A fully-polymeric nanostructured dielectric film with self-assembled nanoscale interfaces and a method of making the same

Abstract

This invention relates to the field of dielectric materials and energy storage materials, specifically to a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film and its preparation method. The composition of the thin film material meets the following requirements: the mass ratio of thermoplastic resin to bismaleimide resin is 95:5-65:35; the amount of catalyst added is 0.05wt%-2wt% of the weight of the bismaleimide resin. The thin film provided by this invention can meet the application requirements at 150℃ and above 600MV / m. The thermoplastic resin component in the film imparts good flexibility, suitable for the winding and stacking processes of thin film capacitors; while the bismaleimide (BMI) nanoscale multi-interface structure effectively blocks charge injection and excitation, significantly reducing leakage current under high temperature and strong electric field conditions, thereby improving its dielectric energy storage performance under high temperature and strong electric field conditions.

Description

Technical Field

[0001] This invention relates to the field of dielectric materials and energy storage materials, specifically to a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film and its preparation method. Background Technology

[0002] Polymer dielectric film capacitors play an irreplaceable role in the electronics and electrical fields due to their advantages such as fast charging and discharging, high power density, excellent voltage withstand performance, self-healing ability, and resistance to chemical corrosion. As electronic devices move towards miniaturization and lightweight design, and the demand for applications in extreme environments increases, higher requirements are placed on the energy storage performance and reliability of polymer dielectrics at high temperatures. Under the influence of an applied electric field, when the ambient temperature approaches the glass transition temperature of the polymer, the leakage current inside the dielectric increases exponentially and is converted into Joule heat, leading to increased conductivity losses. This not only significantly reduces charging and discharging efficiency but also drastically reduces the breakdown field strength, resulting in the failure or damage of electrical equipment. Therefore, polymer dielectric materials suitable for high-temperature environments not only need to possess excellent dielectric properties such as high dielectric constant and low dielectric loss but also must have low conductivity losses and high breakdown field strength to ensure high charging and discharging efficiency and high discharge energy density.

[0003] Currently, high-temperature polymer dielectric materials used in film capacitors are mainly thermoplastic engineering plastics with high glass transition temperatures (Tg), such as polyetherimide (PEI), polyphenylene sulfide (PPS), polyester (PET), and polyetheretherketone (PEEK). Although these materials possess high Tg and can meet mechanical temperature resistance requirements, their dielectric energy storage performance at high temperatures is still unsatisfactory. For example, at 150°C, conductivity loss increases significantly, leading to a substantial decrease in breakdown field strength, charge / discharge efficiency, and energy storage density. Therefore, developing novel polymer dielectric materials with excellent dielectric energy storage performance over a wide temperature range (from room temperature to 150°C) holds significant application potential. Summary of the Invention

[0004] To address the problem of insufficient dielectric energy storage performance of existing polymer dielectrics under high temperature and strong electric fields, the present invention aims to provide a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric film and its preparation method.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] On the one hand, a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film is provided, wherein the composition of the thin film material meets the following requirements:

[0007] The mass ratio of thermoplastic resin to bismaleimide resin is 95:5-65:35; the amount of catalyst added is 0.05wt%-2wt% of the weight of bismaleimide resin.

[0008] The thermoplastic polymer is a thermoplastic material with a high glass transition temperature; the catalyst is an initiator for the chain extension and crosslinking reactions of bismaleimide resin.

[0009] Furthermore, the mass ratio of thermoplastic resin to bismaleimide resin is 85:15-70:30.

[0010] Furthermore, the amount of catalyst added is 0.1wt%-1wt% of the weight of the bismaleimide resin.

[0011] Furthermore, the thermoplastic polymer is polyetherimide, polysulfone, or polycarbonate.

[0012] Furthermore, the bismaleimide resin is bisphenol A type bismaleimide or 4,4'-diphenylmethane bismaleimide.

