200836394 九、發明說明 【發明所屬之技術領域】 本發明係有關燃料電池，特別是小型之液體燃料直接 供給型之燃料電池。 【先前技術】 ‘ 近年，經由電子技術的進步，電子機器的小型化，高 φ 性能化，便攜化則持續進展，而針對在攜帶用電子機器， 係強力要求所使用之電池的高能量密度化，因此，輕量且 小型的同時，要求高容量的二次電池。 對於對如此之二次電池的要求而言，例如，開發有鋰 離子二次電池’另外，攜帶電子機器的動作時間係有更加 增加的傾向，並在鋰離子二次電池之中，從材料的觀點， 以及構造的觀點，能量密度之提升係幾乎到達極限，而成 爲無法對應更加的要求。 Φ 依據如此之狀況，取代鋰離子二次電池，小型之燃料 電池則被受注目，特別是作爲燃料而使用甲醇之直接甲醇 型燃料電池（DMFC: Direct Methanol Fuel Cell)係比較於 ， 使用氫氣之燃料電池，氫氣之處裡的困難度，或無需將有 機燃料進行改質而製作氫之裝置等，對於小型化優越。 在D MFC之中，係在燃料極而氧化分解甲醇，生成二 氧化碳，質子及電子，另一方面，在空氣極之中，經由從 空氣所得到之氧，和經過電解質膜而從燃料及所供給之質 子’以及從燃料極通過外部電路所供給之電子而生成水， -5- 200836394 另外，經由通過其外部電路之電子，供給電 針對在DMFC係爲了由如此的構成進行 補助器具備有供給甲醇之閥或送入空氣之風 爲系統構成複雜型態之DMFC，因此，在其: 中係不易謀求小型化。 因此，並非由閥而供給甲醇，而於甲醇 元件之間，設置通過甲醇的分子的膜，取代 由將甲醇收容室接近至發電原件附近之情況 展，另外，例如對於 W02005/1 12 1 72公報 於空氣的導入，未使用風箱而由設置直接安 之吸氣口的情況，構築小型DMFC，但，如J 取代簡略化機構，而受到溫度等之外部環境 況，對於發電元件傳送一定量之甲醇的情況 因此，安定輸出而高現出之情況則變爲困難 另外，對於日本特開2004- 1 7 1 844號公 爲了控制如此之甲醇之供給量，而於燃料收 之間，設置多孔體，集中甲醇供給量之技術 但，在上述以往之燃料電池的構成中， 構，而經由反應而生成的水混入於燃料，燃 ，對於發電元件供給一定濃度的燃料之情況 此，現出高輸出之情況則爲困難。 [專利文獻1] WO 200 5/1 1 2 1 72公報 [專利文獻2]日本特開2004- 1 7 1 844號公 α ° 發電，而作爲 箱，並開發作 構造之DMFC 收容室與發電 透過甲醇，而 ，朝小型化發 ’係揭不有對 裝於發電元件 t[:之 DMFC 係 要因之影響情 則變爲困難， 〇 報，係揭示有 容部分與負極 〇 取代簡略化機 料濃度則下降 則爲不易，因 報 -6- 200836394 【發明內容】 θ it ’本發明的目的係提供可控制燃料濃度之下降同 時’可供給燃料於燃料極者，並可在長期之連續使用，維 持安定之輸出的燃料電池者。 如根據本發明之一形態，屬於具備：具有燃料極觸媒 層及面向於前述燃料極觸媒層之一方的面所設置之燃料極 氣體擴散層的燃料極，具有空氣極觸媒層及面向於前述空 氣極觸媒層之一方的面所設置之空氣極氣體擴散層的空氣 極’以及由夾持於前述燃料極觸媒層與前述空氣極觸媒層 之電解質膜所構成之膜電極接合體之燃料電池，其中，提 供前述燃料極氣體擴散層之氣孔率乃較前述空氣極氣體擴 散層之氣孔率爲小之燃料電池。 另外，如根據本發明之一形態，屬於具備：具有燃料 極觸媒層及面向於前述燃料極觸媒層之一方的面所設置之 燃料極氣體擴散層的燃料極，具有空氣極觸媒層及面向於 前述空氣極觸媒層之一方的面所設置之空氣極氣體擴散層 的空氣極，以及由夾持於前述燃料極觸媒層與前述空氣極 觸媒層之電解質膜所構成之膜電極接合體之燃料電池，其 中，提供將前述燃料極觸媒層之氣孔率乃較前述空氣極觸 媒層之氣孔率爲小之燃料電池。 更加地，如根據本發明之一形態，屬於具備：具有燃 料極觸媒層及面向於前述燃料極觸媒層之一方的面所設置 之燃料極氣體擴散層的燃料極，具有空氣極觸媒層及面向 於前述空氣極觸媒層之一方的面所設置之空氣極氣體擴散 200836394 層的空氣極，以及由夾持於前述燃料極觸媒層與前述空氣 極觸媒層之電解質膜所構成之膜電極接合體之燃料電池， 其中，提供將前述燃料極氣體擴散層之氣孔率乃較前述空 氣極氣體擴散層之氣控率爲小，且前述燃料極觸媒層之氣 孔率乃較前述空氣極觸媒層之氣孔率爲小之燃料電池。 另外，本發明之燃料電池係亦可具備收容液體燃料， 具有爲了導出前述液體燃料之氣化成分的開口之液體燃料 收容室，和呈封塞前述液體燃料收容室之開口地所配設， 使前述液體燃料之氣化成分朝向前述燃料極之燃料極氣體 擴散層而透過之氣液分離膜。 另外，本發明之燃料電池係亦可具備配置於前述膜電 @ ί妾合體之燃料極側，分配燃料供給於前述燃料極之燃料 極氣體擴散層的燃料分配機構，和收容液體燃料，藉由前 述燃料分配機構與流路所連接之燃料收容部。 【實施方式】 [爲了實施發明之最佳型態] 以下，關於本發明之一實施形態，參照圖面而進行說 明。 圖1係爲模式性地表示有關本發明之一實施型態之直 接甲醇形的燃料電池1 〇的圖。 如圖1所示，燃料電池1〇係做爲起電部而具備由燃 料極觸媒層1 1及燃料極氣體擴散層1 2而成之燃料極，與 由空氣極觸媒層13及空氣極氣體擴散層14而成之空氣極 -8- 200836394 ，與夾持於燃料極觸媒層11與空氣極觸媒層1 3之間的質 子（氫離子）傳導性的電解質膜15所構成之膜電極複合 體（MEA : Membrane Electrode Assembly ) 16 〇 作爲含於燃料極觸媒層1 1及空氣極觸媒層1 3之觸媒 係可舉出例如爲白金族元素Pt，Pu，Rh，Ir，Os，Pd等 之單體金屬，含有白金族元素之合金等，具體而言，作爲 燃料極觸媒層1 1，理想則採用對於甲醇或一氧化碳而言， 具有強耐性之Pt-Ru或Pt-Mo等情況，而作爲空氣極觸媒 層13，理想則採用白金或Pt-Ni等情況，但，並不侷限於 此等構成，另外，亦可爲使用如碳素材料之導電性載持體 的載持觸媒，或使用無機載持體觸媒。 另外，燃料極觸媒層1 1及空氣極觸媒層1 3係具有特 定之氣孔率所構成，並燃料極觸媒層1 1之氣孔率係做爲 較空氣極觸媒層13之氣孔率爲小所設定，具體而言，燃 料極觸媒層1 1之氣孔率係爲空氣極觸媒層1 3之氣孔率的 20〜80%，理想爲40〜70%，更理想爲50〜70%，在此，將對 於空氣極觸媒層1 3之氣孔率的燃料極觸媒層1 1之氣孔率 的比例，作爲其範圍之情況，對於其比例較20%爲小之情 況，係因對於燃料極觸媒層1 1本身之甲醇燃料浸透性下 降，而未促進改質反應，另外，對於其比例較80%爲大之 情況，係因氣化之甲醇燃料則透過燃料極觸媒層1 1，並亦 透過電解質膜15而至空氣極觸媒層13爲止進行交迭，而 引起不必要之反應而降低輸出電位，另外，在另一方，因 透過電解質膜1 5的水則通過燃料極氣體擴散層1 2，之後 -9 - 200836394 氣化而混入於液體燃料收容室2 1。 作爲構成電解質膜1 5之質子傳導性材料係可舉出例 如，如具有磺酸基， 例如，全氟黃酸聚合體之氟素樹脂（Nafion (商品名 、DuPont公司製），Flemion (商品名、旭硝子公司製） 等），具有磺酸基之碳化氫樹脂，鎢酸或磷鎢酸等之無機 物等，但，並不限定於此等之構成。 層積於陽極觸媒層24之陽極氣體擴散層25係完成均 一地供給燃料於陽極觸媒層24的作用同時，亦兼具陽極 觸媒層24之集電體，而層積於陰極觸媒層26之陰極氣體 擴散層27係完成均一地供給氧化劑於陰極觸媒層26的作 用同時，亦兼具陰極觸媒層26之集電體。 另外，燃料極氣體擴散層1 2及空氣極氣體擴散層1 4 係因爲了使氣體通過，故由多孔質體而成之公知的導電性 材料所構成，而燃料極氣體擴散層1 2及空氣極氣體擴散 層14係例如由碳纖維紙，碳纖維織布所構成，但並不侷 限於此等之構成，例如，燃料極氣體擴散層1 2或空氣極 氣體擴散層1 4係理想爲由可調整氣孔率情況之材料所構 成，例如，理想爲使用以壓縮的情況而可使體積，即，密 度變化之碳纖維紙等，燃料極氣體擴散層1 2之氣孔率係 做爲較空氣極氣體擴散層1 4之氣孔率爲小所設定，具體 而言，燃料極氣體擴散層1 2之氣孔率係爲空氣極氣體擴 散層14之氣孔率的20〜80%，理想爲40〜7〇°/❶，更理想爲 5 0〜7 0%，在此，將對於空氣極氣體擴散層14之氣孔率的 -10- 200836394 燃料極氣體擴散層1 2之氣孔率的比例，作爲其範圍之情 況，對於其比例較20%爲小之情況，係因藉由燃料極氣體 擴散層1 2而供給適量之氣化燃料於燃料極觸媒層1 1之情 況變爲困難，另外，對於其比例較80%爲大之情況，係因 氣化之甲醇燃料則過剩地供給至燃料極觸媒層Π，過剩之 甲醇燃料則透過燃料極觸媒層1 1，並亦透過電解質膜1 5 而至空氣極觸媒層13爲止進行交迭，而引起不必要之反 應而降低輸出電位，另外，在另一方，因透過電解質膜15 的水則通過燃料極氣體擴散層1 2，之後氣化而混入於液體 燃料收容室21。 然而，針對在將燃料極觸媒層1 1之氣孔率，做爲較 空氣極觸媒層13之氣孔率爲小所設定之情況，亦可將燃 料極氣體擴散層1 2之氣孔率係做爲較空氣極氣體擴散層 1 4之氣孔率爲小所設定。 另外，對於燃料極氣體擴散層1 2，係層積燃料極導電 層1 7，對於空氣極氣體擴散層1 4，係層積空氣極導電層 18，而燃料極導電層17及空氣極導電層18係理想爲例如 ’使用白金，金等貴金屬，鎳或不銹鋼等耐飩性金屬等之 金屬材料而成之多孔質層（例如，金屬篩孔）或箔體者，另 外亦可各自使用將金或碳纖維之導電性材，以異種金屬進 行表面處理之材料，被覆金等之良導電性金屬於銅或不銹 鋼的複合材料者，燃而，燃料極導電層17及空氣極導電 層1 8係呈不會從此等周緣，燃料或氧化劑產生洩漏地加 以構成。 -11 - 200836394 另外，燃料極導電層17與電解質膜15之間’係配置 具有矩形框狀之燃料極密封材1 9之同時’圍住燃料極觸 媒層11及燃料極氣體擴散層12的周圍’另一方面’空氣 極導電層18與電解質膜15之間，係配置具有矩形框狀之 空氣極密封材20之同時，圍住空氣極觸媒層13及空氣極 氣體擴散層1 4之周圍，而燃料極密封材1 9及空氣極密封 材20係例如由橡膠製之0環等所構成，並防止從膜電極 接合體1 6之燃料洩漏及氧化劑洩漏，然而’燃料極密封 材19及空氣極密封材20之形狀並不侷限於矩形形狀’而 成對應於燃料電池1 〇之外緣形地適宜所構成。 另外，如圖1所示，呈被複收容液體燃料F之液體燃 料收容室2 1之開口部地，配置氣液分離膜22，對於氣液 分離膜22上，係配置由對應於燃料電池1 〇之外緣的形狀 所構成之框體23(在此係矩形的框體），並且，對於其框體 23上，係燃料極導電層17乃呈框體23上地層積配置有具 備上述之燃料極導電層17及空氣極導電層18之膜電極接 合體16，在此，框體23係由電性絕緣材料所構成，而具 體而言，例如由如聚對苯二甲二乙酯（PET)之熱可塑性聚 酯樹脂等所形成。 另外，儲存於液體燃料容器21之液體燃料F係爲濃 度超過50%摩爾之甲醇水溶液，或純甲醇，另外，純甲醇 之純度係理想爲作爲95重量％以上100重量％以下者，另 外，液體燃料F之氣化成分係指，對於作爲液體燃料F使 用液體之甲醇的情況，係意味氣化之甲醇，對於作爲液體 -12- 200836394 燃料F使用甲醇水溶液的情況，係意味甲醇之氣化成分與 由水之氣化成分而成之混和氣。 另外，爲以氣液分離膜22、燃料極導電層17及框體 23所圍住之空間的氣化燃料收容室24係暫時性地收容透 過氣液分離膜22之液體燃料F的氣化成分，更加地，作 ^ 爲將針對在氣化成分之燃料的濃度分佈作爲均一之空間而 * 發揮機能。 φ 另外，上述之氣液分離膜22係爲分離液體燃料F之 氣化成分與液體燃料F，並使其氣化成份透過於燃料極觸 媒層1 1側之構成，而其氣液分離膜22係對於液體燃料F 而言，由爲不活性不溶解之材料，構成爲薄板狀，具體而 言，由矽橡膠，低密度聚乙烯（LDPE)薄膜，聚氯乙烯 (PVC)薄膜，聚對苯二甲酸乙二醇酯（PET)薄膜，氟素樹脂 (例如，聚四氟乙烯（PTFE)，四氟乙烯•全氟烷基乙烯醚 共聚物（PFA)等）微多孔膜等之材料所構成。 Φ 另一方面，對於空氣極導電層1 8上，係藉由以對應 於燃料電池1 0之外緣形的形狀所構成之框體25 (在此係爲 * 矩形的框體），層積保濕層26，另外，對於保濕層26上’ ^ 係做爲表面層而發揮機能，層積形成有複數個爲了導入爲 氧化劑之空氣的空氣導入口 28之表面罩體層27，而其表 面罩體層27係因由加壓含有膜電極接合體16之層積體， 亦達成提升其密著性之作用，故例如由如SU S3 04之金屬 所形成，另外，框體25係與框體23同樣地，由電性絕緣 材料所構成，具體而言，例如由如聚對苯二甲酸乙二醇酯 -13- 200836394 (PET)之熱可塑性聚酯樹脂等所形成。 另外，保濕層2 6係浸含針對在空氣極觸媒層1 3所生 成的水之一部分，構成控制水的蒸發之作用之同時’經由 均一地導入氧化劑於空氣極氣體擴散層1 4之情況’亦具 有作爲促進對於空氣極觸媒層1 3之氧化劑之均一擴散的 補助擴散層之機能，而其保濕層2 6係例如由聚乙烯多孔 質膜等之材料所構成，並使用其最大的孔徑則爲20〜5 0 w 程度的膜，而將最大的孔徑做爲其範圍之情況，係對於孔 徑較20 W爲小的情況，係因空氣透過量下降，而對於較 50擇爲大之情況，係因水分蒸發成爲過多，然而，從經由 浸透壓現象之空氣極觸媒層1 3側對於燃料極觸媒層1 1之 水的移動係可由改變針對在設置於保濕層26上之表面罩 體層27的空氣導入口 28個數或尺寸，調整開口部面積等 之情況而控制者。 然而，燃料電池1 0之構成係並非侷限於上述之構成 者，而例如，亦可於燃料極導電層1 7與框體23之間，設 置疏水性之多孔膜，而由設置其多孔膜之情況，可防止從 藉由多孔膜之燃料極氣體擴散層1 2側對於氣化燃料收容 室24側之水的侵入，而做爲具體之多孔膜的材料，例如 ，可舉出聚四氟乙烯（PTEF)，做爲潑水化處理之矽薄板等 〇 另外，其氣液分離膜2 2之更加地於液體燃料收容室 21側，具有與氣液分離膜2 2同樣之氣液分離機能，更加 地亦可設置調整燃料之氣化成分的透過量之透過量調整膜 -14- 200836394 ’而經由其透過量調整膜之氣化成分的透過量之調整係由 調整設置於透過量調整膜之開孔部的口徑而進行，而其透 過量調整膜係可由聚對苯二甲酸乙二醇酯等之材料而構成 ’由設置其透過量調整膜之情況，可調整供給於燃料極觸 媒層11側之燃料的氣化成分之供給量者。 接著，關於針對在上述之燃料電池1 0 0的作用，進行 - 說明。 φ 燃料收容部2 1內之液體燃料F(例如，甲醇水溶液）產 生氣化’並其氣化之甲醇與水蒸氣之混和氣則透過氣液分 離膜22，暫時收容於氣化燃料收容室24，均一地進行濃 度分佈，而暫時收容於氣化燃料收容室24之混和氣係通 過燃料極導電層1 7，更加地由燃料極氣體擴散層1 2所擴 散，供給至燃料極觸媒層1 1，而供給至燃料極觸媒層11 之混合氣係產生下記（1)式所示之甲醇的內部改質反應。 • CH30H + H20— C02 + 6H + + 6e-···式（1) " 然而，對於作爲液體燃料F使用純甲醇之情況，係因 - 未從液體燃料容器21供給水蒸氣，故在空氣極觸媒層1 3 生成的水或電解質膜15中的水等，與甲醇產生上述（1)式 的內部改質反應，或者，未經由上述（1)式的內部改質反應 ，而根據無需水之其他反應機構，產生內部改質反應。 由內部改質反應所生成之質子（H + )係傳導在電解質膜 15，並到達至空氣極觸媒層13，而從表面罩體層27的空 -15- 200836394 氣導入口 28所攝取之空氣係擴散在保濕層26，空氣極導 電層18，空氣極氣體擴散層14，供給至空氣極觸媒層u ’另’供給至空氣極觸媒層13之空氣係產生接下來之（2) 式所示之反應，根據此反應，生成水而產生發電反應 (3/2) 02 + 6H + + 6e-— 3 Η20·"式（2) 經由其反應而生成於空氣極觸媒層1 3中的水係擴散 在空氣極氣體擴散層1 4而到達至保濕層26，並一部分的 水係從設置於保濕層26上之表面罩體層27的空氣導入口 28所蒸散，而剩餘的水係暫時儲存於保濕層26，通過空 氣極氣體擴散層1 4而到達至空氣極觸媒層1 3，更加地， 當在進行式（2)的反應時，生成水量則增加，並空氣極觸媒 層1 3中的水分儲藏量則增加，對於此情況，伴隨著式（2) 的反應之進行，空氣極觸媒層1 3中之水分儲藏量則成爲 較燃料極觸媒層1 1之水分儲藏量爲多之狀態，其結果， 經由浸透現象，生成於空氣極觸媒層1 3的水則促進通過 電解質膜1 5而移動至燃料極觸媒層1 1之現象，因此，將 對於燃料極觸媒層1 1之水分的供給，比較於只仰賴從液 體燃料容器2 1氣化之水蒸氣的情況，促進了水的供給， 而可使在前述式（1)之甲醇的內部改質反應促進。 另外，一般，從空氣極側透過於燃料極側的水之一部 分係通過燃料極氣體擴散層12，成爲水蒸氣’透過氣液分 離膜22而流入至液體燃料收容室2 1內，而當流入至液體 -16- 200836394 燃料收容室21內之水的量爲多時，將引起液體燃料收容 室2 1內之甲醇濃度的下降等，作爲其結果，對於燃料極 觸媒層1 1之甲醇供給量則不足而產生輸出劣化，但，在 本發明中，由將燃料極氣體擴散層1 2之氣孔率，作爲較 空氣極氣體擴散層1 4之氣孔率爲低而設定之情況，因透 過電解質膜15的水則不亦通過燃料極氣體擴散層12,故 控制了由燃料極氣體擴散層1 2在液體燃料收容室2 1側產 生之燃料濃度之下降，另外，對於燃料極內，係因可儲存 爲了使式（2)之反應進行的水，故可維持與透過燃料極氣體 擴散層1 2之氣化的甲醇之化學反應者，因此，可保持長 時間維持安定之輸出密度者。 另一方面，針對在空氣極，係有必要多從空氣中攝入 對於在空氣極觸媒層1 3，而在本發明中，經由將燃料極氣 體擴散層12之氣孔率，作爲較空氣極氣體擴散層14之氣 孔率爲低而設定之情況，對於在前述之式（2)的反應，供給 充分的量之氧氣，經由此，亦可保持長時間維持安定之輸 出密度者。 另外，作爲液體燃料F，即使在使用甲醇濃度超過5 0 摩爾％之甲醇水溶液，或純甲醇的情況，因可使用從空氣 極觸媒層1 3移動至燃料極觸媒層1 1的水於內部改質反應 之情況，故可安定進行對於燃料極觸媒層1 1之水的供給 ，由此，更可降低甲醇的內部改質反應之反應阻抗，進而 更可提升長期輸出性與負荷電流特性者，更加地，亦可謀 求液體燃料收容室2 1之小型化情況。 -17- 200836394 然而，在此，關於就將燃料極氣體擴散層1 2之氣孔 率係做爲較空氣極氣體擴散層1 4之氣孔率爲小所設定之 情況，已做過說明，但關於就將燃料極觸媒層11之氣孔 率係做爲較空氣極觸媒層1 3之氣孔率爲小所設定之情況 ，亦得到同樣的效果，更加地，關於就將燃料極氣體擴散 層12之氣孔率係做爲較空氣極氣體擴散層14之氣孔率爲 小所設定，且將燃料極觸媒層11之氣孔率係做爲較空氣 極觸媒層1 3之氣孔率爲小所設定之情況，亦得到同樣的 效果。 如根據上述，一實施形態之直接甲醇型之燃料電池10 ，由將燃料極氣體擴散層1 2之氣孔率係做爲較空氣極氣 體擴散層14之氣孔率爲小所設定之情況，及/或將燃料極 觸媒層11之氣孔率係做爲較空氣極觸媒層13之氣孔率爲 小所設定之情況，可將在空氣極所生成的水儲存於燃料極 內者，由此，可控制由燃料極氣體擴散層1 2，其水侵入至 液體燃料收容室21側之情況，並由此，因可控制由燃料 極氣體擴散層1 2，在液體燃料收容室2 1側產生之燃料濃 度下降之情況，並可供給特定濃度之燃料於燃料極觸媒層 1 1，故可抑制經由連續運轉之燃料電池的輸出下降者。 另外，由將燃料極氣體擴散層1 2之氣孔率係做爲較 空氣極氣體擴散層1 4之氣孔率爲小所設定之情況，及/或 將燃料極觸媒層1 1之氣孔率係做爲較空氣極觸媒層1 3之 氣孔率爲小所設定之情況，可供給對於在空氣極觸媒層1 3 產生之反應充分量之氧氣，經由此，亦可抑制經由連續運 -18- 200836394 轉之燃料電池的輸出下降者。 然而，在上述之實施形態之中，關於對於液 使用甲醇溶液或純甲醇之直接甲醇型的燃料電池 說明，但液體燃料，並不侷限於此，而亦可爲例 溶液或純乙醇等之乙醇燃料，丙醇水溶液或純丙 醇燃料，乙二醇水溶液或純乙二醇等之乙二醇燃 醚’蟻酸，或其他的液體燃料，無論如何均收容 電池之液體燃料，另外，燃料電池係對於主動型 池’更加地對於燃料供給等一部分使用閥等之半 燃料電池而言，亦可適用本發明，並得到與使用 燃料電池的情況同樣之作用效果。 接著，關於具備上述之膜電極接合體16，有 之一實施型態之直接甲醇型的燃料電池其他構成 2及圖3而進行說明。 Η 2係係模式性地表示有關本發明之一實施 他構成之直接甲醇型的燃料電池〗〇 〇剖面的圖， 模式性地表示燃料分配機構i 3 〇之構成斜視圖， 於與上述之一實施型態的燃料電池1 〇之構成同 ’係附上同一之符號而省略或簡略重複之說明。 如圖2所示，膜電極接合體1 6係由燃料極丨 及燃料極氣體擴散層i 2而成之燃料極，與空氣 13及空氣極氣體擴散層14而成之空氣極，，與 料極觸媒層11與空氣極觸媒層13之間的質子（ 傳導性的電解質膜i 5所構成。 體燃料， ，進行過 如乙醇水 醇等之丙 料，二甲 因應燃料 之燃料電 被動型之 被動型之 關本發明 ，參照圖 型態之其 圖3係爲 然而，對 一的部分 獨媒層1 1 極觸媒層 夾持於燃 氫離子） -19- 200836394 對於電解質膜1 5與後述之燃料分配機構i 3 〇之間， 係介入存在有燃料極密封材1 9，對於電解質膜1 5與表面 罩體層27之間，係介入存在有空氣極密封層2〇，經由此 等而防止從膜電極接合體1 6的燃料洩漏或氧化劑洩漏， 然而’對於表面罩體層27，係形成有爲了攝入爲氧化劑之 空氣的空氣導入口 28,而對於表面罩體層27與空氣極 1 1 1之間’係因應需要而配置保濕層，而保濕層係爲浸含 在空氣極觸媒層13所生成的水之一部分，控制水的蒸發 之同時，促進了對於空氣極觸媒層1 3之空氣的均一擴散 之構成。 然而，構成膜電極接合體16之各層的材料，構成燃 料極密封材19，空氣極密封層20，表面罩體層27等之材 料，係爲與對應於構成前述之一實施型態的燃料電池i 〇 之各自的材料相同。 對於膜電極接合體1 6之燃料極側，係配置有燃料分 配機構1 3 0，而對於燃料分配機構1 3 0係介由如配管之燃 料的流路1 3 1而連接燃料收容部1 3 2。 