Battery negative electrode slurry and preparation method thereof

Abstract

The invention provides battery negative electrode slurry and a preparation method thereof. The battery negative electrode slurry comprises the following components in parts by mass: 18-40 parts of silicon carbon; 56 to 78 parts of graphite; 0.2 to 0.83 part of conductive carbon black; 0.1 to 0.35 part of a water system single-walled carbon nanotube; 2.5 to 4 parts of a polyacrylic acid binder; 0.25 to 0.83 part of sodium carboxymethyl cellulose; 0-0.5 part of styrene butadiene rubber; 50 to 140 parts of deionized water; 4-12 parts of a water-based dispersant; 4-12 parts of an auxiliary agent; according to the invention, the proportion of the polyacrylic acid binder, the sodium carboxymethyl cellulose and the carbon nanotube conductive slurry in the formula of the silicon-carbon negative electrode is optimized, then the stirring speed, the stirring mode, the stirring temperature and the charging sequence are accurately adjusted, and the alcohol additive is added at the final stage of stirring, so that the problems of bubbles and agglomeration of the silicon-carbon slurry are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion batteries, and in particular to a battery negative electrode slurry and a preparation method thereof. Background Art

[0002] Among numerous energy storage technologies, lithium-ion batteries, with their high energy density, high conversion efficiency, and fast response speed, have become the mainstream energy storage device. They are the preferred power source for portable electronic devices, electric vehicles, and large-scale energy storage systems. However, with the in-depth development and application of lithium batteries, the most commercially mature graphite anode has gradually reached its theoretical capacity limit, making it difficult to meet the growing demand for high energy. The development of new high-energy-density anode materials is urgent.

[0003] The theoretical specific capacity of silicon-based anode (4200 mAh / g) is much higher than that of traditional graphite anode (372 mAh / g), and its lithium insertion potential is moderate (0.4V vs. Li + / Li), has a lower risk of lithium plating than graphite, and is therefore safer. In addition, silicon is abundant in reserves, low in cost and environmentally friendly. Based on these advantages, silicon-based anode materials are regarded as ideal candidates for the next generation of high-energy-density lithium-ion battery anode materials. However, silicon has low intrinsic conductivity, and the lithium insertion / delithiation process is accompanied by a dramatic volume change (about 300%), which causes the active material to fall off the current collector during charge and discharge, seriously affecting the rate performance and cycle life. In addition, silicon has a high specific surface energy. The surface of currently mass-produced CVD silicon-carbon materials generally contains a graphite coating. The coating is easily broken under high-speed stirring, resulting in a large number of bubbles and agglomeration during slurry preparation, and pits, pinholes and scratches are prone to occur during the subsequent coating process. Therefore, the ratio of lithium-containing binder and conductive agent and the slurry preparation process will be very important for improving the electrochemical performance of silicon-carbon materials. It is urgent to develop a silicon-carbon anode slurry and a method for preparing silicon-carbon anode slurry to obtain a product with both high specific capacity and cycle stability.

[0004] To this end, we propose a battery negative electrode slurry and its preparation method to solve the problems of bubbles and agglomeration during silicon-carbon negative electrode slurry preparation and the problems of pits, pinholes and scratches during coating, thereby improving the cycle stability of high-energy-density silicon-based lithium batteries. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art. In order to achieve the above purpose, the present invention adopts the following technical solutions: A battery negative electrode slurry comprises the following components in parts by weight: 18-40 parts of silicon carbon; 56-78 parts of graphite; 0.2-0.83 parts of conductive carbon black; 0.1-0.35 parts of aqueous single-walled carbon nanotubes; 2.5-4 parts of polyacrylic acid binder; 0.25-0.83 parts of sodium carboxymethyl cellulose; 0-0.5 parts of styrene-butadiene rubber; 50-140 parts of deionized water; 4-12 parts of aqueous dispersant; and 4-12 parts of additives.

[0006] More preferably, the aqueous dispersant is butanediol.

[0007] More preferably, the auxiliary agent comprises one or both of anhydrous ethanol and isopropyl alcohol.

[0008] The present invention increases the ratio of binder and single-walled carbon nanotubes compared to traditional negative electrode slurries, has a stronger binding force on silicon-carbon materials, and can reduce the risk of the dressing falling off the current collector after expansion.

