Method for manufacturing electrodes, method for manufacturing membrane electrode structures, and method for inspecting electrodes

Abstract

The present invention provides a method for manufacturing electrodes in which, when an inspection is performed by irradiating the electrode catalyst layer with radiation such as X-rays, the detachment of light elements from the constituent elements of the ionomer resin contained in the electrode catalyst layer due to radiation irradiation is suppressed. [Solution] A method for manufacturing an electrode for a membrane electrode structure comprises a protective layer formation step and an analysis step. In the protective layer formation step, a protective layer 23 is provided on an electrode catalyst layer 22 provided on one end face of a gas diffusion layer 21. In the analysis step, radiation L is incident on the electrode catalyst layer through the protective layer. The protective layer reduces the amount of radiation L incident on the electrode catalyst layer. In this state, an analysis of the elements in the electrode catalyst layer is performed.

Description

【Technical Field】 【0001】 The present disclosure relates to a method for manufacturing an electrode, a method for manufacturing a membrane electrode assembly, and a method for inspecting an electrode. 【Background Art】 【0002】 An electrochemical device such as a fuel cell or a water electrolysis device includes a membrane electrode assembly. The membrane electrode assembly is a structure in which an anode electrode is provided on one end face of an electrolyte membrane and a cathode electrode is formed on the other end face of the electrolyte membrane. Each of the anode electrode and the cathode electrode has a gas diffusion layer and an electrode catalyst layer. The electrode catalyst layer includes an electrode catalyst and a conductive binder. 【0003】 Regarding the anode electrode and the cathode electrode configured as described above, for example, it is required to inspect whether a metal (such as platinum) as an electrode catalyst is contained in the electrode catalyst layer in a predetermined amount, or whether impurities are contained in the electrode catalyst layer. Therefore, as described in Japanese Patent Application Laid-Open No. 2018-98096, it is conceivable to perform fluorescent X-ray analysis. Note that the inspection target in the technique described in Japanese Patent Application Laid-Open No. 2018-98096 is an electrode for a secondary battery. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2018-98096 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 When fluorescent X-rays are irradiated to the electrode catalyst layer for inspection according to the description of Japanese Patent Application Laid-Open No. 2018-98096, light elements in the constituent elements of the ionomer resin contained as a conductive binder in the electrode catalyst layer may be detached. 【0006】 An object of the present disclosure is to solve the above-described problems. [Means for solving the problem] 【0007】 A first aspect of this disclosure is a method for manufacturing an electrode for a membrane electrode structure comprising a gas diffusion layer and an electrode catalyst layer which is a reaction field for gas diffused from the gas diffusion layer, the method comprising: an electrode catalyst layer forming step of providing the electrode catalyst layer, which includes an electrode catalyst and an ionomer resin, on one end face of the gas diffusion layer; a protective layer forming step of providing a protective layer, which includes the ionomer resin, on the electrode catalyst layer; and an analysis step of irradiating the electrode catalyst layer with radiation through the protective layer and analyzing the elements in the electrode catalyst layer, wherein the amount of radiation incident on the electrode catalyst layer is reduced by the protective layer compared to the amount of radiation incident on the protective layer. 【0008】 A second aspect of the present disclosure is a method for manufacturing a membrane electrode structure comprising an electrode having a gas diffusion layer and an electrode catalyst layer which is a reaction field for gas diffused from the gas diffusion layer, and an electrolyte membrane on which the electrode is provided at one end face, the method comprising: an electrode catalyst layer forming step of providing the electrode catalyst layer, which includes an electrode catalyst and an ionomer resin, at one end face of the gas diffusion layer; a protective layer forming step of providing a protective layer, which includes the ionomer resin, on the electrode catalyst layer; an analysis step of irradiating the electrode catalyst layer with radiation through the protective layer to the electrode catalyst layer obtained through the electrode catalyst layer forming step and the protective layer forming step, and analyzing the elements in the electrode catalyst layer while the amount of radiation incident on the electrode catalyst layer is reduced by the protective layer compared to the amount of radiation incident on the protective layer; and a bonding step of bonding the electrode obtained through the analysis step to one end face of the electrolyte membrane. 【0009】 A third aspect of the present disclosure is an electrode inspection method for inspecting an electrode for a membrane electrode structure comprising a gas diffusion layer and an electrode catalyst layer provided on one end face of the gas diffusion layer and containing an electrode catalyst and an ionomer resin, wherein the electrode comprises a protective layer provided on the electrode catalyst layer and containing the ionomer resin, and the method includes an analysis step of irradiating the electrode catalyst layer with radiation through the protective layer and analyzing the elements in the electrode catalyst layer, wherein the protective layer reduces the amount of radiation incident on the electrode catalyst layer compared to the amount of radiation incident on the protective layer. [Effects of the Invention] 【0010】 According to this disclosure, the detachment of light elements from the constituent elements of the ionomer resin contained in the electrode catalyst layer due to radiation irradiation is suppressed. [Brief explanation of the drawing] 【0011】 [Figure 1] Figure 1 is a schematic cross-sectional view showing a membrane electrode structure cut along the stacking direction. [Figure 2] Figure 2 is a schematic diagram of a bonding assembly manufacturing apparatus, including an anode electrode manufacturing apparatus, which constitutes an electrode manufacturing apparatus. [Figure 3] Figure 3 is a schematic diagram of the cathode electrode manufacturing apparatus, which is part of the electrode manufacturing apparatus. [Figure 4] Figure 4 shows a schematic flow chart of the manufacturing method for the membrane electrode structure. [Figure 5] Figure 5 is a schematic diagram showing the situation in which the analysis process is carried out using an analytical instrument. [Modes for carrying out the invention] 【0012】 First, the membrane electrode structure 10 will be described with reference to Figure 1. As shown in Figure 1, the membrane electrode structure 10 comprises an electrolyte membrane 12, an anode electrode 20, and a cathode electrode 25. The anode electrode 20 and the cathode electrode 25 are electrodes for the membrane electrode structure 10. 