JP3810178B2

JP3810178B2 - Method for producing polymer electrolyte fuel cell

Info

Publication number: JP3810178B2
Application number: JP11568197A
Authority: JP
Inventors: 一仁羽藤; 栄一安本; 久朗行天; 孝治蒲生
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1997-05-06
Filing date: 1997-05-06
Publication date: 2006-08-16
Anticipated expiration: 2017-05-06
Also published as: JPH10308228A

Description

【０００１】
本発明は、高分子電解質型燃料電池の製造方法に関する。
【０００２】
【従来の技術】
従来の高分子電解質型燃料電池は、電解質である炭化フッソ系の高分子電解質薄膜と、アノ−ドおよびカソ−ドの電極、さらにカ−ボンあるいは金属製のセパレ−タ−や冷却板から構成されてきた。
【０００３】
電池反応に寄与する電極と電解質は、貴金属触媒を担持したカ−ボン粉末と電解質と同等の材料の混合物を構成材料とし、これに場合によってはフルオロカ−ボン化合物系の撥水材などを添加した混合物を、カ−ボン繊維から構成されるカ−ボンペ−パ−などに保持し、電解質である高分子膜と接合して構成してきた。通常、アノ−ドおよびカソ−ドの構成材料は同一であり、炭化水素系燃料を改質した水素リッチなガスを燃料とする場合、改質ガス中に含まれる一酸化炭素による触媒の被毒を抑制するため、アノ−ド側のみにルテニウムなどの耐ＣＯ被毒材料を添加して構成することも考えられてきた。
【０００４】
電解質は、スルホン基を含む炭化フッソ系の高分子であり、プロトン伝導性の電解質である。燃料電池の性能を向上させるためには、電解質のイオン伝導度を向上させることが重要な因子の一つであるため、通常は高分子電解質の膜厚を薄くすることによって内部抵抗を小さくすることが試みられている。
【０００５】
【発明が解決しょうとする課題】
しかしながら、従来の高分子電解質型燃料電池では、高分子電解質を薄くすればするほど電解質の抵抗は小さくなるが、それに反して電解質膜の機械的強度が小さくなると言う課題が有った。
【０００６】
本発明は、従来の高分子電解質型燃料電池のこの様な課題を考慮し、高分子電解質のイオン伝導度を実質上維持したまま、高分子電解質の機械的強度を従来に比べてより一層強くすることが出来る高分子電解質型燃料電池の製造方法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
本発明は、高分子電解質と、その高分子電解質を挟持するガス拡散電極としてのアノ−ドとカソ−ドとを有し、前記アノ−ドおよびカソ−ドが、電極触媒を担持したカ−ボン粉末を主体とする電極触媒層と、前記電極触媒を担持していないカ−ボン粉末又はカ−ボン繊維を主体とするガス拡散相とから構成されている高分子電解質型燃料電池の製造方法であって、前記高分子電解質の少なくとも一方の面の外周部付近に炭化フッソ系の樹脂を被覆する樹脂被覆工程と、前記樹脂被覆工程の後、前記少なくとも一方の面における前記炭化フッソ系樹脂で被覆されていない前記高分子電解質の実質上中心部に、前記炭化フッソ系樹脂の内周端部と接する大きさの電極触媒層を形成する電極触媒層形成工程と、前記電極触媒層形成工程の後、前記電極触媒層より大きいガス拡散相を前記電極触媒層と接するよう接合する接合工程とを備えている高分子電解質型燃料電池の製造方法である。
【００１１】
このような構成により、例えば、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度を強くすることが可能である。
【００１２】
【発明の実施の形態】
以下、本発明にかかる高分子電解質型燃料電池の製造方法、ならびに、本発明に関連する技術の高分子電解質型燃料電池及びその製造方法の実施の形態を図面を参照しながら説明する。
【００１３】
図１は、本発明に関連する技術の高分子電解質型燃料電池の概略の構成を説明するためのイメ−ジ図であり、同図を用いて本実施の形態の構成及び作用を述べる。
【００１４】
図１中において、１が高分子電解質膜、２が炭化フッソ系樹脂の相である。高分子電解質は、通常１０μｍ〜１００μｍ程度の膜厚を有するプロトン伝導体であり、発明が解決しょうとする課題の欄で述べた様に、抵抗を小さくするため膜厚を薄くすると機械的強度が弱くなり、電極１３のアノ−ド側とカソ−ド側に導入するガスの差圧などが生じると電解質膜が破れて、アノ−ドガスとカソ−ドガスのクロスリ−クが発生しやすくなる。ここで、電極１３は、図１に示した高分子電解質膜１上で、炭化フッソ系樹脂の相２に囲まれた中央部の四角形の穴の位置に設けられている。尚、図１は、高分子電解質膜１上において、アノードとカソードの双方の電極の内、その片側の電極の記載を省略している。
【００１５】
このとき、アノ−ドとカソ−ドに挟持された部分の電解質膜の機械的強度は比較的強く、電極と接合されていない部分の電解質膜が破れることがほとんどである。
【００１６】
そこで、本実施の形態の様に、高分子電解質と電極との接合面以外の電極周辺部の高分子電解質の少なくとも一方の面を炭化フッ素系樹脂で被覆することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度を強くすることが可能である。
【００１７】
尚、高分子電解質１は、一般的にスルホン基を含む炭化フッソ系の高分子が利用される。そのため補強用に用いる炭化フッソ系樹脂の相２もこれと同じスルホン基を含む炭化フッソ系樹脂を用いても良いが、スルホン基を含む炭化フッソ系樹脂は高価であるので、テフロン等を用いる方が、価格的に安くなり更に良い。
【００１８】
次に、図２は、本発明に関連する他の技術の高分子電解質型燃料電池の概略の構成を説明するためのイメ−ジ図であり、同図を用いて本実施の形態の構成及び作用を述べる。
【００１９】
図２において、１が高分子電解質膜、２が炭化フッソ系樹脂の相、３が電極である。高分子電解質は、通常１０μｍ〜１００μｍ程度の膜厚を有するプロトン伝導体であり、抵抗を小さくするため膜厚を薄くすると機械的強度が弱くなり、アノ−ド側とカソ−ド側に導入するガスの差圧などが生じると電解質膜が破れて、アノ−ドガスとカソ−ドガスのクロスリ−クが発生しやすくなる。このとき、アノ−ドとカソ−ドに挟持された部分の電解質膜の機械的強度は比較的強く、電極と接合されていない部分の電解質膜が破れることがほとんどである。特に、電極周辺のエッジ部で電解質膜が破れる場合が多い。そこで、高分子電解質１と電極３との接合面以外の電極周辺部の高分子電解質の少なくとも一方の面を炭化フッ素系樹脂２で被覆し、炭化フッソ系樹脂で被覆されていない高分子電解質の中心部の面積より大きい電極３を有して構成することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度を強くすることが可能である。
【００２０】
次に、図３は、本発明の高分子電解質型燃料電池の製造方法の一実施の形態により得られる高分子電解質型燃料電池の概略の構成を説明するためのイメ−ジ図であり、同図を用いて本実施の形態の構成及び作用を述べる。
【００２１】
