Carbon-coated slurry for improving performance of carbon-coated aluminum foil, current collector, pole piece and battery

Abstract

The invention discloses a carbon-coated slurry for improving the performance of a carbon-coated aluminum foil, a current collector, a pole piece and a battery, the carbon-coated slurry comprises a conductive agent, a dispersing agent and a binder, and the dispersing agent adopts poly (ethyleneimine-co-ethyl phosphate). The poly (ethyleneimine-co-ethyl phosphate) dispersing agent has the advantages that the bonding performance is enhanced, the effect of improving the conductivity is achieved, solid particles such as a carbon material can be promoted to be uniformly dispersed in carbon-coated aluminum foil slurry, particle aggregation is prevented, the stability and uniformity of the slurry are improved, the raw materials are easy to obtain, the reaction condition is mild, the operation process is simple and convenient, and the method is suitable for industrial production. The method is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a carbon-coated slurry, current collector, electrode, and battery for improving the performance of carbon-coated aluminum foil. Background Technology

[0002] Currently, there are several problems with dispersants used in carbon-coated aluminum foil pastes on the market: some traditional dispersants have poor dispersion effects, failing to maintain uniform dispersion of carbon materials in the paste for extended periods; some dispersants have poor compatibility with other components in the paste, affecting the overall performance of the paste; and others may introduce impurities during the preparation process, adversely affecting the electrochemical performance of the battery. Therefore, developing a high-performance dispersant for carbon-coated aluminum foil pastes is of great significance.

[0003] Carbon-coated aluminum foil plays a crucial role in lithium-ion batteries, effectively reducing internal resistance and improving charge / discharge efficiency and cycle performance. The properties of the slurry are paramount in the preparation of carbon-coated aluminum foil. The dispersion of solid particles such as carbon materials in the slurry directly affects the slurry's stability and coating effect. Uneven dispersion can lead to carbon material agglomeration, resulting in inconsistent coating thickness and negatively impacting battery performance. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon-coated slurry, current collector, electrode, and battery that improve the performance of carbon-coated aluminum foil, thereby improving battery performance through optimization of the dispersant in the carbon-coated slurry.

[0005] This invention is achieved through the following technical solution: The first aspect of this application provides a carbon coating paste for improving the performance of carbon-coated aluminum foil, comprising a conductive agent, a dispersant, and a binder, wherein the dispersant is poly(ethyleneimine-co-ethyl phosphate).

[0006] To optimize the above technical solution, the specific limitations also include: The poly(ethyleneimine-co-ethyl phosphate) is made of ethyleneimine monomer and ethyl phosphate monomer, with a molar ratio of ethyleneimine monomer to ethyl phosphate monomer of 1:1~3.

[0007] In the carbon coating slurry, the dispersant accounts for 3.8% to 7.4% by mass, preferably 4.7% to 6.5%.

[0008] Furthermore, the preparation method of the poly(ethyleneimine-co-ethyl phosphate) includes the following steps: S1: Mix the ethyleneimine monomer, ethyl phosphate monomer, and solvent evenly; S2: Add initiator and heat to react; S3: Pour the reaction mixture into the precipitant to precipitate the polymerization product, wash and dry to obtain poly(ethyleneimine-co-ethyl phosphate).

[0009] The amount of initiator used is 0.5-2% of the total mass of ethyleneimine monomer and ethyl phosphate monomer.

[0010] In step S1, methanol is used as the solvent; the total concentration of the ethyleneimine monomer and ethyl phosphate monomer is 0.1~0.2 g / ml.

[0011] The reaction conditions for step S2 are to heat to 50~80℃ and react for 4~7 hours; in step S3, ethanol is used as the precipitant, and the total mass of the reaction mixture to the volume ratio of the precipitant is 1:0.5~2 g / ml.

[0012] The second aspect of this application provides a carbon-coated functional current collector, which is prepared by coating an aluminum current collector with the aforementioned carbon-coated slurry that improves the performance of carbon-coated aluminum foil.

[0013] A third aspect of this application provides an electrode comprising the aforementioned carbon-coated functional current collector.

