JP2011108423A - Fuel cell and method for manufacturing membrane electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly transfer CNT to an electrolyte membrane when using CNT for a catalyst layer of a fuel cell. <P>SOLUTION: The fuel cell includes: the electrolyte membrane; and the catalyst layers which are arranged both the sides of the electrolyte membrane so as to hold the electrolyte membrane therebetween. In the fuel cell, at least one of the catalyst layers comprises: a carbon nanotube; a catalytic metal supported on the carbon nanotube; and an electrolyte solution imparted to the circumference of carbon nanotube. The carbon nanotube is formed such that the area thereof contacting the electrolyte membrane is larger than the average area of cross section thereof with regard to the alignment direction of carbon nanotube. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell and a method for producing a membrane electrode assembly.

  For example, Patent Document 1 discloses that an electrode in which a catalytic metal is supported on a carbon nanotube (hereinafter referred to as “CNT”) is used as an electrode of a fuel cell. In the method of forming this electrode disclosed in Patent Document 1, first, CNT is grown on a substrate, and a catalytic metal and an ionomer are coated. The CNT electrode is attached to the electrolyte membrane at the tip of the CNT electrode opposite to the side in contact with the substrate. Next, this is hot pressed to join the electrolyte membrane and the CNT electrode, and then the substrate is peeled off. Thereby, an electrode is formed.

JP 2005-203332 A JP-A-2005-294109 JP 2004-030926 A

  However, when the CNT and the electrolyte membrane are joined by the method as described above, the binding force between the CNT and the electrolyte membrane may be weaker than the binding force between the CNT and the substrate. In this case, when the substrate is removed from the CNT after joining the CNT and the electrolyte membrane, the CNT is destroyed or the CNT electrode is not properly bonded to the electrolyte membrane side. It can happen that it is not transcribed.

  Accordingly, in order to solve the above problems, the present invention provides an improved fuel cell having a membrane electrode assembly in which CNTs are appropriately transferred to an electrolyte membrane, and a method for producing a membrane electrode assembly used in a fuel cell. It is to provide.

In order to achieve the above object, a first invention is a fuel cell,
An electrolyte membrane and a catalyst layer disposed on both sides of the electrolyte membrane across the electrolyte membrane,
At least one of the catalyst layers is
Carbon nanotubes,
A catalytic metal supported on the carbon nanotube;
An electrolyte solution applied around the carbon nanotube;
Including
The carbon nanotube is formed so that the area of the portion in contact with the electrolyte membrane is larger than the average area of the cross section with respect to the orientation direction of the carbon nanotube.

According to a second invention, in the first invention, the carbon nanotubes are:
In the portion not in contact with the electrolyte membrane, the electrolyte membrane has orientation in a direction perpendicular to the surface,
The portion in contact with the electrolyte membrane has orientation in a horizontal direction on the electrolyte membrane surface.

  According to a third aspect, in the first aspect, the average diameter of the cross section with respect to the orientation direction of the carbon nanotube is larger at the tip portion in contact with the electrolyte membrane than at other portions.

According to a fourth invention, in any one of the first to third inventions,
An electrolyte solution layer is formed on the electrolyte membrane surface,
The tip of the carbon nanotube is embedded in the electrolyte solution layer.

According to a fifth invention, in the first invention,
An electrolyte solution layer is formed on the electrolyte membrane surface,
The carbon nanotube is formed in a spiral shape toward the electrolyte membrane, and the tip of the carbon nanotube is embedded in the electrolyte solution layer.

According to a sixth invention, in the first invention,
An electrolyte solution layer is formed on the electrolyte membrane surface,
The carbon nanotube is formed in a wave shape toward the electrolyte membrane, and the tip of the carbon nanotube is embedded in the electrolyte solution layer.

