Entropy-regulated composite dielectric thin film and preparation method thereof

Abstract

The present application provides an entropy-regulated composite dielectric film, which comprises a polymer matrix; and fillers dispersed in the polymer matrix, wherein the fillers comprise Bi 4‑a M 1a Ti (3‑3b) M 2b O 12 , wherein M1 comprises at least one of lanthanum, neodymium, samarium and praseodymium, M2 comprises at least one of zirconium, hafnium and tin, 0 The entropy-regulated composite dielectric film has high temperature resistance, high breakdown strength, high polarization strength, high energy storage density and good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film preparation, in particular, to an entropy-regulated composite dielectric thin film and a preparation method thereof. BACKGROUND

[0002] Polymer dielectric has good flexibility, easy processing, high breakdown strength and other characteristics, but the dielectric constant is low and the temperature resistance is poor. In order to make up for the defects of single-component polymer dielectric, inorganic fillers are introduced into the polymer dielectric to obtain organic / inorganic composite dielectric materials with high energy storage performance and flexibility, which is one of the main development directions at present. In the related art, the inorganic fillers in the organic / inorganic composite dielectric thin film mainly include two types: high dielectric constant ferroelectric fillers and wide band gap fillers (such as Al2O3, SiO2, BNNS, etc.). The high dielectric constant fillers can effectively improve the dielectric constant of the composite dielectric thin film, but the difference in dielectric constant between the fillers and the polymer matrix is large, which makes the electric field easily concentrate at the interface, resulting in a significant reduction in the breakdown strength of the composite dielectric thin film, and the energy density of the obtained composite dielectric thin film is not effectively improved. The wide band gap fillers can reduce the reduction of the breakdown strength of the composite dielectric thin film or even improve the breakdown strength to some extent, but since the dielectric constant of this type of filler is small (usually <10), the improvement of the polarization strength of the composite dielectric thin film is very limited, resulting in that the energy storage performance of the obtained composite dielectric thin film has not been effectively improved.

[0003] Therefore, the current composite dielectric thin film still needs to be further improved. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art to some extent.

[0005] In one aspect of the present application, an entropy-regulated composite dielectric thin film is provided, comprising: a polymer matrix; a filler dispersed in the polymer matrix, the filler comprising Bi 4-a M 1a Ti (3-3b) M 2b O 12 wherein M1 comprises at least one of lanthanum, neodymium, samarium and praseodymium, M2 comprises at least one of zirconium, hafnium and tin, 0≤a<4, 0<b<1, and the entropy value of the filler is not less than 1.5R. Thus, the entropy-regulated composite dielectric thin film has high temperature resistance, high breakdown strength, high polarization strength, high energy storage density and good stability.

[0006] According to some embodiments of the present application, the filler comprises Bi 3.25 La 0.75 Ti (3-3x) (Zr,Hf,Sn) x O 12wherein 0 < x < 1.

[0007] According to some embodiments of the present application, the volume percentage of the filler is no more than 10% based on the total volume of the polymer matrix.

[0008] According to some embodiments of the present application, the polymer matrix comprises at least one of polyetherimide, polyimide, polypropylene, low-density polyethylene, polyaryletherurethane, polymethyl methacrylate, polyethylene terephthalate, and polycarbonate.

[0009] In another aspect of the present application, a method for preparing the entropy-regulated composite dielectric film is provided, comprising: preparing a filler; preparing a polymer matrix solution, mixing the filler with the polymer matrix solution to obtain a mixed solution; and coating the mixed solution on a pre-cleaned glass sheet, and drying, heating and demolding to obtain the entropy-regulated composite dielectric film. The method for preparing the entropy-regulated composite dielectric film has all the features and advantages of the entropy-regulated composite dielectric film, which will not be repeated here. In general, the method has the advantages of simple process, high-temperature resistance, high breakdown strength, high polarization strength, high energy storage density and good stability.

[0010] According to some embodiments of the present application, the method for preparing the filler comprises: mixing a bismuth precursor salt, a M1 precursor salt, a titanium precursor salt, a M2 precursor salt and a solvent to obtain a precursor solution; mixing the precursor solution with a polymer template to obtain a spinning solution; electrospinning to obtain hybrid nanofibers; and calcining to obtain the filler.

