Lithium battery aqueous binder and preparation method therefor

Abstract

The present application relates to the technical field of lithium-ion battery materials, and discloses a lithium battery aqueous binder and a preparation method therefor. The binder is obtained by copolymerizing 20% to 40% by weight of a polar monomer, 59.5% to 79.5% by weight of a non-polar monomer, and 0.1% to 0.7% by weight of a crosslinking monomer; and the glass transition temperature of the binder is -9.2°C to 58.8°C. The preparation method comprises: (1) adding a polar monomer, a non-polar monomer, a crosslinking monomer, an emulsifier, and deionized water to a reaction vessel, and stirring and mixing same uniformly to obtain a mixed solution; and (2) after nitrogen is deoxygenated, heating the mixed solution to a reaction temperature of 50°C to 90°C, adding an initiator dropwise to carry out a reaction, cooling after the reaction is completed, and adding an alkaline solution to neutralize to a pH of 6-8 to obtain a product. The aqueous binder of the present application can completely replace conventional carboxymethyl cellulose and styrene-butadiene latex, and has the advantages of high cost-effectiveness, environmental friendliness, and good bonding performance and electrical performance.

Description

A water-based binder for lithium batteries and its preparation method

[0001] This application claims priority to Chinese Patent Application No. 202411597258.4, filed on November 11, 2024, entitled "An Aqueous Binder for Lithium Batteries and Its Preparation Method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of lithium-ion battery material technology, specifically relating to an aqueous binder for lithium batteries and its preparation method. Background Technology

[0003] Lithium-ion batteries, as high-performance, high-energy-density batteries, are widely used in electric vehicles, portable devices, and energy storage systems. The preparation process of the negative electrode material has a significant impact on battery performance. Currently, commonly used lithium-ion battery negative electrodes mainly consist of negative electrode active materials, conductive additives, binders, and current collectors. The binder is a crucial component of the lithium-ion battery negative electrode. It tightly adheres the active material and conductive agent to the current collector, forming a complete electrode and preventing the active material from detaching or peeling off during charging and discharging. Simultaneously, the binder uniformly disperses the active material and conductive agent, thereby forming a good electron and ion transport network, achieving efficient electron and lithium-ion transport, and ensuring the structural stability and electrochemical performance of the battery negative electrode.

[0004] Traditional binders primarily use carboxymethyl cellulose (CMC) and styrene-butadiene latex (SBR). However, using CMC and SBR as binders for lithium-ion battery anodes has several drawbacks. Their application process is relatively complex. They need to be added in batches during battery manufacturing, which not only increases production steps but can also lead to uneven material distribution, affecting overall battery performance. Furthermore, this batch addition method may reduce production line efficiency and increase production costs. Secondly, CMC and SBR, as binders, have inherent limitations in performance; their bonding strength is relatively low, which may cause active materials inside the battery to detach during charge and discharge, affecting cycle life and safety. In addition, both materials perform poorly at low temperatures, limiting the application of lithium-ion batteries in cold regions.

[0005] Novel adhesives mainly include polyurethane, polyether, polyester, and polyacrylate, among which polyacrylate adhesives are widely used due to their good adhesion and high-temperature resistance. However, conventional polyacrylate adhesives generally have high glass transition temperatures (above 60°C), and their low-temperature discharge performance needs further improvement. Furthermore, their low flexibility during high-speed coating and cell winding processes in industrial production easily leads to cracking, affecting electrode performance and production efficiency. Summary of the Invention

[0006] To address the shortcomings of existing lithium battery binders, the primary objective of this application is to provide a novel aqueous binder for lithium batteries. The aqueous binder provided in this application is a novel polyacrylic acid (PAA) lithium battery binder that can completely replace traditional carboxymethyl cellulose and styrene-butadiene emulsions. Compared to traditional carboxymethyl cellulose and styrene-butadiene emulsions, the PAA binder provided in this application simplifies the production process while improving bonding performance and low-temperature performance. Through innovative chemical formulation and process design, the novel binder can be added in a single step, reducing production steps and improving production efficiency. Simultaneously, the novel binder will exhibit higher bonding strength and better low-temperature stability, thereby enhancing the overall performance and reliability of lithium batteries. Using the binder provided in this application will contribute to the development of lithium battery technology and meet the ever-increasing demand for energy storage.

[0007] Another objective of this application is to provide a method for preparing the aforementioned aqueous binder for lithium batteries.

[0008] This application is achieved through the following technical solution:

[0009] A lithium battery aqueous binder is obtained by copolymerization of 20%–40% polar monomers, 59.5%–79.5% non-polar monomers and 0.1%–0.7% crosslinking monomers by weight; the glass transition temperature (Tg) of the lithium battery aqueous binder is -9.2–58.8℃.

