High performance p(vdf-trfe)-based composite films and methods of making the same, nanogenerators containing the same

Abstract

High-performance P(VDF-TrFE) based composite film and preparation method thereof, and nanogenerator containing the composite film, the present application relates to piezoelectric composite material technical field, specifically relates to a kind of P(VDF-TrFE) / ZnO / CMWCNTs composite film and preparation method thereof, and piezoelectricity / friction electricity nanogenerator containing the composite film;The composite film is P(VDF-TrFE) / ZnO / CMWCNTs composite film, with P(VDF-TrFE) copolymer mass as benchmark, the addition amount of each component is as follows: P(VDF-TrFE) copolymer: TrFE molar content is 30%;ZnO nanoparticles: mass fraction is 0.36~1.80%;CMWCNTs: mass fraction is 0.01~0.03%;Overcome the technical defects, such as filler ratio out of control in existing P(VDF-TrFE) composite system, process parameter is not clear, piezoelectric property is low, and the output performance of nanogenerator based on it is poor, and stability is insufficient.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric composite material technology, specifically to a P(VDF-TrFE) / ZnO / CMWCNTs composite film and its preparation method, as well as a piezoelectric / triboelectric nanogenerator containing the composite film. Background Technology

[0002] The rapid iteration of flexible electronic devices and wearable smart technologies has placed higher demands on self-powered devices that combine high energy conversion efficiency, flexibility, and stability. Piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs) can efficiently harvest electrical energy from mechanical vibration, human motion, and environmental micromechanical energy, becoming the research frontier in the field of new energy materials [ACS Appl. Mater. Interfaces 2019, 11, 38177-38189].

[0003] Polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) copolymers are a core matrix material for the fabrication of flexible piezoelectric / triboelectric nanogenerators due to their excellent piezoelectric properties, good flexible processability, and environmental stability [Chemical Engineering Journal 2025, 510, 161818]. However, pure P(VDF-TrFE) films have low β-phase content, limited charge transport capacity, and a piezoelectric coefficient typically only 20–30 pC / N, with a remanent polarization value of less than 15 μC / cm. 2 However, the piezoelectric properties are difficult to meet the actual application requirements of high-performance devices. Therefore, improving their piezoelectric properties through filler compound modification has become a research focus [Applied Surface Science 2019, 463, 626-634].

[0004] However, the modification research of the P(VDF-TrFE) / ZnO / CNTs composite system still faces key technical bottlenecks in the existing technology: First, the addition range of ZnO and CNTs is not clear, and excessive addition can easily lead to filler agglomeration, significantly reducing the insulation and mechanical properties of the composite material; Second, the synergistic control mechanism of the preparation process parameters is unclear, and parameters such as the temperature and number of annealing and rolling processes have not been optimized, resulting in low β-phase content and chain segment orientation of the composite film; Third, the poor dispersibility of the fillers makes it impossible to achieve synergistic effects between inorganic piezoelectric fillers and conductive fillers, ultimately leading to low residual polarization and piezoelectric coefficient of the composite film. The output voltage of nanogenerators constructed based on this type of composite film is usually below 20V, and the power density is less than 10 μW / cm². 2 Its poor cycle stability limits its practical application in nanogenerators. Summary of the Invention

[0005] One objective of this invention is to overcome the technical defects of existing P(VDF-TrFE) composite systems, such as uncontrolled filler ratio, unclear process parameters, low piezoelectric performance, and poor output performance and insufficient stability of nanogenerators constructed based on them, and to provide a high-performance P(VDF-TrFE) / ZnO / CMWCNTs composite membrane and its preparation method, so as to solve at least one of the above-mentioned technical problems.

[0006] On one hand, the present invention provides a high-performance P(VDF-TrFE)-based composite membrane, wherein the composite membrane is a P(VDF-TrFE) / ZnO / CMWCNTs composite membrane, and the addition amount of each component is based on the mass of the P(VDF-TrFE) copolymer:

[0007] P(VDF-TrFE) copolymer: TrFE molar content is 30%;

[0008] ZnO nanoparticles: mass fraction 0.36~1.80%;

[0009] CMWCNTs: mass fraction of 0.01~0.03%.

[0010] In some embodiments, the composite film has an orientation degree of 0.66 and a remanent polarization value of 22 μC / cm. 2 The piezoelectric coefficient is 46 pC / N, and the piezoelectric performance shows no significant decay after 10,000 cycles of testing.