A seventh invention is a method for producing a membrane electrode assembly of a fuel cell,
Growing carbon nanotubes on a substrate having a seed catalyst;
A step of supporting a catalytic metal on the carbon nanotube;
Applying an electrolyte solution around the carbon nanotubes;
A step of bonding an electrolyte membrane on the opposite side of the carbon nanotube from the portion to be bonded to the substrate, and transferring the carbon nanotube to the electrolyte membrane.
The step of growing the carbon nanotubes includes:
Growing the vicinity of the end opposite to the portion to be bonded to the substrate in a direction horizontal to the substrate;
Growing other parts in a direction perpendicular to the substrate;
Is provided.

The eighth invention is a method for producing a membrane electrode assembly of a fuel cell,
Growing carbon nanotubes on a substrate having a seed catalyst;
A step of supporting a catalytic metal on the carbon nanotube;
Applying an electrolyte solution around the carbon nanotubes;
A step of bonding an electrolyte membrane on the opposite side of the carbon nanotube from the portion to be bonded to the substrate, and transferring the carbon nanotube to the electrolyte membrane.
The step of growing the carbon nanotubes includes:
The diameter of the cross section of the end of the carbon nanotube opposite to the portion to be bonded to the substrate is made larger than the diameter of the cross section of the portion to be bonded to the substrate.

  According to the first invention, the carbon nanotubes of the catalyst layer are formed such that the area of the portion in contact with the electrolyte membrane is larger than the average area of the cross section with respect to the orientation direction of the carbon nanotubes. As a result, when the carbon nanotubes are transferred to the electrolyte membrane, a large binding force between the carbon nanotubes and the electrolyte membrane can be secured. Therefore, the destruction of the carbon nanotubes at the time of transferring the carbon nanotubes can be suppressed, and the carbon nanotubes in the catalyst layer of the fuel cell can be appropriately transferred.

  According to the second invention, the portion of the carbon nanotube in contact with the electrolyte membrane has an orientation in a horizontal direction with respect to the electrolyte membrane. Thereby, a large bonding area between the electrolyte membrane and the carbon nanotube can be ensured.

  According to the third invention, the average diameter of the cross section with respect to the orientation direction of the carbon nanotube is larger at the tip portion in contact with the electrolyte membrane than at the other portions. Thereby, the junction area of an electrolyte membrane and a carbon nanotube can be ensured more largely.

  According to the fourth invention, the electrolyte liquid layer is formed on the surface of the electrolyte membrane, and the tip of the carbon nanotube is embedded. Thereby, a large binding force between the electrolyte membrane and the carbon nanotube can be secured. Accordingly, the carbon nanotubes in the catalyst layer of the fuel cell can be appropriately transferred to the electrolyte membrane side.

  According to the fifth or sixth invention, the carbon nanotube is formed in a spiral shape or a wave shape toward the electrolyte membrane, and the tip portion thereof is embedded in the electrolyte solution layer. Thereby, a large binding force between the electrolyte membrane and the carbon nanotube can be secured.

  According to the seventh invention, the carbon nanotubes are grown in a direction perpendicular to the substrate and in a horizontal direction, respectively, and the tip of the carbon nanotube formed in the horizontal direction on the substrate is joined to the electrolyte membrane. And transcribe. Thereby, a large binding force between the carbon nanotube and the electrolyte membrane at the time of transfer can be secured, and the carbon nanotube can be appropriately transferred to the electrolyte membrane side.

  According to the eighth aspect of the invention, the carbon nanotube is formed such that the diameter of the cross section of the end opposite to the portion bonded to the substrate is larger than the diameter of the cross section of the portion bonded to the substrate. Is bonded to the electrolyte membrane to transfer the carbon nanotubes. Therefore, a large binding force between the carbon nanotube and the electrolyte membrane at the time of transfer can be ensured, and the carbon nanotube can be appropriately transferred to the electrolyte membrane side.

