Sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance and preparation method thereof

Abstract

The present invention discloses a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, the general chemical formula of which is (1-x)(Bi 0.5 Na 0.5 Ti03‑BaTiO3)‑xNaTaO3, x is 0.03 to 0.10; a method for preparing a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention, comprising the steps of weighing raw materials in a stoichiometric ratio according to a general chemical composition formula, sequentially performing a first ball milling, a first drying, a pre-sintering, a second ball milling, a second drying, a screening, a tabletting, a cold isostatic pressing, and a sintering process to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance. The sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention and a preparation method thereof introduce a third component, NaTaO3, into the matrix to improve the density of the ceramic, increase the breakdown electric field, achieve excellent energy storage performance, and adopt cold isostatic pressing technology to save costs; the green body has high and uniform density, low stress in the green body, and is environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium bismuth titanate-based ceramic materials, and specifically relates to a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, and also relates to a preparation method of the above-mentioned sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance. Background Art

[0002] At present, there are two main bottlenecks in the development of lead-free ceramic energy storage capacitors: 1. High energy storage density W rec It is difficult to obtain both high energy storage efficiency and high energy storage efficiency η in the same ceramic energy storage capacitor; 2. High W rec It often needs to be obtained under very high electric field strength, which limits the practical application of ceramic energy storage capacitors.

[0003] Q.Li et al. (Tailoring antiferroelectricity with high energy-storageproperties in Bi 0.5 Na 0.5 TiO3-BaTiO3 ceramics by modulating Bi / Na ratio, J.Mater.Sci, Mater.Electron, 2016, 27) studied that by adjusting the Bi / Na ratio, the energy storage performance of BNTx-BT ceramics can be improved. The antiferroelectric with high energy storage performance in BNTx-BT ceramics can be achieved by adjusting the Bi / Na ratio. 0.94Bi 0.5+x Na 0.5-x TiO3-0.06BaTiO3 (BNTx-BT), BNTx-BT ceramics with x = 0.05 have a high energy storage density W = 1.76 J / cm under an electric field of 70 kV / cm due to their fine antiferroelectric double hysteresis. 3 However, in actual tests, the electric field breakdown field of 70 kV / cm is too small. The low breakdown electric field makes it difficult to improve the effective energy storage density of ceramic materials, and the stability of energy storage performance at different test frequencies and in different cycle tests needs to be explored. Summary of the Invention

[0004] The purpose of the present invention is to provide a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, which has the characteristics of high energy storage density and stable energy storage performance.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, which has the characteristics of simple process, good repeatability and low cost.

[0006] The technical solution adopted by the present invention is that the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance has a chemical composition formula of (1-x)(Bi 0.5 Na 0.5 Ti03-BaTiO3)-xNaTaO3, where x is 0.03 to 0.10.

[0007] The present invention is also characterized in that:

[0008] x is 0.08.

[0009] Another technical solution adopted by the present invention is a method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, the specific steps are as follows: according to the chemical composition formula (1-x)(Bi 0.5 Na 0.5 Ti03-BaTi O3)-xNaTaO3, x is 0.03-0.10, and the following raw materials are weighed respectively: Bi2O3 powder, Na2CO3 powder, BaCO3 powder, TiO2 powder and Ta2O5 powder. After mixing the weighed raw materials, they are subjected to primary ball milling, primary drying, pre-calcination, secondary ball milling, secondary drying, sieving, tableting, cold isostatic pressing and sintering in sequence to obtain sodium bismuth titanate-based lead-free ceramic materials with excellent energy storage performance.

[0010] Another technical solution of the present invention is also characterized in that:

[0011] The purity of each raw material is ≥99.00%.

[0012] The time for the first ball milling and the second ball milling is 20h-28h, and the ball milling medium is anhydrous ethanol; the conditions for the first drying and the second drying are both: drying at 60℃-100℃ for 20h-28h.

[0013] The pre-firing conditions are: heating to 800°C to 900°C at a heating rate of 3°C / min and pre-firing for 2h to 4h.

[0014] The pre-sintering conditions are: heating to 850°C at a heating rate of 3°C / min and pre-sintering for 3h.

[0015] The sieving is performed by using a 120-300 mesh sieve to obtain the pre-burned powder.

