Five-layer pei-based composite film with high-temperature energy storage performance and preparation method

Abstract

The application discloses a five-layer PEI-based composite film with high-temperature energy storage performance and a preparation method thereof. Two-dimensional boron nitride nanosheets and PEI are uniformly dispersed to obtain a mixed solution A; 500nm, 200nm and 100nm BaTiO3 nanoparticles and PEI are uniformly dispersed respectively to obtain mixed solutions B, C and D, and the three kinds of BaTiO3 nanoparticles account for 5% of the volume of the corresponding PEI; the mixed solution A is cast, and then vacuum dried; the formed composite layer is successively cast three times under the following conditions, and vacuum dried after each time: the mixed solutions B, C and D are used in sequence in the first, second and third conditions, the mixed solutions B, D and B are used in sequence in the fourth condition, the mixed solutions D, B and D are used in sequence in the fifth condition, the mixed solutions D, C and B are used in sequence in the sixth condition, the mixed solution A is used for the fifth time of casting, and then vacuum dried, and finally vacuum dried, so that the five-layer PEI-based composite film with high-temperature energy storage performance is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-temperature energy storage polymer-based dielectric materials, and particularly relates to a five-layer PEI-based composite film with high-temperature energy storage performance and a preparation method. BACKGROUND

[0002] Among many energy storage devices, dielectric capacitors have the characteristics of high working voltage, high power density and long service life, and are key devices with large quantities and wide ranges in the fields of smart grids, new energy vehicles and high-energy pulse weapons. Compared with ceramic capacitors, polymer film capacitors have the advantages of strong flexibility, high breakdown field strength, small volume, light weight and flexible preparation process. The increasing miniaturization and integration of power electronic devices have put forward urgent demands for polymer-based high-temperature energy storage dielectric materials.

[0003] Polyetherimide (PEI) has a high glass transition temperature, a high breakdown field strength, a low dielectric loss, excellent thermal stability and good insulation performance, and has been widely used in the current field of high-temperature energy storage polymer-based dielectric materials. At present, the introduction of two-dimensional boron nitride nanosheets (BNNSs), aluminum oxide nanoparticles (Al2O3 NPs), silicon dioxide nanoparticles (SiO2 NPs) and other wide-bandgap materials into the polymer matrix PEI can inhibit the conduction loss at high temperatures, improve the breakdown field strength and energy storage efficiency, but the relatively low dielectric constant of the wide-bandgap material limits the improvement of the energy storage density. By constructing a multilayer structure, the advantages of high dielectric constant of the polarization layer and high breakdown field strength of the insulating layer can be combined to improve the energy storage density. However, excessive accumulation of Joule heat greatly increases the conduction loss, resulting in a decrease in energy storage efficiency.

[0004] Therefore, how to make the PEI-based composite film material have high energy storage density and high energy storage efficiency at high temperatures is a technical problem to be solved at present. SUMMARY

[0005] In view of the problems in the prior art, the application provides a five-layer PEI-based composite film with high-temperature energy storage performance and a preparation method. The process is simple and stable, and is suitable for industrial production. The five-layer PEI-based composite film has a high energy storage density of 6.45-7.36 J / cm 3 and a high energy storage efficiency of 73.72%-83.53% at a temperature of 150 DEG C and an electric field strength of 450 MV / m.

[0006] To achieve the above-mentioned purposes, the application adopts the following technical solutions:

[0007] A preparation method of a five-layer PEI-based composite film with high-temperature energy storage performance, comprising the following steps:

[0008] Step 1, disperse two-dimensional boron nitride nanosheets and PEI in an organic solvent, the two-dimensional boron nitride nanosheets account for 0.5% of the volume of PEI, to obtain mixed solution A; disperse 500nm BaTiO3 nanoparticles and PEI in an organic solvent to obtain mixed solution B, disperse 200nm BaTiO3 nanoparticles and PEI in an organic solvent to obtain mixed solution C, and disperse 100nm BaTiO3 nanoparticles and PEI in an organic solvent to obtain mixed solution D, the three kinds of BaTiO3 nanoparticles account for 5% of the volume of the corresponding PEI;

[0009] Step 2, cast mixed solution A, then vacuum dry at 57-63℃ for 15-20min, and then perform three times of casting on the formed BNNSs / PEI composite layer in the following six different cases, vacuum dry at 57-63℃ for 25-30min after each time of casting, to form a second composite layer, a third composite layer and a fourth composite layer in sequence:

[0010] The first case uses mixed solution B, the second case uses mixed solution C, the third case uses mixed solution D, the fourth case uses mixed solution B, mixed solution D and mixed solution B in sequence, the fifth case uses mixed solution D, mixed solution B and mixed solution D in sequence, and the sixth case uses mixed solution D, mixed solution C and mixed solution B in sequence;

[0011] Step 3, perform the fifth casting on the surface of the fourth composite layer with mixed solution A, then vacuum dry at 57-63℃ for 35-40min to form a BNNSs / PEI composite layer, and finally vacuum dry at 72-78℃ for 5-8h to obtain a five-layer PEI-based composite film with high-temperature energy storage performance.

[0012] Preferably, step 1 adopts a liquid phase exfoliation method to prepare two-dimensional boron nitride nanosheets from hexagonal boron nitride in N,N-dimethylformamide.

[0013] Further, step 1 disperses 1.5g of hexagonal boron nitride powder in 150ml of N,N-dimethylformamide, first ultrasonic for 6-12h, then centrifuge at a speed of 3000-3600r / min for 8-10min, and finally vacuum dry the precipitate at 70-80℃ for 12-15h to obtain two-dimensional boron nitride nanosheets.

[0014] Preferably, the organic solvent in step 1 is N-methyl-2-pyrrolidone.

[0015] Preferably, in step 1, the ratio of PEI to organic solvent in mixed solution A, mixed solution B, mixed solution C and mixed solution D is 1g:10ml.

[0016] Preferably, in step 1, PEI and two-dimensional boron nitride nanosheets are dispersed by ultrasonic for 2-3.5 h, and then magnetic stirring is carried out at a rotating speed of 350-420 r / min and a temperature of 40-45 DEG C for 8-11 h to obtain a mixed solution A.

