PEI-based multilayer dielectric composite film containing inorganic interlayer as well as preparation method and application of PEI-based multilayer dielectric composite film
By alternately stacking sodium bismuth titanate nanofiber layers in a polyetherimide film, a multilayer dielectric composite film was prepared, which solved the problems of low energy storage density and dielectric loss, and achieved high-performance dielectric properties, making it suitable for applications such as dielectric capacitors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-03-13
AI Technical Summary
Existing polymer-based nanocomposite films suffer from problems such as low energy storage density and high dielectric loss in terms of dielectric properties. Furthermore, the microscopic local aggregation and orientation of inorganic fillers are difficult to control, leading to a degradation in macroscopic performance.
A PEI-based multilayer dielectric composite film with inorganic interlayers was prepared by alternately stacking sodium bismuth titanate nanofibers with high dielectric constant and polyetherimide (PEI) films through casting and heat treatment. The orientation of the sodium bismuth titanate nanofiber filler was strictly controlled to be perpendicular to the direction of electric field application.
A multilayer dielectric composite film with high dielectric constant, high breakdown field strength and low dielectric loss, high energy storage density and high energy storage efficiency has been achieved, which is suitable for dielectric capacitors and other fields.
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Figure CN121650320A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer energy storage technology, specifically relating to a polyetherimide (PEI) based multilayer dielectric composite film with inorganic interlayer, its preparation method and application. Background Technology
[0002] With the rapid development of modern science and technology, the field of power electronics systems urgently needs dielectric materials with superior performance. Dielectric capacitors, due to their fast charging and discharging speeds and ultra-high power densities, have wide applications and promising prospects in fields such as hybrid electric vehicles, 5G communications, and pulsed power devices. Microelectronic devices, including gate dielectrics, high-energy-density capacitors, and electroactive materials, all require nanocomposite films to possess high dielectric constants and dielectric strength while still exhibiting low dielectric loss, high breakdown field strength, and good toughness. However, the relatively low energy density of dielectrics makes them unable to meet the miniaturization and lightweight requirements of advanced electronic devices. Therefore, the development of dielectric materials with high energy density and low dielectric loss is urgently needed. Traditional polymer materials such as polyimide (PI), polymethyl methacrylate (PMMA), and epoxy resins have the characteristics of small size and easy processing, but their low dielectric constants make them difficult to meet practical application requirements.
[0003] To further improve the dielectric energy storage capacity of polymers, inorganic filler integration has been selected as an effective approach, thereby optimizing the performance of polymer-based nanocomposite films. On the one hand, the properties of inorganic fillers can be utilized to specifically enhance energy storage capabilities; on the other hand, the polymer matrix retains its fundamental properties, thus providing support for improved energy storage performance. Currently, the application of inorganic fillers in polymer-based composite films has been explored to some extent. However, researchers have found that although inorganic filler integration can play a positive role, the microscopic local aggregation and orientation of inorganic fillers are difficult to control, leading to a degradation in the macroscopic performance of the composite film. Therefore, there is an urgent need to develop high-performance polymer-based dielectric materials that balance multiple properties. Summary of the Invention
[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a PEI-based multilayer dielectric composite film with an inorganic interlayer, its preparation method, and its applications. By physically blending inorganic nanofibers with high dielectric constants with a rapidly volatile solvent and then directly casting the mixture, a ceramic fiber layer is prepared as the inorganic interlayer, thus solving the problem of low energy density in composite films prepared by blending inorganic fillers with polymers. The PEI-based multilayer dielectric composite film with an inorganic interlayer prepared by the present invention exhibits high breakdown field strength and high energy density, can be rapidly charged and discharged, and possesses excellent cycle stability.
[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a PEI-based multilayer dielectric composite film with an inorganic interlayer, comprising a first layer, a second layer and a third layer stacked sequentially, wherein the first layer and the third layer are polyetherimide (PEI) films, and the second layer is a ceramic fiber layer composed of sodium bismuth titanate nanofibers (NBTNFs).
[0006] Preferably, the thickness of the first layer and the third layer is 5~6 μm, the thickness of the second layer is 0.3~0.6 μm, and the overall film thickness is 13~14 μm.
[0007] Preferably, the volume fraction of NBTNFs in the composite film is 0.36%~1.26%. By controlling the volume fraction of NBTNFs in the second layer of the PEI-based multilayer dielectric composite film, the dielectric constant and energy storage density of the PEI-based multilayer dielectric composite film can be controlled, resulting in a series of PEI-based multilayer dielectric composite films with excellent energy storage performance. When the amount of NBTNFs introduced in the second layer is 0.99 vol% of the total PEI-based multilayer dielectric composite film, the optimal comprehensive energy storage characteristics are obtained, with a breakdown electric field strength of 620 MV·m. -1 At that time, the energy storage density was 20.87 J·cm³. -3 The energy storage efficiency is 96.47%.
[0008] Preferably, the energy storage density of the PEI-based multilayer dielectric composite film containing the inorganic interlayer is 12.12~20.87 J·cm⁻¹. -3 The energy storage efficiency is 95.21~96.47%.