It is a schematic diagram for demonstrating the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer formation method of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer formation method of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer formation method of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer formation method of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer formation method of the fuel cell in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the catalyst layer of the fuel cell in Embodiment 2 of this invention. It is a schematic diagram for demonstrating the catalyst layer of the fuel cell in Embodiment 3 of this invention. It is a schematic diagram for demonstrating the catalyst layer of the fuel cell in Embodiment 4 of this invention. It is a schematic diagram for demonstrating the catalyst layer of the other fuel cell in Embodiment 4 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
[Configuration of fuel cell]
1 and 2 are schematic diagrams for illustrating a fuel cell according to Embodiment 1 of the present invention. FIG. 1 shows a membrane electrode assembly according to Embodiment 1 of the present invention. A plurality of membrane electrode assemblies shown in FIG. 1 are stacked, for example, via a separator to constitute a fuel cell.

  The membrane electrode assembly in FIG. 1 has an electrolyte membrane 2 that is a solid polymer electrolyte membrane. A cathode electrode catalyst layer 10 is formed on one surface side of the electrolyte membrane 2. A diffusion layer 12 is formed on the outside of the catalyst layer 10 (that is, on the side of the catalyst layer 10 opposite to the surface in contact with the electrolyte membrane 2). On the other hand, the surface of the electrolyte membrane 2 opposite to the surface on which the cathode electrode is formed is an anode electrode, the catalyst layer 14 is formed in contact with the electrolyte membrane 2, and further outside (in contact with the electrolyte membrane 2 of the catalyst layer 14). A diffusion layer 16 is formed on the side opposite to the surface.

  FIG. 2 schematically shows an enlarged part of the catalyst layer 10 (or 14). As shown in FIG. 2, the catalyst layer 10 has CNTs (carbon nanotubes) 102. The base part 102 b of the CNT 102 excluding the tip part 102 a in contact with the electrolyte membrane 2 has an orientation in a direction substantially perpendicular to the electrolyte membrane 2. The CNT 102 carries the electrocatalyst metal 104. Here, platinum is used as the electrode catalyst metal 104. A fluororesin ionomer 106 (electrolyte solution) is applied around the CNT 102. In the following description, the CNT 102 in a state where the electrocatalyst metal 104 is supported and the ionomer 106 is applied is also simply referred to as the CNT 102 unless otherwise required.

  By the way, the reaction at each electrode in the fuel cell proceeds by supplying fuel (or oxygen) to the reaction interface where the electrode catalyst metal 104 and the ion conductive material are in contact with each other. Therefore, in order for the electrode catalyst metal 104 to sufficiently function as a reaction field, the electrode catalyst metal 104 needs to be in contact with both the ion conductive material and the fuel (or oxygen). Also in the first embodiment, the size of the three-phase interface formed by the electrode catalyst metal 104, the ion conductive material and the fuel in the catalyst layer 10 (or 14) of the fuel cell affects the performance of the cell. It becomes an important factor.

  For this reason, in the first embodiment, the CNT 102 is used as a carrier for supporting the electrode catalyst metal 104 in order to ensure a large three-phase interface. Here, the CNT 102 is a single-layer or multilayer ultra-thin cylindrical substance, and is oriented vertically toward the electrolyte membrane 2 except for the tip 120a. As a result, the surface on which the electrode catalyst metal 104 is supported can be secured widely and the electrode catalyst metal 104 can be supported at a high density. Further, an ionomer 106, which is an electrolyte solution, is applied to the surface of the CNT 102 as an ion conductive substance. This ensures a wide three-phase interface.

[Characteristic configuration of the first embodiment]
In the catalyst layer 10 (14) of the first embodiment, the tip portion 102a, which is a portion in contact with the electrolyte membrane 2 of the CNT 102, is bent along the surface of the electrolyte membrane 2. That is, the CNT 102 is formed so as to have an orientation perpendicular to the electrolyte membrane 2 in the other part (base part 102 b), but the tip part 102 a is formed to bend 90 degrees with respect to it. The length of the tip 102a is 100 [nm] to 10 [μm]. On the other hand, the average diameter of the CNT 102 is 10 [nm] to 90 [nm]. With this configuration, the CNT tip portion 102 a is in contact with the electrolyte membrane 2 with an area wider than the area of the cross section perpendicular to the orientation direction of the CNT 102.

