JP2008192571A - Measuring device for physical property of diffusion layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a measuring device for the physical property of a diffusion layer capable of measuring two or more physical properties of a diffusion layer in continuous processes using one measuring device. <P>SOLUTION: The measuring device A for a physical property of a diffusion layer comprises a lower disk 10 and upper disk 30, in which zones coming in contact with the diffusion layer P are set up to be nonconductive, capable of airtightly sandwiching a diffusion layer P, a weighing means for weighing weight of the diffusion layer p mounted on the lower disk 10, a gap measuring means for measuring a gap between the lower disk 10 and upper disk 30, an air permeability measuring means for supplying a gas for measuring to the sandwiched diffusion layer P and measuring air permeability of the diffusion layer P by measuring back pressure of the supplied gas, and a contact resistance measuring means for measuring contact resistance on the surface of the diffusion layer by applying voltage on the surface of the sandwiched diffusion layer P. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for measuring various physical properties of a diffusion layer used in a membrane electrode assembly constituting a fuel cell.

  For example, in a polymer electrolyte fuel cell, as shown in FIG. 3, an electrode (MEA: Membrane-Electrode Assembly) 3 comprising an electrolyte membrane 1 and electrode catalyst layers 2 and 2 applied to the front and back surfaces thereof is used. The electrode 3 forms a fluid flow path 5 for supplying a fuel gas (hydrogen) and an oxidizing gas (oxygen, usually air) through the diffusion layers 4 and 4 and functions as a current collector 6. To be unit cell A. The diffusion layer 4 is for efficiently diffusing the fuel gas and the oxidizing gas, and carbon cloth, carbon paper, or the like is used.

  As described above, the fuel cell or its unit cell is configured by organically combining a plurality of members such as the electrolyte membrane 1, the electrode catalyst layer 2, the diffusion layer 4, and the separator 6, and discharge (power generation) thereof. The quality of performance may be attributed to a combination state thereof, or may be attributed to individual component members themselves. If objective performance evaluation can be performed individually for each component member, the obtained data will be extremely effective for designing an efficient fuel cell (unit cell).

  From such a point of view, Patent Documents 1 and 2 particularly focus on the diffusion layer among the individual members constituting the fuel cell and evaluate the performance of the diffusion layer in terms of air permeability (air permeability). A performance evaluation apparatus that can be performed alone is described.

JP 2004-363041 A Japanese Patent Laid-Open No. 2004-178881

  In order to obtain an efficient fuel cell (unit cell), it is effective to acquire data on the air permeability of the diffusion layer used therein, but the thickness and weight of the diffusion layer, and further, the separator or catalyst layer It is also valid and necessary to obtain objective data on other physical property values such as contact resistance values at the contact surface. Currently, to obtain various physical property values of the diffusion layer, an apparatus as described in Patent Document 1 or 2 is used for air permeability, and for measuring thickness, weighing, contact resistance, etc., respectively. Dedicated measurements are used. That is, in order to obtain various physical property values necessary for one diffusion layer, another type of measuring device is used and a lot of work time is required.

  The present invention has been made in view of the circumstances as described above, and it is possible to measure a physical property value of a diffusion layer that enables measurement of two or more physical property values of the diffusion layer by a continuous process with a single measuring device. It is an object to provide an apparatus.

  A diffusion layer property value measuring device according to the present invention is a device for measuring two or more property values of a diffusion layer, and can hermetically sandwich a diffusion layer as a measured object and at least comes into contact with the diffusion layer. The region includes a lower plate and an upper plate made non-conductive, and further includes a weighing means for measuring the weight of the diffusion layer placed on the lower plate, and a space between the lower plate and the upper plate. A gap measuring means for measuring the gap between the lower plate and the upper plate, measuring gas is supplied to the diffusion layer sandwiched between the lower plate and the back pressure of the supplied gas to measure the air permeability of the diffusion layer Air permeability measuring means for measuring the pressure, and contact resistance measuring means for measuring the contact resistance of the surface of the diffusion layer by applying a voltage to the surface of the diffusion layer sandwiched between the lower plate and the upper plate. It is characterized by.

