Effects of Carbon Dioxide on the Performance of Anion-Exchange Membrane Fuel Cells

抄録

The effects of CO₂ on the performance of an anion-exchange membrane fuel cell were investigated using a three-electrode single cell equipped with a reference electrode. Though the membrane resistance decreased at high current densities in the presence of CO₂ via the self-purging mechanism, the cell voltage was significantly lower than that for pure O₂ especially at low current densities even at a very low CO₂ concentration of 100 ppm. The overpotential at the cathode was hardly changed by the presence of CO₂, while that at the anode significantly increased in the presence of CO₂. It was concluded that carbonate/bicarbonate ions accumulated at the anode during operation, and reduces the ionic conductivity and the pH in the anode catalyst layer, which results in a high overpotential at the anode.