JP2008071676A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell stack of high mass productivity. <P>SOLUTION: A fuel cell stack of this invention is equipped with a plurality of cylindrical fuel cells and current collecting members to electrically connect the cells. Sheet layers comprising conductive metal particles and resin binder are provided to bond cells to current collecting members. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell stack and a fuel cell in which a plurality of fuel cells are electrically connected by a current collecting member.

A fuel cell includes a fuel cell stack in which a plurality of fuel cells each having a solid electrolyte sandwiched between a fuel electrode and an oxygen electrode are electrically connected by a current collecting member made of metal, an alloy, or ceramics. I have.

In a conventional fuel cell stack, a method of adhering a metal current collecting member and a fuel cell with an adhesive in which an epoxy resin is filled with nickel powder is used. (For example, Patent Document 1)
In the above method, although the bonding strength at the time of assembling the current collecting member and the fuel cell can be secured, since it is in the form of a paste, there is a possibility that dripping occurs when the adhesive is applied or dried.
In addition, when applying the adhesive, masking is necessary in order to avoid applying the current collector other than attaching the current collecting member, and the manufacturing process of the stack is complicated.
JP 2004-349262 A

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel cell stack excellent in mass productivity.

In order to achieve the above object, a fuel cell according to the present invention is a fuel cell comprising a cylindrical fuel cell and a current collecting member that electrically connects the plurality of fuel cells, the cell and the A sheet layer made of conductive metal particles and a resin binder, which adheres the current collecting member, is provided.

In a preferred aspect of the present invention, the conductive metal particles are nickel.

In a preferred aspect of the present invention, the adhesive resin binder is an acrylic resin and / or a rubber resin.

In the fuel cell stack of the present invention, the sheet layer made of conductive metal particles and a resin binder, that is, the cell and the current collecting member are bonded with a non-flowable uniform film, so that masking is performed like a paste, etc. This process is unnecessary, and the workability is improved, and it becomes possible to provide a fuel cell stack excellent in mass productivity.

The present invention will be described more specifically with reference to the following drawings.
In FIG. 1, the schematic which stuck the current collection member to the fuel cell used by this invention is shown. In the cell 5, an electrolyte 2 and a fuel electrode 3 are laminated on a cylindrical air electrode support 1. Further, an interconnector 4 for taking out electricity from the air electrode support 1 is formed continuously in the long axis direction of the cell.

FIG. 2 is a diagram illustrating an embodiment of the shape of the current collecting member used in the present invention.

FIG. 3 is a cross-sectional view showing an embodiment of a fuel cell stack according to the present invention. The four cells 5 are arranged with two interconnectors 4 in the horizontal direction and two in the vertical direction in parallel with the major axis direction with the interconnector 4 facing in the same direction. The cells 5 are electrically connected in series in the vertical direction of FIG. 3 and electrically connected in parallel in the horizontal direction using the adhesive conductive sheet 6 and the current collecting member 7.

The adhesive conductive sheet is composed of conductive metal particles and a resin binder. By adopting such a configuration, the adhesive conductive sheet can be made to have a uniform film thickness with a variation of several μm, and a sufficient contact area between the fuel cell and the current collecting member is ensured regardless of thermal history due to baking or power generation. Therefore, the cell and the current collecting member can be stably bonded.
Further, by using a sheet-like adhesive member having no fluidity, there is no fear of a short circuit without causing liquid dripping at the time of adhesion. As the resin binder having adhesiveness at room temperature contained in the adhesive conductive sheet, an acrylic resin, a rubber resin, or a mixture of an acrylic resin and a rubber resin can be suitably used. Acrylic resins and rubber resins are sticky at room temperature, and are decomposed and vaporized and removed by reducing gas containing hydrogen, water vapor, etc. at a temperature of about 700-1000 ° C, which is the operating temperature of the fuel cell. Is done.
Therefore, when the stack is manufactured, the cell stack in which the cell and the current collecting member are bonded due to the adhesiveness of the resin binder is added to the sheet after the heat history of about 700 to 1000 ° C. which is the operating temperature of the fuel cell is added. The conductive metal particles contained in the cell change to a state where the cell and the current collecting member are bonded, and the entire stack exhibits good electronic conductivity.

As the current collecting member, a heat-resistant metal material such as Inconel, stainless steel, nickel, or a conductive ceramic material can be suitably used. Moreover, the thing of appropriate shapes, such as a board | plate material, a mesh, felt, a foam, can be used. By forming the accordion shape as shown in FIG. 2, excellent elasticity can be obtained, and stress relaxation at the connecting portion between the fuel cell and the current collecting member can be effectively performed. .

As the conductive metal particles used for the adhesive conductive sheet, any material that is stable and has good conductivity in the use atmosphere can be used. For example, when the outer electrode of the cylindrical fuel cell is a fuel electrode, the adhesive conductive sheet is exposed to a reducing atmosphere, so it is preferable to use nickel, copper, or the like for the conductive metal particles. Nickel and copper are relatively inexpensive and are desirable in terms of cost reduction. Although the particle diameter of electroconductive metal particle is not specifically limited, For example, a thing with an average particle diameter of about 0.1-3.0 micrometers can be used suitably.

As a manufacturing method of the fuel cell stack of the present invention, for example, a slurry obtained by mixing a binder and conductive metal particles is formed into a sheet having a sheet shape by an appropriate method such as a doctor blade method, a cell, Or it can produce by bonding a cell and a current collection member, after affixing on a current collection member.
Since the connection between the cell and the current collecting member is performed by a sheet-like molded body, there is no liquid dripping that occurs when using a paste, a fluid adhesive, or the like, and the manufacture of the stack is easy. Further, it is possible to prevent a short circuit between the fuel electrode and the air electrode of the cell due to liquid dripping.

It is the schematic which affixed the current collection member on the fuel cell used by this invention. It is a figure explaining the shape of the current collection member used by this invention. It is sectional drawing which shows one Embodiment of the fuel cell stack in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air electrode 2 ... Electrolyte 3 ... Fuel electrode 4 ... Interconnector 5 ... Cell 6 ... Adhesive conductive sheet 7 ... Current collecting member

Claims (4)

A tubular fuel cell;
A fuel cell stack comprising a current collecting member for electrically connecting the plurality of cells,
A fuel cell stack comprising a sheet layer made of conductive metal particles and a resin binder for bonding the cell and the current collecting member. The fuel cell stack according to claim 1, wherein the conductive metal particles are nickel. The fuel cell stack according to any one of claims 1 to 3, wherein the resin binder is an acrylic resin and / or a rubber resin. A solid oxide fuel cell comprising the fuel cell stack according to claim 1.

Images