Bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, preparation method and application thereof

Abstract

The present invention relates to a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, a preparation method thereof and an application thereof. The relaxor ferroelectric ceramic material has the general formula Bi 3‑x La x TiNbO9, 0≤x≤1.1; this relaxor ferroelectric ceramic material is prepared by lanthanum-doping Bi3TiNbO9 using a solid-phase sintering method; the lanthanum doping is performed with lanthanum oxide. The present invention has the advantage that the resulting bismuth titanate niobate-based relaxor ferroelectric energy storage ceramic material effectively overcomes the low energy storage density and efficiency of conventional ferroelectric materials, especially bismuth layered ferroelectric materials, making the energy storage performance of the present invention significantly superior to that of undoped bismuth titanate niobate ferroelectric ceramics and other bismuth layered ferroelectric ceramic materials, while also having better working environment stability. The preparation method of the present invention is simple, the raw materials are readily available, and the production efficiency is high, making it suitable for large-scale practical production applications.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric energy storage ceramic materials, and in particular to a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, and a preparation method and application thereof. Background Art

[0002] Dielectric energy storage ceramic capacitors, with their high power density, fast charge / discharge speeds, and excellent reliability, are ubiquitous components in current electronic devices and power systems, and are widely and crucially used in high-power / pulse power systems. However, current dielectric ceramic capacitors generally have low energy storage density, making them difficult to adapt to the current trend toward miniaturized and integrated devices. Therefore, the development of high-performance dielectric capacitors is crucial, both for promoting national economic development and for breaking through technological bottlenecks in key areas and equipment.

[0003] Due to the harmful effects of lead on the environment and human body, lead-free dielectric energy storage materials are currently a research hotspot. Bismuth layered compounds are a kind of Aurivillius phase layered perovskite material, which is composed of Bi2O2 layer and perovskite-like structure A n-1 B n O 3n+1 The perovskite-like structure of the Bi2O2 layer, which is formed by alternating layers, effectively suppresses the long-range diffusion of space charge and defects caused by domain wall motion, forming an electrode-ferroelectric interface and thus achieving excellent fatigue resistance. In addition, the Bi2O2 layer itself has high insulating properties, which gives the bismuth layered compound a high breakdown electric field. These excellent properties make bismuth layered compounds a potential high-performance dielectric energy storage material. Bismuth titanate niobate ferroelectrics are a typical type of bismuth layered ferroelectric with a high Curie temperature and high spontaneous polarization. However, they suffer from high remanent polarization and low breakdown electric field, which restrict their application prospects in the field of energy storage. In addition, after extensive literature research on bismuth titanate niobate-based ferroelectric ceramics, it was found that the hysteresis loop (PE curve) directly related to energy storage density is rarely reported. Therefore, improving the energy storage density and energy storage efficiency of bismuth titanate niobate-based ferroelectric ceramics through various research methods has important production practical significance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, a preparation method and application thereof. By introducing lanthanum elements to modify Bi3TiNbO9 ferroelectric ceramics, the prepared bismuth titanate niobate-based relaxor ferroelectric energy storage ceramic can effectively overcome the shortcomings of high remnant polarization and low breakdown electric field. The energy storage performance is significantly better than that of undoped bismuth titanate niobate ferroelectric ceramics and other bismuth layered ferroelectric ceramic materials, and at the same time has good working environment stability.

[0005] The present invention is achieved through the following technical solutions: On the one hand, a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage is provided, the general formula of which is Bi 3-x La x TiNbO9, 0≤x≤1.1.

[0006] Through the above technical solution, the bismuth titanate niobate-based relaxor ferroelectric energy storage ceramic of the present invention can effectively overcome the shortcomings of high remnant polarization and low breakdown electric field, and its energy storage performance is significantly better than that of undoped bismuth titanate niobate ferroelectric ceramics and other bismuth layered ferroelectric ceramic materials, while also having good working environment stability.

[0007] Furthermore, the relaxor ferroelectric ceramic material is prepared by lanthanum-doped Bi3TiNbO9 based on a solid-phase sintering method; the lanthanum doping is added using oxide as a raw material.

