CN114481452B

CN114481452B - Capacitor composite film, preparation method thereof and capacitor

Info

Publication number: CN114481452B
Application number: CN202111657355.4A
Authority: CN
Inventors: 冯宇; 张灵; 周黎宣; 迟庆国; 陈庆国; 周远翔
Original assignee: Harbin University of Science and Technology
Current assignee: Harbin University of Science and Technology
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2023-08-22
Anticipated expiration: 2041-12-30
Also published as: CN114481452A

Abstract

The application provides a capacitor composite film, a preparation method thereof and a capacitor, wherein the method comprises the following steps: (1) Mixing a first polymer and a first inorganic substance to form a first suspension; (2) Forming a first film of the first suspension on a receiver by directional spinning; (3) Forming a second polymer on at least part of the surface of the first film by directional spinning to obtain a capacitor composite film. Therefore, the capacitor composite film can be formed by directional spinning at normal temperature and normal pressure, a vacuumizing link is avoided, the process is simpler, industrialization is easy to realize, and the prepared capacitor composite film has high energy storage density, high discharge efficiency and high-temperature-resistant working capacity.

Description

Capacitor composite film, preparation method thereof and capacitor

Technical Field

The application relates to the technical field of capacitors, in particular to a capacitor composite film, a preparation method thereof and a capacitor.

Background

Polymers are widely used as dielectric materials in dielectric capacitors, which are key components of various circuits in power electronics, and in practical applications are often high power, high current and high temperature operating conditions, and therefore, development of dielectric materials with high energy storage density and high temperature operating capability suitable for high temperature dielectric energy storage capacitor applications is highly desirable. At present, the preparation of the polymer-based nanocomposite is mainly realized by a Chemical Vapor Deposition (CVD) method and a physical magnetron sputtering (PVD) technology, the CVD method has complicated process and low yield, a vacuumizing device is required to be added in the production flow of preparing the polymer film, the current industrial production of the polymer film mainly depends on material mixing, heating and hot pressing and stretching to form a film, the preparation speed is relatively high, the vacuum chamber of the vacuum device is relatively small, only a small amount of film can be prepared each time, the steps of pumping and deflating when the polymer film is fed into the device are complicated and a large amount of time is required (2-4 hours are required for preparing one film), the device is incompatible with the industrial production equipment of the polymer film, the situation that the common film is produced in a large quantity and the yield of the composite film is extremely low can occur; secondly, the whole set of vacuum pumping equipment needs a series of equipment such as a vacuum pump, the equipment is very expensive and has high requirements on the working environment, and particularly, during the working period of the equipment, the working environment is kept clean, the equipment needs to be checked regularly, a large amount of manpower and material resources are consumed, and the industrial production requirement is not met. For the above reasons, the technology of preparing composite dielectric thin films by CVD and PVD is impossible to realize industrial mass production.

Therefore, the current preparation method of the capacitor composite film needs to be further improved.

Disclosure of Invention

The present application aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present application is to provide a capacitor composite film, a method for manufacturing the same, and a capacitor, wherein the method does not need a vacuum environment, is compatible with the existing film manufacturing process, has a simple process, is easy to realize industrialization, and the manufactured capacitor composite film has high energy storage density, high discharge efficiency and high-temperature-resistant working capacity.

In one aspect of the present application, a method of preparing a capacitor composite film is presented, comprising: (1) Mixing a first polymer and a first inorganic substance to form a first suspension; (2) Forming a first film of the first suspension on a receiver by directional spinning; (3) Forming a second polymer on at least part of the surface of the first film by directional spinning to obtain a capacitor composite film. Therefore, the capacitor composite film can be formed by directional spinning at normal temperature and normal pressure, a vacuumizing link is avoided, the process is simpler, industrialization is easy to realize, and the prepared capacitor composite film has high energy storage density, high discharge efficiency and high-temperature-resistant working capacity.

