JP3667297B2

JP3667297B2 - Solid oxide fuel cell and method for producing the same

Info

Publication number: JP3667297B2
Application number: JP2002151670A
Authority: JP
Inventors: 雅英秋山; 祥二山下; 良雄松崎
Original assignee: Kyocera Corp; Tokyo Gas Co Ltd
Current assignee: Kyocera Corp; Tokyo Gas Co Ltd
Priority date: 2002-05-27
Filing date: 2002-05-27
Publication date: 2005-07-06
Anticipated expiration: 2016-06-27
Also published as: JP2003017073A

Description

【０００１】
【発明の属する技術分野】
本発明は、固体電解質型燃料電池セルおよびその製造方法に関するもので、特に燃料極の改良に関するものである。
【０００２】
【従来技術】
従来より、固体電解質型燃料電池はその作動温度が１０００〜１０５０℃と高温であるため発電効率が高く、第３世代の発電システムとして期待されている。
【０００３】
一般に、固体電解質型燃料電池セルには円筒型と平板型が知られている。平板型燃料電池セルは、発電の単位体積当り出力密度が高いという特長を有するが、実用化に関してはガスシール不完全性やセル内の温度分布の不均一性などの問題がある。それに対して、円筒型燃料電池セルでは、出力密度は低いものの、セルの機械的強度が高く、またセル内の温度の均一性が保てるという特長がある。両形状の固体電解質型燃料電池セルとも、それぞれの特長を生かして積極的に研究開発が進められている。
【０００４】
円筒型燃料電池の単セルは、図１に示したように開気孔率４０％程度のＣａＯ安定化ＺｒＯ₂を支持管１とし、その上にＬａＭｎＯ₃系材料からなる多孔性の空気極２を形成し、その表面にＹ₂Ｏ₃安定化ＺｒＯ₂からなる固体電解質３を被覆し、さらにこの表面に多孔性のＮｉ−ジルコニアの燃料極４が設けられている。燃料電池のモジュ−ルにおいては、各単セルはＣａ、Ｓｒ、Ｍｇを固溶させたＬａＣｒＯ₃系材料からなるインタ−コネクタ５を介してＮｉフェルトで接続される。このような燃料電池の発電は、各単セルを１０００℃程度の温度で保持するとともに、支持管１内部に空気（酸素）６を、外部に燃料ガス７、例えば、水素、都市ガス等を供給することにより行われる。
【０００５】
そして、近年、セル作製工程においてプロセス単純化のため、空気極材料であるＬａＭｎＯ₃系材料を直接多孔性の支持管として使用する試みがなされている。空気極としての機能を併せ持つ支持管材料としては、ＬａをＣａあるいはＳｒで１０〜２０原子％置換したＬａＭｎＯ₃固溶体材料が用いられている。
【０００６】
また、平板型燃料電池の単セルは、円筒型セルと同じ材料系を用いて図２に示したように固体電解質８の一方に多孔性の空気極９が、他方に多孔性の燃料極１０が設けられている。単セル間の接続は、セパレータ１１と呼ばれるＭｇやＣａを添加した緻密質のＬａＣｒＯ₃材料が用いられる。
【０００７】
そして、上記した円筒型および平板型の固体電解質型燃料電池セルの燃料極は、一般的にＮｉ粉末とＺｒＯ₂（Ｙ₂Ｏ₃含有）粉末あるいはＮｉＯ粉末とＺｒＯ₂（Ｙ₂Ｏ₃含有）粉末の混合粉末をスクリーン印刷法により固体電解質表面に塗布するか、あるいは混合粉末を含有する溶液中に浸漬した後、乾燥し燃料極として形成されていた。また、後者のＮｉＯ／ＺｒＯ₂（Ｙ₂Ｏ₃含有）混合粉末の場合は、１０００〜１４００℃の還元雰囲気で熱処理して燃料極として形成されていた。
【０００８】
【発明が解決しようとする課題】
しかしながら、これらの方法で作製された燃料極は長時間の発電においてＮｉ（ＮｉＯは発電中に還元されＮｉとなる）の凝集や粒成長により発電性能が低下するという大きな問題が発生していた。
【０００９】
また、近年、この問題を解決するため、特開平７−２２０３２号に開示されるように、ＺｒおよびＹ元素を含むオクチル酸塩、ナフテン酸塩等の有機金属化合物を熱分解させ、Ｎｉ等の金属粒子表面に微粒のＺｒＯ₂（Ｙ₂Ｏ₃含有）セラミック粒子を析出させてＮｉの凝集や焼結による性能低下を抑制する方法が提案されているが、この方法においてもＮｉの凝集や焼結を防止するには充分ではなかった。
【００１０】
【課題を解決するための手段】
本発明は、上記問題に検討を加えた結果、セラミック粒子により骨格を形成し、その骨格の空孔中に、表面と内部に微粒のセラミック粒子を析出させた金属粒子を分散させることにより、さらに金属の凝集や焼結の抑制効果を向上でき、燃料極の固体電解質への付着強度も向上できることを見出し本発明に至った。
【００１１】
即ち、本発明の固体電解質型燃料電池セルは、固体電解質の片面に多孔性の空気極、他面に多孔性の燃料極が形成された固体電解質型燃料電池セルにおいて、前記燃料極がセラミック粒子を骨格とする多孔質体の空孔内に、表面と内部に微粒のセラミック粒子が析出した金属粒子を分散してなるものである。
【００１２】
また、本発明の固体電解質型燃料電池セルの製造方法は、固体電解質の片面に多孔性の空気極、他面に多孔性の燃料極が形成された固体電解質型燃料電池セルの製造方法であって、前記燃料極を、Ｎｉ、Ｃｏ、ＦｅおよびＲｕのうち少なくとも１種以上の金属元素と、Ｚｒおよび／またはＣｅと、を含む有機金属化合物溶液を、セラミック粒子を骨格とする多孔質体の空孔内に注入して熱分解させ、該多孔質体の空孔内に、表面および内部に微粒のセラミック粒子が析出した金属粒子を分散せしめる方法である。
【００１４】
【作用】
本発明の固体電解質型燃料電池セルでは、セラミック粒子により形成された骨格（多孔質体）の空孔内に、表面と内部に微粒のセラミック粒子を析出させた金属粒子を分散させることにより、金属の凝集や粒成長が抑制されるとともに、燃料極の固体電解質への付着強度が向上し、その結果出力密度が向上し、さらに、熱サイクルに対しても安定した出力が得られる。
【００１５】
【発明の実施の形態】
本発明の固体電解質型燃料電池セルにおける燃料極の基本構造は、図４に示すように、固体電解質３表面に粗粒のセラミック粒子３５で構成した多孔質体（骨格）３６の空孔中に、表面と内部に膜状および／または粒子状に微粒のセラミック粒子３７が析出した金属３９を分散させた構造を有する。
【００１６】
この様な燃料極４においては、粗粒のセラミック粒子３５が骨格を形成しているため、燃料極４の固体電解質３への付着強度が高く、温度サイクルによる燃料極４の剥離が極めて少なくなり高い出力密度を有する。骨格を形成するセラミック粒子３５および微粒のセラミック粒子３７とも、ＺｒＯ₂、ＣｅＯ₂単体、またはこれらの固溶体、あるいはＹ、Ｙｂ、Ｓｃ、Ｓｍ、Ｎｄ、Ｄｙ、Ｐｒ等の希土類元素酸化物を含有するＺｒＯ₂、ＣｅＯ₂から構成されることが好ましい。
【００１７】
この場合、金属が５０〜９５重量％（金属換算）、微粒のセラミック粒子が１〜２０重量％、粗粒のセラミック粒子が４〜３０重量％の範囲が優れる。金属が９５重量％より多い場合、または微粒のセラミック粒子が１重量％より少ない場合、または粗粒のセラミック粒子が４重量％より少ない場合には、発電時の金属の凝集、粒成長の抑制効果が小さい。また、金属が５０重量％より少ない場合、または微粒のセラミック粒子が２０重量％より多い場合、あるいは粗粒のセラミック粒子が３０重量％より多い場合には、電気伝導性が低下して発電性能が悪くなる傾向にある。特に、金属が６０〜８０重量％（金属換算）、微粒のセラミック粒子が１０〜２０重量％、粗粒のセラミック粒子が１０〜２０重量％の範囲が優れる。
【００１８】
骨格を形成する粗粒のセラミック粒子の大きさとしては、平均粒子径で０．５〜３０μｍ、特に２〜１０μｍの範囲が優れる。また、微粒のセラミック粒子の一次粒子の大きさとしては、平均粒子径で０．０１〜０．５μｍ、特に０．１〜０．５μｍの範囲が優れる。