[0008] Furthermore, the relaxor ferroelectric ceramic material Bi 3-x La x The molar ratio of each raw material in TiNbO9 is Bi2O3:La2O3:TiO2:Nb2O5, and the molar ratio is 1.9-3:0-1.1:2:1.

[0009] In addition, a method for preparing the above-mentioned bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage is provided, comprising the following steps:

[0010] Step S1: preparing lanthanum-doped Bi3TiNbO9 bismuth titanate niobate-based relaxor ferroelectric ceramic powder by ball milling;

[0011] The raw materials were respectively prepared according to the general formula Bi 3-x La x TiNbO9, 0≤x≤1.1 is weighed and prepared, placed in a ball mill, and ball milled with zirconium oxide balls using anhydrous ethanol as a dispersion medium for 10-15 hours at a ball mill speed of 350-400 rpm. The ball-milled slurry is placed in a drying oven at 70°C to obtain a dry powder;

[0012] Step S2: pre-sintering;

[0013] Finely grinding, compacting, and calcining the dried powder obtained in step S1 and then cooling it in a furnace to obtain a calcined powder;

[0014] Step S3: secondary ball milling;

[0015] The calcined powder obtained in step S2 is ground again, and the resulting powder is poured into a ball mill, and ball milled with zirconium oxide balls using anhydrous ethanol as a dispersion medium for 8-12 hours at a ball mill speed of 400-500 rpm. The ball-milled slurry is placed in a drying oven at 70°C to obtain a block-like dry powder;

[0016] Step S4: tableting;

[0017] The dry powder obtained in step S3 is placed in a mortar, and a 5 wt% PVA aqueous solution is added and thoroughly mixed, followed by grinding and granulation. The granulated powder is placed in a tableting mold and compacted to obtain a ceramic green sheet.

[0018] Step S5: sintering into porcelain;

[0019] Step S5: Covering the ceramic green sheet obtained in step S4 with a layer of the block dry powder obtained in step S3, performing debinding and sintering, and then cooling in the furnace to obtain bismuth titanate niobate-based relaxor ferroelectric ceramic material.

[0020] Through the above technical solution, the preparation process of the present invention is simple, low in cost, and high in production efficiency, and is suitable for large-scale practical application production in the field of energy storage.

[0021] Furthermore, in step S2, the calcination condition is: increasing the temperature from room temperature to 800-900°C at a rate of 5°C / min and calcining for 3 hours.

[0022] Furthermore, in step S4, the tableting method is cold isostatic pressing, the pressure is 180 MPa, and the holding time is 2 minutes.

[0023] Furthermore, in step S5, the specific process of debinding and sintering is as follows:

[0024] First, the temperature was raised from room temperature to 500°C at a rate of 1°C / min, kept at that temperature for 1 hour, and then the binder was removed after cooling in the furnace.

[0025] Secondly, after the binder is removed, the steel is transferred and laid flat in a box-type muffle furnace, and the temperature is raised to 1100-1250°C at a rate of 5°C / min, kept at that temperature for 2 hours, and cooled with the furnace during the cooling process, and the sintering is completed.

[0026] Finally, an application of the ceramic material in an energy storage capacitor is provided.

[0027] Through the above technical solution, the bismuth titanate niobate-based relaxor ferroelectric energy storage ceramic of the present invention expands the energy storage application of dielectric materials.

[0028] The beneficial effects of the present invention are as follows: the bismuth titanate niobate-based relaxor ferroelectric energy storage ceramics prepared by the present invention can effectively overcome the shortcomings of high residual polarization and low breakdown electric field, and the energy storage performance is significantly better than that of undoped bismuth titanate niobate ferroelectric ceramics and other bismuth layered ferroelectric ceramic materials, while having good working environment stability. The bismuth titanate niobate-based relaxor ferroelectric energy storage ceramics of the present invention expand the energy storage applications of dielectric materials. The preparation process of the present invention is simple, low in cost, and high in production efficiency, and is suitable for large-scale practical application production in the field of energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the SEM image of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 1.

[0030] Figure 2 This is the SEM image of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 2.

[0031] Figure 3 This is the SEM image of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 3.

[0032] Figure 4 This is a hysteresis loop diagram of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 1.

[0033] Figure 5 This is the hysteresis loop diagram of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 2.

