Characteristics Of Supercapacitors Research Articles

Carbon cloth supported flower-like porous nickel-based electrodes boosting ion/charge transfer characteristics of flexible supercapacitors

Despite low cost and high theoretical specific capacitances, nickel-based compounds still suffer from poor conductivity, limited redox active sites and sluggish ion and charge transfer for their applications in flexible supercapacitors (FSCs). The rational structural control of nickel-based compound electrodes is vital but very challenging. Herein, a series of flower-like nickel-based compound electrodes are grown on carbon cloth (CC) by a general synthetic method, including Ni(OH)2/CC, NiS2/CC, NiO/CC and Ni2P/CC hybrid electrodes. The formation mechanism of such flower-like structure is investigated in-depth. Benefiting from the fibrous structure of flexible carbon cloth and flower-like porous structure of NiS2, the NiS2/CC hybrid electrodes are more accessible for the electrolyte ions, which facilitates their electrochemical kinetics and capacitive performances. The maximum specific capacitance of the NiS2/CC electrode is 1166.3 F/g at 0.4 A/g. Moreover, flexible asymmetric supercapacitors (FASCs) are assembled using NiS2/CC and activated carbon/CC (AC/CC) as positive and negative electrodes, respectively. Such FASCs exhibit an energy density of 34.1 Wh/kg at a power density of 561.3 W/kg, a long lifetime stability (96% retention after 8,000 cycles), and excellent mechanical stability. These superior electrochemical characteristics make the flower-like porous NiS2/CC hybrid a good candidate for next-generation flexible and high-performance electrode in FSCs.

Thermal characteristic and performance influence of a hybrid supercapacitor

The working performance of hybrid supercapacitor was comprehensively studied. The electrothermal coupling and thermal characteristics of hybrid supercapacitor were discussed. The influences of operation parameters, such as ambient temperature, electrode thickness, thickness ratio of anode to cathode electrodes were examined. The heat generation rate, temperature distribution and working performance of hybrid supercapacitor were analyzed during charge-discharge. The results show that a higher ambient temperature, a greater charge-discharge current, and a thicker cathode electrode will lead to much more obvious temperature rise. Consequently, the high-temperature accumulation effect on the central area of hybrid supercapacitor easily occurs. The low ambient temperature will cause capacitance attenuation, while the equivalent series internal resistance increases greatly. When the ambient temperature is the same, the cathode-electrode thickness will affect the sensitivity of a hybrid supercapacitor. The charge-discharge time increases with the increase of cathode electrode thickness, the average state of charge decreases with the increasing of cathode electrode thickness, the extraction-insertion of lithium ions are happened from the anode electrode, the capacitance of hybrid supercapacitor will finally increase. The average energy density can be significantly improved by increasing cathode-electrode thickness. However, the equivalent series resistance and heat production simultaneously increase, so the power density decreases eventually.

Synergistic and capacitance effects in nanocarbon based capacitor batteries designed for superior rate capability and long-cycle stability

Existing lithium-ion batteries struggle to achieve high-rate discharge stability. To address this problem, this study combines resin-based carbon nanospheres with a double electric layer effect and cathode materials with lithium-ion intercalation/delithiation behavior to form a LiNi0.6Co0.2Mn0.2O2/resin-based carbon-sphere hybrid electrode. For further improvement in electron contact and tap density, the size of the carbon nanospheres was controlled by changing the synthetic parameters, and a size-matched spatial structure model of each component within the hybrid electrode was constructed. Considering the excellent rate capability of small-sized hard carbon, hard-carbon nanospheres derived from glucose were employed as the anode active material to assemble a capacitor battery. With the integration of characteristics of both lithium-ion batteries and supercapacitors, the as-prepared new capacitor battery exhibited a specific capacity of 146.1 mAh/g at 0.1C and an energy density of 474.5 Wh/kg on the cathode active material mass, a reversible capacity of 113.2 mAh/g at 1C after 200 cycles with retention of 85.3%, and the capacity remained at 82 mAh/g even at a high current rate of 10C. These results offer insights into the design of energy storage devices with excellent cycling stability and rate capability.

