CN109461577B - Preparation method and application of dielectric energy storage composite material - Google Patents

Abstract

The present invention provides a preparation method and application of a dielectric energy storage composite material. The preparation method of the present invention comprises: coating a solution containing an inorganic dielectric material and a polymer on a substrate, allowing the inorganic dielectric material to settle under vibration conditions, and then heating and curing to form; peeling the cured film from the substrate, and then laminating the two films with the side in contact with the substrate as the laminating surface, and then hot pressing to obtain a dielectric energy storage composite material with a sandwich structure. The method of the present invention does not need to prevent the sedimentation process of the dielectric material in the solution as in the traditional preparation method. Instead, it can utilize the natural sedimentation of the dielectric material to produce a transition layer with a gradient change of the dielectric material, which not only simplifies the preparation process steps, but also reduces the macroscopic physical interface, and can avoid the problem of too low breakdown voltage caused by excessive differences between the materials between the layers, and effectively improves the performance of the dielectric energy storage composite material.

Description

A kind of preparation method and application of dielectric energy storage composite material

technical field

The invention relates to the field of materials, in particular to a preparation method and application of a dielectric energy storage composite material.

Background technique

In recent years, with the vigorous development of the semiconductor industry, electronic products are also developing in the direction of miniaturization and intelligence. Capacitors are one of the most important components in electronic products, and their performance determines the quality and efficacy of electronic products to a certain extent. is an important influence.

Currently, commonly used dielectric materials include traditional inorganic dielectric materials and polymer resin materials, both of which have a wide range of applications. However, the application of inorganic dielectric materials is limited due to their low breakdown strength; while polymer resin materials are easier to process and have good compatibility with organic circuit boards, their low dielectric constants also limit their applications. its scope of use.

In order to meet the characteristics of high dielectric constant, breakdown resistance, and easy processing at the same time, dielectric composite materials composed of polymers and inorganic dielectric materials have emerged as the times require. The dielectric composite materials with laminated/multi-layered materials can exhibit excellent properties such as high dielectric constant, low dielectric loss, high breakdown field strength, and high energy storage density.

In the existing methods, multi-layer high-dielectric films are mostly prepared by casting or hot pressing, that is, a laminate/multi-layer dielectric composite material is formed by pouring layer by layer of materials, although the performance of the prepared dielectric composite material is It is better, but the preparation process is complicated, and the settling and agglomeration of the high dielectric filler should be avoided as much as possible during the preparation process, and the operation is complicated.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a preparation method of a dielectric energy storage composite material. The method of the present invention has the advantages of simple process, small difference between material layers, and high breakdown field strength.

The second object of the present invention is to provide a dielectric energy storage composite material.

The third object of the present invention is to provide an application of a dielectric energy storage composite material.

In order to realize the above-mentioned purpose of the present invention, the following technical solutions are specially adopted:

A dielectric energy storage composite material, the dielectric energy storage composite material has a three-layer structure, comprising: upper and lower polymer layers, and an inorganic dielectric material-polymer composite layer intermediate layer; the dielectric energy storage The composite material is formed by thermocompression of two double-layer materials, wherein each double-layer material includes a polymer layer and an inorganic dielectric material-polymer composite layer.

Preferably, in the dielectric energy storage composite material of the present invention, the inorganic dielectric material is a nanometer inorganic dielectric material; more preferably, the nanometer inorganic dielectric material includes: nanowires, nanosheets, and nanometers At least one of particles; more preferably, the inorganic nano-dielectric material includes: at least one of barium titanate, strontium titanate, barium strontium titanate, and titanium dioxide nanomaterials.

Preferably, in the dielectric energy storage composite material of the present invention, the upper polymer layer comprises: polyvinylidene fluoride, epoxy resin, polyvinylidene fluoride copolymer, polypropylene, polyester, polyurea and polyimide at least one of the amine layers; and/or, the lower polymer layer comprises: polyvinylidene fluoride, epoxy resin, polyvinylidene fluoride copolymer, polypropylene, polyester, polyurea and polyimide layers at least one; more preferably, the material of the upper polymer layer is the same as that of the lower polymer layer.

At the same time, the present invention also provides a method for preparing a dielectric energy storage composite material, comprising: coating a solution containing an inorganic dielectric material and a polymer on a substrate, and making the inorganic dielectric material settle under vibration conditions, Then heat curing and molding; peeling the cured film from the substrate, bonding the two films with the side in contact with the substrate as the bonding surface, and hot pressing to obtain a dielectric energy storage composite material with a sandwich structure.

