Dynamic viscosity regulation and control additive for sodium-ion battery homogenizing process and preparation method of dynamic viscosity regulation and control additive

Abstract

The invention discloses a dynamic viscosity regulation and control additive for a sodium ion battery homogenizing process and a preparation method thereof. The additive comprises the following components in parts by mass: 40-60 parts of response polymer microspheres, 5-15 parts of a cross-linking agent, 1-5 parts of an initiator, 2-8 parts of a dispersion stabilizer and 20-40 parts of a solvent. The dynamic viscosity regulation and control additive for the sodium-ion battery homogenizing process and the preparation method thereof have the characteristics of good dynamic response performance, high process applicability and excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a dynamic viscosity control additive for sodium-ion battery homogenization process and its preparation method. Background Technology

[0002] In the production of sodium-ion batteries, the slurry mixing process is a crucial step in determining the quality of the electrode sheets. This process requires mixing positive electrode active materials, negative electrode active materials, conductive agents, binders, and solvents to form a slurry with good flowability and stability. However, in actual slurry mixing, the viscosity is easily affected by factors such as the type and ratio of materials, stirring speed, time, and ambient temperature, leading to abnormal changes. When the slurry viscosity is too high, it results in poor flowability, causing problems such as uneven coating thickness and surface roughness during coating; conversely, if the viscosity is too low, sagging is likely to occur during coating, severely affecting the quality of the electrode sheets and subsequent battery performance.

[0003] Currently, the industry typically uses methods such as adding dispersants or adjusting homogenization process parameters to control slurry viscosity, but these methods have significant shortcomings:

[0004] Taking the addition of a dispersant as an example, the following end plate exists:

[0005] First, the dispersant has limited control capabilities, and can only improve the dispersibility and stability of the slurry to a certain extent. It lacks the ability to dynamically control viscosity and cannot respond in real time to changes in environmental parameters such as temperature and pH.

[0006] Second, the limitations of adjusting process parameters: simply increasing the stirring speed or extending the stirring time may lead to excessive material refinement and agglomeration, or even cause deterioration of slurry performance, and cannot fundamentally solve the problem of abnormal viscosity.

[0007] Third, the lack of a dynamic response mechanism: existing additives do not have a coupling effect of viscosity regulation by environmental stimuli, and cannot balance viscosity changes in real time during homogenization, resulting in unstable quality of subsequent processes.

[0008] Therefore, most viscosity-regulating additives in the existing technology are single-response additives, and their structural design and preparation processes have defects. For example, single-temperature-responsive additives cannot cope with viscosity fluctuations caused by changes in the pH value of the slurry; single-pH-responsive additives have poor regulation effects when the temperature changes.

[0009] Furthermore, existing technologies lack dual-response additives with core-shell structures, making it impossible to achieve a synergistic response to both temperature and pH during sodium-ion battery homogenization, resulting in unsatisfactory viscosity control. Summary of the Invention

[0010] The purpose of this invention is to provide a dynamic viscosity control additive for sodium-ion battery homogenization process and its preparation method, which has the characteristics of good dynamic response performance, strong process applicability and excellent electrochemical performance.

[0011] This invention can be achieved through the following technical solutions:

[0012] The present invention relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 40-60 parts of responsive polymer microspheres, 5-15 parts of crosslinking agent, 1-5 parts of initiator, 2-8 parts of dispersing stabilizer, and 20-40 parts of solvent.

[0013] Furthermore, the responsive polymer microspheres have a core-shell structure. The core consists of a thermosensitive polymer with a low critical solution temperature (LCST). When the temperature is below the LCST, the polymer molecular chains are in an extended state in the solvent. When the temperature is above the LCST, the molecular chains contract rapidly, resulting in a smaller volume of the polymer microspheres. The outer shell consists of a pH-sensitive polymer with a large number of carboxyl groups on the molecular chains. In an acidic environment, the carboxyl groups are ionized, and the molecular chains curl up. In an alkaline environment, the carboxyl groups are ionized, and the molecular chains extend.

