CN117321249A - Anode gas diffusion layer for water electrolysis unit, and water electrolysis apparatus - Google Patents
Anode gas diffusion layer for water electrolysis unit, and water electrolysis apparatus Download PDFInfo
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- CN117321249A CN117321249A CN202280033798.2A CN202280033798A CN117321249A CN 117321249 A CN117321249 A CN 117321249A CN 202280033798 A CN202280033798 A CN 202280033798A CN 117321249 A CN117321249 A CN 117321249A
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- 239000010408 film Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
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Abstract
The present invention relates to an anode gas diffusion layer (1) for a water electrolysis unit, which comprises metal fibers, wherein the surface of the metal fibers is formed of nickel.
Description
Technical Field
The present disclosure relates to an anode gas diffusion layer for a water electrolysis unit, and a water electrolysis apparatus.
Background
In recent years, development of an anode gas diffusion layer used in a water electrolysis apparatus has been expected.
Patent document 1 describes an electrode for electrolysis using a metal porous body having a metal skeleton and a metal oxide thin film formed on at least part of the surface of the metal skeleton. The electrolysis electrode is used, for example, as an electrolysis electrode of a hydrogen generator. The metal skeleton is Ni or Ni alloy, and the metal oxide is a metal oxide other than NiO. According to the method for producing a metal porous body described in patent document 1, a Ni plating film is formed on the surface of a porous body base material, and then Al is formed on the surface of the plating film 2 O 3 A thin film of an oxide of such a metal. Therefore, it can be understood that Al is formed on the surface of the metal porous body described in patent document 1 2 O 3 A thin film of an oxide of such a metal.
Patent document 2 describes a membrane electrode assembly comprising: a pair of electrodes made of a conductive material and having a porous power-feeding layer, and an electrolyte membrane disposed between the pair of electrodes. The membrane electrode assembly is used, for example, in an electrochemical cell of a hydrogen production apparatus.
Non-patent document 1 describes a membrane electrode assembly in which a material such as Ti or Ni foam covered with Pt is used for an anode gas diffusion layer. Non-patent document 1 does not describe the durability of the anode gas diffusion layer.
Prior art literature
Patent document 1: international publication No. 2020/217868
Patent document 2: japanese patent laid-open publication No. 2019-49043
Non-patent document 1: renewable and Sustainable Energy Reviews (review of renewable and sustainable energy), volume 81 (2018) pages 1690-1704
Disclosure of Invention
An object of the present disclosure is to provide an anode gas diffusion layer for a water electrolysis unit, which is capable of suppressing an overvoltage increase of the water electrolysis unit and has excellent durability.
The present disclosure provides an anode gas diffusion layer for a water electrolysis unit,
is provided with a metal fiber which is made of a metal material,
the metal fiber has a surface formed of nickel.
According to the present disclosure, it is possible to provide an anode gas diffusion layer for a water electrolysis unit, which is capable of suppressing an overvoltage increase of the water electrolysis unit and has excellent durability.
Drawings
Fig. 1 is a schematic diagram showing an example of a water electrolysis unit according to the present embodiment.
Fig. 2 is a diagram schematically showing an example of the metal fiber according to the present embodiment.
Fig. 3 is a cross-sectional view schematically showing an example of the water electrolysis apparatus according to the present embodiment.
Fig. 4 is a cross-sectional view schematically showing another example of the water electrolysis unit according to the present embodiment.
Fig. 5 is a cross-sectional view schematically showing another example of the water electrolysis apparatus according to the present embodiment.
Fig. 6 is a view showing the result of observing the nickel fiber sintered body with a scanning electron microscope.
Fig. 7 is a graph showing the result of the change in voltage with time caused by the gas generation of the water electrolysis unit.
Fig. 8 is a graph showing the measurement result of the change in contact resistivity of the anode gas diffusion layer with respect to pressure.
Detailed Description
(insight underlying the present disclosure)
As a countermeasure for global warming, the use of renewable energy sources such as sunlight and wind power has been attracting attention. However, in power generation using renewable energy sources, there is a problem in that output fluctuation is large. Further, in the power generation using renewable energy, there is a problem that surplus power is wasted. Therefore, the utilization efficiency of renewable energy is not necessarily sufficient. Therefore, a method of effectively utilizing surplus electric power by producing and storing hydrogen from surplus electric power is being studied.
