Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Development Of Electrodes Based On Wetspun Graphene For Flexible Rechargeable Lithium Batteries
Download Development Of Electrodes Based On Wetspun Graphene For Flexible Rechargeable Lithium Batteries full books in PDF, epub, and Kindle. Read online Development Of Electrodes Based On Wetspun Graphene For Flexible Rechargeable Lithium Batteries ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Development of Electrodes Based on Wetspun Graphene for Flexible Rechargeable Lithium Batteries by : Woon Gie Chong
Download or read book Development of Electrodes Based on Wetspun Graphene for Flexible Rechargeable Lithium Batteries written by Woon Gie Chong and published by . This book was released on 2018 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Graphene Network Scaffolded Flexible Electrodes—From Lithium to Sodium Ion Batteries by : Dongliang Chao
Download or read book Graphene Network Scaffolded Flexible Electrodes—From Lithium to Sodium Ion Batteries written by Dongliang Chao and published by Springer. This book was released on 2018-12-11 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on deformable and wearable electronics has promoted an increasing demand for next-generation power sources with high energy/power density that are low cost, lightweight, thin and flexible. One key challenge in flexible electrochemical energy storage devices is the development of reliable electrodes using open-framework materials with robust structures and high performance. Based on an exploration of 3D porous graphene as a flexible substrate, this book constructs free-standing, binder-free, 3D array electrodes for use in batteries, and demonstrates the reasons for the research transformation from Li to Na batteries. It incorporates the first principles of computational investigation and in situ XRD, Raman observations to systematically reveal the working mechanism of the electrodes and structure evolution during ion insertion/extraction. These encouraging results and proposed mechanisms may accelerate further development of high rate batteries using smart nanoengineering of the electrode materials, which make “Na ion battery could be better than Li ion battery” possible.
Book Synopsis Development of Flexible Lithium Sulfur Batteries Based on Laser-induced Graphene by : Ngai Yan Lau
Download or read book Development of Flexible Lithium Sulfur Batteries Based on Laser-induced Graphene written by Ngai Yan Lau and published by . This book was released on 2018 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emerging technologies have become increasingly advanced with flexible components and are integrated into various interfaces, finding themselves in applications such as rollable displays, wearable technologies and e-textiles. As a result, there is a need for a fully flexible battery with higher energy storage capacity that is simple to fabricate while being cost effective. While most commercially available flexible and thin-film batteries are formed through microfabrication techniques and other high capital cost methods, there is a need to explore higher energy density chemistries and determine a more cost-effective route to fabricating such batteries for the mass production and wide-spread use of flexible batteries. The work in this thesis focused on the adaptation of a recently reported laser-scribing method to produce interdigitated electrodes from laser-induced graphene (LIG) towards the development of flexible lithium-sulfur (LiS) batteries. A proof of concept was demonstrated for this graphene material through sequentially patterning and depositing the active materials, sulfur and lithium, into the LIG fingers. A novel technique to introduce sulfur into carbon-based fingers was presented by the heterogeneous nucleation of sulfur crystals followed by their melting to wet the graphene and uniformly distribute within the porous network formed. In order introduce a dense lithium metal anode onto the porous substrate, silver nanoparticles were used as seeds for electrodeposition and a reverse pulse plating (RPP) technique was also utilized to reduce the lithium protrusions that would eventually form dendrites and high irreversible capacity loss due to the high surface area for solid electrolyte interface (SEI) formation. Initial cycling displayed energy densities that exceeded lithium-ion microbatteries and thin-film batteries fabricated through microfabrication at almost 200 mWh/cm3. However, the obtainable discharge capacities faded at the second cycle, suggesting a significant irreversible source of capacity loss. It was then determined the source to be a likely unstable solid electrolyte interphase (SEI) at the anode of the battery. Additionally, there was the finding of a prominent presence of macropores within the electrodes leading to an agglomeration of insulating sulfur within the pores that cannot be utilized in cycling. The combination of two of the major conclusions from the initial proof of concept propelled the investigations of improving the defectiveness of the LIG and control over the LIG structure as well as Li plating efficiency on various carbons in different electrolytes. From the studies on LIG structure control, it was found that a lower power led to a reduced flux of gas evolution during a reduced local temperature induction upon laser irradiation. Thus, the formed electrodes are typically more dense, possessing a higher surface area with a reduced volume. Although the electrodes become less conductive with a reduced power, the conductivity can be improved, and the graphene annealed through several laser passes or the defocusing of the laser beam. In the Li plating study, ether-based electrolytes were found to be detrimental to the cycling of plated lithium on the carbon electrodes, regardless of whether it was on a hard carbon with more sp3 regions or a soft carbon with mainly sp2 regions. This is because of solvent co-intercalation during lithium insertion and also the unstable SEI formed. Graphite, the soft carbon, performs best as a Li plating substrate in a carbonate-based electrolyte with a LiTFSI salt, while carbonized poly(furfuryl alcohol) (CPFA), a hard carbon, performs best in a carbonate-based electrolyte with a LiClO4. While further research is needed to understand how to control the carbonization of the PI to achieve a level of “hardness” or “softness” in the carbon, the results presented in this work contribute to the understanding of the novel LIG material in addition to the field of lithium electroplating onto substrates for the reduction of excess lithium use. Finally, the successful demonstration of a proof of concept of LiS batteries from LIG in an open architecture makes it possible for a number of future in operando analyses and characterizations of the LiS battery chemistry towards their commercialization.
