Investigation of PEMFC Stack Operating at Elevated Temperature

Proton exchange membrane fuel cell (PEMFC) operating at elevated temperature has many advantages compared to low temperature prototypes. With the adoption of short side chain, low equivalent weight (EW) perfluorosulphonic acid (PFSA) membrane, a 100W PEMFC stack was built and evaluated at an elevated temperature of 95℃. For the purpose of studying the effect of anode relative humidity (RH) on fuel cell performance, the stack was tested with (1) 60% RH air and 70% RH H₂, (2) 60% RH air and dry H₂, respectively under different temperatures. Furthermore, the CO tolerance of the stack was investigated at low and elevated temperatures in the presence of 5ppm, 10ppm and 20ppm CO/H₂, respectively. The results demonstrated that the stack performance with dry H₂ was more than 30% inferior to that with H2 of 70% RH, and the cell consistency deteriorated under higher temperature and lower anode RH. The polarization curves of the stack employed fuel rich in CO indicated that elevating the operating temperature to 95℃ could improve the anode catalyst tolerance to CO, and the CO poisoning effect on cell polarization is slight at low current densities.