JP2010271291A - Device and method for measuring ionic conductivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for measuring ionic conductivity that improves the working efficiency, by simplifying the connecting work of an electrolyte film to four electrodes for measurement and reduces the material cost required for measurement, when the ionic conductivity of the thickness direction of the electrolyte film is measured by a four-terminal method. <P>SOLUTION: The device 5 for measuring the ionic conductivity includes a first measuring tool 11, having a first electrode 21 for an ammeter coming into contact with the electrolyte film 80 via a first conductive external film 41; a second measuring tool 12 having a second electrode 22 for an ammeter coming into contact with the electrolyte film 80 via a second conductive external film 42; a first electrode for a voltmeter arranged between the electrolyte film and the first external film; and a second electrode 32 for a voltmeter arranged between the electrolyte film and the second external film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ion conductivity measuring device and an ion conductivity measuring method.

  The performance of an electrolyte membrane used in a polymer electrolyte fuel cell or the like can be evaluated by ionic conductivity in the film thickness direction of the electrolyte membrane. For measurement of ion conductivity, a measurement method by a two-terminal method or a four-terminal method is generally employed.

  Compared to the measurement method using the two-terminal method, the measurement method using the four-terminal method is less affected by the internal resistance of the measuring instrument and the connection resistance caused by the connection between the measurement object and the measurement electrode, and provides more accurate ion conduction. Allows measurement of degrees. When the measurement method using the four-terminal method is used to measure the ionic conductivity in the film thickness direction of the electrolyte membrane, a thin film electrolyte membrane to be measured, a set of ammeter electrodes, and a set of voltmeters It is necessary to make electrical connection of the electrodes for use.

  In the invention described in Patent Document 1, measurement is performed by a four-terminal method using two conductive dummy films embedded with voltmeter electrodes (see Patent Document 1). Two dummy films are made to function as ammeter electrodes, and a potential difference in the film thickness direction of the electrolyte film is measured by a voltmeter electrode embedded in the dummy film. At the time of measurement, the electrolyte membrane is sandwiched between two dummy membranes, and these are integrated by hot pressing to electrically connect the electrolyte membrane and the four measurement electrodes.

JP2007-298388

  In the measurement method based on the above four-terminal method, it is possible to ensure electrical connection between the thin-film electrolyte membrane and the four measurement electrodes. However, it is difficult to improve the working efficiency of the measurement work because hot pressing is performed to integrate a plurality of films each time the ion conductivity of the electrolyte membrane is measured. In addition, when performing measurement on different electrolyte membranes, it is necessary to prepare a dummy membrane and a voltmeter electrode separately, which increases the material cost required for measurement.

  Therefore, the object of the present invention is to simplify the connection work between the electrolyte membrane and the four measuring electrodes and improve the working efficiency when measuring the ion conductivity in the film thickness direction of the thin electrolyte membrane by the four-terminal method. In addition, an object of the present invention is to provide an ion conductivity measuring device and an ion conductivity measuring method capable of reducing the material cost required for measurement.

  The present invention is an ion conductivity measuring device that measures ion conductivity in the film thickness direction of an electrolyte membrane by a four-terminal method. A first measuring jig in which a first ammeter electrode is placed in contact with the electrolyte membrane via a conductive first external membrane; and an electrolyte membrane via a conductive second external membrane. A second measuring jig having a second ammeter electrode in contact therewith, a first voltmeter electrode disposed between the electrolyte membrane and the first external membrane, an electrolyte membrane, And a second voltmeter electrode disposed between the two outer membranes. Then, by arranging the first and second measurement jigs so as to sandwich the electrolyte membrane in the film thickness direction between the first ammeter electrode and the second ammeter electrode, the electrolyte membrane On the other hand, the first and second ammeter electrodes and the first and second voltmeter electrodes are electrically connected to each other.

  The present invention is also a method for measuring ionic conductivity in which the ionic conductivity in the film thickness direction of the electrolyte membrane is measured by a four-terminal method. The electrolyte membrane is sandwiched between the first ammeter electrode arranged on the first measurement jig and the second ammeter electrode arranged on the second measurement jig in the film thickness direction. The first and second measuring jigs are arranged so as to avoid this. Thus, the first and second ammeter electrodes are electrically connected to the electrolyte membrane via the conductive first and second outer membranes, respectively, and the electrolyte membrane and the first and second electrodes are connected. The first and second voltmeter electrodes arranged between each of the outer membranes are electrically connected to the electrolyte membrane.

  According to the present invention, the first and second voltmeter electrodes, the first and second outer membranes, and the electrolyte membrane are disposed to overlap between the first and second ammeter electrodes, The electrolyte membrane and the four measurement electrodes can be electrically connected by a simple operation of sandwiching the electrode between the first and second measurement jigs. For this reason, while being able to improve the work efficiency of the connection operation | work required for the measuring method by a 4 terminal method, the material cost required for a measurement can be reduced.

