JP2008269929A - Fuel battery - Google Patents

Fuel battery Download PDF

Info

Publication number
JP2008269929A
JP2008269929A JP2007110588A JP2007110588A JP2008269929A JP 2008269929 A JP2008269929 A JP 2008269929A JP 2007110588 A JP2007110588 A JP 2007110588A JP 2007110588 A JP2007110588 A JP 2007110588A JP 2008269929 A JP2008269929 A JP 2008269929A
Authority
JP
Japan
Prior art keywords
water
repellent layer
layer
repellent
fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2007110588A
Other languages
Japanese (ja)
Other versions
JP5036384B2 (en
Inventor
Masahiro Shiozawa
方浩 塩澤
Masanori Uehara
昌徳 上原
Hitoshi Hamada
仁 濱田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Denso Corp
Toyota Motor Corp
Soken Inc
Original Assignee
Denso Corp
Nippon Soken Inc
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Denso Corp, Nippon Soken Inc, Toyota Motor Corp filed Critical Denso Corp
Priority to JP2007110588A priority Critical patent/JP5036384B2/en
Publication of JP2008269929A publication Critical patent/JP2008269929A/en
Application granted granted Critical
Publication of JP5036384B2 publication Critical patent/JP5036384B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Landscapes

  • Fuel Cell (AREA)
  • Inert Electrodes (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell free from quick degradation of power generation performance even though generated water starts to freeze in a fuel battery cell and enabled to start up at a sub-zero temperature without increasing the number of system structural components by securing an amount of heat generation through continuation of power generation. <P>SOLUTION: In the cell C of a fuel battery stack S, an oxidant gas side separator 4 and a fuel gas side separator 5 are arranged on both sides of an electrolyte membrane 11 by holding a MEA (membrane electrode assembly) 1 having an electrode made of electrolyte layers 21, 22 and diffusion layers 31, 32. An air flow passage 41 is formed on the oxidant gas side separator 4, and a hydrogen flow passage 51 is formed on the fuel gas side separator 5. The diffusion layers 31, 32 have a water-repellent layer 3 made of a strong water-repellent layer 3a and a weak water-repellent layer 3b on the surface at the electrolyte layers 21, 22 side. Water and liquid on an interface between the electrolyte layers 21, 22 and diffusion layers 31, 32 are cut off to prevent transmission of freezing by alternately arranging the strong water-repellent layer 3a and weak water-repellent layer 3b in parallel along the gas-flowing direction of the air flow passage 41 and hydrogen flow passage 51. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、燃料ガスと酸化剤ガスの化学反応を利用して発電する燃料電池に関し、特に、氷点下始動時における生成水の凍結を回避できる燃料電池セル構成に関するものである。   The present invention relates to a fuel cell that generates power using a chemical reaction between a fuel gas and an oxidant gas, and more particularly to a fuel cell configuration that can avoid freezing of generated water at the time of starting below freezing.

固体高分子型燃料電池は、複数のセルを積層した燃料電池スタックに、酸素を含有する酸化剤ガスと水素を含有する燃料ガスを供給して化学反応させることにより電気エネルギーを発生させている。基本単位となるセルは、一般に、固体高分子電解質膜の両面に電極となる触媒層と拡散層を形成したＭＥＡ（Membrane Electrode Assembly）と呼ばれる膜電極接合体を備え、その外側に酸化剤ガス側セパレータ、燃料ガス側セパレータを配設した構造となっている。酸化剤ガス側セパレータ、燃料ガス側セパレータと、拡散層の間には、それぞれ酸化剤ガス流路、燃料ガス流路が形成されている。   In the polymer electrolyte fuel cell, electric energy is generated by supplying a chemical reaction by supplying an oxidant gas containing oxygen and a fuel gas containing hydrogen to a fuel cell stack in which a plurality of cells are stacked. A cell that is a basic unit generally includes a membrane electrode assembly called MEA (Membrane Electrode Assembly) in which a catalyst layer and a diffusion layer are formed on both sides of a solid polymer electrolyte membrane. The separator and the fuel gas side separator are arranged. An oxidant gas flow path and a fuel gas flow path are formed between the oxidant gas side separator, the fuel gas side separator, and the diffusion layer, respectively.

燃料極（アノード）では、燃料ガス流路から拡散層を経て供給される水素が触媒層の触媒作用によりイオン化し、電解質膜を透過して空気極（カソード）側に移動する。酸化剤ガス流路から空気極（カソード）に供給される酸素は、移動してきた水素イオンと反応し、水を生成する。この発電反応により起電力が発生する。生成する水は、電解質膜に適度な湿度を与え、余剰の水分は拡散層を透過して、酸化剤ガス流路または燃料ガス流路から排出される。   In the fuel electrode (anode), hydrogen supplied from the fuel gas flow path through the diffusion layer is ionized by the catalytic action of the catalyst layer, passes through the electrolyte membrane, and moves to the air electrode (cathode) side. Oxygen supplied from the oxidant gas channel to the air electrode (cathode) reacts with the moving hydrogen ions to generate water. An electromotive force is generated by this power generation reaction. The generated water gives an appropriate humidity to the electrolyte membrane, and excess water passes through the diffusion layer and is discharged from the oxidant gas channel or the fuel gas channel.

このように燃料電池では発電の際に水を生成することから、燃料電池内に水が残留しやすく、氷点以下の低温環境下で凍結する問題がある。この対策として、運転停止時に燃料電池内を掃気して、残留水を掃気ガスとともに外部へ排出することが行われている。ただし、掃気により残留水を排出しても、低温環境下での運転開始時に過冷却状態で発生する生成水が凍結を引き起こすことがある。そして、凍結が伝播して急激に発電性能が低下すると、始動に必要な発熱量が得られなくおそれがあり、氷点下での始動性向上が大きな課題となっている。   As described above, in the fuel cell, water is generated during power generation. Therefore, there is a problem that water tends to remain in the fuel cell and freezes in a low temperature environment below the freezing point. As a countermeasure, the inside of the fuel cell is scavenged when the operation is stopped, and the residual water is discharged to the outside together with the scavenging gas. However, even if residual water is discharged by scavenging, the generated water generated in a supercooled state at the start of operation in a low temperature environment may cause freezing. And if freezing propagates and power generation performance falls rapidly, there is a possibility that the calorific value required for start-up may not be obtained, and improvement of startability below freezing is a major issue.

従来技術としては、例えば、特許文献１に記載されるように、氷点下で燃料電池を始動する際に燃料電池スタックの温度を上昇させて、凍結を防止する方法が提案されている。特許文献１の燃料電池は、例えば電気的な加熱手段を設けて冷却液流路を流通する冷却液を加熱し、燃料電池スタックの少なくとも一部の領域を昇温させるものである。
特開２０００−５１２０６８号公報 As a prior art, for example, as described in Patent Document 1, a method for preventing freezing by increasing the temperature of the fuel cell stack when starting the fuel cell below freezing point has been proposed. In the fuel cell of Patent Document 1, for example, an electrical heating means is provided to heat the coolant flowing through the coolant flow path and to raise the temperature of at least a part of the fuel cell stack.
JP 2000-512068 A

また、例えば、特許文献２、３に記載されるように、膜電極接合体に撥水性を付与して、排水を促進する構成とした燃料電池がある。特許文献２の固体電解質膜は、ガス拡散基材の表面に撥水層を有しており、さらにその一部に水の浸透経路を形成することで、排水性を向上させ、その他の部位をガス拡散経路とするようになっている。また、特許文献３には、固体電解質膜の両面に形成した触媒層上に、撥水性領域と親水性領域を有するガスまたは液体の透過層を形成して、必要な撥水性と親水性とを兼備させることが提案されている。
特開２００６−１７９３１７号公報 特開２００５−２１６７５０号公報 Further, for example, as described in Patent Documents 2 and 3, there is a fuel cell configured to promote drainage by imparting water repellency to a membrane electrode assembly. The solid electrolyte membrane of Patent Document 2 has a water-repellent layer on the surface of the gas diffusion base material, and further improves the drainage by forming a water permeation path in a part of the water-repellent layer. It is designed to be a gas diffusion path. In Patent Document 3, a gas or liquid permeable layer having a water-repellent region and a hydrophilic region is formed on a catalyst layer formed on both surfaces of a solid electrolyte membrane, so that necessary water repellency and hydrophilicity are obtained. It has been proposed to combine them.
JP 2006-179317 A JP 2005-216750 A

