Capacitors, Supercapacitors, Energy storage devices Research Papers (original) (raw)

Renewable energy sources (RESs) such as wind and solar are frequently hit by fluctuations due to, for example, insufficient wind or sunshine. Energy storage technologies (ESTs) mitigate the problem by storing excess energy generated and... more

Renewable energy sources (RESs) such as wind and solar are frequently hit by fluctuations due to, for example, insufficient wind or sunshine. Energy storage technologies (ESTs) mitigate the problem by storing excess energy generated and then making it accessible on demand. While there are various EST studies, the literature remains isolated and dated. The comparison of the characteristics of ESTs and their potential applications is also short. This paper fills this gap. Using selected criteria, it identifies key ESTs and provides an updated review of the literature on ESTs and their application potential to the renewable energy sector. The critical review shows a high potential application for Li-ion batteries and most fit to mitigate the fluctuation of RESs in utility grid integration sector. However, for Li-ion batteries to be fully adopted in the RESs utility grid integration, their cost needs to be reduced.

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... more

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 biomassderived 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.

Energy and power capability of supercapacitors are important because of their use in providing backup power or pulse current to electronic/electric products or systems. The choice of the electrode materials, such as... more

Energy and power capability of supercapacitors are important because of their use in
providing backup power or pulse current to electronic/electric products or systems. The choice of
the electrode materials, such as carbons, metal oxides or conducting polymers determines their
mechanism of energy storage process. This short review focuses on the supercapacitors using
porous carbon electrodes prepared from fibers of oil palm empty fruit bunches. The specific energy
and specific power of these supercapacitors were analyzed to observe the change in their trend with
respect to the electrode preparation parameters affectingthe porosity, structure, surface chemistry
and electrical conductivity of electrodes, and hence influence the energy and power capability of
supercapacitors. This review finds that the trend of changein specific energy and specific power is
not in favor of the expectation that both the specific energy and specific power should be in
increasing trend with a significant progress.

Supercapacitors are known for their rapid energy charge–discharge properties, often ten to a hundred times faster than batteries. However, there is still a demand for supercapacitors with even faster charge–discharge characteristics to... more

Supercapacitors are known for their rapid energy charge–discharge properties, often ten to a hundred times faster than batteries. However, there is still a demand for supercapacitors with even faster charge–discharge characteristics to fulfill the requirements of emerging technologies. The power and rate capabilities of supercapacitors are highly dependent on the morphology of their electrode materials. An electrically conductive 3D porous structure possessing a high surface area for ions to access is ideal. Using a flash of light, a method to produce highly interconnected 3D graphene architectures with high surface area and good conductivity is developed. The flash converted graphene is synthesized by reducing freeze-dried graphene oxide using an ordinary camera flash as a photothermal source. The flash converted graphene is used in coin cell supercapacitors to investigate its electrode materials properties. The electrodes are fabricated using either a precoating flash conversion or a postcoating flash conversion of graphene oxide. Both techniques produce supercapacitors possessing ultra-high power (5–7 × 105 W kg−1). Furthermore, optimized supercapacitors retain >50% of their capacitance when operated at an ultrahigh current density up to 220 A g−1.

With every moving day, the aspect that is going to be the most important for modern science and technology is the means to supply sufficient energy for all the scientific applications. As the resource of fossil fuel is draining out fast,... more

With every moving day, the aspect that is going to be the most important for modern science and technology is the means to supply sufficient energy for all the scientific applications. As the resource of fossil fuel is draining out fast, an alternative is always required to satisfy the needs of the future world. Limited resources also force to innovate something that can utilize the resource more efficiently. This work is based on a simple synthesis route of biomass-derived hard carbon and to exploring the possibility of using it as electrochemical supercapacitors. A cheap, eco-friendly and easily synthesized carbon material is utilized as electrode for electrochemical energy-storage. Four diferent hard carbons
were synthesized from KOH activated banana stem (KHC), phosphoric acid treated banana stem derived carbons (PHC), corn-cob derived hard carbon (CHC) and potato starch derived hard carbons
(SHC) and tested as supercapacitor electrodes. KOH-activated hard carbon has provided 479.23F/g specific capacitance as calculated from its cycle voltammograms. A detailed analysis is done to correlate
the results obtained with the material property. Overall, this work provides an in depth analysis of the science behind the components of an electrochemical energy-storage system as well as why the
diferent characterization techniques are required to assess the quality and reliability of the material for electrochemical supercapacitor applications.

Using the hybrid nanostructure and asymmetric configuration as strategies to enhance the capacitance of ZnO is demonstrated. A novel CNO-ZnO nanocomposite with unique nanoporous microstructure is used to achieve superior electrochemical... more

Using the hybrid nanostructure and asymmetric configuration as strategies to enhance the capacitance of ZnO is demonstrated. A novel CNO-ZnO nanocomposite with unique nanoporous microstructure is used to achieve superior electrochemical performance in an asymmetric configuration. The nanoporous morphology with well dispersed ZnO surface sites results in enhanced electrochemical activity through better electron transport and improved electrolyte accessibility in the nanocomposite. A binder-free, flexible asymmetric supercapacitor with nanoporous CNO-ZnO as negative and ZnO as positive is demonstrated to achieve high electrochemical performance. For the first time, an optimized CNO-ZnO//ZnO flexible asym-metric supercapacitor (ASC) is demonstrated in a stable operation voltage window of 1.8 V with a high energy and power density of 10 Wh/kg and 8100 W/kg, respectively. Furthermore, the CNO-ZnO//ZnO ASC device exhibits excellent long cycle life with retention of 92% specific capacitance after 2000 cycles. The overall device performance is attributed to their unique nanoporous microstructure, stable interface formation and interactive effect of constituent phases in the nanocomposite. From the overall findings, ZnO composites with carbon nano onions (CNO) can be a viable and potential choice for supercapacitor applications.

