JP2004063226A - Fuel battery cell, its manufacturing method, and fuel battery - Google Patents

Fuel battery cell, its manufacturing method, and fuel battery Download PDF

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JP2004063226A
JP2004063226A JP2002218949A JP2002218949A JP2004063226A JP 2004063226 A JP2004063226 A JP 2004063226A JP 2002218949 A JP2002218949 A JP 2002218949A JP 2002218949 A JP2002218949 A JP 2002218949A JP 2004063226 A JP2004063226 A JP 2004063226A
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side electrode
sheet
molded body
fuel
intermediate layer
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Masahiro Sato
佐藤　政宏
Masahito Nishihara
西原　雅人
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Kyocera Corp
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Kyocera Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery cell improving electric generation characteristics, its manufacturing method and a fuel cell. <P>SOLUTION: At one side of a solid electrolyte 33b, an oxygen side electrode 33c is provided and at the other side, a fuel side electrode 33a is provided. A first and second intermediate layers 33ab, 33bc are formed between the solid electrolyte 33b and the fuel side electrode 33a, and between the solid electrolyte 33b and the oxygen side electrode 33c, respectively. Each thickness dispersion of the first and second intermediate layers 33ab, 33bc is less than 5μm. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料電池セル及びその製法並びに燃料電池に関するものである。
【０００２】
【従来技術】
次世代エネルギーとして、近年、燃料電池セルのセルスタックを収納容器内に収容した燃料電池が種々提案されている。
【０００３】
図４は、従来の固体電解質型燃料電池のセルスタックを示すもので、このセルスタックは、複数の燃料電池セル１（１ａ、１ｂ）を集合させ、一方の燃料電池セル１ａと他方の燃料電池セル１ｂとの間に金属フェルトからなる集電部材５を介在させ、一方の燃料電池セル１ａの燃料側電極７と他方の燃料電池セル１ｂの酸素側電極１１とを電気的に接続して構成されていた。
【０００４】
燃料電池セル１（１ａ、１ｂ）は、円筒状の金属からなる燃料側電極７の外周面に、固体電解質９、導電性セラミックスからなる酸素側電極１１を順次設けて構成されており、固体電解質９、酸素側電極１１から露出した燃料側電極７には、酸素側電極１１に接続しないようにインターコネクタ１３が設けられ、燃料側電極１１と電気的に接続している。
【０００５】
このインターコネクタ１３は、燃料側電極７の内部を流れる燃料ガスと、酸素側電極１１の外側を流れる酸素含有ガスとを確実に遮断するため、また、燃料ガス及び酸素含有ガスで変質しにくい緻密な導電性セラミックスが用いられている。
【０００６】
一方の燃料電池セル１ａと他方の燃料電池セル１ｂとの電気的接続は、一方の燃料電極１ａの燃料側電極７を、該燃料側電極７に設けられたインターコネクタ１３、集電部材５を介して、他方の燃料電池セル１ｂの酸素側電極１１に接続することにより行われていた。
【０００７】
燃料電池は、上記セルスタックを収納容器内に収容して構成され、燃料側電極７内部に燃料（水素）を流し、酸素側電極１１に空気（酸素）を流して６００〜１０００℃で発電される。
【０００８】
そして、従来、燃料電池セルは、量産性の点から、燃料側電極７、固体電解質９を同時焼成し、固体電解質９の表面に酸素側電極１１を焼き付けて構成されていた。このような燃料電池セルでは、同時焼成時に燃料側電極の構成元素が固体電解質９に拡散することを防止するため、また実質的な電極としての機能を果たすため、燃料側電極７と固体電解質９との間に第１中間層を形成し、酸素側電極１１の構成元素の固体電解質９への拡散を防止するため、また実質的な電極としての機能を果たすため、固体電解質９と酸素側電極１１との間に第２中間層を形成して構成されていた。
【０００９】
【発明が解決しようとする課題】
しかしながら、上記した燃料電池セル１では、中間層形成材料を含有するスラリー中に浸漬したり、スラリーを筆等で塗布したりして（以下総称してスラリーを塗布するという）、中間層を形成していたため、一つの燃料電池セルであっても、部分的に中間層の膜厚の厚い部分や薄い部分が形成されたり、また、燃料電池セル毎に中間層の厚みが異なって厚みバラツキが生じ、これにより、厚みが薄い部分から構成元素が固体電解質に拡散し、固体電解質と中間層との間に絶縁層が形成され、発電量がバラツキ、燃料電池セルの本来の発電量を得ることができないという問題があった。
【００１０】
即ち、スラリー塗布法では、中間層の厚みにバラツキが発生し、中間層の厚みが薄い部分が存在する場合には、この部分から燃料側電極、酸素側電極から構成元素が拡散し、固体電解質に拡散して特性が劣化し、燃料電池セルの発電特性が低下するという問題があった。
【００１１】
一方、中間層の厚みが厚い部分が存在する場合には、この中間層が抵抗層となり、電極における導電性が低下し、燃料電池セルの発電特性が低下するという問題があった。
【００１２】
本発明は、発電特性を向上できる燃料電池セル及びその製法並びに燃料電池を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明の燃料電池セルは、固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなり、該第１、第２中間層の厚みバラツキがそれぞれ５μｍ以下であることを特徴とする。
【００１４】
このような燃料電池セルでは、固体電解質と燃料側電極との間、及び固体電解質と酸素側電極との間に第１、第２中間層が形成されているため、燃料側電極、酸素側電極の構成元素が固体電解質中に拡散することを抑制でき、固体電解質の特性劣化を防止することができる。
【００１５】
また、燃料電池セルにおける中間層の厚みバラツキが５μｍ以下であるため、中間層の厚みがほぼ一定であり、薄い部分が存在しないので、燃料側電極、酸素側電極の構成元素の固体電解質中への拡散を十分抑制できるとともに、中間層の厚みが極端に厚くなる部分もないため、中間層が抵抗体として機能する部分を無くすことができ、燃料電池セルの発電量を向上できる。
【００１６】
また、本発明の燃料電池セルの製法は、固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体を順次積層してシート状積層体を作製する工程と、該シート状積層体のシート状第１中間層成形体側を燃料側電極成形体表面に、又は前記シート状積層体のシート状第２中間層成形体側を酸素側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする。
【００１７】
この製法では、焼成後、第２中間層又は第１中間層の表面に、酸素側電極材料又は燃料側電極材料を含有する成形体を作製し、熱処理して酸素側電極又は燃料側電極を作製する工程を具備することが望ましい。
【００１８】
