JP2005326311A - Ion conductivity measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion conductivity measuring method having improved stability and reproducibility of a measured value and higher accuracy in a film thickness direction 4-terminal method. <P>SOLUTION: Voltage electrodes 16, 17 are inserted between each solid electrolyte film 11-13 relative to the solid electrolyte films 11-13 laminated and arranged between two current electrodes 14, 15, and while supplying a current in the film thickness direction of the laminated solid electrolyte films 11-13 by the current electrodes 14, 15, ion conductivity of the solid electrolyte film 12 is measured based on the potential difference between the voltage electrodes 16, 17 arranged on both sides of the solid electrolyte film 12 which is a test film. In this case, a wire with good conductivity having the thickness of 1-15 μm (more preferably 5-10 μm) is used as each voltage electrode 16, 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ion conductivity measurement method for evaluating electrical conductivity characteristics of solid organic electrolyte membranes and solid inorganic electrolyte membranes having ion conductivity, particularly polymer solid electrolyte membranes applicable to fuel cells and the like. Is.

  In recent years, research on solid polymer electrolyte fuel cells using a polymer film of proton conductivity (ion conductivity) as an electrolyte has been advanced. Solid polymer electrolyte fuel cells operate at low temperatures, have high output density, and can be miniaturized, so they are promising as fuel cells for in-vehicle power supplies, household power supplies, and portables. Yes.

  At present, the main proton conductive membranes used in PEFC (Polymer Electrolyte Fuel Cell) are perfluoroalkylene as a main chain and a sulfone at the end of perfluorovinyl ether having a side chain. It is a fluororesin film having an ion exchange group such as an acid group or a carboxylic acid group. As such a fluororesin film, a Nafion (registered trademark) film, a Dow (registered trademark) film, an Aciplex (registered trademark) film, a Flemion (registered trademark) film, and the like are known. When evaluating the battery performance of these and newly developed membranes, one important indicator is the proton conductivity (ion conductivity) of the membrane.

  In addition, various inorganic or organic polymer films are used in high temperature solid oxide fuel cells suitable for high temperature operation, secondary batteries such as lithium batteries, and electrochemical sensors. In these polymer membranes, the ionic conductivity of oxides, lithium, etc. greatly affects the performance of the product. Therefore, when measuring the ionic conductivity, it is possible to measure at low cost, with good reproducibility, and accurately. There is a need for a measurement method that can be used.

  Currently, the measurement of the conductivity of the polymer proton exchange electrolyte membrane for fuel cells is mainly performed by the membrane surface direction four-terminal method (for example, Non-Patent Document 1).

  However, in a polymer proton exchange electrolyte membrane such as Nafion, the crystal structure and dimensional change in the membrane surface direction and the film thickness direction of the electrolyte membrane by processes such as stretching and hot pressing in the production and processing of the electrolyte membrane. In addition to anisotropy such as the above, there is a possibility that anisotropy may be brought about in ion conductivity (for example, Non-Patent Document 2). In addition, in solid polymer electrolyte fuel cells, these electrolyte membranes are used in the direction of film thickness and are evaluated for new anisotropic membranes. A method capable of measuring ion conductivity in the film thickness direction with high accuracy is required.

  Against this background, various methods have been studied and proposed as methods for measuring ion conductivity in the film thickness direction (film thickness direction measurement method). As a typical example, there are a conventional film thickness direction two-terminal method (for example, Non-Patent Document 3) and a film thickness direction four-terminal method (for example, Non-Patent Document 4).

In the film thickness direction two-terminal method as described in Non-Patent Document 3, due to the electrical multilayer complexity at the electrode / film interface (described in Non-Patent Document 5), a large number of Cole-Cole plots by the impedance method are used. The semicircular arc is sensitive to the effects of temperature and humidity, or is greatly affected by fabrication defects such as misalignment of both electrodes in the electrode / membrane assembly. For this reason, the film thickness direction two-terminal method has a problem that it is difficult to accurately read out the film body resistance R _bulk from the Cole-Cole plot.

Moreover, in the film thickness direction two-terminal measurement method for a plurality of stacked electrolyte membranes as described in Non-Patent Document 6, membrane body resistance R is obtained by fitting from a small number of readout points (about 5) on the Cole-Cole plot. _{Although bulk} is read out, the number of readout points is small, so the fitting error increases and accurate measurement cannot be performed.

  Compared to the film thickness direction two-terminal measurement method, the film thickness direction four-terminal method described in Non-Patent Document 4, Non-Patent Document 7, and the like has an advantage that measurement can be performed with high accuracy.

  Here, an ion conductivity measurement method for the solid electrolyte membrane to which the film thickness direction four-terminal method is applied will be described below with reference to FIGS. 14 (a) and 14 (b).

  FIG. 14A shows a side view of the arrangement relationship between the solid electrolyte membrane and the measurement electrode when the ionic conductivity is measured. In the above arrangement, solid electrolyte membranes 101 to 103, current electrodes 104 and 105, and voltage electrodes 106 and 107 are shown.

  The solid electrolyte membranes 101 to 103 are stacked between the current electrodes 104 and 105. FIG. 14B is a plan view seen from the stacking direction of the solid electrolyte membranes 101 to 103. The current electrodes 104 and 105 are arranged so that their regions overlap when viewed from the stacking direction.

  Regarding the voltage electrodes 106 and 107, the voltage electrode 106 is inserted between the solid electrolyte membranes 101 and 102, and the voltage electrode 107 is inserted between the solid electrolyte membranes 102 and 103. Further, the tips of the voltage electrodes 106 and 107 are arranged so as to exist in the arrangement region of the current electrodes 104 and 105 when viewed from the stacking direction. In the above arrangement, the solid electrolyte membrane 102 existing between the voltage electrodes 106 and 107 serves as a test membrane for measuring ionic conductivity.

  In FIG. 14 (a), the solid electrolyte membranes 101 to 103 and the voltage electrodes 106 and 107 are shown with a gap between the solid electrolyte membranes 101 to 103 so that the positional relationship is clear. Yes. However, in the actual measurement state, the solid electrolyte membranes 101 to 103 are disposed in contact with each other. In FIG. 14A, the voltage electrodes 106 and 107 do not have to overlap each other when viewed from the stacking direction.

