Preparation method and application of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite membrane

Abstract

The present invention provides a preparation method and application of a flexible hydroxy-modified BNT-CBZ-OH ceramic particle / polymer composite film, relating to the technical field of flexible energy storage capacitors. The preparation process of the composite film is as follows: First, a sodium bismuth titanate (BNT) seed template is textured; a highly oriented lead-free BNT-CBZ textured ceramic is prepared by using a solid-phase sintering and template grain growth technology; the surface of the ceramic particles is hydroxylated; a P(VDF-TrFE) transparent slurry is prepared and mixed and ball-milled with the hydroxylated ceramic powder; finally, the composite film is prepared by a casting film method. The energy storage capacitor prepared by using the composite film prepared by the present invention has good ductility and high output performance, and can be widely applied to fields such as electronic circuits, energy harvesting, smart grids, and pulsed power systems.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage capacitors, and particularly to a preparation method and application of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film. Background Art

[0002] Dielectric energy storage materials play an important role in modern technology, especially in the fields of flexible electronics and energy storage. However, traditional dielectric ceramic materials have many limitations. Conventional dielectric ceramics are hard and have a low breakdown electric field, which is the maximum tolerable electric field. This limits their flexible applications and also restricts their applications under high voltage conditions. On the other hand, although pure flexible polymer energy storage materials have good flexibility and processability, their output performance is low and it is difficult to meet the actual application requirements. Therefore, how to improve the output performance of dielectric energy storage materials while maintaining flexibility has become an urgent problem to be solved.

[0003] To solve the above problems, researchers have tried to combine traditional dielectric ceramics with flexible polymers to prepare composite materials. However, such composite materials still face many challenges in practical applications. First, there are large differences in physical and chemical properties between the organic polymer matrix and the inorganic ceramic filler, resulting in poor compatibility between the two. Nano-ceramic fillers with high surface energy are extremely prone to agglomeration in the polymer matrix, and then a large number of pores are formed inside the composite material, significantly reducing the breakdown electric field of the composite dielectric material. In addition, the low breakdown electric field of traditional energy storage ceramics further restricts their applications in the field of high voltage energy storage. These problems seriously restrict the performance improvement and practical applications of composite piezoelectric materials. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a preparation method and application of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film. By using template-textured ceramics to increase the breakdown field strength of energy storage ceramics, hydroxyl-modifying ceramic particles to improve their compatibility with polymers, etc., the breakdown field strength of the composite dielectric material is improved in many aspects. The prepared hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film is applied to energy storage capacitors, meeting flexible applications and high voltage occasions with high output performance.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0006] A preparation method of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film, the preparation method comprising the following steps:

[0007] S1. Prepare Bi 0.5 Na 0.5 TiO3 (BNT) template grains:

[0008] S1-1: Prepare a Bi4Ti3O 12 precursor using Bi2O3 and TiO2;

[0009] S1-2. Mix the Bi4Ti3O 12 precursor with TiO2 and Na2CO3, ball-mill the mixture, and then sinter it to obtain Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals;

[0010] S1-3. Mix the Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals with Na2CO3, ball-mill the mixture, and then sinter it. After removing Bi2O3 from the product, obtain Bi 0.5 Na 0.5 TiO3 template crystals, i.e., BNT seed templates;

[0011] S2. Template-textured BNT-CBZ ceramic powder: Weigh the raw materials according to the formula of 0.7(Bi 0.5 Na 0.5 )TiO3-0.3Ca 0.85 Bi 0.1 ZrO3, mix and ball-mill them, then heat up for pre-sintering, and then mix with BNT seed templates, ball-mill, and sinter to obtain BNT-CBZ textured ceramic powder;

[0012] S3. Surface hydroxylation of ceramic powder: Disperse the BNT-CBZ textured ceramic powder into hydrogen peroxide solution for surface hydroxylation treatment to obtain BNT-CBZ-OH ceramic particles;

[0013] S4. Preparation of ceramic particle / P(VDF-TrFE) mixed slurry: Dissolve P(VDF-TrFE) in N,N-dimethylformamide, and then add BNT-CBZ-OH ceramic particles to obtain ceramic particle / P(VDF-TrFE) mixed slurry;

[0014] S5. Tape casting: Cast the above-mentioned mixed slurry on a substrate in a tape casting machine and cure it to form a composite film.

