【摘要】：發(fā)展新能源汽車是世界各國提高汽車產(chǎn)業(yè)競爭力、保障能源安全和發(fā)展低碳經(jīng)濟的重要途徑。質(zhì)子交換膜燃料電池(PEMFC)作為一種高能量密度的電化學(xué)能量轉(zhuǎn)化裝置,被視為新能源汽車技術(shù)終極解決方案之一。燃料電池汽車是燃料電池發(fā)展的重要方向。2014年日本燃料電池汽車Mirai推向市場,掀起了質(zhì)子交換膜燃料電池研究和應(yīng)用的新一輪高潮。目前,生產(chǎn)成本較高和壽命仍是制約其商業(yè)化應(yīng)用的主要因素之一。我國在車用質(zhì)子交換膜燃料電池研究方面,與國外相比,在膜電極的鉑載量及使用壽命方面存在較大差距,是急需解決的問題。本文從膜電極制備工藝著手,膜電極陽極鉑載量固定為0.05 mgcm-2,在前期工作基礎(chǔ)上獲得了低鉑載量膜電極CCM制備工藝,確定了 CCM膜電極最優(yōu)催化劑配比。當Nafion含量為1.17倍標準含量時,在氫/空氣,相對濕度0%,電池溫度50℃C條件下,總鉑載量0.2 mgcm-2的CCM膜電極(陽極鉑載量0.05 mgcm-2;陰極鉑載量0.15mgcm-2)初始最優(yōu)性能可達440mWcm-2@0.6V,886 mAcm-2時其比功率可達500.2mWcm-2。該膜電極在氫/空氣,相對濕度90%/70%,電池溫度80℃C條件下,初始最優(yōu)性能可達989 mWcm-2@0.6 V。本文在獲得較好性能的低鉑膜電極的基礎(chǔ)上,采用美國能源部推薦針對催化劑鉑老化的加速壽命測試條件,通過膜電極性能、膜電極電化學(xué)比表面積測試、膜電極表面及截面掃描電鏡二次電子圖、背散射圖、元素含量線掃描、元素mapping、EDS數(shù)據(jù)等微觀形貌及元素分布與含量分析初步研究了鉑載量和質(zhì)子交換膜厚度對膜電極加速壽命的影響。不同陰極鉑載量CCM膜電極的加速壽命試驗顯示,在電流密度為800 mAcm-2時,陰極鉑載量為0.55 mgcm-2的膜電極電壓由初始的701.4 mV降至30K循環(huán)后的629.7 mV,下降10.2%;陰極鉑載量為0.15 mgcm-2的膜電極電壓由初始的674.6 mV降至30K循環(huán)后的528.9 mV,下降21.6%;陰極鉑載量為0.05 mgcm-2的膜電極電壓由初始的549 mV降至30K循環(huán)后的318.5 mV,下降42.0%。陰極鉑載量降低,膜電極加速循環(huán)壽命降低率增大。不同質(zhì)子交換膜制備總鉑載量0.2 mgcm-2CCM膜電極性能的加速壽命因不同的質(zhì)子交換膜不同而不同。試驗顯示,在電流密度為800mAcm-2條件下,厚度為50微米的NR212膜制備膜電極經(jīng)30k循環(huán),電壓由679 mV降至620.7 mV,下降8.6%;厚度為30微米的XL膜制備膜電極經(jīng)30k循環(huán),電壓由674.6 mV降至528.9 mV,下降21.6%;厚度為20微米的HP膜制備得到膜電極經(jīng)30k循環(huán),電壓由692.7 mV降至633.4 mV,下降8.6%。具有相同結(jié)構(gòu)的復(fù)合膜,更薄的復(fù)合膜有利于提高膜電極的使用壽命。針對加速壽命測試膜電極的微觀形貌和元素分布與含量分析,我們首次觀察到鉑顆粒的分區(qū)域團聚現(xiàn)象,即鉑顆粒在催化劑層與質(zhì)子交換膜界面附近團聚明顯。這為我們下一步提高膜電極的長期使用壽命指出了研究的方向與重點。
[Abstract]:The development of new energy vehicles is an important way to improve the competitiveness of automobile industry, ensure energy security and develop low carbon economy. Proton exchange membrane fuel cell (PEMFC), as a high energy density electrochemical energy conversion device, is regarded as one of the ultimate solutions of new energy vehicle technology. Fuel cell vehicle is an important direction of fuel cell development. In 2014, Japanese fuel cell vehicle Mirai came to market, which set off a new wave of research and application of proton exchange membrane fuel cell (PEMFC). At present, high production cost and service life are still one of the main factors restricting its commercial application. Compared with foreign countries, there is a big gap in the platinum load and service life of membrane electrode in our country, which is an urgent problem to be solved in the research of vehicle proton exchange membrane fuel cell (PEMFC). In this paper, the preparation process of CCM with low platinum loading at the anode of membrane electrode was obtained on the basis of the previous work. The optimum ratio of catalyst for the preparation of CCM membrane electrode was determined. When the Nafion content is 1.17 times the standard content, under the conditions of hydrogen / air, relative humidity 0 and battery temperature 50 鈩，

本文編號：2242863