このような製法では、シート状の成形体を用いて第１、第２中間層を形成するため、第１、第２中間層の厚みを一定の厚みバラツキに容易に制御することができるとともに、第１、第２中間層を形成するためのシート状の成形体を、所定の厚みを有するシート状固体電解質成形体に積層してシート状積層体を作製し、このシート状積層体を、燃料側電極成形体表面又は酸素側電極成形体表面に積層するため、シート状第１中間層成形体とシート状第２中間層成形体の厚みを薄くしても、取り扱いが容易であり、薄いシート状第１中間層成形体、シート状第２中間層成形体を、燃料側電極成形体表面又は酸素側電極成形体表面に容易にかつ確実に積層することができる。
【００１９】
また、本発明の燃料電池セルの製法は、固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体と、シート状酸素側電極成形体とを順次積層してシート状成形体を作製する工程と、該シート状積層体のシート状第１中間層成形体側を燃料側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする。
【００２０】
また、固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状燃料側電極成形体と、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体とを順次積層してシート状成形体を作製する工程と、該シート状積層体のシート状第２中間層成形体側を酸素側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする。
【００２１】
このような製法では、第１、第２中間層の厚みを一定の厚みバラツキに容易に制御することができるとともに、シート状第１中間層成形体とシート状第２中間層成形体の厚みを薄くしても、取り扱いが容易であり、薄いシート状第１中間層成形体、シート状第２中間層成形体を、燃料側電極成形体表面又は酸素側電極成形体表面に容易にかつ確実に積層することができ、さらに、この発明では、燃料側電極、第１中間層、固体電解質、第２中間層、酸素側電極を同時焼成により一括して作製することができる。
【００２２】
また、本発明の燃料電池セルの製法は、シート状積層体が、熱圧着若しくは冷間静水圧プレスにて作製されることを特徴とする。このような製法を採用することにより、シート状第１中間層成形体、シート状第２中間層成形体と、シート状固体電解質成形体との接合強度を向上でき、焼成後における剥離を抑制できる。
【００２３】
また、本発明の燃料電池は、上記した燃料電池セルを複数収納容器内に収納してなるものである。このような燃料電池では、発電量の多い燃料電池セルを用いて構成されるため、発電量を大幅に向上できる。
【００２４】
【発明の実施の形態】
図１は本発明の燃料電池セルの横断面を示すもので、図１の燃料電池セル３３は断面が扁平状で、全体的に見て楕円柱状であり、その内部には複数の燃料ガス通路３４が形成されている。この燃料電池セル３３は、断面が扁平状で、全体的に見て楕円柱状の多孔質な金属を主成分とする燃料側電極（内側電極）３３ａの外面に、緻密質な固体電解質３３ｂ、多孔質な導電性セラミックスからなる酸素側電極（外側電極）３３ｃを順次積層し、酸素側電極３３ｃと反対側の燃料側電極３３ａの外面にインターコネクタ３３ｄを形成して構成されており、燃料側電極３３ａが支持体となっている。
【００２５】
即ち、燃料電池セル３３は、断面形状が、幅方向両端に設けられた弧状部Ａと、これらの弧状部Ａを連結する一対の平坦部Ｂとから構成されており、一対の平坦部Ｂは平坦であり、ほぼ平行に形成されている。これらの一対の平坦部Ｂは、燃料側電極３３ａの平坦部にインターコネクタ３３ｄ、又は固体電解質３３ｂ、酸素側電極３３ｃを形成して構成されている。
【００２６】
燃料側電極３３ａは、Ｎｉ、Ｃｏ、Ｔｉ、Ｒｕのうちいずれか一種の金属又は金属酸化物、もしくはこれらの合金又は合金酸化物を主成分とするものであり、これら以外に、外面の固体電解質３３ｂへの接合強度を向上し、固体電解質３３ｂの熱膨張係数に近似させるため、例えば固体電解質材料を含有している。金属又は金属酸化物としては、コストの観点からＮｉ又はＮｉＯが望ましい。
【００２７】
この燃料側電極３３ａの内部には、燃料側電極３３ａの軸長方向に複数の燃料ガス通路３４が形成されている。尚、燃料側電極３３ａは楕円柱状である必要はなく、円筒状であっても良く、四角筒状であっても良い。
【００２８】
この燃料側電極３３ａの外面に設けられた固体電解質３３ｂは、３〜１５モル％のＹ、希土類元素を含有した部分安定化あるいは安定化ＺｒＯ２からなる緻密質なセラミックスが用いられている。この固体電解質３３ｂの厚みは、ガス透過を防止するという点から１０〜１００μｍであることが望ましい。
【００２９】
また、酸素側電極３３ｃは、ＬａＦｅＯ３系材料、ＬａＣｏＯ３系材料の少なくとも一種の多孔質の導電性セラミックスから構成されている。酸素側電極３３ｃは、６００〜１０００℃程度の比較的低温での電気伝導性が高いという点からＬａＦｅＯ３系材料が望ましい。酸素側電極３３ｃの厚みは、集電性という点から３０〜１００μｍであることが望ましい。
【００３０】
燃料側電極３３ａ外面の一部には、その軸長方向に固体電解質３３ｂ及び酸素側電極３３ｃが形成されていない部分を有しており、この固体電解質３３ｂ及び酸素側電極３３ｃから露出した燃料側電極３３ａの外面には、導電性セラミックスからなるインターコネクタ３３ｄが形成されている。
【００３１】
このインターコネクタ３３ｄの厚みは、緻密性と電気抵抗という点から３０〜２００μｍであることが望ましい。インターコネクタ３３ｄは、ＬａＣｒＯ３系材料の導電性セラミックスから構成されている。インターコネクタ３３ｄは、燃料側電極３３ａの内外の燃料ガス、酸素含有ガスの漏出を防止するため緻密質とされており、また、インターコネクタ３３ｄは、その内外面が燃料ガス、酸素含有ガスと接触するため、耐還元性、耐酸化性を有している。
【００３２】
このインターコネクタ３３ｄと固体電解質３３ｂとの間には、シール性を向上すべく接合層を介在させても良い。
【００３３】
そして、本発明の燃料電池セルは、図２に示すように、固体電解質３３ｂと燃料側電極３３ａとの間に、燃料側電極３３ａの構成元素が固体電解質３３ｂに拡散することを防止するための第１中間層３３ａｂが形成され、固体電解質３３ｂと酸素側電極３３ｃとの間に、酸素側電極３３ｃの構成元素が固体電解質３３ｂに拡散することを防止するための第２中間層３３ｂｃが形成されており、これらの第１、第２中間層３３ａｂ、３３ｂｃの厚みバラツキはそれぞれ５μｍ以下とされている。
【００３４】
尚、第１中間層３３ａｂは、インターコネクタ３３ｄの形成位置を除いて、燃料側電極３３ａの全面に形成され、第２中間層３３ｂｃは、酸素側電極３３ｃが形成された部分のみ形成されている。第１、第２中間層３３ａｂ、３３ｂｃの厚みバラツキは、図１の下側の平坦部Ｂにおいて幅方向に所定間隔を置いた３点で測定し、その最大厚みと最小厚みの差とした。
【００３５】
第１中間層３３ａｂは、例えばＹを含有するＺｒＯ２と、Ｎｉ又はＮｉＯとから構成されており、厚みが１０〜５０μｍ、特に１０〜３０μｍとされており、第２中間層３３ｂｃは、Ｓｍ２Ｏ３とＣｅＯ２とから構成されており、厚みが１〜２０μｍ、特に１〜１０μｍとされている。
【００３６】
第１、第２中間層３３ａｂ、３３ｂｃの厚みバラツキを５μｍ以下としたのは、厚みバラツキが５μｍよりも大きいと、第１、第２中間層３３ａｂ、３３ｂｃの厚みが極端に厚い部分と、極端に薄い部分が形成されることになり、薄い部分では、電極材料の固体電解質３３ｂへの拡散を十分に抑制することができず、一方、厚い部分では、これらの中間層３３ａｂ、３３ｂｃが抵抗層となり、燃料電池セルの発電量が小さくなるからである。中間層３３ａｂ、３３ｂｃの厚みバラツキは、特に３μｍ以下が望ましい。
【００３７】
以上のような燃料電池セルの製造方法について説明する。先ず、例えば、ＮｉＯ粉末と、Ｙを８モル％含有したＺｒＯ２（ＹＳＺ）粉末と、有機バインダーと、溶媒とを混合した燃料側電極材料を押出成形して、楕円柱状の燃料側電極成形体を作製し、これを乾燥する。
【００３８】
次に、例えば、ＹＳＺ粉末と、有機バインダーと、溶媒とを混合した、固体電解質材料を用いてシート状成形体を作製する。
【００３９】
また、第１、第２中間層３３ａｂ、３３ｂｃを形成するシート状成形体を作製する。例えば、Ｙを含有するＺｒＯ２（ＹＳＺ）粉末と、Ｎｉ又はＮｉＯ粉末と、有機バインダーと、溶媒とを混合し、これを用いてシート第１中間層成形体を作製する。また、Ｓｍ２Ｏ３粉末と、ＣｅＯ２粉末と、有機バインダーと、溶媒とを混合し、これを用いてシート状第２中間層成形体を作製する。
【００４０】
この後、図３に示すように、シート状第１中間層成形体１３３ａｂと、シート状固体電解質成形体１３３ｂと、シート状第２中間層成形体１３３ｂｃを順次積層し、熱圧着又は冷間静水圧プレスにてシート状積層体１３５を作製する。この熱圧着又は冷間静水圧プレスにより、シート状第１中間層成形体１３３ａｂ、シート状固体電解質成形体１３３ｂ、シート状第２中間層成形体１３３ｂｃの３層間の接合強度を向上できる。
