Activation method and device for electrolyte membrane-electrode assembly

Abstract

To provide an activation method for an electrolyte membrane-electrode structure and an activation device thereof, capable of imparting moisture to the electrolyte membrane-electrode structure while avoiding the occurrence of flooding.SOLUTION: An electrolyte membrane-electrode structure (10) is sandwiched between a first jig (42) and a second jig (44). The first jig in which an anode side passage (48) is formed is provided with a first heat pipe (70). The first heat pipe exchanges heat with a first wet gas circulating through the anode side passage. The second jig in which a cathode side passage is formed is provided with a second heat pipe (82). The second heat pipe exchanges heat with a second wet gas circulating through the cathode side passage. Heat is supplied from a heat supply part to the first heat pipe and the second heat pipe.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for activating a membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode that constitute a fuel cell, and also to an activation device for activating the membrane electrode assembly. [Background technology]

[0002] In recent years, fuel cell vehicles (FCVs) equipped with fuel cells have been attracting attention as vehicles with a low environmental impact. Fuel cells generate electricity through an electrochemical reaction between an oxidant gas containing oxygen and a fuel gas containing hydrogen. As can be understood from this, fuel cell vehicles only emit water vapor and do not emit carbon dioxide (CO2), NOx, SOx, etc. In fuel cell vehicles, an electric motor is driven using the electricity generated by the fuel cell. This allows the fuel cell vehicle to run.

[0003] A fuel cell comprises a membrane electrode assembly (MEA). The MEA comprises an electrolyte membrane made of a solid polymer having a first end face and a second end face, an anode electrode provided on the first end face of the electrolyte membrane, and a cathode electrode provided on the second end face of the electrolyte membrane. In other words, the MEA is configured by sandwiching the electrolyte membrane between the anode electrode and the cathode electrode. A unit cell of the fuel cell is assembled by sandwiching the MEA between a pair of separators.

[0004] Immediately after assembly, the water content of the electrolyte membrane of a unit cell is insufficient. Therefore, the unit cell does not provide sufficient power generation performance. To avoid this, the fuel cell is activated before the first operation. Generally, a fuel cell stack made up of multiple unit cells stacked together is activated. In contrast, Patent Document 1 discloses that activation is performed on each individual unit cell. In this case, the activated unit cells are stacked together to assemble a fuel cell stack. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-7006 Summary of the Invention [Problem to be solved by the invention]

[0006] An anode-side flow path is formed in one of the pair of separators. A cathode-side flow path is formed in the other of the pair of separators. During the process of activating the membrane electrode assembly, wet gas may be circulated through the anode-side flow path and the cathode-side flow path. When the wet gas comes into contact with the anode electrode and the cathode electrode, respectively, moisture is imparted to the anode electrode and the cathode electrode.

[0007] If excessive moisture is added to the anode or cathode, a liquid film forms on the anode or cathode, a phenomenon known as flooding. Under these conditions, gas cannot penetrate the electrode catalyst of the anode or cathode, preventing the electrode catalyst from activating.

[0008] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0009] According to one embodiment of the present invention, there is provided a method for activating a membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode that constitute a fuel cell, the method comprising the steps of: a clamping step of clamping the membrane electrode assembly between a first jig, the first jig having an anode-side flow path formed therein for supplying a first wet gas to the anode electrode and a first heat pipe provided therein for transferring heat to and from the first wet gas, and a second jig having a cathode-side flow path formed therein for supplying a second wet gas to the cathode electrode and a second heat pipe provided therein for transferring heat to and from the second wet gas; an activation step of aging the membrane electrode assembly sandwiched between the first jig and the second jig while flowing the first wet gas through the anode-side flow path and the second wet gas through the cathode-side flow path; and In the activation step, a method for activating an electrolyte membrane electrode assembly is provided, in which the temperature of the first wet gas is maintained within a predetermined range by transferring heat between the first wet gas and the first heat pipe, and the temperature of the second wet gas is maintained within a predetermined range by transferring heat between the second wet gas and the second heat pipe.

[0010] According to another embodiment of the present invention, there is provided an activation device for activating a membrane electrode assembly having an electrolyte membrane sandwiched between an anode electrode and a cathode electrode that constitute a fuel cell, comprising: a first jig having an anode-side flow path formed therein for supplying a first wet gas to the anode electrode and a first heat pipe provided therein for exchanging heat with the first wet gas; a second jig having a cathode-side flow path formed therein for supplying a second humid gas to the cathode electrode and a second heat pipe provided therein for exchanging heat with the second humid gas; a first wet gas supply unit that supplies the first wet gas to the anode-side flow path; a second wet gas supply unit that supplies the second wet gas to the cathode-side flow path; a heat supply unit that applies heat to the first heat pipe and the second heat pipe; a control unit that controls heat applied from the heat supply unit to the first heat pipe and the second heat pipe; An activation device is provided comprising: [Effects of the Invention]

[0011] In the present invention, the temperatures of the first and second humid gases are adjusted within a predetermined range by transferring heat between the first heat pipe and the first humid gas and between the second heat pipe and the second humid gas. This maintains the amount of liquid water in the anode flow path and the cathode flow path within an appropriate range. Therefore, moisture can be added to the membrane electrode assembly while preventing flooding. In other words, the present invention enables the membrane electrode assembly to be fully activated.

