A polymer film with high energy storage density and low conduction loss, and preparation method and application thereof

Abstract

A polymer film with both high energy storage density and low conduction loss, and its preparation method and application. The present invention belongs to the field of polymer dielectric energy storage materials and their preparation. The purpose of the present invention is to solve the technical problems of low energy storage density and high conduction loss of polymer film capacitors. By regulating different sputtering powers and sputtering times, selecting appropriate substrate rotation speeds, substrate temperatures, and suitable target-substrate distances for sputtering, CoFe2O4 with different thicknesses is grown on the surface of the BOPP film as a magnetic surface functional layer. The surface roughness of the obtained functional layer is good, and no obvious defects appear. This magnetic functional layer can effectively improve the energy storage density of the capacitive film. In addition, the magnetic functional layer can not only increase the electron injection barrier, but also has a large remanent magnetization, which can generate a Lorentz force on electrons, regulate the electron transmission path, and reduce the conduction loss.

Description

Technical Field

[0001] The present invention belongs to the field of polymer dielectric energy storage materials and preparation thereof, and specifically relates to a polymer film having both high energy storage density and low conduction loss, and a preparation method and application thereof. Background Art

[0002] Dielectric capacitors have the advantages of high power density, fast charge and discharge rate, high open circuit voltage, and good temperature stability, and are widely used in new energy vehicle inverters, high pulse nuclear weapons, and flexible direct current transmission. Ceramics and polymers, as the most common dielectric materials, have received widespread attention and research. Although ceramic materials have a large relative dielectric constant, they withstand a very low breakdown field strength, the production process is relatively complex, and the mechanical flexibility is poor, which makes them inapplicable to highly integrated modern electronic devices. Polymer dielectrics have excellent mechanical toughness, high breakdown field strength, and simple production processes, and are increasingly used in modern industry. Therefore, in the production of polymer film capacitors, how to improve the energy storage density of polymer dielectrics becomes the key. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems of low energy storage density and high conduction loss of polymer film capacitors. The present invention provides a polymer film with high energy storage density and low conduction loss, and a preparation method and application thereof.

[0004] The purpose of the present invention is to achieve the following technical solutions:

[0005] One of the purposes of the present invention is to provide a polymer film having both high energy storage density and low conduction loss, wherein the polymer film is composited by a BOPP film and a CoFe2O4 layer obtained by magnetron sputtering on both sides of the BOPP film.

[0006] It is further defined that the BOPP film thickness is 10 μm.

[0007] It is further defined that the CoFe2O4 layer thickness is 80-330nm.

[0008] The second object of the present invention is to provide a method for preparing a polymer film having both high energy storage density and low conduction loss, wherein the preparation method is carried out according to the following steps:

[0009] S1: Fix the cleaned BOPP film on the substrate in the sputtering chamber, and use magnetron sputtering technology to grow CoFe2O4 layers on both sides of the BOPP film to obtain a polymer film;

[0010] S2: Use a steady magnetic field generator to magnetize the polymer film to obtain a polymer film with high energy storage density and low conduction loss.

[0011] It is further defined that the BOPP film in S1 is washed with deionized water and then wiped with alcohol.

[0012] It is further defined that the specific process of magnetron sputtering in S1 is: using CoFe2O4 as the target material, adjusting the flow ratio of argon and oxygen after vacuuming, regulating the sputtering power and time, and growing the CoFe2O4 layer on both sides of the BOPP film.

[0013] It is further defined that the target-substrate distance is 6-10 cm.

[0014] It is further defined that the substrate rotation speed is 5-7 rpm.

[0015] Further limit, vacuum to 2.0-3.0×10 -4 Pa.

[0016] It is further defined that the flow ratio of argon to oxygen is (2-4):1, and the pressure of the vacuum chamber is 1.1-1.3Pa.

[0017] It is further defined that the sputtering power is 40-60 W and the sputtering time is 0.25-1.5 h.

[0018] It is further defined that the magnetic field strength in S2 is 1.5 T and the magnetization time is 15-30 min.

[0019] A third object of the present invention is to provide a polymer film having both high energy storage density and low conduction loss for use in capacitors.

[0020] Compared with the prior art, the present invention has the following significant effects:

[0021] (1) The present invention controls different sputtering powers and times, selects appropriate substrate speed and substrate temperature, and selects appropriate distance from the target material to the substrate for sputtering, grows CoFe2O4 of different thicknesses on BOPP as a magnetic surface functional layer, and performs magnetization treatment for different times after film formation. The surface roughness of the obtained functional layer is good and no obvious defects occur. The magnetic functional layer can well improve the energy storage density of the capacitor film and has a wide range of application scenarios.

[0022] (2) The CoFe2O4 magnetic functional layer grown by the present invention improves the potential barrier between the electrode and the film, hindering Schottky injection under high temperature and high field; and the larger relative dielectric constant and the generation of interface polarization increase the dielectric constant of the composite film to a higher value.

