JP2002141080A - Planar array electrochemical element unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planer array electrochemical unit with which designing freedom is enhanced by prevention of mixture of hydrogen gas and oxygen through securing of gas sealing property of individual power generating elements, and yet, hydrogen gas does not always have to be supplied in power generation. SOLUTION: A plurality of power generating elements 2A to 2E composed of an oxygen electrode layer 3, a proton conductive layer 5, and a hydrogen electrode layer 4 in a laminated structure are provided in series, of which, one power generating element is arrayed almost on the same plane with another adjacent one orthogonally to the laminated direction. The generating elements are arrayed alternately in an opposite direction, while, as for each element, the hydrogen electrode layer is structured with a hydrogen storage body provided with a first face 4A and a second face 4B parallel with and opposite to each other extending toward the layer direction, the proton conductive layer covers whole surfaces 5A, 5B, 5C, 5D of a hydrogen storage electrode including the first and the second faces, and the oxygen electrode layer is arrayed on the side of the first face 4A in contact with the outer surface of the proton conductive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical element unit, and more particularly, to a planar array type electrochemical element unit in which a plurality of solid polymer type power generating elements are connected in series adjacent to each other in a plane.

[0002]

2. Description of the Related Art A power generating element represented by a fuel cell utilizes electric energy among electric energy and heat energy generated by an electrochemical reaction for producing water from hydrogen and oxygen. The solid polymer type uses a solid polymer electrolyte membrane of a proton conductor layer. Both the hydrogen electrode layer and the positive electrode oxygen electrode layer are arranged with the proton conductor layer interposed therebetween, and hydrogen gas and the like as fuel are supplied to the hydrogen electrode layer side, and air or oxygen is supplied to the oxygen electrode layer side to supply electricity. Electric power can be extracted by causing a chemical reaction.

Since a single power generating element generates a small amount of power, a plurality of power generating elements are connected in series to obtain a desired power. Here, a planar array-type electrochemical element unit in which a plurality of power generating elements are connected adjacent to each other in a planar manner has a vertical, horizontal, and height like a stack structure in which a plurality of power generating elements are stacked and arranged. In contrast to the structure with some dimensions, the vertical and horizontal dimensions are emphasized, so no space in the height direction is required, miniaturization can be achieved, and This is advantageous in that the degree of freedom of mounting is increased.

For example, in an electrochemical device unit described in Japanese Patent Application Laid-Open No. 4-206162, two insulating plates are arranged in parallel with each other, and an oxygen electrode layer, a proton conductor layer, and hydrogen are disposed between the insulating plates. A plurality of power generating elements having a laminated structure with the electrode layer are connected in series. Here, a layer of one power generation element adjacent to the plurality of power generation elements and a layer of another power generation element are arranged on substantially the same plane in a layer direction orthogonal to the lamination direction, and specifically, The hydrogen electrode layer of one power generation element is arranged in the same plane as the hydrogen electrode layer of the adjacent power generation element. In order to supply fuel such as hydrogen gas to the hydrogen electrode layer, a hydrogen supply groove is formed in the insulating plate on the hydrogen electrode layer side. Further, in order to cool and humidify the proton conductor layer, water supply grooves are formed alternately with the hydrogen supply grooves in the insulating plate on the hydrogen electrode layer side. On the other hand, an oxygen supply groove is formed in the insulating plate on the oxygen electrode layer side.

[0005]

However, in the conventional planar arrangement type electrochemical element unit, one side of the planar arrangement is always hydrogen in order to reliably separate hydrogen gas, which is a fuel gas, from oxygen. Since it is necessary to use a gas passage and the other surface as an oxygen or air passage, the degree of freedom in design is limited.

In the conventional planar array type electrochemical element unit, it is necessary to strictly control the sealing of the hydrogen gas in the gas supply passage in the insulating plate. Since bending of the insulating plate causes hydrogen gas leakage, it is necessary to increase the rigidity of the insulating plate sufficiently to prevent bending.

