Theoretical Energy Storage Density Research Articles

Enhancing energy storage performance of dielectric capacitors: Tailoring CaO-SrO-Na2O-Nb2O5-SiO2 glass-ceramics through controlled crystallization for pulse power applications

As potential dielectric materials for capacitors, glass-ceramics exhibit significant promise in the realm of pulse power supply. Extensive research has been undertaken to explore the commendable voltage resistance and favorable dielectric properties of glass-ceramics. They exhibit a rapid charge and discharge rate. However, the limited energy storage density of glass-ceramics constrains their practical application. In this study, we focused on the preparation of CaO-SrO-Na2O-Nb2O5-SiO2(CSNNS) glass-ceramics through conventional melting and high-temperature crystallization processes. Our investigation delved into the impact of crystallization temperature on the phase composition, dielectric properties, and energy storage characteristics of the CSNNS glass-ceramics. The results indicate a direct correlation between the dielectric constant and dielectric loss, both exhibiting an upward trend with increasing crystallization temperature. Simultaneously, the microstructure of the glass-ceramics manifests signs of deterioration, characterized by larger grain size and heightened porosity, leading to a reduction in breakdown strength. At a crystallization temperature of 1100 °C, the CSNNS glass-ceramics demonstrated a remarkable combination of a high dielectric constant (∼280) and superior breakdown strength (481 kV/cm). The achieved maximum theoretical energy storage density reached 2.87 J/cm3. At an electric field of 100 kV/cm, the effective energy storage density is 0.23 J/cm3, and the energy storage efficiency is 72 %. These findings demonstrate the broad application potential of the CSNNS glass-ceramics in the domain of pulse power, highlighting their relevance for future developments in this field.

Energy Storage Capacity Utilization in Redox Flow Batteries

Redox flow batteries (RFBs) are predicted to be a major contributing technology in the need for four-to-ten-hour energy storage. Other energy storage technologies, such as lithium-ion batteries, provide well-documented performance indicators such as efficiency and especially energy storage capacity utilization. While redox flow batteries are compared similarly based on cost and round-trip efficiency, they often neglect a comparison of their operational energy storage capacity utilization. The breakdown of operational losses that represent the current state of operation for RFBs are pivotal to further compare the development of these technologies to the standard of other electrochemical storage devices. Quantifying the current state-of-the-art in relation to the theoretical potential of RFBs allows us to assess the extent of development required to enhance their effectiveness in contributing to future energy storage goals.In this work, we set out to depict the operational energy storage density (W-h L-1) of various redox flow battery technologies based on consideration from experimental parameters and results from literature as key inputs. After reviewing five RFBs including the all-vanadium RFB, Hydrogen-Bromine RFB, All-Iron RFB, Zinc-Bromine RFB, and the Iron-Chromium RFB, results indicate that the VRFB is the most developed technology attaining around 60% of its theoretical energy storage density. While the Zinc-Bromine RFB has approximately the largest theoretical energy storage density (due to its high electroactive species concentration and standard potential difference), it is currently only able to operate at about a lowly 15% of it, dependent on its operational current density. We also assess the volumetric footprint for each RFB electrolyte system by considering a 6 MWh (6 MW, 1 hr) system. This assessment considers how large the electrolyte component of the RFB would be for operation. The Hydrogen-Bromine RFB would require electrolyte tanks to be more than 1600 m3 based on operational parameters, but if it were able to operate at 100% of its capability, the electrolyte tanks would shrink to be about 400 m3.

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.

Greatly enhanced energy storage density of alkali-free glass-ceramics after dual optimizations by thickness and crystallization temperature

Glass-ceramics show a great application potential in sustainable development, environmental protection, high temperature, high voltage resistance, and so on. Given the breakdown strength has a great contribution to the energy storage density, alkali-free niobate-based glass-ceramics have emerged as a prominent energy storage material. In this study, the 13.64BaCO3-13.64SrCO3-32.72Nb2O5-40SiO2 alkali-free glass-ceramics were optimized in thickness and crystallization temperature. The thinning of thickness improves the breakdown strength. At the same time, the dielectric constant gets a maximum value by adjusting the crystallization temperature. Therefore, an ultra-high theoretical energy storage density of 27.47 J·cm−3 is obtained. In addition, the finite element software simulates the electric field distribution and electric potential evolution during the development of electric branches, which illustrates the role of glass phase in hindering the development of electric branches and partaking the high electric field. Finally, the effective energy storage density obtained by using P-E loops is 1.49 J·cm−3 under 850 kV/cm.

