Study of Internal Surface Distribution of Phosphoric Acid and Catalyst, and Analysis of Caused of Premature Life Expiration of Large Area Pressurized Phosphoric Acid Fuel Cell

After testing for the life time, the short-stack with a pressurized 1m2 cells have been dismantled and analyzed for the amount of residual phosphoric acid, diameter of platinum and the amount of remaining platinum in the cell electrode. As a result, it has been learned that the current density is a dominant factor for the increase of phosphoric acid on the anode electrode substrate. The other side, increase of phosphoric acid on the cathode electrode substrate are influenced by cell operating temperature and temperature of air outlet. And cathode electorocatalyst sintering are governed mainly by operating temperature and cathode potential. We had analyzed for causes of deteriorating the characteristics of the large area cells based on the residual amounts of phosphoric acid and retaining catalyst. As a result, it has been discovered that the influence of phosphoric acid is as dominant as that of sintering for ribbed electrode type cell.