Electrical Energy Storage Research Articles

The ultra-high electric breakdown strength and superior energy storage properties of (Bi0.2Na0.2K0.2La0.2Sr0.2)TiO3 high-entropy ferroelectric thin films

The electric breakdown strength (Eb) is an important factor that determines the practical applications of dielectric materials in electrical energy storage and electronics. However, there is a tradeoff between Eb and the dielectric constant in the dielectrics, and Eb is typically lower than 10 MV/cm. In this work, ferroelectric thin film (Bi0.2Na0.2K0.2La0.2Sr0.2)TiO3 with a dielectric constant of 115 is found to exhibit an ultra-high Eb = 10.99 MV/cm, attributing to the high-entropy effects that could result in dense nanostructures with refined grains, low concentration of oxygen vacancies, low leakage current and small polar nano-regions in the thin film. A recoverable energy storage density of 5.88 J/cm3 with an excellent energy storage efficiency of 93% are obtained for the dielectric capacitor containing the thin-film dielectrics. Remarkably, the dielectric capacitor possesses a theoretical energy storage density of 615 J/cm3 compatible to those of electrochemical supercapacitors. The high-entropy ferroelectric thin films with ultra-high Eb and superior energy storage properties are much promising dielectrics used in next-generation energy storage devices and power electronics.

Overcurrent Limitation in Hydrogen Storage Power Plants (HSPP)

The importance of electrical energy storage (EES) systems has been increasingly recognized for enabling the large-scale integration of intermittent renewable energy sources (RES) into the power grid. Among these systems, the Hydrogen Storage Power Plant (HSPP) stands out as a solution capable of independently managing the supply and storage of electrical energy based on network requirements. Previous investigations have shown that the HSPP operating in grid forming mode (GFM) can provide the required ancillary services in the form of instantaneous, primary and secondary control reserves similar to conventional fossil-fired power plants. However, unlike these traditional synchronous generators, the HSPP consists of power semiconductor devices, resulting in much lower overcurrent tolerance. This paper addresses this challenge by proposing a simple yet robust control technique that regulates the maximum current across the HSPP grid interfacing inverter functioning in GFM. The results demonstrate that the controller can maintain the maximum current magnitude below a threshold of 1.2 pu while ensuring the required reactive current contribution during a three-phase fault.

Electrical-energy storage into chemical-energy carriers by combining or integrating electrochemistry and biology

Our societies must reconsider current industrial practices and find carbon-neutral alternatives to avoid the detrimental environmental effects that come with the release of greenhouse gases from fossil-energy carriers.

General definition of hydrogen energy and related electrochemical technologies

Electrochemical energy conversion, based on the transformation between electrical energy and chemical energy, is crucial for the storage and utilization of renewable electrical energy, as well as the eco-friendly production of valuable fuels and chemicals. Here we put forward a general definition of hydrogen energy that covers the energy storage/release in any hydrogen-involved chemical bonds, such as H–H, C–H, and N–H bonds. Given that H2 gas, hydrocarbons, and hydronitrogens are not only high-energy-density fuels but also important industrial feedstock s, the successful implementation of efficient energy storage/release in the H–H (hydrogen cycle), C–H (carbon cycle), and N–H (nitrogen cycle) bonds are of great significance in establishing sustainable energy systems and reducing dependence on fossil fuels, which contributes to address global energy crisis and environmental problems. We provide a concise overview of the current development status of some key low-temperature (< 100 °C) electrochemical technologies relevant to general hydrogen energy, including fuel cells, water electrolysis, CO2 electrolysis, and N2 electrolysis. This discussion aims to elucidate the major challenges and future trends in this field.

From stress to charge: investigating the piezoelectric response of solvate ionic liquid in structural energy storage composites.

Solvate ionic liquids (SILs) are a class of ionic liquids where the liquid-state salt is chelated by a coordinating solvent, and of interest due to their advantageous properties such as low vapour pressure and superb thermal and chemical stability for energy storage applications. The electromechanical and piezoelectric effect were studied in lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solvated by triethylene glycol dimethyl ether (triglyme, G3), forming [Li-G3]TFSI. These effects were also investigated in full solid polymer electrolyte (SPE) used in energy storage devices, consisting of [Li-G3]TFSI paired with an epoxy-based resin system. The SIL's electromechanical response was first established in isolation, as well as within the SPE. Experimental data demonstrates the effect of a major part of the SPE contributing to the electrical potential generation during application of force and subsequent pressurisation as well as depressurisation, underlined by a direct piezoelectric effect. SPE response to applied load is explored after the recent discovery of liquid-to-crystalline phase transition following pressurisation in pure ionic liquids. This finding has the potential to ameliorate the performance of energy storage composites via additional effects of charging such a device by subjecting it to stress, leading to increased efficiency. Results to date show a bulk potential difference across the SIL of up to 150 mV, while the SPE potential response is scaled down due to a significantly lower volume of SIL at the interface (∼30 mV). Nevertheless, such findings can still significantly affect the performance of carbon fibre (CF)-based structural supercapacitors and batteries that are able to store and release electrical energy whilst simultaneously contributing to load-bearing performance.

