Hydrophilic zinc ion battery diaphragm as well as preparation method and application thereof

Abstract

The invention belongs to the field of batteries, and relates to a battery diaphragm, in particular to a hydrophilic zinc ion battery diaphragm as well as a preparation method and application thereof. The preparation method comprises the following steps: immersing absorbent cotton into a NaOH solution, and carrying out water bath pretreatment to obtain cellulose; immersing cellulose into a H2O2 solution, and carrying out oil bath modification treatment to obtain modified cellulose; drying the modified cellulose, adding deionized water, uniformly mixing, and carrying out suction filtration to obtain a primary cellulose membrane; and drying and pressing the primary cellulose membrane to obtain the hydrophilic zinc ion battery diaphragm. The hydrophilic diaphragm enables the aqueous zinc ion battery to show excellent electrochemical performance in a symmetric battery and a total battery through rich hydrophilic groups and excellent mechanical performance; the preparation of the hydrophilic diaphragm is based on the low-cost absorbent cotton material, the simple and convenient preparation method is adopted, and the hydrophilic diaphragm has good practical application prospects and large-scale production potential.

Description

Technical Field

[0001] The present invention belongs to the field of batteries and relates to battery separators. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) have received extensive attention due to their environmental friendliness, cost-effectiveness, and high safety. However, due to the accumulation of water molecules at the electrode-electrolyte interface, serious side reactions are usually triggered. The deposition and desolvation of hydrated zinc ions at the zinc negative electrode-electrolyte interface can lead to a locally high concentration of water molecules, inevitably triggering serious parasitic reactions, uneven zinc deposition, and the formation of zinc dendrites. In addition, the accumulation of water molecules at the positive electrode-electrolyte interface may cause the dissolution of the positive electrode material during repeated charge and discharge processes, which is mainly attributed to the invasion of water molecules at the lattice defects of the positive electrode material, reducing the stability of the chemical bonds of the positive electrode material, thus significantly limiting the cycling performance and rate performance of AZIBs. Therefore, it is crucial to suppress side reactions by regulating interfacial water molecules for achieving excellent zinc storage performance.

[0003] As a key component of zinc-ion batteries, the separator not only plays a role in separating the positive and negative electrodes to prevent short circuits, but also maintains close contact with the electrode materials and provides rich migration channels for electrolyte ions. Therefore, separator modification is an effective means to solve the aggregation of interfacial water molecules, which leads to side reactions. The patent with publication number CN 115064835 A discloses a separator for aqueous zinc-ion batteries and its preparation method, which prepares a composite separator based on meltblown nonwoven and suction filtration technologies. However, the current preparation process of modified separators is relatively complex, greatly reducing the practical application prospects of modified separators. Developing a separator with a simple preparation process, excellent mechanical properties, and the ability to effectively regulate interfacial water molecules is of great significance for improving the electrochemical performance of aqueous zinc-ion batteries. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a hydrophilic zinc-ion battery separator and its preparation method and application.

[0005] The technical solution of the present invention is realized as follows: On the one hand, the present application provides a preparation method of a hydrophilic zinc-ion battery separator (HP separator), and the steps are as follows: (1) Pretreat cotton wool with a NaOH solution; (2) Chemically modify the pretreated cellulose, and dry the modified cellulose by freeze-drying; (3) Add the dried cellulose into deionized water, stir and then perform suction filtration to obtain a primary cellulose membrane; (4) The primary cellulose membrane is placed in an oven for drying, and a tablet press is used to press the dried cellulose membrane flat.

[0006] In the above step (1), the concentration of the NaOH solution is 1 - 3 M; the temperature of the water bath pretreatment is 80 °C and the time is 6 - 8 h; the specific operation is as follows: The degreased cotton is immersed in the NaOH solution with a concentration of 1 - 3 M, and water bath treatment is carried out for 6 - 8 h, and the temperature is controlled at 80 °C. Subsequently, it is washed with deionized water to remove the residual NaOH.

[0007] In the above step (2), the volume concentration of the H2O2 solution is 10% - 20%; the temperature of the oil bath modification treatment is 110 °C and the time is 6 - 8 h; the specific operation is as follows: The cellulose washed in step (1) is immersed in the H2O2 solution with a concentration of 10%, and oil bath treatment is carried out for 8 hours, and the temperature is controlled at 110 °C. Subsequently, it is washed with deionized water again to remove the residual H2O2. Then the obtained modified cellulose is dried by freeze-drying for 12 h to obtain a dried modified cellulose material.