[0010] Preferably, the lithium battery aqueous binder is obtained by copolymerization of 20% to 30% by weight of polar monomers, 69.5% to 79.5% by weight of non-polar monomers and 0.3% to 0.5% by weight of crosslinking monomers; the glass transition temperature of the lithium battery aqueous binder is -9.2 to 49.6°C.

[0011] In the binder of this application, polar monomers mainly provide adhesion, non-polar monomers regulate and lower the glass transition temperature (Tg) of the polymer, and crosslinking monomers provide cohesion to the polymer. Through the combination of the above-mentioned polymeric monomers, the resulting binder exhibits strong adhesion to the negative electrode sheet of lithium batteries, while also possessing good flexibility, making it suitable for high-speed coating and cell winding processes in industrial production, thereby improving production efficiency. Further, the polar monomer is at least one selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylonitrile, methacrylonitrile, 2-acetoxyacrylonitrile, 3-methoxyacrylonitrile, 3-(benzenesulfonyl)acrylonitrile, acrylamide, methacrylamide, hydroxymethylacrylonitrile, vinyl acetate, vinyl propionate, vinyl butyrate, N-vinylpyrrolidone, vinylpyridine, vinylimidazole, sodium p-styrenesulfonate, potassium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and allyl polyether.

[0012] Further, the nonpolar monomer is at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N,N-diallyldodecylamine, octadecyl polyethylene glycol acrylate, octadecyl polyethylene glycol methacrylate, methoxyacrylate polyethylene glycol ester, vinyl methacrylate, alkoxyphenol acrylate, and isodecyl methacrylate.

[0013] Further, the crosslinking monomer is at least one selected from divinylbenzene, diallyl phthalate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexamethacrylate, divinyl ethylene glycol, diallyl itaconic acid, diallyl maleate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and bisphenol A dimethacrylate.

[0014] Furthermore, the weight-average molecular weight of the lithium battery aqueous binder is 10W to 50W. That is, the weight-average molecular weight of the lithium battery aqueous binder is 100,000 to 500,000.

[0015] The preparation method of the above-mentioned aqueous binder for lithium batteries includes the following preparation steps:

[0016] (1) Add polar monomer, nonpolar monomer, crosslinking monomer, emulsifier and deionized water to the reaction vessel and stir to mix well to obtain a mixture;

[0017] (2) After nitrogen deoxygenation, the mixture is heated to the reaction temperature of 50-90°C, and an initiator is added dropwise to carry out the reaction. After the reaction is completed, the temperature is lowered to room temperature, and an alkaline solution is added to neutralize the pH to 6-8, thus obtaining the lithium battery aqueous binder.

[0018] Further, the emulsifier is one or more of anionic emulsifiers, nonionic emulsifiers, and reactive emulsifiers; the anionic emulsifier includes, but is not limited to, higher alcohol sulfate salts, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, and sulfate salts of nonionic surfactants; the nonionic emulsifier includes, but is not limited to, polyethylene glycol alkyl esters, alkylphenyl ethers, and alkyl ethers; the reactive emulsifier includes, but is not limited to, sodium methyl allyl sulfonate, sodium allyl sulfonate, and sodium p-styrene sulfonate. In this application, there is no particular limitation on the amount of emulsifier used, as long as it achieves the purpose of this application. For example, the ratio of the mass of the emulsifier to the total mass of the polar monomer, nonpolar monomer, and crosslinking monomer is (0.01–0.05):1. For example, the ratio of the mass of the emulsifier to the total mass of the polar monomers, non-polar monomers, and crosslinking monomers can be 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, or a range of any two of these values.

[0019] Further, the initiator is a free radical polymerization initiator, which includes water-soluble polymerization initiators and redox polymerization initiators; the water-soluble polymerization initiators include, but are not limited to, potassium persulfate, sodium persulfate, and ammonium persulfate; the redox polymerization initiators include oxidants and reductants, the oxidants include, but are not limited to, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, tert-butyl hydroperoxide, acetyl peroxide, and dicumyl hydroperoxide, and the reductants include, but are not limited to, isoascorbic acid, ferrous ions, sodium sulfite, and sodium bisulfite. In this application, there is no particular limitation on the amount of initiator used, as long as the purpose of this application is achieved. For example, the ratio of the mass of the initiator to the total mass of the polar monomer, non-polar monomer, and crosslinking monomer is (0.0005–0.004):1. For example, the ratio of the mass of the initiator to the total mass of the polar monomer, non-polar monomer, and crosslinking monomer can be 0.0005:1, 0.001:1, 0.002:1, 0.003:1, 0.004:1, or a range of any two of these values.

