Multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky micro-crystals and nano-crystals respectively and preparation method of dielectric composite material

Abstract

The invention relates to a multilayer structure dielectric composite material and a preparation method thereof, in particular to a multilayer structure high-temperature and high-performance dielectric composite material embedded with flaky micro-crystals and nano-crystals respectively and a preparation method of the multilayer structure high-temperature and high-performance dielectric composite material. The problems that an existing polymer-based composite material is low in energy storage density at the high temperature, and high energy storage density and high energy storage efficiency at the high temperature are difficult to consider at the same time are solved. The material is of a multi-layer structure formed by alternating NBIT-PEIS-based composite material films and BN-PEIS-based composite material films, the effective energy storage density is larger than or equal to 8.9 J / cm < 3 > under the conditions that the temperature is 150 DEG C and the energy storage efficiency eta is larger than 90%, and the effective energy storage density is larger than or equal to 6.7 J / cm < 3 > under the conditions that the temperature is 200 DEG C and the energy storage efficiency eta is larger than 90%. The method comprises the following steps: 1, preparing a two-dimensional filler NBIT micron sheet; and 2, preparing the polymer-based composite material with the multi-layer structure.

Description

Technical Field

[0001] This invention relates to a multilayer dielectric composite material and its preparation method. Background Technology

[0002] In advanced power electronics systems, the demand for high-temperature resistant polymer-based dielectric energy storage capacitors is increasingly urgent. In applications such as electric vehicles, aerospace systems, and renewable energy generation, capacitors often operate at temperatures exceeding 100°C. For example, electric vehicle inverters can operate at temperatures reaching 140°C to 150°C, and components in aerospace engine control systems may be exposed to temperatures around 200°C for extended periods. However, polymer-based energy storage materials typically face numerous challenges at high temperatures, leading to limitations in their energy storage density (Ua). dis The breakdown strength (E) of the polymer is relatively low. Firstly, high temperatures intensify the movement of polymer molecular chains, leading to an increase in electrical conductivity and consequently reducing the polymer's breakdown strength (E). b The dielectric loss (tan δ) decreases rapidly at high temperatures. Secondly, the increase in dielectric loss (tan δ) at high temperatures may lead to a rapid decrease in remanent polarization (P). r The increase in dielectric constant (ε) leads to a decrease in the energy storage efficiency (η) of the polymer. For example, the widely used biaxially oriented polypropylene (BOPP) film capacitor has a low energy storage efficiency (η < 65%) at 120 °C and can only operate below 105 °C. Third, the dielectric constant (ε) of commonly used dielectric polymers... r The energy density is typically below 4, resulting in a low energy storage density. Currently, the narrow application temperature range and insufficient energy storage performance of polymer materials at high temperatures restrict their application and development in high-temperature, high-performance energy storage devices. Summary of the Invention

[0003] This invention aims to address the problem that existing polymer-based composite materials have low energy storage density at high temperatures, and that it is difficult to simultaneously achieve high energy storage density and high energy storage efficiency at high temperatures. Therefore, it provides a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron and nanocrystals, and its preparation method.

[0004] A multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nano-crystals is a multilayer polymer-based composite material composed of alternating NBIT-PEIS-based composite film and BN-PEIS-based composite film.

[0005] The NBIT-PEIS-based composite membrane is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets, wherein the two-dimensional filler NBIT microsheets are oriented in the membrane, and the normal direction of the sheet is consistent with the thickness direction of the membrane; the BN-PEIS-based composite membrane is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and boron nitride BN nanosheets.

[0006] The two-dimensional filler NBIT micron sheet is Na 0.5 Bi 4.5 Ti4O 15 Micron-sized sheets, with a diameter of 1 µm to 2 µm and an aspect ratio of ≥5 for the two-dimensional filler NBIT micron-sized sheets;

[0007] The boron nitride (BN) nanosheets have a diameter of 50 nm to 500 nm and an aspect ratio of ≥10.

[0008] The NBIT-PEIS-based composite membrane contains 0.15% to 0.95% by mass of NBIT microsheets as the two-dimensional filler; the BN-PEIS-based composite membrane contains 0.15% to 0.95% by mass of boron nitride (BN) nanosheets as the boron nitride (BN)-based composite membrane.

[0009] The aforementioned multilayer high-temperature high-performance dielectric composite material, with embedded sheet-like micron and nanocrystals respectively, exhibits an effective energy storage density ≥8.9 J / cm³ under conditions of 150 °C and energy storage efficiency η > 90%. 3 Under conditions of 200 ℃ and energy storage efficiency η > 90%, the effective energy storage density is ≥ 6.7 J / cm³. 3 .

[0010] A method for preparing a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nanocrystals, comprising the following steps:

[0011] I. Preparation of two-dimensional filler NBIT microsheets:

[0012] According to the chemical formula Na 0.5 Bi 4.5 Ti4O 15 The raw materials were weighed according to the stoichiometric ratio, and the molten salt was weighed according to the mass ratio of raw materials to molten salt of 1:(1~20). The two-dimensional filler NBIT microsheets were prepared by the molten salt growth method.

[0013] II. Preparation of multilayer polymer-based composite materials:

[0014] NBIT-PEIS suspension and BN-PEIS suspension were prepared using two-dimensional filler NBIT microsheets, boron nitride (BN) nanosheets, polyetherimide-copolymer-polysulfone (PEIS) and solvent, respectively. The NBIT-PEIS suspension was cast onto a substrate and vacuum dried to obtain an NBIT-PEIS-based composite film. Then, the BN-PEIS suspension was cast onto the NBIT-PEIS-based composite film and vacuum dried to obtain a BN-PEIS-based composite film. The alternating casting process was repeated, and finally the film was removed from the substrate to obtain a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals, respectively.