[0014] Furthermore, the temperature-sensitive polymer is poly(N-isopropylacrylamide) (PNIPAM); the pH-sensitive polymer is polyacrylic acid (PAA).

[0015] Furthermore, the crosslinking agent is N,N-methylenebisacrylamide, which is used to crosslink the polymer molecular chains during the polymerization reaction to form a three-dimensional network structure and improve the stability of the polymer microspheres.

[0016] Furthermore, the initiator is ammonium persulfate, which decomposes during the polymerization reaction to generate free radicals, thus initiating monomer polymerization.

[0017] Furthermore, the dispersant stabilizer is polyvinyl alcohol (PVA), which can be adsorbed on the surface of the polymer microspheres during the formation process to form a protective film, prevent microsphere aggregation, and improve the dispersibility of the microspheres in the solvent.

[0018] Furthermore, the solvent is deionized water, which serves as the medium for the polymerization reaction.

[0019] Another aspect of the present invention is a method for preparing the above-mentioned dynamic viscosity regulating additive, characterized by comprising the following steps:

[0020] S1. Preparation of core polymer: Add thermosensitive polymer monomer, crosslinking agent and initiator to solvent, and under nitrogen protection, control the reaction temperature at 60-70℃ and react for 3-5 hours to obtain thermosensitive polymer solution.

[0021] S2. Preparation of the outer shell polymer: Add the pH-sensitive polymer monomer, crosslinking agent, and initiator to the solvent. Under nitrogen protection, control the reaction temperature at 50-60℃ and react for 2-4 hours to obtain the pH-sensitive polymer solution.

[0022] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution is slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition is complete, stirring is continued for 1-2 hours to form core-shell structured responsive polymer microspheres.

[0023] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0024] Furthermore, in step S3, the high-speed stirring speed is 800-1200 rpm.

[0025] This invention discloses a dynamic viscosity control additive for sodium-ion battery homogenization processes and its preparation method, which has the following beneficial effects:

[0026] First, it exhibits excellent dynamic response performance. The additive of this invention can respond rapidly to changes in the temperature and pH of the slurry. When the slurry temperature increases, leading to an increase in viscosity, the poly(N-isopropylacrylamide) molecular chains of the temperature-sensitive core shrink, reducing the volume of the polymer microspheres and increasing the free volume within the slurry, thereby reducing viscosity. When the pH of the slurry increases due to residual alkaline substances in the cathode material, the polyacrylic acid molecular chains of the pH-sensitive shell expand, altering the volume of the microspheres and their state of existence in the slurry, thereby regulating the slurry viscosity and achieving dynamic real-time control.

[0027] Secondly, it has strong process adaptability. The raw materials for the additive of this invention are all common chemical raw materials, which are widely available, low in cost, and the process is simple and easy to control, making it suitable for large-scale industrial production. After adding this additive, the problem of abnormal slurry viscosity during the homogenization process of sodium-ion batteries can be effectively solved, improving the stability and uniformity of the slurry.

[0028] Third, it has excellent electrochemical performance. By adding the dynamic viscosity control additive of this invention, the processing quality of subsequent coating, rolling and other processes can be improved, the uniformity of electrode thickness can be improved, and ultimately the performance and production efficiency of sodium-ion batteries can be improved. Attached Figure Description

[0029] Figure 1 Comparison of COV (coating surface density) of sodium-ion battery cathode slurry with and without the additives of this invention;

[0030] Figure 2The graph shows a comparison of the capacity retention rate of a full cell at room temperature during 1C cycling using sodium-ion battery positive electrode slurry with additives from Application Example 1 and without additives from Comparative Example 1. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to application embodiments.

[0032] The present invention relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 40-60 parts of responsive polymer microspheres, 5-15 parts of crosslinking agent, 1-5 parts of initiator, 2-8 parts of dispersing stabilizer, and 20-40 parts of solvent.

[0033] Furthermore, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer.

[0034] Furthermore, the temperature-sensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid.

