Electrospun SiO₂- Containing Poly(Vinylidene Fluoride) Nanofiber Membranes as Lithium-Ion Battery Separators: Effect of SiO₂ Content on Performance

Abstract

A separator is one of the main components of lithium-ion batteries. It separates the cathode and anode while allowing the exchange of ions, and reduces the risk of a short circuit that can cause battery failure. In this study, membranes consisting of electrospun, SiO2-containing, poly(vinylidene fluoride) nanofibers were synthesized for use as separators in lithium-ion batteries. Moreover, this study investigated the effect of the volume of colloidal SiO2 (1, 2, and 3 mL) in the precursor (a PVDF/SiO2 solution containing 10 mL of PVDF solution) on the properties of an associated nanofiber membrane and its performance in a coin cell battery. It was found that the porosity, mechanical strength, and thermal resistance of PVDF/SiO2 nanofiber membranes increase with the increasing volume of colloidal SiO2 in the precursor. The PVDF/SiO2 precursor containing 3 mL SiO2 produces an optimal membrane separator with a porosity of 67%, thermal shrinkage ratio of 1.3%, and elongation at break of 24%. These results show that PVDF/SiO2 separators have higher porosity rates than pp and PE membrane separators. Furthermore, the corresponding coin cell battery achieves the highest charge and discharge capacities, i.e., 2.36 and 1.36 mAh/g, respectively.