JP3661676B2 - Solid oxide fuel cell - Google Patents

Description

表1に800℃で電流密度0.3Acm^-2における発電電位の結果を示す。同一電流密度においては発電電位が高いものほど出力性能に優れる固体電解質型燃料電池となる。表1に示すようにいずれも比較例１より発電電位が高いことがわかる。以上の結果から空気極と電解質の間に電極反応層を設けることが好ましいことが確認された。
【０１４２】
細孔径について
(実施例4)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は0.5μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1350℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４３】
(実施例5)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は5μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1400℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４４】
(実施例6)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は10μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1400℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４５】
(実施例7)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は0.2μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1350℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４６】
(実施例8)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は15μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1400℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４７】
(実施例9)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、原料の平均粒子径は0.5μmからなるものを用いて、空気極表面上にスラリーコート法で成膜した後、1400℃で焼結させたこと以外は実施例1と同様の方法とした。
【０１４８】
（発電試験）
実施例1、実施例4〜9で得られた電池（燃料極有効面積：150cm²）を用いて発電試験を行った。このときの運転条件は以下であった。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
さらに、発電試験後において、実施例1、実施例4〜9における電極反応層の細孔径を測定した。
【０１４９】
【表２】

表2に800℃で電流密度0.3Acm^-2における発電電位の結果を示す。同一の材料を用いているにも関わらず電極反応層の細孔径によって発電電位が異なっていることがわかる。実施例1、4〜6、9においては発電電位が高いが実施例7、8においては電位が低下していることがわかる。しかし、表1に示した比較例１よりは高いので特に問題はない。以上の結果から電極反応層の細孔径としては発電電位の高い値を呈している0.1〜10μm程度がより好ましいことが確認された。
【０１５０】
空隙率について
前記発電試験後において、実施例1、実施例4〜9における電極反応層の空隙率を測定した。
【０１５１】
【表３】

表3に800℃で電流密度0.3Acm^-2における発電電位の結果を示す。同一の材料を用いているにも関わらず電極反応層の空隙率によって発電電位が異なっていることがわかる。実施例1、4〜6、9においては発電電位が高いが実施例7、8においては電位が低下していることがわかる。実施例7、8においても電位低下はしているものの比較例1よりは高いので問題はない。以上の結果から電極反応層の空隙率としては発電電位の高い値を呈している3〜40％程度がより好ましいことが確認された。
【０１５２】
電極反応層の厚みについて
(実施例10)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが3μmであること以外は実施例1と同様にした。
【０１５３】
(実施例11)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが5μmであること以外は実施例1と同様にした。
【０１５４】
(実施例12)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが30μmであること以外は実施例1と同様にした。
【０１５５】
(実施例13)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが50μmであること以外は実施例1と同様にした。
【０１５６】
(実施例14)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが2μmであること以外は実施例1と同様にした。
【０１５７】
(実施例15)
電極反応層の組成としてはLa_0.75Sr_0.25MnO₃/ 90 mol％ZrO₂-10mol％Sc₂O₃=50/50とし、厚みが55μmであること以外は実施例1と同様にした。
【０１５８】
（発電試験）
実施例1、実施例10〜15で得られた電池（燃料極有効面積：150cm²）を用いて発電試験を行った。このときの運転条件は以下であった。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
【０１５９】
【表４】

表4は800℃で電流密度0.3Acm^-2における発電電位の結果を示す。同一の材料を用いているにも関わらず電極反応層の厚みによって発電電位が異なっていることがわかる。実施例1、10〜13においては発電電位が高いが実施例14、15においては電位が低下していることがわかる。実施例14、15においても電位低下はしているものの比較例1よりは高いので問題はない。以上の結果から電極反応層の厚みとしては発電電位の高い値を呈している3〜50μm程度が好ましいことが確認された。さらに、実施例1、10〜13で比較をすると実施例1、11,12が出力性能がより高いことから、電極反応層の厚みとしては5〜30μmであるとより好ましいことが確認された。
【０１６０】
電極反応層材料について
(実施例16)
電極反応層の材料をセリウム酸化物とし、該組成を(CeO₂)_0.8(Sm₂O₃)_{0. １}としたこと以外は実施例１と同様にした。
【０１６１】
(実施例17)
電極反応層の材料をSSZ/セリウム酸化物とし、該組成を90 mol％ZrO₂-10mol％Sc₂O₃/(CeO₂)_0.8(Sm₂O₃)_{0. １}=50/50とした以外は実施例1と同様にした。
【０１６２】
(実施例18)
電極反応層材料は、ランタンマンガナイト/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/(CeO₂)_0.8(Sm₂O₃)_{0. １}=50/50とした以外は実施例1と同様にした。
【０１６３】
(実施例19)
電極反応層材料は、ランタンマンガナイト/SSZ/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/90mol％ZrO₂-10mol％Sc₂O₃ /(CeO₂)_0.8(Sm₂O₃)_{0. １}=50/25/25とした。原料合成法としてはLa_0.75Sr_0.25MnO₃/90mol％ZrO₂-10mol％Sc₂O₃とLa_0.75Sr_0.25MnO₃/(CeO₂)_0.8(Sm₂O₃)_{0. １}を各々共沈法で作製した粉末をさらに、La_0.75Sr_0.25MnO₃/90mol％ZrO₂-10mol％Sc₂O₃ /(CeO₂)_0.8(Sm₂O₃)_{0. １}=50/25/25になるように混合し熱処理をした。これら以外は実施例1と同様にした。
【０１６４】
(実施例20)
電極反応層材料は、YSZとし、該組成を92mol％ZrO₂-8mol％Y₂O₃とした以外は実施例1と同様にした。
【０１６５】
(実施例21)
電極反応層材料は、ランタンマンガナイト/YSZとし、該組成をLa_0.75Sr_0.25MnO₃/92mol％ZrO₂-8mol％Y₂O₃=50/50とした以外は実施例1と同様にした。
【０１６６】
（発電試験）
実施例1、2、16〜21および比較例1の試験電池（燃料極有効面積：１５０cm²）を用いて以下に示す発電試験を行った。このときの運転条件は以下であった。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：７００〜１０００℃
▲４▼電流密度：０．３Acm^-2
【０１６７】
図３に発電温度における発電電位の結果を示す。実施例1、18、19においては700〜1000℃において高い電位を呈しているのがわかる。実施例2、16、17においては実施例1、18、19よりは劣るものの700℃まで比較的高い電位を呈していることがわかる。実施例20、21では900〜1000℃においては高い電位を呈しているが、900℃以下になると電位低下が大きくなっているのがわかる。これに対し、比較例1では1000℃においても実施例より低く、発電温度が低下するにつれさらに電位低下が大きくなっていることがわかる。以上の結果からいずれも比較例1と比較して発電電位が高く好ましいことが確認された。電極反応層がYSZおよびランタンマンガナイト/YSZの場合は900〜1000℃において高い出力性能を有し、電極反応層がSSZ、セリウム酸化物、およびSSZ/セリウム酸化物の場合は900℃以下においても高い出力性能を有し、好ましいことがわかった。さらに、電極反応層がランタンマンガナイト/SSZ,ランタンマンガナイト/セリウム酸化物およびランタンマンガナイト/SSZ/セリウム酸化物の場合、700℃程度においても出力性能に優れ、より好ましいことが確認された。
【０１６８】
電極反応層におけるスカンジアの固溶量について
(実施例22)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/ 97 mol％ZrO₂-3mol％Sc₂O₃=50/50にした以外は実施例1と同様にした。
【０１６９】
(実施例23)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/ 92 mol％ZrO₂-8mol％Sc₂O₃=50/50にした以外は実施例1と同様にした。
【０１７０】
(実施例24)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/ 88 mol％ZrO₂-12mol％Sc₂O₃=50/50にした以外は実施例1と同様にした。
【０１７１】
(実施例25)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/ 98 mol％ZrO₂-2mol％Sc₂O₃=50/50にした以外は実施例1と同様にした。
【０１７２】
(実施例26)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/ 85 mol％ZrO₂-15mol％Sc₂O₃=50/50にした以外は実施例1と同様にした。
【０１７３】
実施例1、実施例22〜26の電池について、以下に示す発電条件で発電試験を行った。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
【０１７４】
【表５】

【０１７５】
表5は800℃で電流密度0.3Acm^-2における発電電位の結果を示す。実施例1、実施例22〜24は高い電位であるのに対し、実施例25、26においては電位低下が起こっているのがわかる。しかし、実施例25、26においても表1に示す比較例1と比べるとはるかに高い電位を呈していることからこの程度の低下であれば問題ないことがわかった。電位が高いということから電極反応層のSSZにおけるスカンジアの固溶量は3〜12mol％の範囲が好ましいことが確認された。また、実施例1、実施例22〜24のデータを比較すると実施例22の電位が他と比較して低くなっていることからスカンジアの固溶量が8〜12mol％であるとより好ましいことが確認できた。
【０１７６】
SSZにおけるCeO₂等の効果
(実施例27)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/88mol％ZrO₂-10mol％Sc₂O₃-2mol％CeO₂ =50/50にした以外は実施例1と同様にした。
【０１７７】
(実施例28)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/85mol％ZrO₂-10mol％Sc₂O₃-5mol％CeO₂ =50/50にした以外は実施例1と同様にした。
【０１７８】
(実施例29)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/84mol％ZrO₂-10mol％Sc₂O₃-6mol％CeO₂ =50/50にした以外は実施例1と同様にした。
【０１７９】
(実施例30)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/88mol％ZrO₂-10mol％Sc₂O₃-2mol％Bi₂O₃ =50/50にした以外は実施例1と同様にした。
【０１８０】
(実施例31)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/88mol％ZrO₂-10mol％Sc₂O₃-2mol％Y₂O₃ =50/50にした以外は実施例1と同様にした。
【０１８１】
(実施例32)
電極反応層の組成およびその重量比率をLa_0.75Sr_0.25MnO₃/88mol％ZrO₂-10mol％Sc₂O₃-1mol％Y CeO₂-1mol％Bi₂O₃ =50/50にした以外は実施例1と同様にした。
【０１８２】
実施例1、実施例27〜32の電池について、以下に示す発電条件で発電試験を行った。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
【０１８３】
【表６】

