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•One and the same type of a parametric stochastic 3D model is fitted to eight differently compacted cathodes.•The proposed model is validated by means of phase-based and ...particle-based characteristics.•The suitability of the model for interpolation and extrapolation is investigated by means of leave-one-out cross validation.•Predictive simulations are carried out by predicting the model parameters as a function of the compaction load.
The microstructure of electrodes significantly influences the electrochemical performance of lithium-ion batteries. Thus, a deeper understanding of the electrode microstructure provides valuable information for the design of optimized electrode morphologies. One promising approach is called virtual materials testing, where stochastic microstructure models are used for generating a large number of virtual, but realistic morphologies, which serve as input for numerical transport simulations. Doing so, relationships between the microstructure and functional properties of the electrodes can be investigated. In the present paper, we utilize a parametric stochastic microstructure model, which is calibrated to tomographic image data of eight differently manufactured cathodes, where the compaction load has been varied. Since one and the same model type is used for all compaction loads, we can predict the model parameters for an arbitrary compaction load. This allows us to perform predictive simulations, i.e., we are able to generate virtual microstructures that correspond to a compaction load which has not been observed experimentally. The goodness of fit of the microstructure model is validated by comparing phase-based as well as particle-based characteristics of model realizations and tomographic image data. In addition, the suitability of the stochastic microstructure model for predictive simulations is pointed out by cross-validation.
A large and increasing number of scientific domains pushes for high neutron imaging resolution achieved in reasonable times. Here we present the principle, design and performance of a detector based ...on infinity corrected optics combined with a crystalline Gd
Ga
O
: Eu scintillator, which provides an isotropic sub-4 µm true resolution. The exposure times are only of a few minutes per image. This is made possible also by the uniquely intense cold neutron flux available at the imaging beamline NeXT-Grenoble. These comparatively rapid acquisitions are compatible with multiple high quality tomographic acquisitions, opening new venues for in-operando testing, as briefly exemplified here.
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An in-depth understanding of the degradation mechanisms is a prerequisite for developing the next-generation all solid-state lithium metal battery (ASSLMB) technology. Herein, ...synchrotron X-ray computed tomography (SXCT) together with other probing tools and simulation method were employed to rediscover the decaying mechanisms of LiNi0.8Co0.1Mn0.1O2 (NCM)|Li6PS5Cl (LPSCl)|Li ASSLMB. It reveals that the detachment and isolation of NCM particles cause the current focusing on the remaining active regions of cathode. The extent of Li stripping and the likelihood of Li+ plating into LPSCl facing the active NCM particles becomes higher. Besides, the homogeneity of Li stripping/plating is improved by homogenizing the electrochemical reactions at the cathode side by LiZr2(PO4)3 (LZP) coating. These results suggest a codependent failure mechanism between cathode and anode that is mediated by uneven Li ion flux. This work contributes to a holistic understanding of the degradation mechanisms in ASSLMBs and opens new opportunities for their further optimization and development.
Copper sulfide shows some unique physico‐chemical properties that make it appealing as a cathode active material (CAM) for solid‐state batteries (SSBs). The most peculiar feature of the electrode ...reaction is the reversible formation of µm‐sized Cu crystals during cycling, despite its large theoretical volume change (75%). Here, the dynamic microstructural evolution of CuS cathodes in SSBs is studied using in situ synchrotron X‐ray tomography. The formation of µm‐sized Cu within the CAM particles can be clearly followed. This process is accompanied by crack formation that can be prevented by increasing the stack pressure from 26 to 40 MPa. Both the Cu inclusions and cracks show a preferential orientation perpendicular to the cell stack pressure, which can be a result of a z‐oriented expansion of the CAM particles during lithiation. In addition, cycling leads to a z‐oriented reversible displacement of the cathode pellet, which is linked to the plating/stripping of the Li counter electrode. The pronounced structural changes cause pressure changes of up to 6 MPa within the cell, as determined by operando stack pressure measurements. Reasons for the reversibility of the electrode reaction are discussed and are attributed to the favorable combination of soft materials.
Using in situ X‐ray tomography, the phase transformation and microstructural evolution of a copper sulfide cathode in solid‐state batteries is 3D visualized and characterized. Copper inclusions generate after phase transformation and the electrode cracks have a strong preferential orientation within the x‐y plane of the cell. The particle expansion‐induced electrode displacement is more pronounced along z‐axis perpendicular to the cathode pellet.
The hard X‐ray beamline BAM
line
at BESSY II (Berlin, Germany) has now been in service for 20 years. Several improvements have been implemented in this time, and this review provides an overview of ...the imaging methods available at the BAM
line
. Besides classic full‐field synchrotron X‐ray computed tomography (SXCT), also absorption edge CT, synchrotron X‐ray refraction radiography (SXRR), and synchrotron X‐ray refraction tomography (SXRCT) are used for imaging. Moreover, virtually any of those techniques are currently coupled in situ or operando with ancillary equipment such as load rigs, furnaces, or potentiostats. Each of the available techniques is explained and both the current and the potential usage are described with corresponding examples. The potential use is manifold, the examples cover organic materials, composite materials, energy‐related materials, biological samples, and materials related to additive manufacturing. The article includes published examples as well as some unpublished applications.
