JP2004207170A - Stacked body and solid electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell with a strong stack structure having a stacked body made up of ceramic and metal firmly joined to each other, and a joint part between the ceramic and the metal. <P>SOLUTION: The stacked body 1 is formed by joining a ceramic molded body 11 (made of ScSZ or the like) and a heat-resistant alloy molded body 12 (made of 430 S/S or the like) to each other with a joining material (containing Ag, Pd, and a small amount of Ti). The fuel cell is made up of a plurality of stacked single cells. Each single cell comprises: a solid electrolyte layer (made of ScSZ or the like); a power generation layer having a fuel electrode (made of Ni and ScSZ or the like) and an air electrode (made of a composite oxide containing La, Mn, or the like); an isolation separator made of a heat-resistant alloy (made of 430 S/S or the like); and a frame made of an insulating ceramic (made of MgO-MgAl<SB>2</SB>O<SB>4</SB>or the like). At least the solid electrolyte layer and the isolation separator are joined to each other with the joining material containing Ag and Pd. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３４】
表１の結果によれば、実施例１のＹＳＺ焼結体とＳＵＳ４３０との接合の場合、結晶化ガラスペーストを使用した比較実験例１では、接合強度は４８ＭＰａと低いことが分かる。一方、Ａｇを主成分とし、Ｐｄを含有する接合材（ａ）を用いた実験例１〜３では、接合強度は１２５〜１９１ＭＰａであり、更にＣｕを含有する接合材（ｂ）を用いた実験例１０〜１１では、接合強度は１０２〜１２８ＭＰａであって、接合温度により変化するもののいずれも十分な強度であることが分かる。更に、接合材が適量（０．１〜１０質量％）のＴｉを含有する実験例４〜９及び１２では、接合強度は１３２〜２３０ＭＰａ（実験例４〜６及び８ではＹＳＺ焼結体が破壊した。）であり、特に接合雰囲気が真空である場合は、より優れていることが分かる。また、実験例４はＴｉの含有量が０．１質量％と少ないが、このように極めて少量のＴｉであっても、Ｔｉを含有しない実験例２に比べて接合強度が予測し得ないほどに大きく向上していることが分かる。更に、Ｔｉの含有量が１０質量％と多い実験例８及び９の場合、接合雰囲気がアルゴンである実験例９では、Ｔｉを含有する効果が十分に得られない傾向にある。一方、接合雰囲気が真空である実験例８では、ＹＳＺ焼結体が破壊するほど強固に接合されており、真空雰囲気における接合がより好ましいことが分かる。
【００３５】
実施例２のＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体とＳＵＳ４３０との接合の場合は、結晶化ガラスペーストを使用した比較実験例２では、接合体の研削時に剥離してしまい、接合強度の測定はできなかった。一方、Ａｇを主成分とし、Ｐｄを含有する接合材（ａ）を用いた実験例１３、更にＣｕを含有する接合材（ｂ）を用いた実験例１９では、接合強度は６７〜７８ＭＰａであり、十分な強度であることが分かる。また、接合材が適量（０．１〜１０質量％）のＴｉを含有する実験例１４〜１８及び２０では、接合強度は１３２〜２５６ＭＰａ（実験例１６及び１８ではＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体が破壊した。）であり、Ｔｉを含有することにより接合強度が大きく向上していた。特に、実験例１４はＴｉの含有量が０．１質量％と少ないが、このように極めて少量のＴｉであっても、Ｔｉを含有しない実験例１３に比べて接合強度が予測し得ないほどに大きく向上していることが分かる。更に、このＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体の場合も、実験例１６と１７とを比較すれば分かるように、真空雰囲気において接合することにより強度が大きく向上する。
【００３６】
また、実験例２、４〜６及び８（ＹＳＺ焼結体の場合）並びに実験例１３、１４〜１６及び１８（ＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体の場合）の各々における接合材に含有されるＴｉ量と接合強度との関係を図３に示す。この図３によれば、０．１質量％という極めて少量のＴｉにより接合強度が大きく向上することが分かる。更に、ＹＳＺ焼結体の場合は、Ｔｉの含有量が０．１〜１０質量％の範囲においてＹＳＺ焼結体が破壊しており、Ｔｉ含有量の増加とともに強度が僅かながら向上している。また、ＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体の場合は、Ｔｉ含有量が５質量％で接合強度が最大になり、１０質量％では強度が低下するが、それでもＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体が破壊しており、十分な強度が維持されている。
【００３７】
［２］固体電解質型燃料電池
実施例３（燃料ガス及び支燃性ガスの流路を有するセパレータを備え、２個の発電層が積層された燃料電池）
（１）燃料電池の構造
２個の発電層が積層された平板型ＳＯＦＣスタック１００の断面を図４に模式的に示す。
この平板型ＳＯＦＣスタック１００では、２個の発電層２が積層用セパレータ３１を介して積層された構造を備える。各々の発電層２は、Ｓｃにより安定化されたジルコニア（ＳｃＳＺ）からなり、厚さが２００μｍの固体電解質層２１と、その下面に設けられ、ＮｉとＳｃＳＺとからなり、厚さが３０μｍの燃料極２２と、上面に設けられ、Ｌａ_１−ｘＳｒ_ｘＭｎＯ_３系複合酸化物からなり、厚さが３０μｍの空気極２３とを有する。固体電解質層２１、燃料極２２及び空気極２３は、いずれも平面形状が正方形であり、固体電解質層２１は燃料極２２及び空気極２３より面積が大きく、燃料極２２と空気極２３は同じ大きさであって、対向した位置に設けられている。
【００３８】
２個の発電層２は、ＳＵＳ４３０からなる積層用セパレータ３１を介して積層されている。この積層用セパレータ３１の上面には燃料ガスの流路４１が、下面には支燃性ガスの流路４２が形成されている。また、上層の発電層２の上側には、ＳＵＳ４３０からなる上部セパレータ３２が配設されており、その下面には支燃性ガスの流路４２が形成されている。更に、下層の発電層２の下側には、ＳＵＳ４３０からなる下部セパレータ３３が配設されており、その上面には燃料ガスの流路４１が形成されている。
【００３９】
また、上層の発電層２の固体電解質層２１の周縁と、上部セパレータ３２及び積層用セパレータ３１の各々の周縁、並びに下層の発電層２の固体電解質層２１の周縁と、下部セパレータ３３及び積層用セパレータ３１の各々の周縁は、それぞれ接合され、接合層１０が形成されている。接合材としては、上記［１］に記載の特定の接合材のうちの固体電解質層と金属との接合に適した接合材（例えば、実験例６の接合材）が使用され、実験例６と同じ条件により強固に接合されている。
【００４０】
（２）燃料電池の作用
この固体電解質型燃料電池においては、２個の発電層の各々の固体電解質層が、ＹＳＺの２倍ほどのイオン導電率を有するＳｃＳＺにより形成されており、７５０℃程度の作動温度でも安定して電流を取り出すことができる。そのため、セラミックではなくＳＵＳ４３０等のステンレス鋼からなるセパレータを使用することができ、固体電解質層とセパレータとをＡｇ、Ｐｄ及び少量のＴｉを含有する、例えば、実施例１における実験例６の特定の接合材等により強固に接合することができる。そして、各々の接合部においては圧縮応力が残留しているものと考えられ、種々の外力に耐えられる強靭なスタック構造を形成することができる。
【００４１】
実施例４（積層された２個の単セルを有し、燃料極を基板とする外部マニホールド型燃料電池）
（１）燃料電池の構造
▲１▼発電層及び各種セパレータ
２個の発電層が積層された実施例３の燃料電池とは異なる他の構造を備える平板型ＳＯＦＣスタック１００’の外観を図５に斜視図により示す。また、図６は、図５におけるＡ−Ａ断面の模式図であり、図７は、図５におけるＢ−Ｂ断面の模式図である。
この平板型ＳＯＦＣスタック１００’では、２個の単セルが中間セパレータ３４１を介して積層されている。各々の単セルが備える発電層は、それぞれ実施例３の燃料電池と同じ材質からなり、平面形状が正方形であり、厚さが１０００μｍの燃料極２２を基板としている。この燃料極２２の表面にはそれぞれ実施例３の燃料電池と同じ材質からなり、平面方向の形状、寸法が燃料極２２と同じであり、厚さが３０μｍの固体電解質層２１が形成されている。更に、この固体電解質層２１の表面にはそれぞれ実施例３の燃料電池と同じ材質からなり、平面方向の形状が固体電解質層２１と同じであり、寸法が固体電解質層２１より小さく、厚さが３０μｍの空気極２３が形成されている。
【００４２】
上部の単セルは、中間セパレータ３４１の上面に配設されたニッケルフェルト層５、基板となる燃料極２２、固体電解質層２１、空気極２３、インコネル繊維メッシュ層６及び蓋部材３５をこの順に備える。また、インコネル繊維メッシュ層６の周面を取り囲み、下面が固体電解質層２１と接合され、上面が絶縁性セラミックであるＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体からなる枠体７を介して蓋部材３５と接合されている上部単セル用隔離セパレータ３６を有する。一方、下部の単セルは、底部材３７の上面に配設されたニッケルフェルト層５、基板となる燃料極２２、固体電解質層２１、空気極２３及びインコネル繊維メッシュ層６をこの順に備える。また、インコネル繊維メッシュ層６の周面を取り囲み、下面が固体電解質層２１と接合され、上面が枠体７を介して中間セパレータ３４１と接合されている下部単セル用隔離セパレータ３８を有する。
【００４３】
蓋部材３５、上部単セル用隔離セパレータ３６、中間セパレータ３４１、下部単セル用隔離セパレータ３８及び底部材３７は、いずれもＳＵＳ４３０により形成されている。更に、上部単セル用隔離セパレータ３６と中間セパレータ３４１、及び下部単セル用隔離セパレータ３８と底部材３７、はそれぞれＡｇ、Ｐｄ及び少量のＴｉを含有する接合材のうち、特に金属間の接合に適した組成の接合材により接合され、接合層１０が形成されている。
【００４４】
▲２▼燃料ガス導入管又は排出管、及び支燃性ガス導入管又は排出管
上部単セルにおいて、上部単セル用隔離セパレータ３６と中間セパレータ３４１との間に形成された空間には、上部単セルの燃料極２２に燃料ガスを導入するための燃料ガス導入管９１が開口している（図６参照）。また、この空間の燃料ガス導入管９１の開口部とは対角線方向の位置には、上部単セルの燃料極２２から燃料ガスを排出するための燃料ガス排出管９２が開口している（図７参照）。更に、上部単セル用隔離セパレータ３６の一方の側面側には、上部単セルの空気極２３に支燃性ガスを導入するための貫通孔３６１が設けられ（図６参照）、対向する他方の側面側の対角線方向には、上部単セルの空気極２３から支燃性ガスを排出するための貫通孔３６２が設けられている（図７参照）。これらの貫通孔３６１、３６２は、それぞれ蓋部材３５上部単セル用隔離セパレータ３６との間に形成された空間に連通されており、各々の空間には、支燃性ガスを導入するための支燃性ガス導入管９３（図６参照）、又は排気するための支燃性ガス排出管９４（図７参照）が開口している。
【００４５】
