High-temperature-resistant bifunctional nanogenerator material, preparation method and application thereof

Abstract

The application discloses a kind of high-temperature-resistant bifunctional nanogenerator materials and preparation method and application thereof, belong to high-temperature-resistant sensitive material development field;Solve the poor flexibility, single function and lead toxicity of traditional high-temperature piezoelectric sensor and other problems;The application is that piezoelectric polymer polyacrylonitrile and anhydrous acetate are fully mixed in organic solvent and pre-cyclization, then the method of electrospinning is used to prepare flexible nanofiber membrane, and the composite fiber membrane is heat treated, and nanogenerator material is prepared;The nanogenerator material described in the application can work continuously in an environment higher than 450 DEG C, has pyroelectric function, has dual sensitivity to force and heat, and has good flexibility.The preparation method is simple, low cost, environment-friendly and excellent in electrical output performance, and is expected to have good application prospect in the field of force and heat sensitive signal monitoring and sensing in extreme high-temperature environment.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature sensitive material development, specifically relating to a high-temperature resistant piezoelectric / pyroelectric bifunctional flexible nanomaterial based on anhydrous zinc acetate doping or anhydrous zinc acetate and multi-walled carbon nanotube doping, its preparation method and application. Background Technology

[0002] Devices made from high-temperature resistant sensitive materials have wide applications in harsh testing environments such as oil well drilling, natural gas, automotive industry, nuclear power, and aerospace. The multifunctional behavior of inorganic piezoelectric and pyroelectric materials influences many fields, but their fragility and toxicity severely hinder their development in the field of flexible high-temperature resistant materials. Therefore, organic high-temperature flexible sensitive materials are of extremely important research significance.

[0003] Traditional high-temperature piezoelectric sensors are made entirely of high-temperature piezoelectric ceramics and high-temperature piezoelectric single crystal materials, which are all rigid. Their application and stability are limited by factors such as low stress, poor flexibility, the toxicity of lead-containing piezoelectric materials, and low electrical output power. Meanwhile, conventional flexible piezoelectric materials have low operating temperatures. Commonly used polymer piezoelectric materials include polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN), but PVDF's operating temperature range limits its application in high-temperature environments, while heat-treated pure PAN is prone to cracking. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and proposes a method for preparing high-temperature resistant bifunctional nanomaterials for generating electricity.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for preparing a high-temperature resistant bifunctional nanomaterial for generating electricity includes the following steps:

[0007] 1) Preparation of precyclized precursor solution: 10-15% by mass of polyacrylonitrile and 1-5% by mass of anhydrous acetate are added to N,N-dimethylformamide. The mixture is first cooled to -3-5℃ and stirred for 1-3 hours, then heated to 60-80℃ and stirred for 3-6 hours to obtain polyacrylonitrile-anhydrous acetate precursor solution.

[0008] Low-temperature stirring makes the solution more stable; heating and stirring allows polyacrylonitrile (PAN) to undergo pre-cyclization.

[0009] 2) The precursor solution was electrospun to obtain a fiber membrane;

[0010] 3) The fiber membrane is heat-treated to obtain the nano-power generation material. The heat treatment is to heat the fiber membrane at a heating rate of 1 to 5°C / min, and hold it for 20 to 60 minutes after each 40-60°C increase, until the fiber membrane is heated to 200-550°C.

[0011] Preferably, the N,N-dimethylformamide is further mixed with 0.05% to 0.1% by mass of a cyclizing material.

[0012] More preferably, the cyclization material is a multi-walled carbon nanotube, graphene oxide, lignin, silver nanoparticles, or cellulose nanocrystals.

[0013] More preferably, the cyclizing material and N,N-dimethylformamide are mixed by ultrasonic dispersion for 6-12 hours.

[0014] Preferably, the anhydrous acetate is anhydrous zinc acetate, anhydrous zirconium acetate, anhydrous potassium acetate, or anhydrous sodium acetate.

[0015] Preferably, the electrospinning voltage is 16-25KV, the stainless steel needle is 0.44mm, the solution flow rate is 0.5-1mL / h, the roller speed is 500-1200rpm, and the spinning distance is 5-20cm.

[0016] Preferably, in step 3), the temperature is increased by 50°C and then kept at that temperature for 20 to 60 minutes.

[0017] Preferably, when the temperature of heating the fiber membrane is 260°C or below, the process is carried out in an air atmosphere; when the temperature of heating is above 260°C, the process is carried out in a protective atmosphere.

