Value-added recycling of spent LiFePO4 by a FeCl3 leaching-spray pyrolysis approach

Abstract

Traditional recycling technologies for spent lithium iron phosphate (LiFePO4, LFP) usually suffer from issues such as complex procedures, heavy chemical consumption, and limited economic viability. Herein, we propose a method combining FeCl3 leaching and spray pyrolysis for the high-value-added recycling of spent LFP. Using FeCl3 as leaching agent, over 99 % of Li is selectively leached out within 30 min with a solid-liquid ratio up to 300 g L−1. The resulting leaching residue (FePO4) serves as a precursor for the synthesis of new LFP. Subsequently, the Li and Fe-containing leachate undergoes a spray pyrolysis process, yielding a pyrolysis powder comprising LiCl and Fe2O3. Through a water-leaching procedure, the separation of LiCl and Fe2O3 is achieved based on their distinct solubility in water. The resulting high-purity LiCl solution and Fe2O3 residue are directly utilizable for producing battery-grade Li2CO3 and LFP cathodes, respectively. LFP/C cathodes, synthesized using the recovered Li2CO3 and FePO4 precursor, exhibit an impressive 99.8 % capacity retention after 200 cycles at a 1C rate. This method holds great economic and environmental benefits by producing high-value-added products while avoiding the consumption of acids or alkalis.