Functional filler based on CCTO and BSCZT, preparation method of functional filler, flexible medium composite membrane and application of flexible medium composite membrane

Abstract

The invention relates to a functional filler based on CCTO (at) BSCZT, a preparation method, a flexible medium composite film and application, the functional filler comprises a CaCu3Ti4O12 (at) Ba < 0.34 > Sr < 0.51 > Ca < 0.15 > Zr < 0.1 > Ti < 0.9 > O < 3 > core-shell structure, and CaCu3Ti4O12 and Ba < 0.34 > Sr < 0.51 > Ca < 0.15 > Zr < 0.1 > Ti < 0.9 > O < 3 > form a type II heterojunction through energy band matching. Furthermore, the surface of the CaCu3Ti4O12-coated Ba < 0.34 > Sr < 0.51 > Ca < 0.15 > Zr < 0.1 > Ti < 0.9 > O < 3 > core-shell structure is further coated with an Al2O3 shell layer, so that CaCu3Ti4O12-coated Ba < 0.34 > Sr < 0.51 > Ca < 0.15 > Zr < 0.1 > Ti < 0.9 > O < 3 >-coated Al2O3 is formed. In the functional filler, efficient separation of electrons and holes is promoted by utilizing dislocation of a conduction band and a valence band at an II-type heterojunction interface, and polarization response is enhanced; al2O3 is coated on the surface of the CaCu3Ti4O12 and Ba < 0.34 > Sr < 0.51 > Ca < 0.15 > Zr < 0.1 > Ti < 0.9 > O < 3 > core-shell structure, and the Al2O3 plays a role in reducing loss. When the functional filler is applied to a flexible dielectric medium, the loss can be reduced, and the effective polarization intensity and energy storage density can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a functional filler based on CCTO@BSCZT and its preparation method, a flexible dielectric composite membrane and its application. Background Technology

[0002] Electrostatic discharge (ESD) capacitors are energy storage devices that utilize the polarization and depolarization of a functional dielectric sandwiched between two metal electrodes to achieve charging and discharging under the influence of an electric field. The core material determining their performance is the functional dielectric. ESD capacitors offer advantages such as high power density, rapid charging and discharging, long service life, and no risk of leakage. ESD capacitors using flexible dielectrics play a crucial role not only in high-voltage power transmission, electric vehicles, solar / wind power generation, pulsed power systems, and aerospace equipment, but also in the development of flexible and miniaturized electronic devices. These applications require flexible dielectrics with high dielectric constants, high energy density, and low losses; these are key parameters ensuring small size and large capacity. Therefore, achieving and maintaining high dielectric constants, high energy density, and low losses under application conditions has become an important research topic for high-performance flexible dielectrics.

[0003] Biaxially oriented polypropylene (BOPP) is the most commonly used commercial flexible dielectric, but it has two key limitations: firstly, its dielectric constant is small (2.2), and secondly, its energy storage density is low (<2 J / cm³). 3 Firstly, BOPP capacitors are bulky, making them difficult to miniaturize. Secondly, to accommodate large-capacity applications, BOPP requires large-area winding, which causes the capacitors to lose flexibility and fails to meet the development trend of flexible devices. Meanwhile, polyvinylidene fluoride (PVDF)-based flexible dielectrics, which have attracted widespread attention in academia, have energy storage densities exceeding 35 J / cm². 3 However, its high energy density can only be achieved under extremely high electric field strength, and its energy storage performance under low electric field strength is still poor, which greatly limits the practical application scenarios of electrostatic energy storage capacitors. The key to further improving the performance of electrostatic energy storage capacitors lies in significantly increasing their effective polarization intensity while ensuring that the flexible functional dielectric has low loss characteristics.

[0004] Therefore, developing a low-loss flexible dielectric that can significantly improve the effective polarization intensity is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a functional filler based on CCTO@BSCZT, its preparation method, a flexible dielectric composite membrane, and its applications. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a functional filler based on CCTO@BSCZT, comprising: CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 core-shell structure, in which CaCu3Ti4O 12 with Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 forms a type II heterojunction through band matching.

[0006] In one embodiment of the present invention, the CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The surface of the O3 core-shell structure is coated with an Al2O3 shell, forming CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3.

[0007] Secondly, the present invention provides a method for preparing a functional filler based on CCTO@BSCZT, comprising the steps of: following Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The stoichiometric ratio of O3 is as follows: barium acetate, calcium acetate, and strontium acetate are weighed and added to a mixed solution of glacial acetic acid and deionized water, and stirred until homogeneous to obtain the first solution; tetrabutyl titanate, zirconium n-butoxide, and acetylacetone are added to a mixed solution of glacial acetic acid and anhydrous ethanol, and stirred until homogeneous to obtain the second solution; the first solution is added dropwise to the second solution, and stirred to form a sol; CaCu3Ti4O 12 The powder was added to the sol and stirred for a period of time, then stirred under heating conditions to form a gel. The gel was dried and ground, then an aqueous sodium hydroxide solution was added and stirred until homogeneous. A hydrothermal reaction was then carried out to obtain the product. Finally, the product was washed and dried to obtain CaCu3Ti4O. 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 powder.

[0008] In one embodiment of the present invention, the preparation method of the functional filler based on CCTO@BSCZT further includes the step of: weighing the CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 powder was added to deionized water and anhydrous ethanol, and the mixture was ultrasonicated and stirred to obtain a suspension. Aluminum nitrate was weighed and added to deionized water and stirred evenly to obtain a third solution. The third solution was poured into the suspension and stirred. The pH of the mixed solution was then adjusted to 9-10, and stirring was continued for a period of time. After centrifugation, washing, and drying, the mixture was calcined to obtain CaCu3Ti4O. 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 powder.

[0009] Thirdly, the present invention provides a flexible dielectric composite film based on CCTO@BSCZT, wherein the flexible dielectric composite film is CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 / polymer.

[0010] In one embodiment of the present invention, the flexible dielectric composite film is CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 / polymer.

[0011] In one embodiment of the present invention, the flexible dielectric composite film is a multilayer composite film, the multilayer composite film comprising a bottom layer, a transition layer, and a polarization layer stacked sequentially, wherein the bottom layer is made of a polymer; the transition layer is made of Ba. 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3-Y@ Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9O3-Mn@Al2O3 / polymer; the polarization layer material includes CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 / polymer.

[0012] Fourthly, the present invention provides an application of the flexible dielectric composite film based on CCTO@BSCZT as described in the above embodiments in an energy storage capacitor.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is based on the functional filler CCTO@BSCZT, containing CaCu3Ti4O 12 (CCTO) and Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3(BSCZT) forms a type II heterojunction through band matching. The misalignment of the conduction band and valence band at its interface promotes efficient electron-hole separation, thereby enhancing the polarization response. When applied to flexible dielectrics, it can significantly improve the effective polarization intensity. 2. In the functional filler based on CCTO@BSCZT, the surface of the CCTO@BSCZT core-shell structure is coated with an Al2O3 shell layer. The ultra-wide bandgap and high resistivity of Al2O3 are used to block the interfacial charge migration, alleviate the dielectric mismatch between the filler and the polymer matrix, reduce losses, and improve the thermal stability and breakdown field strength of the composite system. 3. In the CCTO@BSCZT / polymer composite film of the present invention, under an applied electric field, the voltage falls more on the BSCZT. On the one hand, the increased polarization of the BSCZT can increase the polarization intensity of the flexible composite dielectric. On the other hand, electrons migrate from the CCTO conduction band in the type II heterojunction CCTO@BSCZT to the BSCZT, and holes migrate from the valence band of the BSCZT to the CCTO, resulting in space charge separation. Under the action of the external electric field, electrons and holes move in opposite directions, which intensifies the polarization phenomenon. Under the above dual effects, the polarization intensity and dielectric properties of the CCTO@BSCZT / P(VDF-HFP) composite film are improved, and the energy storage performance is improved. 4. In the CCTO@BSCZT@Al2O3 / polymer composite film of the present invention, based on the improvement of polarization intensity by CCTO@BSCZT, Al2O3 is used as a barrier layer to restrict charge movement, and free electrons are captured by deep traps to reduce leakage current and dielectric loss, thereby improving the energy storage performance of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite film; 5. In the multilayer composite film of the present invention, an asymmetric three-layer film structure of bottom layer, transition layer and polarization layer is adopted. The synergistic effect of bottom layer and transition layer helps to improve electric field distribution, reduce breakdown risk and significantly improve the breakdown field strength of film material. At the same time, polarization layer further enhances the dielectric constant of composite film. Therefore, this multilayer composite film can not only improve dielectric constant, but also enhance breakdown strength and ensure mechanical flexibility, which can meet the demand for high-performance dielectric materials in complex working environments. Attached Figure Description

