Fabrication Of Electrodes For Batteries Research Articles

Visualization of Porous Composite Battery Electrode Fabrication Dynamics for Different Formulations and Conditions Using Hard X-ray Microradiography.

Porous composite battery electrode performance is influenced by a large number of manufacturing decisions. While it is common to evaluate only finished electrodes when making process adjustments, one must then make inferences about the fabrication process dynamics from static results, which makes process optimization very costly and time-consuming. To get information about the dynamics of the manufacturing processes of these composites, we have built a miniature coating and drying apparatus capable of fabricating lab-scale electrode laminates while operating within an X-ray beamline hutch. Using this tool, we have collected the first radiography image sequences of lab-scale battery electrode coatings in profile, taken throughout drying processes conducted under industrially relevant conditions. To assist with interpretation of these image sequences, we developed an automated image analysis program. Here, we discuss our observations of battery electrode slurry samples, including stratification and long-term fluid flow, and their relevance to composite electrode manufacturing.

(Invited) Impact of Binder Selection in Advanced Lithium Battery Electrode Fabrication and Performance

Polymer based binder plays an important role in electrode structures for varies energy storage systems such as battery and capacitor. In conventional wet coating process for battery electrode fabrication process, the polymer binders are mixed with the active material and conductive additives to form the slurry for the coating. The binders provide both physical and chemical supporting to the overall electrode structure, in addition to the basic “gluing” function. In recent years, a lot of aqueous soluble polymers were introduced in lithium-ion battery study working as alternative of traditional PVDF binder. The application of aqueous based polymer binder covers graphite, silicon, metal oxide, and even sulfur electrode fabrication. In this talk we will present some of our recent study on selected polymer binders in certain chemistry, such as Li-S system. We will reveal the difference in both physical and chemical properties of the selected binders, as well as the impact on the overall electrochemical performance. We will also discuss the binder selection and challenges from manufacturing point of view.

Ultrahigh loading dry-process for solvent-free lithium-ion battery electrode fabrication

The current lithium-ion battery (LIB) electrode fabrication process relies heavily on the wet coating process, which uses the environmentally harmful and toxic N-methyl-2-pyrrolidone (NMP) solvent. In addition to being unsustainable, the use of this expensive organic solvent substantially increases the cost of battery production, as it needs to be dried and recycled throughout the manufacturing process. Herein, we report an industrially viable and sustainable dry press-coating process that uses the combination of multiwalled carbon nanotubes (MWNTs) and polyvinylidene fluoride (PVDF) as a dry powder composite and etched Al foil as a current collector. Notably, the mechanical strength and performance of the fabricated LiNi0.7Co0.1Mn0.2O2 (NCM712) dry press-coated electrodes (DPCEs) far exceed those of conventional slurry-coated electrodes (SCEs) and give rise to high loading (100 mg cm−2, 17.6 mAh cm−2) with impressive specific energy and volumetric energy density of 360 Wh kg−1 and 701 Wh L−1, respectively.

A Review of Dispersion Film Drying Research

Abstract Dispersion drying is an essential step in an enormous number of research and industry fields, including self-assembly, membrane fabrication, printing, battery electrode fabrication, painting, and large-scale solar cell fabrication. The drying process of dispersion directly influences the structure and properties of the resulting dried film. Thus, it is important to investigate the underlying physics of dispersion drying and the effects of different drying parameters. This article reviews modeling studies of coating drying processes, along with corresponding experimental observations. We have divided drying processes into two conceptual stages. In the first drying stage, liquid evaporation, particle sedimentation, and Brownian motion compete and affect the particle distribution during drying and thus in the final film structure. We have included a comprehensive discussion of the influences of drying parameters, such as evaporation rate, particle sizes, and temperature, on the above competition and the resulting film structure. A drying regime map describing where different drying phenomena dominate was formulated based on the literature. We also extended our discussion to the practical applications of battery slurry drying an essential step in conventional battery electrode manufacturing. In the second drying stage, the physics of porous drying and crack formation are reviewed. This review aims to provide a comprehensive understanding of dispersion drying mechanisms and to provide guidance in the design of film products with favorable structures and properties for targeted practical applications.

