Electrical Energy Storage Devices Research Articles

Selection of the torque – speed curves for the units of a wear-resistant brake system of high-mobility wheeled vehicles

With the growth of the power-to-weight ratio of the modern high-mobility wheeled vehicles, the capacity of their working brake systems is no longer sufficient for operation at the high speeds owing to high thermal loads of the brakes. In order to increase the average speed of the vehicle during the long-term downslope decelerations, as well as at the intensive use of the wheel brakes it is necessary to use additional devices – exhaust and retarder brakes. This kind of devices include the exhaust brake installed inside the internal combustion engine and the transmission hydro- and electrodynamic brakes (retarder brakes). The use of an electric machine operating in generator mode for storing the braking energy in an electric storage device is also a promising option. The combination of such additional devices is called “a wear-resistant brake system”. The research is focused on the selection of the torque – speed curves of a wear-resistant brake system providing higher average speeds of the wheeled vehicles and lower loads of the working brake system. Selection of the torque – speed curves of the units of a wear-resistant brake system is carried out by the analysis of the wheeled vehicle operation in different driving cycles which are close to its real operation cycles. These cycles are usually generated for a stationary case with the use of a quasi-stationary mathematical model of the vehicle motion. In the model, the vehicle – terrain interaction is described by means of the equations of the vehicle motion including stochastically generated roads. The analysis of the vehicle operation in different driving cycles provides stochastic data on the loads of the wear-resistant brake system as a whole, which allow selecting the torque – speed curves of its units depending on their operational features. The proposed method provides selection of the required torque – speed curves of the wear-resistant brake system units: the internal combustion engine (operating in the brake mode), the electric machine, and the retarder. Selection of the parameters of the electric machine is the first step for the solution of the next important problem – selection of the required capacity of the electric energy storage device. The results of the analysis provide selection of such combination of the characteristics for each unit of the wear-resistant brake system that will ensure the required deceleration of the vehicle.

Optimization of Electrochemical Flow Capacitor (EFC) design via finite element modeling

Abstract The Electrochemical Flow Capacitor (EFC) is the recently introduced electrical energy storage device for large-scale energy applications. Utilization of high surface area of carbon-based electrode suspended in the electrolyte is the key to the electrical energy storage, by forming a double layer of charges at the interface. In this study, the finite element model was used to examine the behavior of the ionic charge distribution and the maximum current density in EFCs. The current density distribution in the flow channels demonstrated significant dependence on the design and the depth of the flow channel, which ranged from 0.5 mm to 5 mm. The underutilization of the active surface area of carbon continuously increases with increasing channel depth. The geometry of flow channels affected the overall current density by strengthening it at the sharp edges between the current collector and the separating membrane. The geometries based on flow channel shape (circular and box) were tested by varying the depth of the flow channels, current collector shape, and their area in contact with the slurry electrodes to study current density distribution in the flow channel. The experiments were performed with circular flow channels (each 5 mm wide) separated by a 150 µm thick ion-conducting membrane; then, the results were used to optimize the model. The slurry was composed of 0.1 M Na2SO4, 3 wt% Carboxymethyl Cellulose (CMC), and activated carbon powder suspended in water. The studies showed that the maximum activity is observed near the current collector boundary, and slurry underutilization is observed as the distance from the edge increases. Simulations results accorded well with experimental data, including the estimation of the stationary-state current that is achieved during the charging of the slurry.

Series hybrid fuel cell/supercapacitor power source

Hybridization systems working with electric generators and energy storage devices lead to optimal technologies for recent power sources. They are becoming more popular due to their advantages such as high efficiency, saved energy and low pollution. There are many types of architecture of hybridization. This article proposes a novel converter structure for a hybrid fuel cell/supercapacitor application that the fuel cell is hybridized with a bank of supercapacitors. Its benefits include high efficiency and maximum use of supercapacitor energy. The mathematical model is developed. The operation and modeling of the converter are presented. Closed-loop controls by using an indirect-sliding mode technique for the inner current loop and the energy control in the outer loop including a disturbance estimator are provided. Finally, simulation and experimental results obtained from the 150 W testbench are given to validate the proposed converter and system. The obtained results have shown that the proposed converter structure offers the right candidate for a hybridization fuel cell/supercapacitor power source.

