JP2004006374A - Electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electrochemical device excellent in electric characteristics with a mechanical strength and a chemical stability, yet fit for mass production. <P>SOLUTION: Gas diffusion electrodes 12, 13 composed of either a woven or a nonwoven fabric of a metal fiber are provided at either side of a solid polymer electrolyte 14. The gas diffusion electrodes may be of a combination of one or two or more kinds among a mixed-wool woven or nonwoven fabric of metal and organic fibers, a fluorinated metal fiber, one retaining catalyst particles, and a metal fiber plated with another metal. Further, the electrodes may be ones either divided, curved or equipped with a plurality of through-holes, and may be pinched by a collector with elasticity. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrochemical device having excellent mechanical strength and chemical stability, and more particularly to a fuel cell that generates electric power by utilizing an electrochemical reaction, a purifying apparatus that purifies a gas, a gas sensor that detects a gas, and the like. The present invention relates to an electrochemical device suitable for use.
[0002]
[Prior art]
An electrochemical device is a device that performs a basic reaction for generating power or purifying a gas by utilizing an electrochemical reaction, and is widely applied to a fuel cell, a gas purification device, a gas sensor, and the like. ing. For example, in a fuel cell, chemical energy is directly converted into electric energy by supplying fuel to one of the electrodes in contact with both surfaces of the electrolyte body and an oxidizing agent to the other, and electrochemically reacting the oxidation of the fuel in the cell. In the case of a polymer electrolyte fuel cell, for example, it refers to a solid polymer membrane as an electrolyte and a gas diffusion electrode, or an integrated product thereof.
[0003]
FIG. 16 is a sectional view of an electrochemical device 1 constituting a typical proton conductive solid polymer electrolyte fuel cell. In the figure, 2 is a solid polymer electrolyte membrane (hereinafter abbreviated as an electrolyte membrane), 3 is an anode electrode, and 4 is a cathode electrode. The electrolyte membrane 2 is a perfluorosulfonic acid membrane, and the anode electrode 3 and the cathode electrode 4 are each made of a carbon fiber carrying a platinum catalyst.
Next, the operation will be described. When hydrogen gas is supplied to the anode electrode 3 and oxygen is supplied to the cathode electrode 4 and current is taken out from the anode electrode 3 and the cathode electrode 4 through an external circuit, the following reaction occurs.
Anode reaction
H ₂ → 2H ⁺ + 2e ⁻ ・ ・ ・ ・ ・ (1)
Cathodic reaction
2H ⁺ + 2e ⁻ + 1 / 2O ₂ → H ₂ O ... (2)
At this time, hydrogen becomes a proton on the anode electrode 3, moves along with the water through the electrolyte membrane 2 to the cathode electrode 4, and reacts with oxygen on the cathode electrode 4 to generate water. Therefore, when this reaction occurs, gas and liquid water flow in and out of the pores of the electrode, and electrons flow in the base material of the electrode. Therefore, in order to carry out such a reaction smoothly, it is necessary not to hinder the transfer of the reaction active material generated or consumed by the reaction and to not hinder the transfer of the electrons. Regarding the movement of the active material, when water is a liquid, the flow of the reaction gas may be blocked by the liquid droplets, and the movement of the water is particularly important.
[0004]
For this purpose, as a method of promoting the movement of water by a mechanical force such as pressure or a channel structure, Japanese Patent Application Laid-Open Nos. Hei 1-309263, Hei 2-86071 and Hei 2-260371 have already been described. And Japanese Patent Laid-Open Publication No. 3-102774. Japanese Patent Application Laid-Open (JP-A) Nos. 1-140562, 3-149762, and 3-182052 disclose means for promoting the transfer of water using a desiccant or a hydrophilic material due to a difference in affinity with water. Proposed. Electrons are transferred by using a conductive material for the electrodes. Therefore, when manufacturing the electrodes, for example, as shown in JP-A-3-25856, a conductive carbon powder and a water-repellent material or There is a method in which a reinforcing agent is kneaded and bound, and as a method of binding a metal, Japanese Patent Application Laid-Open No. 2-152166 is proposed.
[0005]
There is also a method of supporting a weak electrode material with a rigid structure. For example, Japanese Patent Application Laid-Open No. 3-149762 has been proposed. Electrochemical devices have various uses. In addition to those described in the above patents, the gas purifying apparatus disclosed in Japanese Patent Publication No. 62-59184 and the dehumidifying apparatus disclosed in Japanese Patent Application Laid-Open No. 61-216714 may be used. Devices and the like have been proposed.
[0006]
[Problems to be solved by the invention]
Since the electrochemical devices used in conventional fuel cells and the like are configured as described above, the electrodes are mechanically brittle as a structure as described above, and when deformed, they may cause cracking or chipping. There was a problem that there was a risk of doing so.
[0007]
The present invention has been made in order to solve the above problems, and has as its object to obtain an electrochemical device which is excellent in electric characteristics and can be mass-produced while maintaining mechanical strength and chemical stability. And
[0008]
[Means for Solving the Problems]
In the electrochemical device according to the present invention, gas diffusion electrodes are provided on both sides of the solid polymer electrolyte, and the gas diffusion electrodes are bent to be integrated with the solid polymer electrolyte.
[0009]
In the electrochemical device according to the present invention, the gas diffusion electrode is either a mixed woven fabric or a mixed nonwoven fabric of metal fibers and organic fibers, and the metal fibers and the organic fibers have different hydrophilicity.
[0010]
In the electrochemical device according to the present invention, the gas diffusion electrode is made of either a woven or non-woven metal fiber, and the metal fiber is fluorinated.
[0011]
(Function) In the electrochemical device according to the present invention, the gas diffusion electrode is bent and integrated with the solid polymer electrolyte, whereby the electrode area per unit area is increased, and the electrochemical reaction proceeds smoothly.
[0012]
In the electrochemical device according to the present invention, the gas diffusion electrode is made of either a mixed woven fabric or a mixed nonwoven fabric of metal fibers and organic fibers having different hydrophilicities, so that the gas diffusion electrode mechanically deforms the solid polymer electrolyte. In addition to preventing water, the water generated on the electrode is concentrated and concentrated on one fiber by the plural kinds of fibers with different hydrophilicity, and the other fiber creates a space where gas passes, and the gas required for the reaction reacts. The water easily flows into the part, and water required for the reaction can be easily supplied to the reaction part in a liquid state. Further, the electrode area per unit area is enlarged, and the electrochemical reaction proceeds smoothly.
[0013]
In the electrochemical device according to the present invention, the gas diffusion electrode is made of either woven or non-woven metal fiber, and the metal fiber is fluorinated, so that the gas diffusion electrode mechanically prevents deformation of the solid polymer electrolyte. At the same time, water repellency is imparted by fluorination, so that water generated on the electrode by the electrochemical reaction moves in a spherical shape in the space of the electrode base material, and gas required for the reaction flows into the reaction part. And the electrode area per unit area is increased, and the electrochemical reaction proceeds smoothly.