As a method for producing hydrogen from surplus electric power, electrolysis of water is generally used. Electrolysis of water is also known as water electrolysis. In order to produce hydrogen stably at low cost, development of a highly efficient and long-life water electrolysis apparatus is required. As a main component of the water electrolysis apparatus, a Membrane Electrode Assembly (MEA) composed of a gas diffusion layer, an electrode catalyst layer, and an electrolyte membrane is exemplified.
In order to provide a highly efficient and durable water electrolysis device, it is particularly important to improve the performance and durability of the gas diffusion layers for the anode and cathode. The gas diffusion layer can be formed by bonding carbon fibers having a wire diameter of about 8 μm with an adhesive, for example. However, carbon fibers are easily oxidized and decomposed at a high potential. Therefore, the function as a gas diffusion layer may be lowered due to the use of the water electrolysis apparatus employing carbon fibers. Thus, the water electrolysis performance may be lowered. Therefore, it is important to develop a gas diffusion layer that is less susceptible to oxidative degradation.
Patent document 1 describes a hydrogen production apparatus that uses a metal porous body for an electrode for electrolysis, the metal porous body having a porous metal skeleton and a metal oxide thin film formed on at least a part of the surface of the metal skeleton. In patent document 1, as a porous body substrate for forming a porous metal skeleton, for example, a resin foam such as foamed polyurethane is used. When such a resin foam is used, the skeleton of the obtained metal porous body tends to be large. Therefore, the use of the metal porous body is hardly advantageous from the viewpoint of improving the electrolytic performance, compared with the case of using carbon fibers having a wire diameter of about 8. Mu.m. Further, since the metal porous body has a three-dimensional network structure, it is considered that the electrolyte membrane is easily damaged.
Patent document 2 describes an electrochemical device using a titanium nonwoven fabric or a titanium particle sintered body as a power supply layer as an example. Patent document 2 describes that a metal other than titanium can be used for the power supply layer in the embodiment, but it is not studied as an example.
On the other hand, the water electrolysis apparatus is also generally required to be 1A/cm 2 The above-mentioned characteristics are stable when the device is operated for a long period of time. Non-patent document 1 describes a water electrolysis apparatus using a material such as Ni foam for an anode gas diffusion layer of a membrane electrode assembly. However, the current density of the water electrolysis apparatus was low, 0.5A/cm 2 Left and right.
As described above, the water electrolysis apparatuses described in patent document 1 and non-patent document 1 have room for further study from the viewpoint of durability. The electrochemical device described in patent document 2 has room for further study from the viewpoint of suppressing an increase in overvoltage. The present inventors have conducted intensive studies and as a result, have newly found that the use of a gas diffusion layer containing predetermined metal fibers is advantageous from the viewpoints of suppression of overvoltage increase and durability, and completed the present disclosure.
(summary of one mode of the disclosure)
An anode gas diffusion layer for a water electrolysis unit according to embodiment 1 of the present disclosure,
comprises metal fibers.
The metal fiber has a surface formed of nickel.
According to mode 1, a gas diffusion layer which suppresses an increase in overvoltage of a water electrolysis unit and has excellent durability can be provided.
In the present disclosure according to claim 2, for example, the anode gas diffusion layer for a water electrolysis unit according to claim 1, the metal fibers may have an average fiber diameter of 30 μm or less. According to the 2 nd aspect, the generated oxygen is easily discharged from the membrane electrode assembly.
In the 3 rd aspect of the present disclosure, for example, the anode gas diffusion layer for a water electrolysis unit according to the 1 st or 2 nd aspect may be substantially composed of only metal fibers. According to the 3 rd aspect, the gas diffusion layer more reliably has excellent durability.
In the present disclosure according to claim 4, for example, the anode gas diffusion layer for a water electrolysis unit according to any one of claims 1 to 3, the purity of the nickel may be 90 mass% or more. According to the 4 th aspect, the gas diffusion layer more reliably has excellent durability.
The water electrolysis unit according to claim 5 of the present disclosure includes:
an anode electrode,
Cathode, and cathode
An electrolyte membrane disposed between the anode and the cathode.
The anode includes an anode gas diffusion layer for a water electrolysis unit according to any one of aspects 1 to 4.
According to mode 5, the water electrolysis unit is easily excellent in durability.
In the present disclosure according to claim 6, for example, the water electrolysis unit according to claim 5, the anode may be provided with a catalyst layer containing a catalyst. The catalyst may contain nickel as an element. According to the 6 th aspect, a water electrolysis unit advantageous from the standpoint of reducing overvoltage can be provided.
