Enhanced Energy Storage Performance Research Articles

Engineering multi-ion doping by entropy for high energy storage density with high efficiency in amorphous thin film

In the field of stored energy materials, lead-free amorphous thin films have the advantages of high breakdown strength, excellent stability, environmental protection and pollution-free, and are a very competitive energy storage material. However, the difficulty of simultaneous optimization of polarization and breakdown strength has always been a difficulty in improving the energy storage properties of amorphous thin films. Entropy can be used to design multi-ion doping to improve the energy storage performance of amorphous film. Amorphous films with different entropy are prepared by sol-gel method doped with 50 % Zr4+ and 5 %, 10 %, 15 %, 20 % Bi(Mn0·5Ti0.5)O3. The Bi0·1Ba0·85Sr0·05Mn0·05Ti0·45Zr0·5O3 amorphous thin film prepared at medium entropy (S = 1.37) has a recoverable energy storage density of 107.4 J cm−3 at 8.42 MV cm−1, and the energy storage efficiency is 93.9 %. Under the interaction of multiple elements, entropy design can give full play to the advantages of composite effects, improve breakdown field strength and energy storage efficiency, and is a new method to enhance energy storage performance.

Enhanced energy storage performance in Pb-free Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3-based relaxor ferroelectric ceramics through a stepwise optimization strategy

This study employed a stepwise optimization strategy, including doping Sr(Ga0.5Nb0.5)O3 (SGN) into 0.65Na0.5Bi0.5TiO3-0.35Sr0.7Bi0.2TiO3 (NBT-SBT) ceramics to modify the composition and a further processing improvement. By introducing Ga3+ and Nb5+ ions with high ionic polarization rates into the B-site, the average polarization of the unit cell was maintained while further inducing local disordered fields and promoting polar nanoregions. The high activity of the polar nanoregions was confirmed using piezoelectric microscopy. The effective energy storage density (Wrec) of 2.73 J/cm³ was obtained when the SGN doping was 6.5 %. Subsequently, the densification of ceramics was improved through viscous polymer processing, thereby enhancing the breakdown strength (BDS). A combined approach of finite element simulation and experimental studies was further utilized to investigate the impact of grain size on the BDS. The stepwise optimization strategy enabled the NBT-SBT-6.5SGNVPP ceramics to achieve the Wrec of 5.2 J/cm3 and efficiency (η) of 85 % under 350 kV/cm. Additionally, the ceramics developed by this strategy possess excellent temperature and frequency stability and pulse discharge performance, making them potential candidates for practical applications.

Enhanced energy storage performance, breakdown strength, and thermal stability in compositionally designed relaxor Eu3+ substituted Na0.2K0.3Bi0.5TiO3

Lead-free Eu3+ substituted NKBT ceramics (Na0.2K0.3Bi0.5-xEuxTiO3, x = 0 (Eu 0),0.02(Eu 2),0.04(Eu 4), and 0.06(Eu 6)) were strategically designed via a local random field approach. The structural evolution had been confirmed through X-ray diffraction analysis. The observation of a broad dielectric curve supported the enhanced relaxor nature and the phenomena reflected in the P-E and S-E loops. The diffuse phase transition transforms to the plateau-type feature with excellent thermal stability with ±20 % and ± 40 % variation in dielectric constant over the temperature range of 120 to 500 °C and 90 to 500 °C, respectively in Eu 4. A large recoverable energy density of 1.7 J/cm3 with a high breakdown strength of 188 kV/cm was achieved in the Eu 2 sample at room temperature, making it a potential candidate for energy storage application. Moreover, the frequency stability (0.1 to 500 Hz range), thermal stability (45 °C to 85 °C), and fatigue measurement (10−1 to 106 cycles) were performed from the application point of view. The highest efficiency (82 %) was also achieved in the Eu 6. The negligible Sneg of Eu-rich compositions proves the existence of a relaxor state when the field is removed, and it transforms into the ergodic relaxor state. Furthermore, the SRBRF model is exploited to understand and correlate the transformation from normal to relaxor ferroelectrics with their properties. The current study provides a novel idea for compositional design for energy density, efficiency, and thermal stability ceramics by modifying and creating weakly coupled polar phases with rare earth substitution.

