JP3871903B2

JP3871903B2 - Method for introducing electrode active oxide into fuel electrode for solid oxide fuel cell

Info

Publication number: JP3871903B2
Application number: JP2001161837A
Authority: JP
Inventors: 玲一千葉; 文一吉村; 庸司櫻井
Original assignee: Nippon Telegraph and Telephone Corp
Current assignee: Nippon Telegraph and Telephone Corp
Priority date: 2001-05-30
Filing date: 2001-05-30
Publication date: 2007-01-24
Anticipated expiration: 2021-05-30
Also published as: JP2002352809A

Description

【０００１】
【産業上の利用分野】
本発明は、固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法に関するものである。
【０００２】
【従来の技術および問題点】
近年、酸素イオン伝導体を用いた固体電解質型燃料電池に関心が高まりつつある。特にエネルギーの有効利用という観点から、固体燃料電池はカルノー効率の制約を受けないため本質的に高いエネルギー変換効率を有し、さらに良好な環境保全が期待されるなどの優れた特長を持っている。
【０００３】
しかしながら、固体電解質型燃料電池は、主要部分がセラミックで構成されているため、製造コストが高い。これが固体電解質型燃料電池の普及を妨げている。ここで、この電池の動作温度を現在の１０００℃から８００℃またはそれ以下にすることで、金属の使用が可能となる。これにより、主要な体積を占めるインターコネクタ部分を安価な金属に替えることができ、大幅なコスト低減に繋がる。
【０００４】
この低温化を目的として電解質のイオン電導度の向上、電解質の薄膜化などが検討されている。固体電解質としては、希土類添加ジルコニア（（１−ｘ）ＺｒＯ_2-xＡ₂Ｏ₃，ＡはＬａ，Ｐｒ，Ｃｅ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｙｂ，Ｌｕ，Ｙ，Ｓｃ，Ａｌ，Ｇａなどの元素で、０．０２５≦ｘ≦０．１５）を使用しそれの薄層化や、イオン伝導度の高いＳｃ添加系ジルコニア電解質材料、またはランタンガレート系電解質Ｌｎ_1-xＡ_xＢ_1-yＭｇ_yＯ₃（ＬｎはＬａ，Ｐｒ，Ｎｄ，Ｓｍなどの元素でＡはＳｒ、Ｃａ、Ｂａなど、ｘが０．０５≦ｘ≦０．２、ＢはＧａ、Ａｌなどで、Ｍｇの総量ｙは０．０５≦ｙ≦０．３）が主に検討されている。これらの他に、燃料極などの電極の性能の大幅な向上が必要である。これは、低温化により電気化学反応速度が急激に低下するためである。
【０００５】
燃料電池セルは、電解質を挟んで空気極と燃料極が設けられているが、これらの電極は、ガスと電子を電解質まで供給し、電解質との界面において電気化学反応を起こす場を提供している。この反応場は、ガスと電子そしてイオンが接するため三相界面と呼ばれている。
【０００６】
燃料極にはＮｉＯ−ＹＳＺすなわち電子伝導体であるＮｉと酸素イオン伝導体であるＹＳＺ（０．９２ＺｒＯ₂−０．０８Ｙ₂Ｏ₃）の混合物が使用されており、三相界面はＮｉとＹＳＺとの界面にできる。電子と酸素イオンに対して共に伝導体である電極活性酸化物がこの界面に接している場合、反応場、すなわち三相界面が著しく拡大し、電極特性が改善されると言われている。
【０００７】
還元雰囲気中で安定な電極活性酸化物の例として、ＳＤＣ（Ｃｅ_0.8Ｓｍ_0.2Ｏ_1.9）などのセリア系酸化物と（ＬａＳｒ）（ＧａＭｇ）Ｏ₃などのランタンガレート系酸化物のＢサイトにＣｏやＮｉなどの遷移金属を添加した系が知られている。
【０００８】
これらを従来材料であるＮｉＯ−ＹＳＺなどに混合した原料粉末を用いて、燃料極を焼結形成することもできる。しかし、セルを作製する過程で１３００℃程度の高温に曝され、これらの材料と電解質、または燃料極を形成しているＮｉＯなどの酸化物とが反応し界面付近に劣化物を生成する。
【０００９】
たとえばジルコニア系電解質とランタン系ペロブスカイト酸化物では絶縁体のＬａ₂Ｚｒ₂Ｏ₇、またはＳｒＺｒＯ₃、セリア系材料とジルコニア電解質とは酸素イオン電導度が非常に低いＣｅ_0.5Ｚｒ_0.5Ｏ₂を生じる。またランタンガレート系の混合導電体とランタンガレート系の固体電解質とは、固溶体を作り易く、固体電解質内に深く拡散し、電解質のイオン輸率を低下させることがあるため、セル出力電圧の低下を引き起こす。
【００１０】
この様に、セルの電極と電解質は、動作温度の７００℃から１０００℃に比べ、かなり高い温度域についても劣化反応を抑制することが求められ、この結果以上の様な電極活性酸化物の使用が難しい。
【００１１】
【本発明の目的】
本発明は固体電解質用セルの作製法に求められている、燃料極の電極特性を改善するために、混合導電体を電解質との界面付近に導入し且つ劣化物を生じない燃料極の作製方法を提供することを目的とする。
【００１２】
【問題点を解決するための手段】
