TWI831209B - Preparation method of graphene-pvdf piezoelectric material in dual solvent system - Google Patents

Abstract

A preparation method of graphene-PVDF piezoelectric material in a dual-solvent system, comprising the following steps: mixing the first solvent with the second solvent to obtain a dual solvent mixture; the dual solvent mixture is distributed into the first part of the dual solvent and the second part of the dual solvent; the PVDF polymer is added to the first part of the dual solvent for dissolving to obtain a mother liquor; the graphene powder is added to the second part of the dual solvent and mixed to obtain the graphene dispersion; the graphene dispersion is added to the mother liquor and mixed to obtain a graphene-PVDF polymer paste; and removing the first solvent and the second solvent in the graphene-PVDF polymer paste to obtain a graphene-PVDF piezoelectric material with good conductivity.

Description

Dual solvent system made of graphene-polyvinylidene fluoride piezoelectric material Preparation method

The present invention relates to a method for preparing a piezoelectric material, in particular to a method for preparing a graphene-polyvinylidene fluoride piezoelectric material using a dual-solvent system that can obtain good piezoelectric properties without consuming a large amount of energy during the preparation process. .

Since the piezoelectric effect was discovered on quartz crystals, piezoelectric materials have begun to attract widespread attention. With in-depth research, a large number of piezoelectric materials have been discovered, such as ceramic materials, polymer piezoelectric films, piezoelectric composite materials, etc. . These materials have a very wide range of uses and play an important role in functional conversion devices such as electricity, magnetism, sound, light, heat, moisture, gas, and force.

Piezoelectric material is a material that can convert mechanical energy and electrical energy. Its mode of action is mainly through the material itself bending, stretching, or applying other mechanical forces to produce electrical energy, and vice versa, that is, If electrical energy is supplied to a material, the material will deform accordingly. At present, research on piezoelectric materials is mainly focused on their application in energy harvesting, artificial muscles and sensors. Of course, piezoelectric materials can also be used in daily equipment, such as in speakers. It relies on piezoelectric sheets to convert electrical signals and then into mechanical vibrations, thereby causing sound waves to generate predetermined audio signals.

Generally speaking, piezoelectric materials are dielectrics that are polarized under pressure and produce a potential difference between the two end surfaces. When stress is applied in a specific direction of a heteropolar crystal material, positive and negative bound charges appear on some corresponding surfaces of the crystal. The charge density is proportional to the magnitude of the applied stress. When the stress is reversed, the charges change accordingly (from positive to negative). Negative, negative becomes positive), this effect in which mechanical stress polarizes the dielectric and forms a charge on the crystal surface is called the piezoelectric effect.

Common piezoelectric materials can be divided into natural materials and artificial materials. Some natural piezoelectric materials include Berlin iron ore, sucrose, quartz, Rochelle salt, topaz, tourmaline, etc., while examples of artificial piezoelectric materials include titanium. Barium acid and lead zirconate titanate. In recent years, due to international concerns about the toxicity of lead-containing equipment, the development of lead-free piezoelectric materials has been gradually promoted to produce new and more environmentally friendly piezoelectric materials.

Among lead-free piezoelectric materials, polyvinylidene fluoride polymer (PVDF) is composed of -(CH2CF2) _n -. It has the advantages of low friction coefficient, chemical resistance, and good flexibility. It is often It is used in the food processing industry, petrochemical industry, and electronic and electrical industries. In addition, polyvinylidene fluoride has excellent electrical properties, high insulation, high dielectric strength and other properties, so it is widely used as a piezoelectric material. .

According to the analysis of the characteristics of polyvinylidene fluoride, it can be seen that since polyvinylidene fluoride is a long-chain molecule bonded by CFCH, it is a semi-crystalline polymer in its normal state. There are four common crystal forms: α , β, γ and δ (also including a less formed ε type), they are formed under different conditions, and can be transformed into each other under certain conditions (the action of heat, electric field, mechanical and radiant energy). Here Among the four (or five) crystal forms, β and δ are both polar crystal structures. However, considering the actual operating conditions and the stability of the crystal form, polybiased diodes are used for piezoelectric applications. For vinyl fluoride, it is mainly polyvinylidene fluoride containing β crystal form. The β crystal form generally exists in stretch-oriented polyvinylidene fluoride. The molecular chains are regularly arranged, with large spontaneous polarization and orientation. The final dielectric constant increases from 6 to 8 to 11 to 14, so generally the β crystal form of polyvinylidene fluoride can be obtained by mechanically stretching the α crystal form of polyvinylidene fluoride to produce a crystal form transformation.