しかしながら、特許文献１の方法では、燃料電池に電気的加熱手段を設ける必要があり、システム構成が複雑となってコストアップ要因となる上、燃料電池の加熱に電力を使用するため、車両の燃料効率が著しく低下する。また、特許文献２の構成は、氷点下では水の浸透経路内にて水を凍結させて、ガス拡散経路を確保しようとしており、特許文献３の構成は、凍結防止を目的とするものではない。このため、これら従来の構成により生成水の凍結を防止することは難しく、また、一部で凍結が開始されると、凍結が伝播して急激な発電性能の低下を引き起こし、始動が困難になるおそれがあった。   However, in the method of Patent Document 1, it is necessary to provide an electric heating means for the fuel cell, which causes a complicated system configuration and increases the cost, and uses electric power for heating the fuel cell. Efficiency is significantly reduced. In addition, the configuration of Patent Document 2 attempts to secure a gas diffusion path by freezing water in the water permeation path below freezing point, and the structure of Patent Document 3 is not intended to prevent freezing. For this reason, it is difficult to prevent the generated water from being frozen by these conventional configurations, and when the freezing is partially started, the freezing propagates and causes a sudden decrease in power generation performance, which makes starting difficult. There was a fear.

本発明は上記問題点に鑑みてなされたものであり、燃料電池セル内で生成水の凍結が開始しても急激な発電性能の低下がなく、発電を継続させて発熱量を確保することで、システム構成部品を増加させることなく、氷点下始動が可能な燃料電池を提供することを目的とする。   The present invention has been made in view of the above problems, and even if freezing of generated water starts in the fuel battery cell, there is no sudden decrease in power generation performance, and the generation of heat is ensured by continuing power generation. An object of the present invention is to provide a fuel cell capable of starting below freezing without increasing system components.

上記課題を解決するための請求項１の発明は、酸化剤ガスと燃料ガスの化学反応により発電するセルを備える燃料電池であって、
上記セルは、電解質膜の両面に電極を配設した膜電極接合体の一方の面側に、酸化剤ガス流路を形成する酸化剤ガス側セパレータを配設するとともに、他方の面側に燃料ガス流路を形成する燃料ガス側セパレータを配設してなり、
上記電極は上記電解質膜に接する触媒層の外側に拡散層を有し、
上記拡散層には、少なくとも上記触媒層に接する表面に、強撥水層と弱撥水層とからなる撥水層を設けるとともに、上記強撥水層と上記弱撥水層とを、上記ガス流路のガス流れ方向に沿って交互に並列するように配置したものである。 The invention of claim 1 for solving the above-mentioned problem is a fuel cell comprising a cell that generates power by a chemical reaction between an oxidant gas and a fuel gas,
In the cell, an oxidant gas side separator that forms an oxidant gas flow path is disposed on one surface side of a membrane electrode assembly in which electrodes are disposed on both surfaces of an electrolyte membrane, and a fuel is disposed on the other surface side. A fuel gas side separator that forms a gas flow path is disposed,
The electrode has a diffusion layer outside the catalyst layer in contact with the electrolyte membrane,
The diffusion layer is provided with a water repellent layer composed of a strong water repellent layer and a weak water repellent layer on at least a surface in contact with the catalyst layer, and the strong water repellent layer and the weak water repellent layer are provided on the gas layer. They are arranged so as to be alternately arranged along the gas flow direction of the flow path.

氷点下での始動時に、触媒層と拡散層の界面において生成水が凍結すると、急激な発電低下を引き起こす。一般に、生成水の一部が凍結すると、連続した液水に凍結が急速に伝播するが、本発明の構成によれば、触媒層と拡散層の界面に介設した撥水層が、強撥水層と弱撥水層とからなるので、生成水が液滴となっても、ガス流れ方向に対しては、強撥水層にて液水が途切れる。よって、連続した液水となるのを防止し、凍結の伝播による急激な発電低下を防止することができるので、発電を継続して発熱量を確保し、燃料電池スタック全体を昇温することができる。   When the generated water freezes at the interface between the catalyst layer and the diffusion layer at the time of starting below freezing point, a rapid power generation decrease is caused. In general, when a part of the generated water freezes, the freezing rapidly propagates to the continuous liquid water. However, according to the configuration of the present invention, the water-repellent layer interposed between the catalyst layer and the diffusion layer is strongly repellent. Since it consists of a water layer and a weak water-repellent layer, even if the generated water becomes droplets, the liquid water is interrupted in the strong water-repellent layer in the gas flow direction. Therefore, it is possible to prevent continuous liquid water from being generated, and to prevent a sudden decrease in power generation due to the propagation of freezing. it can.

これにより、システム構成部品を増加させることなく、燃料電池の氷点下始動が可能となるので、コストが低減でき、発電性能の良好な燃料電池が実現できる。   As a result, the fuel cell can be started below the freezing point without increasing the number of system components, so that the cost can be reduced and a fuel cell with good power generation performance can be realized.

請求項２の発明のように、具体的には、上記撥水層は、撥水性の異なる２種類の撥水性材料よりなる。そして、該２種類の撥水性材料のうち相対的に撥水性の高い撥水性材料にて上記強撥水層を、相対的に撥水性の低い撥水性材料にて上記弱撥水層を構成したものである。   Specifically, the water repellent layer is made of two types of water repellent materials having different water repellency. The strong water-repellent layer is composed of a water-repellent material having a relatively high water repellency, and the weak water-repellent layer is composed of a water-repellent material having a relatively low water repellency. Is.

請求項３の発明のように、上記撥水層は、上記拡散層を構成する基材の上記触媒層側表面に、上記強撥水層となる撥水性材料と上記弱撥水層となる撥水性材料とを交互に塗布することにより形成される。あるいは上記触媒層側表面の全面に上記弱撥水層となる撥水性材料を塗布し、その表面の一部に上記強撥水層となる撥水性材料と含浸させることにより形成することができる。   According to a third aspect of the present invention, the water repellent layer has a water repellent material that becomes the strong water repellent layer and a water repellent layer that becomes the weak water repellent layer on the catalyst layer side surface of the base material constituting the diffusion layer. It is formed by alternately applying an aqueous material. Or it can form by apply | coating the water-repellent material used as the said weak water-repellent layer to the whole surface of the said catalyst layer side surface, and making it impregnate with the water-repellent material used as the said strong water-repellent layer in a part of the surface.

請求項４の発明において、上記酸化剤ガス側セパレータには上記酸化剤ガス流路となる複数の平行な溝が、上記燃料ガス側セパレータには上記燃料ガス流路となる複数の平行な溝が、それぞれ形成されており、上記強撥水層および上記弱撥水層を、上記ガス流路のガス流れと垂直な方向を長手方向とする短冊状に形成して、上記ガス流路となる複数の平行な溝を横切るように配置してある。   In the invention of claim 4, the oxidant gas side separator has a plurality of parallel grooves that serve as the oxidant gas flow path, and the fuel gas side separator has a plurality of parallel grooves that serve as the fuel gas flow path. A plurality of the strong water-repellent layer and the weakly water-repellent layer that are formed in a strip shape having a longitudinal direction in a direction perpendicular to the gas flow of the gas flow path. It is arranged so as to cross the parallel grooves.

