Methanol fuel cell model: Anode

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. (C) 1999 The Electrochemical Society. S0013-4651(97)12-114-0. All rights reserved.