[0015] Preferably, the specific process in step S1-1 is to mix Bi2O3 and TiO2 with a molar ratio of 2:3 into reaction powder, then add a mixed powder with the same mass as the reactant powder. After mixing, place it in a ball-milling tank, add ethanol, and ball-mill for 10 - 12 h at a ball-milling speed of 250 - 300 r / min. Take it out, dry it, and sieve it. Put it into a crucible, keep it warm at 1080 °C for 1 h, and then repeatedly rinse off the salt with deionized water to obtain Bi4Ti3O 12Precursor; and the mixed powder is obtained by mixing NaCl and KCl in a molar ratio of 1:1.

[0016] Preferably, the specific process in the step S1-2 is to mix the Bi4Ti3O 12 precursor with TiO2 and Na2CO3 in a molar ratio of 9:2:5 to obtain a reactant powder, add the mixed powder with the same mass as the reactant powder, ball mill for 10 - 12 h, take out, dry and sieve, put it in a crucible and keep it at 1080 °C for 1 h, and then repeatedly rinse with deionized water to remove the salt, to obtain Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals; wherein the mixed powder is obtained by mixing NaCl and KCl in a molar ratio of 1:1.

[0017] Preferably, the specific steps in the step S1-3 are to mix the Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals with Na2CO3 in a molar ratio of 4:3 to obtain a reaction powder, add the mixed powder with the same mass as the reactant powder, ball mill for 10 - 12 h, take out, dry and sieve, put it in a crucible and keep it at 1060 °C for 3 h, and then repeatedly rinse with deionized water to remove the salt, and use 6 mol / L HCl to remove the generated Bi2O3, to obtain Bi 0.5 Na 0.5 TiO3 template crystals; wherein the mixed powder is obtained by mixing NaCl and KCl in a molar ratio of 1:1.

[0018] Preferably, the raw materials selected in the step S2 are TiO2, Bi2O3, Na2CO3, CaO, ZrO2, the purity of each raw material is > 98%, and the raw materials are dried at 80 - 100 °C for more than 3 h before use.

[0019] Preferably, the specific steps in the step S2 are:

[0020] S2-1. Place the weighed raw materials in a nylon ball mill tank containing zirconia grinding balls, add absolute ethanol and ball mill for 10 - 24 h, and then heat up to 800 - 900 °C and pre-burn for 2 - 3 h to obtain a pre-burned powder;

[0021] S2-2. Mix the pre-burned powder and the BNT seed crystal template by ball milling in a mass ratio of 1 - 3:10 - 50, continue to ball mill for 10 - 20 h, and then dry and sieve through an 80-mesh sieve to obtain a mixed powder;

[0022] S2-3. Sinter the mixed powder at 1050 - 1150 °C for 2 - 3 h to obtain a BNT-CBZ textured ceramic powder.

[0023] Preferably, the specific operation of surface hydroxylation in step S3 is to disperse BNT-CBZ textured ceramic powder at a ratio of 1 g∶10 ml into a hydrogen peroxide solution with a concentration of 35%, and magnetically stir it at a rotation speed of 500-800 r / min at 80-100 °C for 3 h for sufficient reaction; after the reaction, centrifuge at a rotation speed of 3000 rpm for 8-10 minutes to obtain a precipitate; wash the precipitate with distilled water and ethanol and then keep it warm in a vacuum drying oven at 70-100 °C for 8-12 h to obtain BNT-CBZ-OH ceramic particles.

[0024] Preferably, the ratio of P(VDF-TrFE) powder dissolved in N,N-dimethylformamide in step S4 is 1 g∶20 ml; and the content of BNT-CBZ-OH ceramic particles in the mixed slurry accounts for 2 wt%-10 wt%. After mixing, perform high-energy ball milling at a rotation speed of 300-500 rmp / min for 20-30 min and then defoam in a vacuum mixer for 3 h.

