JPH1079260A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell of laminate type which can widely adopt materials to separator other than the known material conventionally while the electro-conducting function, gas separating function, etc., required of a separator are well secured. SOLUTION: This fuel cell 1 is constituted so that unit cells 5 each formed by installing an anode 3 and cathode 4 on an electrolyte matrix 2 and separator plates 6 are laminated one over another. Each separator plate 6 comprises of a separator body 10 and a conductive member 20 penetrating the separator body 10, wherein the shaft 21 penetrates the body 10 between its cathode end pinching part 13 and anode end pinching part 17, and the surface of the flat plate part 22 protrudes a little from the surface of the cathode end pinching part 13 and is put in pressure contact with the end of the cathode 4, and the foremost part 23 of the shaft 21 protrudes a little from the surface of the anode end pinching part 17 and is put in pressure contact with the end of the anode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacked fuel cell in which unit cells and separators are alternately stacked, and more particularly to an improvement in a separator for a phosphoric acid type or solid polymer type fuel cell.

[0002]

2. Description of the Related Art A stacked fuel cell is constituted by fastening a cell stack in which unit cells each having an anode and a cathode via an electrolyte layer and separators are alternately stacked, from both ends. In order to supply anode gas (hydrogen-rich fuel gas) to the anode side and cathode gas (air) to the cathode side of each cell, a gas channel is formed between the separator, the anode and the cathode. I have.

As a form of a gas channel, there are cases where a gas channel is formed on a surface of a separator, a plate having a gas channel formed on a separator is stacked, and a gas channel is formed on an anode and a cathode. In any case, the material of the separator is required to have strength enough to withstand the pressure for tightening the battery stack and to be gas-impermeable in order to play a role of separating the anode gas and the cathode gas. .

[0004] Further, since the separator also serves to electrically connect the unit cells adjacent in the stacking direction, a conductive material is used. From such a point, conventionally, as a material of the separator, in a fuel cell operated at a high temperature such as a solid electrolyte type or a molten carbonate type, a heat-resistant metal or conductive ceramic is used, and phosphoric acid is used. In a fuel cell operated at a relatively low temperature, such as a fuel cell or a polymer electrolyte fuel cell, a gas-impermeable dense carbon material is often used.

[0005]

However, a separator made of a metal or a conductive ceramic is expensive to manufacture and expensive. In addition, carbon material separators are inexpensive compared to metals and conductive ceramics, but baked paper etc. to make carbon plates,
Since it is manufactured through a process of cutting it into a predetermined shape, mass production cannot be said to be easy, and there remains a problem of manufacturing cost.

[0006] Therefore, it is desired to improve mass productivity and reduce costs by manufacturing a separator by using alternative materials, but it is difficult to find alternative materials to the above materials. It is.
For example, if an inexpensive material such as a heat-resistant plastic having electrical conductivity is developed, mass production by injection molding using a carbon material instead of a carbon material in a phosphoric acid type or solid polymer type fuel cell separator can be reduced. Although it is considered that the cost can be reduced, a material that can substitute for the carbon material hardly appears in practice.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a fuel cell of a stacked type with a material other than those conventionally used as a material of the separator, while ensuring the necessary conductive function and gas separating function. It is intended to provide a product that can be widely used.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a fuel cell comprising a cell stack in which a unit cell having an anode and a cathode disposed via an electrolyte layer and a separator are alternately stacked. In at least one of the separators, a plate-shaped separator main body, a first current collecting surface that is provided through the separator main body and is exposed on one surface of the separator main body, and a second current collector surface that is exposed on the other surface of the separator main body And a conductive member electrically connecting the anode of the unit cell on the first current collecting surface side and the cathode of the unit cell on the second current collecting surface side.

Thus, the function of conducting the unit cells adjacent to the separator is ensured by the conductive member without using a conductive material for the separator body. Therefore, various materials such as plastic and ceramic can be used as the material of the separator body. here,
If the conductive member is provided in a region outside the region where the gas channel is formed in the separator main body, the flow of gas passing through the gas channel is not hindered by the conductive member, and the gas is provided where the conductive member is provided. Is less likely to leak.