【００４１】
このシート状積層体１３５のシート状第１中間層成形体１３３ａｂ側を燃料側電極成形体１３３ａ表面に、その両端間が燃料側電極成形体１３３ａの平坦部で所定間隔をおいて離間するように巻き付け、乾燥し、積層成形体を作製する。
【００４２】
本発明では、シート状第１中間層成形体１３３ａｂと、シート状第２中間層成形体１３３ｂｃを用いて第１、第２中間層３３ａｂ、３３ｂｃが形成されるため、場所による厚みバラツキを殆どなくすことができる。
【００４３】
この後、例えば、ＬａＣｒＯ３系材料と、有機バインダーと、溶媒とを混合した、インターコネクタ材料を用いてシート状成形体を作製し、このシート状成形体を、露出した燃料側電極成形体１３３ａの外面に積層し、燃料側電極成形体１３３ａに、中間層成形体１３３ａｂ、１３３ｂｃ、シート状固体電解質成形体１３３ｂ、インターコネクタ３３ｄのシート状成形体が積層された積層成形体を作製する。
【００４４】
次に、積層成形体を脱バインダ処理し、酸素含有雰囲気中で１３００〜１６００℃で同時焼成する。焼成後、例えばＬａＦｅＯ３系材料からなる酸素側電極材料を含有するスラリーを作製し、これを浸漬塗布法により第２中間層３３ｂｃの表面に酸素側電極の成形体を形成する。尚、筆等によりスラリを塗布してもよく、また、スラリーを噴霧装置（スプレードライ）により噴霧し、落下中に乾燥させ、堆積させ、第２中間層の表面に酸素側電極を形成する成形体を作製しても良い。次に、１１００〜１３００℃の温度で大気中で加熱処理することにより、第２中間層３３ｂｃの表面に酸素側電極を作製する。
【００４５】
尚、本発明は上記形態に限定されるものではなく、発明の要旨を変更しない範囲で種々の変更が可能である。例えば、上記例では、燃料側電極の表面に固体電解質、インターコネクタの成形体が積層された積層成形体を焼成した後、酸素側電極を形成した例について説明したが、例えば、燃料側電極に固体電解質を形成した後、この固体電解質表面に酸素側電極を形成し、その後インターコネクタを形成しても良い。
【００４６】
また、上記例では、燃料側電極を支持体としたが、酸素側電極を支持体としても良い。この場合には、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体を順次積層してシート状積層体を作製し、このシート状積層体のシート状第２中間層成形体側を支持体となる酸素側電極成形体表面に積層して積層成形体を作製し、これを焼成し、この後、第１中間層上に燃料電極を形成することになる。
【００４７】
さらに、上記した例では、第２中間層の表面に酸素側電極を熱処理して形成した例について説明したが、本発明では、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体、シート状酸素側電極成形体を順次積層してシート状積層体を作製し、このシート状積層体を支持体となる燃料側電極成形体表面に積層して積層成形体を作製し、これを焼成して燃料電池セルを作製することもできる。この場合には一括焼成により燃料電池セルを作製することができ、工程を削減できる。
【００４８】
また、シート状燃料側電極成形体と、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体を順次積層してシート状積層体を作製し、このシート状積層体のシート状第２中間層成形体側を支持体となる酸素側電極成形体表面に積層して積層成形体を作製し、これを焼成して燃料電池セルを作製することもできる。この場合にも一括焼成により燃料電池セルを作製することができるため、工程を削減できる。
【００４９】
さらに、上記例では、楕円柱型の燃料電池セルについて説明したが、本発明では燃料電池セルの形状は限定されるものではなく、例えば円筒状の燃料電池セルでも良い。さらに、上記例では、インターコネクタが外面に露出した燃料電池セルについて説明したが、インターコネクタを具備しない、即ち、燃料側電極の外面を取り囲むように固体電解質を形成し、この固体電解質の外面を取り囲むようにして酸素側電極を形成した燃料電池セルであっても良い。
【００５０】
本発明の燃料電池は、図１、２の燃料電池セルが、収納容器内に収容されて燃料電池が構成されている。
【００５１】
【実施例】
先ず、平均粒径０．５μｍのＮｉＯ粉末と、平均粒径０．５μｍのＹを８モル％含有したＺｒＯ２（ＹＳＺ）粉末と、ポアー剤、ＰＶＡからなる有機バインダーと、水からなる溶媒とを混合した燃料側電極材料を押出成形して、楕円柱状の燃料側電極成形体を作製し、これを乾燥した。
【００５２】
次に、上記ＹＳＺ粉末と、アクリル樹脂からなる有機バインダーと、トルエンからなる溶媒とを混合した固体電解質材料を用いて平均厚み４５μｍのシート状成形体を作製した。
【００５３】
また、平均粒径１μｍのＹＳＺ粉末と、平均粒径０．５μｍのＮｉ粉末と、有機バインダーと、溶媒とを混合し、これを用いて平均厚み１５μｍ、４０μｍのシート状第１中間層成形体を作製した。さらに、平均粒径１μｍのＳｍ２Ｏ３粉末と、平均粒径１μｍのＣｅＯ２粉末と、有機バインダーと、溶媒とを混合し、これを用いて平均厚み１０μｍ、２０μｍのシート状第２中間層成形体を作製した。
【００５４】
この後、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体を順次積層し、このシート状積層体を冷間静水圧プレスした。
【００５５】
このシート状積層体のシート状第１中間層成形体側を燃料側電極成形体表面に、その両端間が燃料側電極成形体の平坦部で所定間隔をおいて離間するように巻き付け、乾燥した。
【００５６】
この後、ＬａＣｒＯ３系材料と、有機バインダーと、溶媒とを混合した、インターコネクタ材料を用いてシート状成形体を作製し、このシート状成形体を、露出した燃料側電極成形体の外面に積層し、燃料側電極成形体に、中間層成形体、固体電解質のシート状成形体、インターコネクタのシート状成形体が積層された積層成形体を作製した。
【００５７】
次に、積層成形体を脱バインダ処理し、大気中で１５００℃で同時焼成した。焼成後、ＬａＦｅＯ３系材料からなる酸素側電極材料を含有するスラリーを作製し、これを浸漬塗布法により第２中間層の表面に酸素側電極を形成する成形体を作製した。次に、大気中で１１５０℃で加熱処理することにより、第２中間層の表面に酸素側電極を作製し、図１に示した燃料電池セルを作製した。
【００５８】
作製した燃料電池セルの寸法は、弧状部Ａ間の距離で示される幅２６ｍｍ、平坦部Ｂ間で示される厚み３．２ｍｍ、長さ１８５ｍｍであった。また、固体電解質の厚みは３０μｍ、酸素側電極の厚みが５０μｍであった。
【００５９】
これらの燃料電池セルの出力密度を、８５０℃の温度で０．７Ｖを印加して測定し、表１に記載した。また、第１、第２中間層の厚みバラツキを、図１での下側の平坦部Ｂにおいて幅方向に所定間隔を置いた３点で顕微鏡で測定し、その最大厚みと最小厚みの差を算出し、第１、第２中間層の厚みバラツキとしてそれぞれ表１に記載した。厚みの測定個所は、幅方向の中央部と、弧状部Ａ端から５ｍｍの部分を測定した。
【００６０】
また、燃料側電極成形体上に、上記したスラリーを厚み１５μｍとなるようにスクリーン印刷して第１中間層成形体を形成し、この表面に、上記した固体電解質のシート状成形体を積層した後、仮焼し、固体電解質表面に、上記したスラリーを厚み１０μｍとなるようにスクリーン印刷して第２中間層成形体を形成し、上記したインターコネクタのシート状成形体を積層し、焼成して比較例の燃料電池セルを作製し、燃料電池セルの出力密度と第１、第２中間層の厚みバラツキを上記と同様にして測定し、表１の試料Ｎｏ．３に記載した。
【００６１】
【表１】

Figure 2004063226
【００６２】
この表１から、本発明の燃料電池セルでは厚みバラツキが５μｍ以下であり、出力密度が０．４Ｗ／ｃｍ２以上であるのに対して、比較例の試料Ｎｏ．３では、厚みバラツキが７μｍ以上であり、出力密度が０．２Ｗ／ｃｍ２と低かった。
【００６３】
比較例の試料Ｎｏ．３において、第１中間層近傍の固体電解質及び第２中間層近傍の固体電解質をＥＰＭＡ（元素拡散分析）により観測したところ、第１中間層近傍の固体電解質ではＹ、Ｎｉが、第２中間層近傍の固体電解質ではＬａ、Ｆｅがそれぞれに拡散していた。一方、本発明の試料では、第１中間層近傍の固体電解質及び第２中間層近傍の固体電解質には、燃料側電極、酸素側電極材料は拡散していなかった。
【００６４】
【発明の効果】
本発明の燃料電池セルでは、第１、第２中間層の厚みバラツキが５μｍ以下であるため、中間層の厚みがほぼ一定であり、薄い部分が存在しないので、燃料側電極、酸素側電極の構成元素の固体電解質中への拡散を十分抑制できるとともに、中間層の厚みが極端に厚くなる部分もないため、中間層が抵抗体として機能する部分を無くすことができ、燃料電池セルの発電量を向上できる。