一方、下部単セルにおいて、下部単セル用隔離セパレータ３８と底部材３７との間に形成された空間には下部単セルの燃料極２２に燃料ガスを導入するための燃料ガス導入管９１が開口している（図６参照）。また、この空間の燃料ガス導入管９１の開口部とは対角線方向の位置には、下部単セルの燃料極２２から燃料ガスを排出するための燃料ガス排出管９２が開口している（図７参照）。更に、下単セル用隔離セパレータ３８の一方の側面側には、下部単セルの空気極２３に支燃性ガスを導入するための貫通孔３８１が設けられ（図６参照）、対向する他方の側面側の対角線方向には、下部単セルの空気極２３から支燃性ガスを排出するための貫通孔３８２が設けられている（図７参照）。これらの貫通孔３８１、３８２は、それぞれ中間セパレータ３４１と下部単セル用隔離セパレータ３８との間に形成された空間に連通されており、各々の空間には、支燃性ガスを導入するための支燃性ガス導入管９３（図６参照）、又は排出するための支燃性ガス排出管９４（図７参照）が開口している。
尚、この実施例４の燃料電池では、上部単セルの上面に更に他の単セルが積層された場合、蓋部材が中間セパレータとして機能することになる。また、下部単セルの下面に更に他の単セルが積層された場合、底部材が中間セパレータとして機能することになる。
【００４６】
また、上部単セル及び下部単セルの各々に燃料ガス又は支燃性ガスを導入し、又は排出するためのそれぞれの管は、本管に側管が取り付けられた構造であり、上部発電層及び下部発電層に燃料ガス又は支燃性ガスが同時に導入され、且つ排出される。更に、燃料ガス導入管と燃料ガス排出管、及び支燃性ガス導入管と支燃性ガス排出管は、この実施例４の場合は、燃料ガス及び支燃性ガスがそれぞれ対角線方向に流通するような位置に取り付けられる。これにより、上部発電層及び下部発電層の各々の燃料極と燃料ガス、及び空気極と支燃性ガスをそれぞれ効率よく接触させることができる。
【００４７】
（２）燃料電池からの電力の取り出し
この平板型ＳＯＦＣスタックでは、上部単セルの燃料極２２は、ニッケルフェルト５を介して中間セパレータ３４１と電気的に接続されている。また、中間セパレータ３４１は、インコネル繊維メッシュ６を介して下部単セルの空気極２３と電気的に接続されている。このように上部単セルと下部単セルは直列に接続されている。また、スタックを所定の作動温度に昇温させ、燃料ガス導入管９１に水素等の燃料ガスを導入して燃料極と接触させ、支燃性ガス導入管９３に空気等の支燃性ガスを導入して空気極と接触させることにより、燃料極と空気極との間に起電力が生じ、この電力を外部に取り出すことにより発電装置として機能させることができる。電力は、燃料極側においては下部単セルの下面に配設されたニッケルフェルト５を介して底部材３７に取り出され、空気極側においては上部単セルの上面に配設されたインコネル繊維メッシュ６を介して蓋部材３５に取り出され、蓋部材３５と底部材３７との間でスタック全体の電力を取り出すことができる。
【００４８】
（３）燃料電池の作用
この固体電解質型燃料電池では、２個の発電層がそれぞれ燃料極支持型であり、この構造の場合、７５０℃程度の作動温度でも電流を取り出すことができる。そのため、蓋部材、各種セパレータ及び底部材を、セラミックではなくＳＵＳ４３０等のステンレス鋼により形成することができる。上部単セル及び下部単セルの各々において、固体電解質層と隔離セパレータとは、上記［１］に記載の特定の接合材のうちの固体電解質層と金属との接合に適した接合材（例えば、実験例６の接合材）により、実験例６と同じ条件で強固に接合されている。
【００４９】
更に、上部単セル用隔離セパレータ３６と、絶縁性セラミックからなる枠体７の一面及び枠体７の他面と蓋部材３５、並びに下部単セル用隔離セパレータ３８と、絶縁性セラミックからなる枠体７の一面及び枠体７の他面と中間セパレータ３４１は、上記［１］に記載の特定の接合材のうちの絶縁性セラミックと金属との接合に適した接合材（例えば、実験例１６の接合材）により、実験例１６と同じ条件で強固に接合されている。また、上部単セル用隔離セパレータ３６と中間セパレータ３４１、及び下部単セル用隔離セパレータ３８と底部材３７は、上記［１］に記載の特定の接合材と同様の組成であり、金属間の接合に適した接合材により強固に接合されている。このように各々の接合部はいずれもＡｇ、Ｐｄ及び少量のＴｉ等を含有する接合材により接合されており、それぞれの接合部においては圧縮応力が残留しているものと考えられ、種々の外力に耐えられる強靭なスタック構造を形成することができる。
【００５０】
実施例５（積層された３個の単セルを有し、燃料極を基板とする内部マニホールド型燃料電池）
（１）燃料電池の構造
▲１▼発電層及び各種セパレータ
３個の発電層が積層された、実施例３及び４の燃料電池とは更に異なる他の構造を備える平板型ＳＯＦＣスタック１００”の外観を図８に斜視図により示す。また、図９は、図８におけるＡ−Ａ断面の模式図であり、図１０は、図８におけるＢ−Ｂ断面の模式図である。
この平板型ＳＯＦＣスタック１００”では、３個の単セルが中間セパレータ３４２、３４３を介して積層されている。各々の単セルが備える発電層は、それぞれ実施例３の燃料電池と同じ材質からなり、平面形状が正方形であり、厚さが１０００μｍの燃料極２２を基板としている。この燃料極２２の表面にはそれぞれ実施例３の燃料電池と同じ材質からなり、平面方向の形状、寸法が燃料極２２と同じであり、厚さが３０μｍの固体電解質層２１が形成されている。更に、この固体電解質層２１の表面にはそれぞれ実施例３の燃料電池と同じ材質からなり、平面方向の形状が固体電解質層２１と同じであり、寸法が固体電解質層２１より小さく、厚さが３０μｍの空気極２３が形成されている。
【００５１】
上部の単セルは、中間セパレータ３４２の上面に配設されたニッケルフェルト層５、基板となる燃料極２２、固体電解質層２１、空気極２３、インコネル繊維メッシュ層６及び蓋部材３５をこの順に備える。また、下面が固体電解質層２１及び金属製枠体８２と接合され、上面が絶縁性セラミックであるＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体からなる枠体７及び金属製枠体８１を介して蓋部材３５と接合されている上部単セル用隔離セパレータ３６を有する。
中間の単セルは、中間セパレータ３４３の上面に配設されたニッケルフェルト層５、基板となる燃料極２２、固体電解質層２１、空気極２３及びインコネル繊維メッシュ層６をこの順に備える。また、下面が固体電解質層２１及び金属製枠体８４と接合され、上面が絶縁性セラミックであるＭｇＯ−ＭｇＡｌ_２Ｏ_４焼結体からなる枠体７及び金属製枠体８３を介して中間セパレータ３４２と接合されている中間単セル用隔離セパレータ３９を有する。
下部の単セルは、底部材３７の上面に配設されたニッケルフェルト層５、基板となる燃料極２２、固体電解質層２１、空気極２３及びインコネル繊維メッシュ層６をこの順に備える。また、下面が固体電解質層２１及び金属製枠体８６と接合され、上面が枠体７及び金属製枠体８５を介して中間セパレータ３４３と接合されている下部単セル用隔離セパレータ３８を有する。
【００５２】
蓋部材３５、上部単セル用隔離セパレータ３６、下部単セル用隔離セパレータ３８、中間単セル用隔離セパレータ３９、中間セパレータ３４２、３４３、金属製枠体８１、８２、８３、８４、８５、８６及び底部材３７は、いずれもＳＵＳ４３０により形成されている。更に、蓋部材３５と金属製枠体８１、上部単セル用隔離セパレータ３６と金属製枠体８２、金属製枠体８２と中間セパレータ３４２、中間セパレータ３４２と金属製枠体８３、中間単セル用隔離セパレータ３９と金属製枠体８４、金属製枠体８４と中間セパレータ３４３、中間セパレータ３４３と金属製枠体８５、下部単セル用隔離セパレータ３８と金属製枠体８６、及び金属製枠体８６と底部材３７、はそれぞれＡｇ、Ｐｄ及び少量のＴｉを含有する接合材のうち、特に金属間の接合に適した組成の接合材により接合され、接合層１０が形成されている。
【００５３】
▲２▼燃料ガス導入管又は排出管、及び支燃性ガス導入管又は排出管
上部単セルにおいて、上部単セル用隔離セパレータ３６と中間セパレータ３４２との間に形成された空間には、上部単セルの燃料極２２に燃料ガスを導入するための燃料ガス導入管９１が開口している（図９参照）。また、この空間の燃料ガス導入管９１の開口部と対向する側には、上部単セルの燃料極２２から燃料ガスを排出するための燃料ガス排出管９２が開口している（図９参照）。更に、蓋部材３５と上部単セル用隔離セパレータ３６との間に形成された空間には、上部単セルの空気極２３に支燃性ガスを導入するための支燃性ガス導入管９３が開口している（図１０参照）。また、この空間の支燃性ガス導入管９３の開口部と対向する側には、上部単セルの空気極２３から支燃性ガスを排出するための支燃性ガス排出管９４が開口している（図１０参照）。
【００５４】
また、中間部単セルにおいて、中間部単セル用隔離セパレータ３９と中間セパレータ３４３との間に形成された空間には、中間部単セルの燃料極２２に燃料ガスを導入するための燃料ガス導入管９１が開口している（図９参照）。更に、この空間の燃料ガス導入管９１の開口部と対向する側には、上部単セルの燃料極２２から燃料ガスを排出するための燃料ガス排出管９２が開口している（図９参照）。また、中間セパレータ３４２と中間部単セル用隔離セパレータ３９との間に形成された空間には、中間部単セルの空気極２３に支燃性ガスを導入するための支燃性ガス導入管９３が開口している（図１０参照）。更に、この空間の支燃性ガス導入管９３の開口部と対向する側には、上部単セルの空気極２３から支燃性ガスを排出するための支燃性ガス排出管９４が開口している（図１０参照）。
【００５５】
更に、下部単セルにおいて、下部単セル用隔離セパレータ３８と底部材３７との間に形成された空間には、下部単セルの燃料極２２に燃料ガスを導入するための燃料ガス導入管９１が開口している（図９参照）。また、この空間の燃料ガス導入管９１の開口部と対向する側には、下部単セルの燃料極２２から燃料ガスを排出するための燃料ガス排出管９２が開口している（図９参照）。更に、中間セパレータ３４３と下部単セル用隔離セパレータ３８との間に形成された空間には、下部単セルの空気極２３に支燃性ガスを導入するための支燃性ガス導入管９３が開口している（図１０参照）。また、この空間の支燃性ガス導入管９３の開口部と対向する側には、下部単セルの空気極２３から支燃性ガスを排出するための支燃性ガス排出管９４が開口している（図１０参照）。
尚、この実施例５の燃料電池では、上部単セルの上面に更に他の単セルが積層された場合、蓋部材が中間セパレータとして機能することになる。更に、下部単セルの下面に更に他の単セルが積層された場合、底部材が中間セパレータとして機能することになる。
【００５６】
また、上部単セル、中間部単セル及び下部単セルの各々に燃料ガス又は支燃性ガスを導入し、又は排出するためのそれぞれの管は、本管に側管が取り付けられた構造であり、上部発電層、中間部発電層及び下部発電層に燃料ガス又は支燃性ガスが同時に導入され、且つ排出される。更に、燃料ガス導入管と燃料ガス排出管、及び支燃性ガス導入管と支燃性ガス排出管は、この実施例５の場合は、燃料ガス及び支燃性ガスがそれぞれ対向方向に流通するような位置に取り付けられている。これにより、上部発電層、中間部発電層及び下部発電層の各々の燃料極と燃料ガス、及び空気極と支燃性ガスをそれぞれ効率よく接触させることができる。
【００５７】
（２）燃料電池からの電力の取り出し
この平板型ＳＯＦＣスタックでは、上部単セルの燃料極２２は、ニッケルフェルト５を介して中間セパレータ３４２と電気的に接続されている。また、中間セパレータ３４２は、インコネル繊維メッシュ６を介して中間部単セルの空気極２３と電気的に接続されている。更に、中間部単セルの燃料極２２は、ニッケルフェルト５を介して中間セパレータ３４３と電気的に接続されている。また、中間セパレータ３４３は、インコネル繊維メッシュ６を介して下部単セルの空気極２３と電気的に接続されている。このように上部単セル、中間部単セル及び下部単セルは各々直列に接続されている。また、スタックを所定の作動温度に昇温させ、燃料ガス導入管９１に水素等の燃料ガスを導入して燃料極２２と接触させ、支燃性ガス導入管９３に空気等の支燃性ガスを導入して空気極２３と接触させることにより、燃料極２２と空気極２３との間に起電力が生じ、この電力を外部に取り出すことにより発電装置として機能させることができる。電力は、燃料極側においては下部単セルの下面に配設されたニッケルフェルト５を介して底部材３７に取り出され、空気極側においては上部単セルの上面に配設されたインコネル繊維メッシュ６を介して蓋部材３５に取り出され、蓋部材３５と底部材３７との間でスタック全体の電力を取り出すことができる。
【００５８】
（３）燃料電池の作用
この固体電解質型燃料電池では、３個の発電層がそれぞれ燃料極支持型であり、この構造の場合、７５０℃程度の作動温度でも電流を取り出すことができる。そのため、蓋部材、各種セパレータ、金属製枠体及び底部材を、セラミックではなくＳＵＳ４３０等のステンレス鋼により形成することができる。上部単セル、中間部単セル及び下部単セルのそれぞれにおいて、固体電解質層と隔離セパレータとは、上記［１］に記載の特定の接合材のうちの固体電解質層と金属との接合に適した接合材（例えば、実験例６の接合材）により、実験例６と同じ条件で強固に接合されている。
