Accelerated Degradation of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

Abstract

In this work, as-received pristine GDLs were degraded (aged) through an accelerated ageing process by immersion into a 35% wt. solution of H 2 O 2 at 90 • C for 12 hours. Pristine and degraded GDLs were assembled in custom-built fuel cells for in operando synchrotron X-ray visualization. Electrochemical impedance spectroscopy (EIS) measurements were obtained, while synchrotron X-ray radiography was performed to investigate the effect of ageing on liquid water transport behavior. In both pristine and aged GDLs, the liquid water profile converged to an upper (terminal) threshold in the saturation pattern as the current density increased. The terminal steady state liquid water profile was established at a lower current density for the aged GDLs compared to that of the pristine GDLs. Higher water quantities of liquid water accumulated at the GDL/flow field channel and MPL/carbon fiber substrate interfaces of the fuel cell with an aged GDL compared to the fuel cell with a pristine GDL. The aged GDLs exhibited more liquid water accumulation at lower current densities. Increases in liquid water accumulation and reduced performance were attributed to the reduction in hydrophobicity of the GDL.

Liquid water saturation and oxygen transport resistance in polymer electrolyte membrane fuel cell gas diffusion layers

“…A variation in the liquid water saturation between GDL regions above the flow field lands and channels has also been observed by multiple studies [17,31,33,84,[86][87][88]. Therefore, it is important to consider in-plane variations of liquid water saturation when considering the oxygen transport resistance.…”

Water transport in polymer electrolyte membrane fuel cell: Degradation effect of gas diffusion layer

“…Their degradation was affected significantly by the concentration of H 2 O 2 and the degradation time. 34 In the present study, these conditions were determined based on a previous study. 20 After aging, the degraded GDLs were washed and subsequently soaked in distilled water for 24 hours to remove residual H 2 O 2 .…”

“…Commercially available pristine carbon paper GDLs (SGL 39 BB) manufactured by SGL Group (Sigracet GmbH) were placed in a 30 wt% H 2 O 2 solution at 90°C for 24 hours. Their degradation was affected significantly by the concentration of H 2 O 2 and the degradation time 34 . In the present study, these conditions were determined based on a previous study 20 .…”

In Situ and Operando Characterization of Proton Exchange Membrane Fuel Cells

“…[76a] An increase in water content in the gas-diffusion layer for aged PEMFCs has been reported using X-CT, demonstrating a loss of hydrophobicity after operation. [77] Although powerful, micro X-CT can only image small samples, due to the trade-off between the resolution and field-of-view of the X-ray. Further insight into the water pathway through the microporous layer and carbon-fiber paper has been visualized with soft X-rays (Figure 5b), and by Xray radiography (Figure 5c).…”