A perovskite two-phase composite relaxor ferroelectric ceramic with excellent dielectric energy storage performance and a preparation method thereof

Abstract

The application provides a perovskite two-phase composite relaxor ferroelectric ceramic with excellent dielectric energy storage performance and a preparation method thereof, and belongs to the technical field of relaxor ferroelectric ceramics. 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3 (0.05<=x<=0.15, 0.2<=y<=0.5). The dielectric ceramic has high energy storage density and high energy storage efficiency, excellent temperature and frequency stability characteristics, and has good application potential in the energy storage field, such as electric energy recovery systems of electric vehicles, electronic equipment, power network load balancing and frequency modulation systems and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of relaxor ferroelectric ceramic dielectric energy storage materials, and particularly relates to a perovskite two-phase composite relaxor ferroelectric ceramic with excellent energy storage performance and a preparation method thereof. BACKGROUND

[0002] Energy storage technology is crucial in the context of sustainability and energy transition, particularly the demand for high-performance dielectric energy storage materials. With the integration of renewable energy sources such as solar and wind power, the development of efficient and high-density energy storage technology becomes urgent. Traditional energy storage such as lithium-ion batteries is limited in terms of energy release rate, lifespan, and environmental stability. Dielectric energy storage capacitors, although fast in charging and discharging, have low energy density and storage efficiency. Relaxor ferroelectric dielectric ceramic materials show great potential in simultaneously achieving high energy density and high storage efficiency characteristics.

[0003] The development of relaxor ferroelectric dielectric ceramic materials meets the goals of energy conservation and sustainable development. They contribute to improving energy utilization efficiency and new smart grid technologies. In power electronics, hybrid electric vehicles, and pulsed power applications, these materials can significantly improve energy efficiency and system performance. Therefore, they are key materials for addressing energy storage challenges and driving future energy technology innovation. However, the existing relaxor ferroelectric ceramics have low breakdown field strength, low energy storage density, and low efficiency under high electric field. SUMMARY

[0004] The technical problem to be solved by the present application is that the relaxor ferroelectric ceramics have low breakdown field strength, low energy storage density, and low efficiency under high electric field. Therefore, a perovskite two-phase composite relaxor ferroelectric ceramic with excellent dielectric energy storage performance and a preparation method thereof are provided. By introducing several elements with large differences in ionic radius and suitable content ratios at the A site of the perovskite structure, such as Ba 2+ Na + Bi 3+ Cd 2+ This results in phase separation to form a perovskite two-phase composite structure with a suitable ratio. The results show that this structure improves the breakdown strength of the ceramic material without reducing the polarization strength.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In a first aspect, a perovskite two-phase composite relaxor ferroelectric ceramic with excellent dielectric energy storage performance is provided, having a chemical composition of (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3.

[0007] The present application is 0.05≤x≤0.15, 0.2≤y≤0.5, x may be 0.05, 0.10, 0.15, y may be 0.2, 0.4, for example.

[0008] Preferably, 0.1≤x≤0.15, 0.3≤y≤0.5.

[0009] More preferably, x=0.1, y=0.4.

[0010] Under the above more preferred scheme, the energy storage efficiency can be stabilized at more than 90%, and under an electric field of 99kV / mm, the energy storage density is 23.6J / cm 3 , and the energy storage efficiency is 92.4%.

[0011] Further, in the XRD spectrum of the perovskite two-phase composite relaxor ferroelectric ceramic, all perovskite characteristic peaks have two diffraction peaks; it is shown that the perovskite two-phase composite relaxor ferroelectric ceramic has a perovskite two-phase composite structure, which is beneficial to improve the energy storage performance under high electric field.

[0012] Further, the grain size of the perovskite two-phase composite relaxor ferroelectric ceramic is 0.3-7.0μm, preferably 0.58-4.16μm.

[0013] In a second aspect, a preparation method of the perovskite two-phase composite structure relaxor ferroelectric ceramic is provided.

[0014] Specifically comprising the following steps:

[0015] S1, according to (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3 (0.05≤x≤0.15, 0.2≤y≤0.5)

[0016] The stoichiometric ratio of Bi2O3, Na2CO3, BaCO3, CdO, TiO2 and ZrO2 is weighed into a ball mill jar, and an organic solvent is added for primary ball milling;

[0017] S2, the mixture after primary ball milling is dried, ground, and then calcined (such as in a muffle furnace);

[0018] S3, the calcined powder is again subjected to secondary ball milling;

[0019] S4, the powder obtained after secondary ball milling and drying is added with a binder, ground, granulated, sieved, and pressed into a green body;

[0020] S5, the green body is degreased and sintered.

