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.     

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.     

Study of the structure,electrical properties,and energy storage performance of ZnO-modified Ba0.65Sr0.245Bi0.07TiO3 Pb-free ceramics

Barium titanate ceramic is frequently used as a ferroelectric material and can be applied in the pulse power field in energy storage devices. Its properties, including dielectric, ferroelectric, and energy storage properties, can be significantly improved through doping. In this work, we prepared a series of (1-x)Ba_0.65Sr_0.245Bi_0.07TiO₃-xZnO (x = 0.005, 0.01, 0.02, 0.03) lead-free bulk relaxor ferroelectric ceramics by a traditional die-pressing processing route. The uniformity of the grain sizes for these ceramics was improved, and the grains were refined when a certain amount of ZnO was introduced into BaTiO₃-based ceramics. In addition, the breakdown strength was improved in the case where the relaxor behavior was not significantly improved. It should be noted that the sample doped with 0.02 mol Zn showed the maximum room-temperature storage density (1.51 J/cm³) at the largest electric field strength (210 kV/cm). At the same time, this ceramic exhibited good stability to temperature (60–150 °C) and frequency (10–100 Hz) variations, as well as fantastic fatigue resistance (10,000 charge-discharge cycles). This paper presents in-depth studies of the structure, morphology, electrical properties, and energy storage performance of ZnO-modified BaTiO₃-based ceramics.     

Enhanced energy-storage properties of (1-x)(0.7Bi0.5Na0.5TiO3-0.3Bi0.2Sr0.7TiO3)-xNaNbO3 lead-free ceramics

A series of (1-x)(0.7Bi_0.5Na_0.5TiO₃-0.3Bi_0.2Sr_0.7TiO₃)-xNaNbO₃ (BNT-BST-100xNN) lead-free ceramics were fabricated using conventional solid-state reaction technique. The phase behavior, microstructure, dielectric, ac impedance and energy-storage properties of the sintered ceramics were systematically investigated. XRD patterns and surface SEM micrographs revealed the introduction of NaNbO₃ didn't change the perovskite structure of BNT-BST at low doping level. The NaNbO₃ doping gave rise to slimmer P-E loops and thus gained enhanced energy storage properties. Therefore, a maximum energy storage density of 1.03 J/cm³ was achieved at 85 kV/cm at x = 0.01 via increasing the dielectric breakdown strength (DBS). Temperature-dependent dielectric permittivity illustrated the enhanced relaxor characteristics, implying the long-rang ferroelectric order was further damaged due to the introduction of NaNbO₃. The results above indicate the sintered ternary ceramics can be a promising lead-free candidate for energy storage capacitors.     

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 storage density in BiFeO3-BaTiO3-AgNbO3 lead-free relaxor ceramics

Lead-free (0.70-x)BiFeO₃-0.30BaTiO₃-xAgNbO₃+5‰mol CuO (abbreviated as BF-BT-xAN) ceramics were fabricated using a modified thermal quenching technique. BF-BT-xAN ceramics are of a perovskite structure with morphotropic phase boundary (MPB) and show strong relaxor properties. Remarkably, the high recoverable energy storage density of 2.11 J/cm³ is obtained for BF-BT-xAN with x = 0.14. For the x = 0.14 ceramics, its energy storage efficiency is as high as 84 % at relative low field of 195 kV/cm, together with an outstanding thermal stability in a broad temperature range from 25 °C to 150 °C. In addition, this ceramic maintains superior energy storage performance even after 8 × 10⁴ electrical cycles due to its high densification after doping Ag₂O and Nb₂O₅. The result suggests that lead-free BF-BT-xAN ceramics may be promising candidate for dielectric energy storage application.     

Decreasing polar-structure size: Achieving superior energy storage properties and temperature stability in Na0.5Bi0.5TiO3-based ceramics for low electric field and high-temperature applications

It is a grand challenge to achieve high energy density (W) and efficiency (η) simultaneously under a low electric field (LE) to obtain new high energy storage capacitors. Similar to anti-ferroelectrics, the (1-x)NBT-xBaMg_1/3Nb_2/3O₃ relaxor material exhibits a non-linear dependence on electric field, which is caused by a reversible field-induced phase transition. This leads to high W (2.37 J/cm³) and η (81.5 %) under a LE of 155 kV/cm, which makes it superior to other bulk ceramics. Combining large polarizability of Ba²⁺ in A-site and local structural heterogeneity on the B-site by Mg_1/3Nb_2/3⁴⁺, enhanced relaxor behavior and decreased polar-structure size were induced in (1-x)NBT-xBaMg_1/3Nb_2/3O₃ ceramics. The permittivity, nevertheless, stays high at ～2273±15 %. Furthermore, the electrical properties become stable in a wide temperature range from 44?396 °C for the sample with x=0.15. In addition, high current density/C_D (450 A/cm²), power density/P_D (23 MW/cm³) and discharge density/W_D (0.57 J/cm³) were realized tested with pulse discharge testing. Our work will provide a development guidance for dielectric energy storage ceramics at low field and high fields with excellent temperature stability.     

