Electrolyte membrane for fuel cell operable in medium temperature range, fuel cell using the same, and manufacturing methods therefor

The invention provides an electrolyte membrane that allows an operating temperature of a solid polymer membrane fuel cell to be increased, and an operating temperature of a solid oxide fuel cell to be lowered. This electrolyte membrane can be used in a fuel cell that is operable in an intermediate temperature range. The invention also provides a fuel cell using such an electrolyte membrane. According to the invention, dense layers (21, 22 and 24) made of hydrogen permeable metal are provided on both sides of a polymer electrolyte layer (20) in a solid polymer membrane fuel cell. Consequently, the run-off of moisture contained in the electrolyte layer (20) can be inhibited. Moreover, the operating temperature of the fuel cell can be raised. On the other hand, in a solid oxide fuel cell, a dense layer made of a hydrogen permeable metal is employed as a substrate (43, 53), and electrolyte layers are formed on the substrate. Consequently, the electrolyte layers can be made sufficiently thin, and furthermore, the operating temperature of the solid oxide fuel cell can be lowered.