Performance and Oscillation Behavior of PBI-Phosphoric Acid based Higher-Temperature Vapor Feed Direct Methanol Fuel Cells

Dong, Yan

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Performance and Oscillation Behavior of PBI-Phosphoric Acid based Higher-Temperature Vapor Feed Direct Methanol Fuel Cells

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Operation of a Direct Methanol Fuel Cell (DMFC) at high temperature with vapor feed can avoid many of the issues of conventional low temperatures DMFC, such as crossover, low efficiency and high catalyst loading. Here we investigate the behavior of a PBI-phosphoric acid membrane based DMFC. This project has two goals. The first goal is to investigate the effect of temperature and methanol concentration on the performance of Direct Methanol Fuel Cell (DMFC). The second goal is to investigate the effect of temperature and methanol on its oscillatory behavior under constant current or constant voltage operation. In this project, we use a commercial polybenzimidazole (PBI)-phosphoric acid based membrane electrode assembly (MEA), namely, Celtec-P 1100 from BASF. The Celtec-P 1100 MEA is actually designed for high temperature operation with referenced hydrogen. This kind of MEA operates at temperatures between 140℃ to 180℃, tolerating high concentrations of carbon monoxide and running independently of humidification. This study uses different vaporized concentration methanol instead of hydrogen at the anode and oxygen at the cathode. We tested in different conditions, the concentration of methanol from 1M to 10M and the operating temperature from 160℃ to 180℃. Results show that the performance of fuel cell increases with temperature up to 180℃ and the effect of methanol concentration is small. Further, oscillatory behavior is observed and reported for the first time. The oscillation is not significantly affected by the temperature and methanol concentration, current density or voltage. However, the oscillation is in special region in different condition.

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