[0009] Secondly, the present invention provides a method for preparing the PEI-based multilayer dielectric composite film containing an inorganic interlayer, comprising: S1, PEI is dispersed in the first solvent to obtain solution A; sodium bismuth titanate nanofibers are dispersed in the second solvent to obtain suspension X; S2, solution A is first cast on the substrate, dried to form a film, forming the first layer; suspension X is second cast on the first layer, dried to form a film, forming the second layer; solution A is third cast on the second layer, dried to form a film, forming the third layer; the resulting sample is dried to obtain the preliminary sample; S3. The preliminary sample is quenched to obtain a PEI-based multilayer dielectric composite film with inorganic interlayer.
[0010] Preferably, in S1, the first solvent is N. methyl 2 Pyrrolidone.
[0011] Preferably, in S1, the second solvent is isopropanol.
[0012] Preferably, in S1, the sodium bismuth titanate nanofibers are dispersed in a second solvent to obtain a suspension X. Specifically, the sodium bismuth titanate nanofibers are added to the second solvent, and the mixture is alternately stirred and sonicated several times to obtain the suspension X.
[0013] Preferably, S2 specifically involves: casting solution A onto a substrate for the first time, then vacuum drying at 85-125 °C for 35-45 min to form a film, thus forming the first layer; then casting suspension X onto the first layer for the second time, then vacuum drying at 75-95 °C for 25-35 min to form a film, thus forming the second layer; then casting solution A onto the second layer for the third time, then vacuum drying at 85-125 °C for 35-45 min to form a film, thus forming the third layer; and finally vacuum drying the resulting sample at 55-75 °C for 10-14 h to obtain a preliminary sample.
[0014] Preferably, S3 specifically involves heating the preliminary sample at 195~205 ℃ for 8~10 min and then quenching it in ice water at -3~4 ℃ to obtain a PEI-based multilayer dielectric composite film containing an inorganic interlayer.
[0015] Thirdly, the present invention provides the application of the PEI-based multilayer dielectric composite film containing inorganic interlayer in dielectric capacitors.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention selects high dielectric constant ( ε r NBTNFs with high energy storage efficiency η PEI-based multilayer dielectric composite films with inorganic interlayers were designed; the outer layer is a pure PEI film, providing high dielectric strength for the PEI-based multilayer dielectric composite films. η The value is guaranteed, and a high breakdown field strength is ensured. E b The intermediate layer is a ceramic fiber layer composed of NBTNFs as an inorganic interlayer. The high intrinsic dielectric constant of NBTNFs and the microscopic interfacial polarization present in the contact region between NBTNFs and PEI jointly enhance the composite film. ε r This multilayer structure effectively combines the advantages of each layer and strictly controls the orientation of the sodium bismuth titanate nanofiber filler perpendicular to the direction of the electric field, thus achieving high dielectric constant, high breakdown field strength, and low dielectric loss. It also exhibits high energy storage density and high energy storage efficiency, making it suitable for a variety of applications.
[0017] This invention prepares composite films by casting and heat treatment of the films, including quenching in ice water, which improves the ferroelectricity of the films and reduces leakage current. The resulting PEI-based multilayer dielectric composite film has a smooth surface without obvious cracks, and the first and third layers are perfectly connected. The entire film is dense and compact, without obvious pores or defects. The preparation process of this invention is simple and stable, and suitable for industrial production.
[0018] Furthermore, during the preparation of suspension X, alternating stirring and sonication can ensure thorough mixing of components, uniform distribution of raw materials, and reduce the occurrence of defects. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the examples of the present invention or the prior art, the drawings used in the description of the examples or the prior art will be briefly introduced below. Obviously, the drawings described below are some examples of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] Figure 1 This is a SEM image of the top surface of the inorganic interlayer (i.e., the surface of the inorganic interlayer opposite to the outer PEI film) in the PEI-based multilayer dielectric composite thin film material containing the inorganic interlayer prepared in Example 1 of the present invention.
[0021] Figure 2 This is a cross-sectional SEM image of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 1 of the present invention.
[0022] Figure 3 The thermogravimetric curve of NBTNF content in the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 1 of the present invention is compared with the thermogravimetric curve of NBTNF content in the single-layer pure PEI film material prepared in Comparative Example 1.
[0023] Figure 4 The graph shows the dielectric constant of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 1 of this invention as a function of frequency.
[0024] Figure 5 The graph shows the dielectric loss of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 1 of this invention as a function of frequency.
[0025] Figure 6 Hysteresis loop diagram of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 1 of the present invention (test frequency is 100Hz).
[0026] Figure 7This is a SEM image of the top surface of the inorganic interlayer in the PEI-based multilayer dielectric composite thin film material containing the inorganic interlayer prepared in Example 2 of the present invention.
[0027] Figure 8 This is a cross-sectional SEM image of the PEI-based multilayer dielectric composite thin film material containing inorganic interlayers prepared in Example 2 of the present invention.
[0028] Figure 9 The thermogravimetric curve of NBTNF content in the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 2 of the present invention is compared with the thermogravimetric curve of NBTNF content in the single-layer pure PEI film material prepared in Comparative Example 1.
[0029] Figure 10 The graph shows the dielectric constant of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 2 of this invention as a function of frequency.
