Dielectric,ferroelectric, and energy storage properties of Ba(Zn1/3Nb2/3)O3-modfied BiFeO3–BaTiO3 Pb-Free relaxor ferroelectric ceramics

Pb-free bulk ceramics (1-x)[0.65BiFeO₃-0.35BaTiO₃]-xBa(Zn_1/3Nb_2/3)O₃ were produced by traditional solid-state reaction route. In this experiment, Ba(Zn_1/3Nb_2/3)O₃ (BZN) was introduced to destroy long-range order domains in order to obtain higher energy storage performance. Impedance and XPS analysis indicate that oxygen vacancies exist and participate in relaxation processes at high temperatures. With the increase of BZN content, the dielectric relaxation behavior is improved, the hysteresis loop becomes thinner, remnant polarization decreases, and the breakdown electric field increases to 180 kV/cm in 15BZN. A maximum W_rec (1.62 J/cm³) is eventually reached in 7BZN with great temperature stability. The highest efficiency is 91% in 15BZN with W_rec of 1.28 J/cm³. Charge-discharge tests show that ceramics have a quick discharge time of t_0.9 < 0.1 μs, which makes BZN-doped ceramics a potential candidate for energy storage devices.     

Enhanced energy storage performances of Bi(Ni1/2Sb2/3)O3 added NaNbO3 relaxor ferroelectric ceramics

In the development of dielectric ceramic materials, the requirements of miniaturization and integration are becoming increasingly prominent. How to obtain greater capacitance in a smaller volume is one of the important pursuits. In this paper, lead-free (1-x)NaNbO₃-xBi(Ni_1/2Sb_2/3)O₃(xBNS) with high recoverable energy storage density (W_rec) and relatively high energy storage efficiency(η) were prepared by a solid state sintering method. Bi(Ni_1/2Sb_2/3)O₃ was introduced into the Sodium niobate ceramics(NN)-based ceramics to reduce the sintering temperature and increase the maximum breakdown field strength (E_b). Finally, 0.15BNS achieved a high E_b of 460 kV/cm, W_rec of 3.7 J/cm³ and η of 77%. In addition, the sample maintained excellent stability in the frequency range of 1–120 Hz. And the 0.15BNS ceramics also exhibited high power density (P_D = 36.4 MW/cm³), large current density (C_D = 520.8 A/cm²) and relatively fast charge-discharge rate (t_0.9 = 1050 ns). These results demonstrate the potential application value of xBNS ceramics in energy storage capacitors.     

Achieving outstanding temperature stability in KNN-based lead-free ceramics for energy storage behavior

Lead-free ceramics with prominent energy storage properties are identified as the most potential materials accessed in the dielectric capacitors. Nevertheless, high recoverable energy storage density (W_rec), large energy storage efficiency (η) and preferable temperature stability can hardly be met simultaneously. The Bi(Zn_2/3Ta_1/3)O₃ and NaNbO₃ components are doped in KNN ceramics to substantiate the reliability of this tactic. A high recoverable energy density (W_rec) of ～ 4.55 J/cm³ and a large energy storage efficiency (η) of ～ 87.8% are acquired under the dielectric breakdown strength (DBS) of ～ 375 kV/cm, along with a splendid thermal stability (W_rec variation: ～ 2.3%, η variation: ～ 4.9%) within the temperature range of 20 ℃? 120 ℃. This article demonstrates that the KNN-based ceramics integrate high energy storage properties and outstanding temperature stability at the same time, which broadens the application fields of pulse power systems.     

Energy storage properties in Bi(Mg1/2Sb2/3)O3-doped NaNbO3 lead-free ceramics

Sodium niobate energy storage ceramics with high energy density and efficiency can be used as potential candidate materials for pulse power devices. Doping modification of dielectric ceramic matrixes is an effective means to obtain high performance. The (1-x)NaNbO₃-xBi(Mg_1/2Sb_2/3)O₃ ceramics were designed in this work. And 0.85NaNbO₃-0.15Bi(Mg_1/2Sb_2/3)O₃ showed a large W_rec of 4.65 J/cm³ at an E_b of 580 kV/cm. Excellent frequency stability of W_rec (1.67–1.7 J/cm³) and η (86%–89.1%) over frequency range of 1–100Hz was observed. Further, good temperature stability of W_rec (1.5–1.71 J/cm³) and η (68%–87%) over abroad temperature range of 20–180 °C was attained successfully. In addition, excellent power density (P_D = 113 MW/cm³), large current density (C_D = 1255 A/cm²) and discharge speed (0.51μs) were obtained, which demonstrates the great potential practical value of this ceramic in the energy storage applications.     