[0014]
Embodiment 1 FIG. FIG. 1 is a conceptual cross-sectional view of an electrochemical device 11 according to Embodiment 1 of the present invention. In the figure, reference numerals 12 and 13 denote metal fiber electrode base materials (gas diffusion electrodes), and reference numeral 14 denotes a solid polymer electrolyte membrane. . As a metal fiber, a single fiber of SUS316L having a diameter of 12 μm and a length of 50 to 100 mm was subjected to open fiber sintering and then sintered, and a basis weight of 400 g / cm. ² Cloth was used. When Nafion 117 manufactured by DuPont, which is a commercially available perfluorosulfonic acid membrane, is used as the solid polymer electrolyte membrane 14, the electrode substrates 12, 13 and the polymer membrane 14 are weighed at 190 ° C. at 50 kg / cm. ² When hot pressing was performed at the surface pressure of 1 to perform integration, the fibers of the electrode base materials 12 and 13 bit into the polymer film 14 by 50 μm.
[0015]
Next, the operation will be described. When this electrochemical device 11 is manufactured as an integrated product having a size of 10 cm square, even if only one end is handled by hand due to the steel property of the electrode base material, no separation or non-reproducible distortion is caused. Was. Further, the operation of immersing the electrochemical device 11 in water and then drying it in the air at 100 ° C. was repeated three times, but the electrode substrates 12 and 13 and the polymer film 14 were not separated at all and the shape did not change. Was. When this test was performed using a conventional electrode substrate, the electrode substrate was cracked and the substrate was peeled off. Further, when the electric resistance between the electrode base materials 12 and 13 of the present embodiment was examined, a low resistance was maintained during the immersion and drying. Since the polymer electrolyte membrane 14 itself expands and contracts depending on the water content, the adhesion between the polymer membrane 14 and the bases 12 and 13 is very strong in this test, and the strength of the metal fibers causes the polymer membrane 14 to adhere to the polymer membrane 14. It is considered that the deformation was prevented. Further, since the electric conductivity of SUS316L itself is about 10 times that of carbon, electrons in the base material can be smoothly moved, and the voltage loss can be kept low. If the diameter of the metal fiber is smaller than this time, the surface area per unit volume increases and the reaction area increases, but the gas permeation resistance increases. It is desirable to use a cloth. Conversely, those having a large fiber diameter can be used having a large basis weight. When the steel material of the electrode base material itself is not so required by tightening with a frame or the like, it is also possible to use a felt that does not perform sintering.
[0016]
Embodiment 2 FIG.
Hereinafter, a second embodiment of the present invention will be described.
This electrochemical device is obtained by fluorinating the metal fibers constituting the electrode bases 12 and 13 of the electrochemical device 11 of the first embodiment, and the shape and mechanical operation are the same as those of the electrochemical device of the first embodiment. It is the same as the device 11. The fluorination of the metal fiber cloth was performed by placing the fibers in a fluorine or hydrogen fluoride gas. Since metal fibers have a large reaction area unlike plates, the concentration of fluorine or hydrogen fluoride gas should be kept to a few percent or less, or the number of moles equal to the number of moles of the monoatomic layer on the metal fiber surface when vacuum is applied. It is desirable to gradually introduce the following reaction gas.
[0017]
Next, the operation will be described. When water is sprayed on the electrochemical device 11 of this embodiment, the water rolls on the electrode substrates 12 and 13 in a spherical shape. Therefore, even if water adheres to the apparatus using the electrochemical device 11, water does not enter the electrode bases 12 and 13, so that a space through which the gas passes is secured, and the reaction gas and the gas to be detected are provided. Is continuously supplied to the reaction section. Further, when water is generated by the reaction, the electrode substrates 12 and 13 have a property of repelling water by fluorination, so that the water generated by the reaction becomes spherical and is formed on the electrode substrates 12 and 13. And a large number of spaces are held in the electrode base materials 12 and 13, and the reaction gas can easily flow through the space. The reaction is smoothly carried out because it is continuously supplied to the interface with the substrates 12 and 13.
[0018]
Embodiment 3 FIG.
Hereinafter, a third embodiment of the present invention will be described. FIG. 2 is a schematic cross-sectional view of the electrochemical device 15 according to the third embodiment. In the figure, reference numerals 16 and 17 denote electrode substrates (gas diffusion electrodes), and reference numerals 21 and 31 denote metal fibers in the electrode substrates 16 and 17. , 22, and 32 indicate organic fibers in the electrode bases 16 and 17. Water-repellent fluorine-based fibers were used as the organic fibers 22 and 32, and hair was mixed at a weight ratio of 10% or less.
[0019]
Next, the operation will be described. When water is sprayed on the electrochemical device 15 in this embodiment, the water rolls on the electrode bases 16 and 17 in a spherical shape because of the water-repellent fluorine-based fibers. Therefore, even if water adheres to the apparatus using the electrochemical device 15, water does not enter the electrode bases 16 and 17, so that a space through which the gas passes is secured, and the reaction gas and the detection gas are detected. Is continuously supplied to the reaction section. Further, when water is generated by the reaction, since the fluorine-based fiber has a property of repelling water, the water generated by the reaction partially becomes spherical on the fluorine-based fiber, and the electrode substrate 16, Since it moves on 17 and a part of it is attracted to the metal fiber, a space is maintained in the entire electrode base materials 16 and 17, and the reaction gas can easily flow through the inside, so that it is necessary for the reaction. Gas continues to be supplied to the interface between the electrolyte membrane 14 as a reaction part and the electrode.
[0020]
Since electrons do not move in the organic fibers, it is not desirable to further increase the amount of the organic fibers. For example, even when the weight ratio is 10%, the specific gravity of the fluorine-based fiber is about 2.1 and the specific gravity of the metal fiber is 8.0, so that the volume ratio becomes 30%, and An insulating layer may be formed depending on the entanglement method. In that case, the movement of the electrons in the electrode substrate is hindered, and the characteristics deteriorate.
[0021]
Next, a modification of the electrochemical device 15 will be described. Here, hydrophilic aramid fibers were used as the organic fibers 22 and 32, and hair was mixed at a weight ratio of 3% or less.
[0022]
Next, the operation will be described. When water is sprayed on the electrochemical device 15 in this embodiment, the water is absorbed by the hydrophilic aramid fiber and moves through the electrode substrates 16 and 17 toward the electrolyte membrane 14. Therefore, when liquid water is supplied to the electrochemical device, water can be supplied to the reaction section while securing a space through which gas passes. In addition, when water is generated by the reaction, the water is drawn toward the organic fiber, so that water that hinders gas flow from the vicinity of the interface between the metal fiber and the electrolyte where electron transfer and electrochemical reaction occur is removed, and necessary for the reaction. The gas continues to be supplied to the interface between the electrolyte membrane 14 as the reaction part and the electrode.
