Abstract: A fuel cell according to the present invention includes a power generation unit. The power generation unit is formed by stacking a first metal separator, a first membrane electrode assembly, a second metal separator, a second membrane electrode assembly, and a third metal separator. The number of flow grooves in a first oxygen-containing gas flow field is different from the number of flow grooves in a second oxygen-containing gas flow field. The first oxygen-containing gas flow field and the second oxygen-containing gas flow field have the same length, and the flow grooves in the first oxygen-containing gas flow field and the flow grooves in the second oxygen-containing gas flow field have the same depth.

Abstract: A fuel cell stack includes stacked unit fuel cells provided between end holding members, each unit fuel cell having a membrane electrode assembly including an anode and a cathode. A pair of separators respectively contact the anode and the cathode, and respectively form reaction gas passages between one separator and the anode, and between the other separator and the cathode. For each reaction gas passage, a gas supply passage and a gas discharge passage are formed through the unit fuel cells and one end holding member so that they communicate with the reaction gas passage of each unit fuel cell, and a drainage passage is also formed through the unit fuel cells and one end holding member. An end of the drainage passage and an end of the gas discharge passage on the side of the other end holding member are joined to each other.

Abstract: A first metal separator of one of adjacent power generation cells and a second metal separator of the other of the adjacent power generation cells are directly stacked together to form a coolant flow field. The first metal separator has a press line protruding toward the coolant flow field, between a fuel gas flow field and an inlet buffer. The second metal separator has a press line protruding toward the coolant flow field, between an oxygen-containing gas flow field and an inlet buffer. The press lines contact each other to limit flow of the coolant into a back surface buffer.

Abstract: In a first aging step, a plus electrode electric potential is applied to an anode of a fuel cell, and a minus electrode electric potential is applied to a cathode of the fuel cell. In this state, hydrogen pump operation is performed at maximum current density in use by supplying humidified hydrogen to the anode without supplying any oxygen-containing gas to the cathode. Thus, the hydrogen passes through a solid polymer electrolyte membrane toward the cathode. After the first aging step, in a second aging step, power generation of the fuel cell is performed at the maximum current density.

Abstract: A fuel gas flow field is formed on a surface of a rectangular first metal separator. The fuel gas flow field includes flow grooves extending in the direction of gravity. An outlet buffer is provided at a lower end of the fuel gas flow field. The outlet buffer includes an inclined surface inclined toward a fuel gas discharge passage. The fuel gas discharge passage is positioned below the outlet buffer. Outlet channel grooves are formed by ridges provided between the fuel gas discharge passage and the outlet buffer. Lower ends of the ridges are arranged in a zigzag pattern.

Abstract: A fuel cell stack having stacked unit fuel cells, each having a pair of separators between which a membrane electrode assembly is provided, which includes an anode and a cathode. Each separator has protruding lines arranged vertically in a zigzag manner, which protrude in a direction going away from the membrane electrode assembly. A space between the anode and the protruding lines of the separator facing the anode is used as a fuel gas passage. A space between the cathode and the protruding lines of the separator facing the cathode is used as an oxidant gas passage. At least part of the separators are each arranged in close contact with another separator so that a coolant passage through which a coolant flows horizontally is formed between both separators. A lower area of the coolant passage has a larger flow resistance than that of an upper area thereof.

Abstract: Each of power generation units of a fuel cell according to the present invention is formed by stacking a first metal separator, a first membrane electrode assembly, a second metal separator, a second membrane electrode assembly, and a third metal separator together. The power generation unit has therein a first oxygen-containing gas flow field, a first fuel gas flow field, a second oxygen-containing gas flow field, and a second fuel gas flow field. The number of flow grooves in the first oxygen-containing gas flow field is different from that of flow grooves in the second oxygen-containing gas flow field, and the number of flow grooves in the first fuel gas flow field is different from that of flow grooves in the second fuel gas flow field.

Abstract: In a first aging step, a plus electrode electric potential is applied to an anode of a fuel cell, and a minus electrode electric potential is applied to a cathode of the fuel cell. In this state, hydrogen pump operation is performed at maximum current density in use by supplying humidified hydrogen to the anode without supplying any oxygen-containing gas to the cathode. Thus, the hydrogen passes through a solid polymer electrolyte membrane toward the cathode. After the first aging step, in a second aging step, power generation of the fuel cell is performed at the maximum current density.

Abstract: A fuel cell according to the present invention includes a power generation unit. The power generation unit is formed by stacking a first metal separator, a first membrane electrode assembly, a second metal separator, a second membrane electrode assembly, and a third metal separator. The number of flow grooves in a first oxygen-containing gas flow field is different from the number of flow grooves in a second oxygen-containing gas flow field. The first oxygen-containing gas flow field and the second oxygen-containing gas flow field have the same length, and the flow grooves in the first oxygen-containing gas flow field and the flow grooves in the second oxygen-containing gas flow field have the same depth.

Abstract: Each of power generation units of a fuel cell according to the present invention is formed by stacking a first metal separator, a first membrane electrode assembly, a second metal separator, a second membrane electrode assembly, and a third metal separator together. The power generation unit has therein a first oxygen-containing gas flow field, a first fuel gas flow field, a second oxygen-containing gas flow field, and a second fuel gas flow field. The number of flow grooves in the first oxygen-containing gas flow field is different from that of flow grooves in the second oxygen-containing gas flow field, and the number of flow grooves in the first fuel gas flow field is different from that of flow grooves in the second fuel gas flow field.