Thick Composite Lithium Ion Battery Electrodes Using Honeycomb-Patterned Carbon Nanotube Forests on Metal Foils

The growing demand for electric vehicles and portable devices has brought significant attention to the scalability, recyclability, and economics of both traditional and emerging battery technologies. Lithium-ion batteries (LIB) are approaching their theoretical energy density yet remain the most widespread and promising technology for the next 5-10 years, as alternative (e.g., Li-metal) chemistries and solid-state architectures are still in relatively early stages of commercial scale-up. An alternative route to improve LIB performance and therefore increase energy density, is to redesign the cell geometry to incorporate thick electrodes. Batteries with thick planar (2D) electrodes suffer from power limitations and capacity loss due to increased Li-ion diffusion distances and tortuosity. 3D electrode designs compensate for this weakness by providing micro-scale channels within the electrode to enable rapid charge transport.Prototype LIBs using 3D electrodes have been fabricated using a wide variety of laboratory techniques (e.g., lithography, imprinting, direct-ink writing), which have afforded study of diverse geometries (e.g., pillar arrays, lattices, interpenetrating structures) and active materials (e.g., Si, Sn, carbon-based, lithium transition metal oxides). However, these methods do not have requisite scalability or compatibility with industrial LIB processing techniques, which demand: (1) integration with cost-effective metal substrates as current collectors; (2) compatibility with commodity anode/cathode materials and electrolytes; and (3) high-rate continuous production and cell assembly. Moreover, the materials used in 3D electrodes must be mechanically robust, electrically conductive, patterned at the microscale level, and have sufficient porosity to accommodate expansion and contraction upon charging and discharging.We are developing thick 3D “honeycomb” battery electrodes using patterned, vertically aligned carbon nanotubes (VA-CNTs) as current collectors. CNTs are widely known to have high thermal and electrical conductivities, and to be mechanically durable. VA-CNTs (“forests”) form by self-organization of CNTs during chemical vapor deposition (CVD) on substrates using common hydrocarbon sources (e.g., C2H2, C2H4). However, well-established CNT growth techniques utilize rigid non-conductive substrates, such as silicon wafers, necessitating an additional transfer step to a suitable substrate. Recently, we translated these insights from CNT growth on silicon wafer substrates to thin metal foils (Cu) suitable for battery electrode fabrication, using optimized in-furnace moisture conditions, and a thin-film interface that forms high-density nanoparticles upon annealing, and prevents diffusion of Cu that is known to poison CNT growth. The resulting CNT forests can reach up to 500 μm thickness and can be patterned to have regular hole arrays with feature sizes as small as ~5 μm.Thick composite electrodes are then created by coating CNT forests with Si thin films by CVD. The inherent nanoporosity of the CNT forests (>95%) allows for precursor diffusion into the entirety of the forest cross-section. The CVD conditions are tuned to create dense electrodes with tailored Si loading ranging from ~10 to ~90 at.%. Half-cells using monolithic and patterned Si-CNT electrodes (~200 μm tall), Li-metal foil and a liquid electrolyte/separator combination are cycled over a range of currents, demonstrating electronic connection between the deposited Si and Cu foil via the aligned CNTs. At low currents (C/5) these electrodes demonstrate large gravimetric capacities, indicating the lithiation of CNTs beneath the deposited Si. We will also investigate cycling performance at high currents (>5C) and perform post-mortem characterization of the Si-CNT interface to study how the CNTs and their patterning govern the stability of the electrode. Future work will look to optimize electrode performance by manipulating the geometric parameters of the CNT forests and assess the economics of CNT-based electrode manufacturing at commercial scales.

Hard Carbons for Use as Electrodes in Li-S and Li-ion Batteries.

Activated hard carbons, obtained from the pyrolysis of various waste biomasses, were prepared and characterized for use as the active material for the fabrication of battery electrodes. The preparation consisted of a pyrolysis process, followed by an activation with KOH and a further high-temperature thermal process. TG and DTA were used to discriminate the steps of the activation process, while SEM, XRD, and Raman characterization were employed to evaluate the effects of activation. The activated carbons were tested as electrodes in lithium-sulfur and lithium-ion batteries. The carbonaceous materials coming from cherry stones and walnut shells have proved to be particularly suitable as electrode components. When used as anodes in lithium-ion batteries, both carbons exhibited a high first cycle discharge capacity, which was not restored during the next charge. After the first two cycles, in which there was a marked loss of capacity, both electrodes showed good reversibility. When used as cathodes in lithium-sulfur batteries, both carbons exhibited good catalytic activity against the redox reaction involving sulfur species with good cycle stability and satisfactory Coulombic efficiency.