[0017] Preferably, in step 1, PEI and corresponding BaTiO3 nanoparticles are dispersed by ultrasonic for 4-6.5 h, and then magnetic stirring is carried out at a rotating speed of 475-535 r / min and a temperature of 43-53 DEG C for 11-13.5 h to obtain a mixed solution B, a mixed solution C and a mixed solution D.

[0018] Preferably, in step 2, the temperature of the casting machine is set to 175-183 DEG C, the speed of the doctor blade is adjusted to 9-14 mm / s, and the height of the doctor blade is adjusted to 5-7 um, and then all the casting processes are carried out.

[0019] A five-layer PEI-based composite film with high-temperature energy storage performance prepared by the preparation method of the five-layer PEI-based composite film with high-temperature energy storage performance.

[0020] Preferably, the thickness of the composite film is 25-35 um, and the composite film has a energy storage density of 6.45-7.36 J / cm 3 and an energy storage efficiency of 73.72%-83.53% at a temperature of 150 DEG C and an electric field intensity of 450 MV / m.

[0021] Compared with the prior art, the present application has the following beneficial technical effects:

[0022] The application discloses a preparation method of a five-layer PEI-based composite film with high-temperature energy storage performance. BNNSs and BaTiO3 nanoparticles with different particle sizes are respectively dispersed in an organic solvent by a solution blending method, and finally, a five-layer PEI-based composite film with excellent high-temperature energy storage performance is prepared by a laminated casting method, wherein the outer layers on both sides are BNNSs / PEI composite layers, and the middle three layers are composite layers composed of BaTiO3 NPs with different particle sizes (100 nm, 200 nm and 500 nm) and PEI. Specifically, the five-layer PEI-based composite film can be 500nm BaTiO3 NPs / PEI composite layer, 200nm BaTiO3 NPs / PEI composite layer and 100nm BaTiO3 NPs / PEI composite layer from bottom to top, 100nm BaTiO3 NPs / PEI composite layer, 500nm BaTiO3 NPs / PEI composite layer and 100nm BaTiO3 NPs / PEI composite layer, or 100nm BaTiO3 NPs / PEI composite layer, 200nm BaTiO3 NPs / PEI composite layer and 500nm BaTiO3 NPs / PEI composite layer. The application can break through the limitation of regulating the energy storage performance of the multilayer structure composite film composed of a heat-conducting / insulating layer and a polarization layer, and use different functional layers as performance regulating units. The BNNSs / PEI composite layer is used as the heat-conducting / insulating layer, the BNNSs have high insulation and excellent thermal conductivity, can reduce the leakage current, improve the heat dissipation capacity, and thus improve the breakdown field strength and the energy storage efficiency. The BaTiO3 NPs / PEI composite layer with different particle sizes is used as the polarization layer, the BaTiO3 NPs with different particle sizes have high polarization strength and can improve the energy storage density. On the basis of combining the heat-conducting / insulating layer and the polarization layer to complement the advantages of the performance, the arrangement mode of the different functional layers is changed, the macroscopic interface structure is designed, the uniform distribution of the electric field is promoted, the interface barrier effect is formed, the leakage current is reduced, and thus the synergistic improvement of the energy storage density and the energy storage efficiency at high temperature is realized.

[0023] The maximum use temperature of commercial bidirectional stretched polypropylene (BOPP) in short-term operation is < 105℃, and in long-term operation is ≤ 85℃. Therefore, in order to install a BOPP film capacitor in a power inverter of a hybrid electric vehicle, a cooling system must be used to reduce the ambient temperature from 140℃ to 70℃. This not only brings additional weight, volume and energy consumption, but also reduces the reliability and efficiency of the equipment. The five-layer PEI-based composite film prepared in the present application has excellent high-temperature energy storage performance, which is expected to replace BOPP to prepare film capacitors, to meet the actual application requirements of high-temperature energy storage composite films in special fields such as aerospace and new energy electric vehicles. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 XRD pattern of the two-dimensional boron nitride nanosheet (BNNSs) prepared in the present application;

[0025] Figure 2 SEM pattern of the two-dimensional boron nitride nanosheet (BNNSs) prepared in the present application;

[0026] Figure 3 Cross-sectional SEM pattern of the five-layer PEI-based composite film material prepared in Example 1 of the present application;

[0027] Figure 4 Electrical hysteresis loop pattern of the five-layer PEI-based composite film material prepared in Example 1 of the present application at 150℃;

[0028] Figure 5 Cross-sectional SEM pattern of the five-layer PEI-based composite film material prepared in Example 2 of the present application;

[0029] Figure 6 Electrical hysteresis loop pattern of the five-layer PEI-based composite film material prepared in Example 2 of the present application at 150℃;

[0030] Figure 7 Cross-sectional SEM pattern of the five-layer PEI-based composite film material prepared in Example 3 of the present application;

[0031] Figure 8 Electrical hysteresis loop pattern of the five-layer PEI-based composite film material prepared in Example 3 of the present application at 150℃;

[0032] Figure 9 Cross-sectional SEM pattern of the five-layer PEI-based composite film material prepared in Example 4 of the present application;

[0033] Figure 10 Electrical hysteresis loop pattern of the five-layer PEI-based composite film material prepared in Example 4 of the present application at 150℃;

[0034] Figure 11 Cross-sectional SEM image of the five-layer PEI-based composite film material prepared in Example 5 of the present application;

[0035] Figure 12 Electrical hysteresis loop diagram of the five-layer PEI-based composite film material prepared in Example 5 of the present application at 150℃;

[0036] Figure 13 Cross-sectional SEM image of the five-layer PEI-based composite film material prepared in Example 6 of the present application;

[0037] Figure 14 Electrical hysteresis loop diagram of the five-layer PEI-based composite film material prepared in Example 6 of the present application at 150℃. DETAILED DESCRIPTION

[0038] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0039] The present application is a five-layer PEI-based composite film with high-temperature energy storage performance, which is prepared by first using a liquid phase exfoliation method to obtain BNNSs, then using a solution blending method to disperse the BNNSs and BaTiO3 NPs of different particle sizes in PEI in an organic solvent to obtain BNNSs / PEI mixed solution and BaTiO3 NPs / PEI mixed solution of different particle sizes, and finally using a laminated casting method to obtain a five-layer PEI-based composite film, wherein the two outer layers are BNNSs / PEI composite layers with high thermal conductivity and high insulation, and the middle three layers are BaTiO3 NPs / PEI composite layers of different particle sizes with high polarization strength, and the total thickness is 25-35μm.

