Preparation method of lithium battery silicon negative electrode binder

Abstract

The invention discloses a preparation method of a lithium battery silicon negative electrode binder, and relates to the technical field of lithium ion batteries. Lignosulfonate is used as a main binder skeleton, sodium alginate is introduced to provide flexibility and an ion transmission channel, tannic acid provides super-strong polyphenol hydrogen bond adhesion, citric acid is used as a cross-linking agent to form a stable covalent network, and the binding force is improved. Carboxyl on citric acid and hydroxyl or amido on the polymer are subjected to esterification or amidation reaction to form a cross-linked network, a high-density dynamic hydrogen bond network is formed, the lithium battery silicon negative electrode binder is endowed with excellent toughness, stress is effectively buffered, and a silicon negative electrode is prevented from cracking.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically a method for preparing a lithium-ion battery silicon anode binder. Background Technology

[0002] Traditional graphite anodes have a low theoretical specific capacity, which is difficult to meet development requirements. Silicon-based anodes are considered the most promising next-generation anode materials due to their high theoretical specific capacity and abundant natural resources. However, silicon undergoes drastic volume expansion during charging and discharging, leading to repeated rupture and reconstruction of the solid electrolyte interface (SEI), damage to the electrode structure, and rapid capacity decay, which severely restricts its cycle life and practical applications.

[0003] In the development of silicon-based anodes, binders play a crucial role. Currently, polyimide is widely used as a binder for lithium-ion batteries. However, the synthesis of polyimide binders requires highly polar and toxic solvents, involves cumbersome steps, is costly, and causes significant environmental pollution, severely hindering its industrial application. Therefore, developing a binder with high ion transport efficiency and environmental friendliness is essential. This invention proposes a method for preparing a lithium-ion battery silicon anode binder to solve the aforementioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a lithium-ion battery silicon anode binder to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a lithium-ion battery silicon anode binder includes the following steps: S1: Add deionized water and sodium alginate to the reactor, stir at 50~60℃, then add sodium lignosulfonate, control the reaction temperature at 25~35℃, continue stirring, cool, and obtain premixed solution a. S2: Dissolve tannic acid in deionized water, and control the temperature at 30~35℃ to obtain a tannic acid solution; S3: Dissolve citric acid in deionized water, controlling the temperature at 20~25℃, to obtain a citric acid solution; S4: Slowly add triethanolamine to premix solution a, adjust the pH value to 8.0~9.0, and obtain premix solution b; S5: Maintain the stirring speed of premixed solution b at 150~200 rpm, slowly add tannic acid solution over 20~30 min, increase the stirring speed to 250~300 rpm, react for 15~30 min, slowly add citric acid solution over 20~40 min, continue stirring for 30~60 min, use deionized water to adjust the solid content of the mixture, and obtain lithium battery silicon anode binder.

[0006] Furthermore, in step S1, the mass ratio of deionized water, sodium alginate, and sodium lignosulfonate is (8.5~9.5):(2~4):(6~8).

[0007] Furthermore, in step S2, the mass ratio of tannic acid to deionized water is (1.5~2.5):(12.5~17.5).

[0008] Furthermore, in step S3, the mass ratio of citric acid to deionized water is (1~2):(4~6).

[0009] Furthermore, in step S5, the lithium-ion battery silicon anode binder comprises the following components by weight: 10-25 parts of tannic acid, 10-20 parts of citric acid, 10-20 parts of sodium alginate, 70-90 parts of sodium lignosulfonate, and 0.9-1 parts of triethanolamine.

[0010] Furthermore, in step S5, the solid content of the mixed system is 10-15%.

