Aqueous zinc-ion battery and piezoelectric response composite diaphragm thereof

Abstract

This invention belongs to the field of electrochemical energy storage device technology, specifically relating to a piezoelectrically responsive composite separator for aqueous zinc-ion batteries. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries includes a polymer fiber skeleton and a piezoelectric material dispersed in the polymer fiber skeleton. The overall piezoelectric strain constant of the piezoelectrically responsive composite separator is... d 33 The absolute value is greater than 1 pm·V −1 The piezoelectric material has a thickness of 20-60 μm, a tensile strength greater than 5 MPa, and an electrolyte absorption rate greater than 500%. Its piezoelectric properties are activated by applying an electric field during electrospinning, causing in-situ dipole orientation. Compared to existing technologies, this invention solves the technical problems of existing aqueous zinc-ion battery separators, which can only physically block or passively regulate ion flow, lacking the ability to actively control and suppress zinc dendrites, and failing to eliminate the electric field concentration caused by the tip effect, leading to uncontrolled dendrite growth and shortened battery cycle life.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device technology, specifically relating to an aqueous zinc-ion battery and its piezoelectric response composite separator, which is particularly suitable for suppressing zinc dendrite growth and improving battery cycle life. Background Technology

[0002] The separator is a key component of aqueous zinc-ion batteries, playing a crucial role in isolating the positive and negative electrodes, conducting ions, and preventing short circuits. Traditional understanding of separator design primarily focuses on physical protection and passive ion flow regulation, believing that improving the separator's mechanical strength, puncture resistance, or introducing zinc-loving functional groups and regularizing nanopores can alleviate dendrite growth. However, this view overlooks two core contradictions: First, one of the main driving forces for zinc ion migration and deposition is the electric field. During electrochemical deposition, Zn... 2+ The migration path and reduction sites of Zn are directly governed by the interfacial electric field distribution. When there are microscopic protrusions or curvature differences on the electrode surface, the electric field lines will spontaneously converge towards the high curvature region, resulting in a significantly higher local electric field intensity in that region compared to the flat region, forming a tip effect. Even if the membrane achieves homogenization of the ion flow, the non-uniformly distributed electric field will still drive Zn. 2+ First, dendrites preferentially migrate towards the tip and are reduced to deposits, continuously reinforcing morphological inhomogeneity and ultimately inducing directional dendrite growth. Second, zinc's Young's modulus (~108 GPa) is much higher than that of metallic lithium (~4 GPa). According to the Monroe-Newman theory, mechanical suppression of dendrites can be achieved when the electrolyte shear modulus is about twice that of metallic lithium. If this theory is extended to the separator system, based on the modulus of metallic zinc, the required separator modulus would need to be as high as ~200 GPa, while the Young's modulus of existing separators is only a few hundred megapascals, far from meeting this requirement. Therefore, simply relying on the physical blocking of dendrite penetration by the separator is insufficient to fundamentally solve the dendrite failure problem.

[0003] In practical applications of aqueous zinc-ion batteries, while zinc's high modulus presents a significant challenge to physical protection, it also offers unique advantages for piezoelectric control strategies. During zinc deposition, when local protrusions or initial dendrites appear on the negative electrode surface, these protrusions generate concentrated local mechanical stress on the separator. Zinc's high modulus means that the stress generated by uneven deposition is more significant, and existing separators completely lack the ability to respond to and utilize this mechanical stress, failing to convert stress signals into an effective means of controlling the electric field.

[0004] Piezoelectric response, as an important means of achieving mechanoelectric coupling control in functional materials, has shown unique advantages in the field of electrochemical energy storage. In recent years, methods for constructing separators with piezoelectric response characteristics have been reported in lithium-ion batteries; however, their application value in aqueous zinc-ion batteries has not been fully recognized, and the mechanism by which the piezoelectric response feedback-regulated electric field controls zinc deposition behavior lacks systematic research. Existing research mainly focuses on physical protection and passive ion current control, with no reports on the synergistic effect of active mechanoelectric coupling with piezoelectric response. Therefore, how to utilize the mechanoelectric coupling effect of piezoelectric response to drive uniform zinc deposition and achieve aqueous zinc-ion batteries with large area capacity, high discharge depth, high stability, and long cycle life has become a pressing technical challenge for aqueous zinc-ion batteries. Summary of the Invention

[0005] This invention aims to solve the technical problems of existing aqueous zinc-ion battery separators, which can only physically block or passively regulate ion flow, lack the ability to actively suppress zinc dendrites, and are difficult to eliminate the concentration of electric field at the tip, resulting in uncontrollable dendrite growth and short cycle life.

