Hydrophobic zinc-ion battery separator based on inorganic oxide and its use in zinc batteries

Abstract

The application discloses a kind of hydrophobic zinc ion battery separators based on inorganic oxide and its application in zinc battery, belong to secondary zinc battery field.Hydrophobic separator is composed of inorganic oxide and binder.Preparation method is that inorganic oxide (Ta2O5, Al2O3 or La2O3 etc.) and binder (PVDF) mass ratio is (8~10):1 stirring makes it mix evenly;Slurry is placed on glass plate, and it is coated evenly using doctor blade;Drying;Using deionized water makes separator and glass plate separate, and prepared hydrophobic separator.The separator has hydrophobicity, can isolate a large amount of free water, while the surface contains porous structure, electrolyte ions can be freely transmitted, and the hydrophilic glass fiber separator self-assembled "hydrophobic-hydrophilic-hydrophobic" separator is used for long-life zinc ion battery, and the hydrophilic separator can store a large amount of electrolyte, guarantee zinc battery high-performance cycle, and the hydrophobic separator can isolate a large amount of free water to prevent electrode corrosion or dissolution.

Description

Technical Field

[0001] This invention belongs to the field of novel battery energy storage, and in particular relates to a hydrophobic zinc-ion battery separator based on inorganic oxides and its application in zinc batteries. Background Technology

[0002] The inherent safety issues of lithium-ion batteries have led to numerous fires and explosions in electrochemical energy storage power stations, severely hindering the industry's development. Aqueous zinc-ion batteries are considered one of the strongest contenders for next-generation low-cost energy storage devices. Their rapid development is attributed to their high safety, fast charge / discharge capabilities, and high energy density. However, the practical application of zinc-ion batteries is limited by several issues: short circuits caused by rampant dendrite growth penetrating the separator; severe hydrogen evolution and corrosion side reactions that shorten the battery's cycle life; and capacity degradation due to cathode dissolution. These problems are primarily determined by the electrode / electrolyte and electrolyte / separator interfaces.

[0003] Currently, researchers have explored various strategies and methods to improve the lifespan of zinc batteries by enhancing the stability of the electrode / electrolyte interface. However, they have neglected the interfacial interaction between the electrolyte and the separator. Traditional hydrophilic separators, such as glass fiber and filter paper, cannot prevent direct contact between the electrolyte and the electrode, leading to severe corrosion of the zinc anode surface and hydrogen evolution side reactions. This also causes the cathode to dissolve, resulting in a rapid decline in battery life. Conversely, hydrophobic separators cannot transport the electrolyte through water, causing poor cycle performance due to insufficient electrolyte. Therefore, to completely solve the interfacial problem between the battery electrode and separator, it is essential to study the combination of hydrophilic and hydrophobic separators to effectively avoid contact with large amounts of free water while simultaneously transporting the electrolyte through bound water. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a hydrophobic zinc-ion battery separator based on inorganic oxides and its application in zinc batteries. When the hydrophobic separator of this application is used to assemble a hydrophobic-hydrophilic-hydrophobic separator in a zinc battery, it can isolate a large amount of free water and allow a small amount of bound water to transport the electrolyte, providing more zinc ion transport channels and improving the cycle life of the zinc battery.

[0005] To solve the technical problem of this invention, the technical solution adopted is as follows: A hydrophobic zinc-ion battery separator based on inorganic oxides is obtained through the following process: 1) The inorganic oxide and the binder are dissolved in an appropriate amount of NMP at a mass ratio of (8~10):1 and stirred for 5~15 hours to make them evenly mixed; the inorganic oxide is at least one of Ta2O5, Al2O3 and La2O3 or a mixture of two or more in any proportion, and the binder is PVDF; 2) Place the slurry on a glass plate, use a scraper to coat it evenly and let it dry; 3) Use deionized water to separate the separator from the glass plate to obtain a hydrophobic zinc-ion battery separator.

[0006] Furthermore, the drying process involves placing the coated glass plate in a drying oven or vacuum oven at a drying temperature of 30-50°C. The "hydrophobic-hydrophilic-hydrophobic" separator is a structure formed by the self-assembly of hydrophobic and hydrophilic separators during the battery assembly process for use in zinc batteries.

[0007] Furthermore, the hydrophobicity of the separator is relative to that of the hydrophilic glass fiber separator, which can isolate a large amount of free water; the thickness of the hydrophobic zinc-ion battery separator is 10-20 micrometers, and the surface has a nanoscale porous structure.

[0008] The porous structure consists of nanoscale pores distributed across the membrane surface. The membrane porous structure allows electrolytes to be transported through a small amount of bound water, while a large amount of free water cannot pass through.

