JP4872194B2 - Liquid fuel direct fuel cell - Google Patents

Liquid fuel direct fuel cell Download PDF

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JP4872194B2
JP4872194B2 JP2004212620A JP2004212620A JP4872194B2 JP 4872194 B2 JP4872194 B2 JP 4872194B2 JP 2004212620 A JP2004212620 A JP 2004212620A JP 2004212620 A JP2004212620 A JP 2004212620A JP 4872194 B2 JP4872194 B2 JP 4872194B2
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electrode
fuel cell
catalyst
fuel
ion conductor
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JP2006032249A (en
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進一 上坂
健吾 槇田
尚 富田
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Sony Corp
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    • YGENERAL 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
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    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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    • Y02E60/50Fuel cells

Description

本発明は、液体燃料の透過性に優れた電極を有する、高効率の燃料電池に関するものである。   The present invention relates to a high-efficiency fuel cell having an electrode excellent in liquid fuel permeability.

燃料電池は、燃料の持つエネルギー密度の高さから、電気自動車に限らず、ノートパソコンや携帯電話といったモバイル機器の次世代バッテリーとして期待され、多くの研究機関・企業において研究開発が活発になされている。
特に、イオン透過性の電解質膜として高分子固体電解質を用いた、いわゆる高分子固体電解質型の燃料電池は、比較的動作温度が低いことから、電気自動車や、モバイル機器のバッテリーに好適であると考えられている。
Fuel cells are expected to be the next-generation battery for mobile devices such as notebook computers and mobile phones, not only for electric vehicles, due to the high energy density of fuel, but research and development are actively conducted in many research institutions and companies. Yes.
In particular, a so-called solid polymer electrolyte fuel cell using a solid polymer electrolyte as an ion-permeable electrolyte membrane has a relatively low operating temperature, and is therefore suitable for batteries of electric vehicles and mobile devices. It is considered.

上述したような高分子固体電解質型の燃料電池は、一般的に、イオン伝導性を有する電解質膜の両側に、電極が設けられた構成を有している。
また、燃料電池に用いる燃料としては、水素や、メタノールに代表されるアルコール等、様々な化学物質が検討されている。
特にその中でも、システムの小型化、燃料カートリッジの可搬性等の観点から、メタノール等の液体燃料を電極に直接供給する燃料電池が、モバイル機器用燃料電池として最も有望視されている。
The polymer solid electrolyte type fuel cell as described above generally has a configuration in which electrodes are provided on both sides of an ion conductive electrolyte membrane.
In addition, various chemical substances such as hydrogen and alcohols typified by methanol have been studied as fuels used in fuel cells.
In particular, a fuel cell that directly supplies a liquid fuel such as methanol to an electrode is considered most promising as a fuel cell for a mobile device from the viewpoints of downsizing of the system and portability of a fuel cartridge.

燃料電池の一例として、電解質膜を挟んで一対の電極(燃料極と酸化剤極)が形成された構成のものが挙げられるが、燃料極にメタノールと水との混合液を燃料として供給し、酸素ガス、あるいは空気を酸化剤ガスとして供給することで、以下に示す電気化学反応により発電する。
燃料極: CH3OH+H2O→CO2+6H++6e-
酸化剤極:3/2O2+6H++6e-→3H2
電池反応:CH3OH+3/2O2→CO2+2H2
As an example of the fuel cell, there is a configuration in which a pair of electrodes (a fuel electrode and an oxidant electrode) are formed with an electrolyte membrane interposed therebetween, and a mixed liquid of methanol and water is supplied as fuel to the fuel electrode, Electric power is generated by the following electrochemical reaction by supplying oxygen gas or air as oxidant gas.
Fuel electrode: CH 3 OH + H 2 O → CO 2 + 6H + + 6e
Oxidant electrode: 3/2 O 2 + 6H + + 6e → 3H 2 O
Battery reaction: CH 3 OH + 3 / 2O 2 → CO 2 + 2H 2 O

ところで、メタノール等の液体燃料を直接電極に供給する燃料電池、いわゆる液体燃料直接型燃料電池は、空気(酸素)や水素等の気体を燃料に用いた燃料電池に比較して、特性が悪いことが知られている。
これは、メタノール等の液体燃料は、気体に比較して電極内部に浸透しにくいこと、及び、過電圧が大きく、反応抵抗が大きくなることに起因しているものと考えられている。
By the way, a fuel cell that directly supplies liquid fuel such as methanol to an electrode, that is, a so-called liquid fuel direct type fuel cell, has poor characteristics as compared with a fuel cell that uses gas such as air (oxygen) or hydrogen as a fuel. It has been known.
This is thought to be due to the fact that liquid fuel such as methanol is less likely to penetrate into the electrode than gas, and that the overvoltage is large and the reaction resistance is large.

