Electrolyte-based defoaming battery slurry, preparation method and application thereof

Abstract

This invention discloses an electrolyte-based defoaming battery slurry, its preparation method, and its application, belonging to the field of lithium-ion battery manufacturing technology. It includes the following raw materials: negative electrode active material, conductive agent, thickener, binder, solvent, and defoamer, wherein the defoamer is one or more of tributyl phosphate, triethyl phosphate, and diethyl carbonate. This invention utilizes the aforementioned electrolyte-based defoaming battery slurry, its preparation method, and its application. By adding a specific type of defoamer in the later stages of battery slurry preparation, bubbles in the slurry can be efficiently eliminated, resulting in a bubble-free coating appearance and significantly improving the coating quality and consistency of the negative electrode sheet. Simultaneously, the selected defoamer is a commonly used component in electrolytes, exhibiting good compatibility with the battery system and not causing side effects on electrochemical performance. Instead, it helps improve the initial coulombic efficiency and long-term cycle stability of lithium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, and in particular to electrolyte-based defoaming battery slurry, its preparation method, and its application. Background Technology

[0002] During the preparation of lithium-ion battery negative electrode slurry, due to the presence of polymeric compounds such as thickeners (e.g., CMC), air is easily entrained and forms tiny bubbles during stirring and dispersion. If these bubbles are not effectively eliminated, they can lead to pinholes and pitted surfaces after coating, severely affecting battery safety and cycle life.

[0003] Currently, most defoamers commonly used in the industry are silicone or alcohol-based surfactants. However, these defoamers are not electrolyte components and may decompose during battery charging and discharging, generating gas or byproducts, leading to battery bulging. Furthermore, existing defoamers often have poor compatibility with aqueous slurry systems, easily precipitating and floating on the slurry surface, thus affecting the consistency of coating surface density.

[0004] Therefore, there is an urgent need to develop a defoaming technology that is both highly efficient at defoaming and perfectly compatible with the battery system, without producing side effects. Summary of the Invention

[0005] The purpose of this invention is to provide an electrolyte-based defoaming battery slurry, its preparation method, and its application. By adding a specific type of defoamer in the later stage of battery slurry preparation, bubbles in the slurry can be efficiently eliminated, resulting in a bubble-free coating appearance and significantly improving the coating quality and consistency of the negative electrode sheet. Simultaneously, the selected defoamer is a commonly used component in electrolytes, exhibiting good compatibility with the battery system and not causing side effects on electrochemical performance. Instead, it helps improve the initial coulombic efficiency and long-term cycle stability of lithium-ion batteries. Furthermore, this defoaming method is simple to operate, easy to industrialize, and avoids the performance degradation problems that may arise from traditional defoamers, achieving synergistic optimization of defoaming effect and battery performance.

[0006] To achieve the above objectives, the present invention provides an electrolyte-based defoaming battery slurry, comprising, by weight, the following raw materials: 80-98 parts of negative electrode active material, 0.5-5 parts of conductive agent, 0.5-3 parts of thickener, 0.5-5 parts of binder, 40-120 parts of solvent, and 0.01-1 parts of defoamer, wherein the defoamer is one or more of tributyl phosphate, triethyl phosphate, and diethyl carbonate.

[0007] Preferably, the defoamer accounts for 0.05-1% of the solvent mass.

[0008] Preferably, the solvent is deionized water, the thickener is sodium carboxymethyl cellulose, and the binder is one or more of styrene-butadiene rubber, polyacrylic acid, and polyimide; The negative electrode active material is one or more of artificial graphite, natural graphite, silicon-carbon composite material, silicon-oxygen composite material, and lithium titanate.

[0009] The present invention also provides a method for preparing the above-described electrolyte-based defoaming battery slurry, comprising the following steps: S1. Dissolve the thickener in a solvent and stir to prepare a glue solution; S2. Add a conductive agent to the adhesive solution in S1 and perform dispersion treatment to obtain a conductive slurry; S3. Add negative electrode active material to the conductive paste of S2 and disperse it to obtain a mixed paste; S4. Add a binder to the mixed slurry of S3 and perform dispersion treatment to obtain the slurry to be defoamed; S5. Add defoamer to the slurry to be defoamed in S4, defoam under stirring, filter after defoaming to obtain defoamed battery slurry.

[0010] Preferably, in S1, the stirring conditions are: 30 rpm for revolution, 1500 rpm for rotation, and 4 hours.

