Provided are a metal plate configured such that sufficient strength and performance are ensured and the workability and cost of mass production are improved, and an electrochemical element and the like including the metal plate. A metal plate 1 includes a thick portion 110, and a thin portion 120 that is thinner than the thick portion 110. The thin portion 120 is provided with a penetration space 1c passing through the thin portion 120 in the thickness direction.

A porous body includes a framework having a three-dimensional network structure, the framework having a body including crystal grains including nickel and cobalt as constituent elements, the cobalt having a proportion in mass of 0.2 or more and 0.8 or less with respect to a total mass of the nickel and the cobalt, the crystal grains having a shorter grain diameter of 2 μm or more, as determined in a first observed image obtained by observing the body of the framework in cross section at a magnification of 200 times.

A porous body includes a framework having a three-dimensional network structure, the framework having a body including crystal grains including nickel and cobalt as constituent elements, the cobalt having a proportion in mass of 0.2 or more and 0.8 or less with respect to a total mass of the nickel and the cobalt, the crystal grains having a shorter grain diameter of 2 μm or more, as determined in a first observed image obtained by observing the body of the framework in cross section at a magnification of 200 times.

A fuel cell stack includes: a substrate; a first fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the first fuel cell being a single fuel cell; a second fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the second fuel cell being a single fuel cell; an interconnector film electrically connecting the fuel side electrode of the first fuel cell and the oxygen side electrode of the second fuel cell; and a porous ceramic film covering at least the interconnector film in a region between the fuel side electrode of the first fuel cell and the fuel side electrode of the second fuel cell.

A fuel cell stack includes: a substrate; a first fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the first fuel cell being a single fuel cell; a second fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the second fuel cell being a single fuel cell; an interconnector film electrically connecting the fuel side electrode of the first fuel cell and the oxygen side electrode of the second fuel cell; and a porous ceramic film covering at least the interconnector film in a region between the fuel side electrode of the first fuel cell and the fuel side electrode of the second fuel cell.

A fuel cell electricity generation unit including a unit cell including an electrolyte layer containing a solid oxide, and a cathode and an anode which face each other with the electrolyte layer intervening therebetween; an electrically conductive current collecting member disposed on the cathode side of the unit cell; an electrically conductive coating which covers the surface of the current collecting member; and an electrically conductive bonding layer which bonds the cathode to the current collecting member covered with the coating, wherein the following relationship is satisfied: the porosity of the coating<the porosity of the bonding layer<the porosity of the cathode.

A single fuel cell according to the present disclosure includes a power generation section, a power non-generation section which does not include the power generation section, and an oxygen-ion-insulating gas seal film arranged so as to cover the surface of the power non-generation section, and the gas seal film is configured by a structure formed by firing a material containing MTiO.sub.3 (M: alkaline earth metal element) and metal oxide. The structure may include a first structure and a second structure which are different in composition, the first structure may include components derived from MTiO.sub.3 in larger amounts than the second structure, the second structure may include a metal element contained in the metal oxide in a larger amount than the first structure, and the area ratio of the second structure in the structure may be not less than 1% and not more than 50%.

An electrochemical device comprises a first type of membrane disposed between first and second reservoirs containing an input solution, and a second type of membrane, different from the first type, is disposed between a first redox-active electrolyte chamber and the first reservoir and disposed between a second redox-active electrolyte chamber and the second reservoir. The first type of membrane and one of the second type of membranes form a membrane pair and the pair has an area specific resistance below y=5065.3x.sup.3−1331.1x.sup.2+90.035x+39 Ohm cm.sup.2 when the pair is equilibrated in an electrolyte and for at least part of a range where 0<x<0.4 and x is the mass fraction of salt in the electrolyte.

A cell may include a columnar support having a first main face and a second main face; and an element comprising a first electrode layer, a solid electrolyte layer, and a second electrode layer laminated in sequence on the first main face of the support. The porosity of at least one of the two end portions of the support in the longitudinal direction L may be lower than that of the central portion of the support in the longitudinal direction L.

Disclosed is a gas diffusion layer for a fuel cell that may be made thinner by integrally forming a base and a fine pore layer, and a method for manufacturing the same. A gas diffusion layer for a fuel cell which constitutes a unit cell of the fuel cell includes: a base layer formed by impregnating a first slurry, in which carbon powder and polytetrafluoroethylene (PTFE) are mixed, in the interior of a carbon fiber base; and a fine pore layer formed by coating a second slurry, in which carbon powder and polytetrafluoroethylene (PTFE) are mixed and which has a viscosity that is higher than the viscosity of the first slurry, on a surface of the base layer.