Further, in order to connect adjacent power generation elements in series, it is necessary to cross connection cables within a pair of insulating plates, which complicates the structure. Further, during power generation, it is necessary to supply a hydrogen gas by constantly connecting a fuel supply device provided outside the planar array type electrochemical unit to a hydrogen supply path.

Therefore, the present invention can increase the degree of freedom in design by ensuring gas sealing properties of individual power generating elements and preventing mixing of hydrogen gas and oxygen, and constantly supply hydrogen gas during power generation. It is an object of the present invention to provide a planar array type electrochemical unit which does not need to be performed.

[0009]

In order to achieve the above object, the present invention provides a power generation element having a laminated structure of an oxygen electrode layer, a proton conductor layer, and a hydrogen electrode layer, which are provided in series, In the planar array type electrochemical element unit in which the layer of one adjacent power generation element and the layer of another power generation element are arranged on substantially the same plane in a layer direction orthogonal to the lamination direction, The hydrogen electrode layer is constituted by a hydrogen storage electrode having a first surface and a second surface which are opposed to each other in parallel and extend in the direction of the layer.
And covering the entire surface of the hydrogen storage electrode including the surface and the second surface, wherein the oxygen electrode layer is disposed on either the first surface or the second surface, and contacts the outer surface of the proton conductor layer. There is provided a planar array type electrochemical element unit provided in contact therewith.

Here, it is preferable that the hydrogen storage electrode is made of a hydrogen storage body made of any of carbon-based fullerene, nanotube, nanofiber, or metal hydride. The metal hydroxide is specifically made of a hydrogen storage alloy.

Preferably, the proton conductor is formed of an electrolyte membrane which does not require water management.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A planar array type electrochemical unit according to a first embodiment of the present invention will be described with reference to FIG. The planar array type electrochemical unit 1 includes an oxygen electrode layer 3
, And a plurality of power generation elements 2A to 2E having a laminated structure of the proton conductor layer 4 and the hydrogen electrode layer 5 are provided. Specifically, the power generation element 2A includes an oxygen electrode layer 3 extending in one direction X, a first surface 4A extending parallel to the one direction X, and a second surface 4A.
A hydrogen electrode layer 4 having a substantially rectangular cross section having a surface 4B, and a proton conductor layer 5 abutting on the oxygen electrode layer 3 and surrounding the hydrogen electrode layer 4 are provided. The proton conductor layer 5 includes an oxygen electrode layer-side portion 5A that is in contact with the oxygen electrode layer 3 and is located on the first surface 4A side and an electrically conductive portion 5B that is located on the second surface side of the hydrogen electrode layer 4. The portions 5C and 5D extending in the thickness direction of the hydrogen electrode layer 5 cover the entire cross section of the rectangular hydrogen electrode layer 4 and seal the hydrogen electrode layer 4 therein.

An electrical connection layer 6 is provided in contact with the oxygen electrode layer 3 and constitutes a positive electrode terminal 6A.
The electrical connection layer 6 is made of a gas-permeable porous material, and is configured to allow external air to flow to the adjacent oxygen electrode layer 3.