[0040] Specifically, the following steps are included:

[0041] (1) Disperse 1.5g of hexagonal boron nitride (h-BN) powder in 150ml of N,N-dimethylformamide, ultrasonic for 6-12h, then centrifuge at a speed of 3000-3600r / min for 8-10min, and finally vacuum dry the precipitate at 70-80℃ for 12-15h to obtain two-dimensional boron nitride nanosheets (BNNSs).

[0042] (2) Disperse the BNNSs and PEI in an organic solvent N-methyl-2-pyrrolidone (NMP), with the BNNSs doping amount being 0.5% of the volume of PEI, and the ratio of PEI and NMP being 1g:10ml, first ultrasonic for 2-3.5h, then magnetic stirring at a speed of 350-420r / min and a temperature of 40-45℃ for 8-11h to obtain a BNNSs / PEI mixed solution A;

[0043] 500nm BaTiO3 NPs, 200nm BaTiO3 NPs and 100nm BaTiO3 NPs were dispersed in NMP with PEI respectively, the volume of each size BaTiO3 NPs accounted for 5% of the volume of corresponding PEI, the ratio of PEI and NMP was 1g:10ml, first ultrasonic for 4-6.5h, then magnetic stirring at 475-535r / min and 43-53℃ for 11-13.5h, to prepare 500nm (large particle size) BaTiO3 NPs / PEI mixed solution X1, 200nm (medium particle size) BaTiO3 NPs / PEI mixed solution X2 and 100nm (small particle size) BaTiO3 NPs / PEI mixed solution X3.

[0044] (3) The temperature of the casting machine was set to 175-183℃, the speed of the doctor blade was adjusted to 9-14mm / s, and the height of the doctor blade was controlled to 5-7μm. The mixed solution A was first cast on a glass plate, and then vacuum dried at 57-63℃ for 15-20min to form a film (to form a BNNSs / PEI composite layer). The mixed solution X1, the mixed solution X2 and the mixed solution X3 were respectively cast three times on the glass plate on which the first film was formed, and then vacuum dried at 57-63℃ for 25-30min to form a second composite layer, a third composite layer and a fourth composite layer in turn. The mixed solution A was cast for the fifth time on the glass plate on which the four films were formed, and then vacuum dried at 57-63℃ for 35-40min to form a BNNSs / PEI composite layer. Finally, the five-layer PEI-based composite film materials with different structures were vacuum dried at 72-78℃ for 5-8h to volatilize the solvent, and then peeled off from the glass plate to obtain five-layer PEI-based composite film materials with different structures:

[0045] 1, all using the mixed solution X1, and the middle three layers were all 500nm BaTiO3 NPs / PEI composite layers;

[0046] 2, all using the mixed solution X2, and the middle three layers were all 200nm BaTiO3 NPs / PEI composite layers;

[0047] 3, all using the mixed solution X3, and the middle three layers were all 100nm BaTiO3 NPs / PEI composite layers;

[0048] 4, using the mixed solution X1, the mixed solution X3 and the mixed solution X1 in turn, and the middle three layers from bottom to top were 500nm BaTiO3 NPs / PEI composite layer, 100nm BaTiO3 NPs / PEI composite layer and 500nm BaTiO3 NPs / PEI composite layer in turn.

[0049] 5, using mixed solution X3, mixed solution X1 and mixed solution X3 in turn, the middle three layers are 100nm BaTiO3 NPs / PEI composite layer, 500nm BaTiO3 NPs / PEI composite layer and 100nm BaTiO3 NPs / PEI composite layer from bottom to top in turn;

[0050] 6, using mixed solution X3, mixed solution X2 and mixed solution X1 in turn, the middle three layers are 100nm BaTiO3 NPs / PEI composite layer, 200nm BaTiO3 NPs / PEI composite layer and 500nm BaTiO3 NPs / PEI composite layer from bottom to top in turn.

[0051] Performance test:

[0052] The prepared BNNSs are subjected to X-ray diffraction test;

[0053] The prepared BNNSs are subjected to SEM test;

[0054] The prepared five-layer PEI-based composite film materials with different structures are subjected to cross-section SEM test;

[0055] The prepared film sample is cut into a rectangle of 12mm*15mm, prepared into a film, plated with a gold electrode with a diameter of 2mm, then subjected to ferroelectric performance test at a temperature of 150℃, and thus the calculation formula of the energy storage performance, total energy storage density (U), effective energy storage density (U e ) and energy storage efficiency (η) is:

[0056]

[0057]

[0058]

[0059] Wherein P max represents the maximum polarization intensity, P r represents the remanent polarization intensity, E represents the electric field intensity, and P represents the polarization intensity.

[0060] The content of the present application can be further understood through the following examples, but it is not a limitation of the present application.

[0061] Example 1:

[0062] The five-layer structure PEI-based composite film material is prepared by using a liquid phase stripping method, a solution blending method and a laminated flow casting method, wherein two outer layers are BNNSs / PEI composite layers, and the middle three layers are different particle size BaTiO3 NPs / PEI composite layers.

[0063] The preparation method of the five-layer structure PEI-based composite film material includes the following steps:

[0064] (1) 1.5g of h-BN powder is dispersed in 150ml of N,N-dimethylformamide, ultrasonic treatment is performed for 9h, the mixed solution is centrifuged at 3500r / min for 9min, and finally the precipitate is vacuum dried at 75℃ for 13h to obtain BNNSs.

