JP2008027902A - Inspection method and device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method and device of a fuel cell in which a renewed attention is paid to a corresponding relation between cell characteristics and thermal conductivity of the fuel cell and characteristic evaluation of the fuel cell is simplified. <P>SOLUTION: Thermal diffusion factors of composing members of a fuel cell such as unit cells 20, an MEA 21 composing the above unit cells, gas diffusion member 33 or the like are measured during a manufacturing process of a fuel cell. In the measuring method, a transmission of heat raised from a periodic heat generation by angular frequency ω in an exothermic body 212 is detected by an infrared detecting unit housed in a temperature detecting unit 214, and a phase differential of a temperature modulation and a detected temperature at a time of heating is obtained, and based on the above, thermal diffusion factors are measured for a plurality of measuring positions. A judgement of bonding of composing members is made based on the obtained thermal diffusion factors and cell characteristics of the unit cell is evaluated based on a differential of thermal diffusion factors. For the above, a map memorized by a momory part 224 is used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell inspection method and apparatus having a layer structure in which an electrolyte is sandwiched between a pair of electrodes.

  The fuel cell includes a layer structure in which an electrolyte is sandwiched between a pair of electrodes, and a plurality of battery structures including the layer structure are stacked as a unit. Therefore, characteristics such as the power generation capability of the fuel cell depend on the characteristics of the individual battery constituent units, and thus it is desired to evaluate the characteristics of the battery constituent units.

  In each battery, an electrolyte is bonded to the electrode on both sides, and a gas supply layer for gas diffusion / supply to the electrode is also bonded to the electrode. And since the characteristics of each battery depend on the joining situation between these members (for example, the quality of joining, the peel strength that defines the joining property, etc.), the joining situation between members by measuring some physical phenomenon If it can be determined, it may be possible to evaluate the battery characteristics.

  As a technique for determining the joining state between such members, there are the following patent documents. According to this patent document, in determining non-destructiveness of the bondability between the cylinder head and the valve seat, one of the members to be joined is heated at a predetermined temperature, and the transmitted heat transmitted to the other member to be joined is measured. And the joining condition (goodness of joining property) of the cylinder head which is a member to be joined, and a valve seat is judged from the value of the measured temperature and the state of temperature rise.

JP-A-9-96204

  The method for determining the joining state according to the above-mentioned patent document has been expected to be applied to a battery configuration. However, the following problems have been pointed out, and the practical situation has not been reached. The electrolyte, electrode, or gas supply layer, which is a battery bonding target member, differs from the metal or alloy, which is the material of the cylinder head or valve seat, in its composition and structure. In addition, since the influence of heat radiation to the surroundings is large, it is difficult to evaluate the absolute value of heat. Therefore, even if the joining state of the joining target members in the fuel cell is determined according to the method of Patent Document 1, a phenomenon occurs in which the measured temperature value is different at the measurement location even though it is the same battery. The determination of the joining state of the members lacked reliability. For this reason, the reliability of the characteristic evaluation of the battery constituent unit formed by joining the members such as the electrolyte, the electrode, or the gas supply layer, and the fuel cell as a whole, is low. In addition, since the electrolyte and the electrode are joined over the electrode area, and the electrode and the gas supply layer are joined, there is a possibility that the joining state at each joint location may be non-uniform. In particular, since a high output battery requires a wide electrode area, the joining range of the electrolyte, the electrode, and the gas supply layer is also widened. Therefore, the non-uniformity of the thermal conductivity characteristics of the members to be joined and the non-uniformity of the joining situation can cause a large difference in the measured temperature value at each measurement location. There remains room for improvement in the reliability of the determination and the reliability of the characteristics evaluation of the fuel cell based on this determination.

  The present invention has been made to solve the above-mentioned problems, and its object is to provide a new technique capable of improving the reliability of the determination of the joining state of the constituent members of the fuel cell, and hence the reliability of the characteristic evaluation. To do.

  In order to achieve at least a part of the above object, the present invention adopts the following configuration.

[Application 1: Inspection method of fuel cell]
A method for inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
When heating the layer structure from one side of the front and back surfaces of the layer structure, the layer structure is heated while performing temperature modulation at a predetermined frequency, and the heating is performed over the heating region on the one surface. Inducing a temperature modulation on the one side of the layer structure,
The temperature modulation of heat transmitted in the thickness direction of the layer structure is measured at a plurality of measurement points included in the measurement area on the other surface side of the layer structure facing the heating area,
Obtaining a phase difference between the measured temperature modulation and the temperature modulation when the layer structure is heated from the one surface side for each of the plurality of measurement points;
Based on the phase difference obtained for each measurement location, obtain the thermal conductivity characteristics of the fuel cell in the layer direction for each measurement location of the layer structure,
The gist is to determine the joining state of the constituent materials of the layer structure based on the heat conduction characteristics obtained for each measurement location.

  In the fuel cell inspection method described above, when inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes, the layer structure is heated from one side of the front and back surfaces of the layer structure. The layer structure is heated while causing temperature modulation at a predetermined frequency, and temperature modulation is induced on the one surface side of the layer structure over the heating region on the one surface. The heat applied to one side of the layer structure is attenuated in the process of heat propagation in the thickness direction of the layer structure, but the temperature modulation induced on the one side of the layer structure And propagates to the other surface side of the layer structure with a phase delay. This phase delay is determined depending on the heat conduction characteristics of the heat propagation point of the layer structure to be measured, and this heat conduction characteristic is determined by the characteristics of the individual materials of the layer structure, the state of bonding between the materials, As a result, there is a high correlation with the battery characteristics of the fuel cell.

  Based on such knowledge, the layer structure is heated while inducing temperature modulation on one side of the layer structure, and the temperature structure of the heat transmitted through the layer structure in the thickness direction is opposed to the heating region. The phase difference between the temperature modulation measured at a plurality of measurement points included in the measurement region on the other surface side of the body and the temperature modulation when the layer structure is heated from the one surface side. For each of the plurality of measurement points. As described above, the phase difference of such temperature modulation depends on the heat conduction characteristics of the heat propagation point that causes the phase difference (each measurement point). Obtain the heat conduction characteristics of the part. And based on the said heat conduction characteristic calculated | required for every said measurement location, the joining condition of the structural material of the said layer structure is determined.

  In the method for inspecting a fuel cell having the above-described configuration, when determining the joining state of the constituent materials constituting the layer structure of the fuel cell, the temperature modulation for each measurement location is used instead of the measurement temperature value for each measurement location. The heat conduction characteristic based on the phase difference of is used. In this case, the phase difference of the temperature modulation is determined depending on the heat conduction characteristic of the measurement location, and this heat conduction characteristic is related to the state of bonding between the individual constituent materials of the layer structure, and further to the battery characteristics of the fuel cell. Since there is a high correlation, according to the fuel cell inspection method described above, it is possible to improve the reliability of the determination of the joining state of the constituent members of the fuel cell. Moreover, since it is not necessary to put the fuel cell in the operating state when determining the joining state, it is simple. In addition, since the determination of the joining state can be performed in the process of manufacturing the fuel cell, the quality of the layer structure and the fuel cell (cell) can be determined based on this evaluation, which can contribute to quality improvement.

  Furthermore, as described above, the heat conduction characteristics are highly correlated not only with the state of joining of the constituent members of the layer structure but also with the battery characteristics of the fuel cell. The battery characteristics of the fuel cell can also be evaluated based on the characteristic deviation and the characteristic correspondence in which the deviation is associated with the battery characteristic of the fuel cell. Further, the battery characteristics of the fuel cell can be evaluated based on the determined joining state and a characteristic correspondence in which the determined state is associated with the battery characteristic of the fuel cell. In this way, the reliability of the fuel cell characteristic evaluation can be improved, and the characteristic evaluation is simple because it is not necessary to put the fuel cell in an operating state.

[Application 2: Other inspection methods for fuel cells]
A method for inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
When heating the layer structure from one side of the front and back surfaces of the layer structure, the layer structure is heated while causing temperature modulation at a predetermined frequency, and the one of the layer structures is heated at the heating location. Induces temperature modulation on the side of the surface,
The temperature modulation of the heat transmitted in the thickness direction of the layer structure is measured at a measurement location on the other surface side of the layer configuration facing the heating location,
Obtaining a phase difference between the measured temperature modulation and the temperature modulation when the layer structure is heated at the heating portion on the one surface;
Based on the obtained phase difference, obtain the heat conduction characteristics of the fuel cell in the layer direction at the measurement location of the layer structure,
While changing the heating location and the measurement location in the layer structure, and determining the phase difference at a plurality of locations of the layer structure, the heat conduction characteristics based on the phase difference is determined at a plurality of locations,
The gist is to determine the joining state of the constituent materials of the layer structure based on the heat conduction characteristics obtained at the plurality of locations.

