Characterization Of Supercapacitors Research Articles

State of charge estimator based on tractable extended state observers for supercapacitor packs

A state of charge estimator (SOCE) is proposed for a single and a supercapacitor pack aimed at easy implementation and low computational cost extended state observers. This SOCE reduces modeling errors by implementing extended states using the classic supercapacitor equation. The proposed method involves a simple characterization of supercapacitors, which are tested using different discharge currents up to 40 [A] and subjected to added measurement noise. The proposed estimator is compared against different performance indexes, including the Unscented Kalman filter (UKF), unscented Kalman filter with parameter adaptation (PA), Extended Kalman Filter (EKF), Kalman filter with open-circuit voltage (OCV), Particle Filter (PF), and H-infinity estimator. This comparison was conducted using discharge profiles under different experimental conditions, where the SOCE herein proposed leads to the lowest error among all documented indexes and a performance improvement between 5.53 [%] and 99.90 [%]. Similarly, SOCE facilitates the characterization of the model inputs, reducing the preprocessing time while improving the execution time by 37 [%], and its estimation error by up to 86.77 [%]. These features enable the robust online implementation of embedded systems, improving SOC estimation.

Experimental Characterization of Hybrid Supercapacitor Under Different Operating Conditions Using EIS Measurements

Experimental Characterization of Hybrid Supercapacitor Under Different Operating Conditions Using EIS Measurements

Graphite Paper-based Device for Energy Storage Application

The demand for versatile flexible energy storage device has arisen due to their potential, application in wearable and portable electronic product. This study presents the characterization of graphite paper-based capacitor and supercapacitor that are produced utilising commercially available pencils to draw a design by developing cheap, green, and reliable low profile electrical electrodes. The objectives of this study are to design graphite paper-based electrodes for energy storage application, characterize the physical properties of the electrodes and electrical properties of the device. Material characterization have been performed including morphology analysis of the electrodes using field emission scanning electron microscope (FESEM), compositional structures by using Energy dispersive X-ray spectroscopy (EDX) and chemical properties of the graphitic electrodes using Raman spectroscopy. Next, the electrical performance of the pencil drawn capacitor and supercapacitor have been performed. It is found that the Acidic G/PANI-Paper supercapacitor sample shows the best electrical performance in terms of lowest resistance with 0.59 MΩ, 1.12 MΩ, 1.8 MΩ and highest capacitance with 27.5 μF, 38.1 μF, 55.25 μF for respective 6 cm2, 8 cm2 and 10 cm2 area size. These characteristics show that the graphite-paper based device has a great potential in flexible energy storage applications.

Characterization of Supercapacitors for Electric Vehicles Applications

Characterization of Supercapacitors for Electric Vehicles Applications

Preparation and characterization of hydrogen storage medium (IMO/TPAC) and asymmetric supercapacitor (IMO/TPAC‖TPAC) using imogolite (IMO) and biomass derived activated carbon from tangerine peel (TPAC) for renewable energy storage applications

The blooming of renewable energy technology is magnificent in order to overcome the shrinking availability of fossil fuels and global warming. Hydrogen is considered the most prominent clean and green energy carrier. Hence, the present work focuses on the preparation and characterization of imogolite (IMO) clay and highly porous-natured activated carbon derived from the Tangerine Peel (TPAC) nanocomposite. SEM exhibits the IMO/TPAC nanocomposite reveals the presence of IMO embedded at the surface of TPAC. From the BET studies, there is a profound enhancement for the specific surface area of IMO/TPAC nanocomposite (1323 m2 g−1) compared to pristine TPAC (902 m2 g −1) and IMO (217 m2 g −1). A 6.3 wt% hydrogen storage capacity was achieved at 70 °C and the same (6.3 wt%) amount of hydrogen desorption was noticed at 108 °C for the IMO/TPAC nanocomposite. The electrochemical hydrogen storage of the IMO/TPAC electrode exhibits a hydrogen discharge capacity of 2573 mAh/g at 41st cycle with excellent columbic efficiency of 92.4%, capacitance retention of 86.2% and superior corrosion resistance of 20.3 mA/cm2. The fabricated ASC exhibits a maximum specific capacitance of 183 F g−1 and retains capacitance of 85.1% for 5000 cycles. The as-fabricated ASC has an excellent energy density of 125 Wh kg−1 and power density of 2634 Wkg−1 at a wide operating potential window of 2.1 V. This ASC could able to power blue and white LEDs. Hence, these excellent characteristics proved that the prepared nanocomposite may serve as an excellent energy storage material.

