Reactive Molecular Dynamics Simulations Of Lithium Secondary Batteries Interfaces And Electrodes

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Reactive Molecular Dynamics Simulations of Lithium Secondary Batteries - Interfaces and Electrodes

Author : Md Mahbubul Islam
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (971 download)

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Book Synopsis Reactive Molecular Dynamics Simulations of Lithium Secondary Batteries - Interfaces and Electrodes by : Md Mahbubul Islam

Download or read book Reactive Molecular Dynamics Simulations of Lithium Secondary Batteries - Interfaces and Electrodes written by Md Mahbubul Islam and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last two decades, lithium-based batteries have revolutionized the energy storage technologies. Li-ion batteries have found widespread use in portable electronics and electric vehicle applications. However, a detailed understanding of the battery chemistry, especially the formation of a solid electrolyte interphase (SEI)a thin passivation layer which is generated during the first charge cycle due to the reduction of electrolytesis still elusive. The mass scale commercialization of electric vehicles requires the storage capacity beyond the conventional Li-ion batteries, which spurred research interests towards Li-S technologies. Li-S batteries are attractive for their very high capacity and energy density, but their commercial application has been thwarted due to several critical limitations stemming from electrolyte dissociation chemistry and electrode material properties. To investigate the current issues associated with the Li-ion and Li-S batteries and to find possible countermeasures, we used both a newly developed computational tool eReaxFF and the standard ReaxFF reactive molecular dynamics simulations in the following research areas:1) We developed a computational method, eReaxFF, for simulating explicit electrons within the framework of the standard ReaxFF reactive force field method. We treat electrons explicitly in a pseudoclassical manner that enables simulation several orders of magnitude faster than quantum chemistry (QC) methods, while retaining the ReaxFF transferability. We describe in this thesis the fundamental concepts of the eReaxFF method, and the integration of the Atom-condensed Kohn-Sham DFT approximated to second order (ACKS2) charge calculation scheme into the eReaxFF. We trained our force field to capture electron affinities (EA) of various species. As a proof-of-principle, we performed a set of molecular dynamics (MD) simulations with an explicit electron model for representative hydrocarbon radicals. We establish a good qualitative agreement of EAs of various species with experimental data, and MD simulations with eReaxFF agree well with the corresponding Ehrenfest dynamics simulations. The standard ReaxFF parameters available in literature are transferrable to the eReaxFF method. The computationally economic eReaxFF method will be a useful tool for studying large-scale chemical and physical systems with explicit electrons as an alternative to computationally demanding QC methods. 2) A detailed understanding of the mechanism of the formation of SEI is crucial for designing high capacity and longer lifecycle lithium-ion batteries. The anode side SEI is primarily comprised of the reductive dissociation products of the electrolyte molecules. Any accurate computational method to study the reductive decomposition mechanism of electrolyte molecules is required to possess an explicit electronic degree of freedom. In this study, we employed our newly developed eReaxFF method to investigate the major reduction reaction pathways of SEI formation with ethylene carbonate (EC) based electrolytes. In the eReaxFF method, a pseudo-classical treatment of electrons provides the capability to simulate explicit electrons in a complex reactive environment. Our eReaxFF predicted simulation results of the EC decomposition reactions are in good agreement with the quantum chemistry data available in literature. Our MD simulations capture the mechanism of the reduction of the EC molecule due to the electron transfer from lithium, ring opening of the EC to generate EC-/Li+ radicals, and subsequent radical termination reactions. Our results indicate that the eReaxFF method is a useful tool for large-scale simulations to describe redox reactions occurring at electrode-electrolyte interfaces where quantum chemistry based methods are not viable due to their high computational requirement.3) Li-S batteries still suffer several formidable performance degradation issues that impede their commercial applications. The lithium negative electrode yields high anodic capacity, but it causes dendrite formation and raises safety concerns. Furthermore, the high reactivity of lithium is accountable for electrolyte decomposition. To investigate these issues and possible countermeasures, we used ReaxFF reactive molecular dynamics simulations to elucidate anode-electrolyte interfacial chemistry and utilized an ex-situ anode surface treatment with Teflon coating. In this study, we employed Li/SWCNT (single-wall carbon nanotube) composite anode instead of lithium metal and tetra (ethylene glycol) dimethyl ether (TEGDME) as electrolyte. We find that at a lithium rich environment of the anode-electrolyte interface, electrolyte dissociates and generates ethylene gas as a major reaction product, while utilization of Teflon layer suppresses the lithium reactivity and reduces electrolyte decomposition. Lithium discharge from the negative electrode is an exothermic event that creates local hot spots at the interfacial region and expedites electrolyte dissociation reaction kinetics. Usage of Teflon dampens initial heat flow and effectively reduces lithium reactivity with the electrolyte. 4) Sulfur cathodes of Li-S batteries undergo a noticeable volume variation upon cycling, which induces stress. In spite of intensive investigation of the electrochemical behavior of the lithiated sulfur compounds, their mechanical properties are not very well understood. In order to fill this gap, we developed a ReaxFF interatomic potential to describe Li-S interactions and performed MD simulations to study the structural, mechanical, and kinetic behavior of the amorphous lithiated sulfur (a-LixS) compounds. We examined the effect of lithiation on material properties such as ultimate strength, yield strength, and Youngs modulus. Our results suggest that with increasing lithium content, the strength of lithiated sulfur compounds improves, although this increment is not linear with the lithiation. The dependence of the mechanical properties and failure behavior on the loading rate of the amorphous lithiated sulfur compositions was also studied. The diffusion coefficients of both lithium and sulfur were computed for the a-LixS system at various stages of Li-loading. A Grand canonical Monte Carlo (GCMC) scheme was used to calculate the open circuit voltage (OCV) profile during cell discharge. The calculated OCV is consistent with prior experimental results. Our ReaxFF potentials also reproduced experimentally observed volume expansion of a-LixS phases upon lithiation. The Li-S binary phase diagram was constructed using genetic algorithm based tools. These simulation results provide insight into the behavior of sulfur-based cathode materials that are needed for developing high-performance lithium-sulfur batteries.