Achieving ultrahigh energy storage performance of PBLZST-based antiferroelectric composite ceramics via interfacial polarization engineering

Antiferroelectric (AFE) ceramics can be used in pulse power devices for high power density and fast discharge. Composites are recognized as an effective strategy to combine the benefits of different materials but suffer from interfacial mismatch and interfacial polarization. In this work, a combination of high-breakdown Pb0.94La0.04(Zr0.99-xSnxTi0.01)O3 (PLZST) with high-efficiency Pb0.8925Ba0.04La0.045(Zr0.65Sn0.3Ti0.05)O3 (PBLZST) is explored to enhance energy storage performance. Via adjusting Sn content in PLZST, the difference in lattice and dielectric properties between two phases are reduced, decreasing interfacial polarization. The breakdown strength of PBLZST-PLZST is boosted from 285 kV cm−1 to 345 kV cm−1, with maximum polarization strength decreasing from 44 μC cm−2 to 36 μC cm−2. An recoverable energy density (Wre ∼ 7.152 J cm−3) and discharged efficiency (η ∼ 90.5%) has been achieved in Pb0.8925Ba0.04La0.045(Zr0.65Sn0.3Ti0.05)O3-Pb0.94La0.04(Zr0.69Sn0.3Ti0.01)O3 (x = 0.3) composite ceramics. These findings highlight the potential of interfacial polarization engineering for developing composite ceramics with high-energy storage performance.

Enhanced Energy Storage Performance through Controlled Composition and Synthesis of 3D Mixed Metal-Oxide Microspheres.

Binary transition metal oxide complexes (BTMOCs) in three-dimensional (3D) layered structures show great promise as electrodes for supercapacitors (SCs) due to their diverse oxidation states, which contribute to high specific capacitance. However, the synthesis of BTMOCs with 3D structures remains challenging yet crucial for their application. In this study, we present a novel approach utilizing a single-step hydrothermal technique to fabricate flower-shaped microspheres composed of a NiCo-based complex. Each microsphere consists of nanosheets with a mesoporous structure, enhancing the specific surface area to 23.66 m2 g-1 and facilitating efficient redox reactions. When employed as the working electrode for supercapacitors, the composite exhibits remarkable specific capacitance, achieving 888.8 F g-1 at 1 A g-1. Furthermore, it demonstrates notable electrochemical stability, retaining 52.08% capacitance after 10,000 cycles, and offers a high-power density of 225 W·kg-1, along with an energy density of 25 Wh·kg-1, showcasing its potential for energy storage applications. Additionally, an aqueous asymmetric supercapacitor (ASC) was assembled using NiCo microspheres-based complex and activated carbon (AC). Remarkably, the NiCo microspheres complex/AC configuration delivers a high specific capacitance of 250 F g-1 at 1 A g-1, with a high energy density of 88 Wh kg-1, for a power density of 800 W kg-1. The ASC also exhibits excellent long-term cyclability with 69% retention over 10,000 charge-discharge cycles. Furthermore, a series of two ASC devices demonstrated the capability to power commercial blue LEDs for a duration of at least 40 s. The simplicity of the synthesis process and the exceptional performance exhibited by the developed electrode materials hold considerable promise for applications in energy storage.

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Enhanced energy storage performance in Bi4Ti3O12 thin films with oxygen depletion layers

The imprint effect in ferroelectric materials can significantly enhance the performance of energy storage devices. Bi4Ti3O12 (BTO) and oxygen-deficient Bi4Ti3O11.2 (DBTO) thin films were deposited on single-crystal Nb-doped SrTiO3 substrates using pulsed laser deposition. In stark contrast, multilayer DBTO/BTO thin films incorporating an oxygen-deficient layer were also fabricated, with the DBTO layers having thicknesses of 5 nm and 10 nm, respectively. Both BTO and DBTO thin films exhibited epitaxial growth and c-axis-oriented crystallinity. Regarding ferroelectric properties, DBTO/BTO capacitors with an oxygen-deficient layer demonstrated a pronounced imprint effect in their ferroelectric hysteresis loops, compared to the BTO and DBTO capacitors. This effect was particularly noticeable in the DBTO/BTO capacitor with a 10 nm oxygen-deficient layer, as opposed to the thin film with a 5 nm oxygen-deficient layer. We suggest that the imprint effect can be attributed to localized electric field variations and imbalances in charge transport at the interface between the oxygen-depleted layer and the remaining thin film. Consequently, the imprint effect observed in the DBTO/BTO capacitors contributed to an enhancement in energy storage density and efficiency, compared to BTO and DBTO capacitors. This study demonstrates the potential of multilayer DBTO/BTO thin films in advancing capacitive energy storage systems.

