Poly(4-methyl-1-pentene) composite films and capacitors based on core-shell nanofillers
By preparing ZrO2@Al2O3 core-shell nanofillers and poly-4-methyl-1-pentene composites, a dielectric constant gradient was constructed, which solved the problems of low energy storage density and high-temperature dielectric performance deterioration of PMP films. This resulted in improved breakdown field strength and energy storage density at high temperatures, thus enhancing the performance of film capacitors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ELECTRIC POWER RES INST CHINA SOUTHERN POWER GRID CO LTD
- Filing Date
- 2026-05-25
- Publication Date
- 2026-07-10
AI Technical Summary
Existing PMP films have limited energy storage density, especially in high-temperature environments where their dielectric properties deteriorate. Furthermore, nanocomposite modification suffers from problems such as uneven nanoparticle dispersion, increased losses, and interface defects, leading to the deterioration of composite material performance.
By combining ZrO2@Al2O3 core-shell nanofiller with poly4-methyl-1-pentene, a film was prepared by mixing ZrO2@Al2O3 core-shell nanofiller with poly4-methyl-1-pentene solution to construct a dielectric constant gradient to uniformly disperse nanoparticles, thereby improving breakdown field strength and energy storage density.
The breakdown field strength and energy storage density of the composite film were significantly improved at both room temperature and high temperature, thus enhancing the high-temperature performance and stability of the film capacitor.
Smart Images
Figure CN122356533A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power capacitor technology, and in particular to a poly4-methyl-1-pentene composite film and capacitor based on core-shell nanofillers. Background Technology
[0002] With the increasing demand for electricity, energy storage technology has received widespread attention. Compared with electrochemical capacitors and rechargeable batteries, film capacitors have advantages such as high power density and fast charging and discharging speed. The performance of film capacitors depends on the properties of the capacitor dielectric material. Poly(4-methyl-1-pentene) (PMP) is a non-polar semi-crystalline polymer. Compared with biaxially oriented polypropylene (BOPP), PMP has a higher melting temperature (approximately 233℃) and a lower density (0.84 g / cm³). 3 Compared to polyimide (PI) and polyetherimide (PEI), PMP can dissolve in non-polar organic solutions such as cyclohexane, making it easier to cast into films. PMP also has excellent electrical properties, with a dielectric constant similar to that of polypropylene (PP) (approximately 2.2), while its dielectric loss is 1 to 2 orders of magnitude lower than that of PP.
[0003] However, existing research shows that the energy storage density of PMP films remains limited, especially in high-temperature environments, where the dielectric properties of PMP films still deteriorate, affecting their high-temperature application prospects in power capacitors. Nanocomposite modification is a common polymer modification method aimed at achieving complementary advantages between inorganic and organic materials. Adding inorganic nanoparticles with high dielectric constants to polymers can improve the dielectric constant of composite materials. At the same time, due to the special properties of inorganic nanoparticles (such as charge trapping), nanocomposite modification also has a certain gain effect on the breakdown field strength of composite materials. However, due to the large difference in physicochemical properties between inorganic nanoparticles and PMP films, composite materials are prone to uneven nanoparticle dispersion, increased losses, interface defects, and matrix structure damage, which in turn leads to the deterioration of composite material performance. In existing research, there is still a lack of effective means to improve the energy storage density and high-temperature performance of PMP films through nanocomposite modification. Summary of the Invention
[0004] This invention provides a poly4-methyl-1-pentene composite film based on core-shell nanofillers that has high breakdown field strength and energy storage density at both room temperature and high temperature.
[0005] The poly-4-methyl-1-pentene composite film based on core-shell nanofillers was prepared by the following steps:
[0006] S1, Preparation of ZrO2@Al2O3 core-shell nanofillers;
[0007] S2, the ZrO2@Al2O3 core-shell nanofiller is mixed with poly4-methyl-1-pentene solution in a preset ratio to obtain ZrO2@Al2O3 / PMP solution;
[0008] S3, the ZrO2@Al2O3 / PMP solution is used to prepare a film using a coating machine;
[0009] Specifically, step S1 includes the following steps:
[0010] S11, ZrO2 nanoparticles are dispersed in a solvent to obtain a slurry;
[0011] S12, add methylaluminoxane to the slurry, and stir the slurry in a closed and dry reaction environment to obtain core-shell structured ZrO2@MAO nanoparticles;
[0012] Among them, methylaluminoxane (MAO) is composed of methylaluminum ((CH) 3)3 A complex mixture of oligomers formed by the partial hydrolysis and polymerization of Al and TMA.
