CN116791277B - A high temperature-resistant composite dielectric and its preparation method and application - Google Patents

Abstract

The invention discloses a high-temperature-resistant composite dielectric medium, a preparation method and application thereof, and belongs to the technical field of dielectric capacitors. The invention fills the ITIC into the polyetherimide matrix with high breakdown and high energy storage efficiency to prepare the composite medium, wherein the synergistic effect of the ITIC with multiple concentrations solves the problem that the polyetherimide can cause charge injection and charge migration in the medium along with the injection of electrons into the electrode under high temperature and high field. The conduction loss and the heat loss of the polyetherimide are reduced, and the insulation performance and the energy storage efficiency of the polyetherimide are improved. On the basis, polyether sulfone is added, when PESU molecular chains are added into PEI, the distance between the molecular chains is increased, the steering loss generated by dipole steering is reduced, and the energy storage efficiency is improved; meanwhile, the increase of sulfonyl and molecular spacing in PESU brings a certain improvement to the dielectric constant; furthermore, the sulfonyl and hydrogen on PEI methyl can also form a hydrogen bond, so that the breakdown strength is improved to a certain extent.

Description

A high temperature-resistant composite dielectric and its preparation method and application

Technical field

The invention relates to a high temperature-resistant composite dielectric and its preparation method and application, and belongs to the technical field of dielectric capacitors.

Background technique

Due to their unique advantages of high power density, dielectric capacitors are widely used in fast charging and discharging fields such as high-power pulse power supplies, hybrid vehicles, and electromagnetic weapons. With the advancement of technology and the continuous improvement of device power, the working environment temperature of dielectric capacitors continues to increase. Rising, which puts higher requirements on the temperature resistance and insulation properties of dielectric materials. However, the current commercial energy storage dielectric material, biaxially oriented polypropylene, not only has a low energy storage density at room temperature (~2J/cm ³ ), but also has poor high temperature resistance. The conductivity loss increases sharply in high temperature environments, which seriously shortens its life. Working stability and lifespan. In addition, under high temperature and high electric field of all-organic media, the injection of charges at the electrode and the increase of charge migration in the medium will gradually increase the conduction loss and heat loss, seriously deteriorating the insulation performance and energy storage efficiency of the polymer dielectric. The maximum operating temperature of traditional commercial BOPP film capacitors is only 105°C, and the energy storage density at room temperature is only ~2J/cm ³ . Working environments that exceed the temperature tolerance of BOPP will cause the performance of film capacitors to deteriorate rapidly or even fail, seriously affecting the normal operation of the equipment. Secondary cooling systems are commonly used in business to ensure the normal operation of film capacitors, but this limits the miniaturization and lightweight of equipment and hinders the development of related industries. As there is an urgent need for film capacitors with high temperature resistance and high energy storage density in industrial production, it is very necessary to create an all-organic insulating medium that can solve the problems of poor temperature resistance and low energy storage efficiency of polymer dielectrics.

Contents of the invention

Aiming at the problems of poor temperature resistance and low energy storage efficiency of existing all-organic insulating media, the present invention provides a high temperature-resistant composite dielectric and its preparation method and application.

Technical solution of the present invention:

One of the purposes of the present invention is to provide a high temperature-resistant composite dielectric. The dielectric has a laminated structure. Each layer is composed of PEI and/or PESU as a base and doped with ITIC. The concentration of doped ITIC in the dielectric is from top to bottom. From high to low, and then from low to high; the thickness of the dielectric is 10 to 13 μm.

To further define, the dielectric contains 5 ITIC concentrations, which are 0.25wt%, 0.2wt%, 0.15wt%, 0.1wt% and 0.05wt%.

To further limit, when the dielectric contains 5 ITIC concentrations, the spinning sequence is 0.25wt% ITIC solution, 0.2wt% ITIC solution, 0.15wt% ITIC solution; 0.1wt% ITIC solution, 0.05wt% ITIC solution, 0.1wt% ITIC solution, 0.15wt% ITIC solution, 0.2wt% ITIC solution, 0.25wt% ITIC solution.

To further define, the dielectric contains 4 ITIC concentrations, which are 0.25wt%, 0.2wt%, 0.15wt% and 0.1wt%.

To further define, when the dielectric contains 4 ITIC concentrations, the spinning sequence is 0.25wt% ITIC solution, 0.2wt% ITIC solution, 0.15wt% ITIC solution, 0.1wt% ITIC solution, 0.15wt% ITIC solution, 0.2wt% ITIC solution, 0.25wt% ITIC solution.

Further defined, the dielectric contains three ITIC concentrations of 0.25 wt%, 0.2 wt%, and 0.15 wt%.

To further define, when the dielectric contains three ITIC concentrations, the spinning order is 0.25wt% ITIC solution, 0.2wt% ITIC solution, 0.15wt% ITIC solution, 0.2wt% ITIC solution, and 0.25wt% ITIC solution.

It is further limited that the mass ratio of PEI and PESU is 9:1, 8:2, 7:3 or 6:4.

A second object of the present invention is to provide a method for preparing the above-mentioned high temperature-resistant composite dielectric, which method includes the following steps:

(1) Prepare spinning precursor liquid; use PEI and/or PESU as the matrix, dope ITIC with different qualities to obtain spinning precursor liquid with different ITIC concentrations;

(2) The obtained spinning precursors with different ITIC concentrations are electrospun in sequence, and each spinning precursor is subjected to initial curing treatment after completion of spinning to obtain a synergistic PEI and/or PESU blend base with multiple concentrations of ITIC. wet film;

(3) The wet film obtained is subjected to drying, step heat treatment and quenching treatment in sequence to obtain a high temperature resistant composite dielectric.

To further limit, (1) is: uniformly disperse ITIC in N-methylpyrrolidone solution, add a certain amount of PEI particles and/or PESU particles, and configure spinning precursor liquids with different ITIC concentrations.

To further limit, the specific operation process of (1) is:

First, filter the N-methylpyrrolidone solution using molecular sieves, weigh the ITIC mass corresponding to different concentrations, add it to the filtered N-methylpyrrolidone solution, and use a double-layer beaker to protect the solution under 50-70W ultrasound. Ultrasonic dispersion treatment was carried out under high power for 1 hour, and stirring treatment was carried out at a rotation speed of 200 r/min for 1.5 hours. After stirring, the solution was filtered using 800 mesh qualitative filter paper;

Then, the PEI particles and/or PESU particles are dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles are added to the ITIC-doped solution and heated and stirred for 12 hours at 60°C and 200r/min. After the end, use 400 mesh qualitative filter paper to filter. After filtering, the solution is protected by a double-layer beaker and then ultrasonicated for 0.5h at an ultrasonic power of 50 to 70W. After ultrasonic, stir for 1h at 300r/min, let stand for 12h, and Place in a vacuum oven for 2 hours to remove bubbles.