The electrically conductive portion 5B of the proton conductor layer 5 includes an electrical connection layer 7 made of a gas-impermeable non-porous material, and a gas-permeable porous layer in contact with the electrical connection layer 7. An electrical connection layer 8 made of a material is provided.
In the electrical connection layer 7, a plurality of leads 7A are formed so as to penetrate the electrical conduction portion 5B. The electrical connection layer 8 extends to the length of the adjacent power generation element 2B, and is in layer contact with the oxygen electrode 3 of the adjacent power generation element 2B. The adjacent power generation element 2B has the same configuration as the power generation element 2A, but in the opposite direction in the stacking direction, and sequentially from the top, the oxygen electrode layer 4, the oxygen electrode layer side portion 5A, the hydrogen electrode layer 4, The electrically conductive portion 5B, the electrical connection layer 7, and the electrical connection layer 8 are formed. Then, the electric connection layer 8 is connected to the adjacent power generation element 2.
It extends to the length of C, and is in contact with the oxygen electrode 3 of the adjacent power generation element 2C in the same manner as the relation with the first power generation element 2A. Hereinafter, the power generating element 2D is in the same direction as the power generating element 2B, and the power generating element 2E is provided in the same direction as the power generating elements 2A and 2C. That is, the adjacent power generation elements are arranged in opposite directions, and the layer of one adjacent power generation element and the layer of another power generation element are arranged on substantially the same plane in a layer direction orthogonal to the stacking direction. . The electrical connection portions 6, 8, 8A, 8B, 8C extending between the adjacent power generation elements are connected in series, and the electrical connection layer 8D of the last power generation element 2E is formed.
Abuts on the electrically conductive portion 5B, and its end is extended to form a negative electrode terminal 8E.

Here, the hydrogen electrode layer 4 is composed of a platinum catalyst and a hydrogen storage material made of either carbon-based fullerene, nanotube or nanofiber, and forms a hydrogen electrode as a whole. The hydrogen storage body stores hydrogen supplied from the outside into the inside thereof, and forms a hydrogen electrode as a whole. Each of the power generating elements 2A to 2E is provided with a hydrogen gas supply unit (not shown) for appropriately supplying hydrogen gas to the hydrogen storage when the amount of hydrogen stored in the hydrogen storage decreases. ing. Here, to occlude hydrogen internally does not necessarily mean occlusion of hydrogen molecules as they are, but occludes hydrogen supplied from the outside in a predetermined state according to the material constituting the hydrogen occlusion body. Means that.

The proton conductor layer 5 is made of a fullerene derivative material, specifically, a porous tube made of polyethylene (PE), polypropylene (PP), or polytetrafluoroethylene (PTFE). Is filled with a fullerene derivative-based proton conductor to form a solid membrane.
As described above, the proton conductor layer 5 is a solid membrane, and includes the oxygen electrode layer side portion 5A, the electrically conductive portion 5B,
Since the portions 5C and 5D cover the entire cross section of the rectangular hydrogen electrode layer 4, hydrogen gas can be sealed therein.
Hydrogen gas sealing performance of the power generating element alone can be ensured.

The fullerene derivative-based proton conductor used here is based on fullerene molecules forming spherical cluster molecules. Usually, C ₃₆ , C ₆₀ , C ₇₀ , C
₇₆ , C ₇₈ , C ₈₀ , C ₈₂ , C _84, etc., but in the present embodiment, C ₆₀ and C ₇₀ are selected. A fullerene derivative-based proton conductor is formed by introducing a proton dissociable group into a carbon atom constituting fullerene. Furthermore, by introducing an electron withdrawing group,
The proton dissociation of the group is further promoted. The proton dissociable group means a functional group from which a hydrogen ion (proton (H ⁺ )) can be eliminated by ionization, and includes —OH, —O
_{SO 3 H, -COOH, -SO 3} H, -OPO (OH)
₂ is preferred, but in the present embodiment, —OH or —OSO ₃ H is preferably used. In particular, a film formed of poly (fullerene hydroxide) having -OH as a proton dissociating group has a better film forming property than a film formed of a conventionally used perfluorosulfonic acid resin. Since no water molecules are required for proton conduction, a humidifier or the like is not required. Further, the operating temperature range is from -40 ° C to 16 ° C.
It has advantages such as a wide temperature of 0 ° C. and is suitable for the electrochemical device (fuel cell) of the present invention. Examples of the electron-withdrawing group include a nitro group, a carbonyl group, a carboxyl group, a nitrile group, a halogenated alkyl group, and a halogen atom (fluorine,
And any one or more of the above is selected and configured.