図３において、１が高分子電解質膜、２が炭化フッソ系樹脂の相、３３が電極の一部を構成するガス拡散相、４が電極の一部を構成する電極触媒層である。高分子電解質は、通常１０μｍ〜１００μｍ程度の膜厚を有するプロトン伝導体であり、抵抗を小さくするため膜厚を薄くすると機械的強度が弱くなり、アノ−ド側とカソ−ド側に導入するガスの差圧などが生じると電解質膜が破れて、アノ−ドガスとカソ−ドガスのクロスリ−クが発生しやすくなる。このとき、アノ−ドとカソ−ドに挟持された部分の電解質膜の機械的強度は比較的強く、電極と接合されていない部分の電解質膜が破れることがほとんどである。特に、電極周辺のエッジ部で電解質膜が破れる場合が多い。そこで、高分子電解質１の少なくとも一方の面の周縁部（外周部付近）に炭化フッソ系の樹脂２を被覆し、炭化フッソ系樹脂で被覆した高分子電解質の中心部に炭化フッソ系樹脂と接する大きさの電極触媒層４を被覆し、電極触媒層より大きいガス拡散相３３を電極触媒層４と接するよう接合することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度を強くすることが可能である。
【００２２】
次に、図４は、本発明の高分子電解質型燃料電池の製造方法の他の実施の形態により得られる高分子電解質型燃料電池の概略の構成を説明するためのイメ−ジ図であり、同図を用いて本実施の形態の構成及び作用を述べる。
【００２３】
図４において、１が高分子電解質膜、２が炭化フッソ系樹脂の相、３３が電極の一部を構成するガス拡散相、４が電極の一部を構成する電極触媒層である。高分子電解質は、通常１０μｍ〜１００μｍ程度の膜厚を有するプロトン伝導体であり、抵抗を小さくするため膜厚を薄くすると機械的強度が弱くなり、アノ−ド側とカソ−ド側に導入するガスの差圧などが生じると電解質膜が破れて、アノ−ドガスとカソ−ドガスのクロスリ−クが発生しやすくなる。このとき、アノ−ドとカソ−ドに挟持された部分の電解質膜の機械的強度は比較的強く、電極と接合されていない部分の電解質膜が破れることがほとんどである。特に、電極周辺のエッジ部で電解質膜が破れる場合が多い。そこで、高分子電解質１の両方の面の周縁部に炭化フッソ系の樹脂２を被覆し、炭化フッソ系樹脂で被覆した高分子電解質の中心部に炭化フッソ系樹脂と接する大きさの電極触媒層４を被覆し、電極触媒層より大きいガス拡散相３３を電極触媒層と接するよう接合することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度を強くすることが可能である。
【００２４】
次に、図５は、本発明の高分子電解質型燃料電池の製造方法の他の実施の形態により得られる高分子電解質型燃料電池の概略の構成を説明するためのイメ−ジ図であり、同図を用いて本実施の形態の構成及び作用を述べる。
【００２５】
図５において、１が高分子電解質膜、２が炭化フッソ系樹脂の相、３３が電極の一部を構成するガス拡散相、４が電極の一部を構成する電極触媒層、５が燃料である水素や酸化材である空気などを電極に供給するためのガスマニホ−ルドである。高分子電解質は、通常１０μｍ〜１００μｍ程度の膜厚を有するプロトン伝導体であり、抵抗を小さくするため膜厚を薄くすると機械的強度が弱くなり、アノ−ド側とカソ−ド側に導入するガスの差圧などが生じると電解質膜が破れて、アノ−ドガスとカソ−ドガスのクロスリ−クが発生しやすくなる。このとき、アノ−ドとカソ−ドに挟持された部分の電解質膜の機械的強度は比較的強く、電極と接合されていない部分の電解質膜が破れることがほとんどである。特に、電極周辺のエッジ部で電解質膜が破れる場合が多い。そこで、高分子電解質１の両方の面の周縁部に炭化フッソ系の樹脂２を被覆し、炭化フッソ系樹脂２で被覆した高分子電解質の中心部に炭化フッソ系樹脂と接する大きさの電極触媒層４を被覆し、電極触媒層より大きいガス拡散相３３を電極触媒層と接するよう接合することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度を強くすることが可能である。また、このとき炭化フッ素系の樹脂の相２はガスマニホ−ルドの周縁部をガスシ−ルするガスケットの役目を同時に果たしている。
【００２６】
次に、具体的な実験例（上述した本発明に関連する技術の高分子電解質型燃料電池の単セルを製造する場合の例を含む）を図面を用いて述べ、同時に本発明の高分子電解質型燃料電池の製造方法の実施の形態についても説明する。
（実験例１）
本実験例は、図１で述べた構成とほぼ対応した本発明に関連する技術の一例である高分子電解質型燃料電池の単セルを製造する場合の例である。
【００２７】
即ち、本実験例では、高分子電解質として１６ｃｍ角に切断したデュポン社製のナフィオン１１２（図１の高分子電解質膜１に対応）を用いた。アセチレンブラック系カ−ボン粉末に平均粒径約３０オングストロームの白金触媒を３０ｗｔ％担持した触媒担持カ−ボン粉末と、デュポン社製のナフィオン溶液を酢酸ブチル溶媒に分散し、ペ−スト状の電極触媒スラリ−を得た。この電極触媒スラリ−を、１０ｃｍ角に切断した東レ製のカ−ボン不織布の一方の面に、白金触媒量がカ−ボン不織布の面積に対して０．３ｍｇ／ｃｍ²となるようスクリ−ン印刷法により塗布し、電極（図１の電極１３に対応）とした。カ−ボン不織布に塗布した電極触媒スラリ−を粗乾燥後、塗布面が高分子電解質膜と接するようにそれら２枚の電極で高分子電解質膜の中央部を挟持し、１５０℃、５０ｋｇ／ｃｍ²でホットプレスして高分子電解質膜と電極を接合した。接合した電極／高分子電解質膜接合体の電極周辺部の高分子電解質膜の一方の面に、炭化フッ素系樹脂製の粘着剤付きテ−プを（幅：１ｃｍ、厚さ：５０μｍ）、電極との隙間ができないように張り付け高分子電解質膜を補強した。即ち、この場合、粘着剤付きテ−プを４枚用意して、それらを電極の周辺に張り付けるものである（図１の炭化フッソ系樹脂の相２に対応）。
【００２８】
この電極／高分子電解質膜接合体を、グラッシ−カ−ボン製のセパレ−タ−に組み込んで高分子電解質型燃料電池の単セルを構成した.高分子電解質型燃料電池は５０℃の電池温度で作動させ、アノ−ド側には６０℃で加湿した純水素を、カソ−ド側には４０℃で加湿した空気をそれぞれ大気圧で供給し、アノ−ド側の燃料利用率は、電流密度１０００ｍＡ／ｃｍ²のとき９５％となるよう水素流量を調整した。
【００２９】
本実験例に基づく高分子電解質型燃料電池の性能曲線６（図６では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池の性能曲線７（図６では、黒丸で表した）を図６に示す。図６より、本実験例により得られる高分子電解質型燃料電池は従来と同等の性能が得られることが確認された。図６の横軸、縦軸は、それぞれ電流密度と電池電圧を示している。
【００３０】
次に、本実験例に基づく高分子電解質型燃料電池のクロスリ−ク特性曲線８（図７では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池のクロスリ−ク特性曲線９（図７では、黒丸で表した）を図７に示す。このとき、高分子電解質型燃料電池は５０℃の電池温度で作動させ、カソ−ド側には５０℃で加湿した空気を大気圧で供給した。アノ−ド側は、出口を絞り、無加湿の純水素を所定の圧力で供給し、アノ−ド側とカソ−ド側に所定の差圧が発生するよう調整して、アノ−ド側にクロスリ−クした空気中の窒素量をガスクロマトグラフィ−で定量して、クロスリ−ク量を求めた。図７より、明らかに本実験例により得られた本発明に関連する技術の一例である高分子電解質型燃料電池は、その性能が維持されたまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度が強くなり、耐差圧特性も向上することが確認された。試験後、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池を解体し調べたところ、電極周辺部、つまり電極と高分子電解質膜との界面近傍の高分子電解質膜が破れていることが判明した。
