From Modification to Regeneration: Synergistic Advances in Olivine LiMn _x Fe _1−x PO ₄ Cathodes and Closed‐Loop Recycling of Spent LiFePO ₄

ABSTRACT Olivine‐type LiMn x Fe 1−x PO 4 (LMFP) has emerged as a next‐generation cathode for lithium‐ion batteries (LIBs), synergistically combining the high safety and low cost of LiFePO 4 (LFP) with a theoretical energy density of 655 Wh kg − 1 (as exemplified by LiMn 0.6 Fe 0.4 PO 4 ). However, its practical application is constrained by intrinsically low electronic conductivity, sluggish Li + diffusion, and Mn 3 + ‐induced Jahn–Teller distortion. These bottlenecks also mirror the degradation mechanisms of spent LFP (S‐LFP), positioning LMFP modification principles as a blueprint for closed‐loop recycling. This review systematically elucidates the crystal structure and charge‐transport pathways of LMFP, followed by an in‐depth analysis of three core optimization strategies—surface engineering, bulk doping, and structural design—supported by experimental and theoretical insights. Building upon this mechanistic foundation, the review extends the discussion to sustainable regeneration, proposing a unified “diagnosis–modification–utilization” paradigm that bridges LMFP advancement with S‐LFP upcycling. Representative recycling pathways, including direct regeneration, performance upgrading to LMFP, and cross‐system repurposing, are comparatively assessed in terms of efficiency and scalability. Finally, emerging directions such as high‐entropy doping, electrolyte engineering, and interface stabilization are highlighted to guide the future commercialization of LMFP and promote a circular, value‐added battery ecosystem.