Functional electrically conductive fabric with acceptable mechanical properties, which could be applied in electromagnetic shielding, was developed. Conductive cotton fabrics (cotton/PANI, cotton/Mn, cotton/Cu, and cotton/Co) were... more

Functional electrically conductive fabric with acceptable mechanical properties, which could be applied in electromagnetic shielding, was developed. Conductive cotton fabrics (cotton/PANI, cotton/Mn, cotton/Cu, and cotton/Co) were prepared by in situ chemical oxidative polymerization for (cotton/PANI) and pad dry curing method was used for nanometals application. The Nano size of the metals and polyaniline inclusion were proven through both Dynamic Liquid Scattering (DLS) and X-ray diffraction (XRD) which showed an increase in crystallite density in unit space and the nano-particles ranged from 100-200 nm. The effect of gamma irradiation on different treated cotton fabrics was investigated. The mechanical properties against irradiation dose showed an improvement up to 40 kGy, for all treated fabrics. On the other hand, Young's modulus for untreated cotton recorded the lowest value, while cotton/Co recorded the highest one. Moreover, both AC (Alternating Current) and DC (Direct current) conductivities values can be calculated. In DC conductivity cotton/PANI was found to be more conducive than the remainder of the treated fabric by surface met-allization with transition metals; while in AC conductivity cotton/Mn was found to be more conducive than the rest of the treated samples. The conductivity value increases by increasing the gamma irradiation dose for cotton/PANI fabric. Also, g-factor values can be estimated from ESR signals and vary from 0.009 up to 0.059 for conductive

AS THE TITLE SAYS MORE SHORT PAPERS - SOUND BYTES.

Energy storage is a big problem today in the world for humanity depend on the challenges of conventional storage devices. So the researchers are studying to invent new energy storage devices and materials for many years. The... more

Energy storage is a big problem today in the world for humanity depend on the challenges of conventional storage devices. So the researchers are studying to invent new energy storage devices and materials for many years. The supercapacitor (SC) is invented and presented as an alternating storage device recently. There were a lot of studies about SC in literature. These studies are focused on materials of SC components, modelling of SC, and applications of SC. In this paper, the working principle of SC, the advantages of SC, the classification of SC, and new developments of SC are investigated. Some material applications of SC are presented in this study also. The manufacturing developments are investigated for some SC materials and presented some novel applications also.

The hybrid approach allows for a reinforcing combination of properties of dissimilar components in synergic combinations. From hybrid materials to hybrid devices the approach offers opportunities to tackle much needed improvements in the... more

The hybrid approach allows for a reinforcing combination of properties of dissimilar components in synergic combinations. From hybrid materials to hybrid devices the approach offers opportunities to tackle much needed improvements in the performance of energy storage devices. This paper reviews
the different approaches and scales of hybrids, materials, electrodes and devices striving to advance
along the diagonal of Ragone plots, providing enhanced energy and power densities by combining
battery and supercapacitor materials and storage mechanisms. Furthermore, some theoretical aspects
are considered regarding the possible hybrid combinations and tactics for the fabrication of optimized
final devices. All of it aiming at enhancing the electrochemical performance of energy storage systems

Alternative energy technologies are greatly hindered by significant limitations in materials science. From low activity to poor stability, and from mineral scarcity to high cost, the current materials are not able to cope with the... more

Alternative energy technologies are greatly hindered by significant limitations in materials science. From low activity to poor stability, and from mineral scarcity to high cost, the current materials are not able to cope with the significant challenges of clean energy technologies. However, recent advances in the preparation of nanomaterials, porous solids, and nanostructured solids are providing hope in the race for a better, cleaner energy production. The present contribution critically reviews the development and role of mesoporosity in a wide range of technologies, as this provides for critical improvements in accessibility, the dispersion of the active phase and a higher surface area. Relevant examples of the development of mesoporosity by a wide range of techniques are provided, including the preparation of hierarchical structures with pore systems in different scale ranges. Mesoporosity plays a significant role in catalysis, especially in the most challenging processes where bulky molecules, like those obtained from biomass or highly unreactive species, such as CO 2 should be transformed into most valuable products. Furthermore, mesoporous materials also play a significant role as electrodes in fuel and solar cells and in thermoelectric devices, technologies which are benefiting from improved accessibility and a better dispersion of materials with controlled porosity.

The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility.... more

The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors.

As per the present energy economics and environmental status, use of renewable energy resources is essential. The development of solar cell technology is from the first generation silicon solar cell to the emerging fourth generation "... more

As per the present energy economics and environmental status, use of renewable energy resources is essential. The development of solar cell technology is from the first generation silicon solar cell to the emerging fourth generation " Inorganics-inOrganic " solar cell. Various solar absorber compounds have been used for 2D solar cell manufacturing such as CdTe, Cu 2 InGaS 4 (CIGS), CIGSSe, Cu 2 ZnSnS 4 (CZTS) and CZTSSe. These compounds have more or less conversion efficiencies with some advantages and drawbacks. To overcome the drawbacks and achieve higher conversion efficiency, the efforts have been devoted. With some physical and chemical para-metric changes, researchers have got better results in the last ten years. In this review, the present research and development on the Cu 2 ZnSnS 4 thin film in the request of high efficiency solar cells is discussed. The effect of various structural and compositional change in the CZTS, different buffer layers with their interfaces, doping into the host material, partial substitution of the elements from the host, different synthesis and post treatments are thoroughly studied. In the last, the challenges regarding to improve conversion efficiency of CZTS solar cells and there future in the solar cell application are discussed.

