Download or read book A Multi faceted Approach Towards Improving the Performance of Silicon Electrodes for Next generation Lithium ion Batteries written by Michael Melnyk and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Although lithium-ion battery technology has been the catalyst in enabling modern electric vehicle, mobile device, and large-scale energy storage technology, the increasing power demands by end-users has motivated research in developing the next-generation of lithium-ion batteries. This next generation of batteries will need to achieve higher energy and power densities, while remaining chemically stable. Silicon-based active material has been proposed as a solution in achieving superior battery performance, as it can offer a lithium storage capacity (4200 mAh/g) tenfold higher than the carbonaceous electrodes employed in commercial Li-ion cells, while also offering superior safety characteristics. Unfortunately, the higher lithium storage capacity translates into an immense volume expansion (300 - 400%) upon lithiation, and thus the mechanical integrity and electrochemical performance of the electrodes are very unstable. Within the past decade, the performance of Si-based electrodes has been greatly improved as active material morphologies, polymer binders, electrolyte additives, and theoretical models have provided solutions in alleviating the stresses and strains generated during Si lithiation/delithiation. A multi-faceted solution pathway is enacted in this research to develop a Si-based electrode that can achieve cycling performance relevant to industrial application, while also offering insight on the influence of several aspects of the Si-based electrode design on cycling performance. From this investigation, a Si-based electrode has been developed with carbon-coated silicon monoxide active material and polyacrylic acid polymer binder, both of which offer several complimentary attributes that enable a moderately stable cycling performance at high active mass loading while offering a gravimetric and areal lithium capacity magnitude relevant to industrial applications. Although much work lies ahead in further improving the capacity retention of the Si-based electrodes reported in this thesis, this work presents an economical platform for future work on the topic.

Download or read book Silicon Based Thin Film Anodes for Next Generation Lithium Ion Battery written by Polat Karahan Billur Deniz and published by LAP Lambert Academic Publishing. This book was released on 2015-08-12 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, the selection criteria for material and production process are explained to improve the capacity and the cycle life of negative electrodes for lithium ion battery. In this sense, importance of Si thin film anode has been widely discussed. Among alternative production processes, magnetron sputtering is highlighted since it leads to form highly adherent amorphous/nano-sized crystaline structured film due to energetic particles deposition. Moreover to improve the electonic conductivity and to promote the mechanical resistance, Cu atoms are deposited with Si. The test results of different Si-Cu films show that compositionally graded film represents the most promising anode material because high Cu content at the bottom of the film enhances the adhesion and the low Cu content on top increases the capacity and the reversibility of lithiation/delithiation reactions. In the concept of the book, a clear understanding on the relationship between morphological, structural design and electrochemical performance of the thin films has been made. This would increase the likelihood of making high capacity anodes for next generation lithium ion batteries.

Download or read book Development of High Performance Next generation Li ion Battery Electrode Materials written by Brennan James Campbell and published by . This book was released on 2016 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: As of late, there has been an increasing interest in research to characterize and develop a new generation of Li-ion electrode materials that exhibit Li storage performance that goes beyond the incumbent Li-ion chemistries, such as graphite and lithium cobalt oxide, or LCO. LCO, pioneered by Dr. John B. Goodenough in the 1980s, has prevailed as the most common Li-ion cathode for decades, serving as a relatively stable, energy dense intercalation material with a high operating voltage and specific energy of 3.6V (nominal) and 240 Wh/kg, respectively. As well, graphite has served as the most ubiquitous secondary battery anode for an even longer period of time. As a light, cheap and reliable material, the stacks of carbon sheets within graphite have acted as a robust host for lithium, allowing the Li ions to be inserted and removed for hundreds and thousands of cycles at a low voltage. The principle method of preparing these electrode materials has been though large-scale slurry-casting on to metal foils, calendaring, and winding into various form factors, such as cylindrical or pouch. The slurry is the term used for the suspension of active electrode material (powderized), conductive additive (nano-sized carbon), and a dissolved binder, which acts as an adhesive and/or thickening agent. While LCO and graphite have provided the energy density and power density needed to realized various technologies up until today, there is a need to push the boundaries of rechargeable chemistries in terms of energy density, rate capability (related to power density), and more sensible battery "sandwich" configurations and architectures. Three promising electrode systems for future Li-ion batteries that will improve these characteristics are sulfur cathodes, altered carbon anodes, and silicon-based anodes.

