Proton resistance measuring device, proton resistance measuring system, and proton resistance measuring method

Abstract

To provide a measurement device capable of quantitatively measuring proton resistance in a thickness direction of an electrode layer containing an electrode material and a proton conductive electrolyte.SOLUTION: A proton resistance measurement device comprises: a detected electrode consisting of an electrode layer containing an electrode material and a proton conductive electrolyte; a first proton conduction film and a second proton conduction film holding the detected electrode in a thickness direction therebetween; a laminate for measurement consisting of a first electron conductive gas diffusion electrode and a second electron conductive gas diffusion electrode holding the first proton conduction film and the second proton conduction film, which hold the detected electrode therebetween, in the thickness direction therebetween; and a first electrode and a second electrode holding the laminate for measurement in the thickness direction therebetween. A proton resistance measurement system comprising the proton resistance measurement device and an evaluation device, which is connected to the first electrode and the second electrode and executes a current cutoff method, is used to measure proton resistance in the thickness direction of the detected electrode consisting of the electrode layer containing the electrode material and the proton conductive electrolyte in accordance with the current cutoff method.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a measuring device, a measuring system, and a measuring method for measuring the proton resistance in an electrode (electrode layer) including a proton-conductive electrolyte used in a solid polymer fuel cell or the like. 【Background Art】 【0002】 A solid polymer fuel cell (Polymer Electrolyte Fuel Cell, PEFC) is composed of a membrane electrode assembly (Membrane and Electrode Assembly, MEA) including an electrolyte membrane and electrodes (electrode catalyst layers) laminated on both sides of the electrolyte membrane, and gas diffusion layers (Gas Diffusion Layer, GDL) laminated on both sides of the membrane electrode assembly. A cell having a structure in which a power generation module is sandwiched between two separators in which gas flow paths are formed is used as a basic unit. The electrode (electrode catalyst layer) in the membrane electrode assembly is composed of an electrode material and a proton-conductive electrolyte (typically, an ionomer which is a proton conductor). Further, a thin film of a proton-conductive electrolyte (typically, a Nafion membrane) is used for the electrolyte membrane. 【0003】 Regarding a standardized measuring method for the proton conductivity of the electrolyte membrane of a PEFC, as a PEFC cell evaluation analysis protocol of the New Energy and Industrial Technology Development Organization (NEDO), a method of measuring the proton conductivity in the direction along the membrane surface (membrane plane direction) of the electrolyte membrane by an alternating current impedance method (Non-Patent Document 1) has been proposed. However, in a PEFC, since protons move from the anode provided on one side of the electrolyte membrane to the cathode provided on the opposite side, it is more important to accurately measure the proton conductivity in the membrane thickness direction (thickness direction) of the electrolyte membrane. The proton conductivity of an electrolyte membrane in the film thickness direction can be measured using a commercially available proton conductivity measuring device 100 for electrolyte membranes, for example, as shown in the conceptual diagram in Figure 10. As shown in Figure 10, in a conventional proton conductivity measuring device 100, the proton resistance of the electrolyte membrane 120 can be measured as ohmic resistance (resistance in which the current flowing and the potential difference (voltage) across its terminals change linearly according to Ohm's law) by applying alternating current to the electrolyte membrane 120 using a four-terminal method (using Pt (platinum) plates (gas impermeable) 111-114 as electrodes) under a hydrogen atmosphere. The proton conductivity of the electrolyte membrane 120 can then be calculated from the obtained proton resistance and film thickness. 【0004】 On the other hand, in PEFCs, not only the proton conductivity of the electrolyte membrane but also the proton conductivity of the electrode layer containing the proton-conducting electrolyte significantly affects the performance of the PEFC. Therefore, in order to develop high-performance PEFCs, it is necessary to measure the proton resistance of the electrode layer constituting the MEA with high precision. However, a method for directly measuring the proton conductivity within the electrode layer of a PEFC has not yet been established. 【0005】 As one of the few reported direct measurements of proton conductivity within an electrode layer, Patent Document 1 discloses an apparatus for measuring ion current and electron current to determine effective ion conductivity (proton conductivity) and effective electron conductivity. The apparatus described in Patent Document 1 comprises two potentiostats and a bias power supply. Each potentiostat has a working electrode, a reference electrode, a counter electrode, an ammeter, a voltmeter for measuring the voltage between the working electrode and the reference electrode, and a power supply for applying a voltage between the working electrode and the counter electrode according to the measured voltage value. The apparatus is used to measure electrode materials formed with ion conductors and electron conductors. The counter electrode and reference electrode are connected to the ion conductor, and the working electrode is connected to the electron conductor. The potentiostats are operated with the open-circuit potential difference of the electrode materials set to a value, and the bias power supply applies a voltage between the working electrodes. In this measurement state, the measured values ​​of the ammeters are determined as the ion current and electron current. While this measuring device allows for the simultaneous measurement of ionic and electronic conductivity of porous electrodes, it uses a six-terminal method with two potentiostats, which results in a high cost for the device. 