Carbon-coated current collector, preparation method of lithium-supplementing coating material and carbon-coated current collector

Abstract

The invention provides a carbon-coated current collector, a preparation method of a lithium-supplementing coating material and the carbon-coated current collector. The carbon-coated current collector comprises a current collector and the lithium-supplementing coating material coated on the surface of the current collector, the lithium-supplementing coating material comprises an inner core material layer, a middle-layer slow-release layer coating the inner core material layer, and a shell conductive layer coating the middle-layer slow-release layer, wherein the core material layer comprises a lithium supplement additive and a molten electrolyte. According to the scheme, the cycle life of the lithium ion battery can be prolonged.

Description

Technical Field

[0001] The present invention relates to the field of lithium ions, and in particular to a carbon-coated current collector, a preparation method of a lithium-supplementing coating material, and a carbon-coated current collector. Background Art

[0002] At present, the improvement of lithium battery cycle life is mainly achieved by: selecting positive and negative active materials with better structural stability, or improving the coating to slow down the structural changes in the long cycle state. However, due to the increasing mileage requirements and high energy density of batteries, the material structure is more active, and there are certain limitations to improving the cycle life by selecting suitable positive and negative materials;

[0003] Improve the electrolyte retention capacity inside the battery and extend the cycle life. However, the internal space of the battery is currently restricted by the energy density design, and the electrolyte retention space is limited. There is no room for improvement in the electrolyte retention capacity of the diaphragm, electrode materials and internal gaps.

[0004] Control the charge and discharge depth, charge and discharge rate, ambient temperature and battery temperature at the user end to prevent overcharging and over-discharging. However, currently controlling the cycle life of the battery from the user end does not increase the actual cycle life. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a carbon-coated current collector, a preparation method of a lithium-supplementing coating material and a carbon-coated current collector, so as to solve the problem of short cycle life of lithium batteries in the prior art.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A carbon-coated current collector, comprising: a current collector and a lithium-supplementing coating material coated on the surface of the current collector;

[0008] The lithium-supplemented coating material comprises a core material layer, a middle layer sustained-release layer covering the core material layer, and a shell conductive layer covering the middle layer sustained-release layer;

[0009] Among them, the core material layer contains lithium supplement additives and molten electrolyte.

[0010] Optionally, the material of the middle sustained-release layer is a sustained-release coating material, and the material of the outer shell conductive layer is a conductive material.

[0011] Optionally, the lithium replenishing additive is selected from at least one of a lithium-rich compound and a composite organic lithium replenishing agent, and the molten electrolyte includes a molten salt and a molten metal.

[0012] Optionally, the lithium-rich compound includes lithium-rich oxide, lithium nickel oxide, and lithium ferrite.

[0013] Optionally, the molten salt includes a melt of alkali metal, alkaline earth metal halide, nitrate, sulfate, and the molten metal includes molten iron, molten steel and liquid slag.

[0014] Optionally, the sustained-release coating material includes one of polyvinyl alcohol, polylactic acid, and polymethyl methacrylate; the conductive material includes one of carbon black, graphite, CNT, and graphene.

[0015] The present invention also provides a method for preparing a carbon-coated current collector, comprising:

[0016] The molten electrolyte is melted into liquid, and then a lithium supplement additive is added, ultrasonically dispersed, and cooled to obtain a core material layer;

[0017] Coating the inner core material layer with a sustained-release coating material to obtain a middle-layer sustained-release layer coating the inner core material layer;

[0018] Spraying the conductive material onto the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer covering the middle sustained-release layer;

[0019] Drying and solidifying the outer shell conductive layer covering the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material;

[0020] The lithium-supplementing coating material, a binder and a solvent are mixed and dispersed at high speed to prepare a slurry, which is then coated on the surface of a current collector to prepare a carbon-coated current collector.

