Fast Charge-discharge Capability Research Articles

Remarkable energy storage performance of BiFeO3-based high-entropy lead-free ceramics and multilayers

Electrostatic energy storage capacitors featuring fast charge–discharge capability play an indispensable role in pulsed power capacitors. However, the inverse correlation between polarization and dielectric breakdown strength (Eb) is the main obstacle limiting the access to high recoverable energy storage density (Wrec) and high efficiency (η). In this work, we designed a series of novel (1-x)BiFeO3-x(Ba0.2Sr0.2Ca0.2Bi0.2Na0.2)TiO3 (BF-xBSCBNT, x = 0.4–1.0) high-entropy lead-free relaxor ferroelectric ceramics. The synergy of refined grain size, broadened band gap, and core–shell microstructure is well-investigated by experimental results and phase-field simulations. High polarization difference is achieved by the strengthened relaxation behavior and the dominated polar nanoregions (PNRs). Both high Wrec of 6.0 J/cm3 and η of 81.1 % are achieved in the BF–0.8BSCBNT ceramics. In particular, a remarkable Wrec of 12.1 J/cm3 with a η of 86.1 % are obtained in the multilayer ceramic capacitors (MLCCs) fabricated from the x = 0.8 composition. Excellent temperature stability (<4.0 % in the range of 25–140 °C) and frequency stability (<6.2 % in the range of 1–500 Hz) are also achieved in MLCCs. The excellent energy storage performance demonstrates that high-entropy strategy is effective to develop novel lead-fee ceramics and devices for energy storage applications.

Research on the energy storage performance of laminated composites based on multidimensional co-design in a broad temperature range.

Polymer dielectrics play an irreplaceable role in electronic power systems because of their high power density and fast charge-discharge capability, but it is limited by their low stability in the temperature range of 25-200 °C. Rather than the introduction of one-dimensional fillers in polymers, we used a kind of multidimensional synergistic design to prepare Al2O3-TiO2-Al2O3/PI composites with layered structures by introducing multi-dimensional materials in polyimide (PI). In fact, the composite achieves much higher temperature stability than the pure PI film. The optimally proportioned composite has an energy density of 3.41 J cm-3 (vs. 1.48 J cm-3 for pure PI) even at 200 °C. Additionally, it reaches an impressive energy density retention of up to 90% and maintains an energy efficiency as high as 86% at 400 MV m-1 in the temperature range of 25-200 °C. The multidimensional coordination design is proposed to obtain composite films, and provides a feasible strategy in the study of polymer-based composites with high-temperature performance.

Numerical investigation of battery thermal management by using helical fin and composite phase change material

Li-ion batteries have become an indispensable part of modern life thanks to their portability, energy density, fast charge-discharge capability and various application areas. The thermal performance of the PCM promising method for battery thermal management systems (BTMS) is limited due to weak thermal conductivity property. The aim of this study is to investigate the contribution to the performance of BTMS by using innovative helical fins to improve the heat transfer performance of PCM due to its low thermal conductivity. Besides, the study includes composite phase change material (CPCM) due to advantages in practice such as form stability, mechanical behavior and higher thermal conductivity compared to PCM. In this scope, a hybrid system including helical fin and CPCM, paraffin-based expanded graphite (EG), is numerically investigated to ensure thermal control of a Li-ion battery in this study. Results shows that safe operating time is prolonged by increasing the widths and the number of rounds of the helical fin. However, the contribution of the EG fractions on the BTMS is ordered as an EG fraction of 12 % > 6 % > 20 % > 0 % due to a balance between the thermal conductivity and the latent heat property. The longest safe operating time is obtained by using Fin_W6-NR3 for EG fraction of 12 % in the CPCM as 9316 s corresponding to 244.0 % higher than the case of EG = 0 % and no fin used.