Performance and Cost Comparison of Drive Technologies for a Linear Electric Machine Gravity Energy Storage System

Performance and Cost Comparison of Drive Technologies for a Linear Electric Machine Gravity Energy Storage System

MOF/graphene oxide based composites in smart supercapacitors: a comprehensive review on the electrochemical evaluation and material development for advanced energy storage devices.

The surge in interest surrounding energy storage solutions, driven by the demand for electric vehicles and the global energy crisis, has spotlighted the effectiveness of carbon-based supercapacitors in meeting high-power requirements. Concurrently, metal-organic frameworks (MOFs) have gained attention as a template for their integration with graphene oxide (GO) in composite materials which have emerged as a promising avenue for developing high-power supercapacitors, elevating smart supercapacitor efficiency, cyclic stability, and durability, providing crucial insights for overcoming contemporary energy storage obstacles. The identified combination leverages the strengths of both materials, showcasing significant potential for advancing energy storage technologies in a sustainable and efficient manner. In this research, an in-depth review has been presented, in which properties, rationale and integration of MOF/GO composites have been critically examined. Various fabrication techniques have been thoroughly analyzed, emphasizing the specific attributes of MOFs, such as high surface area and modifiable porosity, in tandem with the conductive and stabilizing features of graphene oxide. Electrochemical characterizations and physicochemical mechanisms underlying MOF/GO composites have been examined, emphasizing their synergistic interaction, leading to superior electrical conductivity, mechanical robustness, and energy storage capacity. The article concludes by identifying future research directions, emphasizing sustainable production, material optimization, and integration strategies to address the persistent challenges in the field of energy storage. In essence, this research article aims to offer a concise and insightful resource for researchers engaged in overcoming the pressing energy storage issues of our time through the exploration of MOF/GO composites in smart supercapacitors.

Optimal Sizing and Energy Management of Electric Vehicle Hybrid Energy Storage Systems With Multi-Objective Optimization Criterion

Optimal Sizing and Energy Management of Electric Vehicle Hybrid Energy Storage Systems With Multi-Objective Optimization Criterion

Recycling of metals from LiFePO4 battery cathode material by using ionic liquid based-aqueous biphasic systems.

Lithium-ion batteries are essential for electric vehicles and energy storage devices. With the increasing demand for their production and the concomitant surge in waste generation, the need for an efficient and environmentally friendly recycling process has become imperative. This work presents a new approach for recycling of metals from the LiFePO4 (LFP) cathode material. The cathode material was first leached by a HCl solution without an oxidizing agent. Subsequently, an ionic-liquid-based aqueous biphasic system (IL-based ABS) was used for the separation of lithium and iron from leachate solutions, followed by a precipitation process. The influence of the acid concentration, solid-to-liquid ratio and leaching time on the leaching yield was investigated. UV-vis absorption spectra revealed the presence of mixed-valent iron in the leachate, with 83 ± 1% Fe(ii) and 17 ± 1% Fe(iii). The ABS systems comprised tributyltetradecylphosphonium chloride [P44414]Cl and a salting-out agent (HCl or NaCl). The extraction percentage of iron reached 90% and less than 1% of lithium was extracted under the studied optimal conditions. Further enhancement of iron extraction, reaching 98%, was achieved via a two-stage cross-current extraction process. Iron was precipitated from the loaded IL phase with an efficiency of 97% as Fe(OH)2 and Fe(OH)3, using an aqueous ammonia solution. Lithium was precipitated as Li3PO4 with a lithium purity of 99.5% by adding K3PO4 solution. The ionic liquid used in the process was efficiently regenerated and used in four extraction cycles with no activity decline, with an extraction percentage of 90% of iron in each cycle.

New pyrochlore La2Zr2O7 ceramics with ultra-high breakdown electric field strength and energy storage efficiency

The application potential of the La2Zr2O7 ceramic as a lead-free dielectric capacitor was first proposed and investigated. The breakdown field strength is 1350 kV cm−1, the energy storage density is 3.89 J cm−3, and the efficiency is 89.78%.