[0065] (2) 0.0258g of BNNSs and 2.4g of PEI are dispersed in 24ml of NMP, at this time the volume of BNNSs accounts for 0.5vol% of the volume of PEI, ultrasonic treatment is performed for 2.5h, magnetic stirring is performed at a speed of 370r / min and a temperature of 43℃ for 9h, to prepare a BNNSs / PEI mixed solution A;

[0066] 1.0659g of 500nm BaTiO3 NPs and 3.6g of PEI are dispersed in 36ml of NMP, at this time the volume of 500nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic treatment is performed for 5.5h, magnetic stirring is performed at a speed of 510r / min and a temperature of 48℃ for 12.5h, to prepare a 500nm BaTiO3 NPs / PEI mixed solution X1.

[0067] (3) The temperature of the casting machine is set to 182℃, the speed of the doctor blade is adjusted to 13mm / s, and the height of the doctor blade is controlled to 6μm. The mixed solution A is first cast on a glass plate, and is placed in a vacuum drying box at 62℃ for 17min to form a film; the mixed solution X1 is cast on the glass plate on which the first film is formed, and is placed in a vacuum drying box at 62℃ for 27min to form a film for three times; the mixed solution A is cast on the glass plate on which the fourth film is formed, and is placed in a vacuum drying box at 62℃ for 37min to form a film; finally, the five-layer structure PEI-based composite film material BLLLB is vacuum dried at 75℃ for 7h to volatilize the solvent, and is removed from the glass plate to obtain the five-layer structure PEI-based composite film material.

[0068] (4) The prepared BNNSs were tested by X-ray diffraction, as shown in Fig. 4. It can be seen from the figure that the BNNSs obtained in the embodiment have a hexagonal structure. Figure 1

[0069] (5) The prepared BNNSs were tested by SEM, as shown in Fig. 5. It can be seen from the figure that the BNNSs obtained in the embodiment have a clear flaky structure, and the transverse particle size is about 100 nm to 500 nm. Figure 2

[0070] (6) The prepared five-layer structure PEI-based composite film material BLLLB was tested by cross-section SEM, as shown in Fig. 6. It can be seen from the figure that the composite film material obtained in the embodiment has a clear five-layer structure, the interface is well connected without structural defects, and the total thickness is about 30 μm. The two outer layers are PEI composite layers containing flaky BNNSs, and the three middle layers are PEI composite layers containing large particle size 500 nm BaTiO3 NPs, and the thickness of each layer is about 6 μm. Figure 3

[0071] (7) The prepared film sample was cut into a rectangle of 12 mm x 15 mm to prepare a film, a gold electrode with a diameter of 2 mm was plated, and then a ferroelectric performance test was performed at a temperature of 150°C, and the energy storage performance was calculated. Figure 4 The hysteresis loop of the five-layer structure PEI-based composite film material BLLLB in the embodiment measured at 150°C, and the energy storage performance calculation based on the hysteresis loop can be obtained. The effective energy storage density of the five-layer structure PEI-based composite film material BLLLB in the embodiment is 6.45 J / cm 3 at an electric field intensity of 450 MV / m, and the energy storage efficiency is 83.53%. Table 1 shows the energy storage performance of the five-layer structure PEI-based composite film material BLLLB in the embodiment at 150°C.

[0072] Example 2:

[0073] The five-layer structure PEI-based composite film material is prepared by using a liquid phase exfoliation method, a solution blending method and a lamination casting method. The two outer layers are BNNSs / PEI composite layers, and the three middle layers are different particle size BaTiO3 NPs / PEI composite layers. In this example, the two outer layers of the five-layer structure composite film material are BNNSs / PEI composite layers, and the three middle layers are 200 nm BaTiO3 NPs / PEI composite layers, which can be simplified as a BMMMB model, wherein B represents a BNNSs / PEI composite layer, and M represents a 200 nm BaTiO3 NPs / PEI composite layer.

[0074] The preparation method of the above-mentioned five-layer structure PEI-based composite film material comprises the following steps: ​​​

[0075] (1) 1.5 g h-BN powder was dispersed in 150 ml N,N-dimethylformamide, ultrasonic for 9 h, the mixed solution was centrifuged at 3500 r / min for 9 min, and finally the precipitate was vacuum dried at 75°C for 13 h to obtain BNNSs.

[0076] (2) 0.0258 g BNNSs and 2.4 g PEI were dispersed in 24 ml NMP, at this time the volume of BNNSs accounted for 0.5 vol% of the volume of PEI, ultrasonic for 2.5 h, magnetic stirring at a speed of 370 r / min and a temperature of 43°C for 9 h, to prepare a BNNSs / PEI mixed solution A;

[0077] 1.0659 g 200 nm BaTiO3 NPs and 3.6 g PEI were dispersed in 36 ml NMP, at this time the volume of 200 nm BaTiO3 NPs accounted for 5 vol% of the volume of PEI, ultrasonic for 5.5 h, magnetic stirring at a speed of 510 r / min and a temperature of 48°C for 12.5 h, to prepare a 200 nm BaTiO3 NPs / PEI mixed solution X2.

[0078] (3) The temperature of the casting machine was set to 182°C, the speed of the doctor blade was adjusted to 13 mm / s, and the height of the doctor blade was controlled to 6 μm. The mixed solution A was first cast on a glass plate, and the film was formed by vacuum drying at 62°C for 17 min in a vacuum drying box. The mixed solution X2 was cast three times on the glass plate on which the first film was formed, and the film was formed by vacuum drying at 62°C for 27 min in a vacuum drying box after each casting. The mixed solution A was cast for the fifth time on the glass plate on which the four films were formed, and the film was formed by vacuum drying at 62°C for 37 min in a vacuum drying box. Finally, the five-layer PEI-based composite film material BMMMB was obtained by vacuum drying at 75°C for 7 h to volatilize the solvent, and then it was peeled off from the glass plate.