[0023]
Also, here, the electrons do not move in the organic fibers, so that it is not desirable to increase the amount of the organic fibers further. For example, the specific gravity of aramid fiber is as small as 1.5, and the volume is substantially increased by being covered with moisture. In addition, as the hydrophilic organic fiber, natural fibers such as cotton and hemp can be used in addition to synthetic fibers such as polyester and acrylic, but decomposition occurs due to the functional group of the electrolyte membrane 14. Such is inappropriate.
[0024]
Embodiment 4 FIG.
Hereinafter, a fourth embodiment of the present invention will be described.
This electrochemical device is obtained by fluorinating the metal fibers 21 and 31 of the electrochemical device 15 according to the third embodiment. The shape and mechanical operation of the electrochemical device using the hydrophilic fiber according to the third embodiment are described. It is similar to the device 15. The fluorination of the metal fibers is the same as the fluorination of the cloth of the second embodiment.
[0025]
Next, the operation will be described. When water is sprayed on the electrochemical device 15 in this embodiment, the water rolls on the electrode bases 16 and 17 because of the water-repellent metal fibers. Even if is attached, water does not enter the electrode base materials 16 and 17 so that a space through which the gas passes is ensured, and the reaction gas and the gas to be detected are constantly supplied to the reaction section. On the other hand, when water is generated by the reaction, the water is attracted to the organic fiber, so that water that hinders gas flow from the vicinity of the interface between the metal fiber and the electrolyte where electron transfer and electrochemical reaction occur is removed, and the water necessary for the reaction is removed. Gas continues to be supplied to the interface between the electrolyte membrane 14 and the electrode base materials 16 and 17 which are reaction parts. Also, here, the electrons do not move in the organic fibers, so it is not desirable to increase the amount of the organic fibers more than necessary.
[0026]
Embodiment 5 FIG.
Hereinafter, a fifth embodiment of the present invention will be described. FIG. 3 is a schematic cross-sectional view of an electrochemical device 41 according to the fifth embodiment. In the figure, reference numerals 42 and 43 denote electrode substrates (gases) in which catalyst particles are supported on the electrode substrates 12 and 13 of the first embodiment. Diffusion electrode).
Platinum black (platinum fine particles) was used as the catalyst particles. There are various loading methods, and a solution in which 30% of platinum black is suspended in a weight ratio with respect to a lower alcohol solution containing 5% of a polymer electrolyte is applied to the electrode substrate by 1 cm. ² Per 4 mg and dried. Then, the electrode substrates 42 and 43 and the electrolyte membrane 14 were integrated by hot pressing described in the first embodiment.
[0027]
Next, the operation will be described. When hydrogen is supplied to one electrode substrate 42 of the electrochemical device 41 of this embodiment and a negative potential is applied to the other electrode substrate 43 with respect to the electrode substrate 42, In the chemical device 11, a current flows only when a potential between both electrodes is applied by 100 mV or more, and hydrogen is detected from the electrode substrate 13 side. In this embodiment, a current flows at 10 mV or more and the electrode substrate 43 It was confirmed that hydrogen was generated from the side. Thereby, it was confirmed that the platinum supported on the electrode base materials 42 and 43 became a catalyst and the electrochemical reaction was promoted. As for the catalyst, even when the same platinum is used as the catalyst, the so-called platinum-supported carbon catalyst in which platinum is supported on carbon fine particles has a low specific gravity. It is about 30%, and the amount of platinum when a catalyst supporting 20% is used is reduced to about 5% as compared with platinum black. Thus, the amount of platinum can be saved significantly, but the catalytic effect is somewhat reduced. The catalyst is not limited to platinum, but it can be used with other types of catalyst particles as long as it has a platinum metal element, an alloy containing them, or a catalyst that is generally commercially available and has a catalytic effect. In the case of adopting a method of supporting the substrate by coating, it is necessary to adjust the liquid.
[0028]
Embodiment 6 FIG.
This electrochemical device is obtained by plating platinum having a catalytic effect on each of the electrode substrates 12 and 13 of the first embodiment. To perform platinum plating, first, degreasing and cleaning are performed to remove impurities on the surfaces of the electrode substrates 12 and 13. In this state, since the electrode substrates 12 and 13 may repel the plating solution, the electrode substrates 12 and 13 are boiled in purified water for several minutes or immersed in 1N hydrochloric acid for several seconds. Then, it moves to a plating process. As the plating solution, a commercially available acidic type of phosphoric acid was used under the standard conditions, but there is no particular problem with other known solution compositions. However, the following phenomena have been encountered unlike the plate-like ones because of plating on the cloth. It is necessary to vibrate the fibers in the plating solution because the hydrogen bubbles generated during plating stay in the fibers and hinder the contact between the fiber surface and the plating solution and hinder the progress of plating. In addition, since the electrode bases 12 and 13 are flexible, there is a possibility that buoyancy acts on the portion with air bubbles and the electrode bases 12 and 13 are lifted, so that current can be applied while fixing four sides or both ends of the base. A jig was required (not shown). The plating amount was adjusted to an amount that would result in a plating thickness of 1 μm when the electrode substrate was regarded as a flat plate. Of course, it may be larger than this, but this amount was sufficient for the catalytic effect. 0.1A / cm depending on application ² In an apparatus operating at a low current density below, the plating amount may be extremely reduced. Further, even when other elements or alloys are used as the catalyst, a known plating technique according to the composition may be used.
[0029]
Next, the operation will be described. Since the catalytic effect is the same as that of the electrochemical device 41 of the fifth embodiment, the description is omitted. Even if the process of immersing the electrode substrate of this embodiment in boiling water for 5 hours and drying was repeated, the plating did not peel off. This indicates that even when used under conditions in which the flow of the reactants is strong, such as in a fuel cell or an electrolytic cell, the catalyst does not fall off and stable characteristics can be maintained.
[0030]
Embodiment 7 FIG.
Hereinafter, a seventh embodiment of the present invention will be described. FIG. 4 is a plan view of an electrochemical device 45 having a plurality of electronically independent electrode portions in a plane. In the figure, 12A, 12B, 12C and 12D are electronically independent electrodes on the same plane.
A 300 μm thick carbon paper was used as an electrode material. A 12 cm square electrolyte membrane 14 is placed on a 10 cm square electrode 13. Further, four independent electrodes 12A to 12D having a diameter of 4 cm and a Teflon (registered trademark) sheet 46 having a thickness of 250 μm and having holes formed therein for receiving the four independent electrodes 12A to 12D are arranged on the same plane. Then, hot pressing was performed under the same conditions as in the first embodiment. The surface pressure was based on the area of four independent electrodes. Further, a gas flow path through which a gas can flow through the electrode substrate 13, a flow path through which different gases can flow through the four electrodes, and a terminal for reading the voltage of each electrode were installed (not shown).
