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Journal ArticleDOI

Alternately Dipping Method to Prepare Graphene Fiber Electrodes for Ultra-high-Capacitance Fiber Supercapacitors

21 Aug 2020-iScience (Elsevier)-Vol. 23, Iss: 8, pp 101396-101396
TL;DR: A facile alternately dipping (AD) method to coat graphene on wire-like substrates and shows an ultra-high specific capacitance, which is ∼1,000 times that of wet-spinning- and electro-deposition-fabricated neat graphene fibers and presents the highest specific capacitors to date.
About: This article is published in iScience.The article was published on 2020-08-21 and is currently open access. It has received 12 citations till now. The article focuses on the topics: Capacitance & Fiber.
Citations
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Journal ArticleDOI
19 Nov 2021-Energies
TL;DR: In this article, a review of various types of supercapacitors, such as electrochemical double-layer capacitors, hybrid supercapACs, and pseudo-supercapacitor, is presented.
Abstract: Supercapacitors (SCs) have received much interest due to their enhanced electrochemical performance, superior cycling life, excellent specific power, and fast charging–discharging rate. The energy density of SCs is comparable to batteries; however, their power density and cyclability are higher by several orders of magnitude relative to batteries, making them a flexible and compromising energy storage alternative, provided a proper design and efficient materials are used. This review emphasizes various types of SCs, such as electrochemical double-layer capacitors, hybrid supercapacitors, and pseudo-supercapacitors. Furthermore, various synthesis strategies, including sol-gel, electro-polymerization, hydrothermal, co-precipitation, chemical vapor deposition, direct coating, vacuum filtration, de-alloying, microwave auxiliary, in situ polymerization, electro-spinning, silar, carbonization, dipping, and drying methods, are discussed. Furthermore, various functionalizations of SC electrode materials are summarized. In addition to their potential applications, brief insights into the recent advances and associated problems are provided, along with conclusions. This review is a noteworthy addition because of its simplicity and conciseness with regard to SCs, which can be helpful for researchers who are not directly involved in electrochemical energy storage.

71 citations

Journal ArticleDOI
TL;DR: In this article, the characteristics of microwave-synthesized nanomaterials for next-generation energy storage devices are briefly demonstrated, and the past and present status of microwave chemistry for energy-related applications is discussed.
Abstract: Currently, nanomaterials are considered to be the backbone of modern civilization. Especially in the energy sector, nanomaterials (mainly, carbon- and metal oxide/hydroxide-based nanomaterials) have contributed significantly. Among the various green approaches for the synthesis of these nanomaterials, the microwave-assisted approach has attracted significant research interest worldwide. In this context, it is noteworthy to mention that because of their enhanced surface area, high conducting nature, and excellent electrical and electrochemical properties, carbon nanomaterials are being extensively utilized as efficient electrode materials for both supercapacitors and secondary batteries. In this review article, we briefly demonstrate the characteristics of microwave-synthesized nanomaterials for next-generation energy storage devices. Starting with the basics of microwave heating, herein, we illustrate the past and present status of microwave chemistry for energy-related applications, and finally present a brief outlook and concluding remarks. We hope that this review article will positively convey new insights for the microwave synthesis of nanomaterials for energy storage applications.

70 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarize the recent progress in the fabrication of GFs, and their state-of-the-art applications in energy storage/conversion devices, including supercapacitors, lithium-ion batteries, thermoelectric generators, solar cells and self-powered devices.

31 citations

Journal ArticleDOI
01 Feb 2022-Carbon
TL;DR: In this article , expanded molybdenum diselenides (MoSe2) was incorporated into graphene fibers via the assistance of ethylenediamine to achieve a 2.2-fold enhancement in volumetric capacitance.

21 citations

Journal ArticleDOI
01 Feb 2022-Carbon
TL;DR: In this article, expanded molybdenum diselenides (MoSe2) was incorporated into graphene fibers via the assistance of ethylenediamine to achieve a 2.2-fold enhancement in volumetric capacitance.