[0009] A method for preparing a battery negative electrode slurry comprises the following steps: Step 1: Add sodium carboxymethyl cellulose and deionized water into a planetary mixer and stir for 60-120 minutes to prepare a sodium carboxymethyl cellulose glue solution with a solid content of 1-2%. Set the revolution speed to 20-35 rpm, the rotation speed to 500-800 rpm, and the stirring temperature to 10-45°C. Step 2: Add the sodium carboxymethyl cellulose glue obtained in step 1 and half of the graphite into a planetary mixer and dry mix for 10-30 minutes. Set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C. Step 3: Add the remaining graphite and part of the deionized water to the slurry obtained in step 2, stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 300-800 rpm, and the stirring temperature to 10-45°C; Step 4: Add conductive carbon black to the slurry obtained in step 3 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 5: Add the aqueous carbon nanotube conductive slurry to the slurry obtained in step 4 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 6: After adding silicon carbon to the slurry obtained in step 5, pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 7: Add the polyacrylic acid binder and the remaining deionized water to the slurry obtained in step 6 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 700-900 rpm, and the stirring temperature to 10-45°C; then turn off the circulating water, open the vacuum condition and stir at full speed for 100-180 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 1900-2400 rpm, the stirring temperature to 25-45°C, and the vacuum degree ≤-60 kPa; Step 8: Add butanediol, additives and styrene-butadiene rubber to the slurry obtained in step 7 in sequence, stir under vacuum conditions for 20-45 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 900-1200 rpm, the stirring temperature to 25-45°C, and the vacuum degree to ≤-60 kPa; Step 9: The slurry obtained in step 8 is rotated forward for 20-45 minutes, reversed for 20-45 minutes, and then forward for 20-45 minutes under vacuum conditions. The revolution speed is set to 10-15 rpm, the rotation speed is set to 80-120 rpm, the stirring temperature is set to 25-45°C, and the vacuum degree is set to ≤-60 kPa; Step 10: Finally, filter with a sieve to obtain a high energy density battery silicon-carbon negative electrode slurry.

[0010] Further preferably, in step 3, the solid content of the slurry is controlled at 64-70%.

[0011] Further preferably, in step 7, the slurry viscosity is controlled at 3500-4500 mPa.s.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention optimizes the ratio of polyacrylic acid binder, sodium carboxymethyl cellulose and carbon nanotube conductive slurry in the silicon-carbon negative electrode formula, and then significantly improves the bubble and agglomeration problems of the silicon-carbon slurry by precisely adjusting the stirring speed, stirring method, stirring temperature and addition sequence, and adding an alcohol additive at the end of stirring. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A comparison diagram of the silicon-carbon negative electrode slurry states of the embodiment and the comparative example; Figure 2 1 is a comparison diagram of the coating state of the silicon-carbon negative electrode of the embodiment and the comparative example; Figure 3 The figure is a cycle performance curve of a soft-pack battery prepared with the negative electrode slurry of the embodiment. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0015] Reference Figure 1-Figure 3 , a battery negative electrode slurry, comprising the following components in parts by mass: 18-40 parts of silicon carbon; 56-78 parts of graphite; 0.2-0.83 parts of conductive carbon black; 0.1-0.35 parts of aqueous single-walled carbon nanotubes; 2.5-4 parts of polyacrylic acid binder; 0.25-0.83 parts of sodium carboxymethyl cellulose; 0-0.5 parts of styrene-butadiene rubber; 50-140 parts of deionized water; 4-12 parts of aqueous dispersant; and 4-12 parts of additives.

[0016] The aqueous dispersant is butanediol; the auxiliary agent comprises one or both of anhydrous ethanol and isopropyl alcohol.

[0017] A method for preparing a battery negative electrode slurry comprises the following steps: Step 1: Add sodium carboxymethyl cellulose and deionized water into a planetary mixer and stir for 60-120 minutes to prepare a sodium carboxymethyl cellulose glue solution with a solid content of 1-2%. Set the revolution speed to 20-35 rpm, the rotation speed to 500-800 rpm, and the stirring temperature to 10-45°C. Step 2: Add the sodium carboxymethyl cellulose glue obtained in step 1 and half of the graphite into a planetary mixer and dry mix for 10-30 minutes. Set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C. Step 3: Add the remaining graphite and part of the deionized water to the slurry obtained in step 2, stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 300-800 rpm, and the stirring temperature to 10-45°C; In step 3, the solid content of the slurry is controlled at 64-70%.