[0014] Figure 1 A schematic flowchart illustrating the preparation method of the functional filler CCTO@BSCZT provided in this embodiment of the invention; Figure 2 A schematic flowchart illustrating the preparation method of the functional filler CCTO@BSCZT@Al2O3 provided in this embodiment of the invention; Figure 3 XRD patterns of CCTO@BSCZT powders in different proportions; Figure 4 SEM images of CCTO@BSCZT powders in different proportions; Figure 5 TEM image of CCTO@BSCZT(1:1) powder; Figure 6 Mapping elemental analysis diagram of CCTO@BSCZT(1:1) powder; Figure 7 The bandgap analysis diagram for BSCZT; Figure 8 UV-Vis spectra and Tauc diagrams of BSCZT, CCTO@BSCZT with different proportions, and CCTO; Figure 9 Valence band test plots for CCTO and BSCZT; Figure 10 XRD patterns of CCTO@BSCZT@Al2O3 powders in different proportions; Figure 11 SEM images of CCTO@BSCZT@Al2O3 powders with different proportions; Figure 12 XPS spectrum of CCTO@BSCZT(0.5:1)@Al2O3; Figure 13 A schematic flowchart of the method for preparing a flexible dielectric composite film based on CCTO@BSCZT provided in an embodiment of the present invention; Figure 14 XRD patterns of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios; Figure 15 SEM images of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios; Figure 16 FTIR spectra of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios; Figure 17 The trend graphs of dielectric constant and dielectric loss of CCTO@BSCZT / P(VDF-HFP) composite film at different frequencies; Figure 18 This is a diagram showing the relative band positions of CCTO and BSCZT. Figure 19 Weibull plot and breakdown field strength plot of CCTO@BSCZT / P(VDF-HFP) composite membrane; Figure 20 To investigate the effects of different filler ratios on CCTO@BSCZT / P(VDF-HFP) composite membranes in Weibull E b Next test P-E curve; Figure 21 XRD patterns of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membranes with different filler ratios; Figure 22 SEM images of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membranes with different filler ratios; Figure 23 The FTIR spectrum of the CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite film; Figure 24 Dielectric properties of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite films with different ratios; Figure 25 The polarization mechanism diagram of the filler in CCTO@BSCZT@Al2O3 / P(VDF-HFP); Figure 26 Weibull plot and breakdown field strength plot of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membrane; Figure 27The CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membrane under breakdown field strength P-E curve; Figure 28 This is a schematic diagram of the structure of the multilayer composite membrane provided in an embodiment of the present invention; Figure 29 XRD pattern of CBAP / YMAP / P multilayer composite film; Figure 30 SEM images and EDS spectra of cross-sections of CBAP / YMAP / P multilayer composite films; Figure 31 For CBAP / YMAP / P multilayer composite membrane ε r and tan δ Graph showing variation with frequency; Figure 32 Weibull distribution of CBAP / YMAP / P composite membrane and E b Below P-E curve. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0016] Example 1 This embodiment provides a functional filler based on CCTO@BSCZT, which includes CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The O3(CCTO@BSCZT) core-shell structure, wherein CCTO and BSCZT form a type II heterojunction through band matching.

[0017] Specifically, a Type II heterojunction refers to a heterojunction with staggered band structures. In the Type II CCTO@BSCZT heterojunction system, due to the energy level misalignment between the conduction and valence bands of CCTO and BSCZT, this band structure difference drives electrons to migrate from the conduction band of CCTO to the conduction band of BSCZT, while holes transfer from the valence band of BSCZT to the valence band of CCTO. Spatial separation effectively suppresses electron-hole recombination, significantly improving polarization response and optimizing dielectric properties by enhancing the dipole orientation of the matrix material, thereby increasing the energy storage density of the composite dielectric.

[0018] In one specific embodiment, the surface of the CCTO@BSCZT core-shell structure is coated with an Al2O3 shell, forming a functional filler for the CCTO@BSCZT@Al2O3 structure. It should be noted that the surface of the CCTO@BSCZT core-shell structure can also be coated with other inorganic materials, such as SiO2; this embodiment does not impose further limitations.

[0019] Specifically, in the CCTO@BSCZT core-shell structure and the CCTO@BSCZT@Al2O3 structure, the molar ratio of CCTO to BSCZT is (0.25~2):1.

[0020] This embodiment also provides a method for preparing functional fillers based on CCTO@BSCZT.

[0021] Please see Figure 1 , Figure 1 This is a schematic flowchart of a method for preparing the functional filler CCTO@BSCZT according to an embodiment of the present invention. The method uses a sol-gel-hydrothermal process to prepare CCTO@BSCZT powder, and specifically includes the following steps: S1, according to Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The stoichiometric ratio of O3 is determined by weighing barium acetate, calcium acetate, and strontium acetate and adding them to a mixed solution of glacial acetic acid and deionized water. After stirring evenly, the first solution is obtained.

[0022] Specifically, the molar ratio of barium acetate: calcium acetate: strontium acetate: deionized water: glacial acetic acid is 2.26:1:3.39:161.5:25.4. The mixture should be stirred for 20-40 minutes to ensure homogeneity.

[0023] S2. Add tetrabutyl titanate, zirconium n-butoxide and acetylacetone to a mixed solution of glacial acetic acid and anhydrous ethanol, and stir until homogeneous to obtain a second solution.

[0024] Specifically, the molar ratio of tetrabutyl titanate: zirconium n-butoxide: acetylacetone: glacial acetic acid: anhydrous ethanol is 3.68:0.57:0.71:12.67:82.36. The mixture should be stirred for 20-40 minutes to achieve homogeneity.

[0025] S3. Add the first solution dropwise into the second solution and stir to form a sol. Specifically, the stirring time is 2-4 hours.

[0026] S4. Add CCTO powder to the sol and continue stirring for a period of time, then stir under heating conditions to form a gel.

[0027] Specifically, CCTO powder is added to the sol and stirred for 3-4 hours, then heated and stirred in a water bath at 60-70 °C for 30-40 minutes to form a gel. The molar ratio of CCTO to BSCZT is (0.25-2):1, and the proportion of BSCZT is calculated based on the proportion of BSCZT raw materials in steps S1 and S2; the diameter of CCTO particles is 200-400 nm.

[0028] S5. After drying and grinding the gel, add sodium hydroxide aqueous solution and stir evenly. Then carry out hydrothermal reaction to obtain the product. Finally, wash and dry the product to obtain CCTO@BSCZT powder, wherein CCTO and BSCZT form a type II heterojunction through band matching.

[0029] Specifically, after drying and grinding the gel, a 4 mol / L sodium hydroxide aqueous solution was added. Based on BSCZT being 1 mol, the amount of sodium hydroxide added was 10.06 mol. After stirring for 1-2 h, a hydrothermal reaction was carried out at 150-200 ℃ for 8-20 h. Finally, the product was repeatedly washed and dried with deionized water and anhydrous ethanol to obtain CCTO@BSCZT powder.