In the 7 th aspect of the present disclosure, for example, the water electrolysis unit according to the 5 th or 6 th aspect, the electrolyte membrane may also include an anion exchange membrane. According to mode 7, oxygen gas generated at the anode and hydrogen gas generated at the cathode are not easily mixed.
The water electrolysis unit according to claim 8 of the present disclosure includes:
a diaphragm separating the first space from the second space,
An anode provided in the first space
And a cathode disposed in the second space.
The anode includes an anode gas diffusion layer for a water electrolysis unit according to any one of aspects 1 to 7.
According to the 8 th aspect, the water electrolysis unit easily has excellent durability.
In the 9 th aspect of the present disclosure, for example, the water electrolysis unit according to the 8 th aspect, the anode may further include a catalyst layer including a catalyst. The catalyst may contain nickel as an element. According to the 9 th aspect, a water electrolysis unit advantageous from the standpoint of reducing overvoltage can be provided.
The water electrolysis apparatus according to claim 10 of the present disclosure includes:
the water electrolysis unit according to any one of aspects 5 to 9; and
a voltage applicator connected to the anode and the cathode and applying a voltage between the anode and the cathode.
According to the 10 th aspect, the water electrolysis apparatus is easily provided with high durability.
Embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the following embodiments.
(embodiment 1)
Fig. 1 is a schematic diagram showing an example of a water electrolysis unit according to the present embodiment. As shown in fig. 1, the water electrolysis unit 2 includes an electrolyte membrane 31, an anode 100, and a cathode 200. The anode 100 includes an anode gas diffusion layer 1. The anode gas diffusion layer 1 includes metal fibers 10 described later. In the anode gas diffusion layer 1, metal fibers are, for example, intertwined with each other.
Fig. 2 is a diagram schematically showing an example of the metal fiber according to the present embodiment. As shown in fig. 2, the metal fiber 10 includes a portion 12. The portion 12 forms, for example, the surface of the metal fiber 10 and is made of nickel. The site 12 does not include an oxide film, for example. Since the anode gas diffusion layer 1 contains the metal fibers 10, the water electrolysis unit 2 can have excellent alkali resistance. Further, the anode gas diffusion layer 1 can have excellent electron conductivity.
In the present specification, "consisting of nickel" means that the purity of nickel is 90 mass% or more, for example. The purity of nickel in the portion 12 may be 92 mass% or more, 95 mass% or more, or 99 mass% or more. Thereby, the anode gas diffusion layer 1 can have high electron conductivity. The purity of nickel in the site 12 can be determined by, for example, X-ray photoelectron spectroscopy (XPS).
The region 12 may also be formed from a nickel plating.
The thickness of the portion 12 is not limited to a specific value. This value is, for example, 1 μm or more. The thickness of the portion 12 may be 5 μm or more, or 10 μm or more. The upper limit of the thickness of the portion 12 is not limited to a specific value. This value may be 30. Mu.m, or 10. Mu.m. By making the site 12 have such a thickness, the anode gas diffusion layer 1 can have excellent alkali resistance.
The metal fiber 10 may contain a metal other than nickel. Examples of such metals are iron, cobalt, aluminum, stainless steel, gold and platinum.
The average fiber diameter of the metal fibers 10 is, for example, 30 μm or less. Accordingly, the anode gas diffusion layer 1 has appropriate voids, and thus, it is easy to discharge gas such as oxygen generated by the operation of the water electrolysis apparatus. Further, the contact area of the anode gas diffusion layer 1 and the catalyst layer is easily increased, so that the efficiency of water electrolysis can be improved. The average fiber diameter of the metal fibers 10 may be 20 μm or less. The lower limit value of the average fiber diameter of the metal fibers 10 is not limited to a specific value. This value may be 5. Mu.m, or 10. Mu.m.
The average fiber diameter of the metal fibers 10 can be obtained by, for example, observing the metal fibers 10 with a Scanning Electron Microscope (SEM). Specifically, the maximum fiber diameter and the minimum fiber diameter of the metal fibers 10 are measured, and the average value thereof is defined as the fiber diameter of each metal fiber 10. The fiber diameter of the metal fiber 10 herein refers to the fiber width in the direction perpendicular to the extending direction of the fiber. By the above method, the fiber diameter was calculated for any 20 metal fibers 10, and the average value thereof was defined as the average fiber diameter.