Download or read book Approaches to Scalable High Performance Electrodes for Next Generation Lithium ion Batteries written by Jingjing Liu and published by . This book was released on 2018 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the capacity of lithium ion battery is decided by capacities of both electrodes, next-generation cathode materials also attract lots of interests. The sulfur-based cathode has attracted extensive attention because of its high capacity of 1672 mAh g-1 and its high abundance. However, the sulfur shuttling effects and the loss of active material during lithiation hinder its commercial application. To tackle these issues, we introduced polymerized organo-sulfur units to the elemental sulfur materials. The composite with 86% sulfur content was prepared using 1,3-diethynylbenzen and sulfur particles via scalable invers vulcanization. The sulfur content in copolymer sulfur was achieved as high as 86%. Our copolymer-sulfur composite cathode showed excellent cycling performance with a capacity of 454 mAh g-1 at 0.1 C after 300 cycles. We demonstrate that the organosulfur-DEB units in the sulfur cathode serve as the 'plasticizer' to effectively prevent the polysulfide shuttling.

Download or read book Silicon Anode Systems for Lithium Ion Batteries written by Prashant N. Kumta and published by Elsevier. This book was released on 2021-09-13 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intro -- Silicon Anode Systems for Lithium-Ion Batteries -- Copyright -- Contents -- Contributors -- Preface -- Part I: Introduction and background -- Part II: Mechanical properties -- Part III: Electrolytes and surface electrolyte interphase issues -- Part IV: Achieving high(er) performance: Modeling and experimental perspectives -- Part V: Future directions: Novel devices and space applications -- Part I: Introduction and background -- Chapter 1: Silicon anode systems for lithium-ion batteries -- 1.1. Introduction -- 1.2. The SiLi alloy: A material perspective -- 1.3. The SiLi alloy: An electrode perspective -- 1.3.1.1. Volume expansion and material pulverization: The importance of size and nano-structuring -- 1.3.1.2. Pulverization and delamination: The importance of polymer composites and binders -- 1.3.1.3. The silicon/electrolyte interphase -- 1.4. Conclusions: Summary and perspective -- References -- Chapter 2: Recent advances in silicon materials for Li-ion batteries: Novel processing, alternative raw materials, and pr ... -- 2.1. Introduction -- 2.2. Hybrid and alloy-based silicon-containing materials -- 2.2.1. Carbon-silicon hybrid materials -- 2.2.2. Processing hybrid anodes: Fundamental vs. practical considerations -- 2.2.3. Silicon-metal alloy anodes -- 2.2.4. Oxide-containing anodes -- 2.3. Alternative raw materials and novel processing methods -- 2.3.1. Recycling of silicon-containing industrial sources -- 2.3.2. Silicon sourced from biomass and clays -- 2.3.3. Magnesiothermic and metallic melt processing -- 2.3.4. Nano-silicon derived from diatomite and inspired by nature -- 2.3.5. Other novel processing methods -- 2.4. Conclusions -- References -- Part II: Mechanical properties -- Chapter 3: Computational study on the effects of mechanical constraint on the performance of silicon nanosheets as anode ... -- 3.1. Introduction.

Download or read book Mitigating Mechanical Failure of Crystalline Silicon Electrodes for Lithium Batteries by Morphological Design Morphological Design of Silicon Electrode with Anisotropic Interface Reaction Rate for Lithium Ion Batteries written by and published by . This book was released on 2015 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. In conclusion, the model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.

