JP2005222818A - Dismantling method of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dismantling method of a fuel cell capable of surely dismantling the fuel cell at any time in the case of necessity. <P>SOLUTION: First, the fuel cell 10 is positioned and fixed by arranging it so as to inscribe in four positioning blocks 21a protruding on a table face 21. Next, a laser beam is irradiated on an external face of a separator 6 of the fuel cell 10 by a laser beam irradiation device 25. Here, the part laid between an outer peripheral line of an electrode of an MEA and an inner peripheral line of a seal part 8 out of outer faces of the separator 6 of the fuel cell 10 is denoted as a trace line T, and a carriage 23 moves along the trace line T so that the laser irradiation device 25 irradiates laser beam on the trace line T. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell disassembly method.

  Conventionally, as a fuel cell, an electrode assembly in which electrodes are arranged on both sides of an electrolyte, a seal layer disposed around the electrode assembly, and an electrode assembly sandwiched from both sides are bonded through the seal layer. And a pair of separators in which a fuel gas passage is formed on one electrode side and an oxidizing gas passage is formed on the other electrode side. In this type of fuel cell, when hydrogen is supplied as fuel gas to the fuel gas passage and air is supplied as oxidation gas to the oxidation gas passage, hydrogen is divided into protons and electrons at the electrode (anode) facing the fuel gas passage, Among them, protons move to the other electrode (cathode) through the electrolyte, electrons move to the cathode through an external circuit, and oxygen, protons and electrons in the air react at the cathode to produce water. . This reaction generates an electromotive force. Here, the seal layer is a layer of an adhesive that bonds both separators, and plays a role of preventing oxygen and hydrogen from directly contacting each other at the outer peripheral portion of each electrode.

By the way, expensive electrode assemblies (especially electrodes containing precious metal catalysts) are collected from used fuel cells, used fuel cells are separated and discarded, and the performance of used fuel cell electrode assemblies is evaluated. In some cases, it may be desirable to disassemble the fuel cell. For this reason, for example, in Patent Document 1, a linear member is provided between the seal layer of the fuel cell and the separator, and when the fuel cell is disassembled, the linear member is pulled outward to seal the linear cell. The thing which peels a layer and a separator is proposed.
JP 2002-151112 A

  However, in Patent Document 1, although a force from the inside to the outside of the fuel cell is applied between the seal layer and the separator by the linear member and the seal layer and the separator are peeled off, a large force is applied in this direction. Since it is not easy, for example, the linear member is firmly adhered to the seal layer and may not move or the linear member may break, causing a problem that it is difficult to reliably disassemble the fuel cell. .

  An object of the present invention is to provide a fuel cell disassembling method that can be surely disassembled when it is necessary to disassemble the fuel cell.

  The present invention employs the following means in order to achieve at least a part of the above-described object.

The present invention relates to a method of disassembling a fuel cell in which a seal portion is disposed around an electrode assembly in which electrodes are arranged on both sides of an electrolyte, and a pair of separators sandwiching the electrode assembly from both sides are bonded via the seal portion. Because
A disassembly facilitating step for promoting disassembly of the fuel cell by irradiating or injecting a high energy body from the outside of the fuel cell to an outer surface of at least one separator of the pair of separators or a gap between the pair of separators;
Is included.

  According to this fuel cell disassembly method, a high energy body is irradiated or injected from the outside of the fuel cell to the outer surface of at least one separator of the pair of separators or the gap between the pair of separators. Apply to the gap between separators. Therefore, the fuel cell can be reliably disassembled.

  The present invention can be applied to any type of fuel cell, for example, a solid electrolyte membrane type (polymer electrolyte type), solid oxide type, molten carbonate type, phosphoric acid type, alkaline aqueous solution type fuel cell, etc. It is applicable to.

  In the fuel cell disassembly method of the present invention, in the disassembly facilitating step, a portion corresponding to the outer periphery of the electrode on the outer surface of at least one separator of the pair of separators (for example, the outer periphery of the electrode and the inner portion of the seal portion). You may irradiate or inject the said high energy body to the location corresponding to between circumference | surroundings, and the location corresponding to the said seal part. In this way, there is little possibility that the electrode of the electrode assembly is damaged by the high energy body irradiated or jetted.

