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Showing papers on "Supercapacitor published in 2010"


Journal ArticleDOI
TL;DR: The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face.
Abstract: A supercapacitor with graphene-based electrodes was found to exhibit a specific energy density of 85.6 Wh/kg at room temperature and 136 Wh/kg at 80 °C (all based on the total electrode weight), measured at a current density of 1 A/g. These energy density values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face. The curved morphology enables the formation of mesopores accessible to and wettable by environmentally benign ionic liquids capable of operating at a voltage >4 V.

2,852 citations


Journal ArticleDOI
TL;DR: This work demonstrates microsupercapacitors with powers per volume that are comparable to electrolytic capacitors, capacitances that are four orders of magnitude higher, and energies per volume higher than conventional supercapacitor.
Abstract: Electrochemical capacitors, also called supercapacitors, store energy in two closely spaced layers with opposing charges, and are used to power hybrid electric vehicles, portable electronic equipment and other devices¹. By offering fast charging and discharging rates, and the ability to sustain millions of ²⁻⁵, electrochemical capacitors bridge the gap between batteries, which offer high energy densities but are slow, and conventional electrolytic capacitors, which are fast but have low energy densities. Here, we demonstrate microsupercapacitors with powers per volume that are comparable to electrolytic capacitors, capacitances that are four orders of magnitude higher, and energies per volume that are an order of magnitude higher. We also measured discharge rates of up to 200 V s⁻¹, which is three orders of magnitude higher than conventional supercapacitors. The microsupercapacitors are produced by the electrophoretic deposition of a several micrometre-thick layer of nanostructured carbon onions⁶‚⁷ with diameters of 6-7 nm. Integration of these nanoparticles in a microdevice with a high surface-to-volume ratio, without the use of organic binders and polymer separators, improves performance because of the ease with which ions can access the active material. Increasing the energy density and discharge rates of supercapacitors will enable them to compete with batteries and conventional electrolytic capacitors in a number of applications.

2,469 citations


Journal ArticleDOI
Qiong Wu1, Yuxi Xu1, Zhiyi Yao1, Anran Liu1, Gaoquan Shi1 
31 Mar 2010-ACS Nano
TL;DR: Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance at a discharge rate of 0.3 A g(-1) and exhibited greatly improved electrochemical stability and rate performances.
Abstract: Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 × 102 S m−1) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g−1) at a discharge rate of 0.3 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

2,089 citations


Journal ArticleDOI
TL;DR: Ni(OH)2 nanocrystals grown on graphene sheets with various degrees of oxidation are investigated as electrochemical pseudocapacitor materials for potential energy storage applications in this paper, where they exhibit a high specific capacitance of ∼1335 F/g at a charge and discharge current density of 2.8 A/g and ∼953 F/m at 45.7 A/m with excellent cycling ability.
Abstract: Ni(OH)2 nanocrystals grown on graphene sheets with various degrees of oxidation are investigated as electrochemical pseudocapacitor materials for potential energy storage applications. Single-crystalline Ni(OH)2 hexagonal nanoplates directly grown on lightly oxidized, electrically conducting graphene sheets (GS) exhibit a high specific capacitance of ∼1335 F/g at a charge and discharge current density of 2.8 A/g and ∼953 F/g at 45.7 A/g with excellent cycling ability. The high specific capacitance and remarkable rate capability are promising for applications in supercapacitors with both high energy and power densities. A simple physical mixture of pre-synthesized Ni(OH)2 nanoplates and graphene sheets shows lower specific capacitance, highlighting the importance of direct growth of nanomaterials on graphene to impart intimate interactions and efficient charge transport between the active nanomaterials and the conducting graphene network. Single-crystalline Ni(OH)2 nanoplates directly grown on graphene she...

1,751 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present state-of-the-art energy storage topologies for hybrid electric vehicles and plug-in hybrid vehicles (PHEVs) and compare battery, UC, and fuel cell technologies.
Abstract: The fuel economy and all-electric range (AER) of hybrid electric vehicles (HEVs) are highly dependent on the onboard energy-storage system (ESS) of the vehicle. Energy-storage devices charge during low power demands and discharge during high power demands, acting as catalysts to provide energy boost. Batteries are the primary energy-storage devices in ground vehicles. Increasing the AER of vehicles by 15% almost doubles the incremental cost of the ESS. This is due to the fact that the ESS of HEVs requires higher peak power while preserving high energy density. Ultracapacitors (UCs) are the options with higher power densities in comparison with batteries. A hybrid ESS composed of batteries, UCs, and/or fuel cells (FCs) could be a more appropriate option for advanced hybrid vehicular ESSs. This paper presents state-of-the-art energy-storage topologies for HEVs and plug-in HEVs (PHEVs). Battery, UC, and FC technologies are discussed and compared in this paper. In addition, various hybrid ESSs that combine two or more storage devices are addressed.

