Aqueous composite binder for silicon-carbon anodes for lithium-ion batteries, method of preparation and battery comprising the same

Abstract

The present application belongs to the technical field of lithium ion batteries, and specifically relates to a water-based composite binder for a silicon-carbon negative electrode of a lithium ion battery, a preparation method and a battery containing the binder. The water-based composite binder comprises three components: the first component is a guanidine bond-containing compound and its salt; the second component is a chain derivative of glutamic acid; and the third component is a derivative of polystyrene. The composite binder obtained is suitable for a silicon-carbon negative electrode of a lithium ion battery, and can improve the cycle stability and rate performance. The chain derivative containing a guanidine bond and the chain derivative of glutamic acid are associated by hydrogen bonds, and a soft chain that induces a solid-state electrolyte interface with strong and rich polarity functional groups and buffer volume expansion is constructed. At the same time, the hard chain polystyrene derivative containing a benzene ring provides strong binding to the composite binder. The soft chain and the hard chain act simultaneously, and the silicon-carbon negative electrode is wrapped, greatly buffering the volume expansion. The water-based composite binder of the present application is simple and convenient to prepare, and the raw materials are economical. Deionized water is used as a solvent, which is green and environmentally friendly. The use of the water-based composite binder can effectively improve the processability of the silicon-carbon negative electrode of the lithium ion battery and improve the electrochemical performance, and has a good commercial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an aqueous composite binder for silicon-carbon anodes of lithium-ion batteries, a preparation method thereof, and a battery containing the binder. Background Technology

[0002] Lithium-ion batteries, with their high energy density, long lifespan, and good low-temperature performance, are considered one of the most promising next-generation high-energy storage systems. Electrode materials, as a key component of lithium-ion storage, determine the battery's cycle stability and energy density. Generally, lithium-ion battery electrode materials mainly consist of four parts: active materials, binders, conductive agents, and current collectors. Although binders account for a very small proportion of the overall electrode system, they play a crucial role in improving the battery's electrochemical performance. The main function of the binder is to connect the active material, conductive agent, and current collector of the electrode, maintaining the integrity of the electrode structure. Excellent binders promote improvements in the battery's discharge platform and high-current discharge capability, reduce internal resistance during low-rate charging, and enhance the battery's fast-charging capability. Silicon-carbon materials, due to their high charging capacity, high safety, and low cost, have become one of the most commercially promising anode materials. However, they face challenges such as large volume expansion during charging and discharging, instability at the electrode / electrolyte interface caused by electrode breakage, and poor cycle performance, which restrict the large-scale commercial application of silicon-carbon anode materials. In addition, silicon-carbon materials have poor hydrophilicity, making them difficult to disperse evenly in water, and they also have poor processing performance.

[0003] Currently, the most commonly used electrode binders are oil-based polyvinylidene fluoride (PVDF) and water-based carboxymethyl cellulose (CMC). PVDF, as an oil-based binder, requires N-methylpyrrolidone (NMP), a toxic and expensive organic solvent, which is detrimental to environmental protection and production cost control. Furthermore, the HF bonds primarily found in PVDF are inactive and therefore cannot provide sufficient force to connect electrode materials, negatively impacting the long-cycle stability of the battery. CMC, as the most commonly used water-based composite binder, contains a large number of polar functional groups, providing good fixation for electrode materials. However, it is brittle, and the prepared silicon-carbon electrodes are prone to powdering and flaking, hindering long-term electrode operation. Additionally, its ionic conductivity needs improvement.

[0004] Patent CN 106992299 A discloses an aqueous binder, which is one or more of polyglutamic acid and / or its derivatives, and may also be cellulose derivatives, sodium alginate derivatives, and polymer derivatives. Compared with organic solvent-based binders (PVDF), this aqueous binder releases no organic solvents and has the characteristics of being non-toxic, low-cost, non-flammable, and safe to use, making it an important development direction for lithium-ion battery binders. However, the patent has a problem: both components are long-chain compounds with low mechanical strength, and when its main component, polyglutamic acid, is used as a binder, it is more likely to form intramolecular hydrogen bonds rather than intermolecular bonds, making it difficult for the two components to produce a synergistic effect and to form a stable SEI. SEI is the most important factor in suppressing the expansion of silicon-based anodes. Therefore, it is very important to develop a new type of high-performance aqueous composite binder to address the problems of the commonly used binders mentioned above. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing lithium-ion battery binders, this invention proposes an aqueous composite binder for silicon-carbon anodes in lithium-ion batteries, a preparation method thereof, and a battery containing the binder. Applying this aqueous composite binder to the silicon-carbon anode of lithium-ion batteries effectively improves the cycle stability and rate performance of the battery.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] This invention discloses an aqueous composite binder for silicon-carbon anodes in lithium-ion batteries. The aqueous composite binder comprises three components: a first component, a second component, and a third component. The first component is one or more of a guanidine-containing compound or its salt as shown in Formula 1; the second component is one or two glutamic acid chain derivatives; and the third component is a polystyrene derivative.

