One-dimensional / two-dimensional composite ion-conducting membrane, preparation method and application thereof

Abstract

The application discloses a one-dimensional / two-dimensional composite structure ion-conducting membrane and a preparation method and application thereof. The one-dimensional / two-dimensional composite structure ion-conducting membrane comprises the following components: carboxylic acid cellulose and vermiculite nanosheet. The composite structure ion-conducting membrane has a peak at 6.0+ / -0.3 degrees in an XRD spectrum. The one-dimensional structure of the carboxylic acid cellulose can realize the regulation of the membrane layer spacing in the two-dimensional material system, the regulation of the state of the water between the membrane layers, and the improvement of the mechanical properties of the membrane. The application has a good application prospect in the field of zinc batteries, can inhibit the side reaction of the battery, reduce the dendrite puncture, and has stable and reversible Zn stripping and deposition.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional materials, and more specifically, relates to a one-dimensional / two-dimensional composite structure ion-conducting membrane, its preparation method, and its application. Background Technology

[0002] Water, as a polar material, is widely considered an important and / or even indispensable solvent in various application fields due to its excellent ion dissociation ability, extremely high safety, and low cost, including rechargeable batteries, flow batteries, ion separation, and biological treatment. As a transport medium, water, as an important and / or even indispensable solvent, is used in energy storage, membrane separation, chemical reactions, and metabolic cycles.

[0003] In particular, in the field of aqueous rechargeable batteries, aqueous electrolytes (which use water instead of their organic counterparts) not only endow batteries with promising electrochemical performance due to their rapid kinetics, but also offer ease of processing, eco-friendliness, and significantly higher safety compared to organic electrolytes. Specifically, aqueous electrolytes are considered an ideal alternative to organic solvents in electrochemical rechargeable batteries due to their rapid ion migration, ease of processing, economic / environmental friendliness, and flame retardancy. These exceptional advantages have driven fundamental research and industrial applications of aqueous rechargeable batteries as large-scale storage devices for renewable energy sources such as wind and solar power. Thanks to these advantages, aqueous electrolyte-based rechargeable batteries have become ideal large-scale energy storage devices for peak shaving in wind / solar power generation.

[0004] Zinc metal is relatively stable in water, but still faces challenges under electrochemical conditions. In rechargeable batteries, aqueous electrolyte zinc batteries have attracted considerable attention due to the comparable stability and low cost of the anode material. However, the development of zinc batteries is severely hampered by several challenges, such as dendrite formation, hydrogen evolution, and byproducts. In particular, the active water in the aqueous electrolyte can lead to side reactions, metal corrosion, and uneven Zn deposition at the zinc anode. 2+ Migration and severe desorption of the cathode active material [eScience 2022, 2, 110-115.], resulting in poor Zn content. 2+ Peeling / plating behavior, poor coulombic efficiency, and early battery failure.

[0005] Therefore, suppressing the activity of water molecules in aqueous rechargeable batteries is a necessary strategy to achieve high reversible ion transport and extend battery life for practical applications. To extend battery life in practical applications, an alternative strategy is urgently needed to maintain high ion migration while reducing the activity of water.

[0006] To date, significant efforts have been made to modulate water activity in aqueous electrolytes by reducing free water content or altering the solvation structure of the electrolyte. Recently, researchers have discovered that water reactivity can be suppressed by reducing water content or controlling hydration. For example, researchers have used concentrated or molten electrolytes to reduce the percentage of free water molecules and confine water within a solvation shell of metal ions. Immediately, many research groups have utilized concentrated aqueous solutions or molten salts as electrolytes to reduce the weight ratio of water. Alternatively, ligands are added to confine water by enhancing hydrogen bonding [Nat. Mater. 2020,19, 1006-1011], thereby reducing the reactivity between water and the electrode. Alternatively, ligands or additives are used to form strong hydrogen bonds with water molecules, thereby reducing the likelihood of reaction between water and the electrode. However, these strategies impair the rapid ion kinetics of the electrochemical reaction and have limited rate performance, although battery performance has been optimized to some extent. The aforementioned methods reduce ion mobility, thus limiting battery performance. However, the state and kinetics of water have been rarely systematically studied. Meanwhile, due to limited understanding of the state of water, the optimization of ionic electrolytes mainly depends on performance evaluation.