【００１９】
このような燃料極中のセラミックの骨格は、まず粗粒のセラミック粒子を固体電解質表面にスクリーン印刷あるいはスラリーディップ等の周知の技術により塗布した後、酸化性雰囲気中で１０００〜１７００℃、好ましくは１２００〜１４００℃の温度で１〜１０時間熱処理して形成する。その後、Ｎｉ、Ｃｏ、Ｆｅ、Ｒｕの金属元素と、Ｚｒおよび／またはＣｅと、を同時に含む有機金属化合物溶液、例えば、オクチル酸塩、ナフテン酸塩、ネオデカン酸塩、エチルヘキサン酸塩、プロピオン酸塩をトルエン等の溶剤に溶解させた溶液を骨格中に含浸した後、酸化性雰囲気中で４００〜１６００℃の温度で熱分解させ、金属表面および内部に微粒のセラミックを析出させて燃料極が形成される。尚、熱分解後は金属酸化物の表面および内部に微粒のセラミック粒子が析出した状態であるが、後の還元処理により、金属酸化物は金属粒子となる。
【００２２】
尚、燃料極中の金属成分としては、上述のＮｉ、Ｃｏ等の酸化物の他に、熱処理により酸化物を形成する炭酸塩、酢酸塩、臭酸塩等も使用することができる。
【００２３】
また、上記方法において、有機金属化合物溶液には、Ｚｒおよび／またはＣｅの他に、Ｙおよび希土類元素から選ばれる元素を含有しても良い。
【００２４】
固体電解質型燃料電池セルにおける燃料極として、図３に示すように、例えば固体電解質３表面の燃料極４がＮｉ等の金属粒子３１の表面に微粒のセラミック粒子３３が膜状および／あるいは微粒子の状態で析出し、さらに内部に微粒のセラミック粒子３３が析出している。この微粒なセラミック粒子３３の一次粒子径は熱処理条件等の作成条件により変化するが、平均粒子径としては０．０１〜０．５μｍ程度の大きさからなる。金属粒子の平均粒径は、１〜２０μｍ、電気伝導性およびガス透過性の観点から５〜１０μｍであることが望ましい。
【００２５】
図３の燃料極４では、金属粒子３１としては、Ｎｉの他Ｃｏ、Ｆｅ、Ｒｕの単体およびそれらの合金が使用される。また、微粒のセラミック粒子３３としてはＺｒＯ₂、ＣｅＯ₂の単体、およびそれらの固溶体の他、Ｙ、Ｙｂ、Ｓｃ、Ｓｍ、Ｎｄ、Ｄｙ、Ｐｒ等の希土類元素を１〜３０モル％含有するＺｒＯ₂固溶体またはＣｅＯ₂固溶体、およびＹや希土類元素を含有したＺｒＯ₂とＣｅＯ₂の固溶体を用いることができる。これらの中で経済性の観点から燃料極材料としてはＮｉとＺｒＯ₃（Ｙ₂Ｏ₃含有）あるいはＮｉとＣｅＯ₂の組み合わせが好ましい。
【００２６】
このような燃料極構造は、Ｎｉ、Ｃｏ、Ｆｅ、Ｒｕの金属元素と、Ｚｒおよび／またはＣｅと、を同時に含む有機金属化合物溶液、例えば、オクチル酸塩、ナフテン酸塩、ネオデカン酸塩、エチルヘキサン酸塩、プロピオン酸塩等をトルエン等の溶剤に溶解させた溶液を固体電解質表面にスクリーン印刷あるいはスラリーディップ等の周知の技術により塗布した後、酸化性雰囲気中で４００〜１６００℃の温度で１〜１０時間熱分解させて作製される。有機金属化合物溶液には、Ｙおよび希土類元素から選ばれる元素を含んでも良い。酸化雰囲気中での熱処理においては、Ｎｉ、Ｃｏ、Ｆｅ金属は酸化されるため、還元雰囲気中での再処理が必要である。金属酸化物を還元するためには、酸素濃度が１％以下のＮ₂、Ａｒ中で熱処理することが望ましい。
【００２７】
Ｎｉ等の金属粒子３１の表面および内部に微粒のセラミック粒子３３を析出させるには、Ｎｉ等の金属粒子と、Ｚｒおよび／またはＣｅと、を同時に含む有機金属化合物溶液を用いる必要がある。
【００２８】
図３に示す燃料極においては、Ｎｉ、Ｃｏ、Ｆｅ、Ｒｕ金属とＹおよび希土類元素から構成される酸化物との重量比率は、Ｎｉ、Ｃｏ、Ｆｅ，Ｒｕが金属換算で９９〜５０重量％、Ｚｒおよび／またはＣｅの酸化物（Ｙおよび希土類元素を含有する場合も含む）が１〜５０重量％の範囲が好ましい。Ｎｉ等の金属が９９重量％より多いと、金属の発電時の凝集あるいは粒成長を充分抑制できない。それに対して、Ｎｉ等の金属が５０重量％より少なくなると、電気伝導性が低下して発電性能が悪くなる傾向にあるからである。これら金属と酸化物との重量比率としては、金属が８０〜９０重量％、Ｚｒおよび／またはＣｅの酸化物（Ｙおよび希土類元素を含有する場合も含む）が１０〜２０重量％が特に好ましい。
【００２９】
また、燃料極の厚みとしては電気伝導性とガスの透過率の観点から、平板型セルの場合２０〜２００μｍが、円筒型セルの場合は３０〜３００μｍの範囲が優れる。
【００３０】
本発明により構成される円筒型燃料電池セルの構造は、例えば、図１に示したように開気孔率４０％程度のＹ₂Ｏ₃あるいはＣａＯ安定化ＺｒＯ₂を支持管１とし、その上にスラリーディップ法により多孔性の空気極２としてＬａをＣａ、Ｓｒで１０〜２０原子％置換したＬａＭｎＯ₂系材料を塗布し、その表面に気相合成法（ＥＶＤ）や、あるいは溶射法により固体電解質３であるＹ₂Ｏ₃安定化ＺｒＯ₂膜あるいはＹ₂Ｏ₃，Ｙｂ₂Ｏ₃あるいはＣａＯ含有するＣｅＯ₂膜を被覆し、さらにこの表面に多孔性の本発明の図４の燃料極４が形成されている。また、本発明の燃料電池セルは、支持管を用いることなく、ＬａをＣａ、Ｓｒで１０〜２０原子％置換したＬａＭｎＯ₃からなる空気極を支持管として用いても良い。
【００３１】
また、インターコネクタ５と呼ばれる集電体としては、５〜２０モル％のＣａＯ、ＭｇＯを添加したＬａＣｒＯ₃が気相合成法や溶射法を用いて空気極と接するように形成される。
【００３２】
また、平板型セルにおいても、円筒型セルと同一の材料を用いて、図２のように作製することができる。
【００３３】
尚、本発明の燃料電池セルは、固体電解質の一面に空気極、多面に燃料極が形成されたものであれば良く、上記構造に限定されるものではない。
【００３４】
【実施例】
参考例１
純度が９９．９％で平均粒子径が０．５μｍのＺｒＯ₂（Ｙ₂Ｏ₃１０モル％含有）粉末、純度が９９．８％で平均粒子径が２μｍのＬａ_0.9Ｓｒ_0.1ＭｎＯ₃の空気極粉末をそれぞれ準備した。また、Ｎｉ、Ｃｏ、Ｆｅ、Ｒｕの一種と、Ｚｒ、Ｃｅ、Ｙ、Ｙｂ、Ｓｃ、Ｓｍ、ＮｄおよびＤｙの一種以上を含有するオクチル酸塩をトルエンに溶解させた溶液も合わせて準備した。上記の０．５μｍのＺｒＯ₂粉末をプレス成形した後、大気中１５００℃で３時間焼成して、理論密度比９９．５％以上の厚み０．３ｍｍ、直径３０ｍｍの固体電解質円板を作製した。その後、この固体電解質円板の一方の面に平均粒子径が２μｍのＬａ_0.9Ｓｒ_0.1ＭｎＯ₃ペーストを塗布して、大気中１２００℃で２時間熱処理して固体電解質への焼き付けを行い空気極を形成した。また、上記オクチル酸塩をトルエンに溶解した溶液を、表１および表２に示す組成になるように調整した後、固体電解質の一面に塗布し、大気中１２００℃で２時間熱処理して熱分解を行なわせて燃料極を形成した。例えば、試料Ｎｏ．６では、Ｎｉ、Ｚｒ、Ｙをそれぞれ含有するオクチル酸塩を、Ｎｉが８０重量％、ＺｒＯ₂を２０重量％からなり、ＺｒＯ₂中にＹ₂Ｏ₃が１０モル％含有するようにトルエンに溶解した溶液を用いて燃料極を作製した。この際、空気極および燃料極の厚みをそれぞれ約５０μｍとした。
【００３５】
発電は上述の固体電解質の空気極側に酸素を、燃料極側に水素を流し、１０００℃で発電を行い、１００時間後の出力密度と、１００時間後の出力密度に対する３０００時間後の出力密度の低下率を求めた。
【００３６】
この実験においては、比較のため従来のボ−ルミルにより混合した平均粒子径が５μｍのＮｉＯとＺｒＯ₂（１０モル％含有Ｙ₂Ｏ₃）で重量比率がＮｉ：ＺｒＯ₂＝８０：２０の混合粉末を燃料極として用いた（試料Ｎｏ．１）。また、平均粒子径が５μｍのＮｉＯ粉末と、Ｙ、Ｚｒを含有するオクチル酸塩からなる溶液を用い、該溶液に前記ＮｉＯ粉末を分散させ、これを固体電解質の一面に塗布した後、大気中１２００℃で２時間熱処理して熱分解を行なわせて燃料極を形成した（試料Ｎｏ．２）。また、金属表面および内部の微粒のセラミック粒子の析出の有無を走査型電子顕微鏡で観察した。これらの結果を表１および表２に示す。
【００３７】
【表１】

