JP5035571B2 - Current collecting structure for fuel cell and solid oxide fuel cell stack - Google Patents

Current collecting structure for fuel cell and solid oxide fuel cell stack Download PDF

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JP5035571B2
JP5035571B2 JP2009283904A JP2009283904A JP5035571B2 JP 5035571 B2 JP5035571 B2 JP 5035571B2 JP 2009283904 A JP2009283904 A JP 2009283904A JP 2009283904 A JP2009283904 A JP 2009283904A JP 5035571 B2 JP5035571 B2 JP 5035571B2
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fuel cell
current collecting
collecting structure
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protrusion
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JP2010092877A (en
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文紀 佐藤
圭子 櫛引
靖志 中島
重夫 井深
佳子 菱谷
格 柴田
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Nissan Motor Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • 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

Description

本発明は、平板型単セル間の通電を確実にし、温度変化等に起因する熱応力による変形等による通電特性の低下を防止した燃料電池用集電構造及び固体酸化物形燃料電池スタックに関する。   The present invention relates to a current collecting structure for a fuel cell and a solid oxide fuel cell stack in which energization between flat single cells is ensured and deterioration of energization characteristics due to deformation due to thermal stress caused by temperature change or the like is prevented.

最近、例えば空気と水素をそれぞれ、酸化剤ガスおよび燃料ガスとして、燃料が本来持っている化学エネルギーを直接電気エネルギーに変換する燃料電池が、省資源、環境保護の観点から注目されており、特に固体酸化物形燃料電池（ＳＯＦＣ）は発電効率が高く、廃熱を有効に利用できるなど多くの利点を有するため研究、開発が進んでいる。   Recently, for example, fuel cells that directly convert chemical energy inherent in fuel into electrical energy using air and hydrogen as oxidant gas and fuel gas, respectively, have attracted attention from the viewpoint of resource saving and environmental protection. Solid oxide fuel cells (SOFCs) have many advantages such as high power generation efficiency and effective use of waste heat, and research and development are progressing.

例えば、従来例として、図１に示すような、内部マニホールド方式の平板型固体電解質燃料電池１００がある。なお、「内部マニホールド方式」とは、固体電解質燃料電池に燃料ガスと酸化剤ガスとを供給するため、固体電解質燃料電池のセパレータ等にそれぞれのガスの給排気孔を設け、これらの孔から各平板型単電池の各電極面に各ガスを給排気するようにしたものを称している。
平板型固体電解質燃料電池１００は、イットリアなどをドープしたジルコニア焼結体（ＹＳＺ）からなる平板型固体電解質層１０２の両面に、それぞれ（Ｌａ、Ｓｒ）ＭｎＯ３の空気極１０４と、ＮｉＯ−ＹＳＺサーメットの燃料極１０６とを配置した平板型単電池１０８と、隣接する平板型単電池１０８同士を電気的に直列に接続し、且つ平板型単電池１０８に燃料ガスと酸化剤ガスとを分配するセパレータ１１０を有する。また、メッシュ状の金属１１５をセパレータ１１０と燃料極１０６との間に配置し、セパレータ１１０と空気極１０４との間に接続層１１７を配置し、セパレータ１１０と燃料極１０６及び空気極１０４とを導通させ、また、側面にシール材１１９を設け閉鎖させている。
そして、平板型固体電解質燃料電池１００を交互に積層し、通路１１４からそれぞれ酸化剤ガスと燃料ガスを導入し、各平板型単電池１０８の空気極１０４及び燃料極１０６の面にこれら酸化剤ガスと燃料ガスを接触させることにより起電力を発生させ、直列に積層した固体電解質燃料電池１００から出力するようにしている。 For example, as a conventional example, there is a flat solid electrolyte fuel cell 100 of an internal manifold type as shown in FIG. In addition, the “internal manifold system” means that in order to supply the fuel gas and the oxidant gas to the solid electrolyte fuel cell, each gas supply / exhaust hole is provided in the separator of the solid electrolyte fuel cell, and each of these holes is used to It refers to the gas supplied and exhausted to and from each electrode surface of the flat cell.
The flat solid electrolyte fuel cell 100 includes (La, Sr) MnO 3 air electrodes 104 and NiO-YSZ cermets on both sides of a flat solid electrolyte layer 102 made of a zirconia sintered body (YSZ) doped with yttria or the like. The flat plate unit cell 108 in which the fuel electrode 106 is disposed, and the adjacent flat unit cells 108 are electrically connected in series, and the separator for distributing the fuel gas and the oxidant gas to the plate unit cell 108. 110. Further, the mesh-like metal 115 is disposed between the separator 110 and the fuel electrode 106, the connection layer 117 is disposed between the separator 110 and the air electrode 104, and the separator 110, the fuel electrode 106, and the air electrode 104 are connected. In addition, a sealing material 119 is provided on the side surface and closed.
Then, the flat solid electrolyte fuel cells 100 are alternately stacked, and an oxidant gas and a fuel gas are respectively introduced from the passages 114. These oxidant gases are provided on the surfaces of the air electrode 104 and the fuel electrode 106 of each flat cell 108. The fuel gas is brought into contact with each other to generate an electromotive force, which is output from the solid electrolyte fuel cells 100 stacked in series.

しかし、従来から、セパレータ１１０の集電面は、機械加工等により平面に形成しているが、平板型単電池１０８は、製作時に生じた反りや歪みを有し、その歪みは平板型単電池１０８の材質等の関係から機械的な加工を行なって完全な平面に修正することが困難であった。そのため、セパレータ１１０を平板型単電池１０８に取り付けた場合、平板型単電池１０８がセパレータ１１０の集電面と面全体で接触するのではなく、多くとも３点の点接触となって良好な電気的な接続状態が得られないことがあった。
また、平板型単電池１０８を複数積層した際、締め付けの荷重がセラミック製のセパレータ１１０を介して平板型単電池１０８にかかる構造であり、温度変動により締め付け力が変化し荷重が過大になったときセパレータ１１０や平板型単電池１０８が破壊してしまうこともあった。更に、変形に対処するため平板型単電池１０８を電気的に接続させる導通用の金属１１５を強固にしなければならず、これによっても平板型単電池１０８に荷重がかかってしまい、熱応力等により平板型単電池１０８の破損等を引き起こすことが考えられる。このように、導電性セラミック等を用いたリジッドな集電方法では、スタックの熱分布による応力によりセルが破損するという問題点があった。 Conventionally, however, the current collecting surface of the separator 110 has been formed into a flat surface by machining or the like, but the flat cell 108 has warpage or distortion generated during manufacturing, and the distortion is flat plate cell. Due to the relationship between the material 108 and the like, it has been difficult to perform a mechanical processing to correct the surface completely. For this reason, when the separator 110 is attached to the flat cell 108, the flat cell 108 does not contact the current collecting surface of the separator 110 over the entire surface, but at most three points are in contact with each other. Connection state could not be obtained.
In addition, when a plurality of the flat unit cells 108 are stacked, the tightening load is applied to the flat unit cell 108 via the ceramic separator 110, and the tightening force changes due to temperature fluctuation, and the load becomes excessive. Sometimes the separator 110 and the flat cell 108 were destroyed. Further, in order to cope with the deformation, the conductive metal 115 for electrically connecting the flat cell 108 must be strengthened, and this also applies a load to the flat cell 108 due to thermal stress or the like. It is conceivable that the flat cell 108 is damaged. As described above, the rigid current collection method using a conductive ceramic or the like has a problem that the cell is damaged by the stress due to the heat distribution of the stack.