[0008]

[0009] In Formula 1, R1 is a straight-chain or branched alkyl or alkoxy group with 1 to 10 atoms; R2 is -NH2, -COOH, -SO2-Ph-CH3, ... R3 can be any one of -CH3 and -H; R3 can be any one of -NH2, -COOH and -H.

[0010] Preferably, the guanidine-containing compound is N-p-toluenesulfonyl-L-arginine or Nα-benzoyl-L-arginine; the salt of the guanidine-containing compound is L-arginine-L-pyroglutamate; and the glutamate chain derivative is one or two of L-glutamate polymer, N-(4-carbamoyl)-L-glutamate, and L-γ-carboxyglutamate.

[0011] Its structural formula can be expressed as follows:

[0012]

[0013] Preferably, the polystyrene derivative is sodium poly(4-styrenesulfonate), sodium polyanilinesulfonate, or a derivative thereof. Preferably, the first component has a relative molecular mass of 200-500; the L-glutamic acid polymer in the second component has a relative molecular mass of 500,000-700,000, and the remaining compounds have a relative molecular mass of 200-500; the third component has a relative molecular mass of 100,000-300,000.

[0014] Preferably, the first component accounts for 30%-60% of the mass percentage of the water-based composite adhesive; the second component accounts for 20%-40% of the mass percentage of the water-based composite adhesive; and the third component accounts for 20%-40% of the mass percentage of the water-based composite adhesive. The total mass percentage of the three components is 100%.

[0015] This invention also includes a method for preparing the above-mentioned water-based composite adhesive, comprising the following steps:

[0016] (1) Dissolve the first component, the second component, and the third component in deionized water by stirring to obtain a mixed solution;

[0017] (2) The mixed solution is dried to obtain a solid aqueous composite adhesive.

[0018] Preferably, the solvent is deionized water; the total mass ratio of the first component, the second component, and the third component to the volume ratio of deionized water is 0.1 g:(1-4) mL; the stirring temperature is room temperature (20-30℃); and the stirring time is 1-4 h.

[0019] The present invention also includes a silicon-carbon anode for lithium-ion batteries, wherein the silicon-carbon anode for lithium-ion batteries comprises the aqueous composite binder, silicon-carbon anode material and conductive agent.

[0020] Preferably, the conductive agent is any one of acetylene black, Ketjen black, carbon nanotubes, conductive carbon black, and graphene; the silicon-carbon anode material is a commercially available silicon-carbon material. The mass ratio of the silicon-carbon anode material, conductive agent, and aqueous composite binder is (16-19):(1-2):(1-3). The mass ratio of the silicon-carbon anode material, conductive agent, and aqueous composite binder is (80-95):(5-10):(5-15), more preferably 80:10:10.

[0021] A method for preparing a silicon-carbon negative electrode sheet for a lithium-ion battery includes the following steps:

[0022] (1) Preparation of negative electrode slurry: Add conductive agent, silicon-carbon negative electrode material and water-based composite binder of the present invention according to the mass ratio, and then add deionized water and stir to mix evenly to obtain negative electrode slurry;

[0023] (2) Preparation of silicon-carbon negative electrode sheet for lithium-ion battery: The above negative electrode slurry is coated on the current collector and dried at 60-100℃ for 6-10h to obtain silicon-carbon negative electrode sheet for lithium-ion battery.

[0024] The present invention also discloses a lithium-ion battery, wherein the lithium-ion battery includes the silicon-carbon anode of the lithium-ion battery.

