Flexible and high-strength composite piezoelectric fiber film as well as preparation method and application thereof

Abstract

The invention relates to a flexible and high-strength composite piezoelectric fiber film as well as a preparation method and application thereof, and the preparation method comprises the following steps: dissolving PVDF (Polyvinylidene Fluoride) or a copolymer thereof in a solvent to obtain a first solution; dissolving a strong dipole moment asymmetric polar inorganic metal salt in a solvent to obtain a second solution; uniformly mixing the first solution and the second solution, adding the multifunctional bio-based polymer, performing ultrasonic stirring until a uniform composite spinning solution is formed, and performing electrostatic spinning to obtain the composite piezoelectric fiber film. The fiber film provided by the invention integrates the mechanical strength and chemical stability of PVDF and copolymer thereof and the flexibility and water absorption of bio-based polymer. Meanwhile, inorganic metal salt is introduced to play a role of a beta-phase nucleating agent in the electrostatic spinning PVDF crystallization process, the piezoelectric output performance of the electrostatic spinning PVDF nano piezoelectric composite film is enhanced, and the mechanical performance of the fiber film is improved through the metal coordination effect of metal ions and hydroxyl or carboxyl on the bio-based polymer; the application potential in the fields of sensors, battery diaphragms, antibacterial coatings and the like is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber film preparation, and in particular to a flexible, high-strength composite piezoelectric fiber film and a preparation method and application thereof. Background Art

[0002] Fiber film refers to a material made of fiber material and has film properties, usually with a certain degree of flexibility and strength. This type of film can be made of natural fibers (such as cellulose, chitosan, etc.) or synthetic fibers (such as polyester, polyurethane, etc.). Fiber films have a wide range of applications in many fields, such as packaging, environmental protection, biomedicine, and electronic products. The most commonly used matrix material is PVDF, which has excellent chemical resistance and can resist corrosion from a variety of chemicals, including acids, alkalis, and organic solvents. This allows PVDF films to be used in situations involving corrosive environments, such as chemical plants, laboratories, and other industrial applications. It also has good electrical insulation properties and is suitable for electronic and electrical applications, such as cable insulation, sensors, and battery separator materials.

[0003] However, most fiber films are PVDF mixed with other reinforcing materials, which makes the composite fiber film have better mechanical and piezoelectric properties.

[0004] The Chinese patent with application number CN202211211515.7 discloses a PVDF piezoelectric film and a preparation method thereof. The invention dissolves PVDF in an organic solvent to obtain a PVDF solution, and the PVDF solution is coated on a glass substrate, dried, and then cooled to form a PVDF diaphragm. The diaphragm is uniaxially stretched and polarized to generate a polarized PVDF film. The PVDF piezoelectric film is obtained by vacuum spin coating of a PEDOT:PSS aqueous solution and finally drying at 70-100°C. Although the piezoelectric film obtained by this method improves the piezoelectric properties of the PVDF piezoelectric film, the process of improving its piezoelectric properties is more complicated, and the overall mechanical stability of the film cannot be guaranteed.

[0005] The Chinese patent application number 201911177706.4 discloses a composite piezoelectric film and its preparation method. The invention uses pure natural plant nanocellulose fibers, Mxene and polyvinylidene fluoride as raw materials, and prepares nanocellulose / PVDF composite films with strong piezoelectric properties through mechanical mixing, drying film formation and high-voltage polarization. This method requires mechanical mixing, high-voltage polarization and other processes to prepare composite films with strong piezoelectric properties. The process is cumbersome and not conducive to large-scale production and application.

