JP3460793B2 - How the fuel cell works - Google Patents
How the fuel cell worksInfo
- Publication number
- JP3460793B2 JP3460793B2 JP15098898A JP15098898A JP3460793B2 JP 3460793 B2 JP3460793 B2 JP 3460793B2 JP 15098898 A JP15098898 A JP 15098898A JP 15098898 A JP15098898 A JP 15098898A JP 3460793 B2 JP3460793 B2 JP 3460793B2
- Authority
- JP
- Japan
- Prior art keywords
- fuel cell
- voltage
- battery
- fuel
- cell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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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
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- Fuel Cell (AREA)
- Inert Electrodes (AREA)
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、燃料電池の中でも
特に高分子電解質型燃料電池の作動方法に関する。
【０００２】
【従来の技術】通常、燃料電池の燃料は、都市ガスある
いはメタノールを改質した燃料ガスが用いられる。しか
しながら、特に高分子電解質型燃料電池（以下ＰＥＦＣ
と略す）の場合、燃料極には通常白金触媒が用いらるた
め、燃料ガス中に含まれる微量の一酸化炭素によって、
白金触媒が被毒され触媒活性が低下し、電池性能の大幅
な劣化が生じることが課題となっている。
【０００３】この現象を回避するため、いろいろな方法
が提案されている。その一つに、燃料ガス中のＣＯを、
電池導入前にＰｄ薄膜によって除去する水素分離法があ
る。この方法は、水素分離膜を挟んで一方の側に一定の
圧力を加え、選択的に水素のみを透過させる方法であ
る。この方法を用いると水素以外のガスは透過しないた
め、純水素のみが得られる。この方法は、半導体製造用
のプラントなどで実用化されおり、ＰＥＦＣ用としても
一部で開発が行われている。
【０００４】これ以外、燃料ガス中のＣＯ濃度の低減方
法としては、いわゆるＣＯ変成法が提案されている。こ
れはメタノールあるいは都市ガスを水蒸気改質し、そこ
で得た改質ガスを、ＣＯ変成触媒を用いてＣＯの除去を
行うものである（ＣＯ＋Ｈ２Ｏ→ＣＯ２＋Ｈ２）。通常
この方法では、ガス中のＣＯ濃度を０．４〜１．５％に
まで低減することができる。この程度までＣＯを低減で
きれば、同じＰｔ電極触媒を用いるリン酸型燃料電池用
の燃料としては使用可能である。しかしながら、ＰＥＦ
Ｃでもちいる燃料極の白金触媒の被毒を防止するために
は、ＣＯ濃度を少なくとも数十ｐｐｍレベルにまでする
必要があり、上記のＣＯ変成法だけではＰＥＦＣ用の燃
料ガスとして使用するには不十分である。
【０００５】そこで、ＣＯ変成後のガスに，あらためて
酸素（空気）を導入し、２００〜３００℃で酸化触媒を
用いて、さらにＣＯを酸化除去する提案がなされてい
る。ここで用いる酸化触媒としては、貴金属を担持した
アルミナ触媒等が提案されている。しかし、水素中の微
量ＣＯを、選択的かつ完全に酸化することは、非常に困
難である。
【０００６】この他、燃料ガスに直接空気を混入し、燃
料極でＣＯを酸化除去する方法も提案されている。この
方法は複雑な燃料ガス処理系が不必要であることから、
コンパクト性の点では優れているが、完全にＣＯを除去
することは困難である。
【０００７】この他、電極触媒を変えてＣＯ被毒に強い
合金触媒を用いることもいろいろ検討されているが、現
状ではその性能は不十分であり、全くＣＯを吸着しない
ような電極触媒を開発することは困難である。
【０００８】
【発明が解決しようとする課題】従来のＰｄ膜のような
金属水素化物膜を用いる方法は、高純度の水素が得られ
るためＰＥＦＣの燃料としては最適である。しかしなが
ら、非常に高価なＰｄ膜を用いるため、コスト面で課題
がある。また、基本的には圧力差により水素を得るため
装置の構造が複雑になるという課題もある。
【０００９】一方、ＣＯ変成とＣＯ酸化あるいは燃料ガ
スに空気を混入する方法を用いても、ＰＥＦＣの燃料と
して使用できる程度まで、十分にＣＯ濃度を低減するこ
とは困難である。特に、燃料電池起動時には大量のＣＯ
が燃料ガス中に含まれる危険性があり、十分時間をおい
て性能が安定してから燃料電池に導入するか、起動用の
水素ボンベを別に用意する必要がある。また、通常運転
時においても徐々にＣＯが燃料極に蓄積され電池性能が
低下する。一旦電池性能が低下してしまえば電池性能は
そのままでは復活せず、燃料電池の運転を一時中止し
て、大量の空気を導入してＣＯを酸化除去するか、電極
ごと交換する必要がある。
【００１０】このようなＣＯによる電池性能の低下を回
避あるいは復活させるための、容易で効果の高い燃料電
池の作動方法が望まれている。
【００１１】
【課題を解決するための手段】以上の課題を解決するた
め、本発明は、水素イオン伝導性の高分子電解質膜と、
前記高分子電解質膜の両面に配した触媒反応層を有する
電極層とを具備した固体高分子型燃料電池の作動方法で
あって、前記固体高分子型燃料電池の出力電圧を強制的
に低下させることで、前記電極層の触媒活性を高めるこ
とを特徴とする。
【００１２】このとき、電池の出力電圧を、単セル当た
り０Ｖ以上でかつ０．３Ｖ以下まで、１〜１０秒間、強
制的に低下させることが望ましい。
【００１３】また、電池の出力電圧を連続して断続的に
低下させることが有効である。
【００１４】
【発明の実施の形態】本発明の燃料電池の作動方法は、
水素イオン伝導性の高分子電解質膜と、前記高分子電解
質膜の両面に配した触媒反応層を有する電極層とを具備
した固体高分子型燃料電池で、炭化水素系の原料ガスを
改質して得られる燃料ガスと、酸化剤ガスとを導入し、
直流電力を発生する動作において、電池の出力電圧を適
時、強制的に低下させることにより、触媒反応部に吸着
した一酸化炭素を除去することで触媒活性を回復し、電
池の出力特性を維持するものである。
【００１５】本発明の作動法を用いると、これまで起動
時に必要であった起動用の水素処理を省略することがで
きる。また、一旦ＣＯ被毒により燃料電池の性能が低下
しても、触媒に吸着したＣＯを容易に除去でき、電池性
能を回復させることができる。
【００１６】以下、本発明の燃料電池の作動方法につい
て図面を参照して述べる。
【００１７】
【実施例】（実施例１）まず、以下の方法で高分子電解
質型燃料電池を構成した。アセチレンブラック系カ−ボ
ン粉末に、平均粒径約３０ の白金粒子を２５重量％担
持したものを反応電極の触媒とした。この触媒粉末をイ
ソプロパノ−ルに分散させた溶液に、パーフルオロカー