Development and Application of a ReaxFF Reactive Force Field for Solid Electrolyte Interphase Study in Silicon Based Li-ion Batteries

Download Development and Application of a ReaxFF Reactive Force Field for Solid Electrolyte Interphase Study in Silicon Based Li-ion Batteries PDF Online Free

Author : Mahdi Khajeh Talkhoncheh
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (144 download)

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Book Synopsis Development and Application of a ReaxFF Reactive Force Field for Solid Electrolyte Interphase Study in Silicon Based Li-ion Batteries by : Mahdi Khajeh Talkhoncheh

Download or read book Development and Application of a ReaxFF Reactive Force Field for Solid Electrolyte Interphase Study in Silicon Based Li-ion Batteries written by Mahdi Khajeh Talkhoncheh and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The amount of energy required to satisfy the demands of the human population may not be able to be supplied solely by fossil fuels as the world population continues to rise and the supply of fossil fuels starts to decline. Lithium-ion batteries (LIBs), since being suggested as commercialized energy storage systems by Sony company in the 1990s, have been considered an important device in alternative energy solutions owing to their high energy density, wide working voltage, long cycling life, and low self-discharge rate. Improvement of the performance of these high energy chemical systems is directly linked to the understanding and improving the complex physical and chemical phenomena and exchanges that take place at their different interfaces. Surfaces or interfaces, which means structures built between dissimilar media such as liquids and solids, and interphases, which means structures formed within these dissimilar media, present significant challenges for their study and understanding since these are the regions where myriad events such as electron transfer, ion transfer and migration, reactions, and solvation/desolvation processes occur and significantly alter their configuration. A detailed understanding of battery chemistry, especially the formation of a solid electrolyte interphase (SEI)--a thin passivation layer which is generated during the first charge cycle due to the reduction of electrolytes--is still elusive. It is well known that the SEI has a strong influence on the battery performance characteristics, such as irreversible capacity, safety, and cycle life, when the SEI is a thin layer between the liquid electrolytes and anode surfaces formed by the electrochemical reductive decomposition reaction of the electrolyte during the initial few cycles. A stable SEI with full surface coverage over the electrode is important for achieving optimal electrochemical performances of Li-ion batteries. Understanding the SEI is quite challenging due to its complicated and amorphous structure. In order to investigate the physical and chemical interactions at the interfaces of energy storage devices such as Li-ion batteries a, we used ReaxFF reactive molecular dynamics simulations in the following two research areas: 1. In the last decade silicon has attracted significant attention as a potential next generation anode material for Li-ion batteries (LIBs) due to its high theoretical specific capacity (3579 mAh/g (Li15Si4)) compared to that of the commonly used graphite (372 mAh/g). However, despite the apparent attractiveness of Si in view of its application in LIBs, it is known to suffer from severe degradation problems which lead to performance losses of Si-based anodes, and the electrochemical outcome of the degradation is well documented in the literature: rapid capacity fading of the anode accompanied by the increased internal resistance of the cell. Full utilization of silicon's potential as an anode material is thus prevented by incomplete understanding of the degradation mechanisms and the resulting inability to implement effective mitigation tactics. To study the Si anode degradation at the anode/electrolyte interface, we have developed a ReaxFF reactive force field simulation protocol. In this protocol, a delithiation algorithm is employed. This novel systematic delithiation algorithm helps to capture the effect of different delithiation rates, which plays an important role in the irreversible structural change of delithiated Si. Besides, the fundamental of degradation was investigated by analyzing the relationship between the depth of discharge and corresponding volume and structural changes at different rates. 2. The SEI (solid-electrolyte interphase) is important for protecting silicon anodes in batteries from losing both silicon and electrolyte through side reactions. A major issue with this technology is SEI breakdown caused by cracking in silicon particles. A strategy is presented for creating a self-sealing SEI that automatically covers and protects the cracked surface of silicon microparticle anodes by bonding an ion pair to the silicon surface. The cations in the bond prevent silicon-electrolyte reactions while the anions migrate to the cracked surface and decompose more easily than the electrolyte. The SEI formed in this way has a double layer structure with a high concentration of lithium fluoride in the inner layer. To study the electrode electrolyte reactions at the anode/electrolyte interface, we have developed ReaxFF reactive force field parameter sets to organic electrolyte species such as ethylene carbonate, N-methyl-N-propyl pyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI), LiPF6 salt and lithium-Silicon oxygen electrode. Density Functional Theory (DFT) data describing Li-associated initiation reactions for the organic electrolytes and bonding energies of Li-electrolyte structures were generated and added to ReaxFF training data and subsequently, we trained the ReaxFF parameters with the aim to find the optimal reproduction of the DFT data. This force field is capable of distinguishing Li interaction with electrolyte in presence of self-sealing layer. Moreover, these findings provide a new way to design a stable SEI at the highly dynamic electrode-electrolyte interface. In addition to this battery work, we also studied halogen interaction with platinum surfaces, a system that has received considerable attention in catalysis and semiconductor mannufacturing. These halogen gases are applied as platinum mobilizers in both deposition and corrosion or etching processes since PtCl4 adsorption from an electrolyte and subsequent reduction to metallic Pt clusters is an electrochemical pathway for obtaining highly dispersed, catalytically active Pt surfaces. A novel ReaxFF reactive force field has been developed to understand the size and shape-dependent properties of platinum nanoparticles for the design of nanoparticle-based applications. The ReaxFF force field parameters are fitted against a quantum mechanical (QM) training set containing the adsorption energy of Cl and dissociative HCl on Pt (100) and Pt (111), the energy-volume relations of PtCl2 crystals, and Cl diffusion on Pt (100) and Pt (111). ReaxFF accurately reproduces the QM training set for structures and energetics of small clusters and PtClx crystals. The predictive capacity of the force field was manifested in molecular dynamics simulations of the Cl2 and HCl molecules interactions on the (100) and)111(surfaces of c-Pt crystalline solid slabs. The etching ratio between HCl and Cl2 are compared to experimental results, and satisfactory results are obtained, indicating that this ReaxFF protocol provides a useful tool for studying the atomistic-scale details of the etching process.

