Imaging the Electrode-GDL Interface by a Modified Wood's Intrusion Process

Abstract

The structure of the interface between the gas diffusion layer (GDL) and the electrode is extremely important for the fuel cell's performance. However, although numerous methods exist for the analysis of either the GDL or the membrane-electrode assembly (MEA), not many techniques render themselves suitable for the simultaneous imaging of both components. Electron microscopy would be an option, but the preparation of cross-sections is extremely demanding due to the materials' different mechanical properties. This paper presents a sample preparation technique using the intrusion with low-melting Wood's metal, which stabilizes the porous GDL-electrode interface and enables its cutting into thin sections. Using this alternative approach, a considerable influence of the structure of the GDL on the electrode morphology could be demonstrated. In regions, where the fiber bundles from the backing recede from the membrane, delamination occurs more frequently. Furthermore, penetration of the MPL into the carbon fiber backing was observed.

Optimizing the Electrochemical Reduction of CO2 to Formate: A State-of-the-Art Analysis

“…The GDL has four main roles. It must conduct electrons to the catalyst layer, 82,84 be mechanically stable, 85 supply reactant feed to the catalyst, 78,82 and maintain the three-phase boundary by keeping water at the catalyst layer to prevent flooding. 78,82 The GDE is ineffective if any of these conditions are not met.…”

“…The GDL has four main roles. It must conduct electrons to the catalyst layer, , be mechanically stable, supply reactant feed to the catalyst, , and maintain the three-phase boundary by keeping water at the catalyst layer to prevent flooding. , The GDE is ineffective if any of these conditions are not met. Furthermore, the ideal GDL should be capable of providing a high number of gas dissolving sites when combined with the catalyst layer. , Therefore, the characteristics of a GDL will strongly impact the performance of the complete electrode.…”

Pore Structural Characterization of Fuel Cell Layers Using Integrated Mercury Porosimetry and Computerized X-ray Tomography

“…6 Scheiba and co-workers used a Wood's metal intrusion process to study the electrode−gas diffusion layer (GDL) interface, though this method requires slicing and polishing sections and thus is destructive. 7 Hellmuth and co-workers studied mercury entrapped in macroporosity in rocks. 8 However, previous use of CXT combined with mercury porosimetry has generally looked at macroporosity, rather than lower-scale properties of materials.…”

“…Mann and co-workers studied low melting point alloy intrusion into the macropore network of an alumina catalyst pellet using X-ray tomography . Scheiba and co-workers used a Wood’s metal intrusion process to study the electrode–gas diffusion layer (GDL) interface, though this method requires slicing and polishing sections and thus is destructive . Hellmuth and co-workers studied mercury entrapped in macroporosity in rocks .…”

Spatially Resolved Contact Pressure and Contact Resistance Measurements at the Gas Diffusion Layer: A Tool for PEM Fuel Cell Development

“…This circumstance highlights the importance of the contact between the GDL and the CCM in the middle of the channel. In extreme cases, a delamination of the GDL from the CCM under inhomogeneous compression causes an isolation of the active area 10 which can affect the performance of a whole stack. 11 Regarding recent findings, the shear modulus in through-plane direction turned out to be a crucial parameter in order to model the mechanical behavior of the GDL within the land/channel area.…”