[0009] Furthermore, the hydrophobic zinc-ion battery separator is used in zinc batteries.

[0010] Furthermore, zinc sheet is used as the negative electrode, vanadium dioxide or zinc sheet is used as the positive electrode, and hydrophobic zinc-ion battery separator, glass fiber and hydrophobic zinc-ion battery separator are assembled into a hydrophobic-hydrophilic-hydrophobic separator structure as the battery separator, and 0.5~2 mol / L zinc sulfate solution is used as the electrolyte to assemble a zinc battery.

[0011] Furthermore, the zinc battery is a zinc-vanadium dioxide full cell, a zinc-zinc symmetric cell, or a zinc-vanadium dioxide pouch full cell.

[0012] Furthermore, the structure of a zinc-zinc symmetric battery is: positive electrode shell, zinc sheet, hydrophobic separator, hydrophilic separator, hydrophobic separator, zinc sheet, gasket, negative electrode shell; the structure of a zinc-vanadium dioxide full battery is: positive electrode shell, stainless steel mesh, vanadium dioxide positive electrode, hydrophobic separator, hydrophilic separator, hydrophobic separator, zinc sheet, gasket, negative electrode shell; the structure of a zinc-vanadium dioxide pouch full battery is: zinc sheet, hydrophobic separator, hydrophilic separator, hydrophobic separator, vanadium dioxide positive electrode.

[0013] In the aforementioned zinc battery, the stainless steel mesh is 400 mesh, and the gasket thickness is 500μm.

[0014] The preparation process of vanadium dioxide cathode is as follows: VO2 powder and carbon black powder are dry-milled for 5-15 minutes, then an appropriate amount of isopropanol and 55-65 wt% PTFE aqueous solution are added, and wet milling continues until a paste is formed; the mixture is rolled into thin sheets using a roller press, with isopropanol continuously added during rolling to maintain the viscosity of the PTFE; the long sheets are sliced ​​using a slicing machine, dried, and the resulting cathode sheet has a VO2 loading of 5.4-6.2 mg / cm³. -2 The mass ratio of VO2 powder, carbon black and PTFE is 6:2:2.

[0015] The advantages over existing technologies are: Firstly, it improves the interface between the electrodes and the separator, significantly extending battery life. A hydrophobic separator prepared from inorganic oxides is used to assemble a "hydrophobic-hydrophilic-hydrophobic" separator for zinc-ion batteries, achieving high current densities of 5 mA cm⁻¹. -2 10mA cm -2 Under the test conditions, compared to the untreated zinc anode, the battery cycle life significantly exceeded that of the battery using only a hydrophilic glass fiber separator, with an average improvement of more than 15 times. The assembled full cell exhibited high specific capacity and excellent cycle performance, retaining 60.4% of its capacity after 1000 cycles at 2C. The assembled pouch cell, after 40 cycles at 0.5C, showed a cycle time exceeding 240 hours and a capacity of 172.5 mAh g / g. -1 High specific capacity. Compared with other patents, this technology uses a higher current density and has a lifespan far exceeding that of other patented methods.

[0016] Secondly, the "hydrophobic-hydrophilic-hydrophobic" structure membrane is functionalized. Hydrophobic membranes can be prepared by mixing inorganic oxides (Ta2O5, Al2O3, or La2O3, etc.) and binders (PVDF), forming a surface nanoporous structure. This membrane, combined with a hydrophilic glass fiber membrane, self-assembles into a "hydrophobic-hydrophilic-hydrophobic" membrane for use in zinc batteries. The hydrophobic layer membrane is only 10 micrometers thick, much thinner than thick glass fibers; it functions to transport electrolytes, block large amounts of free water, and regulate Zn content. 2+ The ability to deposit electrolytes uniformly. The hydrophilic glass fiber membrane in the middle functions to store electrolytes and ensure their free transport back and forth.

