Lead-free dielectric energy-storage ceramic material with self-assembled multiphase core-shell structure and preparation method of lead-free dielectric energy-storage ceramic material

Abstract

The invention relates to a lead-free dielectric energy storage ceramic material with a self-assembled multiphase core-shell structure and a preparation method thereof, and the preparation method comprises the following steps: taking ceramic raw materials according to the stoichiometric ratio of (1-x) [(1-y) Ba (Zr0. 1Ti0. 9) O3-yBi (Zn2 / 3Ta1 / 3) O3]-x (Bi0. 5Na0. 5) TiO3, and uniformly mixing to obtain a mixed raw material; carrying out pre-sintering, secondary ball-milling mixing, drying, sieving, granulating, pre-pressing molding and cold isostatic pressing on the mixed raw materials to prepare a ceramic green body; and sintering and cooling the ceramic green body to obtain the lead-free dielectric energy storage ceramic material. A proper amount of sodium bismuth titanate elements are subjected to solid solution in a lead-free ferroelectric ceramic material matrix, and after burdening and high-temperature sintering, a core-shell microstructure is spontaneously formed in ceramic crystal grains, so that the obtained lead-free dielectric energy storage ceramic material has high energy storage density, high breakdown electric field and high polarization intensity, and meanwhile, the process is simple, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of energy storage ceramic materials, specifically relating to a lead-free dielectric energy storage ceramic material with a self-assembled multiphase core-shell structure and its preparation method. Background Technology

[0002] Dielectric capacitors, due to their high power density, fast discharge rate, and good cycle stability, have been widely used in key areas such as advanced pulsed power electronic systems and new energy equipment, becoming one of the current research hotspots in the field of energy storage materials. With the rapid development of devices towards miniaturization and integration, traditional lead-containing dielectric materials are unable to meet future demands due to environmental pollution issues. Therefore, the development of high-performance lead-free dielectric energy storage materials has become an industry consensus and an urgent need. However, lead-free dielectric materials generally have a limited recoverable energy density (…). W rec ) and breakdown electric field ( E b The core bottleneck that makes it difficult to improve in a coordinated manner has become a key factor restricting its further application.

[0003] In existing technologies, improving performance is achieved by controlling the microstructure. E b This is a common approach. For example, grain refinement and the introduction of sintering aids can increase the proportion of high-resistivity grain boundaries and reduce porosity, which helps improve material density and breakdown performance. However, excessive grain refinement can lead to an excessive number of grain boundaries, which can easily cause defect enrichment and stress concentration, reducing material density and thus lowering performance. E b These contradictions make it difficult to balance compactness and breakdown performance by relying solely on grain boundary engineering.

[0004] To alleviate these problems, some technologies attempt to create structural heterogeneity at the microscale. For example, by introducing an insulating second phase to fill the voids between particles or to coat the matrix grains, local electric field concentration can be reduced and breakdown path propagation suppressed, thereby improving... E b However, since the dielectric constant of this type of second-phase material is usually lower than that of the parent perovskite, its introduction often leads to a maximum polarization intensity ( P m The decline in energy storage capacity can negatively impact energy storage performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a self-assembled multiphase core-shell structure lead-free dielectric energy storage ceramic material and its preparation method, solving the technical problem in the prior art that it is difficult to simultaneously achieve the energy storage density, breakdown electric field and polarization intensity of lead-free dielectric materials.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing a self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material, comprising the following steps: S1, press (1- x )[(1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 )O3]- x (Bi 0.5 Na 0.5 The stoichiometric ratio of TiO3 was determined by mixing ceramic raw materials thoroughly to obtain a mixed raw material; where 0 < x <0.4, 0< y <1; S2, the mixed raw materials are pre-sintered, mixed by secondary ball milling, dried, sieved, granulated, pre-pressed and cold isostatically pressed to make ceramic green bodies; S3, ceramic green bodies are sintered and cooled to obtain lead-free dielectric energy storage ceramic materials.

