High Energy Storage Density Research Articles

Temperature stability and energy storage performances of Bi(Li1/3Hf2/3)O3-added BNT-based ceramics

The power electronics sector's growing demand requires the creation of energy storage systems with high recoverable energy storage density (Wrec) and efficiency (η). Although Bi0.5Na0.5TiO3 (BNT)-based ceramics are considered to be among the most promising dielectric materials, issues such as high energy loss (Wloss) and low breakdown strength (Eb) significantly affect their performance. Herein, the binary systems of (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35TiO3-xBi(Li1/3Hf2/3)O3 (BNBST-xBLH) are designed through the bandgap engineering and composition engineering strategies to achieve high Wrec and η. Consequently, the optimum composition of BNBST-0.15BLH delivers an optimally high Wrec of 4.3 J/cm3 and a desired conversion η of 92.3% at 370 kV/cm, while maintaining the variation of Wrec less than 9% and η less than 2%in the temperature range of room temperature (RT) to 200 °C. Combined with the extremely rapid discharge time τ0.9 of 74 ns and the high power density PD of 48.591 MW/cm3, the fabricated x = 0.15 ceramics are regarded to be viable lead-free options for practical applications.

A general comparison on energy density between Li-Ion, Li-S and Li-O2 batteries

Today, under the situation of the rapid development of EVs. Li-ion batteries is the first choice to power EVs than any other energy storage system. Many researches are done on various types of batteries with different theoretical and practical energy density and specific energy, where Li-O2 and Li-S battery are considered ultimate alternatives to Li-ion battery, mainly due to their high energy density. Basic mechanisms of these three types of batteries are introduced, and some of the recent researches being done on components of Li-ion battery is briefly discussed. Comparisons on energy density between these three types of batteries are made in the article, where Li-O2 battery has a highest theoretical and practical energy density, followed by Li-S battery, and finally Li-ion battery. By applying a high energy density storage system in EV can further expand the EV market, and hence tend to be potentially beneficial to the global environment.

A comprehensive study of Bi2Sr2Co2Oy misfit layered oxide as a supercapacitor electrode material

Recently, the development of multiple functional energy storage materials having high energy storage capacity, expanded stability, and cost-effectiveness with eco-friendly nature is primary choice. Bi2Sr2Co2Oy (BSC-222) is misfit-layered oxide having significant thermoelectric (TE) capability with high temperature stability and eco-friendly characteristics. In present work, we successfully synthesized misfit layered BSC-222 oxide by using sol–gel method. X-ray diffraction, scanning electron microscopy, and atomic force microscopy are used to describe the structure and morphology of calcined BSC-222. Average thickness of prepared oxide sheets was found to be ∼30 to ∼40 nm. By using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 3 M KOH, the electrochemical analysis of produced BSC-222 electrodes was carried out. The CV and GCD analysis showed that the BSC-222 oxide having high secondary cobaltite phases has better charge storage capacity (166.6C × g−1) at 2 mVs−1 and majorly charge is stored through diffusion-controlled charge storage mechanism. A chemical reactions schematic is proposed for the charge storage mechanism. Moreover, this calcined BSC-222 exhibits better cycling stability of 68.8 % up to 5000 GCD cycles at 1.5 Ag−1 current density. Hence, BSC-222 misfit layered oxide demonstrates that it has capability to store charge with its good TE ability. This present work provides the first step towards utilizing good TE misfit layered materials even after some doping or modulation in their structure to fabricate high energy density energy storage devices with multifunctional characteristics.

Diesel operated combined heat and power SOFC system: SOFC characterization and proof of concept

The high volumetric energy density and easy storage capability of liquid hydrocarbons such as bio-diesel or diesel are needed for power generation in several applications such as ships and isolated or rural areas which only have limited access to other power grids. Solid oxide fuel cells (SOFCs) can in theory utilize such fuels in a high efficient manner, which could reduce greenhouse gas emissions and energy demand. However, SOFC systems able to directly utilize diesel are rather complex to design and monitor, leading to several possible causes of system lifetime reduction. To avoid an enhanced reduction of the system lifetime, the operating conditions of all components must be optimized and monitored in detail. However, detailed monitoring and identification of the cause of performance loss are challenging using conventional system monitoring methods. Therefore, here we (i) show the concept and characterization of a SOFC system operating under steam- and auto-thermal diesel reforming conditions, (ii) demonstrated the applicability of advanced methods to monitor complex SOFC systems, which are applied on the 30 cell SOFC stack during system operation and (iii) analyzed the efficiency potential of the SOFC within the developed system. The results present in this work are favorable to accelerate commercialization.