[0013] In this step, after the reaction is complete, the reaction solution can be centrifuged to obtain ZrO2@MAO nanoparticles.
[0014] S13, clean the ZrO2@MAO nanoparticles and dry the cleaned ZrO2@MAO nanoparticles in air to obtain ZrO2@Al2O3 core-shell nanofiller.
[0015] Among them, MAO attached to the surface of ZrO2 will undergo a rapid oxidation reaction to generate Al2O3 when exposed to air; after obtaining ZrO2@Al2O3 core-shell nanofiller, it is usually necessary to grind it to obtain uniform nanoparticles.
[0016] Optionally, the solvent is toluene, and the ratio of the ZrO2 nanoparticles to the toluene is 1g:25mL.
[0017] Optionally, the ratio of the methylaluminoxane to the ZrO2 nanoparticles is 8 mL: 1 g.
[0018] Optionally, the ZrO2 nanoparticles have a particle size of 1~100 nm.
[0019] Optionally, in step S13, the ZrO2@MAO nanoparticles are cleaned with anhydrous ethanol.
[0020] Optionally, the poly-4-methyl-1-pentene solution is prepared by the following method:
[0021] Poly(4-methyl-1-pentene) granules were dissolved in cyclohexane under stirring conditions in a constant-temperature oil bath at 70°C.
[0022] Optionally, in the ZrO2@Al2O3 / PMP solution, the mass ratio of the ZrO2@Al2O3 core-shell nanofiller to poly4-methyl-1-pentene is (0.5:99.5) to (2:98), for example, it can be 0.5:99.5, 1:99, 1.5:98.5, 2:98, etc., or other ratios within the numerical range can be selected.
[0023] Optionally, step S3 specifically includes the following steps:
[0024] S31, the ZrO2@Al2O3 / PMP solution is placed in a vacuum oven at a first preset temperature and under negative pressure for a preset time;
[0025] S32, the ZrO2@Al2O3 / PMP solution processed in step S31 is scraped onto the substrate, and the substrate is dried at a first preset temperature for a preset time, and then dried at a second preset temperature for a preset time.
[0026] S33, the substrate is placed in an oven at a third preset temperature for heat treatment;
[0027] S34, Immerse the heat-treated substrate in warm water to separate the film from the substrate;
[0028] S35, place the separated film in an oven at the fourth preset temperature to dry.
[0029] Optionally, the first preset temperature is 35°C, the second preset temperature is 60°C, the third preset temperature is 200°C, and the fourth preset temperature is 80°C.
[0030] Optionally, the preset processing time for step S31 is 20 minutes.
[0031] Optionally, in step S32, the substrate coated with ZrO2@Al2O3 / PMP solution is first dried at a first preset temperature for 3 hours, and then dried at a second preset temperature for 3 hours.
[0032] Optionally, the heat treatment time is 5 minutes.
[0033] Optionally, the drying time in step S35 is 24 hours.
[0034] The present invention also proposes a capacitor, wherein the dielectric material of the capacitor is a poly-4-methyl-1-pentene composite film based on core-shell nanofillers prepared in the present invention.
[0035] The present invention has the following beneficial effects:
[0036] The ZrO2@Al2O3 core-shell nanofiller prepared in this invention uses ZrO2, which has a high dielectric constant and high surface polarity, as the core, and Al2O3, which has a low dielectric constant and low surface polarity, as the shell. The low surface polarity of the Al2O3 shell allows the ZrO2@Al2O3 core-shell nanofiller to be uniformly dispersed in poly4-methyl-1-pentene through a simple process (stirring). Furthermore, this invention constructs a decreasing dielectric constant gradient from the nanoparticles to the polymer matrix (dielectric constant: ZrO2 > Al2O3 > poly4-methyl-1-pentene), minimizing the difference in dielectric constant between the nanoparticles and the polymer matrix. Experimental results show that by adding a specific proportion of ZrO2@Al2O3 core-shell nanofiller, the poly4-methyl-1-pentene composite film not only exhibits higher breakdown field strength and energy density at room temperature compared to pure poly4-methyl-1-pentene film, but also possesses higher breakdown field strength and energy density at high temperatures, effectively improving the high-temperature performance of film capacitors. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0038] Figure 1 A flowchart illustrating the process of preparing a poly-4-methyl-1-pentene composite film based on a core-shell nanofiller, as described in an embodiment of the present invention.