[0030] Figure 11 The graph shows the dielectric loss of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 2 of this invention as a function of frequency.
[0031] Figure 12 Hysteresis loop diagram of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 2 of the present invention (test frequency is 100Hz).
[0032] Figure 13 This is a SEM image of the top surface of the inorganic interlayer in the PEI-based multilayer dielectric composite thin film material containing the inorganic interlayer prepared in Example 3 of the present invention.
[0033] Figure 14 This is a cross-sectional SEM image of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 3 of the present invention.
[0034] Figure 15 The thermogravimetric curve of NBTNF content in the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 3 of the present invention is compared with the thermogravimetric curve of NBTNF content in the single-layer pure PEI film material prepared in Comparative Example 1.
[0035] Figure 16 The graph shows the dielectric constant of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 3 of this invention as a function of frequency.
[0036] Figure 17 The graph shows the dielectric loss of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 3 of this invention as a function of frequency.
[0037] Figure 18Hysteresis loop diagram of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 3 of the present invention (test frequency is 100Hz).
[0038] Figure 19 This is a SEM image of the top surface of the inorganic interlayer in the PEI-based multilayer dielectric composite thin film material containing the inorganic interlayer prepared in Example 4 of the present invention.
[0039] Figure 20 This is a cross-sectional SEM image of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 4 of the present invention.
[0040] Figure 21 This is a comparison chart of the thermogravimetric curves of NBTNF content in the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 4 of the present invention and the thermogravimetric curves of NBTNF content in the single-layer pure PEI film material prepared in Comparative Example 1.
[0041] Figure 22 The graph shows the dielectric constant of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer obtained in Example 4 of this invention as a function of frequency.
[0042] Figure 23 The graph shows the dielectric loss of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 4 of this invention as a function of frequency.
[0043] Figure 24 Hysteresis loop diagram of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 4 of the present invention (test frequency is 100Hz).
[0044] Figure 25 The hysteresis loop of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 3 of the present invention is compared with the hysteresis loop of the single-layer pure PEI film material prepared in Comparative Example 1 and the composite material prepared in Comparative Example 2 in which NBTNFs are uniformly distributed in PEI after physical blending with PEI (test frequency is 10 Hz). Detailed Implementation
[0045] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0046] It should be noted that the process equipment or apparatus not specifically mentioned in the following examples all use conventional equipment or apparatus in this field.
[0047] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.
[0048] The performance testing method used in this invention is as follows: The prepared multilayer PEI-based multilayer dielectric composite film was cut into a rectangle of 10 mm × 15 mm, then a diffracted film was made, a gold electrode with a diameter of 6 mm was deposited, and then its dielectric properties were tested at room temperature. The prepared multilayer PEI-based multilayer dielectric composite film was cut into 10 mm × 15 mm rectangles, then fabricated into a diffracted film. A 2 mm diameter gold electrode was deposited, and its ferroelectric properties were tested at 10 Hz at room temperature. Energy storage characteristics were calculated, and the energy density was determined. W 1) and energy loss density ( W The calculation formula for 2) is: II III in, W 1 and W 2 represents energy storage density and energy loss density, respectively. P max Indicates the maximum polarization intensity. P r Indicates the remanent polarization intensity. E Indicates electric field strength. P This indicates the polarization intensity.
[0049] The present invention will now be described in further detail with reference to the accompanying drawings.
[0050] Example 1 This example demonstrates the preparation of a set of PEI-based multilayer dielectric composite films containing inorganic interlayers using a solution-layer casting process. The PEI-based multilayer dielectric composite film can be simplified to a 0-X-0 model, where 0 represents the first and third layers, and X represents the volume fraction of NBTNFs in the second layer of the prepared composite film. In this example, the PEI-based multilayer dielectric composite film can be simplified to a 0-0.36-0 model, where the first and third layers are pure polyetherimide (PEI) films, and the second layer is a ceramic fiber layer with NBTNFs comprising 0.36% of the volume of the prepared composite film.
[0051] The above-mentioned method for preparing PEI-based multilayer dielectric composite films containing inorganic interlayers includes the following steps: (1) Measure 10 mL of isopropanol as a solvent and add it to a beaker containing the rotor. Weigh 0.025 g of NBTNFs powder, making it account for 0.36% of the volume of the prepared composite film, and mix it with the measured isopropanol.
[0052] (2) Seal the solution obtained in step (1) with plastic wrap and place it on a magnetic stirrer at 500 r / min. -1 Preliminary dispersion was achieved by stirring at room temperature for 6 hours at a certain speed. The initially dispersed suspension was then sonicated for 30 minutes, followed by stirring for another 1 hour. This alternating sonication and stirring process was repeated three times to obtain a homogeneous suspension X in which NBTNFs were stably dispersed in isopropanol. 0.36 .
[0053] (3) Measure 10 mL of N methyl 2 A pyrrolidone solution was used as a solvent and added to a beaker containing the rotor. 1.3 g of solid PEI particles were weighed and mixed with a measured amount of N... methyl 2 Pyrrolidone was mixed at 550 r·min -1 Dissolved by stirring at 55 °C for 12 h, then at 550 r·min -1 After stirring at a certain speed and at 25 °C for 3 h and then cooling, PEI was completely dissolved in N. methyl 2 A homogeneous solution A0 in pyrrolidone.
