Power Supercapacitors Research Articles

ZnO doped SnO2 nano flower decorated on graphene oxide/polypyrrole nanotubes for symmetric supercapacitor applications

Due to their high power density, lengthy cyclability, quick charge-discharge rates, and environmentally friendly design, supercapacitors are incredibly effective electrochemical energy storage devices. A lot of work has been progressed in this direction to increase the specific power and cyclic stability of supercapacitor mainly by using various metal oxides with 2D composites and high concentration electrolytes. But, there are some challenging issues like low energy density, high production cost, and short cyclic life. In this work, we aimed to resolve the low energy density and operating voltage of electrodes by selecting multiphase inorganic-organic material with a suitable concentration of electrolyte. To create such supercapacitor electrodes for high energy storage applications, ZnO doped SnO2 nanoflower decorated on graphene oxide/polypyrrole nanocomposite, which are novel materials with large specific surface area and cyclic stability were studied.The electrochemical study of the nanocomposite materials is done by studying the cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance (EIS) techniques. The supercapacitor device fabrication is processed using ZS/GP2 electrode, and the analysis of supercapacitor performance is also studied. As a result, ZS/GP2 nanocomposite showed a good capacitive behavior with a maximum specific capacitance of 392 F g−1 at 75 mV s−1 scan rate with significantly high specific energy and power density of 31.6 Wh kg−1 and 5177 W kg−1, respectively after the 27,000 consecutive charge-discharge (GCD) cycles at the current density of 0.25 A g−1. The results evidence that these hybrid materials are highly promising electrode materials for energy storage applications.

Fabrication of NiMn2O4 nanospheres and its hybrid with polyaniline for high energy and high power supercapacitor with long cycle stability

NiMn2O4 nanospheres have been prepared by a solution combustion method and hybridised with polyanilne by the dilute polymerization method. The metal oxide and its polymer hybrid forms were characterized by several physicochemical methods and microscopic techniques. The capacitive nature and cyclic stability were studied by cyclic voltammetry and galvanostatic charge–discharge measurements. The newly fabricated NiMn2O4 nanospheres and PANI-NiMn2O4 nanohybrid showed high specific capacitance values of 374 Fg−1 and 442 Fg−1 respectively, at the scan rate of 10 mVs−1. The NiMn2O4 nanospheres showed enhanced energy density (13.8 WhKg−1) compared to its hybrid form (2.82 WhKg−1). However, the power density of the PANI-NiMn2O4 nanohybrid (565.2 Wkg−1) was found to be higher than that of the pure NiMn2O4 nanospheres (447.18 WKg−1). In addition to that, both the electrode materials showed the same columbic efficiency (∼96 %) after 1000 consecutive cycles.

The Challenge of Digital Transition in Engineering. A Solution Made from a European Collaborative Network of Remote Laboratories Based on Renewable Energies Technology

Society currently faces two crucial challenges: digital transition and energy transition. Educative innovation plays a key role in this challenging scenario, particularly engineering careers, where laboratory practices are as important as theoretical classes. This paper presents a standardized training platform supported by five European universities which include a remote laboratory experience. Each university is responsible for developing a training module under the guidance provided by the responsible entity (University of Huelva, Spain). For this purpose, the University of Huelva has implemented a remote laboratory based on a supercapacitor power bank. The rest of the universities have selected any other renewable source and have replicated the information and communications technology (ICT) infrastructure. The result is a European network materialized on a homogenized platform where teachers and students can find all the teaching materials (theory and practice) to train and to be trained in renewable energy matters in the new digital era.