[0039] Figure 2 Weibull plots of DC breakdown field strength at room temperature for pure PMP film and PMP composite films with different proportions of ZrO2@Al2O3 core-shell nanofiller.
[0040] Figure 3 Weibull plots of DC breakdown field strength for pure PMP film and “PMP1” sample at different temperatures (25℃ and 80℃);
[0041] Figure 4 A bar chart comparing the energy storage density of pure PMP films and PMP composite films with different proportions of ZrO2@Al2O3 core-shell nanofillers at room temperature.
[0042] Figure 5 A bar chart comparing the energy storage density of pure PMP film and "PMP1" sample at different temperatures (25℃ and 80℃). Detailed Implementation
[0043] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0044] In this invention, the terms "first," "second," "third," "fourth," etc., are used to distinguish similar objects and should not be construed as describing specific numerical values or implying relative importance. Experimental methods in the embodiments of this invention that do not specify specific conditions are generally performed under conventional conditions or conditions described in the technical manual, or conditions recommended by the equipment manufacturer. Unless otherwise specified, the general equipment, materials, reagents, etc. used in the embodiments of this invention can be obtained commercially.
[0045] The energy storage density of the capacitor dielectric involved in the embodiments of the present invention can be calculated by the following formula:
[0046] ;
[0047] In the formula, U is the energy storage density, and E is the applied electric field. The vacuum permittivity, The relative permittivity is given by the formula. It can be seen that there is a direct and crucial quantitative correlation between the energy storage density of polymer thin film dielectric and its own permittivity and breakdown field strength. An increase in permittivity and breakdown field strength will lead to a significant increase in energy storage density.
[0048] Example 1
[0049] In this embodiment, a poly4-methyl-1-pentene composite film based on core-shell nanofiller was prepared. The composition and mass percentage of the composite film are as follows: ZrO2@Al2O3 core-shell nanofiller accounts for 1 wt%, and poly4-methyl-1-pentene accounts for 99 wt%.
[0050] See Figure 1 The preparation process in this embodiment includes steps S1 to S3:
[0051] S1, Preparation of ZrO2@Al2O3 core-shell nanofillers, specifically including steps S11-S13:
[0052] S11, ZrO2 nanoparticle raw material is ground with an agate mortar and dried in a forced-air drying oven to obtain ZrO2 nanoparticles with the target particle size (1~100nm); 2g of ZrO2 nanoparticles and 50mL of dry toluene are stirred to make a slurry, the slurry is stirred evenly with a magnetic stirrer, and the ZrO2 nanoparticles are further evenly dispersed in toluene with an ultrasonic disperser.
[0053] S12, add 16 mL of methylaluminoxane (MAO) to the slurry and stir magnetically for 2 hours to initially obtain ZrO2@MAO nanoparticles with a core-shell structure. During this process, the reaction environment must be kept sealed and dry.
[0054] S13. After the reaction is complete, the ZrO2@MAO nanoparticles are centrifuged and then washed with anhydrous ethanol. The washing is repeated several times until the surface of the nanoparticles is clean. The cleaned ZrO2@MAO nanoparticles are placed in an oven for drying. During this process, the MAO attached to the surface of ZrO2 is exposed to the air and will quickly undergo an oxidation reaction to generate Al2O3, thus obtaining ZrO2@Al2O3 granules.
[0055] ZrO2@Al2O3 particles were ground using an agate mortar to obtain uniform ZrO2@Al2O3 core-shell nanofillers for later use.
[0056] S2, Weigh 9.9g of poly4-methyl-1-pentene granules and place them in a three-necked flask, and add 150mL of cyclohexane as a solvent. The mixture in the three-necked flask is mechanically stirred under constant temperature oil bath conditions of 70℃. After reacting for 4 hours, a homogeneous poly4-methyl-1-pentene solution is obtained.
[0057] Weigh 0.1g of the ZrO2@Al2O3 core-shell nanofiller prepared in step S1 and slowly add it to a poly4-methyl-1-pentene solution. Maintain a constant temperature oil bath at 70℃ and stir the mixture for 12 hours to obtain a homogeneous ZrO2@Al2O3 / PMP solution.
[0058] S3, prepare a film from ZrO2@Al2O3 / PMP solution using a coating machine, specifically including the following steps:
[0059] S31, Place the ZrO2@Al2O3 / PMP solution prepared in step S2 into a 35℃ vacuum oven, and remove some air to keep the oven under negative pressure for 20 minutes; the purpose of this step is to degas and defoam the ZrO2@Al2O3 / PMP solution to avoid defects such as bubbles and pores in the final film.
