Abstract
The rapid growth in lithium iron phosphate (LFP) battery deployment, driven by electric vehicle manufacturers such as BYD, Tesla, Ford, and Volkswagen, has created an urgent need for recycling strategies tailored to phosphate-based cathodes. Unlike nickel- and cobalt-containing chemistries, LFP batteries present distinct processing challenges and opportunities, particularly for selective lithium recovery and closed-loop material reuse. Developing efficient, low-impact hydrometallurgical routes for LFP recycling is therefore a priority for both industry and policymakers focused on critical-materials security and sustainable battery supply chains. This study systematically evaluates selective lithium extraction from LFP-type black mass using a range of inorganic and organic acid systems in the presence of hydrogen peroxide. Five acid–oxidant systems were assessed to identify conditions that balance extraction efficiency, selectivity, reagent cost, and operational safety. Comprehensive materials characterization confirmed that the feed consisted primarily of crystalline LiFePO4 and graphitic carbon, with surface-enriched lithium and fluoride species influencing leaching behavior. High lithium recoveries (>95%) were achieved using sulfuric, hydrochloric, nitric, and acetic acid systems, while maintaining minimal co-dissolution of iron and phosphorus. In contrast, oxalic acid, although effective for lithium dissolution, showed reduced selectivity due to strong iron complexation. The addition of hydrogen peroxide was found to be critical in enhancing both lithium recovery and selectivity by promoting iron oxidation and stabilization as insoluble phosphate phases. From an industrial perspective, process evaluation indicates that sulfuric acid remains the lowest-cost option, while acetic and hydrochloric acids provide an attractive balance of selectivity, efficiency, and safety. Importantly, the solid residues generated under selective leaching conditions were enriched in FePO4, making them suitable for direct relithiation and cathode material regeneration. This work provides a practical framework for evaluating leaching systems in LFP battery recycling and demonstrates that selective lithium recovery can be achieved under moderate conditions with reduced environmental impact. The findings support the development of green, closed-loop hydrometallurgical processes for phosphate-based lithium-ion batteries, strengthening critical-materials circularity and supply-chain resilience.