JP5369740B2 - Manufacturing method of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell equipped with an electrode in a distribution state in which a distribution state of electrolyte is as aimed at in a thickness direction. <P>SOLUTION: The method for manufacturing the fuel cell includes a first process for measuring each of a plurality of frequency AC impedances in a plurality of regions of a first membrane electrode assembly equipped with a first electrode containing a first electrolyte manufactured under given manufacturing conditions, a second process for estimating a distribution of the first electrolyte in a thickness direction of the first electrode based on an AC impedance of each frequency measured respectively to each regions in the first membrane electrode assembly, and a third process, in case, among regions in the first membrane electrode assembly, a first region which is not the desired distribution aimed at the distribution estimate result of the first electrolyte in the second process exists, manufacturing a second electrode containing second electrolyte by adjusting manufacturing conditions to a region corresponding to the first region based on the distribution estimate result of the first region. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a fuel cell.

  A fuel cell including an electrolyte in an electrode is known (see Patent Document 1 below).

Japanese Patent Laying-Open No. 2005-071882

  By the way, in the thickness direction, there has been a demand for manufacturing a fuel cell including an electrode whose distribution state of electrolyte is a distribution state intended by the manufacturer.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell including an electrode whose distribution state of electrolyte is intended in the thickness direction.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
According to one aspect of the present invention, a method for manufacturing a fuel cell is provided. The fuel cell manufacturing method includes a first method of measuring AC impedances of a plurality of frequencies in a plurality of regions of a first membrane electrode assembly including a first electrode including a first electrolyte manufactured under predetermined manufacturing conditions. And a step of estimating a distribution of the first electrolyte in the thickness direction of the first electrode based on the alternating current impedance at each frequency measured for each region in the first membrane electrode assembly And a step of manufacturing a second electrode including a second electrolyte, and the distribution state intended by the distribution estimation result of the first electrolyte in the second step among the regions in the first membrane electrode assembly In the case where there is a non-first region, the first region is set so that the distribution of the second electrolyte in the thickness direction is in the intended distribution state based on the distribution estimation result of the first region. And a third step of manufacturing the second electrode by adjusting the manufacturing conditions with respect to the region corresponding to the region. According to the fuel cell manufacturing method of this embodiment, it is possible to manufacture a fuel cell including an electrode whose distribution state of electrolyte in the thickness direction is intended.

[Application Example 1]
A method for manufacturing a fuel cell, comprising: measuring a plurality of alternating current impedances at a plurality of frequencies in a plurality of regions of a first membrane electrode assembly including a first electrode including a first electrolyte manufactured under predetermined manufacturing conditions. And estimating the distribution of the first electrolyte in the thickness direction of the first electrode based on the AC impedance at each measured frequency for each region in the first membrane electrode assembly. 2 steps and a step of manufacturing a second electrode including a second electrolyte, the distribution of which the distribution estimation result of the first electrolyte in the second step is intended among the respective regions in the first membrane electrode assembly When there is a first region that is not, the second electric power is adjusted by adjusting the manufacturing condition for the region corresponding to the first region based on the distribution estimation result of the first region. A third step of producing, and summarized in that comprises a.

  According to the manufacturing method of the said structure, the fuel cell provided with the electrode which is the distribution state which the distribution state of the electrolyte in the thickness direction intends can be manufactured.

[Application Example 2]
The manufacturing method according to Application Example 1, wherein the manufacturing condition includes a drying condition in a manufacturing process of the third electrode.

  In this way, it is possible to easily manufacture a fuel cell including an electrode in which the distribution state of the electrolyte in the thickness direction is the intended distribution state.

[Application Example 3]
In the manufacturing method according to Application Example 1 or Application Example 2, the third step includes a step of preparing a solvent capable of dissolving the second electrolyte, a catalyst-supporting carrier, and a base material, and the second electrolyte. A step of creating a catalyst ink from the solvent and the catalyst-carrying carrier, a step of applying the catalyst ink to the base material to create a layered ink, and the first membrane electrode assembly In each region, when there is a first region where the distribution estimation result of the first electrolyte in the fourth step is not an intended distribution, the distribution estimation is performed for a region corresponding to the first region of the layered ink. And a fourth step of adjusting and drying the drying conditions based on the results.

  In this way, it is possible to manufacture a fuel cell including an electrode in which the distribution state of the electrolyte in the thickness direction is the intended distribution state.

[Application Example 4]
In the manufacturing method according to Application Example 3, the drying conditions include: a drying temperature on a drying surface to be dried, a wind speed on the drying surface, and a speed on the drying surface in a region corresponding to the first region in the layered ink. A manufacturing method comprising at least one of relative humidity.

  In this way, it is possible to easily manufacture a fuel cell including an electrode in which the distribution state of the electrolyte in the thickness direction is the intended distribution state.

[Application Example 5]
In the manufacturing method according to any one of Application Example 1 to Application Example 4, the first step includes a step of detecting a complex impedance plot based on the AC impedance at each frequency, and based on the complex impedance plot. Estimating the distribution of the first electrolyte in the thickness direction of the first electrode.

