A carbon-coated current collector water-based carbon coating slurry, its preparation method and application

Abstract

This invention provides an aqueous carbon coating slurry for carbon-coated current collectors, its preparation method, and its application. The aqueous carbon coating slurry comprises a conductive agent, an aqueous binder, functional additives, a pH adjuster, and a solvent. The functional additives include a metal-organic framework crystal precursor composition formed by a silane derivative with a long-chain polyether segment and / or zinc salts and imidazole ligands. This invention provides an interface-reinforcing slurry with strong process compatibility, capable of significantly improving the tensile strength of carbon-coated current collectors and optimizing their mechanical behavior. During the preparation of the carbon coating layer, the functional additives contained in this slurry can react in situ with impurities on the surface of the current collector substrate to form a high-strength interface-reinforcing layer, improving the overall rigidity and dimensional stability of the current collector. Therefore, without significantly altering existing aqueous carbon coating processes, this invention achieves a fundamental enhancement of the mechanical properties of the current collector, effectively improving the processing yield and cycle stability of battery electrodes.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material technology, specifically relating to a carbon-coated current collector water-based carbon coating slurry, its preparation method, and its application. Background Technology

[0002] The positive electrode current collector of lithium-ion batteries typically uses carbon-coated aluminum foil (i.e., a carbon coating layer is applied to the surface of aluminum foil). This foil must withstand mechanical stresses such as rolling and slitting during battery manufacturing, and resist internal stresses caused by volume changes in the active material during battery cycling. Impurities such as Fe and Si present in the aluminum foil substrate often exist as brittle phases like oxides on the surface, becoming stress concentration points and weak points in mechanical properties.

[0003] Currently, methods to improve the mechanical properties of carbon-coated aluminum foil mainly focus on optimizing the alloy composition and annealing process of the aluminum foil itself, or selecting more flexible binders. However, these methods are costly and do not effectively address the microscopic mechanical weakness of the "impurity-interface". The tensile strength of conventional carbon-coated aluminum foil is usually around 200 MPa, and it has a certain degree of plasticity (elongation of about 3.5%). Therefore, in high-pressure solid electrodes or long-cycle applications, it may lead to excessive stretching of the electrode or failure of the carbon coating layer due to substrate yielding, thereby affecting the long-term cycle stability and safety of the battery.

[0004] Therefore, how to fundamentally strengthen the interfacial bonding between the current collector substrate and the carbon coating layer, and improve the overall rigidity and dimensional stability of the current collector, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an aqueous carbon coating slurry for carbon-coated current collectors, its preparation method, and its application. This invention provides an interface-reinforcing slurry with strong process compatibility, capable of significantly improving the tensile strength of carbon-coated current collectors and optimizing their mechanical behavior. During the preparation of the carbon coating layer, the functional additives contained in this slurry can react in situ with impurities on the surface of the current collector substrate to form a high-strength interface-reinforcing layer. This reaction transforms impurities, which were originally mechanical weaknesses, into strengthening points, achieving a "waste-to-treasure" interface-reinforcing effect. It solves the interface-reinforcing problem at the microscopic level, significantly improving the overall rigidity and dimensional stability of the current collector. Therefore, without fundamentally altering existing aqueous carbon coating processes, this invention achieves a fundamental enhancement of the mechanical properties of the current collector, effectively improving the processing yield and cycle stability of battery electrodes.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an aqueous carbon coating slurry for carbon-coated current collectors, the aqueous carbon coating slurry comprising a conductive agent, an aqueous binder, a functional additive, a pH adjuster, and a solvent.

[0007] The functional additives include silane derivatives having long-chain polyether segments and / or metal-organic framework crystal precursor compositions formed by zinc salts and imidazole ligands.

[0008] This invention provides an interface-reinforcing slurry with strong process compatibility, capable of significantly improving the tensile strength of carbon-coated current collectors and optimizing their mechanical behavior. During the preparation of the carbon coating layer, the functional additives contained in this slurry can react in situ with impurities on the surface of the current collector substrate, forming a high-strength interface-reinforcing layer. This reaction transforms impurities, which were originally mechanical weaknesses, into strengthening points, achieving a "turning waste into treasure" interface-reinforcing effect. This solves the interface-reinforcing problem at the microscopic level, significantly improving the overall rigidity and dimensional stability of the current collector. Therefore, without fundamentally altering existing water-based carbon coating processes, this invention achieves a fundamental enhancement of the mechanical properties of the current collector, effectively improving the processing yield and cycle stability of battery electrodes.

[0009] In this invention, the core of the silane derivative with long-chain polyether segments is "flexible bridging of organic molecules." It achieves chemical anchoring by forming strong covalent bonds between the terminal silane groups and impurity oxides on the surface of the current collector substrate. Simultaneously, its long-chain polyether segments form a dense hydrogen bond network with the water-based binder. This structure in situ constructs a microscopic viscoelastic buffer layer between the brittle impurities and the carbon coating layer. When subjected to external forces, this layer can efficiently dissipate energy and disperse stress through the extension and slippage of polymer chains and the reversible breakage / reorganization of hydrogen bonds, thereby preventing crack initiation and propagation. This significantly improves the fracture resistance and toughness of the carbon coating layer, representing a "softening the rigid" toughening strategy. The core of the metal-organic framework crystal precursor composition formed by zinc salt and imidazole ligand is the in-situ construction of rigid armor. During the preparation of the carbon coating layer, a coordination self-assembly reaction occurs directly on the surface of the current collector substrate, and a dense metal-organic framework crystal film is grown in situ. This hard nanocrystal is like a layer of "ceramic armor", which tightly wraps and bridges brittle impurity particles. When subjected to force, it can quickly homogenize the local concentrated stress to the entire continuous network, and consume energy through the micro-elastic deformation of its crystal structure and by forcing cracks to deflect and branch inside it, thereby greatly improving the load-bearing strength and resistance to damage of the interface. It is a "rigid-to-rigid" strengthening strategy.