  In the fuel cell disassembly method of the present invention, in the disassembly facilitating step, the high energy is applied to a portion of the outer surface of at least one separator of the pair of separators corresponding to the space between the outer periphery of the electrode and the inner periphery of the seal portion. The body may be jetted or irradiated. By doing so, the work load can be reduced compared with the case where the operator applies external force to the outer surface of the separator or the gap between the separators using a tool. Here, when irradiating or ejecting the high energy body, a laser beam may be irradiated, a highly compressed fluid may be ejected, or particles having a hardness higher than that of the separator may be ejected. Examples of the laser include solid state lasers such as YAG laser and ruby laser, semiconductor lasers such as gallium arsenide laser, gas lasers such as carbon dioxide laser, helium neon laser, argon laser, and excimer laser. It may be appropriately selected depending on the situation. Examples of the highly compressed fluid include a compressed gas such as compressed air and a high pressure liquid such as high pressure water, and a compressed gas or high pressure liquid to which an abrasive such as dredged sand, metal particles, glass particles, and ceramic particles is added. However, this may be appropriately selected according to the material of the separator. Examples of the high hardness particles include ceramic particles such as alumina ceramic particles and silicon carbide ceramic particles, and metal particles such as steel particles, and these may be appropriately selected according to the material of the separator.

  Next, the best mode for carrying out the present invention will be described below using examples.

[First embodiment]
1A and 1B are explanatory views showing a schematic configuration of a fuel cell 10 according to a first embodiment. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line AA in FIG.

  The fuel cell 10 of the present embodiment is a polymer electrolyte fuel cell, and mainly includes a membrane electrode assembly (hereinafter referred to as MEA) 2 in which electrodes 4 and 5 are disposed on both surfaces of a solid electrolyte membrane 3. The seal portion 8 disposed around the MEA 2 and a pair of separators 6 and 7 bonded to the seal portion 8 with the MEA 2 sandwiched from both sides. The fuel cell 10 is called a single cell and has an electromotive force of about 0.6 to 0.8V. For this reason, for example, when used as a power supply for a drive motor of a vehicle, a direct current power supply of several hundred volts is obtained by closely stacking a large number of fuel cells 10.

  The MEA 2 is obtained by sandwiching a solid electrolyte membrane 3 between two electrodes, that is, an anode 4 that is a fuel electrode and a cathode 5 that is an oxygen electrode. In the MEA 2 of this embodiment, the area of the solid electrolyte membrane 3 is larger than the areas of the anode 4 and the cathode 5. Here, the solid electrolyte membrane 3 is a membrane made of a solid polymer material having good proton conductivity in a wet state. Specifically, the membrane is made of a fluorine-based resin (Nafion membrane manufactured by DuPont). Etc.). The anode 4 and the cathode 5 are constituted by catalyst electrodes 4a and 5a and gas diffusion electrodes 4b and 5b, respectively. The catalyst electrodes 4a and 5a are located on the side in contact with the solid electrolyte membrane 3, and are formed of conductive carbon black carrying platinum fine particles. On the other hand, the gas diffusion electrodes 4b and 5b are formed of carbon cloth laminated on the catalyst electrodes 4a and 5a and woven with yarns made of carbon fibers. The platinum contained in the catalyst electrodes 4a and 5a has an action of promoting the separation of hydrogen into protons and electrons or promoting the reaction of generating water from oxygen, protons and electrons. If it has, you may use things other than platinum. The gas diffusion electrodes 4b and 5b may be formed of carbon paper or carbon felt made of carbon fiber in addition to carbon cloth, and may have sufficient gas diffusibility and conductivity.