[0006] To solve the above problems, the technical solution of the present invention is as follows: A piezoelectrically responsive composite separator for aqueous zinc-ion batteries includes a polymer fiber skeleton and a piezoelectric material dispersed in the polymer fiber skeleton. The overall piezoelectric strain constant of the piezoelectrically responsive composite separator is... d 33 The absolute value is greater than 1 pm·V −1 The thickness is 20-60 μm, the tensile strength is greater than 5 MPa, and the liquid absorption rate in the electrolyte is greater than 500%. Its preparation method includes the following steps: The first step is to uniformly disperse the piezoelectric material in a polymer solution containing a dispersant to obtain a spinning precursor solution; The second step involves electrospinning the spinning precursor solution with the following process parameters: positive voltage of 10-25 kV, negative voltage of −3-0 kV (preferably, the positive voltage of the high-voltage electric field is 16-17 kV, and the negative voltage is −1.5 to -0.5 kV), and a receiving distance of 13cm-23cm. The electric field applied during electrospinning causes the piezoelectric material to undergo in-situ dipole orientation, thereby achieving in-situ polarization of the piezoelectric material during electrospinning, exciting the piezoelectric material's properties, and collecting the fiber membrane. The third step is to perform post-processing on the fiber membrane to obtain a piezoelectric response composite membrane.

[0007] As an improvement of the piezoelectric response composite separator for aqueous zinc-ion batteries of the present invention, the piezoelectric material is barium titanate-polyacrylonitrile, which combines the high piezoelectric activity of inorganic materials with the flexibility and easy processing of organic materials, thus achieving synergistic optimization of piezoelectric performance and applicability.

[0008] As an improvement of the piezoelectric response composite separator for aqueous zinc-ion batteries of the present invention, the dispersant is polyvinylpyrrolidone (PVP).

[0009] As an improvement of the piezoelectric response composite membrane for aqueous zinc-ion batteries of the present invention, the polymer in the polymer solution is polyacrylonitrile (PAN), and polyvinylpyrrolidone is used as a functional component to disperse and fix the ceramic filler, with a mass ratio of PAN to polymer 1:100 to 10:100.

[0010] As an improvement of the piezoelectric response composite separator for aqueous zinc-ion batteries of the present invention, the piezoelectric response composite separator has a thickness of 20-60 μm, a tensile strength greater than 8 MPa, and a liquid absorption rate in electrolyte greater than 700%.

[0011] As an improvement of the piezoelectric response composite separator for aqueous zinc-ion batteries of the present invention, the mass ratio of the piezoelectric material to the polymer in the first step is 1:100 to 30:100.

[0012] As an improvement of the piezoelectric response composite membrane for aqueous zinc-ion batteries of the present invention, the post-treatment includes at least one of drying, heat treatment, solvent replacement and crosslinking treatment.

[0013] The present invention also provides an aqueous zinc-ion battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator. The separator is the piezoelectric response composite separator described in the present invention. This separator can respond to the local mechanical stress generated by the uneven deposition on the surface of the zinc negative electrode, generate a reverse piezoelectric field, weaken the local electric field strength at the dendrite tip, guide the uniform deposition of zinc ions, and thus inhibit the growth of zinc dendrites in the aqueous zinc-ion battery.

[0014] The separator is positioned in the battery such that the direction of the piezoelectric polarization field of the separator is opposite to the direction of the external electric field applied during battery charging, so as to achieve negative feedback regulation of zinc deposition.

[0015] Preferably, the overall piezoelectric strain constant of the piezoelectric responsive composite diaphragm is... d 33 Greater than 30 pm V −1 .

[0016] Preferably, in the first step, the mass ratio of the piezoelectric material to the polymer is 10:100; and the mass ratio of polyvinylpyrrolidone to polyacrylonitrile is 2:100.