ボンスルホン酸の粉末をエチルアルコールに分散したデ
ィスパージョン溶液を混合し、ペースト状にした。この
ペーストを原料としスクリ−ン印刷法をもちいて、厚み
２５０μｍのカ−ボン不織布の一方の面に電極触媒層を
形成した。形成後の反応電極中に含まれる白金量は０．
５ｍｇ／ｃｍ2、パーフルオロカーボンスルホン酸の量
は１．２ｍｇ／ｃｍ2となるよう調整した。
【００１８】これらの極板は、正極・負極共に同一構成
とし、電極より一回り大きい面積に成形した。次に、プ
ロトン伝導性高分子電解質として、パーフルオロカーボ
ンスルホン酸を２５μｍの厚みに薄膜化したものを用
い、電解質膜の中心部の両面に、印刷した触媒層が電解
質膜側に接するようにホットプレスによって接合して、
電極／電解質接合体（ＭＥＡ）を作成した。
【００１９】次に、反応電極用とガスマニホ−ルド用の
孔を設け、板状に成型したガスケット状シールを作製し
た。この中心部にある反応電極用の孔に対して、前記Ｍ
ＥＡの反応電極部分が勘合するように、２枚のガスケッ
トシールでＭＥＡの電極周辺部の電解質膜部を挟みこん
だ。さらに非多孔質カ−ボン板を素材とするバイポ−ラ
板のガス流路が向かい合う形で、２枚のバイポ−ラ板の
間にＭＥＡとガスケットシールを挟んで、高分子電解質
型燃料電池を構成した。以上の板状成型体ガスケット状
シールは、厚さ２５０μｍのブチルゴムに、必要な孔を
打ち抜いて使用した。
【００２０】この高分子電解質型燃料電池の両外側に、
ガスマニホ−ルド用の孔を設けたヒ−タ−板・集電板・
絶縁板・エンドプレ−トを取り付け、最外側の両エンド
プレ−ト間を、ボルトとバネとナットを用いて、電極面
積に対して２０ｋｇ／ｃｍ2の圧力で締め付け、高分子
電解質型燃料電池の単電池を構成した。この単電池を５
０ヶ積層し、電池モジュールとした。
【００２１】このように作製した電池モジュールを、７
５℃に保持し、一方の電極側に７３℃の露点となるよう
加湿・加温した水素ガスを、もう一方の電極側に６８℃
の露点となるように加湿・加温した空気を供給した。そ
の結果、電流を外部に出力しない無負荷時には、０．９
８Ｖの電池開放電圧を得た。
【００２２】本発明の作動方法に用いた燃料電池のシス
テム構成を図１に示した。図１において、脱硫後の都市
ガスを、Ｓ／Ｃ（スチームカーボン比）＝３で改質器１
に導入し、水蒸気改質とＣＯ変成を行った。改質器１を
出た後の改質ガスは、Ｐｔ触媒が充填されたＣＯ酸化除
去装置２に、Ｏ2／ＣＯ比が１になるように導入され、
最終的に電池モジュール３に導入される。
【００２３】定常状態では、電池モジュールに導入され
る燃料ガス中のＣＯ濃度は１００ｐｐｍ以下になってい
た。但し、起動時には燃料ガス中のＣＯ濃度は１％以上
を示した。燃料電池の運転温度は８０℃、ガス加湿温度
は燃料ガスを７５℃、酸化剤ガス（空気）を６５℃に設
定した。
【００２４】まず、燃料電池起動直後に、何の処理も行
わずに燃料ガスを導入した場合の燃料電池の特性を評価
した。図２は、この時の電流−電圧特性を、純水素を導
入した場合と比較して示したものである。これより燃料
電池起動直後に未処理のままでは電池の特性が著しく低
下することが分かった。
【００２５】次に、本発明の作動方法の評価を行った。
すなわち、燃料電池の起動時に、電池出力の端子間に固
定抵抗を通じることで、電池の閉路電圧を２秒間、０．
２Ｖに低下させた後、電池性能を調べた。図３はこの時
の電流−電圧特性を先の未処理の場合と比較して示した
ものである。これより電圧を一時的に低下（短絡）させ
ることにより、電池性能が向上することが分かった。
【００２６】この原因は、燃料電池の出力電圧を強制的
に下げることで、上述のＭＥＡ中の電極電位がＣＯの酸
化電位にまで低下し、Ｐｔ触媒上に吸着したＣＯが酸化
されたためと考えられる。
【００２７】つぎに、燃料電池の出力電圧を強制的に下
げる時間を変えたときの電池性能を調べた。燃料電池の
起動時の出力電圧を、強制的に１０Ｖ、つまり単セルあ
たり０．２Ｖまで下げたときの１０Ｖを維持した時間
と、この工程を実施した後、燃料電池の出力電流を５０
０ｍＡ／ｃｍ2としたときの電池の閉路電圧を表１に示
した。表１において、電池電圧を強制的に低下する時間
が１０秒以下のときは、電池性能が良化するが、これよ
り長くすると、逆に電池性能が低下することが分かっ
た。
【００２８】
【表１】
【００２９】次に、電池出力電圧を強制的に低下させる
電圧を変えたときの、電池性能を調べた。表２は、電池
電圧を強制的に低下させた時間を５秒間に固定して、低
下させた電圧を変えたときの、この工程を経た後、電池
出力を２００ｍＡ／ｃｍ2としたときの、電池の閉路電
圧を示したものである。これより低下させた電圧が、単
セルあたり０〜０．３Ｖの範囲では、純水素を用いた場
合とほぼ同等の性能を示したが、それ以外では電池電圧
の復活率が小さく、純水素よりも５Ｖ以上悪くなった。
【００３０】
【表２】【００３１】以上の評価により、燃料電池の出力電圧を
強制的に下げる時間と電圧は、電池構成を考慮して有効
な範囲があることを見出した。電池電圧を強制的に低下
する時間を必要以上に長くすると、直列に接続した５０
ヶの単電池のうち、閉路電圧が０Ｖを切ってマイナスに
なる状態、つまり転極状態にいたるセルが発生してしま
うことによるものと考えられる。このような状況の発生
をさける手段としては、たとえば各単電池の電圧もモニ
ターしつつ、転極セルが発生しない範囲で全体の出力電
圧を強制的に下げる方法が有効である。
【００３２】（実施例２）本発明の第２の実施例は、実
施例１の燃料電池を用いて実施した。起動時に１時間以
上の時間をおいて、ＣＯ濃度が１００ｐｐｍ以下になっ
てから燃料電池に燃料ガスを導入した。その後５００ｍ
Ａ／ｃｍ2で１０００時間連続放電した時の電圧と時間
の関係を図４に示した。
【００３３】これより電圧が初期に比べ１０％も低下し
ていることが分かった。そこで、この時点で電池起電力
を一時的に低下させてみた。電池の出力電圧４７Ｖを５
Ｖまで５秒間低下させた後、再度５００ｍＡ／ｃｍ2で
放電を行った。この時の電池電圧は処理直前に比べ大幅
に向上することが分かった。
【００３４】次に、処理の回数を変えて同様に処理後の
特性を調べた。表３は各々の処理回数における処理後の
電池電圧を示したものである。これより一時的に電池起
電力を低下させる回数が多いほどその効果が高いことが
分かった。
【００３５】
【表３】
【００３６】これらの結果より、一時的に燃料電池の電
池出力電圧を強制的に低下させることにより、従来の課
題であった燃料電池起動時のＣＯによる被毒問題を解決
することができ、燃料ガスをそのまま用いることができ
ることを見出した。
【００３７】また、燃料電池通常運転時においてもＣＯ
により性能が低下した場合に、一時的に電池出力電圧を
強制的に低下させることにより、初期とほぼ同等の性能
まで回復することができることを見出した。
【００３８】さらに、一時的に電池起電力を低下させる
時間が１０秒以下、または回数が２回以上、または一時
的に低下させる電圧が単セル当たり０Ｖ〜０．３Ｖであ
る場合にその効果が大きいことが分かった。ここでは燃
料ガスに都市ガスを改質したものを用いたが、とくにこ
の燃料ガスの使用に限定されるものではない。また、燃
料電池に用いる電極触媒には本発明以外の合金触媒等を