このような問題点を解決するため、例えば、凸部を持つ金属板を弾性的に空気極及び燃料極に接触させ、集電と同時にセルにかかる応力を緩和する燃料電池の集電構造が提案されている（特許文献１参照）。また、集電体として、導電性フェルトを用いる方法が提案されている（特許文献２参照）。更に、導電性フェルトを弾性接触により押し付けて設置することも提案されている（特許文献３参照）。   In order to solve such problems, for example, a current collecting structure for a fuel cell is proposed in which a metal plate having a convex portion is elastically brought into contact with the air electrode and the fuel electrode to relieve stress applied to the cell simultaneously with current collection. (See Patent Document 1). Further, a method using a conductive felt as a current collector has been proposed (see Patent Document 2). Furthermore, it has also been proposed to install conductive felt by pressing it with elastic contact (see Patent Document 3).

特開２００１−６８１３２号公報JP 2001-68132 A 特開平１−０１２４６９号公報JP-A-1-012469 特開平６−２０３８５７号公報JP-A-6-203857

しかし、特許文献１の技術は、セルが破損しないようその強度を確保するためセルを厚くする等の対策が必要となりスタックが重く、大きくなる。これでは、車両用として要求される軽い、小さいという要件に反する。
また、特許文献２の技術は、使用時に導電性フェルトの熱による緻密化が進行しクッション性の低下、変形による接触不良が発生する。車両用として用いると、振動、衝撃が激しくクッション性の低下、変形はより進行しやすい。
更に、特許文献３の技術は、弾性接触、即ち弾性体を挿入して導電性フェルトを押し付ける方法であるが、ＳＯＦＣの温度環境下で安定に弾性を保持できる弾性体は非常に高価であり、またスタックの大型化、重量増になる。 However, the technique of Patent Document 1 requires a measure such as increasing the thickness of the cell in order to ensure its strength so that the cell is not damaged, and the stack becomes heavier and larger. This is contrary to the light and small requirements required for vehicles.
Further, in the technique of Patent Document 2, densification of the conductive felt due to heat proceeds during use, resulting in a decrease in cushioning properties and contact failure due to deformation. When used for a vehicle, the vibration and impact are intense and the cushioning property is lowered and the deformation is more likely to proceed.
Furthermore, the technique of Patent Document 3 is a method of pressing the conductive felt by inserting an elastic body, that is, an elastic body, but an elastic body that can stably retain elasticity under the temperature environment of SOFC is very expensive, It will also increase the size and weight of the stack.

本発明は、このような従来技術の有する課題に鑑みてなされたものであり、その目的とするところは、集電体の緻密化やズレによる燃料電池セル、集電体、セパレータ相互の電気的な接続不良を防止でき、良好な導通性を有する燃料電池用集電構造及び固体酸化物形燃料電池スタックを提供することにある。   The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an electrical connection between the fuel cell, the current collector, and the separator due to densification or displacement of the current collector. An object of the present invention is to provide a current collecting structure for a fuel cell and a solid oxide fuel cell stack that can prevent poor connection and have good electrical conductivity.

本発明者らは、上記課題を解決すべく鋭意検討を重ねた結果、燃料電池セルやセパレータにメッキにて形成された導電性突起を設け、この突起を多孔質導電体の開口に係着させることにより、上記課題が解決できることを見出し、本発明を完成するに至った。   As a result of intensive studies to solve the above-mentioned problems, the present inventors have provided conductive protrusions formed by plating on the fuel cell or separator, and engaged these protrusions with the openings of the porous conductor. As a result, the inventors have found that the above problems can be solved, and have completed the present invention.

本発明によれば、燃料電池セルやセパレータにメッキにて形成された導電性突起を設け、多孔質導電体と組み合わせることとしたため、燃料電池セル〜多孔質導電体間又はセパレータ〜多孔質導電体間が３次元的に電気的に接続され、集電体の緻密化やズレの影響を防止でき、良好な導通性を有する燃料電池用集電構造及び固体酸化物形燃料電池スタックを提供できる。   According to the present invention, the conductive protrusions formed by plating are provided on the fuel battery cell or the separator and combined with the porous conductor, so that the fuel battery cell and the porous conductor or between the separator and the porous conductor. Between them, the current is three-dimensionally electrically connected, the current collector can be prevented from being densified and shifted, and a current collecting structure for a fuel cell and a solid oxide fuel cell stack can be provided having good electrical conductivity.

従来の集電構造の一例を示す概略図である。It is the schematic which shows an example of the conventional current collection structure. 本発明の燃料電池用集電体の仕様例を示す概略図である。It is the schematic which shows the example of a specification of the collector for fuel cells of this invention. 突起の一例を示す概略図である。It is the schematic which shows an example of protrusion. おろし金状の突起の一例を示す概略図である。It is the schematic which shows an example of a grater-like protrusion. 金属細線群の一例を示す概略図である。It is the schematic which shows an example of a metal fine wire group. 発泡金属の内部を示す断面概略図である。It is a section schematic diagram showing the inside of a metal foam. 多孔質導電材及び突起に被覆を施した様子を示す概略図である。It is the schematic which shows a mode that the porous electrically conductive material and protrusion were coat | covered. 金属基板の突起先端部のみが多孔質集電体の開口部に入り込んでいる様子を示す概略図である。It is the schematic which shows a mode that only the protrusion front-end | tip part of a metal substrate has entered into the opening part of the porous electrical power collector. 固体電解質形燃料電池スタックの一例を示す概略図である。It is the schematic which shows an example of a solid electrolyte form fuel cell stack. （ａ），（ｂ）は、本例の燃料電池用集電構造を構成する燃料電池セルを示す図、（ｃ）は、その燃料電池セルに配設する集電体を示す図である。実施例１で用いた燃料電池セル及び集電構造（セパレータを除く）を示す概略図である。(A), (b) is a figure which shows the fuel cell which comprises the current collection structure for fuel cells of this example, (c) is a figure which shows the electrical power collector arrange | positioned in the fuel battery cell. It is the schematic which shows the fuel cell used in Example 1, and current collection structure (except for a separator). 実施例１で用いた燃料電池セルの作製プロセスを示す概略図である。FIG. 3 is a schematic view showing a manufacturing process of a fuel cell used in Example 1. 実施例１で用いたセパレータ及び燃料電池スタックを示す概略図である。It is the schematic which shows the separator and fuel cell stack which were used in Example 1. FIG. 燃料電池セルの作製プロセスの一例を示す概略図である。It is the schematic which shows an example of the preparation process of a fuel cell. 実施例２の集電構造を示す概略図である。6 is a schematic view showing a current collecting structure of Example 2. FIG. 実施例３の集電構造を示す概略図である。6 is a schematic view showing a current collecting structure of Example 3. FIG. 燃料電池セルの作製プロセスの他の例を示す概略図である。It is the schematic which shows the other example of the manufacturing process of a fuel cell. 実施例４の集電構造を示す概略図である。6 is a schematic diagram illustrating a current collecting structure of Example 4. FIG. 燃料電池セルの作製プロセスの更に他の例を示す概略図である。It is the schematic which shows the further another example of the manufacturing process of a fuel cell.