  In the other inspection method for a fuel cell described above, in inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes, the layer structure is heated from one side of the front and back surfaces of the layer structure. In doing so, the layer structure is heated while causing temperature modulation at a predetermined frequency, and temperature modulation is induced on the one surface side of the layer structure at the heating location, and the layer structure is moved in the thickness direction. The temperature modulation of the heat transmitted to is measured at a measurement location on the other side of the layer structure opposite to the heating location, and the measured temperature modulation and the layer configuration are heated on the one surface. A phase difference from the temperature modulation at the time of heating at a location is obtained, and based on this phase difference, a heat conduction characteristic of the fuel cell in the layer direction at the measurement location of the layer structure is obtained. Then, the heating location and the measurement location are changed in the layer structure, and the thermal conductivity characteristics based on the phase difference are obtained at a plurality of locations while the phase difference is obtained at a plurality of locations in the layer configuration. Ask. And based on the said heat conduction characteristic calculated | required for every said measurement location, the joining condition of the structural material of the said layer structure is determined. Also by this inspection method, the above-described effects such as improvement in reliability of determination of the joining state of the constituent members of the fuel cell can be achieved. Then, based on the deviation of the heat conduction characteristic obtained at a plurality of locations and the characteristic correspondence in which the deviation is associated with the battery characteristic of the fuel cell, or the determined joining situation and the judging situation If the cell characteristic of the fuel cell is evaluated based on the characteristic correspondence associated with the cell characteristic of the fuel cell, the reliability of the characteristic evaluation can be improved.

  In the fuel cell bonding inspection described above, when inducing the temperature modulation, a fuel gas supply layer that receives a supply of the fuel gas of the conductive type of the electrolyte in the layer structure and sends the gas to one of the electrodes; A gas supply layer-containing structure in which the layer structure is joined and sandwiched by an oxidizing gas supply layer that receives supply of an oxidizing gas containing a substance that contributes to oxidation of the conductive species and sends the gas to the other electrode When measuring the temperature modulation, the gas supply layer-containing structure is heated to induce the temperature modulation while causing the temperature modulation from the front and back surfaces of the gas supply layer-containing structure. Can measure the temperature modulation of the heat transmitted through the gas supply layer-containing structure in the thickness direction on the other surface side of the gas supply layer-containing structure. In this way, it is possible to easily measure the thermal conductivity characteristics of the unit structure in which the fuel gas supply layer and the oxidizing gas supply layer are joined and sandwiched between the layer structure in which the electrolyte is sandwiched between the pair of electrodes. It is possible to perform the determination of the joining state of the constituent materials in the constituent unit having the supply layer and the evaluation of the cell characteristics of the fuel cell with high reliability.

  Moreover, when measuring the said temperature modulation, the temperature measurement apparatus which measures the temperature of a measurement object non-contactingly can be used. The temperature measuring device includes an infrared camera that receives infrared rays, and receives infrared rays emitted from a measurement object at the focal position of the camera by the infrared camera, and non-contacts the temperature of the measurement object at the focal position. To measure. And in measuring temperature modulation using this temperature measuring device, the focal position of the infrared camera of the temperature measuring device is in the thickness direction of the layer structure or the gas supply layer containing structure that is the measurement object. While changing, it is also possible to measure the temperature modulation at a position matching the focal position.

  In this way, the layer structure in which the electrolyte is sandwiched between the pair of electrodes, or the gas supply layer-containing structure in which the fuel gas supply layer and the oxidizing gas supply layer are joined and sandwiched between the layer structures are different in the thickness direction. It is possible to easily measure the heat conduction characteristics at the position. In this case, the layer structure in which the electrolyte is sandwiched between the pair of electrodes and the gas supply layer-containing structure are each a joined body of the constituent members, so by changing the focal position in the thickness direction of the respective constituent members, Thermoelectric characteristics over the thickness direction of the constituent member can be obtained. Further, if the focal position is set to the joining position of the constituent members, the heat conduction characteristics at the joining location can be obtained. In other words, for layered structures and gas supply layer-containing structures that are joined members of structural members, not only the transition of the heat conduction characteristics in the thickness direction of the structural members but also the heat conduction characteristics at the joints of the structural members are included. Therefore, it is possible to further improve the reliability of the above-described determination of the joining state based on the heat conduction characteristics and the evaluation of the battery characteristics of the fuel cell.

  The present invention can be applied to a fuel cell inspection apparatus in addition to the above-described fuel cell inspection method. The fuel cell according to the present invention is classified into various types according to the properties of the electrolyte, and includes a polymer electrolyte fuel cell, a phosphoric acid fuel cell, an alkaline fuel cell, and a carbonate ion that use hydrogen ions as the conductive species. A molten carbonate fuel cell having a conductive species, a solid oxide fuel cell having a conductive species of oxygen ions, and the like are included.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a schematic configuration of a fuel cell to be evaluated in an example. The fuel cell in this example is a polymer electrolyte fuel cell, and has a stack structure in which a plurality of cells (single cell 20) are stacked. The unit cell 20 includes an MEA (Membrane Electrode Assembly) 21 containing an electrolyte, and gas supply layers 22 and 23 that sandwich the MEA 21 from both sides to form a sandwich structure. It is clamped by separators 24 and 25 from both sides.

  The MEA 21 includes an electrolyte layer 30 and a pair of electrodes 31 and 32 formed on both surfaces of the electrolyte layer 30 with the electrolyte layer 30 interposed therebetween. The electrolyte layer 30 is a proton conductive ion exchange membrane formed of a solid polymer material such as a fluorine resin, and exhibits good electrical conductivity in a wet state. In this example, a Nafion membrane (manufactured by DuPont) was used. The electrodes 31 and 32 are porous bodies including a catalyst that promotes an electrochemical reaction, for example, platinum or an alloy made of platinum and another metal, and has gas permeability. Since the MEA 21 has such a configuration, the MEA 21 corresponds to the layer structure in the present application in which the electrolyte layer 30 is sandwiched between the pair of electrodes 31 and 32.

  The gas supply layers 22 and 23 are made of a member having gas permeability and electronic conductivity, and can be formed of, for example, a carbon material such as carbon paper, or a metal member such as foam metal or metal mesh. Such gas supply layers 22 and 23 serve as a flow path for a gas to be subjected to an electrochemical reaction, and supply gas and collect current. Here, the gas supply layer 22 includes a gas diffusion member 33 in contact with the separator 24 and an electrode-side gas diffusion member 34 in contact with the MEA 21. Such a gas supply layer 22 forms a fuel gas flow path in a single cell through which a fuel gas containing hydrogen passes between the MEA 21 and the separator 24 and supplies the gas. The gas supply layer 23 includes a gas diffusion member 35 that contacts the separator 25 and an electrode-side gas diffusion member 36 that contacts the MEA 21. Such a gas supply layer 23 forms a single-cell oxidizing gas flow path through which an oxidizing gas containing oxygen passes between the MEA 21 and the separator 25 and supplies the gas.

  Since the single cell 20 has such a structure of the gas supply layer, the single cell 20 corresponds to the gas supply layer-containing structure in the present invention in which the MEA 21 (layer structure) is sandwiched and joined by the gas supply layers 22 and 23. In this case, in the present embodiment, the gas supply layers 22 and 23 are formed by joining the separator-side gas diffusion member and the electrode-side gas diffusion member, but may be a single gas supply layer.

  Each member described above (electrolyte layer 30, electrodes 31, 32, gas diffusion members 33, 35, electrode side gas diffusion members 34, 36) is individually prepared as shown in the upper part of the figure, and in the manufacturing process described later. In the joining process, joining is performed as shown in the lower part of the figure to form a single cell 20.

  In the gas supply layers 22 and 23, the separator-side gas diffusion members 33 and 35 can be formed of a harder porous body than the electrode-side gas diffusion members 34 and 36. Here, the hardness is not the hardness of the material constituting the gas diffusion member, but the hardness of the entire member, and can be represented by, for example, a compression elastic modulus. This is desirable for maintaining the shape of the single cell 20.

  The separators 24 and 25 are gas-impermeable members formed of a material having electron conductivity, and can be formed of a metal member such as stainless steel or a carbon material, for example. The separators 24 and 25 of the present embodiment are formed in a thin plate shape, and the surfaces in contact with the gas supply layers 22 and 23 are flat surfaces without unevenness. However, the fuel gas channel and the oxidizing gas channel are not provided. It can also be set as the separator which has. In this case, the gas supply layer does not have the role of the single-cell fuel gas flow path or the single-cell oxidizing gas flow path, but only needs to have at least a diffusion role.