The anode gas diffusion layer 1 is, for example, substantially composed of only metal fibers 10. The anode gas diffusion layer 1 may be a sintered body of the metal fiber 10. Thereby, the gas diffusion layer can have excellent electron conductivity. The anode gas diffusion layer 1 may contain components other than the metal fibers 10. The content of the component other than the metal fibers 10 in the anode gas diffusion layer 1 is, for example, 10 mass% or less.
The thickness of the anode gas diffusion layer 1 is not limited to a specific value. The value may be 50 μm or more and 1000 μm or less, or 100 μm or more and 500 μm or less.
The porosity of the anode gas diffusion layer 1 is not limited to a specific value. The value may be 50% by volume or more, 60% by volume or more, or 80% by volume or more. The upper limit value of the porosity of the anode gas diffusion layer 1 is not limited to a specific value. This value may be 90% by volume or 85% by volume. The anode gas diffusion layer 1 has such a porosity, and thus gases such as water and oxygen are more likely to diffuse. As a result, OH is easily supplied to the catalyst layer －－ . The porosity of the anode gas diffusion layer 1 can be determined by the method described in the examples.
The method of forming the site 12 is not limited to a specific method. The site 12 may also be formed by a method using vacuum techniques, plating, coating, or the like. Examples of methods using vacuum techniques are vacuum evaporation, DC sputtering, RF magnetron sputtering, pulsed Laser Deposition (PLD), atomic Layer Deposition (ALD), and Chemical Vapor Deposition (CVD).
As shown in fig. 1, the water electrolysis unit 2 includes an electrolyte membrane 31, an anode 100, and a cathode 200. The electrolyte membrane 31 is disposed between the anode 100 and the cathode 200, for example. The anode 100 includes the anode gas diffusion layer 1 described above. Since the water electrolysis unit 2 includes the anode gas diffusion layer 1, oxygen generated by the operation of the water electrolysis unit 2 is easily discharged from the membrane electrode assembly. The cathode 200 includes, for example, a cathode gas diffusion layer 34. The hydrogen gas generated in the catalyst layer 32, for example, is easily discharged from the membrane electrode assembly through the cathode gas diffusion layer 34.
The electrolyte membrane 31 may be an electrolyte membrane having ion conductivity. The electrolyte membrane 31 is not limited to a specific type. The electrolyte membrane 31 may also contain an anion exchange membrane. The electrolyte membrane 31 is configured such that, for example, oxygen gas generated at the anode 100 and hydrogen gas generated at the cathode 200 are not easily mixed.
Anode 100 includes, for example, catalyst layer 30. The catalyst layer 30 is responsible for generating oxygen, for example. The catalyst layer 30 may be provided on one main surface of the electrolyte membrane 31. The "main surface" refers to the surface of the electrolyte membrane 31 having the widest area. In the anode 100, the anode gas diffusion layer 1 may be provided on the catalyst layer 30. By supplying water and electrons to the catalyst layer 30, an oxygen generating reaction occurs.
The catalyst layer 30 may also contain a catalyst containing nickel as an element. In this case, the catalyst layer 30 and the anode gas diffusion layer 1 contain the same kind of metal. According to such a configuration, it is possible to provide a water electrolysis unit advantageous from the standpoint of reducing overvoltage.
The cathode 200 includes, for example, the catalyst layer 32. The catalyst layer 32 is responsible for generating hydrogen, for example. The catalyst layer 32 may be provided on the other main surface of the electrolyte membrane 31. That is, the catalyst layer 32 may be provided on a main surface opposite to the main surface on which the catalyst layer 30 is provided with respect to the electrolyte membrane 31. The catalyst that can be used in the catalyst layer 32 is not limited to a specific type. The catalyst may also be platinum. In the cathode 200, a porous and conductive gas diffusion layer 34 may be further provided on the catalyst layer 32. By supplying water and electrons to the catalyst layer 32, a hydrogen gas generation reaction occurs.
According to the above configuration, the water electrolysis unit 2 can have high durability.
(embodiment 2)
Fig. 3 is a cross-sectional view schematically showing an example of the water electrolysis apparatus according to the present embodiment.
The water electrolysis apparatus 3 includes the water electrolysis unit 2 and the voltage applicator 40. The water electrolysis unit 2 is the same as the water electrolysis unit 2 of embodiment 1, and therefore, the description thereof is omitted.