An ultrafast supercapacitor built by Co3O4 with tertiary hierarchical architecture

The fast charge/discharge ability is very important for electric energy storage devices. Here, Co3O4 electrode with flower-wire-nanoparticle tertiary hierarchical architecture for ultrafast charge/discharge rate supercapacitor is developed via a facile and scalable hydrothermal method and subsequent sintering treatment. The as-prepared Co3O4 electrode exhibits an outstanding rate performance of 95.6% capability at 80 times current density from 0.5 A g−1 to 40 A g−1 and a good cycling stability of 98.5% retention after 2000 charge/discharge cycles at the current density of 2 A g−1. The Co3O4//AC asymmetric supercapacitor reveals an energy density of 16.25 Wh kg−1 at a power density of 7500 W kg−1. These impressive electrochemical behaviors suggest that such Co3O4 tertiary hierarchical architecture holds great promise for high-rate energy storage devices.

Evaluation of the Properties of an Electrolyte Based on Formamide and LiTFSI for Electrochemical Capacitors

The performance of electrical energy storage devices depend on the electrolyte properties. Concentrated electrolytes are promising for high-performance energy storage devices thanks to their inherent safety and low cost. We study here different concentrated solutions composed of LiTFSI as a salt (0.5, 1.0, 3.0, 4.0 and 4.5 M) and formamide as a solvent for electrochemical capacitor applications. These electrolytes exhibit appreciable ionic conductivity (2.3 to 8.2 mS cm−1), are favor of electrochemical properties of activated carbon-based EDLC. Electrochemical results reveal that, compared to usual electrolytes, high concentrated electrolytes exhibit long-term cyclability with significant capacitance up to 2000 cycles at an operating voltage of 2.2 V. Moreover, this study shows that low concentrated electrolytes highly corrode the Al current collector whereas the high concentrated electrolytes suppress the Al current collector corrosion process owing to the lack of free solvent (uncoordinated to a Li+ cation).

Elucidating Hydrothermally Synthesized CNTs-MnO2 Composites through Electrochemical Scrutiny for Wielding Electrodes in Energy Storage

Search of materials with better electrochemical performance is currently one of the key interests around the globe. In this context, the electrochemical characteristics of MnO2/CNTs (manganese dioxide/carbon nanotubes) composites prepared in two simple steps have been reported. X-ray diffraction confirmed the structural purity of the composite contents revealing that the intensity of peaks first decreased and after the addition of more CNTs, the intensity of the peaks started to increase. Scanning electron microscope was utilized to examine the surface morphology of MnO2/CNTs composites which indicated that with increase of CNTs contents, the granular size of MnO2 particles slightly decreased. The conductivity was inspected by electrochemical impedance spectroscopy, which demonstrated that increase in CNTs concentration provided conducting channels for charge transportation. The energy density calculations revealed that maximum energy density was observed for the composition with 0.5% CNTs. These characteristics inferred that the composite material could be utilized as an electrode in electric batteries and energy storage devices.

Methods for producing an easily assembled zinc-air battery

Zinc-air batteries are considered as the promising alternative to conventional power sources and have received revived research efforts recently due to their high energy density, good safety, environmental friendliness, and potential for low material costs. The design and production of zinc-air batteries is critical to accelerate the commercialization for extending the application range. Herein, we proposed a method for producing plate-type primary zinc-air batteries which apply zinc foil as an example. The proposed method includes the design of an easily assembled zinc-air battery configuration, the preparation of air cathodes and assembly of zinc-air battery. In addition, the galvanostatic discharge performance of the assembled non-flow primary zinc-air battery was tested at a current density of 10 mA cm–2. The method can be applied for the production of commercial zinc-air batteries for laboratory research and industrial manufacture for electric vehicles, consumer electronics, and energy storage devices.•The preparation method for components of zinc-air battery configuration and air cathodes was developed.•The assembly of the zinc-air battery was proposed.•Direct evaluation of discharge performance of the zinc-air batteries produced by the method.