Abstract Rechargeable sodium–oxygen batteries (NaOBs) are receiving extensive research interests because of their advantages such as ultrahigh energy density and cost efficiency. However, the severe ...failure of Na metal anodes has impeded the commercial development of NaOBs. Herein, combining in situ synchrotron X‐ray computed tomography (SXCT) and other complementary characterizations, a novel electro‐chemo‐mechanical failure mechanism of sodium metal anode in NaOBs is elucidated. It is visually showcased that the Na metal anodes involve a three‐stage decay evolution of a porous Na reactive interphase layer (NRIL): from the initially dot‐shaped voids evolved into the spindle‐shaped voids and the eventually‐developed ruptured cracks. The initiation of this three‐stage evolution begins with chemical‐resting and is exacerbated by further electrochemical cycling. From corrosion science and fracture mechanics, theoretical simulations suggest that the evolution of porous NRIL is driven by the concentrated stress at crack tips. The findings illustrate the importance of preventing electro‐chemo‐mechanical degradation of Na anodes in practically rechargeable NaOBs.
Adopting X-ray computed tomography (XCT) for ex-situ characterization of battery materials has gained interest in the past decade. The main goal of this paper is to demonstrate the effectiveness of ...several X-ray computer tomography techniques to study commercial batteries. General guidelines are provided to select the most suitable imaging equipment and parameters for investigations of lithium-ion batteries, spanning the length scales from cell to electrode, down to particle level. Relevantly, such parameters would also be suitable for operando experiments. Safety mechanisms and manufacturing inconsistencies at cell level as well as defects and inhomogeneity in cathode and anode is illustrated and quantified. Furthermore, relation of beam energy and sample-detector-distance on contrast retrieved from attenuation and phase shift is inspected using Synchrotron XCT.
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•Cone beam artifacts induced by data insufficiency are hindered by deviating vertical axis of the sample.•Qualitative correlation is given between sample size and the smallest measurable features using laboratory and synchrotron XCT on a commercial cell.•Cracks and defects in cathode material could be well measured using Region of interest XCT.•Low attenuating anode materials could be imaged by SXCT using contrast retrieved from phase shift
Understanding the complicated interplay of the continuously evolving electrode materials in their inherent 3D states during the battery operating condition is of great importance for advancing ...rechargeable battery research. In this regard, the synchrotron X‐ray tomography technique, which enables non‐destructive, multi‐scale, and 3D imaging of a variety of electrode components before/during/after battery operation, becomes an essential tool to deepen this understanding. The past few years have witnessed an increasingly growing interest in applying this technique in battery research. Hence, it is time to not only summarize the already obtained battery‐related knowledge by using this technique, but also to present a fundamental elucidation of this technique to boost future studies in battery research. To this end, this review firstly introduces the fundamental principles and experimental setups of the synchrotron X‐ray tomography technique. After that, a user guide to its application in battery research and examples of its applications in research of various types of batteries are presented. The current review ends with a discussion of the future opportunities of this technique for next‐generation rechargeable batteries research. It is expected that this review can enhance the reader's understanding of the synchrotron X‐ray tomography technique and stimulate new ideas and opportunities in battery research.
The current review focuses on the application of the synchrotron X‐ray tomography technique in battery research. Firstly, fundamental principles and experimental setups of this technique are detailed. Secondly, a user guide to its application in battery research and an extensive case summary are presented. The review ends with the discussion of the future opportunities of this technique for next‐generation battery research.
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An intrinsic knowledge gap between current understandings obtained experimentally and the underlying working or degradation mechanisms of rechargeable lithium batteries still remains, ...giving direct rise to application challenges, e.g., safety issues, predicaments in identifying performance-aging factors and dilemmas in guiding further research directions. Against this background, non-destructive and three-dimensional (synchrotron) X-ray tomography that guarantees a direct visual access to inner electrodes has been employed herein to: in-situ record the evolution of internal short circuits; characterize the behaviors of widely employed separators; investigate the morphological evolution of Li electrodes under different cycling conditions; and study the degradation mechanisms of Li/carbon cells. By incorporating the currently presented results with the previously published studies on those topics, a complete picture of the degradation mechanism of rechargeable lithium batteries has been painted. This advancement of mechanistic understanding supplies the missing pieces of information to bridge fundamental R&D research activities and practical applications.
We present a quantitative analysis of the influence of artificial ageing of gas diffusion layers (GDL) on the water distribution and transport in polymer electrolyte membrane fuel cells (PEMFCs) ...during cell operation. Water droplet size distributions are measured by means of in-operando neutron radiography. We find a strong correlation between droplet size distribution and GDL ageing time: With increasing GDL ageing, water droplet sizes in the flow field channels strongly decrease, indicating an ineffective water transport that leads to a reduced cell performance. This effect can be assigned to water accumulations on the GDL surface that block the gas supply towards the catalyst layer.
•Water droplet size distribution measured by means of neutron imaging.•Artificial GDL ageing applied to study effects on water distribution and transport.•Droplet sizes in flow field channels decrease with increasing GDL ageing.•Water on the GDL surface favourable blocks the gas supply with increasing GDL ageing.
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