Current collector NANO safety coating and preparation method therefor

Abstract

A current collector nano safety coating and a preparation method therefor. The preparation method comprises: uniformly mixing a temperature-sensitive polymer material and a binder A, then adding a conductive agent for dispersion and coating, and sequentially carrying out first drying and refining to obtain a coated material; uniformly mixing a binder B, a solvent, and the obtained coated material; and coating the surface of a current collector with an obtained nano safety coating slurry, and carrying out second drying to obtain the current collector nano safety coating. In the preparation method, the outside of the temperature-sensitive polymer material is coated with the conductive agent to obtain the coated material. On the one hand, the resistance of the temperature-sensitive polymer material can be increased along with the rise of the temperature, thereby achieving the purpose of inhibiting a reaction; and on the other hand, the contact of the outside conductive agent is good, so that good conductivity can be ensured. Moreover, the preparation method is simple and easily implemented, has no special requirements on a device, has low costs and high efficiency, and facilitates large-scale production.

Description

A current collector nano safety coating and preparation method thereof Technical Field

[0001] The embodiments of the present application relate to the field of lithium-ion battery technology, for example, a current collector nano-safety coating and a preparation method thereof. Background Art

[0002] Lithium-ion batteries have been widely used in consumer electronics, electric vehicles, and other fields. The market has also placed higher demands on their energy density, cycle life, and safety. As the energy density of lithium-ion batteries continues to increase, the safety issues they face are becoming increasingly severe. A major safety issue is thermal runaway. Abnormal reactions within the battery generate excessive heat, leading to fire or even explosion.

[0003] To improve this problem, the current collector safety primer technology can effectively block the occurrence of various abnormal reactions and improve the safety characteristics of the battery. At the same time, it can reduce the contact resistance between the electrode material and the current collector, increase the adhesion between the electrode material and the current collector, reduce the internal resistance of the battery, and extend the battery life. For example, the prior art discloses a positive electrode plate and a lithium-ion battery containing a high-safety thermosensitive coating. The thermosensitive coating includes a first conductive agent, a first binder, thermosensitive polymer microspheres, and an additive. The thermosensitive coating has conductive properties at room temperature and has the advantages of increasing the contact area between the active material and the current collector, improving the conductivity, and effectively reducing the polarization of the battery. When the operating temperature of the positive electrode plate reaches 120°C or above, the thermosensitive polymer microspheres will melt to form multiple continuous electron blocking layers. The coating forms a current blockage, forming an internal blockage inside the battery to prevent further thermal runaway of the lithium-ion battery.

[0004] However, the current current collector safety primer technology still has shortcomings, and it is necessary to develop a new type of current collector nano-safety coating and its preparation method.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] In view of the problems existing in the prior art, the embodiments of the present application provide a current collector nano safety coating and a preparation method thereof, the preparation method comprising: after uniformly mixing a temperature-sensitive polymer material and a binder A, adding a conductive agent for dispersion and coating, sequentially undergoing a first drying and refinement to obtain a coated material; uniformly mixing a binder B, a solvent and the obtained coated material; coating the obtained nano safety coating slurry on the surface of the current collector, and obtaining a current collector nano safety coating through a second drying. The preparation method described in the present application coats the conductive agent on the outside of the temperature-sensitive polymer material to obtain the coated material. On the one hand, the resistance of the temperature-sensitive polymer material can increase with increasing temperature, thereby achieving the purpose of inhibiting the reaction. On the other hand, the conductive agents on the outside have good contact with each other, which can ensure good conductive performance. Moreover, the preparation method described in the present application is simple and easy to implement, has no special requirements for equipment, is low in cost, highly efficient, and easy to implement on a large scale.

[0008] In a first aspect, an embodiment of the present application provides a method for preparing a current collector nano-safety coating, the preparation method comprising the following steps:

[0009] (1) After the temperature-sensitive polymer material and the binder A are uniformly mixed, a conductive agent is added for dispersion and coating, and the mixture is dried and refined in sequence to obtain a coated material;

[0010] (2) uniformly mixing the binder B, the solvent and the coating material obtained in step (1) to obtain a nano safety coating slurry;

[0011] (3) Applying the nano safety coating slurry described in step (2) on the surface of the current collector, and obtaining the current collector nano safety coating through a second drying process.