Download or read book Investigating and Optimizing Interfacial Properties of Electrode Materials for Lithium ion and Sodium ion Batteries written by Judith Elizabeth Alvarado and published by . This book was released on 2017 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current commercial lithium ion battery utilizes "host-guest" electrodes that allow for the intercalation of lithium between the crystal lattice of the anode and cathode materials. The lithium ions are transported through the electrolyte medium during the charge/discharge process, Given their success, lithium ion batteries have now penetrated the electric vehicle market and large scale grid storage, which require batteries with much higher energy densities. To meet this demand, alternative anode and cathode chemistries are required. Consequently, this will put high strain on the electrolyte which will decompose at both low and high potentials to form a passivation layer known as the solid electrolyte interphase (SEI). Herein, the fundamental reduction mechanism of fluoroethylene carbonate (FEC) is investigated as an additive for conventional electrolytes to improve the SEI formation on various silicon anodes using a series of advanced spectroscopic and microscopic techniques. For the first time, the direct visualization of the SEI generated on the silicon nanoparticle is investigated by scanning electron microscopy and its chemical composition by electron energy loss spectroscopy. The SEI is further investigated on lithium metal anode. Highly concentrated bisalt ether electrolytes form a SEI that is dominated by salt decomposition rather than solvent decomposition, which enables high lithium metal cycling efficiencies. At high potentials the electrolyte oxidizes on the cathode to form the cathode electrolyte interphase (CEI). With the discovery of 5V cathode materials, a new electrolyte is required. Therefore, sulfone based electrolytes are studied as potential high voltage electrolyte. Combined with lithium bis(fluorosulfonyl) imide, this solvent-salt synergy addresses the traditional performance issues that develop at the interface of high voltage cathodes. The factors that affect the cycling performance of cathode materials for lithium ion batteries are also seen in sodium ion batteries. Atomic layer deposition (ALD) is widely used to improve the cycling performance, coulombic efficiency of batteries, and to maintain electrode integrity for LIBs. Therefore, this approach is used to understand the effect of Al2O3 ALD coating on P2-Na2/3Ni1/3Mn2/3O2 cathodes, which lowers the cathode impedance and improves particle morphology after cycling. Improving the electrode-electrolyte interface is critical to the development of next generation high density energy storage systems.

Download or read book Electrodes for Li ion Batteries written by Laure Monconduit and published by John Wiley & Sons. This book was released on 2015-06-02 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electrochemical energy storage is a means to conserve electrical energy in chemical form. This form of storage benefits from the fact that these two energies share the same vector, the electron. This advantage allows us to limit the losses related to the conversion of energy from one form to another. The RS2E focuses its research on rechargeable electrochemical devices (or electrochemical storage) batteries and supercapacitors. The materials used in the electrodes are key components of lithium-ion batteries. Their nature depend battery performance in terms of mass and volume capacity, energy density, power, durability, safety, etc. This book deals with current and future positive and negative electrode materials covering aspects related to research new and better materials for future applications (related to renewable energy storage and transportation in particular), bringing light on the mechanisms of operation, aging and failure.

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.