【００３８】
【表２】

【００３９】
表１および表２より、金属比率が９９重量％を越える試料Ｎｏ．３は長時間発電による出力密度の低下がやや大きいことが分かる。また、金属比率が５０重量％より小さな試料Ｎｏ．１０、１２、４６では出力密度の低下は小さいものの、電気伝導性がやや低いため出力密度の絶対値が小さいことが分かる。それに対して、金属比率が５０〜９９重量％の範囲のものは全て出力密度も高く低下率も小さかった。また、走査型電子顕微鏡による観察から試料Ｎｏ．３〜４６については全て金属粒子の表面および内部に微粒のセラミック粒子の析出が観察された。
【００４０】
実施例１
純度が９９．９％で平均粒子径が３μｍのＺｒＯ₂（１０モル％含有Ｙ₂Ｏ₃、Ｙｂ₂Ｏ₃）粉末に約５〜３０体積％のフロ−ビ−ズ（商品名）のポア形成剤を添加して混合した後、参考例１の片面に空気極が形成された固体電解質円板の一面に塗布し、大気中１４００℃で２時間熱処理して固体電解質表面に厚み約５０μｍの粗粒セラミックからなる多孔質体（骨格）を形成した。この多孔質体の空孔中に表３の組成になるように参考例１のＮｉ、Ｃｏ、Ｆｅ、Ｒｕの一種と、Ｚｒ、Ｃｅ、Ｙ、Ｙｂ、Ｓｃ、Ｓｍの一種以上を含有するオクチル酸塩をトルエンに溶解させた溶液を注入した後、大気中１０００℃で２時間熱処理して熱分解を行なわせ燃料極を形成した。この際、表中の骨格を形成している粗粒セラミックの重量比率は１４００℃の熱処理前後の重量変化から求めた。この後参考例１に従い発電試験と微粒のセラミック粒子の観察を行い、結果を表３に示した。
【００４１】
【表３】

【００４２】
この表３より、金属比率が５０重量％より小さな試料Ｎｏ．５３では出力密度の低下は小さいものの、電気伝導性が低いため出力密度の絶対値がやや小さいことが分かる。また、微粒のセラミック粒子が２０重量％を越える試料Ｎｏ．５５および６７では出力密度の絶対値がやや小さいことが分かる。また、走査型電子顕微鏡による観察から本発明の試料については全て金属粒子の表面および内部に微粒のセラミック粒子の析出が観察された。
【００４３】
参考例２
純度が９９．９％で平均粒子径がそれぞれ５μｍのＺｒＯ_２（１０モル％含有Ｙ_２Ｏ_３、Ｙｂ_２Ｏ_３）粉末と、ＣｅＯ_２粉末と、ＮｉＯ、ＣｏＯ、ＦｅＯ、Ｒｕ粉末と、約５〜３０体積％のフロ−ビ−ズ（商品名）のポア形成剤とを、表４の組成となるように混合した後、参考例１の片面に空気極が形成された固体電解質円板の一面に塗布し、１４００℃で２時間熱処理して固体電解質表面に厚み約５０μｍのＮｉＯ、ＣｏＯ、ＦｅＯ、Ｒｕを含有した粗粒セラミックからなる骨格を形成した。
【００４４】
この骨格中に表４の組成になるようにＺｒ、Ｃｅ、Ｙ、Ｙｂ、Ｓｃ、Ｓｍを含有するオクチル酸塩をトルエンに溶解した溶液を注入した後、大気中１０００℃で２時間熱処理して熱分解を行なわせＮｉＯ、ＣｏＯ、ＦｅＯ、Ｒｕ表面に微粒のセラミックを析出させて燃料極を形成した。この際、表中の骨格を形成している粗粒セラミック、金属の重量比率は１４００℃の熱処理前後の重量変化から求めた。この後、参考例１に従い発電試験と微粒のセラミック粒子の観察を行い、結果を表４に示した。
【００４５】
【表４】

【００４６】
この表４より、金属比率が９５重量％を越え、また粗粒のセラミック粒子の比率が４重量％を下回る試料Ｎｏ．６８では出力密度の低下率がやや大きいことが分かる。また、金属比率が５０重量％より小さな試料Ｎｏ．７４では出力密度の低下は小さいものの、電気伝導性が低いため出力密度の絶対値がやや小さいことが分かる。また、微粒のセラミック粒子が２０重量％を越える試料Ｎｏ．７６では出力密度の絶対値がやや小さいことが分かる。また、走査型電子顕微鏡による観察から試料については全て金属粒子の表面に微粒のセラミック粒子の析出が観察された。
【００４７】
実施例２
参考例１、実施例１および参考例２で作製した試料を室温から１００℃／ｈの速度で１０００℃まで昇温し、１０００℃で１時間保持した後室温まで１００℃／ｈの速度で冷却した。この温度変化を１サイクルとし、２０サイクル繰り返した後実施例１に従い発電試験を行ない、出力密度を求めた。この結果を表５に示す。
【００４８】
【表５】

