A method for improving the energy storage properties of BOPP film based on LB film interface deposition modification

Abstract

The invention discloses a method for improving the energy storage characteristics of a BOPP film modified by LB film interface deposition, and belongs to the technical field of capacitor metallized dielectric films. The BOPP film is surface treated; 1,3,5-tris(4-aminophenyl)benzene and 2,5-bis(octyloxy)terephthalaldehyde are respectively dissolved in an organic solvent; the two prepared solutions are mixed, and then dripped on the surface of ultrapure water spread in the LB film drawing machine slot, and left to volatilize the solution; the LB film drawing machine slide barrier speed is set to compress; glacial acetic acid is dripped to spread on the surface of ultrapure water in the LB film drawing machine slot, and left to react; the LB film drawing machine slide barrier speed is set to compress to form a two-dimensional covalent organic framework LB film; the two-dimensional covalent organic framework LB film is transferred to the surface of the BOPP film for deposition to form a composite film. The present invention suppresses electric field distortion and interface charge injection, improves film breakdown strength, and realizes the improvement of dielectric film energy storage density by depositing a layer of two-dimensional organic framework LB film with tightly arranged molecules on the BOPP film.

Description

Technical Field

[0001] The invention relates to the technical field of capacitor metallized dielectric films, and in particular to a method for improving the energy storage characteristics of a BOPP film based on LB film interface deposition modification. Background Art

[0002] In recent years, with the continuous development of power electronics technology, the demand for energy storage devices has continued to increase. Metallized film capacitors have the advantages of high power density, strong voltage resistance, and good self-healing properties. They have become the core energy storage devices in electromagnetic launch, electric vehicles, space shuttle power systems, offshore wind power generation, and medical defibrillators. Metallized film capacitors are mainly composed of dielectric films and electrodes. The characteristics of dielectric films are the key factors affecting the performance of capacitors.

[0003] Biaxially oriented polypropylene (BOPP) is the most widely used energy storage dielectric material in metallized film capacitors due to its high breakdown strength, low dielectric loss, high charge and discharge efficiency, and good self-healing performance. As power electronic equipment develops towards miniaturization and large capacity, higher requirements are placed on the energy storage density of metallized film capacitors. However, the energy storage density of biaxially oriented polypropylene film is low, and capacitors occupy a large volume in power electronic equipment, making it difficult to meet the development needs of energy storage devices. Langmuir-Blodgett (LB) film has the characteristics of tight and orderly molecular arrangement, and fewer defects at the electrode-two-dimensional organic framework LB film interface. Therefore, the present invention proposes a method for improving the energy storage characteristics of BOPP film based on LB film interface deposition modification. Summary of the invention

[0004] The purpose of the present invention is to provide a method for improving the energy storage characteristics of a BOPP film based on LB film interface deposition modification, so as to solve the problem of low energy storage density of the polypropylene film mentioned in the above background technology.

[0005] To achieve the above objectives, the present invention provides a method for improving the energy storage characteristics of BOPP film based on LB film interface deposition modification, in which a two-dimensional organic framework LB film is deposited on the BOPP film to inhibit electric field distortion and interface charge injection, improve the film breakdown strength, and achieve an increase in the energy storage density of the dielectric film.

[0006] Preferably, a method for improving the energy storage properties of a BOPP film based on LB film interface deposition modification specifically comprises the following steps:

[0007] (1) Surface treatment of BOPP film;

[0008] (2) dissolving 1,3,5-tri(4-aminophenyl)benzene and 2,5-bis(octyloxy)terephthalaldehyde in an organic solvent respectively;

[0009] (3) mixing the two solutions obtained in step (2), dropping the mixed solution onto the surface of ultrapure water in the LB film drawing machine tank, and allowing the mixed solution to stand until the solution evaporates;

[0010] (4) Setting the sliding barrier speed compression of the LB film drawing machine;

[0011] (5) adding glacial acetic acid dropwise to spread it on the surface of ultrapure water in the LB film drawing machine tank and allowing it to react;

[0012] (6) setting the sliding barrier speed of the LB film drawing machine to compress and form a two-dimensional covalent organic framework LB film;

[0013] (7) The two-dimensional covalent organic framework LB film is transferred to the surface of the BOPP film and deposited to form a composite film.

