A Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency and its preparation method

Abstract

This invention discloses a Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency and its preparation method. The method includes: Step 1, mixing Na2CO3, K2CO3, BaCO3, SrCO3, CaCO3, Bi2O3, TiO2, Nb2O5 and SiO2 evenly to obtain mixture A; Step 2, adding mixture A into a crucible preheated to 1100-1300℃, then raising the temperature to 1450℃ and holding it at that temperature to completely melt mixture A. The process continues until no more bubbles are generated, resulting in a melt. This melt is then poured into a mold preheated to 200°C, and after molding, product B is obtained. Step 3: Product B is transferred to an annealing furnace preheated to 500–600°C and held at that temperature. After cooling in the furnace, a glass sample is obtained. Step 4: The glass sample is placed in a muffle furnace and heated from room temperature to 800–1000°C at a rate of 5°C / min, and held at that temperature to crystallize the glass sample. After cooling in the furnace, Ca2Nb2O7 glass-ceramic material is obtained. This invention not only has a simple preparation process, but also produces Ca2Nb2O7 glass-ceramic with high breakdown strength and high energy storage efficiency.

Description

Technical Field

[0001] This invention relates to glass-ceramic materials, specifically a Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency and its preparation method. Background Technology

[0002] With the popularization and development of new energy electric vehicles, energy storage materials have become a research hotspot in the field of new energy materials. They are mainly used in batteries, electrochemical capacitors, and dielectric capacitors in electrical products. As electrical products gradually develop towards lightweighting, miniaturization, and integration, improving energy efficiency and developing green new energy sources, designing dielectric capacitors with high energy storage performance has become an urgent need. Currently, dielectric capacitors on the market are mainly divided into ceramic, polymer, and composite materials. Among them, ceramic dielectric capacitors have received widespread attention due to their high power density, strong temperature stability, and excellent fatigue resistance. However, the presence of numerous pores reduces their density, resulting in lower breakdown strength and energy storage density. The low dielectric constant and poor thermal stability of polymers or polymer-based composite materials also limit their widespread application. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency and its preparation method. The preparation process is simple, and the prepared Ca2Nb2O7 glass-ceramic has high breakdown strength and high energy storage efficiency.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for preparing a Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency includes the following steps:

[0006] Step 1: Mix 27.8–30 mol Na₂CO₃, 5.2–6.8 mol K₂CO₃, 5.2–8.7 mol BaCO₃, 3–7 mol SrCO₃, 3–7 mol CaCO₃, 3–7 mol Bi₂O₃, 15–35 mol TiO₂, 26–34 mol Nb₂O₅, and 11.3–14.8 mol SiO₂ until homogeneous to obtain mixture A;

[0007] Step 2: Add mixture A to a crucible that has been preheated to 1100-1300°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, to obtain a melt. Then pour the melt into a mold that has been preheated to 200°C, and after molding, obtain product B.

[0008] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 500-600°C and hold it at that temperature. After cooling in the furnace, a glass sample is obtained.

[0009] Step 4: Place the glass sample into a muffle furnace and heat it from room temperature to 800℃~1000℃ at a heating rate of 5℃ / min and hold it at that temperature to crystallize the glass sample. After cooling with the furnace, the Ca2Nb2O7 glass ceramic material is obtained.

[0010] Furthermore, the molar ratio of Na2CO3, K2CO3, BaCO3, SrCO3, CaCO3, Bi2O3, TiO2, Nb2O5 and SiO2 in step 1 is 29:6:6.95:5:5:5:25:30:13.05.

[0011] Furthermore, the mold in step 2 is made of pure copper.

[0012] Furthermore, the heat preservation time in step 3 is 2 to 8 hours.

[0013] Furthermore, in step 4, the temperature at which the glass sample is crystallized is 900°C.

[0014] Furthermore, the heat preservation time in step 4 is 1 to 4 hours.

[0015] A Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency includes a crystalline phase and a glass phase, wherein the crystalline phase is Ca2Nb2O7 and the glass phase is silicon dioxide.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] This invention employs a melt-process method to prepare Ca2Nb2O7 glass-ceramic materials. This method is not only simple, with a straightforward process and short production cycle, making it suitable for industrial production, but also allows for the adjustment of the Ca2Nb2O7 glass-ceramic shape by changing molds of different shapes to meet actual production needs. Furthermore, the Ca2Nb2O7 glass-ceramic exhibits small grain size, high density, and uniform distribution within the glass matrix, achieving an energy storage efficiency η = 99.6% and a breakdown strength E... b =480kV / cm. However, most traditional ceramic energy storage efficiencies are low, with a maximum of 80%, and a breakdown strength not exceeding 200-300kV / cm. This sufficiently demonstrates that the Ca2Nb2O7 glass-ceramic prepared in this invention possesses both high energy storage efficiency and high breakdown field strength, and is expected to replace traditional ceramic materials, becoming one of the next-generation candidate energy storage materials. Attached Figure Description

