Disclosed is a stainless steel having excellent surface electrical conductivity for a fuel cell separator. According to an embodiment of the disclosed stainless steel having excellent surface electrical conductivity for a fuel cell separator, a value of the following surface oxide atomic ratio (1) may be 0.5 or less, as measured on the surface of a stainless steel containing 15 wt % or more of Cr by X-ray angle-resolved photoemission spectroscopy using an Al-Kα X-ray source under the condition where a take-off angle of photoelectrons is from 12° to 85°.

[00001]$\begin{array}{cc}\frac{\begin{array}{c}\mathrm{sum}\mathrm{of}\mathrm{atomic}\mathrm{concentrations}\left(\mathrm{at}\%\right)\\ \mathrm{of}\mathrm{metal}\mathrm{elements}\mathrm{in}\mathrm{metal}\mathrm{oxide}\left(\mathrm{MO}\right)\end{array}}{\begin{array}{c}\mathrm{sum}\mathrm{of}\mathrm{atomic}\mathrm{concentrations}\left(\mathrm{at}\%\right)\\ \mathrm{of}\mathrm{metal}\mathrm{elements}\mathrm{in}\mathrm{total}\mathrm{oxides}\mathrm{and}\mathrm{hydroxides}\end{array}}& \left(1\right)\end{array}$

The metal oxide (MO) includes a mixed oxide: M represents an alloying element other than Cr and Fe or a combination thereof in the matrix; and O represents oxygen. The total oxides and hydroxides include a Cr oxide, a Cr hydroxide, an Fe oxide, an Fe hydroxide, and the metal oxide (MO).

Disclosed is a stainless steel having excellent surface electrical conductivity for a fuel cell separator. According to an embodiment of the disclosed stainless steel having excellent surface electrical conductivity for a fuel cell separator, a value of the following surface oxide atomic ratio (1) may be 0.5 or less, as measured on the surface of a stainless steel containing 15 wt % or more of Cr by X-ray angle-resolved photoemission spectroscopy using an Al-Kα X-ray source under the condition where a take-off angle of photoelectrons is from 12° to 85°.

[00001]$\begin{array}{cc}\frac{\begin{array}{c}\mathrm{sum}\mathrm{of}\mathrm{atomic}\mathrm{concentrations}\left(\mathrm{at}\%\right)\\ \mathrm{of}\mathrm{metal}\mathrm{elements}\mathrm{in}\mathrm{metal}\mathrm{oxide}\left(\mathrm{MO}\right)\end{array}}{\begin{array}{c}\mathrm{sum}\mathrm{of}\mathrm{atomic}\mathrm{concentrations}\left(\mathrm{at}\%\right)\\ \mathrm{of}\mathrm{metal}\mathrm{elements}\mathrm{in}\mathrm{total}\mathrm{oxides}\mathrm{and}\mathrm{hydroxides}\end{array}}& \left(1\right)\end{array}$

The metal oxide (MO) includes a mixed oxide: M represents an alloying element other than Cr and Fe or a combination thereof in the matrix; and O represents oxygen. The total oxides and hydroxides include a Cr oxide, a Cr hydroxide, an Fe oxide, an Fe hydroxide, and the metal oxide (MO).

A cell stack device includes at least one cell and at least one conductive member. The cell includes an element portion. The conductive member includes a base member containing chromium, a first layer containing an oxide containing zinc, and a zinc spinel portion located at the interface between the base member and the first layer. The first layer includes a first region facing the element portion. A first overlap area ratio, at which the zinc spinel portion located at a first interface between the first region and the base member overlaps with the first interface, is less than a second overlap area ratio, at which the zinc spinel portion located at a second interface between a second region where the surface of the first layer is exposed to an oxidizing atmosphere and the base member overlaps with the second interface.

A cell stack device includes at least one cell and at least one conductive member. The cell includes an element portion. The conductive member includes a base member containing chromium, a first layer containing an oxide containing zinc, and a zinc spinel portion located at the interface between the base member and the first layer. The first layer includes a first region facing the element portion. A first overlap area ratio, at which the zinc spinel portion located at a first interface between the first region and the base member overlaps with the first interface, is less than a second overlap area ratio, at which the zinc spinel portion located at a second interface between a second region where the surface of the first layer is exposed to an oxidizing atmosphere and the base member overlaps with the second interface.

The invention relates to a bipolar plate (1) for a fuel cell, comprising a bipolar plate substrate (2) composed of stainless steel and comprising a coating (3), which is applied to the bipolar plate substrate (2), for increasing the corrosion resistance of the bipolar plate (1). According to the invention, the coating (3) is of single- or multi-layer design and has at least one layer (4) composed of a metal matrix (5) with non-passivating dispersoid particles (6) incorporated therein. The invention further relates to a fuel cell having at least one bipolar plate (1) according to the invention.

Disclosed is a stainless steel for a fuel cell separator, more specifically, a stainless steel for a fuel cell separator having a low contact resistance. According to an embodiment of the stainless steel for a fuel cell separator disclosed herein, an arithmetic mean summit curvature Ssc of the surface defined according to the ISO 25178 standard is at least 6.0 μm.sup.−1, a root mean square surface slope Sdq is at least 23, and a contact resistance is at most 10 mΩ.Math.cm.sup.2.

Disclosed is a stainless steel for a fuel cell separator, more specifically, a stainless steel for a fuel cell separator having a low contact resistance. According to an embodiment of the stainless steel for a fuel cell separator disclosed herein, an arithmetic mean summit curvature Ssc of the surface defined according to the ISO 25178 standard is at least 6.0 μm.sup.−1, a root mean square surface slope Sdq is at least 23, and a contact resistance is at most 10 mΩ.Math.cm.sup.2.

The present specification relates to a connecting material for a solid oxide fuel cell, comprising a conductive substrate; and a ceramic protective film provided on one surface of the conductive substrate, in which the ceramic protective film comprises an oxide represented by Formula 1, a manufacturing method thereof, and a solid oxide fuel cell comprising the same.

The present specification relates to a connecting material for a solid oxide fuel cell, comprising a conductive substrate; and a ceramic protective film provided on one surface of the conductive substrate, in which the ceramic protective film comprises an oxide represented by Formula 1, a manufacturing method thereof, and a solid oxide fuel cell comprising the same.

A layer system for coating a metal substrate in order to form a flow field plate includes at least one cover layer made of metal oxide; at least one intermediate layer, which supports the cover layer; and a lower layer, which supports the intermediate layer(s). The cover layer is formed of indium tin oxide; wherein the indium tin oxide is optionally doped with at least one element from the group comprising carbon, nitrogen, boron, fluorine, hydrogen, silicon, titanium, tin and zirconium. At least one intermediate layer is formed of titanium nitride and/or titanium carbide and/or titanium carbonitride and/or titanium niobium nitride and/or titanium niobium carbide and/or titanium niobium carbonitride and/or chromium nitride and/or chromium carbide and/or chromium carbonitride. The lower layer is formed of titanium or a titanium-niobium alloy or chromium.