The voltage applicator 40 is connected to the anode 100 and the cathode 200 of the water electrolysis unit 2. The voltage applicator 40 is a device for applying a voltage between the anode 100 and the cathode 200 of the water electrolysis unit 2.
By the voltage applicator 40, the potential of the anode 100 becomes high and the potential of the cathode 200 becomes low. The voltage applicator 40 is not limited to a specific kind as long as it can apply a voltage between the anode 100 and the cathode 200. The voltage applicator 40 may also be a device that adjusts the voltage applied between the anode 100 and the cathode 200. Specifically, when the voltage applicator 40 is connected to a direct current power source such as a battery, a solar cell, or a fuel cell, the voltage applicator 40 includes a DC/DC converter. When the voltage applicator 40 is connected to an AC power source such as a commercial power source, the voltage applicator 40 includes an AC/DC converter. The voltage applicator 40 may be a power-type power source that adjusts the voltage applied between the anode 100 and the cathode 200 and the current flowing between the anode 100 and the cathode 200 so that the power supplied to the water electrolysis apparatus 3 becomes a predetermined set value.
According to the above configuration, the water electrolysis apparatus 3 can have high durability.
(embodiment 3)
Fig. 4 is a cross-sectional view schematically showing another example of the water electrolysis unit according to the present embodiment.
The water electrolysis unit 4 is, for example, an alkaline water electrolysis unit 4 using an alkaline aqueous solution. An alkaline aqueous solution is used for alkaline water electrolysis. Examples of the alkaline aqueous solution are aqueous potassium hydroxide solution and aqueous sodium hydroxide solution.
The alkaline water electrolysis unit 4 includes an anode 300 and a cathode 400. The alkaline water electrolysis unit 4 further comprises an electrolysis cell 70, a first space 50 and a second space 60. The anode 300 is disposed in the first space 50. The cathode 400 is disposed in the second space 60. The alkaline water electrolysis unit 4 has a separator 41. The diaphragm 41 is provided inside the electrolytic cell 70 to separate the first space 50 from the second space 60. Anode 300 includes, for example, a catalyst layer and a gas diffusion layer. The catalyst layer and the gas diffusion layer included in the anode 300 may be the same as the catalyst layer 30 and the anode gas diffusion layer 1 described in the first embodiment. The cathode 400 includes, for example, a catalyst layer and a gas diffusion layer. The catalyst layer and the gas diffusion layer included in the cathode 400 may be the same as the catalyst layer 32 and the gas diffusion layer 34 described in the first embodiment.
The separator 41 is, for example, a separator for alkaline water electrolysis.
The anode 300 may be disposed in contact with the separator 41, or may have a space between the anode 300 and the separator 41. The cathode 400 may be disposed in contact with the separator 41, or may have a space between the cathode 400 and the separator 41.
The alkaline water electrolysis unit 4 electrolyzes an alkaline aqueous solution to produce hydrogen and oxygen. An aqueous solution containing a hydroxide of an alkali metal or an alkaline earth metal may be supplied to the first space 50 of the alkaline water electrolysis unit 4. The alkaline aqueous solution may be supplied to the second space 60 of the alkaline aqueous electrolysis unit 4. Hydrogen and oxygen are produced by performing electrolysis while discharging an alkaline aqueous solution of a predetermined concentration from the first space 50 and the second space 60.
According to the above structure, the alkaline water electrolysis unit 4 can have high durability.
(embodiment 4)
Fig. 5 is a cross-sectional view schematically showing another example of the water electrolysis apparatus according to the present embodiment.
The water electrolysis apparatus 5 of the present embodiment is, for example, an alkaline water electrolysis apparatus 5 using an alkaline aqueous solution. The alkaline water electrolysis apparatus 5 includes an alkaline water electrolysis unit 4 and a voltage applicator 40. The alkaline water electrolysis unit 4 is the same as the alkaline water electrolysis unit 4 of embodiment 3, and therefore, the description thereof is omitted.
The voltage applicator 40 is connected to the anode 300 and the cathode 400 of the alkaline water electrolysis unit 4. The voltage applicator 40 is a device for applying a voltage to the anode 300 and the cathode 400 of the alkaline water electrolysis unit 4.
According to the above structure, the alkaline water electrolysis apparatus 5 can have high durability.
Examples
Hereinafter, the present disclosure will be described in more detail by way of examples. The following examples are examples of the present disclosure, and the present disclosure is not limited to the following examples.
