Ionic conductivity and electrochemical properties of polymer gel electrolyte using novel three-dimensional network polymer host composed of electrospun nanofibers

The objective of this project is to prepare a novel three-dimensional polymer gel electrolyte and evaluate its ionic conductivity and electrochemical properties. The polymer gel electrolyte is based on varying composition of polyethylene oxide in the polymer blend of polyvinylidene fluoride (PVDF) and polyethylene oxide (PEO). Morphology of the electrospun membranes was examined by field emission scanning electron microscopy (FESEM) which revealed a three-dimensional network of interlaid and straight fibers with bead-free morphology. Thermal characterization was performed through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies. Porosity, electrolyte uptake and electrolyte leakage were also evaluated. PVdF-PEO 80/20 after washed electrospun membrane was found to load the highest amount of lithium salt with an electrolyte uptake of 832wt%. The voids and cavities created by the interlaying fibers effectively aid in the preparation of polymer gel electrolyte by loading with lithium bis(trifluoromethysulfony)imide (LiTFSI) dissolved in ethylene carbonate (EC)/diethyl carbonate (DEC). Ionic conductivity of 6.31mS/cm was recorded to be the highest, exhibited by the polymer gel electrolyte based on PVdF-PEO 80/20 after washed membrane. The polymer gel electrolyte also exhibited stable cycle performance and good charge-discharge property under the test conditions. The results demonstrated that PVdF-PEO electrospun membranes have complementary advantageous characteristics of PVDF and PEO, which show that the polymer blend electrolytes are promising materials for lithium ion batteries.Bachelor of Engineering (Materials Engineering