[0018] Step 4: Add conductive carbon black to the slurry obtained in step 3 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 5: Add the aqueous carbon nanotube conductive slurry to the slurry obtained in step 4 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 6: After adding silicon carbon to the slurry obtained in step 5, pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 7: Add the polyacrylic acid binder and the remaining deionized water to the slurry obtained in step 6 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 700-900 rpm, and the stirring temperature to 10-45°C; then turn off the circulating water, open the vacuum condition and stir at full speed for 100-180 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 1900-2400 rpm, the stirring temperature to 25-45°C, and the vacuum degree ≤-60 kPa; In step 7, the slurry viscosity is controlled at 3500-4500 mPa.s.

[0019] Step 8: Add butanediol, additives and styrene-butadiene rubber to the slurry obtained in step 7 in sequence, stir under vacuum conditions for 20-45 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 900-1200 rpm, the stirring temperature to 25-45°C, and the vacuum degree to ≤-60 kPa; Step 9: The slurry obtained in step 8 is rotated forward for 20-45 minutes, reversed for 20-45 minutes, and then forward for 20-45 minutes under vacuum conditions. The revolution speed is set to 10-15 rpm, the rotation speed is set to 80-120 rpm, the stirring temperature is set to 25-45°C, and the vacuum degree is set to ≤-60 kPa; Step 10: Finally, filter with a sieve to obtain a high energy density battery silicon-carbon negative electrode slurry. Example

[0020] The raw materials of the battery negative electrode slurry are composed by weight of: 38 parts of silicon carbon, 56 parts of graphite, 0.83 parts of conductive carbon black, 0.35 parts of single-walled carbon nanotubes, 0.82 parts of sodium carboxymethyl cellulose, 4 parts of polyacrylic acid binder, 136 parts of deionized water, 8 parts of butanediol and 8 parts of anhydrous ethanol.

[0021] The method for preparing a negative electrode slurry for a battery comprises the following steps: Step 1: Sodium carboxymethyl cellulose and deionized water were added to a planetary mixer and stirred for 60 minutes to prepare a sodium carboxymethyl cellulose glue solution with a solid content of 2% at an orbital speed of 25 rpm, a rotation speed of 500 rpm, and a stirring temperature of 10-45°C; Step 2: Add the sodium carboxymethyl cellulose glue obtained in step 1 and half of the graphite into a planetary mixer and dry mix for 15 minutes at an orbital speed of 25 rpm, a rotation speed of 300 rpm, and a stirring temperature of 10-45°C; Step 3: Add the remaining graphite and part of the deionized water to the slurry obtained in step 2, and stir for 55 minutes at an orbital speed of 25 rpm, a rotation speed of 300-800 rpm, and a stirring temperature of 10-45°C; Step 4: Add conductive carbon black to the slurry obtained in step 3 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then stir at an increased speed for 45 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 5: Add the aqueous carbon nanotube conductive slurry to the slurry obtained in step 4 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then stir at an increased speed for 60 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 6: Add silicon carbon to the slurry obtained in step 5 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then stir at an increased speed for 60 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 7: Add the polyacrylic acid binder and the remaining deionized water to the slurry obtained in step 6 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 800 rpm, and a stirring temperature of 10-45°C; then turn off the circulating water, open the vacuum condition and stir at full speed for 120 minutes at an orbital speed of 28 rpm, an autorotation speed of 2100 rpm, a stirring temperature of 25-45°C, and a vacuum degree of ≤-60 kPa; Step 8: Butanediol and anhydrous ethanol were added to the slurry obtained in step 7 in sequence, and stirred for 30 minutes under vacuum conditions, with an orbital speed of 28 rpm, a rotation speed of 1000 rpm, a stirring temperature of 25-45°C, and a vacuum degree of ≤-60 kPa; Step 9: The slurry obtained in step 8 is rotated forward for 30 minutes, reversed for 30 minutes, and then forward for 30 minutes under vacuum conditions, with an orbital speed of 10 rpm, a rotation speed of 90 rpm, a stirring temperature of 25-45°C, and a vacuum degree of ≤-60 kPa; then filtered with a 120-mesh sieve to obtain a high-energy-density battery silicon-carbon negative electrode slurry.

[0022] The stirring state of the slurry described in Example 1 is shown in FIG. Figure 1 (b), coating status see Figure 2 (a). Example

[0023] The raw materials of the high energy density silicon-carbon negative electrode slurry are composed by weight of: 19 parts of silicon carbon, 77 parts of graphite, 0.3 parts of conductive carbon black, 0.15 parts of single-walled carbon nanotubes, 0.4 parts of sodium carboxymethyl cellulose, 2.5 parts of polyacrylic acid binder, 0.5 parts of styrene-butadiene rubber, 78 parts of deionized water, 5 parts of butanediol and 10 parts of anhydrous ethanol.