[0010] Preferably, in the silane derivative having a long-chain polyether segment, the long-chain polyether segment includes any one or a combination of at least two of polyethylene glycol segments, polypropylene glycol segments, or polytetrahydrofuran.

[0011] In the silane derivative with long-chain polyether segments provided by this invention, the long-chain polyether segments form a dense hydrogen bond network with the water-based binder. When the carbon coating current collector is subjected to external force, this network can efficiently dissipate energy and disperse stress through the extension and slippage of polymer chains and the reversible breaking and recombination of hydrogen bonds, thereby preventing the initiation and propagation of cracks at the interface and significantly improving the fracture resistance and toughness of the carbon coating layer.

[0012] Preferably, the silane derivative having a long-chain polyether segment includes any one or a combination of at least two of polyetheramine triethoxysilane, polyetheramine trimethoxysilane, or polyetheramine triethoxysilane.

[0013] Preferably, the metal-organic framework crystal precursor composition includes any one or a combination of at least two of the ZIF-8 precursor, ZIF-67 precursor, or ZIF-11 precursor.

[0014] Preferably, the zinc salt comprises zinc nitrate.

[0015] Preferably, the imidazole ligand comprises 2-methylimidazole.

[0016] Preferably, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 2-6 wt%, for example, it can be 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%.

[0017] In this invention, the appropriate mass content of the functional additive can fully react in situ with impurities on the surface of the current collector substrate to form a high-strength interface reinforcement layer. This reaction transforms impurities, which were originally mechanical weaknesses, into strengthening points, achieving an interface reinforcement effect that "turns waste into treasure." This solves the interface reinforcement problem at the microscopic level and significantly improves the overall rigidity and dimensional stability of the current collector. If the addition amount is too low (e.g., below 2wt%), the interface reinforcement effect is not significant, and the increase in tensile strength is limited; if the addition amount is too high (e.g., above 6wt%), it may lead to increased slurry costs and excessive internal stress in the coating, which is detrimental to elongation control.

[0018] Preferably, the functional additive is a combination of the silane derivative and the metal-organic framework crystal precursor composition, wherein the mass ratio of the silane derivative and the metal-organic framework crystal precursor composition is (0.5-2):1, for example, it can be 0.5:1, 1:1, 1.5:1 or 2:1, etc.

[0019] Preferably, the conductive agent comprises conductive carbon black and / or graphite.

[0020] Preferably, the conductive agent comprises conductive carbon black and graphite, and the mass ratio of the conductive carbon black to graphite is (1-2):1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1 or 2:1, etc. For example, the graphite can be artificial graphite or natural graphite, etc.

[0021] This invention uses two conductive materials: conductive carbon black and graphite. The "dot" network of carbon black and the "sheet" network of graphite intertwine to form a three-dimensional conductive structure, which helps to further improve the conductivity of the carbon coating layer.

[0022] Preferably, the waterborne adhesive comprises any one or a combination of at least two of waterborne polyacrylic acid, waterborne polyurethane, or waterborne styrene-butadiene rubber.

[0023] Preferably, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the conductive agent is 50-70 wt%, for example, it can be 50 wt%, 55 wt%, 60 wt%, 65 wt%, or 70 wt%.

[0024] Preferably, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the water-based binder is 30-50%, for example, it can be 30%, 35%, 40%, 45% or 50%, etc.

[0025] Preferably, the pH of the aqueous carbon coating slurry is 6-8, for example, it can be 6, 6.5, 7, 7.5 or 8.

[0026] Preferably, the pH adjuster comprises sodium hydroxide.

[0027] Preferably, in the solid components of the water-based carbon coating slurry, the mass ratio of water-based binder, pH adjuster, and functional additive is (30-47):(50-67):(2-6), wherein the water-based binder is selected from the range "30-47", for example, 30, 35, 40, 45, or 47; the conductive agent is selected from the range "50-67", for example, 50, 55, 60, 65, or 67; and the functional additive is selected from the range "2-6", for example, 2, 3, 4, 5, or 6.

[0028] This invention controls the mass ratio of water-based binder, conductive agent and functional additive to (30-47):(50-67):(2-6). Under this ratio, the carbon coating layer can be ensured to have good conductive network integrity, coating flexibility and interface enhancement effect.

[0029] Preferably, the aqueous carbon coating slurry further includes a wetting agent. Examples include polyether siloxane, modified polyether siloxane, or alcohol reagents, such as isopropanol.

[0030] The main function of adding a wetting agent in this invention is to reduce the surface tension of the slurry and improve the quality of the coating film.

[0031] Preferably, the amount of wetting agent added is 8-12% of the total mass of the water-based carbon coating slurry, for example, it can be 8%, 9%, 10%, 11% or 12%, etc.

[0032] Preferably, the solid content of the water-based carbon coating slurry is 10-25 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, or 25 wt%.

