A high energy storage antiferroelectric modified BiFeO3-BaTiO3 ceramic and a preparation method thereof

Abstract

The application relates to a kind of antiferromagnetic modified high-energy-storage BiFeO3-BaTiO3 ceramic and a preparation method thereof.The ceramic material prepared in the application is green lead-free, and the cost is low and controllable, the ceramic has the characteristics of high density, grain refinement and high breakdown field at room temperature, and after adding ANT, the ceramic has the characteristics of high density, grain refinement and high breakdown field.The sintering method used in the application reduces the sintering temperature, and the ceramic is dense and grain refinement.

Description

Technical Field

[0001] This invention belongs to the field of functional ceramic materials technology, specifically relating to an antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic and its preparation method. Background Technology

[0002] With the continuous depletion of fossil fuels and natural resources, energy shortages and environmental pollution have become major concerns in society. At the same time, the development of clean energy (such as solar and wind power) has spurred research into novel energy storage devices. Dielectric capacitors are an important type of electrical energy storage device. Compared to other existing energy storage devices (such as batteries, fuel cells, and electrochemical capacitors), dielectric capacitors offer advantages such as high power density, fast charging / discharging, and high reliability. They are widely used in consumer electronics, hybrid vehicles, advanced medical equipment, and power systems, becoming key components in electronic devices and pulse power systems.

[0003] The energy storage performance of dielectric capacitors depends primarily on the dielectric material used. Compared to polymer materials, ceramic dielectric materials exhibit superior thermal stability, frequency stability, and mechanical stability, making them more reliable under extreme conditions. Lead-based ceramics, such as PbZrO3, (Pb,La)(Zr,Ti)O3, (Pb,La)(Zr,Sn,Ti)O3, and (Pb,La)(Zr,Sn)O3, have been applied to high-power pulse capacitors due to their excellent energy storage performance. However, the use of lead has brought environmental problems, and its toxicity is harmful to human health. AgNbO3 possesses unique characteristics such as a double hysteresis loop, high saturation polarization, and high Curie temperature, making it a hot topic in lead-free antiferroelectric ceramic research. However, its poor temperature stability and high cost limit its application in the energy storage field. Bismuth ferrite (BiFeO3) has a high saturation polarization (100 μC / cm). 3 Its low cost and green, pollution-free characteristics have attracted increasing attention in the field of energy storage.

[0004] Reference 1 (Ji, Shuaishuai et al., J. Am. Ceram. Soc. 104. 6 (2021)) reports the synthesis of (1-x)BiFeO3-x(0.85BaTiO3-0.15Bi(Sn) by solid-state method. 0.5 Zn 0.5 O3) perovskite structure ceramics with a storage density of 3.06 J / cm³ 3 Reference 2 (Wang, Wei et al., ACS Appl. Energy Mater. 4.9 (2021)) reported SrTiO3-doped BiFeO3-BaTiO3 relaxor ferroelectric ceramics with a storage efficiency as high as 95.55% and a storage density of 2.13 J / cm³.3 .

[0005] The trend towards miniaturization, lightweighting, and integration of energy storage devices places higher demands on the breakdown strength, energy density, and energy storage efficiency of energy storage materials. Currently, the energy density of bismuth ferroelectric ceramics is <4 J / cm³. 3 With relatively low efficiency (<80%), it is difficult to meet the development needs of future energy storage devices. Therefore, it is becoming increasingly important to develop lead-free energy storage ceramics with higher performance. Summary of the Invention

[0006] To address the problems of lead contamination, high cost, and low energy density in existing dielectric energy storage ceramics, this invention aims to provide an antiferroelectric modified high-energy-density BiFeO3-BaTiO3 ceramic and its preparation method. This lead-free BiFeO3-BaTiO3 ceramic exhibits high energy density, with a recoverable energy density reaching up to 7.0 J / cm³. 3 It is inexpensive and environmentally friendly.