In a conventional technology, graphene oxide and aluminum oxide are added to polyvinylidene fluoride, and a polyvinylidene fluoride membrane is prepared using polymethyl methacrylate as a base. However, the alumina in the conventional technology , graphene oxide plus aluminum oxide all use metal cations to interact with fluorine in polyvinylidene fluoride to induce polyvinylidene fluoride to form a polarized structure, that is, to induce the α-type crystal in polyvinylidene fluoride to become β β-type crystal structure, this preparation method cannot quickly shape the β-type crystal in polyvinylidene fluoride, takes a long time, and has poor preparation efficiency.

In another conventional technology, a fiber structure is used as a base, and graphene and polyvinylidene fluoride are added to prepare a material that enhances current output. However, under this preparation method, if β-type crystals are to be formed and finalized, It requires the use of a high-voltage polarization field, which requires a large amount of energy.

Therefore, the purpose of the present invention is to provide a graphene-polymer dual-solvent system that is time-saving, energy-saving and can effectively induce more beta-type crystal structures in polyvinylidene fluoride to obtain better piezoelectric properties. Preparation method of vinylidene fluoride piezoelectric material.

Therefore, the preparation method of the graphene-polyvinylidene fluoride piezoelectric material of the dual solvent system of the present invention includes the following steps: mixing a first solvent and a second solvent to obtain a dual solvent mixture; The mixed solution is divided into a first part of dual solvent accounting for 75% to 85%, and a second part of dual solvent accounting for 15% to 25%; add polyvinylidene fluoride polymer to the first part Dissolve in a dual solvent to obtain a mother liquid; add graphene powder to the second dual solvent and mix to obtain a graphene dispersion; add the graphene dispersion to the mother liquid and mix to Obtain a graphene-polyvinylidene fluoride polymer slurry; and remove the first solvent and the second solvent in the graphene-polyvinylidene fluoride polymer slurry that has been mixed to obtain A graphene-polyvinylidene fluoride piezoelectric material.

Another object of the present invention is to provide another method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system.

Therefore, the preparation method of the graphene-polyvinylidene fluoride piezoelectric material of the dual solvent system of the present invention includes the following steps: mixing a first solvent and a second solvent to obtain a dual solvent mixture; The mixed solution is divided into a first part of dual solvent, a second part of dual solvent, and a third part of dual solvent; polyvinylidene fluoride polymer is added to the first part of dual solvent to dissolve to obtain a Mother liquor; add graphene powder to the second part of the dual solvent and mix to obtain a graphene dispersion; add the graphene dispersion to the mother liquor and mix, then use the third part of the dual solvent to lubricate the liquid. Wash a container originally loaded with the graphene dispersion to obtain a rinsing liquid; add the rinsing liquid to the mother liquor that has been mixed with the graphene dispersion and mix to obtain a graphene-polyylidene fluoride Ethylene polymer slurry; and removing the first solvent and the second solvent from the mixed graphene-polyvinylidene fluoride polymer slurry to obtain a graphene-polyvinylidene fluoride Piezoelectric materials.

The effect of the present invention is to induce more β-type crystal structures to stably form on the graphene-polyvinylidene fluoride polymer through the interaction between the respective polarities of different solvents in the dual-solvent system and the graphene-polyvinylidene fluoride polymer. Among vinylidene fluoride piezoelectric materials, the conductivity of the piezoelectric material itself is greatly improved.

S101~S106, S201~S207: steps

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which:

Figure 1 is a flow chart of the preparation method of the graphene-polyvinylidene fluoride piezoelectric material of the dual solvent system of the present invention; and

Figure 2 is a flow chart of a method for preparing a graphene-polyvinylidene fluoride piezoelectric material in another dual-solvent system according to the present invention.

The advantages and spirit of the present invention can be further understood through the following detailed description and accompanying drawings. The structure and use of the embodiment of the present invention are described in detail below. It must be understood that the present invention provides many applicable innovative concepts that can be implemented in a wide range of contexts. This particular example is merely representative of a specific manner in which to make and use the invention and does not limit the scope of the invention.