[0011] In the above technical solution, lignin sulfonate is used as the main binder skeleton, sodium alginate provides flexibility and ion transport channels, tannic acid provides adhesion, and citric acid acts as a crosslinking agent to form a stable covalent network. Citric acid forms a crosslinked network through esterification / amidation reactions between its carboxyl groups and the hydroxyl / amine groups on the polymer. Sodium lignin sulfonate provides rigid support and dispersibility, while sodium alginate provides flexibility and ion transport channels. The polyphenolic structure of tannic acid can form strong hydrogen bonds or coordination bonds with the carboxyl groups of sodium alginate, while the carboxyl groups of citric acid may participate in esterification reactions, further enhancing network toughness. Tannic acid provides super-strong polyphenolic hydrogen bond adhesion, and citric acid forms a stable covalent crosslinked network through heat treatment, providing the material with high strength and modulus, forming a high-density dynamic hydrogen bond network, endowing the material with excellent toughness, effectively buffering stress, and preventing silicon anode cracking. During charging and discharging, the silicon anode undergoes volume changes. Sodium alginate polymer chains bind to the surface of silicon particles via hydrogen bonds. The hydrogen bond network between the chains has the characteristics of reversible breakage and recombination. When the silicon expands in volume, the hydrogen bonds temporarily break to absorb stress; when the volume shrinks, the hydrogen bonds reform, restoring the binder network to its original state. This gives the material a deformation capability similar to "self-healing". This dynamic adaptability effectively buffers the mechanical stress caused by volume changes and prevents the electrodes from cracking or pulverizing.

[0012] Furthermore, the lithium-ion battery silicon anode binder can also be prepared by the following process: Step 1: Dissolve sodium alginate in phosphate buffer solution, adjust the pH to 6-7.2, then add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide) and NHS (N-hydroxysuccinimide), stir, then add polyetheramine, heat to react, and obtain composite sodium alginate. Step 2: Dissolve the composite sodium alginate in deionized water, then add sodium lignosulfonate, porous inorganic filler, and lithium polyacrylate, and continue stirring to obtain a premixed solution; Step 3: Add triethanolamine to the premixed solution, adjust the pH to 8.0~9.0, then add tannic acid solution and citric acid solution, and use deionized water to adjust the solid content of the solution to obtain lithium battery silicon anode binder.

[0013] In the above technical solution, sodium alginate, under the action of EDC and NHS, activates the carboxyl groups on sodium alginate. The amino groups on polyetheramine form amide bonds with the activated carboxyl groups, grafting polyetheramine onto the molecular chain of sodium alginate. The flexible segments of polyetheramine can enhance the cohesive strength and toughness of the binder. The catechol structure on the composite sodium alginate is further combined with porous inorganic fillers and lithium polyacrylate through hydrogen bonding and metal coordination. The porous inorganic filler can increase the specific surface area of ​​the binder and enrich the ion transport channels, effectively improving the charge transport capacity and the utilization rate of silicon-based anode surface active materials. Sodium alginate can be embedded between the layers of porous inorganic fillers. The long chain structure of lithium polyacrylate forms a steric hindrance structure on the particle surface, which can effectively prevent secondary agglomeration between particles, improve dispersibility, and maintain coating uniformity. Its active lithium content can replenish the loss of active lithium during the first charge and discharge of the battery, improving the first coulombic efficiency.

[0014] Furthermore, in step one, the compound sodium alginate includes the following components by mass: 1-2 parts sodium alginate, 100-120 parts phosphate buffer, 1.8-2 parts EDC, 2.3-2.5 parts NHS, and 1-3 parts polyetheramine.

[0015] Furthermore, the mass ratio of the composite sodium alginate, sodium lignosulfonate, porous inorganic filler, and lithium polyacrylate is (1~2):(5~10):0.5:(1~5).

[0016] Furthermore, the concentration of the phosphate buffer solution is 0.1~0.3M.

[0017] Furthermore, the porous inorganic filler is prepared by the following process: Step (1): Add zinc nitrate and ferric nitrate to 2-methylimidazole, stir, then add N,N-dimethylformamide (DMF), heat to react, after the reaction is complete, centrifuge, dry to obtain MOFs; Step (2): Add graphene oxide to an ethanol solution, disperse it, then add MOFs, heat to react, filter and calcine after the reaction is complete to obtain porous inorganic filler.