[0024] In Example 2, the proportions of the slurry components are modified compared with Example 1, with 0.5 parts of styrene-butadiene rubber added. Therefore, in step 8, butanediol, anhydrous ethanol and styrene-butadiene rubber need to be added in sequence. The remaining steps are exactly the same as in Example 1.

[0025] Comparative Example: The raw materials of the battery negative electrode slurry are composed by mass of: 38 parts of silicon carbon, 57 parts of graphite, 0.5 parts of conductive carbon black, 0.35 parts of single-walled carbon nanotubes, 0.775 parts of sodium carboxymethyl cellulose, 4.5 parts of polyacrylic acid binder, 92 parts of deionized water and 7 parts of butanediol.

[0026] The method for preparing the silicon-carbon negative electrode slurry comprises the following steps: Step 1: Sodium carboxymethyl cellulose and deionized water were added to a planetary mixer and stirred for 120 minutes to prepare a sodium carboxymethyl cellulose glue solution with a solid content of 2% at an orbital speed of 25 rpm, a rotation speed of 500 rpm, and a stirring temperature of 10-45°C; Step 2: Add the sodium carboxymethyl cellulose glue obtained in step 1 and half of the graphite into a planetary mixer and dry mix for 15 minutes at an orbital speed of 25 rpm, a rotation speed of 300 rpm, and a stirring temperature of 10-45°C; Step 3: Add the remaining graphite and deionized water to the slurry obtained in step 2, and stir for 60 minutes at an orbital speed of 25 rpm, a rotation speed of 500 rpm, and a stirring temperature of 10-45°C; Step 4: Add conductive carbon black to the slurry obtained in step 3 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then increase the speed and stir for 45 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 5: Add the aqueous carbon nanotube conductive slurry to the slurry obtained in step 4 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then stir at an accelerated speed for 60 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 6: Add silicon carbon to the slurry obtained in step 5 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 300 rpm, and a stirring temperature of 10-45°C; then stir at an increased speed for 60 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, and a stirring temperature of 10-45°C; Step 7: Add the aqueous polyacrylic acid binder and the remaining deionized water to the slurry obtained in step 6 and pre-stir for 10 minutes at an orbital speed of 25 rpm, an autorotation speed of 800 rpm, and a stirring temperature of 10-45°C; then, turn on the vacuum condition and stir at full speed for 120 minutes at an orbital speed of 25 rpm, an autorotation speed of 2100 rpm, a stirring temperature of 10-45°C, and a vacuum degree of ≤-60 kPa; Step 8: Add butanediol to the slurry obtained in step 7, and stir under vacuum conditions for 30 minutes at an orbital speed of 25 rpm, a rotation speed of 2100 rpm, a stirring temperature of 10-45°C, and a vacuum degree of ≤-60 kPa; Step 9: Stir the slurry obtained in step 8 for 90 minutes under vacuum conditions, with an orbital speed of 10 rpm, a rotation speed of 90 rpm, a stirring temperature of 10-45°C, and a vacuum degree of ≤-60 KPa; then filter with a 120-mesh sieve to obtain a silicon-carbon negative electrode slurry.

[0027] Compared with the examples, the temperature control, stirring speed and stirring mode in the later stage of pulping are different; the stirring state of the pulp in the comparative example is shown in FIG. Figure 1 (a), coating status see Figure 2 (bc).

[0028] The slurries of the examples and comparative examples were made into negative electrode sheets, and were matched with 9 series high nickel NCM positive electrodes to assemble into soft-pack full batteries. The slurry viscosity, peeling force, membrane resistivity, first efficiency and actual gram capacity are shown in Table 1; the cycle performance of the examples is shown in Figure 3 .

[0029] Table 1

[0030] As can be seen from Table 1, the resistivity of the membrane of the embodiment of the present invention is low, and the initial efficiency is improved by more than 10% compared with the comparative example. A high specific capacity is a prerequisite for preparing a high energy density battery. The reason for the low peeling force of Example 2 is that the silicon content in Example 2 is lower, so the amount of binder in the formulation is reduced; Figure 1 and Figure 2 The silicon-carbon slurry preparation method of the present invention can effectively improve the problems in silicon-carbon negative electrode slurry mixing and coating, which is beneficial to subsequent film production. High-quality electrode sheets are the key to achieving battery cell cycle stability. Figure 3 This is a cycle curve diagram of an embodiment of the present invention, which further illustrates that the silicon-carbon battery with both high specific energy and cycle stability can be obtained by using the silicon-carbon slurry preparation method of the present invention.

