Self-Cross-linking Nanocomposite Membranes for Green Recycling of the Solvent during Lithium-Ion Battery Manufacturing

Polyvinyl alcohol (PVA)/CNT composite membranes were prepared without adding cross-linkers; herein, carboxylated CNTs served as alternative cross-linkers. A molecular simulation confirmed the cross-linking capability between CNTs and PVA chains, which led to the prediction that the cross-linked PVA/CNT complex would be stable in water. To realize the simulated outcome, the multiwalled CNTs were activated and functionalized via sonication methods and subsequent acid treatment. The PVA/CNT composite membranes, including the CNTs treated by probe sonication, exhibited sufficient stability against dissolution in water at 80 °C when the CNT loading reached 1.5 wt %, thus substantiating the proposed idea. The composite membranes exhibited a high separation performance for green recycling of 1-methyl-2-pyrrolidone (NMP) during manufacturing of lithium-ion batteries (LIBs). Long-term operations using membranes with 1.5 wt % CNTs also exhibited a steady combination of total flux and water/NMP selectivity of approximately 0.06 kg/m²·h and 3500, respectively. Thus, the membranes developed here and the corresponding NMP dehydration performance could contribute to increasing the sustainability of the LIB manufacturing industry.