Durability of Polymer Electrolyte Membrane Fuel Cells Operated at Subfreezing Temperatures [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 621.312 Generation, modification, storage
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Energy Efficiency and Renewable Energy ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2016
• Mô tả vật lý: Size: p. F1317-F1329 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 255764
• Chủ đề: 1. 30 direct energy conversion; 2. 37 inorganic, organic, physical, and analytical chemistry; 3. Durability; 4. Electrolyzers; 5. Energy conversion; 6. Pem fuel cell; 7. Subfreezing operation

Tóm tắt

 The structure, composition, and interfaces of membrane electrode assemblies (MEA) and gas-diffusion layers (GDLs) have a significant effect on the performance of single-proton-exchange-membrane (PEM) fuel cells operated isothermally at subfreezing temperatures. During isothermal constant-current operation at subfreezing temperatures, water forming at the cathode initially hydrates the membrane, then forms ice in the catalyst layer and/or GDL. This ice formation results in a gradual decay in voltage. High-frequency resistance initially decreases due to an increase in membrane water content and then increases over time as the contact resistance increases. The water/ice holding capacity of a fuel cell decreases with decreasing subfreezing temperature (-10�C vs. -20�C vs. -30�C) and increasing current density (0.02 A cm<
 sup>
 -2<
 /sup>
  vs. 0.04 A cm<
 sup>
 -2<
 /sup>
 ). Ice formation monitored using in-situ high-resolution neutron radiography indicated that the ice was concentrated near the cathode catalyst layer at low operating temperatures (?-20�C) and high current densities (0.04 A cm<
 sup>
 -2<
 /sup>
 ). Significant ice formation was also observed in the GDLs at higher subfreezing temperatures (?-10�C) and lower current densities (0.02 A cm<
 sup>
 -2<
 /sup>
 ). These results are in good agreement with the long-term durability observations that show more severe degradation at lower temperatures (-20�C and -30�C).