Innovative composite polymer electrolyte membrane for high-temperature PEM fuel cells
摘要
This research article focuses on the development of a poly-aramid (kevlar) and poly-propylene glycol (PPG) based composite polymer electrolyte membrane for use in high-temperature polymer electrolyte membrane fuel cells. Kevlar is a material well known for its high chemical, mechanical, and thermal stability, and PPG is used for ionic conduction in polymer electrolyte membranes (PEMs) for lithium-ion batteries, these properties of both materials are utilized to develop a composite membrane which possesses excellent thermal and mechanical stability, with the provision of reasonable ionic conductivity at high temperatures. Kevlar nano-fiber gel is prepared from industrial kevlar thread using sol-gel synthesis. By using dip coating in a layer-by-layer (LBL) assembly manner, 100 layers of kevlar and PPG were coated over each other to prepare a PEM that is flexible, has a thickness of 30 μm with very low surface porosity of around 8%, low surface roughness with a Ra value of 3.58%, and good wettability with a contact angle of 50°. The developed PEM is thermally stable up to 330 °C temperature and possesses exceptional tensile strength of 9.6 MPa with just 30 μm thickness. The developed PEM possesses ionic conductivity of 0.255 mS.cm− 1 at 90 °C and 0.182 mS.cm− 1 at 150 °C. FTIR/XRD indicate a hydrogen-bond–assisted proton-hopping mechanism; despite prioritizing thermal/mechanical robustness (stable to ~ 330 °C; 9.6 MPa at 30 μm), the dry, dopant-free membrane maintains 0.182 mS·cm⁻¹ at 150 °C.