Full-filled tungsten bronze structure energy storage ceramic material and preparation method thereof

Abstract

The invention provides a full-filled tungsten bronze structure energy storage ceramic material and a preparation method, and belongs to the technical field of functional ceramics, the full-filled tungsten bronze structure energy storage ceramic material has a composition general formula of AxSr5-xBiTi3Nb7-y-zSbyTazO30, A is a divalent element, 0 < = x < = 2, 0 < = y < = 1, and 0 < = z < = 1; x, y and z are not all 0. A high-entropy strategy is introduced on the basis of specific components of full-filled tungsten bronze-based energy storage ceramic, an AxSr5-xBiTi3Nb7-y-zSbyTazO30 series energy storage ceramic material is designed, long-range ordered polarization is broken, the breakdown characteristic is improved, the energy storage density and the energy storage efficiency are improved, and excellent capacitive energy storage is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of functional ceramics, and particularly relates to a filled tungsten bronze structure energy storage ceramic material and a preparation method thereof. Background Art

[0002] Compared with batteries and solid oxide fuel cells, dielectric ceramic capacitors have gradually become a hot research topic in the field of energy storage due to their distinctive characteristics such as ultra-high power density, ultra-fast charge and discharge rate, and excellent storage stability. Tungsten bronze structure is the second largest type of lead-free dielectric material structure after perovskite structure. Tetragonal tungsten bronze (TTB) structure 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 octahedrons BO6 connected by 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 15 coordination; C is a triangular void). According to the degree of ion filling, it can be divided into three types: filled type (all three voids are filled), full type (A1 and A2 are fully filled, C is empty), and non-filled type (A1 and A2 are partially filled, C is empty). Tungsten bronze has a more complex structure than perovskite oxide (ABO3), and the unequal A, B and C voids in the crystal structure can be occupied by ions of different ionic radii and valence states, which makes the tungsten bronze structure have a large degree of flexibility in component design and freedom in structural regulation.

[0003] However, tungsten bronze-based energy storage ceramics, especially filled tungsten bronze-based ceramics, face the challenge of balancing high effective energy storage density and high energy storage efficiency, which hinders their application in advanced capacitors. The effective energy storage density of filled tungsten bronze-based energy storage ceramics has not yet reached 5J / cm 3 , not to mention the high effective energy storage density while maintaining ultra-high energy storage efficiency. According to previous research results, the main reason for the poor energy storage performance of tungsten bronze is the low breakdown field strength caused by abnormally grown rod-shaped grains and the large polarization hysteresis that is difficult to suppress due to the complex internal structure. The development of 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] In order to solve the above problems, the present invention provides a filled tungsten bronze structure energy storage ceramic material and a preparation method. Based on the specific components of filled tungsten bronze-based energy storage ceramics, a high entropy strategy is introduced to design A x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 A series of energy storage ceramic materials break the long-range ordered polarization, improve the breakdown characteristics, increase the energy storage density and energy storage efficiency, and achieve excellent capacitive energy storage.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

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

[0007] Furthermore, A is 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 an energy storage ceramic material, comprising: S1 weighing A and x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powder; S2: the obtained ceramic powder is mixed with a sintering aid, and then a binder is added and mixed, and then granulated, sieved and formed to obtain a ceramic green body; S3: the ceramic green body is debinded and sintered to obtain.

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

[0011] Furthermore, the pre-burning temperature is 1000-1100° C. and maintained for 2.0-10.0 hours.

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

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

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

[0015] Furthermore, in step S3, the debinding temperature is 550-650° C., the debinding time is 2.0-4.0 h, and then sintering is performed, the sintering temperature is 1200-1300° C., and the sintering time is 2.0-4.0 h.

[0016] The beneficial effects brought by the technical solution provided by the embodiment of the present invention include:

[0017] The present invention is to Sr5BiTi3Nb7O 30 The full-type tetragonal tungsten bronze-based energy storage ceramic is used as the implementation target. The A position, B position and A position and B position are replaced. The entropy value is not less than 1.8R, and the high entropy effect is achieved. The long-range ordered polarization is broken to obtain a highly disordered dipole glass polarization configuration. The grain size can be no more than 2μm, the breakdown characteristics are improved, the energy storage density and energy storage efficiency are increased, and excellent capacitance energy storage is obtained. The technical solution proposed in the present invention can achieve a maximum of 8.9J / cm under a high electric field of 86kV / mm. 3 The energy storage density and energy storage efficiency of 91% can achieve at least 5J / cm at a high electric field of 60kV / mm. 3 The energy storage density and energy storage efficiency of more than 90% are achieved. At the same time, the prepared energy storage ceramic material has temperature and frequency stability, and does not undergo phase change in a wide temperature range of -150 to 200 ° C. rec The attenuation of and η does not exceed 10% in the range of 10Hz to 100Hz, W rec The changes of and η with frequency are also very small, and the attenuation does not exceed 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