[0035] Furthermore, the crosslinking agent is N,N-methylenebisacrylamide.

[0036] Furthermore, the initiator is ammonium persulfate.

[0037] Furthermore, the dispersant stabilizer is polyvinyl alcohol.

[0038] Furthermore, the solvent is deionized water.

[0039] Another aspect of the present invention is a method for preparing the above-mentioned dynamic viscosity regulating additive, characterized by comprising the following steps:

[0040] S1. Preparation of core polymer: Add thermosensitive polymer monomer, crosslinking agent and initiator to solvent, and under nitrogen protection, control the reaction temperature at 60-70℃ and react for 3-5 hours to obtain thermosensitive polymer solution.

[0041] S2. Preparation of the outer shell polymer: Add the pH-sensitive polymer monomer, crosslinking agent, and initiator to the solvent. Under nitrogen protection, control the reaction temperature at 50-60℃ and react for 2-4 hours to obtain the pH-sensitive polymer solution.

[0042] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution is slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition is complete, stirring is continued for 1-2 hours to form core-shell structured responsive polymer microspheres.

[0043] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0044] Furthermore, in step S3, the high-speed stirring speed is 800-1200 rpm.

[0045] It should be noted that in the preparation steps S1 and S2 of this invention, there are no special restrictions on the addition ratio of the same components. The ratio can be flexibly adjusted according to the reaction system, so that the components of the additive obtained after mixing in steps S3 and S4 meet the ratio requirements.

[0046] Example 1

[0047] This embodiment relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 60 parts of responsive polymer microspheres, 10 parts of crosslinking agent, 1 part of initiator, 8 parts of dispersing stabilizer, and 30 parts of solvent.

[0048] Specifically, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer. The thermosensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid; the crosslinking agent is N,N-methylenebisacrylamide; the initiator is ammonium persulfate; the dispersing stabilizer is polyvinyl alcohol; and the solvent is deionized water.

[0049] The dynamic viscosity control additive in this embodiment is prepared using the following method:

[0050] S1. Preparation of core polymer: Thermosensitive polymer monomer, crosslinking agent and initiator are added to solvent. Under nitrogen protection, the reaction temperature is controlled at 70℃ and the reaction is carried out for 4 hours to obtain thermosensitive polymer solution.

[0051] S2. Preparation of the outer shell polymer: pH-sensitive polymer monomer, crosslinking agent and initiator are added to the solvent. Under nitrogen protection, the reaction temperature is controlled at 60℃ and the reaction is carried out for 3 hours to obtain pH-sensitive polymer solution.

[0052] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution is slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition is complete, stirring is continued for 2 hours to form core-shell structured responsive polymer microspheres. Specifically, the high-speed stirring speed is 1000 rpm.

[0053] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0054] Example 2

[0055] This embodiment relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 50 parts of responsive polymer microspheres, 5 parts of crosslinking agent, 5 parts of initiator, 5 parts of dispersing stabilizer, and 20 parts of solvent.

[0056] Specifically, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer. The thermosensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid; the crosslinking agent is N,N-methylenebisacrylamide; the initiator is ammonium persulfate; the dispersing stabilizer is polyvinyl alcohol; and the solvent is deionized water.

[0057] The dynamic viscosity control additive in this embodiment is prepared using the following method:

[0058] S1. Preparation of core polymer: Thermosensitive polymer monomer, crosslinking agent and initiator are added to solvent, and under nitrogen protection, the reaction temperature is controlled at 65℃ and the reaction is carried out for 3 hours to obtain thermosensitive polymer solution.

[0059] S2. Preparation of the outer shell polymer: pH-sensitive polymer monomer, crosslinking agent, and initiator are added to a solvent. Under nitrogen protection, the reaction temperature is controlled at 55°C and the reaction is carried out for 2 hours to obtain a pH-sensitive polymer solution.

[0060] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution was slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition was complete, the stirring reaction continued for 1.5 hours to form core-shell structured responsive polymer microspheres. Specifically, the high-speed stirring speed was 800 rpm.

