Silicon-based negative electrode slurry, preparation method therefor, and negative electrode piece

Patent metadata

Field	Value
Publication number	US-12431504-B2
Application number	US-202418852680-A
Country	US
Kind code	B2
Filing date	Mar 1, 2024
Priority date	Mar 31, 2023
Publication date	Sep 30, 2025
Grant date	Sep 30, 2025

Abstract

The present application relates to a silicon-based negative electrode slurry, a preparation method therefor and a negative electrode piece. The preparation method comprises: (1) mixing CMC and a solvent to obtain a primary adhesive solution; (2) mixing PAA, a silicon-based negative electrode material, a conductive agent, a solvent, and the obtained adhesive solution, then performing double planetary mixing to obtain a secondary glue solution; (3) mixing a solvent and the obtained secondary adhesive solution to obtain a coarse slurry; and (4) mixing the SBR and the obtained coarse slurry to obtain a silicon-based negative electrode slurry. In the homogenization method of the present application, after the PAA and the SBR are incorporated in separate steps, a three-dimensional cross-linked network can be formed, good tensile behavior is exhibited, a bonding effect is improved, same can adapt well to volumetric expansion of silicon negative electrodes, and the cycling stability of silicon negative electrodes is improved.

First claim

What is claimed is:

1. A preparation method for a silicon-based negative electrode slurry, which comprises:
(1) mixing sodium carboxymethyl cellulose (CMC) and a first solvent to obtain a primary binder liquid;
(2) mixing polyacrylic acid (PAA), a silicon-based negative electrode material, a conductive agent, a second solvent, and the obtained binder liquid, and performing double-planetary stirring to obtain a secondary binder liquid;
(3) mixing a third solvent and the obtained secondary binder liquid to obtain a crude slurry; and
(4) mixing styrene butadiene rubber (SBR) and the obtained crude slurry to obtain the silicon-based negative electrode slurry.

2. The preparation method according to claim 1 , wherein the first solvent, the second solvent, and the third solvent are water;
optionally, a mass of the first solvent in step (1) is 35-40 wt % of the total amount of the solvents in the silicon-based negative electrode slurry;
optionally, a mass of the second solvent in step (2) is 55-65 wt % of the total amount of the solvents in the silicon-based negative electrode slurry;
optionally, a mass of the third solvent in step (3) is 1-3 wt % of the total amount of the solvents in the silicon-based negative electrode slurry.

3. The preparation method according to claim 2 , wherein a mass of the first solvent in step (1) is 35-40 wt % of the total amount of the solvents in the silicon-based negative electrode slurry.

4. The preparation method according to claim 2 , wherein a mass of the second solvent in step (2) is 55-65 wt % of the total amount of the solvents in the silicon-based negative electrode slurry.

5. The preparation method according to claim 2 , wherein a mass of the third solvent in step (3) is 1-3 wt % of the total amount of the solvents in the silicon-based negative electrode slurry.

6. The preparation method according to claim 1 or 2 , wherein a solid content of the primary binder liquid in step (1) is 1-2%;
optionally, a mass of the CMC in step (1) is 0.1-0.5 wt % of the mass of the silicon-based negative electrode slurry;
optionally, a mass of the PAA in step (2) is 1-1.5 wt % of the mass of the silicon-based negative electrode slurry;
optionally, a mass of the silicon-based negative electrode material in step (2) is 96-97 wt % of the mass of the silicon-based negative electrode slurry;
optionally, a mass of the conductive agent in step (2) is 0.5-1.5 wt % of the mass of the silicon-based negative electrode slurry;
optionally, a mass of the SBR in step (4) is 1-2 wt % of the mass of the silicon-based negative electrode slurry.

7. The preparation method according to any one of claims 1-6 , wherein the process of the double-planetary stirring in step (2) comprises low-speed stirring first, followed by medium-speed stirring;
1 optionally, the low-speed stirring is performed at a revolution speed of 20-30 rpm and a rotation speed of 100-300 rpm;
optionally, the low-speed stirring is performed for a period of 10-30 min;
optionally, the medium-speed stirring is performed at a revolution speed of 15-25 rpm and a rotation speed of 1500-2000 rpm;
optionally, the medium-speed stirring is performed for a period of 80-100 min.

8. The preparation method according to claim 7 , wherein the low-speed stirring is performed at a revolution speed of 20-30 rpm and a rotation speed of 100-300 rpm;
optionally, the low-speed stirring is performed for a period of 10-30 min.

