A flexible variable capacitor and its fabrication method

Abstract

A flexible variable capacitor and its fabrication method are disclosed. The flexible variable capacitor comprises two highly conductive flexible electrode layers and an elastomeric dielectric insulating layer located between the two highly conductive flexible electrode layers. The highly conductive flexible electrode layers contain a first polymer elastomer and carbon nanomaterials, and the elastomeric dielectric insulating layer contains a second polymer elastomer and functional ceramic nanoparticles. The fabrication method of the flexible variable capacitor is as follows: first, an elastomeric composite film with different functions is prepared; then, the upper and lower electrode layers are pressed together with the intermediate elastomeric insulating layer to obtain a stretchable strip-shaped planar capacitor. Unlike existing technologies, this application uses independently developed highly conductive flexible electrodes to replace traditional silver-oil electrodes, significantly reducing the cost of the variable capacitor device and improving its integration and operability. The fabricated flexible variable capacitor features high dielectric constant, low dielectric loss, simple fabrication process, and sensitivity to deformation.

Description

Technical Field

[0001] This application belongs to the field of electronic components, and specifically relates to a flexible variable capacitor and its preparation method. Background Technology

[0002] With the rapid development of electronic information technology, the pace of digital electronic product upgrades is accelerating. The production and sales of consumer electronics, primarily flat-screen TVs, laptops, and digital cameras, continue to grow, driving the growth of the capacitor industry. Among these, novel mechanical energy harvesting technology, with variable capacitors as its core component, is considered one of the most promising power generation technologies due to its green and environmentally friendly advantages. Developing highly efficient electroactive materials is crucial for the development of mechanical energy harvesting technology. Variable capacitors based on dielectric elastomers require no human intervention during their service life, have an extremely long lifespan, and can continuously provide power to various autonomous microelectronic devices. Currently, most high-performance, high-quality flexible variable capacitors are based on pure dielectric elastomers and use silver oil and carbon black dispersions as flexible electrodes, resulting in poor operability and difficulties in large-scale production. Therefore, there remains a demand for flexible variable capacitors with controllable quality and performance that can be mass-produced. Summary of the Invention

[0003] To address the aforementioned shortcomings, this application provides a flexible variable capacitor comprising two highly conductive flexible electrode layers and an elastomeric dielectric insulating layer located between the two highly conductive flexible electrode layers. The highly conductive flexible electrode layers comprise a first polymer elastomer and carbon nanomaterials, and the elastomeric dielectric insulating layer comprises a second polymer elastomer and functional ceramic nanoparticles.

[0004] In one embodiment, the first polymer elastomer and the second polymer elastomer are each independently selected from at least one of thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and polyester ether thermoplastic elastomer (TPEE); the carbon nanomaterial is selected from at least one of carbon nanotubes with an aspect ratio of 1000, carbon black with a diameter of 100 nm, graphene, and carbon nanofibers; the functional ceramic nanoparticles are selected from at least one of barium titanate, magnesium titanate, titanium dioxide, zinc oxide, and lead zirconate titanate with a diameter of 100 nm.

[0005] In one embodiment, in the highly conductive flexible electrode layer, the first polymeric elastomer has a mass fraction of 85%-90%, and the carbon nanomaterial has a mass fraction of 10%-15%. In the elastomer dielectric insulating layer, the second polymeric elastomer has a mass fraction of 30%-90%, and the functional ceramic nanoparticles have a mass fraction of 10%-70%.

[0006] In a preferred embodiment, the mass fraction of the second polymer elastomer in the elastomer dielectric insulating layer is 50%-70%, and the mass fraction of the functional ceramic nanoparticles is 30%-50%.

[0007] This application also provides a method for fabricating a flexible variable capacitor, comprising:

[0008] 1) Prepare a highly conductive flexible electrode layer, wherein the highly conductive flexible electrode layer comprises a first polymer elastomer and carbon nanomaterials;

[0009] 2) Prepare an elastomer dielectric insulating layer, wherein the elastomer dielectric insulating layer comprises a second polymer elastomer and functional ceramic nanomaterials;

[0010] 3) Two highly conductive flexible electrode layers are respectively attached to the two sides of the elastomer dielectric insulating layer;

[0011] 4) The upper and lower highly conductive flexible electrode layers are laminated together with the middle elastomer dielectric insulating layer using a lamination process.