對於燃料收容部1 3 2，係收容有對應於膜電極接合體 1 6之液體燃料F，作爲液體燃料F係可舉出各種濃度之甲 醇溶液或純甲醇等之甲醇燃料，而液體燃料F係未必爲侷 限於甲醇燃料之構成’而液體燃料F係例如亦可爲乙醇水 溶液或純乙醇等之乙醇燃料，丙醇水溶液或純丙醇等之丙 醇燃料，乙二醇水溶液或純乙二醇等之乙二醇燃料，二甲 醚，犠酸，其他的液體燃料，無論如何均收容因應燃料電 -20- 200836394 、池100之燃料於燃料收容部132。 對於燃料分配機構1 3 0，係從燃料收容部〗3 2，藉由 流路1 3 1而導入液體燃料F，而流路〗3丨係並非限於燃料 分配機構1 3 0或與燃料收容部1 3 2獨立之配管所構成之構 成’例如，層積燃料分配機構1 3 0與燃料收容部1 3 2而作 爲一體化之情況，亦可爲連結此等之液體燃料的流路，而 燃料分配機構1 3 0係如藉由流路1 3 1而與燃料收容部1 3 2 連接即可。 在此，如圖3所示，燃料分配機構1 3 0係具備具有液 體燃料F藉由流路1 3 1而流入之至少1個的燃料注入口 133 ’和排出液體燃料F或其氣化成分之複數個之燃料排 出口 13 4的燃料分配板1 3 5，另外，如圖2所示，對於燃 料分配板1 3 5的內部，設置有成爲從燃料注入口 1 3 3所引 導之液體燃料F的通路之空隙部136，而複數之燃料排出 口 1 34係各自直接連接於做爲燃料通路而發揮機能之空隙 部 1 3 6。 從燃料注入口 1 3 3導入於燃料分配機構1 3 0之液體燃 料F係流入於做爲燃料通路而發揮機能之空隙部1 3 6，並 藉由空隙部136，各自導入至複數之燃料排出口 134，而 對於複數之燃料排出口 1 34係亦可配置例如，只透過燃料 之氣化成分，而不使液體成分透過之氣液分離膜（未圖示） ，由此，對於膜電極接合體1 6之燃料極1 1 0係供給燃料 之氣化成分，然而，氣液分離體係亦可做爲氣液分離膜而 設置於燃料分配機構1 3 0與燃料極1 1 0之間，而液體燃 21 - 200836394 料F的氣化成分係從複數之燃料排出口 ；[ 3 4，朝燃料極 1 1 〇而排出。 燃料排出口 1 3 4係呈可供給燃料於膜電極接合體j 6 之全體地，複數設置於與燃料分配板丨3 5之燃料極丨丨〇接 觸的面’而燃料排出口 1 3 4之個數係如爲2個以上即可， 但爲了將針對在膜電極接合體1 6之面內的燃料供給量作 爲均一化，呈存在有0.1〜10個/cm2之燃料排出口 134地 形成情況則爲理想。 對於連接燃料分配機構1 3 0與燃料收容部1 3 2之間的 流路1 3 1係插入有閥1 3 7，而其閥1 3 7係並非爲循環液體 燃料F之循環閥，而爲從燃料收容部丨3 2移送液體燃料ρ 於燃料分配機構1 3 0的燃料供給閥，經由如此閥i 3 7在必 要時，輸送液體燃料F之情況，提升燃料供給量之控制性 ’此情況，作爲閥1 3 7係可控制性佳地輸送少量的液體燃 料F ’更加地從可小型輕量化的觀點，理想爲使用旋轉葉 片幫浦，電性浸透流幫浦，隔片幫浦，汲取幫浦之情況， 而fc轉葉片幫浦係爲以馬達使葉片旋轉而進行輸送的構成 ’電性浸透流幫浦係爲使用引起電性浸透流現象之二氧化 矽等之燒結多孔體之構成，隔片幫浦係爲經由電磁石或壓 電陶瓷而驅動隔片進行輸送的構成，汲取幫浦係壓迫具有 柔軟性之燃料流路的一部分，汲取液體燃料F而進行輸送 的構成，而在此之中’從驅動電力或尺寸等之觀點，更理 想爲使用電性浸透流幫浦或具有壓電磁石之隔片幫浦者。 針對在如此構成，收容於燃料收容部1 3 2之液體燃料 -22- 200836394 F係經由閥1 3 7而移送至流路1 3 1，再供給至燃料分配機 構1 3 0，並且從燃料分配機構1 3 0所釋放之燃料係供給至 膜電極接合體16之燃料極11〇，而之後的作用係爲與在前 述之燃料電池1 〇之作用相同。 然而，如爲進行從燃料分配機構1 3 0對於膜電極接合 體1 6之燃料供給的構成’亦可取代閥丨3 7，而可做爲配置 燃料遮斷閥之構成者，此情況，燃料遮斷閥係爲了控制經 由流路1 3 1之液體燃料F的供給而加以設置。 針對在具有具備其膜電極接合體1 6之其他構成的燃 料電池100，亦得到與在前述之一實施型態的燃料電池10 之作用效果同樣的作用效果。 接著，針對在將燃料極氣體擴散層1 2之氣孔率係做 爲較空氣極氣體擴散層1 4之氣孔率爲小所設定，及/或將 燃料極觸媒層11之氣孔率係做爲較空氣極觸媒層13之氣 孔率爲小所設定之燃料電池1 〇，由以下之實施例，說明得 到優越輸出特性之情況。 (實施例1) 如以下製作有關本發明之燃料電池。 首先，將碳纖維紙（TOR A Y公司製TGP_ H-120)，由平 板加壓，朝厚度方向，壓縮厚度至成爲1/2爲止，然而， 其碳纖維紙之壓縮前的氣孔率係由使用阿基米德法而測定 時，爲75%，另外，其碳纖維紙之壓縮後的氣孔率係經由 外型尺寸與測定重量計算的結果，爲40.5%，將其碳纖維 -23- 200836394 紙，做爲燃料極氣體擴散層而使用。 接著，由均化器混合載持白金釕合金粒子的碳粒子與 DE2020(DUPONT公司製）而製作漿劑，並將其塗佈於爲燃 料極氣體擴散層之壓縮加壓之碳纖維紙（TORAY公司製 TGP-H-120)之一方的面，並且，將其進行常溫乾燥而形成 燃料極觸媒層，製作燃料極，而其燃料極觸媒層之氣孔率 ~ 係由塗膜尺寸與材料密度，以及測定重量而計算的結果， • 爲 74.2%。 另外，由均化器混合白金載持石墨粒子與DE2020 (DUPONT公司製）而製作漿劑，並將其塗佈於爲空氣極氣 體擴散層之氣孔率爲75%之碳纖維紙（TORAY公司製TGP-H-120)之一方的面，並且，以常溫將其乾燥而形成空氣極 觸媒層’製作空氣極，而其空氣極觸媒層之氣孔率係由塗 膜尺寸與材料密度，測定重量而計算的結果，爲88.1%, 然而，上述之材料密度係經由阿基米德法所求得。 • 做爲電解質膜，使用固定電解質膜NafionU2 (DUPONT公司製），並在最初，將其電解質膜與空氣極， ^ 觸媒層成爲電解質膜側地進行重疊將其電解質膜，以溫度 • 爲12〇°C，壓力爲40kgf/cm2之條件進行加壓，接著，於 與重疊電解質膜之空氣極之相反的面，觸媒層成爲電解質 膜側地重疊燃料極，以溫度爲120°C，壓力爲lOkgf/cm2 之條件進行加壓，製作膜電極接合體（MEA)，然而，電極 面積係空氣極，燃料極同時作爲12cm2。 接著’將其膜電極接合體（MEA)，以具有爲了導入空 -24- 200836394 氣及氣化之甲醇之複數開孔的金薄而夾合，形成燃料極導 電層及空氣極導電層。 以樹脂製之2個框體而夾入層積上述之膜電極接合體 (MEA)，燃料極導電層，空氣極導電層之層積體，然而， 對於膜電極接合體之空氣極側與一方之框體之間，膜電極 接合體之燃料極側與另一方之框體之間，係各自夾持橡膠 製之〇環而進行密封。 另外，燃料極側的框體係介由氣液分離膜，經由螺絲 固定於液體燃料收容室，而對於氣液分離膜，係使用厚度 0.2mm之矽薄片，另一方面，對於空氣極側之框體上，係 配置氣孔率爲28%之多孔質板，形成保濕板，而對於其保 濕板上，係配置形成有爲了空氣攝入之空氣導入口（口徑 4mm，口數64個）之厚度爲2 mm之不銹鋼板（SUS3 04)，形 成表面罩體層，經由螺絲緊固而固定。 對於如上述所形成之燃料電池的液體燃料收容室，將 純甲醇注入5m卜以溫度25t，相對濕度50%之環境，從 電流値與電壓値測定輸出之最大値，另外，經由安裝於表 面層之表面的熱電偶，測定燃料電池之表面溫度的最大値 〇 測定的結果，輸出之最大値係爲12.2mW/cm2，燃料 電池之表面溫度的最大値係爲32.4 t。 更加地，經由於燃料電池的液體燃料收容室，注入 15ml純甲醇，將電壓規定爲0.3V進行連續運轉，並測定 電流密度之情況，測定對於連續運轉時間的輸出變化，其 -25· 200836394 結果，60小時後之輸出下降率係爲8.1%，然而，60小時 後之輸出下降率係指在對於針對在運轉開始時間之輸出的 60小時後，較運轉開始時爲下降之輸出的比例。 將其MEA從元件取出，進行切斷，作爲呈可看到剖 面，埋入於樹脂，而關於埋入於其樹脂之MEA，剖面呈平 面地進行硏磨，以電子顯微鏡觀察，從其結果，將燃料極 觸媒層與空氣極觸媒層之厚度，各自作爲1 0點測定，求 得平均厚度，而從其厚度，材料密度及測定重量算出觸媒 層之氣孔率時，燃料極觸媒層爲68.8%，空氣極觸媒層爲 6 2 · 1 %。 (實施例2) 針對在實施例2所使用之燃料電池的製作，首先，由 均化器混合載持白金釕合金粒子的碳粒子與 DE2020(DUPONT公司製）而製作漿劑，並將其塗佈於爲燃 料極氣體擴散層之氣孔率爲75%之碳纖維紙（TORAY公司 製TGP-H_120)之一方的面，並且，以常溫乾燥其而形成 燃料極觸媒層，製作燃料極。 接著，於燃料極觸媒層上，配置PTFE(聚四氟乙烯）薄 板，並於其上方，配置厚度〇.5mm之矽橡膠薄片，由平板 加壓進行壓縮，其結果，燃料極觸媒層的厚度則成爲2/3 程度，燃料極觸媒層之氣孔率係由塗膜尺寸與材料密度， 以及測定重量而計算的結果，爲66.4% ’然而，針對在其 平板加壓，燃料極氣體擴散層之厚度係無變化。 -26- 200836394 接著，由均化器混合白金載持石墨粒子與 DE2020 (DUPONT公司製）而製作漿劑，並將其塗佈於爲空氣極氣 體擴散層之氣孔率爲75%之碳纖維紙（TORAY公司製TGP-H-12 0)之一方的面，並且，以常溫將其乾燥而形成空氣極 觸媒層，製作空氣極，而其空氣極觸媒層之氣孔率係由塗 膜尺寸與材料密度，以及測定重量而計算的結果，爲 87.2%。 做爲電解質膜，使用固定電解質膜 Nafionll2 (DUPONT公司製），將其電解質膜，以空氣極及燃料極， 觸媒塗佈層呈成爲電解質膜側地夾持，並以溫度爲120 °C ，壓力爲40kgf/cm2之條件進行加壓，製作膜電極接合體 (MEA)，然而，電極面積係空氣極，燃料極同時作爲 1 2cm2，而除此之外的構成係爲與實施例1之燃料電池的 構成相同。 另外，輸出之最大値及燃料電池的表面溫度之最大値 及6 0小時後之輸出下降率之測定方法及測定條件係與在 實施例1之測定方法及測定條件相同。 測定的結果，輸出之最大値係爲1 1 .8mW/cm2，燃料 電池之表面溫度的最大値係爲3 1 · 5 °C，另外，6 0小時後 之輸出下降率係爲9.2%。 將其MEA從元件取出，進行切斷，作爲呈可看到剖 面，埋入於樹脂，而關於埋入於其樹脂之MEA，剖面呈平 面地進行硏磨，以電子顯微鏡觀察，從其結果，將燃料極 觸媒層與空氣極觸媒層之厚度，各自作爲1 0點程度測定 -27- 200836394 ，求得平均厚度，而從其厚度’材料密度及測定重量算出 觸媒層之氣孔率時，燃料極觸媒層爲3 8 ·8 %，空氣極觸媒 層爲6 7.4 %。 (實施例3) 針對在實施例3所使用之燃料電池的製作，首先，將 碳纖維紙（TORAY公司製TGP-H-120)，由平板加壓進行壓 縮，而其碳纖維紙之壓縮後的氣孔率係由外形尺寸與測定 重量而計算的結果，爲40.3% ’將其碳纖維紙，作爲燃料 極氣體擴散層而使用，接著，由均化器混合載持白金釕合 金粒子與DE2020(DUPONT公司製）而製作槳劑，並將其塗 佈於爲燃料極氣體擴散層之壓縮加工之碳纖維紙（TORAY 公司製TGP-H-120)之一方的面，並且，將其進行常溫乾 燥而形成燃料極觸媒層，製作燃料極。 接著，於燃料極觸媒層上，配置PTFE(聚四氟乙烯）薄 板，並於其上方，配置厚度0.5mm之砂橡膠薄片，由平板 加壓進行壓縮，其結果，燃料極觸媒層的氣孔率係由塗膜 尺寸與材料密度，以及測定重量而計算的結果，爲65.5% ，然而，針對在其平板加壓，燃料極氣體擴散層之厚度係 無變化。 接著，由均化器混合白金載持石墨粒子與 DE2020 (DUPONT公司製）而製作漿劑，並將其塗佈於爲空氣極氣 體擴散層之氣孔率爲75%之碳纖維紙（TORAY公司製TGP-H-12 0)之一方的面，並且，以常溫將其乾燥而形成空氣極 -28 - 200836394 觸媒層，製作空氣極，而其空氣極觸媒層之氣孔率係由塗 膜尺寸與材料密度，以及測定重量而計算的結果，爲 8 8 · 0 % 〇 做爲電解質膜，使用固定電解質膜 Nafionll2 (DUPONT公司製），將其電解質膜，以空氣極及燃料極， 觸媒塗佈層呈成爲電解質膜側地夾持，並以溫度爲1 2 0 °C ’壓力爲40kgf/cm2之條件進行加壓，製作膜電極接合體 (MEA)，然而，電極面積係空氣極，燃料極同時作爲 1 2cm2，而除此之外的構成係爲與實施例1之燃料電池的 構成相同。 另外，輸出之最大値，燃料電池的表面溫度之最大値 及6 0小時後之輸出下降率之測定方法及測定條件係與在 實施例1之測定方法及測定條件相同。 測定的結果，輸出之最大値係爲1 1 jmW/cm2，燃料 電池之表面溫度的最大値係爲3 1.2 ，另外，6 0 /』、時後; 之輸出下降率係爲8.3 %。 將其MEA從元件取出，進行切斷，作爲呈可看到剖 面’埋入於樹脂，而關於埋入於其樹脂之MEA，剖面呈平 面地進行硏磨’以電子顯微鏡觀察，從其結果，將燃料極 觸媒層與空氣極觸媒層之厚度’各自作爲10點程度測定 ，求得平均厚度，而從其厚度，材料密度及測定重量算出 觸媒層之氣孔率時’燃料極觸媒層爲38.1%，空氣極觸媒 層爲6 9.5 %。 -29. 200836394 (以較例1) 針對在比較例1所使用之燃料電池的構成’係將氣孔 率爲75%之碳纖維紙（TORAY公司製TGP-H-120)使用於燃 料極氣體擴散層以外’係與實施例1之燃料電池的構成相 同。 另外，輸出之最大値，燃料電池的表面温度之最大値 及60小時後之輸出下降率之測定方法及測定條件係與在 實施例1之測定方法及測定條件相同。 測定的結果，輸出之最大値係爲12mW/cm2，燃料電 池之表面溫度的最大値係爲38.6 °C，另外，60小時後之 輸出下降率係爲20.5%，另外，在比較例1所使用之燃料 電池中，燃料之消耗快，液體燃料收容室之燃料置消耗完 爲止的時間短。 將其MEA從元件取出，進行切斷，作爲呈可看到剖 面，埋入於樹脂，而關於埋入於其樹脂之MEA，剖面呈平 面地進行硏磨，以電子顯微鏡觀察，從其結果，將燃料極 觸媒層與空氣極觸媒層之厚度，各自作爲1 〇點程度測定 ，求得平均厚度，而從其厚度，材料密度及測定重量算出 觸媒層之氣孔率時，燃料極觸媒層爲69.2%，空氣極觸媒 層爲6 3 . 3 %。 (實施例及比較例之測定結果的檢討） 對於表1係表示上述之實施例1〜實施例3及比較例1 之測定結果。 -30- 200836394 〔表1〕 輸出之最大値、 mW/cm2 表面溫度的最大値、 °C 60小時後之輸出下降率、 % 實施例1 12.2 32.4 8.1 實施例2 11.8 31.5 9.2 實施例3 11.7 31.2 8.3 比較例1 12 38.6 20.5 • 從表1所示之測定結果，輸出之最大値係實施例1〜實 施例3及比較例1同時並無極大的差，另外，燃料電池之 表面溫度的最大値係針對在比較例1的溫度則若干高，但 針對在實施例1〜實施例3之溫度，並無很大的差。 60小時後之輸出下降率係表示比較例1較實施例 實施例3爲大的値，而針對在比較例1，60小時後之輸出 下降率爲高的情況係認爲因在比較例1之燃料電池中，從 空氣極側透過於燃料極側的水之一部分則通過液體燃料收 ® 容室，成爲水蒸氣，透過氣液分離膜而流入液體燃料收容 室內，而液體燃料收容室內之甲醇濃度則下降，另一方面 ^ ，針對在有關本發明之實施例1〜實施例3，60小時後之輸 、 出下降率爲低之情況係認爲在實施例1〜3之燃料電池中， 因由將燃料極氣體擴散層之氣孔率做爲較空氣極氣體擴散 層之氣孔率爲小而設定之情況，及/或將燃料極觸媒層之 氣孔率做爲較空氣極觸媒層之氣孔率爲小而設定之情況’ 控制從空氣極側透過於燃料極側之水的一部分’通過燃料 極氣體擴散層之情況，進而抑制液體燃料收容室內之甲醇 31 - 200836394 濃度之下降’另外，了解到針對在有關本發明之燃料電池 ，可得到優越之輸出特性。 然而’結果係雖無表記，但針對在實施例1〜實施例3 S比較例1之燃料電池，在於燃料極導電層之液體燃料收 容室側的表面，設置由具有疏水性之聚四氟乙烯而成之多 ?L Μ情況’亦得到表示與針對在上述各實施例及比較例之 輸出最大値，燃料電池之表面溫度的最大値及60小時後 之輸出下降率之測定結果同樣傾向之測定結果。 另外，在此係表示使用被動型DMFC之一例，但並不 侷限於被動型，而如爲在燃料極側利用經由反應而生成的 水之構造的構成，對於任何燃料電池之方式，並無限定。 然而，本發明並非限定於上述實施形態之構成，而在 實施階段，在不脫離其宗旨之範圍，可將構成要素作爲變 形而具體化，另外，經由揭示於上述實施形態之複數構成 要素的適宜之組合，可形成各種發明，例如，可從表示於 實施形態之全構成要素刪除幾個構成要素，更加地亦可適 宜組合遍佈不同實施形態的構成要素 。 另外，針對在供給於膜電極接合體（MEΑ)之液體燃料 的蒸氣，亦可完全供給液體燃料的蒸氣，但在以液體狀態 供給一部分之情況，亦可適用本發明。 [產業上之利用的可能性] 如根據有關本發明之型態的燃料電池，由將燃料極氣 體擴散層之氣孔率，做爲較空氣極氣體擴散層之氣孔率爲 -32» 200836394 小所設定之情況，及/或將燃料極觸媒層之氣孔率，做爲 較空氣極觸媒層之氣孔率爲小所設定之情況，可將在空氣 極所生成的水儲存於燃料極內，進而控制從燃料極氣體擴 散層，其水浸入於液體燃料收容室側者，由此，可控制由 燃料極氣體擴散層，在液體燃料收容室側產生之燃料濃度 之下降，進而可對於燃料極觸媒層供給特定之濃度燃料， w 故可抑制經由連續運轉之燃料電池的輸出下降，而有關本 Φ 發明之型態的燃料電池係例如有效地利用於液體燃料直接 供給型之燃料電池等。 【圖式簡單說明】 [圖1 ]係爲模式性地表示有關本發明之一實施型態之 直接甲醇型的燃料電池剖面的圖。 [匱I 2]係爲模式性地表示有關本發明之一實施型態之 其他構成之直接甲醇型的燃料電池剖面的圖。 • 3]係爲模式性地表示燃料分配機構之構成斜視圖 【主要元件符號說明】 I ·燃料電池 10 0 :燃料電池 II :燃料極觸媒層 12 ·燃料極氣體擴散層 13:空氣極觸媒層 -33- 200836394 1 4 :空氣極氣體擴散層 15 :電解質膜 1 6 :膜電極接合體 1 7 :燃料極導電層 1 8 :空氣極導電層 1 9 :燃料極密封材 20 :空氣極密封材 2 1 :液體燃料收容室 22 :氣液分離膜 2 3，2 5 :框體 24 :氣化燃料收容室 2 6 :保濕層 27 :表面罩體層 28 :空氣導入口 F :液體燃料 1 3 0 :燃料分配機構 1 3 1 :流路 1 3 2 :燃料收容部 1 3 3 :燃料注入口 134 :燃料排出口 1 3 5 :燃料電池分配板 1 3 6 :空隙部 137 :閥 -34200836394 IX. Description of the Invention [Technical Field] The present invention relates to a fuel cell, particularly a small liquid fuel direct supply type fuel cell. [Prior Art] In recent years, with the advancement of electronic technology, the miniaturization of electronic equipment, the high φ performance, and the portability have continued to progress, and the high energy density of batteries used in portable electronic equipment is strongly demanded. Therefore, a lightweight and compact battery requires a high-capacity secondary battery. For the requirements of such a secondary battery, for example, a lithium ion secondary battery has been developed. In addition, the operating time of the portable electronic device has a tendency to increase more, and among lithium ion secondary batteries, from the material From the point of view, as well as the point of view of the structure, the increase in energy density almost reached the limit, and it became impossible to respond to more requirements. Φ According to such a situation, a small-sized fuel cell is attracting attention instead of a lithium ion secondary battery, and in particular, a direct methanol fuel cell (DMFC) using methanol as a fuel is compared with hydrogen. The fuel cell, the difficulty in the place of hydrogen, or the device for producing hydrogen without modifying the organic fuel, is superior to miniaturization. In D MFC, methanol is oxidized and decomposed at the fuel