A battery negative electrode binder for lithium battery and preparation method thereof, a battery negative electrode sheet and a lithium battery

Abstract

The present invention relates to a battery negative electrode binder for lithium battery and a preparation method thereof, a battery negative electrode plate and a lithium battery. The battery negative electrode binder comprises: 1-3 parts of multi-walled carbon nanotubes, 10-15 parts of lithium alginate, and 480-520 parts of styrene-butadiene rubber emulsion. Lithium alginate can make the multi-walled carbon nanotubes disperse evenly. When preparing the negative electrode plate, the negative electrode binder dissolves the negative electrode active material and the conductive agent to form a negative electrode material. Since the multi-walled carbon nanotubes enhance the mechanical properties and conductivity of the negative electrode plate, lithium alginate can enhance the bonding properties of the negative electrode plate, and can also ensure that the multi-walled carbon nanotubes are stably dispersed in the negative electrode material and the negative electrode binder, so that the performance of the negative electrode plate is highly uniform. And lithium alginate can supplement lithium to the negative electrode plate. The styrene-butadiene rubber emulsion provides bonding properties for the negative electrode plate, and provides mechanical properties, thermal stability and conductivity for the membrane formed by the negative electrode material. The present invention has low energy consumption and is environmentally friendly without affecting the performance.

Description

Technical Field

[0001] The present invention relates to the technical field of battery binders, and in particular to a battery negative electrode binder used in lithium batteries and a preparation method thereof, a battery negative electrode sheet and a lithium battery. Background Art

[0002] Lithium batteries, especially lithium-ion batteries, need to have high thermal stability, mechanical strength and bonding properties in their negative electrode binders. Existing negative electrode binders mainly include composite binders composed of styrene-butadiene rubber and sodium carboxymethyl cellulose, and polyacrylic acid binders, among which polyacrylic acid binders are more commonly used in silicon-based negative electrode materials.

[0003] The Chinese patent application with publication number CN118109140A published on May 31, 2024 discloses a conductive composite binder, a preparation method, an electrode sheet and an application, which relates to the technical field of polymer conductive binders. The conductive composite binder is made of the following components by weight: 100 parts of a mixture of styrene-butadiene rubber and polythiophene; 0.2-0.8 parts of attapulgite; 0.4-1 parts of graphene oxide; wherein, in the mixture of styrene-butadiene rubber and polythiophene, styrene-butadiene rubber accounts for 80%wt-90%wt. This invention application improves the peel strength of the electrode sheet by using styrene-butadiene rubber and polythiophene with conductive properties, combining the toughness of styrene-butadiene rubber with the rigidity of polythiophene; adding attapulgite, whose rod-like structure forms a channel between the mixture of styrene-butadiene rubber and polythiophene, and attapulgite has a wider porous channel, which is convenient for the movement of electrons and lithium ions; adding graphene oxide to be embedded in the porous channel of attapulgite to accelerate the movement of electrons and lithium ions. However, the prior art needs to be processed at a temperature above 100° C., and since no solvent is added, it needs to be mixed with the active substance by extrusion and rolled. Therefore, the prior art has the problems of high energy consumption and poor environmental friendliness. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the first object of the present invention is to provide a battery negative electrode binder for lithium batteries, which has the advantages of low processing temperature, low preparation energy consumption and environmental friendliness.

[0005] In order to solve the problems existing in the above-mentioned prior art, the second object of the present invention is to provide a method for preparing a battery negative electrode binder used in lithium batteries, which has low processing temperature, low preparation energy consumption, and is environmentally friendly.

[0006] In order to solve the problems existing in the above-mentioned prior art, the third object of the present invention is to provide a battery negative electrode plate.

[0007] In order to solve the problems existing in the above-mentioned prior art, the fourth object of the present invention is to provide a lithium battery.