【００４９】
この表５により燃料極中に粗粒のセラミックの骨格を形成した全ての試料は骨格形成がない試料Ｎｏ．８８、８９に比較して熱処理後の出力密度の低下が少ないことがわかる。発電試験後、骨格形成がない燃料極試料Ｎｏ．８８、８９には剥離が認められたが、骨格を形成した試料には剥離が認められなかった。
【００５０】
実施例３
純度が９９．９％で平均粒子径が８μｍのＬａ_０．９Ｃａ_０．１ＭｎＯ_３粉末を用いて押し出し成形法により一端を封じた中空の円筒状成形体を作製し、１５００℃で３時間焼成して開気孔率３２％で、厚み２ｍｍ，外径１５ｍｍ、長さ２００ｍｍの空気極支持管を作製した。この後、溶射法にて空気極支持管表面に厚みがそれぞれ約５０μｍのＺｒＯ_２（１０モル％Ｙ_２Ｏ_３含有）電解質およびＬａ_０．９Ｃａ_０．１ＣｒＯ_３のインターコネクタを形成した後、固体電解質表面に本発明の燃料極を７０μｍの厚みに形成し、円筒型セルを作製した。発電は、空気極支持管の内側に空気を、外側に水素を流し１０００℃で約５０００時間発電を行ない出力密度の時間変化を観察した。結果を図５に示す。
【００５１】
この図５から、参考例１の試料Ｎｏ．６、実施例１の試料Ｎｏ．６１、参考例２の試料Ｎｏ．８５では、従来のセルの試料Ｎｏ．１および２に比較して出力密度の低下が極めて小さいことがわかる。この結果から本発明の円筒型燃料電池セルは出力密度の高い長期安定性の優れたセルであることが判る。
【００５２】
【発明の効果】
本発明の固体電解質型燃料電池セルでは、燃料極中において、セラミック粒子により形成された骨格（多孔質体）の空孔内に、表面と内部に微粒のセラミック粒子を析出させた金属粒子を含浸、分散させることにより、飛躍的に金属の凝集や粒成長が抑制されるとともに、燃料極の固体電解質への付着強度が向上し、その結果出力密度が向上すると同時に、熱サイクルに対しても安定した出力を示すことができる。
【図面の簡単な説明】
【図１】本発明の円筒型固体電解質型燃料電池セルを示す斜視図である。
【図２】本発明の平板型固体電解質型燃料電池セルを示す斜視図である。
【図３】燃料極が、表面および内部に微粒のセラミック粒子が析出した金属粒子により構成されている状態を示す概念図である。
【図４】燃料極が、セラミック粒子を骨格とする多孔質体の空孔内に、表面および／または内部に微粒のセラミック粒子が析出した金属粒子を分散して構成した状態を示す概念図である。
【図５】出力密度の時間変化を示すグラフである。
【符号の説明】
１・・・支持管
２・・・空気極
３・・・固体電解質
４・・・燃料極
５・・・集電部材
３１・・・金属粒子
３３、３７・・・微粒のセラミック粒子
３５・・・粗粒のセラミック粒子
３６・・・多孔質体（骨格）
３９・・・金属[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid oxide fuel cell and a method for manufacturing the same, and particularly to improvement of a fuel electrode.
[0002]
[Prior art]
Conventionally, a solid oxide fuel cell has a high power generation efficiency because its operating temperature is as high as 1000 to 1050 ° C., and is expected as a third generation power generation system.
[0003]
In general, cylindrical and flat plate types are known as solid oxide fuel cells. The flat fuel cell has a feature that the power density per unit volume of power generation is high, but there are problems such as imperfect gas seal and non-uniform temperature distribution in the cell for practical use. On the other hand, the cylindrical fuel cell has the characteristics that the mechanical strength of the cell is high and the temperature in the cell can be kept uniform although the output density is low. Both types of solid oxide fuel cells are actively researched and exploited, taking advantage of their respective characteristics.
[0004]
As shown in FIG. 1, a single cell of a cylindrical fuel cell has a support tube 1 made of CaO-stabilized ZrO ₂ having an open porosity of about 40%, and a porous air electrode 2 made of a LaMnO ₃ based material thereon. The surface thereof is covered with a solid electrolyte ₃ made of Y ₂ O ₃ stabilized ZrO _2, and a porous Ni-zirconia fuel electrode 4 is provided on this surface. In the fuel cell module, each single cell is connected by Ni felt through an interconnector 5 made of a LaCrO ₃ material in which Ca, Sr and Mg are dissolved. In such power generation of the fuel cell, each unit cell is maintained at a temperature of about 1000 ° C., and air (oxygen) 6 is supplied inside the support tube 1 and fuel gas 7 such as hydrogen or city gas is supplied outside. Is done.
[0005]
In recent years, an attempt has been made to directly use a LaMnO ₃ -based material, which is an air electrode material, as a porous support tube in order to simplify the process in the cell manufacturing process. As a support tube material having a function as an air electrode, a LaMnO ₃ solid solution material in which La is substituted with Ca or Sr by 10 to 20 atomic% is used.
[0006]
Further, the single cell of the flat plate fuel cell uses the same material system as that of the cylindrical cell, and as shown in FIG. 2, a porous air electrode 9 is provided on one side of the solid electrolyte 8 and a porous fuel electrode 10 is provided on the other side. Is provided. For the connection between the single cells, a dense LaCrO ₃ material to which Mg or Ca called separator 11 is added is used.
[0007]
The fuel electrodes of the above-described cylindrical and flat-plate type solid oxide fuel cells generally include Ni powder and ZrO ₂ (containing Y ₂ O ₃ ) powder or NiO powder and ZrO ₂ (containing Y ₂ O ₃ ). The powder mixed powder was applied to the surface of the solid electrolyte by a screen printing method, or dipped in a solution containing the mixed powder, and then dried to form a fuel electrode. In the case of the latter NiO / ZrO ₂ (containing Y ₂ O ₃ ) powder, it was heat-treated in a reducing atmosphere at 1000 to 1400 ° C. to form a fuel electrode.
[0008]
[Problems to be solved by the invention]
However, the fuel electrode produced by these methods has a large problem that the power generation performance deteriorates due to aggregation or grain growth of Ni (NiO is reduced to Ni during power generation) during long-time power generation.
[0009]
In recent years, in order to solve this problem, as disclosed in JP-A-7-22032, an organometallic compound such as octylate or naphthenate containing Zr and Y elements is thermally decomposed to obtain Ni or the like. A method has been proposed in which fine ZrO ₂ (containing Y ₂ O ₃ ) ceramic particles are deposited on the surface of metal particles to suppress performance degradation due to Ni aggregation and sintering. It was not enough to prevent settling.
[0010]
[Means for Solving the Problems]
As a result of examining the above problems, the present invention forms a skeleton with ceramic particles, and in the pores of the skeleton, metal particles having fine ceramic particles precipitated on the surface and inside are dispersed. The present inventors have found that the effect of suppressing the aggregation and sintering of metals can be improved, and the adhesion strength of the fuel electrode to the solid electrolyte can also be improved.
[0011]
That is, the solid oxide fuel cell according to the present invention is a solid oxide fuel cell in which a porous air electrode is formed on one side of the solid electrolyte and a porous fuel electrode is formed on the other side. The metal particles having fine ceramic particles deposited on the surface and inside thereof are dispersed in the pores of the porous body having the skeleton.
[0012]
The method for producing a solid oxide fuel cell according to the present invention is a method for producing a solid oxide fuel cell in which a porous air electrode is formed on one surface of the solid electrolyte and a porous fuel electrode is formed on the other surface. The fuel electrode is made of an organic metal compound solution containing at least one metal element of Ni, Co, Fe, and Ru, and Zr and / or Ce. This is a method in which metal particles having fine ceramic particles precipitated on the surface and inside are dispersed in the pores of the porous body by being injected into the pores and thermally decomposed.
[0014]
[Action]
