CN115295714A - Flexible piezoelectric nanofiber net film and preparation method and application thereof - Google Patents
Flexible piezoelectric nanofiber net film and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the field of electrostatic spinning, and particularly relates to a preparation method of a flexible piezoelectric nanofiber mesh membrane and application of the flexible piezoelectric nanofiber mesh membrane in a piezoelectric transducer. At present, most electrodes of piezoelectric energy conversion devices are two-dimensional electrodes, conductive electrodes are directly attached to the original piezoelectric materials, and the electric charges led out of the conductive electrodes are limited on the surfaces of the piezoelectric materials. Therefore, the invention utilizes the electrostatic spraying method to coat the conductive nano material on the surface of the PVDF nano fiber to form the three-dimensional electrode, utilizes the high conductivity of the conductive nano material and the high contact area between the piezoelectric nano fiber and the three-dimensional electrode to improve the piezoelectric charge transfer efficiency, and improves the electrical signal output and the piezoelectric performance under the condition of unchanged pressure and stress area.
Description
Technical Field
The invention belongs to the field of electrostatic spinning, and particularly relates to a flexible piezoelectric nanofiber net film and a preparation method and application thereof.
Background
With the aggravation of energy crisis and deterioration of natural environment, the development and utilization of clean and renewable energy have been receiving attention all over the world, and piezoelectric materials have the ability to convert mechanical strain energy into electric charges, and the principle thereof is that if pressure is applied to the piezoelectric material, charge centers of cations and anions are separated and form an electric dipole, which generates a potential difference, and if a dynamic strain phenomenon is applied to continuously change the potential, a stable pulse current flows through an external circuit. The method can be applied to the artificial skin of the robot and can also be used for various intelligent applications such as pulse detection, voice recognition and the like. Polyvinylidene fluoride (PVDF) is favored for research in the fields of electromechanical transduction, sensors, human-computer interfaces, and the like because of its high piezoelectric coefficient, flexibility, light weight, good moldability, and the like. The PVDF piezoelectric film can be prepared by applying high-voltage electric field polarization after mechanical drafting, or can be prepared by one-step molding through an electrostatic spinning method, the electrostatic spinning method does not need any post-treatment process, and is a piezoelectric polymer structure preparation technology which is simple in process, low in cost and capable of realizing large-scale production, and the prepared PVDF nanofiber film has the advantages of high piezoelectric coefficient, good biocompatibility, light weight, softness and the like, and can be used for piezoelectric transduction and sensing devices in the future.
At present, the way of improving the voltage output of the piezoelectric nanofiber is to pass through electric field polarization, such as electrostatic spinning, and is favored by virtue of simple equipment, convenient operation, low cost and capability of continuously preparing ultrafine fibers with diameters from dozens of nanometers to several micrometers, and the polarization of an electrostatic field can effectively promote the beta-phase crystal content in PVDF, thereby improving the piezoelectric performance. Without the need for additional high voltage poling and mechanical stretching, is an economically viable and relatively simple process.
The electrostatic spinning process and the spinning conditions are optimized, and the composite nanofiber with better piezoelectric performance can be prepared by a method of adding functional nano materials into the spinning solution. By adding nano-filler, negative surface charge is filledThe material may be-CH with PVDF 2 Group interaction, positively surface charged Filler with-CF of PVDF 2 The group interaction enhances the interface coupling effect, thereby being beneficial to inducing the generation of the polar beta phase and improving the piezoelectric performance. Alternatively, using filler particles (e.g. BaTiO) 3 ZnO) itself can also enhance the piezoelectric response of the composite. Common nano filling materials include graphene, carbon nano tube and BaTiO 3 ZnO and MnO 2 And the like.
