Electrolytic cell and electrolytic device

Abstract

To provide an electrolysis cell and an electrolysis device having better electrolysis performance. [Solution] The electrolysis cell includes an ion exchange membrane, a current collector made of a plurality of fibers formed into a sheet and provided on the surface of the ion exchange membrane, a binder layer covering the surface of each fiber, and an electrode catalyst layer including catalyst particles at least a part of which protrudes from the surface of the binder layer. At least a part of the medium particles protrudes from the surface of the binder layer. This increases the surface area of ​​the exposed part of the catalyst particles, thereby increasing the contact area with the electrolyte.

Description

[Technical field]

[0001] The present disclosure relates to electrolysis cells and electrolysis devices. [Background technology]

[0002] Water electrolysis devices (electrolysis devices) are known as devices for generating hydrogen. In this type of device, an electrolytic cell separated into a cathode chamber and an anode chamber by an ion exchange membrane is filled with water, and water is electrolyzed by supplying electricity to the cathode and anode. In the cathode chamber, hydrogen is generated by a reaction between water and electrons. The hydroxide ions produced by this reaction permeate the ion exchange membrane and reach the anode chamber. In the anode chamber, oxygen and water are generated from these hydroxide ions. By continuing this reaction, large amounts of hydrogen can be obtained.

[0003] A power supply body is disposed on both sides of the ion exchange membrane in the thickness direction, between the anode and the cathode. A specific example of a power supply body is described in Patent Document 1 below. In the device according to Patent Document 1 below, a barrier layer is provided on the surface of the power supply body to protect catalytic substances such as platinum. The barrier layer is formed of a polymer binder, a conductive ceramic material, and the like. It is believed that this can suppress early corrosion of the power supply body during the progress of the electrolytic reaction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6430969 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the corrosion resistance is prioritized as described above, the contact area between the catalytic material and the electrolyte is reduced by the amount of the barrier layer provided, which poses a problem that the desired electrolysis performance cannot be obtained.

[0006] The present disclosure has been made to solve the above problems, and has an object to provide an electrolysis cell and an electrolysis device having better electrolysis performance. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention comprises an ion exchange membrane according to the present disclosure, a power supply body formed on the surface of the ion exchange membrane and consisting of a plurality of fibers formed into a sheet shape, a binder layer covering the surface of each of the fibers, and an electrode catalyst layer including catalyst particles at least a portion of which protrudes from the surface of the binder layer.

[0008] The electrolysis device according to the present disclosure includes the electrolysis cell described above, an electrolyte supply unit that supplies an electrolyte to the electrolysis cell, and a power supply unit that applies a voltage to the electrolysis cell. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an electrolysis cell and an electrolysis device having better electrolysis performance. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of an electrolysis device according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing a configuration of an electrolysis cell according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 is an exploded perspective view showing a configuration of an electrolysis cell according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a close-up view of the fibers of the cathode catalyst layer according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a close-up view of the fibers of an anode catalyst layer according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a schematic diagram showing the state of catalyst particles in an electrode catalyst layer according to an embodiment of the present disclosure. [Figure 7] 4 is a graph showing the relationship between the particle size and exposed area of ​​catalyst particles in an electrode catalyst layer according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an electrolysis cell and an electrolysis device according to an embodiment of the present disclosure will be described with reference to the drawings. In the following description, components having the same or similar functions are denoted by the same reference numerals. In the present disclosure, "facing" means that two members overlap when viewed in a certain direction, and may also include a case where another member (e.g., another layer) exists between the two members.

[0012] First, the Z direction, the X direction, and the Y direction are defined. The Z direction is a direction from the first separator 41 to the second separator 42 described later. The X direction is a direction intersecting (for example, perpendicular to) the Z direction, and is a direction from the center C of the membrane electrode assembly 43 described later to one end of the membrane electrode assembly 43. The Y direction is a direction intersecting (for example, perpendicular to) the Z direction and the X direction, and is, for example, the depth direction of the paper in FIG. 2. In this disclosure, "area" means an area when viewed in the Z direction (i.e., an area extending in the X direction and the Y direction). In addition, in this disclosure, "external size" means an external size when viewed in the Z direction. In other words, "external size" and "area" may mean substantially the same thing, and may be appropriately read as one another.

[0013] <1. Configuration of electrolysis device> 1 is a schematic diagram showing the overall configuration of an electrolysis device 1 of this embodiment. The electrolysis device 1 is, for example, a device that generates hydrogen by electrolyzing water contained in an electrolytic solution. The electrolysis device 1 is, for example, an anion exchange membrane (AEM) type electrolysis device. However, the electrolysis device 1 is not limited to the above example, and may be a different type of electrolysis device, such as a device that electrolytically reduces carbon dioxide.

[0014] The electrolysis device 1 includes, for example, an electrolysis cell stack 10, an electrolyte supply unit 20, and a power supply unit 30.

[0015] (Electrolysis cell stack) The electrolysis cell stack 10 is an assembly of a plurality of electrolysis cells 11. For example, the electrolysis cell stack 10 is formed by arranging a plurality of electrolysis cells 11 in one direction. Each electrolysis cell 11 includes a cathode chamber Sa and an anode chamber Sb. The electrolysis cells 11 will be described in detail later.

[0016] (Electrolyte supply section) The electrolyte supply unit 20 is a supply unit that supplies an electrolyte to each electrolytic cell 11. The electrolyte is, for example, pure water or an alkaline aqueous solution. The electrolyte supply unit 20 includes a cathode side supply unit 20a and an anode side supply unit 20b.

