4th International Congress on 3D Materials Science (3DMS) 2018: Energy Materials II
Program Organizers: Hugh Simons, Denmark Technical University; Henning Poulsen, Denmark Technical University; David Rowenhorst, Naval Research Laboratory; Peter Voorhees, Northwestern University; Satoshi Hata, Kyushu Univ; McLean Echlin, UC Santa Barbara

Tuesday 1:30 PM
June 12, 2018
Room: Store Scene
Location: Kulturværftet (Culture Yard) Conference Center

Session Chair: Jens Andreasen, Technical University of Denmark

1:30 PM  Invited
Phase-field Modeling on 3D Microstructure in Li-ion Battery Electrodes: Baixiang Xu1; Ying Zhao2; Peter Stein1; 1Tu Darmstadt; 2Cambridge University
    Li-ion batteries are currently the most important energy storage technology. For both the functionality and the performance improvement, physical or designed spatially complex microstructure plays a critical role. For instance, new electrode materials involve phase separation during (de-)lithiation. Compared with dilute solution case, phase separation enhances heterogeneity and thus leads to harsher mechanical situation, which was deemed as one of the major degradation mechanisms of the battery. The composite structure of electrodes has also large impact on the effective conductivity of electrolyte, the electrochemical reaction and mechanical stability. Employing a multiphysics phase field theory and advanced 3D finite element simulations, we investigate the electrochemical and mechanical behavior of electrode particles during (de-)lithiation. Simulations demonstrate that phase separation results in an intensified stress field and enhanced electrochemical reaction and even the crack propagation. Extensive simulations are carried out to explore the factors that contribute to the phase separation and battery performance.

2:00 PM  
Time-resolved Neutron Radiography and Tomography of Red-ox Cycled Electrodes for Solid Oxide Electrochemical Cells: Luise Kuhn1; Malgorzata Makowska2; Monica Lacatusu1; Salvatore De Angelis1; Henrik Frandsen1; Erik Lauridsen3; Ingo Manke4; Manuel Morgano5; Markus Strobl5; Nikolay Kardjilov4; 1Technical University of Denmark; 2Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II); 3Xnovo Technology Aps; 4Helmholtz-Zentrum Berlin fur Materialien und Energie; 5Paul Scherrer Institute
    We are reporting a combined study by time-resolved neutron radiography and tomography of red-ox cycling of electrodes for solid oxide electrochemical cells to analyze the degree of reduction/oxidation and e.g. crack formation. NiO/Ni-8YSZ (nickel/nickel oxide – yttria stabilized zirconia) are often used as electrodes in solid oxide electrochemical cells for efficient energy conversion (power-to-gas and vice versa) purposes. Results of in-situ 2D and ex-situ 3D measurements are presented. In-situ observation of phase transition between NiO and Ni were performed at BOA at the continuous neutron source SINQ at the Paul Scherrer Institute by monochromatic neutron imaging, and post mortem monochromatic neutron tomography was performed at CONRAD-2 at Helmholtz Zentrum Berlin at the BER II reactor. Combining both time resolved radiography and post mortem tomography, provides complementary information about the rate of chemical reactions and spatial evolution of phases and morphological changes, e.g. crack formation and thereby degradation of the electrodes.

2:20 PM  
A Modelling Investigation of Solid Oxide Cells Degradation Based on Synchrotron X-ray Nanotomography Characterization: Maxime Hubert1; Jerome Laurencin2; Florence Lefebvre-Joud2; Peter Cloetens1; 1European Synchrotron Radiation Facility; 2CEA
    The degradation of Solid Oxide Cells operating at high temperature is detrimental to consider their industrial deployment on a large scale. An approach based on electrochemical tests, advanced post-mortem characterization and multi-scale models has been used to investigate the link between the performances, the electrodes microstructure and their degradation upon operation. X-ray holographic nanotomography has been optimised at the ESRF to improve the spatial resolution and become virtually free of artefacts. It allows extracting the slow microstructural evolution in the Ni-YSZ hydrogen electrode. A physically-based model for Nickel agglomeration has been adjusted on the analysis performed on the 3D volumes and implemented in an in-house multi-scale modelling framework. The model has been used to quantify the contribution of Nickel agglomeration on the total degradation measured experimentally.

2:40 PM  
3D Modelling of Ferroelectric Composite Properties using X-ray Micro Tomography Images: Effective Permittivity and Tunability: Dominique Bernard1; Catherine Elissalde1; Claude Estournes2; Julien Lesseur3; Erwan Plougonven4; Mario Maglione1; 1ICMCB-CNRS; 2CIRIMAT; 3RXSolutions; 4University of Liège
     Ferroelectric materials are widely used in microelectronics and different approaches are explored to produce new materials. In the composite approach, dielectric particles are introduced in a ferroelectric powder to obtain by SPS a composite with dielectric inclusions distributed within a ferroelectric matrix. This presentation focussed on the final step where, for the same sample, measured and computed permittivities can be compared. We first exposed the numerical problem at the scale characterised by XCMT. Then, it is shown that the model reproduces the permittivity anisotropy induced by the deformation of the dielectric inclusions due to SPS. For tunability (permittivity variation with the applied electric field), Johnson's law is used as constitutive law and the dimensionless problem puts into evidence the main parameters. Fitting numerical and experimental results, this law allows reproducing the experimental data with precision, but requiring the introduction of an anisotropic non-linear coefficient. Consequences of this result are discussed.

3:00 PM  
Characterization of Three Dimensional Transport Networks in a Long-Term Tested Solid Oxide Electrolysis Cell: Peter S. Jørgensen1; Ming Chen1; Jacob R. Bowen1; 1Technical University of Denmark
    Solid oxide electrolysis cell (SOEC) is a promising technology for energy conversion and storage. The SOEC cell consists of two electrodes on each side of a dense electrolyte. The electrodes are typically a two- or three-phase porous system, where the solid phases are responsible for conduction of electrons and oxygen ions and the pore phase allows transport of reactants and products to and from the electrochemically active sites. In this work we present a study of three dimensional transport networks in a long-term tested SOEC. The difference in the transport network quality at different cell locations was compared in terms of 3D microstructure parameters calculated from FIB serial sectioning image data. An advanced 3D transport network analysis was performed through simulations and geometrical calculations. Dramatic differences were observed between the gas inlet and outlet in the cell. The obtained 3D transport characteristics correlated well with the measured cell electrochemical performance.

3:20 PM Break