[0011] In some embodiments, the ZnO nanoparticles have a particle size of 30-45 nm, and the CMWCNTs conductive filler has an aspect ratio of 30-80.

[0012] On the other hand, the present invention provides a method for preparing a high-performance P(VDF-TrFE) based composite membrane, the method comprising the following steps:

[0013] (1) Preparation of casting solution: P(VDF-TrFE) copolymer was dissolved in DMF solvent and stirred until completely dissolved. Then ZnO nanoparticles and CMWCNTs were added and ultrasonically dispersed to form a uniform casting solution.

[0014] (2) Casting film: Casting solution is cast onto a clean glass plate, vacuum dried to remove solvent, and annealed to obtain an unrolled composite film;

[0015] (3) Hot rolling treatment: The unrolled composite film is hot rolled and then naturally cooled to room temperature to obtain the high-performance P(VDF-TrFE) / ZnO / CMWCNTs composite film.

[0016] In some embodiments, the mass fraction of the solution prepared by dissolving the P(VDF-TrFE) copolymer in DMF solvent in step (1) is 10%, and based on the mass of the P(VDF-TrFE) copolymer, the preferred contents of ZnO nanoparticles and CMWCNTs are 1.08 wt% and 0.02 wt%, respectively. The stirring temperature is 60°C, and the ultrasonic dispersion time is 45~55 min, preferably 50 min.

[0017] In some embodiments, the vacuum drying temperature in step (2) is 80°C, the drying time is 20 h, the annealing temperature is 140°C, and the annealing time is 2 h.

[0018] In some embodiments, the hot rolling temperature in step (3) is 25℃~100℃, the hot rolling is performed 5~7 times at a linear speed of 7 mm / s, the hot rolling temperature is preferably 90℃, and the hot rolling number is preferably 7 times.

[0019] The present invention also provides a piezoelectric / triboelectric nanogenerator, wherein the piezoelectric layer of the nanogenerator is the high-performance P(VDF-TrFE)-based composite film.

[0020] In some embodiments, a PET film is used as the positive triboelectric layer, a conductive adhesive is adhered to one side of the composite film as a positive electrode, the other side of the composite film is electrically connected to one end of the PET film through a conductive adhesive, and a conductive adhesive is adhered to the other side of the PET film as a negative electrode. The actual effective working area of ​​the device is 2.0 cm × 1.0 cm.

[0021] In some embodiments, the generator has an open-circuit voltage of up to 31 V and a maximum power density of 15.3 μW / cm². 2 A palm strike can drive at least 200 LEDs, and the output performance shows no significant degradation after 10,000 cycles of testing.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention precisely defines the mass fraction range and optimal ratio of ZnO nanoparticles and CMWCNTs, effectively avoiding filler agglomeration and achieving uniform dispersion of the two fillers in the P(VDF-TrFE) matrix. While improving the piezoelectricity and conductivity of the composite film, it maintains good insulation performance, achieving synergistic effects of the fillers. The resulting composite film has an orientation degree of 0.66 and a residual polarization of 22 μC / cm. 2 It has a piezoelectric coefficient of 46 pC / N, and its piezoelectric performance showed no significant decay after 10,000 cycles of testing.

[0024] 2. The key process parameters such as the temperature and number of hot rolling processes were optimized, which synergistically promoted the β-phase transformation and molecular chain orientation of the P(VDF-TrFE) matrix, significantly improving the overall piezoelectric properties of the composite film. The performance indicators are significantly better than those of existing P(VDF-TrFE) based composite films.

[0025] 3. The preparation process is simple, controllable, and highly repeatable. The casting solution dispersion, casting film formation, and hot rolling are all processes that are easy to implement in industrialization, requiring no complex equipment. It is suitable for large-scale production and has good industrialization prospects.

[0026] 4. The piezoelectric / triboelectric nanogenerator constructed based on the composite film of this invention achieves efficient synergy between the piezoelectric and triboelectric effects, resulting in a dual improvement in device output performance and cycle stability. This solves the problems of low energy conversion efficiency and limited practical applications of existing flexible energy harvesting devices. The device's open-circuit voltage can reach 31 V, and the maximum power density is 15.3 μW / cm². 2 After 10,000 cycles of testing, the output performance showed no significant degradation. A clap of the hand can easily light up more than 200 LEDs, and it has broad application prospects in flexible wearable electronics, self-powered sensors, and environmental mechanical energy harvesting.