Preferably, in the preparation method of the present invention, the inorganic dielectric material is subjected to surface modification and then dispersed in a solution.

Preferably, in the preparation method of the present invention, the step of modifying the surface of the inorganic dielectric material includes: modifying the surface of the inorganic dielectric material with dopamine.

Preferably, in the preparation method of the present invention, the inorganic dielectric material is a nano-inorganic dielectric material; more preferably, the nano-inorganic dielectric material includes: at least one of nanowires, nanosheets, and nanoparticles more preferably, the inorganic nano-dielectric material includes at least one of barium titanate, strontium titanate, barium strontium titanate, and titanium dioxide nanomaterials.

Preferably, in the preparation method of the present invention, the polymer comprises: at least one of polyvinylidene fluoride, epoxy resin, polyvinylidene fluoride copolymer, polypropylene, polyester, polyurea and polyimide kind.

Meanwhile, the present invention also provides the application of the dielectric energy storage composite material of the present invention in the preparation of capacitors or electrostatic energy storage devices.

Further, the present invention also provides a device or device comprising the dielectric energy storage composite material of the present invention.

Compared with the prior art, the beneficial effects of the present invention are:

In the present invention, by adopting the method of short-time vibration and sedimentation, the inorganic dielectric material with higher density can be settled in the solution to obtain the inorganic dielectric material-polymer composite layer distributed on the bottom surface of the film, and after heating and curing, A "1.5" layer dielectric composite film is obtained, and finally a three-layer dielectric composite film with a sandwich structure is prepared by a hot pressing process. Therefore, compared with the traditional process, the method of the present invention does not need to prevent the sedimentation process of the dielectric material in the solution, but can generate a transition layer with gradient changes of the dielectric material through the natural sedimentation of the dielectric material, which not only simplifies the The preparation process steps can also avoid problems such as too low breakdown voltage caused by excessive differences between the materials between the layers, and effectively improve the performance of the dielectric energy storage composite material.

Further, since the side of the "1.5" layer of dielectric composite film attached to the substrate is a flat and smooth surface, and the surface of the side in contact with the air has a unit cell structure, this method can ensure that the three-layer dielectric composite film is formed by lamination. The physical interface between the two sides and the two sides of the composite film are flat, which is beneficial to further improve the breakdown voltage.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required to be used in the description of the embodiments or the prior art.

FIG. 1 is a schematic diagram of the synthesis process of the dielectric energy storage composite material of the present invention.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

The preparation method of the dielectric energy storage composite material provided by the present invention is a new preparation route that is different from the traditional layer-by-layer pouring to form a laminated structure. Compared with the traditional method, it can not only simplify the process steps, but also The electrical properties of the dielectric energy storage composites can also be improved.

Specifically, the preparation method of the present invention mainly uses the following raw materials:

(1) Nano inorganic dielectric materials;

In the present invention, the raw material form of the raw nano inorganic dielectric material is at least one of nanowires, nanosheets, and nanoparticles;

Specifically, in the present invention, the inorganic nano-dielectric materials used include: barium titanate nanowires, barium titanate nanosheets, barium carbonate nanoparticles; and strontium titanate nanowires, strontium titanate nanosheets, and strontium titanate nanoparticles ; barium strontium titanate nanowires, barium strontium titanate nanoparticles, barium strontium titanate nanosheets; and at least one of titanium dioxide nanowires, titanium dioxide nanosheets, and titanium dioxide nanoparticles;

The above raw materials can be commercially available raw materials, or can be prepared by conventional methods in the art.

(2) Polymer

Mainly include: at least one of polyvinylidene fluoride, epoxy resin, polyvinylidene fluoride copolymer, polypropylene, polyester, polyurea and polyimide.

(3) Solvent

As a raw material for dispersing nanometer inorganic dielectric materials and dissolving polymers, in the present invention, NMP (N-methylpyrrolidone) is preferably used as a solvent. Due to its high boiling point, NMP can slow down the curing time and is the most important material in the composite film. The barium titanate nanowires provide sufficient time to settle.

Further, the specific steps of preparing the dielectric energy storage composite material with the above raw materials in the present invention include the following processes:

(1) Surface modification of nano-inorganic dielectric materials

In order to improve the dispersibility of the nano-inorganic dielectric material in the polymer matrix, in the present invention, the surface of the inorganic nano-dielectric material is firstly modified and coated. dispersibility in the material.

