JP2005268044A - Oxygen electrode for solid polymer fuel cell, and its manufacturing method therefor - Google Patents
Oxygen electrode for solid polymer fuel cell, and its manufacturing method therefor Download PDFInfo
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Abstract
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本発明は、固体高分子型燃料電池の酸素極およびその製造方法に関する。 The present invention relates to an oxygen electrode for a polymer electrolyte fuel cell and a method for producing the same.
ガスの電気化学反応により電気を発生させる燃料電池は、発電効率が高く、排出されるガスがクリーンで環境に対する影響が極めて少ない。そのため、近年、発電用、低公害の自動車用電源等、種々の用途が期待されている。 A fuel cell that generates electricity by an electrochemical reaction of gas has high power generation efficiency, clean gas discharged, and extremely little influence on the environment. Therefore, in recent years, various uses such as power generation and low-pollution automobile power supplies are expected.
なかでも、固体高分子型燃料電池は、８０℃程度の低温で作動させることができ、大きな出力密度を有する。固体高分子型燃料電池は、通常、プロトン伝導性のある高分子膜を電解質とする。電解質となる高分子膜（電解質膜）の両側にそれぞれ燃料極、酸素極となる一対の電極が設けられ電解質膜電極接合体（ＭＥＡ）が構成される。この電解質膜電極接合体をセパレータで挟持した単セルが発電単位となる。そして、水素や炭化水素等の燃料ガスを燃料極に、酸素や空気等の酸化剤ガスを酸素極にそれぞれ供給し、ガスと電解質と電極との三相界面における電気化学反応により発電を行う。 Among these, the polymer electrolyte fuel cell can be operated at a low temperature of about 80 ° C. and has a large output density. In the polymer electrolyte fuel cell, a proton conductive polymer membrane is usually used as an electrolyte. A pair of electrodes each serving as a fuel electrode and an oxygen electrode are provided on both sides of a polymer film (electrolyte film) serving as an electrolyte to form an electrolyte membrane electrode assembly (MEA). A single cell in which the electrolyte membrane electrode assembly is sandwiched between separators serves as a power generation unit. Then, a fuel gas such as hydrogen or hydrocarbon is supplied to the fuel electrode, and an oxidant gas such as oxygen or air is supplied to the oxygen electrode, and power is generated by an electrochemical reaction at the three-phase interface between the gas, the electrolyte, and the electrode.
通常、電解質膜には、イオン伝導性が高く化学的にも安定であるという理由から、全フッ素系スルホン酸膜等のカチオン交換樹脂膜が使用される。また、プロトン伝導経路の確保のため、電極中にも電解質膜と同種の電解質が含有される。このため、電池セル内は強酸性雰囲気となり、酸素極では酸素還元反応［Ｏ2＋４Ｈ+＋４ｅ-→２Ｈ2Ｏ］が進行し難い。また、強酸性雰囲気で使用できる触媒は少なく、触媒に高価な白金を用いなければならないのが現状である。 Usually, a cation exchange resin membrane such as a perfluorinated sulfonic acid membrane is used for the electrolyte membrane because it has high ion conductivity and is chemically stable. In order to secure a proton conduction path, the electrode also contains the same type of electrolyte as the electrolyte membrane. For this reason, the inside of the battery cell becomes a strongly acidic atmosphere, and the oxygen reduction reaction [O 2 + 4H + + 4e − → 2H 2 O] hardly proceeds at the oxygen electrode. In addition, there are few catalysts that can be used in a strongly acidic atmosphere, and the present situation is that expensive platinum must be used as the catalyst.
一方、電解質にアルカリ水溶液を用いるアルカリ型燃料電池では、電池セル内が強塩基性となるため、酸素極での酸素還元反応［Ｏ2＋２Ｈ2Ｏ＋４ｅ-→４ＯＨ-］が進行し易く、ニッケル、銀等の比較的安価な金属を使用できるという利点がある。しかし、アルカリ水溶液の保持が難しい等の欠点もある。そこで、アルカリ型燃料電池では、電解質にアニオン交換樹脂を使用する試みがなされている。 On the other hand, in an alkaline fuel cell that uses an alkaline aqueous solution as the electrolyte, the inside of the battery cell is strongly basic, so that the oxygen reduction reaction [O 2 + 2H 2 O + 4e − → 4OH − ] at the oxygen electrode is likely to proceed. There is an advantage that a relatively inexpensive metal such as silver can be used. However, there is a drawback that it is difficult to maintain the alkaline aqueous solution. Thus, in an alkaline fuel cell, an attempt has been made to use an anion exchange resin as an electrolyte.
また、電解質膜にカチオン交換樹脂膜とアニオン交換樹脂膜とを使用したバイポーラ型の燃料電池が提案されている（例えば、特許文献１、２参照。）。バイポーラ型燃料電池では、電解質膜中、つまりカチオン交換樹脂膜とアニオン交換樹脂膜との接合界面で水が生成する。このため、電解質膜の乾燥が抑制される。
しかしながら、アニオン交換樹脂膜は、カチオン交換樹脂膜と比較して、イオン伝導性が低く、化学的安定性も充分とはいえない。このため、アニオン交換樹脂膜を電解質膜として用いた場合、充分な電池性能を得ることは難しい。 However, the anion exchange resin membrane has a lower ion conductivity than the cation exchange resin membrane, and the chemical stability is not sufficient. For this reason, when an anion exchange resin membrane is used as an electrolyte membrane, it is difficult to obtain sufficient battery performance.
また、上記バイポーラ型燃料電池の酸素極では、アニオン交換樹脂膜との界面にて、次式（１）で表される酸素還元反応が進行する。
Ｏ2＋２Ｈ2Ｏ＋４ｅ-→４ＯＨ-・・・（１）
式（１）に示すように、酸素極の反応には水が必要となる。このため、運転条件によっては、酸素極の反応に電解質膜中で生成した水が必要となり、この場合、電解質膜からの水の移動が律速となる。また、カチオン交換樹脂膜とアニオン交換樹脂膜との接合界面が平面的であるため、水の生成サイトが少なく、反応が律速される。さらに、電解質膜中で過剰に水が生成した場合には、排出することが難しいという問題もある。
In the oxygen electrode of the bipolar fuel cell, an oxygen reduction reaction represented by the following formula (1) proceeds at the interface with the anion exchange resin membrane.
O 2 + 2H 2 O + 4e − → 4OH − (1)
As shown in Formula (1), water is required for the reaction of the oxygen electrode. For this reason, depending on the operating conditions, water generated in the electrolyte membrane is required for the reaction of the oxygen electrode. In this case, the movement of water from the electrolyte membrane is rate-limiting. In addition, since the bonding interface between the cation exchange resin membrane and the anion exchange resin membrane is planar, the number of water generation sites is small and the reaction is rate limited. Furthermore, when water is excessively generated in the electrolyte membrane, there is a problem that it is difficult to discharge.
本発明は、このような実状に鑑みてなされたものであり、電池性能が高く、水管理性に優れた固体高分子型燃料電池を構成することのできる酸素極およびその製造方法を提供することを課題とする。 The present invention has been made in view of such a situation, and provides an oxygen electrode capable of constituting a polymer electrolyte fuel cell having high battery performance and excellent water management, and a method for producing the same. Is an issue.