[0018] Preferably, in step 3), the fiber membrane is heated to 260°C.

[0019] Preferably, the encapsulation of the prepared nano-power generation material includes a metal electrode and an insulating layer.

[0020] The high-temperature resistant bifunctional nanomaterial for power generation obtained by the preparation method is described above.

[0021] Application of high-temperature resistant bifunctional nanomaterials for power generation in devices that convert mechanical energy into electrical energy and thermal energy into electrical energy.

[0022] The beneficial effects of this invention compared to the prior art are as follows:

[0023] 1. Anhydrous zinc acetate is a metal salt. After doping, the carboxyl groups (-COOH) it contains can reduce the intermolecular forces in the PAN chain, forming π-π conjugation. This makes it easier for the helical conformation to transform into a planar zigzag conformation, which helps to lower the cyclization temperature and greatly improves the piezoelectric properties and flexibility. Furthermore, anhydrous zinc acetate decomposes at high temperatures to generate zinc oxide, which is a piezoelectric particle. The synergistic effect of heat treatment cyclization and zinc oxide can simultaneously enhance the piezoelectric effect.

[0024] 2. The introduction of multi-walled carbon nanotubes can lower the cyclization temperature and improve the piezoelectric properties of polyacrylonitrile by affecting its cyclization.

[0025] 3. In addition to possessing the high-temperature resistance of traditional high-temperature piezoelectric materials, this invention also exhibits great flexibility and dual piezoelectric / pyroelectric effects, making it a promising candidate for the fabrication of high-temperature resistant piezoelectric / pyroelectric dual-functional nanosensors.

[0026] 4. The high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterial for power generation proposed in this invention has a simple preparation process, good flexibility, stable operation at high temperatures, pyroelectric effect, and good piezoelectric properties, and has broad application prospects in the fields of high-temperature piezoelectric sensors and self-powered microelectronic devices.

[0027] 5. The method of this invention improves upon the problems of low strain, toxicity, and poor electrical output performance of previous high-temperature piezoelectric materials. It possesses advantages such as continuous operation at high temperatures, pyroelectric function, dual sensitivity to force and heat, and good flexibility. This invention significantly enhances the electrical output performance and flexibility of polymers, and exhibits both piezoelectric and pyroelectric effects, making it an ideal dual-functional flexible composite nanomaterial with high electrical output and high temperature resistance. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the preparation process of the high-temperature resistant piezoelectric / pyroelectric dual-functional flexible composite thin-film nanomaterial for generating electricity according to the present invention.

[0029] Figure 2 This is a diagram illustrating the pre-cyclization and cyclization mechanisms involved in the preparation process of the high-temperature resistant piezoelectric / pyroelectric flexible composite film of the present invention.

[0030] Figure 3 The images show the piezoelectric performance test results of the nanogenerators made from the nano-power generation materials prepared in Examples 1 and Comparative Example 1; where (3a) represents voltage output and (3b) represents current output.

[0031] Figure 4 This is a schematic diagram illustrating the foldability of the high-temperature resistant piezoelectric / pyroelectric flexible composite thin film nanofiber material of the present invention;

[0032] Figure 5 This is a graph showing the stable output of the film after heat treatment at 450℃ following doping with anhydrous Zn(Ac)2;

[0033] Figure 6 The diagram shows the pyroelectric voltage and current output of the film after heat treatment at 260℃ near heat sources at 350℃, 400℃ and 450℃; where (6a) is the voltage output and (6b) is the current output. Detailed Implementation

[0034] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0035] Example 1

[0036] (1) Preparation of PAN / Zn(Ac)2 solution

[0037] Weigh 12% PAN (polyacrylonitrile) and 5% Zn(Ac)2 using an electronic balance, and measure DMF (N,N-dimethylformamide) solution using a graduated cylinder. Place the measured PAN and zinc acetate into a three-necked flask, and then pour the DMF solution into the three-necked flask.

[0038] The three-necked flask was then fixed and connected to a cryogenic bath. The temperature was first lowered to 3°C and timed for 1 hour. Then, the temperature was raised to 80°C and stirred for 3 hours to obtain a homogeneous PAN / Zn(Ac)2 solution. The low-temperature stirring was to make the solution more stable, while the high-temperature stirring was to allow the polyacrylonitrile PAN to undergo pre-cyclization.

