JP6368996B2 - Membrane electrode assembly - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a membrane electrode assembly constituting a polymer fuel cell, which ensures transportation and is free from defects due to rubbing or damage when removing a protective sheet.

  In recent years, fuel cells have attracted attention as a countermeasure against environmental problems and energy problems. A fuel cell is one that obtains electricity by converting chemical energy associated therewith into electric energy in a reaction of oxidizing a reducing gas such as hydrogen or methane with an oxidizing gas such as oxygen or air. It is considered to be clean energy because there are abundant substances that can be used as raw materials and because the power generated is only water.

  Fuel cells are classified into alkaline type, phosphoric acid type, polymer type, molten carbonate type, solid oxide type, etc., depending on the type of electrolyte, of which polymer type fuel cell (PEFC) operates at low temperature, Since it has a high power density and can be reduced in size and weight, it is expected to be used as a portable power source, a household power source, and an in-vehicle power source.

  A polymer fuel cell has a structure in which a fuel electrode (anode) catalyst layer is provided on one surface of an electrolyte membrane and an air electrode (cathode) catalyst layer is provided on the other surface so as to face each other. A layer structure or a five-layer structure in which a gas diffusive and conductive diffusion layer is attached to both sides thereof is called a membrane electrode assembly (MEA).

  In a membrane electrode assembly, in order to prevent gas leakage due to a difference in thickness between a region where the catalyst layer is formed in the electrolyte membrane and a region where the catalyst layer is not formed, and intensive deterioration of the region where the catalyst layer is not formed in the electrolyte In general, the gasket member is provided outside the catalyst layer on the electrolyte membrane.

  The membrane electrode assembly is sandwiched between plate-like members called separators, which are stacked to form a fuel cell stack.

  The membrane electrode assembly may be supplied as a member of a polymer electrolyte fuel cell in the above-described three-layer or five-layer state. Conventionally, transportation of a plurality of membrane electrode assemblies has been carried out in a state in which the membrane electrode assemblies themselves are stacked or in a state in which the membrane electrode assemblies are packaged one by one.

  In that case, the gas diffusion layer and catalyst layer of a membrane electrode assembly may be impaired by the contact between membrane electrode assemblies or the contact between a membrane electrode assembly and a packaging material. In order to avoid this problem, a membrane electrode assembly with a protective sheet is disclosed in Document 1. However, in Reference 1, the protective sheet is directly bonded so as to cover the membrane electrode assembly, so that the gas diffusion layer and the catalyst layer are prevented from being damaged due to rubbing with the protective sheet and damage when the protective sheet is removed. Can not.

Japanese Patent No. 5152290

The present invention provides a membrane electrode assembly that constitutes a polymer fuel cell, is simple while avoiding defects and damage of the gas diffusion layer, fuel electrode catalyst layer, and air electrode catalyst layer, which are problematic. The purpose is to enable transportation without loss of quality.

  As means for solving the above problems, one embodiment of the present invention includes an electrolyte membrane, a fuel electrode catalyst layer formed on one surface of the electrolyte membrane, and the fuel electrode on the other surface of the electrolyte membrane. A membrane electrode assembly including an air electrode catalyst layer formed to face the catalyst layer, wherein the electrolyte membrane has a long shape having a certain width, and the fuel electrode catalyst layer and the air electrode catalyst A layer is provided at a distance from the longitudinal direction of the electrolyte membrane, and a spacer is provided on the surface of the electrolyte membrane where the fuel electrode catalyst layer and the air electrode catalyst layer are not provided. And

  Further, a gasket member is provided between the electrolyte membrane and the spacer on the surface of the electrolyte membrane where the fuel electrode catalyst layer and the air electrode catalyst layer are not provided.

  Further, a diffusion layer is provided on the surfaces of the fuel electrode catalyst layer and the air electrode catalyst layer.

  The surface of the gasket member and the surface of the diffusion layer are flush with each other.

  The spacer can be peeled off from the electrolyte membrane or the gasket member.

  The spacer may be partially provided.

