Carbon-coated aluminum foil, method for manufacturing the same, electrode sheet, and secondary battery

Abstract

The application provides a carbon-coated aluminum foil, a preparation method thereof, an electrode sheet and a secondary battery. The carbon-coated aluminum foil comprises an aluminum foil and a first graphene layer and a second graphene layer arranged on the two sides of the aluminum foil respectively; the first graphene layer and the second graphene layer are doped with nitrogen elements, boron elements and sulfur elements; in the first graphene layer and the second graphene layer, the doping amount of the nitrogen elements is independently 1at% to 10at%, the doping amount of the boron elements is independently 1at% to 5at%, and the doping amount of the sulfur elements is independently 1at% to 3at%. The application synchronously deposits a nitrogen-boron-sulfur co-doped graphene coating layer on both sides of the aluminum foil through structural design, and controls the independent doping range of the nitrogen elements, the boron elements and the sulfur elements, so as to achieve the purposes of adjusting the electronic structure of the graphene layer, introducing defect sites, inhibiting interlayer stacking, enhancing interface chemical bonding and improving surface electrophilicity.

Description

Technical Field

[0001] This invention relates to the field of electrode materials, and more specifically, to a carbon-coated aluminum foil and its preparation method, an electrode sheet, and a secondary battery. Background Technology

[0002] Lithium-ion batteries, as the most mainstream energy storage technology, are widely used in consumer electronics, electric vehicles, and large-scale energy storage systems. Improving their performance remains a core research direction in materials science and electrochemistry. In the structure of a lithium-ion battery, the positive electrode current collector plays multiple roles, including carrying the positive electrode active material, conducting electrons, and supporting the electrode structure. Its performance directly affects the battery's internal resistance, rate characteristics, cycle life, and safety. Currently, high-purity aluminum foil (purity ≥99.9%) is commonly used in industry as the positive electrode current collector due to its good conductivity, low cost, and excellent machinability. However, the naturally occurring dense alumina layer on the surface of the aluminum foil has extremely low electronic conductivity, severely restricting the efficient transport of electrons between the current collector and the active material interface. In addition, the oxide layer is chemically stable and has weak physical adhesion to commonly used cathode materials (such as lithium iron phosphate, nickel cobalt manganese ternary materials, etc.). During the long-term charge and discharge cycle of the battery, the active material is easily detached from the current collector surface due to the influence of volume expansion and contraction stress, which causes the "decarbonization" phenomenon, resulting in accelerated capacity decay, increased internal resistance and deterioration of cycle performance.

[0003] To alleviate the aforementioned problems, the industry commonly employs a "carbon-coated aluminum foil" technology, which involves coating the surface of aluminum foil with a layer of conductive carbon material. Traditional carbon coatings primarily utilize carbonaceous materials such as carbon black, acetylene black, conductive graphite, or graphene, achieved through slurry coating processes (e.g., blade coating, roll coating). However, this solution-based coating process has significant drawbacks: First, carbon materials are prone to agglomeration in solvents, leading to uneven coating distribution, disordered pore structure, and the formation of localized high-resistivity areas. Second, the adhesion between the coating and the aluminum foil substrate relies mainly on physical adsorption or van der Waals forces, lacking chemical bonding, resulting in generally low adhesion and susceptibility to peeling after repeated bending or high-rate charging and discharging. Third, the coating thickness is difficult to control precisely; excessive thickness increases the overall electrode mass and reduces energy density, while insufficient thickness fails to effectively improve interfacial conductivity, resulting in poor process consistency and difficulty meeting the requirements of high-precision battery manufacturing.

[0004] To improve the adhesion and conductivity of the coating to the substrate, some studies have attempted to grow graphene coatings in situ on the surface of aluminum foil using chemical vapor deposition (CVD). While this method can form a continuous, highly conductive carbon network structure, it faces significant technical bottlenecks: CVD processes typically require temperatures above 800°C, while the melting point of aluminum foil is only about 660°C. At this temperature, the substrate is prone to softening, curling, or even melting through, leading to a loss of mechanical strength and rendering the aluminum foil unusable as a current collector. Furthermore, CVD struggles to achieve simultaneous and uniform deposition on both sides of the aluminum foil, usually only processing one side, affecting the overall performance balance of the electrode. Additionally, the slow deposition rate and high equipment cost severely restrict its industrial application.