[0020] Furthermore, the reaction time is 0.5 to 6 hours.

[0021] Furthermore, the alkaline solution is a lithium hydroxide or sodium hydroxide solution.

[0022] Compared with the prior art, the beneficial effects of this application are:

[0023] (1) The aqueous binder of this application has a low glass transition temperature (Tg of -9.2 to 58.8°C), resulting in flexible electrodes that are suitable for high-speed coating and cell winding processes in industrial production, thus improving production efficiency. (During lithium-ion battery electrode coating and cell winding processes, the temperature of the battery cell is generally below 60°C. When the glass transition temperature of the binder is lower than the processing temperature, the binder has better fluidity, making it easier to coat and penetrate, thereby improving processing efficiency and bonding effect. However, if the glass transition temperature of the binder is too low compared to the processing temperature, it will cause the binder to soften excessively or even leak, which will also reduce the bonding effect and increase losses. The glass transition temperature range of the aqueous binder of this application can better match the ambient temperature (-10 to 60°C) during the lithium-ion battery electrode coating and cell winding processes. At the same time, the prepared lithium-ion battery has better low-temperature discharge performance.)

[0024] (2) The aqueous binder of this application can completely replace carboxymethyl cellulose and styrene-butadiene emulsion, and has better adhesion to the negative electrode sheet of lithium battery. It can achieve better adhesion effect with less binder addition; at the same time, it can improve the electrode energy density while reducing the amount of binder used. Attached Figure Description

[0025] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0026] Figure 1 shows the low-temperature discharge curves of the lithium-ion batteries assembled with the binder in Example 6 and Comparative Example 1. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0028] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0029] Examples 1-13

[0030] Examples 1-13 describe an aqueous binder for lithium batteries. The composition of the reactive monomers is shown in Table 1. The preparation method of the binder includes the following steps: Emulsifier (0.5g sodium dodecyl sulfate, 2g sodium p-styrene sulfonate), all reactive monomers (total mass of all reactive monomers is 100g), and 300g deionized water are added to a 1L five-necked flask. Stirring is initiated at 250 rpm, nitrogen is introduced for 1 hour, and the temperature is raised to 65°C. 0.15g ammonium persulfate and 0.1g sodium sulfite dissolved in 5g deionized water are added sequentially to the 1L five-necked flask as initiators. After reacting for 120 minutes, the temperature is raised to 70°C and maintained for 2 hours. The mixture is then cooled to room temperature, neutralized with NaOH solution, and the pH is adjusted to 6-8. The solid content of the product is adjusted to 10% with deionized water to obtain the aqueous binder for lithium batteries.

[0031] Comparative Example 1

[0032] This comparative example provides a lithium battery binder composed of conventional carboxymethyl cellulose and styrene-butadiene emulsion.

[0033] Comparative Example 2

[0034] Except for adjusting the weight percentages of the polar monomer acrylonitrile and acrylamide to 2.5% and the non-polar monomer propyl acrylate to 43.5%, the rest of the composition is the same as in Example 6. That is, in Comparative Example 2, the weight percentages of the polar monomers are 15%, the non-polar monomers are 84.5%, and the crosslinking monomers are 0.5%.

[0035] Comparative Example 3

[0036] Except for adjusting the weight percentages of the polar monomer acrylonitrile and acrylamide to 20% and the non-polar monomer propyl acrylate to 8.5%, the rest of the composition is the same as in Example 6. That is, in Comparative Example 3, the weight percentages of the polar monomers are 50%, the non-polar monomers are 49.5%, and the crosslinking monomers are 0.5%. The physicochemical properties and application performance test methods of the adhesives obtained in the above examples and comparative examples are as follows:

[0037] I. Molecular weight test of adhesive:

[0038] The weight-average molecular weight of the adhesive was determined using gel permeation chromatography (GPC). After drying the adhesive in an oven at 35°C, impurities were removed using tetrahydrofuran, and the GPC test was performed. The sample retention time was 60–1600 s.

[0039] II. Glass transition temperature (Tg) test of adhesive:

[0040] The glass transition temperature (Tg, °C) of the adhesive was tested using dynamic thermomechanical analysis (DMA). The adhesive was dried in an oven at 35 °C and then cut into strips of 5 mm × 200 mm. The DMA test temperature range was -10 to 150 °C.