（実験例２）
本実験例は、図２で述べた構成とほぼ対応した本発明に関連する技術の一例である高分子電解質型燃料電池の単セルを製造する場合の例である。
【００３１】
即ち、高分子電解質として１６ｃｍ角に切断したデュポン社製のナフィオン１１２（図２の高分子電解質膜１に対応）を用いた。中心部１０ｃｍ角を切断して穴をあけた、１５ｃｍ角の炭化フッソ系樹脂製の粘着剤付きシ−ト（厚さ：５０μｍ、図１の炭化フッソ系樹脂の相２に対応）を、上記高分子電解質膜の一方の面に張り付けた。アセチレンブラック系カ−ボン粉末に平均粒径約３０オングストロームの白金触媒を３０ｗｔ％担持した触媒担持カ−ボン粉末と、デュポン社製のナフィオン溶液を酢酸ブチル溶媒に分散し、ペ−スト状の電極触媒スラリ−を得た。この電極触媒スラリ−を、１０．２ｃｍ角に切断した東レ製のカ−ボン不織布の一方の面に、白金触媒量がカ−ボン不織布の面積に対して０．３ｍｇ／ｃｍ²となるようスクリ−ン印刷法により塗布し、電極（図２の電極３に対応）とした。カ−ボン不織布に塗布した電極触媒スラリ−を粗乾燥後、塗布面が高分子電解質膜と接するように２枚の電極で炭化フッ素系樹脂シ−ト付きの高分子電解質膜を挟持し、１５０℃、５０ｋｇ／ｃｍ²でホットプレスして高分子電解質膜と電極を接合した。このとき炭化フッ素系樹脂シ−トの中心部の１０ｃｍ角の穴の部分に電極がきて、高分子電解質膜と電極が直接接合し、かつ炭化フッ素系樹脂の穴より電極は４辺が１ｍｍづつ大きいため、電極周辺部は炭化フッ素系樹脂と重なりを持つように接合した。
【００３２】
この電極／高分子電解質膜接合体を、グラッシ−カ−ボン製のセパレ−タ−に組み込んで高分子電解質型燃料電池の単セルを構成した。高分子電解質型燃料電池は５０℃の電池温度で作動させ、アノ−ド側には６０℃で加湿した純水素を、カソ−ド側には４０℃で加湿した空気をそれぞれ大気圧で供給し、アノ−ド側の燃料利用率は、電流密度１０００ｍＡ／ｃｍ²のとき９５％となるよう水素流量を調整した。
【００３３】
本実験例に基づく高分子電解質型燃料電池の性能曲線６（図８では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池の性能曲線７（図８では、黒丸で表した）を図８に示す。図８より、本実験例により得られる高分子電解質型燃料電池は従来と同等の性能が得られることが確認された。
【００３４】
次に、本実験例に基づく高分子電解質型燃料電池のクロスリ−ク特性曲線８（図９では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池のクロスリ−ク特性曲線９（図９では、黒丸で表した）を図９に示す。このとき、高分子電解質型燃料電池は５０℃の電池温度で作動させ、カソ−ド側には４０℃で加湿した空気を大気圧で供給した。アノ−ド側は、出口を絞り、無加湿の純水素を所定の圧力で供給し、アノ−ド側とカソ−ド側に所定の差圧が発生するよう調整して、アノ−ド側にクロスリ−クした空気中の窒素量をガスクロマトグラフィ−で定量して、クロスリ−ク量を求めた。図９より、明らかに本実験例により得られた高分子電解質型燃料電池は、その性能が維持されたまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度が強くなり、耐差圧特性も向上することが確認された。試験後、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池を解体し調べたところ、電極周辺部、つまり電極と高分子電解質膜との界面近傍の高分子電解質膜が破れていることが判明した。
（実験例３）
本実験例は、本発明の高分子電解質型燃料電池の製造方法により、図４で述べた構成とほぼ対応した高分子電解質型燃料電池の単セルを製造する場合の例である。
【００３５】
高分子電解質として１６ｃｍ角に切断したデュポン社製のナフィオン１１２を用いた。この高分子電解質膜（図４の高分子電解質膜１に対応）の両方の面に、中心部１０ｃｍ角を切断して穴をあけた、１５ｃｍ角の炭化フッソ系樹脂製の粘着剤付きシ−ト（厚さ：３０μｍ、図４の炭化フッソ系樹脂の相２に対応）を張り付けた。アセチレンブラック系カ−ボン粉末に平均粒径約３０オングストロームの白金触媒を３０ｗｔ％担持した触媒担持カ−ボン粉末と、デュポン社製のナフィオン溶液を酢酸ブチル溶媒に分散し、ペ−スト状の電極触媒スラリ−を得た。この電極触媒スラリ−を、炭化フッ素系樹脂シ−ト付きの高分子電解質膜の両面にドクタ−ブレ−ド法により白金触媒量が０．３ｍｇ／ｃｍ²となるよう塗布した。このとき炭化フッ素系樹脂の中心部の１０ｃｍ角の穴の内側に高分子電解質膜と接するよう約４０μｍの厚みで塗布した。塗布した電極触媒スラリ−（図４の電極触媒層に対応）を粗乾燥後、１０．２ｃｍ角に切断した２枚の東レ製のカ−ボン不織布（図４のガス拡散相に対応）で炭化フッ素系樹脂シ−ト付きの高分子電解質膜を挟持し、１５０℃、５０ｋｇ／ｃｍ²でホットプレスして高分子電解質膜と電極を接合した。このとき炭化フッ素系樹脂シ−トの中心部の１０ｃｍ角の穴の部分にカ−ボン不織布がきて、高分子電解質膜と電極触媒スラリ−（電極触媒層）とカ−ボン不織布（ガス拡散層）とが接合し、かつ炭化フッ素系樹脂の穴よりカ−ボン不織布は４辺が１ｍｍづつ大きいため、カ−ボン不織布周辺部は炭化フッ素系樹脂と重なりを持つように接合した。また、電極触媒層は炭化フッ素系樹脂シ−トの厚みより若干厚めに塗布され、カ−ボン不織布とをホットプレスする際、電極触媒層の一部がカ−ボン不織布にめり込みながら、かつ均一に薄く高分子電解質膜と接合されているため、無駄な電極触媒層がカ−ボン不織布に存在することなく、効率的に電極反応に寄与するため、実質的に白金などの貴金属触媒の電極面積当たりの担持量を低減することができる。
【００３６】
この電極／高分子電解質膜接合体を、グラッシ−カ−ボン製のセパレ−タ−に組み込んで高分子電解質型燃料電池の単セルを構成した。高分子電解質型燃料電池は５０℃の電池温度で作動させ、アノ−ド側には６０℃で加湿した純水素を、カソ−ド側には４０℃で加湿した空気をそれぞれ大気圧で供給し、アノ−ド側の燃料利用率は、電流密度１０００ｍＡ／ｃｍ²のとき９５％となるよう水素流量を調整した。
【００３７】
本実験例に基づく高分子電解質型燃料電池の性能曲線６（図１０では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池の性能曲線７（図１０では、黒丸で表した）を図１０に示す。図１０より、本実験例の高分子電解質型燃料電池は従来と同等の性能が得られることを確認した。
【００３８】
