JP5733182B2 - Manufacturing method of membrane electrode assembly - Google Patents

Manufacturing method of membrane electrode assembly Download PDF

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JP5733182B2
JP5733182B2 JP2011264266A JP2011264266A JP5733182B2 JP 5733182 B2 JP5733182 B2 JP 5733182B2 JP 2011264266 A JP2011264266 A JP 2011264266A JP 2011264266 A JP2011264266 A JP 2011264266A JP 5733182 B2 JP5733182 B2 JP 5733182B2
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catalyst layer
electrolyte
electrolyte membrane
electrode assembly
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敬祐 藤田
敬祐 藤田
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Toyota Motor Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Description

本発明は、膜電極接合体の製造方法、膜電極接合体および燃料電池に関する。   The present invention relates to a method for producing a membrane electrode assembly, a membrane electrode assembly, and a fuel cell.

燃料ガスと酸化ガスとの電気化学反応によって発電する燃料電池として、プロトン伝導性を有する電解質膜の両面に、触媒を担持した導電性の粒子と電解質樹脂とを含む触媒層を接合した膜電極接合体（以下、ＭＥＡ（Ｍｅｍｂｒａｎｅ Ｅｌｅｃｔｒｏｄｅ Ａｓｓｅｍｂｌｙ）ともいう）を備えたものが知られている。燃料電池においては、ＭＥＡの備える触媒層の強度が十分でない場合には、長時間の運転中に触媒層にクラックが発生して、発電性能が低下することがある。そこで、特許文献１に記載の技術では、熱処理により触媒層の強度を向上させている。   As a fuel cell that generates electricity by electrochemical reaction between fuel gas and oxidant gas, a membrane electrode joint in which a catalyst layer containing conductive particles carrying a catalyst and an electrolyte resin is joined to both sides of an electrolyte membrane having proton conductivity A body having a body (hereinafter also referred to as MEA (Membrane Electrode Assembly)) is known. In a fuel cell, if the strength of the catalyst layer provided in the MEA is not sufficient, cracks may occur in the catalyst layer during long-time operation, and power generation performance may be reduced. Therefore, in the technique described in Patent Document 1, the strength of the catalyst layer is improved by heat treatment.

しかしながら、特許文献１に記載の技術では、触媒層を熱処理した後に電解質膜と接合しているため、触媒層と電解質膜の界面の抵抗が上昇してプロトン伝導性が低下するおそれがあった。   However, in the technique described in Patent Document 1, since the catalyst layer is bonded to the electrolyte membrane after the heat treatment, the resistance at the interface between the catalyst layer and the electrolyte membrane is increased, and the proton conductivity may be decreased.

特開２００７−９５５８２号公報JP 2007-95582 A 特開２００５−２７６５９９号公報JP 2005-276599 A

前述の問題を考慮し、本発明が解決しようとする課題は、膜電極接合体において、触媒層の強度の向上とプロトン伝導特性の向上とを両立可能な技術を提供することである。   In view of the above-described problems, the problem to be solved by the present invention is to provide a technique capable of achieving both improvement in the strength of the catalyst layer and improvement in proton conduction characteristics in the membrane electrode assembly.

本発明は、上述の課題の少なくとも一部を解決するためになされたものであり、以下の形態又は適用例として実現することが可能である。
本発明の第１の形態は、膜電極接合体の製造方法であって、
第１の電解質樹脂を含む触媒層を、第２の電解質樹脂を含む電解質膜上に形成して膜電極接合体を作製する工程と、
水又は有機溶媒を含む雰囲気において、前記作製された膜電極接合体の前記触媒層と前記電解質膜とを、前記第１の電解質樹脂および前記第２の電解質樹脂のガラス転移点以上の温度で、前記触媒層と前記電解質膜とに、０．１ＭＰａ以上０．５ＭＰａ以下の圧力を加えて熱処理する工程と、
を備える膜電極接合体の製造方法である。 SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
A first aspect of the present invention is a method of manufacturing a membrane electrode assembly,
Forming a membrane electrode assembly by forming a catalyst layer containing a first electrolyte resin on an electrolyte membrane containing a second electrolyte resin ;
In an atmosphere containing water or an organic solvent, the fabricated membrane electrode assembly wherein the catalyst layer of said electrolyte membrane, in the first electrolyte resin and the second temperature higher than the glass transition point of the electrolyte resin, A step of heat-treating the catalyst layer and the electrolyte membrane by applying a pressure of 0.1 MPa or more and 0.5 MPa or less ;
It is a manufacturing method of a membrane electrode assembly provided with this.

