Proton-Conducting Membranes for Fuel Cells

Kurzfassung

A lot of research has been carried out in past decade to develop membranes for the whole spectrum of applications, namely automotive, stationary, and portable applications. PFSA-based membranes have played the most prominent role until now. Much research has been conducted into the details of Proton transport through different polymers and into methods of improving their properties, but a viable and inexpensive Substitute to Nafion has yet to be developed. On the other hand, different approaches using PTFE fibril reinforcements have been successfully applied to PFSA-based membranes to make them more mechanically and thermally stable and thus to enhance durability. Such membranes are also reported to have better humidity and heat management characteristics besides lower specific protonic resistance and high power densities. Alternative approaches to modify the properties of PFSA-based membranes by impregnating inorganic fillers have also been reported to prodlice favorable results. But such membranes still await wide adoption. For liquid-phase operation (as in DMFCs), very inexpensive membranes based on nanoporous inorganic Support matrices filled with liquid electrolytes have also shown good potential. PFSA-based membranes cannot be used in the high-temperature range. A good alternative for the high-temperature range critical to automotive applications is the inorganic, acid-doped PBI-based membrane from Celanese AG. In spite of all these improvements, a lot of work is still needed to improve various membrane characteristics which would make designing fuel cell-based systems much simpler and would eliminate the need for several BOP components, which adds to the complexity of the fuel cell systems.