  The spacer has a thickness of 200 μm or more.

  Further, the spacer is provided in a band shape with a gap from the fuel electrode catalyst layer or the air electrode catalyst layer, and the gap is 0.5 mm or more and 10 mm or less with respect to the short direction of the electrolyte membrane. Features.

  In addition, an adhesive layer is provided on the outer surface of the spacer.

  By providing the spacer, it is possible to avoid contact of the other membrane electrode assembly with the fuel electrode catalyst layer, the air electrode catalyst layer, the diffusion layer, and the packaging material in the wound state and the expanded state. Since it is not necessary to modify the fuel electrode catalyst layer, the air electrode catalyst layer, the diffusion layer, or the like, which greatly affects the battery performance, the performance is not affected, and high accuracy is not required in forming the spacer. Furthermore, the cost is reduced because the amount of material required is small. In the present invention, it is possible to obtain a membrane electrode assembly capable of being transported easily and efficiently without impairing quality.

It is the conceptual diagram of the plane which showed an example of the membrane electrode assembly of this invention, and A-A 'and B-B' cross section. 1 is an exploded perspective view showing a configuration of a general polymer fuel cell. It is a figure explaining Example 1 and Comparative Examples 2 and 3. FIG. FIG. 6 is a diagram illustrating Example 2. FIG. 6 is a diagram for explaining a third embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of the configuration of a membrane electrode assembly 10 according to the present invention, in which a gasket member 3 having an opening is bonded to both sides of a long electrolyte membrane 2. A fuel electrode catalyst layer 6 is provided in the opening, an air electrode catalyst layer 7 is provided on the other surface, and a diffusion layer 4 is provided on the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7.

  On the gasket member 3, a spacer 1 is provided in a strip shape with a gap from the fuel electrode catalyst layer or the air electrode catalyst layer. At this time, the number of the spacers 1 is not particularly limited. Since the membrane electrode assembly 10 includes the spacer 1, the fuel electrode catalyst layer, the air electrode catalyst layer, and the diffusion layer of the other membrane electrode assembly can be obtained even when the membrane electrode assembly 10 is in a rolled state and in an expanded state. And contact with packaging materials can be avoided.

  FIG. 2 is an exploded perspective view showing a general configuration of one single cell of the polymer fuel cell. The single cell includes an electrolyte membrane 2 having a fuel electrode catalyst layer and an air electrode catalyst layer on both sides, a gasket member 3 disposed around the catalyst layer, a diffusion layer 4 disposed on the catalyst layer, and a gas flow path 8. It is comprised with the separator 5 which has. The present invention includes an electrolyte membrane 2 having a fuel electrode catalyst layer and an air electrode catalyst layer on both sides of the single cell in FIG. 2, a gasket member 3 disposed around the catalyst layer, and a diffusion layer 4 disposed on the catalyst layer. The present invention relates to a membrane electrode assembly including

<Electrolyte membrane 2>
The electrolyte membrane 2 is not particularly limited as long as it has a high ion conductivity, but in many cases, a perfluorosulfonic acid-based or hydrocarbon-based solid electrolyte membrane is used. Specific examples include Nafion: DuPont, Goreselect: Japan Gore-Tex, Flemion: Asahi Glass. The thickness of the electrolyte membrane 2 is not particularly limited, but is preferably 10 μm to 200 μm. If the thickness is smaller than this, the membrane is easily damaged and difficult to handle.

<Fuel electrode catalyst layer 6 and air electrode catalyst layer 7>
The fuel electrode catalyst layer 6 and the air electrode catalyst layer 6 are composed of a catalyst and an electrolyte. Catalyst particles include platinum, palladium, ruthenium, iridium, rhodium, osmium, platinum group elements, metals such as iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum Alloys, oxides and double oxides can be used.