[0021] Further, the embryos in S4 can be placed in a crucible and put into a muffle furnace for degassing and sintering.

[0022] Preferably, the organic solvent in S1 is ethanol.

[0023] Further preferably, the amount of ethanol in S1 is 100-200 mL.

[0024] Preferably, the conditions of the first ball milling in S1 include a ball milling time of 12-16 h and a rotation speed of 300-500 rpm.

[0025] Preferably, the conditions of the calcination in S2 include a temperature of 700-900℃ and a time of 2-3 h.

[0026] Preferably, the conditions of the second ball milling in S3 include a ball milling time of 12-16 h and a rotation speed of 300-500 rpm.

[0027] Preferably, the binder in S4 is polyvinyl alcohol.

[0028] Preferably, the binder is a polyvinyl alcohol aqueous solution with a mass fraction of 3%-5%, and the mass ratio of the binder to the powder obtained after the second ball milling and drying is 1:5-15.

[0029] Preferably, the sieving in S4 uses a 300-400 mesh, preferably 400 mesh, sieve.

[0030] Preferably, the degassing conditions in S4 include a temperature of 500-600℃, a time of 2-3 h, and a heating rate of 3-5℃ / min.

[0031] Preferably, the sintering conditions in S4 include a temperature of 1000-1200℃, a time of 2-3 h, and a heating rate of 3-5℃ / min.

[0032] The beneficial effects of the above technical solutions of the present application are as follows:

[0033] The present application introduces Ba 2+ Na + Bi 3+ Cd 2+ ions, these ions are very different in properties and cannot be dissolved into a single phase solid solution, resulting in the appropriate degree of separation of the perovskite phase, forming a perovskite two-phase composite structure with an appropriate ratio. The two perovskite phases formed have relaxor ferroelectric properties, resulting in a large macroscopic spontaneous polarization intensity. At the same time, Zr with a large ionic radius and an appropriate content ratio is introduced at the B position. 4+ The ions increase local chemical disorder, disrupting the long-range, ordered macroscopic ferroelectric domains within the two-phase grains and forming polar nanodomains. This accelerates the electric field response while effectively reducing the energy loss caused by domain reversal, giving both perovskite phases typical relaxor ferroelectric characteristics. Furthermore, the resulting two phases are randomly distributed across different grains, which contributes to an increase in breakdown field strength.

[0034] Thanks to its rational chemical composition and perovskite two-phase composite structure, the relaxor ferroelectric ceramics of the present invention have high breakdown field strength and high polarization strength. Ultimately, the energy storage efficiency can be stabilized at over 90%, and the energy storage density can reach 23.6 J / cm at an electric field of 99 kV / mm. 3 , the energy storage efficiency can reach 92.4%, achieving excellent results. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the XRD image of the perovskite two-phase composite relaxor ferroelectric ceramic prepared in Example 1;

[0036] Figure 2 1 is the hysteresis loop of the perovskite two-phase composite relaxor ferroelectric ceramic prepared in Example 1;

[0037] Figure 3 The energy storage performance of the perovskite two-phase composite relaxor ferroelectric ceramic prepared in Example 1 changes with the applied electric field;

[0038] Figure 4 This is a SEM image of the perovskite two-phase composite relaxor ferroelectric ceramic prepared in Example 1;

[0039] Figure 5 The perovskite two-phase composite relaxor ferroelectric ceramic prepared in Example 1 Figure 4 SEM image and EDS image. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0041] The present invention is a new type of dielectric energy storage material with a capacity of 6.39 to 23.6 J / cm 3energy storage density of 23.6 J / cm 3 and energy storage efficiency of 92.4%. The dielectric ceramic has high energy storage density and high energy storage efficiency, excellent temperature and frequency stability characteristics, and has good application potential in the field of energy storage, such as electric vehicle power recovery system, electronic equipment, and power network load balancing and frequency modulation system.

[0042] Example 1:

[0043] The (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3 (x = 0.05-0.15, y = 0.4) is prepared by the method. Bi2O3, Na2CO3, BaCO3, CdO, TiO2, and ZrO2 are weighed according to the chemical dosage ratio, poured into a ball mill jar, 150 ml of ethanol is added, and one-time ball milling is performed for 12 h at a speed of 300-500 rpm. The milled sample is sequentially dried, ground, and then placed in a muffle furnace for calcination at a temperature of 820 ℃ for 2 h. The calcined powder is poured into a mortar and subjected to secondary ball milling for 12 h at a speed of 300-500 rpm. After drying, an appropriate amount of 5wt% polyvinyl alcohol aqueous solution binder (binder to sample mass ratio of 1:10) is added, ground, granulated, and poured into a 400 mesh sieve for sieving. The sieved powder is pressed into a green body using a mold and placed in a muffle furnace for degassing at a heating rate of 5 ℃ / min, a degassing temperature of 550 ℃, and a time of 2.5 h. Subsequently, sintering is performed at a heating rate of 5 ℃ / min, a sintering temperature of 1120 ℃, and a time of 2 h. After cooling, a perovskite two-phase composite relaxor ferroelectric ceramic with excellent dielectric energy storage performance is obtained.