Влияние режимов работы гибридных энергетических комплексов на основе возобновляемых источников энергии на определение типа аккумуляторов энергии

The aim of the work is to study the performance characteristics of generating units operating on the basis of renewable energy sources (RES) as part of a hybrid energy complex and to determine the requirements posed by these generating units to the storage systems in terms of stored energy amounts and power absorption and delivering conditions on long, medium and short intervals of time. Using the data from a real consumer located on Popov Island, the relevant energy complexes were modeled, and their operating modes were calculated and analyzed. The technical requirements posed by the RES-based installations to the performance characteristics of energy storage devices in terms of stored energy amounts and power absorption and delivering conditions on different time intervals are determined. The obtained results are important for elaborating efficient energy storage systems for RES-based hybrid energy complexes for improving their reliability and technical and economic efficiency. It has been established, based on the calculations and analysis of the RES-based hybrid energy complex operation modes, that for meeting the hybrid energy complex requirements, the complex should be fitted with a hybrid energy storage system combining various sources of electrical energy. Some of them, in view of their high energy capacity (e.g., hydrogen electric energy storage devices), can be considered as energy sources for seasonal and daily regulation, and others (supercapacitors) can be regarded as power sources to be used in the modes of absorbing and delivering power pulses on second time intervals.

ОГЛЯД ТА ОБҐРУНТУВАННЯ ВИБОРУ НАКОПИЧУВАЧІВ ЕЛЕКТРОЕНЕРГІЇ ДЛЯ РОБОТИ ЕЛЕКТРОЕНЕРГЕТИЧНИХ ОБ’ЄКТІВ

Urgency of the research.The study of electricity storage for the operation of power facilities, characteristics and their consideration when choosing the type of storage for the facility will optimize the system as a whole.Target setting.Scientific and technical development and the environmental situation make more stringent requirements for the power system.Actual scientific researches and issues analysis.The classification and main characteristics of existing energy storage devices, their main advantages and disadvantages are considered.Uninvestigated parts of general matters defining. ThereThe main problem with the use of new types of electricity storage is the lack of their widespread use in the market of electricity facilities.The research objective.The aim of the work is to develop a methodology for determining the optimal type and model of universal electricity storage and analysis of its advantages and disadvantages.The statement of basic materials. The analysis of existing types of electric energy storage devices and their characteristics is carried out. Methods are proposed that are based on a comparison of unit cost, volume capacity, environmental impact and service life. The main differences of each type of electricity storage, their advantages and disadvantages are analyzed.Conclusions.The proposed method is based on a comparison of unit cost, volume capacity, environmental impact and service life. The main differences of each type of electricity storage, their advantages and disadvantages are analyzed. Using the proposed technique, the optimal choice of electricity storage for power facilities is made.

Ragone plots and discharge efficiency-power relations of electric and thermal energy storage devices

Abstract Ragone plots (energy-power relations) and discharge efficiency-power relations are important for characterizing energy storage (ES) devices, as they contain the information on the maximum power and the available energy. In this theoretical study, these two characteristics and the losses per energy are derived in the framework of endoreversible thermodynamics for ideal electric and thermal ES systems with different dependencies of their intensive thermodynamic variables (potentials, temperatures) of the reservoirs on the extensive state variables (electric charge, heat) that quantify their state of charge. While for battery and latent heat storage device, the normalized Ragone plot is equal to the discharge efficiency-power relation, the two characteristics differ for electric capacitor and sensible heat storage device due to their intrinsically limited depth of discharge at constant power. Due to the decrease of the exergy of heat at decreasing temperature, the discharge efficiency of the ideal sensible heat storage device exhibits a local maximum at a finite power value.

Phenazine-Based Covalent Organic Framework Cathode Materials with High Energy and Power Densities.

