Separator for fuel cell, method for producing separator, and solid oxide fuel cell

Abstract

Gas discharge ports are provided in almost the entire area of a layer surface of a separator, and a gas for reaction is discharged like a shower from the separator toward a power generation cell. The separator is constructed by layering plate-shaped members containing iron-base alloy, nickel-base alloy, or chrome-base alloy as the base material. Silver, silver alloy, copper, or copper alloy is plated on both sides or one side of the base material of the plate-shaped member. The construction above can increase durability of a separator and enables the separator and a solid oxide fuel cell to be stably used for a long period.

Description

BACKGROUND OF THE INVENTION[0001]I. Technical Field[0002]The present invention relates to a separator for a fuel cell, a method for producing the separator, and a solid oxide fuel cell (SOFC).[0003]II. Description of the Related Art[0004]As is well known, the solid oxide fuel cell has been investigated and developed as one of various kinds of fuel cells for power generation. As the structure of the solid oxide fuel cell, there are proposed at present three types of structures: a cylindrical type, a monolithic type, and a flat plate laminated type. However, the flat plate laminated type structure is widely adopted for low-temperature operating type solid oxide fuel cell.[0005]In the flat plate laminated type solid oxide fuel cell, a fuel cell stack is constituted by alternately laminating power generation cells and separators in a state where a current collector is sandwiched between the power generation cell and the separator. The power generation cell has a laminated structure in w...

AI Technical Summary

Benefits of technology

The present invention provides a separator for fuel cell and a solid oxide fuel cell that can be used stably over a long period of time. The separator is designed to provide uniform gas concentration to the cell face and prevent power generation cell damage from carburization. The gas discharge ports are arranged on the layer surface of the separator in a way that the reactive gas can be discharged like a shower from the separator towards the power generation cell. The separator is formed by laminating multiple plate-shaped members with a groove hole or slit, and the inner flow passage for guiding the reactive gas is formed by plating the base material of the plate-shaped members. The use of the separator in the fuel cell stack results in improved power generation efficiency and prevention of mechanical failure by thermal stress. The method for producing the separator involves plating the surface of an iron based alloy, nickel based alloy, or chromium based alloy with silver, a silver alloy, copper, or a copper alloy.

Problems solved by technology

This results in a problem that electrode reaction may not be uniform on the cell face to cause deviation of current density distribution within the cell face and thereby the efficiency of the power generation cell (output power density per unit area) may be remarkably decreased.

Further, the electrode reaction as exothermic reaction which is not uniformly performed within the cell face, causes a temperature gradient to be formed in the power generation cell, as a result of which the power generation cell may be damaged by thermal stress in the course of the reaction.

However, the fuel cell in which the separator made of stainless steel is adopted, has a problem that when a hydrocarbon compound, such as methane, is used as fuel gas, carbon and carbon oxide are generated by reforming reaction, so that a part exposed to the fuel gas, such as the fuel passage wall surface of the separator, is carburized by the reaction product and thereby the separator deteriorates in the early stage.

Images