[0018] Figure 1 XRD pattern of Ca2Nb2O7 glass-ceramic material prepared in Example 1 of this invention;

[0019] Figure 2 : The unipolar PE curve of the Ca2Nb2O7 glass-ceramic material prepared in Example 1 of this invention;

[0020] Figure 3 SEM image of the Ca2Nb2O7 glass-ceramic material prepared in Example 1 of this invention. Detailed Implementation

[0021] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0022] Example 1

[0023] Step 1: Mix 29 mol Na2CO3, 6 mol K2CO3, 6.95 mol BaCO3, 5 mol SrCO3, 5 mol CaCO3, 5 mol Bi2O3, 25 mol TiO2, 30 mol Nb2O5 and 13.05 mol SiO2 until homogeneous to obtain mixture A;

[0024] Step 2: Add mixture A to a crucible preheated to 1250°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, thus obtaining a melt. Then pour the melt into a copper mold preheated to 200°C, and after molding, obtain product B.

[0025] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 500°C and hold it at that temperature for 5 hours to eliminate internal stress. After cooling in the furnace, a glass sample is obtained.

[0026] Step 4: Place the glass sample into a muffle furnace, heat it from room temperature to 900℃ at a heating rate of 5℃ / min and hold it at that temperature for 1 hour. After cooling with the furnace, the Ca2Nb2O7 glass-ceramic material is obtained.

[0027] A small amount of the Ca2Nb2O7 glass-ceramic material prepared in Example 1 was ground into powder and subjected to XRD diffraction analysis. The results are as follows: Figure 1 As shown, the diffraction peaks correspond perfectly to the PDF card of Ca2Nb2O7, and no other impurity phases are precipitated, indicating that Ca2Nb2O7 glass-ceramic material has been successfully prepared.

[0028] The Ca2Nb2O7 glass-ceramic material prepared in Example 1 was cut into thin slices with a thickness of 0.1–0.2 mm using a wire cutting machine. The slices were first polished and ultrasonically cleaned, and then gold electrodes were uniformly sprayed onto both sides of the slices to obtain the glass-ceramic sample to be tested. The results are as follows: Figure 2 As shown, the Ca2Nb2O7 glass-ceramic sample exhibits a thin hysteresis loop, and the breakdown strength E...b =480kV / cm, actual energy storage density W rec =1.21J / cm 3 The energy storage efficiency η = 99.6%.

[0029] from Figure 3 As can be seen, in the Ca2Nb2O7 glass-ceramic material prepared in Example 1, Ca2Nb2O7 crystals are uniformly precipitated from the glass matrix, with fine and uniformly distributed grains, providing a good physical basis for breakdown strength.

[0030] Example 2

[0031] Step 1: Mix 30 mol Na2CO3, 6.8 mol K2CO3, 5.2 mol BaCO3, 3 mol SrCO3, 3 mol CaCO3, 3 mol Bi2O3, 15 mol TiO2, 34 mol Nb2O5 and 14.8 mol SiO2 until homogeneous to obtain mixture A;

[0032] Step 2: Add mixture A to a crucible preheated to 1100°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, thus obtaining a melt. Then pour the melt into a copper mold preheated to 200°C, and after molding, obtain product B.

[0033] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 600°C and hold it at that temperature for 2 hours to eliminate internal stress. After cooling in the furnace, a glass sample is obtained.

[0034] Step 4: Place the glass sample into a muffle furnace, heat it from room temperature to 800℃ at a heating rate of 5℃ / min and hold it at that temperature for 4 hours. After cooling with the furnace, the Ca2Nb2O7 glass-ceramic material is obtained.

[0035] Example 3

[0036] Step 1: Mix 29.6 mol Na2CO3, 6.4 mol K2CO3, 6 mol BaCO3, 4 mol SrCO3, 4 mol CaCO3, 4 mol Bi2O3, 20 mol TiO2, 32 mol Nb2O5 and 13.9 mol SiO2 until homogeneous to obtain mixture A;

[0037] Step 2: Add mixture A to a crucible that has been preheated to 1300°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, thus obtaining a melt. Then pour the melt into a copper mold that has been preheated to 200°C, and after molding, obtain product B.