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

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

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

[0025] The present invention is further described in detail below by specific embodiments. However, it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0026] As used herein, the words "comprises," "including," "having," or any other variations thereof, are intended to cover a 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. The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0027] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, any methods, equipment, and materials of the prior art that are similar or equivalent to the methods, equipment, and materials in the embodiments of the present invention may be used to implement the present invention, based on the prior art mastery of those skilled in the art and the description of the present invention.

[0028] Without further explanation, in the embodiments of the present invention, each process is carried out at room temperature, and the measurement is in terms of mass percentage or mass content.

[0029] The present invention provides a filled tungsten bronze structure energy storage ceramic material, the composition formula of the filled tungsten bronze structure energy storage ceramic material 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] The present invention aims at the filled tetragonal tungsten bronze-based energy storage ceramics, replaces the A-site, B-site, and both the A-site and B-site, with the entropy value not less than 1.8R, realizes the high-entropy effect, breaks the long-range ordered polarization, obtains a highly disordered dipole glass polarization configuration, can achieve a grain size not greater than 2 μm, improves the breakdown characteristics, increases the energy storage density and energy storage efficiency, and obtains excellent capacitive energy storage. The technical solution proposed by the present invention can achieve a maximum energy storage density of 8.9 J / cm³ and an energy storage efficiency of 91% under a high electric field of 86 kV / mm 30 and a minimum energy storage density of at least 5 J / cm³ and an energy storage efficiency of more than 90% under a high electric field of 60 kV / mm. 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 -150 to 200 °C, and the decay of W 3 and η does not exceed 10%. In the range of 10 Hz to 100 Hz, the changes of W 3 and η with frequency are also very small, and the decay does not exceed 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. rec Preferably, A is at least two divalent elements, 1 ≤ x ≤ 2, 0 < y ≤ 1, 0 < z ≤ 1. By replacing the A-site and B-site, with the entropy value not less than 2R, a grain size less than 1 μm can be achieved, a highly disordered dipole glass polarization configuration can be obtained, and the distribution range of the polarization angle is very wide, covering all directions and generating nano-domains or PNRs of a few nanometers.

[0032] The A is one or more of Ba, Ca, and Mg.

[0033] The embodiment of the present invention also provides a preparation method of the above-mentioned filled tungsten bronze structure energy storage ceramic material, including:

[0034] S1 Weigh A,

[0035] Sr,

[0036] BiTi3Nb, x Sr, 5-x BiTi3Nb, 7-y-z Sb, y Ta, z O, 30The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powder.

[0037] Specifically, the present invention purchases commercially available high-purity oxide or carbonate powders. For illustration, in the embodiment of the present 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 oxide or carbonate powders are mixed by ball milling. Specifically, the powders are ball milled in a protective medium at a speed of 300-400 r / min for 8-16 h, such as a speed of 300 r / min, 350 r / min or 400 r / min. The ball milling time can be 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h or 16 h, preferably, the ball milling time is 12 h. Specifically, the protective medium is a volatile organic solvent, such as ethanol.

[0039] Pre-burning mainly converts the mixed powder into an oxidized state and converts the raw material into a clinker. For example, carbonates are decomposed into oxides and carbon dioxide, or organic matter in the mixed powder is removed by pre-burning. The pre-burning temperature is determined based on the decomposition temperature of the oxide or titanate powder used. The pre-burning temperature used in the embodiment of the present invention is 1000-1100°C, and the insulation time is 2.0-10.0h. Preferably, the insulation time is 4h, and the heating rate is not more than 10°C / min, preferably 5°C / min.

[0040] After the pre-sintering is completed, grinding is performed, and the average particle size of the ceramic powder obtained after grinding is 1.0-50.0μm. The present invention limits the average particle size of the ceramic powder and combines the subsequent sintering aid to improve the sintering quality while reducing the sintering temperature to avoid the growth of grains. The size of the grains affects the breakdown strength of the energy storage ceramic. Specifically, when the average particle size is smaller, it is easy to over-burn during the sintering process, resulting in grain growth and reduced activity. The larger the average grain size, the more difficult it is for the elements to diffuse, and it is difficult to form perfect crystals, which affects the performance of the final product. Finally, the average particle size is conducive to adapting to the sintering aid to improve the quality.