表6は800℃で電流密度0.3Acm^-2における発電電位の結果を示す。実施例1、実施例27〜29を比較すると実施例27、実施例28は電位が高くなったが実施例29ではむしろ低くなる傾向が見られた。実施例30、実施例31については実施例1と電位としては変わっていないが電極反応層材料の焼結性が向上することが確認された。実施例32では電位が高くなることと電極反応層材料の焼結性が向上することが確認された。以上の結果から、SSZにCeO₂を5mol％以下固溶させると出力性能が向上することが確認され、好ましいことがわかった。また、Y₂O₃やBi₂O₃を固溶させると焼結性が向上することがわかり、好ましいことがわかった。Gd₂O₃,Yb₂O₃等の他の希土類酸化物を5mol％以下固溶させた場合においても出力性能の向上か焼結性の向上のいずれかの効果があることが容易に推測することができるので好ましいと考えられた。
【０１８４】
(CeO₂)_1-2x(Sm₂O₃)_xについて
(実施例33)
電極反応層材料は、ランタンマンガナイト/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/ (CeO₂)_0.9(Sm₂O₃)_0.05=50/50とした以外は実施例1と同様にした。
【０１８５】
(実施例34)
電極反応層材料は、ランタンマンガナイト/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/ (CeO₂)_0.7(Sm₂O₃)_0.15=50/50とした以外は実施例1と同様にした。
【０１８６】
(実施例35)
電極反応層材料は、ランタンマンガナイト/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/ (CeO₂)_0.75(Sm₂O₃)_0.025=50/50とした以外は実施例1と同様にした。
【０１８７】
(実施例36)
電極反応層材料は、ランタンマンガナイト/セリウム酸化物とし、該組成をLa_0.75Sr_0.25MnO₃/ (CeO₂)_0.65(Sm₂O₃)_0.175=50/50とした以外は実施例1と同様にした。
【０１８８】
実施例18、実施例33〜36の電池について、以下に示す発電条件で発電試験を行った。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
【０１８９】
【表７】

表7は800℃で電流密度0.3Acm^-2における発電電位の結果を示す。実施例18、実施例33〜36を比較すると実施例35、実施例36のx値になると幾分電位が低くなっていることがわかる。以上の結果から(CeO₂)_1-2x(Sm₂O₃)_xについては0.05≦x≦0.15の範囲がより好ましいことが確認された。なお、本実施例ではSmのみであるが、GdおよびYについても同様の効果があることを容易に推測することができるので好ましいと考えられた。
【０１９０】
電極反応層におけるランタンマンガナイトの組成について
(実施例37)
電極反応層の組成およびその重量比率をLa_0.75Ca_0.25MnO₃/90mol％ZrO₂-10mol％Sc₂O₃ =50/50にした以外は実施例1と同様にした。
【０１９１】
実施例1、実施例37の電池について、以下に示す発電条件で発電試験を行った。▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：800℃
▲４▼電流密度：0.3Acm^-2
【０１９２】
【表８】