【図面の簡単な説明】
【図１】本発明の燃料電池セルを示す横断面図である。
【図２】図１の一部を拡大して示す横断面図である。
【図３】シート状積層体を燃料側電極成形体表面に巻き付ける状態を示す断面図である。
【図４】インターコネクタが形成された円筒状の燃料電池セルを複数接続した従来のセルスタックを示す横断面図である。
【符号の説明】
３３・・・燃料電池セル
３３ａ・・・燃料側電極
３３ｂ・・・固体電解質
３３ｃ・・・酸素側電極
３３ａｂ・・・第１中間層
３３ｂｃ・・・第２中間層
１３３ａ・・・燃料側電極成形体
１３３ｂ・・・シート状固体電解質成形体
１３３ａｂ・・・シート状第１中間層成形体
１３３ｂｃ・・・シート状第２中間層成形体
１３５・・・シート状積層体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell, a method for producing the same, and a fuel cell.
[0002]
[Prior art]
In recent years, as a next-generation energy, various fuel cells have been proposed in which a cell stack of fuel cells is housed in a housing.
[0003]
FIG. 4 shows a cell stack of a conventional solid oxide fuel cell. In this cell stack, a plurality of fuel cells 1 (1a, 1b) are assembled, and one fuel cell 1a and the other fuel cell 1a. A current collecting member 5 made of metal felt is interposed between the fuel cell 1b and the fuel-side electrode 7 of one fuel cell 1a and the oxygen-side electrode 11 of the other fuel cell 1b are electrically connected. It had been.
[0004]
The fuel cell 1 (1a, 1b) is configured by sequentially providing a solid electrolyte 9 and an oxygen electrode 11 made of conductive ceramic on an outer peripheral surface of a fuel electrode 7 made of a cylindrical metal. 9, an interconnector 13 is provided on the fuel electrode 7 exposed from the oxygen electrode 11 so as not to be connected to the oxygen electrode 11, and is electrically connected to the fuel electrode 11.
[0005]
This interconnector 13 is used to reliably shut off the fuel gas flowing inside the fuel-side electrode 7 and the oxygen-containing gas flowing outside the oxygen-side electrode 11, Conductive ceramics are used.
[0006]
The electrical connection between one fuel cell 1a and the other fuel cell 1b is performed by connecting the fuel-side electrode 7 of the one fuel electrode 1a to the interconnector 13 and the current collecting member 5 provided on the fuel-side electrode 7. Through the connection to the oxygen-side electrode 11 of the other fuel cell 1b.
[0007]
The fuel cell is configured by housing the above cell stack in a storage container, and flows fuel (hydrogen) inside the fuel side electrode 7 and air (oxygen) through the oxygen side electrode 11 to generate power at 600 to 1000 ° C. You.
[0008]
Conventionally, the fuel cell has been configured by simultaneously firing the fuel-side electrode 7 and the solid electrolyte 9 and baking the oxygen-side electrode 11 on the surface of the solid electrolyte 9 from the viewpoint of mass productivity. In such a fuel cell, in order to prevent the constituent elements of the fuel-side electrode from diffusing into the solid electrolyte 9 at the same time as firing, and to substantially function as an electrode, the fuel-side electrode 7 and the solid electrolyte 9 Between the solid electrolyte 9 and the oxygen-side electrode 11 to prevent the constituent elements of the oxygen-side electrode 11 from diffusing into the solid electrolyte 9 and to function as a substantial electrode. 11 and a second intermediate layer was formed.
[0009]
[Problems to be solved by the invention]
However, in the above-described fuel cell 1, the intermediate layer is formed by dipping in a slurry containing the intermediate layer forming material or by applying the slurry with a brush or the like (hereinafter collectively referred to as slurry application). Therefore, even with a single fuel cell, a thick part or a thin part of the intermediate layer is partially formed, or the thickness of the intermediate layer differs for each fuel cell, resulting in a thickness variation. As a result, the constituent elements diffuse from the thin portion into the solid electrolyte, an insulating layer is formed between the solid electrolyte and the intermediate layer, the power generation varies, and the original power generation of the fuel cell is obtained. There was a problem that can not be.