[0007] Therefore, it is necessary to finely tune and interpret the activity of water molecules to balance kinetics (ionic conductivity and rate performance) and side reactions (battery lifetime) to achieve practical battery applications. Thus, further characterization of the water state will alone contribute to the development of solid electrolytes.

[0008] Two-dimensional (2D) laminated membranes possess nanoscale or sub-nanometer-scale channels, which have been reported to exhibit unique ballistic transport properties, exceptionally fast ion transport, and the ability to alter the state of water within a two-dimensional confined space. In recent years, two-dimensional (2D) layered structures, such as graphene oxide, vermiculite, LDH, and BiOCl, have attracted significant attention in the design of solid electrolytes due to their ultrafast ion transport within sub-nanometer 2D capillaries.

[0009] In particular, water in confined spaces exhibits different hydrodynamics compared to free water [J. Phys. Chem. C2021, 125, 16864-16874], which we believe can be utilized to control the activity of water molecules. Furthermore, confined water in 2D capillaries exhibits anomalous aggregation states [Nature 2020, 588, 250-253.] due to ultra-high vdW pressure [Nat. Commun. 2016, 7, 12168.]. Therefore, the 2D material family offers opportunities to modulate the migration and reactivity of confined water.

[0010] Therefore, in this work, utilizing the unique properties of 2D laminates, we designed pressurized water embedded between 2D laminates to achieve rapid cation transport and limited water activity. In this work, we designed a 1D / 2D structure based on vermiculite and carbon nanofiber composites, where vermiculite provides the 2D capillary structure, and nanocellulose is used to modulate the interlayer spacing by adjusting the constraints. Zn was investigated. 2+ The transport of carbon nanofibers depends on the proportion of carbon nanofibers in the 1D / 2D layered structure. The performance of the 1D / 2D composite material as a solid electrolyte was further evaluated by comparison with commercial glass fibers, and failure analysis of anodic corrosion and mechanical damage was provided. It shows promising application prospects in zinc batteries, as it can suppress side reactions, reduce dendrite penetration, and exhibit stable and reversible Zn exfoliation and deposition. Summary of the Invention

[0011] 1. The problem to be solved

[0012] To address the problem of dendrite puncture in existing membranes, this invention provides a one-dimensional / two-dimensional composite structure ion-conducting membrane.

[0013] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: This invention discloses a one-dimensional / two-dimensional composite structure ion-conducting membrane. The one-dimensional structure, within a two-dimensional material system, allows for the control of the interlayer spacing and the state of water between the membrane layers, thereby enhancing the membrane's mechanical properties. It shows promising application prospects in the field of zinc batteries, suppressing side reactions, reducing dendrite penetration, and exhibiting stable and reversible Zn exfoliation and deposition.

[0014] The first aspect of this invention provides a one-dimensional / two-dimensional composite ion-conducting membrane, comprising the following components: Carboxylic acid cellulose; and Vermiculite nanosheets; The XRD pattern of the composite ion-conducting membrane shows a peak at 6.0 ± 0.3°. This peak indicates that the membrane contains vermiculite nanosheets separated by carboxylic acid cellulose layers.

[0015] Preferably, the composite structure ion-conducting membrane contains at least one sandwich structure formed by a first vermiculite nanosheet layer, a carboxylic acid cellulose layer, and a second vermiculite nanosheet layer in sequence.

[0016] Preferably, the composite structure ion-conducting membrane contains vermiculite nanosheets with an interlayer spacing of 1.40 ~ 1.57 nm, which is calculated by XRD.

[0017] Preferably, the peak area ratio at 7.0±0.3° to 6.0±0.3° in the XRD pattern of the composite structure ion-conducting membrane is less than 20%.

[0018] Preferably, the XRD pattern of the composite structure ion-conducting membrane has no peak at 7.0±0.3°.