  In order to measure the ionic conductivity of the test membrane (that is, the solid electrolyte membrane 102) in the above arrangement, a predetermined test current is applied to the stacked solid electrolyte membranes 101 to 103 by the current electrodes 104 and 105. As this test current, an AC wave, a step wave, a pulse wave or the like is used. In the state where the test current is applied, the voltage in the film thickness direction of the test film 102 is measured by the voltage electrodes 106 and 107.

  Here, when the distance between the voltage electrodes 106 and 107 is L, the area of the current electrodes 104 and 105 is A, and the resistance of the test film 102 obtained from the measurement results is R, the ion conductivity σ of the test film 102 is It is calculated | required from Formula (1). Note that the value of the resistor R is obtained from the current value that is input from the current electrodes 104 and 105 and the voltage value that is output from the voltage electrodes 106 and 107.

σ = L / RA (1)
Yoshitsugu Sone and two others "Proton Conductivity of Nafion 117 as Measured by a Four-Elecrode AC Impedance Method", J. Electrochem. Soc., Vol. 143, No. 4, 1996, 1254 Kevin M. Cable and two others "Anisotropic Ionic Conductivity in Uniaxially Oriented Perfluorosulfonate Ionomers", Chem. Mater., 7, 1995, 1601 BD Cahan and 1 other "AC Impedance Investigations of Proton Conduction in NafionTM", J. Electrochem. Soc., Vol. 140, No. 12, December 1993, p.185-186 Masahiro Watanabe and 3 others "Experimental analysis of water behavior in NafionTM electrolyte under fuel cell operation", Journal of Electroanalytical Chemistry 399, 1995, p.239-241 Arvind Parthasarathy and three others "The Platinum Microelectrode / Nafion Interface: An Electrochemical Impedance Spectroscopic Analysis of Oxygen Reduction Kinetics and Nafion Characteristics", J. Electrochem. Soc., Vol. 139, No. 6, 1992, 1634 J. Halim and 4 others "Characterization of Perfluorosulfonic Acid Membranes by Conductivity Measurements and Small-angle X-ray Scattering", Electrochimica Acta, Vol. 39, No. 8/9, 1994, 1303-1307 F N. Buchi and 1 other "Investigation of the Transversal Water Profile in Nafion Membranes in Polymer Electrolyte Fuel Cells", J. Electrochem. Soc., Vol. 148, No. 3, 2001, A183

  The above-described film thickness direction 4-terminal method can theoretically measure with higher accuracy than the film thickness direction 2-terminal method, but when actual measurement is performed using the conventional film thickness direction 4-terminal method, There is a factor that decreases the measurement accuracy, and there is a problem that accurate ion conductivity cannot be obtained.

  Specifically, the present inventors have confirmed that the contact state at the interface between the electrolyte membranes, or the contact state or contact area between the electrolyte membrane and the voltage electrode has a great influence on the measurement accuracy. In the conventional measuring method, these were not considered.

In the film thickness direction 4-terminal measurement method, the membrane body resistance R _bulk is read out by an oscilloscope using a current pulse method. In this case, however, the readout point cannot be directly viewed, and measurement precision cannot be sensed. In addition, there is a drawback that it is difficult to perform ion conductivity measurement by the film thickness direction 4-terminal measurement method.

  Also, the film thickness direction 4-terminal method has a smaller cell constant (Cell constant: L / A in σ = L / (RA)) due to a thinner film thickness and a larger film area than the film surface direction 4-terminal method. The resistance value (0.1 to 10Ω) obtained from the measurement is extremely lower than the resistance value (1000Ω or more) obtained by the film surface direction four-terminal method. For this reason, the influence of variation in resistance value is increased due to the non-uniformity inside the membrane assembly due to the contact state between the membranes and between the voltage electrode and the membrane, and the thickness of the voltage electrode. The relative error of becomes large. Alternatively, the contact area between the voltage electrode and the membrane generates an interfacial resistance and interfacial capacitance that is greater than the membrane body resistance, which causes a semicircular arc to appear in the Cole-Cole plot, eliminating the advantage in the 4-terminal method, and There is also a problem that the change in the semicircular arc is sensitive to temperature and humidity, making it difficult to measure the membrane body resistance from the intercept with the real axis in the Cole-Cole plot.

  The present invention has been made in view of the above problems, and its purpose is to improve the measurement value stability and reproducibility in the film thickness direction four-terminal method, and to provide a more accurate ion conductivity measurement method. It is to be realized.

  In order to solve the above-described problem, the ion conductivity measurement method according to the present invention inserts a voltage electrode between each solid electrolyte membrane with respect to at least three or more solid electrolyte membranes stacked between two current electrodes. The predetermined solid electrolyte membrane based on the potential difference between the voltage electrodes arranged on both sides of the predetermined solid electrolyte membrane while supplying current in the film thickness direction of the laminated solid electrolyte membrane by the current electrode In the ionic conductivity measurement method for measuring the ionic conductivity, a good conductive wire having no coating layer is used as the voltage electrode, and the thickness of the voltage electrode is 1 to 15 μm, more preferably 5 to 10 μm. It is characterized by being.

  According to said structure, the contact area of a voltage electrode and an electrolyte membrane is reduced by making the wire diameter of the said voltage electrode thinner than before, and, thereby, in a film thickness direction 4 terminal method, measurement value stability, It became possible to improve the reproducibility and implement a more accurate ion conductivity measurement method.

  In addition, in order to solve the above-described problem, another ion conductivity measurement method according to the present invention is provided between at least three solid electrolyte membranes stacked between two current electrodes. While inserting a voltage electrode and supplying a current in the film thickness direction of the stacked solid electrolyte membrane by the current electrode, the predetermined electrode based on the potential difference between the voltage electrodes arranged on both sides of the predetermined solid electrolyte membrane. In the ion conductivity measurement method for measuring the ionic conductivity of the solid electrolyte membrane, a good conductive wire having an insulating coating layer is used as the voltage electrode, and the thickness of the voltage electrode is preferably 50 to 150 μm, more preferably. Is characterized in that the thickness of the internal good conductive line is 30 to 70 μm.

