JP2003331860A - Unit cell structure, fuel cell, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the structure of a fuel cell and increase the electric power. <P>SOLUTION: This fuel cell 100 contains a plurality of unit cells 101 each having a solid electrolyte membrane 114, and a fuel electrode 102 and an oxidizing agent electrode 108 facing through the solid electrolyte membrane 114; and a plurality of connecting members 284 electrically connecting adjacent two unit cells 101. The fuel electrodes 102 of a plurality of unit cells 102 are arranged on one side partitioned by a plurality of connecting members 284, and the oxidizing agent electrodes 108 of a plurality of unit cells 101 are arranged on the other side partitioned by a plurality of connecting members 284. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a unit cell structure,
The present invention relates to a fuel cell and a manufacturing method thereof.

[0002]

2. Description of the Related Art A fuel cell has a fuel electrode and an oxidant electrode,
It is composed of an electrolyte provided between them, and the fuel is supplied to the fuel electrode and the oxidant is supplied to the oxidant electrode to generate electricity by an electrochemical reaction. Hydrogen is generally used as the fuel, but in recent years, direct type fuel cells have been actively developed which directly use methanol, which is inexpensive and easy to handle, as the fuel.

When hydrogen is used as the fuel, the reaction at the fuel electrode is expressed by the following equation (1). 3H ₂ → 6H ⁺ + 6e ⁻ (1)

When methanol is used as the fuel, the reaction at the fuel electrode is expressed by the following equation (2). CH ₃ OH + H ₂ O → 6H ⁺ + CO ₂ + 6e ⁻ (2)

In any case, the reaction at the oxidant electrode is expressed by the following equation (3). 3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O (3)

Fuel cells are classified into many types according to the difference in electrolyte, but generally they are roughly classified into alkali type, solid polymer type, phosphoric acid type, molten carbonate type, and solid electrolyte type. . Among them, polymer electrolyte fuel cells have been attracting attention because they can obtain high output.

FIG. 7 is a perspective view showing a unit cell of a general polymer electrolyte fuel cell. The unit cell 261 of the solid polymer electrolyte fuel cell has a solid polymer electrolyte membrane 266 such as a perfluorosulfonic acid membrane, and a fuel electrode 262 and an oxidizer electrode 264 are bonded to both surfaces of this solid polymer electrolyte membrane 266. Consists of The fuel electrode 262 and the oxidant electrode 26
4 is composed of a mixture of a carbon material carrying a catalyst material and fine particles of a solid polymer electrolyte.

In the above structure, the fuel supplied to the fuel electrode 262 passes through the pores in the fuel electrode 262 to reach the catalyst substance, and the fuel is decomposed by the catalyst substance to obtain the above formula (1) or the formula (1). As shown in (2), hydrogen ions and electrons are generated. The hydrogen ions reach the oxidant electrode 264 through the solid polymer electrolyte membrane 266, and react with oxygen supplied to the oxidant electrode 264 and electrons flowing from an external circuit to generate water as shown in the above formula (3). Occurs. On the other hand, the electrons released from the fuel electrode 262 by the decomposition of the fuel are guided to the external circuit and flow into the oxidant electrode 264 from the external circuit. As a result, in the external circuit, from the fuel electrode 262 to the oxidizer electrode 264.
Electrons flow toward and electric power is taken out.

[0009]

However, since one unit cell 261 cannot obtain a practically sufficient electric power, a plurality of unit cells 261 are usually connected electrically in series or in parallel. A fuel cell having a stack structure is used. The unit cells 261 are electrically connected to each other via the separator 268. The separator 268 is a fuel electrode 262 when the unit cell 261 has a stack structure.
Also has the function of separating the fuel supplied to the oxidizer electrode 264 and the oxidizer such as oxygen supplied to the oxidizer electrode 264.

As described above, when a stack structure in which a plurality of unit cells are connected via a separator is used, there is a problem that the entire device becomes huge and heavy. Also,
It is necessary to provide a fuel supply path, an oxidant supply path, etc. in the separator, which results in a complicated structure. Therefore, since it is easily broken during the forming process, it is necessary to make the thickness to a certain extent, and further, the entire apparatus becomes huge and heavy. Further, in order to increase the output power, it is necessary to stack a large number of unit cells and it is necessary to supply fuel or the like from a plurality of supply ports, which causes a problem of inconvenience in handling.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell capable of securing necessary electric power while simplifying the structure. Another object of the present invention is to increase the reliability of the fuel cell and its manufacturing process. Another object of the present invention is to improve the stability of the fuel cell and its manufacturing process.

[0012]

According to the present invention, a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode which are opposed to each other with the solid electrolyte membrane interposed therebetween, and a plurality of unit cells are provided. A partition wall that separates the fuel electrode of the unit cell from the oxidant electrodes of the plurality of unit cells, and a partition wall formed to electrically connect the fuel electrode of one unit cell and the oxidant electrode of another unit cell, respectively. A fuel cell including a plurality of connecting members is provided.

