COMPOSITE MEMBRANES FOR HIGH TEMPERATURE OPERATION OF PROTON-EXCHANGE MEMBRANE FUELS CELLS

摘要

Development of hydrogen/oxygen proton-exchange membrane fuel cells (PEMFCs) operating above 120℃ could help to alleviate some of the technical issues associated with adapting present PEMFCs technology to applications such as transportation and small-scale power generation. At typical operating temperatures of around 80℃. problems with CO poisoning of the platinum anode catalyst, and thermal and water management make the development of a simple and reliable fuel cell system more difficult. Use of hydrocarbon or alcohol fuels such as natural gas, gasoline, or methanol are more economically and technically viable in the near-term than using hydrogen. As a result, the hydrogen-rich gas will contain a significant concentration of CO and methods of reducing the impacts of this CO (either by oxidation or increasing PEMFC tolerance) become important. Increasing the temperature of fuel cell operation reduces the adsorption of CO onto the platinum electrocatalyst. In addition, temperature of the fuel cell stack is greatly enhanced at high temperatures through more efficient heat exchange. At high temperatures, water is produced as a vapor and cathode-flooding problems can be alleviated as well as producing a more valuable waste heat that could be used in a secondary application.