Designing multifunctional materials for proton exchange membrane fuel cells

• Forschungsstelle: BFE
• Projektnummer: SI/501129

Schlüsselwörter (Englisch)

Proton exchange membrane fuel cells (PEM, PEFC), pore-scale model, multiphysics, 3D microstructure analysis, multifunctional marerials

Kurzbeschreibung (Englisch)

The aim of this project is to design multifunctional materials for polymer electrolyte fuel cells (PEFC) with customised local transport properties (particularly for the transport of liquid water). It combines experimental investigations with multi-physics modeling and microstructure analysis at different lengths scales. This project about IPEM Fuel Cells is part of the SNF/NFP70 umbrellaproject "Reduction and reuse of CO2: renewable fuels for efficient electricity production".

Schlussbericht (Englisch)

Microstructure characterization of both dry and partially saturated gas diffusion layers (GDLs) has been accomplished. X-ray tomographic images under different compression levels allowed for the deduction of porous material properties. New improved quantitative relationships between GDL microstructure and effective transport properties have been established. Ex-situ experiments of GDLs imbibed with liquid water were carried out. The dependency of microstructure features on liquid water saturation lead to new insight on finite size effects in thin porous media, delivering valuable input for macro-homogeneous models.

To enhance the understanding of effects governing liquid water distribution in the pore space of GDLs, a 3D pore-scale Monte Carlo model has been developed and validated, which minimizes the surface free energy of the water. Simulation results on the water distribution in real GDL geometries were compared to the experiments.

To develop multifunctional materials for improved PEFC performance, better understanding of the liquid water interface between GDL and gas channels is needed. Fast X-ray tomographic microscopy has been applied to study the dynamic pressure-saturation relationship and droplet formation and removal in the vicinity of the interface. An analytical model of the same mechanism has been developed, and the dynamic response of water saturation levels in GDLs to such boundary conditions has been studied.

Macrohomogeneous models of the membrane electrode assembly and of small area PEFCs have been developed. The material parameterizations of these models were revised, and simulated cell performance was compared to measurement data. The combination of microstructure analysis of porous materials and macrohomogeneous fuel cell performance simulation is applied for the design of multifunctional materials, that is, to develop new porous transport layers and membrane electrode assemblies. The methodology is interesting for companies in the value added chain of hydrogen fueled electric vehicles, other PEFC powered electric devices but also for electrochemical cells like redox flow cells for the storage of electricity from solar cells or wind mills.

A web page is being created for the marketing of mathematical models of electrochemical cells, offering consulting to companies and laboratories, and to disseminate selected project results.

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• Final report [PDF] 8'243 kB