Holey Graphene–Enabled Solvent-Free Preparation of Ultrahigh Mass Loading Selenium Cathodes for High Areal Capacity Lithium–Selenium Batteries

Solvents and binders are typical requirements in conventional lithium ion battery electrode fabrication to enable intimate material mixing, mechanical robustness, and reproducibility. However, for high energy density conversion chemistry cathodes such as sulfur (S) and selenium (Se), the time-consuming solvent-based methods are proven unreliable to achieve high mass loading cathodes with sufficient quality. Here, we report a facile solvent-free and binder-free method to prepare high mass loading composite Se cathodes that is enabled by the use of holey graphene (hG) as a lightweight conductive scaffold. Holey graphene is a derivative of graphene and can be dry-pressed into robust discs by itself. It can also serve as a matrix to host materials such as Se for composite disc preparation in a mix-and-press process free of solvent and binder. The method allows the preparation of ultrahigh Se content cathodes (up to 90 wt% Se) and ultrahigh Se mass loading (up to 15.6 mg cm−2 in this work). These cathodes exhibit excellent Se utilization, high areal capacity (up to 9 mAh cm−2), and good rate performance. The dry-press approach also allows for the preparation of a layered composite cathode architecture, where a thin hG layer is inserted between the composite and the current collector to improve the electrical contact. A solvent-free approach is also used to prepare hG-based hybrids with metal sulfides to be incorporated into a composite cathode to help entrap soluble polyselenide intermediates. The hybrid material is compatible with the solvent-free mix-and-press electrode fabrication approach and shows promise in improving the Se retention. While further improvements are still required, this work demonstrates the outstanding potential of using this facile, solvent-free approach enabled by hG for fabrication of high-performance, high mass loading conversion chemistry cathodes.

Full Utilization of Lithium Trivandate (Li1.1V3O8) in Thick Porous Electrodes with High Rate Capacity upon Extended Cycling Elucidated Via Operando Energy Dispersive X-Ray Diffraction

Newer, more demanding energy storage systems require high energy density along with high power and fast charge rates. Conventional battery electrode fabrication techniques are often limited by how much active material they can hold in the case of slurry-cast electrodes and how much of the electrode can be utilized in the case of dense pelletized electrodes. Thick porous electrode fabrication techniques have been developed as a way to obtain a higher active mass loading and an architecture which enables ionic and electronic transport. The homogeneity of the phase distribution of lithiated LVO in thick (∼500 μm) porous electrodes (TPEs) designed to facilitate both ion and electron transport was determined using synchrotron-based operando energy dispersive X-ray diffraction (EDXRD). Probing 3 positions in the TPE while cycling at a fast rate of 1C revealed a homogeneous phase transition across the thickness of the electrode at the 1st and 95th cycles. Continuum modelling indicated homogenous lithiation across the electrode upon discharge at 1C consistent with the EDXRD results and ascribed decreasing accessible active material to be the cause of loss in delivered capacity between the 1st and 95th cycles. The model was supported by the observation of significant particle fracture by SEM consistent with loss of electrical contact. The absence of the beta phase peaks in the EDXRD over extended cycling are consistent with electrochemical accessibility of only part of the active material. Overall, the combination of operando EDXRD, continuum modeling, and ex situ measurements enabled a deeper understanding of lithium vanadium oxide transport properties under high rate extended cycling within a thick highly porous electrode architecture.

Discrete Element Method Simulation of Electrode Calendering and Its Impact on Electrochemical Performance