electrode to generate carbon dioxide, protons and electrons. On the other hand, in the air electrode, oxygen is obtained from the air, and is supplied from the fuel through the electrolyte membrane. The protons and the electrons supplied from the fuel electrode through the external circuit generate water. -5-200836394 In addition, the electric power is supplied to the DMFC system through the electrons passing through the external circuit. The valve or the air that is sent into the air constitutes a complicated type of DMFC, so it is not easy to achieve miniaturization in the middle. Therefore, instead of supplying methanol by a valve, a membrane of a molecule passing through methanol is provided between the methanol elements instead of being brought close to the vicinity of the power generation element by the valve, and, for example, for the publication of WO2005/1 12 1 72 In the introduction of air, a small DMFC is constructed by installing a direct air intake port without using a bellows. However, if J replaces the simplified mechanism and receives external conditions such as temperature, a certain amount of methanol is transmitted to the power generating element. Therefore, it is difficult to stabilize the output and the high-volume situation. In addition, in order to control the supply amount of such methanol, the porous body is disposed between the fuels, In the above-described conventional fuel cell configuration, the water generated by the reaction is mixed with fuel, burned, and a certain concentration of fuel is supplied to the power generating element. The situation is difficult. [Patent Document 1] WO 200 5/1 1 2 1 72 publication [Patent Document 2] Japanese Patent Laid-Open No. 2004- 1 7 1 844 is used to generate electricity, and is used as a box to develop a DMFC storage chamber and power generation. Methanol, and the miniaturization of the system is not difficult to install on the power generation component t[: the DMFC system is difficult, the report reveals that the capacitive part and the negative electrode replace the simplified machine concentration The decrease is not easy, because it is reported -6-200836394 [Summary of the Invention] θ it 'The object of the present invention is to provide a controllable reduction in fuel concentration while at the same time 'can supply fuel to the fuel extreme, and can be used continuously for a long time. The fuel cell of the stable output. According to one aspect of the present invention, a fuel electrode including a fuel electrode layer and a fuel electrode gas diffusion layer provided on a surface facing one of the fuel electrode catalyst layers has an air electrode catalyst layer and a surface An air electrode of the air electrode diffusion layer provided on one of the surfaces of the air electrode catalyst layer and a film electrode formed by the electrolyte film sandwiched between the fuel electrode catalyst layer and the air electrode catalyst layer The fuel cell of the present invention, wherein the fuel cell diffusion layer has a porosity which is smaller than a porosity of the air electrode diffusion layer. Further, according to an aspect of the present invention, there is provided a fuel electrode including a fuel electrode layer and a fuel electrode gas diffusion layer provided on a surface facing one of the fuel electrode catalyst layers, and an air electrode catalyst layer And an air electrode of the air electrode gas diffusion layer provided on a surface of one of the air electrode catalyst layers, and a film formed of an electrolyte membrane sandwiched between the fuel electrode catalyst layer and the air electrode catalyst layer In a fuel cell of an electrode assembly, a fuel cell in which a porosity of the fuel electrode catalyst layer is smaller than a porosity of the air electrode catalyst layer is provided. Further, according to one aspect of the present invention, there is provided a fuel electrode including a fuel electrode layer and a fuel electrode gas diffusion layer provided on a surface facing one of the fuel electrode catalyst layers, and an air electrode catalyst And an air electrode of the layer of the air gas diffusion layer disposed on the surface facing the one of the air electrode catalyst layers, and an electrolyte film sandwiched between the fuel electrode catalyst layer and the air electrode catalyst layer a fuel cell of a membrane electrode assembly, wherein a porosity of the fuel electrode diffusion layer is smaller than an air control ratio of the air electrode diffusion layer, and a porosity of the fuel electrode layer is higher than the foregoing The fuel cell of the air extreme catalyst layer has a small porosity. Further, the fuel cell of the present invention may further include a liquid fuel storage chamber for accommodating the liquid fuel, and having an opening for deriving the vaporization component of the liquid fuel, and an opening for sealing the liquid fuel storage chamber; The vapor-liquid component of the liquid fuel is passed through the gas-liquid separation membrane that is passed through the fuel electrode gas diffusion layer of the fuel electrode. Further, the fuel cell of the present invention may further include a fuel distribution mechanism disposed on a fuel electrode side of the membrane electrode, and a fuel distribution mechanism that supplies fuel to the fuel electrode gas diffusion layer of the fuel electrode, and a liquid fuel. a fuel accommodating portion to which the fuel distribution mechanism and the flow path are connected. [Embodiment] [Best Mode for Carrying Out the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a view schematically showing a direct methanol-shaped fuel cell 1 有关 according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell 1 is provided with a fuel electrode including a fuel electrode catalyst layer 1 1 and a fuel electrode gas diffusion layer 12 as an electrification portion, and an air electrode catalyst layer 13 and air. The gas electrode 8 - 200836394 formed by the gas diffusion layer 14 is composed of an electrolyte membrane 15 which is proton (hydrogen ion) conductive between the fuel electrode layer 11 and the air catalyst layer 13 Membrane Electrode Assembly (MEA: Membrane Electrode Assembly) 16 〇 The catalyst system contained in the fuel electrode catalyst layer 1 1 and the air electrode catalyst layer 13 may be, for example, a platinum group element Pt, Pu, Rh, Ir. , a monomer metal such as Os, Pd, an alloy containing a platinum group element, or the like. Specifically, as the fuel electrode catalyst layer 1, it is desirable to use Pt-Ru or Pt which is highly resistant to methanol or carbon monoxide. In the case of -Mo, etc., it is preferable to use platinum or Pt-Ni as the air electrode catalyst layer 13, but it is not limited to such a configuration, and it is also possible to use a conductive carrier such as a carbon material. The carrier of the body or the inorganic carrier catalyst. In addition, the fuel electrode catalyst layer 1 1 and the air electrode catalyst layer 13 have a specific porosity, and the porosity of the fuel electrode catalyst layer 1 is the porosity of the air electrode catalyst layer 13 . Specifically, the porosity of the fuel electrode catalyst layer 1 is 20 to 80%, preferably 40 to 70%, more preferably 50 to 70, of the porosity of the air electrode catalyst layer 13 . Here, the ratio of the porosity of the fuel electrode catalyst layer 1 to the porosity of the air-electrode catalyst layer 13 is regarded as a range thereof, and the ratio is smaller than 20%. The methanol fuel permeability of the fuel electrode catalyst layer 1 itself is lowered, but the reforming reaction is not promoted, and in the case where the ratio is 80%, the vaporized methanol fuel passes through the fuel electrode catalyst layer. 1 and also overlap with the air electrode catalyst layer 13 through the electrolyte membrane 15, causing an unnecessary reaction to lower the output potential, and on the other hand, the water passing through the electrolyte membrane 15 passes through the fuel. The gas diffusion layer 1 2, after -9 - 200836394, is vaporized and mixed into the liquid fuel containment chamber 2 1 . The proton conductive material constituting the electrolyte membrane 15 is, for example, a fluorocarbon resin having a sulfonic acid group, for example, a perfluoroxanthate polymer (Nafion (trade name, manufactured by DuPont), Flemion (trade name) (available from Asahi Glass Co., Ltd.), a hydrocarbon resin having a sulfonic acid group, an inorganic substance such as tungstic acid or phosphotungstic acid, or the like, but is not limited thereto. The anode gas diffusion layer 25 laminated on the anode catalyst layer 24 performs the function of uniformly supplying the fuel to the anode catalyst layer 24, and also has the collector of the anode catalyst layer 24, and is laminated on the cathode catalyst. The cathode gas diffusion layer 27 of the layer 26 performs the function of uniformly supplying the oxidant to the cathode catalyst layer 26, and also serves as the current collector of the cathode catalyst layer 26. Further, since the fuel electrode gas diffusion layer 12 and the air electrode gas diffusion layer 14 are made of a gas, a known conductive material made of a porous body is formed, and the fuel electrode gas diffusion layer 12 and air are formed. The polar gas diffusion layer 14 is made of, for example, carbon fiber paper or carbon fiber woven fabric, but is not limited to such a