JP2004327105A - Fuel cell and method for designing same - Google Patents

Fuel cell and method for designing same Download PDF

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Publication number
JP2004327105A
JP2004327105A JP2003116639A JP2003116639A JP2004327105A JP 2004327105 A JP2004327105 A JP 2004327105A JP 2003116639 A JP2003116639 A JP 2003116639A JP 2003116639 A JP2003116639 A JP 2003116639A JP 2004327105 A JP2004327105 A JP 2004327105A
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joined body
current collector
fuel cell
spacer
electrolyte
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JP4661026B2 (en
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Takeshi Ichimura
健 市村
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Sony Corp
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Sony 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

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell for improving a power generation efficiency by increasing a real contact area between a catalyst layer and an electrolyte of a junction, and a method for designing the same for increasing the real contact area between the catalyst layer and the electrolyte of the junction. <P>SOLUTION: A pressure is applied by fastening a housing disposed outside the junction, and the pressure is dispersed to be transmitted to the junction by disposing a spacer between the housing and the junction. A pressure distribution becomes uniform by dispersing the pressure applied to the junction by the spacer to be transmitted to the junction, so that the real contact area of the interface between the electrolyte and a current collector is increased. By the area where the electrolyte and the current collector are really contacted being enlarged, a power generating reaction gets easy to occur and the power generation efficiency of the fuel cell is increased. An improvement of the efficiency is estimated by modeling the housing, the junction and the spacer and simulating a stress distribution applied to the junction when the pressure is applied to the housing by a contact structural analysis in a finite element method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料電池および燃料電池の設計方法に関するものである。
【０００２】
【従来の技術】
燃料電池は、例えば水素ガス（燃料ガス）と空気に含まれる酸素（酸化剤ガス）を電気化学的に反応させることにより発電を行う発電素子である。燃料電池は、発電により生成される生成物が水であることから環境を汚染することがない発電素子として近年注目されており、例えば自動車を駆動するための駆動電源として使用する試みが行われている。
【０００３】
さらに、上述の自動車駆動用の駆動電源に止まらず、例えばノート型パソコン、携帯電話及びＰＤＡなどの携帯型電子機器の駆動電源としての燃料電池の開発も活発に行われている。このような燃料電池においては、所要の電力を安定して出力できるとともに、携帯可能なサイズ及び重量とされることが重要となり、このような要求に対応するべく各種技術開発が盛んに行われている。
【０００４】
燃料電池は、電解質の違い等により様々なタイプのものに分類されるが、代表的なものに、電解質に固体高分子電解質を用いた燃料電池が知られている。固体高分子電解質型燃料電池は、低コスト化が可能で、小型化、軽量化も容易であり、電池性能の点でも高い出力密度を有することから、例えば上記の用途に有望である。また、複数の発電セルとセパレータを交互に積層することにより構成するスタックセル型の燃料電池も提案されている。
【０００５】
【発明が解決しようとする課題】
従来の燃料電池を用いた発電システムでは、図１５に示すように、電解質１と集電体２，３を組み合わせた接合体４を外側から筐体５，６で包み込んでパッケージ化した燃料電池を用いているものがある。このようなパッケージでは、筐体５，６内部に配置される接合体４や燃料流路板７、空気流路板８等の部材が分離しないように、筐体５，６をボルト９によって締結している。しかし、筐体５，６を締結することができる位置は接合体４が配置された領域外に限定され、筐体５，６の外周近辺でのみ締結を行うことになる。
【０００６】
一方、接合体４での発電は、燃料流路板７に形成された燃料流路１２から集電体２が燃料を受け取り、空気流路板８に形成された空気流路１３から集電体３が空気を受け取ることで行われる。一般に集電体２，３の電解質１と接触する面にはそれぞれ触媒層１０，１１が形成されており、触媒層１０，１１と電解質１の接触部分で発電反応が起きる。しかし、触媒層１０，１１と電解質１の界面は微小な凹凸が存在し、微視的には図１６に示すように触媒層１０，１１と電解質１とが現実に接触している面積（真実接触面積１４）が存在する。
【０００７】
筐体５，６の外周近辺でのみ締結を行った場合には、電解質１と触媒層１０，１１との界面に働く応力は、締結部分に近い部分に強くはたらき、締結部分から離れるに従って緩和される分布になっていると推測され、電解質１の周縁部は触媒層１０，１１と強く接触し、接合体４の面中心に向かって応力が緩和してゆくことになる。つまり電解質１と触媒層１０，１１の界面の密着性が面全体で均一ではないと考えられ、触媒反応の効率が悪化したり電気抵抗が悪化して、燃料電池全体での発電効率が悪化する原因であると考えられる。
【０００８】
したがって本願発明は、接合体の触媒層と電解質との真実接触面積を増加させて発電効率の向上を図ることが可能な燃料電池と、接合体の触媒層と電解質との真実接触面積を増加させる燃料電池の設計方法を提供することを課題とする。
【０００９】
【課題を解決するための手段】
上記課題を解決するために本願発明の燃料電池は、燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体と、前記筐体と前記接合体との間に配置されて前記締結部からの圧力を分散させて前記接合体に伝えるスペーサとを有することを特徴とする。
【００１０】
締結部に加えられた圧力をスペーサによって分散して接合体に伝えることにより、接合体に加わる圧力分布が均一なものになり、接合体の電解質と集電体とが均一に接触し電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。
【００１１】
発電効率をより向上させるためには、スペーサによって接合体に伝えられる圧力が接合体に略均一に加えられることが望ましい。また、燃料電極集電体および酸素電極集電体の電解質に接する面に触媒層が形成し、集電体と電解質との界面に触媒層を存在させることも重要である。
【００１２】
スペーサは、筐体から加えられる圧力を受ける受圧部と、接合体に圧力を加える加圧部と、受圧部と加圧部との間で力を伝達する伝達部とを有するとし、受圧部が他の部材と接触する面の面積より、加圧部が他の部材と接触する面の面積を大きくすることや、加圧部が接合体の略全面に接触することによって、スペーサが圧力の分散を図ることができる。また、スペーサは平板に開口部が複数形成された網目形状とすることや、スペーサを屈曲した板状で面の中央部分が接合体に対して凸に湾曲させることによっても、スペーサが圧力の分散を図ることができる。
【００１３】
スペーサを接合体に隣接して配置することで、接合体に加わる圧力を効率的にスペーサが分散することができる。このとき、スペーサを多孔質材料により形成することで、多孔質材料の孔部を介して接合体への燃料や酸素の供給を行うことが可能である。また、スペーサと接合体とを接着するための接着層を、スペーサと接合体との間に設けるとしてもよい。
【００１４】
また、上記課題を解決するために本願発明の燃料電池は、燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体とを有し、前記燃料電極集電体または前記酸素電極集電体が前記締結部からの圧力を分散して、前記燃料電極集電体または前記酸素電極集電体と前記電解質とが接触する圧力を均一にすることを特徴とする。
【００１５】
締結部から加えられる圧力を集電体が分散することにより、集電体と電解質との間に加わる圧力分布が均一になり、電解質と集電体とが均一に接触して電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。
【００１６】
燃料電極集電体または酸素電極集電体として、表面積の異なる二枚の板状部材を重ね合わせることや、面の中央部分が電解質に対して凸に形成された湾曲した板状とすることによって、締結部に加えられた圧力を集電体が分散することができる。
【００１７】
また、上記課題を解決するために本願発明の燃料電池は、燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体とを有し、前記筐体は、中央部分が前記接合体に対して凸に形成されて湾曲した一対の板状部材を締結することにより構成されることを特徴とする。
【００１８】
筐体が湾曲した板状部材であり、中央部が接合体に対して凸とされていることにより、筐体を締結することで接合体に加えられる圧力が分散され、接合体に加わる圧力分布が均一なものになり、接合体の電解質と集電体とが均一に接触し電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。
【００１９】
このとき、締結部において、板状部材の主面に垂直方向に押圧力を加え筐体を締結するとしても、板状部材の主面に水平方向に押圧力を加えて筐体を締結するとしても、接合体に加わる圧力は分散されることになる。
【００２０】
また、上記課題を解決するために本願発明の燃料電池の設計方法は、燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、前記接合体の外部に配される筐体と、前記筐体と前記電解質との間に配置されるスペーサとをモデル化する手順と、前記筐体に圧力を加えた際に前記接合体に加わる応力分布をシミュレーションする手順と、前記応力分布において応力が閾値以上である面積の割合を求める手順とを有することを特徴とする。
【００２１】
筐体と接合体とスペーサとをモデル化して応力分布のシミュレーションを行うことで、実際に燃料電池を作成する前の段階で応力分布を見積もることができ、応力分布を均一にするのに適したスペーサ形状や筐体の締結方法を知ることができる。接合体に加わる応力分布が均一な燃料電池では発電効率の向上を図ることができるため、発電効率を向上させるための燃料電池の設計を簡便に行うこと可能になる。このとき、応力分布のシミュレーションに、有限要素法による接触構造解析を用いることができる。
【００２２】
【発明の実施の形態】
以下、本願発明を適用した燃料電池および燃料電池の設計方法について、図面を参照しながら詳細に説明する。なお本願発明は、以下の記述に限定されるものではなく、本発明の要旨を逸脱しない範囲において適宜変更可能である。
【００２３】
図１は本発明の燃料電池パッケージの構成を示す分解斜視図である。電解質２１と集電体２２，２３を組み合わせた接合体２４をスペーサ３２，３３で挟みこみ、スペーサ３２，３３の外側にそれぞれ燃料流路板２７、空気流路板２８を配置し、これらの部材を外側から筐体２５，２６で包み込んで燃料電池をパッケージ化する。このとき、筐体２５，２６内部に配置される接合体２４や、燃料流路板２７、空気流路板２８、スペーサ３２，３３等の部材が分離しないように、筐体２５，２６をボルト２９によって締結している。筐体２５，２６を締結する位置は接合体２４が配置された領域外であり、筐体２５，２６の外周近辺でのみ締結を行う。
【００２４】
電解質２１は、プロトンを透過させるイオン透過性と耐酸化性、耐熱性を兼ね備えた材質で形成された膜であり、例えばパーフルオロスルホン酸ポリマーを用いる。
【００２５】
集電体２２，２３は、発生する起電力を取り出すための電極材であり、金属材料や炭素材料、導電性を有する不織布などを用いて構成される。この集電体２２，２３で電解質２１を挟み込んで接合体２４が構成される。炭素系材料を用いる場合は、炭素系材料の多孔質表面に白金などの触媒を担持させるようにしても良く、集電体２２，２３の電解質２１と接触する面にはそれぞれ触媒層３０，３１が形成されており、触媒層３０，３１と電解質２１の接触部分で発電反応が起きる。触媒層３０，３１は、電解質２１と集電体２２，２３の界面での化学反応を促進する材質を用い、例えば本発明では炭素繊維膜上に白金が担持された炭素粒子を設けた構造としている。
【００２６】
筐体２５，２６は矩形状の平板部材であり、外周近辺にはボルト２９を通す締結孔３４が形成されている。筐体２５，２６は接合体２４、スペーサ３２，３３、燃料流路板２７および空気流路板２８よりも外形が大きく、締結孔３４にボルト２９を通して筐体２５，２６を締結した場合にも、ボルト２９が他の部材に干渉しない。また、筐体２５，２６はボルト２９の締結によって各部材に対して押圧力を加えるための部材であり、ボルト２９のネジ締めによって簡単に変形してしまわない程度の剛性を有する材質によって形成され、本実施の形態では例えばアルミニウムを用いている。
【００２７】
燃料流路板２７は、複数の溝である燃料流路３５が形成された板状の部材であり、燃料流路３５が集電体２２方向に向くように配置されている。また空気流路板２８は、複数の溝である空気流路３６が形成された板状の部材であり、空気流路３６が集電体２３方向に向くように配置されている。燃料流路３５と空気流路３６の溝方向は互いに直角となるように配置され、燃料流路３５には燃料電池外部から供給される燃料ガスが流され、空気流路３６には燃料電池外部から供給される酸素を含んだ空気が流される。
【００２８】
スペーサ３２，３３は集電体２２，２３の略全面に接する板状の部材であり、集電体２２と燃料流路板２７との間にスペーサ３２が配され、集電体２３と空気流路板２８との間にスペーサ３３が配されている。燃料流路３５および空気流路３６を流れる燃料ガスと酸素を集電体２２，２３に供給する必要が有るため、スペーサ３２，３３には開口部３７が形成され、気体を透過させることが可能となっている。スペーサ３２，３３を多孔質な材質で形成してスペーサ３２，３３の内部を燃料ガスおよび酸素が流れるようにしてもよい。スペーサ３２，３３は、燃料流路板２７と空気流路板２８とから伝えられた押圧力が接合体２４に対して均一に加わるように、面の一部に加えられた押圧力を分散する機能を有している。押圧力を分散して伝達するためには、スペーサ３２，３３はある程度の剛性を有する材質によって形成される必要がある。
【００２９】
接合体２４での発電は、燃料流路板２７に形成された燃料流路３５からスペーサ３２を介して集電体２２が燃料を受け取り、空気流路板２８に形成された空気流路３６からスペーサ３３を介して集電体２３が空気を受け取り、接合体２４においてＨ２→２Ｈ＋＋２ｅ−の如き反応と１／２Ｏ２＋２Ｈ＋＋２ｅ−＝Ｈ２Ｏの如き反応が起こり、結果として水が生成される。水素ガス（Ｈ２）が燃料流路３５を通過する間にプロトンを発生させ、解離したプロトン（Ｈ＋）は集電体２２から集電体２３に向かって電解質２１の膜中を移動する。この移動したプロトンは、集電体２３の触媒層３１付近で酸素（空気）と反応して、これにより所望の起電力が取り出される。
【００３０】
図１では、各部材の配置関係を明示するために図示を省略しているが、筐体２５，２６の内部に配置される各部材の周囲と筐体２５，２６の間には、気密を保持するための気密部材が配置されており、燃料流路３５および空気流路３６からの燃料ガスや酸素が漏洩しない構造となっている。
【００３１】