It is a figure which simplifies and shows the measuring apparatus of ion conductivity. 2A is an exploded perspective view showing the first and second measuring jigs, FIG. 2B is an enlarged view of the broken line portion of FIG. FIG. 2C is a view showing the ammeter electrode 1 as viewed from the direction of arrow 2C in FIG. 2B. It is a perspective view for demonstrating a pressurization means. 4A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 4B is an arrow view seen from the direction of arrow 4B in FIG. 4A. FIG. 5A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 5B is an arrow view seen from the direction of arrow 5B in FIG. 5A. 6A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 6B is an arrow view seen from the direction of arrow 6B in FIG. 6A. FIG. 7A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 7B is an arrow view seen from the direction of arrow 7B in FIG. 7A. FIG. 8A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 8B is an arrow view seen from the direction of arrow 8B in FIG. 8A. FIG. 9A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 9B is an arrow view seen from the direction of arrow 9B in FIG. 9A. FIG. 10A is a plan view for explaining a measurement method using an ion conductivity measuring device, and FIG. 10B is an arrow view seen from the direction of arrow 10B in FIG. 10A. It is a figure which shows the measurement result of the electroconductivity of an electrolyte membrane. It is a figure which shows the result of the evaluation test of the battery performance of a membrane electrode assembly.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  1-3, the ion conductivity measuring apparatus 5 according to the embodiment will be outlined. The ion conductivity in the film thickness direction of the electrolyte membrane 80 (vertical direction indicated by arrow a in FIG. 1) is represented by 4 terminals. A device for measuring ion conductivity 5 measured by the method, wherein the first ammeter electrode 21 that is in contact with the electrolyte membrane 80 via the conductive first outer membrane 41 is disposed. The jig 11, the second measuring jig 12 in which the second ammeter electrode 22 contacting the electrolyte membrane 80 via the conductive second external film 42 is disposed, the electrolyte membrane 80, A first voltmeter electrode 31 disposed between the first outer membrane 41 and a second voltmeter electrode 32 disposed between the electrolyte membrane 80 and the second outer membrane. Have. By arranging the first and second measuring jigs 11 and 12 so as to sandwich the electrolyte membrane 80 in the film thickness direction between the first ammeter electrode 21 and the second ammeter electrode 22. The first and second ammeter electrodes 21 and 22 and the first and second voltmeter electrodes 31 and 32 can be electrically connected to the electrolyte membrane 80, respectively ( (See also FIG. 9).

  The first and second measurement jigs 11 and 12 include a through hole 51 for supplying the water vapor v to the electrolyte membrane 80 and a vapor channel 53 communicating with the through hole 51 around the electrolyte membrane 80. And a groove 52 for the steam channel to be formed (corresponding to a groove for forming the steam channel) (see also FIG. 10).

  Further, the first and second ammeter electrodes 21, 22 have a planar shape extending in the surface direction of the electrolyte membrane 80. The first and second voltmeter electrodes 31 and 32 are composed of conductive electrode wires having no coating film. The first and second voltmeter electrodes 31 and 32 are arranged so as to intersect with each other with the electrolyte membrane 80 interposed therebetween. The first and second outer membranes 41 and 42 have an elastic modulus smaller than that of the electrolyte membrane 80.

  The ion conductivity measuring device 5 is provided with a pressurizing means 70 that applies pressure to the film thickness direction of the electrolyte membrane 80. The pressurizing unit 70 tightens the first and second measuring jigs 11 and 12 with a screw member 71 (corresponding to a fastening unit) and applies pressure to the film thickness direction of the electrolyte membrane 80 (FIG. 3). See also).

  In the embodiment, the measuring apparatus and the measuring method of the present invention are applied to the measurement of ion conductivity in the film thickness direction of the electrolyte membrane 80 used in the polymer electrolyte fuel cell. For the measurement, measurement was performed by a four-terminal method using four measurement electrodes, ie, first and second ammeter electrodes 21 and 22 and first and second voltmeter electrodes 31 and 32. Yes.

  Hereinafter, embodiments will be described in detail.

  Referring to FIG. 1, the ion conductivity measuring device 5 includes first and second measuring jigs 11 and 12 on which an electrolyte membrane 80 is disposed, a measuring instrument 6 that measures the impedance of the electrolyte membrane 80, have.

  As the measuring instrument 6, an impedance analyzer generally used for impedance measurement is used. The measuring instrument 6 supplies a current to the electrolyte membrane 80 by the first and second ammeter electrodes 21 and 22, while the first and second voltmeter electrodes 31 and 32 supply the current to the electrolyte membrane 80. And the impedance of the electrolyte membrane 80 are measured.

  The measuring instrument 6 determines the resistance value R of the electrolyte membrane 80 based on the measurement result. The ion conductivity σ is the resistance value R of the electrolyte membrane 80, the thickness t1 of the electrolyte membrane 80, the width w of the electrolyte membrane 80, and the distance d between the first and second voltmeter electrodes 31 and 32. Based on the calculation formula (σ = d / (R · t1 · w) [S / m]), the calculation is performed (see FIGS. 6B and 8B).

  A previously created operation control program can be input to the measuring instrument 6 to automatically perform the above-described ion conductivity measurement operation. In the measurement, after the connection work between the electrolyte membrane 80 and the measurement electrode is completed, the first and second measurement jigs 11 and 12 are arranged in a constant temperature and humidity chamber (not shown), Carry out under humidity and temperature conditions.

