JP5211592B2 - Manufacturing method of fuel cell separator - Google Patents

Description

  The present invention relates to a fuel cell separator, a fuel cell separator manufacturing method, a fuel cell separator manufacturing apparatus, and a fuel cell technology.

  In general, a fuel cell includes an electrolyte membrane, a pair of electrodes (anode electrode and cathode electrode) including a catalyst layer and a diffusion layer, and a pair of fuel cell separators (anode electrode fuel cell separator and cathode electrode) sandwiching the electrodes. Fuel cell separator). At the time of power generation of the fuel cell, when the anode gas supplied to the anode electrode is hydrogen gas and the cathode gas supplied to the cathode electrode is oxygen gas, a reaction to form hydrogen ions and electrons is performed on the anode electrode side. Passes through the electrolyte membrane to the cathode electrode side, and electrons reach the cathode electrode through an external circuit. On the other hand, on the cathode side, hydrogen ions, electrons, and oxygen gas react to generate moisture, and energy is released.

  In general, a separator for a fuel cell is formed with a reaction gas channel (an anode gas supply channel or a cathode gas supply channel) for supplying a reaction gas (hydrogen gas or oxygen gas) to an electrode. A part of the water generated from the cathode electrode side during power generation of the fuel cell is usually drained out of the fuel cell system from the cathode gas supply path (or anode gas supply path) of the fuel cell separator. However, when the amount of water generated from the cathode electrode side increases, the water stays in the fuel cell separator (cathode gas supply path or anode gas supply path). If moisture stays in the fuel cell separator (cathode gas supply path or anode gas supply path), the supply of the reaction gas to the cathode electrode (also the anode electrode) is hindered, and the power generation performance of the fuel cell is reduced.

  Accordingly, improvements have been made to improve the drainage of the fuel cell separator so that moisture does not stay in the fuel cell separator and cause a decrease in the power generation performance of the fuel cell.

  For example, Patent Document 1 proposes a fuel cell separator in which a hydrophilic group is formed by subjecting the fuel cell separator to a hydrophilic treatment such as plasma treatment, thereby improving the drainage of moisture in the fuel cell separator. ing.

  Further, for example, Patent Document 2 discloses a fuel cell separator in which a hydrophilic group is formed by immersing the fuel cell separator in an alkaline aqueous solution to improve the drainage of moisture in the fuel cell separator. Has been proposed.

  Further, for example, Patent Document 3 discloses a fuel in which the drainage of moisture in the fuel cell separator is improved by using a fuel cell separator obtained by pressure-molding conductive carbon subjected to hydrophilic treatment and a binder resin. Battery separators have been proposed.

  Further, it is not intended to improve the drainage of the fuel cell separator by subjecting the fuel cell separator to a hydrophilic treatment. For example, Patent Document 4 discloses that water or pH in which the fuel cell separator is maintained at 80 ° C. or higher. A method for removing (eluting) impurities in a fuel cell separator by immersing in an aqueous solution of −0.3 or more for 10 hours or more has been proposed.

JP 2004-103271 A JP-A-2005-71699 JP 2001-283873 A Japanese Patent Laid-Open No. 2005-5095

  However, in the fuel cell separator of Patent Document 1, since only hydrophilic treatment by plasma treatment is performed, it is difficult to form a hydrophilic group in the entire fuel cell separator, and the drainage of the fuel cell separator is sufficient. Can not be secured.

  Further, in the fuel cell separator of Patent Document 2, the hydrophilic treatment with the alkaline aqueous solution is inferior in the ability to hydrophilically treat the fuel cell separator as compared with the hydrophilic treatment by the plasma treatment, so that no hydrophilic group is formed in the entire fuel cell separator. The drainage of the fuel cell separator cannot be sufficiently ensured.

  Further, in the fuel cell separator of Patent Document 3, only conductive carbon is subjected to a hydrophilic treatment, and the binder resin is not subjected to a hydrophilic treatment. Therefore, a hydrophilic group is not formed in the binder resin, and the drainage of the fuel cell separator. Cannot be secured sufficiently.

  Further, in the method of removing impurities of Patent Document 4, since the hydrophilic treatment is not performed in the first place, the drainage of the fuel cell separator cannot be sufficiently ensured.

  The present invention is a fuel cell separator having high drainage, a method for manufacturing the fuel cell separator, a manufacturing apparatus for the fuel cell separator, and a fuel cell including the fuel cell separator.

In the method for manufacturing a fuel cell separator according to the present invention, after the fuel cell separator is subjected to a hydrophilic treatment, the fuel cell separator is immersed in an oxidant to oxidize the fuel cell separator. .

In the method for producing a separator for a fuel cell, wherein the oxidizing agent preferably contains at least one kind of hydrogen peroxide water, and warm water.

  According to the present invention, a fuel cell separator that is highly drained by oxidizing a hydrophilically treated fuel cell separator, a method for producing the fuel cell separator, a device for producing the fuel cell separator, and the fuel A fuel cell including a battery separator can be provided.

  Embodiments of the present invention will be described below.

  First, a fuel cell separator and a method for manufacturing the fuel cell separator will be described.