[0030] Please see Figure 2 , Figure 2 This is a schematic flowchart of a method for preparing the functional filler CCTO@BSCZT@Al2O3 provided in an embodiment of the present invention. This method further synthesizes CCTO@BSCZT@Al2O3 powder using a precipitation method based on CCTO@BSCZT powder, and specifically includes the following steps: S1. Weigh CCTO@BSCZT powder, add deionized water and anhydrous ethanol, and sonicate and stir to obtain a suspension.

[0031] Specifically, the ratio of CCTO@BSCZT powder, deionized water, and anhydrous ethanol is 1g:30ml:30ml. The sonication time is 20-40 minutes, and the stirring time is 20-30 minutes.

[0032] S2. Weigh aluminum nitrate and add it to deionized water, stir well to obtain the third solution.

[0033] Specifically, the ratio of aluminum nitrate to deionized water is 0.2944g:30ml, and the stirring time is 30~50 min.

[0034] S3. Pour the third solution into the suspension and stir. Then adjust the pH of the mixed solution to 9-10, continue stirring for a period of time, centrifuge, wash, dry, and then calcine to obtain CCTO@BSCZT@Al2O3 powder.

[0035] Specifically, the third solution is poured into the suspension and stirred for 1-2 hours. Ammonia water is added dropwise to adjust the pH of the mixed solution to 9-10. Stirring continues for 12-15 hours. After centrifugation, washing, and drying with deionized water and anhydrous ethanol, the solution is placed in a muffle furnace and calcined at 500-600℃ for 2-2.5 hours to obtain Al2O3-coated powder CCTO@BSCZT@Al2O3.

[0036] To facilitate understanding of the present invention, the following examples are provided.

[0037] Example 1 CCTO@BSCZT (0.25:1) powder was prepared using a sol-gel-hydrothermal method, including the following steps: S1. Weigh barium acetate, calcium acetate, and strontium acetate according to the stoichiometric ratio of BSCZT and add them to a mixed solution of glacial acetic acid and deionized water. The molar ratio of barium acetate: calcium acetate: strontium acetate: deionized water: glacial acetic acid is 2.26:1:3.39:161.5:25.4. Then stir the mixed solution thoroughly for 30 min to obtain the first solution.

[0038] S2. Add tetrabutyl titanate, zirconium n-butoxide, and acetylacetone to a mixed solution of glacial acetic acid and anhydrous ethanol. The molar ratio of tetrabutyl titanate: zirconium n-butoxide: acetylacetone: glacial acetic acid: anhydrous ethanol is 3.68: 0.57: 0.71: 12.67: 82.36. Then stir the mixed solution thoroughly for 30 min to obtain the second solution.

[0039] S3. Add the first solution dropwise into the second solution and stir for 3 hours to form a sol.

[0040] S4. Add CCTO powder to the sol and continue stirring for 3 hours. Then, heat and stir in a 65°C water bath for 30 minutes to form a gel. The molar ratio of CCTO to BSCZT is 0.25:1.

[0041] S5. After drying and grinding the gel, add a 4 mol / L sodium hydroxide aqueous solution. Calculate 1 mol of BSCZT, the amount of sodium hydroxide added is 10.06 mol. Stir for 1 h and then carry out a hydrothermal reaction at 180℃ for 12 h. Finally, wash and dry the product repeatedly with deionized water and anhydrous ethanol to obtain CCTO@BSCZT(0.25:1) powder.

[0042] Example 2 CCTO@BSCZT (0.5:1) powder was prepared using a sol-gel-hydrothermal method. The difference from Example 1 is that the molar ratio of CCTO to BSCZT is 0.5:1, while the other conditions are the same.

[0043] Example 3 CCTO@BSCZT (1:1) powder was prepared using a sol-gel-hydrothermal method. The difference from Example 1 is that the molar ratio of CCTO to BSCZT is 1:1, while the other conditions are the same.

[0044] Example 4 CCTO@BSCZT (2:1) powder was prepared using a sol-gel-hydrothermal method. The difference from Example 1 is that the molar ratio of CCTO to BSCZT is 2:1, while the other conditions are the same.

[0045] Characterization tests were performed on the materials in Examples 1 to 4.

[0046] Please see Figure 3 , Figure 3 XRD patterns of CCTO@BSCZT powders with different proportions are shown. All samples exhibit a pure ABO3 perovskite structure, and no impurities were detected. It can be seen that the prepared CCTO@BSCZT powders possess the characteristic diffraction peaks of both CCTO and BSCZT. (The last sentence appears to be incomplete and possibly refers to Ba...) 0.5 Sr 0.5 Compared to TiO3 (PDF#39-1395), 2 θ= 22.6°, 32.2°, 39.7°, 46.2°, 52.1°, 57.5°, 67.4°, 72.1°, and 76.7° correspond to the (100), (110), (111), (200), (210), (211), (220), and (310) crystal planes of BSCZT, respectively. (The last sentence appears to be incomplete and possibly refers to CaCu3Ti4O.) 12 (PDF#21-0140) In comparison, 2 θ= 16.9°, 34.5°, 49.5°, 61.8°, and 72.7° correspond to the (110), (220), (400), (422), and (440) crystal planes of CCTO, respectively. The characteristic peaks of CCTO and BSCZT exist independently without peak shift, indicating that they do not form a solid solution but are physically bonded through a heterojunction interface, demonstrating the successful preparation of CCTO@BSCZT powder.

[0047] Please see Figure 4 , Figure 4 SEM images of CCTO@BSCZT powders with different ratios are shown. (a), (b), (c), and (d) correspond to CCTO@BSCZT (0.25:1), CCTO@BSCZT (0.5:1), CCTO@BSCZT (1:1), and CCTO@BSCZT (2:1), respectively. The images show that the powders have relatively small particle sizes, and localized aggregation occurs due to the high surface energy of the powders.

[0048] Please see Figure 5 ,Figure 5 The image shows a TEM image of CCTO@BSCZT (1:1) powder. As can be seen from the image, CCTO is coated with BSCZT. The interplanar spacing marked 1 is 2.62 Å, corresponding to the (220) facet of CCTO, while the spacing marked 2 is 2.82 Å, corresponding to the (110) facet of BSCZT. This correspondence in interplanar spacing further confirms the formation of the CCTO@BSCZT heterostructure.

[0049] Please see Figure 6 , Figure 6 The mapping elemental analysis diagram of CCTO@BSCZT(1:1) powder shows that the elemental distribution of CCTO@BSCZT(1:1) powder is uniform.

[0050] The Tauc plot of the UV-Vis spectrum of BSCZT was analyzed using Equation (1). The analysis results can be found in [link to analysis]. Figure 7 , Figure 7 This is a bandgap analysis diagram of BSCZT.

[0051] (1) in, The absorption coefficient is... Photon energy, For band gap, It is a constant.

[0052] Depend on Figure 7 Analysis of the optical bandgap of BSCZT reveals a clear linear region when fitted using a direct bandgap model, with a corresponding bandgap value of 3.32 eV. This indicates that direct transitions dominate its optical transition process, suggesting that BSCZT may possess direct bandgap characteristics.

[0053] Please see Figure 8 , Figure 8 The UV-Vis spectra and Tauc plots of BSCZT, CCTO@BSCZT with different proportions, and CCTO are shown. (a) shows the UV-Vis spectra, measured using a Shimadzu UV-3600 Plus (UV-vis) microscope at wavelengths of 200–800 nm. (b) shows the Tauc plots. Tauc plots were used to calculate... E gAccording to formula (1), the band gaps of BSCZT, CCTO@BSCZT(0.25:1), CCTO@BSCZT(0.5:1), CCTO@BSCZT(1:1), CCTO@BSCZT(2:1), and CCTO are calculated to be 3.32 eV, 3.03 eV, 2.73 eV, 2.19 eV, 2.08 eV, and 1.98 eV, respectively. As the CCTO content gradually increases, the band gap of CCTO@BSCZT shows a continuous decreasing trend, gradually approaching the intrinsic band gap value of pure CCTO. Combined with the XRD results, no new phase was observed to form in CCTO@BSCZT, but rather CCTO and BSCZT coexisted, thus inferring that CCTO@BSCZT formed a heterojunction structure.