[0039] (2) Preparation of PAN / Zn(Ac)2 flexible composite film

[0040] The PAN / Zn(Ac)2 solution prepared in step (1) above was poured into a syringe, and then the syringe was fixed on an electrospinning machine equipped with a stainless steel needle (r = 0.41 mm). A series of parameters were set: the solution flow rate was 0.5 mL / h, the applied voltage was 18 KV, the distance between the steel needle and the grounded steel drum (20 cm in length and 10 cm in diameter) for collecting nanofibers and the rotation speed of the steel drum were 15 cm and 1000 rpm, respectively, and PAN / Zn(Ac)2 composite film was obtained by spinning.

[0041] (3) Preparation of high temperature resistant PAN / Zn(Ac)2 flexible composite film

[0042] Cut the PAN / Zn(Ac)2 composite film prepared in step (2) into a sample of a certain size, then peel off the tin foil and place it on a ceramic plate, and then fix its two ends with clips.

[0043] Then, heat treatment at different temperatures was carried out in a tube furnace, using a heating rate of 1–5 °C / min, with a holding time of 20–60 min after each 50 °C increase, allowing the composite film to undergo a series of reactions such as cyclization. Each heat treatment temperature included a heating stage and a holding stage. Specifically, under an air atmosphere, the temperature was raised to 50 °C and held for 30 min; then raised to 100 °C and held for 30 min; then raised to 150 °C and held for 30 min; then raised to 200 °C and held for 30 min; then raised to 250 °C and held for 30 min; finally, the temperature was raised to 260 °C and held for 30 min. Example 2

[0044] The only difference from Example 1 is that 0.05% to 0.1% by mass of multi-walled carbon nanotubes were added to the DMF (N,N-dimethylformamide) solution. The multi-walled carbon nanotubes and N,N-dimethylformamide were obtained by ultrasonic dispersion for 12 hours.

[0045] Example 3

[0046] The only difference from Example 1 is that the heat treatment involves raising the temperature to 260°C, then raising it to 300°C in a protective atmosphere and holding it for 30 minutes; then raising it to 350°C and holding it for 30 minutes; then raising it to 400°C and holding it for 30 minutes; and finally raising it to 450°C and holding it for 30 minutes, thus obtaining nano-power generation materials that have undergone different maximum temperatures.

[0047] Comparative Example 1

[0048] The only difference from Example 1 is that in step (1) there is only polyacrylonitrile (PAN) and no zinc acetate, and the voltage of electrospinning in step (2) is 22KV.

[0049] The high-temperature resistant piezoelectric / pyroelectric bifunctional flexible nanomaterials prepared in Examples 1 and Comparative Example 1 were used to fabricate nanogenerators. The piezoelectric properties of the fabricated nanogenerators were tested, and the test results are as follows: Figure 3 As shown, it can be seen that the generator prepared from the sample of nano-power generation material doped with anhydrous zinc acetate without heat treatment has better output performance; for the nano-power generation material prepared by heat treatment at 260℃, the generator prepared from the sample also doped with anhydrous zinc acetate has good output performance.

[0050] Comparative Example 2

[0051] The only difference from Example 1 is that the electrospinning technique is replaced by spin coating, with a rotation speed of 300-500 rpm, and then polarized by a polarizer with polarization parameters of 6 kV voltage and 180 min time.

[0052] The high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterial for generating electricity, prepared by Comparative Example 2, is extremely brittle after procedural heat treatment, so its piezoelectric output is not tested here.

[0053] Unless otherwise specified, the "%" in the embodiments of this invention refers to mass percentage.

[0054] The pre-cyclization and cyclization mechanism diagrams of the high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterials prepared in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown. By Figure 2 It can be seen that the addition of Zn(Ac)2 causes PAN to undergo pre-cyclization even without heat treatment. Furthermore, the carboxyl groups (-COOH) reduce the intermolecular forces within the PAN chain, forming π-π conjugation. This facilitates the transformation of the helical conformation into a planar zigzag conformation, which helps lower the cyclization temperature and significantly improves piezoelectric properties and flexibility. With increasing heat treatment temperature (>450℃), some PAN chains break, disrupting electron transport pathways and weakening electron transport capability, leading to a decrease in piezoelectric properties.

[0055] like Figure 4 As shown, for the high-temperature resistant piezoelectric / pyroelectric bifunctional flexible nanomaterials prepared in Example 1 and Comparative Example 1, Example 1 can be repeatedly folded, indicating that it has good flexibility.