[0033] In a second aspect, the present invention provides a method for preparing a water-based carbon coating slurry for carbon-coated current collectors as described in the first aspect, the preparation method comprising the following steps: A conductive agent, an aqueous binder, a functional additive, a pH adjuster, and a solvent are mixed to obtain the water-based carbon coating slurry for carbon coating current collectors; wherein the functional additive includes a composition of a metal-organic framework crystal precursor formed by a silane derivative having a long-chain polyether segment and / or a zinc salt and an imidazole ligand.

[0034] The method of adding functional additives in this invention does not change the existing process of preparing the carbon coating layer with water-based carbon coating slurry, resulting in low production and maintenance costs, which is conducive to its widespread use.

[0035] Preferably, a wetting agent is also added during the mixing process; Preferably, the mixing method includes: (a) The functional additives, water-based adhesive liquid and solvent are mixed to obtain the initial mixture.

[0036] (b) The conductive agent is added to the initial slurry in batches for mixing, and then the pH adjuster is added and mixed.

[0037] This invention premixes functional additives and water-based binder solutions, which allows the functional additives to be uniformly dispersed in the binder network. This ensures that the functional additives fully contact and react in situ with impurities on the surface of the current collector substrate during the subsequent coating and drying process. Then, the conductive agent is added in batches, which allows the conductive agent to be gradually and uniformly dispersed in the slurry, reducing the phenomenon of excessively high local concentrations. This results in a more stable and uniform slurry system, which helps to improve the conductivity consistency of the carbon coating layer.

[0038] Preferably, the preparation steps of the silane derivative having long-chain polyether segments include: In an inert atmosphere (e.g., nitrogen), a long-chain polyether alcohol and an organic solvent are mixed, and then a silane coupling agent containing isocyanate groups and a catalyst are added to carry out a grafting reaction to obtain the silane derivative having long-chain polyether segments.

[0039] Preferably, the long-chain polyether alcohol includes polyethylene glycol monomethyl ether.

[0040] Preferably, the organic solvent comprises tetrahydrofuran.

[0041] Preferably, the catalyst comprises dibutyltin dilaurate.

[0042] Preferably, the silane coupling agent containing isocyanate groups includes isocyanate propyltriethoxysilane.

[0043] Preferably, the reaction temperature is 40-50℃, for example, 40℃, 42℃, 45℃, 48℃ or 50℃, and the time is 4-6h, for example, 4h, 4.5h, 5h, 5.5h or 6h.

[0044] Preferably, when the silane derivative having a long-chain polyether segment is a polyetheramine-type triethoxysilane, the preparation steps include: In an inert atmosphere, polyethylene glycol monomethyl ether and tetrahydrofuran were stirred and mixed, then dibutyltin dilaurate catalyst was added, followed by dropwise addition of isocyanate propyltriethoxysilane solution. After the addition was complete, the mixture was stirred at 40-50°C for 4-6 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, and dried to obtain the polyetheramine triethoxysilane.

[0045] Preferably, the solid content of the water-based adhesive solution is 15-25 wt%, for example, it can be 15 wt%, 18 wt%, 20 wt%, 22 wt%, or 25 wt%.

[0046] Preferably, the viscosity of the water-based adhesive solution is 800-3000 mPa·s, for example, it can be 800 mPa·s, 1000 mPa·s, 1500 mPa·s, 2000 mPa·s, 2500 mPa·s or 3000 mPa·s, etc.

[0047] Preferably, the conductive agent is added to the initial mixed slurry in two batches, and the mass ratio of the first batch to the second batch is (0.4-0.6):(0.4-0.6). The range of the conductive agent in the first batch, "0.4-0.6", can be, for example, 0.4, 0.45, 0.5, 0.55, or 0.6. The range of the conductive agent in the second batch, "0.4-0.6", can be, for example, 0.4, 0.45, 0.5, 0.55, or 0.6.

[0048] Preferably, the mixing process in step (a) is accompanied by stirring, and the stirring rate is 2000-2200 rpm, for example, 2000 rpm, 2050 rpm, 2100 rpm, 2150 rpm or 2200 rpm.

[0049] Preferably, in step (b), the conductive agent is added to the initial slurry in batches while being stirred, and the stirring rate increases gradually with each batch of material added.

[0050] This invention involves adding the conductive agent in batches and gradually increasing the stirring rate with each batch. This allows the conductive agent to be dispersed gradually and evenly in the slurry, reducing the phenomenon of excessively high local concentrations. As a result, a more stable and uniform slurry system is obtained, which helps to improve the conductivity consistency of the carbon coating layer.

[0051] Preferably, the preparation method includes the following steps: (1) Mix water-based adhesive liquid with a viscosity of 800-3000 mPa·s and a solid content of 15-25 wt% with water, and disperse it at a stirring rate of 1000-1200 rpm (e.g., 1000 rpm, 1100 rpm or 1200 rpm, etc.) for 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min or 40 min, etc.) to obtain an adhesive dilution liquid with a solid content of 12-20 wt% (e.g., 12 wt%, 14 wt%, 16 wt%, 18 wt% or 20 wt%, etc.) and a viscosity of 500-2000 mPa·s (e.g., 500 mPa·s, 1000 mPa·s, 1500 mPa·s or 2000 mPa·s, etc.).

[0052] (2) Mix the functional additive with the binder dilution and disperse it at a stirring rate of 2000-2200 rpm for 5-15 min (e.g., 5 min, 8 min, 10 min, 12 min or 15 min, etc.) to obtain the initial slurry.