  In the above measurement apparatus, two or more physical property values of the diffusion layer can be measured by going through a series of processes. In the measurement, the lower board and the upper board are separated from each other, and a diffusion layer as a measurement object is set in a non-conductive region of the lower board. The lower board is provided with weighing means such as an electromagnetic force balance type weighing machine, and the diffusion layer is weighed. Next, or during weighing, both or either of the lower board and the upper board are moved, and the diffusion layer is hermetically sandwiched between the two boards. When the clamping state is finished, the gap between the lower board and the upper board is measured by the gap measuring means. This measured value is the thickness of the diffusion layer. By changing the travel distance of the panel, the thickness of the diffusion layer in the uncompressed state can also be measured, and the thickness of the diffusion layer in a state compressed to some extent as in an actual fuel cell can also be measured. . A means such as a dial gauge can be adopted as the gap measuring means.

  In order to measure the air permeability of the diffusion layer, an air permeability measuring means is used. That is, after the diffusion layer is sandwiched between the lower plate and the upper plate in an airtight state, the gas for measurement is supplied to the sandwiched diffusion layer by the air permeability measurement means, and the back pressure or back of the supplied gas is supplied. Measure the change in pressure. More specifically, the air permeability measuring means can measure both in-plane air permeability and normal air permeability of the diffusion layer sandwiched between the lower plate and the upper plate in an airtight state. One of the lower board and the upper board is provided with a measurement gas supply unit, and both the lower board and the upper board are provided with exhaust parts.

  The measurement gas supply unit is connected to a pressurized gas supply source, and a measurement gas having a constant pressure is supplied from one surface of the diffusion layer sandwiched in an airtight state. The supplied measurement gas passes through the diffusion tank and is preferably discharged from an exhaust section opened to the atmosphere side. Since the back pressure of the supplied gas changes according to the gas permeability of the diffusion layer, the gas permeability of the diffusion layer can be measured by measuring the gas back pressure. The air permeability in the normal direction can be measured by closing the exhaust part on the side where the measurement gas supply part is provided and opening only the exhaust part formed on the opposing board, and the measurement gas supply part is provided The air permeability in the in-plane direction can be measured by opening the exhaust part on the side and closing the exhaust part formed on the opposing board.

  For measuring the contact resistance on the surface of the diffusion layer, it is used as a contact resistance measuring means. That is, a voltage is applied to the surface of the diffusion layer sandwiched between the lower plate and the upper plate, and the surface of the diffusion layer is expressed by the formula: (voltage) / (current) × (electrode length) / (electrode interval). Measure the contact resistance. In a more preferred aspect, each of the lower board and the upper board is provided with a pair of electrodes so that the contact resistance on the upper surface side and the lower surface side of the diffusion layer sandwiched between the lower board and the upper board can be measured simultaneously. Like that.

  Note that either the air permeability measurement or the contact resistance measurement may be performed first. In addition, it is not necessary to perform all of the above measurement items, and among the plurality of physical property values of the diffusion layer that is the object to be measured, only one of the physical property values required at that time is measured. The value measuring device may be operated.

  By using the diffusion layer property value measuring apparatus according to the present invention, it is possible to measure two or more property values of a diffusion layer used in a fuel cell without a series of processes, and it is possible to speed up the property value measurement. It becomes.

  Hereinafter, an embodiment of a diffusion layer physical property measuring apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view thereof, and FIG. 2 is a schematic view of a region where the electrolyte membrane is in contact with the lower plate and the upper plate of the apparatus.

  In this example, the diffusion layer property value measuring apparatus A includes a lower board 10 and an upper board 30. A column 11 extending in the vertical direction is attached to the lower plate 10, and a box 12 is fixed to the column 11 at a predetermined height from the lower plate 10. In the box 12, such as a dial gauge that can measure the distance that the piston 14 of the air cylinder device 13 moves and the air cylinder device 13 whose operating direction is perpendicular to the lower plate 10. A distance measuring means (not shown) is internally provided. The upper board 30 is attached to the tip of the piston 14.

  The lower board 10 has a mounting plate 15 having a diffusion layer P on the upper surface side, and at least the upper surface side of the mounting plate 15 is made of a non-conductive material (for example, Teflon coating). Although not shown, weighing means such as an electromagnetic force balance type weighing machine capable of weighing the diffusion layer P placed on the placing plate 15 is attached to the lower plate 10 or the placing plate 15.