High discharge energy density and ultralow dielectric loss in alkali-free niobate-based glass-ceramics by composition optimization

The SrO-BaO-Nb2O5-SiO2 glass-ceramics with different (Sr, Ba)/Nb ratio were prepared by the melting-crystallized process. With the decrease of (Sr, Ba)/Nb, the bonding species and crystallization activation energy of the glass-ceramics were changed obviously, which caused the change of phase compositions and microstructures on a microscopic scale and the fluctuations of dielectric constant and breakdown strength on a macroscopic scale. Finally, the theoretical energy storage density was up to 18.93 J/cm3 with a dielectric constant of 84 and breakdown strength of 2256.73 kV/cm. What is more, the dielectric loss was less than 0.004 at room temperature. Furthermore, under the electric field of 640 kV/cm the discharge energy density of the optimal sample (S5) reached 1.14 J/cm3 which overtopped what has been reported and the discharge time (t0.9) was less than 16 ns. Above analysis suggested that the alkali-free niobate-based glass-ceramics have broad application prospects.

Performance of isobaric adiabatic compressed humid air energy storage system with shared equipment and road-return scheme

• Novel isobaric adiabatic compressed humid-air energy storage system was investigated. • Water spray absorbs compression heat and controls compressed air outlet temperature. • Shared equipment and road-return scheme of energy storage/release system is employed. • Optimal system efficiency occurs at compression outlet parameters of 10 MPa/320 °C. • System efficiency reaches 72.6% and theoretic energy storage density is 17.2 kWh·m −3 . To cope with the inherent problem when intermittent renewable energies of solar and wind are connected to the grid, a novel isobaric adiabatic compressed humid air energy storage system was proposed and investigated. This system adopts a single stage dual-usage compressor-expander with synchronous rotating multi-cylinder to replace two separate multi-stage turbine type machines. The temperature of the compressed air is controlled by water spray before compression. The shared equipment with road-return stratagem of thermal oil energy storage/release system is employed. A hydro-assisted isobaric adiabatic compressed air storage system is formed with an underground cavern such as abandoned coal mine as the lower reservoir and a surface reservoir as the upper reservoir, and the nylon cloth pipe system is arranged in the underground cavern to store compressed air around water. By establishing the thermodynamic model of the system, the influences of the outlet pressure and temperature of compression on the system performance were analyzed determined respectively by the depth of the underground cavern and the working temperature of the thermal oil of the energy storage system. The results show that the round-trip efficiency varies slightly with the compression outlet pressure. Under the conditions of compression outlet parameters of 10 MPa/320 °C and the isentropic efficiencies in compression and expansion are 85%, the round-trip efficiency reaches 66.6% and the theoretical energy storage density is 16.5 kWh·m −3 .

Crystallization-temperature controlled alkali-free niobate glass-ceramics with high energy storage density and actual discharge energy density

The niobate-based alkali-free ferroelectric glass-ceramics were realized through the synthesis of mother glass by way of melt-annealing technique, followed by temperature-controlled crystallization. As the crystallization temperature raised, the ratio of the ferroelectric crystal phase precipitated in the mother glass enhanced continuously, resulting in the enlargement of the permittivity. Attribute to the rise of grain size, pores and cracks tend to appear in the microstructure of glass-ceramics with high crystallization temperature, leading to lower breakdown strength. The theoretical simulation was applied to reveal the internal mechanism, exploring the outcome of heat treatment temperature on the breakdown electric field. The maximum theoretical energy storage density reaches to 18.44 J/cm3 at the crystallization temperature of 800 °C. The single-layer capacitor made from the G800 sample exhibited extremely high power density (230 MW/cm3) and superior actual discharge energy density (1.5 J/cm3) at 600 kV/cm. These results indicate that alkali-free niobate-based glass-ceramics is a kind of encouraging candidate material for pulse capacitors.

