JP5106808B2 - Porous carbon electrode substrate and polymer electrolyte fuel cell using the same - Google Patents

Porous carbon electrode substrate and polymer electrolyte fuel cell using the same Download PDF

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JP5106808B2
JP5106808B2 JP2006208168A JP2006208168A JP5106808B2 JP 5106808 B2 JP5106808 B2 JP 5106808B2 JP 2006208168 A JP2006208168 A JP 2006208168A JP 2006208168 A JP2006208168 A JP 2006208168A JP 5106808 B2 JP5106808 B2 JP 5106808B2
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porous carbon
carbon electrode
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polymer electrolyte
carbon
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JP2008034295A (en
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和宏 隅岡
誠 中村
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Mitsubishi Chemical Corp
Mitsubishi Rayon Co Ltd
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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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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    • Y02E60/50Fuel cells
    • 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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Description

本発明は、固体高分子型燃料電池に好適に用いられる多孔質炭素電極基材とそれを用いた固体高分子型燃料電池等に関するものである。   The present invention relates to a porous carbon electrode substrate suitably used for a polymer electrolyte fuel cell, a polymer electrolyte fuel cell using the same, and the like.

固体高分子型燃料電池はプロトン伝導性の高分子電解質膜を用いることを特徴としており、水素等の燃料ガスと酸素等の酸化ガスを電気化学的に反応させることにより起電力を得る装置である。固体高分子型燃料電池は、自家発電装置や、自動車等の移動体用の発電装置として利用可能である。   A polymer electrolyte fuel cell is characterized by using a proton-conducting polymer electrolyte membrane, and is an apparatus for obtaining an electromotive force by electrochemically reacting a fuel gas such as hydrogen and an oxidizing gas such as oxygen. . The polymer electrolyte fuel cell can be used as a self-power generation device or a power generation device for a moving body such as an automobile.

このような固体高分子型燃料電池は、水素イオン(プロトン)を選択的に伝導する高分子電解質膜を有する。また、貴金属系触媒を担持したカーボン粉末を主成分とする触媒層と多孔質炭素電極基材とを有するガス拡散電極が、触媒層側を内側にして、高分子電解質膜の両面に接合された構造となっている。   Such a polymer electrolyte fuel cell has a polymer electrolyte membrane that selectively conducts hydrogen ions (protons). In addition, a gas diffusion electrode having a catalyst layer mainly composed of carbon powder supporting a noble metal catalyst and a porous carbon electrode substrate was bonded to both surfaces of the polymer electrolyte membrane with the catalyst layer side inside. It has a structure.

このような高分子電解質膜と2枚のガス拡散電極からなる接合体は膜電極接合体(MEA: Membrane Electrode Assembly)と呼ばれている。またMEAの両外側には燃料ガスまたは酸化ガスを供給し、かつ生成ガスおよび過剰ガスを排出することを目的としたガス流路を形成したセパレーターが設置されている。   Such a joined body composed of a polymer electrolyte membrane and two gas diffusion electrodes is called a membrane electrode assembly (MEA). In addition, separators are provided on both outer sides of the MEA so as to supply a fuel gas or an oxidizing gas and to form a gas flow path for the purpose of discharging generated gas and excess gas.

多孔質炭素電極基材は主に次の3つの機能を持つ。第1に多孔質炭素電極基材の外側に配置されたセパレーターに形成されたガス流路より触媒層中の貴金属系触媒に均一に燃料ガスまたは酸化ガスを供給する機能である。第2に触媒層で反応により生成した水を排出する機能である。第3に触媒層での反応に必要な電子または生成される電子をセパレーターへ導電する機能である。   The porous carbon electrode substrate mainly has the following three functions. The first function is to supply the fuel gas or the oxidizing gas uniformly to the noble metal catalyst in the catalyst layer from the gas flow path formed in the separator disposed outside the porous carbon electrode substrate. The second function is to discharge water generated by the reaction in the catalyst layer. The third function is to conduct electrons necessary for the reaction in the catalyst layer or generated electrons to the separator.

したがって、多孔質炭素電極基材には、高い反応ガスおよび酸化ガス透過能、水の排出性、および電子導電性が必要とされる。また、一般的な固体高分子型燃料電池では、多孔質炭素電極基材はMEA作製時に高分子電解質膜の両側に加圧により接合され、これを2枚のセパレーターではさみ締結されるため、多孔質炭素電極基材中の炭素材料が高分子電解質膜へ突き刺さることによる反応ガスのクロスリークや、アノード、カソード両極間での微小ショートなどを引き起こす高分子電解質膜へのダメージを低減することが求められている。   Therefore, the porous carbon electrode base material is required to have high reactive gas and oxidizing gas permeability, water dischargeability, and electronic conductivity. Further, in a general solid polymer fuel cell, the porous carbon electrode base material is bonded to both sides of the polymer electrolyte membrane by pressure when the MEA is manufactured, and is sandwiched between two separators and fastened. It is necessary to reduce damage to the polymer electrolyte membrane that causes cross-leakage of reaction gas due to the carbon material in the porous carbon electrode base material penetrating into the polymer electrolyte membrane, and micro shorts between the anode and cathode. It has been.

反応ガスのクロスリークや、アノード、カソード両極間での微小ショートなどを抑制し、高分子電解質膜へのダメージを低減するための最も一般的な手法として、フッ素樹脂やカーボンブラックなどからなる緻密な層を多孔質炭素電極基材上へ塗布する手法が用いられている。その他の方法として、特許文献1には、合成樹脂からなる多孔質のシート状支持体、並びに導電性カーボン粒子および熱可塑性樹脂からなり、前記シート状支持体を被覆する被覆層からなることを特徴とする燃料電池用ガス拡散層が開示されている。また、特許文献2には、高分子電解質膜と、該高分子電解質膜の表面に設けられた触媒層と、該触媒層の表面に設けられた拡散層と、からなる膜−電極接合体を備えた固体高分子型燃料電池において該触媒層が、繊維状の導電材を有し、かつ該触媒層の厚さ方向の該拡散層の端部の領域の近傍の導電材の含有量が、該高分子電解質膜の端部の近傍の領域の該導電材の含有量より多いことを特徴とする固体高分子型燃料電池が開示されている。
特開2004−152744号公報 特開2005−228601号公報
The most common method for reducing cross-leakage of reactive gases and micro-shorts between the anode and cathode and reducing damage to the polymer electrolyte membrane is a dense material made of fluororesin or carbon black. A technique of applying a layer onto a porous carbon electrode substrate is used. As another method, Patent Document 1 includes a porous sheet-like support made of a synthetic resin, and a coating layer made of conductive carbon particles and a thermoplastic resin that covers the sheet-like support. A gas diffusion layer for a fuel cell is disclosed. Patent Document 2 discloses a membrane-electrode assembly comprising a polymer electrolyte membrane, a catalyst layer provided on the surface of the polymer electrolyte membrane, and a diffusion layer provided on the surface of the catalyst layer. In the polymer electrolyte fuel cell provided, the catalyst layer has a fibrous conductive material, and the content of the conductive material in the vicinity of the end region of the diffusion layer in the thickness direction of the catalyst layer is A solid polymer fuel cell is disclosed in which the content of the conductive material in a region in the vicinity of the end of the polymer electrolyte membrane is greater than that of the polymer electrolyte membrane.
JP 2004-152744 A JP 2005-228601 A