上述したことから、液体燃料直接型の燃料電池においては、今後、モバイル機器のバッテリーとして実用化することを鑑みれば、特に燃料極側の電極構造を改善することが必要となってくる。   From the above, in the liquid fuel direct type fuel cell, it is necessary to improve the electrode structure on the fuel electrode side particularly in view of practical use as a battery for mobile devices in the future.

このような液体燃料直接型の燃料電池を構成する電極の作製方法、及び電極と電解質膜を接合する方法に関しては、従来においても様々な提案がなされており、例えば、カーボンペーパーのような多孔質の導電材上(集電体)に、白金等よりなる貴金属触媒が担時された炭素粉末と、固体イオン伝導体を溶媒に分散させた触媒インクを、バーコーターやスプレー、または印刷により塗布し、その後、乾燥処理を行い、電解質膜にホットプレスする方法が開示されている(例えば、特許文献1参照。)。   Various proposals have been made in the past regarding a method for producing an electrode constituting such a liquid fuel direct type fuel cell and a method for joining an electrode and an electrolyte membrane. For example, a porous material such as carbon paper has been proposed. On the conductive material (current collector), carbon powder coated with a noble metal catalyst such as platinum and catalyst ink in which a solid ion conductor is dispersed in a solvent are applied by bar coater, spray, or printing. Then, a method of performing a drying process and hot pressing the electrolyte membrane is disclosed (for example, refer to Patent Document 1).

また、テフロン(登録商標)製シートに、白金等よりなる貴金属触媒が担時された炭素粉末と固体イオン伝導体を溶媒に分散させた触媒インクを塗布し、乾燥処理を行い、電解質膜にホットプレスし、その後、テフロン(登録商標)シートを剥がす方法についての開示もなされている(例えば、特許文献2参照。)。   Also, a Teflon (registered trademark) sheet is coated with a catalyst ink in which a noble metal catalyst made of platinum or the like and a solid ion conductor dispersed in a solvent is applied, dried, and hot on the electrolyte membrane. A method of pressing and then peeling the Teflon (registered trademark) sheet is also disclosed (for example, refer to Patent Document 2).

上述したいずれの方法も、貴金属触媒が担時された炭素粉末と固体イオン伝導体を溶媒に分散させて作製した触媒インクを、集電体もしくは電解質膜上に塗布し乾燥させて電極を作製するものである。
これらの方法においては、触媒インク中に含有されている溶媒が揮発する際、電極の内部に、連続した微細な空隙が発生し、これによって燃料又は空気(酸素)の通り道ができ、かつ燃料又は空気(酸素)と触媒の接する反応表面積を大きくすることができる点に特徴を有している。
In any of the above methods, a catalyst ink prepared by dispersing a carbon powder loaded with a noble metal catalyst and a solid ion conductor in a solvent is applied onto a current collector or an electrolyte membrane and dried to produce an electrode. Is.
In these methods, when the solvent contained in the catalyst ink volatilizes, continuous fine voids are generated inside the electrode, thereby allowing passage of fuel or air (oxygen), and fuel or It is characterized in that the reaction surface area where air (oxygen) and the catalyst come into contact can be increased.

しかしながら、上述したような従来方法によると、電極内部には極めて微細な空隙のみしか形成されないため、液体燃料直接型の燃料電池に適用する場合には、未だ液体燃料が充分に電極内部に染み込み難いという問題を有している。その結果、触媒を充分に活用することができなくなり、反応抵抗が大きくなり、燃料電池の特性が充分に発揮できないという技術課題を生じていた。   However, according to the conventional method as described above, only very fine voids are formed inside the electrode. Therefore, when applied to a liquid fuel direct type fuel cell, the liquid fuel still does not sufficiently penetrate into the electrode. Has the problem. As a result, the catalyst cannot be fully utilized, the reaction resistance is increased, and a technical problem that the characteristics of the fuel cell cannot be sufficiently exhibited has occurred.

