Durability membrane aging

Inflaming retarding t and electrostatic prevention were used in the fabric (Yu et al. 2010). A layer of cover membrane which has Inflame retarding t and electrostatic prevention formed on the surface of the fabric evenly. This method to a certain extent, improve the durability of the fabric with double proof, intensity is also improved. But the coating aging flame-retardant antistatic performance is poor, feel is also poor. 

However, traditional polymerizations always require a preengineered separator surface with active groups prior to grafting, which may involve complex even sometimes violet, multistep treatments, such as ultraviolet or heat. Inevitably, these treatments may introduce chemical residue (e.g., catalyst and initiator) and cause irreversible shrinkage and aging of the separators, which adversely degrade the electrochemical reaction and decrease the durability of the membrane. 

A fuel cell decays with time, and the rate of decay determines its durability. The decay is related to the aging of the fuel cell components, especially the membrane electrolyte, the catalysts, and the catalyst support. The decay of the membrane will cause its thinning and mechanical property deterioration. The loss of its mechanical properties often causes a fuel cell to fail prematurely and catastrophically. The decay of the catalyst is normally due to the particle size increase and the particle dissolution and redistribution. Catalyst decay rarely causes a sudden failure of a cell. The decay of the catalyst-support is often related to its corrosion. Corrosion makes the electrode more prone to flooding and accelerates the growth and redistribution of the catalyst particles. 

In brief, the Fenton test for pristine PBI membranes is informative as an aging tool for quaUtative comparison of the chemical stability of different materials. However, the test is apparently an overdoing method. The materials that withstand the test are surely durable in the real fuel cells, but those that cannot survive the test might still be sufficiently durable in fuel cells. 

A vast majority of fuel cell aging studies consider cell degradation as uniform over the cell surface process (Borup et al., 2007). However, nonuniformities dramatically accelerate the rate of local aging. In a fuel cell, any local inhomogeneity of transport or kinetic parameters induces inhomogeneity in the distribution of the membrane potential over the cell surface. This, in turn, inevitably leads to nonuniform overpotentials of parasitic electrochemical reactions running in the cell. Domains where the parasitic overpotential increases die much faster. Thus, modeling of nonuniformities in cells is important in the context of cell durability. 

Fig. 18 Before/after mercury porosimetry data for cell M2 showing changes in total specific pore volume after aging/Ufe testing GDLs aged in 80°C deionized water with air sparging for 1,006 h, then durabihty-tested with fresh 3 M CCM (30- Um Nafion membrane, 0.4mg Pt cm" per electrode) for 664 h at 1.00 A cm . See the Appendix for durability testing conditions...

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