CN-122025561-A - Silicon-based lithium ion battery negative electrode slurry, and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based lithium ion battery negative electrode slurry, a preparation method and application thereof. A preparation method of a silicon-based lithium ion battery cathode slurry comprises the following steps of S1, dissolving a binder in deionized water, heating and stirring to form a uniform transparent binder solution, S2, dissolving fluorine-containing metal salt in the deionized water, preparing a fluorine-containing metal salt solution, mixing with the binder solution, adding a silicon-based active material and a conductive agent, and stirring uniformly to obtain the silicon-based lithium ion battery cathode slurry, wherein the binder comprises sodium carboxymethyl cellulose. The invention obviously improves the cycle stability and the multiplying power performance of the battery by adding the fluorine-containing metal salt.

Inventors

• ZHOU CHENGGANG
• ZENG DANLI
• GAO QIANG
• HAN BO
• TONG XIN
• BI YONGQI
• Yang Qijiao
• Ren Zeqing
• SUN YAQI
• Hua Huiling
• LI PINGYANG
• FAN XUEQUAN

Assignees

• 中国地质大学（武汉）

Dates

Publication Date

20260512

Application Date

20260413

Claims (10)

1. 1. The preparation method of the silicon-based lithium ion battery negative electrode slurry is characterized by comprising the following steps of: s1, dissolving a binder in deionized water, heating and stirring to form a uniform transparent binder solution; s2, dissolving fluorine-containing metal salt in deionized water, preparing fluorine-containing metal salt solution, mixing with the binder solution, adding a silicon-based active material and a conductive agent, and uniformly stirring to obtain the silicon-based lithium ion battery cathode slurry; the binder comprises sodium carboxymethyl cellulose.
2. 2. The method of claim 1, wherein the fluorine-containing metal salt is one or more of sodium fluosilicate, potassium fluosilicate, magnesium fluosilicate, zinc fluosilicate, potassium fluoaluminate, sodium fluoaluminate, potassium fluozirconate, sodium fluozirconate, ammonium fluotitanate, potassium fluotitanate, sodium fluotitanate, barium magnesium fluoride, barium zinc fluoride.
3. 3. The method of claim 1, wherein the mass of the fluorine-containing metal salt is 0.5% -2% of the sum of the mass of the fluorine-containing metal salt, the binder, the silicon-based active material and the conductive agent.
4. 4. The method according to claim 1, wherein in the negative electrode slurry, the silicon-based active material, the binder, and the fluorine-containing metal salt=60:20:20-X, and X has a value of 0.5 to 2.
5. 5. The method of claim 1, wherein the binder solution in step S1 has a concentration of 2%.
6. 6. The preparation method according to claim 1, wherein the mass concentration of the fluorine-containing metal salt solution in the step S2 is 0.2% -10%.
7. 7. The method of claim 1, wherein the binder further comprises polyacrylic acid, sodium carboxymethyl cellulose, and polyacrylic acid in a mass ratio of 2:1.
8. 8. The preparation method of claim 1, wherein in the step S2, stirring is performed at 40-90 ℃ for 12-24 hours, the silicon-based active material is nano silicon, micro silicon, silicon carbon or silicon oxygen, and the conductive agent is Super P, acetylene black or carbon nano tube.
9. 9. A silicon-based lithium ion battery negative electrode slurry prepared by the preparation method of any one of claims 1-8.
10. 10. A silicon-based lithium ion battery comprising a silicon-based negative electrode sheet made from the negative electrode slurry of claim 9.

Description

Silicon-based lithium ion battery negative electrode slurry, and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based lithium ion battery negative electrode slurry, a preparation method and application thereof. Background With the rapid development of electric vehicles and energy storage systems, lithium ion batteries are increasingly demanding in terms of energy density and cycling stability. The theoretical capacity of the traditional graphite cathode (G) is 372 mAh/G only, and the development requirement of the next generation of high-energy-density batteries cannot be met. Silicon-based negative electrode becomes the most potential substitute material due to the ultrahigh theoretical capacity of 4200 mAh/g, low working voltage and environmental friendliness. However, commercialization of silicon-based negative electrodes faces serious challenges in that 300% volume expansion during lithiation may lead to cracking of electrode structure, falling of active materials, and repeated breakage and regeneration of Solid Electrolyte Interface (SEI) films. The process continues to consume active lithium and electrolyte, resulting in increased SEI film thickness, increased lithium ion transport resistance, and eventually a rapid decay in battery capacity. The existing improvement strategies comprise structural optimization, composite system construction, binder optimization and the like, but have the problems of complex process, higher cost, poor compatibility and the like. In the prior art, the external regulation and control of electrolyte are relied on, and accurate construction of the SEI film is difficult to realize from the inside of the electrode. There is a need to develop a negative electrode slurry system capable of fundamentally improving the stability of an SEI film, and forming the SEI film with compact structure and excellent ion conductivity through synergistic effect, so as to solve the problem of volume expansion of a silicon-based negative electrode. Disclosure of Invention The invention aims at providing a silicon-based lithium ion battery anode slurry, a preparation method and application thereof, aiming at the defects in the prior art. Starting from the formation process of regulating and controlling the SEI film inside the electrode, the preparation process is optimized to meet the industrial requirement, the limitation of the traditional external regulation and control depending on electrolyte is broken through, and the fluorine-containing metal salt is directly introduced into the negative electrode slurry system. Solves the problems of SEI film damage, capacity attenuation and the like caused by the volume expansion of the silicon-based anode. The first object of the invention is to provide a preparation method of a silicon-based lithium ion battery anode slurry, which comprises the following steps: s1, dissolving a binder in deionized water, heating and stirring to form a uniform transparent binder solution; s2, dissolving fluorine-containing metal salt in deionized water, preparing fluorine-containing metal salt solution, mixing with the binder solution, adding a silicon-based active material and a conductive agent, and uniformly stirring to obtain the silicon-based lithium ion battery cathode slurry; the binder comprises sodium carboxymethyl cellulose. Further, the fluorine-containing metal salt is one or more of sodium fluosilicate, potassium fluosilicate, magnesium fluosilicate, zinc fluosilicate, potassium fluoaluminate, sodium fluoaluminate, potassium fluozirconate, sodium fluozirconate, ammonium fluotitanate, potassium fluotitanate, sodium fluotitanate, barium magnesium fluoride and barium zinc fluoride. Further, the mass of the fluorine-containing metal salt is 0.5% -2% of the sum of the mass of the fluorine-containing metal salt, the mass of the binder, the mass of the silicon-based active material and the mass of the conductive agent. Further, in the negative electrode slurry, the silicon-based active material comprises a conductive agent, a binder and fluorine-containing metal salt=60:20:20-X, wherein the value of X is 0.5-2. Further, the concentration of the binder solution of step S1 is 2%. Further, the mass concentration of the fluorine-containing metal salt solution in the step S2 is 0.2% -10%. Further, the binder also comprises polyacrylic acid, and the mass ratio of sodium carboxymethyl cellulose to polyacrylic acid is 2:1. Further, in the step S2, stirring is performed at 40-90 ℃ for 12-24 hours. Further, the silicon-based active material is nano silicon, micro silicon, silicon carbon or silicon oxygen, and the conductive agent is SuperP, acetylene black or carbon nano tube. The second object of the invention is to provide a silicon-based lithium ion battery anode slurry prepared by the preparation method. The third object of the invention is to provide a silicon