<Separator for fuel cell>
FIG. 1 is a schematic perspective view showing an example of the configuration of a fuel cell separator according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell separator 1 includes a separator body 10 and a reaction gas channel 12.

  The reaction gas channel 12 is for supplying a reaction gas to the electrode of the fuel cell and is a cavity. When the fuel cell separator 1 is used on the anode electrode side of the fuel cell, the reaction gas channel 12 serves as an anode gas channel for supplying an anode gas (for example, hydrogen gas). On the other hand, when used on the cathode electrode side, the reaction gas channel 12 is a cathode gas channel for supplying a cathode gas (for example, oxygen gas).

  The separator body 10 is obtained by kneading a conductive material, a binder resin, and the like, adjusting the kneaded material, molding the kneaded material with a mold or the like, hydrolyzing the molded body, and then oxidizing the molded body.

  As described above, the fuel cell separator 1 of the present embodiment obtained by oxidizing the molded article after the hydrophilic treatment has a COOH group, OH from the hydrophilic treated molded article (hydrophilic treated fuel cell separator). The amount of hydrophilic groups such as groups is large. As will be described in detail later, there is a portion (an unreacted portion) where the hydrophilic group cannot be formed only by the hydrophilic treatment, so that the hydrophilic group is formed on the entire separator body 10 by oxidizing after the hydrophilic treatment. Can do. Here, the whole means the entire surface of the oxidized portion of the separator body 10.

  Moreover, the water contact angle dispersion | variation of the separator 1 for fuel cells of this embodiment obtained by oxidizing the molded object after a hydrophilic process is 15 degrees or less. Moreover, it is preferable that the average water contact angle of the separator 1 for fuel cells of this embodiment is 55 degrees or less. As described above, by oxidizing the molded body after the hydrophilic treatment, hydrophilic groups can be formed in the entire separator body 10, so that the average water contact angle is reduced from the hydrophilic treated molded body, Variation in water contact angle can be suppressed. The average water contact angle is an average value of 10 water contact angles measured on the same surface of the separator body 10 (for example, the surface on which the reaction gas channel 12 is formed). The water contact angle variation is the difference between the maximum value and the minimum value among the 10 measured water contact angles. The water contact angle can be measured with a FAMAS dropmaster 700 manufactured by Kyowa Interface Science Co., Ltd.

  The conductive material constituting the fuel cell separator 1 according to the present embodiment is not particularly limited as long as it has electronic conductivity. For example, graphite such as natural graphite and artificial graphite, acetylene black And carbon black such as ketjen black, carbon filler such as carbon nanotube, and metal filler such as aluminum and nickel.

  The binder resin constituting the fuel cell separator 1 according to the present embodiment is not particularly limited. For example, thermoplastics such as polyethylene, polystyrene, polypropylene, polyethylene terephthalate, polycarbonate, polyamide, polyimide, and polyvinyl alcohol. Examples thereof include thermosetting resins such as resins, urea resins, melamine resins, bisphenol type epoxy resins, and novolak type epoxy resins. When a thermosetting resin is used, a curing agent (curing catalyst) such as polyamine, polyamide, imidazole derivative, Lewis acid salt, acid anhydride, or phenol resin may be used.

  As described above, the hydrophilic body is formed on the entire separator body by oxidizing the molded body after the hydrophilic treatment. For this reason, the fuel cell separator according to the present embodiment has a larger amount of hydrophilic groups, a lower average water contact angle, and a reduced water contact angle variation than the molded article subjected to the hydrophilic treatment. Therefore, the fuel cell separator according to the present embodiment is a fuel cell separator having higher drainage than the conventional hydrophilic-treated fuel cell separator (hydroformed compact).

<Manufacturing method of fuel cell separator>
In the method for manufacturing the fuel cell separator 1 according to the present embodiment, the formed article subjected to hydrophilic treatment (hydrophilic separator for fuel cell) is oxidized using an oxidizing agent.

  The hydrophilic treatment is to form a hydrophilic group such as COOH group and OH group in the binder resin constituting the molded body (before the hydrophilic treatment). For example, plasma treatment, ultraviolet treatment (UV treatment), fluorine gas Processing and the like. The mechanism for forming a hydrophilic group in the binder resin is to dissociate the bonds between the binder resin molecules by plasma, ultraviolet light or other gas, or a gas such as fluorine gas, and the bond dissociated part is moisture in the air, oxygen, etc. Is oxidized to form a hydrophilic group (COOH group, OH group).

  As hydrophilic treatment such as plasma treatment, ultraviolet treatment (UV treatment), fluorine gas treatment, etc., known methods can be applied, and the treatment conditions are not particularly limited.

  The oxidation treatment is a portion where the binder resin bond-dissociated by the hydrophilic treatment using an oxidizing agent was not oxidized by moisture, oxygen, etc. in the air, that is, a portion where a hydrophilic group could not be formed ( Unreacted part) is oxidized to form a hydrophilic group.

  Examples of the oxidizing agent include ozone gas, hydrogen peroxide water, and water. Among the oxidizing agents, preferably, at least one of ozone gas, hydrogen peroxide water, and water is included. Further, ozone gas is preferable in terms of efficiently oxidizing the unreacted portion, and water is preferable in terms of cost and workability.