  FIG. 2 a is a view from above the mounting plate 15, and an O-ring 16 is attached to the entire periphery in the vicinity of the outer edge. A first measurement gas discharge port 17 is also formed on the inner side of the entire circumference, and a measurement gas filling port 18 is also formed on the inner side of the first measurement gas discharge port 17. As shown in FIG. 1, the first measurement gas discharge port 17 communicates with a gas outlet 19 opened to the atmosphere, and the measurement gas filling port 18 is connected to a measurement gas source (not shown) having a predetermined pressure. Connected to the pressurized gas inlet 20 to be connected. A gas pressure measuring device 22 is attached to a pipe line 21 extending from the pressurized gas inlet 20 to the measurement gas filling port 18. Further, an opening / closing shutter (not shown) operated by a control mechanism (not shown) is attached to the first measurement gas discharge port 17.

  An anode electrode 23 and a cathode electrode 24 are attached to the surface in the region surrounded by the measurement gas sealing port 18 of the mounting plate 15 so as to face each other. As shown in FIG. The cathode electrode 24 is connected to a power source 25.

  The upper board 30 has a contact plate 31 that can be in close contact with the diffusion layer P placed on the mounting plate 15 of the lower board 10 on the lower surface side. At least the upper surface side of the contact plate 31 is made of a non-conductive material (for example, Teflon coating) in the same manner as the mounting plate 15 described above.

  FIG. 2B is a view of the contact plate 31 as viewed from below, and a second measurement gas discharge port is provided at a position facing the first measurement gas discharge port 17 formed in the mounting plate 15 in the vicinity of the outer edge thereof. 32 is formed. As shown in FIG. 1, the second measurement gas discharge port 32 communicates with a gas outlet 33 that opens to the atmosphere. Further, an anode electrode 34 and a cathode electrode 35 are attached at positions facing the anode electrode 23 and the cathode electrode 24 attached to the mounting plate 15 on the surface of the contact plate 31, and the two electrodes are connected to a power source 36. is doing.

  An example of the usage mode (measurement mode of various physical property values of the diffusion layer) of the diffusion layer physical property value measuring apparatus A will be described. At the start of measurement, a control device (not shown) is operated to operate the air cylinder device 13 to widen the distance between the lower board 10 and the upper board 30 and to set the distance between the lower board 10 and the upper board 30 in the control apparatus. Store in the memory. In this state, the diffusion layer P that is the object to be measured is placed on the mounting plate 15 of the lower panel 10. The weighing means measures the weight of the placed diffusion layer P and stores it in the memory in the control device.

  Again, the air cylinder device 13 is operated to bring the upper plate 30 closer to the lower plate 10, and the contact plate 31 provided on the upper plate 30 is in close contact with the upper surface of the diffusion layer P placed on the placement plate 15. To do. In this state, the O-ring 16 acts and the diffusion layer P is in a state in which the upper board 30 is airtightly sandwiched between the lower boards 10. Further, the distance from the initial state to the close contact with the diffusion layer P is measured by the distance measuring means, and the value is sent to the control device. The control device takes the difference between the initial value stored in the memory and the moving distance, thereby determining the gap between the mounting plate 15 and the contact plate 31 in that state, that is, the thickness of the diffusion layer P. Calculate and store the value in memory.

  In measuring the air permeability, the controller is operated to send the pressurized measurement gas from the pressurized gas inlet 20 through the conduit 21 to the measurement gas filling port 18 formed in the mounting plate 15. Initially, both the opening and closing shutters attached to the first measurement gas discharge port 17 and the second measurement gas discharge port 32 are closed. In this state, the reading value of the gas pressure measuring device 22 attached to the pipe line 21 is stored in the memory of the control device. Thereafter, when only the open / close shutter on the first measurement gas discharge port 17 side is opened, the measurement gas supplied from the measurement gas filling port 18 moves in the in-plane direction within the diffusion layer P, and the first measurement gas is supplied. The gas is discharged from the discharge port 17 to the atmosphere. The reading value (i.e., back pressure) of the gas pressure measuring device 22 when the measurement gas is discharged is sent to the control device. The control device calculates the difference between the original reading value stored in the memory and the reading value sent in, calculates the air permeability in the in-plane direction of the diffusion layer P based on this value, and stores it in the memory.