以下、本発明の燃料電池用集電構造について詳細に説明する。なお、本願特許請求の範囲及び本明細書において、「％」は特記しない限り質量百分率を示す。   Hereinafter, the current collecting structure for a fuel cell according to the present invention will be described in detail. In the claims and the present specification, “%” indicates a mass percentage unless otherwise specified.

上述の如く、本発明の燃料電池用集電構造は、平板型の固体電解質を燃料極及び空気極で挟持して成る燃料電池セル（単セル）に、集電体及びセパレータを積層した固体酸化物形燃料電池に採用される。具体的には、上記集電体として表面に複数の開口を有する多孔質導電体を用い、上記燃料電池セル、上記セパレータのいずれか一方又は双方の表面に複数の導電性の突起を設ける。そして、燃料電池セル、集電体及びセパレータは、当該開口に当該突起が入り込み、接触するように配設される。例えば、図２に示すような構成となる。
このように、多孔質導電体と導電性突起の表面（側面又は頭部）を接触させることで、相互間の導電性が良好になる。また、従来品の金属薄板や導電性フェルト等の集電体をセルに強く押し付ける方法（弾性接触）に比べて、燃料電池セルにかかる応力負担が軽減される。更に、燃料電池セルを薄く軽く設計でき、スタックの軽量化、小型化が可能となる。更にまた、燃料電池セルやセパレータ等のスタック構成部品の歪みや、多孔質導電体（例えば上述の導電性フェルト）の緻密化、変形により燃料電池セルと集電体がずれたとしても導電性突起と集電体が３次元的に接触しているため電気的導通が保持される。また、燃料電池セルの電極部に電子伝導性材料より成る導電性突起を埋設できるので電極の電気抵抗が低下しセルの出力が向上する。 As described above, the current collecting structure for a fuel cell according to the present invention is a solid oxide in which a current collector and a separator are stacked on a fuel cell (single cell) in which a flat solid electrolyte is sandwiched between a fuel electrode and an air electrode. Used in physical fuel cells. Specifically, a porous conductor having a plurality of openings on the surface is used as the current collector, and a plurality of conductive protrusions are provided on the surface of one or both of the fuel cell and the separator. The fuel cell, the current collector, and the separator are arranged so that the protrusion enters and contacts the opening. For example, the configuration is as shown in FIG.
Thus, the electrical conductivity between them becomes good by making the surface (side surface or head) of a porous conductor and a conductive protrusion contact. In addition, the stress burden on the fuel cell is reduced as compared with a conventional method (elastic contact) in which a current collector such as a thin metal plate or conductive felt is strongly pressed against the cell. Furthermore, the fuel cell can be designed to be thin and light, and the stack can be reduced in weight and size. Furthermore, even if the fuel cell and the current collector are displaced due to distortion of the stack components such as the fuel cell or separator, or densification or deformation of the porous conductor (for example, the above-mentioned conductive felt), the conductive protrusion Since the current collector is in three-dimensional contact, electrical continuity is maintained. In addition, since conductive protrusions made of an electron conductive material can be embedded in the electrode portion of the fuel cell, the electrical resistance of the electrode is lowered and the output of the cell is improved.

ここで、上記導電性突起を有する燃料電池セルやセパレータと上記多孔質導電体とは、面方向に動かないように固定することがよい。例えば、上記突起の短径の平均径を、上記開口の平均径（太さ）よりも小さくすることができる。これより、多孔質導電体の凹部内に突起先端が入り込んでストッパーとなり相互に固定されるので、集電体及び燃料電池セル（単セル）の電気的接続の長寿命化が図れる。また、本構造は、燃料電池セルの上下面や燃料電池セル同士の間に採用できる。即ち、スタック化すると各燃料電池セルの応力負担が軽減されるので良好な導通を得られる。代表的には、突起の平均径が０．１μｍ〜１ｍｍであり、開口の平均径が１μｍ〜１ｍｍであることがよい。   Here, the fuel cell or separator having the conductive protrusion and the porous conductor are preferably fixed so as not to move in the plane direction. For example, the average diameter of the short diameter of the protrusion can be made smaller than the average diameter (thickness) of the opening. Thus, the tips of the protrusions enter into the recesses of the porous conductor to become stoppers and are fixed to each other, so that the life of the electrical connection between the current collector and the fuel cell (single cell) can be extended. Moreover, this structure is employable between the upper and lower surfaces of the fuel cell and between the fuel cells. That is, when stacked, the stress burden on each fuel cell is reduced, and good conduction can be obtained. Typically, the average diameter of the protrusions is 0.1 μm to 1 mm, and the average diameter of the openings is preferably 1 μm to 1 mm.

また、上記導電性突起は、多孔質導電体の凹部の中に容易に入り込める構造であることが好ましく、例えば針状又は柱状とすることができる。具体的には、図３に示すように、針を金属板に突き刺す、表面を削っておろし金のようにする、ボンディング（バンプを使った接合）、エッチングなどにより形成できる。これより、導電性突起と多孔質導電体との接触効率が高くなり、接触抵抗がより改善され得る。
更に、導電性突起の根元部分よりも先端部を太くすることもできる。このときは、より多孔質導電体から外れにくい構造となるので有効である。
更にまた、導電性突起の先端を鍵状に湾曲させることもできる。このときは、柱状や針状の場合よりも先端部が多孔質導電体とよく接触し（多孔質導電体の凹部内に引っ掛かる）、接触抵抗を低減できる。例えば、図４に示すようなおろし金構造にすると突起の先端部が鍵状となる。
また、上記導電性突起は屈曲点を少なくとも１つ有する形状であることが好ましい。これより、多孔質導電体の開口内部での接触密度が向上し易く、また多孔質導電体により絡まり易い構造となる。
上述した導電性突起は、代表的には、金属ファイバーや金属フィラーなどの一部を燃料電池セルやセパレータに埋設して形成したり、導電性突起材を電極材料と同時焼成して形成したり、メッキ処理により形成できる。また、構成材料としては、例えばニッケル（Ｎｉ）、鉄（Ｆｅ）、チタン（Ｔｉ）、マンガン（Ｍｎ）、コバルト（Ｃｏ）、タングステン（Ｗ）、クロム（Ｃｒ）、アルミニウム（Ａｌ）、モリブデン（Ｍｏ）、タンタル（Ｔａ）及びバナジウム（Ｖ）などの金属又はこれらを含む耐熱性合金、白金（Ｐｔ）やパラジウム（Ｐｄ）などの貴金属又はこれらを含む合金、上記耐熱性合金にこれら貴金属を被覆したものなど、高温酸化雰囲気において表面に酸化皮膜を形成しにくい材料、高温酸化雰囲気において導電性酸化皮膜を形成する材料などが挙げられる。 Moreover, it is preferable that the said electroconductive protrusion is a structure easily penetrated in the recessed part of a porous conductor, for example, can be made into a needle shape or a column shape. Specifically, as shown in FIG. 3, it can be formed by piercing a needle into a metal plate, scraping the surface like a grater, bonding (bonding using bumps), etching, or the like. Thereby, the contact efficiency between the conductive protrusion and the porous conductor is increased, and the contact resistance can be further improved.
Furthermore, the tip portion can be made thicker than the base portion of the conductive protrusion. In this case, the structure is more effective because it is more difficult to come off the porous conductor.
Furthermore, the tip of the conductive protrusion can be curved like a key. At this time, the tip portion comes into contact with the porous conductor better than when it is columnar or needle-shaped (it gets caught in the recess of the porous conductor), and the contact resistance can be reduced. For example, when the grater structure as shown in FIG. 4 is used, the tip of the protrusion becomes a key.
The conductive protrusion preferably has a shape having at least one bending point. As a result, the contact density inside the opening of the porous conductor is likely to be improved, and the structure is easily entangled by the porous conductor.
The conductive protrusions described above are typically formed by embedding a part of a metal fiber or metal filler in a fuel cell or separator, or formed by simultaneously firing a conductive protrusion material with an electrode material. It can be formed by plating. Moreover, as a constituent material, for example, nickel (Ni), iron (Fe), titanium (Ti), manganese (Mn), cobalt (Co), tungsten (W), chromium (Cr), aluminum (Al), molybdenum ( Metals such as Mo), tantalum (Ta) and vanadium (V) or heat-resistant alloys containing them, precious metals such as platinum (Pt) and palladium (Pd) or alloys containing these, and the above heat-resistant alloys are coated with these precious metals Examples thereof include materials that are difficult to form an oxide film on the surface in a high-temperature oxidizing atmosphere, and materials that form a conductive oxide film in a high-temperature oxidizing atmosphere.