[0015] Principle: This invention selects materials with a high glass transition temperature (T). g The polymer matrix is ​​polyetherimide-copolymer-polysulfone (PEIS), and two different two-dimensional materials, sodium bismuth titanate (Na), are selected. 0.5 Bi 4.5 Ti4O 15 Using (NBIT) microsheets and boron nitride (BN) nanosheets as fillers, combined with a multilayer bamboo structure design, a polymer-based composite material exhibiting both high energy storage density and high energy storage efficiency at high temperatures has been invented. Specifically: 1. An appropriate amount of high ε-coefficient polymers is introduced into the PEIS matrix. r Two-dimensional micron-scale sheet-like NBIT can improve the overall E of composite materials through the space charge blocking effect. b and ε r 1. Increase the energy storage density of the material at high temperatures; 2. Introducing an appropriate amount of high-k two-dimensional nanosheet BN into the PEIS matrix can significantly increase the thermal conductivity of the composite material, thereby reducing the risk of thermal runaway at high temperatures and improving E. b And η. 3. Two composite materials, NBIT-PEIS and BN-PEIS, are alternately laminated together using a casting process. The interfacial effect of the multi-layer bamboo structure disperses localized high-electric-field regions within the composite material, preventing the formation of extreme electric-field regions. This reduces the risk of premature breakdown due to localized electric field distortion at high temperatures, thus improving the E of the composite material. b Further improvements. This multi-scale synergistic reinforcement design enhances the energy storage performance of the composite material at high temperatures.

[0016] Beneficial effects of this invention:

[0017] This invention addresses the problem of low energy storage density and difficulty in simultaneously achieving high energy storage density and high energy storage efficiency in existing polymer-based composite materials at high temperatures. Based on the functional synergistic gain of two-dimensional sheet materials of different sizes and compositions, and a multi-scale structure design similar to bamboo, a multi-layer polymer-based composite material with alternating NBIT-PEIS and BN-PEIS-based composite films was developed. Specifically, this invention leverages the space charge blocking effect of NBIT microsheets, the ultra-high thermal conductivity of BN nanosheets, and the interface effect of the multi-layer bamboo structure to synergistically enhance the breakdown field strength (E0) of the material. b ), dielectric constant (ε) r Based on the properties of heat and thermal conductivity (k), a capacitor with both high energy density and high energy storage efficiency at high temperatures was fabricated. Under conditions of 150 °C and energy storage efficiency η > 90%, the effective energy storage density was ≥ 8.9 J / cm³. 3 Under conditions of 200 ℃ and energy storage efficiency η > 90%, the effective energy storage density is ≥ 6.7 J / cm³. 3 Furthermore, the cyclic fast charge-discharge test results of this composite material show that, under conditions of 200 ℃ and 2000 kV / cm, the charge-discharge rate is ≤30 ns and the power density is ≥25.0 MW / cm². 3 Furthermore, its energy storage performance shows no degradation even after 10,000 long-term cycles. The preparation process of this invention is simple and efficient, and the developed high-temperature, high-performance polymer-based composite material is expected to find wide application in the field of high-temperature, high-performance polymer capacitors, showing a bright future. Attached Figure Description

[0018] Figure 1 The images are scanning electron microscope images. a shows the two-dimensional filler NBIT microsheets and their arrangement and dispersion in PEIS in step two ① of Example 1, and b shows the boron nitride BN nanosheets and their arrangement and dispersion in PEIS in step two ② of Example 1.

[0019] Figure 2 Hysteresis loops of pure PEIS, BN-PEIS and NBIT-PEIS at temperatures of 150 ℃ and 200 ℃, respectively. a represents 150 ℃ and b represents 200 ℃.

[0020] Figure 3 Microscopic morphology of the PEIS-6 cross section prepared in Example 1;

[0021] Figure 4 Hysteresis loops of dielectric energy storage composite materials with different numbers of layers prepared in Examples 1 to 2 and comparative experiments at temperatures of 150 ℃ or 200 ℃ are shown. a represents 150 ℃ and b represents 200 ℃.

[0022] Figure 5 The charge-discharge rate diagram and cycle stability diagram of pure PEIS and PEIS-6 prepared in Example 1 are shown under the conditions of temperature of 200 ℃ and electric field of 2000 kV / cm. a is the charge-discharge rate diagram and b is the cycle stability diagram.

[0023] Figure 6 The breakdown field strength of pure PEIS, BN-PEIS, NBIT-PEIS and PEIS-6 prepared in Example 1 at 150 °C or 200 °C.

[0024] Figure 7 The relative permittivity of pure PEIS, BN-PEIS, NBIT-PEIS and PEIS-6 prepared in Example 1 at 150 °C or 200 °C;

[0025] Figure 8 The thermal conductivity of pure PEIS, BN-PEIS, NBIT-PEIS and PEIS-6 prepared in Example 1 at 150 °C or 200 °C;

[0026] Figure 9 The hysteresis loop of PEIS-6 prepared in Example 1 changes from room temperature to high temperature. Detailed Implementation

[0027] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0028] Specific implementation method one: This implementation method is a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron crystals and nano crystals respectively. It is a multilayer polymer-based composite material composed of alternating NBIT-PEIS-based composite film and BN-PEIS-based composite film.

[0029] The NBIT-PEIS-based composite membrane is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets, wherein the two-dimensional filler NBIT microsheets are oriented in the membrane, and the normal direction of the sheet is consistent with the thickness direction of the membrane; the BN-PEIS-based composite membrane is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and boron nitride BN nanosheets.

[0030] The two-dimensional filler NBIT micron sheet is Na 0.5 Bi 4.5 Ti4O 15 Micron-sized sheets, with a diameter of 1 µm to 2 µm and an aspect ratio of ≥5 for the two-dimensional filler NBIT micron-sized sheets;

[0031] The boron nitride (BN) nanosheets have a diameter of 50 nm to 500 nm and an aspect ratio of ≥10.