[0079] (4) The cross-section SEM test of the prepared five-layer PEI-based composite film material BMMMB was carried out, as shown in FIG. 1. It can be seen from the figure that the composite film material obtained in the embodiment presents a clear five-layer structure, the interface is well connected without structural defects, and the total thickness is about 30 μm. The two outer layers are PEI composite layers containing flaky BNNSs, and the middle three layers are PEI composite layers containing medium particle size 200 nm BaTiO3 NPs, and the thickness of each layer is about 6 μm. Figure 5

[0080] (5) The prepared film sample was cut into a rectangle of 12 mm x 15 mm to prepare a film sample, a gold electrode with a diameter of 2 mm was plated, and then the ferroelectric performance test was carried out at a temperature of 150°C, and the energy storage performance was calculated.​Figure 6 The hysteresis loop of the five-layer structure PEI-based composite film material BMMMB of the present example was measured at 150°C, and based on the hysteresis loop, the effective energy storage density of the five-layer structure PEI-based composite film material BMMMB of the present example was calculated to be 6.77 J / cm 3 at an electric field strength of 450 MV / m, and the energy storage efficiency was 81.46%. Table 1 shows the energy storage performance of the five-layer structure PEI-based composite film material BMMMB of the present example at 150°C.

[0081] Example 3:

[0082] The present application adopts a liquid phase exfoliation method, a solution blending method and a lamination casting method to prepare a five-layer structure PEI-based composite film material, wherein the two outer layers are BNNSs / PEI composite layers, and the middle three layers are different particle size BaTiO3 NPs / PEI composite layers. In the present example, the two outer layers of the five-layer structure composite film material are BNNSs / PEI composite layers, and the middle three layers are all 100 nm BaTiO3 NPs / PEI composite layers, which can be simplified as a BSSSB model, wherein B represents a BNNSs / PEI composite layer, and S represents a small particle size 100 nm BaTiO3 NPs / PEI composite layer.

[0083] The preparation method of the above-mentioned five-layer structure PEI-based composite film material comprises the following steps:

[0084] (1) 1.5 g of h-BN powder was dispersed in 150 ml of N,N-dimethylformamide, ultrasonic treatment was performed for 9 h, the mixed solution was centrifuged at 3500 r / min for 9 min, and finally the precipitate was vacuum dried at 75°C for 13 h to obtain BNNSs.

[0085] (2) 0.0258 g of BNNSs and 2.4 g of PEI were dispersed in 24 ml of NMP, at this time the volume of BNNSs accounted for 0.5 vol% of the volume of PEI, ultrasonic treatment was performed for 2.5 h, and magnetic stirring was performed at a speed of 370 r / min and a temperature of 43°C for 9 h, to prepare a BNNSs / PEI mixed solution A;

[0086] 1.0659 g of 100 nm BaTiO3 NPs and 3.6 g of PEI were dispersed in 36 ml of NMP, at this time the volume of 100 nm BaTiO3 NPs accounted for 5 vol% of the volume of PEI, ultrasonic treatment was performed for 5.5 h, and magnetic stirring was performed at a speed of 510 r / min and a temperature of 48°C for 12.5 h, to prepare a 100 nm BaTiO3 NPs / PEI mixed solution X3.

[0087] (3) Set the casting machine temperature to 182℃, adjust the doctor blade speed to 13mm / s, and control the doctor blade height to 6μm. Cast the mixed solution A on a glass plate for the first time, and place it in a vacuum drying oven at 62℃ for 17min to form a film. Cast the mixed solution X3 on the glass plate after the first film formation three times, and place it in a vacuum drying oven at 62℃ for 27min each time to form a film. Cast the mixed solution A on the glass plate after the fourth film formation for the fifth time, and place it in a vacuum drying oven at 62℃ for 37min to form a film. Finally, vacuum dry the five-layer PEI-based composite film material BSSSB at 75℃ for 7h to allow the solvent to evaporate, and peel it off from the glass plate to obtain the five-layer PEI-based composite film material.

[0088] (4) The prepared five-layer PEI-based composite thin film material BSSSB was subjected to cross-sectional SEM testing, such as... Figure 7 As shown in the figure, the composite thin film material obtained in this embodiment exhibits a distinct five-layer structure with good interface bonding and no structural defects, and a total thickness of approximately 30 μm. The two outer layers are PEI composite layers containing sheet-like BNNSs, while the three middle layers are PEI composite layers containing small-particle-size 100 nm BaTiO3 NPs, each with a thickness of approximately 6 μm.

[0089] (5) Cut the prepared thin film sample into a rectangle of 12mm×15mm to prepare a diffracted film, deposit a gold electrode with a diameter of 2mm, and then test the ferroelectric performance at a temperature of 150℃, and calculate the energy storage performance accordingly. Figure 8 The hysteresis loop of the five-layer PEI-based composite thin film material BSSSB in this embodiment was measured at 150°C. Based on the hysteresis loop, the energy storage performance was calculated, and the effective energy storage density of the five-layer PEI-based composite thin film material BSSSB in this embodiment at an electric field strength of 450 MV / m is 6.92 J / cm². 3 The energy storage efficiency is 76.86%. Table 1 shows the energy storage performance of the five-layer PEI-based composite thin film material BSSSB in this embodiment at 150°C.

[0090] Example 4:

[0091] The five-layer structure PEI-based composite film material is prepared by liquid phase exfoliation method, solution blending method and laminated flow casting method, wherein two outer layers are BNNSs / PEI composite layers, and the middle three layers are different particle size BaTiO3 NPs / PEI composite layers. In the example, the two outer layers of the five-layer structure composite film material are BNNSs / PEI composite layers, and the middle three layers from bottom to top are 500nm BaTiO3 NPs / PEI composite layer, 100nm BaTiO3 NPs / PEI composite layer and 500nm BaTiO3 NPs / PEI composite layer, which can be simplified as BLSLB model, wherein B represents BNNSs / PEI composite layer, L represents 500nm BaTiO3 NPs / PEI composite layer, and S represents 100nm BaTiO3 NPs / PEI composite layer.

[0092] The preparation method of the five-layer structure PEI-based composite film material includes the following steps:

[0093] (1) 1.5g h-BN powder is dispersed in 150ml N,N-dimethylformamide, ultrasonic is 9h, the mixed solution is centrifuged at 3500r / min for 9min, and finally the precipitate is vacuum dried at 75℃ for 13h to obtain BNNSs.