Design and experiment of a novel stepwise preheating system for battery packs coupled with non-dissipative balancing function based on supercapacitors

Lithium-ion batteries have advantages such as low self-discharge rates, high energy density, and environmental benefits. They are widely used in electric vehicles. However, their further application is limited by the inconsistency between batteries after assembly and the reduced battery performance in low-temperature environments. This article proposes a novel stepwise preheating system for battery packs that integrates a non-dissipative balancing function based on supercapacitors. The supercapacitor acts as an energy transfer and storage medium for balancing the power battery pack and heating the preheating battery pack. The preheating battery pack serves as an energy supplier for heating the power battery pack and as an energy storage unit during the balancing process of the power battery pack. This article studies the influence of low-temperature environments on the discharge capacity of power batteries and supercapacitors, explores the impact of environmental temperature on the relationship between state of charge (SOC) and open-circuit voltage (OCV), and the SOC0-OCV relationship of batteries, and clarifies the relationship between temperature and SOC0 required to meet the maximum pulse discharge test. It develops a parameter matching method for a supercapacitor and a preheating battery pack that meets the preheating requirements of power battery pack. It designs the topology structure of a balancing system based on supercapacitors with the flying capacitor method. It uses the battery terminal voltage as a balancing variable and formulates a non-dissipative balancing control strategy under static conditions. Results show that the low-temperature preheating system can warm up the preheating battery pack from −25 °C to 0 °C within 7 min, raise the temperature of the power battery pack from −25 °C to 0 °C within 27 min, and further increase the temperature of the power battery pack to 8 °C, achieving its maximum pulse discharge test in low SOC0 (33.5 %) state. During the non-dissipative balancing process, the energy transfer in the battery prioritizes charging the preheating battery pack, the average balancing current is about 8 A, and the energy utilization rate is about 80 %. This study provides a new approach for coupling the preheating technology and the power battery pack balancing technology in low-temperature environments.

EXPERIMENTAL ANALYSIS OF HYBRID ENERGY STORAGE SYSTEM BASED ON NONLINEAR CONTROL STRATEGY

In this paper, a nonlinear integral sliding mode control for a hybrid energy storage system (HESS) based stand-alone dc microgrid has been proposed and applied experimentally. This hybrid system comprises a PV, super-capacitor, and battery. A classical PI-based linear control strategy has been designed to control battery and super-capacitor systems based on decoupling the high and low-frequency components to estimate reference current. Since the frequent discharge during operation, super-capacitor power can reach the lowest value, affecting controller performance and making the system unstable. From the experimental result, a nonlinear Integral sliding mode control ISMC is performed as an inner loop controller to regulate battery and super-capacitor power. Also, the PI controller is implemented as an outer loop controller to regulate the dc-link. The proposed control approach is compared with the linear PI controller to improve life extension and minimize stress on the battery. As a result, the proposed control strategy has achieved high dynamic system performance.

Battery state of charge based improved adaptive droop control for power management of a microgrid having large scale renewable generation

Power management in a standalone microgrid having large scale renewable generation is generally based upon droop control strategies. However, the renewable sources such as photovoltaics (PV), which are interfaced with microgrid through power electronic converters have low inertia. Because of low inertia, the transient power variation during switching events like change in load may be very large and may result into variation in voltage and frequency beyond permissible limits. In this paper an adaptive scheme for power management of a standalone microgrid is proposed, which is based on available state of charge (SoC) of the batteries to mitigate these issues. The proposed battery SoC based adaptive droop control for power management allows smooth transition of distributed energy resources (DERs) from maximum power point tracking (MPPT) mode to adaptive droop mode and vice versa. The transient behaviour is handled with the help of batteries and supercapacitor (SC), which is further improved with the help of fuzzy logic based proportional integral controller (FLC-PI). A significant drop in SC power during switching events is obtained with FLC-PI. The test microgrid is composed of multiple PV generation at different locations as primary source of generation, multiple batteries energy storage system (ESS) at different locations, fuel cell (FC), supercapacitor (SC) and a dynamic load.