In the solid oxide fuel cell of the present invention, metal particles having fine ceramic particles deposited on the surface and inside are dispersed in the pores of the skeleton (porous body) formed of ceramic particles. Aggregation and grain growth of the fuel electrode are suppressed, and the adhesion strength of the fuel electrode to the solid electrolyte is improved. As a result, the output density is improved, and moreover, a stable output can be obtained with respect to the thermal cycle.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 4, the basic structure of the fuel electrode in the solid oxide fuel cell of the present invention is in the pores of a porous body (skeleton) 36 composed of coarse ceramic particles 35 on the surface of the solid electrolyte 3. The metal 39 in which fine ceramic particles 37 are deposited in the form of a film and / or particles on the surface and inside is dispersed.
[0016]
In such a fuel electrode 4, since the coarse ceramic particles 35 form a skeleton, the adhesion strength of the fuel electrode 4 to the solid electrolyte 3 is high, and separation of the fuel electrode 4 due to the temperature cycle is extremely reduced. High power density. Both the ceramic particles 35 and the fine ceramic particles 37 forming the skeleton contain ZrO ₂ , CeO ₂ alone, or a solid solution thereof, or rare earth element oxides such as Y, Yb, Sc, Sm, Nd, Dy, and Pr. It is preferably composed of ZrO ₂ and CeO ₂ .
[0017]
In this case, the range of 50 to 95% by weight of metal (as metal), 1 to 20% by weight of fine ceramic particles, and 4 to 30% by weight of coarse ceramic particles is excellent. When the amount of metal is more than 95% by weight, or the amount of fine ceramic particles is less than 1% by weight, or the amount of coarse ceramic particles is less than 4% by weight, the effect of suppressing metal aggregation and grain growth during power generation Is small. In addition, when the metal content is less than 50% by weight, when the fine ceramic particles are more than 20% by weight, or when the coarse ceramic particles are more than 30% by weight, the electrical conductivity is lowered and the power generation performance is reduced. It tends to get worse. Particularly, the range of 60 to 80% by weight of metal (as metal), 10 to 20% by weight of fine ceramic particles, and 10 to 20% by weight of coarse ceramic particles is excellent.
[0018]
The size of the coarse ceramic particles forming the skeleton is excellent in the range of 0.5 to 30 μm, particularly 2 to 10 μm, in terms of average particle diameter. Further, the primary particle size of the fine ceramic particles is excellent in the range of 0.01 to 0.5 μm, particularly 0.1 to 0.5 μm in average particle diameter.
[0019]
Such a ceramic skeleton in the fuel electrode is obtained by first coating coarse ceramic particles on the surface of the solid electrolyte by a known technique such as screen printing or slurry dipping, and then in an oxidizing atmosphere at 1000 to 1700 ° C., preferably It is formed by heat treatment at a temperature of 1200 to 1400 ° C. for 1 to 10 hours. Thereafter, an organometallic compound solution containing the metallic elements of Ni, Co, Fe, Ru and Zr and / or Ce at the same time, for example, octylate, naphthenate, neodecanoate, ethylhexanoate, propionic acid After the skeleton is impregnated with a solution in which a salt is dissolved in a solvent such as toluene, it is thermally decomposed at a temperature of 400 to 1600 ° C. in an oxidizing atmosphere to deposit fine ceramics on the metal surface and inside, thereby forming a fuel electrode. It is formed. In addition, after thermal decomposition, fine ceramic particles are deposited on the surface and inside of the metal oxide, but the metal oxide becomes metal particles by the subsequent reduction treatment.
[0022]
As the metal component in the fuel electrode, in addition to the above-mentioned oxides such as Ni and Co, carbonates, acetates, odorates and the like that form oxides by heat treatment can also be used.
[0023]
In the above method, the organometallic compound solution may contain an element selected from Y and rare earth elements in addition to Zr and / or Ce.
[0024]
As the fuel electrode in the solid oxide fuel cell, as shown in FIG. 3, for example, the fuel electrode 4 on the surface of the solid electrolyte 3 is formed of metal particles 31 such as Ni on the surface of fine ceramic particles 33 and / or fine particles. Precipitated in a state, and further fine ceramic particles 33 are precipitated inside. The primary particle diameter of the fine ceramic particles 33 varies depending on the preparation conditions such as heat treatment conditions, but the average particle diameter is about 0.01 to 0.5 μm. The average particle diameter of the metal particles is preferably 1 to 20 μm, and 5 to 10 μm from the viewpoint of electrical conductivity and gas permeability.
[0025]
In the fuel electrode 4 of FIG. 3, as the metal particles 31, Ni, Co, Fe, Ru, or an alloy thereof is used. The fine ceramic particles 33 include ZrO ₂ , CeO ₂ alone, and solid solutions thereof, as well as ZrO containing 1 to 30 mol% of rare earth elements such as Y, Yb, Sc, Sm, Nd, Dy, and Pr. _Two solid solutions or a CeO ₂ solid solution, and a solid solution of ZrO ₂ and CeO ₂ containing Y or a rare earth element can be used. Among these, from the viewpoint of economy, the fuel electrode material is preferably Ni and ZrO ₃ (containing Y ₂ O ₃ ) or a combination of Ni and CeO ₂ .
[0026]
Such a fuel electrode structure includes an organometallic compound solution containing, for example, Ni, Co, Fe, Ru metal elements and Zr and / or Ce simultaneously, such as octylate, naphthenate, neodecanoate, ethyl A solution prepared by dissolving hexanoate, propionate or the like in a solvent such as toluene is applied to the surface of the solid electrolyte by a known technique such as screen printing or slurry dipping, and then at a temperature of 400 to 1600 ° C. in an oxidizing atmosphere. It is produced by thermal decomposition for 1 to 10 hours. The organometallic compound solution may contain an element selected from Y and rare earth elements. In the heat treatment in an oxidizing atmosphere, Ni, Co, and Fe metals are oxidized, and thus reprocessing in a reducing atmosphere is necessary. In order to reduce the metal oxide, it is desirable to perform heat treatment in N ₂ and Ar having an oxygen concentration of 1% or less.
[0027]
In order to deposit fine ceramic particles 33 on and inside the metal particles 31 such as Ni, it is necessary to use an organometallic compound solution containing metal particles such as Ni and Zr and / or Ce simultaneously .
[0028]
In the fuel electrode shown in FIG. 3, the weight ratio of Ni, Co, Fe, Ru metal and the oxide composed of Y and rare earth elements is 99-50 wt% in terms of metal for Ni, Co, Fe, Ru. Zr and / or Ce oxide (including the case of containing Y and rare earth elements) is preferably in the range of 1 to 50% by weight. When the metal such as Ni is more than 99% by weight, the aggregation or grain growth of the metal during power generation cannot be sufficiently suppressed. On the other hand, when the metal such as Ni is less than 50% by weight, the electric conductivity tends to be lowered and the power generation performance tends to be deteriorated. The weight ratio of these metals and oxides is particularly preferably 80 to 90% by weight of metal, and 10 to 20% by weight of oxides of Zr and / or Ce (including cases where Y and rare earth elements are contained).