  Even with the above configuration, the contact area between the voltage electrode and the electrolyte membrane is reduced, thereby improving the measurement value stability and reproducibility in the film thickness direction four-terminal method, and more accurate ion conductivity measurement. It became possible to carry out the method.

  In the ion conductivity measurement method, the current electrode, the solid electrolyte membrane, and the voltage electrode are joined by a compact method using pressure such as hot pressing, screwing, or screw plug, and the ion conductivity is measured. The measurement electrode / membrane assembly is preferably performed.

  According to the above configuration, by connecting the current electrode, the solid electrolyte membrane, and the voltage electrode by the above-described method, the contact state between the electrolyte membranes becomes better, and more accurate ion conductivity measurement is performed. Can be implemented.

  In the ion conductivity measuring method, it is preferable that the current electrode gives an input current by any one of AC impedance, current interruption, potential step, current, and potential pulse.

  Further, in the ion conductivity measuring method, it is preferable that the number of electrolyte membranes between the outer electrolyte membranes for introducing the current input by the current electrodes is 1 or more and 20 or less.

Moreover, in the said ion conductivity measuring method, the said current electrode, a solid electrolyte membrane, and a voltage electrode are the temperature of the range of 120-250 degreeC, and the range of 3.84 * 10 < ⁶ > -1.92 * 10 < ⁸ > Pa. It is preferable to join by hot pressing at a pressure, more preferably at a temperature in the range of 150 to 200 ° C., and at a pressure in the range of 3.84 × 10 ^{7 to} 1.44 × 10 ⁸ Pa.

  In the ion conductivity measurement method, the current electrode, the solid electrolyte membrane, and the voltage electrode are screwed or screwed with a torque in the range of 3 to 20 Nm, more preferably in the range of 5 to 15 Nm. It is preferable to join by this method.

  In the ion conductivity measuring method, the current electrode is preferably made of a highly conductive sheet made of any metal such as Au, Pt, platinum black, copper, or carbon.

  In the ionic conductivity measurement method, the voltage electrode is preferably disposed at an equipotential position between the electrolyte membranes.

  In the ionic conductivity measurement method, the voltage electrode is a well-conductive bare electrode having a thickness of 1 to 15 μm at a portion arranged in the current electrode arrangement region as seen from the stacking direction of the electrolyte membrane. Preferably, a wire is used, and the well-conductive bare wire is connected to a thicker conductive wire outside the current electrode arrangement region.

  In the ion conductivity measurement method, the length of the thin bare wire used in the portion arranged in the current electrode placement region is adjusted to 0.5 mm, and the tip of the thin wire is 0 between the current electrodes. It is preferable that it is disposed so as to be within a range of 0.1 to 0.2 mm and is joined by a compact method using pressure such as hot pressing, screwing, or screw plugging.

  Moreover, in the said ion conductivity measuring method, it is preferable to use the said voltage electrode in the state which shaved 0.1-0.2 mm the insulating coating layer in the front-end | tip part.

  Further, in the ion conductivity measuring method, the voltage electrode may be used in a state where a tip portion of a highly conductive wire having an insulating coating layer is cut obliquely or perpendicularly to the axial direction. preferable.

  Further, in the ion conductivity measuring method, a solution composed of the electrolyte membrane material and a solvent in which the electrolyte membrane material is dissolved is applied to a contact surface of the electrolyte membrane into which the voltage electrode is inserted, and the laminated electrolyte membrane and After the voltage electrode is vacuum dried, the joined body is manufactured. The electrolyte membrane is expanded with a solvent in which the electrolyte membrane is dissolved, and the laminated electrolyte membrane and the voltage electrode are vacuum dried, and then the joined body. Or, at the tip of the voltage electrode, make small spheres with a solution composed of the electrolyte membrane material and a solvent in which the electrolyte membrane material dissolves, dry the solvent of the spheres, and then stack the above It is preferable to manufacture the joined body after the electrolyte membrane and the voltage electrode are vacuum dried.

  According to said structure, the contact state of the said voltage electrode and electrolyte membrane becomes favorable, and more accurate ion conductivity measurement can be implemented.

  As described above, the ion conductivity measurement method according to the present invention improves the contact between the voltage electrode and the electrolyte membrane by reducing the contact area between the voltage electrode and the electrolyte membrane. Can achieve a better contact state than before, and can improve the stability and reproducibility of measured values in the film thickness direction four-terminal method, enabling the implementation of a more accurate ion conductivity measurement method. Play.

  An embodiment of the present invention will be described below with reference to FIGS. The present invention relates to an ion conductivity measuring method for evaluating electrical conductivity characteristics of a solid organic electrolyte membrane or solid inorganic electrolyte membrane having ion conductivity, particularly a polymer solid electrolyte membrane applicable to a fuel cell or the like. Is performed by the film thickness direction four-terminal method. In particular, the present invention aims to further improve accuracy in ion conductivity measurement by the film thickness direction four-terminal method.

  According to the present invention, an ionic conductivity measurement method using a film thickness direction four-terminal method includes laminating at least three polymer electrolyte membranes, two current electrodes, and at least two voltage electrodes. This is performed on the electrode / electrolyte membrane assembly to be arranged. First, the positional relationship between the electrolyte membrane and the electrode in this joined body will be described with reference to FIGS. 1 (a) and 1 (b).

  As shown in FIG. 1A, the joined body is composed of solid electrolyte membranes 11 to 13, current electrodes 14 and 15, and voltage electrodes 16 and 17, and the solid electrolyte membranes 11 to 13 are current electrodes. 14 and 15 are stacked. Regarding the voltage electrodes 16 and 17, the voltage electrode 16 is inserted between the solid electrolyte membranes 11 and 12, and the voltage electrode 17 is inserted between the solid electrolyte membranes 12 and 13. That is, the voltage electrode is inserted between each of the two solid electrolyte membranes.