  The catalyst particles may be used alone or more preferably supported on a conductive carrier. Carbon particles are generally used for the conductive carrier. It is not particularly limited as long as it is in the form of fine particles and has electrical conductivity and chemical resistance, and examples thereof include carbon black, graphite, graphite, activated carbon, carbon fiber, carbon nanotube, and fullerene. The particle size of the carbon particles is preferably about 10 to 1000 nm. If the particle size is smaller than this, it becomes difficult to form an electron conduction path, and if the particle size is larger, the thickness of the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 serving as electrode contacts increases. Will increase.

  The electrolyte used for the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 only needs to have ion conductivity. Use of the same material as that of the electrolyte membrane 2 is more preferable because adhesion between the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 and the electrolyte membrane 2 is improved.

  The means for forming the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 is not particularly limited. For example, even if a slurry in which the mixture of the catalyst particles, the carrier and the electrolyte described above is dispersed is directly wet-coated on the electrolyte membrane 2, the transfer substrate Alternatively, it may be applied to the diffusion layer 4 and formed by post-transfer. The formation of the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 is provided with a drying step as necessary. The drying method is not particularly limited, and examples include warm air drying, infrared drying, and reduced pressure drying.

<Gasket member 3>
The gasket member 3 plays the following role. It is known that when the electrolyte membrane 2 is exposed to the raw material or the generated gas, the deterioration is promoted, and by covering the portion of the electrolyte membrane 2 where the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 are not formed. One is to protect the electrolyte membrane 2 from gas. One is to eliminate the unevenness of the membrane electrode assembly 10 due to the fuel electrode catalyst layer 6, the air electrode catalyst layer 7, and the diffusion layer 4 described later, thereby making the assembly of the fuel cell easier and more accurate. is there.

  The gasket member 3 is required to have a strength that can withstand temperature changes and pressure loads, and a gas barrier property that does not allow the fuel gas and oxidant gas to leak, and is preferably made of a film. The gasket member 3 made of a film includes an adhesive layer or an adhesive layer on at least one surface of the film, and may include a release layer on the other surface. The pressure-sensitive adhesive layer or the adhesive layer is provided between the film and the electrolyte membrane 2 and improves the gas sealability at the interface. Also, other methods can be used, for example, a method of producing by applying an ink in which a material is dissolved.

  The material of the gasket member 3 is preferably a material that does not easily deform even when pressure is applied, and examples thereof include polymer materials such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamide. These may be used alone or in combination.

  The thickness of the gasket member 3 is preferably equal to the combined thickness of the fuel electrode catalyst layer 6 or the air electrode catalyst layer 7 and the diffusion layer 4 described later. That is, as shown in FIG. 1, the surface of the gasket member 3 and the surface of the diffusion layer 4 are preferably flush with each other. Thereby, the level | step difference of the surface of the gasket member 3 and the surface of the diffusion layer 4 can be eliminated, and adhesiveness with a separator can be improved.

  The surface of the electrolyte membrane 2 on which the fuel electrode catalyst layer 6 or the air electrode catalyst layer 7 is not provided, that is, the region on the electrolyte membrane 2 where the fuel electrode catalyst layer 6 or the air electrode catalyst layer 7 is not formed, or the gasket member 3 A spacer 1 to be described later is adhered and disposed on the surface. When the spacer 1 is attached to the surface of the gasket member 3, the spacer 1 is provided on the surface of the gasket member 3 that faces the adhesive surface with the electrolyte membrane 10. Hereinafter, the electrolyte membrane 2 or the gasket member 3 to which the spacer 1 is bonded is referred to as an adherend.

<Spacer 1>
The spacer 1 may be provided only on either the fuel electrode side or the air electrode side, or may be provided on both. It is particularly preferable to form the outer surface when wound.

