JP2006032163A - Power generation element for liquid fuel cell, and liquid fuel cell using it - Google Patents

Power generation element for liquid fuel cell, and liquid fuel cell using it Download PDF

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JP2006032163A
JP2006032163A JP2004210307A JP2004210307A JP2006032163A JP 2006032163 A JP2006032163 A JP 2006032163A JP 2004210307 A JP2004210307 A JP 2004210307A JP 2004210307 A JP2004210307 A JP 2004210307A JP 2006032163 A JP2006032163 A JP 2006032163A
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fuel cell
catalyst layer
liquid fuel
positive electrode
negative electrode
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Shinsuke Shibata
進介 柴田
Hiroshi Kayano
博志 柏野
Yasuo Arishima
康夫 有島
Shoji Nishihara
昭二 西原
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Maxell Holdings Ltd
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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
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation element for a liquid fuel cell in which supply of a fuel or oxygen to the deep part of the catalyst layer, and discharge of carbon dioxide and water from the deep part of the catalyst layer can be maintained smoothly even if the thickness of the catalyst layer is made thicker. <P>SOLUTION: This is the power generating element for the liquid fuel cell which is provided with a positive electrode 2 to reduce oxygen, a negative electrode 1 to oxidize the fuel, and a solid electrolyte film 3 arranged between the positive electrode 2 and the negative electrode 1. The negative electrode 1 and the positive electrode 2 include catalyst layers 1b, 2b of the thickness of 30 μm or more, in which the catalyst layers 1b, 2b contain a catalyst, a fibrous material, and a proton conductive material, and in which the length of the fibrous material is not less than 0.1 times the thickness of the catalyst layers 1b, 2b, and the liquid fuel cell is constituted by using that power generating element for the liquid fuel cell. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、液体燃料電池用発電素子及びそれを用いた液体燃料電池に関する。   The present invention relates to a power generation element for a liquid fuel cell and a liquid fuel cell using the same.

近年、パソコン、携帯電話などのコードレス機器の普及に伴い、その電源である二次電池はますます小型化、高容量化が要望されている。現在、エネルギー密度が高く、小型軽量化が図れる二次電池としてリチウムイオン二次電池が実用化されており、ポータブル電源として需要が増大している。しかし、使用されるコードレス機器の種類によっては、このリチウムイオン二次電池では未だ十分な連続使用時間を保証する程度までには至っていない。   In recent years, with the widespread use of cordless devices such as personal computers and mobile phones, secondary batteries as power sources are increasingly required to be smaller and have higher capacities. Currently, lithium ion secondary batteries have been put into practical use as secondary batteries that have high energy density and can be reduced in size and weight, and the demand for portable power sources is increasing. However, depending on the type of cordless device used, this lithium ion secondary battery has not yet reached a level that guarantees sufficient continuous use time.

このような状況の中で上記要望に応え得る電池として、電解質に固体高分子電解質、正極活物質に空気中の酸素、負極活物質に水素、メタノールなどの燃料を用いる固体高分子型燃料電池が、リチウムイオン二次電池よりも高エネルギー密度が期待できることから注目されている。なかでも、液体燃料であるメタノールを直接電池の反応に利用する直接メタノール型燃料電池は、電池本体に空気を供給するブロアや燃料を供給するポンプなどを用いなくてもよいため、小型化が可能であり、将来のポータブル電源として有望である（例えば、特許文献１参照。）。   Under such circumstances, solid polymer fuel cells that use solid polymer electrolytes as electrolytes, oxygen in the air as positive electrode active materials, and hydrogen, methanol, etc. as negative electrode active materials are available as batteries that can meet the above-mentioned demands. Attention has been paid to the fact that a higher energy density can be expected than lithium ion secondary batteries. In particular, direct methanol fuel cells that use methanol, which is a liquid fuel, for direct cell reactions do not require the use of a blower that supplies air to the cell body or a pump that supplies fuel. Therefore, it is promising as a future portable power supply (see, for example, Patent Document 1).

上記直接メタノール型燃料電池の電極は、正極、負極ともにカーボン粉末上に貴金属粒子を高分散した触媒、プロトン交換樹脂などから構成されている。この燃料電池の放電時において正極では酸素の還元により水が生成し、負極ではメタノールの酸化により二酸化炭素が生成するため、正極、負極ともにガス及び液体の拡散が重要となる。   The electrode of the direct methanol fuel cell is composed of a catalyst in which noble metal particles are highly dispersed on carbon powder, a proton exchange resin, and the like, both in the positive electrode and the negative electrode. During the discharge of the fuel cell, water is generated by reduction of oxygen at the positive electrode and carbon dioxide is generated by oxidation of methanol at the negative electrode. Therefore, diffusion of gas and liquid is important for both the positive electrode and the negative electrode.

一方、車用及び家庭用電源として開発されている固体高分子型燃料電池は、燃料に水素を用いる点が大きく異なる。また、水素を用いる固体高分子型燃料電池の電極厚みは１０〜３０μｍ未満であり、直接メタノール型燃料電池の電極厚みより薄いという違いもある。しかし、それ以外の構成は直接メタノール型燃料電池とほぼ同様である。そのため、水素を用いる固体高分子型燃料電池の技術の一部を直接メタノール型燃料電池にも適応することが可能となる。   On the other hand, polymer electrolyte fuel cells that have been developed as power sources for vehicles and households differ greatly in that hydrogen is used as fuel. Moreover, the electrode thickness of the polymer electrolyte fuel cell using hydrogen is less than 10-30 μm, and there is a difference that it is thinner than the electrode thickness of the direct methanol fuel cell. However, the other configuration is almost the same as that of the direct methanol fuel cell. Therefore, it becomes possible to apply a part of the technology of the solid polymer fuel cell using hydrogen directly to the methanol fuel cell.

従来、水素を用いる固体高分子型燃料電池では、電極のガス拡散性を高め、放電反応をスムーズにすることが検討されてきた。例えば、除去可能な物質を含有させて電極を形成し、その後にその物質を除去することにより、電極中に細孔を形成してガス拡散性を高めることが種々提案されている。具体的には、水溶性短繊維の使用（特許文献２）、酸で溶解する物質の使用（特許文献３）、昇華性物質の使用（特許文献４）、可溶性物質の使用（特許文献５）、可溶性の配向性物質の使用（特許文献６）などにより、電極中に細孔を形成してガス拡散性を高めることが提案されている。   Conventionally, in a polymer electrolyte fuel cell using hydrogen, it has been studied to increase gas diffusibility of an electrode and make a discharge reaction smooth. For example, various proposals have been made to increase the gas diffusibility by forming pores in an electrode by forming an electrode containing a removable substance and then removing the substance. Specifically, use of water-soluble short fibers (Patent Document 2), use of an acid-soluble substance (Patent Document 3), use of a sublimation substance (Patent Document 4), use of a soluble substance (Patent Document 5) It has been proposed to increase the gas diffusibility by forming pores in the electrode by using a soluble orienting substance (Patent Document 6).

また、電極中に空孔形成物質を含有させることにより、電極中に細孔を形成してガス拡散性を高めることも提案されている。例えば、繊維状物質の導入（特許文献７、特許文献８及び特許文献９）、粒径の異なるカーボンの使用（特許文献１０）などにより、電極中に細孔を形成してガス拡散性を高めることが提案されている。   In addition, it has also been proposed to increase the gas diffusibility by forming pores in the electrode by including a pore-forming substance in the electrode. For example, by introducing fibrous substances (Patent Document 7, Patent Document 8 and Patent Document 9), using carbon having different particle diameters (Patent Document 10), etc., pores are formed in the electrode to enhance gas diffusibility. It has been proposed.