[0007] According to one aspect of the present invention, an antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic is provided, the general chemical formula of which is: (0.67-x)BiFeO3-0.33BaTiO3-xAg(Nb) 0.85 Ta 0.15 O3, of which 0 <x≤0.15。

[0008] In this invention, considering the high leakage current of pure BiFeO3, highly insulating BaTiO3 is added to form quasi-in-phase boundaries (MPBs) to improve the ferroelectric properties and breakdown resistance of the material. The antiferroelectric phase Ag(Nb) 0.85 Ta 0.15 The role of O3 (ANT) is to reduce the remanent polarization of the material, forming a relaxor ferroelectric. In addition, the low-valence ions (Ag) at the A site... + ) and high-valence ions at the B site (Nb 5+ / Ta 5+ Partial substitution helps optimize the sintering behavior of BiFeO3-based ceramics and reduce leakage current.

[0009] According to one embodiment of the present invention, 0.05 ≤ x ≤ 0.15.

[0010] According to one embodiment of the present invention, 0.08 ≤ x ≤ 0.12.

[0011] According to one embodiment of the present invention, 0.09 ≤ x ≤ 0.11.

[0012] According to one embodiment of the present invention, x = 0.1.

[0013] Under these conditions, ceramics exhibit excellent energy storage performance, with a recoverable energy storage density reaching up to 7.0 J / cm³. 3 It has an energy storage efficiency of 80.5% and excellent stability at different frequencies and temperatures.

[0014] According to one embodiment of the present invention, the recoverable energy storage density of the BiFeO3-BaTiO3-based lead-free energy storage ceramic is greater than 7 J / cm³. 3 The energy storage efficiency is greater than 80%.

[0015] According to one embodiment of the present invention, the recoverable energy storage density and efficiency of the BiFeO3-BaTiO3-based lead-free energy storage ceramic under an electric field of 300 kV / cm fluctuate by no more than 4% in the frequency range of 1 to 50 Hz and by no more than 9% in the temperature range of 20°C to 120°C.

[0016] According to another aspect of the invention, a dielectric capacitor is provided that uses the aforementioned antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic as the dielectric material.

[0017] According to another aspect of the invention, an energy storage device is provided, which includes the aforementioned dielectric capacitor.

[0018] According to another aspect of the present invention, a method for preparing the above-mentioned antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic is provided, the method comprising the following steps:

[0019] S1) Using Bi2O3, Fe2O3, BaCO3, TiO2, Ag2O, Ta2O5 and Nb2O5 as raw materials, after mixing them according to the stoichiometric ratio, anhydrous ethanol or isopropanol is added and the mixture is ball-milled once, and then dried to obtain a mixed dry powder.

[0020] S2) The mixed dry powder is pre-fired at 750-850℃ for 4-8 hours to obtain pre-fired powder;

[0021] S3) Add 0.05-0.2wt% MnO2 to the pre-calcined powder, and perform secondary ball milling with anhydrous ethanol or isopropanol, and then dry to obtain the treated pre-calcined powder;

[0022] S4) The pre-calcined powder after treatment is mixed with solvent, dispersant, plasticizer and binder and ball-milled three times to obtain slurry;

[0023] The solvent is selected from ethanol, ethyl acetate, and combinations thereof;

[0024] The dispersant is selected from trioleic acid glyceride, polyethylene glycol, and combinations thereof;

[0025] The plasticizer is dibutyl phthalate;

[0026] The adhesive is polyvinyl butyral;

[0027] S5) The slurry obtained in step S4) is coated onto the substrate by tape casting. After drying, the ceramic blank is peeled off from the substrate to obtain the ceramic blank.

[0028] S6) Press the ceramic blank obtained in step S5) using a warm isostatic press at 50-70℃ and 50-70MPa, then sinter at 500-700℃ for 3-8 hours. Next, raise the temperature to 950-1000℃ at a rate of 5-10℃ / min and hold for 1-5 minutes. Then lower the temperature to 850-900℃ at a rate of 20-30℃ / min and hold for 1-3 hours. Finally, cool to room temperature to obtain antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic.

[0029] According to one embodiment of the present invention, wherein,

[0030] The temperature mentioned in step S2) is 800℃, and the preheating time is 5-7 hours; and / or

[0031] Step S3) added 0.1 wt% MnO2; and / or

[0032] In step S4), the treated pre-calcined powder is mixed with polyvinyl butyral, ethanol, ethyl acetate, dibutyl phthalate, glyceryl trioleate, and polyethylene glycol and ball-milled to obtain a slurry; and / or

[0033] In step S6), the ceramic blank obtained in step S5) is pressed using a warm isostatic press at 60°C and 60MPa. Then, it is sintered at 600°C for 4 hours to remove organic matter. Next, the temperature is raised to 950-1000°C at a rate of 5°C / min and held for 1 minute. Then, the temperature is lowered to 900°C at a rate of 20°C / min and held for 2 hours. Finally, it is cooled to room temperature to obtain antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic.