Structure,dielectric properties of novel Ba(Zr,Ti)O3 based ceramics for energy storage application

(1-x) Ba(Zr_0.2Ti_0.8)O₃-x Na_0.5Bi_0.5TiO₃ (x = 0, 10, 20 30, 40, 50 mol%) (BZTN) ceramics are prepared by the traditional solid phase method. All BZTN ceramics exhibit a pseudo-cubic BZT based perovskite structure. Both the average grain size and the relaxor ferroelectricity of BZTN ceramics gradually increase with increasing NBT content. The W_rec of 3.22 J/cm³ and η of 91.2% is obtained for the BZTN40 ceramic at 241 kV/cm. BZTN40 ceramic also exhibits good temperature stability from room temperature to 150 °C and frequency stability from 1 Hz to 100 Hz. A P_D of 0.621 J/cm³ and a t_0.9 of 82 ns is obtained for the BZTN40 ceramic at 120 kV/cm. BZTN ceramics show application potential in energy storage and pulse power capacitors.     

Ultrahigh energy storage density in Ba0.85Ca0.15Zr0.1Ti0.9O3-based lead-free ceramics by introducing a relaxor end-member

Dielectric ceramics with relaxor characteristics are promising candidates to meet the demand for capacitors in next-generation pulse devices. In this work, Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT)-based lead-free ceramics with an ultrahigh recoverable energy storage density (W_rec) were designed and fabricated by introducing the relaxor end-member of Bi(Zn_2/3Ta_1/3)O₃ (BZT). The addition of BZT disrupted the ferroelectric (FE) long-range order and triggered an FE-to-relaxor FE (RFE) phase, leading to the formation of locally polar nano-regions (PNRs) and significantly inhibiting grain growth. Meanwhile, the presence of PNRs with good thermal stability improved the temperature stability of both the dielectric constant (ε') and W_rec. More importantly, the breakdown electric field strength was significantly improved up to ∼640 kV/cm, resulting in an ultrahigh W_rec of ∼7.11 J/cm³ for the 8%BZT doped BCZT (BCZT-BZT8) ceramic. Furthermore, the BCZT-BZT8 ceramic exhibited excellent charge/discharge performances (C_D ∼ 458.4 A/cm², P_D ∼ 50.4 MW/cm³, W_D ∼ 1.354 J/cm³, t_0.9 ∼ 320 ns) with good thermal stability in the temperature range of 298–373 K. The defect chemistry of the BCZT-BZT8 was explored using electron paramagnetic resonance (EPR) spectroscopy which revealed an EPR signal (g ∼ 1.955), associated with oxygen vacancies. The above findings indicate that the novel composition of BCZT-BZT8 has great prospects in energy storage capacitor applications.     

A new family of sodium niobate-based dielectrics for electrical energy storage applications

Although tremendous achievements have been made in enhancing recoverable energy storage density (W_rec) of lead-free dielectric ceramics for electrical energy storage applications in recent years, these ceramics with high W_rec still have two disadvantages: complex chemical composition and difficult preparation process. In this work, we selected NaNbO₃ (NN)-based ceramics as base materials and used Bi₂O₃ as a sintering aid to reduce porosity and enhance dielectric breakdown strengths. Encouragingly, high W_rec, simple chemical composition and facile preparation process were simultaneously realized in 0.77NaNbO₃-0.23BaTiO₃ (0.77NN-0.23BT) ceramics. A large W_rec of 1.5 J cm^?3 at 175 kV cm^?1 and excellent thermal stability (variation of W_rec < 15% over the temperature range of 20?140 °C) were simultaneously achieved in 0.77NN-0.23BT ceramics. More importantly, this work could bring out the development of a series of NN-based ceramics for electrical energy storage in the future such as NN-ABO₃ (A = Ca and Sr; B = Ti and Zr).     

