A high-performance zinc-iodine battery separator and its modification process and application

Abstract

The present invention provides a high-performance zinc-iodine battery separator and its modification process and application. The modification process is as follows: 2,4,6-tris(4-aminophenyl)triazine and 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde react with pyruvic acid in a solvent, followed by rapid freezing at low temperature and cyclic degassing, and high-temperature reaction to obtain a yellow precipitate, which is washed and dried to obtain a covalent organic framework material; the covalent organic framework material and graphene are then applied to a glass fiber separator by suction filtration to obtain a zinc-iodine battery separator. The zinc-iodine battery separator prepared by the present invention has excellent hydrophilicity and a suitable pore size, which can promote the rapid transfer of Zn2+; its smaller pores can effectively hinder the shuttling of polyiodides. In addition, the rich carboxylic acid groups in the separator can form a chemically stable interface on the surface of the separator, slowing down the ion penetration rate and increasing the conductivity of the separator, effectively preventing unexpected reactions between iodide ions and zinc ions, thereby improving the cycle life and safety of the battery.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a high-performance zinc-iodine battery separator and a modification process and application thereof. Background Art

[0002] The use of traditional fossil fuels has led to energy crises and severe greenhouse gas emissions. Consequently, countries have set goals for carbon reduction and a transition to clean energy. The development of renewable energy is considered a key component of these goals. However, the high volatility of renewable energy grids presents challenges in their practical application. To achieve these goals, the development of efficient energy storage technologies is essential. This not only addresses the challenges of renewable energy volatility but also effectively promotes the development of clean energy, furthering carbon reduction goals.

[0003] Traditional lithium-ion batteries are widely used in digital electronics and new energy vehicles, but they have safety issues and high costs. Although traditional lead-acid batteries are low-cost and safe, their low volumetric energy density, poor cycle life, and environmental pollution have hindered their application and development in the energy storage field. Therefore, there is an urgent need to develop new energy storage battery systems that are low-cost, highly safe, and have a long lifespan to support the country's strategic goals of "carbon peak" and "carbon neutrality" while supporting the development of renewable energy. Renewable energy is subject to high volatility, so it is crucial to develop efficient energy storage technologies to balance grid fluctuations. The research and development of new energy storage battery systems will help solve the problems of traditional batteries and promote the realization of clean energy transformation.

[0004] Aqueous secondary battery systems offer numerous advantages, including high safety, low cost, environmental friendliness, and low production requirements. While their electrochemical window is not as wide as that of organic electrolyte systems, they offer higher ionic conductivity, enabling higher power density. Therefore, aqueous secondary batteries exhibit broad application prospects and strong competitiveness in large-scale electrochemical energy storage systems.

[0005] Aqueous secondary batteries primarily include monovalent alkali metal ion batteries and high-valent metal ion batteries. High-valent metal ion batteries have a moderate potential, which helps mitigate side reactions in aqueous electrolytes. Zinc, as an element, offers advantages such as high reserves, low cost, and strong corrosion resistance. Zinc negative electrodes have high theoretical specific capacity and good plating / stripping reversibility. Therefore, considering the comprehensive characteristics of zinc, it can be concluded that zinc has development potential and broad application prospects in aqueous secondary batteries.

[0006] Zinc-iodine secondary batteries using aqueous zinc salt solutions have many advantages, including fast reaction speed, good reversibility, and high energy / power density.3- The intermediate state will lead to serious shuttle effect. To solve this problem, measures need to be taken to improve the battery's discharge capacity, coulombic efficiency and cycle life.

[0007] The glass fiber separator commonly used in traditional zinc ion battery research has a problem, that is, the pore size is large, which makes it difficult to effectively block the phenomenon of polyiodide shuttle. In addition, the closure of the cation selective permeable membrane structure also leads to low conductivity of zinc ions, thus affecting the performance of the battery. Therefore, a novel membrane that can quickly conduct Zn 2+ The key to solving these problems lies in developing an efficient separator that can effectively block the shuttling of multiple iodides. By improving the design and material selection of the separator, the performance of zinc-ion batteries can be significantly improved, promoting their application in the field of energy storage.