Modeling and Design of All-Solid-State Batteries

Author : Hanmei Tang
Publisher :
ISBN 13 :
Total Pages : 105 pages
Book Rating : 4.:/5 (113 download)

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Book Synopsis Modeling and Design of All-Solid-State Batteries by : Hanmei Tang

Download or read book Modeling and Design of All-Solid-State Batteries written by Hanmei Tang and published by . This book was released on 2019 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: All-solid-state batteries show its great potential for being the next-generation source of clean energy barely with safety issues. While current research progress suggests the bottleneck of commercialization of all-solid-state batteries is the high resistivity at the electrode/SE interfaces. The aim of this thesis is to demonstrate how computational efforts can help understand and tackle the interface issues. The content comprises the following three projects: the methodology development (Chapter 2), the optimization of bulk materials (Chapter 3), and combined experimental and theoretical investigation into reactive interfaces (Chapter 4 & 5). In the first project, we aimed to develop and improve the computational workflow in material science research, especially those related to the interfaces. In the first part of this project, the Nudged Elastic Band (NEB) workflow has been developed with high automation and flexibility; and in the second part, an extension to a traditional molecular dynamics workflow specifically for tracking interface reactions has been implemented. The intrinsic properties of bulk materials are important to the interfacial properties and, thus, the performance of the full-cell battery. In the second project, we illustrated a computational aided design of bulk material, the Mg-doped Na3V2(PO4)3 cathode Na3+xV2-xMgx(PO4)3/C. The third project includes chapters 4 & 5, which are interfacial investigations on Na-ion and Li-ion, respectively. In chapter 4, we have demonstrated how thermodynamic approximations based on assumptions of fast alkali diffusion and multi-species equilibrium can be used to effectively screen combinations of Na-ion electrodes, solid electrolytes and buffer oxides for electrochemical and chemical compatibility. In addition to the thermodynamic approximation, ab initio molecular dynamics simulations of the NaCoO 2 /Na 3 PS 4 interface model predict that the formation of [SO4]2- -containing compounds and Na3P are kinetically favored over the formation of [PO4]3- -containing compounds, which has been validated through XPS recently. Chapter 5 investigate the source of reactivity between the sulfide solid electrolyte Li6PS5Cl (LPSCl) and the high-voltage cathode LiNi0.85Co0.1Al0.05O2 (NCA). And both experimental and computational results demonstrated improved stability between NCA and LPSCl after incorporation of the LiNbO 3 coating.

Interfaces, Phenomena, and Nanostructures in Lithium Batteries

Author : Albert R. Landgrebe
Publisher : The Electrochemical Society
ISBN 13 : 9781566773058
Total Pages : 370 pages
Book Rating : 4.7/5 (73 download)

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Book Synopsis Interfaces, Phenomena, and Nanostructures in Lithium Batteries by : Albert R. Landgrebe

Download or read book Interfaces, Phenomena, and Nanostructures in Lithium Batteries written by Albert R. Landgrebe and published by The Electrochemical Society. This book was released on 2001 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:

ReaxFF Reactive Force-field Modeling of High-capacity Electrodes in Lithium Ion Batteries and Two Dimensional Materials

Author : Alireza Ostadhossein
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (959 download)

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Book Synopsis ReaxFF Reactive Force-field Modeling of High-capacity Electrodes in Lithium Ion Batteries and Two Dimensional Materials by : Alireza Ostadhossein