  In this way, the distribution state of the electrolyte in the thickness direction can be accurately estimated.

[Application Example 6]
In the manufacturing method according to any one of Application Example 1 to Application Example 5, in the second step, the first gas at each frequency is in a state where an inert gas is introduced into the first electrode of the first membrane electrode assembly. A manufacturing method characterized by measuring an alternating current impedance of one membrane electrode assembly.

  In this way, the distribution state of the electrolyte in the thickness direction can be accurately estimated.

[Application Example 7]
The manufacturing method according to any one of Application Example 1 to Application Example 6, including a step of manufacturing a second membrane electrode assembly using the second electrode.

  If it does in this way, the 2nd membrane electrode assembly as a manufacturer's intent can be manufactured.

[Application Example 8]
8. The manufacturing method according to any one of application examples 1 to 7, wherein the second electrode is a cathode.

  In this way, it is possible to manufacture a cathode in which the distribution state of the electrolyte in the thickness direction is the intended distribution state.

  The present invention can also be realized in other aspects of the method invention, such as a method for manufacturing a membrane electrode assembly or a method for manufacturing a fuel cell electrode, in addition to the method for manufacturing a fuel cell described above. Further, the present invention is not limited to the aspect of the method invention, and can be realized as an aspect of the apparatus invention. Further, aspects as a computer program for constructing those methods and apparatuses, aspects as a recording medium recording such a computer program, data signals embodied in a carrier wave including the computer program, etc. It can also be realized in various ways.

It is a figure which shows schematic structure of the fuel cell CL in the fuel cell as one Example of this invention. It is a flowchart which shows the manufacturing method of the fuel cell CL in an Example. It is a flowchart which shows the manufacturing method of MEA. It is a figure which shows a mode that the layered ink S is formed on the base material K, and it is made to dry. It is a figure which shows the mode of the connection of the state estimation apparatus 10 and fuel cell which are used by a present Example. It is a figure which shows the cyclic voltammogram of a fuel cell. It is a figure which shows the complex impedance plot V. FIG. FIG. 6 is an enlarged view of the vicinity of a turning point P in a complex impedance plot V. It is a flowchart which shows the manufacturing method of new MEA. 6 is a diagram illustrating an example of drying conditions in the layered ink S. FIG.

Hereinafter, embodiments of the present invention will be described based on examples.
A. Example:
A1. Fuel cell configuration:
FIG. 1 is a diagram showing a schematic configuration of a fuel cell CL in a fuel cell as one embodiment of the present invention. The fuel cell of the present embodiment is a solid polymer type fuel cell, and generates power using an oxidizing gas (for example, air) and a fuel gas (for example, hydrogen). The fuel cell includes a plurality of fuel cells CL, two end plates (not shown), two terminals (not shown), and two insulators (not shown). The fuel cell has a stack structure in which a plurality of fuel cells CL are sandwiched between terminals and insulators, and the sandwich structure is sandwiched between two end plates. Further, the fuel cell has a structure in which each fuel cell CL is fastened with a predetermined force in the stacking direction by connecting a tension plate (not shown) to each end plate by a bolt (not shown). ing.

  As shown in FIG. 1, the fuel battery cell CL includes a membrane electrode assembly 5 (hereinafter, referred to as MEA (Membrane Electrode Assembly) 5), separators 6 and 7, and a seal member 110.

  The MEA 5 includes an electrolyte membrane 11, a cathode 12 and an anode 13 disposed on both surfaces of the electrolyte membrane 11, a gas diffusion layer 14 disposed on the outer surface of the cathode 12, and a gas diffusion disposed on the outer surface of the anode 13. Layer 15.

  The electrolyte membrane 11 is a proton conductive ion exchange membrane formed of a fluorine-based resin that is a solid polymer material, and exhibits good proton conductivity in a wet state. The electrolyte membrane 11 is not limited to the fluorine resin, and may be composed of, for example, a hydrocarbon resin.

  The cathode 12 and the anode 13 are composed of a carrier (for example, carbon) supporting a catalyst metal (for example, platinum (Pt)) and an electrolyte (for example, a fluorine resin). Note that the electrolyte contained in the cathode 12 or the anode 13 is not limited to the fluorine-based resin, and may be composed of, for example, a hydrocarbon-based resin.

  The gas diffusion layers 14 and 15 are conductive carbon porous members, and are formed of, for example, carbon cloth or carbon paper.

  A direction in which the members are stacked in the fuel cell CL is also referred to as a stacking direction. The stacking direction is the same direction as the thickness direction of each member of the fuel cell CL. Moreover, it is a direction perpendicular | vertical to a lamination direction (thickness direction), and the direction along the surface of each member of the fuel cell CL is also called a surface direction.

