions as a kinetically robust and electrochemically active component. Without invoking specific heterostructures, the optimized composite exhibits outstanding cycling stability at 4.45 V, retaining 94.2% of its initial capacity after 300 cycles at 1 C/1 C and 91.4% after 300 cycles at 3 C/3 C. Even at 4.6 V, the composite consistently outperforms pristine LCO. Importantly, pouch cells paired with a prelithiated silicon‐carbon anode deliver an energy density of 250 Wh kg −1 and maintain 81.8% capacity retention over 400 cycles. These results highlight a practical composite cathode strategy for prolonging the service life of LCO‐based batteries within realistic voltage windows, offering a scalable pathway toward durable high‐energy lithium‐ion systems.