High-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer energy-storage ceramic capacitor and preparation method thereof

Abstract

The invention relates to a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer energy-storage ceramic capacitor and a preparation method thereof, the chemical general formula of the capacitor is (Na < 0.75-x > Bi < 0.125 > Li < 0.125 > Nb < 0.75-xy-xz > Ti < 0.25 >)-xBa (PyQz) O3, x is more than or equal to 0.01 and less than or equal to 0.06, and x is more than or equal to 0.01 and less than or equal to 0.06. Y is greater than or equal to 0.01 and less than or equal to 0.02; the value range of z is more than or equal to 0.01 and less than or equal to 0.04, P is one or a combination of more than one of Mg, Ni, Ta and Sb, Q is one or a combination of more than one of Mn, Nb and Zr, the average grain size of the energy storage ceramic capacitor is in a micron order, the average thickness of the dielectric layer is 8-15 microns, and the capacitor can release energy storage density (Wrecc) gt; the energy storage efficiency (eta) is greater than 85%; the change rate of Wrec and eta in the test temperature range of 20-200 DEG C is less than 8%; and the change rate of Wrec and eta in the test frequency range of 0.5-240 Hz is less than 6%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage ceramics, and relates to a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer energy storage ceramic capacitor and a preparation method thereof. BACKGROUND

[0002] With the development of electronic circuits towards miniaturization, integration and multifunction, the development of new energy materials with high energy storage density and energy storage efficiency is the key foundation for the development of high-power dielectric ceramic capacitors, and plays an important role in promoting the development of advanced electronic power systems, pulse power devices and new energy vehicles. The dielectric ceramic capacitor based on electrostatic energy storage mechanism has significant advantages such as nanosecond charging and discharging rate and megawatt power density, but its relatively low energy storage capacity seriously limits its miniaturization and lightweight application. Therefore, the development of energy storage density (W rec ) and high conversion efficiency (η) is the core direction of the research and development of the next generation of high-performance dielectric ceramic capacitors.

[0003] The lead-free ceramic material of perovskite structure NaNbO3 (NN) has the advantages of large band gap, high polarization strength, low bulk density and green environmental protection, and is considered as an ideal material system for dielectric energy storage capacitors. In recent years, researchers have reduced the residual polarization, improved the polarization difference and enhanced the breakdown field strength through ion doping substitution, grain size control, antiferroelectric / ferroelectric property control and construction of hetero-domain coexistence structure, so that the energy storage performance of the NN-based ceramic has been greatly optimized, and the energy storage density and energy storage efficiency have been significantly improved.

[0004] However, the energy storage density W rec of the material in the main research reports at present is all lower than 12 J / cm 3 , so the further improvement of the energy storage density W rec is the top priority for the development of advanced energy storage capacitors. In addition, the actual application scenario exists the case of change of environmental temperature, so the temperature stability of the energy storage performance is also an important index of the energy storage ceramic capacitor. In summary, the development of the high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer energy storage ceramic capacitor has important promoting significance for the development and practicalization of high-performance energy storage capacitors. SUMMARY

[0005] Therefore, the application provides a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer energy storage ceramic capacitor and a preparation method thereof to solve the problems of low energy storage performance and insufficient temperature stability of the energy storage performance of the perovskite structure NaNbO3 (NN) based lead-free ceramic material prepared by the prior art, which affects the actual application scenario.

[0006] To achieve the above purpose, the application provides the following technical scheme:

[0007] A high energy storage sodium niobate-based temperature-stable ferroelectric multilayer energy storage ceramic capacitor, the chemical general formula of the energy storage ceramic capacitor is (Na 0.75-x Bi 0.125 Li 0.125 Nb 0.75-xy-xz Ti 0.25 )-xBa(P y Q z )O3, wherein the value range of x is: 0.01≤x≤0.06; the value range of y is: 0.01≤y≤0.02; the value range of z is: 0.01≤z≤0.04, P is one or a combination of several of Mg, Ni, Ta and Sb, Q is one or a combination of several of Mn, Nb and Zr.

