Jun Ma,Ziyang Xu,Tianshun Yao,Zhe Chen,Xin Liu,Quan Sun,Yachao Jin,Li Song,Ming-Dao Zhang
Waste LiFePO4 (LFP) batteries can be harmful to the environment and lead to waste of resources if not properly disposed of. In this study, an efficient and environmentally friendly method for solid-phase recycling waste LFP cathode material (W-LFP) is proposed. Most of the impurities in the W-LFP are removed by air firing. The regenerated LFP is then obtained by adding lithium carbonate and triethanolamine for repair during heat treatment. The addition of triethanolamine converts Fe3+ to Fe2+ and also allows the formation of an N-doped modified carbon layer on the surface of the LFP particles, which improves the electrochemical properties of the regenerated material. Physical characterization and electrochemical tests are used to investigate the attenuation and regeneration mechanism of LFP. The regenerated LFP possesses a high specific discharge capacity (152.87 mAh g–1 at 0.2 C), which is about 95.32% of the commercial LFP, and the capacity retention rate is 88.52% after 600 cycles at 1 C. It is worth noting that we do not use solvents such as acids and alkalis in the regeneration process, thus avoiding the generation of large quantities of acid and alkaline waste liquids, which is friendly to the environment. This solid-phase regeneration process offers a promising method for the future recycling of used LFP batteries because of its simplicity, environmental friendliness, and high efficiency.
Peipei Gao,Wei Wang,Tao Tang,Rongge Hu,Mengyun Liu,Hanjie Wen,Ziyuan Zhou,Zhiqi Liu
The rapid expansion in the demand for LiFePO 4 (LFP) batteries has created a pressing need for recycling waste LFP batteries. However, the direct extraction of lithium from their acid leachate remains a significant challenge. This study developed a novel extraction system using tributyl phosphate (TBP) as extractant and ionic liquids (ILs) as co-extractant for selective recovery of Li + from H 2 SO 4 leachate of waste LFP cathode. The single-factor experiment results demonstrated that TBP-[C 4 mim][NTF 2 ] (1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide) exhibited higher lithium extraction efficiency under acidic conditions compared to TBP-[C 4 mim][PF 6 ] (1-Butyl-3-methylimidazolium hexafluorophosphate). Moreover, a four-stage cross-current extraction process utilizing the TBP-[C 4 mim][NTF 2 ] system was demonstrated to efficiently and selectively extract lithium from a real H 2 SO 4 leachate, achieving extraction efficiency and separation factor of 92.39% and 197.95, respectively. Mechanism insights from Fourier transform infrared spectroscopy (FT-IR) and theoretical calculations indicate that cationic exchange and a synergistic effect between TBP and IL enhance the selective extraction of lithium. The cation of IL (C 4 mim + ) enters aqueous phase, and Li + are extracted into organic phase in the form of Li + -TBP-[NTF 2 ] - with a larger binding energy. Furthermore, five cycles of extraction and stripping experiments not only yielded a lithium-enriched solution but also demonstrated the excellent stability of the TBP-[C 4 mim][NTF 2 ]. Finally, the Li + was ultimately recovered as high-purity Li 3 PO 4 via the chemical precipitation method. This study provides theoretical and technical references for efficient extraction of lithium from LFP acid leachate, which is crucial for comprehensive utilization of waste LFP cathodes.
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