J. Mater. Sci. Technol. ›› 2026, Vol. 250: 98-107.DOI: 10.1016/j.jmst.2025.05.048

• Research article • Previous Articles     Next Articles

Lactic acid-ethylene glycol system driven materials stripping for efficient and eco-friendly recycling of spent LiFePO4 cathode materials

Tiansheng Wanga,c,d,e,f,1, Wen Yuc,d,e,f,1, Guanjun Chenf,1, Chaochao Gaoc,d,e,f, Jichuan Zhangc,d,e,f, Yixin Linc,d,e,f, Mi Wangc,d,e,f, Jie Xub,*, Chao Yanga,*, Jiaheng Zhangc,d,e,f,g,*   

  1. aSchool of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;
    bSchool of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China;
    cSchool of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;
    dResearch Centre of Printed Flexible Electronics, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;
    eSauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;
    fShenzhen Shinehigh Innovation Technology Ltd., Shenzhen 518055, China;
    gDepartment of Chemistry, University of Idaho, ID 83844-2343, USA
  • Received:2025-01-24 Revised:2025-04-28 Accepted:2025-05-02 Published:2026-04-10 Online:2025-06-30
  • Contact: *E-mail addresses: xjhit@hit.edu.cn (J. Xu), xyyang@hit.edu.cn (C. Yang), zhangjiaheng@hit.edu.cn (J. Zhang).
  • About author:1These authors contributed equally to this work.

Abstract: Recycling spent lithium-ion batteries (LIBs) is essential for establishing a closed-loop LIBs industry. In this study, we introduce an environmentally friendly and cost-effective deep eutectic solvent (DES) synthesized from lactic acid (LA) and ethylene glycol (EG). This solvent achieves a cathode separation efficiency exceeding 99.98 % for spent LiFePO4 (LFP) materials within just 4 min at room temperature, with negligible metal loss. The separated LFP demonstrates high purity and structural stability, while the recycled aluminum (Al) foil remains intact and free of corrosion. Mechanistic analysis reveals that the DES reacts with the Al foil and passivates the polyvinylidene fluoride binder, facilitating efficient separation. Furthermore, the formation of a Al(LA)3 passivation layer on the Al surface effectively prevents further corrosion. This DES direct recycling method enables the repair and restoration of battery electrodes, simplifying the recycling process while reducing costs and environmental impact. After regeneration treatment, the regenerated LFP exhibits excellent electrochemical performance, with a reversible capacity of 96.61 mAh g-1 at a 5 C rate, comparable to that of commercial LFP (97.65 mAh g-1). This straightforward separation strategy offers a sustainable and economical solution for recycling spent LIBs.

Key words: Spent lithium-ion batteries, Direct recycling, Deep eutectic solvent, Efficient separation, Regenerated LiFePO4