Enhancement effects of hydrolysable/soluble Al-type dopants on the efficiency of CaO/CaCO3 thermochemical energy storage

Modification of CaO-based materials using Al-type dopants has been considered a promising method to enhance energy storage performance. The synergistic multi-doping effects of different Al-type dopants (soluble, hydrolysable and insoluble) on the energy storage performances, thermophysical and mechanical properties of CaO-based materials have never been reported. The hydrolysable/soluble Al-type supports co-doped CaO-based pellets were prepared, which exhibited superior energy storage density, multi-cycle stability, reaction rate, thermal conductivity and crushing strength compared to undoped CaO pellets. The regulation mechanisms of hydrolysable/soluble Al-type dopants (AlN/Al(NO3)3) on the reaction kinetics, multi-cycle stability, thermophysical properties and mechanical properties of CaO-based pellets were revealed. The addition of different Al-type dopants results in different dispersions of the formed Ca12Al14O33, which leads to different micro-morphologies and pore structures of CaO-based pellets. Hydrolysable Al-type dopants exhibit a more concentrated distribution in CaO-based pellets and the pellets have smaller crystallite sizes of CaO and predominantly microporous pores, which results in the high CO2 reactivity. Soluble Al-type dopants exhibit a more uniform dispersion in CaO-based pellets and the pellets have larger crystallite sizes of CaO and obvious pore channels, which results in the improved cyclic stability and decomposition kinetics. The optimized CaO-based pellets combine the advantages of the two Al-type dopants and present an increasing trend of energy storage density during the cyclic process. Its energy storage density remains 1571 kJ/kg after 50 cycles, and the value for CaO is only 569 kJ/kg. In addition, the optimal synthesized material has excellent thermal conductivity and crushing strength, which are 1.36 and 9.75 times those of CaO, respectively.

Interface behavior in negative current collectors for sodium‖zinc liquid metal batteries: Implications for enhanced energy storage performance

All-liquid structure and elevated operational temperatures of liquid metal batteries (LMBs) cause severe corrosion of the current collector, impacting cycling performance. This investigation explores the interaction behaviors between negative current collectors (Mo, W, Fe) and the negative active material (Na) within Na|NaCl-CaCl2|Zn LMB. Experiment results indicate that the Na|NaCl-CaCl2|Zn LMB with Fe current collector displays higher cycle stability and smaller polarization than that using Mo or W current collector. The capacity fading rates of 1.23 %, 1.03 %, and 0.23 % in 40 cycles for Mo, W, and Fe current collectors, respectively. Characterizations of materials indicate that Fe4Zn9, W-Zn solid solution and MoZn7 are formed on the Fe, W, and Mo interfaces. Theoretical calculations reveal that the adsorption energy of Na atom on Fe/Fe4Zn9 surpassed that on other current collectors, which indicates the superior charge-transfer kinetics of Na+ on the Fe electrode. The high performance of Fe current collector is attributed to the formation of a dense structure of Fe-Zn alloy and fast charge-transfer ability. Our study contributes to a deeper understanding of the intricate electrochemical processes at the negative electrode interface and provides a practical framework for optimizing the performance of Na‖Zn LMBs.

Enhanced electrocaloric response and energy storage in [(Bi0.5Na0.5)0.94Ba0.06]0.975Sr0.025TiO3 ceramic close to room temperature

Lead-free [(Bi0.5Na0.5)0.94Ba0.06]0.975Sr0.025TiO3 (BNBTS25), with morphotropic phase boundary, has attracted considerable attention due to its depolarization temperature, Td (Ferroelectric (FE)- Antiferroelectric (AFE) transition), which is in close proximity to room temperature (322K). Therefore, the research on electrocaloric and energy storage was limited to temperatures ranging from 223K to 363K. BNBTS25 presents firstly an intensive interests as promising candidate for environmental-friendly energy storage products. This material provides a good recoverable energy density up to Wrec = 577 mJ/cm3 with an energy-storage efficiency of η = 68% in the vicinity of Td. The origin of enhanced energy storage performance is discussed from a scientific point of view. Secondly, BNBTS25 exhibits a high electrocaloric effect (ECE), including an adiabatic temperature change of ΔT = 1.24 K and an electrocaloric responsivity of ξ = 0.301K.mm/kV was observed under an electric field of E = 40 kV/cm at a temperature near 290K. This high ECE performance exceeds that of several reported lead-free ceramics and even performs better than some lead based ceramics. The obtained results suggest that BNBTS25 ceramic is a promising candidate for both electrocaloric and energy storage applications in operating temperature such as cooling in microelectronic devices.