  The separators 6 and 7 can be formed of a gas-impermeable conductive member, for example, dense carbon that has been made to be gas-impermeable by compressing carbon, or a press-molded metal plate. The separator 6 has an uneven shape in which convex portions 18a and concave portions 18b are alternately formed on one side. In the separator 6, the convex portion 18 a presses the gas diffusion layer 14 (cathode 12 or the electrolyte membrane 11), and the concave portion 18 b is between the gas diffusion layer 14 and the gas diffusion layer 14 (cathode 12). An in-cell flow path 18 is formed to supply and discharge oxidizing gas. The separator 7 has an uneven shape in which convex portions 19a and concave portions 19b are alternately formed on one side. In the separator 7, the convex portion 19 a presses the gas diffusion layer 15 (the anode 13 or the electrolyte membrane 11), and the concave portion 19 b is between the gas diffusion layer 15 and the fuel gas with respect to the gas diffusion layer 15 (anode 13). In-cell flow path 19 is formed to supply and discharge the gas.

  The separators 6 and 7 are provided with holes 103 to 106 at positions corresponding to each other near the outer periphery thereof. When the fuel cells are assembled by laminating the separators 6 and 7 together with the MEA 5 and the gas diffusion layers 14 and 15, the holes provided in the corresponding positions of the laminated separators 6 and 7 overlap each other, and the stacking direction A flow path penetrating the inside of the fuel cell is formed. Specifically, the hole 103 forms an oxidizing gas supply manifold, the hole 104 forms an oxidizing gas discharge manifold, the hole 105 forms a fuel gas supply manifold, and the hole 106 is a fuel. A gas exhaust manifold is formed. The oxidizing gas supply manifold is a channel for introducing oxidizing gas into the in-cell channel 18, and the oxidizing gas discharge manifold is a channel for discharging oxidizing gas from the in-cell channel 18. The fuel gas supply manifold is a flow path for introducing fuel gas into the in-cell flow path 19, and the fuel gas discharge manifold is a flow path for discharging fuel gas from the in-cell flow path 19.

  In the fuel cell CL, the seal member 110 is disposed around the in-cell flow path 18, the in-cell flow path 19, and the respective manifolds, and the in-cell flow path 18, the in-cell flow path 19 and the above-mentioned respective flow paths. Ensure the gas seal of the manifold.

A2. Manufacturing method of fuel cell CL:
A method for manufacturing the fuel cell CL in the fuel cell of the present embodiment will be described below. The manufacturing method of the fuel cell CL is performed by a predetermined manufacturer.

  FIG. 2 is a flowchart showing a method for manufacturing the fuel cell CL in the present embodiment. In the manufacturing method of the fuel cell CL in the present embodiment, the manufacturer first manufactures the MEA (Step S10).

  FIG. 3 is a flowchart showing a method for manufacturing the MEA. FIG. 4 is a diagram illustrating a state in which the layered ink S is formed on the substrate K and dried. In the MEA manufacturing process, as shown in FIG. 3, first, an electrolyte (for example, fluorine-based resin), a solvent (for example, water, alcohol, etc.), a catalyst-supported carrier (for example, platinum-supported carbon), Teflon ( A base material K made of (registered trademark) is prepared (FIG. 3: step S110).

  Next, the electrolyte, the solvent, and the catalyst-supporting carrier are mixed to prepare a catalyst ink (FIG. 3: step S120). The catalyst ink is applied onto the substrate K by a decal method to form a layered ink S as shown in FIG. 4 (FIG. 3: step S130).

  Subsequently, the layered ink S is divided into three regions (region Qc1, region Qc2, and region Qc3) as shown in FIG. 4 (step S135).

  For each region (region Qc1, region Qc2, and region Qc3) of the layered ink S, hot air generators KS1, KS2, and KS3 are respectively disposed. Then, using a hot air generator corresponding to each region of the layered ink S, hot air is flowed and dried for each region to manufacture a cathode (FIG. 3: step S140). When drying the layered ink S, the drying surface SA to be dried is selected, and the temperature of the hot air on the drying surface SA and the wind speed of the hot air on the drying surface SA are adjusted for each region. In this case, for example, the temperature of the hot air flowing from each of the hot air generators KS1, KS2, and KS3 or the wind speed of the hot air is set to the same condition. The dry surface SA is the surface opposite to the surface in contact with the substrate K in the layered ink S.

  Next, an anode and an electrolyte membrane are prepared (FIG. 3: Step S150), and the MEA is manufactured by sandwiching the electrolyte membrane between the manufactured cathode and anode (Step S160). In this case, since the cathode (layered ink) is transferred to the electrolyte membrane together with the substrate K, the dry surface SA is in contact with the electrolyte membrane. Hereinafter, in the cathode (layered ink S), the opposite surface of the drying surface SA is also referred to as a drying surface opposite surface SB. In the manufactured MEA, regions corresponding to the cathode region Qc1, the region Qc2, and the region Qc3 are also referred to as a region Q1, a region Q2, and a region Q3, respectively.

  Next, as shown in FIG. 2, using the manufactured MEA, a fuel cell that can introduce gas independently into each of the regions Q1, Q2, and Q3 of the MEA is manufactured (step S20). Specifically, a separator that is different from the separators 6 and 7 and that can introduce gas independently into each region Q1, region Q2, and region Q3 of the MEA and a seal member 110 were prepared and manufactured. The fuel cell is manufactured by disposing the seal member 110 around the MEA and sandwiching them with a prepared separator.