[0008] In the above step (3), the mass ratio of the modified cellulose to deionized water is 1:250 - 1000; the drying is freeze-drying and the time is 8 - 12 h; the specific operation is as follows: 0.1 g of the modified cellulose material dried in step (2) is added to 50 ml of deionized water, stirred for 3 hours and then filtered by suction to obtain a preliminary cellulose membrane, which is placed in an oven at 50 °C for drying for 8 h for treatment.

[0009] In the above step (4), the drying temperature is 50 - 70 °C and the time is 8 - 12 h; the pressing pressure is 5 - 10 MPa; the cellulose membrane dried in step (3) is pressed flat by a tablet press with a pressure of 5 - 10 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0010] In the second aspect, the present application provides a highly hydrophilic zinc-ion battery separator. The highly hydrophilic zinc-ion battery separator, the HP separator, prepared through the above steps has relatively uniform and large fiber diameters, which is beneficial to achieving excellent mechanical properties. The fiber diameter of 30 - 50 μm of the separator enhances the magnitude of its mechanical properties, thus affecting the application and performance of the aqueous zinc-ion battery.

[0011] In the third aspect, the present application also requests protection for the application of the above highly hydrophilic zinc-ion battery separator.

[0012] In the fourth aspect, it requests protection for the battery prepared by using the above highly hydrophilic zinc-ion battery separator. The battery can be a full battery or a symmetric battery.

[0013] The present invention has the following beneficial effects: 1. The present invention provides a method for preparing a separator for a zinc-ion battery with high hydrophilicity. The obtained HP separator has a fiber diameter of 30 - 50 μm. The HP separator obtained by the preparation method provided by the present invention has good mechanical properties, realizing its application as a separator for zinc-ion batteries.

[0014] 2. The hydrophilic separator prepared by the present invention, as a separator for zinc-ion batteries, anchors interfacial water molecules on the hydrophilic separator through hydrogen bonding between hydroxyl groups and water molecules, thereby reducing the enrichment of interfacial water molecules, and the long-cycle performance of the battery is more excellent; the hydroxyl groups are beneficial to promoting the desolvation process of hydrated zinc ions and accelerating the zinc-ion migration kinetics, thereby reducing the zinc-ion concentration difference on the negative electrode surface and forming a uniform interfacial electric field, specifically manifested as inhibiting the growth of dendrites.

[0015] 3. The hydrophilic separator enables the aqueous zinc-ion battery to stably cycle for 2000 h in a symmetric battery and 5000 cycles in a full battery through its rich hydrophilic groups and excellent mechanical properties; the preparation of the hydrophilic separator in this application is based on low-cost cotton materials and uses a simple preparation method, having good practical application prospects and the potential for large-scale production; through density functional theory (DFT) calculations, COMSOL simulations, in-situ optical microscopy, in-situ XRD, and AFM studies, the present invention deeply reveals the optimization mechanism of the hydrophilic separator on electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the preparation process of the present invention.

[0018] Figure 2 It is an SEM image of the hydrophilic separator of the present invention.

[0019] Figure 3 It is an XRD pattern of the hydrophilic separator of the present invention.

[0020] Figure 4 It is an FTIR spectrum of the hydrophilic separator of the present invention.

[0021] Figure 5 It is a stress-strain curve of the hydrophilic separator of the present invention.

[0022] Figure 6 It is a puncture test curve of the hydrophilic separator of the present invention.

[0023] Figure 7 Hydrophilicity test of the hydrophilic separator of the present invention.

[0024] Figure 8 DFT calculation of the hydrophilic separator of the present invention.

[0025] Figure 9 COMSOL surface electric field simulation of the hydrophilic separator of the present invention.

[0026] Figure 10 COMSOL surface zinc ion concentration simulation of the hydrophilic separator of the present invention.

[0027] Figure 11 In-situ XRD pattern of the hydrophilic separator of the present invention.

[0028] Figure 12 AFM image of the hydrophilic separator of the present invention.

[0029] Figure 13 Cycling performance of the symmetric cell assembled with the hydrophilic separator of the present invention at a current density of 10 mA cm -2 Current density.