[0011] Preferably, in S2, the conditions for dispersion processing are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

[0012] Preferably, in S3, the conditions for dispersion processing are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

[0013] Preferably, in S4, the conditions for dispersion processing are: revolution at 30 rpm, rotation at 500 rpm, and time of 30 min.

[0014] Preferably, in S5, the revolution is 30 rpm, the rotation is 0 rpm, the stirring time is 15 min, and the sieve mesh size is 200 mesh.

[0015] The present invention also provides the application of electrolyte-based defoaming battery slurry, wherein the above-mentioned electrolyte-based defoaming battery slurry is used to prepare a negative electrode sheet, and a lithium-ion battery containing the negative electrode sheet is prepared.

[0016] Therefore, the present invention, by employing the above-mentioned electrolyte-based defoaming battery slurry, its preparation method, and its application, has the following beneficial effects: (1) In situ compatible and without side effects: Tributyl phosphate, triethyl phosphate and diethyl carbonate used in this invention are the core solvent components of lithium-ion battery electrolyte. After they are introduced into the slurry as defoamers, they can be completely integrated into the electrolyte system during electrode drying and subsequent electrolyte injection, thus completely eliminating the risk of external defoamers poisoning electrochemical performance.

[0017] (2) Excellent defoaming efficiency: Compared with traditional NMP (N-methylpyrrolidone) additives or ordinary alcohol defoamers, tributyl phosphate, triethyl phosphate and diethyl carbonate have extremely low surface tension, which can quickly pierce the bubble wall on the surface of the slurry, and the defoaming speed is significantly improved.

[0018] (3) Reduce costs and simplify processes: Since the defoamer itself is an electrolyte component, there is no need to worry about residue issues. The complex vacuum defoaming process before coating can be eliminated, significantly reducing manufacturing costs.

[0019] (4) Improve interface stability: The residual trace amount of defoamer on the negative electrode surface helps the electrolyte to wet and improve the lithium ion transport channel, thereby improving the consistency of battery performance.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is an appearance diagram of the negative electrode sheet obtained by preparing the defoaming battery slurry based on electrolyte according to the present invention, its preparation method, and application example 1. Figure 2 This is an appearance diagram of the defoaming battery slurry based on electrolyte of the present invention, its preparation method, and the negative electrode sheet prepared by applying the battery slurry of Comparative Example 3. Detailed Implementation

[0022] This invention provides an electrolyte-based defoaming battery slurry, comprising the following raw materials by weight: 80-98 parts of negative electrode active material, 0.5-5 parts of conductive agent, 0.5-3 parts of thickener, 0.5-5 parts of binder, 40-120 parts of solvent, and 0.01-1 parts of defoamer, wherein the defoamer is one or more of tributyl phosphate, triethyl phosphate, and diethyl carbonate.

[0023] In this invention, the defoamer accounts for 0.05-1% of the solvent mass.

[0024] In this invention, the solvent is deionized water, the thickener is sodium carboxymethyl cellulose, and the binder is one or more of styrene-butadiene rubber, polyacrylic acid, and polyimide. The negative electrode active material is one or more of artificial graphite, natural graphite, silicon-carbon composite material, silicon-oxygen composite material, and lithium titanate.

[0025] The present invention also provides a method for preparing the above-described electrolyte-based defoaming battery slurry, comprising the following steps: S1. Dissolve the thickener in a solvent and stir to prepare a glue solution; S2. Add a conductive agent to the adhesive solution in S1 and perform dispersion treatment to obtain a conductive slurry; S3. Add negative electrode active material to the conductive paste of S2 and disperse it to obtain a mixed paste; S4. Add a binder to the mixed slurry of S3 and perform dispersion treatment to obtain the slurry to be defoamed; S5. Add defoamer to the slurry to be defoamed in S4, defoam under stirring, filter after defoaming to obtain defoamed battery slurry.

[0026] In this invention, in S1, the stirring conditions are: 30 rpm revolution, 1500 rpm rotation, and 4 hours.

[0027] In this invention, the conditions for dispersion processing in S2 are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

[0028] In this invention, the conditions for dispersion processing in S3 are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

[0029] In this invention, the conditions for dispersion processing in S4 are: revolution at 30 rpm, rotation at 500 rpm, and time of 30 min.

[0030] In this invention, in step S5, the revolution is 30 rpm, the rotation is 0 rpm, the stirring time is 15 min, and the filter screen has a mesh size of 200 mesh.