Excellent energy storage performance of niobate-based glass-ceramics via introduction of nucleating agent

For glass-ceramics, how to realize the collaborative optimization of BDS and permittivity is the key to improve the energy storage density. In this work, ZrO2 is introduced into BPKNAS glass-ceramics as nucleating agent to promote crystal development of glass-ceramics and then achieve high permittivity. When 1.5 mol% ZrO2 is added, the glass-ceramics have the highest permittivity (∼128.59) and meanwhile possess high BDS (1948.90 kV/cm) due to the dense microstructure. Therefore, BPKNAS-1.5ZrO2 glass-ceramics has the highest theoretical energy storage density (21.62 J/cm3). Moreover, the permittivity variation of BPKNAS-1.5ZrO2 glass-ceramics is less than 6 % in the wide temperature range from −80 to 300 °C, showing excellent temperature stability. In addition, BPKNAS-1.5ZrO2 glass-ceramics possesses ultrahigh power density, which reaches up to 382.40 MW/cm3 in overdamped circuit. The above evidence shows that BPKNAS-1.5ZrO2 glass-ceramics with ultrahigh energy storage density and power density is very competitive in the field of energy storage applications.

Facile synthesized TiO2 with excellent electrochemical performances for lithium-oxygen batteries

Benefited from the super-high theoretical energy storage density, the rechargeable lithium–oxygen batteries (LOBs) are perceived as a shiniest energy conversion and storage devices with the highest potential. To gain the stable and long-life cycle performance and high-efficiency energy storage device, developing of non-toxic, environmental protection and price moderate cathode catalyst is a vital component to the application of the LOBs. Here, TiO2 nanomaterials, as low cost, environmentally friendly and effective cathode catalyst had been synthesized with a facile hydrothermal method and followed calcination processes. The structure, surface morphology and the growth mechanism of the as synthesized TiO2 nanotubes, TiO2 nanofibers were studied in detail. When they were applied as cathode materials for LOBs, TiO2 nanotubes exhibits better electrochemical performance and good cycling stability for over 132 cycles accompanied by a fixed capacity of 600 mAh g−1 at a current density of 200 mA g−1, which is better than the TiO2 nanofibers. The good performances could be originated from the high specific surface area and the large amounts of oxygen vacancy in the TiO2 nanotubes samples.

The effect of Hf doping on the dielectric and energy storage performance of barium titanate based glass ceramics

A series of (1-x) (BaO–TiO2–SiO2–Al2O3–B2O3)-xHfO2 (abbreviated as (1-x)BTSAB-xH) glass-ceramics were designed and prepared by traditional melt quenching and heat treatment method. The dielectric and energy storage properties of the glass-ceramics were studied systematically. The results of X-ray diffraction indicate that the main crystal phase of (1-x) BTSAB-xH glass-ceramics is BaTiO3. It should be noted that the addition of HfO2 can not only increase the dielectric constant, but also enhance the breakdown dielectric strength, resulting in high theoretical energy storage density. The max theoretical energy storage density can reach up to 7.07 J/cm3. The discharged energy storage density is 0.73 J/cm3 measured at 300 kV/cm @ room temperature. These results show that Hf doped barium titanate-based glass-ceramics are promising materials for application in dielectric capacitor with high energy storage density.

Effects of crystalline temperature on microstructures and dielectric properties in BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 glass-ceramics

The BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 (BNBN-AS) glass-ceramics were prepared by technics of melt-quenching accompanied with process of controlled crystallization. According to the X-ray diffraction results, NaNbO3 with perovskite structure and Ba2NaNb5O15 with tungsten bronze structure were all precipitated at four different crystalline temperatures. With the increasing of crystalline temperature, the relative dielectric constant kept increasing, while breakdown strength (BDS) increased first and then decreased. The highest relative dielectric constant of 123 at 1000 °C as well as optimal breakdown strength of 1878.75 ± 63.2 kV/cm at 950 °C were acquired in this system. The theoretical energy-storage density was markedly enhanced up to the maximum value of 18.4 ± 1.3 J/cm3 at 950 °C, which is approximately twice than that at 850 °C. The discharged energy density reached to 0.48 J/cm3 at the applied electric field of 600 kV/cm for the sample crystallized at 950 °C, which promises a broad application prospect.