筐体２５，２６の締結は、筐体２５，２６の外周近辺に形成された締結孔３４でのボルト２９の締結により行われる。このため、筐体２５，２６がある程度の剛性を有する材質で形成されていたとしても、燃料流路板２７および空気流路板２８に加わる押圧力の分布は外周近辺が大きく中心付近が小さい圧力となってしまう。しかし、燃料流路板２７および空気流路板２８に加わった圧力はスペーサ３２，３３に伝達され、スペーサ３２，３３の主として外周付近に押圧力が加わったとしても、スペーサ３２，３３が剛性を有する材質で形成されていることから、スペーサ３２，３３の面全体が接合体２４に押圧力を伝えることになる。
【００３２】
したがって、スペーサ３２，３３が接合体２４に隣接して配されていることによって、接合体２４の中心付近に加わる圧力を大きくすることができる。また、スペーサ３２，３３が集電体２２，２３の略全面に接するため、接合体２４に加わる押圧力の分布を接合体２４の全面に均一なものに近づけることができる。
【００３３】
接合体２４に加わる押圧力の分布が均一なものに近づくと、触媒層３０，３１と電解質２１との界面に存在する真実接触面積が大きくなり、発電反応が起こる面積が増加するために燃料電池の発電効率が向上するはずである。そこで、スペーサを配置した燃料電池と、スペーサを配置しない燃料電池を作成して出力電流値と出力電圧値を測定するとともに、接合体に加わる応力分布をコンピュータによってシュミレーションし、接合体に加わる応力の分布と発電効率との関係を調べることにする。
【００３４】
図２（ａ）は比較例１としてのスペーサを配置しない燃料電池の構成を示した分解図であり、図２（ｂ）は実施例１としてのスペーサを配置した燃料電池の構成を示した分解図である。比較例１と実施例１ともに、同一の構成要素には同一の符号を付して説明する。比較例１および実施例１ともに、電解質４１を集電体４２と集電体４３で挟み込んで接合体４４が形成されている。また、筐体４５と燃料流路板４７が略同一の形状に形成されて接合され、燃料流路板４７の集電体４２と接する面には燃料流路５５が形成されている。筐体４５と燃料流路板４７は外周部分が枠形状を成しており、燃料電池の気密を確保する気密部材としても機能する。
【００３５】
図２（ｂ）に示した実施例１においては、集電体４２と燃料流路板４７との間および集電体４３と図示していない空気流路板との間にスペーサ５３が配されている。スペーサ５３は、樹脂によって形成された格子形状の平板な板状部材であり、外形は集電体４２，４３よりも小さく、格子形状であるために開口部分を燃料ガスや酸素が通過可能となっている。ここでは、格子形状の平板部材をスペーサ形状の例として示したが、平板状の部材に開口部を複数設けて網目状の部材を形成するとしても良い。また、スペーサ５３と集電体４２，４３との間に接着層を形成し、スペーサ５３と集電体４２，４３との密着性を向上させて接合体４４に均一に圧力を伝達するとしてもよい。
【００３６】
さらに、比較例１および実施例１ともに、図１に示したように空気流路が形成された空気流路板と筐体とによって接合体４４を挟み込む構造を持つが、図２では図示を省略している。筐体４５と燃料流路板４７および図示していない筐体と空気流路板の外周部分には締結孔５４が形成されており、筐体４５と図示していない筐体とを対向させて締結孔５４をボルト等で締め付けることで接合体４４に対して押圧力が加えられる。
【００３７】
上述したスペーサを配置しない比較例１の燃料電池と、スペーサを配置した実施例１の燃料電池とを、同一形状、同一材質、同一サイズで形成し、ボルトを同一の推力で締結したとして、コンピュータを用いて有限要素法を用いて燃料電池の構造を数値モデル化し、接触構造解析を行って接合体４４に加わる応力の分布をシミュレーションした。
【００３８】
図３は、スペーサを配置しない比較例１における接合体の応力分布のシミュレーション結果を示す図である。図では応力が０．０〜０．６ｋｇｆ／ｍｍ２の範囲を示している。また、図中で黒色が濃い領域は応力が０．１ｇｆ／ｍｍ２以下の領域である。図から明らかなように、筐体の締結が外周部分で行われているために、接合体４４に加わる応力は接合体４４の外周近辺に集中しており、接合体４４の中央付近では応力が低くなっている。図３での応力が０．１ｋｇｆ／ｍｍ２以上の領域の面積は、接合体４４の全面積の３６．０％であった。
【００３９】
図４は、スペーサを配置する実施例１における接合体の応力分布のシミュレーション結果を示す図である。図では応力が０．０〜０．６ｋｇｆ／ｍｍ２の範囲を示している。また、図中で黒色が濃い領域は応力が０．１ｇｆ／ｍｍ２以下の領域である。図から明らかなように、スペーサ５３を接合体４４に隣接して配置したことにより、筐体の締結を外周部分で行っていても、接合体４４に加わる応力は外周近辺に集中せずに接合体４４の中央付近でも応力が大きく加わっている。図４での応力が０．１ｋｇｆ／ｍｍ２以上の領域の面積は、接合体４４の全面積の６８．４％であった。
【００４０】
次に、図２（ａ）に示したスペーサを配置しない比較例１と、図２（ｂ）に示したスペーサを配置した実施例１の燃料電池に、同一流量の水素ガスと酸素を供給して実際に発電反応を行わせて、出力電圧と出力電流の関係を測定した。図５は燃料電池の発電による出力電流値と出力電圧値をグラフに示した特性図である。図中で黒塗りの四角で示したグラフがスペーサを配置しない比較例１での出力を示したものであり、黒塗りの三角で示したグラフがスペーサを配置した実施例１での出力を示したものである。
【００４１】
図３から明らかなように、実施例１と比較例１とを同一の出力電圧値で比較した場合には、スペーサを配置した実施例１のほうが出力電流値が大きく、電力値が大きいことが分かる。例えば、図中に太線で示した出力電圧値が６００ｍＶでは、図中破線で示したように、比較例１の出力電流値は２８．６ｍＡであり、実施例１の出力電流値は３８．１ｍＡであった。したがって、スペーサを配置したことによって発電効率は約３３％向上したことがわかる。
【００４２】
図３および図４に示したシミュレーションによる応力分布での応力が０．１ｋｇｆ／ｍｍ２以上の面積比率は、比較例１で３６．０％であり実施例１で６８．４％であったことから、スペーサを配置したことによる接合体４４に加わる応力０．１ｋｇｆ／ｍｍ２以上の面積が３２．４％増加したことが分かる。応力分布でのある一定値以上の面積比率の増加が、実測による発電効率の向上とほぼ同程度であることから、発電効率の向上は応力分布の均一化に起因するものであることがわかる。
【００４３】
接合体に加わる応力分布を均一化することにより、電解質と触媒層とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００４４】
また、コンピュータを用いて有限要素法により接触構造解析を行い、接合体に加わる応力分布をシミュレーションすることにより、スペーサや筐体などの燃料電池を構成する部材の形状や材質形状を変化させた場合にも、応力分布を計算することが可能である。これにより、実際に燃料電池を形成する前にシミュレーションによって接合体に加わる応力分布を計算し、応力が一定値以上の領域面積比を計算することによって、燃料電池の発電効率を予測することが可能となる。計算によって燃料電池の発電効率の向上をある程度予測することができるために、燃料電池の開発速度を向上させることが可能である。
【００４５】
次に、燃料電池の設計に際してコンピュータを用いて有限要素法による接触構造解析を行って、スペーサの形状ごとに接合体に加わる応力分布を計算して、発電効率の向上を予測した例を示す。以下の実施の形態で示すシミュレーションでは、筐体と燃料流路板または空気流路板とが一体に形成されたとして、筐体とスペーサと接合体との関係だけを示して計算を行うが、燃料電池の構成は図１に示したものと同様であるとする。
【００４６】
図６にスペーサを配置しない場合の燃料電池の構成を比較例２として、図６（ａ）に断面図を示し、シミュレーションにより得られた各部材の変形を図６（ｂ）に示している。比較例２は、縦横の辺の長さが３０ｍｍ×７０ｍｍの矩形状の接合体６１と、接合体６１に隣接して配置する筐体６２で構成される燃料電池である。比較例２においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００４７】
シミュレーションモデルとして、接合体６１の電解質をポリエチレンナフタレートであるとし、筐体６２をアルミニウムとした場合の材料物性値を用いて、有限要素法による接触構造解析で各部材の変形量を計算した。図６（ｂ）には、長手方向の辺に形成された締結部６３に集中荷重を行い、接合体６１の面方向に対して垂直に締結を行った場合での、接合体６１と筐体６２との変形を計算した結果を示している。図６（ｂ）から明らかなように、筐体６２の長手方向の辺に形成された締結部６３でのみ締結を行ったことにより、接合体６１および筐体６２の中央部分が接合体６１が配された側と反対に凸形状に変形してしまうことが分かる。
【００４８】
図７に比較例２での接合体６１での応力分布を計算した結果を示す。図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図から明らかなように、接合体６１に加わる応力は締結部６３周辺が特に大きく、それより遠ざかるにつれて緩和されている。
【００４９】
上述した実施例１で説明したように、接合体６１に加わる応力が一定値以上の領域を増加させることによって、接合体６１での触媒層と電解質との真実接触面積を増加させて、燃料電池の発電効率を向上させることができる。したがって、図６に示した比較例２の筐体６２と接合体６１との間にスペーサを挿入して、筐体６２から接合体６１に伝達される押圧力をスペーサによって分散させた場合にも、有限要素法による接触構造解析を用いたシミュレーションによって応力分布の変化を計算することで、燃料電池の発電効率向上を予測することが可能である。
【００５０】
図８は実施例２であり、スペーサを配置した場合の燃料電池の構成を図８（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図８（ｂ）に示している。実施例２は、縦横の辺の長さが３０ｍｍ×７０ｍｍの矩形状の接合体７１と、接合体７１に隣接して配置されるスペーサ７３と、スペーサ７３に隣接して配置される筐体７２で構成される燃料電池である。実施例２においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００５１】
スペーサ７３は、接合体７１と略同一の面積を有する矩形状の板状部材であり、中央部分が長手方向に沿って接合体７１方向に凸となるように屈曲されている。したがって、スペーサ７３は筐体７２方向に突出した受圧部７５と、中央部分が接合体７１方向に突出した加圧部７６と、受圧部７５と加圧部７６とを連結する伝達部７７とを有している。受圧部７５はスペーサ７３の長辺付近に形成された平面部分であり筐体７２と接している。加圧部７６はスペーサ７３の中央部分に形成された平面部分であり接合体７１と接している。受圧部７５と加圧部７６の面積は略同一である。加圧部７６が接合体７１と面接触するために、スペーサ７３は燃料ガスや酸素を透過するように多孔質な材料で形成することが望ましい。
【００５２】
スペーサ７３が筐体７２と接合体７１との間に配置されていることにより、筐体７２の長辺近傍に形成された締結部７４に押圧力を加えたとしても、スペーサ７３の受圧部７５が筐体７２から押圧力を受け、伝達部７７を介して加圧部７６が接合体７１に押圧力を伝達するため、接合体７１に加わる応力は締結部７４から分散されて接合体７１の中央部分にも加えられる。
【００５３】
スペーサを配置しない比較例２に対してのスペーサ７３の効果を確認するために、実施例２のシミュレーションモデルも比較例２と同様に、接合体７１の電解質をポリエチレンナフタレートであるとし、筐体７２をアルミニウムとした場合の材料物性値を用いる。また、筐体７２の長手方向の辺に形成された締結部７４に集中荷重を行い、接合体７１の面方向に対して垂直に締結を行ったとして、有限要素法による接触構造解析で計算した。
【００５４】
図８（ｂ）に示した実施例２での接合体７１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図８（ｂ）から明らかなように、スペーサ７３を筐体７２と接合体７１との間に挿入したことによって、スペーサ７３の伝達部７７が形成されている領域近辺での接合体７１に加わる応力が増加しているのが分かる。
【００５５】
したがって、スペーサ７３として屈曲した板状であり面の中央部分が接合体７１に対して凸に形成されているものを用いることによって、筐体７２に加えられた圧力をスペーサ７３が分散して接合体７１に伝達し、接合体７１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体７１に加わる応力分布を均一化することによって、接合体７１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００５６】
図９は実施例３であり、スペーサを配置した場合の燃料電池の構成を図９（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図９（ｂ）に示している。実施例３は、縦横の辺の長さが３０ｍｍ×７０ｍｍの矩形状の接合体８１と、接合体８１に隣接して配置されるスペーサ８３と、スペーサ８３に隣接して配置される筐体８２で構成される燃料電池である。実施例３においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００５７】
スペーサ８３は接合体８１と略同一の面積を有する矩形状の板状部材であり、長辺部分の筐体８２側に形成された受圧部８５と、接合体８１側に形成された加圧部８６と、受圧部８５と加圧部８６とを連結する伝達部８７とを有している。受圧部８５はスペーサ７３の長辺付近に形成された平面部分であり筐体８２と接している。加圧部８６はスペーサ８３の接合体８１側の全面に形成された平面部分であり接合体８１と接している。スペーサ８３の長辺部分は、長手方向に沿って受圧部８５と加圧部８６との二重構造を形成し、その二重構造の間には伝達部７７によって中空領域８８が形成されている。
【００５８】
受圧部８５の面積よりも加圧部８６の面積のほうが大きく、加圧部８６の全面が接合体８１と接触して圧力の伝達を行うため、接合体８１の略全面に圧力が均一に加えられる。加圧部８６が接合体８１と面接触するために、スペーサ８３は燃料ガスや酸素を透過するように多孔質な材料で形成することが望ましい。
【００５９】
スペーサ８３が筐体８２と接合体８１との間に配置されていることにより、筐体８２の長辺近傍に形成された締結部８４に押圧力を加えたとしても、スペーサ８３の受圧部８５が筐体８２から押圧力を受け、伝達部８７を介して加圧部８６が接合体８１に押圧力を伝達するため、接合体８１に加わる応力は締結部８４から分散されて接合体８１の略全面にわたって均一に加えられる。
【００６０】
スペーサを配置しない比較例２に対してのスペーサ８３の効果を確認するために、実施例３のシミュレーションモデルも比較例２と同様に、接合体８１の電解質をポリエチレンナフタレートであるとし、筐体８２をアルミニウムとした場合の材料物性値を用いる。また、筐体８２の長手方向の辺に形成された締結部８４に集中荷重を行い、接合体８１の面方向に対して垂直に締結を行ったとして、有限要素法による接触構造解析で計算した。
【００６１】
図９（ｂ）に示した実施例３での接合体８１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図９（ｂ）から明らかなように、スペーサ８３を筐体８２と接合体８１との間に挿入したことによって、スペーサ８３の伝達部８７が形成されている領域近辺での接合体８１に加わる応力が増加しているのが分かる。
【００６２】
したがって、スペーサ８３として受圧部８５と加圧部８６と伝達部８７とを有し、スペーサ８３の長辺部分が長手方向に沿って受圧部８５と加圧部８６との二重構造を形成し、加圧部８６が接合体８１の略全面と接するものを用いることによって、筐体８２に加えられた圧力をスペーサ８３が分散して接合体８１に伝達し、接合体８１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体８１に加わる応力分布を均一化することによって、接合体８１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００６３】
図１０は実施例４であり、スペーサを配置した場合の燃料電池の構成を図１０（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図１０（ｂ）に示している。実施例４は、縦横の辺の長さが３０ｍｍ×７０ｍｍの矩形状の接合体９１と、接合体９１に隣接して配置されるスペーサ９３と、スペーサ９３に隣接して配置される筐体９２で構成される燃料電池である。実施例４においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００６４】
スペーサ９３は、接合体９１と略同一の面積を有する矩形状の板状部材であり、筐体９２側に形成された受圧部９５と、接合体９１側に形成された加圧部９６と、受圧部９５と加圧部９６とを連結する伝達部９７とを有している。受圧部９５および加圧部９６は接合体９１と略同一の面積の平面部分であり、受圧部９５と加圧部９６との二重構造を形成し、その二重構造の間には伝達部９７によって中空領域９８が形成されている。
【００６５】
受圧部９５と加圧部９６の面積は同一であり、受圧部９５の全面が筐体９２と接触し、加圧部９６の略全面が接合体９１と接触して圧力の伝達を行うため、接合体９１の略全面に圧力が均一に加えられる。加圧部９６が接合体９１と面接触するために、スペーサ９３は燃料ガスや酸素を透過するように多孔質な材料で形成することが望ましい。
【００６６】
スペーサ９３が筐体９２と接合体９１との間に配置されていることにより、筐体９２の長辺近傍に形成された締結部９４に押圧力を加えたとしても、スペーサ９３の受圧部９５が筐体９２から押圧力を受け、伝達部９７を介して加圧部９６が接合体９１に押圧力を伝達するため、接合体９１に加わる応力は締結部９４から分散されて接合体９１の略全面にわたって均一に加えられる。
【００６７】
スペーサを配置しない比較例２に対してのスペーサ９３の効果を確認するために、実施例４のシミュレーションモデルも比較例２と同様に、接合体９１の電解質をポリエチレンナフタレートであるとし、筐体９２をアルミニウムとした場合の材料物性値を用いる。また、筐体９２の長手方向の辺に形成された締結部９４に集中荷重を行い、接合体９１の面方向に対して垂直に締結を行ったとして、有限要素法による接触構造解析で計算した。
【００６８】