[0041] S2: mixing the obtained ceramic powder with a sintering aid, then adding a binder and mixing, and then granulating, screening 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 number of the ceramic powder, for example, it can be 0.8 mol%, 0.9 mol%, 1.0 mol%, 1.1 mol%, 1.2 mol%. And the mixing is carried out by ball milling, and the ball milling process is: ball milling at a speed of 500-800 r / min for 18-30 hours, such as the ball milling speed can be 500 r / min, 600 r / min, 700 r / min, 800 r / min. The ball milling time can be 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h. 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 a mixing process, the sintering aid is coated on the surface of the ceramic powder and deformed under the action of impact force, which helps to improve the subsequent sintering quality, that is, to form grains below 2 μm and increase the breakdown strength Eb of the ceramic powder material.

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

[0044] S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

[0045] The temperature of debinding is 550-650°C, which can be 550°C, 600°C, 650°C, and the debinding time is 2.0-4.0h, which can be 2h, 3h, 4h. Then sintering is performed, the sintering temperature is 1200-1300°C, and the sintering time is 2.0-4.0h. The debinding heating rate does not exceed 8°C / min, and the sintering heating rate does not exceed 10°C / min. Preferably, the sintering is performed by the buried powder method.

[0046] In order to better illustrate the embodiments of the present invention, the present invention is 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 a preparation method thereof, comprising the following steps:

[0049] S1 weighed BaCaSr3BiTi3Nb5SbTaO according to the stoichiometric ratio 30 The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powders. The pre-fired temperature is 1000° C., the pre-fired time is 2 hours, and the average particle size after grinding is 20 μm.

[0050] S2: Mix the obtained ceramic powder with a sintering aid, then add a binder to mix, and then granulate, sieve and shape to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill for ball milling. The ball mill speed is 500r / min and the ball milling time is 24h. The sintering aid is manganese dioxide with a purity of 99.95%, and the amount added is 1mol% of the total amount of powder. Then pour it into a glass culture dish and place it in an oven to dry. The dried powder is ground and mixed with the binder in a mortar, then granulated, and tableted using a tabletting mold with a diameter of 10mm to obtain a ceramic embryo. The binder is a polyvinyl alcohol aqueous solution, and the amount of the binder added is 6wt% of the mass of the ceramic powder.

[0051] S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

[0052] The ceramic green body is placed in a crucible and covered with a layer of ceramic powder for debinding treatment at a debinding temperature of 550°C and a debinding time of 2h. After debinding, the ceramic green body is sintered at a sintering temperature of 1240°C and a sintering time of 3h to obtain a full-filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, which is recorded as SBTN-AB1.

[0053] Example 2

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

[0055] S1 weighed BaCaSr3BiTi3Nb5SbTaO according to the stoichiometric ratio 30 The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powders. The pre-fired temperature is 1050° C., the pre-fired time is 5 hours, and the average particle size after grinding is 1 μm.

[0056] S2: Mix the obtained ceramic powder with a sintering aid, then add a binder to mix, and then granulate, screen and shape to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill for ball milling. The ball mill speed is 600r / min and the ball milling time is 18h. The sintering aid is copper oxide with a purity of 99.95%, and the amount added is 0.8mol% of the total amount of powder. Then pour it into a glass culture dish and place it in an oven to dry. The dried powder and the binder are ground and mixed in a mortar, then granulated, and tableted using a tabletting mold with a diameter of 10mm to obtain a ceramic embryo. The binder is a polyvinyl alcohol aqueous solution, and the amount of the binder added is 5wt% of the mass of the ceramic powder.

[0057] S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

[0058] The ceramic green body is placed in a crucible and covered with a layer of ceramic powder for debinding treatment at a debinding temperature of 600°C and a debinding time of 3h. After debinding, the ceramic green body is sintered at a sintering temperature of 1200°C and a sintering time of 2h to obtain a full-filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, which is recorded as SBTN-AB2.

[0059] Example 3

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

[0061] S1 weighed BaCaSr3BiTi3Nb5SbTaO according to the stoichiometric ratio 30 The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powders. The pre-fired temperature is 1100° C., the pre-fired time is 10 hours, and the average particle size after grinding is 50 μm.