[0017] Thirdly, the preparation method is simple and effective, and can be widely applied on a large scale. First, inorganic oxides (such as Ta₂O₅, Al₂O₃, or La₂O₃) and binders (PVDF) are mixed at a mass ratio of 9:1 until homogeneous. Then, the slurry is placed on a glass plate, coated evenly using a 120-micron coater, and dried. Finally, deionized water is used to separate the membrane from the glass plate, and the membrane is dried to obtain a hydrophobic separator. This preparation method is simple, allows for the mass production of hydrophobic separators, and enables the formation of a "hydrophobic-hydrophilic-hydrophobic" structure for use in zinc-ion batteries, providing a new approach for the engineering application of aqueous battery separators. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a method for preparing hydrophobic membranes based on inorganic oxides; Figure 2 These are SEM images of the surface morphology of the hydrophobic separator and a schematic diagram of the application of the "hydrophobic-hydrophilic-hydrophobic" separator in zinc battery assembly. Figure 3 These are images showing the dynamic contact angles between the surfaces of the glass fiber diaphragm and the hydrophobic diaphragm. Figure 4 These are the XRD patterns of the zinc electrode and the inorganic oxide (Ta2O5); Figure 5 SEM images of zinc surface morphology after cycling of zinc batteries in Comparative Example 2 and Example 1; Figure 6 These are ion permeation experiments with different diaphragms and graphs showing the ion concentrations of the permeate. Figure 7 The graphs show the long-cycle test curves of zinc-zinc symmetric batteries in Comparative Example 2 and Example 1. Figure 8 This is a comparison of the long-cycle test results of zinc-zinc symmetric batteries with different separators under different test conditions; Figure 9 The cycling curves of zinc vanadium dioxide full cells for Comparative Example 3 and Example 2 are shown. Figure 10 This is a cycle curve graph of the soft-pack full battery of Comparative Example 4 and Example 3. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and examples.

[0020] Comparative Example 1 Preparation and structural characterization of hydrophobic membranes.

[0021] Step 1, Preparation of hydrophobic membrane First, inorganic oxides (such as Ta2O5, Al2O3, or La2O3) and binder (PVDF) are dissolved in an appropriate amount of NMP at a mass ratio of 9:1 and stirred for 8 hours to ensure uniform mixing. Approximately 1.5 mL of NMP is required for every 100 mg of solids (inorganic oxide + PVDF). Then, the slurry is placed on a glass plate and coated evenly with a 120-micron doctor blade and dried in a vacuum oven at 40°C. Finally, deionized water is used to separate the membrane from the glass plate and dried at 40°C to obtain a hydrophobic membrane with a thickness of 10 μm to 20 μm.

[0022] Step 2, Characterization of hydrophobic membrane structure The hydrophobicity of the membrane was verified using dynamic contact angle, such as... Figure 3 As shown. When 1 mol·L -1 When ZnSO4 electrolyte droplets are dropped onto the glass fiber membrane, the contact angle is 0°, indicating its superhydrophilicity. The membrane prepared by this technique has a contact angle of 85.82° at 10 s, indicating its hydrophobicity. However, as time progresses, the contact angle gradually decreases to 73.15° at 60 s. This can fully explain why the hydrophobic membrane can isolate a large amount of free water and only allow electrolyte transport through a small amount of bound water. The XRD results of Ta2O5 are as follows... Figure 4 The results show that the peaks of the inorganic oxide (Ta2O5) highly match the peaks of the zinc (002) crystal plane, which can guide the uniform deposition of zinc ions. (SEM image follows) Figure 2 The results show that the hydrophobic membrane consists of a porous structure with a homogeneous mixture of PVDF and inorganic oxide (Ta2O5), which is beneficial for zinc ion transport.

[0023] Comparative Example 2 Zinc-zinc symmetric batteries were assembled using hydrophilic glass fiber separators.

[0024] Step 1, Zinc electrode preparation A 200μm thick pure zinc foil (purchased from Sinopharm Chemical Reagents) was ultrasonically cleaned with ethanol (ultrasonic frequency 40kHz, power 300W, time 5 minutes). The zinc foil was then cut into pieces with a diameter of 12mm and an area of ​​approximately 1.13cm² using an electrode slicer. 2 The discs were cleaned again with ethanol using ultrasonic cleaning (ultrasonic frequency 40kHz, power 300W, time 5 minutes), and then dried in a vacuum oven at 40℃ for 1 hour.

[0025] Step 2, Zinc-symmetric cell assembly Zinc electrodes were assembled into symmetrical CR2016 model cells (20.0 mm in diameter and 1.6 mm in thickness) for cycle stability testing. The cell components, in sequence, consisted of a positive electrode shell, a pure zinc sheet, a glass fiber separator, another pure zinc sheet, a stainless steel gasket (16 mm in diameter and 500 μm in thickness), and a negative electrode shell. The sealing pressure was approximately 50 kg / cm³. The cells needed to stand at room temperature for at least 2 hours before use. The separator was made of glass fiber (manufactured by Whatman, 110 mm in diameter and 260 μm in thickness, cut into 19 mm diameter discs). The electrolyte used was a 1 mol / L (or 1 M) zinc sulfate solution, with 100 μL added to each cell immediately after the separator was placed in place. The 1 M zinc sulfate electrolyte was prepared by dissolving ZnSO₄∙7H₂O (analytical grade, purchased from Sinopharm Chemical Reagent) in pure water at a mass ratio of approximately 11.5024:34.9556.