Simultaneously achieving high energy storage density and efficiency under low electric field in BiFeO3-based lead-free relaxor ferroelectric ceramics

BiFeO₃-BaTiO₃-based relaxor ferroelectric ceramic has attracted increasing attention for energy storage applications. However, simultaneously achieving high recoverable energy storage density (W_rec) and efficiency (η) under low electric field has been a longstanding drawback for their practical applications. Herein, a novel relaxor ferroelectric material was designed by introducing (Sr_0.7Bi_0.2)TiO₃ (SBT) into the composition 0.67BiFeO₃-0.33BaTiO₃ (BF-BT-xSBT). A large W_rec of ∼2.40 J/cm³ and a high η of ∼90.4 % were simultaneously realized under a low electric field of 180 kV/cm, which is superior to that of most previously reported lead-free ceramics. Moreover, moderate temperature endurance and excellent frequency stability were also obtained. More importantly, this ceramic has a large discharge current density (∼289.18 A/cm²), a discharge power density (∼14.46 MW/cm³) and short discharge time (<0.25 μs). These results not only demonstrate superior potential in BF-BT-SBT ceramics, but also offer a new design to tune the energy storage performance of lead-free relaxor ferroelectric ceramics.     

An alternative way to design excellent energy-storage properties in Na0.5Bi0.5TiO3-based lead-free system by constructing relaxor dielectric composites

With growing concerns over environmental protection, lead-free dielectric ceramic capacitors are attracting much attention. In this work, a series of novel (1-x) Na_0.5Bi_0.5TiO₃-x Ba₅LaTi₃Ta₇O₃₀ ((1-x)NBT-xBLTT) dielectric composite ceramics were fabricated by a traditional solid‐state method. All the samples possess a compact microstructure with refined grain morphology with increasing BLTT content, and tend to exhibit a diphase dielectric composite as x reaches up to 0.05. Furthermore, the addition of BLTT enhances the dielectric relaxor behavior of NBT-based ceramics, such that the x = 0.15 composite ceramic exhibits a typical feature of relaxor ferroelectrics. As a result, a high recoverable energy-storage density of W_rec~3.67 J/cm³, an ultrahigh energy-storage efficiency of η~97.3%, and a high power density of P_D~333 MW/cm³ can be simultaneously obtained in the x = 0.15 relaxor composite ceramic. This study provides an alternative way to design excellent energy-storage performances in NBT-based compositions through constructing dielectric relaxor composites via introducing non-polar tungsten bronze oxides.     

High recoverable energy storage density and large energy efficiency simultaneously achieved in BaTiO3–Bi(Zn1/2Zr1/2)O3 relaxor ferroelectrics

Relaxor ferroelectrics have attracted much attention as electric energy storage materials for intermittent energy storage because of their high saturated polarization, near-zero remnant polarizations, and considerable dielectric breakdown strength (BDS). Despite the numerous efforts, the dielectric energy storage performance of relaxor ferroelectric ceramics is incomplete or unsatisfactory. The enhancement of recoverable energy storage density W_rec usually accompanies with the sacrifice of discharge-to-charge energy efficiency η; therefore, it is an important issue to achieve high recoverable W_rec and large efficiency η simultaneously. In this work, the (1-x)BaTiO₃-xBi(Zn_1/2Zr_1/2)O₃ (abbreviated as BT-100xBZZ, 0 ≤ x ≤ 0.20) ferroelectric ceramics were prepared using the conventional solid-state reaction method. The phase structure, microstructural morphology, dielectric and ferroelectric properties, relaxation behaviors, and energy storage properties of BT-BZZ ceramics were investigated in detail. X-ray powder diffraction, dielectric spectra, and ferroelectric properties confirm the transformation of tetragonal phase for normal ferroelectrics (BT) to pseudo-cubic phase for relaxor ferroelectrics (BT-8BZZ). A high recoverable energy storage density W_rec of 2.47 J/cm³ and a large energy efficiency η of 94.4% are simultaneously achieved in the composition of BT-12BZZ, which presents typical weakly coupled relaxor ferroelectric characteristics, with an activation energy E_a of 0.21 eV and a freezing temperature T_f of 139.7 K. Such excellent energy storage performance suggests that relaxor ferroelectric BT-12BZZ ceramics are promising dielectric energy storage materials for high-power pulsed capacitors.     