In addition, a sealing member such as a gasket is disposed on the outer peripheral portion of the single cell 20 in order to ensure gas sealing performance in the single-cell fuel gas flow path and the single-cell oxidizing gas flow path. A plurality of gas manifolds (not shown) through which fuel gas or oxidizing gas flows are provided on the outer peripheral portion of the single cell 20 in parallel with the stacking direction of the single cells 20. The fuel gas flowing through the fuel gas supply manifold among the plurality of gas manifolds is distributed to each single cell 20 and passes through the fuel gas flow path (gas supply layer 22) in each single cell while being subjected to an electrochemical reaction. Then, the fuel gas discharge manifold collects. Similarly, the oxidizing gas flowing through the oxidizing gas supply manifold is distributed to each single cell 20 and passes through each single cell oxidizing gas flow path (gas supply layer 23) while being subjected to an electrochemical reaction. Collect in the gas exhaust manifold. In FIG. 1, the fuel gas (H ₂ ) in the single-cell fuel gas flow path and the oxidizing gas (O ₂ ) in the single-cell oxidizing gas flow path are shown to flow in parallel. Depending on the arrangement of the gas manifold, the flow may flow in different directions such as facing and orthogonal, in addition to the above-described parallel.

  As the fuel gas supplied to the fuel cell, a hydrogen-rich gas obtained by reforming a hydrocarbon-based fuel may be used, or a high-purity hydrogen gas may be used. For example, air can be used as the oxidizing gas supplied to the fuel cell.

  Although illustration is omitted, in order to adjust the internal temperature of the stack structure, a refrigerant flow path through which the refrigerant passes may be provided between each single cell or every time a predetermined number of single cells are stacked. good. The refrigerant flow path may be provided between the separators 24 provided in one single cell and the separator 25 provided in the other single cell between adjacent single cells.

  The single cell 20 is not limited to the layer configuration shown in FIG. 1, and the MEA 21 is sandwiched between the separators on both sides thereof, and a hydrogen gas or air supply passage is provided on the surface of the MEA 21 in the separator. It can also be configured.

  Next, the manufacturing process of the fuel cell having the above-described configuration, specifically the single cell 20 will be described. FIG. 2 is a process diagram showing a method of manufacturing a fuel cell according to the present embodiment, and FIG. 3 is a schematic diagram of an inspection apparatus that performs characteristic evaluation based on the heat conduction characteristics of each component during battery manufacture.

  As shown in FIG. 2, when manufacturing a fuel cell, first, the members constituting the single cell 20, that is, the electrolyte layer 30, the gas diffusion members 33 to 36, and the separators 24 and 25 are prepared. (Step S100). Thereafter, the electrodes 31 and 32 are formed on the electrolyte layer 30 to produce the MEA 21 (step S110). In order to form the electrodes 31 and 32, for example, carbon powder carrying platinum or an alloy made of platinum and another metal is prepared, and the carbon powder carrying the catalyst is dispersed in a suitable organic solvent, and an electrolyte solution ( For example, a paste may be prepared by adding an appropriate amount of Aldrich Chemical, Nafion Solution). By applying this paste on the electrolyte layer 30 by a method such as screen printing, the electrodes 31 and 32 can be formed. Alternatively, a sheet containing a carbon powder carrying the catalyst is formed into a sheet, and the sheet is pressed onto the electrolyte layer 30 to join the electrodes 31 and 32 to the electrolyte layer 30. Also good. Further, the above paste is applied to a peelable sheet (for example, a Teflon sheet: Teflon is a registered trademark) and dried to prepare an electrode transfer sheet from the paste. Then, the two Teflon sheets are sandwiched between the electrolyte layer 30 so that the electrode transfer sheet is bonded to both sides of the electrolyte layer 30, and after the heat pressing at a predetermined temperature and pressure, the Teflon sheet is peeled off, and the electrode transfer sheet is made into the electrolyte. It can also be transferred and bonded to both sides of the layer 30.

  In the present embodiment, the thermal conductivity characteristics of the MEA 21 thus manufactured and the gas diffusion members 33 to 36 are measured (step S120). As will be described later, the heat conduction characteristics of the MEA 21 and the like are as follows. The bonding state of the constituent materials in the MEA 21 and the single cell 20 (the bonding state of the electrolyte layer 30 and the electrodes 31, 32, the bonding state of the MEA 21 and the gas diffusion members 33 to 36). Or the cell characteristics evaluation of the single cell 20 and thus the fuel cell. The heat conduction measurement is performed by the battery performance inspection apparatus 200 shown in FIG. The battery performance inspection device 200 includes a measurement booth 210 in which a measurement sample of heat conduction characteristics is set, a control device 220, a display unit 230, and an input unit 240.

  The measurement booth 210 includes a heating element 212 and a temperature detector 214 with a measurement sample such as the MEA 21 interposed therebetween. The heating element 212 incorporates a planar heater that heats the measurement sample over almost the entire surface of the measurement sample such as the thin-leaf MEA 21. When heating the measurement sample by the heating element 212, the heating element 212 is placed in contact with or close to one surface of the measurement sample, in this embodiment, the upper surface, and in this state, the measurement sample is heated from the upper surface side to the entire upper surface of the sample. To do.

  The temperature detector 214 incorporates an infrared camera as an infrared detection device, and measures the heat transmitted through the measurement sample in the thickness direction at a plurality of locations on the entire surface of the measurement sample. Such measurement by the infrared camera is performed after the camera is focused on the measurement surface, specifically after the camera is focused on the lower surface of the measurement sample. Although the measurement results at these measurement points are indirect, they are used for determining the bonding status and battery characteristics as described later, so the number and distribution of the measurement points take into account the accuracy of the bonding status determination and characteristic evaluation. Can be determined. FIG. 4 is an explanatory diagram showing an example of a state of measurement of heat transmitted through a measurement sample such as the MEA 21 in its thickness direction. FIG. 4 (a) shows a state in which measurement is performed at a minimum measurement location necessary for performing statistical processing of heat conduction characteristics (thermal diffusivity) described later, and FIG. The measurement locations are defined in a matrix of m rows × n columns (m and n are natural numbers), and the measurement is shown at each measurement location SPm, n.

  The temperature detector 214 detects the amount of infrared radiation emitted from the entire lower surface of the measurement sample by using a built-in infrared detection device (infrared camera), and outputs a detection signal corresponding to the amount of infrared detected for the entire lower surface of the measurement sample. The temperature at each of the measurement points SP1 to SP3 (see FIG. 4A) or the temperature at each of the matrix measurement points SPm, n (see FIG. 4B) is detected by temperature. The temperature modulation analysis unit 222 of the control device 220 to which the detection signal of the device 214 is input is calculated as described later.

  The control device 220 calculates the heat conduction characteristics of the measurement sample, determines the joining status of the MEA 21 and the single cell 20, evaluates the battery characteristics, and the like, so that the heating element control unit 221, the temperature modulation analysis unit 222, the phase difference calculation unit 223, and the storage A unit 224, a heat conduction characteristic calculation unit 225, a deviation calculation unit 226, a bonding determination unit 227, and a characteristic evaluation unit 228. The heating element control unit 221 controls the temperature of the heating element 212 so that the heating temperature of the heating element 212 fluctuates periodically (temperature modulation), specifically, periodically generates heat at a predetermined angular frequency ω. In the measurement sample heated from the upper surface side by the heating element 212, temperature modulation of the angular frequency ω is induced on the upper surface of the sample, and the heat propagates through the measurement sample in the thickness direction. In this case, although the amount of heat attenuates in the process of heat propagation in the thickness direction of the measurement sample, the other surface of the measurement sample has a phase lag with respect to the temperature modulation induced on the upper side of the measurement sample, that is, It propagates to the lower surface and is detected by the temperature detector 214 as the propagation temperature on the lower surface side.

  The temperature modulation analysis unit 222 receives the infrared amount detection signal from the temperature detector 214, and converts the temperature conversion from the infrared amount detection signal to the measurement points SP1 to SP3 shown in FIG. Repeat for n. And the temperature modulation analysis part 222 calculates | requires the temperature which arises in each measurement location with elapsed time transition, and performs temperature modulation in the sample lower surface for every measurement location SP1-SP3 or every matrix measurement location SPm, n by the temperature transition. To analyze. FIG. 5 is an explanatory diagram showing the state of temperature modulation when the heating element 212 is heated and the state of temperature modulation of the detected temperature analyzed from the measured temperature.

  The phase difference calculation unit 223 calculates the phase difference between the temperature modulation on the lower surface of the sample and the temperature modulation when the heating element 212 is controlled to generate heat for each of the measurement points obtained from the temperature modulation analysis unit 222 (FIG. 5). reference). The storage unit 224 stores various maps used for characteristic evaluation. For example, as will be described later, from the calculated thermal conductivity characteristics, the bonding state determination as the MEA 21 and the bonding state determination in the single cell 20 in a state where the MEA 21 is sandwiched between the gas supply layers, The phase difference / heat conduction characteristic map used when calculating the heat conduction characteristic from the calculated phase difference, the heat conduction characteristic when each constituent member such as the MEA 21 of the single cell 20 is the measurement sample, and the heat conduction characteristic of the single cell 20 And the heat conduction / heat conduction correspondence map for each constituent member, and the constitution in which the deviation of the heat conduction characteristic when the constituent members of the single cell 20 are used as the measurement sample is associated with the battery characteristics of the single cell 20. Deviation / battery characteristic correspondence map for each member, deviation of heat conduction characteristics when single cell 20 in a state in which MEA 21 is sandwiched between gas supply layers on both sides is used as the measurement sample, and single cell 20 Corresponding deviation / battery characteristic correspondence map that correlates pond characteristics, deviation of thermal conductivity characteristics for each component, and deviation of thermal conductivity characteristics of single cell 20 with MEA 21 sandwiched between gas supply layers on both sides thereof The attached deviation / deviation correspondence map, the joining situation / battery characteristic correspondence map in which the joining situation determination result as the MEA 21 and the battery characteristics of the single cell 20 are associated, and the single cell 20 in a state where the MEA 21 is sandwiched between the gas supply layers. A cell joining state / battery characteristic correspondence map or the like in which the joining state determination result and the battery characteristics of the single cell 20 are associated with each other is stored.