  Each of the pair of separators 6 and 7 is formed of a gas-impermeable exothermic conductor, in this embodiment, formed carbon that is compressed by gas to be gas-impermeable, but is formed of a metal such as stainless steel. Also good. Both separators 6 and 7 have fuel gas supply holes 6a and 7a for supplying fuel gas, fuel gas discharge holes 6b and 7b for discharging fuel gas, and an oxidizing gas supply hole for supplying oxidizing gas. 6c, 7c, oxidizing gas discharge holes 6d, 7d for discharging oxidizing gas, refrigerant supply holes 6e, 7e for supplying refrigerant (for example, coolant), and refrigerant discharge hole 6f for discharging refrigerant , 7f. Further, in one separator 6, a fuel gas passage 6g through which fuel gas passes is formed on the surface of the MEA 2 that contacts the anode 4, and a refrigerant passage (not shown) through which the refrigerant passes is formed on the other surface. . Among these, the fuel gas passage 6g is composed of a plurality of concave grooves and communicates with the fuel gas supply hole 6a and the fuel gas discharge hole 6b but does not communicate with other holes. It communicates with the refrigerant discharge hole 6f but does not communicate with other holes. The other separator 7 is formed with an oxidizing gas passage 7g for allowing the oxidizing gas to pass through the surface in contact with the cathode 5 of the MEA 2 and with a coolant passage (not shown) for allowing the coolant to pass through the other surface. Of these, the oxidizing gas passage 7g is constituted by a plurality of concave grooves and communicates with the oxidizing gas supply hole 7c and the oxidizing gas discharge hole 7d but does not communicate with the other holes. It communicates with the refrigerant discharge hole 7f but does not communicate with other holes.

  The seal portion 8 is a layer formed by solidifying an adhesive (for example, an epoxy-based adhesive) over the entire outer periphery of the MEA 2 solid electrolyte membrane 3 where the anode 4 and the cathode 5 are not provided. The seal portion 8 seals a space where the fuel gas surrounded by the solid electrolyte membrane 3 and the separator 6 exists, and seals a space where the oxidizing gas surrounded by the solid electrolyte membrane 3 and the separator 7 exists. The seal portion 8 is provided with through holes in accordance with the positions of the holes 6a to 6f and 7a to 7f provided in the separators 6 and 7, respectively. Further, the seal portion 8 may be formed of a gasket.

  Next, power generation of the fuel cell 10 will be described. In order to generate power in the fuel cell 10, hydrogen humidified as fuel gas is supplied to the fuel gas supply holes 6a and 7a from the outside of the fuel cell 10 and air is supplied as oxidizing gas to the oxidizing gas supply holes 6c and 7c. Then, hydrogen flows from the fuel gas supply hole 6a through the fuel gas passage 6g to the fuel gas discharge hole 6b and then discharged to the outside, and the air is discharged from the oxidation gas supply hole 7c through the oxidation gas passage 7g to the oxidizing gas discharge hole 7d. After flowing to the outside, it is discharged outside. The hydrogen passing through the fuel gas passage 6g is diffused by the gas diffusion electrode 4b of the anode 4 to reach the catalyst electrode 4a, where it is divided into protons and electrons. Among them, protons are transferred to the cathode 5 through the wet solid electrolyte membrane 3, and electrons move to the cathode through an external circuit (not shown). The air passing through the oxidizing gas passage 7g is diffused by the gas diffusion electrode 5b of the cathode 5 and reaches the catalyst electrode 5a. Then, protons, electrons, and oxygen in the air react at the cathode 5 to generate water, and an electromotive force is generated by this reaction. Further, in order to maintain the fuel cell 10 in a temperature range suitable for power generation (for example, 70 to 80 ° C.), the refrigerant is supplied from the outside to the refrigerant supply holes 6e and 7e. The refrigerant is discharged from the refrigerant discharge holes 6f and 7f through a refrigerant passage (not shown) provided in the separators 6 and 7, and is supplied to the refrigerant supply holes 6e and 7e again after the temperature is lowered by a heat exchanger (not shown). . The solid electrolyte membrane 3 of the MEA 2 serves not only to conduct protons, but also serves as an isolation membrane that prevents direct contact between air and hydrogen inside the fuel cell 10. Further, the seal portion 8 prevents air and hydrogen from mixing at the outer peripheral portion of the MEA 2 and prevents these gases from leaking out of the fuel cell 10.