[0019] Preferably, the thickness of the composite structure ion-conducting membrane is 10~60μm, and more preferably 35~45μm.

[0020] Preferably, the mass ratio of carboxylic acid cellulose to vermiculite nanosheets in the composite ion-conducting membrane is (0.1~0.8):1, more preferably (0.5~0.75):1.

[0021] A second aspect of the present invention provides a method for preparing a one-dimensional / two-dimensional composite ion-conducting membrane according to any embodiment of the first aspect of the present invention, comprising the following steps: Provides a mixed dispersion containing carboxylic acid cellulose and vermiculite nanosheets; The composite structure ion-conducting membrane was obtained by filtration on the substrate.

[0022] Specifically, the method for preparing a one-dimensional / two-dimensional composite structure ion-conducting membrane includes the following steps: Step 1.1 Preparation of one-dimensional nanocellulose dispersion: Weigh a certain amount of carboxylic acid cellulose and add it to deionized water. Stir mechanically at 500-1000 rpm for 1-2 hours at 15-30℃ to obtain a transparent and colorless dispersion.

[0023] Step 1.2 Preparation of two-dimensional material vermiculite nanosheet dispersion: Vermiculite nanosheets were exfoliated from expanded vermiculite using an ion exchange method. 1-2 g of expanded vermiculite was added to a saturated NaCl solution (26.47 wt%, 200 mL) and stirred under reflux at 110-130°C for 48 hours to replace interlayer Mg²⁺ cations with Na⁺. The vermiculite slurry was centrifuged at 8000-10000 rpm and repeatedly washed with 2-3 L of deionized water to remove residual salts. The received sodium-intercalated vermiculite (NaV) was dispersed in a saturated LiCl aqueous solution (7.8 wt%, 200 mL); the resulting mixture was maintained at 110-130°C for 24 hours under continuous magnetic stirring to further replace interlayer Na⁺ with Li⁺ cations, and then cooled to room temperature. After washing with excess deionized water (2-3 L), the lithium vermiculite (LiV) flakes were sonicated in DI water for 0.5 hours to exfoliate them into monolayer V nanosheets. After centrifugation at 3000 rpm for 20 minutes, monolayer V nanosheets at a concentration of 1.38 mg mL⁻¹ were collected to remove multilayer vermiculite nanosheets and other bulky residues.

[0024] Step 1.3 Preparation of one-dimensional / two-dimensional composite structure ion-conducting membrane Weigh a certain amount of the nanocellulose dispersion obtained in step 1, and then add a certain amount of the vermiculite nanosheet dispersion obtained in step 2, and prepare a mixed dispersion according to a mass ratio of 0.1-0.75:1. The resulting dispersion was placed in a vacuum filtration apparatus and filtered at room temperature for 24-48 hours using a nylon membrane as a substrate to obtain a one-dimensional / two-dimensional composite ion-conducting membrane with a thickness of 10-40 micrometers.

[0025] Step 1.4 Place composite membranes of different proportions into a constant humidity device and maintain the conditions of 25 degrees Celsius and 95% humidity. Measure the XRD image of the membrane. Based on the peak elution of different peaks, the condition of the two channels in the composite membranes of different proportions can be obtained. The proportion of the two channels can be controlled by the addition ratio of one-dimensional material.

[0026] The third aspect of the present invention provides an application of a one-dimensional / two-dimensional composite ion-conducting membrane according to any embodiment of the first aspect of the present invention in an aqueous zinc battery.

[0027] The fourth aspect of the present invention provides an application of a one-dimensional / two-dimensional composite ion-conducting membrane according to any embodiment of the first aspect of the present invention in a solid electrolyte of an aqueous zinc battery.

[0028] Specifically, it includes the following steps: Step 2.1 Prepare the electrolyte by dissolving 28.75g of purchased ZnSO4·7H2O in 100mL of deionized water, sonicating and stirring in an ultrasonic instrument for 3-5 minutes to obtain a 1M ZnSO4 solution.

