A composite chemical additive and preparation method thereof

Abstract

The present invention provides a composite chemical additive for use in the preparation of lithium-ion batteries, particularly for preventing sticking and cracking during the electrode sheet rolling process. The composite chemical additive is composed of raw materials, including, by weight, 2-10 parts modified silicone oil, 1-2 parts preservative, 0.5-1 parts pH regulator, 2-4 parts dispersant, and 85-95 parts deionized water. The composite chemical additive forms a protective film during the rolling process, effectively reducing friction and adhesion between the metal roller and the battery electrode sheet material, minimizing electrode sheet damage and wear, while also improving production efficiency and battery performance consistency.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole pieces, and a preparation method thereof. Background Art

[0002] In the manufacturing process of lithium-ion batteries, pole sheet rolling is a critical step that involves evenly coating the active material onto the surface of the current collector. The quality of this step directly affects the performance and life of the battery. However, in traditional rolling processes, problems such as sticking and cracking of the pole sheets are common, which not only compromises the quality of the pole sheets but also reduces production efficiency and overall battery performance. Sticking is mainly caused by high friction between the pole sheet material and the roller surface of the rolling machine, while cracking of the pole sheet is usually caused by stress concentration and poor elastic recovery of the material.

[0003] To address these issues, the industry urgently needs a composite chemical additive that can effectively improve the interaction between the pole piece and the roller surface during the rolling process in the manufacturing process of lithium-ion batteries. Summary of the Invention

[0004] The present application provides a composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole sheets and its preparation method, so as to form a protective film during the rolling process, reduce the friction and adhesion between the metal roller and the battery pole sheet material, and thus reduce the damage and wear of the battery pole sheet.

[0005] The present application provides a composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole pieces. The raw materials for preparation include, by weight, 2-10 parts of modified silicone oil, 1-2 parts of preservative, 0.5-1 part of pH regulator, 2-4 parts of dispersant and 85-95 parts of deionized water.

[0006] Furthermore, the modified silicone oil is terminal hydroxyl polydimethylsiloxane or polysiloxane containing alkyl groups; the preservative is selected from hydroxybenzoic acid esters, phenoxyethanol or a mixture thereof; the pH regulator is ammonia water, monoethanolamine or AMP-95; and the dispersant is at least one of a nonionic surfactant, a polyether or a polyether-modified silicone oil.

[0007] Furthermore, the preservative has a silane functional group, which is used to generate a covalent bond reaction with the battery electrode material on the surface of the battery electrode, thereby providing a long-term protective effect.

[0008] Furthermore, the dispersant is an amphiphilic molecule having directional oleophilic and hydrophilic regions, which is used to effectively reduce the surface tension of the battery electrode material during the rolling process, thereby improving the dispersion performance and preventing reaggregation.

[0009] Furthermore, the weight ratio of the modified silicone oil to the dispersant is 4:1 to 6:1.

[0010] Furthermore, the composite chemical additive also includes a molecular sieve material for absorbing and neutralizing harmful gases that may be released during the rolling process.

[0011] Furthermore, the composite chemical additive also includes 0.05-0.5 parts by weight of an inorganic non-metallic catalyst, wherein the inorganic non-metallic catalyst is selected from a material composed of silicate, zeolite or phosphate, and is used to promote chemical cross-linking reactions on the surface of the battery electrode, enhance the bonding strength between the coating and the electrode, and reduce the risk of material stratification during the rolling process.

[0012] Furthermore, the composite chemical additive also includes 2-3 parts by weight of environmentally sensitive microcapsules, which encapsulate the modified silicone oil and dispersant. The shell material of the environmentally sensitive microcapsules is a biodegradable polymer, which is designed to dissociate when the specific humidity or pH conditions for battery electrode processing are reached, ensuring the timely release of the additive, thereby optimizing the distribution and adhesion effect on the battery electrode surface.

[0013] Furthermore, the composite chemical additive also includes 0.1-1.0 parts by weight of a defoamer, which is selected from silicone or polyether defoamers and is used to effectively inhibit the generation of foam during the rolling process, ensure the uniformity and surface quality of the coating, and at the same time improve the rolling efficiency and reduce material loss during the rolling process.

[0014] The present application provides a method for preparing a composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole pieces, comprising the following steps:

[0015] S1, add 50 parts of deionized water by weight;

[0016] S2. Add 2-10 parts of modified silicone oil and 2-4 parts of dispersant by weight at a stirring speed of 30-50 rpm and stir for 20-30 minutes;

[0017] S3. After the modified silicone oil is fully dissolved, add 35-45 parts of deionized water by weight and 1-2 parts of preservative, and stir for 5-10 minutes;

[0018] S4. Add 0.5-1 part of pH regulator by weight and stir for 5-10 minutes.

[0019] The beneficial technical effects of the present invention are embodied in the following aspects:

[0020] (1) By forming a lubricating film during the rolling process, the additive of the present invention significantly reduces the adhesion between the electrode material and the roller surface, while reducing the stress concentration of the electrode, and effectively preventing the problem of electrode cracking.

[0021] (2) The addition of modified silicone oil improves the affinity between the additive and the electrode material and enhances the wettability, thereby ensuring the uniformity and consistency of the electrode surface coating.

[0022] (3) Since deionized water is mainly used as the solvent and an eco-friendly preservative is used, the additive of the present invention is more environmentally friendly and non-irritating to operators.

[0023] (4) The use of the auxiliary agent of the present invention can reduce the replacement frequency of the scraper blade, reduce the use of consumables, and thus reduce production costs.