本発明の固体高分子型燃料電池用酸素極は、酸素極触媒と、アニオン交換樹脂と、カチオン交換樹脂とを含み、該アニオン交換樹脂は、該酸素極触媒を被覆するよう配置され、該カチオン交換樹脂は、該アニオン交換樹脂と接するよう配置された触媒層を持つ。 The oxygen electrode for a polymer electrolyte fuel cell of the present invention includes an oxygen electrode catalyst, an anion exchange resin, and a cation exchange resin, and the anion exchange resin is disposed so as to cover the oxygen electrode catalyst, and the cation The exchange resin has a catalyst layer disposed so as to be in contact with the anion exchange resin.
一般に、電極は、触媒層と拡散層とから構成される。触媒層は、電解質膜の表面に形成され、電気化学反応の反応場となる。拡散層は、触媒層の表面に積層して形成され、触媒層への反応ガスの供給と、触媒層との間で電子の授受を行う役割を果たす。 In general, an electrode is composed of a catalyst layer and a diffusion layer. The catalyst layer is formed on the surface of the electrolyte membrane and serves as a reaction field for electrochemical reaction. The diffusion layer is formed by being laminated on the surface of the catalyst layer, and plays a role of supplying a reaction gas to the catalyst layer and transferring electrons between the catalyst layer.
本発明の酸素極では、触媒層中の酸素極触媒がアニオン交換樹脂で被覆される。このため、酸素極触媒の周囲は塩基性雰囲気となり、上述した式（１）で表される酸素還元反応が進行する。一方、燃料極では、従来と同様に次式（２）で表される水素酸化反応が進行する。
２Ｈ2→４Ｈ2 +＋４ｅ-・・・（２）
燃料極で生成したプロトンは、電解質膜の中を移動して酸素極に達し、さらに酸素極のカチオン交換樹脂を通って、カチオン交換樹脂とアニオン交換樹脂との界面に到達する。そして、両樹脂の界面で次式（３）の反応により水を生成する。
４Ｈ2 +＋４ＯＨ-→４Ｈ2Ｏ・・・（３）
なお、電池内で起きる全反応は次式（４）となり、従来の電池反応と変わらない。
２Ｈ2＋Ｏ2→２Ｈ2Ｏ・・・（４）
このように、本発明の酸素極では、塩基性雰囲気となるため、酸素極触媒の活性が高い。よって、式（１）で示される酸素還元反応が速やかに進行する。また、反応に必要な水は酸素極内で生成されるため、水の移動が律速になることはない。さらに、塩基性雰囲気となることで、アルカリ型燃料電池で使用されるニッケル、銀等の比較的安価な金属を、酸素極触媒として使用することが可能となる。これより、酸素極触媒の選択の幅が広がるとともに、コストを大幅に削減することができる。
In the oxygen electrode of the present invention, the oxygen electrode catalyst in the catalyst layer is coated with an anion exchange resin. For this reason, the oxygen electrode catalyst has a basic atmosphere, and the oxygen reduction reaction represented by the above-described formula (1) proceeds. On the other hand, in the fuel electrode, the hydrogen oxidation reaction represented by the following formula (2) proceeds as in the conventional case.
2H 2 → 4H 2 + + 4e − (2)
Protons generated at the fuel electrode move through the electrolyte membrane to reach the oxygen electrode, and further pass through the cation exchange resin of the oxygen electrode to reach the interface between the cation exchange resin and the anion exchange resin. And water is produced | generated by reaction of following Formula (3) in the interface of both resin.
4H 2 + + 4OH − → 4H 2 O (3)
The total reaction occurring in the battery is represented by the following formula (4), which is not different from the conventional battery reaction.
2H 2 + O 2 → 2H 2 O (4)
Thus, the oxygen electrode of the present invention has a basic atmosphere, so the activity of the oxygen electrode catalyst is high. Accordingly, the oxygen reduction reaction represented by the formula (1) proceeds promptly. In addition, since water necessary for the reaction is generated in the oxygen electrode, the movement of water is not rate-limiting. Furthermore, it becomes possible to use comparatively cheap metals, such as nickel and silver used with an alkaline fuel cell, as an oxygen electrode catalyst by becoming basic atmosphere. As a result, the range of selection of the oxygen electrode catalyst is widened, and the cost can be greatly reduced.
また、本発明の酸素極では、カチオン交換樹脂がアニオン交換樹脂に接するように配置される。つまり、カチオン交換樹脂が、酸素極触媒を被覆したアニオン交換樹脂の周りに配置される。このため、アニオン交換樹脂とカチオン交換樹脂との界面が三次元的に形成され、水の生成サイトが増加する。一方、酸素極で過剰に生成した水は、酸素極を通過する酸化剤ガスにより気化され、速やかに排出される。このため、生成水により酸素極の空孔が閉塞されるおそれは少ない。また、本発明の酸素極は、カチオン交換樹脂を含むため、従来のカチオン交換樹脂からなる電解質膜との接合性も良好である。 Moreover, in the oxygen electrode of this invention, it arrange | positions so that a cation exchange resin may contact | connect an anion exchange resin. That is, the cation exchange resin is disposed around the anion exchange resin coated with the oxygen electrode catalyst. For this reason, the interface of an anion exchange resin and a cation exchange resin is formed in three dimensions, and the production site of water increases. On the other hand, the water generated excessively at the oxygen electrode is vaporized by the oxidant gas passing through the oxygen electrode and quickly discharged. For this reason, there is little possibility that the vacancies of the oxygen electrode are blocked by the generated water. In addition, since the oxygen electrode of the present invention contains a cation exchange resin, the bonding property with an electrolyte membrane made of a conventional cation exchange resin is also good.
本発明の固体高分子型燃料電池用酸素極形成方法は、酸素極触媒がアニオン交換樹脂で被覆されてなるアニオン交換樹脂被覆触媒と、カチオン交換樹脂と、を含む触媒層形成用粉末を準備する触媒層形成用粉末準備工程と、該触媒層形成用粉末を電解質膜の表面に付着させ、熱圧着することにより該電解質膜の表面に触媒層を形成する触媒層形成工程と、を含む。 The method for forming an oxygen electrode for a polymer electrolyte fuel cell according to the present invention provides a catalyst layer forming powder comprising an anion exchange resin-coated catalyst in which an oxygen electrode catalyst is coated with an anion exchange resin, and a cation exchange resin. A catalyst layer forming powder preparation step, and a catalyst layer forming step in which the catalyst layer forming powder is attached to the surface of the electrolyte membrane and thermocompression bonded to form a catalyst layer on the surface of the electrolyte membrane.
本発明の固体高分子型燃料電池用酸素極形成方法では、触媒層形成用粉末を用いて触媒層を形成する。触媒層形成用粉末において、酸素極触媒はアニオン交換樹脂で被覆されている。このような触媒層形成用粉末を用いることで、上記本発明の酸素極を簡便に形成することができる。 In the method for forming an oxygen electrode for a polymer electrolyte fuel cell of the present invention, the catalyst layer is formed using the catalyst layer forming powder. In the catalyst layer forming powder, the oxygen electrode catalyst is coated with an anion exchange resin. By using such a catalyst layer forming powder, the oxygen electrode of the present invention can be easily formed.
