A barium titanate-based multilayer dielectric material with high energy storage density and a preparation method thereof

Abstract

The present invention relates to a barium titanate-based multilayer dielectric material with high energy storage density, which comprises a barium titanate-based dielectric ceramic having a chemical formula of (La x Ba y Sr z K u Na v Ca w Bi k )TiO3, wherein x=0-0.05, y=0.05-0.30, z=0-0.3, u=0.05-0.3, v=0.05-0.3, w=0.05-0.3 and k=0.1-0.3. The multilayer dielectric material has high energy storage density and energy storage efficiency, and excellent temperature and frequency stability. The present invention also provides a preparation method of the barium titanate-based multilayer dielectric material with high energy storage density, and a barium titanate-based multilayer dielectric element with high energy storage density.

Description

Technical Field

[0001] This invention relates to a high energy density barium titanate-based multilayer dielectric material and its preparation method. The dielectric material can be used as a dielectric energy storage capacitor, belonging to the field of functional ceramics technology. Background Technology

[0002] Dielectric capacitors, as the core energy storage devices of high-power pulse power supplies, have advantages such as high power density, ultra-fast charging and discharging capabilities, excellent thermal stability, and strong anti-aging properties. They play a vital role in the development of military equipment and the realization of scientific research and technology, such as cardiac pacemakers, camera flashes, nuclear effect simulation, metal forming, and hybrid electric vehicles.

[0003] With the miniaturization and weight reduction of pulsed power devices, the development of high-energy-density dielectric materials is becoming increasingly urgent. In the research field of high-energy-density materials, dielectric materials suitable for energy storage fall into four main categories: linear dielectrics (LD), ferroelectrics (FE), relaxor ferroelectrics (RFE), and antiferroelectrics (AFE). Barium titanate (BaTiO3)-based ceramics, due to their excellent electrical properties, including high dielectric constant and excellent ferroelectricity, are one of the superior candidate materials for preparing ceramic dielectric capacitors. However, traditional barium titanate-based ceramics have low breakdown strength, with a maximum breakdown field strength of only 50–80 kV / cm; and low energy storage density, approximately 0.3 J / cm³. 3 It is difficult to meet the needs of modern industry, and it is necessary to improve its performance.

[0004] Doping modification is the most effective way to improve the properties of BaTiO3-based dielectric ceramics. Researchers have added Bi(Li) to BaTiO3. 0.5 Nb 0.5 )O3 and Bi(Mg 0.5 Ti 0.5) The O3 composite perovskite system, specifically the 0.88BT-0.12(1-x)BLN-0.12xBMT-based dielectric ceramic, exhibits a breakdown strength of 290 kV / cm and a storage density of 2.4 J / cm². 3 (Chem.Eng.J.,2021,414:128760); In addition, some researchers have also used Ce element doping of 0.65BaTiO3-0.35Sr 0.2 Bi 0.2 TiO3 ceramics were used to obtain dielectric ceramics with excellent electrical properties, with a breakdown strength of up to 330 kV / cm and a storage energy density of approximately 2.57 J / cm². 3The energy storage efficiency is 81.30% (Ceram.Int,2021,47(22):32015-32024). These works all show that BaTiO3-based ceramics have great application potential in the field of dielectric energy storage. However, their breakdown field strength does not meet the application requirements and their energy storage efficiency is low, which seriously limits their application in high-power pulse power supplies. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a high-energy-density barium titanate-based multilayer dielectric material and its preparation method. By employing a high-entropy design of the BaTiO3-based dielectric ceramic components, its breakdown field strength is improved, thereby enhancing its energy storage performance. This provides a high-performance material to meet the development needs of high-power dielectric energy storage devices such as pulse power supplies.

[0006] In a first aspect, the present invention provides a high energy density barium titanate-based multilayer dielectric material, wherein the barium titanate-based dielectric ceramic contains a chemical formula of (La... x Ba y Sr z K u Na v Ca w Bi k TiO3, where x = 0 to 0.05, y = 0.05 to 0.30, z = 0 to 0.3, u = 0.05 to 0.3, v = 0.05 to 0.3, w = 0.05 to 0.3 and k = 0.1 to 0.3.

[0007] In this invention, high-entropy ceramics are constructed by doping with elements such as lanthanum, strontium, potassium, sodium, calcium and bismuth, which significantly improves the breakdown field strength and energy storage density of BaTiO3-based dielectric ceramics.