To further limit, the specific operation process of (2) is:

Raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust; then raise the temperature to 40°C and keep it for 4 hours, lower the humidity to a relative air humidity of 10%; and finally perform electrospinning.

To further limit, the electrospinning parameters in (2) are: the advancement speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, and the applied voltage of the syringe needle gradually increases from 5KV as the concentration decreases. As high as 7KV, the receiving end voltage corresponds to -5~-7KV, the temperature is 20°C, the relative humidity is 10%, and the spinning time of each spinning precursor liquid is 15 minutes.

To further qualify, the spinning needle adopts the 23G model.

To further limit, the voltage applied to the syringe needle of the spinning precursor solution with different ITIC concentrations in (2) is different.

To further limit, the applied voltage of 0.25wt% ITIC solution is 5KV, the applied voltage of 0.2wt% ITIC solution is 5.5KV, the applied voltage of 0.15wt% ITIC solution is 6KV, the applied voltage of 0.1wt% ITIC solution is 6.5KV, and the applied voltage of 0.05wt% ITIC The applied voltage of the concentration solution is 7KV.

It is further limited that the initial curing process of each spinning precursor liquid after completion of spinning is: heating the spinning machine to 40°C for 10 minutes of curing, and ventilating for 10 minutes.

To further limit, the drying process in (3) is: first, dry at 60°C for 1 to 2 hours under normal pressure; then dry at 0.04MPa, 80°C for 4 hours, and let stand in a fume hood for 10 minutes; then dry at 0.06MPa, 120°C for 2 hours, in a fume hood Let it stand for 20 minutes; then dry at 0.08MPa and 150℃ for 2 hours, and let it stand in a fume hood for 30 minutes; then dry at 0.09MPa and 200℃ for 2h and let it stand in a fume hood for 40min; finally, dry at 0.1MPa and 200℃ for 2h and let it stand in a fume hood for 40min. .

Further qualification, (3) medium step heat treatment is: place the dried wet film between the heated iron plates of a flat vulcanizer to quickly raise the temperature to 250°C, then slowly lower the temperature to 200°C, keep it warm for 30 minutes, and then perform step Type heat treatment, the first stage is 2.5Mpa, 200℃, hot pressing for 20min; the second stage is 5Mpa, the temperature is raised 2℃, hot pressed for 20min; the third stage is 7.5Mpa, the temperature is raised 2℃, hot pressed for 15min; the fourth stage, 10Mpa , temperature rise 2℃, hot pressing for 15min; the fifth stage is 12.5Mpa, temperature rise 2℃, hot pressing for 10min; the sixth stage is 15Mpa, temperature rise 2℃, hot pressing for 10min.

It is further limited that the quenching treatment process in (3) is: after the step heat treatment is completed, it is cooled to 0~25°C through a cold water treatment device.

The third object of the present invention is to provide an application of the above-mentioned high temperature-resistant composite dielectric, specifically in the field of rapid charge and discharge.

It is further defined that it is specifically used in high-power pulse power supplies, hybrid vehicles and electromagnetic weapons.

Beneficial effects of the present invention:

(1) The present invention fills ITIC into a polyetherimide matrix with high breakdown and high energy storage efficiency to prepare a composite medium. The synergistic effect of multiple concentrations of ITIC solves the problem of polyetherimide in high temperature and high fields. Injecting electrons with the electrode will lead to charge injection and charge migration within the medium. It reduces the conduction loss and heat loss of polyetherimide and improves its insulation performance and energy storage efficiency. In addition, the present invention adds polyethersulfone (PESU) to the foundation. When PESU molecular chains are added to PEI, the distance between the molecular chains will increase, reducing the steering loss caused by dipole steering, and improving the energy storage efficiency; at the same time, PESU The increase in the sulfone group and the molecular spacing will also bring a certain improvement to the dielectric constant; in addition, the sulfone group and the hydrogen on the PEI methyl group can also form hydrogen bonds, which improves the breakdown strength to a certain extent.

(2) The present invention has the synergistic effect of multi-concentration ITIC. By balancing the breakdown strength and dielectric properties of multi-concentration ITIC, the multi-concentration synergistic composite medium can simultaneously enhance energy storage while increasing a certain breakdown strength. The density and charge-discharge efficiency allow the composite medium to maintain extremely high energy storage performance, solving the shortcomings of previous all-organic composite media such as large dielectric loss and low energy storage efficiency under high temperatures and high fields. At the same time, the present invention fills ITIC into the PEI/PESU blended composite dielectric matrix with high breakdown and high energy storage efficiency. The synergistic effect of multiple concentrations of ITIC solves the problem of the composite dielectric injecting electrons with the electrode under high temperature and high field. It will lead to an increase in charge injection and charge migration within the medium, reducing conduction losses and heat losses, and improving its insulation performance and energy storage efficiency.

(3) The present invention provides a new way for multi-concentration synergistic composite media based on polyetherimide polymers to greatly improve energy density and charge and discharge efficiency. The organic medium has an energy storage density of 3.13J/cm ³ and an energy storage efficiency of 86.6% at a high temperature of 200°C and an electric field of 420MV/m. It can be used to manufacture dielectric energy storage devices with excellent energy storage characteristics and has broad applications in the field of dielectric capacitors. prospect. The present invention provides a new way for the composite medium of multi-concentration ITIC based on PEI/PESU to improve energy density and charge and discharge efficiency. The all-organic medium prepared by the present invention with polyetherimide and polyethersulfone as the matrix has the highest storage capacity. The energy density is 3.60J/cm ³ and the energy storage efficiency is 88%. It can be used to manufacture dielectric energy storage devices with excellent energy storage characteristics and has broad application prospects in the field of dielectric capacitors.