図１０（ｂ）に示した実施例４での接合体９１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図１０（ｂ）から明らかなように、スペーサ９３を筐体９２と接合体９１との間に挿入したことによって、接合体９１のほぼ全面に加わる応力が増加しているのが分かる。
【００６９】
したがって、スペーサ９３として受圧部９５と加圧部９６と伝達部９７とを有し、受圧部９５と加圧部９６とが接合体９１と略同一面積のの二重構造を形成し、加圧部９６が接合体９１の略全面と接するものを用いることによって、筐体９２に加えられた圧力をスペーサ９３が分散して接合体９１に伝達し、接合体９１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体９１に加わる応力分布を均一化することによって、接合体９１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００７０】
図１１は実施例５であり、筐体を湾曲させて接合体に加わる応力の分散を図った場合の燃料電池の構成を図１１（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図１１（ｂ）に示している。実施例５は、縦横の辺の長さが３０ｍｍ×７０ｍｍの矩形状の接合体１０１と、接合体１０１に隣接して配置される筐体１０２で構成される燃料電池である。実施例５においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００７１】
筐体１０２は接合体１０１と略同一サイズの板状の部材であり、中央部分が接合体１０１方向に凸に湾曲した形状を成している。ここで湾曲の形状としては筐体１０２の全面が一様な曲率で湾曲しているとしてもよく、ボルトなどで締結を行う締結部１０４周辺部分を平面形状にするとしてもよい。本実施例は、図６（ｂ）に示したように、平板の筐体を締結すると筐体は中央部分が接合体と反対側に膨らむ傾向があるため、その傾向と逆に予め筐体１０２を接合体１０１方向に膨らませて、接合体１０１に加わる応力分布の均一化を図ったものである。
【００７２】
筐体１０２が接合体１０１に対して凸に湾曲した形状であり、筐体１０２の長辺近傍に形成された締結部１０４に押圧力を加えた場合には、筐体１０２と接合体１０１とは筐体１０２の突出した部分から接触し始める。締結部１０４に加えられる押圧力は、筐体１０２が変形して接合体１０１と全面にわたって接触するまで加えられる。このため、締結部１０４から接合体１０１に伝達される押圧力は接合体１０１の中央部分に分散されて、接合体１０１の略全面にわたって均一に加えられる。
【００７３】
筐体が平坦な板状部材である比較例２に対しての筐体１０２の湾曲の効果を確認するために、実施例５のシミュレーションモデルも比較例２と同様に、接合体１０１の電解質をポリエチレンナフタレートであるとし、筐体１０２をアルミニウムとした場合の材料物性値を用いる。また、筐体１０２の長手方向の辺に形成された締結部１０４に集中荷重を行い、接合体１０１の面方向に対して垂直に締結を行ったとして、有限要素法による接触構造解析で計算した。
【００７４】
図１１（ｂ）に示した実施例５での接合体１０１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図１１（ｂ）から明らかなように、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とすることによって、接合体１０１の中央部分に加わる応力が増加しているのが分かる。
【００７５】
したがって、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とすることによって、締結部１０４に加えられた押圧力を筐体１０２の湾曲部分が分散して接合体１０１に伝達し、接合体１０１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体１０１に加わる応力分布を均一化することによって、接合体１０１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００７６】
図１２は、実施例６として第五の実施の形態と同様に、筐体の中央部分を接合体方向に凸に湾曲させ、接合体に加わる応力の分散を図った場合の燃料電池の構成を図１２（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図１２（ｂ）に示している。第五の実施の形態との相違点は、筐体に加える押圧力を接合体の面に平行に加える点であり、燃料電池のシミュレーションに用いる構造は第五の実施の形態と同様であるために同一の符号を用いて説明を行う。
【００７７】
図１２（ｂ）に示した実施例６での接合体１０１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図１２（ｂ）から明らかなように、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とし、筐体１０２の長辺に形成された締結部１０５において、接合体１０１の面に平行方向に押圧力を加えることによって、接合体１０１の中央部分に加わる応力が増加しているのが分かる。
【００７８】
したがって、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とし、接合体１０１の面に平行方向に押圧力を加えることによって、締結部１０５に加えられた押圧力を筐体１０２の湾曲部分が分散して接合体１０１に伝達し、接合体１０１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体１０１に加わる応力分布を均一化することによって、接合体１０１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００７９】
図１３は実施例７として、第五の実施の形態と同様に、筐体の中央部分を接合体方向に凸に湾曲させ、接合体に加わる応力の分散を図った場合の燃料電池の構成を図１３（ａ）に断面図で示し、接合体に加わる応力分布のシミュレーション結果を図１３（ｂ）に示している。第五の実施の形態との相違点は、筐体に加える押圧力を接合体の面に平行方向と垂直方向に加える点であり、燃料電池のシミュレーションに用いる構造は第五の実施の形態と同様であるために同一の符号を用いて説明を行う。
【００８０】
図１３（ｂ）に示した実施例７での接合体１０１に加わる応力分布を計算した結果では、図中で濃い黒色で示された領域は応力が小さい領域であり、薄い黒色で示された領域は応力が大きい領域である。図１３（ｂ）から明らかなように、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とし、筐体１０２の長辺に形成された締結部１０５において接合体１０１の面に平行方向に押圧力を加えるとともに、筐体１０２の長辺近傍に形成された締結部１０４において接合体１０１の面に垂直方向に押圧力を加えることによって、接合体１０１の中央部分および長辺近傍に加わる応力が増加しているのが分かる。
【００８１】
したがって、筐体１０２の中央部分を接合体１０１方向に凸な湾曲形状とし、接合体１０１の面に平行方向および垂直方向に押圧力を加えることによって、締結部１０５に加えられた押圧力を筐体１０２の湾曲部分が分散して接合体１０１に伝達し、接合体１０１に加わる応力分布の均一化を図ることができる。上述した第一の実施の形態で説明したように、接合体１０１に加わる応力分布を均一化することによって、接合体１０１の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００８２】
本実施の形態では、接合体を構成する集電体を加工することで筐体に加えられる押圧力を分散して、接合体の触媒層と電解質との真実接触面積を増加させる。図１４に集電体を加工して接合体を形成した燃料電池の構成例を示す。本実施の形態においても筐体と空気流路板または燃料流路板とを一体として形成したとしている。
【００８３】
図１４（ａ）は、電解質１１１に集電体１１２，１１３を形成して接合体を構成し、筐体１１４の長辺近傍に形成された締結部１１５において、電解質１１１の面に垂直方向に押圧力を加える様子を示した断面図である。電解質１１１と接触して配される集電体１１２は電解質１１１と略同一サイズであり、電解質１１１と集電体１１２とは互いに略全面にわたって接触している。集電体１１３は、集電体１１２よりも小さく形成されて集電体１１２に隣接して中央部分に配されている。
【００８４】
筐体１１４は平板な部材であるため、締結部１１５に押圧力を加えた場合には図６（ｂ）に示したように中央部分が接合体と反対側に膨らんでしまう。そこで、接合体を構成する集電体を大小二枚の部材を重ね合わせた形状とすることによって、電解質１１１と集電体１１２の中央部分に加わる応力が増加するようにしたものである。
【００８５】
図１４（ｂ）は、中央が電解質１２１方向に凸に湾曲した集電体１２２と電解質１２１とによって接合体を構成し、筐体１２４の長辺近傍に形成された締結部１２５において、電解質１２１の面に垂直方向に押圧力を加える様子を示した断面図である。電解質１２１に隣接して配される集電体１２２は電解質１２１と略同一サイズであり、中央部分が電解質１２１方向に凸に湾曲した形状となっている。
【００８６】
筐体１２４は平板な部材であるため、締結部１２５に押圧力を加えた場合には図６（ｂ）に示したように中央部分が接合体と反対側に膨らんでしまう。そこで、接合体を構成する集電体１２２の中央部分を電解質１２１方向に凸に湾曲した形状とすることによって、電解質１２１と集電体１２２の中央部分に加わる応力が増加するようにしたものである。
【００８７】
図１４（ａ）に示した大小二枚の集電体を重ね合わせた場合にも、図１４（ｂ）に示した集電体の中央を電解質方向に凸に湾曲させた場合にも、筐体の長辺近傍に加えられた押圧力は集電体によって分散され、電解質と集電体の中央部分での応力を増加させると考えられる。接合体に加わる応力分布を均一化することによって、接合体の触媒層と電解質とを密着させて触媒利用面積を増加させることや、接合体内部の接触抵抗を低減させることや、拡散層としての集電体での空隙性が一様となり、燃料の安定した拡散を維持し、出力の向上を図ることができる。
【００８８】
【発明の効果】
締結部に加えられた圧力をスペーサによって分散して接合体に伝えることにより、接合体に加わる圧力分布が均一なものになり、接合体の電解質と集電体とが均一に接触し電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。
【００８９】
スペーサを、筐体から加えられる圧力を受ける受圧部と、接合体に圧力を加える加圧部と、受圧部と加圧部との間で力を伝達する伝達部とを有するとし、受圧部が他の部材と接触する面の面積より、加圧部が他の部材と接触する面の面積を大きくすることや、加圧部が接合体の略全面に接触することによって、スペーサが圧力の分散を図ることができる。
【００９０】
筐体を湾曲した板状部材であり、中央部が接合体に対して凸とすることにより、筐体を締結することで接合体に加えられる圧力が分散され、接合体に加わる圧力分布が均一なものになり、接合体の電解質と集電体とが均一に接触し電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。このとき、締結部において板状部材の主面に垂直方向に押圧力を加え筐体を締結するとしても、板状部材の主面に水平方向に押圧力を加えて筐体を締結するとしても、接合体に加わる圧力は分散されることになる。
【００９１】
締結部から加えられる圧力を集電体が分散することにより、集電体と電解質に加わる圧力分布が均一なものになり、電解質と集電体とが均一に接触し電解質と集電体の界面の真実接触面積が増加する。電解質と集電体とが実際に接触する面積が広がることにより、発電反応が起こり易くなって燃料電池の発電効率が向上する。燃料電極集電体または酸素電極集電体として、表面積の異なる二枚の板状部材を重ね合わせることや、面の中央部分が電解質に対して凸に形成された湾曲した板状とすることによって、集電体が圧力を分散することができる。
【００９２】
筐体と接合体とスペーサとをモデル化して応力分布のシミュレーションを行うことで、実際に燃料電池を作成する前の段階で応力分布を見積もることができ、応力分布を均一にするのに適したスペーサ形状や筐体の締結方法を知ることができる。接合体に加わる応力分布が均一な燃料電池では発電効率の向上を図ることができるため、発電効率を向上させるための燃料電池の設計を簡便に行うこと可能になる。
【図面の簡単な説明】
【図１】本発明の燃料電池の構成を示す分解斜視図である。
【図２】本発明の第一の実施の形態で用いた燃料電池の分解図であり、図２（ａ）はスペーサを配置しない比較例１を示し、図２（ｂ）は格子状のスペーサを配置した実施例１を示している。
【図３】シミュレーションによって計算したスペーサを配置しない比較例１での接合体に加わる応力分布を示す図である。
【図４】シミュレーションによって計算したスペーサを配置した実施例１での接合体に加わる応力分布を示す図である。
【図５】比較例１と実施例１を用いて発電を行ったときの出力電流値と出力電圧値を示すグラフである。
【図６】燃料電池を簡素化して筐体と接合体でモデル化した場合でのスペーサを配置しない比較例２を示す図であり、図６（ａ）は断面図であり、図６（ｂ）はシミュレーションによって筐体と接合体の変形を計算した結果を示す図である。
【図７】シミュレーションによって、スペーサを配置しない比較例２での接合体に加わる応力分布を示す図である。
【図８】スペーサを筐体と接合体の間に配置した実施例２を示す図であり、図８（ａ）は断面図であり、図８（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図９】スペーサを筐体と接合体の間に配置した実施例３を示す図であり、図９（ａ）は断面図であり、図９（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図１０】スペーサを筐体と接合体の間に配置した実施例４を示す図であり、図１０（ａ）は断面図であり、図１０（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図１１】筐体を湾曲させて圧力の分散を図った実施例５を示す図であり、図１１（ａ）は断面図であり、図１１（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図１２】筐体を湾曲させて圧力の分散を図った実施例６を示す図であり、図１２（ａ）は断面図であり、図１２（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図１３】筐体を湾曲させて圧力の分散を図った実施例７を示す図であり、図１３（ａ）は断面図であり、図１３（ｂ）はシミュレーションによって接合体に加わる応力分布を計算した結果を示す図である。
【図１４】実施例８として接合体の集電体を加工することによって圧力の分散を図ったものであり、図１４（ａ）は大小の集電体を重ね合わせた例を示し、図１４（ｂ）は集電体を湾曲させた例を示す。
【図１５】従来の燃料電池の構成を示す分解斜視図である。
【図１６】触媒層と電解質との接触する界面での微視的構造を示す模式図である。
【符号の説明】
１，２１，４１，１１１，１２１ 電解質
２，３，２２，２３，４２，４３，１１２，１１３，１２２ 集電体
４，２４，４４，６１，７１，８１，９１，１０１ 接合体
５，６，２５，２６，４５，６２，７２，８２，９２，１０２，１１４，１２４筐体
７，２７，４７ 燃料流路板
８，２８ 空気流路板
９，２９ ボルト
１０，１１，３０，３１ 触媒層
１２，３５，５５ 燃料流路
１３，３６ 空気流路
１４ 真実接触面積
３２，３３，５３，７３，８３，９３ スペーサ
３４，５４ 締結孔
３７ 開口部
６３，７４，８４，９４，１０４，１０５，１１５，１２５ 締結部
７５，８５，９５ 受圧部
７６，８６，９６ 加圧部
７７，８７，９７ 伝達部
８８，９８ 中空領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell and a method for designing a fuel cell.
[0002]
[Prior art]
A fuel cell is a power generation element that generates power by electrochemically reacting, for example, hydrogen gas (fuel gas) and oxygen (oxidant gas) contained in air. Fuel cells have attracted attention in recent years as power generating elements that do not pollute the environment because the product generated by power generation is water.For example, attempts have been made to use them as drive power sources for driving automobiles. I have.
[0003]
Further, fuel cells are being actively developed as a drive power source for not only the above-described drive power source for driving a car but also a portable electronic device such as a notebook personal computer, a mobile phone, and a PDA. In such a fuel cell, it is important to be able to stably output required electric power and to have a portable size and weight, and various technologies have been actively developed to meet such demands. I have.
[0004]