上記問題点を解決するため、本発明による固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法は、緻密な固体電解質とその両面に設けられた多孔質の燃料極と空気極で構成された燃料電池セルを備えた燃料電池の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法において、前記燃料極及び固体電解質を焼結形成した後、多孔質の燃料極内部に電子伝導と酸素イオン伝導を共に有する電極活性酸化物の材料を有機金属溶液、または無機金属塩溶液の形で含浸させたのち熱分解酸化反応により、所望の組成の電極活性酸化物を電解質との界面付近へ導入する方法であって、前記固体電解質が希土類やＡｌ，Ｇａの群より選択された一種以上を添加したジルコニア系酸化物からなり、前記燃料極が希土類やＡｌ，Ｇａの一種以上を添加したジルコニア系酸化物とＮｉまたはＮｉとＣｏやＦｅとの合金、またはこれらの酸化物との混合体で構成されており、前記電極活性酸化物の組成がＣｅ _１−ｘＬｎ _ｘＯ _{２−ｘ／２} （ＬｎはＹまたは元素周期表のＬａからＬｕの中のＣｅを除くいずれか、またはこれらの中の２種類以上の元素を添加した系で、その総量ｘが０．１≦ｘ≦０．４）であることを特徴とする。さらに、本発明による第２の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法は、緻密な固体電解質とその両面に設けられた多孔質の燃料極と空気極で構成された燃料電池セルを備えた燃料電池の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法において、前記燃料極及び固体電解質を焼結形成した後、多孔質の燃料極内部に電子伝導と酸素イオン伝導を共に有する電極活性酸化物の材料を有機金属溶液、または無機金属塩溶液の形で含浸させたのち熱分解酸化反応により、所望の組成の電極活性酸化物を電解質との界面付近へ導入する方法であって、前記固体電解質がランタンガレート系酸化物からなり、前記燃料極がランタンガレート系酸化物とＮｉまたはＮｉとＣｏやＦｅとの合金、またはこれらの酸化物との混合体で構成されており、前記電極活性酸化物の組成がＣｅ _１−ｘＬｎ _ｘＯ _{２−ｘ／２} （ＬｎはＹまたは元素周期表のＬａからＬｕの中のＣｅを除くいずれか、またはこれらの中の２種類以上の元素を添加した系で、その総量ｘが０．１≦ｘ≦０．４）であることを特徴とする。また、本発明による第３の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法は、緻密な固体電解質とその両面に設けられた多孔質の燃料極と空気極で構成された燃料電池セルを備えた燃料電池の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法において、前記燃料極及び固体電解質を焼結形成した後、多孔質の燃料極内部に電子伝導と酸素イオン伝導を共に有する電極活性酸化物の材料を有機金属溶液、または無機金属塩溶液の形で含浸させたのち熱分解酸化反応により、所望の組成の電極活性酸化物を電解質との界面付近へ導入する方法であって、前記固体電解質が希土類やＡｌ，Ｇａの群より選択された一種以上を添加したジルコニア系酸化物からなり、前記燃料極が希土類やＡｌ，Ｇａの一種以上を添加したジルコニア系酸化物とＮｉまたはＮｉとＣｏやＦｅとの合金、またはこれらの酸化物との混合体で構成されており、前記電極活性酸化物の組成が、（１−ｙ）（Ｚｒ _１−ｘＴｉ _ｘＯ _２）−ｙ（Ｌｎ _２Ｏ _３）（ＬｎはＹ，Ｓｃまたは元素周期表のＧｄからＬｕの中のいずれか、またはこれらの中の２種類以上の元素で、Ｔｉの総量ｘが０．０３≦ｘ≦０．２で、Ｌｎ _２Ｏ _３の総量ｙが０．０３≦ｙ≦０．１５）であることを特徴とする。本発明による第４の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法は、緻密な固体電解質とその両面に設けられた多孔質の燃料極と空気極で構成された燃料電池セルを備えた燃料電池の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法において、前記燃料極及び固体電解質を焼結形成した後、多孔質の燃料極内部に電子伝導と酸素イオン伝導を共に有する電極活性酸化物の材料を有機金属溶液、または無機金属塩溶液の形で含浸させたのち熱分解酸化反応により、所望の組成の電極活性酸化物を電解質との界面付近へ導入する方法であって、前記固体電解質が希土類やＡｌ，Ｇａの群より選択された一種以上を添加したジルコニア系酸化物からなり、前記燃料極が希土類やＡｌ，Ｇａの一種以上を添加したジルコニア系酸化物とＮｉまたはＮｉとＣｏやＦｅとの合金、またはこれらの酸化物との混合体で構成されており、前記電極活性酸化物の組成が、Ｌｎ _１−ｘＣ _ｘＧａ _１−ｙＤ _ｙＯ _３（ＬｎはＬａ，Ｐｒ，Ｎｄ，Ｅｕ，Ｇｄ，Ｔｂの中の一種類以上の元素、ＣはＣａ，Ｓｒ，Ｂａの中の一種類以上の元素、ＤはＭｇ，Ｎｉ，Ｃｏ，Ｆｅ，Ａｌの中の一種類以上の元素、０．０５≦ｘ≦０．２、０．１≦ｙ≦０．３）であることを特徴とする。本発明による第５の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法は、緻密な固体電解質とその両面に設けられた多孔質の燃料極と空気極で構成された燃料電池セルを備えた燃料電池の固体電解質型燃料電池用燃料極への電極活性酸化物の導入方法において、前記燃料極及び固体電解質を焼結形成した後、多孔質の燃料極内部に電子伝導と酸素イオン伝導を共に有する電極活性酸化物の材料を有機金属溶液、または無機金属塩溶液の形で含浸させたのち熱分解酸化反応により、所望の組成の電極活性酸化物を電解質との界面付近へ導入する方法であって、前記固体電解質がランタンガレート系酸化物からなり、前記燃料極がランタンガレート系酸化物とＮｉまたはＮｉとＣｏやＦｅとの合金、またはこれらの酸化物との混合体で構成されており、前記電極活性酸化物の組成が、Ｌｎ _１−ｘＣ _ｘＧａ _１−ｙＤ _ｙＯ _３（ＬｎはＬａ，Ｐｒ，Ｎｄ，Ｅｕ，Ｇｄ，Ｔｂの中の一種類以上の元素、ＣはＣａ，Ｓｒ，Ｂａの中の一種類以上の元素、ＤはＭｇ，Ｎｉ，Ｃｏ，Ｆｅ，Ａｌの中の一種類以上の元素、０．０５≦ｘ≦０．２、０．１≦ｙ≦０．３）であることを特徴とする。
