Studies On Direct Dimethyl Ether Fuel Cells

Direct Dimethyl Ether Fuel Cells (DDFCs) is one type of direct fuel PEMFC with characteristics of high energy density, no poison and rich in resources. In this thesis, the mechanism for electrocatalytic oxidation of DME was studied by the methods of electrochemistry. The performance of fuel cells was improved after optimizing the structure of MEAs and operating conditions of cells.The electro-oxidation of DME was studied by using cyclic voltammograms, stripping voltammograms and chronoamperograms. The effects of temperature on electro-oxidation of DME were also investigated. From result obtained, the dual-path mechanisms for electro-oxidation of DME at Pt and Pt-Ru were presented, which could explain the process for electro-oxidation of DME. The result also showed that activation of catalysts increased obviously with increasing temperature and activation of Pt-Ru was better than that of Pt on electro-oxidation of DME.According to the properties of DME, a setup for DDFC has been fabricated. The effects of several elements such as structure of MEAs, hot-pressing conditions and sealed materials on performance of fuel cells were investigated by methods of V-I polarization and AC impedance spectroscopy, and the best chooses were made with the result. Four kinds of MEAs in different preparation methods were compared in their surface microtopography by SEM and performance. MEAs made in"decal method"showed the best performance and homogeneous porous surface microtopography. Methanol method of MEAs conditioning was utilized to maximize the cell performance, and the result showed MEAs could obtain the best performance in short time. Effects of feed-in methods, Pt-Ru loading, oxygen pressure and operating-temperature on performance of DDFC were also investigated. The results demonstrated that performance was enhanced with increase in relevant parameters.