质子交换膜燃料电池是一种新型的绿色能源转化器件，可将氢气、甲醇等燃料的化学能直接转化为电能，具有高能量密度、高能量转化效率等优点。但其在对外输出电能时会出现电极电势偏离平衡电势的极化现象，尤其是大电流下气体扩散受阻及电极水淹导致的浓差极化严重阻碍了功率密度的提高。制备高气体传质能力和高排水能力的气体扩散电极，来改善大电流区的性能是质子交换膜燃料电池实际应用的关键。 本文围绕在“水/气管理”中发挥重要作用的气体扩散电极微孔层入手。采用不同孔结构和比表面积的碳材料，研究了与贵金属（Pt）催化层和非贵金属（Fe-N-C）催化层分别相匹配的气体扩散电极微孔层的制备。 针对贵金属Pt催化剂，采用聚四氟乙烯（PTFE）含量20 wt%、碳载量2.0 mg/cm2、以及刮涂法，获得了微孔层的最优制备工艺。选用不同的碳材料（Vulcan碳黑、Ketjen碳黑、乙炔黑等）制备微孔层，研究了孔结构和比表面积与微孔层传质阻抗的关系。其中，使用Vulcan碳黑制备得到的微孔层孔径适中，厚度相对较薄，具有最低的传质阻抗和最优异的电池性能。制备了乙炔黑/Vulcan碳黑构成的双层微孔层，通过孔的梯度结构进一步减少了液态水饱和度，降低了传质阻力，氢氧（空）电池最大功率密度相比Vulcan碳黑单层微孔层提高了25%（7%）。 相比贵金属催化层，非贵金属Fe-N-C催化层载量高、传质差、水淹问题更严重，针对非贵金属催化剂的微孔层匹配和优化研究还很少。论文首先研究了不同催化剂载量和微孔层载量的匹配，在Fe-N-C催化剂载量为2.3 mg/cm2、微孔层Vulcan碳黑载量为1.0 mg/cm2下，实现了相对最佳的电池性能。进一步研究了不同碳材料制备的微孔层对非贵金属催化剂电池性能的影响。与贵金属Pt催化剂不同，使用乙炔黑和Super P碳黑制备得到的微孔层相比商业和Vulcan碳黑微孔层具有更低的欧姆阻抗和传质阻抗，氢氧（空）条件电池性能（最大功率密度）均提高20-30%。 论文研究为燃料电池气体扩散电极微孔层碳材料的合理选择提供了有益的探索和例证。
The proton exchange membrane fuel cell is a green energy device that can directly convert the chemical energy of fuels such as hydrogen and methanol into electrical energy. It has the advantages of high energy density and high energy conversion efficiency. However, the polarization of the electrode potential deviates from the equilibrium potential when outputting electric energy, especially the concentration polarization caused by the hindered gas diffusion under high current and the electrode flooding seriously hinders the increase of power density. The key to the practical application of proton exchange membrane fuel cells is to prepare gas diffusion electrodes with high gas mass transfer capacity and high drainage capacity to improve the performance in the high current region. This article focuses on the gas diffusion electrode micro-porous layer that plays an important role in "water/gas management". By using carbon materials with different pore structures and specific surface areas, the preparation of gas diffusion electrode microporous layers that match the noble metal (Pt) catalytic layer and the non-precious metal (Fe-N-C) catalytic layer were studied. For the precious metal Pt catalyst, the optimal preparation process of the microporous layer was obtained by adopting the polytetrafluoroethylene (PTFE) content of 20 wt%, the carbon loading of 2.0 mg/cm2, and the blade-coating method. Different carbon materials (Vulcan carbon black, Ketjen carbon black, acetylene black, etc.) were used to prepare the micro-porous layer, and the relationship between the pore structure and specific surface area and the mass transfer resistance of the microporous layer was studied. Among them, the microporous layer prepared by using Vulcan carbon black has a moderate pore size, a relatively thin thickness, the lowest mass transfer resistance, and the most excellent cell performance. A double-layer microporous layer composed of acetylene black/Vulcan carbon black was prepared. The gradient pore structure further reduces the saturation of liquid water and improves the mass transfer resistance. Compared with the Vulcan carbon black single micro-porous layer, the maximum power density of double micro-porous layer in hydrogen-oxygen (air) fuel cell is increased by 25% (7%). Compared with the noble metal catalyst layer, the non-noble metal Fe-N-C catalyst layer has high loading, poor mass transfer, and more serious water flooding problems. There are few studies on the matching and optimization of the microporous layer of non-noble metal catalysts. The thesis first studied the matching of different catalyst loadings and microporous layer loadings. The relatively best cell performance was achieved when the Fe-N-C catalyst loading was 2.3 mg/cm2 and the microporous layer Vulcan carbon black loading was 1.0 mg/cm2. The effect of micro-porous layers made of different carbon materials on the cell performance of non-precious metal catalyst was further studied. Unlike the precious metal Pt catalyst, the micro-porous layer prepared by using acetylene black and Super P carbon black has lower ohmic resistance and mass transfer resistance than commercial and Vulcan carbon black microporous layers. The cell performance (maximum power density) under hydrogen and oxygen and hydrogen air conditions was increased by 20-30%. The research in the thesis provides a useful exploration and illustration for the reasonable selection of carbon materials in the microporous layer of the fuel cell gas diffusion electrode.
