A NaNbO3-based ceramic material with high energy storage density and efficiency and its preparation method

Abstract

This invention belongs to the technical field of dielectric energy storage ceramic materials, and relates to a NaNbO3-based ceramic material with high energy storage density and efficiency and its preparation method. The chemical formula of the NaNbO3-based ceramic material is: (1- x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 The preparation method for NaNbO3 includes: mixing Na2CO3, Nb2O5, Bi2O3, NiO, MgO, ZrO2, Ta2O5, and HfO2, then adding zirconium oxide microspheres and alcohol, stirring, and drying to obtain a mixed powder; ball milling the pre-calcined powder and drying it again; pressing the dried powder into sheets; and sintering the pressed sheets to obtain NaNbO3-based ceramics. This invention uses a solid-state method to prepare ceramics. When the doping amount is 0.20 mol, a secondary phase appears in the ceramic sample; compared with pure NaNbO3, the energy storage efficiency is increased by about 30 times; when the doping amount is 0.10 mol, the energy storage density of NN-0.1BM5 is 5.1 J·cm⁻¹. ‑3 The energy storage efficiency is 94.0%.

Description

Technical Field

[0001] This invention belongs to the field of dielectric energy storage ceramic materials technology, specifically relating to a NaNbO3-based ceramic material with high energy storage density and efficiency and its preparation method. Background Technology

[0002] Dielectric capacitors possess ultra-high power density, ultra-fast charge / discharge rates, and excellent temperature insensitivity, making them a promising candidate for applications in electronic and power systems. However, compared to electrochemical capacitors, their energy density is relatively low, hindering their widespread use in the miniaturization and integration of electronic devices. Evaluation metrics for energy storage performance include recoverable energy density and efficiency; therefore, to achieve higher recoverable energy density and efficiency while simultaneously meeting significant performance requirements... P m Negligible P r and extremely high breakdown electric field ( E b Antiferroelectrics are crucial. To date, compared to other dielectric materials (including linear dielectrics, ferroelectrics, and relaxor ferroelectrics), antiferroelectrics have become highly promising energy storage devices due to their unique double hysteresis loop characteristics. Antiferroelectrics have the following advantages: a) The antiparallel polarization configuration leads to near-zero [electricity / temperature]. P r b. The electric field-induced polarized ferroelectric state brings high... P m c. Electric field-induced antiferroelectric-ferroelectric phase transitions promote the formation of concave polarization / depolarization processes. Sodium niobate (NN) is considered to have significant application potential in the field of energy storage due to its high band gap, large polarization intensity, and low bulk density. Currently, various methods have been employed to regulate the energy storage performance of NN-based ceramic materials.

[0003] However, despite the good energy storage performance of these ceramics at room temperature, achieving both high energy density and high energy storage efficiency remains a huge challenge.

[0004] Therefore, a dielectric material that can simultaneously achieve high energy storage density and high energy storage efficiency is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides the following technical solution: a NaNbO3-based ceramic material with high energy storage density and efficiency, wherein the chemical formula of the NaNbO3-based ceramic material is: (1- x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2O3, of which x for Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 The molar percentage of O3; x The value range is 0 to 0.20.

[0006] Preferably, the x The values ​​include: 0, 0.05, 0.10, 0.15, and 0.20.

[0007] More preferably, the aforementioned x When the value is 0.10, the energy storage density of NaNbO3-based ceramic materials is greater than 5 J·cm⁻¹. -3 Its energy storage efficiency is higher than 93%.

[0008] This invention also discloses a method for preparing NaNbO3-based ceramic materials with high energy storage density and efficiency. This method, used to prepare the aforementioned NaNbO3-based ceramic materials, includes the following steps: Step S1: After mixing Na2CO3, Nb2O5, Bi2O3, NiO, MgO, ZrO2, Ta2O5, and HfO2, add zirconium oxide microspheres and alcohol, stir, and dry to obtain a mixed powder.

[0009] Step S2: The mixed powder obtained in step S1 is ball-milled after pre-calcination and then dried again.

[0010] Step S3: Press the powder obtained from drying in step S2 into sheets.

[0011] Step S4: The pressed sheet obtained in step S3 is sintered to obtain NaNbO3-based ceramic.

[0012] Preferably, the stirring speed in step S1 is 280–320 r·min. -1 .

