WO2013114800A1

WO2013114800A1 - Fuel cell and fuel cell system

Info

Publication number: WO2013114800A1
Application number: PCT/JP2013/000186
Authority: WO
Inventors: 博晶鈴木; 安尾　耕司
Original assignee: 三洋電機株式会社
Priority date: 2012-01-31
Filing date: 2013-01-17
Publication date: 2013-08-08
Also published as: JP2015079562A

Abstract

A fuel cell (10) is provided with: a film electrode bonded body (100), which is configured of an electrolyte film (102), a cathode catalyst layer (104), which is provided on one surface of the electrolyte film (102), and an anode catalyst layer (106), which is provided on the other surface of the electrolyte film (102); and a water channel (128), which is configured of a material different from that of the electrolyte film (102), connects the cathode catalyst layer (104), and an anode catalyst layer neighborhood region (102a) of the electrolyte film (102) to each other, and permits water contained in the cathode catalyst layer (104) to move to the anode catalyst layer neighborhood region (102a).

Description

Fuel cell and fuel cell system

The present invention relates to a fuel cell and a fuel cell system.

A fuel cell is a device that generates electrical energy from hydrogen and oxygen, and can achieve high power generation efficiency. The main features of the fuel cell are direct power generation that does not go through the process of thermal energy or kinetic energy as in the conventional power generation method, so high power generation efficiency can be expected even on a small scale, and emissions of nitrogen compounds, etc. There are few, and noise and vibration are also small, and environmental properties are good. In this way, fuel cells can be used effectively for the chemical energy of fuel and have environmentally friendly characteristics, so they are expected as energy supply systems for the 21st century, and are widely used in space, automobiles and portable devices. It is attracting attention as a promising new power generation system that can be used for various applications from scale power generation to small-scale power generation, and technological development is in full swing toward practical use.

Patent Document 1 discloses a solid polymer type comprising a plurality of membrane electrode assemblies (cells) arranged in a plane and an interconnector that connects one anode and the other cathode of adjacent membrane electrode assemblies. A fuel cell is disclosed. Patent Document 2 discloses a fuel cell including a cell stack in which a plurality of cells are arranged in a plane, and a mesh-shaped condensed water retaining material arranged on the cathode side of the cell stack. Further, Patent Document 3 discloses a fuel cell including a plurality of planarly arranged cell units and a water reservoir formed by protruding an electrolyte membrane to the anode side between the cell units. . Further, Patent Document 4 includes an electrode non-formation region including a thin film region having a thickness smaller than that of the electrode formation region without a cathode provided on the surface, and an electrode formation region having a cathode provided on the surface. A fuel cell with an electrolyte membrane is disclosed.

JP 2003-197225 A International Publication No. 2007/105458 Pamphlet JP2008-243696 JP 2008-258142 A

In the above-described membrane / electrode assembly of a polymer electrolyte fuel cell, for example, hydrogen as fuel is supplied to the anode and oxygen as oxidant is supplied to the cathode to generate electromotive force and generate electric power. At that time, water is generated as a product at the cathode. Here, the reaction in the anode catalyst layer and the cathode catalyst layer is as follows.
Anode catalyst layer: H ₂ → 2H ⁺ + 2e ⁻
Cathode catalyst layer: 2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O

In the membrane electrode assembly, the electrolyte membrane sandwiched between the anode and the cathode functions as an ion exchange membrane that moves protons between the anode catalyst layer and the cathode catalyst layer. Generally, as the material constituting the electrolyte membrane, a material that exhibits good ion conductivity in a wet state is used. Also, the cathode catalyst layer and the anode catalyst layer may contain an ion exchange resin of the same material as the electrolyte membrane in order to realize good proton transmission between the electrolyte membrane and the catalyst particles. Therefore, it is desirable that the electrolyte membrane, the anode catalyst layer, and the cathode catalyst layer be maintained in a wet state. When the electrolyte membrane, the anode catalyst layer, and the cathode catalyst layer are dried, so-called dry-out occurs, and the power generation performance of the fuel cell decreases.

Here, when protons are transferred from the anode catalyst layer to the cathode catalyst layer, water in the vicinity of the anode catalyst layer and the anode catalyst layer of the electrolyte membrane also moves to the cathode catalyst layer side together with the proton (electrochemical permeation). Therefore, the anode catalyst layer and the region near the anode catalyst layer of the electrolyte membrane were easier to dry than the cathode catalyst layer and the region near the cathode catalyst layer of the electrolyte membrane. In the cathode catalyst layer, water is generated by an electrochemical reaction, and a part of the water moves to the anode side through the reverse diffusion, so that the anode side can be somewhat humidified. However, in order to further improve the power generation performance of the fuel cell, there has been room for improvement in the suppression of drying on the anode side. In the fuel cell of Patent Document 2 described above, since water generated at the cathode is absorbed and retained by the dew condensation water retaining material, drying on the cathode side of the membrane electrode assembly can be suppressed. Inhibition of drying was insufficient. Further, in the fuel cells of Patent Documents 3 and 4, water generated on the cathode side is stored in a moisture storage portion or groove portion formed of an electrolyte membrane, and this water is used for humidification on the anode side. Therefore, until the water is accumulated in the moisture storage portion or the groove portion, the anode side drying suppression effect cannot be obtained, and there is room for improvement in terms of responsiveness that it is desired to quickly suppress the anode side drying.

The present invention has been made in view of these problems, and an object thereof is to provide a technique for improving the power generation performance of a fuel cell.

One aspect of the present invention is a fuel cell. The fuel cell includes an electrolyte membrane, a membrane electrode assembly composed of an electrolyte membrane, a cathode catalyst layer provided on one surface of the electrolyte membrane, and an anode catalyst layer provided on the other surface of the electrolyte membrane. Comprising a water channel portion made of different materials, connecting the cathode catalyst layer and the region near the anode catalyst layer of the electrolyte membrane, and allowing water contained in the cathode catalyst layer to move to the region near the anode catalyst layer. Features.

According to the present invention, the power generation performance of the fuel cell can be improved.

