E-pH diagram-guided low-temperature short-time sulfuric acid leaching for efficient recovery of lithium and iron from high-aluminum LiFePO4 black powder

The recycling of cathode materials in waste lithium-ion batteries is of great significance to resource utilization and environmental protection. However, few studies have addressed the challenges posed by high-aluminum LiFePO 4 black powder (HALFP-BP) resulting from inadequate pre-treatment. This study proposes a low-temperature short-time sulfuric acid leaching method based on thermodynamic analysis of E-pH diagrams. Under optimized conditions, the leaching efficiencies of Li and Fe reached 99 %, while 86 % of Al was selectively removed. Furthermore, the guiding role of E-pH diagram in the recovery process and the chemical reactions and Gibbs free energy analysis during the acid leaching process were analyzed. It revealed that the dissolution kinetics inhibition of the dense Al 2 O 3 film on the surface of aluminum impurities in the sulfuric acid system was the key to achieving selective separation. This method provides an energy-saving and efficient solution for the resource utilization of the HALFP-BP.