[0012] The first heat pipe and the second heat pipe have a high response speed to heat input or output, and therefore the temperatures of the first humid gas and the second humid gas can be adjusted quickly. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an enlarged cross-sectional view showing a main part of a membrane electrode assembly sandwiched between a first jig and a second jig. [Figure 2] FIG. 2 is a schematic system diagram of an activation device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic vertical cross-sectional view of the second jig. [Figure 4] FIG. 4 is a schematic cross-sectional view of the first heat pipe. [Figure 5] FIG. 5 is a schematic flow diagram of an activation method according to an embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing the change over time of the cell voltage when flooding is occurring and when flooding is not occurring. [Figure 7] FIG. 7 is a graph showing changes in the amount of liquid water in the anode-side flow channel, changes in the anode-side differential pressure, concentration overpotential of the cell with changes in the amount of liquid water, and changes in the temperature of the wet hydrogen gas. [Figure 8] FIG. 8 is a schematic system diagram of an activation device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] First, a membrane electrode assembly (hereinafter also referred to as "MEA") 10 will be outlined with reference to Fig. 1. In this embodiment, the MEA 10 includes an electrolyte membrane 12 made of a solid polymer. An example of the solid polymer is perfluorosulfonic acid.

[0015] The MEA 10 includes an anode electrode 14 and a cathode electrode 16. The electrolyte membrane 12 is sandwiched between the anode electrode 14 and the cathode electrode 16. The anode electrode 14 has a first electrode catalyst layer 18 containing an electrode catalyst and a first gas diffusion layer 20 for supplying gas to the first electrode catalyst layer 18. The cathode electrode 16 has a second electrode catalyst layer 22 containing an electrode catalyst and a second gas diffusion layer 24 for supplying gas to the second electrode catalyst layer 22. In this case, the MEA 10 includes a resin frame member 26 made of resin that holds the electrolyte membrane 12. However, the resin frame member 26 is not essential.

[0016] In this embodiment, the MEA 10 is not sandwiched between a pair of separators, that is, in this embodiment, activation is performed on the MEA 10, not on the unit cells.

[0017] Next, an activation device 40 according to this embodiment will be described with reference to FIG. 2. The activation device 40 includes a first jig 42, a second jig 44, and a storage case 46. The MEA 10 is sandwiched between the first jig 42 and the second jig 44. The MEA 10, the first jig 42, and the second jig 44 are stored in this state in the storage case 46. The storage case 46 has a first pipe 50 and a second pipe 52 that communicate with an anode-side flow path 48 (see FIG. 1) of the first jig 42, and a third pipe 56 and a fourth pipe 58 that communicate with a cathode-side flow path 54 (see FIG. 1) of the second jig 44. The interior of the storage case 46 is a closed space and is not open to the atmosphere.

[0018] As shown in detail in FIG. 1 , the first jig 42 has a first wavy portion 64 in which first protrusions 60 and first recesses 62 are alternately connected. A recessed space recessed toward the anode 14 is formed between the first recess 62 and the anode 14. This recessed space is the anode-side flow path 48. The first wet gas flowing through the anode-side flow path 48 comes into contact with the anode 14. A first protrusion 66 protruding toward the anode 14 is formed between the first protrusion 60 and the casing 46. A first heat pipe 70 is provided in this first protrusion 66. As shown in FIGS. 2 and 3 , a first electrode terminal 72 is provided on the first jig 42.

[0019] Similarly, the second jig 44 has a second wavy portion 78 in which second protrusions 74 and second recesses 76 are alternately connected (see FIG. 1). A recessed space recessed toward the cathode electrode 16 is formed between the second recess 76 and the cathode electrode 16. This recessed space is the cathode-side flow path 54. The second humid gas flowing through the cathode-side flow path 54 comes into contact with the cathode electrode 16. A second protrusion space 80 protruding toward the cathode electrode 16 is formed between the second protrusions 74 and the accommodating case 46. A second heat pipe 82 is provided in this second protrusion space 80. As shown in FIGS. 2 and 3, a second electrode terminal 84 is provided on the second jig 44.

[0020] As shown in FIGS. 2 and 3 , the housing case 46 is provided with a heat supply unit 86 such as a heater or Peltier element. The heat supply unit 86 provides heat to the first heat pipe 70 and the second heat pipe 82. The configuration of the first heat pipe 70 and the second heat pipe 82 will now be described with reference to the first heat pipe 70, which is schematically shown in FIG. 4 . As shown in FIG. 4 , a closed space 90 is formed inside the first heat pipe 70 along the longitudinal direction of the first heat pipe 70. A working fluid 92, which serves as a heat medium, is stored in this closed space 90. The working fluid 92 is typically water, but may be a liquid other than water. An appropriate amount of the working fluid 92 is sealed in the closed space 90, but does not fill the closed space 90.

[0021] A wick 94 is provided along the longitudinal direction inside the first heat pipe 70. The closed space 90 is divided by the wick 94, thereby forming a main passage 96.

[0022] FIG. 4 shows a state in which heat is applied from the heat supply unit 86 to the first end 70a of the first heat pipe 70. The working liquid 92 to which heat has been applied is vaporized into vapor 100. The vapor 100 moves along the main passage 96 from the first end 70a, which is relatively high temperature, toward the second end 70b, which is relatively low temperature. At the second end 70b, the heat of the vapor 100 is dissipated. As a result, the vapor 100 condenses and returns to the liquid working liquid 92. The working liquid 92 returns to the first end 70a through the inside of the wick 94 due to capillary force. In other words, reflux occurs.

[0023] The second heat pipe 82 is configured similarly to the first heat pipe 70. Inside the second heat pipe 82, the working fluid 92 or vapor 100 moves in the same manner as the working fluid 92 or vapor 100 in the first heat pipe 70.

