Proton-Exchange Membranes from Sulfonated Polyphosphazene Blends
Abstract
Proton-exchange membranes for direct methanol fuel cells were prepared from sulfonated polyBIS(3-METHYLPHENOXY)PHOSPHAZENE, which was blended with either Kynar (TM) Flex, polyacrylonitrite, or polybenzimidazole. In some cases the blended films were UV-crosslinked. The proton conductivity of the membranes was sufficiently high for fuel cell applications. The water swelling of the membranes was generally greater than that of Nafion 117, but the methanol crossover was lower than that of Nafion 117. Direct liquid methanol fuel cell tests were performed with MEAs fabricated with UV-crosslinked membranes containing sulfonated polyBIS(3-METHYLPHENOXY)PHOSPHAZENE and polyacrylonitrile (crosslinking was carried out using benzophenone as the photo-initiator). MEAs worked best when a high ion-exchange capacity (high conductivity) polyphosphazene membrane contacted the electrodes in which case the fuel cell power output was nearly the same as that with Nafion 117 (for current densities 0.15 A/sq cm), but the methanol crossover was 3-4-times lower than Nafion. With a three-membrane composite MEA (a lower conductivity methanol-blocking film sandwiched between two high conductivity membranes) there was a significant decrease in crossover (almost ten-times lower than Nafion 117) with a modest decrease in the fuel cell's current-voltage behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 04, 2003
- Accession Number
- ADA414518
Entities
People
- H. D. Yoo
- Jung‐Hee Lee
- Peter N. Pintauro
- Roy Carter
- Ryszard Wycisk
Organizations
- Tulane University of Louisiana