Effect of Pore Size Distribution on Cathode Performance of Membrane-Electrode Assembly with a Hydrocarbon-Based Binder

Abstract

The relationship between pore size distribution and cathode performance was investigated for membrane-electrode-assemblies (MEAs) with a hydrocarbon-based (HC) binder and a poly (perfluorosulfonic acids) (PFSA) binder. The MEA with an HC binder exhibited a higher gas diffusion resistance than that with the PFSA binder. The pore size distribution measurement revealed that the HC binder was likely to cover a larger area of the carbon support surface compared with a PFSA binder, and that a large amount of the HC binder easily penetrated the primary pores inside Pt/C agglomerates, which decreased the volume of the pores. Conceivably, the HC binder in primary pores blocked the oxygen diffusion to the cathode catalyst. Based on the above consideration, we focused on increasing the primary pore volume. Consequently, the volume was doubled, and therefore, the gas diffusion resistance at 0.25 A cm-2 was successfully reduced from 1600 to 410 mΩ cm2.