According to this structure, the fuel electrodes of the plurality of unit cells and the oxidizer electrodes of the plurality of unit cells can be separated by the partition walls, so that the structure of the fuel cell can be simplified. Further, since the fuel may be supplied to one of the chambers separated by the partition wall and the oxidant may be supplied to the other chamber, the fuel cell can be easily handled. Further, here, the connecting member can connect the fuel electrode of one unit cell and the oxidant electrode of another unit cell in series. This makes it possible to increase the output power while simplifying the structure of the fuel cell.

In this fuel cell, the partition walls can be formed in a zigzag shape. By forming the partition walls into a bent shape such as a zigzag shape, many unit cells can be arranged in a limited space, and the fuel cell can be made compact. Further, by having such a shape, the partition wall can be configured to be stretchable.
Thereby, further space saving can be achieved.
Further, the shape of the fuel cell can be changed appropriately.

According to the present invention, a plurality of unit cells each having a solid electrolyte membrane, a fuel electrode and an oxidant electrode, which are opposed to each other with the solid electrolyte membrane sandwiched therebetween, are provided between two adjacent unit cells. A plurality of connecting members electrically connected to each other, the fuel electrodes of the plurality of unit cells are arranged on one side partitioned by the plurality of connecting members, and the oxidizer electrodes of the plurality of unit cells are arranged on the other side. Is provided, and a fuel cell is provided.

According to this structure, the fuel electrodes of the plurality of unit cells and the oxidant electrodes of the plurality of unit cells can be separated by the plurality of connecting members, so that the structure of the fuel cell can be simplified. . In this way, the fuel electrode and the oxidant electrode can be partitioned without using a separator, so that the weight and volume of the fuel cell can be reduced. Further, since the fuel may be supplied to one of the chambers divided by the plurality of connecting members and the oxidant may be supplied to the other chamber, the fuel cell can be easily handled. Furthermore, since the function of electrically connecting two adjacent unit cells and the function of separating the fuel electrode and the oxidant electrode of these unit cells are realized by the connecting member, the fuel cell can be made compact. be able to. In addition, since two adjacent unit cells are connected by individual connecting members, respectively, the number of unit cells included in the fuel cell can be increased or decreased as necessary, and a desired output power can be obtained. it can.

Here, the connecting member can connect two adjacent unit cells in series. This makes it possible to increase the output power while simplifying the structure of the fuel cell.

In this fuel cell, each connecting member is formed in a plate shape, and is joined to the fuel electrode of one unit cell on the surface of one end and to the oxidant electrode of another unit cell on the back surface of the other end. The fuel electrode and the oxidant electrode can be isolated and electrically connected to each other. According to this configuration, since two adjacent unit cells can be connected in series, the output power of the fuel cell can be increased. Further, since each connecting member is formed in a plate shape,
The fuel cell can be made compact.

In this fuel cell, a first opening is provided at one end of the connecting member, and a second opening is provided at the other end of the connecting member so that the fuel electrode of one unit cell is connected. It is possible to have a structure in which the first opening of the member is exposed to the back surface side, and the oxidizer electrodes of the other unit cells are exposed to the front surface side from the second opening of the connection member. According to this configuration, the peripheral regions of the first opening and the second opening are respectively joined to the unit cell, so that the joining force between the unit cell and the connecting member can be increased. Further, with this configuration, the structure of the fuel cell can be reinforced. These can improve the reliability and stability of the fuel cell.

In this fuel cell, the connecting member may have a bent portion between the region where the fuel electrode of one unit cell is joined and the region where the oxidant electrode of another unit cell is joined. Thus, by forming the connecting member into a bent shape, many unit cells can be arranged in a limited space, and the fuel cell can be made compact. Further, the connecting member can be made of a material whose bending angle of the bending portion can be adjusted. By doing so, it is possible to form a stack structure in which the plurality of unit cells can expand and contract in the stacking direction. Thereby, further space saving can be achieved. Further, the shape of the fuel cell can be changed appropriately. Further, due to the elasticity of the stack structure itself of the plurality of unit cells, the stack structure can be fixed in the housing to form the fuel chamber and the oxidant chamber.

In this fuel cell, the plurality of connecting members can be arranged in a zigzag pattern. By forming the plurality of connecting members into a bent shape such as a zigzag shape, many unit cells can be arranged in a limited space, and the fuel cell can be made compact. Also,
With such a shape, a plurality of unit cells can be configured to be expandable and contractable. A plurality of unit cells can have a stack structure that can expand and contract in the stacking direction. Thereby, further space saving can be achieved. Further, the shape of the fuel cell can be changed appropriately.

In this fuel cell, the connecting members can be formed in substantially the same shape, and can be composed of repeating units of unit cells and connecting members. By making the connecting members have substantially the same shape, the manufacturing of the fuel cell can be facilitated. Further, in each unit cell, the fuel electrode and the oxidant electrode can be made of the same material.
In this way, when forming a stack structure of a plurality of unit cells, it is not necessary to treat the fuel electrode and the oxidant electrode separately, so that the fuel cell can be manufactured more easily. In this case, the two electrodes provided facing each other with the solid electrolyte membrane of each unit cell interposed therebetween may be configured to be partitioned by the connection member.