表8は800℃で電流密度0.3Acm^-2における発電電位の結果を示す。実施例1と実施例31ではほとんど電位が変わらないことから電極反応層におけるランタンマンガナイトはCaまたはSrを固溶させたランタンマンガナイトのいずれであっても良いことが確認された。
【０１９３】
電解質材料について
(実施例38)
電解質材料はYSZで、該組成は、92 mol％ZrO₂-8mol％Y₂O₃であること以外は実施例1と同様とした。
【０１９４】
実施例1、38、比較例1の試験電池（燃料極有効面積：１５０cm²）を用いて以下に示す発電試験を行った。このときの運転条件は以下であった。
▲１▼燃料：(H₂+１１％H₂O)：N₂ ＝ １：２
▲２▼酸化剤：Ａｉｒ
▲３▼発電温度：７００〜１０００℃
▲４▼電流密度：０．３Acm^-2
【０１９５】
図4に発電温度における発電電位の結果を示す。実施例38は1000℃においてはほぼ同じ電位となるが、900℃以下になると電位低下が見られ700℃程度では実施例1とかなり電位差が大きくなっていることがわかる。しかし、比較例1とは大差がついていることがわかる。以上の結果から、900℃以下の発電温度においては電解質はSSZの方が好ましいが900℃以上ではほぼ同程度であることが確認され、電解質がYSZであっても問題ないことが確認された。
【０１９６】
実施例1および実施例19および実施例27に示す電極反応層を介在させることによって700℃程度の低温においても0.6V以上の高電位を有する固体電解質型燃料電池を提供することができた。
【０１９７】
【発明の効果】
以上の説明から明らかなように、空気極と電解質の間に少なくとも酸素ガスをイオン化する触媒を含み、連通した開気孔を有する電極反応層を設けることによって、出力性能に優れる固体電解質型燃料電池を提供することができる。
【図面の簡単な説明】
【図１】円筒タイプの固体電解質型燃料電池の断面を示す図である。
【図２】図１に示す固体電解質型燃料電池の空気極、電解質および燃料極構成について詳細に示した断面図である。
【図３】発電温度(横軸)と試験電池の発電電位（縦軸）の関係を示すグラフである。
【図４】発電温度(横軸)と試験電池の発電電位（縦軸）の関係を示すグラフである。
【符号の説明】
１：空気極支持体
２：インターコネクター
３：電解質
４：燃料極
５：電極反応層
６：燃料側電極反応層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid oxide fuel cell excellent in output performance. In particular, the present invention relates to a solid oxide fuel cell having excellent output performance even at an operating temperature of 700 to 900 ° C.
[0002]
[Prior art]
A conventional solid electrolyte fuel cell uses lanthanum manganite in which Sr or Ca is dissolved as an air electrode material, and zirconia (hereinafter referred to as YSZ) in which yttria is dissolved as an electrolyte material. A battery directly laminated with electrolyte was used. (For example, see Non-Patent Document 1.) Also, a thin layer of zirconia in which yttria is dissolved between the electrolyte and the air electrode can be provided to reduce the contact resistance between the air electrode and the electrolyte. There are some that can be improved. (For example, patent document 1). Furthermore, a layer made of a mixed powder of lanthanum manganite in which Ca and / or Sr is dissolved and zirconia in which yttria is dissolved is provided between the air electrode and the electrolyte to reduce the contact resistance between the air electrode and the electrolyte. Some of them are capable of improving the output performance. (For example, refer to Patent Document 2).
[0003]
[Non-Patent Document 1]
Kazuo Fueki and Masao Takahashi [Fuel Cell Design Technology] Science Forum Publishing, September 30, 1987, P221-230
[Patent Document 1]
Japanese Patent Laid-Open No. 8-180886 (page 1-4, Fig. 1)
[Patent Document 2]
JP 2000-44245 A (page 1-6)
[0004]
[Problems to be solved by the invention]
In the structure in which lanthanum manganite in which Sr or Ca is dissolved and YSZ that does not have gas permeability are laminated, the reaction of the formula (1) that occurs between the air electrode and the electrolyte occurs when the electrolyte surface and the air electrode are in contact with each other. There was a problem that the output performance was low due to the reaction only in that point. O₂+ 4e^-→ 2O^2-                                                … (1)
[0005]
If the method of patent document 1 and patent document 2 is employ | adopted, if the operating temperature is about 900-1000 degreeC, the output performance of a battery will improve by providing these layers. However, when the operating temperature is lowered to about 700 ° C., the electrode activity of these materials themselves is greatly reduced, and the output performance of the cell is greatly reduced as compared with the case of 900 to 1000 ° C.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a solid electrolyte fuel cell that improves electrode activity between an air electrode and an electrolyte and is excellent in output performance.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the first invention provides:A solid electrolyte fuel cell comprising an air electrode, an electrolyte, and a fuel electrode, and an electrode reaction layer interposed between the air electrode and the electrolyte, wherein the electrode reaction layer ionizes at least oxygen gas The electrode reaction layer is a layer in which lanthanum manganite and zirconia in which scandia is dissolved is uniformly mixed at a predetermined weight ratio, lanthanum manganite and cerium oxide. Any one of the group consisting of a layer in which lanthanum manganite and scandia are dissolved in a uniform weight ratio, and a layer in which zirconia and cerium oxide are uniformly mixed in a predetermined weight ratio. It was set as the structure which is a body. As a result, a power generation potential of 0.6 V or more is obtained even at 700 ° C., and a stable power generation capability can be exhibited even at low temperatures.
[0008]
  According to a second aspect of the present invention, there is provided a solid oxide fuel cell comprising an air electrode, an electrolyte, and a fuel electrode, wherein an electrode reaction layer is interposed between the air electrode and the electrolyte. The reaction layer includes at least a catalyst that ionizes oxygen gas, has open pores that communicate with each other, and the electrode reaction layer is a layer in which lanthanum manganite and zirconia in which scandia is dissolved are uniformly mixed at a predetermined weight ratio. A layer in which lanthanum manganite and cerium oxide are uniformly mixed in a predetermined weight ratio, and a layer in which lanthanum manganite and zirconia in which scandia is dissolved and cerium oxide are uniformly mixed in a predetermined weight ratio. It is a mixture of any one of the groups, and the electrolyte is zirconia in which yttria or scandia is dissolved. As a result, a solid oxide fuel cell having a power generation potential of 0.6 V or higher even at 700 ° C. and capable of obtaining high output performance even at a low temperature can be provided.
[0009]
This is because the electrode reaction layer has a function of promoting ionization of oxygen gas, so that the reaction of the formula (1) occurring between the air electrode and the electrolyte can be advanced efficiently, and the output performance can be improved. This is because it has open pores that communicate with each other, so that oxygen gas can be diffused throughout the electrode reaction layer, and the reaction of formula (1) can occur in the entire electrode reaction layer.
[0010]
In order to achieve the above object, the second invention provides that the pore diameter of the electrode reaction layer is 0.1 to 10 μm.
[0011]
According to the present invention, since the pore diameter in the electrode reaction layer is limited, the reaction of the formula (1) can be advanced efficiently, and a solid oxide fuel cell excellent in output performance can be provided.
[0012]
The reason is that if the pore diameter is smaller than 0.1 μm, there are almost no open pores in the electrode reaction layer, so that oxygen gas cannot be diffused into the electrode reaction layer and the output performance is reduced. This is because the contact point between the electrolyte and the electrode reaction layer is reduced when the thickness is larger than 10 μm, so that the adhesion is lowered, the contact resistance between the electrolyte and the electrode reaction layer is increased, and the output performance is lowered.
[0013]
The pore diameter shown here is determined by the following method. Take a cross-sectional photo of the electrode reaction layer polished with SEM and copy it onto a transparent film. The size of the void portion is measured. For example, when the void is equivalent to a circle, the diameter is the pore diameter, and when the void is square, the length of one side is calculated as the pore diameter.
[0014]
The pore diameter shown here is 0.1 to 10 μm, and 100 pore diameters were measured by the above method and measured in the 3rd to 97th range when arranged in order from the smallest diameter. It corresponds to the pore diameter. That is, the pore diameter in the range of 3% diameter to 97% diameter and corresponding to 50% diameter is 0.1 to 10 μm.
[0015]
In order to achieve the above object, the third invention provides that the pore diameter of the electrode reaction layer is smaller than the pore diameter of the air electrode.
[0016]
According to the present invention, since the relationship between the pore size of the electrode reaction layer and the air electrode is limited, a solid oxide fuel cell excellent in output performance can be provided.
[0017]
This is because the pore diameter of the electrode reaction layer is smaller than the pore diameter of the air electrode, so that the adhesion with the electrolyte is improved and the output performance is improved compared to the case where the air electrode and the electrolyte are laminated. is there.
[0018]
In order to achieve the above object, the fourth invention provides that the porosity of the electrode reaction layer is 3 to 40%.
[0019]
According to the present invention, since the porosity of the electrode reaction layer is limited, the reaction of formula (1) can be advanced efficiently, and a solid oxide fuel cell excellent in output performance can be provided.
[0020]
The reason for this is that if the porosity is less than 3%, there are too few open pores in the electrode reaction layer, so that oxygen gas cannot diffuse efficiently in the electrode reaction layer and the output performance is reduced. If it is larger than 40%, the contact between the electrolyte and the electrode reaction layer is reduced, so that the adhesion is lowered, the contact resistance between the electrolyte and the electrode reaction layer is increased, and the output performance is lowered.
[0021]
The porosity shown here is determined by the following method. A cross-sectional photograph of the electrode reaction layer portion polished by SEM is taken, and the void portion and the particle portion are color-coded and traced on a transparent film. The color-coded film is subjected to image processing to calculate the void ratio.
[0022]
In order to achieve the above object, the fifth invention provides that the porosity of the electrode reaction layer is not more than the porosity of the air electrode.
[0023]
According to the present invention, since the relationship between the porosity of the electrode reaction layer and the air electrode is limited, a solid oxide fuel cell excellent in output performance can be provided.
[0024]
This is because the porosity of the electrode reaction layer is equal to or less than the porosity of the air electrode, so that the adhesion with the electrolyte is improved and the output performance is improved as compared with the case where the air electrode and the electrolyte are laminated.
[0025]
In order to achieve the above object, the sixth invention provides that the thickness of the electrode reaction layer is 3 to 50 μm.
[0026]
According to the present invention, since the thickness of the electrode reaction layer is limited, the reaction of the formula (1) can be efficiently advanced, and a solid oxide fuel cell excellent in output performance can be provided.
[0027]
The reason for this is that if the thickness of the electrode reaction layer is smaller than 3 μm, the reaction field capable of performing the reaction of formula (1) decreases, so that the output performance is reduced. This is because the output performance deteriorates because it cannot be diffused efficiently.
[0028]
In order to achieve the above object, the seventh invention provides that the thickness of the electrode reaction layer is 5 to 30 μm.
[0029]
According to the present invention, since the thickness of the electrode reaction layer is further limited, the reaction of the formula (1) can be further efficiently advanced, and a solid oxide fuel cell excellent in output performance can be provided.
[0030]
The reason for this is that when the thickness of the electrode reaction layer is in the range of 5 to 30 μm, there are many reaction fields capable of performing the reaction of formula (1), and oxygen gas can be efficiently diffused into the electrode reaction layer. is there.
[0031]
In order to achieve the above object, the eighth invention provides that the thickness of the electrode reaction layer is smaller than the thickness of the air electrode.
[0032]
According to the present invention, since the relationship between the electrode reaction layer and the thickness of the air electrode is limited, it is possible to provide a solid oxide fuel cell having excellent output performance.
[0033]
This is because if the electrode reaction layer is thicker than the air electrode, the reaction of the formula (1) cannot be advanced efficiently.
[0034]
In order to achieve the above object, the ninth invention provides a zirconia layer (hereinafter referred to as SSZ) in which an electrode reaction layer is a solution of scandia, a cerium oxide layer, zirconia and a cerium oxide in which scandia is dissolved. Is any one member of the group consisting of layers uniformly mixed in a predetermined weight ratio (hereinafter referred to as SSZ / cerium oxide).
[0035]
According to the present invention, since the electrode reaction layer is any one of SSZ, cerium oxide, and SSZ / cerium oxide, a solid oxide fuel cell having excellent output performance even at 900 ° C. or lower can be provided.
[0036]
This is because SSZ, cerium oxide, and SSZ / cerium oxide are higher than the oxygen ion conductivity of YSZ conventionally used for the electrode reaction layer.
[0037]
In order to achieve the above object, according to a tenth invention, the electrode reaction layer further has an electronic conductivity of 10 Scm at 1000 ° C.^-1It provides that the material which becomes the above is contained.
[0038]
According to the present invention, since the electrode reaction layer contains a material having higher electronic conductivity, the reaction of the formula (1) can be efficiently advanced, and a solid oxide fuel cell excellent in output performance is provided. be able to.
[0039]
This is because the reaction shown in the formula (1) can be promoted because the electrode reaction layer contains a material having high electronic conductivity. Electronic conductivity is 10Scm^-1This is because IR loss occurs in the electrode reaction layer when only a smaller material is used, and the reaction efficiency of the equation (1) is lowered.
[0040]
In order to achieve the above object, according to an eleventh invention, the electrode reaction layer is a layer in which lanthanum manganite and zirconia in which scandia is dissolved is uniformly mixed at a predetermined weight ratio (hereinafter referred to as lanthanum manganite / SSZ). A layer in which lanthanum manganite and cerium oxide are uniformly mixed at a predetermined weight ratio (hereinafter referred to as lanthanum manganite / cerium oxide), zirconia in which lanthanum manganite and scandia are dissolved, and Provided is a mixture of any one of the group consisting of layers (hereinafter referred to as lanthanum manganite / SSZ / cerium oxide) in which cerium oxide is uniformly mixed at a predetermined weight ratio.
[0041]
According to the present invention, since a mixture of lanthanum manganite having a high electron conductivity and SSZ and / or cerium oxide having a high oxygen ion conductivity was selected as the electrode reaction layer, at a power generation temperature of about 700 to 900 ° C. In addition, a solid oxide fuel cell having excellent output performance can be provided.
[0042]
The reason for this is that lanthanum manganite with high electronic conductivity is included, so that the reaction of formula (1) can be promoted, and SSZ, cerium oxide, which has high oxygen ion conductivity even at a low temperature of about 700 ° C. This is because the generated oxygen ions can be efficiently transported to the electrolyte because SSZ / cerium oxide is contained.
[0043]
In order to achieve the above object, the twelfth invention provides that the amount of scandia dissolved in SSZ in the electrode reaction layer is 3 to 12 mol%.
[0044]
According to the present invention, since the solid solution ratio of SSZ is limited, it is possible to provide a solid oxide fuel cell excellent in output performance even at a power generation temperature of about 700 to 900 ° C.
[0045]
The reason why the scandia solid solution amount is preferably 3 to 12 mol% is that the crystal phase in this range is stable and the oxygen ion conductivity is high. From the viewpoint of high oxygen ion conductivity, it is more preferable that the solid solution is 8 to 12 mol%.
[0046]
In addition, the range other than the range of 3 to 12 mol% is not preferable because the oxygen ion conductivity is low at less than 3 mol%, and the output performance is lowered at a low power generation temperature, while the crystal phase is cubic when it exceeds 12 mol%. This is because the rhombohedral crystal phase precipitates and the oxygen ion conductivity decreases.
[0047]
In order to achieve the above object, the thirteenth invention is characterized in that the SSZ in the electrode reaction layer further includes CeO.₂, Gd₂O_Three, Y₂O_Three, Yb₂O_ThreeRare earth oxide and Bi₂O_Three1 or 2 or more types of oxides are solid-dissolved, and the oxide is provided as a solid solution of 5 mol% or less in total.
[0048]
According to the present invention CeO₂, Gd₂O_Three, Y₂O_3,Yb₂O_ThreeRare earth oxide and Bi₂O_ThreeThus, a solid oxide fuel cell having excellent output performance even at a power generation temperature of about 700 to 900 ° C. can be provided.
[0049]
The content of 5 mol% or less is preferable because the oxygen ion conductivity is increased, the sinterability of the material is improved, or at least one of the effects is produced. That is, if the oxygen ion conductivity is improved, the output performance is improved, and if the sinterability is improved, low-temperature sintering is possible. Those in which two or more kinds are dissolved are preferable because there is a possibility that both oxygen ion conductivity and sinterability can be obtained. On the other hand, if it is contained in an amount of more than 5 mol%, a rhombohedral phase is deposited as a crystal layer in addition to cubic crystals, and oxygen ion conductivity is lowered.
[0050]
To achieve the above object, according to a fourteenth aspect of the present invention, there is provided a lanthanum manganite in an electrode reaction layer comprising LaAM_ThreeProvided that it is a lanthanum manganite represented by (where A = Ca or Sr).
[0051]
According to the present invention, the electrode reaction layer is made of LaAMnO._ThreeSince the lanthanum manganite represented by (A = Ca or Sr) is provided, a solid oxide fuel cell having high electronic conductivity and excellent output performance even at a power generation temperature of 700 to 900 ° C. is provided. be able to.
[0052]
This is because the electronic conductivity is high and the material is stable in an air atmosphere of 700 ° C. or higher.
[0053]
In order to achieve the above object, the fifteenth invention is the cerium oxide in the electrode reaction layer represented by the general formula (CeO₂)_1-2X(B₂O_Three)_X(Where B = Sm, Gd, Y, 0.05 ≦ X ≦ 0.15).
[0054]
According to the present invention, since the composition of the cerium oxide is limited, it is possible to provide a solid oxide fuel cell excellent in output performance even at a power generation temperature of about 700 to 900 ° C.
[0055]
This is because the general formula (CeO₂)_1-2X(B₂O_Three)_X(However, any one of B = Sm, Gd, and Y, 0.05 ≦ X ≦ 0.15) has a high oxygen ion conductivity and allows the reaction of formula (1) to proceed efficiently even at about 700 ° C. It is because it can do.
[0056]
In order to achieve the above object, the sixteenth invention provides that the electrolyte is YSZ or SSZ.
[0057]
According to the present invention, since the electrolyte material is YSZ or SSZ, a solid oxide fuel cell capable of obtaining high output performance even at 700 to 900 ° C. can be provided.
[0058]
This is because YSZ and SSZ have high oxygen ion conductivity and are stable as materials. From the viewpoint of high oxygen ion conductivity, yttria in which an appropriate amount is dissolved and zirconia in which scandia is dissolved are preferable.
[0059]
In order to achieve the above object, the seventeenth invention is the air electrode, LaAMnO_ThreeIt is provided that it is a lanthanum manganite represented by (where A = Ca or Sr).
[0060]
According to the present invention, since the composition in the air electrode is limited, it is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature of 700 to 900 ° C.
[0061]
This is because the electronic conductivity is high and the material is stable in an air atmosphere of 700 ° C. or higher.
[0062]
In order to achieve the above object, according to an eighteenth aspect of the invention, the fuel electrode comprises a layer (hereinafter referred to as NiO / YSZ) in which NiO and zirconia in which yttria is dissolved are uniformly mixed at a predetermined weight ratio. Offering to be.
[0063]
According to the present invention, since the fuel electrode is NiO / YSZ, it is possible to provide a solid oxide fuel cell having excellent output performance.
[0064]
The reason for this is that since Ni is contained, the electron conductivity is high, and since YSZ is mixed, the aggregation of Ni can be suppressed and the durability is excellent. NiO / YSZ shown here indicates a layer in which NiO and YSZ are uniformly mixed at a predetermined weight ratio.
[0065]
In order to achieve the above object, according to a nineteenth aspect of the present invention, there is provided a layer in which zirconia in which NiO and scandia are dissolved is uniformly mixed between a fuel electrode and an electrolyte at a predetermined weight ratio (hereinafter referred to as NiO / The fuel side electrode reaction consisting of SSZ) is interposed.
[0066]
According to the present invention, since a layer in which SSZ, which has higher oxygen ion conductivity than YSZ, is mixed with NiO is provided on the electrolyte side, a solid oxide fuel cell having excellent output performance even at an operating temperature of 700 ° C. can be provided.
[0067]
This is because if the oxygen ion conductivity of the fuel side electrode reaction layer is high, the equations (3) and (4) that occur between the electrolyte and the fuel electrode can be advanced efficiently. The reason why the output performance is excellent even at an operating temperature of about 700 ° C is that the oxygen ion conductivity of SSZ is sufficiently high even at 700 ° C. Note that NiO in NiO / SSZ and NiO / YSZ is reduced to Ni in the operating atmosphere of the fuel cell, and the layer becomes Ni / SSZ and Ni / YSZ.
H₂+ O^2-→ H₂O + 2e^-                                … (3)
CO + O^2-→ CO₂+ 2e^-                                … (Four)
[0068]
In order to achieve the above object, the 20th invention provides that the interconnector is lanthanum chromite in which Ca is dissolved.
[0069]
According to the present invention, by using lanthanum chromite in which Ca is dissolved, it is easy to produce a film having no gas permeability and an interconnector having high electronic conductivity can be produced.
[0070]
The reason for this is that lanthanum chromite in which a material other than Ca is dissolved requires firing at a temperature higher than 1500 ° C. in order to produce a film having no gas permeability, and the solid oxide fuel cell is fired at this temperature. This is because a reaction occurs between the other constituent materials to lower the output performance.
[0071]
The non-gas permeable membrane shown here is a pressure difference between one side of the interconnector and the opposite side, and is evaluated by the amount of gas permeated through the gap. Gas permeation Q ≦ 2.8 × 10^-9ms^-1Pa^-1(More preferably Q ≦ 2.8 × 10^-Tenms^-1Pa^-1).
[0072]
DETAILED DESCRIPTION OF THE INVENTION
A solid oxide fuel cell according to the present invention will be described with reference to FIG.
FIG. 1 is a view showing a cross section of a cylindrical solid oxide fuel cell. A strip-shaped interconnector 2 and an electrolyte 3 are formed on a cylindrical air electrode support 1, and a fuel electrode 4 is formed on the electrolyte 3 so as not to contact the interconnector 2. When Air flows inside the air electrode support and fuel flows outside, the oxygen in the Air changes to oxygen ions at the interface between the air electrode and the electrolyte, and these oxygen ions reach the fuel electrode through the electrolyte. The fuel gas and oxygen ions react to form water and carbon dioxide. These reactions are shown by equations (3) and (4). Electricity can be taken out by connecting the fuel electrode 4 and the interconnector 2.
H₂+ O^2-→ H₂O + 2e^-                                    … (3)
CO + O^2-→ CO₂+ 2e^-                                    … (Four)
[0073]
FIG. 2 is a cross-sectional view showing a type in which an electrode reaction layer 5 is provided between the air electrode 1 and the electrolyte 3 and a fuel-side electrode reaction layer 6 is provided between the electrolyte 3 and the fuel electrode 4. The electrode reaction layer 5 is a layer provided to efficiently perform the reaction of the formula (1) in which oxygen ions are generated from oxygen gas and electrons from the air electrode side. The oxygen ions generated in the electrode reaction layer are the electrolyte. Move to the fuel electrode side. Then, the reactions shown in the equations (3) and (4) are performed in the fuel side electrode reaction layer 6, and electricity can be taken out by connecting the fuel electrode 4 and the interconnector 2. Therefore, the electrode reaction layer, the electrolyte, and the fuel side electrode reaction layer are important for obtaining high output characteristics up to a low temperature of about 700 ° C.
O₂+ 4e^-→ 2O^2-                                                … (1)
[0074]
The role of the electrode reaction layer in the present invention is to efficiently perform the reaction of the formula (1) in the air atmosphere of the solid oxide fuel cell. For this purpose, the electrode reaction layer is required to have at least a catalyst that ionizes oxygen gas and to have open pores in communication. In order to improve the reaction efficiency, it is preferable to optimize the pore diameter, porosity, and the like. From this viewpoint, the electrode reaction layer preferably has a small pore diameter and a large porosity.
[0075]
The electrode reaction layer in the present invention is not particularly limited as long as it contains at least a catalyst for ionizing oxygen gas. LaAMnO_ThreeLanthanum manganite represented by (A = Sr or Ca), LaSrCoFeO_ThreeAnd lanthanum cobaltite, YSZ, SSZ and the like. The composition of the electrode reaction layer may be the same as that of the air electrode.
[0076]