[0062] S2: Mix the obtained ceramic powder with a sintering aid, then add a binder to mix, and then granulate, sieve and shape to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill for ball milling. The ball mill speed is 800r / min and the ball milling time is 30h. The sintering aid is copper oxide with a purity of 99.95%. The amount added is 1.2mol% of the total amount of powder. Then pour it into a glass culture dish and place it in an oven to dry. The dried powder is ground and mixed with the binder in a mortar, then granulated, and tableted using a tabletting mold with a diameter of 10mm to obtain a ceramic embryo. The binder is a polyvinyl alcohol aqueous solution, and the amount of the binder added is 6wt% of the mass of the ceramic powder.

[0063] S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

[0064] The ceramic green body is placed in a crucible and covered with a layer of ceramic powder for debinding treatment at a debinding temperature of 650°C and a debinding time of 4 hours. After debinding, the ceramic green body is sintered at a sintering temperature of 1300°C and a sintering time of 4 hours to obtain a full-filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, which is recorded as SBTN-AB3.

[0065] Example 4

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

[0067] S1 weighed BaCaSr3BiTi3Nb7O according to the stoichiometric ratio 30The oxide or carbonate powders corresponding to the elements are mixed, pre-fired and ground to obtain ceramic powders. The pre-fired temperature is 1000° C., the pre-fired time is 2 hours, and the average particle size after grinding is 20 μm.

[0068] S2: Mix the obtained ceramic powder with a sintering aid, then add a binder to mix, and then granulate, sieve and shape to obtain a ceramic green body. The pre-fired mixed powder and the sintering aid are placed in a nylon ball mill for ball milling. The ball mill speed is 500r / min and the ball milling time is 24h. The sintering aid is manganese dioxide with a purity of 99.95%, and the amount added is 1mol% of the total amount of powder. Then pour it into a glass culture dish and place it in an oven to dry. The dried powder is ground and mixed with the binder in a mortar, then granulated, and tableted using a tabletting mold with a diameter of 10mm to obtain a ceramic embryo. The binder is a polyvinyl alcohol aqueous solution, and the amount of the binder added is 6wt% of the mass of the ceramic powder.

[0069] S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

[0070] The ceramic green body is placed in a crucible and covered with a layer of ceramic powder for debinding treatment at a debinding temperature of 550°C and a debinding time of 2h. After debinding, the ceramic green body is sintered at a sintering temperature of 1220°C and a sintering time of 3h to obtain a full-filled tungsten bronze-based high-entropy ferroelectric energy storage ceramic material, which is recorded as SBTN-A.

[0071] Example 5

[0072] Different from Example 4, the filled tungsten bronze-based high entropy ferroelectric energy storage ceramic material in this embodiment is Sr5BiTi3Nb5SbTaO 30 The prepared filled tungsten bronze-based high entropy ferroelectric energy storage ceramic material is denoted as SBTN-B.

[0073] Comparative Example 1

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

[0075] Comparative Example 2

[0076] Different from 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 recorded as SBTN-AB4.

[0077] Comparative Example 3

[0078] Different from 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, and the prepared filled tungsten bronze-based high entropy ferroelectric energy storage ceramic material is recorded as SBTN-AB5.

[0079] Comparative Example 4

[0080] Different from 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 filled tungsten bronze-based high entropy ferroelectric energy storage ceramic material is recorded as SBTN-AB6.

[0081] Comparative Example 5

[0082] Different from Example 1, in step S2 of this comparative example, the ball milling process is: ball milling at a speed of 400 r / min for 30 hours. The prepared filled tungsten bronze-based high entropy ferroelectric energy storage ceramic material is recorded as SBTN-AB7.

[0083] Performance Characterization

[0084] Since Examples 1, 2 and 3 are similar, and Examples 4 and 5 are similar, Example 1 is selected as the comparative example. There are slight differences in performance between Examples 1 and 2-5 and Example 1, but the differences in the attached drawings are small. Therefore, Example 1, Example 4 and Comparative Example 1 are selected for explanation in conjunction with the attached drawings, and the other examples and comparative examples are explained using test data. X-ray diffraction tests were performed on the filled tungsten bronze-based high entropy ferroelectric energy storage ceramic materials prepared in Example 1, Example 4 and Comparative Example 1, respectively. Figure 1 The X-ray diffraction patterns of Example 1 (SBTN-AB1), Example 4 (SBTN-A) and Comparative Example 1 (SBTN) are shown. Figure 1 It can be seen that the prepared ceramic material has basically no obvious impurities.

