Influence of Catalyst Layer Binder on Catalyst Utilization and Performance of Fuel Cell with Polybenzimidazole-H3PO4 Membrane

This article reports on the impact of the catalyst layer (CL) binder on the performance of fuel cell (FC) with H3PO4-doped polybenzimidazole membrane. Nafion and fluorinated ethylenepropylene (FEP) were used as binders for carbon-supported platinum catalyst. FC performance declined with the increase of binder concentration in CL. Nafion binder was found to be more detrimental to FC performance than FEP. Changes of platinum electrochemically active surface area (ESA) in the cathode were evaluated by monitoring ESA of carbon support. ESA of carbon in the CL was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Carbon support ESA was found unaffected by the increase of binder (Nafion or FEP) to carbon support (C) mass ratio up to Nafion/C = 1 or FEP/C = 0.8. The difference in the influence of these binders on FC performance was ascribed to the difference in arrangement of particles of these binders within the CL. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3098499] All rights reserved.