Preparation of High Performance Lithium‐Ion Battery Separators by Double‐Needle Electrospinning

Abstract Traditional polyolefin separators suffer from poor heat resistance and wettability with electrolyte, which leads to compromised safety and electrical properties of lithium‐ion batteries. Polyvinylidene fluoride (PVDF) has high thermal stability and good chemical stability, but its high crystallinity leads to low ionic conductivity. In order to solve these problems, polyvinyl alcohol (PVA) resin was introduced in this paper, and the PVDF/PVA composite separator was prepared by double‐needle electrospinning. The introduction of PVA resin improved its mechanical properties and electrolyte wettability, and ionic conductivity after assembly into a battery. Double‐needle electrospinning process is simple and can preserve the surface properties of fibers, and the prepared composite separator had a high porosity and electrolyte uptake. The composite separator has an ionic conductivity of 2.454 mS ⋅ cm −1 , a high capacity retention rate of 97.5 % after 100 charge and discharge cycles, and a capacity retention rate of 86.8 % under 2 C high‐rate discharge. The results show that the battery assembled with PVDF/PVA composite separator has high safety performance and electrical performance, and has application prospects.