[0013] Furthermore, the catalyst is bis-tert-butylperoxyisopropylbenzene or bis-tert-butylperoxy.

[0014] On the other hand, a method for preparing an all-polymer nanostructure dielectric thin film with self-assembled nanoscale multi-interfaces is provided, which includes the following steps:

[0015] S1. The thermoplastic polymer and bismaleimide resin are placed in a polar organic solvent and heated to dissolve; a catalyst is added to obtain a slurry of the composition, the solid content of which is 0.1wt%-20wt%.

[0016] S2. After uniformly coating the slurry onto the glass substrate, bake at 60-90℃ for more than 10 hours to allow the solvent to evaporate as much as possible, and obtain an uncured film;

[0017] S3. The glass substrate after solvent evaporation is subjected to a curing reaction at multiple temperatures between 200℃ and 250℃ to obtain a cured film;

[0018] S4. Place the glass substrate with the cured film into deionized water to peel off the film, and dry the peeled film at high temperature to obtain a fully polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0019] Furthermore, in step S1, the solid content of the slurry is 1wt%-2wt%.

[0020] Furthermore, in step S3, the temperature and time for each stage of the curing reaction are as follows: 200℃ for two hours, and 230℃ for six hours.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention provides a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric film that meets application requirements at 150°C and above 600 MV / m. The thermoplastic resin component in the film imparts excellent flexibility, suitable for winding and stacking processes of film capacitors; while the bismaleimide (BMI) nanoscale multi-interface structure effectively blocks charge injection and excitation, significantly reducing leakage current under high temperature and strong electric field conditions, thereby improving its dielectric energy storage performance under high temperature and strong electric field conditions. When used as a film capacitor, it exhibits excellent device performance over a wide temperature range (room temperature to 150°C), suitable for energy storage capacitors, embedded capacitors, and power electronic devices and microelectronic devices such as organic field-effect transistors in high-temperature environments. Attached Figure Description

[0023] Figure 1 The energy density diagrams are for the all-polymer nanostructure dielectric films with self-assembled nanoscale multi-interfaces obtained in Examples 1-3 of this invention.

[0024] Figure 2 The graphs show the changes in dielectric constant and dielectric loss as a function of frequency for the all-polymer nanostructure dielectric films with self-assembled nanoscale multi-interfaces obtained in Examples 1-3 of this invention.

[0025] Figure 3 The graphs show the changes in dielectric constant and dielectric loss as a function of temperature for the all-polymer nanostructure dielectric films with self-assembled nanoscale multi-interfaces obtained in Examples 1-3 of this invention.

[0026] Figure 4 The energy storage density diagrams are for the dielectric thin films obtained in Comparative Examples 1-6 of this invention.

[0027] Figure 5 The graphs show the changes in dielectric constant and dielectric loss of the dielectric thin films obtained in Comparative Examples 1-6 of this invention as a function of frequency.

[0028] Figure 6 The graphs show the changes in dielectric constant and dielectric loss of the dielectric thin films obtained in Comparative Examples 1-3 of this invention as a function of temperature.

[0029] Figure 7 The DE curves of the all-polymer nanostructure dielectric film / PEI dielectric film with self-assembled nanoscale multi-interface obtained in Example 1 and Comparative Example 1 of this invention are shown.

[0030] Figure 8The DE curves of the all-polymer nanostructure dielectric film / PC dielectric film with self-assembled nanoscale multi-interface obtained in Example 2 and Comparative Example 2 of this invention are shown.

[0031] Figure 9 The DE curves of the all-polymer nanostructure dielectric film / PSU dielectric film with self-assembled nanoscale multi-interface obtained in Example 3 and Comparative Example 3 of this invention are shown.

[0032] Figure 10 This is a SEM image of the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces obtained in Example 1 of the present invention.

[0033] Figure 11 This is a SEM image of the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces obtained in Example 2 of the present invention.

[0034] Figure 12 This is a SEM image of the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces obtained in Example 3 of the present invention.

