A high-entropy ceramic-polymer composite energy storage dielectric thin film material, a preparation method and application thereof

Abstract

The application relates to the technical field of energy storage capacitor dielectric, and discloses a high-entropy ceramic-polymer composite energy storage dielectric film material, a preparation method and application. 0.7 Bi 0.2 TiO3@(Ba 0.25 Ca 0.25 La 0.25 Na 0.25 )TiO3 / PVDF, abbreviated as SBT@BCLNT / PVDF, wherein PVDF is polyvinylidene fluoride, the ratio of BCLNT to SBT is 9wt%-18wt%, and the ratio of SBT@BCLNT to PVDF is 3wt%-12wt%. The SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure is obtained by high-entropy treatment of SBT coated BCLNT; and the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film is prepared by using the PVDF polymer as a matrix material and adopting a casting method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage capacitor dielectric, in particular to a high-entropy ceramic-polymer composite energy storage dielectric film material, a preparation method and an application. BACKGROUND

[0002] In recent years, the demand for electronic devices in portability and functional integration is increasing, which has higher requirements for the energy storage density of the core dielectric material of the electronic device. Compared with single dielectric material, ceramic-polymer composite material has the advantages of high dielectric constant (ε r ) of ceramic material and high breakdown field strength (E b ) of polymer material, which has great potential in improving energy storage density, and thus is widely studied and applied. In order to improve the energy storage density of the dielectric material, a dielectric material with high breakdown field strength (E b ) or high dielectric constant (ε r ) is usually selected. Among polymer materials, PVDF has a higher dielectric constant (~9.8) in a 1 kHz electric field, which is much larger than the dielectric constant of commercial BOPP (~2.2), but the dielectric constant of PVDF still cannot meet the actual demand. Using a polymer with high breakdown field strength as a matrix and an inorganic ceramic material with high dielectric constant as a filler to construct a new composite material is one of the most feasible strategies to improve the energy storage density of dielectric film material.

[0003] The ceramic filler has a significant influence on the energy storage performance of the polymer-based composite dielectric film material. Common fillers include BaTiO3, (Ba 1-x Sr x )TiO3, Na 0.5 Bi 0.5 TiO3 and BiFeO3. These materials are usually used to improve the dielectric constant of polymer-based composite dielectric film material because they have a high dielectric constant value (ε r ). Strontium bismuth titanate (Sr 0.7 Bi 0.2 TiO3, SBT) as a new type of lead-free relaxor ferroelectric ceramic has attracted widespread attention in recent years. Chinese patent document CN112919903B discloses a SBT-based lead-free ceramic material for high-efficiency capacitor and a preparation method thereof, wherein SBT is doped with non-equivalent Bi from strontium titanate, so that SBT retains a simple cubic perovskite structure similar to SrTiO3, and has the characteristics of a fine hysteresis loop of SrTiO3 ceramic. The introduction of Bi 3+ breaks the cis-electric phase in SrTiO3, and under the same electric field, the maximum polarization (P max) and a significant increase in dielectric constant, far higher than traditional linear dielectric. At the same time, SBT exhibits typical relaxation characteristics at room temperature, with high maximum polarization and low residual polarization, high energy storage efficiency, but P max relatively low compared with other relaxor ferroelectric properties, which greatly limits the increase of energy storage density. At the same time, there is a small amount of Bi element volatilization during the sintering process of SBT ceramic, which will produce some oxygen vacancies and lead to lower E b , affecting its energy storage density, which also limits the application of bismuth strontium titanate ceramic in high energy storage density capacitors. Therefore, when SBT is used as an inorganic ceramic filler, further improvement is needed to greatly improve the energy storage performance of polymer-based composite dielectric materials.

