JP2016213157A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery which is high in installation stability, and has a high power generation quantity by using a member with good workability for a battery.SOLUTION: A fuel battery according to the present invention comprises a battery member. The battery member includes a first carbon nanotube of 100 nm or more in average diameter, and a second carbon nanotube of 30 nm or less in average diameter. The battery member has a structure in which the second carbon nanotube sticks to the surface of the first carbon nanotube, and the second carbon nanotube extends over pieces of the first carbon nanotube.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell.

  The carbon material has excellent performance in many aspects such as electrical conductivity, thermal conductivity, corrosion resistance, heat resistance, black colorability, and chemical stability. Therefore, it is used for various purposes. In particular, as a member for a fuel cell, various uses such as an electrode, a gas diffusion layer, and a current collector are conceived and attracts high attention.

  Carbon materials are often used in a state of being processed on a sheet. For example, Patent Literature 1 and Patent Literature 2 describe carbon felt (nonwoven fabric) including carbon fiber (PAN-based carbon fiber), carbon fleece, and the like.

  In addition, a sheet in which a carbon film is formed on a relatively hard resin or the like is also known.

Japanese Patent No. 3560181 International Publication No. 2014/033238

  However, it was difficult to obtain a battery member having high mounting stability and good workability, and it was difficult to obtain a fuel cell having a high power generation amount.

  For example, the carbon felt and the carbon fleece described in Patent Documents 1 and 2 have a very large volume change rate with respect to pressure. Therefore, high processing accuracy cannot be obtained, and mounting accuracy is lowered. Moreover, it is necessary to pack in a predetermined case, a fastener, packing, etc., compressing, and workability | operativity is very bad.

  A relatively hard carbon sheet has a small volume change rate. Therefore, it is necessary to process the carbon sheet into a size substantially the same as that of a predetermined case, fastener, packing, or the like. Since the carbon sheet is hard, it is relatively easy to process. However, it is difficult to realize this processing accuracy. Further, a gap is likely to be generated between the installed carbon sheet and the fitting portion. For this reason, there is a concern about the occurrence of leakage or the like when used as a battery member.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain a fuel cell having a high power generation amount by using a battery member having high attachment stability and high workability.

  As a result of intensive studies, the present inventors have found that a fuel cell member having high mounting stability and good workability can be obtained by using a carbon material in which two types of carbon nanotubes are mixed. And it discovered that the fuel cell which has a high electric power generation amount could be obtained by using this battery member, and completed invention.

  That is, this invention provides the following means in order to solve the said subject.

(1) A fuel cell according to an aspect of the present invention includes a first carbon nanotube having an average diameter of 100 nm or more and a second carbon nanotube having an average diameter of 30 nm or less, and the first carbon nanotube has a surface on the surface of the first carbon nanotube. A battery member having a structure in which two carbon nanotubes are attached and the second carbon nanotubes straddle a plurality of the first carbon nanotubes is used.

(2) In the fuel cell according to (1), the battery member may be used as an electrode.

(3) In the fuel cell according to (1), the battery member may be used as a gas diffusion layer.

(4) The fuel cell according to any one of (1) to (3) may be an air cell.

  A fuel cell and an air cell with large electromotive force can be realized.

The transmission electron micrograph of the member for batteries concerning one mode of the present invention is shown. It is a perspective schematic diagram of the member for batteries concerning one mode of the present invention. It is a schematic diagram for demonstrating the manufacturing method of the member for batteries. 1 is a schematic cross-sectional view of a polymer electrolyte fuel cell according to one embodiment of the present invention. It is a perspective schematic diagram of an air battery concerning one mode of the present invention. The result of having measured the compression displacement with respect to the load of the battery member of a dry state and an impregnation state is shown. The result of having measured the electric power generation characteristic of the air cell which respectively used the member for batteries of Example 2-1 and the carbon felt of Comparative Example 2-2 is shown.

Hereinafter, a fuel cell (air cell) to which the present invention is applied will be described in detail with reference to an example.
The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to them. A fuel cell other than an air cell (for example, a magnesium fuel cell, a microorganism, and the like) is not limited to the gist thereof. The fuel cell and the like, including a polymer electrolyte fuel cell, a direct oxidation fuel cell, a glucose fuel cell, a methanol fuel cell, etc.) can be appropriately modified and implemented.