好適には、酸化剤ガス側セパレータ、燃料ガス側セパレータに形成されるガス流路を横切るように、強撥水層および弱撥水層を形成すると、セパレータの面圧により、ガス流路と垂直な方向においても液水が途切れる効果が得られる。よって、液水の凍結が広範囲に伝播するのを防止する効果が高い。   Preferably, when the strong water-repellent layer and the weak water-repellent layer are formed so as to cross the gas flow path formed in the oxidant gas side separator and the fuel gas side separator, the surface pressure of the separator makes it perpendicular to the gas flow path. Even in any direction, the effect that the liquid water is interrupted can be obtained. Therefore, the effect of preventing the freezing of liquid water from spreading over a wide range is high.

請求項５の発明において、上記撥水層は、上記ガス流路のガス流れ方向における上記強撥水層の幅を２ｍｍ以上に形成してある。   In the invention of claim 5, the water-repellent layer is formed such that the width of the strong water-repellent layer in the gas flow direction of the gas flow path is 2 mm or more.

好適には、撥水層における強撥水層の幅を２ｍｍ以上に形成すると、液水を分断する効果を確実に得ることができる。   Preferably, when the width of the strong water-repellent layer in the water-repellent layer is 2 mm or more, the effect of dividing the liquid water can be obtained with certainty.

図１により、本発明を適用した燃料電池の第１実施形態を説明する。図１（ａ）は、燃料電池の主要部である燃料電池スタックＳのセルＣ構造を示す概略図であり、図１（ｂ）は、燃料電池スタックＳを含むシステム全体の概略構成図である。図１（ｂ）において、燃料電池スタックＳは、基本単位であるセルＣを多数積層して電気的に直列接続してなり、酸化剤ガスとなる空気の供給流路１０１・排出流路１０２、燃料ガスとなる水素の供給流路１０３・排出流路１０４や、各種制御装置等が接続されて燃料電池システムを構成している。   A first embodiment of a fuel cell to which the present invention is applied will be described with reference to FIG. FIG. 1A is a schematic diagram showing a cell C structure of a fuel cell stack S which is a main part of the fuel cell, and FIG. 1B is a schematic configuration diagram of the entire system including the fuel cell stack S. . In FIG. 1B, the fuel cell stack S is formed by laminating a number of cells C, which are basic units, and electrically connecting them in series. A fuel cell system is configured by connecting a supply channel 103 and a discharge channel 104 for hydrogen serving as a fuel gas, various control devices, and the like.

燃料電池スタックＳは、酸化剤ガスと燃料ガスの電気化学反応により発電を行い、ＤＣ／ＤＣコンバータにて電圧調整後、負荷の駆動に用いられる。コントローラはシステム全体を制御し、負荷（例えば燃料電池車両の駆動用モータや各種補機類）からの要求電力に応じて、燃料電池スタックＳへ供給される空気や水素の流量・圧力・湿度等を調整する。なお、図はシステム主要部を簡略化して示すもので、図示する以外にも冷却媒体流路等を設けたり、各流路にポンプやバルブといった通常公知のシステム構成部材を設けることができる。   The fuel cell stack S generates electric power by an electrochemical reaction between an oxidant gas and a fuel gas, and is used for driving a load after voltage adjustment by a DC / DC converter. The controller controls the entire system, and the flow rate, pressure, humidity, etc. of air or hydrogen supplied to the fuel cell stack S according to the required power from the load (for example, a drive motor and various auxiliary machines for a fuel cell vehicle) Adjust. In addition, the figure shows the system main part in a simplified manner. Besides the illustration, a cooling medium flow path or the like can be provided, and normally known system components such as a pump or a valve can be provided in each flow path.

図１（ａ）の左半図に示すように、燃料電池スタックＳの各セルＣは、電解質膜１１を挟んでその両面に電極がそれぞれ形成された膜電極接合体（ＭＥＡ：Membrane Electrode Assembly ）１を備え、このＭＥＡ１を挟んで一方の面側（図の右側）に酸化剤ガス側セパレータ４を、他方の面側（図の左側）に燃料ガス側セパレータ５を配設した構成となっている。本実施形態では、電解質膜１１の一方の表面に、電極となる触媒層２１と拡散層３１を、他方の面に触媒層２２と拡散層３２を、この順でそれぞれ配置して膜電極接合体を構成しており、酸化剤ガス側に設けた触媒層２１と拡散層３１とで、空気極（カソード）を、燃料ガス側に設けた触媒層２２と拡散層３２とで、燃料極（アノード）を形成している。   As shown in the left half of FIG. 1 (a), each cell C of the fuel cell stack S has a membrane electrode assembly (MEA) in which electrodes are formed on both sides of the electrolyte membrane 11, respectively. 1, an oxidant gas side separator 4 is disposed on one side (right side in the figure), and a fuel gas side separator 5 is disposed on the other side (left side in the figure) across the MEA 1. Yes. In the present embodiment, a catalyst layer 21 and a diffusion layer 31 serving as electrodes are arranged on one surface of the electrolyte membrane 11, and a catalyst layer 22 and a diffusion layer 32 are arranged in this order on the other surface, respectively. The catalyst layer 21 and the diffusion layer 31 provided on the oxidant gas side constitute an air electrode (cathode), and the catalyst layer 22 and the diffusion layer 32 provided on the fuel gas side constitute a fuel electrode (anode). ) Is formed.

酸化剤ガス側セパレータ４、燃料ガス側セパレータ５は、薄肉の導電性板材を波板状に成形したものからなる。この時、波板状の酸化剤ガス側セパレータ４には、図の左側または右側に開く多数の溝が、図の上下方向に交互に形成され、ＭＥＡ１側（図の左側）に開口する複数の溝と、対向する拡散層３１との間に、酸化剤ガス流路である空気流路４１が形成される。同様に、波板状の燃料ガス側セパレータ５の溝と、対向するＭＥＡ１の拡散層３２との間には、燃料ガス流路である水素流路５１が形成される。酸化剤ガス側セパレータ４、燃料ガス側セパレータ５の、拡散層３１、３２との当接面は集電部４２、５２として機能する。   The oxidant gas side separator 4 and the fuel gas side separator 5 are each formed by corrugating a thin conductive plate material. At this time, the corrugated oxidant gas side separator 4 is formed with a plurality of grooves that are alternately formed in the vertical direction in the figure and open to the MEA 1 side (left side in the figure). An air channel 41 that is an oxidant gas channel is formed between the groove and the opposing diffusion layer 31. Similarly, a hydrogen channel 51 which is a fuel gas channel is formed between the groove of the corrugated fuel gas side separator 5 and the diffusion layer 32 of the MEA 1 facing the corrugated plate. The contact surfaces of the oxidant gas side separator 4 and the fuel gas side separator 5 with the diffusion layers 31 and 32 function as current collectors 42 and 52.

空気流路４１は、互いに連通して一続きの流路となり、その一端側が入口部として図１（ｂ）の空気の供給流路１０１に、他端側が出口部として排出流路１０２に接続される。同様に水素流路５１も、互いに連通する流路を構成し、その一端側を入口部として図１（ｂ）の水素の供給流路１０３に、他端側を出口部として排出流路１０４に接続している。空気流路４１と空気流路４１の間の溝、または水素流路５１と水素流路５１の間の溝は、冷却水流路６となる。このような構成の単セルＣを積層することにより、図１（ｂ）の燃料電池スタックＳが構成される。   The air flow channel 41 communicates with each other to form a continuous flow channel, one end of which is connected to the air supply flow channel 101 of FIG. 1B as an inlet and the other end is connected to the discharge flow channel 102 as an outlet. The Similarly, the hydrogen flow path 51 also constitutes a flow path that communicates with each other, with one end side serving as an inlet portion in the hydrogen supply flow path 103 in FIG. 1B and the other end side serving as an outlet section in the discharge flow path 104. Connected. A groove between the air flow path 41 and the air flow path 41 or a groove between the hydrogen flow path 51 and the hydrogen flow path 51 becomes the cooling water flow path 6. By stacking the unit cells C having such a configuration, the fuel cell stack S of FIG. 1B is configured.