［適用例１］電極接合体の製造方法であって、第１の電解質樹脂を含む触媒層と、電解質膜と、を用意する工程と、水又は有機溶媒を含む雰囲気において、前記触媒層と前記電解質膜とを前記第１の電解質樹脂のガラス転移点以上の接合温度で接合する工程と、を備える膜電極接合体の製造方法。この方法によれば、触媒層と電解質膜とをガラス転移点以上で接合するので、界面での接合強度が向上する。また、水又は有機溶媒を含む雰囲気で接合するので、熱処理による水分の揮発が抑制され、これによりプロトン伝導性が向上する。よって、膜電極接合体において、触媒層の強度の向上とプロトン伝導特性の向上との両立を図ることができる。 [Application Example 1] A method for producing an electrode assembly, comprising: preparing a catalyst layer containing a first electrolyte resin; and an electrolyte membrane; and in an atmosphere containing water or an organic solvent, Joining the electrolyte membrane at a joining temperature equal to or higher than the glass transition point of the first electrolyte resin. According to this method, since the catalyst layer and the electrolyte membrane are bonded at the glass transition point or higher, the bonding strength at the interface is improved. Moreover, since it joins in the atmosphere containing water or an organic solvent, the volatilization of the water | moisture content by heat processing is suppressed, and, thereby, proton conductivity improves. Therefore, in the membrane electrode assembly, it is possible to achieve both improvement in the strength of the catalyst layer and improvement in proton conduction characteristics.

［適用例２］適用例１記載の製造方法であって、前記電解質膜は第２の電解質樹脂を含み、前記接合温度は、前記第１の電解質樹脂および前記第２の電解質樹脂のガラス転移点以上である、製造方法。この方法によれば、触媒層と電解質膜とのその界面での絡み合いや結晶化が促進されるので、触媒層と電解質膜との接合強度を向上させることができる。 Application Example 2 In the manufacturing method according to Application Example 1, the electrolyte membrane includes a second electrolyte resin, and the bonding temperature is a glass transition point of the first electrolyte resin and the second electrolyte resin. This is the manufacturing method. According to this method, since the entanglement and crystallization at the interface between the catalyst layer and the electrolyte membrane are promoted, the bonding strength between the catalyst layer and the electrolyte membrane can be improved.

［適用例３］適用例１又は適用例２記載の製造方法であって、前記ガラス転移点は１１０度以上１４０度以下であり、前記接合温度は２００度以下である、製造方法。この方法によれば、１１０度以上１４０度以下のガラス転移点を有する電解質樹脂を備える触媒層の強度を向上させることができるとともに、電解質樹脂の分解を抑制することができる。 [Application Example 3] The manufacturing method according to Application Example 1 or Application Example 2, wherein the glass transition point is not less than 110 degrees and not more than 140 degrees, and the bonding temperature is not more than 200 degrees. According to this method, the strength of the catalyst layer including an electrolyte resin having a glass transition point of 110 degrees or more and 140 degrees or less can be improved, and decomposition of the electrolyte resin can be suppressed.

［適用例４］適用例１から適用例３までのいずれか一の適用例記載の製造方法であって、前記触媒層と前記電解質膜とを、０．１ＭＰａ以上０．５ＭＰａ以下の圧力で接合する、製造方法。この方法によれば、比較的低い圧力で触媒層と電解質膜とを接合するので、触媒層や電解質膜の変形を抑制することができる。 [Application Example 4] The manufacturing method according to any one of Application Examples 1 to 3, wherein the catalyst layer and the electrolyte membrane are joined at a pressure of 0.1 MPa to 0.5 MPa. A manufacturing method. According to this method, since the catalyst layer and the electrolyte membrane are joined at a relatively low pressure, deformation of the catalyst layer and the electrolyte membrane can be suppressed.

本発明は、上述した膜電極接合体の製造方法としての構成のほか、膜電極接合体、膜電極接合体を備える燃料電池、その燃料電池を備えた移動用車両や建物等に設置する定置型の発電装置としても構成することができる。   In addition to the above-described structure as a method for manufacturing a membrane electrode assembly, the present invention provides a membrane electrode assembly, a fuel cell including the membrane electrode assembly, a stationary vehicle installed in a mobile vehicle, a building, or the like including the fuel cell. It can also be configured as a power generator.

本発明の一実施形態としての製造方法によって製造されたＭＥＡを備える燃料電池の概略構成を示す部分断面図である。It is a fragmentary sectional view showing a schematic structure of a fuel cell provided with MEA manufactured by a manufacturing method as one embodiment of the present invention. ＭＥＡの製造方法のフローチャートである。It is a flowchart of the manufacturing method of MEA. 段階的に熱処理を行う例を説明する図である。It is a figure explaining the example which heat-processes in steps. 本実施形態による効果を説明する図である。It is a figure explaining the effect by this embodiment. セル電圧の測定結果を示す図である。It is a figure which shows the measurement result of a cell voltage.