[0008] Preferably, the breakdown electric field of the high energy density barium titanate-based multilayer dielectric material is 420–910 kV / cm.

[0009] Preferably, the high energy density barium titanate-based multilayer dielectric material has an energy density of 4.4–6.8 J / cm³. 3 .

[0010] Preferably, the energy storage efficiency of the high energy density barium titanate-based multilayer dielectric material is 62.7–96.0%.

[0011] Secondly, the present invention provides a method for preparing the high energy density barium titanate-based multilayer dielectric material, comprising the following steps:

[0012] (1) Using barium titanate (BaTiO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), strontium carbonate (SrCO3), calcium carbonate (CaCO3), titanium dioxide (TiO2), bismuth oxide (Bi2O3), and lanthanum oxide (La2O3) as raw materials, according to the chemical formula (La x Ba y Sr z K u Na v Ca w Bi k TiO3, wherein x = 0~0.05, y = 0.05~0.30, z = 0~0.3, u = 0.05~0.3, v = 0.05~0.3, w = 0.05~0.3 and k = 0.1~0.3, is weighed and mixed, and then calcined and finely ground to obtain ceramic powder A;

[0013] (2) The obtained ceramic powder A is mixed evenly with solvent, dispersant, binder, homogenizer and plasticizer and then cast to obtain cast green film B.

[0014] (3) The obtained cast green film B is sliced, and electrodes are printed on the cast green film B by screen printing to obtain a green film with electrodes. The green film with electrodes is hot-pressed and stacked by hot pressing technology to obtain ceramic green film C.

[0015] (4) The multilayer ceramic green body C is subjected to plasticizing and sintering to obtain barium titanate-based multilayer dielectric ceramic D.

[0016] (5) Polish the barium titanate-based multilayer ceramic D and coat the end electrodes to obtain the barium titanate-based multilayer dielectric material E.

[0017] Preferably, in step (1), the purity of the raw materials is greater than 99%; the mixing method is ball milling; anhydrous ethanol or water is used as the ball milling medium, the rotation speed is 220-300 rpm, the time is 6-12 hours, and the grinding balls used are zirconia balls; the calcination temperature is 1100-1400℃, and the time is 2-4 hours.

[0018] Preferably, in step (2), the casting slurry formulation is as follows: powder 100wt%, PVB binder 4-10wt%, solvent 40-60wt%, dispersant 0.8-1.5wt%, plasticizer 4-6wt%, and homogenizer 0.5-1.0wt%. The molecular weight of PVB is 70,000-270,000; the solvent is a mixture of p-xylene (30%) and anhydrous ethanol (70%), or a mixture of butanone (40%) and anhydrous ethanol (60%), or a mixture of butanone (88.6%) and water (11.4%), or a mixture of anhydrous ethanol (68%) and toluene (32%), or a mixture of anhydrous ethanol (27%) and trichloroethylene (63%), or a mixture of n-acetone (88%) and butanone (12%), or a mixture of acetone (88%) and methane. The solvent is a mixture of benzene (12%) or a mixture of p-xylene (17%) and n-acetone (83%), all percentages being volume fractions; the dispersant is soybean oil, peanut oil, or fish oil; the plasticizer is a mixture of dibutyl phthalate (DBP) and polyethylene glycol (PEG-400), or a mixture of butyl benzyl phthalate (BBP) and polyethylene glycol (PEG-400), with the mass ratio of DBP to PEG-400 and the mass ratio of BBP to PEG-400 both being 1:1; the homogenizer is cyclohexanone.

[0019] Preferably, in step (3), the thickness of the cast film is 1 to 50 micrometers; the electrode in the screen printing is an Ag-Pd electrode, a Ni electrode, or a Pt electrode; the hot pressing temperature in the stack is 60 to 80°C, and the holding time is 1 to 5 minutes.

[0020] Preferably, in step (4), the temperature for descaling is 400-600℃ and the time is 1-2 hours;

[0021] Preferably, in step (4), the sintering process is to raise the temperature to 1000-1050°C at room temperature at a heating rate of 3-4°C / min, and then raise the temperature to 1200-1400°C at a heating rate of 2-4°C / min, and hold for 1-3 hours.

[0022] Preferably, in step (5), the terminal electrode is a nickel electrode, a copper electrode, or a silver electrode.

[0023] Thirdly, the present invention provides a barium titanate-based multilayer dielectric element with high energy storage density, comprising the aforementioned barium titanate-based dielectric ceramic with high energy storage density, and electrodes distributed on the surface of the barium titanate-based dielectric ceramic with high energy storage properties.