[0029] Step 2.2 Take 5 mL of the solution obtained in Step 1, and place the composite membranes with different ratios of 0.1-0.75:1 obtained in Step 1.3 into the solution and let them stand at room temperature for 1.5 h.

[0030] Step 2.3 After the solution in Step 2 has been left to stand for 1.5 hours, take out the composite membrane, wipe off the electrolyte on the surface, and place it in a constant temperature and humidity chamber at 25 degrees Celsius and 95% humidity for 3-6 hours.

[0031] Step 2.4 Under the constant temperature and humidity environment of Step 3, place the composite membrane into the fixture and continue to equilibrate for 0.5-1 hour.

[0032] Step 2.5 Connect the fixture to an impedance meter and measure the impedance spectrum in the range of 0.01 Hz to 1 MHz using two stainless steel plates as electrodes on an MFIA LCR. The intercept on the x-axis at high frequency is considered as the resistance of the electrolyte. Each sample is tested three times. The ionic conductivity (σ) is calculated using the following equation:

[0033] Where R, S, and L are the resistance, effective contact area, and thickness of various V-xCNF electrolytes, respectively.

[0034] Step 2.6 Nanoindentation tests were conducted on composite ion-conducting membranes with different proportions and commercial glass fiber membranes. The applied pressure was 300 uN. The Young's modulus and hardness of the membranes were calculated by the indentation depth and the degree of rebound.

[0035] Step 3.1 Under the conditions described in Step 2.3, the composite ion exchange membranes with different proportions processed in Step 2.3 are loaded into a CR2032 half-cell with zinc sheets as the positive and negative electrodes.

[0036] Step 3.2 Take 100 μL of the solution prepared in Step 2.1 and add it to a commercial glass fiber membrane as a control group.

[0037] Step 3.3 at 0.2 mA cm -2 0.1 mAh cm -2 Under the conditions, charge-discharge cycle tests were conducted on the Blue Electric system, with 100 cycles per test.

[0038] Step 3.4 Disassemble the button cell after 100 cycles to obtain the zinc negative electrode after cycling. Perform XRD characterization to determine the content of zinc negative electrode byproducts.

[0039] Step 3.5 The composite ion-conducting membranes with different ratios after cycling and the commercial glass fiber membrane were characterized by SEM to determine the degree of dendrite invasion.

[0040] Step 3.6 Under the conditions described in Step 2.3, the composite ion exchange membranes with different proportions treated in Step 2.3 are loaded into a CR2032 half-cell with zinc as the negative electrode and copper as the positive electrode to test the coulombic efficiency.

[0041] Step 3.7 Take 100 μL of the solution prepared in Step 2.1 and add it to a commercial glass fiber membrane as a control group.

[0042] 3. Beneficial effects Compared with the prior art, the advantages of this invention are: (1) The one-dimensional / two-dimensional composite structure ion-conducting membrane of the present invention can realize the control of the interlayer spacing, the control of the state of water between the interlayers, and the improvement of membrane mechanical properties.

[0043] (2) The one-dimensional / two-dimensional composite structure ion-conducting membrane described in this invention has good application in aqueous zinc batteries. It can suppress side reactions of the battery, reduce dendrite piercing, and has stable and reversible Zn stripping and deposition. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the one-dimensional / two-dimensional composite ion-conducting membrane of the present invention; Figure 2 The XRD patterns and peak areas of Examples 1-5 are shown below, measured at 25 degrees Celsius and 95% humidity.

[0045] Figure 3 The XRD test pattern for Example 6 was obtained at 25 degrees Celsius and 95% humidity.

[0046] Figure 4 The conductivity test graphs for Examples 1-6 were obtained under conditions of 25 degrees Celsius and 95% humidity.

[0047] Figure 5 The charts show the Young's modulus and hardness test results for Examples 1-6, measured at 25 degrees Celsius and under indoor humidity conditions.

[0048] Figure 6 Examples 7-8 were performed at 0.2 mA cm⁻¹ -2 0.1 mAh cm -2 Under the conditions, charge-discharge cycle tests were performed on the Blue Electric system, and the negative electrode XRD test image was obtained after 100 test cycles.