[0008] Therefore, one of the current challenges in the field of zinc-iodine batteries is to develop a 3- Barrier efficiency and high Zn 2+ An integrated thin-layer separator with high transmittance can improve the discharge capacity, coulombic efficiency, and rate performance of zinc-iodine batteries. Solving this problem is crucial to further improving the performance of zinc-iodine batteries. Summary of the Invention

[0009] In view of this, the present invention proposes a high-performance zinc-iodine battery separator and its modification process and application.

[0010] The technical solution of the present invention is achieved as follows:

[0011] A modification process for a high-performance zinc-iodine battery separator comprises the following steps:

[0012] Step 1: reacting 2,4,6-tris(4-aminophenyl)triazine and 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde with pyruvic acid in a solvent to obtain a mixed solution A;

[0013] Step 2: The mixed solution A of step 1 is subjected to ultrasonic treatment, followed by rapid freezing at low temperature and degassing through circulation, and then placed in an oven for reaction to obtain a yellow precipitate, which is then filtered, washed, and vacuum-dried to obtain a covalent organic framework material;

[0014] Step 3: Grind the covalent organic framework material of step 2 and mix it with graphene, then dissolve it with methanol, and then perform ultrasonic treatment to obtain a mixed solution B. Filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane, and dry and slice the filter membrane to obtain a high-performance zinc-iodine battery membrane.

[0015] Furthermore, in step 1, the molar ratio of 2,4,6-tris(4-aminophenyl)triazine, 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and pyruvic acid is 1:1:3.3-3.7.

[0016] Furthermore, the molar ratio of the 2,4,6-tris(4-aminophenyl)triazine, 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and pyruvic acid is 1:1:3.5.

[0017] Furthermore, in step 1, the molar amount of the 2,4,6-tris(4-aminophenyl)triazine and the volume ratio of the solvent are 0.17 mmol:2.5-4.0 ml; the solvent is composed of o-dichlorobenzene and n-butanol, and the volume ratio of o-dichlorobenzene to n-butanol is 1-2:1-2.

[0018] Furthermore, in step 2, the low temperature is 77K, and the cyclic degassing condition is vacuum-filling with nitrogen, which is cycled at least 3 times, and the internal pressure is pumped to 10 -3 mbar.

[0019] Furthermore, in step 2, the washing solvents are acetone and methanol, and the washing is performed first with acetone and then with methanol; the reaction temperature in the oven is 80-160° C. and the reaction time is 48-96 hours; the vacuum drying temperature is 70-100° C. and the drying time is 4-6 hours.

[0020] Furthermore, in step 2, the reaction temperature in the oven is 100-120° C., and the reaction time is 48-72 hours. A reaction time that is too short will result in incomplete reaction, while a reaction time that is too long will result in waste of resources.

[0021] Furthermore, in step 3, the mass ratio of the covalent organic framework material to graphene is 2:0.8-1.4.

[0022] Furthermore, in step 3, the mass ratio of the covalent organic framework material to the graphene is 2:1.2. The mass ratio of the covalent organic framework material to the graphene determines the thickness of the prepared membrane.

[0023] Furthermore, in step 3, the ratio of the total mass of the covalent organic framework material and graphene to the volume of methanol is 20 mg:40-50 ml.

[0024] Furthermore, in step 3, the covalent organic framework material is ground into fine particles of 200-300 μm.

[0025] Furthermore, in step 3, the ultrasonic treatment time is 10-20 minutes; the drying temperature is 40-70° C. and the drying time is 3-6 hours; and the slices are cut into discs with a diameter of 18 mm using a slicer.

[0026] The invention discloses a high-performance zinc-iodine battery separator prepared by the modification process.

[0027] Furthermore, the zinc-iodine battery separator has a pore size range of 1.2-1.8 nm and a thickness of 0.5-1.2 mm.

[0028] Application of the high-performance zinc-iodine battery separator of the present invention in the preparation of zinc-iodine batteries.

