Aerogel / polymer composite with wide temperature energy storage and preparation method thereof

Abstract

The application discloses an aerogel / polymer composite material with wide temperature energy storage and a preparation method thereof. The oxide aerogel with a three-dimensional skeleton structure is subjected to silanization treatment to obtain a hydrophobic oxide aerogel. Then, the hydrophobic oxide aerogel is dispersed into a solvent to obtain a dispersion liquid. Diamine monomers and acid anhydride monomers are sequentially added into the dispersion liquid, and the reaction is carried out under stirring to obtain a polyamic acid precursor solution in which the hydrophobic oxide aerogel is dispersed. The polyamic acid precursor solution is cast into a film to obtain a dry film. The dry film is subjected to imidization treatment to obtain the aerogel / polymer composite material. The obtained aerogel / polymer composite material can maintain high energy storage performance and stability even under extreme environmental temperature.

Description

Technical Field

[0001] This invention belongs to the field of dielectric composite material preparation technology, specifically relating to a wide-temperature energy storage aerogel / polymer composite material and its preparation method. Background Technology

[0002] Electrostatic capacitors have advantages such as high discharge rate, high power density, low cost, and good stability, and have been widely used in the electronics industry for a long time. dis Energy density (E) and efficiency (η) have always been the main performance indicators of dielectric materials. With the expansion of applications and the development of lightweight modern electronic devices, new demands are being placed on the energy density and temperature stability of dielectric materials. Among them, polymer-based dielectric materials stand out in the high energy density dielectric materials category due to their advantages such as high breakdown strength, ease of processing, good safety, and light weight. Furthermore, in applications such as aerospace electronic devices, insulation equipment, new energy vehicles, and oil and gas exploration, dielectric materials are required to have a wider operating temperature range (<-40℃ &>150℃).

[0003] Generally, polymer-based dielectric materials exhibit reduced leakage current at low temperatures, which is beneficial for improving electrical breakdown. However, the films become brittle at low temperatures, and partial discharge from defects becomes more pronounced, both of which are detrimental to energy storage. At high temperatures, the leakage current and Joule heating of polymer-based dielectric materials increase rapidly, limiting the improvement of energy storage density. The most common commercial energy storage dielectric material, biaxially oriented polypropylene (BOPP), suffers from relatively low energy storage density (<4 J / cm³). 3 On the other hand, the operating temperature is relatively low (<105 ℃), and as the temperature continues to rise, it will rapidly generate a large amount of Joule heat, leading to problems such as thermal runaway and thermal breakdown. In addition, the Young's modulus of the polymer is closely related to the breakdown strength, but the Young's modulus of polymers is often low, which limits their breakdown strength and energy storage performance under extreme environments.

[0004] Polyetherimide (PEI), polyimide (PI), and fluorobenzene polyester (FPE) benefit from their high glass transition temperatures (T0). g This makes it an important matrix for preparing high-temperature, high-performance dielectric materials. High T g High temperature stability often indicates excellent high-temperature stability, but it doesn't necessarily mean high energy storage performance. This is mainly because dielectric materials experience exponentially increasing leakage current under high temperature and pressure. This leakage current often leads to huge conduction losses, making it difficult to maintain high energy storage performance even at high temperatures. g High energy density is also difficult to achieve with these methods. Their conductivity increases exponentially with ambient temperature and applied electric field, leading to a significant decrease in the η and breakdown strength of the polymer film.