(Battery materials)
FIG. 1 shows a transmission electron micrograph of a battery member used in one embodiment of the present invention. FIG. 2 is a schematic perspective view of a battery member used in one embodiment of the present invention. The battery member 10 includes a first carbon nanotube 1 having an average diameter of 100 nm or more and a second carbon nanotube 2 having an average diameter of 30 nm or less, and the second carbon nanotube 2 is attached to the surface of the first carbon nanotube 1. Thus, the second carbon nanotube 2 has a structure straddling the plurality of first carbon nanotubes 1.

  Since the second carbon nanotube 2 has a structure straddling the plurality of first carbon nanotubes 1, the battery member 10 can be maintained in its shape without being separated during the molding process. Further, since the second carbon nanotubes 2 straddle the first carbon nanotubes 1, the second carbon nanotubes 2 can fill the gaps between the first carbon nanotubes 1 that are mainly conductive. . That is, the conductivity of the battery member 10 can be increased.

  More preferably, the second carbon nanotube 2 has a structure entangled with the first carbon nanotube 1. When the second carbon nanotube 2 is entangled with the first carbon nanotube 1, the battery member 10 can easily maintain its shape. Further, the conductivity of the battery member 10 is further improved.

  Here, the “stretched structure” is sufficient if, for example, the second carbon nanotube 2 straddling the first carbon nanotube 1 can be confirmed when the battery member 10 is observed with a transmission electron microscope. For example, when arbitrary 100 second carbon nanotubes 2 are observed, preferably 10 or more, more preferably 50 or more second carbon nanotubes 2 straddle a plurality of first carbon nanotubes 1. It is sufficient if the structure can be confirmed. It is also possible to observe a plurality of locations and observe 100 second carbon nanotubes 2. For example, 10 second carbon nanotubes may be observed at 10 locations, and a total of 100 second carbon nanotubes may be observed.

  The first carbon nanotube 1 has an average diameter of 100 nm or more, preferably 100 to 1000 nm, and more preferably 100 to 300 nm. The second carbon nanotube 2 has an average diameter of 30 nm or less, preferably 1 to 30 nm, and more preferably 5 to 20 nm. The fiber lengths of the first carbon nanotube 1 and the second carbon nanotube 2 are preferably 1 to 100 μm.

  When the size of the first carbon nanotube 1 and the second carbon nanotube 2 is in the above range, the battery member 10 has a structure that can maintain high strength and high conductivity. This is because the first carbon nanotube 1 serves as a trunk and the second carbon nanotube 2 is suspended in a branch shape between the plurality of first carbon nanotubes 1. For example, if the average diameter of the first carbon nanotubes 1 is 100 nm or less, the trunk becomes unstable, causing problems such as cracks in the structure of the battery member 10, and it becomes difficult to maintain sufficient strength. On the other hand, if the average diameter of the second carbon nanotubes 2 is 30 nm or more, the branches become too rigid and difficult to bend, so that the second carbon nanotubes 2 can be sufficiently entangled with the first carbon nanotubes 1. Therefore, the conductivity is deteriorated.

  The average diameters of the first carbon nanotubes 1 and the second carbon nanotubes 2 are obtained by measuring the diameters of 100 or more fibers of the first carbon nanotubes 1 and the second carbon nanotubes 2 with an electron microscope. Each can be obtained as an average value.

  The second carbon nanotube 2 is contained in an amount of preferably 1 to 20 parts by mass, more preferably 4 to 17 parts by mass, and still more preferably 8 to 14 parts by mass with respect to 100 parts by mass of the first carbon nanotubes 1. If the 2nd carbon nanotube 2 is contained in this range, the electroconductivity of this battery member 10 will improve. This is because the second carbon nanotubes 2 are included in this range, so that the first carbon nanotubes 1 mainly function as a conductor, and further the second carbon nanotubes 2 are respectively connected to the first carbon nanotubes 1. This is thought to be an electrical connection between them to efficiently support conduction.

  The battery member 10 preferably contains a water-soluble conductive polymer. The water-soluble polymer is adsorbed on the surfaces of the carbon nanotubes (the first carbon nanotube 1 and the second carbon nanotube 2), and hydrophilizes the surface of the originally water-repellent carbon nanotube. By making the surface of the carbon nanotube hydrophilic, the battery member 10 is easily impregnated with the solvent. Hydrophilization can also be realized by introducing OH groups, COOH groups, etc. on the surface of the carbon material. In view of sufficiently hydrophilizing the inside of the battery member 10, it is particularly preferable to include a water-soluble conductive polymer in the battery member 10. When the battery member 10 has high hydrophilicity, there are advantages in that, when the battery member 10 is used in a solution, the proton mobility increases, the conductivity increases, and the electrolytic solution can be easily retained. . The reason why the conductivity is increased is that the electrolytic solution penetrates into the details of the electrode formed of the carbon nanotubes and efficiently causes the electrode reaction. Further, when the battery member 10 has high hydrophilicity, when the battery member 10 is used as a gas diffusion layer such as an air battery, the gas supplied from the outside through the battery member 10 can be dissolved in the electrolyte. It becomes easy.