Fuel cells are classified into various types according to differences in electrolytes and the like. As a typical example, a fuel cell using a solid polymer electrolyte as an electrolyte is known. The polymer electrolyte fuel cell is promising for, for example, the above applications because it can be reduced in cost, can be easily reduced in size and weight, and has a high output density in terms of battery performance. Also, a stack cell type fuel cell configured by alternately stacking a plurality of power generation cells and separators has been proposed.
[0005]
[Problems to be solved by the invention]
In a conventional power generation system using a fuel cell, as shown in FIG. 15, a fuel cell in which a joined body 4 in which an electrolyte 1 and current collectors 2 and 3 are combined is wrapped in a casing 5 and 6 from the outside and packaged. Some are used. In such a package, the casings 5 and 6 are fastened with bolts 9 so that members such as the joined body 4, the fuel passage plate 7, and the air passage plate 8 disposed inside the casings 5 and 6 are not separated. are doing. However, the position where the casings 5 and 6 can be fastened is limited to the outside of the region where the joined body 4 is arranged, and the fastening is performed only near the outer periphery of the casings 5 and 6.
[0006]
On the other hand, in the power generation in the joined body 4, the current collector 2 receives the fuel from the fuel flow channel 12 formed in the fuel flow channel plate 7, and receives the fuel from the air flow channel 13 formed in the air flow channel plate 8. 3 by receiving air. Generally, catalyst layers 10 and 11 are formed on the surfaces of the current collectors 2 and 3 that are in contact with the electrolyte 1, respectively, and a power generation reaction occurs at a contact portion between the catalyst layers 10 and 11 and the electrolyte 1. However, the interface between the catalyst layers 10, 11 and the electrolyte 1 has minute irregularities, and microscopically, as shown in FIG. 16, the area where the catalyst layers 10, 11 and the electrolyte 1 are actually in contact (the truth). There is a contact area 14).
[0007]
When fastening is performed only in the vicinity of the outer periphery of the housings 5 and 6, the stress acting on the interface between the electrolyte 1 and the catalyst layers 10 and 11 strongly acts on the portion close to the fastening portion, and is relaxed as the distance from the fastening portion increases. It is presumed that the distribution is such that the peripheral portion of the electrolyte 1 comes into strong contact with the catalyst layers 10 and 11, and the stress is reduced toward the center of the surface of the joined body 4. That is, it is considered that the adhesion between the interface between the electrolyte 1 and the catalyst layers 10 and 11 is not uniform over the entire surface, and the efficiency of the catalytic reaction is deteriorated, the electric resistance is deteriorated, and the power generation efficiency of the entire fuel cell is deteriorated. Probable cause.
[0008]
Therefore, the present invention provides a fuel cell capable of improving the power generation efficiency by increasing the real contact area between the catalyst layer of the joined body and the electrolyte, and increasing the real contact area between the catalyst layer of the joined body and the electrolyte. It is an object to provide a method for designing a fuel cell.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a fuel cell according to the present invention includes a joined body in which an electrolyte is sandwiched between a fuel electrode current collector and an oxygen electrode current collector; And a spacer disposed between the housing and the joined body to disperse pressure from the fastening portion and transmit the pressure to the joined body.
[0010]
By distributing the pressure applied to the fastening part by the spacer and transmitting it to the joined body, the pressure distribution applied to the joined body becomes uniform, and the electrolyte of the joined body and the current collector come into uniform contact with each other to collect the electrolyte. The real contact area at the interface of the conductor increases. By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved.
[0011]
In order to further improve the power generation efficiency, it is desirable that the pressure transmitted to the joined body by the spacer is applied to the joined body substantially uniformly. It is also important that a catalyst layer be formed on the surface of the fuel electrode current collector and the oxygen electrode current collector that is in contact with the electrolyte, and that the catalyst layer be present at the interface between the current collector and the electrolyte.
[0012]
The spacer has a pressure receiving portion that receives pressure applied from the housing, a pressure portion that applies pressure to the joined body, and a transmission portion that transmits a force between the pressure receiving portion and the pressure portion. By increasing the area of the surface where the pressurized portion contacts other members than the area of the surface that contacts other members, or by the pressurized portion contacting almost the entire surface of the joined body, the spacer can reduce the pressure. Dispersion can be achieved. In addition, the spacer can disperse the pressure by forming the spacer into a mesh shape in which a plurality of openings are formed in a flat plate, or by bending the spacer in a plate-like shape and bending the central portion of the surface convexly with respect to the joined body. Can be achieved.
[0013]
By disposing the spacer adjacent to the joined body, the pressure applied to the joined body can be efficiently dispersed by the spacer. At this time, by forming the spacer from a porous material, it is possible to supply fuel or oxygen to the joined body through the holes of the porous material. Further, an adhesive layer for bonding the spacer and the joined body may be provided between the spacer and the joined body.
[0014]
According to another aspect of the present invention, there is provided a fuel cell including a fuel cell current collector and an oxygen electrode current collector sandwiching an electrolyte between the fuel cell current collector and the oxygen electrode current collector. And a casing having a fastening portion for applying pressure to the fuel electrode current collector or the oxygen electrode electrode, the fuel electrode current collector or the oxygen electrode current collector dispersing the pressure from the fastening portion, and the fuel electrode current collector or the oxygen electrode The pressure at which the current collector contacts the electrolyte is made uniform.
[0015]
By dispersing the pressure applied from the fastening portion by the current collector, the distribution of pressure applied between the current collector and the electrolyte becomes uniform, and the electrolyte and the current collector come into uniform contact, so that the electrolyte and the current collector The real contact area of the interface increases. By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved.
[0016]
By stacking two plate-shaped members with different surface areas as a fuel electrode current collector or an oxygen electrode current collector, or by forming a curved plate shape with the central part of the surface protruding against the electrolyte The current collector can disperse the pressure applied to the fastening portion.
[0017]
According to another aspect of the present invention, there is provided a fuel cell including a fuel cell current collector and an oxygen electrode current collector sandwiching an electrolyte between the fuel cell current collector and the oxygen electrode current collector. A housing having a fastening portion for applying pressure to the housing, wherein the housing is configured by fastening a pair of curved plate-shaped members having a central portion formed to be convex with respect to the joined body. It is characterized.