Redox-active covalent organic frameworks (COFs) are promising materials for energy storage devices because of their high density of redox sites, permanent and controlled porosity, high surface areas, and tunable structures. However, the low electrochemical accessibility of their redox-active sites has limited COF-based devices either to thin films (<250 nm) grown on conductive substrates or to thicker films (1 μm) when a conductive polymer is introduced into the COF pores. Electrical energy storage devices constructed from bulk microcrystalline COF powders, eliminating the need for both thin-film formation and conductive polymer guests, would offer both improved capacity and potentially scalable fabrication processes. Here we report on the synthesis and electrochemical evaluation of a new phenazine-based 2D COF (DAPH-TFP COF), as well as its composite with poly(3,4-ethylenedioxythiophene) (PEDOT). Both the COF and its PEDOT composite were evaluated as powders that were solution-cast onto bulk electrodes serving as current collectors. The unmodified DAPH-TFP COF exhibited excellent electrical access to its redox sites, even without PEDOT functionalization, and outperformed the PEDOT composite of our previously reported anthraquinone-based system. Devices containing DAPH-TFP COF were able to deliver both high-energy and high-power densities, validating the promise of unmodified redox-active COFs that are easily incorporated into electrical energy storage devices.

Development of a kinetic electric energy drive with magnetic compensation

The optimal parameters of a compact kinetic energy storage device are considered, which allow to cover the widest range of consumers of autonomous solar power plants. Estimated consumer market volumes. A comparative characteristic of various types of electrical energy storage devices is carried out. The advantages and disadvantages of each of the existing types of drives are indicated. The cost characteristic of one charge-discharge cycle of electrochemical storage devices is given. The combined use of kinetic and electric energy storage devices in the structure of a hybrid storage device is shown with the aim of optimizing the cost of generating electric energy from alternative sources of electric energy. In this case, the compensation of high-frequency voltage ripples is carried out due to the energy previously stored in the kinetic storage device. Technical problems arising when using kinetic energy storage devices (flywheels) are considered. These include the presence of a gyroscopic effect that does not allow mobile performance of the drive, as well as special requirements for the material from which the flywheel is made. Possible features of the design of flywheel-based drives are considered. The use of magnetic compensation of the centrifugal forces of the flywheel eliminates the use of high-strength and expensive materials.

Polymer Matrix Nanocomposites with 1D Ceramic Nanofillers for Energy Storage Capacitor Applications.

Recent developments in various technologies, such as hybrid electric vehicles and pulsed power systems, have challenged researchers to discover affordable, compact, and super-functioning electric energy storage devices. Among the existing energy storage devices, polymer nanocomposite film capacitors are a preferred choice due to their high power density, fast charge and discharge speed, high operation voltage, and long service lifetime. In the past several years, they have been extensively researched worldwide, with 0D, 1D, and 2D nanofillers being incorporated into various polymer matrixes. However, 1D nanofillers appeared to be the most effective in producing large dipole moments, which leads to a considerably enhanced dielectric permittivity and energy density of the nanocomposite. As such, this Review focuses on recent advances in polymer matrix nanocomposites using various types of 1D nanofillers, i.e., linear, ferroelectric, paraelectric, and relaxor-ferroelectric for energy storage applications. Correspondingly, the latest developments in the nanocomposite dielectrics with highly oriented, surface-coated, and surface-decorated 1D nanofillers are presented. Special attention has been paid to identifying the underlying mechanisms of maximizing dielectric displacement, increasing dielectric breakdown strength, and enhancing the energy density. This Review also presents some suggestions for future research in low-loss, high energy storage devices.

Enhancing Energy Storage Devices with Biomacromolecules in Hybrid Electrodes.

The development of energy storage devices with higher energy and power outputs, and long cycling stability is urgently required in the pursuit of the expanding challenges of electrical energy storage. The utilization of biologically renewable redox compounds holds a great potential in designing sustainable energy storage systems and contributes in reducing the dependence on fossil fuels for energy materials. Quinones are the principal redox centers in natural organic materials and play a key role as charge storage electrode materials because of their abundance, multiple forms and integration into the materials flow through the biosphere. Electrical energy storage devices and systems can be significantly improved by the combination of scalable quinone-based biomaterials with good electronic conductors. This review uses recent examples to show how biopolymers are providing new directions in the development of renewable biohybrid electrodes for energy storage devices.