[0094] (2) 0.0258g BNNSs and 2.4g PEI are dispersed in 24ml NMP, at this time the volume of BNNSs accounts for 0.5vol% of the volume of PEI, ultrasonic is 2.5h, magnetic stirring is carried out at 370r / min and 43℃ for 9h, to prepare BNNSs / PEI mixed solution A;

[0095] 0.7106g 500nm BaTiO3 NPs and 2.4g PEI are dispersed in 24ml NMP, at this time the volume of 500nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic is 5.5h, magnetic stirring is carried out at 510r / min and 48℃ for 12.5h, to prepare 500nm BaTiO3 NPs / PEI mixed solution X1;

[0096] 0.3553g 100nm BaTiO3 NPs and 1.2g PEI are dispersed in 12ml NMP, at this time the volume of 100nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic is 5.5h, magnetic stirring is carried out at 510r / min and 48℃ for 12.5h, to prepare 100nm BaTiO3 NPs / PEI mixed solution X3.

[0097] (3) Set the casting machine temperature to 182℃, adjust the scraper speed to 13mm / s, and control the scraper height to 6μm. Mixed solution A was first cast on a glass plate and then vacuum dried at 62°C for 17 min in a vacuum drying oven to form a film. Mixed solution X1 was second cast on the glass plate after the first film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X3 was third cast on the glass plate after the second film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X1 was fourth cast on the glass plate after the third film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution A was fifth cast on the glass plate after the fourth film formation and then vacuum dried at 62°C for 37 min in a vacuum drying oven to form a film. Finally, the five-layer PEI-based composite film material BLSLB was vacuum dried at 75°C for 7 h to allow the solvent to evaporate and then peeled off from the glass plate to obtain the five-layer PEI-based composite film material.

[0098] (4) The prepared five-layer PEI-based composite thin film material BLSLB was subjected to cross-sectional SEM testing, such as... Figure 9 As shown in the figure, the composite thin film material obtained in this embodiment exhibits a distinct five-layer structure with good interface bonding and no structural defects, and a total thickness of approximately 30 μm. The two outer layers are PEI composite layers containing sheet-like BNNSs, while the three middle layers, from bottom to top, are a PEI composite layer containing large-particle-size 500 nm BaTiO3 NPs, a PEI composite layer containing small-particle-size 100 nm BaTiO3 NPs, and a PEI composite layer containing large-particle-size 500 nm BaTiO3 NPs, each with a thickness of approximately 6 μm.

[0099] (5) Cut the prepared thin film sample into a rectangle of 12mm×15mm to prepare a diffracted film, deposit a gold electrode with a diameter of 2mm, and then test the ferroelectric performance at a temperature of 150℃, and calculate the energy storage performance accordingly. Figure 10 The hysteresis loop of the five-layer PEI-based composite thin film material BLSLB in this embodiment was measured at 150°C. Based on the hysteresis loop, the energy storage performance was calculated, and the effective energy storage density of the five-layer PEI-based composite thin film material BLSLB in this embodiment at an electric field strength of 450 MV / m is 6.51 J / cm². 3 The energy storage efficiency is 78.53%. Table 1 shows the energy storage performance of the five-layer PEI-based composite thin film material BLSLB in this embodiment at 150°C.

[0100] Example 5:

[0101] The five-layer structure PEI-based composite film material is prepared by liquid phase exfoliation method, solution blending method and laminated flow casting method, wherein two outer layers are BNNSs / PEI composite layers, and the middle three layers are different particle size BaTiO3 NPs / PEI composite layers. In the example, the two outer layers of the five-layer structure composite film material are BNNSs / PEI composite layers, and the middle three layers from bottom to top are 100nm BaTiO3 NPs / PEI composite layer, 500nm BaTiO3 NPs / PEI composite layer and 100nm BaTiO3 NPs / PEI composite layer, which can be simplified as BSLSB model, wherein B represents BNNSs / PEI composite layer, S represents 100nm BaTiO3 NPs / PEI composite layer, and L represents 500nm BaTiO3 NPs / PEI composite layer.

[0102] The preparation method of the above-mentioned five-layer structure PEI-based composite film material comprises the following steps:

[0103] (1) 1.5g h-BN powder is dispersed in 150ml N,N-dimethylformamide, ultrasonic treatment is performed for 9h, the mixed solution is centrifuged at 3500r / min for 9min, and finally the precipitate is vacuum dried at 75℃ for 13h to obtain BNNSs.

[0104] (2) 0.0258g BNNSs and 2.4g PEI are dispersed in 24ml NMP, at this time the volume of BNNSs accounts for 0.5vol% of the volume of PEI, ultrasonic treatment is performed for 2.5h, magnetic stirring is performed at a speed of 370r / min and a temperature of 43℃ for 9h, to prepare BNNSs / PEI mixed solution A;

[0105] 0.3553g 500nm BaTiO3 NPs and 1.2g PEI are dispersed in 12ml NMP, at this time the volume of 500nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic treatment is performed for 5.5h, magnetic stirring is performed at a speed of 510r / min and a temperature of 48℃ for 12.5h, to prepare 500nm BaTiO3 NPs / PEI mixed solution X1;

[0106] 0.7106g 100nm BaTiO3 NPs and 2.4g PEI are dispersed in 24ml NMP, at this time the volume of 100nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic treatment is performed for 5.5h, magnetic stirring is performed at a speed of 510r / min and a temperature of 48℃ for 12.5h, to prepare 100nm BaTiO3 NPs / PEI mixed solution X3.

[0107] (3) Set the casting machine temperature to 182℃, adjust the scraper speed to 13mm / s, and control the scraper height to 6μm. Mixed solution A was first cast on a glass plate and then vacuum dried at 62°C for 17 min in a vacuum drying oven to form a film. Mixed solution X3 was second cast on the glass plate after the first film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X1 was third cast on the glass plate after the second film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X3 was fourth cast on the glass plate after the third film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution A was fifth cast on the glass plate after the fourth film formation and then vacuum dried at 62°C for 37 min in a vacuum drying oven to form a film. Finally, the five-layer PEI-based composite film material BSLSB was vacuum dried at 75°C for 7 h to allow the solvent to evaporate and then peeled off from the glass plate to obtain the five-layer PEI-based composite film material.

