CN108587007B - A kind of laminated construction ferroelectric polymers based dielectric film, and its preparation method and application - Google Patents

Abstract

The present invention relates to a kind of laminated construction ferroelectric polymers based dielectric film, and its preparation method and application.The film have at least one first dielectric layer and with alternately stacked second dielectric layer of first dielectric layer, first dielectric layer contains vinylidene fluoride-hexafluoropropylene copolymer P (VDF-co-HFP) and sheet Al₂O₃, wherein with volume percentage, the proportion of the two is (100-x) %P (VDF-co-HFP)-x%Al₂O₃, 0 < x≤7, second dielectric layer contains ferroelectric polymers.Laminated construction ferroelectric polymers based dielectric film of the invention has high breakdown field strength, high energy storage density and a high energy storage efficiency, and leadless environment-friendly, with excellent energy-storage property, be suitable for high density energy storage field.

Description

A kind of ferroelectric polymer-based dielectric thin film with laminated structure, its preparation method and use

technical field

The invention relates to a ferroelectric polymer-based dielectric thin film with a laminated structure, a preparation method and application thereof, and belongs to the field of dielectric materials.

Background technique

Compared with electrochemical-based energy storage devices such as supercapacitors and lithium batteries, energy storage devices based on dielectric capacitors have the advantages of higher power density, lower loss, and higher operating voltage. Therefore, dielectric capacitors are not only important basic electronic components, but also widely used in basic energy storage devices in electronic power systems and energy systems.

The energy storage density of current commercial polymer-based dielectric materials such as BOPP is only ~2 J/cm ³ , which is one to two orders of magnitude lower than that of electrochemical capacitors or batteries. The low energy storage density of polymers has become a bottleneck for its further development and application. Ceramic dielectrics have a large dielectric constant and high breakdown field strength, but compared with polymer film dielectrics, their breakdown field strength is still not high enough, and they are bulky and inflexible, making ceramic dielectrics in some applications The field is limited, but the polymer-based dielectric film has the characteristics of flexibility and small size, which can meet the requirements of future device miniaturization and integration.

In the case of traditional high-dielectric ceramic materials and single polymer film materials, there are several disadvantages in the development of high-power and large-capacity capacitors. Dielectric material. Therefore, exploring composite dielectrics with high energy storage density is a research hotspot in this field.

Energy storage densities greater than 2 J/cm ³ of commercial BOPP films have been achieved in polymer-based dielectric films. Among them, representative materials such as: P(VDF-co-CTFE) film prepared by ZC Zhang et al. by solution method, the material has an energy storage density of about 7-10J/cm ³ at a field strength of 400MV/m, MRGadinski and B .Chu et al. respectively increased the breakdown field strength of such films to 600-700MV/m by uniaxial stretching method, and at the same time increased the energy storage density to about 20J/cm ³ . However, the solution method used in the preparation of these materials is not suitable for large-scale production. Therefore, the development of polymer-based dielectric thin film dielectric materials with high breakdown field strength, high energy storage density and easy production has become an urgent task in this field.

Contents of the invention

The problem to be solved by the invention

The object of the present invention is to provide a ferroelectric polymer-based dielectric thin film with laminated structure, its preparation method and application. The ferroelectric polymer-based dielectric thin film of the invention has high breakdown field strength, high energy storage density and high energy storage efficiency, and the preparation method is simple and feasible, and is convenient for production.

solutions to problems

The present invention provides a ferroelectric polymer-based dielectric thin film with a stacked structure, which is characterized in that the thin film has at least one first dielectric layer and second dielectric layers alternately stacked with the first dielectric layer, and the first The dielectric layer contains vinylidene fluoride-hexafluoropropylene copolymer P(VDF-co-HFP) and lamellar Al ₂ O ₃ , wherein, in terms of volume percentage, the ratio of the two is (100-x)%P( VDF-co-HFP)–x%Al ₂ O ₃ , 0<x≤7, the second dielectric layer contains a ferroelectric polymer, preferably a vinylidene fluoride-hexafluoropropylene copolymer P(VDF-co-HFP ).