CN101314869A (a device and a spinning method for preparing polymer nanofibers) utilizes the drafting effect of electrostatic field force to prepare polymer nanofibers such as polyvinylidene fluoride (PVDF). A macromolecular solution prepared from a macromolecular material is contained in a spinneret tube, and the macromolecular solution is heated to a preset temperature through a temperature feedback controller; and loading voltage, enabling the polymer nano-fibers to flow out from the nozzle under the action of the electric field force, and collecting the polymer nano-fibers on a receiving plate. Similarly, CN105037761a (a method for preparing a polyvinylidene fluoride nano-film with a β crystal phase) prepares a PVDF nano-film with a β crystal phase by doping graphene oxide GO, dissolving graphene oxide and polyvinylidene fluoride in an organic solvent, and performing ultrasonic and magnetic stirring to obtain a uniformly dispersed film-making solution; then standing the film preparation solution for defoaming; preparing a wet film by adopting a spin-coating method; finally, the film is dried and crystallized by heat treatment in the atmospheric environment, and the polyvinylidene fluoride nano film with the beta crystalline phase is prepared. On one hand, the content of a beta crystalline phase in PVDF is improved by doping GO, and on the other hand, a spin coating process is adopted to prepare a PVDF nano film; the preparation process is simple and the cost is low.
It should be noted that although the PVDF piezoelectric performance can be improved by electric field polarization of electrostatic field force or by filler doping, in order to ensure good compatibility between the nanoparticles and the PVDF, a complicated and troublesome particle surface modification process is generally required, which is not favorable for large-scale industrial production of the composite material. In addition, the introduction of the conductive particles such as the carbon nanotube and the graphene can also greatly reduce the electric field breakdown strength of the composite material, so that the polarization electric field of the composite material is small, sufficient polarization cannot be obtained, and the improvement range of the piezoelectric performance is limited. The electrodes commonly used in the piezoelectric transduction and sensing device are metal or carbon materials with two-dimensional structures and can only be contacted with fibers on the surface of the piezoelectric nanofiber mesh film. Therefore, when the nanofiber omentum generates piezoelectric charges, only the charges generated by the nanofibers on the surface of the omentum can be transferred to the electrode to output a piezoelectric signal. Meanwhile, the piezoelectric charges can be generated simultaneously by the internal fibers occupying most of the nanofiber net membrane, but the charges cannot be effectively transferred because the charges are not in contact with the electrodes, so that the output of a piezoelectric signal is greatly limited. Therefore, another way is needed to construct a three-dimensional electrode structure that can contact the piezoelectric nanofibers within the surface layer of the omentum, so as to more effectively realize charge transfer after the piezoelectric charges are generated, thereby improving the energy conversion efficiency.
Disclosure of Invention
In order to solve the technical problem, the invention provides a flexible piezoelectric nanofiber net film, which comprises a conductive thin film layer, a composite nanofiber net film layer and a spinning polymer nanofiber net film layer; the composite nanofiber mesh film layer is arranged between the spinning polymer nanofiber mesh film layer and the conductive film layer to form a laminated structure, as shown in fig. 4;
the composite nanofiber mesh film layer comprises a spinning polymer and a conductive substance, and is obtained by simultaneously performing electrostatic spinning on the spinning polymer and electrostatic spraying on the conductive substance;
the conductive substance and the conductive film layer are both made of Ti 3 C 2 One or more of graphene oxide, silver and carbon nanotubes.
Preferably, the spinning polymer is polyvinylidene fluoride, poly (vinylidene fluoride-trifluoroethylene) copolymer, polyvinyl fluoride, polyvinyl chloride, poly-gamma-methyl-L-glutamate or nylon-11.
Preferably, a composite laminate structure, as shown in FIG. 5; the composite nanofiber net film layer consists of a composite film I and a composite film II, and the conductive film layer consists of a conductive film I and a conductive film II; the composite membrane I is arranged between the conductive membrane I and the spinning polymer nanofiber mesh membrane layer, the composite membrane II is arranged between the conductive membrane II and the spinning polymer nanofiber mesh membrane layer, and the spinning polymer nanofiber mesh membrane layer is arranged between the composite membrane I and the composite membrane II.
