A carbon-coated aluminum current collector suitable for a positive electrode capable of lithium supplement and a preparation method thereof

Abstract

The present application relates to the technical field of current collector preparation, in particular to a carbon-coated aluminum current collector suitable for positive electrode lithium supplement and a preparation method thereof.The carbon-coated aluminum current collector is composed of an aluminum foil and a grid-shaped active lithium layer and a carbon coating layer arranged on the aluminum foil.The specific steps are as follows:S1: clamp fixing aluminum foil: a square net-shaped clamp is fixed above the aluminum foil, and the clamp is spaced apart from the aluminum foil without overlapping;S2: setting a grid-shaped active lithium layer on the aluminum foil: lithium target material is sputtered onto the lithium supplement active area of the aluminum foil obtained in S1 by magnetron sputtering to obtain a grid-shaped active lithium layer on the aluminum foil;S3: setting a carbon coating layer on the aluminum foil: under the protection of inert gas, conductive slurry is coated in the grid of the grid-shaped active lithium layer to obtain a carbon coating layer on the aluminum foil, and after drying, a carbon-coated aluminum current collector is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current collector preparation, in particular to a carbon-coated aluminum current collector suitable for positive electrode lithium supplement and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of new energy vehicles, the new energy vehicle industry continues to put forward higher requirements for the performance of lithium ion batteries, among which the improvement of battery energy density is the most urgent. In the existing lithium ion battery system, in order to improve the energy density of the battery, the following aspects are mainly considered: on the one hand, the battery structure is optimized to improve the energy density, such as CTP technology, CTC technology, CTB technology, etc.; on the other hand, the positive and negative electrode materials are iterated, such as using high-nickel ternary and high-voltage nickel-manganese materials for the positive electrode, and using high-capacity silicon and tin-based alloy negative electrode for the negative electrode, which can greatly improve the energy density of the battery. In addition, lithium supplement technology for lithium ion batteries is also an important means to improve the energy density of the battery. During the first charging process of the lithium ion battery, the organic electrolyte will be reduced and decomposed on the surface of the graphite negative electrode to form a solid electrolyte interphase (SEI) film, permanently consuming a large amount of lithium from the positive electrode, resulting in a low initial cycle efficiency (ICE) and thus reducing the capacity and energy density of the lithium ion battery. In addition, processes such as deactivation of negative electrode material particles due to shedding and irreversible deposition of lithium metal will also consume active lithium from the positive electrode, reducing the capacity and energy density of the battery.

[0003] Therefore, the present application provides a carbon-coated aluminum current collector suitable for positive electrode lithium supplement, which can supplement the consumed active lithium of the positive electrode, thereby improving the energy density of the battery, and has important practical significance. SUMMARY

[0004] The present application aims to provide a carbon-coated aluminum current collector suitable for positive electrode lithium supplement and a preparation method thereof to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A carbon-coated aluminum current collector suitable for positive electrode lithium supplement is composed of an aluminum foil and a grid-shaped active lithium layer and a carbon coating layer arranged on the aluminum foil.

[0007] The thickness of the aluminum foil is 8-24 μm, and the aluminum foil has two surfaces, A and B.

[0008] The surface A is divided into three parts, A1, A2 and A3, and the surface B is divided into three parts, B1, B2 and B3, as shown in Figure 1 、 Figure 2 .

[0009] The A1, A3 and B1, B3 are tab white area, and the A2 and B2 are lithium supplement active area;

[0010] The grid active lithium layer is obtained by sputtering of a lithium target, is arranged on the lithium supplement active area A2 and B2 of the aluminum foil, and has a thickness of 1±0.2 μm.

[0011] The carbon coating layer is obtained by coating of a conductive paste, is arranged in the grid of the grid active lithium layer, and has a thickness of 1±0.2 μm.

[0012] Further, the grid active lithium layer and the carbon coating layer are arranged on at least one surface of the aluminum foil.

[0013] Further, the carbon coating layer does not cover the grid active lithium layer, that is, the carbon coating layer and the grid active lithium layer are not in direct contact.