According to the ferroelectric polymer-based dielectric thin film with a stacked structure of the present invention, the thickness of the thin film is 5-30 μm, preferably 6-20 μm.

According to the laminated ferroelectric polymer-based dielectric thin film of the present invention, in the first dielectric layer, x is 1-7, preferably 3-7.

According to the laminated ferroelectric polymer-based dielectric thin film of the present invention, the shape of the Al ₂ O ₃ is a two-dimensional sheet.

According to the ferroelectric polymer-based dielectric thin film with a stacked structure of the present invention, the particle size of the Al ₂ O ₃ is nanoscale, preferably 20-100 nm, more preferably 20-60 nm.

The present invention also provides a method for preparing a laminated ferroelectric polymer-based dielectric film according to the present invention, comprising the following steps:

Step 1), mixing the lamellar Al ₂ O ₃ and the vinylidene fluoride-hexafluoropropylene copolymer P(VDF-co-HFP) in an organic solvent according to the ratio to obtain an electrospinning solution 1; The ferroelectric polymer is dissolved in an organic solvent to obtain an electrospinning solution 2;

Step 2), the electrospinning solution 1 and the electrospinning solution 2 are alternately subjected to high-voltage electrospinning to obtain a non-woven spinning body with a laminated structure;

Step 3), hot-pressing the non-woven spinning body of the laminated structure, naturally cooling to room temperature, and then quenching to obtain a laminated ferroelectric polymer-based dielectric film.

According to the preparation method of the laminated ferroelectric polymer-based dielectric film of the present invention, in the step 2), the positive and negative voltage difference of high-voltage electrospinning is ≥6.5kV, the rotating speed of the collecting wheel is ≥270 rpm, and the solution is advanced Speed ≥ 1mL/h.

According to the preparation method of the laminated structure ferroelectric polymer-based dielectric film of the present invention, in the step 3), the non-woven spinning body is hot-pressed at 190-220° C., under a pressure of 400-600 dpi for 30- 70 minutes.

According to the preparation method of the laminated ferroelectric polymer-based dielectric film of the present invention, the non-woven spinning body is hot-pressed, cooled to room temperature naturally, and kept at 190-240° C. for 1-20 minutes, Quenching was performed at 0°C.

A use of the laminated ferroelectric polymer-based dielectric thin film according to the present invention in electrical components.

The effect of the invention

The laminated ferroelectric polymer-based dielectric film provided by the present invention has high breakdown field strength, high energy storage density and high energy storage efficiency, is lead-free and environmentally friendly, and has excellent energy storage performance, and is suitable for high-density storage can. At the same time, the laminated ferroelectric polymer-based dielectric film provided by the present invention has a small dielectric loss, and is a kind of electrical component that can be applied to various electrical components, such as embedded capacitors, electrostatic energy storage components, pulse power materials in components and other fields.

Description of drawings

Figure 1 Schematic diagram of the structure of a polymer-based dielectric capacitor;

Fig. 2 schematic diagram of multilayer structure of polymer-based dielectric film;

Inorganic matter Al prepared in Fig. ₃ embodiment 1 The SEM figure of O ₃ ;

The XRD figure of the inorganic substance _Al2O3 prepared in Fig. ₄ embodiment 1;

The cross-sectional SEM figure of the polymer-based dielectric film prepared in Fig. 5 embodiment 1;

The energy storage performance diagram of the polymer-based dielectric film prepared in Fig. 6 embodiment 1 and comparative example 1;

The energy storage performance diagram of the polymer-based dielectric film prepared in Fig. 7 embodiment 2 and comparative example 1;

The energy storage performance diagram of the polymer-based dielectric film prepared in Fig. 8 embodiment 3 and comparative example 1;

Fig. 9 is a diagram of the energy storage properties of the polymer-based dielectric films prepared in Example 4 and Comparative Example 1.

Explanation of reference signs

1: Dielectric capacitor; 2: Electrode; 3: Polymer-based dielectric film;

31: first dielectric layer; 32: second dielectric layer.