【００１３】
すなわち本発明によれば、燃料極、そして最も高温の焼成過程である固体電解質の焼成が終了した後に、燃料極内に有機金属溶液または無機金属塩溶液の形で電極活性酸化物を形成させる溶液を含浸させる。この後に劣化反応の起きない適当な温度において、燃料極内の液の熱分解酸化反応を生じさせて固体電解質界面付近に所望の混合導電体、すなわち電極活性酸化物を導入するものである。
【００１４】
ここで、セルを作製する方法として、最初に燃料極を形成し、その上に電解質と空気極を形成する場合は、電解質を作製した直後または空気極を作製した後に溶液を含浸させる。燃料極を最後に形成する場合は、燃料極を形成した後に含浸させる。インターコネクタなど全てを一体焼成する場合は、その焼成後に含浸させる。
【００１５】
【作用】
以下に本発明の作用を説明する。
【００１６】
燃料極には、界面での劣化を抑えるため、ジルコニア系固体電解質とジルコニア系の燃料極、またはランタンガレート系固体電解質とランタンガレート系燃料極を用いる。これにより燃料極および固体電解質の焼成は、充分高い温度とすることができ、機械強度の充分に高い燃料極および緻密な固体電解質が得られる。
【００１７】
これらの焼成を終えた後に、有機金属溶液または無機金属塩溶液を燃料極に含浸させる。燃料極は多孔質体とはいえ微細な気孔を有しているため、通常の粉体を溶液に展開したスラリでは電解質界面まで充分に浸透させることが難しい。
【００１８】
しかし、ここで用いる溶液は固形物を含まないため燃料極を浸透し電解質と燃料極の界面付近まで到達する。この溶液が熱分解酸化反応によりＳＤＣなどの電極活性酸化物が生じる。
【００１９】
ここで電極活性酸化物の組成は電極活性酸化物を形成させる溶液に含まれる金属元素の量をあらかじめ制御することで容易に制御することができる。この電極活性酸化物は電子と酸素イオンを共に伝導させることができるため電極反応に寄与する三相界面がこの電極活性酸化物全体に広がる。このため燃料極の電極特性が大幅に向上する。
【００２０】
以上の方法により、セルの製造過程における焼成温度の制約をあまり受けずに電極活性な電極活性酸化物を燃料極内部に導入することができ、高性能な固体電解質型燃料電池用の燃料極を実現できる。
【００２１】
【実施例】
以下に本発明の実施例を説明する。なお、当然のことであるが本発明は以下の実施例に限定されるものではない。
【００２２】
【実施例１】
実施例で使用した燃料電池セルおよびこれを用いて組み立てた燃料電池を図１および図２に示す。図１および図２より明らかなように、緻密な固体電解質１の一方の面に空気極２が、他方の面に燃料極３が形成されており、前記空気極２及び燃料極３には白金の集電メッシュ４が設けられた構造になっている。なお図において、５は白金端子、６はガスシールである。
【００２３】
まずドクターブレード法で焼成した０．２ｍｍ厚でＳｃ₂Ｏ₃、Ａｌ₂Ｏ₃添加ジルコニア（ＳＡＳＺまたは、０．８９５ＺｒＯ₂−０．１０Ｓｃ₂Ｏ₃−０．００５Ａｌ₂Ｏ₃）固体電解質基板１の片面にＮｉＯ−ＳＡＳＺのスラリ（１０ｍｏｌ％Ｓｃ₂Ｏ₃、０．５ｍｏｌ％Ａｌ₂Ｏ₃添加ジルコニア、ＮｉＯが６０ｗｔ％）を塗布しこの上に白金の集電メッシュ４を乗せて１３００℃、１時間焼成し燃料極３を設けた。
【００２４】
次にその裏面にＬＳＭ（Ｌａ_0.78Ｓｒ_0.2ＭｎＯ₃）のスラリを塗布し、１２００℃、１時間の条件で焼成し空気極２とした。燃料極３、空気極２ともに６ｍｍ径とした。この燃料電池セルをセル＃１−０−１とする。これを比較例とする。
【００２５】
次に、電極活性酸化物としてＣｅ_0.9Ｓｍ_0.1Ｏ_1.95，Ｃｅ_0.8Ｓｍ_0.2Ｏ_1.9，Ｃｅ_0.6Ｓｍ_0.4Ｏ_1.8，Ｃｅ_0.8Ｌａ_0.2Ｏ_1.9，Ｃｅ_0.8Ｇｄ_0.2Ｏ_1.9，Ｃｅ_0.8Ｌｕ_0.2Ｏ_1.9，Ｃｅ_0.8Ｙ_0.2Ｏ_1.9，Ｃｅ_0.8Ｇｄ_0.1Ｓｍ_0.1Ｏ_1.9の組成となる様に、電極活性酸化物材料の金属のアルコキシドを溶かしたトルエン溶液を調製した。
【００２６】
この溶液の金属の濃度は約４ｗｔ％とした。これをセル＃１−０−１と同じ条件で作製したセルの燃料極に含浸させた後、空気中、１１００℃で熱処理を行い所望の組成の電極活性酸化物を析出させた。これらをセル＃１−１−１〜＃１−１−８とする。
【００２７】
これらのセルおよび比較例のセルを用いて図２に示す燃料電池を組み立て、８００℃において発電試験を行った。ここで、燃料極には水素、空気極には酸素を供給した。開放起電力としては、１．１Ｖ以上の値が得られた。その結果を表１の＃１−０−１〜＃１−１−８に示す。＃１−１−１〜＃１−１−８は比較例であるセル＃１−０−１に比べて高いセル出力が得られた。
【００２８】
以上の様に本発明の製造方法により従来の方法に比べて優れた特性のセルを作製することに成功した。
【００２９】
【実施例２】
実施例１のセル＃１−０−１において電解質をＳＡＳＺに替えてＳＹｂＳＺ（０．８９ＺｒＯ₂−０．０９Ｓｃ₂Ｏ₃−０．０２Ｙｂ₂Ｏ₃）としたセルをセル＃２−０−１、さらに燃料極中のＮｉＯに替えてＮｉ_0.8Ｆｅ_0.2Ｏ_1.1を用いたセルをセル＃２−０−２、Ｎｉ_0.8Ｃｏ_0.2Ｏ_1.1を用いたセルをセル＃２−０−３、Ｎｉ_0.8Ｆｅ_0.1Ｃｏ_0.1Ｏ_1.1を用いたセルをセル＃２−０−４とする。
【００３０】
これらのセルを比較例のセルとする。そして、これらのセルに実施例１と同様にＣｅ_0.8Ｓｍ_0.2Ｏ_1.9の組成となるように電極活性酸化物材料のＣｅとＳｍのアルコキシド溶液を混合し、トルエン溶液としたものをセル＃２−０−１〜＃２−０−４の燃料極に含浸させ、１１００℃で熱処理を行った。これらのセルをセル＃２−１−１〜＃２−１−４とする。
【００３１】