  The spacer 1 can be peeled off from the material to be bonded, and the strength of peel adhesion between the spacer 1 and the material to be bonded (JIS K6854) is preferably 2.0 N / cm or less. When it is 1.0 N / cm or less, peeling is easier and it is preferable. The strength of peel adhesion between the spacer 1 and the adherend is adjusted by the material constituting the adhesive layer on the surface of the spacer 1 that adheres to the adherend. Here, an acrylic pressure-sensitive adhesive is suitable as a material constituting the pressure-sensitive adhesive layer. It is composed of a known adhesive (meth) acrylic acid ester as a main component and a cross-linking agent, a plasticizer, a surfactant and the like blended with a copolymer pressure-sensitive adhesive. Moreover, auxiliary agents, such as tackifier resin, a softening agent, various pigments, and a viscosity modifier, may be added as needed. The adhesive strength is adjusted by these materials and the blending ratio.

  Further, a part of the surface of the spacer 1 that is in contact with the adherend may be a part of the region to be bonded.

  In order to improve the adhesion when laminated, the spacer 1 has a structure having an adhesive layer on the surface opposite to the surface in contact with the adherend, that is, on the outer surface of the spacer 1, in addition to the surface adhering to the adherend. Good. The laminated assembly is further stabilized by being combined with another membrane electrode assembly 10 via the adhesive layer. The peel adhesion strength (JIS K6854) is preferably 2.0 N / cm or less, and more preferably 1.0 N / cm or less because peeling is easy.

  The height of the spacer 1 in the film thickness direction of the membrane electrode assembly 10 is 0.2 mm or more. When the thickness is 0.5 mm or more, there is a high possibility that contact with other membrane electrode assemblies and packaging materials in the electrode portion can be avoided even when bending or shaking occurs due to external force.

  The spacer 1 is provided on the material to be bonded, and is provided to avoid the belt-like region α (see FIG. 3) in which the fuel electrode catalyst layer 6 or the air electrode catalyst layer 7 is formed at intervals. The size and number are not limited. It is particularly preferable to form a continuous or discontinuous strip in parallel with the strip region α. At that time, the spacer 1 should not be in contact with the electrode part, but by being provided in the very vicinity, the vicinity of the electrode part can be more reliably supported and the space of the electrode part can be maintained. The distance in the short direction between the spacer 1 and the electrode part is preferably 0.5 mm or more and 10 mm or less, and more preferably 1 mm or more and 5 mm or less. When it is smaller than 0.5 mm, there is a possibility of contact with the catalyst layer or the like when the spacer 1 is stuck or peeled off, which is not preferable from the viewpoint of workability. On the other hand, when it is larger than 10 mm, the effect of maintaining the space of the electrode portion is reduced, which is not preferable.

  The spacer 1 is provided with a gap from the fuel electrode catalyst layer or the fuel electrode catalyst layer, and is preferably 0.5 mm or more and 10 mm or less with respect to the short direction of the electrolyte membrane. It is not limited to the upper and lower rows, and a plurality may be provided in parallel.

  The shape, size, and number of the spacers 1 are not particularly limited, and it is possible to protect the electrolyte membrane 2 or the gasket member 3 that is an adherend, but if the area where the spacers 1 are formed is reduced, Material costs can be reduced.

<Diffusion layer 4>
The diffusion layer 4 is made of a material having high conductivity and high material gas diffusibility. For example, a metal film, a conductive polymer, a carbon material and the like can be mentioned, and among them, a porous conductor material such as carbon paper is preferable. The thickness of the diffusion layer 4 is preferably about 50 μm to 1000 μm.

  There is a membrane electrode assembly 10 sandwiched between the diffusion layers 4. A fuel electrode catalyst layer 6 and an air electrode catalyst layer 7 to be a fuel electrode and an air electrode are formed on both surfaces of the electrolyte membrane 2, and a gap is not formed between the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 so as to surround the outside thereof. The gasket member 3 is disposed on the surface.

<Separator 5>
The separator 5 is made of a material that has conductivity and does not transmit gas. For example, a metal plate subjected to corrosion resistance treatment or a carbon-based material such as baked carbon. The separator 5 faces the air electrode and the fuel electrode diffusion layer 4 and is arranged to have a comb-shaped structure that becomes a flow path 8 for each reaction gas flow. In many cases, a cooling water flow path is provided on the surface facing this surface. The oxidant gas and the fuel gas first pass through the reaction gas flow path 8 of the separator 5. While passing through the flow path 8, the reaction gas is supplied to the membrane electrode assembly 10 through the diffusion layer 4.