According to some embodiments of the application, the method further comprises: (4) Mixing a third polymer and a second inorganic substance to form a second suspension, and forming a third film on at least part of the surface of the second film far from the first film by directional spinning to obtain the capacitor composite film. Therefore, the formed capacitor composite film has a sandwich structure, has high energy density and discharge efficiency, and is suitable for normal temperature and high temperature capacitor energy storage application.

According to some embodiments of the present application, the capacitor composite film prepared in the step (3) is subjected to a heat pressing treatment. Thereby, a flat capacitor composite film is formed.

According to some embodiments of the present application, the capacitor composite film prepared in the step (4) is subjected to a hot pressing treatment. Thus, a flat sandwich-structured capacitor composite film is formed.

According to some embodiments of the application, the first polymer, the second polymer, and the third polymer are each independently selected from at least one of PEI, PI, PMMA, PC, PET, PEN and PVDF.

According to some embodiments of the application, the first and second inorganics are each independently selected from at least one of alumina, magnesia, aluminum nitride, boron nitride, silicon carbide, and silicon oxide.

According to some embodiments of the application, the first film has a thickness of 1 to 5 microns.

According to some embodiments of the application, the second film has a thickness of 10 to 30 microns.

According to some embodiments of the application, the third film has a thickness of 1 to 5 microns.

According to some embodiments of the application, the first mineral is present in an amount of 1% to 5% by volume based on the total volume of the first suspension.

According to some embodiments of the application, the second mineral is present in an amount of 1% to 5% by volume based on the total volume of the second suspension.

In another aspect of the present application, a capacitor composite film is provided, prepared by the method described above. Therefore, the capacitor composite film has all the characteristics and advantages of the capacitor composite film prepared by the method, which are not repeated herein, and generally has at least the advantages of simple preparation process, high energy storage density, high discharge efficiency and high temperature resistance.

In yet another aspect of the present application, a capacitor is provided comprising the foregoing capacitor composite film. Therefore, the capacitor has all the characteristics and advantages of the capacitor composite film, which are not described herein, and generally has at least the advantages of high energy storage density, high discharge efficiency and long service life.

Drawings

The foregoing and/or additional aspects and advantages of the application will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic flow chart of a method for producing a capacitor composite film according to an embodiment of the present application;

FIG. 2 shows performance test charts of examples 1-2 and comparative examples 1-4 of the present application;

FIG. 3 shows a discharge energy density test chart of comparative example 1 of the present application;

FIG. 4 shows a discharge energy density test chart of example 1 of the present application;

FIG. 5 shows a discharge energy density test chart of example 2 of the present application;

FIG. 6 shows a discharge energy density test chart of comparative example 2 of the present application;

FIG. 7 shows a discharge energy density test chart of comparative example 3 of the present application;

FIG. 8 shows a discharge energy density test chart of comparative example 4 of the present application;

FIG. 9 shows graphs of leakage current densities of examples 1-2 and comparative examples 1-4 of the present application;

FIG. 10 shows graphs of the dielectric constants of examples 1-2 and comparative examples 1-4 of the present application;

FIG. 11 shows graphs for testing dielectric loss for examples 1-2 and comparative examples 1-4 of the present application.

Detailed Description

Embodiments of the present application are described in detail below. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

In one aspect of the present application, a method of preparing a capacitor composite film is presented, comprising: (1) Mixing a first polymer and a first inorganic substance to form a first mixed solution; (2) Forming a first film on the receiver from the first mixed solution by directional spinning; (3) Forming a second polymer on at least part of the surface of the first film by directional spinning to obtain a capacitor composite film. Therefore, the capacitor composite film can be formed by directional spinning at normal temperature and normal pressure, a vacuumizing link is avoided, the process is simpler, industrialization is easy to realize, and the prepared capacitor composite film has high energy storage density, high discharge efficiency and high-temperature-resistant working capacity.

