A PEM fuel
cell stack including one or more
fuel cells (1) arranged on top of one another, each of which contains a
membrane electrode assembly (2) between two
electrically conductive bipolar plates (3,4), the surfaces of which are equipped with flow channels (10) open on one side for the supply of reactive gases, whereby the membrane
electrode assemblies each comprise a
polymer electrolyte membrane (5), both sides of which are in contact with a
reaction layer (6,7), whereby the surface area of the reaction
layers is smaller than that of the
polymer electrolyte membrane and a compressible, coarse-pore gas distribution layer (8,9) made from carbon
fiber fabric is inserted between each
reaction layer and the adjacent bipolar plates congruent to the reaction lawyers along with seals (11,12) in the area outside the surface covered by the gas distribution
layers, whereby the gas distribution
layers in the no-load condition display a thickness D1 and the seals a thickness D2. The PEM fuel
cell stack is featured by the gas distribution layers in the PEM fuel
cell stack being compressed to 25 to 60% of the original thickness.