[0017] The cathode side supply unit 20a is a supply unit that supplies the electrolytic solution to the cathode chamber Sa of each electrolytic cell 11. The cathode side supply unit 20a includes, for example, a hydrogen gas-liquid separator 21, a first pump 22, a hydrogen recovery unit 23, a first electrolytic solution supply unit 24, and piping lines L1 and L2.

[0018] The hydrogen-gas-liquid separator 21 stores the electrolytic solution. A supply port of the hydrogen-gas-liquid separator 21 is connected to the cathode chamber Sa of the electrolytic cell 11 via a piping line L1. The first pump 22 is provided midway along the piping line L1, and sends the electrolytic solution stored in the hydrogen-gas-liquid separator 21 toward the cathode chamber Sa of the electrolytic cell 11.

[0019] A return port of the hydrogen gas-liquid separator 21 is connected to the cathode chamber Sa of the electrolytic cell 11 via a piping line L2. An electrolytic solution containing hydrogen produced in the electrolytic cell 11 flows from the electrolytic cell 11 into the hydrogen gas-liquid separator 21. The hydrogen gas-liquid separator 21 has a gas-liquid separation section that separates the hydrogen contained in the electrolytic solution. The hydrogen separated from the electrolytic solution by the hydrogen gas-liquid separator 21 is recovered by a hydrogen recovery section 23. The hydrogen gas-liquid separator 21 is replenished with electrolytic solution from a first electrolytic solution supply section 24.

[0020] On the other hand, the anode side supply unit 20b is a supply unit that supplies the electrolytic solution to the anode chamber Sb of each electrolytic cell 11. The anode side supply unit 20b includes, for example, an oxygen gas-liquid separator 26, a second pump 27, an oxygen recovery unit 28, a second electrolytic solution supply unit 29, and piping lines L3 and L4.

[0021] The oxygen-gas-liquid separator 26 stores the electrolytic solution. A supply port of the oxygen-gas-liquid separator 26 is connected to the anode chamber Sb of the electrolytic cell 11 via a piping line L3. The second pump 27 is provided in the middle of the piping line L3 and sends the electrolytic solution stored in the oxygen-gas-liquid separator 26 toward the anode chamber Sb of the electrolytic cell 11.

[0022] A return port of the oxygen-gas-liquid separator 26 is connected to the anode chamber Sb of the electrolytic cell 11 via a piping line L4. The electrolyte containing oxygen produced in the electrolytic cell 11 flows from the electrolytic cell 11 into the oxygen-gas-liquid separator 26. The oxygen-gas-liquid separator 26 has a gas-liquid separation section that separates the oxygen contained in the electrolyte. The oxygen separated from the electrolyte by the oxygen-gas-liquid separator 26 is recovered by an oxygen recovery section 28. The electrolyte is replenished to the oxygen-gas-liquid separator 26 from a second electrolyte supply section 29.

[0023] (Power supply part) The power supply unit 30 is a DC power supply device that applies a voltage to the electrolytic cell 11. The power supply unit 30 applies a DC voltage required for electrolysis of the electrolyte between the anode and cathode of the electrolytic cell 11.

[0024] <2. Structure of electrolysis cell> <2.1 Basic structure of electrolysis cell> Next, the electrolytic cell 11 will be described in detail. 2 is a cross-sectional view that diagrammatically illustrates the electrolysis cell 11. The electrolysis cell 11 includes, for example, a first separator 41, a second separator 42, and a membrane electrode assembly 43.

[0025] (First separator) The first separator 41 is a member that defines one side of the internal space S of the electrolysis cell 11. The internal space S is a space that includes a cathode chamber Sa and an anode chamber Sb described below. The first separator 41 is, for example, in the shape of a rectangular plate, and is made of a metal member. A negative voltage is applied to the first separator 41 from the power supply unit 30 via, for example, a first current collector 61 (see FIG. 3) described below.

[0026] The first separator 41 has a first end 41e1 (e.g., a lower end) and a second end 41e2 (e.g., an upper end) located on the opposite side to the first end 41e1. The above-mentioned piping line L1 is connected to the first end 41e1 of the first separator 41. The above-mentioned piping line L2 is connected to the second end 41e2 of the first separator 41. The first separator 41 has a first inner surface 41a facing the cathode chamber Sa described later. The first inner surface 41a is formed with a first flow path FP1 through which the electrolytic solution supplied from the piping line L1 flows. The first flow path FP1 is, for example, a groove provided in the first inner surface 41a. The electrolytic solution that has flowed through the first flow path FP1 is discharged to the outside of the electrolytic cell 11 through the piping line L2. Note that each structure (e.g., flow path structure, etc.) shown in FIG. 2 is merely an example and does not limit the contents of this embodiment. For example, various structures can be used for the flow path structure depending on the size, purpose, and usage environment of the device. This also applies to the structures shown in the other figures.

[0027] (Second separator) The second separator 42 is disposed with an internal space S between it and at least a part of the first separator 41, and is a member that defines the other side of the internal space S. The second separator 42 is, for example, a rectangular plate and is made of a metal member. A positive voltage is applied to the second separator 42 from the power supply unit 30 via a second current collector 62 (see FIG. 3 ), which will be described later. The first separator 41 and the second separator 42 included in the same electrolytic cell 11 form the electrolytic cell 40 of the electrolytic cell 11 as a pair of separators.