[0005] In recent years, incorporating fillers into polymer matrices has proven to be an effective strategy for mitigating conduction losses and thermal runaway under high-temperature conditions, making it a widely adopted method for improving the energy storage performance of dielectric materials. Studies have shown that the addition of ferroelectric ceramic fillers can effectively improve the polarization properties of dielectric materials. While ferroelectric ceramic fillers can effectively increase the dielectric constant of materials, their significant difference in dielectric properties with polymers often leads to poor compatibility with the polymer matrix, easily causing defects such as agglomeration and cracking. This agglomeration and cracking can cause premature breakdown of dielectric materials at high temperatures, low temperatures, and high voltages. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the first objective of this invention is to provide a method for preparing a wide-temperature energy storage aerogel / polymer composite material. This method involves incorporating a very small amount of oxide aerogel into a polymer. The unique three-dimensional framework structure and extremely large specific surface area of ​​the oxide aerogel create numerous trapping sites between it and the polymer matrix, resulting in a large number of trapped charge carriers. Furthermore, the oxide aerogel acts as a thermal insulation unit, forcing heat to repeatedly pass through or detour through these highly efficient insulation regions during transfer, significantly lengthening and distorting the heat flow path and increasing thermal conduction resistance. Ultimately, this allows the aerogel / polymer composite material to maintain high energy storage performance and stability even under extreme environmental temperatures.

[0007] The second objective of this invention is to provide a wide-temperature energy storage aerogel / polymer composite material prepared by the above-described preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The present invention discloses a method for preparing a wide-temperature energy storage aerogel / polymer composite material: silanizing an oxide aerogel with a three-dimensional skeleton structure to obtain a hydrophobic oxide aerogel; dispersing the hydrophobic oxide aerogel in a solvent to obtain a dispersion; sequentially adding a diamine monomer and an anhydride monomer to the dispersion; reacting under stirring to obtain a polyamic acid (PAA) precursor solution containing the hydrophobic oxide aerogel; casting the polyamic acid (PAA) precursor solution into a film to obtain a dry film; and imidizing the dry film to obtain the aerogel / polymer composite material.

[0010] The surface area of ​​the oxide aerogel is ≥600 m² / g, and the pore size of the framework is distributed in the range of 5-20 nm.

[0011] The aerogel / polymer composite material is composed of a polymer matrix and oxide aerogels with a three-dimensional skeleton structure dispersed in the polymer matrix. The mass fraction of the oxide aerogels in the aerogel / polymer composite material is 0.1~3wt%, preferably 0.25~0.75wt%.

[0012] The preparation method of this invention utilizes an oxide aerogel with a continuous three-dimensional nanoporous framework. This nanoporous framework not only provides a large specific surface area to introduce numerous interfacial traps, but also acts as a nanoscale rigid support network throughout the polymer matrix. In this invention, the oxide aerogel is first subjected to silanization treatment. This silanization treatment converts the hydrophilic silanol groups on the surface of the oxide aerogel into hydrophobic silanyl or silanoxy groups. This process significantly reduces the surface energy of the oxide aerogel, resulting in a qualitative leap in its compatibility with the polymer. This effectively suppresses the aggregation tendency of the oxide aerogel, ensuring the oxygen... The uniform distribution of the oxide aerogel in the matrix is ​​achieved by dispersing the hydrophobic oxide aerogel in a solvent to obtain a dispersion. In this invention, an in-situ polymerization method is used, sequentially adding diamine monomers and acid anhydride monomers to the dispersion. This allows the polymerization reaction of the polymer monomers to occur around the three-dimensional framework of the dispersed oxide aerogel, thereby achieving early interfacial bonding between the filler (oxide aerogel) and the polymer molecular chains. Finally, the aerogel / polymer composite material is obtained through casting and imidization. During the composite process, the long molecular chains of PEI can penetrate and entangle in the three-dimensional framework, forming a unique "topological entanglement" and "mechanical interlocking" effect. This effect greatly enhances the interfacial bonding force between the filler and the matrix, effectively transfers and disperses stress, and avoids performance failure caused by interfacial debonding. Therefore, even with a small amount of oxide aerogel incorporation, a significant enhancement of the rigidity and thermomechanical stability of the polymer matrix can be achieved.

[0013] In this invention, it is crucial to use oxide aerogel with a three-dimensional skeleton structure as raw material. If oxide powder or fiber without a three-dimensional skeleton structure is used, it is easy to agglomerate in the polymer matrix, generating a large number of defects, which is not conducive to improving mechanical properties and breakdown strength. On the other hand, conventional oxide powder or fiber is difficult to limit heat transfer, which is not conducive to improving energy storage performance at high and low temperatures.