[0024] As shown in FIG. 2, the activation device 40 includes a first gas line 110. One end of the first gas line 110 is connected to a hydrogen gas supply unit 112 and a nitrogen gas supply unit 114 via a first three-way valve 116. The hydrogen gas supply unit 112 is, for example, a hydrogen gas tank. The nitrogen gas supply unit 114 is, for example, a nitrogen gas tank. In this embodiment, nitrogen gas is used as the inert first gas. The hydrogen gas supply unit 112 and the nitrogen gas supply unit 114 are first gas supply units, and hydrogen gas or nitrogen gas is selectively supplied as the first gas.

[0025] A first humidifying section 118 constituting a first wet gas supply section is provided in the first gas line 110. The first humidifying section 118 adds water vapor to a first gas (hydrogen gas or nitrogen gas). This causes the first gas to become a first wet gas.

[0026] The other end of the first gas line 110 is connected to the first piping 50 of the accommodating case 46. The first wet gas (wet hydrogen gas or wet nitrogen gas) that flows into the first piping 50 from the other end of the first gas line 110 flows through the anode-side flow path 48 formed in the first jig 42.

[0027] The activation device 40 includes a second gas line 120. One end of the second gas line 120 is connected to the second piping 52 of the housing case 46. The other end of the second gas line 120 is connected to a first exhaust line 124 via a first exhaust valve 122. The first wet gas that has flowed through the anode-side flow path 48 passes through the second piping 52 of the housing case 46, the second gas line 120, and the first exhaust valve 122, and is then discharged from the first exhaust line 124. Alternatively, a recovery device (not shown) may be provided in the first exhaust line 124 to recover the first wet gas.

[0028] The activation device 40 includes a third gas line 130. A nitrogen gas supply unit 132 and an oxidizing gas supply unit 134 are connected to one end of the third gas line 130 via a second three-way valve 136. The nitrogen gas supply unit 132 is, for example, a nitrogen gas tank as described above. Nitrogen gas is supplied as an inert second gas. In this embodiment, the nitrogen gas supply unit 114 connected to the first gas line 110 and the nitrogen gas supply unit 132 connected to the third gas line 130 are provided separately. However, one nitrogen gas supply unit may be connected to both the first gas line 110 and the third gas line 130.

[0029] The oxidizing gas supply unit 134 is, for example, a compressor that compresses atmospheric air. Alternatively, the oxidizing gas supply unit 134 may be an oxygen gas cylinder. The nitrogen gas supply unit 132 and the oxidizing gas supply unit 134 are second gas supply units, and nitrogen gas or oxidizing gas is selectively supplied as the second gas.

[0030] A second humidifying section 138 constituting a second wet gas supply section is provided in the third gas line 130. The second humidifying section 138 adds water vapor to the second gas (nitrogen gas or oxidizing gas). This causes the second gas to become a second wet gas (wet nitrogen gas or wet oxidizing gas).

[0031] The other end of the third gas line 130 is connected to the third piping 56 of the accommodating case 46. The second wet gas that flows into the third piping 56 from the other end of the third gas line 130 flows through the cathode-side flow path 54 formed in the second jig 44.

[0032] The activation device 40 includes a fourth gas line 140. One end of the fourth gas line 140 is connected to a fourth pipe 58 of the housing case 46. A second exhaust line 144 is provided at the other end of the fourth gas line 140 via a second exhaust valve 142. The second wet gas that has flowed through the cathode-side flow path 54 passes through the fourth pipe 58 of the housing case 46, the fourth gas line 140, and the second exhaust valve 142, and is then discharged from the second exhaust line 144. Alternatively, a recovery device (not shown) may be provided in the second exhaust line 144 to recover the second wet gas.

[0033] The activation device 40 includes a humidification state acquisition unit 150. In this embodiment, the humidification state acquisition unit 150 includes an electrical parameter detection unit 152 and a control unit 154. The electrical parameter detection unit 152 includes, for example, a first electrode terminal 72, a second electrode terminal 84, and an MEA voltage measurement unit 160. Hereinafter, the voltage of the MEA 10 determined by the MEA voltage measurement unit 160 will be referred to as the cell voltage for convenience. The cell voltage is determined based on the potential difference between the anode electrode 14 and the cathode electrode 16. The electrical parameter detection unit 152 may be an MEA resistance measurement unit, an MEA current measurement unit, or an MEA impedance measurement unit. The electrical parameter detection unit 152 may include all of these measurement units.

[0034] The humidification state acquisition unit 150 further includes a pressure parameter detection unit 161. The pressure parameter detection unit 161 includes an anode differential pressure gauge 162 and a cathode differential pressure gauge 164.

[0035] The anode differential pressure gauge 162 detects the differential pressure between the gas pressure in the first gas line 110 and the gas pressure in the second gas line 120. In other words, this differential pressure represents the differential pressure between the inlet of the anode side flow path 48 to the anode electrode 14 and the outlet of the anode side flow path 48 from the anode electrode 14. The cathode differential pressure gauge 164 detects the differential pressure between the gas pressure in the third gas line 130 and the gas pressure in the fourth gas line 140. In other words, this differential pressure represents the differential pressure between the inlet of the cathode side flow path 54 to the cathode electrode 16 and the outlet of the cathode side flow path 54 from the cathode electrode 16.

[0036] The control unit 154 is electrically connected to the MEA voltage measuring meter 160, the heat supply unit 86, the anode differential pressure meter 162, and the cathode differential pressure meter 164. Information relating to the cell voltage measured by the MEA voltage measuring meter 160 (electrical parameter detection unit 152) is transmitted as an information signal to the control unit 154. Information signals relating to the gas differential pressures measured by the anode differential pressure meter 162 and the cathode differential pressure meter 164, respectively, are also input to the control unit 154.

