Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-V-1INFLUENCE OF ICE ON MEAs OF PEM-FCsG. Gavello, E.P. Ambrosio, U.A. Icardi, S. Specchia, N. Penazzi, V. Specchia, G. SaraccoDepartment of Materials Science and Chemical Engineering - Politecnico di TorinoCorso Duca degli Abruzzi 24, 10129 Torino, Italye-mail: stefania.specchia@polito.it – fax: +390115644699PEM-FCs are being recognised to be as one of the best candidates as pollution-free andenergy-saving power sources for electric or hybrid vehicles because of their high energyconversion efficiency (~50%) and zero or nearly zero emissions. At present, significantintroduction of PEM-FCs is limited by their cost, their behaviour in sub-freezing conditions,the unavailability of an H 2 distribution infrastructure and the rather low amounts of H 2 gasthat can be safely stored on board vehicles. The start-up and stationary behaviour of PEM-FCs below 0°C is one of the most challenging tasks to be solved before commercialisation:freezing of water inside the PEM-FC could form ice layers in the electrodes and in the gasdiffusion layer (GDL). Therefore the cell reaction is limited or even inhibited. The automotiveindustry started to develop solutions to reduce the start-up time of FC systems: the strategiesvaried from H 2 catalytic combustion on the electrode catalyst to fuel starvation or externalstack heating to increase the stack temperature [1].This study investigates the phenomena of water freezing below the freezing point inPEM-FCs. In particular, the analysis was focused on the effects of ice into the MEA, asmechanical stress, and the decay of the polarization curve. Such an effect was investigated ona single cell PEM-FC using a 5 cm 2 MEA from Electrochem (Nafion membrane, catalysedwith 20% wt Pt 1.0 mg·cm –2 supported on Vulcan XC-72R Carbon Black) with carbon paperas GDL. The MEAs, in both hydrated and de-hydrated status, were conditioned for 48 h at-10°C by placingthem into athermostaticchamber(Angelantoni UC600-70 model), toassure the completeice formation withinthe various MEAlayers. After reconditioningatFig. 1: polarization curves of the various MEAs.458