[0005] In summary, existing technologies, whether traditional coating methods or high-temperature CVD methods, suffer from systemic technical defects such as poor coating uniformity, weak adhesion, incompatible preparation temperatures, limited functionality, and inability to achieve simultaneous modification on both sides. These defects severely restrict the further improvement of the current collector performance of lithium-ion battery cathodes.

[0006] Therefore, how to provide a carbon-coated aluminum foil that can balance high adhesion and high conductivity to fundamentally improve the phenomena of interface transport obstruction and structural failure is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0007] The main objective of this invention is to provide a carbon-coated aluminum foil, its preparation method, electrode sheet, and secondary battery, in order to solve the problem that in the prior art, the carbon layer on the carbon-coated aluminum foil is difficult to achieve both high adhesion and high conductivity, which leads to poor electrochemical performance and cycle stability of the carbon-coated aluminum foil.

[0008] To achieve the above objectives, a first aspect of the present invention provides a carbon-coated aluminum foil, comprising an aluminum foil and a first graphene layer and a second graphene layer respectively disposed on both sides of the aluminum foil; both the first graphene layer and the second graphene layer are doped with nitrogen, boron and sulfur; in the first graphene layer and the second graphene layer, the doping amount of nitrogen is independently 1 at% to 10 at, the doping amount of boron is independently 1 at% to 5 at, and the doping amount of sulfur is independently 1 at% to 3 at.

[0009] Furthermore, the thickness of the aluminum foil is 5μm to 20μm; and / or, the thickness of the first graphene layer and the second graphene layer are each independently 50nm to 2μm; preferably, the purity of aluminum in the aluminum foil is ≥99.9%.

[0010] Furthermore, the resistivity of the first graphene layer and the second graphene layer are each independently 10. -5 Ω·cm~10 -4Ω·cm; and / or, the adhesion between the first graphene layer and the second graphene layer and the aluminum foil is ≥0.1N / mm.

[0011] A second aspect of the present invention provides a method for preparing the above-mentioned carbon-coated aluminum foil, comprising: step S1, performing plasma etching on both sides of the aluminum foil to obtain a first etched surface and a second etched surface; step S2, using plasma-enhanced chemical vapor deposition technology, introducing a reaction gas containing a carbon source, a nitrogen source, a boron source and a sulfur source into a reaction chamber; turning on the plasma power supply, and performing deposition treatment on the first etched surface and the second etched surface to form a first graphene layer and a second graphene layer; wherein the flow rate ratio of the carbon source, nitrogen source, boron source and sulfur source in the reaction gas is 100:(1~10):(1~5):(1~3).

[0012] Further, in step S1, the plasma etching process uses argon as the etching gas, and the flow rate of the etching gas is 20 sccm to 50 sccm; and / or, the etching power of the plasma etching process is 80 W to 150 W, and the etching time is 5 min to 15 min; and / or, the roughness of the first etched surface and the second etched surface are each independently 0.1 μm to 0.5 μm.

[0013] Further, in step S2, the total gas flow rate of the reaction gas is 0.05 sccm to 50 sccm; and / or, the carbon source is selected from one or more of methane, acetylene, and ethylene; and / or, the nitrogen source is selected from one or more of ammonia, nitrogen, and pyridine; and / or, the boron source is borane and / or trimethylborane; and / or, the sulfur source is hydrogen sulfide and / or carbon disulfide.

[0014] Further, in step S2, the deposition treatment time is 30 min to 180 min, and the deposition treatment is carried out at 300℃ to 500℃; and / or, the plasma power of the plasma power supply is 50W to 200W; and / or, the radio frequency power of the plasma power supply is 100W to 1000W, and the electrode spacing is 5mm to 12mm.

[0015] Furthermore, in step S2, during the deposition process, the working pressure of the reaction chamber is 10 Pa to 50 Pa; and / or, before introducing the reaction gas, step S2 further includes evacuating the reaction chamber until the vacuum degree of the reaction chamber is ≤ 5 × 10⁻⁶ Pa. -3 Pa.

[0016] A third aspect of the present invention provides an electrode sheet comprising the aforementioned carbon-coated aluminum foil.

[0017] A fourth aspect of the present invention provides a secondary battery comprising at least one of the aforementioned electrode plates.