[0013] Preferably, the pre-firing temperature in step S2 is 820-880°C, and the pre-firing time is 3-5 hours.

[0014] Preferably, the tablet in step S3 is formed by pressing under a cold isostatic pressure of 190-210 MPa.

[0015] Preferably, the sheet pressed in step S3 is a circular sheet with a diameter of 9-15 mm and a thickness of 0.5-1.5 mm.

[0016] Preferably, the sintering temperature in step S4 is 1170–1230 °C, and the sintering time is 3–5 h.

[0017] The beneficial effects of this invention are: This invention successfully prepared (1- x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 In NaNbO3 ceramics, a secondary phase appeared in the ceramic sample when the doping concentration was 0.20 mol. Compared with pure NaNbO3, the energy storage efficiency of NN-0.1BM5 ceramics was improved by approximately 30 times. When the doping concentration was 0.10 mol, the energy storage density of NN-0.1BM5 ceramics was 5.1 J·cm⁻¹. -3 The energy storage efficiency is 94.0%. Transmission electron microscopy analysis revealed that the addition of BM5 broke down the long-range ordered antiferroelectric domains into polar nanodomains, which lowered the energy barrier and thus achieved lower energy efficiency. P r Therefore, the present invention can simultaneously achieve high energy storage density and high energy storage efficiency. Attached Figure Description

[0018] Figure 1 The XRD patterns of the ceramics in the embodiments and comparative example 1 of the present invention, which describe a NaNbO3-based ceramic material with high energy storage density and efficiency and its preparation method. Figure 2 This is a SEM image of NaNbO3-doped ceramics in an embodiment of the present invention; Figure 3 This is a SEM image of the NaNbO3 ceramic in Comparative Example 1 of the present invention; Figure 4 This is a PE curve diagram of NaNbO3-doped ceramics in an embodiment of the present invention; Figure 5 This is a PE curve of the NaNbO3 ceramic in Comparative Example 1 of the present invention; Figure 6 The dielectric temperature spectrum of the NaNbO3-doped ceramic in an embodiment of the present invention; Figure 7 The dielectric temperature spectrum of NaNbO3 ceramic in Comparative Example 1 of this invention; Figure 8 This is a TEM image of the NaNbO3-doped ceramic in Example 2 of the present invention; Figure 9 This is a TEM image of the NaNbO3 ceramic in Comparative Example 1 of the present invention. Detailed Implementation

[0019] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] like Figures 1-9 As shown, the preparation method of a NaNbO3-based ceramic with high energy storage density and efficiency according to this embodiment includes the following steps: S1: After mixing Na2CO3, Nb2O5, Bi2O3, NiO, MgO, ZrO2, Ta2O5, and HfO2, zirconium oxide microspheres and alcohol are added, stirred, and dried to obtain a mixed powder. S2: The mixed powder obtained in step S1 is ball-milled again after pre-calcination, following the ball-milling operation in step S1, and then dried. S3: Press the powder obtained from drying in step S2 into round discs; S4: Sinter the discs obtained in step S3 to obtain NaNbO3-based ceramics.

[0021] Furthermore, the chemical formula of the NaNbO3-based ceramic in step S1 is: (1- x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 O3, of which x for Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 The molar percentage of O3, and x= 0, 0.05, 0.10, 0.15, 0.20.

[0022] Furthermore, the stirring speed in step S1 is 300 r·min. -1 .

[0023] Furthermore, in step S2, the pre-firing temperature is 850 °C and the pre-firing time is 4 h.

[0024] Furthermore, in step S3, the disc is pressed into shape under cold isostatic pressure of 190-210 MPa.

[0025] Furthermore, in step S3, the diameter of the disc is 12 mm and the thickness is 1 mm.

[0026] Furthermore, in step S4, the sintering temperature is 1170-1230 ℃ and the sintering time is 4 h.

[0027] Example In the embodiments, the molar ratios of the initial ceramic raw materials of the embodiments and comparative examples are shown in Table 1.