これらのセル及び比較例のセルを用いて、実施例１と同様の実験を行った。この結果を表１のセル＃２−１−１〜＃２−１−４に示すが、いずれも比較例であるセル＃２−０−１〜＃２−０−４に比べ良好なセル出力特性が得られた。
【００３２】
【実施例３】
実施例２のセル＃２−０−１において含浸させる金属アルコキシド溶液を変更し、Ｌａ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃及びＬａ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｃｏ_0.10Ｏ₃、そしてＬａ_0.90Ｓｒ_0.10Ｇａ_0.71Ｍｇ_0.15Ｎｉ_0.07Ｃｏ_0.07Ｏ₃の組成となる様に溶液を調製して、燃料極に含浸させた。
【００３３】
そして、空気中、１０００℃で熱処理して所望の組成の電極活性酸化物を析出させた。これらをセル＃３−１−１〜＃３−１−３とする。これらのセルを用いて、実施例２と同様の実験を行った。この結果を表１のセル＃３−１−１〜＃３−１−３に示すが、いずれも比較例であるセル＃２−０−１に比べ良好なセル出力特性が得られた。
【００３４】
【実施例４】
ここでは、ＬＳＧＭ（Ｌａ_0.90Ｓｒ_0.10Ｇａ_0.85Ｍｇ_0.15Ｏ₃）を固体電解質とした。これはＬａ₂Ｏ₃，ＳｒＣＯ₃，Ｇａ₂Ｏ₃，ＭｇＯ粉末を所望の組成となる様に混合した後、１４００℃で空気中で固相反応を起こさせ合成した。合成した粉末をペレット状に成形し、１５００℃で焼成した。このペレットを研磨し、０．３ｍｍ厚、２４ｍｍ径の固体電解質とした。
【００３５】
次にＮｉＯとＬａ_0.90Ｓｒ_0.10Ｇａ_0.85Ｍｇ_0.15Ｏ₃微粒子との混合体のスラリを上記の固体電解質上に塗布し、１３００℃で焼成し燃料極とした。そして、燃料極の対面にＬＳＭ空気極を実施例１と同様の方法で設けた。
【００３６】
このセルをセル＃４−０−１とする。セル＃４−０−１に組成がＣｅ_0.8Ｓｍ_0.2Ｏ_1.9、Ｃｅ_0.8Ｇd_0.2Ｏ_1.9となる様に金属アルコキシド溶液を調製して燃料極に含浸させ、実施例１と同様に空気中１１００℃で熱分解反応を行い、電極活性酸化物であるＣｅ_0.8Ｓｍ_0.2Ｏ_1.9、Ｃｅ_0.8Ｇd_0.2Ｏ_1.9の微粒子を燃料極内に析出させた。
【００３７】
このセルをセル＃４−１−１、セル＃４−１−２とし、実施例１と同様の実験を行った。この結果を表１のセル＃４−１−１、セル＃４−１−２に示すが、比較例であるセル＃４−０−１に比べ良好なセル出力特性が得られた。
【００３８】
【実施例５】
実施例４のセル＃４−０−１と同じ種類のセルに、電極活性酸化物としてＬａ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃及びＬａ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｃｏ_0.10Ｏ₃、Ｌａ_0.90Ｓｒ_0.10Ｇａ_0.71Ｍｇ_0.15Ｎｉ_0.07Ｃｏ_0.07Ｏ₃、Ｐｒ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃、Ｓｍ_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃、Ｇd_0.90Ｓｒ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃、Ｌａ_0.90Ｃａ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃、Ｌａ_0.90Ｂａ_0.10Ｇａ_0.75Ｍｇ_0.15Ｎｉ_0.10Ｏ₃の組成となる様に金属アルコキシド溶液を調製して燃料極へ含浸させて実施例４と同様の実験を行った。
【００３９】
この結果を表１のセル＃５−１−１〜＃５−１−８に示す。いずれも比較例であるセル＃４−０−１に比べ良好なセル出力特性が得られた。
【００４０】
【実施例６】
実施例１の電解質に替えてＹＳＺ（０．９２ＺｒＯ₂−０．０８Ｙ₂Ｏ₃）の０．１ｍｍ厚のシートを用意し、この上にＮｉＯ−ＹＳＺ混合体を含むスラリ（ＮｉＯが６０ｗｔ％）を塗布し、１３００℃で焼成し燃料極とした。
【００４１】
次に０．９２（Ｚｒ_0.93Ｔｉ_0.07）Ｏ₂−０．０８Ｙ₂Ｏ₃の組成となるように金属アルコキシド溶液調製して、この燃料極に含浸させ１１００℃において熱処理を行い電極活性酸化物を析出させた。
【００４２】
次にこの上にＬＳＭ空気極を実施例１と同様の方法で設けた。このセルをセル＃６−１−１とする。ここで燃料極に上記の溶液を含浸させなかったセルを比較例として作製した。これをセル＃６−０−１とする。
【００４３】
これらのセルを用いて実施例１と同様の実験を行った。この結果を表１のセル＃６−０−１、＃６−１−１に示す。比較例であるセル＃６−０−１に比べセル＃６−１−１は良好な出力特性が得られた。
【００４４】
【実施例７】
実施例１の比較例であるセル＃１−０−１をここでも比較例として使用する。そして、このセルに電極活性酸化物としてＣｅ_0.9Ｓｍ_0.1Ｏ_1.95、Ｃｅ_0.8Ｓｍ_0.2Ｏ_1.9、Ｃｅ_0.6Ｓｍ_0.4Ｏ_1.8、Ｃｅ_0.8Ｌａ_0.2Ｏ_1.9、Ｃｅ_0.8Ｙ_0.2Ｏ_1.9の組成となる様にＣｅ，Ｓｍ，Ｌａ，Ｙのモル比を調製した硝酸塩水溶液を用意し、これをセル＃６−０−１と同じ種類のセルの燃料極へ含浸させた。
【００４５】
そして、空気中、１１００℃で熱処理を行い所望の組成の電極活性酸化物を析出させた。これらをセル＃７−１−１〜セル＃７−１−５とし、実施例５と同様の実験を行った。その結果を表１のセル＃７−１−１〜セル＃７−１−５に示す。これらは比較例であるセル＃１−０−１に比べて高いセル出力が得られた。
【００４６】
以上の様に本発明の製造方法により従来の方法に比べて優れた特性のセルを作製することに成功した。
【００４７】
【表１】