[0049] Figure 7 Example 7 at 0.2 mA cm -2 0.1 mAh cm -2 Under the conditions, charge-discharge cycle tests were performed on the Blue Electric system, and the SEM test image of the film surface was obtained after 100 test cycles.

[0050] Figure 8 Example 8 at 0.2 mA cm -2 0.1 mAh cm -2 Under the conditions, charge-discharge cycle tests were performed on the Blue Electric system, and the SEM test image of the film surface was obtained after 100 test cycles.

[0051] Figure 9 Examples 7-8 were performed at 1.0 mA cm⁻¹ -2 0.5 mAh cm -2 The Coulomb efficiency was obtained by testing on the Blue Electric system under the given conditions.

[0052] Figure 10 Examples 7-8 were performed at 0.5 mA cm⁻¹ -2 0.25 mAh cm -2 Under these conditions, long-cycle testing was conducted on the Blue Electric system. Detailed Implementation

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0054] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0055] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0056] Thickness, quantity, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0057] The present invention will be further described below with reference to specific embodiments.

[0058] Step 1: Method for preparing one-dimensional / two-dimensional composite structure ion-conducting membranes, including the following steps: Step 1.1 Preparation of one-dimensional nanocellulose dispersion: Weigh a certain amount of carboxylic acid cellulose and add it to deionized water. Stir mechanically at 500-1000 rpm for 1-2 hours at 15-30℃ to obtain a transparent and colorless dispersion.

[0059] Step 1.2 Preparation of two-dimensional material vermiculite nanosheet dispersion: Vermiculite nanosheets were exfoliated from expanded vermiculite using an ion exchange method. 1-2 g of expanded vermiculite was added to a saturated NaCl solution (26.47 wt%, 200 mL) and stirred under reflux at 110-130°C for 48 hours to replace interlayer Mg²⁺ cations with Na⁺. The vermiculite slurry was centrifuged at 8000-10000 rpm and repeatedly washed with 2-3 L of deionized water to remove residual salts. The received sodium-intercalated vermiculite (NaV) was dispersed in a saturated LiCl aqueous solution (7.8 wt%, 200 mL); the resulting mixture was maintained at 110-130°C for 24 hours under continuous magnetic stirring to further replace interlayer Na⁺ with Li⁺ cations, and then cooled to room temperature. After washing with excess deionized water (2-3 L), the lithium vermiculite (LiV) flakes were sonicated in DI water for 0.5 hours to exfoliate them into monolayer V nanosheets. After centrifugation at 3000 rpm for 20 minutes, monolayer V nanosheets at a concentration of 1.38 mg mL⁻¹ were collected to remove multilayer vermiculite nanosheets and other bulky residues.

[0060] Step 1.3 Preparation of one-dimensional / two-dimensional composite structure ion-conducting membrane Weigh a certain amount of the nanocellulose dispersion obtained in step 1, and then add a certain amount of the vermiculite nanosheet dispersion obtained in step 2, and prepare a mixed dispersion according to a mass ratio of 0.1-0.75:1. The obtained dispersion was placed in a vacuum filtration apparatus and filtered for 24-48 hours at room temperature using a nylon membrane as a substrate to obtain a one-dimensional / two-dimensional composite ion-conducting membrane, such as... Figure 1 As shown, its film thickness is 10-40 micrometers.

[0061] Step 1.4 Place composite membranes of different proportions into a constant humidity device and maintain the conditions of 25 degrees Celsius and 95% humidity. Measure the XRD image of the membrane. Based on the peak elution of different peaks, the condition of the two channels in the composite membranes of different proportions can be obtained. The proportion of the two channels can be controlled by the addition ratio of one-dimensional material.

[0062] Step 2: Testing method for one-dimensional / two-dimensional composite structure ion-conducting membranes, including the following steps: Step 2.1 Prepare the electrolyte by dissolving 28.75g of purchased ZnSO4·7H2O in 100mL of deionized water, sonicating and stirring in an ultrasonic instrument for 3-5 minutes to obtain a 1M ZnSO4 solution.