The principle of the present application capable of achieving the above advantageous effects will be briefly described as follows:

as described above, the polymer-based nanocomposite is currently prepared by Chemical Vapor Deposition (CVD) and physical magnetron sputtering (PVD), which has a low complicated CVD process and low yield, and PVD requires the addition of a vacuum apparatus in the production process of preparing a polymer film, which is not possible in industry, the size of the vacuum chamber is very limited, and if the vacuum apparatus is added in industrial production, the yield of the product is greatly reduced. The polymer film is formed by the high-speed directional spinning method, a vacuum device is not needed in the process, the polymer film can be prepared only by glue preparation, spinning and hot pressing processes, the process is simple, industrialization is easy to realize, meanwhile, the method is compatible with the existing film process, the production cost is reduced to a certain extent, the industrialization feasibility is improved, and the prepared polymer film has high energy storage density, high discharge efficiency and high-temperature-resistant working capacity.

In the following, various steps of the method are described in detail, referring to fig. 1, according to an embodiment of the present application, the method may include:

s100: glue compounding

In this step, the first polymer and the first inorganic are mixed to form a first suspension. According to some embodiments of the application, the first inorganic substance is present in an amount of 1% to 5% by volume, based on the total volume of the first suspension, and in particular may be present in an amount of 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% etc., whereby the energy storage properties of the film are better. The inventors found that if the volume content of the first inorganic substance is too small, the first inorganic substance content is small, and the improvement of the breakdown strength is limited; if the volume content of the first inorganic substance is too large, electric field distortion easily occurs at the interface due to a large dielectric difference between the first inorganic substance and the first polymer, thereby causing a decrease in breakdown field strength. According to some embodiments of the present application, the mixing manner of the first inorganic substance and the first polymer is not particularly limited as long as the first inorganic substance can form a uniform suspension in the first polymer, and specifically, according to the present application, the first inorganic substance may be added to the first polymer and stirred for 8 to 12 hours at a stirring speed of 500r/min. In order to disperse the first inorganic substance in the first polymer more uniformly, the suspension may be subjected to ultrasonic treatment, and according to some embodiments of the present application, the ultrasonic treatment time is not particularly limited, and one skilled in the art may select according to the kind and particle size of the first inorganic substance and the concentration of the suspension, so long as a uniform first suspension is formed, for example, ultrasonic treatment may be performed for 0.5 to 1 hour. According to some embodiments of the present application, the first inorganic material refers to an inorganic material with a high forbidden band width, specifically, the first inorganic material includes, but is not limited to, at least one of alumina, magnesia, aluminum nitride, boron nitride, silicon carbide and silicon oxide, and the first inorganic material with a wide band gap can increase the charge injection barrier height at the electrode/dielectric interface, can effectively inhibit leakage current, remarkably reduce conductance loss and improve breakdown performance. According to other embodiments of the present application, the type of first polymer is not particularly limited, e.g., the first polymer includes, but is not limited to, at least one of PEI, PI, PMMA, PC, PET, PEN and PVDF, and such a polymer has excellent electrical insulation properties, dielectric constant and flexibility, which are desirable choices for energy storage materials.

S200: forming a first film by directional spinning

In this step, the first suspension is formed into a first film on the receiver by directional spinning. Specifically, the first suspension is sucked into a needle tube and fixed on one side, a layer of tinfoil is paved on a high-speed orientation machine, and the first suspension is orderly arranged on the tinfoil under the action of an electric field through orientation spinning, so that a uniform film is formed. According to some embodiments of the present application, the distance between the needle and the high speed direction finder, the angle between the needle and the high speed direction finder, the positive voltage at the needle, the negative voltage at the high speed direction finder are not particularly limited, and it should be understood by those skilled in the art that the types of the first inorganic substance and the first polymer in the first suspension are different, and experimental parameters during spinning may be different. In particular, according to the present application, the distance between the needle and the high speed direction finder during the directional spinning process may be 10 to 20cm, and in particular, may be 11cm, 12cm, 13cm, 14cm, 15cm, 16cm, 17cm, 18cm, 19vm, etc., thereby forming a uniform first film. According to some embodiments of the application, the needle may be at an angle of 30 to 60 degrees, specifically 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, etc. to the high speed orienter, thereby forming a uniform first film. According to other embodiments of the application, the voltage at the needle may be 5-15 kV, in particular 6kV, 7kV, 8kV, 9kV, 10kV, 11kV, 12kV, 13kV, 14kV etc., whereby a uniform first film is formed. According to other embodiments of the present application, the voltage at the high speed orienter may be-15 kV to-5 kV, specifically, -14kV, -13kV, -12kV, -11kV, -10kV, -9kV, -8kV, -7kV, and-6 kV, etc., thereby forming a uniform first film.