Detailed ways

The present invention provides a ferroelectric polymer-based dielectric film with a stacked structure, the film has at least one first dielectric layer and second dielectric layers alternately stacked with the first dielectric layer, the first dielectric layer contains bias Vinyl fluoride-hexafluoropropylene copolymer P(VDF-co-HFP) and lamellar Al ₂ O ₃ , wherein, in terms of volume percentage, the ratio of the two is (100-x)%P(VDF-co- HFP)—x% Al ₂ O ₃ , 0<x≦7, the second dielectric layer contains a ferroelectric polymer, preferably contains vinylidene fluoride-hexafluoropropylene copolymer P(VDF-co-HFP).

Compared with other ferroelectric polymers, such as PVDF, the P(VDF-co-HFP) produced by the copolymerization of monomer hexafluoropropylene HFP and vinylidene fluoride VDF has a narrower and longer hysteresis loop and is a fluorine-containing Excellent alternative to ferroelectric polymer PVDF.

The invention improves the breakdown environment inside the ferroelectric polymer by adding lamellar Al ₂ O ₃ , and can achieve the purpose of increasing the breakdown field strength of the ferroelectric polymer. The breakdown field strength of the ferroelectric polymer-based dielectric film of the present invention at room temperature is greater than or equal to 600kV/mm, and when x is preferably 1≤x≤7, the ferroelectric polymer-based dielectric film of the present invention is at room temperature The breakdown field strength is ≥700kV/mm. At the same time, the lamellar Al ₂ O ₃ can also regulate the stacked structure of the film, which can achieve the purpose of improving energy storage efficiency and energy storage density.

The second dielectric layer of the present invention contains a ferroelectric polymer, or a combination of a ferroelectric polymer and other resin compositions, and the ferroelectric polymer can be any ferroelectric polymer that can be used in dielectric thin films in the art. The second dielectric layer contains, for example: vinylidene fluoride-hexafluoropropylene copolymer P (VDF-co-HFP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), poly Styrene (PS), polysulfone (PSF), polyarylsulfone (PASF), polyethersulfone (PES), polypropylene (PP), polyethylene (PE), cross-linked polyethylene (PEX), polyethylene terephthalic acid Polyethylene glycol ester (PET), polycarbonate (PC), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyamide (PA), polyimide (PI), polyether Imide (PEI), cyano resin, etc., or the above ferroelectric polymers or resin copolymers or combinations thereof. Further, the second dielectric layer preferably contains vinylidene fluoride-hexafluoropropylene copolymer P (VDF-co-HFP), which is beneficial to obtain a dielectric film with higher energy storage density and energy storage efficiency.

The laminated ferroelectric polymer-based dielectric film of the present invention, wherein, the thickness of the film is 5-30 μm, preferably 6-20 μm, and the thickness range is compatible with the mature film preparation equipment and technology in the existing industry better.

The ferroelectric polymer-based dielectric film of the present invention has multiple layers, may have one or more than one first dielectric layer, and one or more than one second dielectric layer, and the first dielectric layer and the second dielectric layer are stacked alternately. Specifically, the stacked structure shown below can be cited:

first dielectric layer/second dielectric layer.../second dielectric layer/first dielectric layer, or

second dielectric layer/first dielectric layer.../second dielectric layer/first dielectric layer, or

Second dielectric layer/first dielectric layer.../first dielectric layer/second dielectric layer.

There is no special requirement on the upper limit of the number of dielectric layers, as long as the production process can be realized. When the number of dielectric layers is greater than or equal to 3, the multilayer structure can effectively improve the energy storage efficiency of the thin film.

Wherein, there is no special requirement on the thickness of each dielectric layer, which may be the same or different. The ratio of the total thickness of the first dielectric layer to the total thickness of the second dielectric layer is 1:12˜1:1, and the thickness ratio can effectively enhance the breakdown resistance performance of the film.

In the laminated ferroelectric polymer-based dielectric thin film of the present invention, in the first dielectric layer, x is 1-7, preferably 3-7, and within the above range, the ferroelectric polymer has good flexibility. It should be noted that, in the present invention, the contents of Al ₂ O ₃ in different first dielectric layers may be the same or different. From the viewpoint of the convenience of industrial production, it is preferable that the content of Al ₂ O ₃ in each first dielectric layer is the same.