[0041] III. Application Performance Testing:

[0042] The binders synthesized in Examples 1-13, Comparative Examples 2 and 3 were mixed with active materials graphite and conductive carbon, respectively, to prepare electrode sheets, which were then assembled into pouch cells. The specific methods are as follows:

[0043] The formula and weight ratio are: graphite: conductive carbon: binder = 96:1.5:2.5.

[0044] Deionized water was added to a mixing tank, along with the binder and conductive carbon synthesized in the above embodiment. The mixture was dispersed at high speed of 1500 rpm for 2 hours. Graphite was then added, and the mixture was dispersed at high speed for another 2 hours. After the fineness of the negative electrode slurry was tested and found to be qualified, the mixture was adjusted to low speed of 500 rpm and vacuum defoamed for 30 minutes. The mixture was then coated onto copper foil and dried to obtain the lithium-ion battery negative electrode sheet.

[0045] The formulation combination used in Comparative Example 1 was: graphite: conductive carbon: carboxymethyl cellulose: styrene-butadiene emulsion = 95:1.5:1.5:2.

[0046] Deionized water was added to a mixing tank, carboxymethyl cellulose was added and dissolved, then conductive carbon was added, and the mixture was dispersed at high speed of 1500 rpm for 2 hours. Graphite was added, and the mixture was dispersed at high speed for another 2 hours. After the fineness of the negative electrode slurry was tested and found to be qualified, the mixture was adjusted to low speed of 500 rpm and stirred. Styrene-butadiene emulsion was added, and after defoaming for 30 minutes, the mixture was coated onto copper foil and dried to obtain the negative electrode sheet for lithium-ion batteries.

[0047] The areal density of the negative electrode in the above tests was 250 g / m³. 2 The compacted density is 1.6 g / cc.

[0048] A soft-pack lithium-ion battery was assembled using the above-mentioned negative and positive electrode sheets and subjected to constant current charge-discharge testing. The positive electrode sheet used was S85E, with NCM:SP:PVDF = 96.8:2:1.2 and a positive electrode areal density of 400 g / m³. 2 The positive electrode compaction density is 3.4 g / cc. The electrolyte used is Tinci Materials electrolyte, grade TC-E8630N3. The charging termination voltage is 2.7~4.2V, the charge / discharge rate is 1C, and the cut-off current is 100mA.

[0049] Peel strength test method: The negative electrode sheets of the examples and comparative examples were tested for 180° peel force using a universal tensile tester. The peel force test was conducted using a sample made of 2cm wide and 5cm long. The pulling speed was 2mm / s. The unit of peel force is N / m.

[0050] The monomer composition of Examples 1-13 and the molecular weight, Tg, and peel strength test results of the resulting adhesives are shown in Table 1 below. The molecular weight, Tg, and peel strength test results of the adhesives obtained in Comparative Examples 2 and 3 are shown in Table 2 below.

[0051] Table 1

[0052] Note: In Table 1, " / " indicates that there are no relevant preparation parameters.

[0053] Table 2

[0054] The comparison results of Examples 6, 9, and 10 in Table 1 show that the glass transition temperature of the resulting adhesive gradually decreases with the increase of non-polar monomer content. The comparison results of Examples 1-4 and Examples 5-8 show that the choice of acrylate in the non-polar monomer has a significant impact on the glass transition temperature of the adhesive, with isooctyl acrylate having the greatest effect on reducing the glass transition temperature of the adhesive, followed by butyl acrylate, then propyl acrylate, and finally ethyl acrylate. Furthermore, the results of Examples 6 and 11-13 show that the crosslinking agent content also has a significant impact on the glass transition temperature and peel strength of the adhesive. When the crosslinking agent content is too high, the crosslinking density of the resulting adhesive is too high, leading to a significant increase in the glass transition temperature. When the crosslinking agent content is too low, the cohesion of the resulting adhesive is low, resulting in a significant decrease in bonding performance. This application describes an aqueous binder obtained by copolymerizing 20%–40% polar monomers, 59.5%–79.5% non-polar monomers, and 0.1%–0.7% crosslinking monomers. The binder exhibits a glass transition temperature (Tg) ranging from -9.2 to 58.8°C. This binder is suitable for high-speed coating and cell winding processes in industrial production, improving production efficiency. It also possesses excellent adhesion properties. Preferably, when the polar monomer content ranges from 20%–30%, the non-polar monomer content ranges from 69.5%–79.5%, and the crosslinking monomer content ranges from 0.3%–0.5%, the resulting aqueous binder has a Tg < 50°C, and the electrode peel strength > 13 N / m.