  The first and second ammeter electrodes 21, 22 are electrically connected to a current system terminal 8 provided in the measuring instrument 6. For the connection, cables generally used for electrode connection can be used. In the illustrated example, a known electrode cable 7 provided with a clip for connection is used. The first and second voltmeter electrodes 31 and 32 are electrically connected to a voltage system terminal 9 provided in the measuring instrument 6. For the connection, the same type of electrode cable 7 used for connecting the ammeter electrodes 21 and 22 can be used.

  Next, the first measurement jig 11 will be described. The first and second measuring jigs 11 and 12 are used as a pair in measurement, and there is no significant difference in configuration. For this reason, the first measurement jig 11 will be described in detail, and a part of the description of the second measurement jig 12 will be omitted.

  With reference to FIG. 2 and FIG. 3, the first measurement jig 11 includes a set of jig constituent pieces 13 including a first jig constituent piece 13 and a second jig constituent piece 14. 14 is connected. A screw member 71 is used for the connection. When connecting, the connecting operation is performed while the positioning pin 15 is inserted into the positioning hole 73. This is because the connecting work can be performed smoothly.

  The first and second jig constituting pieces 13 and 14 are provided with a current electrode groove portion 16 for attaching the first ammeter electrode 21. The current electrode groove 16 is formed on the connecting end face 74 where the first and second jig constituting pieces 13 and 14 face each other. The first ammeter electrode 21 is fitted into the groove 16 for the current electrode of the first jig constituting piece 13 or the second jig constituting piece 14. The attachment can be performed by a simple operation by fitting into the groove 16 for the current electrode.

  The first jig constituting piece 13 and the second jig constituting piece 14 are connected in a state in which the first ammeter electrode 21 is fitted in the groove portion 16 for the current electrode, and the first measuring jig 11 is connected. Make up. The first ammeter electrode 21 is sandwiched between the connecting end faces 74. By this sandwiching, the first ammeter electrode 21 is fixed to the first measuring jig 11.

  The first ammeter electrode 21 is electrically connected to the first electrode portion 25 that is electrically connected to the electrolyte membrane 80 via the first outer film 41, and the current system terminal 8 of the measuring instrument 6. It has the 2nd electrode part 26 connected, and the convex part 27 which prevents the drop from the groove part 16 for current electrodes.

  The first electrode portion 25 is formed in a planar shape extending in the surface direction of the electrolyte membrane 80. This is because the contact area between the first electrode portion 25 and the electrolyte membrane 80 is increased. At the time of measurement, the outer shape of the electrolyte membrane 80 or the first outer membrane 41 may be deformed due to swelling or the like. Even in such a case, the electrical connection between the electrolyte membrane 80 and the first ammeter electrode 21 can be stably maintained. Variations in measurement results can be prevented, and more reliable measurement results can be obtained.

  The convex portion 27 provided on the first ammeter electrode 21 prevents the projection from the groove portion 16 for the current electrode. If the first ammeter electrode 21 falls out of the current electrode groove 16, the connecting work takes time and work delays are caused. By forming the convex portion 27, it is possible to prevent a work delay that may occur during the connecting work.

  As the first and second ammeter electrodes 21 and 22, platinum electrodes generally used as electrodes are used. The outer dimensions are such that the thickness dimension t2 is about 0.7 mm and the height dimension h is about 10 mm (see FIG. 2B). The material, outer shape, and the like of the first and second ammeter electrodes 21 and 22 are not limited to those described above, and can be changed as appropriate.

  When measuring the ionic conductivity, the first and second measuring jigs 11 and 12 are arranged facing each other so as to sandwich the electrolyte membrane 80 in the film thickness direction. The portion of the electrolyte membrane 80 sandwiched between the first and second ammeter electrodes 21 and 22 and further sandwiched between the first and second voltmeter electrodes 31 and 32 has ion conductivity. It becomes a measurement site 81 (see FIG. 9).

  Management of the humidity and temperature around the measurement site 81 is performed by supplying water vapor v from the through holes 51 provided in the first and second measurement jigs 11 and 12 (see FIG. 10). A steam channel 53 communicating with the through-hole 51 can be formed at a portion where the groove portions 52 for the steam channel provided in the first and second measuring jigs 11 and 12 face each other. Yes. The steam channel 53 makes it possible to sufficiently distribute the water vapor v around the measurement site 81. As a result, the humidity and temperature state at the measurement site 81 can be managed with high accuracy, and the ion conductivity simulating the set measurement environment can be measured.

  An inclined surface 18 is provided between the flat portion 17 where the first ammeter electrode is disposed and the through hole 51. The water vapor v supplied from the through hole 51 is guided by the inclined surface 18 to increase the supply amount of the water vapor v around the measurement site 81.

  When measuring the ionic conductivity of the electrolyte membrane 80, a laminated structure for measuring the ionic conductivity is formed between the first and second measuring jigs 11 and 12. A first outer film 41 is arranged in the film thickness direction on the first ammeter electrode 21 arranged in the first measurement jig 11. A first voltmeter electrode 31 is disposed on the first outer film 41, and an electrolyte film 80 that is a measurement target is disposed on the first voltmeter electrode 31. A second voltmeter electrode 32 is disposed on the electrolyte membrane 80, and a second external film 42 is disposed on the second voltmeter electrode 32. Then, the second measurement jig 12 is disposed so as to sandwich the electrolyte membrane 80 between the first ammeter electrode 21 and the second ammeter electrode 22 (see FIG. 9).