次に、本実験例に基づく高分子電解質型燃料電池のクロスリ−ク特性曲線８（図１１では、白丸で表した）と、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池のクロスリ−ク特性曲線９（図１１では、黒丸で表した）を図１１に示す。このとき、高分子電解質型燃料電池は５０℃の電池温度で作動させ、カソ−ド側には４０℃で加湿した空気を大気圧で供給した。アノ−ド側は、出口を絞り、無加湿の純水素を所定の圧力で供給し、アノ−ド側とカソ−ド側に所定の差圧が発生するよう調整して、アノ−ド側にクロスリ−クした空気中の窒素量をガスクロマトグラフィ−で定量して、クロスリ−ク量を求めた。図１１より、明らかに本実験例の高分子電解質型燃料電池の性能を維持したまま、高分子電解質膜の機械的強度、特に電極周辺のエッジ部の機械的強度を強くし、耐差圧特性も向上することを確認した。試験後、比較のために従来法によって構成した炭化フッ素系樹脂による補強なしの高分子電解質型燃料電池を解体し調べたところ、電極周辺部、つまり電極と高分子電解質膜との界面近傍の高分子電解質膜が破れていることが判明した。
【００３９】
以上のように本発明は、高分子電解質と電極との接合面以外の電極周辺部の高分子電解質の少なくとも一方の面を炭化フッ素系樹脂で被覆することによって、または、高分子電解質と電極との接合面以外の電極周辺部の高分子電解質の少なくとも一方の面を炭化フッ素系樹脂で被覆し、炭化フッソ系樹脂で被覆されていない高分子電解質の中心部の面積より大きい電極を有して構成することによって、または、高分子電解質の少なくとも一方の面の周縁部に炭化フッソ系の樹脂を被覆し、炭化フッソ系樹脂で被覆した高分子電解質の中心部に炭化フッソ系樹脂と接する大きさの電極触媒層を被覆し、電極触媒層より大きいガス拡散相を電極触媒層と接するよう接合することによって、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度を強くすることが可能である。
【００４０】
【発明の効果】
以上述べたところから明らかなように、本発明の高分子電解質型燃料電池の製造方法は、高分子電解質のイオン伝導度を維持したまま、高分子電解質膜の機械的強度をより強く出来ると言う長所を有する。
【図面の簡単な説明】
【図１】本発明に関連する技術の高分子電解質型燃料電池の概略構成図である。
【図２】本発明に関連する技術の高分子電解質型燃料電池の概略構成図である。
【図３】本発明の高分子電解質型燃料電池の製造方法の一の実施の形態により得られる高分子電解質型燃料電池の概略構成図である。
【図４】本発明の高分子電解質型燃料電池の製造方法の他の実施の形態により得られる高分子電解質型燃料電池の概略構成図である。
【図５】本発明の高分子電解質型燃料電池の製造方法の他の実施の形態により得られる高分子電解質型燃料電池の概略構成図である。
【図６】本発明に関連する技術の高分子電解質型燃料電池の製造方法の実験例１の高分子電解質型燃料電池の特性図である。
【図７】本発明に関連する技術の高分子電解質型燃料電池の製造方法の実験例１の高分子電解質型燃料電池のクロスリ−ク特性図である。
【図８】本発明に関連する技術の高分子電解質型燃料電池の製造方法の実験例２の高分子電解質型燃料電池の特性図である。
【図９】本発明に関連する技術の高分子電解質型燃料電池の製造方法の実験例２の高分子電解質型燃料電池のクロスリ−ク特性図である。
【図１０】本発明の高分子電解質型燃料電池の製造方法の実験例３の高分子電解質型燃料電池の特性図である。
【図１１】本発明の高分子電解質型燃料電池の製造方法の実験例３の高分子電解質型燃料電池のクロスリ−ク特性図である。[0001]
The present invention relates to a polymer electrolyte fuel cell.PondIt relates to a manufacturing method.
[0002]
[Prior art]
A conventional polymer electrolyte fuel cell is composed of a carbonized fluorocarbon polymer electrolyte thin film as an electrolyte, anode and cathode electrodes, and a carbon or metal separator or cooling plate. It has been.
[0003]
The electrode and electrolyte that contribute to the battery reaction are composed of a mixture of carbon powder supporting a noble metal catalyst and a material equivalent to the electrolyte, and in some cases, a fluorocarbon compound-based water repellent is added. The mixture has been configured to be held in a carbon paper or the like made of carbon fiber and bonded to a polymer film as an electrolyte. Normally, the anode and cathode are composed of the same constituent materials, and when hydrogen-rich gas obtained by reforming hydrocarbon fuel is used as fuel, poisoning of the catalyst by carbon monoxide contained in the reformed gas. In order to suppress this, it has been considered to add a CO-resistant material such as ruthenium to the anode side only.
[0004]
The electrolyte is a fluorocarbon polymer containing a sulfone group, and is a proton-conductive electrolyte. In order to improve the performance of a fuel cell, it is one of the important factors to improve the ionic conductivity of the electrolyte, so it is usually necessary to reduce the internal resistance by reducing the thickness of the polymer electrolyte. Has been tried.
[0005]
[Problems to be solved by the invention]
However, the conventional polymer electrolyte fuel cell has a problem that the thinner the polymer electrolyte, the smaller the resistance of the electrolyte, but the lower the mechanical strength of the electrolyte membrane.