[0028]

[0029] Example 1: The preparation steps of NaNbO3-based ceramics in this example are as follows: Step 1: According to the ceramic powder formulation shown in Table 1 for this embodiment, the ceramic powder materials are mixed in the following molar ratios: 0.468 mol Na2CO3, 0.468 mol Nb2O5, 0.025 mol Bi2O3, 0.01 mol NiO, 0.01 mol MgO, 0.005 mol ZrO2, 0.005 mol Ta2O5, and 0.01 mol HfO2. Step 2: at 300 r·min -1 The mixture was stirred at a certain speed for 12 hours, and then dried at 80 ℃ for 24 hours to obtain a mixed powder. Step 3: The obtained mixed powder is pre-calcined at 850 °C for 4 h. The pre-calcined powder is then ball-milled according to the ball milling operation in Step 2 and dried again.

[0030] Step 4: Press the powder dried in Step 3 into a disc under a cold isostatic pressure of 190-210 MPa; Step 5: at 3 ℃·min -1 The temperature was increased to 1230 °C and held for 240 min. This yielded the NaNbO3-based ceramic of this embodiment.

[0031] Example 2: The preparation steps of NaNbO3-based ceramics in this example are as follows: Step 1: According to the ceramic powder formulation shown in Table 1 for this embodiment, the ceramic powder materials are mixed in the following molar ratios: 0.437 mol Na2CO3, 0.437 mol Nb2O5, 0.049 mol Bi2O3, 0.019 mol NiO, 0.019 mol MgO, 0.01 mol ZrO2, 0.01 mol Ta2O5, and 0.019 mol HfO2. Step 2: at 300 r·min -1 The mixture was stirred at a certain speed for 12 hours, and then dried at 80 ℃ for 24 hours to obtain a mixed powder. Step 3: The obtained mixed powder is pre-calcined at 850 °C for 4 h. The pre-calcined powder is then ball-milled according to the ball milling operation in Step 2 and dried again.

[0032] Step 4: Press the powder dried in Step 3 into a disc under a cold isostatic pressure of 190-210 MPa; Step 5: at 3 ℃·min -1 The temperature was increased to 1210 °C and held for 240 min. This yielded the NaNbO3-based ceramic of this embodiment.

[0033] Example 3: The preparation steps of NaNbO3-based ceramics in this example are as follows: Step 1: According to the ceramic powder formulation shown in Table 1 for this embodiment, the ceramic powder materials are mixed in the following molar ratios: 0.407 mol Na2CO3, 0.407 mol Nb2O5, 0.072 mol Bi2O3, 0.029 mol NiO, 0.029 mol MgO, 0.014 mol ZrO2, 0.014 mol Ta2O5, and 0.029 mol HfO2. Step 2: at 300 r·min -1 The mixture was stirred at a certain speed for 12 hours and then dried at 80 °C for 24 hours to obtain a mixed powder. Step 3: The obtained mixed powder is pre-calcined at 850 °C for 4 h. The pre-calcined powder is then ball-milled according to the ball milling operation in Step 2 and dried again.

[0034] Step 4: Press the powder dried in Step 3 into a disc under a cold isostatic pressure of 190-210 MPa; Step 5: at 3 ℃·min -1 The temperature was increased to 1190 °C and held for 240 min. This yielded the NaNbO3-based ceramic of this embodiment.

[0035] Example 4: The preparation steps of NaNbO3-based ceramics in this example are as follows: Step 1: According to the ceramic powder formulation shown in Table 1 for this embodiment, the ceramic powder materials are mixed in the following molar ratios: 0.377 mol Na2CO3, 0.377 mol Nb2O5, 0.094 mol Bi2O3, 0.038 mol NiO, 0.038 mol MgO, 0.019 mol ZrO2, 0.019 mol Ta2O5, and 0.038 mol HfO2. Step 2: at 300 r·min -1 The mixture was stirred at a certain speed for 12 hours, and then dried at 80°C for 24 hours to obtain a mixed powder. Step 3: The obtained mixed powder is pre-calcined at 850 °C for 4 h. The pre-calcined powder is then ball-milled according to the ball milling operation in Step 2 and dried again.

[0036] Step 4: Press the powder dried in Step 3 into a disc under a cold isostatic pressure of 190-210 MPa; Step 5: at 3 ℃·min -1 The temperature was increased to 1170 °C and held for 240 min. This yielded the NaNbO3-based ceramic of this embodiment.