このようにセパレータ４、５を薄肉の板材で構成すると、セパレータ４、５が薄くなることで、セルＣの積層枚数に対して燃料電池スタックＳをコンパクトにすることができる。セパレータ４、５を厚肉の導電性板材とし、空気流路４１または水素流路５１となる溝を形成した構成とすることも、もちろんできる。   When the separators 4 and 5 are formed of thin plate materials in this way, the fuel cells stack S can be made compact with respect to the number of stacked cells C because the separators 4 and 5 are thinned. Of course, the separators 4 and 5 can be made of thick conductive plates, and the air flow channel 41 or the hydrogen flow channel 51 can be formed.

電解質膜１１には、公知の水素イオン伝導性固体高分子電解質膜、例えば、Ｎａｆｉｏｎ（デュポン社製：登録商標）等のパーフルオロスルホン系ポリマーを膜状に成形したものが好適に使用される。触媒層２１、２２は、白金触媒等の触媒を導電性の良好な材料、例えばカーボン粒子等に担持させ、電解質膜の材料等を用いてペースト状にしたものを、電解質膜１１の表面に層状に形成してなる。   As the electrolyte membrane 11, a known hydrogen ion conductive solid polymer electrolyte membrane, for example, a perfluorosulfone-based polymer such as Nafion (manufactured by DuPont: registered trademark) is preferably used. The catalyst layers 21 and 22 are formed by forming a catalyst, such as a platinum catalyst, on a material having good conductivity, such as carbon particles, and pasting the electrolyte membrane material or the like into a layer on the surface of the electrolyte membrane 11. Formed.

拡散層３１、３２の基材は、導電性およびガス拡散性の良好な材料、例えばカーボン繊維やカーボン粒子等の材料を用いて多孔質に形成され、空気流路４１または水素流路５１から供給される空気または水素を触媒層２１、２２へ良好に拡散させるものであればよい。拡散層３１、３２には、それぞれ触媒層２１、２２に接する表面に、撥水層３が設けられる。撥水層３の構成は、本発明の特徴部分であり、以下に詳述する。   The base material of the diffusion layers 31 and 32 is made porous using a material having good conductivity and gas diffusibility, for example, a material such as carbon fiber or carbon particle, and is supplied from the air channel 41 or the hydrogen channel 51. What is necessary is just to make the air or hydrogen to be diffused well into the catalyst layers 21 and 22. The diffusion layers 31 and 32 are provided with the water repellent layer 3 on the surfaces in contact with the catalyst layers 21 and 22, respectively. The structure of the water repellent layer 3 is a characteristic part of the present invention, and will be described in detail below.

図１（ａ）の右半図に示すように、撥水層３は、強撥水層３ａと弱撥水層３ｂからなる。本発明では、強撥水層３ａと弱撥水層３ｂとが、空気または水素の流れ方向において交互に並列するように形成することで、生成水の凍結が伝播するのを防止する。図は、酸化剤ガス側セパレータ４に接する拡散層３１表面の撥水層３を示したもので、酸化剤ガス側セパレータ４には、図の上下方向に複数の空気流路４１が平行に形成されている。これら空気流路４１は、図の左右方向を流れ方向としている。これに対し、撥水層３の強撥水層３ａと弱撥水層３ｂは、いずれも空気流路４１の流れ方向と垂直な方向を長手方向とする略一定幅の短冊状であり、空気流路４１の流れ方向に対して交互に並ぶストライプ状に配置されている。また、強撥水層３ａと弱撥水層３ｂとは、それぞれ複数の空気流路４１を横切って、上下方向に延びている。   As shown in the right half view of FIG. 1A, the water repellent layer 3 includes a strong water repellent layer 3a and a weak water repellent layer 3b. In the present invention, the strong water repellent layer 3a and the weak water repellent layer 3b are formed so as to be alternately arranged in parallel in the flow direction of air or hydrogen, thereby preventing the freezing of the generated water from propagating. The figure shows the water-repellent layer 3 on the surface of the diffusion layer 31 in contact with the oxidant gas side separator 4. The oxidant gas side separator 4 has a plurality of air flow paths 41 formed in parallel in the vertical direction of the figure. Has been. These air flow paths 41 have a flow direction in the left-right direction in the figure. On the other hand, the strong water-repellent layer 3a and the weakly water-repellent layer 3b of the water-repellent layer 3 are both strips having a substantially constant width with the direction perpendicular to the flow direction of the air flow path 41 as the longitudinal direction. They are arranged in stripes alternately arranged in the flow direction of the flow path 41. The strong water-repellent layer 3a and the weakly water-repellent layer 3b extend in the vertical direction across the plurality of air flow paths 41, respectively.

また、燃料ガス側セパレータ５に接する拡散層３２表面の撥水層３も、同様の構成となっている。すなわち、撥水層３の強撥水層３ａと弱撥水層３ｂは、いずれも水素流路５１の流れ方向と垂直な方向を長手方向とする略一定幅の短冊状で、水素流路５１の流れ方向に対して交互に並ぶストライプ状に配置される。また、強撥水層３ａと弱撥水層３ｂとは、それぞれ複数の水素流路５１を横切るように、上下方向に延びている。   Further, the water repellent layer 3 on the surface of the diffusion layer 32 in contact with the fuel gas side separator 5 has the same configuration. In other words, the strong water-repellent layer 3 a and the weakly water-repellent layer 3 b of the water-repellent layer 3 are both strips having a substantially constant width with the direction perpendicular to the flow direction of the hydrogen channel 51 as the longitudinal direction. Are arranged in stripes alternately arranged in the flow direction. The strong water-repellent layer 3 a and the weak water-repellent layer 3 b extend in the vertical direction so as to cross the plurality of hydrogen flow paths 51.

ここで、強撥水層３ａと弱撥水層３ｂとは、撥水性が異なる２種類の撥水性材料を組み合わせ、撥水性が相対的に高い方の材料にて強撥水層３ａを、撥水性が相対的に低い方の材料にて弱撥水層３ｂを形成している。撥水性の有無は、一般に、水との接触角度によって定義され、通常、撥水層表面に付着させた水滴との接触角度が９０°より大きい材料を、撥水性材料という。撥水性の強弱は、水との接触角度の大きさによって表され、接触角度が９０°を超えて大きくなるほど撥水性が強く、接触角度が９０°に近いほど撥水性が弱いといえる。   Here, the strong water-repellent layer 3a and the weak water-repellent layer 3b combine two types of water-repellent materials having different water repellency, and the strong water-repellent layer 3a is made of a material having a relatively high water repellency. The weak water-repellent layer 3b is formed of a material having a relatively low aqueous property. The presence or absence of water repellency is generally defined by the contact angle with water. Usually, a material having a contact angle with water droplets attached to the surface of the water repellent layer of more than 90 ° is referred to as a water repellant material. The strength of water repellency is expressed by the size of the contact angle with water. The greater the contact angle exceeds 90 °, the stronger the water repellency, and the closer the contact angle is to 90 °, the weaker the water repellency.

撥水性材料としては、撥水性を有する種々の撥水性材料を用いることができ、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＦＤ）等のフッ素樹脂系撥水材が、好適に使用される。これら撥水性材料は、通常、カーボン粒子および溶剤とともに混合したものを、塗布することにより撥水層３を容易に形成することができる。撥水性材料の複数種類を、所望の撥水性が得られるように、適宜、組み合わせて使用することもできる。また、撥水性材料にカーボン粒子を混合し、その配合割合を変更することで、強撥水層３ａと弱撥水層３ｂをつくり分けるようにしてもよい。   As the water repellent material, various water repellent materials having water repellency can be used. For example, fluororesin water repellent materials such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVFD) are preferably used. Is done. These water repellent materials can be easily formed with the water repellent layer 3 by applying a mixture of carbon particles and a solvent. A plurality of types of water repellent materials can be used in appropriate combination so that a desired water repellency can be obtained. Alternatively, the strong water-repellent layer 3a and the weakly water-repellent layer 3b may be separately formed by mixing carbon particles in the water-repellent material and changing the blending ratio thereof.