[0014] Further, the preparation method of the carbon-coated aluminum current collector comprises the following steps:

[0015] S1: clamp fixing the aluminum foil: a square net-shaped clamp is fixed above the aluminum foil, the clamp is spaced apart from the aluminum foil without overlapping, the spacing is 2-5 mm, and the aluminum foil is prepared for standby;

[0016] S2: arranging the grid active lithium layer on the aluminum foil: a lithium target is sputtered on the lithium supplement active area A2 and B2 of the standby aluminum foil obtained in S1 by magnetron sputtering, and a grid active lithium layer is obtained on the aluminum foil;

[0017] S3: arranging the carbon coating layer on the aluminum foil: under the protection of an inert gas, a conductive paste is coated in the grid of the grid active lithium layer, a carbon coating layer is obtained on the aluminum foil, drying is performed, a carbon-coated aluminum current collector is obtained, and oxygen is avoided to be stored, and the structure is as shown in Figure 3 .

[0018] Further, the dew point temperature of the preparation environment is between-50 and 65℃.

[0019] Further, the baffle of the square net-shaped clamp has a side length of 2-16 mm, is fixed at the middle of the lithium supplement active area A2 and B2 of the aluminum foil, and is spaced apart from the edge of the single-side lithium supplement active area A2 and B2 by 1±0.2 cm.

[0020] Further, the parameters of the magnetron sputtering are as follows: the vacuum degree is 0.5×10 -2 ~5×10 -2 Pa, the target distance is 7-10 cm, the working gas is Ar, the gas flow is 30-100 sccm, the pressure is 0.5-2 Pa, the sputtering power is 90-240 W, the substrate temperature is 25-50℃, and the pre-sputtering time is 20-40 min.

[0021] Further, the conductive paste is composed of the following components mixed: 40-55% of conductive agent, 10-25% of modified binder, 0.5-2% of wetting agent, and 25-40% of solvent by weight percentage.

[0022] Further, the preparation method of the modified binder is as follows: (1) sodium carboxymethyl cellulose is added to deionized water, stirred and mixed uniformly, and dilute hydrochloric acid is added to adjust the pH value to 5-6, to prepare a 0.1-1 g / L sodium carboxymethyl cellulose aqueous solution; (2) 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and N-hydroxysuccinimide are added to the sodium carboxymethyl cellulose aqueous solution, stirred and mixed uniformly, then 5-10 g / L 6-amino-2-mercaptobenzothiazole ethanol solution is added dropwise under nitrogen protection while stirring, after the dropwise addition is completed, the stirring is continued for 1-24 h for reaction, and finally the reaction is ended and the modified sodium carboxymethyl cellulose is obtained by freeze-drying; (3) the modified sodium carboxymethyl cellulose, polyacrylic acid, deionized water, and photoinitiator are stirred and mixed uniformly, irradiated with 350-370 nm ultraviolet light for 1-20 min to end the reaction, and then dried to remove the deionized water to obtain the modified binder.

[0023] Further, the mass ratio of the sodium carboxymethyl cellulose, 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, N-hydroxysuccinimide, and 6-amino-2-mercaptobenzothiazole is 1:(0.75-1):(0.45-0.5):(0.7-1).

[0024] Further, the mass ratio of the modified sodium carboxymethyl cellulose, polyacrylic acid, deionized water, and photoinitiator is (0.1-0.3):5:2:(0.01-0.03).

[0025] The performance of the conductive paste on the current collector determines the electrical conductivity of the electrode, and if the electrical conductivity is too low, it will affect the lithium intercalation and deintercalation, and thus affect the lithium supplement effect, so improving the performance of the conductive paste is the key to promoting lithium supplement. Modification of the binder is usually one of the most effective ways to improve the performance of the conductive paste, therefore, in the scheme, the carboxylic acid group of sodium carboxymethyl cellulose is activated by 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and N-hydroxysuccinimide, and then 6-amino-2-mercaptobenzothiazole is added to combine with it, to obtain modified sodium carboxymethyl cellulose with mercapto groups; finally, under ultraviolet light irradiation conditions, the modified sodium carboxymethyl cellulose and polyacrylic acid undergo click reaction to prepare the modified binder. The modified binder can form strong hydrogen bonds with the conductive agent, making the conductive agent in the carbon coating layer more closely combined, playing a role in enhancing the electrical conductivity of the current collector, and thus enhancing the lithium supplement effect of the current collector.