用いることもできる。
【００３９】
【発明の効果】以上実施例から明らかなように、本発明
によれば、起動時にそのまま燃料ガスを導入することが
できる。また、一旦ＣＯにより燃料電池の性能が低下し
ても、電池起電力を一時的に低下させることにより、燃
料極に吸着したＣＯを容易に除去でき、電池性能を回復
させることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a polymer electrolyte fuel cell, particularly a fuel cell. 2. Description of the Related Art Normally, fuel for a fuel cell is city gas or fuel gas obtained by reforming methanol. However, in particular, polymer electrolyte fuel cells (hereinafter referred to as PEFCs)
Abbreviated as), a platinum catalyst is usually used for the fuel electrode, so a small amount of carbon monoxide contained in the fuel gas
The problem is that the platinum catalyst is poisoned, the catalytic activity is reduced, and the battery performance is significantly deteriorated. Various methods have been proposed to avoid this phenomenon. One of them is CO in fuel gas,
There is a hydrogen separation method in which a Pd thin film is removed before the battery is introduced. This method is a method in which a fixed pressure is applied to one side of a hydrogen separation membrane to selectively permeate only hydrogen. When this method is used, gases other than hydrogen do not permeate, so that only pure hydrogen is obtained. This method has been put to practical use in semiconductor manufacturing plants and the like, and has been partially developed for PEFC. [0004] In addition, as a method of reducing the CO concentration in the fuel gas, a so-called CO shift method has been proposed. In this method, methanol or city gas is steam reformed, and the reformed gas obtained therefrom is subjected to CO removal using a CO shift catalyst (CO + H2O → CO2 + H2). Usually, this method can reduce the CO concentration in the gas to 0.4 to 1.5%. If CO can be reduced to this extent, it can be used as a fuel for a phosphoric acid fuel cell using the same Pt electrode catalyst. However, PEF
In order to prevent the poisoning of the platinum catalyst of the fuel electrode using C, it is necessary to reduce the CO concentration to at least several tens of ppm, and the above-mentioned CO conversion method alone cannot be used as a fuel gas for PEFC. Is not enough. [0005] Therefore, it has been proposed that oxygen (air) is newly introduced into the gas after CO conversion, and CO is further oxidized and removed at 200 to 300 ° C using an oxidation catalyst. As the oxidation catalyst used here, an alumina catalyst supporting a noble metal or the like has been proposed. However, it is very difficult to selectively and completely oxidize trace CO in hydrogen. In addition, a method has been proposed in which air is directly mixed with fuel gas to oxidize and remove CO at the fuel electrode. Since this method does not require a complicated fuel gas treatment system,
