Electrospun Fluorinated Polyimide/Polyvinylidene Fluoride Composite Membranes with High Thermal Stability for Lithium Ion Battery Separator

The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries (LIBs). Therefore, it is crucial to develop novel nanofibrous membranes with enhanced mechanical strength and thermal stability. In this work, the fluorinated polyimide (FPI) was synthesized and blended with polyvinylidene fluoride (PVDF) to fabricate composite nanofibrous membranes (CNMs) via electrospinning method. Benefiting from the introduction of aromatic FPI, the prepared PVDF/FPI nanofibrous membranes were endowed with enhanced mechanical strength and thermal stability. When the FPI content increased from 0 to 30 wt%, the tensile strength of composite nanofibrous membranes enhanced from 1.57 to 2.30 MPa. Moreover, there are almost no dimensional shrinkage for the CNM-30 containing 30 wt% FPI after heat treatment at 160 degrees C for 1 h. Furthermore, the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes. The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms center dot cm(-1), respectively. The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.

Automated summary

In this study, composite nanofibrous membranes (CNMs) with enhanced mechanical strength and thermal stability were successfully fabricated by synthesizing fluorinated polyimide (FPI) and blending it with polyvinylidene fluoride (PVDF). The CNMs showed improved tensile strength and almost no dimensional shrinkage after heat treatment. In addition, the CNMs exhibited enhanced electrochemical performances compared to neat PVDF and commercial Celgard membranes, with higher electrolyte uptake and ionic conductivity. The prepared CNMs offer a promising approach for high-performance separator design.