Solid-oxide-electrolysis-cell-type hydrogen production apparatus

A solid-oxide-electrolysis-cell-type hydrogen production apparatus comprising:

• a cell structure including a first electrode, a second electrode, and an electrolyte layer interposed between the first electrode and the second electrode, the electrolyte layer containing an ionically conductive solid oxide;
• a gas diffusion layer having a pair of main surfaces facing away from each other, the gas diffusion layer being disposed adjacent to the first electrode, a first main surface of the pair of main surfaces facing the first electrode, the gas diffusion layer supplying a gas to the first electrode;
• and
• a gas channel plate having a pair of plate surfaces facing away from each other, the gas channel plate being disposed adjacent to the gas diffusion layer, a first plate surface of the pair of plate surfaces facing a second main surface of the gas diffusion layer, the gas channel plate supplying the gas to the gas diffusion layer,
• wherein the gas diffusion layer is formed of a porous metal body having a three-dimensional mesh-like skeleton,
• the gas channel plate includes a first region, a second region, and a third region,
• the first region, the second region, and the third region are arranged in order of the first region, the second region, and the third region from a second plate surface of the gas channel plate toward the first plate surface of the gas channel plate in a thickness direction,
• a first channel extending through the first region in the thickness direction of the gas channel plate is provided in the first region,
• a second channel extending through the second region in the thickness direction of the gas channel plate is provided in the second region,
• a third channel extending through the third region in the thickness direction of the gas channel plate is provided in the third region,
• the first channel extends to the second plate surface of the gas channel plate and communicates with the second channel,
• the second channel communicates with the third channel,
• the third channel extends to the first plate surface of the gas channel plate and communicates with the gas diffusion layer,
• the first channel includes a slit extending from a center of the first plate surface toward an outer edge of the first plate surface at an boundary surface between the first region and the second region when viewed in a normal direction to the first plate surface, and
• letting a total area of the first channel at the boundary surface between the first region and the second region when viewed in the normal direction be a first opening area S1,
• letting a total area of the second channel at a boundary surface between the second region and the third region when viewed in the normal direction be a second opening area S2, and
• letting a total area of the third channel at a boundary surface between the third region and the second main surface of the gas diffusion layer when viewed in the normal direction be a third opening area S3, a relationship S2<S1<S3 is satisfied.