Realizing high energy density and superior charge-discharge characteristics in NN-10BT-based ceramics

The low recoverable energy storage density (W_rec) of bulk ceramics has long limited their miniaturization and lightweight development. Here, we designed the (1-x)(0.90NaNbO₃-0.10BaTiO₃)-xNa_0.2Bi_0.4La_0.2TiO₃ (NN-10BT-xNBLT) ceramics. With the introduction of NBLT, the dielectric breakdown strength (BDS) of NN-10BT-based ceramics increased from 174.8 kV/cm to 289.1 kV/cm. A promising finding is that the NN-10BT-15NBLT ceramic has an ultrahigh energy storage density W of 3.42 J/cm³ and a large energy storage efficiency η of 78.9%, as well as excellent frequency and thermal stability. The NN-10BT-15NBLT ceramic, on the other hand, has an outstanding current density C_D of 1021.21 A/cm² together with a high power density P_D of 102.12 MW/cm³ at 200 kV/cm. Most importantly, the variation of charge-discharge properties (C_D and P_D) is only ?7.8% after 10⁴ cycles, suggesting that the capacitor has potential practical application significance.     

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.     

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.     

Simultaneously with large energy density and high efficiency achieved in NaNbO3-based relaxor ferroelectric ceramics

Dielectric capacitors are in urgent need of miniaturized and lightweight products. The new lead-free NaNbO₃-based ferroelectric ceramic material is a good choice owing to its high energy storage density, superior charge/discharge performance and decent frequency/temperature stability. In this work, a novel lead-free relaxor ferroelectric ceramic, (1-x)NaNbO₃-xBa(Mg_1/3Nb_2/3)O₃ [(1-x)NN-xBMN, x = 0.18, 0.20, 0.22 and 0.24], was designed and prepared via a local random field strategy. The impedance analysis demonstrates that the introduction of BMN could enhance the insulation ability and breakdown strength of the (1-x)NN-xBMN ceramic. Finally, the excellent energy storage performances with simultaneously ultrahigh energy storage density (W_st～4.04 J/cm³), recoverable energy storage density (W_rec～3.51 J/cm³), efficiency (η～87 %) and fatigue endurance (number of cycles: 5000) are obtained in the 0.78NN-0.22BMN ceramic. In addition, excellent frequency (1～100 Hz) and temperature stability (20～140 °C) can also be observed in the 0.78NN-0.22BMN ceramic. It is crucial that the ceramic shows extremely short charge-discharge time (t_0.9～45 ns), tremendous current density (C_D～680 A/cm²), giant power density (P_D～47.6 MW/cm³) and excellent temperature stability (30～150 °C). These results indicate that 0.78NN-0.22BMN ceramic is a promising dielectric capacitor material.     

Large energy density with excellent stability in fine-grained (Bi0.5Na0.5)TiO3-based lead-free ceramics

In this work, fine-grained (0.95-x)(Bi_0.5Na_0.5)TiO₃-0.05BaTiO₃-xBi(Zn_2/3Nb_1/3)O₃ (abbreviated as BNT-BT-xBZN, x = 0～0.20) lead-free ceramics are successfully prepared, showing a high energy storage performance. The addition of BZN results in decreased grain size, enhanced breakdown strength and stronger relaxor behavior with polar nanoregions. Slimmer P-E loops are thereby achieved, leading to the improvement of energy density and efficiency. As a result, a high W_D of ～2.83 J/cm³ is achieved under a relatively low electric field of 18 kV/mm in the x = 0.125 ceramic with submicron-sized grains (～0.4 μm). The W_D value is larger than that of x = 0 ceramic by ～800%. Furthermore, the x = 0.125 ceramic possesses excellent frequency stability and strong fatigue endurance. The BNT-BT-xBZN lead-free ceramics show promising potential for application in high energy density ceramic capacitors.     