1 is a perspective view showing an appearance of a fuel cell according to Embodiment 1. FIG. FIG. 2A is a schematic cross-sectional view along the line AA in FIG. FIG. 2B is a plan view showing a schematic structure of the membrane electrode assembly and the connection part of the fuel cell according to Embodiment 1. FIG. FIG. 3 is an enlarged view of a region B surrounded by a broken line in FIG. 4 (A) to 4 (C) are process diagrams showing a method for manufacturing a fuel cell according to Embodiment 1. FIG. 5 (A) to 5 (C) are process diagrams showing a method for manufacturing a fuel cell according to Embodiment 1. FIG. 6 (A) and 6 (B) are process charts showing the fuel cell manufacturing method according to Embodiment 1. FIG. 6 is a cross-sectional view partially showing a schematic structure of a fuel cell according to Embodiment 2. FIG. 8A to 8D are process diagrams showing a method for manufacturing a fuel cell according to the second embodiment. FIG. 9A is a perspective view of the fuel cell system according to Embodiment 3 as viewed obliquely from above. FIG. 9B is a perspective view of the fuel cell system according to Embodiment 3 as viewed obliquely from below. FIG. 10A is a front view showing a schematic structure inside the housing of the fuel cell system according to Embodiment 3. FIG. FIG. 10B is a perspective view showing a schematic structure inside the housing of the fuel cell system according to the third embodiment. FIG. 11A is an enlarged plan view of the reinforcing portion. FIG. 11B is a schematic cross-sectional view along the line EE in FIG. FIG. 11C is a schematic cross-sectional view along the line FF in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

(Embodiment 1)
FIG. 1 is a perspective view showing an appearance of a fuel cell according to Embodiment 1. FIG. FIG. 2A is a schematic cross-sectional view along the line AA in FIG. FIG. 2B is a plan view showing a schematic structure of the membrane electrode assembly and the connection part of the fuel cell according to Embodiment 1. FIG. FIG. 3 is an enlarged view of a region B surrounded by a broken line in FIG. In FIG. 2B, the cathode catalyst layer 104 is indicated by a broken line, and the cathode catalyst layer 104 is seen through.

The fuel cell 10 according to the present embodiment includes a plurality of membrane electrode assemblies (cells) 100, a connection portion 120, a cathode housing 12, and an anode housing 14. In addition, although the fuel cell 10 of the present embodiment includes the five membrane electrode assemblies 100, the number of the membrane electrode assemblies 100 is not particularly limited, and may be one or more than five.

Each membrane electrode assembly 100 includes an electrolyte membrane 102, a cathode catalyst layer 104 provided on one surface of the electrolyte membrane 102, and an anode catalyst layer 106 provided on the other surface of the electrolyte membrane 102. A cell is configured by sandwiching the electrolyte membrane 102 between the cathode catalyst layer 104 and the anode catalyst layer 106. For example, air as an oxidant is supplied to the cathode catalyst layer 104, and hydrogen as a fuel gas is supplied to the anode catalyst layer 106. The cell generates electricity by an electrochemical reaction between hydrogen and oxygen in the air.

The electrolyte membrane 102 preferably exhibits good ionic conductivity in a wet state, and functions as an ion exchange membrane that moves protons between the anode catalyst layer 106 and the cathode catalyst layer 104. The electrolyte membrane 102 is formed of a solid polymer material such as a fluorine-containing polymer or a non-fluorine polymer, and for example, a sulfonic acid type perfluorocarbon polymer, a polysulfone resin, a perfluorocarbon polymer having a phosphonic acid group or a carboxylic acid group. Etc. can be used. Examples of the sulfonic acid type perfluorocarbon polymer include Nafion (manufactured by DuPont: registered trademark) 112. Examples of non-fluorine polymers include sulfonated aromatic polyetheretherketone and polysulfone. The thickness of the electrolyte membrane 102 is, for example, 10 to 200 μm.

The cathode catalyst layer 104 and the anode catalyst layer 106 have ion-exchange resin and catalyst particles, and possibly carbon particles, respectively. The ion exchange resin included in the cathode catalyst layer 104 and the anode catalyst layer 106 connects the catalyst particles and the electrolyte membrane 102 and has a role of transmitting protons therebetween. This ion exchange resin can be formed of the same polymer material as the electrolyte membrane 102. Examples of catalyst metals include Sc, Y, Ti, Zr, V, Nb, Fe, Co, Ni, Ru, Rh, Pd, Pt, Os, Ir, alloys selected from lanthanoid series elements and actinoid series elements, A simple substance is mentioned. When the catalyst is supported, acetylene black, ketjen black, carbon nanotubes or the like may be used as the carbon particles. The thickness of the cathode catalyst layer 104 and the anode catalyst layer 106 is, for example, 10 to 40 μm.

The plurality of membrane electrode assemblies 100 are arranged in a plane. A connecting portion 120 is disposed between adjacent membrane electrode assemblies 100, and adjacent membrane electrode assemblies 100 are electrically connected via an interconnector 122 of the connecting portion 120. In the two outermost

membrane electrode assemblies

100a and 100b, the anode catalyst layer 106 of one membrane electrode assembly 100a and the cathode catalyst layer 104 of the other membrane electrode assembly 100b are respectively current collectors. (Not shown) is connected. The plurality of membrane electrode assemblies 100 can also have a stacked structure or the like. Further, although the fuel cell 10 of the present embodiment has a module structure having a plurality of cells, the fuel cell 10 may be a single cell.

The connecting portion 120 includes an interconnector 122, a first insulating layer 124, a second insulating layer 126, a water channel portion 128, a waterproof portion 130, and a gas seal portion 132. Hereinafter, the connecting portion 120 will be described in detail with reference to FIG. 3, taking the connecting portion 120 a disposed between the membrane electrode assembly 100 b and the membrane electrode assembly 100 c as an example. In the fuel cell 10 of the present embodiment, the plurality of membrane electrode assemblies 100 and the plurality of water channel portions 128 correspond one-to-one, and each water channel portion 128 corresponds to the cathode catalyst in the corresponding membrane electrode assembly 100. Water transfer from the layer 104 to the anode catalyst layer vicinity region 102a is enabled. In FIG. 3, the membrane electrode assembly 100b corresponds to the water channel portion 128 of the outer connection portion 140, and the membrane electrode assembly 100c corresponds to the water channel portion 128 of the connection portion 120a.