Ａ．燃料電池の構成：
図１は、本発明の一実施形態としての製造方法によって製造されたＭＥＡ１０を備える、燃料電池１００の概略構成を示す部分断面図である。この燃料電池１００は、反応ガスとして燃料ガス（例えば水素）と酸化剤ガス（例えば酸素）の供給を受けて発電する固体高分子形燃料電池である。燃料電池１００は、複数の単セル３０が積層されたスタック構造を有する。 A. Fuel cell configuration:
FIG. 1 is a partial cross-sectional view showing a schematic configuration of a fuel cell 100 including an MEA 10 manufactured by a manufacturing method according to an embodiment of the present invention. The fuel cell 100 is a solid polymer fuel cell that generates electric power by receiving supply of a fuel gas (for example, hydrogen) and an oxidant gas (for example, oxygen) as reaction gases. The fuel cell 100 has a stack structure in which a plurality of single cells 30 are stacked.

単セル３０は、電解質膜１１と、電解質膜１１の両面にそれぞれ形成されるアノード側触媒層１２ａおよびカソード側触媒層１２ｃと、を有するＭＥＡ１０を備える。ＭＥＡ１０の一方の面にはアノード側ガス拡散層２２ａが、もう一方の面にカソード側ガス拡散層２２ｃが接合されており、アノード側ガス拡散層２２ａはアノード側セパレータ３３ａと、カソード側ガス拡散層２２ｃはカソード側セパレータ３３ｃと隣接している。アノード側ガス拡散層２２ａとアノード側セパレータ３３ａの間には、燃料ガス流路３４ａが、カソード側ガス拡散層２２ｃとカソード側セパレータ３３ｃとの間には、酸化剤ガス流路３４ｃが形成されている。   The single cell 30 includes an MEA 10 having an electrolyte membrane 11 and an anode side catalyst layer 12a and a cathode side catalyst layer 12c formed on both surfaces of the electrolyte membrane 11, respectively. An anode-side gas diffusion layer 22a is joined to one surface of the MEA 10, and a cathode-side gas diffusion layer 22c is joined to the other surface. 22c is adjacent to the cathode separator 33c. A fuel gas channel 34a is formed between the anode side gas diffusion layer 22a and the anode side separator 33a, and an oxidant gas channel 34c is formed between the cathode side gas diffusion layer 22c and the cathode side separator 33c. Yes.

電解質膜１１は、プロトン伝導性を有するポリマー（以下、電解質樹脂ともいう）の薄膜によって構成することができ、例えば、フッ素樹脂系のイオン交換膜によって構成することができる。より具体的には、電解質膜１１は、ナフィオン（Ｎａｆｉｏｎ：登録商標）などを用いることができる。   The electrolyte membrane 11 can be constituted by a thin film of a polymer having proton conductivity (hereinafter also referred to as electrolyte resin), for example, a fluorine resin ion exchange membrane. More specifically, Nafion (registered trademark) or the like can be used for the electrolyte membrane 11.

アノード側触媒層１２ａおよびカソード側触媒層１２ｃは、白金や白金合金などの触媒を担持したカーボン粒子などの導電性粒子と、電解質樹脂とを含んでおり、燃料電池１００の電極として作用する。以降、アノード側触媒層１２ａおよびカソード側触媒層１２ｃを、まとめて「触媒層１２」ともいう。   The anode-side catalyst layer 12 a and the cathode-side catalyst layer 12 c contain conductive particles such as carbon particles carrying a catalyst such as platinum or a platinum alloy and an electrolyte resin, and function as electrodes of the fuel cell 100. Hereinafter, the anode side catalyst layer 12a and the cathode side catalyst layer 12c are also collectively referred to as “catalyst layer 12”.

アノード側ガス拡散層２２ａおよびカソード側ガス拡散層２２ｃは、ガス透過性を有するとともに導電性を有する材料で形成されている。アノード側ガス拡散層２２ａおよびカソード側ガス拡散層２２ｃの材料としては、例えばカーボンペーパーやカーボンクロスなどの炭素系多孔質体や、金属メッシュ、発泡金属などの金属多孔質体を用いることができる。以降、アノード側ガス拡散層２２ａおよびカソード側ガス拡散層２２ｃを、まとめて「拡散層２２」ともいう。   The anode side gas diffusion layer 22a and the cathode side gas diffusion layer 22c are formed of a material having gas permeability and conductivity. As a material of the anode side gas diffusion layer 22a and the cathode side gas diffusion layer 22c, for example, a carbon-based porous body such as carbon paper or carbon cloth, or a metal porous body such as a metal mesh or a foam metal can be used. Hereinafter, the anode-side gas diffusion layer 22a and the cathode-side gas diffusion layer 22c are collectively referred to as “diffusion layer 22”.