[0037] As will be described later, in this embodiment, power generation aging is performed. For this purpose, an external load 170 is electrically connected to the MEA 10 via a first jig 42 and a second jig 44.

[0038] Next, an activation method for the MEA 10 according to this embodiment will be described. Fig. 5 shows a schematic flow of the activation method. The activation method includes a clamping step S1, a scavenging step S2, a preparation step S3, an activation step S4, and a re-scavenging step S5. Note that "An" in Fig. 5 indicates the anode electrode 14, and "Ca" in Fig. 5 indicates the cathode electrode 16.

[0039] First, a worker clamps the MEA 10, before it is assembled into a unit cell, between a first jig 42 and a second jig 44. This performs the clamping step S1. Next, the worker places the MEA 10, the first jig 42, and the second jig 44 in a storage case 46. Here, the first pipe 50, the second pipe 52, the third pipe 56, and the fourth pipe 58 of the storage case 46 are pre-connected to the first gas line 110, the second gas line 120, the third gas line 130, and the fourth gas line 140, respectively. In addition, the first electrode terminal 72 of the first jig 42 and the second electrode terminal 84 of the second jig 44 are electrically connected to an external load 170. Although not specifically shown in FIG. 2 , an MEA voltage measuring meter 160 is also electrically connected to the first electrode terminal 72 and the second electrode terminal 84.

[0040] In this state, the operator issues a command signal to "start activation" to the control unit 154. Based on this command signal, the control unit 154 first executes the scavenging step S2.

[0041] In response to the command signal, the control unit 154 operates the first three-way valve 116 in a direction that connects the nitrogen gas supply unit 114 to the first gas line 110, in order to perform the scavenging step S2. The control unit 154 also operates the second three-way valve 136 in a direction that connects the nitrogen gas supply unit 132 to the third gas line 130. The control unit 154 also opens the first exhaust valve 122 and the second exhaust valve 142.

[0042] Nitrogen gas supplied from the nitrogen gas supply unit 114 passes through the first humidifier 118 to become wet nitrogen gas, and then flows through the first gas line 110. The wet nitrogen gas passes through the first piping 50 and flows into the anode-side flow path 48 of the first jig 42. While flowing through the anode-side flow path 48, the wet nitrogen gas comes into contact with the first electrode catalyst layer 18 of the anode 14. This imparts moisture to the anode 14 and the electrolyte membrane 12. After flowing through the anode-side flow path 48, the wet nitrogen gas passes through the second piping 52 and flows into the second gas line 120. The wet nitrogen gas then passes through the first exhaust valve 122 and is discharged from the first exhaust line 124.

[0043] Nitrogen gas supplied from the nitrogen gas supply unit 132 passes through the second humidifier 138 to become wet nitrogen gas, and then flows through the third gas line 130. The wet nitrogen gas flows through the third piping 56 and into the cathode-side flow path 54 of the second jig 44. While flowing through the cathode-side flow path 54, the wet nitrogen gas comes into contact with the second electrode catalyst layer 22 of the cathode electrode 16. This imparts moisture to the cathode electrode 16 and the electrolyte membrane 12. The wet nitrogen gas that has flowed through the cathode-side flow path 54 flows through the fourth piping 58 and into the fourth gas line 140. The wet nitrogen gas then passes through the second exhaust valve 142 and is discharged from the second exhaust line 144.

[0044] As a result of the above, air is discharged from the anode-side flow path 48 and the cathode-side flow path 54 and replaced with wet nitrogen gas. When the control unit 154 recognizes that a predetermined time has elapsed since the start of the scavenging step S2, the process proceeds to the preparation step S3. Specifically, the control unit 154 operates the first three-way valve 116 in a direction that connects the hydrogen gas supply unit 112 to the first gas line 110.

[0045] Hydrogen gas supplied from the hydrogen gas supply unit 112 passes through the first humidifier 118 to become wet hydrogen gas, and then flows through the first gas line 110. The wet hydrogen gas flows through the first piping 50 into the anode-side flow path 48 of the first jig 42. While flowing through the anode-side flow path 48, the wet hydrogen gas comes into contact with the first electrode catalyst layer 18 of the anode 14. Therefore, the addition of moisture to the anode 14 and the electrolyte membrane 12 is continued. After flowing through the anode-side flow path 48, the wet hydrogen gas flows through the second piping 52 into the second gas line 120. The wet hydrogen gas then passes through the first exhaust valve 122 and is discharged from the first exhaust line 124. This wet hydrogen gas may be recovered by a recovery mechanism (not shown).

[0046] In the preparation step S3, cavitation-containing steam (gas-liquid two-phase flow) may be injected into the first gas line 110 and the third gas line 130 using an ultrasonic injection nozzle. In this case, the first electrode catalyst layer 18 and the second electrode catalyst layer 22 are well wetted by the steam. That is, the wetted state of the first electrode catalyst layer 18 and the second electrode catalyst layer 22 is improved.