[0008] In order to achieve the first object of the present invention, the following technical scheme is adopted:

[0009] The invention provides a battery negative electrode binder used for lithium batteries, which comprises the following components in parts by weight: 1-3 parts of multi-walled carbon nanotubes, 10-15 parts of lithium alginate, and 480-520 parts of styrene-butadiene rubber emulsion.

[0010] In specific implementation, lithium alginate can have a solubilizing effect on multi-walled carbon nanotubes, so that the multi-walled carbon nanotubes are evenly dispersed in the negative electrode binder. When preparing the negative electrode plate, the negative electrode binder dissolves the negative electrode active material and the conductive agent to form a negative electrode material, and the negative electrode material is applied to the negative electrode plate, dried and rolled. Since the multi-walled carbon nanotubes enhance the mechanical properties and conductivity of the membrane formed by the negative electrode material, lithium alginate can enhance the bonding performance of the negative electrode plate, and can also ensure that the multi-walled carbon nanotubes are stably dispersed in the negative electrode binder and the negative electrode material, so that the performance of the negative electrode plate is highly uniform. And lithium alginate can supplement lithium to the negative electrode membrane. Styrene-butadiene rubber emulsion can provide certain bonding properties for the negative electrode plate, and make the negative electrode membrane tightly bonded to the copper foil and have certain mechanical properties, thermal stability and conductivity. The main solvent of the present invention is water, which has low energy consumption and is environmentally friendly without affecting the performance.

[0011] Preferably, the solid content of the styrene-butadiene rubber emulsion is 40%-60%.

[0012] In a specific implementation, if the solid content of the styrene-butadiene rubber emulsion is too small, its bonding performance will be reduced, and if the solid content is too large, the stability of the negative electrode binder will be affected.

[0013] Preferably, the styrene-butadiene rubber emulsion includes one or more of AL-1002, AL-3001A, and SN-307R.

[0014] During specific implementation, the above-mentioned styrene-butadiene rubber emulsions are all commercially available products.

[0015] Preferably, the purity of the lithium alginate is 99% or above.

[0016] In specific implementation, the lithium alginate is a commercially available product, and its molecular weight is generally above 100,000 and below 1,000,000. In principle, the optimal molecular weight of the lithium alginate is about 200,000, and preferably not more than 1,000,000. A molecular weight that is too high will cause the negative electrode binder to be too viscous, making it difficult to dissolve the conductive agent and the negative electrode active material and form a uniform negative electrode film. If the molecular weight is less than 100,000, it is easy to cause the dispersion ability of the multi-walled carbon nanotubes to decrease, thereby causing the multi-walled carbon nanotubes to agglomerate.

[0017] The present invention also provides a method for preparing a negative electrode binder for lithium batteries as described in any of the above technical solutions, comprising the following steps: dissolving lithium alginate in styrene-butadiene rubber emulsion, heating and stirring until uniform, adding multi-walled carbon nanotubes, continuing to heat and stir and ultrasonicate until uniform to obtain the negative electrode binder.

[0018] In specific implementation, under the premise that the multi-walled carbon nanotubes are not subjected to hydroxylation treatment, lithium alginate can dissolve a certain amount of multi-walled carbon nanotubes through an organic non-covalent effect, provided that the lithium alginate is first uniformly dissolved in a styrene-butadiene rubber emulsion under heating and stirring conditions, and the multi-walled carbon nanotubes are added while heating and stirring, and after the addition is completed, the system is stirred for a period of time, and then the entire system is ultrasonicated. After the ultrasonication is completed, the multi-walled carbon nanotubes and lithium alginate achieve organic non-covalent bonding, the surface of the multi-walled carbon nanotubes is hydrophobic, the hydrophobic end of the lithium alginate surrounds the multi-walled carbon nanotubes, and the hydrophilic groups form hydrogen bonds with water in the emulsion system outward, so that the carbon nanotubes are uniformly dispersed in the emulsion, and the styrene-butadiene rubber is also uniformly dispersed in the emulsion under the action of an emulsifier or CMC-Na. Furthermore, when the three coexist in an emulsion, they are heated, stirred and ultrasonicated until uniform, so that the hydrophilic groups outside the styrene-butadiene rubber and the hydrophilic groups of the lithium alginate make the two miscible and miscible with water, achieving non-covalent bonding, and then the negative electrode material is formed with the negative electrode active material and the conductive agent and dried and rolled on the copper foil to form a membrane.