[0018] By applying the technical solution of this invention, through the structural design of simultaneously depositing nitrogen, boron, and sulfur co-doped graphene coatings on both sides of an aluminum foil, and controlling the independent doping ranges of nitrogen, boron, and sulfur elements, the aim is to regulate the electronic structure of the graphene layer, introduce defect sites, suppress interlayer stacking, enhance interfacial chemical bonding, and improve surface electrophilicity. The resulting carbonized aluminum foil has advantages such as uniform coating, strong adhesion to the aluminum foil, excellent electronic conductivity, and good electrochemical stability. This achieves the technical effects of significantly reducing the current collector-active material interfacial impedance, improving the adhesion between the coating and the aluminum foil substrate, and improving the long-term cycling stability of the electrode in the electrolyte. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of the carbon-coated aluminum foil provided by the present invention;

[0021] Figure 2 The scanning electron microscope (SEM) characterization results of the carbon-coated aluminum foil obtained in Example 1 of the present invention are shown.

[0022] Figure 3 The SEM characterization results are those of the carbon-coated aluminum foil obtained in Comparative Example 1 of this invention. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0024] As described in the background art, existing carbon-coated aluminum foils suffer from difficulties in simultaneously achieving high adhesion and high conductivity in their carbon layers, resulting in poor electrochemical performance and cycle stability. To address these technical problems, a first aspect of the present invention provides a carbon-coated aluminum foil, comprising an aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22 respectively disposed on both sides of the aluminum foil 10; both the first graphene layer 21 and the second graphene layer 22 are doped with nitrogen, boron, and sulfur; in the first graphene layer 21 and the second graphene layer 22, the nitrogen doping amount is independently 1 at% to 10 at, the boron doping amount is independently 1 at% to 5 at, and the sulfur doping amount is independently 1 at% to 3 at.

[0025] The carbon-coated aluminum foil provided by this invention employs multi-element synergistic doping modification. The introduction of nitrogen, boron, and sulfur elements can effectively regulate the electronic structure of graphene, introduce a large number of defect sites, suppress interlayer stacking of graphene, and simultaneously improve the electronic conductivity and surface hydrophilicity of the coating. Specifically, nitrogen provides additional electron carriers, boron can regulate the Fermi level of graphene and introduce hole carriers, and sulfur can enhance the compatibility of the coating with the electrolyte. The synergistic effect of these three elements significantly improves the overall performance of the carbon-coated aluminum foil.

[0026] Nitrogen atoms, due to their higher electronegativity than carbon, can introduce additional valence electrons when they replace carbon atoms in the graphene lattice to form N–C bonds. This transforms graphene from an intrinsic semiconductor into an n-type conductor, increasing carrier concentration and electron mobility. Within the range of 1 at% to 10 at%, nitrogen doping effectively increases the electron density on the graphene surface, enhances its electrostatic interaction with oxygen atoms in the oxide layer on the aluminum foil surface, promotes the formation of Al–O–N bonds, and thus improves the chemical bonding strength between the coating and the substrate, enhancing the electronic conductivity of the graphene layer. Boron atoms, with fewer valence electrons than carbon, generate hole carriers when they replace carbon atoms in graphene to form B–C bonds, giving graphene p-type conductivity and enhancing the electronic conductivity of the graphene layer. This doping introduces electron-deficient centers, lowers the Fermi level of graphene, enhances its Lewis acid-base interactions with oxygen-containing functional groups, promotes the formation of Al–O–B (BC2O-Al, BCO2-Al) bonds, and thus improves the chemical bonding strength between the coating and the substrate. Within the range of 1 at% to 5 at%, boron doping introduces O heteroatoms, effectively suppressing π–π stacking between graphene sheets and generating numerous defect sites in the graphene, thus increasing the coating porosity and specific surface area. Simultaneously, it avoids structural collapse or interruption of conductive pathways due to excessive boron concentration or the formation of B–B bonds. Sulfur atoms, with their larger radius and lower electronegativity, can form C–S–C structures, introducing greater steric hindrance and polar groups. Within the range of 1 at% to 3 at%, sulfur doping effectively breaks the symmetry of the graphene plane, creating local defect sites in the lattice, enhancing the hydrophilicity of the coating surface, and improving its wettability with polar solvent molecules (such as EC and DMC) in the electrolyte. Simultaneously, the C–S bonds possess certain chemical reactivity, forming Al–O–S bonds with residual hydroxyl groups or oxides on the aluminum foil surface, further strengthening interfacial bonding. In sulfur, boron, and nitrogen co-doped graphene, the three heteroatoms interact with each other to form pyridine nitrogen-boron (PyN-B), NS, or SNC covalent bonds, which significantly increases the doping content of each heteroatom and is more conducive to improving the physicochemical properties of the graphene layer.