Description of drawings

Figure 1 is a comparative XRD pattern of the composite electrolyte obtained in Examples 1 to 3 and Comparative Example 1;

Figure 2 is an SEM photograph of the composite electrolyte obtained in Examples 1 to 3 and Comparative Example 1;

Figure 3 is a graph showing the change in dielectric constant with frequency of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1;

Figure 4 is a Weibull distribution diagram of the breakdown field strength of the composite electrolyte obtained in Examples 1 to 3 and Comparative Example 1 at a high temperature of 200°C;

Figure 5 is a comparison chart of the energy storage characteristics of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1;

Figure 6 is a comparative XRD pattern of the composite electrolyte obtained in Example 4 and Comparative Examples 1 to 6;

Figure 7 is an SEM photograph of the cross section of the composite dielectric obtained in Example 4;

Figure 8 is an SEM photograph of the cross section of the composite dielectric obtained in Comparative Example 1 and Comparative Example 2;

Figure 9 is an SEM photograph of the cross section of the composite dielectric obtained in Comparative Example 3 and Comparative Example 4;

Figure 10 is an SEM photograph of the cross section of the composite dielectric obtained in Comparative Example 5 and Comparative Example 6;

Figure 11 is a graph showing the change in dielectric constant with frequency of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6;

Figure 12 is a Weibull distribution diagram of the breakdown field strength of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6;

Figure 13 is a comparison chart of the energy storage characteristics of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6.

Detailed ways

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention will be described in detail below in conjunction with the examples in the description.

Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Those skilled in the art can do so without departing from the connotation of the present invention. Similar generalizations are made, and therefore the present invention is not limited to the specific embodiments disclosed below.

Second, reference herein to "one embodiment" or "an embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. "In one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

The molecular formula of the PEI particles used in the following examples and comparative examples is C ₃₇ H ₂₈ N ₂ O ₈ , the relative density is 1.27g/ml, and the glass transition temperature is 217°C. The molecular formula of PESU particles is C ₁₈ H ₁₂ SO ₄ , the relative density is 1.37g/ml, and the glass transition temperature is 225°C.

Example 1

This example uses polyetherimide as the base, and is obtained by alternating 5 polyetherimides with different ITIC concentrations layer by layer and through hot pressing and quenching processes. The mass fraction change values of ITIC are all 0.05wt.%. , the specific ITIC volume content of each layer is:

PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.1wt.%ITIC, PEI-0.05wt.%ITIC, PEI-0.1wt.%ITIC, PEI- 0.15wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.25wt.%ITIC.

The process steps for preparing high temperature-resistant composite dielectric in this embodiment are as follows:

(1) Prepare spinning precursor liquid;

First, filter the N-methylpyrrolidone solution using molecular sieves, weigh the ITIC mass corresponding to different concentrations, add it to the filtered N-methylpyrrolidone solution, and protect the solution with a double-layer beaker under 60W ultrasonic power. Carry out ultrasonic dispersion treatment for 1 hour, and stirring treatment at a rotation speed of 200 r/min for 1.5 hours. After stirring, filter the solution using 800 mesh qualitative filter paper;

Then, the PEI particles were dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles were added to the ITIC-doped solution and heated and stirred for 12 hours at 60°C and 200r/min. After the stirring, 400 mesh was used. Filter with qualitative filter paper. After filtration, the solution is protected by a double-layer beaker and ultrasonicated at 60W ultrasonic power for 0.5h. After ultrasonicization, it is stirred at 300r/min for 1h, left to stand for 12h, and placed in a vacuum oven for 2h to remove bubbles. The ITIC mass fractions of the obtained spinning precursor liquid were 0.25wt.%ITIC, 0.2wt.%ITIC, 0.15wt.%ITIC, 0.1wt.%ITIC, and 0.05wt.%ITIC respectively.

(2) Electrospinning;

Inhale each volume fraction of the PEI-ITIC spinning precursor solution obtained in step 1 into the syringe respectively, according to PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.1wt. %ITIC, PEI-0.05wt.%ITIC, PEI-0.1wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.25wt.%ITIC are sequentially carried out in the order of low speed electrospinning , to obtain a wet film.

The electrospinning process is:

First, raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust;

Then, increase the temperature to 40°C and maintain it for 4 hours to reduce the humidity to a relative air humidity of 10%;

Finally, electrospinning is performed. The specific spinning process is:

The advancement speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, the spinning needle adopts 23G model, the voltage applied to the syringe needle gradually increases from 5KV to 7KV as the concentration decreases, and the receiving end The corresponding voltage is -5~-7KV, the spinning environment temperature is 20°C, and the relative air humidity is 10%. The applied voltage of 0.25wt% ITIC solution is 5KV, and the receiving terminal voltage is -5KV; the applied voltage of 0.2wt% ITIC solution is 5.5KV, and the receiving terminal voltage is -5.5KV; the applied voltage of 0.15wt% ITIC solution is 6KV, and the receiving terminal voltage is -6KV; the applied voltage of 0.1wt% ITIC solution is 6.5KV, and the receiving terminal voltage is -6.5KV; the applied voltage of 0.05wt% ITIC concentration solution is 7KV, and the receiving terminal voltage is -7KV. Each layer of solution was spun for 12 minutes. After spinning one layer, the spinning machine was heated to 40°C for 10 minutes of solidification and ventilated for 10 minutes.

(3) Wet film post-processing;

The obtained wet film is dried, stepped heat treated and quenched in sequence to obtain a high temperature resistant composite dielectric. The specific process is as follows:

<1> First heat the spun film at 60°C for 1 hour on a heating table in a fume hood, and then place it in a vacuum oven to dry for 4 hours under vacuum conditions of 0.04MPa and 80°C. After taking it out, let it stand in the fume hood for 10 minutes; vacuum Dry at 0.06MPa and 120°C for 2 hours, then take it out and let it stand in a fume hood for 20 minutes; dry it under vacuum at 0.08MPa and 150°C for 2 hours, take it out and let it stand in a fume hood for 30 minutes; under vacuum condition at 0.09MPa and 200°C. Dry for 2 hours, take it out and let it stand in a fume hood for 40 minutes; finally dry it in an empty state at 0.1MPa and 200°C for 2 hours, take it out and let it stand in a ventilated and dry place for 40 minutes.