【００４８】
【表２】

【００４９】
【表３】

【００５０】
【表４】

【００５１】
【発明の効果】
以上説明したように、燃料極と固体電解質を焼成した後に混合導電体酸化物を構成するための金属元素を含む有機金属または無機金属塩の溶液を燃料極に含浸させ、その後熱分解反応によりこの酸化物を電解質との界面付近に形成した。これにより焼成過程にあまり制約を受けずに高性能な固体電解質型燃料電池用燃料極を得ることに成功した。本発明は固体燃料電池の高効率化に大きな貢献をなすものである。
【図面の簡単な説明】
【図１】実施例における単セルおよび燃料電池セルの構造を示す図。
【図２】実施例における燃料電池の構造を示す断面図。
【符号の説明】
１固体電解質
２空気極
３燃料極
４集電メッシュ
５白金端子
６ガスシール[0001]
[Industrial application fields]
The present invention relates to a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell.
[0002]
[Prior art and problems]
In recent years, there has been a growing interest in solid oxide fuel cells using oxygen ion conductors. In particular, from the viewpoint of effective use of energy, solid fuel cells are not subject to the restrictions of Carnot efficiency, so they have inherently high energy conversion efficiency and have excellent features such as better environmental conservation. .
[0003]
However, the manufacturing cost of the solid oxide fuel cell is high because the main part is made of ceramic. This hinders the spread of solid oxide fuel cells. Here, when the operating temperature of the battery is changed from the current 1000 ° C. to 800 ° C. or lower, metal can be used. Thereby, the interconnector part which occupies the main volume can be replaced with an inexpensive metal, which leads to a significant cost reduction.
[0004]
For the purpose of lowering the temperature, improvement of the ionic conductivity of the electrolyte, reduction of the thickness of the electrolyte, and the like have been studied. The solid electrolyte, rare-earth-doped zirconia _{((1-x) ZrO 2} -x A 2 O 3, A is La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu , Y, Sc, Al, Ga, etc., and 0.025 ≦ x ≦ 0.15) to make it thin, Sc-doped zirconia electrolyte material with high ion conductivity, or lanthanum gallate electrolyte _{_{_{Ln 1-x a x B 1}}} -y Mg y O 3 (Ln is La, Pr, Nd, with elements such as Sm a is Sr, Ca, Ba, etc., x is from 0.05 ≦ x ≦ 0.2, B Is mainly Ga, Al, etc., and the total amount y of Mg is 0.05 ≦ y ≦ 0.3). In addition to these, it is necessary to greatly improve the performance of electrodes such as fuel electrodes. This is because the electrochemical reaction rate rapidly decreases as the temperature is lowered.
[0005]
The fuel cell has an air electrode and a fuel electrode sandwiched between electrolytes. These electrodes supply gas and electrons to the electrolyte and provide a place for an electrochemical reaction at the interface with the electrolyte. Yes. This reaction field is called a three-phase interface because the gas, electrons, and ions are in contact.
[0006]
NiO-YSZ, ie, a mixture of Ni as an electron conductor and YSZ (0.92ZrO ₂ -0.08Y ₂ O ₃ ) as an oxygen conductor is used for the fuel electrode, and the three-phase interface is formed of Ni and YSZ. Can be at the interface. It is said that when the electrode active oxide, which is a conductor for both electrons and oxygen ions, is in contact with this interface, the reaction field, that is, the three-phase interface is remarkably expanded, and the electrode characteristics are improved.
[0007]
As an example of an electrode active oxide that is stable in a reducing atmosphere, Co at the B site of a ceria-based oxide such as SDC (Ce _0.8 Sm _0.2 O _1.9 ) and a lanthanum gallate-based oxide such as (LaSr) (GaMg) O ₃ A system to which transition metals such as Ni and Ni are added is known.
[0008]
The fuel electrode can also be sintered by using a raw material powder obtained by mixing these materials with NiO—YSZ, which is a conventional material. However, in the process of manufacturing the cell, it is exposed to a high temperature of about 1300 ° C., and these materials react with an electrolyte or an oxide such as NiO forming a fuel electrode to generate a deteriorated material near the interface.
[0009]
For example, in a zirconia-based electrolyte and a lanthanum-based perovskite oxide, La ₂ Zr ₂ O ₇ or SrZrO _{3 as} an insulator, and a ceria-based material and a zirconia electrolyte generate Ce _0.5 Zr _0.5 O ₂ having a very low oxygen ion conductivity. In addition, the lanthanum gallate mixed conductor and the lanthanum gallate solid electrolyte are easy to make a solid solution, diffuse deeply into the solid electrolyte, and may lower the ion transport number of the electrolyte. cause.
[0010]
In this way, the cell electrodes and electrolytes are required to suppress deterioration reaction even in a considerably high temperature range as compared to the operating temperature of 700 ° C. to 1000 ° C. Is difficult.
[0011]
[Object of the present invention]
The present invention is required for a method for producing a cell for a solid electrolyte. In order to improve the electrode characteristics of a fuel electrode, a method for producing a fuel electrode in which a mixed conductor is introduced in the vicinity of the interface with the electrolyte and no degradation product is produced. The purpose is to provide.
[0012]
[Means for solving problems]
In order to solve the above problems, the method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell according to the present invention comprises a dense solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof. In the method of introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell having a configured fuel cell, after the fuel electrode and the solid electrolyte are sintered and formed, the inside of the porous fuel electrode After impregnating an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution, an electrode active oxide having a desired composition is obtained as an electrolyte by a pyrolytic oxidation reaction. kind of a method of introducing into the vicinity of the interface consists of the solid electrolyte is a rare earth or Al, zirconia oxide doped with one or more selected from the group of Ga, the fuel electrode is a rare earth or Al, and Ga Zirconia oxide doped with upper and Ni or an alloy of Ni and Co or Fe or consists of a mixture of these oxides, the composition of the electrode active oxide Ce _{_1-x} Ln _x O _{2-x / 2} (Ln is Y or any of the periodic table of La to which Ce is excluded from Lu, or a system in which two or more of these elements are added, and the total amount x is 0.1 ≦ x ≦ 0.4) . Furthermore, the second method for introducing an electrode active oxide into the fuel electrode for a solid oxide fuel cell according to the present invention comprises a dense solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof. In the method of introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell having a fuel cell, after the fuel electrode and the solid electrolyte are formed by sintering, electron conduction is conducted inside the porous fuel electrode. And impregnating the electrode active oxide material having both oxygen ion conductivity in the form of an organic metal solution or an inorganic metal salt solution, and then subjecting the electrode active oxide having the desired composition to the vicinity of the electrolyte by a pyrolytic oxidation reaction. The solid electrolyte is made of a lanthanum gallate oxide, and the fuel electrode is made of a lanthanum gallate oxide and an alloy of Ni or Ni and Co or Fe, or these oxides. Consists of a mixture, the composition of the electrode active oxide _{_{_{Ce 1-x Ln x O 2}}} -x / 2 ( one Ln is other than Ce in the Lu from La Y or the periodic table, or A system in which two or more of these elements are added, and the total amount x is 0.1 ≦ x ≦ 0.4). Further, the third method for introducing an electrode active oxide into the fuel electrode for a solid oxide fuel cell according to the present invention comprises a dense solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof. In the method of introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell having a fuel cell, after the fuel electrode and the solid electrolyte