[0017] Preferably, the thickness of the piezoelectric response composite diaphragm is 30-50 μm, the tensile strength is greater than 8 MPa, and the liquid absorption rate in the electrolyte is greater than 700%.

[0018] As a further preferred technical solution, the piezoelectric responsive composite diaphragm is prepared by an electrospinning-in-situ polarization integrated method, which includes at least the following specific steps: The first step involves dissolving PAN and PVP in N,N-dimethylformamide at a mass ratio of 100:2, adding tetragonal barium titanate nanoparticles with a mass fraction of 10% PAN, ultrasonically dispersing for 1 hour, and then stirring at 60°C for 12 hours to obtain a spinning precursor solution. The second step involves electrospinning the spinning precursor solution at a feed rate of 0.06 mm / min, setting a positive voltage of 16.5 kV, a negative voltage of −1.5 kV, a receiving distance of 15 cm, a drum rotation speed of 500 rpm, and collecting the fiber membrane. The third step involves drying the collected fiber membrane in a vacuum drying oven at 80°C for 12 hours to remove residual solvent, thus obtaining a piezoelectric response composite membrane.

[0019] An aqueous zinc-ion battery includes a positive electrode, a negative electrode, an electrolyte, and a piezoelectric-responsive composite separator as described in any of the above technical solutions.

[0020] As a preferred technical solution, the negative electrode is a zinc foil; the positive electrode is zinc vanadate (Zn). x (V2O5·H2O); the electrolyte is an aqueous solution of zinc trifluoromethanesulfonate.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention effectively solves the technical problem of existing diaphragms lacking the ability to actively suppress zinc dendrites. By introducing barium titanate filler with piezoelectric response characteristics, the diaphragm can respond to the localized mechanical stress generated by zinc dendrite growth, constructing a localized adaptive piezoelectric feedback electric field in situ to weaken the tip effect. Piezoelectric microscopy (PFM) characterization shows that the piezoelectric strain constant of the obtained composite diaphragm... d 33 Reached 35.03 pm V −1 The electro-mechanical coupling effect is significant.

[0022] 2. Scanning electron microscopy (SEM) after cycling showed that the zinc anode surface of the diaphragm of the present invention was smooth, dense, and dendrite-free after cycling at different current densities.

[0023] 3. Effectively solves the technical problem of short cycle life caused by uncontrolled zinc dendrite growth. A Zn||Zn symmetric coin cell assembled using the piezoelectric composite separator (polarization direction set to negative feedback) of this invention achieves a cycle life of 1 mA cm⁻¹.−2 1 mAh cm −2 It can cycle stably for more than 2800 hours under certain conditions, with a polarization overpotential of about 30 mV; it can still cycle stably for more than 600 hours at 80% high depth of discharge.

[0024] 4. Effectively solves the technical problem of poor cycle stability of pouch batteries under high capacity and high areal capacity conditions. The Zn||Zn symmetric pouch battery (single-layer cell capacity 130.5 mAh) assembled using the separator of this invention achieves a cycle stability of 2.5 mA cm⁻¹. −2 5 mAhcm −2 Under certain conditions, it can cycle stably for over 300 hours. The 40 mAh Zn||ZVO prototype pouch battery operates at 0.2 A g. −1 After 130 cycles at current density, the capacity retention rate is as high as 94.21%, demonstrating excellent practical application potential.

[0025] 5. It possesses both excellent engineering adaptability and potential for large-scale preparation. This invention employs an integrated electrospinning-in-situ polarization method to achieve uniform composite of functional fillers and polymer fiber skeletons. The membrane thickness is only about 41 μm, the tensile strength reaches 8.14 MPa, the liquid absorption rate is moderate (~724%), and it has good flexibility and mechanical strength, and is compatible with existing battery winding and stacking processes. Attached Figure Description