Example 1
First, an electrode ink composed of an anode catalyst, a binder, and a solvent is prepared. As the anode catalyst, a Layered Double Hydroxide (LDH) containing Ni and Fe, i.e., ni—fe type LDH, was used. As the solvent, a mixed solvent of water and ethanol is used. The electrode ink was coated onto the anion exchange membrane by spray coating, thereby forming an anode catalyst layer. On the anode catalyst layer, as an anode gas diffusion layer, sintered nickel fiber NDF-17332-000 manufactured by Bekaert corporation, bekaert, and Bei Kaer tex were stacked. Thus, an anode is formed on the anion exchange membrane. The nickel fibers contained in the nickel fiber sintered body had an average fiber diameter of about 14 μm. Details of the materials used in the anode gas diffusion layer of example 1 are shown in table 1.
As the cathode gas diffusion layer, carbon paper TGP-H-120 manufactured by Toli corporation was used. The carbon paper was coated with Pt-supported carbon by spray coating, and a cathode catalyst layer was formed. The Pt-supported carbon was TEC10E50E, which is a Pt-supported carbon manufactured by noble metals in the field. Thus, a cathode in which a cathode catalyst layer was formed on the cathode gas diffusion layer was obtained. Next, the membrane electrode assembly of example 1 was produced by laminating the cathode catalyst layer in contact with the anion exchange membrane.
Fig. 6 is a view showing the result of observing the nickel fiber sintered body with a scanning electron microscope. As shown in fig. 6, the nickel fiber sintered body contains fibers.
Example 2
An anode of example 2 was produced in the same manner as in example 1 except that a sintered nickel fiber body bekicor 2ni 18-0.25 manufactured by Bei Kaer t was used as the anode gas diffusion layer. Bekicor is a registered trademark of Bei Kaer t.
Comparative example 1
An anode of comparative example 1 was produced in the same manner as in example 1 except that carbon paper TGP-H-120 manufactured by ori corporation was used as the anode gas diffusion layer. The average fiber diameter of the carbon fibers contained in the carbon paper was about 8 μm. A membrane electrode assembly of comparative example 1 was produced in the same manner as in example 1, except that the anode of comparative example 1 was used.
Comparative example 2
An anode of comparative example 2 was produced in the same manner as in example 1 except that 2GDL07N-030, which is Pt-plated Ti manufactured by Bei Kaer t was used as the anode gas diffusion layer. Pt-plated Ti is plated with platinum on the surface of the titanium fiber. The average fiber diameter of the Pt-plated Ti was about 22 μm. A membrane electrode assembly of comparative example 2 was produced in the same manner as in example 1, except that the anode of comparative example 2 was used.
(calculation of porosity)
Anode gas of example 1, comparative example 1 and comparative example 2The porosity of the diffusion layer was determined by gravimetric porosimetry. First, the apparent volume V and the dry weight W of the anode gas diffusion layer were measured, and the volume density ρ of the anode gas diffusion layer was calculated based on the following formula (1) a 。
ρ a =w/V (1)
Next, the porosity P of the anode gas diffusion layer is calculated based on the following formula (2). Furthermore, the true density ρ of the anode gas diffusion layer t The measurement was carried out by a gas displacement method. The results are shown in Table 1.
P ＝ (1－ρ a /ρ t ) X 100 type (2)
TABLE 1
| Example 1 | Example 2 | Comparative example 1 | Comparative example 2 | |
| Material of material | Ni | Ni | Carbon (C) | Pt plated Ti |
| Average fiber diameter (μm) | 14 | 22 | 8 | 22 |
| Porosity (vol%) | 85 | 60 | 80 | 74 |
| Thickness of anode gas diffusion layer (μm) | 220 | 250 | 370 | 300 |
| Initial voltage (V) | 1.563 | —— | 1.566 | 1.679 |
(measurement of cell Voltage)
The cell voltage of the water electrolysis cell was measured using the membrane electrode assemblies of example 1, comparative example 1 and comparative example 2. In the measurement, a water electrolysis cell evaluation apparatus manufactured by thermoelectric industry corporation was used, and the time change in voltage due to the gas generation of the water electrolysis cell was measured under the following measurement conditions. The results are shown in FIG. 7. In fig. 7, the cell voltage of the water electrolysis cell immediately after the start of the operation of the water electrolysis was defined as the initial voltage when the operation time of the water electrolysis cell was 0 hours. The measurement results of the initial voltage are shown in table 1.