[0012] The preparation method described in the present application is to coat the conductive agent on the outside of the temperature-sensitive polymer material to obtain a coated material. On the one hand, the resistance of the temperature-sensitive polymer material can increase with the increase of temperature, thereby achieving the purpose of inhibiting the reaction. On the other hand, the conductive agents on the outside are in good contact with each other, which can ensure good conductive performance. Moreover, the preparation method described in the present application is simple and easy, has no special requirements for equipment, is low in cost, high in efficiency, and can be easily implemented on a large scale.

[0013] It is worth noting that the preparation method described in the present application requires first using binder A to combine the conductive agent with the temperature-sensitive polymer material to form a coating material, and then using binder B to adhere the coating material to the surface of the current collector to obtain the current collector nano safety coating; moreover, the binder A and binder B described in the present application have opposite solubility in the solvent, for example, binder A is insoluble in water, and binder B is soluble in water or dispersed in water, so as to avoid the coating material from dissolving during the process of mixing evenly to obtain the nano safety coating slurry in step (2), and to avoid the conductive agent from falling off.

[0014] As a preferred technical solution of the present application, the temperature-sensitive polymer material in step (1) includes any one of polyethylene, polyvinyl alcohol or poly-ε-caprolactone, or a combination of at least two of them. Typical but non-limiting examples of the combination include: a combination of polyethylene and polyvinyl alcohol, a combination of polyvinyl alcohol and poly-ε-caprolactone, or a combination of polyethylene and poly-ε-caprolactone, etc.

[0015] It is worth noting that the temperature-sensitive polymer material described in this application is a large molecular weight temperature-sensitive polymer material with a microcrystalline structure, which can enable the current collector nano-safety coating to maintain a low resistance under normal temperature conditions. As the temperature rises, the resistance of the nano-safety coating also increases, achieving the purpose of inhibiting the reaction; the reason for the increase in resistance is that the microcrystalline structure of the temperature-sensitive polymer material can hinder the movement of electrons, thereby generating a higher resistance.

[0016] Preferably, the molecular weight of the temperature-sensitive polymer material in step (1) is 50,000-200,000, for example, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000 or 200,000, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0017] Preferably, the particle size of the thermosensitive polymer material in step (1) is 1-3 μm, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0018] As a preferred technical solution of the present application, the binder A in step (1) includes any one or a combination of at least two of polyurethane resin and its derivatives.

[0019] Preferably, the uniform mixing in step (1) further comprises adding a first solvent for mixing.

[0020] Preferably, the first solvent comprises toluene.

[0021] It is worth noting that the first solvent in the present application only serves to accelerate mixing. It will not react chemically with other materials and is volatile and can be removed in the subsequent first drying. Therefore, there is no excessive restriction on the amount of the first solvent used, and those skilled in the art can make a reasonable choice based on actual conditions.

[0022] As a preferred technical solution of the present application, the conductive agent in step (1) includes any one or a combination of at least two of conductive carbon black, conductive graphite or carbon nanotubes. Typical but non-limiting examples of the combination are: a combination of conductive carbon black and conductive graphite, a combination of conductive graphite and carbon nanotubes, or a combination of conductive carbon black and carbon nanotubes, etc.

[0023] Preferably, the particle size of the conductive agent in step (1) is 0.2-0.8 μm, such as 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm or 0.8 μm, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0024] As a preferred technical solution of the present application, the mass ratio of the temperature-sensitive polymer material and the binder A in step (1) is (10-50):1, for example, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0025] Preferably, the mass ratio of the temperature-sensitive polymer material and the conductive agent in step (1) is (0.5-2):1, for example, 0.5:1, 0.6:1, 0.8:1, 1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1 or 2:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0026] As a preferred technical solution of the present application, the first drying in step (1) includes oven drying.

[0027] Preferably, the refining in step (1) comprises grinding.