[0037] Comparative Example 1: The preparation steps of the NaNbO3-based ceramic in this comparative example are as follows: Step 1: According to the ceramic powder formulation shown in Table 1 for this embodiment, the ceramic powder materials are mixed in the following molar ratios: 0.5 mol Na2CO3, 0.5 mol Nb2O5, 0.0 mol Bi2O3, 0.0 mol NiO, 0.0 mol MgO, 0.0 mol ZrO2, 0.0 mol Ta2O5, and 0.0 mol HfO2. Step 2: at 300 r·min -1 The mixture was stirred at a certain speed for 12 hours, and then dried at 80 ℃ for 24 hours to obtain a mixed powder. Step 3: The obtained mixed powder is pre-calcined at 850 °C for 4 h. The pre-calcined powder is then ball-milled according to the ball milling operation in Step 2 and dried again.

[0038] Step 4: Press the powder dried in Step 3 into a disc under a cold isostatic pressure of 190-210 MPa; Step 5: at 3 ℃·min -1 The temperature was increased to 1300 °C and held for 240 min. This yielded the NaNbO3-based ceramic of this embodiment.

[0039] Performance testing The sodium niobate ceramics obtained in the examples were subjected to the following performance tests: (1) Performance testing includes energy storage density ( W rec ), energy storage efficiency ( η ), dielectric constant (ε'), dielectric loss (tanδ); The test results of energy storage performance data for each embodiment are shown in Table 2:

[0040] (1) XRD analysis The XRD patterns of Examples 1, 2, 3, 4, and Comparative Example 1 are as follows: Figure 1 As shown. From Figure 1 As can be seen, the components of Comparative Example 1 and Examples 1-3 are all pure perovskite structures. However, when the component is Example 4, a second phase appears, mainly because Bi(Ni) 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 O3 entered the NaNbO3 ceramic beyond its solid solubility. Figure 1 The image shows a magnified view of the region with an angle of 30.5-34.5°. We can observe that as the doping content increases, the main peak gradually shifts to a lower angle, indicating that the lattice spacing gradually increases. This phenomenon mainly originates from Nb at the B sites. 5+ (0.64 Å) was affected by Ni, which has a larger average ionic radius. 2+ (0.69 Å), Mg 2+ (0.72 Å), Zr 4+ (0.72 Å), Ta 5+ (0.64 Å) and Hf 4+ The partial substitution of (0.71Å) leads to an increase in BO bond length and expansion of the unit cell volume, which in turn causes the diffraction peak to shift to a lower angle.

[0041] (2) SEM analysis; SEM images of Examples 1-4 are shown below. Figure 2 (In the figure, a, b, c, and d correspond to Examples 1, 2, 3, and 4 in sequence.) The SEM image of Comparative Example 1 is shown below. Figure 3 As shown in the figure, the surface microstructure of NaNbO3-based ceramics with different doping contents is illustrated. It can be observed that the undoped ceramic sample has very large grains and exhibits a square grain morphology. The average grain size can be calculated from the linear intercept, and the average grain sizes are 11.32 μm, 6.0 μm, 4.45 μm, 5.09 μm, and 7.97 μm, respectively, for Comparative Example 1 and Examples 1-4. It can be found that with increasing doping content, the grain size of NaNbO3 ceramics first decreases and then increases. Furthermore, all NaNbO3 ceramics exhibit a dense structure, and no pores were observed in the SEM images. However, some second-phase particles were found attached to the surface of Comparative Example 4, which is consistent with the XRD results.

[0042] (3) Ferroelectric performance analysis Examples 1-4 P - E Curve graph as Figure 4(In the figure, a, b, c, and d correspond to Examples 1, 2, 3, and 4 in sequence.) As shown in Comparative Example 1... P - E Curve graph as Figure 5 As shown. It is well known that pure NN phases, due to the similar potential energies of the antiferroelectric P phase and the ferroelectric Q phase at room temperature, possess an irreversible hysteresis loop, thus exhibiting a ferroelectric hysteresis loop, as shown. Figure 5 As shown, it can be seen that it exhibits a breakdown electric field of 34.4 uC·cm. -2 It exhibits maximum polarization, but due to the presence of large antiferroelectric domains, it cannot quickly return to its initial state when the electric field is removed. Therefore, it retains a relatively large remanent polarization of approximately 31.6 μC·cm when the electric field is zero. -2 When the composition is as in Example 1, the antiferroelectric P phase is stabilized, exhibiting a double hysteresis loop. However, although it exhibits a double hysteresis loop, it still retains a large remanent polarization of approximately 9 μC·cm. -2 This also hinders the improvement of energy storage performance. With further increases in doping content, in the composition of Example 2, large antiferroelectric domains are broken into nanoscale microdomains. This significantly reduces the domain flipping barrier, allowing them to quickly return to their initial state under a continuous electric field. This results in almost negligible remanent polarization, approximately 0.8 μC·cm⁻¹. -2 With further increases in doping content, although compositions 3 and 4 exhibit relatively small residual polarization, their maximum polarization is also small, which is detrimental to energy storage. The energy storage density and efficiency calculated according to the formula are shown in Table 2. With increasing doping content, the breakdown electric field of the NN-based ceramic first increases and then decreases; when composition is Example 2, the breakdown electric field is 467 kV·cm. -1 Achieving 5.1 J·cm⁻¹ under an electric field. -3 The recyclable energy density and energy storage efficiency of 94% demonstrate that the designed NN-based ceramic can achieve high energy storage performance and is expected to be used in advanced energy storage systems. Simultaneously, it maintains a high dielectric constant of 950 and a low dielectric loss of 0.004.

