Electrospun PVDF-HFP/PAN bicomponent nanofibers as separators in lithium-ion batteries with high thermal stability and electrolyte wettability

Abstract

Battery reliability is emerging as a new challenge due to the thermal stability and electrolyte wettability of polyolefin separators used in lithium-ion batteries. In this study, a method to improve the thermal stability and electrolyte wettability of a polyolefin separator is proposed. Bicomponent nanofibers were successfully fabricated by electro-spinning poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with high ionic conductivity and polyacrylonitrile (PAN) with excellent thermal stability. The nanofiber-based separator of PVDF-HFP/PAN exhibited high porosity (60–76%), electrolyte uptake (≅2,000%), and thermal stability (5%<shrinkage, at 200 °C) than conventional polyolefin separator. The battery using the bicomponent nanofiber separator composed of PVDF-HFP and PAN showed better cycle performance (421 mAh/g, after 80 cycle), efficiency (≅99.6%), and c-rate performance (418 mAh/g, 3C) than the battery using polyolefin separator.