A ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride, its preparation method and application

Abstract

This invention discloses a ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride, its preparation method, and its application. In the preparation process, methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate, and barium acetate are uniformly dispersed, and then polyvinylpyrrolidone is added and mixed uniformly to obtain solution A. Hexagonal boron nitride is then uniformly dispersed with ethanol and polyvinylpyrrolidone to obtain solution B. Solutions A and B are coaxially electrospun and then dried to obtain composite fibers. The composite fibers are calcined at 1000–1200℃ for 2.5–3.5 h, and then ground into powder to obtain the ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride. The coaxial electrospinning method can improve the energy storage density, efficiency, and charge / discharge efficiency of polymer composite film capacitors under high-temperature conditions.

Description

Technical Field

[0001] This invention belongs to the field of dielectric energy storage, specifically a ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride, its preparation method, and its application. Background Technology

[0002] Dielectric capacitors offer high power density due to their rapid charge and discharge rates. Polymer-based dielectric capacitors are widely used in power transmission, hybrid power systems, and other fields. Today, dielectric capacitors are indispensable in many areas, including integrated circuits, wind power generation, and electric vehicles.

[0003] Biaxially oriented polypropylene (BOPP), the most widely used polymer composite film capacitor, is currently used in power inverters for electric vehicles to control and convert the direct current (DC) from the battery into the alternating current (AC) required to drive the motor. However, its efficiency drops significantly at excessively high temperatures, falling far short of the growing demands for energy storage and conversion under extreme conditions, typically found in transportation, aerospace propulsion systems, and microelectronics. BOPP can only operate below 105°C because conductivity losses increase exponentially with rising temperature, and breakdown strength decreases sharply.

[0004] Therefore, with the development of the power electronics field, there is now an urgent need for dielectric capacitor films that can achieve high working efficiency under high temperature conditions. Summary of the Invention

[0005] To address the problem that polymer composite film capacitors in existing technologies cannot withstand high temperatures, this invention provides a ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride, along with its preparation method and applications. The material is prepared using a coaxial electrospinning method, which can improve the energy storage density, efficiency, and charge / discharge efficiency of polymer composite film capacitors under high-temperature conditions.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a composite nanosheet structure ceramic material with barium titanate fiber surface coated with hexagonal boron nitride includes the following steps:

[0008] S1, methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate and barium acetate are dispersed evenly, and then polyvinylpyrrolidone is added and mixed evenly. The ratio of methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate, barium acetate and polyvinylpyrrolidone is 9.37ml:3.57ml:2.8ml:0.86ml:1.157ml:0.86g:0.8g, to obtain solution A;

[0009] Hexagonal boron nitride, ethanol, and polyvinylpyrrolidone were dispersed evenly in a ratio of 0.4 g: 8.5 ml: 0.8 g to obtain solution B.

[0010] S2, solutions A and B are coaxially electrospun under an injection rate of 1.5–2.5 ml / h and an electric field of 1.2–1.8 kV / cm, and then dried to obtain composite fibers;

[0011] S3. The composite fibers are calcined at 1000-1200℃ for 2.5-3.5 hours and then ground into powder to obtain a ceramic material with a composite nanosheet structure of barium titanate fibers coated with hexagonal boron nitride.

[0012] Preferably, in step S1, methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate and barium acetate are first stirred at 45-55°C and 500-700 rpm for 1.5-2.5 hours, and then polyvinylpyrrolidone is added and stirred for 6-7 hours to obtain solution A.

[0013] Preferably, in step S1, hexagonal boron nitride is first dispersed in ethanol, then polyvinylpyrrolidone is added and sonicated for 0.5–1 h, stirred at 500–700 rpm at room temperature for 1.5–2.5 h, and finally sonicated for 0.5–1 h to form solution B.

[0014] Preferably, the humidity of S2 during coaxial electrospinning is 65%–75%, and the temperature is 30–40°C.

[0015] Preferably, the spinning distance of S2 during coaxial electrospinning is 12-18 cm.

[0016] Preferably, the drying described in S2 is carried out at 75-85°C for 4-5 hours.

[0017] Preferably, in step S3, the composite fiber is first heated to 1000-1200°C at a heating rate of 2-4°C / min, and then calcined.

[0018] A ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride, obtained by the preparation method of the composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride as described in any one of the above.

[0019] A method for preparing a polymer composite film involves preparing a dispersion of a ceramic material with a composite nanosheet structure of hexagonal boron nitride coated on the surface of barium titanate fibers and a polymer, and then obtaining the polymer composite film by a casting method. The polymer is polyetherimide, polyimide, polyvinylidene fluoride, or polyvinylidene fluoride-hexafluoropropylene.