[0028] The second separator 42 has a first end 42e1 (e.g., a lower end) and a second end 42e2 (e.g., an upper end) located on the opposite side to the first end 42e1. The above-mentioned piping line L3 is connected to the first end 42e1 of the second separator 42. The above-mentioned piping line L4 is connected to the second end 42e2 of the second separator 42. The second separator 42 has a second inner surface 42a facing the anode chamber Sb described later. The second inner surface 42a is formed with a second flow path FP2 through which the electrolytic solution supplied from the piping line L3 flows. The second flow path FP2 is, for example, a groove provided in the second inner surface 42a. The electrolytic solution that has flowed through the second flow path FP2 is discharged to the outside of the electrolytic cell 11 through the piping line L4.

[0029] For convenience of explanation, the first separator 41 has a groove for a flow path (first flow path FP1), and the second separator 42 has a groove for a flow path (second flow path FP2). However, for example, the first separator 41 of the electrolysis cell 11 included in the electrolysis cell stack 10 (see FIG. 1) may be a bipolar plate having a similar groove for a flow path (first flow path FP1, shown by a two-dot chain line in FIG. 2) on the surface 41b opposite to the first inner surface 41a in addition to the first inner surface 41a. The second separator 42 of the electrolysis cell 11 included in the electrolysis cell stack 10 may be a bipolar plate having a similar groove for a flow path (second flow path FP2, shown by a two-dot chain line in FIG. 2) on the surface 42b opposite to the second inner surface 42a in addition to the second inner surface 42a. The grooves for a flow path provided on both sides of the first separator 41 may have different shapes and arrangements. Furthermore, the flow path grooves provided on both sides of the second separator 42 may have different shapes and arrangements.

[0030] The membrane electrode assembly (MEA) 43 is a structure in which an ion exchange membrane, a catalyst, and a power supply are assembled. The membrane electrode assembly 43 is disposed between a first separator 41 and a second separator 42, and is located in an internal space S. The membrane electrode assembly 43 includes, for example, a first ion exchange membrane 51, a second ion exchange membrane 52, an ionomer layer 53, a cathode catalyst layer 54, and an anode catalyst layer 56.

[0031] (First ion exchange membrane) The first ion exchange membrane 51 is a membrane that selectively transmits ions. The first ion exchange membrane 51 is, for example, a solid polymer electrolyte membrane. The first ion exchange membrane 51 is, for example, an anion exchange membrane (AEM) that is hydroxide ion conductive. However, the first ion exchange membrane 51 is not limited to the above example, and may be an ion exchange membrane of a type different from the above example. The first ion exchange membrane 51 is, for example, a rectangular sheet. The outer size of the first ion exchange membrane 51 is smaller than the outer size of the first separator 41 or the second separator 42. The first ion exchange membrane 51 is disposed between the first separator 41 and the second separator 42, and is located in the above-mentioned internal space S. The first ion exchange membrane 51 has a first surface 51a that faces the first inner surface 41a of the first separator 41, and a second surface 51b that is located on the opposite side to the first surface 51a. In the internal space S, between the first surface 51a of the first ion exchange membrane 51 and the first inner surface 41a of the first separator 41, a cathode chamber Sa is defined.

[0032] In the cathode chamber Sa, when a voltage is applied to the electrolytic cell 11, the following chemical reaction occurs, and hydrogen is produced from the electrolytic solution. In this application, "XX is produced" may also include cases where other substances are produced simultaneously with the production of XX. The hydroxide ions produced in the cathode chamber Sa pass through the membrane electrode assembly 43 and move from the cathode chamber Sa to the anode chamber Sb. 2H2O+2e-→H2+2OH- …(Chemical 1)

[0033] (Second ion exchange membrane) The second ion exchange membrane 52 is a membrane that selectively transmits ions. The second ion exchange membrane 52 is, for example, a solid polymer electrolyte membrane. The second ion exchange membrane 52 is, for example, an anion exchange membrane that is hydroxide ion conductive. However, the second ion exchange membrane 52 is not limited to the above example, and may be an ion exchange membrane of a type different from the above example. The second ion exchange membrane 52 is, for example, a rectangular sheet. The outer size of the second ion exchange membrane 52 is smaller than the outer size of the first separator 41 or the second separator 42. For example, the outer size of the second ion exchange membrane 52 is the same as the outer size of the first ion exchange membrane 51. The second ion exchange membrane 52 is disposed between the first separator 41 and the second separator 42, and is located in the above-mentioned internal space S. The second ion exchange membrane 52 has a third surface 52a facing the second inner surface 42a of the second separator 42, and a fourth surface 52b located on the opposite side to the third surface 52a. In the internal space S, an anode chamber Sb is defined between the third surface 52a of the second ion exchange membrane 52 and the second inner surface 42a of the second separator 42.

[0034] In the anode chamber Sb, when a voltage is applied to the electrolytic cell 11, the following chemical reaction occurs, producing oxygen from the electrolyte. 2OH-→1 / 2O2+H2O+2e- …(Chemical 2)

[0035] As a result, the following chemical reactions occur in the electrolytic cell 11 as a whole: H2O→H2+1 / 2O2…(Chemical 3)

[0036] In the present disclosure, ordinal numbers such as "first" and "second" are attached to the names of components for convenience of explanation. For example, the names "third" and "fourth" do not assume that the names "first" and "second" exist for the same component. In this embodiment, the names "third surface 52a" and "fourth surface 52b" of the second ion exchange membrane 52 do not assume that the second ion exchange membrane 52 has a first surface and a second surface. For this reason, the names "third surface 52a" and "fourth surface 52b" may be read as the "first surface 52a" and "second surface 52b" of the second ion exchange membrane 52.

[0037] In this embodiment, the first ion exchange membrane 51 and the second ion exchange membrane 52 are integrated with the second surface 51b of the first ion exchange membrane 51 facing the fourth surface 52b of the second ion exchange membrane 52. In the present disclosure, "the first ion exchange membrane 51 and the second ion exchange membrane 52 are integrated" is not limited to the case where the first ion exchange membrane 51 and the second ion exchange membrane 52 are directly bonded to each other, but may also include the case where another layer (for example, an ionomer layer 53 described later) exists between the first ion exchange membrane 51 and the second ion exchange membrane 52.