Book Synopsis Development of Flexible, Carbon-based Electrochemical Energy Storage Electrodes by : Ricky Tjandra
Download or read book Development of Flexible, Carbon-based Electrochemical Energy Storage Electrodes written by Ricky Tjandra and published by . This book was released on 2019 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research into energy storage and conversion technologies has skyrocketed within the past few decades, motivated by the increased energy demands of our society and the threat of depleting energy sources. One of the exciting forefronts of energy storage research is the development of flexible electrochemical energy storage systems. This area of active research is fueled by the popularity of the Internet-of-Things (IOT), smart wearables/clothing and flexible electronics. A distinct lack of commercially available electrochemical energy storage options that can be flexed, bent, stretched and twisted is currently available to power these devices. Instead, most of today's flexible electronic and wearables rely on rigid cell formats such as cylindrical and prismatic cells. The problem of flexible energy storage devices can be broken down into 2 deficiencies: the lack of flexible electrodes that can match the performance of their rigid counterparts and the lack of high-performance solid-state electrolytes. Carbon-based materials, especially nanoscale materials such as graphene, are a potential solution to this problem due to their electronic conductivity, relative abundance, energy storage capabilities, and ability to be used in all parts of the energy storage system. All the work presented in this thesis involves the development and applications of carbon-based materials for flexible electrochemical energy storage systems. This thesis will explore two different pathways of achieving flexible electrodes based on carbon-based materials: - Replacement of non-flexible metal foil current collectors using flexible carbon-based current collectors - Elimination of current collectors and binders by using carbon-based, free-standing materials Firstly, this thesis will explore the use of carbon cloth as a substrate for a novel TiO2 nanocrystal material for use as an anode in flexible lithium-ion supercapacitors. Although lithium-ion supercapacitors are the focus of this study, the same composite material can also be used as an anode in traditional lithium-ion batteries. The resulting carbon cloth/TiO2 composite is able to withstand 100 flexion cycles while still retaining its energy storage capabilities, showing the advantage of the carbon cloth as a substrate when compared to traditional metal foils. The composite is also successfully integrated into a flexible pouch cell that delivers an excellent reversible capacity of 270 mAh g-1. This work establishes that carbon cloth can be used to replace metal foils as a flexible current collector without sacrificing electrochemical performance. Secondly, this thesis explores the use of a nitrogen-rich carbon foam based on the carbonization of melamine formaldehyde and graphene oxide for use in lithium-ion hybrid capacitors. The foam presented here can be used as-is as a flexible, free-standing, binder-free anode for lithium-ion hybrid capacitors/batteries. Furthermore, the foam can also be used as a 3-dimensional current collector for other active materials both in the anode and the cathode, which demonstrates its versatility for electrochemical energy storage systems. An all-carbon based lithium-ion hybrid supercapacitor has been fabricated using the foam as both an active material for the anode and the current collector for the activated carbon cathode. The cell shown in this chapter achieved an energy density of 40 Wh kg-1 which is superior to that reported in the literature that are based purely on carbon materials. The work presents a novel carbon-based flexible electrode material and concept device that also enables the removal of binders and current collectors from traditional batteries and supercapacitors, bringing us one step closer to achieving a fully flexible electrochemical energy storage system. Finally, graphene quantum dots (GQDs) have been synthesized using a simple peroxide-assisted method. The GQDs are then electrodeposited onto carbon cloth to make an all-carbon, binder-free, flexible electrode for supercapacitors. This work builds off the TiO2/carbon cloth composite by replacing the TiO2 with a carbon-based nanomaterial. Presently reported research has involved the use of GQDs either in conjunction with another active material or used as an active material on rigid, planar substrates. We have shown that GQDs can function as a stand-alone active material for EDLC capacitors. At the time of writing, this work shows the first such use of GQDs on a non-planar, flexible substrate for supercapacitors. All the work in this thesis centers around the use of carbon-based materials and their composites towards the development of flexible electrodes for lithium-ion batteries, supercapacitors and their hybrids. This thesis provides insights into the viability of using various carbon-based materials in different aspects of flexible electrodes and provides a basis for future investigations into this topic.