[0019] Preferably, the multi-walled carbon nanotubes are treated with the following steps and then added to the styrene-butadiene rubber emulsion, hydroxylated multi-walled carbon nanotubes are used or the multi-walled carbon nanotubes are treated with a hydroxylation method, and then the hydroxylated multi-walled carbon nanotubes are added to N parts of E solvent, and methacrylic acid is added dropwise to the mixture of the multi-walled carbon nanotubes and E solvent at A1 mL / min for every MmL of E solvent, and the reaction is carried out at a constant temperature of T1 and a stirring rate of B1 rpm until the reaction is stopped at time t1, and the mixture is filtered and dried.

[0020] In specific implementation, the hydroxylated multi-walled carbon nanotubes are hydroxylated multi-walled carbon nanotubes in the prior art, and those skilled in the art can select hydroxylated multi-walled carbon nanotubes in the prior art according to actual needs. A solvent that can dissolve hydroxylated carbon nanotubes and make the hydroxylated carbon nanotubes evenly distributed in the solvent, specifically, some groups in the solvent can react with hydroxyl groups. Methacrylic acid is reacted with multi-walled carbon nanotubes in an E solvent, so that the -COOH in the methacrylic acid reacts with the -OH and is grafted onto the multi-walled carbon nanotubes, and an alkali catalyst is used during the reaction and the pH is maintained at 9-10.

[0021] Preferably, the E solvent is one or both of acetone or chloroform, N is 20-25, M is 130-310, A1 is 0.2-0.5 mL / min, T1 is 50° C.-55° C., B1 is 800-1000 rpm, and t1 is 2.5-3 hours.

[0022] In a specific implementation, M is the sum of the quotient of the acetone content and the acetone density in N parts of the E solvent and the quotient of the chloroform content and the chloroform density.

[0023] Preferably, after adding the multi-walled carbon nanotubes, in-situ polymerization is carried out at 50° C.-60° C., 450W-500W ultrasonic power, 60KHz-100KHz ultrasonic frequency and 800-1000rpm stirring speed, and the polymerization is stopped after the reaction for 20-25 minutes.

[0024] In a specific implementation, when hydroxylated multi-walled carbon nanotubes are used and modified by methacrylic acid, the hydroxyl active sites react with carboxyl groups, thereby introducing double bonds. The modified multi-walled carbon nanotubes are then dissolved in a mixture of styrene-butadiene rubber latex and lithium alginate to form a negative electrode binder. At this time, the modified multi-walled carbon nanotubes are uniformly distributed in the negative electrode binder under the wrapping of lithium alginate, and the modified multi-walled carbon nanotubes, lithium alginate and styrene-butadiene rubber are also uniformly distributed in the negative electrode binder. When the temperature is 50°C-60°C, the ultrasonic power is 450W-500W, and the ultrasonic frequency is 60KHz-100KHz, the double bonds on the modified multi-walled carbon nanotubes approach and react in situ with the double bonds on the styrene-butadiene rubber, so that the modified multi-walled carbon nanotubes are more uniformly distributed in the styrene-butadiene rubber. At this time, the combination of modified multi-walled carbon nanotubes and styrene butadiene rubber through organic covalent effect can make the conductivity and mechanical properties of carbon nanotubes more uniform, cooperate with styrene butadiene rubber and improve the overall performance of the negative electrode binder, while the modified multi-walled carbon nanotubes can drive the lithium alginate to be evenly distributed, closer to styrene butadiene rubber and centered on styrene butadiene rubber in styrene butadiene rubber emulsion, and its bonding performance can be coordinated with the bonding performance of styrene butadiene rubber. Controlling the reaction to stop polymerization after 20-25 minutes can improve the performance of the negative electrode binder in subsequent use and prevent violent polymerization during the reaction.

