(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.     

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.     

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.     

High energy storage properties of lead-free Mn-doped (1-x)AgNbO3-xBi0.5Na0.5TiO3 antiferroelectric ceramics

In this work, 0.2 wt.% Mn-doped (1-x)AgNbO₃-xBi_0.5Na_0.5TiO₃ (x = 0.00–0.04) ceramics were synthesized via solid state reaction method in flowing oxygen. The evolution of microstructure, phase transition and energy storage properties were investigated to evaluate the potential as high energy storage capacitors. Relaxor ferroelectric Bi_0.5Na_0.5TiO₃ was introduced to stabilize the antiferroelectric state through modulating the M₁-M₂ phase transition. Enhanced energy storage performance was achieved for the 3 mol% Bi_0.5Na_0.5TiO₃ doped AgNbO₃ ceramic with high recoverable energy density of 3.4 J/cm³ and energy efficiency of 62% under an applied field of 220 kV/cm. The improved energy storage performance can be attributed to the stabilized antiferroelectricity and decreased electrical hysteresis ΔE. In addition, the ceramics also displayed excellent thermal stability with low energy density variation (<6%) over a wide temperature range of 20−80 °C. These results indicate that Mn-doped (1-x)AgNbO₃-xBi_0.5Na_0.5TiO₃ ceramics are highly efficient lead-free antiferroelectric materials for potential application in high energy storage capacitors.     

Improved dielectric energy storage performance of Na0.5Bi0.5TiO3–Sr0.7Nd0.2TiO3 lead-free ceramics by adding an appropriate amount of AgNbO3

Based on the significant advantages of dielectric ceramics in high power energy storage, (1-x) (0.55Bi_0.5Na_0.5TiO₃-0.45Sr_0.7Nd_0.2TiO₃)-xAgNbO₃ (NBSNT-xAN) ceramics were prepared by traditional solid phase method. The introduction of AN in NBSNT ceramics not only increased the degree of relaxation, but also refined the grain size, enhanced the BDS, and finally improved the energy storage performance. It is found that the NBSNT-0.5AN ceramics obtained an effective energy storage density as high as 3.08 J/cm³ and an efficiency of 79.94%. In addition, good thermal stability and temperature stability were exhibited in the range of 30–120 °C and 10–350 Hz, and at the same time, it performed very well in the pulsed test at room temperature and variable temperatures. This provides a design idea for the miniaturization and integration of energy storage ceramic materials.     

Bi0·5Na0·5TiO3–Sr0.85Bi0·1TiO3 ceramics with high energy storage properties and extremely fast discharge speed via regulating relaxation temperature

Bi_0·5Na_0·5TiO₃-based relaxor ferroelectric ceramics have recently gained increasing attention due to their outstanding energy storage properties. However, the trade-off between the recoverable energy storage density/efficiency and discharge rate resulted from the hysteresis of domain switching process, severely limits their applications. Herein, a strategy realizing synergistic excellent energy storage properties and fast discharge rate is proposed through regulating relaxation temperature. The relaxation temperature was decreased to below room temperature by introducing Sr_0·85Bi_0·1TiO₃ into Bi_0·5Na_0·5TiO₃ [(1-x)Bi_0·5Na_0·5TiO₃-xSr_0.85Bi_0·1TiO₃, x = 0.5–0.7)], enabling the small size and weak correlation polar nanoregions (PNRs) with relatively high polarization. The trade-off was overcome by reducing the hysteresis of electrical switching of weak correlation PNRs. Thus, large recoverable energy storage density of 2.32 J/cm³ and high efficiency of 80.1% (250 kV/cm) were achieved simultaneously for x = 0.7 ceramics. Meanwhile, extremely rapid discharge rate (<30 ns) and remarkable power density of 63.7 MW/cm³, which were superior to the previously reported lead-free ceramics were realized. Besides, the 0.3BNT-0.7SBT ceramics also possess good thermal stability over 25 °C–115 °C at 100 kV/cm and good frequency stability (5–100 Hz). These properties make the 0.3BNT-0.7SBT ceramic an ideal candidate for energy storage applications.     

