Hybrid Core Shell Nanowire Electrodes Utilizing Vertically Aligned Carbon Nanofiber Arrays For High Performance Energy Storage

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Hybrid Core Shell Nanowire Electrodes Utilizing Vertically Aligned Carbon Nanofiber Arrays For High Performance Energy Storage

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Author : Steven Arnold Klankowski
language : en
Publisher:
Release Date : 2015

Hybrid Core Shell Nanowire Electrodes Utilizing Vertically Aligned Carbon Nanofiber Arrays For High Performance Energy Storage written by Steven Arnold Klankowski and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.

Nanostructured electrode materials for electrochemical energy storage systems have been shown to improve both rate performance and capacity retention, while allowing considerably longer cycling lifetime. The nano-architectures provide enhanced kinetics by means of larger surface area, higher porosity, better material interconnectivity, shorter diffusion lengths, and overall mechanical stability. Meanwhile, active materials that once were excluded from use due to bulk property issues are now being examined in new nanoarchitecture. Silicon was such a material, desired for its large lithium-ion storage capacity of 4,200 mAh g−1 and low redox potential of 0.4 V vs. Li/Li; however, a ~300% volume expansion and increased resistivity upon lithiation limited its broader applications. In the first study, the silicon-coated vertically aligned carbon nanofiber (VACNF) array presents a unique core-shell nanowire (NW) architecture that demonstrates both good capacity and high rate performance. In follow-up, the Si-VACNFs NW electrode demonstrates enhanced power rate capabilities as it shows excellent storage capacity at high rates, attributed to the unique nanoneedle structure that high vacuum sputtering produces on the three-dimensional array. Following silicon's success, titanium dioxide has been explored as an alternative highrate electrode material by utilizing the dual storage mechanisms of Li insertion and pseudocapacitance. The TiO2-coated VACNFs shows improved electrochemical activity that delivers near theoretical capacity at larger currents due to shorter Li+ diffusion lengths and highly effective electron transport. A unique cell is formed with the Si-coated and TiO2-coated electrodes place counter to one another, creating the hybrid of lithium ion battery-pseudocapacitor that demonstrated both high power and high energy densities. The hybrid cell operates like a battery at lower current rates, achieving larger discharge capacity, while retaining one-third of that capacity as the current is raised by 100-fold. This showcases the VACNF arrays as a solid platform capable of assisting lithium active compounds to achieve high capacity at very high rates, comparable to modern supercapacitors. Lastly, manganese oxide is explored to demonstrate the high power rate performance that the VACNF array can provide by creating a supercapacitor that is highly effective in cycling at various high current rates, maintaining high-capacity and good cycling performance for thousands of cycles.

Advances In Electrochemical Energy Materials

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Author : Zhaoyang Fan
language : en
Publisher: MDPI
Release Date : 2020-04-02

Advances In Electrochemical Energy Materials written by Zhaoyang Fan and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-04-02 with Science categories.

Electrochemical energy storage is becoming essential for portable electronics, electrified transportation, integration of intermittent renewable energy into grids, and many other energy and power applications. The electrode materials and their structures, in addition to the electrolytes, play key roles in supporting a multitude of coupled physicochemical processes that include electronic, ionic, and diffusive transport in electrode and electrolyte phases, electrochemical reactions and material phase changes, as well as mechanical and thermal stresses, thus determining the storage energy density and power density, conversion efficiency, performance lifetime, and system cost and safety. Different material chemistries and multiscale porous structures are being investigated for high performance and low cost. The aim of this Special Issue is to report the recent advances in materials used in electrochemical energy storage that encompass supercapacitors and rechargeable batteries.

Materials In Energy Conversion Harvesting And Storage

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Author : Kathy Lu
language : en
Publisher: John Wiley & Sons
Release Date : 2014-09-22

Materials In Energy Conversion Harvesting And Storage written by Kathy Lu and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-09-22 with Technology & Engineering categories.

First authored book to address materials' role in the quest for the next generation of energy materials Energy balance, efficiency, sustainability, and so on, are some of many facets of energy challenges covered in current research. However, there has not been a monograph that directly covers a spectrum of materials issues in the context of energy conversion, harvesting and storage. Addressing one of the most pressing problems of our time, Materials in Energy Conversion, Harvesting, and Storage illuminates the roles and performance requirements of materials in energy and demonstrates why energy materials are as critical and far-reaching as energy itself. Each chapter starts out by explaining the role of a specific energy process in today’s energy landscape, followed by explanation of the fundamental energy conversion, harvesting, and storage processes. Well-researched and coherently written, Materials in Energy Conversion, Harvesting, and Storage covers: The availability, accessibility, and affordability of different energy sources Energy production processes involving material uses and performance requirements in fossil, nuclear, solar, bio, wind, hydrothermal, geothermal, and ocean energy systems Issues of materials science in energy conversion systems Issues of energy harvesting and storage (including hydrogen storage) and materials needs Throughout the book, illustrations and images clarify and simplify core concepts, techniques, and processes. References at the end of each chapter serve as a gateway to the primary literature in the field. All chapters are self-contained units, enabling instructors to easily adapt this book for coursework. This book is suitable for students and professors in science and engineering who look to obtain comprehensive understanding of different energy processes and materials issues. In setting forth the latest advances and new frontiers of research, experienced materials researchers and engineers can utilize it as a comprehensive energy material reference book.