強撥水層３ａと弱撥水層３ｂは、撥水性にある程度の差があることが必要で、差が小さいと境界部における液水分断の効果が得にくい。通常は、強撥水層３ａとなる撥水材と、弱撥水層３ｂとなる撥水材の、水との接触角度の差Δθが、例えば５°以上とするのがよく、好適には、接触角度の差Δθを１０°以上とすることで、液水を分断する効果が得やすい。これにより、液水が連続した状態で存在するのを防止して、凍結が伝播しにくい構造とすることができる。   The strong water-repellent layer 3a and the weak water-repellent layer 3b are required to have a certain difference in water repellency, and if the difference is small, it is difficult to obtain the effect of liquid moisture interruption at the boundary. Usually, the difference Δθ in contact angle between the water-repellent material to be the strong water-repellent layer 3a and the water-repellent material to be the weakly water-repellent layer 3b with water is preferably 5 ° or more, and preferably When the contact angle difference Δθ is 10 ° or more, it is easy to obtain the effect of dividing the liquid water. As a result, it is possible to prevent liquid water from existing in a continuous state and to prevent freezing from propagating.

図２、３は、撥水層３を設けた拡散層３１（３２）の構成例を示すものである。図２は、撥水層３を塗り分け法により形成した場合であり、拡散層基材３３の表面には、強撥水層３ａと弱撥水層３ｂが、図の左右方向に交互に配置されている。この撥水層３を形成するには、強撥水層３ａの構成材料と弱撥水層３ｂの構成材料とを、拡散層基材３３の表面に、それぞれ所定の幅で、交互に塗布することを繰り返し行う。この場合、強撥水層３ａと弱撥水層３ｂの厚さは同じになる。   2 and 3 show a configuration example of the diffusion layer 31 (32) provided with the water repellent layer 3. FIG. FIG. 2 shows a case where the water-repellent layer 3 is formed by a separate coating method, and a strong water-repellent layer 3a and a weakly water-repellent layer 3b are alternately arranged on the surface of the diffusion layer base material 33 in the left-right direction of the figure. Has been. In order to form this water-repellent layer 3, the constituent material of the strong water-repellent layer 3a and the constituent material of the weakly water-repellent layer 3b are alternately applied to the surface of the diffusion layer base material 33 with a predetermined width, respectively. Repeat that. In this case, the strong water-repellent layer 3a and the weak water-repellent layer 3b have the same thickness.

図３は、拡散層基材３３表面に、撥水層３を含浸法により形成した場合であり、拡散層基材３３の表面には、全面を覆って弱撥水層３ｂが形成され、さらに弱撥水層３ｂの表面の一部に、強撥水層３ａが所定の間隔をおいてストライプ状に形成されている。この撥水層３を形成するには、まず、弱撥水層３ｂの構成材料を拡散層基材３３の表面全面に塗布形成し、その表面の所定位置に、強撥水層３ａの構成材料を上塗りして、含浸させる。この場合、強撥水層３ａの厚さは、弱撥水層３ｂより薄く、その上部表面のみに強撥水層３ａが形成されることになる。   FIG. 3 shows a case where the water-repellent layer 3 is formed on the surface of the diffusion layer base material 33 by an impregnation method, and the surface of the diffusion layer base material 33 is formed with a weak water-repellent layer 3b covering the entire surface. The strong water repellent layer 3a is formed in a stripe shape at a predetermined interval on a part of the surface of the weak water repellent layer 3b. In order to form the water repellent layer 3, first, the constituent material of the weak water repellent layer 3b is applied and formed on the entire surface of the diffusion layer substrate 33, and the constituent material of the strong water repellent layer 3a is formed at a predetermined position on the surface. Overcoat and impregnate. In this case, the strong water repellent layer 3a is thinner than the weak water repellent layer 3b, and the strong water repellent layer 3a is formed only on the upper surface thereof.

拡散層３１、３２を構成する拡散層基材３３や撥水層３の厚さは、任意に設定することができる。通常は、拡散層基材３３の厚さを、例えば１００μｍ以上、撥水層３の厚さを、例えば５０μｍ以上とするのがよい。撥水層３となる強撥水層３ａと弱撥水層３ｂの形成幅も、特に制限されず、例えば、強撥水層３ａの幅が、２ｍｍ程度ないしそれ以上あれば、分断効果が認められる。好適には、強撥水層３ａの幅を、所望の液水の分断効果が得られるように、適宜設定し、弱撥水層３ｂの幅をこれよりも広くして、撥水層３の全体に適度な撥水性を付与する構成とすればよい。図３のように含浸法による構成において、撥水層３の表面に強撥水層３ａが薄く形成した場合には、強撥水層３ａを、例えば５μｍ程度ないしそれ以上の厚さとすることで、強撥水層３ａによる液水の分断効果を得ることができる。   The thickness of the diffusion layer base material 33 and the water repellent layer 3 constituting the diffusion layers 31 and 32 can be arbitrarily set. Usually, it is preferable that the thickness of the diffusion layer base material 33 is, for example, 100 μm or more, and the thickness of the water repellent layer 3 is, for example, 50 μm or more. The formation width of the strong water-repellent layer 3a and the weakly water-repellent layer 3b to be the water-repellent layer 3 is also not particularly limited. For example, if the width of the strong water-repellent layer 3a is about 2 mm or more, the separation effect is recognized It is done. Preferably, the width of the strong water-repellent layer 3a is appropriately set so as to obtain a desired liquid water dividing effect, and the width of the weakly water-repellent layer 3b is made wider than this, What is necessary is just to set it as the structure which provides moderate water repellency to the whole. When the strong water-repellent layer 3a is thinly formed on the surface of the water-repellent layer 3 in the impregnation method as shown in FIG. 3, the strong water-repellent layer 3a has a thickness of, for example, about 5 μm or more. In addition, the effect of dividing liquid water by the strong water-repellent layer 3a can be obtained.

上記構成の燃料電池の作動について図１（ａ）、（ｂ）により説明する。
空気の供給流路１０１および水素の供給流路１０３から、燃料電池スタックＳに空気および水素が供給されると、各セルＣ内の空気流路４１に空気が、水素流路５１に水素が導入され、ＭＥＡ１の両電極において下記の電気化学反応が起こる。
水素極（アノード） Ｈ2 →２Ｈ+ ＋２ｅ- ・・・（１）
空気極（カソード） ２Ｈ+ ＋１／２Ｏ2 + ＋２ｅ- →Ｈ2 Ｏ・・・（２）
反応に用いられなかった未反応空気は排出流路１０２から排出される。未反応水素は排出流路１０４から排出され、循環再利用される。 The operation of the fuel cell configured as described above will be described with reference to FIGS. 1 (a) and 1 (b).
When air and hydrogen are supplied to the fuel cell stack S from the air supply channel 101 and the hydrogen supply channel 103, air is introduced into the air channel 41 in each cell C, and hydrogen is introduced into the hydrogen channel 51. Then, the following electrochemical reaction occurs at both electrodes of MEA1.
Hydrogen electrode (anode) H 2 → 2H + + 2e − (1)
Air electrode (cathode) 2H + + 1 / 2O 2 + + 2e − → H 2 O (2)
Unreacted air that has not been used for the reaction is discharged from the discharge channel 102. Unreacted hydrogen is discharged from the discharge channel 104 and recycled.