Modeling and simulation analysis of electric forklift energy prediction management

In recent years, the effective utilization of energy for electric forklift has been the focus of research. However, the load of forklift change markedly and frequently, leading to a great challenge in the performance of the composite energy system. To solve this problem, this paper presents the power system structure of electric forklift and the battery–supercapacitor hybrid energy management method of electric forklift truck. The working conditions and energy flow of electric forklift are analyzed and the power demand forecasting model of electric forklift power system is indispensable. Two predictive control based on Markov chain and neural network are developed, considering the performance of predictive control. The predictive model is applied to the stochastic model predictive (SMPC) energy management strategy. Simulations are carried out on the representative driving cycles of an electric forklift. As an auxiliary power supply on the energy management of composite power, the influence of the development depth of supercapacitor is discussed. Simulation results show that short-term Markov chain model is closer to the actual working condition. Fuzzy neural network model can give full play to the charging and discharging characteristics of supercapacitors. The state of charge of supercapacitor is stable between 0.5 and 1, which effectively stabilizes the rate of the charge and discharge of the battery.

Electrochemical Characteristics of Zn-Ion Hybrid Supercapacitors Based on Aqueous Solution of Different Electrolytes

Electrochemical behaviour of Zn cation based various aqueous electrolytes (ZnSO4, Zn(BF4)2, zinc di[bis(trifluoromethylsulfonyl)imide], Zn(TFSI)2, and zinc trifluoromethanesulfonate, Zn(OTf)2) has been studied in thin Zn foil∣ carbon cloth hybrid supercapacitor cell and compared with Zn(ClO4)2 aqueous electrolyte electrochemical characteristics using cyclic voltammetry, constant current charge/discharge and electrochemical impedance methods. The Ragone plots have been calculated from constant power measurements data. At moderate specific power values (10 kW kg−1) noticeable decrease of specific energies can be seen in the order of electrolytes: Zn(ClO4)2 ≥ Zn(BF4)2 > Zn(OTf)2 > Zn(TFSI)2 > ZnSO4. The stability of Zn-ion hybrid supercapacitor cells under study has been tested using the long lasting (up to 10000 cycles) constant current charge/discharge method and is very good for Zn(OTf)2, Zn(ClO4)2 and ZnSO4.

Statistical modeling of hybrid supercapacitor

Energy helps machines to work as per human requirements. Energy can be in any form such as solar energy, wind energy, geo thermal energy and many more. However, utilization of energy depends on application requirements, energy converters, source of energy and most important energy storage system. Some energy storage devices are required that stores the energy from various forms and gives it to load as and when required. Battery, fuel cell and supercapacitor are the examples of it. However, there is need of better electrical energy storage device. Hybrid supercapacitor can replace some of them in near future. Modeling of hybrid supercapacitor could play a significant role to achieve desired characteristics. Hybrid supercapacitor possesses characteristics of both battery and supercapacitor. Modeling of this device can be a game-changer in the energy sector as it will give full insight of issues in it. Statistical modeling can help in getting single device that can replace externally connected battery-supercapacitor combinations. Statistical modeling of the hybrid supercapacitor has been carried out with the most significant input factors related to electrodes and specific capacitance as an output parameter.

Insight into the Supercapacitive Behavior of Activated Hollow Porous Carbon Spheres in Different Electrolytes

Supercapacitive behaviors of the porous carbon electrode principally depend on the properties of electrolyte. In this paper, activated hollow porous carbon spheres (AHPCSs) with large specific areas were prepared by the hydrothermal method and subsequent one-step KOH activation treatment. The electrochemical performances and supercapacitive characteristics of the AHPCS supercapacitors were evaluated in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid electrolyte, 1 mol L–1 LiPF6 organic electrolyte, and 6 mol L–1 KOH aqueous electrolyte. It has been found that the supercapacitors with AHPCS electrode have definitely good supercapacitive behaviors in the three electrolytes. Especially, the AHPCS supercapacitor in the EMIMBF4 ionic liquid electrolyte that has a wide operating voltage of 0–3.0 V exhibits an excellent rate performance with capacitance retention of 72.3% from 0.5 to 10 A g–1 and a good cycle performance with a high capacitance retention of 94.2% after 4000 consecutive cycles. Moreover, it obtains a high energy density of 80.5 Wh kg–1 at 750 W kg–1, which transcends most of the currently reported carbon-based supercapacitors. Therefore, the supercapacitors with EMIMBF4 ionic liquid as electrolyte and AHPCSs as active electrode materials show tremendous potential in terms of boosting comprehensively electrochemical performance.