[0029]
Further, the thickness of the fuel electrode is excellent in the range of 20 to 200 μm in the case of a flat plate cell and in the range of 30 to 300 μm in the case of a cylindrical cell, from the viewpoints of electrical conductivity and gas permeability.
[0030]
The structure of the cylindrical fuel cell constructed according to the present invention is, for example, as shown in FIG. 1, with Y ₂ O ₃ or CaO-stabilized ZrO ₂ having an open porosity of about 40% as the support tube 1, and on top of it. A LaMnO ₂ -based material in which La is replaced with Ca and Sr as a porous air electrode 2 by a slurry dip method is applied, and a solid electrolyte is formed on the surface by a vapor phase synthesis method (EVD) or a thermal spraying method. 4 is coated with a Y ₂ O ₃ stabilized ZrO ₂ film or a CeO ₂ film containing Y ₂ O ₃ , Yb ₂ O ₃ or CaO, and a porous fuel electrode 4 of FIG. Is formed. In the fuel cell of the present invention, an air electrode made of LaMnO ₃ in which La is replaced by 10 to 20 atomic% with Ca and Sr may be used as the support tube without using the support tube.
[0031]
The current collector called the interconnector 5 is formed such that LaCrO ₃ to which 5 to 20 mol% of CaO and MgO is added is in contact with the air electrode by using a vapor phase synthesis method or a thermal spraying method.
[0032]
Also, a flat plate cell can be manufactured as shown in FIG. 2 using the same material as that of the cylindrical cell.
[0033]
The fuel cell of the present invention is not limited to the above structure as long as the air electrode is formed on one surface of the solid electrolyte and the fuel electrode is formed on many surfaces.
[0034]
【Example】
Reference example 1
ZrO ₂ (containing 10 mol% Y ₂ O ₃ ) powder having a purity of 99.9% and an average particle diameter of 0.5 μm, La _0.9 Sr _0.1 MnO ₃ air having a purity of 99.8% and an average particle diameter of 2 μm Each pole powder was prepared. Further, a solution in which octylate containing one kind of Ni, Co, Fe, and Ru and one or more kinds of Zr, Ce, Y, Yb, Sc, Sm, Nd, and Dy was dissolved in toluene was also prepared. The above 0.5 μm ZrO ₂ powder was press-molded and then fired in the atmosphere at 1500 ° C. for 3 hours to produce a solid electrolyte disk having a theoretical density ratio of 99.5% or more and a thickness of 0.3 mm and a diameter of 30 mm. . After that, La _0.9 Sr _0.1 MnO ₃ paste having an average particle diameter of 2 μm is applied to one surface of the solid electrolyte disk, and heat treatment is performed at 1200 ° C. for 2 hours in the atmosphere to be baked on the solid electrolyte, and the air electrode is formed. Formed. Moreover, after adjusting the solution which melt | dissolved the said octylate in toluene so that it might become a composition shown in Table 1 and Table 2, it apply | coated to one side of solid electrolyte, and heat-processes at 1200 degreeC in air | atmosphere for 2 hours, and thermal decomposition The fuel electrode was formed. For example, sample No. In No. 6, octylate containing Ni, Zr, and Y, respectively, was added to toluene so that Ni was 80 wt% and ZrO ₂ was 20 wt%, and Y ₂ O ₃ was contained in ZrO ₂ at 10 mol%. A fuel electrode was prepared using the dissolved solution. At this time, the thickness of the air electrode and the fuel electrode was about 50 μm, respectively.
[0035]
For power generation, oxygen is supplied to the air electrode side of the above solid electrolyte, hydrogen is supplied to the fuel electrode side, power is generated at 1000 ° C., and the output density after 100 hours and the output density after 3000 hours with respect to the output density after 100 hours. The reduction rate of was determined.
[0036]
In this experiment, for comparison, a mixture of NiO and ZrO ₂ (Y ₂ O ₃ containing 10 mol%) having an average particle diameter of 5 μm and a weight ratio of Ni: ZrO ₂ = 80: 20 mixed by a conventional ball mill. Powder was used as a fuel electrode (Sample No. 1). Also, using a solution composed of NiO powder having an average particle size of 5 μm and octylate containing Y and Zr, the NiO powder was dispersed in the solution, and this was applied to one surface of the solid electrolyte, and then in the atmosphere. A heat electrode was formed by heat treatment at 1200 ° C. for 2 hours to form a fuel electrode (Sample No. 2). Further, the presence or absence of precipitation of fine ceramic particles on the metal surface and inside was observed with a scanning electron microscope. These results are shown in Tables 1 and 2.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
From Tables 1 and 2, Sample No. with a metal ratio exceeding 99% by weight was obtained. It can be seen that No. 3 shows a slight decrease in output density due to long-time power generation. Sample No. with a metal ratio smaller than 50% by weight was used. In 10, 12, and 46, although the decrease in output density is small, it can be seen that the absolute value of output density is small because the electrical conductivity is slightly low. On the other hand, all the metal ratios in the range of 50 to 99% by weight had a high output density and a small decrease rate. In addition, from observation with a scanning electron microscope, the sample No. In all of Nos. 3 to 46, precipitation of fine ceramic particles was observed on the surface and inside of the metal particles.
[0040]
Example 1
A pore of about 5 to 30% by volume of flow beads (trade name) in a ZrO ₂ (10 mol% containing Y ₂ O ₃ , Yb ₂ O ₃ ) powder having a purity of 99.9% and an average particle diameter of 3 μm After adding and mixing the forming agent, it was applied to one surface of a solid electrolyte disk having an air electrode formed on one side of Reference Example 1, and heat-treated at 1400 ° C. in the atmosphere for 2 hours to have a thickness of about 50 μm on the surface of the solid electrolyte. A porous body (skeleton) made of coarse-grained ceramic was formed. Octyl containing one type of Ni, Co, Fe, Ru of Reference Example 1 and one or more types of Zr, Ce, Y, Yb, Sc, Sm so that the pores of this porous body have the composition shown in Table 3 After injecting a solution obtained by dissolving an acid salt in toluene, heat treatment was performed in the atmosphere at 1000 ° C. for 2 hours to perform thermal decomposition to form a fuel electrode. At this time, the weight ratio of the coarse-grained ceramic forming the skeleton in the table was determined from the change in weight before and after the heat treatment at 1400 ° C. Thereafter, a power generation test and observation of fine ceramic particles were performed according to Reference Example 1, and the results are shown in Table 3.
[0041]
[Table 3]