[0108] (4) The prepared five-layer PEI-based composite thin film material BSLSB was subjected to cross-sectional SEM testing, such as... Figure 11 As shown in the figure, the composite thin film material obtained in this embodiment exhibits a distinct five-layer structure with good interface bonding and no structural defects, and a total thickness of approximately 30 μm. The two outer layers are PEI composite layers containing sheet-like BNNSs, while the three middle layers, from bottom to top, are a PEI composite layer containing 100 nm BaTiO3 NPs, a PEI composite layer containing 500 nm BaTiO3 NPs, and a PEI composite layer containing 100 nm BaTiO3 NPs, each with a thickness of approximately 6 μm.

[0109] (5) Cut the prepared thin film sample into a rectangle of 12mm×15mm to prepare a diffracted film, deposit a gold electrode with a diameter of 2mm, and then test the ferroelectric performance at a temperature of 150℃, and calculate the energy storage performance accordingly. Figure 12 The hysteresis loop of the five-layer PEI-based composite thin film material BSLSB in this embodiment was measured at 150°C. Based on the hysteresis loop, the energy storage performance was calculated, and the effective energy storage density of the five-layer PEI-based composite thin film material BSLSB in this embodiment at an electric field strength of 450 MV / m is 6.87 J / cm². 3 The energy storage efficiency is 73.72%. Table 1 shows the energy storage performance of the five-layer PEI-based composite thin film material BSLSB in this embodiment at 150°C.

[0110] Example 6:

[0111] The five-layer structure PEI-based composite film material is prepared by liquid phase exfoliation method, solution blending method and laminated flow casting method, wherein two outer layers are BNNSs / PEI composite layers, and the middle three layers are different particle size BaTiO3 NPs / PEI composite layers. In this example, the two outer layers of the five-layer structure composite film material are BNNSs / PEI composite layers, and the middle three layers from bottom to top are 100nm BaTiO3 NPs / PEI composite layer, 200nm BaTiO3 NPs / PEI composite layer and 500nm BaTiO3 NPs / PEI composite layer, which can be simplified as BLMSB model, wherein B represents BNNSs / PEI composite layer, L represents 500nm BaTiO3 NPs / PEI composite layer, M represents 200nm BaTiO3 NPs / PEI composite layer, and S represents 100nm BaTiO3 NPs / PEI composite layer.

[0112] The preparation method of the above-mentioned five-layer structure PEI-based composite film material comprises the following steps:

[0113] (1) 1.5g of h-BN powder is dispersed in 150ml of N,N-dimethylformamide, ultrasonic treatment is performed for 9h, the mixed solution is centrifuged at 3500r / min for 9min, and finally the precipitate is vacuum dried at 75℃ for 13h to obtain BNNSs.

[0114] (2) 0.0258g of BNNSs and 2.4g of PEI are dispersed in 24ml of NMP, at this time the volume of BNNSs accounts for 0.5vol% of the volume of PEI, ultrasonic treatment is performed for 2.5h, magnetic stirring is performed at a speed of 370r / min and a temperature of 43℃ for 9h, to prepare a BNNSs / PEI mixed solution A;

[0115] 0.3553g of 500nm BaTiO3 NPs and 1.2g of PEI are dispersed in 12ml of NMP, at this time the volume of 500nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic treatment is performed for 5.5h, magnetic stirring is performed at a speed of 510r / min and a temperature of 48℃ for 12.5h, to prepare a 500nm BaTiO3 NPs / PEI mixed solution X1;

[0116] 0.3553g of 200nm BaTiO3 NPs and 1.2g of PEI are dispersed in 12ml of NMP, at this time the volume of 200nm BaTiO3 NPs accounts for 5vol% of the volume of PEI, ultrasonic treatment is performed for 5.5h, magnetic stirring is performed at a speed of 510r / min and a temperature of 48℃ for 12.5h, to prepare a 200nm BaTiO3 NPs / PEI mixed solution X2;

[0117] 0.3553 g of 100 nm BaTiO3 NPs and 1.2 g of PEI were dispersed in 12 ml of NMP. At this time, the volume of 100 nm BaTiO3 NPs accounted for 5 vol% of the volume of PEI. The mixture was sonicated for 5.5 h and then magnetically stirred at 510 r / min and 48 °C for 12.5 h to prepare 100 nm BaTiO3 NPs / PEI mixed solution X3.

[0118] (3) Set the casting machine temperature to 182℃, adjust the scraper speed to 13mm / s, and control the scraper height to 6μm. Mixed solution A was first cast on a glass plate and then vacuum dried at 62°C for 17 min in a vacuum drying oven to form a film. Mixed solution X3 was second cast on the glass plate after the first film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X2 was third cast on the glass plate after the second film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution X1 was fourth cast on the glass plate after the third film formation and then vacuum dried at 62°C for 27 min in a vacuum drying oven to form a film. Mixed solution A was fifth cast on the glass plate after the fourth film formation and then vacuum dried at 62°C for 37 min in a vacuum drying oven to form a film. Finally, the five-layer PEI-based composite film material BLMSB was vacuum dried at 75°C for 7 h to allow the solvent to evaporate and then peeled off from the glass plate to obtain the five-layer PEI-based composite film material.

[0119] (4) The prepared five-layer PEI-based composite thin film material BLMSB was subjected to cross-sectional SEM testing, such as... Figure 13 As shown in the figure, the composite thin film material obtained in this embodiment exhibits a distinct five-layer structure with good interface bonding and no structural defects, and a total thickness of approximately 30 μm. The two outer layers are PEI composite layers containing sheet-like BNNSs, while the three middle layers, from bottom to top, are a PEI composite layer containing small-diameter 100 nm BaTiO3 NPs, a PEI composite layer containing medium-diameter 200 nm BaTiO3 NPs, and a PEI composite layer containing large-diameter 500 nm BaTiO3 NPs, each with a thickness of approximately 6 μm.