[0011] According to some embodiments of the present application, the calcining process is performed at a heating rate of 1-10 ℃ / min and a temperature of 600-800 ℃.

[0012] According to some embodiments of the present application, the polymer template comprises at least one of polyvinylpyrrolidone and polyethylene oxide.

[0013] According to some embodiments of the present application, the polymer template comprises polyvinylpyrrolidone, and when the precursor solution is mixed with the polyvinylpyrrolidone, (0.6-1) g of the polyvinylpyrrolidone is added per 10 ml of the precursor solution based on the total volume of the precursor solution.

[0014] According to some embodiments of the present application, the polymer template comprises polyethylene oxide, and when the precursor solution is mixed with the polyethylene oxide, (0.03-0.1) g of the polyethylene oxide is added per 10 ml of the precursor solution based on the total volume of the precursor solution.

[0015] According to some embodiments of the present application, after mixing the precursor solution with the polymer template, the polymer template is completely dissolved by heating at a temperature of 50-80°C for 2-12 hours.

[0016] According to some embodiments of the present application, the voltage in the electrospinning process is 10-20 kV.

[0017] According to some embodiments of the present application, the spinning speed in the electrospinning process is 0.1-1.5 mL / h.

[0018] According to some embodiments of the present application, the ambient humidity is not more than 30%.

[0019] According to some embodiments of the present application, in the process of preparing the polymer matrix solution, the mass fraction of the polymer matrix in the polymer matrix solution is 10%-15% based on the total mass of the polymer matrix solution.

[0020] According to some embodiments of the present application, the drying process is performed under vacuum, and the drying temperature is 40-60°C, and the drying time is 2-12 hours.

[0021] According to some embodiments of the present application, in the heating process, the heating temperature is 200-250°C, and the heating time is 1-3 hours.

[0022] According to some embodiments of the present application, the voltage in the electrospinning process is 10-20 kV.

[0023] According to some embodiments of the present application, the spinning speed in the electrospinning process is 0.1-1.5 mL / h.

[0024] According to some embodiments of the present application, the ambient humidity in the electrospinning process is not more than 25%. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings in which:

[0026] Figure 1 A flowchart showing the preparation method of the entropy-regulated composite dielectric film according to an embodiment of the present application is shown in FIG. 1.

[0027] Figure 2 FIG. 2 shows the XRD test graph of the filler prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present application.

[0028] Figure 3The test results of dielectric constant and dielectric loss of the entropy-regulated composite dielectric film prepared in Example 1 of the present application, the composite dielectric films prepared in Comparative Example 1 and Comparative Example 2, and the polyetherimide film in Comparative Example 3 are shown;

[0029] Figure 4 The Weibull distribution of breakdown strength of the entropy-regulated composite dielectric film prepared in Example 1 of the present application, the composite dielectric films prepared in Comparative Example 1 and Comparative Example 2, and the polyetherimide film in Comparative Example 3 are shown;

[0030] Figure 5 The test results of energy density and charge / discharge efficiency of the entropy-regulated composite dielectric film prepared in Example 1 of the present application and the polyetherimide film in Comparative Example 3 are shown;

[0031] Figure 6 The Weibull distribution of breakdown strength of the entropy-regulated composite dielectric film prepared in Example 1 of the present application and the polyetherimide film in Comparative Example 3 under high temperature conditions are shown;

[0032] Figure 7 The test results of energy density and charge / discharge efficiency of the entropy-regulated composite dielectric film prepared in Example 1 of the present application and the polyetherimide film in Comparative Example 3 under high temperature conditions are shown. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described in detail below. The embodiments described below are exemplary only and are not intended to be limiting of the present application. Unless otherwise indicated, technical or scientific terms used in the embodiments have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. The materials, methods, and examples provided are illustrative only and not intended to be limiting.

[0034] In one aspect of the present application, an entropy-regulated composite dielectric film is provided, which comprises a polymer matrix and a filler dispersed in the polymer matrix, the filler comprising Bi 4-a M 1a Ti (3-3b) M 2b O 12 wherein M1 comprises at least one of lanthanum (La), lutetium (Lu), neodymium (Nd), samarium (Sm) and praseodymium (Pr), M2 comprises at least one of zirconium (Zr), hafnium (Hf) and tin (Sn), 0≤a<4, 0<b<1, and the entropy value of the filler is not less than 1.5R. Thus, the entropy-regulated composite dielectric film is resistant to high temperature, has high polarization strength, high energy storage density, good stability, high energy efficiency and high breakdown strength.