[0026] Figure 1 The physical properties of the diaphragm are characterized. These include (a) thickness, (b) flexibility, (c) tensile strength, and (d) liquid absorption rate. Figure 2 The piezoelectric force microscopy (PFM) test results of the piezoelectric response composite membrane prepared in Example 1 of the present invention are shown in (a) as the amplitude / phase-voltage hysteresis curve of Comparative Example 1, (b) as the amplitude / phase-voltage hysteresis curve of Example 1, (c) as the phase distribution diagram of Example 1, and (d) as the amplitude distribution diagram of Example 1. Figure 3 The images are scanning electron microscope (SEM) images of the zinc anode surface under different diaphragm systems after 20 cycles, where (a) is Comparative Example 1, (b) is Comparative Example 2, and (c) is Example 1. Figure 4 The X-ray diffraction (XRD) curves of the zinc anode surface under different diaphragm systems after 20 cycles are shown, where (a) is Comparative Example 1 and (b) is Example 1. Figure 5 For Zn||Zn symmetric coin cells with different separators, at 1 mA cm⁻¹ −2 1 mAh cm −2 Comparison of cyclic performance under different conditions, where (a) is Comparative Example 1 and (b) is Example 1; Figure 6 The graph shows a comparison of the cycle performance of Zn||Zn symmetric cells with different separators under 80% high discharge depth conditions, where (a) is Comparative Example 1 and (b) is Example 1. Figure 7 For Zn||Zn symmetric pouch cells assembled with different separators (single-layer cell capacity 130.5 mAh), at 2.5 mA cm⁻¹ −2 5 mAh cm −2 Comparison of cyclic performance under different conditions, where (a) is Comparative Example 1 and (b) is Example 1; Figure 8 Zn||ZVO full cells with different separators at 4 A g −1 Comparison of cycling performance under current density, where (a) is Comparative Example 1 and (b) is Example 1; Figure 9 The graph shows a comparison of the cycle performance of the Zn||Zn symmetric pouch cell and the Zn||ZVO pouch full cell using Example 1, where (a) is the symmetric pouch cell (2.5 mA cm⁻¹). −2 5 mAh cm −2 (b) Soft-pack full battery (0.2 A g) −1 Cyclic performance and charge / discharge curves; Figure 10 This diagram illustrates the mechanism by which the piezoelectric composite diaphragm influences the interfacial electric field and zinc deposition behavior of the zinc anode. Detailed Implementation

[0027] To make the above-mentioned objectives, technical solutions and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] The piezoelectric-responsive composite membrane used in this invention comprises a polymer fiber skeleton and a piezoelectric material uniformly dispersed within the polymer fiber skeleton. The polymer fiber skeleton is a mixture of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP); the piezoelectric material is tetragonal barium titanate (BaTiO3). The composite membrane exhibits piezoelectric response characteristics, and its piezoelectric strain constant... d 33 Greater than 30 pmV −1 When the composite separator is assembled in an aqueous zinc-ion battery, its polarization electric field direction is set opposite to the direction of the external electric field during battery charging (negative feedback regulation) to achieve active control of zinc deposition. Its preparation method includes at least the following steps: The first step is to uniformly disperse the piezoelectric material in a polymer solution containing a dispersant to obtain a spinning precursor solution; The second step is to electrospin the spinning precursor solution and collect the fiber membrane under a high voltage electric field, so as to simultaneously achieve fiber forming and piezoelectric filler dipole orientation. The third step is to dry the collected fiber membrane to obtain a piezoelectric response composite membrane.

[0029] Specifically, the piezoelectric material is tetragonal barium titanate (BaTiO3) with an average particle size of 50 nm; the polymer is polyacrylonitrile (PAN, average molecular weight 150,000); the dispersant is polyvinylpyrrolidone (PVP, K30), with a PAN to PVP mass ratio of (40~60):1; and the solvent is N,N-dimethylformamide (DMF). The positive voltage of the high-voltage electric field is 16-17 kV, and the negative voltage is −1.5 to −0.5 kV. The mass ratio of the piezoelectric material to the polymer is 5:100 to 15:100, preferably 10:100.

[0030] This invention details one of the preparation methods: (1) Prepare chemical raw materials: polyacrylonitrile (PAN, average molecular weight 150,000), polyvinylpyrrolidone (PVP, K30), tetragonal barium titanate (BaTiO3, average particle size 50 nm), N,N-dimethylformamide (DMF, analytical grade); instruments and equipment: electronic balance, ultrasonic cleaner, magnetic stirring heating table, electrospinning machine, vacuum drying oven.