[0004] The addition of inorganic ceramic fillers will on the one hand cause some structural defects such as holes and pores in the polymer matrix, inevitably leading to poor processability of the composite material, increased internal defects, sudden drop in mechanical properties, increased leakage current, and rising dielectric loss. This is mainly related to the surface of the inorganic ceramic powder particles and the interface properties between the matrix; on the other hand, due to the large difference in dielectric constant between the filler and the matrix, the local electric field concentration is significantly increased, thereby reducing the E b of the composite material. By constructing a "core-shell" structure, the interface properties of ceramic-polymer composite dielectric energy storage materials can be greatly improved, and the electric field distortion phenomenon of the composite material can be weakened, thereby improving the E b of the material to achieve the purpose of improving energy storage performance. "High-entropy materials" limit the free movement of internal defects to some extent due to their high degree of chemical disorder, thereby improving the dielectric energy storage performance of the material. For example, Chinese patent document CN117735976A discloses a high-entropy energy storage ceramic material based on Bi 0.5 Na 0.5 TiO3, in which Bi, Na, Ba, La, Sr and K are designed at the A site. The doping of Ba 2+ , La 3+ ions is beneficial to reduce the sintering temperature and reduce the grain size, the doping of Sr 2+ ions can enhance the dielectric relaxation characteristics, and the doping of K + ions helps to further destroy the long-range ordered structure and form a polar nanoregion structure, but the energy storage density is only 1.83J / cm 3 , and the performance is still relatively poor. For example, Chinese patent document CN115974548A discloses a lead-free high-entropy ferroelectric film (Bi x Na x K y La y Sr yTiO3 (wherein x>0, y>0, 2x+3y=1) and a preparation method and application thereof, a higher E b And good temperature stability, but still ceramic film its flexibility is very poor, difficult to meet the demand of portable electronic components. Therefore, the high entropy oxide is introduced into the filler, because of its inherent chemical disorder, significant lattice distortion and complex ion valence, it can also improve the element volatilization of the core material, reduce the oxygen vacancy concentration, and open up a new research strategy for high-performance ceramic-polymer composite energy storage dielectric thin film material. At present, the high entropy material with "core-shell" structure as the filler for preparing ceramic-polymer composite energy storage dielectric thin film material has not been reported. SUMMARY

[0005] The purpose of the present application is to provide a high-entropy ceramic material with "core-shell" structure as a filler and a polymer composite dielectric thin film material and a preparation method thereof, to solve the problem of low energy storage performance of the current dielectric thin film.

[0006] The present application prepares SBT powder material as "core" material by chemical precipitation method and high-entropy "shell" layer by sol-gel method to construct SBT@BCLNT high-entropy ceramic filler with "core-shell" structure; at the same time, combined with high-entropy engineering, domain engineering and interface engineering strategies for constructing high-performance energy storage materials, further combined with polymer PVDF to obtain high-performance ceramic-polymer composite flexible dielectric energy storage material, which will have good application prospect.

[0007] The present application solves the above technical problems:

[0008] A high-entropy ceramic-polymer composite energy storage dielectric thin film material and a preparation method thereof, comprising the following steps:

[0009] S1, SBT precursor precipitate is prepared by using TiCl4 solution, Bi(NO3)3 solution and Sr(Ac)2 solution as reactants by precipitation method, and the SBT precursor precipitate is further washed and dried to obtain SBT powder material;

[0010] S2, using the SBT powder material obtained in step S1 as "core" material, BCLNT is prepared by sol-gel method to coat the SBT powder material, so as to obtain SBT@BCLNT high-entropy ceramic filler with "core-shell" structure, and achieve the purpose of high-entropy of BCLNT to SBT powder material;

[0011] S3, the SBT@BCLNT high-entropy ceramic filler with "core-shell" structure obtained in step S2 is added to the PVDF polymer matrix to obtain a coating solution;

[0012] S4, coating the coating film liquid obtained in S3 on a clean glass panel by means of a doctor blade method to obtain a SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film.

[0013] Further limitation, the specific method for preparing the SBT powder material in step S1 is: SBT precursor precipitate is prepared by a precipitation method with TiCl4 solution, Bi(NO3)3 solution and Sr(Ac)2 solution as reactants, and the SBT precursor precipitate is further washed and dried to obtain the SBT powder material.

[0014] Further limitation, the amount of Sr(Ac)2, Bi(NO3)3 and TiCl4 in step S1 is according to Sr 0.7 Bi 0.2 TiO3 stoichiometric ratio 0.7:0.2:1 to prepare SBT precursor precipitate.

[0015] Further limitation, step S2 includes the following steps:

[0016] S21, dissolving tetrabutyl titanate into an ethanol solution;

[0017] S22, sequentially adding acetic acid solution of Ba(NO3)2, aqueous solution of Ca(NO3)2, aqueous solution of La(Ac)3 and aqueous solution of NaNO3 into the solution obtained in step S21, and stirring for 1 h to obtain a mixed solution containing barium, calcium, lanthanum, sodium and titanium ions;

[0018] S23, adding the SBT powder material obtained in step S1 into the mixed solution obtained in step S22, and stirring thoroughly to obtain a turbid solution;

[0019] S24, stirring the turbid solution obtained in step S23 and adding ammonia water to adjust pH=6 to obtain SBT@BCLNT precursor sol;

[0020] S25, gelating the SBT@BCLNT precursor sol obtained in step S24 by water bath heating to obtain a gel;

[0021] S26, drying the gel obtained in step S25 and then calcining to obtain SBT@BCLNT high-entropy ceramic filler powder with "core-shell" structure.

[0022] Further limitation, the amount of tetrabutyl titanate in step S21 and Ba(NO3)2, Ca(NO3)2, La(Ac)3 and NaNO3 in step S22 is according to (Ba 0.25 Ca 0.25 La 0.25 Na 0.25) TiO3 stoichiometric ratio is 1:0.25:0.25:0.25:0.25.