  FIG. 1A illustrates a configuration in which three solid electrolyte membranes are stacked, so the number of voltage electrodes is two. However, in a configuration in which N solid electrolyte membranes are stacked, the voltage electrode The number is (N-1). In the above-mentioned joined body, an electrolyte membrane (here, solid electrolyte membrane 12) sandwiched between two voltage electrodes serves as a test membrane for measuring ionic conductivity. Here, the electrolyte membranes on both outer sides of the joined body are arranged for the purpose of introducing an alternating current into the joined body, and about 1 to 20 test membranes are arranged between the electrolyte membranes on both outer sides. It can be. At this time, it is also possible to measure the ionic conductivity for each of the test films or for every several sheets, thereby reducing the measurement error and further improving the measurement accuracy.

  FIG. 1B is a plan view of the solid electrolyte membranes 11 to 13 as viewed from the stacking direction, and the current electrodes 14 and 15 are arranged so that their regions overlap when viewed from the stacking direction. Further, the tips of the voltage electrodes 16 and 17 are arranged so as to exist in the arrangement region of the current electrodes 14 and 15 when viewed from the stacking direction. In FIG. 1B, the voltage electrodes 16 and 17 do not have to overlap each other when viewed from the stacking direction.

  In FIG. 1A, the solid electrolyte membranes 11 to 13 and the voltage electrodes 16 and 17 are illustrated with a space between the solid electrolyte membranes 11 to 13 so that the positional relationship is clear. Yes. However, in the actual measurement state, the solid electrolyte membranes 11 to 13 are arranged in contact with each other. The joined body is obtained by joining the electrolyte membrane and the electrode in the above-described arrangement by a compact method using pressure such as hot pressing, screwing, or screw plug.

  In order to measure the ionic conductivity of the test membrane (that is, the solid electrolyte membrane 12) with respect to the joined body, a predetermined test current is applied to the laminated solid electrolyte membranes 11 to 13 by the current electrodes 14 and 15. As this test current, AC impedance (sine wave), current interruption, potential step (step wave), current, potential pulse (pulse wave), etc. are used. In the state where the test current is applied, the voltage in the film thickness direction of the test film 12 is measured by the voltage electrodes 16 and 17.

  As the current electrodes 14 and 15, it is preferable to use a metal such as Au, Pt, platinum black, copper, aluminum, nickel, titanium, and stainless steel, or a highly conductive sheet such as carbon.

  The voltage electrodes 16 and 17 are made of a highly conductive wire such as metal or carbon, and may or may not have an insulating coating layer such as Teflon (registered trademark) or resin. The voltage electrodes 16 and 17 are disposed at equipotential positions between the electrolyte membranes, and sample and extract potential signals between the membranes. The tips of the voltage electrodes 16 and 17 are preferably near the center of the current electrode arrangement region, and are arranged in a circular or square shape corresponding to the circular or square shape of the current electrode.

  As described above, the present invention aims to further improve the accuracy in ion conductivity measurement by the film thickness direction four-terminal method, but the contact state at the interface between the electrolyte membranes or the electrolyte membrane and the voltage electrode As described above, the contact state and the contact area exist as causes for reducing the measurement accuracy.

  For example, in the conventional film thickness direction 4-terminal method, the thickness of the conductive wire used for the voltage electrode is not considered, and a wire of about several tens of μm is used for the voltage electrode. For example, in Non-Patent Document 4, a 25 μm conductive wire is used as a voltage electrode.

  However, when the diameter of the voltage electrode inserted between the electrolyte membranes is large, a gap is generated between the electrolyte membranes, and the contact area between the voltage electrode and the electrolyte membrane increases, and this gap and the increased contact area. The semi-circular arc due to the resistance and electric capacity from this causes the variation of the measured value. Therefore, in the present invention, in the joined body shown in FIG. 1, the gap between the electrolyte membranes is minimized, and the contact area between the voltage electrode and the electrolyte membrane is reduced so that a good contact surface can be obtained. An attempt was made to make the conductive wires used as the voltage electrodes 16 and 17 thinner than before. As a result, it was found that when a good conductive wire such as metal or carbon having no coating layer is used, the thickness is 1 to 15 μm, preferably 5 to 10 μm, and good results are obtained.

  In the case of using a highly conductive wire such as Teflon (registered trademark) or a resin having an insulating coating layer such as resin or carbon, the thickness is 50 to 150 μm, preferably 50 to 100 μm, and the thickness of the internal conductive wire. 30-70 μm, it was found that good results were obtained.

  In FIG. 1A, the solid electrolyte membranes 11 to 13 and the voltage electrodes 16 and 17 are illustrated with a space between the solid electrolyte membranes 11 to 13 so that the positional relationship is clear. Yes. However, in the actual measurement state, the solid electrolyte membranes 11 to 13 are arranged in contact with each other. The joined body is obtained by joining.

Moreover, in the above-mentioned joined body, in order to improve the contact state at the interface between the electrolyte membranes or the contact state between the electrolyte membrane and the voltage electrode, the electrolyte membrane and the electrode are hot pressed, screwed, screw plugs, etc. Join with the compact method. Suitable conditions for performing this joining by hot pressing are a temperature of 120 to 250 ° C., preferably 150 to 200 ° C., and a pressure of 3.84 × 10 ^{6 to} 1.92 × 10 ⁸ Pa, preferably 3. It is 84 * 10 < ⁷ > -1.44 * 10 < ⁸ > Pa.

  Moreover, as for the suitable conditions in the case of performing this joining by screwing or performing with a screw plug, temperature is 120-250 degreeC, Preferably it is 150-200 degreeC, A torque is 3-20 Nm, Preferably it is 5-15 Nm.

  In the above-described overlap compact method by pressure such as screwing and screw plug, the hot pressing of the joined body and the assembly into the cell are performed consistently for a specific cell according to the above-described conditions. It is preferable because instability of the voltage electrode inside the joined body due to the secondary operation (displacement of the electrode, etc.) can be avoided.

  In the above description, the contact state at the interface between the electrolyte membranes, or the contact state between the electrolyte membrane and the voltage electrode and the contact area have a great influence on the measurement accuracy. Even if the contact state with the electrolyte membrane is poor, the measurement results vary. As a method for improving the contact state between the current electrode and the electrolyte membrane, the electrolyte membrane material is formed on the side in contact with the electrolyte membrane in the conductive sheet that becomes the current electrode in the step of stacking the electrolyte membrane / electrode assembly. And a solution comprising a solvent that dissolves it and drying it. The above method is preferable because it can improve the contact between the current electrode / electrolyte membrane, make the electric field between the current electrodes uniform, and obtain an accurate and reproducible measurement value.