[0031] (2) Dissolve 0.2 g PVP in 10 mL DMF and stir at room temperature until completely dissolved. Add 1.0 g BaTiO3 nanoparticles and ultrasonically disperse for 1 hour to form a uniform suspension. Then add 10 g PAN powder in several portions and stir continuously in a 60°C water bath for 12 hours until PAN is completely dissolved to obtain a spinning precursor solution.

[0032] (3) Draw the precursor solution into a 20 mL syringe and attach it to the electrospinning equipment. Set the process parameters as follows: positive voltage 16.5 kV, negative voltage −1.5 kV; distance from needle tip to receiving roller 15 cm; solution advance speed 0.06 mm / min; roller speed 500 rpm. After the Taylor cone is stably formed, spin continuously for about 8 hours and collect the fiber membrane on the roller.

[0033] (4) The collected fiber membrane was placed in a vacuum drying oven at 80°C and dried for 12 hours to remove residual solvent, and a piezoelectric response composite membrane was obtained, denoted as PVB. Example

[0034] Battery assembly and electrochemical testing (1) Preparation of chemical raw materials: zinc foil (thickness 100 μm, purity >99.99%), zinc trifluoromethanesulfonate (Zn(OTf)2, 98%), zinc vanadate (Zn x V2O5·H2O, ZVO (synthesized using existing technology), conductive carbon black (Super-P), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP); Instruments and equipment: electronic balance, ultrasonic cleaner, vacuum drying oven, button battery sealing machine, blue electric test system, electrochemical workstation.

[0035] (2) Zinc negative electrode treatment: Use 500-2000 grit sandpaper to polish the commercial zinc foil in sequence to remove the surface oxide layer, then wash it with deionized water, use filter paper to absorb the surface moisture, and cut it into round pieces with a diameter of 10 mm for later use.

[0036] (3) Preparation of positive electrode: ZVO active material, conductive carbon black and PVDF are mixed in a mass ratio of 7:2:1, and an appropriate amount of NMP is added to grind into a uniform slurry. The slurry is coated onto a carbon-coated stainless steel current collector with a scraper and dried in a vacuum drying oven at 80°C for 12 hours. The slurry is then cut into round pieces with a diameter of 10 mm to obtain ZVO positive electrode sheets.

[0037] (4) Separator preparation: The PVB separator prepared in Example 1 was cut into circular pieces with a diameter of 16 mm. When assembling the battery, the polarization electric field direction of the separator was set to be opposite to the direction of the external electric field during battery charging (i.e., negative feedback regulation).

[0038] (5) Electrolyte preparation: Dissolve 2M Zn(OTf)2 in deionized water and stir until completely dissolved.

[0039] (6) Battery assembly: Assemble the CR2032 coin cells in an argon glove box. The assembly sequence is as follows: negative electrode shell, spring, gasket, zinc negative electrode, separator, electrolyte (approximately 50 μL), ZVO positive electrode, and positive electrode shell. Seal the cells under 50 MPa pressure using a sealing machine, and perform electrochemical testing after standing for 4 hours.

[0040] (7) Pouch Battery Assembly: The cut zinc negative electrode (2 pieces), ZVO positive electrode (1 piece), and PVB separator (2 pieces) are stacked in the order of "negative electrode-separator-positive electrode-separator-negative electrode", and the alignment is controlled by an automatic stacking machine. Both positive and negative electrode tabs are made of nickel, and the positive electrode tabs and negative electrode tabs are welded separately using an ultrasonic spot welder. The stacked cells are placed in an aluminum-plastic film shell, with the tabs leading out from the top. The top tab area and the two side edges are heat-sealed sequentially using a heat sealing machine, leaving one side open as the electrolyte injection port. 2M Zn(OTf)2 electrolyte (about 2 mL) is injected through the electrolyte injection port. The battery is pre-vacuumed in a vacuum sealing machine to remove residual gas inside the cell before the final heat sealing is completed. The sealed pouch battery is left to stand at room temperature for 4 hours to allow the electrolyte to fully impregnate it. During battery testing, a parallel clamping fixture is used to apply a uniform stacking pressure (about 0.1 MPa) to the pouch battery.

[0041] (8) Electrochemical testing: Constant current charge-discharge testing was performed using the Blue Electricity testing system. Symmetrical cell test conditions: Current density 1 mA cm⁻¹ −2 Surface capacity 1 mAh cm −2 Full cell test conditions: voltage range 0.3-1.6 V, current density 4 Ag. −1 .

