The membranes in direct methanol fuel cells must both conduct protons and serve as a barrier for methanol. Nafion, the most common fuel cell membrane, is an excellent conductor but a poor barrier. Polyvinyl alcohol pervaporation membranes are good methanol barriers but poor conductors. These and most other pervaporation membranes offer no significant advantages over Nafion in methanol fuel cell applications. However, polybenzimidazole membranes have demonstrated characteristics that suggest up to a 15-fold improvement in direct methanol fuel cells. This improvement may be due to an alternate form of proton conduction in which protons travel via a Grotthus or 'hopping' mechanism.
Bibliographical noteFunding Information:
This work was primarily supported by the Department of Defense, grant DAAH04-95-0094. Other support came from the National Science Foundation, grants CTS95-28755 and CTS96-27361.
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
- Barrier membranes
- Fuel cells
- Solubility and partioning