Yanghua Tang

Temperature Dependent Performance and In Situ AC Impedance of High-Temperature PEM Fuel Cells Using the Nafion-112 Membrane

In this paper, temperature dependent performance of a Nafion 112-based proton exchange membrane (PEM) fuel cell was investigated at different temperatures, 30 psig back pressure, and 100% relative humidity (RH). High cell performance of ca. 0.637 V at 1.0 A/cm 2 was obtained at 120°C. Cell voltage decreased when the temperature increased within the range of 80-20°C. An in situ ac impedance spectroscopy method under load was developed to diagnose the performance reduction. A semi-empirical treatment was initiated to obtain expressions for extinguishing the individual performance drops caused by reaction kinetics (charge-transfer resistance), membrane resistance, and mass-transfer limitation, respectively.

Single PEMFC Design and Validation for High-Temperature MEA Testing and Diagnosis up to 300 ° C

A single proton exchange membrane fuel cell (PEMFC) and associated hardware were designed for high-temperature membrane electrode assembly (MEA) testing and diagnosis in the range of 160-300°C. The fuel cell heating strategy and its design considerations with respect to heat balance are also discussed in this paper. The fuel cell performance of PEMEAS H 3 PO 4 -doped polybenzimidazole (PBI)-based MEAs and the corresponding ac impedance diagnosis demonstrated that this single cell and its associated hardware designs are feasible for high-temperature MEA testing. The apparent exchange current densities for the cathodic oxygen reduction reaction as a function of temperature were obtained through ac impedance measurement. Rapid performance degradation was observed at extreme temperatures, such as 300°C, suggesting an accelerated fuel cell testing method. AC impedance results showed that the activity loss of the catalyst/catalyst layer was responsible for this degradation.