Abstract: A first metal separator of one of adjacent power generation cells and a second metal separator of the other of the adjacent power generation cells are directly stacked together to form a coolant flow field. The first metal separator has a press line protruding toward the coolant flow field, between a fuel gas flow field and an inlet buffer. The second metal separator has a press line protruding toward the coolant flow field, between an oxygen-containing gas flow field and an inlet buffer. The press lines contact each other to limit flow of the coolant into a back surface buffer.

Abstract: A humidity sensor is disposed in a circulation passage as a passage of a hydrogen gas supplied to an anode of a fuel cell stack. A load current setting unit determines a level of electrical current supplied to a load. A flow rate controller controls a compressor based on the humidity detected by the humidity sensor and the load current determined by the load current setting unit to regulate a flow rate of the air supplied to a cathode of the fuel cell stack for maintaining the humidity of the hydrogen gas within a predetermined range less than 100%. The fuel cell stack generates the load current efficiently without discharging the hydrogen gas to the outside.

Abstract: A fuel gas flow field is formed on a surface of a rectangular first metal separator. The fuel gas flow field includes flow grooves extending in the direction of gravity. An outlet buffer is provided at a lower end of the fuel gas flow field. The outlet buffer includes an inclined surface inclined toward a fuel gas discharge passage. The fuel gas discharge passage is positioned below the outlet buffer. Outlet channel grooves are formed by ridges provided between the fuel gas discharge passage and the outlet buffer. Lower ends of the ridges are arranged in a zigzag pattern.

Abstract: A fuel cell stack having stacked unit fuel cells, each having a pair of separators between which a membrane electrode assembly is provided, which includes an anode and a cathode. Each separator has protruding lines arranged vertically in a zigzag manner, which protrude in a direction going away from the membrane electrode assembly. A space between the anode and the protruding lines of the separator facing the anode is used as a fuel gas passage. A space between the cathode and the protruding lines of the separator facing the cathode is used as an oxidant gas passage. At least part of the separators are each arranged in close contact with another separator so that a coolant passage through which a coolant flows horizontally is formed between both separators. A lower area of the coolant passage has a larger flow resistance than that of an upper area thereof.

Abstract: A fuel cell stack includes stacked unit fuel cells provided between end holding members, each unit fuel cell having a membrane electrode assembly including an anode and a cathode. A pair of separators respectively contact the anode and the cathode, and respectively form reaction gas passages between one separator and the anode, and between the other separator and the cathode. For each reaction gas passage, a gas supply passage and a gas discharge passage are formed through the unit fuel cells and one end holding member so that they communicate with the reaction gas passage of each unit fuel cell, and a drainage passage is also formed through the unit fuel cells and one end holding member. An end of the drainage passage and an end of the gas discharge passage on the side of the other end holding member are joined to each other.

Abstract: The concentration of a nitrogen gas in a circulatory supply passage connected to an anode is detected by a nitrogen concentration detector. Based on the detected concentration, the rotational speed of a pump disposed in the circulatory supply passage is controlled to adjust a hydrogen gas supplied to the anode in order to provide a desired stoichiometry for generating a target load current that is set by a target load current setting unit.

Abstract: A humidity sensor is disposed in a circulation passage as a passage of a hydrogen gas supplied to an anode of a fuel cell stack. A load current setting unit determines a level of electrical current supplied to a load. A flow rate controller controls a compressor based on the humidity detected by the humidity sensor and the load current determined by the load current setting unit to regulate a flow rate of the air supplied to a cathode of the fuel cell stack for maintaining the humidity of the hydrogen gas within a predetermined range less than 100%. The fuel cell stack generates the load current efficiently without discharging the hydrogen gas to the outside.

Abstract: The present invention makes it possible to remove an organic solvent in an electrode paste and fix an ion-conductive component while maintaining a desired moisture content. Specifically, a sheet of carbon paper applied with the electrode paste is horizontally held in a tank which comprises a drying apparatus. Water in the tank is brought to the boil by the aid of a first heater. Accordingly, the organic solvent in the electrode paste is removed, and the ion-conductive component is fixed, while forcedly humidifying the carbon paper and the electrode paste with steam.

Abstract: A fuel cell stack having unit cells and separators, in which each unit cell comprises a solid polymer electrolyte membrane having a pair of electrode catalysts attached on both surfaces, and a pair of collectors, each made of a rigid body, being in contact with respective electrode catalysts, and each of the separators comprises a pair of pressure generating plates defining therebetween a pressure chamber to which a pressurized fluid is introduced, the pressure generating plates being deformed by the pressurized fluid and pressed against the adjacent respective collectors.

Abstract: A fuel cell stack having unit cells and separators, in which each unit cell comprises a solid polymer electrolyte membrane having a pair of electrode catalysts attached on both surfaces, and a pair of collectors, each made of a rigid body, being in contact with respective electrode catalysts, and each of the separators comprises a pair of pressure generating plates defining therebetween a pressure chamber to which a pressurized fluid is introduced, the pressure generating plates being deformed by the pressurized fluid and pressed against the adjacent respective collectors.