[0006]
  In consideration of such a problem of the conventional polymer electrolyte fuel cell, the present invention makes the mechanical strength of the polymer electrolyte stronger than before while maintaining the ionic conductivity of the polymer electrolyte substantially. Polymer electrolyte fuel cell that canPondAn object is to provide a manufacturing method.
[0010]
[Means for Solving the Problems]
  BookThe invention includes a polymer electrolyte, and an anode and a cathode as gas diffusion electrodes sandwiching the polymer electrolyte, and the anode and the cathode are carbons carrying an electrode catalyst. A method for producing a polymer electrolyte fuel cell comprising an electrode catalyst layer mainly comprising powder and a carbon powder or a gas diffusion phase mainly comprising carbon fiber not supporting the electrode catalyst. A resin coating step of coating a carbonized fluorocarbon resin in the vicinity of an outer peripheral portion of at least one surface of the polymer electrolyte; and after the resin coating step, coating with the carbonized fluorocarbon resin on the at least one surface An electrode catalyst layer forming step of forming an electrode catalyst layer having a size in contact with the inner peripheral edge of the carbonized fluororesin at substantially the center of the polymer electrolyte that has not been formed, and after the electrode catalyst layer forming step The electrode A bonding step and in which method for producing a polymer electrolyte fuel cell comprising a joining to the gas diffusion phase greater than medium layer in contact with the electrode catalyst layer.
[0011]
With such a configuration, for example, the mechanical strength of the polymer electrolyte membrane can be increased while maintaining the ionic conductivity of the polymer electrolyte.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the polymer electrolyte fuel cell according to the present invention will be described.Manufacturing method, and polymer electrolyte fuel cell of the technology related to the present invention and its manufacturing methodEmbodiments will be described with reference to the drawings.
[0013]
  FIG. 1 shows the present invention.Related technologyIt is an image figure for demonstrating the schematic structure of a polymer electrolyte fuel cell, and the structure and effect | action of this Embodiment are described using the figure.
[0014]
In FIG. 1, 1 is a polymer electrolyte membrane and 2 is a phase of carbonized fluororesin. The polymer electrolyte is usually a proton conductor having a film thickness of about 10 μm to 100 μm, and as described in the section of the problem to be solved by the invention, when the film thickness is reduced in order to reduce the resistance, the mechanical strength is increased. When the pressure is weakened and a differential pressure of the gas introduced between the anode side and the cathode side of the electrode 13 is generated, the electrolyte membrane is broken and cross leakage between the anode gas and the cathode gas is likely to occur. Here, the electrode 13 is provided on the polymer electrolyte membrane 1 shown in FIG. 1 at the position of a square hole in the center portion surrounded by the phase 2 of the fluorocarbon resin. Note that FIG. 1 omits the description of the electrode on one side of the anode and the cathode on the polymer electrolyte membrane 1.
[0015]
At this time, the mechanical strength of the portion of the electrolyte membrane sandwiched between the anode and the cathode is relatively strong, and the portion of the electrolyte membrane not joined to the electrode is almost always broken.
[0016]
Therefore, as in this embodiment, the ion conductivity of the polymer electrolyte is covered by coating at least one surface of the polymer electrolyte around the electrode other than the joint surface between the polymer electrolyte and the electrode with a fluorocarbon resin. It is possible to increase the mechanical strength of the polymer electrolyte membrane while maintaining the degree.
[0017]
The polymer electrolyte 1 is generally a fluorocarbon polymer containing a sulfone group. Therefore, the phase 2 of the fluorocarbon resin used for reinforcement may be the same fluorocarbon resin containing a sulfone group, but the fluorocarbon resin containing a sulfone group is expensive, so use Teflon or the like. However, it is cheaper and better.
[0018]
  Next, FIG. 2 shows the present invention.Other technology related toIt is an image figure for demonstrating the schematic structure of a polymer electrolyte fuel cell, and the structure and effect | action of this Embodiment are described using the figure.
[0019]
In FIG. 2, 1 is a polymer electrolyte membrane, 2 is a fluorocarbon resin phase, and 3 is an electrode. The polymer electrolyte is usually a proton conductor having a film thickness of about 10 μm to 100 μm. When the film thickness is reduced in order to reduce the resistance, the mechanical strength becomes weaker, and it is introduced into the anode side and the cathode side. When a differential pressure of gas or the like occurs, the electrolyte membrane is broken, and cross leakage between the anode gas and the cathode gas is likely to occur. At this time, the mechanical strength of the portion of the electrolyte membrane sandwiched between the anode and the cathode is relatively strong, and the portion of the electrolyte membrane not joined to the electrode is almost always broken. In particular, the electrolyte membrane is often broken at the edge portion around the electrode. Accordingly, at least one surface of the polymer electrolyte in the periphery of the electrode other than the joint surface between the polymer electrolyte 1 and the electrode 3 is coated with the fluorocarbon resin 2, and the polymer electrolyte not coated with the fluorocarbon resin is used. By having the electrode 3 larger than the area of the central portion, the mechanical strength of the polymer electrolyte membrane, particularly the edge strength around the electrode, is increased while maintaining the ionic conductivity of the polymer electrolyte. Is possible.
[0020]
  Next, FIG.A method for producing a polymer electrolyte fuel cellEmbodimentObtained byIt is an image figure for demonstrating the schematic structure of a polymer electrolyte fuel cell, and the structure and effect | action of this Embodiment are described using the figure.
[0021]
In FIG. 3, 1 is a polymer electrolyte membrane, 2 is a fluorocarbon resin phase, 33 is a gas diffusion phase constituting part of the electrode, and 4 is an electrode catalyst layer constituting part of the electrode. The polymer electrolyte is usually a proton conductor having a film thickness of about 10 μm to 100 μm. When the film thickness is reduced in order to reduce the resistance, the mechanical strength becomes weaker, and it is introduced into the anode side and the cathode side. When a differential pressure of gas or the like occurs, the electrolyte membrane is broken, and cross leakage between the anode gas and the cathode gas is likely to occur. At this time, the mechanical strength of the portion of the electrolyte membrane sandwiched between the anode and the cathode is relatively strong, and the portion of the electrolyte membrane not joined to the electrode is almost always broken. In particular, the electrolyte membrane is often broken at the edge portion around the electrode. Therefore, the fluorocarbon resin 2 is coated on the periphery (near the outer periphery) of at least one surface of the polymer electrolyte 1, and the central portion of the polymer electrolyte covered with the carbonized fluororesin is in contact with the carbonized fluorine resin. By covering the electrode catalyst layer 4 having a size and joining the gas diffusion phase 33 larger than the electrode catalyst layer so as to be in contact with the electrode catalyst layer 4, the ionic conductivity of the polymer electrolyte is maintained while maintaining the polymer electrolyte membrane. It is possible to increase the mechanical strength, particularly the mechanical strength of the edge portion around the electrode.
[0022]
  Next, FIG. 4 shows the present invention.Production method of polymer electrolyte fuel cellOther embodimentsObtained byIt is an image figure for demonstrating the schematic structure of a polymer electrolyte fuel cell, and the structure and effect | action of this Embodiment are described using the figure.