Fabrication of CNT-N@Manganese Oxide Hybrid Nanomaterials through a Versatile One-Pot Eco-Friendly Route toward Engineered Textile Supercapacitors.

The expansion of the Internet of Things market and the proliferation of wearable technologies have generated a significant demand for textile-based energy storage systems. This work reports the engineered design of hybrid electrode nanomaterials of N-doped carbon nanotubes (CNT-N) functionalized with two types of manganese oxides (MOs)-birnessite (MnO2) and hausmannite (Mn3O4)-and their application in solid-state textile-based hybrid supercapacitors (SCs). A versatile citric acid-mediated eco-friendly one-pot aqueous precipitation process is proposed for the fabrication of the hybrids. Remarkably, different types of MOs were obtained by simply changing the reaction temperature from room temperature to 100 °C, without any post-thermal treatment. Asymmetric textile SCs were developed using cotton fabrics coated with CNT-N and the hybrids as textile electrodes, and poly(vinyl) alcohol/orthophosphoric acid as the solid-gel electrolyte. The asymmetric devices presented enhanced energy storage performance relative to the symmetric device based on CNT-N and excellent cycling stability (>96%) after 8000 charge/discharge cycles owing to synergistic effects between CNT-N and the MOs, which endowed nonfaradaic and pseudocapacitive features to the SCs. The asymmetric SC based on CNT-N@MnO2 featured 47% higher energy density and comparable power density to the symmetric CNT-N-based device (8.70 W h cm-2 at 309.01 μW cm-2 vs. 5.93 W h cm-2 at 346.58 μW cm-2). The engineered hybrid CNT-N@MO nanomaterials and the eco-friendly citric acid-assisted one-pot precipitation route open promising prospects not only for energy storage, but also for (photo)(electro)catalysis, wastewater treatment, and (bio)sensing.

Enhanced energy storage performance of Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics by synergistic optimization strategies

Despite the fact that Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics have attracted widespread interest due to their various advantages, their lower recoverable energy storage density (Wrec) and energy storage efficiency (η) limit their development in pulsed power capacitors. In this work, we propose a synergistic optimization strategy to enhance the energy storage performance of 0.65Na0.5Bi0.5TiO3-0.35SrTiO3(NBST) based lead-free ceramics by introducing Bi0.8La0.2(Ni0.5Zr0.5)O3 (BLNZ) and employing viscous polymer process (VPP). The former converts the macroscopic domains into microscopic domains, limiting the polarization response hysteresis to give a large Pm–Pr. The latter reduces the thickness and porosity of the samples, resulting in a substantial increase in breakdown strength. Ultimately, by stepwise optimization of this strategy, the x = 0.15 ceramic by VPP (0.15VPP) achieves excellent energy storage performance (Wrec = 7.6 J/cm3, η = 92%) under 620 kV/cm and reliable temperature stability from 20-140 °C. The combined excellent results of this study show that our synergistic optimization strategy can effectively enhance the energy storage performance of NBT-based dielectric ceramics and could be further extended to other ceramic materials for pulsed power capacitors.

Construction of mesoporous Ni-Co-Mo oxide/sulfide composite composite nanosheet arrays as bifunctional material for charge storage and oxygen evolution reaction applications

At present, energy conversion and energy storage devices are gradually integrated together, which puts forward higher requirements for the design and construction of electrode materials. Herein, bi-functional Co-Mo oxides and Ni/Co sulfides (NCMOS) composite nanosheet arrays on Ni foam are constructed for supercapacitors and oxygen evolution reaction (OER) of water splitting. The Ni-Co-Mo nanosheet precursor is firstly synthesized by stepwise hydrothermal processes and then converted into Ni-Co sulfide and Co-Mo oxide by in-situ sulfurization. The nanoarray and in-situ sulfurization of active materials bring more reactive active sites, optimize reaction kinetics, and shorten the transport path of electrons and charges, which enhance energy storage performance and OER catalytic activity of NCMOS material. In terms of supercapacitor applications, NCMOS exhibits high specific capacity (1332.1 C g–1) and good cycle stability. For OER application, NiCMOS shows lower OER overpotential (290 mV at 100 mA cm–2), smaller Tafel slope (87.2 mV dec–1) and excellent catalytic stability in oxygen evolution for 60 h. The excellent charge storage and OER properties suggest that bi-functional oxide/sulfide composites have great potential in energy conversion and storage-integrated devices.