On the surface of the separator body, an anode end holding portion for holding the anode end and a cathode end holding portion for holding the cathode end are formed, and the first current collecting surface of the conductive member is connected to the anode end. If it is exposed to the holding portion and the second current collecting surface is exposed to the cathode end holding portion, the first current collecting surface and the end of the anode and the second current collecting surface and the end of the cathode are pressed against each other. An electrical connection is made.

The conductive member is disposed on the surface of the shaft core penetrating through the separator body, the first planar current collector disposed on the surface of the anode end clamping portion, and the surface of the cathode end clamping portion. With the planar second current collecting portion, the electrical connection between the anode and the cathode and the conductive member can be favorably performed. In addition, if the separator body is made of a resin having heat resistance at the operating temperature of the fuel cell, mass production of the separator body can be easily performed using a method such as injection molding. Further, since the separator has the elasticity of the resin, the gas sealing property can be improved.

The use of graphitized carbon or copper as the material of the conductive member is preferable because good contact with the electrode can be obtained and heat resistance and touch resistance are excellent.

[0013]

Embodiments of the present invention will be described below. (Embodiment 1) [Description of Overall Configuration of Fuel Cell] FIG. 1 is an assembly diagram showing a configuration of a main part of a phosphoric acid type fuel cell according to an embodiment of the present invention.

This fuel cell 1 has an electrolyte matrix 2
A cell 5 having an anode 3 and a cathode 4 disposed therein;
A laminate formed by alternately laminating the separator plates 6 is:
It is configured to be fastened in the stacking direction by an end plate (not shown). Although FIG. 1 shows only one unit cell 5, the number of unit cells 5 in the fuel cell 1 is set according to the cell voltage to be output.

The electrolyte matrix 2 is formed by impregnating phosphoric acid into a rectangular sheet formed by binding silicon carbide with a fluorine resin. Each of the anode 3 and the cathode 4 is approximately the same size as the electrolyte matrix 2, and carbon particles carrying a platinum catalyst or a platinum alloy catalyst are bonded to a water-repellent carbon paper with a fluororesin. It is a sheet obtained by pressing and crimping the sheet produced.

The separator plate 6 includes a separator body 10
And four conductive members 2 penetrating through the separator body 10
0. The separator body 10 is a flat molded body having the same size as the electrolyte matrix 2, and a large number of gas channels 11 are formed and ribs 12 are formed on the surface on the side facing the cathode 4, A cathode end sandwiching portion 13 is formed in a band shape on both outer sides at the same height as the rib 12, and an edge seal portion 14 is formed in a band shape on both outer sides. On the other hand, on the surface of the separator body 10 on the side facing the anode 3, a number of gas channels 15 are cut and ribs 16 are formed in a direction perpendicular to the gas channels 11, and ribs 16 are formed on both outer sides thereof. The anode end sandwiching portion 17 is formed in a band shape at the height of
Are formed in a belt shape.

The cathode 4 and the anode 3 have ends on the cathode end holding portion 13 and the anode end holding portion 17.
Since there is no electrode above the edge seal portion 14, the edge seal portion 14 is formed higher than the cathode end holding portion 13 by the thickness of the cathode 4, and the edge seal portion 18 is formed higher than the anode end holding portion 17 by the thickness of the anode 3. Have been.

In the fuel cell 1 having such a configuration, each gas channel 1 is passed through an external manifold (not shown).
5 is supplied with hydrogen gas as an anode gas, and each gas channel 11 is supplied with air as a cathode gas.
Power generation is performed by maintaining a predetermined operating temperature of about 200 ° C. [Detailed Description of Separator Plate] The separator body 10 is formed of an insulating material. This material needs to have heat resistance at the operating temperature of the fuel cell 1 and strength to withstand the pressure for tightening the end plate, and it is preferable that the material has acid resistance because it comes into contact with phosphoric acid vapor, and satisfies such conditions. Resins and ceramics can be used.