Download or read book ReaxFF Reactive Force-field Modeling of High-capacity Electrodes in Lithium Ion Batteries and Two Dimensional Materials written by Alireza Ostadhossein and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. Development and application of ReaxFF for Energy Storage Materials Energy storage as a key aspect of assimilating renewable energy sources in power grids made the development of high capacity batteries an important technical challenge. The proliferation of portable electronics, hybrid electric vehicles (HEVs), and large scale energy storage has drawn significant attention toward the development of new generation-Lithium ion batteries (LIBs). Currently, most of commercial LIBs use graphitic anodes due to its long cycle life, high conductivity, abundance, and relatively low cost. However, the low specific charge capacity "(375 mAh" "g" ^"-1" ")" of graphite caused researchers to dedicate extensive attempts to find better alternative anode materials. Among all potential anodes, Silicon (Si), which can host a large amount of Lithium (Li) - each silicon atom can host up to 4.4 lithium atoms - is the most promising candidate. Nevertheless, associated with its large charge capacity of" 4200 mAh" "g" ^"-1" , insertion of lithium into silicon causes a large volumetric expansion of up to" 300%" , resulting in mechanical degradation and fracture. On the other side of the battery, the cathode, which mainly controls the voltage of LIB, should be tailored so that it can react with Li in a reversible manner. Sulfur (S) has been identified as one of most promising cathode materials for its high theoretical capacity, five times higher than that of the LiCoO2/graphite system. However, since the capacity of sulfur and its intermediate lithium polysulfide products rapidly decay due to the dissolution of intermediate polysulfides into the electrolytes, the commercialization of Li/S has been hindered. In this thesis study, systematic Molecular Dynamics (MD) simulations have been performed using ReaxFF reactive potentials to study the atomistic mechanisms governing the chemo-mechanical degradation in high-energy density anode and cathode materials. Our modeling results have shed light on the electrochemical insertion process of Li into the new high-capacity electrodes and have provided fundamental guidance to the rational designs of the next generation high capacity electrode materials with enhanced capacity retention and durability. 2. Application of ReaxFF for tow-dimensional materialsWhile the first part of this thesis covers battery applications, the second part of this thesis is devoted to the application and development of ReaxFF to model two-dimensional (2D) materials. The discovery of graphene in 2004 was the moment of the birth of an emerging research realm of 2D materials. Due to its exceptional electronic, optoelectronic and chemo-mechanical properties, graphene became ushers in the field of nano-transistors, photovoltaics, light emitting devices, optical sensors and topological field effect transistors. However, the ever increasing demands of semiconductor industry to utilize novel materials with a wider band-gap and superior structural, thermal and electrical properties has stimulated extensive scientific efforts to develop and synthesis of new generation of graphene-liked 2D-materials. Of the various proposed materials, transition metal dichalcogenides (TMDCs), such as MoS2 and WS2 have been recognized as promising candidates. It is well established that mechanical strain and geometry changes could dramatically affect the band structure and in turn electronic properties of 2D materials and in turn affect the performance and workability of the nano-transistors made of these materials. In this study, we present the development of a new ReaxFF reactive potential which can accurately describe the thermodynamic and structural properties of MoS2 sheets. Extensive Density Functional Theory (DFT) simulations are carried out to produce the required data-set for optimization of the new empirical potential parameters. This force field is able to accurately predict the mechanical properties and elastic constants of single layer MoS2. The newly developed potential is also successfully applied to estimate the formation energies of various types of point-defects (5 different vacancy types) along with the vacancy migration barriers and transition of 2H (semiconducting) 1T (metallic) phases. The energetics of ripplocations, a recently observed defect in van der Waals layers, is examined and the interplay between these defects and sulfur (S) vacancies is studied. As strain-engineering of MoS2 sheets is as an effective way to manipulate the electronic and optical properties of this material, the new ReaxFF description can provide a comprehensive insight about the morphological changes under various conditions of loading and defects to further tuning the band-gap properties in these 2D-structures. Recent experimental advances however confirm the possibility of further tuning the electronic properties of MoS2 through the fabrication of single-layer heterostructures consisting of semiconducting (2H) and metallic (1T) MoS2 phases. However, despite of technological and scientific interests, there exist limited information concerning the mechanical properties of these systems. Consequently, this investigation aims to provide a general vision regarding the mechanical properties of all-MoS2 single-layer structures at room temperature. This goal was achieved by performing extensive classical molecular dynamics simulations using a recently developed RexFF forcefield. We first studied the chirality dependent mechanical properties of defect-free 2H and 1T phases. Our atomistic modeling results for pristine 2H MoS2 were found to agree fairly well with the experimental tests. We finally discussed the mechanical response of 2H/1T single layer heterostructures. Our atomistic results suggest all-MoS2 heterostructures as suitable candidates to reach a strong and flexible material with tunable electronic properties.

ReaxFF And EReaxFF Reactive Force Field Development And Applications To Energy Storage Interfaces

Author : Md Jamil Hossain
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis ReaxFF And EReaxFF Reactive Force Field Development And Applications To Energy Storage Interfaces by : Md Jamil Hossain