以上の提案により、電極厚みが１０〜３０μｍ未満である水素を用いる固体高分子型燃料電池のガス拡散性を良好にし、出力密度を向上することが可能であるとの結果が得られている。
特開２０００−２６８８３６号公報 特開平０８−１８０８７９号公報 特開平０９−１２０８２１号公報 特開平０９−１９９１３８号公報 特開平１０−１８９００５号公報 特開平１０−１８９０１２号公報 特開平１０−２２３２３３号公報 特開２００３−１２３７６９号公報 特開２００３−１５１５６４号公報 特開平１０−２４１７０３号公報 By the above proposal, the result that the gas diffusibility of the polymer electrolyte fuel cell using hydrogen whose electrode thickness is less than 10 to 30 μm can be improved and the output density can be improved is obtained.
JP 2000-268836 A JP 08-180879 A Japanese Patent Laid-Open No. 09-120821 JP 09-199138 A Japanese Patent Laid-Open No. 10-189005 JP-A-10-189012 Japanese Patent Laid-Open No. 10-223233 JP 2003-123769 A JP 2003-151564 A JP-A-10-241703

しかし、直接メタノール型燃料電池は、負極でのメタノールの酸化反応速度が非常に遅いため、それを補うために負極の触媒量を多くし、反応表面積を増加させなければならない。また、固体高分子電解質として、プロトン伝導性固体高分子膜などを用いた場合、メタノールなどの液体燃料が電解質膜を通して正極側に透過してしまうというクロスオーバー現象が生じる。この現象が生じると、正極の触媒上でメタノールと酸素とが直接反応(燃焼)してしまい、本来の電池反応である正極での酸素の還元反応で使用する触媒表面積が減少することになる。これを補うため、負極と同じく、正極の触媒量も多くする必要がある。将来的に、クロスオーバーの問題が解決されれば、正極の触媒量を低減することも可能であるが、現時点では困難である。そこで、現時点で必要な白金触媒量は、正極及び負極ともに、水素を燃料とした場合では０．３〜０．５ｍｇ／ｃｍ2程度が一般的であるのに対し、メタノールを燃料とした場合には５〜１５ｍｇ／ｃｍ2を要するのが現状である。そして、電極層の触媒量を増加させるためには、電極層の厚膜化が不可欠であことから、直接メタノール型燃料電池の電極の厚みは１００μｍ以上になる場合もあり、水素を用いる固体高分子型燃料電池の電極厚みである１０〜３０μｍ未満よりもかなり厚くなる。従って、水素を用いる固体高分子型燃料電池のガス拡散性を高め、放電反応をスムーズにするための前述の提案（特許文献２〜１０）をそのまま直接メタノール型燃料電池に適用しても、電極の厚み方向へのガス拡散性が不十分となる。 However, since the direct methanol fuel cell has a very slow methanol oxidation reaction rate at the negative electrode, the amount of catalyst on the negative electrode must be increased to increase the reaction surface area. Further, when a proton conductive solid polymer membrane or the like is used as the solid polymer electrolyte, a crossover phenomenon occurs in which liquid fuel such as methanol permeates to the positive electrode side through the electrolyte membrane. When this phenomenon occurs, methanol and oxygen directly react (combust) on the positive electrode catalyst, and the surface area of the catalyst used in the reduction reaction of oxygen at the positive electrode, which is the original battery reaction, is reduced. In order to compensate for this, it is necessary to increase the catalyst amount of the positive electrode as well as the negative electrode. If the problem of crossover is solved in the future, it is possible to reduce the amount of catalyst of the positive electrode, but this is difficult at this time. Therefore, the amount of platinum catalyst required at the present time is generally about 0.3 to 0.5 mg / cm 2 when hydrogen is used as the fuel for both the positive electrode and the negative electrode, whereas methanol is used as the fuel. Currently requires 5-15 mg / cm 2 . In order to increase the catalyst amount of the electrode layer, it is indispensable to increase the thickness of the electrode layer. Therefore, the thickness of the electrode of the direct methanol fuel cell may be 100 μm or more. It becomes considerably thicker than 10-30 μm, which is the electrode thickness of the molecular fuel cell. Therefore, even if the above-mentioned proposals (Patent Documents 2 to 10) for enhancing the gas diffusibility of the polymer electrolyte fuel cell using hydrogen and smoothing the discharge reaction are directly applied to the methanol fuel cell, the electrode The gas diffusibility in the thickness direction becomes insufficient.

また、直接メタノール型燃料電池の触媒層において、この厚膜化と同等以上に重要なことは、電池反応を効率良く進行させるため、燃料と酸素、及び反応生成物である二酸化炭素や水が触媒層を通して良好に分布、移動できることである。そのためには、触媒層が、この条件を満足する多孔性構造を備えていることがより必要となる。   In addition, in the catalyst layer of a direct methanol fuel cell, what is more important than this thickening is that fuel and oxygen, and carbon dioxide and water, which are reaction products, are used as a catalyst in order to allow the cell reaction to proceed efficiently. Good distribution and movement through the layers. For that purpose, it is more necessary for the catalyst layer to have a porous structure that satisfies this condition.

そこで、本発明は、触媒層の厚さを厚くしても、触媒層深部までの燃料や酸素の供給、触媒層深部からの二酸化炭素や水の排出を円滑に保ち、電池特性を改善させることができる液体燃料電池用発電素子を提供するものである。   Therefore, even if the thickness of the catalyst layer is increased, the present invention smoothly maintains the supply of fuel and oxygen to the deep part of the catalyst layer and the discharge of carbon dioxide and water from the deep part of the catalyst layer, thereby improving the battery characteristics. It is an object of the present invention to provide a power generation element for a liquid fuel cell.

本発明の液体燃料電池用発電素子は、酸素を還元する正極と、燃料を酸化する負極と、前記正極と前記負極との間に配置された固体電解質とを備えた液体燃料電池用発電素子であって、前記負極は、厚さが３０μｍ以上の触媒層を含み、前記触媒層は、触媒と、繊維状物質と、プロトン伝導性物質とを含み、前記繊維状物質の長さは、前記触媒層の厚さの０．１倍以上であることを特徴とする。   A power generation element for a liquid fuel cell according to the present invention is a power generation element for a liquid fuel cell comprising a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and a solid electrolyte disposed between the positive electrode and the negative electrode. The negative electrode includes a catalyst layer having a thickness of 30 μm or more, and the catalyst layer includes a catalyst, a fibrous material, and a proton conductive material. It is characterized by being at least 0.1 times the thickness of the layer.

また、本発明の液体燃料電池は、上記液体燃料電池用発電素子を備えていることを特徴とする。   Moreover, the liquid fuel cell of the present invention includes the above-described power generation element for a liquid fuel cell.