[0016] The tablet is pressed into a cylindrical green body using a powder tablet press; the cold isostatic pressing condition is: cold isostatic pressing at a pressure of 200MPa to 240MPa for 4 to 8 minutes; the sintering condition is: heating to 1100°C to 1200°C at a heating rate of 3°C / min and sintering for 2 to 4 hours.

[0017] The cold isostatic pressing conditions are: cold isostatic pressing at a pressure of 200 MPa for 6 minutes; the sintering conditions are heating to 1150°C at a heating rate of 3°C / min and sintering for 3 hours.

[0018] The beneficial effects of the present invention are:

[0019] 1) The sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention is 0.5 Na 0.5 The third component NaTaO3, Ta 5+ The introduction of inhibits grain growth, reduces its residual polarization strength, increases its breakdown electric field by improving the density of the ceramic, helps to obtain a slender hysteresis loop, and has excellent energy storage performance;

[0020] 2) The preparation method of sodium bismuth titanate-based lead-free ceramic materials with excellent energy storage performance of the present invention adopts cold isostatic pressing technology, which avoids sample waste, eliminates the binder and subsequent debinding process, saves costs, and shortens the preparation cycle; at the same time, the green body formed by cold isostatic pressing has high density, uniform density, and low stress in the green body, which reduces the occurrence of green body cracking, delamination, etc., improves the quality of ceramics, and the selected raw materials do not contain lead heavy metals and are environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The XRD patterns of Examples 1 to 4 of the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention are shown;

[0022] Figure 2 Graphs showing the dielectric constant and dielectric loss of Example 1 of the present invention at different test frequencies;

[0023] Figure 3 Graphs showing dielectric constant and dielectric loss at different test frequencies for Example 3 of the present invention;

[0024] Figure 4 1 is a diagram of unipolar hysteresis loops of Examples 1 to 4 of the present invention;

[0025] Figure 5 is a graph showing changes in saturation polarization intensity, remanent polarization intensity, and polarization intensity difference of Examples 1 to 4 of the present invention;

[0026] Figure 6 Graph showing changes in energy storage density and energy storage efficiency for Examples 1 to 4 of the present invention;

[0027] Figure 7 This is a graph showing changes in the hysteresis loop at different frequencies according to Example 3 of the present invention;

[0028] Figure 8This is a performance change diagram at corresponding frequencies of Example 3 of the present invention;

[0029] Figure 9 This is a graph showing changes in the hysteresis loop under different cycle times in Example 3 of the present invention;

[0030] Figure 10 3 is a performance change diagram under corresponding cycle numbers of Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention has a general chemical composition formula of (1-x)(Bi 0.5 Na 0.5 Ti03-BaTiO3)-xNaTaO3, where x is between 0.03 and 0.10; the grain size in this value range gradually decreases, and with the increase of tantalum content, the effective energy storage density first increases and then decreases. When the value is outside this range, the effective energy storage density gradually decreases.

[0033] When x is 0.08, the chemical formula is 0.92(Bi 0.5 Na 0.5 TiO3-BaTiO3)-0.08NaTaO3, effective energy storage density is 3.01~3.15J / cm 3 , the total energy storage density is 4.41~4.61J / cm 3 , the energy storage efficiency is 68-70%.

[0034] Increased the number of loops from 1 to 10 5 When the test frequency increases from 5Hz to 200Hz, the change rate of the effective energy storage density of the ceramic is less than 4.6~4.8%, and the change rate of the energy storage efficiency is less than 3.7~3.9%. When the number of cycles increases from 1 to 10 5 When the effective energy storage density is less than 5-7%, the change rate of the energy storage efficiency is less than 1.3-1.5%.

[0035] The sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention is 0.5 Na 0.5 The third component NaTaO3, Ta 5+The introduction of inhibits grain growth, reduces its residual polarization strength, increases its breakdown electric field by improving the density of the ceramic, helps to obtain a slender hysteresis loop, has high energy storage density and excellent energy storage performance stability, and can meet the application needs of capacitors with high energy storage density and stable energy storage performance.