Download or read book Advanced Characterization and Modeling of Next Generation Lithium Ion Electrodes and Interfaces written by Thomas Andrew Wynn and published by . This book was released on 2020 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium ion batteries have proven to be a paradigm shifting technology, enabling high energy density storage to power the handheld device and electric automotive revolutions. However relatively slow progress toward increased energy and power density has been made since the inception of the first functional lithium ion battery. Materials under consideration for next generation lithium ion batteries include anionic-redox-active cathodes, solid state electrolytes, and lithium metal anodes. Li-rich cathodes harness anionic redox, showing increased first charge capacity well beyond the redox capacity of traditional transition metal oxides, though suffer from severe capacity and voltage fade after the first cycle. This is in part attributed to oxygen evolution, driving surface reconstruction. Solid-state electrolytes (SSEs) offer the potential for safer devices, serving as physical barriers for dendrite penetration, while hoping to enable the lithium metal anode. The lithium metal naturally exhibits the highest volumetric energy density of all anode materials. Here, we employ simulation and advanced characterization methodologies to understand the fundamental properties of a variety of next generation lithium ion battery materials and devices leading to their successes or failures. Using density functional theory, the effect of cationic substitution on the propensity for oxygen evolution was explored. Improvement in Li-rich cathode performance is predicted and demonstrated through doping of 4d transition metal Mo. Next, lithium phosphorus oxynitride (LiPON), an SSE utilized in thin film batteries, was explored. LiPON has proven stable cycling against lithium metal anodes, though its stability is poorly understood. RF sputtered thin films of LiPON are examined via spectroscopic computational methods and nuclear magnetic resonance to reveal its atomic structure, ultimately responsible for its success as a thin film solid electrolyte. A new perspective on LiPON is presented, emphasizing its glassy nature and lack of long-range connectivity. Progress toward in situ methodologies for solid-state interfaces is described, and a protocol for FIB-produced nanobatteries is developed. Cryogenic methodologies are applied to a PEO/NCA composite electrode. Cryogenic focused ion beam was shown to preserve polymer structure and morphology, enabling accurate morphological quantification and preserving the crystallinity, as observed via TEM. Last, development of in situ solid-state interface characterization is discussed.

Download or read book Advanced Silicon based Electrodes for Rechargeable Lithium ion Batteries written by Kun Feng and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The pressing environmental and ecological issues with fossil fuels, together with their long-term unsustainability have driven a mighty quest for alternative energy sources. High-performance and reliable energy conversion and storage systems play a key role in the practical application of renewable energies. Among all the current energy conversion and storage technologies, lithium ion batteries (LIBs) have successfully dominated the consumer electronics market. In addition, LIBs have also been found in the application of transportation sector such as electric bicycles, various types of electric vehicles (EVs), and even in multi-megawatt-hour systems for the utility industry. However, the state-of-art commercial LIBs are still infeasible for widespread deployment in EVs due to their energy density limit and high cost for large battery packs. To increase the energy density of LIBs, which represents the ultimate objective of this thesis, traditional electrode materials need to be replaced by new materials with higher capacity and as-reliable performance. Silicon (Si) has been intensively studied as the anode material for LIBs because of its exceptionally high specific capacity. Compared to the widely commercialized graphite anode which displays a capacity of 372 mAh g-1, Si possesses a theoretical capacity of 4200 mAh g-1 upon full lithiation with the formation of lithium Si alloy Li22Si5. However, Si-based anode materials usually suffer from large volume change during the charge and discharge process, leading to the subsequent pulverization of Si, loss of electric contact, and continuous side reactions. These transformations cause poor cycle life and hinder the wide commercialization of Si for LIBs. The lithiation/delithiation behaviors of Si, as well as the interphase reaction mechanisms, have been progressively studied and understood. Various nanostructured Si anodes have been reported to exhibit both superior specific capacity and cycle life compared to commercial carbon-based anodes. However, some practical issues with Si anodes remain and must be addressed if to be widely used in commercial LIBs. To tackle the practical challenges facing Si anodes and achieve our objective of boosting the energy density of LIBs, several feasible approaches have been proposed, and specifically embodied in the projects displayed in this thesis. Main considerations behind these approaches include: preventing Si structure failure, enhancing electronic conductivity, forming stable electrode/electrolyte interphase. This thesis will begin with an overview on current energy challenges and motivations, followed by thesis objective and approaches. A comprehensive literature review is presented on LIB technology fundamentals, key components, and more importantly, peer works on the lithiation/delithiation behaviors of Si, research focuses on Si anode development, including engineering of Si architectures, and construction of Si-based composites. Chapter 3 introduces several important characterization techniques that are used throughout the completion of thesis projects, including both physical and electrochemical characterizations, and device assembly methods. In the first study, a highly efficient Si reduced graphene oxide carbon (Si-rGO-C) composite with good rGO wrapping of Si and an interconnected carbon network is developed for the first time. Adoption of Si NPs eliminates the possibility of Si structure failure. Compared with the regular Si-rGO composites with only Si NPs wrapped by rGO that have been previously reported, Si-rGO-C composite not only improves the electrical conductivity, but also enhances structure stability. In addition to the rGO wrapping on Si NPs, the additional carbon coating on the partially exposed Si NPs provides extra protection from Si volume change that may cause detachment from rGO sheets. Carbon rods between Si-rGO flakes function as conductive bridges, creating an effective conductive network on a larger scale. The initial capacity of Si-rGO-C composite reaches 1139 mAh g-1 at 0.1 A g-1, many times that of graphite. In addition, capacity retention of 94% is obtained after 300 cycles at 1 C. In the second study, a secondary micron-sized Si-based composite (MSC) is developed, with Si NPs embedded in a porous, conductive and elastic network constructed with carbon, and cured-and-crosslinked functional binder materials. The idea of combining nano-sized Si and conductive agents is extended to the construction of a well-defined spherical structure via a facile spray-drying process. With the careful heat treatment of the composite, the polymers crosslink via the dehydration reaction of functional groups and forms a robust structure. The polymeric chains are retained in the structure since a relatively mild temperature (250 °C) is selected. In addition to the structure benefits of this composite and therefore the electrochemical performance improvement over Si NPs, tap density of Si NPs is significantly improved via the formation of secondary micron-sized particles, eventually promoting the volumetric energy density of a LIB. More importantly, this facile methodology does not require a high temperature carbonization and is implemented with a highly scalable spray-drying process. In the last study, a secondary cluster with Si NPs embedded in an amorphous carbon and TiOX matrix (C-TiOX/Si) is developed. This project is in furtherance of the ideas adopted in the previous two projects, as it integrates Si NPs onto a secondary conductive network, while a better surface coating on Si is adopted for enhanced surface protection. In this project, the C-TiOX matrix is conformally formed on the surface of Si, which not only uniformly casts a protective layer on Si, but also combines nano-sized Si into micron clusters. Thickness of the coating layer can be easily tuned, and thus a good coating quality and cluster size can be readily achieved. The amorphous and defect-rich nature of the TiOX not only exhibits enhanced electronic conductivity over its crystalline counterparts, but also provides better elasticity and stress-release capability that can maintain the structural integrity over lithiation/delithiation of Si. The conformally-formed C-TiOX matrix protects Si from direct and repetitive contact with electrolyte and help form a stable solid electrolyte interphase on the outer surface of the cluster. The final chapter concludes the work in this thesis and provides recommendations for future research directions based on the scientific findings and experience gained through the completion of this thesis.