[0018] In the above technical solution, zinc and iron ions are used as a bimetallic source. Compared with the single metal structure, the structure is more stable and the electronic structure of the metal-organic framework material can be controlled. It also has high capacity and stability, comprehensively improving the energy density of the negative electrode binder, enhancing the conductivity of the binder, and enriching the ion transport channels in the negative electrode binder. By combining MOFs with graphene oxide, the active functional groups (hydroxyl or carboxyl groups) on the graphene oxide are coordinated with the metal nodes on the MOFs, thereby obtaining a porous composite structure. The sheet-like two-dimensional structure of graphene oxide has a large specific surface area, which can increase the porosity of the binder, effectively buffer the volume expansion of the active material during charging and discharging, maintain structural integrity, and significantly extend the service life of the battery material.

[0019] Furthermore, the mass ratio of zinc nitrate to 2-methylimidazole is 1:(2~5).

[0020] Furthermore, the molar ratio of zinc nitrate to ferric nitrate is (1.5~3):1.

[0021] Furthermore, the mass ratio of graphene oxide, DMF, and MOFs is (1~5):(20~100):(5~25).

[0022] Furthermore, the calcination process conditions are: temperature 500~600℃, calcination time 1~4h.

[0023] Furthermore, the concentration of the ethanol solution is 70-80 vt.

[0024] An application of a lithium-ion battery silicon anode binder includes the following processes: Step 1: Weigh out silicon powder and conductive agent and premix them in a high-speed disperser at 40-60 rpm for 5 minutes to obtain dry powder; Step 2: Weigh the above lithium-ion battery silicon anode binder solution, add the dry powder, mix at a low speed of 40-60 rpm for 5 minutes, then transfer to a planetary mixer and stir at a speed of 40-60 rpm or 1200 rpm for 60 minutes. Then degas and stir at a speed of 20-30 rpm or 900 rpm for 15 minutes to obtain a uniform slurry. During the stirring process, the temperature is controlled at 20-30℃ to obtain the electrode slurry. The solid mass ratio of silicon powder, conductive agent, and lithium-ion battery silicon anode binder is (75-85):10:15. Step 3: Coat a copper foil with a wet film thickness of 150 μm, dry continuously in an oven at 85°C for 2-3 min, and immediately heat-treat in an oven at 150°C for 2-3 min to complete the esterification and crosslinking reaction of citric acid. Step 4: Cut the silicon electrode sheets into round pieces using a slicer. Assemble the button cell using the silicon electrode sheets, lithium metal sheet, separator, and argon atmosphere. The electrolyte is a 1-3 mol / L mixture of EC (ethylene carbonate) and DEC (diethyl carbonate), with a volume ratio of EC to DEC of 1:(1-3). The electrode sheets are compacted using a roller press, with a compaction density of 1.4-1.5 g / cm³. 3 .

[0025] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses lignin sulfonate as the main binder skeleton, sodium alginate provides flexibility and ion transport channels, tannic acid provides adhesion, and citric acid as a crosslinking agent to form a stable covalent network. It forms a crosslinking network through esterification / amidation reactions between carboxyl groups and hydroxyl / amine groups on the polymer. Sodium lignin sulfonate provides rigid support and dispersibility, while sodium alginate provides flexibility and ion transport channels.

[0026] 2. The lithium-ion battery silicon anode binder of the present invention has high strength and modulus, excellent toughness, and can effectively buffer stress and prevent the silicon anode from cracking.

[0027] 3. The preparation process of this invention does not use toxic or harmful substances and meets environmental protection requirements.