本発明は、触媒層の厚さを厚くしても触媒層中の物質移動の円滑さを維持でき、高い放電特性を有する液体燃料電池用発電素子を提供することができる。また、本発明の液体燃料電池は、上記液体燃料電池用発電素子を用いることにより、高出力と出力安定性を実現できる。   The present invention can provide a power generation element for a liquid fuel cell that can maintain smoothness of mass transfer in the catalyst layer even when the thickness of the catalyst layer is increased, and has high discharge characteristics. Moreover, the liquid fuel cell of the present invention can realize high output and output stability by using the above-described power generating element for liquid fuel cells.

＜液体燃料電池用発電素子の実施の形態＞
本発明の液体燃料電池用発電素子の一例は、酸素を還元する正極と、燃料を酸化する負極と、上記正極と上記負極との間に配置された固体電解質とを備えた液体燃料電池用発電素子である。また、上記負極は、厚さが３０μｍ以上の負極触媒層を含み、上記負極触媒層は、触媒と、繊維状物質と、プロトン伝導性物質とを含み、上記繊維状物質の長さは、上記負極触媒層の厚さの０．１倍以上である。さらに、上記正極は、厚さが３０μｍ以上の正極触媒層を含み、上記正極触媒層は、触媒と、繊維状物質と、プロトン伝導性物質とを含み、上記繊維状物質の長さは、上記正極触媒層の厚さの０．１倍以上である。 <Embodiment of power generation element for liquid fuel cell>
An example of a power generation element for a liquid fuel cell according to the present invention is a power generation for a liquid fuel cell including a positive electrode for reducing oxygen, a negative electrode for oxidizing fuel, and a solid electrolyte disposed between the positive electrode and the negative electrode. It is an element. The negative electrode includes a negative electrode catalyst layer having a thickness of 30 μm or more, the negative electrode catalyst layer includes a catalyst, a fibrous material, and a proton conductive material, and the length of the fibrous material is as described above. It is at least 0.1 times the thickness of the negative electrode catalyst layer. Further, the positive electrode includes a positive electrode catalyst layer having a thickness of 30 μm or more, the positive electrode catalyst layer includes a catalyst, a fibrous material, and a proton conductive material, and the length of the fibrous material is as described above. It is 0.1 times or more of the thickness of the positive electrode catalyst layer.

上記触媒層に上記繊維状物質を含有させることにより、電極中に最適な細孔を形成でき、これにより、触媒層の厚さを厚くしても、触媒層深部までの燃料や酸素の供給、触媒層深部からの二酸化炭素や水の排出を円滑に保つことができる。   By containing the fibrous substance in the catalyst layer, it is possible to form optimal pores in the electrode, thereby supplying fuel and oxygen to the deep part of the catalyst layer even if the thickness of the catalyst layer is increased, The discharge of carbon dioxide and water from the deep part of the catalyst layer can be maintained smoothly.

上記繊維状物質としては、インジウム−錫複合酸化物（ＩＴＯ）などの金属酸化物からなる針状体、気相成長法で形成したカーボン繊維、又はカーボン、金属、金属酸化物などで被覆した樹脂繊維などを使用できるが、これらに限定はされない。また、樹脂繊維に被覆する金属としては、金、白金などが挙げられ、樹脂繊維に被覆する金属酸化物としては、ＩＴＯ、ＳｉＯ2などが挙げられるが、これらに限定はされない。また、繊維状物質は、導電性を有することがより好ましい。 Examples of the fibrous material include needles made of a metal oxide such as indium-tin composite oxide (ITO), carbon fibers formed by a vapor phase growth method, or a resin coated with carbon, metal, metal oxide, or the like. Although fiber etc. can be used, it is not limited to these. Examples of the metal coated on the resin fiber include gold and platinum, and examples of the metal oxide coated on the resin fiber include ITO and SiO 2 , but are not limited thereto. Moreover, it is more preferable that the fibrous substance has conductivity.

上記触媒層の厚さは、３０μｍ以上５００μｍ以下が好ましく、５０μｍ以上２００μｍ以下がより好ましい。この範囲内であれば、必要な触媒量を確保できるとともに、燃料と酸素、及び反応生成物である二酸化炭素や水が触媒層を通して良好に分布、移動でき、放電特性も低下しないからである。   The thickness of the catalyst layer is preferably 30 μm or more and 500 μm or less, and more preferably 50 μm or more and 200 μm or less. Within this range, the required amount of catalyst can be secured, and the fuel, oxygen, and reaction products such as carbon dioxide and water can be well distributed and moved through the catalyst layer, and the discharge characteristics do not deteriorate.

上記繊維状物質の長さは、上記負極触媒層の厚さの０．１倍以上１倍以下であることが好ましく、０．２倍以上０．５倍以下がより好ましい。上記繊維状物質の長さが、上記負極触媒層の厚さの０．１倍を下回ると、繊維状物質を導入して形成した細孔が電極内部で閉塞孔となり易く、触媒層深部までの燃料や酸素の供給、触媒層深部からの二酸化炭素や水の排出を有効に行うことができなくなる。また、１倍を超えると、触媒層中で繊維状物質がかさ高くなるために、触媒層中に均一に分散することが困難となる場合もある。   The length of the fibrous material is preferably 0.1 times or more and 1 time or less, and more preferably 0.2 times or more and 0.5 times or less the thickness of the negative electrode catalyst layer. If the length of the fibrous material is less than 0.1 times the thickness of the negative electrode catalyst layer, the pores formed by introducing the fibrous material are likely to become clogged pores inside the electrode, It becomes impossible to effectively supply fuel and oxygen and discharge carbon dioxide and water from the deep part of the catalyst layer. On the other hand, if the ratio exceeds 1, the fibrous material becomes bulky in the catalyst layer, and it may be difficult to uniformly disperse in the catalyst layer.

また、上記と同様に、上記繊維状物質の長さは、上記正極触媒層の厚さの０．１倍以上１倍以下が好ましく、０．２倍以上０．５倍以下がより好ましい。   Further, similarly to the above, the length of the fibrous substance is preferably 0.1 to 1 times, more preferably 0.2 to 0.5 times the thickness of the positive electrode catalyst layer.

上記繊維状物質のアスペクト比は、１０以上であることが好ましく、１００以上がより好ましい。この範囲内であれば、電極中に含有された繊維状物質が、種々の物質拡散に寄与する細孔を効率よく形成できるからである。ここで、アスペクト比とは、繊維状物質の繊維長さＬを繊維幅（繊維直径）Ｄで除したＬ／Ｄの値をいう。   The aspect ratio of the fibrous material is preferably 10 or more, and more preferably 100 or more. This is because within this range, the fibrous material contained in the electrode can efficiently form pores that contribute to the diffusion of various materials. Here, the aspect ratio means a value of L / D obtained by dividing the fiber length L of the fibrous substance by the fiber width (fiber diameter) D.

また、上記触媒層中の上記繊維状物質の含有量は、上記触媒１００重量部に対して、０．０１重量部以上１００重量部以下であることが好ましく、１重量部以上１０重量部以下がより好ましい。この範囲内であれば、種々の物質拡散に寄与する細孔を充分形成でき、触媒層の厚さも適度に保持でき、放電性能が低下しないからである。   Further, the content of the fibrous substance in the catalyst layer is preferably 0.01 parts by weight or more and 100 parts by weight or less, and preferably 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the catalyst. More preferred. Within this range, pores that contribute to the diffusion of various substances can be sufficiently formed, the thickness of the catalyst layer can be maintained appropriately, and the discharge performance does not deteriorate.