[0029] Furthermore, the zinc-iodine battery includes a positive electrode, a negative electrode, an electrolyte and a high-performance zinc-iodine battery separator; the positive electrode is an activated carbon cloth loaded with elemental iodine; the negative electrode is a metal zinc foil or other zinc-containing metal alloy; and the electrolyte is a zinc salt aqueous solution.

[0030] Furthermore, the preparation process of the positive electrode of the iodine-loaded activated carbon cloth includes: mixing coconut shell carbon, carbon black and polyvinylidene fluoride adhesive in a mass ratio of 2:1-1.4:9-12, then adding solvent N-methylpyrrolidone, wherein the mass ratio of N-methylpyrrolidone to coconut shell carbon is 13-17:2, after stirring evenly, coating the slurry on carbon foil and drying it at 50-70°C for 4-6 hours, and cutting the obtained carbon foil into discs with a diameter of 9 mm with a slicer, and then placing it in an open iodine absorption bottle, placing the iodine bottle in a 75°C oven for 2-3 days and taking it out to obtain the positive electrode sheet.

[0031] Furthermore, the electrolyte of the zinc-iodine battery is a 1-5M ZnSO4 aqueous solution on the negative electrode side, and a 1-5M ZnSO4+0.4M ZnI mixed aqueous solution on the positive electrode side.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The high-performance zinc-iodine battery separator prepared by the present invention has excellent hydrophilicity and suitable pore size (1.2-1.8nm), which promotes the 2+ The rapid transfer of iodide and the effective restriction of polyiodide shuttling through microporous confinement and the construction of a chemically stable interface. Therefore, based on the synergistic effect of the above mechanisms, the high-performance zinc-iodine battery separator prepared by the present invention can effectively inhibit the shuttling of polyiodide, thereby significantly improving battery performance and cycle life.

[0034] (2) Through the modification process of the present invention, the carboxylic acid groups rich in the zinc-iodine battery membrane can form a chemically stable interface on the membrane surface, slowing down the penetration rate of ions and improving the conductivity of the membrane, effectively preventing the unexpected reaction between iodine ions and zinc ions, thereby improving the cycle life and safety of the battery.

[0035] (3) The high-performance zinc-iodine battery separator of the present invention has shown significant advantages in the application of zinc-iodine batteries compared to glass fiber separators. These advantages are mainly reflected in indicators such as cycle performance and coulombic efficiency. In energy storage secondary batteries, the high-performance zinc-iodine battery separator shows great application prospects. -2 At a high current density, the full battery provides a stable coulombic efficiency of over 90% and a cycle life of up to 800 hours, which shows that this high-performance zinc-iodine battery separator has great potential in improving battery performance and extending service life.

[0036] (4) The high-performance zinc-iodine battery separator of the present invention adopts a simple one-step synthesis process, and the preparation method is simple. In addition, the raw material cost is low and it has environmental protection characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a reaction mechanism diagram of the COF#1 material prepared in Example 1 of the present invention.

[0038] Figure 2 This is a physical picture of the COF#1 material prepared in Example 1 of the present invention.

[0039] Figure 3 This is a physical picture of the COF#1 membrane prepared in Example 1 of the present invention.

[0040] Figure 4 This is the X-ray diffraction pattern of the COF#1 membrane prepared in Example 1 of the present invention.

[0041] Figure 5 This is a contact angle diagram of the COF#1 membrane prepared in Example 1 of the present invention.

[0042] Figure 6 The COF#1 membrane prepared in Example 1 of the present invention is I3 - Ion permeability test results; Figure 6 (a) is the state diagram at the beginning of the test. Figure 6 (b) is the state diagram after standing for 1 hour.

[0043] Figure 7 This is a cross-sectional scanning electron microscope image corresponding to the COF#1 membrane prepared in Example 1 of the present invention.

[0044] Figure 8This is a comparison chart of the electrochemical impedance of a full battery assembled with the COF#1 membrane prepared in Example 1 of the present invention and a blank commercial glass fiber membrane.

[0045] Figure 9 This is a graph showing the cyclic voltammetry curves of a full cell assembled with the COF#1 membrane prepared in Example 1 of the present invention at different scan rates.

