Electrospun High-Thermal-Resistant Inorganic Composite Nonwoven as Lithium-Ion Battery Separator

Abstract

Separators are key materials to ensure the safety of lithium-ion batteries and improve their performance. Currently, commercial lithium-ion battery separators are mainly polyolefin organic diaphragms, but their temperature instability leads to battery short circuit and fire risk. A flexible SiO2 nanofiber membrane combined with a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) nanofiber membrane is prepared by an electrospinning method. The mechanical strength of the SiO2/PVDF-HFP composite nanofiber membrane (SPF) is twice as high as the pure SiO2 nanofiber membrane and at 200°C, there are almost no dimensional changes of the SPF separators. Compared to commercial polyethylene (PE) separators, SPF shows excellent thermal stability and large-area closed cells at 180°C when used in lithium-ion battery separators. The porosity of SPF is 89.7%, which is more than twice than that of an ordinary PE separator. The liquid absorption rate of SPF is much higher than an ordinary PE separator and has reached 483%. Furthermore, the cycle and rate performance of lithium-ion batteries prepared by SPF has been improved significantly. These excellent properties, as well as the potential for large-scale production of electrospinning technology, make SPF an ideal choice for high-power battery separators.