  As described above, the membrane electrode assembly 10 and the fuel cell including the membrane electrode assembly 10 according to the embodiment of the present invention have been described. However, the membrane electrode assembly 10 is not applied only to the fuel cell. Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

  As a catalyst layer slurry, platinum-supported carbon (TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) and water are mixed, and then 2-propanol and an electrolyte (Nafion dispersion, manufactured by Wako Pure Chemical Industries, Ltd.) are added and stirred. What was obtained was used. Each mixing mass ratio was set to 1: 3: 15: 2. Spray method using Nafion 211CS (manufactured by DuPont) as the electrolyte membrane 2, the fuel electrode catalyst layer 6 on one side, the air electrode catalyst layer 7 on the other side facing this, and the slurry. And by drying in an oven at 80 degrees Celsius. Both the catalyst layers 6 and 7 were 50 mm × 50 mm in size and formed in a strip shape with an interval of 100 mm.

As shown in FIG. 3, the long electrolyte membrane 2 is parallel to the belt-shaped region α where the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 are formed at a distance (g) from each other. Then, the PET film 1 with an adhesive layer 1 (width (w) 5 mm, thickness (h) 0.2 mm, peel adhesion strength 0.1 N / cm) was attached to both surfaces of the electrolyte membrane 2 as a spacer 1, 1 membrane electrode assembly 10 was produced.

  As shown in FIG. 4, the spacer 1 in Example 1 is not formed into a strip shape (width (w) 5 mm, length (m) 10 mm), and is 1 mm from the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7. After placing (g), the membrane electrode assembly 10 of Example 2 was fabricated by pasting on both surfaces of the electrolyte membrane 2 at an interval (n) of 10 mm.

  As shown in FIG. 5, an opening of 50 mm × 50 mm is formed in the long electrolyte membrane 2 (same as Example 1) having the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 formed on both sides, as shown in FIG. A PET film with an adhesive layer having an outer dimension of 150 mm width (at a thickness of 0.2 mm and a peel adhesion strength of 10 N / cm) having an interval of 100 mm was pasted so that the positions of the openings and the bipolar catalyst layers 6 and 7 were aligned. .

  Subsequently, in the same manner as in Example 1, the adhesive film-attached PET film 1 was bonded to both surfaces of the electrolyte membrane 2 to produce a membrane electrode assembly 10 of Example 3 shown in FIG. The catalyst layer was produced in the same manner as in Example 1.

<Comparative Example 1>
In the same Nafion 211CS as the electrolyte membrane used in Example 1, as in Example 1, the fuel electrode catalyst layer 6 and the air electrode catalyst layer 7 on the other surface are formed in a size of 50 mm × 50 mm at intervals of 100 mm. And the membrane electrode assembly of the comparative example 1 which does not provide a spacer was produced by drying in a 80 degreeC furnace.

<Comparative example 2>
A membrane / electrode assembly of Comparative Example 2 having a configuration in which the spacer 1 was removed from the configuration of the membrane / electrode assembly of Example 3 provided with the gasket member 3 was formed.

<Vibration test>
Ten membrane electrode assemblies thus prepared were stacked, and using a vibration tester (F-200BM / A-E04 manufactured by Emic Co., Ltd.), acceleration was 5G, sweep frequency was 10 to 55 Hz, left and right, depth direction, and vertical direction for 30 minutes each. Vibration was applied.

<Observation>
After the vibration test, the surface of the catalyst layer was observed. Compared to before vibration test,
○: No change was observed. ×: Thin portions and peeling were observed in the catalyst layer after the experiment as compared to before the experiment.

