【作者】 李颖；

【导师】 王建川；

【作者基本信息】 重庆大学 ， 化学， 2022， 硕士

【摘要】 燃料电池作为一种高效清洁,有望转变传统能源结构的新能源装置,将成为缓解能源危机、减小环境污染的中坚力量,但燃料电池商业化始终面临着成本的制约。降低燃料电池成本需要大幅降低贵金属催化剂Pt的用量,而在传统催化层（CL）中,当催化剂Pt的载量大幅降低后,阴极反应气体氧气穿透离聚物层的局域传质阻力急剧增大,导致电池性能下降。为降低氧气局域传质阻力,针对催化层的设计与调控十分必要。本论文立足于构筑完全不同于传统的催化层结构,将离聚物的传统“均匀覆盖”形态,变革性的转变颗粒状或纤维状形态,不覆盖Pt催化剂,氧气无需穿透离聚物薄层而直接到达催化剂表面,构建大量的“固-液-气”三相催化反应界面,极大降低局域传质阻力,提高了燃料电池性能。主要工作如下:1.纳米纤维形态离聚物对催化层局域传质阻力及燃料电池性能的影响研究。采用静电纺丝技术制备纳米纤维状离聚物Nafion NF,替代传统的Nafion溶液制备膜电极（MEA）,并对其催化层结构、气体传质阻力和电池性能进行了系统研究。结果显示:阴阳极负载均为0.05 mg _Pt cm^-2、I/C=0.5的条件下,MEA-NNF-50的峰值功率密度为1097 m W cm^-2,相对于传统Nafion溶液离聚物的MEA-Nafion,峰值功率密度提升97%。具体可归因于:1)纤维状离聚物不覆盖Pt催化剂,增加了Pt活性位点的暴露,提高了催化剂的利用率;2)氧气无需穿透离聚物薄层而直接到达暴露的催化剂表面,从而极大的降低氧气局域传质阻力。2.多孔颗粒形态离聚物对燃料电池性能的影响研究。以联苯二氯苄为单体出发,合成了自聚微孔有机聚合物（颗粒状离聚物P-BP-BPTM_X）,构建新型颗粒状离聚物/催化剂界面,并对其催化层结构和电池性能进行了研究。结果显示:当IEC=2.07 mmol g^-1时,MEA-P-BP-BPTM_0.5达到最高的峰值功率密度1072 m W cm^-2,相较于溶液离聚物（均匀覆盖）所制备的MEA,性能提升68%。这归因于颗粒状离聚物P-BP-BPTM_X的加入,有效提升了催化层的孔隙和气体传输效率。更多还原

【Abstract】 As an efficient and clean new energy device that is expected to change the traditional energy system,fuel cells are a promising route to alleviate the energy crisis and reduce the environmental pollution,but the commercialization of fuel cells has always been restricted by the cost.Reducing the cost of fuel cells requires a significant reduction in the loading of noble metal catalyst Pt,while in the traditional catalytic layer（CL）,when the Pt loading is greatly reduced,the local mass transfer resistance of the oxygen penetrating the ionomer layer sharply increases,resulting in decreased battery performance.In order to reduce the oxygen local transport resistance,it is necessary to design high-efficient catalytic layer.This thesis aims on the construction of a catalyst layer structure that is completely different from the traditional one,adopting a novel ionomer form of particular or fibrous without covering the Pt catalyst,rather than traditional"uniform coverage"on Pt catalyst,thus the oxygen does not need to penetrate the thin ionomer film coated on Pt catalyst.In consequence,a large number of"solid-liquid-gas"three-phase catalytic reaction interfaces are constructed,which greatly reduces the local mass transfer resistance and improves the performance of the fuel cell.The main work are as follows:1.Study of the effect of nanofibrous ionomers on the local mass transfer resistance of the catalytic layer and the performance of fuel cells.Nanofibrous ionomer（Nafion NF）was prepared by electrospinning to replace the traditional Nafion solution to prepare membrane electrode（MEA）,and its catalytic layer structure,gas mass transfer resistance and battery performance were systematically studied.The results showed that the peak power density of MEA-NNF-50 is 1097 m W cm^-2 with Pt loading of 0.05 mgpt cm^-2 and I/C=0.5（both cathode and anode）,which is 97%higher than that of MEA-NNF-50 with traditional Nafion solution ionomer.Specifically,it can be attributed to 1)the fibrous ionomer does not cover the Pt catalyst,which increases the exposure of Pt active sites and improves the utilization of the catalyst;2)Oxygen does not need to penetrate the ionomer thin layer and directly reaches the exposed surface of the catalyst,which greatly reduce the local mass transfer resistance of oxygen.2.Study of the effect of porous particle morphology ionomer on fuel cell performance.Using biphenyl dichlorobenzyl as the monomer,a self-polymerizing microporous organic polymer（particulate ionomer P-BP-BPTM_X）was synthesized,a new particulate ionomer/catalyst interface and catalytic layer was constructed.The results showed that when IEC=2.07 mmol g^-1,MEA-P-BP-BPTM_0.5 reached the highest peak power density of 1072 m W cm^-2,which is 68%higher than that of the MEA prepared with ionomer solution（uniform coverage）.This is ascribed to the addition of the particulate ionomer P-BP-BPTMX improving the porosity and gas transport efficiency of the catalytic layer.更多还原