Hot compression process for making edge seals for fuel cells

A hot compression process for making edge seals for fuel cells, comprised of pairs of electrode assemblies with a matrix seal disposed between the electrodes of each pair, each pair of assemblies disposed between two gas-conducting plates comprising the steps of:

• forming a rectangular-shaped electrode assembly to a nominal size larger than a finished size, the assembly having opposed sides, one side for contacting a gas-conducting plate and the opposed side for conducting a matrix seal;
• applying at least one bead of elastomer to a peripheral band adjacent the peripheral margins on each opposed side of the electrode assembly so that the beads on the opposing sides are aligned;
• providing a pair of press platens;
• heating the press platens to a temperature generally in the range of 180.degree. C. to 230.degree. C.;
• compressing the electrode assembly with the elastomer applied thereto between the heated press platens for a sufficient period and with a force sufficient to cause the beads to permeate the entire thickness of the adjacent assembly so that there is essentially no buildup of the elastomer between the platen and the electrode assembly and the elastomer forms a generally gas impervious seal adjacent the peripheral margins, the seal extending from one opposed side of the assembly to the other for preventing gas leakage across the peripheral margins for the assembly;
• removing the electrode assembly from between the platens;
• allowing the removed electrode assembly to cool to ambient temperature;
• and
• trimming the cooled electrode assembly to a finished size.