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

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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.