Effect of Operation Strategies on Phosphoric Acid Loss in HT-PEM Fuel Cells

Abstract

One of the most important degradation mechanisms, which cause a reduction of lifetime and performance of high temperature polymer electrolyte membrane (HT-PEM) fuel cells, is phosphoric acid loss. This paper presents the effect of different operation strategies on performance and acid loss of HT-PEM fuel cells on single cell level. The applied operation strategies are fuel switching, Start/Stop-cycling and long term testing under constant load with different gas compositions. The membrane electrode assemblies (MEA) are investigated in-situ via electrochemical characterization and ex-situ by post-mortem micro-tomography imaging and analysis. These results are compared with the ante-mortem counterpart. The anode humidification causes a higher amount of product water but no increase of phosphoric acid loss. In addition the wet fuel results in unclosing of the pores of both gas diffusion layers.