[0023] Further limit, the PVDF is polyvinylidene fluoride.

[0024] Further limit, in the SBT@BCLNT / PVDF high-entropy ceramic-polymer dielectric composite film, the ratio of BCLNT to SBT is 9wt%-18wt%, and the ratio of SBT@BCLNT to PVDF is 3wt%-12wt%.

[0025] A high-entropy ceramic-polymer composite energy storage dielectric thin film material prepared by the preparation method.

[0026] A high-entropy ceramic-polymer composite energy storage dielectric thin film material prepared according to the preparation method of the high-entropy ceramic-polymer composite energy storage dielectric thin film material.

[0027] The application of a high-entropy ceramic-polymer dielectric composite film prepared by the preparation method to high-dielectric energy storage.

[0028] The beneficial effects of the application are:

[0029] The application first prepares SBT powder material by a precipitation method, then performs high-entropy treatment on the SBT powder material by a sol-gel method to obtain SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure, and finally prepares SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film by a casting method; the SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure with high dielectric constant is combined with PVDF with high breakdown strength to achieve the purpose of improving dielectric performance. That is, the interface of the "core-shell" structure helps to improve the breakdown field strength of the composite material, and the fusion of high-entropy dielectric energy storage ceramic filler can improve polarization, so that the energy storage performance of the composite thin film material is improved, and the composite thin film with SBT@BCLNT filler still has good thickness uniformity and flexibility. In short, the dielectric constant of the high-entropy perovskite oxide ceramic as a filler of the dielectric thin film material obtained by the application is as high as 12.2, the breakdown field strength reaches 419.5MV / m, and the maximum energy storage density reaches 9.1J / cm 3 , which is more than 116% higher than that of PVDF, and the energy storage efficiency exceeds 68%. Therefore, the dielectric energy storage performance of the dielectric thin film with SBT@BCLNT high-entropy ceramic as a filler is better, and the performance is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1XRD patterns of SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin films 1, 2, 3 and 4 prepared for Examples 1-4 of the present application and the PVDF dielectric thin film composite material prepared for Comparative Example 1;

[0031] Figure 2 EDS surface element scanning pattern of SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure in Example 3 of the present application, wherein Figure 2 a is the Sr element distribution pattern, Figure 2 b is the Bi element distribution pattern, Figure 2 c is the Na element distribution pattern, Figure 2 d is the Ba element distribution pattern, Figure 2 e is the Ca element distribution pattern, and Figure 2 f is the La element distribution pattern;

[0032] Figure 3 HAADF pattern of SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure in Example 3 of the present application;

[0033] Figure 4 is Figure 3 the element content distribution pattern in the middle green line segment range;

[0034] Figure 5 SEM pattern of SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure in Example 3 of the present application;

[0035] Figure 6 SEM pattern of SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film in Example 3 of the present application;

[0036] Figure 7 TEM pattern of SBT@BCLNT high-entropy ceramic filler in SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film in Example 3 of the present application;

[0037] Figure 8 is Figure 7 an enlarged schematic view of the oval labeled portion;

[0038] Figure 9 Dielectric constant pattern of SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin films prepared for Examples 1-4 of the present application and the PVDF dielectric thin film prepared for Comparative Example 1;

[0039] Figure 10The breakdown field strength diagram of the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film prepared in the embodiments 1-4 of the present application and the PVDF dielectric thin film prepared in the comparative example 1;

[0040] Figure 11 The maximum energy storage density diagram of the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film prepared in the embodiments 1-4 of the present application and the PVDF dielectric thin film prepared in the comparative example 1;

[0041] Figure 12 The energy storage efficiency diagram of the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film prepared in the embodiments 1-4 of the present application and the PVDF dielectric thin film prepared in the comparative example 1. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0043] Embodiment 1

[0044] The present embodiment provides a preparation method of a high-entropy ceramic-polymer composite energy storage dielectric thin film material, specifically:

[0045] S1, 5.99 mL of 1.67 mol / L TiCl4 solution is dropped into 100 mL of 8 mol / L NaOH solution, stirred and heated for 30 min; then 30 mL of Sr(Ac)2 acetic acid aqueous solution is added into the above solution, stirred for 10 min, then 30 mL of Bi(NO3)3 solution is added into the solution, continues to stir for 30 min, then heated to 90℃ at a rate of 2℃ / min, continues to stir for 4 h, then cooled to room temperature, then placed and aged for 24 h, then the precipitate is washed for multiple times until the supernatant is neutral, then the obtained product is dried at 80℃; finally, the white SrBi2Ti2O9 powder, i.e., SBT powder material, is obtained by calcining at 750℃ for 2 h. 0.7 Bi 0.2 TiO3 powder.