In the case of resin, it is desirable that the separator main body 10 can be easily mass-produced by using a method such as injection molding. In addition, since the resin has elasticity, the sealing property in the edge seal portion 14 is improved. It is also preferable in that it can be performed. Specific examples of preferred resins in terms of physical properties and cost include polyphenylene sulfide, polysulfone, and polyether sulfone. Fluororesins such as polytetrafluoroethylene are also excellent in physical properties.

FIG. 2 is a perspective view showing the appearance of the conductive member 20. As shown in the figure, the conductive member 20 is a T-shaped member having a cylindrical shaft portion 21 and a rectangular flat plate portion 22 and is entirely formed of a conductive material. An O-ring 24 is mounted around the root of the shaft 21. As shown in FIG. 1, the four conductive members 20 are provided in the vicinity of the four corners of the separator main body 10 where the cathode end holding portion 13 and the anode end holding portion 17 intersect.

FIG. 3 is a sectional view taken along the line XX of the fuel cell 1 shown in FIG. 1 and is a drawing cut along the cathode end sandwiching portion 13. As shown in the figure, a through hole having substantially the same shape as the conductive member 20 is formed in the separator body 10, and the conductive member 20 has an O-ring 24 fitted around the base of the shaft portion 21. In this state (see FIG. 2), it is inserted into the through hole.

In this state, the shaft 21 is connected to the separator body 1.
0 and the flat plate portion 22 penetrates between the cathode end holding portion 13 and the anode end holding portion 17.
Slightly protrudes from the surface of the anode 4 and is pressed against the end of the cathode 4.
Slightly protruding from the surface of the anode 3 and pressed against the end of the anode 3.

Accordingly, the flat plate portion 22 can collect current from the cathode 4 in contact therewith, and the tip portion 23 can collect current from the anode 3 in contact therewith. Further, two unit cells 5 adjacent to each other with the separator body 10 interposed therebetween are connected in series by the conductive member 20. Further, since the flat plate portion 22 is sealed by being pressed against the inner surface 25 of the through hole via the O-ring 24, the anode gas and the cathode gas do not pass through the through hole.

The material of the conductive member 20 needs to have conductivity and heat resistance, preferably has acid resistance, and has a good current collecting effect at the flat plate portion 22 and the tip portion 23 pressed against the electrode. To ensure this, it is preferable to have some elasticity. As a specific example, besides expandable graphite (for example, CARBOFIT manufactured by Hitachi Chemical Co., Ltd.), copper which is relatively flexible among metals can be mentioned.
In the case of copper, gold plating is applied to the surface, so that the contact resistance becomes more excellent.

The O-ring 24 has acid resistance, heat resistance,
Use is made of an elastic fluororesin or the like. Here, the O-ring 24 is inserted around the root of the shaft 21, but the O-ring 24 may be inserted in the middle of the shaft 21. In addition to using the O-ring 24 as a method of sealing the through hole, the conductive member 20 may be used.
May be filled with a fluorine resin adhesive or the like in the gap between the hole and the through-hole, and if the conductive member 20 and the separator body 10 are made of a material having sufficient elasticity, it is not particularly necessary to use a sealing material. .

In the present embodiment, the shape of the conductive member 20 is a T-shape including the shaft portion 21 and the flat plate portion 22. However, the shape of the conductive member is not limited to this, and various shapes such as those described below are provided. It can be shaped. An H-shape in which flat portions are formed on both sides of the shaft. It consists only of a shaft without a flat plate.

[0027] A prismatic shaft portion is formed instead of a cylindrical shaft portion. Also, as described above, the conductive member 20 is provided at the position where the cathode end holding portion 13 and the anode end holding portion 17 intersect. When the conductive member 20 is provided at this position, the gas flow in the gas channels 11 and 15 is restricted by the conductive member. This is because there is no possibility that the gas flows into the through hole without being hindered by the through hole 20.