According to some embodiments of the present application, the thickness of the first thin film is not particularly limited as long as the requirement of the capacitor on the thin film is satisfied, and specifically, according to the present application, the thickness of the first thin film may be 1 to 5 micrometers, for example, may be 1.5 micrometers, 2 micrometers, 2.5 micrometers, 3 micrometers, 3.5 micrometers, 4 micrometers, 4.5 micrometers, and the like, thereby, by controlling the thickness of the single-layer thin film, the finally formed composite thin film is prevented from being too thick to satisfy the requirement of the capacitor on the thickness of the thin film, and on the basis of this, the energy storage characteristic of the composite thin film is effectively improved. The inventor finds that if the thickness of the first film is too thin, the requirements on the preparation process are higher, and the precision of the prepared first film is poorer; if the thickness of the first film is too thick, the whole of the finally formed composite film is too thick, and part of capacitor cores are not assembled into the shell, so that the basic requirements of the capacitor films are not met.

S300: forming a second film by directional spinning

In this step, a second polymer is formed into a second film on at least a part of the surface of the first film by directional spinning so as to obtain a capacitor composite film. According to some embodiments of the present application, the process of directional spinning refers to the spinning process when forming the first film, but may not be exactly the same, so long as the second polymer can form a uniform and flat film on at least part of the surface of the first film, and the specific process is not described herein. According to other embodiments of the present application, the type of second polymer is not particularly limited, for example, the type of second polymer includes, but is not limited to, at least one of PEI, PI, PMMA, PC, PET, PEN and PVDF, and such second polymer has excellent electrical insulation properties, dielectric constant and flexibility, which are desirable choices for energy storage materials. According to some embodiments of the present application, the thickness of the second thin film is not particularly limited as long as the requirement of the capacitor on the thin film is satisfied, for example, the thickness of the second thin film may be 10 to 30 micrometers, specifically, may be 12 micrometers, 14 micrometers, 16 micrometers, 18 micrometers, 20 micrometers, 22 micrometers, 24 micrometers, 26 micrometers, 28 micrometers, etc., and may save space, reduce production cost, and the second thin film of this thickness has better pressure resistance and higher safety. The inventors found that if the thickness of the second film is too thin, the pressure resistance of the second film is reduced to some extent, and if used in a circuit, there is a certain risk; if the thickness of the second film is too thick, a large installation volume is required, and the production cost is high.

According to some embodiments of the application, when the receiver used is cylindrical, the preparation of the capacitor composite film further comprises a autoclave. Specifically, the capacitor composite film is dried, and the temperature and time of drying are not particularly limited, and may be selected by one skilled in the art according to the kind and thickness of the composite film. After drying, the film is hot-pressed, the hot-pressing temperature and pressure are not particularly limited, so long as the film is uniform and flat, for example, the flat capacitor composite film can be obtained by preheating the capacitor composite film at 180 ℃ for 5min, then heating to 190 ℃ for 15min, and finally cooling for 2min through a flat vulcanizing instrument.