[0046] S2, 1 g of SrBi2Ti2O9 powder is added into 15 mL of water and 15 mL of ethanol mixed solution, then the SBT powder suspension is obtained by centrifugal oscillation. 0.7 Bi 0.2 TiO3 powder.

[0047] S3, 0.2565 g of tetrabutyl titanate was dissolved in a mixed solution of 5 mL of ethanol and 5 mL of water, and then a Ba(NO3)2 acetic acid solution (0.0492 g of Ba(NO3)2, 5 mL of ethanol, 5 mL of acetic acid), a Ca(NO3)2 aqueous solution (0.0309 g of Ca(NO3)2, 10 mL of deionized water), a La(Ac)3 solution (prepared by dissolving 0.0614 g of La2O3 in 5 mL of acetic acid and 5 mL of ethanol solution), and a NaNO3 aqueous solution (0.0160 g of NaNO3, 10 mL of deionized water) were sequentially added, stirred for about 1 h, and then the S2-prepared SBT powder suspension was added and stirred rapidly for 2 h; then about 5 mL of ammonia water was added to adjust the pH to about 6, and then the gel was gelled by water bath heating to obtain a turbid gel, the gel was converted into a powder by drying at 80°C, and the obtained powder was calcined at a high temperature of 900°C for 2 h to form SBT@BCLNT high-entropy ceramic filler powder with a "core-shell" structure and a BCLNT coating amount of 13.5 wt%, i.e. high-entropy SBT@BCLNT high-entropy ceramic filler.

[0048] S4, 0.0075 g of SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure was added to 2 mL of N,N-dimethylformamide (DMF) solution, and then ultrasonic oscillation was performed for 1 h; then 0.25 g of PVDF particles were added, ultrasonic dispersion was performed for 25 min and stirring was performed for 24 h, and the slurry was vacuumed at room temperature; finally, under the conditions of adjusting the temperature of the casting machine, the height and moving speed of the doctor blade, the prepared turbid liquid was poured onto an ITO glass plate to form a film, and the coated glass plate was transferred to a vacuum drying oven at 80°C for drying for 50 min to 70 min, and the preferred drying time was 60 min. After taking out, immediately quenching in an ice-water mixture at 0°C, a dense SBT@BCLNT / PVDF composite film was obtained, i.e. SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film, and the sample was recorded as #1.

[0049] Example 2

[0050] The embodiment provides a preparation method of a high-entropy ceramic-polymer composite energy storage dielectric film material, in particular:

[0051] S1, 5.99 mL of 1.67 mol / L TiCl4 solution was dropped into 100 mL of 8 mol / L NaOH solution, stirred and heated for 30 min; then 30 mL of Sr(Ac)2 acetic acid aqueous solution was added into the above solution, stirred for 10 min, then 30 mL of Bi(NO3)3 solution was added into the solution, continued to stir for 30 min, then heated to 90℃ at a rate of 2℃ / min, continued to stir for 4 h, then cooled to room temperature, then aged for 24 h, then the precipitate was washed for several times until the supernatant was neutral, then the obtained product was dried at 80℃; finally, white SrBi2Ti2O9 powder was obtained by calcining at 750℃ for 2 h. 0.7 Bi 0.2 TiO3 powder, i.e. SBT powder material.

[0052] S2, 1 g of SrBi2Ti2O9 powder was added into 15 mL of water and 15 mL of ethanol mixed solution, then SBT powder suspension was obtained by centrifugal oscillation. 0.7 Bi 0.2 TiO3 powder was added into 15 mL of water and 15 mL of ethanol mixed solution, then SBT powder suspension was obtained by centrifugal oscillation.

[0053] S3, 0.2565 g of tetrabutyl titanate was dissolved into 5 mL of ethanol and 5 mL of water mixed solution, then Ba(NO3)2 acetic acid solution (0.0492 g of Ba(NO3)2, 5 mL of ethanol, 5 mL of acetic acid), Ca(NO3)2 aqueous solution (0.0309 g of Ca(NO3)2, 10 mL of deionized water), La(Ac)3 solution (prepared by dissolving 0.0614 g of La2O3 into 5 mL of acetic acid and 5 mL of ethanol solution) and NaNO3 aqueous solution (0.0160 g of NaNO3, 10 mL of deionized water) were added in sequence, stirred for about 1 h, then SBT powder suspension prepared in S2 was added, and stirred rapidly for 2 h; then about 5 mL of ammonia water was added to adjust pH to about 6, then the turbid gel was obtained by gelation through water bath heating, the gel was converted into powder by drying at 80℃, then the obtained powder was calcined at 900℃ for 2 h to form SBT@BCLNT high-entropy ceramic filler with "core-shell" structure and BCLNT coating amount of 13.5 wt%, i.e. high-entropy SBT@BCLNT high-entropy ceramic filler.