In the laminated ferroelectric polymer-based dielectric thin film of the present invention, in the thin film, the shape of the Al ₂ O ₃ is preferably a two-dimensional sheet, which is conducive to improving the breakdown field strength of the thin film, Thereby increasing the energy storage density. The particle size of the Al ₂ O ₃ is preferably nanoscale, more preferably 20-100nm, and even more preferably 20-60nm. Nanoparticles are more likely to be uniformly distributed in the polymer electrolyte layer and improve the quality of the film. By adjusting the spinning process and the hot pressing process, the lamination distribution state of the inorganic Al ₂ O ₃ in the ferroelectric polymer can be regulated, so as to realize the tunability of the energy storage density and the breakdown field strength.

The energy storage density of the laminated ferroelectric polymer-based dielectric film at room temperature is greater than 5 J/cm ³ , preferably 15-35 J/cm ³ . The dielectric constant of the polymer added with inorganic substance Al ₂ O ₃ is lower than that of the pure ferroelectric polymer, while the dielectric loss remains basically unchanged, that is, the dielectric loss is below 0.05 at 1KHz.

The present invention also provides a method for preparing the laminated ferroelectric polymer-based dielectric film according to the present invention, which includes the following steps:

Step 1), mixing the lamellar Al ₂ O ₃ and the vinylidene fluoride-hexafluoropropylene copolymer P(VDF-co-HFP) in an organic solvent according to the ratio to obtain an electrospinning solution 1; The ferroelectric polymer is dissolved in an organic solvent to obtain an electrospinning solution 2;

Step 2), the electrospinning solution 1 and the electrospinning solution 2 are alternately subjected to high-voltage electrospinning to obtain a non-woven spinning body with a laminated structure;

Step 3), hot-pressing the non-woven spinning body of the laminated structure, naturally cooling to room temperature, and then quenching to obtain a laminated ferroelectric polymer-based dielectric film.

In the method for preparing a laminated structure ferroelectric polymer-based dielectric thin film of the present invention, the lamellar Al ₂ O ₃ can be prepared by the following steps: subjecting an alkaline solution with a pH ≥ 8 containing Al salt to hydrothermal reaction to obtain lamellar AlOOH, and then heat-treat the AlOOH above 400°C.

According to the above _- mentioned preparation method of lamellar _Al2O3 , wherein, the pH of the alkaline solution is preferably >8, and this pH value range is conducive to the formation of the two-dimensional morphology of the inorganic substance AlOOH, and is more conducive to Two-dimensional flake Al ₂ O ₃ is obtained. However, the temperature and time of the hydrothermal reaction have no obvious effect on the morphology of AlOOH, for example, it is carried out at 150-240° C. and kept for 2-24 hours. After the hydrothermal reaction, the reaction product was washed to neutrality and dried. The AlOOH thermally decomposes to generate Al ₂ O ₃ after heat treatment higher than 400°C, and different phases of Al ₂ O ₃ will be generated depending on the heat treatment temperature, but the crystal phase of Al ₂ O ₃ is not particularly specified in the present invention. limit.

The preparation method of the lamination structure ferroelectric polymer-based dielectric thin film adopts the electrospinning method, and the method is beneficial to prepare the lamination structure polymer-based thin film.

In the present invention, as long as it can meet the requirements of the fiber diameter, there is no special requirement for the electrospinning method, and it can be the commonly used electrospinning method in this field. Specifically, in the present invention, vinylidene fluoride- Hexafluoropropylene copolymer P(VDF-co-HFP) and/or Al ₂ O ₃ is dissolved in a suitable solvent to prepare a solution with a certain concentration. According to the above-mentioned spinning sequence, the two kinds of spinning solutions are alternately spun by electrospinning technology to obtain a dielectric layer with a laminated structure formed by nanofibers, and the shape of the fibers is a non-woven spinning body.

In the method for preparing a laminated ferroelectric polymer-based dielectric film of the present invention, in the step 1), in order to mix uniformly, stir and mix for 12-24 hours.