[0007] Secondly, the present invention provides a lead-free dielectric energy storage ceramic material prepared by the above-mentioned preparation method.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes lead-free ferroelectric ceramic materials (1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 An appropriate amount of sodium bismuth titanate (Bi) is dissolved in an O3 matrix. 0.5 Na 0.5 After being formulated and sintered at high temperature, TiO3 basic elements spontaneously form a core-shell microstructure within the ceramic grains. The core is dominated by the BaTiO3 ferroelectric phase, while the shell is dominated by a multiphase, weakly polar relaxor phase. This core-shell microstructure promotes a simultaneous increase in the material's polarization intensity and breakdown electric field. Therefore, the energy storage performance of the lead-free dielectric energy storage ceramic material prepared by this invention is significantly improved at room temperature, achieving a recoverable energy storage density of up to 6.5 J / cm³. The lead-free dielectric energy storage ceramic material prepared by this invention possesses high energy storage density, high breakdown electric field, and high polarization intensity, while also exhibiting simple processing and low cost. Attached Figure Description

[0009] Figure 1These are SEM images of the lead-free dielectric energy storage ceramic materials prepared in Comparative Example 1 and Examples 1-4 of the present invention; wherein, (a) is Comparative Example 1, (b) is Example 1, (c) is Example 2, (d) is Example 3, and (e) is Example 4. Figure 2 This is a TEM image of the lead-free dielectric energy storage ceramic material in Embodiment 2 of the present invention; Figure 3 This is the hysteresis loop diagram of the lead-free dielectric energy storage ceramic material in Embodiment 2 of the present invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] To simultaneously increase the energy storage density of the material ( W rec ), breakdown electric field ( E b ) and maximum polarization intensity ( P m This invention provides a self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material and its preparation method. Through component design, material preparation, and high-temperature sintering, a core-shell self-assembled structure is formed, combining a highly polar or highly ferroelectric core with a relaxor shell, which not only improves... P m It can also make the internal electric field distribution more uniform and improve... E b This allows for the achievement of higher recoverable energy density. The present invention provides a feasible approach to improve the overall performance of lead-free dielectric energy storage materials.

[0012] Specifically, this invention employs a microstructure control strategy, through the use of lead-free ferroelectric ceramic materials (1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 Sodium bismuth titanate (Bi) dissolved in O3 0.5 Na 0.5 TiO3 basic elements affect the diffusion behavior of various elements in ceramics during high-temperature sintering, causing the spontaneous formation of core-shell microstructures with strong polarization nuclei and weak relaxation shells inside the ceramic grains, which synergistically improves the polarization intensity and breakdown electric field of the ceramic material.

[0013] In a first aspect, the present invention provides a method for preparing a self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material, comprising the following steps: S1, press (1- x )[(1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 )O3]- x (Bi 0.5 Na 0.5 The stoichiometric ratio of TiO3 was determined by mixing ceramic raw materials thoroughly to obtain a mixed raw material; where 0 < x <0.4, 0< y <1; S2, the mixed raw materials are pre-sintered, mixed by secondary ball milling, dried, sieved, granulated, pre-pressed and cold isostatically pressed to make ceramic green bodies; S3, ceramic green bodies are sintered and cooled to obtain lead-free dielectric energy storage ceramic materials.

[0014] This invention is based on (1- x )[(1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 )O3]- x (Bi 0.5 Na 0.5 The dosage of TiO3 is prepared according to its stoichiometric ratio, wherein... x , y It is the molar mass ratio, and x When the temperature is too high, the energy storage efficiency of the material will drop sharply. y When the polarization intensity is too high, the polarization intensity of the material will decrease. The preparation method of the present invention is simple, and the resulting lead-free dielectric energy storage ceramic material has a core-shell microstructure and simultaneously possesses high polarization intensity, high breakdown electric field and high energy storage density.

[0015] Preferably, in step S1, the ceramic raw materials include BaCO3, ZrO2, TiO2, Bi2O3, ZnO, Ta2O5, and Na2CO3.

[0016] Preferably, in step S1, 0.1 ≤ x ≤0.3, 0.1≤ y ≤0.2.

[0017] Preferably, in step S1, the ceramic raw materials are ball-milled and mixed evenly, and then dried to obtain the mixed raw materials.