[0026] Furthermore, the conductive agent includes, but is not limited to, one or a combination of conductive carbon black, conductive graphite, graphene, and carbon nanotubes.

[0027] Furthermore, the wetting agent may be of any one of BYK-ET-3000, BYK-ET-3002, or BYK-HY-1600.

[0028] Furthermore, the solvent includes, but is not limited to, one or more combinations of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, xylene, and acetone.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. The carbon-coated aluminum current collector prepared by this invention improves the coulombic efficiency of the battery;

[0031] 2. The carbon-coated aluminum current collector prepared by this invention can replenish the active lithium consumed during the first charge and discharge cycle, reducing the loss of battery capacity and energy density;

[0032] 3. The carbon-coated aluminum current collector prepared by this invention can replenish the active lithium consumed during the first charge, reduce the irreversible capacity of the battery during the first charge, thereby improving the coulombic efficiency of the battery during the first charge-discharge cycle, ensuring less lithium ion loss at the positive terminal, so as to minimize the impact on battery capacity and energy density, and ultimately achieve the goal of improving battery energy density. Attached Figure Description

[0033] Figure 1 Divide the surface of aluminum foil A;

[0034] Figure 2 Divide the surface of aluminum foil B;

[0035] Figure 3 A schematic diagram of a carbon-coated aluminum current collector;

[0036] in, Figure 3 In the grid, the diagonal lines represent the grid-like active lithium layer; the blank areas represent the carbon coating layer. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In the following examples, all raw materials are sourced as follows: sodium carboxymethylcellulose purity 99%, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride purity 99%, CAS No.: 25952-53-8, N-hydroxysuccinimide purity 98%, CAS No.: 6066-82-6, polyacrylic acid purity 99%, CAS No. 9007-20-9, Item No. 9007-20-9, conductive carbon black purity 99%, N-methylpyrrolidone purity 99%, available from Hubei Yongkong Technology Co., Ltd.;

[0039] 6-amino-2-mercaptobenzothiazole purity 98%, CAS No.: 7442-07-1, available from Shanghai Jinjile Industrial Co., Ltd.;

[0040] Photoinitiator type 1173, purity 99%, available from Hubei Qifei Pharmaceutical Chemical Co., Ltd.;

[0041] BYK-ET-3000 wetting agent, available from Dongguan Huazhiyuan Chemical Co., Ltd.

[0042] Example 1: A preparation method of a carbon-coated aluminum current collector suitable for a positive electrode capable of supplementing lithium:

[0043] S1: Fix the aluminum foil with the clamp: fix the regular quadrilateral mesh clamp with a baffle side length of 2 mm above the middle of the lithium supplementing active area A2, B2 of the aluminum foil with a thickness of 12 μm, the clamp is 1 cm away from the edge of the single-side lithium supplementing active area A2, B2, and the clamp has a 5 mm gap with the aluminum foil, ready for use;

[0044] S2: Set the grid-shaped active lithium layer on the aluminum foil: sputter the lithium target material onto the lithium supplementing active area A2, B2 of the aluminum foil obtained in S1 by magnetron sputtering to obtain a grid-shaped active lithium layer with a thickness of 1 μm on the aluminum foil; wherein the magnetron sputtering parameters are: vacuum degree is 1 × 10 -2 Pa, target distance is 7 cm, working gas is Ar, gas flow is 50 sccm, pressure is 1 Pa, sputtering power is 120 W, substrate temperature is 50°C, and pre-sputtering time is 20 min;

[0045] S3: Set the carbon coating layer on the aluminum foil:

[0046] S31: Preparation of modified binder: (1) 10 parts of sodium carboxymethyl cellulose is added to deionized water, stirred and mixed uniformly, and diluted hydrochloric acid is added to adjust the pH value to 5.5, to prepare a 5 g / L sodium carboxymethyl cellulose aqueous solution; (2) 10 parts of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and 5 parts of N-hydroxysuccinimide are added to the sodium carboxymethyl cellulose aqueous solution, stirred and mixed uniformly, then 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution (8 parts of 6-amino-2-mercaptobenzothiazole is dissolved in anhydrous ethanol to prepare a 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution) is added dropwise under nitrogen protection, after the dropwise addition is completed, the stirring is continued for 24 h, the reaction is completed, and finally the modified sodium carboxymethyl cellulose is obtained by freeze-drying; (3) 2 parts of modified sodium carboxymethyl cellulose, 50 parts of polyacrylic acid, 20 parts of deionized water, and 0.2 parts of a photoinitiator are stirred and mixed uniformly, irradiated with 350 nm ultraviolet light for 15 min, the reaction is completed, and the deionized water is removed by drying to obtain a modified binder;