一方において、燃料電池の特性の向上を図るべく触媒量そのものを増加させると、電極自体が厚くなってしまい、これによって、やはり液体燃料が電極内部に染み込みにくくなり、燃料電池の特性劣化を招来してしまうという問題を生じる。   On the other hand, if the amount of catalyst itself is increased in order to improve the characteristics of the fuel cell, the electrode itself becomes thick, which also makes it difficult for liquid fuel to penetrate into the electrode, leading to deterioration of the characteristics of the fuel cell. The problem of end up.

特開2003−308849号公報JP 2003-308849 A 特開2003−282069号公報JP 2003-282069 A

そこで本発明においては、上述した課題に鑑みて、特に、液体燃料を直接供給する液体燃料直接型の燃料電池において、電極の構造についての検討を行い、燃料、又は空気(酸素)の染み込み易さ、及び生成物の排出のし易さについて改善し、燃料、空気(酸素)と触媒の接する表面積を増大させ、反応抵抗の低減化を図り、電池の特性の向上を図ることを目的とした。   Therefore, in the present invention, in view of the above-described problems, in particular, in a liquid fuel direct type fuel cell that directly supplies liquid fuel, the structure of the electrode is studied, and the infiltration of fuel or air (oxygen) is easy. The purpose of the present invention was to improve the ease of discharge of the product, to increase the surface area where the fuel, air (oxygen) and the catalyst are in contact, to reduce the reaction resistance, and to improve the characteristics of the battery.

本発明の燃料電池は、イオン伝導性を有する電解質膜が、一対の電極によって挟持されてなる構成を有するものであり、一対の電極のうち、少なくともいずれか一方において、 径0.001〜0.1μmの小空隙と、径0.1〜100μmの大空隙とを存した構成を有しているものとする。   The fuel cell of the present invention has a structure in which an electrolyte membrane having ion conductivity is sandwiched between a pair of electrodes, and at least one of the pair of electrodes has a diameter of 0.001 to 0.00. It is assumed that the structure has a small gap of 1 μm and a large gap of 0.1 to 100 μm in diameter.

本発明によれば、燃料電池を構成する電極について、径を特定した小空隙と大空隙とを意図的に形成した構成としたことにより、径の大きな空隙が、特に液体燃料を良好に透過させる機能を発揮し、触媒と、燃料又は空気(酸素)との接触表面積を増大化させることができた。これにより、反応抵抗が低減化でき、燃料電池の特性を大幅に改善できた。
また、本発明の燃料電池を適用することにより、バッテリーによるモバイル機器の駆動時間を大幅に増加させることが可能となった。
According to the present invention, since the electrodes constituting the fuel cell are intentionally formed with a small gap and a large gap whose diameters are specified, the gap having a large diameter allows particularly good liquid fuel to permeate. The function was achieved and the contact surface area between the catalyst and fuel or air (oxygen) could be increased. As a result, the reaction resistance can be reduced, and the characteristics of the fuel cell can be greatly improved.
Further, by applying the fuel cell of the present invention, it has become possible to greatly increase the driving time of the mobile device by the battery.

本発明の燃料電池について、以下、図を参照して詳細に説明する。
図1に、本発明の燃料電池の一例の概略構成図を示す。
燃料電池10は、アノード電極(燃料極)12と、カソード電極(空気極)13とが、電解質膜11を介して積層された電極−膜接合体(MEA:Membrane Electrode Assembly)16と、拡散層14と集電体15とにより構成されているものとする。
Hereinafter, the fuel cell of the present invention will be described in detail with reference to the drawings.
In FIG. 1, the schematic block diagram of an example of the fuel cell of this invention is shown.
The fuel cell 10 includes an electrode-membrane assembly (MEA) 16 in which an anode electrode (fuel electrode) 12 and a cathode electrode (air electrode) 13 are stacked via an electrolyte membrane 11, and a diffusion layer. 14 and the current collector 15.

電解質膜11は、イオン伝導性のある固体イオン伝導体からなるものとし、特に限定されるものではないが、好ましくは、使用する燃料に対して難透過性の材料よりなるものとする。例えば、ナフィオン(デュポン社製、登録商標)が好適な例として挙げられる。また、電解質膜11の膜厚は、20μm〜200μm程度とする。膜厚が20μm未満であると燃料のクロスリーク量が増大することがあり、一方、200μmを超えると、イオンの伝導性が悪化し、機能低下を招来するためである。   The electrolyte membrane 11 is made of a solid ion conductor having ion conductivity and is not particularly limited, but is preferably made of a material that is hardly permeable to the fuel to be used. For example, Nafion (manufactured by DuPont, registered trademark) is a suitable example. Moreover, the film thickness of the electrolyte membrane 11 shall be about 20 micrometers-200 micrometers. If the film thickness is less than 20 μm, the amount of cross-leakage of the fuel may increase. On the other hand, if it exceeds 200 μm, the ion conductivity deteriorates and the function is reduced.