  The first ammeter electrode 21 and the electrolyte membrane 80 are electrically connected via the first outer membrane 41. The second ammeter electrode 22 and the electrolyte membrane 80 are electrically connected via the second external membrane 42. By making the first ammeter electrode 21 and the second ammeter electrode 22 conductive, it is possible to apply an electric current to the electrolyte membrane 80 to be measured.

  The first and second voltmeter electrodes 31 and 32 are in direct contact with and electrically connected to the electrolyte membrane 80. The first and second voltmeter electrodes 31 and 32 can measure the potential difference in the film thickness direction of the electrolyte membrane 80. The first voltmeter electrode 31 and the first ammeter electrode 21 are brought into contact with each other through the first outer film 41. This prevents both from contacting directly and conducting. Similarly, the second voltmeter electrode 32 and the second ammeter electrode 22 are in contact with each other via the second outer film 42.

  As described above, the first and second voltmeter electrodes 31 and 32, the first and second outer films 41 and 42, and the electrolyte film between the first and second ammeter electrodes 21 and 22. 80 are arranged in an overlapping manner, and electrical connection necessary for measurement of ion conductivity by the four-terminal method is performed by a simple operation of sandwiching them between the first and second measuring jigs 11 and 12. Is possible. The first and second measuring jigs 11 and 21 and other members required for measurement can be shared for different electrolyte membranes 80.

  Referring to FIG. 3, the first and second measuring jigs 11 and 12 have a pressurizing unit 70 that applies pressure in the film thickness direction of the electrolyte membrane 80. The electrolyte membrane 80 is sandwiched between the first ammeter electrode 21 disposed on the first measurement jig 11 and the second ammeter electrode 22 disposed on the second measurement jig 12. However, if excessive pressure is applied in the film thickness direction due to this sandwiching, there is a possibility that plastic deformation occurs in the electrolyte membrane 80. Further, at the time of measurement, the electrolyte membrane 80 may swell due to the supplied water vapor v, and the film thickness dimension t1 may change (see FIG. 6B). When the film thickness dimension t1 changes, the distance d between the first and second voltmeter electrodes 31 and 32 also changes. Changes in the film thickness dimension t1 and the distance d between the first and second voltmeter electrodes 31 and 32 affect the measurement result of ion conductivity. Therefore, by providing the pressurizing means 70, the pressure applied to the electrolyte membrane 80 in the film thickness direction can be adjusted, and the deformation amount of the electrolyte membrane 80 in the film thickness direction is adjusted. This makes it possible to obtain a more reliable measurement result. Furthermore, by using the pressurizing means 70, it becomes possible to carry out measurements under different pressure conditions.

  The pressurizing means 70 has a screw member 71 for tightening the first and second measuring jigs 11 and 12 in the film thickness direction, and a screw hole 72. The screw hole 72 is formed so as to penetrate the first measurement jig 11 and the second measurement jig 12 in the film thickness direction. The amount of torque is controlled by the pressurizing means 70 and the pressure applied to the electrolyte membrane 80 is adjusted. The pressure can be adjusted by a simple method using the screw member 71, and work delays that can occur with the use of the pressurizing means 70 can be reduced.

  The first and second measurement jigs 11 and 12 can be fixed by a screw member 71. The work of fixing both can be performed simultaneously with the adjustment of the pressure applied in the film thickness direction, and the work efficiency required for the measurement can be improved. When the first and second measuring jigs 11 and 12 are fixed, the fixing operation is performed while the positioning pins 15 are inserted into the positioning holes 73. This is because the fixing work can be performed smoothly.

  As the first and second outer films 41 and 42, conductive ion permeable films are used. There are no particular restrictions on the material and shape of the ion permeable membrane, but it is desirable that the ion permeable membrane be formed in an outer shape that does not block the through-hole 51 when placed on the first ammeter electrode 21. This is because the water vapor v supplied from the through hole 51 can be spread around the measurement site 81.

  When a force for sandwiching the first and second voltmeter electrodes 31 and 32 in the film thickness direction is applied, the first and second voltmeter electrodes 31 and 32 are buried in the electrolyte membrane 80, and There is a possibility that the distance d between the first and second voltmeter electrodes 31 and 32 may change. In order to prevent such a change in the distance d between the first and second voltmeter electrodes 31, 32, the first and second outer films 41, 42 are made of elastic modulus of the electrolyte membrane 80. It is formed so as to have a smaller elastic modulus. The first and second outer films 41 and 42 having an elastic modulus smaller than that of the electrolyte membrane 80 are deformed so as to wrap the first and second voltmeter electrodes 31 and 32 in the film thickness direction, The first and second voltmeter electrodes 31 and 32 are prevented from being buried in the electrolyte membrane 80. Therefore, even when the force sandwiched in the film thickness direction is excessively applied, the distance d between the first and second voltmeter electrodes 31 and 32 can be prevented from changing, and the measurement result It is possible to prevent a decrease in reliability. The elastic modulus values of the first and second outer films 41 and 42 are not particularly limited. It is only necessary to have a smaller elastic modulus than at least the elastic modulus of the electrolyte membrane 80, and it is possible to select appropriately within this range.

