An electrically conductive member of the present disclosure includes a base member containing chromium (Cr), and a first layer provided on a surface of the base member and containing chromium(III) oxide (Cr.sub.2O.sub.3). The first layer also contains titanium (Ti).

An electrically conductive member of the present disclosure includes a base member containing chromium (Cr), and a first layer provided on a surface of the base member and containing chromium(III) oxide (Cr.sub.2O.sub.3). The first layer also contains titanium (Ti).

A high-temperature polymer electrolyte membrane fuel cell stack may include a plurality of cell units; a cooling assembly including a plurality of first independent cooling plates disposed on top surfaces of the plurality of cell units, respectively, and a plurality of second independent cooling plates disposed on bottom surfaces of the plurality of cell units, respectively; and a support assembly configured to support the plurality of cell units and the cooling assembly.

Provided herein are CO.sub.2-selective membranes that can be used to efficiently separate CO.sub.2 and CO. The membranes can be used to produce high-purity CO.sub.2 and CO gas streams from a feed gas stream comprising a mixture of CO.sub.2 and CO (e.g., an exhaust gas stream from a fuel cell, such as a solid oxide fuel cell). In this way, the membranes can be used with a solid oxide fuel cell system to covert CO.sub.2 to CO.

A cell stack device includes a cell stack, a holding member, and a positive electrode terminal. The cell stack is constructed by stacking a plurality of cells. The holding member holds the cells. The positive electrode terminal functions as a positive electrode when power generated by the cell stack is output to the outside. The potential of the positive electrode terminal is not more than that of the holding member.

A fuel cell system has a cell (1) that is capable of generating electric power. The cell (1) has a fuel electrode (1a), an air electrode (1b) and an electrolyte (1c). The fuel electrode (1a) is supplied with hydrogen obtained by reforming fuel gas. The air electrode (1b) is supplied with oxygen in the air. The electrolyte (1c) is interposed between the fuel electrode (1a) and the air electrode (1b) to enable oxygen ions to pass through to the fuel electrode (1a). A water vapor retaining mechanism (6) is disposed in a flow path of the fuel gas supplied to the fuel electrode (1a). The mechanism (6) retains water vapor generated in the fuel electrode (1a) during electric power generation by the cell (1). The mechanism (6) enables the water vapor to be mixed with the fuel gas.

A fuel cell system has a cell (1) that is capable of generating electric power. The cell (1) has a fuel electrode (1a), an air electrode (1b) and an electrolyte (1c). The fuel electrode (1a) is supplied with hydrogen obtained by reforming fuel gas. The air electrode (1b) is supplied with oxygen in the air. The electrolyte (1c) is interposed between the fuel electrode (1a) and the air electrode (1b) to enable oxygen ions to pass through to the fuel electrode (1a). A water vapor retaining mechanism (6) is disposed in a flow path of the fuel gas supplied to the fuel electrode (1a). The mechanism (6) retains water vapor generated in the fuel electrode (1a) during electric power generation by the cell (1). The mechanism (6) enables the water vapor to be mixed with the fuel gas.

A fuel cell cassette for forming a fuel cell stack along a fuel cell axis includes a cell retainer, a plate positioned axially to the cell retainer and defining a space axially with the cell retainer, and a fuel cell having an anode layer and a cathode layer separated by an electrolyte layer. The outer perimeter of the fuel cell is positioned in the space between the plate and the cell retainer, thereby retaining the fuel cell and defining a cavity between the cell retainer, the fuel cell, and the plate. The fuel cell cassette also includes a seal disposed within the cavity for sealing the edge of the fuel cell. The seal is compliant at operational temperatures of the fuel cell, thereby allowing lateral expansion and contraction of the fuel cell within the cavity while maintaining sealing at the edge of the fuel cell.

A fuel cell cassette for forming a fuel cell stack along a fuel cell axis includes a cell retainer, a plate positioned axially to the cell retainer and defining a space axially with the cell retainer, and a fuel cell having an anode layer and a cathode layer separated by an electrolyte layer. The outer perimeter of the fuel cell is positioned in the space between the plate and the cell retainer, thereby retaining the fuel cell and defining a cavity between the cell retainer, the fuel cell, and the plate. The fuel cell cassette also includes a seal disposed within the cavity for sealing the edge of the fuel cell. The seal is compliant at operational temperatures of the fuel cell, thereby allowing lateral expansion and contraction of the fuel cell within the cavity while maintaining sealing at the edge of the fuel cell.

A fuel cell system including a fuel cell, an off-gas reprocessing unit that is provided downstream of the fuel cell and that at least partially removes at least one of steam or carbon dioxide from an off-gas discharged from the fuel cell, a flow passage that is provided downstream of the off-gas reprocessing unit and that allows a reprocessed off-gas discharged from the off-gas reprocessing unit to flow therethrough, and a controlling unit that modulates the reaction constant K.sub.pa of a reaction A with respect to the reprocessed off-gas discharged from the off-gas reprocessing unit, to 1.22 or more.