[0047] S32: Preparation of conductive slurry: the following components are mixed uniformly: by weight percentage, conductive carbon black 50%, modified binder 20%, BYK-ET-3000 type wetting agent 1%, N-methyl pyrrolidone 29%;

[0048] S33: Under nitrogen protection, the conductive slurry is coated in the grid of the grid-shaped active lithium layer, a carbon coating layer with a thickness of 1 μm is obtained on the aluminum foil, it is ensured that the carbon coating layer does not cover the grid-shaped active lithium layer, and after drying, a carbon-coated aluminum current collector is obtained, which is stored in an oxygen-free environment.

[0049] Example 2: A preparation method of a carbon-coated aluminum current collector suitable for a positive electrode that can supplement lithium:

[0050] S1: Clamping the aluminum foil: a square net-shaped clamp with a baffle side length of 5 mm is fixed above the middle of the lithium supplementing active area A2, B2 of the aluminum foil with a thickness of 12 μm, the clamp is 1 cm away from the edge of the single-side lithium supplementing active area A2, B2, and the clamp has a 5 mm gap with the aluminum foil, ready for use;

[0051] S2: Setting a grid-shaped active lithium layer on the aluminum foil: a lithium target is sputtered by magnetron sputtering onto the lithium supplementing active area A2, B2 of the aluminum foil obtained in S1 to obtain a grid-shaped active lithium layer with a thickness of 1 μm on the aluminum foil; wherein the magnetron sputtering parameters are: vacuum degree is 1×10 -2 Pa, target distance is 7 cm, working gas is Ar, gas flow is 50 sccm, pressure is 1 Pa, sputtering power is 120 W, substrate temperature is 50℃, and pre-sputtering time is 20 min;

[0052] S3: Setting a carbon coating layer on the aluminum foil:

[0053] S31: Preparation of modified binder: (1) 10 parts of sodium carboxymethyl cellulose is added to deionized water, stirred and mixed uniformly, and diluted hydrochloric acid is added to adjust the pH value to 5.5, to prepare a 5 g / L sodium carboxymethyl cellulose aqueous solution; (2) 7.5 parts of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and 4.5 parts of N-hydroxysuccinimide are added to the sodium carboxymethyl cellulose aqueous solution, stirred and mixed uniformly, then 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution (7 parts of 6-amino-2-mercaptobenzothiazole is dissolved in anhydrous ethanol to prepare a 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution) is added dropwise under nitrogen protection, after the dropwise addition is completed, the stirring is continued for 24 h, the reaction is completed, and finally the modified sodium carboxymethyl cellulose is obtained by freeze-drying; (3) 1 part of the modified sodium carboxymethyl cellulose, 50 parts of polyacrylic acid, 20 parts of deionized water, and 0.1 part of a photoinitiator are stirred and mixed uniformly, irradiated with 350 nm ultraviolet light for 15 min, the reaction is completed, and the deionized water is removed by drying to obtain a modified binder;

[0054] S32: Preparation of conductive slurry: the following components are mixed uniformly: 50% conductive carbon black, 20% modified binder, 1% BYK-ET-3000 type wetting agent, and 29% N-methyl pyrrolidone by weight percentage;

[0055] S33: The conductive slurry is coated in the grid of the grid-shaped active lithium layer under nitrogen protection, to obtain a carbon coating layer with a thickness of 1 μm on the aluminum foil, ensuring that the carbon coating layer does not cover the grid-shaped active lithium layer, and the carbon-coated aluminum current collector is obtained after drying, and is stored in an oxygen-free environment.

