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CN-122011975-A - Force-sensitive self-reinforced adhesive for silicon-based negative electrode of lithium ion battery, and preparation method and application thereof

CN122011975ACN 122011975 ACN122011975 ACN 122011975ACN-122011975-A

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly provides a force-sensitive self-reinforced adhesive for a silicon-based negative electrode of a lithium ion battery, and a preparation method and application thereof. The force-sensitive self-reinforced adhesive comprises a basic adhesive polymer and a force-sensitive reinforcing agent, wherein the force-sensitive reinforcing agent is a random copolymer, a block copolymer or a gradient copolymer, the structural general formula of the force-sensitive self-reinforced adhesive can be expressed as a repeated sequence of a functional monomer unit containing a mechanical force-responsive group and a vinyl monomer unit, the weight average molecular weight is 20,000-300,000, the polymerization degree of the functional monomer unit containing the mechanical force-responsive group is 5-200, and the polymerization degree of the vinyl monomer unit is 50-2000. The force-sensitive self-reinforced adhesive responds to the stress change generated by the volume expansion/contraction of the silicon-based material, realizes accurate intervention of stress triggering, and solves the fundamental contradiction of mismatching of the traditional static adhesive network constraint and dynamic volume change.

Inventors

  • LI JIAYI
  • YANG TINGTING
  • Wang Zoubiao

Assignees

  • 湖南智电谷能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260305

Claims (10)