MXenes-based Multifunctional Nanomaterials for Lithium-ion Batteries: Opportunities and Challenges

Abstract: MXene-based multicomponent materials are 2D substances derived from transition metal (M) with carbide/nitride combinations having several propitious uses, including application in energy storage devices for high-performance electrodes for Lithium-ion batteries (LIBs) fabrication. The suitability of these new classes of materials for LIB electrodes can be attributed to their high conductivity combined with their excellent surface properties desirable for electrode applications, such as fast charge-discharge capability, high storage capacity and high rate capacity. However, there are several challenges possessed by MXene-based nanomaterials in the application of their electrodes in future flexible and wearable devices, demanding more research work and development strategies. After a brief overview of MXenes used in batteries, this paper deals with the synthesis, morphology-properties correlations, and their performance. Finally, this paper headlines the advantages, limitations, and challenges of MXene-based electrodes for LIBs, ending with concluding remarks.

High-Performance K Metal Batteries Enabled by Regulating an Electrolyte Solvation Structure

Batteries using a potassium metal (K-metal) anode are attention to a new type of low-cost and high-energy storage devices. However, the thermodynamic instability of the K-metal anode in organic electrolyte solutions causes uncontrolled growth of dendrites and parasitic reactions, which leads rapid capacity loss and low Coulombic efficiency.[1-4] In this presentation, I will introduce the advanced electrolyte using dual-salt for regulated solvation chemistry showing an improved the K-metal anode stability. Experimental and theoretical studies supported the details of solvation chemistry and results. Incorporating dual-salt into the electrolyte solution decreased the number of free solvent molecules surrounding the K+ leading to facile K+ desolvation as well as lowering the exchange current density improving the uniform K electrodeposition. Moreover, the modified electrolyte mitigates decomposition of the solvent molecules and leads to form enhanced mechanical rigidity of the SEI layer on the surface of the K–metal electrode with larger fraction of KF compound. Compared to previous studies, the K-metal anode using modified electrolyte shows long cycling stability at fast charge-discharge capability in symmetrical K | K cells. Even under high current density, the modified electrolyte ensures high areal capacity and an unprecedented lifespan with stable Coulombic efficiency for the K-metal full battery employing a sulfurized polyacrylonitrile cathode. M. Park, Y. Jeong, M. H. Alfaruqi, Y. Liu, X. Xu, S. Xiong, M.–G. Jung, H.–G. Jung, J. Kim, J.–Y. Hwang, Y.–K. Sun. Stable Solid Electrolyte Interphase for Long–Life Potassium Metal Batteries, ACS Energy Lett. 7 (2022) 401–409.Kim, W. Song, D.–Y. Son, L. K. One, Y. Qi. Lithium–Ion Batteries: Outlook on Present, Future, and Hybridized Technologies. J. Mater. Chem. A 7 (2019) 2942–2964.–H. Kim, G.–T. Park, B.–K. Son, G. W. Nam, J. Liu, L.–Y. Kuo, P. Kaghazchi, C. S. Yoon, Y.–K. Sun. Heuristic Solution for Achieving Long–Term Cycle Stability for Ni–Rich Layered Cathodes at Full Depth of Discharge, Nat. Energy 5 (2020) 860.–Y. Hwang, S.–T. Myung, Y.–K. Sun. Recent Progress in Rechargeable Potassim Batteries, Adv. Funct. Mater. 28 (2018) 1802938.

Improvement of fatigue endurance through modulating strain response in BaTiO3–Ca3Ti2O7 composite ceramics

Ferroelectric ceramics are highly desired for applications in energy storage devices due to their fast charge-discharge capability. However, electric field-driven gradual degradation of ferroelectric polarization (i.e., fatigue) inevitably results in a decrease in energy efficiency and energy storage density. Therefore, improving fatigue endurance is one challenge for their practical applications in energy storage devices. Here, we provide a strategy to modulate the strain response to the external electric field, and thus, increase the fatigue endurance by employing hybrid improper ferroelectricc Ca3Ti2O7 ceramic that exhibits a negative piezoelectric effect. We synthesized [Formula: see text] BaTiO[Formula: see text] Ca3Ti2O7 (BT-xCT) ceramics, in which the strain response of ceramics to the electric field gradually decreases with the increasing proportion of Ca3Ti2O7. For BT-0.3CT ceramic, the energy density storage efficiency is improved to 74.95% which is much higher than that of BT-0.1CT (48.07%). The strain response to the external electric field of BT-0.3CT is substantially lowered and almost reaches zero, leading to excellent fatigue endurance ability. This research work paves a route for designing ferroelectric ceramics with smaller strain response and enhanced fatigue endurance ability, which is expected to benefit a wide range of applications of ferroelectric ceramics in various electric capacitors and electric storage devices.