[0054] Please see Figure 9 , Figure 9 The valence band test plots for CCTO and BSCZT are shown, where (a) is CCTO and (b) is BSCZT. The valence band positions of CCTO and BSCZT are 0.8 eV and 2.2 eV, respectively.

[0055] Example 5 CCTO@BSCZT(0.25:1)@Al2O3 powder was synthesized by precipitation method, including the following steps: S1. Weigh 1g of CCTO@BSCZT(0.25:1) powder to be coated, add 30ml of deionized water and 30ml of anhydrous ethanol, sonicate for 30min, and then stir for 30min to obtain a suspension.

[0056] S2. Weigh 0.2944g of aluminum nitrate and add it to 30ml of deionized water. Stir for 30min to obtain the third solution.

[0057] S3. Pour the third solution into the suspension, stir for 1 hour, add ammonia water dropwise to adjust the pH of the mixed solution to 9-10, stir for 12 hours, wash and dry with deionized water and anhydrous ethanol by centrifugation, and then calcine in a muffle furnace at 500℃ for 2 hours to obtain powder coated with Al2O3.

[0058] Example 6 CCTO@BSCZT(0.5:1)@Al2O3 powder was synthesized by precipitation method. The difference from Example 5 is that the powder to be coated in step S1 is CCTO@BSCZT(0.5:1), while the other conditions are the same.

[0059] Example 7 CCTO@BSCZT(1:1)@Al2O3 powder was synthesized by precipitation method. The difference from Example 5 is that the powder to be coated in step S1 is CCTO@BSCZT(1:1), while the other conditions are the same.

[0060] Example 8 CCTO@BSCZT(2:1)@Al2O3 powder was synthesized by precipitation method. The difference from Example 5 is that the powder to be coated in step S1 is CCTO@BSCZT(2:1), while the other conditions are the same.

[0061] Characterization tests were performed on the materials in Examples 5 to 8.

[0062] Please see Figure 10 , Figure 10 XRD patterns of CCTO@BSCZT@Al2O3 powders with different proportions are shown. All samples exhibit a pure ABO3 perovskite structure, and no impurities were detected. It can be seen that the prepared CCTO@BSCZT@Al2O3 powders possess the characteristic diffraction peaks of CCTO and BSCZT. (The last sentence appears to be incomplete and possibly contains errors.) 0.5 Sr 0.5 Compared to TiO3 (PDF#39-1395), where 2 θ= 22.6°, 32.2°, 39.7°, 46.2°, 52.1°, 57.5°, 67.4°, 72.1°, and 76.7° correspond to the (100), (110), (111), (200), (210), (211), (220), and (310) crystal planes of BSCZT, respectively. (The last sentence appears to be incomplete and possibly refers to CaCu3Ti4O.) 12 (PDF#21-0140) In comparison, 2 θ= 16.9°, 34.5°, 49.5°, 61.8°, and 72.7° correspond to the (110), (220), (400), (422), and (440) crystal planes of CCTO, respectively. The characteristic peaks of CCTO and BSCZT exist independently without any peak shift, indicating that they do not form a solid solution but are physically bonded through a heterojunction interface. Due to the limitations of XRD precision, the Al2O3 coating layer is relatively thin, and its diffraction peaks were not detected.

[0063] Please see Figure 11 , Figure 11 SEM images of CCTO@BSCZT@Al2O3 powders with different ratios are shown. (a), (b), (c), and (d) correspond to CCTO@BSCZT(0.25:1)@Al2O3, CCTO@BSCZT(0.5:1)@Al2O3, CCTO@BSCZT(1:1)@Al2O3, and CCTO@BSCZT(2:1)@Al2O3, respectively. The powder particles in the images are relatively small, and local aggregation occurs due to the high surface energy.

[0064] Please see Figure 12 , Figure 12The image shows the XPS spectrum of CCTO@BSCZT(0.5:1)@Al2O3, which corresponds to Ba3. d Sr 3 d Ca 2 p Zr 3 d Ti 2 p O 1 s C 1 s Cu 2 p and Al 2 p The characteristic peaks indicate that Al2O3 was successfully coated on the surface of CCTO@BSCZT(0.5:1) powder.

[0065] In this embodiment, CCTO and BSCZT form a type II heterojunction through band matching. The misalignment of the conduction band and valence band at their interface promotes efficient electron-hole separation, effectively suppresses carrier recombination, and thus enhances polarization response. When applied to flexible dielectrics, it can significantly improve the effective polarization intensity.

[0066] In this embodiment, an Al2O3 shell is coated on the surface of the CCTO@BSCZT core-shell structure. The ultrawide bandgap and high resistivity of Al2O3 are used to block interfacial charge migration, alleviate dielectric mismatch between the filler and the polymer matrix, reduce losses, and improve the thermal stability and breakdown field strength of the composite system.

[0067] Example 2 Based on Example 1, this example provides a flexible dielectric composite membrane based on CCTO@BSCZT.

[0068] In a specific example, the flexible dielectric composite membrane includes a functional filler and a matrix material. The functional filler includes a CCTO@BSCZT core-shell structure, where CCTO and BSCZT form a type II heterojunction through band matching. The matrix material includes a polymer, which includes, but is not limited to, one or more of PVDF, P(VDF-HFP), P(VDF-TrFE), PI, and PEI. Accordingly, the flexible dielectric composite membrane is CCTO@BSCZT / polymer, for example, CCTO@BSCZT / P(VDF-HFP).

[0069] In another specific example, the flexible dielectric composite membrane includes a functional filler and a matrix material. The functional filler includes CCTO@BSCZT@Al2O3, i.e., an Al2O3 shell layer is coated on the surface of the CCTO@BSCZT core-shell structure. The matrix material includes a polymer, which includes, but is not limited to, one or more of PVDF, P(VDF-HFP), P(VDF-TrFE), PI, and PEI. Accordingly, the flexible dielectric composite membrane is CCTO@BSCZT@Al2O3 / polymer, for example, CCTO@BSCZT@Al2O3 / P(VDF-HFP). It should be noted that in this flexible dielectric composite membrane, the surface of the CCTO@BSCZT core-shell structure can also be coated with other inorganic materials, such as SiO2, thereby forming a CCTO@BSCZT@SiO2 / P(VDF-HFP) composite membrane.

[0070] Please see Figure 13 , Figure 13 This is a schematic flowchart of a method for preparing a flexible dielectric composite film based on CCTO@BSCZT according to an embodiment of the present invention. The preparation method specifically includes the following steps: S1. Disperse the polymer powder in N,N-dimethylformamide and stir until homogeneous to obtain a polymer solution.

[0071] Specifically, weigh out the polymer powder and disperse it in N,N-dimethylformamide (DMF) at a ratio of 0.5g:7ml. Stir for 4-6 hours to obtain a homogeneous polymer solution.

[0072] S2. Disperse the functional filler into the above polymer solution and then sonicate and stir it sequentially to obtain a mixed suspension. The functional filler includes CCTO@BSCZT powder or CCTO@BSCZT@Al2O3 powder.

[0073] Specifically, 0.1g of CCTO@BSCZT powder or CCTO@BSCZT@AlO3 powder is dispersed in a polymer solution, followed by ultrasonic treatment for 60-99 min and stirring for 12-14 h to ensure that the powder is fully and uniformly dispersed to obtain a mixed suspension.

[0074] S3. Using a mixed suspension, a heated coating machine is used to prepare a nanofilm, and the nanofilm is then subjected to vacuum drying, quenching and peeling to obtain a CCTO@BSCZT / polymer composite film or a CCTO@BSCZT@Al2O3 / polymer composite film.