一方、上記多孔質導電体としては、例えば、金属細線から成るものを使用できる（図５の（１））。この場合は、燃料電池セル同士を相互に傷つけることなく電気的に接触できる。例えば、弾力性を有する金属細線を複雑に絡み合わせたもの、具体的には、太さ１００μｍ以下の金属細線で形成された、いわゆる金属フェルトなどの形態で使用できる。なお、多孔質導電体は多くの隙間を含み比重の軽いものが望ましい。
また、上記多孔質導電体としては、材質の異なる複数の金属細線を混紡したものを使用できる（図５の（２））。このときは、複数種の金属又は合金から成る金属細線を適宜組合せて混紡することにより、固溶したり収縮して多孔性が低下する（へたる）ことを防止できる。例えば、かかる金属細線の太さを１００μｍ以下とし、これを複雑に入り組ませ、複数の材料を均一に混紡して、気孔率２０〜９８％である多孔質導電体を形成できる。
更に、上記多孔質導電体としては、材質の異なる複数の金属細線を接合したものを使用できる（図５の（３））。このときは、複数種の金属又は合金から成る金属細線を適宜組合せ、互いを接合することにより、金属細線がバラけにくくなり、また、多孔質導電体が解けてやせるのを防止できる。
更にまた、上記多孔質導電体としては、連続空孔を有する発泡金属を使用できる。このときは、燃料電池セル同士を相互に傷つけることなく電気的に接触できる。例えば、図６に示すように、気孔率２０〜９８％のものを使用できる。 On the other hand, as the porous conductor, for example, one made of a fine metal wire can be used ((1) in FIG. 5). In this case, the fuel cells can be electrically contacted without damaging each other. For example, it can be used in the form of a so-called metal felt formed by intricately intertwining elastic thin metal wires, specifically, a thin metal wire having a thickness of 100 μm or less. The porous conductor preferably has a small specific gravity including many gaps.
Further, as the porous conductor, a material obtained by mixing a plurality of fine metal wires of different materials can be used ((2) in FIG. 5). At this time, it is possible to prevent the porosity from being reduced due to solid solution or shrinkage by mixing and combining thin metal wires made of a plurality of types of metals or alloys as appropriate. For example, the thickness of the fine metal wire is set to 100 μm or less, which is complicatedly mixed, and a plurality of materials are uniformly mixed to form a porous conductor having a porosity of 20 to 98%.
Further, as the porous conductor, one obtained by joining a plurality of fine metal wires of different materials can be used ((3) in FIG. 5). At this time, by appropriately combining thin metal wires made of a plurality of types of metals or alloys and joining them together, the fine metal wires are less likely to be loosened, and the porous conductor can be prevented from being melted.
Furthermore, as the porous conductor, a foam metal having continuous pores can be used. At this time, the fuel cells can be electrically contacted without damaging each other. For example, as shown in FIG. 6, those having a porosity of 20 to 98% can be used.

また、上記多孔質導電体、上記導電性突起のいずれか一方又は双方は、図７に示すように、耐熱性、耐酸化性を有する導電性材料、例えば上記導電体や突起を構成する材料を含む合金、当該材料とは異なる材料又は導電性セラミックス、及びこれらを任意に組み合わせたもので被覆されていることが好ましい。これより、空気極側の集電が（貴金属製のときなどに比べて）低コストになり得る。また、部分的に被覆することで効率良く接触抵抗を低減できる。例えば、空気極側には、ペロブスカイト型ランタン系酸化物材料又はそれらを含む複合材料を被覆できる。また、両電極には、白金（Ｐｔ）やパラジウム（Ｐｄ）などの貴金属又はこれらを含む合金を被覆できる。
代表的な被覆方法としては、無電解メッキによりＰｔなどの貴金属又はその化合物を被覆する方法、スパッタなどの真空成膜により貴金属やペロブスカイト型ランタン系酸化物層を設ける方法、電解メッキにより導電性金属を成膜する方法（例えばＳＵＳ金属上にＮｉ成膜など）が挙げられる。 In addition, as shown in FIG. 7, either or both of the porous conductor and the conductive protrusion are made of a conductive material having heat resistance and oxidation resistance, for example, a material constituting the conductive body and the protrusion. It is preferably coated with an alloy containing, a material different from the material or conductive ceramics, and an arbitrary combination thereof. As a result, the current collector on the air electrode side can be low in cost (compared to when it is made of a noble metal). Moreover, contact resistance can be efficiently reduced by partially covering. For example, the air electrode side can be coated with a perovskite lanthanum oxide material or a composite material containing them. Further, both electrodes can be coated with a noble metal such as platinum (Pt) or palladium (Pd) or an alloy containing these.
Typical coating methods include a method of coating a noble metal such as Pt or a compound thereof by electroless plating, a method of providing a noble metal or a perovskite lanthanum oxide layer by vacuum film formation such as sputtering, or a conductive metal by electrolytic plating. (E.g., Ni film formation on SUS metal).

更に、上記セパレータとしては、例えばフェライト系ステンレス、もしくはニッケル（Ｎｉ）、鉄（Ｆｅ）、チタン（Ｔｉ）、マンガン（Ｍｎ）、コバルト（Ｃｏ）、タングステン（Ｗ）、クロム（Ｃｒ）、アルミニウム（Ａｌ）、モリブデン（Ｍｏ）、タンタル（Ｔａ）及びバナジウム（Ｖ）などの金属又はこれらを含む耐熱性合金、白金（Ｐｔ）やパラジウム（Ｐｄ）などの貴金属又はこれらを含む合金、上記耐熱性合金にこれら貴金属を被覆したものなど、高温酸化雰囲気において表面に酸化皮膜を形成しにくい材料、高温酸化雰囲気において導電性酸化皮膜を形成する材料などが挙げられる。   Further, as the separator, for example, ferritic stainless steel, nickel (Ni), iron (Fe), titanium (Ti), manganese (Mn), cobalt (Co), tungsten (W), chromium (Cr), aluminum ( Metals such as Al), molybdenum (Mo), tantalum (Ta) and vanadium (V) or heat-resistant alloys containing these metals, noble metals such as platinum (Pt) and palladium (Pd) or alloys containing these metals, and the above heat-resistant alloys Examples thereof include materials that are difficult to form an oxide film on the surface in a high-temperature oxidizing atmosphere, and materials that form a conductive oxide film in a high-temperature oxidizing atmosphere.