Long cycle life and high rate aqueous zinc-ion batteries enabled by polypyrrole bridging ammonium vanadium bronze nanosheet cathodes

Aqueous zinc-ion batteries are considered promising large grid energy storage systems because of their low cost and high safety. However, the limited cycle life associated capacity fading in cathode materials, especially at high charge-discharge rates, hampers the practical applications of aqueous zinc-ion batteries. Here we report that ammonium vanadium bronze nanosheets bridged by polypyrrole (NVO@PPy) as cathodes significantly enhance the cycle life and rate performances of aqueous zinc-ion batteries. At a high charge-discharge rate of 28 C (10 A g−1), the discharge capacity gradually increases with the number of cycles and reaches the maximum value of 195 mAh g−1 over 290 cycles, and the reversible capacity maintains 58% (108.8 mAh g−1) even after 2000 cycles. The fast charging-discharging and stable cycling performances are attributed to the high electronic/ionic conductivity of NVO@PPy and the stabilizing effect of PPy on interlayer ammonium. The zinc ion storage mechanism of the NVO@PPy is jointly contributed by intercalation/deintercalation and pseudocapacitance behaviour, the latter not only provides extra capacity but also facilitates fast charge-discharge capability.

Nano supercapacitors with practical application in aerospace technology: Vibration and wave propagation analysis

Recently, corrugated nanostructures have been intensely attractive among researchers due to their high electrical conductance, fast charge-discharge capability, and modest energy densities. Hence, it can be used in the design of nano supercapacitors with practical applications in defense technology. In this article, wave propagation and vibration of a nano supercapacitor are studied based on mathematical modeling. The nano supercapacitor is made from corrugated graphene (CG) layer covered by nano piezoelectric face sheets for smart control of the structure. Size effects are considered based on the novel theory of two-phase local/nonlocal elasticity. Surface stresses are taken into account based on Gurtin-Murdoch theory and the nanostructure is located on Kerr viscoelastic foundation which includes two springs, two dampers, and one shear element. For modeling the structure mathematically, refined zigzag theory (RZT) is used. According to Hamilton's principle, the governing equations are gained. The final equations are solved by the exact solution of Discrete Fourier Transform (DFT) for obtaining the phase velocity, cut-off and escape frequencies. In this novel work, influences of nonlocal parameter and local phase fraction factor, core and face sheets thickness, surface stress, residual stress, and external voltage are investigated on the wave propagation and vibration of the nano supercapacitor. Numerical results show that by using the piezoelectric layers and applying a negative external voltage, the frequency and wave propagation of the nanostructure can be reduced.

All-Carbon Monolithic Composites from Carbon Foam and Hierarchical Porous Carbon for Energy Storage.

We designed high-volumetric-energy-density supercapacitors from monolithic composites composed of self-standing carbon foam (CF) as the conducting matrix and embedded hierarchically organized porous carbon (PICK) as the active material. Using multiprobe scanning tunneling microscopy at selected areas, we were able to disentangle morphology-dependent contributions of the heterogeneous composite to the overall conductivity. Adding PICK is found to enhance the conductivity of the monoliths by providing additional links for the CF network, enabling high and stable performance. The resulting all-carbon CF-PICK composites were used as self-standing electrodes for symmetric supercapacitors without the need for a binder, additional conducting additive, metals as a current collector, or casting/drying steps. Supercapacitors achieved a capacitance of 181 F g-1 based on the entire mass of the monolithic electrode as well as an outstanding rate capability. Our symmetrical supercapacitors also delivered a record volumetric energy density of 19.4 mW h cm-3 when using aqueous electrolytes. Excellent cycling stability with almost quantitative retention of capacitance was found after 10,000 cycles in 6.0 M KOH as the electrolyte. Furthermore, charge-discharge testing at different currents demonstrated the fast charge-discharge capability of this material system that meets the requirements for practical applications.