【0013】 The anode electrode 20 has a first gas diffusion layer 21 and a first electrode catalyst layer 22. The cathode electrode 25 has a second gas diffusion layer 26 and a second electrode catalyst layer 27. The first electrode catalyst layer 22 and the second electrode catalyst layer 27 face each other with the electrolyte membrane 12 in between. The membrane electrode structure 10 constitutes, for example, a single cell of a fuel cell. Alternatively, the membrane electrode structure 10 constitutes a single cell of an electrochemical decomposition device such as a water electrolysis device. 【0014】 The first gas diffusion layer 21 is a porous layer through which the gas supplied to the first gas diffusion layer 21 diffuses. Examples of gas supplied to the first gas diffusion layer 21 include hydrogen gas. Similarly, the second gas diffusion layer 26 is a layer through which the gas supplied to the second gas diffusion layer 26 diffuses. Examples of gas supplied to the second gas diffusion layer 26 include oxygen-containing gases such as compressed air. In some water electrolysis devices, oxygen-containing gas is supplied to the first gas diffusion layer 21 and hydrogen gas is supplied to the second gas diffusion layer 26. 【0015】 When the membrane electrode structure 10 is used in a fuel cell, carbon paper is an example of the material for the first gas diffusion layer 21 and the second gas diffusion layer 26. When the membrane electrode structure 10 is used in an electrochemical decomposition apparatus, a porous sintered nickel-based alloy is an example of the material for the first gas diffusion layer 21 and the second gas diffusion layer 26. In the latter case, the material for the first gas diffusion layer 21 may be a porous sintered nickel-based alloy, and the material for the second gas diffusion layer 26 may be carbon paper. 【0016】 The first electrode catalyst layer 22 includes an electrode catalyst 30 and an ionomer resin 35 as a conductive binder. The electrode catalyst 30 is composed of catalyst particles 32 supported on a conductive support 31, for example. An example of the conductive support 31 is carbon. An example of the catalyst particles 32 is a precious metal such as platinum or palladium. The ionomer resin 35 (conductive binder) functions as a binder that can hold the catalyst particles 32 and adheres well to the first gas diffusion layer 21 and the electrolyte membrane 12. The type of ionomer resin 35 varies depending on the application of the membrane electrode structure 10. For example, when the membrane electrode structure 10 is used in a fuel cell, a specific example of the ionomer resin 35 is a perfluorocarbon resin having sulfonic acid groups. When the membrane electrode structure 10 is used in an electrochemical decomposition device, a specific example of the ionomer resin 35 is a perfluorocarbon resin having sulfonic acid groups or a polymer resin having quaternary ammonium groups. 【0017】 The gas supplied to the anode electrode 20 passes through the first gas diffusion layer 21 and then reaches the first electrode catalyst layer 22, where it participates in the electrode reaction. In other words, the first electrode catalyst layer 22 is the reaction field for the gas. The catalyst particles 32 promote the electrode reaction. 【0018】 The second electrode catalyst layer 27 is configured in the same way as the first electrode catalyst layer 22. The gas supplied to the cathode electrode 25 passes through the second gas diffusion layer 26 and then participates in the electrode reaction using the second electrode catalyst layer 27 as the reaction field. 【0019】 The anode electrode 20 and the cathode electrode 25 each have a first protective layer 23 (protective layer) and a second protective layer 28 (protective layer). The first protective layer 23 contains the same type of ionomer resin 35 as the ionomer resin 35 contained in the first electrode catalyst layer 22. For example, when the ionomer resin 35 contained in the first electrode catalyst layer 22 is a perfluorocarbon resin having a sulfonic acid group, the ionomer resin 35 contained in the first protective layer 23 is a perfluorocarbon resin having a sulfonic acid group. When the ionomer resin 35 contained in the first electrode catalyst layer 22 is a polymer resin having a quaternary ammonium group, the ionomer resin 35 contained in the first protective layer 23 is a polymer resin having a quaternary ammonium group. Similarly, the second protective layer 28 contains the same type of ionomer resin 35 as the ionomer resin 35 contained in the second electrode catalyst layer 27. 【0020】 The first protective layer 23 and the second protective layer 28 containing the ionomer resin 35 as described above absorb a part of the radiation L such as X-rays (see FIG. 5) when each of the first protective layer 23 and the second protective layer 28 is irradiated with the radiation L. In other words, the first protective layer 23 and the second protective layer 28 shield a part of the radiation L. That is, when the radiation L such as X-rays is irradiated from the first protective layer 23 or the second protective layer 28, the remaining radiation from which a part of the radiation L has been absorbed reaches the first electrode catalyst layer 22 or the second electrode catalyst layer 27. 【0021】 The thickness T2 of the first protective layer 23 shown in FIG. 1 is preferably smaller than the thickness T1 of the first electrode catalyst layer 22. Thereby, it is possible to prevent all of the radiation L from being shielded by the first protective layer 23. When the thickness T1 of the first electrode catalyst layer 22 is approximately 100 μm, the thickness T2 of the first protective layer 23 is preferably within the range of 2 μm to 20 μm. In this case, it is possible to avoid an unacceptable increase in the overvoltage in the membrane electrode structure 10 compared to the overvoltage in the membrane electrode structure having no protective layer. 