次に、本発明の固体酸化物形燃料電池スタックについて詳細に説明する。
本発明の固体酸化物型燃料電池スタックは、上述の燃料電池用集電構造を有する。この集電構造は、燃料電池セルを連結してスタック化する際に、各燃料電池セル間に採用される。なお、燃料電池セルは燃料極層及び空気極層で固体電解質層を挟持して成る。
このように、多孔質導電体と導電性突起を組み合わせた集電構造を採用することで、燃料電池セルの強度が小さくてもスタック化可能となる。また、固体電解質層を薄く設計でき、更には出力を向上しつつ、従来の燃料電池スタックよりも軽量化できる。更に、各燃料電池セルの両面（各電極層の表面）に、上述の集電構造を形成することで燃料電池セルを強く押さえつけることなく（弾性接触させずに）集電できる。言い換えれば、燃料電池セルに負担をかけずに良好な導通が得られるので、燃料電池セルに歪みが生じたときの接触不良を防止できる。また、導電性突起が多孔質導電体の凹部内に入り込むことで、多孔質集電体が面方向にズレない（中で踊ってしまわない）ようになり、また双方が接触していることで良好な電導性が保持される。この際、針状のように先細りの構造である突起を、針の断面直径より小さい平均開口径の多孔質集電体とを組合せ、突起の先端部のみ（全体ではなく）が多孔質集電体の開口部に入り込んで接触する形態でも良い。この形態の一例を図８に示す。
なお、上記「スタック」とは、ガス導入機構を有する発電要素をいい、例えば図９に示すような構成が挙げられる。また、上記「多孔質導電体」について、開口の大きさや凹部の形状は、ガス透過性及びガス拡散性を発揮できれば特に制限はなく、例えば、電気伝導性に優れる金属フェルトや発泡金属などで形成できる。 Next, the solid oxide fuel cell stack of the present invention will be described in detail.
The solid oxide fuel cell stack of the present invention has the above-described current collecting structure for fuel cells. This current collecting structure is employed between the fuel cells when the fuel cells are connected and stacked. The fuel cell is formed by sandwiching a solid electrolyte layer between a fuel electrode layer and an air electrode layer.
In this way, by adopting a current collecting structure in which a porous conductor and conductive protrusions are combined, stacking is possible even if the strength of the fuel cell is low. Further, the solid electrolyte layer can be designed to be thin, and further, the output can be improved and the weight of the conventional fuel cell stack can be reduced. Furthermore, by forming the above-described current collecting structure on both surfaces of each fuel cell (the surface of each electrode layer), current can be collected without strongly pressing the fuel cell (without elastic contact). In other words, since good conduction can be obtained without imposing a burden on the fuel cell, contact failure when the fuel cell is distorted can be prevented. In addition, since the conductive protrusions enter into the recesses of the porous conductor, the porous current collector does not shift in the plane direction (does not dance inside), and both are in contact with each other. Good electrical conductivity is maintained. At this time, the protrusion having a tapered structure such as a needle is combined with a porous current collector having an average opening diameter smaller than the cross-sectional diameter of the needle, and only the tip (not the whole) of the protrusion is a porous current collector. It may be a form that enters and contacts the opening of the body. An example of this form is shown in FIG.
The “stack” refers to a power generation element having a gas introduction mechanism, and includes, for example, a configuration as shown in FIG. In addition, with respect to the “porous conductor”, the size of the opening and the shape of the recess are not particularly limited as long as the gas permeability and gas diffusibility can be exhibited. For example, the porous conductor is formed of metal felt or foam metal having excellent electrical conductivity. it can.

以下、本発明を実施例及び比較例により更に詳細に説明するが、本発明はこれら実施例に限定されるものではない。   EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

（実施例１）
図１０に、本例の燃料電池用集電構造を構成する燃料電池セル（ａ、ｂ）及びこれに配設する集電体（ｃ）を示す。なお、このセルは電解質層を支持基板とする電解質支持型である。
この燃料電池セル１は、電解質層３の両面を空気極層２と燃料極層４で挟持して成る。
電解質層３は、１２ｃｍ角程度の大きさで厚さ１００μｍの８ｍｏｌ％イットリアを添加した安定化ジルコニア（以下「８ＹＳＺ」という）から成る。また、電解質層３は、電極が形成され他の燃料電池セルとスタック化した際に当該セルを支えるとともにガスシール部やガス流路が形成されている支持部３ａを含む。
空気極層２と燃料極層４は１０ｃｍ角程度であり、厚さ１００μｍ程度の厚さに焼き付けられている。燃料極層４はＮｉＯ−ＹＳＺを主成分とし、空気極層２はＬＳＭを主成分として成る。また、両電極層の表面には導電性突起５として、耐熱性、耐酸化雰囲気及び耐還元雰囲気に優れるＰｔファイバーが５％程度、電極層の形成とともに焼き付けられている。このファイバー５は太さ５０μｍ程度、長さ２〜４ｍｍ前後の針状である。なお、望ましくは、複数の屈曲、カール、らせん状の形状を有し、更には先端と末端（根元）とで大きさや重量が異なる形状であり、電極層表面から突起状に張り出した構造をとり易いものがよい。
一方、かかる燃料電池セル１には、集電体として耐熱金属からなる数十μｍ太さの金属繊維を編みこんだ金属フェルト６が重ねられ、３次元的な接触が図られている。 Example 1
FIG. 10 shows the fuel cell (a, b) constituting the current collector structure for the fuel cell of this example, and the current collector (c) disposed thereon. This cell is an electrolyte support type using an electrolyte layer as a support substrate.
This fuel cell 1 is formed by sandwiching both surfaces of an electrolyte layer 3 between an air electrode layer 2 and a fuel electrode layer 4.
The electrolyte layer 3 is made of stabilized zirconia (hereinafter referred to as “8YSZ”) to which 8 mol% yttria having a size of about 12 cm square and a thickness of 100 μm is added. In addition, the electrolyte layer 3 includes a support portion 3a that supports a cell when an electrode is formed and is stacked with another fuel cell, and a gas seal portion and a gas flow path are formed.
The air electrode layer 2 and the fuel electrode layer 4 are about 10 cm square, and are baked to a thickness of about 100 μm. The fuel electrode layer 4 is mainly composed of NiO-YSZ, and the air electrode layer 2 is mainly composed of LSM. In addition, about 5% of Pt fiber excellent in heat resistance, oxidation resistance atmosphere, and reduction resistance atmosphere is baked on the surfaces of both electrode layers as the electrode layers are formed. The fiber 5 has a needle shape having a thickness of about 50 μm and a length of about 2 to 4 mm. Desirably, it has a plurality of bent, curled, and spiral shapes, and further has a shape and a weight that differ from each other at the tip and end (base), and has a structure protruding from the surface of the electrode layer. Easy thing is good.
On the other hand, a metal felt 6 woven with metal fibers made of a heat-resistant metal having a thickness of several tens of μm is stacked on the fuel cell 1 as a current collector to achieve a three-dimensional contact.

