Abstract: A water electrolysis cell includes a separator having, on its front and back, grooves serving as channels. The separator has, in its ends in a planar direction, an oxygen electrode- side supply hole, an oxygen electrode-side discharge hole, a hydrogen electrode-side supply hole, a hydrogen electrode-side discharge hole, an inter-cell channel supply hole, and an inter-cell channel discharge hole, as viewed in plan. A sealing member surrounding the oxygen electrode-side supply hole and a sealing member surrounding the oxygen electrode- side discharge hole, as viewed in plan, are located in the separator, but no sealing members are located around the hydrogen electrode-side supply hole, the hydrogen electrode-side discharge hole, the inter-cell channel supply hole, and the inter-cell channel discharge hole.

Abstract: In the water electrolysis system, the water electrolysis system includes a water electrolysis cell stack and a reaction water supply device, and the water electrolysis system gradually increases the supply amount of the reaction water to the oxygen electrode by the reaction water supply device so that a pressure value on an oxygen electrode side of the water electrolysis cell stack does not become higher than a pressure value on a hydrogen electrode side of the water electrolysis cell stack when the water electrolysis system is activated.

Abstract: A water electrolysis cell includes an electrolyte membrane that is sandwiched between two catalyst layers, the two catalyst layers, two microporous layers each of which is disposed adjacent to a surface of each of the catalyst layers opposite to the electrolyte membrane side, two gas diffusion layers each of which is disposed adjacent to a surface of each of the microporous layers opposite to the catalyst layer side, and two separators each of which is disposed adjacent to a surface of each of the gas diffusion layers opposite to the microporous layer side. In the water electrolysis cell, an area of one of an oxygen electrode and a hydrogen electrode is smaller than an area of the other, and adhesion strength between each of the microporous layers and each of the catalyst layers is higher than that between each of the gas diffusion layers and each of the microporous layers.

Abstract: A fuel cell stack includes a plurality of single cells stacked and a manifold. The plurality of single cells each include a first separator including a seal portion surrounding the manifold and including a hollow protrusion and a fluid passage portion allowing the fluid to flow between the manifold and a space on the opposite side of the seal portion from the manifold via the hollow of the seal portion, a second separator disposed on the side opposite to the side on which the seal portion projects, of the first separator, and an electric insulating frame disposed on the opposite side of the second separator from the first separator. The second separator includes a flat-and-bulge portion in a surface facing the seal portion, along an abutment region of the seal portion and the electric insulating frame.

Abstract: A fuel cell includes: a membrane electrode assembly; cathode and anode-side water-repellent layers; a cathode-side separator that includes a cathode gas passage and an air exhaust manifold communicated to the cathode gas passage. The cathode gas passage includes a water exhaust inhibiting portion and a water storage portion. The water exhaust inhibiting portion is provided on a lowermost passage positioned on a lowermost side in a gravity direction. The water storage portion is provided upstream of the water exhaust inhibiting portion such that liquid water is stored in the water storage portion by the water exhaust inhibiting portion. A liquid water connection portion is provided in the water-repellent layer so as to pass through the water-repellent layer such that liquid water flows between the catalyst layer and the water storage portion.

Abstract: A fuel cell stack includes a plurality of single cells stacked and a manifold. The plurality of single cells each include a first separator including a seal portion surrounding the manifold and including a hollow protrusion and a fluid passage portion allowing the fluid to flow between the manifold and a space on the opposite side of the seal portion from the manifold via the hollow of the seal portion, a second separator disposed on the side opposite to the side on which the seal portion projects, of the first separator, and an electric insulating frame disposed on the opposite side of the second separator from the first separator. The second separator includes a flat-and-bulge portion in a surface facing the seal portion, along an abutment region of the seal portion and the electric insulating frame.

Abstract: A fuel cell includes: a membrane electrode assembly; cathode and anode-side water-repellent layers; a cathode-side separator that includes a cathode gas passage and an air exhaust manifold communicated to the cathode gas passage. The cathode gas passage includes a water exhaust inhibiting portion and a water storage portion. The water exhaust inhibiting portion is provided on a lowermost passage positioned on a lowermost side in a gravity direction. The water storage portion is provided upstream of the water exhaust inhibiting portion such that liquid water is stored in the water storage portion by the water exhaust inhibiting portion. A liquid water connection portion is provided in the water-repellent layer so as to pass through the water-repellent layer such that liquid water flows between the catalyst layer and the water storage portion.