アノード側セパレータ３３ａおよびカソード側セパレータ３３ｃは、ガス遮断性および電子伝導性を有する部材によって形成されている。本実施形態では、アノード側セパレータ３３ａおよびカソード側セパレータ３３ｃは、カーボンを圧縮してガス不透過とした緻密質カーボンによって形成されている。なお、アノード側セパレータ３３ａおよびカソード側セパレータ３３ｃは、緻密質カーボン等のカーボン製部材の他に、プレス成形されたステンレス鋼などの金属部材によって形成することができる。   The anode side separator 33a and the cathode side separator 33c are formed of members having gas barrier properties and electronic conductivity. In the present embodiment, the anode-side separator 33a and the cathode-side separator 33c are formed of dense carbon that has been made to be gas impermeable by compressing carbon. The anode side separator 33a and the cathode side separator 33c can be formed of a metal member such as press-formed stainless steel in addition to a carbon member such as dense carbon.

燃料ガス流路３４ａはアノード側ガス拡散層２２ａとアノード側セパレータ３３ａの間に、酸化剤ガス流路３４ｃはカソード側ガス拡散層２２ｃとカソード側セパレータ３３ｃとの間にそれぞれ形成されている。燃料ガス流路３４ａは水素（Ｈ2）ガスの流路であり、酸化剤ガス流路３４ｃは酸素（Ｏ2）ガスの流路である。 The fuel gas flow path 34a is formed between the anode side gas diffusion layer 22a and the anode side separator 33a, and the oxidant gas flow path 34c is formed between the cathode side gas diffusion layer 22c and the cathode side separator 33c. The fuel gas channel 34a is a hydrogen (H 2 ) gas channel, and the oxidant gas channel 34c is an oxygen (O 2 ) gas channel.

Ｂ．ＭＥＡの製造方法
図２は、ＭＥＡ１０の製造方法のフローチャートである。まずはじめに、ＭＥＡ１０の材料である電解質膜１１と触媒インクとを用意する（ステップＳ１０）。本実施形態では、電解質膜１１はデュポン製Ｎａｆｉｏｎ膜ＮＲ２１１を用いる。触媒インクは、白金１３をカーボン粒子によって担持した触媒担体１６と、電解質樹脂１７を含む電解質溶液（デュポン製Ｎａｆｉｏｎ溶液Ｄ２０２０）とを混合して作製する。なお、本実施形態では、電解質膜１１を形成する電解質樹脂（本願の「第２の電解質樹脂」に相当）と触媒インクに含まれる電解質樹脂（本願の「第１の電解質樹脂」に相当）は、ともにパーフルオロスルホン酸系の電解質樹脂である。 B. MEA Manufacturing Method FIG. 2 is a flowchart of a method for manufacturing the MEA 10. First, the electrolyte membrane 11 and catalyst ink which are materials of MEA10 are prepared (step S10). In this embodiment, the electrolyte membrane 11 uses a DuPont Nafion membrane NR211. The catalyst ink is prepared by mixing a catalyst carrier 16 in which platinum 13 is supported by carbon particles and an electrolyte solution (DuPont Nafion solution D2020) containing an electrolyte resin 17. In this embodiment, the electrolyte resin (corresponding to the “second electrolyte resin” in the present application) forming the electrolyte membrane 11 and the electrolyte resin (corresponding to the “first electrolyte resin” in the present application) included in the catalyst ink are Both are perfluorosulfonic acid electrolyte resins.

電解質膜１１と触媒インクとを用意した後、電解質膜１１の一方の面にアノード側触媒層１２ａを、もう一方の面にカソード側触媒層１２ｃを塗布する（ステップＳ２０）。本実施形態では、触媒層１２は、触媒インクをスプレー法により電解質膜１１に塗布することで形成する。白金１３の目付け量は、アノード側触媒層１２ａ側が０．２ｍｇ／ｃｍ2、カソード側触媒層１２ｃ側が０．４ｍｇ／ｃｍ2である。 After the electrolyte membrane 11 and the catalyst ink are prepared, the anode side catalyst layer 12a is applied to one surface of the electrolyte membrane 11, and the cathode side catalyst layer 12c is applied to the other surface (step S20). In the present embodiment, the catalyst layer 12 is formed by applying catalyst ink to the electrolyte membrane 11 by a spray method. Basis weight of the platinum 13, anode catalyst layer 12a side is 0.2 mg / cm 2, a cathode catalyst layer 12c side is 0.4 mg / cm 2.

