Highly conductive carbon-coated aluminum foil for lithium battery and process for preparing the same

Abstract

A kind of high conductivity carbon-coated aluminum foil for lithium battery and its preparation process, including substrate material and plating layer, the substrate material is selected thickness aluminum alloy film;Wherein the thickness of plating layer is 800-2800nm, the thickness of plating layer accounts for 1 / 20-1 / 10 of the thickness of overall carbon-coated aluminum foil, SiC accounts for 15%-20% in plating layer by weight percentage, and the rest components are one or mixture of metal oxide, metal hydride, metal carbide or metal complex.Compared with the structure form and process of existing carbon-coated aluminum foil, the scheme can improve the conductivity of substrate material by depositing SiC layer on the surface of aluminum alloy film, and can enhance the thermal stability and chemical stability of carbon-coated aluminum foil by high-temperature sintering treatment and chemical etching step, so that it is more reliable in the operation process of lithium battery.

Description

Technical Field

[0001] This article specifically relates to a highly conductive carbon-coated aluminum foil for lithium batteries and its preparation process. Background Technology

[0002] Battery foil, as a lightweight and high-strength material, is widely used in the new energy industry, especially as a separator material in lithium batteries or other new types of batteries.

[0003] The current mainstream research and development direction is to enhance the physical and chemical properties of this special aluminum foil, namely battery foil, especially to increase the conductivity of the battery foil, thereby reducing the internal resistance of the battery and improving the charging and discharging efficiency of the battery.

[0004] In addition to improving the pinhole defects, density, uniformity, and additive dispersion morphology of aluminum foil itself, research on surface coatings for aluminum foil is becoming increasingly extensive. In particular, research on carbon-coated aluminum foil is currently a mainstream research direction.

[0005] The main problem to be solved at present is how to improve the stability of carbon-coated aluminum foil and ultimately improve the conductivity of aluminum foil by stabilizing and firmly coating the carbon layer. Summary of the Invention

[0006] To address the aforementioned issues, this paper proposes a highly conductive carbon-coated aluminum foil for lithium batteries and its preparation process, as detailed below:

[0007] A highly conductive carbon-coated aluminum foil for lithium batteries includes a substrate material and a coating layer, wherein the substrate material is an aluminum alloy film of a selected thickness.

[0008] The thickness of the coating layer is 800-2800 nm, and the thickness of the coating layer accounts for 1 / 20-1 / 10 of the overall thickness of the carbon-coated aluminum foil. Calculated by weight percentage, SiC accounts for 15%-20% of the coating layer, and the remaining components are one or a mixture of metal oxides, metal hydrides, metal carbides or metal complexes.

[0009] Furthermore, the aluminum alloy film is of model number 1070, 1060, 3003 or 1100.

[0010] Furthermore, this includes the following steps:

[0011] S1. Select aluminum foil of a certain thickness as the base material according to the technical requirements;

[0012] S2. Prepare for vacuum coating by evacuating the vacuum chamber to a vacuum level of 10. -3 Up to 10 -6 Between MPa;

[0013] S3. Select a suitable carbon source material and place it in the evaporation source of the coating chamber;

[0014] S4. The evaporation source is heated to the evaporation temperature of the carbon source material, and deposited on the surface of the substrate material by magnetron sputtering, thereby controlling the evaporation rate and growth rate to control the uniformity of the coating.

[0015] S5. After the magnetron coating is completed, a SiC layer is formed. Then, one or a mixture of metal oxides, metal hydrides, metal carbides or metal complexes are deposited on the SiC layer by chemical vapor deposition.

[0016] S6. After natural cooling, the coating is cured.

[0017] S7. Post-processing: High-stability carbon-coated aluminum foil is obtained through annealing.

[0018] Furthermore, curing the coating includes the following steps:

[0019] S61. The coated aluminum foil is sintered.

[0020] S62. After sintering, chemical etching is performed on the surface of the aluminum foil;

[0021] S63. After etching, the sol is evenly coated on the surface of the pretreated carbon-coated aluminum foil.

