来源：直接甲醇燃料电池膜电极制备及阴极结构研究 发布时间：2010年7月23日
膜电极(MEA)是直接甲醇燃料电池(DMFC)的核心部件。目前，MEA的性能是阻碍DMFC商业化的瓶颈之一，因此制备高性能MEA对DMFC的研究开发具有重要意义。 本论文首先建立了一种DMFC电极制备方法-改进的转压法。比较了转压法和刷涂法制备的电极形貌、电催化剂粒径、电化学活性表面积、MEA内阻及电池性能；研究了转压法制备过程中Nafion聚合物向阴极催化层表面迁移的现象，并提出了可能的机理；考察了阴极催化层表面Nafion聚合物含量对电池性能的影响。 通过双催化层结构和碳粉引入分别优化了阴极的孔结构和憎水性。采用非担载型Pt黑电催化剂和担载型20wt．％(或40wt．％)Pt／C电催化剂制备了双催化层阴极，利用两种电催化剂本体性质的不同，形成了双催化层阴极内憎水性、孔结构和催化剂浓度的梯度分布，有利于氧气扩散和水的排出，在90℃，2atm氧气和空气条件下，最高功率密度分别达到254.8mW／cm2和176mW／cm2。研究了阴极催化层中加入碳粉对电池性能的影响，结果表明加入Ketjen BlackEC-300J碳粉的阴极性能最优，在电池温度为60℃，空气自呼吸条件下，Pt黑和Pt黑+10wt．％KB阴极的电池最高功率密度分别为19.0和48.9mW／cm2。 定量分析了甲醇渗透和水的扩散对空气自呼吸式DMFC电池性能的影响。研究了影响空气自呼吸式DMFC寿命的主要因素，并探索了有效的解决途径。 初步探索了Black Pearls 2000碳粉为载体的阴极Pt／C电催化剂在DMFC中的应用。结果表明，在不需要任何憎水剂和后处理的情况下，36wt．％Pt／BP2000电催化剂提高了在高电流密度下的DMFC性能。【Abstract】 Membrane & electrode assembly (MEA) is the core component of direct methanol fuel cell (DMFC). Up to now, the performance of MEA is still one of the factors which inhibit the commercialization of DMFC, so fabrication of high-performance MEAs is very important for the research and development of DMFC.In this dissertation, the modified decal method was developed to prepare DMFC electrodes. The electrode morphology, particle size of the electrocatalyst, electrochemical active area, resistance and performance of MEAs prepared by the decal and brush methods were compared. The enrichment of ionomer close to the surface of the cathode catalyst layer was studied and possible mechanisms were also proposed. The effect of ionomer content close to the surface of the cathode catalyst layer was explored.The pore structure and hydrophobic property of the cathode were optimized by double-layered structure and carbon black additive, respectively. A novel double-layered cathode catalyst layer for DMFC was prepared, which consisted of Pt black inner catalyst layer and 20wt.% Pt/C (or 40wt.% Pt/C) outer catalyst layer. Due to the intrinsic properties of the two electrocatalysts, hydrophobic property, porosity and catalyst gradient were formed in the cathode. The double-layered structure was beneficial for oxygen diffusion and water removal, the maximum power densities of 254.8 and 176mW/cm2 were achieved under 2atm oxygen and air at 90°C, respectively. The effect of