[0026] Step 3, Zinc Symmetric Cell Testing The long-cycle testing of the symmetrical batteries was conducted in a constant-temperature chamber maintained at 25°C to eliminate the influence of ambient temperature. The battery testing used was a battery testing system from Wuhan Landian. Figure 7 As shown, the test parameters were set to constant current discharge and constant current charge, with a current density of 5 mA / cm² based on the electrode area. 2 The surface area capacity is 1mAh / cm². 2 Under these test conditions, the symmetrical cell lifespan using a hydrophilic glass fiber separator is approximately 120 hours, indicating a shorter cell lifespan. Furthermore, at higher test current densities, such as... Figure 8 As shown, at 10mA / cm 2 1mAh / cm 2 Under these conditions, the lifespan of the symmetrical cell is 163 hours.

[0027] Step 4: Observation of dendrites on the surface of zinc symmetric cells The surface morphology of the zinc electrode after 120 hours of death was observed using a Zeiss focused dual-ion beam scanning electron microscope (SEM). Figure 5 As shown, after long-term zinc deposition and stripping, the electrode surface is covered with disordered and irregular dendrites, which is the main cause of battery short circuits.

[0028] Comparative Example 3 Assemble zinc-vanadium dioxide full cells using hydrophilic glass fiber membranes Step 1, Zinc electrode preparation.

[0029] Same as Comparative Example 2, Step 1.

[0030] Step 2, Preparation of vanadium dioxide cathode VO2 powder was purchased from a Taobao manufacturer. The VO2 positive electrode sheet was prepared using a current collector-free rolling method to increase the loading of the active material. The VO2 positive electrode sheet consisted of VO2 powder, carbon black, and PTFE in a mass ratio of 6:2:2. First, 150 mg of VO2 powder and 50 mg of carbon black powder were dry-milled for 10 minutes. Then, an appropriate amount of isopropanol and 83.3 mg of a 60wt% PTFE aqueous solution (PTFE mass was 50 mg) were added, and wet milling continued in a fume hood until a paste was formed. Next, the mixture was rolled into thin sheets using a roller press. Isopropanol was continuously added during rolling to maintain the PTFE's viscosity. The long sheets were sliced ​​using a slicer under controlled humidity. They were then cut into circular slices with a diameter of 11 mm (approximately 0.949 cm²). 2 Then, it was dried in an oven at 80℃ for 12 hours and weighed for later use. The VO2 loading of the active material in the positive electrode is approximately 6.2 mg / cm³. -2 .

[0031] Step 3, Full Battery Assembly The zinc and VO2 electrodes were assembled into a CR2016 model full cell (20.0 mm in diameter and 1.6 mm in thickness). The assembly sequence was as follows: positive electrode shell, stainless steel mesh (400 mesh, 12 mm in diameter), positive electrode plate, glass fiber separator, negative electrode plate, stainless steel gasket (500 μm thick), and negative electrode shell. The sealing pressure was approximately 50 kg / cm³. The battery needed to stand at room temperature for 2 hours before use. The separator was made of glass fiber (manufactured by Whatman, 110 mm in diameter, cut into 19 mm round pieces). The electrolyte used was a 1 mol / L (or 1 M) zinc sulfate solution, with 100 μL added to each cell immediately after the separator was placed in place.

[0032] Step 4, Zinc-vanadium dioxide full cell test Full-cell testing was conducted in a constant-temperature chamber (25℃) to eliminate the influence of ambient temperature. Battery testing utilized a battery testing system from Wuhan Landian. Charge-discharge tests were performed under 2C rate conditions, such as... Figure 9 As shown, the initial discharge specific capacity is 125 mAhg. -1 It then showed a downward trend, with the capacity dropping to 35mAh g after approximately 1000 cycles. -1 .

[0033] Comparative Example 4 Preparation and use of zinc electrodes in the assembly of soft-pack full cells with hydrophilic glass fiber separators.

[0034] Step 1, Preparation of the soft-pack zinc electrode A 200μm thick pure zinc sheet (purchased from Sinopharm Chemical Reagent) was ultrasonically cleaned with ethanol (ultrasonic frequency 40kHz, power 300W, time 5 minutes). The zinc sheet was then cut into 4cm×4cm zinc sheets and ultrasonically cleaned again with ethanol (ultrasonic frequency 40kHz, power 300W, time 5 minutes). Finally, it was placed in a 40℃ vacuum oven and dried for 1 hour.