Download or read book Mechanics of Silicon Electrodes in Lithium Ion Batteries written by Yonghao An and published by . This book was released on 2014 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: As one of the most promising materials for high capacity electrode in next generation of lithium ion batteries, silicon has attracted a great deal of attention in recent years. Advanced characterization techniques and atomic simulations helped to depict that the lithiation/delithiation of silicon electrode involves processes including large volume change (anisotropic for the initial lithiation of crystal silicon), plastic flow or softening of material dependent on composition, electrochemically driven phase transformation between solid states, anisotropic or isotropic migration of atomic sharp interface, and mass diffusion of lithium atoms. Motivated by the promising prospect of the application and underlying interesting physics, mechanics coupled with multi-physics of silicon electrodes in lithium ion batteries is studied in this dissertation. For silicon electrodes with large size, diffusion controlled kinetics is assumed, and the coupled large deformation and mass transportation is studied. For crystal silicon with small size, interface controlled kinetics is assumed, and anisotropic interface reaction is studied, with a geometry design principle proposed. As a preliminary experimental validation, enhanced lithiation and fracture behavior of silicon pillars via atomic layer coatings and geometry design is studied, with results supporting the geometry design principle we proposed based on our simulations. Through the work documented here, a consistent description and understanding of the behavior of silicon electrode is given at continuum level and some insights for the future development of the silicon electrode are provided.