Preferably, the thickness ratio of the conductive film layer, the composite nanofiber mesh film layer and the spinning polymer nanofiber mesh film layer is as follows: 0.01-0.1:0.2-3:1.
the invention also provides a preparation method of the flexible piezoelectric nanofiber mesh film, which comprises the following steps:
s1: respectively preparing a conductive substance dispersion liquid and a spinning polymer electrospinning liquid;
s2: carrying out electrostatic spinning on the spinning polymer electrospinning solution to obtain a spinning polymer nanofiber net film layer;
s3: simultaneously carrying out electrostatic spinning and electrostatic spraying on the surface of the spinning polymer nanofiber mesh film to obtain a well-coated and continuous conductive layer on the surface of the nanofiber; the raw material of electrostatic spinning is spinning polymer electrospinning liquid, and the raw material of electrostatic spraying is conductive substance dispersion liquid;
s4: and continuously electrostatically spraying conductive substance dispersion liquid on the surface of the multilayer film structure to obtain the flexible piezoelectric nanofiber net film.
Preferably, the dispersion medium in the conductive substance dispersion liquid is one or more of ethanol, acetone, tetrahydrofuran, methanol, and chlorotrifluoroethylene.
Preferably, the conductive substance dispersion is prepared by adding the conductive substance to a corresponding solvent and performing ultrasonic treatment to uniformly disperse the conductive substance.
Preferably, the solvent of the spinning polymer electrospinning solution is one or more of dimethylformamide, water, tetrahydrofuran, ethanol and acetone.
Preferably, in step S3, the conditions of electrospinning are as follows: the voltage is 8-18kV, and the injection speed is 1-2mL/h.
Preferably, in step S3, the electrostatic spraying conditions are as follows: the voltage is 12-25kV, and the injection speed is 10-50mL/h.
Specifically, in the step S3, the electrostatic spinning is performed by sucking the electrostatic spinning solution into an injector and placing the injector into a micro injection pump, wherein a needle point of the liquid supply device is connected with a direct-current high-voltage positive electrode, and a receiving device connected with a direct-current high-voltage negative electrode is placed at a position 10-20cm away from the needle point in the vertical direction; under a high-voltage electric field, the electrospinning liquid drops overcome the surface tension to form a jet trickle, further form a fiber membrane, and are collected to a receiving roller, wherein the rotating speed of the receiving roller is 400-1000r/min.
Specifically, in the step S3, the electrostatic spraying is performed by sucking the conductive substance dispersion liquid into an injector at the other end and placing the syringe into a micro injection pump, wherein a needle point of the liquid supply device is connected with a direct-current high-voltage positive electrode, the distance from the roller receiving device to the needle point in the spraying direction is 5-8cm, and the concentration of the conductive substance dispersion liquid is 5-20mg/mL.
The invention also provides a piezoelectric transducer which comprises the flexible piezoelectric nanofiber net film.
Preferably, the device also comprises a bottom layer copper foil electrode and a top layer copper foil electrode; the bottom copper foil electrode and the top copper foil electrode are respectively arranged on two sides of the flexible piezoelectric nanofiber net film.
At present, most of electrodes are two-dimensional electrodes, conductive electrodes are directly attached on the basis of original piezoelectric materials, and the conductive charges led out of the electrodes are limited on the surfaces of the piezoelectric materials. Therefore, the invention utilizes the electrostatic spraying method to coat the conductive nano material on the surface of the PVDF nano fiber, utilizes the high conductivity of the conductive nano material to conduct the charge generated in the PVDF piezoelectric material, increases the output voltage under the condition of unchanged pressure and stress area, and improves the piezoelectric performance.
Compared with the prior art, the technical scheme of the invention has the following advantages:
(1) MXene nanosheets are synchronously and controllably tightly coated on the surface of the nanofiber through a synchronous electrostatic spinning/electrostatic spraying process, and a three-dimensional electrode structure is constructed on the piezoelectric nanofiber net film;
(2) The piezoelectric nanofiber membrane electrode structure has the advantages that the energy conversion efficiency of the piezoelectric nanofibers is improved from the different electrode angles, the effective contact between the piezoelectric nanofibers and the electrode of a transducer is optimized by utilizing a three-dimensional electrode structure constructed on the nanofiber membrane, and the mobility of piezoelectric electrostatic charges and the piezoelectric signal output are improved.
Drawings
FIG. 1 shows SEM pictures of PVDF/MXene composite nanofibers (a) and PVDF nanofibers (b).
Fig. 2 is a cross-sectional SEM picture of a three-dimensional electrode structure.
FIG. 3 is a diagram of a three-dimensional flexible electrode electrospinning apparatus.