configuration. For example, the fuel electrode gas diffusion layer 12 or the air electrode gas diffusion layer 14 is preferably made of an adjustable The material of the porosity ratio is composed of, for example, a carbon fiber paper having a volume which is compressed, that is, a density change, and the porosity of the fuel electrode gas diffusion layer 12 is preferably a gas diffusion layer. Specifically, the porosity of the fuel electrode gas diffusion layer 12 is 20 to 80% of the porosity of the air electrode gas diffusion layer 14, and is preferably 40 to 7 〇 ° / ❶. More preferably, it is 50 to 70%, and the ratio of the porosity of the fuel electrode gas diffusion layer 12 to the porosity of the air electrode gas diffusion layer 14 is taken as the range thereof. Its proportion is smaller than 20% In this case, it is difficult to supply an appropriate amount of vaporized fuel to the fuel electrode catalyst layer 1 by the fuel electrode diffusion layer 12, and it is difficult for the ratio to be 80% larger. The methanol fuel is excessively supplied to the fuel electrode catalyst layer, and the excess methanol fuel passes through the fuel electrode catalyst layer 1 and also passes through the electrolyte membrane 15 to overlap the air electrode catalyst layer 13 . On the other hand, the water that has passed through the electrolyte membrane 15 passes through the fuel electrode gas diffusion layer 12, and then vaporizes and is mixed into the liquid fuel storage chamber 21. However, in the case where the porosity of the fuel electrode catalyst layer 1 is set to be smaller than the porosity of the air electrode catalyst layer 13, the porosity of the fuel electrode gas diffusion layer 12 can also be made. It is set to be smaller than the porosity of the air electrode diffusion layer 14 . Further, for the fuel electrode gas diffusion layer 12, the fuel electrode conductive layer 17 is laminated, and for the air electrode gas diffusion layer 14, the air electrode conductive layer 18 is laminated, and the fuel electrode conductive layer 17 and the air electrode conductive layer are laminated. The 18-series is preferably a porous layer (for example, a metal mesh) or a foil obtained by using a metal such as platinum, gold or the like, or a metal such as nickel or stainless steel, or a gold foil. Or a conductive material of carbon fiber, a material which is surface-treated with a dissimilar metal, a composite material of a good conductive metal such as gold coated with copper or stainless steel, and a fuel electrode conductive layer 17 and an air electrode conductive layer 18 are It does not constitute a leak from such a periphery, fuel or oxidant. -11 - 200836394 In addition, the fuel electrode conductive layer 17 and the electrolyte membrane 15 are disposed between the fuel electrode catalyst layer 11 and the fuel electrode gas diffusion layer 12 while having a rectangular frame-shaped fuel electrode sealing material 19 Between the 'other side' air-electrode conductive layer 18 and the electrolyte membrane 15, a rectangular electrode-shaped air electrode sealing material 20 is disposed, and the air electrode catalyst layer 13 and the air electrode gas diffusion layer 14 are enclosed. The fuel electrode sealing material 19 and the air electrode sealing material 20 are formed of, for example, a rubber ring or the like, and prevent fuel leakage from the membrane electrode assembly 16 and oxidant leakage, but the 'fuel electrode sealing material 19' The shape of the air electrode sealing material 20 is not limited to the rectangular shape, and is configured to correspond to the outer edge shape of the fuel cell 1 . In addition, as shown in FIG. 1, the gas-liquid separation membrane 22 is disposed in the opening of the liquid fuel storage chamber 21 in which the liquid fuel F is replenished, and the gas-liquid separation membrane 22 is disposed on the gas-liquid separation membrane 22 corresponding to the fuel cell 1. a frame body 23 (in this case, a rectangular frame body) having a shape of the outer edge of the crucible, and the fuel electrode conductive layer 17 is laminated on the frame body 23 in the frame body 23, and is provided with the above-mentioned The membrane electrode assembly 16 of the fuel electrode conductive layer 17 and the air electrode conductive layer 18, wherein the frame body 23 is made of an electrically insulating material, specifically, for example, polyethylene terephthalate (for example) PET) is formed by a thermoplastic polyester resin or the like. In addition, the liquid fuel F stored in the liquid fuel container 21 is a methanol aqueous solution having a concentration of more than 50% by mole, or pure methanol, and the purity of pure methanol is preferably 95% by weight or more and 100% by weight or less, and the liquid is further The gasification component of the fuel F means that the methanol which is liquid is used as the liquid fuel F means methanol which is vaporized, and the case where the methanol aqueous solution is used as the liquid -12-200836394 fuel F means the gasification component of methanol. Mixed with a gasified component of water. In addition, the vaporized fuel storage chamber 24 in the space surrounded by the gas-liquid separation membrane 22, the fuel electrode conductive layer 17, and the frame 23 temporarily stores the vaporized component of the liquid fuel F that has passed through the gas-liquid separation membrane 22. In addition, it is to be able to function as a uniform space for the concentration distribution of the fuel in the gasification component. φ In addition, the gas-liquid separation membrane 22 is configured to separate the vaporized component of the liquid fuel F from the liquid fuel F and to pass the vaporized component thereof to the fuel electrode catalyst layer 1 side, and the gas-liquid separation membrane thereof. For the liquid fuel F, the 22-series is made of a material which is inactive and insoluble, and is formed into a thin plate shape, specifically, a ruthenium rubber, a low density polyethylene (LDPE) film, a polyvinyl chloride (PVC) film, a poly pair. A material such as a polyethylene terephthalate (PET) film or a microporous film such as a fluorocarbon resin (for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene, perfluoroalkyl vinyl ether copolymer (PFA), etc.) Composition. Φ On the other hand, the air electrode conductive layer 18 is laminated by a frame body 25 (here, a * rectangular frame) which is formed in a shape corresponding to the outer edge shape of the fuel cell 10 The moisture-retaining layer 26 is further provided with a function as a surface layer on the moisture-retaining layer 26, and a surface cover layer 27 in which a plurality of air introduction ports 28 for introducing air into an oxidant are laminated, and a surface cover layer thereof is formed. Since the laminate of the film-electrode assembly 16 is pressurized, the adhesion of the membrane electrode assembly 16 is also promoted. Therefore, for example, it is formed of a metal such as SU S3 04, and the frame 25 is similar to the frame 23 . It is composed of an electrically insulating material, and is specifically formed of, for example, a thermoplastic polyester resin such as polyethylene terephthalate-13-200836394 (PET). Further, the moisturizing layer 26 is impregnated with a portion of the water generated in the air-electrocatalyst layer 13 to constitute an effect of controlling the evaporation of water while uniformly introducing the oxidant into the air-polar gas diffusion layer 14 by the oxidizing agent. 'There is also a function as a supplementary diffusion layer for promoting uniform diffusion of the oxidant of the air-electrode catalyst layer 13, and the moisture-retaining layer 26 is composed of, for example, a material such as a polyethylene porous film, and uses the largest one. The pore size is a film of 20 to 50 degrees, and the case where the largest pore diameter is used as the range is smaller than the case where the pore diameter is smaller than 20 W, because the air permeability is decreased, and it is larger than 50. In this case, the evaporation of water is excessive, however, the movement of the water from the side of the air electrode catalyst layer 13 to the fuel cell layer 1 through the soaking pressure phenomenon can be changed for the surface provided on the moisture layer 26. The number of air inlets 28 of the cover layer 27 is controlled by the number or size of the air inlets, and the area of the openings is adjusted. However, the configuration of the fuel cell 10 is not limited to the above-described constituents. For example, a hydrophobic porous film may be provided between the fuel electrode conductive layer 17 and the frame 23, and the porous film may be provided. In this case, it is possible to prevent intrusion of water from the fuel gas diffusion layer 12 side of the porous film to the vaporized fuel storage chamber 24 side as a material of a specific porous film, for example, polytetrafluoroethylene (PTEF), as a thin plate or the like for the hydration treatment, the gas-liquid separation membrane 22 has a gas-liquid separation function similar to that of the gas-liquid separation membrane 22, and further has a gas-liquid separation function. It is also possible to provide a permeation amount adjustment film for adjusting the permeation amount of the fuel gasification component of the fuel, and the adjustment of the permeation amount of the vaporization component of the permeation