SUMMARY In the last decades, fuel scarcity and increasing pollution level pave the way for an extensive interest in alternatives to petroleum-based fuels such as biodiesel, solar cells, lithium ion batteries, and supercapacitors. Among... more

SUMMARY In the last decades, fuel scarcity and increasing pollution level pave the way for an extensive interest in alternatives to petroleum-based fuels such as biodiesel, solar cells, lithium ion batteries, and supercapacitors. Among them, structural supercapacitors have been considered as promising candidates for automotive industries in present time. Herein, the use of carbon fiber-based supercapacitors in automotive applications is reviewed. Carbon fiber is an excellent candidate for vehicle body applications, and its composites could be widely used in the development of supercapacitors that could provide both structural and energy storage functions. Different surface modification processes of the carbon fiber electrode to enhance the electrochemical as well as mechanical performances are discussed. The advantages of the glass fiber separator and its comparison with other types of dielectric media have been incorporated. The synthesis procedures of the multifunc-tional solid polymer electrolyte and its significance have been also elaborated. The fabrication process, component selection , limitations, and future challenges of these supercapacitors are briefly assimilated in this review.

Electrochemical impedance spectroscopy (EIS) is an experimental method for characterizing electrochemical systems. This method measures the impedance of the concerned electrochemical system over a range of frequencies, and therefore the... more

Electrochemical impedance spectroscopy (EIS) is an experimental method for characterizing electrochemical
systems. This method measures the impedance of the concerned electrochemical system over
a range of frequencies, and therefore the frequency response of the system is determined, including
the energy storage and dissipation properties. The aim of this article is to review articles focusing on
electrochemical impedance spectroscopic studies and equivalent electrical circuits of conducting polymers,
such as polypyrrole, polycarbazole, polyaniline, polythiophene and their derivatives, on carbon
surfaces. First, the conducting polymers are introduced. Second, the electrochemical impedance spectroscopic
method is explained. Third, the results of EIS applications using equivalent electrical circuits for
conducting polymers taken from the literature are reviewed.

This paper presents the design of Low Drop-Out (LDO) voltage regulator has fast transient response and which exploits a few current else low quiescent current in the operational amplifier PMOS type. We use band-gap reference for eliminate... more

This paper presents the design of Low Drop-Out (LDO) voltage regulator has fast transient response and
which exploits a few current else low quiescent current in the operational amplifier PMOS type. We use
band-gap reference for eliminate the temperature dependence. The proposed LDO voltage regulator
implemented in 0.18-µm CMOS technology, we use Folded cascode CMOS amplifiers high performance in
the stability , provide fast transient response which explains a fast settling, the LDO itself should provide in
the output regulator voltages at ∆t equal 2ps with transient variation of the voltage less than 170mV. High
accuracy in the DC response terms, the simulation results show that the accuracy of the output regulator
voltages is 1.54±0.009V, and power consumption of 1.51 mW.

This review article focuses on electrochemical impedance spectroscopic study of thiophenes on carbon materials, the importance of which has been realized by recent progress in literature. The review article has 3 separate sections. In the... more

This review article focuses on electrochemical impedance spectroscopic
study of thiophenes on carbon materials, the importance of
which has been realized by recent progress in literature. The review
article has 3 separate sections. In the first part, most of the thiophene
derivatives (thiophene, 3-methylthiphene, 3-hexylthiophene, 3,4-
ethylenedioxythiophene, 3,4-propylenedioxythiophene, bithiophene,
octylthiophene, 3-dodecylthiophene, 3-terthiophene, 3-phenylthiophene,
3-methoxythiophene) and copolymers of thiophenes have been
reviewed. In the second part, carbon surfaces (carbon fiber microelectrode,
glassy carbon, carbon nanotubes, etc.) were used as effective
electrode materials. In the third part, the electrochemical
impedance spectroscopy (EIS) of thiophenes was explained with
supercapacitors and many different circuit modeling evaluations.

Galvanostatic deposition of tartrate–doped polypyrrole (PPy) is carried out on platinum foil in acetonitrile solution with tartaric acid, tetrabutylammonium tetrafluoroborate and Triton-X 100 for supercapacitor studies. The effect of... more

Galvanostatic deposition of tartrate–doped polypyrrole (PPy) is carried out on platinum foil in acetonitrile solution with tartaric acid, tetrabutylammonium tetrafluoroborate and Triton-X 100 for supercapacitor studies. The effect of substrate is studied by comparing the results obtained by using platinum, stainless steel and pencil graphite electrodes. The capacitive performance of the coatings are evaluated in an H2SO4/water medium by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge methods. Based on the charge–discharge results obtained, the tartrate–doped PPy coatings represent a high specific capacitance of 794 F g -1 (areal capacitance of 238 mF cm-2) and a high energy density of 105 Wh kg-1 on pencil graphite electrode, and a high power density of 36.3 kW kg-1 on 316Ti stainless steel electrode. High values may be attributed to the incorporation of tartaric acid via hydrogen bonding, and/or tartrate anion as dopant together with the tetrafluoroborate anion. Besides, Triton X100 provides high porosity and therefore high surface area.