[0046] Figure 10 The graph shows the cyclic voltammograms of full cells assembled with blank commercial glass fiber separators at different scan rates.

[0047] Figure 11 This is a comparison chart of the peak current linear fitting of the cyclic voltammetry curves of the full battery assembled with the COF#1 membrane prepared in Example 1 of the present invention and a blank commercial glass fiber membrane.

[0048] Figure 12 This is a graph showing the cycling performance of a zinc-iodine battery assembled with the COF#1 diaphragm prepared in Example 1 of the present invention.

[0049] Figure 13 The zinc-iodine battery assembled with the COF#2 diaphragm prepared in Comparative Example 1 of the present invention was tested at a current density of 5 mA / cm 2 Scanning electron microscope image of zinc foil after 10 cycles under the same conditions. DETAILED DESCRIPTION

[0050] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0051] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0052] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0053] Example 1

[0054] Step 1: Add 0.17 mmol of 2,4,6-tris(4-aminophenyl)triazine, 0.17 mmol of 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and 0.6 mmol of pyruvic acid (60 μl) to a solvent consisting of 1.5 ml of o-dichlorobenzene and 1.5 ml of n-butanol to obtain a mixed solution A;

[0055] Step 2: The mixed solution A in step 1 was ultrasonically treated for 20 minutes, then rapidly frozen at 77K and degassed by vacuum-nitrogen cycle for 3 cycles. After thawing to room temperature, the solution was placed in a 120°C oven for 72 hours to obtain a yellow precipitate. The reaction mechanism is as follows: Figure 1As shown, according to the nitrogen adsorption isotherm curve, a yellow precipitate with a pore diameter of 1.7 nm was obtained. The yellow precipitate was first washed with 10 mL of acetone, then washed with 10 mL of methanol, and this cycle was repeated several times. The mixture was filtered and then vacuum-dried at 80 ° C for 6 hours to obtain a covalent organic framework material, as shown in FIG. Figure 2 As shown, it is recorded as COF#1.

[0056] Step 3: Grind the covalent organic framework material (COF#1) in step 2 for 10 minutes until the material is fine particles of 250 μm, mix it with commercial graphene in a mass ratio of 2:1.2, and then dissolve it together with methanol in a beaker. The ratio of the total mass of the covalent organic framework material and graphene to the volume of methanol is 20 mg:40 mL. Then, ultrasonicate for 20 minutes to obtain a mixed solution B. Then, filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane. Then, place the filter membrane in a vacuum drying oven at 50°C and dry it for 6 hours. After drying, use a slicer to cut it into discs with a diameter of 18 mm to obtain a zinc-iodine battery membrane, which is recorded as COF#1 membrane. The actual picture is as follows: Figure 3 shown.

[0057] The performance of the COF#1 membrane prepared in Example 1 of the present invention was tested, and the results are shown below.

[0058] like Figure 4 As shown in the figure, the results of the X-ray diffraction pattern of COF#1 membrane are given, which shows that COF#1 membrane has good crystallinity.

[0059] like Figure 5 The figure shows the contact angle of the COF#1 separator, which is 83°. This indicates that the prepared COF#1 separator has good hydrophilicity, which is attributed to the rich carboxylic acid groups in the COF#1 separator. The carboxylic acid groups can form a chemically stable interface on the separator surface, slowing the permeation rate of ions and improving the conductivity of the separator. This effectively prevents the unintended reaction between iodide ions and zinc ions, thereby improving the cycle life and safety of the battery.

[0060] like Figure 6 As shown, COF#1 membrane is used to - When testing ion permeability, Figure 6 As shown in (a), at the beginning of the test, the left side of the H-type glass battery is 1M ZnI2+0.1M I2 aqueous solution, the right side is aqueous solution, and the COF#1 separator is sandwiched in the middle; after standing for 1 hour, Figure 6 As shown in (b), the color change of the aqueous solution on the right is not obvious, which proves that the COF#1 membrane can effectively inhibit I3 - The shuttling of ions.