[0061] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0062] Example 3

[0063] This embodiment relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 40 parts of responsive polymer microspheres, 15 parts of crosslinking agent, 3 parts of initiator, 2 parts of dispersing stabilizer, and 40 parts of solvent.

[0064] Specifically, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer. The thermosensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid; the crosslinking agent is N,N-methylenebisacrylamide; the initiator is ammonium persulfate; the dispersing stabilizer is polyvinyl alcohol; and the solvent is deionized water.

[0065] The dynamic viscosity control additive in this embodiment is prepared using the following method:

[0066] S1. Preparation of core polymer: Thermosensitive polymer monomer, crosslinking agent and initiator are added to solvent, and under nitrogen protection, the reaction temperature is controlled at 60℃ and the reaction is carried out for 5 hours to obtain thermosensitive polymer solution.

[0067] S2. Preparation of the outer shell polymer: pH-sensitive polymer monomer, crosslinking agent, and initiator are added to a solvent. Under nitrogen protection, the reaction temperature is controlled at 50°C and the reaction is carried out for 4 hours to obtain a pH-sensitive polymer solution.

[0068] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution is slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition is complete, stirring is continued for 1 hour to form core-shell structured responsive polymer microspheres. Specifically, the high-speed stirring speed is 1200 rpm.

[0069] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0070] Example 4

[0071] This embodiment relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 55 parts of responsive polymer microspheres, 7 parts of crosslinking agent, 4 parts of initiator, 3 parts of dispersing stabilizer, and 35 parts of solvent.

[0072] Specifically, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer. The thermosensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid; the crosslinking agent is N,N-methylenebisacrylamide; the initiator is ammonium persulfate; the dispersing stabilizer is polyvinyl alcohol; and the solvent is deionized water.

[0073] The dynamic viscosity control additive in this embodiment is prepared using the following method:

[0074] S1. Preparation of core polymer: Thermosensitive polymer monomer, crosslinking agent and initiator are added to solvent, and under nitrogen protection, the reaction temperature is controlled at 67℃ and the reaction is carried out for 3.5 hours to obtain thermosensitive polymer solution.

[0075] S2. Preparation of the outer shell polymer: pH-sensitive polymer monomer, crosslinking agent, and initiator are added to a solvent. Under nitrogen protection, the reaction temperature is controlled at 58°C and the reaction is carried out for 2.5 hours to obtain a pH-sensitive polymer solution.

[0076] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution was slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition was complete, the stirring reaction continued for 1.8 hours to form core-shell structured responsive polymer microspheres. Specifically, the high-speed stirring speed was 900 rpm.

[0077] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0078] Example 5

[0079] This embodiment relates to a dynamic viscosity control additive for sodium-ion battery homogenization process, comprising the following components in parts by weight: 45 parts of responsive polymer microspheres, 12 parts of crosslinking agent, 2 parts of initiator, 6 parts of dispersing stabilizer, and 25 parts of solvent.

[0080] Specifically, the responsive polymer microspheres have a core-shell structure, with the core comprising a thermosensitive polymer and the shell comprising a pH-sensitive polymer. The thermosensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid; the crosslinking agent is N,N-methylenebisacrylamide; the initiator is ammonium persulfate; the dispersing stabilizer is polyvinyl alcohol; and the solvent is deionized water.

[0081] The dynamic viscosity control additive in this embodiment is prepared using the following method:

[0082] S1. Preparation of core polymer: Thermosensitive polymer monomer, crosslinking agent and initiator are added to solvent, and under nitrogen protection, the reaction temperature is controlled at 63℃ and the reaction is carried out for 4.5 hours to obtain thermosensitive polymer solution.

[0083] S2. Preparation of the outer shell polymer: pH-sensitive polymer monomer, crosslinking agent, and initiator are added to a solvent. Under nitrogen protection, the reaction temperature is controlled at 53°C and the reaction is carried out for 3.5 hours to obtain a pH-sensitive polymer solution.

