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.