First, please refer to FIG. 1 , which is a graphene-polyvinylidene fluoride piezoelectric material preparation method of a dual-solvent system disclosed in the present invention, which at least includes the following steps S101 to S106:

Step S101, premixing the two solvents: thoroughly mixing the first solvent and the second solvent by ultrasonic vibration at room temperature for 15 minutes to 1 hour, thereby obtaining a double solvent mixture. In this embodiment, the dielectric constant of the first solvent is different from the dielectric constant of the second solvent, and the range of the dielectric constant of the first solvent is selected from 7.5 to 80. Generally speaking, the dielectric constant of the solvent The larger the constant, the more polar the solvent itself. In some embodiments, the first solvent may be one selected from tetrahydrofuran (THF), water (H ₂ O), acetone, and ethanol, and the second solvent is N-methylpyrrolidone ( NMP). In more detail, when the first solvent is tetrahydrofuran, the weight percentage of tetrahydrofuran in the double-solvent mixture is 10% to 40%. For example, when the double-solvent mixture is 50 grams, the weight of tetrahydrofuran used The weight range is between 5 grams and 20 grams, and the weight range of N-methylpyrrolidone is between 30 grams and 45 grams. When the first solvent is water, the weight percentage of water in the double-solvent mixture is 20% to 40%. When the first solvent is acetone, the weight percentage of acetone in the double-solvent mixture is 10% to 40%. When the first solvent is ethanol, the weight percentage of ethanol in the double-solvent mixture is 10% to 20%.

Step S102. Distribute the double solvent mixture into two parts. Distribute the double solvent mixture into a first part of the double solvent and a second part of the double solvent. The weight ratio of the first part of the double solvent is 0.0% of the double solvent mixture. 75% to 85% of the original weight, and the weight proportion of the second part of the double solvent is 15% to 25% of the original weight of the double solvent mixture. That is, for example, when the double solvent mixture is 50 grams , the weight range of the first dual solvent is between 37.5 grams and 42.5 grams, and the weight range of the second dual solvent is between 7.5 grams and 12.5 grams.

Step S103, the step of obtaining the mother liquid: add the polyvinylidene fluoride polymer to the first part of the dual solvent and dissolve it to obtain the mother liquid. In this embodiment, the polyvinylidene fluoride polymer may be selected from polyvinylidene fluoride, modified polyvinylidene fluoride, and combinations thereof. In some embodiments, the polyvinylidene fluoride polymer is added to the first part of the dual solvent in powder form for dissolution, and needs to be dissolved in It is carried out at a first heating temperature, and the first heating temperature is between 60°C and 85°C. It is preferable to maintain the temperature at 80°C and continue stirring until the polyvinylidene fluoride polymer powder is completely dissolved. , since unnecessary gas will be generated inside the mother liquor during the continuous stirring process, the gas removal step can also be performed on the mother liquor. This is to place the mother liquor stationary in the oven and wait for the gas to evaporate from the mother liquor at the second heating temperature. The bottom surface floats toward the top surface and escapes into the air, and the second heating temperature is between 50°C and 80°C.

Step S104, step of obtaining graphene dispersion: add graphene powder to the second portion of dual solvents and mix to obtain graphene dispersion. In this embodiment, in order to obtain a uniformly dispersed graphene dispersion, ultrasonic vibration is required for 30 minutes during mixing. The diameter of the ultrasonic probe tip is 6 mm, and the ultrasonic vibration amplitude can be as high as the oscillator can provide. 40% of maximum amplitude.

Step S105. Obtain graphene-polyvinylidene fluoride polymer slurry. Step: add the graphene dispersion liquid to the mother liquor and mix it in a homogenizer at a speed of 5600 rpm for 1 to 3 hours, thereby obtaining Graphene-polyvinylidene fluoride polymer slurry. In this embodiment, in order to prevent the first solvent and the second solvent in the graphene-polyvinylidene fluoride polymer slurry from volatilizing during the stirring and mixing process, ice may be used during mixing. The bath method is carried out at a cooling temperature, and the cooling temperature is between 5°C and 15°C. In some embodiments, the homogeneously mixed graphene-polyvinylidene fluoride polymer slurry can be further processed into As for the gas removal step in the graphene-polyvinylidene fluoride polymer slurry, it must be noted that the gas removal step included in step S105 is not to remove gas in a static and heating manner as in step S103, but It uses dynamic ultrasonic oscillation to remove gases at a cooling temperature between 5°C and 15°C. The technical method of removing gases at a cooling temperature is particularly maintained to avoid the polymerization of graphene-polyvinylidene fluoride. The first solvent and the second solvent in the material slurry volatilize and affect the formation of the β-type crystal structure, and the dynamic ultrasonic oscillation method is used to make graphene in the graphene-polyvinylidene fluoride polymer slurry. The material can have more uniform and good dispersion.