[0014] Preferably, the specific operation of step (1) is: washing the BOPP film with anhydrous ethanol and deionized water for 5 to 15 minutes, and then placing the washed BOPP film in a vacuum drying oven and drying it at 50 to 70° C. for 0.5 to 2 hours.

[0015] Preferably, in step (1), the thickness of the BOPP film is 3 to 10 μm.

[0016] Preferably, in step (2), the organic solvents for dissolving 1,3,5-tris(4-aminophenyl)benzene and 2,5-bis(octyloxy)terephthalaldehyde are chloroform and N,N-dimethylformamide, respectively.

[0017] Preferably, in step (3), the volume ratio between the 1,3,5-tris(4-aminophenyl)benzene solution and the 2,5-bis(octyloxy)terephthalaldehyde is 1:1.658.

[0018] Preferably, in step (5), the volume of glacial acetic acid is 350 μL.

[0019] Preferably, in steps (4) and (6), the sliding barrier speed of the LB film drawing machine is set to compress at a speed of 2.98 mm / min.

[0020] Preferably, in step (7), the two-dimensional covalent organic framework LB film is transferred to the surface of the BOPP film by a vertical pulling method at a film pulling speed of 0.5 mm / min.

[0021] Therefore, the present invention provides a method for improving the energy storage characteristics of a BOPP film based on LB film interface deposition modification, wherein a layer of a two-dimensional organic framework LB film with tightly ordered molecular arrangement is deposited on a biaxially oriented polypropylene film, a deep trap capable of capturing carriers is introduced at the electrode-dielectric interface, and the migration of interface charges into the interior of the BOPP is suppressed; the LB film reduces the interface defects of the electrode-dielectric film, and suppresses the interface charge migration and electric field distortion; thereby the breakdown field strength of the BOPP film is improved, and a composite film with high energy storage density and charge and discharge efficiency is obtained, thereby promoting the miniaturization and large-capacity development of metallized film capacitors.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The DC breakdown field strength diagram of the composite film prepared in the embodiment of the present invention and the common BOPP polypropylene film at 25°C;

[0024] Figure 2 The DC breakdown field strength diagram of the composite film prepared in the embodiment of the present invention and the common BOPP polypropylene film at 125°C;

[0025] Figure 3 The graph is a graph of energy storage density and charge-discharge efficiency of the composite film prepared in the embodiment of the present invention and a common BOPP polypropylene film at 25°C;

[0026] Figure 4 The graph is a graph of energy storage density and charge-discharge efficiency of the composite film prepared in the embodiment of the present invention and a common BOPP polypropylene film at 125°C. DETAILED DESCRIPTION

[0027] The present invention provides a method for improving the energy storage characteristics of a BOPP film based on LB film interface deposition modification, wherein a layer of a two-dimensional organic framework LB film with tightly and orderly molecular arrangement is deposited on the BOPP film, electric field distortion and interface charge injection are suppressed, the breakdown strength of the film is improved, and the energy storage density of the dielectric film is improved.

[0028] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a method for improving the energy storage properties of a BOPP film based on LB film interface deposition modification, and the specific steps are as follows:

[0031] (1) A BOPP film with a thickness of 7.5 μm was selected, and the BOPP film was cleaned in anhydrous ethanol and deionized water for 10 min respectively, and then the cleaned BOPP film was placed in a vacuum drying oven at a temperature of 60°C and dried for 1 h.

[0032] (2) 1,3,5-tri(4-aminophenyl)benzene is dissolved in chloroform to obtain a 1 mg / mL 1,3,5-tri(4-aminophenyl)benzene solution, and 2,5-bis(octyloxy)terephthalaldehyde is dissolved in N,N-dimethylformamide to obtain a 2,5-bis(octyloxy)terephthalaldehyde solution with a concentration of 1 mg / mL.

[0033] (3) The two completely dissolved solutions obtained in step (2) were mixed evenly in a volume ratio of 1:1.658. 70 μL of the mixed solution was taken and added dropwise to evenly spread the mixed solution on the surface of the ultrapure water in the LB tank. The mixture was allowed to stand for 30 min to allow the solvent to evaporate.