[0032] The NBIT-PEIS-based composite membrane contains 0.15% to 0.95% by mass of NBIT microsheets as the two-dimensional filler; the BN-PEIS-based composite membrane contains 0.15% to 0.95% by mass of boron nitride (BN) nanosheets as the boron nitride (BN)-based composite membrane.

[0033] The aforementioned multilayer high-temperature high-performance dielectric composite material, with embedded sheet-like micron and nanocrystals respectively, exhibits an effective energy storage density ≥8.9 J / cm³ under conditions of 150 °C and energy storage efficiency η > 90%. 3 Under conditions of 200 ℃ and energy storage efficiency η > 90%, the effective energy storage density is ≥ 6.7 J / cm³. 3 .

[0034] The beneficial effects of this specific implementation method are:

[0035] This specific embodiment aims to address the problem that existing polymer-based composite materials suffer from low energy storage density at high temperatures and the difficulty in simultaneously achieving high energy storage density and high energy storage efficiency at high temperatures. Based on the functional synergistic gain of two-dimensional sheet materials of different sizes and compositions, and a multi-scale structure design similar to bamboo, a multi-layer polymer-based composite material with alternating NBIT-PEIS-based and BN-PEIS-based composite film was developed through multi-scale control. Specifically, this embodiment leverages the space charge blocking effect of NBIT microsheets, the ultra-high thermal conductivity of BN nanosheets, and the multi-layer bamboo-like interface effect to synergistically enhance the breakdown field strength (E0) of the material. b ), dielectric constant (ε) r Based on the properties of heat and thermal conductivity (k), a capacitor with both high energy density and high energy storage efficiency at high temperatures was fabricated. Under conditions of 150 °C and energy storage efficiency η > 90%, the effective energy storage density was ≥ 8.9 J / cm³. 3 Under conditions of 200 ℃ and energy storage efficiency η > 90%, the effective energy storage density is ≥ 6.7 J / cm³. 3 Furthermore, the cyclic fast charge-discharge test results of this composite material show that, under conditions of 200 ℃ and 2000 kV / cm, the charge-discharge rate is ≤30 ns and the power density is ≥25.0 MW / cm². 3 Furthermore, its energy storage performance shows no degradation even after 10,000 long-term cycles. The preparation process described in this specific embodiment is simple and efficient, and the developed high-temperature, high-performance polymer-based composite material is expected to find wide application in the field of high-temperature, high-performance polymer capacitors, showing a bright future.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the multilayer high-temperature high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals is a polymer-based composite material with two or more layers, consisting of alternating layers of NBIT-PEIS-based composite material films with a thickness of 1 μm to 5 μm and BN-PEIS-based composite material films with a thickness of 1 μm to 5 μm; the diameter of the two-dimensional filler NBIT microsheets is 1.1 µm to 1.9 µm; and the diameter of the boron nitride (BN) nanosheets is 100 nm to 200 nm. Everything else is the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the total thickness of the multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nanocrystals is 6 μm to 15 μm; the multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nanocrystals exhibits a charge / discharge rate ≤30 ns and a power density ≥25.0 MW / cm² under conditions of 200 ℃ and an electric field of 2000 kV / cm². 3 Furthermore, its energy storage performance shows no degradation even after 10,000 long-term cycles. Everything else is the same as in Specific Implementation Method 1.

[0038] Specific Implementation Method 4: A method for preparing a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nano-crystals, which is carried out according to the following steps:

[0039] I. Preparation of two-dimensional filler NBIT microsheets:

[0040] According to the chemical formula Na 0.5 Bi 4.5 Ti4O 15 The raw materials were weighed according to the stoichiometric ratio, and the molten salt was weighed according to the mass ratio of raw materials to molten salt of 1:(1~20). The two-dimensional filler NBIT microsheets were prepared by the molten salt growth method.

[0041] II. Preparation of multilayer polymer-based composite materials:

[0042] NBIT-PEIS suspension and BN-PEIS suspension were prepared using two-dimensional filler NBIT microsheets, boron nitride (BN) nanosheets, polyetherimide-copolymer-polysulfone (PEIS) and solvent, respectively. The NBIT-PEIS suspension was cast onto a substrate and vacuum dried to obtain an NBIT-PEIS-based composite film. Then, the BN-PEIS suspension was cast onto the NBIT-PEIS-based composite film and vacuum dried to obtain a BN-PEIS-based composite film. The alternating casting process was repeated, and finally the film was removed from the substrate to obtain a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals, respectively.

[0043] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that: the raw materials mentioned in step one are Na2CO3, Bi2O3, and TiO2; the molten salt mentioned in step one is NaCl; and the purity of the raw materials and molten salt mentioned in step one is ≥99.0%. Everything else is the same as in Specific Implementation Method Four.

[0044] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Four or Five in that the preparation of two-dimensional filler NBIT microsheets using the molten salt growth method described in step one is specifically carried out according to the following steps: using ethanol or water as the ball milling medium and zirconium or agate balls as the grinding balls, the raw materials are mixed with molten salt ball milling for 25 h to 48 h at a rotation speed of 200 r / min to 400 r / min and a ball-to-material mass ratio of 1:(0.1 to 0.5) to obtain a mixture. The mixture is then calcined at a temperature of 810 ℃ to 1000 ℃ for 1.2 h to 4 h, and finally washed and dried to obtain two-dimensional filler NBIT microsheets; the diameter of the grinding balls is 1 mm to 10 mm. Other aspects are the same as in Specific Implementation Method Four or Five.

[0045] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods Four to Six in that the NBIT-PEIS suspension mentioned in step two is specifically prepared according to the following steps:

[0046] Polyetherimide-copolymer-polysulfone (PEIS) solid particles were added to N-methylpyrrolidone and stirred at a speed of 500 r / min to 900 r / min to dissolve them, thus obtaining a PEIS solution. Two-dimensional filler NBIT microsheets were added to N-methylpyrrolidone and sonicated for 30 min to 60 min at a power of 100 W to 480 W to obtain an NBIT solution. The PEIS solution and NBIT solution were mixed at a stirring speed of 500 r / min to 900 r / min for 24 h to 48 h to obtain an NBIT-PEIS suspension. Other steps were the same as in specific embodiments four to six.

