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

Yuan Xu,Jun-Bo Fang,Yun-Ze Long,Miao Yu,Jian-Wei Zhu,Xiao Li

doi:10.1155/2020/3879040

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.

Highlights

With the continuous advancement of information, materials, and energy technologies, lithium-ion batteries have become a hotspot in the research and application of new power supply technologies in recent years due to their long cycle life, high energy density, and fast charge and discharge rates [1, 2]
It is of great significance to study separators with high temperature resistance and strong thermal stability for greatly improving the operating temperature range and safety of lithium-ion batteries
It can be seen from the figure that the average diameter of SiO2 nanofibers is smaller than PVDF-HFP; PVDF-HFP fibers are relatively straighter

Summary

Introduction

With the continuous advancement of information, materials, and energy technologies, lithium-ion batteries have become a hotspot in the research and application of new power supply technologies in recent years due to their long cycle life, high energy density, and fast charge and discharge rates [1, 2]. It is of great significance to study separators with high temperature resistance and strong thermal stability for greatly improving the operating temperature range and safety of lithium-ion batteries. We had successfully fabricated flexible inorganic SiO2 battery separators via electrospinning [18] It has excellent heat resistance; the low mechanical strength of the pure SiO2 membrane limits its practical application. We prepared a SiO2/PVDF-HFP composite porous fiber membrane (SPF) via electrospinning and rolling bonding and applied it to the battery separator. Such a composite separator was expected to have excellent mechanical stability and a function of heat-closed pores in addition to excellent thermal stability

Experimental

Results and Discussion

Conclusions