A Tungsten Bronze-Supported Energy Storage Ceramic Material and Its Preparation Method

Abstract

This invention provides a tungsten bronze-structured energy storage ceramic material and its preparation method, belonging to the field of functional ceramics technology. The general formula of the tungsten bronze-structured energy storage ceramic material is: A x Sr 5‑x BiTi3Nb 7‑y‑z Sb y Ta z O 30 Where A is a divalent element, 0≤x≤2, 0≤y≤1, 0≤z≤1; and x, y, and z are not all zero. Based on the specific composition of the filled tungsten bronze-based energy storage ceramic, a high-entropy strategy was introduced to design A… x Sr 5‑x BiTi3Nb 7‑y‑ z Sb y Ta z O 30 The series of energy storage ceramic materials breaks long-range ordered polarization, improves breakdown characteristics, and increases energy storage density and efficiency to achieve excellent capacitor energy storage.

Description

Technical Field

[0001] This invention belongs to the field of functional ceramics technology, and specifically relates to a full-fill tungsten bronze structure energy storage ceramic material and its preparation method. Background Technology

[0002] Compared to batteries and solid oxide fuel cells, dielectric ceramic capacitors have gradually become a hot research topic in the energy storage field due to their distinctive characteristics such as ultra-high power density, ultra-fast charge and discharge rates, and excellent storage stability. Tungsten bronze structure is the second largest class of lead-free dielectric material structures after perovskite structure. Tetragonal tungsten bronze (TTB) compounds, as typical ferroelectric materials, have attracted widespread attention due to their complex structure and rich properties. The general structural formula of tetragonal tungsten bronze is (A1)2(A2)4(C)4(B1)2(B2)8O. 30 Its unit cell is composed of a lattice network formed by 10 oxygen octahedral BO6 atoms connected at common vertices, thus forming three different sizes of voids: A1, A2, and C (A1 is a square void with a coordination number of 12; A2 is a pentagonal void with a coordination number of 15; C is a triangular void). Based on the degree of ion filling, it can be divided into three types: filled (all three voids are filled), filled (A1 and A2 are filled, C is empty), and unfilled (A1 and A2 are partially filled, C is empty). Tungsten bronze has a more complex structure than perovskite oxides (ABO3), and the non-equivalent A, B, and C site voids in its crystal structure can be occupied by ions with different ionic radii and valence states, giving tungsten bronze a high degree of flexibility in compositional design and freedom in structural control.

[0003] However, tungsten bronze-based energy storage ceramics, especially filled-in tungsten bronze-based ceramics, face the challenge of balancing high effective energy storage density and high energy storage efficiency, hindering their application in advanced capacitors. The effective energy storage density of filled-in tungsten bronze-based energy storage ceramics has not yet reached 5 J / cm³. 3 Not to mention maintaining ultra-high energy storage efficiency while possessing high effective energy storage density. According to previous research, the main reasons for the poor energy storage performance of tungsten bronze are the low breakdown field strength caused by abnormally grown rod-shaped grains and the large polarization hysteresis that is difficult to suppress due to its complex internal structure. Developing high-performance tungsten bronze-based energy storage ceramics is of great significance for enriching the composition of dielectric materials and expanding their application range in capacitors. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a filled-in tungsten bronze structure energy storage ceramic material and its preparation method. Based on the specific composition of the filled-in tungsten bronze-based energy storage ceramic, a high-entropy strategy is introduced to design A... x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 The series of energy storage ceramic materials breaks long-range ordered polarization, improves breakdown characteristics, and increases energy storage density and efficiency to achieve excellent capacitor energy storage.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On one hand, the present invention provides a tungsten bronze-structured energy storage ceramic material, wherein the general formula of the tungsten bronze-structured energy storage ceramic material is: A x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 A is a divalent element, 0≤x≤2, 0≤y≤1, 0≤z≤1; x, y and z are not all 0.

[0007] Furthermore, A consists of at least two divalent elements, 1 ≤ x ≤ 2, 0 <y≤1,0<z≤1。

[0008] Furthermore, A is one or more of Ba, Ca, and Mg.

[0009] On the other hand, the present invention provides a method for preparing energy storage ceramic materials, comprising: S1 weighing A according to stoichiometric ratios. x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 S2. The oxide or carbonate powder corresponding to the element is mixed and pre-fired and ground to obtain ceramic powder; S3. The obtained ceramic powder is mixed with sintering aid, then a binder is added and mixed, and then granulated, sieved and shaped to obtain ceramic green body; S4. The ceramic green body is debinded and sintered to obtain the final product.

