Abstract
An experiment was conducted for the improvement of wettability of oxygen electrodes with activated carbon. Charcoal activated with ammonia gas at 950° C (activated carbon) was fluorinated in view of the fact that graphite fluoride has low surface energy. Adsorption isotherms of water on the activated carbon and its fluorination products were determined to evaluate change in wettability with fluorination. It was found that water adsorption isotherms for the activated carbon and its low fluorination products were typically S-shaped and that the micropores in these samples play an important role on the adsorption of water. These samples at low relative pressure had adsorption behavior similar to each other and the amount of water adsorbed on the samples was proportional to relative pressure. Significant differences, however, were observed for measured adsorbed volume and heat of adsorption between the activated carbon and its fluorination product. On the other hand, the high fluorination products adsorbed only a small amount of water in the whole range of relative pressure. This hydrophobic phenomenon is due to the low surface energy of graphite fluoride. These results suggest that the activated carbon partially fluorinated will be useful for the improvement of wettability of oxygen electrode with activated carbon.