[0054] (4) Set the casting machine temperature to 190 ℃ and control the doctor blade height to 12 μm. Cast the solution A0 obtained in step (3) onto a glass plate once, and vacuum dry it at 105 ℃ for 30 min to form a film, thus forming the first layer. Then, control the doctor blade height to 13 μm and cast the suspension X obtained in step (2) onto the glass plate. 0.36 A second layer of NBTNFs ceramic fiber was formed by secondary casting on the first layer and vacuum drying at 95 °C for 5 min. Then, solution A0 was cast a third time on the second layer and vacuum dried at 105 °C for 30 min to form the third layer. This resulted in a PEI-based multilayer dielectric composite film with inorganic interlayers. Finally, the prepared PEI-based multilayer dielectric composite film with inorganic interlayers was vacuum dried at 60 °C for 12 h to obtain a preliminary sample.
[0055] (5) The prepared PEI-based multilayer dielectric composite film sample was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain a dense PEI-based multilayer dielectric composite film with inorganic interlayer, the model of which is 0-0.36-0.
[0056] The interface of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in Example 1 was tested by SEM, such as... Figure 1 and Figure 2 The SEM images show that the PEI-based multilayer dielectric composite film with inorganic interlayer is tightly bonded and has no obvious defects. The outer pure PEI layer has a single-layer thickness of 6 μm, the middle NBTNFs ceramic fiber layer has a thickness of 0.5 μm, and the overall thickness is 12.5 μm.
[0057] The PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 1 was cut into rectangles of 10 mm × 15 mm to form a diffracted film. A gold electrode with a diameter of 6 mm was deposited on the film, and then the dielectric constant was tested at room temperature. Figure 4 In this example, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayers gradually decreases with increasing frequency. At a frequency of 10 kHz, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayers prepared in this example is 5.35.
[0058] The PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 1 was cut into rectangles of 10 mm × 15 mm to form a diffracted film. A gold electrode with a diameter of 6 mm was deposited on the film, and then the dielectric loss performance was tested at room temperature. Figure 5 In this example, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayers gradually increases with increasing frequency. When the frequency is 10 kHz, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayers prepared in this example is 0.013.
[0059] The PEI-based multilayer dielectric composite film with inorganic interlayer prepared in Example 1 was cut into 10 mm × 15 mm rectangles to form a filament, and gold electrodes with a diameter of 2 mm were deposited on it. Its ferroelectric properties were then tested at 10 Hz at room temperature, and its energy storage characteristics were calculated. Figure 6 The figure shows the hysteresis loop of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example, measured at room temperature. Based on the hysteresis loop, the energy storage characteristics can be calculated. The effective energy storage density of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example is at an electric field strength of 524 MV·m. -1 Up to 12.12 J·cm -3 Table 1 shows the energy storage characteristics of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer in this example at room temperature.
[0060] Example 2 This example demonstrates the preparation of a set of PEI-based multilayer dielectric composite films containing inorganic interlayers using a solution-layer casting process. The PEI-based multilayer dielectric composite film can be simplified to a 0-X-0 model, where 0 represents the first and third layers, and X represents the volume fraction of NBTNFs in the second layer of the prepared composite film. In this example, the PEI-based multilayer dielectric composite film can be simplified to a 0-0.66-0 model, where the first and third layers are pure polyetherimide (PEI) films, and the second layer is a ceramic fiber layer with NBTNFs comprising 0.66% of the volume of the prepared composite film.
[0061] The above-mentioned method for preparing high energy density PEI-based multilayer dielectric composite thin film materials includes the following steps: (1) Measure 10 mL of isopropanol as a solvent and add it to a beaker containing a rotor. Weigh 0.050 g of NBTNFs powder, making it account for 0.66% of the volume of the prepared composite film, and mix it with the measured isopropanol.
[0062] (2) Seal the solution obtained in step (1) with plastic wrap and place it on a magnetic stirrer at 500 r / min. -1 Preliminary dispersion was achieved by stirring at room temperature for 6 hours at a certain speed. Further, the initially dispersed suspension was sonicated for 30 minutes, followed by stirring for another 1 hour. This alternating sonication and stirring process was repeated three times to obtain a homogeneous suspension X stably dispersed in isopropanol. 0.66 .
[0063] (3) Measure 10 mL of N methyl 2 A pyrrolidone solution was used as a solvent and added to a beaker containing the rotor. 1.3 g of solid PEI particles were weighed and mixed with a measured amount of N... methyl 2 Pyrrolidone was mixed at 550 r·min -1 Dissolved by stirring at 55 °C for 12 h, then at 550 r·min -1 After stirring at a certain speed and at 25 °C for 3 h and then cooling, PEI was completely dissolved in N. methyl 2 A homogeneous solution A0 in pyrrolidone.