[0023] (3) In addition, the presence of magnetic domains in the CoFe2O4 magnetic functional layer grown by the present invention ensures that the surface functional layer still has a large residual magnetization after magnetization. Under the synergistic effect of the electric field and the magnetic field, the transmission path of electrons is regulated and the conduction loss is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of a polymer film having high energy storage density and low conduction loss prepared by the present invention;

[0025] Figure 2 XRD patterns of polymer films with high energy storage density and low conduction loss prepared in different embodiments;

[0026] Figure 3 The charge and discharge efficiency and discharge energy density of polymer films with high energy storage density and low conduction loss prepared in different embodiments;

[0027] Figure 4 hysteresis loop comparison diagram of the polymer film with high energy storage density and low conduction loss prepared in Example 1 at different annealing temperatures;

[0028] Figure 5 Comparison of loss performance of polymer films with high energy storage density and low conduction loss prepared in different embodiments. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0031] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0032] When equivalent, concentration or other value or parameter is represented by the range limited by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the scope is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the scope is intended to include its end value and all integers and fractions within the scope. In the present application specification and claims, range limitation can be combined and / or interchanged, if these ranges are not otherwise stated, include all sub-ranges contained therein.

[0033] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0034] The "one embodiment" or "embodiment" of the present invention refers to a specific feature, structure or characteristic that can be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] Embodiment 1:

[0036] The method for preparing a polymer film with high energy storage density and low conduction loss in this embodiment is carried out by the following steps:

[0037] S1:

[0038] The BOPP film (thickness of 10 μm) was washed with deionized water, then wiped with alcohol, and then the cleaned BOPP film was fixed on the substrate of the sputtering chamber;

[0039] Using CoFe2O4 as the target, the vacuum degree of the chamber was drawn to 2.0×10 -4 Pa, oxygen (purity 99.99%) was used as the protective gas, argon (99.99%) was used as the sputtering gas, the flow ratio of argon to oxygen was adjusted to 3:1, the vacuum chamber pressure was 1.1 Pa, the target substrate distance was 8 cm, the substrate rotation speed was 6 rpm, the sputtering power was 50 W, the sputtering time was 0.5 h, and a CoFe2O4 layer with a thickness of 120 nm was obtained. After the BOPP film was turned over, the CoFe2O4 layer was grown on the other side under the same magnetron sputtering conditions to obtain a polymer film;

[0040] S2: Using a constant magnetic field generator, the polymer film was magnetized for 15 min at a magnetic field strength of 1.5 T to obtain a polymer film with high energy storage density and low conduction loss, denoted as FBF-0.5. The structural diagram is shown in Figure 1 shown.

[0041] Embodiment 2:

[0042] The method for preparing a polymer film with high energy storage density and low conduction loss in this embodiment is carried out by the following steps:

[0043] S1:

[0044] The BOPP film (thickness of 10 μm) was washed with deionized water, then wiped with alcohol, and then the cleaned BOPP film was fixed on the substrate of the sputtering chamber;

[0045] Using CoFe2O4 as the target, the vacuum degree of the chamber was drawn to 2.0×10 -4 Pa, oxygen (purity 99.99%) was used as the protective gas, argon (99.99%) was used as the sputtering gas, the flow ratio of argon to oxygen was adjusted to 3:1, the vacuum chamber pressure was 1.1 Pa, the target substrate distance was 8 cm, the substrate rotation speed was 6 rpm, the sputtering power was 50 W, the sputtering time was 1 h, and a CoFe2O4 layer with a thickness of 230 nm was obtained. After the BOPP film was turned over, the CoFe2O4 layer was grown on the other side under the same magnetron sputtering conditions to obtain a polymer film;

[0046] S2: Using a constant magnetic field generator, the polymer film was magnetized at a magnetic field strength of 1.5 T for 15 minutes to obtain a polymer film with high energy storage density and low conduction loss, which was recorded as FBF-1.

[0047] Embodiment 3:

[0048] The method for preparing a polymer film with high energy storage density and low conduction loss in this embodiment is carried out by the following steps:

[0049] S1:

[0050] The BOPP film (thickness of 10 μm) was washed with deionized water, then wiped with alcohol, and then the cleaned BOPP film was fixed on the substrate of the sputtering chamber;

[0051] Using CoFe2O4 as the target, the vacuum degree of the chamber was drawn to 2.0×10 -4Pa, oxygen (purity 99.99%) was used as the protective gas, argon (99.99%) was used as the sputtering gas, the flow ratio of argon to oxygen was adjusted to 3:1, the vacuum chamber pressure was 1.1 Pa, the target substrate distance was 8 cm, the substrate rotation speed was 6 rpm, the sputtering power was 50 W, the sputtering time was 1.5 h, and a CoFe2O4 layer with a thickness of 330 nm was obtained. After the BOPP film was turned over, the CoFe2O4 layer was grown on the other side under the same magnetron sputtering conditions to obtain a polymer film;

[0052] S2: Using a constant magnetic field generator, the polymer film was magnetized at a magnetic field strength of 1.5 T for 15 minutes to obtain a polymer film with high energy storage density and low conduction loss, which was recorded as FBF-1.5.