  1. 1. A force-sensitive self-reinforcing binder for a silicon-based negative electrode of a lithium ion battery, which is characterized by comprising a base binding polymer and a force-sensitive reinforcing agent; the force-sensitive reinforcing agent is a random copolymer, a block copolymer or a gradient copolymer, the structural general formula of the force-sensitive reinforcing agent can be expressed as a repeated sequence of a functional monomer unit containing a mechanical force response group and a vinyl monomer unit, and the weight average molecular weight is 20,000-300,000; the polymerization degree of the functional monomer unit containing the mechanical force response group is 5-200, and the polymerization degree of the vinyl monomer unit is 50-2000; the molar ratio of the functional monomer units containing the mechanical force responsive groups to the vinyl monomer units is 1:5 to 1:50; The mechanical force responsive group is a tension ring structure or an oriented force sensitive group; The tension ring structure is at least one of trans-cyclooctane and derivatives thereof, cyclobutane and derivatives thereof, spiro hydrocarbon and derivatives thereof; The directional force-sensitive group is at least one of a diacyl peroxide, a diallyl peroxide, a tert-butyl peroxide acrylate, a dipropylene peroxide phosphate, a 1, 4-butanediol peroxide diacrylate, a tert-butyl methacrylate, an isopropyl acrylate, a divinylbenzene peroxide, an N, N' -bis (acryloyl) cystamine, a bis (methacryloyloxyethyl) disulfide, a divinylbenzene disulfide, a bisacrylamide disulfide, a diethyl dithiodiacrylate, a dithiodiester dimethacrylate, an acryl substituted cystamine derivative.
  2. 2. The force-sensitive self-reinforcing adhesive according to claim 1, wherein the force-sensitive reinforcing agent is selected from the following structural formulas (1) to (3): 、 、 ; Formula (1), formula (2), formula (3); Wherein m is 5-200, n is 50-2000, and the molar ratio of m to n is 1:5-1:50.
  3. 3. The force-sensitive self-reinforcing adhesive according to claim 1, wherein the basic adhesive polymer is at least one of polyacrylic acid, polyacrylamide, sodium alginate, sodium carboxymethyl cellulose, polyvinyl alcohol, polyimide and styrene-butadiene rubber, and the mass of the force-sensitive reinforcing agent is 1-15 wt%.
  4. 4. A method of preparing a force sensitive self-reinforcing adhesive according to any one of claims 1 to 3, comprising the steps of: s1, chemically bonding a target force-sensitive responsive group and a polymerizable functional group by an organic synthesis method to obtain a functional monomer with a mechanical force responsive group; s2, dispersing the functional monomer and the vinyl monomer in a solvent according to a specific proportion, adding an initiator under the protection of inert atmosphere, carrying out free radical copolymerization reaction at 40-80 ℃, and obtaining the force-sensitive reinforcing agent through precipitation, washing, drying and purification; and S3, dispersing the force-sensitive reinforcing agent and the basic binding polymer in deionized water according to a specific mass ratio, and uniformly stirring at room temperature or under a heating condition to obtain a solution containing the force-sensitive self-reinforcing binding agent.
  5. 5. The method of preparing a force sensitive self-reinforcing adhesive according to claim 4, wherein the functional monomer is selected from the following structures: 、 、 。
  6. 6. The method for preparing a force-sensitive self-reinforcing adhesive according to claim 4, wherein in the step S2, the vinyl monomer is at least one of acrylic acid, alkyl acrylate, hydroxyalkyl acrylate, acrylamide, styrene, butadiene and vinyl pyrrolidone, wherein the alkyl is selected from C1-C12 alkyl, the initiator comprises at least one of azodiisoheptanenitrile and benzoyl peroxide, and the solvent comprises at least one of dimethyl sulfoxide, ethanol and tetrahydrofuran.
  7. 7. The method for preparing the force-sensitive self-reinforcing adhesive according to claim 4, wherein the preparation method specifically comprises the following steps: A1, taking trans-cyclooctenol and acryloyl chloride to carry out acyl chloride esterification reaction in the presence of triethylamine to obtain acrylic trans-cyclooctenyl ester; A2, mixing the acrylic acid trans-cyclooctene ester, acrylic acid and tetrahydrofuran, then carrying out chain radical polymerization under the initiation of azodiisoheptonitrile, slowly pouring the reaction solution into diethyl ether to generate white precipitate, washing with diethyl ether and drying to obtain the force-sensitive reinforcing agent with the following structural formula: ; Wherein M is 20 and n is 900, and M w is equal to 185000 as determined by GPC; A3, adding the force-sensitive reinforcing agent and polyacrylic acid into deionized water, and fully stirring until the force-sensitive reinforcing agent and polyacrylic acid are completely dissolved to obtain a uniform solution containing the force-sensitive self-reinforcing adhesive.
  8. 8. The method for preparing the force-sensitive self-reinforcing adhesive according to claim 4, wherein the preparation method specifically comprises the following steps: B1, mixing N, N' -bis (acryloyl) cystamine, hydroxyethyl acrylate and ethanol, then carrying out chain radical polymerization under the initiation of azodiisoheptonitrile, slowly pouring the reaction solution into diethyl ether to generate white precipitate, washing with diethyl ether and drying to obtain the force-sensitive reinforcing agent, wherein the force-sensitive reinforcing agent has the following structural formula: ; Wherein M is 15 and n is 450, M w is about 120000 as determined by GPC; And B2, adding the force-sensitive reinforcing agent and sodium carboxymethyl cellulose into deionized water, and fully stirring until the force-sensitive reinforcing agent and sodium carboxymethyl cellulose are completely dissolved to obtain a uniform solution containing the force-sensitive self-reinforcing adhesive.
  9. 9. The method for preparing the force-sensitive self-reinforcing adhesive according to claim 4, wherein the preparation method specifically comprises the following steps: c1, taking cyclobutyl alcohol and acryloyl chloride to carry out acyl chloride esterification reaction under the protection of hydroquinone monomethyl ether to obtain the cyclobutyl acrylate; C2, mixing the cyclobutyl acrylate, the acrylamide and the dimethyl sulfoxide, then carrying out chain radical polymerization under the initiation of azo-diisoheptonitrile, slowly pouring the reaction liquid into acetone to generate white precipitate, washing with the acetone, and drying to obtain the force-sensitive reinforcing agent, wherein the force-sensitive reinforcing agent has the following structural formula: ; Wherein M is 25 and n is 800, M w is about 95000 as determined by GPC; And C3, adding the force-sensitive reinforcing agent and sodium carboxymethyl cellulose into deionized water, and fully stirring until the force-sensitive reinforcing agent and sodium carboxymethyl cellulose are completely dissolved to obtain a uniform solution containing the force-sensitive self-reinforcing adhesive.
  10. 10. Use of the force-sensitive self-reinforcing adhesive according to any one of claims 1 to 3 or prepared by the preparation method according to any one of claims 4 to 9 in a silicon-based negative electrode of a lithium ion battery.