  Next, the disassembling procedure when it becomes necessary to disassemble the fuel cell 10 will be described with reference to FIGS. 2 and 3 are a perspective view and a cross-sectional view showing a state when the fuel cell 10 is irradiated with laser. Here, a laser processing apparatus 20 including a table surface 21 that forms an XY plane, a carriage 23 that moves above the table surface 21 in the XY direction, and a laser irradiation device 25 that is attached to the carriage 23 is used. Assist the disassembly of the fuel cell 10. First, the fuel cell 10 is positioned and fixed on the table surface 21. Since four positioning blocks 21a project from the table surface 21 so as to surround the outline of the fuel cell 10, positioning is performed by arranging the fuel cell 10 so as to be inscribed in the four positioning blocks 21a. And fix. Next, a laser beam oscillated from a laser oscillator (not shown) is irradiated from the laser irradiation device 25 to the outer surface of the separator 6 of the fuel cell 10. Here, in the carriage 23, a portion corresponding to the outer surface of the separator 6 of the fuel cell 10 between the outer peripheral line of the electrodes 4 and 5 of the MEA 2 and the inner peripheral line of the seal portion 8 is defined as a trace line T. The laser irradiation device 25 moves so as to irradiate the laser. The movement control of the carriage 23 is performed by a controller (not shown). The laser output is adjusted so that the portion irradiated with the laser beam penetrates the pair of separators 6 and 7 and the solid electrolyte membrane 3. As a result, the separators 6 and 7 are cut across the entire circumference of the fuel cell 10 between the outer peripheral lines of the electrodes 4 and 5 of the MEA 2 and the inner peripheral line of the seal portion 8. Thereafter, the operator removes the separator 6 and takes out and collects the MEA 2 (cut near the outer peripheral line of the electrodes 4 and 5).

  According to the first embodiment described in detail above, the energy is applied by irradiating the outer surface of the separator 6 with the laser beam from the outside of the fuel cell 10, so that the fuel cell is directed from the inside to the outside as in Patent Document 1, for example. Compared with the case where force is applied, relatively large energy is applied to the outer surface of the separator 6. Therefore, the fuel cell 10 can be reliably disassembled. Further, the laser beam is irradiated along the trace line T between the outer peripheral line of the electrodes 4 and 5 of the MEA 2 and the inner peripheral line of the seal portion 8 on the outer surface of the separator 6. 4 and 5 are less likely to be damaged. Furthermore, since the laser beam is used, the work load is lighter and the work noise is smaller than when the operator applies an external force to the outer surface of the separator 6 using a tool.

  In the first embodiment described above, the laser beam is applied to the outer surface of the separator 6 from the outside of the fuel cell 10, but high-pressure water may be injected as a highly compressed fluid instead of the laser beam. That is, a high-pressure water injection nozzle is attached to the carriage 23 instead of the laser irradiation device 25 and high-pressure water is injected along the trace line T on the outer surface of the separator 6 to cut the separators 6 and 7 and the solid electrolyte membrane 3. Good. In this case, the same effect as that of the first embodiment can be obtained. However, depending on the material of the separators 6 and 7, cutting may not be possible with high-pressure water alone. At that time, an abrasive such as dredged sand, metal particles, glass particles, or ceramic particles may be added to the high-pressure water.

  In the first embodiment, the fuel cell 10 is fixed and the laser irradiation device 25 is moved in the XY direction. However, the laser irradiation device 25 is fixed and the fuel cell 10 is moved in the XY direction. Also good. Alternatively, the laser irradiation device 25 may be moved manually.

  Furthermore, in the first embodiment described above, the laser output is adjusted so as to penetrate the separators 6 and 7 and the solid electrolyte membrane 3, but is adjusted so as to penetrate the separator 6 and the solid electrolyte membrane 3 but not penetrate the separator 7. May be. Also in this case, the separator 6 can be removed and the MEA 2 (cut by the outer peripheral lines of the electrodes 4 and 5) can be recovered.

  Furthermore, in the first embodiment described above, the laser beam was irradiated to the corresponding trace line T between the outer peripheral line of the electrodes 4 and 5 of the MEA 2 and the inner peripheral line of the seal portion 8 in the outer surface of the separator 6. Further, the laser beam may be irradiated with a portion corresponding to the seal portion 8 on the outer surface of the separator 6 as a trace line. In this case, even if a part of the seal part 8 adheres to the separators 6 and 7 after the cutting by the laser beam is finished, the adhesion area is small compared to the case where the whole seal part 8 adheres, so that If the force becomes low and the operator uses a tool or the like, the separator 6 can be easily and reliably removed.