[0084] S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution was slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition was complete, the stirring reaction continued for 1.2 hours to form core-shell structured responsive polymer microspheres. Specifically, the high-speed stirring speed was 1100 rpm.

[0085] S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

[0086] In this invention, the functions of the components are described as follows:

[0087] Smart responsive polymer microspheres: with a core-shell structure.

[0088] Core: Composed of the thermosensitive polymer poly-N-isopropylacrylamide (PNIPAM), which has a low critical solution temperature (LCST). When the temperature changes, the molecular chain state changes, resulting in changes in the volume of the microspheres.

[0089] Shell: Composed of pH-sensitive polymer polyacrylic acid (PAA), the molecular chain contains a large number of carboxyl groups. The molecular chain state is different under different acid and alkaline environments, thereby changing the volume of microspheres and their existence state in the slurry.

[0090] Crosslinking agent: N,N-methylenebisacrylamide, used in the polymerization reaction to crosslink the polymer molecular chains, forming a three-dimensional network structure and improving the stability of polymer microspheres.

[0091] Initiator: Ammonium persulfate is selected, which decomposes during the polymerization reaction to generate free radicals, thus initiating monomer polymerization.

[0092] Dispersant stabilizer: Polyvinyl alcohol (PVA) can be adsorbed on the surface of polymer microspheres during their formation, forming a protective film to prevent microsphere aggregation and improve the dispersibility of microspheres in solvents.

[0093] Solvent: Deionized water is used as the medium for the polymerization reaction.

[0094] The mechanism of action of the additives in this invention is as follows:

[0095] Core-shell structure smart response mechanism

[0096] This invention achieves viscosity control of slurry through dynamic changes in the molecular conformation of core-shell structured polymer microspheres. Its core principle is based on the synergistic response of temperature-sensitive and pH-sensitive polymers.

[0097] Thermodynamic response principle of temperature-sensitive core (PNIPAM): Poly(N-isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST, approximately 32°C), and its molecular chain conformation undergoes a reversible transformation with temperature change. When the slurry temperature is below the LCST, the PNIPAM molecular chains are fully bonded to the solvent (water) through hydrogen bonding, exhibiting an extended state. The hydrodynamic volume of the polymer microspheres is relatively large, significantly contributing to the slurry viscosity. When the temperature exceeds the LCST, hydrophobic interactions within the PNIPAM molecular chains dominate, causing the molecular chains to contract rapidly, reducing the microsphere volume, increasing the free volume inside the slurry, and thus lowering the viscosity.

[0098] The charge response principle of pH-sensitive shell (PAA): The carboxyl groups (-COOH) on the polyacrylic acid (PAA) molecular chain exist in ionization equilibrium under different pH environments: Under acidic conditions (pH < pKa, pKa of PAA is about 4.5), the carboxyl groups are ionized (-COOH), the molecular chain curls up due to the weakening of electrostatic repulsion, and the microsphere volume shrinks; Under alkaline conditions (pH > pKa), the carboxyl groups are ionized into carboxylate groups (-COO⁻), the molecular chain stretches due to the enhanced electrostatic repulsion, the microsphere volume expands, and the frictional resistance within the slurry increases, while the viscosity decreases.

[0099] Physicochemical processes of viscosity dynamic regulation

[0100] Temperature-induced viscosity control: During homogenization, the heat generated by stirring or the increase in ambient temperature can cause an abnormal increase in slurry viscosity. At this time, the PNIPAM core shrinks, the microsphere volume decreases, the gap between solid particles in the slurry increases, the fluid shear resistance decreases, and the viscosity decreases accordingly, achieving a negative feedback regulation of "heating-viscosity reduction".

[0101] pH-induced viscosity regulation: When residual alkaline substances in the cathode material (such as polyanionic compounds) cause the pH of the slurry to rise, the molecular chains of the PAA shell expand, the microspheres expand, and the thickening effect on the slurry increases; conversely, if the acidity of the slurry increases due to side reactions, the PAA shrinks, causing the microspheres to shrink and the viscosity to decrease, thus achieving a dynamic response of "pH fluctuation-viscosity balance".

