M-coated SiO2 / PVDF composite dielectric film and preparation method thereof

Abstract

The invention relates to the technical field of energy storage materials, in particular to an M-coated SiO2 / PVDF composite dielectric film and a preparation method thereof.The preparation method comprises the steps that ethyl orthosilicate, copper nitrate trihydrate or silver nitrate, polyvinylpyrrolidone (PVP) and hexadecyl trimethyl ammonium bromide serve as raw materials, and an improved # imgabs0 # method is adopted for preparing Cu-coated SiO2 core-shell structure filler; pVDF is dissolved in dimethylformamide, the prepared M-coated SiO2 core-shell structure filler is added, the M-coated SiO2 / PVDF composite dielectric film is prepared through a solution tape casting method, and M is Cu or Ag. Compared with the prior art, the metal particles are coated with the SiO2 through the self-made composite filler, the phenomenon of high dielectric loss caused by agglomeration of the metal particles or incompatibility of the metal particles and a PVDF film interface can be effectively avoided, and the composite material has a high dielectric constant due to the excellent conductivity of metal.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage materials, in particular to a M@SiO 2 / PVDF composite dielectric film and preparation method thereof. Background Art

[0002] As people's demand for energy increases, the storage technology of electric energy is receiving more and more attention. Compared with energy storage devices such as electrochemical capacitors and fuel cells, dielectric capacitors have extremely high power density. This is because dielectric capacitors store and release energy by controlling the polarization and depolarization process of dielectric materials through an external electric field. The relaxation time of polarization and depolarization is very short, so the charging and discharging process of dielectric materials is much faster than that of batteries. However, the energy storage density of dielectric capacitors is relatively low.

[0003] Polymer materials have the advantages of good flexibility, easy processing, low dielectric loss, and good self-healing properties. They are often used as dielectric materials, but their dielectric constants are often low, so adding conductive materials to polymer materials is the mainstream method today. Metal materials have a higher dielectric constant, but they are also accompanied by higher dielectric losses. Directly adding conductive materials to polymers will form an uneven interface area, affecting its conductive mechanism. Summary of the invention

[0004] The purpose of the present invention is to provide a M@SiO 2 / PVDF composite dielectric film and preparation method thereof, Cu coated SiO 2 Can bring additional Cu / SiO 2 and SiO 2 / PVDF interface, maintaining a high interface polarization, thereby improving the dielectric constant of the composite material, and the metal particles are not easy to aggregate after being coated with silica, and the filler is evenly dispersed in the PVDF matrix, so that the composite material maintains a low dielectric loss. The preparation method specifically includes using an improved Preparation of Cu@SiO 2 Core-shell fillers were added to PVDF and Cu@SiO was prepared by solution casting process. 2 / PVDF composite dielectric film.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The first aspect of the present invention provides a M@SiO 2 A method for preparing a / PVDF composite dielectric film comprises the following steps:

[0007] S1: Using tetraethyl orthosilicate, copper nitrate trihydrate or silver nitrate, polyvinyl pyrrolidone (PVP), and hexadecyltrimethylammonium bromide as raw materials, using improved Preparation of Cu@SiO 2 Core-shell structure fillers;

[0008] S2: Dissolve PVDF in dimethylformamide and add the prepared M@SiO 2 Core-shell structure filler, M@SiO prepared by solution casting method 2 / PVDF composite dielectric film, M is Cu or Ag.

[0009] Furthermore, in S1, the specific steps include:

[0010] S1-1: Weigh copper nitrate trihydrate and polyvinyl pyrrolidone (PVP), place them in anhydrous ethanol, and disperse them by ultrasonication to obtain a metal-containing solution; mix hexadecyltrimethylammonium bromide, ammonia water, and anhydrous ethanol with the assistance of ultrasound to ensure that the pH is within the range of 9 to 10 to obtain an ammonia-containing solution; add the metal-containing solution to the ammonia-containing solution, and continue mixing;

[0011] S1-2: dilute ethyl orthosilicate with anhydrous ethanol, and inject it into the solution being mixed in S1-1 using an injection pump, stir, separate the solid in the reaction solution by centrifugation, and wash with deionized water and anhydrous ethanol;

[0012] S1-3: The obtained solid is placed in an oven and dried at 60-90°C for 12 h. The obtained solid is ground to obtain Cu@SiO 2 Core-shell structure filler.