[0020] A polymer composite film obtained by the aforementioned method for preparing polymer composite films.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] This invention discloses a method for preparing a ceramic material with a composite nanosheet structure of barium titanate fibers coated with hexagonal boron nitride. By controlling the flow rates and voltages of solutions A and B, a coaxial fiber structure can be formed during the spinning process. The composite fibers are then calcined at high temperature for 2.5–3.5 hours to obtain the ceramic material with the composite nanosheet structure of barium titanate fibers coated with hexagonal boron nitride. This method has significant reference value and implications for the future development of fiber-coated ceramic materials. The BaTiO3 fibers are approximately 300–500 nm long and 50–100 nm in diameter, while the h-BN nanosheets are approximately 25 nm in diameter. The h-BN nanosheets have high thermal conductivity, effectively absorbing and conducting heat, which helps to reduce the temperature of electronic devices and improve their stability and performance. Barium titanate nanofibers possess piezoelectric and dielectric properties; by coating them with h-BN nanosheets, the electrical properties of the barium titanate nanofibers can be further optimized, increasing the piezoelectric response and dielectric constant, thereby improving the performance of electronic devices.

[0023] The ceramic material of this invention has strong thermal stability and strong insulation properties. When it is doped into the polymer matrix, it can improve the dielectric constant and breakdown field strength of the polymer composite film, thereby improving its dielectric energy storage performance. At the same time, it can improve the energy storage density and efficiency of the polymer composite film under high temperature conditions, resulting in ultra-high energy storage density and excellent charge-discharge performance. Attached Figure Description

[0024] Figure 1 This is a morphology diagram of the BaTiO3 fiber coating in Example 1 of the present invention;

[0025] Figure 2 This is a morphological image of BaTiO3 fibers before coating in Example 1 of the present invention;

[0026] Figure 3 This is the XRD pattern of BaTiO3 fibers in Example 1 of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0028] This invention utilizes coaxial spinning to prepare a ceramic material with a composite nanosheet structure of BaTiO3 fibers coated with hexagonal boron nitride. This material can be used to improve the energy storage density and efficiency of polymer composite films under high-temperature conditions. The preparation method is as follows:

[0029] Step (1) 9.37 ml of methanol, 3.57 ml of propionic acid, 2.8 ml of acetic acid, 0.86 ml of acetylacetone, 1.157 ml of tetrabutyl titanate and 0.86 g of barium acetate are stirred at 45-55°C and 500-700 rpm for 1.5-2.5 h. Then 0.8 g of PVP is added and stirred for 6-7 h. 0.8 g of PVP is used to increase the viscosity of the solution, thereby forming solution A, which is the spinning solution for BaTiO3 fibers.

[0030] Then disperse 0.4g of hexagonal boron nitride (h-BN) in 8.5ml of ethanol, add 0.8g of PVP, sonicate for 0.5-1h, stir at 500-700rpm at room temperature for 1.5-2.5h, and sonicate again for 0.5-1h to form solution B.

[0031] Step (2) Place solutions A and B into two different injection points a and b for coaxial electrospinning. Set the injection speed to 1.5-2.5 ml / h, control the spinning humidity to 65%-75%, the temperature to 30-40℃, the spinning distance to 12-18 cm, and the electric field to 1.2-1.8 kV / cm.

[0032] Step (3) Place the spun sample in a drying oven and dry it at 75-85℃ for 4-5 hours. Then, heat it at a heating rate of 2-4℃ / min and calcine it in a muffle furnace at 1000-1200℃ for 2.5-3.5 hours. Grind the calcined ceramic powder into powder using a mortar and pestle.

[0033] Example 1

[0034] A ceramic material with a composite nanosheet structure of BaTiO3 fibers coated with hexagonal boron nitride was prepared by coaxial spinning to improve the energy storage density and efficiency of polymer composite films under high-temperature conditions. This material was then doped into polyetherimide (PEI). The preparation method includes the following steps:

[0035] (1) 9.37 ml of methanol, 3.57 ml of propionic acid, 2.8 ml of acetic acid, 0.86 ml of acetylacetone, 1.157 ml of tetrabutyl titanate, and 0.86 g of barium acetate were stirred at 600 rpm for two hours at 50 °C. Then, 0.8 g of polyvinylpyrrolidone (PVP) was added and stirred for 6 hours to obtain solution A. 0.4 g of h-BN nanosheets were dissolved in 8.5 ml of ethanol, and 0.8 g of PVP was added. The mixture was sonicated for 1 hour, stirred at 600 rpm for 2 hours at room temperature, and sonicated for 1 hour to obtain solution B.

