Dispersant for lithium-ion battery slurry

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and relates to a dispersant for a lithium-ion battery slurry. The technical problem to be solved by the present invention is to provide a dispersant with good performance for a lithium-ion battery slurry. The dispersant is prepared from the following components in parts by weight: 46-75 parts of a monomer I, 0.1-15 parts of a monomer II, 23-50 parts of a monomer III, and 0.5-5 parts of a monomer IV, wherein the monomer I comprises an unsaturated acid or an anhydride thereof; the monomer II is an unsaturated hydrophilic monomer; the monomer III is an unsaturated nitrile group monomer; and the monomer IV is an unsaturated functional monomer. The dispersant for a lithium-ion battery slurry of the present invention is formed by polymerizing monomers at a specific ratio; the raw materials thereof are simple and easily available, and the costs thereof are relatively low; the dispersant is present in water in the state of a solution or an aqueous emulsion, and therefore there is no need for pulping, the use amount is low, and the dispersant is fine enough to supply good scrape-coating performance and does not crack at a high temperature and a specified thickness; moreover, the slurry has a good stability, and can greatly improve the adhesive force before and after rolling and enhance the bonding strength.

Description

Dispersants for lithium-ion battery slurries

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to Chinese patent application CN2023117004973, filed on December 12, 2023, and is incorporated herein by reference in its entirety for all other purposes. Technical Field

[0003] The invention relates to a dispersant for lithium ion battery slurry, belonging to the technical field of lithium ion batteries. Background Art

[0004] Lithium-ion batteries offer advantages such as high specific energy, high voltage, long cycle life, excellent safety, rapid charge and discharge, and a wide operating temperature range. They are widely used in electric vehicles, energy storage, electronics, and other technological fields. Electrodes, as key components of lithium-ion batteries, have become a research focus in this field.

[0005] Traditional electrodes primarily consist of a current collector and the electrode material attached to it. Preparation involves adding the electrode active material, binder, and conductive agent to a solvent, stirring to form an electrode slurry. The slurry is then applied to the current collector and dried. To ensure uniform dispersion of the active material and conductive agent, forming a stable slurry for easier coating, a thickening and dispersing agent is often added.

[0006] At present, the most commonly used dispersant in lithium-ion batteries is sodium carboxymethyl cellulose (CMC). Lithium-ion battery slurry generally adopts CMC and styrene-butadiene rubber (SBR) system, which has defects such as excessive CMC dosage, high-temperature thickness cracking, and low peel strength, and needs further improvement.

[0007] The invention patent with application number 202011268232.7 discloses an aqueous thickening dispersant, an aqueous binder and a preparation method for lithium-ion batteries. The dispersant is composed of at least one of an ethylenically unsaturated acid and its anhydride, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated hydrophilic monomer without a carboxyl group, an ethylenically unsaturated hydrophobic monomer, a reactive surfactant, a functional monomer, and an initiator. It can be used in lithium-ion batteries, but its fineness and coating performance are poor, the adhesion is average, and the slurry stability also needs to be further improved.

[0008] Summary of the Invention

[0009] The technical problem solved by the present invention is to provide a dispersant for lithium ion battery slurry with good performance.

[0010] The dispersant for lithium-ion battery slurry of the present invention is made of the following components in parts by weight:

[0011] Monomer I: 46-75 parts;

[0012] Monomer II: 0.1 to 15 parts;

[0013] The third monomer: 23 to 50 parts;

[0014] The fourth monomer: 0.5 to 5 parts;

[0015] Wherein, the first monomer includes an unsaturated acid or an anhydride thereof; the second monomer is an unsaturated hydrophilic monomer; the third monomer is an unsaturated nitrile monomer; and the fourth monomer is an unsaturated functional monomer.

[0016] In some embodiments of the present invention, the unsaturated acid is at least one of maleic acid, itaconic acid, (meth)acrylic acid, acrylic acid, methacrylic acid, allyloxyhydroxypropyl sulfonic acid, vinyl sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, propylene sulfonic acid, methpropylene sulfonic acid, itaconic acid, and maleic acid.

[0017] In some specific embodiments, the first monomer further includes an unsaturated salt monomer, and the unsaturated salt monomer is at least one of acrylate, methacrylate, allyloxyhydroxypropyl sulfonate, vinyl sulfonate, propylene sulfonate, methylpropylene sulfonate, itaconate, and maleate.