[0036] The preparation method of the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention comprises the following steps:

[0037] Step 1: According to (1-x)(Bi 0.5 Na 0.5 The stoichiometric ratio of TiO3-BaTiO3)-xNaTaO3 is 0.03-0.10, and the following raw materials are weighed separately: Bi2O3 powder, Na2CO3 powder, BaCO3 powder, TiO2 powder, and Ta2O5 powder, each of which has a purity of more than 99.00%. All the weighed raw materials are mixed uniformly and then placed in a nylon jar for a single ball milling, using zirconium balls as milling balls and anhydrous ethanol as the ball milling medium. The mixture is thoroughly mixed and ball milled for 20 to 28 hours, and then dried at 60°C to 100°C for 20 to 28 hours to obtain a raw material mixture.

[0038] Step 2: placing the raw material mixture in an alumina crucible, compacting it with an agate rod, covering it, placing it in a resistance furnace, heating it to 800° C. to 900° C. at a heating rate of 3° C. / min, pre-calcining it for 2 h to 4 h, placing it in a nylon jar and performing secondary ball milling, using zirconium balls as grinding balls and anhydrous ethanol as ball milling medium, ball milling for 20 h to 28 h, drying it at 60° C. to 100° C. for 20 h to 28 h, and sieving it with a 120-300 mesh sieve to obtain a pre-calcined powder;

[0039] The pre-calcination is preferably carried out by heating the temperature to 850° C. at a heating rate of 3° C. / min for 3 h.

[0040] Step 3: After the pre-burned powder is pressed into a cylindrical green body using a powder tablet press, it is cold isostatically pressed at a pressure of 200 MPa to 240 MPa for 4 to 8 minutes, and sintered at 1100° C. to 1200° C. for 2 to 4 hours to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance.

[0041] In step 3, cold isostatic pressing is preferably performed at a pressure of 200 MPa for 6 minutes.

[0042] In step 3, sintering is preferably performed at 1150° C. for 3 hours.

[0043] The preparation method of the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention adopts advanced cold isostatic pressing technology, which avoids sample waste, saves the cost of adhesives and subsequent debinding processes, and shortens the preparation cycle of ceramics; at the same time, the green body formed by cold isostatic pressing has high density, uniform density, and low stress in the green body, which reduces defects such as green body cracking and delamination, which provides a guarantee for the quality of the ceramics, and the selected raw materials do not contain lead heavy metals and are environmentally friendly.

[0044] Example 1

[0045] 1. Ingredients

[0046] According to (1-x)(Bi 0.5 Na 0.5 0.03 in the stoichiometric ratio of TiO3-BaTiO3-xNaTaO3, 9.1316 g of 99% pure Bi2O3 powder, 2.2912 g of 99.8% pure Na2CO3 powder, 0.9875 g of 99% pure BaCO3 powder, 6.6296 g of 99.5% pure TiO2 powder, and 0.9601 g of 99.99% pure Ta2O5 powder were weighed, mixed evenly, and then put into a nylon jar for a single ball milling, using zirconium balls as grinding balls and anhydrous ethanol as ball milling medium, and fully mixed and ball milled for 24 hours. The zirconium balls were separated, dried at 80°C for 24 hours, and ground in a mortar to obtain a raw material mixture;

[0047] 2. The raw material mixture was placed in an alumina crucible, compacted with an agate rod, covered, and placed in a resistance furnace. The temperature was increased to 850°C at a heating rate of 3°C / min, pre-calcined for 3 hours, and naturally cooled to room temperature with the furnace. After grinding with a mortar for 30 minutes, the mixture was placed in a nylon jar and subjected to secondary ball milling. Zirconium balls were used as grinding balls and anhydrous ethanol was used as the ball milling medium. The ball milling was carried out for 24 hours. The zirconium balls were separated and dried in a drying oven at 80°C for 24 hours. The mixture was further ground with a mortar for 10 minutes and sieved with a 180-mesh sieve to obtain a pre-calcined powder.

[0048] 3. The pre-sintered powder was placed in a stainless steel mold with a diameter of 11.5 mm, and pressed into a cylindrical body with a thickness of 1.5 mm using a powder tablet press without pressure. The cylindrical body was placed in a cold isostatic press and cold isostatically pressed at a pressure of 200 MPa for 6 minutes. The cylindrical body was placed on a zirconia plate, which was placed in an alumina sealed sagger. The temperature was raised to 1150°C at a heating rate of 3°C / min, sintered for 3 hours, and naturally cooled to room temperature with the furnace to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance. The general chemical composition formula is: 0.97(Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.03NaTaO3.