[0028] As a preferred technical solution of the present application, in step (2), the mass ratio of the coating material obtained in step (1) to the binder B is (0.5-2):1, for example, 0.5:1, 0.6:1, 0.8:1, 1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1 or 2:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0029] Preferably, in step (2), the binder B comprises any one or a combination of at least two of polyacrylic acid resin and its derivatives.

[0030] Preferably, the solvent in step (2) comprises water.

[0031] Preferably, the mass ratio of the solvent to the coating material in step (2) is (10-40):1, for example, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1 or 40:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] Preferably, the uniform mixing in step (2) includes sand grinding dispersion.

[0033] As a preferred technical solution of the present application, the coating in step (3) is carried out using a coating machine.

[0034] Preferably, the current collector in step (3) is an aluminum current collector.

[0035] Preferably, the second drying in step (3) includes oven drying.

[0036] Preferably, the temperature of the second drying in step (3) is 80-120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0037] Preferably, the thickness of the current collector nano-safety coating in step (3) is 1-10 μm, for example, 1 μm, 3 μm, 5 μm, 6 μm, 8 μm or 10 μm, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0038] As a preferred technical solution of this application, the preparation method comprises the following steps:

[0039] (1) After the temperature-sensitive polymer material and the binder A are uniformly mixed, a conductive agent is added for dispersion and coating, and then the mixture is dried and ground to obtain a coated material;

[0040] The thermosensitive polymer material comprises any one or a combination of at least two of polyethylene, polyvinyl alcohol or poly-ε-caprolactone; the molecular weight of the thermosensitive polymer material is 50,000-200,000; the particle size of the thermosensitive polymer material is 1-3 μm; the binder A comprises any one or a combination of at least two of polyurethane resin and its derivatives; the conductive agent comprises any one or a combination of at least two of conductive carbon black, conductive graphite or carbon nanotubes; the particle size of the conductive agent is 0.2-0.8 μm; the mass ratio of the thermosensitive polymer material to the binder A is (10-50):1; the mass ratio of the thermosensitive polymer material to the conductive agent is (0.5-2):1;

[0041] (2) uniformly mixing the binder B, the solvent and the coating material obtained in step (1) to obtain a nano safety coating slurry;

[0042] The mass ratio of the obtained coating material to the binder B is (0.5-2):1; the binder B comprises any one or a combination of at least two of polyacrylic acid resin and its derivatives; the solvent comprises water; the mass ratio of the solvent to the coating material is (10-40):1; and the uniform mixing comprises sand grinding and dispersion;

[0043] (3) applying the nano safety coating slurry of step (2) on the surface of the current collector using a coating machine, and obtaining the current collector nano safety coating through a second drying process;

[0044] Wherein, the second drying includes baking; the temperature of the second drying is 80-120° C.; and the thickness of the current collector nano safety coating is 1-10 μm.

[0045] In a second aspect, an embodiment of the present application provides a current collector nano-safety coating obtained according to the preparation method described in the first aspect.

[0046] Compared with the related technical solutions, the embodiments of the present application have at least the following beneficial effects:

[0047] (1) The preparation method described in the embodiment of the present application coats the conductive agent on the outside of the temperature-sensitive polymer material to obtain a coated material. On the one hand, the resistance of the temperature-sensitive polymer material can increase with the increase of temperature, thereby achieving the purpose of suppressing the reaction. On the other hand, the conductive agents on the outside are in good contact with each other, which can ensure good conductive performance.

[0048] (2) The preparation method described in the examples of the present application is simple and easy to implement, has no special requirements for equipment, is low in cost, high in efficiency, and can be easily implemented on a large scale;

[0049] (3) The thermosensitive polymer material described in the embodiment of the present application is a large molecular weight thermosensitive polymer material with a microcrystalline structure, which can enable the current collector nano-safety coating to maintain a low resistance under normal temperature conditions. As the temperature rises, the resistance of the nano-safety coating also increases, achieving the purpose of inhibiting the reaction; the reason for the increase in resistance is that the microcrystalline structure of the thermosensitive polymer material can hinder the movement of electrons, thereby generating a higher resistance.

[0050] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0051] To facilitate understanding of the present application, the present application lists the following examples. Those skilled in the art should understand that the examples are only provided to help understand the present application and should not be considered as specific limitations of the present application.