[0006] Based on this, it is necessary to provide a method for preparing a flexible composite fiber film material with a dual interpenetrating network structure that has excellent mechanical properties and piezoelectric properties with simple operation and low cost to solve the above technical problems. Summary of the invention

[0007] In order to overcome the defects of the prior art that the process of preparing PVDF-based piezoelectric films is complicated and it is difficult to improve both the mechanical properties and the piezoelectric properties at the same time, the present invention provides a flexible, high-strength composite piezoelectric fiber film and its preparation method and application. The present invention uses electrospinning combined with in-situ construction technology, multifunctional bio-based polymers, strong dipole moment asymmetric polar inorganic metal salts as reinforcing phases, and PVDF or its copolymer as a matrix phase to prepare a flexible, high-strength composite piezoelectric fiber film. The multifunctional bio-based polymer used in the present invention has good adhesion properties. Adding the multifunctional bio-based polymer to the mixed solution can improve the tensile strength and tear resistance of the film, making it more durable during use. Strong dipole moment asymmetric polar inorganic metal salts can not only be used as conductive fillers, but also improve the mechanical properties and thermal stability of composite materials.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] One of the purposes of the present invention is to provide a method for preparing a flexible, high-strength composite piezoelectric fiber film, comprising the following steps:

[0010] S1, dissolving PVDF or its copolymer in a solvent to obtain a first solution; dissolving a strong dipole moment asymmetric polar inorganic metal salt in a solvent to obtain a second solution;

[0011] S2, mixing the first solution and the second solution evenly, adding the multifunctional bio-based polymer, ultrasonicating and continuing to stir until a uniform composite spinning solution is formed;

[0012] S3. Electrospinning the composite spinning solution to obtain a flexible, high-strength composite piezoelectric fiber film.

[0013] Further, in S1, the solvent is one of the following solvent combinations:

[0014] ① A mixed solvent prepared from tetrahydrofuran and N,N-dimethylformamide, the mass ratio of the two being (2-8):(8-2);

[0015] ② A mixed solvent prepared from toluene and tetrahydrofuran, the mass ratio of the two being (2-8):(8-2);

[0016] ③ A mixed solvent prepared from N,N-dimethylformamide and dichloromethane, the mass ratio of the two being (2-8):(8-2);

[0017] ④ A mixed solvent prepared from N,N-dimethylformamide and acetone, the mass ratio of the two being (2-8):(8-2).

[0018] Furthermore, in S1, the PVDF or its copolymer satisfies at least one of the following conditions:

[0019] ① The molecular weight of the PVDF or its copolymer is 200,000 to 1,000,000;

[0020] ② The PVDF or its copolymer is selected from any one of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-fluorinated polymer (PVDF-HFP), polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) or polyvinylidene fluoride-chlorovinyl fluoride (PVDF-CTFE);

[0021] ③ The mass concentration of the PVDF or its copolymer is 70% to 90%;

[0022] ④ The PVDF or its copolymer is dissolved in the solvent by adding PVDF or its copolymer into the solvent and stirring for 1 to 6 hours in a constant temperature water bath at 60°C.

[0023] Further, in S1, the strong dipole moment asymmetric polar inorganic metal salt satisfies at least one of the following conditions:

[0024] ① The strong dipole moment asymmetric polar inorganic metal salt includes one or more of CuCl2·2H2O, FeCl2·4H2O, CoCl2·6H2O, NiCl2·6H2O, SnCl2·2H2O and FeCl3·6H2O.

[0025] ② The mass concentration of the inorganic salt in the strong dipole moment asymmetric polar inorganic metal salt solution is 0.5% to 5%.

[0026] Further, in S2, the multifunctional bio-based polymer satisfies at least one of the following conditions:

[0027] ① The multifunctional bio-based polymer includes one or more of cellulose nanocrystals, cellulose nanofibers, methyl cellulose, carboxymethyl cellulose, sodium alginate, gelatin and chitosan.

[0028] ② The mass ratio of the multifunctional bio-based polymer to the PVDF or its copolymer is (0.02-0.1):1.

[0029] Furthermore, in S2, the power of the ultrasound is 50W-100W, the frequency is 20kHz-1MHz, and the processing time is 1h-3h; the stirring time is 9h-12h.