[0025] Preferably, the initiator used in the polymerization of the negative electrode binder is 10-15 parts of benzoyl peroxide, and the terminator used is 10-15 parts of hydroquinone.

[0026] Preferably, the stirring temperature of lithium alginate is 45°C-50°C, the stirring rate is 500-1000rpm, and the stirring time is 1-1.5 hours. After adding multi-walled carbon nanotubes, the stirring temperature is 45°C-50°C, the stirring rate is 500-1000rpm, the stirring time is 0.5-1 hour, the ultrasonic power is 100W-150W, the ultrasonic frequency is 20KHz-25KHz, and the ultrasonic time is 15-30min.

[0027] The present invention also provides a battery negative electrode plate, which is prepared using the negative electrode binder applied to lithium batteries.

[0028] The present invention also provides a lithium battery, which is made from the above-mentioned battery positive electrode sheet.

[0029] The present invention discloses a battery negative electrode binder for lithium battery, which has the advantages that lithium alginate can dissolve multi-walled carbon nanotubes, so that the multi-walled carbon nanotubes are uniformly dispersed in the negative electrode binder. When preparing the negative electrode plate, the negative electrode binder dissolves the negative electrode active material and the conductive agent to form a negative electrode material, and the negative electrode material is applied to the negative electrode plate, dried and rolled. Since the multi-walled carbon nanotubes enhance the mechanical properties and conductivity of the negative electrode plate, lithium alginate can enhance the bonding performance of the negative electrode plate, and can also ensure that the multi-walled carbon nanotubes are stably dispersed in the negative electrode material and the negative electrode binder, so that the performance of the negative electrode plate is highly uniform. And lithium alginate can supplement lithium to the negative electrode plate. Styrene-butadiene rubber emulsion can provide certain bonding properties for the negative electrode plate, and make the membrane formed by the negative electrode material tightly bonded to the copper foil and have certain mechanical properties, thermal stability and conductivity. The main solvent of the present invention is water, which has low energy consumption and is environmentally friendly without affecting the performance. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the embodiments.

[0031] In the following examples, comparative examples, application examples and method examples of the present invention, the main components involved, unless otherwise specified, are purchased from commercially available products.

[0032] Multi-walled carbon nanotubes were purchased from Jiangsu Xianfeng Nanomaterials Co., Ltd. with a purity of 95%, a length of 10-30 μm, and a diameter of 10-20 nm.

[0033] The hydroxylation method of the multi-walled carbon nanotubes is to first oxidize with mixed acid and then reduce with hydrazine hydrate, and then wash and dry to obtain the hydroxylated multi-walled carbon nanotubes.

[0034] Lithium alginate, purity 99%, was purchased from Guangdong Fangxin Biotechnology Co., Ltd.

[0035] Styrene-butadiene rubber latex, brand SN-307R, Japan Aiyulong brand, purchased from Shanghai Waidian International Trade Co., Ltd. Example

[0036] A method for preparing a negative electrode binder for lithium batteries comprises dissolving 10 parts of lithium alginate in 520 parts of styrene-butadiene rubber emulsion, heating and stirring until uniform, adding 3 parts of multi-walled carbon nanotubes, continuing heating and stirring and ultrasonicating until uniform to obtain the negative electrode binder.

[0037] The stirring temperature of lithium alginate was 45°C, the stirring rate was 500 rpm, and the stirring time was 1 hour. After adding multi-walled carbon nanotubes, the stirring temperature was 45°C, the stirring rate was 500 rpm, and the stirring time was 0.5 hour. The ultrasonic power was 100 W, the ultrasonic frequency was 20 KHz, and the ultrasonic time was 15 min. Example

[0038] A method for preparing a negative electrode binder for lithium batteries comprises dissolving 15 parts of lithium alginate in 480 parts of styrene-butadiene rubber emulsion, heating and stirring until uniform, adding 1 part of multi-walled carbon nanotubes, continuing heating and stirring and ultrasonicating until uniform to obtain the negative electrode binder.