[0053] The functional additives include silane derivatives with long-chain polyether segments and / or metal-organic framework crystal precursor compositions formed by zinc salts and imidazole ligands. The preparation steps of the silane derivatives with long-chain polyether segments include: mixing long-chain polyether alcohols and organic solvents in an inert atmosphere, then adding silane coupling agents and catalysts containing isocyanate groups, and carrying out a grafting reaction at 40-50°C to obtain the silane derivatives with long-chain polyether segments.

[0054] (3) Add a conductive agent with a mass fraction of w1 to the initial slurry and disperse it for 20-40 minutes (e.g., 20 minutes, 25 minutes, 30 minutes, 35 minutes, or 40 minutes) at a stirring rate of 1500-1800 rpm (e.g., 1500 rpm, 1600 rpm, 1700 rpm, or 1800 rpm, etc.). Then add a conductive agent with a mass fraction of w2 and disperse it for 20-40 minutes (e.g., 2000 rpm, 2200 rpm, 2400 rpm, or 2600 rpm, etc.) at a stirring rate of 2000-2600 rpm (e.g., 2000 rpm, 2200 rpm, 2400 rpm, or 2600 rpm, etc.) to obtain an intermediate slurry. Wherein, w1:w2 = (0.4-0.6):(0.4-0.6), and w1+w2 = 1. The conductive agent includes conductive carbon black and graphite with a mass ratio of (1-2):1.

[0055] (4) Add water to the intermediate slurry until the solid content is 10-20wt% (e.g., 10wt%, 15wt%, or 20wt%), and disperse at a stirring rate of 2000-2600rpm (e.g., 2000rpm, 2200rpm, 2400rpm, or 2600rpm) for 20-40min (e.g., 20min, 25min, 30min, 35min, or 40min). Then add a pH adjuster to adjust the pH of the slurry system to 6-8, add a wetting agent, and disperse at a stirring rate of 10-15rpm (e.g., 10rpm, 11rpm, 12rpm, 13rpm, 14rpm, or 15rpm) for 30-45min. After that, perform homogenization treatment to obtain the carbon coating current collector water-based carbon coating slurry.

[0056] Preferably, during the homogenization process, the pressure is 500-700 bar, for example, 500 bar, 600 bar, or 700 bar.

[0057] The present invention does not limit the number of homogenization processes; for example, it may be 1 time, 2 times, or 3 times.

[0058] Thirdly, the present invention provides a carbon-coated current collector comprising a substrate and a carbon coating layer disposed on at least one surface of the substrate, the carbon coating layer being prepared using an aqueous carbon coating slurry as described in the first aspect.

[0059] The carbonized current collector prepared based on the water-based carbonized slurry provided by this invention has excellent material rigidity, yield strength and dimensional stability.

[0060] Preferably, the substrate comprises aluminum foil.

[0061] The present invention does not limit the preparation method of the carbon coating layer. For example, a slot coating method can be used to coat the surface of the aluminum foil with water-based carbon coating slurry, then dry and cure it, and finally cool and roll it up.

[0062] Fourthly, the present invention provides a lithium-ion battery, wherein the positive electrode of the lithium-ion battery includes a carbon-coated current collector as described in the third aspect.

[0063] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0064] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides an interface-reinforcing slurry with strong process compatibility, which can significantly improve the tensile strength of carbon-coated current collectors and optimize their mechanical behavior. During the preparation of the carbon coating layer, the functional additives contained in this slurry can react in situ with impurities on the surface of the current collector substrate to form a high-strength interface-reinforcing layer. This reaction transforms impurities, which were originally mechanical weaknesses, into strengthening points, achieving an interface-reinforcing effect that "turns waste into treasure." It solves the interface-reinforcing problem at the microscopic level and significantly improves the overall rigidity and dimensional stability of the current collector. Therefore, without fundamentally changing the existing water-based carbon coating process, this invention achieves a fundamental enhancement of the mechanical properties of the current collector, effectively improving the processing yield and cycle stability of the battery electrode.

[0065] (2) The preparation process of the water-based carbon coating slurry provided by the present invention is simple, and the addition of functional additives will not change the existing process of preparing the carbon coating layer of the water-based carbon coating slurry. The production cost is low, the maintenance cost is low, and it is easy to promote and use. Detailed Implementation

[0066] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0067] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0068] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0069] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0070] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0071] It should be noted that the specifications of the raw materials required for preparing polyetheramine-type triethoxysilane and ZIF-8 precursors in the following embodiments are as follows: ① Propyltriethoxysilane isocyanate, purchased from Sinopharm Group, model 95% (Wokai), 5g, Sinopharm code XW012480188501; ② Polyethylene glycol monomethyl ether, MW750, purchased from Sinopharm Group, model Acros-192320010, 1kg, Sinopharm code C192320010; ③ Tetrahydrofuran, purchased from Sinopharm Group, model CP (Shanghai Testing). ④ Dibutyltin dilaurate, purchased from Sinopharm Group, model TCI-D0303, 95.0% (W), 500g, national drug code TD0303500G; ⑤ Zinc nitrate hexahydrate, purchased from Sinopharm Group, model CP (Shanghai Test), ≥98.0%, 500g, national drug code 80141328; ⑥ 2-Methylimidazole, purchased from Sinopharm Group, model 98% (Wokai), 500g, national drug code XW069398131.

