Joint separator, metal separator, and method of producing fuel cell stack

A metal separator to be incorporated into a fuel cell stack, wherein:

• the metal separator is applied with a compression load in a separator thickness direction when the metal separator is incorporated in the fuel cell stack;
• a metal bead as a seal is formed in the metal separator, the metal bead being elastically deformable by the compression load;
• the metal bead extends in a line pattern, the metal bead being formed integrally with the metal separator and protruding in the separator thickness direction;
• and
• a ratio of a bead width of the metal bead to a bead height is set to be within a range of not less than 4.5 and not more than 6.7, where the bead height is a protruding height of the metal bead.

A method of producing a fuel cell stack,

• the method comprising:
• a first preparing step of preparing a membrane electrode assembly, the membrane electrode assembly including an electrolyte membrane and electrodes provided on both sides of the electrolyte membrane;
• a second preparing step of preparing a joint separator formed by joining a first metal separator and a second metal separator together in a state where the first metal separator and the second metal separator are stacked together;
• a stacking step of stacking the membrane electrode assembly and the joint separator together alternately;
• and
• a load applying step of, after the stacking step, applying a compression load in a separator thickness direction to the membrane electrode assembly and the joint separator, wherein:
• in the second preparing step, a first metal bead as a seal is formed in the first metal separator, the first metal bead being elastically deformable by the compression load, and a second metal bead as a seal is formed in the second metal separator, the second metal bead being elastically deformable by the compression load;
• the first metal bead extends in a line pattern, the first metal bead being formed integrally with the first metal separator and protruding in a direction away from the second metal separator;
• the second metal bead extends in a line pattern, the second metal bead being formed integrally with the second metal separator and protruding in a direction away from the first metal separator;
• the first metal bead and the second metal bead have a same bead width;
• and
• a ratio of the bead width to a bead height is set to be within a range of not less than 2.25 and not more than 3.35, where the bead height is a distance between a protruding end of the first metal bead and a protruding end of the second metal bead.