are formed by sintering, electron conduction is conducted inside the porous fuel electrode. And impregnating the electrode active oxide material having both oxygen ion conductivity in the form of an organic metal solution or an inorganic metal salt solution, and then subjecting the electrode active oxide having the desired composition to the vicinity of the electrolyte by a pyrolytic oxidation reaction. The solid electrolyte is made of a zirconia-based oxide to which at least one selected from the group of rare earth and Al, Ga is added, and the fuel electrode is added with at least one of rare earth, Al, and Ga Zirconia-based oxide and Ni or an alloy of Ni and Co or Fe or consists of a mixture of these oxides, the composition of the electrode active oxide, (1-y) (Zr 1-x Ti _x O ₂ ) -y (Ln ₂ O ₃ ) (Ln is Y, Sc, or any of Gd to Lu in the periodic table, or two or more of these elements, and the total amount x of Ti is 0.03 ≦ x ≦ 0.2, and the total amount y of Ln ₂ O ₃ is 0.03 ≦ y ≦ 0.15). The fourth method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell according to the present invention is a fuel cell comprising a dense solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. In the method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell having a cell, after the fuel electrode and the solid electrolyte are sintered and formed, electron conduction and oxygen are introduced into the porous fuel electrode. After impregnating the electrode active oxide material that has both ionic conduction in the form of an organic metal solution or inorganic metal salt solution, the electrode active oxide of the desired composition is introduced near the interface with the electrolyte by pyrolysis oxidation reaction The solid electrolyte is made of a zirconia-based oxide to which at least one selected from the group of rare earths and Al, Ga is added, and the fuel electrode is a zirco to which at least one of rare earths, Al, and Ga is added. A system oxide and Ni or an alloy of Ni and Co or Fe or consists of a mixture of these oxides, the composition of the electrode active _{_{_{oxide, Ln 1-x C x Ga}}} 1-y D _y O ₃ (Ln is one or more elements of La, Pr, Nd, Eu , Gd, Tb, C is one or more elements of Ca, Sr, Ba, D is Mg, Ni, Co , Fe, Al, one or more elements, 0.05 ≦ x ≦ 0.2, 0.1 ≦ y ≦ 0.3). A fifth method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell according to the present invention comprises a dense solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. In the method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell having a cell, after the fuel electrode and the solid electrolyte are sintered and formed, electron conduction and oxygen are introduced into the porous fuel electrode. After impregnating the electrode active oxide material that has both ionic conduction in the form of an organic metal solution or inorganic metal salt solution, the electrode active oxide of the desired composition is introduced near the interface with the electrolyte by pyrolysis oxidation reaction The solid electrolyte is made of a lanthanum gallate oxide, and the fuel electrode is made of a lanthanum gallate oxide and an alloy of Ni or Ni and Co or Fe, or a mixture of these oxides. Is configured, the composition of the electrode active _{_{_{oxide, Ln 1-x C x Ga}}} 1-y D y O 3 (Ln is La, Pr, Nd, Eu, Gd, at least one element in the Tb , C is one or more elements in Ca, Sr, Ba, D is one or more elements in Mg, Ni, Co, Fe, Al, 0.05 ≦ x ≦ 0.2, 0.1 ≦ y ≦ 0.3).
[0013]
That is, according to the present invention, a solution for forming an electrode active oxide in the form of an organic metal solution or an inorganic metal salt solution in the fuel electrode after the firing of the fuel electrode and the solid electrolyte that is the highest temperature firing process is completed. Impregnate. Thereafter, a desired mixed conductor, that is, an electrode active oxide is introduced in the vicinity of the solid electrolyte interface by causing a pyrolytic oxidation reaction of the liquid in the fuel electrode at an appropriate temperature at which no deterioration reaction occurs.
[0014]
Here, as a method of manufacturing the cell, when the fuel electrode is first formed and the electrolyte and the air electrode are formed thereon, the solution is impregnated immediately after the electrolyte is manufactured or after the air electrode is manufactured. When the fuel electrode is formed last, it is impregnated after the fuel electrode is formed. When all the interconnectors and the like are integrally fired, they are impregnated after firing.
[0015]
[Action]
The operation of the present invention will be described below.
[0016]
In order to suppress deterioration at the interface, a zirconia solid electrolyte and a zirconia fuel electrode, or a lanthanum gallate solid electrolyte and a lanthanum gallate fuel electrode are used for the fuel electrode. Thereby, the firing of the fuel electrode and the solid electrolyte can be performed at a sufficiently high temperature, and a fuel electrode and a dense solid electrolyte with sufficiently high mechanical strength can be obtained.
[0017]
After finishing these firings, the fuel electrode is impregnated with an organic metal solution or an inorganic metal salt solution. Although the fuel electrode has fine pores although it is a porous body, it is difficult to sufficiently permeate the electrolyte interface with a slurry in which a normal powder is developed into a solution.
[0018]
However, since the solution used here does not contain solid matter, it penetrates the fuel electrode and reaches the vicinity of the interface between the electrolyte and the fuel electrode. This solution generates an electrode active oxide such as SDC by a thermal decomposition oxidation reaction.
[0019]
Here, the composition of the electrode active oxide can be easily controlled by previously controlling the amount of the metal element contained in the solution for forming the electrode active oxide. Since this electrode active oxide can conduct both electrons and oxygen ions, the three-phase interface contributing to the electrode reaction spreads throughout the electrode active oxide. For this reason, the electrode characteristics of the fuel electrode are greatly improved.
[0020]
By the above method, the electrode active electrode active oxide can be introduced into the fuel electrode without much restrictions on the firing temperature in the manufacturing process of the cell, and a fuel electrode for a high performance solid oxide fuel cell can be obtained. realizable.
[0021]
【Example】
Examples of the present invention will be described below. Of course, the present invention is not limited to the following examples.
[0022]
[Example 1]
The fuel cell used in the examples and the fuel cell assembled using the same are shown in FIGS. As is clear from FIGS. 1 and 2, an air electrode 2 is formed on one surface of the dense solid electrolyte 1, and a fuel electrode 3 is formed on the other surface. The air electrode 2 and the fuel electrode 3 are made of platinum. The current collector mesh 4 is provided. In the figure, 5 is a platinum terminal and 6 is a gas seal.
[0023]
First, a 0.2 mm-thick Sc ₂ O ₃ and Al ₂ O ₃ -added zirconia (SASZ or 0.895ZrO ₂ -0.10Sc ₂ O ₃ -0.005Al ₂ O ₃ ) solid electrolyte substrate 1 baked by the doctor blade method NiO-SASZ slurry (10 mol% Sc ₂ O ₃ , 0.5 mol% Al ₂ O ₃ added zirconia, NiO 60 wt%) was applied on one side of the substrate, and a platinum current collecting mesh 4 was placed thereon at 1300 ° C. The fuel electrode 3 was provided after firing for 1 hour.
[0024]
Next, a slurry of LSM (La _0.78 Sr _0.2 MnO ₃ ) was applied to the back surface, and fired at 1200 ° C. for 1 hour to form an air electrode 2. Both the fuel electrode 3 and the air electrode 2 have a diameter of 6 mm. This fuel cell is referred to as cell # 1-0-1. This is a comparative example.