[0054] S4, 0.0150 g of SBT@BCLNT high-entropy ceramic filler with "core-shell" structure was added into 2 mL of DMF solution, followed by ultrasonic oscillation for 1 h; then 0.25 g of PVDF particles was added thereto, ultrasonic dispersion for 25 min and stirring for 24 h, and the slurry was vacuumed at room temperature; finally, the prepared turbid liquid was poured onto an ITO glass plate to form a film under the conditions of adjusting the temperature of the casting machine, the height and moving speed of the doctor blade, and the glass plate was transferred to a vacuum drying oven at 80℃ for drying for 50 min-70 min, preferably for 60 min. After taking out, it was immediately quenched in an ice-water mixture at 0℃ to obtain a dense SBT@BCLNT / PVDF composite film, i.e. SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film, which was marked as #2.

[0055] Example 3

[0056] The embodiment provides a preparation method of a high-entropy ceramic-polymer composite energy storage dielectric film material, in particular:

[0057] S1, 5.99 mL of 1.67 mol / L TiCl4 solution was added dropwise into 100 mL of 8 mol / L NaOH solution, stirred and heated for 30 min; then 30 mL of Sr(Ac)2 acetic acid aqueous solution was added dropwise into the above solution, stirred for 10 min, and then 30 mL of Bi(NO3)3 solution was added dropwise into the solution, and the temperature was increased to 90℃ at a rate of 2℃ / min, and the stirring was continued for 4 h, and then cooled to room temperature, and then aged for 24 h, and then the precipitate was washed for multiple times until the supernatant was neutral, and then the obtained product was dried at 80℃; finally, the white Sr 0.7 Bi 0.2 TiO3 powder, i.e. SBT powder material.

[0058] S2, 1 g of Sr 0.7 Bi 0.2 TiO3 powder was added into 15 mL of water and 15 mL of ethanol mixed solution, and then SBT powder suspension was obtained by centrifugal oscillation.

[0059] S3, 0.2565 g of tetrabutyl titanate was dissolved in a mixed solution of 5 mL of ethanol and 5 mL of water, and then a Ba(NO3)2 acetic acid solution (0.0492 g of Ba(NO3)2, 5 mL of ethanol, 5 mL of acetic acid), a Ca(NO3)2 aqueous solution (0.0309 g of Ca(NO3)2, 10 mL of deionized water), a La(Ac)3 solution (prepared by dissolving 0.0614 g of La2O3 in 5 mL of acetic acid and 5 mL of ethanol solution), and a NaNO3 aqueous solution (0.0160 g of NaNO3, 10 mL of deionized water) were sequentially added, stirred for about 1 h, and then the S2-prepared SBT powder suspension was added and stirred rapidly for 2 h; then about 5 mL of ammonia water was added to adjust the pH to about 6, and then the gel was gelled by water bath heating to obtain a turbid gel, the gel was converted into a powder by drying at 80°C, and the obtained powder was calcined at a high temperature of 900°C for 2 h to form SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure and a BCLNT coating amount of 13.5 wt%, i.e., a high-entropy SBT@BCLNT high-entropy ceramic filler.

[0060] S4, 0.0225 g of SBT@BCLNT powder filler with a "core-shell" structure was added to 2 mL of a DMF solution, and then ultrasonic oscillation was performed for 1 h; then 0.25 g of PVDF particles were added, ultrasonic dispersion was performed for 25 min, and stirring was performed for 24 h, and the slurry was vacuumed at room temperature; finally, under the conditions of adjusting the temperature of the casting machine, the height and moving speed of the doctor blade, the prepared turbid liquid was poured onto an ITO glass plate to form a film, and the coated glass plate was transferred to a vacuum drying oven at 80°C for drying for 50 min to 70 min, and the preferred drying time was 60 min. After taking out, immediately quenching in an ice-water mixture at 0°C, a dense SBT@BCLNT / PVDF composite film was obtained, i.e., a SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film, and the sample was recorded as #3.

[0061] Example 4

[0062] The embodiment provides a preparation method of a high-entropy ceramic-polymer composite energy storage dielectric film material, in particular:

[0063] S1, 5.99 mL of 1.67 mol / L TiCl4 solution was dropped into 100 mL of 8 mol / L NaOH solution, stirred and heated for 30 min; then 30 mL of Sr(Ac)2 acetic acid aqueous solution was added into the above solution, stirred for 10 min, then 30 mL of Bi(NO3)3 solution was added into the solution, continued to stir for 30 min, then heated to 90℃ at a rate of 2℃ / min, continued to stir for 4 h, then cooled to room temperature, then aged for 24 h, then the precipitate was washed for several times until the supernatant was neutral, then the obtained product was dried at 80℃; finally, the white Sr 0.7 Bi 0.2 TiO3 powder, i.e. SBT powder material.