[0034] According to one embodiment of the present invention, the method includes the following steps:

[0035] 1) Using Bi2O3, Fe2O3, BaCO3, TiO2, Ag2O, Ta2O5 and Nb2O5 as raw materials, the raw materials are thoroughly dried in a drying oven to remove moisture. The temperature of the drying oven is set to 80 to 100℃ and the time is 12 hours.

[0036] 2) Prepare the raw material powder obtained in step 1) according to the stoichiometric ratio;

[0037] 3) Mix the raw material powder prepared in step 2), anhydrous ethanol and zirconium oxide grinding balls in a nylon ball mill jar, and then ball mill it for 24 hours using a planetary ball mill to form a uniform mixture. The ball mill speed is 300 rpm.

[0038] 4) Place the mixture obtained in step 3) into a forced-air drying oven for drying, and control the drying temperature to be 80 to 100℃. Grind the obtained mixed dry powder evenly using a mortar and pestle, put the evenly mixed powder into a crucible and compact it, and then put it into a muffle furnace for pre-firing at 800℃ for 6 hours. After pre-firing, let it cool naturally to room temperature.

[0039] 5) Add 0.1wt% MnO2 to the pre-calcined powder obtained in step 4), and then perform a second ball milling with anhydrous ethanol as the medium. The ball mill speed is 300 rpm and the ball milling time is 24 hours.

[0040] 6) After the second ball milling is completed, put the pre-fired powder obtained in step 5) into a drying oven to dry. The drying temperature is controlled at 80-100℃. Use a mortar and pestle to grind the dried pre-fired powder evenly. The pre-fired powder preparation is now complete. Next, prepare the casting slurry.

[0041] 7) Mix the pre-calcined powder obtained in step 6) with polyvinyl butyral, ethanol, ethyl acetate, dibutyl phthalate, trioleic acid glyceride and polyethylene glycol, and ball mill for 12 hours at a speed of 100 rpm to obtain a uniform slurry.

[0042] 8) The slurry obtained in step 7) is coated onto the substrate by casting, and after drying, the ceramic blank is peeled off from the substrate.

[0043] 9) Press the ceramic blank obtained in step 8) using a warm isostatic press at 60℃ and 60MPa to obtain a dense ceramic blank.

[0044] 10) Sinter the dense ceramic blank obtained in step 9) at 600°C for 4 hours to remove organic matter;

[0045] 11) The blank discs obtained in step 10) are sintered into ceramics through the following process: the temperature is raised to 950℃~1000℃ at a rate of 5℃ / min, held for 1min, then rapidly cooled to 900℃ at a rate of 20℃ / min, held for 2h, and finally cooled to room temperature to obtain antiferroelectric modified high-energy BiFeO3-BaTiO3 ceramics.

[0046] The sintered ceramic sample has a thickness of approximately 40–50 μm. Pt electrodes with an area of ​​3.14 mm² were deposited on both surfaces of the ceramic sheet by sputtering. 2 .

[0047] Beneficial effects

[0048] The ceramic of this invention uses BiFeO3 as the matrix material, with the addition of BaTiO3 and a small amount of Ag(Nb) 0.85 Ta 0.15 O3 is synthesized through solid-state sintering, resulting in a green, lead-free material with low and controllable costs. The sintering method used in this invention lowers the sintering temperature and yields dense, grain-refined ceramics. The ceramics prepared by this invention exhibit a pseudo-tetragonal perovskite structure at room temperature. After adding ANT, the ceramics possess high density, refined grains, and a high breakdown electric field. Attached Figure Description

[0049] Figure 1 The XRD diffraction patterns are those of the ceramic samples prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0050] Figure 2 The images show surface SEM images of ceramic samples prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0051] Figure 3 The average grain size statistics are for the ceramic samples prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0052] Figure 4 Figures a, b, c, and d in the figure show the unipolar hysteresis loops of the ceramic samples prepared in Examples 1-3 and Comparative Example 1 of the present invention under the highest electric field.