【0022】 A gasket (not shown) is attached to the outer circumference of the membrane electrode structure 10 configured as described above. That is, the membrane electrode structure 10, with the gasket attached, is incorporated into a fuel cell or electrochemical decomposition device. 【0023】 Next, with reference to Figures 2 and 3, a structural manufacturing apparatus 50 for producing the membrane electrode structure 10 will be briefly described. The structural manufacturing apparatus 50 comprises a bonded body manufacturing apparatus 90 shown in Figure 2 and a cathode electrode manufacturing apparatus 104 shown in Figure 3. 【0024】 As shown in Figure 2, the joint manufacturing apparatus 90 comprises a drawer section 52a, a first coating section 54a, a second coating section 56a, an inspection section 58a, a joining section 60, and a trimming section 62a. The first coating section 54a, the second coating section 56a, and the inspection section 58a also serve as the anode electrode manufacturing apparatus 102, which constitutes the electrode manufacturing apparatus 100. That is, the anode electrode manufacturing apparatus 102 constitutes part of the structure manufacturing apparatus 50 and part of the joint manufacturing apparatus 90. The anode electrode manufacturing apparatus 102 further comprises a conveyor (not shown) extending from the drawer section 52a to the trimming section 62a. 【0025】 The drawer section 52a holds the roll body 21R of the first gas diffusion layer 21. The material of the first gas diffusion layer 21 is, for example, a porous sintered nickel-based alloy. The drawer roller 521 of the drawer section 52a draws out the strip-shaped material 21S from the roll body 21R. The conveyor transports the strip-shaped material 21S. 【0026】 The first coating section 54a has a first coating machine 541 and a first dryer 545. The second coating section 56a has a second coating machine 561 and a second dryer 565. Each of the first coating machine 541 and the second coating machine 561 is a known coater, such as a spray coater, die coater, or blade coater. Each of the first dryer 545 and the second dryer 565 is, for example, a heating furnace. Alternatively, each of the first dryer 545 and the second dryer 565 may be a hot air blower. 【0027】 The inspection unit 58a has an analytical device 70a capable of irradiating with radiation L. A preferred specific example of the analytical device 70a is a fluorescent X-ray analyzer 71. However, the analytical device 70a may be a device capable of irradiating with alpha rays, beta rays, or gamma rays, etc. As shown in Figure 2, the analytical device 70a has an inspection box 701 and an irradiator 702 for irradiating with radiation L. 【0028】 The joint 60 has, for example, a hot press device 601. The trimming section 62a has a trimming machine 621. 【0029】 The cathode electrode manufacturing apparatus 104 shown in Figure 3, together with the anode electrode manufacturing apparatus 102, constitutes the electrode manufacturing apparatus 100. The cathode electrode manufacturing apparatus 104 is configured similarly to the anode electrode manufacturing apparatus 102, except that it does not have the joint portion 60 shown in Figure 2. That is, the cathode electrode manufacturing apparatus 104 includes a drawing section 52b, a first coating section 54b, a second coating section 56b, an inspection section 58b, and a trimming section 62b. The cathode electrode manufacturing apparatus 104 further includes a conveying conveyor (not shown) for transporting the strip-shaped material 26S. 【0030】 The draw-out section 52b holds the roll body 26R of the second gas diffusion layer 26. The material of the second gas diffusion layer 26 is, for example, carbon paper. The draw-out section 52b has a draw-out roller 522 for drawing out the strip material 26S from the roll body 26R. 【0031】 The first coating section 54b has a first coating machine 542 and a first dryer 546. The second coating section 56b has a second coating machine 562 and a second dryer 566. The inspection section 58b has an analytical device 70b (e.g., an X-ray fluorescence analyzer 71) capable of irradiating with radiation L. The trimming section 62b has a trimming machine 622. 【0032】 Next, the manufacturing method of the membrane electrode structure 10 according to this embodiment will be explained in relation to the electrode manufacturing method and the electrode inspection method. In the following, "coating liquid" includes slurries with relatively high viscosity. Also, "coating" means supplying the coating liquid to the object to which the coating liquid is supplied. Therefore, "coating" includes "spraying". 【0033】 Figure 4 shows a schematic flow of the manufacturing method for the membrane electrode structure 10. This manufacturing method includes the process of creating a junction 40 (see Figure 2) of the anode electrode 20 and the electrolyte membrane 12, and the process of creating the cathode electrode 25. The process up to obtaining the anode electrode 20 includes the electrode manufacturing method according to this embodiment. Similarly, the process up to obtaining the cathode electrode 25 also includes the electrode manufacturing method according to this embodiment. 【0034】 The process for manufacturing the bonded body 40 includes an electrode catalyst layer formation step S1a, a protective layer formation step S2a, an analysis step S3a, and a bonding step S4. In this embodiment, an example is given in which a trimming step S5a is performed after the bonding step S4. In the analysis step S3a, the electrode inspection method according to this embodiment is performed. 【0035】 To manufacture the anode electrode 20, first, as shown in Figure 2, a strip-shaped material 21S is drawn out from the roll body 21R by a drawing roller 521. The strip-shaped material 21S is then transported to the first coating section 54a by a conveyor belt. In the first coating section 54a, the electrode catalyst layer formation process S1a is carried out. Specifically, a coating liquid A1, which will become the first electrode catalyst layer 22, is supplied from the first coating machine 541 to one end face of the strip-shaped material 21S. The coating liquid A1 contains the electrode catalyst 30 and ionomer resin 35 shown in Figure 1. The coating liquid A1 is dried by heating in the first dryer 545. That is, the first drying process shown in Figure 4 is carried out. As a result, a first electrode catalyst layer 22 with a substantially uniform thickness T1 is obtained. 