A fuel cell stack including membrane-electrode assemblies and separators formed between each of the membrane-electrode assemblies is disclosed. The membrane-electrode assemblies may each include an electrolyte membrane, an anode formed on a first surface of the electrolyte membrane, and a cathode formed on a second surface of the electrolyte membrane. Each of the separators may include an anode separator facing the anode and a cathode separator facing the cathode. Each of the separators may include at least two manifolds, a channel separated from the manifolds and facing either the anode or the cathode, and a connection channel fluidly connecting the manifold and the channel. The separator may also include a buffer protrusion system in the connection channel configured to disperse the flow of the fuel or the oxidant.