PVDF-HFP Fibers separator with superior β-phase content for enhanced cycling stability in Lithium metal batteries

Electrospun poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) fibrous separators with controlled crystalline orientation were successfully developed for lithium metal batteries (LMBs). The electrospun separator exhibits a well-aligned fibrous network and predominant β-phase crystallization, demonstrating significantly enhanced ionic conductivity (0.63 mS cm −1 ) and superior electrolyte wettability compared to conventional NIPS-derived separators. The unique architecture enables homogeneous lithium deposition and extends cycling stability to 700 h in Li||Li cells, while maintaining excellent rate capability with 136.3 mAh g −1 at 2C in L cells. This work provides valuable insights into designing advanced polymer separators through microstructure and crystalline phase control for high-performance energy storage applications.