【0036】 In the strip-shaped material 21S (see Figure 2), the portion on which the first electrode catalyst layer 22 is formed is transported to the second coating section 56a by a conveyor belt. In the second coating section 56a, a protective layer formation process S2a is carried out. Specifically, a coating liquid A2, which will become the first protective layer 23, is supplied from the second coating machine 561 onto the first electrode catalyst layer 22 formed on the strip-shaped material 21S. The coating liquid A2 contains an ionomer resin 35 that can absorb (shield) a portion of the radiation L. The coating liquid A2 is dried by heating in the second dryer 565. That is, the second drying process shown in Figure 4 is carried out. As a result, a first protective layer 23 with a substantially uniform thickness T2 is obtained. 【0037】 Furthermore, by adjusting the supply amount of coating liquid A2 in the second coating machine 561, the thickness T2 of the first protective layer 23 can be made smaller than the thickness T1 of the first electrode catalyst layer 22. By adjusting the supply amount of coating liquid A2 in the second coating machine 561, it is also possible to obtain a first protective layer 23 with a thickness T2 of 2 μm to 20 μm. 【0038】 As described above, a strip-shaped first electrode portion 20p is obtained in which a first electrode catalyst layer 22 and a first protective layer 23 are laminated on a first gas diffusion layer 21, which is in the form of a strip-shaped material 21S. The first electrode portion 20p is transported to the inspection section 58a by a conveyor belt. The analysis apparatus 70a located in the inspection section 58a has an inspection box 701 and an irradiation unit 702. The first electrode portion 20p is brought inside the inspection box 701. In this state, the analysis process S3a is carried out. In other words, the electrode inspection method is performed. 【0039】 As shown in Figure 5, the irradiation device 702 irradiates the first electrode portion 20p with radiation L inside the inspection box 701. The ionomer resin 35 contained in the first protective layer 23 absorbs a portion of the radiation L incident on the first protective layer 23. Therefore, the amount of radiation L that penetrates the first protective layer 23 and enters the first electrode catalyst layer 22 is lower than the amount of radiation L incident on the first protective layer 23. In this way, when radiation L such as X-rays is irradiated from the first protective layer 23 side, the amount of radiation that reaches the first electrode catalyst layer 22 is lower than the amount of radiation L incident on the first protective layer 23. Consequently, the degree of attack of the light elements of the ionomer resin 35 contained in the first electrode catalyst layer 22 by radiation L is weakened. 【0040】 For the reasons stated above, the detachment of light elements from the ionomer resin 35 from the conductive binder is avoided. In this way, by providing a first protective layer 23 on the first electrode catalyst layer 22 and injecting radiation L into the first electrode catalyst layer 22 through the first protective layer 23, the deterioration of the ionomer resin 35 can be suppressed. Note that the light elements differ depending on the type of ionomer resin 35. In perfluorocarbon resins having sulfonic acid groups, the light elements are F, S, etc. In polymer resins having quaternary ammonium groups, the light elements are N, etc. 【0041】 When the analyzer 70a is an X-ray fluorescence analyzer 71, as shown in Figure 5, fluorescent X-rays Y are observed in response to X-rays (radiation L) being incident on the catalyst particles 32 of the electrode catalyst 30. Based on these fluorescent X-rays Y, the composition of the metal elements in the catalyst particles 32 can be determined. That is, the operator can easily determine whether or not a predetermined amount of electrode catalyst 30 is contained in the first electrode catalyst layer 22. Alternatively, the operator can easily determine whether or not impurities are contained in the first electrode catalyst layer 22. During analysis, appropriate corrections are made considering that the amount of radiation L incident on the first electrode catalyst layer 22 is reduced by the first protective layer 23. 【0042】 The first electrode portion 20p, which is determined to contain a predetermined amount of electrode catalyst 30 and have an impurity level below the permissible upper limit, is transported to the joint portion 60 by a conveyor belt. At the joint portion 60, the electrolyte membrane 12 is laminated on the first protective layer 23. In this state, the hot press device 601 is activated. The press rollers of the hot press device 601 press the first electrode portion 20p and the electrolyte membrane 12 while heating them. That is, the first electrode portion 20p and the electrolyte membrane 12 are subjected to thermocompression bonding. Through this thermocompression bonding, the first protective layer 23 and the electrolyte membrane 12 are joined to each other. The ionomer resin 35 contained in the first protective layer 23 functions as a binder. As a result, the first electrode portion 20p and the electrolyte membrane 12 are joined with sufficient bonding strength. In this way, the surface of the first protective layer 23 that is incident on radiation L such as X-rays is joined to the electrolyte membrane 12. 【0043】 Thus, according to this embodiment, the electrolyte membrane 12 is bonded to the first electrode portion 20p (anode electrode 20) which has been manufactured through the electrode catalyst layer formation step S1a, the protective layer formation step S2a, and the analysis step S3a, and which is determined to contain a predetermined amount of electrode catalyst 30. Therefore, the manufacture of a membrane electrode structure with an anode electrode 20 lacking sufficient electrode catalyst 30 is avoided. 【0044】 The first electrode portion 20p to which the electrolyte membrane 12 is attached is transported to the trimming section 62a by a conveyor belt. In the trimming section 62a, the trimming process S5a is performed. That is, the first electrode portion 20p and the electrolyte membrane 12 are cut by a trimming machine 621. This results in a jointed body 40 in which an anode electrode 20 having a predetermined surface area and an electrolyte membrane 12 having a predetermined surface area are joined together. A gasket (not shown) is attached to the jointed body 40. 【0045】 Thereafter, the electrode catalyst layer formation step S1a, protective layer formation step S2a, analysis step S3a, bonding step S4, and trimming step S5a are repeated in the same manner as described above. This allows the bonded body 40 to be mass-produced on an industrial scale. 