本発明の固体高分子型燃料電池は、上記本発明の酸素極と、水素を含む燃料ガスが供給される燃料極と、該酸素極と該燃料極との間に挟装された電解質膜と、を備える。上述したように、本発明の酸素極では、塩基性雰囲気、かつ、反応場となるアニオン交換樹脂とカチオン交換樹脂との界面の増加により、電池反応が活性化される。一方、酸素極で過剰に生成した水は、速やかに排出される。このように、本発明の酸素極を備える本発明の固体高分子型燃料電池は、電池性能および水管理性に優れる。 The polymer electrolyte fuel cell according to the present invention includes the oxygen electrode according to the present invention, a fuel electrode to which a fuel gas containing hydrogen is supplied, and an electrolyte membrane sandwiched between the oxygen electrode and the fuel electrode. . As described above, in the oxygen electrode of the present invention, the battery reaction is activated due to the increase in the basic atmosphere and the interface between the anion exchange resin and the cation exchange resin serving as a reaction field. On the other hand, water generated excessively at the oxygen electrode is quickly discharged. Thus, the polymer electrolyte fuel cell of the present invention provided with the oxygen electrode of the present invention is excellent in cell performance and water manageability.
例えば、燃料極に高湿の燃料ガスが供給され、酸素極に低湿の酸化剤ガスが供給されるような運転条件では、電解質膜には充分な水が供給されるとともに、生成水の排出は速やかに行われる。このような条件下では、本発明の固体高分子型燃料電池の長所が効果的に発揮される。また、電解質膜として、従来のカチオン交換樹脂膜を使用できるため、高い電池性能を得ることができる。この場合、電解質膜を、酸素極に含有させるカチオン交換樹脂製の膜とすることで、酸素極と電解質膜との接合性も良好となる。 For example, in an operating condition in which a high-humidity fuel gas is supplied to the fuel electrode and a low-humidity oxidant gas is supplied to the oxygen electrode, sufficient water is supplied to the electrolyte membrane and the generated water is discharged. Promptly. Under such conditions, the advantages of the polymer electrolyte fuel cell of the present invention are effectively exhibited. Moreover, since a conventional cation exchange resin membrane can be used as the electrolyte membrane, high battery performance can be obtained. In this case, when the electrolyte membrane is a membrane made of a cation exchange resin to be contained in the oxygen electrode, the bondability between the oxygen electrode and the electrolyte membrane is improved.
本発明の固体高分子型燃料電池用酸素極では、塩基性雰囲気にて、酸素還元反応を進行させる。これより、酸素極触媒の選択の幅を広げることができる。また、アニオン交換樹脂とカチオン交換樹脂との界面が三次元的に形成されるため、電池反応が活性化される。一方、過剰に生成した水は、酸素極を通過する酸化剤ガスにより気化され、速やかに排出される。このため、水管理性が良い。また、本発明の酸素極形成方法によれば、本発明の酸素極を簡便に形成することができる。 In the oxygen electrode for a polymer electrolyte fuel cell of the present invention, the oxygen reduction reaction proceeds in a basic atmosphere. Thereby, the range of selection of the oxygen electrode catalyst can be expanded. Further, since the interface between the anion exchange resin and the cation exchange resin is formed three-dimensionally, the battery reaction is activated. On the other hand, the excessively generated water is vaporized by the oxidant gas passing through the oxygen electrode and is quickly discharged. For this reason, water management nature is good. In addition, according to the oxygen electrode forming method of the present invention, the oxygen electrode of the present invention can be easily formed.
以下に、本発明の固体高分子型燃料電池用酸素極、その形成方法、およびそれを用いた固体高分子型燃料電池の実施形態を順に説明する。 Hereinafter, embodiments of an oxygen electrode for a polymer electrolyte fuel cell, a method for forming the same, and a polymer electrolyte fuel cell using the same according to the present invention will be described in order.
〈固体高分子型燃料電池用酸素極〉
本発明の固体高分子型燃料電池用酸素極は、酸素極触媒と、アニオン交換樹脂と、カチオン交換樹脂とを含み、該アニオン交換樹脂は、該酸素極触媒を被覆するよう配置され、該カチオン交換樹脂は、該アニオン交換樹脂と接するよう配置された触媒層を持つ。
<Oxygen electrode for polymer electrolyte fuel cells>
The oxygen electrode for a polymer electrolyte fuel cell of the present invention includes an oxygen electrode catalyst, an anion exchange resin, and a cation exchange resin, and the anion exchange resin is disposed so as to cover the oxygen electrode catalyst, and the cation The exchange resin has a catalyst layer disposed so as to be in contact with the anion exchange resin.
酸素極触媒は、通常用いられる白金、白金とニッケル、コバルト、鉄等との合金の他、ニッケル、銀、Ｃｏ−ＴＴＰ（Co-Tetraphenyl-porphyrin）等の有機金属錯体、Ｌａ1-xＳｒxＭＯ3（Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ）等のＬａ系ペロブスカイトを用いることができる。これらの粒子を、例えばカーボン等に担持させて酸素極触媒とすればよい。 Examples of the oxygen electrode catalyst include platinum, platinum-nickel, cobalt, iron, and other commonly used alloys, as well as organometallic complexes such as nickel, silver, and Co-TTP (Co-Tetraphenyl-porphyrin), La 1-x Sr x. La-based perovskites such as MO 3 (M: Co, Ni, Mn, Fe) can be used. These particles may be supported on, for example, carbon to form an oxygen electrode catalyst.
アニオン交換樹脂は、上記酸素極触媒を被覆するよう配置される。この場合、酸素極触媒の表面は、すべてアニオン交換樹脂で被覆されることが望ましい。しかし、酸素極触媒の表面に、アニオン交換樹脂で被覆されない部分があっても構わない。 The anion exchange resin is disposed so as to cover the oxygen electrode catalyst. In this case, the entire surface of the oxygen electrode catalyst is preferably coated with an anion exchange resin. However, there may be a portion not covered with the anion exchange resin on the surface of the oxygen electrode catalyst.
アニオン交換樹脂は、アニオン（水酸イオンＯＨ-）を移動させることのできる種々の樹脂を用いることができる。例えば、下記一般式（ａ）で表されるスチレン−ビニルベンジルトリアルキルアンモニウム共重合体、一般式（ｂ）で表されるＮ，Ｎ−ジアルキルアルキレンアンモニウム、一般式（ｃ）で表されるポリビニルベンジルトリアルキルアンモニウム（ＰＶＢＴＭＡ）、一般式（ｄ）で表されるポリビニルアルキルトリアルキルアンモニウム、一般式（ｅ）で表されるアルキレン−ビニルアルキレントリアルキルアンモニウム共重合体等が挙げられる。特に、化学的安定性に優れるという理由から、一般式（ａ）で表されるスチレン−ビニルベンジルトリアルキルアンモニウム共重合体、一般式（ｃ）で表されるＰＶＢＴＭＡが好適である。 As the anion exchange resin, various resins capable of moving anions (hydroxyl ions OH − ) can be used. For example, styrene-vinylbenzyltrialkylammonium copolymer represented by the following general formula (a), N, N-dialkylalkyleneammonium represented by the general formula (b), polyvinyl represented by the general formula (c) Examples thereof include benzyltrialkylammonium (PVBTMA), polyvinylalkyltrialkylammonium represented by the general formula (d), and an alkylene-vinylalkylenetrialkylammonium copolymer represented by the general formula (e). In particular, a styrene-vinylbenzyltrialkylammonium copolymer represented by the general formula (a) and PVBTMA represented by the general formula (c) are preferable because of excellent chemical stability.