【0006】 On the other hand, the present inventors have previously attempted to measure the proton resistance within the electrode layer of PEFCs (Non-Patent Literature 2). In this measurement method, the conventional proton conduction measuring device for electrolyte membranes described above was used, and a measurement laminate in which the electrode layer was sandwiched between two Nafion films was used to measure the proton resistance of the electrode layer consisting of electrode material and proton-conducting electrolyte. An attempt was made to block the movement of electrons within the electrode layer with the Nafion films sandwiching the electrode layer. However, the measurement method (AC impedance method) that applies an alternating current as shown in Figure 11(A) has the problem that electron movement within the electrode layer cannot be eliminated. Figure 11(A) is a conceptual diagram of the case when an alternating current is applied to a measurement laminate in which the electrode layer 140 is sandwiched between Nafion films 131 and 132. Electron movement within Nafion films 131 and 132 can be eliminated, but electron movement within the electrode layer 140 cannot. Furthermore, while the method of applying a direct current as shown in Figure 11(B) eliminates the influence of electron movement and allows for the evaluation of proton conductivity, commercially available proton conductivity measuring devices use Pt plates (gas-impermeable) as electrodes, and the structure in which the electrode (Pt plate) and the electrolyte membrane (Nafion membrane) are in direct contact limits the supply of hydrogen during measurement. This leads to a problem in that the hydrogen diffusion resistance affects the measurement, making it impossible to quantitatively evaluate the proton resistance. [Prior art documents] [Patent Documents] 【0007】 [Patent Document 1] Patent No. 5062772 [Non-patent literature] 【0008】 [Non-Patent Document 1] The New Energy and Industrial Technology Development Organization (NEDO)'s PEFC Cell Evaluation and Analysis Protocol (March 2022 edition), 3. Cell Performance Evaluation Protocol (1) Electrolyte Membrane A. Evaluation Method for the Membrane Alone M 1 (III 1 1) Test Name: Proton Conductivity Measurement Method 1 / 2 [Non-Patent Document 2] Taichi Matoba, Investigation of the correlation between proton conduction and durability in PEFC cathodes, Master's Thesis, Kyushu University Graduate School (2020) [Overview of the project] [Problems that the invention aims to solve] 【0009】 As described above, although proton conductivity within the electrode layer is one of the important factors, the reality is that methods for directly measuring it have not yet been sufficiently established. Under these circumstances, the present invention aims to provide a proton resistance measuring device, measuring system, and measuring method capable of quantitatively measuring the proton resistance in an electrode layer comprising an electrode material and a proton-conducting electrolyte. [Means for solving the problem] 【0010】 The inventors of this invention have conducted extensive research to solve the above problems and have found that the following invention is suitable for the above purpose, leading to the present invention. 【0011】 In other words, the present invention relates to the following invention. <1> A proton resistance measuring device for measuring the proton resistance in the thickness direction of an electrode under test, which consists of an electrode layer containing an electrode material and a proton-conducting electrolyte, The electrode to be tested and, A first proton-conducting film and a second proton-conducting film sandwich the electrode to be tested in the thickness direction, The first proton-conducting film and the second proton-conducting film, which sandwich the electrode under test, are sandwiched in the thickness direction by a first electron-conducting gas diffusion electrode and a second electron-conducting gas diffusion electrode, A measuring laminate consisting of, The first electrode and the second electrode sandwich the aforementioned measuring laminate in the thickness direction, A proton resistance measuring device equipped with the following features. <2> The electrode under test is composed solely of an electronically conductive material without supported electrode catalyst particles and a proton-conducting electrolyte. <1> The proton resistance measuring device described above <3> The first electrode and the second electrode have a gas channel on the side that is in close contact with the first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode. <1> or <2> The proton resistance measuring device described above. <4> The first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode each consist of a catalyst layer made of a carbon material on which Pt is supported, and a gas diffusion layer made of a carbon material. <1> from <3> A proton resistance measuring device as described in any of the following. <5> The first proton-conducting film and the second proton-conducting film are proton-conducting polymer films. <1> from <4> A proton resistance measuring device as described in any of the following. <6> <1> from <5> A proton resistance measuring device as described in any of the following, An evaluation device connected to the first and second electrodes, which performs a current interruption method, A proton resistance measurement system equipped with the following features. <7> <6> A method for measuring proton resistance, which uses the proton resistance measurement system described above to measure the proton resistance in the thickness direction of an electrode under test, comprising an electrode layer containing the electrode material and a proton-conducting electrolyte, by a current interruption method. <8> A membrane electrode assembly for use in a proton resistance measuring device for measuring the proton resistance in the thickness direction of an electrode to be tested, which consists of an electrode layer containing an electrode material and a proton-conducting electrolyte, comprising: the electrode to be tested; a first proton-conducting membrane and a second proton-conducting membrane that sandwich the electrode to be tested in the thickness direction; and a first catalyst layer and a second catalyst layer that sandwich the first proton-conducting membrane and the second proton-conducting membrane that sandwich the electrode to be tested in the thickness direction. [Effects of the Invention] 【0012】 According to the present invention, there are provided a proton resistance measuring device, a measuring system, and a measuring method capable of quantitatively measuring the proton resistance in an electrode layer including an electrode material and a proton conductive electrolyte. 