1,490 citations


Journal ArticleDOI
21 Sep 2010-ACS Nano
TL;DR: A high-voltage asymmetric electrochemical capacitor based on graphene as negative electrode and a MnO(2) nanowire/graphene composite (MGC) as positive electrode in a neutral aqueous Na( 2)SO(4) solution as electrolyte opens up the possibility of graphene-based composites for applications in safe aqueously electrolyte-based high- voltage asymmetric ECs with high energy and power densities.
Abstract: In order to achieve high energy and power densities, we developed a high-voltage asymmetric electrochemical capacitor (EC) based on graphene as negative electrode and a MnO2 nanowire/graphene composite (MGC) as positive electrode in a neutral aqueous Na2SO4 solution as electrolyte. MGC was prepared by solution-phase assembly of graphene sheets and α-MnO2 nanowires. Such aqueous electrolyte-based asymmetric ECs can be cycled reversibly in the high-voltage region of 0−2.0 V and exhibit a superior energy density of 30.4 Wh kg−1, which is much higher than those of symmetric ECs based on graphene//graphene (2.8 Wh kg−1) and MGC//MGC (5.2 Wh kg−1). Moreover, they present a high power density (5000 W kg−1 at 7.0 Wh kg−1) and acceptable cycling performance of ∼79% retention after 1000 cycles. These findings open up the possibility of graphene-based composites for applications in safe aqueous electrolyte-based high-voltage asymmetric ECs with high energy and power densities.

1,416 citations


Journal ArticleDOI
TL;DR: Graphene is an emerging carbon material that may soon find practical applications as discussed by the authors, and it is a potential electrode material for electrochemical energy storage, with desirable properties to meet the specific requirements for the design and configuration of advanced supercapacitor devices.
Abstract: Graphene is an emerging carbon material that may soon find practical applications. With its unusual properties, graphene is a potential electrode material for electrochemical energy storage. This article highlights recent research progress in graphene-based materials as supercapacitor electrodes. With a brief description of the working principle of supercapacitors, research progress towards the synthesis and modification of graphene-based materials, including graphene oxide, fullerenes, and carbon nanotubes, is presented. Applications of such materials with desirable properties to meet the specific requirements for the design and configuration of advanced supercapacitor devices are summarized and discussed. Future research trends towards new approaches to the design and synthesis of graphene-based nanostructures and architectures for electrochemical energy storage are proposed.

1,333 citations


Journal ArticleDOI
01 Nov 2010-Carbon
TL;DR: In this paper, a self-limiting deposition of nanoscale MnO2 on the surface of graphene under microwave irradiation was proposed to synthesize graphene-MnO2 composites.

1,263 citations


Journal ArticleDOI
TL;DR: In this paper, the carbon materials used for electrochemical capacitors were reviewed and discussed the contribution of the surfaces owing to micropores and other larger pores to the capacitance and rate performance of the electric double-layer capacitors.

1,249 citations


Journal ArticleDOI
24 Sep 2010-Science
TL;DR: Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces, and capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.
Abstract: Electric double-layer capacitors (DLCs) can have high storage capacity, but their porous electrodes cause them to perform like resistors in filter circuits that remove ripple from rectified direct current. We have demonstrated efficient filtering of 120-hertz current with DLCs with electrodes made from vertically oriented graphene nanosheets grown directly on metal current collectors. This design minimized electronic and ionic resistances and produced capacitors with RC time constants of less than 200 microseconds, in contrast with ~1 second for typical DLCs. Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces. Capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.

1,233 citations


Journal ArticleDOI
Chuizhou Meng1, Changhong Liu1, Luzhuo Chen1, Chunhua Hu1, Shou-Shan Fan1 
TL;DR: This work demonstrates a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte.
Abstract: In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 μA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

Journal ArticleDOI
TL;DR: In this paper, aqueous dispersions of polymer-modified graphene sheets were prepared via in situ reduction of exfoliated graphite oxides in the presence of cationic poly(ethyleneimine) (PEI).
Abstract: Stable aqueous dispersions of polymer-modified graphene sheets were prepared via in situ reduction of exfoliated graphite oxides in the presence of cationic poly(ethyleneimine) (PEI). The resultant water-soluble PEI-modified graphene sheets were then used for sequential self-assembly with acid-oxidized multiwalled carbon nanotubes, forming hybrid carbon films. These hybrid films were demonstrated to possess an interconnected network of carbon structures with well-defined nanopores to be promising for supercapacitor electrodes, exhibiting a nearly rectangular cyclic voltammogram even at an exceedingly high scan rate of 1 V/s with an average specific capacitance of 120 F/g.

