| 摘要 |
A fuel cells stack of the present invention includes a plurality of unit cells, which are laid one upon another. Each unit cell has a hydrogen electrode and an oxygen electrode, which are disposed across an electrolyte membrane. The electrolyte membrane is a hydrogen ion exchange membrane, which is mainly composed of a sulfonic acid group-containing perfluorocarbon polymer. The electrolyte membrane is designed to have a varying concentration of sulfonic acid group in such a manner that the concentration of sulfonic acid group in a contact area, where the electrolyte membrane is in contact with the hydrogen electrode, is approximately one tenth of the concentration of sulfonic acid group in a residual area. The electromotive force of the unit cell varies according to a difference in hydrogen ion concentration between the hydrogen electrode and the oxygen electrode. The varying concentration of sulfonic acid group enables the hydrogen ion concentration in the contact area, where the electrolyte membrane is in contact with the hydrogen electrode, to be lower than the hydrogen ion concentration in an opposite contact area, where the electrolyte membrane is in contact with the oxygen electrode, on an occasion of power generation. This arrangement desirably enhances the electromotive force per unit cell. <IMAGE> |