  Oxidation treatment that oxidizes the unreacted part using ozone gas as an oxidant, ozone gas treatment, oxidation treatment that oxidizes the unreacted part using hydrogen peroxide water, hydrogen peroxide treatment, and the unreacted part using water The oxidation treatment that oxidizes is called water treatment and will be described below.

  FIG. 2 is a diagram showing an oxidation model of the binder resin, taking as an example the case where the hydrophilic treatment is a fluorine gas treatment and the oxidation treatment is a water treatment. As shown in FIG. 2, normally, a hydrophilic group such as a COOH group is formed in the binder resin constituting the molded body (before the hydrophilic treatment) by the fluorine gas treatment. However, it is difficult to form hydrophilic groups in the binder resin of the entire molded body (before the hydrophilic treatment) only by the fluorine gas treatment, and a part of the binder resin of the molded body subjected to the hydrophilic treatment has a dotted frame in FIG. As shown by a, there is an unreacted portion. The unreacted portion has water repellency by including a C—F group. The unreacted portion is oxidized by water treatment to form a hydrophilic group such as a COOH group (fluorine in the unreacted portion is desorbed as, for example, hydrogen fluoride). As described above, by performing the oxidation treatment, a hydrophilic group can be formed in an unreacted portion of the binder resin.

  Similarly, an unreacted portion of the binder resin after the plasma treatment and ozone gas treatment can be oxidized to form a hydrophilic group.

  Water treatment is to oxidize the unreacted portion by immersing the fuel cell separator after hydrophilic treatment in water, but is not limited to this, and water is supplied to the fuel cell separator. May oxidize the unreacted part. The water used for the water treatment is preferably warm water of, for example, 40 ° C. or higher, 50 ° C. or higher, 60 ° C. or higher, or 70 ° C. or higher in terms of promoting oxidation of the unreacted portion. Hot water at 100 ° C. or higher can be used as long as the pressure is under atmospheric pressure or higher. When a special apparatus such as a pressure kettle is not used, warm water of 40 ° C to 100 ° C, 50 ° C to 100 ° C, 60 ° C to 100 ° C, or 70 ° C to 100 ° C is preferable. Furthermore, the water (warm water) is preferably pure water having a conductivity of 5 μS / cm or less in terms of promoting oxidation of the unreacted portion.

  Moreover, the immersion time of the separator for fuel cells after the hydrophilic treatment varies depending on the temperature of water and is not particularly limited. For example, the immersion time is 60 minutes to 500 minutes. FIG. 3 is a diagram showing an example of the relationship between the immersion time in which the fuel cell separator after the fluorine gas treatment is immersed in water and the concentration of eluted components in water. As immersion conditions, the fuel cell separator after the fluorine gas treatment is immersed in 100 ml of pure water at 80 ° C. The elution component concentration shown in FIG. 3 is the amount of F ions eluted from the separator for a combustion battery after performing thermal hydroxylation for each time. As shown in FIG. 3, as the immersion time elapses, the amount of elution components (fluorine ions, etc.) eluted from the fuel cell separator after the fluorine gas treatment increases, and almost no elution occurs after a certain period of time. Moreover, even if it immerses in 100 ml of pure water again at 80 degreeC, an elution component is hardly detected. That is, the immersion by water treatment may be at least once. Moreover, as shown in FIG. 3, since the time until the maximum concentration of the eluted component at the first immersion is reached is slow, the oxidation of the unreacted portion of the binder resin by water treatment is considered to be a hydrolysis reaction. .

Generally, a cyanoacrylate adhesive or the like is used for adhesion between the fuel cell separator and the adjacent member (sealing plate, electrolyte membrane, other fuel cell separator, etc.). A cyanoacrylate adhesive or the like is anionic polymerization, and a base such as —OH (water in the air), CH ₃ OH, NaOH, or amine is used as a reaction initiator to cause a crosslinking reaction (curing). On the fuel cell separator, hydrophilic groups such as COOH groups are formed by the above water treatment. In addition, hydrofluoric acid, formic acid, acetic acid, and the like may be generated as by-products. When the above by-products remain on the fuel cell separator, the surface of the fuel cell separator shows acidity, neutralizes the base that is the reaction initiator, and poor adhesion between adjacent members such as a sealing plate May occur. In the present embodiment, hydrofluoric acid, formic acid, acetic acid and the like on the fuel cell separator are removed by setting the water treatment temperature and immersion time to 60 ° C. or more and 15 minutes or more, preferably 60 ° C. or more and 360 minutes or more. It becomes possible. Therefore, even when a cyanoacrylate adhesive is used when adhering to an adjacent member such as a sealing plate, neutralization of the base that is a reaction initiator is suppressed, and the adhesion to an adjacent member such as a sealing plate is improved. be able to.

  In the ozone gas treatment, ozone gas is supplied to the fuel cell separator after the hydrophilic treatment to oxidize the unreacted portion.

