Tungsten bronze energy storage ceramic and preparation method thereof

Abstract

The invention belongs to the field of new energy power systems, pulse power technologies and high-temperature electronic devices, and particularly relates to tungsten bronze energy storage ceramic and a preparation method thereof.The tungsten bronze energy storage ceramic has the chemical formula of Gd < 0.03 > Ba < 0.47 > Sr < 0.485-1.5 x > Bi < x > NbO6, and x ranges from 0.02 to 0.06. The tungsten bronze energy storage ceramic has the energy storage density of 1.6-2.57 J / cm < 3 > and the energy storage efficiency of 75.36%-96.22% under the voltage of 215 kV / cm, and has an excellent energy storage coefficient (Wre / E = 0.012 J cm <-2 > kV <-1 >). And the requirement that the electronic capacitor operates in a low electric field at present is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new energy power systems, pulse power technology and high-temperature electronic devices, and particularly relates to a tungsten bronze energy storage ceramic and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy power systems, pulse power technology and high-temperature electronic devices, dielectric materials with high energy storage density have attracted extensive attention. Compared with other energy storage devices, dielectric capacitors are widely used in various high-tech fields, including medical devices, military systems and hybrid electric vehicles, due to their high power density and fast charging / discharging rate. Generally, in the field of microelectronics and consumer electronics, devices are usually operated at relatively low voltages, which makes it neither practical nor necessary to use extreme electric fields, so it is crucial for practical applications to achieve excellent energy storage performance under low electric field conditions. However, the relatively low recoverable energy storage density ( W rec ) and low energy storage efficiency ( η ) of most perovskite structure energy storage capacitors under low electric field limit further applications. As the second largest category of dielectric ceramics in addition to perovskite structure, tungsten bronze (TTB) ceramics have attracted increasing attention due to their rich physical properties, such as unique ferroelectric phase transition and excellent dielectric and polarization properties. However, the energy storage density and energy storage efficiency of the current tungsten bronze (TTB) ceramics in the low electric field range are not high enough, which limits their application. SUMMARY

[0003] To solve the problems in the prior art, the purpose of the present application is to provide a tungsten bronze energy storage ceramic and a preparation method thereof, which can have a large energy storage density and energy storage efficiency in the low electric field range.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A tungsten bronze energy storage ceramic, whose chemical formula is Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6, wherein, x The value is 0.02-0.06.

[0005] The present application also provides a preparation method of the tungsten bronze energy storage ceramic as described above, comprising the following steps: According to the chemical proportion of each element of the tungsten bronze energy storage ceramic, the raw material powders of the tungsten bronze energy storage ceramic are uniformly mixed to obtain mixed raw material powders; Sintering the mixed raw material powder in an air environment at 1000-1100℃ for 2-3 hours, and after furnace cooling, processing the powder to obtain a sintered material A; Ball-milling, drying, granulating the sintered material A, and making a green body by isostatic pressing; Secondary sintering the green body, and during secondary sintering, sintering the green body in an air environment at 1250-1350℃ for 2-3 hours, and then furnace cooling to obtain the prepared tungsten bronze energy storage ceramic.

[0006] Preferably, the method for preparing the tungsten bronze energy storage ceramic further comprises: First, drying each raw material powder of the tungsten bronze energy storage ceramic at 60-100℃ for 4-8 hours to remove water, and then uniformly mixing each raw material powder of the tungsten bronze energy storage ceramic.

[0007] Preferably, uniformly mixing each raw material powder of the tungsten bronze energy storage ceramic specifically comprises: Mixing each raw material powder of the tungsten bronze energy storage ceramic, then adding anhydrous ethanol to cover the raw material powder, and then performing primary ball-milling to obtain a mixed material A; wherein the rotation speed of the primary ball-milling is 200-400r / min, and the primary ball-milling time is 12-24 hours. Drying the mixed material A at 80-120℃ for 4-8 hours to remove the anhydrous ethanol, and then grinding the mixed material uniformly and sieving to obtain the mixed raw material powder.

