Alkaline, Fuel Cell Oxygen Electrodes Using Ag- and Pt-Loaded Carbon Catalysts

Abstract

In order to commercialize alkaline fuel cells, it is neccessary to reduce the cost without degrading the efficiency and life. In this study, the quantities of Ag and Pt catalysts for air electrodes were reduced by loading them on various carbon powders.
For the Ag catalyst, carbon powders with large surface area and high corrosion resistance were selected as the supports.50 wt% of Ag-colloidal graphite electrodes (9 mgAg/cm²) and 66.7 wt% of Ag-furnace black A electrodes (6 mg Ag/cm²) revealed small polarizations (Fig.7)and long lives (Fig.9).
For the Pt cataly st, acetylene black with high corrosion resistance was selected as the support. It was found that 14-20 cm² of Pt surface area per 1 cm²×1 μm of catalyst layer and more than 12 pm of the layer thickness are neccessary to get low polarization electrodes (Figs.12, 13). The Pt-acetylene black electrodes (0.3 mg Pt/cm²) showed better performance than the Ag-carbon electrodes (Table 3).