[0013] Further, in S1-1, the mass ratio of the copper nitrate trihydrate to polyvinyl pyrrolidone (PVP) is 1:8;

[0014] The mass ratio of the silver nitrate to polyvinyl pyrrolidone (PVP) is 1:3.8.

[0015] In S1-1, the ultrasonic dispersion time is 30 min.

[0016] Furthermore, in S1-2, the anhydrous ethanol dilutes the ethyl orthosilicate in a ratio of 10:1.

[0017] Furthermore, in S1-2, a microinjection pump is used to inject the diluted ethyl orthosilicate into the solution being mixed in S1-1, and the liquid injection flow rate is controlled at 0.5 mL / min, and stirring is performed for 48 hours.

[0018] Furthermore, in S2, the specific steps include:

[0019] S2-1: PVDF powder was mixed with dimethylformamide (DMF) solvent and ultrasonicated until the solution became clear. M@SiO 2 Core-shell structure filler, stirring;

[0020] S2-2: Pour the liquid obtained in S2-1 onto a clean glass plate, apply the solution evenly using a scraper-type applicator, and then dry it to obtain a flat, regular-shaped, and uniformly thick M@SiO 2 / PVDF composite dielectric film.

[0021] Further, S2-1 specifically includes the following process: mixing PVDF powder with dimethylformamide (DMF) solvent, ultrasonically treating for 30 min until the solution becomes clear, adding M@SiO 2 Core-shell structure filler, stirred at 25°C, 400-600 rpm / min for 24 h;

[0022] The Cu@SiO 2 The mass ratio of the core-shell structure filler to the PVDF powder is 1:9.

[0023] Furthermore, in S2-2, the drying condition is: placing in a vacuum oven at 90° C. and drying for 2 to 4 hours.

[0024] Furthermore, by coating SiO with Cu or Ag 2 Bringing additional Cu / SiO 2 and SiO 2 / PVDF interface or Ag / SiO 2 and SiO 2 / PVDF interface, maintaining a high interface polarization, thereby improving the dielectric constant of the composite material; the metal particles Cu and Ag are not easy to aggregate after being coated with silica; the filler is evenly dispersed in the PVDF matrix, so that the composite material maintains a low dielectric loss.

[0025] The second aspect of the present invention provides a M@SiO prepared by the above method. 2 / PVDF composite dielectric film.

[0026] Among them, the obtained Cu@SiO 2 / PVDF composite dielectric film, thickness is 10-30μm, dielectric constant is 16.4 at 1000Hz, dielectric loss is 0.046 at 1000Hz.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention uses a self-made composite filler to coat the metal particles onto SiO 2Internally, it can effectively avoid the high dielectric loss caused by the agglomeration of metal particles or the incompatibility of metal particles with the PVDF film interface. The excellent conductivity of the metal also makes the composite material have a higher dielectric constant. 2 The core-shell material has good dielectric properties, the selected preparation process is relatively simple, and the PVDF-based material has good processability, so it can realize the preparation of flexible dielectric capacitors of any size and shape, and has great application potential in the field of dielectric energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a preparation flow chart of Example 1 of the present invention;

[0030] Figure 2 The Cu@SiO obtained in Example 1 of the present invention 2 Scanning electron micrograph of filler;

[0031] Figure 3 The Cu@SiO obtained in Example 1 of the present invention 2 Scanning electron microscopy image of the surface of / PVDF composite material

[0032] Figure 4 1 is a graph showing the dielectric constant and dielectric loss of Example 1, Example 2, and Comparative Example 1 of the present invention as a function of frequency. DETAILED DESCRIPTION

