Upgrade of Electrode Coating Technology for Proton-Exchange Membrane Fuel Cells (PEMFCs) by the Dispersion Control of Nano-particles

从本研究的实验和理论工作中，得到以下结论：采用改进的Usui触变性模型，考虑了悬浮介质的非牛顿流变特性的影响，可以成功地预测悬浮液的粘度。涂层速度的变化会影响局部分散条件，表现为悬浮液粘度的降低、团簇直径的减小以及催化层结构的不同。利用Usui触变性模型预测了包覆浆料的团聚特性，即团簇的大小和团簇中所含初级颗粒的数量。通过改变浆料特性和涂层条件，可以控制pemfc电极层干燥后的凝固颗粒结构。根据所建立的浆料模型，空心空间特征长度与光泽尺寸之间具有良好的相关性。仅在化学反应控制过程占优势的情况下，涂层条件对PEMFC阴极性能有影响。在阳极侧，电池电压结果主要受阴极电催化活性的影响，这导致结果没有团聚的影响。在浆液包覆过程中，随着颗粒分散速率的增加，PEMFC的性能有提高的趋势。然而，由于本研究的涂层条件有限，没有确定最佳的涂层条件。

From the experimental and theoretical work of this study, following conclusions were obtained.1. Suspension viscosity can be successfully predicted by using modified Usui's thixotropy model, in which the effect of non-Newtonian rheological characteristics of suspension medium is taken into account.2. The alternation of coating speed affects the local dispersion condition, which is indicated by the lower viscosity of suspension, lower cluster diameter and the different structure of catalytic layer. The agglomeration characteristics of coated slurry, i.e. the size of cluster and number of primary particles contained in a cluster are predicted by using Usui's thixotropy model.3. There is a possibility to control the coagulated particle structure after drying of PEMFCs electrode layer by changing the slurry characteristics and coating condition. There is a good correlation between the hollow space characteristic length and the luster size by the present slurry model.Effect of coating condition is observed only for the case of cathode performance of PEMFC where the chemical reaction controlling process prevails. In anode side, the cell voltage results were affected mainly by the electrocatalytic activity of the cathode, which leads to the results that no effect of the agglomeration. There is a tendency to increase the PEMFC performance according to the increase of particle dispersion rate during the slurry coating process. However, the optimum coating condition is not determined because of the limited coating condition of this study.