[0018] Further preferred, the ball milling conditions include: using zirconium balls as the ball milling medium and anhydrous ethanol as the ball milling solvent, wherein the mass ratio of the ball milling medium, the ball milling solvent and the ceramic raw material is 20:(1-10):(1-10), and the ball milling time is 0.5-24h.

[0019] Further preferred drying conditions are: drying at 40–100 °C for 0.5–24 hours.

[0020] It is understandable that the secondary ball milling and subsequent drying in step S2 can be performed under the same conditions as the ball milling and drying in step S1.

[0021] Preferably, in step S2, the pre-sintering is carried out by heating to 600-1200 ℃ at a heating rate of 2-20 ℃ / min and holding at that temperature for 0.5-24 hours. If the pre-sintering temperature is too high, the block will be too hard, and the secondary ball milling will not be able to break the block into fine particles. If the pre-sintering temperature is too low, the block will not be able to form the required pure perovskite structure.

[0022] Preferably, in step S2, the sieving is done through a 10-300 mesh sieve, and the material passing through the sieve is collected.

[0023] Preferably, in step S2, the granulation step includes: adding a binder to the sieved powder and then granulating, wherein the amount of binder is 2-30% of the mass of the sieved powder; the binder is an aqueous solution of polyvinyl alcohol with a mass concentration of 1-20%. If the amount of binder is too high, more pores will be left when the binder is discharged, which is not conducive to improving the density of the ceramic.

[0024] Preferably, in step S2, the pre-compression pressure is between 1 and 10 MPa, and the pressure is maintained for 5 to 60 seconds.

[0025] Preferably, in step S2, the pressure of the cold isostatic pressing is 100-300 MPa, and the pressure is maintained for 50-150 seconds.

[0026] Preferably, in step S3, the sintering temperature is 1000–1400 °C and the time is 1–24 h. If the sintering temperature is too high or the time is too long, the grains will grow too large, which is not conducive to improving the breakdown electric field. If the sintering temperature is too low or the time is too short, the bulk material will not be able to be ceramicized.

[0027] More preferably, the sintering heating rate is 2–20 °C / min.

[0028] Secondly, the present invention provides a lead-free dielectric energy storage ceramic material prepared by the above-mentioned preparation method.

[0029] The lead-free dielectric energy storage ceramic material prepared by this invention has a core-shell microstructure and high polarization intensity (38 μC / cm).2 High breakdown electric field (490 kV / cm) and high energy storage density (up to 6.5 J / cm²) 3 ), suitable for making pulse power devices.

[0030] The present invention will be further described in detail below through specific embodiments.

[0031] Comparative Example 1 Preparation of 0.85Ba(Zr) 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 O3 lead-free dielectric energy storage ceramic material, including the following steps: S1, according to the stoichiometric ratio, weigh 0.15 mol of 0.85 mol of Ba(Zr) 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 The required raw materials, namely BaCO3 (25.22 g), ZrO2 (1.59 g), TiO2 (9.17 g), Bi2O3 (5.26 g), ZnO (1.23 g), and Ta2O5 (1.66 g), were prepared according to the specified amounts. All raw materials were mixed evenly using a wet ball milling process. The mass ratio of the ball milling media, anhydrous ethanol, and ball milling material was 8:4:3. The ball milling time was 24 hours. The ball milling media was zirconium balls, and the ball milling solvent was anhydrous ethanol. The mixture was then dried to obtain the mixed raw materials.

[0032] S2, the mixed raw materials obtained in step S1 are pre-fired at 850 ℃ for 3 hours; the pre-fired material is ball-milled again for 24 hours to obtain ceramic powder, which is then passed through an 80-mesh sieve. 10% of the mass of the sieved ceramic powder is added as a binder for granulation. The binder is a 4% polyvinyl alcohol aqueous solution. The resulting granules are pre-pressed at a pressure of 4 MPa for 10 seconds. Then, they are cold isostatically pressed to obtain ceramic green bodies at a pressure of 200 MPa for 90 seconds.

[0033] S3, the ceramic green body obtained in step S2 is sintered in air: the temperature is raised to 1200℃ at a rate of 3℃ / min and held for 2 hours, then cooled to room temperature in the furnace to obtain 0.85Ba(Zr) 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 O3 lead-free dielectric energy storage ceramic material.