Fig. 4 is a schematic structural diagram of a single-sided three-dimensional electrode piezoelectric nanofiber transducer.
Fig. 5 is a structural schematic diagram of a double-sided three-dimensional electrode piezoelectric nanofiber transducer.
FIG. 6 shows piezoelectric output results of a single-sided three-dimensional electrode PVDF/MXene composite nanofiber mesh membrane nanofiber piezoelectric transducer.
FIG. 7 shows the piezoelectric output results of pure PVDF fiber piezoelectric transducers.
FIG. 8 shows piezoelectric output results of a single-sided three-dimensional electrode PVDF/CNT composite nanofiber mesh membrane nanofiber piezoelectric transducer.
FIG. 9 is a piezoelectric output result of a single-sided three-dimensional electrode PVDF/GO composite nanofiber mesh membrane nanofiber piezoelectric transducer.
FIG. 10 is a double-sided three-dimensional electrode PVDF/MXene composite nanofiber mesh membrane nanofiber piezoelectric transducer.
Description of reference numerals: 1-a top copper foil electrode, 2-a conductive film layer, 3-a composite nanofiber net film layer, 4-a spinning polymer nanofiber net film layer and 5-a bottom copper foil electrode.
Detailed Description
The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.
The invention provides a piezoelectric transducer of a PVDF/MXene composite flexible piezoelectric nanofiber net film, which comprises a top copper foil electrode 1 and a bottom copper foil electrode 5, and further comprises a conductive film layer 2, a composite nanofiber net film layer 3 and a spinning polymer nanofiber net film layer 4 for better connection with test equipment so as to improve the contact effect of electrodes, wherein a three-dimensional electrode structure exists in the composite nanofiber net film layer 3, as shown in figure 4; finally, the device can be fixed and packaged on two sides by utilizing PET films and the like.
The invention also provides a piezoelectric transducer of the PVDF/MXene composite flexible piezoelectric nanofiber net film, which comprises a top copper foil electrode 1 and a bottom copper foil electrode 5 as shown in figure 5, wherein composite nanofiber net film layers 3 are arranged on two sides of a spinning polymer nanofiber net film layer 4; and a conductive film layer 2 is also arranged on the outer side of the composite nanofiber net film layer 3.
Example 1
1. Preparation of MXene (Ti) 3 C 2 ) And (3) dispersing, namely adding the MAX precursor and lithium fluoride into 9mol of hydrochloric acid, wherein the ratio of the MAX precursor to the lithium fluoride is 1. Placing the mixture into a polytetrafluoroethylene beaker, and heating and reacting for 24-18h at 40 ℃ by magnetic stirring. Washing with deionized water to neutral, manually oscillating, dispersing and centrifuging to obtain MXene, adding ethanol as solvent to obtain Ti 3 C 2 The dispersion was electrostatically sprayed.
2. Adding 4mL of DMF and 6mL of acetone into a beaker, uniformly mixing, adding 2.2g of PVDF into the solution, magnetically stirring for 3 hours at the rotating speed of 800rpm and the temperature of 60 ℃ to obtain the PVDF electrostatic spinning solution.
3. Spraying PVDF electrostatic spinning solution on an electrostatic spinning machine roller aluminum foil collecting device. The rotating speed is 400r/min, the distance between the needle and the collecting device is about 15cm, the high-voltage power supply is 8.5kV, the spraying liquid amount is 2mL, and the propelling speed of the injection pump is 1mL/h.
4. After 2 hours, continuously spraying PVDF electrostatic spinning solution, and introducing Ti on the other side of the collecting roller 3 C 2 Electrostatic spraying of the dispersion to form PVDF/Ti 3 C 2 The needle point of the composite nano fiber net film layer is about 6cm from the level of the collection device, the high-voltage power supply is 18kV, the spraying liquid amount is 30mL, and the propelling speed of the injection pump is 30mL/h.
5. After the spraying of the composite nanofiber net film layer is finished, the electrostatic spinning of the PVDF end is temporarily closed, and Ti spraying is continued 3 C 2 Spraying the dispersion with 18kV high voltage power supply for 10min to form MXene film.