[0008] Preferably, when ball-milling the sintered material A, the process comprises: Adding anhydrous ethanol to the sintered material A to cover the sintered material A, and then performing secondary ball-milling to obtain a mixed material C; wherein the rotation speed of the secondary ball-milling is 200-400r / min, and the secondary ball-milling time is 12-24 hours.

[0009] Preferably, after ball-milling and drying the sintered material A, the process of granulation comprises: After ball-milling and drying the sintered material A, adding a binder to perform granulation to obtain raw material particles.

[0010] Preferably, after ball-milling, drying, and granulating the sintered material A, the process of making a green body by isostatic pressing comprises: Heating the raw material particles to 120-150℃ under a pressure of 180-200MPa for 0.5-1h to remove water, and then heating to 550-600℃ for 3-5h to remove the binder to obtain the green body.

[0011] Preferably, the heating rate is controlled at 1-2℃ / min.

[0012] Preferably, the adhesive is polyvinyl alcohol, and the amount of the adhesive is 6%-8% of the mass of the sintering material A.

[0013] Preferably, the raw material powder of the tungsten bronze energy storage ceramic comprises Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder.

[0014] The present application has the following advantages: As Figure 1 shown, for a typical tungsten bronze structure Ba 0.47 Sr 0.53 NbO6, doping Bi at A site aims to increase lattice vacancies, which can enhance dielectric polarization and breakdown strength (this can be obtained by defect reaction: ). In addition, the stereochemically active lone pair of electrons of Bi 3+ will promote hybridization with O2-2p orbital, further enhancing A-site polarization. This leads to higher maximum polarization ( P max ) and breakdown strength, while reducing remnant polarization ( P r ) and dielectric loss, ultimately improving energy storage efficiency. The tungsten bronze energy storage ceramic of the present application has an energy storage density of 1.6-2.57 J / cm 3 and an energy storage efficiency of 75.36%-96.22% at a voltage of 215 kV / cm, as well as an excellent energy storage coefficient ( W rec / E = 0.012 J cm -2 kV -1 ). It meets the current demand for electronic capacitors to operate at low electric fields. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Figure 1 is a schematic diagram of the present application for optimizing the energy storage performance of the tungsten bronze energy storage ceramic.

[0016] Figure 2 Figure 2 is a scanning electron microscope image of the tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.425 Bi 0.04 NbO of the present application. θ ~2 θ

[0017] Figure 3(a) is a scanning electron microscope image of the tungsten bronze energy storage ceramic of Comparative Example 1 of the present application.

[0018] Figure 3(b) is a scanning electron microscope image of the tungsten bronze energy storage ceramic of Example 1 of the present application.

[0019] ​Fig. 3(c) is a scanning electron microscope photo of the tungsten bronze energy storage ceramic obtained in Example 2 of the present application.

[0020] Fig. 3(d) is a scanning electron microscope photo of the tungsten bronze energy storage ceramic obtained in Example 3 of the present application.

[0021] Fig. 4(a) is a P-E loop diagram of the tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.425 Bi 0.04 NbO3 obtained in Example 2 of the present application.

[0022] Fig. 4(b) is a trend chart of the energy storage performance of the tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.425 Bi 0.04 NbO3 obtained in Example 2 of the present application.

[0023] Fig. 5(a) is a trend chart of the energy storage performance of the tungsten bronze energy storage ceramic obtained in Example 2 of the present application in a wide temperature range.

[0024] Fig. 5(b) is a trend chart of the energy storage performance of the tungsten bronze energy storage ceramic obtained in Example 2 of the present application in a variable frequency range. DETAILED DESCRIPTION

[0025] The present application will be further described by the following examples, it should be noted that the examples are only an embodiment of the present application for specific conditions, and do not limit the present application in any way, any simple modification, change and other changes according to the technical essence of the present application are within the protection scope of the present application.

[0026] The chemical formula of the tungsten bronze energy storage ceramic of the present application is as follows: Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6, wherein, x =0.02, 0.04, 0.06.

