Abstract:
High Temperature Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) technology is a successor of LT-PEMFC technology, which addresses many limitations of the previous technology. By using this technology we can reduce the overall cost of fuel cell and can improve performance of fuel cell, but it requires a PEM that can withstand high temperatures with the provision of reasonable ionic conductivity. This research thesis is about an ultra-thin composite HT-PEM of Poly-Aramid (Kevlar) and Poly-Propylene Glycol (PPG) developed using dip coating in Layer by Layer (LBL) assembly. Kevlar is a material well known for its exceptional properties; high chemical, mechanical and thermal stability. These properties of Kevlar are utilized in this research work to develop a thermally and mechanically stable PEM. Kevlar fiber gel is prepared from industrial Kevlar thread using Sol-Gel synthesis which is a low cost and easy method of Kevlar fiber synthesis. Dip coating in LBL assembly manner is then used to coat 100 layers of Kevlar and PPG over each other to prepare a thermally and mechanically stable PEM that is transparent, flexible and also possesses reasonable ionic conductivity at temperatures above 100°C. The developed PEM has a thickness of 30μm with very low porosity, low roughness and good wettability. The developed PEM is thermally stable up to 330°C temperature and possesses exceptional tensile strength of 9.6 MPa with just 30μm of thickness. The developed PEM also possesses ionic conductivity of 0.219 mScm−1 at 120°C. All of these properties make this PEM a good candidate for high temperature fuel cell operations.
