High-temperature energy storage meta-aramid dielectric film and preparation method thereof

Abstract

The invention discloses a preparation method of a high-temperature energy-storage meta-aramid dielectric film, which comprises the following steps: A, mixing and stirring a meta-aramid polymer solution and a polar solvent to obtain a meta-aramid solution; b, standing the meta-position aramid fiber solution, performing vacuum defoaming, uniformly coating the meta-position aramid fiber solution on the surface of the plate, performing high-temperature drying to completely volatilize the solvent, and removing the meta-position aramid fiber solution from the surface of the plate to obtain a preformed meta-position aramid fiber film; c, soaking the preformed meta-aramid film in deionized water to remove impurities; d, using magnetron sputtering to generate a silicon nitride deposition layer on the surface of the meta-aramid film after impurity removal; and E, carrying out annealing treatment on the meta-aramid film with the silicon nitride deposition layer. According to the invention, the defects in the prior art can be overcome, and the dielectric property of meta-aramid is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer film material preparation, in particular to a high-temperature energy storage meta-aramid dielectric film and a preparation method thereof. Background Art

[0002] Polymer film materials are ideal dielectric materials for electrostatic capacitors due to their excellent charge and discharge rates, high power density, outstanding breakdown strength, good self-healing properties, and ease of processing. The rapid development of new energy vehicles, photovoltaic grid-connected systems, oil and gas exploration, and aerospace has placed increasingly stringent demands on the high-temperature (≥150°C) energy storage performance of polymer film capacitors.

[0003] Biaxially oriented polypropylene (BOPP) is one of the most commercially successful capacitor film materials. However, its mechanical and heat resistance properties suffer from significant drawbacks: when temperatures exceed its glass transition temperature (Tg), BOPP film completely loses its mechanical stability, requiring its maximum operating temperature to be controlled below 105°C for short-term operation and no higher than 85°C for long-term operation. More critically, when ambient temperatures rise above 85°C, BOPP film experiences significant conductive losses, and its discharge efficiency and energy density also decline sharply. These performance deficiencies severely limit the application of BOPP film in high-temperature environments.

[0004] Aramid materials, with their excellent high-temperature resistance, insulation, and mechanical properties, are widely used in firefighting uniforms, industrial high-temperature filtration, electrical insulation, and aerospace materials. Meta-aramid is one of the most widely used aramid materials due to its good processing properties. However, due to its loose and disordered molecular chains, meta-aramid's performance cannot meet the requirements of high-performance energy storage films. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-temperature energy storage meta-aramid dielectric film and a preparation method thereof, which can solve the deficiencies of the prior art and improve the dielectric properties of meta-aramid.

[0006] In order to solve the above technical problems, the technical inventions adopted by the present invention are as follows.

[0007] A method for preparing a high-temperature energy storage meta-aramid dielectric film, characterized by comprising the following steps:

[0008] A. mixing a meta-aramid polymer solution and a polar solvent to obtain a meta-aramid solution;

[0009] B. The meta-aramid solution is allowed to stand and defoamed in vacuum, and then evenly coated on the surface of the plate. After high-temperature drying, the solvent is completely evaporated, and the preformed meta-aramid film is peeled off from the surface of the plate;

[0010] C. Soaking the preformed meta-aramid film in deionized water to remove impurities;

[0011] D. Using magnetron sputtering to form a silicon nitride deposition layer on the surface of the meta-aramid film after impurities are removed;

[0012] E. Annealing the meta-aramid film with the deposited silicon nitride layer.

[0013] Preferably, in step A, the polar solvent is N,N-dimethylacetamide or N-methylpyrrolidone, the mass fraction of the meta-aramid solution is 8-10wt%, the mixing speed is 200-800rpm, the mixing temperature is 80-150°C, and the mixing time is 2-12h.

[0014] Preferably, in step B, the standing time is 6 to 24 hours, the defoaming temperature is room temperature, and the defoaming vacuum degree is -0.1 MPa.

[0015] Preferably, in step B, the material of the plate is glass, metal or polyimide, and the coating method is spin coating, dip coating, wire rod coating or blade coating.

[0016] Preferably, in step B, the drying method is air drying or vacuum drying, and the drying temperature is 60-100°C.

