A composite dispersant for lithium ion battery preparation process and its preparation method and application
By using composite dispersants, the problem of uneven dispersion of nanostructured materials during the preparation of lithium-ion batteries was solved, resulting in reduced slurry viscosity, improved production stability, and lower costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN BAITU NEW MATERIAL TECH CO LTD
- Filing Date
- 2025-11-24
- Publication Date
- 2026-06-23
AI Technical Summary
In the current lithium-ion battery manufacturing process, uneven dispersion of nanostructured materials leads to high viscosity, which easily forms physical gels, affecting production stability and cost. Furthermore, the increased viscosity of the slurry can cause blockages in the conveying process.
A composite of amine dispersants and hydrazine dispersants with a weight ratio of (1-3):(1-3) is used, including small molecules of alkanolamines, short-chain diamines and long-chain diamines, as well as small molecules of hydrazine and PEG-grafted hydrazine. A stable adsorption layer is formed through hydrogen bonding, amino adsorption, alkyl chain entanglement and steric barrier, which reduces the viscosity of the slurry and improves the dispersion stability.
It significantly improves the dispersion effect of nanomaterials, reduces slurry viscosity, avoids physical gel formation, ensures the stability and continuity of battery production, and reduces production costs.
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Abstract
Description
Technical Field
[0001] This application relates to the technical field of conductive carbon material dispersion, and in particular to a composite dispersant for use in the preparation process of lithium-ion batteries, its preparation method, and its application. Background Technology
[0002] In the field of lithium-ion battery manufacturing, the dispersion of nanostructured materials and the homogenization process of the cathode are extremely critical steps. With the widespread application of lithium-ion batteries in electronic devices, electric vehicles, and other fields, the requirements for battery performance and manufacturing costs are becoming increasingly stringent. Good dispersion of nanostructured materials helps improve the energy density and charge / discharge performance of batteries, while efficient homogenization processes ensure the stability and consistency of battery production. These are of great significance for promoting the development of the lithium-ion battery industry.
[0003] Currently, the industry primarily uses equipment such as sand mills or high-pressure homogenizers to achieve the exfoliation and dispersion of nanostructured materials. Simultaneously, dispersants such as PVP (polyvinylpyrrolidone), HNBR (hydrogenated nitrile butadiene rubber), PVDF, PEG (polyethylene glycol), PVA (polyvinyl alcohol), CMC (carboxymethyl cellulose), PAN (polyacrylonitrile), and PAA (polyacrylate) are used to prevent secondary agglomeration of nanostructures by utilizing their steric hindrance. In the slurry homogenization step of lithium battery manufacturing, lithium iron phosphate and lithium manganese iron phosphate, with carbon-coated surfaces, serve as the main positive electrode material. They need to be mixed and homogenized with PVDF (polyvinylidene fluoride), conductive carbon, and other materials in NMP at a specific ratio and solid content requirement. This slurry is then uniformly coated onto an aluminum foil current collector to prepare the electrode sheet.
[0004] However, existing methods have significant drawbacks. The enormous forces between nanomaterials (including van der Waals forces, hydrogen bonds, and physical entanglement) result in extremely high viscosity in nanomaterial dispersions, especially with a rapid increase in viscosity after standing, causing considerable inconvenience in practical applications (such as cathode slurry dispersion). Furthermore, the excessively high viscosity leads to low effective content, significantly increasing costs. In the lithium battery slurry process, the large van der Waals forces between nanoscale main materials such as lithium iron phosphate and lithium manganese iron phosphate can easily cause the slurry system to form a physical gel, leading to abnormalities in the coating process in the next step. The pipelines transporting the slurry can also become clogged due to the rapid increase in slurry viscosity after standing, causing significant problems for continuous battery production lines. Summary of the Invention
[0005] To address the aforementioned technical problems, this application provides a composite dispersant for use in the lithium-ion battery manufacturing process, its preparation method, and its application.
[0006] In a first aspect, this application provides a composite dispersant for use in the preparation process of lithium-ion batteries, comprising an amine dispersant and a hydrazine dispersant in a weight ratio of (1-3):(1-3), wherein the amine dispersant includes small molecule alkanolamines, short-chain diamines, and long-chain diamines, the carbon chain length of the short-chain diamines being C2-C5, and the carbon chain length of the long-chain diamines being ≥C6; the hydrazine dispersant includes small molecule hydrazines and PEG-grafted hydrazine; the small amines include at least three of triethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, n-butanolamine, isobutanolamine, diisobutanolamine, tert-butanolamine, and di-tert-butanolamine; the small hydrazines include at least two of hydrazine, cyanoethylhydrazine, methylhydrazine, hydroxymethylhydrazine, ethylhydrazine, hydroxyethylhydrazine, propylhydrazine, hydroxypropylhydrazine, butylhydrazine, and phenylhydrazine; and the PEG-grafted hydrazine is prepared by grafting PEG that has undergone carboxylation and carboxyl activation with hydrazine.