[0025]
Next, Ce _0.9 Sm _0.1 O _1.95 , Ce _0.8 Sm _0.2 O _1.9 , Ce _0.6 Sm _0.4 O _1.8 , Ce _0.8 La _0.2 O _1.9 , Ce _0.8 Gd _0.2 O _1.9 , Ce _0.8 Lu _0.2 O _1.9 , A toluene solution in which the metal alkoxide of the electrode active oxide material was dissolved so as to have a composition of Ce _0.8 Y _0.2 O _1.9 and Ce _0.8 Gd _0.1 Sm _0.1 O _1.9 was prepared.
[0026]
The metal concentration of this solution was about 4 wt%. This was impregnated into a fuel electrode of a cell produced under the same conditions as in cell # 1-0-1, and then heat-treated at 1100 ° C. in air to deposit an electrode active oxide having a desired composition. These are designated as cells # 1-1-1 to # 1-1-8.
[0027]
A fuel cell shown in FIG. 2 was assembled using these cells and the cell of the comparative example, and a power generation test was performed at 800 ° C. Here, hydrogen was supplied to the fuel electrode and oxygen was supplied to the air electrode. As the open electromotive force, a value of 1.1 V or more was obtained. The results are shown in # 1-0-1 to # 1-1-8 in Table 1. In the case of # 1-1-1 to # 1-1-8, a higher cell output was obtained as compared with the cell # 1-0-1 which is a comparative example.
[0028]
As described above, the production method of the present invention succeeded in producing a cell having superior characteristics as compared with the conventional method.
[0029]
[Example 2]
The cell was SYbSZ by changing the electrolyte _{_{_{SASZ (0.89ZrO 2 -0.09Sc 2 O 3}}} -0.02Yb 2 O 3) in the cell # 1-0-1 of Example 1 Cell # 2-0-1 Further, instead of NiO in the fuel electrode, a cell using Ni _0.8 Fe _0.2 O _1.1 is a cell # 2-0-2, a cell using Ni _0.8 Co _0.2 O _1.1 is a cell # 2-0-3, Ni _0.8 A cell using Fe _0.1 Co _0.1 O _1.1 is designated as cell # 2-0-4.
[0030]
These cells are referred to as comparative example cells. These cells were mixed with an alkoxide solution of Ce and Sm of an electrode active oxide material so as to have a composition of Ce _0.8 Sm _0.2 O _{1.9 in} the same manner as in Example 1 to obtain a toluene solution. The fuel electrode of 0-1 to # 2-0-4 was impregnated and heat-treated at 1100 ° C. These cells are referred to as cells # 2-1-1 to # 2-1-4.
[0031]
Using these cells and the cell of the comparative example, the same experiment as in Example 1 was performed. The results are shown in cells # 2-1-1 to # 2-1-4 in Table 1, all of which are superior to the cells # 2-0-1 to # 2-0-4 which are comparative examples. Characteristics were obtained.
[0032]
[Example 3]
The metal alkoxide solution impregnated in cell # 2-0-1 of Example 2 was changed to include La _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ and La _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Co _0.10 O ₃ , and La _0.90 A solution was prepared so as to have a composition of Sr _0.10 Ga _0.71 Mg _0.15 Ni _0.07 Co _0.07 O ₃ and impregnated in the fuel electrode.
[0033]
And it heat-processed in air at 1000 degreeC and deposited the electrode active oxide of a desired composition. Let these be cells # 3-1-1 to # 3-1-3. Using these cells, the same experiment as in Example 2 was performed. The results are shown in cells # 3-1-1 to # 3-1-3 in Table 1. All of the cell output characteristics were better than those of cell # 2-0-1 as a comparative example.
[0034]
[Example 4]
Here, LSGM (La _0.90 Sr _0.10 Ga _0.85 Mg _0.15 O ₃ ) was used as the solid electrolyte. This was synthesized by mixing La ₂ O ₃ , SrCO ₃ , Ga ₂ O ₃ , and MgO powders so as to have a desired composition and then causing a solid phase reaction in air at 1400 ° C. The synthesized powder was formed into a pellet and fired at 1500 ° C. The pellet was polished to obtain a solid electrolyte having a thickness of 0.3 mm and a diameter of 24 mm.
[0035]
Next, a slurry of a mixture of NiO and La _0.90 Sr _0.10 Ga _0.85 Mg _0.15 O ₃ fine particles was applied onto the above solid electrolyte and fired at 1300 ° C. to obtain a fuel electrode. The LSM air electrode was provided on the opposite side of the fuel electrode in the same manner as in Example 1.
[0036]
This cell is designated as cell # 4-0-1. A metal alkoxide solution was prepared in the cell # 4-0-1 so that the composition would be Ce _0.8 Sm _0.2 O _1.9 and Ce _0.8 Gd _0.2 O _1.9 and impregnated in the fuel electrode. Then, thermal decomposition reaction was performed to deposit fine particles of Ce _0.8 Sm _0.2 O _1.9 and Ce _0.8 Gd _0.2 O _1.9 as electrode active oxides in the fuel electrode.
[0037]
This cell was designated as cell # 4-1-1 and cell # 4-1-2, and the same experiment as in Example 1 was performed. The results are shown in cell # 4-1-1 and cell # 4-1-2 in Table 1. Good cell output characteristics were obtained compared to cell # 4-0-1 as a comparative example.
[0038]
[Example 5]
La _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ and La _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Co _0.10 O ₃ , La as electrode active oxides in the same type of cell as the cell # 4-0-1 in Example 4. _0.90 Sr _0.10 Ga _0.71 Mg _0.15 Ni _0.07 Co _0.07 O ₃ , Pr _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ , Sm _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ , Gd _0.90 Sr _0.10 Ga _0.75 Mg _0.15 Ni _0.10 Example 4 A metal alkoxide solution was prepared so as to have a composition of O ₃ , La _0.90 Ca _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ , La _0.90 Ba _0.10 Ga _0.75 Mg _0.15 Ni _0.10 O ₃ and impregnated in the fuel electrode. The same experiment was conducted.
[0039]
The results are shown in cells # 5-1-1 to # 5-1-8 in Table 1. In any case, better cell output characteristics were obtained compared to cell # 4-0-1 as a comparative example.
[0040]
[Example 6]
A 0.1 mm thick sheet of YSZ (0.92ZrO ₂ -0.08Y ₂ O ₃ ) was prepared in place of the electrolyte of Example 1, and a slurry containing NiO—YSZ mixture (NiO 60 wt%) thereon. Was applied and fired at 1300 ° C. to obtain a fuel electrode.
[0041]
Next, a metal alkoxide solution is prepared so as to have a composition of 0.92 (Zr _0.93 Ti _0.07 ) O ₂ -0.08Y ₂ O ₃ , impregnated in this fuel electrode, and heat-treated at 1100 ° C. to form an electrode active oxide. Precipitated.
[0042]
Next, an LSM air electrode was provided thereon in the same manner as in Example 1. This cell is referred to as cell # 6-1-1. Here, a cell in which the fuel electrode was not impregnated with the above solution was produced as a comparative example. This is cell # 6-0-1.
[0043]
Experiments similar to those of Example 1 were performed using these cells. The results are shown in cells # 6-0-1 and # 6-1-1 in Table 1. Compared with cell # 6-0-1 which is a comparative example, cell # 6-1-1 has better output characteristics.
[0044]
[Example 7]
Cell # 1-0-1 which is a comparative example of Example 1 is used here as a comparative example. In this cell, the electrode active oxide has a composition of Ce _0.9 Sm _0.1 O _1.95 , Ce _0.8 Sm _0.2 O _1.9 , Ce _0.6 Sm _0.4 O _1.8 , Ce _0.8 La _0.2 O _1.9 , Ce _0.8 Y _0.2 O _1.9 . A nitrate aqueous solution prepared with a molar ratio of Ce, Sm, La, and Y was prepared, and this was impregnated into the fuel electrode of the same type of cell as cell # 6-0-1.
[0045]
And it heat-processed at 1100 degreeC in the air, and deposited the electrode active oxide of a desired composition. These were designated as Cell # 7-1-1 to Cell # 7-1-5, and the same experiment as in Example 5 was performed. The results are shown in cell # 7-1-1 to cell # 7-1-5 in Table 1. As compared with the cell # 1-0-1 which is a comparative example, a high cell output was obtained.
[0046]
As described above, the production method of the present invention succeeded in producing a cell having superior characteristics as compared with the conventional method.
[0047]
[Table 1]