Економічний аналіз технологій акумулювання електричної енергії

The use of cost-effective large-scale electrical energy storage systems is necessary for the reliability of the power system due to the rapid growth of its production by powerful renewable energy sources. The article examines stationary electric energy storage devices, namely: sodium-sulfur; lead-acid; lithium-ion; nickel-cadmium; vanadium reduction, polysulfide-bromine and zinc-bromine flow batteries; supercapacitors; superconducting magnetic energy. Information from open sources on technologies of electric energy storage has been analyzed. As a criterion of optimality in world practice, the weighted average cost of electric energy for the life cycle is used, which ensures the self-sufficiency of the source of its production or accumulation for the entire cycle of its existence. A comparison of modern technical and economic indicators of various electrical energy storage technologies is made. Calculated average cost of electrical energy storage over the life cycle (LCOS) of various storage devices. It was determined that supercapacitors and superconductors of magnetic energy have the lowest cost of storage, and lithium-ion ones have the highest. Therefore, to minimize short-term power fluctuations in power systems, superconducting magnetic and supercapacitor storage devices are preferable. They have a lower cost of electric energy storage, short response time and high specific power.

Experimental validation of a novel power smoothing method for on-grid photovoltaic systems using supercapacitors

Renewable energy sources have been widely developed in grid-connected systems. However, a challenge to overcome is the random characteristic of renewable resources such as solar irradiance, photovoltaic power fluctuations caused by cloud movement could cause instability of the utility grid. To solve this drawback, several authors have proposed various power smoothing methods for photovoltaic systems using supercapacitors. Nevertheless, sizing optimization and operability of the supercapacitor has not been properly studied. Forecasting power fluctuations is an important strategy to avoid the unnecessary operation of the supercapacitor in certain cases. In this paper, a novel power smoothing method (predictor – corrector) using supercapacitors for a grid-connected photovoltaic system is proposed, the method consists of two stages, prediction and correction. The main novelty of the new method is the use a simple k-means algorithm application model in the cycle estimation stage for supercapacitors, with the aim of selecting representative data of power fluctuations and supercapacitor charge/discharge cycles. Then, for the correction stage, the novel proposed method uses ramp rate algorithms to generate the reference signal to control the state of charge of the supercapacitor.The validation of the new proposed method has been done through exhaustive laboratory experiments under different cloudiness events. The results show that the energy losses when applying the new method are lower with respect to the moving average and ramp rate methods. Furthermore, the number of technical violations is reduced, demonstrating the feasibility of the proposed method to ensure successful mitigation of PV power fluctuations.

Optimal Energy Management for Hydrogen Economy in a Hybrid Electric Vehicle

Fuel cell hybrid electric vehicles (FCEVs) are mainly electrified by the fuel cell (FC) system. As a supplementary power source, a battery or supercapacitor (SC) is employed (besides the FC) to enhance the power response due to the slow dynamics of the FC. Indeed, the performance of the hybrid power system mainly depends on the required power distribution manner among the sources, which is managed by the energy management strategy (EMS). This paper considers an FCEV based on the proton exchange membrane FC (PEMFC)/battery/SC. The energy management strategy is designed to ensure optimum power distribution between the sources considering hydrogen consumption. Its main objective is to meet the electric motor’s required power with economic hydrogen consumption and better electrical efficiency. The proposed EMS combines the external energy maximization strategy (EEMS) and the bald eagle search algorithm (BES). Simulation tests for the Extra-Urban Driving Cycle (EUDC) and New European Driving Cycle (NEDC) profiles were performed. The test is supposed to be performed in typical conditions t = 25 °C on a flat road without no wind effect. In addition, this strategy was compared with the state machine control strategy, classic PI, and equivalent consumption minimization strategy. In terms of optimization, the proposed approach was compared with the original EEMS, particle swarm optimization (PSO)-based EEMS, and equilibrium optimizer (EO)-based EEMS. The results confirm the ability of the proposed strategy to reduce fuel consumption and enhance system efficiency. This strategy provides 26.36% for NEDC and 11.35% for EUDC fuel-saving and efficiency enhancement by 6.74% for NEDC and 36.19% for EUDC.

