A separator for a fuel cell includes a separator base, crest sections, and trough sections. Regions surrounded by the respective trough sections and a corresponding electrode layer each constitute a passage that supplies oxidation gas or fuel gas to the electrode layer. A thin film having conductivity is placed at least on the top surface of each crest section. The thin film on the top surface of each crest section has a groove that connects the passages on the opposite sides of the crest section to each other. Each trough section has a flow resistance increasing portion on the downstream side of the groove in the flow direction of the gas. The flow resistance increasing portion reduces the cross-sectional flow area of the passage such that the cross-sectional flow area at the flow resistance increasing portion is smaller than that at the section to which the groove is connected.

A separator for a fuel cell includes a separator base, crest sections, and trough sections. Regions surrounded by the respective trough sections and a corresponding electrode layer each constitute a passage that supplies oxidation gas or fuel gas to the electrode layer. A thin film having conductivity is placed at least on the top surface of each crest section. The thin film on the top surface of each crest section has a groove that connects the passages on the opposite sides of the crest section to each other. Each trough section has a flow resistance increasing portion on the downstream side of the groove in the flow direction of the gas. The flow resistance increasing portion reduces the cross-sectional flow area of the passage such that the cross-sectional flow area at the flow resistance increasing portion is smaller than that at the section to which the groove is connected.

Disclosed herein is a fuel cell stack with improved manufacturing performance. The fuel cell stack includes: a separator that comprises a diffusion part, as being provided with a diffusion channel, configured to distribute reaction gas and cooling water and a reaction part, as being continuously formed from the diffusion part and provided with a reaction channel that has a height greater than that of the diffusion channel, configured to move reaction gas distributed from the diffusion part and generate electrons by a chemical reaction; and a gas diffusion layer configured to contact the separator at the diffusion part and the reaction part.

A fuel cell arrangement for carrying out a method for ascertaining the overvoltage of a working electrode in a fuel cell, in which the potential of a reference electrode compared to the grounded counter electrode is measured. For the measurement, a fuel cell comprising a polymer electrolyte membrane is used, in which the counter electrode comprises a lateral edge having at least one convexly curved region, and the electrolyte membrane surface, adjoining the counter electrode, comprises an electrode-free region in which the reference electrode is disposed on the electrolyte membrane surface. In contrast, the working electrode is continuous, which is to say has a large surface. The minimum distance L.sub.gap between the reference electrode and the edge of the counter electrode L.sub.gap=3×L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (Ω.sup.−1 cm.sup.−1), b.sub.ox=Tafel slope of the half cell for the electrochemical reaction of the working electrode, l.sub.m=membrane layer thickness (cm) and j.sub.ox.sup.0=exchange current density of the catalyst of the working electrode per unit of electrode surface in (A cm.sup.−2). This arrangement can advantageously be used to ensure that the potential measured at the hydrogen-fed reference electrode corresponds to the overvoltage of the working electrode with sufficient accuracy. The method can be applied to polymer electrolyte membrane fuel cells (PEMFC), to direct methanol fuel cells (DMFC) or to high-temperature fuel cells (SOFC).

A fuel cell arrangement for carrying out a method for ascertaining the overvoltage of a working electrode in a fuel cell, in which the potential of a reference electrode compared to the grounded counter electrode is measured. For the measurement, a fuel cell comprising a polymer electrolyte membrane is used, in which the counter electrode comprises a lateral edge having at least one convexly curved region, and the electrolyte membrane surface, adjoining the counter electrode, comprises an electrode-free region in which the reference electrode is disposed on the electrolyte membrane surface. In contrast, the working electrode is continuous, which is to say has a large surface. The minimum distance L.sub.gap between the reference electrode and the edge of the counter electrode L.sub.gap=3×L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (Ω.sup.−1 cm.sup.−1), b.sub.ox=Tafel slope of the half cell for the electrochemical reaction of the working electrode, l.sub.m=membrane layer thickness (cm) and j.sub.ox.sup.0=exchange current density of the catalyst of the working electrode per unit of electrode surface in (A cm.sup.−2). This arrangement can advantageously be used to ensure that the potential measured at the hydrogen-fed reference electrode corresponds to the overvoltage of the working electrode with sufficient accuracy. The method can be applied to polymer electrolyte membrane fuel cells (PEMFC), to direct methanol fuel cells (DMFC) or to high-temperature fuel cells (SOFC).

A plurality of anode wavy portions provided in an anode separator of a fuel cell have wavy patterns in the same phase, and are arranged in an amplitude direction of the anode wavy portions at a first pitch. A plurality of cathode wavy portions provided in a cathode separator have wavy patterns in the same phase but in reverse phase with respect to the anode wavy portions, and are arranged in an amplitude direction of the cathode wavy portions at a second pitch. The first pitch and the second pitch have different sizes.

A plurality of anode wavy portions provided in an anode separator of a fuel cell have wavy patterns in the same phase, and are arranged in an amplitude direction of the anode wavy portions at a first pitch. A plurality of cathode wavy portions provided in a cathode separator have wavy patterns in the same phase but in reverse phase with respect to the anode wavy portions, and are arranged in an amplitude direction of the cathode wavy portions at a second pitch. The first pitch and the second pitch have different sizes.

A combined roll is a roll of a wound strip that includes a plurality of layered bodies each including a polymer electrolyte membrane and a pair of electrode catalyst layers, and a supporting member including a plurality of frame units arranged in a single direction, with each frame unit supporting one layered body. The frame unit surrounds the electrode catalyst layers and is in contact with the electrode catalyst layers, with the outer periphery of the polymer electrolyte membrane held inside the frame unit in the thickness direction.

A combined roll is a roll of a wound strip that includes a plurality of layered bodies each including a polymer electrolyte membrane and a pair of electrode catalyst layers, and a supporting member including a plurality of frame units arranged in a single direction, with each frame unit supporting one layered body. The frame unit surrounds the electrode catalyst layers and is in contact with the electrode catalyst layers, with the outer periphery of the polymer electrolyte membrane held inside the frame unit in the thickness direction.

An electrochemical reaction cell comprising an anode electrode, a cathode electrode, and a membrane electrode assembly (MEA). The MEA is positioned between the anode electrode and the cathode electrode. The anode electrode, the cathode electrode, and the MEA each have a corrugated shape and are contained within a recess of a housing.