  As the first and second voltmeter electrodes 31 and 32, conductive electrode wires are used. As the electrode wire, it is possible to select a thin copper wire or the like processed into a wire shape. By using a widely used electrode wire, the material cost can be reduced. The formation of the coating film on the electrode wire is omitted, and the material cost is further reduced. Since thin electrode wires are used for the first and second voltmeter electrodes 31 and 32, the area where the first and second voltmeter electrodes 31 and 32 are in contact with each other can be reduced. . As a result, the difference between the thickness t1 of the electrolyte membrane 80 and the distance d between the first and second voltmeter electrodes 31, 32 can be reduced, and a more reliable measurement result can be obtained. Is possible. For example, it is desirable to use an electrode wire having an outer diameter of about 1 to 50 μm.

  The first and second voltmeter electrodes 31 and 32 are disposed so as to be in point contact with each other with the electrolyte membrane 80 interposed therebetween. By arranging in this way, when a force is applied to the first and second voltmeter electrodes 31 and 32 in the direction of sandwiching the electrolyte membrane 80, the force is applied to a portion other than the point-contacted portion. It is possible to relieve pressure. It is possible to prevent the voltmeter electrodes 31 and 32 from coming into contact with each other in a wide range around the measurement site 81, and to increase the supply amount of water vapor v to the measurement site 81. Further, by arranging the first and second voltmeter electrodes 31 and 32 in point contact with each other, the first and second ammeter electrodes 21 and 22 and the first and second voltmeter electrodes. It can prevent more reliably that 31 and 32 contact accidentally.

  A part of the first and second voltmeter electrodes 31 and 32 is disposed in the voltage electrode groove 19 provided in the first and second measuring jigs 11 and 12, and is a resinous adhesive. It can be fixed by other simple methods.

  Next, the operation will be described.

  Referring to FIGS. 4A and 4B, a first measuring jig 11 configured by connecting a first jig constituting piece 13 and a second jig constituting piece 14 is prepared. The first outer film 41 is disposed on the first ammeter electrode 21.

  With reference to FIGS. 5A and 5B, the first voltmeter electrode 31 is disposed on the first outer films 41 and 42. The first voltmeter electrode 31 is disposed so as to pass through the center position of the first ammeter electrode 21 and is fixed by an adhesive or the like in the groove portion 19 for the voltage electrode.

  The first voltmeter electrode 31 and the first ammeter electrode 21 are brought into contact with each other through the first outer film 41. The two are prevented from direct contact and conduction.

  With reference to FIGS. 6A and 6B, an electrolyte membrane 80 to be measured is disposed on the first voltmeter electrode 31.

  Since the first electrode portion 25 extending in the surface direction of the electrolyte membrane 80 is formed in the first ammeter electrode 21, the contact area between the electrolyte membrane 80 and the first ammeter electrode 21 is increased. Can be made. It is possible to stably maintain the electrical connection between the electrolyte membrane 80 and the first ammeter electrode 21 and to obtain a more reliable measurement result.

  With reference to FIGS. 7A and 7B, the second voltmeter electrode 32 is disposed on the electrolyte membrane 80.

  The second voltmeter electrode 32 is disposed so as to be in point contact with the first voltmeter electrode 31 with the electrolyte membrane 80 interposed therebetween. The second voltmeter electrodes 31 and 32 are fixed in the voltage electrode groove 19.

  The first and second voltmeter electrodes 31 and 32 are arranged in point contact with each other to prevent them from coming into contact with each other in a wide range around the measurement site 81. It is possible to increase the supply amount of water vapor v to the measurement site 81.

  Since thin electrode wires are used for the first and second voltmeter electrodes 31 and 32, it is possible to reduce the area where the first and second voltmeter electrodes 31 and 32 are in contact with each other. It has become. It is possible to reduce the difference between the thickness t1 of the electrolyte membrane 80 and the distance d between the first and second voltmeter electrodes 31 and 32.

  In the electrolyte membrane 80, a portion sandwiched between the first voltmeter electrode 31 and the second voltmeter electrode 32 becomes a measurement portion 81 for measuring ion conductivity.

  With reference to FIGS. 8A and 8B, the second outer film 42 is disposed on the second voltmeter electrode 32.

  The first and second outer films 41 and 42 are formed to have an elastic modulus smaller than that of the electrolyte membrane 80. The first and second outer films 41, 42 are deformed so as to wrap the first and second voltmeter electrodes 31, 32 in the film thickness direction, and the first and second voltmeter electrodes 31, 32. Is prevented from being buried in the electrolyte membrane 80. This prevents the distance d between the first and second voltmeter electrodes 31 and 32 from changing.

  With reference to FIGS. 9A and 9B, the second measurement is performed so that the electrolyte membrane 80 is sandwiched between the first ammeter electrode 21 and the second ammeter electrode 22 in the film thickness direction. A jig 12 is arranged.

  The second ammeter electrode 22 and the second voltmeter electrode 32 are brought into contact with each other through the second outer film 42. The two are prevented from direct contact and conduction.

  The first ammeter electrode 21 and the electrolyte membrane 80 are electrically connected via the first outer membrane 41. The second ammeter electrode 22 and the electrolyte membrane 80 are electrically connected via the second external membrane 42. By making the first ammeter electrode 21 and the second ammeter electrode 22 conductive, it is possible to apply an electric current to the electrolyte membrane 80 to be measured.