The material for the electrode reaction layer preferably has high oxygen ion conductivity. Further, it is more preferable that the electrode reaction layer further has electronic conductivity because the reaction of the formula (1) can be further promoted. Furthermore, it is preferable that the material has a thermal expansion coefficient close to that of the electrolyte material, low reactivity with the electrolyte and the air electrode, and good adhesion. If the material is satisfactory for all these characteristics, high output characteristics can be obtained even at a low temperature of about 700 ° C. From the above viewpoint, SSZ and / or cerium oxide, lanthanum manganite / SSZ, lanthanum manganite / cerium oxide, SSZ / cerium oxide, lanthanum manganite / SSZ / cerium oxide and the like are preferable.
[0077]
The catalyst for ionizing oxygen gas contained in the electrode reaction layer in the present invention preferably contains a material having high oxygen ion conductivity. This is because oxygen ions generated in the electrode reaction layer can be efficiently transported to the electrolyte when a material having high oxygen ion conductivity is included. From this viewpoint, the oxygen ion conductivity is 0.1 Scm at 1000 ° C.^-1It is preferable that there is more.
[0078]
0.1Scm at 1000 ℃^-1The materials having the above oxygen ion conductivity include SSZ, cerium oxide, a mixed layer of SSZ and cerium oxide, YSZ, (La_1-xSr_xGa_1-yMg_yO_Three) And (La_1-xSr_xGa_{1-y ―Z}Mg_yCo_zO_ThreeLanthanum gallate represented by). Also, SSZ mixed with lanthanum gallate or SSZ with CeO₂Or Bi₂O_ThreeSince these correspond to this, it is preferable.
[0079]
The electron conductivity contained in the electrode reaction layer in the present invention is 10 Scm at 1000 ° C.^-1There is no limitation in particular as a material used as the above. LaAMnO_ThreeLanthanum manganite represented by (A = Sr or Ca), LaSrCoFeO_ThreeLanthanum cobaltite represented by LaSrFeO_Three, LaSrFeCoO_Three, LaNiO_Three, SmSrCoO_Three, GdSrCoO_ThreeEtc.
[0080]
As lanthanum manganite in the electrode reaction layer in the present invention, LaAMnO_ThreeThe lanthanum manganite represented by (A = Sr or Ca) is preferred, but from the viewpoint of electronic conductivity at 700 ° C or higher, material stability, etc._1-xAx)_yMnO_ThreeThe values of x and y in are preferably in the range of 0.15 ≦ x ≦ 0.3 and 0.97 ≦ y ≦ 1.
[0081]
This is because the electron conductivity decreases in the range of x <0.15 and x> 0.3, the reactivity increases when y <0.97 and the activity of the electrode reaction layer decreases, and when y> 1, it reacts with zirconia. La₂Zr₂O₇This is because the output performance of the cell is lowered in order to produce the insulating layer shown in FIG.
[0082]
The lanthanum manganite in the electrode reaction layer in the present invention may be a solid solution of Ce, Sm, Gd, Pr, Nd, Co, Al, Fe, Cr, Ni, Ca, Sr or the like.
[0083]
The average particle diameter of the raw material powder used for the electrode reaction layer in the present invention is about 0.5 to 10 μm, and the BET value is 0.5 to 20 m.²g^-1The degree is preferred. The reason for this is that in the electrode reaction layer made of a raw material having an average particle size of less than 0.5 μm, there are almost no open pores in communication, so the diffusion of oxygen gas is low, and the reaction of formula (1) cannot be performed efficiently. On the other hand, an electrode reaction layer composed of a raw material larger than 10 μm has low sinterability and low adhesion to the air electrode and electrolyte, resulting in poor output performance. On the other hand, BET value is 0.5m²g^-1In the electrode reaction layer composed of smaller ones, there are few active points that cause the reaction of formula (1), so high output performance cannot be obtained, and the BET value is 20 m.²g^-1This is because in the electrode reaction layer composed of a larger layer, there are almost no open pores communicating with each other, so the diffusion of oxygen gas is low, and the reaction of the formula (1) cannot be performed efficiently.
[0084]
The electrode reaction layer in the present invention may have a structure in which the average particle diameter of the raw material powder is inclined or the BET value is inclined in order to enhance the electrode activity. For example, the average particle diameter from the air electrode side to the electrolyte direction is 5μm, 3μm, 1μm, and the BET value is 1m.²g^-13m²g^-15m²g^-1It may be something like From the viewpoint of efficiently carrying out the reaction of the formula (1), an electrode reaction layer composed of one having an average particle diameter or a BET value inclined is preferred.
[0085]
The BET value shown here is a value obtained by measurement using a flow type specific surface area measuring device Flowsorb II2300 manufactured by Shimadzu Corporation. The particle size distribution is a value obtained by measurement using a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation. Furthermore, the average particle diameter is a median diameter (50% diameter) obtained by measurement using a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation.
[0086]
In the electrode reaction layer in the present invention, the weight ratio in the mixture of lanthanum manganite / SSZ or the like is preferably about 10/90 to 90/10. The reason for this is that if the weight ratio of SSZ is less than 10% by weight, the oxygen ion conductivity in the electrode reaction layer decreases, and the oxygen ions generated by the formula (1) cannot be efficiently sent to the electrolyte, and the output performance is low. On the other hand, if the weight ratio of SSZ is larger than 90% by weight, the electronic conductivity in the electrode reaction layer is lowered, and the reaction shown in the formula (1) is less likely to occur.
[0087]
In the case where a mixture of lanthanum manganite / SSZ or the like is used in the electrode reaction layer in the present invention, a structure having a gradient composition may be used in order to increase the electrode activity. For example, lanthanum manganite / SSZ: 80/20, 50/50, 20/80 from the air electrode side to the electrolyte may be used.
[0088]
There are no particular limitations on the method of preparing the electrode reaction layer material in the present invention. Examples of SSZ, cerium oxide, and lanthanum manganite include a powder mixing method, a coprecipitation method, a spray pyrolysis method, and a sol-gel method.
[0089]
In addition, in the case of raw material synthesis in a mixture such as lanthanum manganite / SSZ, each material is prepared separately and then mixed by a wet method such as spray drying, followed by heat treatment to obtain a mixture or universal stirring Examples thereof include a method of mixing by a dry method of mixing using a mixer or the like and further heat-treating to obtain a mixture.
[0090]
The electrolyte in the present invention preferably has high oxygen ion conductivity, no gas permeability, and no electronic conductivity in the air atmosphere and fuel gas atmosphere of the solid oxide fuel cell. From this viewpoint, zirconia in which yttria or scandia is dissolved is preferable. Further, it may be zirconia in which yttria and scandia are dissolved.
[0091]
The solid solution amount of yttria and scandia in YSZ and SSZ in the present invention is preferably about 3 to 12 mol.
[0092]
The reason why the solid solution range of yttria is preferably 3 to 12 mol% is that if it is less than 3 mol%, the oxygen ion conductivity becomes low, whereas if it exceeds 12 mol%, the crystal phase is rhombohedral in addition to cubic. This is because a crystal phase is precipitated and oxygen ion conductivity is lowered.
[0093]
However, even when the solid solution amount of yttria is in the range of 3 to 12 mol%, the oxygen ion conductivity is high at 900 to 1000 ° C., but greatly decreases below 900 ° C. Therefore, when YSZ is adopted as an electrolyte at a low temperature of about 700 ° C., it is preferably used as a thin film.
[0094]
This is because the resistance loss inside the electrolyte can be reduced by using a thin film, and high output performance can be obtained even at 700 ° C.
[0095]
The thin film shown here is one having an electrolyte film thickness of 50 μm or less.
[0096]
On the other hand, the reason why the scandia solid solution range is limited to 3 to 12 mol% is that if it is less than 3 mol%, the oxygen ion conductivity becomes low. On the other hand, if it exceeds 12 mol%, the crystal phase is in addition to cubic crystals. This is because the plane crystal phase is precipitated and the oxygen ion conductivity is lowered.
[0097]
The reason why the scandia solid solution range is preferable is that the crystal phase is stable in this composition range and the oxygen ion conductivity is high. From the viewpoint of high oxygen ion conductivity, a solution in which scandia is dissolved in 8 to 12 mol% is more preferable.
[0098]
The electrolyte having no gas permeability shown here is a pressure difference between one side of the electrolyte and the opposite side, and is evaluated by the amount of gas permeated between them, and the amount of gas permeated Q ≦ 2.8 × 10^-9ms^-1Pa^-1(More preferably Q ≦ 2.8 × 10^-Tenms^-1Pa^-1).
[0099]
The electrolyte in the present invention includes CeO₂, Sm₂O_Three, Gd₂O_3,Bi₂O_ThreeOr the like in which 5 mol% or less is dissolved. In particular, in zirconia in which scandia is dissolved, it is preferable to include a small amount of these compositions because oxygen ion conductivity is increased and low-temperature sintering is possible. Further, a small amount of a sintering aid may be added in order to produce an electrolyte having no gas permeability. Al as a sintering aid₂O_Three, SiO₂And so on.
[0100]
The method for producing the electrolyte raw material in the present invention is not particularly limited as long as it is a method capable of uniformly dissolving scandia or yttria. The coprecipitation method is common.
[0101]
The air electrode in the present invention preferably has high electronic conductivity and high oxygen gas permeability in the air atmosphere of the solid oxide fuel cell. From this point of view, LaAMnO_ThreeLanthanum manganite represented by (A = Sr or Ca), LaSrCoFeO_ThreeLanthanum cobaltite represented by LaSrFeO_Three, LaSrFeCoO_Three, LaNiO_Three, SmSrCoO_Three, GdSrCoO_ThreeEtc. are preferable.
[0102]
As the air electrode in the present invention, LaAMnO_ThreeThe lanthanum manganite represented by (A = Sr or Ca) is preferred, but from the viewpoint of electronic conductivity at 700 ° C or higher, material stability, etc._1-xAx)_yMnO_ThreeThe values of x and y in are preferably in the range of 0.15 ≦ x ≦ 0.3 and 0.97 ≦ y ≦ 1.
[0103]
This is because the electron conductivity decreases in the range of x <0.15 and x> 0.3, the activity of the electrode reaction layer decreases when y <0.97, and the reaction with zirconia occurs when y> 1.₂Zr₂O₇This is because the output performance of the cell is lowered in order to produce the insulating layer shown in FIG.
[0104]
In the present invention, the lanthanum manganite in the air electrode may be a solid solution of Ce, Sm, Gd, Pr, Nd, Co, Al, Fe, Cr, Ni, Ca, Sr and the like.
[0105]
There are no particular limitations on the method for producing the air electrode raw material in the present invention. Examples of the method include a powder mixing method, a coprecipitation method, a spray pyrolysis method, and a sol-gel method.
[0106]
The pore diameter of the air electrode in the present invention is not particularly limited as long as it is larger than the pore diameter of the electrode reaction layer, but other characteristics include high electronic conductivity and high oxygen gas permeability. And having good adhesion to the electrode reaction layer is preferable. Further, in the type in which the air electrode shown in the present embodiment is a support, the air electrode itself is required to have high strength, so that it has higher strength. From these viewpoints, the pore diameter of the air electrode is preferably about 2 to 30 μm, and considering the high strength, about 2 to 20 μm is preferable.
[0107]
The porosity of the air electrode in the present invention is not particularly limited as long as it is equal to or higher than the porosity of the electrode reaction layer, but as other characteristics, it has high electronic conductivity and high oxygen gas permeability. And what has favorable adhesiveness with an electrode reaction layer is preferable. Further, in the type in which the air electrode shown in the present embodiment is a support, the air electrode itself is required to have high strength, so that it has higher strength. From this viewpoint, the porosity of the air electrode is preferably about 10 to 50%, and about 10 to 45% in consideration of having high strength.
[0108]
The thickness of the air electrode in the present invention is not particularly limited as long as it is thicker than the electrode reaction layer, but as other characteristics, it has high electronic conductivity, high oxygen gas permeability, Those having good adhesion are preferred. Further, in the type in which the air electrode shown in the present embodiment is a support, the air electrode itself is required to have high strength, so that it has higher strength. From this point of view, the thickness of the air electrode is preferably about 30 μm to 3 mm, and is preferably about 1 to 3 mm in consideration of the case of using the support.
[0109]
The high strength shown here indicates that the crushing strength indicates 10 MPa or more. The measurement of the crushing strength was obtained by performing a test by the following method.
[0110]
The sample is placed between the compression jigs of the test machine, and is pressed and broken from above and below, and the load value at that time is used to calculate from the following formula.
σr = P × (D−d) / (I × d²) … (Five)
(Σr: crushing strength, P: fracture load, D: sample outer diameter, d: wall thickness, I: sample length)
[0111]
The fuel electrode in the present invention is preferably one that has high electronic conductivity and high fuel gas permeability in the fuel gas atmosphere of the solid oxide fuel cell, and can efficiently perform the reactions (3) and (4). From this viewpoint, preferred materials include NiO / YSZ. NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / YSZ.
[0112]
From the viewpoint of efficiently performing the reactions (3) and (4) and improving the output performance, it is preferable to provide a fuel side electrode reaction layer between the electrolyte and the fuel electrode.
[0113]
The fuel-side electrode reaction layer in the present invention is preferably NiO / SSZ which is excellent in both electronic conductivity and oxygen ion conductivity. NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / SSZ. The ratio of NiO / SSZ is preferably 10/90 to 50/50 by weight. This is because the electron conductivity is too low below 10/90, while the oxygen ion conductivity is too low above 50/50.
[0114]
The solid solution amount of scandia of SSZ in the NiO / SSZ of the present invention is preferably 3 to 12 mol%. This is because, within this range, the oxygen ion conductivity is high and the reactions (3) and (4) can be promoted. In addition, since the oxygen ion conductivity is high even at a low temperature of about 700 ° C., a solid oxide fuel cell having high output performance up to a low temperature of about 700 ° C. can be provided.
[0115]
The SSZ in the NiO / SSZ of the present invention is further CeO₂, Sm₂O_Three, Gd₂O_Three, Bi₂O_ThreeEtc. may be dissolved in the order of 5 mol% or less. Two or more of them may be dissolved. When these materials are dissolved, it is preferable to include them because not only the oxygen ion conductivity can be improved but also the electron conductivity can be expected in a fuel gas atmosphere.
[0116]
A layer in which NiO, SSZ, and cerium oxide are uniformly mixed at a specified weight ratio (hereinafter referred to as NiO / SSZ / cerium oxide) from the viewpoint of high oxygen ion conductivity and high electron conductivity in a fuel gas atmosphere. It may be expressed as NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / SSZ / cerium oxide.
[0117]
The cerium oxide shown here is not particularly limited as long as it is an oxide containing cerium. General formula (CeO₂)_1-2X(B₂O_Three)_X (However, any one of B = Sm, Gd, and Y, 0.05 ≦ X ≦ 0.15) is preferable because of high oxygen ion conductivity.
[0118]
The fuel electrode in the present invention preferably has a high electronic conductivity in order to reduce the IR loss. From this viewpoint, the ratio of NiO / YSZ is preferably 50/50 to 90/10 by weight. The reason for this is that the electron conductivity is low below 50/50, while the output performance is reduced by agglomeration of Ni particles above 90/10.
[0119]
The composition of the fuel electrode in the present invention may be NiO / SSZ or zirconia in which NiO / calcium is dissolved in addition to NiO / YSZ (hereinafter referred to as NiO / CSZ). YSZ is preferable because YSZ is cheaper than SSZ, but NiO / CSZ is most preferable from the viewpoint of cost because CSZ is cheaper than YSZ. Note that NiO / CSZ is Ni / CSZ in fuel cell power generation.
[0120]
The method for synthesizing the fuel electrode raw material in the present invention is not particularly limited as long as the fuel electrode materials such as NiO / SSZ and YSZ are uniformly mixed. Examples include a coprecipitation method and a spray drying method.
[0121]
The interconnector in the present invention is preferably one having high electronic conductivity, no gas permeability, and no oxygen ion conductivity in the air atmosphere and fuel gas atmosphere of the solid oxide fuel cell. From this viewpoint, lanthanum chromite is preferable.
[0122]
Since lanthanum chromite is difficult to sinter, it is difficult to produce an interconnector having no gas permeability at the firing temperature of the solid oxide fuel cell (1500 ° C. or lower). In order to improve sinterability, it is preferable to use Ca, Sr, and Mg in solid solution. A solution in which Ca is dissolved is most preferable because it has the highest sinterability and can produce a film having no gas permeability at the same temperature as other materials of the solid oxide fuel cell.
[0123]
There is no particular limitation on the solid solution amount of lanthanum chromite in which Ca used in the interconnector in the present invention is dissolved. As the Ca solid solution amount increases, the electronic conductivity increases. However, since the stability of the material decreases, the Ca solid solution amount is preferably about 10 to 40 mol%.
[0124]
Regarding the method for producing the interconnector raw material in the present invention, it is preferable that the composition of the lanthanum chromite in which Ca is dissolved is made uniform. From this viewpoint, the spray pyrolysis method, the citrate method and the like are preferable.
[0125]
The shape of the solid oxide fuel cell in the present invention is not particularly limited, and may be either a flat plate type or a cylindrical type. In the flat plate type, the interconnector is called a separator, and the role is the same as that of the interconnector. In the case of a separator, a metal such as stainless steel may be used.
[0126]
The solid oxide fuel cell according to the present invention can also be applied to a microtube type (outer diameter of 10 mm or less, preferably 5 mm or less).
[0127]
【Example】
(Example 1)
The cylindrical solid oxide fuel cell shown in FIG. 1 was used. That is, a belt-shaped interconnector 2 and electrolyte 3 on a cylindrical air electrode support 1 and a fuel electrode 4 so as not to contact the interconnector on the electrolyte were used. In addition, as shown in FIG. 2, an electrode reaction layer 5 is formed between the air electrode and the electrolyte, and a fuel side electrode reaction layer 6 is formed between the fuel electrode 4 and the electrolyte 3.
[0128]
 (1) Production of air electrode support
The composition of the air electrode is La_0.75Sr_0.25MnO_ThreeAn air electrode raw material powder was obtained from lanthanum manganite in which Sr represented by the composition was dissolved, prepared by a coprecipitation method and then heat-treated. The average particle size was 30 μm. A cylindrical molded body was produced by an extrusion molding method. Further, firing was performed at 1500 ° C. to obtain an air electrode support. The pore diameter of the air electrode support was 14 μm, the porosity was 45%, and the wall thickness was 1.5 mm.
[0129]
(2) Preparation of electrode reaction layer
The electrode reaction layer is lanthanum manganite / SSZ, and the composition and weight ratio thereof are La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50 was used. Using nitrate aqueous solutions of La, Sr, Mn, Zr and Sc, the mixture was prepared to have the above composition, and then oxalic acid was added and precipitated. The precipitate was further heat-treated to control the particle size to obtain a raw material powder. The average particle size was 2 μm. 40 parts by weight of the electrode reaction layer powder is 100 parts by weight of a solvent (ethanol), 2 parts by weight of a binder (ethyl cellulose), 1 part by weight of a dispersant (polyoxyethalene alkyl sonic ester), 1 part of an antifoaming agent (sorbitan sesquiolate) After mixing with parts by weight, the slurry was sufficiently stirred to prepare a slurry. The slurry viscosity was 100 mPas. The slurry was formed on the air electrode support (outer diameter 15 mm, wall thickness 1.5 mm, effective length 400 mm) by the slurry coating method, and then sintered at 1400 ° C. The thickness was 20 μm.
[0130]
(3) Preparation of electrolyte slurry:
The electrolyte material is SSZ and the composition is 90 mol% ZrO₂-10mol% Sc₂O_ThreeIt is. ZrO₂ Was dissolved in 3N or more concentrated nitric acid heated at 100 ° C. and diluted with distilled water to obtain an aqueous nitrate solution. Sc₂O_ThreeA nitrate aqueous solution was obtained from the same method. Each nitrate aqueous solution was prepared so that it might become the said composition, and the oxalic acid aqueous solution was added and coprecipitated. The liquid obtained by coprecipitation was dried at about 200 ° C., pyrolyzed at 500 ° C., and further heat-treated at 800 ° C. for 10 hours to obtain a raw material powder. The average particle size was 0.5 μm. 40 parts by weight of the powder, 100 parts by weight of a solvent (ethanol), 2 parts by weight of a binder (ethyl cellulose), 1 part by weight of a dispersant (polyoxyethalene alkylsonate), 1 part by weight of an antifoaming agent (sorbitan sesquiolate) After mixing, the slurry was sufficiently stirred to prepare a slurry. The slurry viscosity was 140 mPas.
[0131]
(4) Preparation of electrolyte
A film was formed on the electrode reaction layer by a slurry coating method and baked at 1400 ° C. The thickness of the obtained electrolyte was 30 μm. Note that a portion where the interconnector is formed in a later process is masked so that the film is not applied.
[0132]
(5) Slurry preparation of fuel side electrode reaction layer
The material for the fuel electrode reaction layer is NiO / SSZ, and the composition is NiO / 90 mol% ZrO.₂-10mol% Sc₂O_ThreeThen, using nitrate aqueous solutions of Ni, Zr and Sc to prepare the above composition, oxalic acid was added and precipitated. The precipitate was further subjected to a heat treatment to control the particle diameter to obtain a raw material. The composition of the fuel electrode reaction layer and its weight ratio are NiO / 90 mol% ZrO₂-10mol% Sc₂O_Three = 20/80 and 50/50 were produced, and the average particle size was 0.5 μm for both. 100 parts by weight of the powder, 500 parts by weight of an organic solvent (ethanol), 10 parts by weight of a binder (ethyl cellulose), 5 parts by weight of a dispersant (polyoxyethalene alkyl phosphate ester), 1 part by weight of an antifoaming agent (sorbitan sesquiolate) Parts and 5 parts by weight of a plasticizer (DBP) were mixed, and then sufficiently stirred to prepare a slurry. The viscosity of this slurry was 70 mPas.
[0133]
(6) Preparation of fuel side electrode reaction layer
150cm area²The battery is masked to become NiO / 90 mol% ZrO on the electrolyte by slurry coating.₂-10mol% Sc₂O_Three (Average particle diameter) = 20/80 (0.5 μm) and 50/50 (0.5 μm) were formed in this order. The film thickness (after firing) was 10 μm.
[0134]
(7) Fuel electrode slurry preparation:
The material of the anode is NiO / YSZ, and the composition is NiO / 90 mol% ZrO₂-10mol% Y₂O_ThreeThen, using nitrate aqueous solutions of Ni, Zr and Y, the mixture was prepared to have the above composition, and then oxalic acid was added and precipitated. The precipitate was further subjected to heat treatment to control the particle size, and a raw material was obtained. Composition and weight ratio of NiO / 90 mol% ZrO₂-10mol% Y₂O_Three = 70/30, and the average particle size was 5 μm. 100 parts by weight of the powder, 500 parts by weight of an organic solvent (ethanol), 20 parts by weight of a binder (ethyl cellulose), 5 parts by weight of a dispersant (polyoxyethalene alkyl phosphate), 1 part by weight of an antifoaming agent (sorbitan sesquiolate) Parts and 5 parts by weight of a plasticizer (DBP) were mixed, and then sufficiently stirred to prepare a slurry. The viscosity of this slurry was 250 mPas.
[0135]
(8) Fabrication of fuel electrode
Fuel sideA fuel electrode was formed on the electrode reaction layer by a slurry coating method. The film thickness (after firing) was 90 μm. further,Fuel sideThe electrode reaction layer and the fuel electrode were co-fired at 1400 ° C.
[0136]
(9) Fabrication of interconnector:
Interconnector composition is La_0.80Ca_0.20CrO_ThreeA lanthanum chromite in which Ca represented by the formula (1) was dissolved was prepared by a spray pyrolysis method and then subjected to a heat treatment. The average particle size of the obtained powder was 1 μm. 40 parts by weight of the powder, 100 parts by weight of a solvent (ethanol), 2 parts by weight of a binder (ethyl cellulose), 1 part by weight of a dispersant (polyoxyethalene alkylsonate), 1 part by weight of an antifoaming agent (sorbitan sesquiolate) After mixing, the slurry was sufficiently stirred to prepare a slurry. The slurry viscosity was 100 mPas. The interconnector was formed into a film by a slurry coating method and baked at 1400 ° C. The thickness after firing was 40 μm.
[0137]
(Example 2)
The electrode reaction layer material is SSZ, and the composition is 90 mol% ZrO.₂-10mol% Sc₂O_ThreeThe same procedure as in Example 1 was conducted except that the firing temperature was 1350 ° C.
[0138]
(Example 3)
The material of the electrode reaction layer is La_0.75Sr_0.25MnO_ThreeExample 1 was repeated except that lanthanum manganite in which Sr represented by the composition was dissolved was used, and the average particle diameter of the raw material was 2 μm. At this time, the pore diameter was 2 μm and the porosity was 20%.
[0139]
(Comparative Example 1)
Example 1 was repeated except that no electrode reaction layer was provided between the air electrode and the electrolyte.
[0140]
(Power generation test)
Cells obtained in Examples 1 to 3 and Comparative Example 1 (effective area of fuel electrode: 150 cm²) Was used to conduct a power generation test. The operating conditions at this time were as follows.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0141]
[Table 1]