<2>Use a flat vulcanizing machine, place the heating iron plate in the flat vulcanizing machine and heat it to 300°C and keep it for 1 hour; after it drops to room temperature, spray alcohol and gradually raise the temperature to 300°C, keep it for 1 hour and then lower the temperature to room temperature. Place the film between heated iron plates and quickly raise the temperature to 250°C, then slowly lower the temperature to 200°C and keep it for 30 minutes. Then perform step heat treatment, in which the first stage is maintained at 2.5Mpa and 200°C for 20 minutes; the second stage is raised to 5Mpa, the temperature is raised to 2°C, and maintained for 20min; the third stage is maintained at 7.5Mpa, and the temperature is raised to 2°C for 15min; In the fourth stage, the pressure is increased to 10Mpa, and the temperature is increased by 2°C and maintained for 15 minutes; in the fifth stage, the pressure is increased to 12.5Mpa, and the temperature is increased by 2°C and maintained for 10 minutes; in the sixth stage, the pressure is increased to 15Mpa, and the temperature is increased by 2°C and maintained for 10 minutes.

<3>After the step heat treatment is completed, it is directly cooled to 0~25℃ by the cold water treatment device. A dense, synergistic composite dielectric of five concentrations with a thickness of about 10 μm was obtained.

Example 2

In this example, polyetherimide is used as the matrix, and four polyetherimides with different ITIC concentrations are obtained by alternating layer by layer and undergoing hot pressing and quenching processes. The mass fraction change values of ITIC are all 0.05wt.%. , the specific filler and ITIC volume contents in each filled phase are as follows:

PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.1wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.2wt.%ITIC, PEI- 0.25wt.%ITIC.

The process steps for preparing high temperature-resistant composite dielectric in this embodiment are as follows:

(1) Prepare spinning precursor liquid;

First, filter the N-methylpyrrolidone solution using molecular sieves, weigh the ITIC mass corresponding to different concentrations, add it to the filtered N-methylpyrrolidone solution, and protect the solution with a double-layer beaker under 60W ultrasonic power. Carry out ultrasonic dispersion treatment for 1 hour, and stirring treatment at a rotation speed of 200 r/min for 1.5 hours. After stirring, filter the solution using 800 mesh qualitative filter paper;

Then, the PEI particles were dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles were added to the ITIC-doped solution and heated and stirred for 12 hours at 60°C and 200r/min. After the stirring, 400 mesh was used. Filter with qualitative filter paper. After filtration, the solution is protected by a double-layer beaker and ultrasonicated at 60W ultrasonic power for 0.5h. After ultrasonicization, it is stirred at 300r/min for 1h, left to stand for 12h, and placed in a vacuum oven for 2h to remove bubbles. The ITIC mass fractions of the obtained spinning precursor liquid were 0.25wt.%ITIC, 0.2wt.%ITIC, 0.15wt.%ITIC, and 0.1wt.%ITIC respectively.

(2) Electrospinning;

Inhale each volume fraction of the PEI-ITIC spinning precursor solution obtained in step 1 into the syringe respectively, according to PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.1wt. %ITIC, PEI-0.15wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.25wt.%ITIC were electrospun at low speed in order to obtain a wet film.

The electrospinning process is:

First, raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust;

Then, increase the temperature to 40°C and maintain it for 4 hours to reduce the humidity to a relative air humidity of 10%;

Finally, electrospinning is performed. The specific spinning process is:

The advancement speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, the spinning needle adopts 23G model, the voltage applied to the syringe needle gradually increases from 5KV to 7KV as the concentration decreases, and the receiving end The corresponding voltage is -5~-7KV, the spinning environment temperature is 20°C, and the relative air humidity is 10%. The applied voltage of 0.25wt% ITIC solution is 5KV, and the receiving terminal voltage is -5KV; the applied voltage of 0.2wt% ITIC solution is 5.5KV, and the receiving terminal voltage is -5.5KV; the applied voltage of 0.15wt% ITIC solution is 6KV, and the receiving terminal voltage is -6KV; the applied voltage of 0.1wt% ITIC solution is 6.5KV, and the receiving terminal voltage is -6.5KV. Each layer of solution was spun for 17 minutes. After spinning one layer, the spinning machine was heated to 40°C for 10 minutes of solidification and ventilated for 10 minutes.

(3) Wet film post-processing;

The obtained wet film is dried, stepped heat treated and quenched in sequence to obtain a high temperature resistant composite dielectric. The specific process is as follows:

<1> First heat the spun film at 60°C for 1 hour on a heating table in a fume hood, and then place it in a vacuum oven to dry for 4 hours under vacuum conditions of 0.04MPa and 80°C. After taking it out, let it stand in the fume hood for 10 minutes; vacuum Dry at 0.06MPa and 120°C for 2 hours, then take it out and let it stand in a fume hood for 20 minutes; dry it under vacuum at 0.08MPa and 150°C for 2 hours, take it out and let it stand in a fume hood for 30 minutes; under vacuum condition at 0.09MPa and 200°C. Dry for 2 hours, take it out and let it stand in a fume hood for 40 minutes; finally dry it in an empty state at 0.1MPa and 200°C for 2 hours, take it out and let it stand in a ventilated and dry place for 40 minutes.

<2>Use a flat vulcanizing machine, place the heating iron plate in the flat vulcanizing machine and heat it to 300°C and keep it for 1 hour; after it drops to room temperature, spray alcohol and gradually raise the temperature to 300°C, keep it for 1 hour and then lower the temperature to room temperature. Place the film between heated iron plates and quickly raise the temperature to 250°C, then slowly lower the temperature to 205°C and keep it for 30 minutes. Then perform step heat treatment, in which the first stage is maintained at 2.5Mpa and 205°C for 20 minutes; the second stage is raised to 5Mpa, the temperature is raised to 2°C, and maintained for 20 minutes; the third stage is maintained at 7.5Mpa, and the temperature is raised to 2°C for 15 minutes; In the fourth stage, the pressure is increased to 10Mpa, and the temperature is increased by 2°C and maintained for 15 minutes; in the fifth stage, the pressure is increased to 12.5Mpa, and the temperature is increased by 2°C and maintained for 10 minutes; in the sixth stage, the pressure is increased to 15Mpa, and the temperature is increased by 2°C and maintained for 10 minutes.

<3>After the step heat treatment is completed, it is directly cooled to 0~25℃ by the cold water treatment device. A dense composite dielectric with synergy of four concentrations was obtained with a thickness of about 10 μm.

Example 3

This example uses polyetherimide as the matrix, and is obtained by alternating three polyetherimides with different ITIC concentrations layer by layer and through hot pressing and quenching processes. The mass fraction change values of ITIC are all 0.05wt.%. , the specific filler and ITIC volume contents in each filled phase are as follows:

PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.25wt.%ITIC.