[0072] The specifications of the raw materials required for preparing the water-based carbon coating slurry in the following embodiments are as follows: ① Water-based polyacrylic acid (PAA), purchased from Linte Technology, model 7002; ② Solvent is deionized water, self-made; ③ Conductive carbon black, purchased from Cabot Chemical, model SHYT-150P; ④ Conventional graphite, purchased from Sinopharm Group, model: CP (Shanghai Test), ≥99.85%, 100g, Sinopharm code 20019126; ⑤ Isopropanol, purchased from Sinopharm Group, model is LC-MS (Shanghai Test), 4L, Sinopharm code 40064361; ⑥ Sodium hydroxide, purchased from Sinopharm Group, model is AR (Shanghai Test) (flakes), 500g, Sinopharm code 10019764; ⑦ Polyetheramine triethoxysilane, self-made.

[0073] Example 1 This embodiment provides an aqueous carbon coating slurry for carbon current collectors, which includes a conductive agent, an aqueous binder, a functional additive, a pH adjuster, a wetting agent, and deionized water.

[0074] The functional additive is a polyetheramine-type triethoxysilane; based on the total solid mass of the aqueous carbon coating slurry as 100%, the mass content of the functional additive is 6 wt%.

[0075] The conductive agent comprises conductive carbon black and conventional graphite in a mass ratio of 1:1; the conductive agent has a mass content of 64 wt% based on 100% of the total solid mass of the aqueous carbon coating slurry; the water-based binder is PAA; the water-based binder has a mass content of 30% based on 100% of the total solid mass of the aqueous carbon coating slurry; the pH of the aqueous carbon coating slurry is 7, and the pH adjuster is sodium hydroxide; the mass ratio of water-based binder, conductive agent, and functional additives in the solid components of the aqueous carbon coating slurry is 30:64:6; the wetting agent is isopropanol; the amount of wetting agent added is 10% of the total mass of the aqueous carbon coating slurry; and the solid content of the aqueous carbon coating slurry is 18 wt%.

[0076] This embodiment also provides a method for preparing the above-mentioned water-based carbon coating slurry, the preparation method comprising the following steps: (1) Preparation of adhesive diluent: In a 200L double star mixing tank, PAA adhesive solution with a viscosity of 1900mPa·s and a solid content of 20wt% is mixed with deionized water and dispersed at a stirring rate of 1100rpm for 30min to obtain an adhesive diluent with a solid content of 15wt% and a viscosity of 850mPa·s.

[0077] (2) Mix the polyetheramine type triethoxysilane with the binder dilution and disperse it at a stirring rate of 2100 rpm for 10 min to obtain the initial slurry.

[0078] The preparation steps of the polyetheramine-type triethoxysilane include: i. Drying the glassware such as the three-necked flask, constant pressure dropping funnel, and condenser, wherein the three-necked flask is equipped with a magnetic stirrer, thermometer, constant pressure dropping funnel, and reflux condenser, and the upper end is connected to an anhydrous calcium chloride drying tube and connected to a nitrogen bag; purging the apparatus with nitrogen gas to create a nitrogen atmosphere; ii. Feeding and reaction: Under nitrogen protection, add measured amounts of polyethylene glycol monomethyl ether and tetrahydrofuran to the dried three-necked flask, and start stirring to completely dissolve the polyethylene glycol monomethyl ether; add measured amounts of isocyanate propyltriethoxysilane to the constant pressure dropping funnel. In a liquid funnel, 1-2 drops of dibutyltin dilaurate catalyst were added to the reaction system. At room temperature (25°C), a solution of propyltriethoxysilane isocyanate was slowly added dropwise, controlling the dropping rate to keep the reaction temperature below 40°C. After the addition was complete, the ice bath was removed. The reaction was continued to be stirred at 45°C for 5 hours. After the reaction was completed, the reaction solution was cooled to room temperature, filtered, and the filtrate was transferred to a round-bottom flask. Rotary evaporation was carried out below 40°C to remove most of the solvent, resulting in a viscous, light yellow, oily liquid. The liquid was then dried at 55°C under high vacuum (<1 mmHg) for 6 hours to obtain the polyetheramine-type triethoxysilane.

[0079] (3) Add a conductive agent with a mass fraction of w1 to the initial slurry and disperse it at a stirring rate of 1600 rpm for 30 min. Then add a conductive agent with a mass fraction of w2 and disperse it at a stirring rate of 2300 rpm for 30 min to obtain an intermediate slurry. Wherein, w1:w2=0.5:0.5 and w1+w2=1. The conductive agent includes conductive carbon black and artificial graphite with a mass ratio of 1:1.

[0080] (4) Add deionized water to the intermediate slurry until the solid content is 12wt%, and disperse it at a stirring rate of 2300rpm for 30min. Then add sodium hydroxide solution to adjust the pH of the slurry system to 7, then add isopropanol, and disperse it at a stirring rate of 13rpm for 40min. After the process, perform two homogenization treatments in a homogenizer at a pressure of 600bar to obtain the water-based carbon coating slurry.

[0081] Example 2 This embodiment provides an aqueous carbon coating slurry for carbon current collectors, which includes a conductive agent, an aqueous binder, a functional additive, a pH adjuster, a wetting agent, and deionized water.

[0082] The functional additive is a ZIF-8 precursor; based on the total solid mass of the aqueous carbon coating slurry as 100%, the mass content of the functional additive is 6 wt%.

