Degradation performance decay

Fig. 8.24 Example of calculated competitive materials aging impact on the global cell performance decay for several operation condition, (a) constant cnnent impact on the performance decay for two cathode relative humidities and three current values with the description of Pt/C degradation only vs. the description of both Pl/C and membrane degradation, (b) cycled vs. constant current impact on the PEM degradatimi (Source [219])...

Cell performance decay on cycling results from the following causes (1) anode crystal structure degradation [45-47], (2) cathode crystal structure degradation [22,48-50], (3) electrode/electrolyte interface properties degradation [51-53], (4) metal dissolution [54-56], (5) electrolyte decomposition [57-60], and (6) surface film formation [60,61],... 

It can be seen that the degradation rate, which is the rate at which the cell performance decays to the steady-state plateau, is a function of toluene concentration, current density, and toluene exposure time. Figure 3.19... 

Membrane degradation is one of the main modes for PEMFC performance decay and eventual failure. Such degradation can take place via... 

The model has been successfully used to enhance the cathode CL stmcture to mitigate the reversible and irreversible performance degradations (Fig. 11.16). The impact of water flooding on the MEA performance decay was well reproduced by the model the increase of Pt loading per rmit of CL pore voltrme enhances potential decay as the local water production and thus flooding is enhanced, which can, in tirm, enhance Pt dissolution and C corrosion (both, water corrterrt-dependerrt mechanisms). 

Continued, (b) Calculated impact of a square cycle operation (0.1-0.5 A.cm, period = 30 min) on the performance decay and deconvolution of the contribution of the different aging mechanisms, (c) Calculated cumulative materials mass losses in the air inlet side and in the air outlet side of the cathode and PEM, andTEM images comparing the cathode inlet vs outlet CL microstructure after the degradation experiment (7= 27 °C, = 1.5 bar, RH = RH = 100%, =... 

Degradation of metallic bipolar plates can be constrained on two main mechanisms (a) the increase of ohmic losses due to the formation of electrical passivation films on the bipolar plate s surface during cell operation (b) the dissolution of metallic base material in the aggressive acidic environment of PEM fuel cell causing a contamination of the ME A by leached metafile ions leading to a cell performance decay. 

In this book s earlier chapters, the various components of fuel cell performance decay mechanisms were introduced. This chapter will cover fuel cell performance degradation under different operating cycles, and describe various mitigation strategies imder actual application conditions. 

Lifetime performance degradation is a key performance parameter in a fuel cell system, but the causes of this degradation are not fully understood. The sources of voltage decay are kinetic or activation loss, ohmic or resistive loss, loss of mass transport, or loss of reformate tolerance (17). 

The characterization of the degradation process can be performed by analysing the time dependence of the decay of specific absorption bands at 1506 cm-1 (MDMO-PPV) and 1182 cm 1 (Ceo) using spectral fitting techniques. The results are shown in Fig. 5.54. For the individual components,... 

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