Although excellent in compactness, it is difficult to completely remove CO. [0007] In addition, various studies have been made to use an alloy catalyst that is resistant to CO poisoning by changing the electrode catalyst, but at present the performance is insufficient, and an electrode catalyst that does not adsorb CO at all has been developed. It is difficult to do. [0008] The conventional method using a metal hydride film such as a Pd film is most suitable as a fuel for PEFC because high-purity hydrogen can be obtained. However, since an extremely expensive Pd film is used, there is a problem in cost. In addition, there is also a problem that the structure of the apparatus is basically complicated to obtain hydrogen by a pressure difference. On the other hand, even if a method of CO conversion and CO oxidation or a method of mixing air into a fuel gas is used, it is difficult to sufficiently reduce the CO concentration to such an extent that it can be used as a fuel for PEFC. In particular, a large amount of CO
There is a danger of being included in the fuel gas, and it is necessary to introduce the fuel into the fuel cell after the performance has been stabilized after a sufficient time, or to prepare a separate hydrogen cylinder for startup. Further, even during normal operation, CO is gradually accumulated in the fuel electrode, and the cell performance is reduced. Once the battery performance is reduced, the battery performance does not recover as it is, and it is necessary to suspend the operation of the fuel cell and introduce a large amount of air to oxidize and remove CO or replace the entire electrode. There is a demand for an easy and effective fuel cell operation method for avoiding or restoring the deterioration of cell performance due to such CO. [0011] In order to solve the above problems, the present invention provides a hydrogen ion conductive polymer electrolyte membrane,
An operation method of a polymer electrolyte fuel cell, comprising: an electrode layer having a catalyst reaction layer disposed on both sides of the polymer electrolyte membrane, wherein the output voltage of the polymer electrolyte fuel cell is forcibly reduced. Thereby, the catalytic activity of the electrode layer is enhanced. At this time, it is desirable to forcibly reduce the output voltage of the battery from 0 V or more to 0.3 V or less per unit cell for 1 to 10 seconds . Further, it is effective to continuously and intermittently lower the output voltage of the battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for operating a fuel cell according to the present invention is as follows.
In a polymer electrolyte fuel cell comprising a hydrogen ion conductive polymer electrolyte membrane and an electrode layer having a catalytic reaction layer disposed on both sides of the polymer electrolyte membrane, a hydrocarbon-based source gas is reformed. Fuel gas and oxidant gas obtained by
In the operation of generating DC power, the output voltage of the battery is forcibly reduced in a timely manner, thereby removing the carbon monoxide adsorbed on the catalytic reaction unit, thereby recovering the catalytic activity and maintaining the output characteristics of the battery. Things. By using the operation method of the present invention, it is possible to omit the hydrogen treatment for starting which has been required at the time of starting. Further, even if the performance of the fuel cell is once deteriorated due to CO poisoning, the CO adsorbed on the catalyst can be easily removed, and the cell performance can be restored. Hereinafter, a method of operating the fuel cell according to the present