Download or read book Physical and Electrochemical Investigation of Various Dinitrile Plasticizers in Highly Conductive Polymer Electrolyte Membranes for Lithium Ion Battery Application written by Chenrun Feng and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To investigate physical and electrochemical properties of polymer electrolyte membranes (PEMs) containing various dinitriles such as succinonitrile (SCN), glutaronitrile (GLN) and adiponitrile (ADN), binary and ternary phase diagrams of poly(ethylene glycol) diacrylate (PEGDA), GLN and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) blends were firstly established in this thesis. The binary phase diagram of PEGDA/GLN system was self-consistently solved based on the combined free energies of Flory-Huggins theory for liquid-liquid demixing and phase field theory for crystal solidification. Computed liquidus and solidus lines were compared with crystal melting temperatures of the binary pairs, obtained by differential scanning calorimetry (DSC) measurement. The binary phase diagram of LiTFSI/GLN system was drawn according to crystal melting temperatures of the binary pairs determined by DSC measurement. Then coexistence regions of each binary phase diagram were verified by polarized optical microscopy. Subsequently, the ternary phase diagram of PEGDA/GLN/LiTFSI at 25 °C were established. Guided by isotropic regions within ternary phase diagrams established in this thesis and previous studies, polymer electrolyte membranes (PEMs) plasticized by various dinitriles thus fabricated via photo-polymerization afforded transparent, homogeneous films. The ionic conductivity of these PEMs was determined by AC impendence spectrometer, which showed high ionic conductivity up to 10−3 S/cm at room temperature. Of particular interest is that GLN-PEM reveals the highest ion conductivity among the three PEMs tested. To analyze the electrochemical performance of PEMs used in lithium-ion batteries, SCN-PEM, GLN-PEM, and ADN-PEM were assembled into Li4Ti5O12/PEM/Li and LiFePO4/PEM/Li half-cells. The half-cell containing GLN-PEM exhibits the best charge-discharge cycling performance, which is consistent with the highest ionic conductivity of the GLN plasticized PEM.

Download or read book Polymer Electrolytes written by Tan Winie and published by John Wiley & Sons. This book was released on 2020-02-18 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the main characterization techniques of polymer electrolytes and their applications in electrochemical devices Polymer Electrolytes is a comprehensive and up-to-date guide to the characterization and applications of polymer electrolytes. The authors ? noted experts on the topic ? discuss the various characterization methods, including impedance spectroscopy and thermal characterization. The authors also provide information on the myriad applications of polymer electrolytes in electrochemical devices, lithium ion batteries, supercapacitors, solar cells and electrochromic windows. Over the past three decades, researchers have been developing new polymer electrolytes and assessed their application potential in electrochemical and electrical power generation, storage, and conversion systems. As a result, many new polymer electrolytes have been found, characterized, and applied in electrochemical and electrical devices. This important book: -Reviews polymer electrolytes, a key component in electrochemical power sources, and thus benefits scientists in both academia and industry -Provides an interdisciplinary resource spanning electrochemistry, physical chemistry, and energy applications -Contains detailed and comprehensive information on characterization and applications of polymer electrolytes Written for materials scientists, physical chemists, solid state chemists, electrochemists, and chemists in industry professions, Polymer Electrolytes is an essential resource that explores the key characterization techniques of polymer electrolytes and reveals how they are applied in electrochemical devices.

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.