ここで、上記式（２）のように、各セルＣの空気流路４１側では、発電の際に水素と酸素が反応して水が生成する。この水分は、触媒層２１から拡散層３１内を拡散して空気流路４１へ排出される一方、電解質膜１１を透過して水素流路５１側へ移動し、触媒層２２から拡散層３２内を拡散して水素流路５１へ排出される。この時、電解質膜１１の近傍で生成する水分を速やかに排出するために、拡散層３１、３２の触媒層２１、２２との界面に撥水層３が設けられ、生成水の液水化を抑制し排出を促す。ただし、氷点以下の低温環境下での始動時には、過冷却状態で上記発電反応による水が生成することになり、この水が、触媒層２１、２２または拡散層３１、３２内で凍結すると、ガス拡散が阻害されるために、上記発電反応が良好に進行しなくなる。その結果、発熱量が不十分となって燃料電池スタックＳが発電に適当な温度（通常、６０〜１００℃程度）まで上昇せず、自己発熱による始動が困難となる。   Here, as in the above formula (2), on the air flow path 41 side of each cell C, hydrogen and oxygen react to generate water during power generation. The moisture diffuses from the catalyst layer 21 through the diffusion layer 31 and is discharged to the air flow path 41, while passing through the electrolyte membrane 11 and moves toward the hydrogen flow path 51, and from the catalyst layer 22 to the diffusion layer 32. Is diffused and discharged to the hydrogen flow path 51. At this time, a water repellent layer 3 is provided at the interface between the diffusion layers 31 and 32 and the catalyst layers 21 and 22 in order to quickly discharge the water generated in the vicinity of the electrolyte membrane 11, thereby liquefying the generated water. Suppress and promote emissions. However, at the time of starting in a low temperature environment below the freezing point, water due to the power generation reaction is generated in a supercooled state, and when this water is frozen in the catalyst layers 21 and 22 or the diffusion layers 31 and 32, the gas Since the diffusion is inhibited, the power generation reaction does not proceed well. As a result, the amount of heat generation becomes insufficient, and the fuel cell stack S does not rise to a temperature suitable for power generation (usually about 60 to 100 ° C.), making it difficult to start by self-heating.

本発明者等の実験によれば、氷点下での始動時に、触媒層２１、２２と拡散層３１、３２との界面において生成水が凍結すると、急激な発電低下を引き起こすことがわかっている。また、一般に、生成水の一部が凍結すると、連続した液水に凍結が伝播する。つまり、従来の構成において生じる急激な発電低下は、触媒層２１、２２と拡散層３１、３２との界面において、生成水が液水となって溜まりやすい状態であることを意味する。そこで、本発明では、上述したように、撥水層３を強撥水層３ａと弱撥水層３ｂとで構成し、連続した液水が存在する状態を解消して、凍結の伝播を防止しようとするものである。   According to the experiments by the present inventors, it is known that if the generated water freezes at the interface between the catalyst layers 21 and 22 and the diffusion layers 31 and 32 at the time of starting below freezing point, the power generation is drastically reduced. In general, when a part of the generated water freezes, the freezing propagates to the continuous liquid water. That is, the rapid power generation drop that occurs in the conventional configuration means that the generated water is liable to accumulate as liquid water at the interface between the catalyst layers 21 and 22 and the diffusion layers 31 and 32. Therefore, in the present invention, as described above, the water-repellent layer 3 is composed of the strong water-repellent layer 3a and the weakly water-repellent layer 3b, and the state where continuous liquid water exists is eliminated to prevent freezing propagation. It is something to try.

すなわち、図１（ａ）の右半部に示すように、本発明の拡散層３１、３２では、触媒層２１、２２と接する撥水層３が、空気流路４１または水素流路５１のガス流れ方向に沿って、強撥水層３ａと弱撥水層３ｂとが交互に現れるようにしてある。このため、触媒層２１、２２と拡散層３１、３２との界面で、生成水が液滴となっても、ガス流れ方向に対しては、強撥水層３ａにて液水が途切れる。また、ガス流れと垂直な方向には、酸化剤ガス側セパレータ４の空気流路４１間に形成される集電部４２、燃料ガス側セパレータ５の水素流路５１に形成される集電部５２が、拡散層３１、３２に当接しており、その面圧によって、触媒層２１、２２と拡散層３１、３２の界面の液水が途切れる。   That is, as shown in the right half of FIG. 1A, in the diffusion layers 31 and 32 of the present invention, the water-repellent layer 3 in contact with the catalyst layers 21 and 22 is the gas in the air channel 41 or the hydrogen channel 51. The strong water-repellent layer 3a and the weak water-repellent layer 3b appear alternately along the flow direction. For this reason, even if the generated water becomes droplets at the interfaces between the catalyst layers 21 and 22 and the diffusion layers 31 and 32, the liquid water is interrupted by the strong water-repellent layer 3a in the gas flow direction. Further, in a direction perpendicular to the gas flow, a current collecting part 42 formed between the air flow paths 41 of the oxidant gas side separator 4 and a current collecting part 52 formed in the hydrogen flow path 51 of the fuel gas side separator 5. However, the liquid water at the interface between the catalyst layers 21 and 22 and the diffusion layers 31 and 32 is interrupted by the surface pressure.

これらにより、連続する液水となることが防止され、氷点下始動時に、触媒層２１、２２と拡散層３１、３２との界面で凍結が伝播しようとしても、液水が途切れているために、凍結が広範囲に広がることがない。したがって、発電反応に伴う発熱量を確保することができるので、自己発熱による氷点下からの始動が可能となる。   As a result, the liquid water is prevented from becoming continuous, and even when freezing is propagated at the interface between the catalyst layers 21 and 22 and the diffusion layers 31 and 32 at the time of starting below the freezing point, the liquid water is interrupted. Does not spread over a wide area. Therefore, the amount of heat generated by the power generation reaction can be ensured, so that starting from below freezing by self-heating is possible.

（実施例１）
次に、本発明の効果を確認するために、上記図２に示す構造の拡散層３１のサンプルを作成した。拡散層３１の基材３３としては、３６×３６ｍｍの正方形のカーボンペーパ（東レ（株）製：ＴＧＰＨ０６０；厚さ １９０μｍ）を使用し、その表面に、幅１０．５ｍｍの弱撥水層３ｂ、幅２ｍｍの強撥水層３ａ、幅１１．０ｍｍの弱撥水層３ｂ、幅２ｍｍの強撥水層３ａ、幅１０．５ｍｍの弱撥水層３ｂを、交互に形成して撥水層３とした。強撥水層３ａ、弱撥水層３ｂの厚さは、１５０μｍ程度とした。強撥水層３ａ、弱撥水層３ｂの構成材料には、いずれもポリテトラフルオロエチレン（ＰＴＦＥ）系の撥水性の異なる材料を使用し、強撥水層３ａには水との接触角度が１５５°程度の撥水材を、弱撥水層３ｂには水との接触角度が１４５°程度の撥水材を用いた。この撥水材にカーボン粒子と溶剤を添加混合して得た混合物を、基材３３に塗布して、撥水層３を形成した。 Example 1
Next, in order to confirm the effect of the present invention, a sample of the diffusion layer 31 having the structure shown in FIG. 2 was prepared. As the base material 33 of the diffusion layer 31, a 36 × 36 mm square carbon paper (manufactured by Toray Industries, Inc .: TGPH060; thickness 190 μm) is used, and on its surface, a weak water repellent layer 3b having a width of 10.5 mm, A water repellent layer 3a having a width of 2 mm, a weak water repellent layer 3b having a width of 11.0 mm, a strong water repellent layer 3a having a width of 2 mm, and a weak water repellent layer 3b having a width of 10.5 mm are alternately formed. It was. The thickness of the strong water repellent layer 3a and the weak water repellent layer 3b was about 150 μm. As materials for the strong water-repellent layer 3a and the weak water-repellent layer 3b, polytetrafluoroethylene (PTFE) materials having different water repellency are used, and the strong water-repellent layer 3a has a contact angle with water. A water repellent material of about 155 ° was used, and a water repellent material having a contact angle with water of about 145 ° was used for the weak water repellent layer 3b. A mixture obtained by adding and mixing carbon particles and a solvent to the water repellent material was applied to the substrate 33 to form the water repellent layer 3.