[0017] Preferably, in step C, the deionized water soaking temperature is room temperature to 80° C., the soaking time is 4 to 7 days, and the dynamic water change frequency is 3 to 5 times per day.

[0018] Preferably, in step D, a silicon wafer with a purity greater than 99.9999% is used as the target material, a mixture of argon and ammonia is used as the working gas, the chamber pressure is 0.2-0.5 Pa, the flow rate ratio of argon to ammonia is 1:1-1:2, and the sputtering power density is 1.5-2 W / cm 2 , the temperature during the sputtering process of the meta-aramid film is controlled at 170-180°C, and the thickness of the silicon nitride deposition layer is 10-20nm.

[0019] Preferably, in step E, a two-stage annealing is adopted, wherein the annealing temperature of the first stage is 200±10° C., and the annealing time is 1 to 3 hours; and the annealing temperature of the second stage is 250±10° C., and the annealing time is 3 to 8 hours.

[0020] A high-temperature energy storage meta-aramid dielectric film is prepared using the above-mentioned method for preparing the high-temperature energy storage meta-aramid dielectric film.

[0021] The beneficial effects of the above-mentioned technical invention are as follows: By combining a dynamic deionized water immersion process with a gradient annealing process and introducing a silicon nitride deposition layer, and through the coordinated optimization of specific parameters, this invention overcomes the bottlenecks of impurity residue and molecular chain disorder in traditional meta-aramid films, effectively improving the dielectric properties of meta-aramid films. The invention significantly reduces the leakage current of the film, eliminates insulation weaknesses, and exhibits excellent high-temperature energy storage characteristics. The preparation process of the present invention is simple, low-cost, and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an optical photograph of the mesoaramid dielectric film in Example 1.

[0023] Figure 2 This is a scanning electron microscope photograph of the surface of the intermediate aramid dielectric film in Example 1.

[0024] Figure 3 This is a scanning electron microscope photograph of the cross section of the intermediate aramid dielectric film in Example 1.

[0025] Figure 4 This is the XRD pattern of the meso-aramid dielectric film of Example 1.

[0026] Figure 5 This is a diagram showing the dielectric properties test results of the meso-aramid dielectric film of Example 1.

[0027] Figure 6 This is a diagram showing the breakdown strength test results of the intermediate aramid dielectric film in Example 1.

[0028] Figure 7 This is a graph showing the energy storage performance test results of the meso-aramid dielectric film at 150°C in Example 1. DETAILED DESCRIPTION

[0029] Example 1

[0030] ①Preparation of meta-aramid solution

[0031] 10 g of meta-aramid polymer solution and 10 g of N,N-dimethylacetamide were stirred and mixed uniformly at a stirring rate of 450 rpm, a stirring temperature of 90° C., and a stirring time of 3 h to obtain a meta-aramid solution diluted to 10 wt %;

[0032] ② Preparation of meta-aramid primary film

[0033] The meta-aramid solution was allowed to stand for 6 hours, then defoamed in a vacuum of -0.1 MPa, and then the solution was slowly and evenly coated on a clean glass plate using a coating machine. After the film was formed, it was dried at 80° C. for 12 hours to completely evaporate the solvent, thereby preparing a preformed meta-aramid film;

[0034] ③ Preparation of meta-aramid dielectric film

[0035] The preformed meta-aramid film was immersed in deionized water at 80°C for 4 days to remove impurities, with a dynamic water change frequency of 5 times / day. After drying, it was placed in a magnetron sputtering chamber, with a silicon wafer with a purity greater than 99.9999% as the target material, a mixed gas of argon and ammonia as the working gas, a chamber pressure of 0.3 Pa, a gas flow ratio of argon to ammonia of 1:1, and a sputtering power density of 1.5 W / cm 2 The temperature during the sputtering process of the meta-aramid film was controlled at 175°C, and the thickness of the deposited silicon nitride layer was 10-20 nm. The film was then annealed at 200°C for 1 hour and then at 250°C for 6 hours to produce the meta-aramid dielectric film.

[0036] Depend on Figure 1 、 Figure 2 and Figure 3 As can be seen, the meta-aramid dielectric film prepared in this example exhibits uniform thickness, a smooth, dense surface, and no obvious defects. This is primarily due to the appropriate viscosity of the meta-aramid solution. Furthermore, the coordinated process of high-temperature impurity removal and precise annealing ensures uniform dispersion of the meta-aramid molecular chains. Furthermore, magnetron sputtering technology, at low temperature and low power, creates a thin silicon nitride deposition layer, which enhances the compactness of the molecular chains while minimizing damage to the meta-aramid.

