An electrochemical cell stack having a plurality of electrochemical cells stacked along a longitudinal axis. The electrochemical cells include a membrane electrode assembly comprising a cathode catalyst layer, an anode catalyst layer, and a polymer membrane interposed between the cathode catalyst layer and the anode catalyst layer. The electrochemical cells also include an anode plate and a cathode plate with the membrane electrode assembly interposed therebetween, and the anode plate defines a plurality of channels that form an anode flow field facing the anode catalyst layer. The electrochemical cells further include a cathode flow field positioned between the cathode plate and the cathode catalyst layer, wherein the cathode flow field comprises a porous structure.

An interconnector for a solid-oxide electrochemical cell stack of the embodiment includes: a metal base containing an iron-based alloy containing chromium; and a protective film provided on a surface of the metal base. The protective film includes a protective film body containing at least one selected from a spinel oxide and a perovskite oxide, and dispersed phases scattered in the protective film body and containing an oxide of at least one element selected from the group consisting of rare earth elements and zirconium.

An interconnector for a solid-oxide electrochemical cell stack of the embodiment includes: a metal base containing an iron-based alloy containing chromium; and a protective film provided on a surface of the metal base. The protective film includes a protective film body containing at least one selected from a spinel oxide and a perovskite oxide, and dispersed phases scattered in the protective film body and containing an oxide of at least one element selected from the group consisting of rare earth elements and zirconium.

A conductive member includes a base material and a covering part located on the base material and containing a first element. The base material contains chromium. The first element has a smaller value of first ionization energy and a smaller absolute value of free energy formation of oxide than chromium.

A conductive member includes a base material and a covering part located on the base material and containing a first element. The base material contains chromium. The first element has a smaller value of first ionization energy and a smaller absolute value of free energy formation of oxide than chromium.

A metal support for an electrochemical element where the metal support includes a plate face, has a plate shape as a whole, and has a warping degree of 1.5×10.sup.−2 or less determined by calculating a least square value through the least squares method using at least three points in the plate face of the metal support, calculating a first difference between the least square value and a positive-side maximum displacement value on a positive side with respect to the least square value and a second difference between the least square value and a negative-side maximum displacement value on a negative side that is opposite to the positive side with respect to the least square value, and dividing the sum of the first difference and the second difference by a maximum length of the plate face of the metal support that passes through a center of gravity.

In a metal support mostly used for a metal-supported solid oxide fuel cell (SOFC), a SOFC system that improves the power generation efficiency by allowing a gas to smoothly flow into or flow out from the through-holes is achieved. A metal support is formed in a plate shape as a whole and has a plurality of through-holes penetrating from a front surface on which an electrode layer is provided to a back surface, and the metal support has inclined through-holes, as the through-holes each of which has a central axis inclined with respect to a thickness direction.

In a metal support mostly used for a metal-supported solid oxide fuel cell (SOFC), a SOFC system that improves the power generation efficiency by allowing a gas to smoothly flow into or flow out from the through-holes is achieved. A metal support is formed in a plate shape as a whole and has a plurality of through-holes penetrating from a front surface on which an electrode layer is provided to a back surface, and the metal support has inclined through-holes, as the through-holes each of which has a central axis inclined with respect to a thickness direction.

A porous body comprises a framework having a three-dimensional network structure, the framework having a body including nickel and cobalt as constituent elements, the body of the framework including the cobalt at a proportion in mass of 0.2 or more and 0.8 or less relative to a total mass of the nickel and the cobalt, the framework having a surface with an arithmetic mean roughness of 0.05 μm or more, the porous body being increased in volume by 1% or more for a shape of an external appearance thereof after the porous body undergoes a heat treatment in the atmosphere at 800° C. for 200 hours with a load of 16 kPa applied.

A porous body comprises a framework having a three-dimensional network structure, the framework having a body including nickel and cobalt as constituent elements, the body of the framework including the cobalt at a proportion in mass of 0.2 or more and 0.8 or less relative to a total mass of the nickel and the cobalt, the framework having a surface with an arithmetic mean roughness of 0.05 μm or more, the porous body being increased in volume by 1% or more for a shape of an external appearance thereof after the porous body undergoes a heat treatment in the atmosphere at 800° C. for 200 hours with a load of 16 kPa applied.