[0034] Figure 6 This is the hysteresis loop diagram of the bismuth titanate niobate-based relaxor ferroelectric ceramic material prepared in Example 3. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods in the following embodiments that do not specify specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions or parts are by weight. The energy storage density and energy storage efficiency values involved in the present invention are calculated using hysteresis loop data characterized by a ferroelectric comprehensive analyzer (Radiant, USA).

[0036] Example 1

[0037] A method for preparing a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, wherein the relaxor ferroelectric ceramic material has the general formula Bi 3-x La x TiNbO9, where x = 1.1; the specific steps are as follows:

[0038] Step S1: preparing lanthanum-doped Bi3TiNbO9 bismuth titanate niobate-based relaxor ferroelectric ceramic powder by ball milling;

[0039] According to the general formula Bi 3-x La xTiNbO9, where x = 1.1, Bi2O3, La2O3, TiO2, and Nb2O5 are weighed according to a molar ratio of 1.9:1.1:2:1 and placed in a ball mill. Anhydrous ethanol is used as the dispersion medium and ball milled with zirconia balls for 10 hours at a speed of 350 rpm. The ball-milled slurry is then placed in a drying oven at 70°C to obtain a dry powder.

[0040] Step S2: pre-sintering;

[0041] The powder obtained in step S1 was finely ground in a mortar, then placed in an alumina crucible for compaction, and the temperature was set to 900° C. at a rate of 5° C. / min and calcined for 3 h, and then cooled in the furnace to obtain the calcined powder.

[0042] Step S3: secondary ball milling;

[0043] The calcined powder obtained in step S2 was ground again, and the resulting powder was poured into a ball mill, and ball milled with zirconium oxide balls for 8 hours at a speed of 400 rpm using anhydrous ethanol as a dispersion medium. The ball-milled slurry was placed in a drying oven at 70° C. to obtain a blocky dry powder.

[0044] Step S4: tableting;

[0045] The dry powder obtained in step S3 is placed in a mortar, and a 5 wt% PVA aqueous solution is added and thoroughly mixed, followed by grinding and granulation. The granulated powder is placed in a tableting mold and compacted at a pressure of 180 MPa for 2 minutes to obtain a ceramic green sheet.

[0046] Step S5: sintering into porcelain;

[0047] The ceramic green sheet obtained in step S4 is placed in an alumina crucible and covered with a layer of the dry powder obtained in step S4. The crucible is placed in a muffle furnace, and the temperature is raised to 500°C at a sintering rate of 1°C / min, kept warm for 1 hour, and the PVA binder is removed; then the temperature is raised to 1250°C at a rate of 5°C / min, kept warm for 2 hours, and then cooled in the furnace to obtain a bismuth titanate niobate-based relaxor ferroelectric ceramic material.

[0048] Example 2

[0049] A method for preparing a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, wherein the relaxor ferroelectric ceramic material has the general formula Bi 3-x La x TiNbO9, where x = 1.0; the specific steps are as follows:

[0050] Step S1: preparing lanthanum-doped Bi3TiNbO9 bismuth titanate niobate-based relaxor ferroelectric ceramic powder by ball milling;

[0051] According to the general formula Bi 3-x La x TiNbO9, where x = 1.0, Bi2O3, La2O3, TiO2, and Nb2O5 are weighed according to a molar ratio of 2:1:2:1, placed in a ball mill, and milled with zirconia balls for 12 hours at a speed of 370 rpm using anhydrous ethanol as the dispersion medium. The milled slurry is then placed in a drying oven at 70°C to obtain a dry powder.

[0052] Step S2: pre-sintering;

[0053] The powder obtained in step S1 was finely ground in a mortar, then placed in an alumina crucible for compaction, and the temperature was set to 850°C at a rate of 5°C / min and calcined for 3 hours, and then cooled in the furnace to obtain a calcined powder.

[0054] Step S3: secondary ball milling;

[0055] The calcined powder obtained in step S2 was ground again, and the resulting powder was poured into a ball mill, and ball milled with zirconium oxide balls for 10 hours at a speed of 450 rpm using anhydrous ethanol as a dispersion medium. The ball-milled slurry was placed in a drying oven at 70° C. to obtain a blocky dry powder.