[0014] Furthermore, experiments have shown that the composite material exhibits the best performance when the pore size distribution of the oxide aerogel framework is controlled within the range of 5-20 nm. This is because the pore size distribution matches the radius of gyration of the polymer molecular chains, providing an ideal topological structure for the subsequent formation of molecular chain entanglement.

[0015] Furthermore, in this invention, the hydrophobic oxide aerogel is dispersed in a solvent to obtain a dispersion, and then diamine monomer and acid anhydride monomer are added to the dispersion in sequence. The reaction is carried out under stirring to achieve better composite. If the hydrophobic oxide aerogel is added to the polyamic acid (PAA) precursor solution, it will cause the filler to be difficult to disperse evenly, resulting in low performance stability and uniformity. Some fillers will also cause agglomeration, introducing a large number of defects, which can easily cause local electric field concentration, seriously affecting the breakdown strength of the composite material and thus affecting its energy storage density.

[0016] In a preferred embodiment, the oxide aerogel is selected from one of SiO2 aerogel, Al2O3 aerogel, and ZrO2 aerogel, with SiO2 aerogel being the most preferred.

[0017] In a preferred embodiment, the oxide aerogel has a continuous three-dimensional nanonetwork structure, and the oxide nanoparticles in the oxide aerogel have a particle size of 5-10 nm.

[0018] In a preferred embodiment, the silanization process involves immersing the oxide aerogel in an anhydrous hexane solution containing trimethylchlorosilane (TMCS) and stirring the reaction at 40-80°C for 6-8 hours. In actual operation, after the reaction is complete, the aerogel is separated by centrifugation, washed three times with anhydrous ethanol, and finally dried.

[0019] In a preferred embodiment, the hydrophobic oxide aerogel is dispersed in N-methylpyrrolidone using ultrasound, with the ultrasound time controlled at 5-15 minutes. This ultrasound-assisted dispersion process achieves primary deagglomeration and pre-dispersion of the nano-hydrophobic oxide aerogel filler in the solvent.

[0020] In a preferred embodiment, the diamine monomer is selected from 1,3-phenylenediamine.

[0021] In a preferred embodiment, the anhydride monomer is selected from bisphenol A type diether dianhydride.

[0022] In a preferred embodiment, the molar ratio of the diamine monomer to the acid anhydride monomer is 0.8-1.2:1; more preferably, it is 1:1.

[0023] In a preferred embodiment, during the reaction under stirring, the stirring speed is controlled at 200-400 rpm, and the reaction time is 12-24 hours. In actual operation, the mixed solution obtained by sequentially adding diamine monomer and acid anhydride monomer to the dispersion is placed on a stirring table and stirred at room temperature to ensure a complete reaction and the formation of a polyamic acid (PAA) precursor solution with uniform viscosity and uniform filler distribution.

[0024] In a preferred embodiment, the casting process involves uniformly coating a polyamic acid (PAA) precursor solution onto the substrate surface, followed by drying at 70-80°C for 1-2 hours.

[0025] In this invention, during the controlled casting process, preliminary drying is carried out at low temperature. This stage mainly removes most of the solvent, forming a transitional film with a certain mechanical strength, thus avoiding film defects caused by rapid solvent evaporation.

[0026] In a preferred embodiment, the imidization process is as follows: sequentially holding at 70-80℃ for 1-2 hours, 90-100℃ for 1-2 hours, 130-150℃ for 1-2 hours, 180-200℃ for 1-2 hours, 230-250℃ for 1-2 hours, and 280-300℃ for 1-2 hours. Then, the temperature is slowly lowered to room temperature under vacuum.

[0027] The imidization process of this invention, through gradual heating, precisely controls the residual evaporation of solvent and the cyclization and dehydration reaction of polyamic acid to PEI, effectively suppressing defects such as bubbles and microcracks caused by severe thermal stress, and finally obtaining a composite material with a dense structure and stable performance.

[0028] The present invention also provides a wide-temperature energy storage aerogel / polymer composite material prepared by the above preparation method.