Enhanced dielectric energy storage performance of A-site Ca2+-doped Na0.5Bi0.5TiO3–BaTiO3–BiFeO3 Pb-free ceramics

(1-x) (0.98Na_0.5Bi_0.5TiO₃–0.01BaTiO₃–0.01BiFeO₃)–xCaTiO₃ (NBB-xCT) ceramics were produced using traditional solid-state synthesis methods. The surface morphology, domain structure, and electrical properties of the ceramic samples were systematically studied. In addition, the temperature and frequency stabilities of the NBB-15CT sample at 200 kV/cm were tested. Generally, NBB-xCT ceramics exhibit a typical single perovskite phase structure. The results indicate that the NBB-15CT ceramics showed a high energy density of 3.14 J/cm³ at 250 kV/cm. The piezoresponse force microscopy (PFM) results showed that the addition of CT broke the macrodomains of the 0.98Na_0.5Bi_0.5TiO₃-0.01BaTiO₃-0.01BiFeO₃ ceramic and helped to form nanodomains, leading to an improved energy storage performance. The above performance indicates that the specimens possess very good temperature-and frequency-dependent energy storage performances at 30–150 °C and 1–100 Hz. Moreover, the electric energy storage and release in the NBB-15CT ceramic indicated that the power density could reach 55.30 MV/cm³ at 180 kV/cm. Therefore, the NBB-15CT ceramic is a promising material for electrical capacitors.     

Achieving high energy storage performance below 200 kV/cm in BaTiO3-based medium-entropy ceramics

A small applied electric field is particularly crucial in the practical application of dielectric ceramic capacitors, since it means a longer lifetime of the capacitors in practical energy storage applications. Based on the traditional ferroelectric BaTiO₃, the (1-x)(Ba_0.6Na_0.2Bi_0.2)TiO₃-xNaNbO₃ medium-entropy material is designed in this paper, which correlates configuration entropy with energy storage performance. The findings demonstrate that the BNBT-0.15NN ceramic synchronously achieves high energy storage density (2.95 J/cm³) and the energy storage efficiency (95.2%) at 180 kV/cm when the configuration entropy rises to 1.43R. The idea of medium-entropy energy storage under low electric field is proposed for the first time, opening up a new avenue for research into the preparation of high energy storage dielectric ceramics via exploring medium-entropy composition.     

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.     

Stabilizing temperature-capacitance dependence of (Sr,Pb, Bi)TiO3-Bi4Ti3O12 solutions for energy storage

(1-x)Sr_0.7Pb_0.15Bi_0.1TiO₃-xBi₄Ti₃O₁₂ ((1-x)SPBT-xBIT, x = 0-0.125) bulk ceramics were developed and calcined via the solid-state method, aimed at the application of pulsed power capacitors. The phase structures, temperature stability, hysteresis loop, and discharge properties were systematically investigated. Considering both the temperature stability and dielectric properties, 0.925SPBT-0.075BIT bulk ceramics with a capacitance variation satisfying the X7R specification were developed for pulsed power capacitors. The energy storage density was 0.252 J/cm³, and the ceramics showed high temperature stability at 80 kV/cm. The discharge current waveforms of the 0.925SPBT-0.075BIT ceramics were recorded. A high discharge power density of approximately 1.01 × 10⁸ W/kg with an 8 Ω load resistor and short discharge period of 84 ns were achieved at 50 kV/cm. The good temperature stability properties and high power density show that the 0.925SPBT-0.075BIT ceramics are well suited for pulsed power capacitors with a wide temperature range.     

Simultaneously enhanced energy storage density and efficiency in novel BiFeO3-based lead-free ceramic capacitors

In this work, a series of novel lead-free (1-x)Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃-x(0.85BaTiO₃-0.15Bi(Mg_0.5Zr_0.5)O₃) [(1-x)BSFS-x(BT-BMZ), x = 0.45?0.85] relaxor ceramics were prepared by solid phase sintering, and their dielectric properties and energy storage performances were explored. It was revealed that all the samples have a dense structure with pure pseudo-cubic phase. With the increase of x, the ferroelectric hysteresis loop is gradually slimmed accompanied by a decreasing polarization, indicating an enhanced relaxor behavior. Moreover, the electric breakdown strength increases linearly with x due to the fine grain size and enhanced relative density. Interestingly, a large recoverable energy density (～3.2 J/cm³) with an outstanding efficiency (～92 %) is achieved under an electric field ～206 kV/cm for the optimized component x = 0.75, which is superior to other reported lead-free ceramic systems. Moreover, the optimized ceramics of 0.25BSFS-0.75(BT-BMZ) show good thermal stability (25?100 °C) and excellent fatigue endurance (cycle number: > 10⁵) in energy storage performances. This work opens up a new route to tailor lead-free dielectric ceramics with high energy storage properties.     

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.     