[0053] Figure 5 The breakdown electric field statistics are shown for the ceramic samples prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0054] Figure 6 The energy storage density and energy storage efficiency of the ceramic samples prepared in Examples 1-3 and Comparative Example 1 of this invention are shown.

[0055] Figure 7 The changes in energy storage density and energy storage efficiency of the ceramic sample prepared in Example 2 of this invention at different frequencies.

[0056] Figure 8 The changes in energy storage density and energy storage efficiency of the ceramic sample prepared in Example 2 of this invention at different temperatures. Detailed Implementation

[0057] To make the objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0058] The raw materials and instruments used in the following text are shown in the table below.

[0059] raw material Manufacturer Sales Company purity <![CDATA[Bi2O3]]> Aladdin Sinopharm Chemical Reagents Beijing Co., Ltd. 99.9％ <![CDATA[Fe2O3]]> Aladdin Sinopharm Chemical Reagents Beijing Co., Ltd. 99.5％ <![CDATA[BaCO3]]> Myriel Shanghai Myriel Chemical Technology Co., Ltd. 99％ <![CDATA[TiO2]]> Myriel Shanghai Myriel Chemical Technology Co., Ltd. 99％ <![CDATA[Ag2O]]> Myriel Shanghai Myriel Chemical Technology Co., Ltd. 99％ <![CDATA[Ta2O5]]> Aladdin Beijing Mairuida Technology Co., Ltd. 99.9％ <![CDATA[Nb2O5]]> Aladdin Beijing Lanyi Chemical Products Co., Ltd. 99.9％ <![CDATA[MnO2]]> Myriel Shanghai Myriel Chemical Technology Co., Ltd. 99％

[0060]

[0061]

[0062] Example 1:

[0063] The chemical formula is: 0.62BiFeO3-0.33BaTiO3-0.05Ag(Nb) 0.85 Ta 0.15 O3 (x = 0.05)

[0064] The raw materials used are Bi2O3, Fe2O3, BaCO3, TiO2, Ag2O, Ta2O5, and Nb2O5, and the purity of all raw materials should be higher than 99%.

[0065] Specifically, the following steps are included:

[0066] 1) All raw materials are thoroughly dried in a drying oven to remove moisture. The temperature of the drying oven is set to 90℃ and the time is 12 hours.

[0067] 2) The raw material powder obtained in step 1) is mixed according to the stoichiometric ratio.

[0068] 3) Mix the raw material powder prepared in step 2), anhydrous ethanol and zirconium oxide grinding balls in a nylon ball mill jar, and then ball mill for 24 hours using a planetary ball mill to form a uniform mixture. The ball mill speed is 300 rpm.

[0069] 4) Place the mixture obtained in step 3) into a forced-air drying oven for drying at a temperature of 90°C. Grind the resulting dry powder evenly using a mortar and pestle. Place the evenly mixed powder into a crucible, compact it, and then place it in a muffle furnace for pre-firing at 800°C for 6 hours. After pre-firing, allow it to cool naturally to room temperature.

[0070] 5) Add 0.1 wt% MnO2 to the pre-calcined powder obtained in step 4), and then perform a second ball milling with anhydrous ethanol as the medium. The ball mill speed is 300 rpm and the ball milling time is 24 hours.

[0071] 6) After the second ball milling is completed, place the pre-calcined powder obtained in step 5) into a drying oven to dry at a temperature of 90°C. Grind the dried pre-calcined powder evenly using a mortar and pestle. The pre-calcined powder preparation is now complete. Next, prepare the casting slurry.

[0072] 7) Mix the pre-calcined powder obtained in step 6) with polyvinyl butyral, ethanol, ethyl acetate, dibutyl phthalate, trioleic acid glyceride and polyethylene glycol, and ball mill for 12 hours at a speed of 100 rpm to obtain a uniform slurry.

[0073] In this mixture, polyvinyl butyral is used as a binder, ethanol and ethyl acetate are used as solvents, dibutyl phthalate is used as a plasticizer, and trioleic acid glyceride and polyethylene glycol are used as dispersants. The content of these reagents is not particularly limited, as long as they can be mixed with the pre-calcined powder and ball-milled to obtain a slurry suitable for casting.

[0074] 8) The slurry obtained in step 7) is coated onto the substrate by casting, and after drying, the ceramic blank is peeled off from the substrate.