[0042]
From Table 3, sample No. with a metal ratio smaller than 50% by weight is obtained. 53, although the decrease in output density is small, it can be seen that the absolute value of the output density is slightly small because of low electrical conductivity. Sample Nos. With fine ceramic particles exceeding 20% by weight. 55 and 67 show that the absolute value of the output density is slightly small. In addition, from the observation with a scanning electron microscope, in all the samples of the present invention, precipitation of fine ceramic particles was observed on the surface and inside of the metal particles.
[0043]
Reference example 2
ZrO ₂ (10 mol% containing Y ₂ O ₃ , Yb ₂ O ₃ ) powder having a purity of 99.9% and an average particle diameter of 5 μm, CeO ₂ powder, NiO, CoO, FeO, Ru powder, A solid electrolyte disc in which 5 to 30% by volume of a flow bead (trade name) pore-forming agent was mixed so as to have the composition shown in Table 4, and then an air electrode was formed on one side of Reference Example 1. A skeleton made of coarse ceramics containing NiO, CoO, FeO and Ru having a thickness of about 50 μm was formed on the surface of the solid electrolyte by heat treatment at 1400 ° C. for 2 hours.
[0044]
After injecting a solution of octylate containing Zr, Ce, Y, Yb, Sc, Sm in toluene into this skeleton so as to have the composition shown in Table 4, heat treatment was performed at 1000 ° C. for 2 hours in the atmosphere. Thermal decomposition was performed to deposit fine ceramics on the surfaces of NiO, CoO, FeO, and Ru to form a fuel electrode. At this time, the weight ratio of the coarse-grained ceramic and metal forming the skeleton in the table was determined from the weight change before and after the heat treatment at 1400 ° C. Thereafter, a power generation test and observation of fine ceramic particles were performed according to Reference Example 1, and the results are shown in Table 4.
[0045]
[Table 4]