  The heat conduction characteristic calculation unit 225 calculates the heat conduction characteristic for each measurement point SP based on the phase difference calculated for each of the plurality of measurement points SP. The deviation calculation unit 226 calculates the deviation of the heat conduction characteristic obtained for each measurement point SP. Since this deviation corresponds to the variation in the heat conduction characteristic obtained for each measurement point SP, the maximum value of the difference in the heat conduction characteristic and the average value of the difference are obtained by simple numerical calculation. In addition to being a deviation, the variance calculated using a statistical method can also be used as the deviation. The joining determination unit 227 determines the joining state in the MEA 21 based on the heat conduction characteristics calculated for each measurement point SP, or judges the joining state in the single cell 20 in a state where the MEA 21 is sandwiched between the gas supply layers. .

  The characteristic evaluation unit 228 actually calculates the deviation of the heat conduction characteristics actually obtained for the members such as the MEA 21 and the gas diffusion member 33 as the measurement sample, and the single cell 20 in a state where the MEA 21 is sandwiched between the gas supply layers on both sides. The obtained deviation of the heat conduction characteristic is compared with the map stored in the storage unit 224, and the battery characteristics of the single cell 20 using the member, and then the fuel cell after stacking the single cells are evaluated. Moreover, the characteristic evaluation part 228 is a result of the determination of the joining state of the constituent material obtained for the MEA 21 as the measurement sample, and the joining state of the constituent material obtained for the single cell 20 in a state where the MEA 21 is sandwiched between the gas supply layers on both sides. The determination result is compared with the map stored in the storage unit 224, and the battery characteristics of the single cell 20 using the MEA 21 and the fuel cell after stacking the single cells are evaluated.

  The control device 220 is configured using a CPU, ROM, RAM, memory and an input / output interface (I / O) configured as a logical operation circuit, and the CPU executes an existing program by executing a program written in the ROM. The heating element control unit 221 and the like described above are configured.

  The display unit 230 displays the heat conduction characteristics for each measurement region obtained by the deviation calculation unit 226 and the deviation thereof, the determination result of the bonding state obtained by the bonding determination unit 227, the evaluation result of the characteristic evaluation unit 228, and the like. The input unit 240 inputs sample thickness data for calculating heat conduction characteristics of the MEA 21 and the gas diffusion member 33 as a measurement sample, and data such as battery characteristics of a fuel cell manufactured using these members to the control device 220. To do.

  The principle of measuring the heat conduction characteristics using the battery performance inspection apparatus 200 in step S120 will be described. In the measurement sample in which the heating element 212 is in contact with or close to the upper surface, for example, the MEA 21, the periodic heat generation of the angular frequency ω occurs in almost the entire area of the upper surface of the MEA on the heating element 212 side. The MEA 21 propagates toward the lower surface, and the propagation heat is detected as a temperature by the temperature detector 214 and the temperature modulation analysis unit 222 as described above. Assuming that the thickness of the MEA 21 is d, in the process of heat propagation in the MEA 21 having this thickness d, heat is transmitted to the lower surface of the MEA with temperature modulation although the amount of heat is attenuated, causing a phase delay. The heat (propagating heat) is obtained as temperature modulation for each measurement point SP by the temperature detector 214 and the temperature modulation analysis unit 222. The phase delay of the temperature modulation described above is calculated as a phase difference for each measurement point SP by the phase difference calculation unit 223, and based on this phase difference, the heat conduction characteristic for each measurement point SP is calculated as a heat conduction characteristic calculation unit. 225.

  Here, when the thermal diffusivity of the MEA 21 is αMEA and the above phase difference is Δθ, the following relationship holds between the phase difference Δθ and the thermal diffusivity αMEA.

  Δθ = (√ (ω / 2αMEA)) · d− (π / 4) (1)

  In this equation (1), ω is an angular frequency generated by the heating element 212 and is a constant, thickness d is a numerical value given at the time of measurement, and phase difference Δθ is obtained by the phase difference calculation unit 223. . Therefore, the thermal diffusivity αMEA of the MEA 21 is calculated from the equation (1). For the calculation of the thermal diffusivity αMEA, it is easy to use the phase difference / heat conduction characteristic map described above stored in the storage unit 224 in association with the phase difference and the heat conduction characteristic (thermal diffusivity). The same applies to the gas diffusion members 33 to 36, and the thermal diffusivity of each of the gas diffusion members 33 to 36 can be obtained by giving the thickness d of each diffusion member at the time of the measurement. The thermal diffusivity α for each member obtained in this way is stored in the storage unit 224, and is used as supplementary data for the above correspondence map stored in the storage unit 224 in addition to battery characteristic evaluation described later. That is, the storage unit 224 stores the corresponding map data in advance, but supplements the map with data obtained in the battery manufacturing process, thereby increasing the number of data and improving the reliability of the map. Can do. If the map data stored in advance in the storage unit 224 is sufficient, such data supplementation can be omitted.

  This thermal diffusivity is obtained for each measurement location SP, and is nothing but the thermal conductivity characteristics of the MEA 21 or the gas diffusion members 33 to 36 at each measurement location, and the thermal diffusivity is determined by the MEA 21 that is the measurement object. There is a high correlation with the joining state of each of the constituent materials and the battery performance brought about by the MEA 21 and the like. Therefore, in the following description, the thermal diffusivity is referred to as an evaluation index for determining the joining state or evaluating the battery performance.

  Following such thermal diffusivity measurement (that is, temperature modulation phase difference analysis / thermal diffusivity calculation), based on the calculated thermal diffusivity obtained for each measurement location SP for the MEA 21, its constituent material in the MEA 21, that is, the electrolyte A bonding state between the layer 30 and the electrodes 31 and 32 on both sides thereof is determined (step S125). In this determination, the thermal conductivity characteristics / joining map stored in the storage unit 224 is referred to in association with the thermal diffusivity and the joining state of the constituent members in the MEA 21 (for example, joint quality). In this joining status determination, the MEA 21 determined to be defective in bonding is subjected to a re-joining process or the like to improve the joining status, and the MEA 21 determined to be in good bonding is carried to the subsequent process. In this case, the calculated thermal diffusivity as an evaluation index is stored in the storage unit 226 in association with the result of the joining state determination, and is also used as supplementary data for the correspondence map in the subsequent joining state determination. In this case, if the map data stored in advance by the storage unit 226 is sufficient, such data supplementation can be omitted.

  Following the joining determination of the MEA 21, the gas diffusion member 33 and the electrode side gas diffusion member 34 are joined, the gas diffusion member 35 and the electrode side gas diffusion member 36 are joined, and the gas supply layer 22 and the gas supply layer are joined. 23 is produced (step S130). The gas diffusion members may be bonded to each other by an appropriate bonding method, for example, a pressing method so as not to impair the gas diffusion function.

  Even in the gas supply layers 22 and 23 thus manufactured, they are constituent members of the MEA 21 and the single cell 20. Therefore, also for this component member, calculation of the above-described battery performance evaluation index (thermal diffusivity) of each gas supply layer 22 and 23 using the battery performance inspection apparatus 200 described in step S120 and the evaluation index A variation (deviation) is obtained (step S140). By the way, since the gas supply layers 22 and 23 are the joined bodies of the gas diffusion members described above, the evaluation index obtained for each of the gas diffusion members 33 to 36 varies (deviation of thermal diffusivity) and is produced from these members. By comparing the variation of the evaluation index obtained for the gas supply layers 22 and 23 (deviation of the thermal diffusivity), the transition of the variation of the evaluation index (thermal diffusivity deviation) due to bonding can be obtained. Therefore, while changing the joining state of the gas diffusion member, calculation / contrast of the variation of the evaluation index (deviation of the thermal diffusivity) of each of the gas diffusion members and the gas supply layers 22 and 23 which are the joined members is performed. In addition, it is possible to obtain an optimum joining state for producing the gas supply layers 22 and 23 by joining the gas diffusion members. Further, similarly to the joining determination of the MEA 21, based on the evaluation index (thermal diffusivity) obtained for the gas supply layers 22 and 23, the joining state of the constituent members of the gas supply layers 22 and 23 (the gas diffusion member 33 and the electrode) It is also possible to determine the joining state of the side gas diffusion member 34 and the joining state of the gas diffusion member 35 and the electrode side gas diffusion member 36).