[0035] The principles by which this application achieves the aforementioned beneficial effects are explained in detail below:

[0036] As mentioned earlier, in related technologies, when the inorganic filler in the composite dielectric film is a ferroelectric material, the dielectric constant of the undoped ferroelectric material is approximately 260, while the dielectric constant of the polymer matrix is ​​approximately 3.2. The significant difference between these two values ​​leads to electric field accumulation at the interface, making the composite dielectric film prone to breakdown. The entropy-controlled composite dielectric film proposed in this application uses a ferroelectric material as the filler, which is elementally doped and is a high-entropy filler with an entropy value greater than 1.5R. As the entropy value of the filler increases, the dielectric constant decreases significantly, reducing the difference in dielectric constant between the filler and the polymer matrix. This reduces the accumulation of electric field at the interface between the filler and the polymer matrix to some extent. Simultaneously, elemental doping of the filler enhances electron scattering, thereby increasing the breakdown strength of the entropy-controlled composite dielectric film. Furthermore, as the entropy value of the filler increases, the crystal structure of the filler gradually transforms from a ferroelectric phase to a linear pyrochlore phase, and the amorphous content in the filler gradually increases. The resulting high-entropy filler ultimately exhibits a single pyrochlore phase. Figure 2 This allows the filler to have a high intrinsic breakdown strength. When combined with a polymer matrix, it can further enhance the breakdown strength of the entropy-controlled composite dielectric film, and improve the energy density and charge / discharge efficiency of the entropy-controlled composite dielectric film.

[0037] According to some embodiments of the present invention, the filler may include Bi 3.25 La 0.75 Ti (3-3x) (Zr,Hf,Sn) x O 12 , where 0 < x < 1.

[0038] According to some embodiments of the present invention, the specific content of filler in the entropy-controlled composite dielectric film is not particularly limited, and those skilled in the art can design it based on the comprehensive performance of the entropy-controlled composite dielectric film. Specifically, in this application, based on the total volume of the polymer matrix, the volume percentage of filler can be no more than 10%. If the volume percentage of filler is greater than 10%, it will affect the mechanical strength of the entropy-controlled composite dielectric film to a certain extent, affecting film formation and energy storage performance.

[0039] According to some embodiments of the present invention, the materials forming the polymer matrix are not particularly limited, and those skilled in the art can select them by referring to the materials of polymer matrices in related technologies. For example, the materials forming the polymer matrix may include at least one of the following: polyetherimide (PEI), polyimide (PI), polypropylene (BOPP), low-density polyethylene (LDPE), polyarylether urea (PEEU), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polycarbonate (PC).

[0040] In another aspect of the present application, a method for preparing the aforementioned entropy-regulated composite dielectric film is provided, comprising: preparing a filler; preparing a polymer matrix solution, mixing the filler with the polymer matrix solution to obtain a mixed solution; and coating the mixed solution on a pre-cleaned glass sheet, and obtaining the entropy-regulated composite dielectric film through drying, heating and demolding. The entropy-regulated composite dielectric film prepared by the method has all the characteristics and advantages of the aforementioned entropy-regulated composite dielectric film, which will not be repeated here. In general, at least the process is simple, and the prepared entropy-regulated composite dielectric film has high temperature resistance, high polarization strength, high energy storage density, good stability, high energy efficiency and high breakdown strength.

[0041] The steps of the method are described in detail below, with reference to Figure 1 The method comprises:

[0042] S100: preparing a filler

[0043] According to some embodiments of the present application, this step further comprises:

[0044] S110: mixing the bismuth precursor salt, the M1 precursor salt, the titanium precursor salt and the M2 precursor salt with the solvent to obtain a precursor solution. Specifically, the bismuth precursor salt, the M1 precursor salt, the titanium precursor salt and the M2 precursor salt are weighed according to the stoichiometric ratio of each element in the chemical formula of the filler, and the mixed precursor salt is mixed with the solvent to obtain a precursor solution.

