CN-119799223-B - Chitosan water-based binder for silicon negative electrode of lithium ion battery and preparation method thereof

Abstract

The invention belongs to the field of binders, and particularly relates to a chitosan water-based binder for a silicon negative electrode of a lithium ion battery and a preparation method thereof. The preparation raw materials of the chitosan water-based adhesive for the silicon negative electrode of the lithium ion battery comprise chitosan, acrylic acid monomer, acrylic acid polyol ester, a pH regulator, an initiator and deionized water, wherein the mass ratio of the chitosan to the acrylic acid monomer to the acrylic acid polyol ester is (10-15) (5-10) (1-3). According to the invention, the acrylic acid monomer and the acrylic acid polyol ester are used for modifying chitosan, and the prepared aqueous binder has excellent adhesive property, the peel strength can reach more than 12N/m, and the aqueous binder is particularly suitable for silicon cathodes of lithium ion batteries.

Inventors

• YU FANGMIAO
• WANG JIE
• ZHOU CHANGJI
• ZHANG CHENCHUN
• XU XIA
• ZHOU HUI
• SHAO HANQI

Assignees

• 浙江中科立德新材料有限公司

Dates

Publication Date

20260512

Application Date

20250313

Claims (7)

1. 1. The chitosan water-based binder for the silicon negative electrode of the lithium ion battery is characterized by comprising the following raw materials of chitosan, acrylic acid monomer, acrylic acid polyol ester, pH regulator, initiator and deionized water; the mass ratio of the chitosan to the acrylic acid monomer to the acrylic acid polyol ester to the deionized water is (10-15)/(5-10)/(1-3)/(72-84); The acrylic polyol ester comprises one or more of pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, glycerol triacrylate and glycerol triacrylate; The acrylic acid monomer comprises acrylic acid and/or methacrylic acid; The initiator is a peroxy initiator; the preparation method of the chitosan water-based binder for the silicon negative electrode of the lithium ion battery is characterized by comprising the following steps of: s1, adding chitosan and acrylic acid monomers into deionized water, stirring until the chitosan is completely dissolved, then adding acrylic acid polyol ester and an initiator, and introducing inert gas of 30-60 min; s2, after the reaction is finished, the system is reduced to 20-30 ℃, the pH regulator is used for neutralizing the system to 6.5-7.5, deionized water is used for diluting until the solid content is 3-8%, and the chitosan water-based binder for the silicon negative electrode of the lithium ion battery is obtained after uniform stirring.
2. 2. The aqueous chitosan binder for lithium ion battery silicon negative electrode according to claim 1, wherein the deacetylation degree of chitosan is more than 85%.
3. 3. The chitosan aqueous binder for the silicon negative electrode of the lithium ion battery according to claim 1, wherein the peroxy initiator comprises one or more of ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, tert-butyl peroxybenzoate, cumene hydroperoxide and tert-butyl hydroperoxide.
4. 4. The aqueous chitosan binder for silicon negative electrodes of lithium ion batteries according to claim 1, wherein the pH regulator comprises one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, sodium bicarbonate aqueous solution and ammonia water.
5. 5. The aqueous chitosan binder for lithium ion battery silicon negative electrode according to claim 4, wherein the mass concentration of the aqueous sodium hydroxide solution is 1-3 wt%.
6. 6. The aqueous chitosan binder for lithium ion battery silicon negative electrode according to claim 1, wherein the inert gas comprises nitrogen.
7. 7. The aqueous chitosan binder for lithium ion battery silicon negative electrode according to claim 1, wherein the polymerization reaction time in the step S1 is 5-8h.

Description

Chitosan water-based binder for silicon negative electrode of lithium ion battery and preparation method thereof Technical Field The invention belongs to the field of binders, and particularly relates to a chitosan water-based binder for a silicon negative electrode of a lithium ion battery and a preparation method thereof. Background Lithium Ion Batteries (LiBs) are widely used in electric vehicles, portable electronic devices, and large energy storage systems due to their high energy density characteristics. Among them, the silicon anode is regarded as a key material for improving the performance of the lithium ion battery. Compared with the graphite cathode widely used at present, the theoretical specific capacity of the silicon cathode is far more than that of graphite by a plurality of times, so that the silicon cathode can store more energy under the same weight or volume, and the cruising ability of the battery is further improved. In addition, silicon is used as an element with abundant reserves in the crust, so that the source is wide, the cost is low, and the production cost of the battery can be effectively reduced by using the silicon cathode. Meanwhile, the low potential characteristic of the silicon negative electrode enables the battery to release more energy in the charging and discharging process, so that the overall energy density of the battery is further improved. However, silicon negative electrodes undergo severe volume expansion (up to 300%) of silicon particles during lithiation, which may lead to destruction of the electrode structure, such as crack formation, active material shedding, etc. These problems not only reduce the cycling stability of the battery and shorten the service life of the battery, but may also cause safety problems. Therefore, how to effectively stabilize the volume change of the silicon anode, maintain the structural integrity of the electrode, and selecting a proper binder is the key point of current research. The silicon negative electrode binder needs to have high strength and high toughness, and can provide effective support and buffering when the volume of silicon particles changes, preventing the damage of the electrode structure. Meanwhile, the binder also needs to have good electrochemical stability so as to avoid side reactions in the charge and discharge processes of the battery and influence the performance of the battery. In addition, good compatibility with the silicon anode material is also critical to ensure binder stability. In recent years, various new binder materials have been developed, such as polymer-based binders, inorganic nanoparticle composite binders, and smart binders having a self-repairing function. For example, chinese patent CN116072878B discloses a binder for an electrode, which is prepared from chitosan, butyl acrylate and methyl methacrylate, and although the binder has high binding strength, an aqueous acetic acid solution is required in the preparation process, and butyl acrylate and methyl methacrylate are mainly oily substances, so that it is difficult to stably work in an aqueous environment. Therefore, the development of the aqueous adhesive for the silicon negative electrode, which can stably work in an aqueous environment and has excellent adhesive performance, has important research value and application prospect. Disclosure of Invention In order to solve the technical problems, the first aspect of the invention provides a chitosan water-based binder for a silicon negative electrode of a lithium ion battery, which is prepared from chitosan, an acrylic acid monomer, an acrylic acid polyol ester, a pH regulator, an initiator and deionized water. As a practical case, the mass ratio of the chitosan, the acrylic acid monomer, the acrylic acid polyol ester and the deionized water is (10-15): (5-10): (1-3): (72-84). As a practical case, the chitosan has a degree of deacetylation of more than 85%. Further, the chitosan is special chitosan for industry, and is purchased from Zhejiang gold shell pharmaceutical industry Co. The chitosan, which is a natural polysaccharide substance, has excellent film forming property and cohesiveness, can be tightly combined with a silicon negative electrode material to form a stable structure, effectively reduces the deformation and rupture of the electrode material in the charge and discharge process, and remarkably improves the cycle stability and safety of the battery. The conductivity of the self-contained electrode material can be further enhanced after being compounded with the electrode material, so that the output power and the energy density of the battery are improved, and the performance of the battery is comprehensively optimized. In addition, the chitosan also has good water absorbability and tissue compatibility, is favorable for promoting the compatibility of the electrode and the electrolyte, forms a stable film, effectively blocks the interaction between the solution in the ele