[ measurement conditions ]
Supply liquid: 1 mol/l KOH aqueous solution
Liquid supply rates to the anode and cathode electrodes, respectively: 10cm 3 Per minute
Temperature of the water electrolysis unit: 80 DEG C
Pressure: atmospheric pressure
Current density: 1A/cm 2
Electrode effective surface area: 1cm 2
Fig. 7 is a graph showing the result of the change in voltage with time caused by the gas generation of the water electrolysis unit. The vertical axis represents cell voltage. The horizontal axis represents the operation time of the water electrolysis unit. As shown in fig. 7, in example 1, even if the operation time exceeds 1200 hours, the cell voltage is low. The water electrolysis cell of example 1 was found to have excellent durability.
As shown in Table 1, the current density was 1A/cm 2 The initial voltage of the water electrolysis cell of example 1 was 1.563V. On the other hand, the initial voltage of the water electrolysis cell of comparative example 2 was 1.679V. The current density was 1A/cm 2 In this case, the initial voltage of the water electrolysis cell of example 1 was lower than that of the water electrolysis cell of comparative example 2. It was found that the water electrolysis cell using the gas diffusion layer of example 1 had excellent electrolysis performance.
Here, the theoretical voltage of water electrolysis was 1.23V. In example 1, the overvoltage with respect to the theoretical voltage in water electrolysis was 0.333V. In comparative example 2, the overvoltage with respect to the theoretical voltage in water electrolysis was 0.449V. In example 1, the overvoltage was reduced by 0.116V (116 mV) as compared with comparative example 2. In example 1, the overvoltage was reduced by 26% compared with comparative example 2. In example 1, a nickel fiber sintered body was used for the anode gas diffusion layer. It is found that the water electrolysis cell according to example 1 can suppress an increase in overvoltage.
(measurement of contact resistivity of anode gas diffusion layer)
The contact resistivity of the anode gas diffusion layers used in example 1 and comparative example 2 was measured. The contact resistivity was measured using a tensile compression tester manufactured by the company of the product of the field and a low resistance meter 3566 manufactured by the company of the crane electric machine. The contact resistivity was calculated by sandwiching the anode gas diffusion layer between jigs, measuring the resistance value, and subtracting the resistance value of the jigs. Specifically, the anode gas diffusion layer processed to have a diameter of 30mm was placed on a measurement jig, and the displacement and resistance value when a load of up to 4kN was measured, and the resistance value measured in the state where the anode gas diffusion layer was not present was subtracted. At this time, the change in contact resistivity of the anode gas diffusion layer with respect to pressure was measured, and the result is shown in fig. 8.
Fig. 8 is a graph showing the results of measuring the change in contact resistivity of the anode gas diffusion layer with respect to pressure. In FIG. 8, the vertical axis represents the contact resistivity [ mΩ·cm ] of the anode gas diffusion layer 2 ]. The horizontal axis represents pressure [ MPa ]]. The contact resistivity of the anode gas diffusion layer used in example 1 was 0.2mΩ·cm at a pressure of 1MPa 2 . The contact resistivity of the anode gas diffusion layer used in comparative example 2 was 0.4mΩ·cm at a pressure of 1MPa 2 . Therefore, the contact resistivity of the anode gas diffusion layer used in example 1 was 0.2mΩ·cm smaller than that of the anode gas diffusion layer used in comparative example 2 2 . The main reason for this is considered to be that the metal species contained in the anode gas diffusion layer are different in example 1 and comparative example 2.
Based on the measurement result of the contact resistivity of the anode gas diffusion layer, in example 1 and comparative example 2, the difference between the contact resistivity of the anode gas diffusion layers was 0.2mΩ·cm 2 . From the difference in contact resistivity, it is expected that the difference in overvoltage between the water electrolysis cell of example 1 and the water electrolysis cell of comparative example 2 is 1A/cm in current density 2 At 0.2[ mΩ·cm ] 2 ]×1[A/cm 2 ]=0.2 mV. On the other hand, as described above, the difference between the overvoltage of the water electrolysis cell of example 1 and the overvoltage of the water electrolysis cell of comparative example 2 was 116mV. Thus, in example 1 and comparative example 2, the difference between the overvoltage is larger than the value expected from the contact resistivity. In example 1, the anode gas diffusion layer contains nickel. In addition, in example 1, the catalyst layer also contains a catalyst containing nickel as a constituent element. It is presumed that since the anode gas diffusion layer and the catalyst layer contain the same kind of metal, the difference in overvoltage is larger than the value predicted from the contact resistivity.