The Energy Storage Density of Redox Flow Battery Chemistries: A Thermodynamic Analysis

The need for viable energy storage technologies is becoming more apparent as the amount of renewable energy being wasted increases. Here, we have provided an in-depth quantification of the theoretical energy storage density possible from redox flow battery chemistries which is essential to understanding the energy storage capacity of a battery system. This improved energy storage density model captures a wide range of conditions and reaction types based on fundamental electrolyte chemistry principles and thermodynamics. The model proposed here Requires standard Gibbs energy, activity coefficients, and state of charge limits. We also demonstrate that energy efficiency values can be incorporated to account for non-thermodynamic contributions. All-vanadium and iron-chromium redox flow battery chemistries were modeled using literature data to confirm the accuracy of the proposed approach. Excellent agreements were obtained between our modeling results and experimental energy storage values obtained from literature. Using this approach, we can precisely quantify the storage capacity possible with new chemistries and assess the tradeoffs we make by enhancing one property at the expense of another.

Enhanced energy-storage density in sodium-barium-niobate based glass-ceramics realized by doping CaF2 nucleating agent

The barium sodium niobate (BNN) glass-ceramics with different amount of CaF2 addition were fabricated by melting-crystallization method. Effects of CaF2 on microstructure, phase compositions, interface polarization, dielectric, energy-storage and charge–discharge properties of the BNN-glass-ceramics were comprehensively studied. Results indicate a suitable amount of CaF2 (from 1.0 to 3.0 mol%) is helpful to improve both relative permittivity and breakdown strength (BDS) of the BNN-glass-ceramics. The theoretical energy-storage density is up to 14.3 J/cm3 when the amount of CaF2 reaches 3.0 mol%. The optimal composition of 3.0 mol% CaF2 addition was further evaluated by a pulsed charged–discharged circuit and P–E hysteresis loops, from which we can conclude BNN-glass-ceramic is an excellent linear dielectric material. And the stored energy could be released within 50 ns and discharge power density reaches 75.6 MW/cm3. It’s for such results that the glass-ceremics with CaF2 addition are promising materials for pulse power applications.

Ultrahigh Energy Storage Density and Excellent Charge–Discharge Properties of Bi2O3-Nb2O5-SiO2-Al2O3 Glass Ceramic with CeO2 Doping

Bi2O3-Nb2O5-SiO2-Al2O3 glass–ceramic composites with different levels of CeO2 doping have been fabricated by controlled crystallization from a homogeneous glass matrix. The influence of the CeO2 doping level on the crystal phase, breakdown strength, microstructure, and energy storage performance was investigated. The results showed that the microstructure was clearly improved by CeO2 doping. A maximum theoretical energy storage density (J) of 20.9 J/cm3 was achieved in samples with 0.2 mol.% CeO2 doping, being clearly improved compared with samples without such addition (14.2 J/cm3). Also, the discharge time was found to be as short as 20 ns and the maximum power density exceeded 80 MW/cm3 under an electric field of 300 kV/cm. These results suggest that CeO2-doped Bi2O3-Nb2O5-SiO2-Al2O3 glass–ceramic composites are promising energy storage materials for use in pulsed-power systems.

Excellent energy storage and charge-discharge performances in sodium-barium-niobium based glass ceramics

Abstract The 21.25BaO–1PbO-12.75Na2O–34Nb2O5–32SiO2 glass ceramics and their singer layer capacitors were successfully prepared by the melt-quenching method and the high temperature crystallization technique. The study found that as the crystallization temperature increases, the relative permittivity increases gradually because of the precipitation of the phases with high relative permittivity, while the breakdown strength of the glass ceramics first increases and then decreases due to the effect of interfacial polarization. The theoretical energy storage density reaches up to a maximum value of 18.29 J/cm3 at the crystallization temperature of 950 °C. And the corresponding single layer capacitor can release the energy density of 0.79 J/cm3 within an ultrashort time (50 ns), the power density can reach to 131.12 MW/cm3 simultaneously in a LCR circuit. These results showed that this kind of glass ceramic is promising candidates for pulse power capacitor applications.

Dielectric characterization of a novel Bi2O3-Nb2O5-SiO2-Al2O3 glass-ceramic with excellent charge-discharge properties

A newly designed glass-ceramic system consisting of 15Bi2O3-15Nb2O5-40SiO2-30Al2O3 was successfully prepared, which was followed by its controlled crystallization at different heating temperatures. The effects of crystallization temperature on the microstructure, phase evolution and the energy storage behaviors of the novel material were systematically investigated. A maximum theoretical energy storage density of up to 15.3 J/cm3 was found in the samples heated at 800 °C. The polarization-electric (PE) hysteresis loops of this material exhibited very good linear character and high energy efficiency. In addition, an approximate value of 25 ns for discharged period T has been obtained, which demonstrated that most of the energy stored in dielectric was released over a very short time. The maximum powder density exceeds a high value of 90 MW/cc in a 390 kV/cm electric field. Therefore, the new developed Bi2O3-Nb2O5-SiO2-Al2O3 glass-ceramic can be used as an alternative, promising high-performance electrostatic capacitor material.