In this fuel cell, the connecting member can be formed in substantially the same shape by being folded in half between one end and the other end, and the plurality of connecting members can be formed on one surface outside one connecting member and the other. Can be arranged as a repeating unit of a structure in which one outer surface of the connecting member faces, the other inner surface of the other connecting member faces one inner surface of the other connecting member, and each unit cell is Can be arranged between the facing surfaces of the connecting member. Since the connecting member has a folded shape, the fuel cell can be made compact.
Further, the fuel cell can be easily manufactured by making the connecting members have substantially the same shape.

In this fuel cell, each connecting member can be made of a conductive material. By configuring the connecting member with a conductive material, the connecting member performs the function of electrically connecting the two unit cells and the function of separating the fuel electrode and the oxidizer electrode between the two unit cells.
The structure of the fuel cell can be simplified. If each connecting member is made of a conductive material from the region where the fuel electrode of one unit cell is joined to the region where the oxidant electrode of another unit cell is joined, the other part is made of a conductive material. Need not be composed of The other part of the connection member can be formed by molding a material having elasticity, for example. Thereby, the fuel cell can be further reduced in weight.

According to the present invention, there is provided a method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidizer electrode formed on both surfaces thereof, each of which is formed in a plate shape. A plurality of connecting members that are electrically connected to each other between two adjacent unit cells, and a step of joining a fuel electrode of one unit cell and an oxidant electrode of another unit cell, and a step of joining A method of manufacturing a fuel cell is provided, which comprises repeatedly dividing a fuel electrode of a plurality of unit cells and an oxidant electrode of a plurality of unit cells.

In this fuel cell manufacturing method, the method further includes the step of preparing a plurality of connecting members having the first opening formed on one end side and the second opening formed on the other end side, and the step of joining. Is a step of preparing a plurality of connecting members having a first opening on one end side and a second opening on the other end side,
Joining the fuel electrode of one unit cell from the surface of one connecting member to expose the fuel electrode to the back side from the first opening of the connecting member; and connecting the oxidant electrode of another unit cell to one Bonding from the back surface of the member to expose the oxidizer electrode to the back surface side from the second opening of the connecting member.

According to the present invention, there is provided a method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode formed on both surfaces of the solid electrolyte membrane. A step of preparing a plurality of connecting members, and a plurality of connecting members, one outer surface of one connecting member and one outer surface of another connecting member face each other, and Arranging as a repeating unit of a structure in which one surface on the inside of another connecting member faces each other, and arranging a plurality of unit cells between the facing surfaces of the plurality of connecting members, and bonding to these connecting members. And a step of electrically connecting two adjacent unit cells with these connecting members, a method for manufacturing a fuel cell is provided.

According to the present invention, there is provided a method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode formed on both surfaces thereof, the method comprising a conductive material. And a step of preparing a plurality of plate-shaped connecting members in which the first and second openings are formed,
A step of joining one of the fuel electrode and the oxidizer of the unit cell from the front surface side of the connecting member to form a plurality of unit cell structures having a configuration exposed from the first opening to the back surface side; In the cell structure, one of the fuel electrode and the oxidant electrode of the unit cell of the other unit cell structure is joined from the back surface side of the connecting member of the one unit cell structure, and the other surface of the unit cell structure is connected to the front surface side from the second opening. And a step of connecting to each other so as to be exposed to the inside of the fuel cell.

According to the present invention, a unit cell having a solid electrolyte membrane and a fuel electrode and an oxidant electrode respectively formed on both surfaces of the solid electrolyte membrane, and a plate-shaped unit cell, and first and second openings are formed. The unit cell is configured such that either the fuel electrode or the oxidant is bonded from the front surface side of the connection member and exposed to the back surface side from the first opening. A featured unit cell structure is provided.

In this unit cell structure, the connecting member may have a bent portion between the first opening and the second opening. Here, the unit cell structure may have either a structure in which the unit cells are joined inside the connecting member or a structure in which the unit cells are joined outside the connecting member.

In this unit cell structure, the connecting member can be made of a conductive material.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG. 1 is a sectional view schematically showing a unit cell of a fuel cell according to an embodiment of the present invention. Here, only one of the plurality of unit cells 101 included in the fuel cell is schematically shown. The unit cell 101 includes a fuel electrode 102, an oxidant electrode 108, and a solid electrolyte membrane 114. Solid electrolyte membrane 114
Separates the fuel electrode 102 and the oxidizer electrode 108,
It has a role of moving hydrogen ions between the both. Therefore, the solid electrolyte membrane 114 is preferably a membrane having high hydrogen ion conductivity. Further, it is preferably chemically stable and has high mechanical strength.

As a material forming the solid electrolyte membrane 114, an organic polymer having a strong acid group such as a sulfone group or a phosphoric acid group and a polar group such as a weak acid group such as a carboxyl group is preferably used. As such an organic polymer, sulfonated poly (4-phenoxybenzoyl-1,4-phenylene), an aromatic condensed polymer such as an alkyl sulfonated polybenzimidazole; a sulfone group-containing perfluorocarbon (Nafion (manufactured by DuPont) ( Registered trademark),
Aciplex (Asahi Kasei Co., Ltd.); Perfluorocarbon containing carboxyl group (Flemion S film (Asahi Glass Co., Ltd.)
(Registered trademark)); and the like.