[0064] S2, 1 g of Sr 0.7 Bi 0.2 TiO3 powder was added into 15 mL of water and 15 mL of ethanol mixed solution, then SBT powder suspension was obtained by centrifugal oscillation.

[0065] S3, 0.2565 g of tetrabutyl titanate was dissolved into 5 mL of ethanol and 5 mL of water mixed solution, then Ba(NO3)2 acetic acid solution (0.0492 g of Ba(NO3)2, 5 mL of ethanol, 5 mL of acetic acid), Ca(NO3)2 aqueous solution (0.0309 g of Ca(NO3)2, 10 mL of deionized water), La(Ac)3 solution (prepared by dissolving 0.0614 g of La2O3 into 5 mL of acetic acid and 5 mL of ethanol solution) and NaNO3 aqueous solution (0.0160 g of NaNO3, 10 mL of deionized water) were added in sequence, then stirred for about 1 h, then the SBT powder suspension prepared in S2 was added, and stirred rapidly for 2 h; then about 5 mL of ammonia water was added to adjust pH to about 6, then the turbid gel was obtained by gelation through water bath heating, the gel was converted into powder by drying at 80℃, then the obtained powder was calcined at a high temperature of 900℃ for 2 h to form SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure and a BCLNT coating amount of 13.5 wt%, i.e. high-entropy SBT@BCLNT high-entropy ceramic filler.

[0066] S4, 0.0300 g of SBT@BCLNT powder filler with a "core-shell" structure was added to 2 mL of DMF solution, followed by ultrasonic oscillation for 1 h; then 0.25 g of PVDF particles was added thereto, ultrasonic dispersion was performed for 25 min and stirring was performed for 24 h, and the slurry was vacuumed at room temperature; finally, under the condition that the temperature of the casting machine, the height and moving speed of the doctor blade were adjusted, the prepared turbid liquid was poured onto an ITO glass plate to form a film, the coated glass plate was transferred to a vacuum drying oven at 80°C to dry for 50 min-70 min, and preferably for 60 min. After being taken out, it was immediately quenched in an ice water mixture at 0°C to obtain a dense SBT@BCLNT / PVDF composite film, that is, a SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film, which is marked as #4.

[0067] The SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric films prepared in Examples 1-4 above (samples marked #1, #2, #3 and #4 in turn) have good dielectric properties and energy storage properties, can improve the breakdown field strength after high-entropy, and significantly improve the energy storage density, so as to improve the dielectric energy storage performance of the dielectric capacitor.

[0068] The SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric films prepared in Examples 1-4 above are applied in high-dielectric energy storage.

[0069] In order to illustrate the technical advantages of the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric film material of the present application, the physicochemical properties thereof were also tested and verified, and the specific experiments are as follows:

[0070] Comparative Example 1

[0071] 0.25 g of PVDF particles was added to 2 mL of DMF solution, then ultrasonic dispersion was performed for 25 min and stirring was performed for 24 h, and the slurry was vacuumed at room temperature. Then, under the condition that the temperature of the casting machine, the height and moving speed of the doctor blade were adjusted, the prepared suspension was poured onto an ITO glass plate to form a film. The coated glass plate was transferred to a vacuum drying oven at 80°C to form a film. After being taken out, it was immediately quenched in ice water at 0°C to obtain a PVDF film sample.

[0072] Experiment 1

[0073] The SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric films prepared by Examples 1-4 were compared with the PVDF film prepared by Comparative Example 1 by using bulk XRD analysis:

[0074] The phase composition of the ceramic sheet was directly detected by powder X-ray diffraction (XRD). The test conditions were: Cu-Kα target as the ray source, test tube voltage of 40kV, test tube current of 40mA, scanning step of 0.02°, scanning rate of 0.05° / s, and analysis with Jade software. The results are as follows: Figure 1 shown.

[0075] pass Figure 1 It can be seen that the SBT@BCLNT / PVDF high entropy ceramic-polymer composite energy storage dielectric films prepared by Examples 1 to 4 contain strong perovskite phase diffraction peaks in addition to the PVDF-specific phase structure diffraction peaks.

[0076] from Figure 1 It can also be seen that the prepared PVDF-based composite films all contain the three phases of α, β, and γ of PVDF. At the same time, the characteristic peaks of the SBT@BCLNT filler with a "core-shell" structure are clearly detected: at 22.1°, 31.3°, 38.6°, 44.9°, 50.6°, 55.8°, 65.4°, 70°, 74.4°, and 78.8°, corresponding to the characteristic diffraction peaks of (100), (110), (111), (200), (210), (211), (210), and (220), respectively. This shows that the SBT@BCLNT with a "core-shell" structure and PVDF both exist and do not affect each other, thereby maintaining their respective dielectric constants.