ここで、図１１（ａ）に燃料電池セル１の作製フローを示す。
まず電解質材料として、８ＹＳＺのスラリーを用いドクターブレード法によりグリーンシートを作製し、所定の大きさに切り出すとともに、穴あけ加工を行い電解質層の仮成型体を作製した。また、燃料極材料として、ＮｉＯ−ＹＳＺのスラリーにＰｔファイバーを５％加え、撹拌した後スリップキャスト法により燃料極のグリーンシートを作製し、所定の大きさに切り出して燃料極シートを作製した。
次いで、電解質、燃料極のシートをそれぞれ重ね１４００℃程度の熱処理を行い焼結し、半燃料電池セルとした。
更に、空気極材料として、ＬＳＭのスラリーに再び５％のＰｔファイバーを加え、燃料極と同様に空気極シートを作製した。
最後に半燃料電池セルに空気極シートを貼り付け１０００℃程度で熱処理を行い燃料電池セルを完成させた。 Here, FIG. 11A shows a manufacturing flow of the fuel battery cell 1.
First, as an electrolyte material, a green sheet was prepared by a doctor blade method using 8YSZ slurry, cut into a predetermined size, and drilled to prepare a temporary molded body of an electrolyte layer. Further, as a fuel electrode material, 5% of Pt fiber was added to NiO—YSZ slurry and stirred, and then a green sheet of a fuel electrode was prepared by a slip casting method, and cut into a predetermined size to prepare a fuel electrode sheet.
Next, the electrolyte and fuel electrode sheets were stacked and heat treated at about 1400 ° C. to sinter them, thereby obtaining a semi-fuel cell.
Further, 5% Pt fiber was added again to the LSM slurry as an air electrode material, and an air electrode sheet was produced in the same manner as the fuel electrode.
Finally, an air electrode sheet was attached to the half fuel cell, and heat treatment was performed at about 1000 ° C. to complete the fuel cell.

図１２に、図１０で示した燃料電池セル及び集電体に配設するセパレータ（ａ）、並びにこれらを用いた集電構造を有する燃料電池スタック（ｂ、ｃ）を示す。
セパレータ（ａ）は耐熱金属から成る。厚さ４．５ｍｍで、一方の面上に深さ２ｍｍの空気流路、他方の面上に同様に２ｍｍ深さの燃料流路が形成され、外周部の燃料電池セル支持部３ａと重なる部分にはガス供給・排気の４つのマニホールド７、８が形成されている。このセパレータと燃料電池セルを集電体を介して交互に積層することにより燃料電池スタックが形成される。
また、図１２の（ｂ）、（ｃ）に示すように、空気極層側には空気、燃料極層側には空気が供給、排気される。また、各燃料電池セルは、この集電構造及びセパレータを介して直列に接続される。 FIG. 12 shows a separator (a) disposed on the fuel cell and the current collector shown in FIG. 10, and a fuel cell stack (b, c) having a current collecting structure using them.
The separator (a) is made of a refractory metal. A portion having a thickness of 4.5 mm, an air flow path having a depth of 2 mm on one surface, and a fuel flow path having a depth of 2 mm on the other surface, and overlapping the fuel cell support portion 3a on the outer periphery. Four manifolds 7 and 8 for gas supply / exhaust are formed. A fuel cell stack is formed by alternately laminating the separators and fuel cells via current collectors.
Further, as shown in FIGS. 12B and 12C, air is supplied to the air electrode layer side, and air is supplied to the fuel electrode layer side and exhausted. Moreover, each fuel cell is connected in series via this current collection structure and a separator.

なお、集電体として用いる金属フェルトは、金属繊維の絡み方が面方向は密であるが、厚さ方向では面方向に比較すると疎である。このため、電気抵抗は面方向では低いか、電流を流す厚さ方向では高くなってしまう。しかし、本例では金属ファイバーが厚さ方向に挿入されるため、金属フェルトの厚さ方向の抵抗が低減されている。
また、本例では電解質支持型セルを用いたが、これに限定されるものではなく、例えば、図１１（ｂ）に示すように電極支持型においても適用は可能である。この場合、燃料極基板上に電解質膜をスクリーン印刷法にて成膜、焼成した後、電解質支持型とともにスリップキャスト法にて作製したＰｔファイバー入り空気極シートを重ね合わせ焼成すればよい。更に、本例では電極材料にＰｔファイバーを混ぜ込んだ電極シートを電解質層に張り合わせて作製しているが、これに限定されるものではなく、例えば、図１３の（ｃ）、（ｄ）に示すように、電解質層にＰｔフィラーを分散後電極材スラリーを塗布する方法や、電極材を成膜後にＰｔファイバーを分散し、再度スラリーを塗布した後に焼成する方法などでも作製できる。 Note that the metal felt used as the current collector is dense in the surface direction in terms of the entanglement of the metal fibers, but is sparse in the thickness direction compared to the surface direction. For this reason, the electrical resistance is low in the plane direction or high in the thickness direction in which current flows. However, in this example, since the metal fiber is inserted in the thickness direction, the resistance in the thickness direction of the metal felt is reduced.
Moreover, although the electrolyte support type cell was used in this example, it is not limited to this, For example, it can apply also to an electrode support type as shown in FIG.11 (b). In this case, an electrolyte membrane is formed on the fuel electrode substrate by screen printing and fired, and then an air electrode sheet containing Pt fibers produced by slip casting with an electrolyte support mold is fired in an overlapping manner. Furthermore, in this example, an electrode sheet in which Pt fiber is mixed with an electrode material is bonded to the electrolyte layer, but the present invention is not limited to this. For example, as shown in (c) and (d) of FIG. As shown, the electrode material slurry can be applied after dispersing the Pt filler in the electrolyte layer, or the Pt fiber can be dispersed after forming the electrode material, and the slurry can be applied again and fired.