[Method of forming catalyst layer]
3 to 7 are diagrams for explaining a method of forming the catalyst layer 10 (14) of the fuel cell according to Embodiment 1 of the present invention. As shown in FIG. 3, first, the CNT 102 is grown on the substrate 30 supporting the seed metal by a plasma CVD (chemical vapor deposition) method. Specifically, first, as shown in FIG. 3A, a substrate 30 made of Si, SUS, Al or the like is disposed horizontally with respect to the plasma direction. In this state, the CNT 102 is grown by the CVD method. Since the CNT 102 grows in the plasma direction, the CNT 102 grows in a direction horizontal to the substrate 30 here. Here, the portion to be grown is the tip portion 102a of the CNT 102, and the length to be grown is 100 [nm] to 10 [μm].

  Next, as shown in FIG. 3B, the substrate 30 is rotated by 90 degrees. As a result, the substrate 30 is arranged perpendicular to the plasma direction. In this state, the CNT 102 is grown again by the plasma CVD method. Here, the CNTs 102 grow in a direction perpendicular to the substrate 30. The portion to be grown here is a portion that becomes the root portion 102b of the CNT 102, and the length to be grown is 10 [μm] to 200 [μm]. As described above, as shown in FIG. 3C, the CNT 102 having the root portion 102b and the tip portion 102a is formed.

  Next, as shown in FIG. 4, the electrode catalyst metal 104 is supported around the CNTs 102. Here, a platinum salt solution is dropped, dried and fired. As a result, platinum as the electrode catalyst metal 104 is supported on the entire CNT 102. Next, as shown in FIG. 5, the ionomer 106 is dispersed and dropped. Thereby, the ionomer 106 is applied around the CNT 102.

  As described above, the electrode catalyst metal 104 is supported, and the CNT 102 with the ionomer 106 applied is transferred to the electrolyte membrane 2. Here, as shown in FIG. 6, the substrate 30 is horizontal with respect to the electrolyte membrane 2, and the CNT tip portion 102 a side is in contact with the electrolyte membrane 2 and hot-pressed.

  Thereafter, as shown in FIG. 7, the substrate 30 is peeled off. As a result, the CNT 102 is thermally transferred to the electrolyte membrane 2 side. As a result, the catalyst layer 10 composed of the CNT 102, the catalyst metal 104, and the ionomer 106 is formed on the surface of the electrolyte membrane 2. The cathode and anode catalyst layers 10 and 20 are formed by the above-described methods.

  In general, CNT grown on a substrate is considered to have a relatively weak binding force with the substrate, and the dominant binding force when transferred by hot press is actually the binding force between the electrolyte membrane and the ionomer. It is thought that. For example, even when the CNT grows in the same direction (that is, the direction perpendicular to the substrate) to the tip as in the prior art, if the CNT is uniformly covered with the ionomer, the ionomer attached to the tip of the CNT It is considered that the binding force between the substrate and the electrolyte membrane is sufficiently larger than the binding force between the ionomer attached to the periphery of the CNT and the substrate at the joint between the substrate and the CNT, and therefore, transfer by hot pressing is performed.

  However, it is considered that the performance of the fuel cell is particularly improved when the weight ratio of ionomer to CNT is 3 or more. Assuming this specific gravity of 3, the ratio of the ionomer adhesion area at each of the CNT tip and the bonded portion of the substrate is considered to be 0.77. Therefore, it cannot be said that the adhesion area on the electrolyte membrane side is sufficiently large. For example, a lot of ionomers may adhere to the bonding portion side with the substrate due to variations in manufacturing, and the adhesion area may increase. Therefore, since the binding force between the electrolyte membrane and the tip portion may not be sufficiently large with respect to the binding force between the bonding portion and the substrate, the transfer may not be performed reliably.

