Electrochemical systems comprising separator plates and the separator plates comprising a first individual plate and a second individual plate. The individual plate comprising: an electrochemically active region, at least one through-opening and a sealing bead. Conveying channels adjoin a bead flank of the sealing bead and the conveying channels connecting the through-opening and the sealing bead interior. A plurality of first weld sections connecting the two individual plates and the first weld sections extend in the direction of the first conveying channels and arranged between the first conveying channels.

A gas channel forming plate is arranged between a membrane electrode assembly and a flat separator base. The gas channel forming plate includes gas channels arranged on a surface that faces the membrane electrode assembly, water channels each formed on the back side of the protrusion between an adjacent pair of the gas channels, communication passages that connect the gas channels and the water channels to each other, and guide portions formed by causing an inner wall surface of a gas channel to protrude inward in the gas channel. The guide portions are formed such that the upstream edge of each communication passage is arranged in a range in which, in the velocity vector of the gas flowing in the gas channel, the directional component directed from the side corresponding to the membrane electrode assembly toward the flat separator base has a positive value.

A fuel cell includes a power-generation channel provided on a surface of a cathode-side separator which faces a MEA and a cooling channel provided on a surface of the cathode-side separator opposite to the MEA. Air flows through the power-generation channel and the cooling channel. The cooling channel is separated from the power-generation channel by a side wall. The cross-sectional area of the power-generation channel on the air outlet side is smaller than that of the power-generation channel at a position upstream of the air outlet side, and the cross-sectional area of the cooling channel on the air outlet side is larger than that of the cooling channel at a position upstream of the air outlet side. A through-hole is provided in a side wall that separates the power-generation channel from the cooling channel.

A fuel cell includes a power-generation channel provided on a surface of a cathode-side separator which faces a MEA and a cooling channel provided on a surface of the cathode-side separator opposite to the MEA. Air flows through the power-generation channel and the cooling channel. The cooling channel is separated from the power-generation channel by a side wall. The cross-sectional area of the power-generation channel on the air outlet side is smaller than that of the power-generation channel at a position upstream of the air outlet side, and the cross-sectional area of the cooling channel on the air outlet side is larger than that of the cooling channel at a position upstream of the air outlet side. A through-hole is provided in a side wall that separates the power-generation channel from the cooling channel.

A fuel cell is provided with a power generation unit; the power generation unit is provided with a first metal separator, a first electrolyte membrane/electrode structure, a second metal separator, a second electrolyte membrane/electrode structure, and a third metal separator. The first electrolyte membrane/electrode structure is provided with a first resin frame member at the outer periphery, and the first resin frame member is provided with an inlet buffer section positioned outside a power generation region and coupled to a first oxidant gas flow path, and a protruding section, which is one part of an inlet coupling flow path coupling together the inlet buffer section and an oxidant gas inlet communication hole.

A fuel cell gas supply and diffusion layer includes a sheet-like porous body layer, and a plurality of gas passage grooves formed on one surface of the porous body layer in parallel and formed in a zigzag shape or a wave shape respectively. As viewed in a plan view, a first rectangular region where circumscribes one gas passage groove and a second rectangular region where circumscribes a gas passage groove adjacent to the one gas passage groove overlap along a region in contact each other. An overlapping region where the first rectangular region and the second rectangular region overlap exists at any depth position of the grooves. According to the fuel cell gas supply and diffusion layer, it is possible to increase a power generation efficiency of a fuel cell.

A unit cell of a fuel cell includes a membrane electrode assembly and a cathode side separator and an anode side separator sandwiching the membrane electrode assembly. An oxygen-containing gas supply passage connected to an oxygen-containing gas flow field is formed in the cathode side separator. The oxygen-containing gas supply passage has a rectangular shape extending in a flow field width direction of the oxygen-containing gas flow field. The width of the opening of the oxygen-containing gas supply passage on the short side is increased from the end side to the central side in the flow field width direction.

A unit cell of a fuel cell includes a membrane electrode assembly and a cathode side separator and an anode side separator sandwiching the membrane electrode assembly. An oxygen-containing gas supply passage connected to an oxygen-containing gas flow field is formed in the cathode side separator. The oxygen-containing gas supply passage has a rectangular shape extending in a flow field width direction of the oxygen-containing gas flow field. The width of the opening of the oxygen-containing gas supply passage on the short side is increased from the end side to the central side in the flow field width direction.

A plurality of channel elements provided in a bipolar plate have different widths depending on positions, so that the velocity of flow of the fluid increases from an inlet toward an outlet of the bipolar plate and water generated when the fluid is condensed on the downstream side of the bipolar plate can be discharged more smoothly. In addition, a plurality of channel elements have different contact angles depending on positions of the plurality of channel elements so that the contact angle increases toward the outlet side of the bipolar plate. Thus, the reaction gas can be more concentrated on the surface of a gas diffusion layer. Even if the concentration of the reaction gas is reduced at the outlet side of the bipolar plate, the diffusion of the reaction gas is well performed, so that performance reduction can be prevented.

A plurality of channel elements provided in a bipolar plate have different widths depending on positions, so that the velocity of flow of the fluid increases from an inlet toward an outlet of the bipolar plate and water generated when the fluid is condensed on the downstream side of the bipolar plate can be discharged more smoothly. In addition, a plurality of channel elements have different contact angles depending on positions of the plurality of channel elements so that the contact angle increases toward the outlet side of the bipolar plate. Thus, the reaction gas can be more concentrated on the surface of a gas diffusion layer. Even if the concentration of the reaction gas is reduced at the outlet side of the bipolar plate, the diffusion of the reaction gas is well performed, so that performance reduction can be prevented.