Supercapacitor auto analyser: An automated data analysis software for supercapacitor characterization

High-performance supercapacitors (SCs) with high power, energy, and long-life cycles, are essential for innovating wearable and portable electronics as extensively reported in literature. The Web of Science shows more than 23,000 papers published since 2018 with the topic ‘Supercapacitor’, number that keep growing, from 732 papers per year in 2012 to an average of 4651 papers per year since 2018. However, the establishment of performance metrics on the reported values should be achieved to reduce inconsistencies in their real performances. For that reason, we developed the Supercapacitors Auto Analyser (SCAA) program for SCs data analysis to support the community to establish performance metrics for SC devices, with standard terms, equations, and units. The SCAA generates important graphs with the SCs key properties and electrochemical performance such as capacitance, energy, power, coulombic efficiency (CE), equivalent series resistance (ESR), drop potential (Vdrop), cycling stability, and time constant. These results are calculated from common data generated by potentiostat on SCs characterization such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). With appropriate inputs, the SCAA provides as many as 50 graphs with accurate normalizations by mass, area, or volume in a few minutes. This automation of data analysis is packed in a software made available to the community in the supplementary materials and website www.scaasoftware.com.

Fabrication and characterization of supercapacitor comprising mango kernel derived electrode under different electrolyte system

AbstractIn this work, supercapacitor or ultra‐capacitor cells are composed of active carbon material (ACM) having BET specific surface area of 1133 m2 g−1. The ACM is prepared by carbonizing waste biomass (mango kernel) at 900°C. To develop high porosity in ACM, potassium hydroxide was used as an activating agent. Porous morphology of the synthesized ACM is explored through Scanning Electron Microcopy. Thereafter, two supercapacitor cells have been composed by using the mentioned ACM (electrode material) and KOH 6 M & NaOH 1 M (electrolytes). Applicability of the electrode material for supercapacitor has been tested electrochemically through the standard CV, EIS, and CD techniques. Observed capacitive assets from CV curve at 5 mV s−1was 151.5 F g−1(with KOH 6 M) and 133 F g−1(with NaOH 1 M). Experimentally obtained impedance data from EIS technique were compared and fitted theoretically by utilizing Randles fitting circuit. By taking frequency into consideration, it is found that the KOH 6 M based cell is providing lower time constant value and supporting better diffusion process than NaOH. Analysis of CD curve at 1.1 A g−1have given the capacitance of 136.5 F g−1and corresponding energy and power density of 12.1 Wh kg−1and 930 W kg−1. In addition to this, the small voltage drop and low ohmic resistance observed with KOH based system suggests its better capacitive assets than NaOH based supercapacitor system. Moreover, good capacitance retention of 85% is observed in a 2000 life cycle test.

Hydrotrope-assisted interconnected mesoporous polyindole-decorated carbon nanotubes: synthesis, characterisation, and fabrication of asymmetric supercapacitor

Present work reports on the hydrotrope (TOAB) assisted facile polymerization of indole in presence of CNT with interconnected mesoporous morphology and their enhanced electrochemical performance.

