Methanol Fuel Cell Model: Anode

Abstract

An isothermal, steady‐state model of an anode in a direct methanol feed, polymer electrolyte fuel cell is presented. The anode is considered to be a porous electrode consisting of an electronically conducting catalyst structure that is thinly coated with an ion‐selective polymer electrolyte. The pores are filled with a feed solution of 2 M methanol in water. Four species are transported in the anode: water, methanol, hydrogen ions, and carbon dioxide. All four species are allowed to transport in the x‐direction through the depth of the electrode. Species movement in the pseudo y‐direction is taken into account for water, methanol, and carbon dioxide by use of an effective mass‐transfer coefficient. Butler‐Volmer kinetics are observed for the methanol oxidation reaction. Predictions of the model have been fitted with kinetic parameters from experimental data, and a sensitivity analysis was performed to identify critical parameters affecting the anode's performance. Kinetic limitations are a dominant factor in the performance of the system. At higher currents, the polymer electrolyte's conductivity and the anode's thickness were also found to be important parameters to the prediction of a polymer electrolyte membrane fuel cell anode's behavior in the methanol oxidation region 0.5–0.6 V vs. a reversible hydrogen electrode. © 1999 The Electrochemical Society. All rights reserved.