Photo-deposition of ZnO/Co3O4 core-shell nanorods with p-n junction for efficient oxygen evolution reaction

Co3O4 has attracted extensive interests as a non-noble-metal electrocatalyst of oxygen evolution reaction, which is critical to many electrical energy conversion and storage devices; however, conductivity has impeded further improvement to its catalysis activity. Herein, ZnO/Co3O4 core-shell nanorods are fabricated on Ni foil by a mild photo-deposition method to accelerate charge transfer between Co3O4 and the conductive substrate. The mild prepare method effectively avoids the oxidation of Ni foil and constructs p-n heterojunction between ZnO and Co3O4. Compared with sole Co3O4, the ZnO/Co3O4 core-shell nanorods exhibit larger electrochemical active surface area and smaller charge transfer resistance. Besides, the XPS results reveal that the strong electron interaction on nanointerfaces induces electronic structure modulation, which may bring interfacial charge transfer from Co to Zn, and further cooperate synergistically toward the oxygen generation in alkali solution. Moreover, the electrochemical active surface area of the ZnO/Co3O4 nanorods varies with the photo-deposit time and influences the OER performance. When the photo-deposit time is 4 h, the as-fabricated ZnO/Co3O4 nanorods exhibit excellent electrochemical performance with overpotential of 294 mV at 10 mA cm−2, Tafel slope of 49 mV dec−1, and outstanding stability for oxygen evolution reaction in alkaline medium.

THE FUNCTIONING MODEL OF INTEGRATED ENERGY SUPPLY SYSTEM WITH CO-GENERATION UNITS OPERATION, TAKING INTO ACCOUNT PROSPECTS OF BIOENERGY DEVELOPMENT IN UKRAINE

In conditions of renewable energy sources development and implementation of modern technologies in the energy sector, energy from biomass in the structure of power supply systems is an actual topic. The development of bioenergy is an important part of ensuring the energy security of many countries, as it enables to reduce fossil fuel consumption, dependence on imported energy sources and ensure sustainable local energy supply. The article presents the functioning model of integrated energy supply system (energy hub) with co-generation units operation, taking into account prospects of bioenergy development in Ukraine. This paper studies the optimal operation problem of an energy hub with multiple energy sources to serve electricity and heat loads in the presence prices. The main task was solved to make full use of its own energy sources to meet the needs of consumers in energy carriers with the most effective financial performance. The availability of electric and thermal energy storage devices will allow more efficient usage of available energy resources and equipment. Usage of a cogeneration plant in the structure of the energy hub gives the opportunity to provide energy resources and the possibility of generated electricity trading. A multicriteria approach to the planning and optimization of the operation of such energy hub is proposed. According to the simulation results using the example of an energy hub, it is shown that this method is suitable for planning hourly energy consumption with a compromise in terms of the minimum cost of these energy resources and CO2 emissions.

Method for determining the basic energy characteristics of elements of a hybrid car engine

A method for determining the basic energy characteristics of a hybrid car engine is presented. The technique takes into account parameters of the vehicle and parameters of the driving mode during operation. The basis of the technique is traction power and energy calculation. According to the source data, the flow of energy passing through mechanical, electrical chains and through the storage of electrical energy is determined. The technique is implemented in the form of algorithms for the calculation program and allows one to simultaneously receive the main technical characteristics of the vehicle when it is equipped with a hybrid engine of a sequential, parallel and mixed type. The presented method allows one to obtain the following values: the required power of the internal combustion engine, the required power of the motor generator, the minimum capacity of the electrical energy storage device, the estimated fuel consumption. This article presents an example of calculating the basic parameters of a combined power plant for a car weighing 1500 kg when driving it along the standard European driving test cycle. Similar calculations can also be carried out for any other cycle and parameters of the vehicle, including the bus, truck, and tractor.

Conversion of Biomass Waste into High Performance Supercapacitor Electrodes for Real-Time Supercapacitor Applications

Sustainable conversion of biomass waste into an economic and high performance electrical energy storage device receives excellent scientific and technological interest. The high manufacturing cost ...