[0021] Optionally, in terms of mass ratio, the molten electrolyte: lithium replenishing additive is 65:(20-50), and the lithium replenishing coating material: binder: solvent is (20-10):10:(60-80).

[0022] Optionally, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65:35; the lithium replenishing coating material: binder: solvent = 15:10:75.

[0023] The present invention also provides a method for preparing a lithium-supplemented coating material, comprising:

[0024] The molten electrolyte is melted into liquid, and then a lithium supplement additive is added, ultrasonically dispersed, and cooled to obtain a core material layer;

[0025] Coating the inner core material layer with a sustained-release coating material to obtain a middle-layer sustained-release layer coating the inner core material layer;

[0026] Spraying the conductive material onto the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer covering the middle sustained-release layer;

[0027] The outer shell conductive layer covering the middle sustained-release layer is dried and solidified, and then ground to obtain a lithium-supplementing coating material.

[0028] The above solution of the present invention includes at least the following beneficial effects:

[0029] The present invention adopts a method of coating the lithium replenishing coating material with a slow-release coating material and then embedding the material into the outer conductive layer of the conductive porous structure. When the lithium battery is in use, after being infiltrated by the electrolyte inside the battery system, the slow-release material layer slowly dissolves. As the number of cycles increases, the internal lithium replenishing functional material is released, and the lithium source is released to the outer electrode through the conductive porous structure. The process is slow, the lithium source can be continuously replenished, and the cycle life of the lithium battery can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the lithium-supplemented coating material of the present invention.

[0031] 1. Core material layer; 2. Middle sustained-release layer; 3. Outer shell conductive layer. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0033] like Figure 1 As shown, an embodiment of the present invention proposes a carbon-coated current collector, comprising: a current collector and a lithium-replenishing coating material coated on the surface of the current collector; the lithium-replenishing coating material comprises a core material layer, a middle layer sustained-release layer covering the core material layer, and an outer shell conductive layer covering the middle layer sustained-release layer; wherein the core material layer contains a lithium-replenishing additive and a molten electrolyte.

[0034] The lithium-replenishing coating material in this embodiment is a three-layer structure. The outer shell conductive layer ensures the function of the conductive structure and serves as a frame structure. The middle layer sustained-release layer material is a sustained-release material. As it is infiltrated with the electrode liquid, the lithium-replenishing material is slowly released, and the lithium source can be slowly and continuously replenished. The inner core material layer contains a lithium-replenishing additive and a molten electrolyte, which not only provides carbon coating conductivity, but also replenishes the consumption of lithium sources in the long cycle of the lithium battery and improves the cycle life. Among them, the lithium-replenishing additive can continuously provide a lithium source for the battery and improve the cycle life of the battery. The molten electrolyte can replenish the consumption of the electrolyte during the cycle of the lithium battery, thereby improving the cycle life of the battery.

[0035] In an optional implementation manner, the material of the middle sustained-release layer is a sustained-release coating material, and the material of the outer shell conductive layer is a conductive material.

[0036] In this embodiment, the lithium supplement additive is coated with a slow-release coating material and then embedded in the outer shell conductive layer, that is, embedded in the conductive carbon black ball. The outer shell conductive layer is a conductive porous structure. When the lithium battery is in use, after being infiltrated by the electrolyte inside the battery system, the middle slow-release layer slowly dissolves. As the number of cycles increases, the lithium supplement additive in the inner core material layer is released, and the lithium source is released to the outer electrode through the conductive porous structure of the outer shell conductive layer. The process is slow, and the lithium source can be continuously replenished, thereby extending the cycle life of the lithium battery.

[0037] In an optional implementation manner, the lithium supplement additive is selected from lithium-rich compounds, the composite organic lithium supplement agent is a combination of multiple lithium-rich compounds or a composite of multiple lithium-rich compounds, and the molten electrolyte includes molten salt and molten metal.

[0038] In an optional implementation manner, the lithium-rich compound includes lithium-rich oxide, lithium nickel oxide, and lithium ferrite.