Download or read book ReaxFF And EReaxFF Reactive Force Field Development And Applications To Energy Storage Interfaces written by Md Jamil Hossain and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The depletion of fossil fuels necessitates alternate and clean energy sources. Lithium-ion batteries and solid oxide electrocatalysis devices are some of the most popular candidates. However, further improvements of these energy storage devices are essential in order to meet the ever-increasing global energy demand. Improvement of the performance of these high energy chemical systems is directly linked to the understanding and improving the complex physical and chemical phenomena and exchanges that take place at their different interfaces. Surfaces or interfaces, structures created between dissimilar media, such as liquids and solids, and interphases, structures arising in between these dissimilar media, present great challenges for their study and understanding since these are the regions where myriad events such as electron transfer, ion transfer and migration, reactions, and solvation/desolvation processes take place and significantly alter their landscape. In order to investigate the physical and chemical interactions at the interfaces of energy storage devices such as Li-ion batteries and solid oxide electrocatalysis devices, we used ReaxFF and eReaxFF reactive molecular dynamics simulations in the following research areas: 1) In the electrode/electrolyte interface of a typical lithium-ion battery a solid electrolyte interphase layer is formed as a result of electrolyte decomposition during the initial charge/discharge cycles. Electron leakage from anode to the electrolyte reduces the Li+-ion and makes them more reactive resulting in decomposition of the organic electrolyte. To study the Li-electrolyte solvation, solvent exchange and subsequent solvent decomposition reactions at the anode/electrolyte interface, we have extended existing ReaxFF reactive force field parameter sets to organic electrolyte species such as ethylene carbonate, ethyl methyl carbonate, vinylene carbonate and LiPF6 salt. Density Functional Theory (DFT) data describing Li-associated initiation reactions for the organic electrolytes and binding energies of Li-electrolyte solvation structures were generated and added to existing ReaxFF training data and subsequently, we trained the ReaxFF parameters with the aim to find the optimal reproduction of the DFT data. In order to discern the characteristics of Li neutral and cation, we have introduced a second Li parameter set to describe Li+-ion. ReaxFF is trained for Li-neutral and Li+-cation to have similar solvation energies but unlike the neutral Li, Li+ will not induce reactivity in the organic electrolyte. Solvent decomposition reactions are presumed to happen once Li+-ions are reduced to Li-atoms, which can be simulated using a Monte-Carlo type atom modification within ReaxFF. This newly developed force field is capable of distinguishing between a Li-atom and a Li+-ion properly. Moreover, it is found that the solvent decomposition reaction barrier is a function of the number of EC molecules solvating the Li-atom. 2) Graphene, a 2D material arranged in an sp2-bonded hexagonal network, is one of the most promising materials for lithium-ion battery anodes due to its superior electronic conductivity, high surface area for lithium intercalation, fast ionic diffusivity and enhanced specific capacity. A detailed atomistic modeling of electronic conduction and non-zero voltage simulations of graphitic materials require the inclusion of an explicit electronic degree of freedom. To enable large length and time scale simulations of electron conduction in graphitic anodes, we developed an eReaxFF force field describing graphitic materials with an explicit electron concept. The newly developed force field, verified against quantum chemistry-based data describing, amongst others, electron affinities and equation of states, reasonably reproduces the behavior of electron conductivity in pristine and imperfect graphitic materials at different applied temperatures and voltages. Our eReaxFF description is capable of simulating leakage of excess electrons from graphene which are captured by exposed lithium ions; a common behavior at the anode/electrolyte interface of a lithium-ion battery. Finally, the initiation of Li-metal-plating observed at the graphene surface reveals the eReaxFF force field's potential for the future development of Li-graphene interactions with explicit electrons. 3) Electrocatalysis results in the change of the rate of an electrochemical reaction occurring on an electrode surface by varying the electrical potential. Electrocatalysis can be used in hydrogen generation and the generated hydrogen can be stored for future use in fuel cells for clean electricity. The use of solid oxide in electrocatalysis specially in hydrogen evolution reaction is promising. To enable large length and time scale atomistic simulations of solid oxide electrocatalysis for hydrogen generation, we developed an eReaxFF force field for barium zirconate doped with 20 mol% of yttrium (BZY20). All parameters for the eReaxFF were optimized to reproduce quantum mechanical (QM) calculations on relevant condensed phase and cluster systems describing oxygen vacancies, vacancy migrations, water adsorption, water splitting and hydrogen generation on the surfaces of the BZY20 solid oxide. Using the developed force field, we performed zero-voltage molecular dynamics simulations to observe water adsorption and the eventual hydrogen production. Based on our simulation results, we conclude that this force field sets a stage for the introduction of explicit electron concept in order to simulate electron conductivity and non-zero voltage effects on hydrogen generation. Overall, the work described in this dissertation demonstrate how atomistic-scale simulations can enhance our understanding of processes at interfaces in energy storage materials.

Materials for Lithium-Ion Batteries

Author : Christian Julien
Publisher : Springer Science & Business Media
ISBN 13 : 9780792366508
Total Pages : 658 pages
Book Rating : 4.3/5 (665 download)

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Book Synopsis Materials for Lithium-Ion Batteries by : Christian Julien

Download or read book Materials for Lithium-Ion Batteries written by Christian Julien and published by Springer Science & Business Media. This book was released on 2000-10-31 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lithium-ion battery comprises essentially three components: two intercalation compounds as positive and negative electrodes, separated by an ionic-electronic electrolyte. Each component is discussed in sufficient detail to give the practising engineer an understanding of the subject, providing guidance on the selection of suitable materials in actual applications. Each topic covered is written by an expert, reflecting many years of experience in research and applications. Each topic is provided with an extensive list of references, allowing easy access to further information. Readership: Research students and engineers seeking an expert review. Graduate courses in electrical drives can also be designed around the book by selecting sections for discussion. The coverage and treatment make the book indispensable for the lithium battery community.