[0018] In some embodiments of the present invention, the unsaturated hydrophilic monomer includes at least one of (meth)acrylamide, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, 2-methacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacryloyl, N-hydroxypropylacryloyl, and ethoxyethoxyethyl acrylate.

[0019] In some embodiments of the present invention, the unsaturated nitrile-based monomer includes at least one of acrylonitrile, methacrylonitrile, and ethacrylonitrile.

[0020] In some embodiments of the present invention, the unsaturated functional monomers include (meth) lauric acid ester, (meth) octadecyl acrylate, (meth) acrylate polyethylene glycol lauric acid ester, (meth) acrylate behenyl ester, allyl-containing alkyl alcohol ether sulfate, allyloxy isomeric alcohol ether sulfate ammonium salt, allyloxy isomeric alcohol ether sulfate, vinyl dodecanoate, vinyl hexadecanoate, vinyl octadecanoate, At least one of the following, wherein n is 12 to 22; m ≥ 1.

[0021] In some embodiments of the present invention, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: monomer I: 55-60 parts; monomer II: 2-10 parts; monomer III: 31-38 parts; monomer IV: 1-4 parts. In some preferred embodiments, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: monomer I: 55 parts; monomer II: 9.5 parts; monomer III: 31.7 parts; monomer IV: 3.8 parts.

[0022] In some embodiments of the present invention, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: methacrylic acid: 55-60 parts; methacrylamide: 2-10 parts; acrylonitrile: 31-38 parts; lauric acid ester: 1-4 parts. In a preferred embodiment, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: methacrylic acid: 55 parts; methacrylamide: 9.5 parts; acrylonitrile: 31.7 parts; lauric acid ester: 3.8 parts.

[0023] In one embodiment of the present invention, the dispersant for lithium-ion battery slurry of the present invention is prepared by the following method:

[0024] The monomers and water to be reacted are heated to the reaction temperature under a protective atmosphere, and an initiator is added to initiate the reaction to obtain a solid-liquid mixture, and then the precipitate is taken and neutralized to obtain an aqueous dispersant. The monomers in the reaction are all monomers involved in the reaction, including monomer I, monomer II, monomer III, and monomer IV.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The dispersant for lithium-ion battery slurry of the present invention is prepared by polymerizing an unsaturated acid or its anhydride, an unsaturated hydrophilic monomer, an unsaturated nitrile monomer and an unsaturated functional monomer in a specific ratio. The raw materials of the dispersant are simple and easy to obtain, and the cost is low. The dispersant exists in the form of a solution or an aqueous emulsion in water, does not require slurrying, has a low usage amount, has good fineness and coating performance, does not crack at high temperature, and has good slurry stability. It can greatly improve the adhesion before and after rolling and improve the bonding strength. DETAILED DESCRIPTION

[0027] The dispersant for lithium-ion battery slurry of the present invention is made of the following components in parts by weight:

[0028] Monomer I: 46-75 parts;

[0029] Monomer II: 0.1 to 15 parts;

[0030] The third monomer: 23 to 50 parts;

[0031] The fourth monomer: 0.5 to 5 parts;

[0032] Wherein, the first monomer includes an unsaturated acid or an anhydride thereof; the second monomer is an unsaturated hydrophilic monomer; the third monomer is an unsaturated nitrile monomer; and the fourth monomer is an unsaturated functional monomer.

[0033] The dispersant for lithium-ion battery slurry of the present invention has an acrylic polymer as its main component, which is polymerized by unsaturated acid or its anhydride, unsaturated hydrophilic monomer, unsaturated nitrile monomer and unsaturated functional monomer. The dispersant is an aqueous glue, exists in the form of solution or aqueous emulsion in water, does not require beating, and has low usage, good bonding performance, good fineness scraping performance, no cracking of the thickness at high temperature, and good slurry stability.

[0034] The unsaturated acid or its anhydride described in the present invention is an unsaturated acid or an anhydride of an unsaturated acid. Ethylenically unsaturated acids or their anhydrides commonly used in the art are suitable for use in the present invention. In some embodiments of the present invention, the unsaturated acid is at least one of maleic acid, itaconic acid, and (meth)acrylic acid. It is at least one of acrylic acid, methacrylic acid, allyloxyhydroxypropylsulfonic acid, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, propylenesulfonic acid, methpropylenesulfonic acid, itaconic acid, and maleic acid. The anhydride of the unsaturated acid is an anhydride of the above-mentioned acid.