Download or read book Development of Ion Conductive Polymer Gel Electrolytes and Their Electrochemical and Electromechanical Behavior Studies written by Jiao Guo and published by . This book was released on 2010 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this research is to develop novel polymer gel electrolytes that overcome the drawbacks of conventional polymer electrolytes involving aqueous solvents or small organic molecules. In order to reach this aim, a series of novel polymer gel electrolytes were developed using crosslinked polymer matrix as a physical container acting to form cage around electrolytes. This structure leads to high ion conductivity under the applied electric field while maintaining mechanical integrity. The following gel electrolytes were prepared by varying the polymer hosts and type of electrolytes. The ion gels based on free radical polymerization of methylacrylate (MMA) in ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) were transparent, self-standing and flexible with high ambient ionic conductivity in the range of 10−4~ 10−3 S/cm. The coupling effects between PMMA matrix and IL decrease with increasing the concentration of IL. The temperature dependence of ion conductivity followed Arrhenius Law, indicating a thermally activated ionic motion. Therefore, the high conductivity is considered to be due to the movement from both cations and anions to electrodes and weak polymer-ion interaction. Based on its high ion conductivity, the three layer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT/PSS) coated electroactive actuators were also developed, which exhibited a bending behavior under electrical field. The lithium polymer gels based on PMMA and modified siloxane (PEMPS) with LiTFSI exhibited transparency, flexibility and mechanical integrity, and remained miscible under all use conditions. This gel showed an ion conductivity 10−4 S/cm at 70 °C. The conductivity showed a maximum when the salt concentration increased for the composition of MMA/PEMPS = 30/70 and 40/60. At low concentration regime of solvent/salt (PEMPS/LiTFSI), the conductivity showed an increase with salt (LiTFSI) concentration. Beyond a critical salt concentration, the viscosity of the medium became high and this led to decrease of diffusion of ions in the medium and the decrease of conductivity. The conductivity was also increased with the decrease of PMMA/electrolyte ratio. The swelling ratio of PMMA network was also found to exhibit a maximum as the salt concentration increased. The swelling ratio increased as the PMMA/electrolyte ratio was decreased. The FTIR study indicates lithium salt was mostly dissociated by PEMPS, and had little interaction with PMMA polymer hosts. At last, polyvinyl alcohol (PVA)/KOH and polyacrylic acid (PAA)/KOH based aqueous gels were studied for the application in Ni-Zn batteries. The crystallization and chain entanglements formed physical crosslink for the PVA/KOH gel, while the copolymerization between acrylic acid and crosslinking agent formed the chemical crosslink for the PAA/KOH based gel. Both gels showed high ambient ion conductivity around 10−2 S/cm, satisfying the mechanical and ion conductivity requirements of the membrane for successful construction of Ni-Zn batteries.

Download or read book Ceramic and Specialty Electrolytes for Energy Storage Devices written by Prasanth Raghavan and published by CRC Press. This book was released on 2021-04-04 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ceramic and Specialty Electrolytes for Energy Storage Devices, Volume II, investigates recent progress and challenges in a wide range of ceramic solid and quasi-solid electrolytes and specialty electrolytes for energy storage devices. The influence of these electrolyte properties on the performance of different energy storage devices is discussed in detail. Features: • Offers a detailed outlook on the performance requirements and ion transportation mechanism in solid polymer electrolytes • Covers solid-state electrolytes based on oxides (perovskite, anti-perovskite) and sulfide-type ion conductor electrolytes for lithium-ion batteries followed by solid-state electrolytes based on NASICON and garnet-type ionic conductors • Discusses electrolytes employed for high-temperature lithium-ion batteries, low-temperature lithium-ion batteries, and magnesium-ion batteries • Describes sodium-ion batteries, transparent electrolytes for energy storage devices, non-platinum-based cathode electrocatalyst for direct methanol fuel cells, non-platinum-based anode electrocatalyst for direct methanol fuel cells, and ionic liquid-based electrolytes for supercapacitor applications • Suitable for readers with experience in batteries as well as newcomers to the field This book will be invaluable to researchers and engineers working on the development of next-generation energy storage devices, including materials and chemical engineers, as well as those involved in related disciplines.