[0047] When the control unit 154 recognizes that a predetermined time has elapsed since the start of the preparation step S3, the process proceeds to the activation step S4. Specifically, the control unit 154 switches the second three-way valve 136 to block communication between the nitrogen gas supply unit 132 and the third gas line 130 and to connect the oxidant gas supply unit 134 and the third gas line 130. As a result, an oxidant gas (typically compressed air) containing oxygen gas flows into the third gas line 130. The oxidant gas passes through the second humidifier 138 to become a wet oxidant gas, and then flows through the third pipe 56 into the cathode-side flow path 54 of the second jig 44. The wet oxidant gas comes into contact with the second electrode catalyst layer 22 of the cathode electrode 16 while flowing through the cathode-side flow path 54. As a result, the addition of moisture to the cathode electrode 16 and the electrolyte membrane 12 continues. The wet oxidizing gas that has flowed through the cathode-side flow path 54 passes through the fourth piping 58 and flows into the fourth gas line 140. Thereafter, the wet oxidizing gas passes through the second exhaust valve 142 and is discharged from the second exhaust line 144.

[0048] In this case, hydrogen is ionized in the first electrode catalyst layer 18 of the anode electrode 14 to generate protons and electrons. The protons are conducted within the electrolyte membrane 12 and reach the second electrode catalyst layer 22 of the cathode electrode 16. The electrons reach the second electrode catalyst layer 22 of the cathode electrode 16 via the external load 170. In the second electrode catalyst layer 22, oxygen, protons, and electrons chemically combine to generate water.

[0049] The electrochemical reaction described above is an exothermic reaction. That is, the MEA 10 becomes heated. When this heat is transferred to the wet hydrogen gas and the wet oxidant gas, the temperatures of the wet hydrogen gas and the wet oxidant gas rise. At this time, the first heat pipe 70 removes heat from the wet hydrogen gas. Similarly, the second heat pipe 82 removes heat from the wet oxidant gas. In this way, the first heat pipe 70 and the second heat pipe 82 normally cool the wet hydrogen gas and the wet oxidant gas, respectively.

[0050] In Figure 6, the dashed line shows the change in cell voltage over time when flooding is not occurring. As can be seen from Figure 6, the cell voltage when flooding is not occurring changes in a gentle curve. The solid line shows the change in cell voltage over time when flooding is occurring. Flooding occurs because an overvoltage occurs due to a high moisture content (water vapor concentration) in either the anode electrode 14 or the cathode electrode 16, or in both the anode electrode 14 and the cathode electrode 16. Hereinafter, this overvoltage will be referred to as the "cell concentration overvoltage" for convenience.

[0051] Graph A in FIG. 7 shows that the amount of liquid water in the anode-side flow path 48 increases over time. In this case, as shown in graph B in FIG. 7, the pressure difference between the first gas line 110 and the second gas line 120 increases as the amount of liquid water increases. Note that this is represented as the "anode-side pressure difference" in FIG. 7. Also, as shown in graph C in FIG. 7, the concentration overvoltage of the cell increases. Meanwhile, the working fluid 92 in the first heat pipe 70 loses latent heat from the wet hydrogen gas. Therefore, as shown in graph D in FIG. 7, the temperature of the working fluid 92 decreases. Although not specifically shown, graphs A to D similar to those described above can also be obtained when the amount of liquid water in the cathode-side flow path 54 increases over time.

[0052] Point TP in graph C is a preset upper limit. That is, point TP indicates that the concentration overpotential of the cell has reached a predetermined upper limit. At this time, the amount of liquid water in the anode-side flow path 48 has reached the upper limit of the allowable range. If the amount of liquid water increases further, it will become more difficult for hydrogen to reach the first electrode catalyst layer 18. This raises the concern that the anode 14 may not be sufficiently activated.

[0053] In this embodiment, an information signal relating to the concentration overvoltage of the cell is constantly transmitted to the control unit 154. When the control unit 154 recognizes that the concentration overvoltage of the cell has reached a predetermined upper limit, it determines that the humidification state of the MEA 10 is at the appropriate upper limit. In this way, the cell voltage is an index for understanding the humidification state of the MEA 10.

[0054] The control unit 154 further receives as input the differential pressure measured by the anode differential pressure gauge 162 and the differential pressure measured by the cathode differential pressure gauge 164. As described above, the differential pressure measured by the anode differential pressure gauge 162 is the differential pressure between the inlet of the anode electrode 14 in the anode-side flow path 48 and the outlet of the anode electrode 14 in the anode-side flow path 48. The differential pressure measured by the cathode differential pressure gauge 164 is the differential pressure between the inlet of the cathode electrode 16 in the cathode-side flow path 54 and the outlet of the cathode electrode 16 in the cathode-side flow path 54. When the control unit 154 recognizes that either differential pressure has reached a predetermined upper limit, it determines that the humidification state of the MEA 10 is at the appropriate upper limit. In this way, the above differential pressure is also an indicator for understanding the humidification state of the MEA 10.

[0055] Having made the above determination, the control unit 154 increases the temperatures of the first heat pipe 70 and the second heat pipe 82. Specifically, the control unit 154 increases the amount of heat generated by the heat supply unit 86, thereby increasing the amount of heat transferred from the heat supply unit 86 to the first heat pipe 70 and the second heat pipe 82.

[0056] This control increases the amount of heat imparted to the wet hydrogen gas from the first heat pipe 70. Similarly, the amount of heat imparted to the wet oxidant gas from the second heat pipe 82 increases. Therefore, as shown in graph D in FIG. 7, the dew point of the wet hydrogen gas (and the wet oxidant gas) increases. As a result, condensation of the wet hydrogen gas and the wet oxidant gas becomes less likely to occur. This gradually reduces the amount of liquid water in the anode-side flow path 48 and the cathode-side flow path 54, as shown in graph A in FIG. 7. As the amount of liquid water decreases, the concentration overvoltage of the cell decreases, as shown in graph C in FIG. 7. In addition, the differential pressure between the first gas line 110 and the second gas line 120 decreases, as shown in graph B in FIG. 7.