Breakdown strength and energy density enhancement in polymer-ceramic nanocomposites: Role of particle size distribution

Polymer-ceramic nanocomposites play a very promising role for energy-storage in high power electronics and advanced pulsed power systems, due to their extremely fast charge-discharge capability. The low energy density is the key factor hindering their application, for which large endeavors have been made in the modulation of the fraction, morphology, size, and dispersion of the particle fillers but small in that of the size distribution, which is critical for energy-storage performance. We first investigated the role of this based on simulated nanocomposites with controlled lognormal distributions via a generation algorithm devised in this work. Dielectric response, breakdown behavior and energy-storage performance were explored for distributions with different standard deviations (SD) and mean values (MV), which were solved with the energy equivalence basis and a phase-field dielectric breakdown model. With the decrease of SD and MV, the effective permittivity declines slightly with enhanced permittivity change, which was related with the enhanced local electric field with intensified fluctuation and should be originated from the major contribution of the polymer matrix from the local energy perspective; whereas improved nominal breakdown strength was achieved owing to the weakened local maximum electric field, which leads to distinctly increased nominal energy density despite the slight decline of the permittivity. Keeping the fillers within a narrow disperse outperforms employing super fine particles. This work demonstrates that enhancement in breakdown strength and energy density can be attained via particle size distribution modulation, paving a new way for the further improvement of the energy-storage performance of polymer-ceramic nanocomposites.

Effect of Ca2+/Hf4+ modification at A/B sites on energy-storage density of Bi0.47Na0.47Ba0.06TiO3 ceramics

• By incorporating CaHfO 3 , the E b is greatly enhanced from 120 kV/cm for BNBT to 280 kV/cm for BNBT-12CH. • BNBT-12CH ceramic achieves a large recoverable energy-storage density of 4.2 J/cm 3 . • The η and W rec of BNBT-12CH ceramic gradually improve with increasing temperature from 25 °C to 140 °C. Pb-free relaxor ferroelectric materials are attractive because of their fast charge–discharge capability and environmental safety. Here, a series of new-type Pb-free ferroelectric ceramics are designed and fabricated: (1 - x )Bi 0.47 Na 0.47 Ba 0.06 TiO 3 - x CaHfO 3 (abbreviated as BNBT- 100x CH). Through the modification of Ca 2+ /Hf 4+ at A/B sites, a wider optical band gap and submicron grains are obtained, and the polar nano regions are induced in the structure. Therefore, an optimal W rec of 4.2 J/cm 3 is obtained for the BNBT-12CH ceramic under 280 kV/cm. In addition, the BNBT-12CH ceramic displays better energy-storage characteristics at high temperatures within the test range of 25–140 °C. All of these features indicate that the modification of BNT-based ceramics by Ca 2+ /Hf 4+ has a significant effect on energy-storage density. This work also offers a novel guidance for the development and application of Hf element.

Pomegranate-like Ti-doped LiNi0.4Mn1.6O4 5 V-class cathode with superior high-voltage cycle and rate performance for Li-ion batteries

The high-voltage and low-cost lithium nickel manganese oxides are regarded as the most potential cathode materials for high-density Li-ion batteries (LIBs), but the inferior ionic conductivity and vulnerable lattice oxygen limit their rate and cycle capabilities. Herein, we report a unique pomegranate-like Ti-doped LiNi0.4Mn1.6O4 cathode materials (LNMTO) without surface residues, which are expected to greatly shorten the Li+ transfer distance, enhance reaction kinetics and reduce the electrochemical polarization. Meantime, the strong Ti-O bonds can robust the lattice oxygen and stabilize the crystal structure during electrochemical reactions process. Consequently, the LNMTO exhibits a fast charge–discharge capability with a high reversible capacity of 101 mAh g−1 within 3.5–5.0 V even at 10C with an 84.4% capacity retention after 500 cycles at 1C, which is superior to the reported LiNi0.4Mn1.6O4-related cathode materials. This work provides a novel inspiration to design and synthesize high-voltage cobalt-free based cathode materials with satisfied lithium storage performances.