The fuel electrode 102 and the oxidant electrode 108 have a fuel electrode side catalyst layer 106 and an oxidant electrode side catalyst layer 112 containing carbon particles carrying a catalyst and fine particles of a solid electrolyte, respectively, on a substrate 104 and a substrate 110. Can be formed into The surfaces of the base 104 and the base 110 may be water repellent.

As the catalyst of the fuel electrode side catalyst layer 106, platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, cobalt, nickel, rhenium,
Lithium, lanthanum, strontium, yttrium,
Or these alloys etc. are illustrated. As the catalyst of the oxidant electrode side catalyst layer 112, the same catalyst as the fuel electrode side catalyst layer 106 can be used, and the above-exemplified substances can be used. The catalysts of the fuel electrode side catalyst layer 106 and the oxidant electrode side catalyst layer 112 may be the same or different.

Examples of the carbon particles supporting the catalyst include acetylene black (Denka Black (produced by Denki Kagaku) (registered trademark), XC72 (produced by Vulcan), etc.), Ketjenblack, carbon nanotube, carbon nanohorn and the like. It The particle size of the carbon particles is, for example, 0.01 to
The thickness is 0.1 μm, preferably 0.02 to 0.06 μm.

The fine particles of the solid electrolyte in the fuel electrode side catalyst layer 106 and the oxidant electrode side catalyst layer 112 may be the same or different. Here, for the fine particles of the solid electrolyte, the same material as the solid electrolyte membrane 114 can be used, but a material different from the solid electrolyte membrane 114 or a plurality of materials can also be used.

The base 104 and the base 110 of both the fuel electrode 102 and the oxidizer electrode 108 are carbon paper, carbon compact, carbon sintered body, sintered metal,
A porous substrate such as foam metal can be used. Also,
A water repellent such as polytetrafluoroethylene can be used for the water repellent treatment of the base 104 and the base 110.

As the fuel, methanol, ethanol,
Organic liquid fuels such as dimethyl ether, other alcohols, or liquid hydrocarbons such as cycloparaffin can be used. The organic liquid fuel can be an aqueous solution. It is also possible to use as the fuel hydrogen, methane, propane, butane, or natural and synthetic carbohydrates such as biomass gas. Air can be usually used as the oxidant, but oxygen gas may be supplied.

The manufacturing method of the unit cell 101 in the present invention is not particularly limited, but it can be manufactured, for example, as follows. First, a catalyst is supported on carbon particles by a generally used impregnation method. Next, the carbon particles supporting the catalyst and the fine particles of the solid electrolyte are dispersed in a solvent to form a paste, and then the substrate 1 is treated to be water repellent.
The fuel electrode 102 and the oxidant electrode 108 are obtained by applying 04 or 110 and drying.

Here, the particle size of the carbon particles is, for example, 0.
It is set to 01 to 0.1 μm. The particle size of the solid electrolyte particles is, for example, 0.05 to 1 μm. The carbon particles and the solid electrolyte particles are, for example, in a weight ratio of 2: 1 to
Used in the 40: 1 range. The weight ratio of water to solute in the paste is, for example, about 1: 2 to 10: 1. The particle size of the catalyst particles is, for example, 1 nm to 10 nm. The method of applying the paste to the substrate 104 or 110 is not particularly limited, but, for example, a method such as brush coating, spray coating, and screen printing method can be used. The paste is applied with a thickness of about 1 μm to 2 mm. After applying the paste, the paste is heated at a heating temperature and a heating time depending on the material used, and the fuel electrode 102 and the oxidant electrode 108 are produced. The heating temperature and the heating time are appropriately selected depending on the material used, but for example, the heating temperature can be 100 ° C. to 250 ° C. and the heating time can be 30 seconds to 30 minutes.

The solid electrolyte membrane 114 in the present invention can be manufactured by adopting an appropriate method depending on the material used. For example, when the solid electrolyte membrane 114 is composed of an organic polymer material, it is obtained by casting a liquid obtained by dissolving or dispersing the organic polymer material in a solvent onto a peelable sheet such as polytetrafluoroethylene and drying the liquid. be able to.

Solid electrolyte membrane 1 produced as described above
14 is sandwiched between the fuel electrode 102 and the oxidant electrode 108 and hot pressed to obtain a unit cell 101. At this time, the fuel electrode side catalyst layer 106 and the oxidant electrode side catalyst layer 112 are brought into contact with the solid electrolyte membrane 114. The conditions of the hot press are selected according to the material, but the solid electrolyte membrane 114
And fuel electrode side catalyst layer 106 and oxidant electrode side catalyst layer 112
When the fine particles of the solid electrolyte therein are composed of an organic polymer having a softening point or a glass transition, the temperature may be higher than the softening temperature or glass transition temperature of these organic polymers.
Specifically, for example, the temperature is 100 to 250 ° C., the pressure is 1
˜100 kgf / cm ² , and time 10 seconds to 300 seconds.