  In the manufactured fuel cell, nitrogen as an inert gas and hydrogen as an active gas are sealed in the cathode and anode regions Q1 to Q3, respectively. And the alternating current impedance in a several frequency is measured for every area | region in MEA of a fuel cell using the state estimation apparatus 10 (step S30). This will be specifically described below.

  FIG. 5 is a diagram illustrating a state of connection between the state estimation device 10 and the fuel cell used in the present embodiment. First, as shown in FIG. 5, in the manufactured fuel battery cell (separator), the wiring 20 and the sensing wire 30 connected to the state estimation device 10 are connected to the portion corresponding to the MEA region where the AC impedance is to be measured. The state estimation device 10 causes a plurality of frequency alternating currents to flow through the fuel cell via the wiring 20, measures the voltage of the fuel cell via the sensing wire 30, and in the region where the sensing wire 30 of the MEA is connected. In contrast, the AC impedance at each frequency is measured. These steps are performed for each region of the MEA, and the AC impedance at each frequency is measured for each region of the MEA. FIG. 5 shows how AC impedance is measured in the MEA region Q1. Note that when AC impedance is measured in a predetermined area of the MEA, nitrogen and hydrogen are not sealed in the cathode and anode in other areas of the MEA. As the hydrogen and nitrogen introduced into the fuel cell, a low humidified gas is used. For example, the relative humidity of hydrogen and nitrogen introduced into the fuel cell is preferably in the range of 0.1 to 60%, and particularly preferably in the range of 10 to 20%. In this embodiment, the temperature of hydrogen and nitrogen introduced into the fuel battery cell is about 23 ° C.

  FIG. 6 is a diagram showing a cyclic voltammogram of the fuel cell. The vertical axis represents current [A], and the horizontal axis represents voltage [V]. In the step S30, the state estimating device 10 applies an electric double layer region (about 0.3 to 0) of a cyclic voltammogram as shown in FIG. Adjust the current so that the voltage is within 5V).

  Next, the complex impedance plot V is detected for each region of the MEA for the manufactured fuel cell (step S40). The complex impedance plot V will be described with reference to FIG. The complex impedance plot is also called a Cole-Cole plot.

  FIG. 7 is a diagram showing a complex impedance plot V. In FIG. In FIG. 7, the vertical axis represents the imaginary part value Z2 of the AC impedance, and is hereinafter also referred to as an imaginary part axis, and the horizontal axis represents the real part value Z1 of the AC impedance. Also called an axis. This complex impedance plot V is a plane formed by the imaginary part axis and the real part axis (hereinafter also referred to as a complex plane), and the real part value Z1 and the imaginary value of the AC impedance at each frequency measured in the step S30. The relationship with the part value Z2 is shown. Specifically, the complex impedance plot V is an approximate curve based on points (hereinafter also referred to as impedance measurement points) representing the real part value Z1 and the imaginary part value Z2 of the AC impedance at each detected frequency in the complex plane. . The imaginary part axis and the real part axis are orthogonal. In each axis, each scale has the same size. That is, in FIG. 7, when the value of the complex impedance plot V changes by the same amount in each of the real part axis and the imaginary part axis, the position on the axis changes by the same amount. In FIG. 7, the solid line indicates the complex impedance plot V, and the black square indicates the impedance measurement point. In FIG. 7, the turning point P is shown in the complex impedance plot V.

The turning point P shown in FIG. 7 is a boundary point at which the property of the function changes in the complex impedance plot V. That is, in the complex impedance plot V, the region that is greatly affected by the ionic conduction resistance of the cathode 12 and the ionic conduction resistance. It is a boundary point with a region that is hardly affected by the. In other words, the turning point P is a point in the complex impedance plot V where the slope of the tangent line (the amount of change of the imaginary part value Z2 with respect to the real part value Z1) is equal to or greater than a predetermined threshold value. This threshold value is set in advance based on a specific design of the fuel cell, for example, the following (i) to (iii).
(I) Production method of cathode in fuel cell (catalyst ink dispersion method, coating method, etc.).
(Ii) The type, amount, thickness direction and surface direction distribution of the electrolyte in the cathode.
(Iii) The type and particle size of the catalyst support in the cathode.

  Subsequently, based on the complex impedance plot V of each region of the MEA detected in step S40, the thickness of each cathode region (region Qc1, Qc2, Qc3) in the manufactured fuel cell (MEA) is determined. The directional electrolyte distribution is estimated (step S50).

  FIG. 8 is an enlarged view of the vicinity of the turning point P in the complex impedance plot V. FIG. When estimating the electrolyte distribution in the thickness direction of the cathode, in the complex impedance plot V, the angle formed by a tangent at a predetermined point on the high frequency side of the turning point P and a line segment parallel to the real part axis. Estimate based on the angle θ. Specifically, estimation is performed based on the following idea.