[0014] A fourth aspect of this application provides a battery comprising the aforementioned electrode.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a poly(ethyleneimine-co-ethyl phosphate) dispersant for carbon-coated aluminum foil paste, which promotes the uniform dispersion of solid particles such as carbon materials in the carbon-coated aluminum foil paste, prevents particle agglomeration, and improves the stability and uniformity of the paste. This dispersant has the following characteristics when applied to carbon-coated aluminum foil paste: Enhanced adhesion: This dispersant acts as a bridge between the carbon material and the aluminum foil, enhancing the adhesion between the two through chemical bonding and physical adsorption, making the coating adhere more firmly to the aluminum foil surface, thereby improving the overall performance and service life of the carbon-coated aluminum foil.

[0016] Improved conductivity: The uniform dispersion of carbon materials helps to build a continuous conductive network, thereby improving the conductivity of carbon-coated aluminum foil, reducing battery internal resistance, and improving battery charge and discharge efficiency and cycle performance.

[0017] The raw materials for preparing the dispersant of the present invention are readily available, the reaction conditions are mild, the operation process is simple, and it is suitable for large-scale industrial production. Detailed Implementation The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0018] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the reagents, methods and equipment used are conventional reagents, methods and equipment in this technical field.

[0019] For the sake of brevity, this article only discloses some numerical values ​​and the range of options. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range; the options in the range of options can also be combined arbitrarily.

[0020] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art.

[0021] This invention provides a carbon coating paste for improving the performance of carbon-coated aluminum foil, comprising a conductive agent, a dispersant, and a binder, wherein the dispersant is poly(ethyleneimine-co-ethyl phosphate).

[0022] Poly(ethyleneimine-co-ethyl phosphate) is made of ethyleneimine monomer and ethyl phosphate monomer, with a molar ratio of ethyleneimine monomer to ethyl phosphate monomer of 1:1~3.

[0023] In the carbon coating slurry, the mass percentage of dispersant is 3.8% to 7.4%, preferably 4.7% to 6.5%.

[0024] In some embodiments, the preparation method of poly(ethyleneimine-co-ethyl phosphate) includes the following steps: S1: Mix the ethyleneimine monomer, ethyl phosphate monomer, and solvent evenly; S2: Add initiator and heat to react; S3: Pour the reaction mixture into the precipitant to precipitate the polymerization product, wash and dry to obtain poly(ethyleneimine-co-ethyl phosphate).

[0025] The amount of initiator used is 0.5-2% of the total mass of ethyleneimine monomer and ethyl phosphate monomer.

[0026] In step S1, methanol is used as the solvent; the total concentration of ethyleneimine monomer and ethyl phosphate monomer is 0.1~0.2 g / ml.

[0027] The reaction conditions for step S2 are to heat to 50~80℃ and react for 4~7 hours; in step S3, ethanol is used as the precipitant, and the total mass of the reaction mixture to the volume ratio of the precipitant is 1:0.5~2 g / ml.

[0028] Take a specific carbon coating paste preparation process as an example: (1) Preparation of poly(ethyleneimine-co-ethyl phosphate): Raw material preparation: Prepare appropriate amounts of ethyleneimine monomer, ethyl phosphate monomer, initiator (azobisisobutyronitrile), and solvent (methanol).

[0029] Polymerization reaction: In a reaction vessel, a certain amount of solvent is added, nitrogen gas is introduced to remove air, ethyleneimine monomer and ethyl phosphate monomer are added to the solvent in a certain molar ratio and stirred evenly; then the initiator is added, and the temperature is raised to 50~80℃ to carry out the polymerization reaction for 4~7 hours.

[0030] Post-processing: After the reaction is complete, the reaction solution is poured into a precipitant (ethanol) to precipitate the polymer; the precipitate is filtered, collected, washed several times with ethanol to remove impurities, and then dried in a vacuum drying oven at 50~60℃ to constant weight to obtain poly(ethyleneimine-co-ethyl phosphate).

[0031] (2) Mix poly(ethyleneimine-co-ethyl phosphate), conductive agent and binder in proportion to prepare carbon coating paste.

[0032] The dispersant used in the carbon coating slurry of the present invention is poly(ethyleneimine-co-ethyl phosphate), which can effectively prevent particle aggregation, play a good dispersing role in slurry systems with high solid content, significantly reduce slurry viscosity, improve slurry stability and rheology, improve the dispersibility and stability of solid particles such as carbon materials in carbon-coated aluminum foil slurry, and improve the performance of carbon-coated aluminum foil.

[0033] The present invention also provides a carbon-coated functional current collector, wherein the carbon-coating slurry for improving the performance of carbon-coated aluminum foil is coated on an aluminum current collector to prepare a functional current collector containing a carbon coating layer.