拡散層14は、例えば、カーボンペーパー、カーボンクロス等、電気導電性を有し、かつ、液体又は空気(酸素)を透過する材料よりなり、シート状であるものとする。   The diffusion layer 14 is made of a material having electrical conductivity and transmitting liquid or air (oxygen), such as carbon paper or carbon cloth, and has a sheet shape.

集電体15は、電気導電性に優れている材料よりなり、燃料や空気をポンプ等でMEAに供給する場合、それらの通り道である流路が形成されている形状のものや、メッシュ状の形状になっているものが好適である。   The current collector 15 is made of a material having excellent electrical conductivity. When fuel or air is supplied to the MEA with a pump or the like, the current collector 15 has a shape in which a flow path that is a passage of these is formed, or a mesh shape. What is in a shape is suitable.

本発明の燃料電池10は、アノード、カソードの電極構造に特徴を有しているものである。その構造について以下、詳細に説明する。   The fuel cell 10 of the present invention is characterized by an anode / cathode electrode structure. The structure will be described in detail below.

図2に、従来における電極構造の概略断面図を示し、図3に、本発明における電極構造の概略断面図を示す。
図2に示す従来構造の電極100は、例えばカーボンよりなる担持体粒子21に例えばPt等の貴金属よりなる触媒種22が担持された触媒担持体23と、固体イオン伝導体24とを、所定の溶媒に分散させて調製した触媒インクを、所望の成膜箇所、例えば電解質膜11上に塗布し乾燥させて作製されたものである。この従来構造の電極100においては、溶剤を揮発させる際に、個々の触媒担持体23の間に、微細な空隙25が形成される。
なお、担持体粒子21は必ずしも必要ではなく、この場合、触媒22と固体イオン伝導体が混合されることにより形成される固体イオン伝導体付着触媒粉末が、所定の空隙率をもって、ほぼ均一に分散している状態となる。
FIG. 2 shows a schematic sectional view of a conventional electrode structure, and FIG. 3 shows a schematic sectional view of the electrode structure in the present invention.
An electrode 100 having a conventional structure shown in FIG. 2 includes, for example, a catalyst carrier 23 in which a catalyst seed 22 made of a noble metal such as Pt is supported on a carrier particle 21 made of carbon, and a solid ion conductor 24. The catalyst ink prepared by dispersing in a solvent is prepared by applying the ink on a desired film formation location, for example, the electrolyte membrane 11 and drying it. In the electrode 100 having the conventional structure, when the solvent is volatilized, fine voids 25 are formed between the individual catalyst carriers 23.
The support particles 21 are not necessarily required. In this case, the solid ion conductor-attached catalyst powder formed by mixing the catalyst 22 and the solid ion conductor is dispersed almost uniformly with a predetermined porosity. It will be in the state.

図3に示す本発明構造の電極においては、アノード電極12、カソード電極13の双方、又はどちらか一方において、微細な径(0.001〜0.1μm)の小空隙31と、これよりも大きな径(0.1〜100μm)の大空隙32が形成されている構成を有している。
本発明の電極は、例えばカーボンよりなる担持体粒子21にPt等の貴金属よりなる触媒種22が担持された触媒担持体23と、固体イオン伝導体24が混合されて形成された触媒担持体23の集合体である、固体イオン伝導体付着触媒粉末の塊状体30により構成されているものである。
すなわち、微細な触媒担持体23間に、微細な径(0.001〜0.1μm)の小空隙31が形成され、固体イオン伝導体付着触媒粉末の塊状体30間に、これよりも大きな径(0.1〜100μm)の大空隙32が形成されている構成となっている。
また、担持体粒子21は必ずしも必要ではなく、この場合、触媒22と固体イオン伝導体24とが混合されることにより形成される固体イオン伝導体付着触媒粉末が集合した固体イオン伝導体付着触媒粉末の塊状体30によって電極が構成されることとなる。
In the electrode of the structure of the present invention shown in FIG. 3, a small gap 31 having a fine diameter (0.001 to 0.1 μm) and larger than both of the anode electrode 12 and / or the cathode electrode 13. A large void 32 having a diameter (0.1 to 100 μm) is formed.
The electrode of the present invention is a catalyst carrier 23 formed by mixing a catalyst carrier 23 in which a catalyst species 22 made of a noble metal such as Pt is supported on a carrier particle 21 made of carbon, for example, and a solid ion conductor 24. Which is a mass 30 of solid ion conductor-attached catalyst powder.
That is, a small gap 31 having a fine diameter (0.001 to 0.1 μm) is formed between the fine catalyst carriers 23, and a larger diameter is formed between the mass bodies 30 of the solid ion conductor-attached catalyst powder. A large gap 32 (0.1 to 100 μm) is formed.
The carrier particles 21 are not necessarily required. In this case, the solid ion conductor-attached catalyst powder in which the solid ion conductor-attached catalyst powder formed by mixing the catalyst 22 and the solid ion conductor 24 is gathered. An electrode is constituted by the lump 30.