Robust State Machine Passivity-based Control Applied to Fuel Cell Hybrid Source

The disadvantages of fuel cell systems, such as their high cost, lack of reactivity, and inability to collect energy when the fuel cell vehicle is braking, can be overcome by hybridization with storage devices such the battery or the supercapacitors, which is capable of doing so. The energy management system is regarded as an important technique for the hybrid system. Its primary function is to autonomously identify the appropriate quantity of energy that will be supplied by the hybrid source to meet the demand in terms of the load's energy requirements. The primary purpose in this work is the design and validation of an energy management technique based on the state machine and the passivity-based control to manage and control the energy flow of a hybrid fuel cell vehicle's power source, with a fuel cell system serving as the primary source of power and batteries and supercapacitors serving as the secondary sources of power. The results of MATLAB simulations show that the proposed strategy works as expected and the control system has robust dynamic features. Consequently, the passivity-based control makes possible to globally control the hybrid system which has been presented by a state space model in order to reach a set of stable equilibria. Whereas, the state machine is efficient in terms of performance, easy to implement, and provides ideal balance between the amount of energy that is generated and the amount that is consumed.

Structural Elucidation of Nitrogen-Doped Reduced Graphene Oxide/Hausmannite Manganese Oxide Nanocomposite for Supercapacitor Applications

The increasing consumption of fossils fuel accompanied by related carbon emissions and complex set of issues associated with the generation and use of electricity has raised an urgent need for reliable, renewable and sustainable energy alternatives [1]. Nanotechnology and the production of nanostructured materials has driven the rapid growth in the research of carbon nanomaterials as energy storage materials for supercapacitor (SCs) applications. Among several carbon nanomaterials explored for SCs, graphene has shown to be the leading carbon nanomaterial, due to its intriguing properties such as highly tunable surface area, outstanding electrical conductivity, good chemical stability and excellent mechanical behavior [2]. Due to challenges in the bulk synthesis of graphene, reduced graphene oxide (rGO) has been opted as the preferred choice for the development of SC devices. Transition metal oxides also gained much interest in various research industries as materials for SCs applications. Among transition metal oxides, manganese oxide, MnxOy, appeared to be the promising electrode material due to its interesting properties such as cost effectiveness, high theoretical specific capacitance, high theoretical surface area (≥ 1370 m2 g-1), and excellent electrochemical reversibility. However, the poor conductivity of manganese oxide restricts its progress in SC applications [2, 3]. Therefore, great attention has been devoted to the improvement of the electronic properties of manganese oxides-based electrode materials by decorating them on highly conductive carbon-based nanomaterials. Although intensive study has been done on carbon nanomaterials integrated with MnxOy for pseudocapacitors, there is still less literature on the use of Mn3O4 nanoparticles decorated on carbon materials for application in SCsThis work presents a hydrothermal synthesis of the nitrogen-doped reduced graphene oxide/hausmannite manganese oxide (N-rGO/Mn3O4) nanohybrid which showed a great electrochemical performance such as high specific capacitance of 345 F g-1 and a maximum of specific energy of 12.0 Wh kg-1 (current density: 0.1 A g−1), and a maximum specific power of 22.5 kW kg-1 (current density: 10.0 A g−1) in a symmetric configuration. The nanohybrid further showed excellent supercapacitor performance in an asymmetric configuration, with the maximum specific energy and power reaching 34.6 Wh kg−1 (0.1 A g−1) and 14.01 kW kg−1 (10.0 A g−1) respectively. The results obtained affirm the use of N-rGO/Mn3O4 as a potential electrode material for high energy and power supercapacitor devices that can be commercially competitive to that of rechargeable batteries.

Design of semi-actively controlled battery-supercapacitor hybrid energy storage system

For vehicle propulsion, electric vehicles (EVs) utilize lithium ion (Li-ion) based battery storage system. Electric powertrain provides high Efficiency, but Li-ion cells liable to degradation with increase in temperature and load. While a larger energy storage system (ESS) produces more power, but it also increases the ESS's cost, volume, and size. A hybrid energy storage system (HESS) based on batteries and supercapacitor can be utilized to minimize total ESS size and improve performance during heavy loading conditions, with the supercapacitor provide power during charging/discharging peak power. Battery and supercapacitor are connected together with the help of a DC-DC Converter. HESS is a single-unit battery and supercapacitor that combines the benefits of high battery energy density and high supercapacitor power density. Whereas Sizing of HESS is a challenging task because of adding supercapacitor it increases overall size and cost of ESS, to address this issue in this study particle swarm optimization (PSO) is used to optimize HESS size and increase battery cycle life (BCL). The MATLAB/SIMULINK environment is used to model both the Battery Energy Storage System (BESS) and the Hybrid Energy Storage System (HESS). Optimized results are used to compare battery cycle life of BESS and HESS. The optimization findings under the Urban Dynamometer Driving Schedule (UDDS) are compared to the battery-only ESS results, which show a 8.927 percent increase in battery cycle life.

