Computational Model for Predicting Particle Fracture During Electrode Calendering

In the context of calling for low carbon emissions, lithium-ion batteries (LIBs) have been widely concerned as a power source for electric vehicles, so the fundamental science behind their manufacturing has attracted much attention in recent years. Calendering is an important step of the LIB electrode manufacturing process, and the changes it brings to the electrode microstructure and mechanical properties are worth studying. In this work, we reported the observed cracking of active material (AM) particles due to calendering pressure under ex situ nano-X-ray tomography experiments. We developed a 3D-resolved discrete element method (DEM) model with bonded connections to physically mimic the calendering process using real AM particle shapes derived from the tomography experiments. The DEM model can well predict the change of the morphology of the dry electrode under pressure, and the changes of the applied pressure and porosity are consistent with the experimental values. At the same time, the model is able to simulate the secondary AM particles cracking by the fracture of the bond under force. Our model is the first of its kind being able to predict the fracture of the secondary particles along the calendering process. This work provides a tool for guidance in the manufacturing of optimized LIB electrodes

Binder-free CNT cathodes for Li-O2_2 batteries with more than one life

Li-O$_2$ batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, we establish a facile method to fabricate free-standing, binder-free electrodes for LOBs in which multi-wall carbon nanotubes (MWCNT) form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate high reproducibility upon cycling in LOBs. After cell death, efficient and inexpensive methods to wash away the accumulated discharge products are demonstrated, as reconditioning method. The second life usage of these electrodes is validated, without noticeable loss of performance. These findings aim to assist in the development of greener high energy density batteries while reducing manufacturing and recycling costs.Comment: 24 pages, 6 figures, 10 figures in S

Adorym: A multi-platform generic x-ray image reconstruction framework based on automatic differentiation

We describe and demonstrate an optimization-based x-ray image reconstruction framework called Adorym. Our framework provides a generic forward model, allowing one code framework to be used for a wide range of imaging methods ranging from near-field holography to and fly-scan ptychographic tomography. By using automatic differentiation for optimization, Adorym has the flexibility to refine experimental parameters including probe positions, multiple hologram alignment, and object tilts. It is written with strong support for parallel processing, allowing large datasets to be processed on high-performance computing systems. We demonstrate its use on several experimental datasets to show improved image quality through parameter refinement

Reversible magnesium and aluminium ions insertion in cation-deficient anatase TiO₂

International audienc

Synthèse, caractérisations structurales et auto-organisations de nanocristaux (alliages COxPt100-x et nanocubes de Pt)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Lithium Ion Battery Electrode Calendering Study By Combining X-Ray Computed Tomography and 3D-Resolved Physical Process Models

International audienceSignificant amount of research has been done recently on how to increase energy densities while maintaining or lowering costs in response to the growing demand for lithium-ion batteries (LIBs). In order to achieve optimization of the manufacturing process of batteries, it is essential to understand the influence of each process stage on the architectures of the electrodes, which affects the energy, power, lifetime and safety of the LIB cells. Our ERC-funded ARTISTIC project 1 develops a digital twin that enables predicting the electrode architectures and their electrochemical performances from parameters at each stage of the LIBs manufacturing process. In this work, we present our most recent research, which studies the manufacturing process of LiNi x Mn y Co 1-x-y O 2 (NMC)-based cathodes and especially focuses on the electrode calendering stage 2 . Our methodology encompasses coarse-grained molecular dynamics and discrete element method to simulate the calendering process of electrodes that are virtually produced after the drying and slurry simulations. In this new work, we account in our model for non-spherical NMC secondary particles with realistic 3D shapes derived by X-ray computed tomography (XCT), together with spherical particles representing the carbon binder domain. An in situ compressing micro-XCT experiment is carried out on the NMC electrode to monitor the change of the electrode morphology upon the calendering process. The findings from the simulation are validated by comparing our predicted electrode architectures with the experimental ones. Our approach captures the alterations in orientation of the secondary particles throughout the calendering processes and the relaxation process, as well as their possible deformation and spring back effect brought on by the pressure. Additionally, we discuss the comparison of variations in porosity, tortuosity factor, conductivity, different phases distribution and pore size distribution during the calendering process. ERC Artistic : Home Artistic. http://www.erc-artistic.eu/. Xu, J., Ngandjong, A.C., Liu, C., Zanotto, F.M., Arcelus, O., Demortière, A., and Franco, A.A. (2023). Lithium ion battery electrode manufacturing model accounting for 3D realistic shapes of active material particles. Journal of Power Sources 554 , 232294. 10.1016/j.jpowsour.2022.232294