Journal ArticleDOI
TL;DR: It is argued that a large, collaborative international research programme is necessary to fully develop the potential of electrochemical capacitors.
Abstract: Electrochemical capacitors, also known as supercapacitors, are becoming increasingly important components in energy storage, although their widespread use has not been attained due to a high cost/performance ratio. Fundamental research is contributing to lowered costs through the engineering of new materials. Currently the most viable materials used in electrochemical capacitors are biomass-derived and polymer-derived activated carbons, although other carbon materials are useful research tools. Metal oxides could result in a step change for electrochemical capacitor technology and is an exciting area of research. The selection of an appropriate electrolyte and electrode structure is fundamental in determining device performance. Although there are still many uncertainties in understanding the underlying mechanisms involved in electrochemical capacitors, genuine progress continues to be made. It is argued that a large, collaborative international research programme is necessary to fully develop the potential of electrochemical capacitors.

Journal ArticleDOI
TL;DR: In this article, layer-by-layer techniques are used to assemble an electrode that consists of additive-free, densely packed and functionalized multi-walled carbon nanotubes, which can store lithium up to a reversible gravimetric capacity of approximately 200 mA h g(-1) while also delivering 100 kW kg(electrode) of power and providing lifetimes in excess of thousands of cycles.
Abstract: Energy storage devices that can deliver high powers have many applications, including hybrid vehicles and renewable energy. Much research has focused on increasing the power output of lithium batteries by reducing lithium-ion diffusion distances, but outputs remain far below those of electrochemical capacitors and below the levels required for many applications. Here, we report an alternative approach based on the redox reactions of functional groups on the surfaces of carbon nanotubes. Layer-by-layer techniques are used to assemble an electrode that consists of additive-free, densely packed and functionalized multiwalled carbon nanotubes. The electrode, which is several micrometres thick, can store lithium up to a reversible gravimetric capacity of approximately 200 mA h g(-1)(electrode) while also delivering 100 kW kg(electrode)(-1) of power and providing lifetimes in excess of thousands of cycles, both of which are comparable to electrochemical capacitor electrodes. A device using the nanotube electrode as the positive electrode and lithium titanium oxide as a negative electrode had a gravimetric energy approximately 5 times higher than conventional electrochemical capacitors and power delivery approximately 10 times higher than conventional lithium-ion batteries.

Journal ArticleDOI
TL;DR: The results demonstrated that MnO(2) is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode, and such ternary composite is very promising for the next generation high performance electrochemical supercapacitors.
Abstract: For efficient use of metal oxides, such as MnO2 and RuO2, in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO2), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO2/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO2 (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO2 is effectively utilized with assistance of ot...

Journal ArticleDOI
TL;DR: The electrochemically reduced graphene oxide (ER-G) has shown promising features for applications in energy storage, biosensors, and electrocatalysis as discussed by the authors, which can be used for energy storage.
Abstract: Graphene oxide is electrochemically reduced which is called electrochemically reduced graphene oxide (ER-G). ER-G is characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The oxygen content is significantly decreased and the sp2 carbon is restored after electrochemical reduction. ER-G exhibits much higher electrochemical capacitance and cycling durability than carbon nanotubes (CNTs) and chemically reduced graphene; the specific capacitance measured with cyclic voltammetry (20 mV s−1) is ∼165, ∼86, and ∼100 F g−1 for ER-G, CNTs, and chemically reduced graphene, respectively. The electrochemical reduction of oxygen and hydrogen peroxide are greatly enhanced on ER-G electrodes as compared with CNTs. ER-G has shown promising features for applications in energy storage, biosensors, and electrocatalysis.