図3に示すような構造の電極を用いると、大空隙32が、燃料又は空気(酸素)の通り道になり、電極内部まで充分に、供給することが可能となる。
また、微細な小空隙31を併せ持つようにしたことによって、触媒と、燃料や空気とが接する反応表面積が大きくなり、反応効率の向上が図られる。
When the electrode having the structure as shown in FIG. 3 is used, the large gap 32 becomes a passage for fuel or air (oxygen) and can be sufficiently supplied to the inside of the electrode.
In addition, since the small small gap 31 is also provided, the reaction surface area where the catalyst, fuel and air are in contact with each other is increased, and the reaction efficiency is improved.

本発明の燃料電池は、アノード電極12に、燃料となるメタノールを供給し、カソード電極13に、例えば、空気を供給することによって、以下の反応がそれぞれの電極で発生し、プロトンは電解質膜11、電子は外部回路を流れることによりバッテリーとして機能する。
アノード電極:CH3OH+H2O→CO2+6H++6e-
カソード電極:3/2O2+6H++6e-→3H2
In the fuel cell of the present invention, methanol as fuel is supplied to the anode electrode 12 and air is supplied to the cathode electrode 13, for example, whereby the following reaction occurs at each electrode, and protons are generated in the electrolyte membrane 11. Electrons function as a battery by flowing through an external circuit.
Anode electrode: CH 3 OH + H 2 O → CO 2 + 6H + + 6e
Cathode electrode: 3/2 O 2 + 6H + + 6e → 3H 2 O

上述したように本発明に係る電極構成を適用すれば、触媒を効率よく利用することが可能となり、反応抵抗を低減化でき、燃料電池の特性の向上が図られる。  As described above, when the electrode configuration according to the present invention is applied, the catalyst can be used efficiently, the reaction resistance can be reduced, and the characteristics of the fuel cell can be improved.

なお、固体イオン伝導体付着触媒粉末の塊状体30の平均粒径については、電極の種類によって適宜変更することが可能であるが、10μm〜300μmであることが望ましい。
この塊状体30の平均粒径が10μm未満であると、本発明において所望とする大空隙32が形成されなくなってしまい、塊状体30の平均粒径が300μmを超えると、この塊状体30の内部に、燃料や空気(酸素)が染み込みにくくなり、電極としての特性が劣化してしまうためである。
Note that the average particle size of the solid body 30 of the solid ion conductor-attached catalyst powder can be appropriately changed depending on the type of electrode, but is preferably 10 μm to 300 μm.
If the average particle size of the lump 30 is less than 10 μm, the desired large void 32 is not formed in the present invention, and if the average particle size of the lump 30 exceeds 300 μm, the inside of the lump 30 In addition, it is difficult for the fuel and air (oxygen) to permeate, and the characteristics as an electrode deteriorate.

また、電極の空隙率は、20〜35%であることが望ましい。これにより、電極内部における優れた電気導電性及びプロトン伝導性を発揮でき、燃料電池の特性の向上が図られることが確かめられた。   The porosity of the electrode is preferably 20 to 35%. As a result, it was confirmed that excellent electrical conductivity and proton conductivity inside the electrode can be exhibited, and the characteristics of the fuel cell can be improved.