しかし、緻密な層を多孔質炭素電極基材上へ塗布する手法では、緻密な層を形成することにより多孔質炭素電極基材のガス透気度等の物性が変化するという問題があり、この緻密な層の組成や構造、厚みに制限が生じている。特許文献1記載の方法では、反応ガスのクロスリークや、アノード、カソード両極間での微小ショートなどを引き起こす高分子電解質膜のダメージを低減するために、多孔質炭素電極基材を用いず、合成樹脂からなる多孔質シート状に導電性カーボン粒子と熱可塑性樹脂からなる被覆層によりガス拡散電極を形成しているため、十分なガス拡散性と電気導電性を得ることが困難となる。また、特許文献2記載の方法では、触媒層中に高分子電解質膜と接する領域においても少量の繊維状の物質が含まれていることより、反応ガスのクロスリークや、アノード、カソード両極間での微小ショートなどを引き起こす高分子電解質膜のダメージを十分に低減することは困難である。   However, the technique of applying a dense layer on the porous carbon electrode substrate has a problem that the physical properties such as gas permeability of the porous carbon electrode substrate change by forming the dense layer. There are limitations on the composition, structure, and thickness of the dense layer. In the method described in Patent Document 1, a porous carbon electrode substrate is not used in order to reduce damage to the polymer electrolyte membrane that causes cross-leakage of the reaction gas or micro short-circuit between the anode and cathode electrodes. Since the gas diffusion electrode is formed of a coating layer made of conductive carbon particles and a thermoplastic resin in the form of a porous sheet made of resin, it becomes difficult to obtain sufficient gas diffusibility and electrical conductivity. Further, in the method described in Patent Document 2, since a small amount of fibrous material is contained in the catalyst layer in the region in contact with the polymer electrolyte membrane, the reaction gas cross-leakage and between the anode and cathode both electrodes. It is difficult to sufficiently reduce the damage of the polymer electrolyte membrane that causes a micro short circuit.

また、高分子電解質膜へのダメージを低減するためには、高分子電解質膜の機械的強度を上げることや膜厚を厚くすることも可能ではあるが、一般的には機械的強度を上げることや膜厚を厚くすることによりプロトン伝導抵抗が増加し、固体高分子型燃料電池に用いた場合、発電性能が低下するため、固体高分子型燃料電池に用いられる高分子電解質膜の機械的強度や膜厚には制限が生じている。   In order to reduce damage to the polymer electrolyte membrane, it is possible to increase the mechanical strength of the polymer electrolyte membrane or increase the film thickness, but in general increase the mechanical strength. The proton conduction resistance increases by increasing the film thickness, and the power generation performance decreases when used in a polymer electrolyte fuel cell. Therefore, the mechanical strength of the polymer electrolyte membrane used in the polymer electrolyte fuel cell is reduced. There is a limit to film thickness.

本発明はこれら上記従来の技術の課題を解決するもので、固体高分子型燃料電池に用いられる高分子電解質膜へのダメージを低減することができる多孔質炭素電極基材およびその製造方法、また、それを用いた固体高分子型燃料電池を提供することを目的とするものである。   The present invention solves the above-mentioned problems of the prior art, and a porous carbon electrode base material capable of reducing damage to a polymer electrolyte membrane used in a polymer electrolyte fuel cell and a method for producing the same, and An object of the present invention is to provide a polymer electrolyte fuel cell using the same.

上記課題は、以下の本発明により解決できる。   The above problems can be solved by the present invention described below.

本発明の多孔質炭素電極基材の製造方法では、炭素短繊維を炭素により結着した炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分を取り除くための表面処理を行い、その際、前記表面処理は、前記炭素シートの少なくとも一方の表面を吸引仕事率が100〜700Wの吸引装置によって1〜20秒吸引する方法により行う。前記吸引装置は、該吸引装置の吸引口の周囲に固定される刷毛、および該吸引装置の吸引口の内部に取り付けられる回転する刷毛から選ばれる刷毛を備えることができる。また、前記表面処理として、前記炭素シートの少なくとも一方の表面を、吸引仕事率が100〜700Wの吸引装置によって、1〜20秒吸引しつつ、該表面を刷毛で刷くこともできる。さらに、前記炭素短繊維の平均直径は3〜30μmであって、かつ、該炭素短繊維の長さは2mm以上12mm以下であることができる。 In the method for producing a porous carbon electrode base material of the present invention, a surface for removing a fiber portion whose one end is not bound by carbon with respect to at least one surface of a carbon sheet in which short carbon fibers are bound by carbon processing have row, this time, the surface treatment, pre SL suction work rate of at least one surface of the carbon sheet intends more rows to how to suction 20 seconds by a suction device 100~700W. The suction device may include a brush selected from a brush fixed around the suction port of the suction device and a rotating brush attached to the inside of the suction port of the suction device. Further, as the surface treatment, at least one surface of the carbon sheet can be brushed with a brush while being sucked by a suction device having a suction work rate of 100 to 700 W for 1 to 20 seconds. Further, the short carbon fibers may have an average diameter of 3 to 30 μm, and the short carbon fibers may have a length of 2 mm to 12 mm.

本発明の多孔質炭素電極基材は、前記の方法により製造されるものである。このようにして製造される多孔質炭素電極基材は、前記表面処理を行った表面から前記炭素短繊維の平均直径の3倍以内の厚み範囲内に存在する炭素短繊維のうち、両端が炭素により結着している繊維部分が80本数%以上であることが好ましい。   The porous carbon electrode substrate of the present invention is produced by the above method. The porous carbon electrode substrate produced in this way is composed of carbon short fibers existing within a thickness range within 3 times the average diameter of the carbon short fibers from the surface subjected to the surface treatment, and both ends are carbon. It is preferable that 80% or more of the fiber portions are bound by the above.

本発明の膜−電極接合体は、高分子電解質膜と、該高分子電解質膜の両面にそれぞれ設けられたカソード側触媒層およびアノード側触媒層と、該カソード側触媒層及び該アノード側触媒層のそれぞれの外側に設けられたアノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材とを有する膜−電極接合体であって、前記アノード側多孔質炭素電極基材および前記カソード側多孔質炭素電極基材の少なくとも一方として、前記の多孔質炭素電極基材が、表面処理された面を内側に向けて配置されている。   The membrane-electrode assembly of the present invention includes a polymer electrolyte membrane, a cathode side catalyst layer and an anode side catalyst layer provided on both sides of the polymer electrolyte membrane, the cathode side catalyst layer, and the anode side catalyst layer, respectively. A membrane-electrode assembly having an anode-side porous carbon electrode substrate and a cathode-side porous carbon electrode substrate provided on the outer sides of the anode-side porous carbon electrode substrate and the cathode side, respectively. As at least one of the porous carbon electrode substrates, the porous carbon electrode substrate is arranged with the surface-treated surface facing inward.