[0034] SEM images of the obtained lead-free dielectric energy storage ceramic material are as follows: Figure 1 As shown in (a).

[0035] Example 1 Preparation of 0.9[0.85Ba(Zr)] 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]-0.1(Bi 0.5 Na 0.5 TiO3 lead-free dielectric energy storage ceramic material, including the following steps: S1, according to the stoichiometric ratio, weigh 0.15 mol of 0.9[0.85Ba(Zr)] 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3Ta 1 / 3 )O3]-0.1(Bi 0.5 Na 0.5 The raw materials required for TiO3, namely BaCO3 (22.70 g), ZrO2 (1.43 g), TiO2 (9.46 g), Bi2O3 (6.48 g), ZnO (1.11 g), Ta2O5 (1.49 g), and Na2CO3 (0.40 g), were prepared in the specified amounts. All raw materials were mixed evenly using a wet ball milling process. The mass ratio of the ball milling media, anhydrous ethanol, and ball milling material was 8:4:3. The ball milling time was 24 hours. The ball milling media was zirconium balls, and the ball milling solvent was anhydrous ethanol. The mixture was then dried to obtain the mixed raw materials.

[0036] S2, the mixed raw materials obtained in step S1 are pre-fired at 850 ℃ for 3 hours; the pre-fired material is ball-milled again for 24 hours to obtain ceramic powder, which is then passed through an 80-mesh sieve. 10% of the mass of the sieved ceramic powder is added as a binder for granulation. The binder is a 4% polyvinyl alcohol aqueous solution. The resulting granules are pre-pressed at a pressure of 4 MPa for 10 seconds. Then, they are cold isostatically pressed to obtain ceramic green bodies at a pressure of 200 MPa for 90 seconds.

[0037] S3, the ceramic green body obtained in step S2 is sintered in air: the temperature is raised to 1200℃ at a rate of 3℃ / min and held for 2 hours, then cooled to room temperature in the furnace to obtain 0.9[0.85Ba(Zr)]. 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]-0.1(Bi 0.5 Na 0.5 TiO3 lead-free dielectric energy storage ceramic material.

[0038] SEM images of the obtained lead-free dielectric energy storage ceramic material are as follows: Figure 1 As shown in (b).

[0039] Example 2 Compared with Example 1, the only difference is that the raw material ratio in step S1 is adjusted to prepare 0.8[0.85Ba(Zr)] 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]-0.2(Bi 0.5 Na 0.5 The TiO3 lead-free dielectric energy storage ceramic material was prepared using the same steps and conditions as in Example 1. The specific differences are as follows: S1: Weigh 0.15 mol of 0.8[0.85Ba(Zr) according to the stoichiometric ratio. 0.1 Ti 0.9 )O3- 0.15Bi(Zn 2 / 3Ta 1 / 3 )O3]-0.2(Bi 0.5 Na 0.5 The raw materials required for TiO3, namely BaCO3 (20.18 g), ZrO2 (1.27 g), TiO2 (9.74 g), Bi2O3 (7.71 g), ZnO (0.98 g), Ta2O5 (1.33 g) and Na2CO3 (0.80 g), were prepared in the specified amounts and mixed evenly using a wet ball milling process.

[0040] SEM images of the obtained lead-free dielectric energy storage ceramic material are as follows: Figure 1 As shown in (c), the TEM image is as follows: Figure 2 As shown, the hysteresis loop at room temperature is as follows Figure 3 As shown.

[0041] Example 3 Compared with Example 1, the only difference is that the raw material ratio in step S1 is adjusted to prepare 0.7[0.85Ba(Zr)] 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]-0.3(Bi 0.5 Na 0.5 The TiO3 lead-free dielectric energy storage ceramic material was prepared using the same steps and conditions as in Example 1. The specific differences are as follows: S1: Weigh 0.15 mol of 0.7[0.85Ba(Zr) according to the stoichiometric ratio. 0.1 Ti 0.9 )O3- 0.15Bi(Zn 2 / 3Ta 1 / 3 )O3]-0.3(Bi0.5 Na 0.5 The required raw materials for TiO3, namely BaCO3 (17.65 g), ZrO2 (1.11 g), TiO2 (10.02 g), Bi2O3 (8.94 g), ZnO (0.86 g), Ta2O5 (1.16 g) and Na2CO3 (1.19 g), were prepared in the specified amounts and mixed evenly using a wet ball milling process.