[0102] Synergistic effect of core-shell structure: The temperature-sensitive core and pH-sensitive shell form a stable core-shell interface through a stepwise polymerization process. The response mechanisms of the two are independent yet synergistic: the dual stimulation of temperature and pH can superimpose to regulate the change in microsphere volume, which has a wider range of applications than single-response additives; when the core shrinks / expands, the charge change of the shell can adjust the hydrophilicity and hydrophobicity of the microsphere surface, further optimizing the dispersibility of the slurry and avoiding viscosity abnormalities caused by agglomeration.

[0103] Synergistic effect principle of additive components

[0104] Crosslinking agents (such as N,N-methylenebisacrylamide): connect polymer molecular chains through covalent bonds to form a three-dimensional network structure, preventing the microspheres from dissolving or structurally breaking during the response process and ensuring the stability of repeated responses.

[0105] Dispersing stabilizers (such as PVA): adsorb onto the surface of microspheres to form a hydration film, inhibiting microsphere aggregation through steric hindrance effect, ensuring uniform dispersion in the slurry, thereby achieving consistent viscosity control.

[0106] Initiators (such as ammonium persulfate): decompose to generate free radicals to initiate polymerization reactions, control polymer molecular weight and chain segment distribution, and optimize the response sensitivity and mechanical strength of microspheres.

[0107] The product of this invention has been verified through examples to meet the dynamic control of the viscosity of homogenate for different types of sodium-ion batteries.

[0108] Application Example 1

[0109] This application example relates to a dynamic viscosity control additive for sodium-ion battery homogenization processes, and its preparation method includes the following steps:

[0110] S1. Preparation of core polymer: 20 parts of poly(N-isopropylacrylamide) monomer, 2 parts of crosslinking agent N,N-methylenebisacrylamide, and 0.5 parts of initiator ammonium persulfate were added to 10 parts of deionized water. Under nitrogen protection, the mixture was stirred until homogeneous, and the reaction temperature was controlled at 60°C for 3 hours to obtain a thermosensitive polymer solution.

[0111] S2. Preparation of the outer shell polymer: 20 parts of polyacrylic acid monomer, 3 parts of crosslinking agent N,N-methylenebisacrylamide, and 0.5 parts of initiator ammonium persulfate were added to 10 parts of deionized water. Under nitrogen protection, the mixture was stirred until homogeneous, and the reaction temperature was controlled at 50°C for 2 hours to obtain a pH-sensitive polymer solution.

[0112] S3. Preparation of Smart Response Polymer Microspheres: The temperature-sensitive polymer solution obtained in step 1 is slowly added dropwise to the pH-sensitive polymer solution obtained in step 2, while simultaneously stirring at a high speed of 800 rpm. After the addition is complete, stirring continues for 1 hour to ensure that the core polymer is uniformly dispersed in the outer shell polymer solution and undergoes a cross-linking reaction, forming core-shell structured smart response polymer microspheres.

[0113] S4. Preparation of additive mixture:

[0114] Add 2 parts of polyvinyl alcohol as a dispersant and stabilizer to the solution containing the smart responsive polymer microspheres obtained in step 3, and stir until homogeneous. This allows the dispersant and stabilizer to be adsorbed onto the surface of the polymer microspheres, resulting in a dynamic viscosity regulating additive.

[0115] Performance testing

[0116] When this additive was applied to the homogenization process of sodium-ion battery cathode slurry, the viscosity of the slurry with this additive decreased from 6014 mPa·s to 5172 mPa·s when the slurry temperature increased from 25℃ to 35℃; and the viscosity of the slurry with this additive decreased from 5733 mPa·s to 5231 mPa·s when the pH value of the slurry increased from 7 to 9. The surface density COV of the electrode obtained by subsequent coating was 0.304%, and the capacity retention rate of the full cell after 1000 cycles at 1C at room temperature was 96.63%.