[0024] (5) The synergistic effect of the pH regulator and dispersant ensures the uniform distribution of active substances in the coating, avoids electrode defects caused by particle aggregation, and thus improves the overall quality of the battery electrode. DETAILED DESCRIPTION

[0025] The following description sets forth many specific details to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the scope of the present application. Therefore, the present application is not limited to the specific implementations disclosed below.

[0026] The first embodiment of the present application provides a composite chemical additive for preventing sticking and cracking during the rolling process of lithium-ion battery pole pieces. The raw materials for preparation, measured by weight, include 2-10 parts modified silicone oil, 1-2 parts preservative, 0.5-1 part pH adjuster, 2-4 parts dispersant, and 85-95 parts deionized water. The modified silicone oil is a hydroxyl-terminated polydimethylsiloxane or a polysiloxane containing an alkyl group; the preservative is selected from hydroxybenzoates, phenoxyethanol, or mixtures thereof; the pH adjuster is ammonia, monoethanolamine, or AMP-95; and the dispersant is at least one of a nonionic surfactant, a polyether, or a polyether-modified silicone oil.

[0027] The composite chemical additive in this embodiment is designed specifically for the lithium-ion battery pole piece rolling process. It consists of the following ingredients:

[0028] Modified silicone oil: This is the main active ingredient in the additive, forming a protective layer on the surface of the battery electrode to reduce adhesion to the rolling equipment and prevent cracks in the electrode. In this example, the amount of modified silicone oil used is 2-10 parts, depending on the desired viscosity and thickness of the protective film. The modified silicone oils used are hydroxyl-terminated polydimethylsiloxane or polysiloxane containing alkyl groups, chosen for their excellent lubricity and chemical resistance.

[0029] Preservatives: To maintain the stability of the compounded chemical additives and extend their shelf life, 1-2 parts of preservatives are added. Preservatives include parabens, phenoxyethanol, or mixtures thereof. These substances inhibit microbial growth and prevent product deterioration and corruption.

[0030] PH Adjuster: This additive uses 0.5-1 part PH adjuster to maintain the product within the appropriate pH range and ensure optimal performance. Ammonia, monoethanolamine, or AMP-95, as PH adjusters, can adjust the pH of the solution, thereby affecting the solubility and dispersion of the silicone oil in water.

[0031] Dispersant: The addition of dispersant (2-4 parts) is intended to improve the dispersibility of modified silicone oil in deionized water and ensure uniform coating of the additive on the electrode surface. In this embodiment, at least one substance such as non-ionic surfactant, polyether or polyether-modified silicone oil is selected as the dispersant.

[0032] Deionized water: As a solvent and carrier for the additive, deionized water is added in an amount of 85-95 parts. Deionized water is the preferred solvent because it does not contain any mineral salts, thus avoiding ionic contamination that may negatively affect battery performance.

[0033] The modified silicone oil acts as a protective agent in this composite chemical additive, forming a protective film on the surface of the battery electrode. This film effectively reduces direct physical contact between the battery electrode and the rolling machine components, reducing friction and thus minimizing the possibility of wear and tear on the electrode. Furthermore, the protective film prevents the electrode material from sticking during the rolling process.

[0034] Preservatives ensure that composite chemical additives are free from microbial contamination during storage and use, maintaining the long-term stability and reliability of the product. pH regulators maintain the pH of composite chemical additives within the optimal range, improving the stability and dispersibility of modified silicone oils while preventing any instability caused by pH fluctuations.

[0035] The use of dispersants is to ensure the stable dispersion of additives in the water-based environment and ensure uniformity during the coating process. Finally, deionized water is used as a solvent to provide an ion-free pure medium, which helps to maintain the cleanliness and purity of the electrode coating process. It also serves as a dilution and carrying medium for other ingredients.

[0036] In this example, through careful ingredient selection and formulation adjustments, a composite chemical additive was developed that prevents roller sticking and electrode cracking while maintaining long-term stability and reliability. This additive is particularly suitable for use in the electrode roll-pressing process for lithium-ion batteries. The selection and proportioning of each ingredient are designed to maximize the additive's performance during battery manufacturing and ensure its effectiveness in practical applications.

[0037] Table 1 Performance comparison of composite chemical additives prepared in different combinations

[0038]

[0039]

[0040] Table 1 is intended to show the performance comparison of composite chemical additives with different formulations in the rolling process of lithium-ion battery pole pieces. Each formulation is composed of five main ingredients mixed in a specific proportion. Different formulation proportions affect the overall performance of the additive. The formulation numbers A to D in the table represent four different test samples. The dosage of the ingredients in each sample is different, and the purpose is to test the performance differences under various dosages. The performance test results are rated according to pre-set quantitative standards for comparison. It should be pointed out that in this embodiment and the other embodiments below, unless otherwise specified, the modified silicone oil uses terminal hydroxyl polydimethylsiloxane, the preservative uses phenoxyethanol, the pH regulator uses ammonia water, and the dispersant uses a non-ionic surfactant.

[0041] In Table 1, we can see that increasing the modified silicone oil content from 2 to 10 parts per liter generally affects the additive's viscosity and the thickness of the protective film formed. The preservative content is maintained between 1 and 2 parts per liter to ensure that the additive inhibits microbial growth during storage and use. The pH regulator and dispersant content vary between 0.5 and 1 part per liter and 2 and 4 parts per liter, respectively, affecting the additive's pH stability and dispersibility in deionized water. Deionized water serves as the base solvent and carrier, and its content is adjusted accordingly based on the amounts of the other ingredients.