[0042] SEM images of the obtained lead-free dielectric energy storage ceramic material are as follows: Figure 1 As shown in (d).

[0043] Comparative Example 2 Compared with Example 1, the only difference is that the raw material ratio in step S1 is adjusted to prepare 0.6[0.85Ba(Zr)] 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]-0.4(Bi 0.5 Na 0.5 The TiO3 lead-free dielectric energy storage ceramic material was prepared using the same steps and conditions as in Example 1. The specific differences are as follows: S1: Weigh 0.15 mol of 0.6 [0.85 Ba(Zr) according to the stoichiometric ratio. 0.1 Ti 0.9 )O3- 0.15Bi(Zn 2 / 3Ta 1 / 3 )O3]-0.4(Bi 0.5 Na 0.5 The raw materials required for TiO3, namely BaCO3 (15.13 g), ZrO2 (0.95 g), TiO2 (10.30 g), Bi2O3 (10.17 g), ZnO (0.74 g), Ta2O5 (0.99 g) and Na2CO3 (1.59 g), were prepared in the specified amounts and mixed evenly using a wet ball milling process.

[0044] SEM images of the obtained lead-free dielectric energy storage ceramic material are as follows: Figure 1 As shown in (e).

[0045] Comparative Example 3 The only difference from Example 2 is that Ba(Zr) is used instead of Zr. 0.1 Ti 0.9 Replace O3 with Ba(Zr) 0.2 Ti 0.8 O3, other steps and conditions are the same as in Example 2, the polarization intensity will decrease.

[0046] Comparative Example 4 Compared with Example 2, the only difference is that the pre-sintering temperature is 500°C, while the other steps and conditions are the same as in Example 2, and the material properties will degrade sharply.

[0047] Results Analysis Based on the test results Figure 1-3 It can be seen that the lead-free dielectric energy storage ceramic material of the present invention has the following characteristics: Depend on Figure 1 A comparison of SEM images of the lead-free dielectric energy storage ceramic materials obtained in Comparative Example 1 and Examples 1-4 shows that the materials obtained in Examples 1-4 were produced by solid-solution of an appropriate amount of sodium bismuth titanate (Bi). 0.5 Na 0.5 TiO3 basic unit, with x As the crystal size increases, the resulting ceramic material first decreases and then increases, and all samples have a dense and uniform grain structure.

[0048] Figure 2 The image shows a TEM image of the lead-free dielectric energy storage ceramic material in Example 2. The results indicate that a core-shell microstructure spontaneously forms within the ceramic grains. Furthermore, in the core-shell microstructure of this invention, the core is dominated by the BaTiO3 ferroelectric phase, while the shell is dominated by a weakly polar relaxation phase with multiple coexisting phases. In contrast, Comparative Example 1 lacks sodium bismuth titanate (Bi). 0.5 Na 0.5 TiO3 basic units cannot form core-shell microstructures.

[0049] Figure 3 The hysteresis loop diagram of the lead-free dielectric energy storage ceramic material in Example 2 shows that: when x When y = 0.2 and y = 0.15, 0.8[0.85Ba(Zr) 0.1 Ti 0.9 )O3-0.15Bi(Zn 2 / 3 Ta 1 / 3 )O3]- 0.2(Bi 0.5 Na 0.5 The TiO3 ceramic material exhibits superior performance compared to other embodiments and comparative examples, possessing high polarization intensity (38 μC / cm). 2 High breakdown electric field (490 kV / cm) and high energy storage density (6.5 J / cm²). 3 It is particularly suitable for manufacturing pulsed power devices. Furthermore, with... x As the polarization intensity increases, the breakdown electric field first increases and then decreases, as shown in Table 1 below.