Improving the High-Temperature Energy Storage Performance of Epoxy Films: Moderately Reducing Unsaturation for Extremely High Efficiency.

The rapid development of renewable energy systems, electric vehicles, and pulsed equipment requires energy storage media to have a high energy storage density and efficiency in a wide temperature range. The state-of-the-art biaxially oriented polypropylene (BOPP) film is insufficient to meet the growing demand for energy storage devices due to its low energy storage density and working temperature, which make it a research hotspot for developing dielectric energy storage materials. In this manuscript, based on the epoxy materials that have been shown as a potential energy storage medium, we aim to reduce the influence of the benzene ring delocalization structure on the energy storage losses and enhance the efficiency by gradually replacing them with cyclohexane structures to adjust the segment unsaturation of epoxy materials. The results show that by partially reducing the unsaturation of the curing agent, the epoxy material achieves an excellent high-temperature energy storage density of 2.21 J/cm3 at 150 °C and 300 MV/m while maintaining an extremely high energy storage efficiency of 99.2%. Leakage current density and high-voltage dielectric spectroscopy tests confirm that a moderate reduction of the segment unsaturation of epoxy materials can greatly inhibit polarization loss at high temperatures, which may explain their high energy storage efficiency.

Development and Characteristics Analysis of Novel Hydrated Salt Composite Adsorbents for Thermochemical Energy Storage

New composite adsorbents are proposed to further improve the application of thermochemical energy storage technology in buildings. A volcanic is taken as an adsorption substance, which is impregnated in 36.50 wt% and 54.00 wt% saturated MgCl2 and CaCl2 solutions to prepare composite adsorbents, which are called composite-MgCl2 and composite-CaCl2, respectively. According to the characterization, the main pore structure of the original volcanic is macropores (>100 nm), and hydrated salts tend to fill them. Compared with zeolite-MgCl2, the final water uptake of composite-MgCl2 and composite-CaCl2 increased by 0.15 g/g and 0.03 g/g. Meanwhile, the TG-DSC measurement results show that the thermochemical energy storage densities of composite-MgCl2 and composite-CaCl2 are 1.02 and 1.56 times that of zeolite-MgCl2, which are 642 kJ/kg and 983 kJ/kg, respectively. Moreover, the composition of the thermochemical energy storage densities of the composites is obtained by theoretical calculations, and the theoretically calculated results are close to the measured results. After several cycles, the composites still have high thermochemical energy storage capacity and low energy storage density cost.

Antiferroelectric-like BiFeO3-SrTiO3 based ceramics with high breakdown strength and energy-storage density

Herein, an outstanding excellent energy storage performance (ESP) (Wrec∼4.4 J/cm3; η∼72%; ΔP = 38.1 μC/cm2) was obtained in environmentally friendly 0.52BiFeO3-0.4SrTiO3-0.08NaNbO3 lead-free ceramic. First, the addition of NaNbO3 (NN) lead to composition and charge disorder of A- and B- sites, generating random electric field that induce the emergence of small-sized polar nano-regions (PNRs) to enhance ΔP (Pmax-Pr). Rietveld refinement analysis showed that introducing NN reduces the content of polar R3c phase from 81.8% to 24.4%, and the non-polar Pm3m phase increased. When x ≥ 0.08, the antiferroelectric-like double P-E loops were acquired due to field-induced phase transition, and further lower Pr and Ec were obtained. Then, the introduction of NN greatly improved the breakdown strength of BFO-STO ceramics. That is, enhances electrical homogeneity, increases energy gap (Eg) and refines grain size (from 1.05 to 0.75 µm). Through domain engineering, antiferroelectric-like design and other multi-factors to achieve the optimization of ESP, providing a feasible strategy for lead-free pulse energy storage capacitors. Additionally, the good temperature (20–120 °C) and frequency (1–100 Hz) stability acquired to less than 15% in favor of practical applications.