【００５９】
更に、上部単セル用隔離セパレータ３６と、絶縁性セラミックからなる枠体７の一面及び枠体７の他面と金属製枠体８１、中間部単セル用隔離セパレータ３９と、絶縁性セラミックからなる枠体７の一面及び枠体７の他面と金属製枠体８３、並びに下部単セル用隔離セパレータ３８と、絶縁性セラミックからなる枠体７の一面及び枠体７の他面と金属製枠体８５は、上記［１］に記載の特定の接合材のうちの絶縁性セラミックと金属との接合に適した接合材（例えば、実験例１４の接合材）により、実験例１４と同じ条件で強固に接合されている。また、蓋部材３５と金属製枠体８１、上部単セル用隔離セパレータ３６と金属製枠体８２、金属製枠体８２と中間セパレータ３４２、中間セパレータ３４２と金属製枠体８３、中間部単セル用隔離セパレータ３９と金属製枠体８４、金属製枠体８４と中間セパレータ３４３、中間セパレータ３４３と金属製枠体８５、下部単セル用隔離セパレータ３９と金属製枠体８６、及び金属製枠体８６と底部材３７は、上記［１］に記載の特定の接合材と同様の組成であり、金属間の接合に適した接合材により強固に接合されている。
このように各々の接合部はいずれもＡｇ、Ｐｄ及び少量のＴｉ等を含有する接合材により接合されており、それぞれの接合部においては圧縮応力が残留しているものと考えられ、種々の外力に耐えられる強靭なスタック構造を形成することができる。
【００６０】
［３］燃料ガス及び支燃性ガス
実施例３、実施例４及び実施例５の固体電解質型燃料電池を用いて発電させる場合、燃料極側には燃料ガスを導入し、空気極側には支燃性ガスを導入する。燃料ガスとしては、水素、水素源となる炭化水素、水素と炭化水素との混合ガス、及びこれらのガスを所定温度の水中を通過させ加湿した燃料ガス、これらのガスに水蒸気を混合させた燃料ガス等が挙げられる。炭化水素は特に限定されず、例えば、天然ガス、ナフサ、石炭ガス化ガス等が挙げられる。更に、メタン、エタン、プロパン、ブタン及びペンタン等の炭素数が１〜１０、好ましくは１〜７、より好ましくは１〜４の飽和炭化水素、並びにエチレン及びプロピレン等の不飽和炭化水素を主成分とするものが好ましく、飽和炭化水素を主成分とするものが更に好ましい。これらの燃料ガスは１種のみを用いてもよいし、２種以上を併用することもできる。また、５０体積％以下の窒素及びアルゴン等の不活性ガスを含有していてもよい。
【００６１】
支燃性ガスとしては、酸素と他の気体との混合ガス等が挙げられる。また、この混合ガスには８０体積％以下の窒素及びアルゴン等の不活性ガスが含有されていてもよい。これらの支燃性ガスのうちでは安全であって、且つ安価であるため空気（約８０体積％の窒素が含まれている。）が好ましい。
【００６２】
尚、本発明では上記の実施例に限られず、目的、用途等によって本発明の範囲内において種々変更した実施例とすることができる。例えば、発電層等の平面形状は、長方形、円形及び楕円形等とすることができ、同様の平面形状を有する固体電解質型燃料電池とすることができる。また、平板型ＳＯＦＣスタックでは、各種セパレータ等の金属成形体の間は溶接などの方法によっても接合することができる。しかし、例えば、図１１に従来の燃料電池として示す内部マニホールド型のスタックにおけるセパレータの周縁の貫通孔の内部は溶接では接合することができない。この場合に、前記［１］における特定の接合材を使用すれば、展延性に優れるＡｇによって貫通孔の周縁を十分に気密にシールすることができる。
【００６３】
更に、固体電解質層の形成に用いる材料はＳｃＳＺに限定されず、ＳＯＦＣの使用条件等により適宜選択することができる。この材料としては、例えば、ＺｒＯ_２系セラミック、ＬａＧａＯ_３系セラミック、ＢａＣｅＯ_３系セラミック、ＳｒＣｅＯ_３系セラミック、ＳｒＺｒＯ_３系セラミック及びＣａＺｒＯ_３系セラミック等が挙げられる。これらのセラミック系材料のうちでは、ＺｒＯ_２系セラミックが好ましく、Ｙ及び希土類元素のうちの少なくとも１種により安定化されたＺｒＯ_２系セラミックが好ましい。こられの安定化ジルコニアもＳｃＳＺと同様に優れたイオン伝導性及び機械的強度を有する。
尚、この固体電解質層の厚さは電気抵抗と強度とを勘案し、５〜１００μｍ、特に５〜５０μｍ、更には５〜３０μｍとすることができる。
【００６４】
また、燃料極の形成に用いる材料もＮｉ及びＳｃＳＺに限定されず、ＳＯＦＣの使用条件等により適宜選択することができる。この材料としては、例えば、Ｐｔ、Ａｕ、Ａｇ、Ｐｄ、Ｉｒ、Ｒｕ、Ｒｈ、Ｎｉ及びＦｅ等の金属が挙げられる。これらの金属は１種のみでもよいし、２種以上の金属の合金でもよい。また、これらの金属及び／又は合金と、Ｙ及び希土類元素のうちの少なくとも１種により安定化されたジルコニア等のジルコニア系セラミック、セリア系セラミック及び酸化マンガン等のセラミックとの混合物（サーメットを含む。）が挙げられる。更に、Ｎｉ及びＦｅ等の金属の酸化物と、上記セラミックのうちの少なくとも１種との混合物などが挙げられる。
また、燃料極の平面形状は特に限定されないが、固体電解質層及び空気極と同じ形状であることが好ましい。更に、燃料極と固体電解質層とは各々の全面で積層されていることが好ましい。
【００６５】
固体電解質型燃料電池において、各々の単セルが有する発電層は、強度の観点から過度に薄くすることは好ましくないが、発電性能の観点では前記のように固体電解質層を厚くすることは好ましくない。そのため、実施例４及び実施例５のように燃料極支持型とすることができ、この燃料極支持型では、燃料極は固体電解質層の２０倍以上の厚さであることが好ましい。２０倍未満であると発電層の機械的強度が不十分となる傾向にある。この燃料極の厚さは２００〜３０００μｍ、特に５００〜２０００μｍであることが好ましい。２００μｍ未満であると基板として有効に機能せず、３０００μｍを越えると、体積当たりの発電効率が低下する傾向にある。一方、空気極支持型とすることもでき、この場合は、燃料極の厚さは、１０〜５０μｍ、特に２０〜４０μｍであることが好ましい。この厚さが１０〜５０μｍであれば、電極として十分に機能し、５０μｍを越えて厚くする必要はない。
【００６６】
また、空気極の形成に用いる材料はＬａ_１−ｘＳｒ_ｘＭｎＯ_３系複合酸化物に限定されず、ＳＯＦＣの使用条件等により適宜選択することができる。この材料としては、例えば、Ｐｔ、Ａｕ、Ａｇ、Ｐｄ、Ｉｒ、Ｒｕ及びＲｈ等の金属が挙げられる。これらの金属は１種のみでもよいし、２種以上の金属の合金でもよい。また、Ｌａ、Ｓｒ、Ｃｅ、Ｃｏ及びＭｎ等の酸化物（例えば、Ｌａ_２Ｏ_３、ＳｒＯ、Ｃｅ_２Ｏ_３、Ｃｏ_２Ｏ_３、ＭｎＯ_２及びＦｅＯ等）が挙げられる。更に、Ｌａ、Ｓｒ、Ｃｅ、Ｃｏ及びＭｎ等のうちの少なくとも１種を含有する各種の複合酸化物（例えば、Ｌａ_１−ｘＳｒ_ｘＣｏＯ_３系複合酸化物、Ｌａ_１−ｘＳｒ_ｘＦｅＯ_３系複合酸化物、Ｌａ_１−ｘＳｒ_ｘＣｏ_１−ｙＦｅ_ｙＯ_３系複合酸化物、Ｐｒ_１−ｘＢａ_ｘＣｏＯ_３系複合酸化物及びＳｍ_１−ｘＳｒ_ｘＣｏＯ_３系複合酸化物等）が挙げられる。
【００６７】
これらの材料のうちでは、複合酸化物が好ましく、更にはＬｎ_１−ｘＭ_ｘＣｏＯ_３系複合酸化物（但し、Ｌｎは希土類元素であり、ＭはＳｒ又はＢａである。）をＣｅＯ_２系酸化物による反応防止層と組み合わせて用いることが好ましい。このＬｎ_１−ｘＭ_ｘＣｏＯ_３系複合酸化物においてＬｎ及びＭが更に他の元素により置換されていてもよい。これらのＬｎ_１−ｘＭ_ｘＣｏＯ_３系複合酸化物のうちでは、組成式Ｌｎ_１−ｘＭ_ｘＣｏＯ_{3 ±δ}で表され、０．２≦ｘ≦０．８、且つ、０≦δ＜１（δは酸素過剰量又は酸素欠損量を表す。）であるものが特に好ましく、ＬｎがＬａ、Ｐｒ及びＳｍのうちの少なくとも１種であるものが更に好ましい。このようなＬｎ_１−ｘＭ_ｘＣｏＯ_３系複合酸化物としては、例えば、Ｌａ_０．６Ｓｒ_０．４ＣｏＯ_{3 ±δ}、Ｐｒ_０．５Ｂａ_０．５ＣｏＯ_{3 ±δ}及びＳｍ_０．５Ｓｒ_０．５ＣｏＯ_{3 ±δ}等が挙げられる。
【００６８】
更に、この空気極の平面形状は特に限定されないが、固体電解質層及び燃料極と同じ形状であることが好ましい。更に、その平面方向の寸法は、燃料電池の構造によっては、固体電解質層及び燃料極と同じにすることもできる。また、隔離セパレータが固体電解質層の一表面の周縁に接合される場合は、空気極は固体電解質層及び燃料極より小さく形成される。この空気極と固体電解質層とは各々の全面で積層されていることが好ましい。
【００６９】
空気極は、前記のように発電層の強度を支持する基板として形成されることがある。空気極支持型である場合は、空気極の厚さは固体電解質層の２０倍以上の厚さであることが好ましい。２０倍未満であると発電層の機械的強度が不十分となる傾向にある。この空気極の厚さは２００〜３０００μｍ、特に５００〜２０００μｍであることが好ましい。２００μｍ未満であると基板として有効に機能せず、３０００μｍを越えると、体積当たりの発電効率が低下する傾向にある。一方、燃料極支持型である場合は、空気極の厚さは１０〜１００μｍ、特に２０〜５０μｍであることが好ましい。１０μｍ未満であると電極として十分に機能しないことがあり、１００μｍを越えると固体電解質層から剥離することがある。
【図面の簡単な説明】
【図１】本発明の積層体の断面を示す模式図である。
【図２】接合部を構成する複数の層の一例を模式的に示す説明図である。
【図３】接合材に含有されるＴｉ量と接合強度との関係を示すグラフである。
【図４】本発明の燃料電池の一例（実施例３）の断面を示す模式図である。
【図５】本発明の燃料電池の他例（実施例４）の外観を示す斜視図である。
【図６】図５の燃料電池のＡ−Ａ断面を示す模式図である。
【図７】図５の燃料電池のＢ−Ｂ断面を示す模式図である。
【図８】本発明の燃料電池の更に他例（実施例５）の外観を示す斜視図である。
【図９】図８の燃料電池のＡ−Ａ断面を示す模式図である。
【図１０】図８の燃料電池のＢ−Ｂ断面を示す模式図である。
【図１１】従来の内部マニホールド型の燃料電池の一例を分解して模式的に示す斜視図である。
【符号の説明】
１；積層体、１１；セラミック成形体、１２；ステンレス鋼成形体、１３；接合部、１３１、１３２；Ｔｉ偏析層、１３３；ＴｉとＡｇ及びＰｄとの反応層で、所定量のＴｉが含有されている層、１３４；Ｔｉ、Ａｇ及びＰｄを含有し、Ａｇの含有量が多い層、１３５；ＴｉとＡｇ及びＰｄとの反応層で、１３３の層よりＴｉが少ない層、１３６；ＡｇとＰｄとを含有する層、１００、１００’；平板型ＳＯＦＣスタック、２１；固体電解質層、２２；燃料極、２３；空気極、３１；積層用セパレータ、３２；上部セパレータ、３３；下部セパレータ、３４１、３４２、３４３；中間セパレータ、３５；蓋部材、３６；上部単セル用隔離セパレータ、３６１、３６２；貫通孔、３７；底部材、３８；下部単セル用隔離セパレータ、３８１、３８２；貫通孔、３９；中間単セル用隔離セパレータ、４１；燃料ガスの流路、４２；支燃性ガスの流路、５；ニッケルフェルト層、６；インコネル繊維メッシュ層、７；枠体、８１、８２、８３、８４、８５、８６；金属製枠体、９１；燃料ガス導入管、９２；燃料ガス排気管、９３；支燃性ガス導入管、９４；支燃性ガス排気管、１０；接合層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminate and a solid oxide fuel cell. More specifically, in a fuel cell in which a ceramic body and a heat-resistant alloy compact are joined by a joining material containing Ag and Pd, and a fuel cell in which a plurality of single cells are laminated, a solid electrolyte layer, The present invention relates to a solid oxide fuel cell in which a separator and the like are joined by a joining material containing Ag and Pd.
[0002]
[Prior art]
A flat plate type solid oxide fuel cell (hereinafter also referred to as “flat plate SOFC stack”) is formed by laminating a plurality of single cells. The flat plate SOFC stack includes an internal manifold type (see, for example, Patent Document 1) having a gas passage inside the stack and an external manifold type having a gas passage outside the stack.
