Preparation And Properties Research Of Polyphenylene Sulfide/Graphite Bipolar Plate Material Reinforced By Milled Carbon Fiber

Polymer electrolyte membrane fuel cell (PEMFC) is recognized as a new alternative to the present power sources. The bipolar plate is an important part in PEMFC, which accounts for about 60% of PEMFC stack. While the high cost of PEMFC is a key obstacle to its wide application. Therefore, searching materials and manufacturing methods for high performance and low cost bipolar plate has become a very important project. With the above background, new materials and manufacturing methods for bipolar plates are explored in this study.According to property demand on carbon filler/polymer bipolar plate by USA DOE, the bending strength and electrical conductivity were considered as a major factor during the research. Some parameters such as PPS resin content, molding temperature and holding time were optimized so as to get the best conducting property and mechanical property. The influential factors and mechanisms mentioned above on the composite mechanical property and electrical conductivity were analyzed theoretically. The researching results show that: (1) compression after holding and cooling in the air should be chosen when preparing PPS/G composite, by which the bending strength of the composite can be improved distinctly; (2) the type of the graphite powder must be determined because different type of the graphite powder will have effect on the properties of the composite; (3) by optimization, the properties of the composite can meet the DOE standard and the results can be better than the researching results at home and abroad.The milled carbon fiber was used to reinforce the PPS/G bipolar plate composite in order to improve the properties of the composite. The research was done on the influences of carbon fiber surface treatment and content on the properties of milled carbon fiber reinforced PPS/G composite. The results show that: (1) the bending strength and electrical conductivity of the composite reinforced by gas-phase oxidation treated milled carbon fibers are optimum when the content of carbon fibers is 5%. The bending strength of the composite rises from 52.1MPa to 57.3MPa, while the conductivity descends from 133.9S/cm to 111.9S/cm; (2) although the bending strength of the composite which is reinforced by gas and liquid phase oxidation treated carbon fibers can rise in wide-range, the electrical conductivity of the composite was deteriorated.In addition, the corrosion phenomenon of the PPS/G bipolar plate in the simulation environment of fuel cell was studied in detail firstly and then the mechanism analysis of the properties descent of the composite was also given. The results show that the bipolar plate composite possesses a favorable corrosion resistant property and both the electrical conductivity and bending strength reduction ranges of the composite are lower than that of the same kind resin/graphite bipolar plate composite.