また、上記繊維状物質の表面には、上記触媒を担持させることが好ましい。これにより、触媒の実効反応面積を向上させることが可能となり、さらに放電性能の向上が図れる。また、必要に応じて繊維状物質に親水化処理又は撥水化処理を行うこともできる。親水化処理方法としては、例えばシランカップリング剤により繊維状物質の表面を処理する方法を用いることができるが、これに限定されるものではない。また、撥水化処理方法としては、例えば繊維状物質の表面をフッ化処理する方法を用いることができるが、これに限定されるものではない。   The catalyst is preferably supported on the surface of the fibrous material. As a result, the effective reaction area of the catalyst can be improved, and the discharge performance can be further improved. Further, the fibrous material can be subjected to a hydrophilic treatment or a water repellency treatment as necessary. As a hydrophilic treatment method, for example, a method of treating the surface of a fibrous substance with a silane coupling agent can be used, but the method is not limited to this. Moreover, as a water-repellent treatment method, for example, a method of fluorinating the surface of the fibrous material can be used, but the method is not limited to this.

上記負極は、メタノールを酸化する機能を有しており、例えば、多孔性の炭素材料からなる拡散層と、触媒を担持した炭素粉末、プロトン伝導性物質及び上記繊維状物質からなる触媒層とを積層して構成される。   The negative electrode has a function of oxidizing methanol, and includes, for example, a diffusion layer made of a porous carbon material, a carbon powder carrying a catalyst, a proton conductive material, and a catalyst layer made of the fibrous material. It is constructed by stacking.

上記多孔性の炭素材料としては、例えば、カーボンクロス、カーボンペーパーなどを使用することができる。   Examples of the porous carbon material that can be used include carbon cloth and carbon paper.

上記触媒としては、例えば、白金微粒子や、鉄、ニッケル、コバルト、錫、ルテニウム又は金などと白金との合金微粒子などが用いられるが、これらに限定されるものではない。また、上記触媒は、金属単体として単独で用いることもできるが、炭素粉末などの担体に触媒微粒子を高担持して用いることもできる。   Examples of the catalyst include platinum fine particles and alloy fine particles of platinum such as iron, nickel, cobalt, tin, ruthenium, or gold, but are not limited thereto. The above catalyst can be used alone as a single metal, but it can also be used by highly supporting fine catalyst particles on a carrier such as carbon powder.

上記触媒の担体である炭素粉末としては、例えばＢＥＴ比表面積が１０〜２０００ｍ2／ｇのカーボンブラックが用いられる。この炭素粉末に上記触媒を例えばコロイド法を用いて担持する。炭素粉末と触媒の重量比は、炭素粉末１００重量部に対し、触媒を５〜４００重量部とすることが好ましい。この範囲内であれば、十分な触媒活性が得られ、また触媒の粒径が大きくなりすぎず、触媒活性が低下しないからである。 As the carbon powder that is the carrier of the catalyst, for example, carbon black having a BET specific surface area of 10 to 2000 m 2 / g is used. The catalyst is supported on the carbon powder by using, for example, a colloid method. The weight ratio of the carbon powder to the catalyst is preferably 5 to 400 parts by weight of the catalyst with respect to 100 parts by weight of the carbon powder. This is because, within this range, sufficient catalytic activity can be obtained, and the catalyst particle size does not become too large and the catalytic activity does not decrease.

プロトン伝導性物質としては、例えば、ポリパーフルオロスルホン酸樹脂、スルホン化ポリエーテルスルホン酸樹脂、スルホン化ポリイミド樹脂などのスルホン酸基を有する樹脂を用いることができるが、これらに限定されるものではない。このようなプロトン伝導性物質の含有量は、触媒担持炭素粉末１００重量部に対し、２〜２００重量部とすることが好ましい。この範囲内であれば、十分なプロトン伝導性が得られ、また電気抵抗が大きくならず、電池性能が低下しないからである。   As the proton conductive material, for example, a resin having a sulfonic acid group such as a polyperfluorosulfonic acid resin, a sulfonated polyether sulfonic acid resin, and a sulfonated polyimide resin can be used. However, the proton conductive material is not limited thereto. Absent. The content of such a proton conductive material is preferably 2 to 200 parts by weight with respect to 100 parts by weight of the catalyst-supporting carbon powder. This is because, within this range, sufficient proton conductivity can be obtained, the electrical resistance does not increase, and the battery performance does not deteriorate.

上記プロトン伝導性物質は、バインダとしても機能するため、必ずしもさらにバインダを添加する必要はないが、上記負極触媒層には、イオン伝導性を持たないフッ素樹脂バインダを添加してもよい。イオン伝導性を持たないフッ素樹脂バインダとしては、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体（ＰＦＡ）、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（ＦＥＰ）、テトラフルオロエチレン−エチレン共重合体（Ｅ／ＴＦＥ）、ポリビニリデンフルオライド（ＰＶＤＦ）、ポリクロロトリフルオロエチレン（ＰＣＴＦＥ）などを用いることができるが、これらに限定されることはない。上記バインダの粒径としては、０．０１〜１００μｍが好ましい。０．０１μｍ未満では、十分な結着性が得られず、１００μｍを超えると、かさ高くなるために触媒中に均一に分散することができないからである。また、上記バインダの添加量としては、触媒担持炭素粉末１００重量部に対し、０．０１〜１００重量部とすることが好ましい。０．０１重量部未満では、十分な結着性が得られず、１００重量部を超えると電気抵抗が大きくなり、電池性能が低下するからである。   Since the proton conductive material also functions as a binder, it is not always necessary to add a binder. However, a fluorine resin binder having no ion conductivity may be added to the negative electrode catalyst layer. Examples of the fluororesin binder having no ion conductivity include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). , Tetrafluoroethylene-ethylene copolymer (E / TFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE) and the like can be used, but are not limited thereto. The particle size of the binder is preferably 0.01 to 100 μm. If it is less than 0.01 μm, sufficient binding properties cannot be obtained, and if it exceeds 100 μm, it becomes bulky and cannot be uniformly dispersed in the catalyst. The amount of the binder added is preferably 0.01 to 100 parts by weight with respect to 100 parts by weight of the catalyst-supporting carbon powder. If the amount is less than 0.01 parts by weight, sufficient binding properties cannot be obtained. If the amount exceeds 100 parts by weight, the electrical resistance increases and the battery performance decreases.

上記正極は、酸素を還元する機能を有しており、例えば、多孔性の炭素材料からなる拡散層と、触媒を担持した炭素粉末、プロトン伝導性物質及び上記繊維状物質からなる触媒層とを積層して構成される。また、負極と同様に正極の触媒層にフッ素樹脂バインダを添加してもよい。これらの正極の材料としては、前述した負極と同様の材料を用いることができる。なお、正極の触媒層にフッ素樹脂バインダを用いない場合には、正極の拡散層に用いる多孔性の炭素材料としては、撥水処理を行ったものを用いるのが好ましい。正極に撥水性を付与するためである。撥水処理としては、多孔性の炭素材料にフッ素樹脂などを塗布することにより行うことができる。   The positive electrode has a function of reducing oxygen, and includes, for example, a diffusion layer made of a porous carbon material, a carbon powder carrying a catalyst, a proton conductive material, and a catalyst layer made of the fibrous material. It is constructed by stacking. Moreover, you may add a fluororesin binder to the catalyst layer of a positive electrode similarly to a negative electrode. As materials for these positive electrodes, the same materials as those for the negative electrodes described above can be used. When no fluorine resin binder is used for the catalyst layer of the positive electrode, it is preferable to use a porous carbon material that has been subjected to water repellent treatment as the porous carbon material used for the positive electrode diffusion layer. This is to impart water repellency to the positive electrode. The water repellent treatment can be performed by applying a fluorocarbon resin or the like to a porous carbon material.