[0003]
Patent Document 1 discloses an example of a flat plate-type SOFC stack as shown in FIG. This flat plate type SOFC stack is formed by laminating a plurality of single cells 4A via separators 5A made of a lanthanum chromite complex oxide or a refractory metal. Each single cell 4A includes a solid electrolyte layer 41A made of yttria-stabilized zirconia (YSZ), a fuel electrode made of Ni and YSZ, provided on one side of the solid electrolyte layer 41A, and provided on the other side. And an air electrode made of a perovskite complex oxide such as knight. In addition, through holes 22A for gas flow are formed in the four corners of the solid electrolyte layer 41A and the separator 5A, which serve as flow paths for flowing gas into and out of the fuel electrode and air electrode of the single cell 4A, respectively. ing. The solid electrolyte layer 41A and the separator 5A are hermetically sealed with a glassy sealing material.
[0004]
Further, in recent years, research has been actively conducted to operate the SOFC in a relatively low temperature range of 800 ° C. or lower by reducing the internal resistance by making the solid electrolyte layer such as YSZ as thin as possible. In this case, an inexpensive metal separator can be used and is attracting attention. In particular, if cheaper stainless steel can be used, the cost can be greatly reduced. However, when a glassy gas seal material is used, the reliability of the joint may be lowered. In order to improve this reliability, a sealing material that is mainly composed of Ag is used for the hermetic seal portion between the solid electrolyte layer of the oxygen production apparatus and the separator made of stainless steel, which is not an SOFC, but has similar operating conditions. A method of joining in a temperature range below the melting point of Ag has been proposed (see, for example, Patent Document 2).
[0005]
[Patent Document 1]
JP-A-10-199554
[Patent Document 2]
JP 2002-20180 A
[0006]
[Problems to be solved by the invention]
However, the flat SOFC stack described in Patent Document 1 has the following problems.
(1) When a hole is formed in a ceramic layer having poor workability, the yield is low and the cost is high.
(2) The mechanical strength of the ceramic layer is greatly reduced by drilling.
(3) When a glassy sealing material is used and a lanthanum chromite complex oxide is used as a separator, both are brittle and may be damaged by thermal stress or the like.
[0007]
Further, in the case of the oxygen production apparatus described in Patent Document 2, it is necessary to have a peelability that allows the deteriorated electrolyte tube to be easily replaced at the hermetic seal portion with stainless steel. Therefore, it joins in the temperature range below melting | fusing point of Ag so that it may not join firmly so that it cannot peel. On the other hand, in an apparatus in which flammable gas and oxygen are in contact with each other at a high temperature, such as SOFC, it is necessary to form a strong joint that does not easily peel off, and it is preferable to join at a temperature exceeding the melting point of Ag. Thus, the purpose of the oxygen production apparatus and the SOFC are completely different even when a sealing material mainly composed of Ag is used.
[0008]
This invention is made | formed in view of said situation, and it aims at providing the laminated body formed by joining a ceramic molded object and a heat-resistant alloy molded object with the joining material containing Ag and Pd. . It is another object of the present invention to provide a solid oxide fuel cell in which a plurality of single cells and the like are formed by being laminated, and a solid electrolyte layer and a separator are joined by a joining material containing Ag and Pd. .
[0009]
[Means for Solving the Problems]
The present invention is as follows.
1. A laminated body in which a ceramic molded body and a heat-resistant alloy molded body are bonded together by a bonding material, wherein the bonding material contains Ag and Pd.
2. The bonding material further contains Ti, and when the total of the Ag, the Pd, and the Ti is 100% by mass, the Ti content is 0.05 to 10% by mass. The laminated body as described in.
3. The bonding temperature is not less than the solid phase temperature of the bonding material and not more than 50 ° C. above the liquid phase temperature of the bonding material. Or 2. The laminated body as described in.
4). The ceramic molded body is a molded body made of stabilized zirconia. To 3. The laminated body in any one of.
5. The ceramic compact is made of MgO and MgAlO.₄1. A molded body made of ceramic containing To 4. The laminated body in any one of.
6). Above 1. To 5. A solid oxide fuel cell comprising a structural part comprising the laminate according to any one of the above.
7). In a solid oxide fuel cell having a structure in which a plurality of power generation layers are laminated via isolation separators made of a heat-resistant alloy, each power generation layer includes a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, And an air electrode provided on the other surface, the separator is partially joined to each solid electrolyte layer of the adjacent power generation layer, and for introducing the fuel gas into the fuel electrode of one power generation layer A flow path and a flow path for introducing a combustion-supporting gas into the air electrode of the other power generation layer, and each solid electrolyte layer and the separator separator are bonded by a bonding material containing Ag and Pd. A solid oxide fuel cell.
8). In a solid oxide fuel cell having a structure in which a plurality of single cells are stacked via an intermediate separator, each single cell is provided on a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, and on the other surface. A power generation layer having an air electrode provided, a part of which is joined to the solid electrolyte layer, and a flow path for introducing a fuel gas into the fuel electrode, and a combustion-supporting gas into the air electrode A separator made of a heat-resistant alloy that separates the flow path, and a frame made of an insulating ceramic is disposed between at least a part of the intermediate separator and the separator, and at least each of the solid electrolyte layers, The isolation separator is joined by a joining material containing Ag and Pd, respectively, and is a solid oxide fuel cell.
9. At least a part of the intermediate separator and the isolation separator, and the frame body are bonded together by a bonding material containing Ag and Pd, respectively. A solid oxide fuel cell according to 1.
10. The insulating ceramic is MgO and MgAl.₂O₄Including the above. Or 9. A solid oxide fuel cell according to 1.
11 The bonding material further contains Ti, and when the total of the Ag, the Pd, and the Ti is 100% by mass, the Ti content is 0.05 to 10% by mass. To 10. The solid oxide fuel cell according to any one of the above.
12 6. The bonding temperature is not less than the solid phase temperature of the bonding material and not more than 50 ° C. above the liquidus temperature. To 11. The solid oxide fuel cell according to any one of the above.
[0010]
【The invention's effect】
In the laminated body of the present invention, by using a specific bonding material, the ceramic molded body and the heat-resistant alloy molded body can be firmly bonded, and a decrease in strength due to thermal stress or the like can be suppressed.
Further, when the bonding material further contains Ti and the total of Ag, Pd and Ti is 100% by mass, and the Ti content is 0.05 to 10% by mass, the ceramic molded body and the heat-resistant alloy The molded body can be bonded more firmly and does not peel off.
Furthermore, when the bonding temperature is not lower than the solidus temperature of the bonding material and not higher than 50 ° C. above the liquidus temperature, the ceramic molded body and the heat-resistant alloy molded body are particularly strongly bonded. Can be peeled off.
Further, the ceramic molded body is a molded body made of stabilized zirconia or MgO and MgAl.₂O₄Can be firmly joined to the ceramic molded body and the heat-resistant alloy molded body.
In the solid oxide fuel cell of the present invention, the gas seal portion is firmly joined, and the strength reduction due to thermal stress or the like can be suppressed, so that good power generation efficiency is maintained over a long period of time.
The frame made of insulating ceramic is made of MgO and MgAl.₂O₄In the case where the frame body and the separator are included, the frame body and the separator or the like can be more sufficiently brought into close contact with each other.
Furthermore, when the bonding material further contains Ti and the total amount of Ag, Pd and Ti is 100% by mass, and the Ti content is 0.05 to 10% by mass, the solid electrolyte layer and the separator, etc. Can be joined more firmly.
In addition, when the bonding temperature is equal to or higher than the solid phase temperature of the bonding material and equal to or lower than the temperature exceeding the liquid phase temperature of 50 ° C., the solid electrolyte layer and the separator can be bonded particularly firmly, There is no peeling.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[1] Laminated body of ceramic molded body and heat-resistant alloy molded body
The “laminated body” is obtained by bonding a ceramic molded body and a heat-resistant alloy molded body with a specific bonding material. As shown in FIG. 1, the laminate 1 is obtained by joining a ceramic molded body 11 and a heat-resistant alloy molded body 12 via a joint portion 13.
(1) Ceramic molded body
The ceramic constituting the “ceramic molded body” is not particularly limited, and examples thereof include oxide ceramics, nitride ceramics, carbide ceramics, and silicide ceramics. Examples of the oxide ceramic include zirconia, magnesia, spinel, alumina, titania and the like. Moreover, the ceramic which consists of complex oxide containing 2 or more types of elements is mentioned. Examples of the nitride ceramic include silicon nitride, titanium nitride, and boron nitride. Examples of the carbide ceramic include silicon carbide and tungsten carbide. Examples of the silicide ceramic include molybdenum silicide. These ceramics can be selected depending on the use of the laminate.
[0012]
(2) Heat-resistant alloy compact
The heat-resistant alloy constituting the “heat-resistant alloy compact” is not particularly limited, and examples include stainless steel, nickel-based alloy, and chromium-based alloy. Examples of the stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS430, SUS434, and SUS405. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305. Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. As the chromium-based alloy, Ducrloy CRF (94Cr5Fe1Y₂O₃) And the like. These various heat-resistant alloys can be selected depending on the use of the laminate.
[0013]
(3) Bonding material
The “joining material” contains Ag and Pd. The content of each of the “Ag” and the “Pd” in the bonding material is not particularly limited, but when the total of Ag and Pd is 100 mass%, the Ag content is 90 to 98 mass%, particularly It is preferable that it is 93-97 mass% and content of Pd is 2-10 mass%, especially 3-7 mass%. When the Ag content exceeds 98% by mass, that is, when the Pd content is less than 2% by mass, the oxidation resistance and the like of the bonding material is lowered, and a joining portion having sufficient durability is formed. May not be possible. On the other hand, when the content of Ag is less than 90% by mass, that is, when the content of Pd exceeds 10% by mass, the bonding material does not flow sufficiently during bonding, and the sealing performance of the bonded portion tends to decrease. is there.
[0014]
The bonding material may further contain Cu. The content of each of Ag, Pd and Cu when Cu is contained is not particularly limited, but when the total of Ag, Pd and Cu is 100% by mass, the content of Ag is 45 to 65% by mass. In particular, it is preferable that the content of Pd is 50 to 60% by mass, the content of Pd is 15 to 35% by mass, particularly 20 to 30% by mass, and the content of Cu is 10 to 30% by mass, and particularly 15 to 25% by mass. When Cu is contained, even if it contains a larger amount of Pd than a bonding material that does not contain Cu, it has sufficient fluidity and maintains excellent sealing performance. On the other hand, when the total of Ag and Cu is less than 65% by mass, that is, when the content of Pd exceeds 35% by mass, the fluidity is lowered and the sealing property tends to be insufficient.
[0015]
The bonding material may further contain Ti. By containing an appropriate amount of Ti, particularly high bonding strength can be obtained even when the bonding temperature is relatively low. The content of Ti is when the total of Ag, Pd and Ti is 100% by mass, or when Cu is contained, the total of Ag, Pd, Cu and Ti is 100% by mass. , 0.05 to 10% by mass, preferably 0.05 to 8% by mass, and more preferably 0.05 to 6% by mass. When the Ti content is 0.05 to 10% by mass, a bonding portion having practically sufficient strength can be formed even if the bonding atmosphere is not a vacuum but an inert atmosphere such as argon. . When the bonding atmosphere is vacuum, the Ti content can be 0.05 to 20% by mass, particularly 0.05 to 15% by mass, and the Ti content is 0.08 to If it is 10% by mass, the bonding strength is greatly improved, and at the time of measuring the bonding strength, there is a case where the ceramic constituting the ceramic molded body does not coherently break, rather than the interface peeling at the bonding surface. For example, ceramic is YSZ and MgO-MgAl.₂O₄In this case, a large bonding strength (ceramic fracture) of 200 MPa or more can be obtained.
[0016]
The bonding material containing Ag, Pd, Cu, and Ti is usually 20 × 10.^-6(10-11.5) × 10 of zirconia-based or ceria-based ceramics having a coefficient of thermal expansion of at least / ° C.^-6/ 12 ° C. and (12-17) × 10 of stainless steel which is a heat resistant alloy^-6It is very different from / ℃. However, since Ag having excellent flexibility relaxes the stress due to the difference in thermal expansion coefficient, stable and sufficient sealing performance and bonding strength are maintained.
[0017]
The bonding material may contain other components in addition to Ag, Pd, Cu, and Ti as long as the bonding strength, gas sealability, and the like are not deteriorated. Examples of such components include Sn, In, Ni, and Nb. These other components are the sum of Ag and Pd, and in the case of containing Cu, the sum of Ag, Pd and Cu, and in the case of containing Ti, the sum of Ag, Pd and Ti, or Ag, Pd, Cu. And when the total of Ti is 100 mass parts, it is 10 mass parts or less, Especially 0.1-10 mass parts, Furthermore, 0.5-5 mass parts can be contained.