[0117] Comparative Example

[0118] Using the same formulation and stirring process as in Application Example 1, and homogenizing under the same temperature and humidity conditions, the difference was that the additives of this invention were not added. As a result, when the slurry temperature increased from 25°C to 35°C, the slurry viscosity increased from 6133 mPa·s to 8816 mPa·s; when the slurry pH value increased from 7 to 9, the slurry viscosity increased from 6087 mPa·s to 9382 mPa·s; the surface density COV of the electrode obtained by subsequent coating was 0.525%. The same method was used to prepare a full cell for testing, and the capacity retention rate was 94.54% after 1000 cycles at 1C at room temperature.

[0119] Application Example 2

[0120] This application example relates to a dynamic viscosity control additive for sodium-ion battery homogenization processes, and its preparation method includes the following steps:

[0121] S1. Preparation of core polymer: 25 parts of poly(N-isopropylacrylamide) monomer, 3 parts of crosslinking agent N,N-methylenebisacrylamide, and 1 part of initiator ammonium persulfate were added to 15 parts of deionized water. Under nitrogen protection, the mixture was stirred until homogeneous, and the reaction temperature was controlled at 65°C for 4 hours to obtain a thermosensitive polymer solution.

[0122] S2. Preparation of the outer shell polymer: 25 parts of polyacrylic acid monomer, 4 parts of crosslinking agent N,N-methylenebisacrylamide, and 1 part of initiator ammonium persulfate were added to 15 parts of deionized water. Under nitrogen protection, the mixture was stirred until homogeneous, and the reaction temperature was controlled at 55℃ for 3 hours to obtain a pH-sensitive polymer solution.

[0123] S3. Preparation of intelligent responsive polymer microspheres: The temperature-sensitive polymer solution obtained in step 1 is slowly added dropwise to the pH-sensitive polymer solution obtained in step 2, while stirring at high speed (1000 rpm). After the addition is complete, stirring is continued for 1.5 hours to allow the core polymer to be evenly dispersed in the outer shell polymer solution and to undergo a cross-linking reaction, forming core-shell structured intelligent responsive polymer microspheres.

[0124] S4. Preparation of additive mixture: Add 5 parts of dispersant stabilizer polyvinyl alcohol to the solution containing smart responsive polymer microspheres obtained in step 3, stir evenly, so that the dispersant stabilizer is adsorbed on the surface of polymer microspheres to obtain dynamic viscosity control additive.

[0125] Performance testing

[0126] When this additive was applied to the homogenization process of sodium-ion battery negative electrode slurry, experimental results showed that it could effectively control the slurry viscosity even when the slurry temperature and pH value changed. The surface smoothness of the coated electrode was improved, and the initial charge-discharge efficiency of the battery increased by 2.5%.

[0127] Application Example 3

[0128] This application example relates to a dynamic viscosity control additive for sodium-ion battery homogenization processes, and its preparation method includes the following steps:

[0129] S1. Preparation of core polymer: 30 parts of poly(N-isopropylacrylamide) monomer, 4 parts of crosslinking agent (N,N-methylenebisacrylamide), and 2 parts of initiator (ammonium persulfate) were added to 20 parts of deionized water. Under nitrogen protection, the mixture was stirred until homogeneous, and the reaction temperature was controlled at 70°C for 5 hours to obtain a thermosensitive polymer solution.

[0130] S2. Preparation of the outer shell polymer: 30 parts of polyacrylic acid monomer, 5 parts of crosslinking agent N,N-methylenebisacrylamide, and 2 parts of initiator ammonium persulfate were added to 20 parts of deionized water. Under nitrogen protection, the mixture was stirred evenly, and the reaction temperature was controlled at 60℃ for 4 hours to obtain a pH-sensitive polymer solution.

[0131] S3. Preparation of intelligent responsive polymer microspheres: The temperature-sensitive polymer solution obtained in step 1 is slowly added dropwise to the pH-sensitive polymer solution obtained in step 2, while stirring at high speed (1200 rpm). After the addition is complete, stirring is continued for 2 hours to allow the core polymer to be evenly dispersed in the outer shell polymer solution and to undergo a cross-linking reaction, forming core-shell structured intelligent responsive polymer microspheres.