Effect of Sr(Zn1/3Nb2/3)O3 modification on the energy storage performance of BaTiO3 ceramics

Lead-free (1-x)BaTiO₃-xSr(Zn_1/3Nb_2/3)O₃ (abbreviated as BT-xSZN, x = 0–0.08) relaxor ferroelectric ceramics were prepared using the traditional solid phase technology, and the effects of SZN modification on their phase structures, microstructures, dielectric performance, ferroelectricity and energy storage performance were studied in detail. A pure perovskite phase was observed in the BT-xSZN ceramics. The BT-based ceramics modified by SZN exhibited refined grain size. As the SZN content was increased, the breakdown strength initially increased and then decreased, and the ferroelectric loops gradually became ‘slim’. The BT-xSZN (x = 0.07) ceramics demonstrated a favourable energy storage performance with high recoverable energy density (W_rec = ~1.45 J/cm³) and energy storage efficiency (η = ~83.12%) at 260 kV/cm. Results indicate that the energy storage performance of BaTiO₃ ceramics modified by SZN can be remarkably improved, widening their applications in energy storage at low temperatures.     

High-energy storage density in NaNbO3-modified (Bi0.5Na0.5)TiO3-BiAlO3-based lead-free ceramics under low electric field

Ceramic-based dielectric capacitor are highly suitable for pulsed power applications due to their high power density and excellent reliability. However, the ultrahigh applied electric field limit their applications in integrated electronic devices. In this work, (1−x){0.96(Bi_0.5Na_0.5)(Ti_0.995Mn_0.005)O₃-0.04BiAlO₃}-xNaNbO₃ (BNT-BA-xNN, x = 0, 0.04, 0.08, 0.12, and 0.16) ternary ceramics were designed to achieve excellent energy storage properties. It was found that the introduction of NaNbO₃ (NN) effectively increase the difference (ΔP) between P_max and P_r, resulting in an obvious enhancement of the energy storage properties. High recoverable energy storage density, responsivity, and power density, that is, W_rec = 2.01 J/cm³, ξ = W_rec/E = 130.69 J/(kV⋅m²), and P_D = 25.59 MW/cm³, accompanied with superior temperature stability were realized at x = 0.14 composition. In addition, the thermal stable dielectric properties of the sample can be prominently improved with increasing NN content. The temperature coefficient of capacitance (TCC) of x = 0.16 composition is lower than 15% over the temperature range from 49°C to 340°C, with a high dielectric permittivity of 1647 and a low dielectric loss (0.0107) at 150°C. All these features show that the BNT-BA-xNN ceramics are promising materials for energy storage application.     

Energy storage and discharge performance for (1−x)BaSrTiO3−xBi(Zn1/2Ti1/2)O3 ceramics

Although lead-free dielectric ceramics have been widely studied to obtain excellent dielectric properties and good energy storage properties, the primary challenge of low energy storage density has not yet been resolved. Here, we introduce the concept of crossover relaxor ferroelectrics, which represent a state intermediate between normal ferroelectrics and relaxor ferroelectrics, as a solution to address the issue of low energy density. The (1−x)BaSrTiO₃−xBi(Zn_1/2Ti_1/2)O₃ (x = 0,.05, .1, .15, .2) ceramics were prepared by a solid-state method. Remarkably, 0.85BST–0.15BZT ceramics achieved a high recoverable energy density (W_rec) of 2.18 J/cm³ under an electric field of 240 kV/cm. BST–BZT materials exhibit substantial recoverable energy density, high breakdown strength, and superior energy efficiency, positioning them as a promising alternative to meet the diverse demands of high-power applications.     