なお、電極の空隙率や、上述した小空隙31と大空隙32の存在比率については、一律に限定されるものではなく、アノード電極、カソード電極、使用する燃料等に応じて、適宜好適な数値を設定することができる。   Note that the porosity of the electrode and the abundance ratio between the small gap 31 and the large gap 32 described above are not uniformly limited, and may be appropriately set according to the anode electrode, the cathode electrode, the fuel used, and the like. Can be set.

次に、本発明の燃料電池の電極の作製方法について、図を参照して説明する。
図4に示すように、先ず、触媒担持体23と固体イオン伝導体24とを溶剤を用いて混合調製して触媒インクを作製する。
次に、触媒インクを乾燥させ、固体イオン伝導体付着触媒粉末の凝集体41を作製する。
続いて、所望の粒度分布になるように粉砕処理を行い、固体イオン伝導体付着触媒粉末の塊状体30を作製する。
次に、この塊状体30に圧処理を施し、小空隙31と大空隙32とを存する電極を形成する。
Next, a method for producing the electrode of the fuel cell of the present invention will be described with reference to the drawings.
As shown in FIG. 4, first, the catalyst carrier 23 and the solid ion conductor 24 are mixed and prepared using a solvent to prepare a catalyst ink.
Next, the catalyst ink is dried to produce an aggregate 41 of solid ion conductor-attached catalyst powder.
Subsequently, a pulverization process is performed so as to obtain a desired particle size distribution, and a mass 30 of the solid ion conductor-attached catalyst powder is produced.
Next, subjected to pressure powder process on the masses 30 to form an electrode exists a small gap 31 and large gap 32.

固体イオン伝導体付着触媒粉末の凝集体41は、触媒インクを乾燥させて形成したものであるため微細な小空隙31をもつ。
上記工程においては、これに粉砕処理を行い、塊状体30を作製し、これを圧したことにより、塊状体30間に大空隙32を形成させることができ、最終的に得られる電極において、燃料や空気(酸素)が良好に透過させることができるようになるのである。
また、このような工程によれば、微細な小空隙31と、大空隙32とが混在している構成の電極を容易に作製することができる。
The solid ion conductor-attached catalyst powder agglomerates 41 are formed by drying the catalyst ink, and thus have fine small voids 31.
In the above process, this and milling process, to produce a bulk body 30, by which the pressure powder, it is possible to form a large gap 32 between the masses 30, the finally obtained electrode, Fuel and air (oxygen) can permeate well.
Moreover, according to such a process, the electrode of the structure in which the fine small space | gap 31 and the large space | gap 32 are mixed can be produced easily.

以下、本発明の燃料電池について具体的な例を挙げて説明するが、本発明は、以下に示す実施例に限定されるものではない。   Hereinafter, the fuel cell of the present invention will be described with specific examples, but the present invention is not limited to the following examples.

先ず、アノード電極を構成する触媒担持体23として、PtとRuの比が1:1.5である触媒種を重量パーセント約54%になるようにカーボン粉末に担持させた触媒粉末(田中貴金属株式会社製:TEC61E54)を用意した。
一方、カソード電極を構成する触媒担持体23として、Ptである触媒種を重量パーセント約50%になるようにカーボン粉末に担持させた触媒粉末(田中貴金属株式会社製:TEC10V50E)を用意した。
First, as the catalyst support 23 constituting the anode electrode, a catalyst powder in which a catalyst seed having a Pt / Ru ratio of 1: 1.5 is supported on carbon powder so as to have a weight percent of about 54% (Tanaka Kikinzoku Co., Ltd.) Company-made: TEC61E54) was prepared.
On the other hand, a catalyst powder (manufactured by Tanaka Kikinzoku Co., Ltd .: TEC10V50E) was prepared as a catalyst support 23 constituting the cathode electrode, in which a catalyst seed of Pt was supported on carbon powder so as to have a weight percent of about 50%.

続いて、アノード電極、及びカソード電極のそれぞれにおいて、触媒粉末(触媒担持体)を0.35g、水を1.05g、20wt%の固体イオン伝導体分散溶液(デュポン社製:DE2021)0.75g、及び1−プロパノール2.0gを混合攪拌し、触媒インクを調製した。   Subsequently, in each of the anode electrode and the cathode electrode, 0.35 g of catalyst powder (catalyst support), 1.05 g of water, and 0.75 g of 20 wt% solid ion conductor dispersion solution (manufactured by DuPont: DE2021) And 2.0 g of 1-propanol were mixed and stirred to prepare a catalyst ink.