  As the water-soluble conductive polymer, a conductive polymer having a sulfo group is preferable, and polyisothianaphthenesulfonic acid is more preferable. When the water-soluble conductive polymer has a sulfo group, it becomes a self-doped conductive polymer and can exhibit stable conductivity. In addition, since the sulfo group is also a hydrophilic group, it has an advantage of high affinity with an electrolyte when used as an electrode used in a solution. Among them, the isothianaphthene skeleton has a benzene ring and thus has π electrons, and polyisoisothianaphthene sulfonic acid is more preferable because of its high affinity with the π electrons of the skeleton of the carbon nanotube constituting the electrode.

The battery member 10 has a gap between the first carbon nanotube 1 and the second carbon nanotube 2. This gap is a small space because the diameters of the first carbon nanotube 1 and the second carbon nanotube 2 are very small. Therefore, the battery member 10 does not change much in volume even when a load is applied. That is, the battery member 10 has a hardness that can be processed with high processing accuracy in a dry state. Moreover, if the battery member 10 is hard, handling becomes easy. For this reason, it is possible to improve the attachment accuracy when attaching to a predetermined position.
Furthermore, the battery member 10 preferably includes carbon short fibers in order to easily obtain mechanical strength. The carbon short fibers in the battery member 10 are more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the total mass of the first carbon nanotubes 1 and the second carbon nanotubes 2.

Specifically, the volume change amount of the battery member 10 is such that the amount of compressive displacement when a load of 150 N / cm ² is applied in a dry state is 50% or less of the thickness in the direction in which the load is applied. preferable. If the amount of change in thickness in the direction in which a load is applied is within this range, workability during processing and workability during attachment can be performed with higher accuracy.

Further, the battery member 10 becomes soft when wet. Here, the wet means that the battery member 10 is impregnated with a solvent, or the electrode member 10 is filled with gas, but the humidity of the gas is 70% or more. .
Since the battery member 10 is hard in the dry state and soft in the wet state as compared with the dry state, the amount of compressive displacement at the time of pressurization differs between the dry state and the wet state. At a stage where a person works (processing, installation, installation work, etc.), the battery member 10 is dry. From the viewpoint of handling during work, the electrode member 10 is preferably hard. On the other hand, it is preferable that it is soft in terms of adhesion to the mounting portion and a surface that suppresses damage due to external force. The battery member 10 can obtain the ease of handling in the dry state and the adhesion to the mounting portion in the wet state because the amount of compression displacement at the time of pressurization is different between the dry state and the wet state.

  The battery member 10 preferably has a compressive displacement amount of 2.0 times or more when pressurized in a wet state relative to a compressive displacement amount when pressurized in a dry state. If the amount of compressive displacement at the time of pressurization in the wet state is 2.0 times or more than the amount of compressive displacement at the time of pressurization in the dry state, the high processing accuracy and mounting accuracy in the dry state and the wet state It is possible to further improve the accuracy of followability. In addition, handling during drying becomes easier and workability can be improved.

  The battery member 10 is preferably increased in volume by changing from a dry state to a wet state. That is, it is preferable that the battery member 10 swells. When the battery member 10 swells, the battery member 10 follows the shape of the case, fastener, packing, or the like to be incorporated. Therefore, the stability in the state which attached the member 10 for batteries to the battery can be made high.

For example, in the case of a carbon sheet having high hardness that is widely used in general, high processing accuracy can be obtained. However, since the shape does not change in a dry state or a wet state, sufficient followability with respect to the attachment location cannot be obtained. Therefore, it is difficult to realize a high power generation amount when the battery member 10 is used for a battery or the like.
Further, in the case of carbon felt or the like that is softer than the carbon sheet, high processing accuracy and mounting accuracy cannot be increased. Further, a reinforcing sheet is required when taking it into a battery or the like. Since this reinforcing sheet has poor conductivity as compared with carbon felt or the like, it causes deterioration of battery performance. Furthermore, since the volume change rate of carbon felt or the like is large, an operation of packing it in a predetermined position is necessary, and the workability is very poor.