  Variations in the evaluation indices (thermal diffusivity deviation) of the gas supply layers 22 and 23 thus obtained are stored in the storage unit 226. In addition to the battery characteristic evaluation described later, the above correspondence map stored in the storage unit 226 is supplemented. Also used as data. In this case, if the map data stored in advance by the storage unit 226 is sufficient, such data supplementation can be omitted.

  When the gas supply layers 22 and 23 are formed from a single gas diffusion member, the calculation of the variation in the evaluation index of the single gas diffusion member (the deviation of the thermal diffusivity) has been performed in step S120. Therefore, steps S130 and 140 are not necessary.

  Next, the single cell 20 is produced (step S150). Here, the joining means that the two members are positively fixed so that the contact area increases as compared with the case where the two members are simply laminated. The joining of the MEA 21 and the electrode-side gas diffusion members 34 and 36 in the gas supply layers 22 and 23 on both sides thereof can be performed by, for example, hot pressing. As described above, by applying heat and pressure, the paste described above that constitutes the electrodes 31 and 32 is softened by heat, and the softened paste is adapted to the entire porous surfaces of the electrode-side gas diffusion members 34 and 36. Both are crimped while increasing the contact area.

  Next, for the single cell 20, as described in step S <b> 120, the evaluation index (thermal diffusivity) for each measurement point SP is calculated, and the variation (deviation of the thermal diffusivity) is measured using the battery performance inspection apparatus 200. Calculate (step S160). Since the unit cell 20 is a joined body of the respective constituent members described above, the variation of the evaluation index (deviation of the thermal diffusivity) is the variation of the evaluation index included in the respective constituent members (deviation of the thermal diffusivity). ) Is affected by bonding. By comparing the variation of the evaluation index (thermal diffusivity deviation) of the single cell 20 obtained in step S160 with the variation of the evaluation index (thermal diffusivity deviation) of each constituent member obtained in the steps described above, It is possible to obtain a change in evaluation index variation (thermal diffusivity deviation) due to bonding. Therefore, calculation / contrast of variation (deviation in thermal diffusivity) of the evaluation index of the single cell 20 and each of its constituent members while changing the joining state (for example, temperature and pressing force) by hot pressing when the single cell 20 is manufactured. By performing the above, it is possible to obtain an optimum bonding state in manufacturing the single cell 20 by bonding the gas supply layers 22 and 23 to the MEA 21.

  The variation of the evaluation index obtained for the single cell 20 (deviation of the thermal diffusivity) is used for the later-described battery characteristic evaluation stored in the storage unit 226, and the variation of the evaluation index of the single cell 20 (thermal diffusivity). Deviation) in correspondence with the battery characteristics of the single cell 20, variation in evaluation index of each component of the single cell 20 (deviation of thermal diffusivity), and variation in evaluation index of the single cell 20. It is also used as supplementary data for a deviation / deviation correspondence map that associates (deviation of thermal diffusivity). Even if there are variations in the evaluation index of the single cell 20 (deviation of thermal diffusivity), such data supplementation can be omitted if the map data stored in advance by the storage unit 226 is sufficient.

  Following the thermal diffusivity measurement (temperature modulation phase difference analysis / thermal diffusivity and deviation calculation) for the single cell 20 in step S160, based on the calculated thermal diffusivity obtained for each measurement point SP for the single cell 20. Then, the joining state of the constituent material in the single cell 20, that is, the MEA 21 and the gas supply layers 22 and 23 on both sides thereof is determined (step S 165). Also in this determination, as in the case of MEA 21, the thermal diffusivity and the heat conduction characteristics / joint stored in the storage unit 224 in association with the joining state of the constituent members in the single cell 20 (for example, good or bad jointability). A map is referenced. In this bonding status determination, the unit cell 20 determined to be defective in bonding is subjected to a bonding process or the like again to improve the bonding status, and the unit cell 20 determined to be in good bonding is carried to the subsequent process. In this case, the calculated thermal diffusivity as an evaluation index is stored in the storage unit 226 in association with the result of the joining state determination, and is also used as supplementary data for the correspondence map in the subsequent joining state determination. In this case, if the map data stored in advance by the storage unit 226 is sufficient, such data supplementation can be omitted.

  Following the joining determination of the MEA 21, based on the variation of individual evaluation indexes (deviation of the thermal diffusivity) of each component of the single cell 20 and the variation of the evaluation index as the single cell 20 (deviation of the thermal diffusivity), The battery characteristics exhibited by the single cell 20 are evaluated (step S170). Battery characteristic evaluation through variation in evaluation index (deviation of thermal diffusivity) is based on the fact that the thermal diffusivity, which is an evaluation index, is highly correlated with battery characteristics. Such battery characteristic evaluation can be performed by the following method. In this embodiment, the thermal diffusivity as an evaluation index is obtained based on the phase difference of temperature modulation, and the deviation is used for battery characteristic evaluation.

  In the first evaluation method, the variation in the evaluation index of the single cell 20 (deviation in thermal diffusivity) measured in step S160 is the variation in the evaluation index in the single cell 20 stored in the storage unit 226 (deviation in thermal diffusivity). The battery characteristics of the single cell 20 are evaluated in comparison with the deviation / battery characteristic correspondence map of the battery characteristics of the single cell 20. In the second evaluation method, the variation in the evaluation index of each component of the single cell 20 measured in Steps S120 and 140 (the deviation of the thermal diffusivity) is the variation in the evaluation index of each component stored in the storage unit 226 ( The thermal diffusivity of the single cell 20 is calculated by comparing with a deviation / deviation correspondence map of the variation of the thermal diffusivity) and the variation of the evaluation index of the single cell 20 (deviation of the thermal diffusivity). Then, the variation of the evaluation index of the single cell 20 (deviation of the thermal diffusivity), the variation of the evaluation index of the single cell 20 (deviation of the thermal diffusivity) stored in the storage unit 226, and the battery characteristics of the single cell 20 The battery characteristics of the single cell 20 are evaluated in comparison with the deviation / battery characteristics correspondence map.

  In this embodiment, since the variation (evaluation of thermal diffusivity) of the evaluation index of the single cell 20 is actually measured and calculated, the first evaluation method is simple. In this method, the variation (deviation in thermal diffusivity) of the evaluation indexes of the constituent members in steps S120 and S140 can be omitted. However, the joining of the members is made through a comparison between the variation of the evaluation index of each constituent member (deviation of the thermal diffusivity) and the variation of the evaluation index of the single cell 20 produced through the joining of the constituent members (deviation of the thermal diffusivity). This is useful from the viewpoint of manufacturing control and quality control because it can infer the effect on the variation of evaluation index (deviation of thermal diffusivity). On the other hand, in the second evaluation method, the variation of the evaluation index (thermal diffusivity deviation) of the single cell 20 in step S160 can be omitted, but as in the first method, the evaluation index of the single cell 20 It is beneficial from the viewpoint of manufacturing control and quality control to perform variation (deviation of thermal diffusivity).

  The deviation / battery characteristic correspondence map and the deviation / deviation characteristic correspondence map used for such battery characteristic evaluation can be constructed as follows. First, as in the present embodiment, the variation of the evaluation index (thermal diffusivity deviation) of the single cell 20 is acquired, the fuel cell having the acquired single cell 20 is mounted on the system and operated, and the battery characteristics are obtained. (For example, output current / voltage characteristics, internal resistance, etc.) are obtained. This is repeated, and a deviation / battery characteristic correspondence map in which the variation in evaluation index of the single cell 20 (thermal diffusivity deviation) is associated with the battery characteristics of the single cell 20 is constructed and stored in the storage unit 226. With respect to the deviation / deviation correspondence map, calculation of variation in evaluation index of components (thermal diffusivity deviation) in steps S120 and 140 of the present embodiment and variation in evaluation index of single cell 20 in step S160 (thermal diffusivity) Deviation) is calculated every time the fuel cell is manufactured, and a deviation / deviation correspondence map in which both thermal diffusivities are associated is constructed and stored in the storage unit 226.

  When the battery characteristics evaluation of the single cell 20 is completed in this way, the separators 24 and 25 are joined to both sides of the single cell 20 determined as appropriate by the evaluation (step S180). Since the separators 24 and 25 are joined to the gas diffusion members 33 and 35 in the gas supply layers 22 and 23, the joining with the gas diffusion members may be performed by an appropriate technique such as welding. Welding enables joining of the gas diffusion members 33 and 35 and the separators 24 and 25 with a molten base material and / or with a molten filler material while increasing the contact area. To do.