[0018]
(4) Structure of joint
When the bonding material contains Ti, oxide-based ceramics, in particular, a molded body made of a YSZ sintered body, a ScSZ sintered body, and the like, and a heat-resistant alloy molded body, are bonded between the respective molded bodies. It has a plurality of layers having different compositions. Specifically, when a stainless steel molded body is used as the heat-resistant alloy molded body, the joint 13 extends from the molded body side made of oxide ceramic to the stainless steel molded body side. (1) Ti segregation layer 131, {circle around (2)} In the reaction layer of mainly Ti, Pd and a small amount of Fe and Ag, when the total amount of Ti, Ag, Pd and Fe is 100% by mass, Ti is 30 to 60% by mass, particularly 40 to 40%. The layer 133 containing 60% by mass, (3) Ti, Ag and Pd are contained, and when the total of these is 100% by mass, the Ag content is 95% by mass or more, particularly 98% by mass or more ( In the case of layer 134, (4) mainly a reaction layer of Ti, Pd, and a small amount of Fe and Ag, the total of Ti, Ag, Pd and Fe is 100% by mass. 15 to 40% by weight, especially 20 Are contained 30 wt%, have the above-disclosed ▲ 2 ▼ layer 135 Ti is smaller than the. Further, when SUS430 is used as the stainless steel, as shown in FIG. 2, following the reaction layer (4), (5) Ti segregation layer 132, and (6) layer 136 containing Ag, Pd and Fe, Is formed. Depending on the type of the refractory metal, a layer having a composition different from that of the layers (5) and (6) may be formed at positions corresponding to the layers (5) and (6).
[0019]
Further, each of the Ti segregation layers of (1) and (5) contains oxygen moved from a molded body made of an oxide-based ceramic or oxygen mixed from the bonding atmosphere. Furthermore, a larger amount of oxygen is detected in each of layers (1) to (6) than the heat-resistant alloy. The oxygen content in the Ti segregation layer is small if Ti contained in the bonding material is 10% by mass or less, and the bonding strength does not decrease. On the other hand, when Ti contained in the bonding material exceeds 10% by mass, the Ti segregation layer has TiO.₂Oxygen is generated so as to be generated, and this may cause easy separation between the Ti segregation layer and the molded body made of the oxide ceramic. Furthermore, if the Ti contained in the bonding material is excessive, it is presumed that the liquidus temperature of the bonding material increases and the fluidity decreases, and this also greatly decreases the bonding strength.
[0020]
Further, the composition of each layer constituting the joint varies depending on the kind of the heat-resistant alloy, but by joining at a temperature equal to or higher than the solidus temperature of the joining material, at least a plurality of (1) to (4) are provided. A joining portion composed of layers is formed, and the ceramic compact and the heat-resistant alloy compact are firmly joined. Further, when the ceramic is magnesia, spinel, alumina, or a mixture thereof, trace amounts of Mg and Al are also detected in each layer, but the joint is basically the above-described (1) to (4). Each layer is formed by a corresponding layer. The layers (5) and (6) may be formed or may not be formed.
In addition, each layer of (1) to (6) can be confirmed by, for example, observing the cross section of the joint portion with an X-ray microanalyzer or the like.
[0021]
Further, when the bonding material does not contain Ti, a bonding portion composed of a plurality of layers as described above is not formed, but can be firmly bonded similarly. In this case, a Ti segregation layer is not observed in the vicinity of the interface between the ceramic molded body and the joint, but the liquid phase of the joining material becomes ceramic by joining at a temperature equal to or higher than the solidus temperature as shown in (5) below. It is inferred that these fine indentations and residual pores penetrate and are firmly joined by the anchor effect. On the other hand, on the heat-resistant alloy formed body side, it has been confirmed that the content of Pd contained in the joining material in the vicinity of the interface is reduced after joining as compared with that before joining. From this, it is inferred that Pd contained in the bonding material diffuses toward the heat-resistant alloy formed body to form some kind of reaction layer, which is considered to be firmly bonded. Therefore, it is preferable to bond at a temperature equal to or higher than the solidus temperature of the bonding material and sufficiently diffuse Pd to form a stronger bonded portion.
[0022]
(5) Joining temperature
The temperature at which the ceramic molded body and the heat-resistant alloy molded body are bonded using the bonding material is not particularly limited, but it should be not lower than the solid phase temperature of the bonding material and not higher than the liquid phase temperature of 50 ° C. Is preferred. Although the melting point of Ag is about 962 ° C., if bonding is performed at a temperature equal to or higher than the solidus temperature of the bonding material, the bonding material component containing Ag is melted, and Ag having high extensibility becomes a ceramic molded body and a heat-resistant alloy molded body It flows sufficiently between the two and can be brought into close contact with each other. In particular, when bonding is performed at a temperature exceeding the liquidus temperature of the bonding material, more stable and sufficient sealing properties and bonding strength are maintained, and they do not easily peel off. On the other hand, it is not necessary for the bonding temperature to be higher than the liquidus temperature exceeding 50 ° C. If bonding is performed at a temperature higher than the solidus temperature and lower than a temperature exceeding 50 ° C, a sufficient seal can be obtained. And bonding strength can be obtained.
[0023]
(6) Joining atmosphere
The atmosphere at the time of bonding is not particularly limited as long as it is an inert atmosphere, and can be a vacuum and an inert gas atmosphere such as argon, nitrogen, or the like. The bonding atmosphere is particularly preferably a vacuum, and the bonding strength can be greatly improved in a vacuum atmosphere. The degree of vacuum is 10 Pa or less, particularly 1 × 10.^-2˜1 Pa is preferable.
[0024]
[2] Solid oxide fuel cell
A solid oxide fuel cell is formed by laminating a plurality of single cells or the like. Each single cell includes a power generation layer, and each power generation layer includes a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, and an air electrode provided on the other surface. Further, each single cell or the like depends on the structure of the fuel cell, but the above-mentioned “separation separator” for isolating the flow path of the fuel gas and the flow path of the combustion-supporting gas or between each single cell. They are stacked via the “intermediate separator” provided. These other separators such as the separator, the intermediate separator, the lid member, and the bottom member are all made of a heat-resistant metal such as stainless steel. Further, in order to electrically insulate the power generation layers of each single cell, the “frame” made of an insulating ceramic is laminated at a predetermined portion in the laminating direction to prevent a short circuit. In the solid oxide fuel cell of the present invention, the solid electrolyte layer and the separator are joined by the joining material described in [1] above, and other separators, intermediate separators, frames, lid members, bottom members, etc. The structural members are also joined directly or indirectly by the joining material described in [1].
[0025]
The above-mentioned “solid electrolyte layer” has ion conductivity capable of moving a part of one of the fuel gas introduced into the fuel electrode or the combustion-supporting gas introduced into the air electrode during the operation of the battery as ions. Have. Although what kind of ion can be conducted is not particularly limited, examples of the ion include oxygen ion and hydrogen ion. Further, the “fuel electrode” is in contact with a fuel gas serving as a hydrogen source and functions as a negative electrode in the SOFC. Further, the “air electrode” is in contact with a combustion-supporting gas serving as an oxygen source and functions as a positive electrode in the SOFC.
[0026]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
[1] YSZ sintered body or MgO-MgAl₂O₄Evaluation of bonding strength between sintered body and SUS430
Example 1 (joining of YSZ sintered body and SUS430)
A solid electrolyte of SOFC using a bonding material containing Ag as a main component and containing Pd, or a bonding material containing Ag as a main component and containing Pd and Cu, and a bonding material containing a specific amount of Ti in these bonding materials. A YSZ sintered body often used as a layer and a heat-resistant metal often used as a separator or the like were joined, and the joining strength was evaluated. As the heat-resistant metal, SUS430, which is a ferritic stainless steel, was used.
[0027]
Comparative Experimental Example 1 and Experimental Examples 1-12
(1) Joined material and bonding material
The YSZ sintered body was produced by forming a raw material powder and firing it by a conventional method. A 15 × 15 × 20 mm sufficiently densified rectangular parallelepiped sintered body was obtained and used for the production of a test piece. Further, a SUS430 steel plate having a thickness of 0.3 mm was cut into 15 × 15 mm, and this was used for preparing a test piece. The bonding material is a sheet having a thickness of 50 μm, and (a) a material containing 95% by mass of Ag and 5% by mass of Pd (solidus temperature is 970 ° C., liquidus temperature is 1010 ° C. And (b) 54 mass% Ag, 25 mass% Pd and 21 mass% Cu (the solidus temperature is 900 ° C. and the liquidus temperature is 950 ° C.) It was used. Further, by using a Ti foil laminated on the bonding material of (a) and (b) as described below at the time of bonding, the total amount with the bonding material of (a) is 0.1% by mass, 2% by mass, The joints containing 5% by mass and 10% by mass of Ti (the solidus temperature of the joining material containing 0.1% by mass, 2% by mass, 5% by mass and 10% by mass of Ti are both about 970 And the liquidus temperature is about 1010 ° C., about 1010 ° C., about 1020 ° C., and about 1030 ° C.), respectively, and (b) the joint material contains 2% by mass of Ti. The joining was performed so that a joining part (the solid phase temperature of the joining material containing 2 mass% Ti was about 900 ° C. and the liquid phase temperature was about 950 ° C.) was formed. For comparison, a commercially available crystallized glass paste (glass composition; 43 mass% BaO / 33 mass% SiO₂/ 15 mass% ZnO / 6 mass% Al₂O₃/ 2 mass% ZrO₂/ 1 mass% CaO) was used.
[0028]
(2) Formation of laminate
The YSZ sintered body is vertically placed so that the 15 × 15 mm surface is the upper surface. In the case of Experimental Examples 1 to 3 in Table 1, two pieces of the bonding material (a) cut to 15 × 15 mm are placed on this surface. Then, one SUS430 steel plate is placed on the joining material, two joining materials (a) are placed on the SUS430 steel plate, and another YSZ sintered body is placed on the joining material at 15 × 15 mm. It was placed so that the surface of Then, on the upper surface of the upper YSZ sintered body, a weight whose main component is 500 g of tungsten (content: 95% by mass) is placed on the upper surface of the YSZ sintered body so that each member does not deviate from each other. It accommodated in the atmosphere control heat treatment furnace, it hold | maintained and bonded for 30 minutes at the predetermined temperature of Table 1 in the vacuum atmosphere (1 Pa or less) or argon atmosphere, and the laminated body was produced. The temperature raising / lowering speed was 500 ° C./hour.
[0029]
Further, in Experimental Examples 4 to 9 in Table 1, a pure Ti foil having a thickness of 10 μm was cut between each of the two bonding materials (a) in the case of Experimental Examples 1 to 3 to have a predetermined mass. A laminated body was produced in the same manner as in Experimental Examples 1 to 3 except that the substrate was placed. In Experimental Examples 10 to 11, laminates were produced in the same manner as in Experimental Examples 1 to 3, except that the bonding material (b) was used. Furthermore, in Experimental Example 12, except that a pure Ti foil having a thickness of 10 μm cut so as to have a predetermined mass was placed between the two bonding materials (b) in the case of Experimental Examples 10 to 11, Laminates were produced in the same manner as in Experimental Examples 10-11. In Comparative Experimental Example 1, the crystallized glass paste was applied to both surfaces to be joined of the YSZ sintered body and the SUS430 steel plate, and was stored in an argon atmosphere heat treatment furnace and held at 1050 ° C. for 1 hour for heat treatment. The laminated body was produced like experiment example 1-3 except having performed. In Comparative Experimental Example 1, the temperature raising / lowering rate was 200 ° C./hour.
[0030]
(3) Preparation of test piece and measurement of bonding strength
Each of the laminates of Comparative Experimental Example 1 and Experimental Examples 1 to 12 produced in (2) was cut in the direction perpendicular to the joint surface, and four pieces having dimensions of 7.5 × 7.5 × 40 mm were obtained. A rod-shaped body was used. Then, the side surface of the rod-shaped body was polished according to JIS R 1624 to obtain a 6 × 6 × 40 mm test piece, and the bonding strength was measured by a four-point bending method. The results are also shown in Table 1 as average values of four test pieces.
[0031]
(4) Structure of joint
In the laminate of Experimental Example 6, the cross section of the joint between the YSZ sintered body and SUS430 was observed with an X-ray microanalyzer. As a result, it was found that the joint had a plurality of layers having different compositions between the YSZ sintered body and SUS430. Specifically, the plurality of layers are, from the YSZ sintered body side, (1) a Ti segregation layer, (2) a reaction layer of mainly Ti, Pd, and a small amount of Fe and Ag, Ti, Ag, Pd. When the total of Fe and Fe is 100% by mass, a layer containing 53% by mass of Ti, (3) Ti, Ag and Pd are contained, and when the total of these is 100% by mass, In a layer having a content of 98% by mass and (4) a reaction layer of mainly Ti, Pd and a small amount of Fe and Ag, when the total of Ti, Ag, Pd and Fe is 100% by mass, Ti is It was found that it was contained in an amount of 25% by mass and was a layer having less Ti as compared with the above (2). Further, following (4), it was confirmed that (5) Ti segregation layer and (6) Ag, Pd and Fe-containing layer were further formed.