[0007] Preferably, the short-chain diamine includes one or more of ethylenediamine, N,N,N'-trimethyl-1,2-ethylenediamine, and N,N-di(3-aminopropyl)ethylenediamine.
[0008] Preferably, the long-chain diamine includes 1,6-hexanediamine and / or 1,12-dodecanediamine.
[0009] By adopting the above technical solution, this application utilizes a mixture of amine dispersants and hydrazine dispersants in a weight ratio of (1-3):(1-3) to obtain a composite dispersant for use in the lithium-ion battery preparation process. The amine dispersant includes small molecule alkanolamines, short-chain diamines, and long-chain diamines. The small amines include at least three of the following: triethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, n-butanolamine, isobutanolamine, diisobutanolamine, tert-butanolamine, and di-tert-butanolamine. The hydroxyl and amino groups can form hydrogen bonds with polar solvents, while the alkyl chains adsorb onto the surface of the material to be dispersed due to their hydrophobic properties. Furthermore, after adsorption onto the material surface, these small molecule materials can form a spatial barrier through the extension of their molecular chains. The small amines also possess non-covalent modification capabilities and net charge repulsion for carbon nanotube materials, reducing their agglomeration and improving dispersion stability. For lithium iron phosphate materials, they can act as surface coordination agents, enhancing their dispersion. Short-chain diamines include one or more of ethylenediamine, N,N,N'-trimethyl-1,2-ethylenediamine, and N,N-di(3-aminopropyl)ethylenediamine, which can quickly occupy high-energy crystal planes when blended with the material to be dispersed. Long-chain diamines include 1,6-hexanediamine and / or 1,12-dodecanediamine, which can construct a three-dimensional steric hindrance layer through alkyl chain entanglement, thereby reducing the thixotropic index of the slurry.
[0010] Hydrazine dispersants include small hydrazine molecules and PEG-grafted hydrazine. Small hydrazine molecules include at least two of hydrazine, cyanoethyl hydrazine, methyl hydrazine, hydroxymethyl hydrazine, ethyl hydrazine, hydroxyethyl hydrazine, propyl hydrazine, hydroxypropyl hydrazine, butyl hydrazine, and phenylhydrazine. They are rapidly adsorbed onto the material surface through hydrogen bonding, coordination bonds, or electrostatic interactions. However, when used alone, they are prone to insufficient steric hindrance due to their small molecular weight. PEG-grafted hydrazine, on the other hand, is anchored secondary to the hydrazine group and extends the PEG chain, forming a stable adsorption layer with point-to-surface bonding. The two can achieve a good synergistic effect. Compared with the use of small hydrazine molecules alone, they can significantly improve the dispersion effect of carbon nanotube materials. At the same time, the combination of the two can significantly reduce the slurry viscosity of lithium iron phosphate material dispersion systems and increase the solid content.
[0011] Overall, this composite dispersant can promote the dispersion of nanomaterials, reduce and stabilize the viscosity of nanomaterial slurries and homogenized slurries, increase solid content, reduce costs, and prevent the formation of physical gels in the homogenized system, thus ensuring stable and continuous production on the battery production line.
[0012] Preferably, the amine dispersant comprises small molecules of alcohol amines, short-chain diamines, and long-chain diamines in a weight ratio of (6-8):(1-3):1.
[0013] By adopting the above technical solution, this application controls the weight ratio of small amine molecules, short-chain diamines and long-chain diamines to be (6-8):(1-3):1. At this time, the synergistic effect among the three is better. Since the proportion of small amine molecules is more appropriate, it can ensure rapid surface coverage and reduce agglomeration caused by unadsorbed sites. The appropriate proportion of short-chain diamines and long-chain diamines can balance the requirements of anchoring strength and steric hindrance. If the short-chain diamine is excessive, it will cause inter-chain entanglement. If the long-chain diamine is excessive, it will cause the slurry viscosity to increase and hinder ion transport.
[0014] Preferably, the hydrazine dispersant comprises hydrazine small molecules and PEG-grafted hydrazine in a weight ratio of (3-4):1.
[0015] By adopting the above technical solution, this application controls the weight ratio of hydrazine small molecules and PEG-grafted hydrazine to (3-4):1, which improves the dispersion effect of hydrazine dispersant. The higher proportion of hydrazine small molecules ensures rapid surface adsorption and covers the defect sites on the material surface, while the lower proportion of PEG-grafted hydrazine ensures that the slurry viscosity is at a low level. In the dispersion system, hydrazine small molecules preferentially occupy high-energy surface sites, and PEG-grafted hydrazine then combines with the uncovered area through hydrazine groups to form a stable dispersion network.