[0049] Example 2

[0050] According to (1-x)(Bi 0.5 Na 0.5 TiO3-BaTiO3)-xNaTaO3 (x=0.05 in the stoichiometric ratio), weigh 8.7902g of 99% pure Bi2O3 powder, 2.3504g of 99.8% pure Na2CO3 powder, 0.9505g of 99% pure BaCO3 powder, 6.3818g of 99.5% pure TiO2 powder, and 1.5270g of 99.99% pure Ta2O5 powder;

[0051] The other steps are the same as those in Example 1, and a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance is obtained. The general chemical composition formula is: 0.95 (Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.05NaTaO3.

[0052] Example 3

[0053] According to (1-x)(Bi 0.5 Na 0.5 TiO3-BaTiO3)-xNaTaO3 (x=0.08 in the stoichiometric ratio), 8.5649 g of 99% pure Bi2O3 powder, 2.3895 g of 99.8% pure Na2CO3 powder, 0.9262 g of 99% pure BaCO3 powder, 6.2182 g of 99.5% pure TiO2 powder, and 1.9012 g of 99.99% pure Ta2O5 powder were weighed respectively;

[0054] The other steps are the same as those in Example 1, and a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance is obtained. The general chemical composition formula is: 0.92 (Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.08NaTaO3.

[0055] Example 4

[0056] According to (1-x)(Bi 0.5 Na 0.5TiO3-BaTiO3)-xNaTaO3 (x=0.10 in the stoichiometric ratio), weigh 8.3414 g of 99% pure Bi2O3 powder, 2.4283 g of 99.8% pure Na2CO3 powder, 0.9020 g of 99% pure BaCO3 powder, 6.0559 g of 99.5% pure TiO2 powder, and 2.2724 g of 99.99% pure Ta2O5 powder;

[0057] The other steps are the same as those in Example 1, and a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance is obtained. The general chemical composition formula is: 0.90 (Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.10NaTaO3.

[0058] Example 5

[0059] 1. Ingredients

[0060] According to (1-x)(Bi 0.5 Na 0.5 8.5649 g of 99% pure Bi2O3 powder, 2.3895 g of 99.8% pure Na2CO3 powder, 0.9262 g of 99% pure BaCO3 powder, 6.2182 g of 99.5% pure TiO2 powder, and 1.9012 g of 99.99% pure Ta2O5 powder were weighed respectively; after uniformly mixing, the mixture was placed in a nylon jar and ball-milled once using zirconium balls as grinding balls and anhydrous ethanol as ball-milling medium, and the mixture was thoroughly mixed and ball-milled for 28 hours. The zirconium balls were separated, dried at 60° C. for 28 hours, and ground in a mortar to obtain a raw material mixture;

[0061] 2. The raw material mixture was placed in an alumina crucible, compacted with an agate rod, covered, and placed in a resistance furnace. The temperature was raised to 900°C at a heating rate of 3°C / min, pre-fired for 2 hours, and naturally cooled to room temperature with the furnace. After grinding with a mortar for 30 minutes, the mixture was placed in a nylon jar and subjected to secondary ball milling. Zirconium balls were used as grinding balls and anhydrous ethanol was used as the ball milling medium. The ball milling was carried out for 28 hours. The zirconium balls were separated and dried in a drying oven at 60°C for 28 hours. The mixture was further ground with a mortar for 10 minutes and sieved with a 120-mesh sieve to obtain a pre-fired powder.

[0062] 3. The pre-sintered powder was placed in a stainless steel mold with a diameter of 11.5 mm, and pressed into a cylindrical body with a thickness of 1.5 mm using a powder tablet press without pressure. The cylindrical body was placed in a cold isostatic press and cold isostatically pressed at a pressure of 220 MPa for 8 minutes. The cylindrical body was placed on a zirconia plate, which was placed in an alumina sealed sagger. The temperature was raised to 1100°C at a heating rate of 3°C / min, sintered for 4 hours, and naturally cooled to room temperature with the furnace to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance. The general chemical formula is: 0.92(Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.08NaTaO3.