[0030] Figure 14 Rate performance of the full cell assembled with the hydrophilic separator of the present invention at a current density of 200 mA g -1 - 10 A g -1 Current density.

[0031] Figure 15 Cycling curve of the full cell assembled with the hydrophilic separator of the present invention according to the embodiment of the present invention at a current density of 20 A g -1 Current density for 5000 cycles. Detailed implementation mode

[0032] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Unless otherwise specified, the test methods used in the following experimental examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained from commercial channels.

[0034] Example 1 A preparation method of a hydrophilic zinc ion battery separator (HP separator) in this example, and the preparation process is as Figure 1 shown, and the steps are as follows: 1) Immerse absorbent cotton in a NaOH solution with a concentration of 2 M, and perform a water bath treatment for 6 hours at a temperature controlled at 80 °C. Subsequently, wash with deionized water to remove residual NaOH; 2) Immerse the cellulose washed in step 1) in a H2O2 solution with a concentration of 10%, and perform an oil bath treatment for 8 hours at a temperature controlled at 110 °C. Subsequently, wash again with deionized water to remove residual H2O2; then dry the modified cellulose by freeze-drying for 12 h to obtain a dried modified cellulose material.

[0035] 3) Take 0.1 g of the modified cellulose material dried in step 2) and add it to 50 ml of deionized water. Stir for 3 hours and then perform suction filtration to obtain a preliminary cellulose membrane, and place it in an oven at 50 °C to dry for 8 h for treatment.

[0036] 4) Press the cellulose membrane dried in step 3) flat with a tablet press at a pressure of 5 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0037] The SEM image of the HP separator prepared in this example is as Figure 2 shown. It can be seen from Figure 2 that the HP separator has a fiber diameter of 30 - 50 μm. The fiber diameter of the separator directly restricts its mechanical properties, thereby affecting the application and performance of aqueous zinc-ion batteries. The XRD image is as Figure 3 shown. It can be seen from Figure 3 that the HP separator shows diffraction peaks at 14.7°, 16.3°, 22.5° and 34.1°, corresponding to the (101), (10 ), (002) and (040) crystal planes of cellulose I; the FTIR image is as Figure 4 shown. It can be seen from Figure 4 that the diffraction peaks of the HP separator at 3350 and 2896 cm −1 can correspond to the O-H and C-O stretching vibrations in cellulose molecules. This indicates that the HP separator contains abundant hydroxyl groups. The presence of hydroxyl groups is beneficial to improving the ionic conductivity and ionic migration rate of zinc-ion batteries, reducing the internal resistance of the battery, and improving the charge-discharge efficiency of the battery.

[0038] Perform mechanical property tests on the HP separator prepared in Example 1. The test steps are as follows: Experimental process of stress-strain test: (1) Specimen preparation: Prepare specimens with standard dimensions according to experimental requirements and material types. (2) Install experimental equipment: Fix the specimen in the clamping device of the equipment to ensure that the specimen is centered and has no initial stress. (3) Apply load: Slowly apply tensile, compressive or bending loads to cause uniform deformation of the specimen. (4) Measure stress and strain: Use an extensometer to measure the strain of the specimen in real time. (5) Record data: Record the load-displacement curve or stress-strain curve. (6) Analyze results: Draw the stress-strain curve and evaluate the deformation characteristics of the diaphragm.

[0039] Experimental process of needle-punching test: (1) Specimen preparation: Ensure that the thickness, dimensions and surface quality of the specimen are uniform. (2) Select the needle: Select a suitable needle shape and size according to experimental requirements. (3) Fix the specimen: Fix the specimen on the experimental table to ensure that it does not move or deform during the needle-punching process. (4) Apply needle-punching load: Use a needle-punching testing machine or a manual device to vertically insert the needle into the specimen. (5) Record data: Record the load (force) applied during the needle-punching process and the displacement of the needle. (6) Analyze results: Calculate the puncture resistance strength, toughness and other properties of the material based on the load-displacement curve.

[0040] The test results are as Figure 5 、 Figure 6 shown. It can be seen from this figure that the tensile stress of the HP diaphragm reaches 2.5 MPa, while the tensile stress of the GF diaphragm is only 0.1 Mpa. The puncture strength of the HP diaphragm is 7.4 times that of the GF diaphragm. This data indicates that the HP diaphragm performs better in resisting external mechanical impacts and internal zinc dendrite punctures. These results show that the HP diaphragm has excellent mechanical properties.