Table 1 shows a current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. At the same current density, the higher the power generation potential, the better the output performance of the solid oxide fuel cell. As shown in Table 1, it can be seen that the power generation potential is higher than that of Comparative Example 1. From the above results, it was confirmed that it is preferable to provide an electrode reaction layer between the air electrode and the electrolyte.
[0142]
About pore size
(Example 4)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, the average particle diameter of the raw material was 0.5 μm, and after film formation on the air electrode surface by the slurry coating method, it was the same as in Example 1 except that it was sintered at 1350 ° C. The method was
[0143]
(Example 5)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, and the average particle diameter of the raw material was 5 μm, and after forming a film on the air electrode surface by a slurry coating method, it was the same as in Example 1 except that it was sintered at 1400 ° C. It was a method.
[0144]
(Example 6)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, and the average particle diameter of the raw material was 10 μm, the same as in Example 1 except that the film was formed on the air electrode surface by a slurry coating method and then sintered at 1400 ° C. It was a method.
[0145]
(Example 7)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, the average particle diameter of the raw material was 0.2 μm, and after film formation on the air electrode surface by a slurry coating method, it was the same as in Example 1 except that it was sintered at 1350 ° C. The method was
[0146]
(Example 8)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, and the average particle diameter of the raw material was 15 μm, and after the film was formed on the air electrode surface by the slurry coating method, it was the same as in Example 1 except that it was sintered at 1400 ° C. It was a method.
[0147]
(Example 9)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, and the average particle diameter of the raw material was 0.5 μm, and after film formation on the air electrode surface by the slurry coating method, the same as in Example 1 except that it was sintered at 1400 ° C. The method was
[0148]
(Power generation test)
Cells obtained in Example 1 and Examples 4 to 9 (effective area of fuel electrode: 150 cm²) Was used to conduct a power generation test. The operating conditions at this time were as follows.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
Further, after the power generation test, the pore diameters of the electrode reaction layers in Example 1 and Examples 4 to 9 were measured.
[0149]
[Table 2]