[0012] Preferably, in step 1), the step of preparing the highly conductive flexible electrode layer includes:

[0013] A. The carbon nanomaterial and surfactant are added to an organic solvent at a mass ratio of 1:0.8-1:1.2 and ultrasonically dispersed for 30-40 min to obtain a carbon nanomaterial suspension. The surfactant is selected from at least one of γ-aminopropyltriethoxysilane (silane coupling agent KH-550, Kangjin New Material Technology Co., Ltd.) and γ-methacryloyloxypropyltrimethoxysilane (silane coupling agent KH-570, Kangjin New Material Technology Co., Ltd.). The organic solvent is selected from at least one of N,N-dimethylformamide DMF and tetrahydrofuran THF.

[0014] B. Add the first polymer elastomer to an organic solvent and heat to dissolve it to obtain a first polymer elastomer solution, wherein the organic solvent is selected from DMF and THF;

[0015] C. The carbon nanomaterial suspension is mixed evenly with the first polymer elastomer solution to obtain a first polymer elastomer-carbon nanomaterial composite material precursor, wherein the mass ratio of the first polymer elastomer to the carbon nanomaterial is 85:15-90:10.

[0016] D. The first polymer elastomer-carbon nanomaterial composite precursor is coated into a film and dried at 75-85℃ for 10-15 hours to obtain a highly conductive flexible electrode layer film with a film thickness of 15-50μm.

[0017] Preferably, in step 2), the step of preparing the elastomer dielectric insulating layer includes:

[0018] A. The second polymer elastomer and an organic solvent are mixed at a mass ratio of 1:1.8-1:2.2, heated and stirred to obtain a solution with a certain viscosity, wherein the organic solvent is selected from DMF and THF;

[0019] B. Add the suspension of the functional ceramic nanoparticles and the organic solvent to the solution prepared above, and mix to obtain a preliminary mixture, wherein the organic solvent is selected from DMF and THF, and the mass ratio of the second polymer elastomer to the functional ceramic nanoparticles is 30:70-90:10.

[0020] C. The preliminary mixture is kneaded to obtain a precursor of the second polymer elastomer-functional ceramic nanoparticle composite material;

[0021] D. Coat the precursor of the second polymer elastomer-functional ceramic nanoparticle composite material with a film, and dry it to obtain an elastomer dielectric insulating layer film with a film thickness of 120-180μm.

[0022] In a preferred embodiment, step 4) includes controlling the temperature of the hot press plate to 120-140°C, the interplate pressure to 0.1-0.2 MPa, and the hot pressing time to 60-80 s. Following the above lamination process, each side is pressed 4-5 times until a fully fused parallel plate capacitor is obtained.

[0023] In the above technical solutions, the mixing of the carbon nanomaterial suspension and the first polymer elastomer solution can be achieved using an ultrasonic cell disruptor or ultrasonic cell breaker; the initial mixing of the functional ceramic nanoparticles and the organic solvent suspension can be achieved using a high-speed mixer, a high-speed stirrer, or a ball mill; the mixing of the second polymer elastomer and the functional ceramic nanoparticles can be carried out using a two-roll mill, a three-roll mill, or a three-roll mill; the coating method mentioned in the above solutions generally adopts a blade coating method. The above instruments and methods are not particularly limited, and other instruments and methods that can achieve the content of the application can also be used. In the above technical solutions, the temperature of the heating, stirring, and heating-dissolving operations is 50-85℃, but it is not particularly limited, as long as the desired experimental effect is achieved. Preferably, during the drying process after coating the precursor of the second polymer elastomer-functional ceramic nanoparticle composite material, it can be dried in a forced-air oven and then transferred to a vacuum oven for further drying to prevent the generation of bubbles in the dielectric insulating layer of the elastomer.

[0024] This application uses highly conductive flexible electrodes to replace traditional silver oil electrodes, which greatly reduces the cost of variable capacitor devices, enhances integration and operability, and makes large-scale industrial production possible.

[0025] The flexible variable capacitor described in this application features high dielectric constant and low dielectric loss. Compared with traditional pure polymer capacitors, this application uses a high dielectric constant elastomer composite film as the dielectric layer and adds functional ceramic nanoparticles to the dielectric elastomer, thereby improving the dielectric constant and capacitance of the capacitor while keeping the dielectric loss of the capacitor at a low value.

[0026] The flexible variable capacitor described in this application has excellent properties such as light weight, good flexibility, large capacitance change, and high cycle stability, which can meet the requirements of most commercial flexible capacitive sensors and energy harvesters for variable capacitors. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application and the prior art, the drawings used in the embodiments and the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of this application, and those skilled in the art can obtain other embodiments based on these drawings.