[0045] According to some embodiments of the present application, the type of bismuth precursor salt is not particularly limited, for example, it can include at least one of bismuth acetate, bismuth nitrate, bismuth chloride and bismuth sulfate.

[0046] According to some embodiments of the present application, the type of M1 precursor salt is not particularly limited, and the corresponding precursor salt can be selected according to the type of doped element. For example, when M1 is La, the precursor salt can include at least one of lanthanum acetate and lanthanum chloride.

[0047] According to some embodiments of the present application, the type of titanium precursor salt is not particularly limited, for example, it can include at least one of tetrabutyl titanate, tetraethyl titanate and isopropyl titanate.

[0048] According to some embodiments of the present application, the kind of the M2 precursor salt is not particularly limited, and the corresponding precursor salt can be selected according to the kind of the doped element. For example, when M2 includes Zr, Hf and Sn simultaneously, the Zr precursor salt can include at least one of zirconium n-propylate, zirconium sulfate tetrahydrate, zirconium nitrate pentahydrate, the Hf precursor salt can include at least one of hafnium 2,4-pentanedionate, hafnium 1,1'-dipropyl-ferrocene dichloride, hafnium isopropylate, hafnium n-butyrate, and the Sn precursor salt can include at least one of tin acetate, tin (II) chloride dihydrate.

[0049] According to some embodiments of the present application, the kind of the solvent is not particularly limited, and for example, can include at least one of propionic acid, acetic acid, ethanolamine, ethanol, water, N,N dimethylformamide.

[0050] According to some embodiments of the present application, in order to accelerate the dissolution rate of the precursor salt, the precursor solution can also be heated and stirred, and specifically, the heating temperature can be 50-70°C, and the stirring time can be 0.5-10h.

[0051] S120: preparing a spinning solution

[0052] According to some embodiments of the present application, a polymer template is added to the precursor solution to increase the viscosity of the precursor solution, so as to obtain a clear and transparent spinning solution.

[0053] According to some embodiments of the present application, the polymer template can include at least one of polyvinylpyrrolidone (PVP) and polyethylene oxide (PEO). Specifically, when the polymer template is PVP, PVP with a molecular weight of 5-3 million can be selected, and when the polymer template is PEO, PEO with a molecular weight of 30-5 million can be selected. Preferably, the molecular weight of the PVP can be 1.3 million, and the molecular weight of the PEO can be 6 million. For PVP and PEO, if the molecular weight is too large, the PVP and PEO are dissolved slowly, and if the molecular weight is too small, in order to make the viscosity of the spinning solution meet the requirement, the amount of the PVP and PEO will be increased to a certain extent, and after the electrospinning is completed, the content of the PVP or PEO in the nanofiber will be relatively high, which will increase the difficulty of forming the nanofiber after calcination to a certain extent, and the yield of the nanofiber will be reduced.

[0054] According to some embodiments of the present application, the specific amount of polymer template added when mixing the precursor solution with the polymer template is not particularly limited, and one skilled in the art can add the polymer template according to the properties of the solution, such as viscosity. Specifically, when the polymer template is PVP, (0.6-1) g of PVP is added per 10 ml of precursor solution based on the total volume of the precursor solution, and preferably, 0.8 g of PVP is added per 10 ml of precursor solution. When the polymer template is PEO, (0.03-0.1) g of PEO is added per 10 ml of precursor solution based on the total volume of the precursor solution.

[0055] According to some embodiments of the present application, in order to save the time for reaction, the precursor solution can be heated after mixing with the polymer template. The heating temperature can be 50-80°C, and the heating time can be 2-12 h.

[0056] S130: electrospinning

[0057] In this step, the spinning solution obtained in the previous step is injected into a 10 ml syringe for electrospinning.

[0058] According to some embodiments of the present application, the voltage during electrospinning can be 10-20 kV, for example, it can be 11 kV, 12 kV, 13 kV, 14 kV, 15 kV, 16 kV, 17 kV, 18 kV or 19 kV, etc. If the voltage is too small, it will increase the difficulty of forming nanofibers to some extent; if the voltage is too large, the energy consumption is large, which will increase the diameter of the formed nanofibers to some extent.