[0056] Example 3: A preparation method of a carbon-coated aluminum current collector suitable for a positive electrode that can supplement lithium:

[0057] S1: Clamping the aluminum foil: a square net-shaped clamp with a baffle side length of 2 mm is fixed above the middle of the lithium supplementing active area A2, B2 of the aluminum foil with a thickness of 12 μm, the clamp is 1 cm away from the edge of the single-side lithium supplementing active area A2, B2, and the clamp is spaced apart from the aluminum foil by 5 mm, ready for use;

[0058] S2: Setting the grid-shaped active lithium layer on the aluminum foil: the lithium target material is sputtered onto the lithium supplementing active area A2, B2 of the aluminum foil obtained in S1 by magnetron sputtering, to obtain a grid-shaped active lithium layer with a thickness of 2 μm on the aluminum foil; wherein the magnetron sputtering parameters are: vacuum degree is 1×10 -2 Pa, target distance is 7 cm, working gas is Ar, gas flow is 50 sccm, pressure is 1 Pa, sputtering power is 120 W, substrate temperature is 50℃, and pre-sputtering time is 40 min;

[0059] S3: Setting a carbon coating layer on the aluminum foil:

[0060] S31: Preparing a modified binder: (1) 10 parts of sodium carboxymethyl cellulose is added to deionized water, stirred and mixed uniformly, and diluted hydrochloric acid is added to adjust the pH value to 5.5, to prepare a 5 g / L sodium carboxymethyl cellulose aqueous solution; (2) 10 parts of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and 5 parts of N-hydroxysuccinimide are added to the sodium carboxymethyl cellulose aqueous solution, stirred and mixed uniformly, then 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution (8 parts of 6-amino-2-mercaptobenzothiazole is dissolved in anhydrous ethanol to prepare a 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution) is added dropwise under nitrogen protection while stirring, after the dropwise addition is completed, the stirring is continued for 24 h to complete the reaction, and finally freeze-drying is performed to obtain the modified sodium carboxymethyl cellulose; (3) 2 parts of the modified sodium carboxymethyl cellulose, 50 parts of polyacrylic acid, 20 parts of deionized water, and 0.2 parts of a photoinitiator are stirred and mixed uniformly, irradiated with 350 nm ultraviolet light for 15 min to complete the reaction, and then dried to remove the deionized water to obtain the modified binder;

[0061] S32: Preparing a conductive slurry: the following components are mixed uniformly: 50% by weight of conductive carbon black, 20% of the modified binder, 1% of BYK-ET-3000 wetting agent, and 29% of N-methyl pyrrolidone;

[0062] S33: The conductive slurry is coated in the grid of the grid-shaped active lithium layer to obtain a carbon coating layer with a thickness of 2 μm on the aluminum foil, ensuring that the carbon coating layer does not cover the grid-shaped active lithium layer, and then dried to obtain a carbon-coated aluminum current collector, which is stored in an oxygen-free environment.

[0063] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustments: the modified binder is not used, and polyacrylic acid is used instead, and the other processes remain unchanged, specifically:

[0064] A method for preparing a carbon-coated aluminum current collector suitable for a positive electrode that can supplement lithium:

[0065] S1: Fixing the aluminum foil with a clamp: a square net-shaped clamp with a baffle edge length of 2 mm is fixed above the middle of the lithium supplementing active area A2, B2 of the aluminum foil with a thickness of 12 μm, the clamp is 1 cm away from the edge of the single-side lithium supplementing active area A2, B2, and the clamp has a 5 mm gap with the aluminum foil, ready for use;

[0066] S2: Setting a grid-shaped active lithium layer on the aluminum foil: a lithium target is sputtered onto the lithium supplementing active area A2, B2 of the aluminum foil obtained in S1 by magnetron sputtering to obtain a grid-shaped active lithium layer with a thickness of 1 μm on the aluminum foil; wherein the magnetron sputtering parameters are: vacuum degree 1 × 10-2 Pa, target distance 7 cm, working gas Ar, gas flow 50 sccm, pressure 1 Pa, sputtering power 120 W, substrate temperature 50°C, pre-sputtering time 20 min;

[0067] S3: setting a carbon coating layer on the aluminum foil:

[0068] S31: preparing a conductive slurry: uniformly mixing the following components: by weight percentage, conductive carbon black 50%, polyacrylic acid 20%, BYK-ET-3000 type wetting agent 1%, N-methyl pyrrolidone 29%;

[0069] S32: under nitrogen protection, coating the conductive slurry in the grid of the grid-shaped active lithium layer on the aluminum foil to obtain a carbon coating layer with a thickness of 1 μm, ensuring that the carbon coating layer does not cover the grid-shaped active lithium layer, and after drying, obtaining a carbon-coated aluminum current collector, which is stored in an oxygen-free environment.