  That is, when the angle θ is within the range of 45 ° ± α (α: error constant), the ion conduction resistance of the electrolyte is considered to be substantially equal in the thickness direction of the cathode, and the angle θ is greater than 45 ° + α. When the angle θ is larger, it is considered that the ion conduction resistance of the electrolyte on the electrolyte membrane side is low in the thickness direction of the cathode. On the other hand, when the angle θ is smaller than 45 ° −α, the thickness of the cathode In the direction, it is considered that the ionic conduction resistance of the electrolyte membrane on the electrolyte membrane side is high. The error constant α may be a minute positive value, and takes a value in the range of 0.1 to 1, for example.

  Therefore, when the angle θ is within the range of 45 ° ± α, it is estimated that the electrolyte is distributed substantially uniformly in the thickness direction of the cathode, and the angle θ is larger than 45 ° + α. In the thickness direction of the cathode, it is estimated that more electrolyte is distributed on the dry surface SA side than on the dry surface opposite surface SB side, and when the angle θ is smaller than 45 ° −α, the cathode In the thickness direction, it is estimated that more electrolyte is distributed on the dry surface opposite surface SB side than on the dry surface SA side. The “high frequency side from the turning point P” refers to a range of 10 Hz to 1 kHz, for example.

  Next, based on the electrolyte distribution in each region (region Qc1, Qc2, Qc3) estimated in the process of step S50, whether or not the MEA cathode (each region) of the manufactured fuel cell is intended. Is determined (step S60). For example, when it is desired to manufacture a fuel cell in which the electrolyte is distributed substantially uniformly in the thickness direction in each region of the cathode (regions Qc1, Qc2, Qc3), the estimation result of the electrolyte distribution in each region is the thickness of the cathode. If it is estimated that the electrolyte is distributed substantially uniformly in the direction, it is determined that the intended fuel cell has been manufactured (step S60: Yes). On the other hand, when it is desired to manufacture a fuel cell in which the electrolyte is distributed substantially uniformly in the thickness direction in each region of the cathode (regions Qc1, Qc2, Qc3), a predetermined region among the estimation results of the electrolyte distribution in each region In the thickness direction of the cathode, it is estimated that the electrolyte is not distributed substantially uniformly, for example, more distributed on the drying surface opposite surface SB side than on the drying surface SA side. It is determined that the intended fuel cell has not been manufactured (step S60: No).

  If it is determined in step S60 that the MEA cathode of the manufactured fuel cell is not intended (step S60: No), a new MEA is manufactured (step S70). The process of step S70 is a characteristic part in the present invention, and a new MEA manufacturing method will be specifically described with reference to FIG.

  FIG. 9 is a flowchart showing a new MEA manufacturing method. The new MEA manufacturing method shown in FIG. 9 is similar to the MEA manufacturing method in step S10 shown in FIG. 3, and the same step numbers are given to the same steps as in step S10. The description is omitted.

  In the new MEA manufacturing method, as shown in FIG. 9, the layered ink S is formed (step S130), and the layered ink S is divided into three regions (region Qc1, region Qc2, and region Qc3) (step S130). After S135), the drying conditions for the layered ink S are set for each region (regions Qc1, Qc2, Qc3) (step S137A). Specifically, in the step of S60, among the regions of the cathode of the MEA, for the region where the electrolyte distribution in the thickness direction is determined to be intended, the drying conditions of the layered ink S are set in step S10. The same drying conditions as those in step S140 in the MEA manufacturing method of the process are set. Of the regions of the MEA cathode in the step S60, the region in which the electrolyte distribution in the thickness direction is not intended is based on the estimation result of the electrolyte distribution in the thickness direction (see step S50). Set the drying conditions.

  Here, the drying conditions include the selection of the drying surface SA, the temperature of the hot air on the drying surface SA, and the wind speed of the hot air on the drying surface SA in each region of the layered ink S. When it is desired to distribute a large amount of electrolyte on the drying surface SA side in the thickness direction of the cathode, the drying conditions are set as follows. That is, the temperature of the hot air on the drying surface SA is set to be relatively high and / or the speed of the hot air on the drying surface SA is set to be relatively strong so that the drying speed of the solvent from the drying surface SA is increased. In this way, evaporation of the solvent from the drying surface SA can be promoted, the electrolyte is moved to the drying surface SA side along with the evaporation, and a large amount of electrolyte can be distributed on the drying surface SA side as intended. . On the other hand, when it is desired to distribute a large amount of electrolyte on the side opposite to the drying surface SB in the thickness direction of the cathode, the drying conditions are set as follows. That is, the temperature of the hot air on the drying surface SA is set to be relatively low and / or the speed of the hot air on the drying surface SA is set to be relatively weak, and the drying speed of the solvent from the drying surface SA is decreased. If it does in this way, evaporation of the solvent from dry surface SA can be controlled, the movement of the electrolyte accompanying evaporation will be controlled, and many electrolytes can be distributed to the dry surface opposite surface SB side as intended.