[0028] 4. This invention modifies sodium alginate to enhance the cohesive strength and toughness of the binder. It is then combined with porous inorganic fillers and lithium polyacrylate. The porous inorganic fillers increase the specific surface area of ​​the binder and enrich ion transport channels, effectively improving charge transport capacity and the utilization rate of silicon-based anode surface active materials. The presence of active lithium replenishes the loss of active lithium during the first charge and discharge cycle, improving the initial coulombic efficiency. Using a zinc-iron bimetallic source, the prepared metal-organic framework material has a more stable structure, possessing both high capacity and stability, comprehensively improving the energy density of the anode binder and enriching the ion transport channels within it. Combining MOFs with graphene oxide increases the pore structure of the binder, effectively buffering the volume expansion of active materials during charge and discharge, maintaining structural integrity, and significantly extending the battery material's lifespan. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the following specific embodiments, unless otherwise specified, the number of “parts” refers to parts by mass; Silicon powder, purity 99%, D50: 2~50μm, dielectric constant: 3.88; The conductive agent is conductive carbon black, model SPLi; Copper foil, 8μm thick; Lithium metal sheet, 15.8mm in diameter and 0.6mm thick; Diaphragm, model Celgard 2400; Button battery, battery case model CR2023; Sodium lignosulfonate, sourced from Shandong Chemical Co., Ltd.; Sodium alginate is sourced from Shandong Haoyang Seaweed Industry Co., Ltd. Tannic acid, sourced from Guiyang Beilong Chemical Co., Ltd.; Citric acid, sourced from Shandong Lemon Biochemical Co., Ltd.; Triethanolamine, 99% pure, sourced from Zibo Zhongcheng Chemical Co., Ltd., Shandong Province. Example 1:

[0031] A method for preparing a lithium-ion battery silicon anode binder includes the following steps: S1: Add 7000g of 50℃ deionized water to the reactor, maintain the system temperature at 55℃, slowly add 200g of sodium alginate at a stirring speed of 200rpm for 20min to prevent sodium alginate from agglomerating, stir until sodium alginate is completely dissolved, continue stirring for 1h, slowly add 600g of sodium lignosulfonate, control the system temperature at 35℃, stir for 2h to form a homogeneous solution without particles, add 1800g of deionized water, stir for 1h, and cool to 25℃; S2: Dissolve 150g of tannic acid in 1250g of deionized water, and control the system temperature at 30℃ to obtain a pale yellow homogeneous solution without particles. S3: Dissolve 100g of citric acid in 400g of deionized water, stir until completely transparent, and control the temperature at 25℃; S4: Stir the premixed liquid reactor at 150 rpm, slowly add triethanolamine to the premixed liquid, monitor the pH value in real time, and adjust the pH value to 8.0; S5: Maintain a stirring speed of 150 rpm, slowly add 1400 g of tannic acid solution over 20 min, increase the stirring speed to 250 rpm, react for 15 min, slowly add 500 g of citric acid solution over 20 min, continue stirring for 30 min to ensure that the system is homogeneous, and use deionized water to adjust the solid content of the solution to 10% to obtain the lithium battery silicon anode binder. The application of a lithium-ion battery silicon anode binder includes the following steps: Step 1: Weigh 3750g of silicon powder and 500g of conductive agent and premix them in a high-speed disperser at 40rpm for 5min to obtain dry powder; Step 2: Weigh 7500g of the above lithium-ion battery silicon anode binder solution, add the dry powder, mix at a low speed of 40rpm for 5min, then transfer to a planetary mixer and stir at a speed of 1200rpm for 60min, then degas and stir at a speed of 900rpm for 15min to obtain a uniform slurry. During the stirring process, the temperature is controlled at 20℃ to obtain the electrode slurry; the solid mass ratio of silicon powder, conductive agent and lithium-ion battery silicon anode binder is 75:10:15. Step 3: Coat the copper foil with a wet film thickness of 150 μm, dry it continuously in an oven at 85°C for 2 min, and immediately put it into an oven at 150°C for 2 min of heat treatment to complete the esterification and crosslinking reaction of citric acid. Step 4: Cut the silicon electrode sheets into 10mm diameter round pieces using a slicer. Assemble the button cell with the silicon electrode sheets, lithium metal sheet, separator, and argon atmosphere. The electrolyte is a 1mol / L mixture of EC (ethylene carbonate) and DEC (diethyl carbonate), with a volume ratio of EC to DEC of 1:1. The electrode sheets are compacted using a roller press, and the compaction density of the cooling roller is 1.5g / cm³. 3 . Example 2:

[0032] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the lithium-ion battery silicon anode binder comprises the following components by mass: 15 parts of tannic acid, 15 parts of citric acid, 10 parts of sodium alginate, 90 parts of sodium lignosulfonate, and 1 part of triethanolamine, and the remaining methods are the same as in Example 1. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 3:

[0033] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the lithium-ion battery silicon anode binder comprises the following components by weight: 25 parts of tannic acid, 15 parts of citric acid, 20 parts of sodium alginate, 70 parts of sodium lignosulfonate, and 0.9 parts of triethanolamine; the remaining methods are the same as in Example 1. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 4:

[0034] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the lithium-ion battery silicon anode binder comprises the following components by weight: 10 parts of tannic acid, 20 parts of citric acid, 15 parts of sodium alginate, 75 parts of sodium lignosulfonate, and 0.9 parts of triethanolamine; the remaining methods are the same as in Example 1. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 5:

[0035] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the lithium-ion battery silicon anode binder comprises the following components by weight: 10 parts of tannic acid, 10 parts of citric acid, 15 parts of sodium alginate, 85 parts of sodium lignosulfonate, and 1 part of triethanolamine; the remaining methods are the same as in Example 1. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 6:

[0036] A method for preparing a lithium-ion battery silicon anode binder includes the following steps: Step 1: Dissolve sodium alginate in phosphate buffer solution, adjust pH to 6, then add EDC and NHS, stir, then add polyetheramine, heat to react, and obtain composite sodium alginate; the concentration of phosphate buffer solution is 0.1M; Step 2: Dissolve the composite sodium alginate in deionized water, then add sodium lignosulfonate, porous inorganic filler, and lithium polyacrylate, and continue stirring to obtain a premixed solution; the mass ratio of composite sodium alginate, sodium lignosulfonate, porous inorganic filler, and lithium polyacrylate is 1:5:0.5:1. Step 3: Add triethanolamine to the premixed solution, adjust the pH to 8.0, then add tannic acid solution and citric acid solution, and use deionized water to adjust the solid content of the mixture to 12% to obtain lithium battery silicon anode binder; The compound sodium alginate comprises the following components by weight: 1 part sodium alginate, 100 parts phosphate buffer, 1.8 parts EDC, 2.3 parts NHS, and 1 part polyetheramine; The porous inorganic filler is prepared by the following process: Step (1): Add zinc nitrate and ferric nitrate to 2-methylimidazole, stir, then add DMF, heat to react, after the reaction is complete, centrifuge, dry to obtain MOFs; Step (2): Add graphene oxide to an ethanol solution, disperse, then add MOFs, heat to react, filter after the reaction is complete, calcine at 500℃ for 1 h to obtain porous inorganic filler; the mass ratio of zinc nitrate to 2-methylimidazole is 1:2; the molar ratio of zinc nitrate to ferric nitrate is 1.5:1; the mass ratio of graphene oxide, DMF, and MOFs is 1:20:5; the concentration of the ethanol solution is 70 wt%. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 7:

[0037] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the composite sodium alginate comprises the following components by mass: 1.5 parts sodium alginate, 110 parts phosphate buffer, 1.8 parts EDC, 2.4 parts NHS, and 2 parts polyetheramine. The mass ratio of zinc nitrate to 2-methylimidazole was 1:3; the molar ratio of zinc nitrate to ferric nitrate was 2:1; the mass ratio of graphene oxide, DMF, and MOFs was 3:50:20, and the remaining methods were the same as in Example 6. The application of a lithium-ion battery silicon anode binder is the same as in Example 1. Example 8:

[0038] This embodiment provides a method for preparing a lithium-ion battery silicon anode binder, wherein the composite sodium alginate comprises the following components by mass: 2 parts sodium alginate, 120 parts phosphate buffer, 2 parts EDC, 2.5 parts NHS, and 3 parts polyetheramine. The mass ratio of zinc nitrate to 2-methylimidazole is 1:5; the molar ratio of zinc nitrate to ferric nitrate is 3:1; the mass ratio of graphene oxide, DMF, and MOFs is 5:100:25, and the remaining methods are the same as in Example 6; the application of a lithium-ion battery silicon anode binder is the same as in Example 1.