[0050] Table 1 Test results of Examples 1-4 and Comparative Example 1

[0051] As shown in Table 1, the polarization intensity of Comparative Example 1 is low, which also proves that the present invention achieves this by solid-solution of an appropriate amount of sodium bismuth titanate (Bi). 0.5 Na 0.5 The advantages of TiO3 units in forming core-shell microstructures; meanwhile, as shown in Comparative Example 2, sodium bismuth titanate (Bi 0.5 Na 0.5 The amount of TiO3 monomers dissolved in the solution is not necessarily better the higher it is, as excessive amounts can lead to a sharp decrease in the breakdown electric field; therefore, the preferred amount in this invention is 0.1 ≤ x ≤0.3, more preferably 0.1≤ x ≤0.2.

[0052] In summary, this invention provides a method for improving the energy storage performance of lead-free ferroelectric ceramic materials, specifically in lead-free relaxor ferroelectric ceramic materials (1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 Introducing sodium bismuth titanate (Bi) into O3 0.5 Na 0.5 TiO3 basic elements, after being formulated and sintered at high temperature using a solid-state method, spontaneously formed a core-shell microstructure within the resulting ceramic grains. Experimental results show that a stable core-shell microstructure was generated in the material, and this microstructure enhances the polarization behavior of the material and significantly increases the breakdown electric field, thereby achieving a higher recoverable energy storage density. Under an electric field of 490 kV / cm, the prepared lead-free dielectric energy storage ceramic achieved 6.5 J / cm. 3 This invention provides a new approach to the design of high-energy-density lead-free dielectric energy storage ceramic materials by constructing a core-shell microstructure, achieving recoverable energy storage density.

[0053] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material, characterized in that, Includes the following steps: S1, press (1- x )[(1- y )Ba(Zr 0.1 Ti 0.9 O3- y Bi(Zn 2 / 3 Ta 1 / 3 )O3]- x (Bi 0.5 Na 0.5 The stoichiometric ratio of TiO3 was determined by mixing ceramic raw materials thoroughly to obtain a mixed raw material; where 0 < x <0.4, 0< y <1; S2, the mixed raw materials are pre-sintered, mixed by secondary ball milling, dried, sieved, granulated, pre-pressed and cold isostatically pressed to make ceramic green bodies; S3, ceramic green bodies are sintered and cooled to obtain lead-free dielectric energy storage ceramic materials.

2. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S1, the ceramic raw materials include BaCO3, ZrO2, TiO2, Bi2O3, ZnO, Ta2O5, and Na2CO3.

3. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S1, 0.1 ≤ x ≤0.3, 0.1≤ y ≤0.

2.

4. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S1, the ceramic raw materials are ball-milled and mixed evenly, and then dried to obtain a mixed raw material; The ball milling conditions include: using zirconium balls as the ball milling medium and anhydrous ethanol as the ball milling solvent, wherein the mass ratio of the ball milling medium, the ball milling solvent and the ceramic raw material is 20:(1~10):(1~10), and the ball milling time is 0.5~24 h; The drying conditions are: drying at 40–100 °C for 0.5–24 hours.

5. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S2, the pre-sintering is carried out by heating to 600-1200 ℃ at a heating rate of 2-20 ℃ / min and holding at that temperature for 0.5-24 hours.

6. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S2, the sieving involves passing the material through a 10-300 mesh sieve and collecting the material passing through the sieve. The granulation step includes: adding a binder to the sieved powder and then granulating it, wherein the amount of binder is 2-30% of the mass of the sieved powder; the binder is an aqueous solution of polyvinyl alcohol with a mass concentration of 1-20%.

7. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S2, the pressure of the pre-compression molding is between 1 and 10 MPa, and the pressure is maintained for 5 to 60 seconds; The pressure of the cold isostatic pressing is 100–300 MPa, and the pressure is maintained for 50–150 seconds.

8. The method for preparing the self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 1, characterized in that, In step S3, the sintering temperature is 1000–1400 °C and the time is 1–24 h.

9. The method for preparing a self-assembled multiphase core-shell structured lead-free dielectric energy storage ceramic material according to claim 8, characterized in that, In step S3, the heating rate of the sintering is 2 to 20 °C / min.

10. Lead-free dielectric energy storage ceramic material prepared by the preparation method according to any one of claims 1-9.

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