[0034] (4) Set the slide barrier of the LB film drawing machine to compress at a speed of 2.98 mm / min to a molding pressure of 3 mN / m.

[0035] (5) Spread 350 μL of glacial acetic acid evenly on the surface of ultrapure water in the LB tank and let it stand for 12 h to allow the reaction to complete.

[0036] (6) The slide barrier of the LB film drawing machine is set to compress at a speed of 2.98 mm / min to a film forming pressure to form a tightly arranged two-dimensional covalent organic framework LB film.

[0037] (7) A single layer of two-dimensional polymer was transferred to the surface of BOPP film using a vertical pulling method at a film pulling speed of 0.5 mm / min.

[0038] Figure 1 The DC breakdown field strength diagram of the composite film prepared in the embodiment of the present invention and the ordinary BOPP polypropylene film at 25° C. As can be seen from the figure, the breakdown field strength of the composite film at 25° C. is significantly improved compared with the ordinary BOPP film.

[0039] Figure 2 The DC breakdown field strength diagram of the composite film prepared in the embodiment of the present invention and the common BOPP polypropylene film at 125° C. As can be seen from the figure, the breakdown field strength of the composite film at 125° C. is improved.

[0040] Figure 3 The energy storage density and charge-discharge efficiency of the composite film prepared in the embodiment of the present invention and the common BOPP polypropylene film at 25° C. It can be seen from the figure that the energy storage density of the composite film at 25° C. is significantly improved while maintaining high charge-discharge efficiency.

[0041] Figure 4The energy storage density and charge-discharge efficiency of the composite film prepared in the embodiment of the present invention and the ordinary BOPP polypropylene film at 125° C. As can be seen from the figure, under high temperature environment, as the electric field intensity increases, the charge-discharge efficiency of the composite film remains relatively stable compared with the ordinary BOPP film, and the composite film has a higher energy storage density.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for improving the energy storage properties of BOPP film based on LB film interface deposition modification, characterized in that: Depositing the two-dimensional organic framework LB film on the BOPP film can suppress electric field distortion and interface charge injection, improve the film breakdown strength, and achieve an increase in the energy storage density of the dielectric film. The specific steps include: (1) Surface treatment of BOPP film; (2) dissolving 1,3,5-tri(4-aminophenyl)benzene and 2,5-bis(octyloxy)terephthalaldehyde in an organic solvent respectively; (3) mixing the two solutions obtained in step (2), dropping the mixed solution onto the surface of ultrapure water in the LB film drawing machine tank, and allowing the mixed solution to stand until the solution evaporates; (4) Setting the sliding speed compression of the LB film drawing machine; (5) adding glacial acetic acid dropwise to spread it on the surface of ultrapure water in the LB film drawing machine tank and allowing it to react; (6) setting the sliding barrier speed of the LB film drawing machine to compress and form a two-dimensional covalent organic framework LB film; (7) The two-dimensional covalent organic framework LB film is transferred to the surface of the BOPP film and deposited to form a composite film.

2. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: The specific operation of step (1) is: using anhydrous ethanol and deionized water to wash the BOPP film for 5 to 15 minutes, and then putting the washed BOPP film into a vacuum drying oven and drying it at 50 to 70° C. for 0.5 to 2 hours.

3. The method for improving the energy storage characteristics of a BOP P thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the step (1), the thickness of the BOPP film is 3 to 10 μm.

4. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the step (2), the organic solvents for dissolving 1,3,5-tris(4-aminophenyl)benzene and 2,5-bis(octyloxy)terephthalaldehyde are chloroform and N,N-dimethylformamide, respectively.

5. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the step (3), the volume ratio between the 1,3,5-tris(4-aminophenyl)benzene solution and the 2,5-bis(octyloxy)terephthalaldehyde is 1:1.

658.

6. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the step (5), the volume of glacial acetic acid is 350 μL.

7. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the steps (4) and (6), the sliding speed of the LB film drawing machine is set to compress at a speed of 2.98 mm / min.

8. The method for improving the energy storage characteristics of a BOPP thin film based on LB film interface deposition modification according to claim 1, characterized in that: In the step (7), the two-dimensional covalent organic framework LB film is transferred to the surface of the BOPP film by a vertical pulling method at a film pulling speed of 0.5 mm / min.

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