  In the hydrogen peroxide treatment, the unreacted portion is oxidized by immersing the separator for a fuel cell after the hydrophilic treatment in a hydrogen peroxide solution, but is not limited thereto. For example, the unreacted portion may be oxidized by supplying hydrogen peroxide gas (or hydrogen peroxide solution) to the fuel cell separator after the hydrophilic treatment.

  In the method for manufacturing a separator for a fuel cell according to the present embodiment, the hydrophilically treated molded body (hydrophilicly treated fuel cell separator) is subjected to an oxidation treatment using an oxidant, whereby the hydrophilic processed compact as a whole. A separator for a fuel cell in which a hydrophilic group is formed can be produced. Therefore, the fuel cell separator manufactured by the manufacturing method according to the present embodiment has a larger amount of hydrophilic groups, a lower average water contact angle, and a reduced water contact angle variation than the hydrotreated molded article. is there.

  Next, the fuel cell separator manufacturing apparatus according to this embodiment will be described below.

  The fuel cell separator manufacturing apparatus according to the present embodiment includes an oxidation treatment unit that oxidizes a hydrophilic-treated molded body (hydrophilic-treated fuel cell separator).

  Further, the fuel cell separator manufacturing apparatus according to the present embodiment includes, in addition to the oxidation treatment means, a removal means for removing an elution component eluted from the fuel cell separator subjected to a hydrophilic treatment by the oxidation treatment, and a hydrophilically treated fuel. At least one of heating means for heating an oxidant for oxidizing the battery separator and detection means for detecting an elution state of an elution component eluted from the fuel cell separator hydrotreated by the oxidation treatment preferable.

  The fuel cell separator manufacturing apparatus according to this embodiment includes, as an example, an apparatus having the oxidation treatment means, and also includes the removal means, the heating means, and the detection means in addition to the oxidation treatment means. Will be described below as another example.

  FIG. 4 is a schematic cross-sectional view showing an example of the configuration of the fuel cell separator manufacturing apparatus according to the present embodiment. As shown in FIG. 4, the fuel cell separator manufacturing apparatus 2 includes an oxidation treatment tank 14 as an oxidation treatment means for oxidizing a hydrophilically treated fuel cell separator 20, and a hydrophilically treated fuel cell separator 20. Is provided with a fuel cell separator holding jig 16 and an exhaust duct 18 for exhausting volatile components of the oxidant 22 accommodated in the oxidation treatment tank 14.

  The oxidation treatment tank 14 is made of a material such as a metal, glass, resin, or the like, which is less corrosive to components (e.g., hydrogen fluoride) eluted from the fuel cell separator 20 that has been hydrophilically treated by the oxidant 22 and the oxidation treatment. There is no particular limitation as long as it is configured.

  As shown in FIG. 4, the oxidation treatment tank 14 includes a fuel cell separator holding jig 16, a hydrophilic treated fuel cell separator 20, and an oxidation treatment for oxidizing the hydrophilic treated fuel cell separator. The agent 22 can be accommodated.

  In the fuel cell separator manufacturing apparatus 2, first, the fuel cell separator holding jig 16 holding the fuel cell separator 20 subjected to the hydrophilic treatment is put into the oxidation treatment tank 14. Next, the oxidizing agent 22 is put into the oxidation treatment tank 14 and the fuel cell separator 20 subjected to the hydrophilic treatment is oxidized. The order in which the fuel cell separator holding jig 16 and the oxidant 22 are charged is not particularly limited. The oxidizing agent 22 and the oxidation treatment are as described above.

  FIG. 5 is a schematic cross-sectional view showing another configuration example of the fuel cell separator manufacturing apparatus according to the present embodiment. As shown in FIG. 5, the fuel cell separator manufacturing apparatus 3 includes an oxidation treatment tank 14 and an ion exchange resin as a removing means for removing the eluted components eluted from the fuel cell separator 20 that has been hydrophilically treated by the oxidation treatment. A column 24, a circulation unit 26, a heater 28 as a heating means for heating the oxidant 22 for oxidizing the hydrophilically treated fuel cell separator 20, a temperature measuring unit 30, and a fuel cell by oxidation treatment An ion meter 32 and a pH meter 34 are provided as detection means for detecting the elution state of the eluted components eluted from the separator. Further, the same components as those of the fuel cell separator manufacturing apparatus shown in FIG.

  The circulation unit 26 includes a circulation pump 36, supply pipes 38a and 38b, and a discharge pipe 40. In the circulation unit 26, the discharge pipe 40 connects the oxidation treatment tank 14 outlet (not shown) and the ion exchange resin column 24 inlet (not shown), and the supply pipe 38a is the ion exchange resin column 24 outlet (not shown). And the suction side (not shown) of the circulation pump 36, and the supply pipe 38b connects the discharge side (not shown) of the circulation pump 36 and the inlet of the oxidation treatment tank 14 (not shown).

  The temperature measurement unit 30 includes a thermocouple 42 and a temperature measurement device 44. The temperature measurement unit 30 can measure the temperature of the oxidant.