Step S106, double solvent removal step: remove the first solvent and the second solvent in the mixed graphene-polyvinylidene fluoride polymer slurry to obtain the graphene-polyvinylidene fluoride piezoelectric material, Among them, the weight ratio of graphene powder and polyvinylidene fluoride polymer is 0.1:1.

In this step S106, the graphene-polyvinylidene fluoride polymer slurry can be transferred to the surface of the substrate first, and then placed in an oven for drying at a temperature of 80°C. It is worth mentioning that due to the different solvents, The evaporation temperatures vary, so the oven temperature can be set between 70°C and 100°C depending on the solvent selected. Finally, when the graphene-polyvinylidene fluoride polymer slurry is completely dry and attached to the surface of the substrate, it can be soaked in water to separate the completely dry graphene-polyvinylidene fluoride polymer from the substrate. On the surface of the material, a graphene-polyvinylidene fluoride piezoelectric material with good piezoelectric properties is obtained.

In some embodiments, the method for transferring the graphene-polyvinylidene fluoride polymer slurry to the surface of the substrate may be selected from coating, screen printing, scraping, rubbing, adhesion, spraying, 3D Printing, molding, injection molding and combinations of the above methods.

Referring to Figure 2, the following is another method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system disclosed by the present invention, which at least includes the following steps S201 to S207:

Step S201, premixing dual solvents: The content of this step S201 is the same as that of step S101. In some embodiments, the weight ratio of the first solvent to the second solvent ranges from 1:9 to 4: 6.

Step S202: Distribute the double-solvent mixture into three parts: distribute the double-solvent mixture into the first part of the double-solvent, the second part of the double-solvent and the third part of the double-solvent. The weight proportion of the first part of the double solvent is 75% to 85% of the original weight of the double solvent mixture, the weight proportion of the second part of the double solvent is 7.5% to 12.5% of the original weight of the double solvent mixture, and the third part of the double solvent is 75% to 85% of the original weight of the double solvent mixture. The weight ratio of two parts of double solvent is 7.5% to 12.5% of the original weight of the double solvent mixture. That is, for example, when the double solvent mixture is 50 grams, the weight range of the first part of double solvent is between 37.5 grams to 42.5 grams, the weight range of the second dual solvent is between 3.75 grams and 6.25 grams, and the weight range of the third dual solvent is between 3.75 grams and 6.25 grams. In some embodiments, when the two-solvent mixture is 50 grams, the weight ratio of the first solvent to the second solvent and the third solvent is 8:1:1.

Step S203, step of obtaining mother liquor: The content of this step S203 is the same as the content of step S103.

Step S204: Obtain graphene dispersion: add graphene powder to the second part of the dual solvent in step S202 and mix to obtain a graphene dispersion. In this embodiment, in order to obtain a uniformly dispersed graphene dispersion, ultrasonic vibration can be performed for 30 minutes.

Step S205: Obtaining the rinsing solution: When adding the graphene dispersion in step S204 to the mother liquor in step S203 for mixing, the cooling temperature is maintained between 5°C and 15°C, and then, step S202 is used. The third part of the dual solvent is used to rinse the container originally loaded with the graphene dispersion to obtain a rinse solution containing graphene. This step is to prevent graphene from remaining on the wall of the container. Since the presence of graphene's π-π conjugated bonds can effectively induce the alignment of the polymer chains of polyvinylidene fluoride, a third part of the double solvent is used for rinsing. The original container containing the graphene dispersion allows the graphene remaining on the wall of the container to be collected and reused, thus preventing the graphene from not actually participating in the reaction and affecting the piezoelectric properties of the subsequent finished product.

Step S206: Obtain graphene-polyvinylidene fluoride polymer slurry. Add the rinsing liquid in step S205 to the graphene dispersion and mother liquor, mix, and perform in a homogenizer at a rotation speed of 5,600 rpm. Mix for 1 to 3 hours to obtain graphene-polyvinylidene fluoride polymer slurry. In this embodiment, the homogeneously mixed graphene-polyvinylidene fluoride polymer slurry can be further processed into The gas removal step in the graphene-polyvinylidene fluoride polymer slurry is carried out, and the gas is removed by ultrasonic vibration at a cooling temperature between 5°C and 15°C.