[0044] In order to test the energy storage performance, the thickness of the ceramic sheet is polished to 50-80 μm. Gold electrodes are plated on the upper and lower surfaces of the ceramic using an ion sputtering instrument. The ion sputtering conditions include: gold target, current of 10 mA, and time of 300 s.

[0045] Figure 1 The XRD images of the perovskite two-phase composite relaxor ferroelectric ceramics with y = 0.4 and x = 0.05, 0.1, and 0.15 prepared in this example are shown in the figure. As can be seen from the figure, all the perovskite characteristic peaks have two diffraction peaks, indicating that the ceramic is composed of two perovskite phases, and the second phase peak intensity gradually increases with the increase of x. This is because the doping of Cd 2+ has a significant effect on the phase structure of the ferroelectric ceramic, and this two-phase composite structure makes it have high breakdown electric field strength.​

[0046] Figure 2 The monopolar hysteresis loop of the x=0.1, y=0.4 perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example is shown. The material exhibits ferroelectric polarization characteristics of low hysteresis and large polarization value, resulting in high energy storage efficiency and large energy storage density.

[0047] Figure 3 The energy storage performance curve of the x=0.1, y=0.4 perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example as a function of applied electric field is shown. As can be seen from the figure, the perovskite two-phase composite relaxor ferroelectric ceramic described in this application exhibits high energy storage efficiency, and its energy storage efficiency can be stabilized at more than 91%; and under an electric field of 99 kV / mm, the energy storage density can reach 23.6 J / cm 3 , and the energy storage efficiency can reach 92.4%.

[0048] Figure 4 The SEM picture of the x=0.1, y=0.4 perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example is shown. The light-colored regions in the figure are randomly distributed with second-phase grains, and the grain size is 0.58-4.16 μm, with an average grain size of 2 μm.

[0049] Figure 5 The EDS map of Figure 4 , as can be seen from the figure, the Cd element enrichment region corresponds to the light-colored grain in Figure 4 , proving that the perovskite two-phase is distributed in different grains. This distribution increases the grain boundary phase from the originally single grain boundary phase, thereby enhancing the breakdown strength of the material.

[0050] Example 2:

[0051] The method of Reference Example 1 is referred to, except that the ceramic material composition is:

[0052] (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3(x=0.05, y=0.4), and the corresponding Bi2O3, Na2CO3, BaCO3, CdO, ZrO2, TiO2 are weighed according to the chemical dosage ratio.

[0053] It is tested that the perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example has an energy storage density of 9.21 J / cm 3 and an energy storage efficiency of 81.4% under an electric field of 47 kV / mm. In its XRD spectrum, all the perovskite characteristic peaks have two diffraction peaks. Its grain size is 1.28-6.91 μm.

[0054] Example 3

[0055] The method of Example 1 was followed except that the ceramic material composition was (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3(x=0.15, y=0.4). Bi2O3, Na2CO3, BaCO3, CdO, ZrO2, TiO2 were weighed according to the chemical dosage ratio respectively.

[0056] The perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example was tested to have a stored energy density of 12.47 J / cm 3 and a stored energy efficiency of 88.7% under an electric field of 72 kV / mm. In the XRD spectrum, all perovskite characteristic peaks have two diffraction peaks. The grain size is 0.69-3.97 μm.

[0057] Example 4

[0058] The method of Example 1 was followed except that the ceramic material composition was (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3(x=0.1, y=0.2). Bi2O3, Na2CO3, BaCO3, CdO, ZrO2, TiO2 were weighed according to the chemical dosage ratio respectively.

[0059] The perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example was tested to have a stored energy density of 12.64 J / cm 3 and a stored energy efficiency of 89.1% under an electric field of 62 kV / mm. In the XRD spectrum, all perovskite characteristic peaks have two diffraction peaks.

[0060] Example 5

[0061] The method of Example 1 was followed except that the ceramic material composition was (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3(x=0.15, y=0.2). Bi2O3, Na2CO3, BaCO3, CdO, ZrO2, TiO2 were weighed according to the chemical dosage ratio respectively.