In the oxygen electrode 3, a catalyst layer made of carbon particles carrying platinum is impregnated with a fullerene derivative-based proton conductor. Since the oxygen electrode 3 is in contact with the electrical connection portion 6 made of a gas-permeable porous material,
Air in the atmosphere is supplied to the oxygen electrode 3 via the electrical connection 6, and oxygen contacts the catalyst in the oxygen electrode 3, is generated in the hydrogen electrode layer 4, and is generated through the proton conductor layer 5. Is generated from hydrogen ions, oxygen molecules, and electrons supplied from an external circuit (not shown). In addition, the generated water is supplied to the gas-permeable electric connection parts 6, 8, 8
It is possible to discharge through A, 8B and 8C.

As described above, in the planar array type electrochemical element unit 1 according to the first embodiment, the entire surface of the hydrogen electrode layer 4 of each power generation element is covered with the proton conductor layer 5. In addition, sealing of hydrogen gas can be achieved by the proton conductor layer 5 and gas sealing performance can be ensured by the power generating element alone, so that one surface side of the entire unit is hydrogenated like a conventional planar array type electrochemical element unit. There is no need to use the gas supply path as the air supply path on the other side, and the degree of freedom in design can be increased.

Since the hydrogen electrode layer 4 is composed of a hydrogen storage, a predetermined amount of hydrogen may be stored in the hydrogen storage, and hydrogen gas is constantly supplied to each power generating element for power generation. There is no need to supply.

A planar array type electrochemical device unit 10 according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that the power generating elements are all in the same direction, and that the electrical connection 18 has a crank shape. . In FIG. 2, each of the power generating elements 12A to 12E includes, from the bottom, an oxygen electrode layer 3, a portion 5A of the proton conductor 5 on the oxygen electrode layer side, a hydrogen electrode layer 4, and an electrically conductive portion 5B of the proton conductor 5. They are arranged in order. Further, the electrical connection layer 16 is the same as the electrical connection layer 6 of the first embodiment, but the electrical connection layers 18A to 18D are adjacent to each other, unlike the first embodiment. When viewed from a power generation element, the power generation element is formed in a crank shape so as to abut on the electrically conductive portion 5B of one element and the oxygen electrode layer 4 of the other element. The last electrical connection layer 18E includes a negative electrode terminal 18F, similarly to the electrical connection layer 8D in the first embodiment.

In the planar array type electrochemical element unit 10 according to the second embodiment, similarly to the first embodiment, the proton conductor 5 covers the entire cross section of the hydrogen electrode layer 4 made of a hydrogen storage material. As a result, a gas sealing property is ensured, and a structure having a high degree of freedom in design is provided while preventing mixing of hydrogen gas and air. In addition, since all the power generating elements are arranged in the same direction, all the water is discharged on the same side, which is convenient for water treatment.

A planar array type electrochemical device unit 20 according to a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the power generating elements 22A, 22B, 22C in which the oxygen electrode layers 3 are arranged on the
And the power generating elements 22D, 22E, and 22F in the same direction, in which the oxygen electrode layer 3 is arranged on the lower side, are arranged to face each other.
An electrical connection layer 26A similar to the electrical connection layer 16
Are provided in contact with the oxygen electrode 3 of the power generation element 22A to form a positive electrode terminal. Further, when the electric connection layers 28A, 28B are viewed from the adjacent power generation elements 22A, 22B, 22C, the crank shape is such that they contact the electrically conductive portion 5B of one element and the oxygen electrode layer 4 of the other element, respectively. Is formed. Further, the electric connection layer 28C is
Is formed in a U-shape so as to abut on the electrically conductive portion 5B of the power generation element 22D and the oxygen electrode layer 4 of the power generation element 22D immediately below the power generation part 5B. Then, when the electric connection layers 28D, 28E are viewed from the adjacent power generation elements 22D, 22E, 22F, the cranks are arranged so as to abut the electrically conductive portion 5B of one element and the oxygen electrode layer 4 of the other element, respectively. It is formed in a shape. Finally, the electric connection layer 28F is
A negative electrode terminal by contacting the electrically conductive portion 5B.