[0030] Further, in S3, the electrospinning is specifically: injecting the composite spinning solution into a syringe and placing it in an electrospinning device to adjust the spinning parameters for stable spinning, collecting the fiber film after spinning, and drying it to obtain a flexible, high-strength composite piezoelectric fiber film, and the specification of the syringe can be 10mL, 20mL or 50mL;

[0031] The spinning parameters are as follows: receiving distance 8-15 cm, drum speed 150-800 r / min, liquid inlet flow rate 0.5-5 ml / h, spinning voltage 8-12 kv, humidity 30-50%, and spinning time 1-3 h.

[0032] Further, the drying is specifically one of the following operations:

[0033] ① Place the prepared fiber film in a dry environment with a humidity of 30-40% to remove excess moisture;

[0034] ② Place the prepared fiber film in a low-temperature oven at 40-50°C to dry to remove excess moisture.

[0035] The second object of the present invention is to provide a flexible, high-strength composite piezoelectric fiber film, which is prepared by the preparation method as described above, and the composite fiber film has a double interpenetrating network structure inside.

[0036] The third object of the present invention is to use the flexible, high-strength composite piezoelectric fiber film as described above in the preparation of sensors, battery separators, antibacterial coatings, etc.

[0037] Mechanism of action:

[0038] The present invention enhances the mechanical stability and ductility of the composite piezoelectric fiber film by physical entanglement and hydrogen bonding between PVDF or its copolymer and bio-based polymers rich in hydroxyl or carboxyl functional groups. The strong dipole moment asymmetric polar inorganic metal salt is arranged in an electric dipole orientation, which can play the role of a β-phase nucleating agent in the crystallization process of electrostatic spinning PVDF or its copolymer, greatly enhancing the piezoelectric output of the composite piezoelectric fiber film. In addition, the metal ions of the inorganic metal salt react with the bio-based polymers rich in hydroxyl or carboxyl functional groups to form a chemical cross-linked network, and are closely combined with the PVDF or its copolymer network through hydrogen bonding, ion-dipole and other interactions, and finally form a double interpenetrating network flexible, high-strength composite piezoelectric fiber film. When the composite fiber film is subjected to external force, the synergistic effect of the double interpenetrating network can effectively disperse the stress, thereby improving the overall performance of the composite piezoelectric fiber film. Finally, a flexible, high-strength composite piezoelectric fiber film was produced by combining electrospinning with an in-situ construction method. Compared with traditional piezoelectric film forming methods such as the "coating method", it can simultaneously stretch and electric field polarize polymer jets with a wide range of raw materials to simply and efficiently obtain a composite piezoelectric fiber film with both excellent mechanical properties and piezoelectric properties, which has great application prospects.

[0039] Compared with the prior art, the present invention uses a mixed solvent. Compared with a single solvent that has limited solubility for different substances, a mixed solvent can integrate the solubility characteristics of multiple solvents, making PVDF or its copolymer and asymmetric inorganic metal salts with strong dipole moment easier to dissolve, preventing the inorganic salt from reacting with PVDF or multifunctional bio-based polymers to cause gelation, thereby maintaining the uniformity of the dispersion of the raw materials in the solution for a longer time, which is beneficial to the subsequent electrostatic spinning operation. At the same time, by changing the composition ratio of the mixed solvent, the polarity, boiling point, volatilization rate and other parameters of the solvent system can be flexibly adjusted to adjust the rheological properties of the solution, thereby affecting the crystallization behavior, phase separation degree and intermolecular interaction of the composite spinning solution flow of PVDF or its copolymer in the film forming process, and finally achieving precise regulation of the piezoelectric properties, mechanical properties, thermal stability and other aspects of the composite piezoelectric fiber membrane material. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart for the overall preparation of the present invention;

[0041] Figure 2 This is a scanning electron microscope photograph of the flexible, high-strength composite piezoelectric fiber film prepared in Example 1. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. If no specific conditions are specified, the conventional conditions or the conditions recommended by the manufacturer shall be followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0044] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0045] Embodiment 1:

[0046] This embodiment provides a method for preparing a flexible, high-strength composite piezoelectric fiber film having a double interpenetrating network structure, and the steps are as follows:

[0047] (1) N,N-dimethylformamide (DMF) and acetone were mixed in a mass ratio of 2:5 to obtain a mixed solvent, and then PVDF was gradually added to the mixed solvent. The mixture was stirred at 500 rpm for 1 h in a constant temperature water bath at 60 degrees Celsius using an electromagnetic stirrer until the PVDF was completely dissolved, thereby obtaining a uniform PVDF solution with a mass concentration of 88%. FeCl3·6H2O was added to the mixed solvent to obtain an inorganic salt solution with a mass concentration of 3%, which was then added to the dissolved PVDF solution and stirred again to ensure uniformity. Finally, the weighed carboxymethyl cellulose was added, ultrasonically treated for 1 h, and then stirred for 12 h to obtain a composite spinning solution. The mass concentration of carboxymethyl cellulose in the spinning solution was 3%.

[0048] (2) Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. The spinning parameters are: receiving distance 15 cm, drum speed 500 r / min, liquid inlet flow rate 1 ml / h, spinning voltage 12 kV, humidity 31%, spinning time 1 h, and obtain a composite fiber film.

[0049] (3) The composite fiber film obtained in step (2) is further dried in a low-temperature oven at 40 degrees Celsius to remove excess moisture to obtain a flexible composite piezoelectric fiber film having a double interpenetrating network structure.

[0050] The scanning electron microscope image of the prepared flexible composite piezoelectric fiber film with a double interpenetrating network structure is shown in Figure 2As shown in the figure, it can be seen that the diameter of the composite nanofibers is uniform and no beaded structure is generated, indicating that the prepared composite spinning solution has good spinnability, and no obvious beads or surface defects are observed in the fibers, indicating that FeCl3·6H2O and carboxymethyl cellulose are evenly distributed on the fiber surface, giving it excellent mechanical stability and piezoelectricity.

[0051] Embodiment 2:

[0052] This embodiment provides a method for preparing a flexible composite piezoelectric fiber film having a double interpenetrating double network structure, and the steps are as follows:

[0053] (1) Tetrahydrofuran and N,N-dimethylformamide (DMF) were mixed in a mass ratio of 2:5 to obtain a mixed solvent, and then PVDF-HFP was gradually added to the mixed solvent, and an electromagnetic stirrer was used to stir at 500 rpm for 1 hour under a constant temperature water bath of 60 degrees Celsius until PVDF-HFP was completely dissolved, thereby obtaining a uniform PVDF-HFP solution with a mass concentration of 75%. FeCl3·6H2O was added to the mixed solvent to obtain an inorganic salt solution with a mass concentration of 3%, and then added to the dissolved PVDF-HFP solution, and stirred again to ensure uniformity. Finally, the weighed sodium alginate was added, and after ultrasonic treatment for 1 hour, it was stirred for 12 hours to obtain a composite spinning solution, and the mass concentration of sodium alginate in the spinning solution was 3%.

[0054] (2) Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. The spinning parameters are: receiving distance 15 cm, drum speed 800 r / min, liquid inlet flow rate 1 ml / h, spinning voltage 12 kV, humidity 31%, spinning time 1 h, and obtain a composite fiber film.

[0055] (3) The fiber film obtained in step (2) is further dried in a low-temperature oven at 40 degrees Celsius to remove excess moisture to obtain a flexible composite piezoelectric fiber film with a double interpenetrating network structure.

[0056] After testing the prepared double interpenetrating network structure of the flexible composite piezoelectric fiber film, it was found that it had a breaking elongation of 170.7% under the mechanical properties test, while the breaking elongation of the pure PVDF fiber film under the same conditions was 112.8%. Analysis shows that the presence of FeCl3·6H2O and sodium alginate significantly improves the mechanical properties of the polymer, thereby improving the mechanical strength of the composite piezoelectric fiber film.