次に、乾燥処理を行い、触媒インクの溶媒を充分に揮発させ、固体イオン伝導体付着触媒粉末の凝集体41を得た。
その後、乳鉢を用いて凝集体41を粉砕し、所望の平均粒径の固体イオン伝導体付着触媒粉末の塊状体30を得た。
なお、この塊状体30の平均粒径については、10μm〜300μmとする。
Next, a drying process was performed to sufficiently volatilize the solvent of the catalyst ink to obtain an aggregate 41 of the solid ion conductor-attached catalyst powder.
Thereafter, the aggregate 41 was pulverized using a mortar to obtain a mass 30 of the solid ion conductor-attached catalyst powder having a desired average particle diameter.
In addition, about the average particle diameter of this lump 30, it shall be 10 micrometers-300 micrometers.

次に、この塊状体30を、直径が10mmである円筒径金型に30mg入れ、ハンドプレス機により、0.5tの力で圧する。
これにより、空隙率が20〜35%に制御された電極を作製することができる。
Then, the masses 30, placed 30mg in a cylindrical径金type having a diameter of 10 mm, the hand press, to pressure powder with a force of 0.5 t.
Thereby, the electrode by which the porosity was controlled to 20 to 35% can be produced.

次に、上述のようにして作製されたアノード、カソードの両電極を、膜厚183μmである高分子固体電解質膜(デュポン社製:Nafion117)に、120度・0.2kNの条件で15分間ホットプレスし、MEAを作製した。   Next, both the anode and cathode electrodes produced as described above were hot for 15 minutes on a polymer solid electrolyte membrane (DuPont: Nafion 117) having a film thickness of 183 μm under the conditions of 120 ° and 0.2 kN. The MEA was produced by pressing.

このMEAを、厚さ280μmのカーボンペーパー(東レ株式会社製:HGP−H−090)、及びチタンメッシュで挟みこみ、目的とする燃料電池を作製した。
ここで、カーボンペーパーは拡散層14、チタンメッシュは集電体15に相当する。
This MEA was sandwiched between carbon paper having a thickness of 280 μm (manufactured by Toray Industries, Inc .: HGP-H-090) and a titanium mesh to produce a target fuel cell.
Here, the carbon paper corresponds to the diffusion layer 14, and the titanium mesh corresponds to the current collector 15.

比較例として、図2に示したような、触媒担持体23を凝集させた構成の電極を用いてMEAを得、上記実施例と同様に拡散層14、集電体15で挟み込んで燃料電池を作製した。   As a comparative example, an MEA is obtained using an electrode having a configuration in which the catalyst support 23 is aggregated as shown in FIG. 2, and the fuel cell is sandwiched between the diffusion layer 14 and the current collector 15 in the same manner as in the above embodiment. Produced.

次に、上述のようにして作製した燃料電池を発電させる。
アノード電極12側には、重量パーセント5%のメタノール水溶液を注ぎ、カソード電極13側は、大気に解放することによって空気を供給する。
そして、チタンメッシュである集電体15を外部回路に結線し、燃料電池において発電を開始させる。
Next, the fuel cell produced as described above is generated.
A 5% by weight methanol aqueous solution is poured onto the anode electrode 12 side, and air is supplied to the cathode electrode 13 side by releasing it to the atmosphere.
And the collector 15 which is a titanium mesh is connected to an external circuit, and electric power generation is started in a fuel cell.

次に、燃料電池の評価を行った。
燃料電池を電気化学測定装置(ソーラートロン社製:マルチスタット1480)につなぎ、燃料電池の端子電圧が0.8Vになるようにして、電流値が安定するまで測定し、その安定した電流値を読み取る。
この作業を燃料電池の端子電圧が、0.7V、0.6V、0.5V、0.4V、0.3V、0.25Vになる条件で測定し、燃料電池の電流電圧特性曲線を得る。
Next, the fuel cell was evaluated.
Connect the fuel cell to an electrochemical measurement device (Solartron: Multistat 1480) and measure the fuel cell terminal voltage to 0.8V until the current value stabilizes. read.
This operation is measured under the condition that the terminal voltage of the fuel cell is 0.7V, 0.6V, 0.5V, 0.4V, 0.3V, 0.25V, and the current-voltage characteristic curve of the fuel cell is obtained.

