Novel PVA-Based Porous Separators Prepared via Freeze-Drying for Enhancing Performance of Lithium-Ion Batteries

To address the challenges encountered by conventional polyolefin separators for lithium-ion batteries (LIBs), a porous poly(vinyl alcohol) (PVA) separator with a tailored structure was developed in this work. In the preparation, submicron spindle-shaped CaCO 3 acted as an excellent pore-forming agent, followed by freeze-drying to create dehydrated poly(vinyl alcohol) (d-PVA) as a novel porous separator to endow LIBs with better performance, safety in particular. The resulting d-PVA porous separator possessed high thermal dimensional stability (above 180 °C), tensile strength (42.3 MPa), mechanical flexibility, high porosity (65.4%), and admirable electrolyte wettability. Moreover, the separators showed higher ionic conductivity (1.27 mS cm –1 ) than the polypropylene (PP) separator (0.4 mS cm –1 ). Consequently, the LiFePO4/Li half-cell with a d-PVA porous separator demonstrated better cycling performance than the PP separator, even at a high rate. Undoubtedly, the as-prepared d-PVA porous separator has great potential in improving performance and safety of LIBs.