[0083] The conductive agent comprises conductive carbon black and conventional graphite in a mass ratio of 1:1; the conductive agent has a mass content of 64 wt% based on 100% of the total solid mass of the aqueous carbon coating slurry; the water-based binder is PAA; the water-based binder has a mass content of 30% based on 100% of the total solid mass of the aqueous carbon coating slurry; the pH of the aqueous carbon coating slurry is 7, and the pH adjuster is sodium hydroxide; the mass ratio of water-based binder, conductive agent, and functional additives in the solid components of the aqueous carbon coating slurry is 30:64:6; the wetting agent is isopropanol; the amount of wetting agent added is 10% of the total mass of the aqueous carbon coating slurry; and the solid content of the aqueous carbon coating slurry is 18 wt%.

[0084] This embodiment also provides a method for preparing the above-mentioned water-based carbon coating slurry, the preparation method comprising the following steps: (1) Preparation of adhesive diluent: In a 200L double star mixing tank, PAA adhesive solution with a viscosity of 1900mPa·s and a solid content of 20wt% is mixed with deionized water and dispersed at a stirring rate of 1100rpm for 30min to obtain an adhesive diluent with a solid content of 15wt% and a viscosity of 850mPa·s.

[0085] (2) Mix the ZIF-8 precursor with the binder dilution and disperse it at a stirring rate of 2100 rpm for 10 min to obtain the initial slurry.

[0086] The preparation steps of the ZIF-8 precursor include: adding zinc nitrate hexahydrate and 2-methylimidazole to deionized water in a molar ratio of 1:6 to obtain the ZIF-8 precursor.

[0087] (3) Add a conductive agent with a mass fraction of w1 to the initial slurry and disperse it at a stirring rate of 1600 rpm for 30 min. Then add a conductive agent with a mass fraction of w2 and disperse it at a stirring rate of 2300 rpm for 30 min to obtain an intermediate slurry. Wherein, w1:w2=0.5:0.5 and w1+w2=1. The conductive agent includes conductive carbon black and artificial graphite with a mass ratio of 1:1.

[0088] (4) Add deionized water to the intermediate slurry until the solid content is 12wt%, and disperse it at a stirring rate of 2300rpm for 30min. Then add sodium hydroxide solution to adjust the pH of the slurry system to 7, then add isopropanol, and disperse it at a stirring rate of 13rpm for 40min. After the process, perform two homogenization treatments in a homogenizer at a pressure of 600bar to obtain the water-based carbon coating slurry.

[0089] Example 3 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 5 wt%, and the mass content of the adaptive conductive agent is 65 wt%.

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] Example 4 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 5 wt%, and the mass content of the adaptive conductive agent is 65 wt%.

[0092] The remaining preparation methods and parameters are consistent with those in Example 2.

[0093] Example 5 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 4 wt%, and the mass content of the adaptive conductive agent is 66 wt%.

[0094] The remaining preparation methods and parameters are consistent with those in Example 1.

[0095] Example 6 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 4 wt%, and the mass content of the adaptive conductive agent is 66 wt%.

[0096] The remaining preparation methods and parameters are consistent with those in Example 2.

[0097] Example 7 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 3 wt%, and the mass content of the adaptive conductive agent is 67 wt%.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Example 8 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 3 wt%, and the mass content of the adaptive conductive agent is 67 wt%.

[0100] The remaining preparation methods and parameters are consistent with those in Example 2.

[0101] Example 9 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 2 wt%, and the mass content of the adaptive conductive agent is 68 wt%.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Example 10 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 2 wt%, and the mass content of the adaptive conductive agent is 68 wt%.

[0104] The remaining preparation methods and parameters are consistent with those in Example 2.

[0105] Example 11 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 1 wt%, and the mass content of the adaptive conductive agent is 69 wt%.

[0106] The remaining preparation methods and parameters are consistent with those in Example 1.

[0107] Example 12 The difference between this embodiment and Embodiment 1 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 7 wt%, and the mass content of the adaptive conductive agent is 63 wt%.

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Example 13 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 1 wt%, and the mass content of the adaptive conductive agent is 69 wt%.

[0110] The remaining preparation methods and parameters are consistent with those in Example 2.

[0111] Example 14 The difference between this embodiment and Embodiment 2 is that, based on the total solid mass of the water-based carbon coating slurry as 100%, the mass content of the functional additive is 7 wt%, and the mass content of the adaptive conductive agent is 63 wt%.

[0112] The remaining preparation methods and parameters are consistent with those in Example 2.

[0113] Example 15 The difference between this embodiment and Embodiment 1 is that the functional additive further includes a ZIF-8 precursor, and the mass ratio of the polyetheramine triethoxysilane to the ZIF-8 precursor is 1:1.

[0114] The remaining preparation methods and parameters are consistent with those in Example 1.

[0115] Comparative Example 1 The difference between this comparative example and Example 1 is that no functional additives are added to the aqueous carbon coating slurry; and the mass content of the conductive agent is 70 wt% based on the total solid mass of the aqueous carbon coating slurry as 100%.

[0116] The remaining preparation methods and parameters are consistent with those in Example 1.

[0117] Comparative Example 2 The difference between this comparative example and Example 1 is that the polyetheramine triethoxysilane is replaced with KH550.

[0118] The remaining preparation methods and parameters are consistent with those in Example 1.

[0119] Comparative Example 3 The difference between this comparative example and Example 2 is that the ZIF-8 precursor is replaced with ZIF-8.

[0120] The remaining preparation methods and parameters are consistent with those in Example 2.

