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One of the major advantages of polybenzimidazole (PBI) based high temperature polymer electrolyte (HT-PEM) fuel cells compared to the low temperature representatives of this type of fuel cell technology is the higher tolerance against impurities like CO. Nevertheless lifetime and durability are still an issue. In this work, an improvement in degradation rates and therefore an extension of lifetime of HT-PEM fuel cells will be presented. Extended long term tests have been performed at different facilities under similar test conditions. After 3,000 h of operation, an average degradation rate of -1.7 µV/h has been achieved. One of the tests is still under operation; this MEA already reached a lifetime more than 9,000 hours with an actual degradation rate of -3 µV/h.

This communication will provide details on some of the high temperature polymer electrolyte membrane (HT-PEM) membrane-electrode-assembly (MEA) performance targets most recently achieved by Danish Power Systems. These include (i) MEA performances of >0.67 V at 0.2 A cm-2using dry H2/Air, (ii) MEA lifetime of 12000 h at 0.23 A cm-2using dry H2/Air with an average degradation rate of 9 µV h-1, and (iii) an integrated 5 kW stack/reformer system using methanol reformate as fuel. Studies using reformate have also led to promising results with an MEA performance of 0.58 V at 0.4 A cm-2with a degradation rate of 24 µV h-1using wet H2(30 mol%)/Air for 500 hours. In addition to reaching these performance benchmarks, a reduction in the standard deviation for MEA performance to <5% has been achieved through efforts aimed at improving the uniformity of the membrane and catalyst layer thicknesses.