Excellent thermal stability,high efficiency and high power density of (Sr0.7Ba0.3)5LaNb7Ti3O30–based tungsten bronze ceramics

A series of (1-x)(Sr_0.7Ba_0.3)₅LaNb₇Ti₃O₃₀–x(Bi_0.5Na_0.5)TiO₃ (x = 0.1–0.4) ceramics with tungsten bronze structure were prepared by solid state reaction. Phase composition, microstructure and energy storage properties were studied. When x = 0.3, excellent thermal stability satisfying the X7R specification was obtained and its energy storage as well as charge-discharge performances were further evaluated. Release energy density (W_re) of 0.77 J/cm³ and an energy storage efficiency of 97.3 % were detected at a low electric field of 20 kV/mm. Under the electric field of 10 kV/mm, the change of W_re in the temperature range of −55 °C to 125 °C is less than 15 % compared to room temperature. Short discharge period (∼0.17 μs), high power density (61.2 MW/cm³) and high discharge energy density (2.45 J/cm³) were evaluated by charge-discharge tests. Excellent thermal stability, high energy storage efficiency and high power density indicate that 0.7(Sr_0.7Ba_0.3)₅LaNb₇Ti₃O₃₀–0.3(Bi_0.5Na_0.5)TiO₃ ceramic is a promising pulse capacitor for working over a wide temperature range.     

Enhancement of energy-storage properties in BiFeO3-based lead-free bulk ferroelectrics

Dielectric capacitors with a high power density and fast charging/discharging rate are regarded as alternatives for energy storage applications. However, lower energy storage density and efficiency are critical issues that have to be addressed for applications as energy storage capacitors. (0.7-x)BiFeO₃ - 0.3BaTiO₃ - xBaZn_1/3Nb_2/3O₃ + 0.1 wt%MnO₂ (BFO-BTO-BZNO) ceramics were prepared via the conventional solid-state reaction approach. Both the temperature dependence of dielectric constant and slim P-E hysteresis loops confirm that (BFO-BTO-BZNO) ceramics were relaxor ferroelectrics. Furthermore, the energy storage densities and efficiencies of (BFO-BTO-BZNO) were calculated based on the hysteresis loops and direct measurements of the discharged pulse currents measured at room temperature. The results indicate that the doping of BZNO can adjust the maximum and remnant polarizations of BFO-BTO based bulk ceramics, thereby affecting the energy storage properties. And the maximum energy storage density obtained was 1.61 J/cm³ at 180 kV/cm and room temperature.     

Enhanced energy storage properties and large electrostrictive effect of Bi0.35Na0.35Ba0.09Sr0.21Ti(1-x)(Al0.5Nb0.5)xO3 relaxor ceramics

Ferroelectric ceramics have good piezoelectric and ferroelectric properties and can be used for energy storage equipment and actuators. Nevertheless, current research on dielectric capacitors has only focused on the energy storage density, but ignored efficiency. Moreover, conventional piezoelectric materials have a large strain hysteresis. In this work, (Al_0.5Nb_0.5)⁴⁺ (AN) complex ions doped 0.7Bi_0.5Na_0.5TiO₃-0.3Ba_0.3Sr_0.7TiO₃ (BNBST) ceramics were prepared. Doping AN destroyed the long-range ordered ferroelectric domains and generated polar nano regions, resulting in a gradual thinning and inclination of polarization hysteresis loops and an increase in relaxor degree. For BNBST-3AN ceramics, a W_rec of 1.52 J/cm³ and a η of 92.1% were achieved at 150 kV/cm. Meanwhile, BNBST-3AN ceramics had good energy storage temperature stability and cycling performance. The AN doping reduced the strain hysteresis in BNBST ceramics. BNBST-2AN ceramics exhibited a longitudinal electrostrictive coefficient Q₃₃ ～ 0.0292 m⁴/C² and a field-induced strain of 0.25% with low strain hysteresis (6.67%). Furthermore, BNBST-4AN ceramics had superior dielectric temperature stability from 24 to 270 °C. All results show that BNBST-100xAN ceramics have great promise for energy storage devices and actuators.     

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.     

Combining high energy efficiency and fast charge-discharge capability in novel BaTiO3-based relaxor ferroelectric ceramic for energy-storage

Compared with the other types of ceramic capacitors, relaxor ferroelectric ceramics demonstrate superior potential in energy-storage fields due to their higher energy efficiency, faster charge-discharge rate, and better temperature stability. In this study, we designed and synthesized a novel high performance BaTiO₃-based ((1-x)BaTiO₃-xBi(Ni_2/3Nb_1/3)O₃, x?=?0.08, 0.10, 0.12, and 0.14) energy-storing ceramics through ferroelectric properties modulation, which display typical relaxor characteristics. The optimum energy storage properties, i.e. ultrahigh energy efficiency (95.9%), high energy-storage density (2.09?J?cm^?3) and good temperature stability (the fluctuations in energy-storage properties are less than 5% over 20–120?°C) are obtained at x?=?0.12 (0.88BT-0.12BNN). The 0.88BT-0.12BNN relaxor ferroelectric ceramic demonstrates obviously superior comprehensive energy-storage properties than most of other unleaded ceramics. Besides, investigation efforts were also spent on the pulsed charge-discharge performance of the 0.88BT-0.12BNN ceramic to evaluate its feasibility as energy-storage devices. More importantly, the 0.88BT-0.12BNN ceramic also exhibits outstanding charge-discharge performance with fast discharge rate (t_0.9 <?100?ns), a high level of power density (36.9?MW?cm^?3), and good temperature stability. These excellent performance parameters qualify this novel and environmentally friendly BaTiO₃-based ceramic as a promising alternative option in energy-storage section. Meanwhile, this study also provides an effective approach to attain high energy-storage density as well as energy efficiency in BaTiO₃-based relaxor ferroelectric ceramics.     