[0038] The materials of the first ion exchange membrane 51 and the second ion exchange membrane 52 may be the same or different from each other. For example, the materials of the first ion exchange membrane 51 and the second ion exchange membrane 52 are selected as follows. That is, since no oxidation reaction occurs in the cathode chamber Sa, the first ion exchange membrane 51 does not need to have high oxidation resistance. For this reason, for example, a membrane made of a material having a higher ion conductivity than the second ion exchange membrane 52 is used as the first ion exchange membrane 51. On the other hand, since an oxidation reaction occurs in the anode chamber Sb, it is preferable that the second ion exchange membrane 52 has high oxidation resistance. For this reason, for example, a membrane made of a material having a higher oxidation resistance than the first ion exchange membrane 51 is used as the second ion exchange membrane 52.

[0039] An example of a "membrane with high ionic conductivity" is a membrane that contains a polystyrene-based or tetraphenyl-based composition in the main chain and an imidazolium group or a quaternary ammonium group in the side chain. An example of a "membrane with high oxidation resistance" is a membrane that contains a polysulfone-based or bromobutylstyrene-based composition.

[0040] (Ionomer layer) The ionomer layer 53 is a layer for bonding the first ion exchange membrane 51 and the second ion exchange membrane 52. The ionomer layer 53 is a layer through which hydroxide ions can pass. The ionomer layer 53 is provided between the second surface 51b of the first ion exchange membrane 51 and the fourth surface 52b of the second ion exchange membrane 52. For example, the ionomer layer 53 is provided over the entire area of ​​the second surface 51b of the first ion exchange membrane 51 and the entire area of ​​the fourth surface 52b of the second ion exchange membrane 52. The thickness of the ionomer layer 53 is, for example, 10 nm or more and 10 μm or less. In this embodiment, the first ion exchange membrane 51 and the second ion exchange membrane 52 are integrated via the ionomer layer 53.

[0041] (Cathode catalyst layer) The cathode catalyst layer 54 is a layer that promotes the chemical reaction in the cathode chamber Sa described above. The cathode catalyst layer 54 is, for example, a rectangular sheet. In this embodiment, the outer size of the cathode catalyst layer 54 is smaller than the outer size of the first ion exchange membrane 51. The cathode catalyst layer 54 is disposed in the cathode chamber Sa and is adjacent to the first ion exchange membrane 51. In this application, the term "adjacent" is not limited to the case where two members are adjacent to each other independently, but may also include the case where at least a part of one of the two members is embedded in the other member. In this embodiment, the cathode catalyst layer 54 is provided on the first surface 51a of the first ion exchange membrane 51. A negative voltage is applied to the cathode catalyst layer 54 from the power supply unit 30 via the first separator 41, and the cathode catalyst layer 54 functions as a part of the cathode 47 of the electrolysis cell 11.

[0042] 4, the cathode catalyst layer 54 has a cathode power supplier 71, a binder layer 72, and cathode catalyst particles 73. The cathode power supplier 71 is an electrical connection part that transmits the voltage applied to the first separator 41 to the cathode catalyst layer 54 itself. The cathode power supplier 71 has a mesh shape formed of, for example, carbon fibers. In other words, a plurality of carbon fibers are entangled to form the sheet-like cathode power supplier 71.

[0043] The surface of each of these carbon fibers is covered with a binder layer 72. The binder layer 72 is a material for fixing the cathode catalyst particles 73 to the surface of the carbon fibers. Specifically, a fluorine-based resin material is preferably used as the binder layer 72. In particular, polytetrafluoroethylene (PTFE (registered trademark)), fluoroethylene vinyl ether (FEVE), and polyvinylidene fluoride (PVdF) are preferably used. This is because these resin materials can maintain the adhesiveness between substances, that is, the bonding strength, at a high level for a long period of time. In particular, polyvinylidene fluoride exhibits particularly good bonding strength in an alkaline environment, and is therefore effective when the electrolyte is an alkaline aqueous solution (for example, an aqueous potassium hydroxide solution).

[0044] The cathode catalyst particles 73 are fixed to the fiber surface of the cathode current collector 71 by the binder layer 72. Specifically, as shown in FIG. 6, the cathode catalyst particles 73 exist as individual particles or as aggregates of these individual particles. Most of the cathode catalyst particles 73 protrude from the surface of the binder layer 72. That is, at least a part of the surface of the granular cathode catalyst particles 73 protrudes further outward than the outer surface of the binder layer 72. As shown in FIG. 6, when the particle diameter of the cathode catalyst particles 73 is D (radius r), the surface area A of the particles exposed from the binder layer 72 having a thickness t is calculated as A=2πr(2r-t).

[0045] However, since the actual particle diameter D of the cathode catalyst particles 73 varies by about 1σ / D=0.1 to 0.4 with respect to the average particle diameter σ, the total value of the exposed area needs to be obtained by statistical simulation. In other words, since the surface area of ​​the catalyst exposed from the binder layer varies depending on the variation in particle diameter, it is necessary to perform a statistical calculation to determine what percentage of the total surface area of ​​the cathode catalyst particles 73 is exposed from the binder film. In the case of a catalyst, since 1σ / D varies in the range of about 0.1 to 0.4 with respect to the average particle diameter D, the ratio of the surface area of ​​the exposed part of the cathode catalyst particles 73 to the total surface area (total surface area of ​​the binder layer 72) is as shown in FIG. 7 as an example of the calculation result. Specifically, considering the electrolysis performance and life of the cathode catalyst particles 73, it is desirable that the surface area of ​​the cathode catalyst particles 73 exposed from the binder layer 72 is at least in the range of 20% to 80% of the total surface area. More desirably, this surface area ratio is 40% to 60%. Most preferably, this surface area percentage is 50%.