Thick Binder-Free Electrodes for Li-Ion Battery Fabricated Using Templating Approach and Spark Plasma Sintering Reveals High Areal Capacity

International audienceThe templating approach is a powerful method for preparing porous electrodes with interconnected well-controlled pore sizes and morphologies. The optimization of the pore architecture design facilitates electrolyte penetration and provides a rapid diffusion path for lithium ions, which becomes even more crucial for thick porous electrodes. Here, NaCl microsize particles are used as a templating agent for the fabrication of 1 mm thick porous LiFePO4 and Li4Ti5O12 composite electrodes using spark plasma sintering technique. These sintered binder-free electrodes are self-supported and present a large porosity (40%) with relatively uniform pores. The electrochemical performances of half and full batteries reveal a remarkable specific areal capacity (20 mA h cm(-2)), which is 4 times higher than those of 100 mu m thick electrodes present in conventional tape-casted Li-ion batteries (5 mA h cm(-2)). The 3D morphological study is carried out using full field transmission X-ray microscopy in microcomputed tomography mode to obtain tortuosity values and pore size distributions leading to a strong correlation with their electrochemical properties. These results also demonstrate that the coupling between the salt templating method and the spark plasma sintering technique turns out to be a promising way to fabricate thick electrodes with high energy density

High Accuracy Battery Modeling : Fully 3D-Resolved Lithium-Ion Battery Mesostructure Including Carbon Binder Domains

In the literature, reported 3D-resolved models rely on oversimplifications, such as an implicit representation of the carbon-binder domains (CBD) through the use of effective parameters for porosity and tortuosity or by merging CBD with the Active Material (AM) as a single solid phase. This work’s novelty relies on the explicit representation of CBD, leading to a new level of accuracy in terms of electrochemical modeling. This achievement is made possible thanks to an in-house algorithm, called INfinite Number Of phases meshing through Voxelization (INNOV) [1] . INNOV can generate a volumetric mesh from data of different types due to its flexible input format. INNOV takes as input binary stack of images to reconstruct the 3D structure. Such an input can result from tomography imaging, from slicing a 3D object or from Coarse Grained Molecular Dynamics (CGMD) simulations [2] . For the latter a function has been developed to convert its output (coordinates of the centers and radii of the particles) into a binary stack of images. The segmentation method of Nielson and Franke [3] has been translated and optimized for MATLAB language and modified to suit the COMSOL Multiphysics meshing importation process. This algorithm is designed in the scope of the ARTISTIC Project [4] to import a multi-phase volumetric mesh of an electrode (from a CGMD simulation) into COMSOL Multiphysics to simulate the performances of the cell. The core of this work is to increase the current level of precision of the modeling of batteries by separating active and inactive materials. In doing so, one must not sacrifice the integrity of the mesostructure geometry. To ensure this, INNOV provides a number of observables, which can be compared to experimental numbers (e.g. arising from tomography characterizations). Once the integrity of the mesh is ensured, electrochemical simulations can be done to characterize the structure (Figure 1). Such characterizations can capture the role of CBD to further understand the limiting phenomena and predict the optimal LIB structure to achieve the optimization of the fabrication process. Simulations on NMC/Li half-cell have been carried out to demonstrate the versatility of this algorithm. In conclusion, INNOV offers a time-efficient tool to perform meshing without requiring substantial computational resources. Simulations can later be performed to characterize these meshes with the CBD explicitly considered. It is also a powerful tool to couple with tomography imaging. FIGURE TABLE Figure 1. From CGMD simulation to a volumetric mesh (35.1*35.1*42 µm). In yellow is the CBD, in red the AM. At the far right is the discharge curve for this specific mesh with COMSOL. REFERENCES [1] M. Chouchane, A. Rucci, A.A. Franco (submitted 2019) [2] A.C. Ngandjong et al. Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. J. Phys. Chem. Lett. (2017). 5966–5972 doi:10.1021/acs.jpclett.7b02647 [3] G.M. Nielson, R. Franke Computing the separating surface for segmented data. IEEE Vis. (1997). 229–233 doi:10.1097/MOP.0000000000000041 [4] https://www.u-picardie.fr/erc-artistic/ Figure 1 <jats:p /