[0039] Comparative Example 1: This comparative example provides a lithium-ion battery silicon anode binder prepared from CMC (sodium carboxymethyl cellulose), SBR (styrene-butadiene rubber), and deionized water. The mass ratio of CMC to SBR is 9:1, and the solid content of the mixture is 10%. The application of the lithium-ion battery silicon anode binder is the same as in Example 1.

[0040] Comparative Example 2: This comparative example provides a method for preparing a lithium-ion battery silicon anode binder, in which sodium carboxymethyl cellulose is replaced with sodium alginate, and the rest of the method is the same as in Example 1; the application of the lithium-ion battery silicon anode binder is the same as in Example 1.

[0041] Comparative Example 3: This comparative example provides a method for preparing a lithium-ion battery silicon anode binder without adding porous inorganic fillers; the remaining methods are the same as in Example 6; the application of the lithium-ion battery silicon anode binder is the same as in Example 1.

[0042] Comparative Example 4: This comparative example provides a method for preparing a lithium-ion battery silicon anode binder, in which graphene oxide is replaced with a porous inorganic filler, and the rest of the method is the same as in Example 6; the application of the lithium-ion battery silicon anode binder is the same as in Example 1.

[0043] experiment:

[0044] The lithium-ion battery silicon anode binders obtained in Examples 1-8 and Comparative Examples 1-4 were used to prepare samples, and their performance was tested and the test results were recorded.

[0045] Electrode peel strength test: Cut silicon electrode sheets into strips with dimensions of 15mm × 120mm, then fix the copper foil side to the stainless steel plate with 3M double-sided tape, and attach 3M transparent tape to the electrode side. Then test the peel strength of the silicon electrode at 180° using an electronic universal testing machine at a speed of 20mm / min; Test tape: 12.7mm wide 3M transparent tape; Electrical performance testing: The cycle performance of the button cell was tested using the Blue Electric Testing System (CT3002A). Before testing, the cell underwent three pre-cycles at a low current density (0.05C), with a voltage range of 0.01~1.2V and a current density of 1C. Long-cycle testing was then completed in a 28℃ constant temperature chamber. The specific capacity was calculated from the cell's capacity and mass. The capacity retention rate was calculated from the initial capacity and the capacity after cycling.

[0046] Performance Comparison Table

[0047] Based on the data in the table above, the following conclusions can be clearly drawn: The lithium-ion battery silicon anode binders obtained in Examples 1-8 were compared with those obtained in Comparative Examples 1-4. The test results show that: A comparison of Examples 1-8 with Comparative Example 1 shows that the lithium-ion battery silicon anode binder of the present invention has excellent bonding strength and electrochemical performance; sodium lignosulfonate provides rigid support and dispersibility, sodium alginate provides flexibility and ion transport channels, tannic acid provides super strong polyphenol hydrogen bond adhesion, and citric acid forms a stable covalent cross-linked network through heat treatment, providing the material with high strength and modulus, forming a high-density dynamic hydrogen bond network, giving the material excellent toughness, effectively buffering stress, avoiding silicon anode cracking, improving the rate and cycle performance of the battery cell, and ensuring the stability of the battery cell during use.

[0048] Comparing Example 1 with Comparative Example 2, the lithium-ion battery silicon anode binder obtained in Comparative Example 2 has low peel strength and poor electrical performance. It can be seen that, although sodium carboxymethyl cellulose and sodium alginate are both natural polysaccharide compounds, the adhesion effect of sodium carboxymethyl cellulose and its compatibility with the silicon anode are not as good as those of this application. This demonstrates the technical advantage of using sodium alginate as a reinforcing phase in this invention.

[0049] Comparing Example 6 with Comparative Example 3, the lithium-ion silicon anode binder obtained in Comparative Example 3 has low peel strength, reduced conductivity, and poor electrical performance. It can be seen that without the addition of porous inorganic fillers, the ion transport channels in the binder are reduced, and the cycle performance of the battery prepared using the binder without the addition of porous inorganic fillers is reduced, which reflects the technical advantage of the present invention of adding porous inorganic fillers.