[0057] If the amount of liquid water in each of the anode-side flow path 48 and the cathode-side flow path 54 is excessively reduced, there is a concern that the electrolyte membrane 12 will dry out. Therefore, when the concentration overpotential of the cell reaches a predetermined lower limit, the control unit 154 determines that "the humidification state of the MEA 10 is at the appropriate lower limit." The predetermined lower limit is indicated by point DW on graph C in FIG. 7. The control unit 154 also makes the same determination as above when the differential pressure between the first gas line 110 and the second gas line 120 reaches a predetermined lower limit.

[0058] Having made the above determination, the control unit 154 reduces the temperatures of the first heat pipe 70 and the second heat pipe 82. Specifically, the control unit 154 reduces the amount of heat generated by the heat supply unit 86, thereby reducing the amount of heat transferred from the heat supply unit 86 to the first heat pipe 70 and the second heat pipe 82.

[0059] This control reduces the amount of heat imparted to the wet hydrogen gas from the first heat pipe 70. Similarly, the amount of heat imparted to the wet oxidant gas from the second heat pipe 82 reduces. Therefore, as shown in graph D in FIG. 7, the dew point of the wet hydrogen gas (and the wet oxidant gas) decreases. As a result, condensation of the wet hydrogen gas and the wet oxidant gas becomes more likely. As a result, as shown in graph A in FIG. 7, the amount of liquid water in each of the anode side flow path 48 and the cathode side flow path 54 gradually increases. As the amount of liquid water increases, the concentration overvoltage of the cell increases, as shown in graph C in FIG. 7. Furthermore, as shown in graph B in FIG. 7, the pressure difference between the first gas line 110 and the second gas line 120 increases.

[0060] The first heat pipe 70 and the second heat pipe 82 have a high response speed to the application or cessation of heat application. Therefore, when heat is applied from the heat supply unit 86 to the first heat pipe 70, the temperature of the wet hydrogen gas in the anode-side flow path 48 rises quickly. Similarly, when heat is applied from the heat supply unit 86 to the second heat pipe 82, the temperature of the wet oxidant gas in the cathode-side flow path 54 rises quickly. Conversely, when the application of heat from the heat supply unit 86 to the first heat pipe 70 is stopped, the temperature of the wet hydrogen gas in the anode-side flow path 48 drops quickly. Similarly, when the application of heat from the heat supply unit 86 to the second heat pipe 82 is stopped, the temperature of the wet oxidant gas in the cathode-side flow path 54 drops quickly.

[0061] In this manner, the temperatures of the wet hydrogen gas and the wet oxidant gas are quickly adjusted. That is, the temperatures of the wet hydrogen gas and the wet oxidant gas can be maintained substantially constant. Therefore, the amount of liquid water in each of the anode flow path 48 and the cathode flow path 54 can be maintained at an appropriate level, thereby preventing flooding. As a result, a sufficient amount of wet hydrogen gas reaches the first electrode catalyst layer 18 of the anode electrode 14, and a sufficient amount of wet oxidant gas reaches the second electrode catalyst layer 22 of the cathode electrode 16. This allows the MEA 10 to be sufficiently activated.

[0062] When the control unit 154 recognizes that a predetermined time has elapsed since the start of the activation step S4, it controls the first three-way valve 116 and the second three-way valve 136 to transition to the re-scavenging step S5. Specifically, the control unit 154 controls the first three-way valve 116 to block communication between the hydrogen gas supply unit 112 and the first gas line 110 and to connect the nitrogen gas supply unit 114 and the first gas line 110. The control unit 154 also controls the second three-way valve 136 to block communication between the third gas line 130 and the oxidizing gas supply unit 134 and to connect the third gas line 130 and the nitrogen gas supply unit 132.

[0063] In this state, nitrogen gas is supplied from the nitrogen gas supply unit 114 to the anode-side flow path 48, and from the nitrogen gas supply unit 132 to the cathode-side flow path 54. The nitrogen gas becomes wet nitrogen gas through the same flow path as the nitrogen gas flow path in the scavenging step S2, and is supplied to the anode electrode 14 and the cathode electrode 16. The wet nitrogen gas passes through the second gas line 120 and the fourth gas line 140 and is exhausted from the first exhaust valve 122 and the second exhaust valve 142, respectively. That is, the anode-side flow path 48 and the cathode-side flow path 54 are replaced with wet nitrogen gas.

[0064] This completes the re-scavenging step S5. After that, the first three-way valve 116, the second three-way valve 136, the first exhaust valve 122, and the second exhaust valve 142 are closed, and the MEA 10 is separated from the activation device 40.

[0065] As described above, the present embodiment is a method for activating a membrane electrode assembly (10) in which an electrolyte membrane (12) is sandwiched between an anode electrode (14) and a cathode electrode (16) that constitute a fuel cell, the method comprising: a clamping step (S1) of clamping the membrane electrode assembly between a first jig (42) having an anode-side flow path (48) for supplying a first wet gas to the anode electrode and a first heat pipe (70) for exchanging heat with the first wet gas, and a second jig (44) having a cathode-side flow path (54) for supplying a second wet gas to the cathode electrode and a second heat pipe (82) for exchanging heat with the second wet gas; an activation step (S4) of aging the membrane electrode assembly sandwiched between the first jig and the second jig while flowing the first wet gas through the anode-side flow path and the second wet gas through the cathode-side flow path; and A method for activating an electrolyte membrane electrode assembly is disclosed, in which, in the activation step, the temperature of the first wet gas is maintained within a predetermined range by transferring heat between the first wet gas and the first heat pipe, and the temperature of the second wet gas is maintained within a predetermined range by transferring heat between the second wet gas and the second heat pipe.

