A lithium-ion battery negative electrode adhesive and its preparation process

Abstract

This invention discloses a lithium-ion battery anode adhesive and its preparation process, relating to the field of fine chemicals. It comprises the following raw materials in parts by weight: 90-100 parts SBR latex, 20-30 parts polyacrylate latex, 2-5 parts conductive polymer, 0.5-2 parts grafted catalyst, and 2-4 parts CMC. The preparation method is as follows: SBR latex, polyacrylate latex, conductive polymer, and grafted catalyst are stirred in a low-speed homogenizer. CMC is added, and stirring continues until a stable and dispersed emulsion is obtained. The lithium-ion battery anode adhesive provided by this invention can effectively inhibit pulverization and delamination, maintain the integrity of the conductive network, thereby improving the cycle performance of the anode material and extending the battery cycle life.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a lithium-ion battery negative electrode adhesive and its preparation process. Background Technology

[0002] The role of adhesives in electrode materials is to construct an efficient, uniform, and stable conductive / ion transport network, ensuring good electrical contact and uniform current density at the microscale, so that the redox reaction can proceed normally. Adhesives have a great influence on the overall performance of the battery cell, especially the cycle life.

[0003] The high expansion and easy pulverization of novel silicon-based anodes pose new challenges to the performance of adhesives. Traditional adhesives such as CMC / SBR have relatively limited functions, and conventional dispersion methods result in incomplete coverage of the active material by the conductive / adhesive network. When severe silicon particle pulverization occurs, the silicon particles are easily peeled off from the electrode, leading to significant irreversible capacity loss. Furthermore, the poor surface conductivity of silicon-based anodes increases electrode impedance. Therefore, it is necessary to develop an adhesive suitable for anodes to address these issues. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a lithium-ion battery negative electrode adhesive and its preparation process.

[0005] The technical solution of the present invention is as follows:

[0006] A lithium-ion battery negative electrode adhesive comprises the following raw materials in parts by weight: 90-100 parts SBR latex, 20-30 parts polyacrylate latex, 2-5 parts conductive polymer, 0.5-2 parts grafted catalyst, and 2-4 parts CMC.

[0007] As a preferred embodiment of the present invention, the conductive polymer is at least one of polyacetylene, poly(p-phenylene), polythiophene, and polypyrrole.

[0008] As a preferred embodiment of the present invention, the grafting catalyst is at least one of di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, and methyl ethyl ketone peroxide.

[0009] This invention also discloses a preparation process for a lithium-ion battery negative electrode adhesive, which involves stirring SBR latex, polyacrylate latex, conductive polymer, and grafted catalyst in a low-speed homogenizer, adding CMC and continuing to stir until a stable and dispersed emulsion is obtained.

[0010] As a preferred embodiment of the present invention, the stirring speed is 70-120 rpm.

[0011] As a preferred embodiment of the present invention, 0.5-2 parts of composite nanoparticles are also added during the stirring process.

[0012] As a preferred embodiment of the present invention, the method for preparing the composite nanoparticles is as follows:

[0013] Prepare a mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate, add deionized water dropwise, stir at 100-200 rpm, add polystyrene microspheres while stirring, let stand, obtain a precipitate, then dry, wash, and obtain the final product.

[0014] As a preferred embodiment of the present invention, the mass ratio of 3-aminopropyltrimethoxysilane to tetraethyl orthosilicate and polystyrene microspheres is 3-6:1:1.

[0015] As a preferred embodiment of the present invention, the ultrasonic wave is initiated simultaneously with the stirring. The ultrasonic wave is performed in three temperature ranges: 10-15℃, 20-25℃, and 10-15℃. Each temperature range lasts for 10-15 minutes, and the ultrasonic wave frequency is 1-4kHz.