[0027] 5. The nanogenerator has a simple structural design, convenient connection between the film and the electrode, good device flexibility and strong adaptability, and can be integrated with various flexible electronic devices, providing core material and device support for the development of self-powered flexible electronic systems. Attached Figure Description

[0028] Figure 1 This is a process flow diagram for preparing the P(VDF-TrFE) / ZnO / CMWCNTs composite membrane of the present invention;

[0029] Figure 2 The residual polarization values ​​(P) of composite films and unrolled films at different hot rolling temperatures are given. r Comparison chart;

[0030] Figure 3 The piezoelectric coefficients (d) of composite films and unrolled films at different hot rolling temperatures 33 Comparison chart;

[0031] Figure 4 The image shows the SEM morphology of the composite membrane prepared in Example 1 of this invention (ZnO nanoparticles and CMWCNTs are uniformly dispersed).

[0032] Figure 5 2D-WAXD diffraction pattern and orientation degree f of P(VDF-TrFE) / ZnO / CMWCNTs composite film hot-rolled at 90℃ H ;

[0033] Figure 6 The piezoelectric coefficient (d) of the composite membrane of this invention and the P(VDF-TrFE) based composite material reported in existing literature is... 33 ) and residual polarization (P r Comparison chart;

[0034] Figure 7 Here are schematic diagrams and physical images of the piezoelectric / triboelectric nanogenerator assembled with the composite membrane of this invention;

[0035] Figure 8 This is a diagram showing the 10,000-cycle test of the piezoelectric / triboelectric nanogenerator of this invention;

[0036] Figure 9 This diagram illustrates the practical application of the piezoelectric / triboelectric nanogenerator of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] The high-performance P(VDF-TrFE)-based composite membrane of this invention is a P(VDF-TrFE) / ZnO / CMWCNTs composite membrane. Based on the mass of the P(VDF-TrFE) copolymer, the addition amounts of each component are as follows:

[0039] P(VDF-TrFE) copolymer: TrFE molar content is 30%;

[0040] ZnO nanoparticles: mass fraction 0.36~1.80%;

[0041] CMWCNTs: mass fraction of 0.01~0.03%.

[0042] The composite film has an orientation degree of 0.66 and a remanent polarization value of 22 μC / cm. 2 The piezoelectric coefficient is 46 pC / N, and the piezoelectric performance shows no significant decay after 10,000 cycles of testing.

[0043] The ZnO nanoparticles have a particle size of 30~45 nm, and the CMWCNTs conductive filler has an aspect ratio of 30~80.

[0044] This invention precisely defines the mass fraction range and optimal ratio of ZnO nanoparticles and CMWCNTs, effectively avoiding filler agglomeration and achieving uniform dispersion of the two fillers in the P(VDF-TrFE) matrix. While improving the piezoelectricity and conductivity of the composite film, it maintains good insulation properties, achieving synergistic effects of the fillers. The resulting composite film has an orientation degree of 0.66 and a residual polarization of 22 μC / cm. 2 It has a piezoelectric coefficient of 46 pC / N, and its piezoelectric performance showed no significant decay after 10,000 cycles of testing.

[0045] Example 1

[0046] 1. Preparation of high-performance P(VDF-TrFE) / ZnO / CMWCNTs composite membranes

[0047] The specific steps are as follows:

[0048] (1) Preparation of casting solution: P(VDF-TrFE) copolymer with a molar content of 30% was dissolved in DMF solvent to prepare a solution with a mass fraction of 10% P(VDF-TrFE). The solution was stirred at 60°C until completely dissolved. Then, ZnO nanoparticles with a mass of 1.08 wt% of P(VDF-TrFE) and CMWCNTs with a mass of 0.02 wt% were added and ultrasonically dispersed for 50 min to form a uniform and non-agglomerated casting solution.

[0049] (2) Casting film: The above casting solution is uniformly cast on a clean and dry glass plate, placed in a vacuum drying oven at 80°C for 20 h to remove the solvent, and then annealed at 140°C for 2 h to obtain an unrolled composite film.

