Provided is a fuel cell having excellent gas diffusivity and leading to suppressed pressure drop even with a porous body as a gas path. The fuel cell includes: plural stacked power generating unit cells each having a membrane assembly, an anode separator stacked on the membrane assembly on one side, and a cathode separator stacked on the membrane assembly on the other side, wherein the anode separator of any one of the power generating unit cells is stacked on the cathode separator of another one thereof that is adjacent to said any one, the cathode separator has a porous body where an oxidizing gas flows, and a path enlarging member, and the path enlarging member includes gas path enlarging portions that enlarge a path formed by the porous body, the gas path enlarging portions having wall parts inclining or orthogonal to a direction where the oxidizing gas flows.

In this fuel cell, a cathode-side porous film that covers a cathode electrode is interposed between the cathode electrode and an air supply layer, the cathode electrode constituting electrolyte film/electrode structures. In addition, breathing holes are formed in the cathode-side porous film, and the air flowing through air supply passages passes through the breathing holes and is supplied to the cathode electrode.

The invention relates to bipolar plates for electrochemical fuel cell assemblies, and in particular to configurations of bipolar plates allowing for multiple fluid flow channels for the passage of anode, cathode and coolant fluids. Embodiments disclosed include a bipolar plate (10) for an electrochemical fuel cell assembly, comprising: a first plurality of fluid flow channels (13) extending across a first face of the bipolar plate between first inlet and outlet ports (18a, 18b) at opposing ends of the bipolar plate; a second plurality of fluid flow channels (22) extending across a second opposing face of the bipolar plate between second inlet and outlet ports (21a, 21b) at opposing ends of the bipolar plate; and a third plurality of fluid flow channels (14) extending between third inlet and outlet ports (19a, 19b) at opposing ends of the bipolar plate, the third plurality of fluid flow channels provided between first and second corrugated plates (11, 12) forming the first and second opposing faces of the bipolar plate, wherein the first, second and third fluid flow channels are coplanar.

The invention relates to bipolar plates for electrochemical fuel cell assemblies, and in particular to configurations of bipolar plates allowing for multiple fluid flow channels for the passage of anode, cathode and coolant fluids. Embodiments disclosed include a bipolar plate (10) for an electrochemical fuel cell assembly, comprising: a first plurality of fluid flow channels (13) extending across a first face of the bipolar plate between first inlet and outlet ports (18a, 18b) at opposing ends of the bipolar plate; a second plurality of fluid flow channels (22) extending across a second opposing face of the bipolar plate between second inlet and outlet ports (21a, 21b) at opposing ends of the bipolar plate; and a third plurality of fluid flow channels (14) extending between third inlet and outlet ports (19a, 19b) at opposing ends of the bipolar plate, the third plurality of fluid flow channels provided between first and second corrugated plates (11, 12) forming the first and second opposing faces of the bipolar plate, wherein the first, second and third fluid flow channels are coplanar.

A fuel cell joint separator includes a passage bead and an outer bead. In a dual seal section where the passage bead and the outer bead extend next to each other, a ridge protruding from one surface of a metal separator is formed integrally with the metal separator, between the passage bead and the outer bead. The height of the ridge is smaller than the height of the bead seal compressed by the tightening load. A joining line is provided between the outer bead and the ridge.

A fuel cell joint separator includes a passage bead and an outer bead. In a dual seal section where the passage bead and the outer bead extend next to each other, a ridge protruding from one surface of a metal separator is formed integrally with the metal separator, between the passage bead and the outer bead. The height of the ridge is smaller than the height of the bead seal compressed by the tightening load. A joining line is provided between the outer bead and the ridge.

A bipolar plate is provided including an outlet port and an inlet port with at least one flow field having a plurality of ducts connecting the inlet port to the outlet port, and with at least one bypass duct at a side of the at least one flow field. A flow resistance in the at least one bypass duct is determined by the design of the at least one bypass duct. A blocking element does not project into a cross section of the at least one bypass duct.

A bipolar plate is provided including an outlet port and an inlet port with at least one flow field having a plurality of ducts connecting the inlet port to the outlet port, and with at least one bypass duct at a side of the at least one flow field. A flow resistance in the at least one bypass duct is determined by the design of the at least one bypass duct. A blocking element does not project into a cross section of the at least one bypass duct.

A flow battery with a mixed-flow architecture comprising two electrodes separated by a membrane. The electrodes and membrane are sandwiched between a pair of bipolar plates. The architecture comprises a flow-field disposed between each of the electrodes and the membrane, wherein each flow-field is configured with channels for the flow of electrolyte. The flow fields can be made of any electrically non-conducting and acid resistant material such as PE, PP, PVDF and PTFE, or any other acid resistant plastic. The flow-fields are porous to enable ion conductivity. The presence of the flow-fields enables reduction in the thickness of the electrodes and bipolar plates thereby decreasing the ohmic loss and the cost.

A flow battery with a mixed-flow architecture comprising two electrodes separated by a membrane. The electrodes and membrane are sandwiched between a pair of bipolar plates. The architecture comprises a flow-field disposed between each of the electrodes and the membrane, wherein each flow-field is configured with channels for the flow of electrolyte. The flow fields can be made of any electrically non-conducting and acid resistant material such as PE, PP, PVDF and PTFE, or any other acid resistant plastic. The flow-fields are porous to enable ion conductivity. The presence of the flow-fields enables reduction in the thickness of the electrodes and bipolar plates thereby decreasing the ohmic loss and the cost.