The growing demand for clean energy storage and delivery during surge power applications motivate us to synthesize highly graphitic, mesoporous nitrogen-doped carbon nano-onions (NeCNOs) via a one-step in situ flame pyrolysis procedure... more

The growing demand for clean energy storage and delivery during surge power applications motivate us to synthesize highly graphitic, mesoporous nitrogen-doped carbon nano-onions (NeCNOs) via a one-step in situ flame pyrolysis procedure for their potential asymmetric supercapacitor (ASC) electrodes. The operating voltage of the fabricated ASC device is extended to 1.8 V in a 1 M Na 2 SO 4 electrolyte, yielding a maximum specific capacitance of 113 F g À1 and a high energy density of 51 Wh kg À1 at a current density of 4 A g À1. Importantly, even at a high current density of 20 A g À1 , the device still delivers a high power density of 18 kW kg À1 while maintaining an energy density of 6 Wh kg À1. Furthermore, the novel ASC exhibits excellent electrochemical cyclic stability over 10,000 cycles, retaining 98% of its specific capacitance and excellent coulombic efficiency of 99% at a high current density of 20 A g À1. The smaller characteristic relaxation time-constant (340 ms) than the previously reported graphene/MXene-based supercapacitors, validates the ultrahigh-rate ASC device-performance. These results confirm that N eCNOs can be used as a novel alternative electrode material in supercapacitors with high specific energy and power.

Carbon materials are widely used in supercapacitors because of their high surface area, controlled porosity and ease of processing into electrodes. The combination of carbon with metal oxides results in hybrid electrodes with higher... more

Carbon materials are widely used in supercapacitors because of their high surface area, controlled porosity and ease of processing into electrodes. The combination of carbon with metal oxides results in hybrid electrodes with higher specific capacitance than pure carbon electrodes, which has so far limited the energy density of supercapacitors currently available commercially. However, the preparation and processing of carbon/metal oxide electrodes into supercapacitors of different structures and configurations, especially for miniaturized electronics, has been challenging. Here, we demonstrate a simple one-step process for the synthesis and processing of laser-scribed graphene/RuO2 nanocomposites into electrodes that exhibit ultrahigh energy and power densities. Hydrous RuO2 nanoparticles were successfully anchored to graphene surfaces through a redox reaction of the precursors, graphene oxide, and RuCl3 using a consumer grade LightScribe DVD burner with a 788 nm laser. This binder-free, metal current collector-free graphene/RuO2 film was then used directly as a hybrid electrochemical capacitor electrode, demonstrating much-improved cycling stability and rate-capability with a specific capacitance up to 1139 F g−1. We employed these hybrid electrodes for building aqueous-based symmetric and asymmetric cells that can deliver energy densities up to 55.3 Wh kg−1, placing them among the best performing hybrid electrochemical capacitors. Furthermore, this technique was used for the direct writing of interdigitated hybrid micro-supercapacitors in a single step for the first time, with great potential for miniaturized electronics. This simple approach provides a general strategy for making a wide range of composite materials for a variety of applications.

Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the... more

Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the electron energy loss spectroscopy analysis, the reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V3G1 (VO/GO = 3:1), showed superior specific capacitance in comparison to the other composites (V1G1 and V1G3) and the pure materials. Moreover, the V3G1 composite showed excellent cyclic stability and the capacitance retention of about 82% was observed even after 5000 cycles.

For practical deployment of supercapacitors characterized by high energy density, power density and long cycle life, they must be realized using low cost and environmentally benign materials. Titanium dioxide (TiO 2) is largely abundant... more

For practical deployment of supercapacitors characterized by high energy density, power density and long cycle life, they must be realized using low cost and environmentally benign materials. Titanium dioxide (TiO 2) is largely abundant in the earth's crust; however, they show inferior supercapacitive electrochemical properties in most electrolytes for practical deployment. In this paper, we show that nickel doped TiO 2 (Ni:TiO 2) nanowires developed by electrospinning showed five times larger capaci-tance (~200 F g À1) than the undoped analogue (~40 F g À1). Electrochemical measurements show that the Ni:TiO 2 nanowires have 100% coulombic efficiency. The electrodes showed no appreciable capacitance degradation for over 5000 cycles. The superior charge storage capability of the Ni:TiO 2 could be due to its high electrical conductivity that resulted in five orders of magnitude higher ion diffusion as determined by cyclic voltammetry and electrochemical impedance spectroscopy measurements.

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials,... more

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are brie°y investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in speci¯c capacitance (SC) value as high as 135 Fg À1 . Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density.

In this work, we demonstrate the influence of nickel oxides with divergent particle sizes as the working electrodes for supercapacitor application. The nanostructured nickel oxide (NiO) is synthesized via facile sonochemical method,... more

In this work, we demonstrate the influence of nickel oxides with divergent particle sizes as the working
electrodes for supercapacitor application. The nanostructured nickel oxide (NiO) is synthesized via facile
sonochemical method, followed by calcination process. The crystallinity and surface purity of prepared
samples are clearly examined by X-ray diffraction and Raman analysis. NiO crystallinity is significantly
increased with increasing calcination temperatures. The surface analysis confirmed that the calcination
at 250 C exhibited nanoclutser like NiO with average particle size of 6 nm. While increasing the calcination
temperature beyond 250 C, hexagonal shaped NiO is observed with enhanced particle sizes. The
electrochemical performance confirmed the good redox behavior of NiO electrodes. Moreover, NiO with
average particle size of 6 nm exhibited high specific capacitance of 449 F/g at a scan rate of 5 mV/s compared
to other samples with particle sizes of 21 nm (323 F/g) and 41 nm (63 F/g). This is due to the
good ion transfer mechanism and effective electrochemical utilization of the working electrode.