[0029] The beneficial effects of this invention are:

[0030] 1. The oxide aerogel incorporated into the polymer matrix has a continuous three-dimensional nanoporous framework. This structure not only provides a huge specific surface area to introduce a large number of interface traps, but also serves as a nanoscale rigid support network throughout the polymer matrix. Methylation treatment significantly reduces the surface energy of the oxide aerogel, resulting in a qualitative leap in its compatibility with the polymer. This completely suppresses the agglomeration tendency of the filler and ensures the uniform distribution of the oxide aerogel in the polymer matrix.

[0031] 2. During the composite process, the long molecular chains of PEI can penetrate and entangle within the three-dimensional framework, forming a unique "topological entanglement" and "mechanical interlocking" effect. This effect greatly enhances the interfacial bonding force between the filler and the matrix, effectively transferring and dispersing stress, and preventing performance failure caused by interfacial debonding. Therefore, even at extremely low addition levels (<1 wt%), it can significantly enhance the rigidity and thermomechanical stability of the polymer matrix while avoiding performance degradation caused by filler agglomeration.

[0032] In summary, this invention incorporates a very small amount of oxide aerogel into a polymer. The unique three-dimensional framework structure and extremely large specific surface area of ​​the oxide aerogel create numerous trapping sites between it and the polymer matrix, enabling the generation of a large number of traps that confine charge carrier movement. Furthermore, the oxide aerogel acts as a thermal insulation unit, forcing heat to repeatedly pass through or detour through these highly efficient insulation regions during transfer, significantly lengthening and distorting the heat flow path and increasing thermal conduction resistance. Ultimately, this allows the aerogel / polymer composite material to maintain high energy storage performance and stability even under extreme environmental temperatures. Attached Figure Description

[0033] Figure 1 The images show the surface SEM and EDS images of the SiO2 aerogel / PEI composite material prepared by the method in Example 1, wherein... Figure 1 (a) is a surface SEM image of the 0.5 wt% SiO2 aerogel / PEI composite material, (b) is a Si atomic elemental distribution map, (c) is a N atomic elemental distribution map, and (d) is an O atomic elemental distribution map.

[0034] Figure 2 The dielectric spectrum and dielectric temperature spectrum of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 are shown below. Figure 2 In the image, (a) represents the dielectric spectrum of the SiO2 aerogel / PEI composite material. Figure 2 (b) in the figure is the dielectric temperature spectrum of the SiO2 aerogel / PEI composite material.

[0035] Figure 3 The load-displacement curves and Young's modulus variation diagrams of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 are shown below. Figure 3 In the figure, (a) is the load-displacement curve of the SiO2 aerogel / PEI composite material. Figure 3 (b) in the figure shows the variation of Young's modulus of SiO2 aerogel / PEI composite material.

[0036] Figure 4 The leakage current density curves of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 at 150°C and 200°C are shown in the figure. Figure 4 (a) shows the leakage current density curve of the SiO2 aerogel / PEI composite material at 150℃. Figure 4 (b) in the figure is the leakage current density curve of SiO2 aerogel / PEI composite material at 200℃.

[0037] Figure 5The Weber distribution and breakdown strength of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 are shown in the diagrams at 150°C and 200°C. Figure 5 (a) in the figure is the Weber distribution diagram of the SiO2 aerogel / PEI composite material at 150℃. Figure 5 (b) in the figure shows the breakdown strength of the SiO2 aerogel / PEI composite material at 150℃. Figure 5 (c) in the figure is the Weber distribution diagram of the SiO2 aerogel / PEI composite material at 200℃. Figure 5 (d) in the figure represents the breakdown strength of the SiO2 aerogel / PEI composite material at 200℃.