本実施形態では、正極と負極の間に固体電解質兼セパレータとして機能する電解質膜を配置する。電解質膜は、電子伝導性を持たずプロトンを輸送することが可能な材料により構成される。例えば、ポリパーフルオロスルホン酸樹脂膜、具体的には、デュポン社製の“ナフィオン膜”（商品名）、旭硝子社製の“フレミオン膜” （商品名）、旭化成工業社製の“アシプレックス膜” （商品名）などの固体高分子電解質膜により構成することができる。その他では、スルホン化ポリエーテルスルホン酸樹脂膜、スルホン化ポリイミド樹脂膜、硫酸ドープポリベンズイミダゾール膜などの固体高分子電解質膜からも構成することができる。   In this embodiment, an electrolyte membrane that functions as a solid electrolyte / separator is disposed between the positive electrode and the negative electrode. The electrolyte membrane is made of a material that does not have electronic conductivity and can transport protons. For example, polyperfluorosulfonic acid resin membrane, specifically, “Nafion membrane” (trade name) manufactured by DuPont, “Flemion membrane” (trade name) manufactured by Asahi Glass Co., Ltd., “Aciplex membrane” manufactured by Asahi Kasei Kogyo Co., Ltd. It can be constituted by a solid polymer electrolyte membrane such as “trade name”. In addition, it can also comprise solid polymer electrolyte membranes, such as a sulfonated polyether sulfonic acid resin membrane, a sulfonated polyimide resin membrane, and a sulfuric acid doped polybenzimidazole membrane.

次に、以上の負極材料及び正極材料（電極材料）を用いた電極の製造方法の一例について説明する。先ず、前述の電極材料と水と有機溶剤とを均一に分散してスラリーとする。このスラリーの固形分量は、スラリーの全重量１００重量部に対して１〜７０重量部とするのが好ましい。１重量部未満では十分な粘性が得られないため作業性が悪く、７０重量部を超えると粘性が高くなりすぎて作業性が悪くなるからである。これらの電極材料の分散は、例えばボールミル、ホモジナイザー、超音波分散機などを用いて行うことができるが、これらに限定されない。また、上記有機溶剤としては、例えば、メタノール、エタノール、プロパノール、ブタノールなどが使用できる。   Next, an example of the manufacturing method of the electrode using the above negative electrode material and positive electrode material (electrode material) is demonstrated. First, the above electrode material, water, and organic solvent are uniformly dispersed to form a slurry. The solid content of the slurry is preferably 1 to 70 parts by weight with respect to 100 parts by weight of the total weight of the slurry. When the amount is less than 1 part by weight, sufficient viscosity cannot be obtained, so workability is poor, and when it exceeds 70 parts by weight, the viscosity becomes too high and workability is deteriorated. These electrode materials can be dispersed using, for example, a ball mill, a homogenizer, an ultrasonic disperser, or the like, but is not limited thereto. Moreover, as said organic solvent, methanol, ethanol, a propanol, butanol etc. can be used, for example.

その後、上記で得られたスラリーを、多孔性の炭素材料からなる拡散層に塗布して乾燥する。続いて、熱プレスを行うことで、有機樹脂成分が溶融結着し、電極が形成される。熱プレスの温度は、有機樹脂成分の種類によって異なるが、使用する有機樹脂成分のガラス転移点以上、ガラス転移点を２０℃上回る温度以下（有機樹脂成分の分解温度以下）に設定することが好ましい。プレスの圧力は３〜５０ＭＰａが好ましい。３ＭＰａ未満では電極の成形が十分でなく、５０ＭＰａを超えると電極内のポアがつぶれてしまい、電池性能が低下するからである。   Thereafter, the slurry obtained above is applied to a diffusion layer made of a porous carbon material and dried. Subsequently, by performing hot pressing, the organic resin component is melted and bonded to form an electrode. The temperature of the hot press varies depending on the type of the organic resin component, but it is preferably set to a temperature not lower than the glass transition point of the organic resin component to be used and not higher than 20 ° C. (lower than the decomposition temperature of the organic resin component). . The press pressure is preferably 3 to 50 MPa. If the pressure is less than 3 MPa, the electrode is not sufficiently molded. If the pressure exceeds 50 MPa, the pores in the electrode are crushed and the battery performance is deteriorated.

続いて、このようにして作製した正極及び負極で前述の電解質膜を挟持し、熱プレスで圧着して電極・電解質一体化物を作製する。熱プレスの温度は、１００〜１８０℃に設定することが好ましい。プレスの圧力は３〜５０ＭＰａが好ましい。１００℃未満、３ＭＰａ未満では電極・電解質一体化物の形成が十分でなく、１８０℃及び５０ＭＰａを超えると電極内のポアがつぶれてしまい、電池性能が低下するからである。   Subsequently, the above-described electrolyte membrane is sandwiched between the positive electrode and the negative electrode thus prepared, and pressure-bonded by hot pressing to produce an electrode / electrolyte integrated product. The temperature of the hot press is preferably set to 100 to 180 ° C. The press pressure is preferably 3 to 50 MPa. If the temperature is less than 100 ° C. and less than 3 MPa, the electrode / electrolyte integrated product is not sufficiently formed. If the temperature exceeds 180 ° C. and 50 MPa, the pores in the electrode are crushed and the battery performance is deteriorated.

＜液体燃料電池の実施の形態＞
次に、本発明の液体燃料電池の実施の形態を図面に基づき説明する。図１は、本発明の液体燃料電池の各構成部品をそれぞれ結合させる前の一例を示す断面図である。負極１は、多孔性の炭素材料からなる拡散層１ａと、触媒を担持した炭素粉末、プロトン伝導性物質、繊維状物質からなる触媒層１ｂとを積層して構成されている。正極２は、撥水性を付与した多孔性の炭素材料からなる拡散層２ａと、触媒を担持した炭素粉末、プロトン伝導性物質、繊維状物質からなる触媒層２ｂとを積層して構成されている。電解質膜３は、電子伝導性を持たずプロトンを輸送することが可能な固体高分子電解質膜から構成されている。 <Embodiment of liquid fuel cell>
Next, embodiments of the liquid fuel cell of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example before each component of the liquid fuel cell of the present invention is coupled. The negative electrode 1 is configured by laminating a diffusion layer 1a made of a porous carbon material and a catalyst layer 1b made of a carbon powder carrying a catalyst, a proton conductive material, and a fibrous material. The positive electrode 2 is configured by laminating a diffusion layer 2a made of a porous carbon material imparted with water repellency and a catalyst layer 2b made of a carbon powder carrying a catalyst, a proton conductive material, and a fibrous material. . The electrolyte membrane 3 is composed of a solid polymer electrolyte membrane that has no electronic conductivity and can transport protons.

