Unlocking Low-Energy-Barrier Pathways via Monoclinic Acceptor Induction for Homogeneous Regeneration of Spent...

As the next-generation olivine-type cathode, high energy-density LiMn_xFe_{1- x}PO₄ (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 Li₃Fe₂(PO₄)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.