The process steps for preparing high temperature-resistant composite dielectric in this embodiment are as follows:

(1) Prepare spinning precursor liquid;

First, filter the N-methylpyrrolidone solution using molecular sieves, weigh the ITIC mass corresponding to different concentrations, add it to the filtered N-methylpyrrolidone solution, and protect the solution with a double-layer beaker under 60W ultrasonic power. Carry out ultrasonic dispersion treatment for 1 hour, and stirring treatment at a rotation speed of 200 r/min for 1.5 hours. After stirring, filter the solution using 800 mesh qualitative filter paper;

Then, the PEI particles were dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles were added to the ITIC-doped solution and heated and stirred for 12 hours at 60°C and 200r/min. After the stirring, 400 mesh was used. Filter with qualitative filter paper. After filtration, the solution is protected by a double-layer beaker and ultrasonicated at 60W ultrasonic power for 0.5h. After ultrasonicization, it is stirred at 300r/min for 1h, left to stand for 12h, and placed in a vacuum oven for 2h to remove bubbles. The ITIC mass fractions of the obtained spinning precursor liquid were 0.25wt.%ITIC, 0.2wt.%ITIC, and 0.15wt.%ITIC respectively.

(2) Electrospinning;

Inhale each volume fraction of the PEI-ITIC spinning precursor solution obtained in step 1 into the syringe respectively, according to PEI-0.25wt.%ITIC, PEI-0.2wt.%ITIC, PEI-0.15wt.%ITIC, PEI-0.2wt. %ITIC, PEI-0.25wt.%ITIC were electrospun in sequence to obtain a wet film.

The electrospinning process is:

First, raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust;

Then, increase the temperature to 40°C and maintain it for 4 hours to reduce the humidity to a relative air humidity of 10%;

Finally, electrospinning is performed. The specific spinning process is:

The advancement speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, the spinning needle adopts 23G model, the voltage applied to the syringe needle gradually increases from 5KV to 7KV as the concentration decreases, and the receiving end The corresponding voltage is -5~-7KV, the spinning environment temperature is 20°C, and the relative air humidity is 10%. The applied voltage of 0.25wt% ITIC solution is 5KV, and the receiving terminal voltage is -5KV; the applied voltage of 0.2wt% ITIC solution is 5.5KV, and the receiving terminal voltage is -5.5KV; the applied voltage of 0.15wt% ITIC solution is 6KV, and the receiving terminal voltage is -6KV. Each layer of solution was spun for 24 minutes. After spinning one layer, the spinning machine was heated to 40°C for 10 minutes of solidification and ventilated for 10 minutes.

(3) Wet film post-processing;

The obtained wet film is dried, stepped heat treated and quenched in sequence to obtain a high temperature resistant composite dielectric. The specific process is as follows:

<1> First heat the spun film at 60°C for 1 hour on a heating table in a fume hood, and then place it in a vacuum oven to dry for 4 hours under vacuum conditions of 0.04MPa and 80°C. After taking it out, let it stand in the fume hood for 10 minutes; vacuum Dry at 0.06MPa and 120°C for 2 hours, then take it out and let it stand in a fume hood for 20 minutes; dry it under vacuum at 0.08MPa and 150°C for 2 hours, take it out and let it stand in a fume hood for 30 minutes; under vacuum condition at 0.09MPa and 200°C. Dry for 2 hours, take it out and let it stand in a fume hood for 40 minutes; finally dry it in an empty state at 0.1MPa and 200°C for 2 hours, take it out and let it stand in a ventilated and dry place for 40 minutes.

<2>Use a flat vulcanizing machine, place the heating iron plate in the flat vulcanizing machine and heat it to 300°C and keep it for 1 hour; after it drops to room temperature, spray alcohol and gradually raise the temperature to 300°C, keep it for 1 hour and then lower the temperature to room temperature. Place the film between heated iron plates and quickly raise the temperature to 250°C, then slowly lower the temperature to 210°C and keep it for 30 minutes. Then perform step heat treatment, in which the first stage is maintained at 2.5Mpa and 210°C for 20 minutes; the second stage is raised to 5Mpa, the temperature is raised to 2°C, and maintained for 20 minutes; the third stage is maintained at 7.5Mpa, and the temperature is raised to 2°C for 15 minutes; In the fourth stage, the pressure is increased to 10Mpa, and the temperature is increased by 2°C and maintained for 15 minutes; in the fifth stage, the pressure is increased to 12.5Mpa, and the temperature is increased by 2°C and maintained for 10 minutes; in the sixth stage, the pressure is increased to 15Mpa, and the temperature is increased by 2°C and maintained for 10 minutes.

<3>After the step heat treatment is completed, it is directly cooled to 0~25℃ by the cold water treatment device. A dense composite dielectric with three synergistic concentrations with a thickness of about 10 μm was obtained.

Comparative example 1

This comparative example provides the preparation of a pure polyetherimide medium. The specific method steps are as follows:

(1) Prepare spinning precursor liquid;

First, filter the N-methylpyrrolidone solution using molecular sieves;

Then, the PEI particles were dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles were added to the N-methylpyrrolidone solution and heated and stirred for 12 hours at 60°C and 200r/min. After the stirring, 400 The purpose is to filter with qualitative filter paper. After filtration, the solution is protected by a double-layer beaker and then ultrasonicated for 0.5h under 60W ultrasonic power. After ultrasonic, stir for 1h at 300r/min, leave to stand for 12h, and place in a vacuum oven for 2h to remove bubbles. . The obtained spinning precursor liquid.

(2) Electrospinning;

Inhale the spinning precursor liquid obtained in step 1 into a syringe, perform low-speed electrospinning, and obtain a wet film.

The electrospinning process is:

First, raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust;

Then, increase the temperature to 40°C and maintain it for 4 hours to reduce the humidity to a relative air humidity of 10%;

Finally, electrospinning is performed. The specific spinning process is:

The advancing speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, the spinning needle adopts 23G model, the voltage applied to the syringe needle is 6.5KV, and the corresponding receiving end voltage is -6.5KV, spinning The ambient temperature is 20°C and the relative air humidity is 10%. Spinning for 120 minutes, after completion, the spinning machine was heated to 40°C for 10 minutes of solidification and ventilated for 10 minutes.

