High-entropy ceramic / polymer composite dielectric film and preparation method and application thereof

Abstract

The invention discloses a high-entropy ceramic / polymer composite dielectric film and a preparation method and application thereof. The preparation method comprises the steps that S1, a hydrothermal method is adopted, proportioning is conducted according to the structural general formula (K0. 5Bi0. 5) (FexNbxTi1-2x) O3, KBFNT powder is prepared, and x is larger than or equal to 0 and smaller than or equal to 1 / 3; s2, forming a PDA shell layer on the outer side of the KBFNT to obtain KBFNT coated PDA powder; s3, mixing the KBFNT coated PDA powder and an organic polymer according to a mass ratio of (2.5%-10%): 1 to obtain a KBFNT coated PDA coated organic polymer; s4, preparing a high-entropy ceramic / polymer composite dielectric film comprising at least one layer of dielectric film; at least one layer of the dielectric film comprises a KBFNT (PDA) organic polymer. The composite dielectric film has high breakdown field strength, high energy storage density and high charge-discharge efficiency, and can be used for capacitors and high-power electrostatic energy storage equipment.

Description

Technical Field

[0001] This invention belongs to the field of capacitor composite dielectric film technology, specifically relating to a high-entropy ceramic / polymer composite dielectric film, its preparation method, and its application. Background Technology

[0002] As a fundamental component of circuits, capacitors have faced increasing demands for miniaturization and weight reduction due to advancements in information technology. Dielectric capacitors, characterized by high power density and rapid discharge, play a crucial role as energy storage elements in fields such as electric vehicles, aerospace, and medical devices. The core technical indicators for evaluating dielectric capacitors are energy density and discharge speed. High energy density and rapid discharge are the high-performance metrics sought after in dielectric capacitors.

[0003] Traditional commercial film capacitors typically use biaxially oriented polypropylene (BOPP) dielectric. However, due to the low dielectric constant of BOPP, even with a high electric field strength of 700 MV / m, the energy storage density of the capacitor remains very low (<2 J / cm²). 3 To achieve large capacitance, the manufactured capacitors are extremely large; on the other hand, BOPP has limited heat resistance and is unsuitable for use in high-temperature environments above 105°C. Therefore, researchers have developed ceramic-filled polymer composite dielectrics. High-melting-point polymer dielectrics such as polyvinylidene fluoride (PVDF) and polyetherimide (PEI) are used as the matrix to improve temperature resistance and ensure high breakdown field strength. A small amount of ceramic powder is used to fill the polymer dielectric to improve the dielectric constant. However, due to the slow domain flipping speed and insufficient effective polarization of ordinary ceramic powder, the energy density of the prepared composite dielectric film is still relatively low, and the energy density decreases significantly with increasing temperature. Furthermore, it is difficult to achieve nanoscale rapid discharge.

[0004] Therefore, how to provide a high-energy-density composite dielectric that is suitable for high-temperature applications of thin-film capacitors and can achieve rapid discharge is a technical problem that urgently needs to be solved in this field.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a high-entropy ceramic / polymer composite dielectric thin film, its preparation method, 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 method for preparing a high-entropy ceramic / polymer composite dielectric thin film, comprising the following steps: S1. The original powdered bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K). 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x KBFNT powder was prepared by adding O3 as an ingredient and using a hydrothermal method, wherein 0≤x≤1 / 3; S2. A polydopamine (PDA) shell is formed on the outside of the KBFNT particles of the KBFNT powder to obtain KBFNT@PDA powder; S3. Mix the KBFNT@PDA powder and organic polymer at a mass ratio of (2.5%~10%):1 to obtain a high-entropy ceramic / polymer composite dielectric slurry; S4. Prepare a high-entropy ceramic / polymer composite dielectric film; the high-entropy ceramic / polymer composite dielectric film includes at least one dielectric film; at least one of the dielectric films is prepared using the high-entropy ceramic / polymer composite dielectric slurry.

[0007] In one embodiment of the present invention, step S2 further includes forming an Al2O3 shell before forming the PDA shell, and then forming a PDA shell on the outside of the Al2O3 shell; The formation of the Al2O3 shell includes: The KBFNT powder was dispersed in an ethanol-water solution, sonicated for 20-40 min, and then stirred for 20-40 min to obtain a KBFNT suspension. The KBFNT suspension was mixed with aluminum nitrate solution and stirred for 30–90 min. The pH value was adjusted to 9.0–10.0 with ammonia water, and then stirred for 10–15 h. After centrifugation, washing and drying, the mixture was calcined at 500–800 °C for 1–3 h to obtain KBFNT@Al2O3 powder. The mass ratio of the KBFNT powder to aluminum nitrate was 1:(0.15–0.60).

[0008] In one embodiment of the present invention, the formation of the PDA shell includes: A Tris-HCl buffer solution was prepared, wherein the concentration of the Tris-HCl buffer solution was 0.05–0.2 mol / L and the pH value was 8.0–9.0; The KBFNT@Al2O3 powder was added to the Tris-HCl buffer solution and ultrasonically dispersed at a power of 100-500W for 0.5-2h to obtain a KBFNT@Al2O3 suspension. Dopamine hydrochloride was added to the KBFNT@Al2O3 suspension, and the mixture was ultrasonically dispersed at 100-500W for 0.5-1h. The mixture was then stirred at 20-40℃ for 10-24h, centrifuged, washed, and dried at 50-80℃ for 6-12h to obtain KBFNT@Al2O3@PDA powder.

[0009] In one embodiment of the present invention, step S3 includes: S31. Dissolve the organic polymer in an organic solvent and stir until homogeneous to obtain an organic polymer solution; S32. The KBFNT@PDA powder is ultrasonically dispersed in the organic polymer solution, and after stirring, a high-entropy ceramic / polymer composite dielectric slurry is obtained.

[0010] In one embodiment of the present invention, the organic polymer is PVDF and the organic solvent is DMF, wherein the mass ratio of PVDF to the volume ratio of DMF is 0.5 g: 10.0 mL. Alternatively, the organic polymer is PEI, and the organic solvent is NMP, satisfying a mass ratio of PEI to NMP of 0.5 g: 10.0 mL.

[0011] In one embodiment of the present invention, in step S1, the structural formula (K) 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x In O3, x = 0.1, 0.2, 0.3 or 1 / 3.

[0012] In one embodiment of the present invention, in step S3, the organic polymer is at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoropropylene) copolymer (P(VDF-HFP)), poly(vinylidene fluoride-trifluoroethylene) copolymer (P(VDF-TrFE)), polyimide (PI), and polyetherimide (PEI).

[0013] In one embodiment of the present invention, in step S4, the dielectric film consists of three layers, namely a bottom layer, a middle layer and a top layer stacked sequentially; At least one of the bottom layer, the middle layer, and the top layer is prepared using the high-entropy ceramic / polymer composite dielectric slurry. The thickness of the bottom layer, the middle layer, and the top layer are all in the range of 5~6 μm.

[0014] Secondly, the present invention provides a high-entropy ceramic / polymer composite dielectric thin film, which is prepared by the above-described preparation method.

[0015] Thirdly, the present invention provides an application of the above-mentioned high-entropy ceramic / polymer composite dielectric film in the preparation of high-dielectric energy storage capacitors.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The preparation method provided by this invention involves forming a high-entropy ceramic / polymer composite dielectric film by combining a polymer with a high-entropy ceramic filler KBFNT@Al2O3@PDA dispersed in the polymer. This composite dielectric film has few defects and exhibits high breakdown field strength, high energy storage density, and high charge / discharge efficiency in high-temperature environments, making it a suitable material for capacitors and high-power electrostatic energy storage.