(measurement of Current Density-Voltage characteristics of Water electrolysis cell)
Use examplesThe membrane electrode assemblies of 1 and example 2 were used to produce water electrolysis units. Except for the following measurement conditions, the current density-voltage characteristics of the water electrolysis cell were measured under the same measurement conditions as described above (measurement of cell voltage). Controlling the applied current by an external power supply device to make the current density from 0A/cm 2 Stepwise up to 2A/cm 2 The current density-voltage characteristics of the water electrolysis cell were thus measured.
At a current density of 1A/cm 2 In this case, the ratio X of the cell voltage of the water electrolysis cell of example 1 to the cell voltage of the water electrolysis cell of example 2 1 1.01. At a current density of 2A/cm 2 In this case, the ratio X of the cell voltage of the water electrolysis cell of example 1 to the cell voltage of the water electrolysis cell of example 2 2 1.00. As shown in table 1, the average fiber diameter and porosity values of the nickel fiber sintered body used in example 1 and the nickel fiber sintered body used in example 2 were different. That is, in embodiments 1 and 2, the structure of the anode gas diffusion layer is different. However, according to a current density of 1A/cm 2 Ratio X at time 1 And a current density of 2A/cm 2 Ratio X at time 2 It can be understood that the cell voltage of the water electrolysis cell of example 1 is the same as the cell voltage of the water electrolysis cell of example 2. From these results, it is assumed that the difference in the structure of the anode gas diffusion layer is less likely to affect the cell voltage.
Industrial applicability
One embodiment of the present disclosure can be used for a gas diffusion layer having higher oxidation degradation resistance than before in a water electrolysis reaction.
Description of the reference numerals
1 anode gas diffusion layer
2. 4 water electrolysis unit
3. 5 water electrolysis device
10 Metal fiber
12 parts
30. 32 catalyst layer
31 electrolyte membrane
34 gas diffusion layer
40 voltage applicator
41 diaphragm
50. 60 space
70 electrolytic cell
100. 300 anode
200. 400 cathode
Claims (10)
1. An anode gas diffusion layer for a water electrolysis unit,
is provided with a metal fiber which is made of a metal material,
the metal fiber has a surface formed of nickel.
2. The anode gas diffusion layer for a water electrolysis unit according to claim 1,
the metal fibers have an average fiber diameter of 30 μm or less.
3. The anode gas diffusion layer for a water electrolysis unit according to claim 1 or 2,
the anode gas diffusion layer for the water electrolysis unit is substantially composed of only the metal fibers.
4. The anode gas diffusion layer for a water electrolysis unit according to claim 1,
the purity of the nickel is 90 mass% or more.
5. A water electrolysis unit is provided with:
an anode electrode,
Cathode, and cathode
An electrolyte membrane disposed between the anode and the cathode,
the anode comprising the anode gas diffusion layer for a water electrolysis unit according to claim 1.
6. The water electrolysis unit according to claim 5,
the anode further comprises a catalyst layer containing a catalyst containing nickel as a constituent element.
7. The water electrolysis unit according to claim 5,
the electrolyte membrane comprises an anion exchange membrane.
8. A water electrolysis unit is provided with:
a diaphragm separating the first space from the second space,
An anode provided in the first space
A cathode disposed in the second space,
the anode comprising the anode gas diffusion layer for a water electrolysis unit according to claim 1.
9. The water electrolysis unit according to claim 8,
the anode further comprises a catalyst layer containing a catalyst containing nickel as a constituent element.
10. A water electrolysis apparatus is provided with:
the water electrolysis unit according to claim 5
The voltage-applying device is provided with a voltage-applying device,
the voltage applicator is connected to the anode and the cathode and applies a voltage between the anode and the cathode.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
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| JP2021-084502 | 2021-05-19 | ||
| JP2022068974 | 2022-04-19 | ||
| JP2022-068974 | 2022-04-19 | ||
| PCT/JP2022/019752 WO2022244644A1 (en) | 2021-05-19 | 2022-05-10 | Anode gas diffusion layer for water electrolysis cells, water electrolysis cell, and water electrolysis device |
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| CN117321249A true CN117321249A (en) | 2023-12-29 |
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