Fuel cell stack assembly

A fuel cell stack assembly comprising:

• a plurality of fuel cell assemblies, each fuel cell assembly adjacent to at least one other fuel cell assembly;
• a first end plate at a first end of the plurality of fuel cell assemblies;
• a second end plate at a second opposing end of the plurality of fuel cell assemblies;
• and
• a tie rod configured to engage the first and second end plates and thereby apply a compression force to the plurality of fuel cell assemblies,
• wherein the tie rod is a unitary component that comprises a first engagement portion, a second engagement portion and an extending portion disposed partially between the first engagement portion and the second engagement portion and extending in an axial direction,
• wherein the first engagement portion and the second engagement portion are wider than the extending portion in a dimension perpendicular to the axial direction,
• wherein the extending portion comprises an inner section disposed between the first engagement portion and the second engagement portion and comprises a first outer section and a second outer section,
• wherein the first engagement portion separates the inner section and the first outer section and the second engagement portion separates the inner section and the second outer section,
• wherein a first engagement surface that engages with the first end plate is provided on the first engagement portion and a second engagement surface that engages with the second end plate is provided on the second engagement portion.