[0039] The stirring temperature of lithium alginate was 50°C, the stirring rate was 1000 rpm, and the stirring time was 1.5 hours. After adding multi-walled carbon nanotubes, the stirring temperature was 50°C, the stirring rate was 1000 rpm, and the stirring time was 1 hour. The ultrasonic power was 150 W, the ultrasonic frequency was 25 KHz, and the ultrasonic time was 30 min. Example

[0040] A method for preparing a negative electrode binder for lithium batteries comprises dissolving 7 parts of lithium alginate in 500 parts of styrene-butadiene rubber emulsion, heating and stirring until uniform, adding 6 parts of multi-walled carbon nanotubes, continuing heating and stirring and ultrasonicating until uniform to obtain the negative electrode binder.

[0041] The stirring temperature of lithium alginate was 48°C, the stirring rate was 700 rpm, and the stirring time was 1.3 hours. After adding multi-walled carbon nanotubes, the stirring temperature was 48°C, the stirring rate was 700 rpm, and the stirring time was 0.7 hours. The ultrasonic power was 120 W, the ultrasonic frequency was 23 KHz, and the ultrasonic time was 20 min. Example

[0042] A method for preparing a negative electrode binder for a lithium battery comprises: before adding multi-walled carbon nanotubes to styrene-butadiene rubber emulsion, hydroxylating the multi-walled carbon nanotubes, and then treating the hydroxylated multi-walled carbon nanotubes in the following manner:

[0043] The hydroxylated multi-walled carbon nanotubes were added to 20 parts of acetone solvent. For every 250 mL of acetone solvent, methacrylic acid was added dropwise to the mixture of multi-walled carbon nanotubes and acetone solvent at a rate of 0.2 mL / min. The mixture was reacted at a constant temperature of 50° C. and a stirring rate of 800 rpm until the reaction was stopped after 2.5 hours. The mixture was filtered and dried.

[0044] 10 parts of lithium alginate are dissolved in 520 parts of styrene-butadiene rubber latex, and 3 parts of treated multi-walled carbon nanotubes are added after heating and stirring. The heating and stirring are continued and ultrasonicated until uniform. In-situ polymerization is carried out at 50° C., 450 W ultrasonic power, 60 KHz ultrasonic frequency, and 800 rpm stirring speed. The polymerization is stopped after the reaction for 20 minutes. At the beginning of the reaction, 10 parts of initiator benzoyl peroxide are added. 3 minutes before the end of the reaction, 10 parts of terminator hydroquinone are added to obtain the negative electrode binder. Example

[0045] A method for preparing a negative electrode binder for a lithium battery, the difference between this embodiment and embodiment 1 is:

[0046] Before adding the multi-walled carbon nanotubes into the styrene-butadiene rubber latex, the multi-walled carbon nanotubes are hydroxylated, and the hydroxylated multi-walled carbon nanotubes are treated as follows:

[0047] The hydroxylated multi-walled carbon nanotubes were added to 20 parts of chloroform solvent. For every 130 mL of chloroform solvent, methacrylic acid was added dropwise to the mixture of multi-walled carbon nanotubes and chloroform solvent at a rate of 0.5 mL / min. The mixture was reacted at a constant temperature of 55° C. and a stirring rate of 1000 rpm until the reaction was stopped after 3 hours, and the mixture was filtered and dried.