Utilisation of electric vehicles and battery energy storage systems for the enhancement of PV hosting capacity in a distribution network

To foster decarbonisation of the transportation sector, there is a growing widespread global adoption of electric vehicles (EVs) as a clean, environmentally friendly alternative to fossil-fuel-dependent internal combustion engine vehicles (ICEV). This has required the electrical power system to distribute power to EV charging stations. In addition, battery energy storage systems (BESSs) have also been deployed to improve network resilience. Both EVs and BESSs on distribution networks (DNs) may be charged using photovoltaic (PV) resources. Subsequently, huge numbers of PV plants have been installed globally over the past decade. With excessive PV penetration into the distribution network (DN), the consequences are risks of operational constraint violations such as over-voltages, feeder line congestion, protection maloperation and high harmonics. This requires limiting the amount of installed PV to alleviate these risks. The maximum amount of PV which can be integrated into the DN without violating these network operational limits is the PV hosting capacity (PVHC). This paper proposes models for quantifying the impacts of EVs and BESSs on the PV hosting capacity of DNs using the stochastic particle swarm and gradient descent algorithm (PSO-GD). The simulation results of case studies have shown that the proposed method is accurate, fast, and efficient.

Application of sulfur-based composite materials in the positive electrode of lithium-sulfur batteries

Traditional lithium-ion batteries are no longer able to keep up with the growing need for energy storage efficiency in areas like electric cars and renewable energy storage. Because of their great energy density, affordability, and environmental friendliness, lithium-sulfur batteries are regarded as a very promising solution for secondary battery systems. Sulfur-based compounds are an essential part of lithium-sulfur batteries and have a direct impact on the battery’s energy density and performance. However, sulfur-based compounds are easily soluble in electrolytes and have low conductivity, which shortens battery cycle life and energy efficiency. Sulfur dissolution can be successfully inhibited and capacitance may be enhanced by optimizing the structure and characteristics of sulfur-based materials, which will improve the overall performance of lithium-sulfur batteries. To enhance the performance of lithium-sulfur batteries, this article suggests three modification techniques for sulfur-based materials. These techniques mostly include compounding sulfur with carbon compounds, metal oxides, and polymers. This article also outlines the shortcomings of the present lithium-sulfur battery research and looks forward to the future development direction.

Energy Management in Hybrid Electric and Hybrid Energy Storage System Vehicles: A Fuzzy Logic Controller Review

Energy Management in Hybrid Electric and Hybrid Energy Storage System Vehicles: A Fuzzy Logic Controller Review

A polarization double-enhancement strategy to achieve super low energy consumption with ultra-high energy storage capacity in BCZT-based relaxor ferroelectrics.

Due to dielectric capacitors' already-obtained fast charge-discharge speed, research has been focused on improving their Wrec. Increasing the polarization and enhancing the voltage endurance are efficient ways to reach higher Wrec, however simultaneous modification still seems a paradox. For example, in the ferroelectric-to-relaxor ferroelectric (FE-to-RFE) phase transition strategy, which has been widely used in the latest decade, electric breakdown strength (Eb) and energy storage efficiency (η) always increase, while at the same time, the maximum polarization (Pmax) inevitably decreases. The solution to this problem can be obtained from another degree of freedom, like defect engineering. By incorporating Bi(Zn2/3Ta1/3)O3 (BZT) into the Ba0.15Ca0.85Zr0.1Ti0.9O3 (BCZT) lattice to form (1 - x)Ba0.15Ca0.85Zr0.1Ti0.9O3-xBi(Zn2/3Ta1/3)O3 (BCZT-xBZT) solid-solution ceramics, in this work, ultrahigh ferroelectric polarization was achieved in BCZT-0.15BZT, which is caused by the polarization double-enhancement, comprising the contribution of interfacial and dipole polarization. In addition, due to the electron compensation, a Schottky contact formed at the interface between the electrode and the ceramic, which in the meantime, enhanced its Eb. A Wrec of 8.03 J cm-3, which is the highest among the BCZT-based ceramics reported so far, with an extremely low energy consumption, was finally achieved. BCZT-0.15BZT also has relatively good polarization fatigue after long-term use, good energy storage frequency stability and thermal stability, as well as excellent discharge properties.

Constructing asymmetric gradient structures to enhance the energy storage performance of PEI-based composite dielectrics.