[0022] S64. Forms a uniform antioxidant film structure.

[0023] The coating process parameters are as follows: first positive coating: 110±5℃; second positive coating: 120±5℃; third positive coating: 120±5℃; fourth positive coating: 110±5℃; first reverse coating: 110±5℃; second reverse coating: 120±5℃; third reverse coating: 120±5℃; fourth reverse coating: 110±5℃.

[0024] Furthermore, the preparation process of the sol in S63 includes slowly dissolving a certain amount of alumina precursor in an organic solvent; adding an appropriate amount of deionized water to adjust the solid content to 10-20 wt%; catalytic hydrolysis: adding a certain amount of nitric acid or acetic acid solution to the solution, and aging the sol under constant temperature conditions to promote particle growth and aggregation in the sol.

[0025] Furthermore, the organic solvent is ethanol (C2H5OH) or acetone (CH3COCH3).

[0026] Furthermore, the alumina precursor is aluminum isopropoxide (Al(OiPr)3) or aluminum acetate (Al(OAc)3).

[0027] Furthermore, in S7, the annealing process includes pre-drying the sol-coated aluminum foil at a temperature below 100 degrees Celsius to remove the solvent and some moisture; then, the pre-dried aluminum foil is subjected to high-temperature treatment at 300-600 degrees Celsius.

[0028] Furthermore, tests were conducted on the carbon-coated aluminum foil with an alumina coating to assess its antioxidant properties, adhesion, and electrical conductivity.

[0029] Beneficial effects:

[0030] Compared with existing carbon-coated aluminum foil structures and processes, this solution improves the conductivity of the substrate material by depositing a SiC layer on the surface of the aluminum alloy film. Furthermore, the thermal and chemical stability of the carbon-coated aluminum foil can be enhanced through high-temperature sintering and chemical etching steps, making it more reliable during lithium battery operation.

[0031] To prevent oxidation damage to the product during prolonged use, an alumina precursor sol is coated onto the surface of the carbon-coated aluminum foil, forming a uniform anti-oxidation film structure. This effectively prevents the aluminum foil from oxidizing at high temperatures, extending battery life. Furthermore, pretreatment of the aluminum foil surface and sol coating improve the adhesion between the coating and the substrate material, ensuring the stability of the carbon-coated aluminum foil during use.

[0032] Moreover, by adjusting the thickness of the SiC layer and selecting different metal oxides, hydrides, carbides, or complexes, the performance of carbon-coated aluminum foil can be customized to meet the needs of different application scenarios, thus giving it a wider range of application prospects. Detailed Implementation

[0033] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0034] Example 1:

[0035] I. Material Selection and Preparation

[0036] A 1070 type aluminum alloy film with a thickness of 50 micrometers was selected as the substrate material.

[0037] High-purity graphite is selected as the carbon source material.

[0038] The metal oxide is aluminum oxide (Al2O3), prepared from the aluminum isopropoxide (Al(OiPr)3) precursor.

[0039] II. Preparation Process

[0040] (1) Substrate material preparation: Cut the 1070 aluminum alloy film into the required size and remove surface impurities by ultrasonic cleaning.

[0041] (2) Vacuum coating preparation: In the vacuum coating equipment, a vacuum of 10 is drawn. -4 MPa.

[0042] (3) Carbon coating: Graphite is placed in an evaporation source and heated to 2500℃ to evaporate the graphite. Graphite vapor is deposited on the surface of aluminum foil using magnetron sputtering technology to form a carbon layer with a thickness of 1200nm.

[0043] (4) SiC layer formation: After the carbon coating is completed, a SiC layer with a thickness of about 200 nm is formed at 800 °C by using SiCl4 and CH4 as reaction gases through chemical vapor deposition.

