Controllable phase-reconstruction strategy for LiFePO4 homogeneous regeneration: reaction mechanism, characterization and prospect

The growing volume of end-of-life lithium-ion batteries (LIBs) represents both an urgent environmental challenge and a critical resource opportunity, especially for cathode materials. Among commercial cathodes, LiFePO₄ (LFP) dominates the market due to its favorable properties; thus, a substantial amount of LFP cathode materials is expected to retire in the near future. The conventional hydrometallurgical method suffers from high costs and serious pollution. Direct regeneration technologies, especially solid-state sintering, provide a more efficient and environmentally benign alternative by repairing cathode structures through high-temperature solid-phase reactions without extra chemical reagents. Traditional solid-state sintering faces challenges in processing spent LFP from diverse sources, struggling to achieve the homogenization of physical–chemical properties and electrochemical performance. To address the limitations above, phase homogenization with a lattice reconstruction strategy has been investigated, which can enable effective lattice reconstruction and microstructural homogenization, demonstrating robust adaptability to spent samples from variable sources. This review systematically summarizes the mechanisms, detailed steps, characterization techniques, and advances in pre-oxidation optimization (including ion-doping and coated carbon layer modification), as well as future research directions for sustainable LFP recycling. Given this, this review is expected to offer theoretical guidance for achieving homogeneous regeneration of LFP cathode.