Alkaline exchange membranes (AEM) fuel cells are an attractive cost-saving alternative to traditional proton exchange membrane (PEM) fuel cells. In recent years, anion conducting polymer membranes have reached levels of ionic conductivity and chemical stability that rival that of Nafion, the current state of the art in PEM technology. However, these two important qualities have not been achieved before in the same AEM material until now. In this study, a series of tetrablock copolymers containing an all-hydrocarbon backbone and tethered quaternary ammonium groups were synthesized based on vinyl addition polymerization of norbornene. Several variations of block copolymer AEMs with different ion exchange capacities (IEC) were made by adjusting the ratio of hydrophilic to hydrophobic blocks. Correlations were found between the ionic conductivity and mechanical properties to the polymer structure, channel size, and degree of phase separation. Furthermore, it was found that light crosslinking of the membranes allows for high IEC materials to be used while maintaining acceptable water uptake. The crosslinked AEMs have demonstrated record-high hydroxide conductivities (198 mS/cm) for a chemically stable polymer. The chemical degradation at 80oC in 1 M KOH was &lt;1% degradation in 1,200 hours. The AEMs were also used to construct MEAs for alkaline fuel cells with peak power densities of over 700 mW/cm2.

Highly conductive, chemically stable, hydroxide conducting membranes based on poly(norbornene)

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.