[0023]
In FIG. 4, 1 is a polymer electrolyte membrane, 2 is a fluorocarbon resin phase, 33 is a gas diffusion phase constituting part of the electrode, and 4 is an electrode catalyst layer constituting part of the electrode. The polymer electrolyte is usually a proton conductor having a film thickness of about 10 μm to 100 μm. When the film thickness is reduced in order to reduce the resistance, the mechanical strength becomes weaker, and it is introduced into the anode side and the cathode side. When a differential pressure of gas or the like occurs, the electrolyte membrane is broken, and cross leakage between the anode gas and the cathode gas is likely to occur. At this time, the mechanical strength of the portion of the electrolyte membrane sandwiched between the anode and the cathode is relatively strong, and the portion of the electrolyte membrane not joined to the electrode is almost always broken. In particular, the electrolyte membrane is often broken at the edge portion around the electrode. Therefore, an electrode catalyst layer having a size that is in contact with the carbonized fluorine-based resin at the center of the polymer electrolyte coated with the carbonized fluorine-based resin 2 on the periphery of both surfaces of the polymer electrolyte 1 and coated with the carbonized fluorine-based resin. 4 and joining the gas diffusion phase 33 larger than the electrode catalyst layer so as to be in contact with the electrode catalyst layer, while maintaining the ionic conductivity of the polymer electrolyte, particularly the mechanical strength of the polymer electrolyte membrane, It is possible to increase the mechanical strength of the edge portion.
[0024]
  Next, FIG.Production method of polymer electrolyte fuel cellOther embodimentsObtained byIt is an image figure for demonstrating the schematic structure of a polymer electrolyte fuel cell, and the structure and effect | action of this Embodiment are described using the figure.
[0025]
In FIG. 5, 1 is a polymer electrolyte membrane, 2 is a phase of a fluorocarbon resin, 33 is a gas diffusion phase constituting a part of the electrode, 4 is an electrode catalyst layer constituting a part of the electrode, and 5 is a fuel. It is a gas manifold for supplying a certain hydrogen or air as an oxidizing material to an electrode. The polymer electrolyte is usually a proton conductor having a film thickness of about 10 μm to 100 μm. When the film thickness is reduced in order to reduce the resistance, the mechanical strength becomes weaker, and it is introduced into the anode side and the cathode side. When a differential pressure of gas or the like occurs, the electrolyte membrane is broken, and cross leakage between the anode gas and the cathode gas is likely to occur. At this time, the mechanical strength of the portion of the electrolyte membrane sandwiched between the anode and the cathode is relatively strong, and the portion of the electrolyte membrane not joined to the electrode is almost always broken. In particular, the electrolyte membrane is often broken at the edge portion around the electrode. Therefore, an electrode catalyst having a size in which the peripheral portion of both surfaces of the polymer electrolyte 1 is coated with a carbonized fluororesin 2 and the central portion of the polymer electrolyte coated with the carbonized fluororesin 2 is in contact with the carbonized fluororesin. By covering the layer 4 and joining the gas diffusion phase 33 larger than the electrode catalyst layer so as to be in contact with the electrode catalyst layer, the mechanical strength of the polymer electrolyte membrane, particularly the electrode, while maintaining the ionic conductivity of the polymer electrolyte is maintained. It is possible to increase the mechanical strength of the peripheral edge portion. At this time, the phase 2 of the fluorocarbon resin simultaneously serves as a gasket for gas sealing the peripheral portion of the gas manifold.
[0026]
  next,Specific experimental example(Including a case where a single cell of a polymer electrolyte fuel cell of the technology related to the present invention described above is manufactured)Is described with reference to the drawings, and at the same time, a method for producing a polymer electrolyte fuel cell of the present inventionofEmbodiments will also be described.
(Experimental example 1)
  This experimental example substantially corresponds to the configuration described in FIG.It is an example of the technology relevant to the present inventionPolymer electrolyte fuel cell single cellWhen manufacturingIt is an example.
[0027]
That is, in this experimental example, Nafion 112 (corresponding to the polymer electrolyte membrane 1 in FIG. 1) manufactured by DuPont was used as the polymer electrolyte. A catalyst-supported carbon powder in which a platinum catalyst having an average particle size of about 30 angstroms is supported on an acetylene black carbon powder and a Nafion solution manufactured by DuPont are dispersed in a butyl acetate solvent. A catalyst slurry was obtained. This electrode catalyst slurry was formed on one surface of a Toray carbon nonwoven fabric cut into 10 cm square, and the amount of platinum catalyst was 0.3 mg / cm with respect to the area of the carbon nonwoven fabric.²It was applied by a screen printing method to obtain an electrode (corresponding to the electrode 13 in FIG. 1). After roughly drying the electrocatalyst slurry applied to the carbon non-woven fabric, the central portion of the polymer electrolyte membrane is sandwiched between these two electrodes so that the coated surface is in contact with the polymer electrolyte membrane, and 150 ° C., 50 kg / cm²The polymer electrolyte membrane and the electrode were joined by hot pressing. An adhesive tape made of a fluorocarbon resin (width: 1 cm, thickness: 50 μm) is placed on one surface of the polymer electrolyte membrane at the periphery of the electrode of the joined electrode / polymer electrolyte membrane assembly. The polymer electrolyte membrane was reinforced so that there was no gap. That is, in this case, four tapes with pressure-sensitive adhesive are prepared and attached to the periphery of the electrode (corresponding to phase 2 of the fluorocarbon resin in FIG. 1).
[0028]
This electrode / polymer electrolyte membrane assembly was incorporated into a separator made of glassy carbon to constitute a single cell of a polymer electrolyte fuel cell. The polymer electrolyte fuel cell had a battery temperature of 50 ° C. In the anode side, pure hydrogen humidified at 60 ° C. is supplied to the cathode side, and air humidified at 40 ° C. is supplied to the cathode side at atmospheric pressure. The fuel utilization rate on the anode side is the current Density 1000mA / cm²In this case, the hydrogen flow rate was adjusted to 95%.
[0029]
  A performance curve 6 of the polymer electrolyte fuel cell based on this experimental example (represented by white circles in FIG. 6), and a polymer electrolyte fuel cell without reinforcement with a fluorocarbon resin constructed by a conventional method for comparison The performance curve 7 (represented by black circles in FIG. 6) is shown in FIG. From this figure, this experimental exampleObtained byThe polymer electrolyte fuel cell should have the same performance as beforeButConfirmationIsIt was. The horizontal and vertical axes in FIG. 6 indicate current density and battery voltage, respectively.