[0033] In general, the present invention discloses a method of adding Cu@SiO 2 Polyvinylidene fluoride (PVDF) based dielectric film with core-shell structure filler and preparation method thereof. Figure 1 The preparation method specifically comprises using an improved The method is to slowly inject tetraethyl orthosilicate into a mixed solution of alkaline copper nitrate trihydrate and polyvinyl pyrrolidone for coating, and then wash and centrifuge to obtain a solid product, which is then dried and ground to obtain Cu@SiO 2 The core-shell filler is added into a clear PVDF solution dissolved in DMF organic solvent, the filler is dispersed by stirring, and the uniformly dispersed solution is evenly spread on a glass plate by a doctor blade coater using a solution casting process, and then dried to obtain Cu@SiO 2 / PVDF composite dielectric film. The present invention uses a self-made composite filler to coat the metal particles onto SiO 2 Internally, the high dielectric loss caused by the agglomeration of metal particles or the incompatibility of metal particles with the PVDF film interface can be effectively avoided. The excellent electrical conductivity of the metal also makes the composite material have a higher dielectric constant. 2The dielectric constant of the PVDF / PVDF composite dielectric film reaches 16.4 at 1000Hz, which is 1.89 times that of the film without filler. The dielectric loss is only 0.046 at 1000Hz.

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0035] Example 1

[0036] 1) Weigh 0.3g copper nitrate trihydrate and 2.4g polyvinyl pyrrolidone, place in 100mL anhydrous ethanol, and disperse by ultrasound for 30min. Mix 1g hexadecyltrimethylammonium bromide, 20mL ammonia water and 80mL anhydrous ethanol with the aid of ultrasound to ensure that the pH is in the range of 9 to 10. Add the metal-containing solution to the ammonia-containing solution.

[0037] 2) Dilute 3 ml of ethyl orthosilicate to 30 ml with anhydrous ethanol and inject it into the mixing solution using a microinjection pump. The liquid injection flow rate is controlled at 0.5 mL / min and stirred for 48 hours.

[0038] 3) The solid in the reaction solution was separated by centrifugation and washed three times with deionized water and anhydrous ethanol. The obtained solid was placed in an oven and dried at 80°C for 12 hours. The obtained solid was ground into Cu@SiO 2 filler.

[0039] 4) 0.1g Cu@SiO 2 Filler: 0.9 g PVDF powder was mixed with 9 g dimethylformamide solvent, and ultrasonic treatment was performed for 30 min until there was no solid agglomerate in the solution, and then stirred at 25° C. and 500 rpm / min for 24 h.

[0040] 5) Pour the obtained liquid onto a clean glass plate, apply the solution evenly using a scraper-type film applicator, and then place it in a vacuum oven at 90°C and dry it for 4 hours to obtain a Cu@SiO film with a thickness of 10 to 30 μm. 2 / PVDF composite materials.

[0041] Figure 2 The Cu@SiO obtained in Example 1 of the present invention 2 Scanning electron micrograph of filler, Figure 2 It can be seen that the filler has a spherical morphology, and the metal particles are 2 Evenly distributed in the ball, the filler particle size is 300-500nm; Figure 3 The Cu@SiO obtained in Example 1 of the present invention 2Scanning electron microscope image of the surface of / PVDF composite material, Figure 3 It can be seen that the filler is evenly distributed in the PVDF film without obvious aggregation.

[0042] Example 2

[0043] This example is carried out in a similar manner to Example 1, except that in step 1), the copper nitrate trihydrate used is replaced by 0.63 g of silver nitrate, and the solid obtained in step 3) is Ag@SiO 2 Filler. The final composite material is named Ag@SiO 2 / PVDF.

[0044] Comparative Example 1

[0045] 1) Mix 1 g of PVDF powder with 10 g of dimethylformamide solvent, treat with ultrasound for 30 min until there is no solid agglomerate in the solution, and stir at 25° C. and 500 rpm / min for 24 h.

[0046] 2) Pour the obtained liquid onto a clean glass plate, apply the solution evenly using a doctor blade applicator, and then place it in a vacuum oven at 90° C. for 4 h to obtain a PVDF dielectric film.

[0047] The dielectric properties of the dielectric composite materials prepared in Examples 1 and 2 and the dielectric film prepared in Comparative Example 1 were tested. Aluminum electrodes were first sputtered onto both sides of the film using a magnetron sputtering instrument, and then the dielectric properties of the film with electrodes were tested using an impedance analyzer.

[0048] Figure 4 The dielectric constant and dielectric loss of the dielectric composite materials prepared in Example 1 and Example 2 and the dielectric film prepared in Comparative Example 1 are plotted as a function of frequency. The dielectric constant of Example 1 is 16.4 at 1000 Hz, and the dielectric constant of Comparative Example 1 is 8.6 at 1000 Hz. After adding the modified filler, the dielectric constant is increased due to the interface polarization between the filler and the matrix. 5 The dielectric loss is slightly different below Hz, and the loss after adding fillers is slightly lower than that without adding fillers. At this frequency, the main loss is conductivity loss. 5 Above Hz, the main loss is polarization loss. The addition of fillers leads to interface polarization, which causes an increase in dielectric loss at high frequencies.

