Fuel cell stack

A method for use in manufacturing a fuel cell stack:

• assembling a membrane electrode assembly to have a membrane between a first gas diffusion layer and a second gas diffusion layer;
• locating the membrane electrode assembly between a first fluid flow plate and a second fluid flow plate;
• locating a bypass blocker at a space between the first gas diffusion layer of the membrane electrode assembly and a seal,
• the space bounded vertically from a longitudinal axis of the membrane electrode assembly by a first fluid flow plate, the first fluid flow plate having a first height extending normal relative to the longitudinal axis defining a first surface and a second height extending normal relative to the longitudinal axis defining a second surface,
• wherein the first height of the first surface and the second height of the second surface are different and the first height extends further normal relative to the longitudinal axis than the second height;
• and
• deforming the blocker at the space within the length of the second surface and avoiding deforming the blocker at the space within the length of the first surface such that a first portion of the blocker at the space within the length of the first surface and a second portion of the blocker at the space within the length of the second surface have different heights such that the blocker inhibits a bypass flow of a reactant through the space from a first side of the first gas diffusion layer to a second side of the first gas diffusion layer in a direction of flow of the reactant during operation of the fuel cell.