Lithium-ion battery (LIB) manufacturing optimization is crucial to reduce its CO2 fingerprint and cost, while improving their electrochemical performance. The latter is particularly challenging, due to the several parameters involved in LIB manufacturing and in their non-linear relationships. The aim of the ERC founded ARTISTIC project1,2 is to develop computational tools able to capture the effect of the manufacturing process on final electrode’s properties through multiscale modelling3–8 and machine learning (ML).9,10 We present here11,12 our latest work, applying discrete 3D (x,y,z) and continuum 4D (x,y,z and time) models to capture the effect of calendaring on LiNi0.33Mn0.33Co0.33O2–based cathodes. Our methodology is based on an experimentally validated Discrete Element Method model, which considers explicitly both active material (AM) and carbon-binder domain (CBD). The latter introduces important novelties respect the state of the art, such as: (i) the utilization of un-calendered electrode mesostructures resulting from experimentally validated simulations of the previous fabrication steps (slurry formulation and drying) in which the spatial distribution and interactions between AM and CBD particles are considered explicitly.3–5 (ii) the model validation through simultaneous comparison of experimental and simulated micro-indentation and porosity vs. calendering pressure curves. The resulting calendered electrodes were analyzed in terms of pore size distribution, tortuosity and particles arrangement. In addition, the evolution of the electrodes’ macroscopic electrochemical behavior (galvanostatic discharge curve and electrochemical impedance spectroscopy) upon the degree of calendering was discussed, offering added insights into the links between calendering pressure, electrode mesostructure and its electrochemical performance. References (1) https://www.u-picardie.fr/erc-artistic/.(2) https://www.u-picardie.fr/erc-artistic/computational-portal/.(3) Ngandjong, A. C.; Rucci, A.; Maiza, M.; Shukla, G.; Vazquez-Arenas, J.; Franco, A. A. Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. J. Phys. Chem. Lett. 2017, 8 (23), 5966–5972. https://doi.org/10.1021/acs.jpclett.7b02647.(4) Rucci, A.; Ngandjong, A. C.; Primo, E. N.; Maiza, M.; Franco, A. A. Tracking Variabilities in the Simulation of Lithium Ion Battery Electrode Fabrication and Its Impact on Electrochemical Performance. Electrochim. Acta 2019, 312, 168–178. https://doi.org/https://doi.org/10.1016/j.electacta.2019.04.110.(5) Lombardo, T.; Hoock, J.; Primo, E.; Ngandjong, C.; Duquesnoy, M.; Franco, A. A. Accelerated Optimization Methods for Force-Field Parametrization in Battery Electrode Manufacturing Modeling. Batter. Supercaps 2020. https://doi.org/10.1002/batt.202000049.(6) Chouchane, M.; Rucci, A.; Lombardo, T.; Ngandjong C., A.; Franco, A. A. Lithium Ion Battery Electrodes Predicted from Manufacturing Simulations: Assessing the Impact of the Carbon-Binder Spatial Location on the Electrochemical Performance. J. Power Sources 2019. https://doi.org/https://doi.org/10.1016/j.jpowsour.2019.227285.(7) Chouchane, M.; Primo, E. N.; Franco, A. A. Mesoscale Effects in the Extraction of the Solid-State Lithium Diffusion Coefficient Values of Battery Active Materials: Physical Insights from 3D Modeling. J. Phys. Chem. Lett. 2020, 11 (7), 2775–2780. https://doi.org/10.1021/acs.jpclett.0c00517.(8) Shodiev, A.; Primo, E. N.; Chouchane, M.; Lombardo, T.; Ngandjong, A. C.; Rucci, A.; Franco, A. A. 4D-Resolved Physical Model for Electrochemical Impedance Spectroscopy of Li(Ni1-x-YMnxCoy)O2-Based Cathodes in Symmetric Cells: Consequences in Tortuosity Calculations. J. Power Sources 2020, 454, 227871. https://doi.org/10.1016/j.jpowsour.2020.227871.(9) Cunha, R. P.; Lombardo, T.; Primo, E. N.; Franco, A. A. Artificial Intelligence Investigation of NMC Cathode Manufacturing Parameters Interdependencies. Batter. Supercaps 2020, 3 (1), 60–67. https://doi.org/doi:10.1002/batt.201900135.(10) Duquesnoy, M.; Lombardo, T.; Chouchane, M.; Primo, E. N. Data-Driven Assessment of Electrode Calendering Process by Combining Experimental Results , in Silico Mesostructures Generation and Machine Learning. J. Power Sources 2020, 480, 229103. https://doi.org/10.1016/j.jpowsour.2020.229103.(11) Ngandjong, A.; Lombardo, T.; Primo, E.; Chouchane, M.; Shodiev, A.; Arcelus, O.; Franco, A. A. Investigating Electrode Calendering and Its Impact on Electrochemical Performance by Means of a New Discrete Element Method Model: Towards a Digital Twin of Li-Ion Battery Manufacturing. ChemRxiv 2020, 1–40.(12) Ngandjong, A.; Lombardo, T.; Primo, E.; Chouchane, M.; Shodiev, A.; Arcelus, O.; Franco, A. A. Investigating Electrode Calendering and Its Impact on Electrochemical Performance by Means of a New Discrete Element Method Model: Towards a Digital Twin of Li-Ion Battery Manufacturing. J. Power Sources 2020, accepted .