次に、電解質膜１１と触媒層１２とを、水蒸気雰囲気下において、電解質樹脂１７のガラス転移点以上の温度で、接合する（ステップＳ３０）。一般的には、パーフルオロスルホン酸系の電解質樹脂１７のガラス転移点は、１１０度以上１４０度以下である。以降、電解質膜１１と触媒層１２とをガラス転移点以上の温度で接合するための熱処理を「接合熱処理」ともいう。この接合熱処理において、相対湿度は３０％から８０％であり、触媒層１２と電解質膜１１との接合圧力は、０．１ＭＰａ以上０．５ＭＰａ以下である。この圧力は、一般的なＭＥＡの作製時における接合圧力（おおよそ１ＭＰａ以上）と比較して低い圧力である。   Next, the electrolyte membrane 11 and the catalyst layer 12 are joined at a temperature equal to or higher than the glass transition point of the electrolyte resin 17 in a water vapor atmosphere (step S30). Generally, the glass transition point of the perfluorosulfonic acid electrolyte resin 17 is 110 degrees or more and 140 degrees or less. Hereinafter, the heat treatment for joining the electrolyte membrane 11 and the catalyst layer 12 at a temperature equal to or higher than the glass transition point is also referred to as “joining heat treatment”. In this bonding heat treatment, the relative humidity is 30% to 80%, and the bonding pressure between the catalyst layer 12 and the electrolyte membrane 11 is 0.1 MPa or more and 0.5 MPa or less. This pressure is lower than the joining pressure (approximately 1 MPa or more) at the time of manufacturing a general MEA.

電解質樹脂１７はガラス転移点以上になると絡み合いや結晶化が進むので、上述の方法によってＭＥＡ１０を作製すれば、電解質樹脂１７を含む触媒層１２の強度が向上する。また、本実施形態では、接合熱処理の温度の上限を、２００度としたため、スルホン酸基の分解を抑えることができる。よって、プロトンの伝導経路を確保しておくことができる。   Since the entanglement and crystallization proceed when the electrolyte resin 17 reaches the glass transition point or higher, the strength of the catalyst layer 12 including the electrolyte resin 17 is improved by forming the MEA 10 by the above-described method. Moreover, in this embodiment, since the upper limit of the temperature of joining heat processing was 200 degree | times, decomposition | disassembly of a sulfonic acid group can be suppressed. Therefore, a proton conduction path can be secured.

図３および図４は本実施形態による効果を説明するための図である。図３は、段階的に熱処理を行う場合を、図４は本実施形態により接合熱処理を行う場合を示している。本実施形態では、電解質膜１１に触媒層１２を形成し（ステップＳ２０）、その後に、接合熱処理を行う（ステップＳ３０）。図３に示すように、例えば、触媒層１２を拡散層２２に形成してガラス転移点を超える温度で第１の熱処理を行った後に（図３（Ａ））、触媒層１２を備える拡散層２２で電解質膜１１を狭持して第２の熱処理を行って接合することでも（図３（Ｂ））、触媒層１２の強度を向上させることはできる。しかし、そのように段階的に熱処理を行うと、第１の熱処理によって、触媒層１２において電解質樹脂１７の結晶化が進む。その結果、電解質膜１１と既に結晶化が進んだ触媒層１２とを接合することになるので、図３（Ｂ）に示すように電解質膜１１と触媒層１２との界面での抵抗が高くなり、発電性能が低下してしまう。   3 and 4 are diagrams for explaining the effect of this embodiment. FIG. 3 shows a case where heat treatment is performed in stages, and FIG. 4 shows a case where bonding heat treatment is performed according to the present embodiment. In the present embodiment, the catalyst layer 12 is formed on the electrolyte membrane 11 (step S20), and then a bonding heat treatment is performed (step S30). As shown in FIG. 3, for example, after the catalyst layer 12 is formed on the diffusion layer 22 and the first heat treatment is performed at a temperature exceeding the glass transition point (FIG. 3A), the diffusion layer including the catalyst layer 12 is provided. The strength of the catalyst layer 12 can also be improved by sandwiching the electrolyte membrane 11 at 22 and performing the second heat treatment (FIG. 3B). However, when heat treatment is performed in such a stepwise manner, the crystallization of the electrolyte resin 17 proceeds in the catalyst layer 12 by the first heat treatment. As a result, the electrolyte membrane 11 and the catalyst layer 12 that has already been crystallized are joined, so that the resistance at the interface between the electrolyte membrane 11 and the catalyst layer 12 is increased as shown in FIG. The power generation performance will be reduced.