[0027] More importantly, within the aforementioned doping concentration range, the three elements work synergistically at the electronic structure (N, B) and surface chemistry (S) levels: nitrogen and boron form an np co-doping system, balancing the overall carrier concentration and maintaining high conductivity; sulfur inhibits interlayer stacking through steric hindrance and polar groups, enhancing the stability of the coating's pore structure; and all three jointly promote the formation of various chemical bonds between graphene and the aluminum foil substrate, such as Al-ON, Al-OB, and Al-OS, achieving a transition from physical adsorption to chemical bonding. This multi-bonding mechanism significantly improves coating adhesion while maintaining low resistivity, without introducing other elements or structural changes beyond this range.

[0028] In general, the carbon-coated aluminum foil provided by the present invention has advantages such as uniform coating, strong adhesion to aluminum foil, excellent electronic conductivity, and good electrochemical stability, thereby achieving the technical effects of significantly reducing the interfacial impedance of the current collector-active material, improving the adhesion between the coating and the aluminum foil substrate, and improving the long-term cycling stability of the electrode in the electrolyte.

[0029] To achieve a better balance between conductivity, mechanical strength, and lightweight, the thickness of the aluminum foil 10 is further preferably 5 μm to 20 μm; and / or, the thicknesses of the first graphene layer 21 and the second graphene layer 22 are each independently 50 nm to 2 μm. Under these preferred dimensional relationships, the two graphene coatings can more uniformly cover the micron-level rough structure on the aluminum foil surface, forming a more complete and continuous conductive path, while maintaining better flexibility and adhesion, thereby promoting higher electrochemical performance of the carbonized aluminum foil. Furthermore, the purity of aluminum in the aluminum foil 10 is preferably ≥99.9%, thereby more effectively suppressing the dissolution behavior of impurity elements (such as Fe, Si, Cu, etc.) in the electrochemical environment, further improving the electrochemical stability of the resulting carbonized aluminum foil.

[0030] In several preferred embodiments, the resistivity of the first graphene layer 21 and the second graphene layer 22 is each independently 10. -5 Ω·cm~10 -4 The adhesion strength between the first graphene layer 21 and the second graphene layer 22 and the aluminum foil 10 is ≥10 N / mm, preferably 12 N / mm to 20 N / mm. In other words, in the carbon-coated aluminum foil provided by this invention, the graphene coating still possesses strong interfacial bonding with the aluminum foil without the use of an adhesive, while also maintaining the intrinsic high conductivity of graphene, thereby more effectively achieving the technical effect of balancing low interfacial impedance and high mechanical stability.

[0031] Specifically, in the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic nitrogen (CN), pyridine nitrogen-boron (PyN-B), NS, and SNC, Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n - (n=1~3), Al–O–S, NS, and SNC bonds exist. The above covalent bonds mean that the three elements directly substitute or bond to the graphene carbon framework, forming a more stable hybrid structure and reducing the migration or precipitation of free elements in the electrolyte.

[0032] A second aspect of the present invention provides a method for preparing the above-mentioned carbon-coated aluminum foil, comprising: step S1, performing plasma etching on both sides of the aluminum foil 10 to obtain a first etched surface and a second etched surface; step S2, using plasma-enhanced chemical vapor deposition (PECVD) to introduce a reaction gas containing a carbon source, a nitrogen source, a boron source and a sulfur source into a reaction chamber; turning on the plasma power supply and performing deposition treatment on the first etched surface and the second etched surface to form a first graphene layer 21 and a second graphene layer 22; wherein the flow rate ratio of the carbon source, nitrogen source, boron source and sulfur source in the reaction gas is 100:(1~10):(1~5):(1~3).