(3) Wet film post-processing;

The obtained wet film is dried, stepped heat treated and quenched in sequence to obtain a high temperature resistant composite dielectric. The specific process is as follows:

<1> First heat the spun film at 60°C for 1 hour on a heating table in a fume hood, and then place it in a vacuum oven to dry for 4 hours under vacuum conditions of 0.04MPa and 80°C. After taking it out, let it stand in the fume hood for 10 minutes; vacuum Dry at 0.06MPa and 120°C for 2 hours, then take it out and let it stand in a fume hood for 20 minutes; dry it under vacuum at 0.08MPa and 150°C for 2 hours, take it out and let it stand in a fume hood for 30 minutes; under vacuum condition at 0.09MPa and 200°C. Dry for 2 hours, take it out and let it stand in a fume hood for 40 minutes; finally dry it in an empty state at 0.1MPa and 200°C for 2 hours, take it out and let it stand in a ventilated and dry place for 40 minutes.

<2>Use a flat vulcanizing machine, place the heating iron plate in the flat vulcanizing machine and heat it to 300°C and keep it for 1 hour; after it drops to room temperature, spray alcohol and gradually raise the temperature to 300°C, keep it for 1 hour and then lower the temperature to room temperature. Place the film between heated iron plates and quickly raise the temperature to 250°C, then slowly lower the temperature to 205°C and keep it for 30 minutes. Then perform step heat treatment, in which the first stage is maintained at 2.5Mpa and 205°C for 20 minutes; the second stage is raised to 5Mpa, the temperature is raised to 2°C, and maintained for 20 minutes; the third stage is maintained at 7.5Mpa, and the temperature is raised to 2°C for 15 minutes; In the fourth stage, the pressure is increased to 10Mpa, and the temperature is increased by 2°C and maintained for 15 minutes; in the fifth stage, the pressure is increased to 12.5Mpa, and the temperature is increased by 2°C and maintained for 10 minutes; in the sixth stage, the pressure is increased to 15Mpa, and the temperature is increased by 2°C and maintained for 10 minutes.

<3>After the step heat treatment is completed, it is directly cooled to 0~25℃ by the cold water treatment device. A dense polyetherimide full composite dielectric with a thickness of approximately 10 μm was obtained.

Effect example 1

The structure and performance of the four composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1 were characterized. The results are as follows:

(1) Figure 1 is the XRD comparison pattern of the composite electrolyte obtained in Examples 1 to 3 and Comparative Example 1. As can be seen from Figure 1, the multi-concentration synergistic composite medium provided in Examples 1 to 3 is compared with the PEI of Comparative Example 1. No new crystalline phase is formed, and doping multi-concentration ITIC has no effect on the structure of its composite medium.

(2) Figure 2 is a SEM photo of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1. It can be seen from Figure 2 that the scanning electron microscopy images of the four composite electrolytes all have a uniform texture, a dense and defect-free structure, and no phases appear. Separation, filling and accumulation phenomena indicate that ITIC is well compatible with PEI.

(3) Figure 3 is a graph showing the change in dielectric constant of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1 with frequency. From Figure 3, it can be seen that as the frequency changes, Examples 1 to 3 and Comparative Example 1 provide The dielectric constants and dielectric losses of the four composite electrolytes have good stability, and there is no major relaxation phenomenon with changes in frequency. At the same time, because ITIC is a polar small molecule, the dielectric constant of the composite medium is slightly improved after being added.

(4) Figure 4 is a Weibull distribution diagram of the breakdown field strength of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1 at a high temperature of 200°C. It can be seen from Figure 4 that the five ITIC concentrations obtained in Example 1 The breakdown field strength of the synergistic composite medium is higher than that of other insulating media. This is due to the high electron affinity of ITIC that attracts electrons and hinders electron migration in the medium, resulting in an increase in the breakdown field strength. Under high temperature and high field, the synergistic effect of multiple concentrations can reduce the intrinsic excited electrons of ITIC as a molecular semiconductor, reducing the mobile charges in the medium and further improving the breakdown strength.

(5) Figure 5 is a comparison chart of the energy storage characteristics of the composite electrolytes obtained in Examples 1 to 3 and Comparative Example 1. From Figure 5, it can be seen that the energy storage density and high energy storage density of the five ITIC concentration synergistic composite media prepared in Example 1 Compared with other composite media, under a high temperature of 200°C and an electric field of 420MV/m, an energy storage density of 3.13J/ ^cm3 and an efficiency of 86% can be obtained. This is due to the synergistic effect of multiple concentrations, which optimizes the polarization and breakdown performance between each concentration. At the same time, the intrinsic excited electrons of ITIC as a molecular semiconductor are reduced, which reduces the conduction loss and improves the efficiency.

Example 4

This example uses PEI/PESU blended composite media as the matrix, which is obtained by alternating electrospinning layer by layer of PEI/PESU blended composite media with 5 ITIC concentrations and hot pressing and quenching processes. The mass ratio of PEI to PESU is is 8:2, the volume fraction change value of ITIC is 0.05wt.%, the specific mass fraction of ITIC in each layer is:

PEI/PESU-0.25wt.%ITIC, PEI/PESU-0.2wt.%ITIC, PEI/PESU-0.15wt.%ITIC, PEI/PESU-0.1wt.%ITIC, PEI/PESU-0.05wt.%ITIC.

The process steps for preparing high temperature-resistant composite dielectric in this embodiment are as follows:

(1) Prepare spinning precursor liquid;

First, filter the N-methylpyrrolidone solution using molecular sieves, weigh the ITIC mass corresponding to different concentrations, add it to the filtered N-methylpyrrolidone solution, and protect the solution with a double-layer beaker under 60W ultrasonic power. Carry out ultrasonic dispersion treatment for 1 hour, and stirring treatment at a rotation speed of 200 r/min for 1.5 hours. After stirring, filter the solution using 800 mesh qualitative filter paper;

Then, the PEI particles and PESU particles were dried in an oven at 150°C for 4 hours to completely remove the moisture. The dried PEI particles and PESU particles (the mass ratio of PEI and PESU was 8:2) were added to the solution doped with ITIC at 60 Heat and stir for 12 hours under the conditions of ℃ and 200r/min. After stirring, filter it using 400 mesh qualitative filter paper. After filtering, the solution is protected by a double-layer beaker and then ultrasonicated at 60W ultrasonic power for 0.5h. After ultrasonic treatment, it is processed at 300r/min. Stir for 1 hour, let stand for 12 hours, and place in a vacuum oven for 2 hours to remove bubbles. The ITIC mass fractions of the obtained spinning precursor liquid were 0.25wt.%ITIC, 0.2wt.%ITIC, 0.15wt.%ITIC, 0.1wt.%ITIC, and 0.05wt.%ITIC respectively.