[0016] Preferably, the method for preparing PEG-grafted hydrazine includes the following steps: blending PEG with succinic anhydride and reacting at 60-70°C for 40-50 h to obtain PEG-COOH; then activating the carboxyl group of PEG-COOH and blending it with hydrazine; and reacting the PEG-COOH with hydrazine at 22-25°C for 12-15 h; and dialysis to remove unreacted hydrazine to obtain PEG-grafted hydrazine.
[0017] Preferably, the carboxyl-activated PEG is blended with hydrazine in a molar ratio of 1:3 for grafting reaction.
[0018] Preferably, the molecular weight of the PEG is ≤1000.
[0019] By adopting the above technical solution, this application uses succinic anhydride to carboxylate PEG, and then uses 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and / or N-hydroxysuccinimide to activate the carboxyl group. Subsequently, it is grafted with hydrazine to obtain PEG-grafted hydrazine. After being added to the dispersion system, PEG-grafted hydrazine will be anchored again through the hydrazine group and extend the PEG chain to form a stable adsorption layer with point-to-surface bonding, thereby improving the dispersion ability of the material to be dispersed.
[0020] Secondly, this application also provides a method for preparing a composite dispersant in the lithium-ion battery manufacturing process, comprising the following steps: blending an amine dispersant and a hydrazine dispersant to obtain a composite dispersant.
[0021] By adopting the above technical solution, amine dispersants and hydrazine dispersants in a weight ratio of (1-3):(1-3) can be compounded into a composite dispersant. In the amine small molecules, the hydroxyl and amino groups can form hydrogen bonds with polar solvents, and the alkyl chains are adsorbed on the surface of the material to be dispersed. The molecular chains extend to form a spatial barrier, which has non-covalent modification and net charge repulsion effect on carbon nanotube materials, reducing agglomeration and improving dispersion stability. It also plays a surface coordination role for lithium iron phosphate materials and improves the degree of dispersion. Short carbon chain diamines can quickly occupy high-energy crystal planes, and long carbon chain diamines can construct a three-dimensional steric hindrance layer through alkyl chain entanglement and reduce the thixotropic index of the slurry. The hydrazine small molecules and PEG-grafted hydrazine are synergistically compounded to increase the dispersion concentration of carbon nanotube materials by more than 200%, reduce the slurry viscosity of the lithium iron phosphate material dispersion system, and increase the solid content.
[0022] Thirdly, this application also provides an application of a composite dispersant in the preparation process of lithium-ion batteries, wherein the ratio of the composite dispersant to the material to be dispersed is (0.1-0.4):100.
[0023] By adopting the above technical solution, the composite dispersant of this application can promote the dispersion of nanomaterials, reduce and stabilize the viscosity of nanomaterial slurry and homogenized slurry, increase solid content, reduce cost, and also prevent the formation of physical gel in the homogenized system, ensuring stable and continuous production of battery production lines. When the composite dispersant is used in combination with the material to be dispersed at a dosage ratio of (0.1-0.4):100, the composite dispersant can better play its role in promoting dispersion and reducing and stabilizing slurry viscosity.
[0024] In summary, this application has the following beneficial technical effects:
[0025] 1. The hydroxyl and amino groups of small amine molecules can form hydrogen bonds with polar solvents, and the alkyl chains adsorb onto the surface of the material to be dispersed. The molecular chains extend to form a spatial barrier, which has a non-covalent modification and net charge repulsion effect on carbon nanotube materials, reducing agglomeration and improving dispersion stability; and can play a surface coordination role on lithium iron phosphate materials, improving the degree of dispersion.
[0026] 2. When short-chain diamines are blended with the material to be dispersed, they can quickly occupy high-energy crystal planes, while long-chain diamines can construct a three-dimensional steric hindrance layer through alkyl chain entanglement, thereby reducing the thixotropic index of the slurry.
[0027] 3. The synergistic combination of hydrazine-based small molecules and PEG-grafted hydrazine increases the dispersion concentration of carbon nanotube materials by more than 200%, reduces the slurry viscosity of lithium iron phosphate material dispersion systems, and increases the solid content. Detailed Implementation
[0028] The present application will be further described in detail below with reference to embodiments and comparative examples.
[0029] Preparation Example 1.1
[0030] The preparation method of PEG-grafted hydrazine includes the following steps:
[0031] 1 mol of PEG-1500 was mixed with 1.5 mol of succinic anhydride and dispersed in 12 L of anhydrous dichloromethane. The mixture was reacted at 70 °C for 40 h to obtain PEG-COOH. Subsequently, 0.9 mol of PEG-COOH was mixed with 1.1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1 mol of N-hydroxysuccinimide and dispersed in 15 L of MES buffer at pH=6. The mixture was subjected to a carboxyl activation reaction at 25 °C for 30 min. Finally, 0.8 mol of carboxyl-activated PEG was mixed with 3 mol of hydrazine and dispersed in 8 L of phosphate buffer at pH=7.4. The mixture was subjected to a grafting reaction at 25 °C for 12 h. Dialysis was performed to remove unreacted hydrazine to obtain PEG-grafted hydrazine.