[0075] 9) Press the ceramic blank obtained in step 8) using a warm isostatic press at 60℃ and 60MPa to obtain a dense ceramic blank, and then cut the ceramic blank into round pieces with a diameter of 6-10mm.

[0076] 10) The blank discs obtained in step 9) are sintered at 600°C for 4 hours to remove organic matter.

[0077] 11) The ceramic wafer obtained in step 10) was sintered using the following process: the temperature was raised to 950°C at a rate of 5°C / min, held for 1 min, then rapidly cooled to 900°C at a rate of 20°C / min, held for 2 h, and finally allowed to cool naturally to room temperature. The thickness of the sintered ceramic sample was approximately 40–50 μm. Pt electrodes with an electrode area of ​​3.14 mm² were deposited on both surfaces of the ceramic wafer by sputtering. 2 .

[0078] Example 2:

[0079] The chemical formula of the energy storage ceramic is: 0.57BiFeO3-0.33BaTiO3-0.1Ag(Nb) 0.85 Ta 0.15 O3 (x = 0.1)

[0080] Compared with Example 1, the sintering parameters in step (11) were replaced as follows: the temperature was raised to 980°C at a rate of 5°C / min, held for 1 min, then rapidly cooled to 900°C at a rate of 20°C / min, held for 2 h, and finally naturally cooled to room temperature. Other conditions remained unchanged.

[0081] Example 3:

[0082] The chemical formula of the energy storage ceramic is: 0.52BiFeO3-0.33BaTiO3-0.15Ag(Nb) 0.85 Ta 0.15 O3 (x = 0.15)

[0083] Compared with Example 1, the sintering parameters in step (11) were replaced as follows: the temperature was raised to 1000°C at a rate of 5°C / min, held for 1 min, then rapidly cooled to 900°C at a rate of 20°C / min, held for 2 h, and finally naturally cooled to room temperature. Other conditions remained unchanged.

[0084] Comparative Example 1:

[0085] The chemical formula of the energy storage ceramic is: 0.67BiFeO3-0.33BaTiO3 (x=0)

[0086] The preparation process is the same as in Example 1.

[0087] Experimental Example 1: Structural Morphology Characterization

[0088] The X-ray diffraction patterns of the ceramics of Examples 1-3 and Comparative Example 1 were measured using a D8 Advance X-ray diffractometer from Bruker AXS GmbH.

[0089] Surface scanning electron microscope images of ceramics from Examples 1-3 and Comparative Example 1 were measured using a Zeiss Merlin Compact scanning electron microscope.

[0090] The average grain size of the ceramics in Examples 1-3 and Comparative Example 1 was analyzed based on the images from scanning electron microscopes.

[0091] Figure 1 These are the X-ray diffraction (XRD) patterns of the energy storage ceramics prepared in Examples 1-3 and Comparative Example 1 of this invention. As can be seen from the figures, all ceramics exhibit a perovskite pseudo-tetragonal phase structure.

[0092] Figure 2 These are scanning electron microscope (SEM) images of the energy storage ceramic surfaces prepared in Examples 1-3 and Comparative Example 1 of this invention. The ceramic in Comparative Example 1 exhibits significant pores and a relatively large grain size, averaging 2.39 μm. In Examples 1-3, due to the addition of ANT, the ceramic grains are very dense, with no significant pores observed, and the grain size is reduced to below 1 μm. This demonstrates that ANT can improve the density of the material while refining the grain size.

[0093] Figure 3 This is a statistical chart of the average grain size of the energy storage ceramics prepared in Examples 1-3 and Comparative Example 1 of the present invention. In the chart, the points where x is 0, 0.05, 0.10, and 0.15 correspond to Comparative Example 1 and Examples 1-3, respectively. It can be seen that as the ANT content increases, the grain size of the material first decreases and then increases, reaching a minimum value of 0.62 μm when x = 0.1. The relevant results of grain size are listed in Table 1 below.

[0094] Experiment Example 2: Electrical Performance Analysis

[0095] The hysteresis loop of ceramic samples was measured using a TF Analyzer 1000 ferroelectric analyzer from aixACCT GmbH, Germany.

[0096] The recoverable storage density (W) of the ceramic samples prepared in Examples 1-3 and Comparative Example 1, respectively. rec The energy storage efficiency (η) is measured and calculated. Calculation method:

[0097]

[0098]

[0099] The calculation results are shown in Table 1.