[0025] The beneficial effects of this invention are:

[0026] 1. The water-based composite binder provided by this invention comprises: a first component consisting of one or more guanidine chain derivatives; a second component consisting of a glutamic acid chain derivative; and a third component consisting of a polystyrene derivative. Through dissolution and heating reactions, the polar functional groups in the components interact to form hydrogen bonds, resulting in a more stable fibrous polymer rich in polar hydrophilic groups. The guanidine chain derivative first combines with the glutamic acid derivative through hydrogen bonds to form a soft chain, endowing the composite binder with abundant polar amino and imino groups. Simultaneously, it combines with oxygen-containing functional groups on the silicon carbon surface to form hydrogen bonds, encapsulating the silicon carbon surface to form a binder network. The benzene ring-containing hard-chain polystyrene derivative can effectively resist the huge volume expansion of silicon carbon materials during electrochemical reactions. This method of applying both hard and soft chains can buffer the volume expansion of the silicon carbon negative electrode to the greatest extent. At the same time, the guanidine compound, as the main component, can provide ion conduction, and the cation formed after the H on the N of the guanidine double bond leaves has high stability. This unique structural network not only improves the dispersion of carbon materials in water but also enhances the structural stability and ion conduction of silicon carbon materials. This binder results in a smoother surface on the silicon-carbon anode sheet of lithium-ion batteries, reducing excessive electrolyte consumption and corresponding irreversible capacity loss, thus improving the cycle stability of lithium-ion batteries. Simultaneously, the polar groups lower the desolventizing energy barrier, and the amino (-NH2) and carboxyl (-COO-) groups in L-glutamic acid can form coordination bonds with Li ions through sufficient electron donation capabilities, improving the ionic conductivity of the polymer electrolyte and enhancing its kinetic properties.

[0027] 2. The lithium-ion half-cell using the aqueous composite binder of the present invention has a coulombic efficiency of more than 90% in the first cycle, and the specific capacity can still reach 800mAh / g after 100 cycles.

[0028] 3. Lithium-ion batteries using the aqueous composite binder of this invention have a large number of strongly electronegative groups on the surface of the silicon-carbon electrode, which can effectively adsorb lithium ions, reduce the desolventization barrier of lithium ions, accelerate the desolventization process, and reduce the decomposition of organic solvents on the electrode surface, thereby forming a thinner SEI; which helps to maintain the stability of the interface, reduce the interface impedance, and improve the battery's first efficiency, long cycle performance and rate performance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The infrared spectrum of the adhesive in Example 2 is shown.

[0031] Figure 2 Scanning electron microscope (SEM) images of the silicon-carbon anode sheets prepared in Application Example 3 and Comparative Application Examples 1 and 2.

[0032] Figure 3 SEI transmission electron microscope images of the silicon-carbon negative electrode sheets prepared in Application Example 3 and Comparative Application Examples 1 and 2 after the first discharge cycle.

[0033] Figure 4 The first-cycle charge-discharge curves of lithium-ion half-cells prepared using application example 1 and comparative application examples 1 and 2 are shown in the figure.

[0034] Figure 5 The first-cycle charge-discharge curves of lithium-ion half-cells prepared using Application Example 2 and Comparative Application Examples 1 and 2 are shown in the figure.

[0035] Figure 6 The graph shows a comparison of the cycle performance of lithium-ion half-cells prepared using silicon-carbon anode plates from Application Example 2 and Comparative Application Examples 1 and 2.

[0036] Figure 7 The graph shows a comparison of the cycle performance of lithium-ion half-cells prepared using silicon-carbon anode plates from Application Example 3 and Comparative Application Examples 1 and 2. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0038] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known mass units in the chemical industry, such as μg, mg, g, and kg.

[0039] The PVDF used in the embodiments and comparative examples of this invention has a molecular weight of 500,000, the CMC has a molecular weight of 90,000, the average molecular weight of the third component is 100,000-300,000, the L-glutamic acid polymer has a molecular weight of 500,000-700,000, the relative molecular mass of L-arginine-L-pyroglutamic acid salt is 303, the relative molecular mass of N-(4-carbamoyl)-L-glutamic acid is 266, the relative molecular mass of L-γ-carboxyglutamic acid is 191, the relative molecular mass of Na-benzoyl-L-arginine is 278, and the molecular weight of N-p-toluenesulfonyl-L-arginine is 328. All of the above materials were purchased from the Aladdin website.

[0040] Example 1

[0041] This embodiment prepares a water-based composite adhesive comprising 0.02 g of poly(4-styrene sulfonate), 0.02 g of L-glutamic acid polymer, 0.06 g of N-p-toluenesulfonyl-L-arginine, and 2 mL of deionized water. The average molecular weight of the poly(4-styrene sulfonate) is 300,000, and the molecular weight of the L-glutamic acid polymer is 700,000. The preparation steps are as follows:

[0042] (1) Add poly(4-styrene sulfonate), L-glutamic acid polymer and N-p-toluenesulfonyl-L-arginine to a sample bottle, add deionized water to dissolve, stir for 3 hours, and after mixing evenly, a mixed solution rich in polar functional groups is obtained.