[0044] (5) Coating curing:

[0045] a. Sintering treatment of the coated aluminum foil;

[0046] b. After sintering, chemical etching is performed on the surface of the aluminum foil;

[0047] c. After etching, the sol is evenly coated onto the surface of the pretreated carbon-coated aluminum foil.

[0048] d. Formation of a uniform antioxidant film structure;

[0049] The sol-gel method was used to dissolve Al(OiPr)3 in ethanol to form a sol. The coating process parameters were as follows: first forward coating: 110±5℃; second forward coating: 120±5℃; third forward coating: 120±5℃; fourth forward coating: 110±5℃; first reverse coating: 110±5℃; second reverse coating: 120±5℃; third reverse coating: 120±5℃; fourth reverse coating: 110±5℃.

[0050] (6) Post-treatment: High-temperature annealing at 450℃ for 2 hours.

[0051] Example 2:

[0052] I. Material Selection and Preparation

[0053] Aluminum alloy film of type 3003 with a thickness of 40 micrometers was selected.

[0054] High-purity carbon nanotubes are selected as the carbon source material.

[0055] Metal hydrides were chosen as coating materials, with TiH2 being the primary choice.

[0056] II. Preparation Process

[0057] (1) Substrate material preparation: 3003 aluminum alloy film is mechanically polished and chemically etched.

[0058] (2) Vacuum coating preparation: Evacuate the vacuum to 10 -5 MPa.

[0059] (3) Carbon coating: Carbon nanotubes are evaporated at 950℃ and carbon layer is deposited by magnetron sputtering technology with a thickness of 1500nm.

[0060] (4) SiC layer formation: A SiC layer is generated by reacting SiH4 and C2H6 at 700℃, with a deposition thickness of approximately 300 nm. A TiH2 layer with a thickness of approximately 500 nm is deposited on the SiC layer using physical vapor deposition (PVD) technology.

[0061] (5) Coating curing:

[0062] a. Sintering treatment of the coated aluminum foil;

[0063] b. After sintering, chemical etching is performed on the surface of the aluminum foil;

[0064] c. After etching, the sol is evenly coated onto the surface of the pretreated carbon-coated aluminum foil.

[0065] d. Formation of a uniform antioxidant film structure;

[0066] The sol-gel method was used to dissolve Al(OiPr)3 in ethanol to form a sol. The coating process parameters were as follows: first forward coating: 110±5℃; second forward coating: 120±5℃; third forward coating: 120±5℃; fourth forward coating: 110±5℃; first reverse coating: 110±5℃; second reverse coating: 120±5℃; third reverse coating: 120±5℃; fourth reverse coating: 110±5℃.

[0067] (6) Post-treatment: anneal at 500°C for 2 hours to enhance the structural stability of the coating.

[0068] Example 3:

[0069] I. Material Selection and Preparation

[0070] A 1060 type aluminum alloy film with a thickness of 30 micrometers was selected.

[0071] Carbon black was selected as the carbon source material.

[0072] The metal complex is Co(acac)3.

[0073] II. Preparation Process

[0074] (1) Substrate material preparation: 1060 aluminum alloy film is annealed and surface activated.

[0075] (2) Vacuum coating preparation: Adjust the vacuum level to 10 -3 MPa.

[0076] (3) Carbon coating: Carbon black is evaporated at 1200℃ and a thin film is formed by magnetron coating technology with a thickness of about 1000nm.

[0077] (4) SiC layer formation: A SiC layer with a thickness of approximately 250 nm is generated by reacting Si(CH3)4 and C2H2 at 600 °C. A CoO layer with a thickness of approximately 600 nm is then deposited on the SiC layer using chemical vapor deposition to form Co(acac)3.

[0078] (5) Coating curing:

[0079] a. Sintering treatment of the coated aluminum foil;

[0080] b. After sintering, chemical etching is performed on the surface of the aluminum foil;

[0081] c. After etching, the sol is evenly coated onto the surface of the pretreated carbon-coated aluminum foil.