[0035] Step 2, Preparation of vanadium dioxide cathode VO2 powder was purchased from a Taobao manufacturer. The VO2 cathode sheet was prepared using a non-current collector rolling method to increase the loading of active material. The VO2 cathode sheet consisted of VO2 powder, carbon black, and PTFE in a mass ratio of 6:2:2. First, 150 mg of VO2 powder and 50 mg of carbon black powder were dry-milled for 10 minutes. Then, an appropriate amount of isopropanol and 83.3 mg of 60wt% PTFE aqueous solution (PTFE mass was 50 mg) were added, and wet milling continued in a fume hood until a paste was formed. Next, the mixture was rolled into thin sheets using a roller press. Isopropanol was continuously added during rolling to maintain the viscosity of the PTFE. The mixture was cut into 4cm × 4cm cathode sheets under certain humidity conditions, then dried in an oven at 80℃ for 12 hours and weighed for later use. The VO2 loading of the active material in the cathode sheet was approximately 151.2 mg.

[0036] Step 3, Assembly of zinc vanadium dioxide pouch cells A 4cm × 4cm pouch cell was assembled with a zinc electrode and a vanadium dioxide cathode for cycle stability testing. The cells needed to be allowed to stand at room temperature for 2 hours before use. The separator was made of glass fiber (manufactured by Whatman, cut to 4.2cm × 4.2cm). The electrolyte used was a 1mol / L (or 1M) zinc sulfate solution, with 1mL added to each cell just before sealing.

[0037] Step 4, Zinc-vanadium dioxide pouch cell full cell test The pouch cell full-cell testing was conducted in a constant temperature chamber (25℃) to eliminate the influence of ambient temperature. Battery testing used a battery testing system from Wuhan Landian. Charge-discharge tests were performed at a 0.5C rate. Figure 10 As shown, the initial discharge specific capacity is 250 mAh g. -1 The capacity dropped to 40mAh in the 40th cycle. -1 .

[0038] Example 1 Hydrophobic membranes are used to form a "hydrophobic-hydrophilic-hydrophobic" structure for zinc-zinc symmetric batteries.

[0039] Step 1, Preparation of hydrophobic membrane Same as step 1 in Comparative Example 1.

[0040] Step 2, Zinc electrode preparation Same as step 1 in Comparative Example 2.

[0041] Step 3: Assemble a zinc-zinc symmetric battery using a "hydrophobic-hydrophilic-hydrophobic" structured membrane. Zinc electrodes were assembled into symmetrical CR2016 model cells (20.0 mm in diameter and 1.6 mm in thickness) for cycle stability testing. The cell components, in sequence, consisted of a positive electrode shell, a pure zinc sheet, a hydrophobic separator, a glass fiber separator, another hydrophobic separator, a zinc sheet, a stainless steel gasket (16 mm in diameter and 500 μm in thickness), and a negative electrode shell. The sealing pressure was approximately 50 kg / cm³. The cells needed to stand at room temperature for at least 2 hours before use. The glass fiber separator was made of glass fiber (manufactured by Whatman, 110 mm in diameter and 260 μm thick, cut into 19 mm diameter discs). The electrolyte used was a 1 mol / L (or 1 M) zinc sulfate solution, with 100 μL added to each cell immediately after the glass fiber separator was placed in place. The 1M zinc sulfate electrolyte is prepared by dissolving ZnSO4∙7H2O (analytical grade, purchased from Sinopharm Chemical Reagent) in pure water, with a mass ratio of approximately 11.5024: 34.9556.

[0042] like Figure 1 As shown, a glass fiber membrane, a prepared hydrophobic membrane, and a glass fiber membrane were assembled into a "hydrophobic-hydrophilic-hydrophobic" structure membrane. Using the glass fiber membrane as a control, the two membranes were tested using an ion permeation apparatus. The results are as follows. Figure 6 As shown, the "hydrophobic-hydrophilic-hydrophobic" structure membrane allows ZnSO4 electrolyte to permeate while preventing a large amount of free water from passing through. In contrast, the hydrophilic glass fiber membrane cannot prevent a large amount of free water, resulting in a decrease in the ion concentration of the permeate.

[0043] Step 4: Assembly and testing of zinc-zinc symmetric cells with a "hydrophobic-hydrophilic-hydrophobic" membrane structure. Cyclic testing was performed on the zinc-zinc symmetric battery assembled with the hydrophobic-hydrophilic-hydrophobic separator obtained in step 3. The tests were conducted in a 25°C constant temperature chamber. The battery testing system from Wuhan Landian was used. Figure 7 As shown, tests were conducted at a current density of 5 mA cm⁻¹. -2 Area and capacity 1mAh cm -2 It can cycle effectively for 2183 hours under the specified conditions; at a current density of 10 mA cm⁻¹ -2 Area and capacity 1mAh cm -2 Under certain conditions, it can be effectively cycled for more than 1800 hours.

