An Impedance Study on the sPEEK/ZrO2 Membranes for Direct Methanol Fuel Cell Applications
Electrochemical impedance experiments were carried out in order to study the influence of the ZrO2 inorganic incorporation on the proton conductivity of sulfonated poly(ether ether ketone) (sPEEK) membranes. The impedance data was fitted to an extension of Randles’ circuit, within the inorganic content and temperature ranges considered. The model fits quite well for ZrO2 loads up to 10 wt.%. Such a model allows for characterizing the diffusion phenomena (Warburg) of the membrane electrode assembly (MEA), membrane and electrodes resistances, capacitive and inductive behavior. Proton conductivity was obtained from the impedance spectra and it was observed that it increases with temperature and decreases with the inorganic content. As a general trend, the Warburg parameter decreases slightly with the temperature, except for the 5 wt. % ZrO2 membrane that suffers a more pronounced influence. The Warburg parameter also decreases with the ZrO2 content.
António Torres Marques, António Fernando Silva, António Paulo Monteiro Baptista, Carlos Sá, Fernando Jorge Lino Alves, Luís Filipe Malheiros and Manuel Vieira
V.B. Silva et al., "An Impedance Study on the sPEEK/ZrO2 Membranes for Direct Methanol Fuel Cell Applications", Materials Science Forum, Vols. 587-588, pp. 926-930, 2008