[0041] The hydrophilicity of the HP diaphragm prepared in Example 1 was tested. The test steps are as follows: (1) Experimental preparation: Ensure that the contact angle measuring instrument is in normal working condition. Check whether the camera, light source, measurement software, etc. of the equipment are running normally. (2) Environmental control: Control the experimental environment under constant temperature and humidity conditions to avoid the influence of temperature and humidity changes on the liquid surface tension and solid surface properties. (3) Fix the specimen: Use a fixture or other fixing device to fix the solid sample on the test bench of the contact angle measuring instrument to ensure that the sample does not move during the test. (4) Drop the liquid: Use a micro syringe or other precise liquid transfer tool to drop the standard liquid onto the surface of the sample. The dropping amount is usually controlled at a few microliters to ensure that the droplet shape is regular. (5) Take a picture of the droplet morphology: After the liquid is dropped, immediately use the high-precision camera and light source of the contact angle measuring instrument to take a picture of the droplet morphology. Ensure that the light is uniform and avoid shadows or reflections. (6) Analyze results: Use the contact angle measurement software to analyze the droplet morphology, automatically identify the droplet edge and calculate the size of the contact angle.

[0042] The test results are as follows Figure 7 shown. It can be seen from this figure that the electrolyte infiltrates the HP separator in only 0.24 s, indicating that the HP separator has excellent hydrophilic properties.

[0043] DFT calculations were performed on the prepared HP separator, as Figure 8 shown. By optimizing the adsorption configuration of water molecules on HP, the adsorption energies of CHOH- and CH2OH- groups in the HP separator for water molecules were calculated to be -0.489 eV and -0.681 eV, respectively, which are significantly higher than the adsorption energies of Si- (-0.441 eV) and SiO- (-0.293 eV) groups in the GF separator. This result indicates that the HP separator has a stronger ability to capture water molecules, thereby effectively suppressing the activity of water molecules at the positive and negative electrode interfaces, as shown in Figure 8 the figure.

[0044] COMSOL simulations were performed on the prepared HP separator, as Figure 9 , Figure 10 shown. The COMSOL simulation revealed the optimization mechanism of the HP separator for zinc deposition behavior. As Figure 9 shown, a uniform electric field distribution was observed using the HP separator compared to the GP separator, as Figure 10 shown, which helps to achieve a uniform zinc ion flux pattern and is beneficial for suppressing the formation of zinc dendrites when using the HP separator. In addition, the average concentration of zinc ions on the zinc negative electrode using the HP separator is significantly higher than that using the GF separator, which is beneficial for improving the kinetic performance.

[0045] Example 2 A preparation method of a hydrophilic zinc ion battery separator (HP separator) in this example, the preparation process is as Figure 1 shown, and the steps are as follows: 1) Immerse the absorbent cotton in a 1 M NaOH solution, and perform a water bath treatment for 8 hours at a temperature controlled at 80 °C. Subsequently, wash with deionized water to remove the NaOH residue; 2) Immerse the cellulose washed in step 1) in a 10% (v / v) H2O2 solution, and perform an oil bath treatment for 8 hours at a temperature controlled at 110 °C. Subsequently, wash again with deionized water to remove the H2O2 residue; then dry the modified cellulose by freeze-drying for 8 h to obtain a dried modified cellulose material.

[0046] 3) Take 0.05 g of the dried modified cellulose material obtained in step 2) and add it to 50 ml of deionized water. Stir for 3 hours and then perform suction filtration to obtain a preliminary cellulose membrane, which is placed in an oven at 50 °C and dried for 12 h for treatment.

[0047] 4) Press the cellulose membrane dried in step 3) flat using a tablet press at a pressure of 5 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0048] Example 3 A method for preparing a hydrophilic zinc-ion battery separator (HP separator) in this example has a preparation process as Figure 1 shown below, and the steps are as follows: 1) Immerse absorbent cotton in a 3 M NaOH solution and perform a water bath treatment for 8 hours at a temperature controlled at 80 °C. Subsequently, wash with deionized water to remove residual NaOH; 2) Immerse the cellulose washed in step 1) in a 10% (v / v) H2O2 solution and perform an oil bath treatment for 8 hours at a temperature controlled at 110 °C. Subsequently, wash again with deionized water to remove residual H2O2; then dry the modified cellulose by freeze-drying for 8 h to obtain a dried modified cellulose material.

