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A new method of supercapacitor online health diagnosis based on an electric model and on experimental results obtained by calendar ageing tests is proposed.The calendar ageing of supercapacitor is mainly related to thermal and vol...
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A new method of supercapacitor online health diagnosis based on an electric model and on experimental results obtained by calendar ageing tests is proposed.The calendar ageing of supercapacitor is mainly related to thermal and voltage constraints from the application. This ageing causes the degradation of supercapacitor performances which can finally lead to failures. In vehicle applications, the goal is to avoid these failures which may have serious consequences and high non-quality costs. The device survey and ageing state detection are a priority for anticipating the problems. This paper presents the case of calendar ageing tests on supercapacitors made of activated carbon and organic electrolyte. The ageing is performed at constant temperature (65℃) under a 2.9 Vdc bias voltage. These tests permit to highlight online and in real-time the measurable external indicators of ageing.
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The inception of flexible supercapacitors that can work steadily under large deformation has been a research hotspot in recent years. To improve the device's stability, one needs to find innovative solutions to inevitable delamina...
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The inception of flexible supercapacitors that can work steadily under large deformation has been a research hotspot in recent years. To improve the device's stability, one needs to find innovative solutions to inevitable delaminations of electroactive components, which are resulted by relative displacement under external force. Herein, an extensive all-in-one hydrogel-based supercapacitor is designed. Based on the special physical properties of hydrogels, the polypyrrole-polyvinyl alcohol/dilute sulphuric acid-polypyrrole (PHP) sandwiched device shows the harmonious mechanical and electrical properties. When the tensile strain of PHP reaches to 110%, the areal capacitance still maintains at 90%. Similarly, the high areal capacitance retention under compression and twisting also verifies that the PPy active layer tightly permeates and adheres to the PVA-H2SO4 electrolyte layer. In addition to the fascinating mechanical properties, the undetectable contact angle reveals a superhydrophilic surface which is beneficial to provide an easy access for electrolyte ions, thus enhancing the electrochemical performance. Moreover, a stable cycle performance (97% after 10000 cycles) is obtained due to the excellent water retention ability which prevents the loss of electrolyte. The maximum extended voltage window is 1 V with the power density of 500 mu W cm(-2) (the energy density of 6.94 mu W h cm(-2)). These hydrogel-based supercapacitors can be immune to the harm caused by external forces and maintain good mechanical integrity and electrochemical stability. Developing the hydrogel-based supercapacitors can provide a fresh perspective on multifunction applications and herald a new territory for flexible energy storage devices. (C) 2019 Elsevier B.V. All rights reserved.
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Human creed is in the constant quest for energy and its storage possibilities. The fast depletion of non-renewable sources of energy and the lower power conversion efficiency of renewable sources along with the decentralized energ...
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Human creed is in the constant quest for energy and its storage possibilities. The fast depletion of non-renewable sources of energy and the lower power conversion efficiency of renewable sources along with the decentralized energy generation, forces the focus to highly efficient energy storage devices. In this regard, technology, industry and the supply chain of batteries and capacitors are matured and is full-fledged. A further improvement is possible with the faster charging-discharging cycles, long life time, and environmental friendly alternatives. Hence Supercapacitors (SCs) take the lead in the energy storage research arena. Depending on the mechanism exploited for storing charges, SCs are classified as pseudocapacitors, electric double layer capacitance based SCs and hybrid SCs. Each of these SCs have their own distinct advantages over the other. In this review, we compare the mechanisms related to each of these SCs. There are various factors that determine the feasibility of a SC for commercialization. This include a high specific capacitance at a given current density, high energy density, long life time, a wide potential window for operation (2 -4 V) and high active mass loading (>10 mg/cm(2)). A SC which can satisfy these conditions can be directly translated to mass production. In this regard, the obtained device should also be mass producible and green. This greatly depends on the type of materials used for electrodes and electrolytes. There are a wide range of materials which are being explored as SC electrodes. This include transition metal oxides, carbides, nitrides, phosphides, carbon based materials, conducting polymers and composites involving two or more of these materials. In addition to that, the microstructure of these materials are also of prime importance in deciding the electrochemical performance. Hence various strategies like different synthesis process ranging from soft chemistry, freeze drying to laser ablation, use of 3D printing, building hierarchal porous architecture, use of templates and foams are explored. Various microstructures like sheets, ribbons, flakes, intertwined structures, aerogels and many more are experimented. In this review, we focus on the various materials used as electrolytes and electrodes and their synthesis/fabrication procedure. A detailed comparison based on the materials used and the performance obtained are compared for the three basic type of SCs. The role of active mass loading and its importance are briefly discussed. Finally the current direction of supercapacitor research, commercial applications of supercapacitors and prospective future directions have been discussed. The objective of this review is to provide a bird's eye view on the various aspects of SC starting from their synthesis, processing, performance evaluation and industrial application.
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Limited by 2D geometric morphology and low bulk packing density, developing graphene-based flexible/compressible supercapacitors with high specific capacitances (gravimetric/volumetric/areal), especially at high rates, is an outst...