The interconnector 122 is made of a conductive material. Examples of the conductive material include carbon materials such as carbon fiber, graphite sheet, carbon paper, and carbon powder, and metal materials such as platinum, gold, stainless steel, titanium, and nickel. Further, the interconnector 122 has gas impermeability. Since the interconnector 122 has gas impermeability, the occurrence of cross leaks via the interconnector 122 can be suppressed. The anode catalyst layer 106 of the membrane electrode assembly 100b is connected to one end (the lower end in FIG. 3) of the interconnector 122 of the connecting portion 120a. The cathode catalyst layer 104 of the membrane electrode assembly 100c is connected to the other end (the upper end in FIG. 3) of the interconnector 122 of the connecting portion 120a. Thereby, the anode catalyst layer 106 of the membrane electrode assembly 100b and the cathode catalyst layer 104 of the membrane electrode assembly 100c are electrically connected. The cathode catalyst layer 104 and the anode catalyst layer 106 may be connected to the interconnector 122 via current collectors (not shown).

A first insulating layer 124 is interposed between the membrane electrode assembly 100 b and the interconnector 122. A second insulating layer 126 is interposed between the membrane electrode assembly 100 c and the interconnector 122. The first insulating layer 124 and the second insulating layer 126 are made of an insulating material such as a general plastic resin such as phenol resin, vinyl resin, polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, urea resin, and fluorine resin. It is formed. The first insulating layer 124 and the second insulating layer 126 have gas impermeability and waterproofness. Since the first insulating layer 124 and the second insulating layer 126 are gas-impermeable, occurrence of cross leak through the first insulating layer 124 and the second insulating layer 126 can be suppressed. Further, since the first insulating layer 124 is waterproof, it is possible to suppress water in the electrolyte membrane 102 from leaking to the interconnector 122 side through the first insulating layer 124. Moreover, since the 2nd insulating layer 126 has waterproofness, it can suppress that the water in the water channel part 128 leaks out to the interconnector 122 side via the 2nd insulating layer 126.

In the present embodiment, the anode catalyst layer 106 of the membrane electrode assembly 100b extends beyond the first insulating layer 124 to the interconnector 122 of the connecting portion 120a on the lower surface side of the membrane electrode assembly 100b, and is connected to the interconnector 122. In contact. Further, the cathode catalyst layer 104 of the membrane electrode assembly 100c extends beyond the second insulating layer 126 to the interconnector 122 of the connecting portion 120a on the upper surface side of the membrane electrode assembly 100c, and contacts the interconnector 122. Yes.

The cathode catalyst layer 104 of the membrane electrode assembly 100 b is located near the boundary between the electrolyte membrane 102 and the first insulating layer 124 at the end on the membrane electrode assembly 100 c side. Therefore, the cathode catalyst layer 104 of the membrane electrode assembly 100b and the interconnector 122 of the connection part 120a are not in contact with each other. Further, the anode catalyst layer 106 of the membrane electrode assembly 100 c is located near the boundary between the electrolyte membrane 102 and the gas seal portion 132 at the end on the membrane electrode assembly 100 b side. Therefore, the anode catalyst layer 106 of the membrane electrode assembly 100c and the interconnector 122 of the connecting portion 120a are not in contact with each other.

A water channel portion 128 is provided between the second insulating layer 126 and the membrane electrode assembly 100c. The water channel portion 128 has a function of connecting the cathode catalyst layer 104 and the anode catalyst layer vicinity region 102a of the electrolyte membrane 102 and allowing movement of water contained in the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a. The water contained in the cathode catalyst layer 104 is, for example, water generated in the cathode catalyst layer 104 by an electrochemical reaction, water moved from the electrolyte membrane 102 to the cathode catalyst layer 104, or the like. By providing the water channel portion 128, water can be transferred from the cathode catalyst layer 104 containing a large amount of water to the anode catalyst layer vicinity region 102 a of the electrolyte membrane 102 that is easy to dry, and the anode catalyst is passed through the electrolyte membrane 102. Water can also be transferred to the layer 106. Thereby, drying of the anode catalyst layer vicinity region 102a and the anode catalyst layer 106 of the electrolyte membrane 102 can be suppressed. The thickness of the water channel part 128, that is, the distance from the interface between the water channel part 128 and the second insulating layer 126 to the interface between the water channel part 128 and the waterproof part 130 is, for example, 100 to 500 μm. Here, the anode catalyst layer vicinity region 102 a is, for example, a plane that bisects the electrolyte membrane 102 in the thickness direction of the electrolyte membrane 102, that is, a plane that is equidistant from the cathode catalyst layer 104 and the anode catalyst layer 106 ( Hereinafter, this plane will be referred to as a central plane as appropriate) and at least a part of a region closer to the anode catalyst layer 106 side.

The water channel part 128 of this embodiment has a water absorbing material. As the water absorbing material, an inorganic water absorbing material such as silica gel, or an organic water absorbing material such as cellulose or rayon is used. In addition, you may use for the water channel part 128 what filled the base material, such as glass fiber, with said water absorbing material as a filler. Since the water channel portion 128 has the water absorbing material, water naturally moves from the larger water content to the smaller water content (from the higher humidity to the lower one) in the water channel portion 128. That is, in the water channel portion 128, water moves according to the water content gradient. In the fuel cell 10 of the present embodiment, water is generated in the cathode catalyst layer 104 by an electrochemical reaction. Therefore, the gradient of water content is usually high on the cathode catalyst layer 104 side and low on the anode catalyst layer vicinity region 102a side. As described above, since the water content can be naturally gradient at the same time as the electrochemical reaction starts, water can be transferred from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a with excellent responsiveness. . In addition, the water channel part 128 may be configured by a space surrounded by the second insulating layer 126 and a waterproof part 130 and a gas seal part 132 described later. In this case, water can be transferred from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a using a capillary phenomenon or the like or using air blown by a blower described later.