[0049] 3) Take 0.1 g of the modified cellulose material dried in step 2) and add it to 50 ml of deionized water. Stir for 3 hours and then perform suction filtration to obtain a preliminary cellulose membrane, which is placed in an oven at 60 °C and dried for 8 h for treatment.

[0050] 4) Press the cellulose membrane dried in step 3) flat using a tablet press at a pressure of 8 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0051] Example 4 A method for preparing a hydrophilic zinc-ion battery separator (HP separator) in this example has a preparation process as Figure 1 shown below, and the steps are as follows: 1) Immerse absorbent cotton in a 2 M NaOH solution and perform a water bath treatment for 6 hours at a temperature controlled at 80 °C. Subsequently, wash with deionized water to remove residual NaOH; 2) Immerse the cellulose washed in step 1) in a 20% (v / v) H2O2 solution and perform an oil bath treatment for 8 hours at a temperature controlled at 110 °C. Subsequently, wash again with deionized water to remove residual H2O2; then dry the modified cellulose by freeze-drying for 12 h to obtain a dried modified cellulose material.

[0052] 3) Take 0.2 g of the modified cellulose material dried in step 2) and add it to 50 ml of deionized water. Stir for 3 hours and then perform suction filtration to obtain a preliminary cellulose membrane, which is placed in an oven at 70 °C and dried for 12 h for treatment.

[0053] 4) Press the cellulose membrane dried in step 3) flat using a tablet press at a pressure of 10 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0054] Example 5 A preparation method of a hydrophilic zinc-ion battery separator (HP separator) in this example has a preparation process as Figure 1 shown, and the steps are as follows: 1) Immerse absorbent cotton in a 3 M NaOH solution and perform water bath treatment for 8 hours at a temperature controlled at 80 °C. Subsequently, wash with deionized water to remove residual NaOH; 2) Immerse the cellulose washed clean in step 1) in a 20% H2O2 solution and perform oil bath treatment for 6 hours at a temperature controlled at 110 °C. Subsequently, wash again with deionized water to remove residual H2O2; then dry the modified cellulose by freeze-drying for 8 h to obtain a dried modified cellulose material.

[0055] 3) Take 0.2 g of the modified cellulose material dried in step 2) and add it to 50 ml of deionized water. Stir for 3 hours and then perform suction filtration to obtain a preliminary cellulose membrane, which is placed in an oven at 50 °C and dried for 12 h for treatment.

[0056] 4) Press the cellulose membrane dried in step 3) flat using a tablet press at a pressure of 10 MPa to obtain an HP separator with excellent mechanical properties and hydrophilicity.

[0057] Application Example 1 Assemble the HP separator prepared in Example 1 into a symmetric battery, and the operation is as follows: Cut zinc sheets as the positive and negative electrodes. The thickness of the zinc sheets used is ~100 μm, and they are cut into zinc circular sheets with an area of 1 cm -2 Test under the condition of 10 mA cm -2 , and the test results are as Figure 13 shown. It can be seen from Figure 13 that the symmetric battery has high stability and can stably cycle for 2000 h at a current density of 10 mAcm -2 .

[0058] After the cycle, verify the effect of the HP separator on inhibiting dendrite growth through AFM technology, as Figure 12 shown. It can be seen from the AFM diagram that the zinc negative electrode is flatter after cycling with the HP separator, indicating that the generation of zinc negative electrode dendrites is inhibited.

[0059] Application Example 2 The HP separator prepared in Example 1 was assembled into a full cell as follows: Ammonium vanadate was used as the positive electrode active material in the battery, and the loading of the positive electrode sheet was 1.2 - 1.5 mg cm −2 . After the positive electrode sheet was prepared, a zinc sheet was cut as the negative electrode. The thickness of the zinc sheet used was ~100 μm, and it was cut into a zinc disc with an area of 2 cm -2 . A CR2016 button battery case was used to assemble the battery. The zinc disc and the separator were placed on the negative electrode case in sequence. Then, 200 μL of electrolyte was added to the separator using a pipette. After waiting for the separator to be completely wetted, the positive electrode sheet was put in. Finally, the positive electrode case was covered and pressed using a tablet press. The assembled full cell could be subjected to electrochemical tests after standing at room temperature for 6 h, and tests were carried out under different rate conditions.

