Electrospun PVDF/SiO ₂ Separators for High‐Performance Lithium‐Ion Batteries

The performance and safety of lithium‐ion batteries (LIBs) are strongly influenced by the properties of the separator, which must simultaneously ensure efficient ion transport, high electrolyte affinity, electrochemical stability, and adequate mechanical integrity. However, achieving a balanced combination of these properties remains challenging, particularly for polymer‐based separators. In this work, electrospun PVDF/SiO 2 nanofibrous membranes were fabricated and systematically evaluated as LIB separators, with specific attention to the effect of SiO 2 content on the structural and electrochemical characteristics. Among the prepared samples, the PVDF separator containing 10 wt% SiO 2 exhibited the most favorable balance of properties. This membrane features a uniform nanofibrous morphology with an average fiber diameter of ~310 nm, a high porosity of 66%, and an exceptional electrolyte uptake (EU) of 375%, which collectively promote efficient electrolyte retention and ion transport. Consequently, a high ionic conductivity of 1.99 mS cm −1 was achieved while maintaining acceptable mechanical properties, including a tensile strength of 1.36 MPa and an elongation at break of 39%. Linear sweep voltammetry (LSV) measurements revealed an extended electrochemical stability window up to ~5.0 V, indicating enhanced oxidation resistance. When employed in Li/LiFePO 4 half‐cells, the optimized separator delivered stable long‐term cycling performance, retaining a discharge capacity of about 100 mAh g −1 after 250 cycles with ~80% capacity retention and a Coulombic efficiency close to 100%. In addition, the cell assembled with the PVDF + 10 wt% SiO 2 separator exhibited better rate capability, delivering a discharge capacity of about 77 mAh g −1 at 2 C and maintaining about 103 mAh g −1 after 100 cycles at 1C. The results demonstrate that rational incorporation of SiO 2 nanoparticles into electrospun PVDF separators can effectively balance porosity, electrolyte wettability, ionic conductivity, and electrochemical stability, offering a simple and practical strategy for developing high‐performance separators for advanced LIBs.