[0024] Beneficial effects:

[0025] Compared with existing technologies, this invention, through high-entropy design, such as doping with elements like lanthanum, strontium, potassium, sodium, calcium, and bismuth, achieves a strong breakdown field (maximum breakdown field strength up to 800 kV / cm) and high energy density (maximum energy density up to 6.62 J / cm²). 3 ) and high energy storage efficiency (maximum energy storage efficiency up to 95.92%) (La x Ba y Sr z K u Na v Ca w Bi k TiO3-based multilayer dielectric energy storage materials. The resulting materials have advantages such as high voltage resistance, lead-free and environmentally friendly properties, high energy density and energy storage efficiency, making them suitable for high-power pulse power supply applications and possessing significant application value. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 For (La) x Ba y Sr z K u Na v Ca w Bi k XRD patterns of TiO3-based dielectric energy storage materials; all samples are pure perovskite structures.

[0028] Figure 2 For (La) 0.05 Ba 0.18 Sr 0.18 K 0.115 Na 0.115 Ca 0.18 Bi 0.18 SEM image of TiO3-based multilayer dielectric energy storage material.

[0029] Figure 3 for (Ba 0.25 K 0.25 Ca 0.25 Bi 0.25 SEM image of TiO3-based multilayer dielectric energy storage material.

[0030] Figure 4 For (La) x Ba y Srz K u Na v Ca w Bi k The unipolar PE curves of the properties of TiO3-based dielectric energy storage materials.

[0031] Figure 5 For (La) x Ba y Sr z K u Na v Ca w Bi k Diothermal spectrum of TiO3-based dielectric energy storage materials. Detailed Implementation

[0032] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be described in detail below with reference to specific embodiments. It should be understood that the embodiments described in this specification are merely illustrative and not intended to limit the scope of the invention.

[0033] In this invention, the molecular formula of the high energy density barium titanate-based multilayer ceramic material is (La x Ba y Sr z K u Na v Ca w Bi k The material is TiO3, wherein x = 0–0.05, y = 0.05–0.30, z = 0–0.3, u = 0.05–0.3, v = 0.05–0.3, w = 0.05–0.3, and k = 0.1–0.3. This invention's material exhibits excellent breakdown electric field strength and energy storage characteristics, with a breakdown electric field reaching 800 kV / cm and an energy storage density of 6.62 J / cm³. 3 The energy storage efficiency is 95.92%. Specifically, the (La) of this invention... x Ba y Sr z K u Na v Ca w Bi k TiO3-based ceramics have a strong breakdown field, high energy density and energy storage efficiency, and are inexpensive, making them a low-cost, high-performance material for pulsed high-power power supply components.

[0034] Example 1: (La) x Ba y Sr z K u Na v Ca w Bi kTiO3, where x = 0.05, y = 0.18, z = 0.18, u = 0.115, v = 0.115, w = 0.18, k = 0.18.

[0035] The ceramic material of this embodiment was prepared by solid-state sintering, specifically according to the following steps:

[0036] (1) According to the molecular formula: (La x Ba y Sr z K u Na v Ca w Bi k The following raw materials are required for batching: barium titanate (BaTiO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), strontium carbonate (SrCO3), calcium carbonate (CaCO3), titanium dioxide (TiO2), bismuth oxide (Bi2O3), and lanthanum oxide (La2O3). These materials are to be weighed using an electronic balance with an accuracy of 0.001 g.

[0037] (2) The weighed raw materials were mixed and placed in a nylon can. Anhydrous ethanol was added to the can to a height not exceeding 1 / 3 of the can's height for mixing. Zirconia balls were used as the medium. The nylon can was placed on a horizontal ball mill and mixed for 8 hours. The zirconia balls had particle sizes of 3mm, 5mm, and 8mm, with a mass ratio of 3:4:3. The ball-milled slurry was poured into a tray and placed in an oven to dry. The dried powder was crushed and placed in a crucible. The crucible was then placed in a muffle furnace for calcination at 1150℃ for 3 hours to obtain ceramic powder.

[0038] (3) The obtained ceramic powder is placed in a planetary ball mill and ball milled at a speed of 300 rpm for 12 hours to obtain finely ground ceramic powder.