A simple and scalable approach has been reported for V 2 O 5 encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized V 2 O 5 /MWCNTs electrode... more

A simple and scalable approach has been reported for V 2 O 5 encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized V 2 O 5 /MWCNTs electrode exhibited excellent charge-discharge capability with extraordinary cycling retention of 93% over 4000 cycles in liquid-electrolyte. Electrochemical investigations have been performed to evaluate the origin of capacitive behavior from dual contribution of surface-controlled and diffusion-controlled charge components. Furthermore, a complete flexible solid-state, flexible symmetric supercapacitor (FSS-SSC) device was assembled with V 2 O 5 /MWCNTs electrodes which yield remarkable values of specific power and energy densities along with enhanced cyclic stability over liquid configuration. As a practical demonstration, the constructed device was used to lit the 'VNIT' acronym assembled using 21 LED's. One dimensional (1D) carbon nanotubes (CNTs) are well-suited for supercapacitor applications due to their great conductive nature, porous surface area, and high aspect ratio. However, improved performances could be gained by encapsulating its surface with other electroactive materials, like transition metal oxides (TMOs). The resulting hybrid electrodes can feature dual supercapacitive behavior, as electric double layer along with pseudocapacitive from TMOs. Furthermore, TMOs possess an unmatched combination of properties like unique morphology and stability at wider temperature range that brand them superior to polymers towards supercapacitor application 1,2. Amongst metal oxides, ruthenium oxide (RuO 2) got much attention in past decades because of its reversible oxidation states and great electrical conductivity. Zhang et al. 3 were able to attain a high specific capacitance of 860 F g −1 for tubular ruthenium oxide. On the other hand, RuO 2 is rare, expensive and most importantly toxic, which deters as supercapacitor material 4 and hence, research on alternative TMOs electrode materials is of great importance. Layered V 2 O 5 has gained much interest due to its multiple valance states responsible to deliver high specific energy based on intercalation/deintercalation of electrolyte ions 5 , but its final performance differs greatly depending on the synthetic route and the phase obtained. Sol-gel derived nanoporous V 2 O 5 attains capacitance of 214 F g −1 in 2 M KCl 6 whereas the same electrolyte at the same concentration through co-precipitation method yields 349 F g −1 specific capacitance 7,8. Instead of using just the metal oxide, nanocomposites with MWCNTs will further boost the electrochemical properties of the resulting electrodes. A series of different metal oxide/ MWCNTs composites have been used as electrode. Many strategies are auctioned to trigger the supercapacitor performance of V 2 O 5 with the tools such as synthesis method, morphology and so forth. Kim et al. 9 improved

Supercapacitors with aqueous electrolytes and nanostructured composite electrodes are attractive because of their high charging-discharging speed, long cycle life, low environmental impact and wide commercial affordability. However, the... more

Supercapacitors with aqueous electrolytes and nanostructured composite electrodes are attractive because of their high charging-discharging speed, long cycle life, low environmental impact and wide commercial affordability. However, the energy capacity of aqueous supercapacitors is limited by the electrochemical
window of water. In this paper, a recently reported engineering strategy is further developed and demonstrated to correlate the maximum charging voltage of a supercapacitor with the capacitive potential ranges and the capacitance ratio of the two electrodes. Beyond the maximum charging voltage, a supercapacitor may still operate, but at the expense of a reduced cycle life. In addition, it is shown that the supercapacitor performance is strongly affected by the initial and zero charge potentials of the electrodes. Further, the differences are highlighted and elaborated between freshly prepared, aged under open circuit conditions, and cycled electrodes of composites of conducting polymers and carbon nanotubes. The first voltammetric charging-discharging cycle has an electrode conditioning effect to change the electrodes from
their initial potentials to the potential of zero voltage, and reduce the irreversibility.

The electrochemical characteristics of supercapacitors consisting of molybdenum carbide derived carbon C(Mo2C) electrodes in 1M NaPF 6 solutions in various mixtures (0.5–5%) of vinylene carbonate (VC) with propylene carbonate (PC) and... more

The electrochemical characteristics of supercapacitors consisting of molybdenum carbide derived carbon C(Mo2C) electrodes in 1M NaPF 6 solutions in various mixtures (0.5–5%) of vinylene carbonate (VC) with propylene carbonate (PC) and ethyl acetate (EA) (1:1 by volume) have been studied using cyclic voltammetry, constant current charging/discharging and electrochemical impedance spectroscopy methods. The specific capacitance and series resistance values dependencies on the used solvent mixture and applied temperature (from −40 • C to 60 • C) have been established. The region of ideal polarizability has been established for C(Mo 2 C) electrodes in all electrolytes and temperatures investigated, except at T ≥ 40 • C. Specific conductivity values have been measured and correlated with electrochemistry data. Limiting capacitance, calculated characteristic time constant and complex power values depend noticeably on the solvent mixture used in the electrolyte, i.e. on the viscosity and specific conductivity of the electrolyte solution. The studied electrolytes are potential candidates for low-temperature supercapacitors.

Recently, enhancement of the energy density of a supercapacitor is restricted by the inferior capacitance of negative electrodes, which impedes the commercial development of high-performance symmetric and asymmetric supercapacitors. This... more

Recently, enhancement of the energy density of a supercapacitor is restricted by the inferior capacitance of negative electrodes, which impedes the commercial development of high-performance symmetric and asymmetric supercapacitors. This article introduces the in situ bulk-quantity synthesis of hydrophilic, porous, graphitic sulfur-doped carbon nano-onions (S-CNO) using a facile flame-pyrolysis technique and evaluated its potential applications as a high-performance supercapacitor electrode in a symmetric device configuration. The high-surface wettability in the as-prepared state enables the formation of highly suspended active conducting material S-CNO ink, which eliminates the routine use of binders for the electrode preparation. The as-prepared S-CNO displayed encouraging features for electrochemical energy storage applications with a high specific surface area (950 m2 g–1), ordered mesoporous structure (∼3.9 nm), high S-content (∼3.6 at. %), and substantial electronic conductivity, as indicated by the ∼80% sp2 graphitic carbon content. The in situ sulfur incorporation into the carbon framework of the CNO resulted in a high-polarized surface with well-distributed reversible pseudosites, increasing the electrode–electrolyte interaction and improving the overall conductivity. The S-CNOs showed a specific capacitance of 305 F g–1, an energy density of 10.6 W h kg–1, and a power density of 1004 W kg–1 at an applied current density of 2 A g–1 in a symmetrical two-electrode cell configuration, which is approximately three times higher than that of the pristine CNO-based device in a similar electrochemical testing environment. Even at 11 A g–1, the S-CNO||S-CNO device rendered an energy density (6.1 W h kg–1) at a deliverable power density of 5.5 kW kg–1, indicating a very good rate capability and power management during peak power delivery applications. Furthermore, it showed a high degree of electrochemical reversibility with excellent cycling stability, retaining ∼95% of its initial capacitance after more than 10 000 repetitive charge–discharge cycles at an applied current density of 5 A g–1.