[0017] 2. This invention synthesizes high-entropy ceramics using a hydrothermal method, and then prepares composite dielectric films using a casting method. The preparation method is simple and easy to industrialize.

[0018] 3. In the multilayer composite film of the present invention, the synergistic effect of each layer helps to improve the electric field distribution, reduce the risk of breakdown, and significantly improve the breakdown field strength of the film material. At the same time, the polarization layer further enhances the dielectric constant of the composite film. Therefore, the multilayer composite film can not only improve the dielectric constant, but also enhance the breakdown strength and ensure mechanical flexibility, which can meet the demand for high-performance dielectric materials in complex working environments.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 These are the XRD spectra of the high-entropy ceramic powder KBFNT prepared in Examples 1-5 of this invention; Figure 2 These are SEM characterization images of the high-entropy ceramic powder KBFNT prepared in Examples 1-5 of this invention; Figure 3 These are the particle size statistics of the high-entropy ceramic powder KBFNT prepared in Examples 1-5 of this invention; Figure 4 These are the XRD spectra of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 1-5 of this invention; Figure 5 These are SEM characterization images of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 1-5 of this invention; Figure 6 These are the dielectric property test results of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 1-5 of this invention; Figure 7 These are the energy storage performance test results of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 1-5 of this invention; Figure 8 These are the XRD spectra of KBFNT@Al2O3 prepared in Examples 6-9 of this invention; Figure 9 These are SEM characterization images of KBFNT@Al2O3 prepared in Examples 6-9 of this invention; Figure 10 These are the particle size statistics of KBFNT@Al2O3 prepared in Examples 6-9 of this invention; Figure 11 This is a TEM characterization image of KBFNT@Al2O3 prepared in Example 7 of this invention; Figure 12 This is the HAADF characterization diagram of KBFNT@Al2O3 prepared in Example 7 of this invention; Figure 13 The XRD spectra of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 6-9 of this invention and the PVDF dielectric energy storage films prepared in Comparative Example 1 are shown. Figure 14 These are SEM characterization images of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 6-9 of this invention; Figure 15 These are the dielectric performance test results of the high-entropy ceramic / polymer composite dielectric films prepared in Examples 6-9 of this invention; Figure 16 These are the energy storage performance test results of the high-entropy ceramic / polymer composite dielectric thin films prepared in Examples 6-9 of this invention; Figure 17 (a) shows the XRD patterns of the multilayer composite dielectric films prepared in Examples 10, 12, and 13 of this invention and the three-layer PEI dielectric energy storage film prepared in Comparative Example 3; (b) shows the cross-sectional SEM characterization of the multilayer composite dielectric film prepared in Example 10. Figure 18 (a) shows the dielectric performance test results of the multilayer composite dielectric films prepared in Examples 10, 11, and 13 of this invention, the single-layer PEI dielectric energy storage film prepared in Comparative Example 2, and the three-layer PEI dielectric energy storage film prepared in Comparative Example 3; (b) shows the dielectric performance test results of the multilayer composite dielectric films prepared in Examples 10, 14, and 15; (c) shows the change in dielectric performance of the multilayer composite dielectric film prepared in Example 10 at different temperatures. Figure 19 These are the energy storage performance test results of the multilayer composite dielectric films prepared in Examples 10, 11, and 13 of this invention at room temperature; Figure 20The results show the energy storage performance and charge / discharge performance of the multilayer composite dielectric film prepared in Example 10 of this invention at 150°C. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and specific embodiments, provides a detailed description of a high-entropy ceramic / polymer composite dielectric thin film, its preparation method, and its applications based on the present invention.

[0022] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0023] In this invention, PDA refers to polydopamine, PVDF refers to polyvinylidene fluoride, (P(VDF-HFP) refers to poly(vinylidene fluoride-hexafluoropropylene) copolymer, P(VDF-TrFE) refers to poly(vinylidene fluoride-trifluoroethylene) copolymer, PI refers to polyimide, DMF refers to N,N-dimethylformamide, PEI refers to polyetherimide, NMP refers to N-methylpyrrolidone, and KBFNT refers to (K 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x O3 (x = 0 ~ 1 / 3).

[0024] Example 1 S1. The original powdered bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K). 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x O3 was used as the raw material, where x=0; KBFNT powder was prepared by hydrothermal method.

[0025] Specifically, Bi(NO3)3·5H2O and Fe(NO3)3·9H2O (the mass of Fe(NO3)3·9H2O in Example 1 was 0) were weighed using an electronic balance and added to a 0.2 mol / L nitric acid solution and stirred to dissolve, obtaining a mixed solution. TiO2 and Nb2O5 (the mass of Nb2O5 in Example 1 was 0) were weighed and added to a 12 mol / L potassium hydroxide solution and stirred to form a suspension. The mixed solution was added dropwise to the suspension and stirred for 1 h to form a precursor. The precursor was then transferred to a reaction vessel and hydrothermally reacted at 200°C for 24 h. After the reaction, deionized water and ethanol were added to wash until neutral, and the mixture was dried at 60°C for 12 h and then calcined in a muffle furnace at 850°C for 2 h to obtain KBFNT powder. During the hydrothermal reaction, an ion exchange reaction occurred, transforming the precursor into the solid solution KBFNT. The molar ratio of iron ions, niobium ions, and titanium ions in the KBFNT powder is 0:0:1. The KBFNT powder prepared in this example is defined as KBFNT0 sample.

[0026] S2. A PDA shell is formed on the outside of the KBFNT powder particles to obtain KBFNT@PDA powder. Specifically, this includes: A Tris-HCl buffer solution with a concentration of 0.1 mol / L and a pH of 8.0–9.0 was prepared. KBFNT powder was added to the Tris-HCl buffer solution and ultrasonically dispersed at 200 W for 0.5 h to obtain a KBFNT suspension. Dopamine hydrochloride was added to the KBFNT suspension, and after ultrasonic dispersion at 200 W for 0.5 h, the mixture was stirred at 30 °C for 24 h. After centrifugation, washing, and drying at 60 °C for 12 h, KBFNT@PDA powder was obtained.

[0027] S3. Mix KBFNT@PDA powder and organic polymer PVDF at a mass ratio of 5%:1 to obtain a high-entropy ceramic / polymer composite dielectric slurry.

[0028] Specifically, this includes: using high-entropy ceramics (KBFNT0 sample) and PVDF as raw materials, preparing high-entropy ceramic / polymer composite dielectric films by tape casting.

[0029] 0.5 g of PVDF was uniformly dispersed in 10.0 mL of DMF and stirred until homogeneous to obtain a PVDF solution, which was used to prepare the composite dielectric slurry. High-entropy ceramic (0.025 g of KBFNT0 sample) was ultrasonically dispersed in the PVDF solution and stirred to obtain a KBFNT@PDA / PVDF suspension. This KBFNT@PDA / PVDF suspension is the high-entropy ceramic / polymer composite dielectric slurry containing KBFNT / PVDF.

[0030] S4. 70 μL of KBFNT@PDA / PVDF suspension was uniformly coated onto glass and dried at 60°C for 12 h to remove the solvent. Finally, the resulting film was heated at 200°C for 10 min and then immediately quenched in ice water to obtain a single-layer high-entropy ceramic / polymer composite dielectric film KBFNT@PDA / PVDF. The high-entropy ceramic / polymer composite dielectric film prepared in this embodiment is defined as a KBFNT0 / PVDF film.