[0008] Further, the average grain size of the energy storage ceramic capacitor is in microns, the relative density is higher than 97%, the average thickness of the dielectric layer is 8-15 μm, the releasable energy storage density (W rec ) is >15 J / cm 3 , the energy storage efficiency (η) is greater than 85%; the W o and η change rate is less than 8% in the test temperature range of 20 o C~140 rec C; the W rec and η change rate is less than 6% in the test frequency range of 0.5 Hz~240 Hz.

[0009] The preparation method of the high energy storage sodium niobate-based temperature-stable ferroelectric multilayer energy storage ceramic capacitor, comprising the following steps:

[0010] S1, preparing a sodium niobate-based ferroelectric ceramic thick film material powder;

[0011] S2, preparing a cast thick film based on the powder prepared in step S1;

[0012] S3, combining the cast thick film prepared in step S2 and the powder prepared in step S1 to prepare a multilayer energy storage ceramic capacitor.

[0013] Further, step S1 specifically comprises the following steps:

[0014] S11, according to the chemical general formula (Na 0.75-x Bi 0.125 Li 0.125 Nb 0.75-xy-xz Ti 0.25 )-xBa(P y Q zThe stoichiometric ratio of O3 is as follows: Na2CO3 powder, Nb2O5 powder, Bi2O3 powder, Li2CO3 powder, BaCO3 powder, TiO2 powder, P oxide powder, and Q oxide powder are used as raw materials, wherein the value of x is in the range of 0.01≤x≤0.06; the value of y is in the range of 0.01≤y≤0.02; and the value of z is in the range of 0.01≤z≤0.04. The P oxide powder is one or a combination of several of 5MgCO3·Mg(OH)2·5H2O, NiO, Ta2O5, and Sb2O5, and the Q oxide powder is one or a combination of several of MnO2, Nb2O5, and ZrO2. The purity of all raw materials is ≥99%.

[0015] S12. Using anhydrous ethanol as solvent and zirconium balls as grinding media, the weighed raw material powders Na2CO3 powder, Nb2O5 powder, Bi2O3 powder, Li2CO3 powder, BaCO3 powder, TiO2 powder, P oxide powder and Q oxide powder from step S11 are ball-milled and mixed, and then dried to obtain mixed raw materials.

[0016] S13, according to 3 o C / min ~10 o The heating rate was increased to 750 °C / min to heat the mixed raw material obtained from drying in step S12. o C~900 o C, and at 750 o C~900 o Pre-calcination at temperature C for 3-7 h yields sodium niobate-based ferroelectric ceramic pre-calcined powder.

[0017] S14. The sodium niobate-based ferroelectric ceramic pre-sintered powder obtained in step S13 is subjected to secondary ball milling and dried to obtain sodium niobate-based ferroelectric ceramic powder; the sodium niobate-based ferroelectric ceramic powder is a pure perovskite phase and the particle size is in the submicron range.

[0018] Further, step S2 specifically involves: ball milling and mixing the sodium niobate-based ferroelectric ceramic powder, solvent, dispersant, binder, and plasticizer obtained in step S14; vacuum degassing the uniformly mixed slurry to obtain a casting slurry; casting the casting slurry on a casting machine at a speed of 0.5~1.5 m / min; and drying to obtain a casting film with a thickness of approximately 8-50 μm.

[0019] Furthermore, step S3 specifically includes the following steps:

[0020] S31. Cut the cast film obtained in step S2 into films, use the films according to the designed thickness of the dielectric layer, print the internal electrode paste on the surface of the dielectric layer, and hot press at a temperature of 20°C. o C~70 oUnder conditions of C and pressure of 5 MPa to 50 MPa, the medium layer is hot-pressed and cross-laminated, and then blank films are stacked on the upper and lower surfaces of the stacked medium layer as protective layers to obtain the green blank.

[0021] S32, when the hot water temperature is 20 o C~70 o Under conditions of C and pressure of 5 MPa to 50 MPa, the green blank obtained in step S31 is warm isostatically pressed for 3-60 min to obtain the warm isostatically pressed green blank.