得られたサンプルの撥水層３表面に、水を滴下して、その上からプレパラートを覆着する評価試験を実施したところ、強撥水層３ａにおいて水が分断されたことが確認された。なお、比較のために、強撥水層３ａの幅を２ｍｍとした以外は、同様の方法でサンプルを形成したところ、水の分断をはっきりと確認することができなかった。   When an evaluation test was performed in which water was dropped onto the surface of the water-repellent layer 3 of the obtained sample and the preparation was covered from above, it was confirmed that water was divided in the strong water-repellent layer 3a. For comparison, when the sample was formed by the same method except that the width of the strong water-repellent layer 3a was set to 2 mm, it was not possible to clearly confirm the division of water.

（実施例２）
上記図３に示す構造の拡散層３１のサンプルを作成した。拡散層３１の基材３３としては、３６×３６ｍｍの正方形のカーボンペーパ（東レ（株）製：ＴＧＰＨ０６０；厚さ１９０μｍ）を使用し、その表面の全面に弱撥水層３ｂを形成した（厚さ１５０μｍ程度）。弱撥水層３ｂには、ポリテトラフルオロエチレン（ＰＴＦＥ）系で水との接触角度が１４０°程度の撥水材を用い、撥水材とカーボン粒子と溶剤で混合してから、基材３３に塗布した。その後、加熱して弱撥水層３ｂとし、その上面に、強撥水層３ａ（幅２ｍｍ、厚さ５μｍ程度）を、９ｍｍピッチでストライプ状に形成した。強撥水層３ａには、ポリテトラフルオロエチレン（ＰＴＦＥ）系で水との接触角度が１５５°程度の撥水材を用い、カーボン粒子と溶剤で混合したものを塗布した。 (Example 2)
A sample of the diffusion layer 31 having the structure shown in FIG. 3 was prepared. As the base material 33 of the diffusion layer 31, a 36 × 36 mm square carbon paper (manufactured by Toray Industries, Inc .: TGPH060; thickness 190 μm) was used, and a weak water-repellent layer 3b was formed on the entire surface (thickness). About 150 μm). For the weak water repellent layer 3b, a polytetrafluoroethylene (PTFE) water repellent material having a contact angle with water of about 140 ° is used, mixed with the water repellent material, the carbon particles, and the solvent, and then the base material 33 It was applied to. Then, it was heated to form a weak water-repellent layer 3b, and a strong water-repellent layer 3a (width 2 mm, thickness about 5 μm) was formed in a stripe shape at a pitch of 9 mm on its upper surface. The strong water-repellent layer 3a was a polytetrafluoroethylene (PTFE) -based water-repellent material having a contact angle with water of about 155 °, and a mixture of carbon particles and a solvent was applied.

得られたサンプルに、上記実施例１と同様の評価試験を実施した。撥水層３表面に水を滴下して、その上からプレパラートを覆着して観察したところ、強撥水層３ａにおいて水が分断されたことが確認された。   The same evaluation test as in Example 1 was performed on the obtained sample. When water was dropped on the surface of the water repellent layer 3 and a preparation was covered from above, observation was made and it was confirmed that water was divided in the strong water repellent layer 3a.

以上のように、本発明によれば、加熱手段を設けたり流路構成やシステムを大きく変更することなく、良好な掃気性を有して、残留水が起点となる凍結を防止できる燃料電池のセル構成を実現することができる。
本実施形態の構成によれば、酸化剤ガス側セパレータ３に対向する拡散層２１の表面に、通気性が高い導電性通気層８を形成して通気性を向上させたので、掃気処理時に、拡散層２１と集電用リブ３１との間に掃気ガスが容易に流通する。これにより、残留する水分が掃気ガスによって持ちさられやすくなり、乾燥が促進される。よって、氷点下での運転開始時に残留水の凍結が起点となって、過冷却状態で生成した水分が凍結するのを防止することができる。なお、少なくとも集電用リブ３１との当接部位において拡散層２１の表面に導電性通気層８を介設する構成とすれば、集電用リブ３１下の通気性を向上させて排水を促進させる効果が得られる。 As described above, according to the present invention, there is provided a fuel cell that has good scavenging properties and can prevent freezing starting from residual water without providing heating means or greatly changing the flow path configuration or system. A cell configuration can be realized.
According to the configuration of the present embodiment, the air permeability is improved by forming the highly conductive air-permeable layer 8 on the surface of the diffusion layer 21 facing the oxidant gas-side separator 3. A scavenging gas easily flows between the diffusion layer 21 and the current collecting rib 31. Thereby, the remaining moisture is easily held by the scavenging gas, and drying is promoted. Therefore, it is possible to prevent the water generated in the supercooled state from freezing due to the freezing of the residual water at the start of operation below freezing. If the conductive ventilation layer 8 is provided on the surface of the diffusion layer 21 at least at the contact portion with the current collecting rib 31, the air permeability under the current collecting rib 31 is improved to promote drainage. Effect is obtained.

以上のように、本発明によれば、加熱手段を設けたり、システム構成部品を増加させることなく、氷点下始動時に生成水が凍結することによる急激な発電性能の低下を防止し、自己発熱による氷点下始動を可能にすることができる。   As described above, according to the present invention, it is possible to prevent a sudden decrease in power generation performance due to freezing of generated water at the time of starting below freezing without providing heating means or increasing the number of system components. Start can be allowed.

以上、本発明の好ましい実施形態について説明したが、本発明が適用される燃料電池システムは、上記図１の構成に限定されるものではなく、燃料電池スタックＳの各部構成その他を変更することも可能である。例えば、セパレータ４、５は波板にて構成したが、厚板に溝を形成することにより構成してもよい。   The preferred embodiment of the present invention has been described above. However, the fuel cell system to which the present invention is applied is not limited to the configuration shown in FIG. 1, and the configuration of each part of the fuel cell stack S may be changed. Is possible. For example, although the separators 4 and 5 are made of corrugated plates, they may be made by forming grooves in thick plates.

本発明の第１実施形態であり、（ａ）は、燃料電池スタックのセル構成を示す概略断面図、（ｂ）は、燃料電池システム全体の概略構成図である。BRIEF DESCRIPTION OF THE DRAWINGS It is 1st Embodiment of this invention, (a) is a schematic sectional drawing which shows the cell structure of a fuel cell stack, (b) is a schematic block diagram of the whole fuel cell system. 本発明における強撥水層と弱撥水層の形成方法の一例を説明するための模式的な図である。It is a schematic diagram for demonstrating an example of the formation method of a strong water-repellent layer and a weak water-repellent layer in this invention. 本発明における強撥水層と弱撥水層の形成方法の他の例を説明するための模式的な図である。It is a schematic diagram for demonstrating the other example of the formation method of the strong water-repellent layer and weak water-repellent layer in this invention.