[0070] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustments: no lithium is sputtered on the aluminum foil, and the other processes remain unchanged, specifically:

[0071] A method for preparing a carbon-coated aluminum current collector suitable for a positive electrode that can supplement lithium:

[0072] S1: setting a carbon coating layer on the aluminum foil:

[0073] S11: preparing a modified binder: (1) adding 10 parts of sodium carboxymethyl cellulose to deionized water, stirring and mixing uniformly, and adding dilute hydrochloric acid to adjust the pH value to 5.5 to prepare a 5 g / L sodium carboxymethyl cellulose aqueous solution; (2) adding 10 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 5 parts of N-hydroxysuccinimide to the sodium carboxymethyl cellulose aqueous solution, stirring and mixing uniformly, then maintaining stirring under nitrogen protection, and adding 6 g / L of 6-amino-2-mercaptobenzothiazole ethanol solution (8 parts of 6-amino-2-mercaptobenzothiazole dissolved in anhydrous ethanol to prepare a 6 g / L 6-amino-2-mercaptobenzothiazole ethanol solution) dropwise, after the dropwise addition is completed, continuing to stir for 24 h to end the reaction, and finally freeze-drying to obtain modified sodium carboxymethyl cellulose; (3) stirring and mixing 2 parts of modified sodium carboxymethyl cellulose, 50 parts of polyacrylic acid, 20 parts of deionized water, and 0.2 parts of a photoinitiator uniformly, using 350 nm ultraviolet light for irradiation treatment for 15 min to end the reaction, and drying to remove the deionized water to obtain a modified binder;

[0074] S12: preparing a conductive slurry: uniformly mixing the following components: by weight percentage, conductive carbon black 50%, modified binder 20%, BYK-ET-3000 type wetting agent 1%, N-methyl pyrrolidone 29%;

[0075] S13: Coating conductive paste on the aluminum foil to obtain a carbon coating layer with a thickness of 1 μm, and after drying, a carbon-coated aluminum current collector is obtained.

[0076] Performance test: (1) mixing the lithium iron phosphate material, conductive carbon black, carbon nanotube and polyvinylidene fluoride according to a mass ratio of 95.6:1.3:0.8:2.3, adding an appropriate amount of N-methyl pyrrolidone to obtain a positive electrode slurry; (2) coating the positive electrode slurry on the carbon-coated aluminum current collector prepared in the above examples, and drying at 120℃ to obtain a positive electrode sheet; (3) taking graphite as a negative electrode sheet, a porous PE film as a separator, winding and assembling the positive electrode sheet, the negative electrode sheet and the separator, welding the pole ears, and then packaging in an aluminum plastic film, baking at 100℃ to remove water, injecting a non-aqueous electrolyte (commercial lithium hexafluorophosphate electrolyte), and then sealing, forming, exhausting, and resealing to prepare a lithium ion battery; (4) testing the lithium ion battery for battery performance, testing the coulomb efficiency and 1C capacity; the specific test results are shown in Table 1 below:

[0077] Table 1

[0078]

[0079] Result analysis: From the data in the above Table 1, it can be seen that by thickening the thickness of the grid-shaped active lithium layer and the carbon coating layer and lengthening the side length of the positive quadrilateral mesh clamp baffle, the coulomb efficiency and capacity of the battery are obviously improved; in addition, the modified binder also affects the performance of the battery to some extent.

