(229f) Confined PFSA-Zeolite Proton Conducting Membrane: The Effects of Confinement and Zeolite-Type

Perfluorosulphonic
acid (PFSA) membranes are a well-known proton exchange membrane and the 'gold
standard' commercial Nafion membrane is renowned for its excellent proton
conductivity and long term stability under fully hydrated conditions. However,
their efficiency is highly dependent on the hydration level of the membrane, making
water management an important issue. Traditionally, these membranes use external
humidifying equipments to ensure optimum operation, which often translates to
an increase in costs and lower efficiency. Thus, the PFSA membranes are highly
sensitive to temperature, making operations at temperatures higher than 80^oC
difficult, although a higher temperature would increase the efficiency of the
electrocatalysts and improve its poison tolerance. A proton conducting membrane
that can operate effectively without humidifying aid and at higher temperature
operations is very attractive.

Recently
our lab reported a novel self-humidifying membrane that is obtained by
confining Nafion PFSA within zeolite-coated pores of a stainless steel foil that
displays superior performances compared to the commercial Nafion 117 membrane. A
multi-layered zeolite was deposited on the stainless steel; a nonporous
silicalite-1 zeolite layer served as an insulating and anti-corrosion coating,
a thin layer of nanozeolites (including LTA, BEA, FAU, and MFI) for water
retention and a surface layer of HZSM-5 zeolite as a protective layer. This
work investigates the effect of confinement on the physicochemical and
thermomechanical properties of PFSA. We also explore the effect of water
retention properties of various zeolites on the performance of the PEMFC.