Co-solvent controlled PVDF extraction from spent Li-ion batteries using supercritical CO2

Journal article, 2025

The recycling of polyvinylidene fluoride (PVDF) from spent lithium-ion battery black mass was investigated using supercritical carbon dioxide (SCCO2) combined with dimethyl sulfoxide (DMSO) as a co-solvent. Experiments were conducted at 70 °C and 80 bar for 15 min, varying the DMSO volume. Thermogravimetric analyses revealed that utilizing 4 mL of DMSO enabled the cumulative recovery of 55.6 wt% of PVDF. Thermogravimetric analysis confirmed a significant enhancement in PVDF extraction compared to atmospheric pressure (1 atm), where minimal PVDF was removed even after extended periods of solvent mixed black mass up to 18 days at room temperature and 24 h at 70 °C. Scanning electron microscopy revealed particle size reduction from approximately 93 µm to 43 µm and decreased agglomeration in treated samples, demonstrating improved particle homogeneity due to binder removal. Fourier-transform infrared spectroscopy and X-ray diffraction analyses confirmed that the chemical structure and crystalline phases of recovered PVDF remained intact. Despite its significance, PVDF recycling has not yet been established at an industrial scale. This study demonstrates the potential of the SCCO2–DMSO system as a rapid, sustainable, and scalable approach for the efficient recovery of PVDF from industrial lithium-ion battery waste.