[0061] like Figure 7The figure shows a scanning electron micrograph of a cross-section of the COF#1 separator. It can be clearly seen that the underlying substrate is glass fiber, and the structure of the glass fiber supporting material is clearly visible. Furthermore, the zinc-iodine battery separator material is evenly coated on the glass fiber surface, demonstrating that the COF#1 separator material is well integrated with the glass fiber, forming a continuous and uniform coating. This material system exhibits good uniformity and consistency. This uniform coverage indicates that the zinc-iodine battery separator is very evenly distributed on the glass fiber surface, contributing to improved overall material performance.

[0062] Example 2

[0063] The COF#1 diaphragm prepared in Example 1 was used to assemble a zinc-iodine battery into a full battery, which was denoted as COF@GR@GF. At the same time, the COF#1 diaphragm was replaced with a blank commercial glass fiber diaphragm for zinc-iodine battery assembly into a full battery as a comparison, which was denoted as GF. The performance of the two was tested.

[0064] The tested zinc-iodine battery includes a positive electrode, a negative electrode, an electrolyte, and the zinc-iodine battery separator or a blank commercial glass fiber separator. The positive electrode is an activated carbon cloth loaded with iodine. The preparation process of the positive electrode includes: mixing coconut shell carbon, carbon black, and polyvinylidene fluoride adhesive in a mass ratio of 2:1:10, then adding solvent N-methylpyrrolidone, wherein the mass ratio of N-methylpyrrolidone to coconut shell carbon is 15:2, stirring evenly, coating the slurry on carbon foil and drying it at 60°C for 6 hours. The obtained carbon foil is cut into 9mm diameter discs with a slicer, then placed in an open iodine absorption bottle, and the iodine bottle is placed in a 75°C oven for 3 days to obtain the positive electrode.

[0065] The negative electrode is a metal zinc foil;

[0066] The negative electrode side of the zinc-iodine battery electrolyte is 400ul of a 2M ZnSO4 aqueous solution; the positive electrode side is 400ul of a mixed aqueous solution consisting of 2MZnSO4+0.4M ZnI.

[0067] Figure 8 A comparison of the electrochemical impedance of zinc-iodine full cells assembled with COF#1 separators and blank commercial glass fiber separators is presented. The results show that the COF#1 separator of the present invention exhibits lower charge transfer resistance in the full cell, indicating that the introduction of the covalent organic framework material prepared in this invention significantly improves charge transfer kinetics, which is of great significance for improving the performance of the full cell.

[0068] Figure 9 and Figure 10 The cyclic voltammetry curves of the zinc-iodine full cell assembled with COF#1 membrane and blank commercial glass fiber membrane are given respectively. Figure 11A comparison chart of the peak current linear fitting of the cyclic voltammetry curves of the two assembled into a zinc-iodine full battery is given. Figure 9 and Figure 10 It can be seen that compared with the blank commercial glass fiber separator, the COF#1 separator of the present invention exhibits a higher peak current and a smaller polarization potential, which indicates that its electrochemical performance is superior. Figure 10 The linear fitting results show that COF#1 membrane has a larger slope, indicating that the Zn 2+ The mobility of COF#1 membrane is significantly increased. The actual calculation results also verify this point. 2+ The mobility is 2.3×10 -10 , while the blank commercial glass fiber separator has Zn 2+ The mobility is 9.9×10 -11 Therefore, the use of the covalent organic framework material of the present invention in the preparation of zinc-iodine battery separators can significantly increase the Zn 2+ Mobility, speed up I2 / I - The redox kinetics process is favorable for the zinc deposition / stripping behavior.

[0069] Figure 12 The cycling performance of the zinc-iodine full battery assembled with COF#1 separator and blank commercial glass fiber separator is shown. The results show that COF#1 separator performs well compared with the blank commercial glass fiber separator, and it shows excellent cycling stability. -2 At a current density of 1.5 GHz, the full cell provides a stable coulombic efficiency of over 90% and can be cycled continuously for 800 hours.

[0070] Comparative Example 1

[0071] This comparative example is compared with Example 1: the pyruvic acid in step 1 is replaced with acetic acid to prepare a high-performance zinc-iodine battery separator, and the rest is the same as Example 1.