[0038] Figure 6 The graph shows the energy storage performance of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 at 150℃, 200℃, -60℃, and -100℃; where... Figure 6 (a) shows the energy storage performance of the SiO2 aerogel / PEI composite material at 150℃. Figure 6 (b) shows the energy storage performance of the SiO2 aerogel / PEI composite material at 200℃. Figure 6 (c) in the figure shows the energy storage performance of the SiO2 aerogel / PEI composite material at -60℃. Figure 6 (d) in the figure represents the energy storage performance of the SiO2 aerogel / PEI composite material at -100℃. Detailed Implementation

[0039] Example 1

[0040] SiO2 aerogels with a specific surface area higher than 600 m² / g and a three-dimensional framework structure were selected. The pore size of the framework is distributed in the range of 5-20 nm, and the particle size of the SiO2 nanoparticles is 5-10 nm.

[0041] SiO2 aerogel was immersed in anhydrous hexane containing trimethylchlorosilane (TMCS) and stirred at 60°C for 6 hours. After the reaction was complete, the aerogel was separated by centrifugation, washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 80°C to obtain a surface-methylated hydrophobic SiO2 aerogel. This treatment changed the aerogel surface from hydrophilic to hydrophobic and enriched it with methyl groups. 0 mg, 1.75 mg, 3.5 mg, 5.25 mg, and 7 mg of hydrophobic SiO2 aerogel were weighed and added to N-methylpyrrolidone (NMP) solvent, respectively. The aerogels were then dispersed using an ultrasonic machine for 5 minutes to form a pre-dispersed filler slurry. The key to this step is utilizing the ultrasonic cavitation effect to break up the soft agglomerates of the aerogel, laying the foundation for subsequent uniform composite formation. In the well-dispersed filler slurry, 0.12 g of 1,3-phenylenediamine (MPD) and 0.58 g of bisphenol A diether dianhydride (BPADA) were added sequentially, with the molar ratio of the two monomers controlled at 1.0. The mixture was magnetically stirred at a constant speed of 300 rpm for 12 hours at room temperature. During this process, the polymerization reaction of polyamic acid (PAA) occurred directly around the dispersed SiO2 aerogel framework, achieving molecular-level dispersion of the filler and strong interfacial interactions. The resulting viscous PAA solution was cast onto a clean glass substrate using an adjustable-thickness doctor blade. It was then transferred to a 70°C forced-air drying oven and dried for 2 hours. This low-temperature, slow-drying process ensured stable solvent evaporation, avoiding internal stress accumulation and film defects caused by excessively rapid surface skinning. The dried SiO2 aerogel / PAA composite film was placed in a vacuum oven and subjected to a precise gradient heat treatment procedure under continuous vacuum: the temperature was increased to 80°C at a rate of 2°C / min and held for 2 hours; subsequently, the temperature was increased sequentially to 100°C and held for 1 hour, 150°C and held for 1 hour, 200°C and held for 1 hour, 250°C and held for 1 hour, and 300°C and held for 1 hour, with each temperature stage held for a specified time. After treatment, the film was cooled to room temperature in the oven. This procedure ensured that the imidization reaction from PAA to PEI was sufficient and complete, while the vacuum environment effectively eliminated small molecules of reaction byproducts and prevented oxidative degradation of the material at high temperatures. Five high-performance SiO2 aerogel / PEI composite materials were obtained, with the following mass fractions of SiO2 aerogel: 0 wt%, 0.25 wt%, 0.5 wt%, 0.75 wt%, and 1 wt%.

[0042] Performance testing

[0043] Figure 1 The images show the surface SEM and EDS images of the SiO2 aerogel / PEI composite material prepared by the method in Example 1, wherein... Figure 1(a) is a surface SEM image of the SiO2 aerogel / PEI composite material. It can be seen from the image that the filler is uniformly dispersed in the SiO2 aerogel / PEI composite material and there is no agglomeration.

[0044] Figure 2 The dielectric spectrum and dielectric temperature spectrum of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 are shown. The figures demonstrate that the SiO2 aerogel / PEI composite material exhibits excellent temperature stability in terms of dielectric constant and dielectric loss.