[0047] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods Four to Seven in that the BN-PEIS suspension mentioned in step two is specifically prepared according to the following steps:

[0048] Polyetherimide-copolymer-polysulfone (PEIS) solid particles were added to N-methylpyrrolidone and stirred at a speed of 500 r / min to 900 r / min to dissolve them, thus obtaining a PEIS solution. Boron nitride (BN) nanosheets were added to N-methylpyrrolidone and sonicated for 30 min to 60 min at a power of 100 W to 480 W to obtain a BN solution. The PEIS solution and BN solution were mixed at a stirring speed of 500 r / min to 900 r / min for 24 h to 48 h to obtain a BN-PEIS suspension. Other steps were the same as in specific embodiments four to seven.

[0049] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Four to Eight in that: the total concentration of polyetherimide-copolymer-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets in the NBIT-PEIS suspension in step two is 0.12 g / mL to 0.18 g / mL; the total concentration of polyetherimide-copolymer-polysulfone polymer PEIS and boron nitride BN nanosheets in the BN-PEIS suspension in step two is 0.12 g / mL to 0.18 g / mL. Everything else is the same as in Specific Implementation Methods Four to Eight.

[0050] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Four to Nine in that: the substrate mentioned in step two is a pre-treated glass substrate, and the pre-treatment is carried out according to the following steps: using a plasma cleaner, under air atmosphere and power conditions of 10.2 W to 29.6 W, cleaning for 5 min to 10 min; the casting process mentioned in step two specifically involves casting using a casting machine at a casting speed of 0.1 cm / s to 1.0 cm / s; the vacuum drying process mentioned in step two specifically involves vacuum drying at a temperature of 50 ℃ to 120 ℃ for 2 h to 12 h. The rest is the same as in Specific Implementation Methods Four to Nine.

[0051] The purpose of the pretreatment of the glass substrate by the plasma cleaner in this specific embodiment is to form a layer of plasma oxygen on the surface of the glass substrate, which helps the suspension to be more evenly and smoothly dispersed on the entire substrate surface, avoiding local insufficient or excessive liquid.

[0052] The beneficial effects of the present invention are verified by the following embodiments:

[0053] Example 1:

[0054] A method for preparing a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nanocrystals, comprising the following steps:

[0055] I. Preparation of two-dimensional filler NBIT microsheets:

[0056] According to the chemical formula Na 0.5 Bi 4.5 Ti4O 15 The raw materials were weighed according to the stoichiometric ratio, and the molten salt was weighed according to the mass ratio of raw materials to molten salt of 1:15. Using ethanol as the ball milling medium and zirconium balls as the grinding balls, the raw materials and molten salt were ball milled and mixed for 36 h at a rotation speed of 300 r / min and a ball-to-material mass ratio of 1:0.3 to obtain a mixture. The mixture was calcined at a temperature of 850 ℃ for 1.5 h, and finally washed and dried to obtain two-dimensional filler NBIT micron sheets.

[0057] The raw materials are Na2CO3, Bi2O3, and TiO2; the molten salt is NaCl; the purity of Na2CO3 is 99.5%; the purity of Bi2O3 is ≥99.9%; the purity of TiO2 is ≥99.0%; the purity of NaCl is ≥99.5%; the diameter of the grinding ball is 2 mm; the diameter of the two-dimensional filler NBIT micron sheet is 1.1 µm~1.9 µm, and the aspect ratio is ≥5.

[0058] II. Preparation of multilayer polymer-based composite materials:

[0059] ① Polyetherimide-copolymer-polysulfone polymer PEIS solid particles were added to N-methylpyrrolidone (NMP, 99.5%) and stirred for 4 h at a stirring speed of 800 r / min until completely dissolved to obtain a PEIS solution; two-dimensional filler NBIT microsheets were added to N-methylpyrrolidone and sonicated for 40 min to obtain an NBIT solution; the PEIS solution and NBIT solution were mixed for 36 h at a stirring speed of 800 r / min to obtain an NBIT-PEIS suspension.

[0060] The total concentration of polyetherimide-copoly-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets in the NBIT-PEIS suspension is 0.14 g / mL;

[0061] ② Polyetherimide-copolymer-polysulfone (PEIS) solid particles were added to N-methylpyrrolidone (NMP, 99.5%) and stirred for 4 h at a stirring speed of 800 r / min until completely dissolved to obtain a PEIS solution. Boron nitride (BN) nanosheets were added to N-methylpyrrolidone and sonicated for 40 min to obtain a BN solution. The PEIS solution and BN solution were mixed at a stirring speed of 800 r / min for 36 h to obtain a BN-PEIS suspension. The boron nitride (BN) nanosheets had a sheet diameter of 100 nm to 200 nm and an aspect ratio ≥10.

[0062] The total concentration of polyetherimide-copoly-polysulfone polymer PEIS and boron nitride BN nanosheets in the BN-PEIS suspension is 0.14 g / mL;

[0063] ③ Under the condition of a casting speed of 0.5 cm / s, the NBIT-PEIS suspension was cast onto a glass substrate using a casting machine. After vacuum drying at a temperature of 70 ℃ for 12 h, an NBIT-PEIS-based composite film was obtained. Then, under the condition of a casting speed of 0.5 cm / s, the BN-PEIS suspension was cast onto the NBIT-PEIS-based composite film using a casting machine. After vacuum drying at a temperature of 70 ℃ for 12 h, a BN-PEIS-based composite film was obtained. The alternating casting process was repeated, and finally the film was removed from the substrate to obtain a multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron and nanocrystals, namely a 6-layer dielectric energy storage composite material, named PEIS-6, and covered with an Au electrode with a diameter of 2 mm for measuring electrical performance.