[0032] Preparation Example 1.2
[0033] The preparation method of PEG-grafted hydrazine includes the following steps:
[0034] 1 mol of PEG-1500 was mixed with 1.5 mol of succinic anhydride and dispersed in 12 L of anhydrous dichloromethane. The mixture was reacted at 60 °C for 50 h to obtain PEG-COOH. Subsequently, 0.9 mol of PEG-COOH was mixed with 1.1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1 mol of N-hydroxysuccinimide and dispersed in 15 L of MES buffer at pH=6. The mixture was subjected to a carboxyl activation reaction at 25 °C for 30 min. Finally, 0.8 mol of carboxyl-activated PEG was mixed with 3 mol of hydrazine and dispersed in 8 L of phosphate buffer at pH=7.4. The mixture was subjected to a grafting reaction at 22 °C for 15 h. Dialysis was performed to remove unreacted hydrazine to obtain PEG-grafted hydrazine.
[0035] Preparation Example 2.1
[0036] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 1.1 in that the amount of hydrazine used is 2.7 mol, while the rest is the same as in Preparation Example 1.1.
[0037] Preparation Example 2.2
[0038] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 1.1 in that the amount of hydrazine used is 2.4 mol, while the rest is the same as in Preparation Example 1.1.
[0039] Preparation Example 2.3
[0040] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 1.1 in that the amount of hydrazine used is 2.0 mol, while the rest is the same as in Preparation Example 1.1.
[0041] Preparation Example 2.4
[0042] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 1.1 in that the amount of hydrazine used is 1.6 mol, while the rest is the same as in Preparation Example 1.1.
[0043] Preparation Example 3.1
[0044] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-2000, while the rest is the same as in Preparation Example 2.2.
[0045] Preparation Example 3.2
[0046] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-3000, while the rest is the same as in Preparation Example 2.2.
[0047] Preparation Example 3.3
[0048] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-1000, while the rest is the same as in Preparation Example 2.2.
[0049] Preparation Example 3.4
[0050] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-800, while the rest is the same as in Preparation Example 2.2.
[0051] Preparation Example 3.5
[0052] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-400, while the rest is the same as in Preparation Example 2.2.
[0053] Preparation Example 3.6
[0054] The preparation method of PEG-grafted hydrazine differs from that of Preparation Example 2.2 in that all PEG-1500 is replaced with PEG-200, while the rest is the same as in Preparation Example 2.2.
[0055] Preparation Example 4
[0056] The preparation method of PEG-grafted hydrazine includes the following steps:
[0057] 1 mol of PEG-800 was mixed with 1.5 mol of succinic anhydride and dispersed in 12 L of anhydrous dichloromethane. The mixture was reacted at 70 °C for 40 h to obtain PEG-COOH. Subsequently, 0.8 mol of PEG-COOH was mixed with 2.4 mol of hydrazine and dispersed in 8 L of phosphate buffer at pH 7.4. The mixture was then subjected to a grafting reaction at 25 °C for 12 h. Dialysis was performed to remove unreacted hydrazine to obtain PEG-grafted hydrazine.
[0058] Example 1.1
[0059] A method for preparing a composite dispersant in the lithium-ion battery manufacturing process includes the following steps: blending 1 mol of an amine dispersant and 3 mol of a hydrazine dispersant to obtain a composite dispersant;
[0060] 1 mol of amine dispersant consists of 0.6 mol of small-molecule alkanolamines, 0.3 mol of short-chain diamines, and 0.1 mol of long-chain diamines;
[0061] 0.6 mol of small amine molecules consisted of 0.3 mol of isopropanolamine, 0.2 mol of isobutanolamine, and 0.1 mol of di-tert-butanolamine;
[0062] 0.3 mol of short-chain diamine is 0.3 mol of N-hydroxyethyl ethylenediamine;
[0063] 0.1 mol of long-chain diamine is equivalent to 0.1 mol of 1,10-decanediamine;
[0064] The 3 mol hydrazine dispersant includes 2.4 mol of small hydrazine molecules and 0.6 mol of PEG-grafted hydrazine prepared in Example 1.1;
[0065] The 2.4 mol of hydrazine small molecules includes 1 mol of hydrazine, 0.5 mol of hydroxyethyl hydrazine, 0.5 mol of ethyl hydrazine, and 0.4 mol of cyanoethyl hydrazine.
[0066] Example 1.2
[0067] A method for preparing a composite dispersant in the lithium-ion battery manufacturing process includes the following steps: mixing 3 mol of an amine dispersant and 1 mol of a hydrazine dispersant to obtain a composite dispersant;
[0068] The 3 mol amine dispersant consists of 2.4 mol of small-molecule alkanolamines, 0.3 mol of short-chain diamines, and 0.3 mol of long-chain diamines.