[0042] Comparative Example 1 The battery was assembled and tested according to the method of Example 1, but a pure PAN electrospun separator (without BaTiO3 filler, and other preparation steps were the same) was used instead of a PVB separator, and other conditions were the same. This separator is referred to as PAN.

[0043] Comparative Example 2 The battery was assembled and tested according to the method of Example 1, but when using a PVB separator, the polarization electric field direction was set to be the same as the direction of the external electric field when the battery was charging (positive feedback), and other conditions were the same. This was denoted as PVB (positive feedback).

[0044] Performance test results Figure 1 To characterize the physical properties of the diaphragm, by Figure 1 It can be seen that the thickness of Example 1 is 41 μm, the tensile strength is 8.14 MPa, and the liquid absorption rate in the electrolyte is 724.19%.

[0045] piezoelectric microscopy test results ( Figure 2 The results show that Example 1 exhibits a significant piezoelectric response, with a piezoelectric strain constant. d 33 Reached 35.03 pmV −1 The first example exhibits a typical butterfly curve and phase hysteresis behavior; while the second example shows no piezoelectric response.

[0046] After 20 cycles, the surface morphology of the zinc anode under different diaphragm systems showed significant differences. Figure 3 Comparative Example 1 showed a rough and loose zinc anode surface with dendrites; Comparative Example 2 showed a loose, sheet-like deposition; while the zinc surface in Example 1 was smooth and dense, without dendrites, and induced a preferred orientation of the Zn(002) crystal plane (I). (002) / I (101) The ratio increased from 0.32 to 0.74, while Comparative Example 1 showed no such change. Figure 4 A Zn||Zn symmetric cell using the separator from Example 1 was tested at 1 mA cm⁻¹. −2 1 mAh cm −2 Under stable cycling conditions, the battery achieved over 2800 hours with a polarization overpotential of only about 30 mV; while the battery using Comparative Example 1 experienced short-circuit failure in about 15 hours. Figure 5 Under conditions of 80% high depth of discharge (DOD), Example 1 could still cycle stably for over 600 hours, while Comparative Example 1 failed after only 5 hours. Figure 6 The Zn||Zn symmetric pouch cell (single-layer cell capacity 130.5 mAh) assembled in Example 1 was used at 2.5 mA cm⁻¹. −2 5 mAh cm −2 Stable cycling for over 300 hours under certain conditions ( Figure 7 This indicates that the diaphragm of the present invention has excellent dendrite suppression ability under extreme operating conditions.

[0047] Regarding the full-cell cycle performance, the Zn||ZVO full cell of Example 1 achieved a cycle performance of 4 A g. −1 After 700 cycles at the current density, the capacity retention rate reached 94.3%, and the coulombic efficiency remained above 99.5%; while the battery using Comparative Example 1 experienced short-circuit failure after 520 cycles. Figure 8 Furthermore, the 40 mAh Zn||ZVO pouch cell from Example 1 was used at 0.2 A g. −1 After 130 cycles, the capacity retention rate reached 94.21%, and the charge-discharge curves almost overlapped; while the soft-pack battery in Comparative Example 1 failed rapidly due to a short circuit under the same conditions. Figure 9 The above results demonstrate that the piezoelectrically responsive composite separator of the present invention exhibits excellent cycle stability and practical application potential in both coin cells and pouch cells.

[0048] Example 2 Unlike Example 1, the amount of BaTiO3 filler added in step (2) is 5 wt% (based on the mass of PAN). The rest is the same as in Example 1, and will not be repeated here.

[0049] Example 3 Unlike Example 1, the amount of BaTiO3 filler added in step (2) is 15 wt%.

[0050] The rest is the same as in Example 1, and will not be repeated here.

[0051] Example 4 Unlike Example 1, in step (3), the positive voltage for electrospinning is set to 16.0 kV and the negative voltage is set to −1.0 kV. The rest is the same as in Example 1, and will not be repeated here.

[0052] Example 5 Unlike Example 1, in step (3), the positive voltage for electrospinning is set to 17.0 kV and the negative voltage is set to −1.5 kV. The rest is the same as in Example 1, and will not be repeated here.