[0100] Table 1 shows the performance parameters of the energy storage ceramics prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0101]

[0102] More specifically, Figures 4-8 The measurements are of the hysteresis loop and energy storage performance of the energy storage ceramics prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0103] from Figure 4 As can be seen, the energy storage ceramics prepared in Examples 1-3 exhibit typical characteristics of relaxor ferroelectrics. Due to the reduction in remanent polarization, their hysteresis loops become longer and thinner, resulting in a significant improvement in energy storage density and efficiency. Simultaneously, the addition of ANT significantly enhances the ceramic breakdown electric field. In contrast, the energy storage ceramic prepared in Comparative Example 1 has a much lower breakdown electric field.

[0104] from Figure 5 It can be seen that when x = 0.05, the breakdown field strength (E) of the ceramic material is... b The breakdown field strength of the ceramic material is 323.5 kV / cm when x = 0.1; and 432.2 kV / cm when x = 0.15.

[0105] The recoverable energy storage density (W) of the energy storage ceramics prepared in Examples 1-3 rec The efficiency (η) is shown in Table 1 and Figure 6 As shown, at x = 0.05, the recoverable energy storage density and efficiency of the ceramic material are 3.83 J / cm³. 3 At x = 0.1, the recoverable energy storage density and efficiency of the ceramic material are 7.04 J / cm³, respectively. 3 At x = 0.15, the recoverable energy storage density and efficiency of the ceramic material are 3.84 J / cm³, respectively, with a recovery rate of 80.53%. 3And 84.76%.

[0106] Furthermore, the energy storage ceramic prepared in Example 2 exhibits the following stability: Figure 7 and Figure 8 As shown, when x = 0.1, the recoverable energy storage density and efficiency (300 kV / cm electric field) of the BiFeO3-BaTiO3-based lead-free energy storage ceramic fluctuates by no more than 4% in the frequency range of 1–50 Hz; and the recoverable energy storage density and efficiency (300 kV / cm electric field) fluctuates by no more than 9% in the frequency range of 20℃–120℃. This indicates that the energy storage ceramic has excellent frequency and temperature stability.

Claims

1. A high-energy-storage BiFeO3-BaTiO3 ceramic modified with antiferroelectric properties, having the general chemical formula: (0.67-x)BiFeO3-0.33BaTiO3-xAg(Nb) 0.85 Ta 0.15 )O3, where 0.05≤x≤0.

15.

2. The ceramic according to claim 1, wherein, x = 0.1。 3. The ceramic according to claim 2, wherein, The recoverable energy storage density of the BiFeO3-BaTiO3-based lead-free energy storage ceramic is greater than 7 J / cm³. 3 The energy storage efficiency is greater than 80%.

4. The ceramic according to claim 2, wherein, The recoverable energy storage density and efficiency of the BiFeO3-BaTiO3-based lead-free energy storage ceramic under an electric field of 300 kV / cm fluctuate by no more than 4% in the frequency range of 1 to 50 Hz and by no more than 9% in the temperature range of 20°C to 120°C.

5. A dielectric capacitor, wherein the dielectric capacitor uses antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic as the dielectric material according to any one of claims 1-4.

6. An energy storage device comprising the dielectric capacitor of claim 5.

7. A method for preparing antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramics according to any one of claims 1-4, the method comprising the following steps: S1) Using Bi2O3, Fe2O3, BaCO3, TiO2, Ag2O, Ta2O5 and Nb2O5 as raw materials, after mixing them according to the stoichiometric ratio, anhydrous ethanol or isopropanol is added and the mixture is ball-milled once, and then dried to obtain a mixed dry powder. S2) The mixed dry powder is pre-fired at 750-850°C for 4-8 hours to obtain pre-fired powder; S3) Add 0.05-0.2 wt% MnO2 to the pre-calcined powder, and perform secondary ball milling with anhydrous ethanol or isopropanol, and then dry to obtain the treated pre-calcined powder; S4) The pre-calcined powder after treatment is mixed with solvent, dispersant, plasticizer and binder and ball-milled three times to obtain slurry; The solvent is selected from ethanol, ethyl acetate, and combinations thereof; The dispersant is selected from trioleic acid glyceride, polyethylene glycol, and combinations thereof; The plasticizer is dibutyl phthalate; The adhesive is polyvinyl butyral; S5) The slurry obtained in step 4) is coated onto the substrate by tape casting. After drying, the ceramic blank is peeled off from the substrate to obtain the ceramic blank. S6) Press the ceramic blank obtained in step S5) using a warm isostatic press at 50-70°C and 50-70 MPa, then sinter at 500-700°C for 3-8 hours. Next, raise the temperature to 950-1000°C at a rate of 5-10°C / min and hold for 1-5 minutes. Then lower the temperature to 850-900°C at a rate of 20-30°C / min and hold for 1-3 hours. Finally, cool to room temperature to obtain antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic.