[0064] The thickness of the NBIT-PEIS-based composite material membrane is 1.3 μm to 1.6 μm; the thickness of the BN-PEIS-based composite material membrane is 1.3 μm to 1.6 μm; the mass percentage of the two-dimensional filler NBIT microsheets in the NBIT-PEIS-based composite material membrane is 0.75%; the mass percentage of boron nitride (BN) nanosheets in the BN-PEIS-based composite material membrane is 0.75%; and the total thickness of the multilayer high-temperature high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals is approximately 8 μm to 10 μm.

[0065] The substrate mentioned in step 2③ is a pre-treated glass substrate, and the pretreatment is carried out according to the following steps: using a PCE-6 small plasma cleaner, under air atmosphere and power of 20 W, cleaning for 10 min.

[0066] Example 1 describes a multilayer high-temperature, high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals. This material is a six-layer polymer-based composite material composed of alternating NBIT-PEIS-based and BN-PEIS-based composite films. The NBIT-PEIS-based composite film is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets, wherein the two-dimensional filler NBIT microsheets are oriented in the film, with their normal direction aligned with the thickness direction of the film. The BN-PEIS-based composite film is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and boron nitride (BN) nanosheets. The two-dimensional filler NBIT microsheets are Na... 0.5 Bi 4.5 Ti4O 15 The micron-sized sheets, wherein the diameter of the two-dimensional filler NBIT micron-sized sheets is 1.1 µm to 1.9 µm and the aspect ratio is ≥5; the diameter of the boron nitride (BN) nanosheets is 100 nm to 200 nm and the aspect ratio is ≥10.

[0067] The NBIT-PEIS-based composite membrane contains 0.75% by mass of NBIT microsheets as two-dimensional filler; the BN-PEIS-based composite membrane contains 0.75% by mass of boron nitride (BN) nanosheets as boron nitride.

[0068] The multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron and nanocrystals, respectively, achieves an effective energy storage density of 9.6 J / cm³ under conditions of 150 °C and energy storage efficiency η > 90%. 3 Under conditions of a temperature of 200 ℃ and an energy storage efficiency η > 90%, the effective energy storage density is 7.3 J / cm³. 3 ;

[0069] The multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron-crystals and nanocrystals exhibits a charge-discharge rate of 29 ns and a power density of 30.2 MW / cm² under conditions of 200 ℃ and an electric field of 2000 kV / cm. 3 Furthermore, its energy storage performance remains undiminished even after 10,000 long-term cycles.

[0070] The polyetherimide-copoly-polysulfone polymer (PEIS) solid particles described in this embodiment were purchased from PolyK Company, USA. The product model is PEI265, and its performance parameters include glass transition temperature T0. g Approximately 265 ℃, structural formula:

[0071] .

[0072] Figure 1The images are scanning electron microscope (SEM) images. Image a shows the two-dimensional filler NBIT microsheets and their arrangement and dispersion in PEIS in step two ① of Example 1, and image b shows the boron nitride (BN) nanosheets and their arrangement and dispersion in PEIS in step two ② of Example 1. As can be seen from the images, the diameter of the two-dimensional filler NBIT microsheets is about 1.1 µm to 1.9 µm, and the diameter of the boron nitride (BN) nanosheets is about 100 nm to 200 nm, and they are randomly dispersed in the polymer matrix.

[0073] According to international practice, for capacitors used in high-temperature environments, in order to avoid the energy loss of the capacitors themselves being converted into Joule heat and causing a vicious cycle, their energy storage performance is usually measured at an energy storage efficiency of over 90%. Therefore, using the NBIT-PEIS suspension prepared in step two ① of Example 1, it was cast onto a glass substrate using a casting machine at a casting speed of 0.5 cm / s, and then vacuum dried at 70 ℃ for 12 h to obtain an NBIT-PEIS-based composite single film (thickness of 8 μm~10 μm), named NBIT-PEIS; using the BN-PEIS suspension prepared in step two ② of Example 1, it was cast onto a glass substrate using a casting machine at a casting speed of 0.5 cm / s, and then vacuum dried at 70 ℃ for 12 h to obtain a BN-PEIS-based composite single film (thickness of 8 μm~10 μm), named BN-PEIS; pure PEIS (thickness of 8 μm~10 μm), the NBIT-PEIS-based composite single film, and the BN-PEIS-based composite single film were used to cover an Au electrode with a diameter of 2 mm for measuring electrical properties.

[0074] Figure 2Figure a shows the hysteresis loops of pure PEIS, BN-PEIS, and NBIT-PEIS at temperatures of 150 ℃ and 200 ℃, respectively. Figure a represents 150 ℃ and Figure b represents 200 ℃. As can be seen from Figure a, at 150 ℃, the electric field of the BN-PEIS-based composite monolayer increased from 4088 kV / cm to 4785 kV / cm after the introduction of two-dimensional BN nanosheets, which is 1.2 times that of pure PEIS. This is mainly because the introduction of BN improves the thermal conductivity of the composite material and alleviates dielectric breakdown caused by long-term Joule heat accumulation. Similarly, the electric field of the NBIT-PEIS-based composite monolayer increased from 4088 kV / cm to 5185 kV / cm after the introduction of two-dimensional NBIT microsheets, which is 1.3 times that of pure PEIS. This is mainly because the two-dimensional sheet-like NBIT exerts a charge barrier effect under high electric fields, increasing the electric field strength of the composite material. Similarly, as shown in Figure b, at 200 °C, after introducing two-dimensional BN nanosheets, the applied electric field of the BN-PEIS-based composite single film increased from 3490 kV / cm to 4188 kV / cm, which is 1.2 times that of pure PEIS. This is mainly because the introduction of BN improves the thermal conductivity of the composite material and alleviates the dielectric breakdown caused by long-term Joule heat accumulation. After introducing two-dimensional NBIT microsheets, the applied electric field of the NBIT-PEIS-based composite single film increased from 3490 kV / cm to 4586 kV / cm, which is 1.3 times that of pure PEIS. Therefore, the energy storage density can be calculated using the following formula:

[0075] (1)

[0076] (2)

[0077] Among them, W rec For effective energy storage density, P max For saturation polarization intensity, P r Where η is the remanent polarization intensity, E is the applied electric field, η is the energy storage efficiency, and W is the remanent polarization intensity. t The total energy storage density is given. It can be calculated that at 150 °C, after introducing two-dimensional BN, the single-film energy storage density of the BN-PEIS-based composite material increases from 4.5 J / cm³. 3 Increased to 6.5 J / cm 3 The energy storage density of NBIT-PEIS-based composite monolayers is increased to 1.4 times that of pure PEIS, from 4.5 J / cm³. 3 Increased to 8.0 J / cm 3 The energy density of the BN-PEIS-based composite single film was increased to 1.8 times that of pure PEIS; in particular, at 200 °C, the energy density of the BN-PEIS-based composite single film increased from 3.1 J / cm³ to 1.8 times that of pure PEIS. 3 Increased to 4.9 J / cm 3The energy storage density of the NBIT-PEIS-based composite monolayer is increased to 1.5 times that of pure PEIS, from 3.1 J / cm³. 3 Increased to 6.2 J / cm 3 The energy storage capacity was increased to 2.0 times that of pure PEIS, indicating that the introduction of BN and NBIT both played an important role in improving the overall energy storage performance of composite materials at high temperatures.

[0078] Example 2: This example differs from Example 1 in that: in step 2.3, alternating casting is repeated to obtain a 4-layer dielectric energy storage composite material, named PEIS-4; the thickness of the NBIT-PEIS-based composite film is 2 μm~2.5 μm; the thickness of the BN-PEIS-based composite film is 2 μm~2.5 μm; the total thickness of the 4-layer dielectric energy storage composite material is 8 μm~10 μm. Everything else is the same as in Example 1.

[0079] Example 2 describes a multilayer high-temperature, high-performance dielectric composite material with embedded sheet-like microcrystals and nanocrystals. This composite material is a four-layer polymer-based composite material consisting of alternating NBIT-PEIS-based and BN-PEIS-based composite films. The NBIT-PEIS-based composite film is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and two-dimensional filler NBIT microsheets, wherein the two-dimensional filler NBIT microsheets are oriented in the film, with their normal direction aligned with the thickness direction of the film. The BN-PEIS-based composite film is prepared from polyetherimide-copolymer-polysulfone polymer PEIS and boron nitride (BN) nanosheets. The two-dimensional filler NBIT microsheets are Na... 0.5 Bi 4.5 Ti4O 15 The micron-sized sheets, wherein the diameter of the two-dimensional filler NBIT micron-sized sheets is 1.1 µm to 1.9 µm and the aspect ratio is ≥5; the diameter of the boron nitride (BN) nanosheets is 100 nm to 200 nm and the aspect ratio is ≥10.

[0080] The NBIT-PEIS-based composite membrane contains 0.75% by mass of NBIT microsheets as two-dimensional filler; the BN-PEIS-based composite membrane contains 0.75% by mass of boron nitride (BN) nanosheets as boron nitride.

[0081] The multilayer high-temperature high-performance dielectric composite material with embedded sheet-like micron and nanocrystals, respectively, achieves an effective energy storage density of 8.9 J / cm³ under conditions of 150 °C and energy storage efficiency η > 90%. 3 Under conditions of 200 ℃ and energy storage efficiency η > 90%, the effective energy storage density is 6.7 J / cm³. 3 .

[0082] Comparative Experiment: This comparative experiment differs from Example 1 in that: in step 2③, a two-layer dielectric energy storage composite material, named PEIS-2, is obtained; the thickness of the NBIT-PEIS-based composite film is 4 μm~5 μm; the thickness of the BN-PEIS-based composite film is 4 μm~5 μm; and the total thickness of the two-layer dielectric energy storage composite material is 8 μm~10 μm. Everything else is the same as in Example 1.

[0083] Figure 3 The image shows the cross-sectional microstructure of the PEIS-6 prepared in Example 1. As can be seen from the figure, the total thickness of this multilayer composite is approximately 9.3 μm. Since all layers use the same matrix, the layers are well bonded together, there are no pores, and the overall morphology is uniform, which provides a basis for its excellent dielectric energy storage performance.

[0084] Figure 4 The figures show the hysteresis loops of dielectric energy storage composite materials with different numbers of layers prepared in Examples 1-2 and the comparative experiment at temperatures of 150 ℃ and 200 ℃, respectively. Figure a represents 150 ℃, and figure b represents 200 ℃. As shown in Figure a, the applied electric fields of the PEIS-2, PEIS-4, and PEIS-6 composite materials at 150 ℃ and with energy storage efficiencies above 90% are 5187 kV / cm, 5585 kV / cm, and 5787 kV / cm, respectively. Calculations show that their energy storage densities are 8.3 J / cm³. 3 8.9 J / cm 3 and 9.6 J / cm 3 As shown in Figure b, the application electric fields of PEIS-2, PEIS-4, and PEIS-6 composite materials at 200 ℃ and with energy storage efficiencies above 90% are 4588 kV / cm, 4887 kV / cm, and 5087 kV / cm, respectively. Calculations show that their energy storage densities are 5.9 J / cm³. 3 6.7 J / cm 3 and 7.3 J / cm 3 The results show that the PEIS-6 composite material exhibits the best energy storage performance, maintaining an energy storage efficiency above 90% and achieving a power of 9.6 J / cm³ at 150 °C. 3 Its energy storage density is 2.1 times that of pure PEIS; it has a strength of 7.3 J / cm³ at 200 °C. 3 The energy storage density is 2.3 times that of pure PEIS, which shows that the composite material design of bamboo structure plays a significant role in improving the energy storage performance of composite materials at high temperatures.

