• Fe3P bulk modification stabilizes the crystal lattice of Co-free lithium-rich manganese-based cathodes, mitigating capacity and voltage decay.
• The strategy promotes a robust cathode–electrolyte interphase and suppresses electrolyte decomposition, resulting in enhanced cycling stability.
• Modified LNMO delivers 98% capacity retention after 450 cycles at 1 C and 82% after 1000 cycles at 5 C, demonstrating excellent long-term durability.
• The facile spray-drying and high-temperature calcination integration offers a cost-effective, scalable route for high-energy-density LIB cathodes.