【0046】 The cathode electrode 25 shown in Figure 1 is manufactured in the cathode electrode manufacturing apparatus 104 shown in Figure 3 through an electrode catalyst layer formation step S1b, a protective layer formation step S2b, and an analysis step S3b. In this embodiment, an example is given in which a trimming step S5b is performed after the analysis step S3b. 【0047】 First, as shown in Figure 3, in order to produce the cathode electrode 25, the strip material 26S is drawn out from the roll body 26R of the second gas diffusion layer 26 by the drawer roller 522 of the drawer section 52b. 【0048】 The strip-shaped material 26S is transported to the first coating section 54b by a conveyor belt. In the first coating section 54b, the electrode catalyst layer formation process S1b is carried out. Specifically, coating liquid A3 is supplied to the strip-shaped material 26S from the first coating machine 542. Coating liquid A3 may be the same liquid as coating liquid A1. By drying the coating liquid A3 in the first dryer 546, a second electrode catalyst layer 27 is formed on one end surface of the strip-shaped material 26S. 【0049】 Subsequently, a protective layer formation process S2b is carried out in the second coating section 56b. That is, coating liquid A4 is supplied onto the second electrode catalyst layer 27 from the second coating machine 562. Coating liquid A4 may be the same liquid as coating liquid A2. By drying coating liquid A4 in the second dryer 566, a second protective layer 28 is formed on the second electrode catalyst layer 27. As a result, the second electrode portion 25p is obtained. 【0050】 In the second coating section 56b, the second coating machine 562 can adjust the supply amount of coating liquid A4 to make the thickness T4 of the second protective layer 28 smaller than the thickness T3 of the second electrode catalyst layer 27. By adjusting the supply amount of coating liquid A4, the second coating machine 562 can also obtain a second protective layer 28 with a thickness T4 of 2 μm to 20 μm. 【0051】 Next, in the inspection section 58b, the analysis process S3b is performed. Specifically, radiation L is irradiated from the irradiator 712 of the analyzer 70b (for example, the X-ray fluorescence analyzer 71) to the second electrode portion 25p inside the inspection box 711. Note that the inspection box 701 of the analyzer 70a and the inspection box 711 of the analyzer 70b may be made of the same material. In this case, the irradiator 702 and the irradiator 712 are provided in one inspection box. 【0052】 Similarly, the second protective layer 28 weakens the degree of attack of radiation L on the light elements of the ionomer resin 35 contained in the second electrode catalyst layer 27 (see Figure 5). Thus, when radiation L such as X-rays is irradiated from the second protective layer 28 side, the amount of radiation reaching the second electrode catalyst layer 27 is lower than the amount of radiation L incident on the second protective layer 28. Therefore, the detachment of the light elements of the ionomer resin 35 from the ionomer resin 35 is avoided. 【0053】 Based on irradiation with radiation L, the second electrode portion 25p, which is determined to contain a predetermined amount of electrode catalyst 30 and have an impurity level below the permissible upper limit, is transported to the trimming section 62b by a conveyor belt. In the trimming section 62b, the trimming process S5b is performed. That is, the second electrode portion 25p is cut by the trimming machine 622 to obtain a cathode electrode 25 having a predetermined surface area. Thereafter, the electrode catalyst layer formation process S1b, the protective layer formation process S2b, the analysis process S3b, and the trimming process S5b are repeated in the same manner as described above. This allows for the mass production of cathode electrodes 25 on an industrial scale. 【0054】 The cathode electrode 25 and the bonding body 40 are laminated and bonded to each other in the lamination process S6 shown in Figure 4. In this bonding, the second protective layer 28 is positioned between the electrolyte membrane 12 and the second gas diffusion layer 26. As a result, the membrane electrode structure 10 shown in Figure 1 is obtained. In this way, it is possible to mass-produce the membrane electrode structure 10 on an industrial scale. The ionomer resin 35 contained in the second protective layer 28 bonds the electrolyte membrane 12 and the second protective layer 28 with sufficient bonding strength. In this way, the surface of the second protective layer 28 to which radiation L such as X-rays is incident is bonded to the electrolyte membrane 12. 【0055】 The method for manufacturing the electrodes is not limited to the method of feeding out the strip-shaped materials 21S and 26S. For example, an anode electrode 20 may be obtained by laminating a first electrode catalyst layer 22 and a first protective layer 23 onto one end face of a first gas diffusion layer 21 that has been pre-cut to a predetermined surface area. Similarly, a cathode electrode 25 may be obtained by laminating a second electrode catalyst layer 27 and a second protective layer 28 onto one end face of a second gas diffusion layer 26 that has been pre-cut to a predetermined surface area. In this case, trimming steps S5a and S5b are unnecessary. 【0056】 The membrane electrode structure 10 is used, for example, in electrochemical devices such as fuel cells or electrochemical decomposition devices. As described above, the first electrode catalyst layer 22 and the second electrode catalyst layer 27 contain a predetermined amount of electrode catalyst 30. Furthermore, the amount of impurities in the first electrode catalyst layer 22 and the second electrode catalyst layer 27 is below the permissible upper limit. Therefore, the electrode reaction proceeds smoothly in both the anode electrode 20 and the cathode electrode 25. 【0057】 As described above, the detachment of light elements from the ionomer resin 35 contained in the first electrode catalyst layer 22 is suppressed, and the detachment of light elements from the ionomer resin 35 contained in the second electrode catalyst layer 27 is also suppressed. Therefore, each ionomer resin 35 functions sufficiently as a conductive binder. In other words, the first electrode catalyst layer 22 and the second electrode catalyst layer 27 exhibit sufficient electrical conductivity and sufficient binding force. 【0058】 For the reasons stated above, fuel cells can provide sufficient power. Furthermore, electrochemical decomposition devices can improve the yield of the desired product. 