Mechanochemical Regulating Competitive Phase Transformation of Fe 3 (PO 4 ) 2 Toward Industrial‐Grade Regenerated LiFePO 4

ABSTRACT Attracted by short‐process and uniform regenerated properties, oxidation‐homogenization then reduction‐reconstruction of spent LiFePO 4 (SLFP) has been successfully industrialized. Two types of SLFP exist: production scrap and cycled retired battery materials. Nevertheless, these treatments enable efficient regeneration of the former, yet fail to restore the latter effectively, always with unsatisfactory energy‐storage properties. From our experience, the introduced mechanochemical behaviors (MCB) would induce the tailoring of their properties. Herein, through the controlling of MCB, the evolution of physical‐chemical properties is revealed during the full‐loop process. MCB would induce the exposure of the metastable Li 1−x FePO 4 transition region. Clearly, along with the competition of carbon and O 2 , they were transformed into Fe 3 (PO 4 ) 2 intermediate coated with a dense Fe 2 O 3 layer, bringing about the uneven carbon layers and lattice stress distribution. By replacing ball milling with jet milling, excessive mechanical stress is avoided. The as‐optimized sample deliver a capacity of 148.2 mAh g −1 after 200 cycles at 1.0 C and 108.4 mAh g −1 after 1000 cycles at 5.0 C. Furthermore, kg‐scale experiments are conducted to prove the practical reliability of recycling manners. Thus, this work is expected to elucidate the full‐loop regeneration mechanism of cycled retired battery materials, meanwhile providing the significant treatment strategy for practical industry production.