Ultrahigh storage density achieved with (1-x)KNN-xBZN ceramics

A series of (1-x)K_0.5Na_0.5NbO₃-xBa(Zn_1/3Nb_2/3)O₃ ((1-x)KNN-xBZN) nanostructural ceramics was successfully synthesised via solid-state reactions. These nanostructural ceramics exhibited high energy storage density compared with pure KNN ceramics. Further analysis of their dielectric/ferroelectric properties and structures revealed that the addition of BZN alloy disrupted the long-range order of the ferroelectric lattice of pure KNN and favoured the formation of ferroelectric islands and/or polar nano-regions. Consequently, the nanostructured ceramic with x = 0.05 exhibited ultrahigh energy storage density, W, of approximately 9.14 J/cm³ and recoverable energy storage density, W_rec, of approximately 4.87 J/cm³ under a fairly low applied electrical field (220 kV/cm). These values exceed the highest values ever reported for KNN-based bulk ceramics. In addition, both excellent fatigue endurance (10⁵ cycles) and temperature stability (Δε'/ε_100°C < 15 % in the range 30–390 °C) were realised with the 0.97KNN-0.03BZN ceramic. Their excellent energy storage properties render KNN-based ceramics potential candidates for application in pulsed-power systems.     

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.     

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.     

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.     

(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.     

Achieving high comprehensive energy storage properties of BNT-based ceramics via multiscale regulation

It is difficult to obtain high polarization strength and high breakdown strength synchronously, resulting in the drawback of lower energy storage density, which inhibits commercial application of energy storage materials. We have successfully prepared (1-x)(0.93Bi_0.5Na_0.5TiO₃-0.07CaSnO₃)-xSrTiO₃ (BNT–CS–xST) ceramics by solid-state method. The presence of polymorphic nanodomains and the large electric displacement generated by the high charge Sr²⁺-Sr²⁺ ion pairs help to delay saturation polarization (P_m ∼ 48.64 μC/cm² at 315 kV/cm). In addition, the breakdown field strength (E_b) is increased by grain refinement and increasing the band gap. It is noteworthy that a high recoverable energy storage density (W_rec = 4.2 J/cm³) and a great efficiency (η = 88%) were achieved simultaneously in BNT–CS–0.5ST ceramic. Moreover, excellent charge-discharge performance was also achieved, with a discharge energy density W_d of 2.2 J/cm³, a current density C_D of 1724 A/cm² and a power density P_D of 250 MW/cm³. The study demonstrates that the great potential of BNT–CS–xST ceramics in power storage devices and provides an effective strategy for designing ceramics dielectric capacitors with excellent performance.     

Realizing high comprehensive energy storage performances of BNT-based ceramics for application in pulse power capacitors

Lead-free ceramic capacitors play an important role in electrical energy storage devices because of their ultrafast charge/discharge rates and high power density. However, simultaneously obtaining large energy storage capability, high efficiency and superior temperature stability has been a huge challenge for practical applications of ceramic capacitors. Here, the relaxor ferroelectric (1-x)[0.8Bi_0.5Na_0.5TiO₃-0.2Ba(Zr_0.3Ti_0.7)O₃]-xSr_0.7La_0.2TiO₃ ((1-x)(BNT-BZT)-xSLT) ceramics are prepared through solid-state reaction method to obtain excellent comprehensive energy storage performances. Particularly, high recoverable energy density (W_rec ～ 2.6 J/cm³) as well as superior efficiency (η ～ 92.2 %) can be achieved simultaneously under 210 kV/cm with composition of x = 0.3. Meanwhile, the corresponding ceramic shows excellent temperature (20?140 °C), frequency (1?200 Hz) and cycle stabilities (10⁶ st). Additionally, the 0.7(BNT-BZT)-0.3SLT ceramic also displays high power density (P_D ～ 38.8 MW/cm³) and extremely short discharge time (τ_0.9 ～ 0.11 μs). Therefore, this study provides a useful guideline for designing novel BNT-based ceramics with superior comprehensive energy storage performances.     

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.     