Table 2 shows a current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. Although the same material is used, it can be seen that the power generation potential varies depending on the pore diameter of the electrode reaction layer. In Examples 1, 4-6, and 9, the power generation potential is high, but in Examples 7 and 8, the potential is reduced. However, since it is higher than Comparative Example 1 shown in Table 1, there is no particular problem. From the above results, it was confirmed that the pore diameter of the electrode reaction layer is more preferably about 0.1 to 10 μm which exhibits a high value of the power generation potential.
[0150]
About porosity
After the power generation test, the porosity of the electrode reaction layer in Example 1 and Examples 4 to 9 was measured.
[0151]
[Table 3]

Table 3 shows current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. Although the same material is used, it can be seen that the power generation potential varies depending on the porosity of the electrode reaction layer. In Examples 1, 4-6, and 9, the power generation potential is high, but in Examples 7 and 8, the potential is reduced. In Examples 7 and 8, although the potential is lowered, there is no problem because it is higher than Comparative Example 1. From the above results, it was confirmed that the porosity of the electrode reaction layer was more preferably about 3 to 40% exhibiting a high power generation potential.
[0152]
About the thickness of the electrode reaction layer
(Example 10)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, and the same as Example 1 except that the thickness was 3 μm.
[0153]
(Example 11)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50 and the same as Example 1 except that the thickness was 5 μm.
[0154]
(Example 12)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50 and the same as Example 1 except that the thickness was 30 μm.
[0155]
(Example 13)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, except that the thickness was 50 μm.
[0156]
(Example 14)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, except that the thickness was 2 μm.
[0157]
(Example 15)
The composition of the electrode reaction layer is La_0.75Sr_0.25MnO_Three/ 90 mol% ZrO₂-10mol% Sc₂O_Three= 50/50, except that the thickness was 55 μm.
[0158]
(Power generation test)
Cells obtained in Example 1 and Examples 10 to 15 (effective area of fuel electrode: 150 cm²) Was used to conduct a power generation test. The operating conditions at this time were as follows.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0159]
[Table 4]

