Carbon-coated current collector and preparation method therefor, and preparation method for lithium-supplementing coating containing material

Abstract

A carbon-coated current collector and a preparation method therefor, and a preparation method for a lithium-supplementing coating containing material. The carbon-coated current collector comprises: a current collector and a lithium-supplementing coating containing material coated on the surface of the current collector. The lithium-supplementing coating containing material comprises a core material layer (1), a middle-layer slow-release layer (2) covering the core material layer, and a shell conductive layer (3) covering the middle-layer slow-release layer, wherein the core material layer comprises a lithium-supplementing additive and a molten electrolyte.

Description

A carbon-coated current collector and its preparation method, and a preparation method of a lithium-supplementing coating material Technical Field

[0001] The present application 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 electrode 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. Therefore, there are certain limitations to improving the cycle life by selecting suitable positive and negative electrode materials.

[0003] Increasing the electrolyte retention capacity inside the battery can extend the cycle life, but 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] Controlling the depth of charge and discharge, charge and discharge rate, ambient temperature and battery temperature at the user end can 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.

[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] The present application provides a carbon-coated current collector, a preparation method of a lithium-supplementing coating material, and a carbon-coated current collector to solve the problem of short cycle life of lithium batteries in related technologies.

[0008] The technical solution of this application is as follows:

[0009] The present application provides a carbon-coated current collector, which comprises: a current collector and a lithium-supplementing coating material coated on the surface of the current collector;

[0010] The lithium-supplementing 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;

[0011] Wherein, the core material layer contains lithium supplement additives and molten electrolyte.

[0012] 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.

[0013] Optionally, the lithium replenishing additive is selected from at least one of a lithium-rich compound or a composite organic lithium replenishing agent, and the molten electrolyte includes a molten salt and a molten metal.

[0014] Optionally, the lithium-rich compound includes lithium-rich oxide, lithium nickelate and lithium ferrite.

[0015] Optionally, the molten salt includes a melt of halides, nitrates and sulfates of alkali metals and alkaline earth metals, and the molten metal includes molten iron, molten steel and liquid slag.

[0016] Optionally, the sustained-release coating material includes one of polyvinyl alcohol (PVA), polylactic acid (PLA) or polymethyl methacrylate (PMMA); the conductive material includes one of carbon black, graphite, carbon nanotubes (CNT) or graphene.

[0017] The present application also provides a method for preparing a carbon-coated current collector, comprising:

[0018] 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;

[0019] Coating the core material layer with a slow-release coating material to obtain a middle slow-release layer coating the core material layer;

[0020] Spraying a 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;

[0021] Drying and solidifying the outer shell conductive layer covering the middle sustained-release layer, and grinding to obtain a lithium-supplementing coating material; and

[0022] 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.

[0023] Optionally, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65: (20-50); the lithium replenishing coating material: binder: solvent = (20-10): 10: (60-80).

[0024] Optionally, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65:35; the lithium replenishing coating material: binder: solvent = 15:10:75.

[0025] The present application also provides a method for preparing a lithium-supplemented coating material, comprising:

[0026] 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;

[0027] Coating the core material layer with a slow-release coating material to obtain a middle slow-release layer coating the core material layer;

[0028] spraying a conductive material onto the surface of the middle sustained-release layer through a carbon nanotube suspension to obtain an outer conductive layer covering the middle sustained-release layer; and

[0029] 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.

[0030] The above solution of the present application includes at least the following beneficial effects:

[0031] This application adopts the method of coating the lithium-replenishing coating material with a slow-release coating material and embedding it into the outer conductive layer of a conductive porous structure. During the use of the lithium battery, 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 process of releasing the lithium source to the outer electrode through the conductive porous structure is slow, which can continuously replenish the lithium source and extend the cycle life of the lithium battery.

[0032] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic structural diagram of a lithium-supplementing coating material of the present application;

[0034] Among them, 1-core material layer; 2-middle sustained-release layer; 3-outer shell conductive layer. DETAILED DESCRIPTION

[0035] The following describes exemplary embodiments of the present application in more detail with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0036] As shown in Figure 1, an embodiment of the present application proposes a carbon-coated current collector, including a current collector and a lithium-replenishing coating material coated on the surface of the current collector; the lithium-replenishing coating material includes a core material layer, a middle sustained-release layer covering the core material layer, and an outer shell conductive layer covering the middle sustained-release layer; wherein the core material layer contains a lithium-replenishing additive and a molten electrolyte.

