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

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 degrees 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 degrees 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.