[0050] (3) Hot rolling treatment: The unrolled composite film is hot rolled 7 times at 90℃ and a linear speed of 7 mm / s. After hot rolling, it is naturally cooled to room temperature to obtain a high-performance P(VDF-TrFE) / ZnO / CMWCNTs composite film.

[0051] The composite film prepared in this embodiment underwent comprehensive performance testing, and its orientation degree reached 0.66, the relative fraction of β phase was 86.97%, and the remanent polarization value was 22 μC / cm. 2 With a piezoelectric coefficient of 46 pC / N, after 10,000 cycles of testing, the residual polarization and piezoelectric coefficient of the composite film showed no significant attenuation, and the piezoelectric performance remained stable.

[0052] 2. Fabrication and Performance Testing of Piezoelectric / Triboelectric Nanogenerators Based on Composite Films

[0053] The P(VDF-TrFE) / ZnO / CMWCNTs composite film prepared above was subjected to polarization treatment (polarization voltage: 11 kV; working distance: 1 cm; polarization temperature: 70℃; polarization time: 30 min) to construct the piezoelectric / triboelectric nanogenerator described in claim 6. Specifically, a conductive adhesive was adhered to one side of the composite film as a positive electrode, and a PET film was bonded to the other side as a positive triboelectric layer. One end of the composite film and the PET film were electrically connected by the conductive adhesive, and a conductive adhesive was adhered to the other side of the PET film as a negative electrode. The actual effective working area of ​​the device was 2.0 cm × 1.0 cm (see schematic diagram and physical image for details). Figure 7 ).

[0054] Performance tests on the nanogenerator showed that the piezoelectric and triboelectric effects of the device worked synergistically, with an open-circuit voltage of up to 31 V and a maximum power density of 15.3 μW / cm². 2 A simple clap of the hand can easily light up more than 200 LEDs. After 10,000 cycles of testing, the device's open-circuit voltage and power density showed no significant attenuation, its output performance remained stable, and its cycle stability was excellent, meeting the performance characteristics described in claim 7.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that no ZnO nanoparticles and CMWCNTs were added to the casting solution, and no hot rolling treatment was performed, while the other preparation conditions were exactly the same.

[0057] Comparative Example 2

[0058] The difference from Example 1 is that different mass fractions of ZnO nanoparticles (0.36, 0.72, 1.44, 1.80 wt%) were added to the casting solution, CMWCNTs were not added, and no hot rolling treatment was performed, while other preparation conditions were exactly the same.

[0059] The series of composite films prepared in this comparative example were tested. With the increase of ZnO nanoparticle addition, the β phase content and piezoelectric coefficient of the composite film first increased and then decreased. When the ZnO addition was 1.08 wt%, the piezoelectric coefficient reached 34 pC / N.

[0060] Comparative Example 3

[0061] The difference from Example 1 is that 1.08 wt% of ZnO nanoparticles were added to the casting solution, and different mass fractions of CMWCNTs (0.01 and 0.03 wt%) were added respectively. No hot rolling treatment was performed, and all other preparation conditions were exactly the same.

[0062] The series of composite membranes prepared in this comparative example were tested. When the amount of CMWCNTs added was 0.02 wt% (the ratio in Example 1), the piezoelectric coefficient of the composite membrane reached 35 pC / N. When the amount added was increased to 0.03 wt%, the filler agglomerated and the piezoelectric coefficient dropped to 26 pC / N.

[0063] Comparative Example 4

[0064] The difference from Example 1 is that the casting solution consists of 1.08 wt% ZnO nanoparticles and 0.02 wt% CMWCNTs, which are hot-rolled at 25, 50, 70 and 100°C respectively, while the other preparation conditions are exactly the same.

[0065] The series of composite films prepared in this comparative example were tested. When the hot rolling temperature was 90℃ (Example 1), the orientation degree, β phase content, remanent polarization value, and piezoelectric coefficient of the composite film all reached their peak values. Temperatures that were too high (100℃) or too low (25℃, 50℃) led to insufficient chain segment orientation or thermal deformation of the film, resulting in a significant decrease in performance. The nanogenerator constructed based on this series of composite films showed the best output performance for the device corresponding to the 90℃ hot-rolled composite film.