Also according to the third embodiment, the entire surface of the hydrogen electrode layer 4 of each power generating element is covered with the proton conductor layer 5, and sealing of hydrogen gas is achieved by the proton traditional body layer 5. As a result, gas sealing properties can be ensured by the power generating element alone. In addition, when the size of the place to be laid is limited in length and width, a stack-like layout is possible.

The planar array type electrochemical element unit according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims. For example, in the above-described embodiment, the hydrogen storage body itself constitutes the hydrogen electrode layer 4, but the hydrogen storage body does not have an electrode function, and the hydrogen storage body is surrounded by a separate hydrogen electrode. You may be able to do it. In this case, the separate hydrogen electrode is obtained by impregnating a catalyst layer made of carbon particles carrying platinum with a fullerene derivative-based proton conductor.
Since the fullerene derivative-based proton conductor is used as the ion conductor and is impregnated in the hydrogen electrode, the ion conduction in the electrode can be kept good even in a fuel-free state. Further, a fullerene derivative-based proton conductor can be adapted to the platinum catalyst.

The proton conductor layer of the planar array type electrochemical element unit according to the above-described embodiment is of a type in which a porous matrix is filled with a proton conductor.
A film type in which a resin-based binder is blended with the proton conductor may be used.

Further, in the planar array type electrochemical element unit according to the present embodiment, the proton conductor layer is formed by impregnating the porous substrate with the fullerene derivative-based proton conductor. A so-called internal humidification-type solid polymer film in which a very small amount of ultrafine platinum catalyst and ultrafine oxide particles such as TiO ₂ and SiO ₂ are highly dispersed inside the film, or a phosphoric acid-silicate (P ₂ O ₅₎ A polymer film to which a proton conductive inorganic compound such as —SiO ₂ ) glass is added may be used. By using these, as in the case of the element according to the present embodiment, it is not necessary to include moisture in the fuel with a humidifier or the like.

Further, in the present embodiment, poly (fullerene hydroxide) (commonly called fullerenol) is used as a proton conductor constituting an ion exchange membrane capable of conducting proton in a non-humidified state, but the present invention is not limited to this. It is not something to be done. The polyhydroxylated fullerene has a fullerene molecule as a matrix as shown in FIG. 4 and a hydroxyl group introduced into its constituent carbon atoms. The matrix is not limited to the fullerene molecule but may be a carbonaceous material mainly composed of carbon. Should be fine. This carbonaceous material includes carbon clusters, which are aggregates formed by bonding several to hundreds of carbon atoms regardless of the type of carbon-carbon bond, and tubular carbonaceous materials (commonly known as carbon Nanotubes). The former carbon clusters include spheres or spheroids composed of a large number of carbon atoms, or various similar carbon clusters having a closed surface structure similar thereto (FIG. 5), and a part of those spherical structures. Is missing and a carbon cluster having an open end in the structure (FIG. 6), a carbon cluster having a diamond structure in which most of the carbon atoms are sp ³ bonded (FIG. 7), and these clusters are variously bonded. Carbon clusters (FIG. 8) may be included.

The group to be introduced into the base of this type is not limited to a hydroxyl group, but may be any other proton-dissociable group represented by -XH, more preferably -YOH. Here, X and Y are arbitrary atoms or atomic groups having a divalent bond, H is a hydrogen atom, and O is an oxygen atom. Specifically, in addition to the -OH, a hydrogen sulfate ester group -OSO ₃
H, carboxyl group -COOH, and other sulfone group -SO
It is preferably any of ₃ H and a phosphorus group -OPO (OH) ₂ .

In any of the above-mentioned modifications, humidification is not required for proton conduction, and the effect of the present invention is not changed.