invention will be described with reference to the drawings. EXAMPLE 1 First, a polymer electrolyte fuel cell was constructed by the following method. An acetylene black-based carbon powder carrying 25% by weight of platinum particles having an average particle size of about 30 was used as a catalyst for the reaction electrode. A dispersion solution in which a powder of perfluorocarbon sulfonic acid was dispersed in ethyl alcohol was mixed with a solution in which this catalyst powder was dispersed in isopropanol to form a paste. Using this paste as a raw material, an electrode catalyst layer was formed on one surface of a carbon nonwoven fabric having a thickness of 250 μm using a screen printing method. After the formation, the amount of platinum contained in the reaction electrode is 0.1.
5 mg / cm 2, the amount of perfluorocarbon sulfonic acid was adjusted to be 1.2 mg / cm 2. These electrode plates had the same configuration for both the positive electrode and the negative electrode, and were formed to have an area slightly larger than the electrodes. Next, as the proton conductive polymer electrolyte, perfluorocarbon sulfonic acid thinned to a thickness of 25 μm was used, and hot pressing was performed on both surfaces of the center of the electrolyte membrane so that the printed catalyst layers were in contact with the electrolyte membrane. Joined by
An electrode / electrolyte assembly (MEA) was made. Next, holes for the reaction electrode and the gas manifold were provided, and a gasket-like seal molded in a plate shape was produced. The hole for the reaction electrode at the center is filled with the M
The electrolyte membrane at the periphery of the MEA electrode was sandwiched between two gasket seals so that the reaction electrode portion of the EA fit. Further, a polymer electrolyte fuel cell was constructed by sandwiching an MEA and a gasket seal between two bipolar plates in such a manner that gas flow paths of a bipolar plate made of a nonporous carbon plate faced each other. . The above-mentioned gasket-like seal in the form of a plate was used by punching out necessary holes in butyl rubber having a thickness of 250 μm. On both outer sides of the polymer electrolyte fuel cell,
Heater plate, current collector plate, and gas manifold
An insulating plate and an end plate are attached, and the outermost end plates are tightened between the outermost end plates with a bolt, a spring, and a nut at a pressure of 20 kg / cm 2 with respect to the electrode area. A battery was configured. This cell is 5
Zero batteries were stacked to form a battery module. The battery module manufactured as described above is
A hydrogen gas kept at 5 ° C. and humidified and heated to a dew point of 73 ° C. on one electrode side and 68 ° C. on the other electrode side
Humidified and heated air was supplied so as to have a dew point. As a result, when there is no load in which no current is output to the outside, 0.9
An open-circuit voltage of 8 V was obtained. FIG. 1 shows a system configuration of the fuel cell used in the operation method of the present invention. In FIG. 1, a city gas after desulfurization is supplied to a reformer 1 at S / C (steam carbon ratio) = 3.