  In this regard, in the first embodiment, the CNT tip portion 102a is formed to be bent longer than the average diameter of the CNT 102, thereby ensuring a large bonding area between the ionomer 106 and the electrolyte membrane 2 of the CNT tip portion 102a. 2 and the binding force between the CNTs 102 can be made larger than the binding force due to the ionomer at the joint between the substrate 30 and the CNTs 102. Therefore, according to the first embodiment, the CNT 102 is reliably transferred to the electrolyte membrane 2 while preventing the CNT 102 from being damaged or peeled off without being bound when the CNT 102 is transferred to the electrolyte membrane 2 side. Thus, the catalyst layer 10 (or 14) can be formed.

  In the first embodiment, the case where the CNT 102 having the bent tip portion 102a is used for each of the catalyst layers 10 and 20 formed on both sides of the electrolyte membrane 2 has been described. However, the present invention is not limited to this, and only one of the anode catalyst layer and the cathode catalyst layer may include the CNTs 102 described in the first embodiment. The same applies to the following embodiments.

  Further, the case where the CNT tip portion 102a is formed by rotating the substrate 30 with respect to the plasma direction has been described. However, in the present invention, the method of forming the CNT 102 in which the CNT tip 102a is bent is not limited to this. In the first embodiment, as long as a large contact surface with the electrolyte membrane 2 is ensured by bending the CNT tip 102a, the formation method may be another method.

  In the first embodiment, the case where the CNT 102 is oriented and grown by the plasma CVD method has been described. However, the present invention is not limited to this and may be formed by other methods. The same applies to the following embodiments. In the present invention, the length of the CNT tip portion 102a, the length of the root portion 102b, and the average diameter of the CNT 102 are not limited to the ranges described in this embodiment, and the length of the CNT tip portion 102a is not limited to the CNT 102. In other words, the CNT tip 102a may be formed so as to be in contact with the electrolyte membrane 2 in an area wider than the area of the cross section perpendicular to the orientation direction of the CNT 102.

  In the first embodiment, the case where platinum is used as the electrode catalyst metal 104 has been described. However, the present invention is not limited to this, and other metals may be used as long as they can function as an electrode catalyst metal. In addition, although the case where the fluororesin ionomer 106 is used as the electrolyte solution has been described, this may also use another ion conductive material. The same applies to the following embodiments.

  In the first embodiment, the case where the catalyst layer is applied to the polymer electrolyte fuel cell has been described. However, the present invention is not limited to this, and may be used for other types of fuel cells. The same applies to the following embodiments.

Embodiment 2. FIG.
FIG. 8 schematically shows an enlarged part of the catalyst layer of the membrane electrode assembly according to Embodiment 2 of the present invention. The catalyst layer 200 shown in FIG. 8 has the same configuration as the catalyst layer 10 shown in FIG. 2 except that the shape of the CNT 202 is different. In the following, parts different from the membrane electrode assembly of FIGS.

  As shown in FIG. 8, the CNT 202 of the catalyst layer 200 is formed such that the average diameter of the cross section with respect to the orientation direction of the tip end portion 202a is larger than the average diameter of the root portion 202b which is the other portion. Thereby, the contact surface of the electrolyte membrane 2 and the ionomer applied to the CNT tip portion 202a can be secured larger than that of the root portion 202b. Therefore, damage to the CNT 202 when the CNT 202 is transferred can be prevented.

  The CNT 202 in which the average diameter of the tip portion 202a shown in FIG. 8 is larger than the average diameter of the root portion 202b is formed, for example, by having a seed catalyst at the tip. In addition, the CNT formation method which has a seed catalyst in the front-end | tip is already known, and detailed description here is abbreviate | omitted. After the CNT 202 is formed, the electrode catalyst metal 204 is supported on the CNT 202, the ionomer 206 is applied, the substrate for forming the CNT 202 is peeled off, and the CNT 202 is transferred to the electrolyte membrane 2 in the same manner as the manufacturing method of FIGS. The

  As described above, the CNT 202 is formed so that the tip portion 202a has a larger diameter than the root portion 202b. Thereby, the binding force between the ionomer 206 applied to the periphery of the tip portion 202a and the electrolyte membrane 2 can be surely made larger than the fixing force between the ionomer around the bonded portion of the substrate and the CNT 202. Therefore, the catalyst layer 200 can be formed by reliably transferring the CNT 202 while suppressing the destruction of the CNT 202.