負極１、正極２及び電解質膜３は、積層されて電極・電解質一体化物として構成される。即ち、電極・電解質一体化物は、負極１と、正極２と、負極１と正極２との間に設けられた電解質膜３とから構成される。   The negative electrode 1, the positive electrode 2, and the electrolyte membrane 3 are laminated to form an electrode / electrolyte integrated product. That is, the electrode / electrolyte integrated body is composed of the negative electrode 1, the positive electrode 2, and the electrolyte membrane 3 provided between the negative electrode 1 and the positive electrode 2.

負極１の電解質膜３と反対側には、金属からなる負極集電板４を介して、液体燃料５を貯蔵する燃料タンク６が設けられている。液体燃料５としては、例えば、メタノール水溶液、エタノール水溶液、ジメチルエーテル、水素化ホウ素ナトリウム水溶液、水素化ホウ素カリウム水溶液、水素化ホウ素リチウム水溶液などが用いられる。燃料タンク６は、例えば、ＰＴＦＥ、硬質ポリ塩化ビニル、ポリプロピレン、ポリエチレンなどの樹脂や、ステンレス鋼などの耐食性金属から構成されている。負極集電板４には燃料供給孔７が設けられており、この部分から液体燃料５が負極１へと供給される。   On the opposite side of the negative electrode 1 from the electrolyte membrane 3, a fuel tank 6 for storing liquid fuel 5 is provided via a negative electrode current collector plate 4 made of metal. As the liquid fuel 5, for example, methanol aqueous solution, ethanol aqueous solution, dimethyl ether, sodium borohydride aqueous solution, potassium borohydride aqueous solution, lithium borohydride aqueous solution and the like are used. The fuel tank 6 is made of, for example, a resin such as PTFE, hard polyvinyl chloride, polypropylene, or polyethylene, or a corrosion-resistant metal such as stainless steel. A fuel supply hole 7 is provided in the negative electrode current collector plate 4, and liquid fuel 5 is supplied to the negative electrode 1 from this portion.

正極２の電解質膜３と反対側には、金属からなる正極集電板８が設けられており、正極集電板８と正極２とが接する部分には空気孔９が設けられている。これにより、空気孔９を通して大気中の酸素が正極２と接することになる。   A positive electrode current collector plate 8 made of metal is provided on the opposite side of the positive electrode 2 from the electrolyte membrane 3, and an air hole 9 is provided in a portion where the positive electrode current collector plate 8 and the positive electrode 2 are in contact with each other. Thereby, oxygen in the atmosphere comes into contact with the positive electrode 2 through the air holes 9.

また、負極集電板４及び正極集電板８の端部には、それぞれ負極リード線１０、正極リード線１１が接続されている。さらに、上記電極・電解質一体化物の周囲には、シリコーンゴムなどからなるシール材１２が配置されている。   Further, a negative electrode lead wire 10 and a positive electrode lead wire 11 are connected to the ends of the negative electrode current collector plate 4 and the positive electrode current collector plate 8, respectively. Further, a sealing material 12 made of silicone rubber or the like is disposed around the electrode / electrolyte integrated product.

本実施形態の液体燃料電池を完成するには、上記結合前の各構成部品を電極・電解質一体化物に対して垂直に加圧して固定ればよい。   In order to complete the liquid fuel cell of the present embodiment, it is only necessary to press and fix each of the components before the above-mentioned bonding to the electrode / electrolyte integrated product vertically.

（実施例）
以下、本発明の液体燃料電池を実施例に基づき具体的に説明する。ただし、本発明は以下の実施例に限定されるものではない。 (Example)
Hereinafter, the liquid fuel cell of the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples.

以下のようにして、図１と同様の構造の液体燃料電池を作製した。   A liquid fuel cell having the same structure as that shown in FIG. 1 was produced as follows.

正極触媒層は以下のようにして作製した。先ず、平均粒径２ｎｍの白金微粒子（触媒）を５０重量％担持した田中貴金属工業社製の白金担持カーボン“１０Ｅ５０Ｅ”（商品名）を１０重量部、アルドリッチ（Ａｌｄｒｉｃｈ）社製のプロトン伝導性物質“ナフィオン溶液”（商品名、固形分濃度５重量％）を１２０重量部、住友金属鉱山社製の長さ３０〜１００μｍの針状ＩＴＯをボールミルで粉砕した平均長さ２０μｍ、平均直径１．５μｍの針状ＩＴＯ微粒子（繊維状物質、アスペクト比：１３）を１重量部及びイオン交換水を１０重量部準備した。これらをジェットミルで混合分散し、ＰＦＡ製の離型性シート（厚さ：５０μｍ）上に白金量が１ｍｇ／ｃｍ2になるようにアプリケータを用いて塗布して乾燥した。乾燥後に、離型性シートを剥がし取り、厚さ２９μｍの正極触媒層を得た。 The positive electrode catalyst layer was produced as follows. First, 10 parts by weight of platinum-supported carbon “10E50E” (trade name) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., which supports 50% by weight of platinum fine particles (catalyst) having an average particle diameter of 2 nm, and a proton conductive material manufactured by Aldrich 120 parts by weight of “Nafion solution” (trade name, solid content concentration 5% by weight), needle-like ITO 30 to 100 μm long made by Sumitomo Metal Mining Co., Ltd., crushed with a ball mill, average length 20 μm, average diameter 1.5 μm 1 part by weight of acicular ITO fine particles (fibrous material, aspect ratio: 13) and 10 parts by weight of ion-exchanged water were prepared. These were mixed and dispersed by a jet mill, applied onto a PFA release sheet (thickness: 50 μm) using an applicator so that the amount of platinum was 1 mg / cm 2 , and dried. After drying, the release sheet was peeled off to obtain a positive electrode catalyst layer having a thickness of 29 μm.

負極触媒層は以下のように作製した。先ず、平均粒径５ｎｍの白金ルテニウム合金（合金重量比１:１）微粒子（触媒）を５４重量％担持した田中貴金属工業社製の白金ルテニウム担持カーボン“６１Ｅ５４”（商品名）を１０重量部、アルドリッチ社製のプロトン伝導性物質“ナフィオン溶液”（商品名、固形分濃度５重量％）を１５０重量部、住友金属鉱山社製の長さ３０〜１００μｍの針状ＩＴＯをボールミルで粉砕した平均長さ２０μｍ、平均直径１．５μｍの針状ＩＴＯ微粒子（繊維状物質、アスペクト比：１３）を１重量部及びイオン交換水を１０重量部準備した。これらをジェットミルで混合分散し、ＰＦＡ製の離型性シート（厚さ：５０μｍ）上に白金−ルテニウム量が１ｍｇ／ｃｍ2になるようにアプリケータを用いて塗布して乾燥した。乾燥後に、離型性シートを剥がし取り、厚さ２６μｍの負極触媒層を得た。 The negative electrode catalyst layer was produced as follows. First, 10 parts by weight of platinum ruthenium-supported carbon “61E54” (trade name) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., which supports 54% by weight of platinum ruthenium alloy (alloy weight ratio 1: 1) fine particles (catalyst) having an average particle diameter of 5 nm, An average length obtained by pulverizing 150 to 100 parts by weight of a proton conductive material “Nafion solution” (trade name, solid content concentration of 5% by weight) manufactured by Aldrich, and a 30 to 100 μm long needle-shaped ITO manufactured by Sumitomo Metal Mining Co., Ltd. with a ball mill. 1 part by weight of acicular ITO fine particles (fibrous substance, aspect ratio: 13) having a thickness of 20 μm and an average diameter of 1.5 μm and 10 parts by weight of ion-exchanged water were prepared. These were mixed and dispersed by a jet mill, applied onto a PFA release sheet (thickness: 50 μm) using an applicator so that the amount of platinum-ruthenium was 1 mg / cm 2 , and dried. After drying, the release sheet was peeled off to obtain a negative electrode catalyst layer having a thickness of 26 μm.