Experimental heat transfer study of an enhanced storage medium

Phase change materials (PCMs) are suitable for storing solar energy due to their high-density energy storage and ability to operate in a wide range of temperatures. However, the lower thermophysical properties of PCMs limit their use in solar energy storage applications. Therefore, the incorporation of nanoparticles has emerged as a promising technique to enhance the storage density of PCMs.Extensive studies have been conducted on the measurement of thermophysical properties of both PCMs and nano-PCMs (PCMs with nanoparticles dispersed in them). However, there has been no comprehensive study covering the following aspects: (a) the measurement of thermophysical properties of NaNO3 (PCM) and nano-NaNO3 (nano-PCM), (b) solar energy storage of NaNO3 involving both sensible heat and latent heat in the same study, (c) the construction and implementation of an experimental rig capable of studying heat transfer in PCM and nano-PCM for solar energy storage applications (with a maximum temperature of up to 350 °C), and (d) investigating the effect of nanoparticles on large-scale solar energy storage systems. Therefore, the aim of this study is to experimentally investigate all of the aforementioned points. In order to develop and test these solar storage mediums, an experimental setup has been designed and manufactured, as mentioned earlier.Furthermore, limited studies have considered sodium nitrate salt (NaNO3) as a PCM. In this study, NaNO3 is used as the base material, and two types of materials are considered: PCM1, which consists of sodium nitrate salt (NaNO3), and PCM2, which consists of sodium nitrate salt (NaNO3) with 0.75 wt% iron oxide nanoparticles (Fe2O3) added. The experiments conducted involved both steady-state and transient conditions. The results showed that the addition of nanoparticles improved the charging and discharging by 25.6 % and 23.929 %, respectively. Moreover, the specific heat capacity and latent heat of the developed PCMs increased by 17.857 % and 9.97 %, respectively. These findings suggest that PCM2, with the presence of nanoparticles, melts and discharges energy faster compared to PCM1. Overall, this study contributes to the understanding of solar energy storage using PCMs and nano-PCMs, highlighting the potential benefits of nanoparticle incorporation in enhancing their performance.

Miniature soft jumping robots made by additive manufacturing

Abstract Fleets of insect-scale robots could navigate space-constrained environments for future applications in agriculture and maintenance. Long distance jumping expands the mobility of small robots. However, the performance of miniature jumpers is hindered by small-scale manufacturing processes and the limited library of design rules, materials, and actuators available at that scale. The intricate components in these robots are produced by manual assembly of miniature components, which imposes design constraints and causes mass inefficiency, reducing the overall system performance. Here, we combine bioinspired kinematic design, coiled artificial muscle actuators, and projection additive manufacturing (AM) to produce a monolithic elastomeric robot design. The fully elastomeric design, inspired by the kinematics of the locust jumping mechanism, can store elastic energy throughout the robot body before releasing it in the form of jumping kinetic energy, thus offering high energy storage density, miniaturization, and lightweight. Enabled by high-speed, production-grade AM, we designed and tested a fleet of 108 robot designs. The smallest tested robot has a length of 7.5 mm, a mass of 0.216 g, and jumps 60 times its body size in horizontal distance. A reduced-order model is developed to predict the compliant robot jumping distance, which agrees well with the experimental results. The jumping is driven by onboard coiled artificial muscles connected to a latch-triggering mechanism. Moreover, the robot can jump while carrying an integrated control system and power source to enable self-triggered jumping. A proof-of-concept motor-driven launch base is used to store large elastic energy in the robot. Overall, the combination of elastomeric AM, coiled artificial muscles, and an integrated triggering mechanism enables the production of fleets of high-performing miniature jumping robots.

Giant Energy Density via Mechanically Tailored Relaxor Ferroelectric Behavior of Pzt Thick Film.