[0037] Depend on Figure 4 It can be seen that the meta-aramid dielectric film has an obvious peak at 23.40°, indicating that the meta-aramid molecular chain has a molecular chain spacing of 0.383 nm.

[0038] Depend on Figure 5 It can be seen that the meta-aramid dielectric film has excellent dielectric properties. At 150°C, the dielectric constant of the film is 4.82 at 1kHz, and as the frequency increases, the dielectric constant remains basically stable; the dielectric loss is always maintained at a low level.

[0039] The breakdown strength test of the meta-aramid dielectric film at 150°C was carried out, and the results are as follows: Figure 5 shown.

[0040] Breakdown strength test method: DC voltage, ramp rate 200V / s, test temperature 150℃, clamp the sample between the rod-plate electrode, immerse the electrode in silicone oil for testing, control the sample to 10-15μm, each film test requires at least 10 sets of valid data, data analysis is based on the formula Where P(E) is the cumulative failure probability; E is the measured breakdown field strength; Eb is the Weibull breakdown strength, which is the field strength when the cumulative failure probability is 63.2%; β is the shape parameter that determines the degree of data dispersion.

[0041] Depend on Figure 6 It can be seen that the breakdown strength of the meta-aramid dielectric film is as high as 480kV / mm. The reason is that the meta-aramid dielectric film can effectively remove chloride ions in the film through the coordinated process of high-temperature impurity removal and precise annealing treatment, and the compactness between molecular chains is improved by adding a silicon nitride deposition layer, thereby greatly improving the breakdown strength of the film.

[0042] The energy storage performance of the meta-aramid dielectric film was tested at 150°C. The results are as follows: Figure 7 The testing instrument is a TF Analyzer 2000E ferroelectric analyzer produced by aixACCT, Germany, with an AC power supply of 100 Hz. Before the measurement, electrodes with a diameter of 4.5 mm are sputtered onto both sides of the film, and the sample thickness is controlled at 10-15 μm.

[0043] Depend on Figure 7 As shown in Figure 2, the energy storage density of the meta-aramid dielectric film is 3.24 J / cm when the energy storage efficiency is greater than 90% at 150°C. 3 , the maximum energy storage density reaches 5.46J / cm 3 The reason for this is that the meta-aramid molecular chains are evenly dispersed, allowing for close packing of the molecular chains during film formation. This effectively removes residual chloride ions in the film, making the film dense and uniform overall, thus achieving higher energy storage performance.

[0044] Comparative Example 1

[0045] Comparative Example 1 Compared with Example 1, the dynamic immersion process was changed to continuous rinsing with deionized water for 3 hours, and the other process steps remained unchanged.

[0046] Comparative Example 2

[0047] Comparative Example 2 Compared with Example 1, the soaking days of the dynamic soaking process were changed to 1 day, and the other process steps remained unchanged.

[0048] Comparative Example 3

[0049] Comparative Example 3 Compared with Example 1, the soaking days of the dynamic soaking process were changed to 2 days, and the other process steps remained unchanged.

[0050] Comparative Example 4

[0051] Comparative Example 4 Compared with Example 1, the soaking days of the dynamic soaking process were changed to 3 days, and the other process steps remained unchanged.

[0052] Comparative Example 5

[0053] Comparative Example 5 Compared with Example 1, the soaking days of the dynamic soaking process were changed to 5 days, and the other process steps remained unchanged.

[0054] Comparative Example 6

[0055] Comparative Example 6 Compared with Example 1, the soaking temperature of the dynamic soaking process was changed to 25°C, the soaking days were changed to 1 day, and the other process steps remained unchanged.

[0056] Comparative Example 7

[0057] Comparative Example 7 Compared with Comparative Example 6, the soaking days of the dynamic soaking process were changed to 3 days, and the other process steps remained unchanged.

[0058] Comparative Example 8

[0059] Comparative Example 8 Compared with Comparative Example 6, the soaking days of the dynamic soaking process were changed to 5 days, and the other process steps remained unchanged.