これに対して、本実施形態では、前述の接合熱処理を電解質膜１１に触媒層１２を形成した後に行う。そのため、図４に示すように電解質膜１１と触媒層１２との界面において一体的に結晶化が進行するので、電解質膜１１と触媒層１２との界面抵抗の上昇を抑えることができる。さらに、本実施形態では、前述の接合熱処理により電解質膜１１と触媒層１２との界面で一体的に絡み合いや結晶化が進行するので、電解質膜１１と触媒層１２のそれぞれの備える電解質樹脂１７が絡み合うことになる。そのため、一般的なＭＥＡの作製時の接合圧力（おおよそ１ＭＰａ以上）と比較して低い圧力でも、十分な接合強度を得ることができる。よって、圧着時の触媒層１２や電解質膜１１の変形を抑制することができる。また、本実施形態では前述の接合熱処理を水蒸気雰囲気で行う。そのため、電解質膜１１および触媒層１２においては、接合熱処理による水分の揮発が抑制され、プロトンの伝導経路を確保することができる。よって、触媒層１１の強度の向上とプロトン伝導特性の向上とを両立させることができる。   On the other hand, in the present embodiment, the above-described bonding heat treatment is performed after the catalyst layer 12 is formed on the electrolyte membrane 11. Therefore, as shown in FIG. 4, since crystallization proceeds integrally at the interface between the electrolyte membrane 11 and the catalyst layer 12, an increase in the interface resistance between the electrolyte membrane 11 and the catalyst layer 12 can be suppressed. Further, in the present embodiment, since the entanglement and crystallization proceed integrally at the interface between the electrolyte membrane 11 and the catalyst layer 12 by the bonding heat treatment described above, the electrolyte resin 17 included in each of the electrolyte membrane 11 and the catalyst layer 12 is It will be intertwined. Therefore, sufficient bonding strength can be obtained even at a pressure lower than the bonding pressure (approximately 1 MPa or more) at the time of manufacturing a general MEA. Therefore, deformation of the catalyst layer 12 and the electrolyte membrane 11 at the time of pressure bonding can be suppressed. In this embodiment, the above-described bonding heat treatment is performed in a steam atmosphere. Therefore, in the electrolyte membrane 11 and the catalyst layer 12, volatilization of moisture due to the bonding heat treatment is suppressed, and a proton conduction path can be secured. Therefore, it is possible to achieve both improvement in the strength of the catalyst layer 11 and improvement in proton conduction characteristics.

Ｃ．単セルの発電試験
上述した接合熱処理の効果を調べるために、上述した製造方法におけるステップＳ３０の接合熱処理を行わなかったＭＥＡ１と、ステップＳ３０において水蒸気および有機溶媒を供給しないで接合熱処理を行ったＭＥＡ２と、ステップＳ１０からステップＳ３０により作製したＭＥＡ３とを用意した。ＭＥＡ２およびＭＥＡ３のステップＳ３０における接合温度は１６０度、接合圧力は０．３９ＭＰａである。次に、これらのＭＥＡ１、２、３を用いて単セル１、２、３を作製して、発電試験を行った。なお、単セル１、２、３を作製するにあたり、ＭＥＡ１、２、３ともにステップＳ２０において、触媒層１２を拡散層２２で狭持して、１００度、１．２ＭＰａの圧力で４分間圧着した。この圧着は、電解質樹脂１７のガラス転移点以下で行っているため、電解質樹脂１７の結晶化は進んでいない。 C. Single Cell Power Generation Test In order to investigate the effect of the above-described bonding heat treatment, MEA1 that did not perform the bonding heat treatment in step S30 in the above-described manufacturing method and MEA2 that performed the bonding heat treatment without supplying water vapor and an organic solvent in step S30 And MEA3 produced by step S10 to step S30 was prepared. The joining temperature in step S30 of MEA2 and MEA3 is 160 degrees, and the joining pressure is 0.39 MPa. Next, single cells 1, 2, and 3 were prepared using these MEAs 1, 2, and 3, and a power generation test was performed. In manufacturing the single cells 1, 2, and 3, in step S20, the MEA 1, 2, and 3 are both sandwiched between the catalyst layers 12 by the diffusion layer 22 and pressed at a pressure of 100 degrees and 1.2 MPa for 4 minutes. . Since this pressure bonding is performed below the glass transition point of the electrolyte resin 17, crystallization of the electrolyte resin 17 has not progressed.

図５は、単セル１、単セル２、単セル３を電流密度０．２Ａ／ｃｍ2において発電させた際のセル電圧の測定結果を示す図である。測定は、セル温度８０度、無加湿状態で行った。ステップＳ３０の接合熱処理を行わなかった単セル１と比べると、ガラス転移点以上で水蒸気を供給して接合熱処理を行った単セル３は、セル電圧が１８ｍＶ増加した。一方、ガラス転移点以上で水蒸気を供給せずに接合熱処理を行った単セル２は、接合熱処理を行わなかった単セル１と比較して、セル電圧が１６ｍＶ低下した。 FIG. 5 is a diagram showing measurement results of cell voltages when the single cell 1, single cell 2, and single cell 3 are generated at a current density of 0.2 A / cm 2 . The measurement was performed at a cell temperature of 80 degrees and in a non-humidified state. Compared with the single cell 1 that was not subjected to the bonding heat treatment in step S30, the cell voltage of the single cell 3 that was subjected to the bonding heat treatment by supplying water vapor above the glass transition point increased by 18 mV. On the other hand, the cell voltage of the single cell 2 that was subjected to the bonding heat treatment without supplying water vapor above the glass transition point was 16 mV lower than the single cell 1 that was not subjected to the bonding heat treatment.