amount adjustment film is adjusted by the adjustment of the permeation amount adjustment film. The diameter of the hole portion is increased, and the permeation amount adjusting film is made of a material such as polyethylene terephthalate. The film is adjusted by the amount of the permeation amount, and the supply to the fuel cell layer 11 can be adjusted. Side fuel gas Those components of the feed rate. Next, regarding the action of the above-described fuel cell 100, the description will be made. The liquid fuel F (for example, an aqueous methanol solution) in the fuel accommodating portion 2 1 is vaporized and the vaporized methanol and water vapor are passed through the gas-liquid separation membrane 22 and temporarily stored in the vaporized fuel storage chamber 24 . The concentration distribution is uniformly performed, and the mixed gas temporarily accommodated in the vaporized fuel storage chamber 24 is further diffused by the fuel electrode diffusion layer 12 through the fuel electrode conductive layer 12 and supplied to the fuel electrode catalyst layer 1 1. The mixed gas supplied to the fuel electrode catalyst layer 11 generates an internal reforming reaction of methanol represented by the following formula (1). • CH30H + H20—C02 + 6H + + 6e-···· (1) " However, in the case where pure methanol is used as the liquid fuel F, since the water vapor is not supplied from the liquid fuel container 21, it is in the air. The water generated in the catalyst layer 13 or the water in the electrolyte membrane 15 generates an internal reforming reaction of the above formula (1) with methanol, or does not pass through the internal reforming reaction of the above formula (1), and Other reaction mechanisms of water produce internal reforming reactions. The proton (H + ) generated by the internal reforming reaction is conducted in the electrolyte membrane 15 and reaches the air-electrode catalyst layer 13, and the air taken in from the air -15-200836394 gas introduction port 28 of the surface cover layer 27 Dispersing in the moisture layer 26, the air electrode conductive layer 18, the air electrode gas diffusion layer 14, and the air system supplied to the air electrode catalyst layer u's other to the air electrode catalyst layer 13 produces the next (2) In the reaction shown, water is generated to generate a power generation reaction according to the reaction (3/2) 02 + 6H + + 6e - 3 Η 20 · " (2) is formed in the air electrode catalyst layer 13 by the reaction thereof. The water in the system diffuses in the air electrode diffusion layer 14 and reaches the moisture layer 26, and a part of the water is evaporated from the air introduction port 28 of the surface cover layer 27 provided on the moisture layer 26, and the remaining water system Temporarily stored in the moisture retaining layer 26, reaches the air electrode catalyst layer 13 through the air electrode gas diffusion layer 14, and more, when the reaction of the formula (2) is performed, the amount of generated water increases, and the air is extremely catalytic. The amount of water stored in layer 13 is increased, for this case, accompanied by formula (2) When the reaction proceeds, the amount of water stored in the air electrode catalyst layer 13 is greater than the amount of water stored in the fuel electrode layer 1 1 , and as a result, it is generated in the air electrode catalyst layer 1 by the penetration phenomenon. The water of 3 promotes the phenomenon of moving to the fuel electrode catalyst layer 1 through the electrolyte membrane 15 , and therefore, the supply of moisture to the fuel electrode catalyst layer 1 is compared with that of only the liquid fuel container 21 . In the case of the water vapor, the supply of water is promoted, and the internal reforming reaction of the methanol of the above formula (1) can be promoted. In addition, generally, part of the water that has passed through the fuel electrode side from the air electrode side passes through the fuel electrode gas diffusion layer 12, and the water vapor "passes through the gas-liquid separation membrane 22 and flows into the liquid fuel storage chamber 21, and flows in. When the amount of water in the fuel containing chamber 21 is large, the liquid concentration in the liquid fuel containing chamber 21 is lowered, and as a result, the methanol supply to the fuel electrode catalyst layer 1 is caused. However, in the present invention, the porosity of the fuel electrode gas diffusion layer 12 is set to be lower than the porosity of the air electrode gas diffusion layer 14 due to the low porosity. The water of the membrane 15 does not pass through the fuel electrode diffusion layer 12, so that the fuel concentration generated by the fuel gas diffusion layer 12 on the liquid fuel storage chamber 21 side is controlled, and in the fuel electrode, Since the water in the reaction of the formula (2) can be stored, the chemical reaction with the methanol vaporized by the fuel electrode diffusion layer 12 can be maintained, and therefore, the stable output density can be maintained for a long period of time. . On the other hand, in the case of the air electrode, it is necessary to take in more air from the air catalyst layer 13 in the air, and in the present invention, the porosity of the fuel electrode gas diffusion layer 12 is used as the air electrode. When the porosity of the gas diffusion layer 14 is set to be low, a sufficient amount of oxygen is supplied to the reaction of the above formula (2), whereby the stable output density can be maintained for a long period of time. Further, as the liquid fuel F, even when a methanol aqueous solution having a methanol concentration of more than 50 mol% or pure methanol is used, water moving from the air electrode catalyst layer 13 to the fuel electrode catalyst layer 1 can be used. Since the internal reforming reaction is carried out, the supply of water to the fuel electrode catalyst layer 1 can be stabilized, thereby further reducing the reaction resistance of the internal reforming reaction of methanol, thereby further improving long-term output and load current. Further, in addition, it is also possible to reduce the size of the liquid fuel storage chamber 21 . -17- 200836394 However, here, the case where the porosity of the fuel electrode diffusion layer 12 is set to be smaller than the porosity of the air electrode diffusion layer 14 has been described, but The same effect can be obtained by setting the porosity of the fuel electrode catalyst layer 11 to be smaller than the porosity of the air electrode catalyst layer 13. Further, the fuel gas diffusion layer 12 is further obtained. The porosity is set to be smaller than the porosity of the air electrode diffusion layer 14, and the porosity of the fuel electrode layer 11 is set to be smaller than the porosity of the air catalyst layer 13. In the same situation, the same effect is obtained. According to the above, the direct methanol type fuel cell 10 according to the embodiment is configured such that the porosity of the fuel electrode gas diffusion layer 12 is set to be smaller than the porosity of the air electrode diffusion layer 14, and/ Or the porosity of the fuel electrode catalyst layer 11 is set to be smaller than the porosity of the air electrode catalyst layer 13, and the water generated in the air electrode can be stored in the fuel electrode. The fuel gas diffusion layer 12 can be controlled to invade the liquid fuel storage chamber 21 side, and thus, the fuel gas diffusion layer 12 can be controlled to be generated on the liquid fuel storage chamber 21 side. When the fuel concentration is lowered, a fuel of a specific concentration can be supplied to the fuel electrode catalyst layer 1, so that the output of the fuel cell that has been continuously operated can be suppressed from being lowered. Further, the porosity of the fuel electrode gas diffusion layer 12 is set to be smaller than the porosity of the air electrode diffusion layer 14 and/or the porosity of the fuel electrode catalyst layer 1 is In the case where the porosity of the air-based catalyst layer 13 is set to be small, it is possible to supply a sufficient amount of oxygen to the reaction generated in the air-electrocatalyst layer 13 and, by this, it is also possible to suppress the continuous operation. - 200836394 Turn the output of the fuel cell to drop. However, in the above-described embodiment, the direct methanol type fuel cell in which the methanol solution or the pure methanol is used as the liquid is described, but the liquid fuel is not limited thereto, and may be an example solution or ethanol such as pure ethanol. a fuel, an aqueous solution of propanol or a pure propanol fuel, an ethylene glycol aqueous solution such as ethylene glycol or pure ethylene glycol, or a liquid fuel, or any other liquid fuel, which in any case contains a liquid fuel of a battery, and a fuel cell system The present invention can also be applied to a semi-fuel cell using a valve or the like for a part of a fuel cell or the like, and the same effects as those in the case of using a fuel cell can be obtained. Next, the other configuration 2 and the direct methanol type fuel cell including the above-described membrane electrode assembly 16 will be described. Η 2 is a schematic diagram showing a cross section of a direct methanol type fuel cell constructed by one of the embodiments of the present invention, schematically showing a configuration of the fuel distribution mechanism i 3 〇, and