[0010] Furthermore, the average particle size of the ceramic powder obtained after grinding is 1.0-50.0 μm.

[0011] Furthermore, the pre-firing temperature is 1000-1100℃, and the temperature is maintained for 2.0-10.0 hours.

[0012] Furthermore, in step S1, the mixture is ball-milled in a protective medium at a speed of 300-400 r / min for 8-16 hours.

[0013] Furthermore, the amount of the sintering aid added is 0.8-1.2 mol% of the total molar amount of the ceramic powder.

[0014] Furthermore, the ceramic powder and the sintering aid are mixed by ball milling, wherein the ball milling process is as follows: ball milling at a speed of 500-800 r / min for 18-30 h.

[0015] Furthermore, in step S3, the temperature for removing the adhesive is 550-650℃, and the adhesive removal time is 2.0-4.0h. Subsequently, sintering is carried out at a temperature of 1200-1300℃ for a time of 2.0-4.0h.

[0016] The beneficial effects of the technical solutions provided by the embodiments of the present invention include:

[0017] This invention utilizes Sr5BiTi3Nb7O 30 Using a filled-in tetragonal tungsten bronze-based energy storage ceramic as the target, the A-site, B-site, and both A-site and B-site are replaced to achieve an entropy value of not less than 1.8R, realizing a high-entropy effect, breaking long-range ordered polarization, and obtaining a highly disordered dipole glass polarization configuration. This allows for a grain size of no more than 2μm, improving breakdown characteristics, increasing energy storage density and efficiency, and achieving excellent capacitive energy storage. The technical solution proposed in this invention can achieve a maximum energy storage capacity of 8.9 J / cm² under a high electric field of 86 kV / mm. 3 With a high energy storage density and 91% energy storage efficiency, it can achieve at least 5 J / cm² under a high electric field of 60 kV / mm. 3 The energy storage density and energy storage efficiency are high, and the prepared energy storage ceramic material exhibits temperature and frequency stability, without undergoing a phase transition within a wide temperature range of -150 to 200℃. rec The attenuation of η does not exceed 10%, and within the range of 10Hz to 100Hz, W rec The variation of η with frequency is also very small, with attenuation not exceeding 10%. Attached Figure Description

[0018] 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.

[0019] Figure 1 X-ray diffraction patterns provided for embodiments and comparative examples of the present invention;

[0020] Figure 2 SEM images and corresponding average grain sizes are provided for the embodiments and comparative examples of the present invention. a is Example 1, b is Example 4, and c is Comparative Example 1.

[0021] Figure 3 The dielectric temperature spectra provided for the embodiments and comparative examples of the present invention are shown in Figure a for Example 1, Figure b for Example 4, and Figure c for Comparative Example 1.

[0022] Figure 4 The unipolar hysteresis loop diagrams provided for embodiments and comparative examples of the present invention;

[0023] Figure 5 The ceramic material provided in Embodiment 1 of the present invention, at 60 kV / mm, has a temperature and W rec The relationship between the value of η and the value of η;

[0024] Figure 6 The ceramic material provided in Embodiment 1 of the present invention, at 60kV / mm, has a frequency and W rec The relationship between the value of η and the value of η. Detailed Implementation

[0025] The present invention will be further described in detail below through specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product instructions. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be obtained commercially.

[0026] As used herein, the terms “comprising,” “including,” “having,” or any other variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus that includes listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Unless the context clearly specifies otherwise, the singular forms “an” and “the” include a plural of objects under discussion.

[0027] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, this invention can be implemented using any prior art methods, apparatus, and materials similar to or equivalent to those described in the embodiments of this invention, based on the knowledge of those skilled in the art and the description of this invention.

[0028] Unless otherwise specified, in this embodiment of the invention, all processes are carried out at room temperature, and the measurement is performed using mass percentage or mass percentage content.

[0029] This invention provides a tungsten bronze-structured energy storage ceramic material, the general formula of which is:

[0030] A x Sr5-x BiTi3Nb 7-y-z Sb y Ta z O 30 , where A is a divalent element, 0 ≤ x ≤ 2, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1; x, y, and z are not all 0.