It should be noted that the gas removal step included in this step S205 is not to remove gas by static heating, but by dynamic ultrasonic oscillation at a cooling temperature between 5°C and 15°C. Regarding The technical means of maintaining gas removal at a cooling temperature is to avoid the volatilization of the first solvent and the second solvent in the graphene-polyvinylidene fluoride polymer slurry and affect the formation of the β-type crystal structure. The purpose of using dynamic ultrasonic oscillation is to achieve a more uniform and good dispersion of graphene in the graphene-polyvinylidene fluoride polymer slurry.

Step S207, dual solvent removal step: The content of this step S207 is the same as the content of step S106. It is worth mentioning that the step of removing the dual solvents by drying can also be carried out at room temperature, but the speed will be slower and it will take a longer time to wait for the graphene-polyvinylidene fluoride polymer slurry to completely dry and adhere. on the substrate surface.

The graphene-polyvinylidene fluoride piezoelectric material obtained by the graphene-polyvinylidene fluoride piezoelectric material preparation method of the dual-solvent system of the present invention is better than the graphene-polyvinylidene fluoride piezoelectric material using only a single solvent (for example: N-methylpyrrolidone) The piezoelectric material prepared by mixing it with graphene and polyvinylidene fluoride can effectively increase the value of the piezoelectric voltage by nearly 1 times. This is due to the different solvents in the dual-solvent system, each of which has different polarities with graphite. The interaction between graphene-polyvinylidene fluoride polymers induces more β-type crystal structures to be stably formed in graphene-polyvinylidene fluoride piezoelectric materials, so it can greatly improve piezoelectric materials. The conductivity of the material itself. In addition, the graphene-polyvinylidene fluoride piezoelectric material prepared by the graphene-polyvinylidene fluoride piezoelectric material preparation method of the dual solvent system of the present invention can make β-type crystals without additional use of high-voltage polarization fields. It is stably formed in the graphene-polyvinylidene fluoride piezoelectric material, so the invention also has the advantages of saving time and energy in manufacturing.

In summary, the graphene-polyvinylidene fluoride piezoelectric material preparation method of the dual solvent system of the present invention can indeed achieve the purpose of the present invention.

The technical content disclosed in this creation is not limited to the above-mentioned embodiments. Anything that is the same as the creative concepts and principles disclosed in this creation falls within the scope of the patent application of this creation. It should be noted that the definitions of components, such as “first” and “second” are not words of limitation, but terms of distinction. The "includes" or "includes" used in this case covers the concepts of "including" and "having" and indicates components, operating steps and/or groups or combinations of the above, and does not mean exclusion or addition. In addition, unless otherwise stated, the sequence of steps does not represent an absolute sequence. Furthermore, unless otherwise specified, reference to an element in the singular (eg, using the articles "a" or "an") does not mean "one and only one" but rather "one or more." As used in this case, "and/or" means "and" or "or", as well as "and" and "or". The range-related terms used in this case include all and/or range limitations, such as "at least", "greater than", "less than", "no more than", etc., which refer to the upper or lower limit of the range.

However, the above are only examples of the present invention, and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made based on the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of this invention.

S101~S106: Steps

Claims (20)

