Sustainable Revival of Spent Lithium Iron Phosphate Cathodes in Li‐Ion Batteries: Recycling and Surface Engineering Approaches

This review systematically examines recent advancements and ongoing challenges in the recycling of lithium iron phosphate (LFP) cathode materials, including hydrometallurgical, pyrometallurgical, and direct recycling approaches. Thermodynamic and kinetic characteristics, lithium recovery mechanisms, and lithium recovery pathways of each method are critically analyzed. Recent studies of hydrometallurgy presented high lithium recovery efficiencies approaching 95–99%. Regenerated LFP species have been investigated recently to reach 140–160 mAh g −1 in capacity that are very close to commercial LFP cathode materials. A comparative evaluation of their economic value and environmental effects is also conducted to examine their industrial feasibility. It also discusses surface engineering and modification strategies after recycling, including carbon, polymer, and metal/metal oxide coatings, aiming at restoring or then enhancing the electrochemical performance of regenerated LFP by boosting the electron conductivity and Li diffusion. By integrating insights from recycling technologies and materials engineering, this review offers a holistic outlook on transforming spent LFP into high‐performance cathode materials, thereby providing valuable guidance for sustainable battery development and circular economy initiatives.