Table 4 shows current density at 800 ° C and 0.3 Acm.^-2The result of the electric power generation potential in is shown. Although the same material is used, it can be seen that the power generation potential varies depending on the thickness of the electrode reaction layer. It can be seen that in Examples 1 and 10 to 13, the power generation potential is high, but in Examples 14 and 15, the potential is lowered. In Examples 14 and 15, although the potential is lowered, it is higher than that in Comparative Example 1, so there is no problem. From the above results, it was confirmed that the thickness of the electrode reaction layer is preferably about 3 to 50 μm exhibiting a high power generation potential. Furthermore, when Examples 1 and 10 to 13 are compared with each other, Examples 1, 11 and 12 have higher output performance. Therefore, it was confirmed that the thickness of the electrode reaction layer is more preferably 5 to 30 μm.
[0160]
About electrode reaction layer materials
(Example 16)
The material of the electrode reaction layer is cerium oxide, and the composition is (CeO₂)_0.8(Sm₂O_Three)_{0. 1}Except for the above, the procedure was the same as in Example 1.
[0161]
(Example 17)
The material of the electrode reaction layer is SSZ / cerium oxide, and the composition is 90 mol% ZrO.₂-10mol% Sc₂O_Three/ (CeO₂)_0.8(Sm₂O_Three)_{0. 1}= Same as Example 1 except for 50/50.
[0162]
(Example 18)
The electrode reaction layer material is lanthanum manganite / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.8(Sm₂O_Three)_{0. 1}= Same as Example 1 except for 50/50.
[0163]
(Example 19)
The electrode reaction layer material is lanthanum manganite / SSZ / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ 90mol% ZrO₂-10mol% Sc₂O_Three / (CeO₂)_0.8(Sm₂O_Three)_{0. 1}= 50/25/25. La for raw material synthesis_0.75Sr_0.25MnO_Three/ 90mol% ZrO₂-10mol% Sc₂O_ThreeAnd La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.8(Sm₂O_Three)_{0. 1}Each of the powders prepared by the coprecipitation method is further mixed with La_0.75Sr_0.25MnO_Three/ 90mol% ZrO₂-10mol% Sc₂O_Three / (CeO₂)_0.8(Sm₂O_Three)_{0. 1}= 50/25/25 The mixture was mixed and heat-treated. Except these, the procedure was the same as in Example 1.
[0164]
(Example 20)
The electrode reaction layer material is YSZ and the composition is 92 mol% ZrO.₂-8mol% Y₂O_ThreeThe procedure was the same as in Example 1 except that.
[0165]
(Example 21)
The electrode reaction layer material is lanthanum manganite / YSZ, and the composition is La_0.75Sr_0.25MnO_Three/ 92mol% ZrO₂-8mol% Y₂O_Three= Same as Example 1 except for 50/50.
[0166]
(Power generation test)
Test cells of Examples 1, 2, 16 to 21 and Comparative Example 1 (effective area of fuel electrode: 150 cm²) Was used to perform the following power generation test. The operating conditions at this time were as follows.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 700-1000 ° C
(4) Current density: 0.3Acm^-2
[0167]
FIG. 3 shows the result of the power generation potential at the power generation temperature. It can be seen that Examples 1, 18, and 19 exhibit a high potential at 700 to 1000 ° C. In Examples 2, 16, and 17, it can be seen that although it is inferior to Examples 1, 18, and 19, it exhibits a relatively high potential up to 700 ° C. In Examples 20 and 21, a high potential is exhibited at 900 to 1000 ° C., but it can be seen that a decrease in potential increases at 900 ° C. or less. In contrast, Comparative Example 1 is lower than the example at 1000 ° C., and it can be seen that the potential decrease further increases as the power generation temperature decreases. From the above results, it was confirmed that the power generation potential was high and preferable as compared with Comparative Example 1. When the electrode reaction layer is YSZ and lanthanum manganite / YSZ, it has a high output performance at 900 to 1000 ° C, and when the electrode reaction layer is SSZ, cerium oxide, and SSZ / cerium oxide, even at 900 ° C or less It has been found that it has high output performance and is preferable. Furthermore, when the electrode reaction layer was lanthanum manganite / SSZ, lanthanum manganite / cerium oxide, and lanthanum manganite / SSZ / cerium oxide, it was confirmed that the output performance was excellent and more preferable even at about 700 ° C.
[0168]
On the amount of scandia dissolved in the electrode reaction layer
(Example 22)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 97 mol% ZrO₂-3mol% Sc₂O_Three= Same as Example 1 except for 50/50.
[0169]
(Example 23)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 92 mol% ZrO₂-8mol% Sc₂O_Three= Same as Example 1 except for 50/50.
[0170]
(Example 24)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 88 mol% ZrO₂-12mol% Sc₂O_Three= Same as Example 1 except for 50/50.
[0171]
(Example 25)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 98 mol% ZrO₂-2mol% Sc₂O_Three= Same as Example 1 except for 50/50.
[0172]
(Example 26)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 85 mol% ZrO₂-15mol% Sc₂O_Three= Same as Example 1 except for 50/50.
[0173]
The batteries of Example 1 and Examples 22 to 26 were subjected to a power generation test under the power generation conditions shown below.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0174]
[Table 5]

[0175]
Table 5 shows a current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. In Examples 1 and 22 to 24, the potential is high, whereas in Examples 25 and 26, the potential is lowered. However, in Examples 25 and 26, compared to Comparative Example 1 shown in Table 1, a much higher potential was exhibited, so that it was found that there was no problem as long as this level of decrease was achieved. From the fact that the potential is high, it was confirmed that the amount of scandia solid solution in SSZ of the electrode reaction layer is preferably in the range of 3 to 12 mol%. Further, when the data of Example 1 and Examples 22 to 24 are compared, the potential of Example 22 is lower than the others, so that the amount of scandia solid solution is more preferably 8 to 12 mol%. It could be confirmed.
[0176]
CeO in SSZ₂Etc.
(Example 27)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 88mol% ZrO₂-10mol% Sc₂O_Three-2mol% CeO₂ = Same as Example 1 except for 50/50.
[0177]
(Example 28)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 85mol% ZrO₂-10mol% Sc₂O_Three-5mol% CeO₂ = Same as Example 1 except for 50/50.
[0178]
(Example 29)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 84mol% ZrO₂-10mol% Sc₂O_Three-6mol% CeO₂ = Same as Example 1 except for 50/50.
[0179]
(Example 30)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 88mol% ZrO₂-10mol% Sc₂O_Three-2mol% Bi₂O_Three = Same as Example 1 except for 50/50.
[0180]
(Example 31)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 88mol% ZrO₂-10mol% Sc₂O_Three-2mol% Y₂O_Three = Same as Example 1 except for 50/50.
[0181]
(Example 32)
The composition of the electrode reaction layer and its weight ratio are La_0.75Sr_0.25MnO_Three/ 88mol% ZrO₂-10mol% Sc₂O_Three-1mol% Y CeO₂-1mol% Bi₂O_Three = Same as Example 1 except for 50/50.
[0182]
The batteries of Example 1 and Examples 27 to 32 were subjected to a power generation test under the power generation conditions shown below.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0183]
[Table 6]