[0034] In some embodiments, the prepared carbon coating slurry is uniformly coated onto the surface of the aluminum current collector using methods such as blade coating, slot extrusion coating, microgravure coating, spraying, and dip-coating, and then dried. Among them, the aluminum current collector is a pure aluminum foil or a functional current collector with a dense aluminum layer surface.

[0035] The preferred drying conditions are: drying in an oven at 90~120℃ for 2~4 hours, preferably obtaining a coating with a thickness of 1.6~2.5 micrometers after drying.

[0036] The present invention also provides an electrode comprising the above-described carbon-coated functional current collector.

[0037] The present invention also provides a battery comprising the above-described electrode.

[0038] The technical solution of the present invention will be further described in detail below with reference to specific embodiments: Example 1 Preparation of poly(ethyleneimine-co-ethyl phosphate) dispersant: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, 200 mL of methanol was added, and nitrogen gas was purged for 30 minutes to remove air; 10 g of ethyleneimine monomer and 20 g of ethyl phosphate monomer were added and stirred until homogeneous; then 0.2 g of azobisisobutyronitrile initiator was added, and the temperature was raised to 60 °C and reacted for 5 hours; after the reaction was completed, the reaction solution was poured into 500 mL of ethanol, and polymer precipitate was formed; the precipitate was filtered, collected, washed three times with 100 mL of ethanol each time, and then dried in a vacuum drying oven at 55 °C to constant weight to obtain poly(ethyleneimine-co-ethyl phosphate) dispersant.

[0039] Preparation and coating of carbon-coated aluminum foil slurry: A general-purpose carbon-coated slurry (2 kg) was prepared by mixing binder (polyacrylic acid), conductive graphite (KS6), conductive carbon black (Li-400), and solvent (self-made pure water) in a mass ratio of 1:0.5:0.5:5:93. This slurry was then divided into 10 equal portions, each weighing 200 g. One portion of the slurry was randomly selected, and 10 g of poly(ethyleneimine-co-ethyl phosphate) dispersant (i.e., the dispersant accounted for 4.76% of the slurry mass fraction) was added. The mixture was stirred at 1500 rpm for 1.5 hours in a high-speed stirrer until fully dissolved. The prepared carbon-coated aluminum foil slurry was then uniformly coated onto the surface of a 12-micron 1100 alloy aluminum foil using a scraping method. The foil was dried in an oven at 100℃ for 3 hours, resulting in a coating thickness of 2 microns and a coating basis weight of 1 g / m². 2 Carbon-coated aluminum foil.

[0040] Performance testing: The penetration resistance of the carbon-coated aluminum foil was tested using a Chuanyuan Technology electrode resistance meter; the adhesion strength was tested using a Chuanyuan Technology horizontal electronic peel tester.

[0041] The results of the adhesion and resistance tests are shown in Table 1.

[0042] Example 2 This embodiment adopts a scheme that is basically the same as that in Example 1, except that the amount of poly(ethyleneimine-co-ethyl phosphate) dispersant added to a 200g portion of carbon coating slurry is 4g (i.e., the dispersant accounts for 1.96% of the slurry mass fraction).

[0043] Example 3 This embodiment adopts a scheme that is basically the same as that in Example 1, except that the amount of poly(ethyleneimine-co-ethyl phosphate) dispersant added to a 200g portion of carbon coating slurry is 8g (i.e., the dispersant accounts for 3.85% of the slurry mass fraction).

[0044] Example 4 This embodiment adopts a scheme that is basically the same as that in Example 1, except that the amount of poly(ethyleneimine-co-ethyl phosphate) dispersant added to a 200g portion of carbon coating slurry is 12g (i.e., the dispersant accounts for 5.66% of the slurry mass fraction).

[0045] Example 5 This embodiment adopts a scheme that is basically the same as that in Example 1, except that the amount of poly(ethyleneimine-co-ethyl phosphate) dispersant added to a 200g portion of carbon coating slurry is 14g (i.e., the dispersant accounts for 6.54% of the slurry mass fraction).

[0046] Example 6 This embodiment adopts a scheme that is basically the same as that in Example 1, except that the amount of poly(ethyleneimine-co-ethyl phosphate) dispersant added to a 200g portion of carbon coating slurry is adjusted to 16g (i.e., the dispersant accounts for 7.41% of the slurry mass fraction).