[0028] Figure 1 This is a schematic diagram of a variable capacitor.

[0029] Figure 2 The images shown are scanning electron microscope images of the cross-section of the flexible variable capacitor in Embodiment 3 of this application at different magnifications. The upper and lower electrodes are TPU composite materials filled with one-dimensional carbon nanotubes, and the middle layer is TPU composite material filled with barium titanate nanoparticles.

[0030] Figure 3 The curves show the change in dielectric constant of the flexible variable capacitors obtained in Examples 1-8 as a function of frequency.

[0031] Figure 4 The curves show the AC conductivity of the flexible variable capacitors obtained in Examples 1-8 as a function of frequency.

[0032] Figure 5 The curves show the dielectric loss of the flexible variable capacitors obtained in Examples 1-8 as a function of frequency.

[0033] Figure 6 The results of dynamic dielectric tests on the flexible variable capacitors obtained in Examples 1-8 are shown. The electrode dimensions of the capacitor are 50 mm × 10 mm, and the thickness of the intermediate dielectric layer is 150 μm. The curves show the change in capacitance as a function of tensile strain during the stretching process.

[0034] Figure 7The results show the dynamic dielectric test results of the flexible variable capacitors obtained in Examples 1-8. The maximum strain during cyclic tensile-relaxation is 10%, and the changes in capacitance and strain over time are shown during the loading-unloading process. The capacitor electrode dimensions are 50mm × 10mm, and the thickness of the intermediate dielectric layer is 150μm.

[0035] Explanation of reference numerals in the attached figures

[0036] 1 Highly conductive flexible electrode layer

[0037] 2. Elastomer dielectric insulating layer

[0038] 3 Highly conductive flexible electrode layer Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] Example 1

[0041] The specific steps for preparing the highly conductive flexible electrode layer thin film are as follows:

[0042] 0.25 g of carbon nanotubes and 0.25 g of γ-aminopropyltriethoxysilane (KH550, Kangjin New Materials Technology Co., Ltd.) were added to 49 mL of DMF solvent and ultrasonically dispersed for 30 min to obtain a carbon nanotube suspension.

[0043] Add 2g of thermoplastic polyurethane (TPU) to 8mL of DMF solvent and heat to dissolve to obtain a polymer elastomer solution.

[0044] The carbon nanotube suspension was added to the polymer elastomer solution and mixed for 30 minutes using an ultrasonic cell disruptor to obtain a carbon nanotube and TPU composite precursor.

[0045] The obtained carbon nanotube-TPU composite precursor was coated onto a glass plate to form a film, which was then dried at 80°C for 12 hours to obtain a highly conductive flexible electrode layer film with a thickness of 30 μm.

[0046] The specific preparation steps of the elastomer dielectric insulating film are as follows:

[0047] 2g of TPU was mixed with 4mL of organic solvent DMF, and the mixture was heated to 85°C with stirring to obtain a TPU solution with a certain viscosity.

[0048] The TPU solution was coated onto a glass plate using a coating process. The coating was then dried at 100°C for 20 minutes in a forced-air oven and then dried at 100°C for 8 hours in a vacuum oven to remove residual solvent. The resulting elastomer dielectric insulating film was 150 μm thick.

[0049] The fabrication of a flexible variable capacitor involves the following steps:

[0050] Cut a highly conductive flexible electrode layer film and an elastomer dielectric insulating layer film. The dimensions of the highly conductive flexible electrode layer film and the elastomer dielectric insulating layer film are 50 mm in length and 10 mm in width.

[0051] Two highly conductive flexible electrode films are superimposed on an elastomer dielectric insulating film to ensure that the two electrode films do not contact each other.

[0052] A lamination process is used to press the upper and lower highly conductive flexible electrode layers together with the middle elastomer dielectric insulating layer. The lamination process includes controlling the temperature of the hot press plate at 130°C, the interplate pressure at 0.125 MPa, the hot pressing time at 60 s, and pressing each side 4-5 times until a completely fused parallel plate capacitor is obtained.

[0053] Example 2

[0054] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 90% by mass of TPU and 10% by mass of barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0055] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0056] Suspension B was obtained by mixing 0.22 g of tetragonal barium titanate nanoparticles with 1.19 mL of DMF.

[0057] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0058] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0059] A coating process was adopted, in which the obtained composite material precursor was coated on a glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 155 μm.