  In the first embodiment described above, the laser beam is irradiated on the outer surface of the separator 6 from above the fuel cell 10, but the laser is applied to the gap between the pair of separators 6 and 7, that is, the seal portion 8 from the side of the fuel cell 10. You may irradiate a beam. For example, after irradiating a laser beam over the entire circumference of the fuel cell 10 to the seal portion 8 between the separator 6 and the solid electrolyte membrane 3 from the side of the fuel cell 10, the seal between the separator 7 and the solid electrolyte membrane 3 is applied. The portion 8 may be irradiated with a laser beam over the entire circumference of the fuel cell 10. In this case, the same effect as in the first embodiment can be obtained. In this case, it is preferable to adjust so that the laser beam does not reach the electrodes 4 and 5 of the MEA 2.

[Second Embodiment]
The second embodiment is an example in which disassembly of the fuel cell 10 similar to the first embodiment is promoted by another method. Here, the description of the configuration of the fuel cell 10 and the power generation operation is the same as in the first embodiment, and will be omitted. A disassembly procedure when the fuel cell 10 needs to be disassembled will be described with reference to FIGS. 4 is a cross-sectional view showing a state when shot blasting is performed on the fuel cell 10, FIG. 5 is a cross-sectional view showing a state after shot blasting, and FIG. 6 is a cross-sectional view showing a state where the MEA is taken out after blasting. is there. First, a pair of separators 6 and 7 are sandwiched from both surfaces by protective blocks 31 and 32 having the same area as the electrodes 4 and 5. Thereby, the protection blocks 31 and 32 cover the area portions corresponding to the electrodes 4 and 5 in the separators 6 and 7. In addition, protective blocks 33 and 34 having a thickness capable of covering the gap between the pair of separators 6 and 7 are arranged on the entire circumference of the fuel cell 10. Thereby, the protection blocks 33 and 34 cover the gaps between the separators 6 and 7 over the entire circumference. These protective blocks 31 to 34 are formed of a material having a hardness higher than that of the high hardness particles 30a described later. Next, the injection port of the blast gun 30 is directed to the portion of the fuel cell 10 that is not covered with the protection blocks 31 to 34, and the compressed air 30b including the high hardness particles 30a is injected from the injection port. The blast gun 30 is configured such that particles (high hardness particles) 30a having higher hardness than the carbon separators 6 and 7 and compressed air 30b from an air compressor (not shown) are supplied to the inside, and the two are mixed. In the state which was done, it ejects from the ejection port. Then, the injected high hardness particles 30a collide with the separators 6 and 7 in a state of being accelerated by the compressed air 30b and having high energy. Further, the pressure of the compressed air 30b is set to a value that can destroy the collision portion when the high-hardness particles 30a having increased speed collide with the separators 6 and 7. Accordingly, portions of the separators 6 and 7 where the high hardness particles 30a ejected from the blast gun 30 collide are successively destroyed. And the high hardness particle | grains 30a are injected to all the parts which are not covered with the protection blocks 31-34 among the fuel cells 10. FIG. Then, as shown in FIG. 5, the separators 6 and 7 are in a state of being destroyed leaving an area corresponding to the electrodes 4 and 5. Thereafter, as shown in FIG. 6, the protection blocks 31 to 34 are removed, the separators 6 and 7 are removed, and the MEA 2 (with the seal portion 8 remaining on the outer periphery of the solid electrolyte membrane 3) is taken out and collected.

According to the second embodiment described in detail above, the high-hardness particles 30a are injected from the outside of the fuel cell 10 to the outer surfaces of the separators 6 and 7 as high energy bodies. As compared with the case of applying a force from the inside to the outside, relatively large energy is applied to the outer surfaces of the separators 6 and 7. Therefore, the fuel cell 10 can be reliably disassembled. Further, since the high hardness particles 30a are ejected outside the outer peripheral lines of the electrodes 4 and 5 of the MEA 2 in the outer surfaces of the separators 6 and 7, there is little possibility that the electrodes 4 and 5 of the MEA 2 are damaged by the high hardness particles 30a. However, the work load can be reduced as compared with the case where the operator applies an external force to the outer surfaces of the separators 6 and 7 using a tool.