Enhanced Supercapacitive Performance of Higher-Ordered 3D-Hierarchical Structures of Hydrothermally Obtained ZnCo2O4 for Energy Storage Devices.

The demand for eco-friendly renewable energy resources as energy storage and management devices is increased due to their high-power density and fast charge/discharge capacity. Recently, supercapacitors have fascinated due to their fast charge–discharge capability and high-power density along with safety. Herein, the authors present the synthesis of 3D-hierarchical peony-like ZnCo2O4 structures with 2D-nanoflakes by a hydrothermal method using polyvinylpyrrolidone. The reaction time was modified to obtain two samples (ZCO-6h and ZCO-12h) and the rest of the synthesis conditions were the same. The synthesized structures were systematically studied through various techniques: their crystalline characteristics were studied through XRD analysis, their morphologies were inspected through SEM and TEM, and the elemental distribution and oxidation states were studied by X-ray photoelectron spectroscopy (XPS). ZCO-12h sample has a larger surface area (55.40 m2·g−1) and pore size (24.69 nm) than ZCO-6h, enabling high-speed transport of ions and electrons. The ZCO-12h electrode showed a high-specific capacitance of 421.05 F·g−1 (31.52 C·g−1) at 1 A·g−1 and excellent cycle performance as measured by electrochemical analysis. Moreover, the morphologic characteristics of the prepared hierarchical materials contributed significantly to the improvement of specific capacitance. The excellent capacitive outcomes recommend the 3D-ZnCo2O4 hierarchical peony-like structures composed of 2D-nanoflakes as promising materials for supercapacitors with high-performance.

Ultrahigh energy storage performance and fast charge-discharge capability in Dy- modified SrTiO3 linear ceramics with high optical transmissivity by defect and interface engineering

The excellent energy storage and pulse charge-discharge performance ceramics with high temperature stability and optical transmissivity are competitive for the development of electronic devices. In this work, comprehensive improved performances are simultaneously realized in DyxSr1-xTiO3 (DST) ceramics through defect and interface engineering. Meanwhile, increased high insulation grain boundary and reduced carrier mobility promote the increase of grain boundary resistance, and the increase of grain resistance primarily originates from the fact that DyTi' can easily attract oxygen vacancy, forming defect dipoles and restraining the movement of oxygen vacancies. Additionally, the relative density of ceramics is increased by sintering in O2 and doping Dy ions. Hence, x = 0.008 ceramics exhibit high coverable energy storage density of 4.00 J/cm3, high energy storage efficiency of 89.49%, excellent frequency (1Hz-1 kHz) and temperature stability (20-120 °C) and transmittance of >60% are achieved at 510 kV/cm at 0.2 mm. Furthermore, x = 0.008 ceramics possess the prominent current density of 420.1 A/cm2 and the prominent power density of 19.2 MW/cm3. Meanwhile, the short discharge rate of 20 ns and excellent stability of temperature (20-120 °C) are also achieved, suggesting that it is one candidate with strong potential for the application of lead-free high power capacitors.