The method for preparing a laminated ferroelectric polymer-based dielectric film of the present invention, wherein the organic solvent in step 1) is acetone, N,N-dimethylformamide (DMF) or N,N-dimethylformamide Diacetamide (DMA). In order to obtain a high-quality spinning body, preferably, the ratio of acetone to N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) is 1:4˜6:7.

The method for preparing a laminated structure ferroelectric polymer-based dielectric film of the present invention, wherein, in the step 2), the positive and negative voltage difference of the high-voltage electrospinning is ≥ 6.5kV, the rotating speed of the collecting wheel is ≥ 270 rpm, and the solution Propel speed ≥ 1mL/h. The ratio of solute (grams) to solution (ml) ranges from 1:4.3 to 1:7.9. According to the concentration of the spinning solution, select the appropriate specific spinning process parameters, such as voltage difference, solution advancing speed, etc.

In the present invention, the above-mentioned multi-layer spinning body is hot-pressed to form a whole, and a ferroelectric polymer-based dielectric film with a laminated structure is obtained.

The method for preparing a laminated structure ferroelectric polymer-based dielectric film of the present invention, wherein, in the step 3), the non-woven spinning body is hot-pressed at 190-220° C. under a pressure of 400-600 dpi for 30 ~70 minutes. This is beneficial to ensure good interfacial bonding between the spinning bodies of each layer, and avoid large deformation of each layer.

The method for preparing a laminated structure ferroelectric polymer-based dielectric film of the present invention, wherein the non-woven spinning body is hot-pressed, cooled to room temperature naturally, and then the film is kept at 190-240°C for 1-20 Minutes later, quenching at 0 °C is beneficial for the polymer to obtain better energy storage density.

The invention also provides a use of the ferroelectric polymer-based dielectric thin film with a laminated structure in the invention in electrical components. The electrical components are embedded capacitors, electrostatic energy storage components or pulse power components.

Example

Example 1

AlCl ₃ 6H ₂ O, NaOH, and NH ₃ OH were prepared in deionized water to form a 1M solution, and then the mixed solution of NaOH and NH ₃ OH was gradually and slowly dropped into the AlCl ₃ solution until the pH of the solution was After = 8, the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, kept in an oven at 200°C for 17 hours, and the precipitate was obtained after natural cooling, and the precipitate was repeatedly washed with deionized water and ethanol until the pH value It is neutral, and the precipitate after drying is treated at a high temperature of 650°C to obtain a two-dimensional flake nano-powder Al ₂ O ₃ , according to 99vol%P(VDF-co-HFP)–1vol%Al ₂ O ₃ (x =1) Dosing, wherein each gram of solid powder corresponds to a ratio of 5 milliliters of a mixed solvent, using acetone and N,N-dimethylacetamide (DMA) as a mixed solvent, stirring for 10 hours to make spinning solution 1 for later use, The ratio of acetone and DMA in the mixed solvent is 2:3.

According to the ratio of 5 ml of mixed solvent per gram of solid powder, P(VDF-co-HFP) was added to the mixed solvent of acetone and N,N-dimethylformamide (DMF), and stirred for 12 hours to make spinning Liquid 2 is for later use, the ratio of acetone and DMF in the mixed solvent is 2:3.

A homogeneous spun body of polymer nanofilaments was prepared by high-voltage electrospinning. The parameters of the high-voltage electrospinning are: positive and negative voltage difference 6.5kV; roller speed 285 rpm; solution propulsion speed 1mL per hour; spinning solution 1 and spinning solution 2 alternately spinning, spinning solution 1 The silk layer is the contact electrode layer, and the spinning layer of the spinning solution 2 is the non-contact electrode layer, finally forming a three-layer spinning lamination.

After spinning, the three spinning layers were hot-pressed at 200° C. and 500 dpi for 60 minutes, and then cooled down to room temperature naturally. The hot-pressed film was kept at 240° C. for 10 minutes and then quenched at 0° C. to obtain a ferroelectric polymer-based dielectric film, denoted as film 1.