[0042] Performance evaluation is divided into three categories:

[0043] (1) Rolling effect: This test examines the ability of the additive to prevent sticking during the rolling process. Excellent rolling effect means that there is very little sticking of the electrode during the rolling process. Good means that there is some sticking, but it is still within the controllable range. Fair means that sticking is more frequent.

[0044] The following is a quantitative standard for the roller pressing effect level:

[0045] Excellent: In the standard roller pressing test, the pole piece coated with composite chemical additives showed extremely low roller sticking phenomenon, with an incidence rate of less than 5%.

[0046] Good: The occurrence rate of electrode sticking is between 5% and 15%, which means that in most cases the additive can effectively prevent electrode sticking, but it may still occur in some cases.

[0047] Generally: The occurrence rate of electrode sticking is more than 15%, which means that the effect of the additive on preventing the sticking phenomenon is not particularly ideal.

[0048] (2) Pole crack resistance: This test measures the ability of the pole piece to resist crack formation after rolling. Excellent crack resistance indicates that there are almost no cracks in the pole piece, good crack resistance indicates that there are some cracks, but the number is small, and average crack resistance means that there are relatively many cracks.

[0049] The following are the quantitative standards for the pole piece crack resistance performance level:

[0050] Excellent: The pole piece shows extremely high crack resistance after rolling, with a crack incidence rate of less than 1%.

[0051] Good: The crack incidence rate is between 1% and 5%, indicating that the electrode has good resistance to cracking, but cracks may occur under high pressure or adverse conditions.

[0052] General: The crack incidence rate exceeds 5%, indicating that the pole piece is prone to cracking after rolling, and the additive formula or processing conditions need to be improved.

[0053] (3) Long-term stability: This evaluates the stability of the additive after a certain period of storage. Excellent long-term stability means that the additive undergoes almost no changes in chemical and physical properties during storage. Good long-term stability means that the changes are within an acceptable range, while fair long-term stability means that the additive's properties change significantly.

[0054] The following are quantitative criteria for the long-term stability performance level:

[0055] Excellent: After at least 6 months of storage, the chemical and physical properties of the composite chemical additive have not changed significantly, indicating that the additive has excellent stability.

[0056] Good: After 6 months of storage, the chemical and physical properties of the additive show no more than 5% change, indicating that the additive has good stability, but may show slight changes under extreme conditions.

[0057] General: After 6 months of storage, the chemical and physical properties of the additive show changes of more than 5%, which may affect its performance and safety and require improvement of the formulation or storage conditions.

[0058] In Table 1, the specific dosages and test results of formulas A to D are as follows:

[0059] Formulation A uses the lowest amount of ingredients and therefore may have a thinner protective film and lower viscosity, which may result in rolling effect and pole piece crack resistance only reaching "good" and "fair" levels, but long-term stability is shown as "excellent".

[0060] The moderate dosage of ingredients in Formulations B and C may have achieved a good balance, improving the rolling effect and pole piece crack resistance to "excellent" and "good" levels, while maintaining "excellent" long-term stability.

[0061] Formulation D, which uses the higher end of the ingredient dosage range, may result in somewhat reduced rolling performance and long-term stability (rated as "good" and "fair"), likely due to the reduced performance resulting from the excessively high ingredient dosage.

[0062] These performance evaluation results provide implementers with important information about the effects of different formulations on the performance of composite chemical additives and can guide further formulation optimization.

[0063] In the second embodiment of the present application, based on the first embodiment, the preservative has a silane functional group, which is used to react with the battery electrode material on the surface of the battery electrode to produce a covalent bond, thereby providing a long-term protective effect.

[0064] The role of silane functional groups in chemical additives is to form a strong protective film by forming a covalent bond with the surface of the battery electrode material. This reaction is usually achieved through one or more silane coupling agents, which react with the active material of the battery electrode (such as graphite or lithium metal oxide) and the surface of the current collector. This chemical bond is highly bonded and not easily stripped by water or other solvents, providing long-term protection for the battery electrode, preventing the intrusion of moisture, oxygen, and other substances that may cause performance degradation.

[0065] In addition, the addition of silane functional groups not only improves the anti-corrosion ability of the additive, but also has the potential to improve the overall chemical stability of the battery electrode, because this covalent bond protective film can resist the erosion of the electrode material by environmental factors, such as the stability of electrochemical reactions during battery charging and discharging.

[0066] Performance test design:

[0067] In order to prove that the preservative with added silane functional groups can effectively provide long-term protection, the following performance tests can be designed:

[0068] Purpose of the test:

[0069] Verify the ability and durability of preservatives containing silane functional groups to form a protective film on the surface of battery electrodes.

[0070] Test Materials:

[0071] Battery pole material (such as graphite or lithium iron phosphide)

[0072] Anticorrosive composite chemical additives containing silane functional groups

[0073] A standard preservative without silane functional groups was used as a control

[0074] Test method:

[0075] (1) Surface treatment:

[0076] The battery electrodes were divided into two groups: the experimental group was coated with a preservative containing silane functional groups, and the control group was coated with a standard preservative without silane functional groups.

[0077] The anticorrosive agent is applied to the surface of the electrode by spin coating or dipping and allowed to dry at room temperature to form a protective film.

[0078] (2) Accelerated aging test:

[0079] Place the treated electrode in an accelerated aging chamber, set appropriate temperature and humidity conditions (such as 60°C, 90% relative humidity), and continue for a certain period (such as 500 hours).