Relaxor ferroelectrics (RFEs) are being actively investigated for energy storage applications due to their large electric-field-induced polarization with slim hysteresis and fast energy charging-discharging capability. Here, w e report a novel nanograin engineering approach based upon high kinetic energy deposition for mechanically inducing the RFE behavior in a normal ferroelectric Pb(Zr0.52 Ti0.48 )O3 (PZT), which results in simultaneous enhancement in the dielectric breakdown strength (EDBS ) and polarization. Mechanically transformed relaxor thick films with 4μm thickness exhibited an exceptional EDBS of 540 MV/m and reduced hysteresis with large unsaturated polarization (103.6 μC/cm2 ), resulting in a record high energy storage density of 124.1 J/cm3 and a power density of 64.5 MW/cm3 . This fundamental advancement is correlated with the generalized nanostructure design that comprises of nanocrystalline phases embedded within the amorphous matrix. Microstructure-tailored ferroelectric behavior overcomes the limitations imposed by traditional compositional design methods and provides a feasible pathway for realization of high-performance energy storage materials. This article is protected by copyright. All rights reserved.

Electrode-supported high-tortuosity zeolite separator enabling fast-charging and dendrite-free lithium-ion/metal batteries

Lithium-metal batteries (LMBs) are poised to be the next-generation high-energy density storage media of choice for various applications; however, they are currently plagued by failure due to dendrite propagation at high charge/discharge rates. One of the most sought-after technologies for dendrite propagation prevention in LMBs is solid state batteries, but they face commercialization challenges due to low room temperature ionic conductivity and high manufacturing cost. Here, we report the use of plate-shaped zeolite particles with intraparticle crystalline micropores to form an electrode-coated separator by a scalable blade-coating methodology. These separators with minimal polymer content are non-flammable and highly wettable to organic-based liquid electrolytes. They have high pore tortuosity and shear modulus resulting from the unique physical properties and morphology of the plate-shaped zeolite particles. LMB cells made of a LiNi0.5Co0.2Mn0.3O2 (NMC) cathode, coated with the plate-shaped zeolite separator, LiPF6-carbonate electrolyte, and lithium metal anode, show good charge-discharge characteristics and effectiveness in preventing dendrites from propagating through the separator even at high (3 C-rate) rates. When compared to LMB cells with a tortuously porous separator of similar pore size and porosity made of dense plate-shaped γ-alumina particles without intraparticle pores, cells with the zeolite separator show better charge/discharge characteristics, lower solid electrolyte interface (SEI) and charge-transfer resistances, and more effective dendrite propagation prevention. Results suggest that the intraparticle pores of the zeolite separator particles homogenize the Li-ion flux at the separator-anode interface in a much better manner than γ-alumina particles. There is promising commercial potential for the electrode-coated zeolite separator with highly tortuous pores for lithium batteries with a lithium-metal anode.

Porous Structure Induced Dielectric Loss Suppression for CB-g-PFOTES/PVDF Composites

Polymer-based dielectrics have long been the focus of research in the field of flexible thin-film capacitors. However, the low energy storage density of polymer-based dielectrics has been an obstacle for practical applications, since the enhancement of the dielectric constant is often accompanied by an increase in the dielectric loss. In this study, a novel core–shell structured CB-g-PFOTES nanoparticles with porous carbon black (CB) as the core and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES) as the outer shell were successfully synthesized and further embedded into polyvinylidene fluoride (PVDF) matrix. As a result, the core–shell structured CB-g-PFOTES nanoparticles displayed notable improvements in the dielectric properties of composites. Typically, the CB-g-PFOTES/PVDF composites with a filler content of 2.5 wt% exhibited outstanding dielectric properties with a high dielectric constant of 33.2 and an extremely low dielectric loss of 0.0238 at 102 Hz. The significant suppression of dielectric loss was due to the fact that the porous structure of the CB effectively limits the interfacial charge transfer within the polymer matrix. This work provides a novel type of nanofiller for the fabrication of high dielectric nanocomposites, which is expected to further realize application in high energy storage density dielectric materials.