[0045] Figure 3 The load-displacement curves and Young's modulus variation diagrams of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 are shown. As can be seen from the figure, with the gradual increase of SiO2 aerogel content, the Young's modulus of the composite material first increases and then decreases, reaching its highest value at 0.5 wt%. The intrinsic modulus of the SiO2 aerogel skeleton is much higher than that of the polymer matrix. Through stress transfer mechanism, the movement of the PEI molecular chains in the matrix is ​​constrained, improving the overall stiffness of the material. However, when the filler content is too high, agglomeration inevitably occurs, becoming stress concentration points, inducing local plastic deformation or microcrack propagation, significantly reducing the material stiffness.

[0046] Figure 4 The graph shows the leakage current density curves of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 at 150℃ and 200℃. As can be seen from the graph, with the gradual increase of SiO2 aerogel content, the breakdown strength of the nanocomposite exhibits a trend of first decreasing and then increasing, reaching its lowest point when the SiO2 aerogel content is 0.5 wt%. SiO2 aerogel, with its wide bandgap of up to 9 eV and excellent insulation properties, can effectively trap charge, reduce leakage current density, and improve the breakdown strength of the nanocomposite. With the gradual increase of SiO2 aerogel content, the bandgap width of the nanocomposite gradually increases, indicating enhanced insulation performance. However, as the filler content gradually increases, defects such as agglomeration and cracks inevitably occur, making the nanocomposite more prone to partial discharge and hindering the reduction of leakage current density.

[0047] Figure 5The figures show the Weber distribution and breakdown strength of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 at 150°C and 200°C. As can be seen from the figures, the breakdown strength of the nanocomposite first increases and then decreases with the gradual increase of SiO2 aerogel content, reaching its highest value at a SiO2 aerogel content of 0.5 wt%. An appropriate amount of SiO2 aerogel, with its unique three-dimensional framework structure, wide bandgap, and thermal insulation effect, enables the nanocomposite to possess enhanced mechanical properties, reduced leakage current, and excellent thermal insulation performance. The ability of SiO2 aerogel to impede carrier and heat migration allows for a significant improvement in the energy density of the SiO2 aerogel / PEI composite material compared to pure PEI, even at high and low temperatures.

[0048] Figure 6 The graph shows the energy storage performance of the SiO2 aerogel / PEI composite material prepared by the method in Example 1 at 150°C, 200°C, -60°C, and -100°C. The graph shows that at 150°C, the U0.5 of the 0.5 wt% SiO2 aerogel / PEI composite material is... 90% (Energy density at efficiency above 90%) can reach 7.90 J / cm³. 3 Compared to pure PEI (2.02 J / cm³), 3 The efficiency was increased by approximately 291%. As the temperature gradually increased to 200℃, the losses of both pure PEI and SiO2 aerogel / PEI further increased, and the electric field further decreased. Ultimately, the U of pure PEI... 90% Only 1.47 J / cm 3 However, 0.5 wt% SiO2 aerogel / PEI, due to its unique structure, can still achieve U 90% 5.24 J / cm 3 This represents an improvement of approximately 256%. Lower temperatures help reduce carrier excitation and migration, effectively decreasing leakage current density. The storage density of 0.5 wt% SiO2 aerogel / PEI at -60℃ is 12.54 J / cm³. 3 , which is the pure PEI energy storage density at this time (5.75 J / cm³). 3 More than twice the breakdown strength of pure PEI. However, as the temperature continues to decrease, the film becomes brittle, and local discharge caused by interface defects severely degrades the breakdown strength of the nanocomposite, leading to a decrease in energy density. Overall, SiO2 aerogel / PEI possesses significantly higher breakdown strength and energy density than pure PEI.

[0049] This example demonstrates that an appropriate amount of SiO2 aerogel can effectively improve the energy storage performance of PEI-based polymers at high and low temperatures, and effectively extend the effective operating temperature range of the composite material.

[0050] The SiO2 aerogel / PEI composite material prepared by this invention utilizes the unique three-dimensional skeleton structure, high specific surface area, wide bandgap, and excellent thermal insulation properties of SiO2 aerogel. Compared with pure PEI, it effectively improves Young's modulus, reduces leakage current density, and reduces conduction loss, ultimately achieving excellent energy storage performance at both high and low temperatures.