[0121] Performance testing The carbon-coated current collector is prepared based on the water-based carbon coating slurry provided in the above embodiments and comparative examples. The steps include: 1) Selecting an aluminum foil with a width of 300 mm and a thickness of 12 μm as the substrate; 2) Applying the water-based carbon coating slurry evenly to the surface of the aluminum foil using a slot extrusion coating machine, setting the coating line speed to 80 m / min, and precisely controlling the thickness of the wet film coating through the gap of the coating die head; 3) Immediately after coating, the wet film enters a four-section series oven for drying and curing; the temperature of each section of the oven is set as follows: the first section 90℃, the second section 110℃, the third section 100℃, and the fourth section 95℃; 4) After drying, the coated aluminum foil is cooled by a cooling roller and then wound up, and the resulting roll is the finished carbon-coated current collector; in the finished carbon-coated current collector, the single-sided thickness of the carbon coating layer is 1 μm.

[0122] The elongation and tensile strength of the above-mentioned carbon-coated current collector were tested using a Tesmet universal testing machine. The steps included: first, using a template and A4 paper, a 300mm × 180mm sample was cut, and then a 15mm × 150mm strip was prepared using a strip cutter or aluminum foil cutter. The edges of the strip were checked to be smooth and without defects. Next, the universal testing machine and pneumatic clamp were powered on, and the parameters were set in the testing software (according to the equipment parameter table). The strip was placed vertically in the clamp, the pedal was pressed to clamp it, and the value was zeroed before the test was started. After the test was completed, the data was recorded, the clamp was released, the strip was removed, and the test was repeated.

[0123] The test results are shown in Table 1.

[0124] Table 1 analyze: As shown in Table 1, this invention provides an interface-reinforcing slurry with strong process compatibility, capable of significantly improving the tensile strength of carbon-coated current collectors and optimizing their mechanical behavior. During the preparation of the carbon coating layer, the functional additives contained in this slurry can react in situ with impurities on the surface of the current collector substrate to form a high-strength interface-reinforcing layer. This reaction transforms impurities, which were originally mechanical weaknesses, into strengthening points, achieving a "turning waste into treasure" interface-reinforcing effect. This solves the interface-reinforcing problem at the microscopic level and significantly improves the overall rigidity and dimensional stability of the current collector. Therefore, without fundamentally altering the existing water-based carbon coating process, this invention achieves a fundamental enhancement of the mechanical properties of the current collector, effectively improving the processing yield and cycle stability of battery electrodes.

[0125] A comparison of Examples 1, 3, 5, 7, 9, 11 and 12 shows that the less polyetheramine triethoxysilane added, the higher the elongation and the lower the tensile strength of the carbon-coated current collector. If the amount of polyetheramine triethoxysilane added is too low, the interface reinforcement effect will be significantly weakened, and the mechanical properties of the carbon-coated current collector will be close to the level of Comparative Example 1 without functional additives, and it will not be able to effectively inhibit crack initiation and propagation.

[0126] A comparison of Examples 2, 4, 6, 8, 10, 13 and 14 shows that the less ZIF-8 precursor added, the higher the elongation and the lower the tensile strength of the carbon-coated current collector. If the amount of ZIF-8 precursor added is too low, it will be difficult to form a continuous and dense metal-organic framework crystal film in situ on the surface of the current collector, resulting in the loss of the rigid armor reinforcement effect and a significant decrease in the yield strength and dimensional stability of the current collector.

[0127] As can be seen from the comparison between Example 1 and Comparative Example 1, if no functional additives are added to the water-based carbon coating slurry, the tensile strength of the carbon-coated current collector is only 200.6 MPa and the elongation is as high as 3.87%. It is impossible to form an interface reinforcement layer on the surface of the current collector substrate. Impurities, as mechanical weak points, still exist at the interface. The rigidity and dimensional stability of the carbon-coated aluminum foil are both at a low level.

[0128] As can be seen from the comparison between Example 1 and Comparative Example 2, if the polyetheramine triethoxysilane is replaced with KH550, that is, a silane derivative without long-chain polyether segments is used, although the silane groups can still form chemical anchors with impurities on the surface of the current collector, the lack of long-chain polyether segments to form a dense hydrogen bond network with the water-based binder makes it impossible to construct a microscopic viscoelastic buffer layer. Under the action of external forces, it cannot effectively dissipate energy and disperse stress, so the interface enhancement effect is far inferior to that of the present invention.

[0129] As can be seen from the comparison between Example 2 and Comparative Example 3, if the ZIF-8 precursor is replaced with ZIF-8, the pre-synthesized ZIF-8 crystal cannot undergo in-situ coordination self-assembly reaction on the surface of the current collector during the coating and drying process, and cannot form a continuous and dense "ceramic armor" layer that is tightly bonded to the substrate. The reinforcing phase cannot tightly wrap and bridge brittle impurity particles, and the interfacial load-bearing capacity is greatly reduced.

[0130] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A water-based carbon coating slurry for carbon-coated current collectors, characterized in that, The water-based carbon coating slurry includes a conductive agent, a water-based binder, functional additives, a pH adjuster, and a solvent. The functional additives include silane derivatives having long-chain polyether segments and / or metal-organic framework crystal precursor compositions formed by zinc salts and imidazole ligands.

2. The carbon coating slurry for a water-based current collector as described in claim 1, characterized in that, In the silane derivative having long-chain polyether segments, the long-chain polyether segments include any one or a combination of at least two of polyethylene glycol segments, polypropylene glycol segments, or polytetrahydrofuran; And / or, the silane derivative having a long-chain polyether segment includes any one or a combination of at least two of polyetheramine triethoxysilane, polyetheramine trimethoxysilane, or polyethertriethoxysilane; And / or, the metal-organic framework crystal precursor composition includes any one or a combination of at least two of the ZIF-8 precursor, ZIF-67 precursor, or ZIF-11 precursor.