Conducting Polymers Based Energy Storage Materials

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Author : Dr Inamuddin
language : en
Publisher: CRC Press
Release Date : 2019-12-10

Conducting Polymers Based Energy Storage Materials written by Dr Inamuddin and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-12-10 with Science categories.

Conducting polymers are organic polymers which contain conjugation along the polymer backbone that conduct electricity. Conducting polymers are promising materials for energy storage applications because of their fast charge–discharge kinetics, high charge density, fast redox reaction, low-cost, ease of synthesis, tunable morphology, high power capability and excellent intrinsic conductivity compared with inorganic-based materials. Conducting Polymers-Based Energy Storage Materials surveys recent advances in conducting polymers and their composites addressing the execution of these materials as electrodes in electrochemical power sources. Key Features: Provides an overview on the conducting polymer material properties, fundamentals and their role in energy storage applications. Deliberates cutting-edge energy storage technology based on synthetic metals (conducting polymers) Covers current applications in next-generation energy storage devices. Explores the new aspects of conducting polymers with processing, tunable properties, nanostructures and engineering strategies of conducting polymers for energy storage. Presents up-to-date coverage of a large, rapidly growing and complex conducting polymer literature on all-types electrochemical power sources. This book is an invaluable guide for students, professors, scientists, and R&D industrial specialists working in the field of advanced science, nanodevices, flexible electronics, and energy science.

Graphene Network Scaffolded Flexible Electrodes From Lithium To Sodium Ion Batteries

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Author : Dongliang Chao
language : en
Publisher: Springer
Release Date : 2018-12-11

Graphene Network Scaffolded Flexible Electrodes From Lithium To Sodium Ion Batteries written by Dongliang Chao and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-12-11 with Technology & Engineering categories.

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.

Advanced Carbon Nanofiber Materials For Electrochemical Energy Storage Devices

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Author : Richa Singhal
language : en
Publisher:
Release Date : 2016

Advanced Carbon Nanofiber Materials For Electrochemical Energy Storage Devices written by Richa Singhal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Carbon nanofibers categories.

Environmental concerns and rising demand for portable electronics and electric vehicles have stimulated the development of energy storage devices such as batteries and supercapacitors, towards higher energy density and power density, which significantly depend on the advancement of new materials used in these devices. Most studies in the literature utilize noble metals as catalysts, complex fabrication procedures, which are not easily scalable. Moreover, these techniques fabricate powder-based materials, which have to be blended with electrically insulating polymeric binders and coated onto conductive substrates to be utilized in a commercial system. Thus, development of nanostructured advanced energy storage materials with high stability, optimum pore structure/morphology, binder-free characteristic, and high catalytic activity is challenging and essential. This dissertation focuses on synthesis and understanding process-structure-performance correlation of binder-free carbon nanofiber-based advanced electrodes for applications in various energy storage devices. Carbon nanofibers (CNFs) are excellent candidates for application as electrodes in electrochemical energy storage (EES) devices because of their unique properties such as high mechanical strength, high electrical and thermal conductivities, high chemical stability, flexibility, and high specific surface area. Electrospinning is a simple and versatile fiber formation technique using a strong electric field to pull or thin out a polymer solution or melt jet forming ultrathin fibers with diameters in the range of 50–500 nm. This continuous fiber-formation technique inherently forms a free-standing non-woven fiber mat, thus, potentially allowing their direct application without the addition of any binders. Carbon nanofiber electrodes fabricated in this work are free-standing with a continuous interconnected network providing fast ion-diffusion as well as fast transport of electrons within the network, a characteristic essential for efficient energy storage, also allowing it to be directly used in any EES system without any further processing. Advanced carbon nanofibers with controlled pore architectures and enhanced functionalities were fabricated and characterized as cost-effective and performance-effective electrodes for supercapacitors, lithium-sulfur, and lithium-air batteries. Each of these EES systems is at a different stage of development and has different requirements of the materials used in it. Thus, studies were conducted focused on the issues to be addressed in each of these areas and varied carbon nanofiber based electrodes were synthesized and studied for each application. Chapter 1 provides the introduction to electrochemical energy storage systems, their working operation, and challenges associated with them, the motivation of using carbon nanofibers as electrodes in these systems and a summary of the dissertation. Chapter 2 discusses a novel technique towards introducing pseudocapacitive functionalities on carbon nanofibers using a low-cost material, sodium chloride, for application in supercapacitors. Chapter 3 includes the study on free-standing carbon nanofibers with controlled morphologies as an interlayer in lithium-sulfur cells, demonstrating improved discharge capacity and cycle life. Chapter 4 comprises of the investigation of cobalt nanoparticles embedded porous carbon nanofibers as efficient bifunctional catalysts for both oxygen reduction and oxygen evolution reactions (ORR/OER) and as an efficient cathode for lithium-oxygen batteries.