[0075] Specifically, a mixed suspension is used to prepare nanofilms using a heated coating machine. The prepared nanofilms are then dried in a vacuum oven at 60-70°C for 4-6 hours. Finally, the nanofilms are quenched at 200°C for 7-10 minutes, and then immediately quenched with ice water to completely peel the nanofilms off the glass slide, yielding either a CCTO@BSCZT / polymer composite film or a CCTO@BSCZT@Al2O3 / polymer composite film.

[0076] To facilitate understanding of the present invention, the following examples are provided.

[0077] Example 9 The CCTO@BSCZT(0.25:1) / P(VDF-HFP) composite membrane was prepared using a heated coating machine, including the following steps: S1. Weigh 0.5g of P(VDF-HFP) powder and disperse it in 7ml of DMF. Stir for 4h to obtain a uniform P(VDF-HFP) solution.

[0078] S2. Disperse 0.1g of CCTO@BSCZT (0.25:1) powder into P(VDF-HFP) solution, then sonicate for 99min, and stir for 12h to ensure that the powder is fully and uniformly dispersed to obtain a mixed suspension.

[0079] S3. Using a mixed suspension, a heated coating machine was used to prepare nanofilms. The prepared nanofilms were then dried in a vacuum oven at 70°C for 6 hours. Finally, the nanofilms were quenched at 200°C for 7 minutes, and then immediately ice water was poured on them to completely peel the nanofilms off the glass slide, obtaining a CCTO@BSCZT(0.25:1) / P(VDF-HFP) composite film.

[0080] Example 10 A CCTO@BSCZT(0.5:1) / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 9 is that the powder in S2 is CCTO@BSCZT(0.5:1), while the other conditions are the same.

[0081] Example 11 A CCTO@BSCZT(1:1) / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 9 is that the powder in S2 is CCTO@BSCZT(1:1), while the other conditions are the same.

[0082] Example 12 A CCTO@BSCZT(2:1) / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 9 is that the powder in S2 is CCTO@BSCZT(2:1), while the other conditions are the same.

[0083] The composite films of Examples 9 to 12 were subjected to characterization tests, dielectric property tests, and energy storage performance tests; the characterization test results can be found in [link to relevant documentation]. Figure 14~Figure 16 The area of ​​the silver electrode used in the dielectric property test sample was 12.56 mm². 2 The test frequency was 100Hz-1MHz. Please refer to the test results. Figure 17~Figure 18 The energy storage performance was tested using a ferroelectric analyzer to systematically characterize the flexible dielectric composite membrane. The Au electrode area was 3.14 mm². 2 The test frequency was 10Hz. Please refer to the test results. Figure 19~Figure 20 .

[0084] Figure 14 XRD patterns of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios. 2 θ =18.4° corresponds to α-P(VDF-HFP), 2 θ =20.8° corresponds to β-P(VDF-HFP). After CCTO@BSCZT was filled into the P(VDF-HFP) matrix, CCTO(2) could be clearly observed in the composite film. θ =34.5° corresponds to (220) peak) and BSCZT (2 θ =32.2° corresponds to the characteristic peak of (110) and no impurity phase is generated, indicating that the CCTO@BSCZT / P(VDF-HFP) composite membrane was successfully prepared.

[0085] Figure 15 SEM images of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios are shown. (a), (b), (c), and (d) correspond to CCTO@BSCZT(0.25:1) / P(VDF-HFP), CCTO@BSCZT(0.5:1) / P(VDF-HFP), CCTO@BSCZT(1:1) / P(VDF-HFP), and CCTO@BSCZT(2:1) / P(VDF-HFP), respectively. Overall, the CCTO@BSCZT nanofiller is relatively uniformly distributed in the composite membrane, with a small amount of slight agglomeration. No large pores were observed on the membrane surface.

[0086] Figure 16 FTIR spectra of CCTO@BSCZT / P(VDF-HFP) composite membranes with different filler ratios. (1402, 872, and 840 cm⁻¹)-1 The characteristic peak at 1213 cm⁻¹ is attributed to β-P(VDF-HFP). -1 The characteristic peak at α-P(VDF-HFP) corresponds to γ-P(VDF-HFP). α-P(VDF-HFP) peaks at 760, 610, and 484 cm⁻¹ correspond to γ-P(VDF-HFP). -1 Three distinct absorption peaks were observed. β-P(VDF-HFP) dominated in CCTO@BSCZT / P(VDF-HFP).

[0087] Figure 17 The dielectric constant ε of CCTO@BSCZT / P(VDF-HFP) composite film at different frequencies r And the trend of dielectric loss tanδ, where (a) is ε r (b) shows the variation of tanδ with frequency, and (c) shows the ε of the composite film at 1 kHz. r The graph shows the trend of tanδ as the filler content increases. (Example: ...) Figure 17 As shown in (a), due to the polymer matrix itself ε r The dielectric constant is relatively low. When a high dielectric constant filler is added to P(VDF-HFP), the filler can effectively improve the composite membrane. ε r With the addition of fillers, the composite membrane... ε r The frequency response follows a conventional variation pattern. For example... Figure 17 As shown in (c), at 1 kHz, the composite film... ε r The values ​​were 12.66, 14.12, 15.89, and 17.19, respectively, indicating that the introduction of CCTO@BSCZT increased the polarization intensity of the composite film, ultimately leading to the composite film's... ε r Significant improvements were achieved. Meanwhile, such as Figure 17 As shown in (b) and (c), the dielectric loss tan φ increases with increasing CCTO content. δ Gradually increasing. At 1 kHz, the tandem flux of the composite film increases in order of increasing CCTO ratio. δ The values ​​were 0.040, 0.042, 0.054, and 0.066, respectively. Among them, CCTO@BSCZT(0.5:1) / P(VDF-HFP) showed better overall performance. A lower CCTO ratio resulted in fewer leakage paths and lower losses. However, an excessively high CCTO ratio, although... ε r Significant improvement, but increased leakage conductivity due to the exposure of some CCTO particles causes tan... δ A surge.

[0088] This embodiment explains the mechanism of dielectric property changes in the composite film. Based on the band positions of CCTO and BSCZT, CCTO@BSCZT forms a type II heterostructure. The relative band positions, plotted based on the valence band position and band gap, are shown below. Figure 18 As shown. The CCTO band gap is 1.98 eV. E VB Located at 0.8 eV, the BSCZT band gap is 3.32 eV. E VB Located at 2.2 eV. On one hand, when an external electric field is applied, more voltage drops onto the BSCZT, leading to increased polarization of the BSCZT and thus enhancing the polarization intensity of the flexible composite dielectric. On the other hand, in CCTO@BSCZT, electrons migrate from the conduction band of CCTO to BSCZT, while holes migrate from the valence band of BSCZT to CCTO, resulting in space charge separation. Under the influence of the external electric field, these electrons and holes move in opposite directions, further promoting polarization. These dual effects significantly improve the polarization intensity and dielectric properties of the flexible dielectric composite film.

[0089] Figure 19 The Weibull distribution and breakdown field strength diagrams of the CCTO@BSCZT / P(VDF-HFP) composite membrane are shown in (a) and (b). According to the Weibull distribution, the breakdown strength of the composite membrane first increases and then decreases with increasing CCTO content in CCTO@BSCZT. CCTO@BSCZT(0.5:1) / P(VDF-HFP) exhibits a peak Weibull breakdown strength of 320.8 MV / m.