  The fuel cell separator manufacturing apparatus 3 performs the oxidation treatment in the same manner as the fuel cell separator manufacturing apparatus 2 described above, and at this time, the circulation pump 36 is operated. After the circulation pump 36 is operated, the oxidant 22 in the oxidation treatment tank 14 passes through the discharge pipe 40 from the oxidation treatment tank 14 outlet and is supplied to the ion exchange resin column 24 from the ion exchange resin column 24 inlet. Passes through (transmits). As the oxidant 22 permeates through the ion exchange resin column 24, the elution component contained in the oxidant 22 (eluted from the fuel cell separator 20 that has been subjected to hydrophilic treatment by oxidation treatment) is removed. The oxidant 22 from which the eluted components have been removed passes through the supply pipe 38a from the outlet of the ion exchange resin column 24, is supplied to the suction side of the circulation pump 36, and passes from the discharge side of the circulation pump 36 through the supply pipe 38b to the oxidation treatment tank 14. It is supplied to the oxidation treatment tank 14 from the inlet.

  As described above, by providing the ion exchange resin column 24, the elution component contained in the oxidant 22 can be removed, so that the oxidant 22 with high purity can be supplied to the oxidation treatment tank 14. Therefore, the unreacted portion of the fuel cell separator 20 subjected to the hydrophilic treatment can be efficiently oxidized, and the immersion time of the fuel cell separator 20 subjected to the hydrophilic treatment in the oxidizing agent 22 can be shortened.

  In addition, the heater 28 shown in FIG. 5 can heat the oxidant 22 by supplying electric power to the heater 28 when performing the oxidation treatment. As a result, the temperature of the oxidizing agent 22 is maintained at a temperature suitable for the oxidation treatment, so that the unreacted portion of the fuel cell separator 20 subjected to the hydrophilic treatment can be efficiently oxidized.

  Further, the ion meter 32 and the pH meter 34 shown in FIG. 5 can detect the elution state of the elution component eluted from the hydrophilic-treated fuel cell separator 20. Further, the ion meter 32 and the pH meter 34 are not necessarily required, and at least one of them may be used.

  FIG. 6 is a schematic cross-sectional view showing another configuration example of the fuel cell separator manufacturing apparatus according to the present embodiment. As shown in FIG. 6, the fuel cell separator manufacturing apparatus 4 includes a filter as an impurity removing means for removing impurities peeled from the fuel cell separator that has been hydrophilically treated by oxidation treatment in the discharge pipe 40 (40a, 40b). 46 is provided. Other configurations of the fuel cell separator manufacturing apparatus are the same as those of the fuel cell separator manufacturing apparatus 3 shown in FIG.

  By providing the filter 46, impurities contained in the oxidant 22 that passes through the discharge pipe 40 a can be removed, so that the oxidant 22 having a high purity can be supplied to the oxidation treatment tank 14. Here, the impurity refers to a metal or the like attached to the fuel cell separator 20 that has been subjected to a hydrophilic treatment.

  FIG. 7 is a schematic cross-sectional view showing another configuration example of the fuel cell separator manufacturing apparatus according to the present embodiment. As shown in FIG. 7, the fuel cell separator manufacturing apparatus 5 includes pipe switching valves 48a and 48b provided in the discharge pipe 40b and the supply pipe 38a, and a connection pipe 50 that connects the discharge pipe 40b and the supply pipe 38a. It is to be prepared. Other configurations of the fuel cell separator manufacturing apparatus are the same as those of the fuel cell separator 4 manufacturing apparatus shown in FIG.

  Supplying the oxidant 22 passing through the discharge pipe 40b to the ion exchange resin column 24 (arrow b in FIG. 7) or the connection pipe 50 (arrow c in FIG. 7) by opening and closing the pipe switching valve 48a. Alternatively, the fuel cell separator can be discharged out of the system 5 (arrow d1 in FIG. 7). On the other hand, by opening and closing the pipe switching valve 48b, the oxidant 22 is discharged out of the system of the fuel cell separator manufacturing apparatus 5 (arrow d2 in FIG. 7) or supplied to the circulation pump 36 (arrow in FIG. 7). e) etc. Therefore, since the oxidizing agent 22 can be supplied to the oxidation treatment tank 14 without being supplied to the ion exchange resin column 24, the life of the ion exchange resin column 24 can be extended.

  As described above, the fuel cell separator manufacturing apparatus according to the present embodiment (fuel cell separator manufacturing apparatus 2 shown in FIG. 4) includes an oxidation treatment means for oxidizing the hydrophilically treated fuel cell separator, The unreacted portion of the fuel cell separator that has been subjected to hydrophilic treatment can be oxidized. Furthermore, the fuel cell separator manufacturing apparatus according to the present embodiment (for example, the fuel cell separator manufacturing apparatus 3 shown in FIG. 5) is a fuel cell separator that has been subjected to a hydrophilic treatment by oxidation treatment in addition to the oxidation treatment means. Removing means for removing the eluted components eluted from the fuel, heating means for heating the oxidizing agent for the fuel cell separator subjected to hydrophilic treatment, elution of the eluted components eluted from the fuel cell separator hydrophilically treated by the oxidation treatment By providing at least one of detection means for detecting the elution state, the unreacted portion of the fuel cell separator that has been subjected to hydrophilic treatment can be efficiently oxidized.