FIG. 2 is a diagram showing a fuel cell 100 including a stack structure of a plurality of unit cells 101 formed as described above. The fuel cell 100 includes a plurality of unit cells 10
It includes a stack structure in which 1 and the connection member 284 folded in half are alternately joined, and an oxidant chamber 288 and a fuel chamber 286 separated by a partition wall formed by this stack structure. The stack structure of the plurality of unit cells 101 includes a first unit cell structure 285a and a second unit cell structure 285b formed by joining one unit cell 101 to a connection member 284 that is folded in two. Can be configured. Each connecting member 284 has an oxidizer electrode 108 of one unit cell 101 and another unit cell 101.
Of the fuel electrode 102 is electrically connected.

Here, the unit cell 10 of each connecting member 284.
An opening is formed in a region where 1 is joined as described later, and in the plurality of unit cells 101, the oxidant electrode 108 is exposed on the oxidant chamber 288 side and the fuel electrode 102 is exposed on the fuel chamber 286 side. In this way, each is joined to the connecting member 284.
The oxidant 126 is supplied to the oxidant chamber 288, and the fuel 124 is supplied to the fuel chamber 286. Here, the fuel chamber 286 is preferably a closed space, but the oxidant chamber 288 can be an open space. The fuel chamber 286 and the oxidant chamber 288 may be configured so that the oxidant is not supplied to the fuel chamber 286 and the fuel is not supplied to the oxidant chamber 288.

In the present embodiment, the fuel chamber 286 and the oxidant chamber 288 are separated by the partition wall having the stack structure, so that the structure of the fuel cell 100 can be simplified. Further, since it is not necessary to use a separator, the fuel cell 100 can be made compact and lightweight. Further, the fuel electrodes 102 of the plurality of unit cells 101 are exposed in the fuel chamber 286, and the plurality of unit cells 10 are
Since the first oxidant electrode 108 is exposed to the oxidant chamber 288, the fuel 124 and the oxidant 126 can be easily supplied, and the fuel cell can be easily handled. As a result, the reliability and stability of the fuel cell can be improved.

FIG. 3 is a process chart showing a method of manufacturing the first unit cell structure 285a and the second unit cell structure 285b shown in FIG. As shown in FIG. 3A, the connecting member 284 is formed with a first opening 289a and a second opening 289b. The first opening 289a and the second opening 289b are formed smaller than the oxidant electrode 108 and the fuel electrode 102 of the unit cell 101.
Thereby, when the unit cell 101 is joined to the connecting member 284, the first opening 289a is formed by the unit cell 101.
The second opening 289b can be closed and a partition can be formed. On the other hand, from the viewpoint of improving the output of the unit cell 101, the first opening 289a and the second opening 289b are preferably formed as large as possible.

The connecting member 284 is made of a conductive material such as a metal material or a carbon material. Accordingly, when the two unit cells 101 are joined to the single connecting member 284, the unit cells 101 can be electrically connected to each other.

Next, as shown in FIG. 3B, the connecting member 284 is folded in two between the region in which the first opening 289a is formed and the region in which the second opening 289b is formed. To

Thereafter, as shown in FIGS. 3 (c) and 3 (d), the first unit cell structure 285a in which the unit cell 101 is joined to the outside of the half-fold and the unit cell 101 to the inside of the half-fold. The joined second unit cell structure 285b is formed. Here, the oxidizer electrode 108 of the unit cell 101
Each side is joined to the connecting member 284.

Returning to FIG. 2, the first unit cell structure 285a and the second unit cell structure 2 formed as described above.
85b are arranged alternately. The fuel cell 100 includes three first unit cell structures 285a and two second unit cell structures 285b. At this time, the first unit cell structure 2 arranged at the end of the stack structure of the unit cell 101.
Only the first opening 289a is formed in the connecting member 284 of 85a. A connecting member 284 having only the second opening 289b is connected to the end of the unit cell 101 opposite to the stack structure.

In the present embodiment, each unit cell 101
Of the oxidizer electrode 108 of the first opening 2 of each connecting member 284.
89a is joined to the connecting member 284, and the fuel electrode 102 of each unit cell 101 is joined to the connecting member 284 so as to cover the second opening 289b of each connecting member 284. Can be formed so as to be exposed on the surface. Further, since each connecting member 284 electrically connects the fuel electrode 102 of one unit cell 101 and the oxidant electrode 108 of another unit cell 101, these unit cells 101 can be connected in series. it can.

According to this embodiment, the unit cell 101 is formed by the repeating unit of the connecting member 284 and the unit cell 101.
Since the stack structure can be formed, the manufacturing of the fuel cell 100 can be facilitated. Further, by increasing or decreasing the number of unit cells 101 included in the stack structure, desired output power can be obtained. In addition, each connecting member 284 is folded in two and a plurality of connecting members 284 are
Are arranged in a zigzag pattern, the plurality of unit cells 101
Can be a stack structure that can be expanded and contracted into a laminated structure. Thereby, further space saving can be achieved.