Although it is possible to penetrate the conductive member where the gas channels 11 and 15 are formed, in this case, it is necessary to seal the through hole so that gas does not flow as in the present embodiment. Not easy. Further, in the present embodiment, the conductive members 20 are provided at the four corners of one separator main body 10. However, the number and the contact area of the conductive members provided on the separator main body are different from each other in terms of the current collecting effect of the conductive members on the cathode and the anode. It may be determined in consideration of the above. Normal,
The larger the area of the anode and the cathode, the more difficult it is to collect current. Therefore, it is necessary to increase the number of conductive members and increase the contact area. On the other hand, when the area of the separator is small, current collection is easy, so the number of conductive members may be small. For example, if one conductive member can obtain a sufficient current collecting effect, only one conductive member is provided. Is also good.

(Embodiment 2) The fuel cell of this embodiment has the same configuration as the fuel cell 1 of Embodiment 1,
The separator body 30 instead of the separator body 10
The difference is that a conductive member 40 is used instead of the conductive member 20. FIG. 4 is an external perspective view of the conductive member 40 used in the present embodiment, and FIG. 5 is an exploded perspective view of a main part thereof.

As shown in FIG. 4, the conductive member 40 is L-shaped and made of the same material as the conductive member 20, and has a first member 41 comprising a cylindrical shaft portion 42 and a band-shaped flat plate portion 43.
And a second member 44 composed of a cylindrical shaft portion 45 and a flat plate portion 46 are engaged with each other at the distal ends of the shaft portion 42 and the shaft portion 45 to be combined. The shaft portion 42 and the shaft portion 45
As shown in FIG. 5, a protrusion 45 a formed at the tip of the shaft 45 is inserted into and engaged with a recess 42 a formed at the tip of the shaft 42.

FIG. 6 is a plan view showing a state in which two conductive members 40 are fitted in the separator main body 30.
The separator main body 30 has the same configuration as the separator main body 10, and as shown in FIG. 6, the cathode end holding portion 13, the anode end holding portion 17, and the cathode end similar to the edge seal portions 14 and 18 of the separator main body 10. The separator body 10 is provided with four through-holes having substantially the same shape as the conductive member 20, although the holding part 33, the anode end holding part 37, and the edge seal parts 34 and 38 are provided. The separator body 30 is provided with two through holes having substantially the same shape as the conductive member 40.

The shaft portions 42 and 45 of the conductive member 40 pass through the intersection of the cathode end holding portion 33 and the anode end holding portion 37 and are sealed with an O-ring (not shown). Further, the flat plate portion 43 is disposed on the surface of the cathode end holding portion 33, and the flat plate portion 46 is disposed on the surface of the anode end holding portion 37. With such a configuration of the separator body 30 and the conductive member 40, in the present fuel cell, the pair of flat plates 43 is pressed against both ends of the cathode 4, and the pair of flat plates 46 are pressed against both ends of the anode 3. Will be
Good electrical connection between the cathode 4 and the anode 3 and the conductive member 40 can be performed.

Further, since the conductive member 40 is a combination of the first member 41 and the second member 44, the conductive member 40 can be easily fitted into the through hole of the separator body 30. [Modifications] The present invention has been described based on the first and second embodiments. However, it goes without saying that the contents of the present invention are not limited to the above-described embodiments. Conceivable.

(A) In the above-described embodiment, an example has been described in which the edge seal portion is formed to be higher than the anode end sandwiching portion and the cathode end sandwiching portion by the thickness of the anode and cathode in the separator body. The edge seal portion is formed at the same height as the anode end holding portion and the cathode end holding portion, and instead, a shim material corresponding to the thickness of the anode and the cathode is interposed between the edge seal portion and the electrolyte matrix. Is also good. As the material of the shim material, a material having heat resistance, elasticity and acid resistance at the operating temperature of the battery is preferable, and specific examples thereof include the expandable graphite mentioned as the material of the conductive member. .

(B) In the above embodiment, an example is shown in which the conductive member is pressed against the anode and the cathode and is electrically connected. However, a current collector is provided between the conductive member and the anode and the cathode. Even if it is interposed, it can be carried out similarly. (C) In the above embodiment, an example is shown in which gas channels are carved on the surface of the separator main body. However, the gas channels are not formed on the separator main body, and the substrate on which the gas channels are formed is separated from the separator main body. A fuel cell can also be configured by disposing on both sides and alternately stacking the unit cells.

