Bipolar plate having a variable width of the reaction gas channels in the inlet region of the active region, fuel-cell stack and fuel-cell system having bipolar plates of this type, as well as a vehicle

A system, comprising:

• a first gas diffusion layer including a first membrane;
• a second gas diffusion layer including a second membrane;
• and
• a bipolar plate coupled between the first gas diffusion layer and the second gas diffusion layer, the bipolar plate including:
• a separator plate including a plurality of reaction gas channels and a plurality of coolant gas channels, the separator plate further including an active region comprised of an intake region and a remaining region, wherein a first width of the plurality of reaction gas channels in the intake region is different than a second width of the plurality of reaction gas channels in the remaining region, the first width continuously changing across the intake region, the second width constant across the remaining region, wherein the intake region comprises between 5 and 30% of a length of the active region.

A method comprising:

• providing reaction gases to a gas diffusion layer through a plurality of reaction gas channels in a bipolar plate having an active region including an intake region in fluid communication with a remaining region, a width of the plurality of reaction gas channels in the intake region being less than a width of the plurality of reaction gas channels in the remaining region, wherein the width of the plurality of reaction gas channels in the intake region continuously increases across the active region, the width of the plurality of reaction gas channels is constant across the remaining region, and the active region comprises between 5 and 30% of a total length of the active region;
• hydrating the gas diffusion layer with coolant passing through a plurality of coolant channels in the bipolar plate;
• and
• maintaining humidity of a membrane in the gas diffusion layer above an allowed minimum humidity for a reaction in the active region.