本発明の固体高分子型燃料電池は、高分子電解質膜と、該高分子電解質膜の両面にそれぞれ設けられたカソード側触媒層およびアノード側触媒層と、該カソード側触媒層および該アノード側触媒層のそれぞれの外側に設けられたアノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材と、該アノード側多孔質炭素電極基材および該カソード側多孔質炭素電極基材のそれぞれの外側に設けられたアノード側セパレーターおよびカソード側セパレーターと、を有する固体高分子型燃料電池であって、前記アノード側多孔質炭素電極基材および前記カソード側多孔質炭素電極基材の少なくとも一方として、前記の多孔質炭素電極基材が、表面処理された面を内側に向けて配置されている。   The solid polymer fuel cell of the present invention includes a polymer electrolyte membrane, a cathode side catalyst layer and an anode side catalyst layer provided on both sides of the polymer electrolyte membrane, the cathode side catalyst layer and the anode side catalyst, respectively. An anode-side porous carbon electrode base material and a cathode-side porous carbon electrode base material provided outside each of the layers, and each of the anode-side porous carbon electrode base material and the cathode-side porous carbon electrode base material A polymer electrolyte fuel cell having an anode side separator and a cathode side separator provided on the outside, and as at least one of the anode side porous carbon electrode substrate and the cathode side porous carbon electrode substrate, The porous carbon electrode substrate is arranged with the surface-treated surface facing inward.

本発明によれば、固体高分子型燃料電池に用いられる高分子電解質膜へのダメージを低減することができる多孔質炭素電極基材およびその製造方法、また、それを用いた固体高分子型燃料電池を提供できる。   ADVANTAGE OF THE INVENTION According to this invention, the porous carbon electrode base material which can reduce the damage to the polymer electrolyte membrane used for a polymer electrolyte fuel cell, its manufacturing method, and a polymer electrolyte fuel using the same Battery can be provided.

より具体的には、炭素短繊維を炭素により結着した炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分を取り除くための特定の表面処理を行うことで、表面近傍において炭素短繊維の両端が炭素によって結着している多孔質炭素電極基材を得ることが可能となり、多孔質炭素電極基材の物性値を変化させることなく、接合する高分子電解質膜へのダメージを低減し、これらを用いた固体高分子型燃料電池のリーク電流を低減し発電特性の低下を抑制でき、さらに固体高分子型燃料電池の耐久性を向上させることが可能となる。 More specifically, by performing a specific surface treatment for removing a fiber portion in which one end is not bound by carbon with respect to at least one surface of the carbon sheet in which short carbon fibers are bound by carbon, It is possible to obtain a porous carbon electrode base material in which both ends of short carbon fibers are bound by carbon in the vicinity of the surface, and the polymer electrolyte membrane to be joined without changing the physical property value of the porous carbon electrode base material Damage can be reduced, the leakage current of the polymer electrolyte fuel cell using these can be reduced, the deterioration of the power generation characteristics can be suppressed, and the durability of the polymer electrolyte fuel cell can be improved.

以下、本発明の実施形態について、図面を参照しながら、さらに詳細に説明する。   Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

図1は本発明に係る多孔質炭素電極基材を用いた膜−電極接合体および固体高分子型燃料電池の概略的構成図である。図1に示されるように、本実施形態に係る膜−電極接合体および固体高分子型燃料電池は、プロトン伝導性を有する高分子電解質膜1の一方の面に酸化ガス用触媒からなるカソード側触媒層2を、もう一方の面に燃料ガス用触媒からなるアノード側触媒層3を備えており、それぞれの触媒層2,3の外側には、カソード側多孔質炭素電極基材4およびアノード側多孔質炭素電極基材5が備えられている。ここで、高分子電解質膜1、触媒層2,3、および多孔質炭素電極基材4,5からなる部分が、膜−電極接合体6である。さらに、この膜−電極接合体6を挟持するように、カソード側ガス流路13が形成されたカソード側セパレーター7、およびアノード側ガス流路14が形成されたアノード側セパレーター8を備えている。また、それぞれのセパレーター7,8には、酸化ガス導入部9と酸化ガス排出部10、および燃料ガス導入部11と燃料ガス排出部12が備えられている。   FIG. 1 is a schematic configuration diagram of a membrane-electrode assembly and a polymer electrolyte fuel cell using a porous carbon electrode substrate according to the present invention. As shown in FIG. 1, the membrane-electrode assembly and the polymer electrolyte fuel cell according to this embodiment include a cathode side made of an oxidizing gas catalyst on one surface of a polymer electrolyte membrane 1 having proton conductivity. The catalyst layer 2 is provided with an anode side catalyst layer 3 made of a catalyst for fuel gas on the other side, and the cathode side porous carbon electrode substrate 4 and the anode side are provided outside the catalyst layers 2 and 3, respectively. A porous carbon electrode substrate 5 is provided. Here, the portion composed of the polymer electrolyte membrane 1, the catalyst layers 2 and 3, and the porous carbon electrode base materials 4 and 5 is the membrane-electrode assembly 6. Furthermore, a cathode-side separator 7 in which a cathode-side gas flow path 13 is formed and an anode-side separator 8 in which an anode-side gas flow path 14 is formed are provided so as to sandwich the membrane-electrode assembly 6. Each separator 7, 8 is provided with an oxidizing gas introducing part 9 and an oxidizing gas discharging part 10, and a fuel gas introducing part 11 and a fuel gas discharging part 12.

このような固体高分子型燃料電池において、燃料ガスは、燃料ガス導入部11から導入され、アノード側セパレーター8に形成されたアノード側ガス流路14からアノード側多孔質炭素電極基材5を介してアノード側触媒層3に供給され、プロトンと電子に解離される。この電子は、アノード側触媒層3からアノード側多孔質炭素電極基材5を介してアノード側セパレーター8に伝導され、外部の負荷に供給される。またプロトンは、高分子電解質膜1中を伝導し、カソード側へ移動する。一方、酸化ガスは、酸化ガス導入部9から導入され、カソード側セパレーター7に形成されたカソード側ガス流路13からカソード側多孔質炭素電極基材4を介してカソード側触媒層2に供給され、高分子電解質膜1中を伝導してきたプロトンと結合して水を生成する。このようにして所望の起電力が取り出せる。   In such a polymer electrolyte fuel cell, the fuel gas is introduced from the fuel gas introduction part 11 and from the anode side gas flow path 14 formed in the anode side separator 8 through the anode side porous carbon electrode substrate 5. Is supplied to the anode catalyst layer 3 and dissociated into protons and electrons. The electrons are conducted from the anode side catalyst layer 3 to the anode side separator 8 through the anode side porous carbon electrode base material 5 and supplied to an external load. Protons are conducted through the polymer electrolyte membrane 1 and move to the cathode side. On the other hand, the oxidizing gas is introduced from the oxidizing gas introduction part 9 and supplied to the cathode side catalyst layer 2 through the cathode side porous carbon electrode substrate 4 from the cathode side gas flow path 13 formed in the cathode side separator 7. In combination with protons conducted through the polymer electrolyte membrane 1, water is generated. In this way, a desired electromotive force can be taken out.

高分子電解質膜1としては、プロトン解離性の基、例えば−OH基、−OSO3H基、―COOH基、−SO3H基等が導入された高分子を用いることが好ましく、パーフルオロスルホン酸系の膜を用いることが、化学的安定性、プロトン伝導性の点よりさらに好ましい。 As the polymer electrolyte membrane 1, it is preferable to use a polymer into which proton dissociable groups such as —OH group, —OSO 3 H group, —COOH group, —SO 3 H group and the like are introduced. It is more preferable to use an acid film from the viewpoint of chemical stability and proton conductivity.