[0032]
Example 2 (MgO-MgAl₂O₄(Bonding of sintered body and SUS430)
Comparative Experimental Example 2 and Experimental Examples 13-20
As a ceramic sintered body, instead of YSZ sintered body, MgO-MgAl₂O₄A laminated body was formed in the same manner as in Example 1 except that the sintered body was used, test pieces were prepared in the same manner, and the bonding strength was measured. MgO-MgAl₂O₄As raw material powder of the sintered body, 70% by mass of MgO powder and 30% by mass of MgAl₂O₄Using a mixed powder with the powder, it was molded by a conventional method and fired to produce a sintered body. The production method of the laminate and the test piece is the same as in Example 1, and the details of the used bonding material, bonding temperature, and bonding atmosphere are shown in Table 1. Moreover, the measurement results of the bonding strength are also shown in Table 1. In the laminate of Experimental Example 16, MgO—MgAl₂O₄As a result of observing the cross section of the bonded portion of the sintered body and SUS430 with an X-ray microanalyzer, it has a plurality of layers having different compositions similar to (1) to (5) in Experimental Example 6. I understood.
[0033]
[Table 1]

[0034]
According to the results in Table 1, it can be seen that, in the case of joining the YSZ sintered body of Example 1 and SUS430, in Comparative Experimental Example 1 using the crystallized glass paste, the joining strength is as low as 48 MPa. On the other hand, in Experimental Examples 1 to 3 using the bonding material (a) containing Ag as a main component and containing Pd, the bonding strength is 125 to 191 MPa, and the experiment using the bonding material (b) further containing Cu. In Examples 10 to 11, it can be seen that the bonding strength is 102 to 128 MPa, and any of those that change depending on the bonding temperature is sufficient. Furthermore, in Experimental Examples 4 to 9 and 12 in which the bonding material contains an appropriate amount (0.1 to 10% by mass) of Ti, the bonding strength is 132 to 230 MPa (In Experimental Examples 4 to 6 and 8, the YSZ sintered body is broken. It can be seen that this is superior particularly when the bonding atmosphere is a vacuum. Further, in Experimental Example 4, the Ti content is as small as 0.1% by mass, but even with such a very small amount of Ti, the bonding strength cannot be predicted as compared with Experimental Example 2 that does not contain Ti. It can be seen that there is a significant improvement. Further, in Experimental Examples 8 and 9 where the Ti content is as large as 10% by mass, in Experimental Example 9 in which the bonding atmosphere is argon, the effect of containing Ti tends to be insufficient. On the other hand, in Experimental Example 8 in which the bonding atmosphere is vacuum, the YSZ sintered body is firmly bonded so as to be broken, and it is understood that bonding in a vacuum atmosphere is more preferable.
[0035]
MgO-MgAl of Example 2₂O₄In the case of bonding between the sintered body and SUS430, in Comparative Experimental Example 2 using the crystallized glass paste, the bonded body was peeled off during grinding, and the bonding strength could not be measured. On the other hand, in Experimental Example 13 using a bonding material (a) containing Ag as a main component and containing Pd, and in Experimental Example 19 using a bonding material (b) containing Cu, the bonding strength is 67 to 78 MPa. It can be seen that the strength is sufficient. In Experimental Examples 14 to 18 and 20, in which the bonding material contains an appropriate amount (0.1 to 10% by mass) of Ti, the bonding strength is 132 to 256 MPa (In Experimental Examples 16 and 18, MgO—MgAl).₂O₄The sintered body broke down. The joint strength was greatly improved by containing Ti. In particular, Experimental Example 14 has a Ti content as low as 0.1% by mass, but even with such a small amount of Ti, the bonding strength cannot be predicted as compared with Experimental Example 13 that does not contain Ti. It can be seen that there is a significant improvement. Furthermore, this MgO-MgAl₂O₄Also in the case of a sintered body, as can be seen by comparing Experimental Examples 16 and 17, the strength is greatly improved by bonding in a vacuum atmosphere.
[0036]
Experimental Examples 2, 4 to 6 and 8 (in the case of YSZ sintered body) and Experimental Examples 13, 14 to 16 and 18 (MgO—MgAl)₂O₄The relationship between the amount of Ti contained in the bonding material and the bonding strength in each case (in the case of a sintered body) is shown in FIG. According to FIG. 3, it can be seen that the bonding strength is greatly improved by a very small amount of Ti of 0.1% by mass. Further, in the case of the YSZ sintered body, the YSZ sintered body is broken when the Ti content is in the range of 0.1 to 10% by mass, and the strength is slightly improved as the Ti content is increased. MgO-MgAl₂O₄In the case of a sintered body, the bonding strength becomes maximum when the Ti content is 5% by mass, and the strength decreases at 10% by mass.₂O₄The sintered body is broken and sufficient strength is maintained.
[0037]
[2] Solid oxide fuel cell
Example 3 (a fuel cell having a separator having flow paths for fuel gas and supporting gas and having two power generation layers stacked thereon)
(1) Fuel cell structure
FIG. 4 schematically shows a cross section of a flat plate-type SOFC stack 100 in which two power generation layers are stacked.
This flat-plate SOFC stack 100 has a structure in which two power generation layers 2 are stacked via a stacking separator 31. Each of the power generation layers 2 is made of zirconia (ScSZ) stabilized by Sc, and has a solid electrolyte layer 21 having a thickness of 200 μm and a fuel made of Ni and ScSZ and having a thickness of 30 μm. Provided on the top surface of the pole 22 and La_1-xSr_xMnO₃And an air electrode 23 having a thickness of 30 μm. The solid electrolyte layer 21, the fuel electrode 22, and the air electrode 23 are all square in shape, and the solid electrolyte layer 21 has a larger area than the fuel electrode 22 and the air electrode 23, and the fuel electrode 22 and the air electrode 23 are the same size. And it is provided in the position which opposes.
[0038]
The two power generation layers 2 are laminated via a lamination separator 31 made of SUS430. A fuel gas channel 41 is formed on the upper surface of the laminating separator 31, and a combustion-supporting gas channel 42 is formed on the lower surface. Further, an upper separator 32 made of SUS430 is disposed on the upper side of the upper power generation layer 2, and a combustion-supporting gas flow path 42 is formed on the lower surface thereof. Further, a lower separator 33 made of SUS430 is disposed below the lower power generation layer 2, and a fuel gas flow path 41 is formed on the upper surface thereof.
[0039]
Further, the periphery of the solid electrolyte layer 21 of the upper power generation layer 2, the periphery of each of the upper separator 32 and the stacking separator 31, and the periphery of the solid electrolyte layer 21 of the lower power generation layer 2, the lower separator 33 and the stacking layer The peripheral edges of the separators 31 are bonded to form the bonding layer 10. As the bonding material, a bonding material suitable for bonding the solid electrolyte layer and the metal among the specific bonding materials described in [1] (for example, the bonding material of Experimental Example 6) is used. It is firmly joined under the same conditions.
[0040]
(2) Operation of fuel cell
In this solid oxide fuel cell, each solid electrolyte layer of the two power generation layers is made of ScSZ having an ionic conductivity about twice that of YSZ, and is stable even at an operating temperature of about 750 ° C. The electric current can be taken out. Therefore, a separator made of stainless steel such as SUS430 can be used instead of ceramic, and the solid electrolyte layer and the separator contain Ag, Pd, and a small amount of Ti, for example, the specific example of Experimental Example 6 in Example 1 It can be firmly bonded with a bonding material or the like. And it is thought that the compressive stress remains in each joint part, and the tough stack structure which can endure various external forces can be formed.
[0041]
Example 4 (External manifold type fuel cell having two stacked single cells and having a fuel electrode as a substrate)
(1) Fuel cell structure
(1) Power generation layer and various separators
FIG. 5 is a perspective view showing the appearance of a flat plate-type SOFC stack 100 ′ having another structure different from the fuel cell of the third embodiment in which two power generation layers are stacked. 6 is a schematic diagram of the AA cross section in FIG. 5, and FIG. 7 is a schematic diagram of the BB cross section in FIG.
In this flat plate type SOFC stack 100 ′, two single cells are stacked via an intermediate separator 341. The power generation layer provided in each single cell is made of the same material as the fuel cell of Example 3, has a square planar shape, and has a fuel electrode 22 with a thickness of 1000 μm as a substrate. The surface of the fuel electrode 22 is made of the same material as that of the fuel cell of Example 3, and the solid electrolyte layer 21 having the same shape and size in the planar direction as the fuel electrode 22 and a thickness of 30 μm is formed. . Further, the surface of the solid electrolyte layer 21 is made of the same material as that of the fuel cell of Example 3, the shape in the planar direction is the same as that of the solid electrolyte layer 21, the size is smaller than that of the solid electrolyte layer 21, and the thickness is A 30 μm air electrode 23 is formed.
[0042]
The upper unit cell includes a nickel felt layer 5 disposed on the upper surface of the intermediate separator 341, a fuel electrode 22 serving as a substrate, a solid electrolyte layer 21, an air electrode 23, an Inconel fiber mesh layer 6, and a lid member 35 in this order. . Further, the surrounding surface of the Inconel fiber mesh layer 6 is surrounded, the lower surface is joined to the solid electrolyte layer 21, and the upper surface is an insulating ceramic MgO—MgAl.₂O₄It has the isolation | separation separator 36 for upper single cells joined to the cover member 35 via the frame 7 which consists of a sintered compact. On the other hand, the lower unit cell includes a nickel felt layer 5 disposed on the upper surface of the bottom member 37, a fuel electrode 22 serving as a substrate, a solid electrolyte layer 21, an air electrode 23, and an Inconel fiber mesh layer 6 in this order. Further, it has a lower single cell isolation separator 38 which surrounds the peripheral surface of the Inconel fiber mesh layer 6, whose lower surface is bonded to the solid electrolyte layer 21, and whose upper surface is bonded to the intermediate separator 341 via the frame body 7.
[0043]
The lid member 35, the upper unit cell isolation separator 36, the intermediate separator 341, the lower unit cell isolation separator 38, and the bottom member 37 are all made of SUS430. Furthermore, the upper single cell isolation separator 36 and the intermediate separator 341, and the lower single cell isolation separator 38 and the bottom member 37 are joint materials containing Ag, Pd and a small amount of Ti, respectively, particularly for bonding between metals. The bonding layer 10 is formed by bonding with a bonding material having a suitable composition.
[0044]
(2) Fuel gas introduction pipe or exhaust pipe, and combustion-supporting gas introduction pipe or exhaust pipe
In the upper unit cell, a fuel gas introduction pipe 91 for introducing fuel gas into the fuel electrode 22 of the upper unit cell opens in a space formed between the upper unit cell isolation separator 36 and the intermediate separator 341. (See FIG. 6). Further, a fuel gas discharge pipe 92 for discharging the fuel gas from the fuel electrode 22 of the upper single cell is opened at a position diagonal to the opening of the fuel gas introduction pipe 91 in this space (FIG. 7). reference). Furthermore, a through hole 361 for introducing a combustion-supporting gas into the air electrode 23 of the upper unit cell is provided on one side surface of the upper unit cell isolation separator 36 (see FIG. 6). In the diagonal direction on the side surface side, through-holes 362 are provided for discharging the combustion-supporting gas from the air electrode 23 of the upper unit cell (see FIG. 7). These through-holes 361 and 362 communicate with spaces formed between the single separators 36 for the upper unit cell of the lid member 35, and support spaces for introducing a combustion-supporting gas into each space. A flammable gas introduction pipe 93 (see FIG. 6) or a flammable gas discharge pipe 94 (see FIG. 7) for exhaust is opened.
[0045]
On the other hand, in the lower unit cell, a fuel gas introduction pipe 91 for introducing fuel gas into the fuel electrode 22 of the lower unit cell is opened in a space formed between the lower unit cell isolation separator 38 and the bottom member 37. (See FIG. 6). Further, a fuel gas discharge pipe 92 for discharging fuel gas from the fuel electrode 22 of the lower single cell is opened at a position diagonal to the opening of the fuel gas introduction pipe 91 in this space (FIG. 7). reference). Furthermore, a through hole 381 for introducing a combustion-supporting gas into the air electrode 23 of the lower unit cell is provided on one side surface of the lower unit cell isolation separator 38 (see FIG. 6). In the diagonal direction on the side surface side, a through hole 382 for discharging the combustion-supporting gas from the air electrode 23 of the lower single cell is provided (see FIG. 7). These through holes 381 and 382 are communicated with spaces formed between the intermediate separator 341 and the lower single cell isolation separator 38, respectively, and each space is used to introduce a combustion-supporting gas. A combustion-supporting gas introduction pipe 93 (see FIG. 6) or a combustion-supporting gas discharge pipe 94 (see FIG. 7) for discharging is opened.