Specifically, it can be done as follows:

After cleaning the nano inorganic dielectric material, disperse it in dopamine hydrochloride solution, then adjust the pH to about 8.5 with ammonia water, after stirring and mixing, mix it with deionized water and ethanol solution, centrifuge, and then vacuum dry to obtain the surface Dopamine-coated nano-inorganic dielectric materials.

(2) Synthesis of dielectric energy storage composites

First, the surface-modified inorganic dielectric material and polymer are weighed according to the required weight ratio, added to the solvent, fully stirred, and ultrasonically treated to obtain a uniformly dispersed inorganic dielectric material and a polymer dissolved in it. solution.

Then, referring to Fig. 1, a specific molding process including casting, vibration, peeling and hot pressing is performed. The specific process can refer to Fig. 1 (the following steps (i)-(iv) correspond to the 4 processes in Fig. 1 respectively) .

(i) After cleaning the substrate (preferably a glass substrate), place it on the vibration platform, and then apply the solution on the substrate (the solution can be poured on one end of the substrate first, and then spread the solution on the substrate with a doctor blade). on, and ensure that the thickness of the liquid film is uniform);

(ii) Turn on the vibration platform, adjust the amplitude to a lower level as much as possible, adjust the vibration frequency to a higher level, and mechanically vibrate, so that the inorganic dielectric material can settle naturally in the polymer matrix;

After shaking for a period of time (preferably 10 min), the shaking is stopped, and the substrate is transferred to a vacuum oven to dry, remove the residual solvent, and cure to form a film.

This step is the main innovation of the present invention, which is different from the operation of superimposing hot pressing after layer-by-layer casting in the traditional method, and controlling the sedimentation of the dielectric material in the casting process. In the present invention, following the process of using a concrete vibrator to drive out air bubbles in the concrete construction process to make the concrete compact, a micro-vibration platform is used to make inorganic fillers with slightly higher density (dopamine surface-modified nano-inorganic dielectrics) material) settling.

After a short time of shaking and sedimentation, a nano-dielectric material-polymer composite layer distributed on the bottom surface of the film can be obtained (the solvent gradually evaporates during this process). Moreover, in this layer, the density of the inorganic nano-dielectric material changes in a gradient (closer to the substrate, the higher the density); at the same time, the upper layer of the formed film is a polymeric dielectric material layer that contains almost no inorganic nano-dielectric material.

It is further cured by vacuum heating to form a double-layer structure film of polymer layer-nano-dielectric material/polymer composite layer.

(iii) peel off the formed film from the substrate, and then attach the two double-layer structure films, and the bonding surface is the smooth side of the corresponding film in contact with the substrate (because this surface is in direct contact with the substrate, the formed The surface is a smooth surface, and this can also make the physical interface formed after further bonding smooth, which is conducive to the improvement of breakdown voltage), that is, the side where the inorganic nano-dielectric material is deposited is bonded;

Wherein, the raw material inorganic nano-dielectric material and raw material polymer used in the preparation of the two double-layer structure films can be independently and optionally the same or different.

(iv) Finally, hot pressing is performed to obtain a dielectric energy storage composite material having a three-layer sandwich structure of polymer-inorganic nano-dielectric material/polymer composite layer-polymer.

In the dielectric energy storage composite material prepared by the above method of the present invention, the upper and lower layers are pure polymer base layers that hardly contain nano-dielectric materials, which are used as breakdown layers; and the middle layer is nano-dielectric material/polymer composite layer (formed by the lamination of two composite layers) as a high dielectric layer.

Since the polymer base layer and the inorganic nano-dielectric material/polymer base layer are produced by natural sedimentation, a transition layer is generated, and the nanowire concentration has a gradual gradient. Therefore, the composite film prepared by the method of the present invention can effectively avoid the layer The difference between the materials is too large and the breakdown voltage is too low.

At the same time, compared with the traditional three-layer separate preparation process, the present invention reduces the preparation steps, reduces the macroscopic physical interface (optimized from the original two macroscopic interfaces to one layer of macroscopic interface), and reduces the preparation or transfer process at the same time. influence of environmental factors.