The stack structure of the plurality of unit cells 101 is not limited to the form described above, and can be formed by various methods. For example, a plurality of connecting members 284 and a plurality of unit cells 101 may be sequentially joined and formed without manufacturing the first unit cell structure 285a and the second unit cell structure 285b.

The first unit cell structure 285a and the second unit cell structure 285b are not limited to the manufacturing method shown in FIG. 3 and can be manufactured by other methods.
For example, the connection member 284 may be folded in two after the unit cell 101 is joined to the connection member 284.

In the above description, the connection member 284 is made of a conductive material, but each connection member 284 is formed.
Is made of a conductive material from the region where the oxidant electrode 108 of one unit cell 101 is joined to the region where the fuel electrode 102 of another unit cell 101 is joined, the other part is made conductive. It need not be composed of materials. The other part of the connecting member 284 may be formed by molding an elastic material, for example.

Furthermore, the first opening 2 of the connecting member 284
89a and the second opening 289b are not limited to the holes having the shapes shown in FIGS. 3A and 3B, and the connecting member 284 includes the first opening 289a and the second opening 289b. It suffices that the connecting region with the unit cell 101 is formed in the peripheral region of the portion 289b, and for example, the connecting member 284 may have a notch formed from one end or the other end. This can increase the bonding force between the unit cell 101 and the connecting member 284.

In the above description, the fuel electrode 102 and the oxidizer electrode 108 are distinguished from each other, but the fuel electrode 102 is different.
When the oxidizer electrode 108 and the oxidant electrode 108 are made of the same material, the fuel electrode 102 is not formed in the manufacturing process of the fuel cell 100.
It is not necessary to distinguish between and the oxidizer electrode 108. In this case, it is sufficient that one electrode and the other electrode of each unit cell 101 are separated by a partition wall having a stack structure, and the electrode exposed on the fuel chamber 286 side is the fuel electrode 102 and the oxidation electrode. The electrode exposed on the side of the agent chamber 288 is defined as the oxidant electrode 108.

(Second Embodiment) FIG. 4 is a diagram showing a stack structure of unit cells included in a fuel cell according to a second embodiment. In the present embodiment, the same components as those in the first embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In this embodiment, the shape of the connecting member 284 is different from that of the first embodiment.

As shown in FIG. 4, each connecting member 284 is
It can be formed in a substantially U-shape that is curved at the central portion. Also in this embodiment, an opening is formed in a region of the connection member 284 where the unit cell 101 is joined. Even with such a shape, this stack structure can be expanded and contracted in the stacking direction of the plurality of unit cells 101, and the plurality of unit cells 101 can be connected in series in a compact shape. In addition, since the unit cells 101 and the connecting members 284 can be formed by repeating units, a desired number of unit cells 101 can be formed in a stack structure. As described above, in this embodiment, the same advantages as those of the first embodiment can be obtained.

(Third Embodiment) FIG. 5 is a diagram showing a stack structure of unit cells included in a fuel cell according to a third embodiment. In the present embodiment, the same components as those in the first embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In this embodiment, the shape of the connecting member 284 is different from that of the first embodiment.

As shown in this figure, each connecting member 284
Can be formed in a substantially N shape. Also in this embodiment, an opening is formed in a region of the connection member 284 where the unit cell 101 is joined. Even with such a shape, this stack structure can be expanded and contracted in the stacking direction of the plurality of unit cells 101, and the plurality of unit cells 101 can be connected in series in a compact shape. In addition, since the unit cells 101 and the connecting members 284 can be formed by repeating units, a desired number of unit cells 101 can be formed in a stack structure. As described above, also in the present embodiment, the same advantages as those of the first embodiment can be obtained.

(Fourth Embodiment) FIG. 6 is a diagram showing a stack structure of unit cells included in a fuel cell according to a fourth embodiment. Also in this embodiment, an opening is formed in a region of the connection member 284 where the unit cell 101 is joined. 6 (a), 6 (b) and 6
As shown in (c), the connecting member 284 electrically connects one fuel electrode and the other oxidant electrode of two adjacent unit cells 101, and connects these fuel electrode and oxidant electrode. It may have any shape as long as it can be spatially isolated. Even with such a shape, since the fuel chamber 286 and the oxidant chamber 288 shown in FIG. 2 are separated by the partition wall having the stack structure, the structure of the fuel cell 100 can be simplified. Further, the fuel cell 100 can be made compact and lightweight. Furthermore, handling of the fuel cell 100 can be facilitated. As a result, the reliability and stability of the fuel cell 100 can be improved. However, the stack shown in the first to third embodiments is that the stack structure of the plurality of unit cells 101 can be expanded and contracted in the stacking direction and further space saving can be achieved. The structure is more preferable.

[0064]

EXAMPLES The fuel cell of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 The fuel cell of this example was manufactured as follows. Nafion 117 (manufactured by DuPont) was used as the solid electrolyte membrane. Both the fuel electrode and the oxidizer electrode have Denka black (produced by Denki Kagaku) as carbon particles, a 1: 1 alloy of platinum and ruthenium as a catalyst,
A 5% Nafion alcohol solution (manufactured by Aldrich Chemical Co.) was used as fine particles of the solid electrolyte. The weight ratio of the catalyst alloy to the elementary particles was 1: 1. As the substrate, carbon paper (TGP-H-120 manufactured by Toray Industries, Inc.) was used for both the fuel electrode and the oxidizer electrode.