  Next, a fuel cell including the fuel cell separator according to the present embodiment will be described.

  FIG. 8 is a schematic cross-sectional view showing an example of the configuration of the fuel cell according to the present embodiment. As shown in FIG. 8, the fuel cell 6 includes an electrolyte membrane 52, an anode electrode 58 including an anode electrode catalyst layer 54 and an anode electrode diffusion layer 56, and a cathode electrode including a cathode electrode catalyst layer 60 and a cathode electrode diffusion layer 62. 64, an anode electrode fuel cell separator 66, and a cathode electrode fuel cell separator 68. Here, the anode electrode fuel cell separator 66 and the cathode electrode fuel cell separator 68 are the fuel cell separator 1 described above.

  As shown in FIG. 8, in the fuel cell 6 according to this embodiment, the anode electrode 58 is opposed to one surface of the electrolyte membrane 52, and the cathode electrode 64 is opposed to the other surface with the electrolyte membrane 52 interposed therebetween. And the anode electrode side fuel cell separator 66 and the cathode electrode side fuel cell separator 68 that sandwich both outer sides of the membrane electrode assembly 74. The hollow portions of the anode electrode side fuel cell separator 66 and the cathode electrode side fuel cell separator 68 are an anode gas supply channel 70 for supplying anode gas and cathode gas to the anode electrode 58 and cathode electrode 64, and a cathode gas supply channel. 72.

  The electrolyte membrane 52 used in the present embodiment is not particularly limited as long as it does not have electron transfer properties but has proton conductivity. For example, a perfluorosulfonic acid resin film, a copolymer film of a trifluorostyrene derivative, a polybenzimidazole film impregnated with phosphoric acid, an aromatic polyether ketone sulfonic acid film, and the like can be given. Specific examples include Nafion (registered trademark).

  The anode electrode side catalyst layer 54 and the cathode electrode side catalyst layer 60 are, for example, a mixture of carbon carrying a metal catalyst such as platinum or ruthenium and a perfluorosulfonic acid based electrolyte or the like to mix the anode electrode side diffusion layer 56 and the cathode. It is formed on the pole side diffusion layer 62 or the electrolyte membrane 52. Examples of the carbon include carbon black such as acetylene black, furnace black, channel black, and thermal black.

  The anode electrode diffusion layer 56 and the cathode electrode diffusion layer 62 are not particularly limited as long as the materials have high conductivity and high reaction gas diffusibility, but are preferably porous conductor materials. Examples thereof include porous carbon materials such as carbon cloth and carbon paper.

  As described above, the fuel cell according to the present embodiment manufactured as described above includes the oxidized fuel cell separator, so that, for example, even when the amount of water generated from the cathode electrode side increases, Since it can suppress staying in the separator for fuel cells, the power generation performance of a fuel cell can be maintained.

  The fuel cell according to the present embodiment can be used as, for example, a small power source for mobile devices such as a mobile phone and a portable personal computer, a power source for automobiles, and a household power source.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely, the present invention is not limited to the following examples.

<Examples 1-9>
The fuel cell separator treated with fluorine gas was immersed in warm water (oxidant 22) at 70 ° C. in an oxidation treatment tank 14 as shown in FIG. In Example 2, a fuel cell separator treated with fluorine gas was immersed in warm water at 70 ° C. in an oxidation treatment tank for 240 minutes, and then immersed in warm water at 70 ° C. in another oxidation treatment tank for 240 minutes. is there. In Example 3, a separator for a fuel cell treated with fluorine gas was immersed in warm water at 70 ° C. in an oxidation treatment tank for 240 minutes, immersed in warm water at 70 ° C. in another oxidation treatment tank for 240 minutes, and further oxidized. It is immersed in warm water of 70 ° C. in a treatment tank for 240 minutes. Examples 4 and 7 are the same as Example 1 except that the immersion time was set to 360 minutes and 480 minutes, respectively. Examples 5 and 8 were the same as Example 2 except that the immersion time was 360 minutes and 480 minutes, respectively. Further, Examples 6 and 9 are the same as Example 3 except that the immersion time was set to 360 minutes and 480 minutes, respectively.

<Comparative Examples 1-3>
Comparative Examples 1 to 3 are fuel cell separators treated with fluorine gas, and no hydrophilic treatment was performed.

<Amount of hydrophilic group in Examples 1 to 9 and Comparative Examples 1 to 3>
When the amount of hydrophilic groups in Examples 1 to 9 that were oxidized and Comparative Examples 1 to 3 that were not oxidized was measured, the amount of hydrophilic groups was increased in Examples 1 to 9 that were oxidized.

<Water contact angle measurement of Examples 1-9 and Comparative Examples 1-3>
FIG. 9 is a schematic diagram of the fuel cell separators of Examples 1 to 9 and Comparative Examples 1 to 3 as seen from the direction of the arrow z in FIG. Five points each of water near the reaction gas inlet side of the fuel cell separator (for example, the dotted frame x shown in FIG. 9) and near the reaction gas outlet side of the fuel cell separator (for example, the dotted frame y shown in FIG. 9). The contact angle was measured. The water contact angle was measured using a FAMAS dropmaster 700 manufactured by Kyowa Kagaku. The measurement conditions are summarized in Table 1.