また、拡散層として東レ社製のカーボンペーパー“ＴＧＰ−Ｈ−０９０”（厚さ：２８０μｍ）と、電解質膜としてデュポン社製の固体高分子電解質膜“ナフィオン１１２”（商品名）とを準備した。   In addition, carbon paper “TGP-H-090” (thickness: 280 μm) manufactured by Toray Industries, Inc. as a diffusion layer and a solid polymer electrolyte membrane “Nafion 112” (trade name) manufactured by DuPont as an electrolyte membrane were prepared. .

続いて、図１に示すように、上記固体高分子電解質膜の片面に、上記拡散層１枚及び上記正極触媒層２枚（正極触媒層全体の総厚さ：５８μｍ）を配置し、また、上記固体高分子電解質膜の他面に、上記拡散層１枚及び上記負極触媒層５枚（負極触媒層全体の総厚さ：１３０μｍ）を配置し、この両側から１６０℃、１０ＭＰａの条件で３分間熱プレスを行い、電極・電解質一体化物を作製した。なお、電極面積は正極、負極ともに９ｃｍ2とした。 Subsequently, as shown in FIG. 1, one diffusion layer and two positive electrode catalyst layers (total thickness of the whole positive electrode catalyst layer: 58 μm) are arranged on one side of the solid polymer electrolyte membrane, One diffusion layer and five negative electrode catalyst layers (total thickness of the whole negative electrode catalyst layer: 130 μm) are disposed on the other surface of the solid polymer electrolyte membrane, and 3 ° C. under the conditions of 160 ° C. and 10 MPa from both sides. An electrode / electrolyte integrated product was produced by hot pressing for 5 minutes. The electrode area was 9 cm 2 for both the positive electrode and the negative electrode.

また、正極集電板は厚さ１０μｍの金製のシートから構成した。液体燃料としては、１５重量％のメタノール水溶液を用いた。負極集電板は正極集電板と同様に構成した。   The positive electrode current collector plate was composed of a gold sheet having a thickness of 10 μm. As the liquid fuel, a 15 wt% aqueous methanol solution was used. The negative electrode current collector plate was configured in the same manner as the positive electrode current collector plate.

（比較例１）
繊維状物質である上記針状ＩＴＯ微粒子を用いず、正極触媒層１枚の厚さを２８μｍ、負極触媒層１枚の厚さを２５μｍとし、正極触媒層全体として正極触媒層１枚（総厚さ：２８μｍ）、負極触媒層全体として負極触媒層１枚（総厚さ：２５μｍ）を用いた以外は、実施例１と同様にして液体燃料電池を作製した。 (Comparative Example 1)
Without using the above-mentioned acicular ITO fine particles which are fibrous materials, the thickness of one positive electrode catalyst layer is 28 μm, the thickness of one negative electrode catalyst layer is 25 μm, and one positive electrode catalyst layer (total thickness) as the whole positive electrode catalyst layer A liquid fuel cell was produced in the same manner as in Example 1, except that one negative electrode catalyst layer (total thickness: 25 μm) was used as the whole negative electrode catalyst layer.

（比較例２）
繊維状物質である上記針状ＩＴＯ微粒子を用いず、正極触媒層１枚の厚さを２８μｍ、負極触媒層１枚の厚さを２５μｍとし、正極触媒層全体として正極触媒層２枚（総厚さ：５６μｍ）、負極触媒層全体として負極触媒層５枚（総厚さ：１２５μｍ）を用いた以外は、実施例１と同様にして液体燃料電池を作製した。 (Comparative Example 2)
Without using the above-mentioned acicular ITO fine particles, which are fibrous materials, the thickness of one positive electrode catalyst layer is 28 μm, the thickness of one negative electrode catalyst layer is 25 μm, and the positive electrode catalyst layer as a whole has two positive electrode catalyst layers (total thickness) A liquid fuel cell was produced in the same manner as in Example 1 except that five negative electrode catalyst layers (total thickness: 125 μm) were used as the whole negative electrode catalyst layer.

（比較例３）
正極触媒層全体として正極触媒層１枚（総厚さ：２９μｍ）、負極触媒層全体として負極触媒層１枚（総厚さ：２６μｍ）を用いた以外は、実施例１と同様にして液体燃料電池を作製した。 (Comparative Example 3)
A liquid fuel was prepared in the same manner as in Example 1, except that one positive electrode catalyst layer (total thickness: 29 μm) was used as the whole positive electrode catalyst layer and one negative electrode catalyst layer (total thickness: 26 μm) was used as the whole negative electrode catalyst layer. A battery was produced.

（比較例４）
正極触媒層及び負極触媒層の上記針状ＩＴＯ微粒子の平均長さを２μｍ（アスペクト比：１．５）とした以外は、実施例１と同様にして液体燃料電池を作製した。 (Comparative Example 4)
A liquid fuel cell was produced in the same manner as in Example 1 except that the average length of the acicular ITO fine particles in the positive electrode catalyst layer and the negative electrode catalyst layer was 2 μm (aspect ratio: 1.5).

（比較例５）
上記針状ＩＴＯ微粒子に代えて、粒径１０〜３０μｍの球状ＩＴＯ微粒子を用い、正極触媒層１枚の厚さを３０μｍ、負極触媒層１枚の厚さを２７μｍとし、正極触媒層全体として正極触媒層２枚（総厚さ：６０μｍ）、負極触媒層全体として負極触媒層５枚（総厚さ：１３５μｍ）を用いた以外は、実施例１と同様にして液体燃料電池を作製した。 (Comparative Example 5)
Instead of the acicular ITO fine particles, spherical ITO fine particles having a particle diameter of 10 to 30 μm are used, the thickness of one positive electrode catalyst layer is 30 μm, the thickness of one negative electrode catalyst layer is 27 μm, and the positive electrode catalyst layer as a whole is a positive electrode. A liquid fuel cell was produced in the same manner as in Example 1 except that two catalyst layers (total thickness: 60 μm) and five negative electrode catalyst layers (total thickness: 135 μm) were used as the whole negative electrode catalyst layer.

次に、実施例１及び比較例１〜５の液体燃料電池に対して、９００ｍＡ（１００ｍＡ／ｃｍ2）を印加し、５分後の出力密度を測定した。その結果を表１に示す。また、表１では、繊維状物質の平均長さの正極触媒層厚さに対する比率を正極比率、繊維状物質の平均長さの負極触媒層厚さに対する比率を負極比率として表した。 Next, 900 mA (100 mA / cm 2 ) was applied to the liquid fuel cells of Example 1 and Comparative Examples 1 to 5, and the output density after 5 minutes was measured. The results are shown in Table 1. In Table 1, the ratio of the average length of the fibrous material to the thickness of the positive electrode catalyst layer is represented as the positive electrode ratio, and the ratio of the average length of the fibrous material to the thickness of the negative electrode catalyst layer is represented as the negative electrode ratio.

