Room Temperature Efficient Regeneration of Spent LiFePO4 by Direct Chemical Lithiation

The exponential production of lithium-ion batteries for electric vehicles (EVs) and electronic applications leads to the creation of a huge stock of batteries at the end of life. Considering the current economic, geopolitical and environmental context, the recycling of these spent batteries is becoming an urgent need in order to mitigate environmental pollution and limit the waste of valuable and critical resources 1 . In this work, we report a rewarding direct recycling process of spent LiFePO 4 cathode material by direct chemical lithiation in solution 2 . After safe opening of the spent commercial battery, a structural, morphological, spectroscopic and electrochemical characterization of the spent LFP cathode was carried out to identify the reason(s) of battery failure. The results obtained by XRD (Fig 1a) and Mössbauer spectroscopy (Fig 1b) show that the loss of lithium in the cathode (up to 50%) consumed during formation and growth of the SEI during cycling, is the major reason of the end of life of these batteries, in total agreement with the literature 3 . To address the lithium shortage problem, a recycling process via direct chemical lithiation in organic solution at room temperature of the LFP cathode has been implemented. Lithium iodide (LiI) dissolved in several solvents such as acetonitrile, cyclohexane, ethanol, DMSO, methanol and propan-1,2-diol was used as both the reductant and the lithiation agent. The best results were obtained with the cathode regenerated in ethanol, which is also the most captivating and environmentally friendly solvent. The different characterizations of this regenerated cathode allow evaluating the efficiency of the regeneration process. Mössbauer spectroscopy (Fig. 2a) confirms the total reduction of Fe III PO 4 to LiFe II PO 4 , while electrochemical characterization (Fig. 2b) shows encouraging properties with a reversible capacity of ~168 mAh/g for the regenerated LFP. References: (1) Neumann, J. et al. Recycling of Lithium‐Ion Batteries—Current State of the Art, Circular Economy, and Next Generation Recycling . Adv. Energy Mater. 12 , 2102917 (2022). (2) Ouaneche, T. et al. Room temperature efficient regeneration of spent LiFePO 4 by direct chemical lithiation. 579 , J. Power Sources (2023) 233248. (3) Zhou, S. et al. Direct recovery of scrapped LiFePO 4 by a green and low-cost electrochemical re-lithiation method. Green Chem. 24 , 6278–6286 (2022). Figure 1 : a) XRD pattern and b) Mössbauer spectrum of the recovered Li x FePO 4 powder. Figure 2 : a) Mössbauer spectrum and b) Charge-discharge galvanostatic curve at C/10 of the regenerated LFP cathode as positive electrode vs . Li + /Li 0 and its derivative curve. Figure 1