[0038] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 550°C and hold it at that temperature for 8 hours to eliminate internal stress. After cooling in the furnace, a glass sample is obtained.

[0039] Step 4: Place the glass sample into a muffle furnace, heat it from room temperature to 1000℃ at a heating rate of 5℃ / min and hold it at that temperature for 2 hours. After cooling with the furnace, the Ca2Nb2O7 glass-ceramic material is obtained.

[0040] Example 4

[0041] Step 1: Mix 28.4 mol Na2CO3, 5.6 mol K2CO3, 7.8 mol BaCO3, 6 mol SrCO3, 6 mol CaCO3, 6 mol Bi2O3, 30 mol TiO2, 28 mol Nb2O5 and 12.2 mol SiO2 until homogeneous to obtain mixture A;

[0042] Step 2: Add mixture A to a crucible preheated to 1150°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, thus obtaining a melt. Then pour the melt into a copper mold preheated to 200°C, and after molding, obtain product B.

[0043] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 600°C and hold it at that temperature for 6 hours to eliminate internal stress. After cooling in the furnace, a glass sample is obtained.

[0044] Step 4: Place the glass sample into a muffle furnace, heat it from room temperature to 950℃ at a heating rate of 5℃ / min and hold it at that temperature for 3 hours. After cooling with the furnace, the Ca2Nb2O7 glass-ceramic material is obtained.

[0045] Example 5

[0046] Step 1: Mix 27.8 mol Na2CO3, 5.2 mol K2CO3, 8.7 mol BaCO3, 7 mol SrCO3, 7 mol CaCO3, 7 mol Bi2O3, 35 mol TiO2, 26 mol Nb2O5 and 11.3 mol SiO2 until homogeneous to obtain mixture A;

[0047] Step 2: Add mixture A to a crucible preheated to 1200°C, then raise the temperature to 1450°C and hold it until mixture A is completely melted and no bubbles are generated, thus obtaining a melt. Then pour the melt into a copper mold preheated to 200°C, and after molding, obtain product B.

[0048] Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 500°C and hold it at that temperature for 3 hours to eliminate internal stress. After cooling in the furnace, a glass sample is obtained.

[0049] Step 4: Place the glass sample into a muffle furnace, heat it from room temperature to 850℃ at a heating rate of 5℃ / min and hold it at that temperature for 4 hours. After cooling with the furnace, the Ca2Nb2O7 glass-ceramic material is obtained.

Claims

1. A method for preparing a Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency, characterized in that, Includes the following steps: Step 1: Mix 27.8~30 mol Na2CO3, 5.2~6.8 mol K2CO3, 5.2~8.7 mol BaCO3, 3~7 mol SrCO3, 3~7 mol CaCO3, 3~7 mol Bi2O3, 15~35 mol TiO2, 26~34 mol Nb2O5 and 11.3~14.8 mol SiO2 until homogeneous to obtain mixture A; Step 2: Add mixture A to a crucible that has been preheated to 1100~1300℃, then raise the temperature to 1450℃ and keep it there, so that mixture A is completely melted until no bubbles are generated, and a melt is obtained. Then pour the melt into a mold that has been preheated to 200℃, and after molding, product B is obtained. Step 3: Quickly transfer product B to an annealing furnace that has been preheated to 500~600℃ and hold it at that temperature. After cooling in the furnace, a glass sample is obtained. Step 4: Place the glass sample into a muffle furnace and heat it from room temperature to 800℃~1000℃ at a heating rate of 5℃ / min and hold it at that temperature to crystallize the glass sample. After cooling with the furnace, Ca2Nb2O7 glass ceramic material is obtained.

2. The method for preparing Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency according to claim 1, characterized in that, The molar ratio of Na2CO3, K2CO3, BaCO3, SrCO3, CaCO3, Bi2O3, TiO2, Nb2O5 and SiO2 in step 1 is 29:6:6.95:5:5:5:25:30:13.

05.

3. The method for preparing Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency according to claim 1, characterized in that, The mold used in step 2 is made of pure copper.

4. The method for preparing Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency according to claim 1, characterized in that, The heat preservation time in step 3 is 2 to 8 hours.

5. The method for preparing Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency according to claim 1, characterized in that, Step 4 involves crystallizing the glass sample at a temperature of 900°C.

6. The method for preparing Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency according to claim 1, characterized in that, The heat preservation time in step 4 is 1 to 4 hours.

7. A Ca2Nb2O7 glass-ceramic material with excellent energy storage efficiency prepared by the method according to any one of claims 1 to 6, characterized in that, It includes a crystalline phase and a glassy phase, with the crystalline phase being Ca2Nb2O7.

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