【Brief Description of Drawings】 【0013】 [Figure 1] It is a cross-sectional schematic view showing an example of a proton resistance measuring device according to the present invention. [Figure 2] It is a cross-sectional schematic view showing an example of an electronically conductive gas diffusion electrode. [Figure 3] It is a diagram showing an example of a manufacturing procedure of a catalyst layer of a test electrode and an electronically conductive gas diffusion electrode. [Figure 4] It is a conceptual diagram showing the configuration of a proton resistance measuring system according to the present invention. [Figure 5] It is a circuit diagram showing an equivalent circuit of a measurement laminate. [Figure 6] It is an explanatory diagram showing an example of temporal change of voltage in a current interruption method. [Figure 7] It is an external photograph (plan view) of a fabricated membrane electrode assembly (measurement laminate (without gas diffusion layer)). [Figure 8] It is a photograph of a self folder used in an example, (a) separator flow path portion, (b) entire self folder view. [Figure 9] It is a diagram showing the configuration of a proton resistance measuring system used in an example. [Figure 10] It is a conceptual diagram showing an example of a conventional proton conduction measuring device for an electrolyte membrane. [Figure 11] It is a schematic diagram showing the movement of electrons and protons when measuring the proton resistance of an electrode using a conventional proton conduction measuring device for an electrolyte membrane ((A) during AC application, (B) during DC application). 【Embodiments for Carrying Out the Invention】 【0014】 The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and can be modified and implemented as appropriate without departing from the spirit of the invention. In this specification, "~" is used to mean an expression that includes the numerical value or physical quantity before and after it. Also, in this specification, the expression "A and / or B" includes "A only," "B only," and "both A and B." 【0015】 The proton resistance measuring device of the present invention is a proton resistance measuring device for measuring the proton resistance in the thickness direction of an electrode to be measured, which is made up of an electrode layer containing an electrode material and a proton-conducting electrolyte, and is characterized by comprising: the electrode to be measured; a measuring laminate comprising a first proton-conducting film and a second proton-conducting film that sandwich the electrode to be measured in the thickness direction; a first electron-conducting gas diffusion electrode and a second electron-conducting gas diffusion electrode that sandwich the first proton-conducting film and the second proton-conducting film that sandwich the electrode to be measured in the thickness direction; and a first electrode and a second electrode that sandwich the measuring laminate in the thickness direction. In the following, the first proton-conducting film and the second proton-conducting film may be collectively referred to as "proton-conducting film," and the first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode may be collectively referred to as "gas diffusion electrode." 【0016】 Furthermore, the proton resistance measurement system of the present invention is a system for measuring the proton resistance in the thickness direction of an electrode under test, which consists of an electrode layer containing an electrode material and a proton-conducting electrolyte, and is characterized by comprising the proton resistance measurement device of the present invention described above, and an evaluation device connected to the first electrode and the second electrode, which performs a current interruption method. 【0017】 Furthermore, the present invention provides a method for measuring the proton resistance of an electrode layer, comprising an electrode layer containing an electrode material and a proton-conducting electrolyte, and is characterized by measuring the proton resistance in the thickness direction of the electrode layer comprising the electrode material and the proton-conducting electrolyte by current interruption using the proton resistance measurement system of the present invention described above. 【0018】 With this configuration, a first electron-conducting gas diffusion electrode and a second electron-conducting gas diffusion electrode, through which hydrogen gas can pass, are provided between the first and second electrodes and the first and second proton-conducting membranes. This makes it possible to supply hydrogen more smoothly compared to using a conventional proton conduction measuring device. Furthermore, if gas channels are provided in the first and second electrodes, it becomes easier to supply hydrogen gas to the first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode from the outside. By facilitating the supply of hydrogen in this way, the effect of hydrogen diffusion resistance is suppressed, and protons are supplied smoothly to the electrode under test, which consists of an electrode layer. This makes it possible to quantitatively measure the proton resistance within the electrode layer using the current interruption method with applied DC current. 【0019】 Preferred embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In addition, in all drawings, similar components are denoted by the same reference numerals, and descriptions are omitted as appropriate. 【0020】 Figure 1 is a schematic cross-sectional view of a proton resistance measuring device 10 according to an embodiment of the present invention. As shown in Figure 1, the proton resistance measuring device 10 comprises a measuring laminate consisting of a test electrode 11, proton conductive films 12a and 12b (first proton conductive film, second proton conductive film) that sandwich the test electrode 11 in the thickness direction, and electron conductive gas diffusion electrodes 13a and 13b (first electron conductive gas diffusion electrode, second electron conductive gas diffusion electrode) that sandwich the proton conductive films 12a and 12b in the thickness direction, and electrodes 14a and 14b (first electrode, second electrode) that sandwich the measuring laminate in the thickness direction. In Figure 1, the upper surface is referred to as the top surface, the lower surface as the bottom surface, and the vertical direction is the thickness direction. 