Analysis of Reaction Rates in the Cathode Electrode of Polymer Electrolyte Fuel Cell I. Single-Layer Electrodes

This paper explores transport and electrochemical phenomena in the cathode electrode of polymer electrolyte fuel cells and presents a theoretical study on the spatial distribution of reaction rates across the electrode. Profiles of the electrolyte-phase potential and local electrochemical reaction rate are explicitly obtained and related to a variable , which lumps the impacts of a number of parameters including composite properties, electrode structure, and other factors such as oxygen concentration and water content. Spatial variations of the local reaction current are analyzed and impacts of the parameters are investigated. Finally, a variable, the reaction rate nonuniformity ℏ, is defined based on average current density and is found to vary linearly with another lumped parameter , which combines the effects of average current density and ionic conductivity. It is also found ℏ can be used to approximate the current density contribution of each portion of the electrode if the electrode is divided by half.