[0063] Step 2.2 Take 5 mL of the solution obtained in Step 1, and place the composite membranes with different ratios of 0.1-0.75:1 obtained in Step 1.3 into the solution and let them stand at room temperature for 1.5 h.

[0064] Step 2.3 After the solution in Step 2 has been left to stand for 1.5 hours, take out the composite membrane, wipe off the electrolyte on the surface, and place it in a constant temperature and humidity chamber at 25 degrees Celsius and 95% humidity for 3-6 hours.

[0065] Step 2.4 Under the constant temperature and humidity environment of Step 3, place the composite membrane into the fixture and continue to equilibrate for 0.5-1 hour.

[0066] Step 2.5 Connect the fixture to an impedance meter and measure the impedance spectrum in the range of 0.01 Hz to 1 MHz using two stainless steel plates as electrodes on an MFIA LCR. The intercept on the x-axis at high frequency is considered as the resistance of the electrolyte. Each sample is tested three times. The ionic conductivity (σ) is calculated using the following equation:

[0067] Where R, S, and L are the resistance, effective contact area, and thickness of various V-xCNF electrolytes, respectively.

[0068] Step 2.6 Nanoindentation tests were conducted on composite ion-conducting membranes with different proportions and commercial glass fiber membranes. The applied pressure was 300 uN. The Young's modulus and hardness of the membranes were calculated by the indentation depth and the degree of rebound.

[0069] Step 3: The application of one-dimensional / two-dimensional composite ion-conducting membranes in aqueous zinc battery testing methods includes the following steps: Step 3.1 Under the conditions described in Step 2.3, the composite ion exchange membranes with different proportions processed in Step 2.3 are loaded into a CR2032 half-cell with zinc sheets as the positive and negative electrodes.

[0070] Step 3.2 Take 100 μL of the solution prepared in Step 2.1 and add it to a commercial glass fiber membrane as a control group.

[0071] Step 3.3 at 0.2 mA cm -2 0.1 mAh cm -2 Under the conditions, charge-discharge cycle tests were conducted on the Blue Electric system, with 100 cycles per test.

[0072] Step 3.4 Disassemble the button cell after 100 cycles to obtain the zinc negative electrode after cycling. Perform XRD characterization to determine the content of zinc negative electrode byproducts.

[0073] Step 3.5 The composite ion-conducting membranes with different ratios after cycling and the commercial glass fiber membrane were characterized by SEM to determine the degree of dendrite invasion.

[0074] Step 3.6 Under the conditions described in Step 2.3, the composite ion exchange membranes with different proportions treated in Step 2.3 are loaded into a CR2032 half-cell with zinc as the negative electrode and copper as the positive electrode to test the coulombic efficiency.

[0075] Step 3.7 Take 100 μL of the solution prepared in Step 2.1 and add it to a commercial glass fiber membrane as a control group.

[0076] Example 1 A mixed dispersion was prepared by mixing the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 0:1. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a pure V-structure membrane. XRD analysis was performed at 25°C and 95% humidity.

[0077] like Figure 2 As shown in (V), the XRD test results show that only one peak exists at 6.8 degrees.

[0078] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the pure V composite membrane is 0.026 mS / cm. -1 It has a Young's modulus of 2.71 GPa and a hardness of 0.151 GPa. (High electrical conductivity indicates good electrochemical performance, while high Young's modulus and hardness indicate good mechanical properties, effectively resisting dendrite penetration.) Example 2 A mixed dispersion was prepared by mixing the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 0.1:1. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a V-0.1CNF composite membrane. XRD analysis was performed at 25°C and 95% humidity.

[0079] like Figure 2 As shown in (V-0.1CNF), the XRD test shows the existence of two peaks, one at 6 degrees and the other at 7 degrees, with different peak areas. By fitting, the ratio of peak areas can be found to be 1:1.

[0080] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the V-0.1CNF composite membrane is 0.117 mS / cm. -1 It has a Young's modulus of 2.93 GPa and a hardness of 0.212 GPa.

