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

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

Real-Time TEM Imaging of Moisture-Induced Degradation of Triple Cation Mixed Halide Perovskite

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Surface modification of LiFePO4 nanoparticles through an organic/ inorganic hybrid approach and its impact on electrochemical properties

International audienceChemical surface modification, using an hybrid organic/inorganic approach and its impact on the electrochemical response of a nanometric lithium iron phosphate obtained by the facile solvothermal method using an organic capping agent is investigated. Removal of the capping agent was realized through different approaches, such as washing with an organic solvent, chemical treatments, and ligand exchange with redox mediator having electrochemical activity close or not to the one of the material, to maintain the material's morphology and structure. The redox mediator grafting approach appears very interesting, since an unpredicted impact on the electrochemical activity of the material was observed. In that case, while materials structure and morphology are fully preserved, a more or less important change of the electrochemical curve shape depending on the redox potential of the grafted molecule was observed, which suggest that this approach could be a good alternative to traditional carbon coating, facilitate recycling and bring new functionalities to positive electrode materials

Oxidative decomposition products of synthetic NaFePO4 marićite: nano-textural and electrochemical characterization

International audience44 Single-phase marićite, NaFePO4, was synthesized from monosodium phosphate and 45 iron oxalate at 750°C, at atmospheric pressure. Thermal treatment of synthetic marićite in air 46 indicated oxidative decomposition into Na3Fe 3+ 2(PO4)3 nasicon and-Fe2O3 at temperatures 47 above 225°C. Intergrowth of the reaction products is found to occur at the nanoscale without 48 identified crystallographic relationship with the marićite precursor. Electrochemical activity of 49 the reaction product is confirmed with the reversible insertion of one Na at 2.55 V vs Na + /Na 0. 50 Keywords: sodium iron phosphate; marićite; sodium-ion batteries; oxidative decomposition; 51 NASICON 52 53 5

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