【0059】 This embodiment provides the following effects. Hereinafter, when the anode electrode 20 and the cathode electrode 25 are not distinguished, they will simply be referred to as "electrodes." Similarly, when the first electrode catalyst layer 22 and the second electrode catalyst layer 27 are not distinguished, they will simply be referred to as "electrode catalyst layers," and when the first protective layer 23 and the second protective layer 28 are not distinguished, they will simply be referred to as "protective layers." 【0060】 As shown in Figure 4, the method for manufacturing an electrode for the membrane electrode structure 10 includes analysis steps S3a and S3b, which are performed after protective layer formation steps S2a and S2b, in which a protective layer (see Figure 1) is placed on the electrode catalyst layer. As shown in Figure 5, in analysis steps S3a and S3b, radiation L is irradiated onto the protective layer from the analysis apparatus 70a. A portion of the radiation L is shielded by the protective layer. Therefore, the amount of radiation L incident on the electrode catalyst layer is smaller than the amount of radiation L incident on the protective layer. 【0061】 Therefore, the detachment of light elements from the ionomer resin 35 contained in the electrode catalyst layer due to radiation L is suppressed. In other words, the alteration of the ionomer resin 35 due to irradiation with radiation L is suppressed. For this reason, when a membrane electrode structure 10 equipped with this electrode is constructed, and a fuel cell or the like is constructed using the membrane electrode structure 10, the electrode catalyst layer exhibits sufficient electrical conductivity and binding strength. That is, the ionomer resin 35 functions sufficiently as a conductive binder. 【0062】 Furthermore, the type of ionomer resin 35 contained in the electrode catalyst layer and the type of ionomer resin 35 contained in the protective layer are the same. Therefore, the material cost is lower compared to the case where the types of ionomer resin 35 contained in the electrode catalyst layer and the types of ionomer resin 35 contained in the protective layer are different. 【0063】 In protective layer formation steps S2a and S2b, coating solutions A2 and A4 containing ionomer resin 35 are supplied (coated) to the electrode catalyst layer. This allows for easy formation of a protective layer on the electrode catalyst layer. 【0064】 The protective layer formation steps S2a and S2b include a drying step to dry the coating solutions A2 and A4. Therefore, analysis of the electrode catalyst layer can be easily performed. 【0065】 In the protective layer formation steps S2a and S2b, the protective layer is formed such that its thickness T2 and T4 are smaller than the thickness T1 and T3 of the electrode catalyst layer. This prevents the protective layer from completely shielding the radiation L in the analysis steps S3a and S3b. In other words, radiation L can be incident on the electrode catalyst layer. 【0066】 Radiation L is, for example, X-rays. In this case, elemental composition analysis is straightforward. 【0067】 The manufacturing method for the membrane electrode structure 10 includes a bonding step S4 in which the electrode manufactured as described above is bonded to the electrolyte membrane 12. This makes it possible to obtain a membrane electrode structure 10 having an electrode catalyst layer that is determined to contain a predetermined amount of metal. As a result, the yield of the membrane electrode structure 10 is good. 【0068】 The electrode catalyst layer formation steps S1a and S1b are steps in which coating liquids A1 and A3, which will form the electrode catalyst layer, are supplied to one end surface of the strip-shaped material 21S and 26S of the gas diffusion layer. The protective layer formation steps S2a and S2b are steps in which coating liquids A2 and A4, which will form the protective layer, are supplied onto the electrode catalyst layer. The analysis steps S3a and S3b are steps in which radiation L is incident on the electrode catalyst layer on the strip-shaped material 21S through the protective layer. Furthermore, the trimming steps S5a and S5b are steps in which the strip-shaped material 21S and 26S, the electrode catalyst layer and the protective layer are trimmed after the analysis steps S3a and S3b. 【0069】 By going through this process, the membrane electrode structure 10 can be mass-produced on an industrial scale. 【0070】 The electrode inspection method includes analytical steps S3a and S3b, in which radiation L is irradiated onto the electrode catalyst layer through a protective layer, and elements in the electrode catalyst layer are analyzed. The protective layer reduces the amount of radiation L incident on the electrode catalyst layer compared to the amount of radiation L incident on the protective layer. 【0071】 When radiation L is incident on the electrode catalyst layer as described above, the detachment of light elements from the constituent elements of the ionomer resin 35 contained in the electrode catalyst layer is suppressed. Therefore, in the film electrode structure 10, the ionomer resin 35 in the electrode catalyst layer functions as both a conductor and a binder. 【0072】 A suitable example of a radiation irradiation device for irradiating the protective layer with radiation L is a fluorescence X-ray analyzer 71. In this case, the elemental composition of the electrode catalyst layer can be easily analyzed. 【0073】 The radiation irradiation device for irradiating the protective layer with radiation L is provided in the electrode manufacturing apparatus 100 that manufactures electrodes. Therefore, electrode manufacturing and inspection can be carried out continuously in the mass production facility. 【0074】 The following additional information is disclosed regarding the above embodiments. 【0075】 (Note 1) The present disclosure is a method for manufacturing an electrode for a membrane electrode structure (10) comprising a gas diffusion layer (21, 26) and an electrode catalyst layer (22, 27) which is a reaction field for gas diffused from the gas diffusion layer, comprising: an electrode catalyst layer formation step (S1a, S1b) in which the electrode catalyst layer, which includes an electrode catalyst (30) and an ionomer resin (35), is provided on one end face of the gas diffusion layer; a protective layer formation step (S2a, S2b) in which a protective layer (23, 28) containing the ionomer resin is provided on the electrode catalyst layer; and an analysis step (S3a, S3b) in which radiation (L) is irradiated onto the electrode catalyst layer through the protective layer and elements in the electrode catalyst layer are analyzed, wherein the protective layer reduces the amount of radiation incident on the electrode catalyst layer compared to the amount of radiation incident on the protective layer. 