Battery-on-Separator: A platform technology for arbitrary-shaped lithium ion batteries for high energy density storage

Arbitrary-shaped batteries with high energy densities are strongly desired for weight- and power-sensitive applications to meet various layout and function demands. Conventional battery electrode fabrication protocol requires a relatively thick metal foil (9–15 μm) to provide sufficient mechanical strength for slurry coating, leading to high occupancy of inactive components. Besides, conventional battery assembly methods result in limited battery layouts, which is difficult for well-fitting complex-shaped electronics. To overcome these limitations, developing novel battery fabrication technologies is critically urgent and important. Herein, we report a scalable method to fabricate arbitrary-shaped lithium-ion batteries with ultra-thin current collectors. Built on a commercial polypropylene separator, an all-in-one structured lithium ion battery is fabricated by integrating active material layers and ultra-thin metal film current collectors (optimally 2-μm-thick) through stencil printing and magnetron sputtering methods. By reducing the thickness of current collectors down to 2 μm, the energy density of a LiFePO4//Li4Ti5O12 full cell can be increased by 16%–64% based on the designed areal capacities between 1 mAh cm−2 to 3 mAh cm−2. Such battery fabrication method can effectively realize the shape diversity of electrodes, thereupon enabling the seamless integration of arbitrary-shaped batteries into versatile potable electronics to improve their space utilization.

Conducting Polymer Composites As Multifunctional Electrode Matrices for Lithium-Ion Batteries

The rising number of lithium-ion battery cells fabricated to power electric vehicles has raised concerns about the environmental impacts of battery electrode fabrication process. Typically, N-Methyl-2-pyrrolidone (NMP) solvent is used to blend active materials and electrode matrices, which are normally polyvinylidene fluoride/carbon-black (PVDF/C) mixtures. The use of NMP solvent, however, requires extensive energy for electrode drying and toxic solvent recovery. In addition, the PVDF/C electrode matrix offers weak interactions with active materials, which results in poor morphological integrity and rapid capacity fading, especially for high-volume-change electrode materials. Using water-processable binders such as carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) has been proven to enable a greener electrode-casting process as well as improve electrode performance. However, the electrical conductivity of these electrodes relies mainly on carbon additives, which are subjected to agglomeration and volumetric-capacity reduction. In this study, new electrode matrices are developed from in situ polymerized polypyrrole:carboxymethyl-cellulose (PPy:CMC) composites with water-processable and electrical-conductive features. By forming a composite structure in which CMC acts as an anionic dopant for PPy conducting polymer, the PPy:CMC composites show good electrical conductivity, allowing them to be used as mono-component electrode matrices. As a result, carbon-additive-free LiCoO2/PPy:CMC electrodes can cycle at different C-rate. More importantly, the PPy:CMC composites enable aqueous slurry electrode casting, addressing the environmental pollution associated with NMP solvent utilization. The study introduces another potential application of conducting polymer composites in Li-ion batteries.Keywords: aqueous electrode casting, conducting polymers, polypyrrole.