[0018]
The casing is a curved plate-shaped member, and the central portion is convex with respect to the joined body, so that the pressure applied to the joined body by fastening the casing is dispersed, and the pressure distribution applied to the joined body Is uniform, and the electrolyte of the joined body and the current collector are in uniform contact, and the real contact area at the interface between the electrolyte and the current collector is increased. By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved.
[0019]
At this time, in the fastening portion, even if the housing is fastened by applying a pressing force in the vertical direction to the main surface of the plate member, it is assumed that the housing is fastened by applying a pressing force in the horizontal direction to the main surface of the plate member. However, the pressure applied to the joined body is dispersed.
[0020]
Further, in order to solve the above-mentioned problem, a fuel cell designing method of the present invention includes a joined body in which an electrolyte is sandwiched between a fuel electrode current collector and an oxygen electrode current collector, and a joint disposed outside the joined body. Case, a procedure for modeling a spacer disposed between the case and the electrolyte, and a procedure for simulating a stress distribution applied to the joined body when pressure is applied to the case, Calculating a ratio of an area in which the stress is equal to or larger than a threshold in the stress distribution.
[0021]
By simulating the stress distribution by modeling the housing, the joined body, and the spacer, the stress distribution can be estimated before the fuel cell is actually created, which is suitable for making the stress distribution uniform. It is possible to know the spacer shape and the method of fastening the housing. In a fuel cell in which the distribution of stress applied to the joined body is uniform, the power generation efficiency can be improved, so that it is possible to easily design a fuel cell for improving the power generation efficiency. At this time, the contact structure analysis by the finite element method can be used for the simulation of the stress distribution.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a fuel cell and a fuel cell designing method to which the present invention is applied will be described in detail with reference to the drawings. Note that the present invention is not limited to the following description, and can be appropriately changed without departing from the spirit of the present invention.
[0023]
FIG. 1 is an exploded perspective view showing the configuration of the fuel cell package of the present invention. A joined body 24 in which the electrolyte 21 and the current collectors 22 and 23 are combined is sandwiched between spacers 32 and 33, and a fuel channel plate 27 and an air channel plate 28 are arranged outside the spacers 32 and 33, respectively. Is wrapped in the housings 25 and 26 from the outside to package the fuel cell. At this time, the casings 25 and 26 are bolted so that members such as the joined body 24 disposed inside the casings 25 and 26, the fuel passage plate 27, the air passage plate 28, and the spacers 32 and 33 are not separated. 29. The position where the casings 25 and 26 are fastened is outside the region where the joined body 24 is arranged, and fastening is performed only near the outer periphery of the casings 25 and 26.
[0024]
The electrolyte 21 is a membrane formed of a material having both ion permeability for transmitting protons, oxidation resistance, and heat resistance. For example, a perfluorosulfonic acid polymer is used.
[0025]
The current collectors 22 and 23 are electrode materials for extracting the generated electromotive force, and are formed using a metal material, a carbon material, a conductive nonwoven fabric, or the like. A joined body 24 is formed by sandwiching the electrolyte 21 between the current collectors 22 and 23. When a carbon-based material is used, a catalyst such as platinum may be supported on the porous surface of the carbon-based material, and the catalyst layers 30 and 31 are respectively provided on the surfaces of the current collectors 22 and 23 that are in contact with the electrolyte 21. Are formed, and a power generation reaction occurs at a contact portion between the catalyst layers 30 and 31 and the electrolyte 21. The catalyst layers 30 and 31 are made of a material that promotes a chemical reaction at the interface between the electrolyte 21 and the current collectors 22 and 23. For example, in the present invention, the catalyst layers 30 and 31 have a structure in which carbon particles carrying platinum on a carbon fiber membrane are provided. I have.
[0026]
The housings 25 and 26 are rectangular flat plate members, and a fastening hole 34 for passing the bolt 29 is formed near the outer periphery. The housings 25 and 26 have a larger outer shape than the joined body 24, the spacers 32 and 33, the fuel passage plate 27, and the air passage plate 28. Even when the housings 25 and 26 are fastened through the bolts 29 through the fastening holes 34, , The bolt 29 does not interfere with other members. Further, the housings 25 and 26 are members for applying a pressing force to each member by fastening the bolt 29, and are formed of a material having such a rigidity that it is not easily deformed by screwing the bolt 29. In the present embodiment, for example, aluminum is used.
[0027]
The fuel passage plate 27 is a plate-shaped member in which a plurality of grooves, that is, a fuel passage 35 is formed, and is arranged so that the fuel passage 35 faces the current collector 22 direction. The air flow path plate 28 is a plate-shaped member in which an air flow path 36 that is a plurality of grooves is formed, and is arranged so that the air flow path 36 faces the current collector 23. The groove directions of the fuel flow path 35 and the air flow path 36 are arranged so as to be perpendicular to each other, a fuel gas supplied from outside the fuel cell flows through the fuel flow path 35, and a fuel gas outside the fuel cell flows through the air flow path 36. The air containing oxygen supplied from is supplied.
[0028]
The spacers 32 and 33 are plate-shaped members that are in contact with substantially the entire surfaces of the current collectors 22 and 23. The spacers 32 are disposed between the current collector 22 and the fuel passage plate 27, and the current collectors 23 and the air flow A spacer 33 is arranged between the base plate 28 and the road plate 28. Since it is necessary to supply the fuel gas and oxygen flowing through the fuel flow path 35 and the air flow path 36 to the current collectors 22 and 23, openings 37 are formed in the spacers 32 and 33 so that the gas can pass therethrough. It has become. The spacers 32 and 33 may be formed of a porous material so that the fuel gas and oxygen flow inside the spacers 32 and 33. The spacers 32 and 33 disperse the pressing force applied to a part of the surface so that the pressing force transmitted from the fuel passage plate 27 and the air passage plate 28 is uniformly applied to the joined body 24. Has functions. In order to transmit the pressing force in a dispersed manner, the spacers 32 and 33 need to be formed of a material having a certain degree of rigidity.
[0029]
In the power generation in the joined body 24, the current collector 22 receives the fuel from the fuel flow path 35 formed in the fuel flow path plate 27 via the spacer 32 and receives the fuel from the air flow path 36 formed in the air flow path plate 28. The current collector 23 receives the air through the spacer 33 and the H 2 → 2H + + 2e − Reaction and 1 / 2O 2 + 2H + + 2e − = H 2 A reaction such as O occurs, resulting in the production of water. Hydrogen gas (H 2 ) Generate protons while passing through the fuel channel 35, and dissociated protons (H + ) Moves in the membrane of the electrolyte 21 from the current collector 22 to the current collector 23. The transferred protons react with oxygen (air) in the vicinity of the catalyst layer 31 of the current collector 23, thereby extracting a desired electromotive force.
[0030]
Although illustration is omitted in FIG. 1 in order to clarify the arrangement relationship of each member, airtightness is provided between the periphery of each member arranged inside the housings 25 and 26 and the housings 25 and 26. An airtight member for holding is arranged, and the structure is such that fuel gas and oxygen do not leak from the fuel flow path 35 and the air flow path 36.
[0031]
The housings 25 and 26 are fastened by fastening bolts 29 in fastening holes 34 formed near the outer periphery of the housings 25 and 26. For this reason, even if the housings 25 and 26 are formed of a material having a certain degree of rigidity, the distribution of the pressing force applied to the fuel passage plate 27 and the air passage plate 28 is such that the pressure is large near the outer periphery and small near the center. Will be. However, the pressure applied to the fuel flow path plate 27 and the air flow path plate 28 is transmitted to the spacers 32, 33, and the rigidity of the spacers 32, 33 increases even if a pressing force is applied mainly to the outer periphery of the spacers 32, 33. The spacers 32 and 33 transmit the pressing force to the joined body 24 because the spacers 32 and 33 are formed of a material having the same.
[0032]
Therefore, since the spacers 32 and 33 are arranged adjacent to the joined body 24, the pressure applied to the vicinity of the center of the joined body 24 can be increased. Further, since the spacers 32 and 33 are in contact with substantially the entire surfaces of the current collectors 22 and 23, the distribution of the pressing force applied to the joined body 24 can be made uniform over the entire surface of the joined body 24.
[0033]
When the distribution of the pressing force applied to the joined body 24 approaches a uniform one, the real contact area existing at the interface between the catalyst layers 30 and 31 and the electrolyte 21 increases, and the area where the power generation reaction occurs increases, so that the fuel cell Power generation efficiency should be improved. Therefore, a fuel cell with spacers and a fuel cell without spacers were created, the output current value and the output voltage value were measured, and the stress distribution applied to the joined body was simulated by a computer to reduce the stress applied to the joined body. Let us examine the relationship between distribution and power generation efficiency.
[0034]
FIG. 2A is an exploded view showing a configuration of a fuel cell without a spacer as Comparative Example 1, and FIG. 2B is an exploded view showing a configuration of a fuel cell with a spacer as Example 1. FIG. In both Comparative Example 1 and Example 1, the same components will be described with the same reference numerals. In both Comparative Example 1 and Example 1, the joined body 44 is formed by sandwiching the electrolyte 41 between the current collector 42 and the current collector 43. The casing 45 and the fuel passage plate 47 are formed and joined in substantially the same shape, and a fuel passage 55 is formed on a surface of the fuel passage plate 47 that contacts the current collector 42. The casing 45 and the fuel passage plate 47 have a frame shape at the outer peripheral portion, and also function as an airtight member for ensuring the airtightness of the fuel cell.
[0035]
In the first embodiment shown in FIG. 2B, spacers 53 are provided between the current collector 42 and the fuel flow path plate 47 and between the current collector 43 and the air flow path plate (not shown). ing. The spacer 53 is a grid-shaped flat plate-shaped member formed of a resin, and has an outer shape smaller than the current collectors 42 and 43. Since the spacer 53 has a grid shape, fuel gas and oxygen can pass through the opening. ing. Here, the lattice-shaped plate member is shown as an example of the spacer shape, but a mesh-shaped member may be formed by providing a plurality of openings in the plate-shaped member. Further, even if an adhesive layer is formed between the spacer 53 and the current collectors 42 and 43 to improve the adhesion between the spacer 53 and the current collectors 42 and 43 and transmit pressure uniformly to the joined body 44. Good.
[0036]
Further, both the comparative example 1 and the example 1 have a structure in which the joined body 44 is sandwiched between the housing and the air flow path plate in which the air flow path is formed as shown in FIG. 1, but not shown in FIG. are doing. A fastening hole 54 is formed in the outer periphery of the housing 45 and the fuel passage plate 47 and the outer periphery of the not-shown housing and the air passage plate, and the housing 45 and the not-shown housing are opposed to each other. By pressing the fastening holes 54 with bolts or the like, a pressing force is applied to the joined body 44.
[0037]
Assuming that the fuel cell of Comparative Example 1 without the spacer and the fuel cell of Example 1 with the spacer are formed in the same shape, the same material, and the same size, and the bolts are fastened with the same thrust. The structure of the fuel cell was numerically modeled by using the finite element method, and the contact structure analysis was performed to simulate the distribution of the stress applied to the joined body 44.
[0038]
FIG. 3 is a diagram showing a simulation result of a stress distribution of a joined body in Comparative Example 1 in which no spacer is provided. In the figure, the stress is 0.0-0.6kgf / mm 2 Is shown. In the figure, the area where the black color is dark has a stress of 0.1 gf / mm. 2 The following areas. As is clear from the figure, since the housing is fastened to the outer peripheral portion, the stress applied to the joined body 44 is concentrated near the outer periphery of the joined body 44, and the stress is near the center of the joined body 44. It is lower. The stress in FIG. 3 is 0.1 kgf / mm 2 The area of the above region was 36.0% of the total area of the joined body 44.
[0039]
FIG. 4 is a diagram illustrating a simulation result of the stress distribution of the joined body in the first embodiment in which the spacers are arranged. In the figure, the stress is 0.0-0.6kgf / mm 2 Is shown. In the figure, the area where the black color is dark has a stress of 0.1 gf / mm. 2 The following areas. As is clear from the figure, by arranging the spacer 53 adjacent to the joint body 44, even when the housing is fastened to the outer peripheral portion, the stress applied to the joint body 44 is not concentrated around the outer periphery and the joint is joined. A large stress is also applied near the center of the body 44. The stress in FIG. 4 is 0.1 kgf / mm 2 The area of the above region was 68.4% of the total area of the joined body 44.
[0040]
Next, the same flow rates of hydrogen gas and oxygen were supplied to the fuel cell of Comparative Example 1 in which the spacer shown in FIG. 2A was not provided and the fuel cell of Example 1 in which the spacer shown in FIG. 2B was provided. Then, the power generation reaction was actually performed, and the relationship between the output voltage and the output current was measured. FIG. 5 is a characteristic diagram showing an output current value and an output voltage value by power generation of the fuel cell in a graph. In the figure, the black square graph shows the output in Comparative Example 1 in which no spacer is arranged, and the black triangle graph shows the output in Example 1 in which the spacer is arranged. It is something.