[0031] The present invention also provides the application of electrolyte-based defoaming battery slurry, wherein the above-mentioned electrolyte-based defoaming battery slurry is used to prepare a negative electrode sheet, and a lithium-ion battery containing the negative electrode sheet is prepared.

[0032] Furthermore, the negative electrode sheet includes a current collector and a negative electrode coating disposed on the surface of the current collector. The negative electrode coating is prepared by coating and drying the battery slurry described above. The residual amount of defoamer in the dried negative electrode coating is 0.01%-0.5%.

[0033] Furthermore, the defoamer is miscible with the electrolyte of the lithium-ion battery in the subsequent electrolyte injection process and forms a stable SEI film at the negative electrode interface.

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0035] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0036] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0037] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0038] Example 1 This invention provides an electrolyte-based defoaming battery slurry, the preparation method of which includes the following steps: First, 1.5 kg of sodium carboxymethyl cellulose (CMC) was added to 112 kg of deionized water and stirred for 4 hours at a revolution speed of 30 rpm and a rotation speed of 1500 rpm to prepare the adhesive solution. Then, 1.5 kg of superconducting carbon black (SP) was added to the obtained adhesive solution, and the solution was dispersed for 60 minutes by revolution at 30 rpm and rotation at 2000 rpm to achieve uniform dispersion of the conductive agent. Next, 95 kg of artificial graphite was added as the negative electrode active material and dispersed for 60 minutes at a high shear rate of 30 rpm revolution and 2000 rpm rotation. Then, 4.2 kg of styrene-butadiene rubber (SBR) emulsion was added to the mixed slurry, and the mixture was stirred at 30 rpm and 500 rpm for 30 minutes to ensure the stability of the slurry system. Finally, 0.56 kg of tributyl phosphate (TBP) was added as an endogenous defoamer to serve as an electrolyte component. The mixer speed was adjusted to 30 rpm for revolution and 0 rpm for slow stirring and defoaming treatment for 15 minutes. After filtration through a 200-mesh sieve, the battery slurry was obtained.

[0039] Example 2 The only difference between this embodiment and Example 1 is that the defoamer is diethyl carbonate; all other conditions are the same.

[0040] Example 3 The only difference between this comparative example and Example 1 is that the defoamer is triethyl phosphate; all other conditions are the same.

[0041] Comparative Example 1 The only difference between this comparative example and Example 1 is that the defoamer is N-methylpyrrolidone (NMP), while all other conditions are the same.

[0042] Comparative Example 2 The only difference between this comparative example and Example 1 is that the defoamer is n-butanol; all other conditions are the same.

[0043] Comparative Example 3 The only difference between this comparative example and Example 1 is that no defoamer was added during the preparation process; all other conditions were the same.

[0044] The slurries prepared in Example 1 and Comparative Example 3 were respectively formulated to have an areal capacity of 5.4 mAh / cm³. 2 The graphite anode sheets have the following appearances: Figure 1 and Figure 2 As shown, by Figure 1 and Figure 2 It can be seen that after defoaming treatment with the preferred defoamer of the present invention, tributyl phosphate (TBP), the surface of the prepared negative electrode sheet is uniform, flat and free of bubble defects, indicating that the defoamer can effectively eliminate bubbles in the slurry, thereby obtaining a high-quality coating appearance.

[0045] Performance testing: The battery slurries prepared in Examples 1-3 and Comparative Examples 1-3 were used to prepare a sample with an areal capacity of 5.4 mAh / cm². 2 The graphite anode sheet is configured with an area capacity of 4.5 mAh / cm². 2 The 811 ternary cathode sheet was used to assemble the cathode sheet, anode sheet, PP separator and electrolyte to obtain CR2025 coin cell lithium-ion full battery. The 1C cycle performance was tested and the test results are shown in Table 1.

[0046] Table 1 Test Results

[0047] As shown in Table 1, Examples 1, 2 and 3 all exhibited bubble-free coating appearance, with initial coulombic efficiencies of 88.5%, 89.7% and 88.4% respectively, and capacity retention rates of 92%, 93% and 90% after 500 cycles, respectively, which were the best among all samples.

[0048] While Comparative Example 1 (NMP) also has a certain defoaming effect, its cycle retention rate of 88% and first-run efficiency of 87.2% are both lower than those of the Example.