[0081] Example 3 like Figure 2As shown (V-0.25CNF), a mixed dispersion was prepared by taking the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 0.25:1. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a V-0.25CNF composite membrane. XRD analysis was performed at 25°C and 95% humidity.

[0082] The XRD test revealed the presence of two peaks, one at 6 degrees and the other at 7 degrees, with different peak areas. Through fitting, the ratio of peak areas was found to be 3:2.

[0083] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the V-0.25CNF composite membrane is 0.131 mS / cm. -1 It has a Young's modulus of 2.71 GPa and a hardness of 0.207 GPa.

[0084] Example 4 A mixed dispersion was prepared by mixing the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 0.5:1. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a V-0.5CNF composite membrane. XRD analysis was performed at 25°C and 95% humidity.

[0085] like Figure 2 As shown in the figure (V-0.5CNF), the XRD test shows the existence of two peaks, one at 6 degrees and the other at 7 degrees, with different peak areas. By fitting, the ratio of peak areas can be found to be 3.4:1.

[0086] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the V-0.5CNF composite membrane is 0.23 mS / cm. -1 It has a Young's modulus of 2.50 GPa and a hardness of 0.189 GPa.

[0087] Example 5 A mixed dispersion was prepared by mixing the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 0.75:1. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a V-0.75CNF composite membrane. XRD analysis was performed at 25°C and 95% humidity.

[0088] like Figure 2 As shown (V-0.75CNF), the XRD test results show that only one peak exists at 6 degrees.

[0089] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the V-0.75CNF composite membrane is 0.61 mS / cm.-1 It has a Young's modulus of 4.16 GPa and a hardness of 0.247 GPa.

[0090] Example 6 A mixed dispersion was prepared by mixing the nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 at a mass ratio of 1:0. This mixture was then vacuum filtered through a nylon membrane for 48 hours to obtain a pure CNF structure membrane. XRD analysis was performed at 25°C and 95% humidity.

[0091] like Figure 3 As shown, no peaks smaller than 10 degrees could be detected in the XRD test.

[0092] Following step 2, electrochemical impedance spectroscopy and nanoindentation testing revealed that the conductivity of the pure CNF composite film is 0.41 mS / cm. -1 It has a Young's modulus of 3.91 GPa and a hardness of 0.198 GPa.

[0093] Examples 1-6 demonstrate that a composite structure of one-dimensional / two-dimensional materials can be designed by changing the doping ratio of one-dimensional materials. With the continuous addition of one-dimensional materials, the number of channels at the 6-degree peak increases, and the ionic conductivity of the composite membrane also increases with the increase in the amount of one-dimensional material. Figure 4 This achieved the control of one-dimensional / two-dimensional material composite structures. Simultaneously, with the continuous addition of one-dimensional materials, the mechanical strength of the one-dimensional / two-dimensional composite membrane also increased significantly. Figure 5 Increasing the one-dimensional material content to 100% leads to the disappearance of the composite structure, resulting in a certain degree of decrease in both electrochemical and mechanical properties. The optimal concentration of CNF (Cellular Fluoride) yields the best electrical conductivity, strength, and overall performance.

[0094] Example 7 The nanocellulose dispersion and vermiculite nanosheet dispersion from step 1.3 were prepared into a mixed dispersion with a mass ratio of 0.75:1. The mixture was then vacuum filtered on a nylon membrane for 48 hours to obtain a V-0.75CNF composite membrane.

[0095] Proceed to step 2.3.

[0096] Proceed to step 3.1.

[0097] The tests performed in steps 3.3-3.6 show that after 100 cycles, no byproducts were generated on the zinc anode, and the membrane surface was not pierced by dendrites, indicating stable cycling. The coulombic efficiency remained at 98.0% after 400 cycles. Furthermore, at 0.5 mA cm⁻¹... -2 0.25 mAh cm -2Under certain conditions, it can be cycled for 800 times with a polarization voltage of 110mV.

[0098] Example 8 Take a commercial glass fiber membrane and process it in step 3.2.