[0063] Example 6

[0064] 1. Ingredients

[0065] According to (1-x)(Bi 0.5 Na 0.5 8.5649 g of 99% pure Bi2O3 powder, 2.3895 g of 99.8% pure Na2CO3 powder, 0.9262 g of 99% pure BaCO3 powder, 6.2182 g of 99.5% pure TiO2 powder, and 1.9012 g of 99.99% pure Ta2O5 powder were weighed respectively; after uniformly mixing, the mixture was placed in a nylon jar and ball-milled once using zirconium balls as grinding balls and anhydrous ethanol as ball-milling medium, and the mixture was thoroughly mixed and ball-milled for 20 hours. The zirconium balls were separated, and the mixture was dried at 100° C. for 20 hours, and ground in a mortar to obtain a raw material mixture;

[0066] 2. The raw material mixture was placed in an alumina crucible, compacted with an agate rod, covered, and placed in a resistance furnace. The temperature was increased to 800°C at a heating rate of 3°C / min, pre-fired for 4 hours, and naturally cooled to room temperature with the furnace. After grinding with a mortar for 30 minutes, the mixture was placed in a nylon jar and subjected to secondary ball milling. Zirconium balls were used as grinding balls and anhydrous ethanol was used as the ball milling medium. The ball milling was carried out for 20 hours. The zirconium balls were separated and dried in a drying oven at 100°C for 20 hours. The mixture was further ground with a mortar for 10 minutes and sieved with a 300-mesh sieve to obtain a pre-fired powder.

[0067] 3. The pre-sintered powder was placed in a stainless steel mold with a diameter of 11.5 mm, and pressed into a cylindrical body with a thickness of 1.5 mm using a powder tablet press without pressure. The cylindrical body was placed in a cold isostatic press and cold isostatically pressed at a pressure of 240 MPa for 4 minutes. The cylindrical body was placed on a zirconia plate, which was placed in an alumina sealed sagger. The temperature was raised to 1200°C at a heating rate of 3°C / min, sintered for 2 hours, and naturally cooled to room temperature with the furnace to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance. The general chemical composition formula is: 0.92(Bi 0.5 Na 0.5 Ti03-BaTiO3)-0.08NaTaO3.

[0068] The surface of the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance prepared in Examples 1 to 4 was ground, polished, ultrasonically cleaned, and wiped clean. Silver paste was applied to the upper and lower surfaces respectively, and the material was placed in a muffle furnace at 840°C for 30 minutes and naturally cooled to room temperature. The structure and performance of the ceramic material were characterized using a SmartLab9 X-ray diffractometer produced by Rigaku Corporation of Japan, a 4294A and E4980A dielectric analyzer produced by Agilent Technologies Co., Ltd., and a ferroelectric tester produced by Radiant Corporation of the United States. The results are as follows: Figures 1 to 10 shown.

[0069] Figure 1 The XRD patterns of Examples 1 to 4 show that the strongest single diffraction peak exists at a 2θ angle of about 32°. Compared with the BNT standard PDF card (PDF#97-004-3769), it can be seen that the phase structure of these four groups of (1-x)(BNT-BT)-xNT ceramic samples is a pure rhombohedral perovskite structure without any impurity phase. This shows that NT has been completely dissolved into the main lattice of BNT-BT. Figure 2 This is a diagram of dielectric constant and dielectric loss at different test frequencies in Example 1. Figure 3 : is a graph of dielectric constant and dielectric loss of the ceramic material prepared in Example 3 at different test frequencies, Figure 2 and Figure 3 The test temperature range is from -150℃ to 500℃. It can be seen that with the increase of doping content, the dielectric constant gradually decreases and the corresponding Curie temperature gradually decreases. This is because NT has a lower T m value, and the dielectric peak gradually broadens, proving that with the incorporation of NT, the temperature stability range of the dielectric constant is widened, indicating that the dielectric constant of the ceramic has good temperature stability.

[0070] Figure 41 is a diagram of the unipolar hysteresis loop of the ceramic material prepared in Examples 1 to 4. It can be seen from the diagram that with the increase of the doping amount of the third component NaTaO3, the hysteresis loop gradually becomes slender, which is conducive to obtaining better energy storage efficiency. Figure 5 This is a graph showing the changes in polarization intensity and polarization intensity difference of the ceramic materials prepared in Examples 1 to 4. As the doping amount of the third element NaTaO3 increases, the maximum polarization intensity of the ceramic material is improved, the residual polarization intensity decreases, and the polarization intensity difference gradually increases. The maximum polarization intensity difference is achieved when x = 0.08.