[0025] Preferably, the distance between the doctor blade and the casting base tape in step S5 is set to 20-100 μm, the traveling speed of the doctor blade is 20-50 cm / min, and it is dried into a thick film at 40-80 °C. Then, it is heated to 50-90 °C in a vacuum drying oven and cured for 5-10 h. Subsequently, the temperature is raised to 130 °C and kept warm for 2-3 h to obtain a BNT-CBZ-OH / polymer composite film.

[0026] The above composite film is applied to the preparation of energy storage capacitors. The application method is to use an ITO transparent conductive film as the substrate, cast a BNT-CBZ-OH / polymer composite film on the ITO transparent conductive film, and then sputter a gold electrode on the top mask.

[0027] The present invention provides a preparation method and application of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film. Compared with the prior art, the advantages are as follows:

[0028] The present invention selects 0.7(Bi 0.5 Na 0.5 )TiO3-0.3Ca 0.85 Bi 0.1ZrO3 energy storage ceramic formula, prepare BNT template and texture BNT-CBZ ceramic powder. The lattice matching degree between the BNT template and BNT-CBZ ceramic is consistent, which is one of the ideal templates for texture BNT-based ceramics and can induce grain orientation growth. After introducing hydroxyl groups on the surface of BNT-CBZ ceramic powder, hydrogen bonds are formed between the hydroxyl groups and fluorine atoms in the PVDF molecules. This effect greatly improves the dispersion effect of nano-fillers in the polymer matrix and significantly reduces defects such as pores inside the composite material. At the same time, the BNT-CBZ ceramic particles and P(VDF-TrFE) polymer are mixed and ball-milled. During the high-energy ball-milling process, the "drag effect" generated promotes the transformation of the α crystal phase in the PVDF polymer into the β crystal phase with higher piezoelectric performance, so that the prepared slurry exhibits more excellent piezoelectric performance. Using the tape-casting process can make the arrangement of BNT-CBZ ceramic grains more regular, thereby optimizing its piezoelectric performance. Finally, this material exhibits a high breakdown field strength, and the energy storage density reaches 13.8 J / cm 3 , the breakdown electric field reaches 480 kV / mm. The energy storage capacitor prepared by using the composite film prepared by the present invention has good ductility and high output performance, and can be widely used in fields such as electronic circuits, energy harvesting, smart grids, and pulse power systems. Description of the Drawings

[0029] Figure 1 It is the surface grain morphology characteristics of the BNT-CBZ textured ceramic in Examples 3, 4 and 5 of the present invention;

[0030] Figure 2 It is the structural schematic diagram of the energy storage capacitor of the polymer composite film of the present invention, and the enlarged view is the surface morphology characteristics of the BNT-CBZ-OH / polymer composite film;

[0031] Figure 3 It is the photo of the polymer composite film prepared in Example 3 of the present invention;

[0032] Figure 4 It is the dielectric spectrum diagram of the energy storage capacitor of the polymer composite film prepared in each example of the present invention, wherein Figure (a) is the dielectric constant spectrum and Figure (b) is the dielectric loss spectrum;

[0033] Figure 5 It is the comparison of the breakdown electric fields of the energy storage capacitors of the polymer composite films prepared in each example of the present invention;

[0034] Figure 6 It is the comparison of the single-pole electric hysteresis loops of the energy storage capacitors of the polymer composite films prepared in each example of the present invention;

[0035] Figure 7 It is the comparison of the effective energy storage densities of the energy storage capacitors of the polymer composite films prepared in each example of the present invention;

[0036] Figure 2 Among them: 1. Sputtered gold electrode; 2. BNT-CBZ-OH / polymer composite film; 3. Bottom ITO transparent conductive film. Specific implementation manners

[0037] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] All the following raw materials are purchased from Shanghai Macklin Biochemical Co., Ltd. and Sinopharm Chemical Reagent Co., Ltd., and the purity requirement is above analytical pure (content > 98%).