one of the above The configuration of the fuel cell of the embodiment is the same as that of the same reference numerals, and the description is omitted or simply repeated. As shown in FIG. 2, the membrane electrode assembly 16 is a fuel electrode formed of a fuel electrode crucible and a fuel electrode gas diffusion layer i 2 , and an air electrode formed by the air 13 and the air electrode gas diffusion layer 14 . The proton between the polar catalyst layer 11 and the air catalyst layer 13 (conducting electrolyte membrane i 5 is formed. The body fuel is made of a fuel such as ethanol hydroalcohol, and the fuel of the dimethyl fuel is electrically passive. Passive type of the present invention, referring to the figure mode of Fig. 3, however, a part of the single-medium layer 1 1 pole catalyst layer is clamped to hydrogen-burning ions) -19-200836394 For the electrolyte membrane 15 Between the fuel distribution mechanism i 3 后 to be described later, the fuel electrode sealing material 1 is interposed, and between the electrolyte membrane 15 and the surface covering layer 27, the air electrode sealing layer 2 is interposed. While preventing fuel leakage or oxidant leakage from the membrane electrode assembly 16 , 'the surface cover layer 27 is formed with an air introduction port 28 for ingesting air as an oxidant, and for the surface cover layer 27 and the air electrode 1 Between 1 and 1 'as needed Moisture retaining layer, and the moisture is infiltrated strata in a portion of the water from the air electrode catalyst layer 13 is generated, the control of the evaporation of the water, while promoting the uniform diffusion of constituting the air electrode catalyst layer of the air 13. However, the material constituting each layer of the membrane electrode assembly 16 constitutes a fuel electrode sealing material 19, an air electrode sealing layer 20, a surface covering layer 27, and the like, and is a fuel cell corresponding to one of the aforementioned embodiments. The materials are the same. The fuel distribution mechanism 130 is disposed on the fuel electrode side of the membrane electrode assembly 16 , and the fuel storage unit 1 3 0 is connected to the fuel storage unit 13 through the flow path 1 3 1 of the fuel such as piping. 2. The fuel accommodating portion 133 accommodates the liquid fuel F corresponding to the membrane electrode assembly 16. The liquid fuel F includes methanol solution of various concentrations or methanol fuel such as pure methanol, and the liquid fuel F system. The liquid fuel F is not necessarily limited to the composition of the methanol fuel, and the liquid fuel F may be, for example, an ethanol fuel such as an aqueous ethanol solution or pure ethanol, a propanol fuel such as an aqueous solution of propanol or pure propanol, or an aqueous solution of ethylene glycol or pure ethylene glycol. Ethylene glycol fuel, dimethyl ether, citric acid, and other liquid fuels are in any case contained in the fuel accommodating portion 132 in response to the fuel -20-200836394 and the fuel of the pool 100. In the fuel distribution mechanism 130, the liquid fuel F is introduced from the fuel accommodating portion 321 via the flow path 133, and the flow path 并非3 is not limited to the fuel distribution mechanism 1300 or the fuel accommodating portion. In the case where the laminated fuel distribution mechanism 130 and the fuel accommodating unit 133 are integrated, for example, a flow path connecting the liquid fuels may be used, and the fuel may be used. The distribution mechanism 130 may be connected to the fuel storage unit 1 3 2 by the flow path 1 3 1 . Here, as shown in FIG. 3, the fuel distribution mechanism 130 includes a fuel injection port 133' having at least one of the liquid fuel F flowing in through the flow path 131, and a liquid fuel F or a vaporized component thereof. A plurality of fuel distribution plates 135 of the fuel discharge port 13 4, and as shown in FIG. 2, a liquid fuel that is guided from the fuel injection port 133 is provided inside the fuel distribution plate 135. The gap portion 136 of the passage of F, and the plurality of fuel discharge ports 134 are each directly connected to the gap portion 136 functioning as a fuel passage. The liquid fuel F introduced into the fuel distribution mechanism 130 from the fuel injection port 133 flows into the gap portion 163 which functions as a fuel passage, and is introduced into the plurality of fuel rows by the gap portion 136. The outlet 134 may be provided with, for example, a gas-liquid separation membrane (not shown) that transmits only the vaporized component of the fuel and does not allow the liquid component to permeate the plurality of fuel discharge ports 134, thereby bonding the membrane electrode The fuel electrode 110 of the body 16 is a gasification component for supplying fuel, however, the gas-liquid separation system may be disposed as a gas-liquid separation membrane between the fuel distribution mechanism 1130 and the fuel electrode 1 1 0, and Liquid burning 21 - 200836394 The gasification component of material F is from a plurality of fuel discharge ports; [3 4, discharged toward the fuel electrode 1 1 〇. The fuel discharge port 134 is provided to supply the fuel to the entire membrane electrode assembly j 6 , and is provided at a plurality of surfaces that are in contact with the fuel electrode 燃料 of the fuel distribution plate 丨 35 and the fuel discharge port 1 3 4 The number may be two or more. However, in order to normalize the amount of fuel supplied to the surface of the membrane electrode assembly 116, there is a presence of 0. 1 to 10 / cm2 of fuel discharge 134 ground formation is ideal. The flow path 133 between the fuel distribution mechanism 130 and the fuel accommodating portion 133 is inserted with a valve 137, and the valve 137 is not a circulation valve for the circulating liquid fuel F. The fuel supply valve of the fuel distribution mechanism 130 is transferred from the fuel accommodating portion 232, and the liquid fuel F is supplied as necessary through the valve i37, thereby improving the controllability of the fuel supply amount. As a valve, the system can control the small amount of liquid fuel F' more easily. From the viewpoint of small size and light weight, it is ideal to use a rotating blade pump, an electric immersion flow pump, a spacer pump, and a snap. In the case of the pump, the fc-rotating blade pump is configured to transmit the blade by rotating the motor. The electric-impregnated flow pump is a sintered porous body using cerium oxide or the like which causes an electrical permeation phenomenon. The spacer pump system is configured to drive the separator through the electromagnet or the piezoelectric ceramic, and draws a part of the flexible fuel flow path which is pumped by the pump, and draws the liquid fuel F to be transported. 'From Size of electricity or the like movable, it is more ideal to use electrically-osmotic-flow pump or the separator magnet of a piezoelectric pump's. With this configuration, the liquid fuel -22-200836394 F accommodated in the fuel accommodating portion 133 is transferred to the flow path 133 via the valve 137, and is supplied to the fuel distribution mechanism 1300, and is distributed from the fuel. The fuel released by the mechanism 130 is supplied to the fuel electrode 11A of the membrane electrode assembly 16, and the subsequent action is the same as that of the fuel cell 1 described above. However, the configuration of the fuel supply to the membrane electrode assembly 16 from the fuel distribution mechanism 130 may be replaced by the valve block 3, and may be used as a component of the fuel shutoff valve. In this case, the fuel The shutoff valve is provided to control the supply of the liquid fuel F via the flow path 131. The fuel cell 100 having the other configuration including the membrane electrode assembly 16 has the same operational effects as those of the fuel cell 10 of the above-described embodiment. Next, the porosity of the fuel electrode diffusion layer 12 is set to be smaller than that of the air gas diffusion layer 14 , and/or the porosity of the fuel electrode layer 11 is used as The fuel cell 1 is set to be smaller than the air cell layer 13 having a small porosity, and the following examples show that superior output characteristics are obtained. (Example 1) A fuel cell according to the present invention was produced as follows. First, carbon fiber paper (TGP_H-120 manufactured by TOR AY Co., Ltd.) is pressed by a flat plate and compressed to a thickness of 1/2 in the thickness direction. However, the porosity of the carbon fiber paper before compression is used by Aki. When measured by the Mead method, it is 75%, and the porosity of the carbon fiber paper after compression is calculated by the external dimension and the measured weight. 5%, its carbon fiber -23-200836394 paper is used as a fuel gas diffusion layer. Next, a carbon particle of the platinum ruthenium alloy particles and a 2020 (manufactured by DUPONT Co., Ltd.) were mixed by a homogenizer to prepare a slurry, which was applied to a carbon fiber paper which was compressed and pressurized as a fuel gas diffusion layer (TORAY Corporation). One side of TGP-H-120), and it is dried at room temperature to form a fuel electrode catalyst layer to form a fuel electrode, and the porosity of the fuel electrode layer is determined by the film size and material density. And the result of the calculation of the weight, • is 74. 