First, a 5% Nafion alcohol solution 18
1 ml of catalyst-supported Denka Black was mixed with ml,
An ultrasonic disperser was applied at 50 ° C. for about 3 hours to form a paste. This paste-like sample of Nafion 117 was applied to carbon paper by screen printing at 2 mg / cm ² and then dried at 120 ° C. to obtain a fuel electrode and an oxidizer electrode. These fuel electrode and oxidizer electrode are attached to Nafion 117
A unit cell was formed by hot-pressing both surfaces at 120 ° C.

Subsequently, the unit cells thus formed were attached one by one so as to cover one opening of the connecting member having the two openings. At this time, as the connecting member arranged at the end of the stack structure, one having only one opening was used. Subsequently, the connecting member is folded in two between the two openings, and a first unit cell structure in which unit cells are joined to the outside and a second unit cell structure in which unit cells are joined to the inside Was formed. Thus, three first unit cell structures and two second unit cell structures were prepared, and these unit cell structures were arranged so as to be alternately arranged. A connecting member having only one opening was joined to the opposite end of the stack structure. As a result, a stack structure of five unit cells 101 similar to that shown in FIG. 2 was obtained. The stack structure is
The thickness in the stacking direction was 1 cm, and the cross-sectional area was 15 cm ² .

With this stack structure, the fuel chamber and the oxidant chamber were separated to form a fuel cell. The inside of the fuel chamber of this fuel cell was filled with a 10% aqueous methanol solution, and then the piezoelectric pump was used to supply and discharge the 10% aqueous methanol solution at 2 ml / min. When the cell characteristics were measured by exposing the outside of the fuel cell to the atmosphere, the current density was 100 mA.
The battery voltage at the time of / cm ² was 1.8V. This corresponds to a voltage five times as high as that when measured with the unit cell alone, and series connection was confirmed.

Example 2 When the fuel was changed to hydrogen gas and the cell characteristics were measured, the current density was 600 mA / cm ^2.
The battery voltage at that time was 3.0 V, which was 5 times the battery voltage of 600 mV measured with the unit cell alone.

The present invention has been described above based on the embodiments and examples. It should be understood by those skilled in the art that the embodiments and examples are mere examples, and that various modifications can be made to the combination of each constituent element and each process, and such modifications are also within the scope of the present invention. This is where Hereinafter, such an example will be described.

In the above-mentioned embodiments and examples, it has been described that the partition wall is formed by the stack structure in which the plurality of connecting members and the plurality of unit cells are alternately joined. It can also be configured by one solid electrolyte membrane provided commonly to the cells. In this case, the solid electrolyte membrane can be formed in a zigzag shape. At this time, between two adjacent unit cells,
For example, a through hole is formed in the solid electrolyte membrane and electrically connected in series by some connecting means such as passing a conductive material inside. With this configuration, the structure of the fuel cell can be simplified and the output power of the fuel cell can be improved. Moreover, since the solid electrolyte membrane is formed in a zigzag shape, the fuel cell can be made compact.

[0072]

As described above, according to the present invention, required electric power can be obtained while simplifying the structure of the fuel cell. Further, according to the present invention, the reliability and stability of the fuel cell and its manufacturing process can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a unit cell of a fuel cell according to a first embodiment of the present invention.

FIG. 2 is a view showing a fuel cell including the unit cell stack structure shown in FIG.

FIG. 3 is a process drawing showing the method of manufacturing the unit cell structure shown in FIG.

FIG. 4 is a diagram showing a unit cell stack structure of a fuel cell according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a unit cell stack structure of a fuel cell according to a third embodiment of the present invention.

FIG. 6 is a view showing a stack structure of unit cells of a fuel cell according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a unit cell of a conventional, general polymer electrolyte fuel cell.

[Explanation of symbols]

100 fuel cell 101 unit cell 102 fuel pole 104 substrate 106 fuel electrode side catalyst layer 108 Oxidizer pole 110 base 112 Oxidizer electrode side catalyst layer 114 Solid electrolyte membrane 124 fuel 126 Oxidizing agent 284 connection member 285a First unit cell structure 285b Second unit cell structure 286 Fuel chamber 288 Oxidizer chamber 289a First opening 289b Second opening

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuyoshi Yoshitake             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Shin Nakamura             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Hidekazu Kimura             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Hideto Imai             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Yoshimi Kubo             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Yuichi Shimakawa             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company F-term (reference) 5H026 AA06 CV03

Claims (17)