[0022] S33, according to a heating rate of 0.1 o C / min~3 o C / min, the warm isostatic pressing embryo from step S32 is heated to 400 o C-700 o C, and in 400 o C-700 o Insulate at C temperature and remove adhesive for 1-20 hours;

[0023] S34. Place the multi-layer ceramic green body after debinding in step S33 into a double-layer alumina sealed crucible, and use the sodium niobate-based ferroelectric ceramic powder obtained in step S14 to bury the multi-layer ceramic green body, with a density of 2... o C / min ~10 o Heating rate increased to 1000 °C / min o C-1300 o C, and at a temperature of 1000 o C-1300 o Sintering at temperature C for 2-6 hours yields multilayer ceramic blocks.

[0024] S35. After polishing the end electrode surface of the multilayer ceramic block obtained by sintering in step S34, apply end electrode slurry, and heat at a rate of 2... o C / min ~10 o Heating rate increased to 400 °C / min o C-600 o C, and in 400 o C-600 o Under temperature conditions of C, the end is sintered for 15-60 minutes to obtain a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor.

[0025] Furthermore, in step S12, the mass ratio of raw material powder:zirconium balls: anhydrous ethanol is 1:2:1; the ball milling speed is 260~400 r / min, the ball milling is carried out for 8~24 h, and the drying temperature is 80℃. o C-120 o C.

[0026] Furthermore, in step S14, the secondary ball milling speed is 260~400 r / min, and the ball milling is carried out for 8~48 h.

[0027] Furthermore, in step S2, the solvent is a mixed solution of ethanol and ethyl acetate, the dispersant is tributyl phosphate, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyalkylene glycol and butyl benzyl phthalate.

[0028] Further, in step S2, the ball milling mixture is mixed for 2 h to 48 h to obtain a mixed slurry, which is then defoamed by vacuum defoaming for 3 to 20 min to obtain a casting slurry; after casting in a casting machine, it is dried at room temperature for 12 h to 24 h to obtain a casting film.

[0029] Furthermore, in step S31, the internal electrode slurry is Ag-Pd or Pt slurry.

[0030] Furthermore, in step S31, the number of green medium layers n>5.

[0031] Furthermore, in step S35, the terminal electrode paste is a silver electrode paste.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. The high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor disclosed in this invention significantly improves energy storage performance and allows for the control of the chemical composition of the ceramic material (Na). 0.75-x Bi 0.125 Li 0.125 Nb 0.75-xy-xz Ti 0.25 )-xBa(P y Q z In this model, x ranges from 0.01 to 0.06; y ranges from 0.01 to 0.02; and z ranges from 0.01 to 0.04. Combined with the fact that the average grain size of the energy storage ceramic capacitor is in the micrometer range and the average thickness of the dielectric layer is 8-15 μm, the capacitor can release a storage density (W / W). rec >15 J / cm 3 The energy storage efficiency (η) is greater than 85%.

[0034] 2. The high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor disclosed in this invention exhibits excellent energy storage performance and temperature stability. In its material composition, P is one or a combination of Mg, Ni, Ta, and Sb, and Q is one or a combination of Mn, Nb, and Zr. Combined with sodium niobate-based ferroelectric ceramic thick-film material powder and casting thick-film preparation processes, the capacitor achieves excellent temperature stability at 20°C. o C~200 oWithin the temperature range of C, the energy storage density W re The energy storage efficiency η changes with temperature at a rate of less than 8%; W is tested in the frequency range of 0.5 Hz to 240 Hz. rec With a change rate of less than 6% for η, it has significant advantages in energy storage performance.

[0035] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0037] Figure 1 The XRD pattern of the ferroelectric multilayer ceramic capacitor prepared in Example 1 of this invention;

[0038] Figure 2 These are scanning electron microscope (SEM) morphology comparisons of the ferroelectric multilayer ceramic capacitors prepared in Example 3 of this invention at their respective temperatures; wherein... Figure 2 (a) is a scanning electron microscope image taken by NanoStation. Figure 2 (b) is a scanning electron microscope image taken by SU8600;

[0039] Figure 3 This is a schematic diagram of the unipolar hysteresis loop of the ferroelectric multilayer ceramic capacitors prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0040] Figure 4 The dielectric temperature spectrum of the ferroelectric multilayer ceramic capacitor prepared in Example 1 of this invention at 1 kHz;

[0041] Figure 5 This is a graph showing the change of the unipolar hysteresis loop of the ferroelectric multilayer ceramic capacitor prepared in Example 2 of this invention with temperature. Detailed Implementation

[0042] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0043] In the following examples and comparative examples, anhydrous ethanol was used as the solvent.

