299 research outputs found
Introduction to supercapacitors, materials and design
No full textSupercapacitors are power devices whose energy storage capability is lower than batteries. These supercapacitors are broadly divided into two types: electric double-layer capacitors and pseudocapacitors. Recently, battery-type electrodes are also used as supercapacitor electrodes to increase energy density. These various categories of supercapacitors are differentiated based on the selection of materials, electrolytes, and their design. Commercial supercapacitors offer various designs such as cylindrical and stacked layers for improving the energy storage capability of supercapacitors. This chapter serves as an introduction to this book, where a glimpse of materials and supercapacitor designs are compiled
Supercapacitors: Materials, Design, and Commercialization
No full textSupercapacitors: Materials, Design, and Commercialization provides a comprehensive overview of the latest research trends and opportunities in supercapacitors, particularly in terms of novel materials and electrolytes. The book addresses the transformation in supercapacitive technology from double layer capacitance to battery-type capacitance, providing a clear understanding of the conceptual differences between various charge storage processes for supercapacitors, charge storage based on materials and electrolytes, and calculation for capacitance for these charge processes. Detailed chapters discuss recent developments in materials, such as carbons, chalcogenides, MXene and phosphorene, various polymer nanocomposites, and polyoxometalates for supercapacitors. This is followed by in-depth coverage of electrolytes, including the evolution of electrolytes from aqueous to water-in-salt electrolytes and their role in improving the energy density of supercapacitors. The final part of the book examines the role of artificial intelligence in the design of supercapacitors, and latest developments in translating novel supercapacitor technologies from laboratory-scale research to a commercialization. © 2024 Elsevier Inc. All rights are reserved including those for text and data mining AI training and similar technologies
Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
No full textThis thesis aims to evaluate the suitability of magnesium cobalt oxide (MgCo2O4) as a pseudocapacitor electrode in asymmetric supercapacitors (ASCs) with improved energy density (ED) and power density (PD). MgCo2O4 belongs to ternary metal cobaltites having desirable electrochemical properties for energy storage devices such as batteries
and supercapacitors. In pseudocapacitors, charges are stored at the surface of an electrode by fast faradic reaction and offer improved ED and PD compared to conventional supercapacitors in which charge storage is limited by accumulation at the electrode–
electrolyte interface. In this research, three typical morphologies of MgCo2O4 are synthesized using molten salt method (MSM) and hydrothermal method (HT). These synthetic processes offer controllability of properties of the materials thereby produced and scalability of materials production. A high performing ternary metal cobaltite, viz. manganese cobalt oxide (MnCo2O4) is used as a control material owing to its higher theoretical capacitance (~3620 Fg-1) compared to that of MgCo2O4 (~3120 Fg-1) in all the above synthesis. In addition to the pure compounds, their graphene modified analogues are also synthesized. The materials are characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field
emission scanning electron microscopy (FESEM), and gas surface adsorption techniques. Electrochemical properties of MgCo2O4 and MnCo2O4 are evaluated using cyclic
voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) in a three-electrode system using 3 M LiOH as electrolyte. A detailed investigation of the pseudocapacitive performance of the various electrode including the
graphene modified ones on the specific capacitance (CS) has been undertaken in threeelectrode configuration. These characterizations revealed the superiority of MgCo2O4 over MnCo2O4 electrodes. Furthermore, performance of graphene modified MgCo2O4 and MnCo2O4 showed superior capacitance of ~570 and ~440 Fg-1, with capacitance
retention of 104 and 102%, respectively at the end of 3000 cycles. ASCs are fabricated using graphene modified MgCo2O4 (HS-G-MgCo2O4) and MnCo2O4 (HS-G-MnCo2O4)
as anodes and activated carbon (AC) as cathode. A trial and error method is adopted to determine suitable mass loading of the materials in respective electrodes for high ED and PD. Highest ED and PD are obtained for 1:1 wt.% mass loading in anode and cathode. The HS-G-MgCo2O4/AC delivered a maximum ED of ~31.05 Whkg-1 at PD of 1.8 kWkg-1, which is one of the best performances reported for ternary metal cobaltite based ASCs.
