Improving acid-free and selective leaching of lithium from end-of-life LiFePO4 batteries using sodium persulfate: Impact of removing organic matter by thermal treatment in an inert atmosphere

Abstract

This study reports an acid-free, efficient, and selective method for Li leaching at room temperature from end-of-life (EoL) LiFePO₄ (LFP) batteries using sodium persulfate (Na₂S₂O₈) as a promising lixiviant. The objective of this study is to leach target metal, i.e., Li, as efficiently as possible while minimizing chemical consumption. First, valuable metal-containing materials called black powders (BPs) were recovered from actual EoL LFP batteries. Then, thermal treatment at 500 °C in a non-active, i.e., inert, atmosphere was employed to remove organic matter derived from the binder and electrolyte in the BPs, significantly enhancing leaching efficiency (LE). Under optimal conditions (0.4 M Na₂S₂O₈, 100 g/L pulp density, room temperature, and 30 min), Li was leached with an efficiency of 99.9% and a selectivity of more than 99.5% over Fe and P. This study highlights the importance of organic matter removal for achieving high Li leaching efficiency with minimal Na₂S₂O₈ consumption and suggests the potential of Na₂S₂O₈ for sustainable Li recovery in LFP hydrometallurgical processes.