A method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system, which includes the following steps: mixing a first solvent and a second solvent to obtain a dual-solvent mixture, wherein the first solvent One of the two solvents is selected from tetrahydrofuran, water, acetone and ethanol; the double solvent mixture is divided into a first part of the double solvent accounting for 75% to 85%, and a second part of the double solvent accounting for 15% to 25%; add polyvinylidene fluoride polymer to the first part of the dual solvent and dissolve it to obtain a mother liquid; add graphene powder to the second part of the dual solvent and mix to obtain a mother liquid. Graphene dispersion; adding the graphene dispersion to the mother liquor and mixing to obtain a graphene-polyvinylidene fluoride polymer slurry; and removing the graphene-polyvinylidene fluoride that has been mixed. The first solvent and the second solvent in the polymer-like slurry are used to obtain a graphene-polyvinylidene fluoride piezoelectric material. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual solvent system as described in claim 1, wherein when the polyvinylidene fluoride polymer is added to the first dual solvent for dissolution, It is carried out at a first heating temperature, and the first heating temperature is between 60°C and 85°C. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual solvent system as described in claim 2, wherein the polyvinylidene fluoride polymer is added to the first dual solvent for dissolution to obtain The mother liquor step also includes a step of adding the mother liquor The gas removal step in the liquid is carried out at a second heating temperature, and the second heating temperature is between 50°C and 80°C. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 2, wherein when the graphene dispersion is added to the mother liquor for mixing, it is carried out at a cooling temperature , the cooling temperature is between 5℃ and 15℃. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 4, wherein the graphene dispersion is added to the mother liquor and mixed to obtain the graphene-polyvinylidene fluoride. The step of ethylene polymer slurry also includes a step of removing gas from the graphene-polyvinylidene fluoride polymer slurry, and the gas is removed by ultrasonic oscillation at the cooling temperature. . The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 1, wherein the weight ratio of the graphene powder to the polyvinylidene fluoride polymer is 0.1: 1. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 1, wherein the dielectric constant of the first solvent is different from the dielectric constant of the second solvent, and the first solvent The dielectric constant of the solvent ranges from 7.5 to 80. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 1, wherein the second solvent is N-methylpyrrolidone. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 8, wherein when the first solvent is tetrahydrofuran, the weight of the first solvent in the dual-solvent mixture is Percentages range from 10% to 40%. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 8, wherein when the first solvent is water, the weight of the first solvent in the dual-solvent mixture is The percentage is 20% to 40%. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 8, wherein when the first solvent is acetone, the weight of the first solvent in the dual-solvent mixture is Percentages range from 10% to 40%. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 8, wherein when the first solvent is ethanol, the weight of the first solvent in the dual-solvent mixture is The percentage is 10% to 20%. A method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual solvent system, which includes the following steps: mixing a first solvent and a second solvent to obtain a dual solvent mixture; mixing the dual solvents The liquid is divided into a first part of dual solvent, a second part of dual solvent, and a third part of dual solvent; polyvinylidene fluoride polymer is added to the first part of dual solvent to dissolve to obtain a mother liquid ; Add graphene powder to the second part of the dual solvent and mix to obtain a graphene dispersion; add the graphene dispersion to the mother solution and mix, then use the third part of the dual solvent to rinse A container originally loaded with the graphene dispersion liquid is used to obtain a rinsing liquid; the rinsing liquid is added to the mother liquid and mixed to obtain a graphene-polyvinylidene fluoride polymer slurry; and The first solvent and the second solvent in the mixed graphene-polyvinylidene fluoride polymer slurry are removed to obtain a graphene-polyvinylidene fluoride piezoelectric material. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as described in claim 13, wherein the first portion of the dual-solvent accounts for 75% to 85% of the original weight of the dual-solvent mixture. , the second part of the double solvent accounts for 7.5% to 12.5% of the original weight of the double solvent mixture, and the third part of the double solvent accounts for 7.5% to 12.5% of the original weight of the double solvent mixture. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual solvent system as described in claim 13, wherein when the polyvinylidene fluoride polymer is added to the first dual solvent for dissolution, It is carried out at a first heating temperature, and the first heating temperature is between 60°C and 85°C. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual solvent system as claimed in claim 15, wherein the polyvinylidene fluoride polymer is added to the first dual solvent for dissolution to obtain The mother liquor step also includes a step of removing gas from the mother liquor, and this step is performed at a second heating temperature, and the second heating temperature is between 50°C and 80°C. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 15, wherein when the graphene dispersion is added to the mother liquor for mixing, it is carried out at a cooling temperature , the cooling temperature is between 5℃ and 15℃. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 17, wherein the rinsing liquid is added to the mother liquor and mixed to obtain the graphene-polyvinylidene fluoride. The step of preparing polymer slurry also includes a The gas in the graphene-polyvinylidene fluoride polymer slurry is removed by ultrasonic vibration at the cooling temperature. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 13, wherein the dielectric constant of the first solvent is different from the dielectric constant of the second solvent, and the first solvent The dielectric constant range is between 7.5 and 80. The method for preparing a graphene-polyvinylidene fluoride piezoelectric material in a dual-solvent system as claimed in claim 19, wherein the weight ratio of the first solvent to the second solvent ranges from 1:9 to 4:6.

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