[0039] (4) Prepare casting slurry according to the mass ratio of ceramic powder: PVB: solvent: dispersant: plasticizer: homogenizer of 100: 6.4: 60: 1.4: 6: 0.5, wherein the solvent is a mixture of methyl ethyl ketone (40% by volume) and anhydrous ethanol (60% by volume), the dispersant is fish oil, the plasticizer is a mixture of dibutyl phthalate (DBP) and polyethylene glycol (PEG-400) in a mass ratio of 1:1, and the homogenizer is cyclohexanone.

[0040] (5) Pour the casting slurry into the casting machine, where the blade height is 140 micrometers and the speed is 0.7cm / s, to obtain the casting film.

[0041] (6) Cut the film strip and screen print platinum electrodes; stack the film strip with printed electrodes.

[0042] (7) Slice the stacked pieces and perform plastic removal treatment, wherein the plastic removal temperature is 600℃ and the heat preservation time is 1 hour.

[0043] (8) The plasticized blank is sintered in an atmospheric atmosphere at a temperature of 1210℃ for 3 hours. After naturally cooling to room temperature, the sample is taken out.

[0044] The prepared barium titanate-based ceramic material was polished to expose the inner electrode; then, silver, nickel, or copper end electrodes were coated on the exposed inner electrode to obtain a barium titanate-based multilayer dielectric energy storage material, and its structure and performance were tested.

[0045] Example 2: (La) x Ba y Sr z K u Na v Ca w Bi k TiO3, where x = 0.00, y = 0.20, z = 0.20, u = 0.10, v = 0.10, w = 0.20, k = 0.20. Except for the different values ​​of x, y, z, u, v, w, and k in step (1), the other steps are the same as in Example 1.

[0046] Example 3: (La) x Ba y Sr z K u Na v Ca w Bi k TiO3, where x = 0.00, y = 0.25, z = 0.00, u = 0.125, v = 0.125, w = 0.25, k = 0.25. Except for the different values ​​of x, y, z, u, v, w, and k in step (1), all other steps are the same as in Example 1.

[0047] Example 4 (Comparative): (La) x Ba y Sr z K u Na v Ca w Bi k TiO3, wherein x = 0.00, y = 0.25, z = 0.00, v = 0.00, u = 0.25, w = 0.25 and k = 0.25. Except for the different values ​​of x, y, z, u, v, w and k in step (1), the other steps are the same as in Example 1.

[0048] Table 1 shows a performance comparison between high-entropy barium titanate-based dielectric energy storage materials (Examples 1-3) and non-high-entropy barium titanate-based dielectric energy storage material (Example 4). From Examples 4 to 1, it can be seen that as the type of doping element increases, the entropy increases, and (La...) x Ba y Sr z K u Na v Ca w Bi k The breakdown field strength, energy density, and energy efficiency of TiO3-based dielectric energy storage materials also increase accordingly.

[0049] Table 1 (La x Ba y Sr z K u Na v Ca w Bi k Comparison of the performance of TiO3-based dielectric energy storage materials

[0050]

[0051]

[0052] Figure 1 XRD patterns of high-entropy barium titanate-based dielectric energy storage materials (Examples 1-3) and non-high-entropy barium titanate-based dielectric energy storage material (Example 4) are compared. All samples exhibit a pure perovskite structure, indicating that these elements can be well dissolved into the perovskite lattice. Furthermore, from Example 4 to Example 1, as the number of element types increases (entropy increases), the phase structure changes from tetragonal to cubic.

[0053] Figure 2 This is the SEM image of Example 1. Figure 3 The image shown is a SEM image of Example 4. The SEM image reveals that the ceramic sample exhibits well-developed, highly saturated, and dense grains with uniform distribution. Each layer is approximately 15 micrometers thick.

[0054] Figure 4 A comparison of the PE curves of high-entropy barium titanate-based dielectric energy storage materials (Examples 1-3) and non-high-entropy barium titanate-based dielectric energy storage material (Example 4) is shown. It can be seen that from Example 4 to Example 1, with the increase of elemental doping species (i.e., increase in entropy), the PE curve becomes thinner, and the breakdown field strength also increases accordingly. This is beneficial for obtaining high energy storage density and energy storage efficiency. Specifically, (La... 0.05 Ba 0.18 Sr 0.18 K 0.115 Na 0.115 Ca 0.18 Bi 0.18TiO3-based high-entropy dielectric ceramics have extremely fine PE curves.