[0039] In this embodiment, the core material has a molten electrolyte, which can replenish the consumption of electrolyte during the cycle of the lithium battery, thereby increasing the cycle life of the battery.

[0040] In this embodiment, the molten salt is a molten body composed of metal cations and non-metal anions, such as a molten body of alkali metals, nitrates, and sulfates. The molten metal refers to molten iron, molten steel, and liquid slag.

[0041] In an optional embodiment, the molten salt includes a melt of alkali metal, alkaline earth metal halide, nitrate, sulfate, and the molten metal includes molten iron, molten steel and liquid slag.

[0042] In an optional implementation manner, the sustained-release coating material includes one of polyvinyl alcohol, polylactic acid, and polymethyl methacrylate; and the conductive material includes one of carbon black, graphite, CNT (carbon nanotube), and graphene.

[0043] In this embodiment, the sustained-release coating material is selected from at least one of polyvinyl alcohol (PVA), polylactic acid (PLA), polymethyl methacrylate (PMMA) or liposome.

[0044] The present invention also provides a method for preparing a carbon-coated current collector, comprising:

[0045] The molten electrolyte is melted into a liquid, and then a lithium supplement additive is added, ultrasonically dispersed, and cooled to obtain a core material layer; the core material layer is coated with a slow-release coating material to obtain a middle slow-release layer coating the core material layer; a conductive material is sprayed on the surface of the middle slow-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer coating the middle slow-release layer; the outer shell conductive layer coating the middle slow-release layer is dried and solidified, and a lithium supplement coating material is obtained after grinding; the lithium supplement coating material, a binder, and a solvent are mixed and dispersed at high speed to prepare a slurry, and then coated on the surface of a current collector to prepare a lithium supplement coating carbon-coated current collector.

[0046] In an optional implementation manner, according to the mass ratio, the molten electrolyte: lithium replenishing additive is 65:(20-50), and the lithium replenishing coating material: binder: solvent is (20-10):10:(60-80).

[0047] In this embodiment, the binder is, and the solvent is

[0048] In an optional implementation manner, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65:35; the lithium replenishing coating material: binder: solvent = 15:10:75.

[0049] In this embodiment, the adhesive is any one or more of an acrylic adhesive, a polyacrylate adhesive, a styrene-butadiene emulsion adhesive, a polyvinyl alcohol adhesive, and a polyvinyl acetate adhesive. The solvent is water.

[0050] In this embodiment, the molten electrolyte is melted into a liquid, and then a lithium supplement additive is added, ultrasonic dispersion is performed, and cooling is performed to obtain a core material layer. The specific implementation method is as follows: the molten electrolyte is directly melted into a liquid at a high temperature, and then a lithium supplement additive is added according to a mass ratio of molten electrolyte: lithium supplement additive = 65:35, and then ultrasonic dispersion is performed, and cooling is performed to form a gel core material layer. In this embodiment, the lithium supplement additive is premixed with the molten electrolyte, and the core material layer formed is in a gel state.

[0051] In this embodiment, the sustained-release coating material is used to coat the inner core material layer to obtain the middle sustained-release layer coating the inner core material layer. The specific implementation method is: the sustained-release coating material is used to polymer-coat the gel inner core material layer through a solution impregnation process to obtain the middle sustained-release layer coating the inner core material layer.

[0052] In this embodiment, the conductive material is sprayed on the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain a shell conductive layer covering the middle sustained-release layer. The specific implementation method is as follows: the conductive material layer is sprayed on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure to achieve conductive coating and obtain a shell conductive layer covering the middle sustained-release layer; the shell conductive layer covering the middle sustained-release layer is dried and solidified, and a lithium-supplementing coating material powder is obtained after grinding.