[0043] (2) The mixed solution from step (1) is reacted and dried at 80°C to obtain a solid aqueous composite adhesive.

[0044] Example 2

[0045] This embodiment prepares a water-based composite adhesive comprising 0.03 g of sodium polyaniline sulfonate, 0.03 g of N-(4-carbamoyl)-L-glutamic acid, 0.04 g of L-arginine-L-pyroglutamate, and 2 mL of deionized water. The molecular weight of the sodium polyaniline sulfonate is 100,000. The preparation steps are as follows:

[0046] (1) Sodium polyaniline, N-(4-carbamoyl)-L-glutamic acid and L-arginine-L-pyroglutamic acid salt were added to the sample bottle, dissolved in deionized water, stirred for 3 hours, and mixed evenly to obtain a mixed solution rich in polar functional groups.

[0047] (2) The mixed solution from step (1) is reacted and dried at 80°C to obtain a solid aqueous composite adhesive.

[0048] Example 3

[0049] This embodiment prepares a water-based composite adhesive comprising 0.03 g of sodium poly(4-styrene sulfonate), 0.03 g of L-γ-carboxyglutamic acid, 0.04 g of Nα-benzoyl-L-arginine, and 4 mL of deionized water. The average molecular weight of the sodium poly(4-styrene sulfonate) is 200,000. The preparation steps are as follows:

[0050] (1) Add poly(4-styrene sulfonate), L-γ-carboxyglutamic acid and Nα-benzoyl-L-arginine to the sample bottle, add deionized water to dissolve, stir for 3 hours, and after mixing evenly, a mixed solution rich in polar functional groups is obtained.

[0051] (2) The mixed solution from step (1) is reacted and dried at 60°C to obtain a solid aqueous composite adhesive.

[0052] Example 4

[0053] This embodiment prepares a water-based composite adhesive comprising 0.04 g of poly(4-styrene sulfonate), 0.03 g of L-glutamic acid polymer, and 0.03 g of Nα-benzoyl-L-arginine.

[0054] The average molecular weight of poly(sodium 4-styrene sulfonate) is 300,000; the average molecular weight of the L-glutamic acid polymer is 500,000; the preparation steps are as follows:

[0055] (1) Add the poly(4-styrene sulfonate), polyglutamic acid and Nα-benzoyl-L-arginine to a sample bottle, add 4 ml of deionized water to dissolve, stir for 3 h, and after mixing evenly, a mixed solution rich in polar functional groups is obtained.

[0056] (2) The mixed solution from step (1) is dried at 60°C to obtain a solid aqueous composite adhesive.

[0057] Application Examples 1-3

[0058] The aqueous composite binder solid, solvent water, and different electrode materials and conductive agents prepared the silicon-carbon negative electrode sheet for lithium-ion batteries respectively, corresponding to application examples 1-3. The method is as follows: the electrode material (silicon-carbon negative electrode material), conductive agent and binder are weighed and mixed evenly in a mass ratio of 8:1:1, and then deionized water is added and stirred evenly to prepare the battery electrode slurry; the battery electrode slurry is evenly coated on the current collector copper foil with a scraper and dried at 80°C for 8 hours in a forced-air drying oven to obtain the silicon-carbon negative electrode sheet for lithium-ion batteries.

[0059] The specific types and formulations of electrode materials, conductive agents, and water-based composite binders used are shown in Table 1.

[0060] Table 1. Materials and proportions used in silicon-carbon anode sheets for application examples 1-3 of lithium-ion batteries.

[0061]

[0062] Comparative Application Example 1

[0063] The method for preparing silicon-carbon anode sheets for lithium-ion batteries using PVDF as a binder, along with different solvents, electrode materials (silicon-carbon anode materials), and conductive agents is as follows: Electrode materials, conductive agents, and binders are weighed and mixed evenly in a mass ratio of 8:1:1. Then, NMP is added and stirred until evenly mixed to form a battery electrode slurry. The battery electrode slurry is evenly coated onto the current collector copper foil using a scraper and dried in a forced-air drying oven at 80°C for 8 hours to obtain the silicon-carbon anode sheet for lithium-ion batteries.

