Lithium-ion battery separators based on electrospun PVDF: A review

Separator is an essential component in lithium-ion batteries (LIBs), which greatly affects the electrochemical performance of the battery. Poor electrochemical performances of commercial lithium-ion battery separators limit their use in electric vehicles and energy storage systems. The poor electrochemical performance arises from the low porosity, high thermal shrinkage, and poor thermal stability of poly olefin-based separators. This issue can be resolved by the use different types of polymer separators and also by the use of different separator fabrication technologies. Electrospinning technology gained much attention in recent years, which helps to design new separator materials with high porosity, surface area, electrolyte uptake, and ionic conductivity. Among the various polymeric separators, polyvinylidene fluoride (PVDF) and its copolymers are extensively used as LIB separators due to their attractive properties like good mechanical strength, thermal stability, non-reactive nature, easy processability, etc. Considering the relevance of PVDF based polymers and electrospinning technology, the present review highlights the impact of different PVDF based electrospun separators on battery performance, different materials and methods used to enhance the electrochemical performance and recent developments are detailed in this review. Insight from this review, the interplay of PVDF based electrospun separators (single polymer, polymer blends, and nanocomposites), porosity, blend component, nanofiller - battery performance indicate that in future PVDF based separator will be designed to play a major role in LIBs.