Research on electric vehicle‐supercapacitor hybrid system participates in the application of tracking PV project output

AbstractWith the increase in new energy power generation and the continuous augment in the penetration rate of electric vehicles, it is of crucial importance to use electric vehicles as energy storage devices to promote the consumption of new energy. Aiming at the uncertainty of electric vehicles, this paper proposes a method based on multiobjective optimization for electric vehicle‐supercapacitor hybrid energy storage system to track PV project output. The hybrid system consists of electric vehicles and supercapacitor. Electric vehicles and supercapacitors supplement the deviation of PV actual power and predicted power by charging and discharging. The electric vehicle is regarded as a nonspecific way to label a piece of equipment that can store energy. First and foremost, on the basis of traditional method of predicting PV output, a PSO‐BP prediction method based on PCA is proposed to improve the accuracy of PV output prediction. Secondarily, according to the different characteristics of electric vehicles and supercapacitors, the empirical mode decomposition (EMD) method is used to decompose the deviation that the hybrid energy storage system needs to bear with the purpose of initially allocating the energy. Furthermore, a multiobjective optimization model is established for the precise energy distribution of the hybrid energy storage system, and the NSGA‐III algorithm is used to solve it. Ultimately, the data of a domestic PV power station are used for simulation. After optimized control, the result shows that the standard deviation of the system output is reduced from 1967 to 75.77. The research in this article provides a theoretical basis for the application of electric vehicle virtual energy storage technology in the field of auxiliary new energy grid connection.

The Effect of Aqueous Electrolyte Molarity on the Characteristics of Supercapacitor with Electrodes Based on Carbon Materials

The Effect of Aqueous Electrolyte Molarity on the Characteristics of Supercapacitor with Electrodes Based on Carbon Materials

Fabrication of aqueous solid-state symmetric supercapacitors based on self-healable poly (acrylamide)/PEDOT:PSS composite hydrogel electrolytes

The composite hydrogel electrolytes developed from conducting polymers own superb/excellent conductive, self-healing, and mechanical properties. However, it is still challenging to exploit them in energy storage devices. To address this issue, novel poly(acrylamide)/poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) composite hydrogel electrolytes were developed through free radical polymerization in which sodium montmorillonite clay was added as a physical crosslinker. The different amounts of PEDOT:PSS were added to the composite hydrogel electrolytes. The structure of the synthesized composite hydrogel electrolytes was investigated by X-ray diffraction (XRD) analysis. The surface morphology of the composite hydrogel electrolyte was examined with the field emission scanning electron microscopy (FESEM) and elemental composition was determined using energy-dispersive X-ray spectroscopy (EDX). The ionic conductivity was measured at ambient temperature. Among the synthesized electrolytes, PEDOTAAM34 achieved the highest ionic conductivity of 13.7 × 10−3 S/cm at room temperature. Furthermore, electrochemical studies were performed by sandwiching the composite hydrogel electrolytes between symmetric carbon-coated graphite electrodes. The fabricated AC/PEDOTAAM34/AC based symmetric supercapacitor attained the highest specific capacitance of 327 F/g at 3 mV/s and 385.4 F/g (energy density of 53.57 Wh/kg at a power density of 100.08 W/kg) at 100 mA/g current density. The self-healable characteristics of symmetric supercapacitors were confirmed by powering up a light-emitting diode (LED).