  Next, the open / close shutter on the first measurement gas discharge port 17 side is closed, and the open / close shutter on the second measurement gas discharge port 32 side is opened. Thereby, the measurement gas supplied from the measurement gas filling port 18 moves in the normal direction in the diffusion layer P and is discharged from the second measurement gas discharge port 32 to the atmosphere. From the reading value (ie, back pressure) of the gas pressure measuring device 22 when the measurement gas is discharged, the control device calculates the air permeability in the normal direction of the diffusion layer P and stores the memory in the same manner as described above. To store.

  In measuring the contact resistance of the diffusion layer P, power is supplied from the power source 25 to the electrodes 23 and 24, and power is supplied from the power source 36 to the electrodes 34 and 35. When it is desired to measure only the contact resistance of one surface of the diffusion layer P, power is supplied only to the electrode corresponding to that surface. Based on the value of the current flowing between the electrodes facing each other and the voltage of the power supply, the control device calculates the contact resistance of one or both surfaces of the diffusion layer P and stores the value in the memory.

  The user of the apparatus A can simultaneously obtain a plurality of physical property values of the diffusion layer P that is the object to be measured by taking out a desired calculated value from the memory. The measured diffusion layer P is taken out from the device A, a new diffusion layer is set again, the same operation is repeated, and the calculation results are stored in the memory. It can also be recognized and analyzed as a group.

1 is a schematic side view of an embodiment of a diffusion layer property value measuring apparatus according to the present invention. FIG. 2 is a schematic view of a region where the electrolyte membrane is in contact with the lower board and the upper board in the apparatus shown in FIG. 1, FIG. 2 a shows the lower board side and FIG. Schematic for demonstrating a fuel cell (unit cell).

Explanation of symbols

  A ... Diffusion layer property value measuring device, P ... Diffusion layer, 10 ... Lower panel, 11 ... Column, 12 ... Box, 13 ... Air cylinder device, 14 ... Piston, 15 ... Mounting plate, 16 ... O-ring, 17 DESCRIPTION OF SYMBOLS 1st measurement gas discharge port, 18 ... Measurement gas filling port, 19 ... Gas outlet opened to air | atmosphere, 20 ... Pressurized gas inlet, 21 ... Pipe line, 22 ... Gas pressure measuring device, 23 ... Anode electrode, 24 ... Cathode electrode, 25 ... Power source, 30 ... Upper panel, 31 ... Close contact plate, 32 ... Second measurement gas discharge port, 33 ... Gas outlet opening to the atmosphere, 34 ... Anode electrode, 35 ... Cathode electrode, 36 ... Power source

Claims (3)

An apparatus for measuring two or more physical property values of a diffusion layer,
A diffusion layer that is a measurement object can be hermetically sandwiched, and at least a region in contact with the diffusion layer includes a lower board and an upper board that are non-conductive, and
Weighing means for measuring the weight of the diffusion layer placed on the lower plate,
A gap measuring means for measuring a gap between the lower board and the upper board;
An air permeability measuring means for supplying a measurement gas to the diffusion layer sandwiched between the lower plate and the upper plate and measuring the air pressure of the diffusion layer by measuring the back pressure of the supplied gas; ,
Contact resistance measuring means for measuring the contact resistance of the surface of the diffusion layer by applying a voltage to the surface of the diffusion layer sandwiched between the lower plate and the upper plate;
A device for measuring physical property values of a diffusion layer, comprising:   The air permeability measuring means can measure both the in-plane air permeability and the normal air permeability of the diffusion layer sandwiched between the lower board and the upper board. 2. The diffusion layer property value measuring apparatus according to claim 1, further comprising a measurement gas supply unit on one of them, and an exhaust unit on both of the lower plate and the upper plate.   The contact resistance measuring means has a pair of electrodes on each of the lower board and the upper board so that the contact resistance on the upper surface side and the lower surface side of the diffusion layer sandwiched between the lower board and the upper board can be measured simultaneously. The device for measuring a physical property value of a diffusion layer according to claim 1 or 2, comprising:

Images