[0090] Figure 20 To investigate the effects of different filler ratios on CCTO@BSCZT / P(VDF-HFP) composite membranes in Weibull E b Next test P-E The curves, calculated, show the usable energy storage densities of the composite membranes CCTO@BSCZT(0.25:1) / P(VDF-HFP), CCTO@BSCZT(0.5:1) / P(VDF-HFP), CCTO@BSCZT(1:1) / P(VDF-HFP), and CCTO@BSCZT(2:1) / P(VDF-HFP). W rec The values ​​were 21.8 J / cm. 3 25.5 J / cm 3 22.3 J / cm 3 and 21.4 J / cm 3 Energy storage efficiency ηThe percentages were 64.3%, 63.4%, 62.8%, and 61.7%, respectively. When the CCTO:BSCZT ratio was 0.5:1, the composite membrane... W rec and η The optimal value was achieved. This indicates that constructing a type II heterogeneous structure packing is an effective measure to improve the energy storage performance of composite membranes.

[0091] Example 13 The CCTO@BSCZT(0.25:1)@Al2O3 / P(VDF-HFP) composite membrane was prepared using a heated coating machine, including the following steps: S1. Weigh 0.5g of P(VDF-HFP) powder and disperse it in 7ml of DMF. Stir for 4h to obtain a uniform P(VDF-HFP) solution.

[0092] S2. Disperse 0.1g of CCTO@BSCZT(0.25:1)@Al2O3 powder into P(VDF-HFP) solution, then sonicate for 99min, and stir for 12h to ensure that the powder is fully and uniformly dispersed to obtain a mixed suspension.

[0093] S3. Using a mixed suspension, a heated coating machine was used to prepare nanofilms. The prepared nanofilms were then dried in a vacuum oven at 70°C for 6 hours. Finally, the nanofilms were quenched at 200°C for 7 minutes, and then immediately ice water was poured on them to completely peel the nanofilms off the glass slide, obtaining a CCTO@BSCZT(0.25:1)@Al2O3 / P(VDF-HFP) composite film.

[0094] Example 14 A CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 13 is that the powder in S2 is CCTO@BSCZT(0.5:1)@Al2O3, while the other conditions are the same.

[0095] Example 15 A CCTO@BSCZT(1:1)@Al2O3 / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 13 is that the powder in S2 is CCTO@BSCZT(1:1)@Al2O3, while the other conditions are the same.

[0096] Example 16 A CCTO@BSCZT(2:1)@Al2O3 / P(VDF-HFP) composite membrane was prepared using a heated coating machine. The difference from Example 13 is that the powder in S2 is CCTO@BSCZT(2:1)@Al2O3, while the other conditions are the same.

[0097] The composite films of Examples 13 to 16 were subjected to characterization tests, dielectric property tests, and energy storage performance tests. The characterization test results can be found in [link to relevant documentation]. Figure 21~Figure 23 Please refer to the dielectric performance test results. Figure 24~Figure 25 Please refer to the energy storage performance test results. Figure 26~Figure 27 The dielectric performance test and energy storage performance test conditions are the same as those described above, and will not be repeated here.

[0098] Figure 21 XRD patterns of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membranes with different filler ratios. 2 θ =18.4° corresponds to α-P(VDF-HFP), 2 θ =20.8° corresponds to β-P(VDF-HFP). After CCTO@BSCZT was filled into the P(VDF-HFP) matrix, CCTO(2) could be observed in the composite film. θ =34.5° corresponds to (220) peak) and BSCZT (2 θ =32.2° corresponds to the characteristic peak of (110) and no impurity phase is generated, indicating that the CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membrane was successfully prepared.

[0099] Figure 22 SEM images of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membranes with different filler ratios are shown. (a), (b), (c), and (d) correspond to CCTO@BSCZT(0.25:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(1:1)@Al2O3 / P(VDF-HFP), and CCTO@BSCZT(2:1)@Al2O3 / P(VDF-HFP), respectively. It can be clearly seen that the membrane surface is relatively dense, the filler is evenly distributed in the composite membrane, and there is a small amount of agglomeration.

[0100] Figure 23 The image shows the FTIR spectrum of the CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite film. In the figure, 1402, 872, and 840 cm⁻¹ are... -1 The characteristic peak at 1213 cm⁻¹ belongs to β-P(VDF-HFP). -1 The characteristic peaks correspond to γ-P(VDF-HFP). At 760, 610, and 484 cm⁻¹... -1Three peaks of α-P(VDF-HFP) can be observed. In the composite material CCTO@BSCZT@Al2O3 / P(VDF-HFP), β-P(VDF-HFP) is dominant.

[0101] Figure 24 The figures show the dielectric properties of CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite films with different ratios, where (a) represents the dielectric constant. ε r The graph shows the change with frequency, and (b) represents the dielectric loss tan φ. δ The graph shows the frequency variation of the composite film at 1 kHz. ε r and tan δ The trend of change with increasing filler content.

[0102] like Figure 24 As shown in (a), at 1 kHz, ε r As the ratio of CCTO to BSCZT gradually increased from 0.25:1 to 2:1, the CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite film at 1 kHz... ε r like Figure 24 As shown in (c), CCTO is ordered from low to high. ε r The values ​​were 15.05, 16.74, 17.65, and 19.14, respectively. Combined with SEM morphology ( Figure 22 The introduction of the Al2O3 coating effectively suppressed filler agglomeration. At a low ratio of 0.25:1, ε r The polarization effect is relatively low; when the ratio increases to 0.5:1, the polarization effect strengthens. ε r Significant increase; at 2:1 ε r It reached 19.14.

[0103] Meanwhile, the dielectric loss tan of the composite film at a frequency of 1kHz is... δ The trend shows a slight decrease followed by an increase with increasing CCTO content. The composite membranes CCTO@BSCZT(0.25:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(1:1)@Al2O3 / P(VDF-HFP), and CCTO@BSCZT(2:1)@Al2O3 / P(VDF-HFP) exhibit tandem voltage at 1 kHz. δThe values ​​were 0.036, 0.034, 0.046, and 0.052, respectively. Compared with the uncoated Al2O3 CCTO@BSCZT / P(VDF-HFP) composite membrane, the tandem thickness of CCTO@BSCZT@Al2O3 / P(VDF-HFP) was significantly higher. δ All decreased. Among them, the composite membrane CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP) showed better performance.

[0104] Figure 25 This diagram illustrates the polarization mechanism of CCTO@BSCZT@Al2O3 / P (VDF-HFP). The energy level difference between the different materials and interfacial interactions jointly regulate charge behavior and polarization response. CCTO has a narrower band gap, while BSCZT has a wider band gap. This energy level difference drives electrons to concentrate on the BSCZT side and holes to concentrate on the CCTO side, improving the polarization effect of the composite film. Al2O3 acts as a charge-blocking layer, providing deep traps to capture free electrons and reducing leakage current and dielectric loss. δ .

[0105] Figure 26 The figures show the Weibull distribution and breakdown field strength of the CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membrane, where (a) is the Weibull distribution and (b) is the breakdown field strength. As shown in the figure, the breakdown field strength of the composite membrane increases with the increase of the proportion of CCTO in CCTO@BSCZT. E b The trend shows an initial increase followed by a decrease. CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP) has a peak Weibull breakdown strength of 417.6 MV / m.

[0106] Figure 27 The CCTO@BSCZT@Al2O3 / P(VDF-HFP) composite membrane under breakdown field strength P-E Curves. Calculations show that the composite membranes CCTO@BSCZT(0.25:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP), CCTO@BSCZT(1:1)@Al2O3 / P(VDF-HFP), and CCTO@BSCZT(2:1)@Al2O3 / P(VDF-HFP) exhibit [various characteristics]. W rec The values ​​were 29.3 J / cm. 3 39.8 J / cm 3 36.4 J / cm 3 and 30.2 J / cm 3 , ηThe percentages were 68.2%, 70.7%, 69.7%, and 68.7%, respectively. The results show that the energy storage performance of the composite membrane first increases and then decreases with increasing CCTO ratio. When the CCTO:BSCZT ratio in the filler CCTO@BSCZT@Al2O3 is 0.5:1, the energy storage density and energy storage efficiency of the prepared composite membrane reach their optimal values.