6. To be Ti 3 C 2 After the layer spraying is finished, closing Ti 3 C 2 And (4) carrying out electrostatic spraying and closing the electrostatic spinning device.
7. Cutting the piezoelectric fiber film to 3 x 3cm 2 And (3) using copper sheets as electrodes on two sides, connecting the electrodes by using lead wires, and then packaging the electrodes by using a PET film, wherein the thickness of the PET film is 38 mu m, and finally obtaining the single-side three-dimensional electrode PVDF/MXene composite nanofiber mesh film layer nanofiber piezoelectric transducer, wherein the piezoelectric output result is shown in figure 6, the open-circuit voltage reaches 2.43V, and the short-circuit current reaches 0.29 mu A. The pure PVDF of FIG. 7 has an open circuit voltage of 1.61V and a short circuit current of 0.18. Mu.A, measured under the same conditions.
Example 2
1. Preparing CNT dispersion, firstly adding multi-wall carbon nano-tubes into 1mol of HCl to remove impurities for 24h at the temperature of 60 ℃, then mixing with a mixed solution of nitric acid (69%) + concentrated sulfuric acid (90%) with the volume ratio of 1:3, oxidizing for 3h at the temperature of 60 ℃, washing with a large amount of deionized water, filtering and drying to obtain the acid-washed CNT powder. Adding 100mg of the acid-washed CNT into 50mL of ethanol solution, preparing 2mg/mL CNT dispersion, magnetically stirring for 10min, and then putting into an ultrasonic cleaning machine for ultrasonic treatment for 40min.
2. Adding 4mL of DMF and 6mL of acetone into a beaker, uniformly mixing, adding 2.2g of PVDF into the solution, magnetically stirring for 3 hours at the rotating speed of 800rpm and the temperature of 60 ℃ to obtain the PVDF electrostatic spinning solution.
3. Firstly spraying PVDF electrostatic spinning solution on an electrostatic spinning machine roller aluminum foil collecting device. The rotating speed is 400r/min, the distance between the needle head and the collecting device is about 15cm, the high-voltage power supply is 8.5kV, the spraying liquid amount is 2mL, and the propelling speed of the injection pump is 1mL/h.
4. After 2h, continuously spraying PVDF electrostatic spinning solution, introducing CNT dispersion solution on the other side of the collecting roller for electrostatic spraying to form a PVDF/CNT composite nano-fiber net film layer, wherein the needle point is about 6cm away from the level of the collecting device, the high-voltage power supply is 20kV, the spraying solution amount is 40mL, and the propelling speed of the injection pump is 40mL/h.
5. And after the spraying of the composite nanofiber mesh film layer is finished, closing the electrostatic spinning at the PVDF end temporarily, and continuously spraying the CNT dispersion liquid with a high-voltage power supply of 18kV for 15min to form a pure CNT film layer.
6. And after the CNT layer is sprayed, closing the electrostatic spraying of the CNT end, and closing the electrostatic spinning device.
7. Cutting the piezoelectric fiber film to 3 x 3cm 2 And (3) using copper sheets as electrodes on two sides, connecting the electrodes by using lead wires, and then packaging the electrodes by using a PET film, wherein the thickness of the PET film is 38 mu m, and finally obtaining the single-side three-dimensional electrode PVDF/CNT composite nanofiber mesh film layer nanofiber piezoelectric transducer. The piezoelectric output results are shown in FIG. 8, where the open-circuit voltage reached 2.37V and the short-circuit current reached 0.42 μ A.
Example 3
1. Preparing Graphene Oxide (GO) dispersion, firstly adding 50mg of GO powder into 10mL of aqueous solution, performing probe ultrasonic treatment for 10min by using a cell crusher, and then adding 40mL of ethanol solution to prepare 1mg/mL of graphene oxide dispersion.
2. Adding 4m of DMF and 6mL of acetone into a beaker, uniformly mixing, adding 2.2g of PVDF into the solution, magnetically stirring for 3 hours at the rotating speed of 800rpm and the temperature of 60 ℃ to obtain the PVDF electrostatic spinning solution.