The thickness of the prepared film 1 is about 9.4 μm, and the properties of the polymer-based dielectric film at 25° C. are: the breakdown field strength is 745 kV/mm, the energy storage efficiency is 70%, and the energy storage density is about 22.7 J/mm cm ³ .

Example 2

AlCl ₃ 6H ₂ O, NaOH, and NH ₃ OH were prepared in deionized water to form a 1M solution, and then the mixed solution of NaOH and NH ₃ OH was gradually and slowly dropped into the AlCl ₃ solution until the pH of the solution was After = 9.2, the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, kept in an oven at 200°C for 20 hours, and the precipitate was obtained after natural cooling, and the precipitate was repeatedly washed with deionized water and ethanol until the pH value It is neutral, and the precipitate after drying is treated at a high temperature of 600°C to obtain a two-dimensional flake nano-powder Al ₂ O ₃ , according to 99vol%P(VDF-co-HFP)–1vol%Al ₂ O ₃ (x =1) Dosing, wherein each gram of solid powder corresponds to a ratio of 5 milliliters of a mixed solvent, using acetone and N,N-dimethylformamide (DMF) as a mixed solvent, stirring for 10 hours to make spinning solution 1 for later use, The ratio of acetone and DMF or DMA in the mixed solvent is 2:3.

According to the ratio of 5 ml of mixed solvent per gram of solid powder, P(VDF-co-HFP) was added to the mixed solvent of acetone and N,N-dimethylformamide (DMF), and stirred for 12 hours to make spinning Liquid 2 is for later use, the ratio of acetone and DMF in the mixed solvent is 2:3.

A homogeneous spun body of polymer nanofilaments was prepared by high-voltage electrospinning. The parameters of the high-voltage electrospinning are: positive and negative voltage difference 6.5kV; roller speed 285 rpm; solution propulsion speed 1mL per hour; spinning solution 1 and spinning solution 2 alternately spinning, spinning solution 1 The silk layer is the contact electrode layer, the spinning layer of the spinning solution 2 is the non-contact electrode layer, and finally a 5-layer spinning laminate is formed.

After spinning, the three spinning layers were hot-pressed at 210° C. and 520 dpi for 60 minutes, and then cooled down to room temperature naturally. The hot-pressed film was kept at 240° C. for 10 minutes and then quenched at 0° C. to obtain a ferroelectric polymer-based dielectric film, denoted as film 2 .

The thickness of the prepared film 2 is about 10.69 μm, and the properties of the polymer-based dielectric film at 25°C are: the breakdown field strength is 837kV/mm, the energy storage efficiency is 63%, and the energy storage density is 26J/cm ³ .

Example 3

AlCl ₃ 6H ₂ O, NaOH, and NH ₃ OH were prepared in deionized water to form a 1M solution, and then the mixed solution of NaOH and NH ₃ OH was gradually and slowly dropped into the AlCl ₃ solution until the pH of the solution was After = 8.6, the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, kept in an oven at 200°C for 19 hours, and the precipitate was obtained after natural cooling, and the precipitate was repeatedly washed with deionized water and ethanol until the pH value It is neutral, and the precipitate after drying is treated at a high temperature of 650°C to obtain a two-dimensional flake nano-powder Al ₂ O ₃ , according to 97vol%P(VDF-co-HFP)–3vol%Al ₂ O ₃ (x =3) Dosing, wherein each gram of solid powder corresponds to a ratio of 5 milliliters of mixed solvent, using acetone and N,N-dimethylformamide (DMF) as mixed solvent, stirring for 15 hours to make spinning solution 1 for later use, The ratio of acetone and DMF in the mixed solvent is 2:3.

According to the ratio of 5 ml of mixed solvent per gram of solid powder, P(VDF-co-HFP) was added to the mixed solvent of acetone and N,N-dimethylformamide (DMF), and stirred for 12 hours to make spinning Liquid 2 is for later use, the ratio of acetone and DMF in the mixed solvent is 2:3.