[0046] The "average particle size" referred to here is a value obtained by, for example, a laser diffraction particle size distribution measurement method. Specific examples of measuring instruments that use this type of method include the "SALD series manufactured by Shimadzu Corporation."

[0047] The thickness of the binder layer 72 is preferably 20 to 100% of the average particle size. Furthermore, considering the balance between electrode performance and life, it is preferable that 40 to 60% of the total surface area is in contact with the electrolyte, so the thickness of the binder layer 72 in this case is preferably 40 to 65% of the average particle size.

[0048] When the cathode catalyst particles 73 are aggregates, the index for controlling the exposed area is the same as that for the single particle described above. That is, when the aggregate particle size=D (radius r), the surface area A of the aggregate exposed from the binder layer 72 with thickness t is calculated as A=2kπr(2r-t). Here, k is a proportionality constant, which is appropriately set depending on the primary particle size of the particles and the aggregate size.

[0049] The material of the cathode catalyst particles 73 includes one or more of nickel, nickel alloy, cerium oxide, lanthanum oxide, and platinum. Platinum-supported carbon is particularly preferably used as the cathode catalyst particles 73. In this disclosure, "XX oxide" may include other materials other than XX and oxygen.

[0050] In forming the above-described cathode catalyst layer 54, for example, a method is used in which the cathode power supplier 71 is immersed in a slurry containing the cathode catalyst particles 73 and the substance that forms the binder layer 72. At this time, by adjusting the volume fraction of the substance that forms the cathode catalyst particles 73 and the binder layer 72, it becomes possible to expose the cathode catalyst particles 73 from the surface of the binder layer 72 as described above, and to control the ratio of the surface area of ​​the exposed portion within the above numerical range.

[0051] (Anode catalyst layer) The anode catalyst layer 56 is a layer that promotes the chemical reaction in the anode chamber Sb. The anode catalyst layer 56 is, for example, a rectangular sheet. In this embodiment, the outer size of the anode catalyst layer 56 is smaller than the outer size of the second ion exchange membrane 52. The anode catalyst layer 56 is disposed in the anode chamber Sb and is adjacent to the second ion exchange membrane 52. Note that, for example, a part of the anode catalyst layer 56 may be embedded in the surface portion of the second ion exchange membrane 52. In this embodiment, the anode catalyst layer 56 is provided on the third surface 52a of the second ion exchange membrane 52. For example, the anode catalyst layer 56 is formed by applying the material of the anode catalyst layer 56 to the third surface 52a of the second ion exchange membrane 52. A positive voltage is applied to the anode catalyst layer 56 from the power supply unit 30 via the second separator 42, and the anode catalyst layer 56 functions as a part of the anode 48 of the electrolysis cell 11.

[0052] 5, the anode catalyst layer 56 has an anode power supplier 81, a binder layer 82, and anode catalyst particles 83. The anode power supplier 81 is an electrical connection part that transmits the voltage applied to the second separator 42 to the anode catalyst layer 56 itself. The anode power supplier 81 has a mesh shape formed of, for example, stainless steel fibers. In other words, a plurality of stainless steel fibers are entangled to form the sheet-like anode power supplier 81.

[0053] The surface of each of these fibers is covered with a binder layer 82. The binder layer 82 is a substance for fixing the anode catalyst particles 83 to the surface of the stainless steel fibers. As with the cathode catalyst layer 54, a fluororesin material is preferably used for the binder layer 82. In particular, polytetrafluoroethylene (PTFE (registered trademark)), fluoroethylene vinyl ether (FEVE), and polyvinylidene fluoride (PVdF) are preferably used. This is because these resin materials can maintain the adhesiveness between substances, that is, the bonding strength, at a high level for a long period of time.

[0054] The anode catalyst particles 83 are fixed to the fiber surface of the anode current collector 81 by the binder layer 82. Specifically, as shown in FIG. 6, the anode catalyst particles 83 exist as a single particle or an aggregate of these particles. Most of the anode catalyst particles 83 protrude from the surface of the binder layer 82. That is, at least a part of the surface of the granular anode catalyst particles 83 protrudes further outward than the outer surface of the binder layer 82. It is desirable that the ratio of the surface area of ​​the exposed part of the anode catalyst particles 83 to the total surface area of ​​the binder layer 82 is the same as the numerical range based on the simulation example of the cathode catalyst particles 73 described above. In addition, the method of producing the anode catalyst layer 56 and the method of controlling the exposed area of ​​the anode catalyst particles 83 are also the same as the above-mentioned method described for the cathode catalyst layer 54.

[0055] The material of the anode catalyst particles 83 includes one or more of nickel, nickel alloy, nickel oxide, copper oxide, iridium oxide, niobium oxide, lead oxide, or bismuth oxide. As described above, in this disclosure, "XX oxide" may include other materials other than XX and oxygen. For example, "nickel oxide" may include other materials such as iron and cobalt in addition to nickel and oxygen. Also, "copper oxide" may include other materials such as cobalt in addition to copper and oxygen. "iridium oxide" may include other materials such as ruthenium in addition to iridium and oxygen. "Lead oxide" may include other materials such as ruthenium in addition to lead and oxygen. "Bismuth oxide" may include other materials such as ruthenium in addition to bismuth and oxygen.