The breakdown voltage of the obtained dielectric composite material is 200-300 V/um using the traditional composite method. The method of the invention can not only simplify the experimental steps, but also can increase the breakdown voltage of the dielectric composite material to more than 350-400V/um. At the same time, on the basis of keeping the dielectric constant constant, the energy storage density and the breakdown electric field have a square relationship, so the energy storage density of the dielectric composite material of the present invention can be increased by at least 78% on the basis of the original dielectric composite material.

The dielectric energy storage composite material prepared by the above method, because of its good electrical properties, can be used for the preparation of devices such as capacitors or electrostatic energy storage devices, and then used in various devices.

Example 1 Preparation of barium titanate nanowire composite three-layer dielectric energy storage composite material

_1. Preparation BaTiO3 nanowires were prepared by secondary hydrothermal growth as the filler component of multilayer high dielectric films. Specifically include:

(i) Add the TiO ₂ nanopowder into the NaOH solution, stir it for 2 hours, mix it into a polytetrafluoroethylene-lined hydrothermal kettle, and tighten, and place it in a 200°C environment for hydrothermal reaction for 72 hours to obtain a white powder Na ₂ Ti ₃ O ₇ , filtered and cleaned with deionized water, and dried at 90°C.

(ii) The obtained Na ₂ Ti ₃ O ₇ powder was slowly added to the Ba(OH) ₂ ·8H ₂ O solution and stirred for 2 h, and finally placed in a polytetrafluoroethylene-lined hydrothermal kettle and tightened. The reaction was carried out for 24 h and cooled to room temperature to obtain barium titanate nanowires.

_2. Surface modification of BaTiO3 nanowires by dopamine

The BaTiO3 nanowires _were washed and dispersed in dopamine hydrochloride solution, and the pH was adjusted to 8.5 with weak ammonia water, then stirred at 60 °C for 17 h, and finally mixed with deionized water and ethanol solution for several times, and vacuum-dried at 80 °C for 24 h to obtain Surface-modified dopamine _- coated BaTiO3 nanowires.

_3. Preparation of dopamine BaTiO3 nanowires/PVDF-based composite films

Weigh the required ratio of dopamine BaTiO ₃ nanowires and PVDF-based polymer materials, disperse/dissolve the two materials in NMP solvent, stir for 24 h and ultrasonicate for 2 h to obtain a uniformly dispersed dopamine BaTiO ₃ nanowire/PVDF-based composite solution .

After cleaning the glass substrate, place it on a clean micro-vibration platform. Then, pour the dopamine BaTiO ₃ nanowire/PVDF-based composite solution on one end of the glass substrate, and gently scratch the surface of the solution with a scraper with a fixed thickness to ensure the thickness of the liquid film. uniform;

Then, open the micro-vibration platform, adjust the amplitude to be as small as possible, increase the vibration frequency, and mechanically vibrate for 10 minutes to make the BaTiO ₃ nanowires settle naturally;

After 10 min, the glass substrate was transferred to a vacuum oven at 40 °C, dried for 24 hours to drive off the residual solvent and cured into a film.

The obtained film was peeled off from the glass surface, and two prepared dopamine BaTiO ₃ nanowire/PVDF-based composite films were taken, and the two films were attached to one side of the glass substrate for relative bonding, and then put into a mold and hot-pressed at 200 °C. A dopamine-modified barium titanate nanowire composite film with a sandwich structure is obtained.

Example 2 Preparation of strontium titanate nanoparticles composite three-layer dielectric energy storage composite material

Strontium titanate nanoparticles (can be prepared according to conventional methods, for details, refer to the prior art CN102139916A, CN104003437A, etc.) are dispersed in dopamine hydrochloride solution, and the pH is adjusted to 8.5 with weak ammonia water, then stirred at 60 ° C for 17 hours, and finally used separately. The ionized water and ethanol solution were mixed and centrifuged for several times, and then vacuum-dried at 80 °C for 24 h to obtain dopamine-coated strontium titanate nanoparticles after surface modification.

Then, the required ratio of dopamine strontium titanate nanoparticles and epoxy resin-based polymer materials were weighed, and the two materials were dispersed/dissolved in NMP solvent, stirred for 24 hours, and sonicated for 4 hours to obtain uniformly dispersed dopamine strontium titanate. Nanoparticle/epoxy resin based composite solution.

