15 results found
© 2017 The Authors This paper describes the use of a frequency domain, finite-difference scheme to simulate the impedance spectra of diffusion in porous microstructures. Both open and closed systems are investigated for a range of ideal geometries, as well as some randomly generated synthetic volumes and tomographically derived microstructural data. In many cases, the spectra deviate significantly from the conventional Warburg-type elements typically used to represent diffusion in equivalent circuit analysis. A key finding is that certain microstructures show multiple peaks in the complex plane, which may be misinterpreted as separate electrochemical processes in real impedance data. This is relevant to battery electrode design as the techniques for nano-scale fabrication become more widespread. This simulation tool is provided as an open-source MatLab application and is freely available online as part of the TauFactor platform.
Cooper SJ, Niania M, Hoffmann F, et al., 2017, Back-exchange: a novel approach to quantifying oxygen diffusion and surface exchange in ambient atmospheres, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 12199-12205, ISSN: 1463-9076
Cooper SJ, brandon NP, 2017, Solid Oxide Fuel Cell Lifetime and Reliability, Solid Oxide Fuel Cell Lifetime and Reliability Critical Challenges in Fuel Cells, Editors: Ruiz-Trejo, BOLDRIN, Publisher: Academic Press, Pages: 1-15, ISBN: 9780128097243
For its holistic approach, this book can be used both as an introduction to these issues and a reference resource for all involved in research and application of solid oxide fuel cells, especially those developing understanding in ...
Cooper SJ, Bertei A, Shearing PR, et al., 2016, TauFactor: An open-source application for calculating tortuosity factors from tomographic data, SoftwareX, Vol: 5, Pages: 203-210
© 2016 The Author(s) TauFactor is a MatLab application for efficiently calculating the tortuosity factor, as well as volume fractions, surface areas and triple phase boundary densities, from image based microstructural data. The tortuosity factor quantifies the apparent decrease in diffusive transport resulting from convolutions of the flow paths through porous media. TauFactor was originally developed to improve the understanding of electrode microstructures for batteries and fuel cells; however, the tortuosity factor has been of interest to a wide range of disciplines for over a century, including geoscience, biology and optics. It is still common practice to use correlations, such as that developed by Bruggeman, to approximate the tortuosity factor, but in recent years the increasing availability of 3D imaging techniques has spurred interest in calculating this quantity more directly. This tool provides a fast and accurate computational platform applicable to the big datasets ( > 10 8 voxels) typical of modern tomography, without requiring high computational power.
Finegan DP, Cooper SJ, Tjaden B, et al., 2016, Characterising the structural properties of polymer separators for lithium-ion batteries in 3D using phase contrast X-ray microscopy, JOURNAL OF POWER SOURCES, Vol: 333, Pages: 184-192, ISSN: 0378-7753
Ni N, Cooper SJ, Williams R, et al., 2016, Degradation of (La0.6Sr0.4)(0.95)(Co0.2Fe0.8)O3-delta Solid Oxide Fuel Cell Cathodes at the Nanometer Scale and below, ACS APPLIED MATERIALS & INTERFACES, Vol: 8, Pages: 17360-17370, ISSN: 1944-8244
Tjaden B, Cooper SJ, Brett DJL, et al., 2016, On the origin and application of the Bruggeman correlation for analysing transport phenomena in electrochemical systems, CURRENT OPINION IN CHEMICAL ENGINEERING, Vol: 12, Pages: 44-51, ISSN: 2211-3398
Cooper SJ, Li T, Bradley RS, et al., 2015, Multi length-scale quantification of hierarchical microstructure in designed microtubular SOFC electrodes, Pages: 1857-1864, ISSN: 1938-5862
© The Electrochemical Society. The transport properties of a micro-tubular solid oxide fuel cell (MT-SOFC) anode have been analysed by imaging and simulation at multiple length-scales. The anode support investigated was manufactured using a phase inversion-assisted co-extrusion process, which generated a hierarchical and highly anisotropic microstructure. The resulting pore network was observed to contain two distinct, but interacting transport systems. The features in these systems spanned several orders of magnitude and as such it was not possible to image or model them simultaneously. The simulations indicated that the design of the microstructure was beneficial for the radial transport required by these cells; however this conclusion was only obtained by considering diffusive systems at many length-scales.
Tariq F, Kishimoto M, Cui G, et al., 2015, Advanced 3D imaging and analysis of SOFC electrodes, Pages: 2067-2074, ISSN: 1938-5862
© The Electrochemical Society. An ability to meet our increasing energy demands will be facilitated though improving the next generation of electrochemical devices. The ability to directly image in 3D and analyse solid oxide fuel cell (SOFC) electrodes at high resolutions provides key insights in understanding structure-property relationships; as electrochemical reactions and transport phenomena are strongly affected by complex microstructure. Here we use tomographic techniques to probe 3D electrode structures at nanometer to micrometer length scales. In doing so the first characterisation of specific necks and interfaces alongside their particle sizes within SOFC electrodes is derived. Micro/nano structural changes are followed to facilitate understanding the differences which occur with shape, structures and morphology at high resolution. These are correlated with both measured experimental values and simulations to provide insight into microstructure-property relationships. We also demonstrate approaches to intelligently design electrodes through scaffolds, and potentially 3D printed structures, all towards optimising the structure for performance.
Cooper SJ, Eastwood DS, Gelb J, et al., 2014, Image based modelling of microstructural heterogeneity in LiFePO4 electrodes for Li-ion batteries, JOURNAL OF POWER SOURCES, Vol: 247, Pages: 1033-1039, ISSN: 0378-7753
Eastwood DS, Bradley RS, Tariq F, et al., 2014, The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Vol: 324, Pages: 118-123, ISSN: 0168-583X
Cooper SJ, Kishimoto M, Tariq F, et al., 2013, Microstructural Analysis of an LSCF Cathode Using In-Situ Tomography and Simulation, SOLID OXIDE FUEL CELLS 13 (SOFC-XIII), Vol: 57, Pages: 2671-2678, ISSN: 1938-5862
Shearing PR, Eastwood DS, Bradley RS, et al., 2013, Exploring electrochemical devices using X-ray microscopy: 3D microstructure of batteries and fuel cells, Microscopy and Analysis, Vol: 27
Tariq F, Kishimoto M, Cooper SJ, et al., 2013, Advanced 3D Imaging and Analysis of SOFC Electrodes, SOLID OXIDE FUEL CELLS 13 (SOFC-XIII), Vol: 57, Pages: 2553-2562, ISSN: 1938-5862
Shearing PR, Brandon NP, Gelb J, et al., 2012, Multi Length Scale Microstructural Investigations of a Commercially Available Li-Ion Battery Electrode, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 159, Pages: A1023-A1027, ISSN: 0013-4651
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