Experimental evaluation and mathematical modeling of a direct alkaline fuel cell

The performance of a direct alkaline fuel cell (AFC) is studied separately using methanol, ethanol and sodium borohydride as fuel. Potassium hydroxide solution was used as an electrolyte. Pt-black and manganese dioxide catalyst were used to prepare the anode and cathode electrodes. Ni mesh was used as current collector. The direct alkaline fuel cell was constructed with the prepared anode and cathode electrodes and Ni mesh. The current density-cell voltage characteristics of the fuel cell were determined by varying load and at different experimental conditions, e.g., electrolyte concentration, fuel concentration and temperature. The fuel cell performance increases initially with the increase in electrolyte (KOH) concentration and then decreases with further increase of the same. The cell performance increases initially and then no appreciable improvement noticed with the increase in fuel concentration. The performance of the fuel cell increases with increase in temperature in general with the exception to NaBH4 alkaline fuel cell. A mathematical model for the direct alkaline fuel cell is developed based on reaction mechanism available in the literature to predict the cell voltage at a given current density. The model takes into account activation, ohmic, concentration overpotentials and other losses. The model prediction is in fair agreement with the experimental data on current-voltage characteristics and captures the influence of different experimental conditions on current-voltage characteristics. (C) 2007 Elsevier B.V. All rights reserved.