[0044] Example 1

[0045] Provide a (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 The O3 multilayer ceramic capacitor is prepared by means of the following steps:

[0046] S1, Preparation (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 )O3 powder:

[0047] S11, according to the general chemical formula (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 The stoichiometric ratio of Na₂CO₃ powder, Nb₂O₅ powder, Bi₂O₃ powder, Li₂CO₃ powder, BaCO₃ powder, TiO₂ powder, and 5MgCO₃·Mg(OH)₂·5H₂O powder was used as raw materials. The weighed raw materials were placed in a nylon ball mill jar, with anhydrous ethanol as the solvent and zirconium balls as the grinding media; the mass ratio of raw material powder:zirconium balls:anhydrous ethanol was 1:2:1. The mixture was ball-milled at 360 r / min for 8 hours, and then removed and milled at 110 °C. o Dry at C for 8 hours.

[0048] Step S12: According to 5 oThe heating rate of C / min heated the mixed raw materials to 850 o C, and at 850 o Pre-calcination at temperature C for 6 h yielded sodium niobate-based ferroelectric ceramic pre-calcined powder.

[0049] Step S13: The obtained sodium niobate-based ferroelectric ceramic pre-sintered powder is subjected to secondary ball milling at 360 r / min for 12 h. After removal, it is then subjected to 110 o Drying at C for 8 hours yielded dried (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 )O3 powder.

[0050] S2, Preparation (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 O3 cast film

[0051] S21, (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 O3 powder, ethyl acetate-ethanol solvent and dispersant tributyl phosphate were ball-milled for 12 hours at a mass ratio of 1:0.8:0.02 to obtain a preliminary slurry. The ball milling speed was 220 r / min. The mass ratio of ethyl acetate to ethanol solvent in the ethyl acetate-ethanol solvent was 1:1.5.

[0052] S22. Add the binder polyvinyl butyral to the preliminary slurry obtained in step S21, wherein the mass ratio of powder: binder: plasticizer is 1:0.45:0.08, and the plasticizer is polyalkylene glycol and butyl benzyl phthalate. Then, ball mill at 220 r / min for 6 h to obtain the final slurry, wherein the mass ratio of polyalkylene glycol and butyl benzyl phthalate in the plasticizer is 1:0.8.

[0053] S23. The final slurry obtained in step S23 is defoamed using a vacuum defoaming method. The vacuum degree is set to 13 kPa, the rotation speed is 1800 r / min, and the time is 10 min. Then, it is cast using a casting machine at a casting speed of 1 m / min. After drying at room temperature, the thickness of the cast film is approximately 15 μm.

[0054] S3, Preparation (Na) 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 O3 multilayer ceramic capacitor.

[0055] S31. Use a cutting machine to cut the dried thick film obtained in step S23 into squares with sides of 15 cm x 15 cm; use a screen printing machine to print Ag-Pd internal electrodes on the cut film strips.

[0056] S32. Electrode-printed film strips are stacked together by hot pressing to obtain a multilayer film, with a total of five layers. Ten blank film strips are then stacked on top and below the multilayer film to prevent bending of the capacitor after sintering, resulting in a multilayer capacitor green body. The hot pressing temperature is 55°C. o C, pressure 10MPa, pressure holding time for each stack 5 minutes.

[0057] S33. Use a warm isostatic press to perform warm isostatic pressing on the multilayer capacitor green blank obtained in step S32. Vacuum seal the multilayer capacitor green blank to ensure that it will not leak water. Then place it in the water of the warm isostatic press at a pressure of 40MPa and hold the pressure for 10 minutes to obtain the warm isostatic pressed blank. Cut it into individual blanks.

[0058] S34, according to a heating rate of 0.5 o C / min, the warm isostatically pressed billet obtained in step S33 is heated to 500 o C, and in 500 o Insulate at temperature C for 4 hours, then remove adhesive.