[0056] In addition, since the above-mentioned materials are used as the cathode catalyst particles 73 and the anode catalyst particles 83 (hereinafter sometimes collectively referred to as catalyst particles 91) in the above-mentioned cathode catalyst layer 54 and anode catalyst layer 56 (hereinafter collectively referred to as electrode catalyst layer 90), these materials have electronic conductivity. Therefore, the binder layers 72, 82 and the electrode catalyst layer 90 do not contain a conductive assistant for supplementing electronic conductivity.

[0057] 3 is an exploded perspective view showing the electrolysis cell 11. In addition to the components described above, the electrolysis cell 11 includes, for example, a first current collector 61, a second current collector 62, a first insulator 63, a second insulator 64, a first insulating material 65, a second insulating material 66, a first end plate 67, and a second end plate 68.

[0058] (First current collector) The first current collector 61 is an electrical connection part that transmits a negative voltage applied from the power supply unit 30 to the first separator 41. The first current collector 61 is a metal plate member (e.g., a copper plate). The first current collector 61 contacts the first separator 41 from the side opposite to the internal space S of the electrolysis cell 11, for example, and is electrically connected to the first separator 41. A negative voltage required for electrolysis in the electrolysis cell 11 is applied to the first current collector 61 from the power supply unit 30. The first current collector 61 may be shared by two electrolysis cells 11 adjacent to each other in the electrolysis cell stack 10.

[0059] (Second current collector) The second current collector 62 is an electrical connection part that transmits the positive voltage applied from the power supply unit 30 to the second separator 42. The second current collector 62 is a metal plate member (e.g., a copper plate). The second current collector 62 contacts the second separator 42, for example, from the side opposite to the internal space S of the electrolytic cell 11, and is electrically connected to the second separator 42. A positive voltage required for electrolysis in the electrolytic cell 11 is applied to the second current collector 62 from the power supply unit 30. The second current collector 62 may be shared by two electrolytic cells 11 adjacent to each other in the electrolytic cell stack 10.

[0060] (First insulator) The first insulator 63 is a member that provides insulation between the outer periphery of the first separator 41 and the outer periphery of the second separator 42. The first insulator 63 is attached to the first inner surface 41a of the first separator 41, and covers an end of the first inner surface 41a. The material of the first insulator 63 is not particularly limited as long as it is an insulating material, and is, for example, a sheet-like resin such as PTFE (polytetrafluoroethylene).

[0061] (Second insulator) The second insulator 64, like the first insulator 63, is a member that insulates between the outer periphery of the first separator 41 and the outer periphery of the second separator 42. The second insulator 64 is attached to the second inner surface 42a of the second separator 42 and covers an end of the second inner surface 42a. The material of the second insulator 64 is not particularly limited as long as it is an insulating material, and is, for example, a sheet-shaped resin such as PTFE. The first insulator 63 and the second insulator 64 can also be used as an integrated insulator.

[0062] (First insulating material) The first insulating material 65 is located between the first current collector 61 and the first end plate 67. The outer size of the first insulating material 65 is, for example, the same as or larger than the outer size of the first current collector 61.

[0063] (Second insulating material) The second insulator 66 is located between the second current collector 62 and the second end plate 68. The outer size of the second insulator 66 is, for example, the same as or larger than the outer size of the second current collector 62.

[0064] (First end plate) The first end plate 67 is located on the opposite side to the first insulating material 65 with respect to the internal space S of the electrolysis cell 11. The outer size of the first end plate 67 is larger than the outer size of the first insulating material 65, for example.

[0065] (Second end plate) The second end plate 68 is located on the opposite side to the second insulating material 66 with respect to the internal space S of the electrolysis cell 11. The outer size of the second end plate 68 is larger than the outer size of the second insulating material 66, for example.

[0066] The electrolysis cell 11 is not limited to the above-mentioned configuration. For example, when a plurality of electrolysis cells 11 are arranged side by side in the electrolysis cell stack 10, two adjacent electrolysis cells 11 among the plurality of electrolysis cells 11 may share the first separator 41 or the second separator 42, which is a bipolar plate. In this case, there may be no current collector (first current collector 61 or second current collector 62), no insulator (first insulator 63 or second insulator 64), no insulating material (first insulating material 65 or second insulating material 66), and no end plate (first end plate 67 or second end plate 68) between the two adjacent electrolysis cells 11.

[0067] (Action and effect) Here, in manufacturing an electrolysis cell, a method has been proposed in which a layer (barrier layer) for protecting a catalytic material such as platinum is provided on the surface of a solid current supplier that is not a fibrous material. The barrier layer is formed of a polymer binder and a conductive ceramic material, etc. This is to prevent early corrosion of the current supplier during the progress of the electrolysis reaction. However, when corrosion resistance is prioritized in this way, there is a problem that the contact area between the catalytic material and the electrolyte is reduced by the amount of the barrier layer provided, making it difficult to obtain the desired electrolysis performance. In order to solve this problem, the above-mentioned configurations are adopted in this embodiment.

[0068] According to the above configuration, at least a part of the catalyst particles 91 protrudes from the surface of the binder layers 72, 82. Therefore, the surface area of ​​the exposed part of the catalyst particles 91 is increased, and the contact area with the electrolyte can be increased. This makes it possible to improve the electrolysis performance from the beginning to the end of the reaction. In particular, since the catalyst particles 91 are fixed to each fiber of the power feeder via the binder layers 72, 82, the electrolyte can penetrate between the fibers, and the electrolysis reaction can be further stably and efficiently advanced. In this way, the performance of each electrolysis cell 11 is improved, and therefore the number of electrolysis cells 11 required for the same amount of hydrogen production can be reduced. As a result, the size of the entire electrolysis device 1 can be reduced, and energy saving of the plant can be achieved.