[0036] (2) Place solutions A and B in an electrospinning machine for coaxial electrospinning. Solution A is placed in injection a and solution B is placed in injection b. During spinning, the injection speed is set to 2 ml / h, the spinning humidity is controlled at 70%, the temperature is 30℃, the spinning distance is set to 15 cm, and the electric field is 1.5 kV / cm.

[0037] (3) The sample obtained by spinning is dried at 80℃ for 5 hours and then calcined at 1000℃ with a heating rate of 2℃ / min and a calcination holding time of 3 hours.

[0038] (4) The calcined sample was ground to obtain a BaTiO3 fiber surface coated with BN nanosheet nanocomposite material.

[0039] (5) To compare with BaTiO3 fibers coated with hexagonal boron nitride, the microstructure of uncoated BaTiO3 fibers was also analyzed (i.e., electrospinning was performed using only solution A in injection a, with subsequent steps remaining unchanged), as follows: Figure 2 and Figure 1 As shown, XRD patterns of pure BaTiO3 fibers were performed. Figure 3 As shown in the figure. The XRD pattern shows that its fiber structure is clear and there are no obvious impurities. The morphology of the BaTiO3 fiber-coated BN nanosheet nanocomposite is as follows. Figure 2 As shown.

[0040] (6) Take 0.133g of BaTiO3 fiber surface coated with BN nanosheet nanocomposite material and polyetherimide (PEI) and dissolve it in 10ml of 1-methyl-2-pyrrolidone (NMP). Stir it at 50℃ for 24h and sonicate it for 1h to obtain mixture C.

[0041] Mixed solution C was cast using a casting method, with the casting machine temperature set to 190 degrees Celsius and the doctor blade height set to 11 μm. To ensure sufficient evaporation of the solvent NMP, the mixture was vacuum dried for 30 min and then dried at 80°C for 12 h to obtain a composite film of ceramic material with a single-layer PEI composite BaTiO3 fiber surface coated with h-BN nanosheet structure.

[0042] (7) The uniform distribution of fiber-coated structure in PEI can be determined by SEM film cross-sectional structure.

[0043] (8) By testing the dielectric frequency, the composite thin film was obtained from a test of 10. 3 Hz to 10 6The dielectric constant and dielectric loss of pure PEI film are approximately 3.5 and 0.01, respectively. The dielectric constant of 10% BaTiO3@h-BN / PEI composite film is expected to be around 20 and the dielectric loss is expected to be around 0.02-0.04.

[0044] (9) Ferroelectric testing was conducted on a composite film of a ceramic material with a monolayer PEI composite BaTiO3 fiber surface coated with h-BN nanosheets. The highest breakdown field strength E of the 10% BaTiO3@h-BN / PEI composite film was expected to be... b It can reach 5000 kV / cm, and the energy storage density can reach 6 J / cm. 3 above.

[0045] (10) When the temperature is increased from room temperature to 200℃, its dielectric constant is expected to remain relatively stable with no significant change, while the dielectric loss increases slightly. The high thermal conductivity of h-BN can improve the heat dissipation capacity of the composite film, thereby greatly reducing the leakage current of the dielectric composite material at high temperatures and improving its breakdown strength.

[0046] Example 2

[0047] A ceramic material with a composite nanosheet structure of BaTiO3 fibers coated with hexagonal boron nitride was prepared by coaxial spinning to improve the energy storage density and efficiency of polymer composite films under high-temperature conditions. This material was then doped into polyimide (PI). The preparation method includes the following steps:

[0048] (1) 9.37 ml of methanol, 3.57 ml of propionic acid, 2.8 ml of acetic acid, 0.86 ml of acetylacetone, 1.157 ml of tetrabutyl titanate and 0.86 g of barium acetate were stirred at 600 rpm for two hours at 50 °C. Then 0.78 g of polyvinylpyrrolidone (PVP) was added and stirred for 6 hours to obtain solution A.

[0049] (2) Dissolve 0.4g h-BN nanosheets in 8.5ml ethanol, add 0.8g PVP, sonicate for 0.5h, stir at 600rpm for 2h at room temperature, sonicate for 0.5h to obtain solution B.

[0050] (3) Place solutions A and B in an electrospinning machine for coaxial electrospinning. Solution A is placed in injection a and solution B is placed in injection b. During spinning, the injection speed is set to 2 ml / h, the spinning humidity is controlled at 70%, the temperature is 40℃, the spinning distance is set to 15 cm, and the electric field is 1.5 kV / cm.