[0072] The modification process of the high-performance zinc-iodine battery separator of this comparative example comprises the following steps:

[0073] Step 1: 0.17 mmol of 2,4,6-tris(4-aminophenyl)triazine, 0.17 mmol of 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and 0.6 mmol of acetic acid (60 μl) were added to a solvent consisting of 1.5 ml of o-dichlorobenzene and 1.5 ml of n-butanol to obtain a mixed solution A;

[0074] Step 2: The mixed solution A in step 1 was ultrasonically treated for 20 minutes, then rapidly frozen at 77K and degassed by vacuum-nitrogen cycle for 3 cycles. After thawing to room temperature, the solution was placed in a 120°C oven for 72 hours to obtain a precipitate, which was first washed with 10 mL of acetone, then washed with 10 mL of methanol, and this cycle was repeated several times. The precipitate was filtered and then vacuum-dried at 80°C for 6 hours to obtain a covalent organic framework material, which was recorded as COF#2.

[0075] Step 3: Grind the covalent organic framework material (COF#2) for 10 minutes until the material is fine particles of 250um, and then mix it with commercial graphene in a mass ratio of 2:1.2, and then dissolve it together with methanol in a beaker. The ratio of the total mass of the covalent organic framework material and graphene to the volume of methanol is 20mg:40mL. Then, ultrasonicate for 20 minutes to obtain a mixed solution B, and then filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane. Then, place the filter membrane in a vacuum drying oven at 50°C and dry it for 6 hours. After drying, use a slicer to cut it into discs with a diameter of 18mm to obtain a zinc-iodine battery membrane.

[0076] like Figure 13 As shown, the zinc-iodine battery separator prepared in this comparative example was used to assemble a zinc-iodine battery, and then 2 The zinc foil was scanned by electron microscope after 10 cycles under the same conditions. As can be seen from the figure, there are a large number of zinc dendrites and zinc foil collapse on the surface of the negative electrode zinc foil, which leads to poor battery cycle performance and low coulombic efficiency. The results show that the present invention improves the performance of the zinc-iodine battery separator by mixing 2,4,6-tris(4-aminophenyl)triazine and 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde in an appropriate amount of acetone, thereby effectively improving the performance of the assembled zinc-iodine battery.

[0077] Comparative Example 2

[0078] This comparative example is compared with Example 1: In this comparative example, graphene is not added to prepare the zinc-iodine battery separator, and the rest is the same as Example 1.

[0079] The modification process of the high-performance zinc-iodine battery separator of this comparative example comprises the following steps:

[0080] Step 1: 0.17 mmol of 2,4,6-tris(4-aminophenyl)triazine, 0.17 mmol of 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and 0.6 mmol of pyruvic acid (60 μl) were added to a solvent consisting of 1.5 ml of o-dichlorobenzene and 1.5 ml of n-butanol to obtain a mixed solution A;

[0081] Step 2: The mixed solution A in step 1 was ultrasonically treated for 20 minutes, then rapidly frozen at 77K and degassed by vacuum-nitrogen cycle for 3 cycles. After thawing to room temperature, the solution was placed in a 120°C oven for 72 hours to obtain a yellow precipitate. The reaction mechanism is as follows: Figure 1 As shown, according to the nitrogen adsorption isotherm curve, a yellow precipitate with a pore diameter of 1.7 nm was obtained. The yellow precipitate was first washed with 10 mL of acetone, then washed with 10 mL of methanol, and this washing cycle was repeated multiple times. The mixture was filtered and then vacuum-dried at 80°C for 6 hours to obtain a covalent organic framework material, which was recorded as COF#1.

[0082] Step 3: Grind the covalent organic framework material (COF#1) in step 2 for 10 minutes until the material is fine particles of 250 μm, and then dissolve it in methanol in a beaker. The ratio of the total mass of the covalent organic framework material to the volume of methanol is 20 mg:40 mL. Then, ultrasonicate for 20 minutes to obtain a mixed solution B. Then, filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane. Then, place the filter membrane in a vacuum drying oven at 50°C and dry it for 6 hours. After drying, cut it into discs with a diameter of 18 mm with a slicer to obtain a zinc-iodine battery membrane.

