Preparation, microstructure, and electrochemistry of microporous polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene)

• Main Authors: Yung-Hao Chen, 陳永豪
• Other Authors: Tzu-Chien Hsu
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/62748471417769874139

碩士 === 國立中山大學 === 材料科學研究所 === 91 === Abstract In this study, we discuss the properties of gel polymer electrolytes based on poly( vinylidene fluoride-co-hexafluoropropylene ) (PVdF-HFP) with different preparing methods. Thermal properties by TGA and DSC, microstructure by XRD, pore size and porosity of the films by SEM, and electrochemistry by impedance analyzer and charging/discharging systems were investigated. From the TGA results, the addition of plasticizer or silica makes the decomposition temperature (Td) lowering about 2-6oC. At the same time, in DSC results, it lowers the melting temperature (Tm) about 16-20oC and crystallinity (ΔH) about 2-3 J/g. Changing the solvent or non-solvent does not affect Tm and ΔH much. In X-ray results, the addition of plasticizer or silica shows peak-broadening effect. After the films absorbing electrolytic solution, the peak-broadening effect is obvious. The solvent or non-solvent effects are more obvious due to the presence of the electrolytic solution. In SEM and conductivity results, the addition and extraction of the plasticizer helps to the pore formation, but the influence is limited. The effect is strengthened as the silica adds. The existence of plasticizer helps to increase the conductivity. It has one or two order of magnitude higher than other films, exceeding 10-3 S/cm. The silica helps the film to absorb electrolytic solution over 100 wt% and increases the conductivity to exceed 10-3 S/cm in the presence of plasticizer. In non-solvent effect, the films using propanol or octanol as a non-solvent have higher pore size and porosity. At the same time, they absorb electrolytic solution over 100 wt% and have the conductivity about 10-3 S/cm. The films using cyclohexane as a non-solvent have the smallest pore size, porosity, and conductivity. In solvent effect, the films using MEK as a solvent have the smallest porosity and conductivity. The films using acetone as a solvent have higher porosity and conductivity because of its low boiling temperature.