[0031] In this invention, by taking the filled tetragonal tungsten bronze-based energy storage ceramics as the implementation target, replacing the A-site, B-site, and both the A-site and B-site, with an entropy value not less than 1.8R to achieve the high-entropy effect, breaking the long-range ordered polarization, obtaining a highly disordered dipole glass polarization configuration, the grain size can be made no larger than 2 μm, improving the breakdown characteristics, increasing the energy storage density and energy storage efficiency, and achieving excellent capacitive energy storage. The technical solution proposed in this invention can achieve a maximum energy storage density of 8.9 J / cm 30 under a high electric field of 86 kV / mm and an energy storage efficiency of 91%, and a minimum energy storage density of at least 5 J / cm 3 under a high electric field of 60 kV / mm and an energy storage efficiency of over 90%. At the same time, the prepared energy storage ceramic material has temperature and frequency stability, does not undergo a phase change in a wide temperature range of -15~200 °C, and the attenuation of W 3 and η does not exceed 10%. In the range of 10 Hz to 100 Hz, the changes of W rec and η with frequency are also very small, with an attenuation not exceeding 10%. rec The dipole glass polarization configuration means that the polarization magnitudes and angles between adjacent dipoles are completely different, and the polarization scale is close to the atomic level.

[0032] Preferably, A is at least two divalent elements, 1 ≤ x ≤ 2, 0 < y ≤ 1, 0 < z ≤ 1. By replacing A and the B-site, with an entropy value not less than 2R, the grain size can be made less than 1 μm, obtaining a highly disordered dipole glass polarization configuration and a wide distribution range of polarization angles, covering all directions and generating nano-domains or PNRs of a few nanometers.

[0033]

[0034] A is one or more of Ba, Ca, and Mg.

[0035] This invention embodiment also provides a preparation method for the above-mentioned filled tungsten bronze structure energy storage ceramic material, including:

[0036]

[0036] S1 Weigh A, x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements, pre-firing and grinding them.

[0037] Specifically, this invention uses commercially available high-purity oxide or carbonate powders. For illustrative purposes, in the embodiments of this invention, the raw materials used include barium carbonate with a purity of 99.95%, bismuth oxide with a purity of 99.9%, strontium carbonate with a purity of 99.95%, titanium dioxide with a purity of 99.8%, niobium oxide with a purity of 99.9%, calcium carbonate with a purity of 99.99%, antimony trioxide with a purity of 99.95%, and tantalum pentoxide with a purity of 99.95%.

[0038] The above-mentioned oxide or carbonate powders are mixed by ball milling. Specifically, the mixture is ball-milled in a protective medium at a speed of 300-400 r / min for 8-16 hours, such as at a speed of 300 r / min, 350 r / min, or 400 r / min. The ball milling time can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or 16 hours, preferably 12 hours. Specifically, the protective medium is a volatile organic solvent, such as ethanol.

[0039] Pre-calcination primarily transforms the mixed powder into an oxidized state, converting raw materials into cooked materials. For example, carbonates decompose into oxides and carbon dioxide, or organic matter in the mixed powder is removed through pre-calcination. The pre-calcination temperature is determined based on the decomposition temperature of the oxide or titanate powder used. In this embodiment of the invention, the pre-calcination temperature is 1000-1100℃, with a holding time of 2.0-10.0 h. Preferably, the holding time is 4 h, and the heating rate is no greater than 10℃ / min, preferably 5℃ / min.

[0040] After pre-firing, grinding is performed, and the average particle size of the ceramic powder obtained after grinding is 1.0-50.0 μm. This invention improves sintering quality while reducing sintering temperature by limiting the average particle size of the ceramic powder in conjunction with subsequent sintering aids, thus avoiding grain growth. The size of the grains affects the breakdown strength of energy storage ceramics. Specifically, the smaller the average particle size, the easier it is to over-fire during sintering, leading to grain growth and reduced activity. On the other hand, a larger average grain size makes element diffusion difficult, making it hard to form perfect crystals and affecting the performance of the final product. Finally, this average particle size is beneficial for compatibility with sintering aids, thereby improving quality.

[0041] S2 mixes the obtained ceramic powder with a sintering aid, then adds a binder and mixes again, followed by granulation, sieving and molding to obtain a ceramic green body.

[0042] The amount of the sintering aid added is 0.8-1.2 mol% of the total molar percentage of the ceramic powder, for example, 0.8 mol%, 0.9 mol%, 1.0 mol%, 1.1 mol%, or 1.2 mol%. The mixture is then mixed using a ball milling process at 500-800 r / min for 18-30 hours, with milling speeds of 500 r / min, 600 r / min, 700 r / min, or 800 r / min. The milling time can be 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, or 30 hours. The sintering aid is manganese dioxide or copper oxide. Preferably, the average particle size of the sintering aid is 0.5-10.0 μm. Within the above particle size range and combined with the mixing process, the sintering aid coats the surface of the ceramic powder and deforms under impact, which helps to improve the subsequent sintering quality, that is, to form grains of less than 2 μm and increase the breakdown strength Eb of the ceramic powder material.

