Multiscale imaging and transport modeling for fuel cell electrodes
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FOCUS ISSUE
2017 MRS FALL
Multiscale imaging and transport modeling for fuel cell electrodes Jasna Jankovic1,a)
, Shawn Zhang2, Andreas Putz3, Madhu S. Saha4, Darija Susac4
1
Materials Science and Engineering Department, University of Connecticut, Storrs, Connecticut 06269-3136, USA; and Research and Development Department, Automotive Fuel Cell Cooperation Corporation, Burnaby, British Columbia V5J3J8, Canada 2 Research and Development Department, DigiM Solution LLC, Burlington, Massachusetts 01803, USA 3 Research and Development Department, MistyWest, Vancouver, British Columbia V5T2R5, Canada 4 Materials Science and Engineering Department, University of Connecticut, Storrs, Connecticut 06269-3136, USA a) Address all correspondence to this author. e-mail: [email protected] Received: 29 June 2018; accepted: 15 November 2018
Transport properties, performance, and durability of a proton exchange fuel cell (PEMFC) highly depend on microstructure and spatial distribution of components in the gas diffusion layer (GDL), microporous layer (MPL), and catalyst layers (CLs) of the fuel cell. Modeling of transport properties and understanding of these effects are challenging due to limited understanding of actual three-dimensional (3D) structure of the components, especially over a wide range of length scales. In this work, 3D imaging on multiple scales, namely electron tomography on a nanoscale, focused ion beam–scanning electron microscopy on a microscale, and 3D X-ray microscopy on a macroscale, was applied to obtain 3D reconstructions of the actual CL, MPL, and GDL microstructure. Direct numerical simulations on 3D data sets with an upscaling approach were applied to demonstrate the capability to simulate overall electrical conductivity of the system. Details of the process, challenges, and results are described.
Introduction Fuel cell components and microstructure Fuel cells are efficient, reliable, zero-emission power generation devices for automotive applications that offer extended driving range and fast refueling. They are considered one of the most promising long-term solutions for cleaner vehicles. Among several types of fuel cells, proton exchange membrane fuel cells (PEMFCs) are considered to be the closest to widespread commercialization for automotive applications [1]. However, challenges remain with respect to their efficiency, durability, and cost. In a PEMFC, power is generated in membrane electrode assembly (MEA) that comprises of gas diffusion layers (GDL), including microporous layers (MPLs), and porous cathode and anode catalyst layers (CLs), separated by a dense, protonconducting polymer membrane in the middle, as illustrated in Fig. 1. Each component of an MEA plays a crucial role in transport of species (electrons, protons, gases, and water) that support the electrochemical reactions in the CLs and the generation of power.
ª Materials Research Society 2019
The microstructures in PEMFCs are heterogeneous in length scales that span over a few orders of magnitude. GDL, for example, is a few
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