[0080] Performance evaluation:

[0081] The anti-corrosion effect of the electrode can be evaluated before and after the aging test, and the changes in its electrochemical properties can be evaluated through electrochemical tests (such as cyclic voltammetry and battery charge and discharge tests).

[0082] Surface analysis techniques such as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) are used to observe the chemical changes on the electrode surface and the integrity of the protective film.

[0083] Results comparison:

[0084] The results of the experimental group and the control group were compared to evaluate the effect of the preservative containing silane functional groups in improving the corrosion resistance and electrochemical stability of battery electrodes.

[0085] The protective effect of silane functional group preservatives is determined based on the electrochemical properties and the stability of the surface protective film.

[0086] Table 2 Performance comparison test results of silane functional group preservatives

[0087]

[0088] Table 2 shows that the pre-aging data for the experimental and control groups show consistent battery capacity and internal resistance, representing baseline data. Data after accelerated aging indicate that the experimental group's capacity retention and internal resistance increase rate are superior to those of the control group, demonstrating that the silane-functional preservative more effectively protects the battery electrodes.

[0089] The capacity retention rate is the ratio of the battery capacity before and after aging. The experimental group had a higher capacity retention rate, indicating excellent aging resistance. The internal resistance increase rate is the ratio of the battery internal resistance before and after aging. The experimental group had a smaller increase in internal resistance, indicating that the conductivity of the battery electrode was less affected by aging.

[0090] SEM analysis results showed that the surface protective film of the experimental group had no obvious cracks or peeling after aging, while these phenomena occurred in the control group, indicating that the preservative containing silane functional groups performed better in maintaining the integrity of the surface protective film.

[0091] XPS analysis results showed that there was no obvious change in chemical composition of the experimental group after aging, while oxides and other corrosion products were detected in the control group, which indicates that preservatives containing silane functional groups are better able to maintain the chemical stability of the electrode surface.

[0092] Based on the above data, it can be concluded that preservatives containing silane functional groups have a better protective effect than traditional preservatives in improving the corrosion resistance and electrochemical stability of battery electrodes.

[0093] In the third embodiment of the present application, based on the first embodiment, the dispersant is an amphiphilic molecule having directional lipophilic and hydrophilic regions, which is used to effectively reduce the surface tension of the battery electrode material during the rolling process, thereby improving the dispersion performance and preventing reaggregation.

[0094] The structure of amphiphilic molecules usually consists of a long hydrophobic carbon chain (lipophilic part) and a polar hydrophilic head group, such as carboxylate, sulfonate or polyol. This structure enables the dispersant to self-assemble into microcapsules or micelles in aqueous media, encapsulating the particles of the electrode material, thereby reducing their surface tension, increasing the repulsion between particles, and preventing them from reuniting during the rolling process.

[0095] In lithium-ion battery production, roller pressing is the process of uniformly applying a mixture of active materials and binders onto a metal foil. Dispersants ensure that these components form a uniform slurry, resulting in a battery electrode with consistent performance. Particle aggregation can lead to uneven battery performance, impacting battery life and reliability.

[0096] Performance test design:

[0097] To demonstrate the effectiveness of an amphiphilic dispersant containing oriented lipophilic and hydrophilic regions, the following performance test was designed:

[0098] Purpose of the test:

[0099] Evaluate the effectiveness of amphiphilic dispersants in reducing the surface tension of battery electrode materials, improving dispersion properties and preventing reaggregation.

[0100] Test Materials:

[0101] Battery pole coating using standard dispersant (control group)

[0102] Battery electrode coating using amphiphilic molecular dispersant (experimental group)

[0103] The test method is as follows:

[0104] (1) Surface tension test:

[0105] Use a tensiometer to measure the surface tension of the coating.

[0106] The measurement results of the experimental group and the control group were compared to determine the effect of the amphiphilic dispersant on the surface tension.

[0107] (2) Dispersion performance test:

[0108] Observe and record the particle size and distribution of the coating mixture after a certain period of time.

[0109] Use an optical microscope or a particle size analyzer to evaluate whether the particles are evenly dispersed.

[0110] (3) Reunion phenomenon test:

[0111] After a period of rest, evaluate whether the particles have reaggregated.

[0112] The particles with reaggregation were analyzed by SEM (scanning electron microscopy).

[0113] (4) Rolling process evaluation:

[0114] The coating is actually applied to the battery pole piece and the rolling process is carried out.

[0115] Evaluate the surface flatness and uniformity of the pole piece after rolling.

[0116] (5) Battery performance test:

[0117] The battery was made and subjected to charge and discharge cycle testing.

[0118] The battery capacity, internal resistance and cycle stability were recorded to evaluate the effect of electrode quality on battery performance.

[0119] Result analysis:

[0120] All test results were analyzed comprehensively to compare the performance of the experimental and control groups.

[0121] Verify the effect of amphiphilic dispersants in improving the dispersion performance of coatings, reducing reaggregation and optimizing the roller pressing process.

[0122] Evaluate the quality of the final battery electrode based on the battery charge and discharge performance test results.

[0123] Table 3. Performance comparison of amphiphilic dispersants

[0124]

[0125]

[0126] As shown in Table 3, the surface tension of the experimental group is significantly lower than that of the control group, indicating that the amphiphilic dispersant is more effective in reducing the surface tension of the coating.

[0127] Average particle size: The particle size of the experimental group was smaller and more evenly distributed, indicating better dispersion effect.

[0128] Particle size distribution uniformity: The experimental group had a more consistent particle size distribution with a lower standard deviation.

[0129] Reaggregation phenomenon score: The experimental group scored lower, indicating that the amphiphilic dispersant was more effective in preventing particle reaggregation.