[0069] The 2.4 mol of small amine molecules consisted of 1 mol of triethanolamine, 0.5 mol of isopropanolamine, 0.5 mol of isobutanolamine, 0.1 mol of tert-butanolamine, and 0.3 mol of di-tert-butanolamine.
[0070] 0.3 mol of short-chain diamine is 0.3 mol of N,N-dimethylethylenediamine;
[0071] 0.3 mol of long-chain diamine is 0.3 mol of 1,10-decanediamine;
[0072] 1 mol of hydrazine dispersant includes 0.75 mol of small hydrazine molecules and 0.25 mol of PEG-grafted hydrazine prepared in Example 1.2;
[0073] The 0.75 mol hydrazine small molecules include 0.5 mol hydrazine and 0.25 mol hydroxyethyl hydrazine.
[0074] Examples 2.1-2.4
[0075] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the PEG-grafted hydrazine obtained in Preparation Example 1.1 is replaced with the PEG-grafted hydrazine obtained in Preparation Examples 2.1-2.4, while the rest is the same as in Example 1.1.
[0076] Examples 3.1-3.6
[0077] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 2.2 in that the PEG-grafted hydrazine obtained in Preparation Example 2.2 is replaced with the PEG-grafted hydrazine obtained in Preparation Examples 3.1-3.6, while the rest is the same as in Example 2.2.
[0078] Example 4
[0079] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 3.4 in that the PEG-grafted hydrazine obtained in Preparation Example 3.4 is replaced with the PEG-grafted hydrazine obtained in Preparation Example 4, while the rest is the same as in Example 3.4.
[0080] Example 5.1
[0081] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the short-chain diamine is 0.1 mol ethylenediamine, 0.1 mol N,N,N'-trimethyl-1,2-ethylenediamine, and 0.1 mol N,N-di(3-aminopropyl)ethylenediamine, while the rest are the same as in Example 1.1.
[0082] Example 5.2
[0083] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the short-chain diamine is 0.2 mol N,N,N'-trimethyl-1,2-ethylenediamine and 0.1 mol N,N-di(3-aminopropyl)ethylenediamine, while the rest are the same as in Example 1.1.
[0084] Example 5.3
[0085] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the short-chain diamine is 0.3 mol ethylenediamine, while the rest is the same as in Example 1.1.
[0086] Example 5.4
[0087] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the short-chain diamine is 0.15 mol ethylenediamine and 0.15 mol N,N,N'-trimethyl-1,2-ethylenediamine, while the rest are the same as in Example 1.1.
[0088] Example 6.1
[0089] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the long-chain diamine is 0.1 mol of 1,6-hexanediamine, while the rest is the same as in Example 1.1.
[0090] Example 6.2
[0091] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the long-chain diamine is 0.1 mol 1,12-dodecanediamine, while the rest is the same as in Example 1.1.
[0092] Example 6.3
[0093] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the long-chain diamine is 0.06 mol of 1,6-hexanediamine and 0.04 mol of 1,12-dodecanediamine, while the rest is the same as in Example 1.1.
[0094] Example 6.4
[0095] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the long-chain diamine is 0.03 mol of 1,6-hexanediamine and 0.07 mol of 1,12-dodecanediamine, while the rest are the same as in Example 1.1.
[0096] Example 6.5
[0097] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the long-chain diamine is 0.08 mol of 1,6-hexanediamine and 0.02 mol of 1,12-dodecanediamine, while the rest is the same as in Example 1.1.
[0098] Example 7.1
[0099] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of small alkanolamine molecules is 0.2 mol, the amount of short-chain diamine is 0.6 mol, and the amount of long-chain diamine is 0.2 mol. The specific composition and proportion of each substance of the small alkanolamine molecules, short-chain diamine, and long-chain diamine remain unchanged, and all other aspects are the same as in Example 1.1.
[0100] Example 7.2
[0101] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of small alkanolamine molecules is 0.9 mol, the amount of short-chain diamine is 0.075 mol, and the amount of long-chain diamine is 0.025 mol. The specific composition and proportion of each substance of the small alkanolamine molecules, short-chain diamine, and long-chain diamine remain unchanged, and all other aspects are the same as in Example 1.1.
[0102] Example 7.3
[0103] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of small alkanolamine molecules is 0.6 mol, the amount of short-chain diamine is 0.2 mol, and the amount of long-chain diamine is 0.2 mol. The specific composition and proportion of each substance of the small alkanolamine molecules, short-chain diamine, and long-chain diamine remain unchanged, and all other aspects are the same as in Example 1.1.
[0104] Example 7.4
[0105] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of small alkanolamine molecules is 0.6 mol, the amount of short-chain diamine is 0.35 mol, and the amount of long-chain diamine is 0.05 mol. The specific composition and proportion of each substance of the small alkanolamine molecules, short-chain diamine, and long-chain diamine remain unchanged, and all other aspects are the same as in Example 1.1.