3. The carbon coating slurry for a water-based current collector according to claim 1 or 2, characterized in that, Based on the total solids mass of the water-based carbon coating slurry being 100%, the mass content of the functional additive is 2-6 wt%. And / or, the functional additive is a combination of the silane derivative and the metal-organic framework crystal precursor composition, wherein the mass ratio of the silane derivative to the metal-organic framework crystal precursor composition is (0.5-2):

1.

4. The carbon-coated manifold water-based carbon-coated slurry according to any one of claims 1-3, characterized in that, The conductive agent includes conductive carbon black and / or graphite; And / or, the waterborne adhesive comprises any one or a combination of at least two of waterborne polyacrylic acid, waterborne polyurethane, or waterborne styrene-butadiene rubber; And / or, based on the total solids mass of the water-based carbon coating slurry as 100%, the mass content of the conductive agent is 50-70 wt%; And / or, based on the total solids mass of the water-based carbon coating slurry as 100%, the mass content of the water-based binder is 30-50%; And / or, the pH of the aqueous carbon coating slurry is 6-8; And / or, in the solid components of the water-based carbon coating slurry, the mass ratio of water-based binder, conductive agent and functional additive is (30-47):(50-67):(2-6); And / or, the water-based carbon coating slurry also includes a wetting agent; And / or, the solid content of the water-based carbon coating slurry is 10-25 wt%.

5. A method for preparing a water-based carbon coating slurry for carbon-coated current collectors as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: A conductive agent, an aqueous binder, a functional additive, a pH adjuster, and a solvent are mixed to obtain the water-based carbon coating slurry for carbon coating current collectors; wherein the functional additive includes a composition of a metal-organic framework crystal precursor formed by a silane derivative having a long-chain polyether segment and / or a zinc salt and an imidazole ligand.

6. The preparation method according to claim 5, characterized in that, A wetting agent is also added during the mixing process; And / or, the mixing method includes: (a) The functional additives, water-based adhesive liquid and solvent are mixed to obtain the initial mixture; (b) The conductive agent is added to the initial slurry in batches and mixed, and then the pH adjuster is added and mixed. And / or, the preparation steps of the silane derivative having a long-chain polyether segment include: In an inert atmosphere, a long-chain polyether alcohol and an organic solvent are mixed, and then a silane coupling agent containing isocyanate groups and a catalyst are added to carry out a grafting reaction to obtain the silane derivative having long-chain polyether segments.

7. The preparation method according to claim 6, characterized in that, The solid content of the water-based adhesive solution is 15-25 wt%. And / or, the viscosity of the aqueous adhesive solution is 800-3000 mPa·s; And / or, the conductive agent is added to the initial mixed slurry in two batches, and the mass ratio of the first batch to the second batch is (0.4-0.6):(0.4-0.6); Or, the mixing process in step (a) is accompanied by stirring at a speed of 2000-2200 rpm; And / or, during the process of adding the conductive agent to the initial slurry in batches in step (b), stirring is carried out, and the stirring rate increases gradually with the batches of material added.

8. The preparation method according to any one of claims 5-7, characterized in that, The preparation method includes the following steps: (1) Mix water-based adhesive solution with a viscosity of 800-3000 mPa·s and a solid content of 15-25 wt% with water, and disperse at a stirring rate of 1000-1200 rpm for 20-40 min to obtain an adhesive dilution solution with a solid content of 12-20 wt% and a viscosity of 500-2000 mPa·s; (2) Mix the functional additive with the binder dilution and disperse it at a stirring rate of 2000-2200 rpm for 5-15 min to obtain the initial slurry; The functional additives include silane derivatives with long-chain polyether segments and / or metal-organic framework crystal precursor compositions formed by zinc salts and imidazole ligands. The preparation steps of the silane derivatives with long-chain polyether segments include: mixing long-chain polyether alcohols and organic solvents in an inert atmosphere, then adding silane coupling agents and catalysts containing isocyanate groups, and carrying out a grafting reaction at 40-50°C to obtain the silane derivatives with long-chain polyether segments. (3) Add a conductive agent with a mass fraction of w1 to the initial slurry and disperse it at a stirring rate of 1500-1800 rpm for 20-40 min. Then add a conductive agent with a mass fraction of w2 and disperse it at a stirring rate of 2000-2600 rpm for 20-40 min to obtain an intermediate slurry. Wherein, w1:w2=(0.4-0.6):(0.4-0.6), and w1+w2=1. The conductive agent includes conductive carbon black and graphite with a mass ratio of (1-2):

1. (4) Add water to the intermediate slurry until the solid content is 10-20wt%, and disperse it at a stirring rate of 2000-2600rpm for 20-40min. Then add a pH adjuster to adjust the pH of the slurry system to 6-8, then add a wetting agent, and disperse it at a stirring rate of 10-15rpm for 30-45min. After that, perform homogenization treatment to obtain the carbon coating current collector water system carbon coating slurry.

9. A carbon-coated current collector, characterized in that, The carbon-coated current collector includes a substrate and a carbon coating layer disposed on at least one surface of the substrate, wherein the carbon coating layer is prepared using the water-based carbon coating slurry as described in any one of claims 1-4.

10. A lithium-ion battery, characterized in that, The positive electrode of the lithium-ion battery includes the carbon-coated current collector as described in claim 9.

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