Download or read book Holographically Polymerized Poly Ethylene Oxide Network As Solid Polymer Electrolytes written by Kevin T. Bazzel and published by . This book was released on 2016 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current generation has become increasingly concerned with the dangers posed by fossil fuels and have therefore turned their attention to clean energy technologies, such as electrochemical batteries and solar cells as suitable alternatives. Lithium-based batteries have emerged as the most promising energy storage for use in personal devices, transportation and general energy storage. Current lithium batteries are referred to as 'rocking chair' batteries due to the presence of lithium in its ionic rather than metallic state. These batteries are safe for commercial use, however, they severely cut into lithium's high specific capacitance properties. Consumer demands for higher battery energy densities and faster charging rates are driving research for lithium-metal batteries. Potential safety concerns arise with current liquid electrolytes in lithium-metal batteries due problematic lithium dendrite growth in the cell. Liquid electrolytes do little to prevent dendrite growth, which will eventually cause short-circuiting and possible volatile reactions. Solid polymer electrolytes have been proven to prevent dendrite growth by providing a physical barrier between the electrodes. Advancements in polymer electrolyte membranes (PEMs) are necessary to increase the potential for fuel cells, batteries, and solar conversion devices. Increasing the mechanical properties to create a mechanically robust film has a direct tradeoff of reducing ion transport and conductivity. This research is focused on decoupling ionic conductivity and mechanical properties to form a phase separated membrane capable of inhibiting dendrite growth. Holographic polymerization was used as a topdown technique to create a nanostructure with highly conductive rich phases, as well as mechanically robust phases. A new formulation has been proposed that utilizes a photo-inert low molecular poly(ethylene oxide) (PEO) which has the main mechanism for ionic conductivity. A crosslinked network composed of polyhedral oligomeric silsesquioxanes (POSS) and photoreactive PEO monomers provide the mechanical support. The mechanical and conductive properties of the phase-separated films were investigated and compared with isotropic floodlit samples. The films were shown to show exceptional low temperature conductivity and the mechanical and conductive properties were successfully decoupled through the use of holographic polymerization.

Download or read book Fast Ion Transport in Solids written by B. Scrosati and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main motivation for the organization of the Advanced Research Workshop in Belgirate was the promotion of discussions on the most recent issues and the future perspectives in the field of Solid State lonics. The location was chosen on purpose since Belgirate was the place were twenty years ago, also then under the sponsorship of NATO, the very first international meeting on this important and interdisciplinary field took place. That meeting was named "Fast Ion Transport in Solids" and gathered virtually everybody at that time having been active in any aspect of motion of ions in solids. The original Belgirate Meeting made for the first time visible the technological potential related to the phenomenon of the fast ionic transport in solids and, accordingly, the field was given the name "Solid State lonics". This field is now expanded to cover a wide range of technologies which includes chemical sensors for environmental and process control, electrochromic windows, mirrors and displays, fuel cells, high performance rechargeable batteries for stationary applications and electrotraction, chemotronics, semiconductor ionics, water electrolysis cells for hydrogen economy and other applications. The main idea for holding an anniversary meeting was that of discussing the most recent issues and the future perspectives of Solid State lonics just twenty years after it has started at the same location on the lake Maggiore in North Italy.

Download or read book Ionic Conductive Polymers for Electrochemical Devices written by Riccardo Narducci and published by . This book was released on 2022 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing levels of pollution and climate change are pushing the scientific community towards more sustainable solutions for the conversion and storage of energy. This book is dedicated to ionic conductive polymers, fundamental components of devices such as fuel cells (FCs), redox flow batteries (RFBs), and electrolyzers that can help to significantly decrease the amount of greenhouse gases emission. The book focuses on commercial polymers such as Nafion, a benchmark for proton-conducting membranes, acid doped polybenzimidazole (PBI), or blended membranes containing hyperbranched poly(arylene ether sulfone (PAES)/Linear poly(phenylene oxide) (PPO) as anion exchange membranes (AEMs). Promising and low-cost sulfonated aromatic polymers (SAP), or solid polymer blend electrolytes (SPBEs) based on natural chitosan (CS) and methylcellulose (MC). This book is also reports some strategies to enhance mechanical stability, such as cross-linking (XL), or several techniques, including classical casting methods or electrospinning (ES). I am confident that this book will serve to further stimulate advances in this research area, in both the sectors of membranes and catalysts, the first is essential for the long-term functioning of the system, and the second for a drastic reduction in costs, especially in fuel cells.

Download or read book Polymer Electrolytes written by César Sequeira and published by Woodhead Publishing. This book was released on 2016-08-19 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer electrolytes are electrolytic materials that are widely used in batteries, fuel cells and other applications such as supercapacitors, photoelectrochemical and electrochromic devices. Polymer electrolytes: Fundamentals and applications provides an important review of this class of ionic conductors, their properties and applications. Part one reviews the various types of polymer electrolyte compounds, with chapters on ceramic polymer electrolytes, natural polymer-based polymer electrolytes, composite polymer electrolytes, lithium-doped hybrid polymer electrolytes, hybrid inorganic-organic polymer electrolytes. There are also chapters on ways of characterising and modelling polymer electrolytes. Part two discusses applications such as solar cells, supercapacitors, electrochromic and electrochemical devices, fuel cells and batteries. With its distinguished editors and international team of contributors, Polymer electrolytes: Fundamentals and applications is a standard reference for all those researching and using polymer electrolytes in such areas as battery and fuel cell technology for automotive and other applications.