【0021】 (Test electrode) The electrode under test 11 is an electrode that simulates the electrodes (anode and cathode) of a polymer electrolyte fuel cell (PEFC) or polymer electrolyte water electrolysis device, and is the target for measuring the proton resistance in the thickness direction. In this embodiment, the electrode under test 11 consists of an electrode layer containing an electrode material and a proton-conducting electrolyte. 【0022】 The electrode material and proton-conducting electrolyte constituting the electrode 11 under test are materials used in electrodes (electrode catalyst layers) in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers (see, for example, Japanese Patent Publication No. 6598159 and Japanese Patent Publication No. 6779470). 【0023】 The electrode 11 to be tested according to this embodiment consists of an electrode layer comprising an "electron-conductive material without supported electrode catalyst particles" (electrode material) and a "proton-conducting electrolyte". The electrode material constituting the electrode layer of the electrode under test 11 can be any material that has electronic conductivity, such as carbon materials or electronically conductive oxide materials, but typically it is a carbon material. In addition, while polymer electrolyte fuel cells or polymer electrolyte water electrolyzers typically use an electron-conductive material (typically a carbon material) as the electrode material, on which electrode catalyst nanoparticles (typically noble metal nanoparticles such as Pt) are highly dispersed, it is preferable that the electrode material constituting the electrode 11 does not have electrode catalyst nanoparticles supported on it, in order to measure the proton resistance of the electrode 11 with higher precision. 【0024】 As the proton-conducting electrolyte contained in the electrode layer of the electrode 11 under test, known fluorine-based electrolyte materials, hydrocarbon-based electrolyte materials, etc., used as electrolyte materials for PEFCs can be used. For example, an ionomer that is a proton conductor can be used as the proton-conducting electrolyte, and typically a perfluorosulfonic acid polymer can be used. 【0025】 Perfluorosulfonic acid polymers are polymers in which side chains containing sulfonic acid groups are bonded to the main chain of a fluororesin. By introducing highly electronegative fluorine atoms, they become chemically very stable, have a high degree of dissociation of sulfo groups, and can achieve high proton conductivity. 【0026】 Suitable examples of commercially available perfluorosulfonic acid polymers include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and Aquivion (registered trademark, manufactured by Solvay). 【0027】 The electrode under test 11 has the shape of a rectangular parallelepiped with approximately square top and bottom surfaces. The size of the square is, for example, 1 cm on each side. In this embodiment, the top and bottom surfaces of the electrode under test 11 are square, but the top and bottom surfaces do not have to be square; they can be flat. 【0028】 (Proton-conducting membrane) The proton-conducting films 12a and 12b (first proton-conducting film, second proton-conducting film) sandwich the electrode 11 in the thickness direction. Specifically, the lower surface of the first proton-conducting film, proton-conducting film 12a, is in close contact with the upper surface of the electrode 11, and the upper surface of the second proton-conducting film, proton-conducting film 12b, is in close contact with the lower surface of the electrode 11. 【0029】 The proton-conducting films 12a and 12b have rectangular upper and lower surfaces, and the upper and lower surfaces of the proton-conducting films 12a and 12b have a larger area than the upper and lower surfaces of the electrode 11 under test. The proton-conducting films 12a and 12b are in close contact with each other, such that the center of the lower surface of the proton-conducting film 12a coincides with the center of the upper surface of the test electrode 11, and the center of the upper surface of the proton-conducting film 12b coincides with the center of the lower surface of the test electrode 11. Note that the upper and lower surfaces of the proton-conducting films 12a and 12b do not need to be rectangular, as long as they are flat. 【0030】 The proton-conducting membranes 12a and 12b can be electrolyte membranes used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers (see, for example, Japanese Patent Publication No. 6598159 and Japanese Patent Publication No. 6779470). In this embodiment, Nafion films are used as the proton-conducting films 12a and 12b, but other proton-conducting polymer films or proton-conducting ceramic films may also be used. 【0031】 Furthermore, the proton resistances in the thickness direction of the proton-conducting films 12a and 12b are either known or have been measured in advance. 【0032】 In this embodiment, the same Nafion film is used for the proton-conducting films 12a and 12b, but proton-conducting films with different materials and film thicknesses may be used as long as the objective of the present invention is not impaired. 【0033】 (Electronically conductive gas diffusion electrode) The gas diffusion electrodes 13a and 13b (first electron-conducting gas diffusion electrode and second electron-conducting gas diffusion electrode) sandwich the proton-conducting films 12a and 12b, which are holding the electrode 11 under test, in the thickness direction. Specifically, the lower surface of the gas diffusion electrode 13a is in close contact with the upper surface of the proton-conducting film 12a, and the upper surface of the gas diffusion electrode 13b is in close contact with the lower surface of the proton-conducting film 12b. 