h i g h l i g h t s g r a p h i c a l a b s t r a c t High capacitance and power density of coarse-grained porous carbon supercapacitors. Lower synthesis and manufacturing costs. Greater mass loading for grid and automotive electrical... more

h i g h l i g h t s g r a p h i c a l a b s t r a c t High capacitance and power density of coarse-grained porous carbon supercapacitors. Lower synthesis and manufacturing costs. Greater mass loading for grid and automotive electrical energy storage. Superior performance than activated carbon in different electrolytes. Expanded operating voltage window.

Lithium based battery type supercapacitors has replaced the batteries for electric energy storage. A novel improved occurs in energy density and the electrodes carried the good electrochemical performances of specific capacitance,... more

Lithium based battery type supercapacitors has replaced the batteries for electric energy storage. A novel improved
occurs in energy density and the electrodes carried the good electrochemical performances of specific capacitance,
charge-discharge, high power density and high life cycle. In this paper describes, the lithium combined with metal/
transition metal oxides/ carbon based material or conducting polymer as an electrode in the lithium based battery
type supercapacitors. In addition, to that this cathode material has synthesized in different methods and mention
with their characterization, electrochemical performances and applications from the literatures.

The rapid development of miniaturized electronic devices has increased the demand for compact on-chip energy storage. Microscale supercapacitors have great potential to complement or replace batteries and electrolytic capacitors in a... more

The rapid development of miniaturized electronic devices has increased the demand for compact on-chip energy storage. Microscale supercapacitors have great potential to complement or replace batteries and electrolytic capacitors in a variety of applications. However, conventional micro-fabrication techniques have proven to be cumbersome in building cost-effective micro-devices, thus limiting their widespread application. Here we demonstrate a scalable fabrication of graphene micro-supercapacitors over large areas by direct laser writing on graphite oxide films using a standard LightScribe DVD burner. More than 100 micro-supercapacitors can be produced on a single disc in 30 min or less. The devices are built on flexible substrates for flexible electronics and on-chip uses that can be integrated with MEMS or CMOS in a single chip. Remarkably, miniaturizing the devices to the microscale results in enhanced charge-storage capacity and rate capability. These micro-supercapacitors demonstrate a power density of ~200 W cm−3, which is among the highest values achieved for any supercapacitor.

Super capacitor power bank is a charge storage device composed of normal electrolytic capacitors. As the name suggests it can perform exactly like a charge storage cell. In addition to that it can provide multiple output power options and... more

Super capacitor power bank is a charge storage device composed of normal electrolytic capacitors. As the name suggests it can perform exactly like a charge storage cell. In addition to that it can provide multiple output power options and LDO output for small power applications. The charging and discharging time is one of the crucial factors in the calculation of charge in the device. The charging time of the capacitor is very small and discharging time will be very high. Since we can block the discharging path then the discharging time can be increased to two to three days. The main advantages of the system are less weight, easy to handle and multiple power options. The function of LDO is to provide sustained low drop voltage for low power applications.

In the present study, molybdenum diselenide/reduced graphene oxide (MoSe 2 /rGO) nanosheets were synthesized via a facile hydrothermal process and the electrochemical performance of the nanosheets was evaluated for supercapacitor... more

In the present study, molybdenum diselenide/reduced graphene oxide (MoSe 2 /rGO) nanosheets were synthesized via a facile hydrothermal process and the electrochemical performance of the nanosheets was evaluated for supercapacitor applications. The MoSe 2 nanosheets were uniformly distributed on the surface of the rGO matrix. The MoSe 2 /rGO nanosheet electrode exhibited an enhanced specific capaci-tance (211 F g −1) with excellent cycling stability, compared with pristine MoSe 2. The enhanced electro-chemical performance of the MoSe 2 /rGO nanosheet electrode is mainly attributed to the improved electron and ion transfer mechanism involving the synergistic effects of pseudocapacitance (from the MoSe 2 nanosheets) and the electric double layer charge (EDLC, from the rGO nanosheets) storage behavior. These results demonstrate that the enhanced electrochemical performance of MoSe 2 /rGO nanosheets could be obtained via a facile and scalable approach.

This paper provides a State of Charge Analysis of 40F and 400F Supercapacitor Bank for small scale off-gird energy storage. In addition, A detailed analysis of the bank starting from charging cycles, flowed by discharging graph for a... more

This paper provides a State of Charge Analysis of 40F and 400F Supercapacitor Bank for small scale off-gird energy storage. In addition, A detailed analysis of the bank starting from charging cycles, flowed by discharging graph for a small scale load have been provided. The summary result specifically indicates rapid increase of SoC curve increase rapidly upto 3V with state of charge is 20% and rest of all increase linearly up to maximum level for 40F Supercapacitor Bank. Consequently, an increase in proportion to voltage, the SoC curve takes a sharp increase up to 4V with state of charge is 18% and rest of all increase linearly up to maximum level for 400F Supercapacitor bank.