[0056] Step S4: tableting;

[0057] The dry powder obtained in step S3 is placed in a mortar, and a 5 wt% PVA aqueous solution is added and thoroughly mixed, followed by grinding and granulation. The granulated powder is placed in a tableting mold and compacted at a pressure of 180 MPa for 2 minutes to obtain a ceramic green sheet.

[0058] Step S5: sintering into porcelain;

[0059] The ceramic green sheet obtained in step S4 is placed in an alumina crucible and covered with a layer of the dry powder obtained in step S4. The crucible is placed in a muffle furnace, and the temperature is raised to 500°C at a sintering rate of 1°C / min, kept warm for 1 hour, and the PVA binder is removed; then the temperature is raised to 1220°C at a rate of 5°C / min, kept warm for 2 hours, and then cooled in the furnace to obtain a bismuth titanate niobate-based relaxor ferroelectric ceramic material.

[0060] Example 3

[0061] A method for preparing a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, wherein the relaxor ferroelectric ceramic material has the general formula Bi 3-x La x TiNbO9, where x=0; the specific steps are as follows:

[0062] Step S1: preparing lanthanum-doped Bi3TiNbO9 bismuth titanate niobate-based relaxor ferroelectric ceramic powder by ball milling;

[0063] According to the general formula Bi 3-x La x TiNbO9, where x=0, Bi2O3, La2O3, TiO2, and Nb2O5 are weighed according to a molar ratio of 3:0:2:1 and placed in a ball mill. Anhydrous ethanol is used as the dispersion medium and the milling is performed with zirconia balls for 15 hours at a speed of 400 rpm. The milled slurry is then placed in a drying oven at 70°C to obtain a dry powder.

[0064] Step S2: pre-sintering;

[0065] The powder obtained in step S1 was finely ground in a mortar, then placed in an alumina crucible for compaction, and the temperature was set to 800°C at a rate of 5°C / min and calcined for 3 hours, and then cooled in the furnace to obtain the calcined powder.

[0066] Step S3: secondary ball milling;

[0067] The calcined powder obtained in step S2 was ground again, and the resulting powder was poured into a ball mill, and ball milled with zirconium oxide balls for 12 hours at a speed of 500 rpm using anhydrous ethanol as a dispersion medium. The ball-milled slurry was then placed in a drying oven at 70°C to obtain a blocky dry powder.

[0068] Step S4: tableting;

[0069] The dry powder obtained in step S3 is placed in a mortar, and a 5 wt% PVA aqueous solution is added and thoroughly mixed, followed by grinding and granulation. The granulated powder is placed in a tableting mold and compacted at a pressure of 180 MPa for 2 minutes to obtain a ceramic green sheet.

[0070] Step S5: sintering into porcelain;

[0071] The ceramic green sheet obtained in step S4 is placed in an alumina crucible and covered with a layer of the dry powder obtained in step S4. The crucible is placed in a muffle furnace, and the temperature is raised to 500°C at a sintering rate of 1°C / min, kept warm for 1 hour, and the PVA binder is removed; then the temperature is raised to 1000°C at a rate of 5°C / min, kept warm for 2 hours, and then cooled in the furnace to obtain a bismuth titanate niobate-based relaxor ferroelectric ceramic material.

[0072] The surface morphology of the ceramics obtained by sintering Example 1, Example 2, and Example 3 was observed using a scanning electron microscope (Su500-Hitachi, Japan). The SEM images are shown in FIG. Figure 1-3 shown.

[0073] The ceramic pieces obtained by sintering in Examples 1, 2, and 3 were polished with sandpaper of 2000 mesh or above to a thickness of 0.15 mm. The polished ceramic pieces were cleaned in an ultrasonic cleaner. Then, silver paste electrodes were applied to the upper and lower surfaces of the ceramics. The electrode sintering temperature was 600°C and the sintering time was 20 min. Finally, the hysteresis loops of the ceramics of Examples 1, 2, and 3 were characterized using a ferroelectric comprehensive analyzer (Radiant II, USA). Figure 4-6 As shown. SEM images of ceramics obtained by sintering Examples 1, 2, and 3 ( Figure 1-3 ) It can be seen that the ceramic grain boundaries are obvious, the grains are tightly arranged, and no obvious pores appear, indicating that the ceramic materials prepared in Examples 1, 2, and 3 have good sintering quality.