【0034】 The gas diffusion electrodes 13a and 13b are rectangular prisms with square top and bottom surfaces, and these squares are the same shape as the top and bottom surfaces of the electrode under test 11 (for example, squares with sides of 1 cm). The gas diffusion electrodes 13a and 13b are in close contact with each other such that the center of the bottom surface of the gas diffusion electrode 13a coincides with the center of the top surface of the proton conduction film 12a, and the center of the top surface of the gas diffusion electrode 13b coincides with the center of the bottom surface of the proton conduction film 12b. Note that the top and bottom surfaces of the gas diffusion electrodes 13a and 13b do not have to be square, as long as they are the same shape as the top and bottom surfaces of the electrode under test 11. 【0035】 The gas diffusion electrodes 13a and 13b are modeled after gas diffusion electrodes in known polymer electrolyte fuel cells and polymer electrolyte water electrolyzers (see, for example, Japanese Patent Publication No. 6598159 and Japanese Patent Publication No. 6779470), and consist of a catalyst layer where the electrode reaction occurs and a gas diffusion layer that diffuses the gaseous reaction-active substance (hydrogen gas) and reaction products (water vapor). Figure 2 shows schematic cross-sectional views of gas diffusion electrodes 13a and 13b. Gas diffusion electrode 13a has a structure in which catalyst layer 13a-1 and gas diffusion layer 13a-2 are superimposed in the thickness direction, and gas diffusion electrode 13b has a structure in which gas diffusion layer 13b-2 and catalyst layer 13b-1 are superimposed in the thickness direction. In other words, catalyst layers 13a-1 and 13b-1 are in close contact with proton conductive films 12a and 12b, respectively, and gas diffusion layers 13a-2 and 13b-2 are in close contact with electrodes 14a and 14b, respectively. 【0036】 In this embodiment, catalyst layers 13a-1 and 13b-1 have a structure in which electrode catalyst particles such as Pt are highly dispersed and supported on a support, for example, an electronically conductive carbon material. Gas diffusion layers 13a-2 and 13b-2 consist of, for example, a carbon material that functions as a current collector and a gas diffuser. 【0037】 By using gas diffusion electrodes 13a and 13b with such structures, it becomes possible to smoothly supply hydrogen to the upper or lower surface of the electrode 11 under test, thereby suppressing the effect of hydrogen diffusion resistance. 【0038】 Here, an example of a method for fabricating a measurement laminate (without a gas diffusion layer) consisting of the test electrode 11, proton-conducting membranes 12a and 12b, and catalyst layers 13a-1 and 13b-1 will be explained based on Figure 3. This fabrication method mimics the manufacturing method of membrane electrode assemblies (MEAs) used in known polymer electrolyte fuel cells and polymer electrolyte water electrolyzers. In this specification, a measurement laminate (without a gas diffusion layer) may be referred to as a "membrane electrode assembly." 【0039】 In this embodiment, the catalyst layers 13a-1 and 13b-1 of the test electrode 11 and the gas diffusion electrode are fabricated by spray printing. The method for fabricating the film electrode assembly (measurement laminate (without gas diffusion layer)) by spray printing will be described in detail in the examples. First, a dispersion that will form the basis of the test electrode 11 and the catalyst layers 13a-1 and 13b-1 is prepared. For example, as shown in Figure 3, (1) catalyst powder or carbon support powder is placed in a reagent bottle, and pure water, ethanol, and ionomer solution are added to it, and (2-1) a stirring bar is placed in the prepared dispersion and stirred with a stirrer. Then, (2-2) ultrasonic stirring is performed using an ultrasonic homogenizer to improve dispersibility. Heat is generated during this process, so it is cooled with ice water. Through these steps, a dispersion for spray printing is prepared. 【0040】 Next, (3) the prepared dispersion 24 is spray-printed onto the proton-conducting films 12a and 12b using a spray printing machine 29. Specifically, the catalyst layer 13a-1 is spray-printed onto the upper surface of the proton-conducting film 12a, the test electrode 11 is spray-printed onto the lower surface of the proton-conducting film 12a, and the catalyst layer 13b-1 is spray-printed onto the lower surface of the proton-conducting film 12b. After that, the proton-conducting film 12a with the catalyst layer 13a-1 and the test electrode 11 applied, and the proton-conducting film 12b with the catalyst layer 13b-1 applied, are allowed to air dry for a certain period of time (for example, overnight). 【0041】 (4) The proton conductive film 12a on which the catalyst layer 13a-1 and the electrode to be tested 11 are coated, and the proton conductive film 12b on which the catalyst layer 13b-1 is coated are superimposed so that the catalyst layer 13a-1, the electrode to be tested 11, and the catalyst layer 13b-1 are coaxially positioned, and pressed together by a hot press 30 for a predetermined time (for example, 190 seconds). 【0042】 Through the above process, a membrane electrode assembly (measuring laminate (without gas diffusion layer)) consisting of the test electrode 11, proton conductive films 12a and 12b, and catalyst layers 13a-1 and 13b-1 is fabricated. By inserting gas diffusion layers 13a-2 and 13b-2 into the upper and lower surfaces of this membrane electrode assembly, the target measuring laminate is fabricated. 【0043】 (1st electrode, 2nd electrode) Electrodes 14a and 14b (first electrode and second electrode) sandwich a measurement laminate consisting of the test electrode 11, proton conductive films 12a and 12b, and gas diffusion electrodes 13a and 13b in the thickness direction. Specifically, the lower surface of electrode 14a is in close contact with the upper surface of gas diffusion electrode 13a, and the upper surface of electrode 14b is in close contact with the lower surface of gas diffusion electrode 13b. 【0044】 The electrodes 14a and 14b in this embodiment utilize separators from a known PEFC cell holder. As the PEFC cell holder, for example, a cell holder for MEA developed under a New Energy and Industrial Technology Development Organization (NEDO) project can be used. Furthermore, in this embodiment, electrodes 14a and 14b have gas channels formed on the lower side of electrode 14a that is in close contact with the upper surface of gas diffusion electrode 13a, and on the upper side of electrode 14b that is in close contact with the lower surface of gas diffusion electrode 13b, allowing gas to flow into gas diffusion electrodes 13a and 13b, respectively. 