[0039] Example 1:

[0040] Preparation of P(VDF-TrFE) polymer film

[0041] (1) Preparation of P(VDF-TrFE) slurry

[0042] Dissolve 2 grams of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) powder in 40 ml of N,N-dimethylformamide (DMF), and magnetically stir at 50 °C for 4 h until completely dissolved to obtain a transparent solution. Subsequently, put the solution into a vacuum mixer for degassing for 3 h to ensure that there are no bubbles in the solution, and obtain P(VDF-TrFE) slurry.

[0043] (2) Casting film

[0044] Using the ITO transparent conductive film as the substrate, cast the P(VDF-TrFE) slurry in a casting machine. The distance between the doctor blade and the casting belt is set to 40 μm, and the traveling speed of the doctor blade is 30 cm / min. Finally, cast the uniform slurry into a film strip with a thickness of 40 μm, and dry it into a thick film at 60 °C; then heat the sample in a vacuum drying oven, select the temperature to be 80 °C, heat for 10 h for curing, and then raise the temperature to 130 °C and keep it warm for 2 h to obtain the P(VDF-TrFE) polymer film. Cut the composite film into a shape of 15 mm × 15 mm, with a thickness of about 15 μm, and sputter a gold electrode with a diameter of 2 mm and a thickness of 40 nm on the top mask to obtain a polymer composite film energy storage capacitor.

[0045] Example 2:

[0046] Preparation of BNT-CBZ ceramic particle / polymer composite film:

[0047] 1. Preparation of BNT-CBZ ceramic powder

[0048] The BNT-CBZ textured ceramic is prepared by the traditional solid-phase sintering method, and the steps are as follows:

[0049] (1) Select raw materials TiO2, Bi2O3, Na2CO3, CaO, ZrO2 (the purity of all raw materials is >98%); dry the raw material flour at 100°C for 3 h.

[0050] (2) Weigh and mix the ingredients according to the stoichiometric ratio of 0.7(Bi 0.5 Na 0.5 )TiO3 - 0.3Ca 0.85 Bi 0.1 ZrO3 (abbreviated as BNT-CBZ) formula (with a precision of 0.0001 g), put it into a nylon ball mill tank containing zirconia grinding balls, add anhydrous ethanol and ball mill for 21 h.

[0051] (3) After the slurry is dried and sieved, pre-sinter at 840°C for 3 h to obtain the pre-sintered powder.

[0052] (4) Conduct secondary ball milling for 20 h, dry and sieve through an 80-mesh sieve to obtain the composite powder. Sinter the ceramic powder at 1120°C for 2 h to obtain BNT-CBZ ceramic particles.

[0053] 2. Preparation of ceramic particle / P(VDF-TrFE) mixed slurry

[0054] Dissolve 2 g of P(VDF-TrFE) powder in 40 ml of N,N-dimethylformamide (DMF), stir magnetically at 50°C for 4 h until completely dissolved to obtain a transparent solution. Add BNT-CBZ ceramic particles to the above P(VDF-TrFE) transparent solution to prepare a PVDF / BNT-CBZ mixed solution (the content of BNT-CBZ ceramic particles in the mixed solution is 2 wt%), then put the mixed solvent into an agate ball mill tank and carry out high-energy ball milling at a speed of 500 rmp / min for 30 min to obtain a mixed slurry; then put the solution into a vacuum mixer to defoam for 3 h to ensure that there are no bubbles in the solution.

[0055] 3. Tape casting

[0056] Using an ITO transparent conductive film as the substrate, the mixed slurry is cast in a casting machine. The distance between the doctor blade and the casting belt is set to 40 μm, and the traveling speed of the doctor blade is 30 cm / min. Finally, the uniform slurry is cast into a film strip with a thickness of 40 μm, and dried into a thick film at 60 °C. Then the sample is heated in a vacuum drying oven at a temperature of 80 °C for 10 h for curing, and then heated to 130 °C and held for 2 h to obtain a BNT-CBZ / polymer composite film. After cooling, the composite film is cut into a shape of 15 mm×15 mm, with a thickness of about 15 μm. A gold electrode with a diameter of 2 mm and a thickness of 40 nm is sputtered on the top mask to obtain a polymer composite film energy storage capacitor.