  FIG. 10 is a diagram illustrating water contact angles of Examples 1 to 9 and Comparative Examples 1 to 3. FIG. 11 is a diagram showing the state of water droplets dropped on Example 4 and Comparative Example 1. FIG. As shown in FIG. 10, the average water contact angles (average values of 10 points of water contact angles) of Examples 1 to 9 subjected to the oxidation treatment are lower than the average water contact angles of Comparative Examples 1 to 3 that were not oxidized. The value is shown. Moreover, while the variation of the water contact angle of Comparative Examples 1 to 3 (difference between the maximum value and the minimum value of the water contact angle) was 25 ° or more, the variation of the water contact angle of Examples 1 to 9 was It could be suppressed to 15 ° or less. FIG. 11A is a diagram showing the state of water droplets dropped on Comparative Example 1, and FIG. 11B is a diagram showing the state of water droplets dropped on Example 4. The water droplets 76 on Comparative Example 1 and Example 4 shown in FIG. 11 were dropped from the tip 78 of the dropper into the region where the water contact angle was measured, and were observed with an optical microscope. As shown in FIG. 11 (a), the water droplets 76 dropped on the comparative example 1 are in a non-uniform state (a state showing wettability and a state showing water repellency), whereas the water droplets dropped on the example 4 76 was a substantially uniform state (state showing wettability). Among Examples 1 to 9, Examples 7 to 9 immersed in warm water at 70 ° C. for 480 minutes showed good results in both average water contact angle and variation.

<Evaluation of elution amount of hydrofluoric acid (fluorine ion)>
A fuel cell separator test piece treated with fluorine gas (Example 10: length 40 mm × width 20 mm × thickness 25 mm) was immersed in hot water of 60 ° C. in an oxidation treatment tank 14 as shown in FIG. The concentration of fluorine ions in warm water at 5 minutes, 15 minutes, and 30 minutes was measured by an ion chromatograph (IC-2001, manufactured by Tosoh Corporation). The result is shown in FIG. FIG. 12 is a diagram showing the relationship between the immersion time and the elution amount of fluorine ions.

  Fluorine gas-treated fuel cell separator test pieces (Example 11: length 40 mm × width 20 mm × thickness 25 mm) were respectively placed in hot water at 60 ° C., 70 ° C., and 80 ° C. in an oxidation treatment tank 14 as shown in FIG. It was immersed for 15 minutes. The concentration of fluorine ions in warm water at each temperature was measured by ion chromatography. The result is shown in FIG. FIG. 13 is a diagram showing the relationship between the immersion temperature and the elution amount of fluorine ions.

  A fuel cell separator test piece treated with fluorine gas (Example 12: length 40 mm × width 25 mm × thickness 20 mm) was immersed in warm water at 60 ° C. in an oxidation treatment tank 14 as shown in FIG. The fluorine ion concentration in warm water at 30 minutes, 60 minutes, 90 minutes, 120 minutes, 240 minutes, 360 minutes, and 480 minutes was measured by ion chromatography. Further, after immersion, the test piece was further immersed in warm water at 60 ° C. for 240 minutes, 360 minutes, and 480 minutes (boiling test), and the fluorine ion concentration in the warm water was measured by ion chromatography. The result is shown in FIG. FIG. 14 is a diagram showing the relationship between the immersion time and the elution amount of fluorine ions.

  As shown in FIG. 12, as the immersion time increases, the elution concentration of fluorine ions from the fuel cell separator test piece also increases. Moreover, as shown in FIG. 13, the elution density | concentration of a fluorine ion from a fuel cell separator test piece also increases with the increase in immersion temperature. Therefore, the oxidation treatment can be promoted by increasing the immersion time and the immersion temperature. Moreover, as shown in FIG. 14, the elution amount of fluorine ions is saturated by performing water treatment (oxidation treatment) under conditions of an immersion temperature of 60 ° C. and an immersion time of 360 minutes or more. Therefore, by performing water treatment (oxidation treatment) under conditions of an immersion temperature of 60 ° C. and an immersion time of 360 minutes or more, hydrophilic groups can be formed in most unreacted portions of the fuel cell separator. Moreover, since it can suppress that the separator surface for fuel cells becomes extremely acidic by this, adhesiveness with adjacent members, such as a sealing plate, can be improved.