単セル２は、ステップＳ３０における接合熱処理時に水蒸気が供給されていない。したがって、単セル２においては、触媒層１２の含水していた水分がガラス転移点を超える熱処理において揮発して、プロトンの伝導経路が減少した結果、単セル１と比較して発電性能が低下したと考えられる。一方、単セル３においては、水蒸気雰囲気下においてガラス転移点以上で接合しているため、プロトンの伝導経路を確保できており、単セル１と比較して発電性能が向上したと考えられる。以上の発電試験から、本実施形態で作製されたＭＥＡは、プロトン伝導特性が向上することを確認できた。   The unit cell 2 is not supplied with water vapor during the bonding heat treatment in step S30. Therefore, in the single cell 2, the moisture contained in the catalyst layer 12 is volatilized in the heat treatment exceeding the glass transition point, and the proton conduction path is reduced. As a result, the power generation performance is lowered as compared with the single cell 1. it is conceivable that. On the other hand, since the single cell 3 is bonded at a glass transition point or higher in a water vapor atmosphere, a proton conduction path can be secured, and power generation performance is considered to be improved as compared with the single cell 1. From the above power generation test, it was confirmed that the MEA produced in this embodiment has improved proton conduction characteristics.

Ｄ．変形例：
以上、本発明の一実施形態について説明したが、本発明はこのような実施形態に限定されず、その趣旨を逸脱しない範囲で種々の構成を採ることができる。 D. Variation:
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to such Embodiment, A various structure can be taken in the range which does not deviate from the meaning.

Ｄ１．変形例１：
上述の実施形態においては、電解質膜１１を形成する電解質樹脂１７と触媒インクに含まれる電解質樹脂１７は同じであるが、異なる電解質樹脂であってもよい。この場合、電解質膜１１を形成する電解質樹脂１７と触媒インクに含まれる電解質樹脂１７との両者のガラス転移点を超える温度で熱処理を行えば、上述の実施形態と同様に、電解質膜１１と触媒層１２との界面において界面抵抗が減少し、かつ電解質膜１１と触媒層１２との接合強度の高いＭＥＡ１０を得ることができる。 D1. Modification 1:
In the above-described embodiment, the electrolyte resin 17 forming the electrolyte membrane 11 and the electrolyte resin 17 included in the catalyst ink are the same, but different electrolyte resins may be used. In this case, if the heat treatment is performed at a temperature exceeding the glass transition point of both the electrolyte resin 17 forming the electrolyte membrane 11 and the electrolyte resin 17 included in the catalyst ink, the electrolyte membrane 11 and the catalyst are the same as in the above embodiment. It is possible to obtain the MEA 10 having a reduced interface resistance at the interface with the layer 12 and a high bonding strength between the electrolyte membrane 11 and the catalyst layer 12.

Ｄ２．変形例２：
上述の実施形態のステップＳ２０においては、触媒層１２は、触媒インクを電解質膜１１にスプレー法により塗布しているが、触媒層１２は、ドクターブレード法、スクリーン印刷法などによって電解質膜１１に塗布してもよい。また、触媒層１２は、電解質膜１１に直接塗布するのではなく、触媒インクを塗布した転写用のシートで電解質膜１１を狭持してガラス転移点未満の温度で熱処理した後に、シートを剥がすことによって、電解質膜１１の両側に形成してもよい。また、接合熱処理は、触媒インクを拡散層２２に塗布した後、その拡散層２２で電解質膜１１を狭持してから行ってもよい。さらに接合熱処理は、触媒インクを塗布した転写用のシートや拡散層２２による電解質膜１１の狭持と同時に行ってもよい。 D2. Modification 2:
In step S20 of the above-described embodiment, the catalyst layer 12 is coated with the catalyst ink on the electrolyte membrane 11 by the spray method, but the catalyst layer 12 is coated on the electrolyte membrane 11 by the doctor blade method, the screen printing method, or the like. May be. Further, the catalyst layer 12 is not directly applied to the electrolyte membrane 11, but the sheet is peeled after the electrolyte membrane 11 is sandwiched with a transfer sheet coated with catalyst ink and heat-treated at a temperature lower than the glass transition point. Thus, it may be formed on both sides of the electrolyte membrane 11. The bonding heat treatment may be performed after the catalyst ink is applied to the diffusion layer 22 and then the electrolyte membrane 11 is held between the diffusion layers 22. Further, the bonding heat treatment may be performed simultaneously with the holding of the electrolyte membrane 11 by the transfer sheet coated with the catalyst ink or the diffusion layer 22.

Ｄ３．変形例３：
上述の実施形態では、触媒として白金１３を用いているが、触媒としては例えば、金、銀、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウム等の貴金属や、鉄、ニッケル、マンガン、コバルト、クロム、銅、亜鉛、モリブデン、タングステン、ゲルマニウム、錫等の卑金属や、これら貴金属と卑金属との合金、また金属酸化物、金属錯体などの化合物を採用することもできる。 D3. Modification 3:
In the above-described embodiment, platinum 13 is used as the catalyst. Examples of the catalyst include noble metals such as gold, silver, ruthenium, rhodium, palladium, osmium, iridium, iron, nickel, manganese, cobalt, chromium, and copper. Base metals such as zinc, molybdenum, tungsten, germanium and tin, alloys of these noble metals and base metals, and compounds such as metal oxides and metal complexes can also be employed.

