Crystal structures of electrospun PVDF membranes and its separator application for rechargeable lithium metal cells

An electrospinning method was used to prepare electrospun PVDF-based membranes (EPMs) for battery separators applications. The morphology of the EPMs was investigated by scanning electron microscopy (SEM). The relations between applied voltage and average fiber diameter (AFD) under certain electrospinning conditions were discussed. The thermal properties and crystal structure of the EPMs also were investigated by differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD). Due to soften PVDF fibers in high temperature, the thermal treated EPMs can form an interconnected web structure, which greatly improves physical properties. Compared with Celgard™ 2400 (PP separator), the cell with EPM shows better cycling ability of CV and charge–discharge performance with little capacity loss after 50 cycles at C/2 rate.