Download or read book Polymer Membranes for Fuel Cells written by Javaid Zaidi and published by Springer Science & Business Media. This book was released on 2010-07-15 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the late-1960’s, perfluorosulfonic acid (PFSAs) ionomers have dominated the PEM fuel cell industry as the membrane material of choice. The “gold standard’ amongst the many variations that exist today has been, and to a great extent still is, DuPont’s Nafion® family of materials. However, there is significant concern in the industry that these materials will not meet the cost, performance, and durability requirementsnecessary to drive commercialization in key market segments – es- cially automotive. Indeed, Honda has already put fuel cell vehicles in the hands of real end users that have home-grown fuel cell stack technology incorporating hydrocarbon-based ionomers. “Polymer Membranes in Fuel Cells” takes an in-depth look at the new chem- tries and membrane technologies that have been developed over the years to address the concerns associated with the materials currently in use. Unlike the PFSAs, which were originally developed for the chlor-alkali industry, the more recent hydrocarbon and composite materials have been developed to meet the specific requirements of PEM Fuel Cells. Having said this, most of the work has been based on derivatives of known polymers, such as poly(ether-ether ketones), to ensure that the critical requirement of low cost is met. More aggressive operational requi- ments have also spurred the development on new materials; for example, the need for operation at higher temperature under low relative humidity has spawned the creation of a plethora of new polymers with potential application in PEM Fuel Cells.

Download or read book Investigation of Hydroxide Ion Conducting Polymer Electrolytes for Solid Supercapacitor Applications written by Jak Li and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing clean energy demands have been incentivizing the development of next-generation energy storage technologies such as solid supercapacitors that are safe, compact, low cost, and capable of high-throughput reel-to-reel processing. While many advanced solid supercapacitors are demonstrated using hydroxide (OH-) ion conducting polymer electrolytes, the fundamental understanding of the performance of the electrolyte and its role in solid-state devices requires substantial elucidation. In this thesis, alkaline polymer electrolytes (APEs) for solid supercapacitors were developed based on tetraethylammonium hydroxide (TEAOH) and polyacrylamide (PAM) that exhibit (i) high ionic conductivity, (ii) long-term environmental stability, and (iii) good accessibility with electrode materials. An in-depth understanding of OH- ion conduction in polymer matrix and the interactions between the ionic conductor, polymer matrix, and various organic and inorganic additives has been established. The synergistic pairing of PAM and TEAOH enhanced the OH- ion conduction and prolonged its storage-life. Investigations of the dielectric properties of the TEAOH-PAM APE revealed the influence of H2O:TEAOH crystal hydrates on the ionic conductivity of the polymer electrolyte. Evaluations at elevated temperatures showed that the OH- ion conduction in the polymer electrolyte involves an interplay of segmental motion and OH- ion hopping. Correlative spectroscopic and electrochemical studies are used to determine the effects of crosslinking and the addition of inorganic filler additives on TEAOH-PAM. It was discovered that the presence and size of SiO¬2 alters the crystallization dynamics. Solid supercapacitors using TEAOH-PAM were fabricated in 3D sandwiched and 2D interdigitated configurations. The APE shows excellent compatibility with multiwalled carbon nanotubes as well as ultra-high surface area activated carbon electrodes, resulting in capacitances of ca. 10 F g-1 and ca. 240 F g-1, respectively. TEAOH-PAM was also matched with vertically-oriented graphene nanosheet (VOGN) electrodes as a 2D interdigitated device to replace traditional electrolytic capacitors for high frequency filtering applications. The combination of the highly electronically conductive VOGN electrodes and the highly ionically conductive, thermally tolerant TEAOH-PAM APE enabled a solid supercapacitor with ultra-high rate capacitive performance up to 120 Hz and outstanding thermal resiliency up to 120 °C.