[0031] The present invention optimizes the ratio of polyacrylic acid binder, sodium carboxymethyl cellulose and carbon nanotube conductive slurry in the silicon-carbon negative electrode formula, and then significantly improves the bubble and agglomeration problems of the silicon-carbon slurry by precisely adjusting the stirring speed, stirring method, stirring temperature and addition sequence, and adding an alcohol additive at the end of stirring.

[0032] The present invention increases the ratio of binder and single-walled carbon nanotubes compared to traditional negative electrode slurries, has a stronger binding force on silicon-carbon materials, and can reduce the risk of the dressing falling off the current collector after expansion.

Claims

1. A battery negative electrode slurry, characterized in that: The composition includes the following parts by mass: 18-40 parts of silicon carbon; 56-78 parts of graphite; 0.2-0.83 parts of conductive carbon black; 0.1-0.35 parts of aqueous single-walled carbon nanotubes; 2.5-4 parts of polyacrylic acid binder; 0.25-0.83 parts of sodium carboxymethyl cellulose; 0-0.5 parts of styrene-butadiene rubber; 50-140 parts of deionized water; 4-12 parts of aqueous dispersant; and 4-12 parts of additives.

2. The battery negative electrode slurry according to claim 1, characterized in that: The aqueous dispersant is butanediol.

3. The battery negative electrode slurry according to claim 1, characterized in that: The auxiliary agent comprises one or both of anhydrous ethanol and isopropyl alcohol.

4. A method for preparing a battery negative electrode slurry, characterized in that: The following steps are involved: Step 1: Add sodium carboxymethyl cellulose and deionized water into a planetary mixer and stir for 60-120 minutes to prepare a sodium carboxymethyl cellulose glue solution with a solid content of 1-2%. Set the revolution speed to 20-35 rpm, the rotation speed to 500-800 rpm, and the stirring temperature to 10-45°C. Step 2: Add the sodium carboxymethyl cellulose glue obtained in step 1 and half of the graphite into a planetary mixer and dry mix for 10-30 minutes. Set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C. Step 3: Add the remaining graphite and part of the deionized water to the slurry obtained in step 2, stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 300-800 rpm, and the stirring temperature to 10-45°C; Step 4: Add conductive carbon black to the slurry obtained in step 3 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 40-80 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 5: Add the aqueous carbon nanotube conductive slurry to the slurry obtained in step 4 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 6: After adding silicon carbon to the slurry obtained in step 5, pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 200-500 rpm, and the stirring temperature to 10-45°C; then increase the speed and stir for 50-90 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 1900-2400 rpm, and the stirring temperature to 10-45°C; Step 7: Add the polyacrylic acid binder and the remaining deionized water to the slurry obtained in step 6 and pre-stir for 10-30 minutes, set the revolution speed to 20-35 rpm, the rotation speed to 700-900 rpm, and the stirring temperature to 10-45°C; then turn off the circulating water, open the vacuum condition and stir at full speed for 100-180 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 1900-2400 rpm, the stirring temperature to 25-45°C, and the vacuum degree ≤-60 kPa; Step 8: Add butanediol, additives and styrene-butadiene rubber to the slurry obtained in step 7 in sequence, stir under vacuum conditions for 20-45 minutes, set the revolution speed to 25-40 rpm, the rotation speed to 900-1200 rpm, the stirring temperature to 25-45°C, and the vacuum degree to ≤-60 kPa; Step 9: The slurry obtained in step 8 is rotated forward for 20-45 minutes, reversed for 20-45 minutes, and then forward for 20-45 minutes under vacuum conditions. The revolution speed is set to 10-15 rpm, the rotation speed is set to 80-120 rpm, the stirring temperature is set to 25-45°C, and the vacuum degree is set to ≤-60 kPa; Step 10: Finally, filter with a sieve to obtain a high energy density battery silicon-carbon negative electrode slurry.

5. The method for preparing a negative electrode slurry for a battery according to claim 4, characterized in that: In step 3, the solid content of the slurry is controlled at 64-70%.

6. The method for preparing a negative electrode slurry for a battery according to claim 4, characterized in that: In step 7, the slurry viscosity is controlled at 3500-4500 mPa.s.

Images