Carbon Nanotube Films For Energy Storage Applications

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Author : Alina Kozinda
language : en
Publisher:
Release Date : 2014

Carbon Nanotube Films For Energy Storage Applications written by Alina Kozinda and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.

With the rising demands for small, lightweight, and long-lasting portable electronics, the need for energy storage devices with both large power and large energy densities becomes vitally important. From their usage in hybrid electric vehicles to wearable electronics, supercapacitors and rechargeable batteries have been the focus of many previous works. Electrode materials with large specific surface areas can enhance the charging speed and total amount of stored energy. To this end, vertically self-aligned carbon nanotube (CNT) forests are well suited, as they possess outstanding electrical conductivities as well as high mechanical strength and large specific surface areas. In addition, forests of vertically aligned CNTs allow the ions within an electrolyte to pass freely between the individual CNTs from electrode to electrode. In order to minimize the system resistance of the battery or supercapacitor, a thin molybdenum current collector layer is deposited beneath catalyst of the CNT forest, thus ensuring that when the CNT forest grows from its substrate, each CNT has an innate connection to the current collector. This versatile CNT-Mo film architecture is used in this work as both supercapacitor as well as lithium-ion battery electrodes. It is desirable to have energy storage devices of adjustable shapes, such that they may conform to the shrinking form factors of modern portable electronics and mechanically flexible electrodes are an attractive prospect. The CNT-Mo film is shown here to easily release from its growth substrate, after which it may be placed onto a number of surfaces and topographies and densified. Two polymer films, Kapton® and ThermanoxTM, have been used as substrates for the demonstrations of flexible supercapacitor electrodes. Test results show that the attached active CNT-Mo film can withstand bending to at least as large an angle as 180°. The specific capacitance of a 5 mm by 5 mm area electrode in the K2SO4 aqueous electrolyte with an original CNT height of 40 micrometers is measured to be 7.0 mF/cm2. To further increase the surface area of the energy storage electrode, a thin, conformal coating of amorphous silicon is deposited onto a vertically aligned carbon nanotube forest using low pressure chemical vapor deposition (LPCVD). Various silicon film thickness depositions are tested as supercapacitor electrodes. A coating of 35 nm is shown to improve the specific capacitance by a factor of 2 as compared to a bare CNT electrode. For applications in which a larger operating voltage is desirable, the electrochemical window of the supercapacitor devices are increased by tailoring the electrolyte used. Using an ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate, or EMIM-BF4) improves the voltage window from 1 V (in aqueous electrolyte) to 4 V, yielding a power density from the range of 19 to 53 kW/kg. In addition, the CNT-Mo film is shown to outperform an activated carbon (AC) electrode in this ionic liquid in terms of volumetric capacitance by a factor of 12 (388 mF/cm3 versus 31 mF/cm3 for the CNT-Mo film and the AC, respectively). The cycling life of the film in ionic liquid at a number of current densities is also analyzed, and shown to be stable over 7000 charge-discharge cycles. Finally, the CNT-Mo film architecture is further utilized and tested as a lithium ion battery electrode. The high surface area, excellent CNT conductivities, and the extremely high lithium ion intercalation capacity of silicon all promise long-lived and energy-dense lithium ion electrodes. Preliminary results show high energy density of 4000 mAh/g initially. The value quickly drops to 600 mAh/g after 5 charge/discharge cycles and stay the same until failure after 15 cycles. Further studies into thinner silicon coatings and electrolyte selections may result in better performance and longer cycling life.

Carbon Nanotube Based Mems Energy Storage Devices

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Author : Yingqi Jiang
language : en
Publisher:
Release Date : 2011

Carbon Nanotube Based Mems Energy Storage Devices written by Yingqi Jiang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.