カソード側触媒層2およびアノード側触媒層3を構成する触媒としては、白金、白金合金、パラジウム、マグネシウム、バナジウム等があるが、白金または白金合金を用いることが好ましい。この触媒は、炭素粉末等の担体に担持されている状態で、各触媒層を構成していることが好ましい。   Examples of the catalyst constituting the cathode side catalyst layer 2 and the anode side catalyst layer 3 include platinum, platinum alloy, palladium, magnesium, vanadium, etc., but platinum or platinum alloy is preferably used. The catalyst preferably constitutes each catalyst layer in a state of being supported on a carrier such as carbon powder.

カソード側セパレーター7およびアノード側セパレーター8としては、従来と同様のセパレーターを用いることができる。   As the cathode-side separator 7 and the anode-side separator 8, the same separators as in the past can be used.

アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の少なくとも一方には、本発明に係る多孔質炭素電極基材を使用する。ここで、本発明に係る多孔質炭素電極基材は、炭素短繊維を炭素により結着した炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分を取り除くための特定の表面処理を行うことで製造される。そして、アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の少なくとも一方として、本発明に係る多孔質炭素電極基材が、表面処理された面を内側に向けて配置される。アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の両方に、本発明に係る多孔質炭素電極基材が、表面処理された面を内側に向けて配置されていることが好ましい。アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の一方に本発明に係る多孔質炭素電極基材を使用する場合、他方には従来と同様の多孔質炭素電極基材を用いることもできる。 The porous carbon electrode substrate according to the present invention is used for at least one of the anode side porous carbon electrode substrate and the cathode side porous carbon electrode substrate. Here, the porous carbon electrode substrate according to the present invention is for removing a fiber portion whose one end is not bound by carbon with respect to at least one surface of a carbon sheet in which short carbon fibers are bound by carbon. Manufactured by performing a specific surface treatment. And as at least one of an anode side porous carbon electrode base material and a cathode side porous carbon electrode base material, the porous carbon electrode base material which concerns on this invention is arrange | positioned facing the surface-treated surface inside. It is preferable that the porous carbon electrode substrate according to the present invention is disposed on both the anode side porous carbon electrode substrate and the cathode side porous carbon electrode substrate with the surface-treated surface facing inward. . When the porous carbon electrode substrate according to the present invention is used for one of the anode-side porous carbon electrode substrate and the cathode-side porous carbon electrode substrate, the same porous carbon electrode substrate as that used in the past is used for the other. You can also.

本発明に係る炭素電極基材は、炭素短繊維を炭素により結着した炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分を取り除くための特定の表面処理を行うことで製造されるものである。 The carbon electrode base material according to the present invention has a specific surface treatment for removing a fiber portion in which one end is not bound by carbon with respect to at least one surface of a carbon sheet in which short carbon fibers are bound by carbon. It is manufactured by doing.

炭素シートとしては、炭素短繊維を炭素により結着したものであれば用いることができるが、炭素多孔質フィルム、複数の炭素繊維が集合してなる織物や、複数本の炭素短繊維が集合してなる抄紙体が好ましく、表面平滑性が高く、電気的接触が良好で、かつ機械的強度が高い抄紙体がより好ましい。   As the carbon sheet, any carbon short fiber bonded with carbon can be used, but a carbon porous film, a woven fabric formed by a plurality of carbon fibers, and a plurality of carbon short fibers are assembled. A paper body having a high surface smoothness, good electrical contact and high mechanical strength is more preferable.

炭素短繊維としては、その原料によらず用いることができるが、ポリアクリロニトリル(以後PANと略す。)系炭素繊維、ピッチ系炭素繊維、レーヨン系炭素繊維、フェノール系炭素繊維から選ばれる1つ以上の炭素繊維を含むことが好ましく、PAN系炭素繊維を含むことがより好ましい。   The short carbon fiber can be used regardless of the raw material, but one or more selected from polyacrylonitrile (hereinafter abbreviated as PAN) carbon fiber, pitch carbon fiber, rayon carbon fiber, and phenolic carbon fiber. It is preferable that the carbon fiber is included, and it is more preferable that the PAN-based carbon fiber is included.

炭素短繊維の平均直径は、表面平滑性、導電性の付与のためには3〜30μm程度が好ましく、4〜20μmがより好ましく、4〜8μmがさらに好ましい。また、異なる平均直径の炭素短繊維を2種類以上用いることも、表面平滑性、導電性の両立のために好ましい。   The average diameter of the short carbon fibers is preferably about 3 to 30 μm, more preferably 4 to 20 μm, and even more preferably 4 to 8 μm for imparting surface smoothness and conductivity. It is also preferable to use two or more types of short carbon fibers having different average diameters in order to achieve both surface smoothness and conductivity.

炭素短繊維の長さは、抄紙時の分散性、および機械的強度を高めるために、2mm以上12mm以下が好ましく、3mm以上9mm以下がさらに好ましい。   The length of the short carbon fiber is preferably 2 mm or more and 12 mm or less, and more preferably 3 mm or more and 9 mm or less in order to improve the dispersibility during papermaking and the mechanical strength.

炭素短繊維を互いに結着させるための炭素材としては、樹脂を加熱によって炭素化して得られる炭素材を用いることができる。このために用いる樹脂としては、炭素化した段階で多孔質炭素電極基材の炭素繊維を結着することのできる公知の樹脂から適宜選んで用いることができる。炭素化後に導電性物質として残存しやすいという観点から、フェノール樹脂、エポキシ樹脂、フラン樹脂、ピッチ等が好ましく、加熱による炭素化の際の炭化率の高いフェノール樹脂が特に好ましい。   As a carbon material for binding the short carbon fibers to each other, a carbon material obtained by carbonizing a resin by heating can be used. The resin used for this purpose can be appropriately selected from known resins that can bind the carbon fibers of the porous carbon electrode substrate at the stage of carbonization. From the viewpoint of easily remaining as a conductive substance after carbonization, a phenol resin, an epoxy resin, a furan resin, pitch, and the like are preferable, and a phenol resin having a high carbonization rate upon carbonization by heating is particularly preferable.

炭素材の炭素化は、不活性ガス中において1500〜2200℃で焼成することで行うことができる。   Carbonization of the carbon material can be performed by firing at 1500 to 2200 ° C. in an inert gas.

図2は、本発明に係る多孔質炭素電極基材の一例を示す略斜視図である。図2に示すように、炭素シートは複数の炭素短繊維が炭素による結着部17で結着しており、両端が炭素により結着している繊維部分16と、一端が炭素により結着していない繊維部分15とを有している。本発明に係る多孔質炭素電極基材は、この炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分15を取り除くための特定の表面処理を行うことで製造する。すなわち、本発明に係る多孔質炭素電極基材の少なくとも一方の表面部分では、一端が炭素により結着していない繊維部分15の大部分が取り除かれており、少なくとも一方の表面部分に存在する炭素短繊維のほとんどが両端を炭素によって結着されている繊維部分16となっている。膜−電極接合体や固体高分子型燃料電池において、このような本発明に係る多孔質炭素電極基材を、表面処理された面を内側に向けて配置することで、膜−電極接合体の組み立て時、固体高分子型燃料電池セルの作製時または発電時の加圧による炭素短繊維および炭素化された樹脂の脱落や突き刺さりによる高分子電解質膜へのダメージを低減できる。 FIG. 2 is a schematic perspective view showing an example of a porous carbon electrode substrate according to the present invention. As shown in FIG. 2, in the carbon sheet, a plurality of short carbon fibers are bound by a binding portion 17 made of carbon, and both ends are bound by carbon, and one end is bound by carbon. The fiber portion 15 is not included. The porous carbon electrode substrate according to the present invention is manufactured by performing a specific surface treatment for removing the fiber portion 15 whose one end is not bound by carbon on at least one surface of the carbon sheet. . That is, in at least one surface portion of the porous carbon electrode substrate according to the present invention, most of the fiber portions 15 whose one ends are not bound by carbon are removed, and carbon existing in at least one surface portion is present. Most of the short fibers are fiber portions 16 bound at both ends by carbon. In a membrane-electrode assembly or a polymer electrolyte fuel cell, the porous carbon electrode substrate according to the present invention is disposed with the surface-treated surface facing inward, so that the membrane-electrode assembly It is possible to reduce damage to the polymer electrolyte membrane caused by dropping or piercing of the carbon short fibers and the carbonized resin due to pressurization during assembly, production of a solid polymer fuel cell, or power generation.