[0069] According to the above configuration, the surface area of ​​the protruding portion of the catalyst particles 91 is set to 20% or more and 80% or less of the total surface area of ​​the binder layers 72, 82. This makes it possible to improve the electrolysis performance while maintaining the retention force of the catalyst particles 91 as the binder layers 72, 82. On the other hand, if the surface area of ​​the catalyst particles 91 exposed from the binder layers 72, 82 is small, the catalyst particles 91 cannot come into contact with ions through the electrolytic solution, which may result in a decrease in electrolysis performance. According to the above configuration, such a possibility can be significantly reduced. In addition, since the surface area of ​​the binder layers 72, 82 themselves is sufficiently secured, it is possible to extend the retention force of the catalyst particles 91, that is, the lifespan. This makes it possible to continue to operate the electrolysis cell 11 stably for a longer period of time.

[0070] According to the above configuration, since the catalyst particles 91 have electronic conductivity, it is not necessary to supplement the conductivity with the binder layers 72, 82 and the electrode catalyst layer 90. Therefore, good electrolysis performance can be obtained without including a conductive assistant in the binder layers 72, 82 and the electrode catalyst layer 90 as a whole. Therefore, it is possible to reduce the manufacturing cost and maintenance cost of the device by the amount that the conductive assistant can be omitted. As a result, it is possible to reduce the supply price of hydrogen, which is the final product generated by the electrolysis reaction.

[0071] Here, while aiming to improve the electrolysis performance of the electrolysis cell 11, there is also an increasing demand for a longer life of the electrode catalyst layer 90 from the viewpoint of ensuring operability. Therefore, in this embodiment, a fluorine-based resin material is used for the binder layers 72, 82. It is known that a resin material containing fluorine has a higher adhesive force (bonding force) between objects than other substances. According to the above configuration, since a resin material containing fluorine is used for the binder layers 72, 82, it is possible to maintain a state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82. This makes it possible to avoid deterioration of the electrolysis cell 11 and realize a longer life. That is, the electrolysis cell 11 can be used stably for a long period of time without replacement or the like. This makes it possible to significantly reduce the operating costs of the device as a whole.

[0072] Among the resin materials containing fluorine, polyvinylidene fluoride is known to have a particularly high adhesive force (bonding force) between objects compared to other fluorine-based resins. According to the above configuration, since a resin material containing fluorine is used as the binder layers 72, 82, it is possible to maintain the state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82. In particular, in an environment in which the electrolyte is alkaline, the adhesive force of polyvinylidene fluoride is maintained at a higher level, which is more advantageous than other substances. This prevents deterioration of the electrolytic cell 11 and realizes a long life. That is, the electrolytic cell 11 can be used stably for a long period of time without replacement or the like. This makes it possible to significantly reduce the operating costs of the device as a whole.

[0073] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0074] For example, the materials of the cathode power supply 71 and the anode power supply 81 described in the above embodiment are merely examples, and any material that is not attacked by hydrogen or oxygen and promotes an oxidation-reduction reaction with the electrolyte can be used as the cathode power supply 71 or the anode power supply 81.

[0075] In the above embodiment, the two ion exchange membranes 120 are bonded together, but the form of the ion exchange membrane 120 is not limited to this. As another example, it is also possible to adopt a configuration in which a catalyst layer and a power supply are provided on both sides of one ion exchange membrane 120.

[0076] <Additional Notes> The electrolytic cell and the electrolytic device described in each embodiment can be understood, for example, as follows.

[0077] (1) An electrolytic cell according to a first aspect includes an ion exchange membrane, a current collector formed of a plurality of fibers formed into a sheet and disposed on a surface of the ion exchange membrane, a binder layer covering a surface of each of the fibers, and an electrode catalyst layer including catalyst particles at least a portion of which protrudes from a surface of the binder layer.

[0078] According to the above configuration, at least a portion of the catalyst particles 91 protrudes from the surfaces of the binder layers 72, 82. This increases the surface area of ​​the exposed portions of the catalyst particles 91, thereby increasing the contact area with the electrolyte.

[0079] (2) The electrolytic cell of the second aspect is the electrolytic cell of (1), wherein the surface area of ​​the portion of the catalyst particle protruding from the surface of the binder layer is 20% or more and 80% or less of the total surface area including the protruding portion and the remaining portion of the binder layer.

[0080] According to the above configuration, the surface area of ​​the protruding portions of the catalyst particles 91 is 20% or more and 80% or less of the total surface area of ​​the binder layers 72, 82. This makes it possible to improve electrolysis performance while maintaining the retention force of the binder layers 72, 82 for the catalyst particles 91.

[0081] (3) The electrolytic cell according to a third aspect is the electrolytic cell of (1) or (2), wherein the catalyst particles have electronic conductivity, and the binder layer and the electrode catalyst layer do not contain a conductive assistant.

[0082] According to the above configuration, since the catalyst particles 91 have electronic conductivity, it is not necessary to supplement the conductivity with the binder layers 72, 82 and the electrode catalyst layer 90. Therefore, good electrolysis performance can be obtained without including a conductive assistant in the binder layers 72, 82 and the electrode catalyst layer 90 as a whole.

[0083] (4) The electrolytic cell according to a fourth aspect is the electrolytic cell according to any one of (1) to (3), wherein the binder layer is formed of a resin material containing fluorine.