[0052] Example 1

[0053] This embodiment provides a method for preparing a current collector nano-safety coating, the preparation method comprising the following steps:

[0054] (1) 10 kg of polyethylene powder with a particle size of 2 μm and 0.5 kg of polyurethane resin are uniformly mixed in a first solvent of toluene, wherein the molecular weight of the polyethylene is 100,000, and then 10 kg of conductive carbon black with a particle size of 0.5 μm is added for dispersion and coating, that is, the mass ratio of the temperature-sensitive polymer material to the binder A is 20:1, and the mass ratio of the temperature-sensitive polymer material to the conductive agent is 1:1. The mixture is dried and ground to obtain a coated material;

[0055] (2) 10 kg of the coating material obtained in step (1), 40 kg of a polyacrylic acid resin aqueous solution (solid content of 25 wt%), and an appropriate amount of water are mixed uniformly to obtain a nano safety coating slurry with a solid content of 10 wt%; wherein the mass ratio of the obtained coating material to the binder B is 1:1; the uniform mixing includes sand grinding and dispersion for 4 hours;

[0056] (3) The nano safety coating slurry described in step (2) is coated on both sides of an aluminum current collector with a thickness of 13 μm using a coating machine, and dried at 100° C. to obtain a current collector nano safety coating with a thickness of 1 μm.

[0057] Example 2

[0058] This embodiment provides a method for preparing a current collector nano-safety coating. Compared with the preparation method described in Example 1, the only difference is that the temperature-sensitive polymer material in step (1) is replaced by polyvinyl alcohol of equal mass.

[0059] Example 3

[0060] This embodiment provides a method for preparing a current collector nano-safety coating. Compared with the preparation method described in Example 1, the only difference is that the temperature-sensitive polymer material in step (1) is replaced by poly-ε-caprolactone of equal mass.

[0061] Example 4

[0062] This embodiment provides a method for preparing a current collector nano-safety coating. Compared with the preparation method described in Example 1, the only difference is that the temperature-sensitive polymer material in step (1) is replaced by PMMA of equal mass.

[0063] Example 5

[0064] This embodiment provides a method for preparing a current collector nano-safety coating, the preparation method comprising the following steps:

[0065] (1) 5 kg of polyethylene powder with a particle size of 1 μm and 0.5 kg of polyurethane resin are uniformly mixed in a first solvent of toluene, wherein the molecular weight of the polyethylene is 50,000, and then 10 kg of conductive carbon black with a particle size of 0.2 μm is added for dispersion and coating, that is, the mass ratio of the temperature-sensitive polymer material to the binder A is 10:1, and the mass ratio of the temperature-sensitive polymer material to the conductive agent is 0.5:1. The mixture is dried and ground to obtain a coated material;

[0066] (2) 5 kg of the coating material obtained in step (1), 40 kg of a polyacrylic acid resin aqueous solution (solid content of 25 wt%), and an appropriate amount of water are mixed uniformly to obtain a nano safety coating slurry with a solid content of 10 wt%; wherein the mass ratio of the obtained coating material to the binder B is 0.5:1; the uniform mixing includes sand grinding and dispersion for 4 hours;

[0067] (3) The nano safety coating slurry described in step (2) is coated on both sides of an aluminum current collector with a thickness of 13 μm using a coating machine, and dried at 80° C. to obtain a current collector nano safety coating with a thickness of 1 μm.

[0068] Example 6

[0069] This embodiment provides a method for preparing a current collector nano-safety coating, the preparation method comprising the following steps:

[0070] (1) 25 kg of polyethylene powder with a particle size of 3 μm and 0.5 kg of polyurethane resin are uniformly mixed in a first solvent of toluene, wherein the molecular weight of the polyethylene is 200,000, and then 12.5 kg of conductive carbon black with a particle size of 0.8 μm is added for dispersion and coating, that is, the mass ratio of the temperature-sensitive polymer material to the binder A is 50:1, and the mass ratio of the temperature-sensitive polymer material to the conductive agent is 2:1. The mixture is dried and ground to obtain a coated material;