  The present invention reduces the contact area between the voltage electrode and the electrolyte membrane, and closes the contact between the voltage electrode, the electrolyte membrane, and the test membrane, thereby interfacial electricity between the voltage electrode and the electrolyte membrane. Suppresses the influence of capacitance and resistance, and suppresses the semicircular arc on the Cole-Cole plot by the impedance method. Thereby, in this invention, the measurement precision by a film thickness direction 4 terminal method can be improved.

  As a method for reducing the contact area between the voltage electrode and the electrolyte membrane, for example, the following configuration of the voltage electrode can be considered.

  First, when the voltage electrode does not have a coating layer, that is, when a well-conductive bare wire such as metal or carbon is used as the voltage electrode, as shown in FIG. It is preferable to manufacture the electrolyte membrane / electrode assembly by a compact method using a pressure such as hot pressing, screwing, screw plug, or the like in a state where the current electrode is placed in a range of 0.1 to 0.2 mm.

  Moreover, in the said joined body which concerns on this invention, since a sufficiently thin line | wire is used conventionally in a voltage electrode, the resistance value becomes large. In order to improve this, as shown in FIG. 3, only the portion of the voltage electrode inserted between the current electrodes is thinned, and the voltage electrode composed of the thin line portion is made conductive such as a ribbon line or a thick line. It can be considered to connect to the sex wire and pull out to the outside.

  In addition, in the structure which connects a thin wire | line and a ribbon wire in the said voltage electrode, it is necessary to also make the contact property in this connection part favorable. For this reason, in the above configuration, the thin wire is wound around the thick wire (for example, a platinum wire having a diameter of 100 μm or a platinum ribbon having a width of 0.15 cm and a thickness of 10 μm), and the wound portion is used as the solvent for the electrolyte membrane material and the solvent. It is possible to improve the contact between the voltage electrode and the external cable by wrapping with a thin film having a thickness of 1 to 5 μm made of a solution consisting of

  When using the thick / thin composite wire as described above as the voltage electrode, as shown in FIG. 4, the tip of the thin wire is adjusted to a length of 0.5 mm, and the electrolyte membrane has a margin of 1 mm or more from the current electrode. In between, the tip of the thin wire is placed so as to be 0.1 to 0.2 mm between the two current electrodes, and the electrolyte membrane / electrode assembly is compacted by a pressure such as hot pressing or screwing or screw plug. Manufacturing.

  In addition, when a highly conductive wire such as Teflon (registered trademark) or a metal having an insulating coating layer such as resin or carbon is used as the voltage electrode, a conductive wire of 0.1 to 0.2 mm is exposed. Thus, the insulating coating layer at the tip can be shaved and used (see FIG. 5). At this time, the tip of the voltage electrode from which the good conductive line is exposed is disposed at an equipotential position between the electrolyte membranes, preferably at the center of the current electrode and the position near the center, and the electrolyte membrane / electrode assembly is manufactured. The

  In addition, when using a highly conductive wire such as Teflon (registered trademark) or a resin having an insulating coating layer such as resin or carbon as the voltage electrode, instead of scraping the insulating coating layer at the tip, the insulating coating layer is used. A line having a layer may be cut obliquely (see FIG. 6) or vertically (see FIG. 7), and the internal good conductive line may be exposed at the cut surface. In this case as well, the tip of the voltage electrode from which the good conductive line is exposed is disposed at an equipotential position between the electrolyte membranes, preferably at the center of the current electrode and in the vicinity of the center, and the electrolyte membrane / electrode assembly is manufactured. Is done.

  In manufacturing the electrolyte membrane / electrode assembly, as described above, the solution is applied to the contact surface between the current electrode and the electrolyte membrane in order to improve the contact state between the current electrode and the electrolyte membrane. Furthermore, in order to improve the contact between the voltage electrode, the electrolyte membrane, and the electrolyte membrane, the above solution can also be used.

  In this case, for example, in the stage of manufacturing the electrolyte membrane / electrode assembly, 1 to 5 μl, preferably 1 to 2 μl, of a 5 wt% solution composed of the electrolyte membrane material and a solvent for dissolving the electrolyte membrane material is generated in the electrolyte membrane. 1), apply the electrolyte membrane and electrodes with a Teflon (registered trademark) sheet, glass slide, etc. in the order shown in FIG. 1 and fix them with a clip. After vacuum drying at 80 ° C. for 48 hours, the hot press Alternatively, a method of manufacturing an electrolyte membrane / electrode assembly by a compact method using pressure such as screwing or screw plugging can be employed.

  Alternatively, in the step of manufacturing the electrolyte membrane / electrode assembly, a conductive wire to be a voltage electrode is inserted between the electrolyte membranes expanded with the solvent, and air bubbles between the electrolyte membranes are removed from the center by hand. After pressing, the electrolyte membrane and electrode are sandwiched in the order of FIG. 1 with a Teflon (registered trademark) sheet, glass slide, etc., fixed with a clip, vacuum dried at 80 ° C. for 48 hours, and then hot-pressed and twisted. Alternatively, a method of manufacturing an electrolyte membrane / electrode assembly by a compact method using pressure such as a screw plug can be employed.

  Further alternatively, in the step of manufacturing the electrolyte membrane / electrode assembly, a small sphere made of the solution is formed at the tip of the voltage electrode, the solvent is air-dried at room temperature, and further vacuum-dried at room temperature for 1 hour. Thereafter, the tip of the voltage electrode is disposed at an equipotential position between the electrolyte membranes, and an electrolyte membrane / electrode assembly is manufactured by a compact method using pressure such as hot pressing, screwing, or screw plug. be able to. The solution for forming small spheres at the tip of the voltage electrode is, for example, 0.01 to 0.05 μl, preferably 0.01 to 0.02 μl of a 5 wt% solution comprising an electrolyte membrane material and a solvent for dissolving the electrolyte membrane material. A solution of about 60 wt% made by volatilizing the solvent can be used.

  Hereinafter, the present invention will be described in detail with reference to the following examples. However, the following examples do not limit the present invention.