High performance lithium-ion capacitors based on LiNbO3-arched 3D graphene aerogel anode and BCNNT cathode with enhanced kinetics match

High energy density remains difficult to achieve using current lithium ion capacitors (LICs) because of the mismatch of kinetics between the capacitor-type cathode and battery-type anode. To enhance the kinetic match, a graphene aerogel (GA) supported LiNbO3 nanoparticles (LiNbO3@GA) 3D conductive network is configured as a novel anode as well as a boron carbonitride nanotube (BCNNT) as cathode for LICs. Kinetics analysis of LiNbO3@GA anode and BCNNT cathode are conducted to further investigate the cation/anion storage behavior. Benefiting from the high pseudocapacitive contribution of LiNbO3 and the appealing features of 3D conductive framework, the LiNbO3@GA anode demonstrates enhanced kinetic properties and high-rate pseudocapacitive behaviors. Anion storage from both surface-controlled pseudocapacitive reaction and diffusion-limited intercalation/ deintercalation reaction in BCNNT electrode enables the cathode to exhibit fast charge-discharge capability, which greatly reduces the kinetic mismatch between cathode and anode. The assembled LiNbO3@GA//BCNNT LIC delivers the maximum energy density of 148 Wh kg−1 at the power density of 200 W kg−1 with a desirable cycling stability (82% after 7000 cycles). This strategy exploits a new type of material and widens the path for pseudocapacitive advanced high-rate devices in energy storage area.

Combining high energy efficiency and fast charge-discharge capability in calcium strontium titanate-based linear dielectric ceramic for energy-storage

The high energy density and power density dielectric ceramics with wide frequency and temperature stability are competitive materials for pulse power capacitors. This research proposes an effective strategy for enhancing energy storage performance of Ca0.5Sr0.5TiO3 ceramics through the introduction of Sn4+ ion. This ion restrains grain growth, increases high insulating grain boundaries, and thus enhances the barrier height of grain boundaries, which are demonstrated in SEM micrographs and complex impedance. The Ca0.5Sr0.5Ti0.97Sn0.03O3 (SnCST3) ceramics possess high energy storage density of 2.06 J/cm3 and efficiency of 95% under breakdown strength of 330 kV/cm, which get benefit from wide band gap of 5.3 eV. While the exceptional stability with minimal fluctuation (<15%) in the wide frequency range of 1–1000 Hz and temperature range of 20–120 °C are also achieved in this system. Furthermore, the pulse discharge performance are performed to appraise practical applications of pulse power capacitors. The prominent power density of 32.2 MW/cm3 and current density of 537.4 A/cm2 are obtained. Meanwhile, stored energy are released in very short duration of 13 ns as well as outstanding temperature stability is realized in the temperature range of 20–120 °C for the SnCST3 ceramic, confirming it as one competitor for lead-free high power capacitors.

Nano/Microstructured Silicon-Carbon Hybrid Composite Particles Fabricated with Corn Starch Biowaste as Anode Materials for Li-Ion Batteries.

Silicon has a great potential as an alternative to graphite which is currently used commercially as an anode material in lithium-ion batteries (LIBs) because of its exceptional capacity and reasonable working potential. Herein, a low-cost and scalable approach is proposed for the production of high-performance silicon-carbon (Si-C) hybrid composite anodes for high-energy LIBs. The Si-C composite material is synthesized using a scalable microemulsion method by selecting silicon nanoparticles, using low-cost corn starch as a biomass precursor and finally conducting heat treatment under C3H6 gas. This produces a unique nano/microstructured Si-C hybrid composite comprised of silicon nanoparticles embedded in micron-sized amorphous carbon balls derived from corn starch that is capsuled by thin graphitic carbon layer. Such a dual carbon matrix tightly surrounds the silicon nanoparticles that provides high electronic conductivity and significantly decreases the absolute stress/strain of the material during multiple lithiation-delithiation processes. The Si-C hybrid composite anode demonstrates a high capacity of 1800 mAh g-1, outstanding cycling stability with capacity retention of 80% over 500 cycles, and fast charge-discharge capability of 12 min. Moreover, the Si-C composite anode exhibits good acceptability in practical LIBs assembled with commercial Li[Ni0.6Co0.2Mn0.2]O2 and Li[Ni0.80Co0.15Al0.05]O2 cathodes.