The water channel portion 128 is disposed on the side surface side of the membrane electrode assembly 100c. In the water channel portion 128, the end surface 128a (upper surface in FIG. 3) on the cathode catalyst layer 104 side is in contact with the cathode catalyst layer 104, and the side surface 128b on the anode catalyst layer side end is in contact with the anode catalyst layer vicinity region 102a. A substantially plate-shaped waterproof part 130 is interposed between the water channel part 128 and the membrane electrode assembly 100c. The waterproof portion 130 can more reliably ensure the flow of water from the cathode catalyst layer 104 side to the anode catalyst layer vicinity region 102a side in the water channel portion 128, so that the water in the water channel portion 128 can be more reliably supplied to the anode catalyst. The layer vicinity region 102a can be reached. In addition, it is preferable that the waterproof part 130 has gas impermeability and insulation. Thereby, generation | occurrence | production of the cross leak and short circuit through the waterproof part 130 can be suppressed. The waterproof part 130 may be made of the same material as the first insulating layer 124 and the second insulating layer 126.

The waterproof portion 130 of the present embodiment is in contact with the region of the side surface of the water channel portion 128 excluding the side surface 128b at the anode catalyst layer side end portion and the side surface 128c at the cathode catalyst layer side end portion. That is, the side surface 128b of the end portion on the anode catalyst layer side is in contact with the anode catalyst layer vicinity region 102a of the electrolyte membrane 102, and the side surface 128c of the cathode catalyst layer side end portion is the region near the cathode catalyst layer of the electrolyte membrane 102. 102b is touched. Since the water channel portion 128 is in contact with the cathode catalyst layer vicinity region 102b, water in the cathode catalyst layer vicinity region 102b having a relatively large water content can also be transferred to the anode catalyst layer vicinity region 102a. Therefore, drying of the anode catalyst layer vicinity region 102a and the anode catalyst layer 106 can be further suppressed. Moreover, the waterproof part 130 is disposed so as to be embedded in the electrolyte membrane 102. Therefore, the joint surface between the waterproof portion 130 and the water channel portion 128 and the joint surface between the water channel portion 128 and the electrolyte membrane 102 are located on the same plane. Here, the cathode catalyst layer vicinity region 102b refers to, for example, at least a part of the region closer to the cathode catalyst layer 104 than the center surface of the electrolyte membrane 102 described above.

By adjusting the contact area between at least one of the cathode catalyst layer 104, the anode catalyst layer vicinity region 102a, and the cathode catalyst layer vicinity region 102b and the water passage portion 128, adjusting the water absorption performance of the water passage portion 128, and the like, the anode catalyst layer vicinity region 102a. The amount of water transferred to the water can be controlled. Thereby, the occurrence of flooding in the anode catalyst layer 106 can be suppressed.

The end surface 128d (the lower surface in FIG. 3) on the anode catalyst layer side of the water channel portion 128 is covered with a substantially plate-like gas seal portion 132. The gas seal part 132 is a seal member that suppresses gas movement between the anode catalyst layer 106 side and the cathode catalyst layer 104 side via the water channel part 128, and the gas seal part 132 passes the water channel part 128 via the water channel part 128. The occurrence of cross leak can be suppressed. It is preferable that the gas seal part 132 has insulation and waterproofness. Generation | occurrence | production of a short circuit can be suppressed because the gas-seal part 132 has insulation. Moreover, since the gas seal part 132 has waterproofness, leakage of water from the water channel part 128 to the fuel gas chamber 18 described later can be suppressed. In the present embodiment, the gas seal portion 132 and the second insulating layer 126 are integral. Therefore, it can be said that the second insulating layer 126 has a function of suppressing the occurrence of cross leak through the water channel portion 128. Thereby, the increase in the number of parts of the fuel cell 10 can be suppressed.

The water channel portion 128 is made of a material different from that of the electrolyte membrane 102. Here, the water channel part 128 may have non-proton conductivity. Thereby, it is possible to suppress the conduction of protons from the anode catalyst layer 106 to the cathode catalyst layer 104 through the water channel portion 128, and the transfer of water from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a is prevented. It is possible to suppress obstruction. Further, the water channel portion 128 may be a proton conductive material having a proton conductivity lower than that of the electrolyte membrane 102. If the proton conductivity of the material constituting the water channel portion 128 is lower than that of the electrolyte membrane 102, the proportion of protons passing through the water channel portion 128 during power generation is smaller than that of the electrolyte membrane 102. Therefore, compared to the case where the water channel portion 128 is made of the same proton conductivity material as that of the electrolyte membrane 102, it is possible to suppress the hindering of water transfer from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a. it can.

Between the side surface of the membrane electrode assembly 100b located on the outermost side of the planar arrangement and the side surfaces of the cathode housing 12 and the anode housing 14, an outer connection portion 140 is interposed. The outer connection part 140 includes a second insulating layer 126, a water channel part 128, a waterproof part 130, and a gas seal part 132. A first insulating layer 124 is interposed between the side surface of the other outermost membrane electrode assembly 100 a and the side surfaces of the cathode housing 12 and the anode housing 14. In the plurality of membrane electrode assemblies 100, the second insulating layer 126 of the outer connecting portion 140 located on one outermost side and the first insulating layer 124 located on the other outermost side are composed of the cathode housing 12 and the anode. By being sandwiched between the housings 14, the housing 14 is fixed in a housing space formed by the cathode housing 12 and the anode housing 14. A gasket or the like may be disposed at the joint between the cathode housing 12 and the anode housing 14 or at the joint between the first insulating layer 124 and the second insulating layer 126 in order to ensure gas sealability. .

The cathode housing 12 is a member constituting a part of the exterior of the fuel cell 10 and is disposed so as to face the cathode catalyst layer 104. The cathode housing 12 is provided with a plurality of openings 12a for taking in air from the outside. An air chamber 16 through which air flows is provided between the cathode housing 12 and the cathode catalyst layer 104.

The anode housing 14 is a member constituting a part of the exterior of the fuel cell 10 and is disposed so as to face the anode catalyst layer 106. Between the anode housing 14 and the anode catalyst layer 106, a fuel gas chamber 18 for distributing fuel gas supplied from the outside to the anode catalyst layer 106 is provided. For example, the anode housing 14 is provided with a fuel supply port (not shown), and fuel gas is supplied from an external fuel cartridge.