Large-Signal Stabilization Method for Islanded DC Microgrids Considering Battery and Supercapacitor Hybrid Energy Storage Systems

Islanded DC microgrids composed of distributed generators (DGs), constant power loads (CPLs), parallel converters, batteries and supercapacitors (SCs) are typical nonlinear systems, and guaranteeing large-signal stability is a key issue. In this paper, the nonlinear model of a DC microgrid with a hybrid energy storage system (HESS) is established, and large-signal stability criteria are obtained. The HESS consists of batteries and SCs. The derived criteria reveal the influences of the filter parameters, CPL power, DG power and the proportional control parameters of the battery converter and the SC converter on the system large-signal stability. Furthermore, important large-signal stabilization methods for regulating the HESS converter’s control parameters can easily achieve the large-signal stabilization of islanded DC microgrids without extra equipment. The paper is summarized as follows: First, the topology of and control strategy for a DC microgrid with an HESS and CPLs are proposed. Then, according to the characteristics of the HESS, the DGs and the CPLs, the system is equivalently simplified. Finally, the nonlinear model and large-signal stability criteria are both derived using the mixed potential theory, and a large-signal stabilization design method for the HESS converter’s control parameters is proposed. The experimental and simulation results show the effectiveness of the proposed large-signal stabilization method.

Tuning cationic transport in Nisalen polymers via pseudo-crown functionality

Polymeric films based on nickel complexes with salen-type ligands have received considerable attention recently owing to electrocatalytic, electrochromic, and charge storing properties. The latter makes them suitable metal-organic materials for electrochemical power sources, i.e., batteries and supercapacitors. Optimization of the properties of electrode materials is closely linked to the understanding of charge storage mechanisms. The introduction of CH3O substituent into the molecule results in peculiar ionic transport mechanism, owing to the possibility of alkaline ions coordination. Here we study the recharging mechanism of poly[Ni(CH3Osalen)] films in various electrolyte solutions. In presence of alkali ions, the electronic effects of methoxy substituent provide mixed anionic and cationic charge compensation mechanism, as cations reversibly coordinate to the present pseudo-crown functionality. By applying the combination of XRD, CV/EQCM and EIS methods to the film in electrolytes containing Li+, Na+, K+, and Et4N+ cations, and BF4−, ClO4− and bistrifluoromethanesulfonimidate (TFSI−) anions, we propose a model that describes the ionic transport in such polymeric films and allows to estimate the anionic and cationic contribution to the total amount of transferred species during charging and discharging.

A triboelectric driven rectification free self-charging supercapacitor for smart IoT applications

The combination of energy harvester and energy storage in a single unit without an external complex circuit has sparked significant interest, owing to the potential for converting and storing energy in a single integrated device. Herein, a self-charging supercapacitor power cell (SPC) is proposed in which the energy generated from the triboelectric nanogenerator (TENG) is stored in a supercapacitor without power management or rectifier circuits via a ‘tribo-electrochemical mechanism.’ The SPC comprises poly (vinylidene fluoride-co-hexafluoropropylene) P(vdf-HFP) as a polymer separator, impregnated with ionic liquid electrolyte, and metal-organic framework derived cobalt nanoporous carbon/laser-induced graphene/copper (Co-NPC/LIG/Cu) electrode. Owing to the large surface area of SPC electrodes, an areal capacitance of 25.60 mF cm-2, the energy density of 0.0278 mW.h cm-2, and the power density of 0.089 mW/cm-2 are achieved. Furthermore, the self-charging SPC combines TENG and SPC into a single integrated device, with TENG generating 2.5 mW power, which can successfully charge the SPC to a maximum voltage of 210 mV within 9 s. Finally, the dynamic and static signals from the SPC device are utilized to control the ‘jump’ and ‘duck’ actions of T-REX in the gaming interface, and different SPC charge levels are utilized as a smart switch for turning on the smart home appliances. Thus, this study reveals the potential for charging the supercapacitor via TENG without any external circuit and provides significant insights into understanding the energy conversion process in self-charging supercapacitors.