Journal ArticleDOI
26 Jul 2010-ACS Nano
TL;DR: This work has successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology.
Abstract: In the work described in this paper, we have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes. These hybrid nanostructured films, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology, were produced by using a filtration method. Here, manganese dioxide nanowire/SWNT hybrid films worked as the positive electrode, and indium oxide nanowire/SWNT hybrid films served as the negative electrode in a designed ASC. In our design, charges can be stored not only via electrochemical double-layer capacitance from SWNT films but also through a reversible faradic process from transition-metal-oxide nanowires. In addition, to obtain stable electrochemical behavior during charging/discharging cycles in a 2 V potential window, the mass balance between two electrodes has been optimized. Our optimized hybrid nanostructured ASCs exhibited a superior devi...

Journal ArticleDOI
TL;DR: The effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance are discussed and ways for the improvement in the performance ofsupercapacitor are found.
Abstract: As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

Journal ArticleDOI
TL;DR: In this article, a novel nano-architecture is developed by combining the nanostructured conductive polymer polypyrrole with highly electrically conductive graphene nanosheets in a multilayered configuration to achieve high specific capacitance and low electronic resistance for supercapacitor electrode applications.
Abstract: A novel nanoarchitecture is developed by combining the nanostructured conductive polymer polypyrrole with highly electrically conductive graphene nanosheets in a multilayered configuration to achieve high specific capacitance and low electronic resistance for supercapacitor electrode applications. The fibrous network of polypyrrole nanowires with high electrolyte ionic accessibility was interspersed with electrically conductive monolayers of highly aligned large sized graphene nanosheets as a series of current collectors within the macroscopic configuration for enhanced electronic charge transport inside the electrode. A fabrication method relying on capillary force driven self-assembly coupled with the strong van der Waals attraction between highly aromatic graphene basal plane and π conjugated conductive polymer chains was employed to create a 100% binder free multilayered composite structure of these two distinct nanoscale elements to construct the electrode. This multilayer composite electrode exhibit...

Journal ArticleDOI
TL;DR: To emerge as an important energy storage technology in the future, advanced supercapacitors must be developed with higher operating voltage and higher energy and power delivery, while maintaining high cyclability.
Abstract: Supercapacitors are electrochemical energy storage systems that store energy directly and physically as charge, whereas batteries, for example Li-ion cells, store energy in chemical reactants capable of generating charge. [ 1 ] Accordingly, the energy density of supercapacitors ( < 10 Wh kg − 1 ) is lower than batteries ( > 100 Wh kg − 1 ). However, their power is signifi cantly higher and their lifetime longer. As such, supercapacitors are expected to play a crucial role where superior power performance is required. The importance of supercapacitors is highlighted by a report from the US Department of Energy assigning equal importance to batteries and supercapacitors. [ 2 ] Examples of envisioned largescale applications of supercapacitors are load-leveling in solar, wind, and other energy sources and energy recovery from regenerative braking in automobiles. [ 2 , 3 ] To emerge as an important energy storage technology in the future, advanced supercapacitors must be developed with higher operating voltage and higher energy and power delivery, while maintaining high cyclability. Hitherto, activated carbon (AC) has been the electrode material of choice due to its high surface area (1000–2000 m 2

Journal ArticleDOI
TL;DR: A flexible graphene/polyaniline hybrid material as a supercapacitor electrode was synthesized by an in situ polymerization-reduction/dedoping-redoping process and showed better electrochemical performances than the pure individual components.
Abstract: A flexible graphene/polyaniline hybrid material as a supercapacitor electrode was synthesized by an in situ polymerization-reduction/dedoping-redoping process. This product was first prepared in an ethylene glycol medium, then treated with hot sodium hydroxide solution to obtain the reduced graphene oxide/polyaniline hybrid material. Sodium hydroxide also acted as a dedoping reagent for polyaniline in the composite. After redoping in an acidic solution, the thin, uniform and flexible conducting graphene/polyaniline product was obtained with unchanged morphology. The chemical structure of the materials was characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. The composite material showed better electrochemical performances than the pure individual components. A high specific capacitance of 1126 F g−1 was obtained with a retention life of 84% after 1000 cycles for supercapacitors. The energy density and power density were also better than those of pure component materials.

Journal ArticleDOI
TL;DR: The enhanced specific capacitance and cycling life implies a synergistic effect between two components, of significance for developing new doped PANI materials for supercapacitors.
Abstract: Graphene oxide, a single layer of graphite oxide (GO), has been used to prepare graphene oxide/polyaniline (PANI) composite with improved electrochemical performance as supercapacitor electrode by in situ polymerization using a mild oxidant. The composites are synthesized under different mass ratios, using graphite as start material with two sizes: 12 500 and 500 mesh. The result shows that the morphology of the prepared composites is influenced dramatically by the different mass ratios. The composites are proposed to be combined through electrostatic interaction (doping process), hydrogen bonding, and π−π stacking interaction. The highest initial specific capacitances of 746 F g−1 (12 500 mesh) and 627 F g−1 (500 mesh) corresponding to the mass ratios 1:200 and 1:50 (graphene oxide/aniline) are obtained, compared to PANI of 216 F g−1 at 200 mA g−1 by charge−discharge analysis between 0.0 and 0.4 V. The improved capacitance retention of 73% (12 500 mesh) and 64% (500 mesh) after 500 cycles is obtained for...

