The Effects of Sic Nanofillers on the Physical and Mechanical Properties of Pbi Membranes

Fuel cells are electrochemical devices that combine oxygen and hydrogen to obtain electricity and heat and water as by products. The central component of a fuel cell is the membrane electrode assembly, composed of an anode, cathode and a proton exchange membrane or polymer electrolyte. The electrolyte used during the experiment was phosphoric phosphoric acid-doped poly[2,2'-(p-phenylene)-5,5'-dibenzimidazole] (polybenzimidazole, (p-PBI)), an alternative to the commonly used water containing perfluorosulfonic acid-based membranes. Protons are conducted through the PBI membrane while the electrons are forced to travel through an external circuit to create electrical work. PBI based fuel cells operate at high temperatures, usually around 180^°C which may cause a small loss of phosphoric acid from the membrane, changing its physical and mechanical properties. In this study, PBI membranes that contained silicon carbide (SiC) nanofillers were synthesized to provide additional mechanical stability to the membranes. It was found that 5% SiC membranes were more stable than 1%, 3% and 7% SiC membranes, having a modulus of elasticity seven times superior. Additionally, the 5% membrane met the expected conductivity standards, with a value around 0.145 S/cm in a temperature range of 22^°C-160^°C.