Dual‐Graphite Batteries with Flame‐Retardant Electrolyte Solutions

AbstractAlthough trimethyl phosphate (TMP)‐based electrolyte solutions are effective to resist flames in non‐aqueous electrical energy storage devices, they are usually not so compatible with Li‐graphite negative electrodes. Herein, we solve this problem by increasing the concentration of LiPF6 salt in the solution. A benchmark graphite negative electrode (MCMB, mesocarbon microbeads) can deliver a capacity over 325 mAh g−1 and maintain good cyclability in a solution of 3 M LiPF6‐ethyl methyl carbonate (EMC)/TMP (7 : 3 by vol.). Moreover, our previous work has confirmed that the graphite positive electrode also works very well in the above solution. Therefore, this solution can cater to both anion‐graphite and Li‐graphite intercalation electrodes, which enables the construction of dual‐graphite batteries (DGBs). There are some problems arising during the DGB operation, and corresponding strategies are proposed.

Selenium-Carbon Nanotubes Composite Cathode with Long Cycle Life for Rechargeable Li-Se Batteries

In the past two decades, lithium-ion batteries (LIBs) have been extensively utilized in portable electronic devices as well as electric vehicles (EVs). However, conventional LIBs depending on the lithium intercalation reactions of anode and transitional metal oxide cathode materials have limited capacities and low energy densities, which prevent their broader deployment as power sources for prolonged usage. High energy density and durable electrical energy storage devices are the key factors to meet the crucial demands for high-performance portable electronic devices and EVs. Selenium (Se), as a congener of sulfur in the periodic table, has been proposed as an alternative cathode material for rechargeable lithium batteries. Although Se has lower theoretical capacity (678 mAh g-1) than sulfur, it can provide a high volumetric capacity of 3253 mAh cm-3 because of its high mass density (4.8 g cm-3). In addition, selenium has a much higher electronic conductivity (1×10-3 S m-1), which implies that Se could provide better electrochemical activity. However, Se cathode is still facing similar challenges as sulfur such as poor cycling life and low Coulombic efficiency, which are attributed to the dissolution and shuttle effect of the formed high-order polyselenides as redox intermediates in the ether-based electrolyte. In addition, the significant volume change increases the difficulty for Li-Se batteries to be used in practical applications. During the last decade, lots of effort have been put into developing approaches to address these problems, thereby increasing energy density and cycle life of Li-Se batteries. In this contribution, we synthesized Se nanowires in the presence of carbon nanotubes (CNTs) by a facile method. The experimental process for preparing the Se/CNT composite consists of dissolving selenium oxide (SeO2) and beta-cyclodextrin (β-cyclodextrin) and dispersing the CNT bundles in an ethanolic mixture with de-ionized water. The vigorously stirring and ultrasonication procedure in the initial mixture cause fine dispersion of CNTs. In addition, the ethanol extenuates the hydrophobic activity of CNTs, and hence accelerates the dispersion-weave process by ultrasonication. The addition of ascorbic acid solution ensures the product of selenium nanowires. Upon another ultrasonication for selenium nanowires and CNTs to be perfectly woven, and then filtered and dried, the Se/CNT composite electrode was obtained. The filter paper has a diameter of 7 cm, which decides the overall size of the composite electrode. Se nanowires are weaved with CNTs to form a uniform binder-free composite electrode, which has superior electrical conductivity. This synthesis method provides a path for fabricating the Se cathodes with controllable mass loadings and thicknesses. At initial state, Se is in the form of branched nanowires with a diameter of <150 nm and length of 1-2 µm, interweaving with CNTs. By studying the composites electrodes with different mass loadings of active materials and different thicknesses, it is found that the electrode thickness has influence on the accumulation of redox products upon repeated cycling. The structural and morphological changes are analyzed by scanning electron microscope (SEM). Finally, the electrochemical phenomena are revealed experimentally, and enhanced cycling performance is achieved. The composite electrode with 23 µm thickness and 60% Se loading shows a high initial capacity of 537 mAh g-1, followed by stable cycling performance with a capacity of 401 mAh g-1 after 500 cycles at 1C rate. This study reports a synthesis strategy to obtain Se/CNT composite cathode with long cycle life for rechargeable Li-Se batteries. Figure 1