Regenerative Braking Control Strategy with Real-Time Wavelet Transform for Composite Energy Buses

In order to meet the safety requirements of automobile braking, to improve the braking energy recovery rate of pure electric buses and increase their driving range, the maximum regenerative braking force that the motor can provide is used to determine the front and rear wheel friction braking force distribution curve. A parallel regenerative braking control strategy, A, is proposed to make full use of the motor performance. Aiming at the problems of low power density and short cycle life with a single power battery, a composite energy system composed of power batteries and supercapacitors is designed, and an alternative energy control strategy, D, using real-time wavelet transform control is proposed. The required power is decomposed into high-frequency components and low-frequency components by using the wavelet transform control, in which the high-frequency power is borne by the supercapacitor to avoid impact on the power battery. The simulation model was created using MATLAB/Simulink software, and the simulation was carried out under combined cycle conditions to verify the effectiveness of the control strategy. The simulation results showed that compared with the original vehicle control strategy, adopting the A regenerative braking control strategy can reduce the battery SOC drop by 5.15%, increase the relative increase by 47.9%, and improve the braking energy recovery rate. Compared with the traditional logic threshold regenerative braking control strategy, AC, the AD control strategy can effectively reduce the impact of the peak current and high-frequency demands of the power battery on the battery. The maximum output current of the battery was reduced by 39.5%. The decrease in battery SOC decreased by 0.69%, and the relative increase increased by 12.43%. The driving range and braking performance of the vehicle have thus been effectively improved.

Operando Tracking of Ionic and Electronic Percolation in Electrodes for Energy Storage Application Using AC-in Plane Impedance

Achieving efficient electronic and ionic electrode percolation is one of the most important parameters to improve batteries and supercapacitors power performance. Various electrical and electrochemical techniques (Cyclic voltammetry, Electrochemical Impedance Spectroscopy, EQCM, SECM, in-situ XRD, etc) can be used to assess the electronic and ionic transport properties in these electrodes. However, there are only few studies and techniques on tracking the change in resistance of an electrode during electrochemical polarization [1, 2, 3], which plays a key-role on its electrochemical performance.In this study, we propose a new method to achieve operando resistance measurement under alternative current (AC), that we’ll call in-plane impedance measurement, under bias potential. In these experiments, the electrodes are deposited onto an insulating substrate so that, differently from conventional electrochemical impedance spectroscopy experiments, here the electrode in-plane conductivity is measured. Moreover, this method allows for distinguishing the ionic part of the in-plane electrode impedance from the electronic part that appears at high and low frequencies, respectively.In this work, in-plane electronic and ionic transport properties of porous carbon (YP50F) and MXene (Ti3C2) electrode are studied while being fully charged or. During polarization, both the ionic and electronic percolation change with the applied potential for both electrode, that could be associated with electrode volume and conductivity change under potential and/or because of some doping caused by ionic specific electrosorption. This operando in-plane impedance measurement method furthers the fundamental understanding of ionic and electronic transport properties and may turn out to be effective tool to improve the electrochemical performances of capacitive, pseudocapacitive, or battery-like electrodes.