[0057] Embodiment 3:

[0058] This embodiment provides a method for preparing a flexible fiber film with a double network structure, and the steps are as follows:

[0059] (1) N,N-dimethylformamide (DMF) and acetone were mixed in a ratio of 2:5 to obtain a mixed solvent, and then PVDF-CTFE was gradually added to the mixed solvent, and stirred at 500 rpm for 1 hour in a constant temperature water bath at 60 degrees Celsius using an electromagnetic stirrer until the PVDF-CTFE was completely dissolved, thereby obtaining a uniform PVDF-CTFE solution with a mass concentration of 90%. CuCl2·2H2O was added to the mixed solvent to obtain an inorganic salt solution with a mass concentration of 4%, which was then added to the dissolved PVDF-CTFE solution and stirred again to ensure uniformity. Finally, the weighed cellulose nanocrystals were added, ultrasonically treated for 1 hour, and then stirred for 12 hours to obtain a composite spinning solution, in which the mass concentration of cellulose nanocrystals in the spinning solution was 1%.

[0060] (2) Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. The spinning parameters are: receiving distance 15 cm, drum speed 600 r / min, liquid inlet flow rate 1 ml / h, spinning voltage 12 kV, humidity 31%, spinning time 1 h, and obtain a composite fiber film.

[0061] (3) The fiber film obtained in step (2) is further dried in a low-temperature oven at 40 degrees Celsius to remove excess moisture to obtain a flexible composite piezoelectric fiber film with a double interpenetrating network structure.

[0062] Flexible sensors were assembled using the flexible composite piezoelectric fiber film with the double interpenetrating network structure prepared above. Tests showed that the maximum output voltage of the sensor was 12.20V under 30% relative humidity, 5Hz, and 10N external force, which were 7.6 times that of pure PVDF nanofiber flexible sensors, and the performance of the sensor was stable.

[0063] Embodiment 4:

[0064] This embodiment provides a flexible fiber film with a double network structure and a preparation method thereof, wherein the steps are as follows:

[0065] (1) Tetrahydrofuran and N,N-dimethylformamide (DMF) were mixed in a ratio of 2:5 to obtain a mixed solvent, and then PVDF-TrFE with a concentration of 80% was gradually added to the mixed solvent, and stirred at 500 rpm for 1 hour under a constant temperature water bath of 60 degrees Celsius using an electromagnetic stirrer until the PVDF-TrFE was completely dissolved, thereby obtaining a uniform PVDF-TrFE solution with a mass concentration of 80%. CuCl2·2H2O was added to the mixed solvent to obtain an inorganic salt solution with a mass concentration of 3%, which was then added to the dissolved PVDF-TrFE solution and stirred again to ensure uniformity. Finally, the weighed gelatin was added, ultrasonically treated for 1 hour, and then stirred for 12 hours to obtain a composite spinning solution, in which the mass concentration of gelatin in the spinning solution was 1%.

[0066] (2) Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. Inject the composite spinning solution into a 20 mL syringe and place it in an electrospinning device. The spinning parameters are: receiving distance 15 cm, drum speed 800 r / min, liquid inlet flow rate 1 ml / h, spinning voltage 12 kV, humidity 31%, spinning time 1 h, and obtain a composite fiber film.

[0067] (3) The composite fiber film obtained in step (2) is further dried in a low-temperature oven at 40 degrees Celsius to remove excess moisture to obtain a flexible composite piezoelectric fiber film with a double interpenetrating network structure.

[0068] It has been verified that the preparation method of the flexible composite piezoelectric fiber film with a double interpenetrating network structure of the present invention is simple in preparation method, low in cost, easy to shape the product, short in reaction time, and very suitable for large-scale production. The obtained flexible composite piezoelectric fiber film with a double interpenetrating network structure combines the mechanical strength and chemical stability of PVDF and its copolymers, as well as the flexibility and water absorption of bio-based polymers, to form a multifunctional composite material. At the same time, the introduction of inorganic metal salts can play the role of β-phase nucleating agent in the crystallization process of electrospun PVDF, greatly enhancing the piezoelectric output performance of the electrospun PVDF nanocomposite piezoelectric film, thereby broadening its application potential in the fields of sensors, battery separators, antibacterial coatings, etc.