[0059] According to some embodiments of the present application, the speed of spinning during electrospinning can be 0.1-1.5 mL / h, for example, it can be 0.3 mL / h, 0.5 mL / h, 0.7 mL / h, 0.9 mL / h, 1.1 mL / h or 1.3 mL / h, etc. If the speed of spinning is too small, it will reduce the efficiency of spinning to some extent; if the speed of spinning is too large, it will affect the effect of spinning to some extent, such as the phenomenon of liquid droplets, resulting in the appearance of a solution film and the inability to obtain nanofibers.

[0060] According to some embodiments of the present application, the environmental humidity is not more than 30%. If the environmental humidity is too large, it will increase the risk of the appearance of a solution film of the hybrid nanofiber membrane to some extent, and the hybrid nanofiber cannot be obtained.

[0061] S140: calcination

[0062] In this step, the nanofiber obtained by electrospinning in the previous step is placed in a muffle furnace for calcination to remove the polymer template, and at the same time, the hybrid nanofiber is crystallized to obtain a high-entropy hybrid nanofiber filler with a single linear pyrochlore structure.

[0063] According to some embodiments of the present application, the heating rate of the muffle furnace in the calcination process can be 1-10°C / min, and the temperature can be raised to 600-800°C. For example, the heating rate can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, or 9°C / min. If the heating rate is too slow, it will affect the size of the obtained hybrid nanofiber to some extent, for example, the grain size in the hybrid nanofiber increases, the roughness of the hybrid nanofiber is large, and then affects the density of the composite with the polymer matrix; if the heating rate is too fast, it can cause the polymer template in the hybrid nanofiber to be unable to be completely removed, and then affect the crystallization of the hybrid nanofiber. The heating of the muffle furnace to 600-800°C can make the polymer template completely decomposed.

[0064] S200: preparing a mixed solution of the polymer matrix and the filler

[0065] In this step, a polymer matrix solution is prepared, and the filler is mixed with the polymer matrix solution.

[0066] According to some embodiments of the present application, the material forming the polymer matrix is mixed with the solvent to form a polymer matrix solution. For example, the material forming the polymer matrix can include at least one of PEI, PI, BOPP, LDPE, PEU, PMMA, PET, and PC. According to some specific embodiments of the present application, in the process of preparing the polymer matrix solution, the mass fraction of the polymer matrix in the polymer matrix solution is 10%-15% based on the total mass of the polymer matrix solution. Specifically, when the material forming the polymer matrix is PEI, the PEI is dissolved in NMP under heating to obtain a 12.5wt% PEI / NMP solution.

[0067] According to some embodiments of the present application, the filler is dispersed in the PEI / NMP solution, stirred at 65°C for 1-3h, and broken by a cell disrupter for 5-15min to obtain a uniformly dispersed mixed solution.

[0068] S300: forming an entropy-regulated composite dielectric film

[0069] In this step, the mixed solution is blade-coated on a pre-cleaned glass sheet, dried, heated, and demolded to obtain an entropy-regulated composite dielectric film.

[0070] Specifically, the glass sheet can be placed in a vacuum oven, the heating temperature can be 40-60℃, and the time can be 2-12h; then the glass sheet is placed in a blast oven, the temperature of the blast oven can be 200-250℃, and the time can be 1-3h, and the glass sheet coated with a thin film can be obtained. The glass sheet is placed in deionized water, and the thin film on the surface layer can automatically fall off from the glass sheet and float on the water surface, and the entropy regulation composite dielectric thin film can be obtained.

[0071] Example 1

[0072] 1. 1.3177 g of bismuth acetate, 0.2573 g of lanthanum acetate, 0.5209 g of tetrabutyl titanate, 0.2339 g of zirconium n-propyl alcohol, 0.0.2964 g of hafnium 2,4-pentanedionate and 0.1776 g of tin acetate are weighed in a reagent bottle;

[0073] 2. 10 ml of propionic acid is added to the above-mentioned mixed precursor salt and heated and stirred at 60℃ for 10 minutes to completely dissolve the precursor salt, so as to obtain a clear and transparent precursor solution;