[0062] The perovskite two-phase composite relaxor ferroelectric ceramic prepared in this example was tested to have a stored energy density of 6.73 J / cm 3 and a stored energy efficiency of 86.7% under an electric field of 52 kV / mm. In the XRD spectrum, all perovskite characteristic peaks have two diffraction peaks.

[0063] Comparative Example 1:

[0064] The method of Example 1 was followed except that the ceramic material composition was (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3 (x=0, y=0.4) and Bi2O3, Na2CO3, BaCO3, ZrO2, TiO2 were weighed according to the chemical dosage ratio.

[0065] It was tested that the perovskite relaxor ferroelectric ceramic prepared in this comparative example had a stored energy density of 8.31 J / cm 3 and a stored energy efficiency of 77.5% under an electric field of 58 kV / mm. In the XRD spectrum, all perovskite characteristic peaks had only one diffraction peak. The grain size was 0.27-1.61 μm, and the average grain size was 0.91 μm.

[0066] Comparative Example 2:

[0067] The method of Example 1 was followed except that the ceramic material composition was (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3 (x=0.2, y=0.2) and Bi2O3, Na2CO3, BaCO3, CdO, ZrO2, TiO2 were weighed according to the chemical dosage ratio.

[0068] It was tested that the perovskite relaxor ferroelectric ceramic prepared in this comparative example had a stored energy density of 0.63 J / cm 3 and a stored energy efficiency of 95.4% under an electric field of 11 kV / mm. In the XRD spectrum, all perovskite characteristic peaks had two diffraction peaks.

[0069] From the above examples and comparative examples, it can be seen that only the ceramic material with the specific composition of the present application can exhibit excellent stored energy performance. These are the preferred embodiments of the present application. It should be noted that general skilled persons in the technical field can make some improvements and modifications without deviating from the principles of the present application, and these improvements and modifications should also be included in the protection scope of the present application.

Claims

1. A perovskite two-phase composite relaxor ferroelectric ceramic having excellent dielectric energy storage properties, characterized by, with the chemical composition (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3, 0.05≤x≤0.15, 0.2≤y≤0.

5.

2. The perovskite two-phase composite relaxor ferroelectric ceramic of claim 1, wherein, 0.1≤x≤0.15, 0.3≤y≤0.

5.

3. The relaxor ferroelectric ceramic of claim 1, wherein, In the XRD spectrum of the perovskite two-phase composite relaxor ferroelectric ceramic, all perovskite characteristic peaks have two diffraction peaks.

4. The relaxor ferroelectric ceramic of claim 1, wherein, The grain size of the perovskite two-phase composite relaxor ferroelectric ceramic is 0.58-4.16 μm.

5. A method of producing the relaxor ferroelectric ceramic as claimed in any one of claims 1 to 4, characterized by, Comprising the following steps: S1, according to (1-x-y)Bi 0.5 Na 0.5 TiO3-yBaTiO3-xCdZrO3, 0.05≤x≤0.15, 0.2≤y≤0.5, stoichiometrically weigh Bi2O3, Na2CO3, BaCO3, CdO, TiO2, ZrO2, pour them into a ball mill jar, and add an organic solvent for primary ball milling; S2, dry and grind the mixture after primary ball milling, and then calcine; S3, re-ball mill the calcined powder again; S4, grind, granulate and sieve the powder obtained after secondary ball milling and drying by adding a binder, and press it into a green body; S5, degas and sinter the green body.

6. The preparation method according to claim 5, characterized in that The organic solvent in S1 is ethanol, and the conditions of the primary ball milling in S1 and the secondary ball milling in S3 each independently include a ball milling time of 12-16 h and a rotation speed of 300-500 rpm.

7. The preparation method according to claim 5, characterized in that The calcining conditions in S2 include a temperature of 700-900 ℃ and a time of 2-3 h.

8. The preparation method according to claim 5, characterized in that The binder in S4 is a polyvinyl alcohol aqueous solution with a mass fraction of 3%-5%, and the mass ratio of the binder to the powder obtained after secondary ball milling and drying is 1:5-15.

9. The preparation method according to claim 5, characterized in that The sieve used in S4 is a 300-400 mesh sieve.

10. The method of claim 5, wherein, The degassing conditions in S5 include a temperature of 500-600 ℃, a time of 2-3 h, and a heating rate of 3-5 ℃ / min; and the sintering conditions in S5 include a temperature of 1000-1200 ℃, a time of 2-3 h, and a heating rate of 3-5 ℃ / min.

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