Energy storage and multiferroic properties of La-doped epitaxial BiFeO3 thin films according to La doping concentration

La-doped epitaxial BiFeO3 (LBFO) thin films with La doping concentrations of 0, 10, 20, 25, and 30 % were deposited by pulsed laser deposition on Nb-doped single-crystal SrTiO3 substrates. The LBFO thin films doped with a La doping concentration of 10 % showed the best ferroelectric properties due to a large c/a ratio of about 1.04. As the concentration of La increased, the ferroelectric polarizations of the LBFO films decreased while the ferromagnetic properties steadily improved. In particular, the LBFO thin films tended to increase energy storage efficiency as the concentration of La increased, and the LBFO thin films with a La doping concentration of 30 % showed a high energy storage density of about 30.7 J/cm3.

Excellent energy storage performance with outstanding thermal stability assisted by interfacial resistance of aramid-based flexible paper capacitors

Polymer-based dielectric energy storage capacitors show more potential than conventional rigidity ceramic-based capacitors. Recent studies were classified into two categories: the excellent room temperature performance in poly (vinylidene fluoride) (PVDF) systems and the enhanced thermal stability in polyimide-based systems. Only now, however, both of them are still far from commercial use because of their inferior heat resistance or poor processability. By adding BaTiO3 (BT) particles in maturely used aramid nanofibers, we synthesized the aramid nanofiber (ANF)/BT-based flexible paper capacitors through a convenient industrialized technology in this work. Due to the intrinsic laminated structure of ANF and the uniform distribution of BT particles, the composite film with BT addition of 8 vol% exhibits outstanding dielectric thermal stability. With the help of the interfacial resistance in the organic–inorganic interface, which protected the ANF matrix from being breakdown too early by optimizing the electrical field distribution, a high and stable energy storage density of 6.70 J/cm3 was obtained in ANF/BT5. In addition, excellent energy storage frequency stability with ultrafast discharge speed was also achieved. This work offered a highly repeatable way to synthesize commercially used flexible capacitors, bridging the lab investigation and commercial use in high-power density energy storage polymers.

Enhancing thermal performance of latent heat storage unit for solar cooling: A hybrid approach with C-shaped fins and nano-additives

The performance of solar cooling systems is significantly affected by the intermittent nature of solar energy. To address this problem, thermal energy storage systems such as sensible and latent heat storage systems can be a viable option. Among these, the latent heat storage systems are promising due to their high energy storage density and nearly isothermal charging/discharging characteristics. However, the low thermal conductivity of the phase change material used within the storage unit hinders heat transfer, leading to longer charging and discharging periods. To overcome this problem, a hybrid approach that uses fins and nano additives is proposed in this study. A novel C-shaped fin design is introduced that effectively utilises the natural convection current in the molten phase change material. A comprehensive geometrical and material optimisation study is performed to determine the optimal shape, position, and material of the fins. The study also investigates the effect of the inclusion of graphene nanoplatelets (GnP) on the latent heat storage units. An experimental study is conducted to characterise the composite phase change material, and empirical correlations for viscosity and thermal conductivity are developed. The performance of an optimally designed LHS stacked with nano PCM composite of varying mass fractions is also evaluated. The study reveals that the C-shaped fins can reduce melting time by up to 59% compared to conventional fin designs, while PCM dispersed with 1% GnP reduces melting time by 27% when compared to the base PCM. Finally, a two-bed solar vapour adsorption cooling system with a 500 W capacity is considered to conduct a case study for demonstrating the performance of the proposed LHS. The result shows that the solar adsorption system integrated with the proposed heat storage unit can operate up to 3.3 h longer than it currently does. Thus the study presents a promising solution to overcome the obstacles limiting the widespread utilisation of solar cooling systems.