Tunable BaxSr1-xTiO3 nanoparticles induced high energy storage density in layer-structured asymmetric polymer-based nanocomposites

In order to solve the problem of low charging and discharging energy density of dielectric capacitors, the structure design of layered polymer matrix composites is carried out in this paper. Ba_0.7Sr_0.3TiO₃, Ba_0.8Sr_0.2TiO₃ and Ba_0.9Sr_0.1TiO₃ nanoparticles were successfully prepared by the oxalate coprecipitation method. The surface of Ba_xSr_1-xTiO₃ was successfully coated with dopamine, which promoted the dispersion of the polymer matrix of the ceramic powder. Monolayer Ba_xSr_1-xTiO₃/PVDF composites containing Ba_xSr_1-xTiO₃ with different Ba/Sr ratios were successfully prepared by the casting method. Three-layer asymmetric composites with different fillers were successfully prepared by layer-by-layer casting. The phase and microstructure of the as-prepared materials were analyzed by XRD and SEM. The dielectric, electrical conductivity, ferroelectric and energy storage properties of the composites were tested. The effects and laws of the design of the three-layer asymmetric structure on the dielectric properties and energy storage properties of the layered composites are mainly studied. When the structure of the three-layer asymmetric composite is 1-2-3, the breakdown field strength reaches 330 kV/mm, the discharge energy density reaches 8.51 J/cm³, and the charge-discharge efficiency is 67%. This work demonstrates that layered composites with asymmetric properties can facilitate the development of electrical energy storage.     

High energy storage density and temperature-stable dielectric properties for (1-x)Bi0.38Na0.38Sr0.24TiO3-xBaSnO3 lead-free relaxor ceramics

Relaxor ferroelectrics are promising candidates for energy storage equipment due to their excellent energy-storage properties. Lead-free (1-x)Bi_0.38Na_0.38Sr_0.24TiO₃-xBaSnO₃ (abbreviated as BNST-100xBS) relaxor ceramics were synthesized by a traditional solid-phase sintering method. The influences of the addition of BaSnO₃ dopants for the energy storage and dielectric temperature-stable properties of BNST-100xBS ceramics were systemically investigated. All samples exhibited a typical pseudo-cubic symmetry structure and obtained the dense microstructure. The ergodic relaxor behavior of all ceramics was observed and revealed a trend of increase as a function of composition. All samples showed a single grain conduction mechanism and the activation energy decreased with the addition of composition. It is related to the generation of oxygen vacancies induced by the defect dipoles. BNST-2.5BS ceramic exhibited an outstanding recoverable energy density of ~1.42 J/cm³ with the corresponding efficiency of ~79.7% at 115 kV/cm field. In addition, excellent temperature-stable permittivity (43–255 °C) was obtained for BNST-7.5BS ceramic. Hence, BNST-2.5BS ceramic revealed excellent energy density properties and BNST-7.5BS exhibited outstanding temperature-stable dielectric permittivity, which was beneficial to use in energy storage equipment and other device applications.     

Enhanced energy storage performances of CaTiO3-based ceramic through A-site Sm3+ doping and A-site vacancy

Ceramic-based capacitors for energy storage devices require simultaneously high energy density and efficiency. Achieving high electric breakdown field based on linear dielectrics is crucial. Here, A-site Sm³⁺ doped perovskite Ca_1-1.5xSm_x□_0.5xTiO₃ ceramics with introduced A-site vacancies (V_A) were prepared. All Ca_1-1.5xSm_x□_0.5xTiO₃ ceramics crystallize in an orthorhombic structure, with lattice constants a, b, and c linearly decreased. As a result of Sm³⁺ dopants and V_A, the grain size decreased while the ceramics’ density was improved. The permittivity decreases from 176 (x = 0) to 135 (x = 0.1), but tanδ is effectively constrained (～10^?4). What’s more, the dielectric breakdown strength is significantly improved from 429 kV/cm (x = 0) to 547 kV/cm (x = 0.1) with dielectric linearity is maintained. The optimum energy storage density of 2 J/cm³ (x = 0.02) with ultrahigh energy efficiency of over 93.7 % is achieved, which are superior to many existing linear dielectrics and relaxor ferroelectrics. This work confirms the energy-storage enhancement through chemical modifications and microstructural engineering.