  Subsequently, in units of single cells 20 sandwiched between separators 24 and 25, a predetermined number of these are stacked in a predetermined order (so that the single cells 20 in FIG. 1 are repeatedly formed) to assemble a stack structure, and the stacking direction A predetermined pressing force is applied to hold the entire structure to complete the fuel cell (step S190). In addition, the assembly process of step S190 includes processes such as disposing a sealing member such as the gasket described above on the outer peripheral portion of the laminate, or forming a refrigerant flow path between adjacent single cells.

  Here, when a refrigerant flow path or the like is not formed between adjacent single cells, the gas diffusion members 33 and 34 of the gas supply layers 22 and 23 may be bonded to both surfaces of the separator. That is, a single separator may be stacked and bonded so as to be shared by the single cells 20 on both sides.

  As described above, according to the present embodiment in which the joining state determination (steps S125 and 165) using the battery performance inspection apparatus 200 is performed, the evaluation of the single cell 20 and its constituent members measured in the process of manufacturing the fuel cell is performed. Based on the index (thermal diffusivity) and the previously stored thermal conductivity characteristics / bonding map, determination of the bonding state of the respective constituent materials in the MEA 21 or the single cell 20 as the layer structure of the fuel cell, for example, A pass / fail judgment can be made. That is, in the joining state inspection of the present embodiment, the temperature at each measurement location is measured when determining the joining state of the constituent members of the MEA 21 and the single cell 20 as the layer structure of the fuel cell. Instead of using this value, the thermal diffusivity based on the phase difference of the temperature modulation for each measurement point is obtained as an evaluation index as described above, and this evaluation index is used for the determination of the joining state. The thermal diffusivity based on the measured and calculated phase difference of the temperature modulation is nothing but the thermal conductivity characteristics of the measurement point SP, and this thermal conductivity characteristics are the characteristics of the individual materials of the single cell 20 that is the layer structure, the material There is a high correlation with the state of bonding between each other. As a result, according to the inspection method of the joining state between the constituent materials using the battery performance inspection apparatus 200 of the present embodiment, the reliability of the judgment of the joining state between the constituent materials of the fuel cell can be improved. Moreover, since it is not necessary to put the fuel cell in an operating state when determining the joining state of the fuel cell, it is simple. Further, not only as a single cell 20 that is one battery constituent unit of a fuel cell, but also as an MEA 21 that is a constituent material thereof, a joining state judgment between constituent materials can be performed in the manufacturing process. In addition, it is possible to make a joint quality determination as the single cell 20 and a joint quality judgment as the MEA 21, which can contribute to quality improvement.

  Further, in the present embodiment, the battery performance inspection apparatus 200 is used to determine the variation (deviation in thermal diffusivity) of the single cell 20 and its constituent members in the course of manufacturing the fuel cell and to store them in advance. The battery characteristics of the fuel cell after manufacture can be evaluated based on the deviation / deviation correspondence map of FIG. That is, in the performance evaluation of the present embodiment, the temperature of each measurement location is measured when evaluating the battery characteristics of the fuel cell (specifically, the single cell 20), but the measured temperature value is not used. As described above, the thermal diffusivity based on the phase difference of each temperature modulation is obtained as an evaluation index, and the deviation of the thermal diffusivity, which is a variation of the evaluation index, is used. The thermal diffusivity based on the measured and calculated phase difference of the temperature modulation is nothing but the thermal conductivity characteristics of the measurement point SP, and this thermal conductivity characteristics are the characteristics of the individual materials of the single cell 20 that is the layer structure, the material There is a high correlation with the state of bonding between them, and thus with the cell characteristics of the fuel cell. As a result, according to the battery characteristic evaluation method using the battery performance inspection apparatus 200 of the present embodiment, the reliability of the fuel cell characteristic evaluation can be improved. Moreover, since it is not necessary to put the fuel cell in an operating state when evaluating the cell characteristics of the fuel cell, it is simple. Moreover, since the battery performance evaluation as the single cell 20 that is one battery constituent unit of the fuel cell can also be performed in the manufacturing process, it is possible to judge the quality of the single cell 20 based on this evaluation, which can contribute to quality improvement. .

  In addition, in this embodiment, the variation of the evaluation index (thermal diffusivity deviation) of the unit cell 20 itself and the variation of the evaluation index of the individual cell constituent members joined when the unit cell 20 is manufactured (thermal diffusion). Since the difference between the two variations is calculated, it is possible to optimize the joining condition of the member joining based on the change in the evaluation index variation (thermal diffusivity deviation) based on the member joining. it can. For this reason, it is preferable also from manufacture control and quality improvement.

  Moreover, in a present Example, the thermal diffusivity which is the evaluation index of the single cell 20 and its component members can be grasped | ascertained also as distribution in measurement location SP1-SP3 shown in FIG. 4, or measurement location SPm, n. . Since the distribution of the evaluation index (thermal diffusivity) correlates with the distribution of the battery characteristics, the gas supply by the gas supply layers 22 and 23 is changed in accordance with the distribution of the evaluation index (thermal diffusivity). You can also By doing so, the electrochemical reaction that proceeds in the MEA 21 becomes uniform on the surface of the MEA film, so that the battery characteristics can be improved.

  Next, an example of measurement by the battery performance inspection apparatus 200 shown in FIG. 3 will be described. The measurement sample was an MEA 21 in which the electrolyte layer 30 was sandwiched between electrodes 31 and 32 on both sides thereof. In producing the MEA 21, a transfer method using an electrode transfer sheet among the methods described above was employed. That is, the electrode layer 30 is sandwiched between two electrode transfer sheets obtained by applying a catalyst-supported carbon powder paste such as platinum to a Teflon sheet and dried, and then the Teflon sheet is peeled off after being hot-pressed at a predetermined temperature and pressure. The transfer sheet was transferred to both sides of the electrolyte layer 30 to obtain MEA 21. And about this MEA21, the average value of the thermal diffusivity calculated | required about measurement location SP1-SP3 shown to Fig.4 (a) by the battery performance inspection apparatus 200 was made into the thermal diffusivity of MEA21, and the deviation was also calculated | required. In this case, the variance of the thermal diffusivity for each of the measurement points SP1 to SP3 was taken as the deviation. That is, when the thermal diffusivities of the measurement locations SP1 to SP3 are αSP1 to αSP3 and the number of samples of the thermal diffusivity is n, the dispersion (deviation) is obtained by the following equation.

Dispersion = ((αSP1 ² + αSP2 ² + αSP3 ² ) − (αSP1 + αSP2 + αSP3) ² / n) / (n−1)

  The variance obtained by the above equation is a value obtained by dividing the sum of squares of the thermal diffusivities αSP1 to αSP3 of the measurement points SP1 to SP3 by a number (n−1) that is one less than the number of thermal diffusivity samples. The smaller the value, the smaller the variation in the thermal diffusivities αSP1 to αSP3 of the measurement points SP1 to SP3. FIG. 6 is an explanatory diagram illustrating the comparison between the measurement results of thermal diffusivity of the comparative example and the example product and the evaluation items.

  As shown in FIG. 6, the comparative example, Example 1, and Example 2 were evaluated. The comparative example and the example are different from each other in the joining method at the time of manufacturing the MEA 21. The comparative example is a standard joining method, for example, a normal temperature at the time of hot pressing restricted by the properties of the Nafion film constituting the MEA 21 ( The MEA 21 was hot-pressed at a normal pressure (standard pressure) at the time of hot pressing, which is restricted by the properties of the Nafion film, in a thermal environment of (standard temperature). In Example 1, in the electrode hot press at the time of manufacturing the MEA 21 at the standard temperature and the standard pressure, a plasticizer was spray-coated on the film surface, and the electrode was impregnated at about 10 wt% with the plasticizer solution. Hot pressed. In Example 2, hot pressing was performed so that the pressure was concentrated on the electrode surface of the electrode that had been transferred by the electrode transfer sheet during the hot pressing of the MEA 21 at the standard temperature and the standard pressure.

  About such comparative example and Examples 1-2, while having measured the thermal diffusivity with the battery performance inspection apparatus 200 as stated above, the electrical property test was done.

In the battery characteristic test, the MEA 21 was heated to about 80 ° C., both electrodes were pressurized to about 1.5 bar, and low humidified gas (hydrogen gas / air) was applied to both electrodes (supply layer) during normal operation. The gas was supplied at a gas flow rate of 150%, continuously operated for 10 minutes at a current density of 1.0 A / cm ² , and the output voltage at that time was measured for relative comparison (reference example). The result is as shown in the figure. As shown in the figure, it was found that even if the constituent materials of the MEA 21 are the same, the thermal diffusivity / electrical characteristics are different if the joining conditions are different. This means that the joining state of the constituent materials in the MEA 21 can be determined by the thermal diffusivity.