カチオン交換樹脂は、上記アニオン交換樹脂と接するよう配置される。つまり、触媒層において、酸素極触媒を被覆したアニオン交換樹脂の周りに配置される。カチオン交換樹脂は、カチオン（プロトンＨ+）を移動させることのできる種々の樹脂を用いることができる。例えば、スルホン酸樹脂、ホスホン酸樹脂、カルボン酸樹脂、イミド樹脂等が好適である。 The cation exchange resin is disposed in contact with the anion exchange resin. That is, the catalyst layer is disposed around the anion exchange resin coated with the oxygen electrode catalyst. As the cation exchange resin, various resins capable of transferring a cation (proton H + ) can be used. For example, a sulfonic acid resin, a phosphonic acid resin, a carboxylic acid resin, an imide resin, and the like are preferable.
スルホン酸樹脂としては、「ナフィオン」（登録商標、デュポン社製）、「アシプレックス」（登録商標、旭化成株式会社製）、「フレミオン」（登録商標、旭硝子株式会社製）等として知られる四フッ化エチレン−パーフルオロビニルエーテルスルホン酸共重合体、ポリスチレンスルホン酸、架橋ポリスチレンスルホン酸、エチレンテトラフルオロエチレン共重合体−ｇ−ポリスチレンスルホン酸、スルホン化ポリアリレーンエーテルエーテルケトン、スルホン化ポリアリレーンエーテルスルホン、ポリトリフルオロスチレンスルホン酸、スルホン化ポリ（２，３ジフェニル−１，４フェニレンオキシド）樹脂、スルホン化ポリベンジルシラン樹脂、スルホン化ポリイミド樹脂、ポリビニルスルホン酸、スルホン化フェノール樹脂、スルホン化ポリアミド樹脂等が挙げられる。 Examples of the sulfonic acid resin include four fluorines known as “Nafion” (registered trademark, manufactured by DuPont), “Aciplex” (registered trademark, manufactured by Asahi Kasei Co., Ltd.), “Flemion” (registered trademark, manufactured by Asahi Glass Co., Ltd.), and the like. Ethylene-perfluorovinyl ether sulfonic acid copolymer, polystyrene sulfonic acid, cross-linked polystyrene sulfonic acid, ethylene tetrafluoroethylene copolymer-g-polystyrene sulfonic acid, sulfonated polyarylene ether ether ketone, sulfonated polyarylene ether Sulfone, polytrifluorostyrene sulfonic acid, sulfonated poly (2,3diphenyl-1,4phenylene oxide) resin, sulfonated polybenzylsilane resin, sulfonated polyimide resin, polyvinyl sulfonic acid, sulfonated phenol resin, sulfone Polyamide resins.
ホスホン酸樹脂としては、四フッ化エチレン−パーフルオロビニルエーテルホスホン酸共重合体、ポリスチレンホスホン酸、架橋ポリスチレンホスホン酸、ポリビニルベンジルホスホン酸、エチレンテトラフルオロエチレン共重合体−ｇ−ポリスチレンホスホン酸、ホスホン酸化ポリアリレーンエーテルエーテルケトン、ホスホン酸化ポリアリレーンエーテルスルホン、ポリトリフルオロスチレンホスホン酸、ホスホン酸化ポリ（２，３ジフェニル−１，４フェニレンオキシド）樹脂、ホスホン酸化ポリベンジルシラン樹脂、ホスホン酸化ポリイミド樹脂、ポリビニルホスホン酸、ホスホン酸化フェノール樹脂、ホスホン酸化ポリアミド樹脂、ポリベンズイミダゾールりん酸複合樹脂等が挙げられる。 Examples of phosphonic acid resins include tetrafluoroethylene-perfluorovinyl ether phosphonic acid copolymer, polystyrene phosphonic acid, cross-linked polystyrene phosphonic acid, polyvinyl benzyl phosphonic acid, ethylene tetrafluoroethylene copolymer-g-polystyrene phosphonic acid, phosphonated Polyarylene ether ether ketone, phosphonated polyarylene ether sulfone, polytrifluorostyrene phosphonic acid, phosphonated poly (2,3diphenyl-1,4phenylene oxide) resin, phosphonated polybenzylsilane resin, phosphonated polyimide resin , Polyvinylphosphonic acid, phosphonated phenol resin, phosphonated polyamide resin, polybenzimidazole phosphoric acid composite resin, and the like.
カルボン酸樹脂としては、四フッ化エチレン−パーフルオロビニルエーテルカルボン酸共重合体、ポリビニル安息香酸、架橋ポリビニル安息香酸、エチレンテトラフルオロエチレン共重合体−ｇ−ポリビニル安息香酸、カルボン酸化ポリアリレーンエーテルエーテルケトン、カルボン酸化ポリアリレーンエーテルスルホン、ポリトリフルオロスチレンカルボン酸、カルボン酸化ポリ（２，３ジフェニル−１，４フェニレンオキシド）樹脂、カルボン酸化ポリベンジルシラン樹脂、カルボン酸化ポリイミド樹脂等が挙げられる。 Examples of the carboxylic acid resin include tetrafluoroethylene-perfluorovinyl ether carboxylic acid copolymer, polyvinyl benzoic acid, cross-linked polyvinyl benzoic acid, ethylene tetrafluoroethylene copolymer-g-polyvinyl benzoic acid, and carboxylated polyarylene ether ether. Examples include ketones, carboxylated polyarylene ether sulfones, polytrifluorostyrene carboxylic acids, carboxylated poly (2,3diphenyl-1,4phenylene oxide) resins, carboxylated polybenzylsilane resins, and carboxylated polyimide resins.
イミド樹脂としては、四フッ化エチレン−パーフルオロビニルエーテルスルホンイミド酸共重合体、ポリスチレントリフルオロメチルスルホンイミド等が挙げられる。 Examples of the imide resin include tetrafluoroethylene-perfluorovinyl ether sulfonimide acid copolymer, polystyrene trifluoromethyl sulfonimide, and the like.
カチオン交換樹脂は、後述する電解質膜に用いる樹脂と同種であることが望ましい。電解質膜と同種の樹脂を酸素極に配置することで、酸素極と電解質膜との接合性が良好となり、プロトン伝導性が向上する。よって、カチオン交換樹脂は、使用する電解質膜の種類を考慮して、適宜選択すればよい。 The cation exchange resin is desirably the same type as the resin used for the electrolyte membrane described later. By disposing the same type of resin as the electrolyte membrane on the oxygen electrode, the bondability between the oxygen electrode and the electrolyte membrane is improved, and proton conductivity is improved. Therefore, the cation exchange resin may be appropriately selected in consideration of the type of electrolyte membrane to be used.
本発明の酸素極の形成方法は、特に限定されるものではない。例えば、以下に示す本発明の方法により、簡便に形成することができる。 The method for forming the oxygen electrode of the present invention is not particularly limited. For example, it can be easily formed by the method of the present invention described below.
〈固体高分子型燃料電池用酸素極形成方法〉
本発明の固体高分子型燃料電池用酸素極形成方法は、触媒層形成用粉末準備工程と、触媒層形成工程と、を含む。以下、各工程について説明する。
<Method for forming oxygen electrode for polymer electrolyte fuel cell>
The method for forming an oxygen electrode for a polymer electrolyte fuel cell according to the present invention includes a catalyst layer forming powder preparation step and a catalyst layer forming step. Hereinafter, each step will be described.