[0130] Surface flatness score after rolling: The experimental group obtained a higher score, reflecting that the surface of the electrode is smoother after rolling.

[0131] Initial battery capacity: Both groups start out the same to ensure accuracy of comparison.

[0132] Capacity retention rate: After the cycle test, the capacity retention rate of the experimental group was higher than that of the control group, indicating that the battery electrode quality was better.

[0133] Internal resistance change rate: The internal resistance of the experimental group increased less, indicating that the electrochemical performance of the battery is more stable.

[0134] Charge and discharge cycle stability score: The experimental group has a higher score, indicating that the battery performance changes little after multiple charge and discharge cycles.

[0135] Based on the above data, it can be concluded that the composite chemical additive containing an amphiphilic dispersant has significant advantages in improving the dispersion performance of battery electrode coatings, reducing agglomeration, and optimizing the electrode surface quality during the roller pressing process. In addition, battery performance test results show that battery electrodes using this dispersant can maintain higher capacity and more stable electrochemical performance during long-term use.

[0136] In the fourth embodiment of the present application, based on the first embodiment, the weight ratio of the modified silicone oil to the dispersant is 4:1 to 6:1.

[0137] This specific ratio is based on experimental results and theoretical calculations, aiming to achieve optimal lubrication and dispersion effects while ensuring the uniformity of the coating and the stability of the pole piece material.

[0138] In composite chemical additives, modified silicone oil is usually used to provide lubricity and reduce friction and adhesion of the pole piece, while dispersant is used to promote the uniform dispersion of powders (such as active substances and conductive additives) in the solvent. The weight ratio of modified silicone oil to dispersant has an important influence on the final performance of the additive. A higher silicone oil ratio is beneficial to lubricity, but if excessive, it may affect the conductivity and bonding strength of the coating. On the contrary, too high a proportion of dispersant may lead to unnecessary cost increases, and excessive dispersion may affect the structural stability of the coating. Therefore, it is crucial to determine the optimal weight ratio.

[0139] Performance test design:

[0140] The purpose of the performance test is to verify that by optimizing the ratio of modified silicone oil to dispersant, the performance of composite chemical additives in battery electrode production can be improved. The following is the design of the performance test:

[0141] Purpose of the test:

[0142] Ensure that the composite chemical additive provides excellent coating uniformity, lubricity and battery performance at a given modified silicone oil to dispersant ratio.

[0143] Test Materials:

[0144] Experimental group: a composite chemical additive consisting of modified silicone oil and dispersant mixed in a ratio of 4:1 to 6:1

[0145] Control group: using composite chemical additives with non-optimized ratios

[0146] Test method:

[0147] (1) Coating uniformity test:

[0148] Use a precise balance to weigh the additive ingredients and mix them to a ratio of 4:1 to 6:1.

[0149] The additive is applied to the battery electrode and after drying, the coating uniformity is evaluated using a microscope.

[0150] (2) Lubricity test:

[0151] The friction coefficient of the electrode surface after coating with the additive was measured using a friction coefficient tester.

[0152] Compare the differences in friction coefficient between the experimental group and the control group.

[0153] (3) Battery performance test:

[0154] Prepare battery samples and conduct charge and discharge cycle tests.

[0155] Measure and record initial capacity, capacity retention, and internal resistance.

[0156] Table 4. Comparison of performance of composite chemical additives composed of modified silicone oil and dispersant in different proportions

[0157]

[0158]

[0159] As can be seen from Table 4, the experimental groups with a ratio of 4:1 and 5:1 showed excellent coating uniformity, with the 5:1 ratio slightly better than 4:1. Although the 6:1 ratio also showed good uniformity, it was lower than the other two ratios.

[0160] The 5:1 ratio achieved the lowest surface friction coefficient, indicating that this ratio may provide the best lubrication without sacrificing the structural integrity of the coating.

[0161] All groups, including the control group, had the same initial volume to ensure consistency of comparison.

[0162] Capacity retention after 100 cycles: The 5:1 ratio showed the highest capacity retention, suggesting that this ratio may provide the best balance between lubrication effect and coating integrity, which is beneficial for long-term battery performance.

[0163] Internal resistance increase rate: The internal resistance increase rate of the 5:1 ratio is the lowest, which suggests that the battery maintains better electrochemical stability during the cycle and has advantages over other ratios and the control group.

[0164] Based on Table 4, it can be concluded that although the experimental groups within all tested ratio ranges showed improved performance compared to the non-optimized ratio control group, the 5:1 modified silicone oil to dispersant ratio provided the best overall performance.

[0165] In the fifth embodiment of the present application, based on the first embodiment, the composite chemical additive further includes a molecular sieve material for absorbing and neutralizing harmful gases that may be released during the rolling process.

[0166] Molecular sieves are porous materials that selectively adsorb molecules of specific sizes through their pore structure and are commonly used in adsorption and separation applications. During the battery electrode rolling process, the use of molecular sieves can effectively absorb potentially released harmful gases, such as volatile organic compounds (VOCs) or other decomposition products, thereby improving work environment safety and consistent battery performance.

[0167] The addition of molecular sieve materials can achieve the following functions:

[0168] Absorb harmful gases: During the roller pressing process, due to the mechanical pressure and heat, some chemicals may decompose and release harmful gases. Molecular sieves can capture these gases and prevent them from spreading into the environment.

[0169] Neutralization: Some molecular sieve materials can also neutralize these harmful substances at the chemical level, such as through acid-base neutralization reaction, or catalytic decomposition into harmless substances.