[0053] In this embodiment, the lithium-replenishing coating material, the binder and the solvent are mixed and dispersed at high speed to prepare a slurry, which is then coated on the surface of the current collector to prepare a carbon-coated current collector. The specific implementation method is: the lithium-replenishing coating material powder, the binder and the solvent are dispersed at high speed in a ratio of 15:10:75 to prepare a slurry, which is then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector.

[0054] An optional implementation is to prepare a lithium battery using the carbon-coated current collector prepared as above.

[0055] A preparation method of a lithium-supplementing coating material comprises: melting a molten electrolyte into a liquid, then adding a lithium-supplementing additive, ultrasonically dispersing, and cooling to obtain a core material layer; coating the core material layer with a slow-release coating material to obtain a middle slow-release layer coating the core material layer; spraying a conductive material on the surface of the middle slow-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer coating the middle slow-release layer; drying and solidifying the outer shell conductive layer coating the middle slow-release layer, and grinding to obtain the lithium-supplementing coating material.

[0056] The following is a specific embodiment of the above method:

[0057] Example 1

[0058] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:35, and then ultrasonic dispersion is performed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0059] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0060] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, realize conductive coating, and obtain a shell conductive layer coating the middle sustained-release layer; drying and solidifying the shell conductive layer coating the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT, graphene, conductive carbon black, graphite, etc., preferably CNT.

[0061] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 15:10:75, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0062] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0063] Example 2

[0064] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:20, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0065] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0066] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0067] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 15:10:75, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0068] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0069] Example 3

[0070] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:50, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0071] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0072] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0073] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 15:10:75, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0074] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0075] Example 4

[0076] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:35, and then ultrasonic dispersion is performed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0077] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0078] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0079] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 20:10:60, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0080] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0081] Example 5

[0082] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:35, and then ultrasonic dispersion is performed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0083] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0084] (3) Spraying the conductive material layer onto the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain an outer shell conductive layer covering the middle sustained-release layer; drying and solidifying the outer shell conductive layer covering the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0085] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 10:10:80, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0086] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0087] Example 6

[0088] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:20, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0089] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0090] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0091] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 20:10:60, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0092] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0093] Example 7

[0094] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:20, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0095] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0096] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0097] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 10:10:80, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0098] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0099] Example 8

[0100] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:50, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0101] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0102] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0103] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 20:10:60, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0104] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0105] Example 9

[0106] (1) The molten electrolyte is directly melted into liquid at high temperature, and then the lithium supplement additive is added according to the mass ratio of molten electrolyte: lithium supplement additive = 65:50, and then ultrasonically dispersed and cooled to form a gel core material layer. The molten electrolyte is potassium sulfate and the lithium supplement additive is lithium nickelate.

[0107] (2) The gel-state core material layer is polymer-coated with a sustained-release coating material by a solution impregnation process to obtain a middle-layer sustained-release layer coating the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0108] (3) Spraying the conductive material layer on the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure, achieve conductive coating, and obtain a shell conductive layer that coats the middle sustained-release layer; drying and solidifying the shell conductive layer that coats the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material powder. The conductive material layer is CNT.

[0109] (4) The lithium-supplemented coating material powder, the binder, and the solvent are prepared into a slurry by high-speed dispersion in a ratio of 10:10:80, and then coated on the surface of the current collector by gravure coating technology to prepare a carbon-coated current collector. The current collector is aluminum foil: 1060-H18 13μm.

[0110] (5) A lithium battery is prepared using the carbon-coated current collector prepared as described above.

[0111] Comparative Example

[0112] Traditional light foil current collector, aluminum foil: 1060-H18 13μm (purchase directly)

[0113]

[0114] The present invention adopts the method of coating the lithium replenishing material with a slow-release material and then embedding it into a conductive carbon black ball with a conductive porous structure. When the lithium battery is in use, after being infiltrated by the electrolyte inside the battery system, the slow-release material layer slowly dissolves. As the number of cycles increases, the internal lithium replenishing functional material is released, and the lithium source is released to the outer electrode through the conductive porous structure. The process is slow, the lithium source can be continuously replenished, and the cycle life of the lithium battery can be extended.