[0043] The binder is a 5 wt.% aqueous solution of polyvinyl alcohol, and the amount of binder added is 5-6 wt.% of the ceramic powder mass. The sieve used for sieving is 40 mesh. The mold used for tableting has a diameter of 8-10 mm.

[0044] S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

[0045] The binder removal temperature is 550-650℃, which can be 550℃, 600℃, or 650℃, and the binder removal time is 2.0-4.0 hours, which can be 2 hours, 3 hours, or 4 hours. Sintering is then performed at 1200-1300℃ for 2.0-4.0 hours. The binder removal heating rate does not exceed 8℃ / min, and the sintering heating rate does not exceed 10℃ / min. Preferably, the powder embedding method is used for sintering.

[0046] To better illustrate the embodiments of the present invention, the present invention will be further described in detail below through specific examples.

[0047] Example 1

[0048] This embodiment provides a filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material and its preparation method, including the following steps:

[0049] S1 is weighed according to the stoichiometric ratio: BaCaSr3BiTi3Nb5SbTaO 30 Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements, pre-firing, and grinding. The pre-firing temperature is 1000℃, the pre-firing time is 2h, and the average particle size after grinding is 20μm.

[0050] S2: The obtained ceramic powder is mixed with a sintering aid, then a binder is added and mixed again. The mixture is then granulated, sieved, and shaped to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill jar for ball milling at 500 r / min for 24 h. The sintering aid is manganese dioxide with a purity of 99.95%, added at 1 mol% of the total powder volume. The mixture is then poured into a glass petri dish and dried in an oven. The dried powder and binder are ground and mixed in a mortar, then granulated. The mixture is then pressed into sheets using a 10 mm diameter die to obtain a ceramic green body. The binder is a polyvinyl alcohol aqueous solution, added at 6 wt% of the ceramic powder mass.

[0051] S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

[0052] The ceramic green body was placed in a crucible and covered with a layer of ceramic powder for debinding. The debinding temperature was 550℃ and the debinding time was 2 hours. After debinding, sintering was performed at 1240℃ for 3 hours to obtain the infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, denoted as SBTN-AB1.

[0053] Example 2

[0054] This embodiment provides a filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material and its preparation method, including the following steps:

[0055] S1 is weighed according to the stoichiometric ratio: BaCaSr3BiTi3Nb5SbTaO 30 Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements, pre-firing, and grinding. The pre-firing temperature is 1050℃, the pre-firing time is 5 hours, and the average particle size after grinding is 1 μm.

[0056] S2. The obtained ceramic powder is mixed with a sintering aid, then a binder is added and mixed again. The mixture is then granulated, sieved, and shaped to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill jar for ball milling at 600 r / min for 18 h. The sintering aid is copper oxide with a purity of 99.95%, added at 0.8 mol% of the total powder volume. The mixture is then poured into a glass petri dish and dried in an oven. The dried powder and binder are ground and mixed in a mortar, then granulated. The mixture is then pressed into sheets using a 10 mm diameter die to obtain a ceramic green body. The binder is a polyvinyl alcohol aqueous solution, added at 5 wt% of the ceramic powder mass.

[0057] S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

[0058] The ceramic green body was placed in a crucible and covered with a layer of ceramic powder for debinding. The debinding temperature was 600℃ and the debinding time was 3 hours. After debinding, sintering was performed at 1200℃ for 2 hours to obtain the infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, denoted as SBTN-AB2.

[0059] Example 3

[0060] This embodiment provides a filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material and its preparation method, including the following steps:

[0061] S1 is weighed according to the stoichiometric ratio: BaCaSr3BiTi3Nb5SbTaO 30 Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements, pre-firing and grinding them. The pre-firing temperature is 1100℃, the pre-firing time is 10h, and the average particle size after grinding is 50μm.

[0062] S2: The obtained ceramic powder is mixed with a sintering aid, then a binder is added and mixed again. The mixture is then granulated, sieved, and shaped to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill jar for ball milling at 800 r / min for 30 h. The sintering aid is copper oxide with a purity of 99.95%, added at 1.2 mol% of the total powder volume. The mixture is then poured into a glass petri dish and dried in an oven. The dried powder and binder are ground and mixed in a mortar, then granulated. The mixture is then pressed into sheets using a 10 mm diameter die to obtain a ceramic green body. The binder is a polyvinyl alcohol aqueous solution, added at 6 wt% of the ceramic powder mass.