[0027] As Figure 1 shown, in the present application, the rare earth Gd 3+ (with a relatively high valence state) is introduced to replace Sr 2+ at A site, so as to adjust the relaxation behavior and effectively enhance the ferroelectric polarization. At the same time, Bi is doped at A site, aiming to increase the lattice vacancies, so as to enhance the dielectric polarization and breakdown strength. At the same time, the stereochemical active lone pair electrons of Bi 3+ are utilized to further enhance the maximum polarization (Pmax) P max ) and the breakdown strength, while reducing the remanent polarization (Pr) and the loss (tanδ).P r ) and dielectric loss, ultimately improving the energy storage efficiency.

[0028] The preparation method of the tungsten bronze energy storage ceramic according to the present application comprises the following steps: Step 1, after weighing the Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder according to the chemical formula of the tungsten bronze energy storage ceramic, cover them with tin paper, and dry them at 60-100℃ for 4-8 hours to remove the water in the raw material powders. Step 2, mix the dried Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder, add anhydrous ethanol to cover the raw material powders, and then perform primary ball milling at a speed of 200-400r / min for 12-24 hours to obtain a mixed material A.

[0029] Step 3, place the mixed material A in a drying box at 80-120℃ for 4-8 hours to remove the anhydrous ethanol, then grind the mixed material uniformly, and sieve it to obtain a mixed material B.

[0030] Step 4, place the mixed material B in an alumina crucible for sintering: specifically, sinter it at 1000-1100℃ in an air environment for 2-3 hours, grind it uniformly after cooling in the furnace, and sieve it to obtain a sintered material A. Step 4, add anhydrous ethanol to cover the sintered material A, and then perform secondary ball milling at a speed of 200-400r / min for 12-24 hours to obtain a mixed material C.

[0031] Step 5, dry the mixed material C, sieve it, and then add polyvinyl alcohol (PVA) for granulation to obtain raw material granules; wherein the amount of polyvinyl alcohol (PVA) added is 6%-8% of the mass of the mixed material C.

[0032] Step 6, prepare a green body from the raw material granules by isostatic pressing; wherein, during the isostatic pressing process, the temperature is raised to 120-150℃ at a rate of 1-2℃ / min under a pressure of 180-200MPa, then the temperature is kept for 0.5-1h to remove the water, and then the temperature is raised to 550-600℃ at a rate of 1-2℃ / min, and kept for 3-5h to remove the PVA binder, thereby obtaining the green body.

[0033] Step 7, perform secondary sintering on the green body; when secondary sintering, the green body is sintered at 1250-1350℃ in an air environment for 2-3 hours, and then cooled in the furnace to obtain the prepared tungsten bronze energy storage ceramic.

[0034] After the ceramic with high energy storage performance at low electric field of the present application is obtained, structure and performance test is conducted, during the test, the surface of the sample is polished and Pt electrode is sprayed, and microstructure test and electrical performance test are conducted.

[0035] In the following examples and comparative examples of the present application, 4-5N grade Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O are used.

[0036] Comparative Example 1 The chemical formula of the tungsten bronze energy storage ceramic of the present comparative example is: Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6 (wherein, x =0), and the preparation method comprises the following steps: Step 1, after the Gd2O3 powder, BaCO3 powder, SrCO3 powder and Nb2O powder are weighed according to the chemical formula of the tungsten bronze energy storage ceramic, tin paper is covered, and the water in the raw material powder is removed by drying at 100℃ for 8 hours; Step 2, the dried Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder are mixed, anhydrous ethanol is added to cover the raw material powder, and then primary ball milling is conducted to obtain a mixed material A; wherein the rotation speed of the primary ball milling is 300r / min, and the primary ball milling time is 18 hours.

[0037] Step 3, the mixed material A is placed in a 80℃ drying box for drying for 8h, and then the anhydrous ethanol is removed, and the mixed material is ground uniformly and sieved to obtain a mixed material B.

[0038] Step 4, the mixed material B is placed in an alumina crucible for sintering: specifically, sintering is conducted at 1000℃ in an air environment for 2.5 hours, and after cooling in the furnace, the sintered material A is obtained by uniformly grinding and sieving; Step 4, anhydrous ethanol is added to cover the sintered material A, and then secondary ball milling is conducted to obtain a mixed material C; wherein the rotation speed of the secondary ball milling is 300r / min, and the secondary ball milling time is 18 hours.