Download or read book Design Fabrication and Electrochemical Performance of Nanostructured Carbon Based Materials for High Energy Lithium Sulfur Batteries written by Guangmin Zhou and published by Springer. This book was released on 2017-02-09 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the design, fabrication and applications of carbon-based materials for lithium-sulfur (Li-S) batteries. It provides insights into the localized electrochemical transition of the “solid-solid” reaction instead of the “sulfur-polysulfides-lithium sulfides” reaction through the desolvation effect in subnanometer pores; demonstrates that the dissolution/diffusion of polysulfide anions in electrolyte can be greatly reduced by the strong binding of sulfur to the oxygen-containing groups on reduced graphene oxide; manifests that graphene foam can be used as a 3D current collector for high sulfur loading and high sulfur content cathodes; and presents the design of a unique sandwich structure with pure sulfur between two graphene membranes as a very simple but effective approach to the fabrication of Li-S batteries with ultrafast charge/discharge rates and long service lives. The book offers an invaluable resource for researchers, scientists, and engineers in the field of energy storage, providing essential insights, useful methods, and practical ideas that can be considered for the industrial production and future application of Li-S batteries.

Download or read book Structural Engineering of Lithium ion Battery Electrodes for the Production of Stable Energy dense Storage written by Jason Alexander Weeks and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium-ion batteries (LIBs) have revolutionized many facets of our everyday life, enabling devices such as cell phones, laptops, and, most recently, electric vehicles to become everyday commodities for consumers. However, as the demands of consumers and the energy requirements of these devices continue to grow, so must the storage capabilities of LIBs. Unfortunately, the chemistry and design space of these devices has remained stagnant over the technology’s lifespan. Several energy-dense density chemistries, such as lithium metal, silicon, and tin, are highly regarded for their lithium storage capabilities,. Yet, the non-advantageous side effects of their lithiation/delithiation (dendrite formation, particle fracturing, excessive SEI growth, etc.) have prevented the practical implementation of these materials. As such, an investigation was conducted to determine how structural engineering can be used to help enable next-generation chemistries and electrode designs for higher energy-density LIBs. Lithium metal touts any anode's highest theoretical capacity and power density; however, the safety risks from dendrite formation, such as electrical short-circuiting and explosions, prevent its utilization. Employing a systematic approach to the characterization of the solid electrode interphase (SEI) displays how electrolyte composition influences the chemical makeup of the SEI and its resulting properties. These results demonstrate how the subsequent modulation of the SEI structure and composition can influence the electrochemical performance and lithium deposition morphology. Similarly, the purposeful design of alloying anode materials, like tin and lead, and their host structures can tune their performance and electrochemistry. Typically, the large mechanical stress from the volumetric expansion during lithiation causes severe capacity fade in these materials; however, implementing a carbonaceous scaffold can drastically increase the stability of these materials. In addition to examining new active materials, the structural engineering of the overall electrode is explored. Metal foil current collectors comprise approximately 15% of the total cell weight in traditional batteries. Implementing a templated slurry casting process using camphene enables the formation of free-standing electrodes with enhanced flexibility and rate capabilities. Compared to classical electrode designs, an increase of 25% in energy density can be achieved by eliminating the gravimetrically dense current collector and increasing lithiation site accessibility