According to some embodiments of the present application, in order to save time and cost, a third film may be formed on at least a portion of the surface of the second film remote from the first film by directional spinning, so as to obtain a capacitor composite film of a sandwich structure. According to some embodiments of the present application, the process of dispensing is also required when forming the third film, specifically, the third polymer and the second inorganic substance may be mixed, and the mixing manner refers to the process of dispensing the first film, which is not described herein. According to some embodiments of the application, the volume content of the second inorganic substance is 1% to 5%, specifically may be 1.5%, 2%, 2.5%, 3%, 3.5%, 4% and 4.5%, etc., based on the total volume of the second suspension, whereby the energy storage property of the film is better. It should be noted here that the volume content of the second inorganic substance may be the same or different from the volume content of the first inorganic substance, and may be freely selected by those skilled in the art. According to some embodiments of the present application, the second inorganic material includes, but is not limited to, at least one of alumina, magnesia, aluminum nitride, boron nitride, silicon carbide and silicon oxide, and the wide band gap second inorganic material can increase the charge injection barrier height at the electrode/dielectric interface, can effectively suppress leakage current, significantly reduce conductance loss, and improve breakdown performance. The type of the second inorganic substance and the type of the first inorganic substance may be the same or different, and may be freely selected by those skilled in the art. According to other embodiments of the present application, the type of third polymer is not particularly limited, for example, the type of third polymer includes, but is not limited to, at least one of PEI, PI, PMMA, PC, PET, PEN and PVDF, and such third polymer has excellent electrical insulation properties, dielectric constant and flexibility, which are ideal choices for energy storage materials. It should be noted here that the types of the first polymer, the second polymer and the third polymer may be the same or different, and may be freely selected by those skilled in the art.

According to some embodiments of the present application, the thickness of the third thin film is not particularly limited as long as the requirement of the capacitor on the thin film is satisfied, specifically, the thickness of the third thin film may be 1 to 5 micrometers, specifically, may be 1.5 micrometers, 2 micrometers, 2.5 micrometers, 3 micrometers, 3.5 micrometers, 4 micrometers, 4.5 micrometers, etc., thereby, by controlling the thickness of the single-layer thin film, the finally formed composite thin film is prevented from being too thick to satisfy the requirement of the capacitor on the thickness of the thin film, and on the basis, the energy storage characteristic of the composite thin film is effectively improved. The inventor finds that if the thickness of the third film is too thin, the requirements on the preparation process are higher, and the precision of the prepared third film is poorer; if the thickness of the third film is too thick, the whole of the finally formed composite film is too thick, and part of capacitor cores are not assembled into the shell, so that the basic requirements of the capacitor films are not met.

According to some embodiments of the present application, after the third film is formed, a heat pressing process is also required, and the heat pressing process refers to the heat pressing process after the second film is formed, which is not described herein.

Example 1

(1) Mixing BN and PEI to form a first suspension, wherein the volume ratio of BN in the first suspension is 2.5%, stirring for 8 hours after mixing, stirring at 500rpm, and carrying out ultrasonic treatment for 0.5 hour after stirring;

(2) Sucking BN/PEI suspension into a needle tube, spreading a layer of tinfoil on a high-speed orientation machine, controlling the distance between the needle head and the high-speed orientation machine to be 15cm, controlling the angle between the needle head and the high-speed orientation machine to be 45 degrees, controlling the voltage at the needle head to be 12kV, controlling the voltage at the high-speed orientation machine to be-12 kV, controlling the advancing speed of the needle tube to be 3mm/min, forming an electric field under the action of positive and negative voltages, spraying the suspension on the needle head under the action of the electric field, and orderly arranging the suspension on the tinfoil to form a film, thus obtaining the BN/PEI film;

(3) Sucking PEI into a needle tube, controlling the distance between the needle head and a high-speed orientation machine to be 15cm, controlling the angle between the needle head and the high-speed orientation machine to be 45 degrees, enabling the voltage at the needle head to be 12kV, enabling the voltage at the high-speed orientation machine to be-12 kV, enabling the pushing speed of the needle tube to be 3mm/min, forming an electric field under the action of positive and negative voltages, spraying PEI on the needle head under the action of the electric field, and orderly arranging PEI films on the surface of BN/PEI;

(4) Sucking the BN/PEI suspension in the step (1) into a needle tube, controlling the distance between the needle head and a high-speed orientation machine to be 15cm, controlling the angle between the needle head and the high-speed orientation machine to be 45 degrees, controlling the voltage at the needle head to be 12kV, controlling the voltage at the high-speed orientation machine to be-12 kV, controlling the advancing speed of the needle tube to be 3mm/min, forming an electric field under the action of positive and negative voltages, spraying the suspension on the needle head under the action of the electric field, and orderly arranging the suspension on the surface of PEI to form a BN/PEI film;

(5) And (3) taking down the composite film wet film obtained in the step (4), drying the composite film in an oven at 60 ℃ for 8 hours, carrying out hot pressing by using a flat vulcanizing instrument, preheating the composite film at 180 ℃ for 5 minutes, heating the composite film to 190 ℃ for hot pressing for 15 minutes, carrying out pressure of 15Mpa, and finally cooling the composite film for 2 minutes to obtain the capacitor composite film with the sandwich structure.