Nanocellulose-Based Flexible Electrodes for Safe and Sustainable Energy Storage

The intensive use of battery-powered electronic devices, in addition to the challenging recycling requirements, have contributed to the accumulation of e-waste, one of the most alarming environmental issues of the modern world. This urges the importance of developing advanced energy storage systems by using non-toxic and more sustainable materials1. Nanocellulose as the most abundant bio-polymer, can tackle current ecological and safety concerns but also keep up with contemporary resilience requisites in powering flexible electronics. Herein, we present the development of organic nanocellulose-based battery electrodes, that can be used in applications with relatively low energy storage demands, such as medical systems, wearables and bendable Internet of Things (IoT) devices. We investigate hybrid electrodes composed of nanocellulose fibres and carbon-based battery active materials, by implementing a safer, aqueous fabrication processing and with a focus on understanding the underlying charge storage mechanisms2. The main constituent of the electrodes is a porous nanocellulose network that maintains structural integrity acting as a binder but also transports ions from an organic electrolyte to the active battery material with reduced diffusion limitations. The overall battery structure is flexible and mechanically robust, minimizing any volume changes during charge/discharge, which translates to cycling stability3.The nanocellulose-based electrodes were manufactured by using different techniques including vacuum filtration and blade coating, and yielded free-standing and current-collector-integrated electrodes. Structural properties and surface morphology were examined via atomic force microscopy (tapping mode and conductive-AFM), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), while electrochemical atomic force microscopy (EC-AFM) was used for in operando visualization and elucidation of molecular level charge transfer mechanisms occurring at the electrode-electrolyte interface. Electrochemical performance was assessed by variable-rate cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP). Furthermore, bending stress tests were conducted where the bending radius and charge/discharge profile of the electrode are correlated. The proposed battery concept paves the way for safe, non-toxic, mechanically flexible and sustainable energy storage technologies that aim to fulfil the growing need for low-power commercial devices. References Leung, O. M., Schoetz, T., Prodromakis, T. & Ponce de Leon, C. Review—Progress in Electrolytes for Rechargeable Aluminium Batteries. Journal of The Electrochemical Society 168, 056509 (2021).Schoetz, T., Gordon, L., Ivanov, S., Bund, A., Mandler, D. & Messinger, R. Disentangling faradaic, pseudocapacitive, and capacitive charge storage: A tutorial for the characterization of batteries, supercapacitors, and hybrid systems. Electrochimica Acta 412, 140072 (2022).Kim, J.-H., Lee, D., Lee, Y.-H., Chen, W. & Lee, S.-Y. Nanocellulose for Energy Storage Systems: Beyond the Limits of Synthetic Materials. Advanced Materials 31, 1804826 (2019).

A review on characterization of supercapacitors and its efficiency analysis for different charging methods and applications

AbstractThe dependence on renewable energy to solve the major energy issues related to global warming and shortage of energy resources is increasing drastically. This has led to high level awareness of proper energy storage and management. In this regard, supercapacitors have evolved as an efficient energy storage solution and hence successfully employed in several applications. This is attributed to its high‐power density, superior performance, and extended maintenance‐free lifetime. Also, it is known for low equivalent series resistance, that means, only a small amount of energy is lost while its charging/discharging even at high current. As a result, it has developed a lot of inquisitiveness among the research community of recent past for further exploration of different aspects of supercapacitors, ranging from material science, modeling and characterizations, engineering applications, and so forth. This review article aims at putting forth an exclusive study of their characterization of supercapacitor for different charging methods and applications. Further, the prime focus is given to the efficiency estimation of supercapacitors which is very essential as it denotes the amount of energy loss or the utilizable state of charge. The analysis has been carried out based on different charging methods and applications, which is essential for improving overall system reliability and performance. The purpose is to organize all important research carried out in this domain till date and to stimulate further insights for effective energy storage and management.

Realization and characterization of flexible supercapacitors based on doped graphene electrodes

Realization and characterization of flexible supercapacitors based on doped graphene electrodes

Electrochemical activation of commercial graphite sheets for supercapacitive applications

Carbon-based substrates are widely used as current collectors for high-performance energy storage materials in supercapacitors. However, these substrates exhibit negligible charge storage due to inferior electrochemical activity and small surface area. Herein, electrochemical activation is utilized to enhance the electrochemical activity of – inherently inactive – commercial graphite sheets for supercapacitive applications. The results reveal that the electrochemically activated graphite sheets render a 30-fold increase in areal capacitance, i.e., from 22 to 447 mF cm−2, which can be ascribed to the activation of graphite oxide functional groups on the surface. Also, the influence of electrochemical activation time on electrochemical performance is explored in detail, followed by the fabrication and characterization of symmetric supercapacitors based on the optimum process parameters in single-cell and tandem configurations, demonstrating the potential of electrochemically activated graphite sheets in practical applications.

