Supramolecular Self‐Assembly Enables Controlled Lithium Replenishment Toward High‐Performance and Sustainable Regeneration of Spent LiFePO ₄ Batteries

ABSTRACT With the rapid expansion of lithium–ion battery deployment, spent LiFePO 4 (LFP) regeneration is vital for closing material loops. However, in conventional solid‐state regeneration, limited solid–solid contact and the premature formation of a dense conductive carbon layer hinder the effective coordination of lithium replenishment, structural defect repair, and interfacial reconstruction, thereby limiting lithium utilization efficiency and structural restoration. This paper presents a self‐assembled supramolecular (SAS) regeneration system spontaneously formed from trithiocyanuric acid (TMT) and lithium acetate (CH 3 COOLi). Through Li–S coordination and hydrogen‐bonding interactions, the precursor self‐assembles into an ordered supramolecular architecture that regulates the thermal evolution of the solid‐state regeneration process. Unlike the independent thermal decomposition of mechanically mixed precursors in conventional solid‐state regeneration, the ordered supramolecular architecture regulates the reaction sequence, enabling lithium to preferentially enter the LiFePO 4 lattice before the formation of a dense conductive carbon layer, thereby achieving efficient lithium replenishment and structural restoration. Subsequently, an in situ generated N/S co‐doped conductive carbon layer elevates interfacial conductivity of regenerated LFP. The regenerated cathode delivers 160.3 mAh g − 1 (0.1 C) and 143.0 mAh g − 1 (1 C), maintaining 88% capacity over 500 cycles at 1 C, while the pouch cell exhibits 81% capacity retention after 500 cycles at 0.5 C.