[0077] Experiment 2

[0078] The SBT@BCLNT powder particles with a "core-shell" structure prepared in Example 3 of the present invention were dispersed in the solvent ethanol. After dilution, a small amount of liquid was added to the copper mesh using a pipette and then dried for about 1 hour. Energy dispersive X-ray spectrometer (EDS) was used to perform EDS surface element scanning. The results are as follows: Figure 2 shown.

[0079] pass Figure 2 a~ Figure 2 f It can be seen that Ba, Ca, La and Na elements are concentrated in the "shell" layer, while Sr and Bi are distributed in the "core" position, indicating that the high-entropy perovskite oxide BCLNT has been successfully coated on the outer layer of SBT. The SBT@BCLNT high-entropy ceramic filler powder with a "core-shell" structure obtained by step S3 meets the "core-shell" structure.

[0080] Experiment 3

[0081] The SBT@BCLNT powder particles with the 'core-shell' structure prepared in the embodiment 3 of the present application are dispersed in solvent ethanol, and after dilution, a small amount of liquid is added dropwise on a copper mesh using a pipette, and then dried for about 1h. Transmission electron microscopy (TEM) is used for HAADF observation, and the results are shown in Figure 3 .

[0082] From Figure 4 It can be seen that the element content of the SBT@BCLNT powder particles with the 'core-shell' structure along the green line segment is higher in Sr element and Bi content near the center of the SBT@BCLNT powder particles with the 'core-shell' structure, and gradually increases in Ba, Ca, La and Na elements in the center of the SBT@BCLNT powder particles with the 'core-shell' structure, further indicating that the SBT@BCLNT high-entropy ceramic filler obtained by step S3 satisfies the 'core-shell' structure. Figure 3 Experiment 4

[0083] The SBT@BCLNT powder particles with the 'core-shell' structure prepared in the embodiment 3 of the present application are observed by SEM, and the results are shown in

[0084] . Figure 5

[0085] From Figure 5 It can be seen that the SBT@BCLNT powder particles with the 'core-shell' structure all present spherical morphology, and the spherical particles are uniformly dispersed, and by statistics, the particle size size ratio distribution of the spherical particles is shown in Table 1:

[0086] Table 1 Particle size size ratio distribution of SBT@BCLNT powder with the 'core-shell' structure

[0087]

[0088] The average particle size of the SBT@BCLNT powder particles with the 'core-shell' structure is calculated to be 440nm.

[0089] Therefore, the relaxor ferroelectric SBT is collectively high-entropy, forming a large ion size difference, improving the local chemical disorder, and being capable of improving the breakdown field strength of the material on the basis of maintaining the high stability of the material.

[0090] Experiment 5

[0091] The SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film prepared in the embodiment 3 of the present application is observed by SEM, and the results are shown in Figure 6 .

[0092] From Figure 6 ​It can be seen that the SBT@BCLNT high-entropy ceramic filler with a "core-shell" structure is well dispersed in PVDF and is tightly wrapped by the surrounding polymer matrix without pores, indicating that the film is dense.

[0093] Experiment 6

[0094] The high entropy perovskite oxide ceramic filler prepared in Example 3 of the present invention was observed by TEM. Figure 7 and Figure 8 shown.

[0095] Depend on Figure 7 It can be seen that there is a clear contrast between the inside and the edge of the SBT@BCLNT powder with a "core-shell" structure, that is, a "core-shell" structure is formed. Figure 8 It can be seen that the "shell" layer thickness of SBT@BCLNT powder with a "core-shell" structure is about 20 nm, which is the optimal value.

[0096] Further observation Figure 8 As can be seen from the figure, there is a clear contrast between light and dark inside and at the edge of the powder, and the thickness of the "shell" layer is about 20nm.

[0097] This indicates that the SBT@BCLNT “core-shell” structure was successfully prepared by the sol-gel method.

[0098] Experiment 7

[0099] The SBT@BCLNT / PVDF high entropy ceramic-polymer composite energy storage dielectric films prepared in Examples 1 to 4 of the present invention and the PVDF film prepared in Comparative Example 1 were subjected to high-precision vacuum ion sputtering to prepare gold electrodes with a diameter of 2 mm on both sides. The dielectric properties and energy storage properties were tested using conventional detection methods. The specific results are shown in FIG. Figure 9 、 Figure 10 、 Figure 11 and Figure 12 shown.

[0100] pass Figure 9 、 Figure 10 、 Figure 11 and Figure 12 It can be seen that the SBT@BCLNT high entropy filler with a "core-shell" structure can significantly improve the dielectric properties and energy storage density of the PVDF film. For Example 3, when the SBT@BCLNT content with a "core-shell" structure is 9wt% and the BCLNT coating amount is 13.5wt%, the dielectric constant of the SBT@BCLNT / PVDF high entropy ceramic-polymer composite energy storage dielectric film is 12.2, the breakdown field strength is 419.5MV / m, and the maximum energy storage density is 9.1J / cm 3 and energy storage efficiency of 68.6%.