(Method for producing battery member)
The method for manufacturing a battery member includes a step of producing a dispersion of carbon nanotubes and a step of processing the produced dispersion into a sheet.

  A process for producing a carbon nanotube dispersion will be described. A first carbon nanotube having an average diameter of 100 nm or more and a second carbon nanotube having an average diameter of 30 nm or less are prepared. These can be produced by known methods.

  The obtained first carbon nanotube and second carbon nanotube are dispersed in a solvent. At this time, it is preferable to add and disperse carbon short fibers as a structure. This solvent is preferably a conductive polymer aqueous solution. By using the conductive polymer aqueous solution, the carbon nanotubes are easily dispersed during mixing by a wet jet mill or the like described later. Although details are unknown, the surface of the battery member made of the material of the present invention is likely to be hydrophilic because the conductive polymer remains on the surface of the obtained battery member.

  The conductive polymer in the aqueous conductive polymer solution is preferably a conductive polymer having a sulfo group, more preferably a conductive polymer containing isothianaphthenesulfonic acid in the repeating unit, and polyisothianaphthenesulfonic acid. Is more preferable.

The amount of the conductive polymer to be added may be added in consideration of the following. That is, the conductive polymer may be added in an amount sufficient to make the carbon nanotubes hydrophilic and to improve dispersibility.
This can be confirmed by preliminary experiments. For example, the amount required for hydrophilization is greatly reduced even when carbon nanotubes are introduced into the aqueous conductive polymer solution. Don't say the amount.
The amount necessary for improving the dispersibility is, for example, when the surface roughness is measured and no conductive polymer is added when a battery member having a thickness of 200 μm is produced by the method described later. Is an amount that is 1/5 or less of the arithmetic average roughness Ra. More preferably, the amount is 1/10 or less. In particular, polyisothianaphthene sulfonic acid has a remarkable effect on hydrophilization and dispersibility improvement, and therefore, the addition amount may be extremely small. Therefore, in the case of polyisothianaphthenesulfonic acid, it is usually possible to disperse sufficiently by adding three times the amount necessary for hydrophilization.

  Carbon nanotubes tend to aggregate. Therefore, when the first carbon nanotube and the second carbon nanotube are dispersed in the solvent, it is preferable to disperse the solution in which the first carbon nanotube and the second carbon nanotube are added while applying a shearing force. As a method for applying the shearing force, a wet jet mill or the like is preferable. The wet jet mill is a method of passing through a narrow channel while applying high pressure to the solution. When passing through this narrow channel, a shearing force is applied to the first and second carbon nanotubes, and the dispersibility can be improved. The high dispersibility of the first and second carbon nanotubes increases the strength of the battery member. If the dispersibility is low, agglomerated grains are formed, and breakage is likely to occur therefrom. The short carbon fibers are preferably added after the second carbon nanotubes are dispersed, and again dispersed by a wet jet mill or the like.

  By using a wet jet mill, it is possible to disperse the second carbon nanotubes while suppressing damage to the first carbon nanotubes. The pressure during mixing is preferably 100 MPa or more, and more preferably 150 to 250 MPa. If it is the said range, a 2nd carbon nanotube can be disperse | distributed, suppressing the damage of a 1st carbon nanotube more notably.

Next, a battery member is produced from the produced dispersion containing carbon nanotubes. This process can be roughly created by papermaking.
For example, when producing a relatively small size, a liquid-permeable base material is installed in a stainless mesh having holes of about several mm. And a dispersion liquid is spread on this base material. Then, the solvent is discharged through the base material having liquid permeability and the holes of the mesh to obtain a battery member. At this time, the dispersion liquid supplied onto the substrate may assist the removal of the solvent by using a dryer or the like. This method is suitable when a small amount of electrodes having a relatively small area is produced. The thickness of the dispersion used at this time, the type of substrate, the shape, and the like can be the same as in FIG. 5 described later.

Further, from the viewpoint of mass productivity, it may be produced by a procedure as shown in FIG.
A prepared carbon nanotube dispersion 31 is dropped from a supply source 32 onto a substrate 11 having liquid permeability. Next, the dropped dispersion liquid 31 is coated using the coating means 33 so as to have a uniform thickness. As the coating means 32, a wire bar coater, knife coater, air knife coater, blade coater, reverse roll coater, die coater or the like can be used.