[0044] Step 5: Compare the test results with the zinc symmetric cells in the comparative example. A zinc-zinc symmetrical cell assembled with a hydrophobic-hydrophilic-hydrophobic membrane structure at 5 mA cm⁻¹ -2 1mA h cm -2 and 10mA cm -2 1mA h cm -2 Test results under test conditions are as follows Figure 8 The battery lifespans reached over 2183 hours and 1800 hours respectively, far exceeding that of the pure zinc comparison. This fully demonstrates that the "hydrophobic-hydrophilic-hydrophobic" structured separator can significantly improve battery performance and greatly enhance cycle life.

[0045] Step 6: Use SEM to observe the surface morphology of the zinc electrode after long-term cycling. After cycle testing, the zinc electrode surface morphology of the zinc-zinc symmetric battery assembled with a hydrophobic-hydrophilic-hydrophobic membrane structure is as follows: Figure 5 As shown, the zinc surface exhibits a dense deposition without obvious dendrites. Compared to using a hydrophilic glass fiber membrane, the zinc deposition is significantly smoother and more orderly, demonstrating that the introduction of a hydrophobic membrane can achieve dense zinc deposition.

[0046] Step 7, elucidating the mechanism of the "hydrophobic-hydrophilic-hydrophobic" structured membrane in zinc-ion batteries. Figure 5 This is a schematic diagram of zinc deposition on the surface. Because the hydrophobic membrane has a porous structure, it increases the zinc ion transport channels. The inorganic oxide (Ta2O5) crystal plane in the membrane is highly matched with the zinc (002) crystal plane. Figure 4 This induces zinc ions to deposit uniformly on the surface; since the hydrophilic glass fiber membrane can store a large amount of electrolyte, and the hydrophobic membrane can block a large amount of free water, the direct contact between the electrode and water is avoided, thereby reducing hydrogen evolution and corrosion side reactions.

[0047] Example 2 Hydrophobic membranes are used to form a "hydrophobic-hydrophilic-hydrophobic" structure for zinc vanadium dioxide full cells.

[0048] Step 1, Preparation of hydrophobic membrane Same as step 1 in Comparative Example 1.

[0049] Step 2, Zinc electrode preparation Same as step 1 in Comparative Example 2.

[0050] Step 3, Preparation of vanadium dioxide cathode Same as step 2 of Comparative Example 3.

[0051] Step 4: Assemble the zinc vanadium dioxide full cell using a "hydrophobic-hydrophilic-hydrophobic" structured membrane.

[0052] Zinc electrodes were assembled into CR2016 model full cells (20.0 mm in diameter and 1.6 mm in thickness) for cycle stability testing. The battery components, in sequence, are: positive electrode shell, vanadium dioxide positive electrode sheet, hydrophobic separator, glass fiber separator, hydrophobic separator, zinc sheet, stainless steel gasket (16 mm in diameter and 500 μm in thickness), and negative electrode shell. The sealing pressure is approximately 50 kg / cm³. The batteries need to be allowed to stand at room temperature for at least 2 hours before use. The glass fiber separator is made of glass fiber (manufactured by Whatman, 110 mm in diameter, cut into 19 mm diameter discs). The electrolyte used is a 1 mol / L (or 1 M) zinc sulfate solution, with 100 μL added to each battery immediately after the glass fiber separator is placed in place. The preparation method for 1M zinc sulfate electrolyte is to dissolve ZnSO4∙7H2O (analytical grade, purchased from Sinopharm Chemical Reagent) in pure water, with a mass ratio of approximately 11.5024:34.9556.

[0053] Step 5: Assembly and testing of zinc-vanadium dioxide full cells using a "hydrophobic-hydrophilic-hydrophobic" membrane structure. Cyclic testing was conducted on the zinc-vanadium dioxide battery assembled with the hydrophobic-hydrophilic-hydrophobic separator obtained in step 4. The tests were performed in a 25°C constant temperature chamber using a battery testing system from Wuhan Landian. The battery demonstrated that it could effectively cycle 1000 times under a 2C charge-discharge rate while maintaining a capacity of 90.7 mAh g⁻¹. -1 .

[0054] Step 6: Compare the performance of zinc-vanadium dioxide full cells assembled with glass fiber membranes as a control example. A comparative analysis was conducted on the performance of a full cell assembled using a "hydrophobic-hydrophilic-hydrophobic" membrane structure with zinc as the negative electrode and vanadium dioxide as the positive electrode, and a full cell assembled using only a hydrophilic glass fiber membrane with zinc as the negative electrode and vanadium dioxide as the positive electrode. The results are as follows: Figure 9 In contrast, under 2C charge / discharge rate conditions, after 1000 cycles, the full battery using only the glass fiber separator experienced a capacity decay of 35 mAh g. -1 The initial discharge specific capacity of the full battery using a "hydrophobic-hydrophilic-hydrophobic" membrane structure is 200 mAh g. -1 It then remained stable, and after 1000 cycles, the battery discharge specific capacity still remained at 90.70 mAh g. -1 This indicates that a hydrophobic-hydrophilic-hydrophobic membrane structure can significantly improve the cycle life of the full cell.