[0031]

According to the flat array type electrochemical element unit of the first aspect, the entire circumference of the hydrogen electrode layer made of the hydrogen storage material is surrounded by the proton conductor layer.
Hydrogen gas is sealed in the proton conductor layer and does not cause a problem of mixing with oxygen. Therefore, unlike the conventional planar array type electrochemical element unit, there is no need to separate the gas handled on one surface side and the other surface side of the unit, and the degree of freedom of design of the entire unit can be increased. it can.

Further, unlike the conventional planar array type electrochemical element unit, it is not necessary to form a gas supply groove in the insulating plate and strictly control the sealing of the gas in the gas supply path. In addition, the whole unit can tolerate a certain degree of bending, and the degree of freedom in laying can be increased.

According to the planar array type electrochemical element unit of the second aspect, since the hydrogen storage electrode using the hydrogen storage is used, a predetermined amount of the hydrogen gas source can be stored in the hydrogen storage. During the power generation operation, there is no need to connect an external device to the electrochemical element to supply hydrogen gas, and the device can function as a fuel cell that can be used for portable devices.

According to the planar array type electrochemical element unit of the third aspect, proton conduction can be performed without separately providing a humidifier.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a planar array type electrochemical element unit according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a planar array type electrochemical element unit according to a second embodiment of the present invention.

FIG. 3 is a side sectional view showing a planar array type electrochemical device unit according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a proton conductor used in the planar array type electrochemical element unit according to the embodiment of the present invention.
FIG. 3 is a molecular structure diagram showing fullerene.

FIG. 5 shows a proton conductor used in the planar array type electrochemical element unit according to the embodiment of the present invention;
Molecular structure diagram showing various carbon clusters having a spherical surface or a long sphere or a similar closed surface structure.

FIG. 6 is a diagram illustrating a configuration of a proton conductor used in a planar array type electrochemical element unit according to an embodiment of the present invention;
FIG. 2 is a molecular structure diagram showing a carbon cluster in which a part of a spherical structure is missing and an open end is present in the structure.

FIG. 7 constitutes a proton conductor used in the planar array type electrochemical element unit according to the embodiment of the present invention;
FIG. 3 is a molecular structure diagram showing a carbon cluster having a diamond structure in which most of the carbon atoms are SP3 bonded.

FIG. 8 constitutes a proton conductor used in the planar array type electrochemical element unit according to the embodiment of the present invention;
FIG. 4 is a molecular structure diagram showing a carbon cluster in which a plurality of clusters are variously bonded.

[Description of Signs] 1, 10, 20 Planar array type electrochemical units 2A to 2E, 12A to 12E, 22A to 22F Power generating element 3 Oxygen electrode layer 4 Hydrogen storage material 5 Proton conductor layer 6, 16, 26A Electrical connection Part 8, 8A to 8D, 18A to 18E, 28A to 28E Electrical connection

Claims (3)

[Claims] A plurality of power generating elements each having a stacked structure including an oxygen electrode layer, a proton conductor layer, and a hydrogen electrode layer are provided in series, and a layer of one adjacent power generating element and a layer of another power generating element are provided. However, in a planar array type electrochemical element unit which is arranged on the substantially same plane in a layer direction orthogonal to the lamination direction, for each power generation element, the hydrogen electrode layers face in parallel with each other and extend in the layer direction. The proton conductor layer covers the entire surface of the hydrogen storage electrode including the first surface and the second surface, and the oxygen electrode layer includes the hydrogen storage electrode having the first surface and the second surface. A planar array type electrochemical element unit, which is disposed on either the first surface or the second surface and is provided in contact with an outer surface of the proton conductor layer. 2. The planar arrangement according to claim 1, wherein the hydrogen storage electrode is made of a hydrogen storage body made of one of carbon-based fullerene, nanotube, nanofiber, and metal hydride. Type electrochemical element unit. 3. The flat array type electrochemical element unit according to claim 1, wherein the proton conductor is formed of an electrolyte membrane which does not require water management.