（１）触媒層形成用粉末準備工程
本工程は、酸素極触媒がアニオン交換樹脂で被覆されてなるアニオン交換樹脂被覆触媒と、カチオン交換樹脂と、を含む触媒層形成用粉末を準備する工程である。
(1) Catalyst layer forming powder preparation step This step is a step of preparing a catalyst layer forming powder including an anion exchange resin-coated catalyst in which an oxygen electrode catalyst is coated with an anion exchange resin, and a cation exchange resin. is there.
触媒層形成用粉末は、酸素極触媒がアニオン交換樹脂で被覆されたアニオン交換樹脂被覆触媒と、カチオン交換樹脂とを含んでいればよく、その製造方法により種々の態様をとり得る。以下（ａ）〜（ｅ）に、触媒層形成用粉末の好適な製造方法を説明する。 The powder for forming the catalyst layer only needs to contain an anion exchange resin-coated catalyst in which an oxygen electrode catalyst is coated with an anion exchange resin and a cation exchange resin, and can take various forms depending on the production method. Hereinafter, (a) to (e) will be described a preferred method for producing the catalyst layer forming powder.
（ａ）酸素極触媒をアニオン交換樹脂で被覆したアニオン交換樹脂被覆触媒の粉末を予め製造し、該粉末とカチオン交換樹脂の粉末とを混合して触媒層形成用粉末を得ることができる。つまり、アニオン交換樹脂被覆触媒粉末とカチオン交換樹脂粉末との混合粉末が、触媒層形成用粉末となる。この場合、アニオン交換樹脂被覆触媒の粉末は、例えば、アニオン交換樹脂を水等の溶媒に溶解させたアニオン交換樹脂溶液に、酸素極触媒の粉末を分散させ、この分散液をスプレードライ等により乾燥して製造することができる。 (A) An anion exchange resin-coated catalyst powder in which an oxygen electrode catalyst is coated with an anion exchange resin is produced in advance, and the powder and a cation exchange resin powder are mixed to obtain a powder for forming a catalyst layer. That is, the mixed powder of the anion exchange resin-coated catalyst powder and the cation exchange resin powder becomes the catalyst layer forming powder. In this case, the powder of the anion exchange resin-coated catalyst is obtained by, for example, dispersing the oxygen electrode catalyst powder in an anion exchange resin solution obtained by dissolving the anion exchange resin in a solvent such as water, and drying the dispersion by spray drying or the like. Can be manufactured.
（ｂ）アニオン交換樹脂が水溶性であり、カチオン交換樹脂が非水溶性の場合には、該アニオン交換樹脂を水に溶解させたアニオン交換樹脂水溶液に、酸素極触媒の粉末と非水溶性カチオン交換樹脂の粉末とを分散させ、この分散液をスプレードライ等により乾燥して触媒層形成用粉末を得ることができる。 (B) When the anion exchange resin is water-soluble and the cation exchange resin is water-insoluble, an anion exchange resin aqueous solution in which the anion exchange resin is dissolved in water is mixed with an oxygen electrode catalyst powder and a water-insoluble cation. The powder of the exchange resin can be dispersed, and this dispersion can be dried by spray drying or the like to obtain a catalyst layer forming powder.
（ｃ）アニオン交換樹脂が非水溶性の場合には、該アニオン交換樹脂を水以外の溶媒に溶解させたアニオン交換樹脂溶液に、酸素極触媒の粉末とカチオン交換樹脂の粉末とを分散させ、この分散液をスプレードライ等により乾燥して触媒層形成用粉末を得ることができる。この場合、アニオン交換樹脂を溶解させる溶媒として、カチオン交換樹脂が溶解し難いものを選択する必要がある。例えば、アニオン交換樹脂として、前出一般式（ａ）で表されるスチレン−ビニルベンジルトリアルキルアンモニウム共重合体（ｍ／（ｍ＋ｎ）≦０．６）を、またカチオン交換樹脂として、四フッ化エチレン−パーフルオロビニルエーテルスルホン酸共重合体を用いた場合には、アニオン交換樹脂を溶解する溶媒にテトラヒドロフラン（ＴＨＦ）等を採用するとよい。 (C) When the anion exchange resin is water-insoluble, the oxygen electrode catalyst powder and the cation exchange resin powder are dispersed in an anion exchange resin solution obtained by dissolving the anion exchange resin in a solvent other than water. This dispersion can be dried by spray drying or the like to obtain a catalyst layer forming powder. In this case, it is necessary to select a solvent in which the cation exchange resin is difficult to dissolve as a solvent for dissolving the anion exchange resin. For example, a styrene-vinylbenzyltrialkylammonium copolymer (m / (m + n) ≦ 0.6) represented by the general formula (a) is used as an anion exchange resin, and tetrafluoride is used as a cation exchange resin. When an ethylene-perfluorovinyl ether sulfonic acid copolymer is used, tetrahydrofuran (THF) or the like may be employed as a solvent for dissolving the anion exchange resin.
（ｄ）また、アニオン交換樹脂が非水溶性の場合には、酸素極触媒をアニオン交換樹脂で被覆したアニオン交換樹脂被覆触媒の粉末を予め製造しておき、その粉末をカチオン交換樹脂を溶媒に溶解させたカチオン交換樹脂溶液に分散させ、この分散液をスプレードライ等により乾燥して触媒層形成用粉末を得ることができる。なお、カチオン交換樹脂を溶解する溶媒としては、水の他、アニオン交換樹脂を溶解し難い溶媒であれば何でもよい。 (D) When the anion exchange resin is water-insoluble, an anion exchange resin-coated catalyst powder in which an oxygen electrode catalyst is coated with an anion exchange resin is prepared in advance, and the powder is used as a solvent with the cation exchange resin as a solvent. The catalyst layer forming powder can be obtained by dispersing in a dissolved cation exchange resin solution and drying the dispersion by spray drying or the like. The solvent for dissolving the cation exchange resin may be any solvent other than water as long as it is difficult to dissolve the anion exchange resin.
（２）触媒層形成工程
本工程は、前の工程で準備した触媒層形成用粉末を、電解質膜の表面に付着させ、熱圧着することにより電解質膜の表面に触媒層を形成する工程である。
(2) Catalyst layer forming step This step is a step of forming the catalyst layer on the surface of the electrolyte membrane by attaching the catalyst layer forming powder prepared in the previous step to the surface of the electrolyte membrane and thermocompression bonding. .
使用する電解質膜の種類は、特に限定されるものではない。特に、カチオン交換樹脂膜は、アニオン交換樹脂膜と比較して、イオン伝導性および化学的安定性に優れるため好適である。カチオン交換樹脂膜を採用する場合には、上述したカチオン交換樹脂からなる膜を用いればよい。この場合、酸素極と電解質膜との接合性等の観点から、酸素極に含有させるカチオン交換樹脂と同種の樹脂を用いることが望ましい。 The kind of electrolyte membrane to be used is not particularly limited. In particular, the cation exchange resin membrane is preferable because it has excellent ion conductivity and chemical stability as compared with the anion exchange resin membrane. When employing a cation exchange resin membrane, a membrane made of the cation exchange resin described above may be used. In this case, it is desirable to use the same type of resin as the cation exchange resin to be contained in the oxygen electrode from the viewpoint of the bondability between the oxygen electrode and the electrolyte membrane.
本工程では、電解質膜の表面に、上記触媒層形成用粉末を散布等して付着させた後、熱圧着する。熱圧着の条件は、使用する樹脂の種類等に応じて適宜決定すればよい。例えば、温度を８０〜１３０℃程度、圧力を０．５〜１０ＭＰａ程度として行えばよい。 In this step, the catalyst layer forming powder is sprayed and attached to the surface of the electrolyte membrane, and then thermocompression bonded. What is necessary is just to determine the conditions of thermocompression bonding suitably according to the kind etc. of resin to be used. For example, the temperature may be about 80 to 130 ° C. and the pressure may be about 0.5 to 10 MPa.