9. The preparation method according to claim 7 , wherein the medium-speed stirring is performed at a revolution speed of 15-25 rpm and a rotation speed of 1500-2000 rpm;
optionally, the medium-speed stirring is performed for a period of 80-100 min.

10. The preparation method according to any one of claims 1-7 , wherein stirring is further comprised after the mixing in step (3);
optionally, the stirring is performed at a revolution speed of 20-30 rpm and a rotation speed of 100-300 rpm;
optionally, the stirring is performed for a period of 80-100 min;
optionally, kneading is further comprised after the stirring;
optionally, the crude slurry in step (3) has a solid content of 50-55%;
optionally, the crude slurry in step (3) has a viscosity of 3500-4500 mPa·s.

11. The preparation method according to any one of claims 1-10 , wherein the SBR in step (4) is an SBR dispersing solution;
optionally, the SBR dispersing solution has a mass concentration of 35-45 wt %;
optionally, vacuuming and double-planetary stirring are further comprised after the mixing in step (4);
optionally, the double-planetary stirring is performed for a period of 20-40 min;
optionally, the double-planetary stirring is performed at a revolution speed of 20-30 rpm and a rotation speed of 700-900 rpm;
optionally, the silicon-based negative electrode slurry obtained in step (4) is stored under vacuum.

12. The preparation method according to any one of claims 1-3 , wherein the preparation method comprises:
(1) dividing solvent water which is required for preparing the silicon-based negative electrode slurry into a first solvent, a second solvent, and a third solvent, wherein a mass of the first solvent is 35-40 wt % of the total mass of the solvent water, a mass of the second solvent is 55-65 wt % of the total mass of the solvent water, and a mass of the third solvent is 1-3 wt % of the total mass of the solvent water; mixing CMC and the first solvent to obtain a primary binder liquid with a solid content of 1-2%; a mass of the CMC is 0.1-0.5 wt % of the mass of the silicon-based negative electrode slurry;
2 (2) mixing PAA, a silicon-based negative electrode material, a conductive agent, the second solvent, and the obtained binder liquid according to a formula amount, and performing double-planetary stirring, which comprises first performing low-speed stirring at a revolution speed of 20-30 rpm and a rotation speed of 100-300 rpm for 10-30 min, and then performing medium-speed stirring at a revolution speed of 15-25 rpm and a rotation speed of 1500-2000 rpm for 80-100 min, to obtain a secondary binder liquid; a mass of the PAA is 1-1.5 wt % of the mass of the silicon-based negative electrode slurry; a mass of the silicon-based negative electrode material is 96-97 wt % of the mass of the silicon-based negative electrode slurry; and a mass of the conductive agent is 0.5-1.5 wt % of the mass of the silicon-based negative electrode slurry;
(3) mixing the third solvent and the obtained secondary binder liquid, stirring at a revolution speed of 20-30 rpm and a rotation speed of 100-300 rpm for 80-100 min, and then kneading to obtain a crude slurry with a solid content of 50-55% and a viscosity of 3500-4500 mPa·s; and
(4) mixing an SBR dispersing solution with a mass concentration of 35-45 wt % and the obtained crude slurry, vacuumizing, and performing double-planetary stirring at a revolution speed of 20-30 rpm and a rotation speed of 700-900 rpm for 20-40 min to obtain the silicon-based negative electrode slurry; a mass of the SBR is 1-2 wt % of the mass of the silicon-based negative electrode slurry.

13. A silicon-based negative electrode slurry, which is prepared by the preparation method according to any one of claims 1-12 .

14. The silicon-based negative electrode slurry according to claim 13 , wherein the silicon-based negative electrode slurry has a solid content of 50-55%;
optionally, the silicon-based negative electrode slurry has a viscosity of 2500-4500 cp.

15. A negative electrode sheet, which is prepared from the silicon-based negative electrode slurry according to claim 13 or 14 .

16. The preparation method according to cl

Assignees

• Eve Energy Co Ltd

Inventors

• Xue Yang
• Liu Shengqi
• Song Pengyuan

Classifications

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/04

  Processes of manufacture in general · CPC title

• B01F2215/0495

  Numerical values of viscosity of substances · CPC title

• B01F2215/0481

  Numerical speed values · CPC title

• B01F2215/0477

  Numerical time values · CPC title