[Claims] 1. A plurality of unit cells each having a solid electrolyte membrane, and a fuel electrode and an oxidant electrode that are opposed to each other with the solid electrolyte membrane interposed therebetween, and the fuel electrodes of the plurality of unit cells and the unit electrode. A partition wall that separates the oxidant electrodes of a plurality of unit cells, and the partition wall is formed on the partition wall and electrically connects the fuel electrode of one unit cell and the oxidant electrode of another unit cell, respectively. A fuel cell comprising: a plurality of connecting members; 2. The fuel cell according to claim 1, wherein the partition wall is formed in a zigzag shape. 3. A plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode which are provided so as to face each other with the solid electrolyte membrane interposed therebetween, and an electric field is provided between two adjacent unit cells. A plurality of connecting members that are connected to each other, the fuel electrodes of the plurality of unit cells are arranged on one side partitioned by the plurality of connecting members, and the fuel cells of the plurality of unit cells on the other side. A fuel cell having an oxidizer electrode. 4. The fuel cell according to claim 3, wherein each of the connecting members is formed in a plate shape, and the surface of one end is
One of the unit cells is joined to the fuel electrode, and the other end of the unit cell is joined to the oxidant electrode of the other unit cell to isolate the fuel electrode and the oxidant electrode from each other and electrically. A fuel cell characterized by being connected. 5. The fuel cell according to claim 4, wherein a first opening is provided at the one end side of the connecting member,
A second opening is provided on the other end side of the connecting member, the fuel electrode of the one unit cell is exposed to the back surface side from the first opening of the connecting member, and The fuel cell, wherein the oxidizer electrode of the unit cell is exposed to the surface side from the second opening of the connecting member. 6. The fuel cell according to claim 3, wherein the connecting member is a region where the fuel electrode of the one unit cell is joined and the oxidant electrode of the other unit cell. A fuel cell, characterized in that it has a bent portion between it and a region where is joined. 7. The fuel cell according to claim 3, wherein the plurality of connecting members are arranged in a zigzag pattern. 8. The fuel cell according to claim 3, wherein the connecting member is formed in substantially the same shape, and is composed of repeating units of the unit cell and the connecting member. Fuel cell to do. 9. The fuel cell according to claim 3, wherein the connecting member is formed in a substantially identical shape that is folded in two between the one end and the other end. In the member, one outer surface of the one connecting member faces one outer surface of the other connecting member, and one inner surface of the other connecting member faces one inner surface of the other connecting member. A fuel cell, wherein the fuel cell is arranged as a repeating unit of a structure, and each of the unit cells is arranged between the facing surfaces of the connecting members. 10. The fuel cell according to claim 3, wherein each of the connecting members is made of a conductive material. 11. A method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode formed on both surfaces thereof, the method comprising: A step of electrically connecting two adjacent unit cells with a connecting member and joining the fuel electrode of one unit cell to the oxidant electrode of another unit cell; and Repeating the steps to partition the fuel electrodes of the plurality of unit cells from the oxidant electrodes of the plurality of unit cells. 12. The method of manufacturing a fuel cell according to claim 11, wherein a step of preparing a plurality of connecting members having a first opening formed at one end and a second opening formed at the other end Further comprising the step of joining, the one fuel cell of the unit cell is joined from the front surface of the one connecting member to the fuel electrode from the first opening of the connecting member to the back surface side. And a step of exposing the oxidizer electrode of another unit cell from the back surface of the one connecting member to expose the oxidizer electrode to the back surface side from the second opening of the connecting member. A method of manufacturing a fuel cell, comprising: 13. A method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidant electrode formed on both surfaces thereof, the method comprising a plate-like folded connection. A step of preparing a plurality of members, the plurality of connecting members, one outer surface of the one connecting member and one outer surface of the other connecting member face each other, and the other inner surface of the other connecting member Disposing as a repeating unit of a structure in which one inner surface of the other connecting member faces each other, and disposing the plurality of unit cells between the facing surfaces of the plurality of connecting members, to these connecting members. And a step of electrically connecting two unit cells that are adjacent to each other and that are adjacent to each other by these connecting members. 14. A method for producing a fuel cell including a plurality of unit cells each having a solid electrolyte membrane and a fuel electrode and an oxidizer electrode formed on both surfaces thereof, the method comprising: And a step of preparing a plurality of plate-shaped connecting member formed with a second opening, and by joining one of the fuel electrode and the oxidizer of the unit cell from the surface side of the connecting member, the first A step of forming a plurality of unit cell structures having a structure exposed to the back surface side from one opening, and a plurality of the unit cell structures from the back surface side of the connecting member of the one unit cell structure Or the other of the fuel electrode and the oxidant electrode of the unit cell of the unit cell structure is joined and connected to each other so as to be exposed from the second opening to the surface side. Characterized by Manufacturing method of a fuel cell. 15. A unit cell having a solid electrolyte membrane, a fuel electrode and an oxidizer electrode formed on both surfaces thereof, and a connecting member formed in a plate shape and having first and second openings. The unit cell is configured such that one of the fuel electrode and the oxidant is joined from the front surface side of the connection member, and is exposed from the first opening to the back surface side. A unit cell structure characterized by the following. 16. The unit cell structure according to claim 15, wherein the connecting member has a bent portion between the first opening and the second opening. body. 17. The unit cell structure according to claim 15, wherein the connecting member is made of a conductive material.