[0035] In some specific embodiments, the first monomer further includes an unsaturated salt monomer, and the unsaturated salt monomer is at least one of acrylate, methacrylate, allyloxyhydroxypropyl sulfonate, vinyl sulfonate, propylene sulfonate, methylpropylene sulfonate, itaconate, and maleate.

[0036] In some embodiments of the present invention, the unsaturated hydrophilic monomer includes at least one of (meth)acrylamide, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, 2-methacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacryloyl, N-hydroxypropylacryloyl, and ethoxyethoxyethyl acrylate.

[0037] In some embodiments of the present invention, the unsaturated nitrile-based monomer includes at least one of acrylonitrile, methacrylonitrile, and ethacrylonitrile.

[0038] In some embodiments of the present invention, the unsaturated functional monomers include (meth) lauric acid ester, (meth) octadecyl acrylate, (meth) acrylate polyethylene glycol lauric acid ester, (meth) acrylate behenyl ester, allyl-containing alkyl alcohol ether sulfate, allyloxy isomeric alcohol ether sulfate ammonium salt, allyloxy isomeric alcohol ether sulfate, vinyl dodecanoate, vinyl hexadecanoate, vinyl octadecanoate, (n is 12 to 22; m ≥ 1), (n is 12 to 22; m ≥ 1).

[0039] The "(meth)acrylic..." mentioned in the present invention means "acrylic..." or "methacrylic...", for example, (meth)acrylamide is acrylamide or methacrylamide, hydroxyethyl (meth)acrylate is hydroxyethyl acrylate or hydroxyethyl methacrylate, and octadecyl (meth)acrylate is octadecyl acrylate or octadecyl methacrylate.

[0040] In some embodiments of the present invention, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: monomer I: 55-60 parts; monomer II: 2-10 parts; monomer III: 31-38 parts; monomer IV: 1-4 parts. In some preferred embodiments, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: monomer I: 55 parts; monomer II: 9.5 parts; monomer III: 31.7 parts; monomer IV: 3.8 parts.

[0041] In some embodiments of the present invention, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: methacrylic acid: 55-60 parts; methacrylamide: 2-10 parts; acrylonitrile: 31-38 parts; lauric acid ester: 1-4 parts. In a preferred embodiment, the dispersant for lithium-ion battery slurry is made from the following components in parts by weight: methacrylic acid: 55 parts; methacrylamide: 9.5 parts; acrylonitrile: 31.7 parts; lauric acid ester: 3.8 parts.

[0042] The dispersant for lithium-ion battery slurry of the present invention can be obtained by polymerization using conventional polymerization methods in the art. In one embodiment of the present invention, it is prepared by the following method:

[0043] The monomers and water to be reacted are heated to the reaction temperature under a protective atmosphere, and an initiator is added to initiate the reaction to obtain a solid-liquid mixture, and then the precipitate is taken and neutralized to obtain an aqueous dispersant. The monomers in the reaction are all monomers involved in the reaction, including monomer I, monomer II, monomer III, and monomer IV.

[0044] The specific embodiments of the present invention are further described below in conjunction with examples, but the present invention is not limited to the scope of the examples.

[0045] Example 1

[0046] The polymerization monomers in this embodiment are: 46.5 parts of maleic acid, 5 parts of acrylamide, 43.5 parts of acrylonitrile, and 5 parts of lauric methacrylate.

[0047] The preparation method is:

[0048] 400 parts of deionized water were added to a reactor, stirred at 300 r / min, and nitrogen was introduced for protection. The temperature was raised to 75°C. 0.5 parts of ammonium persulfate were added, and simultaneously, 1 drop of a mixed monomer of 46.5 parts of maleic acid and 5 parts of lauric methacrylate, and 2 drops of a mixed monomer of 5 parts of acrylamide and 43.5 parts of acrylonitrile were added to the reactor. After reacting for 4 hours, the temperature was raised to 80°C and maintained for 3 hours to obtain a solid-liquid mixture.