[0060] S32, set the temperature of the automatic coating machine to 35℃, pour the solution processed in step S31 onto a flat and clean glass plate, set the scraper height to 20μm, and scrape the film to maintain a consistent thickness; after coating, keep the temperature of the coating machine at 35℃ and dry the sample for 3 hours, then adjust the temperature of the coating machine to 60℃ and continue drying the sample for 3 hours.
[0061] S33, place the glass plate in an oven at 200℃ for 5 minutes for heat treatment.
[0062] S34, Immerse the heat-treated glass plate in warm water for 10 minutes. The film will separate from the glass plate. Collect the film.
[0063] S35. The separated film is placed in an 80℃ oven and dried for 24 hours to obtain a dried poly4-methyl-1-pentene composite film.
[0064] The composite film sample prepared in this embodiment is labeled "PMP1".
[0065] Example 2
[0066] This embodiment prepared a poly(4-methyl-1-pentene) composite film based on core-shell nanofillers. The preparation process was the same as in Example 1, except that the proportion of ZrO2@Al2O3 core-shell nanofillers was 0.5 wt% and the proportion of poly(4-methyl-1-pentene) was 99.5 wt%. The composite film sample prepared in this embodiment was labeled "PMP0.5".
[0067] Example 3
[0068] This embodiment prepared a poly4-methyl-1-pentene composite film based on core-shell nanofillers. The preparation process was the same as in Example 1, except that the proportion of ZrO2@Al2O3 core-shell nanofillers was 1.5 wt% and the proportion of poly4-methyl-1-pentene was 98.5 wt%. The composite film sample prepared in this embodiment was labeled "PMP1.5".
[0069] Example 4
[0070] This embodiment prepared a poly4-methyl-1-pentene composite film based on core-shell nanofillers. The preparation process was the same as in Example 1, except that the proportion of ZrO2@Al2O3 core-shell nanofillers was 2 wt% and the proportion of poly4-methyl-1-pentene was 98 wt%. The composite film sample prepared in this embodiment was labeled "PMP2".
[0071] The ZrO2@Al2O3 core-shell nanofiller prepared in this embodiment uses ZrO2, which has a high dielectric constant and high surface polarity, as the core, and Al2O3, which has a low dielectric constant and low surface polarity, as the shell. The low surface polarity of the Al2O3 shell allows the ZrO2@Al2O3 core-shell nanofiller to be uniformly dispersed in poly4-methyl-1-pentene through a simple process (stirring). Furthermore, this embodiment constructs a decreasing dielectric constant gradient from the nanoparticles to the polymer matrix (dielectric constant: ZrO2 > Al2O3 > poly4-methyl-1-pentene), minimizing the difference in dielectric constant between the nanoparticles and the polymer matrix.
[0072] To verify the beneficial effects achievable by the embodiments of the present invention, DC breakdown field strength tests were conducted on pure PMP films and samples from Examples 1-4 at different temperatures, and the maximum energy storage density of the samples was calculated. The test results are as follows: Figures 2-5 As shown.
[0073] Figure 2 The Weibull plots show the DC breakdown field strength at room temperature (25°C) for pure PMP films and PMP composite films with different proportions of ZrO2@Al2O3 core-shell nanofillers. Figure 2 It can be seen that the doping of ZrO2@Al2O3 core-shell nanofiller significantly improves the breakdown field strength of PMP films at room temperature; among them, the "PMP1" sample with 1wt% doping exhibits the highest breakdown field strength, reaching 705.96kV / mm at a breakdown probability of 63.2%; and the "PMP1" sample has the largest Weibull shape parameter (β) at 18.78, with a more concentrated breakdown field strength, indicating that the film has a uniform microstructure, fewer defects, and higher film reliability.
[0074] Figure 4 This is a bar chart comparing the storage density of pure PMP films and PMP composite films with different proportions of ZrO2@Al2O3 core-shell nanofillers at room temperature. Figure 4 It can be seen that the relative magnitude of the energy storage density of different films is consistent with the breakdown field strength of the films. The doping of ZrO2@Al2O3 core-shell nanofiller significantly improves the energy storage density of PMP films at room temperature, among which the "PMP1" sample with 1wt% doping has the best performance.