Improved dielectric energy storage performance of Na0.5Bi0.5TiO3-based lead-free relaxation ferroelectric ceramics achieved by domain structural regulation and enhanced densification

There is still a problem of low energy storage density in dielectric capacitors which is a core component of power systems. For the improvement of the energy storage density, the linear dielectric material CaTiO₃ (CT) was introduced in Na_0.5Bi_0.5TiO₃ (NBT) ceramics in this paper. By modifying the A site, a new relaxor ferroelectric ceramic was successfully synthesized and attained a recoverable density (W_rec) of 2.34 J/cm³ at x = 0.18. Moreover, the preparation process was optimized in this paper. Through the viscous polymer process (VPP) route, the energy density (W_A) of 82NBT-18CT_VPP ceramic further reaches 6.45 J/cm³ at 340 kV/cm, with efficiency (η) up to 75% and a W_rec of 4.82 J/cm³. At the same time, the change of W_rec is small at temperature (30–150 °C) and frequency (1 Hz–300 Hz), which demonstrates its excellent stability. The discharge power density reaches about 180 MW/cm³ and the discharge time is 0.117 μs, which indicates its excellent pulse discharge performance. The results show that 82NBT-18CT lead-free relaxation ferroelectric material is expected to become ideal for high-energy storage applications.     

Relaxor antiferroelectric-like characteristic boosting enhanced energy storage performance in eco-friendly (Bi0.5Na0.5)TiO3-based ceramics

Ideal relaxor antiferroelectrics (RAFEs) have high field-induced polarization, low remnant polarization and very slim hysteresis, which can generate high recoverable energy storage W_rec and high energy storage efficiency η, thus attracting much attention for energy storage applications. True RAFEs, on the other hand, are extremely rare, and the majority of them contain environmentally hazardous lead. In this work, we use a viscous polymer rolling process to synthesize a novel and eco-friendly 0.65Bi_0.5Na_0.4K_0.1TiO₃-0.35[2/3SrTiO₃-1/3Bi(Mg_2/3Nb_1/3)O₃] (BNKT-ST-BMN) dielectric material, which possesses a very typical RAFE-like characteristic. As a result, this material has a high W_rec of 4.43 J/cm³ and a η of 86% at an electric felid of 290 kV/cm, as well as a high thermal stability of W_rec (>3 J/cm³) over a wide range of 30–140 °C at 250 kV/cm. Our findings suggest that the BNKT-ST-BMN material could be a potential candidate for use in energy storage pulse capacitors.     

Optimized energy storage performance in BF-BT-based lead-free ferroelectric ceramics with local compositional fluctuation

BiFeO₃-based lead-free ferroelectric is considered a potential candidate for energy storage applications owing to its high spontaneous polarization. To tackle the compromise between high polarization and energy storage density, NaNbO₃ (NN) was introduced into 0.7BiFeO₃-0.3Ba(Hf_0.05Ti_0.95)O₃ (BF-BHfT) ceramics, where Nb⁵⁺ ions enter the BF-BHfT lattices and enhance resistivity, while Na⁺ ions occupied on the A-sites and smash the long-range ferroelectric order into polar nanoregions. Consequently, the ceramics could maintain high maximum polarization and low remanent polarization. High recoverable energy density (W_rec) of 5.2 J/cm³ and efficiency (88%) were recorded in 0.53BF-0.3BHfT-0.17NN ceramics. Besides, it exhibited good thermostability up to 120 °C (W_rec variation < 5%), frequency stability from 10 to 200 Hz (W_rec variation < 7%) and excellent fatigue resistance after 10⁴ cycles (W_rec variation < 0.2%). Under different electric fields the efficiency still maintains nearly constant. In charge-discharge test a W_dis of 3.7 J/cm³ was recorded, which proved 0.5³BF-0.3BHfT-0.17NN ceramics a promising candidate for energy storage applications.     