  The solvent 34 contained in the coated dispersion 31 passes through the substrate 11 having liquid permeability and is discharged from below. At this time, the removal of the solvent 34 may be assisted by using a dryer 35 or the like. The battery member 10 can be obtained by removing the solvent from the coated dispersion 31.

  At this time, the thickness of the dispersion 31 to be applied can be appropriately set with respect to the thickness of the obtained battery member 10. By examining the relationship between the thickness of the coating film and the obtained battery member in advance, a battery member having a desired thickness can be obtained.

  So far, the case where the battery member 10 is produced as a single unit has been described. In addition to this, the dispersion obtained in the step of preparing a dispersion of carbon nanotubes on the substrate is subjected to spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire The coating may be performed by a bar coating method, a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, an inkjet printing method, or the like. Thereafter, the solvent is removed from the coating film by drying or the like, and the battery member 10 in which the carbon nanotube layer is formed on the substrate can be obtained.

  The battery member 10 to be manufactured may be flat, or may have an uneven or bellows shape. The uneven or bellows battery member 10 is preferable because it has a large surface area and increases the surface area when used as an electrode. The battery member 10 having such a shape is manufactured by performing drying or pressurization on a mold having an uneven or bellows shape after removing moisture on the substrate. Can do.

It is preferable that the base material 11 is a thing which can permeate | transmit a solvent. Since the base material 11 can permeate the solvent, the solvent can be easily removed from the carbon nanotube dispersion. As the substrate 11, for example, a plastic film, paper, or the like can be selected as appropriate.
When used as the battery member 10, the base material 11 may be in close contact. The shape of the substrate is not particularly limited as long as a battery member can be provided on the surface thereof, and may be flat, or may have an uneven, bellows, or needle shape.

The base material 11 may be selected in consideration of the usage mode of the battery member 10. When a thinner and lighter material is required, it is preferable to use paper, a resin film, or the like. When non-conductivity is required, it is preferable to use a nonwoven fabric composed of glass fibers (glass paper), a nonwoven fabric composed of synthetic resin fibers such as aramid, polyester, nylon, vinylon, polyolefin and rayon. In addition, when acid resistance is required, a nonwoven fabric using fluorine resin, fluorine-based elastomer, polyester, acrylic resin, polyethylene, polypropylene, polyetheretherketone, polyimide, polyphenylene sulfide, or the like is more preferable. When oxidation resistance is required, a nonwoven fabric using a fluororesin, a fluoroelastomer, polyethylene, polyetheretherketone, polyphenylene sulfide, or the like is more preferable. When heat resistance is required, a non-woven fabric, a flame retardant film, a flame retardant paper or the like using a fluororesin, a fluorine elastomer, polyester, polypropylene, polyarylate, polyether ether ketone, polyimide, polyphenylene sulfide, or the like is preferable. When alkali resistance is required, a nonwoven fabric composed of aramid resin fibers is preferable.
In addition, although it is preferable that the base material at the time of using as the battery member 10 is the same as the base material 11 used at the manufacturing stage, it does not necessarily need to be the same.

  Although the example of water-soluble conductive polymer was demonstrated as a method of hydrophilizing the battery member 10, the method of hydrophilization is not restricted to this method, A well-known method can be used.

  In forming the battery member 10, an appropriate structure may be used at the same time to facilitate forming. For example, when the battery member 10 is formed, it may be formed together with conductive fibers, preferably carbon fibers, as necessary. In addition, you may shape | mold using additives, such as a catalyst metal and a binder, as needed.

(Fuel cell)
Next, how to incorporate the battery member 10 according to the present invention into an actual battery will be described. First, a polymer electrolyte fuel cell will be described as an example. FIG. 4 is a schematic cross-sectional view of the unit cell 100 of the fuel cell according to one aspect of the present invention. A unit cell 100 of a fuel cell includes an electrolyte membrane 101, a catalyst layer 102, a gas diffusion layer 103, and a separator 104. The unit cell 100 of the fuel cell has an electrolyte membrane 101 as a center, and a catalyst layer 102, a gas diffusion layer 103, and a separator 104 are sequentially arranged on both surfaces thereof.

Hydrogen gas is supplied to the anode side of the fuel cell. On the other hand, oxygen gas or air is supplied to the cathode side. As a result, a reaction of H ₂ → 2H ⁺ + 2e ⁻ occurs on the anode side. On the other hand, a reaction of 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O occurs on the cathode side. Thereby, electric energy can be taken out. These reactions occur in the vicinity of the catalyst supported on the catalyst layer 102. Therefore, the reaction does not proceed unless protons (H ⁺ ) generated on the anode side can be carried to the catalyst on the cathode side. The reaction does not proceed even if the supply of oxygen to the cathode and hydrogen gas to the anode is delayed.