[0170] Improved electrode quality: By reducing contamination in the production environment, molecular sieves help maintain the quality of electrode materials and final battery products.

[0171] Molecular sieve types include, but are not limited to, 3A, 4A, 5A, and 13X. The choice depends on the size and chemical properties of the target gas. In practice, the amount of molecular sieve added and its form (e.g., powder, granules, or coating) should be determined based on the specific application and the desired adsorption capacity.

[0172] Performance test design:

[0173] To prove that the addition of molecular sieve materials can effectively absorb and neutralize harmful gases, improve the safety of the production process, and maintain the quality of the electrode, the following is a performance test design:

[0174] Purpose of the test:

[0175] Verify the ability of composite chemical additives added with molecular sieve materials to absorb harmful gases during rolling and its impact on battery performance.

[0176] Test Materials:

[0177] Experimental group: composite chemical additives with molecular sieve materials added.

[0178] Control group: composite chemical additive without adding molecular sieve material.

[0179] Test method:

[0180] (1) Harmful gas absorption test:

[0181] The roller pressing process was simulated in a closed container and the changes in the concentration of harmful gases were monitored.

[0182] The gas concentration in the container was measured using a gas analyzer and compared between the experimental and control groups.

[0183] (2) Neutralization effect test:

[0184] If the molecular sieve has chemical neutralization ability, the neutralization effect can be evaluated by detecting the product.

[0185] Analyze changes in the chemical composition of the gas in the container to confirm the neutralization of harmful substances.

[0186] (3) Electrode quality assessment:

[0187] Prepare rolled battery electrodes and perform visual and physical inspections.

[0188] Evaluate the surface quality, thickness consistency and mechanical strength of the pole pieces.

[0189] (4) Battery performance test:

[0190] Make battery cells and conduct standard charge and discharge tests.

[0191] Compare the capacity, internal resistance and cycle stability of batteries.

[0192] Table 5. Comparison of performance of composite chemical additives with molecular sieves

[0193]

[0194]

[0195] As can be seen from Table 5, with regard to the harmful gas absorption efficiency, the experimental group showed the ability to almost completely absorb the harmful gases in the container, while the control group had no such effect.

[0196] Harmful gas neutralization efficiency: The experimental group was also able to significantly neutralize these gases and reduce the presence of harmful substances.

[0197] Pole surface quality score: The experimental group has a higher pole surface quality score, indicating that there are fewer defects in the rolling process.

[0198] Pole thickness consistency score: The experimental group has more consistent pole thickness, which may be attributed to better production conditions.

[0199] Battery capacity retention rate: The capacity retention rate of the experimental group after charge and discharge cycles was higher than that of the control group, indicating that the addition of molecular sieve additives can improve the stability of battery performance.

[0200] Battery internal resistance change rate: The internal resistance change of the experimental group is lower, indicating that the battery maintains better performance during use.

[0201] From these data, it can be clearly seen that the addition of composite chemical additives with molecular sieve materials has a positive effect in improving the working environment, absorbing and neutralizing harmful gases, and improving the performance of the final battery product.

[0202] The sixth embodiment of the present application is based on the first embodiment, and the composite chemical additive also includes 0.05-0.5 parts by weight of an inorganic non-metallic catalyst, and the inorganic non-metallic catalyst is selected from a material composed of silicate, zeolite or phosphate, which is used to promote chemical cross-linking reactions on the surface of the battery electrode, enhance the bonding strength between the coating and the electrode, and reduce the risk of material stratification during the rolling process.

[0203] In this embodiment, the inorganic non-metallic catalyst promotes a chemical cross-linking reaction during the coating process of the battery electrode. This chemical cross-linking reaction improves the structural stability of the coating, increases the bonding strength between the coating and the electrode, and reduces delamination or shedding of the coating during rolling, which is crucial for improving battery performance and reliability.

[0204] The inorganic non-metallic catalysts are selected based on their ability to activate or accelerate the crosslinking reaction at room temperature or at relatively low heat treatment temperatures. Silicates, zeolites, and phosphates are all widely used in catalysis, and are used as catalysts due to their porous structures and surface active sites. In this application, they can promote crosslinking between the polymer chains that make up the coating, forming a denser network with superior mechanical properties.

[0205] During the preparation process, the amount of catalyst added should be strictly controlled at 0.05-0.5 parts by weight to ensure sufficient catalytic effect without excessively affecting the functions of other components. This ratio is obtained through experimental optimization and aims to balance catalytic efficiency and cost-effectiveness.

[0206] Performance test design:

[0207] To demonstrate the effectiveness of a composite chemical additive containing an inorganic non-metallic catalyst in improving coating bonding strength and reducing the risk of delamination, a performance test was designed as follows:

[0208] Purpose of the test:

[0209] Verify the effectiveness of inorganic non-metallic catalysts in promoting the cross-linking reaction of battery electrode coatings and improving the structural stability of the coatings.

[0210] Test Materials:

[0211] Experimental group: composite chemical additives with inorganic non-metallic catalysts added.

[0212] Control group: composite chemical additive without adding inorganic non-metallic catalyst.

[0213] Test method:

[0214] (1) Coating bonding strength test:

[0215] Preparation of battery electrodes with various additives.

[0216] The bonding strength between the coating and the electrode is evaluated by peel test or shear strength test.

[0217] (2) Evaluation of chemical cross-linking degree:

[0218] The completion of the cross-linking reaction was assessed by infrared spectroscopy or thermogravimetric analysis.

[0219] Compare the cross-linking degrees between the experimental group and the control group.