After cleaning the glass substrate, place it on a clean micro-vibration platform. Then, pour the dopamine strontium titanate nanoparticle/epoxy resin-based composite solution on one end of the glass substrate, and gently scratch the surface of the solution with a scraper with a fixed thickness to ensure that The thickness of the liquid film is uniform;

Then, open the micro-vibration platform, adjust the amplitude to be as small as possible, increase the vibration frequency, and mechanically vibrate for 15 minutes to make the strontium titanate nanoparticles settle naturally;

Then, the glass substrate was transferred to a 45 °C vacuum oven, dried for 24 h to drive off the residual solvent and cured into a film.

The obtained film was peeled off from the glass surface, and two prepared dopamine strontium titanate nanoparticles/epoxy resin-based composite films were taken, and the two films were attached to one side of the glass substrate and were placed in a mold for heating at 220°C. Press molding to obtain a dopamine-modified strontium titanate nanoparticle composite film with a sandwich structure.

Example 3 Preparation of barium strontium titanate nanosheet composite three-layer dielectric energy storage composite material

The strontium barium titanate nanosheets (which can be prepared according to conventional methods, see the prior art CN103523824A, etc.) are dispersed in dopamine hydrochloride solution, and the pH is adjusted to 8.5 with weak ammonia water, then stirred at 60° C. for 17 hours, and finally deionized The water and ethanol solution were mixed and centrifuged for several times, and then vacuum-dried at 80°C for 24 hours to obtain dopamine-coated barium strontium titanate nanosheets after surface modification.

Then, the required ratio of dopamine barium strontium titanate nanosheets and PI-based polymer materials were weighed, and the two materials were dispersed/dissolved in NMP solvent, stirred for 24 hours, and sonicated for 4 hours to obtain uniformly dispersed dopamine barium strontium titanate. Nanosheet/PI-based composite solution.

After cleaning the glass substrate, place it on a clean micro-vibration platform. Then, pour the dopamine barium strontium titanate nanosheet/PI-based composite solution on one end of the glass substrate, and gently scratch the surface of the solution with a scraper with a fixed thickness to ensure that the liquid The film thickness is uniform;

Then, open the micro-vibration platform, adjust the amplitude to be as small as possible, increase the vibration frequency, and mechanically shake for 15 minutes to make the barium strontium titanate nanosheets settle naturally;

Then, the glass substrate was transferred to a 45 °C vacuum oven, dried for 24 h to drive off the residual solvent and cured into a film.

The obtained film was peeled off from the glass surface, and two prepared dopamine barium strontium titanate nanosheets/PI-based composite films were taken, and the two films were attached to one side of the glass substrate, and were placed in a mold for hot pressing at 220°C forming, to obtain a dopamine-modified barium strontium titanate nanosheet composite film with a sandwich structure.

Although specific embodiments of the present invention have been illustrated and described, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications as fall within the scope of this invention be included in the appended claims.

Claims (9)

1. a preparation method of a dielectric energy storage composite material, is characterized in that, comprises: the solution containing inorganic dielectric material and polymer is coated on the substrate, under vibration condition, makes inorganic dielectric material settle, then heat curing molding; The film obtained by curing is peeled off from the substrate, and two of the films are bonded with the surface in contact with the substrate as the bonding surface, and hot-pressed to obtain a dielectric energy storage composite material with a sandwich structure. 2 . The preparation method according to claim 1 , wherein the preparation method further comprises the step of dispersing the inorganic dielectric material in a solution after surface modification. 3 . 3 . The preparation method according to claim 2 , wherein the step of modifying the surface of the inorganic dielectric material comprises: modifying the surface of the inorganic dielectric material with dopamine. 4 . 4. The preparation method according to claim 1, wherein the inorganic dielectric material is a nanometer inorganic dielectric material. 5 . The preparation method according to claim 4 , wherein the nano-inorganic dielectric material comprises at least one of nanowires, nanosheets, and nanoparticles. 6 . 6 . The preparation method according to claim 4 , wherein the nano inorganic dielectric material comprises: at least one of barium titanate, strontium titanate, barium strontium titanate, and titanium dioxide nanomaterials. 7 . 7. The preparation method according to claim 1, wherein the polymer comprises: polyvinylidene fluoride, epoxy resin, polyvinylidene fluoride copolymer, polypropylene, polyester, polyurea and polyimide at least one of amines. 8. The application of the dielectric energy storage composite material prepared by the method of any one of claims 1 to 7 in the preparation of capacitors or electrostatic energy storage devices. 9. A device or device comprising a dielectric energy storage composite prepared by the method of any one of claims 1-7.

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