In the present embodiment, each membrane electrode assembly 100 has a substantially rectangular shape when viewed from a direction perpendicular to the main surface of the membrane electrode assembly 100 (see FIG. 2B), and the connection portion of the membrane electrode assembly 100 A water channel portion 128 extends over the entire side surface in contact with 120 or the outer connecting portion 140. Thereby, compared with the case where the water channel part 128 is arrange | positioned in a part of the said side surface of the membrane electrode assembly 100, water can be transferred to the wider range of the anode catalyst layer vicinity area | region 102a. The water channel portion 128 may be disposed on a part of the side surface for the purpose of adjusting the amount of water transferred to the anode catalyst layer vicinity region 102a.

In this embodiment, the water channel part 128 is provided in the connection part 120. That is, the water channel part 128 is incorporated in the connection part 120. More specifically, the water channel portion 128 is disposed in a space formed by reducing the thickness of the second insulating layer 126. Therefore, an increase in the size of the fuel cell 10 due to the provision of the water channel portion 128 can be suppressed. The water channel portion 128 may also be provided between the first insulating layer 124 and the membrane electrode assembly 100b. That is, each membrane electrode assembly 100 may be sandwiched between two water channel portions 128. In this case, the water channel portion 128 is disposed in a space formed by reducing the thickness of the first insulating layer 124. Thereby, water can be transferred to a wider range of the anode catalyst layer vicinity region 102 a while suppressing an increase in the size of the fuel cell 10. Furthermore, when an increase in the size of the fuel cell 10 is allowed, the water channel portion 128 may be provided on the side surface of the membrane electrode assembly 100 extending perpendicularly to the extending direction of the connecting portion 120.

(Fuel cell manufacturing process)
Then, the manufacturing method of the fuel cell 10 which concerns on Embodiment 1 is demonstrated. 4 (A) to 4 (C), 5 (A) to 5 (C), 6 (A), and 6 (B) are steps showing a method of manufacturing the fuel cell according to the first embodiment. FIG. FIG. 4C is a schematic cross-sectional view taken along the line CC of FIG. 4B. 5A to 5C, FIG. 6A, and FIG. 6B, the three membrane electrode assemblies 100 including the outermost membrane electrode assembly 100b in the fuel cell 10 are illustrated. Is shown as an example.

First, as shown in FIG. 4A, a first insulating layer 124, an interconnector 122, a second insulating layer 126 in which a gas seal portion 132 is integrally provided, and a water channel in which a base material is impregnated with a water absorbing material. The part 128 and the waterproof part 130 are laminated in this order. In addition, the crimping spacers 200 are disposed on both sides of the waterproof part 130. Then, the laminate is heat-pressed using a press. After the thermocompression bonding, the pressure bonding spacer 200 is removed. As a result, as shown in FIGS. 4B and 4C, the connecting portion 120 is formed.

Next, as shown in FIG. 5A, the connecting portions 120 are arranged on the base 210 with a predetermined interval. In this embodiment, the connection part 120 is arrange | positioned so that the gas seal part 132 may contact | connect the base 210. FIG. An outer connection portion 140 is disposed on one outermost side of the array of the connection portions 120. The outer connecting portion 140 is a laminated body of the second insulating layer 126 integrally provided with the gas seal portion 132, the water channel portion 128 in which the base material is impregnated with the water absorbing material, and the waterproof portion 130. It is manufactured in the same process as 120. A first insulating layer 124 is disposed on the other outermost side of the arrangement of the connection portions 120 (see FIG. 2A).

Next, as shown in FIG. 5B, an electrolyte solution containing an ion exchanger such as Nafion is applied to the space between the connection portions 120, and the electrolyte solution is dried to form the electrolyte membrane 102.

Next, as shown in FIG. 5C, the cathode slurry 103 is applied to one main surface of the plate-like body constituted by the electrolyte membrane 102, the connection portion 120, and the outer connection portion 140, and dried. The cathode slurry 103 is applied to the main surface on the side where the water channel portion 128 is exposed. Also, the anode slurry 105 is applied to the other main surface of the plate-like body and dried. The anode slurry 105 is applied to the main surface on the side where the gas seal portion 132 is exposed.

Next, as shown in FIG. 6A, predetermined regions of the cathode slurry 103 and the anode slurry 105 are removed by laser irradiation or the like to form the cathode catalyst layer 104 and the anode catalyst layer 106. The cathode catalyst layer 104 and the anode catalyst layer 106 are provided with a masking material in a predetermined region before the cathode slurry 103 and the anode slurry 105 are applied, and after the cathode slurry 103 and the anode slurry 105 are applied, the masking material is removed. You may form by.

Next, as shown in FIG. 6B, the cathode housing 12 is provided on the cathode catalyst layer 104 side, and the anode housing 14 is provided on the anode catalyst layer 106 side. The fuel cell 10 is manufactured through the above steps.

As described above, the fuel cell 10 according to Embodiment 1 includes the membrane electrode assembly 100 including the electrolyte membrane 102, the cathode catalyst layer 104, and the anode catalyst layer 106, and the anode of the cathode catalyst layer 104 and the electrolyte membrane 102. A water channel portion 128 that connects the catalyst layer vicinity region 102a and allows movement of water contained in the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a is provided. Thereby, it is possible to suppress drying of the anode catalyst layer 106 and the anode catalyst layer vicinity region 102a of the electrolyte membrane 102, which are easier to dry than the cathode catalyst layer 104 and the cathode catalyst layer vicinity region 102b of the electrolyte membrane 102. Therefore, the power generation performance of the fuel cell 10 can be improved.

(Embodiment 2)
The fuel cell 10 according to the second embodiment is common to the configuration and the manufacturing method of the fuel cell 10 according to the first embodiment, except for the structure of the connecting portion 120 and the manufacturing method. Hereinafter, the fuel cell 10 according to the second embodiment will be described focusing on the configuration different from the first embodiment. In addition, the same code | symbol is attached | subjected about the structure same as Embodiment 1, and the description is abbreviate | omitted suitably. FIG. 7 is a cross-sectional view partially showing the schematic structure of the fuel cell according to the second embodiment. Note that FIG. 7 corresponds to a region B surrounded by a broken line in FIG.