  Accordingly, in the process of step S137A, for example, when it is desired to manufacture a fuel cell in which the electrolyte is distributed substantially uniformly in the thickness direction of the cathode, the thickness of each region of the cathode of the MEA is determined in the process of step S60. In the region where the electrolyte distribution in the vertical direction is determined to be unintended, if the estimation result of the electrolyte distribution is estimated that a large amount of electrolyte is distributed on the dry surface opposite surface SB side, the dry surface SA is selected. Then, the temperature of the hot air on the drying surface SA is higher than that at the time of manufacturing the previous fuel cell (see step S140), and / or the air velocity of the hot air on the drying surface SA is set at the time of manufacturing the previous fuel cell ( (See step S140). Also, for example, when it is desired to manufacture a fuel cell in which the electrolyte is distributed substantially uniformly in the thickness direction of the cathode, the electrolyte distribution in the thickness direction of each region of the cathode of the MEA is determined in step S60. If the estimation result of the electrolyte distribution in the region determined to be unintended is estimated that a large amount of electrolyte is distributed on the dry surface SA side, the dry surface SA is selected and hot air on the dry surface SA is selected. Is set to be lower than that at the time of manufacturing the previous fuel cell (see step S140) and / or the wind speed of the hot air on the drying surface SA is set to be lower than that at the time of manufacturing the previous fuel cell (see step S140). To do.

  Subsequently, after the process of step S137A, the hot air generator is adjusted for each area (area Qc1, Qc2, Qc3) of the cathode so as to satisfy the set drying conditions, the layered ink S is dried, and a new cathode is obtained. Is manufactured (step S140A). Then, an anode and an electrolyte membrane are prepared (step S150), and a new MEA is manufactured by sandwiching the electrolyte membrane between the manufactured new cathode and anode (step S160). In this case, since the new cathode is transferred to the electrolyte membrane together with the base material K as in the step S10, the dry surface SA is in contact with the electrolyte membrane.

  After manufacturing a new MEA in the step S70, a new fuel cell is manufactured using the MEA (FIG. 2: step S80). Specifically, a separator and a seal member 110 that can introduce gas independently into each region Q1, region Q2, and region Q3 of the MEA are prepared, and the seal member 110 is disposed around the newly manufactured MEA. A new fuel battery cell is manufactured by sandwiching with a prepared separator. Then, it returns to the process of step S20-step S60, and repeats the process of step S70 and step S80 until the intended fuel cell (MEA) can be manufactured (until it becomes Yes at step S60).

  In the process of step S60, when it is determined that the cathode of the MEA of the manufactured fuel cell is the intended one (step S60: Yes), the same method as that of the last manufactured MEA (step S10 or In step S70, a new MEA is manufactured (step S90). Then, the sealing member 110 is disposed around the newly manufactured MEA, and the fuel cell CL is manufactured by sandwiching them with the separators 6 and 7.

  As described above, in the method of manufacturing the fuel cell according to the present embodiment, in the manufactured fuel cell, the AC impedance (complex impedance plot V) at each frequency for each cathode region (region Qc1, Qc2, Qc3). The electrolyte distribution in the thickness direction of the cathode is estimated based on the above, and if the estimation result of the predetermined region is not the intended distribution state among the estimation results of the electrolyte distribution of each region, the estimation result of the electrolyte distribution is Based on this, the manufacturing conditions (drying conditions) of the region corresponding to the region are adjusted, and a new cathode is manufactured again to manufacture a new fuel cell. In this way, it is possible to control the distribution of the electrolyte in the thickness direction so as to be an intended distribution state. As a result, a fuel cell having a cathode in which the electrolyte distribution is the intended distribution state is manufactured. be able to.

  The fuel cell manufacturing method according to the present embodiment is such that, in the manufactured fuel cell, the electrolyte distribution in the thickness direction in the predetermined region of the cathode regions (regions Qc1, Qc2, Qc3) is not the intended distribution state. In this case, a new drying condition is set based on the drying condition of the layered ink S at the time of the previous fuel cell manufacturing and the estimation result of the electrolyte distribution in the thickness direction in the region. Fuel cell (cathode) is manufactured. In this way, the distribution of the electrolyte in the thickness direction of the cathode can be controlled so as to achieve the intended distribution state.

  In the fuel cell manufacturing method of this embodiment, based on the complex impedance plot V, in detail, a tangent at a predetermined point on the high frequency side of the turning point P in the complex impedance plot V and a line segment parallel to the real part axis. The electrolyte distribution in the thickness direction in the manufactured cathode is estimated on the basis of the angle θ of the angle formed by. In this way, it is possible to accurately estimate the electrolyte distribution in the thickness direction at the cathode without disassembling the manufactured fuel cell.

  In the fuel cell manufacturing method of the present embodiment, when an alternating current is passed through the fuel cell, the voltage in the electric double layer region of the cyclic voltammogram is applied. In this way, the state of the manufactured MEA can be accurately estimated based on the AC impedance at each frequency.

  In the fuel cell manufacturing method of this embodiment, hydrogen and nitrogen introduced into the manufactured fuel cell use gases having a low relative humidity. In this way, the resistance value of the MEA of the manufactured fuel battery cell can be increased, and the complex impedance plot can be suppressed from being linear, and as a result, the electrolyte distribution in the thickness direction of the cathode Can be estimated accurately.