[0010]
That is, in the slurry coating method, the thickness of the intermediate layer varies, and when there is a portion where the thickness of the intermediate layer is thin, constituent elements are diffused from this portion from the fuel electrode and the oxygen electrode, and the solid electrolyte is dispersed. And the characteristics are deteriorated, and the power generation characteristics of the fuel cell are degraded.
[0011]
On the other hand, when there is a portion where the thickness of the intermediate layer is large, there is a problem that the intermediate layer becomes a resistance layer, the conductivity of the electrode decreases, and the power generation characteristics of the fuel cell deteriorate.
[0012]
An object of the present invention is to provide a fuel cell, a method for producing the same, and a fuel cell capable of improving power generation characteristics.
[0013]
[Means for Solving the Problems]
The fuel cell of the present invention is provided with an oxygen-side electrode on one side of a solid electrolyte and a fuel-side electrode on the other side, between the solid electrolyte and the fuel-side electrode, and between the solid electrolyte and the oxygen-side electrode. A first and a second intermediate layer are formed between the first and second intermediate layers, respectively, and the first and second intermediate layers each have a thickness variation of 5 μm or less.
[0014]
In such a fuel cell, since the first and second intermediate layers are formed between the solid electrolyte and the fuel-side electrode and between the solid electrolyte and the oxygen-side electrode, the fuel-side electrode and the oxygen-side electrode Can be suppressed from diffusing into the solid electrolyte, and characteristic deterioration of the solid electrolyte can be prevented.
[0015]
In addition, since the thickness variation of the intermediate layer in the fuel cell is 5 μm or less, the thickness of the intermediate layer is almost constant, and there is no thin portion. Diffusion can be sufficiently suppressed, and since there is no portion where the thickness of the intermediate layer is extremely large, a portion where the intermediate layer functions as a resistor can be eliminated, and the power generation amount of the fuel cell unit can be improved.
[0016]
Further, the method of manufacturing a fuel cell according to the present invention includes providing an oxygen-side electrode on one side of the solid electrolyte and a fuel-side electrode on the other side, between the solid electrolyte and the fuel-side electrode, and between the solid electrolyte and the solid electrolyte. A method for producing a fuel cell comprising a first intermediate layer and a second intermediate layer formed between an oxygen-side electrode and a sheet-shaped first intermediate layer molded article, a sheet-shaped solid electrolyte molded article, (2) a step of sequentially laminating the intermediate layer molded bodies to form a sheet-shaped laminated body, and a step of placing the sheet-shaped first intermediate layer molded body side of the sheet-shaped laminated body on the surface of the fuel-side electrode molded body, or It is characterized by comprising a step of laminating the sheet-like second intermediate layer molded body side on the surface of the oxygen-side electrode molded body to produce a laminated molded body, and a step of firing the laminated molded body.
[0017]
In this manufacturing method, after firing, a molded body containing the oxygen-side electrode material or the fuel-side electrode material is produced on the surface of the second intermediate layer or the first intermediate layer, and heat-treated to produce the oxygen-side electrode or the fuel-side electrode. It is desirable to include a step of performing the following.
[0018]
In such a manufacturing method, since the first and second intermediate layers are formed using the sheet-like molded body, the thickness of the first and second intermediate layers can be easily controlled to have a constant thickness variation, and A sheet-like molded body for forming the first and second intermediate layers is laminated on a sheet-like solid electrolyte molded body having a predetermined thickness to produce a sheet-like laminate, and this sheet-like laminate is used as a fuel. Even when the thickness of the sheet-like first intermediate layer molded body and the sheet-like second intermediate layer molded body is reduced, since they are laminated on the surface of the side electrode molded body or the surface of the oxygen-side electrode molded body, handling is easy and the thin sheet is formed. The shaped first intermediate layer molded product and the sheet-shaped second intermediate layer molded product can be easily and reliably laminated on the surface of the fuel-side electrode molded product or the surface of the oxygen-side electrode molded product.
[0019]
Further, the method of manufacturing a fuel cell according to the present invention includes providing an oxygen-side electrode on one side of the solid electrolyte and a fuel-side electrode on the other side, between the solid electrolyte and the fuel-side electrode, and between the solid electrolyte and the solid electrolyte. A method for producing a fuel cell comprising a first intermediate layer and a second intermediate layer formed between an oxygen-side electrode and a sheet-shaped first intermediate layer molded article, a sheet-shaped solid electrolyte molded article, (2) a step of sequentially laminating the intermediate layer molded body and the sheet-shaped oxygen-side electrode molded body to produce a sheet-shaped molded body, and a sheet-shaped first intermediate layer molded body side of the sheet-shaped laminated body being a fuel-side electrode molded body It is characterized by comprising a step of producing a laminated molded body by laminating on a surface, and a step of firing the laminated molded body.
[0020]
Also, an oxygen-side electrode is provided on one side of the solid electrolyte, and a fuel-side electrode is provided on the other side, and between the solid electrolyte and the fuel-side electrode, and between the solid electrolyte and the oxygen-side electrode, A method for producing a fuel cell, comprising forming a second intermediate layer, comprising: a sheet-shaped fuel-side electrode molded body; a sheet-shaped first intermediate layer molded body; a sheet-shaped solid electrolyte molded body; A step of sequentially laminating the intermediate layer molded body to form a sheet-shaped molded body, and laminating a sheet-shaped second intermediate layer molded body side of the sheet-shaped laminated body on the surface of the oxygen-side electrode molded body to produce a laminated molded body And firing the laminated molded body.
[0021]
In such a manufacturing method, the thickness of the first and second intermediate layers can be easily controlled to have a constant thickness variation, and the thickness of the sheet-like first intermediate layer molded article and the sheet-like second intermediate layer molded article can be reduced. Even if it is thin, it is easy to handle, and the thin sheet-like first intermediate layer molded product and the sheet-like second intermediate layer molded product can be easily and reliably applied to the surface of the fuel-side electrode molded product or the surface of the oxygen-side electrode molded product. The fuel-side electrode, the first intermediate layer, the solid electrolyte, the second intermediate layer, and the oxygen-side electrode can be collectively manufactured by simultaneous firing.
[0022]
Further, the method for producing a fuel cell of the present invention is characterized in that the sheet-like laminate is produced by thermocompression bonding or cold isostatic pressing. By employing such a manufacturing method, the bonding strength between the sheet-like first intermediate layer molded body, the sheet-like second intermediate layer molded body, and the sheet-like solid electrolyte molded body can be improved, and peeling after firing can be suppressed. .
[0023]
In addition, the fuel cell of the present invention is one in which the above-described fuel cells are housed in a plurality of storage containers. Since such a fuel cell is configured by using a fuel cell having a large amount of power generation, the amount of power generation can be greatly improved.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a cross section of a fuel cell unit according to the present invention. The fuel cell unit 33 shown in FIG. 1 has a flat cross section, an elliptical column shape as a whole, and a plurality of fuel gas passages therein. 34 are formed. This fuel cell 33 has a flat solid electrolyte 33b on the outer surface of a fuel-side electrode (inner electrode) 33a mainly composed of a porous metal having a flat cross section and an elliptic column shape as a whole. An oxygen-side electrode (outside electrode) 33c made of high quality conductive ceramics is sequentially laminated, and an interconnector 33d is formed on the outer surface of the fuel-side electrode 33a opposite to the oxygen-side electrode 33c. 33a is a support.