Book Synopsis Graphene-based Composites for Electrochemical Energy Storage by : Jilei Liu
Download or read book Graphene-based Composites for Electrochemical Energy Storage written by Jilei Liu and published by Springer. This book was released on 2017-01-07 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the synthesis and characterization of various carbon allotropes (e.g., graphene oxide/graphene, graphene foam (GF), GF/carbon nanotube (CNT) hybrids) and their composites for electrochemical energy storage applications. The coverage ranges from materials synthesis to electrochemical analysis, to state-of-the-art electrochemical energy storage devices, and demonstrates how electrochemical characterization techniques can be integrated and applied in the active materials selection and nanostructure design process. Readers will also discover the latest findings on graphene-based electrochemical energy storage devices including asymmetric supercapacitors, lithium ion batteries and flexible Ni/Fe batteries. Given the unique experimental procedures and methods, the systematic electrochemical analysis, and the creative flexible energy storage device design presented, the thesis offers a valuable reference guide for researchers and newcomers to the field of carbon-based electrochemical energy storage.
Book Synopsis Graphene and Carbon Nanotubes for Advanced Lithium Ion Batteries by : Stelbin Peter Figerez
Download or read book Graphene and Carbon Nanotubes for Advanced Lithium Ion Batteries written by Stelbin Peter Figerez and published by CRC Press. This book was released on 2018-12-07 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title covers the fundamentals of carbon nanomaterials in a logical and clear manner to make concepts accessible to researchers from different disciplines. It summarizes in a comprehensive manner recent technological and scientific accomplishments in the area of carbon nanomaterials and their application in lithium ion batteries The book also addresses all the components anodes, cathodes and electrolytes of lithium ion battery and discusses the technology of lithium ion batteries that can safely operate at high temperature.
Book Synopsis Development on High Energy Lithium-ion Batteries Based on Silicon Electrodes by : Qianye Huang
Download or read book Development on High Energy Lithium-ion Batteries Based on Silicon Electrodes written by Qianye Huang and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Graphene written by Zhaoping Liu and published by CRC Press. This book was released on 2014-11-24 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suitable for readers from broad backgrounds, Graphene: Energy Storage and Conversion Applications describes the fundamentals and cutting-edge applications of graphene-based materials for energy storage and conversion systems. It provides an overview of recent advancements in specific energy technologies, such as lithium ion batteries, supercapacitors, fuel cells, solar cells, lithium sulfur batteries, and lithium air batteries. It also considers the outlook of industrial applications in the near future. Offering a brief introduction to the major synthesis methods of graphene, the text details the latest academic and commercial research and developments, covering all potential avenues for graphene’s use in energy-related areas.
Book Synopsis Phosphate Based Cathodes and Reduced Graphene Oxide Composite Anodes for Energy Storage Applications by : Abdulrahman Shahul Hameed
Download or read book Phosphate Based Cathodes and Reduced Graphene Oxide Composite Anodes for Energy Storage Applications written by Abdulrahman Shahul Hameed and published by Springer. This book was released on 2016-07-30 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis outlines the investigation of various electrode materials for Li-ion battery (LIB) applications. Li-ion batteries are widely used in various portable electronic devices owing to their compactness, light weight, longer life, design flexibility and environment friendliness. This work describes the detailed synthesis and structural studies of various novel phosphate based cathode materials and reduced graphene oxide (rGO) composites as anode materials. Their electrochemical characterization as electrode for LIBs has been investigated in detail. The thesis also includes a comprehensive introduction for non-specialists in this field. The research could benefit and will appeal to scientists, especially new researchers working in the field of energy storage.