また、本工程の後、形成された触媒層の表面に、例えば、拡散層となるカーボンクロス等を接合して酸素極とすればよい。 Further, after this step, for example, a carbon cloth or the like serving as a diffusion layer may be joined to the surface of the formed catalyst layer to form an oxygen electrode.
〈固体高分子型燃料電池〉
本発明の固体高分子型燃料電池は、上記本発明の酸素極と、水素を含む燃料ガスが供給される燃料極と、該酸素極と該燃料極との間に挟装された電解質膜と、を備える。本発明の固体高分子型燃料電池は、酸素極を除いて、既に公知の構成に従えばよい。すなわち、電解質膜の一方の表面に本発明の酸素極を形成し、他方の表面に燃料極を形成して、電解質膜電極接合体（以下、適宜「ＭＥＡ」と称す。）を作製する。ここで、燃料極は、例えば以下のようにして形成すればよい。まず、燃料極触媒と電解質の樹脂とを、水やアルコール等の溶媒に分散させて触媒インクを調製する。次いで、調製した触媒インクを所定の基材の表面に塗布、乾燥して、基材表面に燃料極の触媒層を形成する。そして、形成された触媒層を電解質膜の表面に接触させて、基材と電解質膜とを熱圧着する。熱圧着後、基材のみを剥離する。その後、酸素極と同様、形成された触媒層の表面に、拡散層となるカーボンクロス等を接合する。
<Solid polymer fuel cell>
The polymer electrolyte fuel cell according to the present invention includes the oxygen electrode according to the present invention, a fuel electrode to which a fuel gas containing hydrogen is supplied, and an electrolyte membrane sandwiched between the oxygen electrode and the fuel electrode. . The polymer electrolyte fuel cell of the present invention may follow a known configuration except for the oxygen electrode. That is, the oxygen electrode of the present invention is formed on one surface of the electrolyte membrane, and the fuel electrode is formed on the other surface to produce an electrolyte membrane electrode assembly (hereinafter referred to as “MEA” as appropriate). Here, the fuel electrode may be formed as follows, for example. First, a catalyst ink is prepared by dispersing a fuel electrode catalyst and an electrolyte resin in a solvent such as water or alcohol. Next, the prepared catalyst ink is applied to the surface of a predetermined substrate and dried to form a fuel electrode catalyst layer on the substrate surface. And the formed catalyst layer is made to contact the surface of an electrolyte membrane, and a base material and an electrolyte membrane are thermocompression-bonded. After thermocompression bonding, only the substrate is peeled off. Thereafter, similarly to the oxygen electrode, carbon cloth or the like serving as a diffusion layer is bonded to the surface of the formed catalyst layer.
このようにして作製されたＭＥＡを、セパレータを介して複数個積層させて本発明の固体高分子型燃料電池を構成すればよい。セパレータとしては、集電性能が高く、酸化水蒸気雰囲気下でも比較的安定な焼成カーボン、成形カーボンや、ステンレス材料の表面に貴金属や炭素材料を被覆したもの等を用いればよい。 A plurality of MEAs produced in this way may be stacked via a separator to constitute the polymer electrolyte fuel cell of the present invention. As the separator, a fired carbon, molded carbon, or a stainless material whose surface is coated with a noble metal or a carbon material, which has high current collecting performance and is relatively stable even in an oxidizing water vapor atmosphere, may be used.
上記実施形態に基づいて、本発明の酸素極を備えた固体高分子型燃料電池を作製し、電池反応を行うことにより、その水管理性を評価した。以下、順に説明する。 Based on the said embodiment, the polymer electrolyte fuel cell provided with the oxygen electrode of this invention was produced, and the water manageability was evaluated by performing a cell reaction. Hereinafter, it demonstrates in order.
〈固体高分子型燃料電池の作製〉
（１）実施例１のＭＥＡ
カチオン交換樹脂としてナフィオン（登録商標、デュポン社製）を、アニオン交換樹脂としてＰＶＢＴＭＡを用い、酸素極の触媒層を形成した。まず、酸素極触媒をアニオン交換樹脂で被覆したアニオン交換樹脂被覆触媒の粉末を製造した。ＰＶＢＴＭＡの８．９ｗｔ％水溶液４５ｇと、カーボンに担持された白金触媒（白金担持率６０ｗｔ％、以下「Ｐｔ／Ｃ触媒」と表す。）１０ｇと、蒸留水１００ｇとを混合し、超音波分散した。そして、この分散液をスプレードライした後、真空乾燥してアニオン交換樹脂被覆触媒粉末を得た。スプレードライは室温下、空気中で行い、真空乾燥は６０℃下で行った。
<Production of polymer electrolyte fuel cell>
(1) MEA of Example 1
Using Nafion (registered trademark, manufactured by DuPont) as the cation exchange resin and PVBTMA as the anion exchange resin, an oxygen electrode catalyst layer was formed. First, an anion exchange resin-coated catalyst powder in which an oxygen electrode catalyst was coated with an anion exchange resin was produced. 45 g of an 8.9 wt% PVBTMA aqueous solution, 10 g of a platinum catalyst supported on carbon (
次に、カチオン交換樹脂の粉末を製造した。ナフィオン溶液（デュポン社製「ＤＥ１０２０」、ポリマー濃度：約１０ｗｔ％）をスプレードライした後、真空乾燥してカチオン交換樹脂粉末を得た。スプレードライは８０℃下、窒素中で行った。 Next, a cation exchange resin powder was produced. A Nafion solution (“DE1020” manufactured by DuPont, polymer concentration: about 10 wt%) was spray-dried and then vacuum-dried to obtain a cation exchange resin powder. Spray drying was performed at 80 ° C. in nitrogen.
製造したアニオン交換樹脂被覆触媒粉末１．４ｇと、カチオン交換樹脂粉末０．４ｇとを、ミキサーで乾式混合し、触媒層形成用粉末とした。電解質膜にはナフィオン膜（デュポン社製「Ｎ−１１２」）を使用した。ナフィオン膜の一方の表面の３６ｍｍ角の範囲内に、触媒層形成用粉末１９．５ｍｍをふるいでほぼ均一に散布した。ナフィオン膜の表面に付着した単位面積あたりの白金量は、約０．５ｍｇ／ｃｍ2であった。 1.4 g of the produced anion exchange resin-coated catalyst powder and 0.4 g of the cation exchange resin powder were dry-mixed with a mixer to obtain a catalyst layer forming powder. A Nafion membrane (“N-112” manufactured by DuPont) was used as the electrolyte membrane. Within the range of 36 mm square on one surface of the Nafion membrane, 19.5 mm of the catalyst layer forming powder was dispersed almost uniformly. The amount of platinum per unit area attached to the surface of the Nafion film was about 0.5 mg / cm 2 .