[0060] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0061] Example 3

[0062] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 80% by mass of TPU and 20% by mass of barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0063] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0064] Suspension B was obtained by mixing 0.5 g of tetragonal barium titanate nanoparticles with 1.83 mL of DMF.

[0065] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0066] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0067] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 148 μm.

[0068] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0069] Example 4

[0070] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 70% by mass TPU and 30% by mass barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0071] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0072] Suspension B was obtained by mixing 0.86 g of tetragonal barium titanate nanoparticles with 2.66 mL of DMF.

[0073] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0074] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0075] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 152 μm.

[0076] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0077] Example 5

[0078] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 60% by mass TPU and 40% by mass barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0079] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0080] Suspension B was obtained by mixing 1.33 g of tetragonal barium titanate nanoparticles with 3.78 mL of DMF.

[0081] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0082] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0083] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 150 μm.

[0084] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0085] Example 6

[0086] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 50% by mass TPU and 50% by mass barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0087] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0088] Suspension B was obtained by mixing 2g of tetragonal barium titanate nanoparticles with 5.33mL of DMF.

[0089] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0090] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0091] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 151 μm.

[0092] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0093] Example 7

[0094] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 40% by mass TPU and 60% by mass barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0095] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0096] Suspension B was obtained by mixing 3g of tetragonal barium titanate nanoparticles with 7.67mL of DMF.

[0097] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0098] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0099] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 150 μm.

[0100] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0101] Example 8

[0102] The highly conductive flexible electrode layer film and its preparation method are the same as in Example 1. The elastomeric dielectric insulating layer film consists of 30% by mass TPU and 70% by mass barium titanate filler. This elastomeric dielectric insulating layer film is prepared by the following steps:

[0103] 2g of TPU was mixed with 4mL of DMF, and the mixture was heated to 85℃ with stirring to obtain TPU solution A with a certain viscosity.

[0104] Suspension B was obtained by mixing 4.67 g of tetragonal barium titanate nanoparticles with 11.56 mL of DMF.

[0105] The TPU solution A and the suspension B are mixed and homogenized at 2000 rpm for 10 minutes using a high-speed mixer to obtain the initial mixture.

[0106] The initial mixture obtained above was further mixed on a three-roll mill for 10 min, with the roller spacing controlled at 5 μm and the roller speed at 108 rpm, to obtain the composite material precursor.

[0107] A coating process was adopted, in which the obtained composite material precursor was coated on a clean glass plate by a doctor blade, and then dried at 100°C for 20 min in a forced-air oven, and then dried at 100°C for 8 h in a vacuum oven to remove residual solvent, finally obtaining an elastomer dielectric insulating layer film with a thickness of 154 μm.

[0108] The fabrication method of the flexible variable capacitor is the same as in Example 1.

[0109] The dielectric properties of the flexible capacitors prepared in the above embodiments were characterized, such as... Figure 3 As shown, the dielectric constant of the capacitor increases significantly with increasing barium titanate content. At 1000 Hz, as the barium titanate content increases from 0 to 70%, the dielectric constant of the capacitor increases from 6.7 to 19.7. Figure 4 , Figure 5 It can be seen that its conductivity and dielectric loss remain at relatively low values. For example... Figure 6As shown, the capacitance of the flexible capacitor prepared in this application is sensitive to material deformation. When the tensile strain reaches 17%, the capacitance change of the capacitor in Example 8 at 1000Hz reaches 78pF. Under the same test conditions, the capacitance change of a conventional pure polymer capacitor of the same size is only 29pF. Through cyclic tensile testing, the capacitance change of the capacitor is significantly higher than that of the capacitor in Example 8. Figure 7 It can be observed that when the cyclic strain is 10%, the higher the ceramic particle content, the greater the capacitance change. The capacitor with a 50% filler content exhibits excellent overall performance, including light weight, good flexibility, large capacitance change, and high cyclic stability.