(1-x)Bi0.5Na0.47Li0.03TiO3-xNaNbO3 lead-free ceramics with superior energy storage performances and good temperature stability

Dielectric capacitors show great potential in superior energy storage devices. However, the energy density of these capacitors is still inadequate to meet the requirement of energy storage applications. In this study, the Bi_0.5Na_0.47Li_0.03TiO₃-xNaNbO₃ (BNLT-xNN) ceramics were prepared via conventional solid-phase reaction. Results showed that NN can efficaciously enhance the breakdown strength (E_b) and the relaxation behavior of the BNLT ceramic because of the broken ferroelectric long-range order. When x = 0.3, the maximum E_b reached 350 kV/cm, at which the 0.7BNLT-0.3NN ceramic exhibited the high recoverable energy storage density (W_rec) of 4.83 J/cm³ and great efficiency (η) of 78.9%. The ceramic demonstrated good temperature stability at 20 °C-160 °C and excellent fatigue resistance. Additionally, the 0.7BNLT-0.3NN ceramic presented high power density (P_D; ～77.58 MW/cm³), large current density (C_D; ～861.99 A/cm²), and quite short discharge time (t_0.9; ～0.090 μs). These results indicated that the 0.7BNLT-0.3NN material has excellent energy storage properties and various application prospects.     

Enhanced energy storage properties of Bi(Ni2/3Nb1/6Ta1/6)O3–NaNbO3 solid solution lead-free ceramics

Sodium niobate energy storage ceramics with good environmental performance are widely used in electric power conversion and pulse power system, large energy storage density and high efficiency, huge power density and charge and discharge faster. In this work, (1-x)NaNbO₃-xBi(Ni_2/3Nb_1/6Ta_1/6)O₃ [(1-x)NN-xBNNT] (0.12 ≤ x ≤ 0.18) ceramics system were prepared by solid state reaction method. By introducing Bi(Ni_2/3Nb_1/6Ta_1/6)O₃ (BNNT), a relaxation strategy was constructed, which significantly improved the energy storage properties of NaNbO₃ (NN) based ceramics. Finally, comparatively high recoverable energy density (W_rec) of 3.43 J/cm³ and large energy storage efficiency (η) of 83.3% were obtained in 0.86NN-0.14BNNT ceramics. Besides discharge energy density (W_d) of 0.69 J/cm³, ultra fast charge-discharge rate (t_0.9) of 55 ns, the power density (P_D) of 70.66 MW/cm³ and the current density (C_D) of 883.23 A/cm² were also observed in ceramic.     

High energy storage performance in BaTiO3-based lead-free relaxors via multi-dimensional collaborative design

The application of advanced pulse power capacitors strongly depends on the fabrication of high-performance energy storage ceramics. However, the low recoverable energy storage density (W_rec) and energy efficiency (η) become the key links limiting the development of energy storage capacitors. In this work, a high W_rec of ～5.57 J cm^?3 and a large η of ～85.6% are simultaneously realized in BaTiO₃-based relaxor ceramics via multi-dimensional collaborative design, which are mainly attributed to the ferroelectric-relaxor transition, enhanced polarization, improved breakdown electric field, and delayed polarization saturation. Furthermore, the excellent temperature stability (ΔW_rec < ± 5%, 25–140 °C), frequency stability (ΔW_rec < ± 5%, 1–200 Hz), and outstanding charge/discharge performance (current density ～1583.3 A cm^?2, power density ～190.0 MW cm^?3) with good thermal stability are also achieved. It is encouraging that this work demonstrates that multi-dimensional collaborative design is a good strategy to develop new high-performance lead-free materials used in advanced dielectric capacitors.     

Enhanced energy storage performance of eco-friendly BNT-based relaxor ferroelectric ceramics via polarization mismatch-reestablishment and viscous polymer process

In this work, we synthesized a novel and eco-friendly relaxor ferroelectric system, i.e., (1?x)(0.8Bi_0.5Na_0.4K_0.1TiO₃-0.2SrTiO₃)-xNaNbO₃ (BS-xNN) ceramics with x = 0.1–0.4 based on a solid state reaction technique. The structural, microstructural, dielectric as well as ferroelectric characteristics of BS-xNN ceramics were comprehensively examined. According to our findings, the Ti–O coupling reduces as the NN content increases, while the Nb–O coupling strengthens, leading in a nano-scale polarization mismatch-reestablishment process that enhances energy storage performance. Because of the reduction in thickness and porosity, the viscous polymer process significantly increases the breakdown strength of ceramic samples. More crucially, at 260 kV/cm, 0.6BS-0.4NN ceramics have an ultrahigh recoverable energy storage density W_rec of 4.44 J/cm³ and a high energy storage efficiency η of 81.8%. Furthermore, thermal stability of energy storage performance is also identified across a wide temperature range of 30 °C from 140 °C at 215 kV/cm. The higher performance of energy storage not only indicates the feasibility of our technique, but also serves as a model for the manufacturing of high-quality dielectric ceramics with a wide range of industrial applications.     