[0064] Comparative Application Example 2

[0065] The method for preparing silicon-carbon anode sheets for lithium-ion batteries using CMC as a binder, along with different solvents, electrode materials (silicon-carbon anode materials), and conductive agents is as follows: Electrode materials, conductive agents, and binders are weighed and mixed evenly in a mass ratio of 8:1:1. Then, deionized water is added and stirred until evenly mixed to form a battery electrode slurry. The battery electrode slurry is then evenly coated onto a current collector copper foil using a scraper and dried in a forced-air drying oven at 80°C for 8 hours to obtain the silicon-carbon anode sheet for lithium-ion batteries.

[0066] The types and formulations of conductive agents and water-based composite adhesives are shown in Table 2.

[0067] Table 2 compares the materials and proportions used in the silicon-carbon anode sheets of lithium-ion batteries in application examples 1-2.

[0068]

[0069] Implementation Results Example

[0070] (1) The silicon-carbon negative electrode sheets of lithium-ion batteries in Application Examples 1-3 and Comparative Application Examples 1-2 were used to assemble coin cells. The method is as follows: The silicon-carbon negative electrode sheets were stamped into small circular pieces with a diameter of 13 mm. Then, the electrode sheets, separators, electrolytes, lithium sheets, spring sheets and gaskets were sealed in a glove box filled with argon gas to obtain 2025 coin cells. The electrolyte was a commercial silicon-carbon negative electrode electrolyte purchased from Duoduo Reagent Network.

[0071] The cycle stability and rate performance of each lithium-ion half-cell were tested using the constant current method. The potential window was 0.01-1.5V for silicon-carbon anode materials, and the current density was 360mA / g. The test results are shown in Table 3.

[0072] Table 3. Performance test results of lithium-ion half-cells in Application Examples 1-3 and Comparative Application Example 1-2.

[0073]

[0074] As can be seen from the data in Table 3, the lithium-ion half-cells using the aqueous composite binder of the present invention in Application Examples 1-3 generally have high cycle stability, and the specific capacity after a certain number of cycles is improved compared with the lithium-ion half-cells in Application Examples 1 and 2. This indicates that the aqueous composite binder prepared by the present invention can be well applied to the silicon-carbon anode of lithium-ion batteries and plays an important role in improving the performance of lithium-ion batteries.

[0075] Figure 1 The infrared spectrum of the aqueous composite binder in Example 2 shows intramolecular hydrogen bonds at 3587 and 3362 cm⁻¹; and at 2920, 2362, 1647, 1408, and 1160 cm⁻¹. -1 The characteristic peaks belong to -NH, CN and C=O, -OH, -COC bonds, respectively, which confirms the presence of multiple polar functional groups in this aqueous composite binder, and the 3500 cm⁻¹ peaks indicate that this binder has a variety of polar functional groups. -1 The shifted peaks to the left and right correspond to the formation of hydrogen bonds between the carboxyl groups in the glutamic acid derivative and the amino groups in the guanidine-containing derivative, while also combining with the oxygen functional groups on the silicon carbon surface, improving their dispersion, which helps to smooth the electrode and enhance the adhesion to the electrode.

[0076] Figure 2 The images show scanning electron microscope (SEM) images of the silicon-carbon negative electrode sheets of Application Example 3 and Comparative Application Examples 1 and 2. As can be seen from the images, there is obvious fibrous binder on the surface of the silicon-carbon negative electrode sheet of Application Example 3, indicating that the binder and silicon-carbon are mixed more uniformly, and the adhesion between the materials is tighter than that of Comparative Application Examples 1 and 2. This can reduce the contact between defects on the electrode and the electrolyte, thereby reducing excessive consumption of electrolyte and helping to improve the cycle stability of the battery.

[0077] Figure 3 The transmission electron microscopy (TEM) images of the solid electrolyte interphase (SEI) membranes of the silicon-carbon anode plates in Application Example 3 and Comparative Application Examples 1 and 2 after the first discharge cycle show that the aqueous composite binder of this invention induces a thinner SEI (92 nm) on the electrode surface, compared to the thicker SEI in Application Examples 1 and 2. A thinner SEI indicates less electrolyte consumption on the electrode surface, and the uniform interface helps improve the lithium-ion transport rate, thereby improving its kinetic characteristics and cycle stability. Conversely, a thicker SEI indicates excessive electrolyte consumption, which is detrimental to rapid lithium-ion transport, makes the electrode more prone to breakage, and consequently leads to lower battery cycle stability.