  Note that the method of forming the shape of the CNT tip 202a is not limited to the method using the seed catalyst as the tip. Any other method may be used as long as the diameter of the tip portion can be increased by other methods.

Embodiment 3 FIG.
FIG. 9 is an enlarged schematic view of a part of the catalyst layer 300 of the fuel cell according to Embodiment 3 of the present invention. The catalyst layer 300 in FIG. 9 has the same configuration as the catalyst layer 10 in FIG. 2 except that an ionomer is applied to the surface of the electrolyte membrane 2.

  Specifically, the catalyst layer 300 in FIG. 9 includes the CNT 302, the electrode catalyst metal 304 supported on the CNT 302, and the ionomer 306 provided around the CNT 302, as in the catalyst layer 10 in FIG. . Further, in FIG. 9, the catalyst layer 300 has a thick ionomer layer 308 (electrolyte solution layer) formed of the same ionomer as the ionomer 306 between the CNT 302 and the electrolyte membrane 2.

  Further, the method for forming the catalyst layer 300 in the third embodiment is the same as the method described with reference to FIGS. 3 to 7 except that the ionomer layer 308 is formed on the electrolyte membrane 2 before the transfer of the CNT 302.

  As described above, in the third embodiment, the ionomer layer 308 is formed on the surface of the electrolyte membrane 2, thereby improving the adhesion between the electrolyte membrane 2 and the CNT 302 during transfer and improving the transferability. Can do.

  In the third embodiment, the case where the ionomer layer 308 is formed on the surface of the electrolyte membrane 2 in order to improve transferability has been described. However, for example, instead of forming the ionomer layer 308, the ionomer may be selectively applied thickly to the CNT tip 102 (202) of the first or second embodiment. Even in this case, the binding force between the electrolyte membrane 2 and the CNT can be increased, and the CNT can be appropriately transferred to the electrolyte membrane 2.

  In this embodiment, the case where the ionomer 306 attached to the periphery of the CNT 302 and the ionomer of the ionomer layer 308 on the surface of the electrolyte membrane 2 are the same is described. However, the present invention is not limited to this. For example, an ionomer having a lower melting point than the ionomer 306 attached to the CNT 302 may be used as the ionomer of the ionomer layer 308 in order to improve adhesion.

  In the third embodiment, the case where the ionomer layer 308 is applied to the CNT 102 having the bent tip portion 102a of the first embodiment has been described. However, the present invention is not limited to this. For example, as shown in FIG. 8, an ionomer layer similar to that of the third embodiment is provided on the CNT 202 having the tip 202a having a large diameter, or the ionomer of the tip 202a is provided. Alternatively, only 206 may be applied thickly.

Embodiment 4 FIG.
FIG. 10 is an enlarged schematic diagram of the catalyst layer 400 according to Embodiment 4 of the present invention. The catalyst layer 400 shown in FIG. 10 has the same configuration as the catalyst layer 300 of FIG. 9 except that the shape of the CNTs is different. Specifically, the CNTs 402 of the catalyst layer 400 are formed in a spiral shape, and are arranged in a vertical direction as a whole with respect to the electrolyte membrane 2. By using the spiral CNT 402 in this way, the CNT tip end portion 402 a is embedded in the ionomer layer 408. As a result, an anchor effect is obtained, and a high binding property between the CNT 402 and the electrolyte membrane 2 can be secured during the transfer of the CNT 402. Accordingly, when the substrate 410 is peeled off during CNT 402 transfer, destruction of the CNT 402 can be prevented.