Multiscale Chemo-mechanical Mechanics of High-capacity Anode Materials in Lithium-ion Nano-batteries

Author : Hui Yang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (94 download)

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Book Synopsis Multiscale Chemo-mechanical Mechanics of High-capacity Anode Materials in Lithium-ion Nano-batteries by : Hui Yang

Download or read book Multiscale Chemo-mechanical Mechanics of High-capacity Anode Materials in Lithium-ion Nano-batteries written by Hui Yang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rechargeable lithium-ion batteries (LIBs), which are the most prevailing and promising electrochemical energy storage and conversion devices due to their high energy density and design flexibility, are widely used in portable electronics and electric vehicles. Currently commercialized LIBs adopt graphite as anode for its long cycle life, abundant material supply, and relatively low cost. However, graphite suffers low specific charge capacity (372 mAhg-1), which is obviously insufficient for powering new generation electronic devices. Thus, considerable efforts are being undertaking to develop alternative anode materials with low cost, high capacity, and long cycle life. A variety of high capacity anode materials have been identified, and silicon (Si) stands as the leading candidate and has attracted much attention for its highest theoretical capacity (4200 mAhg-1). Nevertheless, inherent to the high-capacity electrodes, lithium (Li) insertion-extraction cycling induces huge volumetric expansion and stress inside the electrodes, leading to fracture, pulverization, electrical disconnectivity, and ultimately huge capacity loss. Therefore, a fundamental understanding of the degradation mechanisms in the high-capacity anodes during lithiation-delithiation cycling is crucial for the rational design of next-generation failure-resistant electrodes.In this thesis, a finite-strain chemo-mechanical model is formulated to study the lithiation-induced phase transformation, morphological evolution, stress generation and fracture in high capacity anode materials such as Si and germanium (Ge). The model couples Li reaction-diffusion with large elasto-plastic deformation in a bidirectional manner: insertion of the Li into electrode generates localized stress, which in turn mediates electrochemical insertion rates. Several key features observed from recent transmission electron microscopy (TEM) studies are incorporated into the modeling framework, including the sharp interface between the lithiated amorphous shell and unlithiated crystalline core, crystallographic orientation-dependent electrochemical reaction rate, and large-strain plasticity. The simulation results demonstrate that the model faithfully predicts the anisotropic swelling of lithiated crystalline silicon nanowires (c-SiNWs) observed from previous experimental studies. Stress analysis reveals that the SiNWs are prone to surface fracture at the angular sites where two adjacent facets intersect, consistent with previous experimental observations. In addition, Li insertion can induce high hydrostatic pressure at and closely behind the reaction front, which can lead to the lithiation retardation observed by TEM studies.For a comparative study, the highly reversible expansion and contraction of crystalline germanium nanoparticles (c-GeNPs) under lithiation-delithiation cycling are reported. During multiple cycles to the full capacity, the GeNPs remain robust without any visible cracking despite ~260% volume changes, in contrast to the size dependent fracture of crystalline silicon nanoparticles (c-SiNPs) upon the first lithiation. The comparative study of c-SiNPs, c-GeNPs, and amorphous SiNPs (a-SiNPs) through in-situ TEM and chemo-mechanical modeling suggest that the tough behavior of c-GeNPs and a-SiNPs can be attributed to the weak lithiation anisotropy at the reaction front. In the absence of lithiation anisotropy, the c-GeNPs and a-SiNPs experience uniform hoop tension in the surface layer without the localized high stress and therefore remain robust throughout multicycling. In addition, the two-step lithiation in a-SiNPs can further alleviate the abruptness of the interface and hence the incompatible stress at the interface, leading to an even tougher behavior of a-SiNPs. Therefore, eliminating the lithiation anisotropy presents a novel pathway to mitigate the mechanical degradation in high-capacity electrode materials. In addition to the study of the retardation effect caused by lithiation self-generated internal stress, the influence of the external bending on the lithiation kinetics and deformation morphologies in germanium nanowires (GeNWs) is also investigated. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, bending a GeNW during lithiation breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The chemo-mechanical modeling further corroborates the experimental observations and suggests the stress dependence of both Li diffusion and interfacial reaction rate during lithiation. The finding that external load can mediate lithiation kinetics opens new pathways to improve the performance of electrode materials by tailoring lithiation rate via strain engineering. Furthermore, in the light of bending-induced symmetry breaking of lithiation, the mechanically controlled flux of the secondary species (i.e., Li) features a novel energy harvesting mechanism through mechanical stress.Besides the continuum level chemo-mechanical modelings, molecular dynamics simulations with the ReaxFF reactive force field are also conducted to investigate the fracture mechanisms of lithiated graphene. The simulation results reveal that Li diffusion toward the crack tip is both energetically and kinetically favored owing to the crack-tip stress gradient. The stress-driven Li diffusion results in Li aggregation around the crack tip, chemically weakening the crack-tip bond and at the same time causing stress relaxation. As a dominant factor in lithiated graphene, the chemical weakening effect manifests a self-weakening mechanism that causes the fracture of the graphene. Moreover, lithiation-induced fracture mechanisms of defective single-walled carbon nanotubes (SWCNTs) are elucidated by molecular dynamics simulations. The variation of defect size and Li concentration sets two distinct fracture modes of the SWCNTs upon uniaxial stretch: abrupt and retarded fracture. Abrupt fracture either involves spontaneous Li weakening of the propagating crack tip or is absent of Li participation, while retarded fracture features a "wait-and-go" crack extension process in which the crack tip periodically arrests and waits to be weakened by diffusing Li before extension resumes. The failure analysis of the defective CNTs upon lithiation, together with the cracked graphene, provides fundamental guidance to the lifetime extension of high capacity anode materials.