[0060] The test results are as Figure 14 shown. When the current density gradually increased from 0.2 A g -1 to 10 A g -1 , the full cell assembled with the HP separator exhibited excellent rate performance. At current densities of 0.2 A g -1 , 0.5 A g -1 , 1 A g -1 , 3 A g -1 , 5 Ag -1 and 10 A g -1 , high reversible specific capacities of 526.8 mAh g -1 , 514.4 mAh g -1 , 501.4 mAh g -1 , 432.4 mAh g -1 , 336.2 mAh g -1 and 193.6 mAh g -1 were shown respectively, indicating that the full cell assembled with the HP separator had a high reversible capacity, and the HP separator could improve the kinetic performance of the full cell.

[0061] The stability of the above full cell was detected, and a cycling experiment was carried out at a current density of 20 A g -1 . The results are as Figure 15 shown. As Figure 15 can be seen, after cycling 2000 times at a current density of 20 A g -1 , the capacity retention rate was 93.97%; after cycling 3000 times at a current density of 20A g -1 , the capacity retention rate was 90.52%; after cycling 4000 times at a current density of 20 A g -1 , the capacity retention rate was 86.21 %; 20 A g-1 After 5000 cycles at a current density of

[0062] Meanwhile, in-situ XRD technology was used to monitor the cathode material during the charge and discharge process of the battery. The results are as Figure 11 shown. After using the HP separator, the by-product Zn4(OH)6SO4·xH2O (ZHS) formed in the cathode material, where x represents the amount of crystal water, decreased significantly. The hydroxyl functional groups of the HP separator can interact with water molecules in the electrolyte, reducing the content of free water at the interface. This effect inhibits the side reaction between the cathode material and water molecules, thereby reducing the formation of ZHS. During the charge and discharge process, the characteristic peak of ZHS appears first and then disappears, indicating that the redox reaction of the cathode material has higher reversibility. This means that the energy loss of the battery is smaller and the cycle efficiency is higher during the charge and discharge process. The HP separator significantly inhibits the occurrence of side reactions and reduces the formation of by-products by regulating the water molecule content at the electrode interface, thereby improving the cycle stability and reversibility of the battery.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a hydrophilic zinc ion battery separator, characterized in that, The steps are as follows: (1) Immerse absorbent cotton in the NaOH solution and conduct a water bath pretreatment to obtain cellulose; (2) Immerse the cellulose obtained in step (1) in the H2O2 solution and conduct an oil bath modification treatment to obtain modified cellulose; (3) After drying the modified cellulose in step (2), add deionized water, mix well, and then conduct suction filtration to prepare a primary cellulose membrane; (4) Dry and press the primary cellulose membrane in step (3) to obtain a hydrophilic zinc-ion battery separator.

2. The preparation method of the hydrophilic zinc ion battery separator according to claim 1, characterized in that: In step (1), the concentration of the NaOH solution is 1 - 3 M; the temperature of the water bath pretreatment is 80 °C and the time is 6 - 8 h.

3. The preparation method of the hydrophilic zinc-ion battery separator according to claim 2, characterized in that: In step (2), the volume concentration of the H2O2 solution is 10% - 20%; the temperature of the oil bath modification treatment is 110 °C and the time is 6 - 8 h.

4. The preparation method of the hydrophilic zinc ion battery separator according to claim 3, characterized in that: In step (3), the mass ratio of the modified cellulose to deionized water is 1:250 - 1000; the drying is freeze-drying and the time is 8 - 12 h.

5. The preparation method of the hydrophilic zinc ion battery separator according to claim 4, characterized in that: In step (4), the temperature of the drying is 50 - 70 °C and the time is 8 - 12 h; the pressure of the pressing is 5 - 10 MPa.

6. The preparation method of the hydrophilic zinc ion battery separator according to any one of claims 1-5, characterized in that: After the water bath pretreatment in step (1) and the oil bath modification treatment in step (2), both need to be washed with deionized water.

7. A hydrophilic zinc-ion battery separator prepared by the method according to claim 6.

8. The application of the hydrophilic zinc-ion battery separator according to claim 7 in the preparation of a high-performance battery.

9. A battery, characterized in that: Containing the hydrophilic zinc-ion battery separator according to claim 7.

10. The battery according to claim 9, characterized in that: The battery is a symmetric battery or a full battery.

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