[0082] d. Formation of a uniform antioxidant film structure;

[0083] The sol-gel method was used to dissolve Al(OiPr)3 in ethanol to form a sol. The coating process parameters were as follows: first forward coating: 110±5℃; second forward coating: 120±5℃; third forward coating: 120±5℃; fourth forward coating: 110±5℃; first reverse coating: 110±5℃; second reverse coating: 120±5℃; third reverse coating: 120±5℃; fourth reverse coating: 110±5℃.

[0084] (6) Post-treatment: High-temperature annealing at 550℃ for 1 hour to improve the stability and adhesion of the coating.

[0085] Comparative Example 1:

[0086] The preparation method is the same as in the example, except that a SiC layer is not deposited on the carbon-coated aluminum foil.

[0087] Comparative Example 2:

[0088] The preparation method is the same as in the examples, except that the aluminum oxide precursor sol is not coated on the surface of the carbon-coated aluminum foil.

[0089] The oxidation resistance, adhesion, and conductivity of the carbon-coated aluminum foils obtained in Examples 1-3 and Comparative Examples 1 and 2 were tested, and the test results are as follows:

[0090]

[0091] The data above shows that the optimized technical solution of the embodiments can significantly improve the oxidation resistance, adhesion and conductivity of aluminum foil.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of high conductivity carbon coated aluminum foil for lithium batteries, characterized in that, The method comprises the following steps: S1, selecting aluminum foil with a certain thickness as a base material according to technical requirements; S2, vacuum coating preparation, vacuum degree in the vacuum chamber is extracted to 10 -3 to 10 -6 Mpa between; S3, selecting a suitable carbon source material and placing the carbon source material in an evaporation source of a coating chamber; S4, heating the evaporation source to the evaporation temperature of the carbon source material, and depositing on the surface of the base material by a magnetron mode, controlling the evaporation rate and the growth rate to control the uniformity of the coating; S5, after the magnetron coating is completed, forming a SiC layer, and depositing metal oxide, metal hydride or a mixture on the SiC layer by a chemical vapor deposition mode; S6, solidifying the coating after natural cooling; S7, post-processing, obtaining a high-stability carbon-coated aluminum foil by annealing treatment; The solidification of the coating comprises the following steps: S61, sintering treatment is performed on the aluminum foil after coating; S62, after sintering is completed, chemical etching is performed on the surface of the aluminum foil; S63, after etching is completed, sol is uniformly coated on the surface of the pretreated carbon-coated aluminum foil; S64, forming a uniform oxidation-resistant film structure; The coating process parameters are as follows: first positive coating: 110±5℃; second positive coating: 120±5℃; third positive coating: 120±5℃; fourth positive coating: 110±5℃; first negative coating: 110±5℃; second negative coating: 120±5℃; third negative coating: 120±5℃; fourth negative coating: 110±5℃; The preparation process of the sol in S63 comprises slowly dissolving a certain amount of aluminum oxide precursor in an organic solvent; adding a proper amount of deionized water to adjust the solid content to 10-20wt%; catalytic hydrolysis: adding a certain amount of nitric acid or acetic acid solution dropwise into the solution, and allowing the sol to perform aging treatment under constant temperature conditions to promote the growth and agglomeration of particles in the sol.

2. The process for preparing a high conductivity carbon coated aluminum foil for lithium battery as claimed in claim 1 wherein, The organic solvent is ethanol (C2H5OH) or acetone (CH3COCH3).

3. The process for preparing high conductivity carbon coated aluminum foil for lithium battery as claimed in claim 1 wherein, The aluminum oxide precursor is aluminum isopropylate (Al(OiPr)3) or aluminum acetate (Al(OAc)3).

4. The process for preparing a high conductivity carbon coated aluminum foil for lithium battery as claimed in claim 1 wherein, In S7, the annealing treatment comprises pre-drying the aluminum foil coated with the sol below 100℃ to remove the solvent and part of the moisture; and then performing high-temperature treatment on the pre-dried aluminum foil at 300-600℃.

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