Surface-functionalized Fe2O3 nanowire arrays with enhanced pseudocapacitive performance as novel anode materials for high-energy-density fiber-shaped asymmetric supercapacitors

Fiber-shaped asymmetric supercapacitors (FASCs) have potential applications in next-generation wearable and portable electronics due to their high power density, remarkable flexibility, fast charge-discharge capability, long cycle life and light weight. However, low specific capacitance and energy density hinder their practical applications. To obtain anode materials with high conductivity and high specific capacity, we first synthesize Fe2O3 nanowire arrays (NWAs) on carbon nanotube fibers as negative electrodes and then obtain FeS2 and FeP NWAs negative electrodes by sulfuration and phosphorization, respectively. The transformation processes effectively enhance the desirable properties of the electrode materials, improving the areal capacitance from 292 mF cm−2 to 833 mF cm−2 (sulfuration) and 1135 mF cm−2 (phosphorization) at a current density of 1 mA cm−2, demonstrating a significant improvement compared to Fe2O3 NWAs and, importantly, that phosphorization produces better results than sulfuration. Furthermore, the fabricated FASC exhibits outstanding mechanical flexibility and weavability and thus has great potential in for practical application in novel wearable and portable supercapacitors, which are expected to be the next generation of flexible energy-storage devices.

Enhanced energy storage and fast charge-discharge capability in Ca0.5Sr0.5TiO3-based linear dielectric ceramic

Ca0.5Sr0.5(TaxTi1-1.25x)O3-2 wt%SiO2 ceramic samples were fabricated by solid state method. XRD data showed all samples are assigned to perovskite structure, dense microstructure and relatively large grain size were displayed by SEM. Moreover, the effect of Ta5+ ion doping on increased resistivity and energy barrier height were analysed by impendance spectra. Exceptional energy storage performances which are 2 J/cm3 in energy density and 96% in energy efficiency under breakdown strength of 360 kV/cm can be obtained in the sample with x = 0.024, also possessing over 80% efficiency in a wide range of temperature (20–120 °C). Additionally, pulsed charging and discharging tests were carried out aiming to evaluate the practical performance of ceramic materials. The prominent parameters Imax of 32.2 A, CD of 256.1 A/cm2, PD of 15.4 MW/cm3 and outstanding temperature stability (20–120 °C) were achieved in the sample with x = 0.024 as well, releasing stored energy sharply (t0.9 < 25 ns). These properties verified this lead-free linear dielectric ceramic can be promising candidate for wider applications in the fields of energy-storage and charge-discharge.

Novel lead-free ceramic capacitors with high energy density and fast discharge performance

Dielectric capacitors with high energy storage density, good frequency/temperature stability, and fast charge-discharge capability are highly demanded in pulsed power systems. In this work, we design and prepare a novel lead-free 0.88BaTiO3-0.12Bi(Li1/3Zr2/3)O3 (0.12BLZ) relaxor ferroelectric ceramic for dielectric capacitor application. The microstructure, conduction mechanism, dielectric properties, and energy storage behavior of the 0.12BLZ ceramic were systematically studied. The impedance analysis demonstrates that the introduction of BLZ enhances the insulation ability and breakdown strength of the 0.12BLZ ceramic. Meanwhile, the introduction of BLZ can also reduce the polarization nonlinearity of the BaTiO3 matrix due to the weakly coupled relaxor behavior. As a result, ultrahigh energy storage density (Urec) of 3 J/cm3 and efficiency (η) of 93.8% were simultaneously achieved in 0.12BLZ ceramic. The significantly improved Urec was far superior to most of the recently reported lead-free bulk ceramics. Additionally, excellent frequency and temperature stability (variations of Urec less than 15% in different frequencies (1–100 Hz) and temperatures (25–140 °C)) can be also observed. In addition, the 0.12BLZ ceramic presents an ultrahigh current density (Ddis) of 759 A/cm2, a giant power density (Pm) of 37.9 MW/cm3, and a fast discharge time of 80 ns. The pulsed charge-discharge performances of the 0.12BLZ ceramic are obviously better than those of other lead-free ceramics. These results indicate that the 0.12BLZ relaxor ferroelectric may be an excellent candidate material applied for pulsed power systems.