[0120] (5) Cut the prepared thin film sample into a rectangle of 12mm×15mm to prepare a diffracted film, deposit a gold electrode with a diameter of 2mm, and then test the ferroelectric performance at a temperature of 150℃, and calculate the energy storage performance accordingly. Figure 14The electric hysteresis loop of the five-layer PEI-based composite film material BLMSB of the present example was measured at 150°C, and based on the electric hysteresis loop, the effective energy storage density of the five-layer PEI-based composite film material BLMSB of the present example was calculated to be 7.36 J / cm 3 at an electric field intensity of 450 MV / m, and the energy storage efficiency was 83.12%. Table 1 shows the energy storage performance of the five-layer PEI-based composite film material BLMSB of the present example at 150°C.

[0121] Table 1 Energy storage performance of the five-layer PEI-based composite film material at 150°C

[0122]

[0123] As can be seen from Table 1, the five-layer PEI-based composite film material has excellent high-temperature energy storage performance. The outer layers are BNNSs / PEI composite layers, and the middle three layers are 100 nm BaTiO3 NPs / PEI composite layers, 200 nm BaTiO3 NPs / PEI composite layers, and 500 nm BaTiO3 NPs / PEI composite layers from bottom to top, respectively. The five-layer gradient structure PEI-based composite film material obtained an effective energy storage density of 7.36 J / cm 3 and an energy storage efficiency of 83.12% at a temperature of 150°C and an electric field intensity of 450 MV / m. The five-layer PEI-based composite film material obtained an energy storage density of 6.45-7.36 J / cm 3 and an energy storage efficiency of 73.72%-83.53% at a temperature of 150°C and an electric field intensity of 450 MV / m. Through the above examples, it can be found that the macroscopic interface structure design combining thermal conduction / insulation and polarization can synergistically improve the energy storage density and energy storage efficiency at high temperature. The maximum use temperature of commercial bidirectional stretched polypropylene (BOPP) in short-term operation is < 105°C, and in long-term operation it is ≤ 85°C. Therefore, in order to install a BOPP film capacitor in the power inverter of a hybrid electric vehicle, a cooling system must be used to reduce the environmental temperature from 140°C to 70°C. This not only brings additional weight, volume, and energy consumption, but also reduces the reliability and efficiency of the equipment. The five-layer PEI-based composite film prepared by the present application, which has excellent high-temperature energy storage performance, is expected to replace BOPP to prepare film capacitors, in order to meet the practical application requirements of high-temperature energy storage composite films in special fields such as aerospace and new energy electric vehicles.

Claims

1. A method for preparing a five-layer PEI-based composite thin film with high-temperature energy storage performance, characterized in that, Includes the following steps: Step 1: Two-dimensional boron nitride nanosheets and PEI are uniformly dispersed in N-methyl-2-pyrrolidone, with the two-dimensional boron nitride nanosheets accounting for 0.5% of the PEI volume, to obtain mixture A; 500 nm BaTiO3 nanoparticles and PEI are uniformly dispersed in N-methyl-2-pyrrolidone to obtain mixture B; 200 nm BaTiO3 nanoparticles and PEI are uniformly dispersed in N-methyl-2-pyrrolidone to obtain mixture C; 100 nm BaTiO3 nanoparticles and PEI are uniformly dispersed in N-methyl-2-pyrrolidone to obtain mixture D, with the three types of BaTiO3 nanoparticles accounting for 5% of the corresponding PEI volume; Step 2: Cast the mixture A, then vacuum dry it at 57-63 °C for 15-20 min. Repeat this process three times on the formed BNNSs / PEI composite layer under the following six different conditions, drying it under vacuum at 57-63 °C for 25-30 min after each casting to form the second, third, and fourth composite layers sequentially: In the first case, all solutions use solution B; in the second case, all solutions use solution C; in the third case, all solutions use solution D; in the fourth case, solutions B, D, and B are used in sequence; in the fifth case, solutions D, B, and D are used in sequence; and in the sixth case, solutions D, C, and B are used in sequence. Step 3: The surface of the fourth composite layer is cast for the fifth time with mixed liquid A, and then vacuum dried at 57~63 ℃ for 35~40 min to form BNNSs / PEI composite layer. Finally, it is vacuum dried at 72~78 ℃ for 5~8 h to obtain a five-layer PEI-based composite film with high temperature energy storage performance. Step 2: First, set the temperature of the casting machine to 175~183 ℃, adjust the doctor blade speed to 9~14 mm / s, and the doctor blade height to 5~7μm, and then perform all casting processes.

2. The method for preparing the five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 1, characterized in that, Step 1 uses a liquid phase exfoliation method to prepare two-dimensional boron nitride nanosheets in N,N-dimethylformamide.

3. The method for preparing the five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 2, characterized in that, Step 1: Disperse 1.5 g of hexagonal boron nitride powder in 150 ml of N,N-dimethylformamide, sonicate for 6-12 h, centrifuge at 3000-3600 r / min for 8-10 min, and finally vacuum dry the precipitate at 70-80 ℃ for 12-15 h to obtain two-dimensional boron nitride nanosheets.

4. The method for preparing the five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 1, characterized in that, In step 1, the ratio of PEI to organic solvent in mixtures A, B, C, and D is 1 g: 10 ml.

5. The method for preparing the five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 1, characterized in that, In step 1, when dispersing PEI and two-dimensional boron nitride nanosheets, the mixture is first sonicated for 2-3.5 h, and then magnetically stirred at a speed of 350-420 r / min and a temperature of 40-45 ℃ for 8-11 h to obtain mixture A.

6. The method for preparing the five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 1, characterized in that, In step 1, when dispersing PEI and the corresponding BaTiO3 nanoparticles, the mixture was first sonicated for 4 to 6.5 h, and then magnetically stirred at a rotation speed of 475 to 535 r / min and a temperature of 43 to 53 °C for 11 to 13.5 h to obtain mixture B, mixture C and mixture D.

7. A five-layer PEI-based composite film with high-temperature energy storage performance obtained by the preparation method of the five-layer PEI-based composite film with high-temperature energy storage performance according to any one of claims 1 to 6.

8. The five-layer PEI-based composite thin film with high-temperature energy storage performance according to claim 7, characterized in that, The composite film has a thickness of 25~35 μm and exhibits a strength of 6.45~7.36 J / cm² at a temperature of 150 ℃ and an electric field strength of 450 MV / m. 3 It has an energy storage density and an energy storage efficiency of 73.72%~83.53%.

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