  The first and second voltmeter electrodes 31 and 32 are in direct contact with and electrically connected to the electrolyte membrane 80. The first and second voltmeter electrodes 31 and 32 can measure the potential difference in the film thickness direction of the electrolyte membrane 80.

  Here, as a known technique, a measurement method by a four-terminal method using two conductive dummy films in which electrodes for a voltmeter are embedded is used for measuring ion conductivity in the film thickness direction of a thin-film electrolyte film. It has been known. In this measurement method, the electrolyte membrane is sandwiched between two dummy membranes and integrated by hot pressing to electrically connect the electrolyte membrane and the four measurement electrodes. When this method is adopted, it is possible to ensure electrical connection between the thin electrolyte membrane and the four measurement electrodes, but every time the ion conductivity of the electrolyte membrane is measured. It is necessary to perform hot pressing to integrate a plurality of films. Therefore, it is difficult to improve the work efficiency of the measurement work. Furthermore, when performing measurements on different electrolyte membranes, it is necessary to prepare a dummy membrane and a voltmeter electrode separately, which increases the material cost required for the measurement.

  On the other hand, in the present embodiment, the first and second voltmeter electrodes 31, 32, the first and second outer films are provided between the first and second ammeter electrodes 21, 22. 41 and 42 and the electrolyte membrane 80 are arranged in an overlapping manner, and the electrolyte membrane 80 and the four measurement electrodes are electrically connected by a simple operation of sandwiching them between the first and second measurement jigs 11 and 12. Can be connected. For this reason, when measuring the ion conductivity in the film thickness direction by the four-terminal method, the work efficiency of the connection work can be improved. The first and second measuring jigs 11 and 21 and other members required for measurement can be shared for different electrolyte membranes 80. Therefore, it is possible to reduce the material cost required for measurement when repeatedly used.

  The first and second measuring jigs 11 and 12 are fixed to each other by a screw member 71. The amount of torque is adjusted by the screw member 71, and the pressure applied in the film thickness direction of the electrolyte membrane 80 is adjusted. The deformation of the electrolyte membrane 80 in the film thickness direction can be prevented, and a more reliable measurement result can be obtained.

  A steam channel 53 communicating with the through hole 51 is formed at a portion where the steam channel grooves 52 provided in the first and second measuring jigs 11 and 12 face each other.

  Referring to FIGS. 10A and 10B, the first and second ammeter electrodes 21 and 22 are connected to the current system terminal 8 provided in the measuring instrument 6. Similarly, the first and second voltmeter electrodes 31 and 32 are connected to the voltage system terminal 9 provided in the measuring instrument 6 (see FIG. 1). The first and second measuring jigs 11 and 21 are disposed in a constant temperature and humidity chamber.

  A current is applied to the electrolyte membrane 80 via the first and second ammeter electrodes 21 and 22. The potential difference in the film thickness direction of the electrolyte membrane 80 is measured by the first and second voltmeter electrodes 31 and 32. The ion conductivity in the film thickness direction of the electrolyte membrane 80 is determined based on the measurement result, and the result is obtained.

  During the measurement, water vapor v is supplied to the electrolyte membrane 80 through the through holes 51 provided in the first and second measuring jigs 11 and 12. The humidity and temperature conditions around the measurement site 81 are managed.

  The steam channel 53 makes it possible to sufficiently distribute the water vapor v around the measurement site 81. This makes it possible to accurately manage the humidity and temperature state at the measurement site 81 and to measure ion conductivity simulating the set measurement environment.

  As described above, in the present embodiment, the first and second voltmeter electrodes 31, 32, the first and second external electrodes are disposed between the first and second ammeter electrodes 21, 22. The membranes 41 and 42 and the electrolyte membrane 80 are arranged so as to overlap each other, and the electrolyte membrane 80 and the four measurement electrodes are connected by a simple operation of sandwiching them between the first and second measurement jigs 11 and 12. Can be electrically connected. For this reason, when measuring the ion conductivity in the film thickness direction by the four-terminal method, the work efficiency of the connection work can be improved. The first and second measuring jigs 11 and 21 and other members required for measurement can be shared for different electrolyte membranes 80. Therefore, in the case of repeated use, the material cost required for measurement can be reduced.

  Water vapor v can be supplied to the electrolyte membrane 80 through the through holes 51 provided in the first and second measuring jigs 11 and 12. It is possible to manage the humidity and temperature conditions around the measurement site 81 sandwiched between the first ammeter electrode 21 and the second ammeter electrode 22. The steam channel 53 makes it possible to sufficiently distribute the water vapor v around the measurement site 81. The humidity and temperature state in the measurement site 81 can be managed with high accuracy.

  The first and second ammeter electrodes 21, 22 have a first electrode portion 25 formed in a planar shape extending in the surface direction of the electrolyte membrane 80. The contact area with the electrolyte membrane 80 can be increased, and the electrical connection between the electrolyte membrane 80 and the first and second ammeter electrodes 21 and 22 can be stably maintained. Variations in measurement results can be prevented, and more reliable measurement results can be obtained.

