A New Type of High Temperature Membrane for Proton Exchange Membrane Fuel Cells

The proton exchange membrane (PEM) fuel cell operated at high temperature is advantageous than the current low temperature PEM fuel cell, in that high temperature operation promotes electro-catalytic reaction, reduces the carbon monoxide poisoning, and possibly eliminates methanol crossover in Direct Methanol Fuel Cell (DMFC). However, current commercially viable membranes for PEMFC and DMFC, such as the de-facto standard membrane of Dupont Nafion membrane, only work well at temperatures lower than 80°C. When it is operated at temperatures of higher than 80°C, especially more than 100°C, the fuel cell performance degrades dramatically due to the dehydration. Therefore, high temperature proton exchange membrane material is now becoming a research and development focus in fuel cell industry. In this paper, a new type of high temperature PEM membrane material was investigated. This new type of membrane material was optimally selected from polyether ether ketone (PEEK)-based materials, poly (phthalazinon ether sulfone ketone) (PPESK). The performance of the sulfonated PPESK membrane with degree of sulfonation (DS) of 93% was studied and compared to that of Nafion (®Dupont) 117 membrane. The result showed SPPESK has a comparable performance to Nafion (®Dupont) 117 at low temperature (<80°C) and better performance at high temperature (>80°C). The other advantage of SPPESK is that it has much lower cost than that of Nafion. These characteristics make SPPESK an attractive candidate for high temperature proton exchange membrane material.