【0045】 A proton resistance measurement system that uses a proton resistance measuring device 10 with such a structure to measure the proton resistance in the thickness direction of an electrode 11 under test will be described. Figure 4 shows an example configuration of the proton resistance measurement system 1 using the proton resistance measuring device 10 (enlarged schematic diagram of the area around the proton resistance measuring device 10). The overall configuration of the proton resistance measurement system used in the experiment will be described later in the Examples section. 【0046】 The proton resistance measurement system 1 includes a proton resistance measuring device 10, an evaluation device 40, and adjustment means 51 and 52. The proton resistance measuring device 10 is also equipped with tubes 31 to 34 for supplying and discharging gas. Gas is supplied to the proton resistance measuring device 10 via tubes 31 and 32, and gas is discharged from the proton resistance measuring device 10 via tubes 33 and 34. 【0047】 The adjustment means 51 and 52 are connected to the proton resistance measuring device 10 in tubes 31 and 32, respectively, and adjust the gas flow rate, temperature, and humidity in order to supply the proton resistance measuring device 10 with the appropriate amount of gas at the appropriate temperature and humidity. For example, the adjustment means 51 and 52 may be equipped with a flow meter, a humidifier, and a heater, and these may be used to adjust the gas flow rate, temperature, and humidity. 【0048】 As the gas supplied to the proton resistance measuring device 10, for example, in DC measurements, it is necessary to select a reaction with a small overpotential, and since the oxidation-reduction reaction of hydrogen in a hydrogen atmosphere is used, humidified hydrogen is used for the anode electrode (e.g., electrode 14a) and humidified nitrogen is used for the cathode electrode (e.g., electrode 14b). Furthermore, the proton resistance measuring device 10 is housed in a constant temperature chamber or the like so that the measurement laminate inside the proton resistance measuring device 10 maintains an appropriate temperature (80°C to 120°C). 【0049】 The evaluation device 40 measures the proton resistance in the thickness direction of the test electrode 11 within the proton resistance measuring device 10. Specifically, the evaluation device 40 measures the proton resistance using the current interruption method. 【0050】 The current interruption method is a method of measuring resistance from the voltage drop when the current is instantaneously interrupted. When measuring the proton resistance of the test electrode 11 in the measurement laminate, the measured value contains both ohmic components, where the current and voltage change linearly, and non-ohmic components, where the current and voltage change non-linearly. In order to calculate the proton resistance, which is the ohmic component, it is necessary to separate the ohmic and non-ohmic components. The current interruption method is used to perform this separation and calculate the proton resistance. 【0051】 The measurement laminate within the proton resistance measuring device 10 can be represented by an equivalent circuit composed of an ohmic resistance Rs, a charge transfer resistance Rp, and a double-layer capacitance Cd, as shown in Figure 5. In the current interruption method, the current I that is steadily flowing through such an equivalent circuit is instantaneously interrupted, and the time change of the voltage E at that moment is measured. Figure 6 is a waveform diagram showing the time change of voltage E when current I is instantaneously interrupted, with voltage E on the vertical axis and time t on the horizontal axis. As shown in Figure 6, when a steadily flowing current I is interrupted at time t1, the current I becomes 0, and the voltage (potential drop) across the ohmic resistor Rs becomes 0. However, the voltage across the charge transfer resistor Rp changes slowly due to the charge in the double-layer capacitance Cd, so no change is observed for several (tens) microseconds after the current is interrupted. Subsequently, the charge in the double-layer capacitance Cd is discharged through the charge transfer resistor Rp, so the voltage E drops nonlinearly from time t2 when the discharge begins, and reaches the open-circuit voltage. In such a voltage drop, the linear drop is caused by the ohmic resistor Rs, so the ohmic resistor Rs can be calculated by dividing the voltage difference ΔE (=E1-E2) in this drop by the value of the current I. 【0052】 The ohmic resistance Rs of the measurement laminate includes not only the proton resistance of the electrode 11 under test, but also the proton resistances of the proton-conducting films 12a and 12b. However, as mentioned above, since the proton resistances of the proton-conducting films 12a and 12b are known or have been measured in advance, the proton resistance of the electrode 11 under test can be calculated by subtracting the proton resistances of the proton-conducting films 12a and 12b from the ohmic resistance Rs. 【0053】 The evaluation device 40 is connected to electrodes 14a and 14b in the proton resistance measuring device 10 and is equipped with a DC current source for supplying current to the proton resistance measuring device 10, a switch for interrupting the current, and a voltmeter for measuring voltage. Using these, the proton resistance of the electrode under test 11 is determined by the current interruption method described above. 【0054】 While embodiments of the present invention have been described above with reference to the drawings, the embodiments disclosed herein are illustrative and not restrictive in all respects, and various other configurations can be adopted as long as they do not impair the purpose of the present invention. In particular, in the embodiments disclosed herein, matters not explicitly disclosed, such as various parameters, dimensions, weights, and volumes of components, do not deviate from what is normally practiced by those skilled in the art, and values ​​that can be easily anticipated by those skilled in the art can be adopted. 【0055】 For example, in the above embodiment, the proton resistance is measured using an electrode layer containing a proton-conducting electrolyte as the test electrode, but it is also possible to use an electrolyte membrane as the test electrode and measure the proton resistance of the electrolyte membrane. [Examples] 【0056】 The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. 