[0085] Figure 5The charge-discharge rate and cycle stability diagrams for pure PEIS and PEIS-6 prepared in Example 1 are shown in Figure a, where a is the charge-discharge rate diagram and b is the cycle stability diagram. Figure a shows that pure PEIS has a discharge rate of 47 ns and a cycle stability of 8.6 MW / cm. 3 The power density is lower than that of the PEIS-6 composite material, which has a faster discharge rate of 29 ns and a power density of 30.2 MW / cm. 3 The higher power density. As shown in Figure b, the performance of the PEIS-6 composite material is almost unaffected after 10,000 cycles, while pure PEIS is broken down after 3,546 cycles, indicating that the bamboo-structured PEIS-6 composite material has excellent working stability at high temperatures.

[0086] Figure 6 The breakdown field strengths of pure PEIS, BN-PEIS, NBIT-PEIS, and PEIS-6 prepared in Example 1 at 150 °C or 200 °C are shown in the figure. As can be seen from the figure, at 150 °C, the breakdown field strength of pure PEIS is 4472 kV / cm, while it increases to 5087 kV / cm, 5483 kV / cm, and 6086 kV / cm in the BN-PEIS-based composite monolayer, NBIT-PEIS-based composite monolayer, and PEIS-6 composite, respectively. Similarly, at 200 °C, the breakdown field strength of pure PEIS is 3787 kV / cm, while it increases to 4479 kV / cm, 4967 kV / cm, and 5485 kV / cm in the BN-PEIS-based composite monolayer, NBIT-PEIS-based composite monolayer, and PEIS-6 composite, respectively.

[0087] Figure 7 The figures show the relative permittivity of pure PEIS, BN-PEIS, NBIT-PEIS, and PEIS-6 prepared in Example 1 at 150 °C or 200 °C. As can be seen from the figures, at 150 °C, the relative permittivity of pure PEIS is 3.3, while it increases to 3.5, 4.0, and 3.8 in the BN-PEIS-based composite monolayer, NBIT-PEIS-based composite monolayer, and PEIS-6 composite, respectively. Similarly, at 200 °C, the relative permittivity of pure PEIS is 3.1, while it increases to 3.5, 3.8, and 3.7 in the BN-PEIS-based composite monolayer, NBIT-PEIS-based composite monolayer, and PEIS-6 composite, respectively.

[0088] Figure 8The figures show the thermal conductivity of pure PEIS, BN-PEIS, NBIT-PEIS, and PEIS-6 prepared in Example 1 at 150 °C or 200 °C. As can be seen from the figures, the thermal conductivity of pure PEIS at 150 °C is 0.14 W / m². -1 K -1 In BN-PEIS-based composite single films, NBIT-PEIS-based composite single films, and PEIS-6 composites, the efficiency was increased to 0.27 W / m². -1 K -1 0.17 W m -1 K -1 and 0.22 W m -1 K -1 Similarly, at 200 °C, the thermal conductivity of pure PEIS is 0.15 W / m. -1 K -1 In BN-PEIS-based composite single films, NBIT-PEIS-based composite single films, and PEIS-6 composites, the W / m² was increased to 0.26 W / m², respectively. -1 K -1 0.18 W m -1 K -1 and 0.22 W m -1 K -1 .

[0089] Figure 9 The image shows the hysteresis loop of PEIS-6 prepared in Example 1 from room temperature to high temperature. According to the energy storage density calculation formula, the energy storage density of the PEIS-6 composite material at room temperature (25 °C) is 17.5 J / cm³. 3 As temperature increases, the energy storage density gradually decreases, with the energy storage densities at 75 ℃, 150 ℃, and 200 ℃ being 13.8 J / cm³. 3 9.6 J / cm 3 and 7.3 J / cm 3 .

Claims

1. A high temperature high performance dielectric composite material of multilayer structure embedded with sheet-like microcrystals and nanocrystals, respectively, characterized in that It is a multilayer structure polymer-based composite material composed of NBIT-PEIS-based composite material films and BN-PEIS-based composite material films alternately; The NBIT-PEIS-based composite material film is prepared from polyetherimide-co-poly sulfone polymer PEIS and two-dimensional filler NBIT microparticles, wherein the two-dimensional filler NBIT microparticles are oriented and arranged in the film, and the sheet normal direction is consistent with the thickness direction of the film; the BN-PEIS-based composite material film is prepared from polyetherimide-co-poly sulfone polymer PEIS and boron nitride BN nanosheets; The two-dimensional filler NBIT microparticle is Na 0.5 Bi 4.5 Ti4O 15 microparticle, and the diameter of the two-dimensional filler NBIT microparticle is 1 µm~2 µm, and the ratio of diameter to thickness is ≥5; The BN nanosheet has a sheet diameter of 50 nm to 500 nm, and a diameter-thickness ratio of ≥10. The mass percentage of the two-dimensional filler NBIT microparticles in the NBIT-PEIS-based composite material film is 0.15% to 0.95%; and the mass percentage of the boron nitride BN nanosheet in the BN-PEIS-based composite material film is 0.15% to 0.95%. The multi-layer structure high-temperature high-performance dielectric composite material embedded with the flaky microcrystal and nanocrystal respectively has effective energy storage density ≥8.9 J / cm 3 under the condition of temperature 200 ℃ and energy storage efficiency η>90 %, effective energy storage density ≥6.7 J / cm 3 .

2. The high temperature high performance dielectric composite material with multilayer structure embedded with flaky microcrystal and nanocrystal respectively according to claim 1, characterized in that The multilayer structure high-temperature high-performance dielectric composite material respectively embedded with sheet-shaped microparticles and nanocrystals is a 2-layer or more structure polymer-based composite material composed of NBIT-PEIS-based composite material films with a thickness of 1 μm to 5 μm and BN-PEIS-based composite material films with a thickness of 1 μm to 5 μm alternately; the two-dimensional filler NBIT microparticles have a sheet diameter of 1.1 µm to 1.9 µm; and the boron nitride BN nanosheet has a sheet diameter of 100 nm to 200 nm.