8. The method according to claim 7, wherein, The temperature mentioned in step S2) is 800°C, and the preheating time is 5-7 hours; and / or Step S3) 0.1 wt% MnO2 was added; and / or In step S4), the treated pre-calcined powder is mixed with polyvinyl butyral, ethanol, ethyl acetate, dibutyl phthalate, glyceryl trioleate, and polyethylene glycol and ball-milled to obtain a slurry; and / or In step S6), the ceramic blank obtained in step S5) is pressed using a warm isostatic press at 60°C and 60 MPa. Then, it is sintered at 600°C for 4 hours to remove organic matter. Next, the temperature is raised to 950-1000°C at a rate of 5°C / min and held for 1 minute. Then, the temperature is lowered to 900°C at a rate of 20°C / min and held for 2 hours. Finally, it is cooled to room temperature to obtain antiferroelectric modified high-energy-storage BiFeO3-BaTiO3 ceramic.

9. The method according to claim 7, wherein, The method includes the following steps: 1) Using Bi2O3, Fe2O3, BaCO3, TiO2, Ag2O, Ta2O5 and Nb2O5 as raw materials, the raw materials are thoroughly dried in a drying oven to remove moisture. The temperature of the drying oven is set to 80 to 100°C and the time is 12 hours. 2) Prepare the raw material powder obtained in step 1) according to the stoichiometric ratio; 3) Mix the raw material powder prepared in step 2), anhydrous ethanol and zirconium oxide grinding balls in a nylon ball mill jar, and then ball mill for 24 hours using a planetary ball mill to form a uniform mixture. The ball mill speed is 300 rpm. 4) Place the mixture obtained in step 3) into a forced-air drying oven for drying. The drying temperature is controlled at 80 to 100°C. Grind the obtained mixed dry powder evenly using a mortar and pestle. Place the evenly mixed powder into a crucible and compact it. Then place it into a muffle furnace for pre-firing. The pre-firing temperature is 800°C and the pre-firing time is 6 hours. After pre-firing, allow it to cool naturally to room temperature. 5) Add 0.1 wt% MnO2 to the pre-calcined powder obtained in step 4), and then perform a second ball milling with anhydrous ethanol as the medium. The ball mill speed is 300 rpm and the ball milling time is 24 hours. 6) After the second ball milling is completed, put the pre-fired powder obtained in step 5) into a drying oven to dry. The drying temperature is controlled at 80-100℃. Use a mortar and pestle to grind the dried pre-fired powder evenly. The pre-fired powder preparation is now complete. Next, prepare the casting slurry. 7) Mix the pre-calcined powder obtained in step 6) with polyvinyl butyral, ethanol, ethyl acetate, dibutyl phthalate, trioleic acid glyceride and polyethylene glycol, and ball mill for 12 hours at a speed of 100 rpm to obtain a uniform slurry. 8) The slurry obtained in step 7) is coated onto the substrate by tape casting, and after drying, the ceramic blank is peeled off from the substrate; 9) Press the ceramic blank obtained in step 8) using a warm isostatic press at 60℃ and 60 MPa to obtain a dense ceramic blank; 10) Sinter the dense ceramic blank obtained in step 9) at 600°C for 4 hours to remove organic matter; 11) The blank discs obtained in step 10) are sintered into ceramics through the following process: the temperature is raised to 950℃~1000℃ at a rate of 5℃ / min, held for 1 min, then rapidly cooled to 900℃ at a rate of 20℃ / min, held for 2 h, and finally cooled to room temperature to obtain antiferroelectric modified high-energy BiFeO3-BaTiO3 ceramics.

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