A3. Confirmation test:
FIG. 10 is a diagram showing an example of drying conditions for the layered ink S. FIG. As shown in FIG. 10, the test was performed under the drying conditions 1 to 3 in which the hot air speed on the drying surface SA and the hot air temperature on the drying surface SA were changed. The hot air temperature on the drying surface SA is drying condition 1 = drying condition 2 <drying condition 3 and the hot air wind speed on the drying surface SA is drying condition 1 <drying condition 2 = drying condition 3. Yes.

  As a result of this confirmation test, it was as follows. That is, in the layered ink S, the higher the hot air temperature on the drying surface SA, the larger the angle θ, and the more electrolyte is distributed on the drying surface SA side. In the layered ink S, as the hot air speed on the drying surface SA increases, the angle θ increases and more electrolyte is distributed on the drying surface SA side. Therefore, it can be said that the method of controlling the electrolyte distribution in the thickness direction in the cathode by adjusting the drying conditions as described above in the step S137A is appropriate.

B. Variations:
In addition, elements other than the elements claimed in the independent claims among the constituent elements in each of the above embodiments are additional elements and can be omitted as appropriate. The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

B1. Modification 1:
In the method of manufacturing the fuel cell of the above embodiment, when estimating the electrolyte distribution in the thickness direction of the cathode of the manufactured fuel cell, the tangent at a predetermined point on the high frequency side of the turning point P in the complex impedance plot V And the angle θ formed by the line segment parallel to the real part axis is estimated, but the present invention is not limited to this. For example, in the complex impedance plot V, a straight line obtained by a plurality of points on the high frequency side from the turning point P (for example, a line connecting two points, an approximate straight line of three points, etc.) and a line segment parallel to the real axis The electrolyte distribution in the thickness direction of the cathode may be estimated on the basis of the angle θ of the angle formed in (1). Even if it does in this way, there can exist an effect similar to the said Example.

B2. Modification 2:
In the fuel cell manufacturing method of the above embodiment, when estimating the electrolyte distribution in the thickness direction of the cathode 12, in the complex impedance plot V, the tangent line at a predetermined point on the higher frequency side than the turning point P and the real part axis Is estimated on the basis of the angle θ formed by a line segment parallel to the line segment, but the present invention is not limited to this. For example, a straight line obtained by a plurality of impedance measurement points corresponding to a frequency (for example, 10 Hz to 1 kHz) higher than the frequency corresponding to the turning point P in the complex impedance plot V (for example, a line connecting two points, an approximate straight line of three points) Etc.) and the angle θ formed by the line segment parallel to the real part axis, the electrolyte distribution in the thickness direction of the cathode 12 may be estimated. Even if it does in this way, there can exist an effect similar to the said Example.

B3. Modification 3:
In the fuel cell manufacturing method of the above embodiment, in the manufactured fuel cell, the electrolyte distribution in the thickness direction in each region of the cathode is estimated based on the AC impedance (complex impedance plot V) at each frequency, When the estimation result in the region is not the intended distribution state, a new cathode is newly manufactured based on the estimation result, and a new fuel cell is manufactured. However, the present invention is not limited to this. It is not something that can be done. For example, in the manufactured fuel cell, when the electrolyte distribution in the thickness direction in each region of the anode is estimated based on the AC impedance (complex impedance plot V) at each frequency, and the estimation result is not the intended distribution state Alternatively, based on the estimation result, a new anode may be remanufactured to produce a new fuel cell. In this case, detection of the complex impedance plot V is performed in a state where nitrogen as an inert gas is introduced into the anode of the fuel cell and hydrogen as the active gas is introduced into the cathode. By doing so, it is possible to manufacture a fuel cell having an anode in which the distribution state of the electrolyte in the thickness direction is the intended distribution state.

B4. Modification 4:
In the fuel cell manufacturing method of the above embodiment, the complex impedance plot V is detected with hydrogen as the active gas introduced into the anode of the fuel cell and nitrogen as the inert gas introduced into the cathode. However, the present invention is not limited to this. For example, an inert gas (for example, nitrogen) may be introduced into the anode of the fuel cell, and the complex impedance plot V may be detected in that state. Even if it does in this way, there can exist the effect of the said Example.

B5. Modification 5:
In the fuel cell manufacturing method of the above embodiment, hydrogen and nitrogen introduced into the fuel cell may be gases having a relative humidity higher than 60%. Even in this case, at least part of the effects of the above-described embodiment can be achieved.

B6. Modification 6:
In the fuel cell manufacturing method of the above embodiment, relative humidity on the drying surface SA may be included as a drying condition when the cathode is manufactured and each region of the layered ink S is dried. In this case, instead of flowing hot air over the drying surface SA, a drying accelerator (for example, silica gel or the like) may be disposed on the drying surface SA, and the relative humidity may be adjusted by the amount of the drying accelerator. For example, when it is desired to distribute a large amount of electrolyte on the drying surface SA side in the thickness direction of the cathode, a large amount of drying accelerator is disposed on the drying surface SA. In this way, the evaporation of the solvent from the drying surface SA can be promoted, the electrolyte can be moved to the drying surface SA side along with the evaporation, and a large amount of the electrolyte can be distributed on the drying surface SA side. On the other hand, when it is desired to distribute a large amount of electrolyte on the side opposite to the drying surface SB in the thickness direction of the cathode, the amount of drying accelerator on the drying surface SA is reduced. In this way, evaporation of the solvent from the drying surface SA can be suppressed, movement of the electrolyte accompanying evaporation can be suppressed, and a large amount of electrolyte can be distributed on the drying surface opposite surface SB side.