Highly efficient and biodegradable flexible supercapacitors fabricated with electrodes of coconut-fiber/graphene nanoplates

We report the fabrication and electrochemical characterization of biodegradable and flexible supercapacitors (SCs). The conductive electrodes of these SCs were pieces of compacted coconut fibers coated by graphene nanoplates. An oral electrolyte solution (OES) and rice paper were used as electrolyte and separator, respectively. The SCs’ encapsulation was made of gelatin/pectin. According to the electrochemical tests, the maximum capacitance and specific energy of the cell made with the biodegradable components were 670.8 F g−1 and 134.2 Wh kg−1, respectively. After adding MgTiO3 nanoparticles (NPs) to the anode, both, the capacitance and specific energy were enhanced by ≈37% and by ≈20%, respectively. For comparison purposes, the OES electrolyte was substituted by a conventional acidic electrolyte (PVA/H3PO4) in the SCs, but the capacitance and specific energy obtained were lower (175.9 F g−1 and 35.2 Wh kg−1). Interestingly, the biodegradable cells exhibited very long discharge times of 550–600 min and a stable output voltage in the range of 0.54–0.71 V, which has not been observed previously for biodegradable SCs. The SCs made with MgTiO3 NPs stored charge by redox reactions and the redox centers were oxygen vacancies (defects), Mg2+/Mg0 and Ti3+/Ti4 (the presence of such centers was confirmed by x-ray photoelectron spectroscopy, Raman and absorbance measurements). In general, we demonstrated that the biodegradable SCs are sustainable/eco-friendly energy sources that are promising to substitute the conventional technologies of Li or alkaline batteries made with toxic/corrosive components that contaminate the environment.

Characterization and Modeling of Supercapacitors Used for Hybrid Electric Energy Storage

Characterization and Modeling of Supercapacitors Used for Hybrid Electric Energy Storage

Revisiting the Time-Domain and Frequency-Domain Definitions of Capacitance

The capacitance is a characteristic function of an electrical energy storage device that relates the applied voltage on the device to the accumulated electric charge. It is inconsistently taken in some studies as a multiplicative function in the time domain [i.e., q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> (t)=c <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> (t) ×v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> (t)], and in others as a multiplicative function in the frequency domain [i.e., Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s)=C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s) × V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s) derived from the definition of admittance I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s)/V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s) = s C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s)], despite the fact that the capacitance is time- and frequency-dependent. However, the convolution theorem states that multiplication of functions in the time domain is equivalent to a convolution operation in the frequency domain, and vice versa. In this work, we revisit and compare the two outlined definitions of capacitance for an ideal capacitor and for a lossy fractional-order capacitor. Although c <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> (t) = C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> (s) = C for an ideal constant capacitor, we show that this is not the case for fractional-order capacitors which exhibit frequency-dispersed impedance, memory effects, and nonexponential relaxation functions. This fact is crucial in the accurate modeling and characterization of supercapacitors and batteries. For these devices, and for being consistent with measurements using conventional impedance analyzers, it is recommended to apply the integral convolution definition in the time domain which reverts to the multiplicative definition in the frequency domain.

On the inverse relaxation approach to supercapacitors characterization

[Display omitted] A novel inverse relaxation technique for supercapacitor characterization is developed, modeled numerically, and experimentally tested on a number of commercial supercapacitors. It consists in shorting a supercapacitor for a short time τ, then switching to the open circuit regime and measuring an initial rebound and long-time relaxation. The results obtained are: the ratio of “easy” and “hard” to access capacitance and the dependence C(τ), that determines what the capacitance the system responds at time-scale τ; it can be viewed as an alternative to used by some manufacturers approach to characterize a supercapacitor by fixed capacitance and time-scale dependent internal resistance. Among the advantages of proposed technique is that it does not require a source of fixed current, what simplifies the setup and allows a high discharge current regime. The approach can be used as a replacement of low-frequency impedance measurements and the ones of IEC 62391 type, it can be effectively applied to characterization of supercapacitors and other relaxation type systems with porous internal structure. The technique can be completely automated by a microcontroller to measure, analyze, and output the results.

