An Electrochemical Separation Process for Producing Battery-Grade FePO4 and LiOH·H2O Raw Materials from Spent LiFePO4

Abstract Along with lithium iron phosphate (LFP) batteries emerging as the core energy storage technology, the recycling of spent LFP batteries has become a critical challenge in establishing a sustainable energy storage industry. Current industrially deployed technologies typically involve mechanical separation to obtain black mass (S-LFP), followed by H2SO4 leaching, pH adjustment with NaOH to precipitate FePO4, and subsequent recovery of Li2CO3 via Na2CO3 addition. However, the conventional processes suffer from high consumption of alkalis and acids, coupled with the formation of the Na2SO4 byproduct that increases wastewater treatment investment, leading to elevated operational costs. Herein, we propose a novel electrochemical separation strategy that realizes directly separating lithium and iron from S-LFP leachate without chemical consumption. Strikingly, it was observed that the leaching efficiencies of Li and Fe reach 98.5% and 97.53%, respectively, using inexpensive HCl under conditions of 0.5 M, 25 g/L solid–liquid ratio, and room temperature. More importantly, the Li and Fe in the leachate are directly separated into battery-grade FePO4 solid and LiOH solution by an electrochemical cell without any additional chemical consumption. Overall, this work presents a chemical-free strategy for the selective separation of iron and lithium from S-LFP leachate to produce high-purity products.