[0083] Compared with Example 1, the zinc-iodine battery separator prepared in this comparative example exhibited poor conductivity and mechanical stability. This indicates that the absence of graphene reduced the separator's conductivity, impacting the battery's charge-discharge efficiency and cycle life, thereby reducing battery performance.

[0084] Furthermore, when the zinc-iodine battery separator prepared in this comparative example was used in the assembly of a zinc-iodine battery, the performance and safety of the zinc-iodine battery were significantly reduced. This indicates that even without the addition of graphene, the internal resistance of the battery increases, energy loss increases during discharge, and the power performance of the battery is reduced. Furthermore, the mechanical strength and stability of the separator are weakened, making it prone to perforation or damage, affecting the safety of the battery.

[0085] Therefore, adding a reasonable proportion of graphene in the process of preparing zinc-iodine battery separators can effectively improve the conductivity and mechanical stability of the separator, and improve the performance and safety of zinc-iodine batteries.

[0086] Example 3

[0087] Step 1: 0.17 mmol of 2,4,6-tris(4-aminophenyl)triazine, 0.17 mmol of 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and 0.63 mmol of pyruvic acid were added to a solvent consisting of 1.0 ml of o-dichlorobenzene and 2.0 ml of n-butanol to obtain a mixed solution A;

[0088] Step 2: The mixed solution A in step 1 was ultrasonically treated for 20 minutes, then rapidly frozen at 77K and degassed by vacuum-nitrogen cycle for 3 times. After thawing to room temperature, the solution was placed in an oven at 100°C for 86 hours to obtain a yellow precipitate. The reaction mechanism is as follows: Figure 1 As shown, according to the nitrogen adsorption isotherm curve, a yellow precipitate with a pore diameter of 1.7 nm was obtained. The yellow precipitate was first washed with 10 mL of acetone, then washed with 10 mL of methanol, and this washing cycle was repeated multiple times. The mixture was filtered and then vacuum-dried at 70°C for 6 hours to obtain a covalent organic framework material, which was recorded as COF#3.

[0089] Step 3: Grind the covalent organic framework material (COF#3) of step 2 for 10 minutes until the material is fine particles of 250um, and then mix it with commercial graphene in a mass ratio of 2:1.4, and then dissolve it together with methanol in a beaker. The ratio of the total mass of the covalent organic framework material and graphene to the volume of methanol is 20mg:50mL. Then, ultrasonicate for 15 minutes to obtain a mixed solution B, and then filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane. Then, place the filter membrane in a vacuum drying oven at 60°C and dry it for 4 hours. After drying, cut it into discs with a diameter of 18mm with a slicer to obtain a zinc-iodine battery membrane.

[0090] Example 4

[0091] Step 1: 2,4,6-tris(4-aminophenyl)triazine, 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and 0.56 mmol of pyruvic acid were added to a solvent consisting of 2.0 ml of o-dichlorobenzene and 1.0 ml of n-butanol to obtain a mixed solution A;

[0092] Step 2: The mixed solution A in step 1 was ultrasonically treated for 20 minutes, then quickly frozen at 77K and degassed by vacuum-nitrogen filling cycles for 3 cycles. After thawing to room temperature, it was placed in a 160°C oven and reacted for 54 hours to obtain a yellow precipitate. According to the nitrogen adsorption isotherm curve, a yellow precipitate with a pore diameter of 1.7 nm was obtained. The yellow precipitate was first washed with 10 mL of acetone and then with 10 mL of methanol. This cycle was repeated several times, filtered, and then vacuum-dried at 100°C for 4 hours to obtain a covalent organic framework material, recorded as COF#4.

[0093] Step 3: Grind the covalent organic framework material (COF#4) of step 2 for 10 minutes until the material is fine particles of 300um, and then mix it with commercial graphene in a mass ratio of 2:0.8, and then dissolve it together with methanol in a beaker. The ratio of the total mass of the covalent organic framework material and graphene to the volume of methanol is 20mg:45mL. Then, ultrasonicate for 10 minutes to obtain a mixed solution B, and then filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane. Then, place the filter membrane in a vacuum drying oven at 40°C and dry it for 5 hours. After drying, use a slicer to cut it into discs with a diameter of 18mm to obtain a zinc-iodine battery membrane.