[0069] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a flexible, high-strength composite piezoelectric fiber film, characterized in that: The steps include: S1, dissolving PVDF or its copolymer in a solvent to obtain a first solution; dissolving a strong dipole moment asymmetric polar inorganic metal salt in a solvent to obtain a second solution; S2, mixing the first solution and the second solution evenly, adding the multifunctional bio-based polymer, ultrasonicating and continuing to stir until a uniform composite spinning solution is formed; S3. Electrospinning the composite spinning solution to obtain a flexible, high-strength composite piezoelectric fiber film.

2. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S1, the solvent is one of the following solvent combinations: ① A mixed solvent prepared from tetrahydrofuran and N,N-dimethylformamide, the mass ratio of the two being (2-8):(8-2); ② A mixed solvent prepared from toluene and tetrahydrofuran, the mass ratio of the two being (2-8):(8-2); ③ A mixed solvent prepared from N,N-dimethylformamide and dichloromethane, the mass ratio of the two being (2-8):(8-2); ④ A mixed solvent prepared from N,N-dimethylformamide and acetone, the mass ratio of the two being (2-8):(8-2).

3. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S1, the PVDF or its copolymer satisfies at least one of the following conditions: ① The molecular weight of the PVDF or its copolymer is 200,000 to 1,000,000; ② The PVDF or its copolymer is selected from any one of polyvinylidene fluoride, polyvinylidene fluoride-fluorinated polymer, polyvinylidene fluoride-trifluoroethylene or polyvinylidene fluoride-chloroethylene fluoride; ③ The mass concentration of the PVDF or its copolymer is 70% to 90%; ④ The PVDF or its copolymer is dissolved in the solvent by adding PVDF or its copolymer into the solvent and stirring for 1 to 6 hours in a constant temperature water bath at 60°C.

4. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S1, the strong dipole moment asymmetric polar inorganic metal salt satisfies at least one of the following conditions: ① The strong dipole moment asymmetric polar inorganic metal salt includes one or more of CuCl2·2H2O, FeCl2·4H2O, CoCl2·6H2O, NiCl2·6H2O, SnCl2·2H2O and FeCl3·6H2O; ② The mass concentration of the inorganic salt in the strong dipole moment asymmetric polar inorganic metal salt solution is 0.5% to 5%.

5. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S2, the multifunctional bio-based polymer satisfies at least one of the following conditions: ① The multifunctional bio-based polymer includes one or more of cellulose nanocrystals, cellulose nanofibers, methyl cellulose, carboxymethyl cellulose, sodium alginate, gelatin and chitosan; ② The mass ratio of the multifunctional bio-based polymer to the PVDF or its copolymer is (0.02-0.1):

1.

6. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S2, the power of the ultrasound is 50W-100W, the frequency is 20kHz-1MHz, and the treatment time is 1h-3h; the stirring time is 9h-12h.

7. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 1, characterized in that: In S3, the electrospinning specifically comprises: injecting the composite spinning solution into a syringe and placing the syringe in an electrospinning device to adjust the spinning parameters for stable spinning, collecting the fiber film after spinning, and drying the fiber film to obtain a flexible, high-strength composite piezoelectric fiber film; The spinning parameters are as follows: receiving distance 8-15 cm, drum speed 150-800 r / min, liquid inlet flow rate 0.5-5 ml / h, spinning voltage 8-12 kv, humidity 30-50%, and spinning time 1-3 h.

8. The method for preparing a flexible, high-strength composite piezoelectric fiber film according to claim 7, characterized in that: The drying is specifically one of the following operations: ① Place the prepared fiber film in a dry environment with a humidity of 30-40% to remove excess moisture; ② Place the prepared fiber film in a low-temperature oven at 40-50°C to dry to remove excess moisture.

9. A flexible, high-strength composite piezoelectric fiber film, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 8, and the composite fiber film has a double interpenetrating network structure inside.

10. Use of the flexible, high-strength composite piezoelectric fiber film as claimed in claim 9 in the preparation of sensors, battery separators, and antibacterial coatings.

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