  In the first and second embodiments described above, the solid electrolyte membrane type (polymer electrolyte type) fuel cell has been described. However, other types of fuel cells, for example, solid oxide type, molten carbonate type, phosphoric acid type, etc. The present invention can be applied in the same manner to fuel cells of the shape, aqueous alkaline solution type and the like. Further, the material of the seal portion 8 and the gaskets 60 and 70 is not particularly limited as long as the sealability can be ensured. For example, engineering plastic, epoxy resin, phenol resin, polyimide resin, fluorine resin (PTFE, PFA, etc.), Examples include unsaturated polyester resins and polypropylene.

  It goes without saying that the present invention is not limited to the above-described embodiments, and can be implemented in various modes as long as they belong to the technical scope of the present invention.

It is explanatory drawing showing schematic structure of a fuel cell, (a) is a top view, (b) is AA sectional drawing. It is a perspective view showing a mode when irradiating a fuel cell with a laser. It is sectional drawing showing a mode when irradiating a fuel cell with a laser. It is sectional drawing showing a mode when performing shot blasting to a fuel cell. It is sectional drawing showing the mode after performing shot blasting to the fuel cell. It is sectional drawing showing a mode when taking out MEA after blasting.

Explanation of symbols

2 ... MEA, 3 ... solid electrolyte membrane, 4 ... anode (electrode), 4a ... catalyst electrode, 4b ... gas diffusion electrode, 5 ... cathode (electrode), 5a ... catalyst electrode, 5b ... gas diffusion electrode, 6 ... separator, 6a ... Fuel gas supply hole, 6b ... Fuel gas discharge hole, 6c ... Oxidation gas supply hole, 6d ... Oxidation gas discharge hole, 6e ... Refrigerant supply hole, 6f ... Refrigerant discharge hole, 6g ... Fuel gas passage, 6h ... Jetty, 6i ... gasket insertion groove, 6k ... gasket insertion groove, 7 ... separator, 7a ... fuel gas supply hole, 7b ... fuel gas discharge hole, 7c ... oxidation gas supply hole, 7d ... oxidation gas discharge hole, 7e ... refrigerant supply hole, 7f ... refrigerant discharge hole, 7g ... oxidizing gas passage, 8 ... seal part, 10 ... fuel cell, 20 ... laser processing device, 21 ... table surface, 21a ... positioning block, 23 ... carriage, 25 ... laser irradiation device, 30 Blast gun, 30a ... high hardness particles, 30b ... compressed air, 31 to 34 ... protection block.

Claims (7)

A method of disassembling a fuel cell in which a seal portion is disposed around an electrode assembly in which electrodes are arranged on both surfaces of an electrolyte, and a pair of separators sandwiching the electrode assembly from both surfaces are bonded via the seal portion,
A disassembly facilitating step for promoting disassembly of the fuel cell by irradiating or injecting a high energy body from the outside of the fuel cell to an outer surface of at least one separator of the pair of separators or a gap between the pair of separators;
A method for disassembling a fuel cell.   2. The fuel cell disassembly method according to claim 1, wherein in the disassembly promotion step, the high energy body is irradiated or injected to a portion corresponding to an outer periphery of the electrode on an outer surface of at least one separator of the pair of separators.   The step of disassembling promotes or irradiates the high energy body to a portion corresponding to between the outer periphery of the electrode and the inner periphery of the seal portion, of the outer surface of at least one separator of the pair of separators. The fuel cell disassembling method according to claim 1.   2. The fuel cell disassembly method according to claim 1, wherein in the disassembly promotion step, the high energy body is injected or irradiated to a portion corresponding to the seal portion on an outer surface of at least one separator of the pair of separators.   5. The fuel cell disassembly method according to claim 1, wherein, in the disassembly facilitating step, a laser beam is irradiated from the outside of the fuel cell to an outer surface of at least one separator of the pair of separators.   The fuel cell disassembly method according to any one of claims 1 to 4, wherein, in the disassembly facilitating step, a highly compressed fluid is injected from an outside of the fuel cell onto an outer surface of at least one separator of the pair of separators.   The method of disassembling a fuel cell according to any one of claims 1 to 6, wherein, in the disassembly facilitating step, particles having a hardness higher than that of the separator are injected from the outside of the fuel cell onto an outer surface of at least one separator of the pair of separators. .

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