[0048] 10 parts of lithium alginate are dissolved in 520 parts of styrene-butadiene rubber latex, and 3 parts of treated multi-walled carbon nanotubes are added after heating and stirring. The mixture is heated, stirred and ultrasonicated until uniform. In-situ polymerization is carried out at 60° C., 500 W ultrasonic power, 100 KHz ultrasonic frequency and 1000 rpm stirring speed. The polymerization is stopped after 25 minutes of reaction. At the beginning of the reaction, 15 parts of initiator benzoyl peroxide are added. 3 minutes before the end of the reaction, 15 parts of terminator hydroquinone are added to obtain the negative electrode binder. Example

[0049] A method for preparing a negative electrode binder for a lithium battery, the difference between this embodiment and embodiment 5 is that no initiator and terminator are added. The remaining components and preparation method are the same as those in embodiment 5.

[0050] Comparative Example 1

[0051] A method for preparing a negative electrode binder for a battery, the difference between this comparative example and Example 1 is that lithium alginate is not added. The remaining components and preparation method are the same as those in Example 1.

[0052] Comparative Example 2

[0053] A method for preparing a negative electrode binder for a battery, the difference between this comparative example and Example 1 is that there are no multi-walled carbon nanotubes. The remaining components and preparation method are the same as those in Example 1.

[0054] Comparative Example 3

[0055] A method for preparing a negative electrode binder for a battery, the difference between this comparative example and Example 1 is that there is no styrene-butadiene rubber. The remaining components and preparation method are the same as those in Example 1.

[0056] Method example

[0057] The negative electrode binders of Examples 1-5 and Comparative Examples 1-3 were used to prepare negative electrode sheets. The specific preparation method is as follows:

[0058] While stirring, add 2 parts of conductive carbon black Super-P and 54 parts of graphite to the negative electrode binder in sequence and mix well to obtain a slurry. Filter out the solid matter in the slurry and coat the solid matter on a copper foil with a thickness of 100 μm. Completely dry it in an oven at 75°C and roll it to obtain a negative electrode sheet.

[0059] Application Examples 1 to 5 use the negative electrode binders and the methods in Examples 1 to 5 to prepare negative electrode sheets, and Application Examples 7 to 9 use the negative electrode binders and the methods in Comparative Examples 1 to 3 to prepare negative electrode sheets.

[0060] Application Example 6 uses any negative electrode sheet of Application Example 1 to Application Example 5 to prepare a lithium battery.

[0061] The test standards and methods adopted include GB / T 2792-2014, four-probe method and substrate stretching method.

[0062] The four-probe method adopts the four-probe method in the prior art, and the substrate stretching method is as follows:

[0063] The negative electrode binder in the above-mentioned embodiment and comparative example was evenly applied to the surface of the first copper sheet, 1cm×2cm, and the coating thickness was controlled to be 1mm. The second copper sheet, 1cm×2cm, was covered on the surface of the binder. The first copper sheet and the second copper sheet were stretched along 180° to test their tensile force. The test was repeated 5 times in parallel and the average value was taken.

[0064] The specific results are shown in Table 1.

[0065] Table 1 Test results of embodiments, comparative examples and application examples

[0066]

[0067] According to the results of the above-mentioned embodiments, application examples and comparative examples, it can be seen that the technical effect of the embodiments is much higher than that of the comparative examples, and the technical effect of the application examples of the embodiments is much higher than that of the application examples of the comparative examples. Compared with Example 1 and Comparative Example 1, since Comparative Example 1 does not have lithium alginate, multi-walled carbon nanotubes cannot be evenly distributed in the negative electrode binder, resulting in the performance of Comparative Example 1 and its application examples being far inferior to that of Example 1 and its application examples. Compared with Example 2 and Comparative Example 2, since Comparative Example 2 does not have multi-walled carbon nanotubes, the mechanical properties and conductivity of the negative electrode binder decrease, resulting in the performance of Comparative Example 2 and its application examples being far inferior to that of Example 2 and its application examples. Compared with Example 3 and Comparative Example 3, since Comparative Example 3 does not have styrene-butadiene rubber, the other ingredients cannot cooperate with styrene-butadiene rubber to play a bonding role, resulting in the occurrence of powder loss, resulting in the performance of Comparative Example 3 and its application examples being far inferior to that of Example 3 and its application examples. Compared with Example 1, Example 4 and Example 5, since Example 4 and Example 5 adopt modification means for multi-walled carbon nanotubes, double bonds on the surface of multi-walled carbon nanotubes are introduced to connect styrene-butadiene rubber, and lithium alginate is connected by means of organic non-covalent effect, so that the connection between styrene-butadiene rubber, multi-walled carbon nanotubes and lithium alginate is more firm and the distribution is more uniform, and the corresponding performance is further improved, the performance of Example 1 and its application examples is not as good as that of Example 4 and its application examples and Example 5 and its application examples. Compared with Comparative Example 2, Example 5 has a decreased performance due to the lack of double bonds on the surface of multi-walled carbon nanotubes to connect styrene-butadiene rubber.