[0035] Figure 13 This is a SEM image of the dielectric thin film obtained in Comparative Example 1 of the present invention.

[0036] Figure 14 This is a SEM image of the dielectric thin film obtained in Comparative Example 2 of the present invention.

[0037] Figure 15 This is a SEM image of the dielectric thin film obtained in Comparative Example 3 of the present invention.

[0038] Figure 16 This is a SEM image of the dielectric thin film obtained in Comparative Example 4 of the present invention.

[0039] Figure 17 This is a SEM image of the dielectric thin film obtained in Comparative Example 5 of the present invention.

[0040] Figure 18 This is a SEM image of the dielectric thin film obtained in Comparative Example 6 of the present invention.

[0041] Figure 19 This is a SEM image of the dielectric thin film obtained in Comparative Example 7 of the present invention. Detailed Implementation

[0042] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0043] The all-polymer nanostructure dielectric films with self-assembled nanoscale multi-interfaces in Examples 1-3 of this invention comprise the following components:

[0044] (1) Thermoplastic polymers impart film-forming properties to uncured films (B-stage films), toughness to self-assembled nanoscale multi-interface polymer films after curing, as well as basic dielectric properties and high-temperature energy storage properties. The thermoplastic polymers are selected from thermoplastic polymers with high glass transition temperatures, such as polyetherimide (PEI), polysulfone (PSU), and polycarbonate (PC).

[0045] (2) Bismaleimide (BMI) resin. After curing and crosslinking, BMI resin imparts a self-assembled nanoscale multi-interface structure to the film (C-stage Film), thereby giving the film excellent high-temperature energy storage performance. BMI is selected from either bisphenol A type bismaleimide (BPA) or 4,4'-diphenylmethane bismaleimide (BDM).

[0046] (3) Catalyst: The catalyst is an initiator for the chain extension and cross-linking reactions of BMI, which can lower the reaction temperature and increase the reaction rate. The catalyst is selected from free radical initiators with a half-life of 1 min / ℃ higher than the melting point of BMI (around 180℃), such as bis(tert-butylperoxyisopropylbenzene) (BIPB) and di-tert-butylperoxy (DTPB).

[0047] (4) The content relationship between each component is as follows: the mass ratio of thermoplastic resin to bismaleimide resin is 95:5-65:35, preferably 90:10-70:30; the amount of catalyst added is 0.05wt%-2wt% of the weight of BMI, preferably 0.1wt%-1wt%.

[0048] Example 1: The raw materials involved in this example include PEI, BPA, and BIPB.

[0049] The preparation steps are as follows:

[0050] 1. Mix polyetherimide (PEI) and bisphenol A type bismaleimide (BPA) in a mass ratio of 75:25, and add 1 wt% (relative to BPABMI) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.15 g of polyetherimide (PEI), 0.05 g of bisphenol A type bismaleimide (BPA), and 0.0005 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0051] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0052] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0053] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0054] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0055] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0056] Implementation Results: The PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment has a storage density as shown in the figure. Figure 1 As shown, it exhibits high energy storage density and efficiency at 150℃, and maintains a charge / discharge efficiency of 91.9% and a discharge energy density of 6.76 J / cm² at an electric field strength of 650 MV / m. 3 The dielectric constant and dielectric loss of the PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment vary with frequency as follows: Figure 2As shown, at a frequency of 1 MHz, the dielectric constant is 3.39 and the dielectric loss is 0.01, indicating that this composition exhibits both high dielectric constant and low dielectric loss. The dielectric constant and dielectric loss of the PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example as a function of temperature are shown below. Figure 3 As shown, this composition exhibits stable dielectric constant and dielectric loss from room temperature to 200°C. The DE curve of the PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example is shown below. Figure 7 As shown, the finer DE rings indicate that the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces possesses high energy storage efficiency. The SEM image of the PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces prepared in this embodiment is shown below. Figure 10 As shown, the spherical phase domains formed by BPA have a small particle size and good compatibility with the PEI matrix.

