Radical Anion‐Driven Electron‐Ion Coupled Repair Chemistry for Direct Regeneration of Degraded LiFePO ₄ Cathodes

Abstract

ABSTRACT Direct regeneration of spent LiFePO 4 (LFP) cathodes is a sustainable alternative to conventional recycling methods. However, poor remediation efficiency and complex processes limit its application. Here, we develop a room‐temperature liquid‐phase strategy based on a deep green lithium naphthalenide (Li‐Naph) solution. This strategy utilizes radical anion‐driven electron‐ion coupling remediation chemistry to integrate electron donors, lithium transport, and surface reconstruction within a single solution‐phase platform. The strongly reducing naphthalene radical anion enables spontaneous electron transfer at ambient conditions, efficiently converting Fe 3+ back to Fe 2+ , while promoting surface lithium enrichment through coupled electron–ion interactions. Subsequent annealing allows the enriched lithium to diffuse into lithium vacancies, while the organic residues undergo in situ carbonization into a conformal conductive shell, achieving synergistic bulk repair and surface reconstruction. This chemistry fully restores the olivine framework, suppresses Fe–Li anti‐site defects, and markedly enhances Li + transport kinetics. The regenerated cathode delivers a high initial capacity of 140.1 mAh g −1 and retains 92% capacity after 650 cycles at 1C, even maintaining excellent stability at a high rate of 5C. Importantly, the strategy remains effective for severely degraded cathodes, highlighting the broad applicability of radical‐anion‐driven repair chemistry.