[0068] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, horizontal" and "top, bottom" are usually for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0069] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A negative electrode binder for lithium batteries, characterized in that: The invention comprises the following components by weight: 1-3 parts of multi-walled carbon nanotubes, 10-15 parts of lithium alginate, and 480-520 parts of styrene-butadiene rubber latex; The solid content of the styrene-butadiene rubber emulsion is 40%-60%; The styrene-butadiene rubber emulsion comprises at least one of AL-1002, AL-3001A, and SN-307R; and / or The purity of the lithium alginate is above 99%; The negative electrode binder is prepared by the following steps: Dissolving a formulated amount of lithium alginate in styrene-butadiene rubber latex, heating and stirring the mixture, adding multi-walled carbon nanotubes, continuing heating and stirring and ultrasonic treatment to perform in-situ polymerization reaction, thereby obtaining the negative electrode binder for lithium batteries; The multi-walled carbon nanotubes are added to the styrene-butadiene rubber latex after the following processing steps: Hydroxylated multi-walled carbon nanotubes are used or multi-walled carbon nanotubes are treated by a hydroxylation method, and the hydroxylated multi-walled carbon nanotubes are added to N parts of E solvent. For each MmL of E solvent, methacrylic acid is added dropwise to the mixture of multi-walled carbon nanotubes and E solvent at a rate of A1 mL / min, and the mixture is reacted at a constant temperature of T1 and a stirring rate of B1 rpm until the reaction is stopped at time t1, and the mixture is filtered and dried; The E solvent is at least one of acetone or chloroform, N is 20-25, M is 130-310, A1 is 0.2-0.5 mL / min, T1 is 50° C.-55° C., B1 is 800-1000 rpm, and t1 is 2.5-3 hours.

2. The negative electrode binder for lithium battery according to claim 1, characterized in that: After adding the multi-walled carbon nanotubes, in-situ polymerization is carried out at 50° C.-60° C., 450W-500W ultrasonic power, 60KHz-100KHz ultrasonic frequency and 800-1000rpm stirring speed, and the polymerization is stopped after the reaction for 20-25 minutes.

3. The negative electrode binder for lithium battery according to claim 2, characterized in that: The in-situ polymerization reaction further includes adding 10 to 15 parts of benzoyl peroxide as an initiator and 10 to 15 parts of hydroquinone as a terminator.

4. The negative electrode binder for lithium battery according to claim 1, characterized in that: The heating and stirring temperature for dissolving lithium alginate in styrene-butadiene rubber emulsion is 45°C-50°C, the stirring rate is 500-1000rpm, and the stirring time is 1-1.5 hours. The heating and stirring temperature after adding multi-walled carbon nanotubes is 45°C-50°C, the stirring rate is 500-1000rpm, the stirring time is 0.5-1 hour, the ultrasonic power is 100W-150W, the ultrasonic frequency is 20KHz-25KHz, and the ultrasonic time is 15-30min.

5. A battery negative electrode plate, characterized in that: The invention is prepared by using the negative electrode binder for lithium battery according to any one of claims 1 to 4.

6. A lithium battery, characterized in that: It is made from the battery negative electrode sheet described in claim 5.

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