21 citations

References
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Journal ArticleDOI
TL;DR: Only the alternating pattern of single-double carbon bonds within the sp2 carbon ribbons provides a satisfactory explanation for the experimentally observed blue shift of the G band of the Raman spectra relative to graphite.
Abstract: We investigate Raman spectra of graphite oxide and functionalized graphene sheets with epoxy and hydroxyl groups and Stone−Wales and 5−8−5 defects by first-principles calculations to interpret our experimental results. Only the alternating pattern of single−double carbon bonds within the sp2 carbon ribbons provides a satisfactory explanation for the experimentally observed blue shift of the G band of the Raman spectra relative to graphite. To obtain these single−double bonds, it is necessary to have sp3 carbons on the edges of a zigzag carbon ribbon.

4,000 citations

Journal ArticleDOI
28 Jan 2016-Nature
TL;DR: This work bridges the technological gap between signal transduction, conditioning, processing and wireless transmission in wearable biosensors by merging plastic-based sensors that interface with the skin with silicon integrated circuits consolidated on a flexible circuit board for complex signal processing.
Abstract: Wearable sensor technologies are essential to the realization of personalized medicine through continuously monitoring an individual's state of health. Sampling human sweat, which is rich in physiological information, could enable non-invasive monitoring. Previously reported sweat-based and other non-invasive biosensors either can only monitor a single analyte at a time or lack on-site signal processing circuitry and sensor calibration mechanisms for accurate analysis of the physiological state. Given the complexity of sweat secretion, simultaneous and multiplexed screening of target biomarkers is critical and requires full system integration to ensure the accuracy of measurements. Here we present a mechanically flexible and fully integrated (that is, no external analysis is needed) sensor array for multiplexed in situ perspiration analysis, which simultaneously and selectively measures sweat metabolites (such as glucose and lactate) and electrolytes (such as sodium and potassium ions), as well as the skin temperature (to calibrate the response of the sensors). Our work bridges the technological gap between signal transduction, conditioning (amplification and filtering), processing and wireless transmission in wearable biosensors by merging plastic-based sensors that interface with the skin with silicon integrated circuits consolidated on a flexible circuit board for complex signal processing. This application could not have been realized using either of these technologies alone owing to their respective inherent limitations. The wearable system is used to measure the detailed sweat profile of human subjects engaged in prolonged indoor and outdoor physical activities, and to make a real-time assessment of the physiological state of the subjects. This platform enables a wide range of personalized diagnostic and physiological monitoring applications.

3,235 citations

Journal ArticleDOI
TL;DR: In this paper, the results obtained on the electrochemical behavior of electrochemical capacitors assembled in nonaqueous electrolyte are presented and the impedance of the supercapacitors is discussed in terms of complex capacitance and complex power.
Abstract: This paper presents the results obtained on the electrochemical behavior of electrochemical capacitors assembled in nonaqueous electrolyte. The first part is devoted to the electrochemical characterization of carbon-carbon 4 cm2 cells systems in terms of capacitance, resistance, and cyclability. The second part is focused on the electrochemical impedance spectroscopy study of the cells. Nyquist plots are presented and the impedance of the supercapacitors is discussed in terms of complex capacitance and complex power. This allows the determination of a relaxation time constant of the systems, and the real and the imaginary part of the complex power vs. the frequency plots give information on the supercapacitor cells frequency behavior. The complex impedance plots for both a supercapacitor and a tantalum dielectric capacitor cells are compared. © 2003 The Electrochemical Society. All rights reserved.

1,674 citations

Journal ArticleDOI
TL;DR: It is reported that GO is an amphiphile with hydrophilic edges and a more hydrophobic basal plane, and the ease of its conversion to chemically modified graphene could enable new opportunities in solution processing of functional materials.
Abstract: Graphite oxide sheet, now called graphene oxide (GO), is the product of chemical exfoliation of graphite and has been known for more than a century. GO has been largely viewed as hydrophilic, presumably due to its excellent colloidal stability in water. Here we report that GO is an amphiphile with hydrophilic edges and a more hydrophobic basal plane. GO can act like a surfactant, as measured by its ability to adsorb on interfaces and lower the surface or interfacial tension. Since the degree of ionization of the edge −COOH groups is affected by pH, GO’s amphiphilicity can be tuned by pH. In addition, size-dependent amphiphilicity of GO sheets is observed. Since each GO sheet is a single molecule as well as a colloidal particle, the molecule−colloid duality makes it behave like both a molecular and a colloidal surfactant. For example, GO is capable of creating highly stable Pickering emulsions of organic solvents like solid particles. It can also act as a molecular dispersing agent to process insoluble mat...

1,572 citations