(2) Electrospinning;

Inhale each volume fraction of the PEI/PESU-ITIC spinning precursor solution obtained in step 1 into the syringe respectively, according to PEI/PESU-0.25wt.%ITIC, PEI/PESU-0.2wt.%ITIC, PEI/PESU-0.15wt. %ITIC, PEI/PESU-0.1wt.%ITIC, PEI/PESU-0.05wt.%ITIC, PEI/PESU-0.1wt.%ITIC, PEI/PESU-0.15wt.%ITIC, PEI/PESU-0.2wt. %ITIC, PEI/PESU-0.25wt.%ITIC were electrospun in sequence to obtain a wet film.

The electrospinning process is:

First, raise the relative humidity of the air in the electrospinning machine to 60% and keep it for 4 hours to remove floating dust;

Then, increase the temperature to 40°C and maintain it for 4 hours to reduce the humidity to a relative air humidity of 10%;

Finally, electrospinning is performed. The specific spinning process is:

The advancement speed of the syringe is 0.15mm/min, the receiver speed is 200r/min, the receiving distance is 15cm, the spinning needle adopts 23G model, the voltage applied to the syringe needle gradually increases from 5KV to 7KV as the concentration decreases, and the receiving end The corresponding voltage is -5~-7KV, the spinning environment temperature is 20°C, and the relative air humidity is 10%. The applied voltage of 0.25wt% ITIC solution is 5KV, and the receiving terminal voltage is -5KV; the applied voltage of 0.2wt% ITIC solution is 5.5KV, and the receiving terminal voltage is -5.5KV; the applied voltage of 0.15wt% ITIC solution is 6KV, and the receiving terminal voltage is -6KV; the applied voltage of 0.1wt% ITIC solution is 6.5KV, and the receiving terminal voltage is -6.5KV; the applied voltage of 0.05wt% ITIC concentration solution is 7KV, and the receiving terminal voltage is -7KV. Each layer of solution was spun for 15 minutes. After spinning one layer, the spinning machine was heated to 40°C to solidify for 10 minutes and ventilated for 10 minutes.

(3) Wet film post-processing;

The obtained wet film is dried, stepped heat treated and quenched in sequence to obtain a high temperature resistant composite dielectric. The specific process is as follows:

<1> First heat the spun film at 60°C for 1 hour on a heating table in a fume hood, and then place it in a vacuum oven to dry for 4 hours under vacuum conditions of 0.04MPa and 80°C. After taking it out, let it stand in the fume hood for 10 minutes; vacuum Dry at 0.06MPa and 120°C for 2 hours, then take it out and let it stand in a fume hood for 20 minutes; dry it under vacuum at 0.08MPa and 150°C for 2 hours, take it out and let it stand in a fume hood for 30 minutes; under vacuum condition at 0.09MPa and 200°C. Dry for 2 hours, take it out and let it stand in a fume hood for 40 minutes; finally dry it in an empty state at 0.1MPa and 200°C for 2 hours, take it out and let it stand in a ventilated and dry place for 40 minutes.

<2>Use a flat vulcanizing machine, place the heating iron plate in the flat vulcanizing machine and heat it to 300°C and keep it for 1 hour; after it drops to room temperature, spray alcohol and gradually raise the temperature to 300°C, keep it for 1 hour and then lower the temperature to room temperature. Place the film between heated iron plates and quickly raise the temperature to 250°C, then slowly lower the temperature to 200°C and keep it for 30 minutes. Then perform step heat treatment, in which the first stage is maintained at 2.5Mpa and 200°C for 20 minutes; the second stage is raised to 5Mpa, the temperature is raised to 2°C, and maintained for 20min; the third stage is maintained at 7.5Mpa, and the temperature is raised to 2°C for 15min; In the fourth stage, the pressure is increased to 10Mpa, and the temperature is increased by 2°C and maintained for 15 minutes; in the fifth stage, the pressure is increased to 12.5Mpa, and the temperature is increased by 2°C and maintained for 10 minutes; in the sixth stage, the pressure is increased to 15Mpa, and the temperature is increased by 2°C and maintained for 10 minutes.

<3>After the step heat treatment is completed, it is directly cooled to 0~25℃ by the cold water treatment device. A dense composite dielectric with synergy of five concentrations (referred to as 20% PESU-9 layer) with a thickness of about 10 μm was obtained.

Comparative example 2

This comparative example provides the preparation of a pure polyethersulfone medium. The specific preparation differs from Comparative Example 1 in that polyethersulfone is used instead of polyetherimide. The remaining operating procedures and parameter settings are the same as Comparative Example 1. A dense polyethersulfone composite dielectric with a thickness of about 10 μm was obtained.

Comparative example 3

This comparative example provides a preparation of PEI and PESU blend composite media. The specific preparation differs from Comparative Example 1 in that: a blend of PEI and PESU with a mass of 9:1 is used to replace polyetherimide, and the remaining operations are The process and parameter settings were the same as those in Comparative Example 1, and a dense PEI/PESU (9:1) blend composite medium with a thickness of about 10 μm was obtained.

Comparative example 4

This comparative example provides a preparation of PEI and PESU blend composite media. The specific preparation differs from Comparative Example 1 in that: a blend of PEI and PESU with a mass of 8:2 is used to replace polyetherimide, and the remaining operations The process and parameter settings were the same as those in Comparative Example 1, and a dense PEI/PESU (8:2) blend composite medium with a thickness of about 10 μm was obtained.

Comparative example 5

This comparative example provides a preparation of PEI and PESU blend composite media. The specific preparation differs from Comparative Example 1 in that: a blend of PEI and PESU with a mass of 7:3 is used to replace polyetherimide, and the remaining operations are The process and parameter settings were the same as those in Comparative Example 1, and a dense PEI/PESU (7:3) blend composite medium with a thickness of about 10 μm was obtained.

Comparative example 6

This comparative example provides a preparation of PEI and PESU blend composite media. The specific preparation differs from Comparative Example 1 in that: a blend of PEI and PESU with a mass of 6:4 is used to replace polyetherimide, and the remaining operations are The process and parameter settings were the same as those in Comparative Example 1, and a dense PEI/PESU (6:4) blend composite medium with a thickness of about 10 μm was obtained.