Hereinafter, each member will be described in detail.
The electrolyte membrane 101 is a membrane that can carry protons generated on the anode side to the cathode side. On the other hand, the electrolyte membrane 101 inhibits conduction of the generated electrons. Therefore, the reaction on the anode side and the reaction on the cathode side can be separated.
As the electrolyte membrane 101, a known one can be used. For example, Nafion (registered trademark, manufactured by Sigma Aldrich) or the like can be used.

The catalyst layer 102 is disposed on both surfaces of the electrolyte membrane 101. A known material can be used for the catalyst layer 102. For example, platinum-supported carbon or the like can be used. Platinum functions as a catalyst for the reaction.
The aforementioned reaction occurs in the vicinity of the supported catalyst. Therefore, the catalyst layer 102 has proton conductivity in order to supply the generated protons to the vicinity of the catalyst. Protons are ions. Therefore, proton conductivity can be ensured by making the inside of the catalyst layer 102 into a liquid phase. At this time, the inside of the catalyst layer 102 means that, for example, when the catalyst layer 102 is made of platinum-supported carbon felt, a liquid exists in a gap between carbonaceous materials constituting the carbon felt. The gap does not need to be completely filled with the liquid, but may be present to the extent that protons can be conducted.

The gas diffusion layers 103 are disposed on the surfaces of the two catalyst layers 102 opposite to the electrolyte membrane 101, respectively. For the gas diffusion layer 103, the battery member 10 can be used.
The aforementioned reaction does not proceed when the supply of oxygen gas to the cathode side and hydrogen gas to the anode side stagnate. Therefore, gas is efficiently supplied to the catalyst layer 102 via the gas diffusion layer 103. The battery member 10 according to the present invention has a gap between the first carbon nanotube and the second carbon nanotube. Therefore, gas can pass through this gap and can function as the gas diffusion layer 103.

  The surface of the gas diffusion layer 103 (battery member 10) on the catalyst layer 102 side is preferably subjected to water repellent treatment. By performing the water repellent treatment, it is possible to prevent the liquid contained in the catalyst layer 102 from penetrating into the gas diffusion layer 103. Since the gas diffusion layer 103 needs to allow gas to pass therethrough, the inside thereof is preferably in a gas phase state. If the surface of the gas diffusion layer 103 is subjected to water repellent treatment, it is possible to prevent the liquid phase of the catalyst layer 102 from penetrating into the gas diffusion layer 103 even if the catalyst layer 102 and the gas diffusion layer 103 are in contact with each other. A known method can be used for the water repellent treatment. For example, water repellency can be expressed by applying a Teflon paint to a battery member. As another method, the battery member 10 can be exposed to a fluorine gas environment.

  The gas diffusion layer 103 supplies a reaction gas and also functions as a liquid supply source to the liquid phase in the catalyst layer 102. In the fuel cell, it is necessary to avoid that the catalyst layer 102 is dried and the liquid phase state cannot be maintained. Therefore, it is common to supply high-humidity gas via the gas diffusion layer 103. That is, the gas passing through the inside of the gas diffusion layer 103 is generally a gas but a gas in a high humidity state. Therefore, when the battery member 10 is used as the gas diffusion layer 103, the battery member 10 is in a wet state. Therefore, the battery member 10 incorporated in the position of the gas diffusion layer 103 in a dry state is wetted in the usage mode, and follows the shape of the incorporated case, fastener, packing, and the like. That is, when the battery member 10 according to the present invention is used as the gas diffusion layer 103, the structural stability during use can be further enhanced. Structural stability also contributes to improved power generation performance.

The separator 104 is disposed so as to cover the electrolyte membrane 101, the catalyst layer 102, and the gas diffusion layer 103. A gasket 105 may be provided in a portion where the separators 104 face each other. The separator 104 may be a known one, and may be made of a carbon material or a metal material. The separator 104 is formed with a groove 104A through which gas can flow.
The groove 104 </ b> A supports the gas supply to the catalyst layer 102 by the gas diffusion layer 103. By directing the gas flow in the thickness direction of the gas diffusion layer 103, the gas can be more efficiently supplied to the catalyst layer 102.