[0078] Figure 4 The first-cycle charge-discharge curves of lithium-ion half-cells prepared using silicon-carbon anode plates from Application Example 1 and Comparative Examples 1 and 2 are shown in comparison. Figure 5 This is a comparison of the first-cycle charge-discharge curves of lithium-ion half-cells prepared using the silicon-carbon anode plates of Application Example 2 and Comparative Examples 1 and 2. (Combined with...) Figure 4 , Figure 5 It can be seen that the silicon-carbon anode using the aqueous composite binder of the present invention has a higher specific charge capacity, indicating that the irreversible capacity of the electrode is greatly reduced compared to the comparative example. For example, excessive electrolyte consumption caused by surface defects is greatly reduced, and the overall polarization of the electrode is smaller, which helps the battery to maintain long-term cycle stability.

[0079] Figure 6 , 7 The graph shows a comparison of the cycle performance of lithium-ion half-cells prepared using silicon-carbon anode sheets from different application examples (application examples 2 and 3) and comparative application examples 1 and 2. It can be seen that the silicon-carbon anode using the aqueous composite binder of the present invention has higher specific capacity and cycle stability. The high-performance SEI induced by the binder is beneficial to the long cycle performance of the battery, indicating that the binder has a significant effect on the cycle stability of the battery.

[0080] 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 within the protection scope of the present invention.

Claims

1. An aqueous composite binder for silicon-carbon anodes in lithium-ion batteries, characterized in that: The aqueous composite adhesive comprises a first component, a second component, and a third component; the first component, the second component, and the third component account for 30-60%, 20-40%, and 20-40% of the mass fraction of the aqueous composite adhesive, respectively; the first component is one or more of the guanidine-containing compound shown in Formula 1 or its salt; the second component is one or two glutamic acid chain derivatives; and the third component is sodium poly(4-styrenesulfonate) or sodium polyanilinesulfonate. In Formula 1, R1 is a straight-chain or branched alkyl group with 1 to 10 atoms; R2 is -NH2, -COOH, -SO2-Ph-CH3, ... R3 can be any one of -CH3 and -H; R3 can be any one of -NH2, -COOH and -H.

2. The aqueous composite binder for silicon-carbon anodes of lithium-ion batteries according to claim 1, characterized in that: The guanidine-containing compound is N-p-toluenesulfonyl-L-arginine or Nα-benzoyl-L-arginine.

3. The aqueous composite binder for silicon-carbon anodes of lithium-ion batteries according to claim 1, characterized in that: The glutamate chain derivative is one or two of L-glutamate polymer, N-(4-carbamoyl)-L-glutamate, and L-γ-carboxyglutamate.

4. The aqueous composite binder for silicon-carbon anodes of lithium-ion batteries according to claim 3, characterized in that: The relative molecular weight of the L-glutamic acid polymer is 500,000-700,000, and the average molecular weight of the third component is 100,000-300,000.

5. The method for preparing the aqueous composite binder for silicon-carbon anodes of lithium-ion batteries according to any one of claims 1-4, characterized in that, The steps are as follows: (1) Dissolve the first component, the second component and the third component in deionized water to obtain a mixed solution; (2) Dry the mixed solution to obtain a solid aqueous composite adhesive.

6. The method for preparing the aqueous composite binder for silicon-carbon anodes of lithium-ion batteries according to claim 5, characterized in that: The total mass ratio of the first component, the second component, and the third component to the volume ratio of deionized water is 0.1 g:(1-4) mL; the stirring temperature is 20-30℃; and the stirring time is 1-4 h.

7. A silicon-carbon anode for lithium-ion batteries, characterized in that: The lithium-ion battery silicon-carbon anode comprises the aqueous composite binder, silicon-carbon anode material, and conductive agent as described in any one of claims 1-4.

8. The lithium-ion battery silicon-carbon anode according to claim 7, characterized in that, The mass ratio of the silicon-carbon anode material, conductive agent, and aqueous composite binder is (16-19):(1-2):(1-3); the conductive agent is any one of acetylene black, Ketjen black, carbon nanotubes, Super P, and graphene; the silicon-carbon anode material is a commercially available silicon-carbon material.

9. A lithium-ion battery, characterized in that, The lithium-ion battery includes the silicon-carbon anode of the lithium-ion battery as described in claim 7 or 8.

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