Optimization of Mechanical and Electrochemical Performances of Silicon Electrode in Lithium-ion Batteries

Author : Qifang Yin
Publisher :
ISBN 13 :
Total Pages : 148 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Optimization of Mechanical and Electrochemical Performances of Silicon Electrode in Lithium-ion Batteries by : Qifang Yin

Download or read book Optimization of Mechanical and Electrochemical Performances of Silicon Electrode in Lithium-ion Batteries written by Qifang Yin and published by . This book was released on 2018 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Ab-Initio Modeling of Degradation Mechanisms in Redox-Flow and Solid-State Batteries

Author : Nadia N. Intan
Publisher :
ISBN 13 : 9781392749425
Total Pages : 0 pages
Book Rating : 4.7/5 (494 download)

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Book Synopsis Ab-Initio Modeling of Degradation Mechanisms in Redox-Flow and Solid-State Batteries by : Nadia N. Intan

Download or read book Ab-Initio Modeling of Degradation Mechanisms in Redox-Flow and Solid-State Batteries written by Nadia N. Intan and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ever increasing energy demand calls for development of energy storage and conversion technologies that can efficiently utilize available renewable energy. In recent years, there has been an immense interest in electrochemically active materials for secondary batteries, most prominently lithium-ion batteries (LIBs) that were developed primarily for portable electronics and now being also used in electric vehicles. At the large scale, redox flow batteries (RFBs) have been attracting increasing attention as stationary energy storage systems that can be connected to an electrical grid and are capable of storing up to hundreds of megawatt-hours of energy. While prior efforts have been predominantly focused on the development of new materials with superior energy characteristics, stability and degradation of electrochemical materials under operation conditions leading to the battery capacity fading have received much less attention. One of the major contributions to the capacity loss in secondary batteries is the formation of passivation layers at the materials interfaces such as electrode/ electrolyte and membrane/electrolyte. Our current atomistic understanding of how chemical reaction dynamics at these interfaces affects capacity fading and the overall battery performance is still limited. The overarching goal of this research project is to provide a better fundamental understanding of this aspect of interfacial chemistry on the example of LIBs and RFBs. Specifically, by employing a combination of density-functional-theory (DFT) based static and molecular dynamics simulations we investigate interfacial behavior focusing on the interactions of: 1) between aqueous electrolyte species and Nafion membrane in all-vanadium RFBs leading to the membrane blockage, and 2) between organic electrolyte species and cathode materials in LIBs leading to electrolyte decomposition and transition-metal dissolution at the interface. By combining the obtained theoretical insights with recent experimental observations, we aim to fill the gap in our microscopic understanding of materials interfacial chemistry leading to detrimental effects in both LIBs and RFBs.

Classical And Quantum Dynamics In Condensed Phase Simulations: Proceedings Of The International School Of Physics

Author : Bruce J Berne
Publisher : World Scientific
ISBN 13 : 9814496057
Total Pages : 881 pages
Book Rating : 4.8/5 (144 download)

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Book Synopsis Classical And Quantum Dynamics In Condensed Phase Simulations: Proceedings Of The International School Of Physics by : Bruce J Berne

Download or read book Classical And Quantum Dynamics In Condensed Phase Simulations: Proceedings Of The International School Of Physics written by Bruce J Berne and published by World Scientific. This book was released on 1998-06-17 with total page 881 pages. Available in PDF, EPUB and Kindle. Book excerpt: The school held at Villa Marigola, Lerici, Italy, in July 1997 was very much an educational experiment aimed not just at teaching a new generation of students the latest developments in computer simulation methods and theory, but also at bringing together researchers from the condensed matter computer simulation community, the biophysical chemistry community and the quantum dynamics community to confront the shared problem: the development of methods to treat the dynamics of quantum condensed phase systems.This volume collects the lectures delivered there. Due to the focus of the school, the contributions divide along natural lines into two broad groups: (1) the most sophisticated forms of the art of computer simulation, including biased phase space sampling schemes, methods which address the multiplicity of time scales in condensed phase problems, and static equilibrium methods for treating quantum systems; (2) the contributions on quantum dynamics, including methods for mixing quantum and classical dynamics in condensed phase simulations and methods capable of treating all degrees of freedom quantum-mechanically.

Lithium-ion Batteries

Author : Perla B. Balbuena
Publisher : World Scientific
ISBN 13 : 1860943624
Total Pages : 424 pages
Book Rating : 4.8/5 (69 download)

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Book Synopsis Lithium-ion Batteries by : Perla B. Balbuena

Download or read book Lithium-ion Batteries written by Perla B. Balbuena and published by World Scientific. This book was released on 2004 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This invaluable book focuses on the mechanisms of formation of a solid-electrolyte interphase (SEI) on the electrode surfaces of lithium-ion batteries. The SEI film is due to electromechanical reduction of species present in the electrolyte. It is widely recognized that the presence of the film plays an essential role in the battery performance, and its very nature can determine an extended (or shorter) life for the battery. In spite of the numerous related research efforts, details on the stability of the SEI composition and its influence on the battery capacity are still controversial. This book carefully analyzes and discusses the most recent findings and advances on this topic.