[0132] S4. Preparation of additive mixture: Add 8 parts of dispersant stabilizer polyvinyl alcohol to the solution containing smart responsive polymer microspheres obtained in step 3, stir evenly, so that the dispersant stabilizer is adsorbed on the surface of polymer microspheres to obtain dynamic viscosity control additive.

[0133] Performance testing

[0134] When this additive was applied to the homogenization process of sodium-ion battery slurries with different formulations, it showed good viscosity control effect, effectively improving the quality and stability of the slurry, further verifying the practicality and reliability of the additive of the present invention.

[0135] The same process conditions were used to complete slurry homogenization, coating, and battery assembly. Comparison results of specific application examples are shown in Table 1 and... Figure 1-2 As shown:

[0136] Table 1 Performance Test Results

[0137] Instance number Slurry viscosity (mPa.s) at 25℃ Slurry viscosity (mPa.s) at 35℃ Slurry viscosity (mPa·s) at pH 7 Slurry viscosity (mPa·s) at a pH of 9. Coating surface density COV Battery capacity retention rate after 1000 cycles (%) Application Example 1 (Formula with this additive) 6014 5172 5733 5231 0.304% 96.63% Comparative example (formula without this additive) 6133 8816 6087 9382 0.525% 94.54%

[0138] From Table 1, Figure 1-2 As can be seen, by adding this additive to the sodium-ion battery slurry, the stability of the slurry, the uniformity of the coating density, and the overall performance of the sodium-ion battery are improved.

[0139] The above application embodiments are merely specific application embodiments of the present invention, and their descriptions are relatively specific and detailed, but 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 several modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.

Claims

1. A dynamic viscosity control additive for sodium-ion battery homogenization process, characterized in that it comprises the following components in parts by weight: 40-60 parts of responsive polymer microspheres, 5-15 parts of crosslinking agent, 1-5 parts of initiator, 2-8 parts of dispersing stabilizer, and 20-40 parts of solvent.

2. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 1, characterized in that: The responsive polymer microspheres have a core-shell structure, with the core consisting of a temperature-sensitive polymer and the shell consisting of a pH-sensitive polymer.

3. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 2, characterized in that: The temperature-sensitive polymer is poly(N-isopropylacrylamide); the pH-sensitive polymer is polyacrylic acid.

4. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 1, characterized in that: The crosslinking agent is N,N-methylenebisacrylamide.

5. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 1, characterized in that: The initiator is ammonium persulfate.

6. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 1, characterized in that: The dispersion stabilizer is polyvinyl alcohol.

7. The dynamic viscosity control additive for sodium-ion battery homogenization process according to claim 1, characterized in that: The solvent is deionized water.

8. A method for preparing the dynamic viscosity regulating additive according to any one of claims 1-7, characterized in that... Includes the following steps: S1. Preparation of core polymer: Add thermosensitive polymer monomer, crosslinking agent and initiator to solvent, and under nitrogen protection, control the reaction temperature at 60-70℃ and react for 3-5 hours to obtain thermosensitive polymer solution. S2. Preparation of the outer shell polymer: Add the pH-sensitive polymer monomer, crosslinking agent, and initiator to the solvent. Under nitrogen protection, control the reaction temperature at 50-60℃ and react for 2-4 hours to obtain the pH-sensitive polymer solution. S3. Preparation of responsive polymer microspheres: The temperature-sensitive polymer solution is slowly added dropwise to the pH-sensitive polymer solution while stirring at high speed. After the addition is complete, stirring is continued for 1-2 hours to form core-shell structured responsive polymer microspheres. S4. Preparation of additive mixture: Add a dispersant stabilizer to a solution containing responsive polymer microspheres and stir until homogeneous to obtain a dynamic viscosity regulating additive.

9. The method for preparing the dynamic viscosity regulating additive according to claim 8, characterized in that: In step S3, the high-speed stirring speed is 800-1200 rpm.

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