[0055] Figure 5 A comparison of the dielectric temperature spectra of high-entropy barium titanate-based dielectric energy storage materials (Examples 1-3) and non-high-entropy barium titanate-based dielectric energy storage material (Example 4) is presented. It can be seen that as the number of element dopants increases (i.e., entropy increases), the dielectric peak shifts towards lower temperatures, and the dielectric loss decreases accordingly.

[0056] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this invention, and these modifications or substitutions should all be covered within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the scope defined in the claims.

Claims

1. A high energy density barium titanate-based multilayer dielectric material, characterized in that, The material contains barium titanate-based dielectric ceramics with the chemical formula (La). x Ba y Sr z K u Na v Ca w Bi k TiO3, where x = 0 to 0.05, y = 0.05 to 0.30, z = 0 to 0.3, u = 0.05 to 0.3, v = 0.05 to 0.3, w = 0.05 to 0.3 and k = 0.1 to 0.3, and x and z are not both 0.

2. The high energy storage density barium titanate-based multilayer dielectric material according to claim 1, characterized in that, The material has a breakdown electric field of 420–910 kV / cm and an energy storage density of 4.4–6.8 J / cm³. 3 The energy storage efficiency ranges from 62.7% to 96.0%.

3. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 1, characterized in that, Includes the following steps: (1) Barium titanate, sodium carbonate, potassium carbonate, strontium carbonate, calcium carbonate, titanium dioxide, bismuth oxide, and lanthanum oxide are selected as raw materials, according to the chemical formula (La x Ba y Sr z K u Na v Ca w Bi k TiO3, wherein x = 0~0.05, y = 0.05~0.30, z = 0~0.3, u = 0.05~0.3, v = 0.05~0.3, w = 0.05~0.3 and k = 0.1~0.3, is weighed and mixed, and then calcined and finely ground to obtain ceramic powder A; (2) The obtained ceramic powder A is mixed evenly with solvent, dispersant, binder, homogenizer and plasticizer and then cast to obtain cast green film B; (3) The obtained cast green film B is sliced, and electrodes are printed on the cast green film B by screen printing to obtain a green film with electrodes. The green film with electrodes is hot-pressed and stacked by hot pressing technology to obtain ceramic green film C. (4) The multilayer ceramic green body C is subjected to plasticizing and sintering to obtain barium titanate-based multilayer dielectric ceramic D; (5) Polish the barium titanate-based multilayer ceramic D and coat the end electrodes to obtain the barium titanate-based multilayer dielectric material E.

4. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 3, characterized in that, In step (1), the purity of the raw materials is greater than 99%; the mixing method is ball milling; anhydrous ethanol or water is used as the ball milling medium, the rotation speed is 220-300 rpm, the time is 6-12 hours, and the grinding balls used are zirconia balls; the calcination temperature is 1100-1400℃, and the time is 2-4 hours.

5. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 3, characterized in that, In step (2), the casting slurry is prepared as follows: ceramic powder A is 100 wt%, binder PVB is 4-10 wt%, solvent is 40-60 wt%, dispersant is 0.8-1.5 wt%, plasticizer is 4-6 wt%, and homogenizer is 0.5-1.0 wt%.

6. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 5, characterized in that, The molecular weight of PVB is 70,000 to 270,000; the dispersant is soybean oil, peanut oil or fish oil; the plasticizer is a mixture of dibutyl phthalate and polyethylene glycol, or a mixture of butyl benzyl phthalate and polyethylene glycol; the homogenizer is cyclohexanone.

7. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 3, characterized in that, In step (3), the thickness of the cast film is 1 to 50 micrometers; the electrode in the screen printing is an Ag-Pd electrode, a Ni electrode, or a Pt electrode; the hot pressing temperature in the stack is 60 to 80°C, and the holding time is 1 to 5 minutes.

8. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 3, characterized in that, In step (4), the temperature for descaling is 400–600℃, and the time is 1–2 hours; The sintering process involves heating the temperature to 1000–1050°C at room temperature at a rate of 3–4°C / min, followed by heating to 1200–1400°C at a rate of 2–4°C / min, and holding at that temperature for 1–3 hours.

9. The method for preparing the high energy density barium titanate-based multilayer dielectric material according to claim 3, characterized in that, In step (5), the terminal electrode is a nickel electrode, a copper electrode, or a silver electrode.

10. A barium titanate-based multilayer dielectric device with high energy storage density, characterized in that, It includes the high energy storage density barium titanate-based dielectric ceramic as described in claim 1, and electrodes distributed on the surface of the high energy storage barium titanate-based dielectric ceramic.

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