<Examples 13 to 27>
A fuel cell separator treated with fluorine gas was immersed (oxidized) in warm water at 60 ° C. for 240 minutes in an oxidation treatment tank 14 shown in FIG. The immersion temperature and immersion time of Example 13 were set to 1 cycle, and the results of 2 cycles were used as Example 14 and 3 cycles were taken as Example 15. A fuel cell separator treated with fluorine gas was immersed (oxidized) in warm water at 60 ° C. in the oxidation treatment tank 14 shown in FIG. The immersion temperature and immersion time of Example 16 were set to 1 cycle, the results of 2 cycles performed in Example 17, the results of 3 cycles performed in Example 18, the results of 4 cycles performed in Example 19, and those in 5 cycles performed Example 20 was carried out for 6 cycles and was designated as Example 21. A fuel cell separator treated with fluorine gas was immersed (oxidized) in warm water at 60 ° C. in an oxidation treatment tank 14 shown in FIG. The immersion temperature and immersion time of Example 22 were taken as 1 cycle, and the results of 2 cycles were taken as Example 23 and the results of 3 cycles were taken as Example 24. A fuel cell separator treated with fluorine gas was immersed (oxidized) in warm water at 60 ° C. in an oxidation treatment tank 14 shown in FIG. The immersion temperature and immersion time of Example 25 were set to 1 cycle, and the results of 2 cycles were taken as Example 26 and the results of 3 cycles were taken as Example 27. In Examples 13 to 24, the surface was washed with running water after the oxidation treatment, and in Examples 25 to 27, the surface after the oxidation treatment was not washed.

  FIG. 15 is a diagram showing water contact angles of Examples 13 to 27. The water contact angle was measured by the same method as described above. As shown in FIG. 15, the dispersion | variation in the water contact of Examples 13-27 was 15 degrees or less, and the average value of the water contact angle was 60 degrees or less. In particular, in Examples 16 to 27 (immersion temperature 60 ° C., immersion time 360 minutes or more), the water contact angle variation was 12 ° or less, and the average value of the water contact angle could be suppressed to 48 ° or less.

  In this way, by oxidizing the fuel cell separator after the hydrophilic treatment, the amount of hydrophilic groups is increased and the water contact angle is reduced compared to the fuel cell separator that has not been subjected to the oxidation treatment. It was possible to suppress the variation of. Therefore, it is possible to suppress water generated during power generation of the fuel cell from staying in the fuel cell separator, and to suitably drain the fuel cell system.

It is a model perspective view which shows an example of a structure of the separator for fuel cells which concerns on embodiment of this invention. It is a figure which shows the oxidation model of binder resin for the case where the hydrophilic treatment is fluorine gas treatment and the oxidation treatment is water treatment. It is a figure which shows an example of the relationship between the immersion time which immersed the separator for fuel cells after a fluorine gas process in water, and the elution component density | concentration in water. It is a schematic cross section which shows an example of a structure of the manufacturing apparatus of the separator for fuel cells which concerns on this embodiment. It is a schematic cross section which shows the other structural example of the manufacturing apparatus of the separator for fuel cells which concerns on this embodiment. It is a schematic cross section which shows the other structural example of the manufacturing apparatus of the separator for fuel cells which concerns on this embodiment. It is a schematic cross section which shows the other structural example of the manufacturing apparatus of the separator for fuel cells which concerns on this embodiment. It is a schematic cross section which shows an example of a structure of the fuel cell which concerns on this embodiment. It is the schematic diagram of the separator for fuel cells of Examples 1-9 and Comparative Examples 1-3 seen from the arrow z direction of FIG. It is a figure which shows the water contact angle of Examples 1-9 and Comparative Examples 1-3. It is a figure which shows the state of the water drop dripped at Example 4 and Comparative Example 1. FIG. It is a figure which shows the relationship between immersion time and the elution amount of a fluorine ion. It is a figure which shows the relationship between immersion temperature and the elution amount of a fluorine ion. It is a figure which shows the relationship between immersion time and the elution amount of a fluorine ion. It is a figure which shows the water contact angle of Examples 13-27.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell separator, 2, 3, 4, 5 Manufacturing apparatus of fuel cell separator, 6 Fuel cell, 10 Separator main body, 12 Reaction gas flow path, 14 Oxidation treatment tank, 16 Fuel cell separator holding jig, 18 Exhaust duct, 20 Hydrophilic separator for fuel cell, 22 Oxidant, 24 Ion exchange resin column, 26 Circulation unit, 28 Superheater, 30 Temperature measurement unit, 32 Ion meter, 34 pH meter, 36 Circulation pump, 38a , 38b Supply pipe, 40, 40a, 40b Discharge pipe, 42 Thermocouple, 44 Temperature measuring device, 46 Filter, 48a, 48b Pipe switching valve, 50 Connection pipe, 52 Electrolyte membrane, 54 Anode electrode catalyst layer, 56 Anode electrode diffusion Layer, 58 anode electrode, 60 cathode electrode catalyst layer, 62 parts Cathode electrode diffusion layer, 64 cathode electrode, 66 anode electrode fuel cell separator, 68 cathode electrode fuel cell separator, 70 anode gas channel, 72 cathode gas channel, 74 membrane-electrode assembly, 76 water drop, 78 dropper tip.

Claims (2)

A method for producing a fuel cell separator, comprising: subjecting a fuel cell separator to a hydrophilic treatment; and immersing the fuel cell separator subjected to the hydrophilic treatment in an oxidizing agent to oxidize the fuel cell separator. . A method of manufacturing a fuel cell separator according to claim 1, wherein the oxidizing agent is hydrogen peroxide water, and a manufacturing method of a fuel cell separator characterized in that it comprises at least one kind of hot water.