[0066] In this embodiment, heat is transferred between the first heat pipe and the first humid gas, and between the second heat pipe and the second humid gas, thereby adjusting the temperatures of the first humid gas and the second humid gas within a predetermined range. This maintains the amount of liquid water in the anode flow path and the cathode flow path within an appropriate range. This allows moisture to be added to the membrane electrode assembly while preventing flooding. In other words, the membrane electrode assembly can be fully activated.

[0067] The first heat pipe and the second heat pipe have a high response speed to heat input or output, and therefore the temperatures of the first humid gas and the second humid gas can be adjusted quickly.

[0068] This embodiment discloses a method for activating an electrolyte membrane electrode assembly, in which an index relating to the humidification state of the electrolyte membrane electrode assembly is acquired by a humidification state acquisition unit (150) in the activation step, and the temperatures of the first heat pipe and the second heat pipe are increased when the index reaches a predetermined threshold value.

[0069] In this case, whether or not to apply heat between the first heat pipe and the first humid gas and the second humid gas is determined based on the index. That is, by obtaining the index, the temperatures of the first humid gas and the second humid gas can be easily adjusted.

[0070] This embodiment discloses a method for activating a membrane electrode assembly, in which the index is obtained based on a change in an electrical parameter or a change in a pressure parameter. Here, the electrical parameter is the voltage value, resistance value, current value, or impedance value of the membrane electrode assembly. The pressure parameter is the differential pressure between a first wet gas supplied to an anode electrode and the first wet gas discharged from the anode electrode. Alternatively, the pressure parameter is the differential pressure between a second wet gas supplied to a cathode electrode and the second wet gas discharged from the cathode electrode.

[0071] For example, when the voltage value of the membrane electrode assembly decreases, when the resistance value or impedance value of the membrane electrode assembly increases, or when the differential pressure increases, it is determined that the amount of liquid water in the anode side flow path and the cathode side flow path is increasing. Therefore, the humidification state of the membrane electrode assembly can be determined by using the electrical parameters of the membrane electrode assembly or the differential pressure as an indicator. When the voltage value of the membrane electrode assembly decreases, or when the resistance value or impedance value of the membrane electrode assembly increases, heat is imparted from the first heat pipe to the first humid gas. Heat is also imparted from the second heat pipe to the second humid gas. As a result, the amount of liquid water in the anode side flow path and the cathode side flow path begins to decrease.

[0072] This embodiment discloses a method for activating an electrolyte membrane electrode assembly, in which the application of heat from the first heat pipe and the second heat pipe to the first humid gas and the second humid gas, respectively, is stopped when the indicator reaches another predetermined threshold.

[0073] By carrying out such control, it is possible to prevent the amount of liquid water in the anode side flow channel and the cathode side flow channel from being reduced excessively, thereby providing sufficient moisture to the membrane electrode assembly.

[0074] The present embodiment relates to an activation device (40) for activating a membrane electrode assembly (10) in which an electrolyte membrane (12) is sandwiched between an anode electrode (14) and a cathode electrode (16) that constitute a fuel cell, the device comprising: a first jig (42) having an anode-side flow path (48) for supplying a first wet gas to the anode electrode and a first heat pipe (70) for exchanging heat with the first wet gas; a second jig (44) in which a cathode-side flow path (54) for supplying a second wet gas to the cathode electrode is formed and in which a second heat pipe (82) for transferring heat to and from the second wet gas is provided; a first wet gas supply unit that supplies the first wet gas to the anode-side flow path; a second wet gas supply unit that supplies the second wet gas to the cathode-side flow path; a heat supply unit (86) that applies heat to the first heat pipe and the second heat pipe; a control unit (154) that controls the heat applied from the heat supply unit to the first heat pipe and the second heat pipe; An activation device comprising:

[0075] With this configuration, the temperatures of the first moist gas and the second moist gas can be quickly adjusted to within a predetermined range.

[0076] This embodiment discloses an activation device including a humidification state acquisition unit (150) that acquires an index relating to the humidification state of the membrane electrode assembly.

[0077] In this case, the control unit determines whether to transfer heat between the first and second heat pipes and the first and second humid gases based on the index. By acquiring the index in this way, the temperatures of the first and second humid gases can be easily adjusted.

[0078] This embodiment discloses an activation device in which the humidification state acquisition unit acquires the index based on a change in an electrical parameter or a change in a pressure parameter. As described above, the electrical parameter is the voltage value, resistance value, current value, or impedance value of the membrane electrode assembly. The pressure parameter is the differential pressure between the first humid gas supplied to the anode electrode and the first humid gas discharged from the anode electrode. Alternatively, the pressure parameter is the differential pressure between the second humid gas supplied to the cathode electrode and the second humid gas discharged from the cathode electrode.

[0079] As described above, the humidification state of the membrane electrode assembly can be determined by using the electrical parameters of the membrane electrode assembly or the differential pressure as an index.

[0080] This embodiment discloses an activation device including a housing case (46) that houses the first jig and the second jig with the membrane electrode assembly sandwiched therebetween.

[0081] By storing the first jig and the second jig sandwiching the electrolyte membrane-electrode assembly in a storage case, it is possible to prevent the first wet gas from leaking from the anode-side flow path of the first jig and the second wet gas from leaking from the cathode-side flow path of the second jig.

[0082] This embodiment discloses an activation device including a voltage application unit (180) that applies a voltage to the membrane electrode assembly.

[0083] According to this configuration, it is possible to activate the membrane electrode assembly by CV aging or hydrogen pump operation.