Effect example 2

The structure and performance of the four composite dielectrics obtained in Example 4 and Comparative Examples 1 to 6 were characterized. The results are as follows:

Figure 6 is a comparative XRD pattern of the composite electrolyte obtained in Example 4 and Comparative Examples 1 to 6. It can be seen from Figure 6 that pure PESU has a higher peak near a low angle than pure PEI. Therefore, as the PESU content increases, the peak value of the PESU/PEI composite medium near the angle value of 20 gradually increases, proving that PESU is successfully introduced.

Figures 7 to 10 are SEM photos of the cross-sections of the composite dielectrics obtained in Example 4 and Comparative Examples 1 to 6 respectively. It can be seen from the figures that the dielectrics with various doping ratios have uniform, dense and defect-free structures. There are obvious phenomena such as phase separation and filling phase accumulation. It shows that PEI, PESU and ITIC have good compatibility.

Figure 11 is a graph of the change in dielectric constant with frequency of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6. It can be seen from Figure 11 that compared to PEI, the relative dielectric constant and dielectric loss of PESU are relatively high. As the content of PESU introduced into PEI gradually increases, the dielectric constant and dielectric loss of PEI/PESU increase. When PEI:PESU=6:4, the dielectric constant is the largest. This is because the distance between molecular chains increases and dipole steering polarization is more likely to occur. For the seven media provided in Example 4 and Comparative Examples 1, 2, 3, 4, 5, and 6, the dielectric loss remains at a low value.

Figure 12 is a Weibull distribution diagram of the breakdown field strength of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6. It can be seen from Figure 12 that as the PESU content increases, the breakdown strength first increases and then decreases. In PEI: PESU=8:2 is the maximum breakdown strength. Based on the composite medium of PEI:PESU=8:2, the breakdown strength is further improved by the synergistic effect of five concentrations of ITIC, reaching 480kv/mm.

Figure 13 is a comparison chart of the energy storage characteristics of the composite dielectric obtained in Example 4 and Comparative Examples 1 to 6. It can be seen from Figure 13 that Example 4 has a synergistic effect on the basis of the PEI:PESU=8:2 composite medium. The energy storage density is higher than other composite media. At a high temperature of 200°C and an electric field strength of 440MV/m, an energy storage density of 3.6J/ ^cm3 and an efficiency of 88% can be obtained.

Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (7)

1. A preparation method of a high temperature resistant composite dielectric medium is characterized in that the dielectric medium is of a laminated structure, each layer is formed by taking PEI and/or PESU as a matrix and doping ITIC, and the concentration of the dielectric medium doping ITIC is sequentially from top to bottom and then from bottom to top; the thickness of the dielectric is 10-13 mu m;

the preparation method of the high temperature resistant composite dielectric medium comprises the following steps:

(1) Preparing spinning precursor liquid; taking PEI and/or PESU as a matrix, doping ITIC with different mass to obtain spinning precursor solutions with different ITIC concentrations;

(2) Sequentially carrying out electrostatic spinning on the obtained spinning precursor solutions with different ITIC concentrations, and carrying out primary curing treatment on each spinning precursor solution after spinning is completed to obtain a multi-concentration ITIC synergistic PEI and/or PESU blending base wet film;

the electrostatic spinning parameters in the step (2) are as follows: the advancing speed of the injector is 0.15mm/min, the speed of the receiver is 200r/min, the receiving distance is 15cm, the voltage applied to the needle of the injector is 5-7 KV, the voltage of the receiving end is-5-7 KV, the temperature is 20 ℃, the relative humidity is 10%, and the spinning time of each spinning precursor solution is 15min;

(3) Sequentially performing drying, step-type heat treatment and quenching treatment on the obtained wet film to obtain a high-temperature-resistant composite dielectric;

the drying treatment in the step (3) is as follows: firstly, drying for 1-2 h at the normal pressure and 60 ℃; drying at 80 deg.C under 0.04MPa for 4 hr, and standing in a fume hood for 10min; drying at 120 deg.C under 0.06MPa for 2 hr, and standing in a fume hood for 20min; drying at 150 deg.C under 0.08MPa for 2 hr, and standing in a fume hood for 30min; drying at 200 deg.C under 0.09MPa for 2 hr, and standing in a fume hood for 40min; finally, drying for 2 hours at 200 ℃ under 0.1MPa, and standing for 40 minutes in a fume hood;

the step heat treatment is as follows: placing the dried wet film between heating iron plates of a vulcanizing press, quickly heating to 250 ℃, slowly reducing the temperature to 215 ℃, preserving the heat for 30min, and performing step heat treatment, wherein the first stage is hot-pressed for 20min under 2.5Mpa and 200 ℃; in the second stage, 5Mpa, heating to 2 ℃ and hot-pressing for 20min; in the third stage, 7.5Mpa, heating to 2 ℃ and hot-pressing for 15min; fourth, heating to 2 deg.C under 10Mpa, and hot-pressing for 15min; in the fifth stage, 12.5Mpa, heating to 2 ℃ and hot-pressing for 10min; in the sixth stage, 15Mpa and 2 ℃ are heated, and hot pressing is carried out for 10min;

the quenching treatment comprises the following steps: cooling to 0-25 ℃ by a cold water treatment device after the stepped heat treatment is completed.

2. The method of manufacturing a high temperature resistant composite dielectric according to claim 1, wherein the dielectric comprises 5 ITIC concentrations of 0.25wt%, 0.2wt%, 0.15wt%, 0.1wt% and 0.05wt%, respectively.

3. The method of manufacturing a high temperature resistant composite dielectric according to claim 1, wherein the dielectric comprises 4 ITIC concentrations of 0.25wt%, 0.2wt%, 0.15wt% and 0.1wt%, respectively.

4. The method of manufacturing a high temperature resistant composite dielectric according to claim 1, wherein the dielectric comprises 3 ITIC concentrations of 0.25wt%, 0.2wt% and 0.15wt%, respectively.

5. The method of claim 1, wherein the mass ratio of PEI to PESU is 9:1, 8:2, 7:3 or 6:4.

6. The method of claim 1, wherein the injector needles of the spinning precursors of (2) of different ITIC concentrations are applied with different voltages.

7. Use of a high temperature resistant composite dielectric according to claim 1 for rapid charge and discharge applications.