[0110] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A flexible variable capacitor, comprising two highly conductive flexible electrode layers and an elastomeric dielectric insulating layer located between the two highly conductive flexible electrode layers, wherein, The highly conductive flexible electrode layer comprises a first polymer elastomer and carbon nanomaterials, and the elastomer dielectric insulating layer comprises a second polymer elastomer and functional ceramic nanoparticles. The first polymer elastomer and the second polymer elastomer are each independently selected from at least one of thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and polyester ether thermoplastic elastomer (TPEE); the carbon nanomaterial is selected from at least one of carbon nanotubes with an aspect ratio of 1000, carbon black with a diameter of 100 nm, graphene, and carbon nanofibers; the functional ceramic nanoparticles are selected from at least one of barium titanate, magnesium titanate, titanium dioxide, zinc oxide, and lead zirconate titanate with a diameter of 100 nm. In the highly conductive flexible electrode layer, the mass fraction of the first polymer elastomer is 85%-90%, and the mass fraction of the carbon nanomaterial is 10%-15%. In the elastomer dielectric insulating layer, the mass fraction of the second polymer elastomer is 30%-70%, and the mass fraction of the functional ceramic nanoparticles is 30%-70%.

2. The flexible variable capacitor according to claim 1, wherein, The second polymer elastomer in the elastomer dielectric insulating layer has a mass fraction of 50%-70%, and the functional ceramic nanoparticles have a mass fraction of 30%-50%.

3. The flexible variable capacitor according to claim 1, wherein, The dielectric constant of the elastomer dielectric insulating layer is 7.5-19.

7.

4. The flexible variable capacitor according to claim 1, wherein, The dielectric loss of the elastomeric dielectric insulating layer is 0.02-0.

06.

5. The flexible variable capacitor according to claim 1, wherein, The maximum capacitance change rate of the flexible variable capacitor is 67%.

6. The flexible variable capacitor according to claim 1, wherein, The maximum tensile strain of the flexible variable capacitor is 75%.

7. A method for preparing a flexible variable capacitor according to any one of claims 1-6, comprising: 1) Prepare a highly conductive flexible electrode layer, wherein the highly conductive flexible electrode layer comprises a first polymer elastomer and carbon nanomaterials, and the mass ratio of the first polymer elastomer to the carbon nanomaterials is 85:15-90:10; 2) Prepare an elastomer dielectric insulating layer, wherein the elastomer dielectric insulating layer comprises a second polymer elastomer and functional ceramic nanoparticles, and the mass ratio of the second polymer elastomer to the functional ceramic nanoparticles is 30:70-70:30; 3) Two highly conductive flexible electrode layers are respectively attached to the two sides of the elastomer dielectric insulating layer; 4) The upper and lower highly conductive flexible electrode layers are laminated together with the middle elastomer dielectric insulating layer using a lamination process.

8. The method for fabricating a flexible variable capacitor according to claim 7, wherein, The step of preparing the highly conductive flexible electrode layer includes: A. The carbon nanomaterial and surfactant are added to an organic solvent at a mass ratio of 1:0.8-1:1.2 and ultrasonically dispersed for 30-40 min to obtain a carbon nanomaterial suspension. The surfactant is selected from at least one of γ-aminopropyltriethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, and the organic solvent is selected from at least one of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). B. Add the first polymer elastomer to an organic solvent and heat to dissolve it to obtain a first polymer elastomer solution, wherein the organic solvent is selected from DMF and THF; C. Mix the carbon nanomaterial suspension with the first polymer elastomer solution evenly to obtain a first polymer elastomer-carbon nanomaterial composite material precursor; D. The first polymer elastomer-carbon nanomaterial composite precursor is coated into a film and dried at 75-85℃ for 10-15 hours to obtain a highly conductive flexible electrode layer film with a film thickness of 15-50μm.

9. The method for fabricating a flexible variable capacitor according to claim 7, wherein, The step of preparing the elastomer dielectric insulating layer includes: A. The second polymer elastomer and an organic solvent are mixed at a mass ratio of 1:1.8-1:2.

2. The mixture is heated and stirred to obtain a solution with a certain viscosity. The organic solvent is selected from DMF and THF. B. Add the suspension of the functional ceramic nanoparticles and organic solvent to the solution prepared above, mix well to obtain a preliminary mixture, wherein the organic solvent is selected from DMF and THF; C. The preliminary mixture is kneaded to obtain a precursor of the second polymer elastomer-functional ceramic nanoparticle composite material; D. Coat the precursor of the second polymer elastomer-functional ceramic nanoparticle composite material with a film, and dry it to obtain an elastomer dielectric insulating layer film with a film thickness of 120-180μm.

10. The method for fabricating a flexible variable capacitor according to claim 7, wherein, Step 4) includes controlling the temperature of the hot press plate to 120-140℃, the interplate pressure to 0.1-0.2MPa, and the hot pressing time to 60-80s. Following the above lamination process, each side is pressed 4-5 times until a fully fused parallel plate capacitor is obtained.

Images