Download or read book Biopolymer Electrolytes written by Sudhakar Y N and published by Elsevier. This book was released on 2018-06-09 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biopolymer Electrolytes: Fundamentals and Applications in Energy Storage provides the core fundamentals and applications for polyelectrolytes and their properties with a focus on biopolymer electrolytes. Increasing global energy and environmental challenges demand clean and sustainable energy sources to support the modern society. One of the feasible technologies is to use green energy and green materials in devices. Biopolymer electrolytes are one such green material and, hence, have enormous application potential in devices such as electrochemical cells and fuel cells. Features a stable of case studies throughout the book that underscore key concepts and applications Provides the core fundamentals and applications for polyelectrolytes and their properties Weaves the subject of biopolymer electrolytes across a broad range of disciplines, including chemistry, chemical engineering, materials science, environmental science, and pharmaceutical science

Download or read book Nanoparticle Containing Hybrid Polymer Electrolyte Membranes Using Holographic Polymerization written by Brittany L. Gallagher and published by . This book was released on 2015 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for efficient energy storage will continue to grow as limited energy resources are depleted and the use of mobile technologies increases. Lithium-ion batteries have emerged as an important energy storage alternative, but the use of volatile and flammable liquid electrolytes in commercial applications hinders the safety of these batteries. Liquid electrolytes do not prevent the growth of lithium dendrites, which are the main cause of battery failure in current devices. Solid polymer electrolytes with high mechanical properties have been researched to prevent lithium dendrite growth, but increasing mechanical integrity has a direct tradeoff of reducing ion transport and conductivity. The outstanding challenge in the field of polymer electrolytes is to simultaneously maximize both ionic conductivity and mechanical strength without sacrificing either property. This research is focused on developing an improved solid polymer electrolyte for lithium batteries which offers a combination of high conductivity and mechanical properties. Holographic polymerization was used to pattern silica nanoparticles into polymer electrolyte membranes with segregated acrylate and electrolyte domains. Nanoparticles were incorporated to improve the mechanical strength of the acrylate domain and to enhance the conductivity of the electrolyte. Holographic polymerization was utilized for long-range, defect-free, nanosize morphological control. Two optical setups were used to fabricate gratings with the layers aligned both perpendicular and parallel to the film. The distribution of the nanoparticles in the layers was investigated, in addition to their impact on conductivity, mechanical properties, and morphology. It was found that the composite electrolytes exhibited an increase in both ionic conductivity and Young0́9s modulus. The use of holographic polymerization offers an exciting alternative to produce composite polymer electrolytes with independently tunable properties for use in lithium-ion batteries.

Download or read book Applications of Ionic Liquids in Polymer Science and Technology written by David Mecerreyes and published by Springer. This book was released on 2015-04-08 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the latest knowledge in the science and technology of ionic liquids and polymers in different areas. Ionic liquids (IL) are actively being investigated in polymer science and technology for a number of different applications. In the first part of the book the authors present the particular properties of ionic liquids as speciality solvents. The state-of-the art in the use of ionic liquids in polymer synthesis and modification reactions including polymer recycling is outlined. The second part focuses on the use of ionic liquids as speciality additives such as plasticizers or antistatic agents. The third part examines the use of ionic liquids in the design of functional polymers (usually called polymeric ionic liquids (PIL) or poly(ionic liquids)). Many important applications in diverse scientific and industrial areas rely on these polymers, like polymer electrolytes in electrochemical devices, building blocks in materials science, nanocomposites, gas membranes, innovative anion sensitive materials, smart surfaces, and a countless set range of emerging applications in different fields such as energy, optoelectronics, analytical chemistry, biotechnology, nanomedicine or catalysis.