【0057】 1. Preparation of the measurement laminate A measurement laminate similar to that shown in Figure 1 was fabricated. The following (A) and (B) were used for the test electrode 11, which was the measurement sample. (A): Electrode layer (Vulcan layer) consisting of a carbon support powder (Vulcan) without supporting Pt and a Nafion ionomer (5% Nafion, Aldrich) (B): Electrode layer (Pt / Vulcan layer) consisting of Pt-supported carbon carrier powder (Pt / Vulcan) and Nafion ionomer (5% Nafion, Aldrich) Furthermore, Nafion membranes (DuPont, Nafion 212, 4cm x 6cm, film thickness: 51μm) were used for the electrolyte membranes (first proton conducting membrane 12a and second proton conducting membrane 12b). In the catalyst layers 13a-1 and 13b-1 of the gas diffusion electrodes 13a and 13b, a standard catalyst (TEC10E50E, 46.5% Pt / KB, hereinafter referred to as "Pt / KB") manufactured by Tanaka Kikinzoku Co., Ltd. was used. 【0058】 Figure 3 shows the procedure for fabricating a measurement laminate using the spray printing method. First, a predetermined amount of catalyst powder or carbon support powder was placed in a reagent bottle, and a predetermined amount of ultrapure water, ethanol, and Nafion ionomer solution were added to obtain a dispersion. A stirring bar was placed in the obtained dispersion, and it was stirred with a stirrer for more than one hour. Next, to improve the dispersibility, ultrasonic stirring was performed using an ultrasonic homogenizer under ice cooling for 30 minutes. 【0059】 Next, the obtained dispersion was spray-printed onto the Nafion film (first proton conducting film 12a, second proton conducting film 12b) using a spray printing machine. As shown in Figure 3 (right), one Nafion film (corresponding to the first proton-conducting film 12a) was spray-printed with Pt / KB (anode, corresponding to catalyst layer 13a-1) on one side and the sample (corresponding to the test electrode 11) on the other side. The other Nafion film (corresponding to the second proton-conducting film 12b) was spray-printed with Pt / KB (cathode, corresponding to catalyst layer 13b-1) on only one side. In addition, during spray printing, the hot plate of the printing press was heated to 60°C to promote the evaporation of ultrapure water and ethanol. 【0060】 The coating area (electrode area) of the test electrode 11 (sample) and the gas diffusion electrodes 13a and 13b (Pt / KB) is 1 cm² each. 2 The anode and cathode (catalyst layers 13a-1, 13b-1) containing Pt had a Pt content of 0.3 mg Pt / cm³. 2 The electrodes were fixed in place, and even in the test electrode 11 (A) above, which does not contain Pt, the amounts of anode, cathode, and carbon support were made equal. 【0061】 After air-drying for at least one night following spray printing, a Nafion film with an electrode attached (first proton conducting film 12a) coated with Pt / KB (anode, corresponding to catalyst layer 13a-1) on one side and the sample (test electrode 11) on the other side, and a Nafion film with Pt / KB (cathode, corresponding to catalyst layer 13b-1) coated on only one side (second proton conducting film 12b) were assembled as a set. After overlapping these sets so that the coated portions were neatly aligned, a hot press was performed at 132°C and 0.3kN for 190 seconds to obtain a film electrode assembly (measurement laminate (without gas diffusion layer)) similar to that shown in Figure 1. Figure 7 shows an actual photograph of the fabricated film electrode assembly (measurement laminate (without gas diffusion layer)). At this stage, the film electrode assembly (measurement laminate (without gas diffusion layer)) has catalyst layer 13a-1 and catalyst layer 13b-1 (anode and cathode, respectively) on the outside, and does not have gas diffusion layer 13a-2 and gas diffusion layer 13b-2 (see Figure 2). 【0062】 The fabricated membrane electrode assemblies (measurement laminates (without gas diffusion layer)) are the following membrane electrode assemblies A and B. Membrane electrode assembly A: A membrane electrode assembly in which the test electrode 11 is "(A): an electrode layer (Vulcan layer) consisting of a carbon support powder (Vulcan) that does not support Pt and a Nafion ionomer". Membrane electrode assembly B: A membrane electrode assembly in which the test electrode 11 is made of a "carbon support powder (Pt / Vulcan) and an electrode layer (Pt / Vulcan layer) consisting of a Pt-supported carbon support powder (Pt / Vulcan) and a Nafion ionomer". 【0063】 A measurement laminate similar to that shown in Figure 1 was formed by placing carbon paper (untreated GDL) as gas diffusion layers 13a-2 and 13b-2 on the catalyst layers 13a-1 and 13b-1 (anode and cathode, respectively) of the fabricated membrane electrode assembly (measurement laminate (without gas diffusion layer)), thereby forming the first gas diffusion electrode 13a (catalyst layer 13a-1 and gas diffusion layer 13a-2) and the second gas diffusion electrode 13b (catalyst layer 13b-1 and gas diffusion layer 13b-2). This measurement laminate was then placed in a cell holder for MEA (NEDO jig, 1cm x 1cm) developed in a New Energy and Industrial Technology Development Organization (NEDO) project, and the measurement laminate was fixed to the cell holder by tightening it with a torque of 2.0 N·m, thereby obtaining a proton resistance measuring device 10 similar to that shown in Figure 1. 【0064】 Figure 8 is a photograph of the cell folder used for MEA in the experiment, showing (a) the flow channel portion of the separator and (b) an overall view of the cell folder. The separator corresponds to the first electrode 14a and the second electrode 14b in the proton resistance measuring device 10 in Figure 1. 【0065】 As shown in Figure 8(a), the separators (first electrode 14a, second electrode 14b) of the cell folder used have a structure with a gas channel (area 1 cm × 1 cm). These are positioned so as to be in close contact with the gas diffusion electrodes 13a and 13b (area 1 cm × 1 cm) of the measurement laminate, which corresponds to the reaction section of the PEFC. The gas channel has a structure with three serpentine channels, which supply the reaction gas (H2) and inert gas (N2) and allow water generated by the chemical reaction to be quickly discharged outside the cell. 