  In particular, there was a high correlation between the thermal diffusivity and the electrical characteristics, and it was confirmed that the battery characteristics improved as the thermal diffusivity increased and the deviation (dispersion) decreased. That is, Example 1 and Example 2 have substantially the same thermal conductivity, but Example 2 with a smaller deviation has been found to have higher battery characteristics. Therefore, as described above, the electrical characteristics of the MEA 21 can be accurately evaluated through the measurement of thermal conductivity characteristics (thermal diffusivity). In addition, since a correlation can be obtained with respect to the bonding conditions, the thermal diffusivity, and the electrical characteristics, it is possible to determine whether or not the bonding is good via the thermal diffusivity measurement. Such a determination is simple because it requires only a simple thermal diffusivity measurement and does not require an operation test with an actual machine. In other words, by setting the joining conditions, it is possible to easily manufacture the MEA 21 having a desired thermal diffusivity and its variation range, and thus electrical characteristics. Specifically, it is possible to improve the thermal diffusivity and, consequently, the battery characteristics by a simple method such as adding a plasticizer and concentration of pressure on the electrode surface during pressurization.

  Further, since the MEA 21 (Example 1) has no practical problem with the electrical characteristics of Example 1, the MEA 21 having a thermal diffusivity distribution of 0.2 or less has high electrical characteristics. It can be said that a fuel cell equipped with

  As described above, the thermal diffusivity and electrical characteristics are improved when the joining conditions are changed because the joining property of each material in the MEA 21 is improved, so that the increase in resistance at the joining interface and the flooding are eliminated. Is expected. The above-described joining state determination / characteristic evaluation is not limited to the case where the measurement sample is the MEA 21, but can also be performed for MEGAs in which the MEA 21 is sandwiched between the gas supply layers 22 and 23 on both sides thereof.

  Next, a modified example of the battery performance inspection apparatus 200 will be described. FIG. 7 is a schematic diagram of a battery performance inspection apparatus 200 according to a first modification. This modification is characterized in that a plurality of heating locations on the upper surface of the measurement sample such as the MEA 21 are provided corresponding to the measurement locations SPm, n by the temperature detector 214.

  As shown in the figure, the battery performance inspection apparatus 200 of this modification has a heating element 212 provided with heating protrusions Ht formed in a convex shape so as to come into contact with the upper surface of the measurement sample. The heating protrusions Ht are formed corresponding to the measurement points SPm, n shown in FIG. 4, and each measurement point SPm, n heats the measurement sample from the upper surface of the sample while causing temperature modulation. Even in this modification, the same effects as those of the above-described embodiment can be obtained.

  FIG. 8 is a schematic diagram of a battery performance inspection apparatus 200 according to another modification. This modification is to obtain the phase difference / deviation at a plurality of matrix-like measurement locations as shown in FIG. 4 while changing the heating location on the upper surface of the measurement sample such as the MEA 21 and the measurement location opposite thereto. There are features.

  As shown in the figure, a battery performance inspection device 200 of this modification includes a heating probe 213 for applying heat to a thin-leaf measurement sample, and a detection probe 215 for detecting heat transmitted through the measurement sample in its thickness direction. The two probes are driven in the xy plane by the xy drive unit 217. The heating probe 213 contacts the upper surface of the measurement sample, and heats the measurement sample (MEA 21, single cell 20, gas diffusion member 33, etc.) while causing temperature modulation at the contact location. The detection probe 215 outputs the detected temperature at the contact location (ie, measurement location) to the control device 220. Thereby, the control device 220 performs the phase difference calculation of the temperature modulation at the measurement location by the detection probe 215 and calculates the thermal diffusivity based on this. In this modification, the xy drive unit 217 is controlled from the control device 220 side to move the heating probe 213 and the detection probe 215, change the heating location and the measurement location, and also perform temperature modulation in the changed location. Phase difference calculation and thermal diffusivity calculation based on this. Thus, the thermal diffusivity is obtained corresponding to a plurality of locations, specifically, the matrix-like measurement locations shown in FIG. 4, and the deviation is used for battery characteristic evaluation. Even in this modification, the same effects as those of the above-described embodiment can be obtained.

  FIG. 9 is a schematic diagram of a battery performance inspection apparatus 200 according to a modification that performs measurement also in the thickness direction of the measurement sample, and FIG. 10 is an explanatory diagram that schematically shows a state of measurement in the sample thickness direction. In this modification, a multilayer structure such as MEA 21 or single cell 20 is used as a measurement sample, and phase difference / deviation calculation at a plurality of measurement points in a matrix form as shown in FIG. 4 is performed at several positions in the thickness direction of the multilayer structure. This is characterized in that the heat conduction characteristics (thermal diffusivity) of the multilayer structure are obtained three-dimensionally in the vertical and horizontal directions and in the thickness direction.

  As shown in FIG. 9, the battery performance inspection device 200 of this modification example drives a temperature detector 214 incorporating an infrared camera as an infrared detection device along the z direction by a z drive unit 218. In this case, since the z direction is the thickness direction in the measurement sample (for example, the single cell 20), the temperature detector 214 is driven along the thickness direction of the measurement sample (for example, the single cell 20) by the z driving unit 218. To do. In the temperature detector 214 in this modification, since the focal length Ss of the infrared camera is constant, the temperature detector 214 is driven by the z drive unit 218 as shown in FIG. At each location in the thickness direction of the single cell 20, the temperature modulation measurement at the measurement locations SPm, n and the above-described phase difference / deviation based on this can be obtained. Note that when the temperature detector 214 is driven by the z driving unit 218, a driving amount is input from the input unit 240. Therefore, various measurement locations in the thickness direction can be set by changing the state of the input.

  In this case, the gas diffusion members 33 and 35 on the measurement side of the temperature detector 214 are formed of a carbon material such as carbon paper, or a metal member such as foam metal or metal mesh as described above. As shown in FIG. 10, even if the measurement location (measurement surface) that matches the focal length Ss is in the gas diffusion members 33 and 35, infrared radiation from the measurement location can be detected by the temperature detector 214.

  As apparent from FIG. 10, in this modification, in the state of the single cell 20 as a semi-finished product after joining the respective members, temperature modulation measurement is performed in a non-destructive and non-contact manner, and a phase difference is calculated from the result. Deviation calculation and characteristic evaluation as described above can be performed. In addition, in this modification, the gas diffusion members 33 and 35 as a single unit can be measured in three dimensions including the thickness direction in the state of the single cell 20 as a semi-finished product, and the characteristics can be evaluated. It becomes possible to adjust the heat conduction characteristics of the gas diffusion members 33 and 35 by re-pressurizing and joining in the single cell 20 which is a semi-finished product. Further, by matching the focal length Ss of the temperature detector 214 with the joint surface between the gas diffusion members 33 and 35 and the electrode-side gas diffusion members 34 and 36 in the lower layer, the joint state of both members can be changed at the joint surface. It is preferable that the quality can be judged from the temperature modulation measurement and the characteristic evaluation.

  By the way, as described above, the heat conduction characteristic is obtained from the measured temperature modulation, and this heat conduction characteristic depends on the joining state of the member and the property of the member itself (for example, material non-uniformity, uniformity, etc.). . Therefore, if measurement is performed by the battery performance inspection apparatus 200 of this modification, it is possible to grasp the material variation status of the gas diffusion members 33 and 35 from the three-dimensional heat conduction characteristic distribution including the thickness direction. .

  In addition, although the single cell 20 was demonstrated to the example as a measurement sample, MEA21 can be used as a measurement sample, or the gas supply layer 22 which joined the gas diffusion member 33 and the electrode side gas diffusion member 34 can also be used as a measurement sample.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and embodiments, and can of course be implemented in various modes without departing from the gist of the present invention. is there. For example, in the above embodiment, the temperature is detected in the matrix measurement region (measurement location) SPm, n by the infrared detector incorporated in the temperature detector 214, but the temperature as shown in FIG. Detection probes for detection may be provided in a matrix.

  Further, although the thermal diffusivity is used as an evaluation index, as is clear from the above-described equation (1), the thermal diffusivity has a corresponding relationship with the phase difference Δθ. Therefore, the phase difference itself obtained by the battery performance inspection apparatus 200 can be used as an evaluation index when evaluating the battery performance, and the deviation of the phase difference can be used instead of the deviation of the thermal diffusivity.

  In the battery performance inspection apparatus 200 shown in FIG. 9, the temperature detector 214 is driven. However, the measurement sample may be driven with respect to the temperature detector 214. Alternatively, the infrared camera incorporated in the temperature detector 214 can be of a variable focal position type, and the measurement value in the thickness direction can be changed by changing the focal position.

It is explanatory drawing explaining schematic structure of the fuel cell used as the evaluation object in an Example. It is process drawing showing the manufacturing method of the fuel cell of a present Example. It is the schematic of the test | inspection apparatus which performs characteristic evaluation based on the heat conduction characteristic of each structural member in the case of battery manufacture. It is explanatory drawing which shows the mode of the measurement of the heat which transmitted measurement samples, such as MEA21, to the thickness direction. It is explanatory drawing which shows the mode of the temperature modulation at the time of heating-controlling the heat generating body 212, and the mode of the temperature modulation of the detected temperature analyzed from the measured temperature. It is explanatory drawing which compares and demonstrates the measurement result and evaluation item of the thermal diffusivity of a comparative example and an Example goods. It is the schematic of the battery performance inspection apparatus 200 of a 1st modification. It is the schematic of the battery performance inspection apparatus 200 of another modification. It is the schematic of the battery performance inspection apparatus 200 of the modification which performs a measurement also in the thickness direction of a measurement sample. It is explanatory drawing which shows typically the mode of the measurement in a sample thickness direction.