[0030]
  Next, the cross-leak characteristic curve 8 (represented by white circles in FIG. 7) of the polymer electrolyte fuel cell based on this experimental example and the non-reinforcement by the fluorocarbon resin formed by the conventional method for comparison. FIG. 7 shows a cross leak characteristic curve 9 (represented by black circles in FIG. 7) of the polymer electrolyte fuel cell. At this time, the polymer electrolyte fuel cell was operated at a cell temperature of 50 ° C., and air humidified at 50 ° C. was supplied to the cathode side at atmospheric pressure. On the anode side, the outlet is throttled, non-humidified pure hydrogen is supplied at a predetermined pressure, and adjusted so that a predetermined differential pressure is generated between the anode side and the cathode side. The amount of nitrogen in the air that was cross-linked was quantified by gas chromatography to determine the amount of cross-leak. From this figure, clearly this experimental exampleIt is an example of the technology related to the present invention obtained byPolymer electrolyte fuel cellThePerformanceButMaintenanceWasThe mechanical strength of the polymer electrolyte membrane, especially the mechanical strength of the edge around the electrodeButstronglyBecomeImprove differential pressure resistanceButConfirmationIsIt was. After the test, for the purpose of comparison, a polymer electrolyte fuel cell that was not reinforced with a fluorocarbon resin constructed according to the conventional method was disassembled and examined, and it was found that the area around the electrode, that is, the area near the interface between the electrode and the polymer electrolyte membrane was high. It was found that the molecular electrolyte membrane was broken.
(Experimental example 2)
  This experimental example substantially corresponds to the configuration described in FIG.It is an example of the technology relevant to the present inventionPolymer electrolyte fuel cell single cellWhen manufacturingIt is an example.
[0031]
That is, Nafion 112 manufactured by DuPont (corresponding to the polymer electrolyte membrane 1 in FIG. 2) cut into a 16 cm square was used as the polymer electrolyte. An adhesive sheet made of a 15 cm square carbonized fluororesin resin (thickness: 50 μm, corresponding to phase 2 of the carbonized fluororesin resin in FIG. 1) having a hole formed by cutting a center 10 cm square, Affixed to one surface of the polymer electrolyte membrane. A catalyst-supported carbon powder in which a platinum catalyst having an average particle size of about 30 angstroms is supported on an acetylene black carbon powder and a Nafion solution manufactured by DuPont are dispersed in a butyl acetate solvent. A catalyst slurry was obtained. This electrode catalyst slurry was applied to one side of a Toray-made carbon nonwoven fabric cut into 10.2 cm square, and the amount of platinum catalyst was 0.3 mg / cm with respect to the area of the carbon nonwoven fabric.²Then, it was applied by a screen printing method to obtain an electrode (corresponding to the electrode 3 in FIG. 2). After roughly drying the electrocatalyst slurry applied to the carbon nonwoven fabric, the polymer electrolyte membrane with the fluorocarbon resin sheet is sandwiched between the two electrodes so that the coated surface is in contact with the polymer electrolyte membrane, and 150 ℃, 50kg / cm²The polymer electrolyte membrane and the electrode were joined by hot pressing. At this time, an electrode comes in a 10 cm square hole at the center of the fluorocarbon resin sheet, the polymer electrolyte membrane and the electrode are directly joined, and four sides of the electrode are 1 mm apart from the hole of the fluorocarbon resin. Because of its large size, the electrode periphery was joined so as to overlap with the fluorocarbon resin.
[0032]
This electrode / polymer electrolyte membrane assembly was incorporated into a separator made of glassy carbon to constitute a single cell of a polymer electrolyte fuel cell. The polymer electrolyte fuel cell is operated at a battery temperature of 50 ° C., pure hydrogen humidified at 60 ° C. is supplied to the anode side, and air humidified at 40 ° C. is supplied to the cathode side at atmospheric pressure. The fuel utilization on the anode side is a current density of 1000 mA / cm.²In this case, the hydrogen flow rate was adjusted to 95%.
[0033]
  A performance curve 6 of the polymer electrolyte fuel cell based on this experimental example (represented by white circles in FIG. 8) and a polymer electrolyte fuel cell without reinforcement by a fluorocarbon resin constructed by a conventional method for comparison The performance curve 7 (represented by black circles in FIG. 8) is shown in FIG. From FIG. 8, this experimental exampleMore obtainableThe polymer electrolyte fuel cell should have the same performance as beforeButConfirmationIsIt was.
[0034]
  Next, the cross leak characteristic curve 8 (represented by white circles in FIG. 9) of the polymer electrolyte fuel cell based on the present experimental example and the non-reinforcement by the fluorocarbon resin formed by the conventional method for comparison. FIG. 9 shows a cross leak characteristic curve 9 (represented by black circles in FIG. 9) of the polymer electrolyte fuel cell. At this time, the polymer electrolyte fuel cell was operated at a cell temperature of 50 ° C., and air humidified at 40 ° C. was supplied to the cathode side at atmospheric pressure. On the anode side, the outlet is throttled, non-humidified pure hydrogen is supplied at a predetermined pressure, and adjusted so that a predetermined differential pressure is generated between the anode side and the cathode side. The amount of nitrogen in the air that was cross-linked was quantified by gas chromatography to determine the amount of cross-leak. From FIG. 9, it is clear that this experimental exampleObtained byPolymer electrolyte fuel cellThePerformanceButMaintenanceWasThe mechanical strength of the polymer electrolyte membrane, especially the mechanical strength of the edge around the electrodeButstronglyBecomeImprove differential pressure resistanceButConfirmationIsIt was. After the test, for the purpose of comparison, a polymer electrolyte fuel cell that was not reinforced with a fluorocarbon resin constructed according to the conventional method was disassembled and examined, and it was found that the area around the electrode, that is, the interface near the electrode and the polymer electrolyte membrane It was found that the molecular electrolyte membrane was broken.
(Experimental example 3)
  This experimental exampleBy the method for producing a polymer electrolyte fuel cell of the present invention,A single cell of a polymer electrolyte fuel cell substantially corresponding to the configuration described in FIG.When manufacturingIt is an example.
[0035]
As a polymer electrolyte, Nafion 112 manufactured by DuPont, which was cut into 16 cm square, was used. A sheet with an adhesive made of 15 cm square fluorocarbon resin, in which a 10 cm square is cut in both sides of this polymer electrolyte membrane (corresponding to the polymer electrolyte membrane 1 in FIG. 4) (Thickness: 30 μm, corresponding to phase 2 of the fluorocarbon resin in FIG. 4). A catalyst-supported carbon powder in which a platinum catalyst having an average particle size of about 30 angstroms is supported on an acetylene black carbon powder and a Nafion solution manufactured by DuPont are dispersed in a butyl acetate solvent. A catalyst slurry was obtained. This electrocatalyst slurry was applied to both sides of a polymer electrolyte membrane with a fluorocarbon resin sheet so that the amount of platinum catalyst was 0.3 mg / cm by the doctor blade method.²It applied so that it might become. At this time, it was applied in a thickness of about 40 μm inside the 10 cm square hole at the center of the fluorocarbon resin so as to be in contact with the polymer electrolyte membrane. The coated electrode catalyst slurry (corresponding to the electrode catalyst layer in FIG. 4) is roughly dried and then carbonized with two Toray carbon nonwoven fabrics (corresponding to the gas diffusion phase in FIG. 4) cut to 10.2 cm square. A polymer electrolyte membrane with a fluorine resin sheet is sandwiched between 150 ° C. and 50 kg / cm.²The polymer electrolyte membrane and the electrode were joined by hot pressing. At this time, a carbon non-woven fabric comes into the 10 cm square hole at the center of the fluorocarbon resin sheet, and a polymer electrolyte membrane, an electrode catalyst slurry (electrode catalyst layer), and a carbon non-woven fabric (gas diffusion layer). ), And the carbon nonwoven fabric is 4 mm larger than the fluorocarbon resin holes by 1 mm, so the periphery of the carbon nonwoven fabric was bonded so as to overlap the fluorocarbon resin. In addition, the electrode catalyst layer is applied slightly thicker than the thickness of the fluorocarbon resin sheet, and when hot pressing the carbon nonwoven fabric, a part of the electrode catalyst layer is embedded in the carbon nonwoven fabric and is uniform. Since it is thinly bonded to the polymer electrolyte membrane, a wasteful electrode catalyst layer does not exist in the carbon nonwoven fabric and contributes to the electrode reaction efficiently. The amount of support per hit can be reduced.