[0037] The lithium-replenishing coating material in this embodiment has a three-layer structure. The outer shell conductive layer ensures the function of the conductive structure and serves as a frame structure. The material of the middle layer slow-release layer is a slow-release material. As it is infiltrated by the electrode liquid, it slowly releases the lithium-replenishing material, which can slowly and continuously replenish the lithium source; the inner core material layer contains a lithium-replenishing additive and a molten electrolyte, which not only provides carbon coating conductivity, but also can replenish the consumption of lithium sources in the long cycle of the lithium battery, thereby improving the cycle life; among them, the lithium-replenishing additive can continuously provide lithium sources for the battery, thereby improving the cycle life of the battery, and the molten electrolyte can replenish the consumption of electrolyte during the cycle of the lithium battery, thereby improving the cycle life of the battery.

[0038] In an optional embodiment, 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.

[0039] In this embodiment, the lithium replenishing additive is coated with a slow-release coating material and then embedded in the outer conductive layer, that is, embedded in the conductive carbon black ball. The outer conductive layer is a conductive porous structure. During the use of the lithium battery, 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 replenishing additive in the inner core material layer is released. The process of releasing the lithium source to the outer electrode through the conductive porous structure of the outer conductive layer is slow, which can continuously replenish the lithium source and extend the cycle life of the lithium battery.

[0040] In an optional embodiment, the lithium replenishing additive is selected from lithium-rich compounds, the composite organic lithium replenishing 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.

[0041] In an optional embodiment, the lithium-rich compound includes lithium-rich oxide, lithium nickelate and lithium ferrite.

[0042] In this embodiment, the core material includes 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.

[0043] In this embodiment, the molten salt is a melt composed of metal cations and non-metal anions, such as a melt of alkali metals, nitrates and sulfates. The molten metal refers to molten iron, molten steel and liquid slag.

[0044] In an optional embodiment, the molten salt includes a melt of halides, nitrates and sulfates of alkali metals and alkaline earth metals, and the molten metal includes molten iron, molten steel and liquid slag.

[0045] In an optional embodiment, the sustained-release coating material includes one of polyvinyl alcohol, polylactic acid or polymethyl methacrylate; and the conductive material includes one of carbon black, graphite, CNT or graphene.

[0046] In this embodiment, the sustained-release coating material is selected from at least one of polyvinyl alcohol, polylactic acid, polymethyl methacrylate or liposome.

[0047] The present application also provides a method for preparing a carbon-coated current collector, comprising:

[0048] 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 onto 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 then ground to obtain a lithium-containing coating material; the lithium-containing 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 lithium-containing carbon-coated current collector.

[0049] In an optional embodiment, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65: (20-50), and the lithium replenishing coating material: binder: solvent = (20-10): 10: (60-80).

[0050] In an optional embodiment, according to the mass ratio, the molten electrolyte: lithium replenishing additive = 65:35, and the lithium replenishing coating material: binder: solvent = 15:10:75.

[0051] 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, or a polyvinyl acetate adhesive. The solvent is water.

[0052] In this embodiment, the core material layer is formed by melting the molten electrolyte into a liquid, then adding a lithium-supplementing additive, ultrasonically dispersing the additive, and cooling the electrolyte. The specific embodiment is as follows: the molten electrolyte is directly melted into a liquid at a high temperature, and then the lithium-supplementing additive is added in a mass ratio of molten electrolyte to lithium-supplementing additive of 65:35. The lithium-supplementing additive is then ultrasonically dispersed and cooled to form a gel-like core material layer. In this embodiment, the lithium-supplementing additive and the molten electrolyte are premixed to form a gel-like core material layer.

[0053] In this embodiment, the sustained-release coating material is used to coat the core material layer to obtain the middle sustained-release layer coating the core material layer. The specific implementation method is: the gel-state core material layer is polymer-coated by the sustained-release coating material through a solution impregnation process to obtain the middle sustained-release layer coating the core material layer.

[0054] In this embodiment, the conductive material is sprayed onto 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 onto the surface of the middle sustained-release layer through a carbon nanotube suspension to form a carbon nanotube network structure to achieve conductive coating, thereby obtaining 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 then ground to obtain a lithium-supplementing coating material powder.

[0055] 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 as follows: the lithium-replenishing coating material powder, the binder, and the solvent are dispersed at high speed to prepare a slurry 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.

[0056] An optional implementation is to prepare a lithium battery using the carbon-coated current collector prepared above.

[0057] The present application also provides a method for preparing a lithium-supplementing coating material, comprising: 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 onto 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 curing the outer shell conductive layer coating the middle slow-release layer, and grinding to obtain the lithium-supplementing coating material.