[0016] The beneficial effects of this invention are:

[0017] (1) Traditional SBR latex only serves as a binder, with a single function. The lithium battery negative electrode adhesive provided by this invention can effectively suppress pulverization and peeling, maintain the integrity of the conductive network, thereby improving the cycle performance of the negative electrode material and increasing the battery cycle life.

[0018] (2) The lithium battery negative electrode adhesive provided by this invention incorporates a conductive polymer, which is grafted onto the adhesive molecular chain, making the adhesive itself conductive. Furthermore, the SBR and polyacrylate adhesives form a network structure through cross-linking. The carboxyl groups of the polyacrylate reduce the surface tension of the adhesive, increasing the adhesion of the adhesive molecules to the negative electrode material, thereby suppressing electrode powder shedding and extending cycle life.

[0019] (3) The present invention provides a method for preparing a lithium battery negative electrode adhesive. By adding nanocomposite particles during stirring, i.e., attaching hollow nano-silica to the surface of polymer microspheres, hydrophobic particles with a special structure are formed, reducing the possibility of subsequent negative electrode sheet swelling and powder loss due to water absorption, thereby improving the cycle performance of the electrode sheet. Ultrasonic stirring is carried out in multiple temperature ranges. At lower temperatures, the particles are fragmented and dispersed, while at higher temperatures, the molecular motion is enhanced, resulting in short-range homogeneous dispersion. Combined with the cavitation effect of ultrasound, the dispersion effect is even better. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0021] SBR: Styrene-butadiene rubber latex.

[0022] CMC: Sodium carboxymethyl cellulose.

[0023] Example 1

[0024] A process for preparing a lithium-ion battery negative electrode adhesive involves mixing 100 parts of SBR latex, 30 parts of polyacrylate latex, 3 parts of conductive polymer, and 1 part of grafted catalyst in a low-speed homogenizer for 5 hours, then adding 3 parts of CMC and continuing to mix until a stable and dispersed emulsion is obtained.

[0025] The conductive polymer is polyacetylene. The grafted catalyst is tert-butyl hydroperoxide. The stirring speed is 100 rpm.

[0026] Example 2

[0027] A process for preparing a lithium-ion battery negative electrode adhesive involves mixing 100 parts of SBR latex, 30 parts of polyacrylate latex, 3 parts of conductive polymer, and 1 part of grafted catalyst in a low-speed homogenizer for 5 hours, then adding 3 parts of CMC and continuing to mix until a stable and dispersed emulsion is obtained.

[0028] The conductive polymer is polyacetylene. The grafted catalyst is tert-butyl hydroperoxide. The stirring speed is 100 rpm.

[0029] 0.5 parts of composite nanoparticles were also added during the stirring process.

[0030] The preparation method of the composite nanoparticles is as follows:

[0031] A mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate was prepared, and deionized water was added dropwise. The mixture was stirred at 150 rpm while polystyrene microspheres were added. The mixture was allowed to stand to obtain a precipitate, which was then dried and washed to obtain the final product.

[0032] The mass ratio of 3-aminopropyltrimethoxysilane, tetraethyl orthosilicate, and polystyrene microspheres is 4:1:1.

[0033] The ultrasonic waves are activated simultaneously with the stirring. The ultrasonic waves are conducted in three temperature ranges: 12°C, 25°C, and 15°C. Each temperature range lasts for 15 minutes, and the ultrasonic frequency is 2 kHz.

[0034] Example 3

[0035] A process for preparing a lithium-ion battery negative electrode adhesive involves mixing 100 parts of SBR latex, 30 parts of polyacrylate latex, 3 parts of conductive polymer, and 1 part of grafted catalyst in a low-speed homogenizer for 5 hours, then adding 3 parts of CMC and continuing to mix until a stable and dispersed emulsion is obtained.

[0036] The conductive polymer is polythiophene.

[0037] The grafted catalyst is perperoxide benzoyl peroxide.

[0038] The stirring speed is 100 rpm.

[0039] One part of composite nanoparticles was also added during the stirring process.