This research, therefore, identifies a promising pseudocapacitor electrode material for commercial deployment
Deep eutectic solvents as green and cost-effective supercapacitor electrolytes
No full textDeep eutectic solvents (DESs) have attracted widespread attention as a tempting and capable alternative to traditional electrolytes in energy storage system, particularly in terms of aqueous supercapacitors (SCs). Following the strategy of using eco-friendly and nonflammable electrolyte, low cost, and simple synthesis are other advantages for DESs. They also offer the possibility to construct aqueous all-climate SCs. This chapter comprehensively examines the recent developments and applications of eutectic solvents as electrolytes for SCs. It discusses the unique properties of DESs, their advantages, and challenges, and highlights their potential to enhance the performance and sustainability of SC devices. The chapter also sheds light on the ongoing research efforts and future directions in this rapidly evolving field
Soft, wireless electronics for the thermal characterization of skin and soft tissue
No full textExisting sensors to monitor physical biomarkers in living tissue are rigid, bulky and often require wired electronic connections for power and data transfer. Recent work has established a set of design principles that allow for the integration of traditionally rigid sensing electronics and wiring into form factors that are soft, flexible and stretchable. These sensors offer qualitative improvements in patient comfort and are comparable, if not superior to clinical gold standard technologies. The strong, conformal mechanical coupling between these sensors and underlying living tissue also opens new avenues for unusual sensing modalities with immediate applications in clinical medicine. Devices for the continuous thermal characterization of living tissue represent one such opportunity and the work presented here illustrates a set of materials, mechanics and electronics designs required to realize fully functional sensors for temperature and flow mapping through biological conduits. Advanced powering and data transmission and powering schemes relying on near-field communication and Bluetooth protocols allow the sensors to be continuously worn for extended periods. Measurements of hydration in outer skin layers, cerebrospinal fluid flow through indwelling ventricular shunts and blood flow through peripheral nerve vasculature represent three use cases in dermatology, neurosurgery and neuroscience, respectively. Systematic benchtop and theoretical studies illustrate the high levels of functionality of these devices, and IRB approved studies on over 30 patients and volunteers, along with comparisons to clinical gold standards highlight their potential beyond the laboratory.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-08-01The student, Siddharth Krishnan, accepted the attached license on 2019-06-01 at 19:10.The student, Siddharth Krishnan, submitted this Dissertation for approval on 2019-06-01 at 19:14.This Dissertation was approved for publication on 2019-06-11 at 10:22.DSpace SAF Submission Ingestion Package generated from Vireo submission #14013 on 2019-11-26 at 13:59:35Made available in DSpace on 2019-11-26T20:56:45Z (GMT). No. of bitstreams: 2
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Synthesis and Characterization of MnCo2O4 Cuboidal Microcrystals as a High Performance Psuedocapacitor Electrode
No full textManganese cobaltite (MnCo2O4) is currently under screening as a high performance supercapacitor electrode owing to its high theoretical capacitance, improved electrical conductivity and long term cyclic stability. Herein, we report synthesis of MnCo2O4 cuboidal microcrystals using hydrothermal method and compare its performance with its flakes prepared by solid combustion process. Crystal structure, surface properties, and electrochemical properties of the flakes are studied using X-ray diffraction, gas adsorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy. The electrochemical properties of MnCo2O4 flakes synthesized using hydrothermal synthesis are superior to that synthesized using the solid combustion process. Electrochemical properties of the cuboidal microcrystals (∼specific capacitance, CS ∼600 F g−1 @ 0.5 A g−1) are superior to those synthesized by the combustion process (CS ∼128 F g−1) due to improved faradic utilization of active surface area, layered cuboidal morphology, faster OH− ion penetration owing to higher diffusion coefficient, and larger voltage range available for electrochemical reaction
Associations of mammographic dense and nondense areas and body mass index with risk of breast cancer
No full textMammographic density measurements are associated with risk of breast cancer. Few studies have investigated the concurrent associations of mammographic dense and nondense areas, body mass index (weight (kg)/height (m)2), and ages at mammogram and diagnosis with breast cancer risk. We conducted a matched, case-control study nested within the Melbourne Collaborative Cohort Study (cohort recruitment in 1990-1994 and follow-up until 2007) to estimate the associations between these factors and breast cancer risk under alternative causal models. Mammographic dense area was positively associated with risk, and the strength of this association was only slightly influenced by the choice of the causal model (relative risk per 1 standard deviation = 1.50, 95% confidence interval: 1.32, 1.70). Mammographic nondense area was inversely associated with risk under the assumption that fat in the body and fat in the breast cause breast cancer through independent mechanisms (relative risk per 1 standard deviation = 0.75, 95% confidence interval: 0.65, 0.86), whereas it was not associated with risk under the assumption that they are both proxies of adiposity. Knowledge about the biological mechanisms regulating the role played by mammographic nondense area and body fat on breast cancer risk is essential to better estimate their impacts on individual risk. © The Author 2013
Drawing the Line: How African, Caribbean and White British Women Live Out Psychologically Abusive Experiences
No full textThe final, definitive version of this paper has been published in Violence Against Women, 19 (9):1104-32, Sept 2013 by SAGE Publications Ltd, All rights reserved. © The Author(s) 2013.
The online version of this article can be found at: http://vaw.sagepub.com/content/19/9/110
Kenaf-based activated carbon: A sustainable solution for high-performance aqueous symmetric supercapacitors
No full textThis study presents an innovative method for synthesizing activated carbon with an exceptionally high surface area (3359 m2 g-1) using kenaf fiber-based biochar through chemical activation. The achieved specific surface area surpasses activated carbon derived from other reported fiber-based precursors. The resulting activated carbon was investigated as electrodes for supercapacitors, revealing a remarkable maximum capacitance of 312 F g-1 at a current density of 0.5 A g-1. An aqueous symmetric supercapacitor employing these high-surface-area electrodes exhibited an outstanding energy density of 18.9 Wh kg-1 at a power density of 250 W kg-1. Notably, the supercapacitor retained exceptional capacitance, maintaining 93% of its initial capacitance even after 5000 charge-discharge cycles
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