[0047] Comparative Example 1 In this comparative example, no poly(ethyleneimine-co-ethyl phosphate) dispersant was added to the carbon coating slurry, and all other steps and parameters were the same as in Example 1.

[0048] Comparative Example 2 In this comparative example, CMC was used instead of poly(ethyleneimine-co-ethyl phosphate) dispersant in the carbon coating slurry, and the remaining steps and parameters were the same as in Example 1.

[0049] Table 1. Test results of the examples and comparative examples.

[0050] As can be seen from the test data in Table 1, poly(ethyleneimine-co-ethyl phosphate) dispersant has a significant effect on the resistance and peel force of carbon-coated aluminum foil. Compared with the comparative examples, the present invention can improve the electrode peel force while reducing resistance by adding poly(ethyleneimine-co-ethyl phosphate).

[0051] The poly(ethyleneimine-co-ethyl phosphate) in the carbon coating slurry of the present invention can achieve maximum improvement within a certain range: The resistance of Examples 1-6 is better than that of Comparative Example 1 (without dispersant) and Comparative Example 2 (with CMC substitution); the peel strength of Examples 1-6 is much higher than that of Comparative Example 1 (without dispersant) and Comparative Example 2 (with CMC substitution).

[0052] Example 2 showed a slightly higher resistance compared to Example 1. The low dispersant content may have resulted in an insufficiently continuous conductive network. The resistances of Examples 3-6 remained stable in the range of 2.31-2.56 mΩ, with Example 6 exhibiting the lowest resistance. This indicates that a high dispersant content helps optimize the conductive network and reduce resistance. Comparative Examples 1 and 2, without dispersant or using CMC, showed significantly higher resistances than the Example groups, confirming that poly(ethyleneimine-co-ethyl phosphate) dispersant can effectively improve conductivity.

[0053] Examples 1 and 4 showed a balance in resistance and peel force, with resistance close to 2.5 mΩ and peel force exceeding 770 N / m; Example 6 had the lowest resistance but a slightly lower peel force, possibly due to excessive dispersant leading to an overly thick interfacial layer, which partially weakened the bond strength.

[0054] In summary, the poly(ethyleneimine-co-ethyl phosphate) dispersant used in this invention can significantly improve the conductivity and adhesion of carbon-coated aluminum foil. Its content should be controlled within the preferred range of 4.7-6.5% to avoid performance fluctuations.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A carbon coating paste for improving the performance of carbon-coated aluminum foil, characterized in that: It includes a conductive agent, a dispersant, and a binder, wherein the dispersant is poly(ethyleneimine-co-ethyl phosphate).

2. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: The poly(ethyleneimine-co-ethyl phosphate) is made of ethyleneimine monomer and ethyl phosphate monomer, with a molar ratio of ethyleneimine monomer to ethyl phosphate monomer of 1:1~3.

3. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: In the carbon coating slurry, the dispersant accounts for 3.8% to 7.4% by mass, preferably 4.7% to 6.5%.

4. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: The preparation method of the poly(ethyleneimine-co-ethyl phosphate) includes the following steps: S1: Mix the ethyleneimine monomer, ethyl phosphate monomer, and solvent evenly; S2: Add initiator and heat to react; S3: Pour the reaction mixture into the precipitant to precipitate the polymerization product, wash and dry to obtain poly(ethyleneimine-co-ethyl phosphate).

5. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: The amount of initiator used is 0.5-2% of the total mass of ethyleneimine monomer and ethyl phosphate monomer.

6. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: In step S1, methanol is used as the solvent; the total concentration of the ethyleneimine monomer and ethyl phosphate monomer is 0.1~0.2 g / ml.

7. The carbon coating paste for improving the performance of carbon-coated aluminum foil according to claim 1, characterized in that: The reaction conditions for step S2 are to heat to 50~80℃ and react for 4~7 hours; in step S3, ethanol is used as the precipitant, and the total mass of the reaction mixture to the volume ratio of the precipitant is 1:0.5~2 g / ml.

8. A carbon-coated functional current collector, characterized in that: A functional current collector containing a carbon coating layer is prepared by coating an aluminum current collector with a carbon coating slurry according to any one of claims 1 to 7 to improve the performance of carbon-coated aluminum foil.

9. An electrode sheet, characterized in that: It includes the carbon-coated functional current collector as described in claim 8.

10. A battery, characterized in that: It includes the electrode sheet as described in claim 9.

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