[0041]
As is clear from FIG. 3, when the first embodiment and the first comparative example are compared at the same output voltage value, the first embodiment in which the spacers are arranged has a larger output current value and a larger power value. I understand. For example, when the output voltage value indicated by the thick line in the drawing is 600 mV, the output current value of Comparative Example 1 is 28.6 mA, and the output current value of Example 1 is 38.1 mA, as indicated by the broken line in the drawing. Met. Therefore, it can be seen that the power generation efficiency was improved by about 33% by arranging the spacers.
[0042]
The stress in the stress distribution by the simulation shown in FIGS. 3 and 4 is 0.1 kgf / mm. 2 Since the above area ratio was 36.0% in Comparative Example 1 and 68.4% in Example 1, the stress applied to the joined body 44 due to the arrangement of the spacers was 0.1 kgf / mm. 2 It can be seen that the above area increased by 32.4%. Since the increase in the area ratio of a certain value or more in the stress distribution is almost the same as the improvement in the power generation efficiency by the actual measurement, it can be seen that the improvement in the power generation efficiency is due to the uniform stress distribution.
[0043]
By uniformizing the distribution of stress applied to the joined body, it is possible to increase the catalyst utilization area by bringing the electrolyte and the catalyst layer into close contact, to reduce the contact resistance inside the joined body, and as a current collector as a diffusion layer. Thus, the porosity of the fuel becomes uniform, the fuel can be stably diffused, and the output can be improved.
[0044]
In addition, when the contact structure analysis is performed by the finite element method using a computer and the distribution of the stress applied to the joined body is simulated, the shape and material shape of the fuel cell components such as spacers and housings are changed In addition, it is possible to calculate the stress distribution. This makes it possible to predict the power generation efficiency of the fuel cell by calculating the stress distribution applied to the joined body by simulation before actually forming the fuel cell, and calculating the area ratio of the area where the stress exceeds a certain value. It becomes. Since the calculation can predict the improvement in the power generation efficiency of the fuel cell to some extent, it is possible to improve the development speed of the fuel cell.
[0045]
Next, an example in which a contact structure analysis is performed by a finite element method using a computer at the time of designing a fuel cell, a stress distribution applied to the joined body for each spacer shape is calculated, and an improvement in power generation efficiency is predicted. In the simulations described in the following embodiments, assuming that the casing and the fuel channel plate or the air channel plate are integrally formed, the calculation is performed by showing only the relationship between the casing, the spacer, and the joined body. It is assumed that the configuration of the fuel cell is the same as that shown in FIG.
[0046]
FIG. 6A is a cross-sectional view showing a configuration of the fuel cell in which the spacer is not provided in FIG. 6 as a comparative example 2, and FIG. 6B shows deformation of each member obtained by simulation. Comparative Example 2 is a fuel cell including a rectangular joined body 61 having a length of 30 mm × 70 mm in the vertical and horizontal sides, and a housing 62 arranged adjacent to the joined body 61. Also in Comparative Example 2, the case and the air flow path plate or the fuel flow path plate are integrally formed.
[0047]
As a simulation model, the deformation amount of each member was calculated by the contact structure analysis by the finite element method using the material property values when the electrolyte of the joined body 61 was polyethylene naphthalate and the housing 62 was aluminum. FIG. 6B illustrates a case where a concentrated load is applied to the fastening portions 63 formed on the sides in the longitudinal direction, and fastening is performed perpendicularly to the surface direction of the joined body 61. 62 shows a result obtained by calculating the deformation of the reference numeral 62. As is clear from FIG. 6B, the fastening is performed only at the fastening portions 63 formed on the sides in the longitudinal direction of the housing 62, so that the bonded body 61 and the central part of the housing 62 are bonded to each other. It can be seen that it is deformed into a convex shape opposite to the side on which it is arranged.
[0048]
FIG. 7 shows the result of calculating the stress distribution in the joined body 61 in Comparative Example 2. In the drawing, a region indicated by dark black is a region where stress is small, and a region indicated by light black is a region where stress is large. As is clear from the drawing, the stress applied to the joined body 61 is particularly large around the fastening portion 63 and is reduced as the distance from the fastening portion 63 increases.
[0049]
As described in the first embodiment, by increasing the region where the stress applied to the joined body 61 is equal to or more than a certain value, the real contact area between the catalyst layer and the electrolyte in the joined body 61 is increased, and Power generation efficiency can be improved. Therefore, even when the spacer is inserted between the housing 62 and the joint 61 of the comparative example 2 shown in FIG. 6 and the pressing force transmitted from the housing 62 to the joint 61 is dispersed by the spacer. By calculating a change in stress distribution by simulation using contact structure analysis by the finite element method, it is possible to predict an improvement in power generation efficiency of a fuel cell.
[0050]
FIG. 8 shows a second embodiment. FIG. 8A is a cross-sectional view showing a configuration of a fuel cell in which spacers are arranged, and FIG. 8B shows a simulation result of a stress distribution applied to the joined body. . The second embodiment is different from the first embodiment in that a rectangular joint body 71 having a vertical and horizontal length of 30 mm × 70 mm, a spacer 73 arranged adjacent to the joint body 71, and a housing 72 arranged adjacent to the spacer 73 It is a fuel cell composed of Also in the second embodiment, it is assumed that the housing and the air flow path plate or the fuel flow path plate are integrally formed.
[0051]
The spacer 73 is a rectangular plate-shaped member having substantially the same area as the joined body 71, and is bent so that the central portion is convex in the joined body 71 direction along the longitudinal direction. Therefore, the spacer 73 includes a pressure receiving portion 75 protruding in the direction of the housing 72, a pressing portion 76 having a central portion protruding in the direction of the joined body 71, and a transmitting portion 77 connecting the pressure receiving portion 75 and the pressing portion 76. Have. The pressure receiving portion 75 is a flat portion formed near the long side of the spacer 73 and is in contact with the housing 72. The pressing portion 76 is a flat portion formed at the central portion of the spacer 73 and is in contact with the joined body 71. The areas of the pressure receiving section 75 and the pressure section 76 are substantially the same. Since the pressurizing portion 76 comes into surface contact with the joined body 71, the spacer 73 is desirably formed of a porous material so as to transmit fuel gas and oxygen.
[0052]
Since the spacer 73 is disposed between the housing 72 and the joined body 71, even if a pressing force is applied to the fastening portion 74 formed near the long side of the housing 72, the pressure receiving portion 75 of the spacer 73 can be used. Receives the pressing force from the housing 72, and the pressing unit 76 transmits the pressing force to the joined body 71 via the transmission unit 77, so that the stress applied to the joined body 71 is dispersed from the fastening unit 74 and Also added to the central part.
[0053]
In order to confirm the effect of the spacer 73 with respect to the comparative example 2 in which no spacer is provided, the simulation model of the example 2 also assumes that the electrolyte of the joined body 71 is polyethylene naphthalate, as in the comparative example 2. The material property value when 72 is aluminum is used. Also, a concentrated load was applied to the fastening portion 74 formed on the longitudinal side of the housing 72, and fastening was performed perpendicularly to the surface direction of the joined body 71, and the calculation was performed by the contact structure analysis using the finite element method. .
[0054]
According to the result of calculating the distribution of stress applied to the joined body 71 in Example 2 shown in FIG. 8B, the region indicated by dark black in the drawing is a region where the stress is small, and indicated by light black. The region is a region where the stress is large. As is clear from FIG. 8B, by inserting the spacer 73 between the housing 72 and the joined body 71, the spacer 73 is added to the joined body 71 near the region where the transmission portion 77 is formed. It can be seen that the stress has increased.
[0055]
Therefore, by using a bent plate-shaped spacer 73 whose central portion is formed to be convex with respect to the bonded body 71, the pressure applied to the housing 72 is dispersed and the spacer 73 is bonded. The distribution of stress transmitted to the body 71 and applied to the joined body 71 can be made uniform. As described in the first embodiment described above, by uniformizing the distribution of stress applied to the joined body 71, the catalyst layer of the joined body 71 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0056]
FIG. 9 shows a third embodiment. FIG. 9A is a cross-sectional view showing the configuration of a fuel cell in which spacers are arranged, and FIG. 9B shows a simulation result of a distribution of stress applied to the joined body. . The third embodiment is different from the first embodiment in that a rectangular joint body 81 having vertical and horizontal sides of 30 mm × 70 mm, a spacer 83 arranged adjacent to the joint body 81, and a housing 82 arranged adjacent to the spacer 83 It is a fuel cell composed of Also in the third embodiment, it is assumed that the housing and the air channel plate or the fuel channel plate are integrally formed.
[0057]
The spacer 83 is a rectangular plate-like member having substantially the same area as the joined body 81. The spacer 83 is a pressure receiving part 85 formed on the housing 82 side of a long side portion, and a pressing part formed on the joined body 81 side. 86, and a transmission unit 87 that connects the pressure receiving unit 85 and the pressing unit 86. The pressure receiving portion 85 is a flat portion formed near the long side of the spacer 73 and is in contact with the housing 82. The pressing portion 86 is a planar portion formed on the entire surface of the spacer 83 on the joint body 81 side, and is in contact with the joint body 81. The long side portion of the spacer 83 forms a double structure of the pressure receiving portion 85 and the pressing portion 86 along the longitudinal direction, and a hollow region 88 is formed between the double structure by the transmission portion 77. .
[0058]
The area of the pressurizing section 86 is larger than the area of the pressure receiving section 85, and the entire surface of the pressurizing section 86 contacts the joint 81 to transmit the pressure. Can be Since the pressurizing portion 86 is in surface contact with the joined body 81, it is desirable that the spacer 83 be formed of a porous material so as to transmit fuel gas and oxygen.
[0059]
Since the spacer 83 is disposed between the housing 82 and the joint body 81, even if a pressing force is applied to the fastening portion 84 formed near the long side of the housing 82, the pressure receiving portion 85 of the spacer 83 Receives the pressing force from the housing 82 and the pressing unit 86 transmits the pressing force to the joined body 81 via the transmitting unit 87. Therefore, the stress applied to the joined body 81 is dispersed from the fastening unit 84 and It is applied uniformly over substantially the entire surface.
[0060]
In order to confirm the effect of the spacer 83 with respect to the comparative example 2 in which no spacer is provided, the simulation model of the example 3 also assumes that the electrolyte of the joined body 81 is polyethylene naphthalate, as in the comparative example 2, A material property value when 82 is aluminum is used. Also, a concentrated load was applied to the fastening portion 84 formed on the longitudinal side of the housing 82, and fastening was performed perpendicularly to the surface direction of the joined body 81, and the calculation was performed by the contact structure analysis by the finite element method. .
[0061]
According to the result of calculating the stress distribution applied to the joined body 81 in Example 3 illustrated in FIG. 9B, the region indicated by dark black in the diagram is a region where the stress is small, and indicated by light black. The region is a region where the stress is large. As is clear from FIG. 9B, the insertion of the spacer 83 between the housing 82 and the joined body 81 causes the joining of the spacer 83 to the joined body 81 near the region where the transmission portion 87 is formed. It can be seen that the stress has increased.
[0062]
Therefore, the spacer 83 has the pressure receiving portion 85, the pressing portion 86, and the transmitting portion 87, and the long side portion of the spacer 83 forms a double structure of the pressure receiving portion 85 and the pressing portion 86 along the longitudinal direction. By using the pressing part 86 that comes into contact with substantially the entire surface of the joined body 81, the pressure applied to the housing 82 is dispersed by the spacer 83 and transmitted to the joined body 81, and the distribution of the stress applied to the joined body 81 is reduced. Uniformity can be achieved. As described in the first embodiment described above, by uniformizing the stress distribution applied to the joined body 81, the catalyst layer of the joined body 81 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0063]
FIG. 10 shows a fourth embodiment. FIG. 10A is a cross-sectional view showing a configuration of a fuel cell in which spacers are arranged, and FIG. 10B shows a simulation result of a distribution of stress applied to a joined body. . In the fourth embodiment, a rectangular joint body 91 having a length of 30 mm × 70 mm in the vertical and horizontal sides, a spacer 93 arranged adjacent to the joint body 91, and a housing 92 arranged adjacent to the spacer 93 It is a fuel cell composed of In the fourth embodiment as well, it is assumed that the housing and the air channel plate or the fuel channel plate are formed integrally.
[0064]
The spacer 93 is a rectangular plate-shaped member having substantially the same area as the joined body 91, and includes a pressure receiving portion 95 formed on the housing 92 side, a pressing portion 96 formed on the joined body 91 side, It has a transmission part 97 that connects the pressure receiving part 95 and the pressure part 96. The pressure receiving portion 95 and the pressing portion 96 are planar portions having substantially the same area as the joined body 91, and form a double structure of the pressure receiving portion 95 and the pressing portion 96, and a transmission portion is provided between the double structures. A hollow region 98 is formed by 97.