3. Firstly spraying PVDF electrostatic spinning solution on an electrostatic spinning machine roller aluminum foil collecting device. The rotating speed is 400r/min, the distance between the needle head and the collecting device is about 15cm, the high-voltage power supply is 8.5kV, the spraying liquid amount is 2mL, and the propelling speed of the injection pump is 1mL/h.
4. After 2h, continuously spraying PVDF electrostatic spinning solution, introducing GO dispersion solution on the other side of the collecting roller for electrostatic spraying to form a PVDF/GO composite nano-fiber net film layer, wherein the needle point is about 6cm away from the level of the collecting device, the high-voltage power supply is 20kV, the spraying solution amount is 40mL, and the propelling speed of the injection pump is 40mL/h.
5. After the spraying of the composite nanofiber net film layer is finished, the PVDF end electrostatic spinning is temporarily closed, GO dispersion liquid continues to be sprayed, the high-voltage power supply is 18kV, and the spraying is carried out for 15min, so that a GO thin film layer is formed.
6. And after finishing the spraying of the GO layer, closing the electrostatic spraying of the GO end and closing the electrostatic spinning device.
7. Cutting the piezoelectric fiber film to 3 x 3cm 2 The two sides of the lead are made of copper sheets as electrodes and lead wiresAnd packaging the obtained product by using a PET film, wherein the thickness of the PET film is 38 mu m, and finally obtaining the single-side three-dimensional electrode PVDF/GO composite nanofiber mesh film layer nanofiber piezoelectric transducer. The piezoelectric output results are shown in FIG. 9, where the open-circuit voltage was 2.01V and the short-circuit current was 0.27. Mu.A.
Example 4
1. Preparation of MXene (Ti) 3 C 2 ) Dispersing liquid, adding MAX precursor and lithium fluoride into 9mol hydrochloric acid, wherein the ratio of MAX precursor to lithium fluoride is 1. Placing the mixture into a polytetrafluoroethylene beaker, and heating and reacting for 24-18h at 40 ℃ by magnetic stirring. Washing with deionized water to neutrality, manually oscillating, dispersing, centrifuging to obtain MXene, adding ethanol as solvent to obtain Ti 3 C 2 The dispersion was electrostatically sprayed.
2. Adding 4mL of DMF and 6mL of acetone into a beaker, uniformly mixing, adding 2.2g of PVDF into the solution, magnetically stirring for 3 hours at the rotating speed of 800rpm and the temperature of 60 ℃ to obtain the PVDF electrostatic spinning solution.
3. Ti is firstly carried out on an electrostatic spinning machine roller aluminum foil collecting device 3 C 2 And (3) carrying out electrostatic spraying on the dispersion liquid, wherein a high-voltage power supply is 18kV, and spraying is carried out for 10min to form the MXene film.
4. Then simultaneously opening an electrostatic spinning and electrostatic spraying device to prepare PVDF/Ti 3 C 2 The needle point of the composite nano fiber net film layer is about 6cm from the level of the collection device, the high-voltage power supply is 18kV, the spraying liquid amount is 30mL, and the propelling speed of the injection pump is 30mL/h. The distance between the needle head and the collecting device is about 15cm, the high-voltage power supply is 8.5kV, the spraying liquid amount is 1mL, and the propelling speed of the injection pump is 1mL/h.
5. After 1h, the Ti is turned off 3 C 2 And (3) end electrostatic spraying, continuing to perform PVDF electrostatic spinning at the rotating speed of 400r/min, the distance between the needle head and the collecting device is about 15cm, the high-voltage power supply is 8.5kV, the spraying liquid amount is 2mL, and the propelling speed of the injection pump is 1mL/h.
6. After 2h, continuously opening Ti 3 C 2 End electrostatic spraying to prepare PVDF/Ti on the other side 3 C 2 The needle point of the composite nano fiber net film layer is about 6cm from the level of the collection device, the high-voltage power supply is 18kV, the spraying liquid amount is 30mL, and the propelling speed of the injection pump is 30mL/h.
5. After the spraying of the composite nanofiber net film layer is finished, the electrostatic spinning of the PVDF end is temporarily closed, and Ti spraying is continued 3 C 2 Spraying the dispersion liquid at 18kV for 10min to form the MXene film.