Designs of Experiments to Optimize Li-Ion Batteries

Studies pinpointed the limitation of power-related performance for Li-ion batteries to the microstructure of each electrode.1, 2 This random arrangement of the active material (AM) and carbon filling particles bound by a polymer is typically characterized through physical values such as tortuosity, porosity and Mac Mullin Number.3 There is nonetheless no consensus on what the best formulation is for a given set of electrode components.The relationship between microstructure and performance is investigated by planning and analyzing a Design of Experiments based on a Complex Mixture Design. Thirty different formulations were characterized where Li4Ti5O12 was the AM, and carbon black and carbon nanofibers were conductive fillers. As for the binder, two were studied: polyvinylidene fluoride and a fluorine-free thermoplastic elastomer.4 All other factors, e.g. rheology or experimenter bias, were closely monitored and finely controlled to remain identical for all samples.Electrochemical performance were studied at low, medium and high charging speeds to account for different limitations of full capacity retention. Statistical analysis showed clear correlations between the formulation and the electrodes’ capacity with very high descriptive statistics, e.g. R2. Lastly, strong correlations were found between capacity and microstructure, strengthening further the trust in the empirical equations. These robust models helped choosing optimal fluorine-free formulations that surpassed even the highest performing previous electrodes. 1. Vasileiadis, A.; Klerk, N. J. J. d.; Smith, R. B.; Ganapathy, S.; Harks, P. P. R. M. L.; Bazant, M. Z.; Wagemaker, M., Toward Optimal Performance and In‐Depth Understanding of Spinel Li4Ti5O12 Electrodes through Phase Field Modeling. Advanced Functional Materials 2018, 0 (0), 1705992.2. Ngandjong, A. C.; Rucci, A.; Maiza, M.; Shukla, G.; Vazquez-Arenas, J.; Franco, A. A., Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. The Journal of Physical Chemistry Letters 2017, 8 (23), 5966-5972.3. Landesfeind, J.; Hattendorff, J.; Ehrl, A.; Wall, W. A.; Gasteiger, H. A., Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy. Journal of The Electrochemical Society 2016, 163 (7), A1373-A1387.4. Rynne, O.; Lepage, D.; Aymé-Perrot, D.; Rochefort, D.; Dollé, M., Application of a Commercially-Available Fluorine-Free Thermoplastic Elastomer as a Binder for High-Power Li-Ion Battery Electrodes. Journal of The Electrochemical Society 2019, 166 (6), A1140-A1146.With this presentation, we want to show the versatility and power of Designs of Experiments to the community, whether for electrode formulation or new material synthesis, as the input parameters can be easily interchangeable. Figure 1

Electrophoretically co-deposited Li4Ti5O12/reduced graphene oxide nanolayered composites for high-performance battery application

Achieving aggregation-free nanocomposites is a challenge for the conventional casting process in Li-ion battery electrode fabrication, which leads to inhomogeneous dispersion of active and conductive components – a property which further accelerates, or triggers, battery degradation. This becomes even more challenging when using 2D nanomaterials. In this paper, electrophoretic deposition (EPD) is used to fabricate nanolayered composite anodes composed of spinel lithium titanate (LTO) and reduced graphene oxide (rGO). First, the electrode material precursors, 2D-lithium titanate hydrate (LTH) and graphene oxide nanosheets, are formulated into a stable colloidal suspension and electrophoretically co-deposited (EPD) onto copper substrate. Subsequently, the binder-free deposits are annealed at 600 ​°C in a 5% hydrogen environment for 6 ​h to induce in-situ topotactic transformation of the precursors into LTO/rGO nanolayered composites. Comparing to their PVDF-built electrodes, the EPD nanolayered composites exhibit robust electrochemical performance in terms of power capability, cyclability and impedance control. This performance enhancement is due to a well-established graphene oxide-based percolation network for both electronic and ionic conduction engineered with the help of EPD. Therefore, the local deep discharge to lower state-of-charges is avoided, hence avoiding the serious capacity fade from which nano-LTO suffers. Through this research, EPD casting technology presents itself as superior mesoscale construction strategy for nanostructured LIB electrodes.

(Invited) Accelerating Optimization of Lithium Ion Battery Manufacturing Via Multiscale Computations

