An object is to equalize the level of cooling along a top-bottom direction of a fuel cell stack. A fuel cell stack has an anode-side separator placed between a plurality of membrane electrode assemblies. The anode-side separator comprises a separator center area that is arranged to face a power generation area of the membrane electrode assembly; an outer peripheral portion that is extended from the separator center area to outer periphery and has a plurality of openings for cooling medium supply manifolds; and a rib that is firmed from a beam portion provided to separate the adjacent openings for cooling medium supply manifolds from each other, over an area between the openings for cooling medium supply manifolds and the separator center area.

In order to improve usability of hybrid or fully electric aircraft, a fuel cell having improved efficiency and increased volume/weight specific energy density is provided. The fuel cell has a self-supporting membrane structure that is formed as a triply periodic level surface, which separates a first cavity supplied with gaseous fuel from a second cavity supplied with gaseous oxidizer in a gas-sealed manner while connecting the cavities in an ion-conductive manner.

In order to improve usability of hybrid or fully electric aircraft, a fuel cell having improved efficiency and increased volume/weight specific energy density is provided. The fuel cell has a self-supporting membrane structure that is formed as a triply periodic level surface, which separates a first cavity supplied with gaseous fuel from a second cavity supplied with gaseous oxidizer in a gas-sealed manner while connecting the cavities in an ion-conductive manner.

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=3L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (.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=3L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (.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 heat treatment apparatus for a fuel cell membrane-electrode assembly is provided. The heat treatment apparatus includes a hot press installed on upper and lower sides of feeding path to move in the vertical direction on a frame and which presses the electrode catalyst layers on upper and lower surfaces of the membrane-electrode assembly sheet. A plurality of gripper modules are installed at set intervals in a base member along a feeding direction of the membrane-electrode assembly sheet, and selectively grip both side edges of the membrane-electrode assembly sheet. A driving unit reciprocally moves the base member in a direction perpendicular to the feeding direction of the membrane-electrode assembly sheet and in the feeding direction of the membrane-electrode assembly sheet.

A heat treatment apparatus for a fuel cell membrane-electrode assembly is provided. The heat treatment apparatus includes a hot press installed on upper and lower sides of feeding path to move in the vertical direction on a frame and which presses the electrode catalyst layers on upper and lower surfaces of the membrane-electrode assembly sheet. A plurality of gripper modules are installed at set intervals in a base member along a feeding direction of the membrane-electrode assembly sheet, and selectively grip both side edges of the membrane-electrode assembly sheet. A driving unit reciprocally moves the base member in a direction perpendicular to the feeding direction of the membrane-electrode assembly sheet and in the feeding direction of the membrane-electrode assembly sheet.

The invention relates to 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=3L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (.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).

The invention relates to 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=3L.sub.l,r with (a) and (b), where m=ionic conductivity of the electrolyte membrane (.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).

Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. That substrate may be in nanobar form that conforms to an orientation imparted by a magnetic field or an electric field applied before or during the converting. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.