[0057] Example 2: The raw materials involved in this example include PC, BPA, and BIPB.

[0058] The preparation steps are as follows:

[0059] 1. Mix polycarbonate (PC) and bisphenol A type bismaleimide (BPA) in a mass ratio of 75:25, and add 1 wt% (relative to BPA) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.15 g of polycarbonate (PC), 0.05 g of bisphenol A type bismaleimide (BPA), and 0.0005 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0060] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0061] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0062] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0063] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0064] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PC / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0065] Implementation Results: The storage density of the PC / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment is as follows: Figure 1 As shown, it exhibits high energy storage density and efficiency at 150℃, and maintains a charge / discharge efficiency of 90.8% and a discharge energy density of 6.14 J / cm² at an electric field strength of 600 MV / m. 3 The dielectric constant and dielectric loss of the PC / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment vary with frequency as follows: Figure 2 As shown, at a frequency of 1 MHz, the dielectric constant is 2.86 and the dielectric loss is 0.007, indicating that this composition exhibits both high dielectric constant and low dielectric loss. The dielectric constant and dielectric loss of the PEI / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example as a function of temperature are shown below. Figure 3 As shown, this composition exhibits stable dielectric constant and dielectric loss from room temperature to 200°C. The DE curve of the PC / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example is shown below. Figure 8 As shown, the finer DE rings indicate that the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces possesses high energy storage efficiency. The SEM image of the PC / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces prepared in this embodiment is shown below. Figure 11 As shown, the spherical phase domains formed by BPA have a small particle size and good compatibility with the PC matrix.

[0066] Example 3: The raw materials involved in this example include PSU, BPA, and BIPB.

[0067] The preparation steps are as follows:

[0068] 1. Mix polysulfone (PSU) and bisphenol A type bismaleimide (BPA) in a mass ratio of 75:25, and add 1 wt% (relative to BPA) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.15 g of polysulfone (PSU), 0.05 g of bisphenol A type bismaleimide (BPA), and 0.0005 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0069] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0070] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0071] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0072] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0073] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0074] Implementation Results: The energy storage density of the PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment is as follows: Figure 1 As shown, it exhibits high energy storage density and efficiency at 150℃, and maintains a charge / discharge efficiency of 90.1% and a discharge energy density of 4.89 J / cm² at an electric field strength of 550 MV / m. 3 The dielectric constant and dielectric loss of the PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this embodiment vary with frequency as follows: Figure 2As shown, at a frequency of 1 MHz, the dielectric constant is 3.06 and the dielectric loss is 0.009, indicating that this composition exhibits both high dielectric constant and low dielectric loss. The dielectric constant and dielectric loss of the PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example as a function of temperature are shown below. Figure 3 As shown, this composition exhibits stable dielectric constant and dielectric loss from room temperature to 200°C. The DE curve of the PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this example is shown below. Figure 9 As shown, the finer DE rings indicate that the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces possesses high energy storage efficiency. The SEM image of the PSU / BPA (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces prepared in this embodiment is shown below. Figure 11 As shown, the spherical phase domains formed by BPA have a small particle size and good compatibility with the PSU matrix.

[0075] Comparative Example 1: The raw materials involved in this comparative example include PEI.

[0076] 1. Weigh 0.2g of polyetherimide (PEI) and add 10ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0077] 2. Place the glass bottle containing the film-forming solution on a magnetic stirrer heated to 50°C and stir for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0078] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0079] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0080] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0081] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain the PEI dielectric film.