We investigated different molar concentrations of cobalt precursor intercalated reduced graphene oxide (rGO) as possible electrode materials for supercapacitors. Cobalt oxide (Co 3 O 4) nanocubes intercalated reduced graphene oxides (rGO)... more

We investigated different molar concentrations of cobalt precursor intercalated reduced graphene oxide (rGO) as possible electrode materials for supercapacitors. Cobalt oxide (Co 3 O 4) nanocubes intercalated reduced graphene oxides (rGO) were synthesized via a facile hydrothermal method. It has been found that the Co 3 O 4 particles with a cubical shape are decorated on rGO matrix with an average size of $45 nm. The structural crystallinity of rGO–Co 3 O 4 composites was examined by X-ray diffraction (XRD). Raman spectroscopy confirmed the successful reduction of GO to rGO and effective interaction between Co 3 O 4 and the rGO matrix. The electrochemical performances of rGO–Co 3 O 4 electrodes were examined using cyclic voltammetry and charge–discharge techniques. The maximum specific capacitance (278 F g À1) is observed at current density of 200 mA g À1 in the C2 electrode resulting from effective ion transfer and less particle aggregation of Co 3 O 4 on the rGO matrix than in the other electrodes. C2 exhibits good rate capability and excellent long-term cyclic stability of 91.6% for 2000 cycles. The enhanced electrochemical performance may result from uniform intercalation of cobalt oxide over the rGO. These results suggest that the Co 3 O 4 intercalated rGO matrix could play a role in improved energy storage capability.

Hetero-structured manganese dioxide nanorods with α phase (α–MnO2) were prepared by a facile hydrothermal route at low temperature. X–ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen... more

Hetero-structured manganese dioxide nanorods with α phase (α–MnO2) were prepared by a facile hydrothermal route at low temperature. X–ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements were used to characterize the properties of prepared hetero-structured α–MnO2 nanorods. Supercapacitive performance of the hetero-structured α–MnO2 nanomaterials as active electrode material was evaluated by cyclic voltammetry (CV) in alkaline media. The MnO2 hetero-structure with 2 x 2 tunnels constructed from double chains of octahedral [MnO6] structure yield a significantly high specific capacitance of 298 Fg-1 at 5mVs-1 and demonstrated a superior long term cyclic stability, with specific capacitance retention about 94% after 1000 cycles. The superior supercapacitive performance of the hetero-structured α–MnO2 electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

A B S T R A C T Asymmetric supercapacitors (ASCs) are routinely fabricated using battery-type electrode materials as a positive electrode and electrochemical double layer materials as a negative electrode; the mass-loading in the... more

A B S T R A C T Asymmetric supercapacitors (ASCs) are routinely fabricated using battery-type electrode materials as a positive electrode and electrochemical double layer materials as a negative electrode; the mass-loading in the electrodes is determined by assuming both to be capacitive charge storage materials. This protocol is erroneous as the cyclic voltammograms and galvanostatic charge-discharge curves of the resulting devices showed dissimilarity in the stored charges of the two electrodes and battery-type behaviors, respectively. Herein, we show by employing two choices of battery-type electrodes as positive electrodes and commercial activated carbon as negative electrode in 3 M LiOH electrolyte that equal mass loading in both electrodes leads to supercapacitive charge storage. The positive electrode to negative electrode mass ratio is varied from 0.75 to 1.5 in a mass interval of 0.25 which includes a mass ratio of the conventional method. The electrochemical studies of the fabricated ASCs show that the charge storage capabilities depend on the electrode mass. Electrochemical impedance spectroscopy studies show that the equal mass ratio has low series and charge transfer resistances and wider frequency dispersion of capacitance.

Casuarina equisetifolia wood is extensively used as fire wood and is also being used extensively in gassifiers. Drying is an important procedure which has to be carried out before the wood is burnt. Experiments on Casuarina wood chips of... more

Casuarina equisetifolia wood is extensively used as fire wood
and is also being used extensively in gassifiers. Drying is an
important procedure which has to be carried out before the
wood is burnt. Experiments on Casuarina wood chips of dimension
5.08 cm × 5.08 cm with 2.54 cm thickness were carried out
between 80o
C to 100o
C in a tray drier using air flow velocity
of 0.5m/s. Initial moisture content was found to be 48% on dry
basis. The experimental drying curves showed only the falling
rate period. Eleven thin-layer drying kinetic models were fitted
with the experimental drying kinetics values and individual
model constants were found. These models were compared
using statistical measures like correlation coefficient, root
mean square error, mean bias error and reduced chi-square to
estimate the best model that would fit for the experiment. The
drying rate and effective diffusion coefficient (Deff) were found
to increase with temperature.

Electrochemical double layer capacitors (EDLCs) are investigated with activated carbon electrodes and a lithium-ion electrolyte, in anticipation of potential future applications in hybridised battery-supercapacitor devices and lithium ion... more

Electrochemical double layer capacitors (EDLCs) are investigated with activated carbon electrodes and a lithium-ion electrolyte, in anticipation of potential future applications in hybridised battery-supercapacitor devices and lithium ion capacitors. An experimental study of a symmetric electrochemical double layer capacitor (EDLC) with activated carbon (AC) electrodes on aluminium foil current collectors and electrolyte 1 M LiPF6 in EC:EMC 50:50 v/v concludes a stability window to a maximum potential of 3 V, an equivalent in series resistance of 48 Ω for 1 cm² cell area (including the contact resistance between electrode and current collector) and an average specific electrode capacitance of 50.5 F g⁻¹. Three AC electrode materials are assessed via computer simulations based on a continuum ion and charge transport model with volume-averaged equations, considering the pore size distribution for each electrode material and, depending on pore size, transport of tetrahedral solvated or flat solvated Li⁺ ions and solvated or desolvated PF6⁻ ions. The computer simulations demonstrate that the best electrode material is an AC coating electrode with a hierarchical pore size distribution measured in the range of 0.5–180 nm and bimodal shape, and specific surface area BET = 808 m² g⁻¹.