[0066] Summary of performance test results

[0067]

[0068]

[0069]

[0070]

[0071] As can be seen from the test results of the above embodiments and comparative examples, this invention achieves a significant improvement in the piezoelectric properties and cycle stability of the composite film by precisely controlling the optimal ratio of ZnO nanoparticles to CMWCNTs, combined with process optimization of hot rolling at 90℃. The synergistic control of the component ratios and process parameters is key to achieving uniform filler dispersion, increased β-phase content, and optimized chain segment orientation. The overall performance of the prepared composite film is superior to that of existing unoptimized P(VDF-TrFE)-based composite materials. The piezoelectric / triboelectric nanogenerator constructed based on this composite film fully leverages the synergistic effect of piezoelectricity and triboelectricity, significantly improving device output performance and cycle stability. It can achieve efficient harvesting of low-grade mechanical energy and has significant practical application value in fields such as self-powered systems and flexible wearable electronics.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-performance P(VDF-TrFE)-based composite membrane, characterized in that, The composite membrane is a P(VDF-TrFE) / ZnO / CMWCNTs composite membrane. Based on the mass of the P(VDF-TrFE) copolymer, the addition amount of each component is as follows: P(VDF-TrFE) copolymer: TrFE molar content is 30%; ZnO nanoparticles: mass fraction 0.36~1.80%; CMWCNTs: mass fraction of 0.01~0.03%.

2. The high-performance P(VDF-TrFE)-based composite membrane according to claim 1, characterized in that: The composite film has an orientation degree of 0.66 and a remanent polarization value of 22 μC / cm. 2 The piezoelectric coefficient is 46 pC / N, and the piezoelectric performance shows no significant decay after 10,000 cycles of testing.

3. The high-performance P(VDF-TrFE)-based composite membrane according to claim 1, characterized in that: The ZnO nanoparticles have a particle size of 30~45 nm, and the CMWCNTs conductive filler has an aspect ratio of 30~80.

4. The method for preparing the high-performance P(VDF-TrFE)-based composite membrane according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) Preparation of casting solution: P(VDF-TrFE) copolymer was dissolved in DMF solvent and stirred until completely dissolved. Then ZnO nanoparticles and CMWCNTs were added and ultrasonically dispersed to form a uniform casting solution. (2) Casting film: Casting solution is cast onto a clean glass plate, vacuum dried to remove solvent, and annealed to obtain an unrolled composite film; (3) Hot rolling treatment: The unrolled composite film is hot rolled and then naturally cooled to room temperature to obtain the high-performance P(VDF-TrFE) / ZnO / CMWCNTs composite film.

5. The method for preparing the high-performance P(VDF-TrFE)-based composite membrane according to claim 4, characterized in that, In step (1), the mass fraction of the solution prepared by dissolving the P(VDF-TrFE) copolymer in DMF solvent is 10%. Based on the mass of the P(VDF-TrFE) copolymer, the contents of ZnO nanoparticles and CMWCNTs are 1.08 wt% and 0.02 wt%, respectively. The stirring temperature is 60℃ and the ultrasonic dispersion time is 45~55 min.

6. The method for preparing the high-performance P(VDF-TrFE)-based composite membrane according to claim 4, characterized in that, In step (2), the vacuum drying temperature is 80℃ and the drying time is 20 h, the annealing temperature is 140℃ and the annealing time is 2 h.

7. The method for preparing the high-performance P(VDF-TrFE)-based composite membrane according to claim 4, characterized in that, In step (3), the hot rolling temperature is 25℃~100℃, and the hot rolling is performed 5~7 times at a linear speed of 7 mm / s.

8. A piezoelectric / triboelectric nanogenerator, characterized in that: The piezoelectric layer of the nanogenerator is a high-performance P(VDF-TrFE) based composite film as described in any one of claims 1-7.

9. The piezoelectric / triboelectric nanogenerator according to claim 8, characterized in that: Using a PET film as the positive triboelectric layer, a conductive adhesive is attached to one side of the composite film as the positive electrode, and the other side of the composite film is electrically connected to one end of the PET film through the conductive adhesive. A conductive adhesive is attached to the other side of the PET film as the negative electrode. The actual effective working area of ​​the device is 2.0 cm × 1.0 cm.

10. The piezoelectric / triboelectric nanogenerator according to claim 8, characterized in that: The generator has an open-circuit voltage of up to 31 V and a maximum power density of 15.3 μW / cm². 2 A palm strike can drive at least 200 LEDs, and the output performance shows no significant degradation after 10,000 cycles of testing.

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