[0055] Example 3 Zinc vanadium dioxide pouch cells assembled with a hydrophobic-hydrophilic-hydrophobic membrane structure.

[0056] Step 1, Preparation of hydrophobic membrane Same as step 1 in Comparative Example 1.

[0057] Step 2, Preparation of the soft-pack zinc electrode Same as step 1 in Comparative Example 4.

[0058] Step 3, Preparation of the soft-pack vanadium dioxide cathode Same as step 2 of Comparative Example 4.

[0059] Step 4: Assemble zinc-vanadium dioxide pouch cells using a "hydrophobic-hydrophilic-hydrophobic" structured separator. Zinc electrodes and vanadium dioxide cathodes were assembled into 4cm × 4cm pouch cells for cycle stability testing. The cells needed to be allowed to stand at room temperature for 2 hours before use. The hydrophilic glass fiber separator was made of glass fiber (manufactured by Whatman, cut to 4.2cm × 4.2cm), and the hydrophobic separator was a separator prepared using this technology, cut to 4.2cm × 4.2cm. The electrolyte used was a 1mol / L (or 1M) zinc sulfate solution, with 1mL added to each cell just before sealing.

[0060] Step 5: Assembly of zinc vanadium dioxide pouch cells with a "hydrophobic-hydrophilic-hydrophobic" membrane structure. Cyclic testing was conducted on the zinc-vanadium dioxide pouch battery assembled with the hydrophobic-hydrophilic-hydrophobic separator obtained in step 4. The tests were performed in a 25°C constant temperature chamber using a battery testing system from Wuhan Landian. After 40 cycles at a charge / discharge rate of 0.5C, the capacity remained at 172.5 mAh g / g. -1 .

[0061] Step 6: Compare the performance of zinc vanadium dioxide pouch cells assembled using glass fiber membranes with those of the control group. A pouch cell assembled using a hydrophobic-hydrophilic-hydrophobic membrane structure, with zinc as the negative electrode and vanadium dioxide as the positive electrode, was compared with a pouch cell using only a hydrophilic glass fiber membrane, with zinc as the negative electrode and vanadium dioxide as the positive electrode. The results are as follows: Figure 10 In contrast, when tested at a charge / discharge rate of 0.5C, the full battery using only the glass fiber separator showed a capacity decay of 25 mAh g after 40 cycles. -1 The initial discharge specific capacity of the full battery using a "hydrophobic-hydrophilic-hydrophobic" membrane structure is 250 mAh g. -1 It then remained stable, and after 40 cycles, the battery's discharge specific capacity remained at 172.5 mAh g. -1 This indicates that the hydrophobic-hydrophilic-hydrophobic membrane structure can be applied on a large scale in zinc batteries.

[0062] Example 4 Hydrophobic membranes are prepared using oxides (Al2O3 or La2O3) to form a "hydrophobic-hydrophilic-hydrophobic" structure membrane for use in zinc-zinc symmetric batteries.

[0063] Step 1, Preparation of hydrophobic membrane Same as step 1 in Comparative Example 1.

[0064] Step 2, Zinc electrode preparation Same as step 1 in Comparative Example 2.

[0065] Step 3: Assemble a zinc-zinc symmetric battery using a "hydrophobic-hydrophilic-hydrophobic" structured membrane. Zinc electrodes were assembled into symmetrical CR2016 model cells (20.0 mm in diameter and 1.6 mm in thickness) for cycle stability testing. The cell components, in sequence, consisted of a positive electrode shell, a pure zinc sheet, a hydrophobic separator, a glass fiber separator, another hydrophobic separator, a zinc sheet, a stainless steel gasket (16 mm in diameter and 500 μm in thickness), and a negative electrode shell. The sealing pressure was approximately 50 kg / cm³. The cells needed to stand at room temperature for at least 2 hours before use. The glass fiber separator was made of glass fiber (manufactured by Whatman, 110 mm in diameter and 260 μm thick, cut into 19 mm diameter discs). The electrolyte used was a 1 mol / L (or 1 M) zinc sulfate solution, with 100 μL added to each cell immediately after the glass fiber separator was placed in place. The 1M zinc sulfate electrolyte is prepared by dissolving ZnSO4∙7H2O (analytical grade, purchased from Sinopharm Chemical Reagent) in pure water, with a mass ratio of approximately 11.5024: 34.9556.

[0066] like Figure 1 As shown, a glass fiber membrane, a prepared hydrophobic membrane, and a glass fiber membrane are assembled into a "hydrophobic-hydrophilic-hydrophobic" structure membrane, with the glass fiber membrane used as a comparison.

