Recycling for Recovery of Critical Metals from LiCoO₂ Cathode Material Through Methanesulfonic Acid-Citric Acid Organic Leaching System

Growing demand for valuable battery materials and environmental issues from battery disposal make the recycling of spent lithium-ion batteries (LIBs) essential. Specifically, the green approaches using organic reagents have garnered many attentions for battery recycling. In this study, a synergetic organic leaching system using methanesulfonic acid (MSA) of strong organic acid and citric acid (CA) with good chelating ability was investigated to extract valuable metals from LiCoO₂. Hydrogen peroxide was used as a reducing agent to enhance leaching kinetics. Cobalt extraction of 98% and lithium extraction of 97 % were achieved in the optimized condition; 2.4M MSA, 1.6M CA, 1.0 vol% H₂O₂, S/L ratio 80 g/L, 85 °C, and 1 h. The optimal leaching condition of the MSA-CA mixed leaching system exhibited good applicability to various cathode scraps, such as LiCoO₂, LiNi_xMn_yCo_1-x-yO₂, and LiNi_xCo_yO₂. The dissolved Co and Li ions in the MSA-CA leachate were selectively recovered with high recovery efficiencies of 99 % and 97 % as Co₃O₄ and Li₃PO₄, respectively. The recovered Co₃O₄ and Li₃PO₄ were utilized to regenerate cathode materials. LiCoO₂ and LiFePO₄ were also synthesized through a solid-state reaction and hydrothermal method. The recycling process based on the MSA-CA-H₂O₂ synergetic leaching system was proposed, and it might be applied as a green and economical organic leaching system for the recycling of various types of spent LIBs.