Carbon nanotube (CNT) forests have been utilized as electrodes in supercapacitors in this work for energy storage applications. High surface area to volume ratio, good electrical conductivity, and low contact resistance to a bottom metal electrode make CNT forests attractive as electrodes in supercapacitors. Several approaches have been investigated to improve the performances such as configurations, power and energy density of CNT-based supercapacitors, including the single layer architecture by utilizing interdigitated finger electrodes, pseudo capacitors based on electroplated nickel nanoparticles, ultra-long and densified CNT forests electrodes. Vertically aligned CNT forests have been synthesized using the thermal CVD process and their sheet and contact resistances have been characterized with four distinct methods: (1) the transfer length method (TLM), (2) the contact chain method, (3) the Kelvin method, and (4) the four point probe method. Experimental results show that CNT forests of 100μm in height and 100μm in width have a sheet resistance of about 100ohm/sq;. The specific contact resistance to a current collector is 5×10E4 ohm.μm2. Consistent results from these methods have been observed and less than 0.9% resistance deviations were measured after two months of open-air storage. In the first development stage, planar supercapacitors based on CNT forests electrodes with interdigitated finger shapes have been fabricated using a combination of Mo/Al/Fe metal stack layers to achieve dense growth of CNT with low resistance. The specific capacitances of the prototype electrodes were measured to be about 1000 times higher than those made of flat metal electrodes. Furthermore, charging/discharging experiments show over 92% energy storage efficiency and robust cycling stability. In the second development stage, CNT forests with embedded nickel nanoparticles have been used as electrodes for pseudo supercapacitors. A vacuum infiltration process is used in the electroplating process for the uniform deposition of 30-200nm in diameter nickel nanoparticles within the 80μm-high CNT forests. The measured specific capacitances are up to one order of magnitude higher than those CNT forests electrodes without nickel nanoparticles. No visual morphologic change was observed on nanoparticles after 1000 cycles of cyclic voltammetry tests. In the third development stage, ultra long CNT forests were synthesized using a water-assisted CVD process. Experimental results confirmed the capacitance increments were linearly proportion to the height increase of CNT forests with good long term stability. In the fourth development stage, a two-stage, self-aligned liquid densification process has applied on CNT forest to shrink the volume of CNT forests electrodes. By combining both mechanical bending and liquid densification, the height of CNT forest shrunk from 320μm to 21μm. Experimental results show self-aligned and continuous CNT films with preserved bottom contacts to the conductive metal layer. These densified CNT forests electrodes had similar total capacitances before and after the densification process while the volumetric specific capacitance increased from 1.07F/cm3 to 10.7F/cm3 because of the volume reductions.

Graphene Based Composites For Electrochemical Energy Storage

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Author : Jilei Liu
language : en
Publisher: Springer
Release Date : 2017-01-07

Graphene Based Composites For Electrochemical Energy Storage written by Jilei Liu and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-07 with Technology & Engineering categories.

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.

Wide Temperature Performing Electrolytes And Cost Effective Carbon Nanofiber Electrodes For High Performance Supercapacitors

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Author : Rangana Aloka Jayawickramage
language : en
Publisher:
Release Date : 2018

Wide Temperature Performing Electrolytes And Cost Effective Carbon Nanofiber Electrodes For High Performance Supercapacitors written by Rangana Aloka Jayawickramage and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Carbon nanofibers categories.

Supercapacitors, or electrochemical double layer capacitors, are energy storage devices that store energy electrostatically at the electrode-electrolyte interface. Supercapacitors exhibit higher power density and lower charge time than batteries, but they fall behind batteries in terms of energy density. Currently there is a considerable amount of research being carried out on increasing the energy density of supercapacitors. Also, supercapacitors are safer and more environmentally friendly than batteries. Supercapacitors have the potential of performing over a wide temperature window and can overtake batteries for low temperature applications. The performance of a supercapacitor can be enhanced by increasing the surface area and optimizing the pore size distribution of electrode materials and by using electrolytes with wide working potential window. Chapter 1 gives a basic introduction on supercapacitors and fabrication of electrode materials. It focuses on high surface area carbon nanofiber electrodes, thermal treatments and ionic liquid electrolytes. Chapter 2 describes a high performing ionic liquid electrolyte system which can perform from -50 oC to 100 oC. Chapter 3 reports on carbon nanofiber electrodes, derived from lignin: polyvinyl alcohol (PVA) blends as a cost effective and environmentally friendly precursor for supercapacitor application. Chapter 4 relates to the high surface area carbon nanofiber electrodes derived from PAN:Lignin polymer blends for high performance supercapacitors. Here, the incorporation of the advantageous properties of both PAN and Lignin as carbon sources and higher etch rate of lignin under CO2 as partial sacrificial polymer on performance of supercapacitors were investigated.