Download or read book Towards Development Of Polymeric Compounds For Energy Storage Devices And For Low Energy Loss Tires written by Prasad S. Raut and published by . This book was released on 2017 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focused on the development of polymeric materials with enhanced electrochemical performance in Li-ion batteries (LIB) and reduction of rolling resistance in tire tread compounds. The first part of the thesis is devoted to separators and electrolytes used in Li-ion batteries. Specifically, the research focused on ionogel polymer electrolytes (IGPE) for high temperature LIB operation and composite solid polymer electrolytes (CSPE) for improvement of the mechanical properties of the existing solid polymer electrolyte technology. IGPEs were fabricated by incorporating the pores of thin film syndiotactic polystyrene (sPS) gels with ionic liquid (IL). The thermal and electrochemical performance of the ionogel membrane were compared with polyolefin based electrolyte-separator technology using Li+/ graphite half-cells at room temperature and at elevated temperatures (80-100 °C). sPS ionogels showed negligible shrinkage and stable electrochemical performance at 100 °C due to higher porosity and wettability of the polymer strands by the IL. The work further ventured into assessment of the state of IL molecules in the pores of sPS gel. The results revealed that the melting point of IL molecules was elevated due to confinement of the IL molecules in the sPS network. At room temperature, the non-bonded cation-cation through-space correlation was obtained for confined IL, while such correlation was absent in bulk IL. The information on ion aggregation and the effect of confinement can guide proper selection of polymer-IL pair for electrochemical membranes. The results of investigation on a composite solid polymer electrolyte (CSPE) membranes is presented in chapter VI. A photocurable plasticized solid polymer electrolyte formulation was incorporated in porous sPS gel with the aim of increasing the mechanical strength of the neat SPE. The all solid-state CSPE was characterized using TGA and DSC to assess their thermal stability. Mechanical strength of the composite materials showed a six-fold increase in tensile strength and much higher storage modulus compared to neat SPE. The DSC and XRD data analysis showed no change in the crystalline structure of electrolyte in CSPE, thus retaining the amorphous polymeric domains resulting in high ionic mobility at room temperature (4.3 x 10−4 S/cm). These flexible materials were tested as electrolyte membranes in Li-ion batteries using LiFePO4 half cells. It was observed that the electrochemical window of CSPE expanded up to 5V due to the presence of the sPS matrix. The last part of the thesis covers the strategies for reduction of hysteresis loss in filled elastomeric compounds by increased affinity between filler and polymer chain via coupling agent. The role of novel graft copolymer poly(butadiene-graft-pentafluorostyrene) (PB-g-PPFS) as a physical coupling agent between carbon black and styrene butadiene rubber (SBR) was studied. Physical arene-perfluoroarene bonding between carbon black and PPFS grafts led to reduced filler-filler networking. The presence of arene-perfluoroarene bonding was confirmed by analysis of Raman spectra and TEM images. Filler flocculation and Payne effect analysis showed that the addition of the coupling agent resulted in increased filler dispersion and reduced energy dissipation. The viscoelastic loss was reduced by as much as 12 % as compared to control material due to improved filler-rubber affinity promoted by the coupling agent.

Download or read book Advances in Lithium Ion Batteries written by Walter van Schalkwijk and published by Springer Science & Business Media. This book was released on 2007-05-08 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the decade since the introduction of the first commercial lithium-ion battery research and development on virtually every aspect of the chemistry and engineering of these systems has proceeded at unprecedented levels. This book is a snapshot of the state-of-the-art and where the work is going in the near future. The book is intended not only for researchers, but also for engineers and users of lithium-ion batteries which are found in virtually every type of portable electronic product.