2%. In addition, a slurry was prepared by mixing graphite particles and a 2020 (manufactured by DUPONT Co., Ltd.) in a homogenizer, and applied to a carbon fiber paper having a porosity of 75% which is an air gas diffusion layer (TGP manufactured by TORAY Corporation). -H-120) one side of the surface, and drying it at normal temperature to form an air electrode catalyst layer 'making an air electrode, and the porosity of the air electrode catalyst layer is determined by the film size and material density. The result of the calculation is 88. 1%, however, the above material density is obtained by the Archimedes method. • As the electrolyte membrane, a fixed electrolyte membrane NafionU2 (manufactured by DUPONT Co., Ltd.) was used, and at the beginning, the electrolyte membrane was superposed on the electrolyte membrane side with the air electrode and the catalyst layer as the electrolyte membrane side, and the temperature was 12 〇°C, the pressure is 40 kgf/cm2, and then, on the opposite side of the air electrode overlapping the electrolyte membrane, the catalyst layer overlaps the fuel electrode on the electrolyte membrane side at a temperature of 120 ° C, and the pressure is 120 ° C. The membrane electrode assembly (MEA) was produced by pressurization under the conditions of 10 kgf/cm2. However, the electrode area was an air electrode and the fuel electrode was simultaneously 12 cm2. Next, the membrane electrode assembly (MEA) was sandwiched by a gold thin having a plurality of openings for introducing air and vaporized methanol to form a fuel electrode conductive layer and an air electrode conductive layer. The laminated body of the membrane electrode assembly (MEA), the fuel electrode conductive layer, and the air electrode conductive layer is laminated in two frames made of a resin. However, the air electrode side of the membrane electrode assembly is bonded to one side. Between the frames, the rubber electrode side of the membrane electrode assembly and the other frame are sealed by a rubber ring. In addition, the frame system on the fuel electrode side is fixed to the liquid fuel containing chamber via a gas-liquid separation membrane via a screw, and the thickness is 0 for the gas-liquid separation membrane. On the other hand, on the frame on the air electrode side, a porous plate having a porosity of 28% is disposed to form a moisturizing plate, and for the moisturizing plate, it is arranged to form an air intake. A stainless steel plate (SUS3 04) having a thickness of 2 mm, which is an air introduction port (a diameter of 4 mm and a port number of 64), forms a surface cover layer and is fastened by screwing. In the liquid fuel storage chamber of the fuel cell formed as described above, pure methanol is injected into the environment at a temperature of 25 t and a relative humidity of 50%, and the maximum output of the output is measured from the current 値 and the voltage 値, and further, by mounting on the surface layer. The surface of the thermocouple, the maximum enthalpy measurement of the surface temperature of the fuel cell is measured, and the maximum output is 12. 2mW/cm2, the maximum temperature of the surface temperature of the fuel cell is 32. 4 t. Further, 15 ml of pure methanol was injected through the liquid fuel containing chamber of the fuel cell, and the voltage was set to 0. 3V was continuously operated, and the current density was measured, and the change in output for continuous operation time was measured. The result was -25·200836394, and the output decline rate after 60 hours was 8. 1%, however, the output reduction rate after 60 hours refers to the ratio of the output which is lower than the start of the operation after 60 hours for the output at the operation start time. The MEA was taken out from the element and cut, and the cross section was observed and embedded in the resin. The MEA embedded in the resin was honed in a plane and observed by an electron microscope. As a result, The thickness of the fuel electrode catalyst layer and the air electrode catalyst layer are measured as 10 points, and the average thickness is determined. When the porosity of the catalyst layer is calculated from the thickness, the material density, and the measured weight, the fuel electrode catalyst The layer is 68. 8%, the air catalyst layer is 6 2 · 1 %. (Example 2) For the production of the fuel cell used in Example 2, first, a carbon particle of platinum yttrium alloy particles and a 2020 (manufactured by DUPONT Co., Ltd.) were mixed by a homogenizer to prepare a slurry, and the slurry was applied thereto. The fuel electrode was formed by forming one of the carbon fiber papers (TGP-H_120 manufactured by TORAY Co., Ltd.) having a porosity of 75% in the fuel gas diffusion layer, and drying the mixture at a normal temperature to form a fuel electrode layer. Next, a PTFE (polytetrafluoroethylene) sheet is placed on the fuel electrode catalyst layer, and a thickness 〇 is disposed above it. The rubber sheet of 5 mm is compressed by pressurization of the flat plate. As a result, the thickness of the fuel electrode catalyst layer is about 2/3, and the porosity of the fuel electrode catalyst layer is determined by the coating film size and material density, and the weight is measured. The result of the calculation is 66. 4% ' However, for the pressurization of the flat plate, the thickness of the fuel electrode gas diffusion layer is unchanged. -26- 200836394 Next, a slurry was prepared by mixing graphite particles supported by platinum in a homogenizer and DE2020 (manufactured by DUPONT Co., Ltd.), and applied to a carbon fiber paper having a porosity of 75% which is an air gas diffusion layer ( One side of TGP-H-12 0) manufactured by TORAY Co., Ltd., and dried at room temperature to form an air-electrode catalyst layer to form an air electrode, and the porosity of the air-electrode catalyst layer is determined by the coating film size and The material density, as well as the weight measured, was 87. 2%. As the electrolyte membrane, a fixed electrolyte membrane Nafionll2 (manufactured by DUPONT Co., Ltd.) was used, and the electrolyte membrane was sandwiched between the air electrode and the fuel electrode, and the catalyst coating layer was placed on the electrolyte membrane side at a temperature of 120 ° C. The film electrode assembly (MEA) was produced under the conditions of a pressure of 40 kgf/cm 2 . However, the electrode area was an air electrode, and the fuel electrode was simultaneously 12 cm 2 , and the other components were the fuel of Example 1. The composition of the battery is the same. Further, the maximum enthalpy of the output, the maximum 値 of the surface temperature of the fuel cell, and the measurement method and measurement conditions of the output reduction rate after 60 hours are the same as those of the measurement method and measurement conditions of the first embodiment. As a result of the measurement, the maximum enthalpy of the output is 1 1 . 8mW/cm2, the maximum enthalpy of the surface temperature of the fuel cell is 3 1 · 5 °C, and the output drop rate after 60 hours is 9. 2%. The MEA was taken out from the element and cut, and the cross section was observed and embedded in the resin. The MEA embedded in the resin was honed in a plane and observed by an electron microscope. As a result, The thicknesses of the fuel electrode catalyst layer and the air electrode catalyst layer were measured as the degree of 10 points, -27-200836394, and the average thickness was determined, and the porosity of the catalyst layer was calculated from the thickness 'material density and the measured weight. The fuel catalyst layer is 3 8 · 8 %, and the air catalyst layer is 6 7. 4%. (Example 3) For the production of the fuel cell used in Example 3, first, carbon fiber paper (TGP-H-120 manufactured by TORAY Co., Ltd.) was compressed by a flat plate, and the compressed pores of the carbon fiber paper were compressed. The rate is calculated from the outer dimensions and the measured weight, which is 40. 3% 'The carbon fiber paper is used as a fuel gas diffusion layer, and the platinum bismuth alloy particles and DE2020 (manufactured by DUPONT Co., Ltd.) are mixed and supported by a homogenizer to prepare a slurry, and the slurry is applied to the fuel. One of the surfaces of the carbon fiber paper (TGP-H-120 manufactured by TORAY Corporation) which is subjected to compression processing of the gas diffusion layer is dried at room temperature to form a fuel electrode catalyst layer, thereby producing a fuel electrode. Next, a PTFE (polytetrafluoroethylene) sheet is disposed on the fuel electrode catalyst layer, and a thickness of 0 is disposed above the fuel PTFE layer. The 5 mm sand rubber sheet was compressed by pressurization, and as a result, the porosity of the fuel electrode layer was calculated from the film size and material density, and the weight was measured. 