[0051] (4) The spun sample was dried at 80℃ for 5 hours, and then calcined at 1000℃ with a heating rate of 2℃ / min for 3 hours.

[0052] (5) The calcined sample was ground to obtain a BaTiO3 fiber surface coated with BN nanosheet nanocomposite material.

[0053] (6) 4,4′-diaminodiphenyl ether (ODA) was stirred thoroughly in the solvent N,N-dimethylformamide (DMF), and then pyromellitic anhydride (PMDA) was slowly added to the solution. The mixture was stirred for 12 hours to form the precursor of PI (PAA). BN nanosheet nanocomposite material coated on the surface of BaTiO3 fiber was added, and the mixture was stirred and sonicated to obtain the mixture D.

[0054] (7) The mixture D was cast into a polymer nanocomposite film by casting method. The height of the casting doctor blade was set to 12 μm and the casting temperature was set to 190 °C. In order to ensure that the solvent evaporates fully, vacuum drying was performed for 30 min and then dried at 80 °C for 12 h to obtain BaTiO3@h-BN / PI nanocomposite film.

[0055] (8) The uniformity of fiber-coated structural materials in PI can be determined by the cross-sectional structure of the thin film using SEM.

[0056] (9) The composite thin film was obtained through dielectric frequency testing. 3 Hz to 10 6 The dielectric constant and dielectric loss of pure PI film are approximately 5, and the dielectric loss is approximately 0.01-0.02. It is estimated that the dielectric constant of 20% BaTiO3@h-BN / PEI composite film is approximately 40, and the dielectric loss is estimated to be approximately 0.02-0.05.

[0057] (11) Ferroelectric testing was conducted on a composite film of a ceramic material with a monolayer PI composite BaTiO3 fiber surface coated with h-BN nanosheets. The highest breakdown field strength E of the 20% BaTiO3@h-BN / PI composite film was expected to be obtained. b It can reach 2000 kV / cm, and the energy storage density can reach 5 J / cm³. 3 above.

[0058] (12) When the temperature is increased from room temperature to 200℃, the dielectric constant is expected to be relatively stable with no significant change, while the dielectric loss increases slightly.

Claims

1. A method for preparing a polymer composite film, characterized in that, A ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride was prepared into a dispersion with a polymer, and then the polymer composite film was obtained by casting. The polymer is polyetherimide, polyimide, polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene. The method for preparing the ceramic material with a composite nanosheet structure of barium titanate fiber coated with hexagonal boron nitride includes the following steps: S1, methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate and barium acetate are dispersed evenly, and then polyvinylpyrrolidone is added and mixed evenly. The ratio of methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate, barium acetate and polyvinylpyrrolidone is 9.37ml:3.57ml:2.8ml:0.86ml:1.157ml:0.86g:0.8g, to obtain solution A; Hexagonal boron nitride, ethanol, and polyvinylpyrrolidone were dispersed evenly in a ratio of 0.4 g: 8.5 ml: 0.8 g to obtain solution B. S2, solutions A and B are coaxially electrospun under an injection rate of 1.5~2.5 ml / h and an electric field of 1.2~1.8 kV / cm. The spinning distance during coaxial electrospinning is 12~18 cm, the humidity is 65%~75%, and the temperature is 30~40℃. After drying, composite fibers are obtained. S3. The composite fibers are calcined at 1000~1200℃ for 2.5~3.5h, and then ground into powder to obtain a ceramic material with a composite nanosheet structure of barium titanate fibers coated with hexagonal boron nitride.

2. The method for preparing the polymer composite film according to claim 1, characterized in that, S1 First, methanol, propionic acid, acetic acid, acetylacetone, tetrabutyl titanate and barium acetate are stirred at 45~55℃ and 500~700 rpm for 1.5~2.5h. Then, polyvinylpyrrolidone is added and stirred for 6~7h to obtain solution A.

3. The method for preparing the polymer composite film according to claim 1, characterized in that, S1 First, hexagonal boron nitride is dispersed in ethanol, then polyvinylpyrrolidone is added and sonicated for 0.5-1 h. The mixture is then stirred at 500-700 rpm at room temperature for 1.5-2.5 h, and finally sonicated for 0.5-1 h to form solution B.

4. The method for preparing the polymer composite film according to claim 1, characterized in that, The drying process described in S2 is carried out at 75~85℃ for 4~5 hours.

5. The method for preparing the polymer composite film according to claim 1, characterized in that, S3 first heats the composite fiber to 1000-1200℃ at a heating rate of 2-4℃ / min, and then calcines it.

6. A polymer composite film obtained by the preparation method of the polymer composite film according to any one of claims 1 to 5.

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