[0031] In Example 1, the XRD characterization pattern of the KBFNT0 sample is shown below. Figure 1 See SEM characterization image. Figure 2 (a) See particle size statistics in section (a). Figure 3 (a). XRD characterization of the KBFNT0 / PVDF membrane is shown in Figure (a). Figure 4 See SEM characterization image. Figure 5 (b) The dielectric performance test results are shown in [reference]. Figure 6 See energy storage performance results. Figure 7 .

[0032] Example 2 The difference between this embodiment and Embodiment 1 is as follows: In step S1, the original powder materials bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K... 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x O3 was used as the raw material, where x=0.1; KBFNT powder was prepared by hydrothermal method. That is, the molar ratio of iron ions, niobium ions and titanium ions in the KBFNT powder is 0.1:0.1:0.8. The KBFNT powder prepared in this example is defined as KBFNT1 sample.

[0033] In step S2, a PDA shell is formed on the outside of the KBFNT particles in the KBFNT1 sample. Other specific processes are the same as step S2 in Example 1.

[0034] In step S3, 0.025g of KBFNT1 sample is taken, and the other specific procedures are the same as step S3 in Example 1.

[0035] In step S4, the same as step S4 in Example 1, the high-entropy ceramic / polymer composite dielectric film prepared in this example is defined as KBFNT1 / PVDF film.

[0036] In Example 2, the XRD characterization pattern of the KBFNT1 sample is shown below. Figure 1 See SEM characterization image. Figure 2 (b) See particle size statistics in section (b). Figure 3(b) XRD characterization of the KBFNT1 / PVDF membrane is shown in Figure [reference needed]. Figure 4 See SEM characterization image. Figure 5 (c) The dielectric performance test results are shown in [reference]. Figure 6 See energy storage performance results. Figure 7 .

[0037] Example 3 The difference between this embodiment and Embodiment 1 is as follows: In step S1, the original powder materials bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K... 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x O3 was used as the raw material, where x=0.2; KBFNT powder was prepared by hydrothermal method. That is, the molar ratio of iron ions, niobium ions and titanium ions in the KBFNT powder was 0.2:0.2:0.6. The KBFNT powder prepared in this example is defined as KBFNT2 sample.

[0038] In step S2, a PDA shell is formed on the outside of the KBFNT particles in the KBFNT2 sample. Other specific processes are the same as step S2 in Example 1.

[0039] In step S3, 0.025g of KBFNT2 sample is taken, and the other specific procedures are the same as step S3 in Example 1.

[0040] In step S4, the same as step S4 in Example 1, the high-entropy ceramic / polymer composite dielectric film prepared in this example is defined as KBFNT2 / PVDF film.

[0041] In Example 3, the XRD characterization pattern of the KBFNT2 sample is shown below. Figure 1 See SEM characterization image. Figure 2 (c) See particle size statistics for [reference]. Figure 3 (c) XRD characterization of the KBFNT2 / PVDF membrane is shown in [reference]. Figure 4 See SEM characterization image. Figure 5 (d) The dielectric performance test results are shown in [reference]. Figure 6 See energy storage performance results. Figure 7 .

[0042] Example 4 The difference between this embodiment and Embodiment 1 is as follows: In step S1, the original powder materials bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K... 0.5 Bi 0.5 (Fe) xNb x Ti 1-2x O3 was used as the raw material, where x=0.3; KBFNT powder was prepared by hydrothermal method. That is, the molar ratio of iron ions, niobium ions and titanium ions in the KBFNT powder was 0.3:0.3:0.4. The KBFNT powder prepared in this example is defined as KBFNT3 sample.

[0043] In step S2, a PDA shell is formed on the outside of the KBFNT particles in the KBFNT3 sample. Other specific processes are the same as step S2 in Example 1.

[0044] In step S3, 0.025g of KBFNT3 sample is taken, and the other specific procedures are the same as step S3 in Example 1.

[0045] In step S4, the same as step S4 in Example 1, the high-entropy ceramic / polymer composite dielectric film prepared in this example is defined as KBFNT3 / PVDF film.

[0046] In Example 4, the XRD characterization pattern of the KBFNT3 sample is shown below. Figure 1 See SEM characterization image. Figure 2 For particle size statistics (d), please refer to [link / reference]. Figure 3 (d). XRD characterization of the KBFNT3 / PVDF membrane can be found in [reference]. Figure 4 See SEM characterization image. Figure 5 (e) Dielectric performance test results are shown in [reference]. Figure 6 See energy storage performance results. Figure 7 .

[0047] Example 5 The difference between this embodiment and Embodiment 1 is as follows: In step S1, the original powder materials bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K... 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x O3 was used as the raw material, where x = 1 / 3; KBFNT powder was prepared using a hydrothermal method. That is, the molar ratio of iron ions, niobium ions, and titanium ions in the KBFNT powder was 1 / 3:1 / 3:1 / 3. The KBFNT powder prepared in this example is defined as sample KBFNT4.

[0048] In step S2, a PDA shell is formed on the outside of the KBFNT particles in the KBFNT4 sample. Other specific processes are the same as step S2 in Example 1.

[0049] In step S3, 0.025g of KBFNT4 sample is taken, and the other specific procedures are the same as step S3 in Example 1.

[0050] In step S4, the same as step S4 in Example 1, the high-entropy ceramic / polymer composite dielectric film prepared in this example is defined as KBFNT4 / PVDF film.

[0051] In Example 5, the XRD characterization pattern of the KBFNT4 sample is shown below. Figure 1 See SEM characterization image. Figure 2 For particle size statistics (e), please refer to [reference needed]. Figure 3 (e). XRD characterization of the KBFNT4 / PVDF membrane is shown in Figure (e). Figure 4 See SEM characterization image. Figure 4 (f) See the dielectric performance test results. Figure 6 See energy storage performance results. Figure 7 .

[0052] Example 6 S1. Preparation of high-entropy ceramic KBFNT powder: Same as step S1 in Example 5.

[0053] S2. An Al2O3 shell and a PDA shell are sequentially formed on the outer side of the KBFNT particles to obtain KBFNT@Al2O3@PDA powder. Specifically, this includes: S21. Weigh KBFNT powder, add 30 ml of water and 30 ml of ethanol, sonicate for 0.5 h, stir for 0.5 h to form a suspension, and record it as KBFNT suspension; weigh Al(NO3)3·9(H2O), add 30 ml of water, stir to dissolve, and record it as aluminum nitrate solution.

[0054] S22. Add aluminum nitrate solution to KBFNT suspension, stir for 1 h, add ammonia water dropwise to adjust pH to 9.0~10.0, stir for 12 h, centrifuge, wash and dry, then calcine in a muffle furnace at 600℃ for 2 h to obtain KBFNT@Al2O3 powder, wherein the mass ratio of KBFNT:Al2O3 is 1:0.02, denoted as K@2Al sample.

[0055] S23. Obtain a Tris-HCl buffer solution with a concentration of 0.1 mol / L and a pH of 8.0–9.0. Add the KBFNT@Al2O3 powder to the Tris-HCl buffer solution and ultrasonically disperse it for 1 hour at a power of 200 W to obtain a KBFNT@Al2O3 suspension.