  In the fuel cell according to one embodiment of the present invention, the electrode member 10 according to the present invention is used as the gas diffusion layer 103. Therefore, the structural stability of the gas diffusion layer can be improved. Moreover, the processing accuracy at the time of attachment and attachment accuracy can be improved more. As a result, a fuel cell showing a high power generation amount can be realized.

(Air battery)
An air battery is an embodiment of a fuel cell. Hereinafter, how to incorporate the battery member 10 according to the present invention into an actual air battery will be described. FIG. 5 is a schematic perspective view of a single cell 200 of an air battery according to one embodiment of the present invention. In FIG. 5, the members are illustrated apart for ease of understanding, but these members are all in contact in actual use.
A single cell 200 of an air battery according to one embodiment of the present invention includes an electrolyte membrane 201, a first electrode 202, and a second electrode 203. You may have the support body 204 which supports the 2nd electrode 203. FIG.

  As the electrolyte membrane 201, any known membrane can be used as long as it can pass ions. For example, a filter paper in which an electrolytic solution is permeated may be used.

The first electrode 202 is a fuel electrode made of metal, and a known electrode can be used. For example, Mg, Li, Na, Ca, Al, Zn, etc. can be used. For example, when Mg is used as the first electrode 202, the reaction of 2Mg + 3OH ⁻ → 2Mg ²⁺ + 4e ⁻ occurs in the first electrode.

The second electrode 203 may have a conduction part 203A and a reaction part 203B. On the second electrode 203 side, oxygen gas in the air functions as a positive electrode active material. Therefore, a reaction of O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ occurs. In order to generate this reaction efficiently, it is preferable that the contact surface area between the second electrode 203 and the electrolyte membrane 201 is large. Therefore, the battery member 10 according to the present invention which can take a large surface area of contact with the electrolyte 201 and can pass a gas can be used for the electrode, particularly the reaction portion 203B. The battery member 10 according to the present invention has high conductivity even when compared with a conventional carbon felt or the like.

  For example, a mesh made of metal can be used for the conductive portion 203A. A battery may be formed by directly connecting a wiring to the reaction portion 203B, but the performance of the battery can be further improved by separately connecting to a substance having higher conductivity. Note that since the conductive portion 203A also needs to pass gas, it is preferable to perform processing that allows gas such as mesh to pass through.

  In order to advance the reaction via ions as described above, it is preferable that the gap inside the battery member 10 constituting the reaction part 203B is filled with a liquid. When the battery member 10 is wetted by the liquid, the strength is relatively lowered. For this reason, the second electrode 203 is preferably supported by the support 204. At this time, since it is preferable that the passage of gas is not hindered by the support 204, the support 204 is preferably provided with a hole 205 or the like.

  In the air battery according to one aspect of the present invention, the battery member 10 according to the present invention is used as a part of the electrode. Therefore, an air battery having higher conductivity and higher electromotive force than that of a conventional carbon felt or the like can be obtained.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

  Examples of the present invention will be described below. In addition, this invention is not limited only to a following example.

(Example 1-1)
Showa Denko VGCF (registered trademark) -H (average diameter 150 nm, average fiber length 10 μm) 900 g was used as the first carbon nanotube, and Showa Denko VGCF (registered trademark) -X (average diameter 15 nm) as the second carbon nanotube. , Average fiber length 3 μm) 100 g was used. Both of these were put in a solution in which 0.5 g of polyisothianaphthenesulfonic acid was dissolved in 50 liters of pure water, and preliminarily mixed using a mixer (ULTRA-TURRAX UTC 80 manufactured by IKA).

  The resulting mixture was treated at a pressure of 200 MPa using a wet jet mill (StarBurst HJP-25005, manufactured by Sugino Machine). 100 g of carbon short fibers (DonaCarbo Chop S-232, manufactured by Osaka Gas Co., Ltd.) was added to the resulting slurry as a structure, and mixed again using a wet jet mill (ULTRA-TURRAX UTC 80).

  Using 1.5 liters of this slurry mixed with carbon short fibers, the slurry was poured into a rectangular filter having a width of 210 mm and a length of 300 mm, and suction filtered to prepare a cake. The obtained cake was compressed by applying a total load of 20 tons, and a weight was placed on the cake and dried in a 200 ° C. drier. The dried cake had a thickness of 2.6 mm and a total mass of 28 g. The dried cake was cut into a size of 50 mm × 50 mm to obtain a battery member.