Reliable and precise evaluation energy-transfer and efficiency of super-capacitors

This article presents a basic physics model for the extraction of the potential-time characteristics of super-capacitors during charging and discharging that specifically accounts for the unique contributions to the power source and their nonlinear behaviors. The essential feature of the proposed extraction method is that it is based on the physical phenomena underlying the electrical characteristics of super-capacitors, this phenomenology model describes the essential features of the potential–time characteristics of the super-capacitors which can then be fit to any physics-based super-capacitor system. There are only three parameters in this elementary physics model and the model is expressed in the form of an explicit function. The best result is that the integral of the model over time results in an explicit function which corresponds to the input and the output energy. There is great beneficial to both super-capacitor designers and industry. The experimental validation of the new model agrees well with the measurements. To avoid confusion in weighing in super-capacitor performance, energy-transfer efficiency is introduced. Experimental and theoretical results show that the minimum energy-transfer efficiency is neither at the maximum current density nor at the minimum current density. We hope, by using this energy-transfer efficiency, the existing inconsistencies and confusion in the evaluation of the super-capacitor performance can be dispelled so as to help facilitate further progress in the field.

Multilayer Reduced Graphene Oxide Deposited on Carbon Sheet as Electrodes for Supercapacitor Device

Supercapacitor or often referred to as ultracapacitor is well-known for its long-life cycle, rapid charge-discharge cycles, its ability to bridge between battery and conventional capacitor in terms of power density and energy density values [1]. Carbon allotropes like graphene, carbon nanotube, etc. are widely used as electrodes for supercapacitor mainly due to its large porosity and high electrical conductivity. Pure graphene is very difficult to be prepared in large scale, then Reduced Graphene Oxide (rGO) is used as an alternative to graphene with properties similar to graphene. On the previous work [2], it was shown that carbon sheet can act as electrodes for supercapacitor, thus depositing rGO on carbon sheet (C-rGO) as electrode of supercapacitor can be a good choice to increase the capacitance through their high surface area. This research focused on studying the characteristics of symmetric supercapacitor device with C-rGO|C-rGO device configuration in 1M KCl electrolyte system. 0.5 mg/ml GO was deposited on carbon sheet by using UV-Oven Spraying method, creating multilayer rGO with total of 70 layers. The system then measured in Galvanostatic Charge-Discharge with current variations of 1, 2, 3, 4, 5, and 10 mA. Energy storage characteristics of supercapacitor is then to be determined from the obtained measurement results. The measurement showed that the device has energy density of 0.25 Wh/kg to 0.72 Wh/kg and power density of 250 W/kg to 3,000 W/kg. Based on the value of energy density and power density showed that the device made had met requirements as supercapacitor.

Modeling and parameter identification of composite power supply for plug-in HEV

By analyzing the characteristics of the components of PHEV composite power supply, the voltage characteristics, temperature characteristics and capacity efficiency of batteries and supercapacitor are clarified. The dynamic voltage characteristics of batteries and supercapacitor are simulated by modeling the composite power supply. Based on the cross current discharge characteristics of lithium-ion batteries and the application conditions of batteries in PHEV, the second-order linear battery model recommended in PNGV is selected in this paper; for supercapacitor, the simplified RC branch model can be used to describe the characteristics, and the experimental data are used to identify the parameters involved in the model, and the accuracy of the model is verified.

Anomalous diffusion models in frequency-domain characterization of lithium-ion capacitors

Lithium ion capacitors (LICs) have urgent application demands in the field of transportation and renewable energy. In order to better understand the applicable scope and limitations of this kind of energy storage device, frequency-domain testing and modeling are particularly indispensable. In this paper, the frequency-domain characteristics of LICs is analyzed. It is found that the diffusion segment has more obvious non-ideal feature. Two frequency-domain models are proposed to describe the anomalous phenomena in diffusion process. The models realize non-idealized expression by introducing the ordinary diffusion model into fractional differentiation. One of the models is derived from a continuous time random walk scheme with macro constraints, which is introduced for the first time to describe the frequency-domain characteristics of supercapacitors to the best of our knowledge. A matched parameter identification method is presented. The corresponding model parameters can be obtained quickly by combining theoretical calculation and numerical analysis. Finally, the adaptability of the two models are verified through a series of working conditions at different temperatures, voltages and life periods.

A coordinated control strategy based on Photovoltaic-hybrid energy storage system

Photovoltaic power generation is changing day by day, but its system has drawbacks. To compensate for the shortcomings of PV power generation system, the micro-grid system of PV power generation with HES is constructed by using the complementary characteristics of battery and supercapacitor. On the basis of this, we introduce a fuzzy control to realize the fast response of hybrid energy system. A micro-grid model is built based on Matlab/Simulink to verify the feasibility and rationality of the proposed control strategy.