[0059] S35. Place the debinding multilayer ceramic green body in a double-layer alumina sealed crucible, and use the sodium niobate-based ferroelectric ceramic powder obtained in step S13 to bury the multilayer ceramic green body, with a density of 2... o Heating rate increased to 1050 °C / min. o C, and at a temperature of 1050 o Sintering at temperature C for 2 hours yielded a multilayer ceramic block.

[0060] S36. After polishing the end electrode surface of the sintered multilayer ceramic block, apply end electrode slurry, and heat at a rate of 5... o Heating rate increased to 550 °C / min o C, and at 550 o Under C conditions, the end was burned for 30 min to obtain (Na) 0.71 Bi 0.125Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 O3 multilayer ceramic capacitor.

[0061] like Figure 1 The XRD pattern of the sodium niobate-based ferroelectric multilayer ceramic capacitor prepared in Example 1 is shown. As can be seen from the figure, the ceramic has a pure perovskite phase structure with no impurity phases present.

[0062] like Figure 4 The dielectric constant of the ferroelectric multilayer ceramic capacitor prepared in Example 1 is shown at 1 kHz. The figure shows that the maximum dielectric constant is obtained near room temperature, and the dielectric constant exhibits a slow decreasing trend with temperature. The dielectric constant curve is located at -55°C. o C~200 o The C-shaped structure exhibits a distinct plateau-like characteristic, indicating that multilayer ceramic capacitors possess excellent dielectric temperature stability, which is beneficial for achieving stable energy storage performance over a wide temperature range and expanding the application scope of multilayer ceramic capacitors.

[0063] Example 2

[0064] The difference between Example 2 and Example 1 is that the thickness of the cast thick film obtained in step S2 is 20 μm.

[0065] Reference Figure 5 The unipolar hysteresis loop diagrams of the ferroelectric multilayer ceramic capacitor prepared in Example 2 were obtained by testing at different temperatures. The diagrams show that the shape of the hysteresis loop does not change significantly with increasing temperature, and the residual polarization and maximum polarization on the loop remain stable at 20°C. o C~200 o Within the temperature range of C, the energy storage density and energy storage efficiency change with temperature at a rate of less than 8%. The results indicate that the sodium niobate-based multilayer ceramic capacitor exhibits good temperature stability in its energy storage performance.

[0066] Example 3

[0067] The difference between Example 3 and Example 1 is that the thickness of the cast thick film obtained in step S2 is 30 μm.

[0068] Reference Figure 2 The internal microstructure of the ferroelectric multilayer ceramic capacitor prepared in Example 3. Figure 2 (a) is a scanning electron microscope image taken by NanoStation, showing the internal cross-sectional morphology exposed after the energy storage ceramic material is sintered and fractured. The size, shape and dense packing of the ceramic grains can be clearly observed. Figure 2(b) is a scanning electron microscope image taken by SU8600, showing the surface morphology of the ceramic dielectric layer prepared by tape casting. The parallel lines in the image represent the internal Ag-Pd electrodes, reflecting the flatness and uniformity of the electrode layer during the casting process, and their tight bonding with the dielectric layer. In short, the left image reveals the internal microstructure of the material, while the right image shows the internal morphology characteristics of the material after sintering.

[0069] Depend on Figure 2 As can be seen, the ceramic is well-developed, with uniform grain size distribution, clear grain boundaries and no obvious pores. The average grain size is about 1.5 μm. The electrode layer is clear and continuous, and the thickness of a single dielectric layer is about 22 μm. The electrode layer and the dielectric layer are tightly connected with a clear interface. The uniform and dense microstructure helps to obtain a high breakdown field strength, thereby achieving higher energy storage performance.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is that in step S2:

[0072] (Na 0.71 Bi 0.125 Li 0.125 Nb 0.71 Ti 0.25 )-0.04Ba(Mg 1 / 3 Nb 2 / 3 The mass ratio of O3 powder, ethyl acetate-ethanol solvent and dispersant tributyl phosphate is 1:0.7:0.03, and the thickness of the cast thick film is 90μm.

[0073] Analysis of the four sodium niobate-based ferroelectric multilayer ceramic capacitors obtained above yielded the following results: Figures 1-5 As shown in Table 1. The thicknesses were obtained from SEM observations.