[0057] Example 3:

[0058] Preparation of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film energy storage capacitor:

[0059] 1. Preparation of Bi 0.5 Na 0.5 TiO3 (BNT) template grains:

[0060] The preparation method uses the molten salt method. Specifically, the reactants and salts are mixed in a certain ratio, heated to melt the salt, and then the reactants react in the molten salt to form the target product. The steps are as follows:

[0061] (1) Weigh Bi2O3 and TiO2 according to a molar ratio of 2:3, add a mixed powder of NaCl and KCl with the same mass as the reactant powder (the molar ratio of NaCl and KCl is 1:1), mix and place it in a ball mill jar, add ethanol and ball mill for 12 h, with a ball mill rotation speed of 280 r / min. Take it out, dry it and sieve it, put it in a crucible and keep it at 1080 °C for 1 h, and then repeatedly rinse off the salt with deionized water to obtain a Bi4Ti3O 12 precursor;

[0062] (2) Mix the Bi4Ti3O 12 precursor with TiO2 and Na2CO3 according to a molar ratio of 9:2:5. Similarly, add NaCl and KCl with the same mass as the reactant powder (the molar ratio of NaCl and KCl is 1:1), ball mill for 12 h, take it out, dry it and sieve it, put it in a crucible and keep it at 1080 °C for 1 h, and then repeatedly rinse off the salt with deionized water to obtain Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals;

[0063] (3) Mix the Na 0.5 Bi 4.5 Ti4O 15The flaky microcrystals are mixed with Na2CO3 in a molar ratio of 4:3, and a mixed powder of NaCl and KCl with the same mass as the reactant powder (the molar ratio of NaCl and KCl is 1:1) is added. After ball milling for 12 h, it is taken out, dried, and sieved. Then it is placed in a crucible and kept at 1060 °C for 3 h. Next, it is repeatedly rinsed with deionized water to remove the salt, and 6 mol / L HCl is used to remove the generated Bi2O3. The AgNO3 solution is used to test that there is no Cl ion in the solution. Finally, Bi 0.5 Na 0.5 TiO3 template crystals are obtained.

[0064] 2. Template-textured BNT-CBZ ceramic powder

[0065] The BNT-CBZ textured ceramics are prepared by the traditional solid-state sintering method. The steps are as follows:

[0066] (1) Select raw materials TiO2, Bi2O3, Na2CO3, CaO, ZrO2 (the purity of all raw materials is >98%). Dry the raw material raw powder at 100 °C for 3 h.

[0067] (2) Weigh the ingredients according to the stoichiometric ratio of 0.7(Bi 0.5 Na 0.5 )TiO3 - 0.3Ca 0.85 Bi 0.1 ZrO3 (abbreviated as BNT-CBZ) formula (with a precision of 0.0001 g), put it into a nylon ball mill tank containing zirconia grinding balls, and add anhydrous ethanol for ball milling for 21 h.

[0068] (3) After the slurry is dried and sieved, pre-sinter it at 850 °C for 3 h to obtain the pre-sintered powder.

[0069] (4) Mix the pre-sintered powder with the BNT seed crystal template prepared in the previous step for secondary ball milling (the mass ratio of the BNT seed crystal template to the pre-sintered powder is 1:20). The secondary ball milling time is 20 h. After drying, sieve it through an 80-mesh sieve to obtain the mixed powder.

[0070] (5) Sinter the mixed ceramic powder at 1120 °C for 2 h. During sintering, the ceramic powder grows under the action of the template grains to obtain BNT-CBZ textured ceramic powder with relatively consistent lattice orientation.

[0071] 3. Hydroxylation of the ceramic powder surface

[0072] Weigh 5 g of BNT-CBZ textured ceramic powder and disperse it into 50 ml of 35% hydrogen peroxide solution for surface hydroxylation. Stir magnetically at 90 °C for 3 h for full reaction with a rotation speed of 700 r / min. Then centrifuge for 10 minutes to obtain a precipitate with a centrifuge speed of 3000 rpm. Wash with distilled water and ethanol, and keep it warm in a vacuum drying oven at 70 °C for 8 h to obtain surface-hydroxylated BNT-CBZ nanoparticles (BNT-CBZ-OH).