6. To be Ti 3 C 2 After the layer is sprayed, the Ti is turned off 3 C 2 And (5) carrying out electrostatic spraying, and closing the electrostatic spinning device.
7. Cutting the piezoelectric fiber film to 3 x 3cm 2 And (3) using copper sheets as electrodes on two sides, connecting the electrodes by using leads, and packaging the electrodes by using a PET film, wherein the thickness of the PET film is 38 mu m, and finally obtaining the double-sided three-dimensional electrode PVDF/MXene composite nanofiber net film layer nanofiber piezoelectric transducer. The piezoelectric output results are shown in fig. 10, and the open-circuit voltage and the short-circuit current were measured to be 4.28V and 0.47 μ a, respectively.
According to the invention, the PVDF nanofiber surface is pasted with the conductive nanomaterial to construct the three-dimensional conductive electrode, so that charges generated in the flexible piezoelectric material due to deformation caused by mechanical external force are collected successfully, and charge transfer is realized more effectively, thus the energy conversion efficiency is improved and the piezoelectric performance is improved under the condition of the same thickness. The PVDF/MXene composite nanofiber mesh membrane layer nanofiber mesh membrane with the single-sided three-dimensional electrode is prepared by spraying the conductive nanomaterial MXene on the surface of the PVDF nanofiber, and the output voltage is 1.61V and the output current is 0.29 muA, which are 50.9% higher than the output voltage of 2.43V measured by pure PVDF under the same condition and 61.1% higher than the output current of 0.18 muA. And the double-sided three-dimensional electrode PVDF/MXene composite nanofiber mesh membrane layer nanofiber mesh membrane is designed and prepared, and the open-circuit voltage and the short-circuit current of the double-sided three-dimensional electrode PVDF/MXene composite nanofiber mesh membrane layer nanofiber mesh membrane are measured to be 4.28V and 0.47 muA respectively.
The preparation method comprises the steps of taking conductive nano materials (MXene) and PVDF as raw materials, adopting a synchronous electrostatic spinning/electrostatic spraying device (figure 3), carrying out PVDF electrostatic spinning at one end of the synchronous device, and carrying out MXene two-dimensional nanosheet electrostatic spraying at the other end of the synchronous device so as to realize uniform coating of MXene nanosheets on the surface of a single nanofiber and form a conductive path, thus obtaining the three-dimensional structure electrode (figure 1). The optimal parameters can be found by controlling the size, concentration and distribution quantity of the MXene sheets, and the transducer can respond to the change of different pressures and show different electric signals under different pressures and frequencies. Fig. 1 is a SEM picture of PVDF electrospun nanofiber, on which MXene highly conductive nanosheets are not coated.
In order to better observe the three-dimensional electrode structure constructed by the two-dimensional MXene nanosheets, N 2 And (3) performing high-temperature treatment in an atmosphere tubular furnace to remove the PVDF nano-fiber to obtain the pure MXene three-dimensional structure which is independent and flaky. As shown in the cross-sectional SEM picture of the three-dimensional electrode in fig. 2, it can be seen that the three-dimensional electrode structure has a large number of circular hole structures, which should be formed after the MXene-coated nanofibers are removed by the high-temperature treatment. MXene nano sheets in the three-dimensional structure are mutually communicated, so that a novel porous electrode is constructed.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (10)
1. The flexible piezoelectric nanofiber net film is characterized by comprising a conductive thin film layer (2), a composite nanofiber net film layer (3) and a spinning polymer nanofiber net film layer (4); the composite nanofiber net film layer (3) is arranged between the spinning polymer nanofiber net film layer (4) and the conductive film layer (2);
the composite nanofiber net film layer (3) comprises a spinning polymer and a conductive substance, and is obtained by simultaneously performing electrostatic spinning on the spinning polymer and electrostatic spraying on the conductive substance;
the conductive substance and the conductive film layer (2) are both made of Ti 3 C 2 One or more of graphene oxide, silver nanowires, and carbon nanotubes.
2. The flexible piezoelectric nanofiber web according to claim 1, wherein the composite nanofiber web membrane layer (3) is symmetrically arranged on two sides of the spun polymer nanofiber web membrane layer (4); the conductive film layers (2) are symmetrically arranged on one side, away from the spinning polymer nanofiber net film layer (4), of the composite nanofiber net film layer (3).