なお、両端が炭素により結着している繊維部分であるか、一端が炭素に結着していない繊維部分であるかは、光学顕微鏡観察を行うことにより判別することができる。   In addition, it can be discriminate | determined by observing with an optical microscope whether it is a fiber part which the both ends are bound to carbon, or one end is a fiber part which is not bound to carbon.

一端が炭素により結着していない繊維部分を取り除くための表面処理の方法としては、例えば、炭素シートの少なくとも一方の表面を吸引する方法、炭素シートの少なくとも一方の表面を刷毛で刷く方法、が挙げられる。しかしながら、本発明では、上記表面処理の方法として、炭素シートの少なくとも一方の表面を吸引仕事率が100〜700Wの吸引装置によって、1〜20秒吸引する方法を用いる。特に、一端が炭素により結着していない繊維部分をより効率的かつ十分に取り除くため、炭素シートの少なくとも一方の表面を吸引しつつ、その表面を刷毛で刷く方法が好ましい。 Examples of the surface treatment method for removing the fiber portion whose one end is not bound by carbon include, for example, a method of sucking at least one surface of the carbon sheet, a method of printing at least one surface of the carbon sheet with a brush, Is mentioned. However, in the present invention, as the surface treatment method, a method is used in which at least one surface of the carbon sheet is sucked by a suction device having a suction power of 100 to 700 W for 1 to 20 seconds. In particular, in order to more efficiently and sufficiently remove the fiber portion that is not bound by carbon at one end, a method of drawing the surface with a brush while sucking at least one surface of the carbon sheet is preferable.

表面を吸引する方法としては、吸引装置を用いる。具体的には、吸引仕事率が100〜700Wの吸引装置を用いて、1〜20秒吸引する。 As a method of sucking the surface, Ru using a suction device. Specifically, the suction work rate by using a suction device 100~700W, suction 1-20 seconds.

刷毛は、多孔質炭素電極基材を構成する炭素材料と同等またはそれよりやわらかい材質が好ましく、例えば、獣毛や合成繊維の刷毛が好適である。   The brush is preferably made of a material equivalent to or softer than the carbon material constituting the porous carbon electrode substrate. For example, animal hair or synthetic fiber brush is suitable.

表面を吸引しつつ刷毛で刷く方法としては、吸引装置の吸引口の周囲に刷毛を固定し、炭素シートの表面を掃きながら吸引することが好ましい。また、吸引装置の吸引口の内部に回転する刷毛を取り付け、炭素シートの表面を吸引することも好ましい。   As a method of brushing with the brush while sucking the surface, it is preferable that the brush is fixed around the suction port of the suction device and sucked while sweeping the surface of the carbon sheet. It is also preferable to attach a rotating brush inside the suction port of the suction device and suck the surface of the carbon sheet.

本発明に係る多孔質炭素電極基材は、少なくとも一方の表面から炭素短繊維の平均直径の3倍以内の厚み範囲内に存在する炭素短繊維に対して、表面処理がされることが好ましい。これにより、炭素シートの物性値を変化させることなく、高分子電解質膜へのダメージが低減され、高分子電解質膜の両面に配置されたアノードとカソード間を高分子電解質膜を介して短絡するリーク電流を抑制することができる。   The porous carbon electrode substrate according to the present invention is preferably subjected to a surface treatment on carbon short fibers existing within a thickness range within 3 times the average diameter of the carbon short fibers from at least one surface. This reduces the damage to the polymer electrolyte membrane without changing the physical properties of the carbon sheet, and leaks the anode and cathode disposed on both sides of the polymer electrolyte membrane via the polymer electrolyte membrane. Current can be suppressed.

より具体的には、本発明に係る多孔質炭素電極基材において、表面処理を行った表面から炭素短繊維の平均直径の3倍以内の厚み範囲内に存在する炭素短繊維のうち、両端が炭素により結着している繊維部分が80本数%以上であることが好ましい。この割合は90本数%以上がより好ましく、95本数%以上がさらに好ましい。これにより、高分子電解質膜へのダメージが低減され、高分子電解質膜の両面に配置されたアノードとカソード間を高分子電解質膜を介して短絡するリーク電流を抑制することができる。また、高分子電解質膜のダメージを低減することより、発電時の耐久性の向上にも寄与することが予想される。さらに高分子電解質膜へのダメージが低減することにより、厚みが薄い膜を用いることが容易になり、固体高分子型燃料電池の発電性能を高めることが可能となる。   More specifically, in the porous carbon electrode substrate according to the present invention, both ends of the carbon short fibers existing within a thickness range within 3 times the average diameter of the carbon short fibers from the surface subjected to the surface treatment. It is preferable that the number of fiber portions bound by carbon is 80% or more. This ratio is more preferably 90% or more and more preferably 95% or more. Thereby, damage to the polymer electrolyte membrane is reduced, and a leakage current that short-circuits between the anode and the cathode disposed on both surfaces of the polymer electrolyte membrane via the polymer electrolyte membrane can be suppressed. In addition, it is expected to contribute to improvement of durability during power generation by reducing damage to the polymer electrolyte membrane. Further, since the damage to the polymer electrolyte membrane is reduced, it becomes easy to use a thin membrane, and the power generation performance of the solid polymer fuel cell can be improved.

なお、炭素短繊維の直径は、光学顕微鏡観察又は電子顕微鏡観察により測定できる。また、ランダムに20本の炭素短繊維の直径を測定し、その平均を炭素短繊維の平均直径とした。   The diameter of the short carbon fiber can be measured by optical microscope observation or electron microscope observation. Moreover, the diameter of 20 carbon short fibers was measured at random, and the average was made into the average diameter of carbon short fibers.

固体高分子型燃料電池では、カソード側において電極反応生成物としての水や高分子電解質膜を浸透した水が発生する。また、アノード側において高分子電解質膜の乾燥を抑制するために加湿された燃料が供給される。そこで、本発明に係る多孔質炭素電極基材は、加湿ガス雰囲気下でのガス透過性を確保するために、撥水剤として撥水性の高分子を含むこともできる。撥水性の高分子としては、化学的に安定でかつ高い撥水性を有する、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−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−パーフルオロアルキルビニルエーテル共重合体(PFA)などのフッ素樹脂を用いることが好ましい。   In a polymer electrolyte fuel cell, water as an electrode reaction product and water penetrating a polymer electrolyte membrane are generated on the cathode side. Further, humidified fuel is supplied on the anode side to suppress drying of the polymer electrolyte membrane. Therefore, the porous carbon electrode substrate according to the present invention can also contain a water-repellent polymer as a water-repellent agent in order to ensure gas permeability in a humidified gas atmosphere. As the water-repellent polymer, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether, which is chemically stable and has high water repellency. It is preferable to use a fluororesin such as a copolymer (PFA).