[Example 1]
Two polyester-coated copper wires having an outer diameter of φ100 μm having a length of about 4 cm were prepared and used as voltage electrodes. At the tip of this voltage electrode, the 0.1 to 0.2 mm covering layer is scraped to expose the internal conductive wires, and one voltage electrode is arranged on each side of the test membrane (Nafion 117). Inserted between electrolyte membranes. Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the opposite direction in a state where the tip portion was separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As current electrodes, two square sheets of platinum foil having a thickness of 10 μm were prepared, and a 5 wt% Nafion solution was uniformly applied thereto at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried square platinum foil sheet, that is, the current electrode is disposed on both surfaces of the above-described three-layered electrolyte membrane, and hot-pressed at 150 ° C. and 800 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrodes are arranged such that the center points of the tips of both coated copper wires, which are voltage electrodes, are superimposed on the center point of a rectangular sheet.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. The call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plot results are shown in FIGS.

[Example 2]
A platinum wire having an outer diameter of φ10 μm was cut to a length of about 1 cm, and this was wound around a 0.15 × 4 cm platinum ribbon cut from a platinum foil having a thickness of 10 μm, and this wound portion was made of a 5 wt% Nafion solution. A voltage electrode was formed by wrapping with a thin film having a thickness of 3 μm and fixing by hot pressing at 150 ° C. and 400 kg / cm ² . Further, in the voltage electrode using the thick / thin composite wire, a thin platinum wire of φ10 μm at the tip thereof was adjusted to a length of 0.05 cm.

Two voltage electrodes were prepared from the adjusted thick / thin composite wire, and the voltage electrodes were inserted between the electrolyte membranes so as to be arranged one on each side of the test membrane (Nafion 117). Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the same direction in a state where the tip portions were separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As current electrodes, two square sheets of platinum foil having a thickness of 10 μm were prepared, and a 5 wt% Nafion solution was uniformly applied thereto at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried square platinum foil sheet, that is, the current electrode is disposed on both surfaces of the above-described three-layered electrolyte membrane, and hot-pressed at 150 ° C. and 800 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrodes have both voltage electrodes parallel to the center lines of both sides of the square sheet, and the center points of the tips of both voltage electrodes are along the center lines of both sides of the square sheet. The front ends are arranged so as to overlap each other in a square sheet by about 0.1 to 0.2 mm.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. The call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plot results are shown in FIGS.

Example 3
Two polyester-coated copper wires having an outer diameter of 100 μm were prepared with a length of about 4 cm, and one end thereof was obliquely cut to form a voltage electrode. Furthermore, a small sphere having a wall thickness of about 20 μm is formed at one end of the voltage electrode obliquely cut with a solution of about 60 wt% prepared by volatilizing the solvent from 0.02 μl, 5 wt% Nafion solution, and at room temperature. The solvent was air-dried and then vacuum-dried at room temperature for 1 hour.

The voltage electrodes with Nafion spheres attached to the tip were inserted between the electrolyte membranes so that one was placed on each side of the test membrane (Nafion 117). Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the opposite direction in a state where the tip portion was separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As a current electrode, two square sheets of 20 μm-thick platinum foil were prepared, and a 5 wt% Nafion solution was uniformly applied thereon at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried rectangular platinum foil sheet, that is, the current electrode, is disposed on both surfaces of the above-described three-layer electrolyte membrane, and hot-pressed at 150 ° C. and 800 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrodes are arranged such that the center points of the tips of both coated copper wires, which are voltage electrodes, are superimposed on the center point of a rectangular sheet.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. The call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plot results are shown in FIGS. 10 (a) to 10 (c) and calculated from the resistance values. The film thickness direction ion conductivity is shown in FIG. 11 together with the data obtained by the film surface four-terminal method.

  Further, some comparative examples for the present invention are shown below.

[Comparative Example 1]
Two platinum wires having an outer diameter of φ100 μm having a length of about 4 cm were prepared and used as voltage electrodes. The voltage electrodes were inserted between the electrolyte membranes so that one voltage electrode was placed on each side of the test membrane (Nafion 117). Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the opposite direction in a state where the tip portion was separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As current electrodes, two square sheets of platinum foil having a thickness of 10 μm were prepared, and a 5 wt% Nafion solution was uniformly applied thereto at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried square platinum foil sheet, that is, the current electrode is disposed on both surfaces of the above-described three-layered electrolyte membrane, and hot-pressed at 150 ° C. and 800 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrode is arranged such that the center point of the tip end of the platinum wire as the voltage electrode is overlapped with the center point of the rectangular sheet.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. The call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plot results are shown in FIGS.

[Comparative Example 2]
Two Teflon (registered trademark) -coated platinum wires having an outer diameter of φ180 μm (inner diameter of φ127 μm) were prepared with a length of about 4 cm, and one end of which was obliquely cut was used as a voltage electrode. The voltage electrodes, whose tips were cut obliquely, were inserted between the electrolyte membranes so as to be arranged one by one on both sides of the test membrane (Nafion 117). Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the opposite direction in a state where the tip portion was separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As current electrodes, two square sheets of platinum foil having a thickness of 10 μm were prepared, and a 5 wt% Nafion solution was uniformly applied thereto at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried rectangular platinum foil sheet, that is, the current electrode is disposed on both surfaces of the above-described three-layered electrolyte membrane, and hot-pressed at 150 ° C. and 200 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrode is arranged such that the center point of the tips of both coated platinum wires, which are voltage electrodes, is superimposed on the center point of the rectangular sheet.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. In this case, the contact between the voltage electrode and the electrolyte membrane was poor, and the measuring device was overloaded, so that the Cole-Cole plot was disturbed and measurement could not be performed.

[Comparative Example 3]
Two Teflon (registered trademark) -coated platinum wires having an outer diameter of φ180 μm (inner diameter of φ127 μm) were prepared with a length of about 4 cm, and one end of which was obliquely cut was used as a voltage electrode. Furthermore, a small sphere having a wall thickness of about 20 μm is formed at one end of the voltage electrode obliquely cut with a solution of about 60 wt% prepared by volatilizing the solvent from 0.02 μl, 5 wt% Nafion solution, and at room temperature. The solvent was air-dried and then vacuum-dried at room temperature for 1 hour.