  As the first and second voltmeter electrodes 31 and 32, conductive electrode wires are used. The formation of the coating film on the electrode wire is omitted, and the material cost is reduced. Since thin electrode wires are used for the first and second voltmeter electrodes 31 and 32, the area of the portion where the first and second voltmeter electrodes 31 and 32 are in contact with each other is reduced. Can do. The difference between the thickness t1 of the electrolyte membrane 80 and the distance d between the first and second voltmeter electrodes 31 and 32 can be reduced, and a more reliable measurement result can be obtained.

  The first and second voltmeter electrodes 31 and 32 are disposed so as to be in point contact with each other with the electrolyte membrane 80 interposed therebetween. When a force is applied to the first and second voltmeter electrodes 31 and 32 in the direction in which the electrolyte membrane 80 is sandwiched, it is possible to relieve the pressure applied to a portion other than the point-contacted portion. become. It is possible to prevent the voltmeter electrodes 31 and 32 from coming into contact with each other in a wide range around the measurement site 81 sandwiched between the first and second voltmeter electrodes 31 and 32, and supply of water vapor v to the measurement site 81 The amount can be increased.

  The first and second outer films 41 and 42 are formed to have an elastic modulus smaller than that of the electrolyte membrane 80. The first and second outer films 41 and 42 are deformed so as to wrap the first and second voltmeter electrodes 31 and 32 in the film thickness direction. Even when the force sandwiched in the film thickness direction is excessively applied, the distance between the first and second voltmeter electrodes 31 and 32 can be prevented from changing.

  The pressure applied in the film thickness direction using the pressurizing means 70 can be adjusted, and the amount of deformation in the film thickness direction of the electrolyte membrane 80 can be adjusted. Thereby, a more reliable measurement result can be acquired.

  The pressurizing means 70 utilizes a screw member 71 and a screw hole 72 for fastening the first and second measuring jigs 11 and 21 in the film thickness direction. By managing the amount of torque, the pressure applied to the electrolyte membrane 80 can be adjusted.

  In the above-described embodiment, the first outer film 41 and the first voltmeter electrode 31 are sequentially stacked on the first measurement jig 11. Can be prepared in a state of being fixed to the first measuring jig 11. Similarly, the electrical connection can be performed by a simple operation of simply sandwiching the electrolyte membrane 80 with the second measurement jig 21 prepared in advance.

  The pressurizing means 70 uses the screw member 71 and the screw hole 72 and tightens the first and second measuring jigs 11 and 12 to adjust the pressure. However, the pressurizing means 70 is limited to such a configuration. Is not to be done. For example, it is possible to use a pressure regulator or the like that applies pressure to the first and second measuring jigs 11 and 12 in a direction facing each other.

  In the embodiment, the measurement apparatus and the measurement method of the present invention are applied to the measurement of ion conductivity in the film thickness direction of a thin film electrolyte membrane used in a polymer electrolyte fuel cell. However, the present invention is not limited to this, and can be widely applied to other electrolyte membranes that can be measured for ion conductivity.

(Example)
Embodiments of the present invention will be specifically described below based on examples. In addition, this invention is not limited only to these Examples, It can change suitably.

  In this example, the measurement of electrical conductivity in the film thickness direction of the electrolyte membrane 80 was performed using the ion conductivity measuring device 5 described above. The implementation conditions are as follows.

  The electrolyte membrane 80 is installed on the first and second measuring jigs 11 and 12, and the first and second ammeter electrodes 21 and 22 and the first and second voltmeter electrodes 31 and 32 are provided. Utilizing the four-terminal method, measurements were made. After the electrolyte membrane 80 is installed, the first and second measuring jigs 11 and 12 are placed in a thermo-hygrostat (manufactured by Enomoto Kasei Co., Ltd., ETAC HIFLEX-FX407P type), and around the measurement site 81 The environment was maintained at a room temperature of 80 ° C. and a relative humidity of 30%. For the measuring instrument 6, an impedance analyzer (manufactured by Solartron, model 1260) was used.

As the electrolyte membrane 80, the following four types of random copolymers or block copolymers were produced according to the method described in the technical literature (Polymer 49, pp. 715-723 (2008)), and used as sample membranes.
(1) Random copolymer (denoted as “random”).
(2) A block copolymer having a block length of 3 kg / mol (denoted as “3k”).
(3) A block copolymer having a block length of 7 kg / mol (denoted as “7k”).
(4) A block copolymer having a block length of 10 kg / mol (denoted as “10k”).

  As the first and second outer films 41 and 42, NR211 films (manufactured by DuPont) were used.

  In FIG. 11, the electrical conductivity in the film thickness direction of the electrolyte membrane 80 obtained by measurement is shown. In the figure, the conductivity in the film surface direction of the electrolyte membrane 80 measured by the existing measuring method by the four-terminal method is also shown. In addition, since the ionic conductivity is a value that increases in proportion to the electrical conductivity, the electrical conductivity indicated by the measurement result is a standard indicating the magnitude relationship of the ionic conductivity. In addition, the conductivity also serves as an indication of the power generation performance when the electrolyte membrane 80 is used for MEA (membrane electrode assembly).

  In the measurement of the conductivity in the film thickness direction, when block copolymers are compared with each other, it can be confirmed that 7k is the maximum and decreases in the order of 3k and 10k. On the other hand, in the measurement of the conductivity in the film surface direction, it can be confirmed that 7k is the maximum and decreases in the order of 10k and 3k.