[0031]
Next, the operation will be described. Pure hydrogen was supplied to the electrode 13, and the fuel exhaust gas from the four cells of the fuel cell stack was supplied to each of the independent electrodes 12A to 12D. The voltage generated between each of the electrodes 12A, 12B, 12C, 12D and the electrode 13 is a voltage represented by the following equation (3) according to the hydrogen partial pressure of the fuel exhaust gas flowing through each flow path. Therefore, the concentration of four gases could be measured simultaneously in one electrochemical device.
[0032]
Here, a method of knowing the hydrogen concentration will be described. When pure hydrogen is passed through one of the poles and a test gas containing hydrogen is introduced into the other pole, a potential E corresponding to Nernst equation (3) is generated between the two poles. Thus, the hydrogen concentration in the gas to be inspected can be known.
[0033]
E = RT / 2F × 1n (P _H2 / P _R ・ ・ ・ ・ ・ (3)
[0034]
Where R is the gas constant, F is the Faraday constant, T is the absolute temperature, P _H2 Is the partial pressure of hydrogen gas in the test gas, P _R Indicates the pressure of pure hydrogen.
[0035]
In this embodiment, the four electrodes 12A to 12D are arranged on the same plane. However, as long as the electrodes are a plurality of electronically independent electrodes, the number of electrodes is larger or smaller. There may be.
Further, in the present embodiment, the counter electrode 3 is constituted by one sheet. However, the counter electrode 3 may be divided into four parts corresponding to the electrodes 12A, 12B, 12C, and 12D to constitute four electronically independent batteries. It is possible. In that case, by connecting four batteries in series, it is possible to generate an average of four times the voltage.
[0036]
Embodiment 8 FIG.
Hereinafter, an eighth embodiment of the present invention will be described. FIG. 5 is a view showing the concept of an electrochemical device 51 according to the eighth embodiment. FIG. 5A is a plan view thereof, and FIG. 5B is a sectional view thereof. In the figure, 12R and 12W are electronically independent electrodes in the same plane, and 52 is a partition (sealing portion) that shields the electrode 12R from the outside air. As the electrodes 12R and 12W, the electrodes according to the sixth embodiment in which the electrode base material was plated with platinum were used. Assembling is performed by placing a 12 cm square electrolyte membrane 14 on a 10 cm square electrode 13, and further placing an electrode 12 R having a diameter of 1 cm and an electrode 12 W having a hole of 1.5 cm in diameter on the same plane. Line up. Then, hot pressing was performed under the same conditions as in the first embodiment. The surface pressure was based on the area of the counter electrode 13. Then, in order to prevent outside air from flowing into the electrode 12R, a hemispherical cap (partition wall 52) made of silicon rubber having a hole for a voltage terminal and a thickness of 0.2 mm and a radius of 1.2 cm was covered. Then, the electrodes were sandwiched between SUS304 punching metals each having a thickness of 2 mm and having a thickness of 1 mm, and terminals for reading the voltages of both the punching metals and the electrodes 12R were provided (not shown). At this time, one punching metal is electronically connected to the electrode 12W, the other punching metal is electronically connected to the electrode 13, and the electrode 12R is in an electrically insulated state except for the voltage terminal. Has become.
[0037]
Next, the operation will be described. The electrochemical device 51 is placed in the air, and a potential of 4 V is applied between the electrode 12W and the counter electrode 13 through a punching metal. Moisture in the air that is in contact with the electrode 13 becomes hydrogen ions and moves through the electrolyte membrane 14 toward the electrodes 12W and 12R in accordance with Equation (4) described later. At the electrode 12W, the hydrogen ions are reduced to hydrogen according to the formula (5) described later, and immediately react with oxygen in the air to become water. On the other hand, in the electrode 12R, the hydrogen ions obtain electrons and become hydrogen as shown in the formula (7) described later, but are filled with hydrogen gas because they are sealed by the rubber cap 52, and only excess hydrogen is generated. , Flows out between the rubber cap 52 and the membrane 14.
[0038]
Here, the movement of hydrogen ions will be described. When a DC voltage is applied to both electrodes in moist air, the water in the air loses electrons on the anode side to become hydrogen ions due to an electrochemical reaction, and moves to the cathode side through the electrolyte membrane.
2H ₂ O → 4H ⁺ + O ₂ + 4e ⁻ ・ ・ ・ ・ ・ (4)
The hydrogen ions obtain electrons on the cathode and are reduced to hydrogen, but react with oxygen in the air to become water.
4H ⁺ + O ₂ + 4e ⁻ → 2H ₂ O ... (5)
Eventually, the water on the anode side moves to the cathode side, and lowers the humidity of the space on the anode side.
Also, for example, when a DC voltage is applied to both electrodes in water, the water loses electrons at the anode and becomes hydrogen ions and oxygen gas at the anode due to an electrochemical reaction, oxygen gas is generated as gas, and hydrogen ions pass through the electrolyte membrane on the cathode side. Move to. On the other hand, at the cathode, hydrogen ions obtain electrons and are generated as hydrogen gas.
2H ₂ O → 4H ⁺ + O ₂ + 4e ⁻ ・ ・ ・ ・ ・ (6)
4H ⁺ + 4e ⁻ → 2H ₂ ・ ・ ・ ・ ・ (7)
[0039]
As described above, the electrode 12R becomes a hydrogen reference electrode, and by measuring the voltage of the electrode 12R and the counter electrode 13 and the voltage of the electrode 12R and the electrode 12W, in this electrochemical reaction, the polarization of each electrode is separated and measured. Can be. Therefore, by adjusting the voltage applied between 12W and 13 based on this voltage, it is possible to avoid the danger of applying an abnormal voltage to the electrode that would cause corrosion of the electrode, and it is possible to operate with the maximum required voltage. Therefore, the device can be made compact.
[0040]
Embodiment 9 FIG.
Hereinafter, a ninth embodiment will be described with reference to the drawings. FIG. 6 is a conceptual sectional view of an electrochemical device 53 according to the ninth embodiment. In the figure, reference numerals 54 and 55 denote electrode substrates having through holes 56, and reference numeral 14 denotes a polymer electrolyte membrane. As the electrode substrate, a single fiber of SUS316L described in Embodiment 1 having a diameter of 12 μm and a length of 50 to 100 mm was sintered after being passed through a spreader, and a basis weight of 400 g / cm. ² Cloth was used. When Nafion 117 manufactured by DuPont is used as a commercially available perfluorosulfonic acid film for the polymer film 14, the electrode substrates 54 and 55 and the polymer film 14 are weighed at 190 ° C. at 50 kg / cm. ² When hot pressing was performed at the surface pressure of 1 to perform integration, the fibers of the electrode base material penetrated the polymer membrane 14 by 50 μm, and the electrolyte membrane 14 penetrated so as to fill the through holes 56.