Table 6 shows current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. When Example 1 and Examples 27 to 29 were compared with each other, Example 27 and Example 28 showed higher potentials, but Example 29 tended to be lower. In Examples 30 and 31, the potential was not changed from that in Example 1, but it was confirmed that the sinterability of the electrode reaction layer material was improved. In Example 32, it was confirmed that the potential was increased and the sinterability of the electrode reaction layer material was improved. Based on the above results, CeO₂It was confirmed that the output performance was improved when 5 mol% or less was dissolved, and it was found preferable. Y₂O_ThreeOr Bi₂O_ThreeIt was found that sinterability was improved when the solution was dissolved, which was preferable. Gd₂O_Three, Yb₂O_ThreeEven when other rare earth oxides such as 5 mol% or less are dissolved, it is considered preferable because it can be easily estimated that either the output performance is improved or the sinterability is improved. .
[0184]
(CeO₂)_1-2x(Sm₂O_Three)_xabout
(Example 33)
The electrode reaction layer material is lanthanum manganite / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.9(Sm₂O_Three)_0.05= Same as Example 1 except for 50/50.
[0185]
Example 34
The electrode reaction layer material is lanthanum manganite / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.7(Sm₂O_Three)_0.15= Same as Example 1 except for 50/50.
[0186]
(Example 35)
The electrode reaction layer material is lanthanum manganite / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.75(Sm₂O_Three)_0.025= Same as Example 1 except for 50/50.
[0187]
Example 36
The electrode reaction layer material is lanthanum manganite / cerium oxide, and the composition is La_0.75Sr_0.25MnO_Three/ (CeO₂)_0.65(Sm₂O_Three)_0.175= Same as Example 1 except for 50/50.
[0188]
The batteries of Example 18 and Examples 33 to 36 were subjected to a power generation test under the power generation conditions shown below.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0189]
[Table 7]

Table 7 shows current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. Comparing Example 18 and Examples 33 to 36, it can be seen that the potential is somewhat lower when the x value of Example 35 and Example 36 is reached. From the above results (CeO₂)_1-2x(Sm₂O_Three)_xIt was confirmed that the range of 0.05 ≦ x ≦ 0.15 is more preferable. In this example, only Sm was used, but it was considered preferable because Gd and Y can be easily estimated to have the same effect.
[0190]
On the composition of lanthanum manganite in the electrode reaction layer
(Example 37)
The composition of the electrode reaction layer and its weight ratio are La_0.75Ca_0.25MnO_Three/ 90mol% ZrO₂-10mol% Sc₂O_Three = Same as Example 1 except for 50/50.
[0191]
The batteries of Example 1 and Example 37 were subjected to a power generation test under the following power generation conditions. (1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 800 ° C
(4) Current density: 0.3Acm^-2
[0192]
[Table 8]

Table 8 shows a current density of 0.3 Acm at 800 ° C.^-2The result of the electric power generation potential in is shown. Since the potential hardly changed in Example 1 and Example 31, it was confirmed that the lanthanum manganite in the electrode reaction layer may be either lanthanum manganite in which Ca or Sr is dissolved.
[0193]
About electrolyte materials
(Example 38)
The electrolyte material is YSZ and the composition is 92 mol% ZrO₂-8mol% Y₂O_ThreeExcept that, it was the same as Example 1.
[0194]
Test cells of Examples 1 and 38 and Comparative Example 1 (Fuel electrode effective area: 150 cm²) Was used to perform the following power generation test. The operating conditions at this time were as follows.
(1) Fuel: (H₂+ 11% H₂O): N₂  = 1: 2
(2) Oxidizing agent: Air
(3) Power generation temperature: 700-1000 ° C
(4) Current density: 0.3Acm^-2
[0195]
Fig. 4 shows the results of the power generation potential at the power generation temperature. In Example 38, the potential is almost the same at 1000 ° C., but the potential decreases when the temperature is 900 ° C. or less. It can be seen that the potential difference is considerably larger than that in Example 1 at about 700 ° C. However, it can be seen that there is a large difference from Comparative Example 1. From the above results, it was confirmed that SSZ is preferable for the power generation temperature of 900 ° C. or lower, but it is confirmed that the electrolyte is almost the same at 900 ° C. or higher, and that there is no problem even if the electrolyte is YSZ.
[0196]
By interposing the electrode reaction layers shown in Example 1, Example 19 and Example 27, a solid oxide fuel cell having a high potential of 0.6 V or higher even at a low temperature of about 700 ° C. could be provided.
[0197]
【The invention's effect】
As is clear from the above description, a solid oxide fuel cell excellent in output performance can be obtained by providing an electrode reaction layer having at least a catalyst that ionizes oxygen gas between the air electrode and the electrolyte and having open pores that communicate with each other. Can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a cylindrical type solid oxide fuel cell.
2 is a cross-sectional view showing in detail an air electrode, electrolyte, and fuel electrode configuration of the solid oxide fuel cell shown in FIG. 1. FIG.
FIG. 3 is a graph showing a relationship between a power generation temperature (horizontal axis) and a power generation potential (vertical axis) of a test battery.
FIG. 4 is a graph showing the relationship between the power generation temperature (horizontal axis) and the power generation potential (vertical axis) of the test battery.
[Explanation of symbols]
1: Air electrode support
2: Interconnector
3: Electrolyte
4: Fuel electrode
5: Electrode reaction layer
6: Fuel side electrode reaction layer

Claims (18)

A solid electrolyte fuel cell comprising an air electrode, an electrolyte, and a fuel electrode, and an electrode reaction layer interposed between the air electrode and the electrolyte, wherein the electrode reaction layer ionizes at least oxygen gas The electrode reaction layer is a layer in which lanthanum manganite and scandia dissolved in zirconia are uniformly mixed at a predetermined weight ratio, lanthanum manganite and cerium oxide. Any one of the group consisting of a layer in which lanthanum manganite and scandia are solid-solved and a layer in which zirconia and cerium oxide are uniformly mixed in a predetermined weight ratio A solid oxide fuel cell characterized by being excellent in output performance even at an operating temperature of 700 to 900 ° C. A solid electrolyte fuel cell comprising an air electrode, an electrolyte, and a fuel electrode, and an electrode reaction layer interposed between the air electrode and the electrolyte, wherein the electrode reaction layer ionizes at least oxygen gas The electrode reaction layer is a layer in which lanthanum manganite and scandia dissolved in zirconia are uniformly mixed at a predetermined weight ratio, lanthanum manganite and cerium oxide. Any one of the group consisting of a layer in which lanthanum manganite and scandia are solid-solved and a layer in which zirconia and cerium oxide are uniformly mixed in a predetermined weight ratio a body, wherein the electrolyte is a zirconia is dissolved yttria or scandia, and characterized in that also excellent output performance at operating temperatures of 700 to 900 ° C. Solid oxide fuel cells.   3. The solid oxide fuel cell according to claim 1, wherein the electrode reaction layer has a pore diameter of 0.1 to 10 μm.   4. The solid oxide fuel cell according to claim 1, wherein a pore diameter of the electrode reaction layer is smaller than a pore diameter of the air electrode. 5.   The solid oxide fuel cell according to any one of claims 1 to 4, wherein the electrode reaction layer has a porosity of 3 to 40%.   6. The solid oxide fuel cell according to claim 1, wherein a porosity of the electrode reaction layer is equal to or less than a porosity of the air electrode.   7. The solid oxide fuel cell according to claim 1, wherein the electrode reaction layer has a thickness of 3 to 50 [mu] m.   The solid oxide fuel cell according to claim 7, wherein the electrode reaction layer has a thickness of 5 to 30 μm.   The solid oxide fuel cell according to claim 1, wherein a thickness of the electrode reaction layer is smaller than a thickness of the air electrode.   10. The solid oxide fuel cell according to claim 1, wherein the electrode reaction layer further includes a material having an electronic conductivity of 10 Scm −1 or more at 1000 ° C. 10.   11. The solid oxide fuel cell according to claim 1, wherein in the zirconia in which the scandia is dissolved, a scandia solid solution amount is 3 to 12 mol%.   In the zirconia in which scandia is dissolved, rare earth oxides such as CeO2, Gd2O3, Y2O3, and Yb2O3 and one or more oxides of Bi2O3 are further solid-dissolved. The solid oxide fuel cell according to claim 1, wherein the solid oxide fuel cell is dissolved.   2. The solid oxide fuel cell according to claim 1, wherein the lanthanum manganite in the electrode reaction layer is made of lanthanum manganite represented by LaAMnO 3 (where A = Ca or Sr).   The cerium oxide in the electrode reaction layer is represented by the general formula (CeO2) 1-2X (B2O3) X / 2 (B = Sm, Gd, Y, 0.05 ≦ X ≦ 0.15) The solid oxide fuel cell according to claim 1.   15. The solid oxide fuel cell according to claim 1, wherein the air electrode is lanthanum manganite represented by LaAMnO 3 (where A = Ca or Sr). .   The solid electrolyte fuel according to any one of claims 1 to 15, wherein the fuel electrode comprises a layer in which zirconia in which NiO and yttria are dissolved is uniformly mixed at a predetermined weight ratio. battery.   A fuel-side electrode reaction layer comprising a layer in which zirconia in which NiO and scandia are dissolved is uniformly mixed at a predetermined weight ratio is interposed between the fuel electrode and the electrolyte. Item 18. The solid oxide fuel cell according to any one of Items 1 to 16.   18. The solid oxide fuel cell according to claim 1, wherein the interconnector in the solid oxide fuel cell is lanthanum chromite in which Ca is dissolved.

Images