[0056] S24. Add dopamine hydrochloride to the KBFNT@Al2O3 suspension, ultrasonically disperse at 200W for 1 hour, stir and react at 30℃ for 24 hours, centrifuge, wash and dry at 70℃ for 12 hours to obtain KBFNT@Al2O3@PDA powder.

[0057] S3. Mix the KBFNT@Al2O3@PDA powder and the organic polymer PVDF at a mass ratio of 5%:1 to obtain the high-entropy ceramic / polymer composite dielectric slurry KBFNT@Al2O3@PDA / PVDF. The specific process is the same as step S3 in Example 1.

[0058] S4. Using the high-entropy ceramic / polymer composite dielectric slurry obtained in step S3, a single-layer high-entropy ceramic / polymer composite dielectric film is prepared and denoted as K@2Al / PVDF film. The specific process is the same as step S4 in Example 1.

[0059] In Example 6, the XRD characterization pattern of the K@2Al sample is shown below. Figure 8 See SEM characterization image. Figure 9 (a) See particle size distribution chart. Figure 10 (a). XRD characterization of the K@2Al / PVDF film is shown in Figure (a). Figure 13 See SEM characterization image. Figure 14 (a) Dielectric property results are shown in [reference]. Figure 15 See energy storage performance results. Figure 16 .

[0060] Example 7 The difference between this embodiment and Embodiment 6 is that in step S2, the mass ratio of KBFNT to Al2O3 is 1:0.04, denoted as K@4Al sample. The other steps are the same as in Embodiment 6.

[0061] The monolayer high-entropy ceramic / polymer composite dielectric film prepared in Example 7 is denoted as K@4Al / PVDF film.

[0062] In Example 7, the XRD characterization pattern of the K@4Al sample is shown below. Figure 8 See SEM characterization image. Figure 9 (b) See particle size distribution chart. Figure 10 (b) See the TEM characterization image of the K@4Al sample. Figure 11 See HAADF characterization diagram. Figure 12 XRD characterization of the K@4Al / PVDF film can be found in [reference needed]. Figure 13 See SEM characterization image. Figure 14 (b) Dielectric property results are shown in [reference]. Figure 15 See energy storage performance results. Figure 16 .

[0063] Example 8 The difference between this embodiment and Embodiment 6 is that in step S2, the mass ratio of KBFNT to Al2O3 is 1:0.06, denoted as K@6Al sample. The other steps are the same as in Embodiment 6.

[0064] The monolayer high-entropy ceramic / polymer composite dielectric film prepared in Example 8 is denoted as K@6Al / PVDF film.

[0065] In Example 8, the XRD characterization pattern of the K@6Al sample is shown below. Figure 8 See SEM characterization image. Figure 9 (c) See particle size distribution chart. Figure 10 (c) XRD characterization of the K@6Al / PVDF film is shown in [reference]. Figure 13 See SEM characterization image. Figure 14 (c) Dielectric property results are shown in [reference]. Figure 15 See energy storage performance results. Figure 16 .

[0066] Example 9 The difference between this embodiment and Embodiment 6 is that in step S2, the mass ratio of KBFNT to Al2O3 is 1:0.08, denoted as K@8Al sample. The other steps are the same as in Embodiment 6.

[0067] The monolayer high-entropy ceramic / polymer composite dielectric film prepared in Example 9 is denoted as K@8Al / PVDF film.

[0068] In Example 9, the XRD characterization pattern of the K@8Al sample is shown below. Figure 8 See SEM characterization image. Figure 9 For the particle size distribution chart (d), please refer to [link / reference]. Figure 10 (d). XRD characterization of the K@8Al / PVDF film can be found in [reference]. Figure 13 See SEM characterization image. Figure 14 (d) Dielectric property results are shown in [reference]. Figure 15 See energy storage performance results. Figure 16 .

[0069] Example 10 Steps S1 and S2 are the same as in Example 7.

[0070] S3. Mix the KBFNT@Al2O3@PDA powder and the organic polymer PEI at a mass ratio of 7.5%:1 to obtain a high-entropy ceramic / polymer composite dielectric slurry of 7.5%KBFNT@Al2O3@PDA / PEI.

[0071] The KBFNT@Al2O3@PDA powder and the organic polymer PEI were mixed at a mass ratio of 2.5%:1 to obtain a high-entropy ceramic / polymer composite dielectric slurry of 2.5%KBFNT@Al2O3@PDA / PEI. The specific process is the same as step S3 in Example 1.

[0072] S4. Prepare a high-entropy ceramic / polymer composite dielectric film with three dielectric layers, specifically including: sequentially coating a bottom layer, an intermediate layer, and a top layer; wherein, the bottom layer is a PEI film; the intermediate layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 7.5%:100%; the top layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 2.5%:100%.

[0073] The multilayer composite film was sequentially subjected to vacuum drying, quenching, and peeling to obtain a multilayer composite dielectric film based on KBFNT@Al2O3@PDA. Specifically, the prepared multilayer composite dielectric film was dried in a vacuum oven at 70℃ for 12 hours. After quenching at 200℃ for 4 hours, ice water was immediately poured on it to completely peel the film off the glass slide, resulting in a multilayer composite dielectric film, defined as multilayer composite dielectric film 1 (i.e., 0-7.5-2.5 in the figure).

[0074] The microstructure and dielectric properties of the multilayer composite dielectric film 1 were investigated. The XRD characterization pattern of the multilayer composite dielectric film 1 is shown in [reference needed]. Figure 17 (a) See SEM characterization image in section (a). Figure 17 (b) Dielectric property results are shown in [reference]. Figure 18 (a) See energy storage performance results in section (a). Figure 19 and Figure 20 .

[0075] Example 11 The difference between this embodiment and Embodiment 10 is that, in step S4, in the preparation of the high-entropy ceramic / polymer composite dielectric film with three dielectric layers, the bottom layer is a PEI film; the middle layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 2.5%:100%; and the top layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 7.5%:100%.

[0076] The remaining steps are the same as in Example 10. The multilayer composite dielectric film obtained is defined as multilayer composite dielectric film 2 (i.e., 0-2.5-7.5 in the figure).

[0077] The microstructure and dielectric properties of the multilayer composite dielectric film 2 were investigated. The XRD characterization diagram of the multilayer composite dielectric film 2 is shown in Figure 17(a), and the dielectric property results are shown in [reference needed]. Figure 18 (a)

[0078] Example 12 The difference between this embodiment and Embodiment 10 is that in step S4, in the preparation of the high-entropy ceramic / polymer composite dielectric film with three dielectric layers, the bottom layer is a PEI film; the middle layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 2.5%:100%; and the top layer is a PEI film.

[0079] The remaining steps are the same as in Example 10. The multilayer composite dielectric film obtained is defined as multilayer composite dielectric film 3 (i.e., 0-2.5-0 in the figure).

[0080] The XRD characterization pattern of the multilayer composite dielectric thin film 3 is shown in the figure. Figure 17 (a)

[0081] Example 13 The difference between this embodiment and Embodiment 10 is that, in step S4, in the preparation of the high-entropy ceramic / polymer composite dielectric film with three dielectric layers, the bottom layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 2.5%:100%; the middle layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 7.5%:100%; and the top layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 2.5%:100%.

[0082] The remaining steps are the same as in Example 10. The multilayer composite dielectric film obtained is defined as multilayer composite dielectric film 4 (i.e., 2.5-7.5-2.5 in the figure).