Here, when both substrates provided on both surfaces of the separator body are conductive (for example, a substrate made of a material in which porous carbon is impregnated with phosphoric acid), the conductive material penetrating the separator body is used. If a member is interposed between the two substrates and the two substrates are electrically connected to each other, the electrical connection between adjacent unit cells is also made. (D) In the above embodiment, the example of the phosphoric acid type fuel cell is described, but the present invention can be similarly applied to a fuel cell such as a polymer electrolyte type or an alkaline type fuel cell.

(E) In the above embodiment, an example of a fuel cell provided with an external manifold is shown. However, the same applies to a fuel cell provided with an internal manifold on the outer periphery of a separator body. Can be. Further, if a material having excellent heat resistance such as ceramic is used for the separator body, it can be applied to a solid electrolyte fuel cell or a fuel cell of a type that operates at a high temperature such as a molten carbonic acid fuel cell.

[0038]

As described above, according to the present invention, a separator in a fuel cell is provided with a flat separator main body, a first separator body penetrating through the separator main body and exposed on one surface of the separator main body. A second current collector surface exposed to the other surface of the separator main body, and an anode of a cell existing on the first current collector surface side and a cathode of a single cell present on the second current collector surface side And a conductive member for electrically connecting the separator body, the function of conducting the unit cells adjacent to the separator is secured without using a conductive material for the separator body. And various other materials can be used.

In particular, if the separator main body is made of a resin having heat resistance at the operating temperature of the fuel cell, the mass of the separator main body can be easily mass-produced by a method such as injection molding and the cost can be reduced. Further, the present invention can be easily applied to a small fuel cell using a unit cell having a small area, and is highly useful.

[Brief description of the drawings]

FIG. 1 is an assembly diagram showing a configuration of a main part of a phosphoric acid fuel cell according to a first embodiment.

FIG. 2 is a perspective view showing an appearance of a conductive member 20 of FIG.

FIG. 3 is a sectional view taken along line XX of the fuel cell 1 shown in FIG.

FIG. 4 is an external perspective view of a conductive member 40 used in a second embodiment.

FIG. 5 is an exploded perspective view of a main part of FIG.

FIG. 6 is a plan view showing a state where two conductive members are fitted in a separator body according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Electrolyte matrix 3 Anode 4 Cathode 5 Unit cell 6 Separator plate 10 Separator main body 11, 15 Gas channel 12, 16 rib 13 Cathode end holding part 14, 18 Edge seal part 17 Anode end holding part 20 Conductive member 21 Shaft part DESCRIPTION OF SYMBOLS 22 Flat plate part 23 Tip part 24 O-ring 40 Conductive member 43,46 Flat plate part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kunihiro Nakato 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (6)

[Claims] 1. A fuel cell comprising a cell stack in which a unit cell in which an anode and a cathode are arranged via an electrolyte layer and a separator are alternately stacked, wherein at least one of the separators comprises a plate-shaped separator body and A first current collector surface that is provided through the separator body and is exposed on one surface of the separator body, and a second current collector surface that is exposed on the other surface of the separator body; A fuel cell, comprising: a conductive member that electrically connects an anode of a unit cell on a power supply surface side and a cathode of a unit cell on a second current collecting surface side. 2. The fuel cell according to claim 1, wherein the conductive member extends through a region of the separator body outside a region where a gas channel is formed. 3. An anode end holding portion for holding an end of an anode and a cathode end holding portion for holding an end of a cathode are formed on a surface of the separator main body. 3. The fuel cell according to claim 2, wherein the power supply surface is exposed to the anode end holding portion, and the second current collecting surface is exposed to the cathode end holding portion. 4. The conductive member includes: a shaft portion penetrating a separator body; a first planar current collector disposed on a surface of the anode end holding portion; and a surface of the cathode end holding portion. 4. The fuel cell according to claim 3, comprising a planar second current collector disposed. 5. The fuel cell according to claim 1, wherein the separator body is made of a resin having heat resistance at an operating temperature of the fuel cell. 6. The fuel cell according to claim 1, wherein the conductive member is made of one selected from graphitized carbon and copper.