[0080] It will be obvious to a person skilled in the art that the application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application. Any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. A carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode, characterized in that: The carbon-coated aluminum current collector includes a grid-shaped active lithium layer and a carbon coating layer; wherein, the grid-shaped active lithium layer is obtained by sputtering a lithium target and is disposed on the lithium replenishment active region, with a thickness of 1±0.2μm; the carbon coating layer is obtained by coating with conductive paste and is disposed within the grid of the grid-shaped active lithium layer, with a thickness of 1±0.2μm; the carbon coating layer does not cover the grid-shaped active lithium layer; The conductive paste is composed of a mixture of components including a modified binder; The modified adhesive is prepared as follows: (1) Sodium carboxymethyl cellulose is added to deionized water, stirred and mixed evenly, and dilute hydrochloric acid is added to adjust the pH value to 5~6 to prepare a sodium carboxymethyl cellulose aqueous solution of 0.1~1g / L; (2) 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added to the sodium carboxymethyl cellulose aqueous solution, stirred and mixed evenly, and under nitrogen protection, stirring is maintained and 5~10g / L of 6-amino-2-mercaptobenzothiazole ethanol solution is added dropwise. After the addition is completed, the reaction is continued to be stirred for 1~24h, the reaction is ended, and finally the modified sodium carboxymethyl cellulose is obtained by freeze drying; (3) Modified sodium carboxymethyl cellulose, polyacrylic acid, deionized water and photoinitiator are stirred and mixed evenly, and treated with ultraviolet light of 350~370nm for 1~20min, the reaction is ended, and the modified adhesive is obtained by drying. The mass ratio of sodium carboxymethyl cellulose, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 6-amino-2-mercaptobenzothiazole is 1:(0.75~1):(0.45~0.5):(0.7~1); the ratio of modified sodium carboxymethyl cellulose, polyacrylic acid, deionized water and photoinitiator is (0.1~0.3):5:2:(0.01~0.03).

2. The carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 1, characterized in that: The carbon-coated aluminum current collector also includes an aluminum foil with a thickness of 8~24μm; the grid-like active lithium layer and the carbon coating layer are disposed on at least one surface of the aluminum foil.

3. A carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 2, characterized in that: The aluminum foil is divided into two surfaces, A and B. Surface A is divided into three parts: A1, A2, and A3. Surface B is divided into three parts: B1, B2, and B3. Among them, A1, A3 and B1, B3 are the tab blank areas, and A2 and B2 are the lithium replenishment active areas.

4. A method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to any one of claims 1 to 3, characterized in that: Includes the following steps: S1: Fixing aluminum foil with clamps: Fix a square mesh clamp on top of the aluminum foil. The clamp and the aluminum foil should be spaced apart and not overlap, with a gap of 2~5mm. S2: A grid-like active lithium layer is formed on the aluminum foil: The lithium target is sputtered onto the lithium replenishment active regions A2 and B2 of the aluminum foil obtained in S1 by magnetron sputtering, and a grid-like active lithium layer is obtained on the aluminum foil. S3: Carbon coating layer on aluminum foil: Under the protection of an inert atmosphere, conductive paste is coated in the grid of the grid-like active lithium layer to obtain a carbon coating layer on the aluminum foil. After drying, a carbon-coated aluminum current collector is obtained.

5. The method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 4, characterized in that: The dew point temperature of the preparation environment of this invention is between -50 and 65°C.

6. The method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 4, characterized in that: The parameters for the magnetron sputtering are: vacuum degree of 0.5 × 10⁻⁶. -2 ~5×10 -2 The parameters are: Pa, target spacing 7~10cm, working gas Ar, gas flow rate 30~100sccm, pressure 0.5~2Pa, sputtering power 90~240W, substrate temperature 25~50℃, and pre-sputtering time 20~40min.

7. The method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 4, characterized in that: The baffle of the square mesh fixture has a side length of 2~16mm and is fixed in the middle of the lithium replenishment active areas A2 and B2 of the aluminum foil, with a distance of 1±0.2cm from the edge of the single-sided lithium replenishment active areas A2 and B2.

8. The method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 4, characterized in that: The conductive paste is composed of the following components by weight percentage: 40-55% conductive agent, 10-25% modified binder, 0.5-2% wetting agent, and 25-40% solvent.

9. The method for preparing a carbon-coated aluminum current collector suitable for lithium replenishment at the positive electrode according to claim 8, characterized in that: The conductive agent includes one or a combination of conductive carbon black, conductive graphite, graphene, and carbon nanotubes; the wetting agent includes any one of BYK-ET-3000, BYK-ET-3002, and BYK-HY-1600; the solvent includes one or a combination of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, xylene, and acetone.

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