In the fuel cell 10 according to Embodiment 2, the waterproof part 130 is arranged so as to be embedded in the water channel part 128. Therefore, the joint surface between the waterproof portion 130 and the electrolyte membrane 102 and the joint surface (that is, the side surfaces 128b and 128c) between the water channel portion 128 and the electrolyte membrane 102 are located on the same plane. An extension 134 made of the same material as the gas seal 132 is connected to the gas seal 132. The extension part 134 is interposed between the end face 128d of the water channel part 128 on the anode catalyst layer 106 side and the anode catalyst layer 106, and the gas seal part 132 and the extension part 134 cause a cross leak and a short circuit via the water channel part 128. Occurrence is suppressed. The gas seal portion 132 and the extension portion 134 may be integrated.

8 (A) to 8 (D) are process diagrams showing a method of manufacturing a fuel cell according to the second embodiment. Here, only the manufacturing process of the connecting portion 120, which is different from the manufacturing method of the fuel cell according to the first embodiment, will be described.

First, as shown in FIG. 8A, a first insulating layer 124, an interconnector 122, and a second insulating layer 126 integrally provided with a gas seal portion 132 are laminated in this order. Further, the extension part 134 is stacked on the gas seal part 132, and the waterproof part 130 is stacked on the second insulating layer 126 with a predetermined distance from the extension part 134. Then, the laminate is heat-pressed using a press. Thereby, a complex 119 is formed as shown in FIG.

Next, as shown in FIGS. 8C and 8D, the space 127 surrounded by the second insulating layer 126, the waterproof portion 130, and the gas seal portion 132 in the composite body 119 is filled with a water absorbing material. Thus, the water channel portion 128 is formed. The water absorbing material is filled up to the same height as the upper surfaces of the waterproof part 130 and the extension part 134. Thereby, the connection part 120 is formed. Thereafter, the steps shown in FIGS. 5A to 5C, FIG. 6A, and FIG. 6B are performed, and the fuel cell 10 is obtained.

According to the fuel cell 10 according to the second embodiment described above, the area of the end surface 128a of the water channel portion 128 on the cathode catalyst layer 104 side can be increased, so that the contact area between the water channel portion 128 and the cathode catalyst layer 104 is reduced. A design larger than that of the first embodiment is possible. Therefore, the amount of water transferred from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a can be further increased.

(Embodiment 3)
Embodiment 3 is a fuel cell system equipped with the fuel cell 10 according to Embodiment 1 or 2 described above. The same components as those in the first or second embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

FIG. 9A is a perspective view of the fuel cell system according to Embodiment 3 as viewed obliquely from above. FIG. 9B is a perspective view of the fuel cell system according to Embodiment 3 as viewed obliquely from below. FIG. 10A is a front view showing a schematic structure inside the housing of the fuel cell system according to Embodiment 3. FIG. FIG. 10B is a perspective view showing a schematic structure inside the housing of the fuel cell system according to the third embodiment. In FIG. 10A, the membrane electrode assembly 100 and the water channel 128 of the fuel cell 10 are schematically shown.

The fuel cell system 1 includes a housing 300, a plurality of fuel cells 10, a fuel storage unit 330, a fuel supply unit 332, a blower unit 340, a rectifying unit 350, and a control unit 370. The fuel cell system 1 of the present embodiment is a passive fuel cell system that does not use an auxiliary machine such as a pump for supplying fuel. The housing 300 contains a plurality of fuel cells 10, a fuel storage unit 330, a fuel supply unit 332, a blower unit 340, a rectifying unit 350, and a control unit 370 in a compact form that is easy to carry. As shown in FIG. 9A, most of the housing 300 is integrally formed, but for convenience, it is mainly divided into a base portion 310 and a protruding portion 320.

The base portion 310 has a rectangular parallelepiped shape, and leg portions 312 for mounting on a setting surface such as a desk are provided at both longitudinal ends of the bottom surface. An air inlet 314 is provided on the bottom surface of the base 310, and outside air is taken into the base 310 through the air inlet 314. In the bottom surface of the base 310, a region where the air inlet 314 is provided is a concave portion with respect to the leg 312, and the leg 312 is in contact with the installation surface and between the installation surface and the air intake 314. A gap is created. Thereby, outside air can be taken in from the bottom surface of the base 310 in a state where the housing 300 is placed on the installation surface. The number and position of the air inlets 314 are appropriately set according to the form of the air blowing unit 340 described later.

Further, the upper surface of the base 310 is divided into a region M along one side along the longitudinal direction and a region N along the other side along the longitudinal direction (see FIG. 9A). In the region M, two sets of

exhaust ports

316a and 316b are provided. In the region N, two sets of exhaust ports (not shown) are provided as in the region M.

The protruding portion 320 protrudes above the base portion 310 in a region sandwiched between the region M and the region N. The casing 300 has an inverted T shape when viewed from the side.

Openings

318m, 318n, 318o and 318p corresponding to the installation area of the fuel cell 10 provided on the region M side are provided on one side of the protrusion 320 (region M side). Similarly, openings 318m ′, 318n ′, 318o ′ and 318p ′ corresponding to the installation area of the fuel cell 10 provided on the region N side are provided on the other side (region N side) of the protrusion 320. It has been.

Hereinafter, the case 300 will be described in more detail by taking the region M side of the protrusion 320 as an example. The

openings

318m, 318n, 318o, and 318p are arranged in a 2 × 2 matrix, and the openings 318m and 318o are arranged in the vicinity of the exhaust port 316a and the exhaust port 316b, respectively. The opening 318n is located above the opening 318m. The opening 318p is located above the opening 318o. A reinforcing portion 301a is provided between the opening 318m and the opening 318n and between the opening 318o and the opening 318p. In other words, the reinforcing portion 301a extends in a direction orthogonal to the blowing direction from the

exhaust ports

316a and 316b (the direction of the arrow X in FIG. 9A). By providing the reinforcing portion 301 a, the fuel cell 10 can be held more stably in the housing 300. Details of the reinforcing portion 301a will be described later.

Reinforcing portions 301b are provided between the opening 318m and the opening 318o and between the opening 318n and the opening 318p. In other words, the reinforcement part 301b is extended along the ventilation direction from the

exhaust port

316a, 316b. By providing the reinforcing portion 301b, the fuel cell 10 can be more stably held in the housing 300 in the same manner as the reinforcing portion 301a.