[0073] 4. Prepare the ceramic particle / P(VDF-TrFE) mixed slurry

[0074] Dissolve 2 g of P(VDF-TrFE) powder in 40 ml of N,N-dimethylformamide (DMF), stir magnetically at 50 °C for 4 h until completely dissolved to obtain a transparent solution. Add the surface-hydroxylated BNT-CBZ nanoparticles to the above P(VDF-TrFE) transparent solution to prepare a PVDF / BNT-CBZ mixed solution (the content of BNT-CBZ-OH ceramic particles in the mixed solution is 2 wt%). Then put the mixed solvent into an agate ball milling tank and carry out high-energy ball milling at a rotation speed of 500 rmp / min for 30 min to obtain a mixed slurry; then put the solution into a vacuum mixer for defoaming for 3 h to ensure that there are no bubbles in the solution.

[0075] 5. Tape casting

[0076] Using an ITO transparent conductive film as the substrate, cast the slurry on a tape casting machine. Set the distance between the doctor blade and the casting belt to 40 μm, and the traveling speed of the doctor blade to 30 cm / min. Finally, cast the uniform slurry into a film strip with a thickness of 40 μm and dry it into a thick film at 60 °C; then heat the sample in a vacuum drying oven at a temperature of 80 °C for 10 h for curing, and then raise the temperature to 130 °C and keep it warm for 2 h to obtain a BNT-CBZ-OH / polymer composite film. After cooling, cut the composite film into a shape of 15 mm × 15 mm with a thickness of about 15 μm, and sputter a gold electrode with a diameter of 2 mm and a thickness of about 40 nm on the top mask to obtain a polymer composite film energy storage capacitor.

[0077] Example 4:

[0078] A preparation method of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film energy storage capacitor. The specific preparation process is the same as that of Example 3 above, except that the content of BNT-CBZ-OH ceramic particles in the mixed solution during the preparation of the ceramic particle / P(VDF-TrFE) mixed slurry is 5 wt%.

[0079] Example 5:

[0080] A preparation method of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite film energy storage capacitor, the specific preparation process is the same as that of Example 3 above, except that the content of BNT-CBZ-OH ceramic particles in the mixed solution is 10 wt% during the preparation of the ceramic particle / P(VDF-TrFE) mixed slurry.

[0081] Detection:

[0082] Perform electrical property tests on the polymer composite film energy storage capacitors of Examples 1-5:

[0083] 1. Dielectric property test:

[0084] Use a high and low temperature dielectric test system (GWJDN-600) combined with a precision LCR meter (Agilent E4980A) to perform dielectric response tests;

[0085] The dielectric spectrum results are as Figure 4 shown in (a). The dielectric constant of Example 1 without ceramic particle fillers is the lowest. With the incorporation of ceramic particles, the dielectric constant of the composite film energy storage capacitor corresponding to Example 2 increases. After the BNT-CBZ ceramic particles are textured and hydroxylated, the dielectric constant increases significantly. As shown in #3 in the figure, when the content of BNT-CBZ-OH ceramic particles in the mixed solution is 10 wt%, the dielectric constant is the largest, reaching 12.53. In addition, from Figure 4 the dielectric loss spectrum of (b), it can be seen that as the content of BNT-CBZ-OH ceramics increases, the dielectric loss increases, but is less than 0.2, showing good insulation performance.

[0086] See Table 1 below for details:

[0087] Table 1

[0088]

[0089] 2. Perform the maximum withstand field strength (breakdown field strength) test on the composite film energy storage capacitors prepared in Examples 1-5. The test method is to immerse the sample in silicone oil and measure it at 1 Hz using a ferroelectric test system combined with a high voltage power supply (TREK-610E).