[0055] The peel strength of the negative electrode sheets prepared by the binder in Example 6 and Comparative Example 1, as well as the first discharge efficiency and -20℃ 0.5C discharge efficiency of the assembled lithium-ion batteries, are shown in Table 3 below. Their low-temperature discharge curves are shown in Figure 1.

[0056] Table 3

[0057] The results above show that the lithium battery binder prepared in this application has better bonding performance and low-temperature discharge performance compared with conventional carboxymethyl cellulose and styrene-butadiene emulsion binders.

[0058] The above embodiments are preferred embodiments of this application, but the implementation of this application is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this application shall be considered equivalent substitutions and shall be included within the protection scope of this application.

Claims

1. A water-based binder for lithium batteries, which is obtained by copolymerization of 20% to 40% by weight of polar monomers, 59.5% to 79.5% by weight of non-polar monomers and 0.1% to 0.7% by weight of crosslinking monomers; wherein the glass transition temperature of the water-based binder for lithium batteries is -9.2 to 58.8°C.

2. The aqueous binder for lithium batteries according to claim 1, wherein, The aqueous binder for lithium batteries is obtained by copolymerization of 20%–30% polar monomers, 69.5%–79.5% non-polar monomers and 0.3%–0.5% crosslinking monomers by weight; the glass transition temperature of the aqueous binder for lithium batteries is -9.2 to 49.6°C.

3. The aqueous binder for lithium batteries according to claim 1, wherein, The polar monomer is at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylonitrile, methacrylonitrile, 2-acetoxyacrylonitrile, 3-methoxyacrylonitrile, 3-(benzenesulfonyl)acrylonitrile, acrylamide, methacrylamide, hydroxymethylacrylamide, vinyl acetate, vinyl propionate, vinyl butyrate, N-vinylpyrrolidone, vinylpyridine, vinylimidazolium, sodium p-styrenesulfonate, potassium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and allyl polyether.

4. The aqueous binder for lithium batteries according to claim 1, wherein, The nonpolar monomer is at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N,N-diallyldodecylamine, octadecyl polyethylene glycol acrylate, octadecyl polyethylene glycol methacrylate, methoxyacrylate polyethylene glycol ester, vinyl methacrylate, alkoxyphenol acrylate, and isodecyl methacrylate.

5. The aqueous binder for lithium batteries according to claim 1, wherein, The crosslinking monomer is at least one of divinylbenzene, diallyl phthalate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexamethacrylate, divinyl ethylene glycol, diallyl itaconic acid, diallyl maleate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and bisphenol A dimethacrylate.

6. A lithium battery aqueous binder according to any one of claims 1 to 5, wherein, The weight-average molecular weight of the lithium battery aqueous binder is 10W to 50W.

7. A method for preparing an aqueous binder for lithium batteries according to any one of claims 1 to 6, comprising the following preparation steps: (1) Add polar monomer, non-polar monomer, crosslinking monomer, emulsifier and deionized water to the reaction vessel and stir to mix well to obtain a mixture; (2) After nitrogen deoxygenation, the mixture is heated to the reaction temperature of 50-90°C, and an initiator is added dropwise to carry out the reaction. After the reaction is completed, the temperature is lowered to room temperature, and an alkaline solution is added to neutralize the pH to 6-8, thus obtaining the lithium battery aqueous binder.

8. The method for preparing an aqueous binder for lithium batteries according to claim 7, wherein, The emulsifier is one or more of anionic emulsifiers, nonionic emulsifiers, and reactive emulsifiers; the anionic emulsifier includes at least one of higher alcohol sulfate salts, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, and sulfate salts of nonionic surfactants; the nonionic emulsifier includes at least one of polyethylene glycol alkyl esters, alkylphenyl ethers, and alkyl ethers; the reactive emulsifier includes at least one of sodium methyl allyl sulfonate, sodium allyl sulfonate, and sodium p-styrene sulfonate.

9. The method for preparing an aqueous binder for lithium batteries according to claim 7, wherein, The initiator is a free radical polymerization initiator, which includes water-soluble polymerization initiators and redox polymerization initiators. The water-soluble polymerization initiator includes at least one of potassium persulfate, sodium persulfate, and ammonium persulfate. The redox polymerization initiator includes an oxidant and a reducing agent. The oxidant includes at least one of potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, tert-butyl hydroperoxide, acetyl peroxide, and dicumyl hydroperoxide. The reducing agent includes at least one of isoascorbic acid, ferrous ion salts, sodium sulfite, and sodium bisulfite.

10. The method for preparing an aqueous binder for lithium batteries according to claim 7, wherein, The reaction time is 0.5 to 6 hours; the alkaline solution is lithium hydroxide or sodium hydroxide solution.

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