Assessing Methods and Data for Pore-Size Distribution of PEMFC Gas-Diffusion Media

Data for hydrophilic and hydrophobic pore-size distributions are presented for two gas-diffusion media (GDM) commonly used in proton exchange membrane fuel cells (PEMFCs). The data were obtained using two measurement methods, intrusion porosimetry and the method of standard porosimetry (MSP). The use of multiple working fluids to access hydrophilic and hydrophobic pores is discussed as well as limitations associated with structural changes of the GDM during the tests. The differences in the data between the two methods are discussed for both the carbon-cloth and carbon-paper GDM and it is shown that these differences have significant implications relative to the distribution of hydrophilic and hydrophobic pores that control liquid-water transport. The analysis presented in this work shows that the MSP can lead to a more consistent interpretation of the GDM structure for materials that are compressible. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3080653] All rights reserved.