[0085] After polishing the surfaces of the ceramic materials prepared in Example 1, Example 4 and Comparative Example 1, the ceramics were placed in an unsealed crucible for thermal corrosion treatment; the thermal corrosion temperature was 1000-1150° C., the heating rate was 7° C. / min, and then a scanning electron microscope was used to take pictures. Figure 2 The scanning electron microscope images of the embodiments and comparative examples are shown in FIG. Figure 2 It can be seen that with the increase of doping substitution ions, the entropy value of the system increases, the grain size becomes smaller and smaller, and the average grain size (G a ) is reduced from 3.42μm for SBTN ceramics to 0.67μm for SBTN-AB1 ceramics. Grain refinement is helpful to improve the breakdown field strength of ceramics.

[0086] The ceramic ground, polished and silver-plated electrodes prepared in Example 1, Example 4 and Comparative Example 1 were sintered at a temperature of 550° C., a heating rate of 2° C. / min, and a holding time of 20 minutes, and then the electrical properties were tested.

[0087] The dielectric properties of the ceramics with electrodes prepared and processed in Example 1, Example 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 in FIG. Figure 3 It can be seen that the increase in entropy value enhances the relaxation behavior of the material, which is manifested in that the phase change of SBTN-AB1 is diffuse in the range of -100℃ to 200℃. The enhancement of relaxivity helps to improve the energy storage performance.

[0088] The ceramics prepared and processed and plated with electrodes in Example 1, Example 4 and Comparative Example 1 were subjected to unipolar hysteresis loop tests. Figure 4 1 is a unipolar hysteresis loop diagram of Example 1 (SBTN-AB1), Example 4 (SBTN-A) and Comparative Example 1 (SBTN). Figure 4 It can be seen from the figure that the introduction of multiple ions at the A and B sites increases the system configuration entropy, which greatly improves the energy storage performance. The effective energy storage density is increased from 2.12 J / cm 3 Improved to 8.9J / cm2 of SBTN-AB1 3 , the breakdown electric field is enhanced from 30kV / mm of SBTN to 86kV / mm of SBTN-AB. At the same time, the increase in effective energy storage density generally increases energy loss, resulting in a decrease in energy storage efficiency. However, the energy storage efficiency of SBTN-A and SBTN-AB1 remains above 90%, thanks to the reduction in polarization hysteresis brought about by the high entropy effect.

[0089] Figure 5 is the temperature and frequency dependent W of SBTN-AB1 ceramic at 60 kV / mm rec and η values, it can be seen that as the temperature rises from 25℃ to 140℃, W rec The η value attenuation does not exceed 10%. In the range of 10Hz to 100Hz, the W of SBTN-AB1 rec The changes of and η with frequency are also very small, and the attenuation does not exceed 10%.

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

[0091] Table 1 Performance test data of 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A filled tungsten bronze structure energy storage ceramic material, characterized in that: The general composition formula of 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 a divalent element, 0≤x≤2, 0≤y≤1, 0≤z≤1; The x, y and z are not all zero.

2. The energy storage ceramic material according to claim 1, characterized in that: A is at least two divalent elements, 1≤x≤2, 0 <y≤1,0<z≤1。 3. The energy storage ceramic material according to claim 1 or 2, characterized in that: The A is one or more of Ba, Ca, and Mg.

4. A method for preparing an energy storage ceramic material as claimed in any one of claims 1 to 3, characterized in that: include: S1 weigh A according to the stoichiometric ratio x Sr 5-x BiTi3Nb 7-y-z Sb y Ta z O 30 The oxide or carbonate powders corresponding to the elements are mixed, pre-sintered and ground to obtain ceramic powders; S2: mixing the obtained ceramic powder with a sintering aid, then adding a binder, mixing, granulating, screening and molding to obtain a ceramic green body; S3: debinding and sintering the ceramic green body to obtain the ceramic green body.

5. The preparation method according to claim 4, characterized in that: The average particle size of the ceramic powder obtained after grinding is 1.0-50.0 μm.

6. The preparation method according to claim 4, characterized in that: The pre-burning temperature is 1000-1100° C. and maintained for 2.0-10.0 hours.

7. The preparation method according to claim 4, characterized in that: In step S1, the mixing is performed by ball milling at a rotation speed of 300-400 r / min for 8-16 hours in a protective medium.

8. The preparation method according to claim 4, characterized in that: The added amount of the sintering aid is 1 mol% of the total molar number of the ceramic powder.

9. The preparation method according to claim 8, characterized in that: The ceramic powder and the sintering aid are mixed by ball milling process, wherein the ball milling process is: ball milling at a speed of 500-800 / min for 18-30 hours.

10. The preparation method according to claim 4, characterized in that: In step S3, the debinding temperature is 550-650° C., the debinding time is 2.0-4.0 hours, and then sintering is performed at a sintering temperature of 1200-1300° C. and a sintering time of 2.0-4.0 hours.

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