[0039] Step 5, the mixed material C is dried and sieved, and then polyvinyl alcohol (PVA) is added for granulation to obtain raw material particles; wherein the addition amount of polyvinyl alcohol (PVA) is 8% of the mass of the mixed material C.

[0040] Step 6, the raw material particles are made into a green body by isostatic pressing; wherein, in the isostatic pressing process, the temperature is raised to 130℃ at a temperature raising rate of 1-2℃ / min under a pressure of 180MPa, then the temperature is kept for 40min to remove the water, then the temperature is raised to 580℃ at a temperature raising rate of 1-2℃ / min, and kept for 4h to remove the PVA binder, so as to obtain the green body.

[0041] Step 7, the green body is subjected to secondary sintering; wherein, the green body is sintered in an air environment at 1250℃ for 3h, and then cooled in the furnace to obtain the prepared tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.485 NbO6.

[0042] The high energy storage ceramic prepared in the present comparative example is of tungsten bronze structure, and the energy storage density thereof can reach 0.82 J / cm 3 , the energy storage efficiency thereof reaches 38.76%, and the microstructure thereof is good.

[0043] Example 1 The chemical formula of the tungsten bronze energy storage ceramic of the present example is: Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6(wherein, x =0.02), and the preparation method thereof comprises the following steps: Step 1, Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder are weighed according to the chemical formula of the tungsten bronze energy storage ceramic, then covered with tin paper, and dried at 100℃ for 8h to remove the water in the raw material powders; Step 2, the dried Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder are mixed, anhydrous ethanol is added to cover the raw material powders, and then subjected to primary ball milling to obtain a mixed material A; wherein, the rotation speed of the primary ball milling is 300r / min, and the primary ball milling time is 18h.

[0044] Step 3, the mixed material A is placed in a 80℃ drying oven for drying for 8h to remove the anhydrous ethanol, and then ground uniformly and sieved to obtain a mixed material B.

[0045] Step 4, the mixed material B is placed in an alumina crucible for sintering; specifically, sintered in an air environment at 1000℃ for 2.5h, and then cooled in the furnace, ground uniformly, and sieved to obtain a sintered material A; Step 4, add anhydrous ethanol to the sintering material A, so that the anhydrous ethanol covers the sintering material A, and then perform secondary ball milling to obtain a mixture C; wherein the secondary ball milling speed is 300 r / min, and the secondary ball milling time is 18 hours.

[0046] Step 5, dry the mixture C, sieve, and then add polyvinyl alcohol (PVA) for granulation to obtain raw material particles; wherein the addition amount of the polyvinyl alcohol (PVA) is 8% of the mass of the mixture C.

[0047] Step 6, prepare a green body from the raw material particles by isostatic pressing; wherein in the isostatic pressing process, under the condition of a pressure of 180 MPa, the temperature is raised to 130℃ at a temperature raising rate of 1-2℃ / min, then the temperature is kept for 40 min to remove water, and then the temperature is raised to 580℃ at a temperature raising rate of 1-2℃ / min, and kept for 4 h to remove the PVA binder, to obtain the green body.

[0048] Step 7, perform secondary sintering on the green body. In the secondary sintering, the green body is sintered in an air environment at 1250℃ for 3 hours, and then cooled in the furnace to obtain the prepared tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.455 Bi 0.02 NbO6.

[0049] The high energy storage ceramic prepared in this embodiment has a tungsten bronze structure, and the energy storage density can reach 1.60 J / cm 3 , the energy storage efficiency reaches 75.36%, and the microstructure is good.

[0050] Example 2 The chemical formula of the tungsten bronze energy storage ceramic of this embodiment is: Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6(wherein, x =0.04), and the preparation method comprises the following steps: Step 1, weigh Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder according to the chemical formula of the tungsten bronze energy storage ceramic, cover with tin paper, and dry at 80℃ for 6 hours to remove water in the raw material powders; Step 2, mix the dried Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder, add anhydrous ethanol to cover the raw material powders, and then perform primary ball milling to obtain a mixture A; wherein the primary ball milling speed is 400 r / min, and the primary ball milling time is 24 hours.