[0043] (4) Dielectric property analysis Figure 7 The dielectric constant and dielectric loss plots of the ceramic sample of Comparative Example 1 are shown from room temperature to 500 °C and from 1 k to 1000 kHz. It is well known that NN ceramics undergo very complex phase transitions during cooling from high temperatures to room temperature due to the tilt of the oxygen octahedron and the displacement of the central niobium ion. During the cooling process, NN roughly undergoes the following sequence: paraelectric cubic phase U (Pm3m). Paraelectric four-phase T2 (P4 / mbm) Paraelectro-orthogonal phase T1 (Ccmm) Paraelectro-orthogonal phase S (Pnmm) Antiferroelectric orthorhombic phase R (Pbnm) Antiferroelectric orthorhombic P (Pbcm) Ferroelectric trigonal phase N (R3c). As can be seen from the dielectric spectrum, the dielectric anomaly peak at approximately 390 °C is the transition peak from the antiferroelectric P phase to the antiferroelectric R phase. Figure 6 (In the figure, a, b, c, and d correspond to Examples 1, 2, 3, and 4 in sequence.) These are the dielectric temperature spectra of Examples 1-4 at -150℃ to 300℃ and 1 k to 1000 kHz. It can be seen that when the composition is that of Example 1, the antiferroelectric P phase is still maintained at room temperature. A prominent dielectric peak is clearly observed at approximately 160℃, which corresponds to the transition temperature from the antiferroelectric P phase to the antiferroelectric R phase. This further proves that the antiferroelectric P phase is stabilized, which corresponds to the hysteresis loop result. With further increases in doping composition, as shown in Examples 2-4, the sharp phase transition peak disappears, and a diffuse peak appears, indicating that the system is in a relaxed state. Furthermore, with increasing doping content, the dielectric constant at room temperature gradually decreases from 950 to 464, which also corresponds to a gradual decrease in polarization intensity under the same electric field with increasing doping content, consistent with the hysteresis loop result.

[0044] (5) TEM analysis TEM images of the ceramics in Example 2 and Comparative Example 1 are as follows: Figure 8 , Figure 9 As shown, for the composition of Comparative Example 1, it is evident that it has a domain size of approximately 500 nm. It is precisely this large antiferroelectric domain that results in a large remanent polarization, which is detrimental to improving energy storage performance. In contrast, no large domain structure was observed for the composition of Example 2. Instead, a large number of nanodomains are present in this ceramic sample, allowing it to rapidly flip when an electric field is applied / released, thereby maintaining a large maximum polarization while possessing near-zero remanent polarization.

[0045] In this embodiment, (1-) was prepared using a solid-state reaction method. x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 O3( x= A Bi(Ni) 0.05, 0.10, 0.15, and 0.20% Bi-NiO2 ceramic, labeled NN-BM5, was analyzed for its crystal structure, microstructure, dielectric properties, and energy storage performance, revealing the formation mechanism of its high energy density and efficiency. The results show that the grain size first decreases and then increases with increasing doping content. Furthermore, Bi(NiO2) 0.05, 0.10, 0.15, and 0.20% Bi-NiO2 ceramic was also analyzed. 0.2Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 The introduction of O3 significantly improves the energy storage performance of the material; at room temperature, with a doping concentration of 0.10 mol, the energy storage density is 5.1 J·cm⁻¹. -3 With an energy storage efficiency of 94.0%, a dielectric constant (ε') of 950 at 1 kHz, and a dielectric loss (tan δ) of 0.004, it is a promising candidate material for dielectric capacitors.