(Bi0.5Na0.5)TiO3-based relaxor ferroelectrics with simultaneous high energy storage properties and remarkable charge-discharge performances under low working electric fields for dielectric capacitor applications

High energy storage and charge-discharge performances under low electric field are desirable for lead-free dielectric materials because of environmental hazards, the risk of high voltage and the high cost of insulation technology. Herein, lead-free ceramics based on 0.6BNT-0.4Sr_0.775Bi_0.15TiO₃ (BNT-SBT) were designed, which simultaneously achieves a large energy storage density (W_rec~ 2.41 J/cm³) and a high efficiency (η~87.5%) under a low electric field of 190 kV/cm due to enhanced dielectric properties and the relaxation response. Moreover, the energy storage properties of the BNT-SBT ceramic exhibit moderate temperature stability, excellent frequency dependence, and cycling reliability. Furthermore, the charge-discharge performance simultaneously features a high power density (P_D~51.4 MW/cm³), an ultrafast discharge speed (t_0.9–77 ns), and remarkable stability against temperature and cycling. This study exploits a high-efficiency BNT-related ceramics with concurrently high energy storage and charge-discharge performances under low electric fields, which provides great potential in practical dielectric capacitor applications.     

A novel relaxor (Bi,Na,Ba)(Ti,Zr)O3 lead-free ceramic with high energy storage performance

Energy storage ceramic capacitors advance in high power density and working voltage, but challenge in simultaneously large recoverable energy density (W_rec), high energy efficiency (η), and good thermal stability. To achieve this, a novel lead-free ceramic system (1-x)(Bi_0.5Na_0.5)TiO₃-x(BaZr_0.3Ti_0.7O₃) [(1-x)BNT-xBZT] was explored by tailoring the ferroelectric relaxor states. The introduction of BZT gradually promotes the transformation of ferroelectric states into relaxor states at around the room temperature for x = 0.3-0.5 that presents a pinched P-E loop. The optimized composition of x = 0.45 possesses a large W_rec of up to 2.6 J/cm³ and ultrahigh ƞ of 94%, with only a small variation (±8%) in W_rec and the high ƞ (90%) over a broad temperature range (−30°C to 180°C), demonstrating the superior performances compared to many existing lead-free ceramics. The remarkable advantages of the novel BNT-BZT lead-free ceramics explored in this study are thus promising for the high-efficiency and temperature-stable energy storage capacitor applications.     

Achieving ultrahigh energy storage performance in BiFeO3-BaTiO3 based lead free relaxors via a composition optimization strategy

The 0.63(1-x)Bi_1.02FeO₃-0.37BaTiO₃-xBi(Zn_2/3(Nb_0.85Ta_0.15)_1/3)O₃ (abbreviated BF-BT-xBZNT) high temperature dielectric ceramics were prepared via a two-step sintering (TTS) method. The appropriate medium permittivity achieved in the BF-BT-0.13BZNT ceramic is conducive to mitigating the polarization saturation and improving the breakdown field strength. The domain evolution behavior from piezoresponse force microscopy (PFM) reveals that the introduction of BZNT promotes the formation and switching of more nanodomains of BF-BT ceramics, facilitating the enhancement of energy storage efficiency. The excellent energy storage performance of total energy storage density (W_tot) of 6.06 J/cm³, recoverable energy storage density (W_rec) of 4.85 J/cm³ and a high energy storage efficiency (η) of 80% are simultaneously obtained under 410 kV/cm in the BF-BT-0.13BZNT ceramic. Meanwhile, the ceramic exhibits excellent thermal endurance (10–130 ℃), frequency (1–100 Hz) and fatigue (10⁵ cycles) stability. The current work provides a promising strategy for designing high-performance dielectric energy storage materials which operate in harsh environments.