本発明に係る燃料電池と、比較例の燃料電池の電流電圧特性曲線を図5に示す。
なお、実線曲線(a)は、実施例の燃料電池の電流電圧特性曲線を示し、破線曲線(b)は、比較例の燃料電池の電流電圧特性曲線を示す。
図5に示すように、本発明に係る燃料電池によれば電気的特性が改善されている。
これは、実施例の燃料電池においては、電極に小空隙と大空隙とを形成せしめたことにより、大空隙に液体燃料を良好に透過させることができ、触媒と、燃料又は空気(酸素)との接触表面積を増大化させることができ、反応抵抗の低減化が図られ、燃料電池の特性の向上が図られたためである。
FIG. 5 shows current-voltage characteristic curves of the fuel cell according to the present invention and the fuel cell of the comparative example.
The solid line curve (a) shows the current-voltage characteristic curve of the fuel cell of the example, and the broken line curve (b) shows the current-voltage characteristic curve of the fuel cell of the comparative example.
As shown in FIG. 5, according to the fuel cell of the present invention, the electrical characteristics are improved.
This is because, in the fuel cell of the example, by forming the small gap and the large gap in the electrode, it is possible to allow the liquid fuel to permeate well through the large gap, and the catalyst and the fuel or air (oxygen). This is because the contact surface area of the fuel cell can be increased, the reaction resistance is reduced, and the characteristics of the fuel cell are improved.

本発明に係る燃料電池の概略断面図を示す。1 is a schematic cross-sectional view of a fuel cell according to the present invention. 従来の燃料電池における電極の概略構成図を示す。The schematic block diagram of the electrode in the conventional fuel cell is shown. 本発明の燃料電池における電極の概略構成図を示す。The schematic block diagram of the electrode in the fuel cell of this invention is shown. 本発明の燃料電池の電極作製工程図を示す。The electrode manufacturing process figure of the fuel cell of this invention is shown. 実施例と比較例の燃料電池の電流電圧特性曲線を示す。The current-voltage characteristic curve of the fuel cell of an Example and a comparative example is shown.

符号の説明Explanation of symbols

10……燃料電池、11……電解質膜、12……アノード電極、13……カソード電極、14……拡散層、15……集電体、21……担持体粒子、22……触媒種、23……触媒担持体、24……固体イオン伝導体、25……空隙、30……固体イオン伝導体付着触媒粉末の塊状体、31……小空隙、32……大空隙、41……固体イオン伝導体付着粉末の凝集体、100……電極





DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Electrolyte membrane, 12 ... Anode electrode, 13 ... Cathode electrode, 14 ... Diffusion layer, 15 ... Current collector, 21 ... Carrier particle, 22 ... Catalyst type, 23 ... Catalyst carrier 24 ... Solid ion conductor 25 ... Cavity 30 ... Collector of catalyst powder with solid ion conductor 31 ... Small void 32 ... Large void 41 ... Solid Aggregates of powder with ion conductor, 100 ... electrode





Claims (1)

イオン伝導性を有する電解質膜が一対の電極によって挟持されてなり、
前記一対の電極のうち少なくとも一方が、
触媒種と固体イオン伝導体とを混合することにより形成される固体イオン伝導体付着触媒粉末の集合体である、平均粒径が10〜300μmの塊状体により構成されており、前記塊状体は、触媒種を担持した触媒担持体と固体イオン伝導体と溶剤とを用いて混合調製した触媒インクを乾燥処理することにより得られる固体イオン伝導体付着触媒粉末の凝集体を粉砕することにより作製され、かつ、径0.001〜0.1μmの小空隙と、径が0.1μmよりも大きく100μm以下である大空隙とが形成されている構成を有し、前記電極の空隙率が20〜35%である液体燃料直接型燃料電池。
An electrolyte membrane having ion conductivity is sandwiched between a pair of electrodes,
At least one of the pair of electrodes is
It is an aggregate of solid ion conductor-attached catalyst powder formed by mixing a catalyst species and a solid ion conductor, and is composed of a mass having an average particle diameter of 10 to 300 μm . It is produced by pulverizing an aggregate of solid ion conductor-attached catalyst powder obtained by drying a catalyst ink mixed and prepared using a catalyst support carrying a catalyst species, a solid ion conductor and a solvent, and possess a small void diameter 0.001~0.1Myuemu, a configuration having a diameter and a large gap which is less larger 100μm than 0.1μm is formed, the porosity of the electrode is 20 to 35% A liquid fuel direct fuel cell.
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