[0220] (3) Rolling process stability test:

[0221] After the simulated rolling process, the coating was checked for integrity and any delamination.

[0222] The stability of the coatings was evaluated by visual inspection and physical testing.

[0223] (4) Battery performance test:

[0224] Make batteries and conduct charge and discharge tests.

[0225] Measure battery capacity, internal resistance, and cycle stability.

[0226] Table 6. Comparison of performance of composite chemical additives with added catalysts

[0227]

[0228] As can be seen from Table 6, for the bonding strength: the bonding strength of the experimental group is significantly higher than that of the control group, indicating that the catalyst effectively promotes the cross-linking reaction and enhances the adhesion between the coating and the electrode.

[0229] Cross-linking degree: The cross-linking degree of the experimental group was higher than that of the control group, indicating that the cross-linking reaction of the coating was more complete.

[0230] Coating integrity score: The experimental group scored high, reflecting better coating integrity after roller pressing, with no obvious defects.

[0231] Delamination incidence: The delamination incidence of the experimental group was lower, indicating that the coating was more stable during the rolling process and less likely to delaminate.

[0232] Initial battery capacity: The initial capacity of the two groups is the same to ensure the fairness of the test.

[0233] Capacity retention after cycling: The experimental group showed higher capacity retention after battery charge and discharge cycles, indicating that the catalyst helps maintain battery performance.

[0234] Internal resistance change rate: The internal resistance of the experimental group changed less, indicating that the internal structure of the battery is more stable.

[0235] From these data, it can be concluded that the addition of composite chemical additives with inorganic non-metallic catalysts has a significant effect in improving the bonding strength and structural stability of battery electrode coatings, and helps to improve the performance of the final battery products.

[0236] The seventh embodiment of the present application is based on the first embodiment, and the composite chemical additive also includes 2-3 parts by weight of environmentally sensitive microcapsules, which contain a mixture of modified silicone oil and a dispersant. The shell material of the microcapsules is a biodegradable polymer, which is designed to dissociate when the specific humidity or pH conditions for battery electrode processing are reached, ensuring the timely release of the additive, thereby optimizing the distribution and adhesion effect on the surface of the battery electrode.

[0237] This embodiment provides a composite chemical adjuvant containing environmentally sensitive microcapsules. These microcapsules contain a mixture of modified silicone oil and a dispersant, while the outer shell is made of a biodegradable polymer. This design enables the microcapsules to respond to specific environmental conditions (such as changes in humidity or pH) and release the active ingredients within at the appropriate time during the battery electrode processing. This controlled release mechanism can improve the uniformity and adhesion of the coating while reducing waste and environmental impact.

[0238] The core design of environmentally sensitive microcapsules lies in their ability to respond to environmental changes that may occur during the electrode processing process. For example, during the coating process, if the ambient humidity increases or the pH value changes, these microcapsules will dissociate, releasing the modified silicone oil and dispersant contained within, thereby forming a more uniform coating on the electrode surface. The selection of biodegradable polymers includes PLA (polylactic acid) and PHB (polyhydroxybutyric acid). These materials can be degraded after meeting specific conditions, reducing the problem of long-term environmental accumulation.

[0239] In practice, microcapsule preparation involves selecting an appropriate biodegradable polymer material, encapsulating a modified silicone oil and dispersant mixture within the microcapsules, and adjusting the preparation process to ensure the microcapsules are sensitive to specific humidity or pH levels. The microcapsule size, shell thickness, and content (2-3 parts by weight) require experimental optimization to achieve optimal release.

[0240] Performance test design:

[0241] The purpose of the performance test is to verify whether the controlled release mechanism of the environmentally sensitive microcapsules can improve the coating effect during the electrode processing.

[0242] Test Materials:

[0243] Experimental group: composite chemical additives with environmentally sensitive microcapsules added.

[0244] Control group: composite chemical additives without microcapsules added.

[0245] Test method:

[0246] (1) Controlled release effect test:

[0247] Simulate the battery electrode processing environment and artificially adjust the humidity and pH value.

[0248] The dissociation behavior of the microcapsules and the release of active ingredients under different environmental conditions were observed and recorded.

[0249] (2) Coating uniformity evaluation:

[0250] The two additives are coated on the electrode and dried under specific humidity or pH conditions.

[0251] Assess the uniformity of the coating using optical microscopy or other surface analysis techniques.

[0252] (3) Coating adhesion test:

[0253] The peel test is used to evaluate the adhesion strength between the coating and the electrode.

[0254] The coating adhesion strength of the experimental group and the control group was compared.

[0255] (4) Environmental Impact Assessment:

[0256] The degradation of microcapsule materials was evaluated by biodegradation tests.

[0257] Degradation products are measured and their potential impact on the environment is assessed.

[0258] Table 7. Comparison of performance of composite chemical additives with microcapsules

[0259]

[0260] As can be seen from Table 7, the microcapsules in the experimental group dissociated within 10 minutes and released the active ingredients, while the control group did not have microcapsules, so this test was not applicable.

[0261] Coating uniformity score: The coating uniformity score of the experimental group was higher, indicating that the controlled release of microcapsules helped to form a more uniform coating.

[0262] Coating adhesion strength: The coating adhesion strength of the experimental group was higher than that of the control group, indicating that the active ingredients released from the microcapsules can effectively enhance the bonding between the coating and the electrode.

[0263] Biodegradation rate: The microcapsule material in the experimental group has a high biodegradation rate, reducing the long-term impact on the environment.