In the fuel cell of Example 4, when another unit cell is further stacked on the upper surface of the upper unit cell, the lid member functions as an intermediate separator. Further, when another unit cell is further laminated on the lower surface of the lower unit cell, the bottom member functions as an intermediate separator.
[0046]
In addition, each pipe for introducing or discharging fuel gas or combustion-supporting gas into each of the upper unit cell and the lower unit cell has a structure in which a side pipe is attached to the main unit, and the upper power generation layer and Fuel gas or combustion-supporting gas is simultaneously introduced into and discharged from the lower power generation layer. Further, in the case of the fourth embodiment, the fuel gas introduction pipe and the fuel gas discharge pipe, and the fuel support gas introduction pipe and the combustion support gas discharge pipe are respectively circulated in the diagonal direction. It is attached to such a position. Thereby, the fuel electrode and fuel gas of each of the upper power generation layer and the lower power generation layer, and the air electrode and the combustion-supporting gas can be efficiently brought into contact with each other.
[0047]
(2) Extraction of power from the fuel cell
In the flat plate type SOFC stack, the fuel electrode 22 of the upper single cell is electrically connected to the intermediate separator 341 via the nickel felt 5. The intermediate separator 341 is electrically connected to the air electrode 23 of the lower single cell via the Inconel fiber mesh 6. Thus, the upper unit cell and the lower unit cell are connected in series. Further, the stack is heated to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe 91 and brought into contact with the fuel electrode, and a combustion support gas such as air is supplied to the combustion support gas introduction pipe 93. When it is introduced and brought into contact with the air electrode, an electromotive force is generated between the fuel electrode and the air electrode, and this power can be taken out to function as a power generator. Electric power is taken out to the bottom member 37 via the nickel felt 5 disposed on the lower surface of the lower unit cell on the fuel electrode side, and the Inconel fiber mesh 6 disposed on the upper surface of the upper unit cell on the air electrode side. Thus, the lid member 35 can take out the power, and the power of the entire stack can be taken out between the lid member 35 and the bottom member 37.
[0048]
(3) Operation of fuel cell
In this solid oxide fuel cell, each of the two power generation layers is a fuel electrode support type. With this structure, current can be taken out even at an operating temperature of about 750 ° C. Therefore, the lid member, various separators, and the bottom member can be formed of stainless steel such as SUS430 instead of ceramic. In each of the upper unit cell and the lower unit cell, the solid electrolyte layer and the separator are a bonding material suitable for bonding the solid electrolyte layer and the metal among the specific bonding materials described in [1] (for example, The bonding material of Experimental Example 6 is firmly bonded under the same conditions as in Experimental Example 6.
[0049]
Further, the upper single cell isolation separator 36, one surface of the frame 7 made of insulating ceramic, the other surface of the frame 7 and the lid member 35, the lower single cell isolation separator 38, and the frame made of insulating ceramic. 7 and the other surface of the frame 7 and the intermediate separator 341 are bonding materials suitable for bonding the insulating ceramic and the metal among the specific bonding materials described in [1] (for example, in Experimental Example 16). The bonding material) is firmly bonded under the same conditions as in Experimental Example 16. Further, the upper single cell isolation separator 36 and the intermediate separator 341, and the lower single cell isolation separator 38 and the bottom member 37 have the same composition as the specific bonding material described in [1] above, and are bonded between metals. It is firmly bonded with a bonding material suitable for the above. In this way, each joint is joined by a joining material containing Ag, Pd and a small amount of Ti, and it is considered that compressive stress remains in each joint, and various external forces are applied. It is possible to form a tough stack structure that can withstand.
[0050]
Example 5 (Internal manifold type fuel cell having three unit cells stacked and having a fuel electrode as a substrate)
(1) Fuel cell structure
(1) Power generation layer and various separators
FIG. 8 is a perspective view showing the external appearance of a flat plate-type SOFC stack 100 ″ having another structure different from the fuel cells of Examples 3 and 4 in which three power generation layers are stacked. FIG. 10 is a schematic diagram of the AA cross section in FIG. 8, and FIG. 10 is a schematic diagram of the BB cross section in FIG.
In this flat plate type SOFC stack 100 ″, three single cells are stacked via intermediate separators 342 and 343. The power generation layer provided in each single cell is made of the same material as the fuel cell of Example 3. The fuel electrode 22 having a square shape and a thickness of 1000 μm is used as the substrate, and the surface of the fuel electrode 22 is made of the same material as that of the fuel cell of Example 3, and the shape and dimensions in the planar direction are the fuel. A solid electrolyte layer 21 having the same thickness as that of the electrode 22 and having a thickness of 30 μm is formed on the surface of the solid electrolyte layer 21. The solid electrolyte layer 21 is made of the same material as that of the fuel cell of Example 3 and has a planar shape. Is the same as the solid electrolyte layer 21, and the air electrode 23 having a size smaller than that of the solid electrolyte layer 21 and a thickness of 30 μm is formed.
[0051]
The upper unit cell includes a nickel felt layer 5 disposed on the upper surface of the intermediate separator 342, a fuel electrode 22 serving as a substrate, a solid electrolyte layer 21, an air electrode 23, an Inconel fiber mesh layer 6, and a lid member 35 in this order. . The lower surface is joined to the solid electrolyte layer 21 and the metal frame 82, and the upper surface is MgO-MgAl which is an insulating ceramic.₂O₄The upper single cell isolation separator 36 is joined to the lid member 35 via the frame 7 made of a sintered body and the metal frame 81.
The intermediate single cell includes the nickel felt layer 5 disposed on the upper surface of the intermediate separator 343, the fuel electrode 22 serving as a substrate, the solid electrolyte layer 21, the air electrode 23, and the Inconel fiber mesh layer 6 in this order. The lower surface is joined to the solid electrolyte layer 21 and the metal frame 84, and the upper surface is an insulating ceramic MgO—MgAl.₂O₄An intermediate single-cell isolation separator 39 joined to the intermediate separator 342 through a frame 7 made of a sintered body and a metal frame 83 is provided.
The lower unit cell includes a nickel felt layer 5 disposed on the upper surface of the bottom member 37, a fuel electrode 22 serving as a substrate, a solid electrolyte layer 21, an air electrode 23, and an Inconel fiber mesh layer 6 in this order. Further, the lower single cell isolation separator 38 has a lower surface joined to the solid electrolyte layer 21 and the metal frame 86 and an upper surface joined to the intermediate separator 343 via the frame 7 and the metal frame 85.
[0052]
Lid member 35, upper single cell isolation separator 36, lower single cell isolation separator 38, intermediate single cell isolation separator 39, intermediate separators 342 and 343, metal frame bodies 81, 82, 83, 84, 85, 86 and The bottom members 37 are all formed of SUS430. Further, the lid member 35 and the metal frame 81, the upper single cell isolation separator 36 and the metal frame 82, the metal frame 82 and the intermediate separator 342, the intermediate separator 342 and the metal frame 83, for the intermediate single cell Isolation separator 39 and metal frame 84, metal frame 84 and intermediate separator 343, intermediate separator 343 and metal frame 85, lower single cell isolation separator 38 and metal frame 86, and metal frame 86 And the bottom member 37 are bonded to each other by a bonding material having a composition suitable for bonding between metals among bonding materials containing Ag, Pd, and a small amount of Ti, respectively, and the bonding layer 10 is formed.
[0053]
(2) Fuel gas introduction pipe or exhaust pipe, and combustion-supporting gas introduction pipe or exhaust pipe
In the upper unit cell, a fuel gas introduction pipe 91 for introducing fuel gas into the fuel electrode 22 of the upper unit cell opens in a space formed between the upper unit cell isolation separator 36 and the intermediate separator 342. (See FIG. 9). Further, a fuel gas discharge pipe 92 for discharging fuel gas from the fuel electrode 22 of the upper single cell is opened on the side of the space facing the opening of the fuel gas introduction pipe 91 (see FIG. 9). . Further, in the space formed between the lid member 35 and the upper unit cell isolation separator 36, a support gas introducing pipe 93 for introducing the support gas into the air electrode 23 of the upper unit cell is opened. (See FIG. 10). In addition, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 23 of the upper unit cell is opened on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. (See FIG. 10).
[0054]
Further, in the intermediate unit single cell, a fuel gas introduction for introducing the fuel gas into the fuel electrode 22 of the intermediate unit single cell is formed in the space formed between the intermediate unit single cell isolation separator 39 and the intermediate separator 343. The tube 91 is open (see FIG. 9). Further, a fuel gas discharge pipe 92 for discharging fuel gas from the fuel electrode 22 of the upper single cell is opened on the side of the space facing the opening of the fuel gas introduction pipe 91 (see FIG. 9). . Further, in a space formed between the intermediate separator 342 and the intermediate unit cell isolation separator 39, a combustion supporting gas introduction pipe 93 for introducing the combustion supporting gas into the air electrode 23 of the intermediate unit cell. Is open (see FIG. 10). Further, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 23 of the upper unit cell opens on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. (See FIG. 10).
[0055]
Further, in the lower unit cell, in a space formed between the lower unit cell isolation separator 38 and the bottom member 37, a fuel gas introduction pipe 91 for introducing fuel gas into the fuel electrode 22 of the lower unit cell is provided. Open (see FIG. 9). A fuel gas discharge pipe 92 for discharging fuel gas from the fuel electrode 22 of the lower single cell is opened on the side of the space facing the opening of the fuel gas introduction pipe 91 (see FIG. 9). . Further, in the space formed between the intermediate separator 343 and the lower single cell isolation separator 38, a support gas introduction pipe 93 for introducing the support gas into the air electrode 23 of the lower unit cell is opened. (See FIG. 10). In addition, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 23 of the lower single cell is opened on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. (See FIG. 10).
In the fuel cell of Example 5, when another unit cell is further stacked on the upper surface of the upper unit cell, the lid member functions as an intermediate separator. Furthermore, when another unit cell is laminated on the lower surface of the lower unit cell, the bottom member functions as an intermediate separator.
[0056]
In addition, each pipe for introducing or discharging fuel gas or combustion-supporting gas into each of the upper unit cell, middle unit cell and lower unit cell has a structure in which a side tube is attached to the main tube. The fuel gas or the combustion-supporting gas is simultaneously introduced into and discharged from the upper power generation layer, the middle power generation layer, and the lower power generation layer. Further, in the case of the fifth embodiment, the fuel gas introduction pipe and the fuel gas discharge pipe, and the fuel support gas introduction pipe and the fuel support gas discharge pipe are respectively circulated in the opposing direction. It is attached to such a position. Thereby, each fuel electrode of each of the upper power generation layer, the middle power generation layer, and the lower power generation layer can be efficiently brought into contact with the fuel gas, and the air electrode and the combustion-supporting gas.
[0057]
(2) Extraction of power from the fuel cell
In the flat plate type SOFC stack, the fuel electrode 22 of the upper single cell is electrically connected to the intermediate separator 342 through the nickel felt 5. Further, the intermediate separator 342 is electrically connected to the air electrode 23 of the intermediate unit single cell via the Inconel fiber mesh 6. Further, the fuel electrode 22 of the intermediate unit single cell is electrically connected to the intermediate separator 343 via the nickel felt 5. Further, the intermediate separator 343 is electrically connected to the air electrode 23 of the lower single cell via the Inconel fiber mesh 6. In this way, the upper unit cell, the middle unit cell, and the lower unit cell are each connected in series. Further, the stack is heated to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe 91 and brought into contact with the fuel electrode 22, and a combustion-supporting gas such as air is introduced into the combustion-supporting gas introduction pipe 93. Is introduced and brought into contact with the air electrode 23, an electromotive force is generated between the fuel electrode 22 and the air electrode 23, and the power can be taken out to function as a power generator. Electric power is taken out to the bottom member 37 via the nickel felt 5 disposed on the lower surface of the lower unit cell on the fuel electrode side, and the Inconel fiber mesh 6 disposed on the upper surface of the upper unit cell on the air electrode side. Thus, the lid member 35 can take out the power, and the power of the entire stack can be taken out between the lid member 35 and the bottom member 37.
[0058]
(3) Operation of fuel cell
In this solid oxide fuel cell, each of the three power generation layers is a fuel electrode support type. With this structure, current can be taken out even at an operating temperature of about 750 ° C. Therefore, the lid member, various separators, the metal frame, and the bottom member can be formed of stainless steel such as SUS430 instead of ceramic. In each of the upper unit cell, the middle unit cell, and the lower unit cell, the solid electrolyte layer and the separator are suitable for bonding the solid electrolyte layer and the metal among the specific bonding materials described in [1] above. The bonding material (for example, the bonding material of Experimental Example 6) is firmly bonded under the same conditions as in Experimental Example 6.