[0063] S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

[0064] The ceramic green body was placed in a crucible and covered with a layer of ceramic powder for debinding. The debinding temperature was 650℃ and the debinding time was 4 hours. After debinding, sintering was performed at 1300℃ for 4 hours to obtain the infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, denoted as SBTN-AB3.

[0065] Example 4

[0066] This embodiment provides a filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material and its preparation method, including the following steps:

[0067] S1 weighs out BaCaSr3BiTi3Nb7O according to the stoichiometric ratio. 30Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements, pre-firing, and grinding. The pre-firing temperature is 1000℃, the pre-firing time is 2h, and the average particle size after grinding is 20μm.

[0068] S2: The obtained ceramic powder is mixed with a sintering aid, then a binder is added and mixed again. The mixture is then granulated, sieved, and shaped to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill jar for ball milling at 500 r / min for 24 h. The sintering aid is manganese dioxide with a purity of 99.95%, added at 1 mol% of the total powder volume. The mixture is then poured into a glass petri dish and dried in an oven. The dried powder and binder are ground and mixed in a mortar, then granulated. The mixture is then pressed into sheets using a 10 mm diameter die to obtain a ceramic green body. The binder is a polyvinyl alcohol aqueous solution, added at 6 wt% of the ceramic powder mass.

[0069] S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

[0070] The ceramic green body was placed in a crucible and covered with a layer of ceramic powder for debinding. The debinding temperature was 550℃ and the debinding time was 2 hours. After debinding, sintering was performed at 1220℃ for 3 hours to obtain the infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, denoted as SBTN-A.

[0071] Example 5

[0072] Unlike Example 4, the filled-in tungsten bronze-based high-entropy ferroelectric energy storage ceramic material in this example is Sr5BiTi3Nb5SbTaO. 30 The prepared infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated SBTN-B.

[0073] Comparative Example 1

[0074] Unlike Example 1, the filled-in tungsten bronze-based high-entropy ferroelectric energy storage ceramic material in this comparative example is Sr5BiTi3Nb7O. 30 The prepared infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated as SBTN.

[0075] Comparative Example 2

[0076] Unlike Example 1, in step S1 of this comparative example, the average particle size of the ceramic powder obtained after grinding is 55 μm. The prepared filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated as SBTN-AB4.

[0077] Comparative Example 3

[0078] Unlike Example 1, in step S2 of this comparative example, the amount of the sintering aid added is 1.5 mol% of the total molar number of the ceramic powder. The prepared full-fill tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated as SBTN-AB5.

[0079] Comparative Example 4

[0080] Unlike Example 1, in step S2 of this comparative example, the amount of the sintering aid added is 0.5 mol% of the total molar number of the ceramic powder. The prepared infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated as SBTN-AB6.

[0081] Comparative Example 5

[0082] Unlike Example 1, in step S2 of this comparative example, the ball milling process is as follows: ball milling at 400 r / min for 30 h. The prepared infilled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material is designated as SBTN-AB7.

[0083] Performance Characterization

[0084] Since Examples 1, 2, and 3 are similar, and Examples 4 and 5 are similar, and Comparative Examples 1, 2-5 have slight performance differences from Example 1, but the differences in the accompanying drawings are minor, Examples 1, 4, and Comparative Example 1 are selected for illustration in conjunction with the accompanying drawings. Other examples and comparative examples are illustrated using test data. X-ray diffraction tests were performed on the filled-in tungsten bronze-based high-entropy ferroelectric energy storage ceramic materials prepared in Examples 1, 4, and 1, respectively. Figure 1 X-ray diffraction patterns for Example 1 (SBTN-AB1), Example 4 (SBTN-A), and Comparative Example 1 (SBTN) are shown. From Figure 1 As can be seen, the prepared ceramic material has virtually no obvious impurities.

[0085] After polishing the surface of the ceramic materials prepared in Examples 1, 4 and Comparative Example 1, the ceramics were placed in an unsealed crucible for hot corrosion treatment. The hot corrosion temperature was 1000-1150℃, the heating rate was 7℃ / min, and then scanning electron microscopy was performed. Figure 2 Here are scanning electron microscope (SEM) images of each embodiment and comparative example, from... Figure 2 As can be seen from this, with the increase of doped substitution ions, the entropy of the system increases, the grain size becomes smaller, and the average grain size (G) decreases. a The grain size was reduced from 3.42 μm in SBTN ceramics to 0.67 μm in SBTN-AB1 ceramics. This grain refinement helps to improve the breakdown field strength of the ceramics.