[0084] The present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

[0085] For example, instead of power generation aging, it is also possible to perform CV aging, hydrogen pump operation, concentration cell operation, etc.

[0086] When performing CV aging, hydrogen pump operation, or the like, a voltage application unit 180 is used instead of the external load 170 (see FIG. 2) as shown in FIG. 8. In this case, the activation device 40A is configured to include the voltage application unit 180. Although not particularly shown, the voltage application unit 180 typically has a potentiostat electrically connected to the MEA 10 and a potential sweeper that controls the potentiostat.

[0087] When CV aging is performed, preferably, a change in the ratio of the output voltage to the applied voltage (output / input ratio) is measured as an electrical parameter.

[0088] A cooling unit may be provided instead of the heat supply unit 86. The heat supply unit 86 or the cooling unit may be provided separately for the anode electrode 14 and the cathode electrode 16. In either case, the heat supply unit 86 and the cooling unit may be provided together. [Explanation of symbols]

[0089] 10...Electrolyte membrane / electrode structure 12...Electrolyte membrane 14...Anode electrode 16...Cathode electrode 40, 40A... Activation device 42... First jig 44...Second jig 46...Storage case 48...Anode side flow path 54...Cathode side flow path 66...First convex space 70...First heat pipe 80... Second convex space 82... Second heat pipe 86...heat supply section 112...hydrogen gas supply section 114, 132...Nitrogen gas supply unit 118...First humidification unit 134...oxidant gas supply unit 138...second humidification unit 150... Humidification state acquisition unit 152... Electrical parameter detection unit 154...Control unit 160...MEA voltage measuring meter 161... Pressure parameter detection unit 162... Anode differential pressure gauge 164...Cathode differential pressure gauge 170...External load 180...Voltage application section

Claims

1. A method for activating an electrolyte membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode that constitute a fuel cell, comprising: a clamping step of clamping the membrane electrode assembly between a first jig, the first jig having an anode-side flow path formed therein for supplying a first wet gas to the anode electrode and a first heat pipe provided therein for transferring heat to and from the first wet gas, and a second jig having a cathode-side flow path formed therein for supplying a second wet gas to the cathode electrode and a second heat pipe provided therein for transferring heat to and from the second wet gas; an activation step of aging the membrane electrode assembly sandwiched between the first jig and the second jig while flowing the first wet gas through the anode-side flow path and flowing the second wet gas through the cathode-side flow path; and A method for activating an electrolyte membrane / electrode structure, wherein the activation process is carried out with the first jig and the second jig sandwiching the electrolyte membrane / electrode structure between them housed in a housing case, and during the activation process, the temperature of the first wet gas is maintained within a predetermined range by exchanging heat between the first wet gas and the first heat pipe, and the temperature of the second wet gas is maintained within a predetermined range by exchanging heat between the second wet gas and the second heat pipe.

2. 2. The activation method for an electrolyte membrane electrode assembly according to claim 1, wherein in the activation step, an index relating to the humidification state of the electrolyte membrane electrode assembly is acquired by a humidification state acquisition unit, and when the index reaches a predetermined threshold, the temperatures of the first heat pipe and the second heat pipe are increased.

3. 3. The activation method according to claim 2, further comprising: acquiring the index based on a change in an electrical parameter or a change in a pressure parameter; the electrical parameter is a voltage value, a resistance value, a current value, or an impedance value of the membrane electrode assembly, a pressure parameter being a differential pressure between the first wet gas supplied to the anode electrode and the first wet gas discharged from the anode electrode, or a differential pressure between the second wet gas supplied to the cathode electrode and the second wet gas discharged from the cathode electrode.

4. 4. The activation method for an electrolyte membrane / electrode assembly according to claim 2 or 3, wherein the application of heat from the first heat pipe and the second heat pipe to the first humid gas and the second humid gas, respectively, is stopped when the indicator reaches another predetermined threshold.

5. An activation device for activating a membrane electrode assembly having an electrolyte membrane sandwiched between an anode electrode and a cathode electrode that constitute a fuel cell, comprising: a first jig having an anode-side flow path formed therein for supplying a first moist gas to the anode electrode and a first heat pipe provided therein for exchanging heat with the first moist gas; a second jig having a cathode-side flow path formed therein for supplying a second humid gas to the cathode electrode and a second heat pipe provided therein for transferring heat to and from the second humid gas; a first wet gas supply unit that supplies the first wet gas to the anode-side flow path; a second wet gas supply unit that supplies the second wet gas to the cathode-side flow path; a heat supply unit that applies heat to the first heat pipe and the second heat pipe; a control unit that controls heat applied from the heat supply unit to the first heat pipe and the second heat pipe; a housing case that houses the first jig and the second jig with the membrane electrode assembly sandwiched therebetween; An activation device comprising:

6. 6. The activation device according to claim 5, further comprising a humidification state acquisition unit that acquires an index relating to the humidification state of the membrane electrode assembly.

7. 7. The activation device according to claim 6, wherein the humidification state acquisition unit acquires the index based on a change in an electrical parameter or a change in a pressure parameter. the electrical parameter is a voltage value, a resistance value, a current value, or an impedance value of the membrane electrode assembly, the pressure parameter is a differential pressure between the first wet gas supplied to the anode electrode and the first wet gas discharged from the anode electrode, or a differential pressure between the second wet gas supplied to the cathode electrode and the second wet gas discharged from the cathode electrode.

8. 8. The activation device according to claim 5, further comprising a voltage application unit that applies a voltage to the membrane electrode assembly.

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