[0074] 3. PVP powder with a molecular weight of 1.3 million is added to the above-mentioned obtained precursor solution, and the specific proportion is that 0.8 g of PVP is added to 10 ml of the precursor solution, and the stirring is continuously carried out at 65℃ for 4h, so as to completely dissolve the PVP, and a clear and transparent spinning solution is obtained;

[0075] 4. The obtained spinning solution is injected into a 10 mL syringe for electrospinning, the spinning voltage is 15 kV, the spinning speed is 1 mL / h, the environmental humidity needs to be lower than 25%, and the environmental temperature is room temperature, and different hybrid nanofibers are obtained;

[0076] 5. The obtained nanofiber is high-temperature calcined, and the calcination process is carried out in a muffle furnace, and the calcination condition is that the temperature is increased to 600℃ at a temperature increasing rate of 2℃ / min from room temperature, and Bi 3.25 La 0.75 Ti 1.5 (Zr, Hf, Sn) 0.5 O 12 filler;

[0077] 6. PEI is dissolved in NMP at 65℃ to obtain a 12.5wt% PEI / NMP solution; then the above-mentioned obtained hybrid nanofiber is dispersed in the PEI / NMP solution at a certain volume ratio, and after magnetic stirring at room temperature for 2h, a cell disruptor is used for dispersion for 10 min, and a uniformly dispersed mixed solution is obtained;

[0078] 7. The mixture obtained above is spread on the pretreated glass sheet by using a doctor blade, and then dried, high-temperature treated and peeled off in sequence to obtain the flexible entropy-regulated composite dielectric film. The drying process is carried out in a vacuum oven at 45°C for 4h, the high-temperature treatment is carried out in a blast oven at 220°C for 2h, and the peeling off is carried out by immersing the glass sheet covered with the film into deionized water for 30min, so that the film on the surface of the glass sheet is automatically peeled off and floats on the water surface, and the Bi 3.25 La 0.75 Ti 1.5 (Zr, Hf, Sn) 0.5 O 12 / PEI entropy-regulated composite dielectric film.

[0079] 8. The obtained entropy-regulated composite dielectric film is dried (80°C blast oven for 2h) to remove the water on the surface, and then electrodes are plated on both sides of the entropy-regulated composite dielectric film by using a film plating machine, so that the test can be carried out.

[0080] Comparative Example 1

[0081] Preparation of Bi 3.25 La 0.75 Ti 2.1 (Zr, Hf, Sn) 0.3 O 12 / PEI composite dielectric film: the remaining steps are referred to Example 1, except that 1.3177g of bismuth acetate, 0.2573g of lanthanum acetate, 0.7293g of tetrabutyl titanate, 0.1434g of zirconium n-propyl alcohol, 0.1778g of hafnium 2,4-pentanedionate and 0.1066g of tin acetate are weighed in a reagent bottle.

[0082] Comparative Example 2

[0083] Preparation of Bi 3.25 La 0.75 Ti3O 12 / PEI composite dielectric film: the remaining steps are referred to Example 1, except that 1.3177g of bismuth acetate, 0.2573g of lanthanum acetate and 1.0418g of tetrabutyl titanate are weighed in a reagent bottle.

[0084] Comparative Example 3

[0085] Preparation of PEI film: PEI is dissolved in NMP at 65°C to obtain a 12.5wt% PEI / NMP solution;

[0086] The solution obtained above was scraped on the pretreated glass sheet by using a doctor blade, and then dried, high-temperature treated and demoulded to obtain a PEI film. The drying process was carried out in a vacuum oven at 45°C for 4h, the high-temperature treatment was carried out in a blast oven at 220°C for 2h, and the demoulding was carried out by immersing the glass sheet covered with the film into deionized water for 30min, so that the film on the surface was automatically separated from the glass sheet and floated on the water surface;

[0087] The PEI film obtained was dried (80°C blast oven for 2h), and then electrodes were plated on both sides of the PEI film by using a film plating machine, so that the test was carried out.

[0088] The Bi 3.25 La 0.75 Ti 1.5 (Zr, Hf, Sn) 0.5 O 12 / PEI entropy-regulated composite dielectric film, the Bi 3.25 La 0.75 Ti 2.1 (Zr, Hf, Sn) 0.3 O 12 / PEI composite dielectric film obtained in Comparative Example 2, the Bi 3.25 La 0.75 Ti3O 12 / PEI composite dielectric film obtained in Example 1 and the PEI film obtained in Comparative Example 3 were subjected to XRD test, dielectric constant and dielectric loss test, breakdown strength test, and calculation of energy density and efficiency, and the test results are shown in Tables 1-4 and Figures 1-4. Figure 2 ~ Appendix Figure 7 .