[0051] Step 3, put the mixture A into a drying oven at 100℃ for 6h to remove the absolute ethyl alcohol, then grind the mixture evenly, sieve, to get mixture B.

[0052] Step 4, put the mixture B into an alumina crucible for sintering: specifically, sinter at 1100℃ for 3h in air environment, then grind the mixture evenly, sieve, to get sintered material A; Step 4, add absolute ethyl alcohol to the sintered material A, so that the absolute ethyl alcohol covers the sintered material A, then perform secondary ball milling to get mixture C; wherein the secondary ball milling speed is 400r / min, and the secondary ball milling time is 24h.

[0053] Step 5, dry the mixture C, sieve, then add polyvinyl alcohol (PVA) for granulation to get raw material particles; wherein the amount of polyvinyl alcohol (PVA) added is 6% of the mass of the mixture C.

[0054] Step 6, make the green body by isostatic pressing from the raw material particles; wherein in the isostatic pressing process, under the condition of a pressure of 200MPa, heat to 120℃ at a heating rate of 1-2℃ / min, then keep the temperature for 1h to remove water, then heat to 600℃ at a heating rate of 1-2℃ / min, keep the temperature for 3h to remove the PVA binder, to get the green body.

[0055] Step 7, perform secondary sintering on the green body. In the secondary sintering, sinter the green body at 1300℃ for 2h in air environment, then cool down with the furnace to get the prepared tungsten bronze energy storage ceramic Gd 0.03 Ba 0.47 Sr 0.425 Bi 0.04 NbO6.

[0056] The high energy storage ceramic prepared in this embodiment is of tungsten bronze structure, and its energy storage density can reach 2.57 J / cm 3 , the energy storage efficiency reaches 81.54%, and it has good stability in the temperature range of 30~125℃ and the frequency range of 1~1000Hz.

[0057] Example 3 The chemical formula of the tungsten bronze energy storage ceramic in this embodiment is: Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6(wherein, x =0.06), and its preparation method comprises the following steps: Step 1: Weigh Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder according to the chemical formula of tungsten bronze energy storage ceramic, cover with tin foil, and dry at 60°C for 4 hours to remove moisture from these raw material powders. Step 2: Mix the dried Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder and Nb2O powder, add anhydrous ethanol to cover the raw material powders, and then perform a ball milling to obtain mixture A; wherein, the ball milling speed is 200 r / min and the ball milling time is 12 hours.

[0058] Step 3: Place the mixture A in a drying oven at 120 ℃ and dry for 4 hours to remove anhydrous ethanol. Then grind the mixture evenly and sieve it to obtain mixture B.

[0059] Step 4: Place the mixture B in an alumina crucible for sintering: Specifically, sinter at 1050°C in air for 2 hours, cool with the furnace, grind evenly, and sieve to obtain sintered material A. Step 4: Add anhydrous ethanol to the sintered material A, ensuring the anhydrous ethanol completely covers the sintered material A, and then perform a second ball milling to obtain mixture C; wherein, the second ball milling speed is 200 r / min, and the second ball milling time is 12 hours.

[0060] Step 5: Dry the mixture C, sieve it, and then add polyvinyl alcohol (PVA) to granulate it to obtain raw material granules; wherein, the amount of polyvinyl alcohol (PVA) added is 7% of the mass of the mixture C.

[0061] Step 6: The raw material particles are made into green blanks by isostatic pressing; wherein, during the isostatic pressing process, the temperature is raised to 150°C at a heating rate of 1-2°C / min under a pressure of 190MPa, and then held at that temperature for 0.5h to remove moisture, and then raised to 550°C at a heating rate of 1-2°C / min and held at that temperature for 5h to remove PVA adhesive, thereby obtaining the green blanks.

[0062] Step 7: The green body is subjected to secondary sintering. During the secondary sintering, the green body is sintered in air at 1350 °C for 2.5 hours, and then cooled in the furnace to obtain the prepared tungsten bronze energy storage ceramic Gd. 0.03 Ba 0.47 Sr 0.395 Bi 0.06 NbO6.