[0094] Through experiments, it was found that the zinc-iodine battery separators prepared in Examples 3 and 4 of the present invention also had good performance compared with Example 1; in addition, the zinc-iodine battery separators prepared in Examples 3 and 4 were used to assemble zinc-iodine batteries and then tested for performance. The zinc-iodine batteries had high conductivity and mechanical stability, and also showed excellent performance.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A modification process for a high-performance zinc-iodine battery separator, characterized in that: The following steps are involved: Step 1: reacting 2,4,6-tris(4-aminophenyl)triazine and 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde with pyruvic acid in a solvent to obtain a mixed solution A; Step 2: The mixed solution A of step 1 is subjected to ultrasonic treatment, followed by rapid freezing at low temperature and degassing through circulation, and then placed in an oven for reaction to obtain a yellow precipitate, which is then filtered, washed, and vacuum-dried to obtain a covalent organic framework material; Step 3: Grind the covalent organic framework material of step 2 and mix it with graphene, then dissolve it with methanol, and then perform ultrasonic treatment to obtain a mixed solution B. Filter the mixed solution B onto a glass fiber membrane to obtain a filter membrane, and dry and slice the filter membrane to obtain a high-performance zinc-iodine battery membrane.

2. The modification process of the high performance zinc-iodine battery separator according to claim 1, characterized in that: In step 1, the molar ratio of 2,4,6-tris(4-aminophenyl)triazine, 4,4',4"-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and pyruvic acid is 1:1:3.3-3.

7.

3. The modification process of the high performance zinc-iodine battery separator according to claim 1, characterized in that: In step 1, the molar amount of the 2,4,6-tris (4-aminophenyl) triazine and the volume ratio of the solvent are 0.17 mmol: 2.5 to 4.0 ml; the solvent is composed of o-dichlorobenzene and n-butanol, and the volume ratio of the o-dichlorobenzene and n-butanol is 1-2:1-2.

4. The modification process of the high performance zinc-iodine battery separator according to claim 1, characterized in that: In step 2, the washing solvents are acetone and methanol, and the washing is first performed with acetone and then with methanol; the reaction temperature in the oven is 80-160° C. and the reaction time is 48-96 hours; the vacuum drying temperature is 70-100° C. and the drying time is 4-6 hours.

5. The modification process of the high performance zinc-iodine battery separator according to claim 1, characterized in that: In step 3, the mass ratio of the covalent organic framework material to the graphene is 2:0.8-1.4; and the ratio of the total mass of the covalent organic framework material and the graphene to the volume of methanol is 20 mg:40-50 ml.

6. The modification process of the high performance zinc-iodine battery separator according to claim 1, characterized in that: In step 3, the ultrasonic treatment time is 10-20 minutes; the drying temperature is 40-70° C. and the drying time is 3-6 hours; and the slices are cut into discs with a diameter of 18 mm using a slicer.

7. A high-performance zinc-iodine battery separator prepared by the modification process according to any one of claims 1 to 6.

8. The high-performance zinc-iodine battery separator according to claim 7, characterized in that: The zinc-iodine battery separator has a pore size of 1.2-1.8 nm and a thickness of 0.5-1.2 mm.

9. Use of the high-performance zinc-iodine battery separator prepared by the modification process according to any one of claims 1 to 6 or the high-performance zinc-iodine battery separator according to any one of claims 7 to 8 in the preparation of zinc-iodine batteries.

10. The use according to claim 9, characterized in that The zinc-iodine battery comprises a positive electrode, a negative electrode, an electrolyte and a high-performance zinc-iodine battery separator; the positive electrode is an activated carbon cloth loaded with elemental iodine; the negative electrode is a metal zinc foil or other metal alloy containing zinc; and the electrolyte is a zinc salt aqueous solution.

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