Engineering Phase Separation in Niobate Glass through Ab Initio Molecular Dynamics for Enhanced Energy Storage Performance and Unprecedented Thermal Stability in Niobate-Based Glass Ceramics.

The advancement of lead-free glass ceramics (GCs) possessing appropriate energy storage characteristics is crucial for the renewable energy and electronics industry. In this study, we synthesized lead-free GCs predominantly composed of the tungsten bronze phase, Ba3.3Nb10O28.3. Ab initio molecular dynamics initially reveal nonuniform distribution within the Ba/Nb-O regions in niobite glassy melts, offering valuable insights for the subsequent crystallization process. The proposal of a B-site engineering strategy is suggested, which entails the concurrent reduction of grain size and augmentation of the band gap in tungsten bronze GCs doped with Ta. This approach results in a substantial enhancement of the dielectric breakdown strength (BDS). Phase-field simulations have indicated that the refinement of grain sizes plays a pivotal role in augmenting the local electric field distribution and breakdown path, thereby contributing to the enhancement of BDS. As a consequence of these modifications, a notably high recoverable energy density (Wrec) of 5.23 J/cm3 can be achieved, accompanied by an ultrahigh efficiency (η) of 94%, and superior thermal stability in energy storage. These outcomes are particularly evident in the case of 2 mol % Ta2O5-doped P2O5-K2O-BaO-Bi2O3-TeO2-Nb2O5 (PKBBTN-T) GCs, where the Wrec and η can be determined to be 2.87 ± 3% J/cm3 and 95.46 ± 4%, respectively, over a temperature range spanning from 20 to 150 °C. Additionally, this specimen exhibits an exceptionally high discharge energy density (Wdis) of 4.01 J/cm3. This comprehensive investigation, comprising experimental and theoretical analyses, establishes an effective pathway and paradigm for the development of dielectric materials with ultrahigh energy storage properties.

Heterostructure Engineering of NiCo-LDHs for Enhanced Energy Storage Performance in Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are considered a promising device for next-generation energy storage due to their high safety and low cost. However, developing high-performance cathodes that can be matched with zinc metal anodes remains a challenge in unlocking the full potential of AZIBs. In this study, a typical transition metal layered double hydroxides (NiCo-LDHs) can be in situ reconstructed to NiCo-LDHs/Ni(Co)OOH heterostructure using an electrochemical cycling activation (ECA) method, serving as a novel cathode material for AZIBs. The optimized ECA-NiCo-LDHs cathode demonstrates a high capacity of 181.5 mAh g-1 at 1 A g-1 and retains 75% of initial capacity after 700 cycles at 5 A g-1 . The abundant heterointerfaces of the NiCo-LDHs/Ni(Co)OOH material can activate additional active sites for zinc-ion storage and accelerate ion diffusion. Theoretical calculations also suggest the heterostructure can boost charge transfer and regulate ion-adsorption capability, thereby improving the electrochemical performance. Additionally, the flexible AZIBs device exhibits good service performance. This study on interface engineering introduces a new possibility for utilizing LDHs in AZIBs and offers a novel strategy for designing electrode materials.

Enhanced energy storage performance of (Bi0·4Ba0·2K0·2Na0.2)TiO3–NaNbO3 high-entropy ceramics under moderate electric fields

High-entropy perovskite oxides (HEPOs) have attracted considerable attention as dielectric ceramics. However, the energy-storage performance of these HEPOs still requires improvement. In this study, a series of (1-x)(Bi0.4Ba0.2K0.2Na0.2)TiO3-xNaNbO3 high-entropy ceramics were designed and prepared using a high-entropy strategy. The introduction of antiferroelectric NaNbO3 into the (Bi0.4Ba0.2K0.2Na0.2)TiO3 medium-entropy matrix increased the configurational entropy and cationic disorder, resulting in improved energy storage performance. The ceramic with an optimal composition of 0.775(Bi0.4Ba0.2K0.2Na0.2)TiO3-0.225NaNbO3 achieved a high recoverable energy density (Wrec) of 2.523 J/cm3 and a high efficiency (η) of 83.7% at an electric field of 220 kV/cm. Furthermore, the material demonstrated good temperature and frequency stability, as well as good anti-fatigue properties. This paper presents a dielectric ceramic suitable for energy storage under low to moderate electric fields.