[0041]
Next, the operation will be described. Even when manufacturing an integrated electrochemical device 53 having a size of 10 cm square, even when handling only one end by hand due to the steel nature of the electrode base material, the integrated material separates and causes unreproducible distortion. I never did. Further, the operation of immersing this integrated product in water and drying it in the air at 100 ° C. was repeated 10 times, but the electrode substrates 54 and 55 and the polymer film 14 were not separated at all, and the shape of the integrated product changed. Did not. When this test was carried out using a conventional electrode substrate, cracks started in the holes formed in the electrode substrate, and the substrate was cracked and peeled off. Further, when the electric resistance between the electrode substrates 54 and 55 of the present embodiment was examined, a low resistance was maintained during the immersion and drying.
Since the polymer electrolyte membrane 14 itself expands and contracts depending on the water content, the test showed that the adhesion between the electrode base polymer membrane 14 and the bases 54 and 55 was very strong, and that the strength of the metal fibers was high. Thus, it is considered that the movement of the membrane could be restricted.
[0042]
Further, since the electric conductivity of SUS316L itself is about 10 times that of carbon, electrons in the base material can be smoothly moved, and the voltage loss can be kept low. In addition, since the electrolyte membrane has penetrated into the through-holes, the water that has entered in a liquid state directly contacts the electrolyte membrane, thereby facilitating the supply of water to the membrane. If the diameter of the metal fiber is smaller than this time, the surface area per unit volume increases and the reaction area increases, but the gas permeation resistance increases. It is desirable to use a cloth. Conversely, those having a large fiber diameter can be used having a large basis weight. By tightening with a frame or the like, when the steel properties of the electrode base material itself are not so required, it is also possible to use a felt that does not perform sintering.
[0043]
Embodiment 10 FIG.
Embodiment 10 will be described below. FIG. 7 is a schematic sectional view of an electrochemical device 58 according to the tenth embodiment. 59 is a layer made of hydrophilic fibers. Here, a nonwoven fabric having a fiber diameter of 1 μm and a thickness of 2 mm was used.
[0044]
Next, the operation will be described. When water is sprayed on the electrochemical device 58, the water spreads on the hydrophilic layer 59 and is distributed almost uniformly in the plane, and then reaches the electrolyte membrane 14 via the electrode 12. On the other hand, when water is generated by the reaction at the interface between the electrolyte membrane 14 and the electrode 12, excess water is absorbed by the hydrophilic layer 59, spreads over the entire surface, and is removed. A space is maintained in the entire base material, and the reaction gas can easily flow through the space, so that the gas required for the reaction is continuously supplied to the interface between the electrolyte membrane 14 as the reaction part and the electrode interface. However, since electrons do not move in the organic fiber, the exchange of electrons between the electrode base material 12 and the outside may be performed by extracting a terminal from between the hydrophilic layer 59 and the electrolyte membrane 14 or forming a hole in a part of the hydrophilic layer 59. It is necessary to open only the terminals so that it is not suitable for operation in which a large current flows. Other hydrophilic fibers include synthetic fibers such as polyamide and polyethylene, as well as natural fibers such as cotton and hemp. However, synthetic fibers that can freely control the pore diameter in the layer are preferable. In the above-described embodiment, a device having a thickness of 2 mm is used. However, when the device is applied to the water discharging side of the dehumidifying element, there is no problem even if the thickness is further increased, and the device is operated at room temperature without directly touching the electrolyte membrane 14. Therefore, there is no need to consider much of the limitation of material selection other than hydrophilicity. It is also possible to carry a known water-supplying polymer on the outside of the hydrophilic layer.
[0045]
Embodiment 11 FIG.
Embodiment 11 will be described below. FIG. 8 shows an electrochemical device 61 of the eleventh embodiment in which a bent electrode and an electrolyte membrane are integrated, wherein a gas diffusion electrode 62 and 63 are bent, and a bent electrolyte membrane (solid polymer Electrolyte). Further, 65 is a gas flow path formed by the electrode 62, and 66 is a gas flow path formed by the electrode 63. Numerals 68 and 69 are conductive separator plates forming the other end of the gas flow path. Reference numeral 70 denotes an insulating spacer film using a Teflon (registered trademark) sheet having a thickness of 250 μm. No special technique is required for bending the gas diffusion electrode, and the gas diffusion electrode can be implemented by a known sheet metal press. When the electrodes 62 and 63 are integrated with the electrolyte membrane 64, a method disclosed in, for example, JP-A-3-84866, JP-A-3-208261, and JP-A-3-208262 may be used. If this is the case, it is easy to make the film conform to the shape of the bent electrode substrate. Here, a gas flow path having a width of 2 mm was formed from a sintered electrode base material of SUS316L fiber.
[0046]
Next, the operation will be described. In the electrochemical device 61, a hydrogen gas purification reaction, which is one of the electrochemical reactions, is performed. When a hydrogen gas containing carbon dioxide as an impurity is introduced into the gas passage 65 and a voltage of 0.5 V is applied to the separator plate 68 with respect to the separator plate 69, a reaction of the following formula (8) occurs on the electrode 62, Only the hydrogen gas becomes protons and moves in the electrolyte 64 toward the electrode 63, and returns to the hydrogen gas by the reaction of the formula (9) described later and is introduced into the flow path.
[0047]
Here, when a hydrogen gas containing impurities is caused to flow on the anode side and a voltage is applied, only the hydrogen gas reacts to become hydrogen ions, and moves to the cathode side in the electrolyte membrane.
H ₂ → 2H ⁺ + 2e ⁻ ・ ・ ・ ・ ・ (8)
2H ⁺ + 2e ⁻ → H ₂ ・ ・ ・ ・ ・ (9)
On the cathode side, hydrogen ions obtain electrons and are reduced to hydrogen gas. Since only hydrogen ions can move in the electrolyte membrane, pure hydrogen can be obtained on the cathode side.
[0048]
Therefore, the electrons flow from the electrode 62 through the separator plate 68 to the separator plate 69 and the electrode 63 via the external circuit. Although the thickness of the electrode substrate is about 0.3 mm, since the metal fibers have high conductivity, there is almost no voltage loss even when electrons move from the top 65T of the longest flow path to the separator plate 68. The reaction proceeds. Also, at this time, the interface area between the electrolyte and the electrode per simple flat area is doubled and wide, so that a large reaction area is secured and a large amount of gas can be purified. Further, since the electrochemical device itself constitutes the flow path while keeping the thickness of the electrode thin, the thickness of the unit battery becomes very thin, and the laminated body in which the batteries are laminated can be made very compact. Regarding the contact resistance between the separator and the electrode, the contact surface pressure can be maintained by utilizing the elasticity of the metal fiber, so that the voltage loss can be kept low.
[0049]
Embodiment 12 FIG.