A plurality of fuel cells 10, a fuel storage unit 330, and a fuel supply unit 332 are stored in the protrusion 320.

The fuel storage unit 330 stores a hydrogen storage alloy. The hydrogen storage alloy can store hydrogen and release the stored hydrogen, and is, for example, rare earth-based MmNi _4.32 Mn _0.18 Al _0.1 Fe _0.1 Co _0.3 (Mm is Misch metal). The hydrogen storage alloy is not limited to this, but other rare earth alloys such as La—Ni alloys, Ti—Mn alloys, Ti—Fe alloys, Ti—Zr alloys, Mg—Ni alloys. Zr—Mn alloy or the like may be used. Specifically, LaNi ₅ alloy, _Mg 2 Ni _{_{_{alloy, Ti 1 + x Cr 2-}}} y Mn y (x = 0.1 ~ 0.3, y = 0 ~ 1.0) as a hydrogen storage alloy and the like alloys Can do. The hydrogen storage alloy can be formed into a compression molded body (pellet) obtained by mixing a binder such as polytetrafluoroethylene (PTFE) dispersion into the above-mentioned hydrogen storage alloy powder and compression molding with a press. If necessary, a sintering process may be performed after the compression molding. The hydrogen storage alloy may not be in the form of a pellet, but may be one in which the fuel storage space is filled with a powder of the hydrogen storage alloy. The shape of the hydrogen storage alloy is not particularly limited.

Fuel cells 10 are disposed on both main surfaces of the fuel storage unit 330, respectively. In the present embodiment, the four fuel cells 10 are arranged in a plane on both main surfaces of the fuel storage portion 330 so as to overlap the four openings 318 provided in the protruding portion 320 of the housing 300. The fuel cell 10 is a fuel cell according to the first embodiment or the second embodiment described above. In the present embodiment, the cathode protective layer 400 described later constitutes the cathode housing of the four fuel cells 10.

The fuel cell 10 is arranged so that the main surface on the cathode catalyst layer 104 side faces the outside of the fuel cell system 1. The cathode protective layer 400 disposed on the cathode catalyst layer 104 side is formed of a flat plate-like member, and has a plurality of openings 401 like the cathode housing 12 (see FIG. 11A). These openings 401 provide air permeability between the cathode catalyst layer 104 and the outside of the fuel cell. The material of the cathode protective layer 400 is not particularly limited, and examples thereof include insulators such as anodized aluminum and polyacrylate. A gas-liquid separation membrane (not shown) may be provided between the cathode protective layer 400 and the cathode catalyst layer 104.

In the present embodiment, the main surface of the fuel cell 10 on the cathode catalyst layer 104 side faces outward. Therefore, the main surface of the fuel cell 10 blown by the blower 340 is the main surface on the cathode catalyst layer 104 side. Therefore, the supply of air as an oxidant gas and the supply of air for cooling the fuel cell 10 can be achieved by the blower 340. A temperature detection unit (not shown) is provided on the main surface of the fuel cell 10 on the cathode catalyst layer 104 side. The temperature of the fuel cell 10 is measured by the temperature detector, and the temperature information of the fuel cell 10 obtained by the temperature detector is transmitted to the controller 370 described later.

The fuel supply unit 332 includes a hydrogen supply path and a regulator (both not shown) as main components. One end of the hydrogen supply path communicates with the outlet of the fuel storage unit 330, and the other end communicates with the anode catalyst layer 106 side of the fuel cell 10. A regulator is provided in the middle of the hydrogen supply path. When the hydrogen is released from the hydrogen storage alloy by the regulator, the pressure of the hydrogen supplied to the fuel cell 10 is reduced. Thereby, the anode catalyst layer 106 of the fuel cell 10 is protected.

The base 310 mainly accommodates a blower 340, a rectifier 350, and a controller 370.

The control unit 370 is mounted on a member that forms the bottom surface of the base 310. The control unit 370 includes a CPU, a ROM, a memory, and the like as a hardware configuration, and controls the operation of the air blowing unit 340. For example, the control unit 370 starts the blowing by the blowing unit 340 when the temperature measured by the temperature detection unit reaches a predetermined high temperature.

The blower 340 is installed above the controller 370. The blower 340 blows air from a direction orthogonal to the main surface of the fuel cell 10 on the cathode catalyst layer 104 side. In this embodiment, two sets of blowers 342 that generate a swirling flow are arranged in parallel in the longitudinal direction of the base 310 as the blower 340. Specifically, the blower 342 is an axial fan (propeller fan). The wind generated by one of the blowers 342 is blown to both the exhaust port 316a on the region M side and the exhaust port 316a on the region N side with the projecting portion 320 as an axis of symmetry and the exhaust port located in line symmetry. In addition, the wind generated by the other blower 342 is blown to both the exhaust port 316b on the region M side and the exhaust port 316b on the region N side with the projecting portion 320 as an axis of symmetry and the exhaust port located in line symmetry. In this way, the configuration is simplified by taking charge of the air to the fuel cells 10 respectively provided on the two main surfaces of the fuel storage portion 330 with one blower, and the fuel cell system 1 is made compact and saves power. be able to.

The rectifying unit 350 is provided above the air blowing unit 340. The rectifying unit 350 makes an angle so that the direction of the wind sent from the air blowing unit 340 faces the main surface of the fuel cell 10 on the cathode catalyst layer 104 side. Specifically, it has a rectifying plate 352 having a shape that reflects the swirling flow generated by the blower 340 toward the main surface of the fuel cell 10 on the cathode catalyst layer 104 side.

The blower 340 blows along the main surface of the fuel cell 10 on the cathode catalyst layer 104 side. In FIG. 10A, the arrow X represents the wind. The fuel cell 10 is arranged such that the extending direction of the water channel portion 128 is substantially perpendicular to the blowing direction of the blowing unit 340. That is, the series connection direction of the membrane electrode assembly 100 and the blowing direction of the blowing unit 340 are parallel. Further, each combination Z of the membrane electrode assembly 100 and the water channel portion 128 (for example, the combination of the membrane electrode assembly 100b and the water channel portion 128 of the outer connection portion 140 shown in FIG. 3, and the membrane electrode assembly 100c) In combination with the water channel portion 128 of the portion 120a), the membrane electrode assembly 100 is disposed on the leeward side of the air blowing unit 340, and the water channel portion 128 is disposed on the leeward side of the air blowing unit 340 in the air blowing direction. Thereby, the water contained in the cathode catalyst layer 104 can be moved to the water channel part 128 by the air blowing of the air blowing part 340. In order to prevent a short circuit from occurring when the air of the membrane electrode assembly 100 on the windward side passes through the adjacent connecting portion 120 and reaches the membrane electrode assembly 100 on the leeward side by blowing air, the interconnector 122 is connected to the cathode. The connecting layer 120 may be protruded upward from the catalyst layer 104, or a bank portion protruding above the cathode catalyst layer 104 may be provided on the end surface of the connecting portion 120.

