PEMFC anode durability : innovative characterization methods and further insights on OER based reversal tolerance

Abstract

Durability is a major lever for commercial success of proton exchange membrane fuel cells (PEMFCs). The introduction of OER catalyst to the PEMFC anode has been established as a material based mitigation strategy for reversal events caused by gross fuel (i.e. H2) starvation. We investigated the degradation of two different OER based reversal tolerant anodes during short-term recurring reversal operation to mimic field occurrence of reversal events realistically. PEMFC failure during normal operation can be observed whereas OER activity during reversal operation is unaffected. This result is in contrast to findings for commonly applied prolonged reversal accelerated stress tests (ASTs) and indicates an OER catalyst recovery effect for short and recurring reversal events. Combining the developed AST with cyclic voltammetry, electrochemical impedance spectroscopy and hydrogen pump, tests failures during normal operation is mainly assigned to hydrogen oxidation mass transfer increase indicating carbon corrosion and structural change within the anode catalyst layer. Consequently, the developed combination of AST and further characterization methods enables in situ distinction between catalyst and structural degradation, highlighting to be a good basis to investigate future aspects regarding anode degradation caused by cell reversal.