High recoverable energy storage density in nominal (0.67-x)BiFeO3-0.33BaTiO3-xBaBi2Nb2O9 lead-free composite ceramics

A series of novel lead-free energy storage ceramics, (0.67-x)BiFeO₃-0.33BaTiO₃-xBaBi₂Nb₂O₉ (BF-BT-xBBN), were fabricated by traditional solid-state reaction, where bismuth layer-structured BaBiNb₂O₉ was incorporated into perovskite-structured BiFeO₃–BaTiO₃ ceramic as an additive. The addition of BaBi₂Nb₂O₉ increased the relaxor behavior and breakdown strength of BF-BT ceramics due to the formation of polar nanoregionals (PNRs), inducing enhanced energy storage performance. The composite ceramics, with x = 0.08, showed a large recoverable energy density (W_rec) of 3.08 J/cm³ and an outstanding energy storage efficiency (η) of 85.57% under an applied electric field of 230 kV/cm. Moreover, the composite ceramics exhibited excellent thermal stability and high stability toward different frequencies in a temperature range of 20–100 °C and a frequency range of 0.1–1500 Hz. These results demonstrate great potential of novel BF-BT-xBBN composite ceramics for next-generation energy storage applications.     

Realizing high-performance capacitive energy storage in lead-free relaxor ferroelectrics via synergistic effect design

Developing lead-free dielectric ceramics with outstanding energy storage properties has become urgent for dielectric capacitors. Herein, a synergistic effect design strategy has been proposed that combined the merits of relaxor ferroelectrics with high polarization/low remanent polarization and enhanced linear materials with relatively high polarization/ultrahigh dielectric breakdown strength. Hence, a novel lead-free 0.955Bi_0.5Na_0.5TiO₃-0.045Ba(Al_0.5Ta_0.5)O₃-based ceramics are engineered though introducing the enhanced linear dielectrics of 0.9CaTiO₃-0.1BiScO₃. A large recoverable energy density (W_rec～3.13 J/cm³) and high efficiency (η～88.4 %) as well as excellent power density (P_D～95.1 MW/cm³) and discharge speed (t_0.9～36 ns), along with superior stabilities, have been simultaneously realized. The piezoelectric force microscope measurements reveals that incorporating CT-BS generates more highly-dynamic polar nanoregions (PNRs), giving rise to rapid reversibility of PNRs with concurrently tailored energy storage performance. This study demonstrates synergistic effect design is a feasible and paradigmatic way to explore high-efficiency dielectrics for high-power energy storage applications.     

Enhanced energy-storage properties and dielectric temperature stability of (Bi0·5Na0.5)0.84Sr0·16Ti1-x(Y0·5Nb0.5)xO3 lead-free ceramics

A series of lead-free (Bi_0·5Na_0.5)_0.84Sr_0·16Ti_1-x(Y_0·5Nb_0.5)_xO₃ (abbreviated as BNST-100xYN) relaxor ferroelectric ceramics were prepared by solid state reaction sintering. The micro morphology, dielectric properties, and energy storage properties of the ceramics with increasing doping content were systematically studied, and their conductive mechanism was also studied. The perovskite structure was not significantly changed with the addition of (Y_0·5Nb_0.5)⁴⁺ complex ions, but it led to a certain amount of flake grains appear and element precipitation with increasing composition. And the larger dielectric breakdown strength (DBS) and lower remanent polarization (P_r) were attained with the recoverable energy storage density (W_rec) of ~1.0433 J/cm³ for x = 0.04 composition. In addition, it showed outstanding dielectric temperature stability and cycle stability. These results indicated that BNST-4YN ceramics are an excellent candidate for energy storage device and temperature-stable dielectric equipment.     

Excellent energy storage properties over a wide temperature range under low driving electric fields in NBT-BSN lead-free relaxor ferroelectric ceramics

To develop environment-friendly dielectric capacitors with low working electric field and wide useable temperature, in this work, we fabricate (1-x)Na_0.46Bi_0.54TiO₃- xBaSnO₃((1-x)NBT-xBSN) lead-free relaxor ferroelectric ceramics by adding BaSnO₃ into Na_0.46Bi_0.54TiO₃ matrix. BSN exhibits slim polarization-electric field (P-E) loops, small remnant polarization (P_r) and good temperature stability because of its room-temperature paraelectric characteristics, and has different cation ionic radii with Na_0.46Bi_0.54TiO₃. Therefore, when BSN is introduced into NBT, the relaxor behavior of the (1-x)NBT-xBSN ceramics is more pronounced and the P-E loops are much slimmer. Besides, because the substitution of Ba²⁺ ions with higher valence for Na⁺ ions neutralizes the hole carriers, which are caused by the volatilization of Na₂O, the resistivity and breakdown strength are improved with increasing BSN content. As a consequence, at x = 0.30, the ceramic exhibits simultaneously a large recoverable energy density (W_rec) of 1.51 J/cm³ and high energy efficiency (η) of 81.2% at a low driving electric field of 145.3 kV/cm because of the collaborative enhancement effect of the high breakdown strength and low remnant polarization. More interestingly, variations of the W_rec and the η for this kind of ceramic are respectively as small as 10% and 0.8% over a wide temperature range of 20–140 °C, demonstrating superior temperature stability. In this report, we provide a new and efficient way for designing and fabricating environment-friendly dielectric capacitors with good reliability and superior high-temperature energy storage capacity.     