The voltage electrodes with Nafion spheres attached to the tip were inserted between the electrolyte membranes so that one was placed on each side of the test membrane (Nafion 117). Further, the two voltage electrodes were arranged such that the wire main body was placed in parallel in the opposite direction in a state where the tip portion was separated by 0.05 cm vertically. The electrolyte membrane and the voltage electrode were pressed and fixed at a pressure of 20 kg / cm ² .

As current electrodes, two square sheets of platinum foil having a thickness of 10 μm were prepared, and a 5 wt% Nafion solution was uniformly applied thereto at 20 μl / cm ² and vacuum-dried at room temperature for 1 hour.

The dried rectangular platinum foil sheet, that is, the current electrode is disposed on both surfaces of the above-described three-layered electrolyte membrane, and hot-pressed at 150 ° C. and 200 kg / cm ² for 10 minutes, so that the electrolyte for ion conductivity measurement A membrane / electrode assembly was produced. The current electrode is arranged such that the center point of the tips of both coated platinum wires, which are voltage electrodes, is superimposed on the center point of the rectangular sheet.

  The electrolyte membrane / electrode assembly is assembled in a specific conductivity measurement cell, placed in an environment of 30 ° C. and 30% RH, and using an Solar 1100 SI 1260 Impedance analyzer and SI 1287 Electrochemical interface, an amplitude of 10 mV, The ionic conductivity of the test membrane between the two voltage electrodes was measured with an AC signal having a frequency of 5 MHz to 0.1 Hz. The call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plot results are shown in FIGS.

  Here, first, Examples 1 and 2 and Comparative Example 1 are compared.

  In Comparative Example 1, a bare platinum wire having a diameter of 100 μm is used as the voltage electrode. In this case, as shown in FIG. 12A, three semicircular arcs appear in the Cole-Cole plot, and there are almost no concentrated points. Therefore, the resistance of the test membrane body cannot be read.

  On the other hand, in Example 1, a polyester-coated copper wire having an outer diameter of φ100 μm obtained by cutting a coating layer of 0.1 to 0.2 mm is used as a voltage electrode. In this case, as shown in FIG. A concentration point exists in the Cole-Cole plot, and the resistance of the test membrane body can be read out.

  Furthermore, in Example 2, a thick / thin composite wire composed of a fine platinum wire having a diameter of 10 μm and a platinum ribbon is used as a voltage electrode. In this case, as shown in FIG. Concentration points exist in a narrower range than in the case of 1, and the resistance of the test film body can be read with higher accuracy.

  According to the comparison results of Examples 1 and 2 and Comparative Example 1, the contact area between the voltage electrode and the electrolyte membrane greatly affects the measurement accuracy in the measurement of ion conductivity by the film thickness direction 4-terminal method. I understood.

Subsequently, Example 3 and Comparative Examples 2 and 3 are compared. In Comparative Example 2, the electrolyte membrane / electrode assembly was produced by hot pressing at 150 ° C. and 200 kg / cm ² , but the contact between the voltage electrode and the electrolyte membrane was poor, and the measuring device sometimes overloaded. The Cole-Cole plot was disturbed and measurement was not possible.

  On the other hand, in Comparative Example 3, a Nafion sphere having a wall thickness of about 20 μm is formed at the tip of the voltage electrode (Teflon (registered trademark) -coated platinum wire having an outer diameter of φ180 μm), thereby forming a gap between the voltage electrode and the electrolyte membrane. The contact was improved and measurement was possible as shown in FIG.

  Furthermore, in Example 3, the voltage electrode was a polyester-coated copper wire having an outer diameter of φ100 μm, and the tip thereof was provided with Nafion globules in the same manner as in Comparative Example 3. By reducing the wire diameter of the voltage electrode in this way, the contact area and contact stability between the voltage electrode and the electrolyte membrane are greatly improved, and the influence of the capacitance and contact resistance at the interface is greatly reduced. For this reason, as shown in FIG. 10 (a), in the Cole-Cole plot, there are concentrated points in a narrower range than in the case of Comparative Example 3, and the resistance of the test film body can be read out with higher accuracy.

  Further, referring to FIG. 11, in the Nafion 117, the measurement in an environment of 30 ° C. and 30% RH gives an ion conductivity measurement value almost in agreement with the result obtained from the film surface direction four-terminal method. The effectiveness of the present invention has been demonstrated.

FIG. 1A shows an embodiment of the present invention, FIG. 1A is a side view showing an electrode / electrolyte membrane assembly in a film thickness direction 4-terminal method, and FIG. It is a top view which shows an electrode / electrolyte membrane assembly. It is a top view which shows an example of arrangement | positioning relationship between the current electrode and voltage electrode in the said conjugate | zygote. It is a top view which shows another example of the arrangement | positioning relationship between the current electrode and voltage electrode in the said conjugate | zygote. It is a top view which shows an example of the arrangement | positioning relationship between the current electrode in the said conjugate | zygote, a voltage electrode, and an electrolyte membrane. It is a figure which shows an example of the front-end | tip part of the said voltage electrode at the time of using the electroconductive wire which has a coating layer for the said voltage electrode. It is a figure which shows another example of the front-end | tip part of the said voltage electrode at the time of using the electroconductive wire which has a coating layer for the said voltage electrode. It is a figure which shows another example of the front-end | tip part of the said voltage electrode at the time of using the electroconductive wire which has a coating layer for the said voltage electrode. FIGS. 8A to 8C are graphs showing the results of call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plots in Example 1. FIG. FIGS. 9A to 9C are graphs showing the results of call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plots in Example 2. FIG. FIGS. 10A to 10C are graphs showing the results of call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plots in Example 3. FIG. In Example 3, it is a graph which compares the film thickness direction ion conductivity calculated from the measured resistance value with the data obtained by the conventional film surface 4 terminal method. 12A to 12C are graphs showing the results of plotting Cole-Cole (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) in Comparative Example 1. FIG. FIGS. 13A to 13C are graphs showing the results of call-call (Z′-Z ″) and board (log | Z | -log Frequency and theta-log Frequency) plots in Comparative Example 3. FIG. FIG. 14 (a) is a side view showing an electrode / electrolyte membrane assembly in the film thickness direction 4-terminal method, and FIG. 14 (b) is an electrode / electrolyte in the film thickness direction 4-terminal method. It is a top view which shows the structure of a membrane assembly.