And subjected to steam reforming and CO conversion. The reformed gas after leaving the reformer 1 is introduced into the CO oxidation removing device 2 filled with a Pt catalyst so that the O 2 / CO ratio becomes 1;
Finally, it is introduced into the battery module 3. In a steady state, the CO concentration in the fuel gas introduced into the battery module was less than 100 ppm. However, at the time of startup, the CO concentration in the fuel gas was 1% or more. The operating temperature of the fuel cell was set at 80 ° C., the gas humidification temperature was set at 75 ° C. for the fuel gas, and 65 ° C. for the oxidizing gas (air). First, the characteristics of the fuel cell when fuel gas was introduced immediately after the fuel cell was started without any processing were evaluated. FIG. 2 shows the current-voltage characteristics at this time in comparison with the case where pure hydrogen is introduced. From this, it was found that the characteristics of the cell were significantly reduced if the fuel cell was left untreated immediately after the start of the fuel cell. Next, the operation method of the present invention was evaluated.
That is, when the fuel cell is started, a fixed resistance is passed between the terminals of the battery output so that the closed circuit voltage of the battery is reduced to 0.
After reducing the voltage to 2 V, the battery performance was examined. FIG. 3 shows the current-voltage characteristics at this time in comparison with the untreated case. From this, it was found that the battery performance was improved by temporarily lowering (short-circuiting) the voltage. The cause is considered to be that the electrode potential in the MEA was lowered to the oxidation potential of CO by forcibly reducing the output voltage of the fuel cell, and CO adsorbed on the Pt catalyst was oxidized. Can be Next, the cell performance when the output voltage of the fuel cell was forcibly reduced was changed. The time during which the output voltage at the start of the fuel cell was forcibly maintained at 10 V, that is, 10 V when the voltage was reduced to 0.2 V per unit cell, and the output current of the fuel cell was reduced by 50% after performing this step.
Table 1 shows the closing voltage of the battery at 0 mA / cm 2 . In Table 1, it was found that when the time for forcibly lowering the battery voltage was 10 seconds or less, the battery performance was improved. However, when the time was longer than this, the battery performance was deteriorated. [Table 1] Next, the battery performance when the voltage for forcibly decreasing the battery output voltage was changed was examined. Table 2 shows that the time when the battery voltage was forcibly reduced was fixed to 5 seconds and the reduced voltage was changed. When the battery output was set to 200 mA / cm 2 after this step, It shows the closed circuit voltage of the battery. When the reduced voltage was in the range of 0 to 0.3 V per unit cell, the performance was almost the same as that when pure hydrogen was used. Also got worse by more than 5V. [Table 2] From the above evaluation, it has been found that the time and voltage for forcibly reducing the output voltage of the fuel cell have an effective range in consideration of the cell configuration. If the time for forcibly lowering the battery voltage is made longer than necessary, 50
This is considered to be due to the occurrence of a cell in which the closed circuit voltage becomes less than 0 V and becomes negative, that is, a cell that is in a reversal state, among the four single cells. As a means for preventing such a situation from occurring, for example, a method is effective in which the voltage of each cell is monitored and the entire output voltage is forcibly reduced within a range in which no reversal cell occurs. (Embodiment 2) The second embodiment of the present invention was carried out using the fuel cell of Embodiment 1. After one hour or more at the start-up, the fuel gas was introduced into the fuel cell after the CO concentration became 100 ppm or less. Then 500m