[0040] The preparation method of the composite nanoparticles is as follows:

[0041] A mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate was prepared, and deionized water was added dropwise. The mixture was stirred at 150 rpm while polystyrene microspheres were added. The mixture was allowed to stand to obtain a precipitate, which was then dried and washed to obtain the final product.

[0042] The mass ratio of 3-aminopropyltrimethoxysilane, tetraethyl orthosilicate, and polystyrene microspheres is 4:1:1.

[0043] The ultrasonic wave is initiated simultaneously with the stirring. The ultrasonic wave is conducted in three temperature ranges: 12°C, 25°C, and 10°C. Each temperature range lasts for 15 minutes, and the ultrasonic wave frequency is 2 kHz.

[0044] Example 4

[0045] A process for preparing a lithium-ion battery negative electrode adhesive involves mixing 100 parts of SBR latex, 30 parts of polyacrylate latex, 3 parts of conductive polymer, and 1 part of grafted catalyst in a low-speed homogenizer for 5 hours, then adding 3 parts of CMC and continuing to mix until a stable and dispersed emulsion is obtained.

[0046] The conductive polymer is polyacetylene.

[0047] The grafted catalyst is di-tert-butyl peroxide.

[0048] The stirring speed is 100 rpm.

[0049] 1.5 parts of composite nanoparticles were also added during the stirring process.

[0050] The preparation method of the composite nanoparticles is as follows:

[0051] A mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate was prepared, and deionized water was added dropwise. The mixture was stirred at 150 rpm while polystyrene microspheres were added. The mixture was allowed to stand to obtain a precipitate, which was then dried and washed to obtain the final product.

[0052] The mass ratio of 3-aminopropyltrimethoxysilane, tetraethyl orthosilicate, and polystyrene microspheres is 4:1:1.

[0053] The ultrasonic waves are activated simultaneously with the stirring. The ultrasonic waves are conducted in three temperature ranges: 15°C, 20°C, and 10°C. Each temperature range lasts for 12 minutes, and the ultrasonic frequency is 2 kHz.

[0054] Example 5

[0055] A process for preparing a lithium-ion battery negative electrode adhesive involves mixing 100 parts of SBR latex, 30 parts of polyacrylate latex, 3 parts of conductive polymer, and 1 part of grafted catalyst in a low-speed homogenizer for 5 hours, then adding 3 parts of CMC and continuing to mix until a stable and dispersed emulsion is obtained.

[0056] The conductive polymer is polyacetylene.

[0057] The grafted catalyst is di-tert-butyl peroxide.

[0058] The stirring speed is 100 rpm.

[0059] Two parts of composite nanoparticles were also added during the stirring process.

[0060] The preparation method of the composite nanoparticles is as follows:

[0061] A mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate was prepared, and deionized water was added dropwise. The mixture was stirred at 150 rpm while polystyrene microspheres were added. The mixture was allowed to stand to obtain a precipitate, which was then dried and washed to obtain the final product.

[0062] The mass ratio of 3-aminopropyltrimethoxysilane, tetraethyl orthosilicate, and polystyrene microspheres is 4:1:1.

[0063] The ultrasonic waves are activated simultaneously with the stirring. The ultrasonic waves are conducted in three temperature ranges: 12°C, 23°C, and 15°C. Each temperature range lasts for 13 minutes, and the ultrasonic frequency is 2 kHz.

[0064] Comparative Example 1

[0065] Unlike Example 1, no conductive polymer was added.

[0066] Comparative Example 2

[0067] Unlike Example 3, no ultrasound was used during stirring.

[0068] Comparative Example 3

[0069] Unlike Example 3, the stirring was performed at 25°C with an ultrasonic frequency of 2kHz.