[0099] The tests in steps 3.3-3.6 show that after 100 cycles, byproducts are generated at the zinc anode, the film surface is pierced by dendrites, and it cannot withstand long-term stable cycling. The coulombic efficiency decreases to 16.4% after 120 cycles. Furthermore, at 0.5 mA cm⁻¹... -2 0.25 mAh cm -2 Under these conditions, a polarization voltage of 60mV can only cycle 170 times.

[0100] Through Examples 7-8, it can be seen that... Figure 6 It can be seen that the application of one-dimensional / two-dimensional composite ion-conducting membrane in aqueous zinc batteries can effectively reduce the formation of zinc anode byproducts. At 8°, 16°, and 24°, no peaks appeared in the zinc anode of the battery in Example 7 using the one-dimensional / two-dimensional composite ion-conducting membrane as the electrolyte, which is the same as pure zinc sheet. In Example 8, the zinc anode showed obvious peaks in the battery using commercial glass fiber membrane as the electrolyte, proving that a large amount of byproduct Zn4(OH)6SO4·5H2O was generated.

[0101] Meanwhile, the composite structure membrane is not easily punctured by dendrites, from Figure 7 As can be seen, the film surface remains smooth after 100 charge-discharge cycles, while from... Figure 8 It can be seen that commercially available glass fiber membranes have poor resistance to dendrite penetration, and zinc dendrite-penetrating films already exist.

[0102] from Figure 9 As can be seen from the comparison with commercial glass fiber membranes, the composite ion-conducting membrane has a higher coulombic efficiency and can still maintain 98.0% after 400 cycles; while the coulombic efficiency of commercial glass fiber membranes rapidly declines to 16.7% after 120 cycles.

[0103] from Figure 10 It can be seen from this that it is possible to achieve a current of 0.5 mA cm -2 Under these conditions, it can be cycled for 900 cycles at a polarization voltage of 110mV for an extended period, which is superior to the 172 cycles of commercial glass fiber films.

[0104] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. A one-dimensional / two-dimensional composite ion-conducting membrane, characterized in that, Includes the following components: Carboxylic acid cellulose; and Vermiculite nanosheets; The XRD pattern of the composite structure ion-conducting membrane shows a peak at 6.0±0.3°. The composite structure ion-conducting membrane contains at least one sandwich structure formed sequentially by a first vermiculite nanosheet layer, a carboxylic acid cellulose layer, and a second vermiculite nanosheet layer. The composite structure ion-conducting membrane contains vermiculite nanosheets with an interlayer spacing of 1.40 ~ 1.57 nm, which is calculated by XRD. The peak area ratio at 7.0±0.3° to that at 6.0±0.3° in the XRD pattern of the composite ion-conducting membrane is less than 20%. The one-dimensional / two-dimensional composite structure ion-conducting membrane is used in aqueous zinc batteries.

2. The one-dimensional / two-dimensional composite ion-conducting membrane according to claim 1, characterized in that, The XRD pattern of the composite structure ion-conducting membrane shows no peak at 7.0±0.3°.

3. The one-dimensional / two-dimensional composite ion-conducting membrane according to claim 1, characterized in that, The thickness of the composite structure ion-conducting membrane is 10~60μm.

4. The one-dimensional / two-dimensional composite ion-conducting membrane according to claim 1, characterized in that, The mass ratio of carboxylic acid cellulose to vermiculite nanosheets in the composite ion-conducting membrane is (0.1~0.8):

1.

5. The method for preparing the one-dimensional / two-dimensional composite ion-conducting membrane according to any one of claims 1 to 4, characterized in that, Includes the following steps: Provides a mixed dispersion containing carboxylic acid cellulose and vermiculite nanosheets; The composite structure ion-conducting membrane was obtained by filtration on the substrate.

6. The application of the one-dimensional / two-dimensional composite ion-conducting membrane according to any one of claims 1 to 4 in aqueous zinc batteries.

7. The application of the one-dimensional / two-dimensional composite ion-conducting membrane according to any one of claims 1 to 4 in the solid electrolyte of an aqueous zinc battery.

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