撥水性の高分子を多孔質炭素電極基材へ導入する方法としては、撥水性の高分子の微粒子が分散した分散液中に多孔質炭素電極基材を浸漬させるディップ法、分散液を噴霧するスプレー法などが好ましい。   As a method for introducing the water-repellent polymer into the porous carbon electrode substrate, a dip method in which the porous carbon electrode substrate is immersed in a dispersion in which fine particles of the water-repellent polymer are dispersed, or spraying the dispersion A spray method or the like is preferable.

〔実施例1〕
炭素短繊維として、長さ3mmにカットした平均直径4μmのPAN系炭素短繊維を30質量%と、長さ3mmにカットした平均直径7μmのPAN系炭素短繊維を70質量%とからなる炭素短繊維100質量部と、長さ3mmのポリビニルアルコール(PVA)繊維(商品名:VBP105−1、クラレ株式会社製)を28質量部とを水中で分散し、連続的に金網上に抄造した後、乾燥して炭素繊維紙を得た。
[Example 1]
Short carbon fibers comprising 30% by mass of PAN-based carbon short fibers having an average diameter of 4 μm cut to a length of 3 mm and 70% by mass of PAN-based carbon short fibers having an average diameter of 7 μm cut to a length of 3 mm. After 100 parts by mass of fibers and 28 parts by mass of polyvinyl alcohol (PVA) fibers having a length of 3 mm (trade name: VBP105-1, manufactured by Kuraray Co., Ltd.) are dispersed in water and continuously made on a wire mesh, Carbon fiber paper was obtained by drying.

この炭素繊維紙100質量部に、フェノール樹脂(商品名:フェノライトJ−325、大日本インキ化学株式会社製)のメタノール溶液を含浸させ、室温でメタノールを十分に乾燥させ、フェノール樹脂の不揮発分を90質量部付着させたフェノール樹脂含浸炭素繊維紙を得た。   100 parts by mass of this carbon fiber paper is impregnated with a methanol solution of a phenol resin (trade name: Phenolite J-325, manufactured by Dainippon Ink and Chemicals), and the methanol is sufficiently dried at room temperature, so that the nonvolatile content of the phenol resin 90 mass parts of phenol resin impregnated carbon fiber paper was obtained.

このフェノール樹脂含浸炭素繊維紙を2枚重ねて、250℃の温度で8×104N/mの線力のロールプレスを行い、フェノール樹脂を硬化させた。その後、不活性ガス(窒素)雰囲気中、1900℃で連続的に炭素化して、炭素短繊維の抄紙体からなる炭素シートを得た。 Two sheets of this phenol resin-impregnated carbon fiber paper were stacked and roll-pressed at a linear force of 8 × 10 4 N / m at a temperature of 250 ° C. to cure the phenol resin. Then, it carbonized continuously at 1900 degreeC in inert gas (nitrogen) atmosphere, and obtained the carbon sheet which consists of a papermaking body of a carbon short fiber.

この炭素シートの片方の表面を、羊毛を用いた刷毛(直径が2.5cm、長さ5cmの化粧用の刷毛)を吸引口の周りに3本取り付け、吸引口がほとんど刷毛で覆われるように固定した吸引装置を用いて、吸引しながら刷毛で同じ箇所を10回ほど刷くことにより、多孔質炭素電極基材を得た。この吸引装置の吸引仕事率は260Wであり、吸引時間は10秒とした。得られた多孔質炭素電極基材は、リーク電流が87nA/cm2と低く良好な特性を示した。 Attach three brushes (2.5cm diameter, 5cm length cosmetic brush) around the suction port to the surface of one side of the carbon sheet so that the suction port is almost covered with the brush. A porous carbon electrode substrate was obtained by printing the same portion about 10 times with a brush while suctioning using a fixed suction device. The suction power of this suction device was 260 W, and the suction time was 10 seconds. The obtained porous carbon electrode substrate showed a good characteristic with a low leakage current of 87 nA / cm 2 .

なお、各多孔質炭素電極基材について、測定したリーク電流及び厚みの結果を表1に示す。   Table 1 shows the results of the measured leakage current and thickness for each porous carbon electrode substrate.

〔実施例2〕
実施例1と同様の方法で得られた炭素シートの片方の表面を、合成繊維を用いた刷毛を吸引口の中で回転するように取り付けた吸引装置を用いて、吸引しながら刷毛を回転させることにより、多孔質炭素電極基材を得た。この吸引装置の吸引仕事率は260Wであり、吸引時間は5秒とした。なお、刷毛が取り付けられた吸引口部分としては、三洋電機製の布団ローラー(商品名:アトピットターボ(型番:SCS−ATP20(L)))を用い、5回程度同じ箇所を刷いた。得られた多孔質炭素電極基材は、リーク電流が88nA/cm2と低く良好な特性を示した。
[Example 2]
The brush is rotated while sucking one surface of the carbon sheet obtained by the same method as in Example 1 using a suction device in which the brush using the synthetic fiber is rotated in the suction port. As a result, a porous carbon electrode substrate was obtained. The suction power of this suction device was 260 W, and the suction time was 5 seconds. In addition, as a suction port portion to which the brush was attached, a duvet roller (trade name: Atopit Turbo (model number: SCS-ATP20 (L))) manufactured by Sanyo Electric Co., Ltd. was used, and the same portion was printed about five times. The obtained porous carbon electrode substrate showed a good characteristic with a low leak current of 88 nA / cm 2 .

〔実施例3〕
炭素短繊維として、長さ3mmにカットした平均直径4μmのPAN系炭素短繊維のみからなる炭素短繊維100質量部を使用した以外は、実施例1と同様にして多孔質炭素電極基材を得た。得られた多孔質炭素電極基材は、リーク電流が77nA/cm2と低く良好な特性を示した。
Example 3
A porous carbon electrode substrate was obtained in the same manner as in Example 1 except that 100 parts by mass of carbon short fibers consisting only of PAN-based carbon short fibers having an average diameter of 4 μm cut to a length of 3 mm were used as the carbon short fibers. It was. The obtained porous carbon electrode substrate showed a good characteristic with a low leak current of 77 nA / cm 2 .

〔実施例4〕
炭素短繊維として、長さ3mmにカットした平均直径7μmのPAN系炭素短繊維のみからなる炭素短繊維100質量部を使用した以外は、実施例1と同様にして多孔質炭素電極基材を得た。得られた多孔質炭素電極基材は、リーク電流が83nA/cm2と低く良好な特性を示した。
Example 4
A porous carbon electrode substrate was obtained in the same manner as in Example 1 except that 100 parts by mass of carbon short fibers consisting only of PAN-based carbon short fibers cut to a length of 3 mm and having an average diameter of 7 μm were used as the carbon short fibers. It was. The obtained porous carbon electrode substrate showed a good characteristic with a low leakage current of 83 nA / cm 2 .