[0074] In summary, the hysteresis loop of the ceramic material prepared in Example 1 measured at room temperature is as follows: Figure 4 As shown in the figure, the energy storage calculation formula shows that when the maximum breakdown electric field is 480kV / cm, the available energy storage density is 5.23J / cm 3 , the energy storage efficiency is 89.1%. The hysteresis loop of the ceramic material prepared in Example 2 measured at room temperature is as follows Figure 5 As shown in the figure, the energy storage calculation formula shows that when the maximum breakdown electric field is 520kV / cm, the available energy storage density is 6.7J / cm 3 , the energy storage efficiency is 80.8%. The hysteresis loop of the ceramic material prepared in Example 3 measured at room temperature is as follows Figure 4 As shown in the figure, the energy storage calculation formula shows that when the maximum breakdown electric field is 220kV / cm, the available energy storage density is 1.04J / cm 3 , the energy storage efficiency is 40.5%.

[0075] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage, wherein the relaxor ferroelectric ceramic material has the general formula Bi 3-x La x TiNbO9, where x = 1.1; The relaxor ferroelectric ceramic material is prepared by lanthanum doping Bi3TiNbO9 based on the solid phase sintering method; the lanthanum doping is carried out by doping with lanthanum oxide; the relaxor ferroelectric ceramic material Bi 3-x La x The molar ratio of each raw material in TiNbO9 is Bi2O3:La2O3:TiO2:Nb2O5, which is 1.9:1.1:2:1; The preparation method comprises the following steps: Step S1: preparing lanthanum-doped Bi3TiNbO9 bismuth titanate niobate-based relaxor ferroelectric ceramic powder by ball milling; The raw materials were respectively prepared according to the general formula Bi 3-x La x TiNbO9, x=1.1, was weighed and prepared, placed in a ball mill, and ball milled with zirconium oxide balls using anhydrous ethanol as the dispersion medium. The ball milling time was 10-15 hours at a ball milling speed of 350-400 rpm. The ball-milled slurry was placed in a drying oven at 70°C to obtain a dry powder. Step S2: pre-sintering; Finely grinding, compacting, and calcining the dried powder obtained in step S1 and then cooling it in a furnace to obtain a calcined powder; Step S3: secondary ball milling; Grind the calcined powder obtained in step S2 again, and pour the resulting powder into a ball mill, use anhydrous ethanol as a dispersion medium, and ball mill with zirconium oxide balls for 8-12 hours at a ball mill speed of 400-500 rpm. Place the ball-milled slurry in a drying oven at 70°C to obtain a blocky dry powder; Step S4: tableting; The dry powder obtained in step S3 is placed in a mortar, and a 5 wt% PVA aqueous solution is added and thoroughly mixed, followed by grinding and granulation. The granulated powder is placed in a tableting mold and compacted to obtain a ceramic green sheet. Step S5: sintering into porcelain; Covering the ceramic green sheet obtained in step S4 with a layer of the block dry powder obtained in step S3, performing debinding and sintering, and cooling in the furnace to obtain a bismuth titanate niobate-based relaxor ferroelectric ceramic material; In step S2, the calcination conditions are: increasing the temperature from room temperature to 800-900°C at a rate of 5°C / min and calcining for 3 hours; In step S5, the specific process of debinding and sintering is as follows: First, the temperature was raised from room temperature to 500°C at 1°C / min, kept at that temperature for 1 hour, and then cooled in the furnace before debinding was completed. Secondly, after the binder is removed, the steel is transferred and laid flat in a box-type muffle furnace, and the temperature is raised to 1100-1250°C at a rate of 5°C / min, kept at that temperature for 2 hours, and cooled with the furnace during the cooling process, and the sintering is completed.

2. The method for preparing bismuth titanate niobate-based relaxor ferroelectric ceramic material for energy storage according to claim 1, characterized in that: In step S4, the tableting method is cold isostatic pressing, the pressure is 180 MPa, and the holding time is 2 minutes.

3. Use of the ceramic material prepared by the preparation method according to claim 1 in energy storage capacitors.

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