B7. Modification 7:
In the fuel cell manufacturing method of the above embodiment, when manufacturing a new MEA (cathode), the drying conditions are adjusted for each region based on the estimation result of the electrolyte distribution in the thickness direction in each region of the cathode. Although a new MEA (cathode) is manufactured, the present invention is not limited to this. For example, when manufacturing a new MEA (cathode), on the basis of the estimation result of the electrolyte distribution in the thickness direction in each region of the cathode, for each region, other manufacturing conditions (for example, catalyst ink) A new MEA (cathode) may be manufactured by adjusting the coating conditions. Even if it does in this way, there can exist the effect of the said Example.

B8. Modification 8:
The fuel cell manufacturing method of the above embodiment is performed by a predetermined manufacturer, but the present invention is not limited to this. For example, an automation device may be used instead of the manufacturer. If it does in this way, the intended fuel cell can be manufactured simply by automation.

B9. Modification 9:
In the fuel cell manufacturing method of the above embodiment, the cathode is divided into three regions (region Qc1, region Qc2, and region Qc3), and the electrolyte distribution in the thickness direction is estimated for each region. However, the present invention is not limited to this. For example, the cathode may be divided into two regions, or four or more regions, and the thickness direction electrolyte distribution may be estimated respectively. Even if it does in this way, there can exist the effect of the said Example.

5 ... MEA
DESCRIPTION OF SYMBOLS 6 ... Separator 7 ... Separator 10 ... State estimation apparatus 11 ... Electrolyte membrane 12 ... Cathode 13 ... Anode 14 ... Gas diffusion layer 15 ... Gas diffusion layer 18 ... Cell flow path 30 ... Sensing wire 103 ... Hole 104 ... Hole 105 ... hole 106 ... hole 110 ... seal member K ... base material S ... layered ink V ... complex impedance plot P ... turning point Q1 ... area Z1 ... real part value Q2 ... area Z2 ... imaginary part value Q3 ... area SA ... drying Surface SB ... Dry surface opposite surface CL ... Fuel cell KS1 ... Hot air generator Qc1 ... Region Qc2 ... Region Qc3 ... Region

Claims (8)

A fuel cell manufacturing method comprising:
A first step of measuring AC impedances at a plurality of frequencies in a plurality of regions of a first membrane electrode assembly including a first electrode including a first electrolyte manufactured under predetermined manufacturing conditions;
A second step of estimating the distribution of the first electrolyte in the thickness direction of the first electrode based on the AC impedance at each measured frequency for each region in the first membrane electrode assembly;
A step of manufacturing a second electrode including a second electrolyte, wherein the first electrolyte distribution distribution estimation result in the second step is not the intended distribution state among the regions in the first membrane electrode assembly. When there is a region, based on the distribution estimation result of the first region, the region corresponding to the first region is compared with the region corresponding to the first region so that the distribution of the second electrolyte in the thickness direction is an intended distribution state. A third step of manufacturing the second electrode by adjusting manufacturing conditions;
A manufacturing method comprising: The manufacturing method according to claim 1,
The manufacturing method includes a drying condition of the second electrode . In the manufacturing method of Claim 2 ,
The third step includes
Preparing a solvent capable of dissolving the second electrolyte, a catalyst support, and a base material;
Creating a catalyst ink from the second electrolyte, the solvent, and the catalyst carrier;
Applying the catalyst ink to the substrate to create a layered ink;
Corresponding to the first region of the layered ink when there is a first region that is not the intended distribution state of the first electrolyte distribution estimation result in the fourth step among the regions in the first membrane electrode assembly. A fourth step of adjusting the drying condition of the layered ink based on the distribution estimation result and drying the region to be
The manufacturing method characterized by including. In the manufacturing method of Claim 3,
The drying conditions are:
The region corresponding to the first region in the layered ink includes at least one of a drying temperature on a drying surface to be dried, an air speed on the drying surface, and a relative humidity on the drying surface. Production method. In the manufacturing method in any one of Claims 1 thru | or 4,
The first step includes
Detecting a complex impedance plot based on the AC impedance at each frequency;
Estimating the distribution of the first electrolyte in the thickness direction of the first electrode based on the complex impedance plot;
The manufacturing method characterized by including. In the manufacturing method in any one of Claims 1 thru | or 5,
The second step includes
A manufacturing method, wherein an alternating current impedance of the first membrane electrode assembly at each frequency is measured with an inert gas introduced into the first electrode of the first membrane electrode assembly. In the manufacturing method in any one of Claims 1 thru | or 6,
The manufacturing method characterized by including the process of manufacturing a 2nd membrane electrode assembly using the said 2nd electrode. In the manufacturing method in any one of Claim 1 thru | or 7,
The manufacturing method, wherein the second electrode is a cathode.

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