Efficient recovery of lithium as Li₂CO₃ and cobalt as Co₃O₄ from spent lithium-ion batteries after leaching with p-toluene sulfonic acid

Rechargeable lithium-ion batteries (LIBs) have been widely used in consumer electronics and electric vehicles. In terms of environmental restrictions and circular economy, proper treatment of spent LIBs is of great significance for achieving sustainable development. In this study, organic p-toluene sulfonic acid (PTSA) was employed to recycle valuable Li and Co elements from the spent LIBs for production of battery raw materials (e.g. Li₂CO₃ and Co₃O₄). Operation parameters such as PTSA concentration, hydrogen peroxide (H₂O₂) concentration, solid-to-liquid ratio, leaching temperature and leaching time, were systematically investigated. Under the optimal conditions (0.9 vol% H₂O₂, 1.5 mol L⁻¹ PTSA, 30 g L⁻¹ solid-to-liquid ratio, 80 °C, and 60 min), the leaching efficiencies of commercial LiCoO₂ could reach ∼100% and 99% for Li and Co, respectively, while the corresponding values were about 95% and 93% for the spent LiCoO₂. In addition, the selective precipitation of Co-rich compounds in cooled leachate allowed an effective separation of Co from the mixture. The high recovery yield of Co₃O₄ and Li₂CO₃ demonstrated the great potential of the PTSA-assisted leaching strategy in hydrometallurgical recycling of the spent LIBs for practical applications. Overall, this proposed recovery process is simple, efficient, and environmentally friendly and is of vital importance for rational treatment of spent LIBs.