Electrochemical performance and lifetime of Lithium Ion Battery (LIB) composite electrodes strongly depend on their manufacturing parameters. Such parameters include the slurry formulation (i.e. the chemistry and amount of active material, carbon, binder and solvent), the temperature used to evaporate the solvent, the pressure applied during the electrode calendering and the time for the electrolyte impregnation. Within the perspective of developing more efficient LIBs at minimal R&D cost, it is important to develop robust tools able to predict the influence of manufacturing parameters on the electrodes mesostructure and the overall cell performance. In this keynote, i discuss the latest research progress in this sense within the ARTISTIC project, funded by the European Research Council (ERC). This project aims at developing and demonstrating a multiscale computational platform able to simulate the LIB manufacturing process and to predict optimal manufacturing parameters of LIBs responding to specific targets (energy density, etc.). Coarse Grained Molecular Dynamics, Discrete Element Method, Lattice Boltzmann and Continuum computational models are combined with deep learning algorithms to reach this objective. Examples of applications of this platform for NMC and graphite-based electrodes are discussed, in strong link with in house experimental characterizations. Physicochemical mechanisms leading to the composite electrode self-organization are discussed and guidelines towards the optimization of the multiple process steps are presented. At the end of the lecture, an experience using an in house Virtual Reality tool, to assess the manufacturing modeling results, will be proposed to the attendees. [1] ARTISTIC project (European Research Council Consolidator Grant #772873): https://www.u-picardie.fr/erc-artistic/[2] Franco, A. A., Rucci, A., Brandell, D., Frayret, C., Gaberscek, M., Jankowski, P., & Johansson, P. (2019). Boosting Rechargeable Batteries R&D by Multiscale Modeling: Myth or Reality?. Chemical Reviews. DOI: 10.1021/acs.chemrev.8b00239 [3] Rucci, A., Ngandjong, A. C., Primo, E., Maiza, M., & Franco, A.A., submitted (2019). [4] Ngandjong, A. C., Rucci, A., Maiza, M., Shukla, G., Vazquez-Arenas, J., & Franco, A. A. (2017). Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. The journal of physical chemistry letters, 8(23), 5966-5972. Figure 1

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

Tracking variabilities in the simulation of Lithium Ion Battery electrode fabrication and its impact on electrochemical performance

In this paper we report a comprehensive analysis and tracking of the variabilities associated to multiscale simulations coupling a Coarse Gained Molecular Dynamics (CGMD) model of Lithium Ion Battery (LIB) electrodes fabrication with a 3D-resolved performance model at the cell scale. We quantify the impact on the final electrode mesostructure of the initial conditions in the CGMD simulations in terms of initial random distribution in the slurry of the active material and carbon binder domain particles (CBD). This study is carried out with a batch of simulations at different slurry active material/CBD compositions. Results show that for each electrode composition there is a statistical dispersion in the predicted cell performance curves, in agreement with in house experimental results. Furthermore, in house experiments revealed a different correlation regime depending on the C-rate at which the cathode is operating. The proposed methodology and findings allows us to pave the way towards the design of reliable approaches to control the variables correlations in the multiscale modeling of electrodes fabrication and its impact on LIB performance.

Multiscale Simulation of the Fabrication Process of Lithium Ion Battery Electrodes

I present here our ongoing efforts at developing and demonstrating a multiscale computational framework devoted to rationalize the formulation of lithium ion battery composite electrodes containing next-generation material chemistries. The framework is being established through the combination of discrete particle (Coarse Grained Molecular Dynamics) and continuum mathematical models within a multiparadigm and multiscale approach mimicking the different steps along the electrode fabrication process, i.e. slurry preparation, drying and calendering. In strong complement to dedicated experimental characterizations, the theoretical framework provides fundamental insights on self-organization mechanisms of material mixtures in slurries and on the relationship between the materials properties, the electrode composition (formulation), the fabrication process layout and the arising electrode microstructure. Practical application of the framework to lithium ion battery electrodes based on NMC materials is presented. Finally, I discuss its potential to provide insights leading to proposals of new and highly efficient industrial techniques for the fabrication of cheaper and reliable next-generation lithium ion battery electrodes for a wide spectrum of applications, including Electric Transportation. References ERC Project "ARTISTIC" (Advanced and Reusable Theory for the In Silico- optimization of composite electrode fabrication processes for rechargeable battery Technologies with Innovative Chemistries) (European Research Council funded project, grant agreement No. 772873). A. Ngandjong, A. Rucci, M. Maiza, G. Shukla, J. Vazquez-Arenas, A.A. Franco, "Towards A Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process With Performance At The Cell Level", J. Phys. Chem. Letters, 8 (23) (2017) 5966. A.A. Franco, M.L. Doublet, W. Bessler, Eds., book title: "Multiscale Modeling and Numerical Simulation of Electrochemical Devices for Energy Conversion and Storage", Springer, UK (2015).