[0046] In summary, this invention successfully prepared NaNbO3-based ceramic materials with high energy storage density and efficiency. Through detailed studies and performance tests on different embodiments and comparative examples, including XRD analysis, SEM analysis, ferroelectric property analysis, dielectric property analysis, and TEM analysis, the influence of doping elements and their contents on the performance of NaNbO3-based ceramics was comprehensively and thoroughly investigated.

[0047] XRD analysis shows that the crystal structure of the ceramic changes with the doping content. 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 When O3 enters NaNbO3 ceramics beyond the solid solubility, a second phase will appear, and doping will cause the main peak to shift to a lower angle, reflecting the change in lattice spacing.

[0048] SEM analysis showed that the undoped ceramic samples had large and square grains. As the doping content increased, the grain size first decreased and then increased. All ceramics had a dense structure without pores. Some samples had second-phase particles attached to their surface, which is consistent with the XRD results.

[0049] Ferroelectric performance analysis shows that pure NN has an irreversible hysteresis loop and large residual polarization, which is not conducive to energy storage. As the doping content increases, the antiferroelectric P phase is stabilized, the large antiferroelectric domains are broken into nanoscale microregions, and the residual polarization is reduced. When the composition is as in Example 2, high recyclable energy density and energy storage efficiency can be achieved.

[0050] Dielectric property analysis revealed that NN ceramics undergo complex phase transitions during cooling. Doping affects the phase transition peaks. As the doping content increases, the dielectric constant gradually decreases at room temperature, which is consistent with the hysteresis loop results.

[0051] TEM analysis comparing Example 2 and Comparative Example 1 further confirmed that large antiferroelectric domains lead to large residual polarization, while nanodomain structures help to maintain near-zero residual polarization while maintaining large maximum polarization.

[0052] Based on the comprehensive performance test results, the NaNbO3-based ceramic material prepared by this invention exhibits excellent energy storage performance and is expected to be widely used in advanced energy storage systems. It provides new material selection and technical support for the development of related fields and has important scientific research value and practical application prospects.

[0053] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A NaNbO3-based ceramic material with high energy storage density and efficiency, characterized in that, The chemical formula of the NaNbO3-based ceramic material is: (1- x NaNbO3- x Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 O3, of which x for Bi(Ni 0.2 Mg 0.2 Zr 0.1 Ta 0.2 Hf 0.2 The molar percentage of O3; x The value range is 0 to 0.

20.

2. The NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 1, characterized in that, The x The values ​​include: 0, 0.05, 0.10, 0.15, and 0.

20.

3. The NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 2, characterized in that, The x When the value is 0.10, the energy storage density of the NaNbO3-based ceramic material is greater than 5 J·cm⁻¹. -3 Its energy storage efficiency is higher than 93%.

4. A method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency, characterized in that, The preparation method is used to prepare the NaNbO3-based ceramic material according to any one of claims 1 to 3, and the preparation method includes the following steps: Step S1: After mixing Na2CO3, Nb2O5, Bi2O3, NiO, MgO, ZrO2, Ta2O5, and HfO2, add zirconium oxide microspheres and alcohol, stir, and dry to obtain a mixed powder. Step S2: The mixed powder obtained in step S1 is ball-milled after pre-calcination and then dried again; Step S3: Press the powder obtained from drying in step S2 into sheets; Step S4: The pressed sheet obtained in step S3 is sintered to obtain NaNbO3-based ceramic.

5. The method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 4, characterized in that, The stirring speed in step S1 is 280–320 r·min. -1 .

6. The method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 4, characterized in that, In step S2, the pre-firing temperature is 820–880°C, and the pre-firing time is 3–5 hours.

7. The method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 4, characterized in that, In step S3, the tablets are pressed and formed under a cold isostatic pressure of 190–210 MPa.

8. The method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 4, characterized in that, The sheet pressed in step S3 is a circular sheet with a diameter of 9-15 mm and a thickness of 0.5-1.5 mm.

9. The method for preparing a NaNbO3-based ceramic material with high energy storage density and efficiency according to claim 4, characterized in that, In step S4, the sintering temperature is 1170–1230 °C, and the sintering time is 3–5 h.

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