In FIG. 12, as a reference example, GDE (gas diffusion electrode with a catalyst layer, manufactured by Johnson Matthey Fuel Cell) is hot-pressed on each of the above electrolyte membranes 80 to form MEA (at 130 ° C. under 4 MPa under 10 MPa). Shows the power generation performance of Each MEA was subjected to a power generation performance evaluation test (in a 100% humidified gas (H ₂ / O ₂ ) atmosphere, the cell temperature was 80 ° C.).

  Comparing the block copolymers, it can be confirmed that the MEA using the 7-k electrolyte membrane 80 has the best power generation performance, and then decreases in the order of 3k and 10k. It can be confirmed that the measurement results in the film thickness direction of the electrolyte membrane 80 described above coincide with the measurement results in the film surface direction. From this result, it is possible to obtain a more reliable measurement result when the ionic conductivity of the electrolyte membrane 80 is measured in the film thickness direction than when measured in the film surface direction. I can confirm.

  The electrolyte membrane 80 may have material anisotropy in the film surface direction at the stage of manufacture. For this reason, when the ionic conductivity of the electrolyte membrane 80 is measured in the film surface direction, a measurement result with low reliability may be obtained. In the measurement of ion conductivity in the film thickness direction using the ion conductivity measuring device 5, it becomes possible to properly reflect the influence of material anisotropy, and to obtain a more reliable measurement result. The effect that it can be acquired was confirmed.

5 Ion conductivity measuring device,
6 Measuring instruments,
7 Electrode cable,
8 Terminal for current system,
9 Terminal for voltage system,
11 First measuring jig,
12 Second measuring jig,
13 1st jig | tool component piece,
14 Second jig component piece,
15 locating pin,
16 Groove for current electrode,
17 flat part,
18 inclined surface,
19 Groove for voltage electrode,
21 First ammeter electrode;
22 Second ammeter electrode,
25 1st electrode part,
26 second electrode part,
27 Convex,
31 First voltmeter electrode,
32 Second voltmeter electrode,
41 first outer membrane,
42 second outer membrane,
51 through holes,
52 Groove for steam flow path,
53 Steam flow path,
70 pressure means,
71 Screw member (fastening means),
72 screw holes,
73 Positioning hole,
74 connecting end face,
80 electrolyte membrane,
81 measurement site,
v water vapor,
t1 film thickness dimension,
w The width of the membrane,
d Distance between electrodes.

Claims (9)

An ionic conductivity measuring device that measures the ionic conductivity in the film thickness direction of an electrolyte membrane by a four-terminal method,
A first measuring jig in which a first ammeter electrode is disposed in contact with the electrolyte membrane via a conductive first outer membrane;
A second measuring jig in which a second ammeter electrode is disposed in contact with the electrolyte membrane via a conductive second outer membrane;
A first voltmeter electrode disposed between the electrolyte membrane and the first outer membrane;
A second voltmeter electrode disposed between the electrolyte membrane and the second outer membrane,
By disposing the first and second measuring jigs so as to sandwich the electrolyte membrane in the film thickness direction between the first ammeter electrode and the second ammeter electrode, An apparatus for measuring ion conductivity, wherein the first and second ammeter electrodes and the first and second voltmeter electrodes are electrically connected to an electrolyte membrane, respectively. The first and second measuring jigs include a through hole for supplying water vapor to the electrolyte membrane,
The ion conductivity measuring device according to claim 1, further comprising: a groove portion that forms a vapor flow path that communicates with the through hole around the electrolyte membrane.   3. The ion conductivity measuring device according to claim 1, wherein the first and second ammeter electrodes have a planar shape extending in a surface direction of the electrolyte membrane. 4.   The ion conductivity measuring device according to any one of claims 1 to 3, wherein the first and second voltmeter electrodes are made of conductive electrode wires having no coating film.   5. The ion conductivity measuring device according to claim 4, wherein the first and second voltmeter electrodes are arranged so as to cross each other so as to be in point contact with each other with the electrolyte membrane interposed therebetween.   The ionic conductivity measuring device according to any one of claims 1 to 5, wherein the first and second outer membranes have an elastic modulus smaller than an elastic modulus of the electrolyte membrane.   The ion conductivity measuring device according to claim 1, further comprising a pressurizing unit that applies pressure to the film thickness direction of the electrolyte membrane.   The said pressurization means is an ion conductivity measuring apparatus of Claim 7 which clamps the said 1st and 2nd measuring jig with a fastening means, and provides a pressure. An ion conductivity measurement method for measuring ion conductivity in the film thickness direction of an electrolyte membrane by a four-terminal method,
The electrolyte membrane is sandwiched in the film thickness direction by the first ammeter electrode disposed on the first measurement jig and the second ammeter electrode disposed on the second measurement jig. The first and second measuring jigs are arranged in such a manner that the first and second ammeter electrodes are respectively connected to the electrolyte membrane via conductive first and second outer membranes. And electrically connecting the first and second voltmeter electrodes disposed between the electrolyte membrane and each of the first and second outer membranes to the electrolyte membrane. Ion conductivity measurement method for connection.

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