Designing deep eutectic solvents for upcycling spent Lithium-ion battery cathode

The industrialization of recycling the spent lithium-ion batteries present promising opportunities and challenges. We have designed several strategies for recycle or upcycle spent lithium-ion batteries to value-added materials. DESs composed of weak acidic and strong coordinated guanidine hydrochloride + lactic acid, hydroxylamine hydrochloride (NH₂OH·HCl) + ethylene glycol with acidity, reducibility, and coordination capability, and ternary DESs ChCl:MCl_x:Levulinic acid by synergistic effects were applied for the efficient leaching of cobalt and lithium ions from LiCoO₂ (LCO).

We further developed a strategy by combination of DES 3,4,5-trihydroxybenzoic acid + ChCl dissolution and a following solvent-induced crystallization for upcycling LCO to cobalt-polyphenol network.^[1] When organic building block, Cl^-, and inducing agents concurrently exist in the system, one-step conversion from LCO to MPNPs could be achieved.^[1]

Finally, we applied machine learning (ML) technique for accelerating the discovery of novel promising DESs systems for cathode leaching.^[2] Acidity, coordination, and reducibility were identified as the most important properties for the leaching efficiency and the importance of them were quantified by Shapley additive explanation (SHAP) method. A conditional Generative Adversarial Network (CGAN) model was established for rapidly identifying promising DESs and achieved excellent agreement with experimental results.

Reference

[1]. Z. Wang, Y. Chen, F. Zhou, R. Qin, Y. Tian, Z. Xue, T. Mu, Upcycling spent lithium-ion battery cathodes into cobalt-polyphenol networks by DES dissolution and solvent-induced crystallization, Green Chemistry 26, 5988-5996, 2024.

[2]. F. Zhou, D. Shi, W. Mu, S. Wang, Z. Wang, C. Wei, R. Li, T. Mu, Machine learning models accelerate deep eutectic solvents discovery for the recycling of Lithium-ion battery cathodes, Green Chemistry 26, 7857-7868, 2024.