[0264] From the above test results, it can be concluded that the composite chemical additives with environmentally sensitive microcapsules can effectively control the release of active ingredients under specific environmental conditions, improve the uniformity and adhesion of the coating, and provide a degradable and environmentally friendly solution.

[0265] The eighth embodiment of the present application is based on the first embodiment, and the composite chemical additive also includes 0.1-1.0 parts by weight of a defoaming agent, and the defoaming agent is selected from silicone or polyether defoaming agents, which is used to effectively inhibit the generation of foam during the rolling process, ensure the uniformity and surface quality of the coating, and at the same time improve the rolling efficiency and reduce material loss during the rolling process.

[0266] During the roller-pressing process, air bubbles in the coating can lead to uneven coating, affecting the quality of the electrode and battery performance. Silicone or polyether defoamers can effectively destabilize the foam and accelerate its dissipation. Silicone defoamers generally have excellent thermal stability and chemical inertness, while polyether defoamers are known for their low surface tension and good dispersibility.

[0267] When preparing composite chemical additives, the amount of defoamer added needs to be precisely controlled within the range of 0.1-1.0 parts by weight to ensure effective defoaming while avoiding affecting other coating properties. Furthermore, selecting the appropriate type of defoamer to ensure compatibility with the other ingredients in the additive is crucial.

[0268] In order to verify the effect of adding a composite chemical additive with a defoaming agent on improving coating uniformity and rolling efficiency, this example adopts the following performance test scheme:

[0269] Purpose of the test:

[0270] Verify the effect of composite chemical additives with added defoamers in suppressing foam generation during roller pressing and its influence on coating quality and roller pressing efficiency.

[0271] Test Materials:

[0272] Experimental group: composite chemical additives with defoaming agent (silicone type) added.

[0273] Control group: composite chemical additives without adding defoaming agent.

[0274] Test methods include:

[0275] (1) Foam generation test:

[0276] Under simulated roller pressing conditions, the foam generation in the coatings of the experimental group and the control group was compared.

[0277] The degree of foam generation was assessed by visual inspection and foam volume measurement.

[0278] (2) Coating uniformity evaluation:

[0279] The electrodes were coated with both additives and the coating uniformity was evaluated using an optical microscope after drying.

[0280] Coating quality is evaluated by coating thickness consistency and surface finish.

[0281] (3) Rolling efficiency test:

[0282] Measure the time and energy consumption during the rolling process.

[0283] Compare the roller pressing efficiency between the experimental group and the control group.

[0284] Table 8. Comparison of performance of composite chemical additives with defoaming agent

[0285]

[0286] Explanation of the data in Table 8:

[0287] Foam amount: The foam generated in the experimental group was significantly less than that in the control group, indicating that the defoamer effectively reduced the generation of foam.

[0288] Coating uniformity score: The coating uniformity score of the experimental group was higher, indicating that the addition of defoamer improved the uniformity and surface quality of the coating.

[0289] Rolling time: The time required for the rolling process of the experimental group was shorter than that of the control group, indicating that the addition of defoaming agent can improve the rolling efficiency.

[0290] Rolling energy consumption: The energy consumption of the rolling process in the experimental group was lower than that in the control group, which further confirmed the improvement of its rolling efficiency.

[0291] Based on the above test results, it can be concluded that the composite chemical additives with the addition of defoaming agent effectively inhibited foam generation during the rolling process, improved the uniformity of the coating and the rolling efficiency, and reduced material loss and energy consumption during the rolling process.

[0292] A ninth embodiment of the present application provides a method for preparing a composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole pieces, comprising the following steps:

[0293] S1, add 50 parts of deionized water by weight;

[0294] S2. Add 2-10 parts of modified silicone oil and 2-4 parts of dispersant by weight at a stirring speed of 30-50 rpm and stir for 20-30 minutes;

[0295] S3. After the modified silicone oil is fully dissolved, add 35-45 parts of deionized water by weight and 1-2 parts of preservative, and stir for 5-10 minutes;

[0296] S4. Add 0.5-1 part of pH regulator by weight and stir for 5-10 minutes. After stirring, turn off the mixer and fill according to the packaging specifications.

[0297] Although the present application is disclosed as above with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

Claims

1. A composite chemical additive for preventing roller sticking and cracking during the rolling process of lithium-ion battery pole pieces, characterized in that: The raw materials for preparation include, by weight, 5-7 parts of modified silicone oil, 1.5-2 parts of preservative, 0.75-1 part of pH regulator, 3-4 parts of dispersant and 86-90 parts of deionized water; the composite chemical additive is coated on the surface of the battery electrode to form a protective film; Among them, the modified silicone oil is terminal hydroxyl polydimethylsiloxane; the pH regulator is ammonia water, monoethanolamine or AMP-95; the dispersant is a non-ionic surfactant; the preservative has a silane functional group; the composite chemical additive also includes a molecular sieve material for absorbing and neutralizing harmful gases released during the rolling process; the composite chemical additive also includes 0.05-0.5 parts by weight of an inorganic non-metallic catalyst, and the inorganic non-metallic catalyst is selected from a material composed of silicate, zeolite or phosphate; the composite chemical additive also includes 2-3 parts by weight of environmentally sensitive microcapsules, the modified silicone oil and dispersant are encapsulated in the environmentally sensitive microcapsules, the shell material of the environmentally sensitive microcapsules is a biodegradable polymer, and the environmentally sensitive microcapsules dissociate when the specific humidity or pH conditions for battery electrode processing are reached; the composite chemical additive also includes 0.1-1.0 parts by weight of a defoamer, and the defoamer is selected from a silicone defoamer.

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