低铂膜电极加速寿命及相关影响因素研究
发布时间：2018-09-14 13:39
【摘要】：发展新能源汽车是世界各国提高汽车产业竞争力、保障能源安全和发展低碳经济的重要途径。质子交换膜燃料电池(PEMFC)作为一种高能量密度的电化学能量转化装置,被视为新能源汽车技术终极解决方案之一。燃料电池汽车是燃料电池发展的重要方向。2014年日本燃料电池汽车Mirai推向市场,掀起了质子交换膜燃料电池研究和应用的新一轮高潮。目前,生产成本较高和寿命仍是制约其商业化应用的主要因素之一。我国在车用质子交换膜燃料电池研究方面,与国外相比,在膜电极的铂载量及使用寿命方面存在较大差距,是急需解决的问题。本文从膜电极制备工艺着手,膜电极阳极铂载量固定为0.05 mgcm-2,在前期工作基础上获得了低铂载量膜电极CCM制备工艺,确定了 CCM膜电极最优催化剂配比。当Nafion含量为1.17倍标准含量时,在氢/空气,相对湿度0%,电池温度50℃C条件下,总铂载量0.2 mgcm-2的CCM膜电极(阳极铂载量0.05 mgcm-2;阴极铂载量0.15mgcm-2)初始最优性能可达440mWcm-2@0.6V,886 mAcm-2时其比功率可达500.2mWcm-2。该膜电极在氢/空气,相对湿度90%/70%,电池温度80℃C条件下,初始最优性能可达989 mWcm-2@0.6 V。本文在获得较好性能的低铂膜电极的基础上,采用美国能源部推荐针对催化剂铂老化的加速寿命测试条件,通过膜电极性能、膜电极电化学比表面积测试、膜电极表面及截面扫描电镜二次电子图、背散射图、元素含量线扫描、元素mapping、EDS数据等微观形貌及元素分布与含量分析初步研究了铂载量和质子交换膜厚度对膜电极加速寿命的影响。不同阴极铂载量CCM膜电极的加速寿命试验显示,在电流密度为800 mAcm-2时,阴极铂载量为0.55 mgcm-2的膜电极电压由初始的701.4 mV降至30K循环后的629.7 mV,下降10.2%;阴极铂载量为0.15 mgcm-2的膜电极电压由初始的674.6 mV降至30K循环后的528.9 mV,下降21.6%;阴极铂载量为0.05 mgcm-2的膜电极电压由初始的549 mV降至30K循环后的318.5 mV,下降42.0%。阴极铂载量降低,膜电极加速循环寿命降低率增大。不同质子交换膜制备总铂载量0.2 mgcm-2CCM膜电极性能的加速寿命因不同的质子交换膜不同而不同。试验显示,在电流密度为800mAcm-2条件下,厚度为50微米的NR212膜制备膜电极经30k循环,电压由679 mV降至620.7 mV,下降8.6%;厚度为30微米的XL膜制备膜电极经30k循环,电压由674.6 mV降至528.9 mV,下降21.6%;厚度为20微米的HP膜制备得到膜电极经30k循环,电压由692.7 mV降至633.4 mV,下降8.6%。具有相同结构的复合膜,更薄的复合膜有利于提高膜电极的使用寿命。针对加速寿命测试膜电极的微观形貌和元素分布与含量分析,我们首次观察到铂颗粒的分区域团聚现象,即铂颗粒在催化剂层与质子交换膜界面附近团聚明显。这为我们下一步提高膜电极的长期使用寿命指出了研究的方向与重点。
[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，
本文编号：2242863
[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，
本文编号：2242863
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