This paper highlights suitability of three dimensional (3D) network composed of manganese oxide nanofibers (NF-MnO 2 ), synthesized by the potentiodynamic electrodeposition for supercapacitor application. Electrodeposition mechanism of... more

This paper highlights suitability of three dimensional (3D) network composed of manganese oxide nanofibers (NF-MnO 2 ), synthesized by the potentiodynamic electrodeposition for supercapacitor application. Electrodeposition mechanism of manganese oxide is discussed with the help of electrochemical quartz crystal microbalance (EQCM) study and it reveals that maximum mass deposited on the electrode surface occurs at 0.85 V vs SCE. The FE-SEM images exhibit an interconnected 3-D network composed of MnO 2 nanofibers with diameter varies from 10 to 27 nm and length of the order of 0.1 to 0.5 mm, exhibiting high aspect ratio. XPS measurements revealed that the peak appeared at binding energies of 642.6 and 654.05 eV attributed to the Mn 4+ state in the NF-MnO 2 . The maximum specific capacitance of 392F.gAˋ1at10mV.sAˋ1byusingcyclicvoltammetry(CV)and383F.gAˋ1atacurrentdensityof2mA.cmAˋ2bychargedischargestudieswereachievedfortheNF−MnO2inanelectrolyteof1MNa2SO4.TheNF−MnO2exhibitsanexcellentratecapabilitywithhighspecificenergyof392 F.g À1 at 10 mV.s À1 by using cyclic voltammetry (CV) and 383 F.g À1 at a current density of 2 mA.cm À2 by charge discharge studies were achieved for the NF-MnO 2 in an electrolyte of 1 M Na 2 SO 4 . The NF-MnO 2 exhibits an excellent rate capability with high specific energy of 392F.gAˋ1at10mV.sAˋ1byusingcyclicvoltammetry(CV)and383F.gAˋ1atacurrentdensityof2mA.cmAˋ2bychargedischargestudieswereachievedfortheNFMnO2inanelectrolyteof1MNa2SO4.TheNFMnO2exhibitsanexcellentratecapabilitywithhighspecificenergyof48.74 Wh.kg À1 and specific power of $2.12 kW.kg À1 . The high specific capacitance and charge-discharge rates offered by NF-MnO 2 make them promising candidates for supercapacitor electrodes, combining high-energy densities with high levels of power delivery.

Flower shaped birnessite type manganese oxide (d-MnO 2 ) nanostructures are synthesized using a simple hydrothermal process with an aim to fabricate high performance supercapacitors for energy storage electrode. The studies reveal that... more

Flower shaped birnessite type manganese oxide (d-MnO 2 ) nanostructures are synthesized using a simple hydrothermal process with an aim to fabricate high performance supercapacitors for energy storage electrode. The studies reveal that layered d-MnO 2 had a basal plane spacing of 0.73nmandarecomposedofthinnanosheetsofthickness0.73 nm and are composed of thin nanosheets of thickness 0.73nmandarecomposedofthinnanosheetsofthickness23 nm. A detailed investigation is undertaken to draw a relationship between the solvated ion size of alkaline electrolytes (LiOH, NaOH and KOH) and pore size in the electrode material favoring high specific capacitance and faster electrode kinetics. The present work not only develops a high performance supercapacitive material but also identifies that by suitably tuning the sizes of solvated ion and the pores, supercapacitive behavior of a single material system can be tailored.

Supercapacitors are an emerging choice for energy buffering in field systems and their use in solar-powered field systems has been the focus of recent research. Supercapacitors offer advantages compared to rechargeable batteries for... more

Supercapacitors are an emerging choice for energy buffering in field systems and their use in solar-powered field systems has been the focus of recent research. Supercapacitors offer advantages compared to rechargeable batteries for energy buffering due to their energy charge/discharge efficiency as well as environmental friendliness. Additionally, a supercapacitorbased system permits an energy-aware operation due to its superior energy-predictability. This paper describes a circuit for solar/supercapacitor energy harvesting, which includes power and voltage measurements, voltage regulation circuit and RS232 communication capability with the host embedded processor. A complete system is prototyped and its operation is discussed in terms of design parameters.

A capacitor is a passive electronic component that stores energy in the form of an electrostatic field. In its simplest form, a capacitor consists of two conducting plates separated by an insulating material called the . The capacitance... more

A capacitor is a passive electronic component that stores energy in the form of an electrostatic field. In its simplest form, a capacitor consists of two conducting plates separated by an insulating material called the . The capacitance is directly proportional to the surface areas of the plates, and is inversely proportional to the separation between the plates. Capacitance also depends on the dielectric constant of the substance separating the plates.

Continuous processes in the plastics, textile paper and other industries, require several drives working in synchronism. The aim of this paper is to control speed of the winding system, and to maintain a constant mechanical tension... more

Continuous processes in the plastics, textile paper and other industries, require several drives working in synchronism. The aim of this paper is to control speed of the winding system, and to maintain a constant mechanical tension between the rollers of the system. Several controllers are considerer, including sliding-mode control (SMC) single input/single output (SISO) and SMC multi input/multi output (MIMO) and Proportional-integral (PI/MIMO) . Since the PI control method can be applied easily and is widely known, it has an important place in control applications. But this method is insensitive to parameter changes. The advantage of an SMC is its robustness and ability to handle the non-linear behaviour of the system. The main contribution of this paper consists of designing MIMO sliding mode control law of a distributed parameter based on the original model for which the control variables are coupled. The performances of the control law are illustrated by means of simulations and compared to previous results obtained by SISO and (PI-MIMO) control laws.