[0075] Figure 3 The Weibull plots show the DC breakdown field strength of pure PMP films and the "PMP1" sample at different temperatures (25℃ and 80℃). Figure 3It can be seen that, whether at 25℃ or 80℃, the breakdown field strength of the "PMP1" sample is significantly higher than that of the pure PMP film, and the Weibull shape parameters of the "PMP1" sample are also significantly better than those of the pure PMP film. The difference in breakdown field strength between the "PMP1" sample at 25℃ and 80℃ is small, indicating that compared with the pure PMP film, the "PMP1" sample not only has a greater breakdown field strength at high temperatures, but also has significantly improved stability as a dielectric material when the temperature changes.
[0076] Figure 5 The image shows a histogram comparing the storage density of pure PMP films and the "PMP1" sample at different temperatures (25°C and 80°C). Figure 5 It can be seen that at 80℃, the energy storage density of the "PMP1" sample is significantly higher than that of pure PMP. Furthermore, when the temperature is increased from 25℃ to 80℃, the energy storage density of the "PMP1" sample only decreases by 8.69%, while the energy storage density of the pure PMP film decreases by 17.48%, further verifying the stability of the "PMP1" sample.
[0077] Experimental results show that by adding a specific proportion of ZrO2@Al2O3 core-shell nanofiller, the poly(4-methyl-1-pentene) composite film not only has higher breakdown field strength and energy density than the pure poly(4-methyl-1-pentene) film at room temperature, but also has higher breakdown field strength and energy density at high temperature (e.g., 80°C). Furthermore, the reliability and stability of the composite film as a dielectric material are significantly improved. Therefore, the technical solution of this invention can effectively improve the high-temperature performance of film capacitors.
[0078] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A poly-4-methyl-1-pentene composite film based on core-shell nanofillers, characterized in that, Prepared by the following steps: S1, Preparation of ZrO2@Al2O3 core-shell nanofillers; S2, the ZrO2@Al2O3 core-shell nanofiller is mixed with poly4-methyl-1-pentene solution in a preset ratio to obtain ZrO2@Al2O3 / PMP solution; S3, the ZrO2@Al2O3 / PMP solution is used to prepare a film using a coating machine; Specifically, step S1 includes the following steps: S11, ZrO2 nanoparticles are dispersed in a solvent to obtain a slurry; S12, add methylaluminoxane to the slurry, and stir the slurry in a closed and dry reaction environment to obtain core-shell structured ZrO2@MAO nanoparticles; S13, clean the ZrO2@MAO nanoparticles and dry the cleaned ZrO2@MAO nanoparticles in air to obtain ZrO2@Al2O3 core-shell nanofiller.
2. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, The solvent is toluene, and the ratio of ZrO2 nanoparticles to toluene is 1g:25mL.
3. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, The ratio of methylaluminoxane to ZrO2 nanoparticles is 8 mL: 1 g.
4. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, The ZrO2 nanoparticles have a particle size of 1~100nm.
5. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, In step S13, the ZrO2@MAO nanoparticles are cleaned with anhydrous ethanol.
6. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, The poly-4-methyl-1-pentene solution was prepared by the following method: Poly(4-methyl-1-pentene) granules were dissolved in cyclohexane under stirring conditions in a constant-temperature oil bath at 70°C.
7. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, In the ZrO2@Al2O3 / PMP solution, the mass ratio of the ZrO2@Al2O3 core-shell nanofiller to poly4-methyl-1-pentene is (0.5:99.5) to (2:98).
8. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 1, characterized in that, Step S3 specifically includes the following steps: S31, the ZrO2@Al2O3 / PMP solution is placed in a vacuum oven at a first preset temperature and under negative pressure for a preset time; S32, the ZrO2@Al2O3 / PMP solution processed in step S31 is scraped onto the substrate, and the substrate is dried at a first preset temperature for a preset time, and then dried at a second preset temperature for a preset time. S33, the substrate is placed in an oven at a third preset temperature for heat treatment; S34, Immerse the heat-treated substrate in warm water to separate the film from the substrate; S35, place the separated film in an oven at the fourth preset temperature to dry.
9. The poly-4-methyl-1-pentene composite film based on core-shell nanofillers according to claim 8, characterized in that, The first preset temperature is 35℃, the second preset temperature is 60℃, the third preset temperature is 200℃, and the fourth preset temperature is 80℃.
10. A capacitor comprising a dielectric material, characterized in that, The medium material is the poly4-methyl-1-pentene composite film based on core-shell nanofillers as described in any one of claims 1-9.