3. The flexible piezoelectric nanofiber web as claimed in claim 1, wherein the thickness ratio of the conductive thin film layer (2), the composite nanofiber web film layer (3) and the spun polymer nanofiber web film layer (4) is: 0.01-0.1:0.2-3:1.
4. a method of making a flexible piezoelectric nanofiber web according to claim 1, comprising the steps of:
s1: respectively preparing a conductive substance dispersion liquid and a spinning polymer electrospinning liquid;
s2: carrying out electrostatic spinning on the spinning polymer electrospinning solution to obtain a spinning polymer nanofiber net film layer;
s3: carrying out electrostatic spinning and electrostatic spraying on the surface of the spinning polymer nanofiber net film layer simultaneously to obtain a multilayer film structure; the raw material of electrostatic spinning is spinning polymer electrospinning liquid, and the raw material of electrostatic spraying is conductive substance dispersion liquid;
s4: and continuously electrostatically spraying conductive substance dispersion liquid on the surface of the multilayer film structure to obtain the flexible piezoelectric nanofiber net film.
5. The method according to claim 4, wherein the dispersion medium in the conductive substance dispersion liquid is one or more of ethanol, acetone, tetrahydrofuran, methanol, and chlorotrifluoroethylene.
6. The method of claim 4, wherein the solvent of the spinning polymer dope is one or more of dimethylformamide, water, tetrahydrofuran, ethanol, and acetone.
7. The method of claim 4, wherein in the step S3, the conditions of electrospinning are: the voltage is 8-18kV, and the injection speed is 1-2mL/h.
8. The production method according to claim 4, wherein in the step S3, the electrostatic spraying conditions are: the voltage is 12-25kV, and the injection speed is 10-50mL/h.
9. A piezoelectric transducer comprising the flexible piezoelectric nanofiber web of any one of claims 1 to 3.
10. The piezoelectric transducer of claim 9, further comprising a bottom layer copper foil electrode and a top layer copper foil electrode; the bottom layer copper foil electrode and the top layer copper foil electrode are respectively arranged on two sides of the flexible piezoelectric nanofiber net film.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115724460A (en) * | 2022-11-11 | 2023-03-03 | 西安电子科技大学 | Friction nanometer generator based on perovskite material and preparation method thereof |
| CN117602712A (en) * | 2024-01-09 | 2024-02-27 | 兰州交通大学 | MXene-based three-dimensional particle electrode in electrolyte-free drinking water catalytic purification and preparation method thereof |
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| US20170331027A1 (en) * | 2014-12-02 | 2017-11-16 | Industry-University Cooperation Foundation Hanyang University | Piezoelectric fiber having excellent flexibility and elasticity, and method for manufacturing the same |
| KR20190142585A (en) * | 2018-06-18 | 2019-12-27 | 울산과학기술원 | Three-dimensional porous-structured electrode, methode of manufacturing and electrochemical device having the electrode |
| CN112918031A (en) * | 2021-01-26 | 2021-06-08 | 清华大学 | High-dielectric-elasticity composite material and preparation method and application thereof |
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| US20170331027A1 (en) * | 2014-12-02 | 2017-11-16 | Industry-University Cooperation Foundation Hanyang University | Piezoelectric fiber having excellent flexibility and elasticity, and method for manufacturing the same |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115724460A (en) * | 2022-11-11 | 2023-03-03 | 西安电子科技大学 | Friction nanometer generator based on perovskite material and preparation method thereof |
| CN115724460B (en) * | 2022-11-11 | 2023-12-01 | 西安电子科技大学 | Friction nano generator based on perovskite material and preparation method thereof |
| CN117602712A (en) * | 2024-01-09 | 2024-02-27 | 兰州交通大学 | MXene-based three-dimensional particle electrode in electrolyte-free drinking water catalytic purification and preparation method thereof |
| CN117602712B (en) * | 2024-01-09 | 2024-04-19 | 兰州交通大学 | MXene-based three-dimensional particle electrode in electrolyte-free drinking water catalytic purification and preparation method thereof |
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