【作者】 张宇；

【导师】 杜新；

【作者基本信息】 长春理工大学 ， 机械工程， 2019， 硕士

【摘要】 PEMFC(Proton Exchange Membrane Fuel Cell)理论上只排放水,是没有污染物的清洁能源,对于以后能源发展也是一种趋势。标准状态下,燃料电池理论电势是1.23V,但在实际使用中的开路电压只有0.95V~1.05V,其主要原因是氢气渗透产生的过电势降低了开路电压。在以往研究中,认为氢气渗透也符合法拉第定律,目前还没有具体文献和实验证明这一观点。本文避免这一假设,引进内电流的概念,重新推导出内电流与过电势的关系,得出内电流的产生会影响电池开路电压的结论。本文主要研究质子交换膜特性和质子交换膜内缺陷对电池的影响,分别从质子交换膜的厚度、质子交换膜内有孔、催化层有水膜和催化剂Pt载量大小等几个方面来分析电池性能。质子交换膜厚度对电池的影响:当膜厚度减小时,氢气渗透通量增加,在内电流相同的条件下,需要增大过电势来平衡氧气浓度的减小;在催化方面,催化层有水膜和催化剂Pt负载担量会影响氢气转换成氢离子的数量,从而影响氢气渗透通量,得出Pt负载担量越大对电池越好,催化层有水膜比没有水膜好的结论。同时也研究了在膜内有孔情况下,不同孔深度和孔密度对电池的影响:孔深度在110μm范围内对电池影响相对较小,而且随着孔深度增加,过电势增加越明显;分析孔密度在10以内,对电池影响相对小;对于L型裂纹,竖直方向影响要大于水平方向;并且电流密度在0~97 mA/cm~2范围内,氢气渗透产生的过电势对电池的开路电压影响大;随着电流密度的增加其影响开路电压的主要因素是欧姆损失;同时研究质子交换膜在有孔情况下,电池的电阻增加,电导率减小;电池的性能也会随之下降。更多还原

【Abstract】 PEMFC(Proton Exchange Membrane Fuel Cell)theoretically only emits water and is a clean energy without pollutants,which is also a trend for future energy development.In the standard state,the theoretical potential of the fuel cell is 1.23v,but the actual open-circuit voltage is only 0.95v~1.05v,mainly because the over-potential generated by hydrogen penetration reduces the open-circuit voltage.In previous studies,it was believed that hydrogen permeation also conforms to Faraday’s law.This paper avoids this hypothesis,introduces the concept of internal current,deduces the relationship between internal current and over-potential again,and draws the conclusion that the generation of internal current will affect the open circuit voltage of the battery.In this paper,the characteristics of the proton exchange membrane and the effect of defects in the proton exchange membrane on the battery were studied,and the battery performance was analyzed from the following aspects:thickness of the proton exchange membrane,pores in the proton exchange membrane,water film in the catalytic layer and the size of catalyst Pt load.The influence of proton exchange membrane thickness on the battery:when the membrane thickness decreases,the permeation flux of hydrogen increases.Under the same internal current,the over-potential needs to increase to balance the decrease of oxygen concentration.In terms of catalysis,the presence of water film and catalyst Pt load load in the catalytic layer will affect the number of hydrogen ions converted to hydrogen,thus affecting the permeation flux of hydrogen.It is concluded that the larger the Pt load load is,the better the battery is,and the presence of water film in the catalytic layer is better than the absence of water film.At the same time,the effects of different hole depths and hole densities on the battery were also studied under the condition that there were holes in the membrane.The hole density is less than 10,which has relatively little influence on the battery.For the l-type crack,the vertical influence is greater than the horizontal one.Moreover,the current density is within the range of 0~97 mA/cm~2,and the over-potential generated by hydrogen penetration has a great influence on the open circuit voltage of the battery.With the increase of current density,ohmic loss is the main factor that affects the open-circuit voltage.At the same time,when the proton exchange membrane has holes,the resistance of the battery increases and the conductivity decreases.The performance of the battery will also decline.更多还原