[0071] (2) 20 kg of the coating material obtained in step (1), 40 kg of a polyacrylic acid resin aqueous solution (solid content of 25 wt%), and an appropriate amount of water are mixed uniformly to obtain a nano safety coating slurry with a solid content of 10 wt%; wherein the mass ratio of the obtained coating material to the binder B is 2:1; the uniform mixing includes sand grinding and dispersion for 4 hours;

[0072] (3) The nano safety coating slurry described in step (2) is coated on both sides of an aluminum current collector with a thickness of 13 μm using a coating machine, and dried at 120° C. to obtain a current collector nano safety coating with a thickness of 1 μm.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a current collector nano-safety coating, the preparation method comprising the following steps:

[0075] (1) 0.5 kg of polyurethane resin and 10 kg of conductive carbon black with a particle size of 0.5 μm were mixed uniformly in a first solvent of toluene, and then dried and ground to obtain a coated material;

[0076] (2) 10 kg of the coating material obtained in step (1), 40 kg of a polyacrylic acid resin aqueous solution (solid content of 25 wt%), and an appropriate amount of water are mixed uniformly to obtain a nano safety coating slurry with a solid content of 10 wt%; wherein the mass ratio of the obtained coating material to the binder B is 1:1; the uniform mixing includes sand grinding and dispersion for 4 hours;

[0077] (3) The nano safety coating slurry of step (2) is coated on both sides of a 13 μm aluminum current collector with a thickness of 1 μm using a coating machine, and dried at 100° C. to obtain a current collector nano safety coating.

[0078] That is to say, compared with the preparation method described in Example 1, the only difference is that the temperature-sensitive polymer material (polyethylene powder) described in step (1) is completely omitted.

[0079] The nano-safety coating of the current collector of the above embodiment and the comparative example, that is, the current collector with the nano-safety coating, was tested for penetration resistance according to the following method. The relevant test results are shown in Table 1.

[0080] Penetration resistance: Tested using a pole piece resistance meter. Cut the current collector with the nano-safety coating to be tested into a square of approximately 5cm×5cm, place it under the test head, maintain the pressure at 0.3t for 5s, and test the penetration resistance at 25℃ and 160℃ respectively.

[0081] Table 1

[0082] To sum up, the preparation method described in the present application coats the conductive agent on the outside of the temperature-sensitive polymer material to obtain a coated material. On the one hand, the resistance of the temperature-sensitive polymer material can increase with the increase of temperature, thereby achieving the purpose of inhibiting the reaction. On the other hand, the conductive agents on the outside are in good contact with each other, which can ensure good conductive performance; the preparation method described in the present application is simple and easy, has no special requirements for equipment, is low in cost, high in efficiency, and easy to implement on a large scale; the temperature-sensitive polymer material described in the present application is a large molecular weight temperature-sensitive polymer material with a microcrystalline structure, which can enable the current collector nano-safety coating to maintain a low resistance under normal temperature conditions. As the temperature rises, the resistance of the nano-safety coating also increases, thereby achieving the purpose of inhibiting the reaction; the reason for the increase in resistance is that the microcrystalline structure of the temperature-sensitive polymer material can hinder the movement of electrons, thereby generating a higher resistance.

[0083] This application uses the above-mentioned embodiments to illustrate the detailed process equipment and process flow of this application. However, this application is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that this application must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent replacement of various raw materials of the product of this application, addition of auxiliary ingredients, selection of specific methods, etc., all fall within the scope of protection and disclosure of this application.

Claims

1. A method for preparing a current collector nano-safety coating, comprising the following steps: (1) After the temperature-sensitive polymer material and the binder A are uniformly mixed, a conductive agent is added for dispersion and coating, and first drying and refining are performed in sequence to obtain a coated material; (2) mixing the binder B, the solvent and the coated material obtained in step (1) to obtain a nano safety coating slurry; (3) Applying the nano safety coating slurry described in step (2) on the surface of the current collector, and obtaining the current collector nano safety coating through a second drying process.