<High potential (OCV) holding durability test>
After the vibration test, diffusion layers (SIGRACE 35BC, SGL) were arranged on both surfaces of the membrane electrode assembly from which the spacer was peeled off, and a durability test was performed using a Japan Automobile Research Institute (JARI) standard cell. The cell temperature was 100 ° C., and humidified hydrogen was supplied to the fuel electrode and humidified oxygen was supplied to the air electrode. For the result X measured without the vibration test,
○: When the average value of 10 sheets is equal to or higher than X ×: When the average value of 10 sheets is lower than X

  The aforementioned vibration test was performed on the membrane electrode assemblies of Examples and Comparative Examples. Thereafter, the membrane electrode assembly of Example 1 and Comparative Example 1 was subjected to observation and high potential (OCV) holding durability test. The membrane electrode assemblies of Examples 2 and 3 and Comparative Example 2 were only observed.

スペーサ１を有する実施例１は触媒層の破損は見られなかったが、スペーサ１を有さない比較例１では触媒層の破損が見られた。実施例１は揺れ実験を施しても耐久性が維持されたが、比較例１は揺れ実験後の測定で耐久性が降下した。

In Example 1 having the spacer 1, the catalyst layer was not damaged, but in Comparative Example 1 having no spacer 1, the catalyst layer was damaged. The durability of Example 1 was maintained even when the shaking experiment was performed, but the durability of Comparative Example 1 was lowered by the measurement after the shaking experiment.

  In Example 2 with different shapes and numbers of spacers 1 on the film plane, the state of the catalyst layer did not change even after the shaking experiment.

  From these facts, it was confirmed that the membrane electrode assembly 10 according to the present invention was not damaged by the catalyst layer and the shape of the spacer was not damaged when it was laminated and subjected to vibration.

  Further, in Comparative Example 4 where only the gasket was attached, the catalyst layer was damaged, and in Example 3 where the gasket and the spacer 1 were attached, the catalyst layer was not damaged. From this, it became clear that the gasket surrounding the catalyst layer does not perform the function of protecting the catalyst layer, but it is effective to provide the spacer 1 on this gasket.

  From the above, it was shown that the membrane electrode assembly 10 according to the present invention is effective for protecting the fuel electrode and the air electrode during transportation and storage.

DESCRIPTION OF SYMBOLS 1 ... Spacer 2 ... Electrolyte membrane 3 ... Gasket member 4 ... Diffusion layer 5 ... Separator 6 ... Fuel electrode catalyst layer 7 ... Air electrode catalyst layer 8 ... Gas flow Path 10 ... Membrane electrode assembly

Claims (5)

An electrolyte membrane, a fuel electrode catalyst layer formed on one surface of the electrolyte membrane, and an air electrode catalyst layer formed on the other surface of the electrolyte membrane facing the fuel electrode catalyst layer , and , the surface of the anode catalyst layer and the cathode catalyst layer is provided with not the electrolyte membrane, a membrane electrode assembly Ru includes a gasket member,
The electrolyte membrane has an elongated shape having a certain width,
The fuel electrode catalyst layer and the air electrode catalyst layer are provided at an interval with respect to the longitudinal direction of the electrolyte membrane,
A spacer is provided on the first surface which is the surface opposite to the surface on the electrolyte membrane side of the gasket member ,
An adhesive layer is provided on the surface of the spacer facing the gasket member ;
A diffusion layer is provided on the opposite side of the fuel electrode catalyst layer and the air electrode catalyst layer from the electrolyte membrane,
The surface opposite to the surface on the electrolyte membrane side of the diffusion layer is the second surface,
The first surface of the gasket member and the second surface of the diffusion layer are flush with each other;
The membrane electrode assembly, wherein the spacer protrudes from the second surface .   The membrane electrode assembly according to claim 1, wherein the spacer is detachable.   The membrane electrode assembly according to claim 1 or 2, wherein the spacer is partially provided.   The thickness of the said spacer is 200 micrometers or more, The membrane electrode assembly as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   The spacer is provided in a band shape with a gap from the fuel electrode catalyst layer or the air electrode catalyst layer, and the gap is 0.5 mm or more and 10 mm or less with respect to the short direction of the electrolyte membrane. The membrane electrode assembly according to any one of claims 1 to 4.

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