[0049] The precipitate was taken out from the solid-liquid mixture, neutralized with sodium hydroxide, the pH was adjusted to 7.0, and deionized water was added to adjust the solid content to 6 wt % to obtain a translucent aqueous dispersant.

[0050] Examples 2 to 9

[0051] The method of Example 1 was used to adjust the formula of the polymerization monomer according to Table 1 to obtain a dispersant for lithium-ion battery slurry.

[0052] Comparative Examples 1-2

[0053] The method of Example 1 was used to adjust the formula of the polymerization monomer according to Table 1 to obtain a dispersant for lithium-ion battery slurry.

[0054] Table 1

[0055] Comparative Example 3

[0056] The polymerization monomers of this comparative example are: 29.5 parts of methacrylic acid, 45 parts of methacrylonitrile, 15 parts of acrylamide, 5 parts of ethyl acrylate, 3 parts of double-bond-containing bisalkyl sulfosuccinate salt (M-30S), and 2 parts of methacrylic acid polyether alkyl end-capped ester (BOM60).

[0057] The polymerization method is the same as in Example 1.

[0058] The dispersants of Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to the following relevant performance tests:

[0059] 1. Viscosity measurement

[0060] The dispersants of Examples 1 to 9 and Comparative Examples 1 to 3 were dispersed in water to prepare dispersant solutions or aqueous emulsions with a solid content of 6%. The viscosities of the solutions or aqueous emulsions were measured. The results are shown in Table 2.

[0061] Viscosity test method: Turn on the power of the thermostatic bath, raise the water temperature in the thermostatic bath to 25°C and keep the temperature constant (the temperature fluctuation of the thermostatic water shall not exceed ±0.2°C). Pour about 320g of the test sample into a clean and dry measuring cup (about 30mm from the top of the cup), insert a rubber stopper with a thermometer to seal it, and then place it in a thermostatic bath to keep the temperature constant at 25°C (stir once every 5 minutes to make the concentration and temperature in the sample uniform), and then keep the temperature constant for 10 minutes before testing. Use a digital viscometer to test the viscosity of the sample that has been kept at a constant temperature of 25°C (refer to the DV2TLV digital viscometer manual for specific operating methods). Test parameter setting:

[0062] Rotor: No63#; Speed: 6RPM (select the appropriate speed according to different viscosity ranges).

[0063] Test conditions: test time = 3 min, data collection duration = 2 min.

[0064] Data collection method: single point averaging.

[0065] Table 2

[0066] 2. Fineness of scraping performance

[0067] Preparation of negative electrode slurry: The dispersant, binder SBR, conductive agent Super-P, and graphite from Examples 1-9 or Comparative Examples 1-3 were mixed to obtain negative electrode slurry. Commercially available CMC2200 and CMC2300 were used as controls. The weight percentages of dispersant and SBR in the negative electrode slurry are shown in Table 3. The conductive agent was used in an amount of 1.0 part, with the remainder being graphite.

[0068] Place 5 mL of negative electrode slurry on the maximum scale mark on a stainless steel fineness gauge. Place a hand-held scraper at the maximum scale mark (the edge of the slurry), ensuring that the scraper is in perpendicular contact with the surface. Within 3 seconds, move the scraper from the maximum scale mark to the minimum scale mark. Immediately observe the fineness gauge where particles are uniformly visible and record the number. A value of 10-15 microns is considered excellent, 15-20 microns is considered medium, and 20 microns or more with visible particles is considered poor. The results are shown in Table 3.

[0069] 3. Slurry stability

[0070] Filter 500g of the negative electrode slurry through a 120-mesh sieve and place it in a 500mL beaker. Test the solids content of the surface slurry, denoted as m0. Then seal the slurry and store it in an ambient temperature of 25°C and a humidity of 40-60%. After 24 hours, test the solids content of the surface slurry again, denoted as m24.

[0071] Slurry stability = (m24-m0) / m0*100, the results are shown in Table 3.