2. The preparation method according to claim 1, wherein The temperature-sensitive polymer material in step (1) includes any one of polyethylene, polyvinyl alcohol or poly-ε-caprolactone, or a combination of at least two of them.

3. The preparation method according to claim 1 or 2, wherein The molecular weight of the temperature-sensitive polymer material in step (1) is 50,000-200,000.

4. The preparation method according to any one of claims 1 to 3, wherein: The particle size of the temperature-sensitive polymer material in step (1) is 1-3 μm.

5. The preparation method according to any one of claims 1 to 4, wherein: The binder A in step (1) comprises any one of polyurethane resin and its derivatives or a combination of at least two thereof.

6. The preparation method according to any one of claims 1 to 5, wherein: The uniform mixing in step (1) further comprises adding a first solvent for mixing; Preferably, the first solvent comprises toluene.

7. The preparation method according to any one of claims 1 to 6, wherein: The conductive agent in step (1) includes any one of conductive carbon black, conductive graphite or carbon nanotubes, or a combination of at least two thereof; Preferably, the particle size of the conductive agent in step (1) is 0.2-0.8 μm.

8. The preparation method according to any one of claims 1 to 7, wherein: The mass ratio of the temperature-sensitive polymer material to the binder A in step (1) is (10-50):1; Preferably, in step (1), the mass ratio of the temperature-sensitive polymer material to the conductive agent is (0.5-2):

1.

9. The preparation method according to any one of claims 1 to 8, wherein: In step (1), the first drying includes drying; Preferably, the refining in step (1) comprises grinding.

10. The preparation method according to any one of claims 1 to 9, wherein: In step (2), the mass ratio of the coating material obtained in step (1) to the binder B is (0.5-2):1; Preferably, in step (2), the binder B comprises any one or a combination of at least two of polyacrylic acid resin and its derivatives; Preferably, the solvent in step (2) comprises water; Preferably, in step (2), the mass ratio of the solvent to the coating material is (10-40):1; Preferably, the uniform mixing in step (2) includes sand grinding dispersion.

11. The preparation method according to any one of claims 1 to 10, wherein: The coating in step (3) is carried out using a coating machine; Preferably, the current collector in step (3) is an aluminum current collector; Preferably, in step (3), the second drying comprises drying; Preferably, the temperature of the second drying in step (3) is 80-120°C; Preferably, the thickness of the current collector nano-safety coating in step (3) is 1-10 μm.

12. The preparation method according to any one of claims 1 to 11, comprising the steps of: (1) After the temperature-sensitive polymer material and the binder A are uniformly mixed, a conductive agent is added for dispersion and coating, and then the mixture is dried and ground to obtain a coated material; in, The temperature-sensitive polymer material includes any one of polyethylene, polyvinyl alcohol or poly-ε-caprolactone or a combination of at least two thereof; the molecular weight of the temperature-sensitive polymer material is 50,000-200,000; The particle size of the temperature-sensitive polymer material is 1-3 μm; the binder A includes any one of polyurethane resin and its derivatives or a combination of at least two thereof; the conductive agent includes any one of conductive carbon black, conductive graphite or carbon nanotubes or a combination of at least two thereof; the particle size of the conductive agent is 0.2-0.8 μm; the mass ratio of the temperature-sensitive polymer material to the binder A is (10-50):1; the mass ratio of the temperature-sensitive polymer material to the conductive agent is (0.5-2):1; (2) mixing the binder B, the solvent and the coated material obtained in step (1) to obtain a nano safety coating slurry; The mass ratio of the obtained coating material to the binder B is (0.5-2):1; the binder B comprises any one or a combination of at least two of polyacrylic acid resin and its derivatives; the solvent comprises water; the mass ratio of the solvent to the coating material is (10-40):1; the mixing comprises sand grinding dispersion; (3) applying the nanometer safety coating slurry in step (2) onto the surface of the current collector by using a coating machine, and obtaining the current collector nanometer safety coating by a second drying; Wherein, the second drying includes baking; the temperature of the second drying is 80-120° C.; and the thickness of the current collector nano-safety coating is 1-10 μm.

13. A current collector nano-safety coating obtained according to the preparation method according to any one of claims 1 to 12.

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