[0074] Table 1: Performance of Four Sodium Niobate-Based Ferroelectric Multilayer Ceramic Capacitors

[0075]

[0076] Reference Figure 3The figures show the unipolar hysteresis loops of the ferroelectric multilayer ceramic capacitors prepared in Examples 1-3 and Comparative Example 1. In Figure 1, 1 corresponds to the sodium niobate-based ferroelectric multilayer ceramic capacitor obtained in Example 1; Figure 2 corresponds to the sodium niobate-based ferroelectric multilayer ceramic capacitor obtained in Example 2; Figure 3 corresponds to the sodium niobate-based ferroelectric multilayer ceramic capacitor obtained in Example 3; and Figure 4 corresponds to the sodium niobate-based ferroelectric multilayer ceramic capacitor obtained in Comparative Example 1. All components exhibit thin hysteresis loops. Compared to Comparative Example 1, Examples 1-3 show higher breakdown field strength and greater energy storage density, indicating that reducing the dielectric layer thickness of the multilayer ceramic capacitor helps to increase the breakdown field strength and achieve a greater energy storage density.

[0077] In summary, the ceramic material of this invention exhibits stable energy storage performance over a wide temperature range, and the multilayer ceramic capacitor element manufactured from this ceramic material can be applied to fields requiring a wide practical temperature range, such as power and pulse applications.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor, characterized in that, The general chemical formula of the energy storage ceramic capacitor is (Na) 0.75-x Bi 0.125 Li 0.125 Nb 0.75-xy-xz Ti 0.25 )-xBa(P y Q z O3, where x takes values ​​in the range of 0.01≤x≤0.06; y takes values ​​in the range of 0.01≤y≤0.02; z takes values ​​in the range of 0.01≤z≤0.04; P is one or a combination of Mg, Ni, Ta and Sb; and Q is one or a combination of Mn, Nb and Zr.

2. The energy storage ceramic capacitor as described in claim 1, characterized in that, The energy storage ceramic capacitor has an average grain size in the micrometer range, a relative density higher than 97%, and an average dielectric layer thickness of 8-15 μm, which can release energy density (W). rec >15J / cm 3 The energy storage efficiency (η) is greater than 85%; in 20 o C~140 o C Test temperature range W rec The rate of change of η is less than 8%; W is tested in the frequency range of 0.5 Hz to 240 Hz. rec The rate of change of η is less than 6%.

3. The method for preparing a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor as described in claim 2, characterized in that, Includes the following steps: S1. Preparation of sodium niobate-based ferroelectric ceramic thick film material powder; S2. Prepare a cast thick film based on the powder prepared in step S1; S3. Combine the cast thick film prepared in step S2 with the powder prepared in step S1 to prepare a multilayer energy storage ceramic capacitor.

4. The method for preparing the energy storage ceramic capacitor as described in claim 3, characterized in that, Step S1 specifically includes the following steps: S11, according to the general chemical formula (Na) 0.75-x Bi 0.125 Li 0.125 Nb 0.75-xy-xz Ti 0.25 )-xBa(P y Q z The stoichiometric ratio of O3 is determined by weighing Na2CO3 powder, Nb2O5 powder, Bi2O3 powder, Li2CO3 powder, BaCO3 powder, TiO2 powder, P oxide powder, and Q oxide powder as raw materials. The P oxide powder is one or a combination of several of 5MgCO3·Mg(OH)2·5H2O, NiO, Ta2O5, and Sb2O5, and the Q oxide powder is one or a combination of several of MnO2, Nb2O5, and ZrO2. The purity of all raw materials is ≥99%. S12. Using anhydrous ethanol as solvent and zirconium balls as grinding media, the weighed raw material powders Na2CO3 powder, Nb2O5 powder, Bi2O3 powder, Li2CO3 powder, BaCO3 powder, TiO2 powder, P oxide powder and Q oxide powder from step S11 are ball-milled and mixed, and then dried to obtain mixed raw materials. S13, according to 3 o C / min ~10 o The heating rate was increased to 750 °C / min to heat the mixed raw material obtained from drying in step S12. o C~900 o C, and at 750 o C~900 o Pre-calcination at temperature C for 3-7 h yields sodium niobate-based ferroelectric ceramic pre-calcined powder. S14. The sodium niobate-based ferroelectric ceramic pre-sintered powder obtained in step S13 is subjected to secondary ball milling and dried to obtain sodium niobate-based ferroelectric ceramic powder; the sodium niobate-based ferroelectric ceramic powder is a pure perovskite phase and the particle size is in the submicron range.