符号の説明Explanation of symbols

Ｓ 燃料電池スタック
Ｃ セル
１ ＭＥＡ（膜電極接合体）
１１ 電解質膜
２１、２２ 触媒層
３ 撥水層
３ａ 強撥水層
３ｂ 弱撥水層
３１、３２ 拡散層
４ 酸化剤ガス側セパレータ
４１ 空気流路（酸化剤ガス流路）
５ 燃料ガス側セパレータ
５１ 水素流路（燃料ガス流路）
６ 冷却水流路 S Fuel cell stack C Cell 1 MEA (membrane electrode assembly)
11 Electrolyte membranes 21, 22 Catalyst layer 3 Water repellent layer 3a Strong water repellent layer 3b Weak water repellent layer 31, 32 Diffusion layer 4 Oxidant gas side separator 41 Air channel (oxidant gas channel)
5 Fuel gas side separator 51 Hydrogen flow path (fuel gas flow path)
6 Cooling water flow path

Claims (5)

酸化剤ガスと燃料ガスの化学反応により発電するセルを備える燃料電池であって、
上記セルは、電解質膜の両面に電極を配設した膜電極接合体の一方の面側に、酸化剤ガス流路を形成する酸化剤ガス側セパレータを配設するとともに、他方の面側に燃料ガス流路を形成する燃料ガス側セパレータを配設してなり、
上記電極は上記電解質膜に接する触媒層の外側に拡散層を有し、
上記拡散層には、少なくとも上記触媒層に接する表面に、強撥水層と弱撥水層とからなる撥水層を設けるとともに、上記強撥水層と上記弱撥水層とを、上記ガス流路のガス流れ方向に沿って交互に並列するように配置したことを特徴とする燃料電池。 A fuel cell comprising a cell that generates electricity by a chemical reaction between an oxidant gas and a fuel gas,
In the cell, an oxidant gas side separator that forms an oxidant gas flow path is disposed on one surface side of a membrane electrode assembly in which electrodes are disposed on both surfaces of an electrolyte membrane, and a fuel is disposed on the other surface side. A fuel gas side separator that forms a gas flow path is disposed,
The electrode has a diffusion layer outside the catalyst layer in contact with the electrolyte membrane,
The diffusion layer is provided with a water repellent layer composed of a strong water repellent layer and a weak water repellent layer on at least a surface in contact with the catalyst layer, and the strong water repellent layer and the weak water repellent layer are provided on the gas layer. A fuel cell, wherein the fuel cells are arranged alternately in parallel along a gas flow direction of a flow path. 上記撥水層は、撥水性の異なる２種類の撥水性材料よりなり、該２種類の撥水性材料のうち相対的に撥水性の高い撥水性材料にて上記強撥水層を、相対的に撥水性の低い撥水性材料にて上記弱撥水層を構成した請求項１記載の燃料電池。   The water-repellent layer is composed of two types of water-repellent materials having different water repellency. Of the two types of water-repellent materials, the strongly water-repellent layer is relatively The fuel cell according to claim 1, wherein the weak water-repellent layer is composed of a water-repellent material having low water repellency. 上記撥水層は、上記拡散層を構成する基材の上記触媒層側表面に、上記強撥水層となる撥水性材料と上記弱撥水層となる撥水性材料とを交互に塗布するか、あるいは上記触媒層側表面の全面に上記弱撥水層となる撥水性材料を塗布し、その表面の一部に上記強撥水層となる撥水性材料と含浸させることにより形成される請求項２記載の燃料電池。   Whether the water repellent layer is alternately applied with the water repellent material to be the strong water repellent layer and the water repellent material to be the weak water repellent layer on the surface of the catalyst layer side of the base material constituting the diffusion layer. Alternatively, it is formed by applying a water-repellent material that becomes the weak water-repellent layer to the entire surface of the catalyst layer side surface and impregnating a part of the surface with the water-repellent material that becomes the strong water-repellent layer. 2. The fuel cell according to 2. 上記酸化剤ガス側セパレータには上記酸化剤ガス流路となる複数の平行な溝が、上記燃料ガス側セパレータには上記燃料ガス流路となる複数の平行な溝が、それぞれ形成されており、上記強撥水層および上記弱撥水層を、上記ガス流路のガス流れと垂直な方向を長手方向とする短冊状に形成して、上記ガス流路となる複数の平行な溝を横切るように配置した請求項１ないし３のいずれか１項に記載の燃料電池。   The oxidant gas side separator is formed with a plurality of parallel grooves serving as the oxidant gas flow path, and the fuel gas side separator is formed with a plurality of parallel grooves serving as the fuel gas flow path, The strong water-repellent layer and the weak water-repellent layer are formed in a strip shape having a direction perpendicular to the gas flow of the gas flow path as a longitudinal direction so as to cross a plurality of parallel grooves serving as the gas flow paths. The fuel cell according to any one of claims 1 to 3, wherein the fuel cell is disposed in a position. 上記撥水層は、上記ガス流路のガス流れ方向における上記強撥水層の幅を２ｍｍ以上に形成した請求項１ないし４のいずれか１項に記載の燃料電池。   5. The fuel cell according to claim 1, wherein the water-repellent layer is formed such that a width of the strong water-repellent layer in the gas flow direction of the gas flow path is 2 mm or more.
JP2007110588A 2007-04-19 2007-04-19 Fuel cell Expired - Fee Related JP5036384B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2007110588A JP5036384B2 (en) 2007-04-19 2007-04-19 Fuel cell

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2007110588A JP5036384B2 (en) 2007-04-19 2007-04-19 Fuel cell

Publications (2)

Publication Number Publication Date
JP2008269929A true JP2008269929A (en) 2008-11-06
JP5036384B2 JP5036384B2 (en) 2012-09-26

Family

ID=40049180

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2007110588A Expired - Fee Related JP5036384B2 (en) 2007-04-19 2007-04-19 Fuel cell

Country Status (1)

Country Link
JP (1) JP5036384B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018105301A1 (en) * 2016-12-05 2018-06-14 東レ株式会社 Gas diffusion electrode and production method therefor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007042466A (en) * 2005-08-04 2007-02-15 Toyota Motor Corp Fuel cell

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007042466A (en) * 2005-08-04 2007-02-15 Toyota Motor Corp Fuel cell

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018105301A1 (en) * 2016-12-05 2018-06-14 東レ株式会社 Gas diffusion electrode and production method therefor
JPWO2018105301A1 (en) * 2016-12-05 2019-10-24 東レ株式会社 Gas diffusion electrode and manufacturing method thereof
US11283082B2 (en) 2016-12-05 2022-03-22 Toray Industries, Inc. Gas diffusion electrode and production method therefor

Also Published As

Publication number Publication date
JP5036384B2 (en) 2012-09-26

Similar Documents

Publication Publication Date Title
JP4312257B2 (en) Fuel cell
US20080113241A1 (en) Fuel cell microporous layer with microchannels
WO2011114702A1 (en) Polymer electrolyte fuel cell and fuel cell stack equipped with same
US20180248204A1 (en) Bipolar plate and a fuel cell stack comprising same
KR101223082B1 (en) Fuel cell
EP2367227A2 (en) A membrane electrode assembly for a fuel cell and a fuel cell stack incorporating the same
JP2010021053A (en) Fuel cell system
US20160049668A1 (en) Fuel cell with improved reactant distribution
JP2007103241A (en) Fuel cell
JP2011018525A (en) Fuel cell and fuel cell system
JP5310730B2 (en) Fuel cell
JP5036384B2 (en) Fuel cell
US7060383B2 (en) Fuel cell
JP5341321B2 (en) Electrolyte membrane / electrode structure for polymer electrolyte fuel cells
JP2009043688A (en) Fuel cell
JP2006147501A (en) Contact pressure adjusting device and method for fuel cell
JP2008146897A (en) Fuel cell separator, and fuel cell
JP2005317416A (en) Fuel battery and its manufacturing method
JP2009140795A (en) Fuel cell
JP2008198507A (en) Membrane electrode assembly, fuel cell, and catalyst ink
JP2005310586A (en) Fuel battery
JP2007299627A (en) Fuel cell and fuel cell system
KR20170063225A (en) Fuel cell stack
JP2006313663A (en) Fuel cell
JP2008010164A (en) Gas diffusion layer used for fuel cell, and the fuel cell

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20091001

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20120312

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20120321

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20120517

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20120605

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20120703

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20150713

Year of fee payment: 3

R150 Certificate of patent or registration of utility model

Ref document number: 5036384

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

LAPS Cancellation because of no payment of annual fees