[0036]
This electrode / polymer electrolyte membrane assembly was incorporated into a separator made of glassy carbon to constitute a single cell of a polymer electrolyte fuel cell. The polymer electrolyte fuel cell is operated at a battery temperature of 50 ° C., pure hydrogen humidified at 60 ° C. is supplied to the anode side, and air humidified at 40 ° C. is supplied to the cathode side at atmospheric pressure. The fuel utilization on the anode side is a current density of 1000 mA / cm.²In this case, the hydrogen flow rate was adjusted to 95%.
[0037]
The performance curve 6 of the polymer electrolyte fuel cell based on this experimental example (represented by white circles in FIG. 10) and a polymer electrolyte fuel cell without reinforcement by a fluorocarbon resin constructed by a conventional method for comparison The performance curve 7 (represented by black circles in FIG. 10) is shown in FIG. From FIG. 10, it was confirmed that the polymer electrolyte fuel cell of this experimental example can obtain the same performance as the conventional one.
[0038]
Next, the cross leak characteristic curve 8 (represented by white circles in FIG. 11) of the polymer electrolyte fuel cell based on the present experimental example and the non-reinforcing by the fluorocarbon resin constructed by the conventional method for comparison. FIG. 11 shows a cross leak characteristic curve 9 (represented by black circles in FIG. 11) of the polymer electrolyte fuel cell. At this time, the polymer electrolyte fuel cell was operated at a cell temperature of 50 ° C., and air humidified at 40 ° C. was supplied to the cathode side at atmospheric pressure. On the anode side, the outlet is throttled, non-humidified pure hydrogen is supplied at a predetermined pressure, and adjusted so that a predetermined differential pressure is generated between the anode side and the cathode side. The amount of nitrogen in the air that was cross-linked was quantified by gas chromatography to determine the amount of cross-leak. From FIG. 11, it is clear that the mechanical strength of the polymer electrolyte membrane, particularly the mechanical strength of the edge portion around the electrode, is increased while maintaining the performance of the polymer electrolyte fuel cell of this experimental example, and the differential pressure resistance characteristics Was also confirmed to improve. After the test, for the purpose of comparison, a polymer electrolyte fuel cell that was not reinforced with a fluorocarbon resin constructed according to the conventional method was disassembled and examined, and it was found that the area around the electrode, that is, the area near the interface between the electrode and the polymer electrolyte membrane was high. It was found that the molecular electrolyte membrane was broken.
[0039]
As described above, the present invention can be obtained by coating at least one surface of the polymer electrolyte in the peripheral portion of the electrode other than the joint surface between the polymer electrolyte and the electrode with a fluorocarbon resin, or the polymer electrolyte and the electrode. The surface of the polymer electrolyte in the periphery of the electrode other than the bonding surface is coated with a fluorocarbon resin and has an electrode larger than the area of the center of the polymer electrolyte not coated with the fluorocarbon resin. The size is such that at least one surface of the polymer electrolyte is coated with a carbonized fluoro resin and the center of the polymer electrolyte coated with the carbonized resin is in contact with the carbonized fluoro resin. The electrode catalyst layer is coated and a gas diffusion phase larger than the electrode catalyst layer is joined so as to be in contact with the electrode catalyst layer, thereby maintaining the ionic conductivity of the polymer electrolyte. It is possible to increase the mechanical strength of the film.
[0040]
【The invention's effect】
  As you can see from the above,The present inventionFor manufacturing polymer electrolyte fuel cellHas the advantage that the mechanical strength of the polymer electrolyte membrane can be increased while maintaining the ionic conductivity of the polymer electrolyte.
[Brief description of the drawings]
FIG. 1 shows the present invention.Related to polymer electrolyte fuel cellsFIG.
FIG. 2 shows the present invention.Related to polymer electrolyte fuel cellsFIG.
FIG. 3 of the present inventionA method for producing a polymer electrolyte fuel cellEmbodimentPolymer electrolyte fuel cell obtained byFIG.
FIG. 4 of the present inventionProduction method of polymer electrolyte fuel cellOther embodimentsPolymer electrolyte fuel cell obtained byFIG.
FIG. 5 shows the present invention.Production method of polymer electrolyte fuel cellOther embodimentsPolymer electrolyte fuel cell obtained byFIG.
FIG. 6Of polymer electrolyte fuel cell manufacturing method of technology related to2 is a characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 1. FIG.
FIG. 7Of polymer electrolyte fuel cell manufacturing method of technology related to2 is a cross-leak characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 1. FIG.
FIG. 8Of polymer electrolyte fuel cell manufacturing method of technology related to6 is a characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 2. FIG.
FIG. 9Of polymer electrolyte fuel cell manufacturing method of technology related to6 is a cross-leak characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 2. FIG.
FIG. 10 shows the present invention.Of manufacturing method of polymer electrolyte fuel cell6 is a characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 3. FIG.
FIG. 11 shows the present invention.Of manufacturing method of polymer electrolyte fuel cell6 is a cross-leak characteristic diagram of a polymer electrolyte fuel cell of Experimental Example 3. FIG.

Claims

A polymer electrolyte, and an anode and a cathode as gas diffusion electrodes for sandwiching the polymer electrolyte, and the anode and the cathode are mainly composed of carbon powder supporting an electrode catalyst. A method for producing a polymer electrolyte fuel cell comprising: an electrode catalyst layer comprising: and a gas diffusion phase mainly composed of carbon powder or carbon fiber not supporting the electrode catalyst,
A resin coating step of coating a fluorocarbon resin near the outer peripheral portion of at least one surface of the polymer electrolyte;
After the resin coating step, an electrode having a size in contact with an inner peripheral end of the carbonized fluororesin at a substantially central portion of the polymer electrolyte not coated with the carbonized fluororesin on the at least one surface An electrode catalyst layer forming step of forming a catalyst layer;
After the electrode catalyst layer forming step, a bonding step of bonding a gas diffusion phase larger than the electrode catalyst layer so as to contact the electrode catalyst layer;
A method for producing a polymer electrolyte fuel cell, comprising: