A fuel cell stack includes a first metal separator and a second metal separator sandwiching a membrane electrode assembly. Bead seals are provided on the first and second metal separators. The bead seals protrude toward the membrane electrode assembly. A seal member is provided on a top part of each of the bead seals. In the process of producing the fuel cell stack, pressure medium is supplied to a coolant flow field formed between the first metal separator and the second metal separator. The supply pressure of the pressure medium is set to not less than the supply pressure of a coolant supplied to the coolant flow field during normal operation of the fuel cell stack.

A fuel cell, of proton-exchange-membrane type, includes, stacked in the following order: a first terminal, an end anode plate, a plurality of membrane plates having a bipolar plate between every two membrane plates, an end cathode plate and a second terminal Each bipolar plate includes, preassembled in the following order: a medial cathode plate and a medial anode plate, each medial anode, end anode, medial cathode and end cathode plate comprising at least one duct for distributing a reactant. The anode end plate is produced by a bipolar plate of the same orientation, and an anode capable of obturating all of the ducts of the medial cathode plate of this bipolar plate. The cathode end plate is produced by a bipolar plate of the same orientation, and a cathode capable of obturating all of the ducts of the medial anode plate of this bipolar plate.

A fuel cell, of proton-exchange-membrane type, includes, stacked in the following order: a first terminal, an end anode plate, a plurality of membrane plates having a bipolar plate between every two membrane plates, an end cathode plate and a second terminal Each bipolar plate includes, preassembled in the following order: a medial cathode plate and a medial anode plate, each medial anode, end anode, medial cathode and end cathode plate comprising at least one duct for distributing a reactant. The anode end plate is produced by a bipolar plate of the same orientation, and an anode capable of obturating all of the ducts of the medial cathode plate of this bipolar plate. The cathode end plate is produced by a bipolar plate of the same orientation, and a cathode capable of obturating all of the ducts of the medial anode plate of this bipolar plate.

Fuel cell unit in the form of a fuel cell stack for producing electrical energy in an electrochemical manner, comprising fuel cells, the fuel cells each comprising a proton exchange membrane, an anode, a cathode, a gas diffusion layer, a bipolar plate, at least one fluid channel for the passage of a fluid, at least one seal (11) composed of a sealing material (42) for sealing off the at least one fluid channel (37), wherein particles (41) composed of a particle material (43) are arranged in the sealing material (42) of the at least one seal (11), for the purpose of extending the diffusion path (38) of the fluid which is sealed off by the at least one seal (11).

Fuel cell unit in the form of a fuel cell stack for producing electrical energy in an electrochemical manner, comprising fuel cells, the fuel cells each comprising a proton exchange membrane, an anode, a cathode, a gas diffusion layer, a bipolar plate, at least one fluid channel for the passage of a fluid, at least one seal (11) composed of a sealing material (42) for sealing off the at least one fluid channel (37), wherein particles (41) composed of a particle material (43) are arranged in the sealing material (42) of the at least one seal (11), for the purpose of extending the diffusion path (38) of the fluid which is sealed off by the at least one seal (11).

A method for producing a multi-layer bipolar plate for an electrochemical device is disclosed. The method includes producing at least one sealing element made of an elastic material on a first bipolar plate layer of the bipolar plate; connecting the first bipolar plate layer with the sealing element produced thereon and a second bipolar plate layer of the bipolar plate by welding along at least one connection welding seam, in which method an impairment to the sealing element produced on the first bipolar plate layer as a result of a subsequent welding operation can be reliably avoided and the freedom of design of the electrochemical unit is preferably increased, and that during the welding operation, the second bipolar plate layer faces toward a welding energy source and that during the welding operation, a weld pool produced by the welding energy source does not completely penetrate the first bipolar plate layer.

An object of the present invention is to provide a photocurable resin composition having a high curing degree after irradiation with light while maintaining cured material characteristics such as high extensibility and high strength. Provided is a photocurable resin composition including the following ingredients (A) to (C): ingredient (A): a polyisobutylene resin containing one or more (meth)acryloyl groups and a —[CH.sub.2C(CH.sub.3).sub.2]— unit; ingredient (B): ingredient (b1): an acrylate monomer having an alicyclic hydrocarbon group having 5 to 25 carbon atoms, and ingredient (b2): an acrylate monomer having a linear or branched alkyl group having 11 to 30 carbon atoms; and ingredient (C): a photo-radical polymerization initiator.

An object of the present invention is to provide a photocurable resin composition having a high curing degree after irradiation with light while maintaining cured material characteristics such as high extensibility and high strength. Provided is a photocurable resin composition including the following ingredients (A) to (C): ingredient (A): a polyisobutylene resin containing one or more (meth)acryloyl groups and a —[CH.sub.2C(CH.sub.3).sub.2]— unit; ingredient (B): ingredient (b1): an acrylate monomer having an alicyclic hydrocarbon group having 5 to 25 carbon atoms, and ingredient (b2): an acrylate monomer having a linear or branched alkyl group having 11 to 30 carbon atoms; and ingredient (C): a photo-radical polymerization initiator.

A fuel cell includes a membrane electrode assembly, an anode gas diffusion layer, and a cathode gas diffusion layer, a pair of separators for clamping a laminate made up of the membrane electrode assembly, the anode gas diffusion layer and cathode gas diffusion layer, and a frame that is formed from thermosetting resin and disposed between the separators to surround a periphery of the laminate. At least one of the anode gas diffusion layer and cathode gas diffusion layer is formed from a composite of thermoplastic resin and conductive particles, and includes a protrusion that protrudes beyond a level of a surface of the frame which faces one of the pair of separators in a state that the laminate is not clamped between the separators under a predetermined pressure. The one of the separators presses the protrusion and gets the at least one of the gas diffusion layers to be deformed and put into contact with the frame in a state that the laminate is clamped between the separators under the predetermined pressure.

A fuel cell includes a membrane electrode assembly, an anode gas diffusion layer, and a cathode gas diffusion layer, a pair of separators for clamping a laminate made up of the membrane electrode assembly, the anode gas diffusion layer and cathode gas diffusion layer, and a frame that is formed from thermosetting resin and disposed between the separators to surround a periphery of the laminate. At least one of the anode gas diffusion layer and cathode gas diffusion layer is formed from a composite of thermoplastic resin and conductive particles, and includes a protrusion that protrudes beyond a level of a surface of the frame which faces one of the pair of separators in a state that the laminate is not clamped between the separators under a predetermined pressure. The one of the separators presses the protrusion and gets the at least one of the gas diffusion layers to be deformed and put into contact with the frame in a state that the laminate is clamped between the separators under the predetermined pressure.