[0071] Figure 6 The graphs of the effective energy storage density, total energy storage density, and energy storage efficiency of the ceramic materials prepared in Examples 1 to 4 show that the comprehensive energy storage performance of the ceramic materials is good. When x = 0.08, the effective energy storage density can reach 3.07 J / cm 3 , the total energy storage density can reach 4.51J / cm 3 , the energy storage efficiency is 68%.

[0072] Figure 7 This is a graph showing the change of the unipolar hysteresis loop of the ceramic prepared in Example 3 as the test frequency increases from 5 Hz to 200 Hz. It can be observed from the graph that the hysteresis loop has almost no change. Figure 8 It is a change diagram of effective energy storage density, total energy storage density and energy storage efficiency under corresponding frequency. When the test frequency increases from 5Hz to 200Hz, the change rate of effective energy storage density is less than 4.7%, and the change rate of energy storage efficiency is less than 3.8%.

[0073] Figure 9 The prepared in Example 3 increases with the number of cycles from 1 to 10. 5 The unipolar hysteresis loop of . As can be seen from the figure, the change of the hysteresis loop is very small. Figure 10 It is a graph showing the changes in effective energy storage density, total energy storage density, and energy storage efficiency under the corresponding number of cycles. When the number of cycles increases from 1 to 10 5 When the temperature is 0.0400 V, the change rate of effective energy storage density is less than 6%, and the change rate of energy storage efficiency is less than 1.4%.

[0074] The sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance of the present invention has both excellent energy storage density and good energy storage performance stability under different cycle numbers and different test frequencies, and can broaden the application range of electronic functional materials.

Claims

1. Sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, characterized in that: The general chemical formula is (1-x)(Bi 0.5 Na 0.5 TiO3-BaTiO3)-xNaTaO3, where x is 0.08, and the effective energy storage density is 3.01-3.15 J / cm 3 , the total energy storage density is 4.41~4.61J / cm 3 , the energy storage efficiency is 68-70%.

2. A method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance, characterized in that: The specific steps are as follows: 0.5 Na 0.5 TiO3-BaTiO3)-xNaTaO3, where x is 0.08, the following raw materials are weighed respectively: Bi2O3 powder, Na2CO3 powder, BaCO3 powder, TiO2 powder and Ta2O5 powder, the weighed raw materials are mixed, and then subjected to primary ball milling, primary drying, pre-calcination, secondary ball milling, secondary drying, sieving, tableting, cold isostatic pressing and sintering in sequence to obtain a sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance; The tablet is pressed into a cylindrical green body using a powder tablet press; the cold isostatic pressing condition is: cold isostatic pressing for 4 to 8 minutes at a pressure of 200 MPa to 240 MPa; the sintering condition is heating to 1100 to 1200° C. at a heating rate of 3° C. / min and sintering for 2 to 4 hours.

3. The method for preparing the sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 2, characterized in that: The purity of each raw material is ≥99.00%.

4. The method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 2, characterized in that: The time for the first ball milling and the second ball milling is 20 hours to 28 hours, and the ball milling medium is anhydrous ethanol; the conditions for the first drying and the second drying are both: drying at 60° C. to 100° C. for 20 hours to 28 hours.

5. The method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 2, characterized in that: The pre-calcination conditions are: heating to 800° C. to 900° C. at a heating rate of 3° C. / min and pre-calcining for 2 h to 4 h.

6. The method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 5, characterized in that: The pre-firing conditions are: heating to 850° C. at a heating rate of 3° C. / min and pre-firing for 3 hours.

7. The method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 2, characterized in that: The sieving is performed by using a 120-300 mesh sieve to obtain the pre-burned powder.

8. The method for preparing sodium bismuth titanate-based lead-free ceramic material with excellent energy storage performance according to claim 2, characterized in that: The cold isostatic pressing condition is: cold isostatic pressing for 6 minutes at a pressure of 200 MPa; the sintering condition is heating to 1150° C. at a heating rate of 3° C. / min and sintering for 3 hours.

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