[0115] The lithium-supplement coating material of the present invention adds lithium-supplement functional materials, which not only provides carbon coating conductivity, but also can supplement the consumption of lithium source in the long cycle of lithium batteries and improve the cycle life;

[0116] The material has a three-layer structure. The outer layer ensures the function of the conductive structure and serves as a framework structure. The middle layer is a slow-release material. As it is infiltrated with the electrode liquid, it slowly releases the lithium supplement material, which can slowly and continuously supplement the lithium source.

[0117] The core material contains molten electrolyte, which can replenish the consumption of electrolyte during the lithium battery cycle, thereby increasing the battery cycle life.

[0118] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A carbon-coated current collector, characterized in that: include: A current collector and a lithium-supplementing coating material coated on the surface of the current collector; The lithium-supplemented coating material comprises a core material layer, a middle sustained-release layer covering the core material layer, and a shell conductive layer covering the middle sustained-release layer; Among them, the core material layer contains lithium supplement additives and molten electrolyte.

2. The carbon-coated current collector according to claim 1, characterized in that: The material of the middle sustained-release layer is a sustained-release coating material, and the material of the outer shell conductive layer is a conductive material.

3. The carbon-coated current collector according to claim 1, characterized in that: The lithium supplement additive is selected from at least one of a lithium-rich compound and a composite organic lithium supplement agent, and the molten electrolyte includes a molten salt and a molten metal.

4. The carbon-coated current collector according to claim 3, characterized in that: The lithium-rich compounds include lithium-rich oxides, lithium nickel oxide, and lithium ferrite.

5. The carbon-coated current collector according to claim 3, characterized in that: The molten salt includes a melt of alkali metal, alkaline earth metal halide, nitrate, and sulfate, and the molten metal includes molten iron, molten steel, and liquid slag.

6. The carbon-coated current collector according to claim 2, characterized in that: The sustained-release coating material includes one of polyvinyl alcohol, polylactic acid, and polymethyl methacrylate; the conductive material includes one of carbon black, graphite, CNT, and graphene.

7. A method for preparing a carbon-coated current collector, characterized in that: include: The molten electrolyte is melted into liquid, and then a lithium supplement additive is added, ultrasonically dispersed, and cooled to obtain a core material layer; Coating the inner core material layer with a sustained-release coating material to obtain a middle-layer sustained-release layer coating the inner core material layer; Spraying the conductive material onto the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer covering the middle sustained-release layer; The outer shell conductive layer covering the middle sustained-release layer is dried and solidified, and the lithium-supplementing coating material is obtained after grinding; The lithium-supplementing coating material, a binder and a solvent are mixed and dispersed at high speed to prepare a slurry, which is then coated on the surface of a current collector to prepare a carbon-coated current collector.

8. The method for preparing a carbon-coated current collector according to claim 7, characterized in that: According to the mass ratio, the molten electrolyte: lithium supplement additive is 65: (20-50), and the lithium supplement coating material: binder: solvent is (20-10): 10: (60-80).

9. The method for preparing a carbon-coated current collector according to claim 8, characterized in that: According to the mass ratio, the molten electrolyte: lithium supplement additive = 65:35; the lithium supplement coating material: binder: solvent = 15:10:

75.

10. A method for preparing a lithium-supplementing coating material, characterized in that: include: The molten electrolyte is melted into liquid, and then a lithium supplement additive is added, ultrasonically dispersed, and cooled to obtain a core material layer; Coating the inner core material layer with a sustained-release coating material to obtain a middle-layer sustained-release layer coating the inner core material layer; Spraying the conductive material onto the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain an outer shell conductive layer covering the middle sustained-release layer; The outer shell conductive layer covering the middle sustained-release layer is dried and solidified, and then ground to obtain a lithium-supplementing coating material.

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