Journal, Issue 1

Author : Iron and Steel Institute
Publisher : Arkose Press
ISBN 13 : 9781343950955
Total Pages : 840 pages
Book Rating : 4.9/5 (59 download)

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Book Synopsis Journal, Issue 1 by : Iron and Steel Institute

Download or read book Journal, Issue 1 written by Iron and Steel Institute and published by Arkose Press. This book was released on 2015-10-04 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work.This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

Battery Management Systems

Author : H.J. Bergveld
Publisher : Springer Science & Business Media
ISBN 13 : 9401708436
Total Pages : 311 pages
Book Rating : 4.4/5 (17 download)

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Book Synopsis Battery Management Systems by : H.J. Bergveld

Download or read book Battery Management Systems written by H.J. Bergveld and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: Battery Management Systems - Design by Modelling describes the design of Battery Management Systems (BMS) with the aid of simulation methods. The basic tasks of BMS are to ensure optimum use of the energy stored in the battery (pack) that powers a portable device and to prevent damage inflicted on the battery (pack). This becomes increasingly important due to the larger power consumption associated with added features to portable devices on the one hand and the demand for longer run times on the other hand. In addition to explaining the general principles of BMS tasks such as charging algorithms and State-of-Charge (SoC) indication methods, the book also covers real-life examples of BMS functionality of practical portable devices such as shavers and cellular phones. Simulations offer the advantage over measurements that less time is needed to gain knowledge of a battery's behaviour in interaction with other parts in a portable device under a wide variety of conditions. This knowledge can be used to improve the design of a BMS, even before a prototype of the portable device has been built. The battery is the central part of a BMS and good simulation models that can be used to improve the BMS design were previously unavailable. Therefore, a large part of the book is devoted to the construction of simulation models for rechargeable batteries. With the aid of several illustrations it is shown that design improvements can indeed be realized with the presented battery models. Examples include an improved charging algorithm that was elaborated in simulations and verified in practice and a new SoC indication system that was developed showing promising results. The contents of Battery Management Systems - Design by Modelling is based on years of research performed at the Philips Research Laboratories. The combination of basic and detailed descriptions of battery behaviour both in chemical and electrical terms makes this book truly multidisciplinary. It can therefore be read both by people with an (electro)chemical and an electrical engineering background.

Molecular Technology, Volume 2

Author : Hisashi Yamamoto
Publisher : John Wiley & Sons
ISBN 13 : 3527341625
Total Pages : 400 pages
Book Rating : 4.5/5 (273 download)

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Book Synopsis Molecular Technology, Volume 2 by : Hisashi Yamamoto

Download or read book Molecular Technology, Volume 2 written by Hisashi Yamamoto and published by John Wiley & Sons. This book was released on 2018-12-10 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by foremost leaders in chemical research together with a number of distinguished international authors, Volume 2 presents the most important and promising recent chemical developments in life sciences, neatly summarized in one book. Interdisciplinary and application-oriented, this ready reference focuses on methods and processes with a high practical aspect, covering new trends in drug delivery, in-vivo analysis, structure formation and much more. Of great interest to chemists and life scientists in academia and industry.

Handbook of Battery Materials

Author : Claus Daniel
Publisher : John Wiley & Sons
ISBN 13 : 3527637192
Total Pages : 973 pages
Book Rating : 4.5/5 (276 download)

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Book Synopsis Handbook of Battery Materials by : Claus Daniel

Download or read book Handbook of Battery Materials written by Claus Daniel and published by John Wiley & Sons. This book was released on 2012-12-21 with total page 973 pages. Available in PDF, EPUB and Kindle. Book excerpt: A one-stop resource for both researchers and development engineers, this comprehensive handbook serves as a daily reference, replacing heaps of individual papers. This second edition features twenty percent more content with new chapters on battery characterization, process technology, failure mechanisms and method development, plus updated information on classic batteries as well as entirely new results on advanced approaches. The authors, from such leading institutions as the US National Labs and from companies such as Panasonic and Sanyo, present a balanced view on battery research and large-scale applications. They follow a distinctly materials-oriented route through the entire field of battery research, thus allowing readers to quickly find the information on the particular materials system relevant to their research.

Electrochemical Energy Storage

Author : Jean-Marie Tarascon
Publisher : John Wiley & Sons
ISBN 13 : 1118998146
Total Pages : 96 pages
Book Rating : 4.1/5 (189 download)

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Book Synopsis Electrochemical Energy Storage by : Jean-Marie Tarascon

Download or read book Electrochemical Energy Storage written by Jean-Marie Tarascon and published by John Wiley & Sons. This book was released on 2015-02-23 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electrochemical storage of energy has become essential in assisting the development of electrical transport and use of renewable energies. French researchers have played a key role in this domain but Asia is currently the market leader. Not wanting to see history repeat itself, France created the research network on electrochemical energy storage (RS2E) in 2011. This book discusses the launch of RS2E, its stakeholders, objectives, and integrated structure that assures a continuum between basic research, technological research and industries. Here, the authors will cover the technological advances as well as the challenges that must still be resolved in the field of electrochemical storage, taking into account sustainable development and the limited time available to us.