Explanation of symbols

11-13 Solid electrolyte membranes 14, 15 Current electrodes 16, 17 Voltage electrodes

Claims (21)

With respect to at least three or more solid electrolyte membranes arranged between two current electrodes, a voltage electrode is inserted between the solid electrolyte membranes, and current flows in the film thickness direction of the laminated solid electrolyte membranes by the current electrodes. In the ion conductivity measurement method for measuring the ionic conductivity of the predetermined solid electrolyte membrane based on the potential difference between the voltage electrodes arranged on both sides of the predetermined solid electrolyte membrane while supplying
A method of measuring ion conductivity, wherein a good conductive wire having no coating layer is used as the voltage electrode, and the thickness of the voltage electrode is 1 to 15 μm.   The thickness of the said voltage electrode is 5-10 micrometers, The ion conductivity measuring method of Claim 1 characterized by the above-mentioned. With respect to at least three or more solid electrolyte membranes arranged between two current electrodes, a voltage electrode is inserted between the solid electrolyte membranes, and current flows in the film thickness direction of the laminated solid electrolyte membranes by the current electrodes. In the ion conductivity measurement method for measuring the ionic conductivity of the predetermined solid electrolyte membrane based on the potential difference between the voltage electrodes arranged on both sides of the predetermined solid electrolyte membrane while supplying
An ion characterized in that a good conductive wire having an insulating coating layer is used as the voltage electrode, the thickness of the voltage electrode is 50 to 150 μm, and the thickness of the internal good conductive wire is 30 to 70 μm. Conductivity measurement method.   The thickness of the said voltage electrode is 50-100 micrometers, The ion conductivity measuring method of Claim 3 characterized by the above-mentioned.   The current electrode, the solid electrolyte membrane, and the voltage electrode are joined by a compact method using pressure such as hot pressing, screwing, or screw plug, and the ionic conductivity is measured with respect to the electrode / membrane assembly for measurement. The ion conductivity measuring method according to claim 1, wherein the ion conductivity measuring method is performed.   6. The ion conductivity measuring method according to claim 1, wherein the current electrode gives an input current by any one of AC impedance, current interruption, potential step, current, and potential pulse.   The ion according to any one of claims 1 to 6, wherein the number of electrolyte membranes between the outer electrolyte membranes for introducing a current input by the current electrode is 1 or more and 20 or less. Conductivity measurement method. The current electrode, the solid electrolyte membrane, and the voltage electrode are bonded by hot pressing at a temperature in the range of 120 to 250 ° C. and a pressure in the range of 3.84 × 10 ^{6 to} 1.92 × 10 ⁸ Pa. The ionic conductivity measuring method according to claim 5. The current electrode, the solid electrolyte membrane, and the voltage electrode are bonded by a hot press technique at a temperature in the range of 150 to 200 ° C. and a pressure in the range of 3.84 × 10 ^{7 to} 1.44 × 10 ⁸ Pa. The ionic conductivity measuring method according to claim 5, wherein:   6. The ion conductivity measurement according to claim 5, wherein the current electrode, the solid electrolyte membrane, and the voltage electrode are joined by a screwing or screw plug technique with a torque in the range of 3 to 20 Nm. Method.   6. The ion conductivity measurement according to claim 5, wherein the current electrode, the solid electrolyte membrane, and the voltage electrode are joined by a screwing or screw plug technique with a torque in the range of 5 to 15 Nm. Method.   The ion conductivity measurement according to any one of claims 1 to 11, wherein the current electrode is made of a highly conductive sheet made of any metal such as Au, Pt, platinum black, copper, or carbon. Method.   The ion conductivity measuring method according to claim 1, wherein the voltage electrode is disposed at an equipotential position between electrolyte membranes.   As the voltage electrode, a good conductive bare wire having a thickness of 1 to 15 μm is used in a portion arranged in the current electrode placement region as viewed from the stacking direction of the electrolyte membrane, and the good conductive bare wire The ion conductivity measuring method according to claim 1, wherein the ionic conductivity is connected to a thicker conductive wire outside the current electrode arrangement region.   In the voltage electrode, the length of the fine bare wire used in the portion arranged in the current electrode arrangement region is adjusted to 0.5 mm, and the tip of the fine wire is 0.1 to 0.2 mm between the two current electrodes. The ion conductivity measurement method according to claim 14, wherein the ion conductivity measurement method is arranged so as to enter, and is joined by a compact method using pressure such as hot pressing, screwing, or screw plugging.   4. The ion conductivity measuring method according to claim 3, wherein the voltage electrode is used in a state where the insulating coating layer at the tip thereof is cut by 0.1 to 0.2 mm.   4. The ion conductivity measuring method according to claim 3, wherein the voltage electrode is used in a state in which a tip portion of a highly conductive wire having an insulating coating layer is cut obliquely with respect to the axial direction thereof. .   4. The ion conductivity measuring method according to claim 3, wherein the voltage electrode is used in a state in which a leading end portion of a highly conductive wire having an insulating coating layer is cut perpendicularly to an axial direction thereof. .   After applying a solution composed of the electrolyte membrane material and a solvent in which the electrolyte membrane material is dissolved to the contact surface of the electrolyte membrane into which the voltage electrode is inserted, the laminated electrolyte membrane and the voltage electrode are vacuum-dried, and then the bonding The ion conductivity measuring method according to claim 5, wherein the body is manufactured.   6. The ionic conduction according to claim 5, wherein the electrolyte membrane is expanded with a solvent in which the electrolyte membrane dissolves, and the laminated electrolyte membrane and voltage electrode are vacuum-dried, and then the joined body is manufactured. Degree measurement method.   At the tip of the voltage electrode, a small sphere is made with a solution composed of the electrolyte membrane material and a solvent in which the electrolyte membrane material is dissolved, the solvent of the small sphere is dried, and the stacked electrolyte membrane and voltage electrode are further attached. The ion conductivity measuring method according to claim 5, wherein the joined body is manufactured after vacuum drying.

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