Ｄ４．変形例４：
上述の実施形態では、触媒としての白金１３をカーボン粒子が担持しているが、カーボン粒子に代えて、例えば、カーボンブラック、カーボンナノチューブ、カーボンナノファイバーなどの炭素材料のほか、炭化ケイ素などに代表される炭素化合物等を用いることができる。 D4. Modification 4:
In the above-described embodiment, carbon particles carry platinum 13 as a catalyst, but instead of carbon particles, for example, carbon materials such as carbon black, carbon nanotubes, carbon nanofibers, and silicon carbide are representative. The carbon compound etc. which are made can be used.

Ｄ５．変形例５：
上述の実施形態では、電解質膜１１としてＮａｆｉｏｎを用いているが、電解質膜１１としては、例えば、アシプレックス（登録商標）やフレミオン（登録商標）等の他のフッ素系スルホン酸膜が用いられるとしてもよい。 D5. Modification 5:
In the above-described embodiment, Nafion is used as the electrolyte membrane 11. However, as the electrolyte membrane 11, for example, other fluorine-based sulfonic acid membranes such as Aciplex (registered trademark) and Flemion (registered trademark) are used. Also good.

Ｄ６．変形例６：
上述の実施形態では、水蒸気雰囲気において電解質膜１１と触媒層１２との接合熱処理を行っているが、有機溶媒雰囲気や、水と有機溶媒とを含む雰囲気において行ってもよい。有機溶媒として、例えばエタノールなどを使用することができる。 D6. Modification 6:
In the above-described embodiment, the bonding heat treatment between the electrolyte membrane 11 and the catalyst layer 12 is performed in a water vapor atmosphere, but may be performed in an organic solvent atmosphere or an atmosphere containing water and an organic solvent. For example, ethanol or the like can be used as the organic solvent.

１１…電解質膜
１２…触媒層
１２ａ…アノード側触媒層
１２ｃ…カソード側触媒層
１３…白金
１６…触媒担体
１７…電解質樹脂
２２…拡散層
２２ａ…アノード側ガス拡散層
２２ｃ…カソード側ガス拡散層
３０…単セル
３３ａ…アノード側セパレータ
３３ｃ…カソード側セパレータ
３４ａ…燃料ガス流路
３４ｃ…酸化剤ガス流路
１００…燃料電池 DESCRIPTION OF SYMBOLS 11 ... Electrolyte membrane 12 ... Catalyst layer 12a ... Anode side catalyst layer 12c ... Cathode side catalyst layer 13 ... Platinum 16 ... Catalyst support 17 ... Electrolyte resin 22 ... Diffusion layer 22a ... Anode side gas diffusion layer 22c ... Cathode side gas diffusion layer 30 ... Single cell 33a ... Anode side separator 33c ... Cathode side separator 34a ... Fuel gas channel 34c ... Oxidant gas channel 100 ... Fuel cell

Claims (2)

膜電極接合体の製造方法であって、
第１の電解質樹脂を含む触媒層を、第２の電解質樹脂を含む電解質膜上に形成して膜電極接合体を作製する工程と、
水又は有機溶媒を含む雰囲気において、前記作製された膜電極接合体の前記触媒層と前記電解質膜とを、前記第１の電解質樹脂および前記第２の電解質樹脂のガラス転移点以上の温度で、前記触媒層と前記電解質膜とに、０．１ＭＰａ以上０．５ＭＰａ以下の圧力を加えて熱処理する工程と、
を備える膜電極接合体の製造方法。 A method for producing a membrane electrode assembly, comprising:
Forming a membrane electrode assembly by forming a catalyst layer containing a first electrolyte resin on an electrolyte membrane containing a second electrolyte resin ;
In an atmosphere containing water or an organic solvent, the fabricated membrane electrode assembly wherein the catalyst layer of said electrolyte membrane, in the first electrolyte resin and the second temperature higher than the glass transition point of the electrolyte resin, A step of heat-treating the catalyst layer and the electrolyte membrane by applying a pressure of 0.1 MPa or more and 0.5 MPa or less ;
The manufacturing method of a membrane electrode assembly provided with this. 請求項１に記載の製造方法であって、
前記ガラス転移点は１１０度以上１４０度以下であり、前記温度は２００度以下である、製造方法。 A method of manufacturing a mounting serial to claim 1,
The glass transition point is 110 degrees or more and 140 degrees or less, and the temperature is 200 degrees or less.
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JP5330060B2 (en) * 2009-03-31 2013-10-30 本田技研工業株式会社 Manufacturing method of membrane electrode assembly

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