[0049] While Comparative Example 2 (n-butanol) achieved a bubble-free appearance, its initial efficiency (84.3%) and cycle retention (83%) were significantly low, indicating that defoamers not specified in this invention cannot simultaneously achieve both defoaming and electrochemical performance. Comparative Example 3 (without any defoamer) exhibited a large number of bubbles, with an initial efficiency of only 81% and a 500-cycle retention rate that plummeted to 67%, making it the worst. Therefore, selecting tributyl phosphate, triethyl phosphate, or diethyl carbonate as defoamers not only effectively eliminates bubbles in the slurry and improves the coating appearance but also simultaneously enhances the initial efficiency and long-cycle stability of lithium-ion batteries, achieving a dual optimization of defoaming and electrochemical performance.

[0050] Therefore, this invention employs the aforementioned electrolyte-based defoaming battery slurry, its preparation method, and its application. By adding a specific type of defoamer in the later stages of battery slurry preparation, bubbles in the slurry can be efficiently eliminated, resulting in a bubble-free coating appearance and significantly improving the coating quality and consistency of the negative electrode sheet. Simultaneously, the selected defoamer is a commonly used component in electrolytes, exhibiting good compatibility with the battery system and avoiding any adverse effects on electrochemical performance. Instead, it helps improve the initial coulombic efficiency and long-term cycle stability of lithium-ion batteries. Furthermore, this defoaming method is simple to operate, easy to industrialize, and avoids the performance degradation problems that may arise from traditional defoamers, achieving synergistic optimization of defoaming effect and battery performance.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An electrolyte-based defoaming battery slurry, characterized in that: By weight, it includes the following raw materials: 80-98 parts of negative electrode active material, 0.5-5 parts of conductive agent, 0.5-3 parts of thickener, 0.5-5 parts of binder, 40-120 parts of solvent, and 0.01-1 parts of defoamer, wherein the defoamer is one or more of tributyl phosphate, triethyl phosphate, and diethyl carbonate.

2. The electrolyte-based defoaming battery slurry according to claim 1, characterized in that: The defoamer accounts for 0.05-1% of the solvent mass.

3. The electrolyte-based defoaming battery slurry according to claim 1, characterized in that: The solvent is deionized water, the thickener is sodium carboxymethyl cellulose, and the binder is one or more of styrene-butadiene rubber, polyacrylic acid, and polyimide. The negative electrode active material is one or more of artificial graphite, natural graphite, silicon-carbon composite material, silicon-oxygen composite material, and lithium titanate.

4. The method for preparing the electrolyte-based defoaming battery slurry according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Dissolve the thickener in a solvent and stir to prepare a glue solution; S2. Add a conductive agent to the adhesive solution in S1 and perform dispersion treatment to obtain a conductive slurry; S3. Add negative electrode active material to the conductive paste of S2 and disperse it to obtain a mixed paste; S4. Add a binder to the mixed slurry of S3 and perform dispersion treatment to obtain the slurry to be defoamed; S5. Add defoamer to the slurry to be defoamed in S4, defoam under stirring, filter after defoaming to obtain defoamed battery slurry.

5. The method for preparing the electrolyte-based defoaming battery slurry according to claim 4, characterized in that: In S1, the stirring conditions are: 30 rpm revolution, 1500 rpm rotation, and 4 hours.

6. The method for preparing the electrolyte-based defoaming battery slurry according to claim 4, characterized in that: In S2, the conditions for decentralized processing are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

7. The method for preparing the electrolyte-based defoaming battery slurry according to claim 4, characterized in that: In S3, the conditions for decentralized processing are: revolution at 30 rpm, rotation at 2000 rpm, and time of 60 min.

8. The method for preparing the electrolyte-based defoaming battery slurry according to claim 4, characterized in that: In S4, the conditions for decentralized processing are: revolution at 30 rpm, rotation at 500 rpm, and time of 30 min.

9. The method for preparing the electrolyte-based defoaming battery slurry according to claim 4, characterized in that: In S5, the revolution speed is 30 rpm, the rotation speed is 0 rpm, the stirring time is 15 min, and the filter screen has a mesh size of 200 mesh.

10. The application of electrolyte-based defoaming battery slurry, characterized in that: A negative electrode sheet is prepared by using the electrolyte-based defoaming battery slurry according to any one of claims 1-3, and a lithium-ion battery containing the negative electrode sheet is prepared.

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