[0106] Example 8.1
[0107] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of hydrazine small molecules used is 1.5 mol, the amount of PEG-grafted hydrazine obtained in Example 1.1 is 1.5 mol, and the specific composition and proportion of each substance of the hydrazine small molecules remain unchanged, while the rest are the same as in Example 1.1.
[0108] Example 8.2
[0109] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of hydrazine small molecules used is 2.3 mol, while the amount of PEG-grafted hydrazine obtained in Example 1.1 is 0.7 mol. The specific composition and proportion of each substance of the hydrazine small molecules remain unchanged, and the rest are the same as in Example 1.1.
[0110] Example 8.3
[0111] A method for preparing a composite dispersant used in the preparation process of lithium-ion batteries differs from Example 1.1 in that the amount of hydrazine small molecules used is 2.5 mol, while the amount of PEG-grafted hydrazine obtained in Example 1.1 is 0.5 mol. The specific composition and proportion of each substance of the hydrazine small molecules remain unchanged, and the rest are the same as in Example 1.1.
[0112] Comparative Example 1
[0113] The difference from Example 1.1 is that the amine dispersant is 1 mol of small alcohol amine molecules. The specific composition and proportion of each substance of the small alcohol amine molecules remain unchanged, and the rest are the same as in Example 1.1.
[0114] Comparative Example 2
[0115] The difference from Example 1.1 is that the hydrazine dispersant is 3 mol of hydrazine small molecules, the specific composition of the hydrazine small molecules and the proportion of each substance remain unchanged, and the rest are the same as in Example 1.1.
[0116] Comparative Example 3
[0117] The difference from Example 1.1 is that the 0.6 mol of alkanolamine small molecules is 0.3 mol of diethanolamine, 0.2 mol of diisopropanolamine and 0.1 mol of n-butanolamine, and the rest are the same as in Example 1.1.
[0118] Comparative Example 4
[0119] The difference from Example 1.1 is that the 0.6 mol of alkanolamine small molecules is 0.3 mol of n-propanolamine and 0.3 mol of diisobutanolamine, and the rest are the same as in Example 1.1.
[0120] Performance testing
[0121] Preparation of the dispersion system A to be tested: Use commonly available dispersion equipment, such as a dual planetary disperser, or a screw mixer combined with a high-speed disperser. The dispersion medium can be an organic solvent such as NMP (N-methylpyrrolidone), methanol, ethanol, ethylene glycol, isopropanol, DMA (N,N-dimethylacetamide), DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), etc.; conventional dispersants can be commonly used on the market, such as PVP (poly(N-vinylpyrrolidone)) and its modified polymers, PVA (polyvinyl alcohol) and its modified polymers, PAA (polyacrylate) and its modified polymers, PVDF (polyvinylidene fluoride) and its modified polymers, PEG (polyethylene glycol) and its modified polymers, HNBR (hydrogenated nitrile butadiene rubber) and its modified polymers, etc. The specific choice can be based on the combination with the dispersion medium. Based on the above components, the preparation process is as follows: First, the following proportions are used: 3.5 wt% carbon nanotubes with a diameter of 7-15 nm, 0.88 wt% PVP, 0.0875 wt% composite dispersant, and the remainder is NMP dispersion medium. A conventional dispersant is added to the dispersion medium and stirred to dissolve. Then, the substance to be dispersed is added, and after stirring, the composite dispersant of this invention is added to obtain a mixture. The mixture is then pumped to a sand mill, a high-pressure homogenizer, or a ball mill for dispersion. Once the requirements are met, dispersion is stopped and the material is discharged to obtain the dispersion system A to be tested.
[0122] Preparation of the dispersion system B to be tested: Commonly used dispersion equipment, such as a dual planetary disperser, or a screw mixer combined with a high-speed disperser, can be used. The conventional dispersant is PVDF; the materials to be dispersed are lithium iron phosphate and carbon nanotubes; the conductive agent can be conventional conductive carbon black; the dispersion medium is NMP. Based on the above components, the preparation process is as follows: First, the materials are prepared according to the following proportions: 60wt% lithium iron phosphate, 1wt% conductive carbon black, 0.5wt% carbon nanotubes, 1.5wt% PVDF, 0.15wt% composite dispersant, and the remainder is the dispersion medium NMP. Then, PVDF is dissolved in NMP, followed by the addition of conductive carbon black. Under stirring, lithium iron phosphate and carbon nanotubes are added and dispersed, then the composite dispersant is added. Stirring and dispersion continue until the discharge requirements are met, at which point dispersion is stopped and the material is discharged to obtain the dispersion system B to be tested.