Journal ArticleDOI
01 May 2010-Carbon
TL;DR: Graphene nanosheet/carbon black composites were prepared by the ultrasonication and in situ reduction methods as mentioned in this paper, and the resulting composite is a promising carbon material for supercapacitors.

Journal ArticleDOI
01 Jul 2010-ACS Nano
TL;DR: High-performance capacitive behavior indicates that the SnO2/MnO2 composite is a very promising electrode material for fabricating supercapacitors.
Abstract: In this paper, a very simple solution-based method is employed to coat amorphous MnO2 onto crystalline SnO2 nanowires grown on stainless steel substrate, which utilizes the better electronic conductivity of SnO2 nanowires as the supporting backbone to deposit MnO2 for supercapacitor electrodes. Cyclic voltammetry (CV) and galvanostatic charge/discharge methods have been carried out to study the capacitive properties of the SnO2/MnO2 composites. A specific capacitance (based on MnO2) as high as 637 F g−1 is obtained at a scan rate of 2 mV s−1 (800 F g−1 at a current density of 1 A g−1) in 1 M Na2SO4 aqueous solution. The energy density and power density measured at 50 A g−1 are 35.4 W h kg−1 and 25 kW kg−1, respectively, demonstrating the good rate capability. In addition, the SnO2/MnO2 composite electrode shows excellent long-term cyclic stability (less than 1.2% decrease of the specific capacitance is observed after 2000 CV cycles). The temperature-dependent capacitive behavior is also discussed. Such hi...

Journal ArticleDOI
01 Dec 2010-Carbon
TL;DR: In this paper, high oxygen content (10−15% at.%) nanotextured carbons were obtained by pyrolysis of seaweeds at 600−750°C and applied as electrodes for supercapacitors in H2SO4, KOH and Na2SO 4 aqueous media.

Journal ArticleDOI
TL;DR: In this paper, the homogeneous distribution of Co 3 O 4 nanoparticles (3-5-nm in size) on graphene sheets has been observed and the composite exhibits excellent long cycle life along with ∼95.6% specific capacitance retained after 2000 cycle tests.

Journal ArticleDOI
TL;DR: In this paper, a review of the development of high voltage spinel LiNi 0.5 Mn 1.5 O 4 cathode material is presented, including its synthesis, structural characterization, effect of doping, and effect of coating.

Journal ArticleDOI
TL;DR: In this paper, two-electrode sandwich type supercapacitor cells containing 1 M H2SO4 were used to construct sugar cane bagasse carbons with ZnCl2 activation.

Journal ArticleDOI
24 Feb 2010-ACS Nano
TL;DR: It is demonstrated, for the first time, how the preparation and application of templated carbide-derived carbon (CDC) can overcome the present limitations and show the route for dramatic performance enhancement.
Abstract: Microporous carbons, produced by selective etching of metal carbides in a chlorine-containing environment, offer narrow distribution of micropores and one of the highest specific capacitances reported when used in electrical double layer capacitors (EDLC) with organic electrolytes. Previously, the small micropores in these carbons served as an impediment to ion transport and limited the power storage characteristics of EDLC. Here we demonstrate, for the first time, how the preparation and application of templated carbide-derived carbon (CDC) can overcome the present limitations and show the route for dramatic performance enhancement. The ordered mesoporous channels in the produced CDC serve as ion-highways and allow for very fast ionic transport into the bulk of the CDC particles. The enhanced transport led to 85% capacitance retention at current densities up to ∼20 A/g. The ordered mesopores in silicon carbide precursor also allow the produced CDC to exhibit a specific surface area up to 2430 m2/g and a ...

Journal ArticleDOI
TL;DR: In this article, carbon-based micro-supercapacitors dedicated to energy storage in self-powered modules were fabricated with inkjet printing technology on silicon substrate, where an ink was first prepared by mixing an activated carbon powder with a PTFE polymer binder in ethylene glycol stabilized with a surfactant.