Embodiment 12 will be described below. FIG. 9 shows an electrochemical device 71 sandwiched between elastic current collectors according to the twelfth embodiment. Reference numeral 72 denotes an elastic current collector, 73 denotes a counter electrode current collector, and 70 denotes an insulating spacer. As the material of the elastic current collector 72, besides austenitic stainless steel and martensitic stainless steel, known metals and alloys having spring properties can be used, and a plastic film coated with a conductive layer can be used. However, it is necessary to select in consideration of corrosion resistance depending on operating conditions. Here, for use in a dehumidifier operated at room temperature and in air, a SUS316L plate having a thickness of 0.05 mm and provided with holes for gas permeation was used. The holes can be made by known methods such as punching, etching or machining. The size of the elastic current collector 72 is 10 cm square, and is processed into an arc having a radius of 10 cm. As the gas diffusion electrode, the electrode of Embodiment 6 in which SUS fiber felt is plated with platinum is used. In the assembly, the electrode 12, the electrolyte membrane 14, and the electrode 13 are superimposed on the current collector 73, and the elastic current collector 72 is placed on the current collector 73 so that the center of the arc faces outward. The frame 74 was made of hard polyethylene having a thickness of 3 mm and was fixed to the current collector 73 using screws or the like. A terminal for flowing a current is attached to the elastic current collector 72 (not shown).
[0050]
Next, the operation will be described. When a voltage of 4 V is applied to the current collector 72 with respect to the current collector 73 in the atmosphere, the above-described reaction of the formula (4) occurs on the electrode 12, and moisture in the air on the current collector 73 side is decomposed. As a result, protons move through the electrolyte 14 toward the electrode 13 and combine with oxygen in the air by the reaction of the formula (5) to come out as water. At this time, electrons flow from the electrode 12 through the current collector 73 to the current collector 72 and the electrode 13 via the external circuit. The contact resistance between the current collector 72 and the electrode 13 can maintain the contact surface pressure by utilizing the elasticity of the current collector 72, so that the voltage loss can be kept low. In addition, since an electrode and an electrolyte membrane that are not integrated can be used in this method, the integration step can be omitted. In this embodiment, the electrode substrate itself having a catalytic function is used. However, the catalysis is not particularly required to be integrated with the electrode, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-46764. Such a catalyst sheet may be inserted between the electrode substrate and the electrolyte membrane.
Further, the total thickness is as thin as 0.7 mm, so that it can be made compact even when attached to various devices.
[0051]
Embodiment 13 FIG.
Embodiment 13 will be described below. FIG. 10 is a conceptual cross-sectional view of a fuel cell 81 using an electrochemical device 53 (FIG. 6) according to Embodiment 13 of the present invention. There are certain anodes, and reference numerals 68 and 69 denote separator plates having carbon gas flow paths. The effective area of each electrode 54, 55 of the electrochemical device 81 is 100 cm ² Was used. The electrolyte membrane 14 used was Nafion 115 manufactured by DuPont.
[0052]
Next, the operation will be described. The fuel cell 81 was heated to 80 ° C. by an external heater (not shown), and hydrogen gas humidified at 95 ° C. was introduced into the anode channel 66, and air humidified at 50 ° C. was introduced into the cathode channel 65. When the space between the separator plates 69 and 68 is connected to an external circuit, hydrogen is released on the anode 55 by the reaction of the formula (10) and moves with the water toward the cathode 54 along with the water.
2H ₂ → 4H ⁺ + 4e ⁻ ・ ・ ・ ・ ・ (10)
At the cathode 54, hydrogen ions and oxygen are combined to obtain electrons to generate water.
4H ⁺ + O ₂ + 4e ⁻ → 2H ₂ O ... (11)
At this time, since the temperature of the cell is lower than the dew point (95 ° C.) of the anode gas, excess water is condensed as droplets in the flow path 66. The droplets touch the electrolyte membrane 14 filling the through holes 56 in the electrodes while being carried by the dynamic pressure of the gas in the flow path 66, and are partially absorbed and partially absorbed by the electrolyte membrane in the through holes 56. The electrolyte flows along the inside of the electrolyte membrane 14. On the other hand, in the cathode 54, although there is excess water, the electrolyte membrane 14 filling the through-hole 56 has higher hydrophilicity than the electrode 54, so that water moves along the through-hole 56 into the flow path 65 and flows therethrough. Evaporates on contact with air. Thereby, the water required for the electrochemical reaction can be supplied, and the water in the cathode electrode 54 can be quickly discharged, so that the supply of oxygen required for the reaction is maintained, and high characteristics can be obtained even when the current density is increased. Can be maintained.
[0053]
Embodiment 14 FIG.
Embodiment 14 will be described below. FIG. 11 shows a dehumidifier 91 using an electrochemical device 71 according to Embodiment 14 of the present invention, wherein 72 is an elastic current collector, 92 is a DC power supply, 93 is a housing to be dehumidified, and 94 is a side wall of the housing 93. The hole may be formed by joining a well-known metal plate made by, for example, punching, etching, or machining. Here, SUS304 punched metal having a thickness of 0.5 mm was used. Although the window 94 serves as a current collector, the window 94 is unpainted so as not to form an insulating layer. However, the window 94 is insulated and fixed to the housing 93. A frame 74 for fixing the dehumidifying element is provided outside the housing 93.
The frame 74 is attached to the housing by welding a steel plate of the same quality as the housing. The outside was painted the same as the casing, but the inside was unpainted to conduct with the current collector 72. The current collector 72 has a size of 10 cm square and is bent into an arc having a radius of 10 cm. The electrochemical device 71 is a gas diffusion electrode, an electrode of the sixth embodiment in which SUS fiber felt is plated with platinum, and a Nafion 117 film at 150 ° C. and a surface pressure of 50 kg / cm. ² The one integrated with was used. The reason for lowering the heating temperature is to prevent the backflow of water by keeping the thickness of the electrolyte membrane 14 large by reducing the penetration of the electrode into the membrane. The integration is somewhat inferior, but there is no problem because it is pressed by the current collector 72. The electrode 12 has a thickness of 400 μm and a thickness of 400 g / cm. ² The electrode 13 has a thickness of 200 μm and a thickness of 200 g / cm. ² Is used. In the assembly, the electrochemical device was inserted along the frame 74 such that the electrodes 13 faced toward the housing, and the current collector 72 was inserted from above such that the center of the arc was directed toward the outside of the housing. The + terminal of the DC power supply is connected to the window 94, and the − terminal is connected to the housing 93 with the ground.