〔実施例5〕
吸引の際に刷毛で刷かなかったこと以外は、実施例1と同様にして多孔質炭素電極基材を得た。得られた多孔質炭素電極基材は、リーク電流が114nA/cm2であり、実施例1および2と比較して高いリーク電流を示した。
Example 5
A porous carbon electrode substrate was obtained in the same manner as in Example 1 except that it was not printed with a brush at the time of suction. The obtained porous carbon electrode base material had a leak current of 114 nA / cm 2 , and showed a higher leak current than Examples 1 and 2.

〔実施例6〕
吸引せずに刷毛で刷いたこと以外は、実施例1と同様にして多孔質炭素電極基材を得た。得られた多孔質炭素電極基材は、リーク電流が115nA/cm2であり、実施例1および2と比較して高いリーク電流を示した。なお、この実施例6は参考例である。
Example 6
A porous carbon electrode substrate was obtained in the same manner as in Example 1 except that the brush was printed with a brush without suction. The obtained porous carbon electrode base material had a leakage current of 115 nA / cm 2 , and showed a higher leakage current than Examples 1 and 2. This Example 6 is a reference example.

〔比較例1〕
実施例1と同様の方法で得られた炭素シートを、吸引も刷毛で刷くこともせずに、そのまま多孔質炭素電極基材とした。得られた多孔質炭素電極基材は、リーク電流が127nA/cm2であり、実施例5および6と比較してさらに高いリーク電流を示した。
[Comparative Example 1]
The carbon sheet obtained by the same method as in Example 1 was used as it was as a porous carbon electrode substrate without being sucked or printed with a brush. The obtained porous carbon electrode base material had a leak current of 127 nA / cm 2 , which was higher than that of Examples 5 and 6.

〔比較例2〕
実施例3と同様の方法で得られた炭素シートを、吸引も刷毛で刷くこともせずに、そのまま多孔質炭素電極基材とした。得られた多孔質炭素電極基材は、リーク電流が148nA/cm2であり、実施例3と比較してさらに高いリーク電流を示した。
[Comparative Example 2]
The carbon sheet obtained by the same method as in Example 3 was used as it was as a porous carbon electrode base material without suction or brushing. The obtained porous carbon electrode base material had a leakage current of 148 nA / cm 2 , and showed a higher leakage current than that of Example 3.

〔比較例3〕
実施例4と同様の方法で得られた炭素シートを、吸引も刷毛で刷くこともせずに、そのまま多孔質炭素電極基材とした。得られた多孔質炭素電極基材は、リーク電流が95nA/cm2であり、実施例4と比較してさらに高いリーク電流を示した。
[Comparative Example 3]
The carbon sheet obtained by the same method as in Example 4 was used as it was as a porous carbon electrode substrate without suction or brushing. The obtained porous carbon electrode base material had a leakage current of 95 nA / cm 2 , and showed a higher leakage current than that of Example 4.

Figure 0005106808
Figure 0005106808

〔リーク電流の測定方法〕
パーフルオロスルホン酸系の高分子電解質膜(膜厚:30μm)の両面に、得られた多孔質炭素電極基材の表面処理した面(比較例1〜3の場合は、いずれか一方の面)が接するように配置し、それを金メッキした銅板電極ではさみ、1.0MPaまで加圧した後、超高抵抗/微少電流計R8340(商品名、アドバンテスト社製)を使用し、高分子電解質膜へのダメージによるリーク電流を測定した。なお、このときの電極間の電位差は1.0Vで行った。
[Measurement method of leakage current]
Surface treated surface of the obtained porous carbon electrode base material on both sides of a perfluorosulfonic acid polymer electrolyte membrane (film thickness: 30 μm) (in the case of Comparative Examples 1 to 3, either surface) Is placed in contact with each other, sandwiched between gold-plated copper plate electrodes, pressurized to 1.0 MPa, and then applied to a polymer electrolyte membrane using an ultrahigh resistance / microammeter R8340 (trade name, manufactured by Advantest). Leakage current due to damage was measured. At this time, the potential difference between the electrodes was 1.0 V.

〔厚みの測定方法〕
厚み測定装置ダイヤルシックネスゲージ7321(商品名、ミツトヨ社製)を使用し、測定した。なお、このときの測定子の大きさは、直径10mmで測定圧力は1.5kPaで行った。
[Measurement method of thickness]
The thickness was measured using a dial thickness gauge 7321 (trade name, manufactured by Mitutoyo Corporation). Note that the size of the probe at this time was 10 mm in diameter and the measurement pressure was 1.5 kPa.

〔実施例7〕
(1)MEAの作製
実施例1で得られた多孔質炭素電極基材をカソード用、アノード用に2組用意した。両面に触媒担持カーボン(触媒:Pt、触媒担持量:50質量%)からなる触媒層(触媒層面積:25cm2、Pt付着量:0.3mg/cm2)を形成したパーフルオロスルホン酸系の高分子電解質膜(膜厚:30μm)を、この2組の多孔質炭素電極基材の表面処理した面を内側として挟持し、これらを接合してMEAを得た。
Example 7
(1) Production of MEA Two sets of the porous carbon electrode base material obtained in Example 1 were prepared for the cathode and the anode. Perfluorosulfonic acid based catalyst in which a catalyst layer (catalyst layer area: 25 cm 2 , Pt adhesion amount: 0.3 mg / cm 2 ) made of catalyst-supported carbon (catalyst: Pt, catalyst support amount: 50% by mass) is formed on both surfaces. The polymer electrolyte membrane (film thickness: 30 μm) was sandwiched with the surface-treated surfaces of the two sets of porous carbon electrode substrates as the inside, and these were joined to obtain MEA.

(2)MEAの燃料電池特性評価
前記(1)において作製したMEAを、蛇腹状のガス流路を有する2枚のカーボンセパレーターによってはさみ、固体高分子型燃料電池(単セル)を形成した。
(2) Evaluation of MEA Fuel Cell Characteristics The MEA produced in (1) above was sandwiched between two carbon separators having bellows-like gas flow paths to form a solid polymer fuel cell (single cell).

この単セルについて、電流密度−電圧特性を測定することによって、燃料電池特性評価を行った。燃料ガスとしては水素ガスを用い、酸化ガスとしては空気を用いた。測定条件としては、セル温度を80℃、燃料ガス利用率を60%、酸化ガス利用率を40%とした。また、ガス加湿は、70℃のバブラーにそれぞれ燃料ガスと酸化ガスを通すことによって行った。   This single cell was evaluated for fuel cell characteristics by measuring current density-voltage characteristics. Hydrogen gas was used as the fuel gas, and air was used as the oxidizing gas. As measurement conditions, the cell temperature was 80 ° C., the fuel gas utilization rate was 60%, and the oxidizing gas utilization rate was 40%. Gas humidification was performed by passing fuel gas and oxidizing gas through a bubbler at 70 ° C., respectively.

その結果、電流密度が0.4A/cm2のときの燃料電池セルのセル電圧は0.677Vであり、また開回路電圧が0.941Vと高く、アノード、カソード間のクロスリークおよび微少ショートが小さく良好な特性を示した。 As a result, when the current density is 0.4 A / cm 2 , the cell voltage of the fuel cell is 0.677 V, the open circuit voltage is as high as 0.941 V, and cross leaks and minute shorts between the anode and the cathode are observed. Small and good characteristics.

〔比較例4〕
比較例1で得られた多孔質炭素電極基材を用いたこと以外は、実施例7と同様にして単セルを組み立て、燃料電池特性評価を行った。
[Comparative Example 4]
A single cell was assembled in the same manner as in Example 7 except that the porous carbon electrode substrate obtained in Comparative Example 1 was used, and the fuel cell characteristics were evaluated.