FIG. 4 shows the relationship between voltage and time when the battery was continuously discharged at A / cm 2 for 1000 hours. From this, it was found that the voltage was reduced by 10% from the initial level. Therefore, at this point, the battery electromotive force was temporarily reduced. Battery output voltage 47V to 5
After the voltage was lowered to V for 5 seconds, discharge was performed again at 500 mA / cm 2 . It was found that the battery voltage at this time was significantly improved as compared to immediately before the treatment. Next, the characteristics after the processing were similarly examined by changing the number of times of the processing. Table 3 shows the battery voltage after the processing at each processing frequency. From this, it was found that the effect was higher as the number of times the battery electromotive force was temporarily reduced was increased. [Table 3] From these results, it is possible to solve the conventional problem of poisoning by CO at the start of the fuel cell by forcibly lowering the cell output voltage of the fuel cell temporarily, It has been found that the gas can be used as it is. Also, during normal operation of the fuel cell, CO 2
It has been found that, when the performance is reduced due to, the battery output voltage can be temporarily forcibly reduced to recover the performance to almost the same level as the initial stage. Further, when the time for temporarily lowering the battery electromotive force is 10 seconds or less, or the number of times is twice or more, or the voltage for temporarily lowering the voltage is 0 V to 0.3 V per cell, the effect is reduced. It turned out to be big. Here, fuel gas obtained by reforming city gas is used, but the use of this fuel gas is not particularly limited. Further, an alloy catalyst other than the present invention can be used as the electrode catalyst used in the fuel cell. As is apparent from the above embodiments, according to the present invention, the fuel gas can be directly introduced at the time of starting. Further, even if the performance of the fuel cell is once lowered by CO, by temporarily lowering the cell electromotive force, the CO adsorbed on the fuel electrode can be easily removed, and the cell performance can be recovered.
【図面の簡単な説明】
【図１】本発明の第１の実施例に用いた燃料電池システ
ムの構成図
【図２】本発明の第１の実施例に用いた燃料電池の電流
−電圧特性を示した図
【図３】本発明の第１の実施例に用いた燃料電池の電流
−電圧特性を示した図
【図４】本発明の第２の実施例に用いた燃料電池の運転
時間と電圧の関係を示した図
【符号の説明】
１ 改質器
２ ＣＯ酸化除去装置
３ 燃料電池BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a fuel cell system used in a first embodiment of the present invention. FIG. 2 is a current-voltage characteristic of a fuel cell used in a first embodiment of the present invention. FIG. 3 is a diagram showing current-voltage characteristics of the fuel cell used in the first embodiment of the present invention. FIG. 4 is an operation time of the fuel cell used in the second embodiment of the present invention. Diagram showing the relationship between voltage and voltage [Description of References] 1 Reformer 2 CO oxidation removal device 3 Fuel cell
───────────────────────────────────────────────────── フロントページの続き (72)発明者 西田 和史 大阪府門真市大字門真1006番地 松下電 器産業株式会社内 (56)参考文献 特開 平６−68879（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01M 8/04 H01M 8/10 H01M 4/86 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazufumi Nishida 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-6-68879 (JP, A) (58) Survey Field (Int.Cl. 7 , DB name) H01M 8/04 H01M 8/10 H01M 4/86
Claims (1)
前記高分子電解質膜の両面に配した白金触媒を含む触媒
層を有する電極層とを具備した固体高分子型燃料電池の
動作方法であって、前記固体高分子型燃料電池の出力電
圧を、単セルあたり０Ｖ以上でかつ０．３Ｖ以下に１〜
１０秒間、強制的に低下させることで、前記触媒層の触
媒活性を高めることを特徴とする固体高分子型燃料電池
の動作方法。(57) [Claims] [Claim 1] A hydrogen ion conductive polymer electrolyte membrane,
An electrode layer having a catalyst layer containing a platinum catalyst disposed on both sides of the polymer electrolyte membrane, wherein the output voltage of the polymer electrolyte fuel cell is at 0V or more per cell and 1 below 0.3V
A method for operating a polymer electrolyte fuel cell, wherein the catalytic activity of the catalyst layer is increased by forcibly lowering it for 10 seconds .