[0067] Step 4: Assembly and testing of zinc-zinc symmetric cells with a "hydrophobic-hydrophilic-hydrophobic" membrane structure. Cyclic testing was conducted on the zinc-zinc symmetric battery assembled with the hydrophobic-hydrophilic-hydrophobic separator obtained in step 3. The tests were performed in a 25°C constant temperature chamber. The battery testing system from Wuhan Landian was used.

[0068] Step 5: Compare the test results with the zinc symmetric cells in the comparative example. Hydrophobic membranes were prepared using oxides (Al2O3) to form a "hydrophobic-hydrophilic-hydrophobic" structure. Zinc-zinc symmetric batteries were then assembled at 5 mA cm⁻¹. -2 1mA h cm -2 Test results under test conditions are as follows Figure 8The battery life reaches over 1500 hours, far exceeding that of the pure zinc comparative. A zinc-zinc symmetric battery was assembled using a hydrophobic membrane prepared with an oxide (La₂O₃) to form a "hydrophobic-hydrophilic-hydrophobic" structure, achieving a 5 mA cm⁻¹ test. -2 1mA h cm -2 Test results under test conditions are as follows Figure 8 The battery life reaches over 600 hours, far exceeding that of the pure zinc comparison. This fully demonstrates that the "hydrophobic-hydrophilic-hydrophobic" structure of the separator can significantly improve battery performance and greatly enhance cycle life.

[0069] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification shall also be included within the scope of protection of the present invention.

Claims

1. The application of a hydrophobic zinc-ion battery separator based on inorganic oxides in zinc batteries, characterized in that, The hydrophobic zinc-ion battery separator is obtained through the following process: 1) The inorganic oxide and the binder are dissolved in an appropriate amount of NMP at a mass ratio of (8~10):1 and stirred for 5~15 hours to make them evenly mixed; the inorganic oxide is one or more of Ta2O5, Al2O3 and La2O3 in any proportion, and the binder is PVDF; 2) Place the slurry on a glass plate, use a scraper to coat it evenly and let it dry; 3) Deionized water is used to separate the separator from the glass plate to obtain a hydrophobic zinc-ion battery separator; the thickness of the hydrophobic zinc-ion battery separator is 10~20 micrometers and the surface has a nanoscale porous structure. Zinc sheet is used as the negative electrode, vanadium dioxide or zinc sheet is used as the positive electrode, and a hydrophobic zinc-ion battery separator, glass fiber and hydrophobic zinc-ion battery separator are assembled into a hydrophobic-hydrophilic-hydrophobic separator structure as the battery separator. 0.5~2 mol / L zinc sulfate solution is used as the electrolyte to assemble a zinc battery.

2. The application according to claim 1, characterized in that, The drying process involves placing the glass plate in a drying oven or vacuum oven at a temperature of 30-50°C.

3. The application according to claim 1, characterized in that, Zinc batteries can be zinc-vanadium dioxide full cells, zinc-zinc symmetrical cells, or zinc-vanadium dioxide pouch full cells.

4. The application according to claim 3, characterized in that, The structure of a zinc-zinc symmetric battery is: positive electrode shell, zinc sheet, hydrophobic zinc-ion battery separator, glass fiber, hydrophobic zinc-ion battery separator, zinc sheet, gasket, and negative electrode shell; the structure of a zinc-vanadium dioxide full battery is: positive electrode shell, stainless steel mesh, vanadium dioxide positive electrode, hydrophobic zinc-ion battery separator, glass fiber, hydrophobic zinc-ion battery separator, zinc sheet, gasket, and negative electrode shell; the structure of a zinc-vanadium dioxide pouch full battery is: zinc sheet, hydrophobic zinc-ion battery separator, glass fiber, hydrophobic zinc-ion battery separator, and vanadium dioxide positive electrode.

5. The application according to claim 1, characterized in that, The preparation process of vanadium dioxide cathode is as follows: VO2 powder and carbon black powder are dry-milled for 5-15 minutes, then an appropriate amount of isopropanol and (55-65) wt% PTFE aqueous solution are added, and wet milling continues until a paste is formed; the mixture is rolled into thin sheets using a roller press, with isopropanol continuously added during rolling to maintain the viscosity of the PTFE; the long sheets are sliced ​​using a slicing machine, dried, and the VO2 loading in the cathode sheet is obtained as 5.4-6.2 mg / cm³. -2 The mass ratio of VO2 powder, carbon black and PTFE is 6:2:

2.

6. The application according to claim 4, characterized in that, The stainless steel mesh is 400 mesh, and the gasket thickness is 500μm.

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