Niccolo V. Aieta

The Effect of Heteropoly Acids on Stability of PFSA PEMs under Fuel Cell Operation

Membranes were cast from mixtures of the 3M perfluorinated sulfonic acid ionomer [side chain -O-(CF 2 ) 4 -SO 3 H] and various heteropoly acids (HPAs) at a 10 or 20 wt % doping level. Membrane electrode assemblies (MEAs) fabricated from these membranes were subjected to a fuel cell testing protocol from 70 to 100°C under relatively dry conditions, dew point of 70°C, to avoid leaching of the HPA. The most significant finding was that the more stable HPAs, H 4 SiW 12 O 40 , α-H 3 P 2 W 18 O 62 , and H 6 P 2 W 21 O 71 , reduce the rate of F - by over half and improve the power of the MEA by 9% under these conditions.

Tracking Crystallinity Changes in PFSA Polymers During Ex-Situ Peroxide Degradation

X-ray scattering is used to determine levels of crystallinity in both 3M® ionomer and Nafion®, both perfluorosulfonic acid (PFSA) based polymers. Weight loss and measured fluoride ion release both suggest breakdown of the polymer. X-ray scattering as well as mechanical measurements suggest that the crystalline domain size and spacing are unaffected by this degradation.