A rational experimental approach to identify correctly the working voltage window of aqueous-based supercapacitors

It is common to find in the literature different values for the working voltage window (WVW) range for aqueous-based supercapacitors. In many cases, even with the best intentions of the widening the operating voltage window, the measured current using the cyclic voltammetry (CV) technique includes a significant contribution from the irreversible Faradaic reactions involved in the water-splitting process, masked by fast scan rates. Sometimes even using low scan rates is hard to determine precisely the correct WVW of the aqueous-based electrochemical capacitor. In this sense, we discuss here the best practices to determine the WVW for capacitive current in an absence of water splitting using complementary techniques such as CV, chronoamperometry (CA), and the electrochemical impedance spectroscopy (EIS). To accomplish this end, we prepare and present a model system composed of multiwalled carbon nanotubes buckypaper electrodes housed in the symmetric coin cell and soaked with an aqueous-based electrolyte. The system electrochemical characteristics are carefully evaluated during the progressive enlargement of the cell voltage window. The presence of residual Faradaic current is verified in the transients from the CA study, as well as the impedance changes revealed by EIS as a function of the applied voltage, is discussed. We verify that an apparent voltage window of 2.0 V determined using the CV technique is drastically decreased to 1.2 V after a close inspection of the CA findings used to discriminate the presence of a parasitic Faradaic process. Some orientations are presented to instigate the establishment in the literature of some good scientific practices concerned with the reliable characterization of supercapacitors.

Synthesis and characterization of Zn doped CdS nanoparticles as electrode material for supercapacitor application

The pure and Zn doped CdS nanoparticles were synthesized using a simple method of co-precipitation. The structural, functional group and morphological analysis were carried through XRD, FTIR and SEM analysis. For supercapacitor applications, cyclic voltammetry analysis was studied for pure and Zn doped CdS nanostructures. From the XRD analysis all the samples were formed as a hexagonal crystal structure. SEM images show that the prepared Zn doped CdS formed like form as the flaks. The supercapacitor characterization (CV analysis) suggest that CdS and CdS-Zn electrodes are exhibit pseudocapacitive nature and it delivered the specific capacitance of 302 and 277 Fg−1 at a scan rate of 10 mV s−1.

Printing of graphene supercapacitors with enhanced capacitances induced by a leavening agent

The excellent electrical and mechanical properties of graphene make it a promising electrode material for energy storage devices such as supercapacitors. However, graphene flakes tend to restack upon processing which lowers the inner electrode surface area that contacts the electrolyte. We report on a straightforward and scalable approach where we add a chemical leavening agent to suppress the restacking of printed and reduced graphene oxide (rGO) flakes, resulting in a significant enhancement of the electrode capacitance. Upon mild heating, the leavening agent releases gasses that rise the gaps between rGO flakes and, hence, increase the surface area that is accessible for the electrolyte. We also optimize ink and micro-dispensing process that is utilized to print such risen rGO electrodes. The supercapacitor characterization indicates that the capacitance enhancement strongly depends on the size of the GO flakes; sizes on the order of magnitude of microns are most suitable. The printed and risen rGO electrodes feature typical electrical double layer capacitance behavior along with a good cycling stability having an 82% capacitance retention after 5000 charge-discharge cycles at a current density of 1.0 A/g.

Supercapacitor Characterization Using Universal Adaptive Stabilization and Optimization

This paper presents a simplified supercapacitor model and a universal adaptive stabilization, optimization (UAS+O) based parameter identification technique. Analytic solutions for the description of supercapacitors current, voltage, subject to cyclic voltage and current sources of varying amplitudes and frequency, consistent with electric vehicle driving cycles, are developed. Supercapacitor I-V relationships show hysteresis, indicating simultaneous energy storage and dissipation mechanisms. A reduced equivalent circuit model is proposed to accurately represent hysteresis I-V characteristics. The proposed UAS+O based technique for estimating model parameters, is supported by mathematical proofs, simulation, and experimental results.