3. The high temperature high performance dielectric composite material with multilayer structure embedded with flaky microcrystal and nanocrystal respectively according to claim 1, characterized in that The total thickness of the multi-layer structure high-temperature high-performance dielectric composite material embedded with sheet-shaped microcrystals and nanocrystals respectively is 6-15 microns; the multi-layer structure high-temperature high-performance dielectric composite material embedded with sheet-shaped microcrystals and nanocrystals respectively has a charge and discharge rate of ≤30 ns, a power density of ≥25.0 MW / cm under the condition of a temperature of 200 DEG C and an electric field of 2000 kV / cm, and no energy storage performance attenuation after long-term cycling for 10000 times. 3 ​ 4. The method of claim 1, wherein the method of preparing a multi-layered structure high temperature high performance dielectric composite material embedded with microcrystal and nanocrystal flakes, respectively, is characterized by It is carried out in the following steps: Step one: preparation of two-dimensional filler NBIT microparticles: According to the chemical formula is Na 0.5 Bi 4.5 Ti4O 15 The stoichiometric ratio of the raw materials is taken, the mass ratio of the raw materials to the molten salt is 1:(1-20), and the two-dimensional filler NBIT microparticle is prepared by the molten salt growth method. Step two: preparation of a multilayer structure polymer-based composite material: NBIT-PEIS suspension and BN-PEIS suspension are respectively prepared from two-dimensional filler NBIT microparticles, boron nitride BN nanosheets, polyetherimide-co-poly sulfone polymer PEIS, and a solvent; the NBIT-PEIS suspension is cast on a substrate and vacuum dried to obtain an NBIT-PEIS-based composite material film, then the BN-PEIS suspension is cast on the NBIT-PEIS-based composite material film and vacuum dried to obtain a BN-PEIS-based composite material film, and then the above steps are repeated alternately, and finally the multilayer structure high-temperature high-performance dielectric composite material respectively embedded with sheet-shaped microparticles and nanocrystals is obtained by removing the substrate.

5. The method for preparing a multilayer structure high-temperature high-performance dielectric composite material embedded with sheet-shaped microcrystals and nanocrystals respectively according to claim 4, characterized in that The raw materials in step one are Na2CO3, Bi2O3, and TiO2; the molten salt in step one is NaCl; and the purity of the raw materials and the molten salt in step one is all ≥99.0%.

6. The method for preparing a multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky microcrystals and nanocrystals respectively according to claim 4, characterized in that The two-dimensional filler NBIT microparticle prepared by the molten salt growth method in step one is prepared by the following steps: taking ethanol or water as the ball milling medium, taking zirconium balls or agate balls as the milling balls, under the conditions of a rotation speed of 200 r / min to 400 r / min and a ball-to-material mass ratio of 1:(0.1 to 0.5), the raw material is mixed with the molten salt by ball milling for 25 h to 48 h to obtain a mixture, the mixture is calcined at a temperature of 810 ℃ to 1000 ℃ for 1.2 h to 4 h, and finally washed and dried to obtain the two-dimensional filler NBIT microparticle; the diameter of the milling ball is 1 mm to 10 mm.

7. The method for preparing a multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky microcrystals and nanocrystals respectively according to claim 4, characterized in that The NBIT-PEIS suspension liquid in step two is prepared by the following steps: The polyetherimide-co-poly sulfone polymer PEIS solid particles are added into N-methyl pyrrolidone, and stirred and dissolved at a stirring speed of 500 r / min to 900 r / min to obtain a PEIS solution; the two-dimensional filler NBIT microparticle is added into N-methyl pyrrolidone under the condition of a power of 100 W to 480 W, and ultrasonically treated for 30 min to 60 min to obtain an NBIT solution; the PEIS solution and the NBIT solution are mixed at a stirring speed of 500 r / min to 900 r / min for 24 h to 48 h to obtain the NBIT-PEIS suspension liquid.

8. The method for preparing a multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky microcrystals and nanocrystals respectively according to claim 4, characterized in that The BN-PEIS suspension liquid in step two is prepared by the following steps: The polyetherimide-co-poly sulfone polymer PEIS solid particles are added into N-methyl pyrrolidone, and stirred and dissolved at a stirring speed of 500 r / min to 900 r / min to obtain a PEIS solution; the boron nitride BN nanosheet is added into N-methyl pyrrolidone under the condition of a power of 100 W to 480 W, and ultrasonically treated for 30 min to 60 min to obtain a BN solution; The PEIS solution and the BN solution are mixed at a stirring speed of 500 r / min to 900 r / min for 24 h to 48 h to obtain the BN-PEIS suspension liquid.

9. The method for preparing a multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky microcrystals and nanocrystals respectively according to claim 4, characterized in that The total concentration of the polyetherimide-co-poly sulfone polymer PEIS and the two-dimensional filler NBIT microparticle in the NBIT-PEIS suspension liquid in step two is 0.12 g / mL to 0.18 g / mL; the total concentration of the polyetherimide-co-poly sulfone polymer PEIS and the boron nitride BN nanosheet in the BN-PEIS suspension liquid in step two is 0.12 g / mL to 0.18 g / mL.

10. The method for preparing a multi-layer structure high-temperature high-performance dielectric composite material embedded with flaky microcrystals and nanocrystals respectively according to claim 4, characterized in that The substrate in step two is a pretreated glass substrate, and the pretreatment is performed by using a plasma cleaning machine to clean for 5-10 minutes in an air atmosphere and at a power of 10.2-29.6 W; the casting in step two is specifically performed by using a casting machine to cast at a casting speed of 0.1-1.0 cm / s; and the vacuum drying in step two is specifically performed by vacuum drying at a temperature of 50-120 ℃ for 2-12 hours.

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