Sequential separation and recovery of Li, Mn, Co, and Ni from spent lithium-ion batteries using integrated solvent extraction and precipitation

Abstract

The growing demand for lithium and critical elements in lithium-ion battery (LIB) production highlights the urgent need for recycling to support low-carbon transport and energy storage. Here, we present an integrated hydrometallurgical process combining optimized acid leaching with a multi-stage separation cascade, achieving > 98 % recovery of Li, Co, Mn, and Ni from spent LIB cathodes. Almost quantitative leaching of Li, Co, Mn and Ni from LIB powder was achieved utilizing 3.0 M H₂SO₄ with 10 vol% H₂O₂ at 85℃ for 1 h. Through precise control of environmental factors such as pH, extractant concentrations and O:A ratios, the process achieves exceptional separation efficiency for all metals in LIBs. The separation strategy employs: (i) a novel Primene JM-T/Cyanex 272 synergistic system that selectively extracts > 90 % of Co/Mn/Ni as M(L)₂·2RNH₃⁺SO₄²⁻ (M = Co, Mn, Ni) complexes while leaving Li in raffinate; (ii) P204 extractant exhibiting exceptional Mn selectivity from Co/Ni (>99 % Mn extraction), with slope analysis confirming Mn(HL₂)₂ as the dominant species; and (iii) Cyanex 272 achieving > 98 % Co extraction (as Co(HL₂)₂) with minimal Ni co-extraction (<10 %). Besides, XPS, XRD, SEM-EDS analysis confirmed the achievement of high-purity (＞98 %) precipitates of Li₂CO₃, MnCO₃, Co(OH)₂, and NiCO₃. Futhermore, all extractants exhibit excellent reusability over 10 cycles. Thus, this study presents a lithium-first recovery strategy, with sequential separation and extraction of Mn, Co, and Ni, demonstrating both process efficiency and commercial potential for LIB recycling.