[0060] Comparative Example 9

[0061] Comparative Example 9 Compared with Comparative Example 6, the soaking days of the dynamic soaking process were changed to 7 days, and the other process steps remained unchanged.

[0062] Comparative Example 10

[0063] Comparative Example 10 Compared with Comparative Example 6, the soaking days of the dynamic soaking process were changed to 9 days, and the other process steps remained unchanged.

[0064] Comparative Example 11

[0065] In Comparative Example 11, compared with Example 1, the step of depositing the silicon nitride layer by magnetron sputtering is eliminated, and the other process steps remain unchanged.

[0066] Comparative Example 12

[0067] Comparative Example 12 Compared with Example 1, the thickness of the silicon nitride deposition layer is controlled to be 50-80 nm, and the other process steps remain unchanged.

[0068] Comparative Example 13

[0069] In Comparative Example 11, compared with Example 1, the gradient annealing step is eliminated, and the other process steps remain unchanged.

[0070] Comparative Example 14

[0071] Comparative Example 14 is relative to Example 1, but adopts a single annealing process, the annealing process is 1 hour at 200° C., and the other process steps remain unchanged.

[0072] Comparative Example 15

[0073] Comparative Example 15 is relative to Example 1, but adopts a single annealing process, wherein the annealing process is performed at 250° C. for 6 hours, and other process steps remain unchanged.

[0074] The energy storage density of the meta-aramid dielectric films prepared in the 15 comparative examples was tested at 150° C. when the energy storage efficiency was greater than 90%, using the same testing method as that of Example 1. The results are as follows.

[0075] Table 1 Energy storage density list

[0076]

[0077]

[0078]

[0079] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0080] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature energy storage meta-aramid dielectric film, characterized in that The following steps are involved: A. mixing a meta-aramid polymer solution and a polar solvent to obtain a meta-aramid solution; B. The meta-aramid solution is allowed to stand and defoamed in vacuum, and then evenly coated on the surface of the plate. After high-temperature drying, the solvent is completely evaporated, and the preformed meta-aramid film is peeled off from the surface of the plate; C. Soaking the preformed meta-aramid film in deionized water to remove impurities; D. Using magnetron sputtering to form a silicon nitride deposition layer on the surface of the meta-aramid film after impurities are removed; E. Annealing the meta-aramid film with the deposited silicon nitride layer.

2. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 1, characterized in that: In step A, the polar solvent is N,N-dimethylacetamide or N-methylpyrrolidone, the mass fraction of the meta-aramid in the meta-aramid solution is 8-10wt%, the mixing speed is 200-800rpm, the mixing temperature is 80-150°C, and the mixing time is 2-12h.

3. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 2, wherein: In step B, the standing time is 6 to 24 hours, the defoaming temperature is room temperature, and the defoaming vacuum degree is -0.1 MPa.

4. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 3, wherein: In step B, the material of the plate is glass, metal or polyimide, and the coating method is spin coating, dip coating, wire rod coating or blade coating.

5. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 4, characterized in that: In step B, the drying method is forced air drying or vacuum drying, and the drying temperature is 60-100°C.

6. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 5, characterized in that: In step C, the deionized water soaking temperature is room temperature to 80° C., the soaking time is 4 to 7 days, and the dynamic water change frequency is 3 to 5 times per day.

7. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 6, characterized in that: In step D, a silicon wafer with a purity greater than 99.9999% is used as the target material, a mixture of argon and ammonia is used as the working gas, the chamber pressure is 0.2-0.5 Pa, the flow rate ratio of argon to ammonia is 1:1-1:2, and the sputtering power density is 1.5-2 W / cm 2 , the temperature during the sputtering process of the meta-aramid film is controlled at 170-180°C, and the thickness of the silicon nitride deposition layer is 10-20nm.

8. The method for preparing a high-temperature energy storage meta-aramid dielectric film according to claim 7, characterized in that: In step E, a two-stage annealing is adopted, wherein the annealing temperature of the first stage is 200±10° C., and the annealing time is 1 to 3 hours; and the annealing temperature of the second stage is 250±10° C., and the annealing time is 3 to 8 hours.

9. A high-temperature energy storage meta-aramid dielectric film, characterized by: The high-temperature energy storage meta-aramid dielectric film is prepared using the preparation method of any one of claims 1 to 8.

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