[0082] Comparative Results: The energy storage density of the PEI dielectric thin film prepared in this comparative example is as follows: Figure 4 As shown, it exhibits low energy storage density and efficiency at 150℃, with a charge / discharge efficiency of only 72.4% and a discharge energy density of 5.28 J / cm² at an electric field strength of 600 MV / m. 3 The dielectric constant and dielectric loss of the dielectric thin film prepared in this comparative example change with frequency as follows: Figure 5 As shown, at a frequency of 1 MHz, the dielectric constant is 3.29 and the dielectric loss is 0.0066. The dielectric constant and dielectric loss of the dielectric film prepared in this comparative example change with temperature as follows: Figure 6 As shown. The DE curve of the dielectric thin film prepared in this comparative example is shown. Figure 7 As shown, the coarser DE rings indicate that the dielectric film has low energy storage efficiency. The SEM image of the PEI dielectric film prepared in this comparative example is shown below. Figure 13 As shown.

[0083] Comparative Example 2: The raw materials involved in this comparative example include PC.

[0084] 1. Weigh 0.2g of polycarbonate (PC) and add 10ml of N,N-dimethylformamide (DMF) to prepare a solution.

[0085] 2. Place the glass bottle containing the film-forming solution on a magnetic stirrer heated to 50°C and stir for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0086] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0087] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and bake at 150°C for 10 hours. After natural cooling, the cured film is obtained.

[0088] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0089] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PC dielectric film.

[0090] Comparative Results: The energy storage density of the PC dielectric thin film prepared in this comparative example is as follows: Figure 4 As shown, it exhibits low energy storage density and efficiency at 150℃, with a charge / discharge efficiency of only 73.5% and a discharge energy density of 2.32 J / cm² at an electric field strength of 450 MV / m. 3The dielectric constant and dielectric loss of the dielectric thin film prepared in this comparative example change with frequency as follows: Figure 5 As shown, at a frequency of 1 MHz, the dielectric constant is 3.00 and the dielectric loss is 0.009. The dielectric constant and dielectric loss of the dielectric thin film prepared in this comparative example change with temperature as follows: Figure 6 As shown. The DE curve of the dielectric thin film prepared in this comparative example is shown. Figure 8 As shown, the coarser DE rings indicate that the dielectric film has low energy storage efficiency. The SEM image of the PC dielectric film prepared in this comparative example is shown below. Figure 14 As shown.

[0091] Comparative Example 3: The raw materials involved in this comparative example include PSU.

[0092] 1. Weigh 0.2g of polysulfone (PSU) and add 10ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0093] 2. Place the glass bottle containing the film-forming solution on a magnetic stirrer heated to 50°C and stir for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0094] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0095] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0096] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0097] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain the PSU dielectric film.

[0098] Comparative Results: The energy storage density of the PSU dielectric thin film prepared in this comparative example is as follows: Figure 4 As shown, it exhibits low energy storage density and efficiency at 150℃. At an electric field strength of 550 MV / m, the charge / discharge efficiency is only 77.5%, and the discharge energy density is 4.99 J / cm². 3 The dielectric constant and dielectric loss of the dielectric thin film prepared in this comparative example change with frequency as follows: Figure 5As shown, at a frequency of 1 MHz, the dielectric constant is 3.02 and the dielectric loss is 0.007. The dielectric constant and dielectric loss of the dielectric thin film prepared in this comparative example change with temperature as follows: Figure 6 As shown. The DE curve of the dielectric thin film prepared in this comparative example is shown. Figure 9 As shown, the coarser DE rings indicate that the dielectric film has low energy storage efficiency. The SEM image of the PSU dielectric film prepared in this comparative example is shown below. Figure 15 As shown.

[0099] Comparative Example 4: The raw materials involved in this comparative example include PEI, BPA, and BIPB.

[0100] The preparation steps are as follows:

[0101] 1. Mix polyetherimide (PEI) and bisphenol A type bismaleimide (BPA) at a mass ratio of 90:10, and add 1 wt% (relative to BPA) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.18 g of polyetherimide (PEI), 0.02 g of bisphenol A type bismaleimide (BPA), and 0.0002 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0102] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0103] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0104] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0105] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0106] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PEI / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0107] Results: The energy density of the PEI / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is as follows: Figure 4 As shown, at 150℃ and an electric field strength of 600MV / m, the charge-discharge efficiency is 87.7%, and the discharge energy density is 5.42J / cm². 3 The dielectric constant and dielectric loss of the PEI / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example vary with frequency as follows: Figure 5 As shown, at a frequency of 1 MHz, the dielectric constant is 3.42 and the dielectric loss is 0.01. The SEM image of the PEI / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is shown below. Figure 16 As shown.