A Flexible Multiscale Simulation Platform of Rechargeable Batteries

We present here our most recent progress towards the development of an in house multiscale computational platform able to simulate electrochemical and transport mechanisms at multiple spatio-temporal scales in a wide diversity of rechargeable battery technologies. The platform combines discrete models based on kinetic Monte Carlo and Coarse Grained Molecular Dynamics with pseudo-2D and 3D-resolved continuum models within sequential and iterative coupled computational workflows. The flexibility of the platform is discussed within the context of the following engineering-oriented studies: - impact of the electrodes texture on lithium ion battery cycling (case of graphite and NMC-based electrodes). The role of the electrodes composition hererogeneities (carbon/binder/active material) and anisotropies on lithium transport in the electrolyte and in the active material are in particular investigated; - impact of the positive electrode texture on the cyclability of lithium sulfur batteries. Particular attention is paid here on the Li2S deposition and decomposition dynamics as function of the polysulfides elementary reactions, electrolyte volume and initial carbon/sulfur ratio; - impact of carbon-based positive electrode textures on the cyclability of lithium oxygen batteries. Particular attention is paid here on the relationships between Li2O2 particle size distributions and carbon pore size distirbution in the effectiveness of electrochemical reactions; - impact of the electrodes composition and C-rate on the cyclability of slurry-based redox flow batteries (case of Si/C suspensions). Practical implications from these studies at the engineering level in terms of optimal electrode textures (porosity, pore size distribution, tortuosities) are discussed in comparison with experimental data. The strong interest of combining this platform with post-processing tools based on Virtual and Augmented Reality technologies is finally discussed, based on recent sucessful experiences with students in Amiens. References A. Torayev, A. Rucci, P. Magusin, A. Demortière, V. De Andrade, C. Grey, C. Merlet, A.A.Franco, "Stochasticity of Pores Interconnectivity in Lithium Oxygen Batteries and Its Impact on the Variations in Electrochemical Performance ", J. Phys. Chem. Letters, 9 (4) (2018) 791. A. Ngandjong, A. Rucci, M. Maiza, G. Shukla, J. Vazquez-Arenas, A.A. Franco, "Towards A Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process With Performance At The Cell Level", J. Phys. Chem. Letters, 8 (23) (2017) 5966. Y. Yin, A. Torayev, C. Gaya, Y. Mammeri, A.A. Franco, "Linking the Performances of Li-O2 Batteries to Discharge Rate, Electrode and Electrolyte Properties through the Nucleation Mechanism of Li2O2", Journal of Physical Chemistry C, 121 (36) (2017) 19577. G. Shukla, D. Del Olmo Diaz, V. Thangavel, A.A. Franco, "Self-organization of Electroactive Suspensions in Discharging Slurry Batteries: A Mesoscale Modeling Investigation", ACS Applied Materials and Interfaces, 9(21) (2017) 17882. V. Thangavel, K.H. Xue, Y. Mammeri, M.A. Quiroga, C. Guery, A. Mastouri, P. Johansson, M. Morcrette, A.A. Franco, "A microstructurally resolved model for Li-S batteries assessing the impact of the cathode design on the discharge performance", J. Electrochem. Soc., 163 (13) (2016) A2817.

Microstructure-Controlled 3D Electrodes for Lithium-Ion Batteries

A new battery electrode fabrication process in which the micro/macroscale structures are simultaneously controlled is proposed. In the processing, an electric field controls the microscale particle network in an electrode, while an additive manufacturing controls the macroscale three-dimensional geometry of the electrode. This synergistic control of micro-/macro-structures is a novel concept in energy material processing, and has considerable potential for providing unprecedented control of electrode structures with enhancing performance. Electrochemical tests have shown that these new electrodes exhibit superior performance in their specific capacity, areal capacity, and life cycle.

Electrochemical Fabrication of Freestanding Thin-Film Electrodes for Batteries and Catalysis

In this work, a freestanding and binder-free NiS2/FeS holey film is developed using a facile and scalable electrochemical route . Both experimental study and computational investigation were performed to have an insightful understanding of the charge storage mechanism of this advanced energy material for LSBs. Such freestanding NiS2/FeS holey film provides unique merits for LSBs: i) Porous structure of holey film enables a large surface area for an enhanced ion/mass diffusion and reduced volume expansion; ii) The binder-free electrode combines the current collector (residual NiFe alloy) and active materials (sulfides) together, improving electron transport; iii) Sulfides are more stable as active materials than sulfur, showing only a small capacity decay while retaining high cyclability performance. A high volumetric capacity of 580 mAh cm-3 and a long-term stability over 1000 discharge-charge cycles were, therefore, achieved due to these merits.