Monolithic integration of MoS2 quantum sheets on solid electrolyte for self-charging supercapacitor power cell governed by piezo-ionic effect

Piezoelectric-driven self-charging supercapacitor power cells (SCSPCs) emerged as promising energy devices that can simultaneously harvest-, convert-, and store electrical energy in an integrated cell. Recent research efforts have been focused on (i) understanding the fundamental mechanism of the energy transduction process and (ii) improving the self-charging performances, respectively. Herein, we utilized the piezo-ionic properties of Nafion (solid polyelectrolyte) together with their bi-functional properties (separator cum electrolyte) in a SCSPC (using MoS2 quantum sheets as energy storage electrodes) and examined their self-charging performance. The experiments on the evaluation of piezo-ionic properties of the Nafion polyelectrolyte showed that they can produce a peak-peak voltage of 910 mV due to the generation of Donnan potential. Next, studies on the electrochemical performance of solid state MoS2-Nafion-MoS2 SCSPC revealed that they possess a high capacity/capacitance (0.40 μAh cm−2/1.81 mF cm−2), energy density (252 μJ cm−2), and long-cycle life. Finally, studies on the self-charging characteristics of the MoS2-Nafion-MoS2 SCSPC show that they can self-charge upto 243 mV with superior electro-mechanical stability. Collectively, the piezo-ionic mediated energy transfer process in the self-charging process of the MoS2-Nafion-MoS2 SCSPC is explained in accordance with the Nernst theory for a two-dimensional system. This work opens-up a fresh paradigm towards the development of all-solid-state SCSPCs utilizing solid electrolytes.

Recent trends, challenges, and perspectives in piezoelectric‐driven self‐chargeable electrochemical supercapacitors

AbstractThe increasing demand for wearable electronic devices has resulted in tremendous progress in research on energy harvesting and storage devices/technologies. Energy storage devices require a power source to charge them, whereas energy harvesting devices require a storage compartment to store the harvested energy for sustainable delivery. Recently, a piezoelectrically driven self‐charging supercapacitor power cell (SCSPC) was developed to harvest and store electrical energy in a solitary system to determine the potential impact of these two types of energy devices for wearable electronic applications. This review describes the recent advances in piezoelectric‐driven SCSPCs in terms of device configuration, piezoelectric separator, electrolyte types, electrode materials, current collectors, and system integration. This review focuses specifically on the principles and mechanism of the self‐charging process that occurred in the SCSPCs and the use of a promising piezo electrochemical spectroscopic tool to realize the piezo electrochemical energy transfer and storage process in the SCSPCs. Further, the current challenges and new perspectives for future developments in the emerging area of SCSPCs or integrated energy devices are discussed.

Facile hydrothermal synthesis of high-performance binary silver-cobalt-sulfide for supercapattery devices

The rapid depletion of fossil fuel resources, along with rising energy consumption, has prompted the development of renewable energy storage systems. More focus must be placed on renewable and sustainable energy sources in order to reduce the reliance on fossil fuels for energy production. Because of their tremendous energy and great power density, batteries and supercapacitors are being intensively researched in renewable energy storage systems. In this work. We used a one-step simple hydrothermal approach to synthesize silver sulfide, cobalt sulfide, and their binary compound silver cobalt sulfide with a 50/50 weight ratio. X-ray diffraction (XRD) and scanning electron microscopy (SEM) examined the materials' crystallinity and surface morphology. Electrochemical behavior of silver sulfide AgS (S1) cobalt sulfide CoS (S2), and silver cobalt sulfide (AgCoS) was investigated in the three-electrode assembly. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) have been carried out to explore its electrochemical characteristics. The electrochemical analysis reveals that silver sulfide AgS (S1) provides a specific of 402 C/g at 3 mV/s while cobalt sulfide CoS (S2) provides the specific capacity of 289C/g at 3 mV/s. when combined silver sulfide and cobalt sulfide in a 50/50 weight ratio specific capacity achieved with silver cobalt sulfide AgCoS (S3) is 701.01C/g at a low scan rate of 3 mV/s. An asymmetric device (AgCoS//AC) was developed by employing activated carbon as the negative electrode and the best silver cobalt sulfide as the positive electrode. This asymmetric supercapacitor has been investigated through CV, GCD, and stability tests for 1000 consecutive cycles. The device delivered a high energy density of 22.34 Wh/kg in parallel to the high power density of 899.2 W/kg. After 1000 consecutive cycles, the columbic efficiency of this device increases to 105% while maintaining capacity retention of 82%. This study indicates that silver cobalt can be an efficient electrode material for supercapattery devices.