[0107] In this embodiment, based on the improvement of the polarization intensity of the composite membrane by CCTO@BSCZT, Al2O3 is used as a barrier layer to reduce leakage current and dielectric loss, thereby improving the energy storage performance of the composite membrane.

[0108] Example 3 Building upon Examples 1 and 2, this embodiment provides a flexible dielectric composite membrane based on CCTO@BSCZT. This flexible dielectric composite membrane is a multilayer composite membrane. Compared to single-layer membranes, multilayer composite membranes effectively enhance energy storage performance and improve the reliability of the composite membrane by assigning specific functions to each layer. This embodiment employs an asymmetric three-layer membrane structure. The rational combination of the bottom layer, transition layer, and polarization layer not only improves the dielectric constant and polarization performance but also enhances the breakdown strength, thereby improving the overall performance of the composite membrane.

[0109] Please see Figure 28 , Figure 28 This is a schematic diagram of the structure of a multilayer composite membrane provided in an embodiment of the present invention. The multilayer composite membrane includes a bottom layer, a transition layer, and a polarization layer stacked sequentially. Specifically, the bottom layer is made of a polymer, wherein the polymer includes, but is not limited to, one or more of PVDF, P(VDF-HFP), P(VDF-TrFE), PI, and PEI; the transition layer is made of BSCZT-Y@BSCZT-Mn@Al2O3 / polymer; the polarization layer is made of CCTO@BSCZT@Al2O3 / polymer; correspondingly, the multilayer composite membrane is CCTO@BSCZT@Al2O3-polymer / BSCZT-Y@BSCZT-Mn@Al2O3-polymer / polymer. The polymer includes, but is not limited to, one or more of PVDF, P(VDF-HFP), P(VDF-TrFE), PI, and PEI. For example, the polymer used is P(VDF-HFP), and the multilayer composite film is CCTO@BSCZT@Al2O3-P(VDF-HFP) / BSCZT-Y@BSCZT-Mn@Al2O3-P(VDF-HFP) / P(VDF-HFP) (abbreviated as CBAP / YMAP / P).

[0110] It should be noted that the mass ratio of BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler and CCTO@BSCZT@Al2O3 functional filler to the polymer in the transition layer and polarization layer can be determined according to the performance requirements of the composite membrane. Specifically, in the transition layer, the mass of BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler can be 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc., of the polymer mass; preferably, this mass ratio is 1~4wt%, and more preferably, this mass ratio is 3wt%. In the polarization layer, the mass of CCTO@BSCZT@Al2O3 functional filler can be 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc., of the polymer mass; preferably, this mass ratio is 1~4wt%, and more preferably, this mass ratio is 3wt%.

[0111] This embodiment also provides a method for preparing a multilayer composite film based on CCTO@BSCZT. Taking CBAP / YMAP / P as an example, the method uses a layer-by-layer casting method to prepare the multilayer composite film, and specifically includes the following steps: S1. Dissolve P(VDF-HFP) in DMF and stir until homogeneous to obtain a polymer solution.

[0112] Specifically, P(VDF-HFP) is dissolved in DMF and magnetically stirred at room temperature for 4-5 hours to obtain a polymer solution; the polymer solution is then divided into three portions for later use.

[0113] S2. The polymer solution is cast into a film using a casting method to obtain the bottom layer.

[0114] Specifically, the first polymer solution is cast into a film at 60-80°C to form a P(VDF-HFP) underlayer with a thickness of 5-6 μm.

[0115] S3. Add BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler to the polymer solution and stir until homogeneous. Then, cast the filler onto the substrate using a casting method to obtain a BSCZT-Y@BSCZT-Mn@Al2O3 / P(VDF-HFP) transition layer.

[0116] Specifically, BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler was added to the second polymer solution, wherein the content of Y was 0.3 mol%, the content of Mn was 1~4 mol%, and the mass of BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler was 1~4 wt% of the mass of P(VDF-HFP) polymer; then the mixture was magnetically stirred at room temperature for 8~12 h, and then cast into a film at 60~80 °C to form a YMAP transition layer with a thickness of 7~8 μm.

[0117] S4. Add CCTO@BSCZT@Al2O3 functional filler to the polymer solution and stir evenly. Then, cast the film on the transition layer by casting method to obtain CCTO@BSCZT@Al2O3 / P(VDF-HFP) polarization layer, forming a multilayer nanocomposite film. Specifically, CCTO@BSCZT@Al2O3 functional filler was added to the third polymer solution, wherein the mass of CCTO@BSCZT@Al2O3 functional filler was 1~4wt% of the mass of P(VDF-HFP) polymer; then the mixture was magnetically stirred at room temperature for 8-12 hours, and then cast into a film at 60~80°C to form a CBAP polarized layer with a thickness of 6~7μm.

[0118] S5. The multilayer nanocomposite film is subjected to vacuum drying, quenching and peeling in sequence to obtain a multilayer composite film based on CCTO@BSCZT.

[0119] Specifically, the prepared multilayer nanocomposite film is dried in a vacuum oven at 60-70°C for 4-8 hours. After quenching the multilayer nanocomposite film at 200°C for 7-10 minutes, ice water is immediately poured on it to completely peel the film off the glass slide, thus obtaining the CBAP / YMAP / P multilayer composite film.

[0120] To facilitate understanding of the present invention, the following examples are provided.

[0121] Example 17 Using BSCZT-Y@BSCZT-Mn3@Al2O3 as the transition layer (Mn3 refers to a Mn content of 3 mol%) and CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP) as the polarization layer, a CBAP / YMAP / P multilayer composite film was prepared by a layer-by-layer casting method, including the following steps: S1. Dissolve P(VDF-HFP) in DMF and stir magnetically at room temperature for 5 hours to obtain a polymer solution; divide the polymer solution into three portions for later use.

[0122] S2. Cast the first polymer solution into a film at 70°C to form a P(VDF-HFP) underlayer with a thickness of 5.5 μm.

[0123] S3. Add BSCZT-Y@BSCZT-Mn3@Al2O3 ceramic filler to the second polymer solution, wherein the content of Y is 0.3 mol%, the content of Mn is 3 mol%, and the mass of BSCZT-Y@BSCZT-Mn@Al2O3 ceramic filler is 3 wt% of the mass of P(VDF-HFP) polymer; then stir magnetically at room temperature for 12 h, and then cast into a film at 70°C to form a YMAP transition layer with a thickness of 7.5 μm.

[0124] S4. Add CCTO@BSCZT(0.5:1)@Al2O3 functional filler to the third polymer solution, wherein the mass of CCTO@BSCZT@Al2O3 functional filler is 3wt% of the mass of P(VDF-HFP) polymer; then stir magnetically at room temperature for 12h, and then cast into a film at 70°C to form a CBAP polarized layer with a thickness of 6.5 μm.

[0125] S5. The prepared multilayer nanocomposite film was dried in a vacuum oven at 70°C for 6 hours. After quenching the multilayer nanocomposite film at 200°C for 7 minutes, ice water was immediately poured on it to completely peel the film off the glass slide, obtaining the CBAP / YMAP / P multilayer composite film.

[0126] Characterization tests, dielectric property tests, and energy storage performance tests were performed on the multilayer composite film of Example 17. The characterization test results can be found in [link to relevant documentation]. Figure 29~Figure 30 Please refer to the dielectric performance test results. Figure 31 Please refer to Table 1 for the energy storage performance test results. Figure 32 And Table 2.

[0127] Figure 29 XRD pattern of CBAP / YMAP / P multilayer composite film. 2 θ =18.4° corresponds to α-P(VDF-HFP), 2 θ =20.8° corresponds to β-P(VDF-HFP), and CCTO (2) can be clearly observed in the composite membrane. θ =34.5° corresponds to (220) peak) and BSCZT (2 θ =32.2° corresponds to the characteristic peak of (110) and no impurity phase is generated, indicating that the CBAP / YMAP / P composite membrane was successfully prepared.