[0058] The following are specific embodiments of the above method:

[0059] Example 1

[0060] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:35. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0061] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0062] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure and achieve conductive coating, thereby obtaining 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-containing coating material powder. The conductive material layer is CNT, graphene, conductive carbon black, or graphite, preferably CNT.

[0063] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion in a ratio of 15:10:75. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0064] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0065] Example 2

[0066] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:20. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0067] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0068] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0069] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion in a ratio of 15:10:75. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0070] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0071] Example 3

[0072] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:50. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0073] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0074] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0075] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion in a ratio of 15:10:75. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0076] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0077] Example 4

[0078] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:35. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0079] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0080] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0081] (4) The lithium-replenishing coating material powder, binder, and solvent were prepared into a slurry by high-speed dispersion in a ratio of 20:10:60. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13μm.

[0082] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0083] Example 5

[0084] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:35. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0085] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0086] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0087] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion at a ratio of 10:10:80. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0088] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0089] Example 6

[0090] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:20. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0091] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0092] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0093] (4) The lithium-replenishing coating material powder, binder, and solvent were prepared into a slurry by high-speed dispersion in a ratio of 20:10:60. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13μm.

[0094] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0095] Example 7

[0096] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:20. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0097] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0098] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0099] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion at a ratio of 10:10:80. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0100] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0101] Example 8

[0102] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:50. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0103] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0104] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0105] (4) The lithium-replenishing coating material powder, binder, and solvent were prepared into a slurry by high-speed dispersion in a ratio of 20:10:60. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13μm.

[0106] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0107] Example 9

[0108] (1) The molten electrolyte is directly melted into a liquid at high temperature. A lithium supplement is then added at a mass ratio of molten electrolyte to lithium supplement of 65:50. The mixture is then ultrasonically dispersed and cooled to form a gel-like core material layer. The molten electrolyte is potassium sulfate, and the lithium supplement is lithium nickelate.

[0109] (2) The gel-like core material layer is polymer-coated with a sustained-release coating material through a solution impregnation process to obtain a middle sustained-release layer covering the core material layer. The sustained-release coating material is polyvinyl alcohol.

[0110] (3) spraying a conductive material layer onto the surface of the middle sustained-release layer using a carbon nanotube suspension to form a carbon nanotube network structure, thereby achieving conductive coating and obtaining 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 the outer shell conductive layer to obtain a lithium-containing coating material powder. The conductive material layer is CNT.

[0111] (4) A lithium-replenishing coating material powder, a binder, and a solvent were prepared into a slurry by high-speed dispersion at a ratio of 10:10:80. The slurry was then coated onto the surface of the current collector by gravure coating to prepare a carbon-coated current collector. The current collector was aluminum foil: 1060-H18 13 μm.

[0112] (5) A lithium battery is prepared using the carbon-coated current collector prepared above.

[0113] Comparative Example

[0114] Traditional light foil current collector, aluminum foil: 1060-H18 13μm (purchase directly).

[0115] This application uses a slow-release material to coat the lithium-replenishing material and then embeds it into the conductive carbon black balls with a conductive porous structure. During the use of the lithium battery, 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. The process of releasing the lithium source to the outer electrode through the conductive porous structure is slow, which can continuously replenish the lithium source and extend the cycle life of the lithium battery.

[0116] The lithium-replenishing coating material of this application adds lithium-replenishing functional materials, which not only provides carbon coating conductivity, but also replenishes the consumption of lithium source in the long cycle of lithium batteries and improves the cycle life;

[0117] The material has a three-layer structure. The outer layer ensures the function of the conductive structure and acts 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 replenishing material, which can slowly and continuously replenish the lithium source.

[0118] The core material contains molten electrolyte, which can replenish the consumption of electrolyte during the lithium battery cycle, thereby improving the battery cycle life.

[0119] The above is a preferred embodiment of the present application. 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 described in the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A carbon-coated current collector, comprising 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 layer slow-release layer covering the core material layer, and a shell conductive layer covering the middle layer slow-release layer; in, The core material layer includes a lithium supplement additive and a molten electrolyte.

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

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

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

5. The carbon-coated current collector according to claim 3, wherein: The molten salt includes a melt of halides, nitrates and sulfates of alkali metals and alkaline earth metals; the molten metal includes molten iron, molten steel and liquid slag.

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

7. A method for preparing a carbon-coated current collector, comprising: 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; as well as The lithium-supplementing 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.

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

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

75.

10. A method for preparing a lithium-supplementing coating material, comprising: 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; as well as 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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