Crystallization Mechanisms and Energy-Storage Performances in BaO-SrO-Na2O-Nb2O5 Based Glass–Ceramics

The [x BaO, (1 − x) SrO]-Na2O (x = 0.0, 0.2, 0.5, 0.8) niobate-based glass–ceramics were prepared through the controlled crystallization method. Crystallization mechanism, phase structure, dielectric properties, and energy-storage properties were studied by adjusting Ba/Sr ratio. It was found that the surface and internal crystallization occurred simultaneously at first crystallization peak, while surface crystallization occurred at second crystallization peak. With Ba/Sr ratio increasing, dielectric constant increased firstly and then decreased, while dielectric loss firstly decreased and then increased. When x = 0.2, optimal dielectric constant of 88 and dielectric loss of 0.0055 were obtained, which is related to the solid solution phase Sr0.5Ba0.5Nb2O6. Breakdown strength (BDS) showed a behavior of increase before decrease. The highest BDS reaches 1975 kV/cm for x = 0.2, which is attributed to uniform and dense microstructure. Correspondingly, the theoretical energy-storage density was increased up to 15.4 J/cm3. Also, discharged efficiency reaches a high value of 91%. Discharged power density of 0.65 MV/cm3 was obtained for x = 0.2 in the RLC pulsed circuit.

Improvement of energy storage properties in niobate glass–ceramics via the adjustment of glass/ceramic ratios

Niobate glass–ceramics with varying amounts of glass have been prepared through a melted-quenching-controlled crystallization method. The influence of glass/ceramic ratio on the dielectric properties, energy storage characteristics and charge–discharge behavior of the [(SrO, K2O)–Nb2O5]–[SiO2–Al2O3] (SKN–SA) glass–ceramics was investigated. The microstructure showed that the grain size reduced with increasing aluminosilicate glass concentration. The dielectric properties illustrated that there was an opposite trend between the dielectric constant and breakdown strength with the increase of glass content. Based on these results, an optimal theoretical energy storage density of 6.70 J/cm3 could be obtained in the glass–ceramic sample with 45 mol% glass. For pulsed power capacitors, the discharge speed of the glass–ceramic samples decreased from 8.4 to 5.5 µs and the discharge–charge efficiency increased from 75.7 to 87.7% with the increase of glass content, which provided a new design strategy for pulsed power capacitors.

Enhanced energy storage properties of BaO-K2O-Nb2O5-SiO2 glass ceramics obtained through microwave crystallization

BaO-K2O-Nb2O5-SiO2 (BKNS) glass ceramics were prepared by microwave crystallization of transparent glass matrices and the effects of microwave treatment temperature on their dielectric performances, phase structure, microstructure and breakdown strength (BDS) were investigated systematically. X-ray diffraction results suggested that microwave treatment had no significant influence on the type of precipitated phases. The microstructure of the glass ceramics was remarkably optimized via microwave treatment. The dielectric constant and breakdown strength of microwave-treated samples were significantly improved as compared with conventional-heated samples at the same temperature. The maximum theoretical energy storage density of microwave-treatment samples at 750 °C reached 12.7 J/cm3, which was larger than that of the conventional-heated samples (8.6 J/cm3).

Crystallization kinetics behavior and dielectric energy storage properties of strontium potassium niobate glass-ceramics with different nucleating agents

A series of strontium potassium niobate (KSN-based) glass-ceramics with different nucleating agents have been prepared by conventional controlled crystallization method. The effects of different nucleating agents on crystallization kinetics behavior, dielectric properties and energy storage performances of glass-ceramics have been investigated. It was found that nucleating agents can improve the reaction rate constant (k) of crystallization, which made the KSN-based glasses crystallize at low temperature. Due to the increase of crystallinity, the dielectric constant rose and the breakdown strength decreased. The maximum theoretical energy storage density of 13.5 J/cm3 was obtained when 3 mol.% CaF2 were added as nucleating agents.