[0049] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a M@SiO2 / PVDF composite dielectric film, characterized in that: The following steps are involved: S1: Using tetraethyl orthosilicate, copper nitrate trihydrate or silver nitrate, polyvinyl pyrrolidone (PVP), and hexadecyltrimethylammonium bromide as raw materials, using improved Method for preparing Cu@SiO2 core-shell structure filler; S2: Dissolve PVDF in dimethylformamide, add the prepared M@SiO2 core-shell structure filler, and prepare the M@SiO2 / PVDF composite dielectric film by solution casting method, where M is Cu or Ag.

2. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 1, characterized in that: In S1, the specific steps include: S1-1: Weigh copper nitrate trihydrate and polyvinyl pyrrolidone (PVP), place them in anhydrous ethanol, and disperse them by ultrasonication to obtain a metal-containing solution; mix hexadecyltrimethylammonium bromide, ammonia water, and anhydrous ethanol with the assistance of ultrasound to ensure that the pH is within the range of 9 to 10 to obtain an ammonia-containing solution; add the metal-containing solution to the ammonia-containing solution, and continue mixing; S1-2: dilute ethyl orthosilicate with anhydrous ethanol, and inject it into the solution being mixed in S1-1 using an injection pump, stir, separate the solid in the reaction solution by centrifugation, and wash with deionized water and anhydrous ethanol; S1-3: The obtained solid is placed in an oven and dried at 60-90° C. for 12 hours. The obtained solid is ground to obtain a Cu@SiO2 core-shell structure filler.

3. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 2, characterized in that: In S1-1, the mass ratio of copper nitrate trihydrate to polyvinyl pyrrolidone (PVP) is 1:8; The mass ratio of the silver nitrate to polyvinyl pyrrolidone (PVP) is 1:3.

8. In S1-1, the ultrasonic dispersion time is 30 min.

4. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 2, characterized in that: In S1-2, the anhydrous ethanol dilutes ethyl orthosilicate in a ratio of 10:

1.

5. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 2, characterized in that: In S1-2, a microinjection pump is used to inject the diluted ethyl orthosilicate into the solution being mixed in S1-1. The liquid injection flow rate is controlled at 0.5 mL / min and stirred for 48 hours.

6. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 1, characterized in that: In S2, the specific steps include: S2-1: PVDF powder was mixed with dimethylformamide (DMF) solvent, and ultrasonic treatment was performed until the solution became clear, and M@SiO2 core-shell structure filler was added and stirred; S2-2: Pour the liquid obtained in S2-1 onto a clean glass plate, apply the solution evenly using a scraper-type applicator, and then dry it to obtain a flat, regularly shaped, and uniformly thick M@SiO2 / PVDF composite dielectric film.

7. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 6, characterized in that: In S2-1, the following process is specifically included: PVDF powder is mixed with dimethylformamide (DMF) solvent, ultrasonic treatment is performed for 30 min until the solution becomes clear, M@SiO2 core-shell structure filler is added, and stirring is performed at 25°C and 400-600 rpm / min for 24 h; The mass ratio of the M@SiO2 core-shell structure filler to the PVDF powder is 1:

9.

8. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 1, characterized in that: In S2-2, the drying conditions are: placing in a vacuum oven at 90°C and drying for 2 to 4 hours.

9. The method for preparing a M@SiO2 / PVDF composite dielectric film according to claim 1, characterized in that: By coating SiO2 with Cu or Ag, additional Cu / SiO2 and SiO2 / PVDF interfaces or Ag / SiO2 and SiO2 / PVDF interfaces are created, maintaining a high interface polarization, thereby improving the dielectric constant of the composite material. The metal particles Cu or Ag are not easy to aggregate after being coated with silica, and the filler is evenly dispersed in the PVDF matrix, so that the composite material maintains a low dielectric loss.

10. A M@SiO2 / PVDF composite dielectric film prepared by the method according to any one of claims 1 to 9.

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