[0108] Comparative Example 5: The raw materials involved in this comparative example include PC, BPA, and BIPB.

[0109] The preparation steps are as follows:

[0110] 1. Mix polycarbonate (PC) and bisphenol A type bismaleimide (BPA) in a mass ratio of 90:10, and add 1 wt% (relative to BPA) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.18 g of polyetherimide (PEI), 0.02 g of bisphenol A type bismaleimide (BPA), and 0.0002 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0111] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0112] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0113] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0114] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0115] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PC / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0116] Results: The energy density of the PC / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is as follows: Figure 4 As shown, at 150℃ and an electric field strength of 600 MV / m, the charge-discharge efficiency is 72.9%, and the discharge energy density is 4.70 J / cm². 3 The dielectric constant and dielectric loss of the PC / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example vary with frequency as follows: Figure 5 As shown, at a frequency of 1 MHz, the dielectric constant is 2.73 and the dielectric loss is 0.007. The SEM image of the PC / BPA (90 / 10) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is shown below. Figure 17 As shown.

[0117] Comparative Example 6: The raw materials involved in this comparative example include PEI, BDM, and BIPB.

[0118] The preparation steps are as follows:

[0119] 1. Mix polyetherimide (PEI) and 4,4'-diphenylmethane bismaleimide (BDM) in a mass ratio of 75:25, and add 1 wt% (relative to BDM) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.15 g of polyetherimide (PEI), 0.05 g of 4,4'-diphenylmethane bismaleimide (BDM), and 0.0005 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0120] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0121] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0122] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 200℃ for two hours, 230℃ for six hours, and the cured film is obtained after natural cooling.

[0123] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0124] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PEI / BDM (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface.

[0125] Results: The energy density of the PEI / BDM (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is as follows: Figure 4 As shown, it exhibits high energy storage density and efficiency at 150℃, with a charge / discharge efficiency of 83.2% and a discharge energy density of 6.4 J / cm² at an electric field strength of 600 MV / m. 3 The dielectric constant and dielectric loss of the PEI / BDM (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example vary with frequency as follows: Figure 5 As shown, at a frequency of 1 MHz, the dielectric constant is 2.98 and the dielectric loss is 0.008. The SEM image of the PEI / BDM (75 / 25) all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interface structure prepared in this comparative example is shown below. Figure 18 As shown, the phase domains formed by BDM have a large particle size and poor compatibility with the PEI matrix.

[0126] Comparative Example 7: The raw materials involved in this comparative example include PEI, BPA, and BIPB.

[0127] The preparation steps are as follows:

[0128] 1. Mix polyetherimide (PEI) and bisphenol A type bismaleimide (BPA) in a mass ratio of 75:25, and add 1 wt% (relative to BPABMI) of bis(tert-butylperoxyisopropylbenzene) radical initiator to prepare a 2 wt% solution. For example, weigh 0.15 g of polyetherimide (PEI), 0.05 g of bisphenol A type bismaleimide (BPA), and 0.0005 g of bis(tert-butylperoxyisopropylbenzene) (BIPB), and add 10 ml of N-methylpyrrolidone (NMP) to prepare a solution.

[0129] 2. Heat the above solution to 50°C under magnetic stirring and dissolve and disperse for 8 hours to ensure that the solute is fully and uniformly dissolved in the solvent.

[0130] 3. Clean the glass slide thoroughly to avoid dust contamination. Then, preheat the glass slide in a 70°C oven for half an hour. Next, use a dropper to draw 5ml of film-forming solution onto the glass slide and bake it in a 70°C oven for 10 hours to allow the solvent to evaporate.