【0076】 In the analysis process described above, the detachment of light elements contained in the conductive binder from the ionomer resin can be suppressed. Therefore, after the analysis process, the ionomer resin functions as both a conductor and a binder. 【0077】 (Note 2) In the electrode manufacturing method described in Appendix 1, the protective layer formation step may be a step of supplying a coating solution (A2, A4) containing the ionomer resin to the electrode catalyst layer. 【0078】 This makes it easy to form a protective layer. 【0079】 (Note 3) In the electrode manufacturing method described in Appendix 2, the protective layer forming step may include a drying step of drying the coating liquid. 【0080】 Since the protective layer is a dry material, the analysis process can be easily carried out. 【0081】 (Note 4) In the electrode manufacturing method described in any one of the appendices 1 to 3, the protective layer may be formed such that the thickness of the protective layer (T2, T4) is smaller than the thickness of the electrode catalyst layer (T1, T3). 【0082】 This prevents the protective layer from completely shielding the radiation; in other words, radiation can enter the electrode catalyst layer. 【0083】 (Note 5) In the method for manufacturing electrodes described in any one of the appendices 1 to 4, X-rays may be used as the radiation. 【0084】 In this case, the elemental composition analysis of the electrode catalyst layer is straightforward. 【0085】 (Note 6) A method for manufacturing a membrane electrode structure (10) according to the present disclosure comprises electrodes (20, 25) having gas diffusion layers (21, 26) and electrode catalyst layers (22, 27) which are reaction fields for gas diffused from the gas diffusion layers, and an electrolyte membrane (12) on which the electrodes are provided at one end face, comprising: an electrode catalyst layer forming step (S1a, S1b) in which an electrode catalyst layer containing an electrode catalyst (30) and an ionomer resin (35) is provided at one end face of the gas diffusion layer, and a protective layer (23, The process includes: a protective layer formation step (S2a, S2b) for providing 28); an analysis step (S3a, S3b) for analyzing the elements in the electrode catalyst layer, performed by irradiating the electrode catalyst layer with radiation (L) through the protective layer, thereby reducing the amount of radiation incident on the electrode catalyst layer by the protective layer compared to the amount of radiation incident on the protective layer; and a bonding step (S4) for bonding the electrode that has undergone the analysis step to one end face of the electrolyte membrane. 【0086】 Since the electrode that has undergone the analysis process is bonded to the electrolyte membrane, a membrane electrode structure equipped with an electrode catalyst layer having a predetermined amount of metal can be obtained. 【0087】 (Note 7) In the method for manufacturing the membrane electrode structure described in Appendix 6, the surface of the protective layer that has been incident on the radiation in the analysis step may be bonded to the electrolyte membrane in the bonding step. 【0088】 (Note 8) In the method for manufacturing a membrane electrode structure described in Appendix 6 or 7, the protective layer may be formed such that the thickness of the protective layer (T2, T4) is smaller than the thickness of the electrode catalyst layer (T1, T3). 【0089】 As described above, the protective layer does not completely shield the radiation. In other words, radiation can enter the electrode catalyst layer. 【0090】 (Note 9) In the method for manufacturing a membrane electrode structure described in any one of appendices 6 to 8, X-rays may be used as the radiation. 【0091】 As mentioned above, the elemental composition analysis of the electrode catalyst layer is straightforward. 【0092】 (Note 10) In the method for manufacturing a membrane electrode structure as described in any one of appendices 6 to 9, the electrode catalyst layer formation step is a step of feeding out a strip-shaped material (21S, 26S) of the gas diffusion layer and supplying a coating liquid (A1, A3) containing the electrode catalyst and the ionomer resin to one end face of the strip-shaped material; the protective layer formation step is a step of supplying a coating liquid (A2, A4) containing the ionomer resin onto the electrode catalyst layer formed on one end face of the strip-shaped material; the analysis step is a step of injecting the radiation onto the electrode catalyst layer on the strip-shaped material through the protective layer; and after the analysis step, the method may further include a trimming step (S5a, S5b) for trimming the strip-shaped material, the electrode catalyst layer and the protective layer. 【0093】 This makes it possible to mass-produce membrane electrode structures equipped with tested electrodes (electrodes containing a predetermined amount of metal element in the electrode catalyst layer) on an industrial scale. 【0094】 (Note 11) The method for inspecting electrodes (20, 25) of the present disclosure is a method for inspecting electrodes for a membrane electrode structure (10) comprising a gas diffusion layer (21, 26) and an electrode catalyst layer (22, 27) provided on one end face of the gas diffusion layer and containing an electrode catalyst (30) and an ionomer resin (35), wherein the electrode comprises a protective layer (23, 28) provided on the electrode catalyst layer and containing the ionomer resin, and the method includes an analysis step (S3a, S3b) in which radiation (L) is irradiated onto the electrode catalyst layer via the protective layer and elements in the electrode catalyst layer are analyzed, wherein the protective layer reduces the amount of radiation incident on the electrode catalyst layer compared to the amount of radiation incident on the protective layer. 【0095】 This prevents light elements contained in the ionomer resin from detaching from the resin. Therefore, in the membrane electrode structure fabricated after the analysis process, the ionomer resin functions effectively as both a conductor and a binder. 【0096】 (Note 12) In the electrode inspection method described in Appendix 11, the analytical device (70a, 70b) that irradiates the protective layer with radiation may be an X-ray fluorescence analyzer (71). 【0097】 In this case, the elemental composition analysis of the electrode catalyst layer is straightforward. 【0098】 (Note 13) In the electrode inspection method described in Appendix 11 or 12, the analytical device (70a, 70b) for irradiating the protective layer with radiation may be provided in the electrode manufacturing device (100) that manufactures the electrode. 【0099】 This configuration allows for the continuous manufacturing and inspection of electrodes in a mass production facility. 【0100】 While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols] 【0101】 10...Membrane electrode structure 12...Electrolyte membrane 20... Anode (electrode) 21, 26... Gas diffusion layer 21S, 26S… Strip-shaped material; 22, 27… Electrode catalyst layer 23, 28… Protective layer 25… Cathode electrode 30... Electrode catalyst 35... Ionomer resin 50...Structural manufacturing equipment 58a, 58b...Inspection department 70a, 70b...Analytical equipment 71...Fluorescent X-ray analyzer 90…Joint manufacturing equipment 100…Electrode manufacturing equipment L...Radiation Y...Fluorescent X-rays