Download or read book Lithium Dendrite Growth Through Solid Polymer Electrolyte Membranes written by Katherine Joann Harry and published by . This book was released on 2016 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The next generation of rechargeable batteries must have significantly improved gravimetric and volumetric energy densities while maintaining a long cycle life and a low risk of catastrophic failure. Replacing the conventional graphite anode in a lithium ion battery with lithium foil increases the theoretical energy density of the battery by more than 40%. Furthermore, there is significant interest within the scientific community on new cathode chemistries, like sulfur and air, that presume the use of a lithium metal anode to achieve theoretical energy densities as high as 5217 W·h/kg. However, lithium metal is highly unstable toward traditional liquid electrolytes like ethylene carbonate and dimethyl carbonate. The solid electrolyte interphase that forms between lithium metal and these liquid electrolytes is brittle which causes a highly irregular current distribution at the anode, resulting in the formation of lithium metal protrusions. Ionic current concentrates at these protrusions leading to the formation of lithium dendrites that propagate through the electrolyte as the battery is charged, causing it to fail by short-circuit. The rapid release of energy during this short-circuit event can result in catastrophic cell failure. Polymer electrolytes are promising alternatives to traditional liquid electrolytes because they form a stable, elastomeric interface with lithium metal. Additionally, polymer electrolytes are significantly less flammable than their liquid electrolyte counterparts. The prototypical polymer electrolyte is poly(ethylene oxide). Unfortunately, when lithium anodes are used with a poly(ethylene oxide) electrolyte, lithium dendrites still form and cause premature battery failure. Theoretically, an electrolyte with a shear modulus twice that of lithium metal could eliminate the formation of lithium dendrites entirely. While a shear modulus of this magnitude is difficult to achieve with polymer electrolytes, we can greatly enhance the modulus of our electrolytes by covalently bonding the rubbery poly(ethylene oxide) to a glassy polystyrene chain. The block copolymer phase separates into a lamellar morphology yielding co-continuous nanoscale domains of poly(ethylene oxide), for ionic conduction, and polystyrene, for mechanical rigidity. On the macroscale, the electrolyte membrane is a tough free-standing film, while on the nanoscale, ions are transported through the liquid-like poly(ethylene oxide) domains. Little is known about the formation of lithium dendrites from stiff polymer electrolyte membranes given the experimental challenges associated with imaging lithium metal. The objective of this dissertation is to strengthen our understanding of the influence of the electrolyte modulus on the formation and growth of lithium dendrites from lithium metal anodes. This understanding will help us design electrolytes that have the potential to more fully suppress the formation of dendrites yielding high energy density batteries that operate safely and have a long cycle life. Synchrotron hard X-ray microtomography was used to non-destructively image the interior of lithium-polymer-lithium symmetric cells cycled to various stages of life. These experiments showed that in the early stages of lithium dendrite development, the bulk of the dendritic structure was inside of the lithium electrode. Furthermore, impurity particles were found at the base of the lithium dendrites. The portion of the lithium dendrite protruding into the electrolyte increased as the cell approached the end of life. This imaging technique allowed for the first glimpse at the portion of lithium dendrites that resides inside of the lithium electrode. After finding a robust technique to study the formation and growth of lithium dendrites, a series of experiments were performed to elucidate the influence of the electrolyte's modulus on the formation of lithium dendrites. Typically, electrochemical cells using a polystyrene - block¬ - poly(ethylene oxide) copolymer electrolyte are operated at 90 °C which is above the melting point of poly(ethylene oxide) and below the glass transition temperature of polystyrene. In these experiments, the formation of dendrites in cells operated at temperatures ranging from 90 °C to 120 °C were compared. The glass transition temperature of polystyrene (107 °C) is included in this range resulting in a large change in electrolyte modulus over a relatively small temperature window. The X-ray microtomography experiments showed that as the polymer electrolyte shifted from a glassy state to a rubbery state, the portion of the lithium dendrite buried inside of the lithium metal electrode decreased. These images coupled with electrochemical characterization and rheological measurements shed light on the factors that influence dendrite growth through electrolytes with viscoelastic mechanical properties. Next, the morphology of lithium dendrites formed upon many charge and discharge cycles were compared to the morphology of those grown upon a continuous charge using a combination of X-ray and electron microscopy techniques. When cycled, the lithium dendrite morphology consisted of multiple interconnected lithium globules that amassed to form a structure that punctured the electrolyte causing the cell to fail by short-circuit. When charge is passed in only one direction until the samples fails by short-circuit, the dendrite morphology is markedly different. Instead of observing a multi-globular morphology, a single lithium-filled globule encased in a polymer sac expands until it touches the counter-electrode. These blunt structures formed in solid polymer electrolytes are in stark contrast to the needle-like morphologies observed in lithium dendrites formed in liquid electrolyte systems. Time-resolved hard X-ray microtomography was used to monitor the internal structure of a symmetric lithium-polymer cell during galvanostatic polarization. The microtomography images were used to determine the local rate of lithium deposition, i.e. local current density, in the vicinity of a dendrite growing through the electrolyte. Measurements of electrolyte displacement enabled estimation of local stresses in the electrolyte. At early times, the current density was maximized at the dendrite tip, as expected from simple current distribution arguments. At later times, the current density was maximized at the dendrite perimeter. We show that this phenomenon is related to the local stress fields that arise as the electrolyte is deformed. The local current density, normalized for the radius of curvature, decreases with increasing compressive stresses at the lithium-polymer interface. To our knowledge, our study provides the first direct measurement showing the influence of local mechanical stresses on the deposition kinetics at lithium metal electrodes.