Book Synopsis Development of Novel Nanomaterials Based on Silicon and Graphene for Lithium Ion Battery Applications by : Yuhai Hu
Download or read book Development of Novel Nanomaterials Based on Silicon and Graphene for Lithium Ion Battery Applications written by Yuhai Hu and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical energy storage is one of the important strategies to address the strong demand for clean energy. Rechargeable lithium ion batteries (LIBs) are one of the typical electrochemical devices and have been used in a great number of areas. Now, the challenge for the LIB research is to make the batteries carry higher energy density so as to fulfill the demand of the emerging markets, particularly, electric vehicles and portable smart electronics. In this regard, the present commercial anode material can not meet this requirement. Much effort is being made toward either exploring new morphologies of carbon materials or searching for new materials that possess high theoretical lithium ion storage capacities. Among these, graphene and silicon have been receiving rapidly increasing interest. As such, this Ph D research focused on two topics: (1) developing graphene-based freestanding materials used as anodes for LIBs, which will find potential applications in flexible LIBs; (2) developing cost-effective processes for mass production of low-dimensional nanostructured silicon with controlled morphologies from low-cost materials. The freestanding anodes include graphene papers, graphene-carbon nanotubes papers, graphene-MoS2 papers and graphene-Si nanowires papers. They exhibited very high mechanical strength. Their battery performances were highly dependent on the composites of the papers and the ratios of graphene to the guest component (e.g., Si), and graphene-Si nanowires papers exhibited the highest lithium-storage capacities of>1000 mA h g-1. The materials have high potential for use as freestanding anodes for LIBs. The related results are organized in Chapter 3-6 in this thesis. A catalyst-free etching process was developed to produce 1D silicon nanostructures (nanobelts and nanowires) from low-cost and metallurgical ferrosilicon alloys with relatively high yields. When used as an anode material, the 1D nanostructured silicon demonstrated reversible lithium storage capacity of 2600 mA h g-1, high rate capability and relatively stable cyclic performances in lab made Li-ion cells. This invention offers a method that is highly potential for low cost, mass production of 1D nanostructured silicon. The related results are organized in Chapter 7 in this thesis. Challenges and future research opportunities in the two areas were suggested.
Book Synopsis Advanced Silicon-based Electrodes for Rechargeable Lithium-ion Batteries by : Kun Feng
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.
Book Synopsis Development of the Flexible Graphene-Silicone Dry Electrode for Real-World BCI. by :
Download or read book Development of the Flexible Graphene-Silicone Dry Electrode for Real-World BCI. written by and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Nanostructured Polyaniline-based Electrode Materials for High-performance Supercapacitors by : Ali Khosrozadeh
Download or read book Development of Nanostructured Polyaniline-based Electrode Materials for High-performance Supercapacitors written by Ali Khosrozadeh and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical energy storage and conversion devices are among clean energy technologies that play an important role in overcoming global pollution. Supercapacitors (SCs) are an important class of energy storage devices owing to their fast charge-discharge rate, high power density, low maintenance, and long cycle life. They bridge the gap between conventional capacitors and rechargeable batteries and are most useful in applications that require a fast power boost and delivery. Polyaniline (PAni) is a promising conducting polymer with the advantages of high pseudocapacitance, environmental stability, low cost and ease of synthesis. However, there are few shortcomings that limit the practical application of PAni as an electrode material for SCs. PAni suffers from poor cycle life which considerably compromises the advantage of long cycle life of SCs over batteries. In addition, it is formidable to produce mechanically robust films from pristine PAni since it is a brittle material. To overcome the limitations of PAni, this thesis explores various approaches to construct a flexible PAni-based composite film by combining PAni with other nanomaterials. A low-cost PAni-based electrode for solid-state SCs is developed on the basis of PAni and acid-treated carbon particles. Later on, a new strategy to construct a flexible PAni-based electrode with an adjustable mass-loading of active materials is introduced. Cellulose is employed as a backbone for a composite film of PAni, reduced graphene oxide, and silver nanowires. In a similar approach, a flexible electrode for high-performance SCs is developed on basis of PAni, cellulose, graphite-based exfoliated graphite, and silver nano-particles. This strategy allows designing composite electrodes with large surface area and porosity, and adjustable energy and power densities. Another strategy to construct a flexible PAni-based electrode and address the poor cycle life of PAni is growing PAni on nanofibrous and cushiony substrates. A flexible electrode for SCs with a remarkable cycling stability is developed using electrospun polyurethane as a cushiony support for growing flower-like PAni. Moreover, a novel flexible electrode is constructed by growing PAni on graphene-coated cross-linked polyvinyl alcohol nanofibers. The as-prepared SC maintains its capacitive performance for 84k cycles of charge-discharge indicating an unprecedented cycling stability.
