Perfluorosulphonic acid (PFSA) membranes are the 'gold standard' commercial Nafion membrane because of its excellent proton conductivity and long term stability under fully hydrated conditions. Their efficiency is highly dependent on the hydration level of the membrane, leading to a sharp decline in performance with a decrease in hydration or an overflow of water causing a flooding in the membrane and hindering the reactant diffusion. As such, water management system is a crucial component of proton exchange membrane fuel cell. As traditionally these membranes need external water regulating equipments and are unable to perform optimally at high temperatures, a membrane that can self humidify and can operate at a high temperature is heavily researched on. Recently our lab reported a novel self-humidifying membrane that requires no humidifying aid by confining Nafion within zeolite-coated microsized pores on a stainless steel support, displaying superior performances compared to the commercial Nafion 117 membrane. The novel membrane is fabricated by seeding and growing a thin silicalite-1 layer on a 50 �m-thick perforated stainless steel mesh before casting it with Nafion. The layer of zeolite serves as a water retention layer that enables the membrane to self-humidify. The MEA is then assembled by hot pressing the confined Nafion membrane between two gold-coated stainless steel plates with a thin layer of Pt/C brushed on. MEA performance was measured in a home-made test unit and the electrical performance was monitored by CHI 660C electrochemical station with CHI 680 Amp Booster. Tests were ran to investigate the relationship between material property and call performances. e.g. testing the water retention of various zeolites, leaching of Al ions. The effect of different types of zeolites are explored in this work to investigate the role of confinement and choice of zeolitic materials with different properties on the performance of the self-humidifying PEMFC. The zeolite types include MFI, FAU (NaX and NaY) and BEA. The varible zeolite layers are grown on top of the silicalite-1 layer via template-free method before the confinement of the Nafion.

Effects of zeolite types and their different properties on proton exchange membrane

247th National Meeting (2014)

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