[0083] The microstructure and dielectric properties of the multilayer composite dielectric film 4 were examined. The XRD characterization pattern of the multilayer composite dielectric film 4 is shown in [reference needed]. Figure 17 (a) Dielectric property results are shown in [reference]. Figure 18 (a) See energy storage performance in section (a). Figure 19 .

[0084] Example 14 The difference between this embodiment and Embodiment 10 is that in step S4, in the preparation of the high-entropy ceramic / polymer composite dielectric film with three dielectric layers, the bottom layer is a PEI film; the middle layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 5%:100%; and the top layer is a PEI film.

[0085] The remaining steps are the same as in Example 10. The multilayer composite dielectric film obtained is defined as multilayer composite dielectric film 5 (i.e., 0-5-0 in the figure).

[0086] For the dielectric properties of the multilayer composite dielectric film 5, please refer to [reference needed]. Figure 18 (b)

[0087] Example 15 The difference between this embodiment and Embodiment 10 is that, in step S4, in the preparation of the high-entropy ceramic / polymer composite dielectric film with three dielectric layers, the bottom layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 5%:100%; the middle layer is a PEI film; and the top layer is a high-entropy ceramic / polymer composite dielectric film, wherein the mass ratio of KBFNT@Al2O3@PDA powder to PEI is 5%:100%.

[0088] The remaining steps are the same as in Example 10. The multilayer composite dielectric film obtained is defined as multilayer composite dielectric film 6 (i.e., 5-0-5 in the figure).

[0089] For the dielectric properties of the multilayer composite dielectric film 6, please refer to [reference needed]. Figure 18 (b)

[0090] In Examples 1-15 above, the parameters for preparing KBFNT in step S1 can be arbitrarily selected within the following ranges: stirring time is 1-7 h; hydrothermal reaction temperature is 180-220 ℃ and reaction time is 20-28 h; drying temperature is 50-90 ℃ and drying time is 10-24 h; calcination temperature is 500-900 ℃ and calcination time is 1-3 h. The preparation parameters in step S4 can also be arbitrarily selected within the following ranges: a high-entropy ceramic / polymer composite dielectric slurry is uniformly coated onto clean glass and dried at 50-80 ℃ for 10-14 h; finally, the obtained PVDF-containing composite dielectric film is heated at 180-220 ℃ for 5-20 min and immediately placed in ice water for quenching; the obtained PEI-containing composite dielectric film is heated at 180-220 ℃ for 3-6 h and then naturally cooled to room temperature before being placed in water and removed.

[0091] Comparative Example 1 In this comparative example, PVDF dielectric energy storage films are prepared using PVDF as raw material via a casting method, specifically including the following steps: 0.5 g of PVDF was dispersed in 10.0 mL of DMF and stirred until homogeneous to obtain a PVDF DMF solution, which was used to prepare nano-dielectric thin films.

[0092] A 70 μL DMF solution of PVDF was uniformly coated onto a clean glass substrate and dried at 60 °C for 12 h to remove the solvent. Finally, the film was heated at 200 °C for 10 min and then immediately quenched in ice water to obtain a single-layer PVDF dielectric energy storage film, which was designated as Comparative Example 1 (the PVDF corresponding to the figure).

[0093] The XRD characterization diagram of the sample in Comparative Example 1 can be found in [reference needed]. Figure 4 ( Figure 4 (See the PVDF schematic diagram in the image), and the SEM characterization diagram. Figure 5 (a) Dielectric property results are shown in [reference]. Figure 6 See energy storage performance results. Figure 7 .

[0094] Comparative Example 2 In this comparative example, PEI dielectric energy storage films are prepared using PEI as raw material via a casting method, specifically including the following steps: 0.5 g of PEI was dispersed in 10.0 mL of NMP and stirred until homogeneous to obtain an NMP solution of PEI, which was used to prepare nano-dielectric thin films.

[0095] A 70 μL NMP solution of PEI was uniformly coated onto a clean glass substrate and dried at 60 °C for 12 h to remove the solvent. Finally, the film was heated at 200 °C for 4 h and immediately quenched in ice water to obtain a single-layer PEI dielectric energy storage film, which was designated as Comparative Example 2. Figure 18 In (a), the blue curve corresponds to a single layer of KBFNT (a non-high-entropy ceramic).

[0096] For the dielectric properties of the sample in Comparative Example 2, please refer to [reference needed]. Figure 18 (a) in the middle.

[0097] Comparative Example 3 Compared with Comparative Example 2, a three-layer PEI dielectric energy storage film was formed, and this sample is designated as Comparative Example 3 (corresponding to 0-0-0 in the figure). That is, the thickness of the PEI dielectric energy storage film in Comparative Example 3 is three times the thickness of the PEI dielectric energy storage film prepared in Comparative Example 2. Other processes are the same as those in Comparative Example 2.

[0098] The XRD characterization diagram of the sample in Comparative Example 3 is shown in Figure 17(a), and the dielectric properties are shown in Figure 17(a). Figure 18See (a) for energy storage performance results. Figure 19 (a).

[0099] Results analysis: (1) The KBFNT0, KBFNT1, KBFNT2, KBFNT3 and KBFNT4 samples prepared in Examples 1-5 were characterized by bulk XRD analysis.

[0100] The experimental procedure was as follows: X-ray diffraction (XRD) was used to detect the phase composition of each KBFNT powder. The test conditions were: Cu-K α The target was used as the radiation source. The test tube voltage was 40 kV, the test tube current was 40 mA, the scan step size was 0.02°, and the scan rate was 0.05° / s. Analysis was performed using Jade software, and the results are as follows: Figure 1 As shown.

[0101] pass Figure 1 It can be seen that the diffraction peaks of samples KBFNT0, KBFNT1, KBFNT2, KBFNT3, and KBFNT4 are basically consistent, indicating that they all form single-phase perovskite solid solutions without impurities. Figure 1 The right-hand figure shows a magnified view of the diffraction peaks corresponding to the (111) and (200) crystal planes. None of the diffraction peaks show splitting. This is consistent with the tolerance factor of the KBFNT system. t The tolerance factor is approximately 1.007, close to that of an ideal cubic perovskite. t =1), indicating that all KBFNT ceramic powders are pseudo-cubic phases. Meanwhile, Figure 1 The characterization results also show that as the amount of Fe and Nb added increases, the diffraction peaks of the (111) and (200) crystal planes of the sample gradually shift to lower angles, indicating that the lattice parameters of the ceramic powder are increasing. This is because the Fe at the B site... 3+ and Nb 5+ The ionic radii of 0.645 Å and 0.64 Å (coordination number 6) are greater than those of partially substituted Ti. 4+ The ionic radius of 0.605 Å increases the lattice parameter.

[0102] (2) Take a small amount of each of the KBFNT0, KBFNT1, KBFNT2, KBFNT3, and KBFNT4 samples prepared in Examples 1-5 and spread them evenly on the conductive adhesive. Scan them using a scanning electron microscope (SEM). The results are as follows: Figure 2 As shown, for Figure 2 Particle size analysis was performed to obtain Figure 3 .