[0123] The discharge viscosity of dispersion system A and dispersion system B to be tested was measured separately and recorded as viscosity 1 (cP). Dispersion system A was placed in an indoor environment at a temperature of 25℃ for 7 days and dispersion system B was placed in an indoor environment at a temperature of 25℃ for 24 hours. The viscosity of dispersion system A and dispersion system B after placement was measured separately and recorded as viscosity 2 (cP).
[0124] Calculate the viscosity change rate Δ based on viscosity 1 and viscosity 2, Δ% = (viscosity 2 - viscosity 1) / viscosity 1 × 100%.
[0125] Table 1 Data Record Table
[0126]
[0127] Data Analysis:
[0128] As can be seen from Table 1, the Δ values of the dispersion systems A and B in Examples 1.1-1.2 were 192.6-198.4% and 44.5-45.1%, respectively. This shows that the composite dispersant of this application can promote the dispersion of nanomaterials and reduce and stabilize the viscosity of nanomaterial slurries and homogenates.
[0129] In Examples 2.1-2.4, this application changed the ratio of PEG to hydrazine in the preparation of PEG-grafted hydrazine. The results showed that the test dispersion system A-Δ and test dispersion system B-Δ in Example 2.4 were significantly lower than those in other examples. It can be seen that this application can indeed improve the dispersion ability of PEG-grafted hydrazine and its synergistic effect with hydrazine small molecules by adjusting the ratio of PEG to hydrazine.
[0130] In Examples 3.1-3.6, the molecular weight of PEG was changed. The results showed that the test dispersion systems A-Δ and B-Δ of Examples 3.3-3.6 were significantly lower than those of other examples. It can be seen that by adjusting the molecular weight of PEG, this application can indeed improve the dispersion ability of PEG-grafted hydrazine and its synergistic effect with small hydrazine molecules.
[0131] In Example 4, the carboxyl activation step in the preparation of PEG-grafted hydrazine was removed. The results showed that the test dispersion system A-Δ and the test dispersion system B-Δ were significantly higher than those in Example 1.1. It can be seen that the PEG-grafted hydrazine preparation method of this application can obtain products with better dispersion ability.
[0132] In Examples 5.1-5.4, the composition of the short-chain diamine was adjusted in this application. The results showed that the test dispersion system A-Δ and the test dispersion system B-Δ were significantly lower than those in Example 1.1. It can be seen that the ethylenediamine, N,N,N'-trimethyl-1,2-ethylenediamine and N,N-di(3-aminopropyl)ethylenediamine used in this application can achieve better dispersion effect, and at the same time have a more obvious synergistic effect with the hydrazine dispersant in the system.
[0133] In Examples 6.1-6.5, the composition of the long-chain diamine was adjusted in this application. The results showed that the test dispersion system A-Δ and the test dispersion system B-Δ were significantly lower than those in Example 1.1. It can be seen that the 1,6-hexanediamine and 1,12-dodecanediamine used in this application can achieve better dispersion effect and have a more obvious synergistic effect with the hydrazine dispersant in the system.
[0134] In Examples 7.1-7.2, the proportion of alkanolamine small molecules was adjusted. The results showed that the test dispersion system A-Δ and test dispersion system B-Δ were significantly higher than those in Example 1.1. It can be seen that the proportion of alkanolamine small molecules is more suitable, thus ensuring rapid surface coverage, reducing agglomeration caused by unadsorbed sites, and improving the dispersion effect.
[0135] In Examples 7.3-7.4, the ratio of short-chain diamines to long-chain diamines was adjusted. The results showed that the measured dispersions A-Δ and B-Δ were significantly lower than those in Example 1.1. An appropriate ratio of short-chain diamines to long-chain diamines can balance the requirements of anchoring strength and steric hindrance. If the short-chain diamine is excessive, it will lead to inter-chain entanglement. If the long-chain diamine is excessive, it will lead to an increase in slurry viscosity and hinder ion transport.
[0136] In Examples 8.1-8.3, this application adjusted the ratio of hydrazine small molecules to PEG-grafted hydrazine. The results showed that the test dispersion system A-Δ and test dispersion system B-Δ of Examples 8.1 and 8.3 were significantly higher than those of Examples 1.1 and 8.2. It can be seen that this application improved the dispersion effect of hydrazine dispersant by controlling the weight ratio of hydrazine small molecules to PEG-grafted hydrazine to (3-4):1. The higher proportion of hydrazine small molecules ensures rapid surface adsorption and covers the defect sites on the material surface, while the lower proportion of PEG-grafted hydrazine ensures that the slurry viscosity is at a low level. In the dispersion system, hydrazine small molecules preferentially occupy high-energy surface sites, and PEG-grafted hydrazine then combines with the uncovered areas through hydrazine groups to form a stable dispersion network.