[0059]
Further, the upper single cell isolation separator 36, one surface of the frame 7 made of insulating ceramic, the other surface of the frame 7 and the metal frame 81, the intermediate single cell isolation separator 39, and the insulating ceramic are used. One surface of the frame 7 and the other surface of the frame 7 and the metal frame 83, and the lower single cell isolation separator 38, one surface of the frame 7 made of insulating ceramic, and the other surface of the frame 7 and the metal frame The body 85 is a joint material (for example, the joint material of Experimental Example 14) suitable for joining an insulating ceramic and a metal among the specific joint materials described in [1] above, under the same conditions as in Experimental Example 14. It is firmly joined. Also, the lid member 35 and the metal frame 81, the upper single cell separator 36 and the metal frame 82, the metal frame 82 and the intermediate separator 342, the intermediate separator 342 and the metal frame 83, the intermediate unit cell Isolation separator 39 and metal frame 84, metal frame 84 and intermediate separator 343, intermediate separator 343 and metal frame 85, lower single cell isolation separator 39 and metal frame 86, and metal frame 86 and the bottom member 37 have the same composition as the specific bonding material described in [1] above, and are firmly bonded by a bonding material suitable for bonding between metals.
In this way, each joint is joined by a joining material containing Ag, Pd and a small amount of Ti, and it is considered that compressive stress remains in each joint, and various external forces are applied. It is possible to form a tough stack structure that can withstand.
[0060]
[3] Fuel gas and supporting gas
When power is generated using the solid oxide fuel cells of Example 3, Example 4, and Example 5, fuel gas is introduced to the fuel electrode side, and combustion-supporting gas is introduced to the air electrode side. As fuel gas, hydrogen, hydrocarbon as a hydrogen source, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and fuel obtained by mixing these gases with water vapor Gas etc. are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. Further, the main components are saturated hydrocarbons having 1 to 10, preferably 1 to 7, more preferably 1 to 4 carbon atoms such as methane, ethane, propane, butane and pentane, and unsaturated hydrocarbons such as ethylene and propylene. Those having a saturated hydrocarbon as a main component are more preferable. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.
[0061]
Examples of the combustion-supporting gas include a mixed gas of oxygen and another gas. The mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Among these combustion-supporting gases, air (containing about 80% by volume of nitrogen) is preferable because it is safe and inexpensive.
[0062]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention depending on the purpose, application, and the like. For example, the planar shape of the power generation layer or the like can be a rectangle, a circle, an ellipse, or the like, and a solid oxide fuel cell having a similar planar shape can be obtained. Further, in the flat plate type SOFC stack, metal molded bodies such as various separators can be joined by a method such as welding. However, for example, the inside of the through hole at the periphery of the separator in the internal manifold type stack shown as a conventional fuel cell in FIG. 11 cannot be joined by welding. In this case, if the specific bonding material in [1] is used, the periphery of the through hole can be sufficiently airtightly sealed with Ag having excellent spreadability.
[0063]
Furthermore, the material used for forming the solid electrolyte layer is not limited to ScSZ, and can be appropriately selected depending on the use conditions of the SOFC. As this material, for example, ZrO₂Ceramic, LaGaO₃Ceramic, BaCeO₃Ceramic, SrCeO₃Ceramic, SrZrO₃Ceramics and CaZrO₃And ceramics. Among these ceramic materials, ZrO₂Based ceramics, ZrO stabilized by at least one of Y and rare earth elements₂Based ceramics are preferred. These stabilized zirconia also has excellent ionic conductivity and mechanical strength similar to ScSZ.
The thickness of the solid electrolyte layer can be set to 5 to 100 μm, particularly 5 to 50 μm, and further 5 to 30 μm in consideration of electric resistance and strength.
[0064]
Further, the material used for forming the fuel electrode is not limited to Ni and ScSZ, and can be appropriately selected depending on the use conditions of the SOFC. Examples of this material include metals such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe. These metals may be used alone or in an alloy of two or more metals. In addition, a mixture (including cermet) of these metals and / or alloys and zirconia ceramics such as zirconia stabilized by at least one of Y and rare earth elements, ceria ceramics, and ceramics such as manganese oxide. ). Furthermore, the mixture etc. of the oxide of metals, such as Ni and Fe, and at least 1 sort (s) of the said ceramic are mentioned.
The planar shape of the fuel electrode is not particularly limited, but is preferably the same shape as the solid electrolyte layer and the air electrode. Furthermore, the fuel electrode and the solid electrolyte layer are preferably laminated on the entire surface.
[0065]
In the solid oxide fuel cell, it is not preferable that the power generation layer of each single cell is excessively thin from the viewpoint of strength, but it is not preferable to increase the thickness of the solid electrolyte layer as described above from the viewpoint of power generation performance. . Therefore, it can be a fuel electrode support type as in Example 4 and Example 5, and in this fuel electrode support type, the fuel electrode is preferably 20 times or more thicker than the solid electrolyte layer. If it is less than 20 times, the mechanical strength of the power generation layer tends to be insufficient. The thickness of the fuel electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, an air electrode support type can also be used. In this case, the thickness of the fuel electrode is preferably 10 to 50 μm, particularly preferably 20 to 40 μm. If this thickness is 10 to 50 μm, it functions sufficiently as an electrode and does not need to be thicker than 50 μm.
[0066]
The material used to form the air electrode is La_1-xSr_xMnO₃It is not limited to the system complex oxide, and can be appropriately selected depending on the use conditions of SOFC. Examples of this material include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh. These metals may be used alone or in an alloy of two or more metals. In addition, oxides such as La, Sr, Ce, Co, and Mn (for example, La₂O₃, SrO, Ce₂O₃, Co₂O₃, MnO₂And FeO). Furthermore, various composite oxides containing at least one of La, Sr, Ce, Co, Mn, etc. (for example, La_1-xSr_xCoO₃-Based complex oxide, La_1-xSr_xFeO₃-Based complex oxide, La_1-xSr_xCo_1-yFe_yO₃-Based complex oxide, Pr_1-xBa_xCoO₃-Based composite oxide and Sm_1-xSr_xCoO₃Based composite oxides).
[0067]
Of these materials, composite oxides are preferred, and moreover Ln_1-xM_xCoO₃CeO-based composite oxide (where Ln is a rare earth element and M is Sr or Ba)₂It is preferably used in combination with a reaction preventing layer made of a system oxide. This Ln_1-xM_xCoO₃In the composite oxide, Ln and M may be further substituted with another element. These Ln_1-xM_xCoO₃Among the composite oxides, the composition formula Ln_1-xM_xCoO_{Three ± δ}It is particularly preferable that 0.2 ≦ x ≦ 0.8 and 0 ≦ δ <1 (δ represents oxygen excess or oxygen deficiency), and Ln is La, Pr and Sm. What is at least 1 type of them is still more preferable. Such Ln_1-xM_xCoO₃Examples of the composite oxide include La_0.6Sr_0.4CoO_{Three ± δ}, Pr_0.5Ba_0.5CoO_{Three ± δ}And Sm_0.5Sr_0.5CoO_{Three ± δ}Etc.
[0068]
Furthermore, the planar shape of the air electrode is not particularly limited, but is preferably the same shape as the solid electrolyte layer and the fuel electrode. Furthermore, the dimension in the planar direction may be the same as that of the solid electrolyte layer and the fuel electrode depending on the structure of the fuel cell. When the separator is joined to the peripheral edge of one surface of the solid electrolyte layer, the air electrode is formed smaller than the solid electrolyte layer and the fuel electrode. The air electrode and the solid electrolyte layer are preferably laminated on the entire surface.
[0069]
As described above, the air electrode may be formed as a substrate that supports the strength of the power generation layer. In the case of the air electrode support type, the thickness of the air electrode is preferably 20 times or more that of the solid electrolyte layer. If it is less than 20 times, the mechanical strength of the power generation layer tends to be insufficient. The thickness of the air electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, in the case of the fuel electrode support type, the thickness of the air electrode is preferably 10 to 100 μm, particularly preferably 20 to 50 μm. When the thickness is less than 10 μm, the electrode may not function sufficiently, and when the thickness exceeds 100 μm, the solid electrolyte layer may be peeled off.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a cross section of a laminate according to the present invention.
FIG. 2 is an explanatory view schematically showing an example of a plurality of layers constituting a joint portion.
FIG. 3 is a graph showing the relationship between the amount of Ti contained in a bonding material and bonding strength.
FIG. 4 is a schematic view showing a cross section of an example (Example 3) of the fuel cell of the present invention.
FIG. 5 is a perspective view showing the appearance of another example (Example 4) of the fuel cell of the present invention.
6 is a schematic view showing an AA cross section of the fuel cell of FIG. 5. FIG.
7 is a schematic diagram showing a BB cross section of the fuel cell of FIG. 5. FIG.
FIG. 8 is a perspective view showing the appearance of still another example (Example 5) of the fuel cell according to the present invention.
9 is a schematic diagram showing a cross section of the fuel cell of FIG. 8 taken along the line AA.
10 is a schematic view showing a BB cross section of the fuel cell of FIG. 8. FIG.
FIG. 11 is an exploded perspective view schematically showing an example of a conventional internal manifold type fuel cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Laminated body, 11; Ceramic molded body, 12; Stainless steel molded body, 13; Joining part, 131, 132; Ti segregation layer, 133; Reaction layer of Ti, Ag, and Pd, containing a predetermined amount of Ti Layer 134 containing Ti, Ag and Pd and containing a large amount of Ag 135, a reaction layer of Ti, Ag and Pd, a layer containing less Ti than the layer 133, 136; Ag Layer containing Pd, 100, 100 ′; flat plate SOFC stack, 21; solid electrolyte layer, 22; fuel electrode, 23; air electrode, 31; separator for lamination, 32; upper separator, 33; 342, 343; intermediate separator 35; lid member 36; upper single cell isolation separator 361, 362; through hole 37; bottom member 38; lower single cell isolation separator 381, 3 2; Through-hole, 39; Separation separator for intermediate single cell, 41; Fuel gas flow path, 42; Combustion gas flow path, 5; Nickel felt layer, 6; Inconel fiber mesh layer, 7; 81, 82, 83, 84, 85, 86; metal frame, 91; fuel gas introduction pipe, 92; fuel gas exhaust pipe, 93; combustion-supporting gas introduction pipe, 94; A bonding layer.

Claims (12)

A laminated body in which a ceramic molded body and a heat-resistant alloy molded body are bonded together by a bonding material, wherein the bonding material contains Ag and Pd. The said bonding | jointing material contains Ti further, When the sum total of said Ag, said Pd, and this Ti is 100 mass%, content of this Ti is 0.05-10 mass%. Laminated body. The laminate according to claim 1 or 2, wherein the bonding temperature is not lower than a solid phase point temperature of the bonding material and not higher than a temperature exceeding the liquid phase point temperature by 50 ° C. The laminated body according to any one of claims 1 to 3, wherein the ceramic molded body is a molded body made of stabilized zirconia. The laminate according to any one of claims 1 to ₄ , wherein the ceramic molded body is a molded body made of a ceramic containing MgO and MgAl ₂ O ₄ . A solid oxide fuel cell comprising a structure formed by the laminate according to any one of claims 1 to 5. In a solid oxide fuel cell having a structure in which a plurality of power generation layers are laminated via isolation separators made of a heat-resistant alloy, each power generation layer includes a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, And an air electrode provided on the other surface, the separator is partially joined to each solid electrolyte layer of the adjacent power generation layer, and for introducing the fuel gas into the fuel electrode of one power generation layer A flow path and a flow path for introducing a combustion-supporting gas into the air electrode of the other power generation layer, and each solid electrolyte layer and the separator separator are bonded by a bonding material containing Ag and Pd. A solid oxide fuel cell. In a solid oxide fuel cell having a structure in which a plurality of single cells are stacked via an intermediate separator, each single cell is provided on a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, and on the other surface. A power generation layer having an air electrode provided, a part of which is joined to the solid electrolyte layer, and a flow path for introducing a fuel gas into the fuel electrode, and a combustion-supporting gas into the air electrode A separator made of a heat-resistant alloy that separates the flow path, and a frame made of an insulating ceramic is disposed between at least a part of the intermediate separator and the separator, and at least each of the solid electrolyte layers, The isolation separator is joined by a joining material containing Ag and Pd, respectively, and is a solid oxide fuel cell. 9. The solid oxide fuel cell according to claim 8, wherein at least a part of the intermediate separator and the separator and the frame body are joined by a joining material containing Ag and Pd, respectively. The solid oxide fuel cell according to claim 8 or 9, wherein the insulating ceramic contains MgO and MgAl ₂ O ₄ . The content of Ti is 0.05 to 10% by mass when the bonding material further contains Ti and the total of Ag, Pd and Ti is 100% by mass. The solid oxide fuel cell of any one of them. The solid oxide fuel cell according to any one of claims 7 to 11, wherein a temperature of the bonding is not lower than a solid phase temperature of the bonding material and not higher than a temperature exceeding a liquid phase temperature of 50 ° C. .

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