A simple green method for in-situ selective extraction of Li from spent LiFePO4 batteries by synergistic effect of deep-eutectic solvent and ozone

Shujie Tang; Ziyue Yang; Mei Zhang; Min Guo

doi:10.1016/j.envres.2023.117393

A simple green method for in-situ selective extraction of Li from spent LiFePO₄ batteries by synergistic effect of deep-eutectic solvent and ozone

Environ Res. 2023 Dec 15;239(Pt 2):117393. doi: 10.1016/j.envres.2023.117393. Epub 2023 Oct 12.

Authors

Shujie Tang¹, Ziyue Yang¹, Mei Zhang¹, Min Guo²

Affiliations

¹ State Key Laboratory of Advanced Metallurgy, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, PR China.
² State Key Laboratory of Advanced Metallurgy, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, PR China. Electronic address: guomin@ustb.edu.cn.

PMID: 37838204
DOI: 10.1016/j.envres.2023.117393

Abstract

Efficient and clean extraction lithium (Li) from spent LiFePO₄ batteries (LIBs) still remains a challenge. In this paper, a green deep eutectic solvent (DES) based on ethylene glycol (EG) and choline chloride (CC), combined with ozone (O₃) from air source, realized highly selective leaching Li from LiFePO₄ in situ for the first time. The influence of experimental parameters on Li and Fe leaching efficiencies (η_Li, η_Fe) were studied by orthogonal and single-factor tests, and η_Li ≥ 92.2% while η_Fe ≤ 1.6% were obtained under the optimal conditions (6 h, 20 g/L, 8EG:1CC, 40 °C). The impurity Fe in the filtrate was completely precipitated as amorphous FePO₄·3H₂O after heating (150 °C, 0.5 h), achieving a pure Li-solution. The leaching mechanism elucidated that the synergistic effect (acidification, replacement and oxidation reaction) between the DES and O₃ determined the phase transition of Li and Fe, promoting the efficient selective extraction of Li and in-situ separation of Fe (FePO₄). The average η_Li and η_Fe were separately 85.4% and 2.0% after ten cycles of the 8EG:1CC, indicative of its' excellent reusability. Meanwhile, LiCl was recovered from the filtrate. This process avoided the use of strong acid/alkali and discharge of waste water, providing fresh perspectives on the green recovery of spent LiFePO₄ batteries.

Keywords: FePO(4); Green recovery; LiCl; Reusability; Spent LiFePO(4) batteries.

MeSH terms

Electric Power Supplies
Lithium*
Ozone*
Recycling / methods
Solvents

Substances

Lithium
Ozone
Solvents