[0072] 4. Adhesion

[0073] After filtering the negative electrode slurry through a 120-mesh screen, apply it on copper foil. Bake it in an oven at 110°C for 10 minutes, then transfer it to a drying room (temperature 25°C, humidity 20-30% RH). Control the single-side density of the electrode to be between 120-130 g / m 2 The electrode sheets before and after rolling were cut into 15.0 cm * 4.0 cm size test samples. The coated side was attached to the test bench with double-sided tape, and the current collector was attached with 3M tape. The tensile test machine was controlled at a tensile rate of 100 mm / min and the current collector was peeled off at 180°. The adhesion before and after rolling was obtained. The results are shown in Table 3.

[0074] Table 3

[0075] As can be seen, the dispersant for lithium battery slurry of the present invention has a blade coating fineness comparable to that of commercially available CMC and is superior to that of Comparative Examples 1 and 2. Its slurry stability and bonding strength are both superior to those of Comparative Examples 1 to 3, indicating that the specific composition and ratio of acrylic polymer can improve the stability and bonding strength of the slurry.

Claims

1. A dispersant for lithium-ion battery slurry, characterized in that: Made from the following components in parts by weight: Monomer I: 46-75 parts; Monomer II: 0.1 to 15 parts; The third monomer: 23-50 parts; The fourth monomer: 0.5 to 5 parts; Among them, the first monomer includes an unsaturated acid or its anhydride; the second monomer is an unsaturated hydrophilic monomer; the third monomer is an unsaturated nitrile monomer, and the fourth monomer is an unsaturated functional monomer.

2. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The unsaturated acid is at least one of maleic acid, itaconic acid, (meth)acrylic acid, acrylic acid, methacrylic acid, allyloxyhydroxypropyl sulfonic acid, vinyl sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, propylene sulfonic acid, methpropylene sulfonic acid, itaconic acid, and maleic acid.

3. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The first monomer also includes an unsaturated salt monomer, and the unsaturated salt monomer is at least one of acrylate, methacrylate, allyloxyhydroxypropyl sulfonate, vinyl sulfonate, propylene sulfonate, methyl propylene sulfonate, itaconate, and maleate.

4. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The unsaturated hydrophilic monomer includes at least one of (meth)acrylamide, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, 2-methylacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, N-hydroxypropylacrylamide, and ethoxyethoxyethyl acrylate.

5. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The unsaturated nitrile-based monomer includes at least one of acrylonitrile, methacrylonitrile and ethacrylonitrile.

6. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The unsaturated functional monomers include (meth) lauric acid ester, (meth) octadecyl acrylate, (meth) acrylate polyethylene glycol lauric acid ester, (meth) acrylate behenyl ester, allyl alkyl alcohol ether sulfate, allyloxy isomeric alcohol ether sulfate ammonium salt, allyloxy isomeric alcohol ether sulfate, dodecanoic acid vinyl ester, hexadecanoic acid vinyl ester, octadecanoic acid vinyl ester, At least one of the following, wherein n is 12 to 22; m ≥ 1.

7. The dispersant for lithium-ion battery slurry according to claim 1, characterized in that: The invention is prepared from the following components in parts by weight: 55 to 60 parts of the first monomer; 2 to 10 parts of the second monomer; 31 to 38 parts of the third monomer; and 1 to 4 parts of the fourth monomer.

8. The dispersant for lithium-ion battery slurry according to claim 7, characterized in that: It is made of the following components in parts by weight: 55 parts of monomer I; 9.5 parts of monomer II; 31.7 parts of monomer III; and 3.8 parts of monomer IV.

9. [Corrected 27.11.2024 in accordance with Rule 26] The dispersant for lithium-ion battery slurry according to claim 7, characterized in that: The invention is prepared from the following components in parts by weight: 55 to 60 parts of methacrylic acid; 2 to 10 parts of methacrylamide; 31 to 38 parts of acrylonitrile; and 1 to 4 parts of lauric acid ester.

10. The dispersant for lithium-ion battery slurry according to claim 9, characterized in that: It is made of the following components in parts by weight: 55 parts of methacrylic acid; 9.5 parts of methacrylamide; 31.7 parts of acrylonitrile; and 3.8 parts of lauric acid ester.

11. The dispersant for lithium ion battery slurry according to claim 1, characterized in that: The preparation method of the dispersant comprises the following steps: heating the reacted monomers and water to the reaction temperature under a protective atmosphere, adding an initiator to initiate the reaction to obtain a solid-liquid mixture, and then taking a precipitate and neutralizing to obtain an aqueous dispersant.

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