[0054]
Next, the operation will be described. When the DC power supply is started, a voltage of 4 V is applied to the window 94 with respect to the housing 93. The window 94 is electrically connected to the electrode 13, and the housing 93 is electrically connected to the electrode 12 via the frame 74 current collector 72, so that a voltage of 4 V is applied to the electrode 13 with respect to the electrode 12. Then, the reaction of the formula (3) occurs on the electrode 13, the water in the air in the housing 93 is decomposed, and the proton moves through the electrolyte 14 toward the electrode 12, and the reaction of the formula (4) Therefore, it combines with oxygen in the outside air and comes out as water. At this time, electrons flow from the electrode 13 through the window 94 through the DC power supply 92 to the housing 93, the frame 74, the current collector 72, and the electrode 12. The contact resistance between the current collector 72 and the electrode 12 can maintain the contact surface pressure by utilizing the elasticity of the current collector 72, so that the voltage loss can be kept low. Further, in this method, the electrochemical device is simply fixed by the elasticity of the current collector plate, so that it can be easily replaced by simply removing the electrochemical device 71 at the time of repair. When the volume of the housing 93 was about 10 liters, the relative humidity in the housing 93 could be suppressed to about 40 to 50% lower than that of the atmosphere. When the electrochemical device according to the eleventh embodiment is used, a large amount of gas can be dehumidified. Therefore, if it is placed on the windward side of a cooling fin of an air conditioner, dew condensation in the fin can be prevented, and oxygen enrichment can be prevented. Becomes possible.
[0055]
Embodiment 15 FIG.
Hereinafter, a fifteenth embodiment will be described. FIG. 12 is a conceptual cross-sectional view of a gas concentration sensor 101 using an electrochemical device 45 of Embodiment 7 having a plurality of electronically independent electrode portions in a plane. In the figure, 12A, 12B, 12C and 12D are electronically independent electrodes on the same plane. A 300 μm thick carbon paper was used as an electrode material. A 12 cm square electrolyte membrane 14 is placed on the 10 cm square electrode 13 so as to protrude by 1 cm at a time. Further, 16 independent electrodes of 2 cm square are arranged thereon at intervals of 6 mm between the electrodes as shown in FIG. Then, hot pressing was performed under the same conditions as in the first embodiment. The surface pressure was 64 cm in area of 16 independent electrodes. ² Based. Further, a gas flow path 102 through which gas can flow through the counter electrode 13 and flow paths 103A through 103P (up to 103A through 103D in the figure) through which different gases can flow through 16 electrodes were provided. A voltage terminal 104 was connected to the electrode 13 via a current collector (not shown). The voltage terminals 105A to 105P were also connected to the electrodes 12A to 12P. Note that polycarbonate was used for the end plates 106 and 107. Although it is possible to use a conductive metal material for the end plate 106, it is necessary to electrically insulate the electrodes 12 </ b> A to 12 </ b> P at the end plate 107, so if a conductive material such as metal or carbon is used, At this time, it is necessary to prevent the conductive portion from touching the electrode.
[0056]
Next, the operation will be described. Pure hydrogen was passed through the flow channel 102, and fuel exhaust gas from 16 cells of the fuel cell stack was passed through each of the independent electrodes. The voltage generated between each of the electrodes 12A to 12P and the electrode 13 becomes a voltage represented by Expression (3) according to the hydrogen partial pressure of the fuel exhaust gas flowing through each of the flow paths. By monitoring the voltage between 104-105A and 104-105P, the hydrogen concentration of the exhaust gas of the 16 cells of the fuel cell stack could be measured simultaneously. In this test, a methane reforming simulation gas (80% hydrogen, residual carbon dioxide) was flowed as fuel into the fuel cell. Each cell voltage in the stack varied by measurement, but it was not known what the variation was based on. However, when this concentration sensor was installed, it was found that the inter-terminal voltage of the electrode through which the exhaust gas of the cell having a low cell voltage passed was higher than that of the other cells, and the hydrogen concentration was extremely low. In the fuel cell stack, since the current flowing through each cell is the same, the amount of consumed hydrogen gas is also the same.
Nevertheless, the low hydrogen concentration indicates that the fuel flowing into the cell is small, and it is clear that there is a problem in the distribution of gas in the stack. This can be performed by monitoring the voltage, and the characteristics of the fuel cell stack have been greatly improved.
[0057]
In the present embodiment, the gas concentration is measured by measuring the voltage with the electrode 13 through which pure hydrogen has flowed. However, if only the variation in the concentration is measured as in this case, the reference electrode 13 may be used. It is also possible to know the concentration distribution by ignoring the potential and monitoring only the variations in the potentials of 12A to 12P. For example, when the number of divided electrodes is limited to two cells, the exhaust gas from the cells at both ends where the distribution of gas is most likely to be biased is introduced into the channels 103A and 103B, and the exhaust gas from the central cell is introduced into the channel 102. If the voltage between -103B exceeds a certain value, it is also possible to adopt an operation method of increasing the total gas flow rate and keeping the stack operation normal.
[0058]
Embodiment 16 FIG.
Embodiment 16 will be described below. FIG. 14 shows an electrolytic cell 111 using the electrochemical device 51 of the sixteenth embodiment, wherein 112 is an electrolytic cell container, 13 is an anode, 12 W is a cathode, 12 R is an independent cathode, 113 anode current collector, and 114 is a cathode current collector. An electric body, 52 is a silicone rubber cap, 115 is a water supply port, 116 is an oxygen discharge port, 117 is a hydrogen discharge port, and 118 is a current (voltage) terminal to the electrode 12R. The electrode has a thickness of 0.1 mm and a weight of 100 g / cm. ² The electrodes 12W and 12R were plated with platinum, and the electrodes 13 were plated with iridium. A Nafion membrane was used as the electrolyte membrane 14 as a perfluorosulfonic acid membrane.
[0059]
Next, the operation will be described. When a DC voltage is applied between the electrodes 12W-13, water is decomposed by the reaction of the formula (6) on the anode 13 to generate oxygen, while hydrogen gas is generated on the cathode 12W according to the formula (7). Further, when the terminal 118 was short-circuited to the cathode, hydrogen was also generated from 12R, the inside of the rubber cap 52 was filled with hydrogen, and a part thereof overflowed from the gap between the rubber cap 52 and the film 14. Current density of 500 mA / cm ² When the current was passed about, the voltage between the electrodes was about 2 V. However, if the operation was continued at this current density for a while, the voltage increased and the current stopped flowing. When the voltage between the terminal and the anode or between the terminal and the cathode when the terminal 118 was disconnected from the cathode was measured, the voltage between the terminal 118 and the anode 13 changed when the voltage increased. The voltage between 118 changed little. Therefore, it was presumed that the deterioration of the characteristics of the electrolytic cell 111 was caused by a problem on the anode electrode side. Therefore, when the test was performed with attention paid to the anode, water was supplied due to oxygen bubbles generated on the anode. I knew she was dripping.
Therefore, when the electrode substrate of the anode was changed to one having a half thickness, no increase in voltage occurred. As described above, when the voltage of the electrode 13 is measured by disconnecting the circuit of the terminal 118 at regular intervals during the operation, when there is a problem in the electrolytic cell 111 or when the characteristics start to deteriorate, the cause is determined. Or repair a problematic part just before it breaks down.
