Thermodynamic Properties of Direct Methanol Polymer Electrolyte Fuel Cell

Abstract

We established a new thermodynamic framework to predict the cell voltage of DMFC using open-circuit-voltage (OCV) and overpotential. In the absence of applied current, the overpotential due to the ohmic drop and the electrode overpotential do not exist. The corresponding corrections by thermodynamic relationship, therefore, we calculate the OCV of DMFC. In addition, the model of methanol crossover processes is presented which is used to predict the effective methanol concentration at the catalyst surface and thereby the anode polarization. The simple thermodynamic model is presented to estimate easily the influence of the methanol crossover on the open-circuit-voltage of a methanol fuel cell. The model has been checked in a DMFC using Nafion membranes as electrolyte. The OCV and methanol crossover overpotential of several commercial perfluorosulfonic membranes are calculated by the proposed model, and then compared with experimental data for the corresponding systems.