Claims

[Claim 1] A method for manufacturing an electrode for a membrane electrode structure comprising a gas diffusion layer and an electrode catalyst layer which is a reaction field for the gas diffused from the gas diffusion layer, An electrode catalyst layer formation step is provided on one end face of the gas diffusion layer, the electrode catalyst layer containing the electrode catalyst and ionomer resin, A protective layer formation step is provided on the electrode catalyst layer, including the protective layer containing the ionomer resin. An analytical step of irradiating the electrode catalyst layer with radiation through the protective layer and analyzing the elements in the electrode catalyst layer, It has, A method for manufacturing an electrode, wherein the amount of radiation incident on the electrode catalyst layer is reduced compared to the amount of radiation incident on the protective layer by the protective layer. [Claim 2] A method for manufacturing an electrode according to claim 1, wherein the protective layer forming step is a step of supplying a coating solution containing the ionomer resin to the electrode catalyst layer. [Claim 3] A method for manufacturing an electrode according to claim 2, wherein the protective layer forming step includes a drying step of drying the coating liquid. [Claim 4] A method for manufacturing an electrode according to claim 1, wherein the protective layer is formed such that the thickness of the protective layer is less than the thickness of the electrode catalyst layer. [Claim 5] A method for manufacturing an electrode according to any one of claims 1 to 4, wherein the electrode is irradiated with X-rays as the radiation. [Claim 6] A method for manufacturing a membrane electrode structure comprising an electrode having a gas diffusion layer, an electrode catalyst layer which is a reaction field for gas diffused from the gas diffusion layer, and an electrolyte membrane on which the electrode is provided at one end face, An electrode catalyst layer formation step is provided on one end face of the gas diffusion layer, the electrode catalyst layer containing the electrode catalyst and ionomer resin, A protective layer formation step is provided on the electrode catalyst layer, including the protective layer containing the ionomer resin. An analysis step is performed on the electrode obtained through the electrode catalyst layer formation step and the protective layer formation step, by irradiating the electrode catalyst layer with radiation through the protective layer, thereby reducing the amount of radiation incident on the electrode catalyst layer compared to the amount of radiation incident on the protective layer, and analyzing the elements in the electrode catalyst layer. A bonding step is performed to bond the electrode that has undergone the analysis step to one end face of the electrolyte membrane, A method for manufacturing a membrane electrode structure having the following characteristics. [Claim 7] A method for manufacturing a membrane electrode structure according to claim 6, wherein in the analysis step, the surface of the protective layer to which the radiation was incident is bonded to the electrolyte membrane in the bonding step. [Claim 8] A method for manufacturing a membrane electrode structure according to claim 6, wherein the protective layer is formed such that the thickness of the protective layer is less than the thickness of the electrode catalyst layer. [Claim 9] A method for manufacturing a membrane electrode structure according to claim 6, wherein the radiation is X-rays. [Claim 10] In the method for manufacturing a membrane electrode structure according to any one of claims 6 to 9, the electrode catalyst layer formation step is a step of feeding out a strip-shaped material of the gas diffusion layer and supplying a coating liquid containing the electrode catalyst and the ionomer resin to one end face of the strip-shaped material, The protective layer formation step is a step of supplying a coating liquid containing the ionomer resin onto the electrode catalyst layer formed on one end face of the strip-shaped material, The analysis step is a step of injecting the radiation onto the electrode catalyst layer on the strip-shaped material through the protective layer, A method for manufacturing a membrane electrode structure, further comprising a trimming step of trimming the strip-shaped material, the electrode catalyst layer, and the protective layer after the analysis step. [Claim 11] A method for inspecting an electrode for a membrane electrode structure comprising a gas diffusion layer and an electrode catalyst layer provided on one end face of the gas diffusion layer and containing an electrode catalyst and an ionomer resin, The electrode is provided on the electrode catalyst layer and includes a protective layer containing the ionomer resin, The analysis step involves irradiating the electrode catalyst layer with radiation through the protective layer and analyzing the elements in the electrode catalyst layer. An electrode inspection method comprising the protective layer, wherein the amount of radiation incident on the electrode catalyst layer is reduced compared to the amount of radiation incident on the protective layer. [Claim 12] A method for inspecting an electrode according to claim 11, wherein the analytical device for irradiating the protective layer with radiation is an X-ray fluorescence analyzer. [Claim 13] The electrode inspection method according to claim 11, wherein the analytical device for irradiating the protective layer with radiation is provided in an electrode manufacturing apparatus for manufacturing the electrode.

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