一方、Ｐｔ／Ｃ触媒と、ナフィオン溶液と、蒸留水と、イソプロパノールとを混合し、燃料極の触媒インクを調製した。調製した触媒インクを、テフロン（登録商標、デュポン社製）製のシート表面にドクターブレード法により塗布した。その後、室温で真空乾燥して溶媒を除去し、シート表面に燃料極の触媒層を形成した。なお、燃料極の触媒層では、単位面積あたりの白金量を約０．２ｍｇ／ｃｍ2とした。このシートを３６ｍｍ角に切り出した後、燃料極の触媒層が形成された側を上記ナフィオン膜の他方の表面に合わせ、一方の表面に付着した上記触媒層形成用粉末とともに、ホットプレスした。ホットプレスは、１３０℃で２０分間行った。その後、燃料極側のシートのみを剥離し、ナフィオン膜の両側に、酸素極の触媒層と燃料極の触媒層とがそれぞれ形成されたＭＥＡを得た。得られたＭＥＡを実施例１のＭＥＡとした。 On the other hand, a Pt / C catalyst, a Nafion solution, distilled water, and isopropanol were mixed to prepare a fuel electrode catalyst ink. The prepared catalyst ink was applied to the surface of a sheet made of Teflon (registered trademark, manufactured by DuPont) by the doctor blade method. Thereafter, the solvent was removed by vacuum drying at room temperature, and a fuel electrode catalyst layer was formed on the sheet surface. In the catalyst layer of the fuel electrode, the amount of platinum per unit area was about 0.2 mg / cm 2 . After cutting this sheet into 36 mm squares, the side on which the catalyst layer of the fuel electrode was formed was aligned with the other surface of the Nafion membrane, and hot pressed together with the catalyst layer forming powder adhering to one surface. Hot pressing was performed at 130 ° C. for 20 minutes. Thereafter, only the fuel electrode side sheet was peeled off to obtain an MEA in which an oxygen electrode catalyst layer and a fuel electrode catalyst layer were formed on both sides of the Nafion membrane, respectively. The obtained MEA was designated as MEA of Example 1.
（２）実施例２のＭＥＡ
触媒層形成用粉末の製造方法を以下のように変更した以外は、上記実施例１のＭＥＡと同様にＭＥＡを作製した。すなわち、まず、アニオン交換樹脂であるＰＶＢＴＭＡの８．９ｗｔ％水溶液４．５ｇ中に、実施例１のＭＥＡの作製に使用したカチオン交換樹脂粉末０．４ｇと、Ｐｔ／Ｃ触媒１．０ｇと、蒸留水１．０ｇとを加え、超音波分散した。次いで、この分散液をスプレードライした後、真空乾燥して触媒層形成用粉末を得た。スプレードライは室温下、空気中で行い、真空乾燥は６０℃下で行った。得られたＭＥＡを実施例２のＭＥＡとした。
(2) MEA of Example 2
An MEA was produced in the same manner as the MEA of Example 1 except that the method for producing the catalyst layer forming powder was changed as follows. That is, first, in 4.5 g of an 8.9 wt% aqueous solution of PVBTMA that is an anion exchange resin, 0.4 g of the cation exchange resin powder used in the production of the MEA of Example 1, and 1.0 g of a Pt / C catalyst, Distilled water (1.0 g) was added and ultrasonically dispersed. Next, the dispersion was spray-dried and then vacuum-dried to obtain a catalyst layer forming powder. Spray drying was performed in air at room temperature, and vacuum drying was performed at 60 ° C. The obtained MEA was designated as MEA of Example 2.
（３）比較例１のＭＥＡ
酸素極の触媒層を、アニオン交換樹脂を含まない従来の触媒層とした以外は、上記実施例１のＭＥＡと同様にＭＥＡを作製した。すなわち、燃料極の触媒層と同様に、Ｐｔ／Ｃ触媒、ナフィオン溶液等から酸素極の触媒インクを調製し、その触媒インクを用いて酸素極の触媒層を形成した。なお、酸素極の触媒層では、単位面積あたりの白金量を約０．５ｍｇ／ｃｍ2とした。また、酸素極触媒と樹脂との重量比は、実施例１のＭＥＡと同じとした。得られたＭＥＡを比較例１のＭＥＡとした。
(3) MEA of Comparative Example 1
An MEA was produced in the same manner as the MEA of Example 1 except that the oxygen electrode catalyst layer was a conventional catalyst layer containing no anion exchange resin. That is, similarly to the fuel electrode catalyst layer, an oxygen electrode catalyst ink was prepared from a Pt / C catalyst, a Nafion solution, or the like, and an oxygen electrode catalyst layer was formed using the catalyst ink. In the catalyst layer of the oxygen electrode, the amount of platinum per unit area was about 0.5 mg / cm 2 . The weight ratio of the oxygen electrode catalyst to the resin was the same as that of the MEA of Example 1. The obtained MEA was used as the MEA of Comparative Example 1.
（４）比較例２のＭＥＡ
触媒層形成用粉末の製造方法を以下のように変更した以外は、上記実施例１のＭＥＡと同様にＭＥＡを作製した。すなわち、ナフィオン溶液４０ｇと、ＰＶＢＴＭＡの８．９ｗｔ％水溶液４５ｇと、Ｐｔ／Ｃ触媒１０ｇと、蒸留水５０ｇとを混合し、超音波分散した。そして、この分散液をスプレードライした後、真空乾燥して触媒層形成用粉末を得た。スプレードライは室温下、空気中で行い、真空乾燥は６０℃下で行った。得られたＭＥＡを比較例２のＭＥＡとした。
(4) MEA of Comparative Example 2
An MEA was produced in the same manner as the MEA of Example 1 except that the method for producing the catalyst layer forming powder was changed as follows. That is, 40 g of Nafion solution, 45 g of an 8.9 wt% PVBTMA aqueous solution, 10 g of a Pt / C catalyst, and 50 g of distilled water were mixed and ultrasonically dispersed. The dispersion was spray-dried and then vacuum-dried to obtain a catalyst layer forming powder. Spray drying was performed in air at room temperature, and vacuum drying was performed at 60 ° C. The obtained MEA was used as the MEA of Comparative Example 2.
〈水管理性の評価〉
作製した各々のＭＥＡを、試験用の燃料電池評価セルに組み付けた。すなわち、ＭＥＡの両側に、ガス流路が形成されたカーボン製のセパレータを配置して、それをＳＵＳ製の支持体で保持した。そして、酸素極に加湿した空気を、燃料極に加湿した水素をそれぞれ供給し、電池を作動させた。空気は、加湿温度を４０〜８０℃まで変化させ、１Ｌ／ｍｉｎの流量で供給し、水素は、加湿温度を８０℃、０．５Ｌ／ｍｉｎの流量で供給した。両極の背圧は約０．１ＭＰａ、セル温度は８０℃とした。
<Evaluation of water management>
Each of the produced MEAs was assembled into a test fuel cell evaluation cell. That is, carbon separators with gas flow paths formed on both sides of the MEA were placed and held by a SUS support. Then, the humidified air was supplied to the oxygen electrode and the humidified hydrogen was supplied to the fuel electrode to operate the battery. Air was supplied at a flow rate of 1 L / min while changing the humidification temperature from 40 to 80 ° C, and hydrogen was supplied at a flow rate of 1 L / min at a flow rate of 80 L and 0.5 L / min. The back pressure of both electrodes was about 0.1 MPa, and the cell temperature was 80 ° C.