[0090] The specific results are shown in Figure 5 and Table 2 below. The breakdown field strength of the pure P(VDF-TrFE) polymer film corresponding to Example 1 is the smallest, 310 kV / mm. After adding ceramic particles, the breakdown field strength is improved. After texturing and hydroxylation treatment, the breakdown field strength is even greater. When the content of hydroxylated BNT-CBZ-OH ceramic particles is 5 wt%, the breakdown field strength reaches the maximum, 480 kV / mm. Higher contents such as in Example 5 result in a decrease in the breakdown field strength.

[0091] Table 2

[0092]

[0093] 3. Compare the single - polarization hysteresis loops of the composite - film energy - storage capacitors prepared in Examples 1 - 5;

[0094] The specific results are as Figure 6 and Table 3 below. The applied electric field is the maximum tolerable field strength of each example. It can be seen that the polarization intensity value of Example 4 is the largest, which is 10.1 mC / cm 2 , indicating that the performance is the best when the content of hydroxylated BNT - CBZ - OH ceramic particles added is 5 wt%.

[0095] Table 3

[0096]

[0097] According to the hysteresis loop, the effective energy - storage density of each example can be calculated. Figure 7 And Table 4 below lists the corresponding effective energy - storage density values of the polymer composite - film energy - storage capacitors of each example. It can be seen that the ceramic - particle composite can significantly improve the energy - storage density, and the performance is the best when the content of hydroxylated BNT - CBZ - OH ceramic particles is 5 wt%. That is, the effective energy - storage density of Example 4 reaches 13.8 J / cm 3 at a relatively high level.

[0098] Table 4

[0099]

[0100] The above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a flexible hydroxyl-modified BNT-CBZ-OH ceramic particle / polymer composite membrane, characterized in that, The preparation method includes the following steps: S1. Prepare Bi 0.5 Na 0.5 TiO3 (BNT) template grains: S1-1: Prepare a Bi4Ti3O precursor using Bi2O3 and TiO2 12 precursor; S1-2. Mix the Bi4Ti3O 12 precursor with TiO2 and Na2CO3, ball-mill the mixture and then sinter it to obtain Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals; S1-3. Mix Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals with Na2CO3, ball-mill and then sinter, and then remove Bi2O3 from the product to obtain Bi 0.5 Na 0.5 TiO3 template crystals, i.e., BNT seed crystal templates; S2. Template-textured BNT-CBZ ceramic powder: According to the formula of 0.7(Bi 0.5 Na 0.5 )TiO3 - 0.3Ca 0.85 Bi 0.1 ZrO3, weigh the raw materials and mix them for ball milling. Then, heat up for pre-sintering, and mix with BNT seed crystal template for ball milling and sintering to obtain BNT-CBZ textured ceramic powder; S3. Surface hydroxylation of ceramic powder: Dispersing BNT-CBZ textured ceramic powder into hydrogen peroxide solution for surface hydroxylation treatment to obtain BNT-CBZ-OH ceramic particles; and the specific operation of surface hydroxylation is to disperse BNT-CBZ textured ceramic powder at a ratio of 1 g∶10 ml into hydrogen peroxide solution with a concentration of 35%, magnetically stirring at a speed of 500-800 r / min at 80-100 °C for 3 h for full reaction; after the reaction, centrifuging at a speed of 3000 rpm for 8-10 minutes to obtain a precipitate; washing the precipitate with distilled water and ethanol and then keeping it warm in a vacuum drying oven at 70-100 °C for 8-12 h to obtain BNT-CBZ-OH ceramic particles; S4. Preparation of ceramic particle / P(VDF-TrFE) mixed slurry: Dissolving P(VDF-TrFE) in N,N-dimethylformamide, and then adding BNT-CBZ-OH ceramic particles to obtain ceramic particle / P(VDF-TrFE) mixed slurry; S5. Tape casting: Casting the above mixed slurry on a substrate in a tape casting machine and curing to form a composite film.

