Performance and durability of high temperature proton exchange membrane fuel cells with silicon carbide filled polybenzimidazole composite membranes

Abstract

High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are used for stationary to mobile applications and show increased tolerances to fuel impurities like CO compared to their low temperature counterpart. However, conventional HT-PEMFC membranes, based on polybenzimidazole (PBI), suffer from creeping during long-term operation and thus a significant increase in surface resistance. In this study, inorganic fillers in terms of silicon carbide (SiC) are incorporated into the standard PBI-based Celtec®-P membrane by a well-established large-scale polyphosphoric acid process. Operations over 1000 h of load cycling between 0.6 and 1.0 A cm−2 of SiC and for conventional HT-PEMFCs reveal differences in long-term durability. The ohmic resistance of the SiC-based single cell is 1/3 lower, while the membrane has a higher thickness retention. Cell performances are improved with lower degradation rates (<65 μV h−1 for both SiC and >100 μV h−1 for both conventional HT-PEMFCs) after 1000 h. However, SiC particle mobility and increased hydrogen permeability are observed after testing.