Enhanced energy storage performance of silver niobate-based antiferroelectric ceramics by two-step sintering mothed

Enhanced energy storage performance of silver niobate-based antiferroelectric ceramics by two-step sintering mothed

Phase-controlled preparation of cubic facet zeolitic imidazole framework-8-derived carbon using supercritical-CO2 medium: A solitary carbon material for symmetric supercapacitor

The preparation of nitrogen-rich carbon from zeolitic imidazole framework-8 (ZIF-8-C) has inspired considerable attention as electrode materials for advanced energy storage applications. Various dopants and composites have been employed to enhance energy storage performance; nevertheless, these approaches often entail high materials costs and expensive preparation methods. In the pursuit of more efficient ZIF-8-C electrodes, this study introduces a fresh preparation avenue using a supercritical-CO2 method (SC-ZIF-8-C) without any additives/surfactants. A comparison study is employed using the conventional method (C-ZIF-8-C). The prepared materials are examined through physical characterization to elucidate their phase purity, surface morphology, and functionalities. The electrochemical performance of the supercapacitor application is assessed using standard electro-analytical techniques. The SC-ZIF-8-C electrode possessed a low charge transfer resistance of 2.51 Ω and a high specific capacitance of 292.15 F/g at 0.75 A/g. In addition, the SC-ZIF-8-C is constructed as a symmetric sandwich-type device, which shows higher energy and power densities of 16.87 Wh/kg and 449.99 W/kg, respectively. The practical demonstration of a series-connection of devices remains capable of emitting a glow of light, even after 3 min. Thereby, the respectable performance of single carbon material and its eco-friendly synthesis approach establishes a route towards sustainable and green energy storage devices.

Programming Polarity Heterogeneity of Energy Storage Dielectrics by Bidirectional Intelligent Design.

Dielectric capacitors, characterized by ultra-high power densities, are considered as fundamental energy storage components in electronic and electrical systems. However, synergistically improving energy densities and efficiencies remains a daunting challenge. Understanding the role of polarityheterogeneity at the nanoscale in determining polarization response is crucial to the domain engineering of high-performance dielectrics. Here, a bidirectional design with phase-field simulation and machine learning is performed to forward reveal the structure-property relationship and reversely optimize polarity heterogeneity to improve energy storage performance. Taking BiFeO3-based dielectrics as typical systems, this work establishes the mapping diagrams of energy density and efficiency dependence on the volume fraction, size and configuration of polar regions. Assisted by CatBoost and Wolf Pack algorithms, this work analyzes the contributions of geometric factors and intrinsic features and find that nanopillar-like polar regions show great potential in achieving both high polarization intensity and fast dipole switching. Finally, a maximal energy density of 188 J cm-3 with efficiency above 95% at 8 MV cm-1 is obtained in BiFeO3-Al2O3 systems. This work provides a general method to study the influence of local polar heterogeneity on polarization behaviors and proposes effective strategies to enhance energy storage performance by tuning polarity heterogeneity.

Enhanced energy storage performance of 0.9NaNbO3–0.1Ba(Mg1/3Ta2/3)O3 ceramics by doping linear perovskite materials

In order to meet the production requirements of high performance lead-free dielectric capacitor, the linear material CaTiO3 (CT) was introduced into 0.9NaNbO3−0.1Ba(Mg1/3Ta2/3)O3 ceramics. The energy storage performance and structural mechanism of (1-x)[0.9NaNbO3−0.1Ba(Mg1/3Ta2/3)O3]–xCaTiO3(x = 0.05, 0.10, 0.15, and 0.20) ceramics were studied. Dense ceramics with high bulk density were prepared by traditional solid-state sintering method, and high recoverable energy density Wrec ∼ 5.84 J/cm3 and high energy storage efficiency η ∼ 85.4 % were obtained at x = 0.15. In this study, the Wrec and η of 0.9NN–0.1BMT ceramics were improved by introducing a linear material CT to increase the maximum polarization Pm (29 μC/cm2) and suppress the early nonlinear polarization saturation, and a large breakdown strength Eb (520 kV/cm) was obtained by optimizing the domain structure. In addition, under the applied electric field of 20 kV/mm, it has ultra-fast discharge speed t0.9 (28.9 ns), large discharge energy density Wd (1.02 J/cm3), ultra-high current density CD (863.4 A/cm2), and high-power density PD (86.34 MW/cm3). The above shows that NaNbO3-based relaxor ferroelectric ceramics are expected to be used in high-power electronic devices.