Recovery of Li and Mn by H3PO4-citric acid leaching from spent LiMn2O4 batteries for synthesis of LiMn0.75Fe0.25PO4

Although hydrometallurgy is the primary method for recycling spent lithium-ion batteries (LIBs), handling the waste liquid produced during the leaching process remains a challenge due to the additional procedures and costs involved. This study presents an efficient, closed-loop recycling process for spent LiMn 2 O 4 (LMO) batteries. The waste LMO powders were initially leached with H 3 PO 4 and citric acid (CA) to obtain the leachate containing Li + , Mn 2+ , PO 4 3− and citrate ions. The metal ions leached into the solution are complexed by CA, achieving complete leaching of LMO. The H 3 PO 4 and CA provide both PO 4 3− and carbon sources for subsequent product preparation, minimizing resource waste and secondary pollution. The molar ratio of Li:Mn:Fe:PO 4 3− in the leachate was adjusted to 1:0.75:0.25:1, and LiMn 0.75 Fe 0.25 PO 4 (LMFP) with excellent performance was regenerated by spray drying and calcination. The regenerated LMFP-650 exhibited a capacity retention rate of 89.7% after 500 cycles, significantly improving the structural stability and cycling performance of LMO. This green, closed-loop recycling process prevents secondary pollution and promotes the sustainable development of the battery industry.