Sustainable upcycling of mixed spent cathodes to a high-voltage polyanionic cathode material.

Ji, Guanjun; Tang, Di; Wang, Junxiong; Liang, Zheng; Ji, Haocheng; Ma, Jun; Zhuang, Zhaofeng; Liu, Song et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Sustainable battery recycling is essential for achieving resource conservation and alleviating environmental issues. Many open/closed-loop strategies for critical metal recycling or direct recovery aim at a single component, and the reuse of mixed cathode materials is a significant challenge. To address this barrier, here we propose an upcycling strategy for spent LiFePO<sub>4</sub> and Mn-rich cathodes by structural design and transition metal replacement, for which uses a green deep eutectic solvent to regenerate a high-voltage polyanionic cathode material. This process ensures the complete recycling of all the elements in mixed cathodes and the deep eutectic solvent can be reused. The regenerated LiFe<sub>0.5</sub>Mn<sub>0.5</sub>PO<sub>4</sub> has an increased mean voltage (3.68 V versus Li/Li<sup>+</sup>) and energy density (559 Wh kg<sup>-1</sup>) compared with a commercial LiFePO<sub>4</sub> (3.38 V and 524 Wh kg<sup>-1</sup>). The proposed upcycling strategy can expand at a gram-grade scale and was also applicable for LiFe<sub>0.5</sub>Mn<sub>0.5</sub>PO<sub>4</sub> recovery, thus achieving a closed-loop recycling between the mixed spent cathodes and the next generation cathode materials. Techno-economic analysis shows that this strategy has potentially high environmental and economic benefits, while providing a sustainable approach for the value-added utilization of waste battery materials.