[0053] Example 6 Unlike Example 1, the current density for the symmetrical cell test in step (8) is 5 mA cm⁻¹. −2 The surface capacity is 5mAh cm −2 .

[0054] Example 7 Unlike Example 1, in step (8), the positive electrode material of the full cell is MnO2 (commercially available γ-crystalline form), and the test current density is 1 A g. −1 .

[0055] Example 8 Unlike Example 1, in this example, polyvinylidene fluoride (PVDF) is used instead of barium titanate nanoparticles as the piezoelectric material, that is, an organic piezoelectric polymer is used as the active filler.

[0056] Example 9 Unlike Example 1, the piezoelectric material in this example uses quartz nanoparticles (α-SiO2, average particle size 100 nm) instead of barium titanate.

[0057] Example 10 Unlike Example 1, the piezoelectric material used in this example is potassium sodium niobate (K). 0.5 Na 0.5 NbO3 (KNN, average particle size 80 nm) can be used to replace barium titanate to demonstrate the advantages of lead-free and environmentally friendly products.

[0058] Example 11 Unlike Example 1, the piezoelectric material in this example uses zinc oxide nanoparticles (ZnO, average particle size 50 nm) instead of barium titanate.

[0059] The rest is the same as in Example 1, and will not be repeated here.

[0060] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A piezoelectrically responsive composite separator for aqueous zinc-ion batteries, characterized in that, The piezoelectric responsive composite membrane comprises a polymer fiber skeleton and a piezoelectric material dispersed within the polymer fiber skeleton, wherein the overall piezoelectric strain constant is... d 33 The absolute value is greater than 1 pm·V −1 The thickness is 20-60 μm, the tensile strength is greater than 5 MPa, and the liquid absorption rate in the electrolyte is greater than 500%. Its preparation method includes the following steps: The first step is to uniformly disperse the piezoelectric material in a polymer solution containing a dispersant to obtain a spinning precursor solution; The second step involves electrospinning the spinning precursor solution with the following process parameters: positive voltage of 10-25 kV, negative voltage of −3-0 kV, and receiving distance of 13-23 cm. The electric field applied during electrospinning causes the piezoelectric material to undergo in-situ dipole orientation, thereby achieving in-situ polarization of the piezoelectric material during electrospinning, exciting the piezoelectric material's properties, and collecting the fiber membrane. The third step is to perform post-processing on the fiber membrane to obtain a piezoelectric response composite membrane.

2. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 1, characterized in that, The piezoelectric material is barium titanate-polyacrylonitrile.

3. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 1, characterized in that, The dispersant is polyvinylpyrrolidone (PVP).

4. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 3, characterized in that, The polymer in the polymer solution is polyacrylonitrile (PAN), and polyvinylpyrrolidone is used as a functional component to disperse and fix the ceramic filler. The mass ratio of PAN to the polyacrylonitrile is 1:100 to 10:

100.

5. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 1, characterized in that, The piezoelectric responsive composite diaphragm has a thickness of 20-60 μm, a tensile strength greater than 8 MPa, and an electrolyte absorption rate greater than 700%.

6. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 1, characterized in that, The mass ratio of the piezoelectric material to the polymer in the first step is 1:100 to 30:

100.

7. The piezoelectrically responsive composite separator for aqueous zinc-ion batteries according to claim 1, characterized in that, The post-processing includes at least one of drying, heat treatment, solvent replacement, and crosslinking.

8. An aqueous zinc-ion battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator, characterized in that, The separator is the piezoelectric response composite separator as described in claims 1-7. This separator can respond to the local mechanical stress generated by the uneven deposition on the zinc negative electrode surface, generate a reverse piezoelectric field, weaken the local electric field strength at the dendrite tip, guide the uniform deposition of zinc ions, and thus inhibit the growth of zinc dendrites in aqueous zinc-ion batteries.

9. The battery according to claim 8, characterized in that, The separator is positioned in the battery such that the direction of the piezoelectric polarization field of the separator is opposite to the direction of the external electric field applied during battery charging, so as to achieve negative feedback regulation of zinc deposition.

10. The battery according to claim 8, characterized in that, The negative electrode is a zinc foil; the positive electrode is zinc vanadate (Zn). x (V2O5·H2O); the electrolyte is an aqueous solution of zinc trifluoromethanesulfonate.

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