Corrosion of carbon supports at cathode during hydrogen/air replacement at anode studied by visualization of oxygen partial pressures in a PEFC—Start-up/shut-down simulation

A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

“…Nevertheless, to prevent performance degradation during the shutoff process, the air supply should be closed prior to the hydrogen supply to prevent air permeation to the anode, which would otherwise result in a hydrogen/air interface at the anode during the shutdown process. Inukai et al [41] simulated startup/shutdown cycles by exchanging hydrogen and air at the anode. During this gas exchange, the distribution of oxygen partial pressures at the anode was visualized using a real-time/space visualization system, which clearly showed the location of H 2 -rich and O 2 -rich areas along the gas-flow channel from the inlet to the outlet.…”

“…They observed several holes at the catalyst layer, with no Reprinted from Ref. [41] with permission.…”

Influence of the microporous layer on carbon corrosion in the catalyst layer of a polymer electrolyte membrane fuel cell

“…Lamibrac et al [27] reported higher CL degradation in the outlet region after repeated cell startups, by measuring the internal currents and EIS (electrochemical impedance spectroscopy). A visualization technique was employed by Ishigami et al [32] to measure the distribution of oxygen partial pressure in the flow field and record the progression of H 2 /air front during SU/SD operation. The inlet and especially outlet region were identified as critical regions that suffered higher levels of performance degradation due to CL damage during SU/SD cycling.…”

Quantitative analysis of carbon corrosion during fuel cell start-up and shut-down by anode purging

“…Since this process would be largely independent of the reactant gas composition in case of pure plug flow, the observed effect of hydrogen concentration suggests that the exchange of the anode gas is strongly affected by diffusion processes in the GDL and the catalyst layer of the negative electrode. This strong influence of diffusion phenomena is supported by the fact that the effective duration of the gas replacement process was found to be significantly higher than the calculated residence time of the gas front [30].…”

“…This behavior might partly be explained by the discrepancy between the theoretical gas front residence time and the effective duration of the gas exchange process. Ishigami et al have shown that the two values can differ by a factor of seven [30]. However, even if this difference is considered, the pseudo-capacitive effect would be expected to cause marked deviations from the linear correlation between carbon corrosion rate and front residence time.…”