[0070] The performance of the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0071] Test method: The adhesive, graphite, conductive carbon black and deionized water of the examples and comparative examples were thoroughly stirred in a mass ratio of 1.5:96.5:1.5:0.5 to obtain a slurry, which was then uniformly coated on a 10μm copper foil. After drying at 80℃, a negative electrode sheet was formed. The peel force and interfacial peel strength of the negative electrode sheet were tested in accordance with the national standard GB / T 2792-2014 "Test method for peel strength of adhesive tape".

[0072] Table 1. Performance test results of the examples and comparative examples.

[0073] Sample Peel force (N) Interfacial peel strength (N / cm) Example 1 4.3 23.7 Example 2 5.2 27.5 Example 3 5.4 28.1 Example 4 5.3 27.6 Example 5 5.1 26.9 Comparative Example 1 3.1 20.3 Comparative Example 2 4.6 25.8 Comparative Example 3 4.8 26.1

[0074] As shown in the table above, the performance of the examples is superior to that of the comparative examples, indicating that the adhesive prepared in the examples has good adhesion, resulting in strong bonding between the electrode and the coating, effectively suppressing powdering and peeling, maintaining the integrity of the conductive network, and thus improving the cycle performance of the negative electrode material. The main reasons are as follows: The examples incorporate conductive polymers, grafting them onto the adhesive molecular chains, making the adhesive itself conductive. Additionally, the SBR and polyacrylate adhesives form a network structure through cross-linking, enhancing the adhesion of adhesive molecules to the negative electrode material, thereby suppressing electrode powder shedding and extending cycle life. Furthermore, by adding nanocomposite particles during stirring—that is, attaching hollow nano-silica to the surface of polymer microspheres—hydrophobic particles with a special structure are formed, reducing the possibility of subsequent negative electrode sheet swelling and powder shedding, thereby improving the electrode's peeling force and cycle performance. Ultrasonic stirring is performed in multiple temperature ranges; at lower temperatures, the dispersion is fragmented, while at higher temperatures, molecular motion is enhanced, resulting in short-range homogeneous dispersion. Combined with the cavitation effect of ultrasound, the dispersion effect is even better. This results in excellent adhesive bonding and improves electrode performance.

[0075] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A process for the preparation of a lithium-ion battery negative electrode adhesive, characterized in that, The lithium ion battery negative electrode adhesive comprises the following raw materials in parts by weight: 90-100 parts of SBR latex, 20-30 parts of polyacrylate latex, 2-5 parts of conductive polymer, 0.5-2 parts of grafting catalyst, and 2-4 parts of CMC; The preparation method is as follows: The SBR latex, the polyacrylate latex, the conductive polymer, and the grafting catalyst are stirred in a low-speed homogenizer, and ultrasonic is started at the same time, the ultrasonic includes three temperature sections of 10-15℃, 20-25℃, and 10-15℃ respectively; each temperature section is performed for 10-15 min, and the ultrasonic wave frequency is 1-4 kHz; after the CMC is added and uniformly stirred, a stable dispersed emulsion is obtained; 0.5-2 parts of composite nanoparticles are also added during the stirring process; The grafting catalyst is at least one of di-tert-butyl peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide, and methyl ethyl ketone peroxide; The preparation method of the composite nanoparticles is as follows: A mixture of 3-aminopropyltrimethoxysilane and tetraethyl orthosilicate is prepared, deionized water is added dropwise, stirring is performed at a speed of 100-200 rpm, polystyrene microspheres are added at the same time, the mixture is left to stand, a precipitate is obtained, and then drying and washing are performed to obtain; The mass ratio of the 3-aminopropyltrimethoxysilane, the tetraethyl orthosilicate, and the polystyrene microspheres is 3-6:1:

1.

2. The manufacturing process according to claim 1, characterized in that, The conductive polymer is at least one of polyacetylene, polyparaphenylene, polythiophene, and polypyrrole.

3. The manufacturing process of claim 1, wherein, The stirring speed in the low-speed homogenizer is 70-120 rpm.