[0065]
Since the pressure receiving portion 95 and the pressing portion 96 have the same area, the entire surface of the pressure receiving portion 95 is in contact with the housing 92, and the substantially entire surface of the pressure receiving portion 96 is in contact with the joined body 91 to transmit pressure. Pressure is uniformly applied to substantially the entire surface of the joined body 91. Since the pressurizing portion 96 comes into surface contact with the joined body 91, the spacer 93 is desirably formed of a porous material so as to allow fuel gas and oxygen to pass therethrough.
[0066]
Since the spacer 93 is disposed between the housing 92 and the joined body 91, even if a pressing force is applied to the fastening portion 94 formed near the long side of the housing 92, the pressure receiving portion 95 of the spacer 93 Receives the pressing force from the housing 92, and the pressing portion 96 transmits the pressing force to the joined body 91 via the transmitting portion 97, so that the stress applied to the joined body 91 is dispersed from the fastening portion 94 and the It is applied uniformly over substantially the entire surface.
[0067]
In order to confirm the effect of the spacer 93 with respect to the comparative example 2 in which the spacer is not provided, the simulation model of the example 4 also assumes that the electrolyte of the joined body 91 is polyethylene naphthalate as in the comparative example 2, A material property value when 92 is aluminum is used. In addition, a concentrated load was applied to the fastening portion 94 formed on the longitudinal side of the housing 92, and fastening was performed perpendicular to the surface direction of the joined body 91. .
[0068]
According to the result of calculating the distribution of stress applied to the joined body 91 in Example 4 shown in FIG. 10B, the region indicated by dark black in the drawing is a region where the stress is small, and is indicated by light black. The region is a region where the stress is large. As is clear from FIG. 10B, it can be seen that the stress applied to almost the entire surface of the joined body 91 is increased by inserting the spacer 93 between the housing 92 and the joined body 91.
[0069]
Therefore, the pressure receiving portion 95, the pressing portion 96, and the transmitting portion 97 are provided as the spacer 93, and the pressure receiving portion 95 and the pressing portion 96 form a double structure having substantially the same area as the joined body 91. By using the part 96 in contact with the substantially entire surface of the joined body 91, the pressure applied to the housing 92 is distributed to the spacer 93 and transmitted to the joined body 91, and the distribution of the stress applied to the joined body 91 is made uniform. Can be planned. As described in the first embodiment described above, by uniformizing the distribution of stress applied to the joined body 91, the catalyst layer of the joined body 91 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0070]
FIG. 11 is a cross-sectional view of a fuel cell in a case where the casing is bent to disperse the stress applied to the joined body according to the fifth embodiment. The simulation result is shown in FIG. Example 5 is a fuel cell including a rectangular joined body 101 having a length of 30 mm × 70 mm in the vertical and horizontal sides, and a casing 102 arranged adjacent to the joined body 101. Also in the fifth embodiment, it is assumed that the housing and the air channel plate or the fuel channel plate are integrally formed.
[0071]
The housing 102 is a plate-like member having substantially the same size as the joined body 101, and has a shape in which a central portion is convexly curved toward the joined body 101. Here, as the curved shape, the entire surface of the housing 102 may be curved with a uniform curvature, and the peripheral portion of the fastening portion 104 for fastening with a bolt or the like may be formed in a planar shape. In this embodiment, as shown in FIG. 6 (b), when a flat casing is fastened, the casing tends to swell at the central portion on the opposite side to the joined body. Are expanded in the direction of the joined body 101 to make the distribution of the stress applied to the joined body 101 uniform.
[0072]
When the housing 102 has a shape that is convexly curved with respect to the joint body 101 and a pressing force is applied to the fastening portion 104 formed near the long side of the housing 102, the housing 102 and the joint body 101 Starts to contact from the protruding portion of the housing 102. The pressing force applied to the fastening portion 104 is applied until the casing 102 is deformed and comes into contact with the joined body 101 over the entire surface. For this reason, the pressing force transmitted from the fastening portion 104 to the joined body 101 is dispersed at the central portion of the joined body 101 and is applied uniformly over substantially the entire surface of the joined body 101.
[0073]
In order to confirm the effect of the curvature of the housing 102 with respect to Comparative Example 2 in which the housing is a flat plate-like member, the simulation model of Example 5 is also similar to Comparative Example 2 except that the electrolyte of the bonded body 101 is changed. It is assumed that the material is polyethylene naphthalate, and a material property value when the housing 102 is aluminum is used. In addition, a concentrated load was applied to the fastening portion 104 formed on the side in the longitudinal direction of the housing 102, and fastening was performed perpendicular to the surface direction of the joined body 101. .
[0074]
According to the result of calculating the stress distribution applied to the joined body 101 in Example 5 shown in FIG. 11B, the region indicated by dark black in the drawing is a region where the stress is small, and indicated by light black. The region is a region where the stress is large. As is clear from FIG. 11B, it can be seen that the stress applied to the central portion of the joined body 101 is increased by forming the central portion of the housing 102 into a curved shape protruding in the direction of the joined body 101.
[0075]
Therefore, by making the central portion of the casing 102 a curved shape that is convex in the direction of the joined body 101, the pressing force applied to the fastening portion 104 is transmitted to the joined body 101 while the curved portion of the casing 102 is dispersed. The distribution of the stress applied to the joined body 101 can be made uniform. As described in the first embodiment described above, by making the distribution of stress applied to the joined body 101 uniform, the catalyst layer of the joined body 101 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0076]
FIG. 12 shows a configuration of a fuel cell in which the central portion of the housing is convexly curved in the direction of the joined body to disperse the stress applied to the joined body, as in the fifth embodiment as Example 6. FIG. 12A is a cross-sectional view, and FIG. 12B shows a simulation result of the distribution of stress applied to the joined body. The difference from the fifth embodiment is that the pressing force applied to the housing is applied in parallel to the surface of the joined body, and the structure used for the simulation of the fuel cell is the same as that of the fifth embodiment. Will be described using the same reference numerals.
[0077]
According to the calculation result of the stress distribution applied to the joined body 101 in Example 6 shown in FIG. 12B, the region indicated by dark black in the drawing is a region where the stress is small and indicated by light black. The region is a region where the stress is large. As is clear from FIG. 12B, the central portion of the casing 102 has a curved shape that is convex in the direction of the joined body 101, and the fastening portion 105 formed on the long side of the casing 102 has a curved surface. It can be seen that the stress applied to the central portion of the joined body 101 is increased by applying the pressing force in the parallel direction.
[0078]
Therefore, the pressing force applied to the fastening portion 105 is reduced by applying a pressing force in a direction parallel to the surface of the joined body 101 by forming a central portion of the casing 102 into a curved shape convex in the direction of the joined body 101. The curved portions are dispersed and transmitted to the joined body 101, and the distribution of the stress applied to the joined body 101 can be made uniform. As described in the first embodiment described above, by making the distribution of stress applied to the joined body 101 uniform, the catalyst layer of the joined body 101 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0079]
FIG. 13 shows a configuration of a fuel cell in which the central portion of the housing is convexly curved in the direction of the joined body to disperse the stress applied to the joined body, as in the fifth embodiment, as Example 7. FIG. 13A is a cross-sectional view, and FIG. 13B shows a simulation result of a stress distribution applied to the joined body. The difference from the fifth embodiment is that the pressing force applied to the housing is applied in a direction parallel and perpendicular to the surface of the joined body, and the structure used for the simulation of the fuel cell is different from that of the fifth embodiment. Since the same is applied, the description will be made using the same reference numerals.
[0080]
According to the calculation result of the stress distribution applied to the joined body 101 in Example 7 shown in FIG. 13B, the region indicated by dark black in the drawing is a region where the stress is small and indicated by light black. The region is a region where the stress is large. As is clear from FIG. 13B, the central portion of the casing 102 has a curved shape that is convex in the direction of the joined body 101, and is parallel to the surface of the joined body 101 at the fastening portion 105 formed on the long side of the casing 102. Direction, and by applying a pressing force in a direction perpendicular to the surface of the joined body 101 at the fastening portion 104 formed near the long side of the housing 102, the central part of the joined body 101 and the vicinity of the long side are joined. It can be seen that the applied stress is increasing.
[0081]
Therefore, the central portion of the housing 102 has a curved shape that is convex in the direction of the joined body 101, and the pressing force applied to the fastening portion 105 is applied to the surface of the joined body 101 in a direction parallel and perpendicular to the case. The curved portion of the body 102 is dispersed and transmitted to the joined body 101, and the distribution of the stress applied to the joined body 101 can be made uniform. As described in the first embodiment described above, by making the distribution of stress applied to the joined body 101 uniform, the catalyst layer of the joined body 101 and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, The contact resistance inside the joined body can be reduced, and the voids in the current collector as the diffusion layer become uniform, so that stable diffusion of the fuel can be maintained and the output can be improved.
[0082]
In the present embodiment, the pressing force applied to the housing is dispersed by processing the current collector constituting the joined body, and the true contact area between the catalyst layer of the joined body and the electrolyte is increased. FIG. 14 shows a configuration example of a fuel cell in which a collector is processed to form a joined body. Also in the present embodiment, it is described that the housing and the air channel plate or the fuel channel plate are integrally formed.
[0083]
FIG. 14A shows a structure in which current collectors 112 and 113 are formed on an electrolyte 111 to form a joined body, and a fastening portion 115 formed near a long side of a housing 114 extends in a direction perpendicular to the surface of the electrolyte 111. FIG. 4 is a cross-sectional view showing a state in which a pressing force is applied. The current collector 112 disposed in contact with the electrolyte 111 has substantially the same size as the electrolyte 111, and the electrolyte 111 and the current collector 112 are in contact with each other over substantially the entire surface. The current collector 113 is formed to be smaller than the current collector 112 and is disposed at a central portion adjacent to the current collector 112.
[0084]
Since the housing 114 is a flat member, when a pressing force is applied to the fastening portion 115, the central portion swells to the side opposite to the joined body as shown in FIG. 6B. In view of this, the current collector forming the joined body has a shape in which two members, large and small, are overlapped to increase the stress applied to the central portion between the electrolyte 111 and the current collector 112.
[0085]
FIG. 14B shows a structure in which the current collector 122 and the electrolyte 121 whose center is convexly curved in the direction of the electrolyte 121 form a joined body, and a fastening portion 125 formed near the long side of the housing 124 forms the electrolyte 121. FIG. 4 is a cross-sectional view showing a state in which a pressing force is applied to a surface in a vertical direction. The current collector 122 disposed adjacent to the electrolyte 121 has substantially the same size as the electrolyte 121, and has a shape in which a central portion is convexly curved toward the electrolyte 121.
[0086]
Since the housing 124 is a flat member, when a pressing force is applied to the fastening portion 125, the center portion swells to the side opposite to the joined body as shown in FIG. 6B. Therefore, the stress applied to the central portions of the electrolyte 121 and the current collector 122 is increased by making the central portion of the current collector 122 constituting the joined body convexly curved in the direction of the electrolyte 121. is there.
[0087]
Both the case where the large and small current collectors shown in FIG. 14A are superposed and the case where the center of the current collector shown in FIG. It is considered that the pressing force applied to the vicinity of the long side of the body is dispersed by the current collector, and increases the stress in the central portion between the electrolyte and the current collector. By uniformizing the distribution of stress applied to the joined body, the catalyst layer of the joined body and the electrolyte are brought into close contact with each other to increase the catalyst utilization area, to reduce the contact resistance inside the joined body, and as a diffusion layer. The porosity in the current collector becomes uniform, and stable diffusion of fuel can be maintained, and output can be improved.
[0088]
【The invention's effect】
By distributing the pressure applied to the fastening part by the spacer and transmitting it to the joined body, the pressure distribution applied to the joined body becomes uniform, and the electrolyte of the joined body and the current collector come into uniform contact with each other to collect the electrolyte. The real contact area at the interface of the conductor increases. By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved.
[0089]
The spacer has a pressure receiving portion that receives pressure applied from the housing, a pressure portion that applies pressure to the joined body, and a transmission portion that transmits a force between the pressure receiving portion and the pressure portion. By increasing the area of the surface where the pressurized portion contacts other members than the area of the surface that contacts other members, or by the pressurized portion contacting almost the entire surface of the joined body, the spacer can reduce the pressure. Dispersion can be achieved.
[0090]
The casing is a curved plate-like member. The central part is convex with respect to the joined body, so that the pressure applied to the joined body is dispersed by fastening the casing, and the pressure distribution applied to the joined body is uniform. In this case, the electrolyte of the joined body and the current collector contact uniformly, and the real contact area of the interface between the electrolyte and the current collector increases. By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved. At this time, even if the housing is fastened by applying a pressing force to the main surface of the plate member in the vertical direction at the fastening portion, or the housing is fastened by applying a pressing force to the main surface of the plate member in the horizontal direction. Then, the pressure applied to the joined body is dispersed.