A homogeneous spun body of polymer nanofilaments was prepared by high-voltage electrospinning. The parameters of the high-voltage electrospinning are: positive and negative voltage difference 6.7kV; roller speed 300 rpm; solution propulsion speed 1ml per hour; spinning solution 1 and spinning solution 2 alternate spinning, spinning solution 1 The silk layer is a non-contact electrode layer, and the spinning layer of the spinning solution 2 is a contact electrode layer, finally forming a three-layer spinning laminate.

After spinning, the three spinning layers were hot-pressed at 205° C. and 510 dpi for 60 minutes, and then cooled down to room temperature naturally. The hot-pressed film was kept at 240° C. for 10 minutes and then quenched at 0° C. to obtain a ferroelectric polymer-based dielectric film, denoted as film 3 .

The thickness of the prepared film 3 is about 10.83 μm, and the properties of the polymer-based dielectric film at 25°C are: the breakdown field strength is 732kV/mm, the energy storage efficiency is 71%, and the energy storage density is 23.8J/cm ³ .

Example 4

AlCl ₃ 6H ₂ O, NaOH, and NH ₃ OH were prepared in deionized water to form a 1M solution, and then the mixed solution of NaOH and NH ₃ OH was gradually and slowly dropped into the AlCl ₃ solution until the pH of the solution was After = 8.6, the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, kept in an oven at 200°C for 19 hours, and the precipitate was obtained after natural cooling, and the precipitate was repeatedly washed with deionized water and ethanol until the pH value It is neutral, and the precipitate after drying is treated at a high temperature of 650°C to obtain a two-dimensional flake nano-powder Al ₂ O ₃ , according to 93vol%P(VDF-co-HFP)–7vol%Al ₂ O ₃ (x =7) Dosing, wherein each gram of solid powder corresponds to a ratio of 5 milliliters of mixed solvent, using acetone and N,N-dimethylformamide (DMF) as mixed solvent, stirring for 15 hours to make spinning solution 1 for later use, The ratio of acetone and DMF in the mixed solvent is 2:3.

According to the ratio of 5 ml of mixed solvent per gram of solid powder, P(VDF-co-HFP) was added to the mixed solvent of acetone and N,N-dimethylformamide (DMF), and stirred for 12 hours to make spinning Liquid 2 is for later use, the ratio of acetone and DMF in the mixed solvent is 2:3.

A homogeneous spun body of polymer nanofilaments was prepared by high-voltage electrospinning. The parameters of the high-voltage electrospinning are: positive and negative voltage difference 6.7kV; roller speed 300 rpm; solution propulsion speed 1ml per hour; spinning solution 1 and spinning solution 2 alternate spinning, spinning solution 1 The silk layer is a non-contact electrode layer, and the spinning layer of the spinning solution 2 is a contact electrode layer, finally forming a three-layer spinning laminate.

After spinning, the three spinning layers were hot-pressed at 200°C and 500dpi for 30 minutes, and then cooled down to room temperature naturally. The hot-pressed film was kept at 240° C. for 10 minutes and then quenched at 0° C. to obtain a ferroelectric polymer-based dielectric film, denoted as film 4 .

The thickness of the prepared film 4 is about 14 μm, and the properties of the polymer-based dielectric film at 25° C. are: the breakdown field strength is 879 kV/mm, the energy storage efficiency is 71%, and the energy storage density is 29.6 J/cm ³ .

Comparative example 1

After mixing the purchased P(VDF-co-HFP) powder according to 5 ml of mixed organic solvent (a mixture of acetone and dimethylformamide (DMF)) per gram of solute, stir at room temperature for 12-24 hours to make it Fully dissolve. A homogeneous spun body of polymer nanofilaments was prepared by high-voltage electrospinning. The parameters of the high-voltage electrospinning are: the positive and negative voltage difference is 6 kV; the rotation speed of the roller is 300 rpm, and the solution advancing speed is 1 mL per hour. After spinning, the spinning layer was hot-pressed at 200° C. and 500 dpi for 60 minutes, and then cooled down to room temperature naturally. The hot-pressed film was kept at 240° C. for 10 minutes and then quenched at 0° C. to obtain a ferroelectric polymer-based dielectric film, denoted as film 4 .