[0050] Comparing Example 6 with Comparative Example 4, the lithium-ion silicon anode binder obtained in Comparative Example 4 has low peel strength and poor electrical performance. It can be seen that although the layered structure of graphene oxide can promote polymer loading, graphene oxide alone cannot meet the requirements of high capacity and high stability. This demonstrates the technical advantage of the present invention in combining metal-organic frameworks with graphene oxide.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a lithium-ion battery silicon anode binder, characterized in that: Includes the following steps: S1: Add deionized water and sodium alginate to the reaction vessel, stir, then add sodium lignosulfonate, continue stirring, cool, and obtain premixed solution a; S2: Dissolve tannic acid in deionized water to obtain a tannic acid solution; S3: Dissolve citric acid in deionized water to obtain a citric acid solution; S4: Slowly add triethanolamine to premixed solution a to adjust the pH value and obtain premixed solution b; S5: Add tannic acid solution to premixed solution b, stir and react, then add citric acid solution, continue stirring, adjust the solid content of the mixture, and obtain lithium battery silicon anode binder.

2. The method for preparing a lithium-ion battery silicon anode binder according to claim 1, characterized in that: The lithium-ion battery silicon anode binder comprises the following components by weight: 10-25 parts of tannic acid, 10-20 parts of citric acid, 10-20 parts of sodium alginate, 70-90 parts of sodium lignosulfonate, and 0.9-1 parts of triethanolamine.

3. The method for preparing a lithium-ion battery silicon anode binder according to claim 1, characterized in that: The solid content of the mixture is 10-15%.

4. The method for preparing a lithium-ion battery silicon anode binder according to claim 1, characterized in that: The specific steps of step S5 are as follows: maintain the stirring speed of premixed solution b at 150~200 rpm, add tannic acid solution within 20~30 min, increase the stirring speed to 250~300 rpm, react for 15~30 min, add citric acid solution within 20~40 min, continue stirring for 30~60 min, use deionized water to adjust the solid content of the solution, and obtain lithium battery silicon anode binder.

5. The method for preparing a lithium-ion battery silicon anode binder according to claim 1, characterized in that: In step S4, adjust the pH value to 8.0~9.

0.

6. The method for preparing a lithium-ion battery silicon anode binder according to claim 1, characterized in that: The lithium-ion battery silicon anode binder can also be prepared by the following process: Step 1: Dissolve sodium alginate in phosphate buffer solution, adjust the pH to 6-7.2, then add EDC and NHS, stir, then add polyetheramine, heat to react, and obtain composite sodium alginate; Step 2: Dissolve the composite sodium alginate in deionized water, then add sodium lignosulfonate, porous inorganic filler, and lithium polyacrylate, and continue stirring to obtain a premixed solution; Step 3: Add triethanolamine to the premixed solution, adjust the pH to 8.0~9.0, then add tannic acid solution and citric acid solution, and use deionized water to adjust the solid content of the solution to obtain lithium battery silicon anode binder.

7. The method for preparing a lithium-ion battery silicon anode binder according to claim 6, characterized in that: The composite sodium alginate comprises the following components by weight: 1-2 parts sodium alginate, 100-120 parts phosphate buffer, 1.8-2 parts EDC, 2.3-2.5 parts NHS, and 1-3 parts polyetheramine.

8. The method for preparing a lithium-ion battery silicon anode binder according to claim 6, characterized in that: The porous inorganic filler is prepared by the following process: Step (1): Add zinc nitrate and ferric nitrate to 2-methylimidazole, stir, then add N,N-dimethylformamide, heat to react, after the reaction is complete, centrifuge, dry to obtain MOFs; Step (2): Add graphene oxide to an ethanol solution, disperse it, then add MOFs, heat to react, filter and calcine after the reaction is complete to obtain porous inorganic filler.

9. The method for preparing a lithium-ion battery silicon anode binder according to claim 8, characterized in that: The mass ratio of zinc nitrate to 2-methylimidazole is 1:(2~5); the molar ratio of zinc nitrate to ferric nitrate is (1.5~3):

1.

10. The method for preparing a lithium-ion battery silicon anode binder according to claim 8, characterized in that: The mass ratio of graphene oxide, N,N-dimethylformamide, and MOFs is (1~5):(20~100):(5~25).

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