Recycling of aluminium scrap into phase change materials for high-temperature storage applications: Thermophysical properties and microstructural characterisation

Metal scrap is often generated during conventional production processes and at the end-of-life of metallic components finding use as a recycled metal source. However, the impurities introduced in the recycling process can deteriorate the mechanical properties of the final product leading to down-cycling from structural applications or requiring great effort to make the material viable again.Metallic phase change materials (mPCMs) are promising materials due to their high energy storage density and high thermal conductivity relative to common inorganic and organic thermal storage materials. Metals used for thermal applications, such as mPCMs do not have strict mechanical requirements, and could potentially be made from recycled sources unsuitable for structural significant applications. Thermal storage offers an alternative use for scrap sources, especially aluminium alloys which according to the International Energy Agency are among the metals with the highest recovery rates.AlSi cast alloys are widely used in different applications, especially the automotive industry. In this work, the eutectic composition Al-12.6 wt% Si has been proposed as thermal storage material due to the great potential and excellent storage properties in the temperature range 500–600 °C. Thermophysical properties including melting temperature, heat of fusion, heat capacity and thermal diffusivity were experimentally determined via Differential Scanning Calorimetry (DSC) and Light Flash Analysis (LFA) in order quantify the impact of impurities typically present in commercial aluminium alloys such the 2000 and 3000 series.Four different AlSi alloys with different impurity levels from scrap-equivalent compositions were investigated as candidate materials for latent heat storage applications and their potential contribution in the circular economy.

Development of Fuel Cell System Using Metal Hydride and Hydrogen Peroxide in Low-Oxygen Environments

Hydrogen energy is attracting attention as a promising power system due to high energy storage density and environmentally friendly features. For these reasons, fuel cell system using hydrogen energy in unmanned underwater vehicles have been studied. However, in low-oxygen environment, fuel cell system requires an oxygen storage as well as a hydrogen storage. In this study, a fuel cell system using a metal hydride and hydrogen peroxide was designed. The metal hydride can charge and discharge hydrogen at a lower pressure than a high-pressure hydrogen tank and has a high hydrogen storage density. In this system, AB2 type metal hydride is used to store hydrogen. Hydrogen desorption reaction of the metal hydride is an endothermic reaction, and heat supply is required to maintain the temperature of the metal hydride in order to stably supply hydrogen. Therefore, in this system, hydrogen peroxide was used as an oxygen source. Hydrogen peroxide reacts with a metal catalyst to generate oxygen and water. The decomposition reaction of hydrogen peroxide is an exothermic reaction and can supply heat required for the metal hydride. In this system, hydrogen peroxide is decomposed into water and oxygen through a catalytic reaction, and the generated heat is supplied to the metal hydride. Finally, hydrogen and oxygen are supplied to the PEMFC stack to generate power. For system design, in this study, PCT characteristics of AB2 type metal hydride, thermal management method, and hydrogen peroxide decomposition catalyst were studied, and an operation strategy for non-humidified PEMFC operation was proposed. This system generated a power output of about 290 W for 97 hours, and the hydrogen utilization rate of the fuel cell was confirmed to be 92.3%.

Local Environments in Inorganic Oxide Solid Electrolytes

All-solid-state batteries using inorganic solid electrolytes have been attracting great attention due to their enhanced stability and high volumetric capacity for the increased demand for high energy storage density and good operational safety for large-scale use[1]. However, crystalline electrolytes inevitably contain various kinds of non-periodic features (e.g. grain/domain boundaries, point defects) as a result of synthesis[2,3]. Since these defects have a significant effect on the overall conductivity, it is necessary to understand the local structure and ionic transport of crystalline electrolytes. For example, in lithium lanthanum titanate (Li3xLa2/3-xTiO3, denoted as LLTO), the random distribution of vacancies and La disorder creates a series of different local environments which affect the ionic mobility, following random walk theory[4,5]. While the movement of mobile ions is influenced by both the local chemical and structural environment, few methods exist that can directly observe the connection between the two[4].In this talk, we report the local chemical and structural environments of LLTO using aberration-corrected scanning transmission electron microscopy (STEM), and investigate their effect on ion mobility. Direct imaging is used to determine the dominant structural factors related to the ion migration. As shown in the STEM image in Fig. 1a, the simultaneously acquired ADF (annular dark field) and iDPC (integrated differential phase contrast) enable correlating the La/Li-site chemical distribution (Li/La/vacancy) and O bottleneck size. In addition, La/Li migration under the high energy electron beam induces a change of bottleneck size with a change in the La/Li-site chemical environment, revealing a direct relationship between the site chemistry and lattice distortion (Fig. 1b). Directly mapping the bottleneck size along with the local chemistry also enables direct comparisons with density functional theory (DFT) and molecular dynamics (MD). They show that the Li hopping mechanism is associated not only with Li itself but also with La, Ti, and O sublattices, suggesting that the structural changes along with the La/Li-site distribution can have a significant effect on Li transport and vice versa. This study of the local environment with high spatial and temporal resolution can serve as a cornerstone for a comprehensive and complete understanding of ion migration dynamics and establishing universal guidelines for further enhancement of ion conductivity.