  In the fourth embodiment, the case where the CNT 402 is formed in a spiral shape has been described. However, the present invention is not limited to this. FIG. 11 is a diagram for explaining another example of the CNT used in the catalyst layer in the fourth embodiment. In the example shown in FIG. 11, the CNT 502 of the catalyst layer 500 is formed in a wave shape. Thus, even if it is formed in a wave shape, the tip end portion 502 a is embedded in the ionomer layer 510. Therefore, the anchor effect can be exerted, and a large amount of binding between the CNT 502 and the electrolyte membrane 2 can be ensured when the CNT 502 is transferred. Accordingly, damage to the CNT 502 can be suppressed, and the CNT 502 can be appropriately transferred to the electrolyte membrane 2.

2 Electrolyte membrane 12, 16 Diffusion layer 10, 14, 200, 300, 400, 500 Catalyst layer 102, 202, 302, 402, 502 CNT
102a, 202a tip 104, 204, 304, 404, 504, electrocatalyst metal 106, 206, 306, 406, 506, ionomer 308, 408, 508 ionomer layer 30, 410, 510 substrate

Claims (8)

An electrolyte membrane and a catalyst layer disposed on both sides of the electrolyte membrane across the electrolyte membrane,
At least one of the catalyst layers is
Carbon nanotubes,
A catalytic metal supported on the carbon nanotube;
An electrolyte solution applied around the carbon nanotube;
Including
The fuel cell, wherein the carbon nanotube is formed such that an area of a portion in contact with the electrolyte membrane is larger than an average area of a cross section with respect to an orientation direction of the carbon nanotube. The carbon nanotube is
In the portion not in contact with the electrolyte membrane, the electrolyte membrane has orientation in a direction perpendicular to the surface,
2. The fuel cell according to claim 1, wherein the portion in contact with the electrolyte membrane has an orientation in a horizontal direction on the electrolyte membrane surface.   2. The fuel cell according to claim 1, wherein an average diameter of a cross section with respect to the orientation direction of the carbon nanotube is larger at a tip portion in contact with the electrolyte membrane than at other portions. An electrolyte solution layer is formed on the electrolyte membrane surface,
The fuel cell according to any one of claims 1 to 3, wherein a tip portion of the carbon nanotube is embedded in the electrolyte solution layer. An electrolyte solution layer is formed on the electrolyte membrane surface,
2. The fuel cell according to claim 1, wherein the carbon nanotube is formed in a spiral shape toward the electrolyte membrane, and a tip portion of the carbon nanotube is embedded in the electrolyte solution layer. An electrolyte solution layer is formed on the electrolyte membrane surface,
2. The fuel cell according to claim 1, wherein the carbon nanotube is formed in a wave shape toward the electrolyte membrane, and a tip portion of the carbon nanotube is embedded in the electrolyte solution layer. Growing carbon nanotubes on a substrate having a seed catalyst;
A step of supporting a catalytic metal on the carbon nanotube;
Applying an electrolyte solution around the carbon nanotubes;
A step of bonding an electrolyte membrane on the opposite side of the carbon nanotube from the portion to be bonded to the substrate, and transferring the carbon nanotube to the electrolyte membrane.
The step of growing the carbon nanotubes includes:
Growing the vicinity of the end opposite to the portion to be bonded to the substrate in a direction horizontal to the substrate;
Growing other parts in a direction perpendicular to the substrate;
A method for producing a membrane electrode assembly of a fuel cell, comprising: Growing carbon nanotubes on a substrate having a seed catalyst;
A step of supporting a catalytic metal on the carbon nanotube;
Applying an electrolyte solution around the carbon nanotubes;
A step of bonding an electrolyte membrane on the opposite side of the carbon nanotube from the portion to be bonded to the substrate, and transferring the carbon nanotube to the electrolyte membrane.
The step of growing the carbon nanotubes includes:
A fuel cell membrane electrode, wherein a diameter of a cross section of an end portion of the carbon nanotube opposite to a portion bonded to the substrate is larger than a diameter of a cross section of a portion bonded to the substrate. Manufacturing method of joined body.

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