[0063] The high-energy-storage ceramic prepared in this embodiment has a tungsten bronze structure and its energy storage density can reach 2.35 J / cm³. 3 It has an energy storage efficiency of 96.22% and a good microstructure.

[0064] The obtained material properties: Figure 2 The ceramics prepared for the comparative examples and various embodiments of the present invention θ ~2 θ Scanning images show that all prepared ceramics are single-phase tungsten bronze structure ceramics, with no second phase present.

[0065] Figures 3(a)-3(d) are scanning electron microscope images of the ceramics prepared in the comparative example and various embodiments of the present invention. It can be seen that as... x With the increase of , the grain size decreased from 2.82 µm to 2.25 µm, and then increased to 2.94 µm, showing a trend of first decreasing and then increasing, which helps to control the breakdown field strength of ceramics.

[0066] Figures 4(a) to 4(b) show the electrical properties of the ceramics prepared in the comparative example and various embodiments of the present invention. It can be seen that, with... x With the increase in energy density and energy efficiency, the energy storage density and energy storage efficiency increased from 0.82 J / cm³. 3 Increased to 2.57 J / cm 3 It then decreased to 2.35 J / cm. 3 It shows a trend of first decreasing and then increasing. x When the value is 0.04 (i.e., in Embodiment 2 of the present invention), it has 2.57 J / cm. 3 Its high energy density and 81.54% energy storage efficiency indicate that it has excellent energy storage performance under low electric field conditions.

[0067] Figures 5(a) and 5(b) show the recoverable energy density of Embodiment 2 of the present invention within a wide temperature range of 20-125℃ and a frequency conversion range of 1-1000Hz. W rec =1.17J / cm 3 ) and energy storage efficiency ( η =88.9%) remained almost unchanged, with fluctuations relative to room temperature of less than 10.4%. The trend of changes in energy storage density and energy efficiency of the tungsten bronze structure ceramic involved in this invention: It was found that the ceramic involved in this invention has excellent temperature stability and frequency stability, and has great potential and advantages in the low electric field range.

[0068] The results above show that the tungsten bronze structure energy storage ceramic involved in this invention exhibits 2.57 J / cm² under a low electric field of 215 kV / cm. 3With its high energy density and 81.54% energy storage efficiency, this invention can be used in high-tech fields, including medical devices, military systems, and hybrid vehicles. Furthermore, the high-entropy ceramic of this invention is a lead-free ceramic, avoiding the environmental and human health hazards of traditional Pb-based ceramics, and meeting the environmental protection requirements of modern industrial production.

[0069] The Gd of the present invention 0.03 Ba 0.47 Sr 0.485-1.5x Bi x The advantages of NbO6 high-entropy ceramics include at least the following aspects: (1) Simple process. The tungsten blue ceramic is produced by sintering ceramics through simple processes such as ball milling and sintering. It has the advantages of simple structure and simple process.

[0070] (2) Good temperature stability. As can be seen, the coefficient of thermal expansion and the thermal conductivity of the sample remain at a relatively stable level as the temperature increases.

[0071] As described above, many different embodiments can be constructed without departing from the spirit and scope of the invention. It should be understood that the invention is not limited to the specific examples described in the specification, except as defined in the appended claims.

[0072] (1) One advantage of the present invention is that the preparation method is simple to operate, has high preparation efficiency and product qualification rate, and has good application and promotion potential.

[0073] (2) The reagents and raw materials of this invention are all commercially available. (3) The present invention provides a tungsten bronze energy storage ceramic under low electric field, which is free of volatile and harmful elements, has stable performance and is environmentally friendly.

[0074] (4) The tungsten bronze energy storage ceramic under low electric field provided by the present invention has good temperature stability. (5) More importantly, the principle of reducing the thermal conductivity of ceramic materials in this invention has the potential to be extended to other materials. Based on this principle, it is possible to discover tungsten bronze ceramic materials with excellent energy storage performance under low electric fields that meet various performance requirements in high-tech fields, including medical equipment, military systems and hybrid vehicles.