Book Synopsis Design of Graphene-based Structures for Capacitive Energy Storage by : Zhuangnan Li
Download or read book Design of Graphene-based Structures for Capacitive Energy Storage written by Zhuangnan Li and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercapacitors are the promising next-generation energy storage devices that bridge the gap between traditional capacitors and batteries, but still require their electrode material to be further developed. Here, this thesis aims at design and development of the graphene-based porous structures as the supercapacitor electrode for efficient electrochemical energy storage. Step-by-step research is carried out by firstly investigating the effect of graphene-oxide precursors, then enhancing the specific capacitance of a single electrode, and finally increasing the overall performance (in terms of the energy density and power density) at the entire device level. The details of these three main work in the PhD project are as follows: (1) Graphene-based materials are highly desirable for supercapacitors, but vary considerably in reported properties despite being prepared by similar procedures; therefore, a clear route to improve the performance is currently lacking. Here, a direct correlation between the initial oxidation of graphene-oxide precursors and final supercapacitor performance is demonstrated. Building on this significant understanding, the optimized three-dimensional graphene frameworks achieve a superior gravimetric capacitance of 330 F g-1 in an aqueous electrolyte. This extraordinary performance is also validated in various electrolytes at a device level. In a commercially used organic electrolyte, an excellent volumetric energy density of 51 Wh L-1 can be delivered, which significantly outperforms the state-of-the-art commercial carbon-based devices. Furthermore, solid-state supercapacitor with a gel electrolyte shows an impressive capacitance of 285 F g-1 with a rate capability of 79% at 20 A g-1 and capacitance retention of 93% after 20,000 cycles. This study presents a versatile design principle for engineering chemically derived graphene towards diverse applications in energy storage. (2) Graphene-oxide (GO) based porous structures are highly desirable for supercapacitors, as the charge storage and transfer can be enhanced by advancement in the synthesis. Here, this study presents an effective route of, first, synthesis of a three dimensional assembly of GO sheets in a spherical architecture by flash-freezing of GO dispersion, and then development of hierarchical porous graphene networks by facile thermal-shock reduction of GO spheres. Thus, this process leads to a superior gravimetric specific capacitance of ~306 F g−1 at 1.0 A g−1, with a capacitance retention of 93% after 10,000 cycles. The values represent a significant capacitance enhancement by 30"â€50% compared with the GO powder equivalent, and are among the highest reported for GO-based structures from different chemical reduction routes. Furthermore, a solid-state flexible supercapacitor is fabricated by constructing the porous graphene networks with polymer gel electrolyte, exhibiting an excellent areal specific capacitance of 220 mF cm−2 at 1.0 mA cm−2 with exceptional cyclic stability. The work reveals the synthetic and further processing effects of GO-based materials to enhance their structure-performance relationships for capacitive energy storage. (3) Supercapacitors have shown extraordinary promise for miniaturized electronics and electric vehicles, but are usually limited by electrodes with rather low volumetric performance largely due to the inefficient utilization of pores in charge storage. Herein, this study designs a freestanding graphene laminate film electrode with highly efficient pore-utilization for compact capacitive energy storage. The interlayer spacing of this film can be precisely adjusted, which enables a tunable porosity. By systematically tailoring the pore size for the electrolyte ions, pores are utilized optimally and thereby the volumetric capacitance is maximized. Consequently, the fabricated supercapacitor delivers a record-high stack volumetric energy density of 88.1 Wh L-1 in an ionic liquid electrolyte, representing a critical breakthrough for optimizing the porosity towards compact energy storage. Moreover, the optimized film electrode is assembled into an ionogel-based all-solid-state flexible smart device with multiple optional output and superior stability, demonstrating enormous potential as portable power supply in practical applications.
