Unlocking Low‐Energy‐Barrier Pathways via Monoclinic Acceptor Induction for Homogeneous Regeneration of Spent LiMn <i> _x </i> Fe _1‐ <i> _x </i> PO ₄ Cathodes

Abstract

ABSTRACT As the next‐generation olivine‐type cathode, high energy‐density LiMn x Fe 1‐ x PO 4 (LMFP) would reach end‐of‐life and produces numerous retired materials, thus exploring its effective recycling technology is urgent. However, suffered from the differences in oxidation energy barriers, synchronous regulation of Mn/Fe phases could be hardly achieved in direct regeneration, resulting in spent LMFP difficult to be repaired. For solving the problems above, a monoclinic lattice‐induction strategy is proposed. Supported by introducing monoclinic‐structured Li 3 Fe 2 (PO 4 ) 3 as acceptors, the reaction energy of phase transition can be effectively reduced, finally alleviating the “rivet” effect of Mn. Benefiting from effort above, atomic‐level homogeneity of Fe/Mn distribution is achieved in regenerated samples, along with the alleviation of strain‐stress concentration. Specially, the lower ratio of anti‐sites defects of repaired LMFP is controlled, accelerating the Li‐diffusion along (010) direction. Importantly, Mn─O bonds are reinforced, suppressing Mn‐dissolving behaviors and improving the structural stability. As lithium‐storage cathode, the as‐optimized sample displays a capacity of 145.5 mAh g −1 at 1.0 C, even achieving 91.61% capacity retention ratio after 1500 loops. Given this, monoclinic lattice‐induction strategy is expected to provide significant guidance for large‐scale LMFP recycling.