[0075] The tungsten bronze energy storage ceramic provided by this invention possesses comprehensive performance characteristics including high energy density, high energy storage efficiency, and excellent temperature stability, making it widely applicable in fields such as medical equipment, military systems, and hybrid vehicles. Furthermore, this tungsten bronze ceramic is a lead-free ceramic, avoiding the environmental and human health hazards associated with traditional Pb-based ceramics, and meeting the environmental protection requirements of modern industrial production.

[0076] The above is merely one specific embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the scope of protection of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A tungsten bronze energy storage ceramic, characterized in that, Its chemical formula is Gd 0.03 Ba 0.47 Sr 0.485-1.5x Bi x NbO6, of which x The value ranges from 0.02 to 0.

06.

2. The method for preparing a tungsten bronze energy storage ceramic according to claim 1, characterized in that, Includes the following steps: According to the chemical ratio of each element in tungsten bronze energy storage ceramic, the raw material powders of tungsten bronze energy storage ceramic are mixed evenly to obtain mixed raw material powder. The mixed raw material powder is sintered in an air environment at 1000-1100℃ for 2-3 hours, and then cooled in the furnace and processed into powder to obtain sintered material A; The sintered material A is ball-milled, dried, granulated, and then pressed into a green body by isostatic pressing. The green blank is subjected to secondary sintering. During the secondary sintering, the green blank is sintered in an air environment at 1250-1350 °C for 2-3 hours, and then cooled in the furnace to obtain the tungsten bronze energy storage ceramic.

3. The method for preparing a tungsten bronze energy storage ceramic according to claim 2, characterized in that, Also includes: First, dry the raw material powders of tungsten bronze energy storage ceramics at 60-100℃ for 4-8 hours to remove moisture, and then mix the raw material powders of tungsten bronze energy storage ceramics evenly.

4. The method for preparing a tungsten bronze energy storage ceramic according to claim 2, characterized in that, The various raw material powders for tungsten bronze energy storage ceramics are mixed evenly, specifically including: Mix the raw material powders of tungsten bronze energy storage ceramic, then add anhydrous ethanol to cover the raw material powder, and then perform ball milling once to obtain mixture A; wherein, the ball milling speed is 200-400 r / min and the ball milling time is 12-24 hours. The mixture A is dried at 80-120 ℃ for 4-8 hours to remove anhydrous ethanol. Then the mixture is ground evenly and sieved to obtain the mixed raw material powder.

5. The method for preparing a tungsten bronze energy storage ceramic according to claim 2, characterized in that, When the sintered material A is ball-milled, the following process is included: Anhydrous ethanol is added to the sintered material A to ensure that the ethanol completely covers the sintered material A, and then a second ball milling is performed to obtain a mixture C; wherein the second ball milling speed is 200-400 r / min and the second ball milling time is 12-24 hours.

6. The method for preparing a tungsten bronze energy storage ceramic according to claim 2, characterized in that, The granulation process after ball milling and drying of the sintered material A includes: After ball milling and drying, the sintered material A is granulated by adding a binder to obtain raw material particles.

7. The method for preparing a tungsten bronze energy storage ceramic according to claim 6, characterized in that, The process of preparing green bodies from the sintered material A by ball milling, drying, granulation, and isostatic pressing includes: The raw material particles are heated to 120-150℃ under 180-200MPa conditions and held for 0.5-1h to remove moisture; then heated to 550-600℃ and held for 3-5h to remove the binder, thus obtaining the green body.

8. The method for preparing a tungsten bronze energy storage ceramic according to claim 7, characterized in that, The heating rate is controlled at 1-2℃ / min.

9. The method for preparing a tungsten bronze energy storage ceramic according to any one of claims 6-8, characterized in that, The adhesive is polyvinyl alcohol, and the amount of adhesive added is 6%-8% of the mass of sintering material A.

10. The method for preparing a tungsten bronze energy storage ceramic according to claim 9, characterized in that, The raw material powders for tungsten bronze energy storage ceramics include Gd2O3 powder, BaCO3 powder, SrCO3 powder, Bi2O3 powder, and Nb2O powder.

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