Book Synopsis Recent Advancements in Polymeric Materials for Electrochemical Energy Storage by : Ram K. Gupta
Download or read book Recent Advancements in Polymeric Materials for Electrochemical Energy Storage written by Ram K. Gupta and published by Springer Nature. This book was released on 2023-07-15 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the current, state-of-the-art knowledge, fundamental mechanisms, design strategies, and future challenges in electrochemical energy storage devices using polymeric materials. It looks into the fundamentals and working principles of electrochemical energy devices such as supercapacitors and batteries and explores new approaches for the synthesis of polymeric materials and their composites to broaden the vision for researchers to explore advanced materials for electrochemical energy applications. All the chapters are written by leading experts in these areas making it suitable as a reference for students as well as provide new directions to researchers and scientists working in polymers, energy, and nanotechnology.
Book Synopsis Development of Advanced Electrode Materials for Use in Rechargeable Lithium Batteries by : Scott Andrew Needham
Download or read book Development of Advanced Electrode Materials for Use in Rechargeable Lithium Batteries written by Scott Andrew Needham and published by . This book was released on 2007 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fabrication and Simulation of Semi-solid Electrodes for Flexible Lithium-ion Batteries by : Waleed Zakri
Download or read book Fabrication and Simulation of Semi-solid Electrodes for Flexible Lithium-ion Batteries written by Waleed Zakri and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flexible Li-ion batteries (LIBs) have strong forthcoming consumer market demand for use in different wearable electronic devices, flexible smart electronics, roll-up displays, electronic shelf labels, active radio-frequency identification tags, and implantable medical devices. This market demand necessitates research and development of these batteries in order to fulfill the energy and power requirements of these next-generation devices. In this study, the performance of semi-solid electrodes, which consists of active and conductive additive materials suspended in liquid electrolyte, for flexible LIBs is investigated through experiment and modeling. For the semi-solid graphite anode three different conductive additive materials of Super C45, Super P, and Ketjenblack are investigated. For the liquid electrolyte, which is mixed with graphite and conductive additive materials, lithium hexafluorophosphate salt (LiPF6) was dissolved in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). Several semi-solid graphite anodes with different compositions were fabricated and tested during the study. Over 65% of the specific discharge capacity to the theoretical capacity was achieved for the optimal composition of an anode. The semi-solid lithium cobalt oxide (LCO) cathode was also fabricated and tested simultaneously in the same lab. Subsequently, a full cell for a flexible LIB was fabricated based on the performances of the optimum LCO cathode and graphite anode half cells; then, the full cell was tested using galvanostatic measurements. A specific discharge capacity of over 60 mAh/g based on cathode mass was obtained when the cell was charged and discharged in the voltage range of 2.5-4.2V at a C-rate of C/40.In order to reduce the number of experiments and to achieve the desired energy capacity of the battery, a mathematical model was developed. This model is a multiphysics three-dimensional heterogeneous model. All necessary transport phenomena including the charge and mass transfer and electrochemical reactions are considered at continuum mechanics level in the model. COMSOL Multiphysics software is used to solve governing equations numerically using a finite element method. This model is for a half-cell simulation, and by using experimental results obtained in the lab, this model separately validates both a semi-solid LCO cathode and a semi-solid graphite anode. To achieve the full-cell model, the developed half-cell models were enhanced using the same transport phenomena equations at a continuum mechanics level. Anode and cathode electrodes were modeled to serve as active components of the full-cell while the liquid electrolyte could pass through the void between the particles. The results confirm that both the fabricated and computer simulated full-cell for the flexible LIB are in good agreement with less than 5% error at the end of discharge. After developing the full-cell model, the effect of the cell temperature, the separator thickness, electrodes mass, the discharge current rate, and the initial concentration of hexafluorophosphate salt (LiPF6) in the electrolyte were examined. Lower values of discharge capacity were observed with higher C-rates or larger separator thickness. The cell was also simulated at different cell temperatures confirming that capacity is not strongly affected by temperature, as minor changes were obtained. In order to maximize the capacity, the cell with high anode electrode mass had a higher specific discharge capacity when the cell was simulated at different electrode mass ratio. These simulation results are necessary to save both time and cost of materials, along with components used for fabricating semi-solid electrodes. Overall, the results obtained confirm that the fabrication of a relatively high-energy density of flexible primary LIB, based on the concept of semi-solid electrodes, is feasible and can be used effectively for low power demand applications.