[0056] like Figure 5 As shown, the stable piezoelectric output of the high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterial after heat treatment at 450℃ is measured in a 450℃ high-temperature environment. It can be seen that its piezoelectric performance has not weakened after 5000 impact cycles, and it can still reach an output voltage of about 15V. This indicates that it has good stability.

[0057] like Figure 6 As shown, this high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterial exhibits a pyroelectric effect, converting thermal energy into electrical energy, when near a heat source. Figure 6 The voltage and current outputs of the pyroelectric effect of the heat-treated thin film at 260℃ near heat sources at 350℃, 400℃, and 450℃ are respectively.

[0058] The piezoelectric material described in this invention is pyroelectric. It is produced by adding metal salts to pre-cyclize PAN, thereby reducing the cyclization temperature. The high temperature resistance, high voltage output performance, and flexibility of the piezoelectric material are improved by adding acetate to the spinning solution. It also has a dual piezoelectric / pyroelectric effect.

[0059] This invention utilizes anhydrous zinc acetate doping to pre-cyclize the spinning solution, lowering the cyclization temperature of PAN and promoting its cyclization. Furthermore, the carboxyl groups (-COOH) in anhydrous zinc acetate reduce the intermolecular forces of PAN, causing the helical conformation of PAN to transform into a planar zirconia conformation. Anhydrous zinc acetate decomposes at high temperatures to generate zinc oxide. In addition to the effect of anhydrous zinc acetate, multi-walled carbon nanotube doping also lowers the cyclization temperature and promotes cyclization. Further post-processing yields high-temperature resistant piezoelectric / pyroelectric materials.

[0060] In summary, the PAN / Zn(Ac)2 high-temperature resistant piezoelectric / pyroelectric dual-functional flexible nanomaterial for power generation provided in the specific embodiments of this invention not only operates stably and continuously in high-temperature environments but also possesses both piezoelectric and pyroelectric effects. This preparation method is simple and novel, and is conducive to the widespread application of high-temperature resistant piezoelectric / pyroelectric dual-functional flexible piezoelectric materials.

[0061] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all of these should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A method for preparing a high-temperature-resistant bifunctional nanogenerator material, characterized in that, Includes the following steps: 1) Preparation of precyclized precursor solution: 10-15% by mass of polyacrylonitrile and 1-5% by mass of anhydrous zinc acetate are added to N,N-dimethylformamide. The mixture is first cooled to -3-5℃ and stirred for 1-3 hours, and then heated to 60-80℃ and stirred for 3-6 hours to obtain polyacrylonitrile-anhydrous acetate precursor solution. 2) The precursor solution was electrospun to obtain a fiber membrane; 3) The fiber membrane is subjected to heat treatment to obtain the nano-power generation material. The heat treatment is carried out by heating the fiber membrane at a heating rate of 1 to 5°C / min, and holding the temperature for 20 to 60 minutes after each 40-60°C increase, until the fiber membrane is heated to 200-550°C. The N,N-dimethylformamide also contains 0.05% to 0.1% by mass of a cyclizing material, which is a multi-walled carbon nanotube. 2.The method for preparing a high-temperature-resistant bifunctional nanogenerator material according to claim 1, characterized in that, The cyclization material and N,N-dimethylformamide were mixed by ultrasonic dispersion for 6-12 hours.

3. The method for preparing a high-temperature resistant bifunctional nanomaterial for power generation according to claim 1, characterized in that, The electrospinning voltage is 16-25KV, the stainless steel needle is 0.44mm, the solution flow rate is 0.5-1mL / h, the drum speed is 500-1200rpm, and the spinning distance is 5-20cm. 4.The method of claim 1, wherein the method comprises the steps of: preparing a solution of a metal precursor and a reducing agent; and mixing the solution with a solution of a polymer and a surfactant to form a mixture; and heating the mixture to obtain the nano-generating material. In step 3), maintain the temperature for 20-60 minutes for every 50°C increase. 5.The method of claim 1, wherein the method further comprises the step of: 5-1) adding a reducing agent to the solution of step 4) to prepare the nano-generating material. When heating the fiber membrane to a temperature of 260°C or below, the process is carried out in an air atmosphere; when the heating temperature is above 260°C, the process is carried out in a protective atmosphere.

6. The high-temperature resistant bifunctional nanomaterial for generating electricity obtained by the preparation method according to any one of claims 1-5.

7. The application of the high-temperature resistant bifunctional nano-power generation material according to claim 6 in devices that convert mechanical energy into electrical energy and thermal energy into electrical energy.

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