High energy storage and ultrafast discharge in NaNbO3-based lead-free dielectric capacitors via a relaxor strategy

Dielectric capacitors with decent energy storage and fast charge-discharge performances are essential in advanced pulsed power systems. In this study, novel ceramics (1-x)NaNbO₃-xBi(Ni_2/3Nb_1/3)O₃(xBNN, x = 0.05, 0.1, 0.15 and 0.20) with high energy storage capability, large power density and ultrafast discharge speed were designed and prepared. The impedance analysis proves that the introducing an appropriate amount of Bi(Ni_0·5Nb_0.5)O₃ boosts the insulation ability, thus obtaining a high breakdown strength (E_b) of 440 kV/cm in xBNN ceramics. A high energy storage density (W_total) of 4.09 J/cm³, recoverable energy storage density (W_rec) of 3.31 J/cm³, and efficiency (η) of 80.9% were attained in the 0.15BNN ceramics. Furthermore, frequency and temperature stability (fluctuations of W_rec ≤ 0.4% over 5–100 Hz and W_rec ≤ 12.3% over 20–120 °C) were also observed. The 0.15BNN ceramics exhibited a large power density (19 MW/cm³) and ultrafast discharge time (~37 ns) over the range of ambient temperature to 120 °C. These enhanced performances may be attributed to the improved breakdown strength and relaxor behavior through the incorporation of BNN. In conclusion, these findings indicate that 0.15BNN ceramics may serve as promising materials for pulsed power systems.     

Improved energy storage performance of Bi(Mg0.5Ti0.5)O3 modified Ba0.55Sr0.45TiO3 lead-free ceramics for pulsed power capacitors

(1–x)Ba_0.55Sr_0.45TiO₃–xBi(Mg_0.5Ti_0.5)O₃ (x = 0, 0.08, 0.1, 0.12, 0.15, 0.2) ceramics were fabricated via a solid-state reaction route. The ultrahigh recoverable energy density (W_rec = 4.05 J cm^?3), efficiency (η = 78%), maximum polarization (P_max = 51.40 μC cm^?2), and high dielectric breakdown strength (BDS = 230 kV cm^?1) were achieved for the 0.9BST?0.1BMT ceramic. The fast discharge rate (t_0.9～0.14 μs), current density (C_D～637.02 A cm^?2), high power density (P_D～38.70 MW cm^?3), good temperature stability (20?180 °C), frequency stability (10?500 Hz), and fatigue endurance for cycling (10⁵) of 0.9BST?0.1BMT ceramic make it suitable for the development of energy-storage devices. The relaxor behavior with a high W_rec (3.06 J cm^?3) and η (93%) at BDS (220 kV cm^?1) was also achieved for the 0.8BST?0.2BMT ceramic. This study systematically investigates the correlation among the structural, dielectric, impedance, and energy storage properties of BMT-doped BST ceramics.     

High energy storage density under low electric fields in BiFeO3-based ceramics with max configurational entropy

Dielectric capacitors play an increasingly important role in power systems because of their fast charging and discharging speed. Applications are usually limited due to the low W_rec. We design materials with high values of ΔP(P_max-P_r) and recoverable energy storage density(W_rec) from the high entropy perspective. Two single phases with a large Curie temperature T_c difference have been selected, which leads to the enlarged entropy. The ceramics (Bi_0.85Nd_0.1Sm_0.05)_1-xBa_x)(Fe_1-xTi_x)O₃(BNSBFT_x) are prepared by the solid-state reaction. As x increases, the corresponding configuration entropy(S_config) goes from 1.4 R to 1.52 R. The increased entropy destroys the long-range order, accompanied by the reduced remanent polarization(P_r) and the improved W_rec. The W_rec of BNSBFT_0.5 ceramics reaches 4.9 J/cm³ at a low field of 250 kV/cm. Both temperature change(∼ 0.5% from 30 °C to 140 °C) and frequency variation(∼ 4.8% from 1 Hz∼50 Hz) in W_rec show excellent stability.     

High energy-storage density under low electric fields and improved optical transparency in novel sodium bismuth titanate-based lead-free ceramics

A novel (1-x)Na_0.5Bi_0.5TiO₃-xBaHfO₃ (abbreviated as (1-x)NBT-xBH) transparent ceramic was fabricated by the solid state reaction method. X-ray diffraction analysis showed that NBT-based transparent ceramics exhibit a cubic-like perovskite structure and the solid solubility of BH in NBT reached to 0.15. The Landau-Devonshire theory and I-E curves revealed that the transition between the antiferroelectric like phase and the ferroelectric phase deeply relies on the variation of composition and free energy. One sample (x = 0.15) was found to show a high dielectric constant (˜2418±10%) over the temperature range 57–400 °C. These ceramics also exhibited a high discharge energy density (W_d) of 2.1 J/cm³ and a high maximum polarization P_m of 34 μC/cm² under relatively low electric fields which were less than 175 kV/cm. There was also high transparency in the visible spectra (more than 0.5) when the sample thickness was 250 μm.     