FIG. 11A is an enlarged schematic plan view of the reinforcing portion 301a and the reinforcing portion 301b. FIG. 11B is a schematic cross-sectional view along the line EE in FIG. FIG. 11C is a cross-sectional view taken along the line FF in FIG. In FIGS. 11A and 11C, the arrow X represents the wind.

The thickness of the reinforcing part 301a is thinner than the thickness of the reinforcing part 301b, the reinforcing part 301b is convex on the fuel cell 10 side, and the reinforcing part 301a and the reinforcing part 301b are on the opposite side (outside) from the fuel cell 10. It is designed so that there is no step between them. Thereby, a flow path 410 serving as a path for the wind X is formed between the reinforcing portion 301 a and the cathode protective layer 400. According to this, the

openings

318n and 318p including the region behind the reinforcing portion 301a as viewed from the blowing portion 340 without being blocked by the reinforcing portion 301a when the wind sent from the blowing portion 340 passes through the flow path 410. Can head to. Therefore, since it is possible to blow air over the entire main surface of the fuel cell 10 on the cathode catalyst layer 104 side with a uniform air volume, it is possible to reduce variations in temperature depending on the location, and to stabilize power generation by the fuel cell 10. be able to.

In the region where the reinforcing

portions

301a and 301b have the same thickness and the reinforcing portion 301a and the reinforcing portion 301b intersect, the reinforcing portion 301a is above the reinforcing portion 301b (the reinforcing portion 301b is more fuel cell than the reinforcing portion 301a). (10 side) may be arranged. In this case, a flow path 410 equivalent to the thickness of the reinforcing portion 301b can be formed between the reinforcing portion 301a and the cathode protective layer 400.

According to the fuel cell system 1 described above, the water contained in the cathode catalyst layer 104 can be moved to the water channel portion 128 using the air blow for supplying air to the cathode catalyst layer 104 of the fuel cell 10. . Thereby, water can be efficiently transferred from the cathode catalyst layer 104 to the anode catalyst layer vicinity region 102a.

The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art, and the embodiments to which such modifications are added. Can also be included in the scope of the present invention.

In the first to third embodiments described above, the side surface 128b of the end portion of the water channel portion 128 on the anode catalyst layer side is in contact with the anode catalyst layer vicinity region 102a, and the water channel portion 128 and the anode catalyst layer 106 are not in contact with each other. If 128 is capable of flowing water and has gas impermeability, the side surface 128b may be in contact with the anode catalyst layer 106 in addition to the anode catalyst layer vicinity region 102a, or only on the anode catalyst layer 106. You may touch.

DESCRIPTION OF SYMBOLS 1 Fuel cell system, 10 Fuel cell, 100 Membrane electrode assembly, 102 Electrolyte membrane, 102a Anode catalyst layer vicinity area, 102b Cathode catalyst layer vicinity area, 104 Cathode catalyst layer, 106 Anode catalyst layer, 122 Interconnector, 124 1st Insulating layer, 126, second insulating layer, 128 waterway part, 130 waterproofing part, 132 gas seal part, 340 air blowing part.

The present invention can be used for fuel cells and fuel cell systems.

Claims

A membrane electrode assembly comprising an electrolyte membrane, a cathode catalyst layer provided on one surface of the electrolyte membrane, and an anode catalyst layer provided on the other surface of the electrolyte membrane;
It is made of a material different from that of the electrolyte membrane, connects the cathode catalyst layer and the region near the anode catalyst layer of the electrolyte membrane, and allows water contained in the cathode catalyst layer to move to the region near the anode catalyst layer. A waterway to
A fuel cell comprising:
The fuel cell according to claim 1, wherein the water channel portion has a water absorbing material.
The water channel part is disposed on a side surface side of the membrane electrode assembly, and a side surface of the water channel unit is in contact with a region near the anode catalyst layer,
The fuel cell according to claim 1, further comprising a waterproof part interposed between the water channel part and the membrane electrode assembly.
The gas seal part which coat | covers the end surface by the side of the anode catalyst layer of the said water channel part, and suppresses the movement of the gas between the said anode catalyst layer side and the said cathode catalyst layer side via the said water channel part is provided. 4. The fuel cell according to any one of items 1 to 3.
The fuel cell according to any one of claims 1 to 4, wherein the water channel portion is in contact with a region near the cathode catalyst layer of the electrolyte membrane.
A plurality of membrane electrode assemblies arranged in a plane;
An interconnector for electrically connecting one anode catalyst layer and the other cathode catalyst layer of an adjacent membrane electrode assembly;
An insulating layer interposed between the membrane electrode assembly and the interconnector,
The fuel cell according to any one of claims 1 to 5, wherein the water channel portion is provided between the insulating layer and the membrane electrode assembly.
A gas seal portion that covers an end surface of the water channel portion on the anode catalyst layer side and suppresses gas movement between the anode catalyst layer and the cathode catalyst layer via the water channel portion;
The fuel cell according to claim 6, wherein the gas seal portion and the insulating layer are integrated.
The fuel cell according to any one of claims 1 to 7, wherein the water channel portion has aprotic conductivity.
The fuel cell according to any one of claims 1 to 7, wherein the water channel portion is made of a proton conductive material having a proton conductivity lower than that of the electrolyte membrane.
The fuel cell according to any one of claims 1 to 9,
An air blowing section for blowing air along the cathode catalyst layer side main surface of the fuel cell,
The said water channel part is arrange | positioned in the leeward side of the ventilation direction of the said ventilation part, The fuel cell system characterized by the above-mentioned.