Long‐term testing of a high temperature polymer electrolyte membrane fuel cell: The effect of reactant gases

Abstract

The investigations have been conducted with different oxidants and fuels with the aim of determining the state-of-the-art of commercially available high temperature polymer electrolyte fuel cells based on polybenzimidazole for its application in combined heat and power generation systems. The fuel cell test performed with synthetic reformate (263 lV/h) showed an increase of anode charge and mass transfer resistances. This behavior has suggested that CO may be generated from the CO 2 included in the synthetic reformate via reverse water gas shift reaction. The fuel cell test performed with pure O 2 developed the highest degradation rates (270 lV/h) due to fast oxidative degradation of membrane electrode assembly materials such as cathode catalyst and membrane. Fuel cell operation with H 2 /air exhibited the lowest degradation rates (257 lV/h) and it requires longer investigating times to identify the different degradation mechanisms. Moreover, fuel cell tests performed with air suggested longer break-in procedures to complete catalyst activation and redistribution of electrolyte.

Long‐term Operation of High Temperature Polymer Electrolyte Membrane Fuel Cells with Fuel Composition Switching and Oxygen Enrichment

“…Thus, the MEA operated with Cycle 1 revealed a starting voltage value of 634 mV at 0.3 A cm −2 (Figure ), while the MEA operated with Cycle 2 exhibited an initial voltage of 615 mV at the same current density (Figure ). In previous publications where tests were conducted under no fuel switching conditions , the MEA operated with pure hydrogen showed similar voltage output (604 mV) at BoL and 0.3 A cm −2 and behavior over time than the MEA operated with 22% CO 2 and H 2 (600 mV), but this second one underwent slightly higher degradation than the one operated with pure H 2 as already discussed above.…”

“…Thus, fuel cell operation between pure hydrogen and synthetic dry reformate has apparently not induced extra degradation in the fuel cell. Previous investigations from the research group , where 1,000 h tests were evaluated using G55 Dapozol ® MEAs, showed that the fuel cell operated with pure H 2 and air developed a degradation rate of –57 μV h −1 and the one performed with synthetic reformate and air showed a slightly higher degradation rate (–63 μV h −1 ). Table summarizes all degradation rates arisen in the present study.…”

“…It also allows the conclusion that H 2 dilution with CO 2 seems to have only little effect on the fuel cell degradation and performance. This assumption is in accordance with literature as well as from previous investigations of the research group .…”

High‐Stability Electrodes for High‐Temperature Proton Exchange Membrane Fuel Cells by Using Advanced Nanocarbonaceous Materials

“…The spectra data obtained at j = 0.3 A cm À2 was fitted to an equivalent electrical circuit model R (RQ) (RQ). [26][27][28][29] From this fitting, ohmic resistance (R W ), charge transfer resistance (R CT ) and for the case of the impedances performed with air, the mass transfer resistances (R MT ) were obtained. [26][27][28] Their values are shown in Table 1.…”

“…every 200 hours approx.). [29,[37][38][39] To the best of our knowledge, in the literature there are not described any single cell operation with PBI-based HT-PEMFC systems, where these new micro porous layer (MPL) and catalyst supports are used at the same time in the cathode. Just a preliminary test was performed by our research group testing the CNSs based MPL in a lifetest, but with a lesser aggressive operational conditions.…”