2. The preparation method according to claim 1, characterized in that: The specific process in the step S1-1 is to mix Bi2O3 and TiO2 with a molar ratio of 2:3 into reaction powder, and then add a mixed powder with the same mass as the reactant powder. After mixing, it is placed in a ball mill jar and ball milled with ethanol for 10-12 h at a ball milling speed of 250-300 r / min. Then it is taken out, dried, and sieved, placed in a crucible, kept at 1080 °C for 1 h, and then repeatedly rinsed with deionized water to remove salts, obtaining Bi4Ti3O 12 precursor; and the mixed powder is obtained by mixing NaCl and KCl with a molar ratio of 1:

1.

3. The preparation method according to claim 1, characterized in that: In the specific process of step S1-2, Bi4Ti3O 12 precursor is mixed with TiO2 and Na2CO3 in a molar ratio of 9:2:5 to obtain a reactant powder. Then, a mixed powder with the same mass as the reactant powder is added, and the mixture is ball-milled for 10-12 h. After that, it is taken out, dried, and sieved. Then it is placed in a crucible and kept at 1080 °C for 1 h. Next, it is repeatedly rinsed with deionized water to remove salts, obtaining Na 0.5 Bi 4.5 Ti4O 15 flake-shaped microcrystals; the mixed powder is obtained by mixing NaCl and KCl in a molar ratio of 1:

1.

4. The preparation method according to claim 1, characterized in that: The specific steps in the step S1-3 are to mix Na 0.5 Bi 4.5 Ti4O 15 flake microcrystals and Na2CO3 in a molar ratio of 4:3 to obtain a reactant powder, add a mixed powder with the same mass as the reactant powder, ball mill for 10-12 h, take out, dry and sieve, put it into a crucible and keep it at 1060 °C for 3 h, then repeatedly rinse off the salt with deionized water, and remove the generated Bi2O3 with 6 mol / L HCl to obtain Bi 0.5 Na 0.5 TiO3 template crystals; the mixed powder is obtained by mixing NaCl and KCl in a molar ratio of 1:

1.

5. The preparation method according to claim 1, wherein: In step S2, the raw materials are selected as TiO2, Bi2O3, Na2CO3, CaO, ZrO2, and the purity of each raw material is >98%, and the raw materials are dried at 80-100 °C for more than 3 h before use.

6. The preparation method according to claim 1, characterized in that: The specific steps in step S2 are as follows: S2-1. Placing the weighed raw materials in a nylon ball milling tank containing zirconia grinding balls, adding anhydrous ethanol for ball milling for 10-24 h, and then heating to 800-900 °C for pre-sintering for 2-3 h to obtain pre-sintered powder; S2-2. Mixing the pre-sintered powder and BNT seed crystal templates by ball milling according to a mass ratio of 1-3∶10-50, continuing ball milling for 10-20 h, and then drying and sieving through a 80-mesh sieve to obtain mixed powder; S2-3. Sintering the mixed powder at 1050-1150 °C for 2-3 h to obtain BNT-CBZ textured ceramic powder.

7. The preparation method according to claim 1, characterized in that: In step S4, the ratio of P(VDF-TrFE) powder dissolved in N,N-dimethylformamide is 1 g∶20 ml; and the content of BNT-CBZ-OH ceramic particles in the mixed slurry accounts for 2 wt%-10 wt%, and after mixing, high-energy ball milling is carried out at a speed of 300-500 rmp / min for 20-30 min and then degassing in a vacuum mixer for 3 h.

8. The preparation method according to claim 1, characterized in that: In step S5, the distance between the doctor blade and the tape casting base during tape casting is set to 20-100 μm, the traveling speed of the doctor blade is 20-50 cm / min, and it is dried into a thick film at 40-80 °C, and then heated to 50-90 °C in a vacuum drying oven, cured for 5-10 h, and then heated to 130 °C and kept warm for 2-3 h to obtain a BNT-CBZ-OH / polymer composite film.

9. Use of a composite membrane prepared by any of the preparation methods according to claims 1-8 in the preparation of an energy storage capacitor, characterized in that: The application method is to use an ITO transparent conductive film as the substrate, cast a BNT-CBZ-OH / polymer composite film on the ITO transparent conductive film, and then sputter a gold electrode on the top mask.

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