[0137] In Comparative Example 1, short-chain diamines and long-chain diamines were removed in this application. The results showed that the test dispersion system A-Δ and the test dispersion system B-Δ were significantly higher than those in Example 1.1. It can be seen that short-chain diamines can quickly occupy high-energy crystal planes when blended with the material to be dispersed, while long-chain diamines will construct a three-dimensional steric hindrance layer through alkyl chain entanglement, reducing the thixotropic index of the slurry. The two have a good synergistic effect, thus greatly improving the dispersion ability of the composite dispersant.
[0138] In Comparative Example 2, this application removed PEG-grafted hydrazine. The results showed that the test dispersion system A-Δ and test dispersion system B-Δ were significantly higher than those in Example 1.1. It can be seen that PEG-grafted hydrazine can anchor and extend the PEG chain through the hydrazine group to form a stable adsorption layer with point-to-surface combination. It has a good synergistic effect with hydrazine small molecules. Compared with the use of hydrazine small molecules alone, it can significantly improve the dispersion effect of carbon nanotube materials. At the same time, the combination of the two can significantly reduce the slurry viscosity of lithium iron phosphate material dispersion system and increase the solid content.
[0139] In Comparative Examples 3-4, the composition of the small amine molecules in this application was adjusted. The results showed that the test dispersion system A-Δ and the test dispersion system B-Δ were significantly higher than those in Example 1.1. It can be seen that at least three of the following small amine molecules, namely triethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, n-butanolamine, isobutanolamine, diisobutanolamine, tert-butanolamine, and di-tert-butanolamine, have better dispersing ability than other small amine molecules.
[0140] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A composite dispersant for use in the preparation process of lithium-ion batteries, characterized in that, It includes amine dispersants and hydrazine dispersants in a weight ratio of (1-3):(1-3), wherein the amine dispersants include small molecules of alcohol amines, short-chain diamines and long-chain diamines, the carbon chain length of the short-chain diamines is C2-C5, and the carbon chain length of the long-chain diamines is ≥C6; the hydrazine dispersants include small molecules of hydrazine and PEG-grafted hydrazine. Small amine molecules include at least three of the following: triethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, n-butanolamine, isobutanolamine, diisobutanolamine, tert-butanolamine, and di-tert-butanolamine; Hydrazine small molecules include at least two of the following: hydrazine, cyanoethyl hydrazine, methyl hydrazine, hydroxymethyl hydrazine, ethyl hydrazine, hydroxyethyl hydrazine, propyl hydrazine, hydroxypropyl hydrazine, butyl hydrazine, and phenylhydrazine. PEG-grafted hydrazine is prepared by grafting hydrazine onto PEG that has undergone carboxylation and carboxyl activation.
2. The composite dispersant for use in the preparation process of lithium-ion batteries according to claim 1, characterized in that, The short-chain diamine includes one or more of ethylenediamine, N,N,N'-trimethyl-1,2-ethylenediamine, and N,N-di(3-aminopropyl)ethylenediamine.
3. The composite dispersant for use in the preparation process of lithium-ion batteries according to claim 1, characterized in that, The long-chain diamines include 1,6-hexanediamine and / or 1,12-dodecanediamine.
4. The composite dispersant for use in the preparation process of lithium-ion batteries according to claim 1, characterized in that, The amine dispersant comprises small molecules of alcoholic amines, short-chain diamines, and long-chain diamines in a weight ratio of (6-8):(1-3):
1.
5. A composite dispersant for use in the preparation process of lithium-ion batteries according to claim 1, characterized in that, The hydrazine dispersant comprises hydrazine small molecules and PEG-grafted hydrazine in a weight ratio of (3-4):
1.
6. A composite dispersant for use in the preparation process of lithium-ion batteries according to claim 1, characterized in that, The method for preparing the PEG-grafted hydrazine includes the following steps: PEG is blended with succinic anhydride and reacted at 60-70℃ for 40-50h to obtain PEG-COOH. Then, the PEG-COOH is activated by carboxyl groups and blended with hydrazine. The grafting reaction is carried out at 22-25℃ for 12-15h. Unreacted hydrazine is removed by dialysis to obtain PEG-grafted hydrazine.
7. A composite dispersant for use in the preparation process of lithium-ion batteries according to claim 6, characterized in that, The carboxyl-activated PEG was blended with hydrazine at a molar ratio of 1:3 for grafting reaction.
8. A composite dispersant for use in the preparation process of lithium-ion batteries according to claim 6, characterized in that, The molecular weight of the PEG is ≤1000.
9. A method for preparing a composite dispersant for use in the preparation process of lithium-ion batteries according to any one of claims 1-8, characterized in that, The process includes the following steps: blending amine dispersants and hydrazine dispersants to obtain a composite dispersant.
10. The application of the composite dispersant according to any one of claims 1-8 in the preparation process of lithium-ion batteries, characterized in that, The ratio of the composite dispersant to the material to be dispersed is (0.1-0.4):100.