[0086] The ceramic electrodes prepared in Examples 1, 4 and Comparative Example 1 were ground, polished and silver-plated. The electrode sintering temperature was 550℃, the heating rate was 2℃ / min, and the holding time was 20 minutes. Then the electrical performance was tested.

[0087] The dielectric properties of the ceramics prepared and processed with electrode plating according to Examples 1, 4, and Comparative Example 1 were characterized. Figure 3 The dielectric temperature spectra of Example 1 (SBTN-AB1), Example 4 (SBTN-A), and Comparative Example 1 (SBTN) are shown. Figure 3 As can be seen, the increase in entropy enhances the relaxation behavior of the material. This is manifested in the fact that the phase transition of SBTN-AB1 is diffuse in the range of -100℃ to 200℃, and the enhanced relaxation helps to improve the energy storage performance.

[0088] Unipolar hysteresis loop tests were performed on the ceramics prepared and processed with electrodes in Examples 1, 4, and 1 (Comparative Example 1), respectively. Figure 4 The diagram shows the unipolar hysteresis loops for Example 1 (SBTN-AB1), Example 4 (SBTN-A), and Comparative Example 1 (SBTN). From... Figure 4 As can be seen, the introduction of multiple ions at the A and B sites increases the system's configurational entropy, resulting in a significant improvement in energy storage performance. The effective energy storage density is increased from 2.12 J / cm³ of SBTN. 3 The efficiency was increased to 8.9 J / cm² for SBTN-AB1. 3 The breakdown electric field increased from 30 kV / mm in SBTN to 86 kV / mm in SBTN-AB. Meanwhile, while increased effective energy density generally leads to increased energy loss and decreased energy storage efficiency, the energy storage efficiencies of SBTN-A and SBTN-AB1 remain above 90%, thanks to the reduced polarization hysteresis caused by the high entropy effect.

[0089] Figure 5 W for SBTN-AB1 ceramic at 60 kV / mm, as a function of temperature and frequency. rec The values ​​of W and η show that as the temperature increases from 25℃ to 140℃, W... rec With an η value attenuation not exceeding 10%, within the range of 10Hz to 100Hz, the W of SBTN-AB1 rec The variation of η with frequency is also very small, with attenuation not exceeding 10%.

[0090] The performance test data for each embodiment and comparative example are shown in Table 1.

[0091] Table 1 Performance test data for each embodiment and comparative example

[0092]

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tungsten bronze-structured energy storage ceramic material, characterized in that, The general formula for the filled tungsten bronze structure energy storage ceramic material is: A x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 Where A is at least two divalent elements, 1≤x≤2, 0 <y≤1,0<z≤1; The A is one or more of Ba, Ca, and Mg.

2. A method for preparing the energy storage ceramic material as described in claim 1, characterized in that, include: S1 weighs A according to the stoichiometric ratio. x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 Ceramic powder is obtained by mixing the oxide or carbonate powders corresponding to the elements and then pre-firing and grinding them. S2 mixes the obtained ceramic powder with a sintering aid, then adds a binder and mixes, followed by granulation, sieving and molding to obtain a ceramic green body; S3 involves removing the binder from the ceramic green body and sintering it to obtain the final product.

3. The preparation method according to claim 2, characterized in that, The average particle size of the ceramic powder obtained after grinding is 1.0-50.0 μm.

4. The preparation method according to claim 2, characterized in that, The preheating temperature is 1000-1100℃, and the temperature is maintained for 2.0-10.0 hours.

5. The preparation method according to claim 2, characterized in that, In step S1, the mixture is mixed using a ball milling process, and is ball milled in a protective medium at a speed of 300-400 r / min for 8-16 hours.

6. The preparation method according to claim 2, characterized in that, The amount of the sintering aid added is 1 mol of the total moles of the ceramic powder.

7. The preparation method according to claim 6, characterized in that, The ceramic powder and sintering aid are mixed by ball milling, which is performed at a speed of 500-800 r / min for 18-30 h.

8. The preparation method according to claim 2, characterized in that, The temperature for debinding in step S3 is 550-650℃, and the debinding time is 2.0-4.0h. Then, sintering is carried out at a temperature of 1200-1300℃ for 2.0-4.0h.

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