[0084] Here, while aiming to improve the electrolysis performance of the electrolysis cell 11, there is also an increasing demand for a longer life of the electrode catalyst layer 90 from the viewpoint of ensuring operability. Therefore, in this embodiment, a fluorine-based resin material is used for the binder layers 72, 82. It is known that a resin material containing fluorine has a higher adhesive force (bonding force) between objects than other substances. According to the above configuration, since a resin material containing fluorine is used for the binder layers 72, 82, it is possible to maintain a state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82.

[0085] (5) The electrolytic cell according to a fifth aspect is the electrolytic cell according to (4), wherein the binder layer is formed of polyvinylidene fluoride.

[0086] Among the resin materials containing fluorine, polyvinylidene fluoride is known to have a particularly high adhesive force (bonding force) between objects compared to other fluorine-based resins. According to the above configuration, since a resin material containing fluorine is used as the binder layers 72, 82, it is possible to maintain the state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82. In particular, in an environment in which the electrolyte is alkaline, the adhesive force of polyvinylidene fluoride is maintained at an even higher level, which is more advantageous than other substances.

[0087] (6) An electrolytic cell according to a sixth aspect includes an ion exchange membrane, a power supply body formed on a surface of the ion exchange membrane and consisting of a plurality of fibers formed into a sheet shape, a binder layer covering a surface of each of the fibers, and an electrode catalyst layer including catalyst particles at least a portion of which protrudes from the surface of the binder layer, and the binder layer is formed from a resin material containing fluorine.

[0088] Here, while aiming to improve the electrolysis performance of the electrolysis cell 11, there is also an increasing demand for a longer life of the electrode catalyst layer 90 from the viewpoint of ensuring operability. Therefore, in this embodiment, a fluorine-based resin material is used for the binder layers 72, 82. It is known that a resin material containing fluorine has a higher adhesive force (bonding force) between objects than other substances. According to the above configuration, since a resin material containing fluorine is used for the binder layers 72, 82, it is possible to maintain a state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82.

[0089] (7) The electrolytic cell according to a seventh aspect is the electrolytic cell according to (6), wherein the binder layer is formed of polyvinylidene fluoride.

[0090] Among the resin materials containing fluorine, polyvinylidene fluoride is known to have a particularly high adhesive force (bonding force) between objects compared to other fluorine-based resins. According to the above configuration, since a resin material containing fluorine is used as the binder layers 72, 82, it is possible to maintain the state in which the power feeder and the catalyst particles 91 are strongly bonded to each other by the binder layers 72, 82. In particular, in an environment in which the electrolyte is alkaline, the adhesive force of polyvinylidene fluoride is maintained at an even higher level, which is more advantageous than other substances.

[0091] (8) An electrolytic cell according to an eighth aspect includes an electrolytic cell according to any one of aspects (1) to (7), an electrolyte supply unit that supplies an electrolyte to the electrolytic cell, and a power supply unit that applies a voltage to the electrolytic cell.

[0092] According to the above configuration, it is possible to provide an electrolysis device having even higher electrolysis performance. [Explanation of symbols]

[0093] 1...Electrolyzer 10…Electrolysis cell stack 11, 11A, 11B...Electrolytic cell 20...Electrolyte supply section 30...Power supply section 40...Electrolytic cell 41…First separator 42…Second separator 47...Cathode 48...Anode 51...First ion exchange membrane 51a…First page 51b…Second side 52...Second ion exchange membrane 52a...Third side 52b…4th side 53...Ionomer layer 54…Cathode catalyst layer 55...Cathode power supply 56...Anode catalyst layer 57...Anode power supply 71...Cathode power supply 72...Binder layer 73…Cathode catalyst particles 81…Anode power donor 82…バインダlayer 83…Anode catalyst particles 90…Electrode catalyst layer 91…catalyst particles

Claims

1. An ion exchange membrane; a current collector formed of a plurality of fibers formed in a sheet shape and provided on a surface of the ion exchange membrane; a binder layer covering a surface of each of the fibers; an electrode catalyst layer including catalyst particles at least a part of which protrudes from a surface of the binder layer; Equipped with The electrolytic cell, wherein the catalyst particles have electronic conductivity, and the binder layer and the electrode catalyst layer do not contain a conductive assistant.

2. The electrolytic cell according to claim 1 , wherein the binder layer is formed of a resin material containing fluorine.

3. An ion exchange membrane; a current collector formed of a plurality of fibers formed in a sheet shape and provided on a surface of the ion exchange membrane; a binder layer covering a surface of each of the fibers; an electrode catalyst layer including catalyst particles at least a part of which protrudes from a surface of the binder layer; Equipped with the binder layer is formed of a resin material containing fluorine, The electrolytic cell, wherein the binder layer is formed of polyvinylidene fluoride.

4. 4. The electrolytic cell according to claim 2, wherein the binder layer is formed of polyvinylidene fluoride.

5. 4. The electrolytic cell according to claim 1, wherein a surface area of ​​a portion of the catalyst particle protruding from the surface of the binder layer is 20% or more and 80% or less of a total surface area including the protruding portion and the remaining portion of the binder layer.

6. An ion exchange membrane; a power supply body formed of a plurality of fibers formed into a sheet shape and provided on the surface of the ion exchange membrane; a binder layer covering a surface of each of the fibers; an electrode catalyst layer including catalyst particles at least a part of which protrudes from a surface of the binder layer; Equipped with the binder layer is formed of a resin material containing fluorine, The electrolytic cell, wherein the binder layer is formed of polyvinylidene fluoride.

7. The electrolytic cell according to claim 1 or 2; an electrolyte supply unit for supplying an electrolyte to the electrolytic cell; A power supply unit that applies a voltage to the electrolytic cell; An electrolysis device comprising:

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