[0060]
Embodiment 17 FIG.
Hereinafter, a seventeenth embodiment will be described. FIG. 15 shows a gas purification apparatus 121 using the electrochemical device 61 of the seventeenth embodiment. The lower part of the electrochemical device (represented by a single curve) is the anode 62 and the upper part is the cathode 63. The electrode substrate has a basis weight of 300 g / cm. ² A gas flow path having a width of 2 mm and a height of 2 mm was formed from a sintered electrode substrate of SUS316L fiber having a thickness of 250 μm. 65 is a gas flow path formed by the electrode 62, and 66 is a gas flow path formed by the electrode 63. Reference numerals 68 and 69 denote conductive end plates forming the other ends of the gas passages, and reference numeral 122 denotes a conductive separator plate, which electrically connects four purifying devices in series. The four devices were labeled A to D, respectively. Each of the separator plates 122 is made of a SUS304 plate, and a Teflon (registered trademark) resin is used for a gas seal with an electrolyte membrane and a manifold for a gas flow path with a bent electrode (not shown). Further, finally, the laminate is 0.2 kg / cm ² The contact pressure between the end plates 68-69 is held down by the surface pressure.
[0061]
Next, the operation will be described. When a hydrogen gas containing carbon dioxide as an impurity is introduced into the gas channels 65A to 65D and a voltage of 2 V is applied to the end plate 68 with respect to the end plate 69, the reaction of the formula (8) occurs on the electrodes 62A to 62D, Only the hydrogen gas becomes protons and moves in the electrolytes 14A to 14D toward the electrodes 63A to 63D, and returns to the hydrogen gas by the reaction of the formula (9) and is introduced into the flow paths 66A to 66D. Further, at this time, the interface area between the electrolyte and the electrode per simple flat area was doubled, so that almost twice the current as in the case of using the flat electrode could be passed. This means that a gas purification device having the same bottom area can process twice as much gas. Furthermore, since the flow path was formed by the electrochemical device 61 itself while keeping the thickness of the electrode thin, the thickness per sheet was reduced by 30% as compared with the case where the flow path was dug in the separator plate. Was about 2/3. For this reason, the size of a plate-type gas purification device of the same size is reduced to about 1/3, and a remarkable miniaturization is possible. Further, since it is not necessary to dig a groove in the separator, a commercially available thin plate can be used as in the present embodiment, and the cost can be significantly reduced.
[0062]
【The invention's effect】
As described above, according to the present invention, since the gas diffusion electrode is configured to be bent and integrated with the solid polymer electrolyte, the electrode area per unit area can be increased, and the electrochemical reaction can be performed. Since the device can be smoothly advanced and a small space can be effectively used, there is an effect that the device can be significantly reduced in size.
[0063]
According to this invention, since the gas diffusion electrode is configured as either a mixed woven fabric or a mixed nonwoven fabric of metal fibers and organic fibers having different hydrophilic properties, the deformation of the solid polymer electrolyte is mechanically prevented. The gas required for the reaction can easily flow into the reaction portion, and excess water that inhibits gas diffusion can be easily discharged from the reaction portion, and the electrode area per unit area can be increased. The effect is that the electrochemical reaction proceeds smoothly.
[0064]
According to the present invention, since the gas diffusion electrode is made of either a woven or non-woven metal fiber and the metal fiber is fluorinated, the gas diffusion electrode mechanically deforms the solid polymer electrolyte. In addition to this, the gas required for the reaction can easily flow into the reaction portion, and the electrode area per unit area can be increased, so that the electrochemical reaction can smoothly proceed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an electrochemical device according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view illustrating a configuration of an electrochemical device according to Embodiment 3 of the present invention.
FIG. 3 is a sectional view showing a configuration of an electrochemical device according to Embodiment 5 of the present invention.
FIG. 4 is a plan view showing a configuration of an electrochemical device according to Embodiment 7 of the present invention.
FIG. 5 is a plan view and a cross-sectional view illustrating a configuration of an electrochemical device according to Embodiment 8 of the present invention.
FIG. 6 is a sectional view showing a configuration of an electrochemical device according to Embodiment 9 of the present invention.
FIG. 7 is a sectional view showing a configuration of an electrochemical device according to Embodiment 10 of the present invention.
FIG. 8 is a sectional view showing a configuration of an electrochemical device according to Embodiment 11 of the present invention.
FIG. 9 is a sectional view showing a configuration of an electrochemical device according to Embodiment 12 of the present invention.
FIG. 10 is a sectional view showing a fuel cell using an electrochemical device according to Embodiment 13 of the present invention.
FIG. 11 is a cross-sectional view illustrating a dehumidifier using an electrochemical device according to Embodiment 14 of the present invention.
FIG. 12 is a sectional view showing a gas concentration sensor using an electrochemical device according to Embodiment 15 of the present invention.
FIG. 13 is a plan view showing a configuration of an electrode of a gas concentration sensor using an electrochemical device according to Embodiment 15 of the present invention.
FIG. 14 is a cross-sectional view showing an electrolytic cell using an electrochemical device according to Embodiment 16 of the present invention.
FIG. 15 is a cross-sectional view showing a gas purifying apparatus using an electrochemical device according to Embodiment 17 of the present invention.
FIG. 16 is a sectional view showing a conventional electrochemical device.
[Explanation of symbols]
Reference Signs List 11 electrochemical device, 12, 13 metal fiber electrode base material (gas diffusion electrode), 14 solid polymer electrolyte membrane, 15 electrochemical device, 16, 17 electrode base material (gas diffusion electrode), 21, 31 metal fiber, 22 , 32 Organic fiber, 41 Electrochemical device, 42, 43 Electrode substrate (gas diffusion electrode), 45 Electrochemical device 51 Electrochemical device, 52 Partition wall (sealing part), 53 Electrochemical device, 54, 55 Electrode substrate , 56 through hole, 58 electrochemical device, 59 layer made of hydrophilic fiber, 61 electrochemical device, 62, 63 gas diffusion electrode, 64 electrolyte membrane (solid polymer electrolyte), 71 electrochemical device, 72 elastic collection Current collector, 73 current collector.

Claims (3)

An electrochemical device in which gas diffusion electrodes are provided on both sides of a solid polymer electrolyte, wherein the gas diffusion electrodes are bent and integrated with the solid polymer electrolyte. 2. The electrochemical device according to claim 1, wherein the gas diffusion electrode is one of a mixed woven fabric of a metal fiber and an organic fiber or a mixed nonwoven fabric, and the metal fibers and the organic fibers have different hydrophilicity. 3. The electrochemical device according to claim 1, wherein the gas diffusion electrode is made of one of a woven fabric and a nonwoven fabric of metal fibers, and the metal fibers are fluorinated.

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