Developing high voltage Zn(TFSI)2/Pyr14TFSI/AN hybrid electrolyte for a carbon-based Zn-ion hybrid capacitor.

Aqueous Zn-ion hybrid capacitors (ZIHCs), integrating the typical characteristics of Zinc ion batteries and supercapacitors, have become a promising candidate to replace or supplement lithium-ion energy storage technology. However, the narrow operating voltage window and the instability of the Zn/electrolyte interface caused by aqueous solvents have become a great challenge for practical applications. Here, we developed a new type of hybrid electrolyte (Zn(TFSI)2/[[Pyr14TFSI]3]16/[AN]4) based on the organic solvent (AN) combined with ionic liquid (Pyr14TFSI) and Zn salt (Zn(TFSI)2). This non-flammable electrolyte benefited from the synergistic advantages of Pyr14TFSI and AN, and could output a wide electrochemical window (3.32 V vs. Zn/Zn2+) and good compatibility with metallic Zn, while possessing excellent wettability. Theoretical and experimental results further reveal that such superb performance originates from the change of Zn coordination environment. Consequently, the constructed ZIHC displays a stable cycling performance (10 000 cycles at 5 A g-1 without significant capacity fade) and a high operating voltage of 2.1 V. This newly developed electrolyte, which solves the conventional interface problem and improves the voltage window, will promote the development of ZIHCs.

Comparative assessment of supercapacitor bank switching techniques under constant resistor, constant current, and constant power loads

High specific power density and longer cycle life features made the supercapacitors as the most prominent option in managing the transient demands of the pulsed power loads. However, the discharging characteristics of supercapacitors confine them from the utilisation of their entire energy. Reflecting on these concerns, this study aims to provide an extensive review of various bank switching circuits of supercapacitors to enhance their energy utilisation. Also, a comprehensive analysis of these switching circuits in terms of power delivery duration, SC cell energy utilisation, terminal voltage variations, system efficiency, and total cost is carried out for the constant resistor, constant power, and constant current loads.

Study on the Manufacturing Characteristics of high Capacity Supercapacitor Using Graphene Electrodes

Study on the Manufacturing Characteristics of high Capacity Supercapacitor Using Graphene Electrodes

Synthesis of a Three-Dimensional Interconnected Oxygen-, Boron-, Nitrogen-, and Phosphorus Tetratomic-Doped Porous Carbon Network as Electrode Material for the Construction of a Superior Flexible Supercapacitor.

To construct a high-performance next-generation carbon-based flexible supercapacitor, high porosity, large mass density, and high flexibility are three significant challenging goals. However, one side always affects another. Herein, high-density tetratomic-doped porous composite carbon derived from sustainable biomaterials is achieved via two-step processes of carbonization and acid-washing treatment. The assembled carbon-based electrodes are highly doped with various heteroatoms (B, O, N, and P) for 33.59 atom %, resulting in abundant porosity, high densities, high pseudocapacitive contribution for 84.5%, and superior volumetric capacitive performance. The fabricated flexible electrode exhibits high flexibility, high mass loading (316 mg cm-3), and remarkable tensile strength (44.6 MPa). Generally, the volumetric performance is key and a significant parameter to appraise the electrochemical characteristics of flexible supercapacitors within a limited space. The aqueous symmetric supercapacitor demonstrates a high volumetric energy density and an excellent power density of 2.08 mWh cm-3 and 498.4 mW cm-3, respectively, along with 99.6% capacitance retention after 20 000 cycles, making it competitive to even some pseudocapacitors.

Review And Prospect of Mn3O4‐Based Composite Materials For Supercapacitor Electrodes

AbstractAs an energy storage device, supercapacitor plays an important role in energy strategy. Improving the energy storage characteristics of supercapacitors has been the focus of research. Mn3O4 has been specially studied because of its low cost, good environmental compatibility and large capacitance. In this review, the synthesis and electrochemical properties of Mn3O4‐based electrode materials are summarized and reviewed. In addition, the development and prospect of Mn3O4‐based electrode materials for supercapacitor is discussed.