Figure 2006032163
Figure 2006032163

表１から、本発明に係る実施例１は、比較例１〜５に比べて出力密度がかなり向上していることが分かる。これに対して、触媒層に繊維状物質を含まない比較例１及び比較例２は、触媒層の厚さにかかわらず出力密度は低下した。一方、比較例３は、触媒層に繊維状物質を含むが、触媒層厚さが３０μｍ未満であるため、繊維状物質含有の効果が現れず、出力密度は向上しなかった。また、比較例４も、触媒層に繊維状物質を含むが、正極比率及び負極比率が０．１倍を下回るため、繊維状物質含有の効果が現れず、出力密度は向上しなかった。さらに、比較例５は、触媒層に球状物質を含有させたが、出力密度は向上しなかった。   From Table 1, it can be seen that the output density of Example 1 according to the present invention is significantly improved as compared with Comparative Examples 1-5. On the other hand, in Comparative Examples 1 and 2 in which the catalyst layer did not contain a fibrous substance, the output density decreased regardless of the thickness of the catalyst layer. On the other hand, in Comparative Example 3, the fibrous material was included in the catalyst layer, but since the catalyst layer thickness was less than 30 μm, the effect of containing the fibrous material did not appear and the output density was not improved. Moreover, although the comparative example 4 also contains a fibrous substance in a catalyst layer, since the positive electrode ratio and the negative electrode ratio are less than 0.1 times, the effect of containing a fibrous substance did not appear, and the output density did not improve. Furthermore, although the comparative example 5 made the catalyst layer contain a spherical substance, the power density was not improved.

以上説明したように本発明は、触媒層の厚さを厚くしても、触媒層深部までの燃料や酸素の供給、触媒層深部からの二酸化炭素や水の排出を円滑に保ち、電池特性を改善させることができる液体燃料電池用発電素子を提供するができる。また、本発明の液体燃料電池用発電素子を用いた液体燃料電池は、パソコン、携帯電話などのコードレス機器の電源の小型化、高容量化を実現できる。   As described above, even if the thickness of the catalyst layer is increased, the present invention smoothly maintains the supply of fuel and oxygen to the deep part of the catalyst layer, the discharge of carbon dioxide and water from the deep part of the catalyst layer, and the battery characteristics. A power generation element for a liquid fuel cell that can be improved can be provided. In addition, a liquid fuel cell using the power generation element for a liquid fuel cell according to the present invention can realize a reduction in size and an increase in capacity of a power source of a cordless device such as a personal computer or a mobile phone.

本発明の液体燃料電池の各構成部品をそれぞれ結合させる前の一例を示す断面図である。It is sectional drawing which shows an example before combining each component of the liquid fuel cell of this invention.

符号の説明Explanation of symbols

１ 負極
１ａ 拡散層
１ｂ 触媒層
２ 正極
２ａ 拡散層
２ｂ 触媒層
３ 電解質膜
４ 負極集電板
５ 液体燃料
６ 燃料タンク
７ 燃料供給孔
８ 正極集電板
９ 空気孔
１０ 負極リード線
１１ 正極リード線
１２ シール材 DESCRIPTION OF SYMBOLS 1 Negative electrode 1a Diffusion layer 1b Catalyst layer 2 Positive electrode 2a Diffusion layer 2b Catalyst layer 3 Electrolyte membrane 4 Negative electrode current collector plate 5 Liquid fuel 6 Fuel tank 7 Fuel supply hole 8 Positive electrode current collector plate 9 Air hole 10 Negative electrode lead wire 11 Positive electrode lead wire 12 Sealing material

Claims (6)

酸素を還元する正極と、燃料を酸化する負極と、前記正極と前記負極との間に配置された固体電解質とを備えた液体燃料電池用発電素子であって、
前記負極は、厚さが３０μｍ以上の触媒層を含み、
前記触媒層は、触媒と、繊維状物質と、プロトン伝導性物質とを含み、
前記繊維状物質の長さは、前記触媒層の厚さの０．１倍以上であることを特徴とする液体燃料電池用発電素子。 A power generating element for a liquid fuel cell comprising a positive electrode for reducing oxygen, a negative electrode for oxidizing fuel, and a solid electrolyte disposed between the positive electrode and the negative electrode,
The negative electrode includes a catalyst layer having a thickness of 30 μm or more,
The catalyst layer includes a catalyst, a fibrous material, and a proton conductive material,
The length of the fibrous substance is not less than 0.1 times the thickness of the catalyst layer. 前記正極は、厚さが３０μｍ以上の触媒層を含み、前記触媒層は、触媒と、繊維状物質と、プロトン伝導性物質とを含み、前記繊維状物質の長さは、前記触媒層の厚さの０．１倍以上である請求項１に記載の液体燃料電池用発電素子。   The positive electrode includes a catalyst layer having a thickness of 30 μm or more, the catalyst layer includes a catalyst, a fibrous material, and a proton conductive material, and the length of the fibrous material is the thickness of the catalyst layer. The power generating element for a liquid fuel cell according to claim 1, wherein the power generating element is 0.1 times or more. 前記繊維状物質の長さは、前記触媒層の厚さの０．１倍以上１倍以下である請求項１又は２に記載の液体燃料電池用発電素子。   3. The power generation element for a liquid fuel cell according to claim 1, wherein a length of the fibrous substance is 0.1 to 1 times a thickness of the catalyst layer. 前記触媒層中の前記繊維状物質の含有量は、前記触媒１００重量部に対して、０．０１重量部以上１００重量部以下である請求項１又は２に記載の液体燃料電池用発電素子。   3. The power generation element for a liquid fuel cell according to claim 1, wherein a content of the fibrous substance in the catalyst layer is 0.01 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the catalyst. 前記繊維状物質のアスペクト比は、１０以上である請求項１〜４のいずれかに記載の液体燃料電池用発電素子。   The power generation element for a liquid fuel cell according to any one of claims 1 to 4, wherein the fibrous substance has an aspect ratio of 10 or more. 請求項１〜５のいずれかに記載の液体燃料電池用発電素子を備えていることを特徴とする液体燃料電池。


A liquid fuel cell comprising the power generating element for a liquid fuel cell according to claim 1.


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WO2007142031A1 (en) * 2006-06-09 2007-12-13 Shin-Etsu Chemical Co., Ltd. Electrolyte membrane-electrode assembly for direct methanol fuel cell
WO2010084753A1 (en) * 2009-01-23 2010-07-29 株式会社 東芝 Fuel cell
JP2014531118A (en) * 2011-10-19 2014-11-20 ジョンソン、マッセイ、フュエル、セルズ、リミテッドＪｏｈｎｓｏｎ Ｍａｔｔｈｅｙ Ｆｕｅｌｃｅｌｌｓｌｉｍｉｔｅｄ Gas diffusion substrate
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WO2007142031A1 (en) * 2006-06-09 2007-12-13 Shin-Etsu Chemical Co., Ltd. Electrolyte membrane-electrode assembly for direct methanol fuel cell
JP2007329065A (en) * 2006-06-09 2007-12-20 Shin Etsu Chem Co Ltd Electrolyte membrane/electrode assembly for direct methanol fuel cell
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JP2014531118A (en) * 2011-10-19 2014-11-20 ジョンソン、マッセイ、フュエル、セルズ、リミテッドＪｏｈｎｓｏｎ Ｍａｔｔｈｅｙ Ｆｕｅｌｃｅｌｌｓｌｉｍｉｔｅｄ Gas diffusion substrate
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