5. The method for preparing the energy storage ceramic capacitor as described in claim 4, characterized in that, Step S2 specifically involves: ball milling and mixing the sodium niobate-based ferroelectric ceramic powder, solvent, dispersant, binder, and plasticizer obtained in step S14; vacuum degassing the uniformly mixed slurry to obtain a casting slurry; casting the casting slurry on a casting machine at a speed of 0.5~1.5 m / min; and drying to obtain a casting film with a thickness of 8-50 μm.

6. The method for preparing the energy storage ceramic capacitor as described in claim 5, characterized in that, Step S3 specifically includes the following steps: S31. Cut the cast film obtained in step S2 into films, use the films according to the designed thickness of the dielectric layer, print the internal electrode paste on the surface of the dielectric layer, and hot press at a temperature of 20°C. o C~70 o Under conditions of C and pressure of 5 MPa to 50 MPa, the medium layer is hot-pressed and cross-laminated, and then blank films are stacked on the upper and lower surfaces of the stacked medium layer as protective layers to obtain the green blank. S32, when the hot water temperature is 20 o C~70 o Under conditions of C and pressure of 5 MPa to 50 MPa, the green blank obtained in step S31 is warm isostatically pressed for 3-60 min to obtain the warm isostatically pressed green blank. S33, according to a heating rate of 0.1 o C / min~3 o C / min, the warm isostatic pressing embryo from step S32 is heated to 400 o C-700 o C, and in 400 o C-700 o Insulate at C temperature and remove adhesive for 1-20 hours; S34. Place the multi-layer ceramic green body after debinding in step S33 into a double-layer alumina sealed crucible, and use the sodium niobate-based ferroelectric ceramic powder obtained in step S14 to bury the multi-layer ceramic green body, with a density of 2... o C / min ~10 o Heating rate increased to 1000 °C / min o C-1300 o C, and at a temperature of 1000 o C-1300 o Sintering at temperature C for 2-6 hours yields multilayer ceramic blocks. S35. After polishing the end electrode surface of the multilayer ceramic block obtained by sintering in step S34, apply end electrode slurry, and heat at a rate of 2... o C / min ~10 o Heating rate increased to 400 °C / min o C-600 o C, and in 400 o C-600 o Under temperature conditions of C, the end is sintered for 15-60 minutes to obtain a high-energy-storage sodium niobate-based temperature-stable ferroelectric multilayer ceramic capacitor.

7. The method for preparing the energy storage ceramic capacitor as described in claim 4, characterized in that, In step S12, the mass ratio of raw material powder:zirconium balls: anhydrous ethanol is 1:2:1; the ball milling speed is 260~400 r / min, the ball milling time is 8~24 h, and the drying temperature is 80℃. o C-120 o C; In step S14, the secondary ball milling speed is 260~400 r / min, and the ball milling is carried out for 8~48 h.

8. The method for preparing the energy storage ceramic capacitor as described in claim 5, characterized in that, In step S2, the solvent is a mixed solution of ethanol and ethyl acetate, the dispersant is tributyl phosphate, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyalkylene glycol and butyl benzyl phthalate.

9. The method for preparing the energy storage ceramic capacitor as described in claim 8, characterized in that, In step S2, ball milling is used to mix the materials for 2 h to 48 h to obtain a mixed slurry. The slurry is then defoamed by vacuum defoaming for 3 to 20 min to obtain a casting slurry. After casting in a casting machine, the slurry is dried at room temperature for 12 h to 24 h to obtain a casting film.

10. The method for preparing the energy storage ceramic capacitor as described in claim 6, characterized in that, In step S31, the inner electrode paste is Ag-Pd or Pt paste; in step S31, the number of green dielectric layers n>5; in step S35, the end electrode paste is silver electrode paste.

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