[0091]
By dispersing the pressure applied from the fastening part by the current collector, the pressure distribution applied to the current collector and the electrolyte becomes uniform, and the electrolyte and the current collector contact uniformly, and the interface between the electrolyte and the current collector Increase the true contact area of the By increasing the area where the electrolyte and the current collector actually come into contact with each other, a power generation reaction easily occurs and the power generation efficiency of the fuel cell is improved. By stacking two plate-shaped members with different surface areas as a fuel electrode current collector or an oxygen electrode current collector, or by forming a curved plate shape with the central part of the surface protruding against the electrolyte , The current collector can disperse the pressure.
[0092]
By simulating the stress distribution by modeling the housing, the joined body, and the spacer, the stress distribution can be estimated before the fuel cell is actually created, which is suitable for making the stress distribution uniform. It is possible to know the spacer shape and the method of fastening the housing. In a fuel cell in which the distribution of stress applied to the joined body is uniform, the power generation efficiency can be improved, so that it is possible to easily design a fuel cell for improving the power generation efficiency.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of a fuel cell according to the present invention.
2 is an exploded view of the fuel cell used in the first embodiment of the present invention, FIG. 2 (a) shows a comparative example 1 in which no spacer is provided, and FIG. 2 (b) shows a grid-like spacer; Example 1 in which is disposed.
FIG. 3 is a diagram showing a distribution of stress applied to a joined body in Comparative Example 1 in which no spacer is arranged, calculated by simulation.
FIG. 4 is a diagram showing a distribution of stress applied to a joined body in Example 1 in which spacers calculated by simulation are arranged.
FIG. 5 is a graph showing an output current value and an output voltage value when power is generated using Comparative Example 1 and Example 1.
6A and 6B are diagrams illustrating a comparative example 2 in which no spacer is arranged when a fuel cell is simplified and modeled by a housing and a joined body, FIG. 6A is a cross-sectional view, and FIG. () Is a diagram showing a result of calculating deformation of the housing and the joined body by simulation.
FIG. 7 is a diagram showing, by simulation, a distribution of stress applied to a joined body in Comparative Example 2 in which no spacer is arranged.
8A and 8B are diagrams showing Example 2 in which a spacer is arranged between the housing and the joined body, FIG. 8A is a cross-sectional view, and FIG. 8B is a distribution of stress applied to the joined body by simulation; It is a figure which shows the result of having calculated.
9A and 9B are diagrams showing Example 3 in which a spacer is arranged between the housing and the joined body, FIG. 9A is a cross-sectional view, and FIG. 9B is a stress distribution applied to the joined body by simulation; It is a figure which shows the result of having calculated.
10A and 10B are diagrams showing Example 4 in which a spacer is arranged between the housing and the joined body, FIG. 10A is a cross-sectional view, and FIG. 10B is a distribution of stress applied to the joined body by simulation; It is a figure which shows the result of having calculated.
11A and 11B are diagrams showing Example 5 in which the casing is curved to achieve pressure distribution, FIG. 11A is a cross-sectional view, and FIG. 11B is a stress distribution applied to the joined body by simulation. It is a figure which shows the result of having calculated.
12A and 12B are diagrams showing Example 6 in which the housing is curved to distribute the pressure, FIG. 12A is a cross-sectional view, and FIG. 12B is a stress distribution applied to the joined body by simulation. It is a figure which shows the result of having calculated.
13A and 13B are diagrams showing Example 7 in which a casing is curved to achieve pressure distribution, FIG. 13A is a cross-sectional view, and FIG. 13B is a stress distribution applied to a joined body by simulation; It is a figure which shows the result of having calculated.
FIG. 14 shows an example 8 in which pressure distribution is achieved by processing a current collector of a joined body. FIG. 14 (a) shows an example in which large and small current collectors are superimposed. (B) shows an example in which the current collector is curved.
FIG. 15 is an exploded perspective view showing a configuration of a conventional fuel cell.
FIG. 16 is a schematic diagram showing a microscopic structure at an interface where a catalyst layer contacts an electrolyte.
[Explanation of symbols]
1,21,41,111,121 electrolyte
2,3,22,23,42,43,112,113,122 current collector
4,24,44,61,71,81,91,101 joined body
5, 6, 25, 26, 45, 62, 72, 82, 92, 102, 114, 124 cases
7,27,47 Fuel passage plate
8,28 Air flow plate
9,29 volts
10, 11, 30, 31 catalyst layer
12,35,55 Fuel flow path
13,36 Air flow path
14 Truth Contact Area
32, 33, 53, 73, 83, 93 spacer
34,54 fastening holes
37 opening
63, 74, 84, 94, 104, 105, 115, 125
75,85,95 Pressure receiving part
76, 86, 96 Pressurizing section
77, 87, 97 Transmission unit
88,98 hollow area

Claims (19)

燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、
前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体と、
前記筐体と前記接合体との間に配置されて前記締結部からの圧力を分散させて前記接合体に伝えるスペーサと、
を有することを特徴とする燃料電池。A joined body comprising an electrolyte sandwiched between a fuel electrode current collector and an oxygen electrode current collector,
A housing having a fastening portion arranged outside the joined body and applying pressure to the joined body,
A spacer that is disposed between the housing and the joined body and distributes pressure from the fastening unit to the joined body,
A fuel cell comprising: 前記スペーサによって前記接合体に伝えられる圧力が、前記接合体に略均一に加えられることを特徴とする請求項１記載の燃料電池。2. The fuel cell according to claim 1, wherein the pressure transmitted to the joined body by the spacer is applied to the joined body substantially uniformly. 前記燃料電極集電体および前記酸素電極集電体の前記電解質に接する面に、触媒層が形成されていることを特徴とする請求項１記載の燃料電池。2. The fuel cell according to claim 1, wherein a catalyst layer is formed on a surface of the fuel electrode current collector and the oxygen electrode current collector that is in contact with the electrolyte. 3. 前記スペーサは、前記筐体から加えられる圧力を受ける受圧部と、
前記接合体に圧力を加える加圧部と、
前記受圧部と前記加圧部との間で力を伝達する伝達部と
を有することを特徴とする請求項１記載の燃料電池。The spacer is a pressure receiving portion that receives pressure applied from the housing,
A pressurizing unit for applying pressure to the joined body,
The fuel cell according to claim 1, further comprising a transmission unit that transmits a force between the pressure receiving unit and the pressure unit. 前記受圧部が他の部材と接触する面の面積より、前記加圧部が他の部材と接触する面の面積が大きいことを特徴とする請求項４記載の燃料電池。5. The fuel cell according to claim 4, wherein an area of a surface of the pressure receiving portion in contact with another member is larger than an area of a surface of the pressure receiving portion in contact with another member. 前記加圧部が前記接合体の略全面に接触することを特徴とする請求項４記載の燃料電池。The fuel cell according to claim 4, wherein the pressurizing portion contacts substantially the entire surface of the joined body. 前記スペーサは、平板に開口部が複数形成された網目形状であることを特徴とする請求項１記載の燃料電池。The fuel cell according to claim 1, wherein the spacer has a mesh shape in which a plurality of openings are formed in a flat plate. 前記スペーサが屈曲した板状であり、前記スペーサの面の中央部分が前記接合体に対して凸に形成されていることを特徴とする請求項１記載の燃料電池。2. The fuel cell according to claim 1, wherein the spacer has a bent plate shape, and a central portion of a surface of the spacer is formed to be convex with respect to the assembly. 3. 前記スペーサが前記接合体に隣接して配置されることを特徴とする請求項１記載の燃料電池。The fuel cell according to claim 1, wherein the spacer is arranged adjacent to the assembly. 前記スペーサが多孔質材料により形成されてなることを特徴とする請求項９記載の燃料電池。The fuel cell according to claim 9, wherein the spacer is formed of a porous material. 前記スペーサと前記接合体とを接着するための接着層が、前記スペーサと前記接合体との間に設けられていることを特徴とする請求項９記載の燃料電池。10. The fuel cell according to claim 9, wherein an adhesive layer for adhering the spacer and the joined body is provided between the spacer and the joined body. 燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、
前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体とを有し、
前記燃料電極集電体または前記酸素電極集電体が前記締結部からの圧力を分散して、前記燃料電極集電体または前記酸素電極集電体と前記電解質とが接触する圧力を均一にすることを特徴とする燃料電池。A joined body comprising an electrolyte sandwiched between a fuel electrode current collector and an oxygen electrode current collector,
A housing having a fastening portion disposed outside the joined body and applying pressure to the joined body,
The fuel electrode current collector or the oxygen electrode current collector disperses the pressure from the fastening portion to make the pressure at which the fuel electrode current collector or the oxygen electrode current collector contacts the electrolyte uniform. A fuel cell, characterized in that: 前記燃料電極集電体または前記酸素電極集電体として、表面積の異なる二枚の板状部材を重ね合わせることを特徴とする請求項１２記載の燃料電池。13. The fuel cell according to claim 12, wherein two plate members having different surface areas are overlapped as the fuel electrode current collector or the oxygen electrode current collector. 前記燃料電極集電体または前記酸素電極集電体が湾曲した板状であり、前記燃料電極集電体または前記酸素電極集電体の面の中央部分が前記電解質に対して凸に形成されることを特徴とする請求項１２記載の燃料電池。The fuel electrode current collector or the oxygen electrode current collector has a curved plate shape, and a central portion of a surface of the fuel electrode current collector or the oxygen electrode current collector is formed to be convex with respect to the electrolyte. The fuel cell according to claim 12, wherein: 燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、
前記接合体の外部に配され前記接合体に圧力を加える締結部を有する筐体とを有し、
前記筐体は、中央部分が前記接合体に対して凸に形成されて湾曲した一対の板状部材を締結することにより構成される
ことを特徴とする燃料電池。A joined body comprising an electrolyte sandwiched between a fuel electrode current collector and an oxygen electrode current collector,
A housing having a fastening portion disposed outside the joined body and applying pressure to the joined body,
The fuel cell is characterized in that the casing is formed by fastening a pair of curved plate-shaped members whose central portion is formed to be convex with respect to the joined body. 前記締結部において、前記板状部材の主面に垂直方向に押圧力を加えて前記一対の板状部材を締結することを特徴とする請求項１５記載の燃料電池。16. The fuel cell according to claim 15, wherein the fastening portion fastens the pair of plate members by applying a pressing force in a direction perpendicular to a main surface of the plate member. 前記締結部において、前記板状部材の主面に水平方向に押圧力を加えて前記一対の板状部材を締結することを特徴とする請求項１５記載の燃料電池。The fuel cell according to claim 15, wherein the pair of plate members is fastened by applying a pressing force to the main surface of the plate member in a horizontal direction at the fastening portion. 燃料電極集電体と酸素電極集電体とで電解質を挟持してなる接合体と、前記接合体の外部に配される筐体と、前記筐体と前記電解質との間に配置されるスペーサとをモデル化する手順と、
前記筐体に圧力を加えた際に前記接合体に加わる応力分布をシミュレーションする手順と、
前記応力分布において応力が閾値以上である面積の割合を求める手順と
を有することを特徴とする燃料電池の設計方法。A joined body in which an electrolyte is sandwiched between a fuel electrode current collector and an oxygen electrode current collector, a housing arranged outside the joined body, and a spacer arranged between the housing and the electrolyte And the steps to model
Procedure for simulating the stress distribution applied to the joined body when applying pressure to the housing,
Obtaining a ratio of an area in which the stress is equal to or larger than a threshold value in the stress distribution. 前記応力分布のシミュレーションに、有限要素法による接触構造解析を用いることを特徴とする請求項１８記載の燃料電池の設計方法。19. The fuel cell design method according to claim 18, wherein the simulation of the stress distribution uses a contact structure analysis by a finite element method.
JP2003116639A 2003-04-22 2003-04-22 Fuel cell Expired - Fee Related JP4661026B2 (en)

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JP2008091329A (en) * 2006-09-07 2008-04-17 Sumitomo Chemical Co Ltd Method for evaluating durability of unit cell, device for evaluating durability, program for evaluating durability, and unit cell of fuel cell
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JP2002298891A (en) * 2001-03-30 2002-10-11 Osaka Gas Co Ltd Deterioration promoting device and deterioration promoting method

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006216247A (en) * 2005-02-01 2006-08-17 Honda Motor Co Ltd Fuel cell stack
JP2008091329A (en) * 2006-09-07 2008-04-17 Sumitomo Chemical Co Ltd Method for evaluating durability of unit cell, device for evaluating durability, program for evaluating durability, and unit cell of fuel cell
JP2012022961A (en) * 2010-07-16 2012-02-02 Toyota Motor Corp Creation method of bonding model
JP2016225078A (en) * 2015-05-28 2016-12-28 日本特殊陶業株式会社 Fuel cell structure
FR3080223A1 (en) * 2018-04-17 2019-10-18 Commissariat A L'energie Atomique Et Aux Energies Alternatives METHOD FOR DETERMINING A SIZING OF AN ELECTROCHEMICAL CELL WITH PRINTED CIRCUIT TYPE HOLDING PLATES
EP3557670A1 (en) * 2018-04-17 2019-10-23 Commissariat à l'Énergie Atomique et aux Énergies Alternatives Method for determining sizing of an electrochemical cell with printed circuit board type holding plates
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