Estimation of kinetic and electric parameters of liquid feed passive DMFCs

Abstract

The study of polarization curves is an important part for evaluating the performance of passive direct methanol fuel cells (DMFCs). This study must be essentially followed by other experiments to gain knowledge of important kinetic and electrical parameters such as exchange current density, charge transfer coefficients, ohmic resistance, etc. This experimentation include in-situ characterization techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current interrupt (CI) technique which are expensive to carry out. Hence, this study develops a semi-analytical model for estimating exchange current density, charge transfer coefficients and ohmic resistance directly from the polarization curves. In addition, a simple “3/4-Point method” is introduced, utilizes the polarization curves for the estimation of kinetic and electric parameters. The triad (proposed model, 3/4-Point method and polarization/EIS experiment) are compared and exhibited similar trends, thereby validating it as a tool for estimation of a large class of parameters. The model is comprehensive as it is valid throughout the polarization curves, thereby avoiding the need for multiple strategies in different regions of the polarization curves to calculate various parameters. The model can serve to know the values of these parameters by-hand before other experimentations which involves high cost and sophisticated experimental conditions.