[0103] in, Figure 2In the image, (a) corresponds to the SEM characterization of sample KBFNT0, (b) corresponds to the SEM characterization of sample KBFNT1, (c) corresponds to the SEM characterization of sample KBFNT2, (d) corresponds to the SEM characterization of sample KBFNT3, and (e) corresponds to the SEM characterization of sample KBFNT4. Figure 3 In the figure, (a) corresponds to the particle size distribution of KBFNT0 sample, (b) corresponds to the particle size distribution of KBFNT1 sample, (c) corresponds to the particle size distribution of KBFNT2 sample, (d) corresponds to the particle size distribution of KBFNT3 sample, (e) corresponds to the particle size distribution of KBFNT4 sample, and (f) is a statistical chart of the particle size of the five KBFNT samples.

[0104] See Figure 2 High-entropy ceramic KBFNT consists entirely of irregular cubes. Figure 3 This demonstrates that the average particle size of the powder is 80~200 nm, and the powder particles are fine and uniform.

[0105] (3) The KBFNT0 / PVDF film, KBFNT1 / PVDF film, KBFNT2 / PVDF film, KBFNT3 / PVDF film, KBFNT4 / PVDF film prepared in Examples 1-5, and the PVDF dielectric energy storage film prepared in Comparative Example 1 were analyzed and detected by XRD. The comparison results are shown in [reference]. Figure 4 .

[0106] pass Figure 4 It can be seen that the KBFNT@PDA / PVDF high-entropy ceramic / polymer composite dielectric films prepared in Examples 1-5 all contain strong perovskite phase diffraction peaks, except for the diffraction peaks of the PVDF-specific phase structure.

[0107] In the XRD pattern of the PVDF dielectric energy storage film obtained in Comparative Example 1, the diffraction peaks near 17.3° and 22.5° correspond to the (020) crystal plane of the α phase and the (110) crystal plane of the β phase of PVDF, respectively, with the β phase PVDF as the main phase. In the XRD patterns of KBFNT0 / PVDF film to KBFNT4 / PVDF film, the diffraction peaks of PVDF and KBFNT coexist, indicating that the KBFNT filler did not chemically react with PVDF.

[0108] (4) The KBFNT0 / PVDF film, KBFNT1 / PVDF film, KBFNT2 / PVDF film, KBFNT3 / PVDF film and KBFNT4 / PVDF film prepared in Examples 1 to 5 of the present invention and the PVDF dielectric energy storage film prepared in Comparative Example 1 were observed by SEM. The results are as follows: Figure 5 As shown.

[0109] Figure 5In the image, (a) is the SEM characterization image of the PVDF dielectric energy storage film, (b) is the SEM characterization image of the KBFNT0 / PVDF film, (c) is the SEM characterization image of the KBFNT1 / PVDF film, (d) is the SEM characterization image of the KBFNT2 / PVDF film, (e) is the SEM characterization image of the KBFNT3 / PVDF film, and (f) is the SEM characterization image of the KBFNT4 / PVDF film.

[0110] See Figure 5 SEM images show that the composite dielectric film has no obvious pores and possesses a smooth and dense surface microstructure. The filler in the composite dielectric film is relatively uniformly dispersed, proving that KBFNT@PDA powder and PVDF have good compatibility.

[0111] (5) The KBFNT0 / PVDF film, KBFNT1 / PVDF film, KBFNT2 / PVDF film, KBFNT3 / PVDF film, and KBFNT4 / PVDF film prepared in Examples 1-5 of the present invention, and the PVDF dielectric energy storage film prepared in Comparative Example 1, were each fabricated with gold electrodes of 2 mm diameter on both sides using an ion sputtering apparatus. The dielectric properties and energy storage properties were tested using conventional testing methods, and the results are as follows: Figures 6-7 As shown.

[0112] pass Figure 6 It can be seen that, compared with PVDF dielectric energy storage films, the high-entropy ceramic / polymer composite dielectric film KBFNT / PVDF prepared in this invention has higher dielectric properties and energy storage density. This indicates that the strategy of introducing high-entropy ceramic fillers into the polymer matrix to improve dielectric properties is effective. The dielectric constant of the sample increases with the increase of the amount of ceramic fillers Fe and Nb. At 1 kHz, the PVDF dielectric energy storage film ( Figure 6 (b) PVDF), KBFNT0 / PVDF membrane ( Figure 6 (b) Samples 0), KBFNT1 / PVDF membrane ( Figure 6 (b) Samples 1), KBFNT2 / PVDF membrane ( Figure 6 (b) Samples 2), KBFNT3 / PVDF membrane ( Figure 6 (b) Samples 3) and KBFNT4 / PVDF membrane ( Figure 6 The dielectric constants of Samples 4 in (b) are 8.8, 11.4, 13.2, 13.3, 14.1 and 14.8, respectively. This is because as the amount of Fe and Nb added increases, the entropy of the ceramic filler increases, the degree of structural disorder increases, the dipole polarization is enhanced, and thus the dielectric constant of the composite dielectric film increases.

[0113] pass Figure 7 (a) It can be seen that under an electric field of 150 MV / m, the PVDF dielectric energy storage film, KBFNT0 / PVDF film, KBFNT1 / PVDF film, KBFNT2 / PVDF film, KBFNT3 / PVDF film, and KBFNT4 / PVDF film exhibit [the following characteristics]. P - E The curve is obtained through calculation. Figure 7 (b) and Figure 7 (c) The indicated result, Figure 7 (b) The effective energy storage density of the above composite membrane can be seen. W rec They are 1.23 J / cm 3 3.36 J / cm 3 4.76 J / cm 3 4.74 J / cm 3 4.67 J / cm 3 and 5 J / cm 3 Energy storage efficiency η The percentages were 75.1%, 71.1%, 69%, 64.5%, 62.3%, and 61.1%, respectively. The addition of filler significantly improved the energy storage density of the composite dielectric film, but the energy storage efficiency decreased due to the increase in ferroelectric losses. Figure 7 (c) It can be seen that as x increases, the filler entropy is higher, and the polarization intensity P shows an increasing trend. The optimal KBFNT4 / PVDF can reach 15.08 μC / cm. 2 .

[0114] (6) XRD phase analysis was performed on the K@2Al, K@4Al, K@6Al, K@8Al samples and K (in Example 5, no Al2O3 shell was formed, and it was used as a control) prepared in Examples 6-9 of this invention. The results are as follows: Figure 8 As shown.

[0115] Depend on Figure 8 It can be seen that the K, K@2Al, K@4Al, K@6Al, and K@8Al samples in Examples 5-9 have strong perovskite phase diffraction peaks, no obvious impurity phases, and the diffraction peak shifts are basically consistent, indicating that the Al2O3 shell does not affect the crystal structure.

[0116] (7) The K@2Al, K@4Al, K@6Al and K@8Al samples prepared in Examples 6-9 of this invention were observed by SEM, and the characterization results are as follows: Figure 9 As shown, the particle size statistics are as follows: Figure 10As shown. Energy-dispersive X-ray spectroscopy (EDS) was used to perform elemental scanning of the K@4Al sample. The results are as follows. Figure 11 As shown. Further transmission electron microscopy (TEM) analysis was performed on the K@4Al sample, yielding... Figure 12 . Figure 9 In the image, (a) corresponds to the SEM characterization of the K@2Al sample, (b) corresponds to the SEM characterization of the K@4Al sample, (c) corresponds to the SEM characterization of the K@6Al sample, and (d) corresponds to the SEM characterization of the K@8Al sample. Figure 10 In the diagram, (a) corresponds to the particle size distribution of the K@2Al sample, (b) corresponds to the particle size distribution of the K@4Al sample, (c) corresponds to the particle size distribution of the K@6Al sample, and (d) corresponds to the particle size distribution of the K@8Al sample.