[0025]
That is, the fuel cell 33 has a cross-sectional shape including an arc-shaped portion A provided at both ends in the width direction and a pair of flat portions B connecting these arc-shaped portions A. It is flat and formed substantially parallel. The pair of flat portions B are formed by forming an interconnector 33d, a solid electrolyte 33b, and an oxygen-side electrode 33c on the flat portion of the fuel-side electrode 33a.
[0026]
The fuel-side electrode 33a is mainly composed of any one of Ni, Co, Ti, and Ru, or a metal oxide or an alloy or alloy oxide thereof. For example, a solid electrolyte material is included in order to improve the bonding strength to the solid electrolyte 33b and approximate the thermal expansion coefficient of the solid electrolyte 33b. As the metal or metal oxide, Ni or NiO is desirable from the viewpoint of cost.
[0027]
Inside the fuel electrode 33a, a plurality of fuel gas passages 34 are formed in the axial direction of the fuel electrode 33a. Note that the fuel-side electrode 33a does not need to have an elliptical column shape, and may be a cylindrical shape or a square tube shape.
[0028]
As the solid electrolyte 33b provided on the outer surface of the fuel-side electrode 33a, a dense ceramic made of partially stabilized or stabilized ZrO 2 containing 3 to 15 mol% of Y and a rare earth element is used. The thickness of the solid electrolyte 33b is desirably 10 to 100 μm from the viewpoint of preventing gas permeation.
[0029]
The oxygen-side electrode 33c is made of at least one kind of porous conductive ceramic of a LaFeO 3 material or a LaCoO 3 material. The oxygen-side electrode 33c is preferably made of a LaFeO 3 -based material because of its high electrical conductivity at a relatively low temperature of about 600 to 1000 ° C. The thickness of the oxygen-side electrode 33c is desirably 30 to 100 μm from the viewpoint of current collection.
[0030]
A part of the outer surface of the fuel-side electrode 33a has a portion in which the solid electrolyte 33b and the oxygen-side electrode 33c are not formed in the axial direction, and the fuel-side electrode 33b and the fuel-side electrode exposed from the oxygen-side electrode 33c are formed. An interconnector 33d made of conductive ceramic is formed on the outer surface of the electrode 33a.
[0031]
The thickness of the interconnector 33d is desirably 30 to 200 μm from the viewpoint of denseness and electric resistance. Interconnector 33d is composed of a conductive ceramic of LaCrO 3 system material. The interconnector 33d is made dense to prevent leakage of the fuel gas and oxygen-containing gas inside and outside the fuel-side electrode 33a, and the interconnector 33d has its inner and outer surfaces in contact with the fuel gas and oxygen-containing gas. Therefore, it has reduction resistance and oxidation resistance.
[0032]
A bonding layer may be interposed between the interconnector 33d and the solid electrolyte 33b in order to improve the sealing property.
[0033]
As shown in FIG. 2, the fuel cell of the present invention is provided between the solid electrolyte 33b and the fuel electrode 33a to prevent the constituent elements of the fuel electrode 33a from diffusing into the solid electrolyte 33b. A first intermediate layer 33ab is formed, and a second intermediate layer 33bc is formed between the solid electrolyte 33b and the oxygen-side electrode 33c to prevent the constituent elements of the oxygen-side electrode 33c from diffusing into the solid electrolyte 33b. Each of the first and second intermediate layers 33ab and 33bc has a thickness variation of 5 μm or less.
[0034]
The first intermediate layer 33ab is formed on the entire surface of the fuel-side electrode 33a except for the position where the interconnector 33d is formed, and the second intermediate layer 33bc is formed only on the portion where the oxygen-side electrode 33c is formed. . The thickness variation of the first and second intermediate layers 33ab and 33bc was measured at three points at predetermined intervals in the width direction on the lower flat portion B in FIG. 1 and was defined as the difference between the maximum thickness and the minimum thickness.
[0035]
The first intermediate layer 33ab is made of, for example, ZrO 2 containing Y and Ni or NiO, has a thickness of 10 to 50 μm, particularly 10 to 30 μm, and the second intermediate layer 33bc has a thickness of Sm 2. It is composed of O 3 and CeO 2 and has a thickness of 1 to 20 μm, particularly 1 to 10 μm.
[0036]
The reason why the thickness variation of the first and second intermediate layers 33ab and 33bc is set to 5 μm or less is that if the thickness variation is larger than 5 μm, the thickness of the first and second intermediate layers 33ab and 33bc becomes extremely thick, In the thin portion, the diffusion of the electrode material into the solid electrolyte 33b cannot be sufficiently suppressed. On the other hand, in the thick portion, the intermediate layers 33ab and 33bc are formed by the resistance layer. This is because the power generation amount of the fuel cell decreases. The thickness variation of the intermediate layers 33ab and 33bc is particularly preferably 3 μm or less.
[0037]
A method for manufacturing the above fuel cell will be described. First, for example, a fuel-side electrode material obtained by mixing NiO powder, ZrO 2 (YSZ) powder containing 8 mol% of Y, an organic binder, and a solvent is extruded to form an elliptic column-shaped fuel-side electrode molded body. Is prepared and dried.
[0038]
Next, for example, a sheet-like molded body is produced using a solid electrolyte material obtained by mixing YSZ powder, an organic binder, and a solvent.
[0039]
Further, a sheet-like molded body forming the first and second intermediate layers 33ab and 33bc is produced. For example, a ZrO 2 (YSZ) powder containing Y, Ni or NiO powder, an organic binder, and a solvent are mixed, and the mixture is used to produce a sheet first intermediate layer molded body. Further, Sm 2 O 3 powder, CeO 2 powder, an organic binder, and a solvent are mixed, and the mixture is used to produce a sheet-like second intermediate layer molded body.
[0040]
Thereafter, as shown in FIG. 3, the sheet-like first intermediate layer molded body 133ab, the sheet-like solid electrolyte molded body 133b, and the sheet-like second intermediate layer molded body 133bc are sequentially laminated, and then thermocompression-bonded or cold-statically pressed. The sheet-like laminate 135 is produced by a hydraulic press. By this thermocompression bonding or cold isostatic pressing, the bonding strength between the three layers of the sheet-like first intermediate layer molded body 133ab, the sheet-like solid electrolyte molded body 133b, and the sheet-like second intermediate layer molded body 133bc can be improved.
[0041]
The sheet-like first intermediate layer molded body 133ab side of the sheet-like laminated body 135 is disposed on the surface of the fuel-side electrode molded body 133a, and both ends thereof are separated from each other at a predetermined interval by a flat portion of the fuel-side electrode molded body 133a. It is wound and dried to produce a laminated molded body.
[0042]
In the present invention, since the first and second intermediate layers 33ab and 33bc are formed by using the sheet-like first intermediate layer molded body 133ab and the sheet-like second intermediate layer molded body 133bc, thickness variations due to locations are almost eliminated. be able to.
[0043]
Thereafter, for example, a sheet-like molded body is manufactured using an interconnector material obtained by mixing a LaCrO 3 -based material, an organic binder, and a solvent, and the sheet-like molded body is removed from the exposed fuel-side electrode molded body 133a. And an intermediate layer molded body 133ab, 133bc, a sheet-shaped solid electrolyte molded body 133b, and a sheet-shaped molded body of an interconnector 33d are laminated on the fuel-side electrode molded body 133a to produce a laminated molded body.
