Local impact of load cycling on degradation in polymer electrolyte fuel cells

Use of X-ray computed tomography for understanding localised, along-the-channel degradation of polymer electrolyte fuel cells

“…Using a specially designed segmented cathode, the localised electrochemical performance could be analysed and an inhomogeneous performance distribution was observed across the MEA from inlet to outlet over the course of degradation [28]. Other work by Garcia-Sanchez et al has used current mapping to show the localised degradation of PEFCs, with SEM used for ex-situ visualisation of platinum in the membrane [29]. Such non-uniform degradation has been reported by a number of practitioners, but, until now, only in 2D, ex-situ SEM studies [11,[28][29][30] or by using nano-scale techniques, like X-ray absorption fine structure (XAFS) or scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) [31].…”

“…Other work by Garcia-Sanchez et al has used current mapping to show the localised degradation of PEFCs, with SEM used for ex-situ visualisation of platinum in the membrane [29]. Such non-uniform degradation has been reported by a number of practitioners, but, until now, only in 2D, ex-situ SEM studies [11,[28][29][30] or by using nano-scale techniques, like X-ray absorption fine structure (XAFS) or scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) [31]. However, 3D imaging of the microstructural degradation effects that accompany localised electrochemical degradation have not been demonstrated.…”

Advancement of Segmented Cell Technology in Low Temperature Hydrogen Technologies

“…As a rule of thumb, several issues are reversible after a shutdown-restart event, or after a period of dynamic operation. High levels of irreversible degradation, as shown in Figure 7, are very likely not homogeneously distributed [80,81]. The irreversible parts of degradation rates after~500 h of dynamic operation (coloured dots, low degradation rate) and of constant operation (grey dots, high degradation rate) are depicted, and corresponding current density patterns before (BoT) and at the end (EoT) of the 500 h are correlated at the example of a 0.1 A/cm 2 constant load test (upper pair of current density distribution images) and a dynamic operation test (lower pair).…”

The degradation effect on proton dissociation and transfer in perfluorosulfonic acid membranes

“…The results showed that the water absorption of ionomers increased significantly with the degradation, whereas the proton conductivity had a linear decrease. According to the study of Garcia-Sanchez et al , 28 the ohmic high frequency resistance was increased after membrane degradation owing to the loss of side groups and the proton transport properties of the ionomers were affected. Although some studies about proton transport with membrane degradation have been conducted, the study of the proton transfer mechanism after membrane degradation is lacking.…”