[0117] Depend on Figure 9 It can be seen that the high-entropy ceramic samples K@2Al, K@4Al, K@6Al, and K@8Al in Examples 6-9 all exhibit irregular cubic shapes. Figure 10 It can be seen that after coating, the average particle size of the powder is 250~400 nm, which is an increase compared to the particle size of the uncoated Al2O3 powder. Figure 11 It can be seen that Al2O3 and KBFNT powder are in full contact and relatively evenly distributed. Figure 12 A continuous light-colored thin layer with a thickness of about 3 nm was observed to coat the surface of the powder, proving the existence of the Al2O3 shell.

[0118] (8) Take the K@2Al / PVDF film, K@4Al / PVDF film, K@6Al / PVDF film, K@8Al / PVDF film from Examples 6-9 and the PVDF dielectric energy storage film prepared in Comparative Example 1, and perform XRD analysis on them respectively. The results are as follows: Figure 13 As shown.

[0119] pass Figure 13 It can be seen that in Examples 6-9, the diffraction peaks of PVDF and KBFNT@Al2O3 can be clearly seen in the K@2Al / PVDF film, K@4Al / PVDF film, K@6Al / PVDF film, K@8Al / PVDF film and PVDF dielectric energy storage film, with no other impurity peaks, indicating that no other impurities were generated during the preparation process.

[0120] (9) The K@2Al / PVDF film, K@4Al / PVDF film, K@6Al / PVDF film, K@8Al / PVDF film and PVDF dielectric energy storage film from Examples 6 to 9 were observed by SEM. The results are as follows: Figure 14 As shown. Figure 14In the image, (a) corresponds to the SEM characterization of the K@2Al / PVDF film, (b) corresponds to the SEM characterization of the K@4Al / PVDF film, (c) corresponds to the SEM characterization of the K@6Al / PVDF film, and (d) corresponds to the SEM characterization of the K@8Al / PVDF film.

[0121] See Figure 14 Each sample has a smooth and dense surface without obvious pores, and the filler is evenly distributed.

[0122] (10) Take the K@2Al / PVDF film, K@4Al / PVDF film, K@6Al / PVDF film, and K@8Al / PVDF film from Examples 6-9, and prepare gold electrodes with a diameter of 2 mm on both sides of them using an ion sputtering instrument. Test their dielectric properties and energy storage properties according to conventional testing methods. The specific results are as follows: Figures 15-16 As shown.

[0123] Depend on Figure 15 It can be seen that at 1 kHz, the dielectric constants of the K@2Al / PVDF, K@4Al / PVDF, K@6Al / PVDF, and K@8Al / PVDF composite dielectric films are 16, 15.4, 14.7, and 14.1, respectively. The composite dielectric films coated with 2 wt.% and 4 wt.% Al2O3 obtained higher dielectric constants. This is because the Al2O3 coating in these two samples is relatively small, and the Al2O3 shell is thinner compared to the KBFNT ceramic particles, so its effect on the dielectric constant is not as significant as that of interfacial polarization.

[0124] Depend on Figure 16 (a) is the breakdown field strength of KBFNT@x wt.%Al2O3 / PVDF composite membrane. P - E As shown in the figure, for K@2Al / PVDF, K@4Al / PVDF, K@6Al / PVDF, and K@8Al / PVDF composite dielectric films, the breakdown field strength gradually increases with the increase of the Al2O3 shell mass fraction. This is attributed to the high-insulation Al2O3 shell coating. The Al2O3 shell acts as a charge shielding layer, restricting charge movement and reducing leakage current. The energy storage efficiency of the composite film also increases with the increase of the Al2O3 shell mass fraction, which is consistent with the decrease in dielectric loss of the composite film. Meanwhile, the composite film... P max , P r and Δ P Both decrease with increasing x, because the dielectric constant of Al2O3 is lower than that of KBFNT powder, and excessive coating will lead to a decrease in the overall dielectric constant of the filler. Comparing the effective energy storage performance of each composite membrane under breakdown field strength, the effective energy storage density of each composite membrane (… Wrec The values ​​are 15.13 J / cm². 3 16.39 J / cm 3 14.66 J / cm 3 14.41 J / cm 3 The energy storage efficiencies (η) were 65.6%, 71.8%, 72.3%, and 72.7%, respectively, with K@4Al / PVDF having the highest effective energy storage density.

[0125] pass Figure 15 and Figure 16 It can be seen that Al2O3 coating of KBFNT effectively reduces the leakage current and dielectric loss of the composite dielectric film, thereby improving energy storage efficiency. However, excessively thick Al2O3 coating can lead to a significant decrease in polarization intensity, resulting in a decrease in energy storage density. The KBFNT@4%Al2O3@PDA / PVDF composite dielectric film exhibits the best energy storage performance, with a dielectric constant of 15.4 at 1 kHz and an effective energy storage density of 14.41 J / cm³. 3 .

[0126] (11) XRD was performed on the multilayer composite dielectric film 1 (0-7.5-2.5) from Example 10, the multilayer composite dielectric film 3 (0-2.5-0) from Example 12, and the multilayer composite dielectric film 4 (2.5-7.5-2.5) from Example 13, and XRD was performed on the sample of Comparative Example 3 (0-0-0) from Comparative Example 3. The results are as follows. Figure 17 As shown in (a). Simultaneously, SEM was performed on the cross-section of the multilayer composite dielectric film 1 (0-7.5-2.5), and the characterization image is shown below. Figure 17 As shown in (b).

[0127] See Figure 17 (a) A diffuse scattering peak corresponding to the amorphous PEI structure was observed near 17°. Furthermore, apart from the diffraction peak of KBFNT@Al2O3@PDA, no other characteristic diffraction peaks were observed, indicating that no impurity phase was introduced into the composite film. See also Figure 17 (b) The filler is uniformly distributed in the sample cross section, and the composite dielectric film has no obvious pores, indicating that the film is dense.

[0128] (12) The multilayer composite dielectric films 1-6 prepared in Examples 10-15, the single-layer PEI dielectric energy storage film prepared in Comparative Example 2, and the multilayer PEI dielectric energy storage film prepared in Comparative Example 3 were used to prepare gold electrodes with a diameter of 2 mm on both sides using an ion sputtering instrument. Their dielectric properties and energy storage properties were tested according to conventional testing methods. The specific results are as follows: Figures 18-20 As shown.

[0129] Depend on Figure 18 As shown in (a), within the frequency range of 100Hz to 1MHz, the dielectric constant of the multilayer composite dielectric film 1 maintains good dielectric stability, and the dielectric loss is less than 0.01. Furthermore, the performance of the multilayer composite dielectric film is superior to that of the multilayer PEI dielectric energy storage film prepared in Comparative Example 3 and the single-layer PEI dielectric energy storage film prepared in Comparative Example 2. At 1kHz, multilayer composite dielectric films 1, 2, and 4 all exhibit relatively high dielectric constants. ε r The values ​​are 6.23, 5.04, and 5.98 respectively, while the loss tangent tan δ All were as low as 0.007.

[0130] from Figure 18 As can be seen in (b), the dielectric constants of multilayer composite dielectric films 1, 5, and 6 are dependent on temperature. These results indicate that the prepared composite films not only possess high dielectric constants but also exhibit temperature dependence. ε r and low tan δ It also possesses excellent temperature stability. At 150℃, the dielectric constants of multilayer composite dielectric films 1, 5, and 6 are... ε r The values ​​are 4.01, 6.48, and 4.85 respectively, while the loss tangent is tan δ Although the dielectric loss increases with temperature, it remains below 0.04, demonstrating excellent temperature stability. This result further confirms the positive contribution of high-entropy ceramic fillers to the composite material's performance.