[0044]
Next, the laminated molded body is subjected to a binder removal treatment and simultaneously fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere. After firing, a slurry containing an oxygen-side electrode material made of, for example, a LaFeO 3 -based material is prepared, and a slurry of the oxygen-side electrode is formed on the surface of the second intermediate layer 33bc by dip coating. The slurry may be applied with a brush or the like, or the slurry may be sprayed by a spray device (spray dry), dried and deposited while falling, and formed to form an oxygen-side electrode on the surface of the second intermediate layer. A body may be made. Next, an oxygen-side electrode is formed on the surface of the second intermediate layer 33bc by performing a heat treatment in the air at a temperature of 1100 to 1300 ° C.
[0045]
Note that the present invention is not limited to the above-described embodiment, and various changes can be made without changing the gist of the present invention. For example, in the above-described example, the solid electrolyte on the surface of the fuel-side electrode, an example in which the oxygen-side electrode was formed after firing a laminated molded body in which the molded body of the interconnector was laminated was described. After forming the solid electrolyte, an oxygen-side electrode may be formed on the surface of the solid electrolyte, and then an interconnector may be formed.
[0046]
In the above example, the fuel-side electrode is used as the support, but the oxygen-side electrode may be used as the support. In this case, the sheet-like first intermediate layer molded body, the sheet-like solid electrolyte molded body, and the sheet-like second intermediate layer molded body are sequentially laminated to produce a sheet-like laminate. Laminating the sheet-like second intermediate layer molded body side on the surface of the oxygen-side electrode molded body serving as a support to produce a laminated molded body, firing it, and then forming a fuel electrode on the first intermediate layer become.
[0047]
Furthermore, in the above-described example, the example in which the oxygen-side electrode was formed by heat treatment on the surface of the second intermediate layer was described. However, in the present invention, the sheet-like first intermediate layer molded body, the sheet-like solid electrolyte molded body, The sheet-like second intermediate layer molded product and the sheet-like oxygen-side electrode molded product are sequentially laminated to produce a sheet-like laminate, and the sheet-like laminate is laminated on the surface of the fuel-side electrode molded product serving as a support. A fuel cell can also be manufactured by producing a laminated molded body and firing it. In this case, the fuel cells can be manufactured by batch firing, and the number of steps can be reduced.
[0048]
Further, a sheet-like fuel-side electrode molded body, a sheet-like first intermediate layer molded body, a sheet-like solid electrolyte molded body, and a sheet-like second intermediate layer molded body are sequentially laminated to produce a sheet-like laminate. The sheet-like second intermediate layer molded body side of the sheet-like laminate is laminated on the surface of the oxygen-side electrode molded body serving as a support to produce a laminated molded body, which is then fired to produce a fuel cell. . Also in this case, the fuel cells can be manufactured by batch firing, so that the number of steps can be reduced.
[0049]
Further, in the above-described example, the elliptic column fuel cell is described. However, in the present invention, the shape of the fuel cell is not limited, and may be, for example, a cylindrical fuel cell. Further, in the above example, the fuel cell in which the interconnector is exposed on the outer surface has been described, but the interconnector is not provided, that is, a solid electrolyte is formed so as to surround the outer surface of the fuel electrode, and the outer surface of the solid electrolyte is formed. A fuel cell in which an oxygen-side electrode is formed so as to surround it may be used.
[0050]
In the fuel cell of the present invention, the fuel cell of FIGS. 1 and 2 is housed in a housing container to constitute a fuel cell.
[0051]
【Example】
First, a NiO powder having an average particle diameter of 0.5 μm, a ZrO 2 (YSZ) powder containing 8 mol% of Y having an average particle diameter of 0.5 μm, an organic binder including a pore agent and PVA, and a solvent including water The mixture was extruded to produce a fuel-side electrode molded article having an elliptical column shape, and this was dried.
[0052]
Next, a sheet-like molded body having an average thickness of 45 μm was prepared using a solid electrolyte material obtained by mixing the YSZ powder, an organic binder composed of an acrylic resin, and a solvent composed of toluene.
[0053]
Further, a YSZ powder having an average particle size of 1 μm, a Ni powder having an average particle size of 0.5 μm, an organic binder, and a solvent are mixed, and the mixture is used to form a sheet-like first intermediate layer molded product having an average thickness of 15 μm and 40 μm. Was prepared. Further, a Sm 2 O 3 powder having an average particle diameter of 1 μm, a CeO 2 powder having an average particle diameter of 1 μm, an organic binder, and a solvent are mixed, and the mixture is used to form a sheet-like second intermediate layer having an average thickness of 10 μm and 20 μm. A molded body was produced.
[0054]
Thereafter, the sheet-like first intermediate layer molded body, the sheet-like solid electrolyte molded body, and the sheet-like second intermediate layer molded body were sequentially laminated, and the sheet-like laminated body was subjected to cold isostatic pressing.
[0055]
The sheet-like first intermediate layer molded body side of this sheet-like laminate was wound around the surface of the fuel-side electrode molded body so that both ends of the sheet-like laminated body were spaced apart from each other at a predetermined interval at a flat portion of the fuel-side electrode molded body, and dried.
[0056]
Thereafter, a sheet-like molded body is prepared using an interconnector material obtained by mixing a LaCrO 3 -based material, an organic binder, and a solvent, and the sheet-like molded body is attached to the outer surface of the exposed fuel-side electrode molded body. The laminated body was formed by laminating the intermediate-layer molded body, the solid electrolyte sheet-shaped molded body, and the interconnector sheet-shaped molded body on the fuel-side electrode molded body.
[0057]
Next, the laminated molded body was subjected to a binder removal treatment, and was simultaneously fired at 1500 ° C. in the air. After firing, a slurry containing an oxygen-side electrode material made of a LaFeO 3 -based material was prepared, and a slurry was formed by dip coating to form a molded body on which the oxygen-side electrode was formed on the surface of the second intermediate layer. Next, by performing a heat treatment at 1150 ° C. in the air, an oxygen-side electrode was formed on the surface of the second intermediate layer, and the fuel cell shown in FIG. 1 was formed.
[0058]
The dimensions of the produced fuel cell were 26 mm in width indicated by the distance between the arcuate portions A, 3.2 mm in thickness indicated by the distance between the flat portions B, and 185 mm in length. The thickness of the solid electrolyte was 30 μm, and the thickness of the oxygen-side electrode was 50 μm.
[0059]
The output densities of these fuel cells were measured at a temperature of 850 ° C. by applying 0.7 V, and are shown in Table 1. In addition, thickness variations of the first and second intermediate layers are measured with a microscope at three points at predetermined intervals in the width direction in the lower flat portion B in FIG. 1, and the difference between the maximum thickness and the minimum thickness is measured. The calculated values are shown in Table 1 as thickness variations of the first and second intermediate layers. The thickness was measured at the center in the width direction and at a portion 5 mm from the end of the arc-shaped portion A.
[0060]
Further, the slurry was screen-printed to a thickness of 15 μm on the fuel-side electrode molded body to form a first intermediate layer molded body, and the solid electrolyte sheet-shaped molded body was laminated on this surface. After that, it is calcined, and the above-mentioned slurry is screen-printed on the surface of the solid electrolyte so as to have a thickness of 10 μm to form a second intermediate layer molded body, and the above-mentioned interconnector sheet-shaped molded body is laminated and fired. The fuel cell of the comparative example was manufactured in the same manner as above, and the output density of the fuel cell and the thickness variation of the first and second intermediate layers were measured in the same manner as described above. No. 3.
