Fluoropolymer-Based Separator: Preparation Characterization and Performance in Battery Devices

Abstract

We utilized the fluoro-based polymer PVdF-co-HFP to prepare the separators for ion batteries by casting-film and electrospinning membrane In the part of casting-film we tried to mix the PVdF-co-HFP and ionic liquid with different ratios According to the SEM analysis it would be found that the addition of ionic liquid could increase the porous structure; on the other side we added the cross-linker 1 3-Diaminopropane(DAP) into the solution of polymer and then prepare the separators by the casting-film and electrospinning membrane We tested the physical properties of our separators by SEM、FT-IR、TGA、DSC analysis and the electrochemical properties by AC impedance analysis From the SEM analysis the electrospinning membrane of PVdF-co-HFP could helpfully increase the mobility since the porous structure It also could be observed the microphase separation after soaked in the ionic liquid According to the TGA、DSC analysis we found that after the addition of cross-linker the mechanical properties promote with the increasing of the ratio of cross-linker without obvious difference of thermal properties In the electrochemical property analysis the uptake of electrolyte decreased with the increasing of the ratio of cross-linker after the membrane soaked in the ionic liquid; in the AC impedance analysis it also shows the same tendency of the ionic conductivity It explained the influence of the cross-linker for the membrane structure but the ionic conductivities were still lower than the PVdF-co-HFP separators in lithium-ion batteries As for the compatibility of aluminum-ion battery there was a concern about the reactivity for the electrolyte which is wildly used in aluminum-ion battery It is inferred that if we would like to apply our PVdF-co-HFP electrospinning membrane to aluminum-ion batteries it is necessary to modify the surface structure of polymer in order to improve the compatibility of aluminum-ion battery

Date of Award	2019
Original language	English
Supervisor	Wen-Chung Wu (Supervisor)