[0089] Test method:

[0090] 1. XRD test method

[0091] The obtained filler was ground into powder, placed in the groove in the middle of the glass sheet and compacted, and then the glass sheet was placed in the card slot of the X-ray diffractometer for testing. The testing equipment was an X-ray diffractometer of D / max-2550 type from Japan Rikagu Corporation, the test angle range was 10-90°, and the test mode was continuous scanning with a scanning speed of 2° / min.

[0092] 2. Test method of dielectric constant and dielectric loss

[0093] The prepared entropy-regulated composite dielectric film was plated with electrodes on both upper and lower surfaces, and the electrode size was 11mm. Then, the dielectric film was placed on the test sample table for testing. The testing equipment was a broadband dielectric impedance spectrometer from Germany Novocontrol GmbH, and the test frequency range was 10-109Hz. 7Hz, the test temperature can be adjusted within -100-300℃, and the dielectric constant and dielectric loss of the material can be obtained simultaneously during the test.

[0094] 3. Test of breakdown strength

[0095] A voltage is applied to the upper and lower electrodes of the entropy-regulated composite dielectric film, and the test voltage is continuously increased. When the entropy-regulated composite dielectric film is broken down (short circuit occurs in the test circuit), the voltage is the breakdown strength. A series of breakdown strength values are obtained by testing multiple samples at multiple points. Weibull analysis is performed on the breakdown strength values, and the expression is P(E) = 1 - exp(-E / E b )β, E is the breakdown strength value of the test, P(E) is the cumulative breakdown probability under the electric field E, E b is the characteristic breakdown strength, which corresponds to the electric field strength when P(E) is 63.2%. This parameter is usually used to measure the dielectric strength of dielectric materials. β is the Weibull modulus, which reflects the width of the breakdown strength distribution of the material. The test equipment is a charge-discharge tester from Polyk Technologies, and the test temperature can be from room temperature to 200℃.

[0096] 4. Calculation of energy density and efficiency

[0097] The energy density and efficiency are calculated from the polarization-electric field (P-E) loop of the dielectric material.

[0098] Figure 2 In the formula, the configurational entropy is calculated according to the formula: Bi 3.25 La 0.75 Ti (3-3x) (Zr, Hf, Sn) x O 12 When x = 0, the entropy value of the filler is 0.48R, when x = 0.3, the entropy value of the filler is 1.42R, and when x = 0.5, the entropy value of the filler is 1.72R. As can be seen from the attached Figure 3 , it can be seen that as x increases, the crystal structure of the filler gradually transitions from a ferroelectric phase to a linear pyrochlore phase.

[0099] As can be seen from the attached Figure 3 , for the filler alone, the dielectric constant decreases after the ferroelectric material is doped with elements, but compared with the dielectric constant of PEI, the dielectric constant of the filler is still high.

[0100] Figure 4 In the formula, the breakdown strength of PEI is 549 MV / m, and the Weibull modulus is 9.05. The breakdown strength of PEI / Bi 3.25 La 0.75 Ti3O 12The breakdown strength of the entropy-regulated composite dielectric film is 392 MV / m, the Weibull modulus is 6.86, PEI / Bi 3.25 La 0.75 Ti 2.1 (Zr, Hf, Sn) 0.3 O 12 The breakdown strength of the entropy-regulated composite dielectric film is 441 MV / m, the Weibull modulus is 8.05, PEI / Bi 3.25 La 0.75 Ti 1.5 (Zr, Hf, Sn) 0.5 O 12 The breakdown strength of the entropy-regulated composite dielectric film is 610 MV / m, and the Weibull modulus is 11.88. It can be seen that when x is 0.5, the breakdown strength of the entropy-regulated composite dielectric film is the highest, and the stability of the entropy-regulated composite dielectric film is better.