[0048]
[Table 2]

[0049]
[Table 3]

[0050]
[Table 4]

[0051]
【The invention's effect】
As described above, after firing the fuel electrode and the solid electrolyte, the fuel electrode is impregnated with a solution of an organic metal or an inorganic metal salt containing a metal element for constituting the mixed conductor oxide, and then this is performed by a thermal decomposition reaction. An oxide was formed near the interface with the electrolyte. As a result, we succeeded in obtaining a high-performance fuel electrode for a solid oxide fuel cell without much restrictions on the firing process. The present invention greatly contributes to improving the efficiency of solid fuel cells.
[Brief description of the drawings]
FIG. 1 is a diagram showing the structure of a single cell and a fuel cell in an example.
FIG. 2 is a cross-sectional view showing the structure of a fuel cell in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid electrolyte 2 Air electrode 3 Fuel electrode 4 Current collection mesh 5 Platinum terminal 6 Gas seal

Claims

In a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell comprising a fuel cell comprising a dense solid electrolyte and a porous fuel electrode and an air electrode provided on both sides thereof After sintering the fuel electrode and the solid electrolyte, the porous active electrode is impregnated with an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution. And then introducing an electrode active oxide having a desired composition into the vicinity of the interface with the electrolyte by pyrolytic oxidation reaction , wherein the solid electrolyte is added with one or more selected from the group of rare earths, Al and Ga A mixture of a zirconia oxide in which the fuel electrode is added with one or more of rare earths, Al and Ga, and an alloy of Ni or Ni and Co or Fe, or an oxide thereof. In is configured, the composition of the electrode active oxide _{_{_{Ce 1-x Ln x O 2}}} -x / 2 (Ln is any other than Ce in the Lu from La Y or the periodic table, or their Introduction of an electrode active oxide into a fuel electrode for a solid oxide fuel cell, characterized in that a total amount x is 0.1 ≦ x ≦ 0.4) in which two or more elements are added Method.

In a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell comprising a fuel cell comprising a dense solid electrolyte and a porous fuel electrode and an air electrode provided on both sides thereof After sintering the fuel electrode and the solid electrolyte, the porous active electrode is impregnated with an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution. And then introducing an electrode active oxide having a desired composition into the vicinity of the interface with the electrolyte by a pyrolytic oxidation reaction, wherein the solid electrolyte is made of a lanthanum gallate oxide, and the fuel electrode is a lanthanum gallate oxide alloy oxide and Ni or Ni and Co or Fe or consists of a mixture of these oxides, the composition of the electrode active oxide _{_{_{Ce 1-x Ln x O 2}}} -x / 2 ( n is Y or a system in which Ce in Lu is removed from La in the periodic table, or a system in which two or more of these elements are added, and the total amount x is 0.1 ≦ x ≦ 0.4) A method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell , characterized in that :

In a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell comprising a fuel cell comprising a dense solid electrolyte and a porous fuel electrode and an air electrode provided on both sides thereof After sintering the fuel electrode and the solid electrolyte, the porous active electrode is impregnated with an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution. And then introducing an electrode active oxide having a desired composition into the vicinity of the interface with the electrolyte by pyrolytic oxidation reaction, wherein the solid electrolyte is added with one or more selected from the group of rare earth, Al, and Ga A mixture of a zirconia oxide in which the fuel electrode is added with one or more of rare earths, Al and Ga, and an alloy of Ni or Ni and Co or Fe, or an oxide thereof. In is configured, the composition of the electrode active _{_{oxide, (1-y) (Zr}} 1-x Ti x O 2) -y (Ln 2 O 3) (Ln is Y, and Sc or the periodic table Gd To Lu, or two or more of these elements, the total amount x of Ti is 0.03 ≦ x ≦ 0.2, and the total amount y of Ln ₂ O ₃ is 0.03 ≦ y ≦ 0.15), and a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell.

In a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell comprising a fuel cell comprising a dense solid electrolyte and a porous fuel electrode and an air electrode provided on both sides thereof After sintering the fuel electrode and the solid electrolyte, the porous active electrode is impregnated with an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution. And then introducing an electrode active oxide having a desired composition into the vicinity of the interface with the electrolyte by pyrolytic oxidation reaction, wherein the solid electrolyte is added with one or more selected from the group of rare earths, Al and Ga A mixture of a zirconia oxide in which the fuel electrode is added with one or more of rare earths, Al and Ga, and an alloy of Ni or Ni and Co or Fe, or an oxide thereof. In is configured, the composition of the electrode active _{_{_{oxide, Ln 1-x C x Ga}}} 1-y D y O 3 (Ln is La, Pr, Nd, Eu, Gd, of one or more of the Tb Element, C is one or more elements in Ca, Sr, Ba, D is one or more elements in Mg, Ni, Co, Fe, Al, 0.05 ≦ x ≦ 0.2, 0. 1 ≦ y ≦ 0.3) A method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell.

In a method for introducing an electrode active oxide into a fuel electrode for a solid oxide fuel cell of a fuel cell comprising a fuel cell comprising a dense solid electrolyte and a porous fuel electrode and an air electrode provided on both sides thereof After sintering the fuel electrode and the solid electrolyte, the porous active electrode is impregnated with an electrode active oxide material having both electron conduction and oxygen ion conduction in the form of an organic metal solution or an inorganic metal salt solution. And then introducing an electrode active oxide having a desired composition into the vicinity of the interface with the electrolyte by a pyrolytic oxidation reaction, wherein the solid electrolyte is made of a lanthanum gallate oxide, and the fuel electrode is a lanthanum gallate oxide It is composed of an oxide and Ni or an alloy of Ni and Co or Fe, or a mixture of these oxides, and the composition of the electrode active oxide is Ln _1-x C _x Ga _1-y D _y O ₃ (Ln is one or more elements of La, Pr, Nd, Eu, Gd, Tb, C is one or more elements of Ca, Sr, Ba, D is Mg, Ni, Co, Fe , One or more elements in Al, 0.05 ≦ x ≦ 0.2, 0.1 ≦ y ≦ 0.3), the electrode activity for the fuel electrode for a solid oxide fuel cell Method for introducing oxide.