[0061]
[Table 1]
Figure 2004063226
[0062]
From Table 1, it can be seen that the fuel cell of the present invention has a thickness variation of 5 μm or less and an output density of 0.4 W / cm 2 or more. In No. 3, the thickness variation was 7 μm or more, and the output density was as low as 0.2 W / cm 2 .
[0063]
Sample No. of Comparative Example 3, the solid electrolyte in the vicinity of the first intermediate layer and the solid electrolyte in the vicinity of the second intermediate layer were observed by EPMA (element diffusion analysis). In the nearby solid electrolyte, La and Fe were diffused respectively. On the other hand, in the sample of the present invention, the fuel electrode and the oxygen electrode material were not diffused into the solid electrolyte near the first intermediate layer and the solid electrolyte near the second intermediate layer.
[0064]
【The invention's effect】
In the fuel cell of the present invention, since the thickness variation of the first and second intermediate layers is 5 μm or less, the thickness of the intermediate layer is substantially constant, and there is no thin portion. The diffusion of the constituent elements into the solid electrolyte can be sufficiently suppressed, and there is no part where the thickness of the intermediate layer is extremely large. Can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a fuel cell unit of the present invention.
FIG. 2 is an enlarged cross-sectional view showing a part of FIG. 1;
FIG. 3 is a cross-sectional view showing a state in which a sheet-like laminate is wound around the surface of a fuel-side electrode molded body.
FIG. 4 is a cross-sectional view showing a conventional cell stack in which a plurality of cylindrical fuel cells having interconnectors are connected.
[Explanation of symbols]
33 ... fuel cell 33a ... fuel side electrode 33b ... solid electrolyte 33c ... oxygen side electrode 33ab ... first intermediate layer 33bc ... second intermediate layer 133a ... fuel side electrode Molded body 133b ··· sheet solid electrolyte molded body 133ab · · · sheet first intermediate layer molded body 133bc · · · sheet second intermediate layer molded body 135 · · · sheet laminated body

Claims (7)

固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなり、該第１、第２中間層の厚みバラツキがそれぞれ５μｍ以下であることを特徴とする燃料電池セル。An oxygen-side electrode is provided on one side of the solid electrolyte, and a fuel-side electrode is provided on the other side, and first and second electrodes are provided between the solid electrolyte and the fuel-side electrode and between the solid electrolyte and the oxygen-side electrode. A fuel cell comprising an intermediate layer, and wherein the first and second intermediate layers each have a thickness variation of 5 μm or less. 固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体を順次積層してシート状積層体を作製する工程と、該シート状積層体のシート状第１中間層成形体側を燃料側電極成形体表面に、又は前記シート状積層体のシート状第２中間層成形体側を酸素側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする燃料電池セルの製法。An oxygen-side electrode is provided on one side of the solid electrolyte, and a fuel-side electrode is provided on the other side, and first and second electrodes are provided between the solid electrolyte and the fuel-side electrode and between the solid electrolyte and the oxygen-side electrode. What is claimed is: 1. A method for producing a fuel cell, comprising forming an intermediate layer, wherein a sheet-like first intermediate layer molded body, a sheet-like solid electrolyte molded body, and a sheet-like second intermediate layer molded body are sequentially laminated. A step of preparing a laminate, and placing the sheet-like first intermediate layer molded body side of the sheet-like laminate on the surface of the fuel-side electrode molded body, or placing the sheet-like second intermediate layer molded body side of the sheet-like laminate on the oxygen-side electrode A method for producing a fuel cell, comprising: a step of forming a laminated molded article by laminating the molded article on a surface thereof; and a step of firing the laminated molded article. 焼成後、第２中間層又は第１中間層の表面に、酸素側電極材料又は燃料側電極材料を含有する成形体を作製し、熱処理して酸素側電極又は燃料側電極を作製する工程を具備することを特徴とする請求項２記載の燃料電池セルの製法。After sintering, a step of producing a molded body containing the oxygen-side electrode material or the fuel-side electrode material on the surface of the second intermediate layer or the first intermediate layer, and performing a heat treatment to produce the oxygen-side electrode or the fuel-side electrode The method for producing a fuel cell according to claim 2, wherein: 固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体と、シート状酸素側電極成形体とを順次積層してシート状成形体を作製する工程と、該シート状積層体のシート状第１中間層成形体側を燃料側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする燃料電池セルの製法。An oxygen-side electrode is provided on one side of the solid electrolyte, and a fuel-side electrode is provided on the other side, and first and second electrodes are provided between the solid electrolyte and the fuel-side electrode and between the solid electrolyte and the oxygen-side electrode. A method for producing a fuel cell comprising an intermediate layer formed therein, comprising: a sheet-shaped first intermediate layer molded article, a sheet-shaped solid electrolyte molded article, a sheet-shaped second intermediate layer molded article, and a sheet-shaped oxygen-side electrode. Forming a sheet-like molded body by sequentially laminating the molded body, and laminating the sheet-like first intermediate layer molded body side of the sheet-like laminated body on the surface of the fuel-side electrode molded body to produce a laminated molded body. And a step of firing the laminated molded body. 固体電解質の一方側に酸素側電極、他方側に燃料側電極を設けるとともに、前記固体電解質と前記燃料側電極との間、及び前記固体電解質と前記酸素側電極との間に第１、第２中間層をそれぞれ形成してなる燃料電池セルの製法であって、シート状燃料側電極成形体と、シート状第１中間層成形体と、シート状固体電解質成形体と、シート状第２中間層成形体とを順次積層してシート状成形体を作製する工程と、該シート状積層体のシート状第２中間層成形体側を酸素側電極成形体表面に積層して積層成形体を作製する工程と、該積層成形体を焼成する工程とを具備することを特徴とする燃料電池セルの製法。An oxygen-side electrode is provided on one side of the solid electrolyte, and a fuel-side electrode is provided on the other side, and first and second electrodes are provided between the solid electrolyte and the fuel-side electrode and between the solid electrolyte and the oxygen-side electrode. A method for producing a fuel cell, comprising forming an intermediate layer, wherein a sheet-shaped fuel-side electrode molded body, a sheet-shaped first intermediate layer molded body, a sheet-shaped solid electrolyte molded body, and a sheet-shaped second intermediate layer Forming a sheet-like molded body by sequentially laminating the molded body, and laminating the sheet-like second intermediate layer molded body side of the sheet-like laminated body on the surface of the oxygen-side electrode molded body to produce a laminated molded body. And a step of firing the laminated molded body. シート状積層体は、熱圧着若しくは冷間静水圧プレスにて作製されることを特徴とする請求項２乃至５のうちいずれかに記載の燃料電池セルの製法。The method for producing a fuel cell according to any one of claims 2 to 5, wherein the sheet-like laminate is produced by thermocompression bonding or cold isostatic pressing. 請求項１記載の燃料電池セルを複数収納容器内に収納してなることを特徴とする燃料電池。A fuel cell comprising a plurality of the fuel cells according to claim 1 stored in a storage container.
JP2002218949A 2002-07-26 2002-07-26 Fuel battery cell, its manufacturing method, and fuel battery Pending JP2004063226A (en)

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