[0053] Embodiment 4:

[0054] The method for preparing a polymer film with high energy storage density and low conduction loss in this embodiment is carried out by the following steps:

[0055] S1:

[0056] The BOPP film (thickness of 10 μm) was washed with deionized water, then wiped with alcohol, and then the cleaned BOPP film was fixed on the substrate of the sputtering chamber;

[0057] Using CoFe2O4 as the target, the vacuum degree of the chamber was drawn to 2.0×10 -4 Pa, oxygen (purity 99.99%) was used as the protective gas, argon (99.99%) was used as the sputtering gas, the flow ratio of argon to oxygen was adjusted to 3:1, the vacuum chamber pressure was 1.1 Pa, the target substrate distance was 8 cm, the substrate rotation speed was 6 rpm, the sputtering power was 50 W, the sputtering time was 0.25 h, and a CoFe2O4 layer with a thickness of 80 nm was obtained. After the BOPP film was turned over, the CoFe2O4 layer was grown on the other side under the same magnetron sputtering conditions to obtain a polymer film;

[0058] S2: Using a constant magnetic field generator, the polymer film was magnetized at a magnetic field strength of 1.5 T for 15 minutes to obtain a polymer film with high energy storage density and low conduction loss, which was recorded as FBF-0.25.

[0059] Detection test

[0060] The polymer films with high energy storage density and low conduction loss obtained in Examples 1-3 were subjected to XRD tests, and the results were as follows: Figure 2As shown in the figure, the diffraction peaks at 14.1°, 16.9°, 18.5° and 25.5° correspond to the (110), (040), (130) and (060) crystal planes, respectively. The diffraction peak characteristics indicate that the BOPP film is an α-crystalline type.

[0061] The energy storage performance of the polymer film with high energy storage density and low conduction loss obtained in Examples 1-4 was tested, and the results are as follows: Figure 3 As shown in the figure, at 120°C, the charge and discharge efficiency and discharge energy density of BOPP films with different coating thicknesses are shown. The figure shows that the best charge and discharge efficiency is 83.8% and the discharge energy density is 2.66 J / cm 3 , indicating that growing an appropriate amount of CoFe2O4 as a magnetic surface functional layer improves the cracking efficiency at high temperatures, reduces the heat generation of BOPP at high temperatures, increases the usage scenarios of BOPP, and can also increase the charging and discharging efficiency and discharge energy density of BOPP films.

[0062] In order to illustrate the magnetic properties of the polymer film obtained in Example 1 of the present invention, the polymer film obtained in Example 1 was annealed at 500° C. and 700° C. for 3 h, and then the magnetic properties were tested. The results are as follows: Figure 4 As shown, it shows that the CoFe2O4 film has magnetic properties, and compared with the heat treatment at 500℃, annealing at 700℃ is more conducive to the increase of the saturation magnetization intensity of the CoFe2O4 film.

[0063] The loss performance of the polymer film with high energy storage density and low conduction loss obtained in Examples 1-4 was tested, and the results are as follows: Figure 5 As shown in the figure, at 120℃ and 200kV / mm, the leakage current first increases and then decreases with the increase of sputtering time. When the sputtering time is 0.5h, the leakage current density is the minimum, which is 5.35×10 -8 A / cm 2 .

[0064] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a polymer film having both high energy storage density and low conduction loss, characterized in that The polymer film with high energy storage density and low conduction loss is composed of a BOPP film and a CoFe2O4 layer obtained by magnetron sputtering on both sides of the BOPP film. When used in a capacitor, the charging and discharging efficiency is 83.8% and the leakage current density is 5.35×10 - 8 A / cm 2 ; The preparation method is carried out according to the following steps: S1： A BOPP film with a thickness of 10 μm was washed with deionized water, then wiped with alcohol, and then the cleaned BOPP film was fixed on the substrate of the sputtering chamber; Using CoFe2O4 as the target, the vacuum degree of the chamber was drawn to 2.0×10 -4 Pa, oxygen was used as the protective gas, argon was used as the sputtering gas, the flow ratio of argon to oxygen was adjusted to 3:1, the vacuum chamber pressure was 1.1Pa, the target substrate distance was 8cm, the substrate rotation speed was 6rpm, the sputtering power was 50W, the sputtering time was 0.5h, and a CoFe2O4 layer with a thickness of 120nm was obtained. After the BOPP film was turned over, the CoFe2O4 layer was grown on the other side under the same magnetron sputtering conditions to obtain a polymer film; S2: Using a constant magnetic field generator, the polymer film is magnetized at a magnetic field strength of 1.5 T for 15 minutes to obtain a polymer film with both high energy storage density and low conduction loss.

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