Description

Force-sensitive self-reinforced adhesive for silicon-based negative electrode of lithium ion battery, and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a force-sensitive self-reinforced adhesive for a silicon-based negative electrode of a lithium ion battery, and a preparation method and application thereof. Background Silicon-based materials are regarded as important options for the negative electrode assembly of the next generation of high energy density lithium ion batteries due to their ultra-high theoretical specific capacity (4200 mAh. G -1), however, the huge volume effect accompanying the charge and discharge will lead to the destruction of the electrode structure and rapid capacity decay, and the use of binders with excellent mechanical properties to solve this problem is a common strategy in academic and enterprise fields. In the research of the prior art, a high-performance adhesive is mainly designed from two aspects, namely, the adhesive force is enhanced, for example, a patent CN119570399A discloses that a strong hydrogen bond is formed between the adhesive rich in vinyl, ester groups, carboxyl groups, hydroxyl groups and the like and the silicon surface, and a mechanical buffer network is constructed, for example, a patent CN119662202A adopts an elastomer or a net structure to relieve stress. These strategies, however, are essentially providing a passive static mechanical constraint whose modulus, toughness and adhesion remain fixed after electrode preparation is complete, while the volumetric effect of the silicon particles is a dynamic heterogeneous process, so that the static binder may not be sufficiently constrained at the early stage of particle expansion, but initiate new stress concentrations due to excessive constraints at the late stage of expansion or in the systolic phase, thus impeding ion transport. In recent years, although research has been directed to self-repairing adhesives, the triggering mechanism is mostly thermal, optical or electrochemical potential, rather than directly in response to mechanical stress itself. Therefore, the development of the binder which can directly sense the mechanical force generated by the silicon particle volume effect and locally adjust the mechanical property of the binder in real time is of great significance in promoting the commercial application of the silicon-based negative electrode. Disclosure of Invention The invention provides a force-sensitive self-reinforcing adhesive for a silicon-based negative electrode of a lithium ion battery, and a preparation method and application thereof, and aims to solve the problem that the existing silicon-based negative electrode adhesive cannot effectively cope with dynamic stress change in the volume expansion/contraction process of a silicon-based material, and finally causes rapid attenuation of battery capacity. In order to achieve the above purpose, the embodiment of the invention provides a force-sensitive self-reinforcing adhesive for a silicon-based negative electrode of a lithium ion battery, and a preparation method and application thereof. The adhesive can flexibly adapt to volume change in the process of volume expansion/contraction of the silicon-based material, adjust the mechanical properties of the adhesive in real time, effectively inhibit cracking and pulverization of electrodes and improve the cycle performance of the lithium ion battery. An aspect of an embodiment of the present invention provides a force-sensitive self-reinforcing adhesive for a silicon-based negative electrode of a lithium ion battery, the force-sensitive self-reinforcing adhesive including a base adhesive polymer and a force-sensitive reinforcing agent; the force-sensitive reinforcing agent is a random copolymer, a block copolymer or a gradient copolymer, the structural general formula of the force-sensitive reinforcing agent can be expressed as a repeated sequence of a functional monomer unit containing a mechanical force response group and a vinyl monomer unit, and the weight average molecular weight is 20,000-300,000; The degree of polymerization of the functional monomer unit containing a mechanical force-responsive group is 5 to 200, the degree of polymerization of the vinyl monomer unit is 50 to 2000, more preferably the degree of polymerization of the functional monomer unit containing a mechanical force-responsive group is 10 to 100, and the degree of polymerization of the vinyl monomer unit is 200 to 1200; The molar ratio of the functional monomer units containing a mechanical force responsive group to the vinyl monomer units is from 1:5 to 1:50, more preferably the molar ratio of the functional monomer units containing a mechanical force responsive group to the vinyl monomer units is from 1:10 to 1:30 The mechanical force responsive groups comprise a tension ring structure or an oriented force sensitiv