[0051] Comparative Example 1

[0052] Other conditions were the same as in Example 1, except that air-phase SiO2, which lacks a three-dimensional framework structure, was used as the filler. At 150°C, the breakdown strength of 0.5 wt% air-phase SiO2 / PEI was 597 MV / m. 90% The energy density (at an efficiency higher than 90%) is only 4.76 J / cm³. 3 At 200℃, the breakdown strength of 0.5 wt% air-phase SiO2 / PEI is 506 MV / m, U 90% It can only reach 3.53 J / cm 3 .

[0053] Comparative Example 2

[0054] Other conditions were the same as in Example 1, except that crystalline SiO2 (quartz) without a three-dimensional framework structure was used as the filler. At 150°C, the breakdown strength of 0.5 wt% crystalline SiO2 / PEI was 479 MV / m. 90% It only reached 3.49 J / cm 3 At 200℃, the breakdown strength of 0.5 wt% SiO2 / PEI crystalline phase is 462 MV / m, U 90% It can only reach 2.58 J / cm 3 .

[0055] Comparative Example 3

[0056] Other conditions were the same as in Example 1, except that hollow microspheres of SiO2 without a three-dimensional framework were used as the filler. At 150°C, the breakdown strength of 0.5 wt% hollow microspheres of SiO2 / PEI was 518 MV / m. 90% Only 2.01 J / cm 3 At 200℃, the breakdown strength of 0.5 wt% hollow microspheres SiO2 / PEI is 440 MV / m, U 90% It can only reach 1.02 J / cm 3 .

Claims

1. A method for preparing a wide-temperature energy storage aerogel / polymer composite material, characterized in that: The oxide aerogel with a three-dimensional skeleton structure is silanized to obtain a hydrophobic oxide aerogel. The hydrophobic oxide aerogel is then dispersed in a solvent to obtain a dispersion. Diamine monomer and acid anhydride monomer are added to the dispersion in sequence and reacted under stirring to obtain a polyamic acid precursor solution containing the hydrophobic oxide aerogel. The polyamic acid precursor solution is cast into a film to obtain a dry film. The dry film is then imidized to obtain an aerogel / polymer composite material. The oxide aerogel is selected from SiO2 aerogel; The surface area of ​​the oxide aerogel is ≥600 m² / g, and the pore size of the framework is distributed in the range of 5-20 nm. The aerogel / polymer composite material is composed of a polymer matrix and oxide aerogels with a three-dimensional skeleton structure dispersed in the polymer matrix. The mass fraction of the oxide aerogels in the aerogel / polymer composite material is 0.1~3wt%.

2. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: The oxide aerogel has a continuous three-dimensional nano-network structure, and the oxide nanoparticles in the oxide aerogel have a particle size of 5-10 nm.

3. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: The silanization process involves immersing the oxide aerogel in an anhydrous hexane solution containing trimethylchlorosilane and stirring the mixture at 40-80°C for 6-8 hours.

4. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: Hydrophobic oxide aerogels were dispersed into N-methylpyrrolidone using ultrasound, with the ultrasound time controlled at 5-15 min.

5. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: The diamine monomer is selected from 1,3-phenylenediamine; The anhydride monomer is selected from bisphenol A type diether dianhydride; The molar ratio of the diamine monomer to the acid anhydride monomer is 0.8-1.2:

1.

6. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: During the reaction under stirring, the stirring speed is controlled at 200-400 rpm, and the time is 12-24 hours.

7. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: The casting process involves uniformly coating a polyamic acid precursor solution onto the substrate surface and then drying it at 70-80°C for 1-2 hours.

8. The method for preparing a wide-temperature energy storage aerogel / polymer composite material according to claim 1, characterized in that: The imidization process is as follows: sequentially heat treatment at 70-80℃ for 1-2 hours, at 90-100℃ for 1-2 hours, at 130-150℃ for 1-2 hours, at 180-200℃ for 1-2 hours, at 230-250℃ for 1-2 hours, and at 280-300℃ for 1-2 hours.

9. A wide-temperature energy storage aerogel / polymer composite material prepared by the preparation method according to any one of claims 1-8.

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