[0046]
According to Table 4, the sample No. in which the metal ratio exceeds 95% by weight and the ratio of coarse ceramic particles is less than 4% by weight. It can be seen that the decrease rate of the output density is slightly large at 68. Sample No. with a metal ratio smaller than 50% by weight was used. In 74, although the decrease in the output density is small, it can be seen that the absolute value of the output density is slightly small because the electrical conductivity is low. Sample Nos. With fine ceramic particles exceeding 20% by weight. 76 shows that the absolute value of the output density is slightly small. In addition, from the observation with the scanning electron microscope, precipitation of fine ceramic particles was observed on the surface of the metal particles for all the samples .
[0047]
Example 2
The samples prepared in Reference Example 1, Example 1 and Reference Example 2 were heated from room temperature to 1000 ° C. at a rate of 100 ° C./h, held at 1000 ° C. for 1 hour, and then cooled to room temperature at a rate of 100 ° C./h. did. This temperature change was defined as one cycle, and after 20 cycles were repeated, a power generation test was performed according to Example 1 to determine the output density. The results are shown in Table 5.
[0048]
[Table 5]

[0049]
According to Table 5, all samples in which a coarse-grained ceramic skeleton was formed in the fuel electrode showed no sample no. It can be seen that the decrease in the output density after heat treatment is less than that of 88 and 89. After the power generation test, the fuel electrode sample no. Although peeling was observed in 88 and 89, peeling was not recognized in the sample in which the skeleton was formed.
[0050]
Example 3
A hollow cylindrical molded body having one end sealed by an extrusion method using La _0.9 Ca _0.1 MnO ₃ powder having a purity of 99.9% and an average particle diameter of 8 μm was produced at 1500 ° C. for 3 hours. Baking was performed to produce an air electrode support tube having an open porosity of 32%, a thickness of 2 mm, an outer diameter of 15 mm, and a length of 200 mm. After that, after forming an ZrO ₂ (containing 10 mol% Y ₂ O ₃ ) electrolyte and an La _0.9 Ca _0.1 CrO ₃ interconnector having a thickness of about 50 μm on the surface of the air electrode support tube by thermal spraying, The fuel electrode of the present invention was formed to a thickness of 70 μm on the surface of the solid electrolyte to produce a cylindrical cell. For power generation, air was flown inside the air electrode support tube and hydrogen was flown outside, and power generation was performed at 1000 ° C. for about 5000 hours, and the change in power density with time was observed. The results are shown in FIG.
[0051]
From FIG. 5, the sample No. 6. Sample No. 1 of Example 1 61, a sample of Reference Example 2 No. 85, the conventional cell sample No. It can be seen that the decrease in output density is extremely small compared to 1 and 2. From this result, it can be seen that the cylindrical fuel cell of the present invention is a cell having high output density and excellent long-term stability.
[0052]
【The invention's effect】
In the solid oxide fuel cell according to the present invention, the fuel electrode is impregnated with metal particles in which fine ceramic particles are deposited on the surface and inside the pores of the skeleton (porous body) formed by the ceramic particles. By dispersing, the metal agglomeration and grain growth are drastically suppressed, and the adhesion strength of the fuel electrode to the solid electrolyte is improved. As a result, the power density is improved and at the same time stable against thermal cycles. Output can be shown.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a cylindrical solid oxide fuel cell according to the present invention.
FIG. 2 is a perspective view showing a flat plate solid oxide fuel cell according to the present invention.
FIG. 3 is a conceptual diagram showing a state in which a fuel electrode is composed of metal particles having fine ceramic particles deposited on the surface and inside.
FIG. 4 is a conceptual diagram showing a state in which a fuel electrode is configured by dispersing metal particles having fine ceramic particles deposited on the surface and / or inside thereof in pores of a porous body having ceramic particles as a skeleton. is there.
FIG. 5 is a graph showing a change in output density with time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Support tube 2 ... Air electrode 3 ... Solid electrolyte 4 ... Fuel electrode 5 ... Current collecting member 31 ...

Metal particle

33, 37 ... Fine ceramic particle 35 ...・ Coarse ceramic particles 36 ... porous body (skeleton)
39 ... Metal

Claims

In a solid electrolyte type fuel cell in which a porous air electrode is formed on one side of a solid electrolyte and a porous fuel electrode is formed on the other side, the fuel electrode is placed in a pore of a porous body having ceramic particles as a skeleton. A solid oxide fuel cell comprising a dispersion of metal particles having fine ceramic particles deposited on the surface and inside .

A method of manufacturing a solid oxide fuel cell in which a porous air electrode is formed on one side of a solid electrolyte and a porous fuel electrode is formed on the other side, wherein the fuel electrode is made of Ni, Co, Fe and Ru An organometallic compound solution containing at least one metal element and Zr and / or Ce is injected into the pores of the porous body having ceramic particles as a skeleton, and thermally decomposed. A method for producing a solid oxide fuel cell, characterized in that metal particles having fine ceramic particles deposited on the surface and inside thereof are dispersed in the pores.