The thickness of the prepared film 4 is about 10 μm, and the properties of the polymer-based dielectric film at 25°C are as follows: the breakdown field strength is 400KV/mm, the energy storage efficiency is 56.7%, and the energy storage density is 7.8J/ ^cm3 .

Performance Testing

Metal round electrodes were prepared by vacuum evaporation on sample films 1-4, and their properties were tested.

Dielectric properties: Tested with an impedance analyzer (Agilent, E4990A, USA)

Breakdown field strength and ferroelectric hysteresis loop: The ferroelectric tester (Radiant Tech., Precision Premier II) was used for testing, and the energy storage density and energy storage efficiency were calculated by the hysteresis loop.

Claims (12)

1. a kind of laminated construction ferroelectric polymers based dielectric film, which is characterized in that the film have at least one first Dielectric layer and with alternately stacked second dielectric layer of first dielectric layer, first dielectric layer contains inclined fluorine second Alkene-hexafluoropropylene copolymer P (VDF-co-HFP) and sheet Al₂O₃, wherein with volume percentage, the proportion of the two is (100-x) %P (VDF-co-HFP)-x%Al₂O₃, 0 < x≤7,

Second dielectric layer contains vinylidene fluoride-hexafluoropropylene copolymer P (VDF-co-HFP),

The Al₂O₃Partial size be 20~100nm.

2. laminated construction ferroelectric polymers based dielectric film according to claim 1, which is characterized in that the film With a thickness of 5~30 μm.

3. laminated construction ferroelectric polymers based dielectric film according to claim 2, which is characterized in that the film With a thickness of 6~20 μm.

4. described in any item laminated construction ferroelectric polymers based dielectric films according to claim 1~3, which is characterized in that In first dielectric layer, x is 1~7.

5. laminated construction ferroelectric polymers based dielectric film according to claim 4, which is characterized in that first electricity In dielectric layer, x is 3~7.

6. described in any item laminated construction ferroelectric polymers based dielectric films according to claim 1~3, which is characterized in that The Al₂O₃Pattern be two-dimensional sheet.

7. described in any item laminated construction ferroelectric polymers based dielectric films according to claim 1~3, which is characterized in that The Al₂O₃Partial size be 20~60nm.

8. a kind of preparation side of laminated construction ferroelectric polymers based dielectric films described in any item according to claim 1~7 Method, which comprises the steps of:

Step 1), by the sheet Al₂O₃Exist according to the ratio with the vinylidene fluoride-hexafluoropropylene copolymer P (VDF-co-HFP) It is mixed in organic solvent, obtains electrostatic spinning liquid 1；The ferroelectric polymers is dissolved in organic solvent, obtains electrostatic spinning Liquid 2；

Step 2), by the electrostatic spinning liquid 1 and the alternately high-voltage electrostatic spinning of the electrostatic spinning liquid 2, obtain lamination knot The non-woven fabric-like spinning body of structure；

The non-woven fabric-like spinning body of the laminated construction is carried out hot pressing by step 3), is carried out cold quenching after cooled to room temperature, is obtained To laminated construction ferroelectric polymers based dielectric film.

9. the preparation method of laminated construction ferroelectric polymers based dielectric film according to claim 8, which is characterized in that In the step 2), positive and negative voltage difference >=6.5kV of high-voltage electrostatic spinning, revolving speed >=270 rev/min of collecting wheel, solution pushed away Into speed >=1mL/h.

10. the preparation method of laminated construction ferroelectric polymers based dielectric film according to claim 8 or claim 9, feature Be, in the step 3), by the non-woven fabric-like spinning body under 190~220 DEG C, 400~600dpi pressure hot pressing 30~ 70 minutes.

11. the preparation method of laminated construction ferroelectric polymers based dielectric film according to claim 8 or claim 9, feature It is, the non-woven fabric-like spinning body is subjected to hot pressing, after cooled to room temperature, keeps the temperature 1~20 minute at 190~240 DEG C Afterwards, in 0 DEG C of progress cold quenching.

12. a kind of laminated construction ferroelectric polymers based dielectric films described in any item according to claim 1~7 are in electrical member Purposes in part.