[0064] (4) Set the casting machine temperature to 190 ℃ and control the doctor blade height to 12 μm. Cast the solution A0 obtained in step (3) onto a glass plate once, and vacuum dry it at 105 ℃ for 30 min to form a film, thus forming the first layer. Then, control the doctor blade height to 13 μm and cast the suspension X obtained in step (2) onto the glass plate. 0.66 A second layer of NBTNFs ceramic fiber was formed by secondary casting on the first layer and vacuum drying at 95 °C for 5 min. Then, solution A0 was cast a third time on the second layer and vacuum dried at 105 °C for 30 min to form the third layer. This resulted in a PEI-based multilayer dielectric composite film with inorganic interlayers. Finally, the prepared PEI-based multilayer dielectric composite film with inorganic interlayers was vacuum dried at 60 °C for 12 h to obtain a preliminary sample.
[0065] (5) The prepared PEI-based multilayer dielectric composite film sample was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain a dense PEI-based multilayer dielectric composite film with inorganic interlayer, the model of which is 0-0.66-0.
[0066] The interface of the PEI-based multilayer dielectric composite thin film material containing inorganic interlayers was tested by SEM, such as... Figure 7 and Figure 8 The SEM images show that the fabricated multilayer thin film is tightly bonded and has no obvious defects.
[0067] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a diffracted film. A 6 mm diameter gold electrode was then deposited, and the dielectric constant was tested at room temperature. Figure 10 In this example, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayers gradually decreases with increasing frequency. At a frequency of 10 kHz, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayers prepared in this example is 5.55.
[0068] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 6 mm were deposited. Dielectric loss performance was then tested at room temperature. Figure 11 In this example, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayers gradually increases with frequency. At a frequency of 10kHz, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayers prepared in this example is 0.011.
[0069] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 2 mm were deposited on it. Its ferroelectric properties were then tested at 10 Hz at room temperature, and its energy storage characteristics were calculated. Figure 12 The figure shows the hysteresis loop of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example, measured at room temperature. Based on the hysteresis loop, the energy storage characteristics can be calculated. The effective energy storage density of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example is at an electric field strength of 575 MV·m. -1 Up to 15.77 J·cm -3 Table 1 shows the energy storage characteristics of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer prepared in this example at room temperature.
[0070] Example 3 This example demonstrates the preparation of a set of PEI-based multilayer dielectric composite films with inorganic interlayers using a solution-layer casting process. The PEI-based multilayer dielectric composite film can be simplified to a 0-X-0 model, where 0 represents the first and third layers, and X represents the volume fraction of NBTNFs in the second layer of the prepared composite film. In this example, the PEI-based multilayer dielectric composite film can be simplified to a 0-0.99-0 model, where the first and third layers are pure polyetherimide (PEI) films, and the second layer is a ceramic fiber layer with NBTNFs comprising 0.99% of the volume of the prepared composite film.
[0071] The above-mentioned method for preparing PEI-based multilayer dielectric composite thin film materials includes the following steps: (1) Measure 10 mL of isopropanol as a solvent and add it to a beaker containing a rotor. Weigh 0.075 g of NBTNFs powder, making it account for 0.99% of the volume of the prepared composite film, and mix it with the measured isopropanol.
[0072] (2) Seal the solution obtained in step (1) with plastic wrap and place it on a magnetic stirrer at 500 r / min. -1Preliminary dispersion was achieved by stirring at room temperature for 6 hours at a certain speed. Further, the initially dispersed suspension was sonicated for 30 minutes, followed by stirring for another 1 hour. This alternating sonication and stirring process was repeated three times to obtain a homogeneous suspension X stably dispersed in isopropanol. 0.99 .
[0073] (3) Measure 10 mL of N methyl 2 A pyrrolidone solution was used as a solvent and added to a beaker containing the rotor. 1.3 g of solid PEI particles were weighed and mixed with a measured amount of N... methyl 2 Pyrrolidone was mixed at 550 r·min -1 Dissolved by stirring at 55 °C for 12 h, then at 550 r·min -1 After stirring at a certain speed and at 25 °C for 3 h and then cooling, PEI was completely dissolved in N. methyl 2 A homogeneous solution A0 in pyrrolidone.
[0074] (4) Set the casting machine temperature to 190 ℃ and control the doctor blade height to 12 μm. Cast the solution A0 obtained in step (3) onto a glass plate once, and vacuum dry it at 105 ℃ for 30 min to form a film, thus forming the first layer. Then, control the doctor blade height to 13 μm and cast the suspension X obtained in step (2) onto the glass plate. 0.99 A second layer of NBTNFs ceramic fiber was formed by secondary casting on the first layer and vacuum drying at 95 °C for 5 min. Then, solution A0 was cast a third time on the second layer and vacuum dried at 105 °C for 30 min to form the third layer. This resulted in a PEI-based multilayer dielectric composite film with inorganic interlayers. Finally, the prepared PEI-based multilayer dielectric composite film with inorganic interlayers was vacuum dried at 60 °C for 12 h to obtain a preliminary sample.
[0075] (5) The preliminary sample of the PEI-based multilayer dielectric composite film with inorganic interlayer was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain a dense PEI-based multilayer dielectric composite film with inorganic interlayer, the model of which is 0-0.99-0.