Superior energy storage performance and excellent multiferroic properties of BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) ceramics

Ceramic based capacitors with superior energy storage performance and high storage energy density play an important role in modern electronic devices. Several ferroelectric materials with high dielectric constant and relaxor behavior become the most promising systems for realizing higher energy storage performance. In the present work, environmentally lead-free BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) nanostructures were synthesized using the sol-gel auto-combustion process. The doping of Gd at the Ti site causes the transformation of the ferroelectric behavior to the relaxor ceramics, which is important for finding the large energy storage efficiency of the material. The surface morphology of undoped and doped samples was examined through the SEM studies. Ferroelectric study evidence that the system is going to a more symmetric phase due to a reduction in the polarization parameters and enhancement in the leakage current density. Moreover, the energy discharge density and energy storage efficiency were boosted in x = 0.02 and x = 0.04 samples with energy storage efficiencies reaching ∼81% and 83%, respectively. The linear enhancement in the magnetic moment and the dielectric constant in the doped sample make the system favorable for multifunctional applications. The samples' piezoelectric constant (d33) remains preserved under Gd doping. Hence, the present study opens a propagable and feasible route to synthesize novel lead-free ferroelectric material for energy storage applications.

Densification, Precipitation, and Dissolution of Vanadium Electrolyte for Vanadium Redox Flow Battery Systems

The all-vanadium redox flow battery system (VRFB) is the most mature RFB technology since it uses a single active species, which does not degrade. Rebalancing electrolytes to maintain maximum energy capacity in an RFB system that uses a single active species, or symmetrical electrolytes, is simple and enables the use of relatively low-selectivity separators, which have higher ionic conductivities.1 Conversely, finite-lifetime RFB chemistries, especially asymmetric chemistries, result in significant negative impacts on the levelized cost of storage (LCOS).2 Currently, the vanadium electrolyte used in a MWh-scale VRFB system is typically shipped to the installation site in liquid form in multiple totes and the VRFB-system tanks are filled onsite. A new approach explored in this study is to densify and precipitate the electrolyte in a solid form, which can then be quickly dissolved to its intended concentration onsite by the addition of de-ionized water.3 This approach can enable multiple benefits. First, shipping the electrolyte in solid form provides more stability and higher density during shipping, which significantly reduces shipping costs. Second, the solid electrolyte can be shipped in the actual containers that will be used onsite, which thus simplifies the required onsite work. This presentation will discuss a method used to densify the vanadium electrolyte, as well as nucleation and precipitation processes that generate the solid electrolyte form, which will quickly dissolve when deionized water is added onsite. The nucleation and precipitation process leverages recent work on the solid-liquid high-energy storage density method for RFB systems.4 References M. L. Perry, J. D. Saraidaridis, and R. Darling, “Crossover Mitigation Strategies for Redox-Flow Batteries,” Current Opinion in Electrochemistry, 21 (2020). 10.1016/j.coelec.2020.03.024 K. E. Rodby, M. L. Perry, and F. R. Brushett, “Assessing Capacity Loss Remediation Methods for Asymmetric Redox Flow Battery Chemistries Using Levelized Cost of Storage,” J. Power Sources, 506 (2021). 10.1016/j.jpowsour.2021.230085 M. L. Perry, Provisional U.S. Patent Application 63/312,999 filed on Feb. 2, 2022.Yuanchao Li and Trung Van Nguyen, “A Solid/Liquid High-Energy-Density Storage Concept for Redox Flow Batteries and Its Demonstration in an H2-V System,” J. Electrochem. Soc., 169 (2022). 10.1149/1945-7111/ac97c6