Excellent energy storage performance of NaNbO3-based antiferroelectric ceramics with ultrafast charge/discharge rate

Dielectric capacitors have drawn increasing attention due to their fast charge/discharge rates and high power density. Among all known ceramic dielectric materials, antiferroelectrics are more attractive for their unique double ferroelectric hysteresis loops and higher energy densities. Here, a series of antiferroelectric ceramics x(0.95Bi_0.5Na_0.5TiO₃-0.05SrZrO₃)-(1-x)NaNbO₃ (xBNTSZ-(1-x)NN, x = 0.23, 0.30, 0.35, 0.50) have been prepared. By stabilizing the antiferroelectric phase and postponing the critical electric field of the antiferroelectric-ferroelectric phase transition, an impressive discharge energy storage density of 4.08 J/cm³ at a breakdown strength of 370 kV/cm was achieved for the 0.35BNTSZ-0.65 N N. A superior comprehensive performance for the 0.50BNTSZ-0.50 N N ceramic with a discharge energy storage density (W_dis) of 3.78 J/cm³ and an efficiency of 86 % at an electric field strength of 320 kV/cm along with excellent frequency, temperature, and fatigue stabilities (fluctuations of W_dis≤±5% within 0.01∼100 Hz, W_dis≤10 % over 20∼140 °C, and W_dis≤1% over 10⁶ cycle numbers) is realized. Furthermore, 0.50BNTSZ-0.50 N N ceramics simultaneously exhibit a high current density (622.5 A/cm²), high power density (112 MW/cm³), and fast discharge rate (t = 47 ns), all of which make it an excellent candidate for the pulsed power devices.     

High energy-storage density and efficiency in PbZrO3-based antiferroelectric multilayer ceramic capacitors

The utilization of antiferroelectric (AFE) materials is commonly believed as an effective strategy to improve the energy-storage density of multilayer ceramic capacitors (MLCCs). Unfortunately, the inferior energy conversion efficiency (η) leads to high energy dissipation, which severely restricts the broader applications of MLCCs due to the increased probability of materials and/or devices failure. Herein, AFEs featuring large polarization response and small hysteresis loss are proposed to make up for deficiencies. Guided by this proposal, (Pb_0.94La_0.04)(Zr_0.69Sn_0.30Ti_0.01)O₃ AFE MLCC (abbreviated as M2) are manufactured. An ultrahigh W_rec of 16.1 J/cm³ and an excellent η of 90.9% are achieved simultaneously. Additionally, a great discharge energy density (W_dis) of 8.8 J/cm³ and a large power density (P_D) of 165.6 MW/cm³ are obtained synchronously. Noticeably, M2 exhibits excellent frequency-insensitive, temperature-bearable, and fatigue cycle-endurable energy-storage performances and/or charge-discharge properties. These results indicate that M2 has a promising prospect in advanced power electronic and/or pulsed power systems.     

Ultra-fast charge-discharge and high energy storage density realized in NaNbO3–La(Mn0.5Ni0.5)O3 ceramics

Lead-free antiferroelectric (AFE) NaNbO₃ (NN) is one of promising materials for dielectric capacitors, but the recoverable energy-storage density and efficiency get restrained owing to huge remanent polarization and limited dielectric breakdown field strength. In this work, a variety of NN based lead-free bulk (1-x)NaNbO₃-xLa(Mn_0.5Ni_0.5)O₃ (abbreviated as (1-x)NN-xLMN, x = 0, 0.05, 0.10, 0.15, 0.20) ceramics were designed using a solid-state synthesis method. Remarkably, an ultra-fast charge-discharge speed 47 ns and an acceptable recoverable energy-storage density W_rec ~1.77 J/cm³ with a high efficiency η = 77% were obtained under the E_b of 200 kV/cm at x = 0.05. The superior energy storage performance is attributed to the regulation of domain size and voltage resistance by special ions substitution of A and B sites. This work not only proposes an efficient strategy to realize high recoverable energy-storage density and efficiency, but also provide an candidate material for application of advanced pulsed power capacitors.