[0131] Figure 18 (c) also shows the temperature coefficient of capacitance (TCC) of the multilayer composite dielectric film 1 at 1 kHz, with a value at 25 °C. ε r Using this as a benchmark, as shown in the figure, the corresponding temperature ranges for TCC changes of 5% and 10% are -20 to 45℃ and -20 to 176℃, respectively. This indicates that the corresponding film capacitors can operate stably over a wide temperature range.

[0132] This experiment used pure polymer PEI (comparative example 2 sample) as a comparison to determine the energy storage density at room temperature of multilayer composite dielectric film 1, multilayer composite dielectric film 2, and multilayer composite dielectric film 4. W rec Energy storage density of multilayer composite dielectric thin film 1 under different electric fields at 150℃ W rec .

[0133] pass Figure 19 It can be seen that, under normal temperature conditions, the Δ of the multilayer composite dielectric film 1 P 4.0 μC / cm 2 , W rec It is 8.71 J / cm 3 And at room temperature η The energy storage performance of the multilayer composite dielectric film 2 is 96%; the energy storage performance of the multilayer composite dielectric film 2 is slightly lower than that of the multilayer composite dielectric film 1, with energy storage densities of Δ... P 1.7 μC / cm 2 , W rec 3.8 J / cm 3 , η The Δ value of the multilayer composite dielectric thin film 4 is 62%. P 1.8 μC / cm 2 , W rec 2.1 J / cm 3 , η It is 65%.

[0134] pass Figure 20 As can be seen from (a) and (b), the energy storage performance of the multilayer composite dielectric film 1 changes under different electric field conditions at a high temperature of 150℃. It can be seen that it can still maintain high energy storage performance even under conditions close to the breakdown field strength of 440MV / m. W rec It is 11.4 J / cm 3 , η It is 86%, and the polarization intensity Δ P Reaching 5.6 μC / cm 2 .

[0135] like Figure 20 As shown in (c), because the filler is a high-entropy ceramic powder, the polarization reversal time is greatly shortened. Therefore, the prepared multilayer composite dielectric film has an extremely fast charge and discharge speed under a load of 300Ω and 200MVm. t 0.9 The energy storage density is 2.38 ns. W dis Reaching 4.24 J / cm 3 .

[0136] The preparation process provided by this invention is simple, and the composition and ratio of materials are easy to optimize and adjust. By increasing the entropy of the ceramic filler, the dielectric properties and energy storage capacity of the prepared high-entropy ceramic / polymer composite dielectric film are improved, meeting the dielectric energy storage performance requirements of high-dielectric energy storage capacitors. Furthermore, based on this, multilayer composite dielectric films 1, 2, 4, 5, and 6 were prepared, effectively improving the breakdown field strength, expanding the application range of composite dielectric films, and providing an effective solution for the field of pulse electronics with their rapid charge and discharge rates.

[0137] 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 method for preparing a high-entropy ceramic / polymer composite dielectric thin film, characterized in that, Includes the following steps: S1. The original powdered bismuth nitrate, ferric nitrate, titanium dioxide, niobium oxide, and potassium hydroxide are mixed according to the general structural formula (K). 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x KBFNT powder was prepared by adding O3 as an ingredient and using a hydrothermal method, wherein 0≤x≤1 / 3; S2. A PDA shell is formed on the outside of the KBFNT particles of the KBFNT powder to obtain KBFNT@PDA powder; S3. Mix the KBFNT@PDA powder and organic polymer at a mass ratio of (2.5%~10%):1 to obtain a high-entropy ceramic / polymer composite dielectric slurry; S4. Prepare a high-entropy ceramic / polymer composite dielectric film; the high-entropy ceramic / polymer composite dielectric film includes at least one dielectric film; At least one layer of the dielectric film is prepared using the high-entropy ceramic / polymer composite dielectric slurry.

2. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 1, characterized in that, Step S2 also includes forming an Al2O3 shell before forming the PDA shell, and then forming the PDA shell on the outside of the Al2O3 shell. The formation of the Al2O3 shell includes: The KBFNT powder was dispersed in an ethanol-water solution, sonicated for 20-40 min, and then stirred for 20-40 min to obtain a KBFNT suspension. The KBFNT suspension was mixed with aluminum nitrate solution and stirred for 30–90 min. The pH value was adjusted to 9.0–10.0 with ammonia water, and then stirred for 10–15 h. After centrifugation, washing and drying, the mixture was calcined at 500–800 °C for 1–3 h to obtain KBFNT@Al2O3 powder. The mass ratio of the KBFNT powder to aluminum nitrate was 1:(0.15–0.60).

3. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 2, characterized in that, The formation of the PDA shell includes: A Tris-HCl buffer solution was prepared, wherein the concentration of the Tris-HCl buffer solution was 0.05–0.2 mol / L and the pH value was 8.0–9.0; The KBFNT@Al2O3 powder was added to the Tris-HCl buffer solution and ultrasonically dispersed at a power of 100-500W for 0.5-2h to obtain a KBFNT@Al2O3 suspension. Dopamine hydrochloride was added to the KBFNT@Al2O3 suspension, and the mixture was ultrasonically dispersed at 100-500W for 0.5-1h. The mixture was then stirred at 20-40℃ for 10-24h, centrifuged, washed, and dried at 50-80℃ for 6-12h to obtain KBFNT@Al2O3@PDA powder.

4. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 1, characterized in that, Step S3 includes: S31. Dissolve the organic polymer in an organic solvent and stir until homogeneous to obtain an organic polymer solution; S32. The KBFNT@PDA powder is ultrasonically dispersed in the organic polymer solution, and after stirring, a high-entropy ceramic / polymer composite dielectric slurry is obtained.

5. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 4, characterized in that, The organic polymer is PVDF, and the organic solvent is DMF, satisfying the mass ratio of PVDF to DMF of 0.5 g: 10.0 mL; Alternatively, the organic polymer is PEI, and the organic solvent is NMP, satisfying a mass ratio of PEI to NMP of 0.5 g: 10.0 mL.

6. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 1, characterized in that, In step S1, the structural formula (K) 0.5 Bi 0.5 (Fe) x Nb x Ti 1-2x In O3, x = 0.1, 0.2, 0.3 or 1 / 3.

7. The method for preparing a high-entropy ceramic / polymer composite dielectric thin film according to claim 1, characterized in that, In step S3, the organic polymer is at least one of polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymer, poly(vinylidene fluoride-trifluoroethylene) copolymer, polyimide, and polyetherimide.

8. The high-entropy ceramic / polymer composite dielectric thin film according to claim 1, characterized in that, In step S4, the dielectric film consists of three layers, namely a bottom layer, a middle layer, and a top layer stacked sequentially. At least one of the bottom layer, the middle layer, and the top layer is prepared using the high-entropy ceramic / polymer composite dielectric slurry. The thickness of the bottom layer, the middle layer, and the top layer are all in the range of 5~6 μm.

9. A high-entropy ceramic / polymer composite dielectric thin film, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the high-entropy ceramic / polymer composite dielectric thin film according to claim 8 or 9 in the preparation of high-dielectric energy storage capacitors.

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