[0101] Therefore, it can be seen that the maximum energy storage density of the SBT@BCLNT / PVDF dielectric thin film obtained by compounding the SBT@BCLNT with a "core-shell" structure as a filler with the matrix PVDF polymer is increased by 25.8% compared with the dielectric constant of the PVDF dielectric thin film, and the maximum energy storage density is increased by 117%.

[0102] The application improves the breakdown field strength of the composite material by constructing the SBT@BCLNT filler with a "core-shell" structure; the high-entropy ceramic filler can improve the polarization of the composite thin film material, thereby improving the energy storage performance of the composite thin film material. Therefore, the combination of the two characteristics makes the SBT@BCLNT / PVDF composite thin film dielectric material have good dielectric energy storage density, and has good thickness uniformity and flexibility.

[0103] The above examples are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A method for preparing a high-entropy ceramic-polymer composite energy storage dielectric thin film material, characterized in that, It comprises the following steps: S1, preparing SBT powder material, the specific method of preparing SBT powder material is: preparing SBT precursor precipitate by taking TiCl4 solution, Bi(NO3)3 solution and Sr(Ac)2 solution as reactants through precipitation method, and further washing and drying the SBT precursor precipitate to obtain SBT powder material; S2, using SBT powder material obtained in step S1 as "core" material, coating SBT powder material by preparing BCLNT through sol-gel method, so as to obtain SBT@BCLNT high-entropy ceramic filler with "core-shell" structure, and achieve the purpose of high-entropy of BCLNT to SBT powder material; The step S2 comprises the following steps: S21, dissolving tetrabutyl titanate into ethanol solution; S22, adding Ba(NO3)2 acetic acid solution, Ca(NO3)2 aqueous solution, La(Ac)3 aqueous solution and NaNO3 aqueous solution into the solution obtained in step S21 in sequence, and stirring for 1 h to obtain a mixed solution containing barium, calcium, lanthanum, sodium and titanium ions; S23, adding SBT powder material obtained in step S1 into the mixed solution obtained in step S22, and stirring sufficiently to obtain a turbid solution; S24, stirring the turbid solution obtained in step S23 and adding ammonia water to adjust pH to 6 to obtain SBT@BCLNT precursor sol; S25, gelating the SBT@BCLNT precursor sol obtained in step S24 through water bath heating to obtain a gel; S26, drying the gel obtained in step S25 and then calcining to obtain high-entropy SBT@BCLNT high-entropy ceramic filler powder with "core-shell" structure; S3, adding SBT@BCLNT high-entropy ceramic filler with "core-shell" structure obtained in step S2 into PVDF polymer matrix to obtain coating liquid; S4, coating the coating liquid obtained in step S3 on a clean glass panel by means of doctor blade coating to obtain SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film.

2. The method for preparing a high entropy ceramic-polymer composite energy storage dielectric thin film material according to claim 1, characterized in that: The amounts of Sr(Ac)2, Bi(NO3)3 and TiCl4 in the step S1 are matched according to Sr 0.7 Bi 0.2 The SBT precursor precipitate is prepared according to the stoichiometric ratio of 0.7:0.2:1 of Sr:Bi:TiO3.

3. The method for preparing a high entropy ceramic-polymer composite energy storage dielectric thin film material according to claim 1, characterized in that: The stoichiometric ratio of TiO2, Ba(NO3)2, Ca(NO3)2, La(Ac)3 and NaNO3 in step S21 is 1:0.25:0.25:0.25:0.

25. 0.25 Ca 0.25 La 0.25 Na 0.25 )TiO3 stoichiometric ratio is 1:0.25:0.25:0.25:0.

25.

4. The method for preparing a high entropy ceramic-polymer composite energy storage dielectric thin film material according to any one of claims 1 to 3, characterized in that: The PVDF is polyvinylidene fluoride.

5. The method for preparing a high entropy ceramic-polymer composite energy storage dielectric thin film material according to claim 1, characterized in that: In the SBT@BCLNT / PVDF high-entropy ceramic-polymer composite energy storage dielectric thin film, the ratio of BCLNT to SBT is 9wt%-18wt%, and the ratio of SBT@BCLNT to PVDF is 3wt%-12wt%.

6. A high-entropy ceramic-polymer composite energy storage dielectric thin film material prepared by the preparation method of any one of claims 1-5.

7. Application of the high-entropy ceramic-polymer composite energy storage dielectric thin film material prepared by the preparation method of any one of claims 1-5 in high-dielectric energy storage.

Images