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Limited by 2D geometric morphology and low bulk packing density, developing graphene-based flexible/compressible supercapacitors with high specific capacitances (gravimetric/volumetric/areal), especially at high rates, is an outstanding challenge. Here, a strategy for the synthesis of free-standing graphene ribbon films (GRFs) for high-performance flexible and compressible supercapacitors through blade-coating of interconnected graphene oxide ribbons and a subsequent thermal treatment process is reported. With an ultrahigh mass loading of 21 mg cm(-2), large ion-accessible surface area, efficient electron and ion transport pathways as well as high packing density, the compressed multilayer-folded GRF films (F-GRF) exhibit ultrahigh areal capacitance of 6.7 F cm(-2) at 5 mA cm(-2), high gravimetric/volumetric capacitances (318 F g(-1), 293 F cm(-3)), and high rate performance (3.9 F cm(-2) at 105 mA cm(-2)), as well as excellent cycling stability (109% of capacitance retention after 40 000 cycles). Furthermore, the assembled F-GRF symmetric supercapacitor with compressible and flexible characteristics, can deliver an ultrahigh areal energy density of 0.52 mWh cm(-2) in aqueous electrolyte, almost two times higher than the values obtained from symmetric supercapacitors with comparable dimensions.
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A simple electrical model has been established to describe supercapacitor behaviour as a function of frequency, voltage and temperature for hybrid vehicle applications. The electrical model consists of 14 RLC elements, which have ...
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A simple electrical model has been established to describe supercapacitor behaviour as a function of frequency, voltage and temperature for hybrid vehicle applications. The electrical model consists of 14 RLC elements, which have been determined from experimental data using electrochemical impedance spectroscopy (EIS) applied on a commercial supercapacitor. The frequency analysis has been extended for the first time to the millihertz range to take into account the leakage current and the charge redistribution on the electrode. Simulation and experimental results of supercapacitor charge and discharge have been compared and analysed. A good correlation between the model and the EIS results has been demonstrated from 1 mHz to 1 kHz, from -20 to 60℃ and from 0 to 2.5 V.
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The present paper compares the performance of an n/p-type polymer supercapactior based on n-and p-doped poly(3-methylthiophene) (pMeT) and of a hybrid supercapacitor, based on p-doped pMeT as positive electrode and activated carbo...
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The present paper compares the performance of an n/p-type polymer supercapactior based on n-and p-doped poly(3-methylthiophene) (pMeT) and of a hybrid supercapacitor, based on p-doped pMeT as positive electrode and activated carbon as negative, with that of a double-layer activated carbon supercapacitor (DLCSs), which is representative of the ucrrent state of supercapacitor technology. The data on the n/p-type supercapacitor demonstrate that this device is not fully competitive with the DLCSs because of its lower discharge capacity, although all the charge is delivered at high potentials and this makes it suitable for high-voltage applications. The data on the hybrid supercapacitor demonstrate that this device outperforms DLCSs, delivering higher average and maximum specific powers and significantly higher specific energy in the potential region above 1.0 V.
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Nanomaterials with quasi-zero, one and two dimensionalities, including silicon nanoparticles, carbon nanotubes, titanium oxide particles and graphene flakes, have been incorporated into the conducting polymer polyaniline to form n...
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Nanomaterials with quasi-zero, one and two dimensionalities, including silicon nanoparticles, carbon nanotubes, titanium oxide particles and graphene flakes, have been incorporated into the conducting polymer polyaniline to form nanocomposite materials for making flexible supercapacitor sheets. Characterization of the capacitor sheets showed that the inclusion of the nanomaterials in polyaniline has significantly improved the energy and power capabilities of the capacitor. In particular, a specific capacitance of 477.1. F/g has been obtained. The important properties of carbon nanotubes of improving the charge storage and reducing the resistance of the nanocomposite material and hence to enhance the power capability of the capacitor sheets have been studied. Stacks of capacitor sheets have been used to power a LED lamp to demonstrate the potential of the nanocomposite-based capacitor sheet in illumination applications.
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Thin-film supercapacitors are promising candidates for energy storage in wearable electronics due to their mechanical flexibility, high power density, long cycling life, and fast-charging capability. In addition to all of these fe...
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Thin-film supercapacitors are promising candidates for energy storage in wearable electronics due to their mechanical flexibility, high power density, long cycling life, and fast-charging capability. In addition to all of these features, device transparency would open up completely new opportunities in wearable devices, virtual reality or in heads-up displays for vehicle navigation. Here a method is introduced for micromolding Ag/porous carbon and Ag/NixFeyOz@reduced graphene oxide (rGO) into grid-like patterns on polyethylene terephthalate foils to produce transparent thin-film supercapacitors and hybrid supercapacitors. The supercapacitor delivers a high areal capacitance of 226.8 mu F cm(-2)at a current density of 3 mu A cm(-2)and with a transparency of 70.6%. The cycling stability is preserved even after 1000 cycles under intense bending. A hybrid supercapacitor is additionally fabricated by integrating two electrodes of Ag/porous carbon and Ag/NixFeyOz@rGO. It offers an areal capacitance of 282.1 mu F cm(-2)at a current density of 3 mu A cm(-2), a transparency of 73.3% and the areal capacitance only decreases slightly under bending. This work indicates that micromolding of nano- and micro-sized powders represents a powerful method for preparing regular electrode patterns, which are fundamental for the development of transparent energy storage devices.
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