[0076] The interface of the PEI-based multilayer dielectric composite thin film material containing inorganic interlayers was tested by SEM, and the results are as follows: Figure 13 and Figure 14 As shown in the SEM image, the fabricated multilayer thin film is tightly bonded and has no obvious defects.
[0077] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a diffracted film. A 6 mm diameter gold electrode was then deposited, and the dielectric constant was tested at room temperature. The results are as follows: Figure 16 As shown, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example gradually decreases with increasing frequency. When the frequency is 10 kHz, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example is 5.86.
[0078] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 6 mm were deposited. Dielectric loss performance was then tested at room temperature, and the results are as follows: Figure 17 As shown, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example gradually increases with increasing frequency. When the frequency is 10 kHz, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example is 0.015.
[0079] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 2 mm were deposited on it. Its ferroelectric properties were then tested at 10 Hz at room temperature, and its energy storage characteristics were calculated. Figure 18 The figure shows the hysteresis loop of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example, measured at room temperature. Based on the hysteresis loop, the energy storage characteristics are calculated, and the effective energy storage density of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example is found to be at an electric field strength of 620 MV·m. -1 Up to 20.87 J·cm -3 Table 1 shows the energy storage characteristics of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer in this example at room temperature.
[0080] Example 4 This example demonstrates the preparation of a series of PEI-based multilayer dielectric composite films with inorganic interlayers using a solution-layer casting process. The PEI-based multilayer dielectric composite film can be simplified to a 0-X-0 model, where 0 represents the first and third layers, and X represents the volume fraction of NBTNFs in the second layer of the prepared composite film. In this example, the PEI-based multilayer dielectric composite film can be simplified to a 0-1.26-0 model, where the first and third layers are pure polyetherimide (PEI) films, and the second layer is a ceramic fiber layer with NBTNFs comprising 1.26% of the volume of the prepared composite film.
[0081] The above-mentioned method for preparing PEI-based multilayer dielectric composite thin film materials includes the following steps: (1) Measure 10 mL of isopropanol as a solvent and add it to a beaker containing a rotor. Weigh 0.100 g of NBTNFs powder, making it account for 1.26% of the volume of the prepared composite film, and mix it with the measured isopropanol.
[0082] (2) Seal the solution obtained in step (1) with plastic wrap and place it on a magnetic stirrer at 500 r / min. -1 Preliminary dispersion was achieved by stirring at room temperature for 6 hours at a certain speed. Further, the initially dispersed suspension was sonicated for 30 minutes, followed by stirring for another 1 hour. This alternating sonication and stirring process was repeated three times to obtain a homogeneous suspension X stably dispersed in isopropanol. 1.26 .
[0083] (3) Measure 10 mL of N methyl 2 A pyrrolidone solution was used as a solvent and added to a beaker containing the rotor. 1.3 g of solid PEI particles were weighed and mixed with a measured amount of N... methyl 2 Pyrrolidone was mixed at 550 r·min -1 Dissolved by stirring at 55 °C for 12 h, then at 550 r·min -1 After stirring at a certain speed and at 25 °C for 3 h and then cooling, PEI was completely dissolved in N. methyl 2 A homogeneous solution A0 in pyrrolidone.
[0084] (4) Set the casting machine temperature to 190 ℃ and control the doctor blade height to 12 μm. Cast the solution A0 obtained in step (3) onto a glass plate once, and vacuum dry it at 105 ℃ for 30 min to form a film, thus forming the first layer. Then, control the doctor blade height to 13 μm and cast the suspension X obtained in step (2) onto the glass plate. 1.26 A second layer of NBTNFs ceramic fiber was formed by secondary casting on the first layer and vacuum drying at 95 °C for 5 min. Then, solution A0 was cast a third time on the second layer and vacuum dried at 105 °C for 30 min to form the third layer. This resulted in a PEI-based multilayer dielectric composite film with inorganic interlayers. Finally, the prepared PEI-based multilayer dielectric composite film with inorganic interlayers was vacuum dried at 60 °C for 12 h to obtain a preliminary sample.
[0085] (5) The preliminary sample of the PEI-based multilayer dielectric composite film with inorganic interlayer was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain a dense PEI-based multilayer dielectric composite film with inorganic interlayer, the model of which is 0-1.26-0.
[0086] The interface of the PEI-based multilayer dielectric composite thin film material containing inorganic interlayers was tested by SEM, and the results are as follows: Figure 19 and Figure 20 As shown in the SEM image, the fabricated multilayer thin film contains small voids, but these voids do not affect the overall integrity of the film.
[0087] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a diffracted film. A 6 mm diameter gold electrode was then deposited, and the dielectric constant was tested at room temperature. The results are as follows: Figure 22 As shown, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example gradually decreases with increasing frequency. When the frequency is 10 kHz, the dielectric constant of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example is 6.11.
[0088] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 6 mm were deposited. Dielectric loss performance was then tested at room temperature, and the results are as follows: Figure 23 As shown, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example gradually increases with increasing frequency. When the frequency is 10 kHz, the dielectric loss of the PEI-based multilayer dielectric composite film with inorganic interlayer prepared in this example is 0.015.