[0131] 4. Place the glass slide after the solvent has evaporated into a vacuum oven and adjust the temperature to carry out a multi-stage curing reaction. The temperature and time for each stage are as follows: 160℃ for two hours, 200℃ for two hours, and 230℃ for six hours. After natural cooling, the cured film is obtained.

[0132] 5. Immerse the glass slide with the cured film in deionized water. After a period of time, the film will detach from the glass slide on its own. Wrap the detached film with aluminum foil.

[0133] 6. Place the aluminum foil wrapped with the film into a vacuum oven and dry it at 120°C for 10 hours to obtain a PEI / BPA (75 / 25) dielectric film.

[0134] Implementation results: The microstructure of the PEI / BPA (75 / 25) prepared in this comparative example is as follows: Figure 19 As shown, the film prepared by this composition and process forms a homogeneous structure rather than a nanostructure. This phenomenon is due to the fact that the process first involves curing at 160°C for 2 hours, a curing temperature lower than the glass transition temperature of the thermoplastic polymer matrix PEI and the melting point of BPA. Therefore, during the curing and crosslinking of BPA molecules, the aggregation of BMI molecular chains is restricted, thereby inhibiting phase separation.

[0135] In summary, the all-polymer nanostructure dielectric film with self-assembled nanoscale multi-interfaces prepared by this invention can withstand high temperatures up to 250°C; in particular, it exhibits excellent high-temperature dielectric energy storage performance, demonstrating superior energy storage performance at temperatures above 150°C and 600 MV / m and under strong electric fields, such as high breakdown field strength (Eb≥600MV / m), high charge / discharge efficiency (η≥90%), and high discharge energy density (Ue≥5J / cm). 3 Moreover, the preparation method is simple, the raw material cost is low, and it is easy to achieve mass production, which has important industrialization prospects.

[0136] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0137] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film, characterized in that, The composition of the thin film material must meet the following requirements: The mass ratio of thermoplastic resin to bismaleimide resin is 85:15-70:30; the amount of catalyst added is 0.05 wt%-2 wt% of the weight of bismaleimide resin. The thermoplastic resin is polyetherimide, polysulfone, or polycarbonate; the bismaleimide resin is bisphenol A type bismaleimide; the catalyst is an initiator that reacts with the bismaleimide resin to carry out chain extension and crosslinking reactions. The thin film preparation method includes the following steps: S1. The thermoplastic polymer and bismaleimide resin are placed in a polar organic solvent and heated to dissolve; a catalyst is added to obtain a slurry of the composition, the solid content of which is 0.1 wt%-20 wt%. S2. After uniformly coating the slurry onto the glass substrate, bake it to allow the solvent to evaporate as much as possible, resulting in an uncured film; S3. The glass substrate after solvent evaporation is subjected to a curing reaction at multiple temperatures between 200℃ and 250℃ to obtain a cured film; S4. Place the glass substrate with the cured film into deionized water to peel off the film, and dry the peeled film at high temperature to obtain a fully polymer nanostructure dielectric film with self-assembled nanoscale multi-interface. In step S3, the temperature and time for each stage of the curing reaction are as follows: 200 ℃ for two hours, and 230 ℃ for six hours.

2. The method for preparing a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film according to claim 1, characterized in that, The amount of catalyst added is 0.1 wt%-1 wt% of the weight of the bismaleimide resin.

3. The method for preparing a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film according to claim 1, characterized in that, The catalyst is bis-tert-butylperoxyisopropylbenzene or di-tert-butylperoxy.

4. The method for preparing a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film according to claim 1, characterized in that, In step S1, the solid content of the slurry is 1 wt%-2 wt%.

5. The method for preparing a self-assembled nanoscale multi-interface all-polymer nanostructure dielectric thin film according to claim 1, characterized in that, In step S2, bake at 60-90℃ for more than 10 hours.

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