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.     

Lead-free BaTiO3-Bi0.5Na0.5TiO3-Na0.73Bi0.09NbO3 relaxor ferroelectric ceramics for high energy storage

A series of (1-x)(0.65BaTiO₃-0.35Bi_0.5Na_0.5TiO₃)-xNa_0.73Bi_0.09NbO₃ ((1-x)BBNT-xNBN) (x = 0–0.14) ceramics were designed and fabricated using the conventional solid-state sintering method. The microstructure, dielectric property, relaxor behavior and energy storage property were systematically investigated. X-ray diffraction results reveal a pure perovskite structure and dielectric measurements exhibit a relaxor behavior for the (1-x)BBNT-xNBN ceramics. The slim polarization electric field (P-E) loops were observed in the samples with x ≥ 0.02 and the addition of Na_0.73Bi_0.09NbO₃ (NBN) could decrease the remnant polarization (P_r) of the (1-x)BBNT-xNBN ceramics obviously. The sample with x = 0.08 exhibits the highest energy storage density of 1.70 J/cm³ and the energy storage efficiency of 82% at 172 kV/cm owing to its submicron grain size and high relative density. These results show that the (1-x)BBNT-xNBN ceramics may be promising lead-free materials for high energy storage density capacitors.     

Anomalously large lattice strain contributions from rhombohedral phases in BiFeO3-based high-temperature piezoceramics estimated by means of in-situ synchrotron x-ray diffraction

Thermally-stable (0.75-x)BiFeO₃-0.25PbTiO₃-xBa(Zr_0.25Ti_0.75)O₃ (0.1?≤?x?≤?0.27) piezoelectric ceramics were reported to have excellent dielectric and electromechanical properties of d₃₃～405 pC/N, k_p～46%, ε₃₃^T/ε₀～1810, tanδ～3.1% and T_c～421?°C close to tetragonal (T)-rhombohedral (R) morphotropic phase boundary. The dielectric measurement indicates that R ferroelectric phase is gradually transformed into relaxor ferroelectric across the phase boundary due to the substitution of BZT for BF. The transmission electron microscopy and convergent beam electron diffraction provide clear evidences that both the R-T phase coexistence and polar nanodomains contribute to enhanced piezoelectric properties at x?=?0.19 through cooperatively facilitating polarization orientation. In combination with the macroscopic piezoelectric coefficient measurement, the quantitative analysis of synchrotron diffraction data under electric fields suggests that extremely large lattice strain contribution predominantly from R phases plus little extrinsic domain switching contribution should dominate the piezoelectric response of the x?=?0.19 sample, mainly owing to both irreversible field-induced T to R phase transition and irreversible non-180° domain switching.     

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.     

Significantly reduced hysteresis in (Fe1/2Nb1/2)4+-modified 0.75Na1/2Bi1/2TiO3-0.25SrTiO3 lead-free piezoceramics with large strain

Aiming to get the NBT-based lead-free ceramic with high strain and low strain hysteresis for practical actuator applications, a solid solution of complex-ion (Fe_1/2Nb_1/2)⁴⁺doped 0.75Na_1/2Bi_1/2TiO₃-0.25SrTiO₃ ((Na_1/2Bi_1/2)_0.75Sr_0.25Ti_1-x(Fe_1/2Nb_1/2)_xO₃, abbreviated as NBST-100xFN) was designed and prepared, and its phase structure, micromorphology, ferroelectric, strain, dielectric and piezoelectric performances were systematically investigated. It was found that the incorporation of (Fe_1/2Nb_1/2)⁴⁺ causes a structure transition from the ferroelectric/relaxor (FE/RE) mixed phases to relaxor (RE) phase, increasing to a promising strain performance at x = 0.04 featured by not only a moderate strain value of 0.26%, corresponding normalized strain d₃₃* of 371 pm/V, but also a very small strain hysteresis of 22%. In addition, the NBST-4FN ceramic sample also exhibits an unexceptionable frequency-dependence of unipolar strain. This study provides a new understanding and design idea for the practical actuator application of high strain NBT-based lead-free ceramics with ultra-low hysteresis.     

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.