[0128] Figure 30The images show the SEM image and EDS spectrum of the cross-section of the CBAP / YMAP / P multilayer composite film. The film surface is dense and smooth. The filler is relatively uniformly distributed throughout the composite film, with some slight agglomeration. EDS clearly shows the elemental distribution: for example, Sr is mainly concentrated in the middle and upper layers, while Cu is only present in the upper layer. This difference in elemental distribution clearly delineates the boundaries of the film layers, highly consistent with experimental expectations, strongly demonstrating the successful fabrication of the multilayer film.

[0129] Figure 31 For CBAP / YMAP / P multilayer composite membrane ε r and tan δ The frequency-dependent graph shows that the polarization response is rapid at lower frequencies. ε r Higher; at higher frequencies, the polarization response speed slows down, leading to ε r The decline. At 1 kHz, the composite membrane's... ε r It is 15.13, tan δ It is 0.045.

[0130] Table 1 compares the dielectric properties of the multilayer composite film with those of CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP), BSCZT-Y@BSCZT-Mn3@Al2O3 / P(VDF-HFP), and P(VDF-HFP). As shown in Table 1, the dielectric constant of the multilayer composite film... ε r The dielectric loss is significantly higher than that of P(VDF-HFP), higher than that of BSCZT-Y@BSCZT-Mn3@Al2O3 / P(VDF-HFP), and slightly lower than that of CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP). The dielectric loss tan... δ It increased slightly compared to P(VDF-HFP), but remained below 0.05.

[0131] Table 1

[0132] Figure 32 Weibull distribution diagram of CBAP / YMAP / P composite membrane and E b Below P-E Curve. The CBAP / YMAP / P curve is obtained based on the Weibull distribution. E b It is 456.1 MV / m, according to P-E The curve is obtained Wrec 41.2 J / cm 3 , η It is 68.8%.

[0133] Table 2 compares the energy storage performance of CBAP / YMAP / P with CCTO@BSCZT(0.5:1)@Al2O3 / P(VDF-HFP), BSCZT-Y@BSCZT-Mn3@Al2O3 / P(VDF-HFP), and P(VDF-HFP). CBAP / YMAP / P exhibits the highest energy storage performance. E b and W rec It performs better in withstanding high electric fields and energy storage, which creates opportunities for manufacturing large-capacity capacitors for different field strength conditions.

[0134] Table 2

[0135] The multilayer composite film in this embodiment adopts an asymmetric three-layer film structure consisting of a bottom layer, a transition layer, and a polarization layer. This structure not only enhances the dielectric constant and improves the breakdown strength of the composite film, but also ensures its mechanical flexibility, meeting the demand for high-performance flexible dielectric materials in complex working environments.

[0136] Example 4 Based on Embodiments 2 and 3, this embodiment provides an application of the flexible dielectric composite film based on CCTO@BSCZT described in Embodiments 2 or 3 as a flexible dielectric film in an energy storage capacitor.

[0137] Specifically, the flexible dielectric film, as the core functional medium of the energy storage capacitor, is sandwiched between two metal electrodes as a functional layer. Energy storage capacitors are core components in various circuits, with wide-ranging applications covering diverse fields: from small everyday appliances and portable wearable devices to large-scale power grid transmission and transformation systems, wind and photovoltaic power generation converters, high-speed rail and EMU traction systems, new energy vehicle ignition devices, and even electromagnetic catapult systems, all rely on energy storage capacitors to play a crucial role in energy storage and release. Generally, flexible dielectric films are used in a wound manner, such as biaxially oriented polypropylene, for preparing thin-film capacitors. The flexible dielectric composite film prepared in this embodiment has high dielectric constant and energy storage density, and can replace traditional BOPP dielectrics in the preparation of thin-film capacitors. Simultaneously, flexible dielectric capacitors that do not require winding can also be developed, thus providing new opportunities for the development and manufacturing of flexible devices.

[0138] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A functional filler based on CCTO@BSCZT, characterized in that, include: CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 core-shell structure, in which CaCu3Ti4O 12 with Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 forms a type II heterojunction through band matching.

2. The functional filler based on CCTO@BSCZT according to claim 1, characterized in that, The CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The surface of the O3 core-shell structure is coated with an Al2O3 shell, forming CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3.

3. The functional filler based on CCTO@BSCZT according to claim 1 or 2, characterized in that, CaCu3Ti4O 12 with Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The molar ratio of O3 is (0.25~2):

1.

4. A method for preparing a functional filler based on CCTO@BSCZT, characterized in that, Including the following steps: According to Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The stoichiometric ratio of O3 is determined by weighing barium acetate, calcium acetate, and strontium acetate and adding them to a mixed solution of glacial acetic acid and deionized water. After stirring evenly, the first solution is obtained. Tetrabutyl titanate, zirconium n-butoxide, and acetylacetone were added to a mixed solution of glacial acetic acid and anhydrous ethanol, and stirred until homogeneous to obtain a second solution. The first solution is added dropwise to the second solution, and the mixture is stirred to form a sol. CaCu3Ti4O 12 The powder is added to the sol and stirred for a period of time, and then stirred under heating conditions to form a gel; The gel was dried and ground, then mixed with an aqueous sodium hydroxide solution. A hydrothermal reaction was then carried out to obtain the product. Finally, the product was washed and dried to obtain CaCu3Ti4O. 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 powder, including CaCu3Ti4O 12 with Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 forms a type II heterojunction through band matching.

5. The method for preparing the functional filler based on CCTO@BSCZT according to claim 4, characterized in that, It also includes the following steps: Weigh the CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 powder was added to deionized water and anhydrous ethanol, and then sonicated and stirred to obtain a suspension. Weigh aluminum nitrate and add it to deionized water, stirring until homogeneous to obtain the third solution; The third solution was poured into the suspension and stirred. The pH of the mixed solution was then adjusted to 9-10, and stirring was continued for a period of time. After centrifugation, washing, and drying, the solution was calcined to obtain CaCu3Ti4O. 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 powder.

6. A flexible dielectric composite membrane based on CCTO@BSCZT, characterized in that, The flexible dielectric composite membrane comprises functional fillers and a matrix material, wherein... The functional filler includes CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 core-shell structure, CaCu3Ti4O 12 with Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 forms a type II heterojunction through band matching; The matrix material includes a polymer, which includes one or more of PVDF, P(VDF-HFP), P(VDF-TrFE), PI, and PEI; Accordingly, the flexible dielectric composite film is CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3 / polymer.

7. The flexible dielectric composite membrane based on CCTO@BSCZT according to claim 6, characterized in that, The CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The surface of the O3 core-shell structure is coated with an Al2O3 shell, forming CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 functional filler; Accordingly, the flexible dielectric composite film is CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 / polymer.

8. The flexible dielectric composite membrane based on CCTO@BSCZT according to claim 7, characterized in that, The flexible dielectric composite film is a multilayer composite film, which includes a bottom layer, a transition layer, and a polarization layer stacked sequentially. The underlying material includes a polymer. The material of the transition layer includes Ba. 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3-Y@ Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3-Mn@Al2O3 / polymer; The polarization layer is made of CaCu3Ti4O. 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3@Al2O3 / polymer.

9. The flexible dielectric composite membrane based on CCTO@BSCZT according to claim 8, characterized in that, In the transition layer, Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 O3-Y@ Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The mass of the O3-Mn@Al2O3 ceramic filler is 1~4 wt% of the mass of the polymer. In the polarization layer, CaCu3Ti4O 12 @Ba 0.34 Sr 0.51 Ca 0.15 Zr 0.1 Ti 0.9 The mass of the O3@Al2O3 functional filler is 1~4 wt% of the polymer mass. The thickness of the bottom layer is 5-6 μm; the thickness of the transition layer is 7-8 μm; and the thickness of the polarization layer is 6-7 μm.

10. The application of a flexible dielectric composite film based on CCTO@BSCZT as described in any one of claims 6-9 in an energy storage capacitor.

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