5% However, there is no change in the thickness of the fuel electrode diffusion layer for pressurization on its plate. Then, a slurry was prepared by mixing graphite particles and DE2020 (manufactured by DUPONT Co., Ltd.) in a homogenizer, and applied to a carbon fiber paper having a porosity of 75% which is an air gas diffusion layer (TGP manufactured by TORAY Corporation). -H-12 0) One side of the surface, and dried at room temperature to form an air electrode -28 - 200836394 catalyst layer, the air electrode is formed, and the porosity of the air electrode catalyst layer is determined by the film size and As a result of the calculation of the material density and the weight measurement, 8 8 · 0 % 〇 was used as the electrolyte membrane, and the electrolyte membrane was coated with air electrode and fuel electrode using a fixed electrolyte membrane Nafionll 2 (manufactured by DUPONT Co., Ltd.). The layer was sandwiched between the electrolyte membrane side and pressurized at a temperature of 120 ° C and a pressure of 40 kgf/cm 2 to prepare a membrane electrode assembly (MEA). However, the electrode area was an air electrode and a fuel electrode. At the same time, it is 1 2 cm 2 , and the other configuration is the same as that of the fuel cell of the first embodiment. Further, the maximum output 値, the maximum 値 of the surface temperature of the fuel cell, and the measurement method and measurement conditions of the output reduction rate after 60 hours are the same as those of the measurement method and measurement conditions of the first embodiment. As a result of the measurement, the maximum enthalpy of the output is 1 1 jmW/cm 2 , and the maximum enthalpy of the surface temperature of the fuel cell is 3 1. 2, In addition, 6 0 / 』, after the time; the output decline rate is 8. 3 %. The MEA was taken out from the element and cut, and the visible cross section was embedded in the resin, and the MEA embedded in the resin was honed in a plane to observe it by an electron microscope. As a result, The thickness of the fuel catalyst layer and the air catalyst layer is measured as 10 points, and the average thickness is determined. When the porosity of the catalyst layer is calculated from the thickness, material density and measured weight, the fuel electrode catalyst The layer is 38. 1%, the air catalyst layer is 6 9. 5 %. -29. 200836394 (Comparative Example 1) The carbon fiber paper (TGP-H-120 manufactured by TORAY Co., Ltd.) having a porosity of 75% is used for the structure of the fuel cell used in Comparative Example 1 for the fuel gas diffusion layer. The configuration of the fuel cell of the first embodiment is the same. Further, the maximum output 値, the maximum 値 of the surface temperature of the fuel cell, and the measurement method and measurement conditions of the output reduction rate after 60 hours were the same as those of the measurement method and measurement conditions of Example 1. As a result of the measurement, the maximum enthalpy of the output is 12 mW/cm 2 , and the maximum enthalpy of the surface temperature of the fuel cell is 38. At 6 °C, in addition, the output decline rate after 60 hours is 20. 5%. Further, in the fuel cell used in Comparative Example 1, the fuel consumption was fast, and the time until the fuel in the liquid fuel storage chamber was consumed was short. The MEA was taken out from the element and cut, and the cross section was observed and embedded in the resin. The MEA embedded in the resin was honed in a plane and observed by an electron microscope. As a result, The thickness of the fuel electrode catalyst layer and the air electrode catalyst layer are measured as 1 point, and the average thickness is obtained. When the porosity of the catalyst layer is calculated from the thickness, the material density, and the measured weight, the fuel is extremely touched. The media layer is 69. 2%, the air catalyst layer is 6 3 . 3 %. (Review of Measurement Results of Examples and Comparative Examples) Table 1 shows the measurement results of the above-described Examples 1 to 3 and Comparative Example 1. -30- 200836394 [Table 1] Maximum 输出 of output, maximum 値 of mW/cm2 surface temperature, output reduction rate after 60 hours of °C, % Example 1 2 32. 4 8. 1 Example 2 11. 8 31. 5 9. 2 Example 3 11. 7 31. 2 8. 3 Comparative Example 1 12 38. 6 20. 5 • From the measurement results shown in Table 1, the maximum output of the first embodiment to the third embodiment and the comparative example 1 was not extremely different, and the maximum surface temperature of the fuel cell was determined in Comparative Example 1. The temperature was somewhat high, but there was no significant difference with respect to the temperatures of Examples 1 to 3. The output reduction rate after 60 hours indicates that Comparative Example 1 is larger than Example 3, and in Comparative Example 1, the output reduction rate after 60 hours is high because it is considered to be in Comparative Example 1. In the fuel cell, part of the water that has passed through the liquid electrode side from the air electrode side passes through the liquid fuel receiving chamber, becomes water vapor, passes through the gas-liquid separation membrane, and flows into the liquid fuel storage chamber, and the methanol concentration in the liquid fuel storage chamber In the case of the fuel cell of the first to third embodiments, the fuel cell of the first to third embodiments is considered to be low in the case of the fuel cell of the first to third embodiments. The porosity of the fuel electrode diffusion layer is set to be smaller than the porosity of the air electrode diffusion layer, and/or the porosity of the fuel electrode layer is made to be smaller than that of the air catalyst layer. In the case of being small, the control of the portion of the water passing through the fuel electrode side from the air electrode side passes through the fuel gas diffusion layer, thereby suppressing the decrease in the concentration of methanol 31 - 200836394 in the liquid fuel storage chamber. Further, it is understood that superior output characteristics can be obtained for the fuel cell relating to the present invention. However, the results are not shown, but for the fuel cell of Comparative Example 1 of Examples 1 to 3 S, the surface of the fuel-electroconductive layer on the liquid fuel storage chamber side is provided with a hydrophobic polytetrafluoroethylene. The result of the measurement is the same as the measurement result of the maximum enthalpy of the surface temperature of the fuel cell and the output decrease rate after 60 hours, which is the maximum output of the above-mentioned respective examples and comparative examples. result. In addition, although an example of using a passive type DMFC is shown here, it is not limited to a passive type, and if it is a structure which uses the structure of the water generate|occur| . However, the present invention is not limited to the configuration of the above-described embodiment, and in the implementation stage, constituent elements may be embodied as modifications without departing from the scope of the invention, and suitable for the plurality of constituent elements disclosed in the above embodiment. In the combination, various inventions can be formed. For example, several constituent elements can be deleted from the entire constituent elements shown in the embodiment, and constituent elements that are spread over different embodiments can be combined as appropriate. Further, the vapor of the liquid fuel supplied to the membrane electrode assembly (MEΑ) may be completely supplied with the vapor of the liquid fuel. However, the present invention is also applicable to a case where a part of the liquid fuel is supplied in a liquid state. [Possibility of Industrial Utilization] According to the fuel cell according to the aspect of the present invention, the porosity of the fuel electrode gas diffusion layer is made smaller than that of the air gas diffusion layer to be -32»200836394. In the case of setting, and/or setting the porosity of the fuel electrode catalyst layer to be smaller than the porosity of the air electrode catalyst layer, the water generated in the air electrode can be stored in the fuel electrode. Further, the fuel gas diffusion layer is controlled to be immersed in the liquid fuel storage chamber side, whereby the fuel concentration of the fuel gas diffusion layer on the liquid fuel storage chamber side can be controlled, and the fuel electrode can be controlled. When the catalyst layer is supplied with a specific concentration of fuel, it is possible to suppress the decrease in the output of the fuel cell through the continuous operation, and the fuel cell of the type of the present invention is effectively used, for example, in a liquid fuel direct supply type fuel cell or the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing a cross section of a direct methanol fuel cell according to an embodiment of the present invention. [匮I 2] is a view schematically showing a cross section of a direct methanol fuel cell of another configuration of an embodiment of the present invention. • 3] is a schematic view showing the configuration of the fuel distribution mechanism [Main component symbol description] I · Fuel cell 10 0 : Fuel cell II : Fuel electrode catalyst layer 12 · Fuel electrode gas diffusion layer 13 : Air contact Media layer-33- 200836394 1 4 : Air electrode diffusion layer 15 : Electrolyte film 16 : Membrane electrode assembly 1 7 : Fuel electrode conductive layer 1 8 : Air electrode conductive layer 1 9 : Fuel electrode sealing material 20 : Air electrode Sealing material 2 1 : Liquid fuel containing chamber 22 : gas-liquid separation membrane 2 3, 2 5 : frame 24 : gasification fuel storage chamber 2 6 : moisture layer 27 : surface cover layer 28 : air introduction port F : liquid fuel 1 3 0 : fuel distribution mechanism 1 3 1 : flow path 1 3 2 : fuel storage portion 1 3 3 : fuel injection port 134 : fuel discharge port 1 3 5 : fuel cell distribution plate 1 3 6 : gap portion 137 : valve - 34