図１に、酸素極の加湿温度と電池出力との関係を示す。図１に示すグラフの縦軸（最大出力比）は、各セルごとに測定された最大出力に対する出力比である。図１に示すように、実施例１、２のＭＥＡを用いたセルでは、広い加湿温度範囲で高い出力が得られた。特に、加湿温度が低い場合、つまり、酸素極に乾いた空気を供給した場合ほど、比較例１の従来のＭＥＡを用いたセルとの出力差が大きかった。これは、実施例１、２のＭＥＡを用いたセルでは、電池反応が活性化されたことに加え、酸素極で生成した水が、速やかに排出されたためと考えられる。このように、本発明の酸素極を備える固体高分子型燃料電池は、水管理性に優れることがわかる。なお、比較例２のＭＥＡを用いたセルでは、有効な発電を確認することができなかった。この原因は、酸素極の触媒層を形成するための触媒層形成用粉末の製造方法にある。つまり、比較例２のＭＥＡでは、触媒層形成用粉末の製造過程において、カチオン交換樹脂溶液（ナフィオン溶液）とアニオン交換樹脂水溶液（ＰＶＢＴＭＡ水溶液）とを混合した。これにより、両樹脂が反応し、酸素極触媒を被覆する樹脂がイオン伝導性を失ったため、電池反応が有効に行われなかったと考えられる。 FIG. 1 shows the relationship between the humidification temperature of the oxygen electrode and the battery output. The vertical axis (maximum output ratio) of the graph shown in FIG. 1 is the output ratio with respect to the maximum output measured for each cell. As shown in FIG. 1, in the cells using the MEAs of Examples 1 and 2, a high output was obtained in a wide humidification temperature range. In particular, when the humidification temperature is low, that is, when dry air is supplied to the oxygen electrode, the output difference from the cell using the conventional MEA of Comparative Example 1 is larger. This is presumably because, in the cells using the MEAs of Examples 1 and 2, the battery reaction was activated and the water generated at the oxygen electrode was quickly discharged. Thus, it turns out that the polymer electrolyte fuel cell provided with the oxygen electrode of the present invention is excellent in water manageability. In the cell using the MEA of Comparative Example 2, effective power generation could not be confirmed. This is due to the method for producing the catalyst layer forming powder for forming the oxygen electrode catalyst layer. That is, in the MEA of Comparative Example 2, a cation exchange resin solution (Nafion solution) and an anion exchange resin aqueous solution (PVBTMA aqueous solution) were mixed during the production process of the catalyst layer forming powder. Thus, it is considered that the battery reaction was not effectively performed because both resins reacted and the resin covering the oxygen electrode catalyst lost ionic conductivity.
Claims (8)
該アニオン交換樹脂は、該酸素極触媒を被覆するよう配置され、
該カチオン交換樹脂は、該アニオン交換樹脂と接するよう配置された触媒層を持つ固体高分子型燃料電池用酸素極。 Including an oxygen electrode catalyst, an anion exchange resin, and a cation exchange resin,
The anion exchange resin is disposed to cover the oxygen electrode catalyst;
The cation exchange resin is an oxygen electrode for a polymer electrolyte fuel cell having a catalyst layer disposed in contact with the anion exchange resin.
該触媒層形成用粉末を電解質膜の表面に付着させ、熱圧着することにより該電解質膜の表面に触媒層を形成する触媒層形成工程と、
を含む固体高分子型燃料電池用酸素極形成方法。 A catalyst layer forming powder preparation step of preparing a catalyst layer forming powder comprising an anion exchange resin-coated catalyst in which an oxygen electrode catalyst is coated with an anion exchange resin, and a cation exchange resin;
A catalyst layer forming step of forming the catalyst layer on the surface of the electrolyte membrane by attaching the catalyst layer forming powder to the surface of the electrolyte membrane and thermocompression bonding;
A method for forming an oxygen electrode for a polymer electrolyte fuel cell.
前記触媒層形成用粉末は、該アニオン交換樹脂を水に溶解させたアニオン交換樹脂水溶液に、酸素極触媒の粉末と非水溶性カチオン交換樹脂の粉末とを分散させ、乾燥して製造される請求項２に記載の固体高分子型燃料電池用酸素極形成方法。 The anion exchange resin is water soluble;
The catalyst layer forming powder is produced by dispersing an oxygen electrode catalyst powder and a water-insoluble cation exchange resin powder in an anion exchange resin aqueous solution in which the anion exchange resin is dissolved in water, and drying the powder. Item 3. The method for forming an oxygen electrode for a polymer electrolyte fuel cell according to Item 2.
前記触媒層形成用粉末は、該アニオン交換樹脂を水以外の溶媒に溶解させたアニオン交換樹脂溶液に、酸素極触媒の粉末とカチオン交換樹脂の粉末とを分散させ、乾燥して製造される請求項２に記載の固体高分子型燃料電池用酸素極形成方法。 The anion exchange resin is insoluble in water;
The catalyst layer forming powder is produced by dispersing an oxygen electrode catalyst powder and a cation exchange resin powder in an anion exchange resin solution obtained by dissolving the anion exchange resin in a solvent other than water and drying the powder. Item 3. The method for forming an oxygen electrode for a polymer electrolyte fuel cell according to Item 2.
前記触媒層形成用粉末は、酸素極触媒が該アニオン交換樹脂で被覆されたアニオン交換樹脂被覆触媒の粉末を、カチオン交換樹脂を溶媒に溶解させたカチオン交換樹脂溶液に分散させ、乾燥して製造される請求項２に記載の固体高分子型燃料電池用酸素極形成方法。 The anion exchange resin is insoluble in water;
The powder for forming the catalyst layer is produced by dispersing an anion exchange resin-coated catalyst powder in which an oxygen electrode catalyst is coated with the anion exchange resin in a cation exchange resin solution in which a cation exchange resin is dissolved in a solvent and drying the powder. The method for forming an oxygen electrode for a polymer electrolyte fuel cell according to claim 2.
水素を含む燃料ガスが供給される燃料極と、
該酸素極と該燃料極との間に挟装された電解質膜と、
を備える固体高分子型燃料電池。 An oxygen electrode catalyst, an anion exchange resin, and a cation exchange resin, wherein the anion exchange resin is disposed so as to cover the oxygen electrode catalyst, and the cation exchange resin is disposed in contact with the anion exchange resin. An oxygen electrode having a catalyst layer and supplied with an oxidant gas containing oxygen;
A fuel electrode supplied with a fuel gas containing hydrogen;
An electrolyte membrane sandwiched between the oxygen electrode and the fuel electrode;
A polymer electrolyte fuel cell comprising:
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007149503A (en) * | 2005-11-28 | 2007-06-14 | Toyota Central Res & Dev Lab Inc | Membrane-electrode assembly and its manufacturing method |
| JP2011113799A (en) * | 2009-11-26 | 2011-06-09 | Hitachi Ltd | Membrane electrode assembly and fuel cell using the same |
| WO2012046566A1 (en) * | 2010-10-04 | 2012-04-12 | 日産自動車株式会社 | Electrode for fuel cell and membrane electrode assembly |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007149503A (en) * | 2005-11-28 | 2007-06-14 | Toyota Central Res & Dev Lab Inc | Membrane-electrode assembly and its manufacturing method |
| JP2011113799A (en) * | 2009-11-26 | 2011-06-09 | Hitachi Ltd | Membrane electrode assembly and fuel cell using the same |
| WO2012046566A1 (en) * | 2010-10-04 | 2012-04-12 | 日産自動車株式会社 | Electrode for fuel cell and membrane electrode assembly |
| CN103098275A (en) * | 2010-10-04 | 2013-05-08 | 日产自动车株式会社 | Electrode for fuel cell and membrane electrode assembly |
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