（実施例２）
図９に示す構造の燃料電池スタックを作製し、その出力の経時変化を測定した。
燃料電池セル１には１２ｃｍ角、厚み５０μｍの８モル％Ｙ２Ｏ３添加ＺｒＯ２（８ＹＳＺ）電解質板に１０ｃｍ角でＮｉＯ−８ＹＳＺの燃料極１０μｍ、及びＬａ０．８Ｓｒ０．２ＭｎＯ３の空気極１０μｍを公知の手法により印刷・焼成したものを用いた。また、両電極の表面には導電性突起５として、耐熱性、耐酸化雰囲気及び耐還元雰囲気に優れるＰｔファイバーが５％程度、電極層の形成と同時に焼き付けられている。
また、燃料極層側の集電体６としてニッケルの２０μｍの金属細線より成る金属フェルト、空気極層側の集電体として同形状のＳＵＳ３１６の表面をＰｔメッキでコーティングした金属細線より成る多孔質導電体を用いた。
更に、セパレータ９として表面を加工し長さ１０００μｍ、平均径１００μｍの突起を両面に形成したおろし金状ＳＵＳ基板を用い、図９のように積層し２０枚セル板を含むスタックとした。なお、図１４に、本例の集電構造の拡大図を示す。
燃料極層側に水素、空気極層側に空気を導入し、７００℃で発電させた出力の経時変化は、評価開始時には２００Ｗ、１０００時間経過後には１９３Ｗ、２０００時間経過後には１８８Ｗであった。このように、本例の集電構造を有する燃料電池スタックは、導電性突起と多孔質導電体が３次元的に接触しているため電気的導通に優れる。また、緻密化、変形に対するマージンが向上した燃料電池スタックとなる。更に、集電体の縦方向の電気抵抗もより改善されている。 (Example 2)
A fuel cell stack having the structure shown in FIG. 9 was produced, and the change with time of the output was measured.
The fuel cell 1 has a 12 cm square, 50 mol thick 8 mol% Y 2 O 3 -added ZrO 2 (8YSZ) electrolyte plate, a 10 cm square NiO-8YSZ fuel electrode 10 μm, and La 0.8 Sr 0.2 MnO 3. The air electrode 10 μm was printed and fired by a known method. In addition, about 5% of Pt fibers excellent in heat resistance, oxidation resistance atmosphere, and reduction resistance atmosphere are baked on the surfaces of both electrodes simultaneously with the formation of the electrode layers as conductive protrusions 5.
Further, the current collector 6 on the fuel electrode layer side is made of a metal felt made of nickel fine metal wires of 20 μm, and the current collector on the air electrode layer side is made of a porous metal wire made of SUS316 coated with Pt plating. A conductor was used.
Furthermore, using a grater-like SUS substrate with a surface processed as a separator 9 and having protrusions with a length of 1000 μm and an average diameter of 100 μm formed on both sides, a stack including 20 cell plates was laminated as shown in FIG. In addition, in FIG. 14, the enlarged view of the current collection structure of this example is shown.
The time-dependent change in output when hydrogen was introduced into the fuel electrode layer side and air was introduced into the air electrode layer side to generate power at 700 ° C. was 200 W at the start of evaluation, 193 W after 1000 hours, and 188 W after 2000 hours. . Thus, the fuel cell stack having the current collecting structure of this example is excellent in electrical conduction because the conductive protrusion and the porous conductor are in three-dimensional contact. In addition, the fuel cell stack has improved margins for densification and deformation. Furthermore, the electrical resistance in the vertical direction of the current collector is further improved.

（実施例３）
燃料電池セル上の導電性突起をメッキにて形成した以外は、実施例１と同様の手順を繰り返して、本例の集電構造を得た。図１５に集電構造の拡大図、図１６にその作製プロセスを示す。
図１６の（ａ）に示すように、まず、８ＹＳＺの電解質層のそれぞれの面に燃料極層、空気極層を焼付けした燃料電池セルを作製した。
次いで、燃料電池セルの両面にＰｔ等の電解メッキの起点となる導電性材料を１００ｎｍ程度成膜した後、両面にフィルムレジストを被覆し、フォトリソグラフィ技術により所定の位置にＰｔ層の露出した開口部を形成した（ｂ）。
更に、電解メッキを施し電極表面上にＰｔから成る導電性突起を形成した（ｃ）。
更にまた、レジストを薬液処理で除去した（ｄ）。 (Example 3)
A current collecting structure of this example was obtained by repeating the same procedure as in Example 1 except that the conductive protrusions on the fuel cell were formed by plating. FIG. 15 is an enlarged view of the current collecting structure, and FIG. 16 shows a manufacturing process thereof.
As shown in FIG. 16A, first, a fuel battery cell was fabricated in which a fuel electrode layer and an air electrode layer were baked on each surface of the 8YSZ electrolyte layer.
Next, a conductive material such as Pt, which is the starting point for electrolytic plating, is formed on both sides of the fuel cell, and then a film resist is coated on both sides, and the Pt layer is exposed at a predetermined position by photolithography. Part (b) was formed.
Further, electrolytic plating was performed to form conductive protrusions made of Pt on the electrode surface (c).
Furthermore, the resist was removed by chemical treatment (d).

本例の集電構造は、実施例１の集電構造の効果に加え、燃料電池セル作製後の追加処理で導電性突起を形成でき、これまでと同様のセル作製プロセスを手を加えることなく利用できる。また、メッキ時間の調整により導電性突起の先端部を大きくでき、これより金属フェルトから外れにくい形状となり得る。   In addition to the effects of the current collecting structure of the first embodiment, the current collecting structure of this example can form conductive protrusions by additional processing after the fabrication of the fuel cell, and without changing the cell fabrication process similar to the conventional one. Available. Further, the tip end portion of the conductive protrusion can be enlarged by adjusting the plating time, and the shape can be more difficult to come off from the metal felt.

（実施例４）
燃料電池セルの電極層内に導電性突起として耐熱金属から成るフィラーを埋め込んだ以外は、実施例３と同様の手順を繰り返して、本例の集電構造を得た。図１７に集電構造の拡大図を示す。なお、上記導電性突起は、電解質層上に電極層を形成する際、電極材料に数百ｎｍ〜数十μｍの金属ファイバー材料（実施例１で使用したもの）と同様の材料から成るフィラーを混ぜ込み、焼成して得た。
本例の集電構造は、電極層内に金属フィラーが埋め込まれていることから、メッキにより形成された導電性突起の電極層への接着性が一層強化される。 Example 4
A current collecting structure of this example was obtained by repeating the same procedure as in Example 3 except that a filler made of a refractory metal was embedded as a conductive protrusion in the electrode layer of the fuel cell. FIG. 17 shows an enlarged view of the current collecting structure. In addition, the conductive protrusion has a filler made of the same material as the metal fiber material (used in Example 1) of several hundred nm to several tens of μm as the electrode material when the electrode layer is formed on the electrolyte layer. It was obtained by mixing and baking.
In the current collecting structure of this example, since the metal filler is embedded in the electrode layer, the adhesion of the conductive protrusions formed by plating to the electrode layer is further enhanced.

（実施例５）
燃料電池セルにおいて各電極を多層構造とした以外は、実施例１と同様の手順を繰り返して、本例の集電構造を得た。図１８に集電構造の作製プロセスを示す。なお、各電極は、一旦電解質層上に電極層を焼き付け、形成した後に耐熱金属から成るフィラーを含む第２の電極層を形成して得た。 (Example 5)
A current collecting structure of this example was obtained by repeating the same procedure as in Example 1 except that each electrode in the fuel cell had a multilayer structure. FIG. 18 shows a manufacturing process of the current collecting structure. Each electrode was obtained by baking the electrode layer once on the electrolyte layer and forming a second electrode layer containing a filler made of a refractory metal.