[0089] The prepared PEI-based multilayer dielectric composite film containing inorganic interlayers was cut into 10 mm × 15 mm rectangles to form a filament, and then gold electrodes with a diameter of 2 mm were deposited on it. Its ferroelectric properties were then tested at 10 Hz at room temperature, and its energy storage characteristics were calculated. Figure 24 The figure shows the hysteresis loop of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example, measured at room temperature. Based on the hysteresis loop, the energy storage characteristics can be calculated. The effective energy storage density of the PEI-based multilayer dielectric composite film material with inorganic interlayer in this example is at an electric field strength of 515 MV·m. -1 Up to 15.88 J·cm -3 Table 1 shows the energy storage characteristics of the PEI-based multilayer dielectric composite thin film material with inorganic interlayer in this example at room temperature.
[0090] Comparative Example 1 Following the method in Example 3, a single-layer pure PEI thin film material was prepared, including the following steps: (1) Measure 10 mL of N methyl 2 A pyrrolidone solution was used as a solvent and added to a beaker containing the rotor. 1.3 g of solid PEI particles were weighed and mixed with a measured amount of N... methyl 2 Pyrrolidone was mixed at 550 r·min -1 Dissolved by stirring at 55 °C for 12 h, then at 550 r·min -1 After stirring at a certain speed and at 25 °C for 3 h and then cooling, PEI was completely dissolved in N. methyl 2 A homogeneous solution A0 in pyrrolidone.
[0091] (2) Set the casting machine temperature to 190 ℃ and control the height of the scraper to 12 μm. Cast the solution A0 obtained in step (1) once on a glass plate, vacuum dry at 105 ℃ for 30 min to form a film, and vacuum dry at 60 ℃ for 12 h to obtain a preliminary sample.
[0092] (5) The prepared preliminary sample was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain a single-layer pure PEI film material.
[0093] Comparative Example 2 According to the volume fraction of NBTNFs in the composite film in Example 3, a composite film material in which NBTNFs are uniformly distributed in PEI after physical blending of NBTNFs with PEI is prepared, including the following steps: (1) Mix 0.075 g of analytical grade NBTNFs powder and 1.3 g of PEI particles in a certain proportion so that NBTNFs accounts for 0.99% of the volume of the prepared composite film, and obtain mixture A. Measure 10 mL of isopropanol as solvent, mix mixture A with isopropanol, and add it to a beaker with a rotor.
[0094] (2) Seal the solution obtained in step (1) with plastic wrap and place it on a magnetic stirrer at 500 r / min. -1 Preliminary dispersion was achieved by stirring at room temperature for 6 hours at a certain speed. Further, the initially dispersed suspension was sonicated for 30 minutes, followed by stirring for another 1 hour. This sonication and stirring process was repeated three times to obtain a uniformly dispersed suspension X of NBTNFs and PEI in isopropanol.
[0095] (3) Set the casting machine temperature to 190 ℃ and control the height of the scraper to 13 μm. Cast the suspension X obtained in step (2) once on a glass plate, vacuum dry at 95 ℃ for 5 min to form a film, and vacuum dry at 60 ℃ for 12 h to obtain a preliminary sample.
[0096] (4) The prepared preliminary sample was heated at 200 °C for 9 min and then immediately placed in ice water for quenching to obtain NBTNFs-PEI blended composite film material.
[0097] Table 1. Energy storage characteristics of PEI-based multilayer dielectric composite thin film materials with inorganic interlayers in Examples 1-4 at room temperature.
[0098] Table 1 shows the energy storage characteristics of PEI-based multilayer dielectric composite thin film materials with inorganic interlayers in Examples 1-4 at room temperature. As shown in Table 1, the best overall energy storage characteristics were obtained when the amount of NBTNFs added to the composite film was 0.99 vol%. The breakdown electric field strength reached 620 MV·m. -1 The highest effective energy storage density is 20.87 J·cm³. -3 The energy storage efficiency reaches as high as 96.47%. Through the above examples, it can be seen that by changing the amount of filler introduced and designing the multilayer structure of the PEI-based multilayer dielectric composite film, the maximum breakdown electric field of the PEI-based multilayer dielectric composite film is effectively increased, thereby effectively improving its energy storage density. The prepared PEI-based multilayer dielectric composite film material with inorganic interlayers is expected to replace commercially available biaxially oriented polypropylene (BOPP) in the preparation of film capacitors, achieving an energy storage efficiency of 640 MV·m. -1 The energy storage density is only 2 J·cm⁻¹ -3 about.
[0099] Figure 3 , Figure 9 , Figure 15 and Figure 21 The thermogravimetric analysis (TGA) results for Examples 1-4 and monolayer pure PEI film materials are shown below. As can be seen from the figures, after heating to 800 °C, the remaining amount of the monolayer pure PEI film material was 52.73 wt%, while the remaining amounts for Examples 1-4 were 53.56 wt%, 54.24 wt%, 54.96 wt%, and 55.54 wt%, respectively.