(Example 1-2)
A battery member was produced under the same conditions as in Example 1-1, except that 15 g of polyisothianaphthenesulfonic acid was dissolved and no carbon short fiber was added.

(Example 1-3)
A battery member was produced under the same conditions as in Example 1-1, except that 900 g of carbon nanotubes having an average diameter of 100 nm were used as the first carbon nanotubes.

(Example 1-4)
A battery member was produced under the same conditions as in Example 1-1, except that 100 g of carbon nanotubes having an average diameter of 30 nm were used as the second carbon nanotubes.

  When any of the electrode members in Examples 1-1 to 1-4 was observed with a transmission electron microscope, it was confirmed that the second carbon nanotube had a structure straddling between the plurality of first carbon nanotubes. In Example 1-1, as a result of observing a total of 100 second carbon nanotubes, 72 second carbon nanotubes 2 had a structure straddling a plurality of first carbon nanotubes 1.

(Example 2-1)
The battery member of Example 1-1 was cut out at 10 mm on each side. The thickness of the battery member was 2.6 mm.

(Comparative Example 2-1)
Carbon felt (KF30A) manufactured by Toyobo Co., Ltd. was cut out at 10 mm per side. The thickness of the carbon sheet was 3.3 mm.

  The compression displacement due to the load in the dry state and the compression displacement due to the load in the impregnated state of the battery member of Example 2-1 and the carbon felt of Comparative Example 2-1 were measured. The impregnated state means a state in which the battery member and the carbon felt are impregnated with water. The result is shown in FIG. In FIG. 6, the vertical axis represents the applied load, and the horizontal axis represents the amount of change in the thickness of the battery member or the carbon felt with respect to the direction in which the load is applied.

  As shown in FIG. 6, the battery member of Example 2-1 has a large displacement with respect to the load by impregnating the solvent. That is, it is understood that the battery member is softened by the impregnation and can cope with the deformation. On the other hand, the carbon felt of Comparative Example 2-1 shows no significant difference in the amount of displacement with respect to the load in either a dry state or an impregnated state. Further, the carbon felt of Comparative Example 2-1 has a large amount of displacement with respect to the load in the dry state. Therefore, the battery member of Example 2-1 can be processed with high accuracy in a dry state as compared with the carbon felt of Comparative Example 2-1, and can obtain high followability to the mounting position in a water-containing state. it can.

  Moreover, each of the battery member of Example 2-1 and the carbon sheet (TGP-H-90, manufactured by Toray Industries, Inc.) as Comparative Example 2-2 were used for the electrode (reaction unit 203B) of the air battery shown in FIG. The power generation characteristics were measured. Specifically, an air battery was assembled as follows and the power generation characteristics were measured. A support (acrylic plate 50 mm × 50 mm), electrode 202 (magnesium plate, diameter 30 mm), electrolyte membrane 201 (filter paper), electrode 203 (reaction part 203B (the battery member or the carbon sheet, both 20 mm × 20 mm), The conductive portion 203A (aluminum net)) and the support 204 (acrylic plate having a hole with a diameter of 18 mm) were stacked in this order to form an air battery cell. As the electrolytic solution, a 3 mass% sodium chloride aqueous solution was used. The result is shown in FIG. As shown in FIG. 7, it was confirmed that a high generated electromotive force could be obtained by using the battery member according to the present invention.

DESCRIPTION OF SYMBOLS 1 ... 1st carbon nanotube, 2 ... 2nd carbon nanotube, 10 ... Battery member, 31 ... Dispersion, 32 ... Supply source, 33 ... Coating means, 34 ... Solvent, 35 ... Dryer, 100 ... Fuel Batteries 101 ... electrolyte membrane 102 ... catalyst layer 103 ... gas diffusion layer 104 ... separator 104A ... groove 105 ... gasket 200 ... air battery 201 ... electrolyte membrane 202 ... first electrode 203 ... second Electrode, 203A ... conductive portion, 203B ... reactive portion, 204 ... support, 205 ... hole

Claims (4)

  A first carbon nanotube having an average diameter of 100 nm or more and a second carbon nanotube having an average diameter of 30 nm or less, wherein the second carbon nanotube is attached to a surface of the first carbon nanotube, and the second carbon nanotube A fuel cell comprising a battery member having a structure straddling between the plurality of first carbon nanotubes.   The fuel cell according to claim 1, wherein the battery member is an electrode.   The fuel cell according to claim 1, wherein the battery member is a gas diffusion layer.   The fuel cell according to claim 1, wherein the fuel cell is an air cell.