Enhancing the high electric field resistance and energy storage capacity of polymer dielectrics has been a long-standing challenge for the iterations of power equipment. Synergistic inhibition of carrier injection and transport is vital to energy storage performance improvement. Herein, promising polymer polyetherimide (PEI) was employed as a matrix and wider bandgap boron nitride nanosheets (BNNSs) were used as a reinforcing filler. Utilizing high-throughput stochastic breakdown simulations with the distribution characteristics of BNNSs as parameters, a series of topological gradient structures with the potential to enhance performance were obtained, thereby shortening the experimental cycle. Changing the BNNS distribution of symmetric/asymmetric and positive/inverse gradients, as well as the total and gradient contents of BNNSs, means that the position and condition of the surface barrier layer and central hinder layer change, which influences the energy storage performance of the polymer at room temperature and high temperature. Remarkably, the asymmetric gradient structure composite dielectrics exhibited excellent performances. Among them, the PEI-based composite dielectric with 2 vol% BNNS asymmetric inverse gradient distribution (gradient content of 1 vol%) achieved energy densities of 8.26 and 4.78 J cm-3 at room temperature and 150 °C, respectively. The asymmetric gradient structure design strategy holds great promise for optimizing the energy storage capacity of polymer dielectric capacitors.

Partial Power Converter for Electric Vehicle Hybrid Energy Storage System Using a Controlled Current Source Cascade Architecture

Partial Power Converter for Electric Vehicle Hybrid Energy Storage System Using a Controlled Current Source Cascade Architecture

One-step fabrication of high energy storage polymer films with a wide bandgap and high melting temperature induced by the fluorine effect for high temperature capacitor applications with ultra-high efficiency.

The development of polymer dielectrics with both high energy density and low energy loss is a formidable challenge in the area of high-temperature dielectric energy storage. To address this challenge, a class of polymers (Parylene F) are designed by alternating fluorinated aromatic rings and vinyl groups in the polymer chain to confine the conjugating sequence and broaden the bandgap with the fluorine effect. The target films with desired thickness, ultra-high purity, and a wide bandgap are facilely fabricated by a one-step chemical vapor deposition (CVD) technique from monomers. The symmetric and bulky aromatic structures exhibit high crystalline performance and excellent stability at high temperature. The presence of strongly electronegative fluorine atoms effectively enhances bandgap and electron trapping capability, which effectively reduces the conduction loss as well as the possibility of breakdown at high temperatures. CVD technology avoids the post-processing film-forming process, ensuring the fabrication of thin films with high quality. These benefits allow Parylene F films to effectively store electrical energy at temperature up to 150 °C, exhibiting a record discharged energy density of 2.92 J cm-3 at charge-discharge efficiency exceeding 90%. This work provides a new idea for the design and synthesis of all-organic polymer dielectric films for high temperature applications.

An active learning approach to model solid-electrolyte interphase formation in Li-ion batteries

Li-ion batteries store electrical energy by electrochemically reducing Li ions from a liquid electrolyte in a graphitic electrode.

Sustainable hydrothermal carbon for advanced electrochemical energy storage

The development of advanced electrochemical energy storage devices (EESDs) is of great necessity because these devices can efficiently store electrical energy for diverse applications, including lightweight electric vehicles/aerospace equipment.

Utilization of Coal Fly-Ash derived Silicon (Si) as Capacity Enhancer of Li-Ion Batteries Anode Material

The increasing demand for energy has caused a rise in coal usage, resulting in high fly ash generation. The high SiO2, Al2O3, and Fe2O3 content in fly ashes (FAs) allow them to be processed in electrical energy storage technology, such as lithium-ion-based secondary batteries. The research aims to develop silicon from FAs for Li-ion battery applications. The fabrication of silicon materials employed in this study are (i) extraction of SiO2 from FA, (ii) gelation of SiO2, (iii) magnesiothermic reduction of SiO2 to Si under N2 flow, (iv) purification of silicon, (v) the solid-state composite fabrication of Si/C. The as-prepared Si was characterized. XRD test showed the presence of silicon phase and minor impurities in Mg. SEM analysis of the Si showed that the material has a polymorph shape with a rough surface of micron-sized secondary particles. EDX test showed the presence of impurities in the form of O and Mg atoms; meanwhile, the EDX mapping confirmed the dominant distribution of Si in the sample. Galvanostatic charge-discharge analysis of a battery with 5%Si/C anode and LiNi0.8Co0.1Mn0.1O2 or NCM811 cathode resulted in a specific charge and discharge capacity of 600 mAh/g and 473.6 mAh/g, respectively, which is greater than the graphite theoretical capacity of 372 mAh/g.