Explanation of symbols

20 ... Single cell 21 ... MEA (Membrane Electrode Assembly)
22, 23 ... Gas supply layer 24, 25 ... Separator 30 ... Electrolyte layer 31, 32 ... Electrode 33, 35 ... Gas diffusion member 34, 36 ... Electrode side gas diffusion member 200 ... Battery performance inspection device 210 ... Measurement booth 212 ... Heat generation Body 213 ... Heating probe 214 ... Temperature detector 215 ... Detection probe 217 ... xy drive unit 218 ... z drive unit 220 ... Control device 221 ... Heating element control unit 222 ... Temperature modulation analysis unit 223 ... Phase difference calculation unit 224 ... Storage unit 225 ... Heat conduction characteristic calculation unit 226 ... Storage unit 226 ... Deviation calculation unit 227 ... Junction determination unit 228 ... Characteristic evaluation unit 230 ... Display unit 240 ... Input unit SP1-SP3, SPm, n ... Measurement location

Claims (10)

A method for inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
When heating the layer structure from one side of the front and back surfaces of the layer structure, the layer structure is heated while performing temperature modulation at a predetermined frequency, and the heating is performed over the heating region on the one surface. Inducing a temperature modulation on the one side of the layer structure,
The temperature modulation of heat transmitted in the thickness direction of the layer structure is measured at a plurality of measurement points included in the measurement area on the other surface side of the layer structure facing the heating area,
Obtaining a phase difference between the measured temperature modulation and the temperature modulation when the layer structure is heated from the one surface side for each of the plurality of measurement points;
Based on the phase difference obtained for each measurement location, obtain the thermal conductivity characteristics of the fuel cell in the layer direction for each measurement location of the layer structure,
A method for inspecting a fuel cell, wherein the joining state of the constituent members of the layer structure is determined based on the heat conduction characteristics obtained for each measurement location. A method for inspecting a fuel cell having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
When heating the layer structure from one side of the front and back surfaces of the layer structure, the layer structure is heated while causing temperature modulation at a predetermined frequency, and the one of the layer structures is heated at the heating location. Induces temperature modulation on the side of the surface,
The temperature modulation of the heat transmitted in the thickness direction of the layer structure is measured at a measurement location on the other surface side of the layer configuration facing the heating location,
Obtaining a phase difference between the measured temperature modulation and the temperature modulation when the layer structure is heated at the heating portion on the one surface;
Based on the obtained phase difference, obtain the heat conduction characteristics of the fuel cell in the layer direction at the measurement location of the layer structure,
While changing the heating location and the measurement location in the layer structure, and determining the phase difference at a plurality of locations of the layer structure, the heat conduction characteristics based on the phase difference is determined at a plurality of locations,
A method for inspecting a fuel cell, wherein a joining state of constituent members of the layer structure is determined based on the heat conduction characteristics obtained at the plurality of locations. An inspection method for a fuel cell according to claim 1 or 2, wherein
In inducing the temperature modulation,
A fuel gas supply layer that receives a supply of fuel gas of the electrolyte in the layer structure and sends the gas to one of the electrodes, and a supply of an oxidizing gas containing a substance that contributes to the oxidation of the conduction species. With respect to the gas supply layer-containing structure in which the layer structure is joined and sandwiched by the oxidizing gas supply layer that sends the gas to the other electrode, the temperature is measured from one side of the front and back surfaces of the gas supply layer-containing structure. Inducing the temperature modulation by heating the gas supply layer containing structure while causing the modulation,
In measuring the temperature modulation,
A method for inspecting a fuel cell, wherein temperature modulation of heat transmitted in the thickness direction of the gas supply layer-containing structure is measured on the other surface side of the gas supply layer-containing structure. A method for inspecting a fuel cell according to any one of claims 1 to 3,
Based on the obtained deviation of the heat conduction characteristic and the characteristic correspondence in which the deviation is associated with the battery characteristic of the fuel cell, or the determined joining state and the judged state are the battery characteristics of the fuel cell. A fuel cell inspection method for evaluating cell characteristics of the fuel cell based on the associated characteristic correspondence. A method for inspecting a fuel cell according to any one of claims 1 to 4,
In measuring the temperature modulation,
A temperature measuring device that includes an infrared camera that receives infrared rays, and that receives infrared rays emitted from a measurement object at the focal position of the camera with the infrared camera and measures the temperature of the measurement object at the focal position in a non-contact manner. Use
While changing the focal position of the infrared camera of the temperature measuring device in the thickness direction of the layer structure or the gas supply layer-containing structure that is the measurement object, temperature modulation at a position that matches the focal position is performed. Measuring method of fuel cell. A fuel cell inspection apparatus having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
A heat generating portion that heats the heat generating portion while causing temperature modulation at a predetermined frequency, and heats the layer structure from one side of the front and back surfaces by the heat generating portion, Heating means for inducing temperature modulation on the side of the surface,
Measuring means for measuring temperature modulation of heat transmitted in the thickness direction of the layer structure at a plurality of measurement points on the other surface side of the layer structure;
Obtaining the phase difference between the measured temperature modulation and the temperature modulation when heating the layer structure from the one surface side for each measurement location, based on the phase difference for each measurement location, A heat conduction characteristic calculating means for obtaining a heat conduction characteristic of the fuel cell in a layer direction for each measurement location of the layer structure;
Based on the heat conduction characteristics obtained for each measurement location, it comprises a joining determination means for judging the joining status of the constituent members of the layer structure,
The heating means heats the layer structure on the one surface side by the heat generating portion so as to induce the temperature modulation at a plurality of heating points facing each of the plurality of measurement points. Inspection of a fuel cell apparatus. The fuel cell inspection device according to claim 6,
The heating means includes
The heating unit includes a planar heating unit that heats the layer structure over a heating region including the plurality of heating points, and a plurality of heat sources that heat the layer structure at the plurality of heating points. A fuel cell inspection device having any one of heat generating portions. A fuel cell inspection apparatus having a layer structure in which an electrolyte is sandwiched between a pair of electrodes,
A heat generating portion that heats the heat generating portion while causing temperature modulation at a predetermined frequency, and heats the layer structure from one side of the front and back surfaces by the heat generating portion, Heating means for inducing temperature modulation on the side of the surface,
Measuring means for measuring temperature modulation of heat transmitted through the layer structure in the thickness direction at a measurement point on the other surface side of the layer structure opposite to a heating point of the layer structure by the heating unit; ,
While calculating the phase difference between the measured temperature modulation and the temperature modulation when the layer structure is heated from the one surface side, the heating location of the layer structure by the heating unit of the heating means And the phase difference calculating means for calculating the phase difference at a plurality of locations of the layer structure by changing the measurement location of the measuring means in the layer structure.
Based on the phase difference calculated at the plurality of places, a heat conduction characteristic calculating means for obtaining a heat conduction characteristic of the fuel cell in the layer direction for each of the plurality of places of the layer structure,
An inspection apparatus for a fuel cell, comprising: a joining determination unit that judges a joining state of the constituent members of the layer structure based on the heat conduction characteristics obtained for each measurement location. A fuel cell inspection apparatus according to any one of claims 6 to 8,
Deviation calculating means for calculating a deviation of the obtained heat conduction characteristic;
Deviation correspondence characteristic storage means for storing characteristic correspondence in which the deviation of the heat conduction characteristic and the battery characteristic of the fuel cell are associated;
A joining correspondence characteristic storage means for storing a characteristic correspondence in which the joining state of the constituent members of the layer structure is associated with the cell characteristics of the fuel cell;
Based on the battery characteristic evaluation of the fuel cell based on the calculated deviation and the characteristic correspondence stored by the deviation correspondence characteristic storage unit, and based on the determined determination situation and the characteristic correspondence stored by the joint correspondence characteristic storage unit. An inspection device for a fuel cell, comprising: evaluation means for performing at least one cell characteristic evaluation of the cell characteristics evaluation of the fuel cell. A fuel cell inspection apparatus according to any one of claims 6 to 9,
The measuring means includes
A temperature measuring device including an infrared camera that receives infrared rays, wherein infrared rays emitted from a measurement object at a focal position of the infrared camera are received by the infrared camera, and a temperature of the measurement object at the focal position is determined as non-temperature. It has a temperature measurement device that measures contact,
While changing the focal position of the infrared camera of the temperature measuring device in the thickness direction of the layer structure or the gas supply layer-containing structure that is the measurement object, temperature modulation at a position that matches the focal position is performed. Measure fuel cell inspection equipment.

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