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15098898A JP3460793B2 (en) | 1998-06-01 | 1998-06-01 | How the fuel cell works |
| US09/322,948 US6187464B1 (en) | 1998-06-01 | 1999-05-28 | Method for activating fuel cell |
| EP08011420A EP1981112A3 (en) | 1998-06-01 | 1999-06-01 | Method for activating a fuel cell |
| CN99107155A CN1113420C (en) | 1998-06-01 | 1999-06-01 | Activation method for fuel battery |
| CNB2006100054331A CN100369311C (en) | 1998-06-01 | 1999-06-01 | Method for operating fuel cell |
| CNB021473897A CN1238922C (en) | 1998-06-01 | 1999-06-01 | Fuel cell activating method |
| EP99109371A EP0961334A3 (en) | 1998-06-01 | 1999-06-01 | Method for activating fuel cell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15098898A JP3460793B2 (en) | 1998-06-01 | 1998-06-01 | How the fuel cell works |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11345624A JPH11345624A (en) | 1999-12-14 |
| JP3460793B2 true JP3460793B2 (en) | 2003-10-27 |
Family
ID=15508840
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15098898A Expired - Lifetime JP3460793B2 (en) | 1998-06-01 | 1998-06-01 | How the fuel cell works |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3460793B2 (en) |
| CN (1) | CN100369311C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007123077A (en) * | 2005-10-28 | 2007-05-17 | Toyota Motor Corp | Fuel cell system |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3475869B2 (en) | 1999-09-17 | 2003-12-10 | 松下電器産業株式会社 | Polymer electrolyte fuel cell and method for recovering its characteristics |
| WO2001059864A1 (en) | 2000-02-08 | 2001-08-16 | Matsushita Electric Industrial Co., Ltd. | Polymer electrolyte fuel cell |
| AU2003219726A1 (en) | 2002-02-06 | 2003-09-02 | Battelle Memorial Institute | Methods of removing contaminants from a fuel cell electrode |
| JP4547853B2 (en) * | 2002-10-07 | 2010-09-22 | パナソニック株式会社 | Operation method and characteristic recovery method of polymer electrolyte fuel cell |
| JP2006080005A (en) * | 2004-09-10 | 2006-03-23 | Fuji Electric Holdings Co Ltd | Gas supply method of fuel cell and fuel cell power generation system |
| JP4852241B2 (en) * | 2004-12-27 | 2012-01-11 | 東芝燃料電池システム株式会社 | Operation method of fuel cell power generation system |
| JP2007149574A (en) | 2005-11-30 | 2007-06-14 | Toyota Motor Corp | Fuel cell system |
| JP4905847B2 (en) * | 2005-11-30 | 2012-03-28 | トヨタ自動車株式会社 | Fuel cell system |
| JP4761162B2 (en) * | 2007-03-07 | 2011-08-31 | トヨタ自動車株式会社 | Fuel cell system |
| JP2009272217A (en) * | 2008-05-09 | 2009-11-19 | Three M Innovative Properties Co | Activation method for membrane electrode assembly, and membrane electrode assembly as well as solid polymer fuel cell using same |
| FR2936104A1 (en) * | 2008-09-12 | 2010-03-19 | Rech S De L Ecole Nationale Su | Process to conduct the operation of a fuel cell, comprises introducing a determined quantity of catalyst in a hydrogen stream or oxygen stream for the hydrolysis of sulfonic anhydrides formed during the functioning of the cell |
| CN102097631B (en) * | 2009-12-09 | 2013-03-27 | 华为技术有限公司 | Method and device for activating proton exchange membrane fuel cell |
| CN105762382A (en) * | 2014-12-16 | 2016-07-13 | 中国科学院大连化学物理研究所 | Starting method for direct liquid fuel cell system after long-term storage |
| US10439241B2 (en) * | 2015-10-28 | 2019-10-08 | GM Global Technology Operations LLC | Methods and processes to recover the voltage loss due to anode contamination |
| CN110571446B (en) * | 2019-09-02 | 2021-03-16 | 武汉中极氢能产业创新中心有限公司 | Method for activating fuel cell and preventing/improving dry film |
| CN110649291B (en) * | 2019-09-27 | 2022-08-02 | 先进储能材料国家工程研究中心有限责任公司 | Rapid activation method for proton exchange membrane fuel cell |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4910099A (en) * | 1988-12-05 | 1990-03-20 | The United States Of America As Represented By The United States Department Of Energy | Preventing CO poisoning in fuel cells |
| JP3358222B2 (en) * | 1992-12-25 | 2002-12-16 | 松下電器産業株式会社 | Activation method of polymer electrolyte fuel cell |
| JP3584511B2 (en) * | 1994-12-12 | 2004-11-04 | トヨタ自動車株式会社 | Operation control method of polymer electrolyte fuel cell |
-
1998
- 1998-06-01 JP JP15098898A patent/JP3460793B2/en not_active Expired - Lifetime
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007123077A (en) * | 2005-10-28 | 2007-05-17 | Toyota Motor Corp | Fuel cell system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100369311C (en) | 2008-02-13 |
| JPH11345624A (en) | 1999-12-14 |
| CN1801516A (en) | 2006-07-12 |
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