一般的に、電極層は燃料極１４００℃、空気極は１０００℃といった高温での焼成プロセスにより形成される。そのため導電性材料は当然この温度で導電性等を失わない程度の耐熱性が必要であった。
本例によれば、電極の焼付けと導電性突起の形成が別工程となるため、導電性突起の構成材料の耐熱性はＳＯＦＣの動作温度程度で十分となり、より多くの導電性材料が適用可能になる。また、第２の電極層は、導電性とガス透過性を有していれば触媒作用は特に必要なく、ＳＯＦＣ動作温度程度の耐熱性を有する金属のペーストやＺｎ、Ｓｎ等の酸化物を用いた導電性材料のペーストなどからも作製できる。 In general, the electrode layer is formed by a firing process at a high temperature of 1400 ° C. for the fuel electrode and 1000 ° C. for the air electrode. For this reason, the conductive material naturally needs to have heat resistance that does not lose conductivity at this temperature.
According to this example, since the electrode baking and the formation of the conductive protrusions are separate processes, the heat resistance of the constituent material of the conductive protrusions is sufficient at the operating temperature of SOFC, and more conductive materials can be applied. become. Further, the second electrode layer is not particularly required to have a catalytic action as long as it has conductivity and gas permeability, and uses a metal paste having heat resistance of about the SOFC operating temperature or an oxide such as Zn or Sn. It can also be produced from a paste of conductive material.

（比較例）
燃料電池セルには１２ｃｍ角、厚み５０μｍの８モル％Ｙ２Ｏ３添加ＺｒＯ２（８ＹＳＺ）電解質板に１０ｃｍ角でＮｉＯ−８ＹＳＺの燃料極１０μｍ、及びＬａ０．８Ｓｒ０．２ＭｎＯ３の空気極１０μｍを公知の手法により印刷・焼成したものを用いた。燃料極層側の集電体としてニッケルの２０μｍの金属細線より成る多孔質導電体、空気極層側の集電体として形状の同じＳＵＳ３１６の表面をＰｔメッキでコーティングした金属細線より成る多孔質導電体を用いた。燃料極層側の集電体と空気極層側の集電体の間にはセパレータ及び集電材としてＳＵＳ３１６板を用い、これらを積層し２０枚のセル板を含むスタックとした。
燃料極層側に水素、空気極層側に空気を導入し、７００℃で発電させた出力の経時変化は、評価開始時には１９８Ｗ、１０００時間経過後には１５７Ｗ、２０００時間経過後には１２３Ｗであった。 (Comparative example)
The fuel cell has a 12 cm square and 50 μm thick 8 mol% Y 2 O 3 -added ZrO 2 (8YSZ) electrolyte plate and a 10 cm square NiO-8YSZ fuel electrode 10 μm, and La 0.8 Sr 0.2 MnO 3 . An air electrode having a thickness of 10 μm printed and fired by a known method was used. A porous conductor composed of a fine nickel wire of 20 μm of nickel as a current collector on the fuel electrode layer side, and a porous conductor composed of a thin metal wire coated with Pt plating on the surface of SUS316 having the same shape as the current collector on the air electrode layer side Using the body. A SUS316 plate was used as a separator and current collector between the current collector on the fuel electrode layer side and the current collector on the air electrode layer side, and these were stacked to form a stack containing 20 cell plates.
The time-dependent change in the output when hydrogen was introduced into the fuel electrode layer side and air was introduced into the air electrode layer side to generate power at 700 ° C. was 198 W at the start of evaluation, 157 W after 1000 hours, and 123 W after 2000 hours. .

１ 燃料電池セル
２ 空気極層
３ 電解質層
４ 燃料極層
５ 導電性突起（Ｐｔファイバー）
６ 集電体（金属フェルト）
７ 空気排気マニホールド
８ 燃料ガス供給マニホールド
９ セパレータ
１０ セパレータ突起部
１１ 金属ファイバー材料 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Air electrode layer 3 Electrolyte layer 4 Fuel electrode layer 5 Conductive protrusion (Pt fiber)
6 Current collector (metal felt)
7 Air exhaust manifold 8 Fuel gas supply manifold 9 Separator 10 Separator protrusion 11 Metal fiber material

Claims (11)

平板型の固体電解質を燃料極及び空気極で挟持して成る燃料電池セルに、集電体及びセパレータを積層した固体酸化物形燃料電池の集電構造であって、
上記集電体は表面に複数の開口を有する多孔質導電体であり、
上記燃料電池セル及び／又は上記セパレータは表面に複数の導電性の突起を有し、
上記導電性突起が、メッキにて形成され、
当該開口と当該突起が対向し係着していることを特徴とする燃料電池用集電構造。 A current collecting structure of a solid oxide fuel cell in which a current collector and a separator are laminated on a fuel cell formed by sandwiching a flat plate type solid electrolyte between a fuel electrode and an air electrode,
The current collector is a porous conductor having a plurality of openings on the surface,
The fuel cell and / or the separator has a plurality of conductive protrusions on the surface,
The conductive protrusion is formed by plating,
A current collecting structure for a fuel cell, wherein the opening and the protrusion are opposed to each other. 上記導電性突起の短径の平均径が、上記開口の平均径より小さいことを特徴とする請求項１に記載の燃料電池用集電構造。   2. The current collecting structure for a fuel cell according to claim 1, wherein an average diameter of a minor axis of the conductive protrusion is smaller than an average diameter of the opening. 上記導電性突起が針状又は柱状であることを特徴とする請求項１又は２に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to claim 1 or 2, wherein the conductive protrusions have a needle shape or a column shape. 上記導電性突起の根元部分よりも先端部が太いことを特徴とする請求項１又は２に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to claim 1 or 2, wherein a tip portion is thicker than a base portion of the conductive protrusion. 上記導電性突起が、導電性突起材及び電極材料を同時焼成して形成されたことを特徴とする請求項１〜４のいずれか１つの項に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to any one of claims 1 to 4, wherein the conductive protrusion is formed by simultaneously firing a conductive protrusion material and an electrode material. 上記多孔質導電体が金属細線から成ることを特徴とする請求項１〜５のいずれか１つの項に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to any one of claims 1 to 5, wherein the porous conductor is made of a thin metal wire. 上記金属細線は材質の異なる複数種類の金属細線を混紡して成ることを特徴とする請求項６に記載の燃料電池用集電構造。   7. The current collecting structure for a fuel cell according to claim 6, wherein the fine metal wires are formed by mixing a plurality of types of fine metal wires having different materials. 上記金属細線は材質の異なる複数種類の金属細線を接合して成ることを特徴とする請求項６又は７に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to claim 6 or 7, wherein the thin metal wire is formed by joining a plurality of types of thin metal wires of different materials. 上記多孔質導電体が発泡金属であることを特徴とする請求項１〜５のいずれか１つの項に記載の燃料電池用集電構造。   The current collecting structure for a fuel cell according to any one of claims 1 to 5, wherein the porous conductor is a foam metal. 上記多孔質導電体及び／又は上記導電性突起が、当該導電体又は当該突起を構成する材料を含む合金、当該導電体又は当該突起を構成する材料とは異なる材料、及び導電性セラミックスから成る群より選ばれた少なくとも１種のもの、で被覆されていることを特徴とする請求項１〜９のいずれか１つの項に記載の燃料電池用集電構造。   The porous conductor and / or the conductive protrusion is a group consisting of the conductor or an alloy containing a material constituting the protrusion, a material different from the material constituting the conductor or the protrusion, and a conductive ceramic. The current collecting structure for a fuel cell according to any one of claims 1 to 9, wherein the current collecting structure is coated with at least one selected from the above. 請求項１〜１０のいずれか１つの項に記載の燃料電池用集電構造を有することを特徴とする固体酸化物形燃料電池スタック。   A solid oxide fuel cell stack comprising the fuel cell current collecting structure according to any one of claims 1 to 10.
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