[0101] Figure 5 It can be seen that as the electric field strength increases, the energy density of the entropy-regulated composite dielectric film gradually increases, and the energy density of the entropy-regulated composite dielectric film formed by the high-entropy filler with x being 0.5 is obviously improved, and the charge / discharge efficiency can be maintained at a high level.

[0102] Figure 6 In the present application, the breakdown strength of PEI is 457 MV / m, the Weibull modulus is 7.45, and PEI / Bi 3.25 La 0.75 Ti 1.5 (Zr, Hf, Sn) 0.5 O 12 The breakdown strength of the entropy-regulated composite dielectric film is 590 MV / m, and the Weibull modulus is 13.07. It can be seen that when x is 0.5, the high-entropy filler forms an entropy-regulated composite dielectric film with good high-temperature resistance, high breakdown strength under high-temperature conditions, and good stability.

[0103] By Figure 7 It can be seen that when x is 0.5, even under high-temperature conditions of 150℃, the energy density of the entropy-regulated composite dielectric film is obviously improved, and the charge / discharge efficiency is high.

[0104] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0105] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0106] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0107] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or it can only mean that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or it can only mean that the horizontal height of the first feature is less than that of the second feature.

[0108] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0109] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. An entropy-regulating composite dielectric film, characterized by, The method comprises the following steps: a polymer matrix; a filler dispersed in the polymer matrix, the filler comprising Bi 3.25 La 0.75 Ti (3-3x) (Zr, Hf,Sn) x O 12 wherein 0 < x < 1, the entropy value of the filler is not less than 1.5R, a volume percentage of the filler is not more than 10% based on the total volume of the polymer matrix, the polymer matrix comprises at least one of polyetherimide, polyimide, polypropylene, low-density polyethylene, polyaryletherurethane, polymethyl methacrylate, polyethylene terephthalate and polycarbonate.

2. A method of making the entropy-regulating composite dielectric film of claim 1, characterized by, The method comprises the following steps: preparing a filler; preparing a polymer matrix solution, mixing the filler with the polymer matrix solution to obtain a mixed solution; coating the mixed solution on a pre-cleaned glass sheet, and obtaining the entropy-regulated composite dielectric film through drying, heating and demolding.

3. The method of claim 2, wherein, The method for preparing the filler comprises the following steps: mixing a bismuth precursor salt, a lanthanum precursor salt, a titanium precursor salt, a zirconium precursor salt, a hafnium precursor salt and a tin precursor salt with a solvent to obtain a precursor solution; mixing the precursor solution with a polymer template to obtain a spinning solution; electrospinning to obtain hybrid nanofibers; calcining to obtain the filler.

4. The method of claim 3, wherein, During the calcination process, the heating rate is 1-10 ℃ / min, and the temperature is raised to 600-800 ℃.

5. The method of claim 3, wherein, The polymer template comprises at least one of polyvinylpyrrolidone and polyethylene oxide.

6. The method of claim 5, wherein, When the precursor solution is mixed with the polyvinylpyrrolidone, (0.6-1) g of the polyvinylpyrrolidone is added per 10 ml of the precursor solution based on the total volume of the precursor solution.

7. The method of claim 5, wherein, When the precursor solution is mixed with the polyethylene oxide, (0.03-0.1) g of the polyethylene oxide is added per 10 ml of the precursor solution based on the total volume of the precursor solution.

8. The method of claim 5, wherein, After mixing the precursor solution with the polymer template, heating is performed to completely dissolve the polymer template, the heating temperature is 50-80 ℃, and the heating time is 2-12 h.

9. The method of claim 3, wherein, During the electrospinning process, the voltage is 10-20 kV.

10. The method of claim 9, wherein, During the electrospinning process, the spinning speed is 0.1-1.5 mL / h.

11. The method of claim 9, wherein, During the electrospinning process, the ambient humidity is not more than 30%.

12. The method of claim 2, wherein, During the preparation of the polymer matrix solution, the mass fraction of the polymer matrix in the polymer matrix solution is 10%-15% based on the total mass of the polymer matrix solution.

13. The method of claim 12, wherein, The drying process is performed under vacuum conditions, the drying temperature is 40-60 ℃, and the drying time is 2-12 h.

14. The method of claim 12, wherein, During the heating process, the heating temperature is 200-250 ℃, and the heating time is 1-3 h.

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