【0066】 A cell folder for MEA (proton resistance measuring device 10) with a measurement laminate installed was placed in a proton resistance measuring system configured as shown in Figure 4. Figure 9 shows the configuration of the proton resistance measuring system used in the example. For the gas supplied to the proton resistance measuring device 10, it is necessary to select a reaction with low overpotential in DC measurements. Therefore, to utilize the oxidation-reduction reaction of hydrogen in a hydrogen atmosphere, humidified hydrogen was supplied to the anode side (second gas diffusion electrode 13b) and humidified nitrogen to the cathode side (first gas diffusion electrode 13a) of the measurement laminate placed in the proton resistance measuring device 10. (Note that in Figure 8(b), the overall cell folder diagram, the anode is on the bottom (cathode is on the top), unlike in Figure 9.) Measurements were performed using an electrochemical evaluation device (SP-240) manufactured by BioLogic as the evaluation device 40. 【0067】 <Evaluation Results> A measurement laminate containing a film electrode assembly A was used to evaluate the proton resistance of the electrode under test (electrode layer) contained therein. First, the measurement laminate, fixed to a cell holder, was placed in a constant temperature chamber (Yamato Scientific Co., Ltd., DKN302), and the gas supply tube and the wiring of the BioLogic electrochemical evaluation device (SP-240) were connected to the cell holder. It was confirmed that the cell temperature and gas humidification temperature were at the appropriate levels. To ensure proton conductivity by adequately hydrating the electrolyte membrane in the sample, a steady operation was performed for 1 hour while supplying sufficiently humidified anode and cathode gases (H2 and N2), after which the ohmic resistance of the measurement laminate (entire unit) was measured by the current interruption method. The ohmic resistance of the Nafion films (corresponding to the first proton-conducting film 12a and the second proton-conducting film 12b) constituting the measurement laminate was measured separately. The ohmic resistance of the electrode under test was calculated by subtracting the ohmic resistance of the Nafion films (the two films, the first proton-conducting film 12a and the second proton-conducting film 12b) from the ohmic resistance of the entire measurement laminate, and this was used as the proton resistance of the target electrode under test. 【0068】 The conditions for the current interruption method are as shown in Table 1. 【0069】 [Table 1] 【0070】 Table 2 shows the evaluation results. It was confirmed that the proton resistance measurement method of the present invention can quantitatively evaluate the proton resistance in the thickness direction of the electrode under test (an electrode layer containing an electrode material and a proton-conducting electrolyte). 【0071】 [Table 2] [Industrial applicability] 【0072】 The proton resistance measuring apparatus, proton resistance measuring system, and proton resistance measuring method of the present invention are industrially promising because they enable the quantitative measurement of proton resistance within an electrode layer containing an electrode material and a proton-conducting electrolyte. [Explanation of symbols] 【0073】 1. Proton Resistance Measurement System 10. Proton Resistance Measuring Device 11 Test electrode 12a First proton conducting membrane 12b Second proton-conducting membrane 13a First gas diffusion electrode 13b Second gas diffusion electrode 13a-1,13b-1 Catalyst layer 13a-2, 13b-2 Gas diffusion layer 14a 1st electrode 14b 2nd electrode 31, 32, 33, 34 tubes 40 Evaluation device 51,52 Adjustment means 40 Evaluation device 100 Proton Conduction Measuring Device 111, 112, 113, 114 Pt plates 120 Electrolyte membrane 131, 132 Nafion membrane 140 Electrode layer

Claims

[Claim 1] A proton resistance measuring device for measuring the proton resistance in the thickness direction of an electrode under test, which consists of an electrode layer containing an electrode material and a proton-conducting electrolyte, The electrode to be tested and, A first proton-conducting film and a second proton-conducting film sandwich the electrode to be tested in the thickness direction, The first proton-conducting film and the second proton-conducting film, which sandwich the electrode under test, are sandwiched in the thickness direction by a first electron-conducting gas diffusion electrode and a second electron-conducting gas diffusion electrode, A measuring laminate consisting of, The first electrode and the second electrode sandwich the aforementioned measuring laminate in the thickness direction, A proton resistance measuring device characterized by comprising the following features. [Claim 2] The proton resistance measuring device according to claim 1, wherein the electrode to be tested is composed only of an electronically conductive material without supported electrode catalyst particles and a proton-conducting electrolyte. [Claim 3] The proton resistance measuring device according to claim 1, wherein the first electrode and the second electrode have a gas flow path on the side that is in close contact with the first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode. [Claim 4] The proton resistance measuring device according to claim 1, wherein the first electron-conducting gas diffusion electrode and the second electron-conducting gas diffusion electrode each consist of a catalyst layer made of a carbon material on which electrode catalyst fine particles are supported and a gas diffusion layer made of a carbon material. [Claim 5] The proton resistance measuring device according to claim 1, wherein the first proton-conducting film and the second proton-conducting film are proton-conducting polymer films. [Claim 6] A proton resistance measuring device according to any one of claims 1 to 5, An evaluation device connected to the first and second electrodes, which performs a current interruption method, A proton resistance measurement system characterized by comprising the following features. [Claim 7] A method for measuring proton resistance, using the proton resistance measurement system described in claim 6, to measure the proton resistance in the thickness direction of an electrode under test, which consists of an electrode layer containing the electrode material and a proton-conducting electrolyte, by a current interruption method.

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