その結果、電流密度が0.4A/cm2のときの燃料電池セルのセル電圧は0.677Vであったが、開回路電圧が0.918Vと実施例7より低下しており、アノード、カソード間のクロスリークおよび微少ショートが実施例7より増加した特性を示した。 As a result, the cell voltage of the fuel cell when the current density was 0.4 A / cm 2 was 0.677 V, but the open circuit voltage was 0.918 V, which is lower than that of Example 7, and the anode, cathode The cross-leakage and the micro short circuit between them showed the characteristics increased from those of Example 7.

本発明の固体高分子型燃料電池の一形態を示す模式的断面図である。It is a typical sectional view showing one form of a polymer electrolyte fuel cell of the present invention. 本発明の多孔質炭素電極基材の一形態を示す略断面図である。It is a schematic sectional drawing which shows one form of the porous carbon electrode base material of this invention.

符号の説明Explanation of symbols

1:高分子電解質膜
2:カソード側触媒層
3:アノード側触媒層
4:カソード側多孔質炭素電極基材
5:アノード側多孔質炭素電極基材
6:膜−電極接合体(MEA)
7:カソード側セパレーター
8:アノード側セパレーター
9:酸化ガス導入部
10:酸化ガス排出部
11:燃料ガス導入部
12:燃料ガス排出部
13:カソード側ガス流路
14:アノード側ガス流路
15:一端が炭素により結着していない繊維部分
16:両端が炭素により結着している繊維部分
17:炭素による結着部
1: Polymer electrolyte membrane 2: Cathode side catalyst layer 3: Anode side catalyst layer 4: Cathode side porous carbon electrode base material 5: Anode side porous carbon electrode base material 6: Membrane-electrode assembly (MEA)
7: Cathode side separator 8: Anode side separator 9: Oxidizing gas introduction part 10: Oxidizing gas discharge part 11: Fuel gas introduction part 12: Fuel gas discharge part 13: Cathode side gas flow path 14: Anode side gas flow path 15: Fiber part 16 with one end not bound by carbon: Fiber part 17 with both ends bound by carbon 17: Binding part by carbon

Claims (8)

炭素短繊維を炭素により結着した炭素シートの少なくとも一方の表面に対して、一端が炭素により結着していない繊維部分を取り除くための表面処理を行い、その際、該表面処理として、該炭素シートの少なくとも一方の表面を、吸引仕事率が100〜700Wの吸引装置によって、1〜20秒吸引する多孔質炭素電極基材の製造方法。 The short carbon fibers to at least one surface of the carbon sheets bound by a carbon, one end had the row a surface treatment for removing a fiber portion not bound by a carbon, in which, as the surface treatment, the A method for producing a porous carbon electrode base material, wherein at least one surface of a carbon sheet is sucked by a suction device having a suction power of 100 to 700 W for 1 to 20 seconds . 前記吸引装置が、該吸引装置の吸引口の周囲に固定される刷毛、および該吸引装置の吸引口の内部に取り付けられる回転する刷毛から選ばれる刷毛を備える請求項1に記載の多孔質炭素電極基材の製造方法。The porous carbon electrode according to claim 1, wherein the suction device comprises a brush selected from a brush fixed around the suction port of the suction device and a rotating brush attached to the inside of the suction port of the suction device. A method for producing a substrate. 前記表面処理として、前記炭素シートの少なくとも一方の表面を、吸引仕事率が100〜700Wの吸引装置によって、1〜20秒吸引しつつ、該表面を刷毛で刷く請求項1または2に記載の多孔質炭素電極基材の製造方法。 As the surface treatment, at least one surface of the carbon sheet, the suction work rate is the suction device 100~700W, while suction 20 seconds, according to the surface on the printing rather claim 1 or 2 with a brush A method for producing a porous carbon electrode substrate. 前記炭素短繊維の平均直径が3〜30μmであって、かつ、該炭素短繊維の長さが2mm以上12mm以下である請求項1〜3のいずれかに記載の多孔質炭素電極基材の製造方法。The average diameter of the carbon short fibers is 3 to 30 µm, and the length of the carbon short fibers is 2 mm or more and 12 mm or less. Production of a porous carbon electrode substrate according to any one of claims 1 to 3 Method. 請求項1〜4のいずれかに記載の方法により製造される多孔質炭素電極基材。   The porous carbon electrode base material manufactured by the method in any one of Claims 1-4. 前記表面処理を行った表面から前記炭素短繊維の平均直径の3倍以内の厚み範囲内に存在する炭素短繊維のうち、両端が炭素により結着している繊維部分が80本数%以上である請求項5に記載の多孔質炭素電極基材。   Of the carbon short fibers present within a thickness range within 3 times the average diameter of the carbon short fibers from the surface that has been subjected to the surface treatment, 80% or more of the fiber portions are bound by carbon at both ends. The porous carbon electrode substrate according to claim 5. 高分子電解質膜と、該高分子電解質膜の両面にそれぞれ設けられたカソード側触媒層およびアノード側触媒層と、該カソード側触媒層および該アノード側触媒層のそれぞれの外側に設けられたアノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材とを有する膜−電極接合体であって、
前記アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の少なくとも一方として、請求項5または6記載の多孔質炭素電極基材が、表面処理された面を内側に向けて配置されている膜−電極接合体。
A polymer electrolyte membrane; a cathode side catalyst layer and an anode side catalyst layer provided on both sides of the polymer electrolyte membrane; and an anode side provided on the outside of each of the cathode side catalyst layer and the anode side catalyst layer A membrane-electrode assembly having a porous carbon electrode substrate and a cathode-side porous carbon electrode substrate,
As at least one of the anode side porous carbon electrode substrate and the cathode side porous carbon electrode substrate, the porous carbon electrode substrate according to claim 5 or 6 Symbol mounting is, toward the surface-treated surface on the inside arrangement A membrane-electrode assembly.
高分子電解質膜と、該高分子電解質膜の両面にそれぞれ設けられたカソード側触媒層およびアノード側触媒層と、該カソード側触媒層および該アノード側触媒層のそれぞれの外側に設けられたアノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材と、該アノード側多孔質炭素電極基材および該カソード側多孔質炭素電極基材のそれぞれの外側に設けられたアノード側セパレーターおよびカソード側セパレーターと、を有する固体高分子型燃料電池であって、
前記アノード側多孔質炭素電極基材およびカソード側多孔質炭素電極基材の少なくとも一方として、請求項5または6記載の多孔質炭素電極基材が、表面処理された面を内側に向けて配置されている固体高分子型燃料電池。
A polymer electrolyte membrane; a cathode side catalyst layer and an anode side catalyst layer provided on both sides of the polymer electrolyte membrane; and an anode side provided on the outside of each of the cathode side catalyst layer and the anode side catalyst layer Porous carbon electrode base material and cathode side porous carbon electrode base material, and anode side separator and cathode side provided outside each of the anode side porous carbon electrode base material and the cathode side porous carbon electrode base material A polymer electrolyte fuel cell having a separator,
As at least one of the anode side porous carbon electrode substrate and the cathode side porous carbon electrode substrate, the porous carbon electrode substrate according to claim 5 or 6 Symbol mounting is, toward the surface-treated surface on the inside arrangement Solid polymer fuel cell.
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