[0100] The volume fraction of NBTNFs in the composite thin film material was calculated using the following method: (1) Calculate the mass percentage of NBT Assume that NBTNFs are completely stable at 800°C and have a 100% residual rate; let the mass percentage of NBTNFs be... wNBT (%), PEI residue rate w PEI (%),but: Total residual rate of composite film (%) = w PEI ×(100 w NBT )+ w NBT Therefore, we have: w NBT ={Total Residual Rate w PEI ) / (1 w PEI / 100)}×100% The calculated mass percentages of NBTNFs were 1.76 wt%, 3.20 wt%, 4.72 wt%, and 5.95 wt%, respectively.
[0101] (2) Calculate the volume percentage of NBT PEI density: ρ PEI = 1.27 g / cm³ 3 NBTNFs density: ρ NBT = 6.25 g / cm³ 3 (Take the midpoint between 6.0 and 6.5) Let the volume percentage of NBTNFs be VNBT, then:
[0102] Therefore, the NBTNFs introduced in Examples 1-4 accounted for 0.36 vol% (corresponding to 1.76 wt%), 0.66 vol% (corresponding to 3.20 wt%), 0.99 vol% (corresponding to 4.72 wt%), and 1.26 vol% (corresponding to 5.95 wt%) of the total composite film materials, respectively. Furthermore, thermogravimetric analysis results demonstrated the excellent temperature stability of Examples 1-4 over a wide temperature range from room temperature to 450 °C.
[0103] Figure 25This is a comparison of the hysteresis loops of the PEI-based multilayer dielectric composite film material with inorganic interlayers prepared in Example 3 of this invention, the hysteresis loops of a single-layer pure PEI film material, and the hysteresis loops of a composite material with NBTNFs uniformly distributed in PEI. Compared with a single-layer pure PEI film, the PEI-based multilayer dielectric composite film material with inorganic interlayers prepared in Example 3 of this invention has higher polarization intensity and breakdown field strength, with minimal efficiency variation, thus resulting in a higher energy storage density than a single-layer pure PEI film. Compared with composite film materials with NBTNFs uniformly distributed in PEI, the PEI-based multilayer dielectric composite film with NBTNFs inorganic interlayers prepared in Example 3 of this invention, due to its high dielectric constant inorganic filler network embedded structural design, maximizes the breakdown electric field strength of the composite material while maintaining high polarization intensity and the high energy storage efficiency of PEI, thus resulting in superior energy storage density. Therefore, the multilayer composite structure proposed in this invention has advantages.
[0104] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
Claims
1. A PEI-based multilayer dielectric composite film containing an inorganic interlayer, characterized in that, It includes a first layer, a second layer and a third layer stacked in sequence, wherein the first layer and the third layer are polyetherimide films, and the second layer is a ceramic fiber layer composed of sodium bismuth titanate nanofibers.
2. The PEI-based multilayer dielectric composite film with inorganic interlayer according to claim 1, characterized in that, The thickness of the first and third layers is 5~6 μm, and the thickness of the second layer is 0.3~0.6 μm.
3. The PEI-based multilayer dielectric composite film with inorganic interlayer according to claim 1, characterized in that, The energy storage density of the PEI-based multilayer dielectric composite film containing inorganic interlayers is between 12.12 and 20.87 J·cm⁻¹. -3 between.
4. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to any one of claims 1 to 3, characterized in that, include: S1, dispersing polyetherimide in the first solvent to obtain solution A; Bismuth sodium titanate nanofibers were dispersed in a second solvent to obtain suspension X; S2, the solution A is first cast on the substrate, dried to form a film, forming the first layer; the suspension X is second cast on the first layer, dried to form a film, forming the second layer; Solution A is cast a third time onto the second layer and dried to form a film, thus forming the third layer; the resulting sample is dried to obtain a preliminary sample. S3. The preliminary sample is quenched to obtain a PEI-based multilayer dielectric composite film with inorganic interlayer.
5. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to claim 4, characterized in that, In S1, the first solvent is N methyl 2 Pyrrolidone.
6. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to claim 4, characterized in that, In S1, the second solvent is isopropanol.
7. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to claim 4, characterized in that, In S1, sodium bismuth titanate nanofibers are dispersed in a second solvent to obtain suspension X. Specifically, sodium bismuth titanate nanofibers are added to the second solvent, and the mixture is alternately stirred and sonicated several times to obtain suspension X.
8. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to claim 4, characterized in that, S2 specifically involves: casting solution A onto a substrate for the first time, then vacuum drying at 85-125 °C for 35-45 min to form a film, creating the first layer; then casting suspension X onto the first layer for the second time, then vacuum drying at 75-95 °C for 25-35 min to form a film, creating the second layer; then casting solution A onto the second layer for the third time, then vacuum drying at 85-125 °C for 35-45 min to form the third layer; finally, vacuum drying the resulting sample at 55-75 °C for 10-14 h to obtain the preliminary sample.
9. The method for preparing a PEI-based multilayer dielectric composite film containing an inorganic interlayer according to claim 4, characterized in that, S3 specifically involves heating the preliminary sample at 195~205 ℃ for 8~10 min and then quenching it in ice water at -3~4 ℃ to obtain a PEI-based multilayer dielectric composite film with inorganic interlayer.
10. The application of the PEI-based multilayer dielectric composite film with inorganic interlayer as described in any one of claims 1 to 3 in dielectric capacitors.