Download or read book Silicon Inverse Opal based Materials as Electrodes for Lithium ion Batteries written by Alexei Esmanski and published by . This book was released on 2008 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional macroporous structures ('opals' and 'inverse opals') can be produced by colloidal crystal templating, one of the most intensively studied areas in materials science today. There are several potential advantages of lithium-ion battery electrodes based on inverse opal structures. High electrode surface, easier electrolyte access to the bulk of electrode and reduced lithium diffusion lengths allow higher discharge rates. Highly open structures provide for better mechanical stability to volume swings during cycling.Silicon is one of the most promising anode materials for lithium-ion batteries. Its theoretical capacity exceeds capacities of all other materials besides metallic lithium. Silicon is abundant, cheap, and its use would allow for incorporation of microbattery production into the semiconductor manufacturing. Performance of silicon is restricted mainly by large volume changes during cycling.The objective of this work was to investigate how the inverse opal structures influence the performance of silicon electrodes. Several types of silicon-based inverse opal films were synthesised, and their electrochemical performance was studied.Amorphous silicon inverse opals were fabricated via chemical vapour deposition and characterised by various techniques. Galvanostatic cycling of these materials confirmed the feasibility of the approach taken, since the electrodes demonstrated high capacities and decent capacity retentions. The rate performance of amorphous silicon inverse opals was unsatisfactory due to low conductivity of silicon. The conductivity of silicon inverse opals was improved by crystallisation. Nanocrystalline silicon inverse opals demonstrated much better rate capabilities, but the capacities faded to zero after several cycles.Silicon-carbon composite inverse opal materials were synthesised by depositing a thin layer of carbon via pyrolysis of a sucrose-based precursor onto the silicon inverse opals in an attempt to further increase conductivity and achieve mechanical stabilisation of the structures. The amount of carbon deposited proved to be insufficient to stabilise the structures, and silicon-carbon composites demonstrated unsatisfactory electrochemical behaviour.Carbon inverse opals were coated with amorphous silicon producing another type of macroporous composites. These electrodes demonstrated significant improvement both in capacity retentions and in rate capabilities. The inner carbon matrix not only increased the material conductivity, but also resulted in lower silicon pulverisation during cycling.

Download or read book Fast Ionic Conductors and Solid Solid Interfaces Designed for Next Generation Solid State Batteries written by and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The EV Everywhere Grand Challenge requires a breakthrough in energy storage technology. State-of-the-art Li-ion technology is currently used in low volume production plug-in hybrid and niche high performance vehicles; however, the widespread adoption of electrified powertrains requires a four-fold increase in performance, 25% lower cost, and safer batteries without the possibility of combustion. One approach for this target is to develop solid-state batteries (SSBs) offering improved performance, reduced peripheral mass, and unprecedented safety. SSB could offer higher energy density, by enabling new cell designs, such as bipolar stacking, leading to reduced peripheral mass and volume. To enable SSBs, a crucial requirement is a fast-ion conducting solid electrolyte. To date, myriad solid-state electrolytes have been reported exhibiting Li ion conductivities approaching those of today's liquid electrolyte membranes. Moreover, several new materials are reported to have wide electrochemical window and single-ion mobility. Leveraging decades of research focused on Li-based electrodes for Li-ion batteries, the discovery of new solid-state electrolytes could enable access to these electrodes; specifically, Li metal and high voltage electrodes (>5V). However, transitioning SSBs from the laboratory to EVs requires answers to fundamental questions such as: (1) how does Li-ion transport through the solid electrolyte / solid electrode interface work? (2) will solid electrolytes enable bulk-scale Li metal anode and high voltage cathodes?, and (3) how will ceramic-based cells be manufactured in large-format battery packs? The purpose of this Research Topic is to provide new insights obtained through the fundamental understanding of materials chemistry, electrochemistry, advanced analysis and computational simulations. We hope these aspects will summarize current challenges and provide opportunities for future research to develop the next generation SSBs.

Download or read book The Performance of Structured High capacity Si Anodes for Lithium ion Batteries written by Juichin Fan and published by . This book was released on 2015 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Si-VACNT composite electrodes were prepared by first synthesizing VACNTs on Si wafers using photolithography for catalyst patterning, followed by aligned CNT growth. Nano-layers of silicon were then deposited on the aligned carbon nanotubes via LPCVD at 200mTorr and 535°C. A thin copper film was used as the current collector. Electrochemical testing was performed on the electrodes assembled in a CR2025 coin cell with a metallic Li foil as the counter electrode. The impact of the electrode structure on the capacity at various current densities was investigated. Experimental results demonstrated the importance of control over the superficial area between the electrolyte and the electrode on the performance of silicon-based electrodes for next generation lithium ion batteries. In addition, the results show that Si-VACNT height does not limit Li transport for the range of the conditions tested.