Example 2

The remainder of the procedure was as described in example 1, except that the volume fraction of BN in the first suspension was 5%.

Comparative example 1

Sucking PEI into a needle tube, paving a layer of tinfoil on a high-speed orientation machine, controlling the distance between a needle head and the high-speed orientation machine to be 15cm, controlling the angle between the needle head and the high-speed orientation machine to be 45 degrees, controlling the voltage at the needle head to be 12kV, controlling the voltage at the high-speed orientation machine to be-12 kV, controlling the advancing speed of the needle tube to be 3mm/min, forming an electric field under the action of positive and negative voltages, and spraying PEI on the needle head under the action of the electric field to form PEI films on the tinfoil in an ordered manner.

Comparative example 2

The remainder of the procedure was as described in example 1, except that the volume fraction of BN in the first suspension was 7.5%.

Comparative example 3

The remainder of the procedure is as in example 1, except that the volume fraction of BN in the first suspension is 10%.

Comparative example 4

The remainder of the procedure is as in example 1, except that the volume fraction of BN in the first suspension is 15%.

The composite films of examples 1 and 2, the PEI film of comparative example 1 and the composite films of comparative examples 2 to 4 were tested, and the test results are shown in FIGS. 2 to 11 of the drawings attached to the specification.

As can be seen from the drawing of the specification, compared with comparative examples 1-4, the capacitor composite film prepared by high-speed directional spinning in examples 1 and 2 has high energy density and discharge efficiency, wherein when the volume ratio of BN in the BN/PEI film is 1% -5%, the breakdown field strength resistance is better, and when the volume ratio of BN is 5%, the breakdown field strength resistance can be improved by 20%; the dielectric constant of the capacitor composite film is improved compared with that of a single-layer PEI film, and the dielectric loss is basically unchanged; the leakage current density of the capacitor composite film is reduced compared with a single-layer PEI film.

In the present disclosure, the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying a number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims

1. A method of making a capacitor composite film comprising:

(1) Mixing a first polymer and a first inorganic substance to form a first suspension;

(2) Forming a first film of the first suspension on a receiver by directional spinning;

(3) Forming a second polymer on at least part of the surface of the first film by directional spinning to obtain a capacitor composite film;

(4) Mixing a third polymer and a second inorganic substance to form a second suspension, and forming a third film on at least part of the surface of the second film far away from the first film by directional spinning to obtain a capacitor composite film;

carrying out hot pressing treatment on the capacitor composite film prepared in the step (4),

the first polymer, the second polymer and the third polymer are PEI,

the directional spinning meets the following conditions:

the distance between the needle head and the high-speed orientation machine in the process of oriented spinning is 10-20 cm;

the angle between the needle head and the high-speed orientation machine is 30-60 degrees;

the voltage at the needle head is 5-15 kV;

the voltage at the high-speed orientation machine is-15 kV to-5 kV,

the first inorganic matter and the second inorganic matter are respectively and independently selected from at least one of aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, silicon carbide and silicon oxide;

the thickness of the first film is 1-5 microns;

the thickness of the second film is 10-30 microns;

the thickness of the third film is 1-5 microns.

2. The method of claim 1, wherein the first mineral is present in an amount of 1% -5% by volume based on the total volume of the first suspension.

3. The method of claim 1, wherein the volume content of the second inorganic substance is 1% -5% based on the total volume of the second suspension.

4. A capacitor composite film prepared by the method of any one of claims 1 to 3.

5. A capacitor comprising the capacitor composite film of claim 4.