[0033] To address the aforementioned carbon-coated aluminum foil, this invention provides a corresponding preparation method. First, plasma etching is performed on both sides of the aluminum foil. Then, based on PECVD, four-source gases are simultaneously deposited to obtain a high-performance carbon-coated aluminum foil. Furthermore, the above preparation method offers strong process controllability, simple operation, and high deposition efficiency, enabling large-scale production and possessing broad industrial application prospects.

[0034] In step S1, to facilitate the moderate peeling of the oxide layer on the aluminum foil surface without damaging the substrate, and to provide more uniformly distributed nucleation sites for subsequent graphene deposition, thereby further improving coating adhesion and uniformity, preferably: the plasma etching process uses argon as the etching gas, and the flow rate of the etching gas is 20 sccm to 50 sccm; and / or, the etching power of the plasma etching process is 80W to 150W, and the etching time is 5 min to 15 min; and / or, the roughness of the first etched surface and the second etched surface are each independently 0.1 μm to 0.5 μm. Furthermore, to more thoroughly remove surface oil contaminants from the aluminum foil and achieve a stronger bonding effect, before the plasma etching process, step S1 preferably also includes ultrasonic cleaning of the aluminum foil 10, and the ultrasonic cleaning process uses acetone, ethanol, and deionized water as cleaning solutions sequentially, with each cleaning time being 10 min to 20 min.

[0035] Furthermore, in step S2, the total gas flow rate of the reaction gases is preferably 0.05 sccm to 50 sccm, thereby promoting a better kinetic equilibrium in the adsorption-reaction-desorption of the reactants on the aluminum foil substrate surface, allowing the doped graphene layer to grow in a layered epitaxial manner, ultimately obtaining a continuous, high-purity graphene coating with stronger conductivity and adhesion. In practical applications, for the reaction gases, the carbon source is preferably selected from one or more of methane, acetylene, and ethylene; and / or, the nitrogen source is selected from one or more of ammonia, nitrogen, and pyridine; and / or, the boron source is borane and / or trimethylborane; and / or, the sulfur source is hydrogen sulfide and / or carbon disulfide.

[0036] To achieve synergistic optimization of precursor dissociation and surface reaction rate, and to realize atomically controllable deposition, while also more effectively optimizing coating thickness and maintaining the structural stability of the aluminum foil, the deposition time in step S2 is preferably 30 min to 180 min, and the deposition process is carried out at 300℃ to 500℃, ultimately yielding a carbon-coated aluminum foil with better conductivity and cycle stability. Simultaneously, it is preferred that the plasma power of the plasma power source is 50W to 200W; and / or that the radio frequency power of the plasma power source is 100W to 1000W, and the electrode spacing is 5mm to 12mm. Based on the above-preferred plasma condition parameters, the resulting plasma exhibits high uniformity, more stable glow discharge, and more moderate ion energy, which better achieves gentle activation of the aluminum foil substrate surface and low-damage coating growth. This results in obtaining a graphene coating with more consistent thickness and doping uniformity in bifacial symmetrical deposition, ultimately significantly improving the performance of the obtained carbon-coated aluminum foil.

[0037] Furthermore, during the deposition process in step S2, the working pressure of the reaction chamber is preferably 10 Pa to 50 Pa, thereby achieving controllable deposition of graphene coatings with higher purity, lower impurities, and higher crystallinity, and significantly optimizing the electrical properties of the resulting carbon-coated aluminum foil. To more thoroughly eliminate oxygen- and water-containing impurities, thus promoting a purer deposition environment and resulting in a doped graphene layer with superior performance, step S2 preferably includes evacuating the reaction chamber before introducing the reaction gas, until the vacuum level of the reaction chamber is ≤5 × 10⁻⁶. -3 Pa.

[0038] A third aspect of the present invention provides an electrode sheet comprising the aforementioned carbon-coated aluminum foil. Applying the carbon-coated aluminum foil provided by the present invention to the electrode sheet can effectively reduce the interfacial impedance between the current collector and the active material (especially the positive electrode active material), improve electron transport efficiency, enhance interfacial adhesion, and suppress the shedding of active material and the increase in interfacial impedance during charging and discharging, thereby significantly improving the capacity and rate performance of the battery. Furthermore, the coating can effectively prevent corrosion of the aluminum foil in the electrolyte, extending the battery's lifespan. In practical applications, the electrode sheet also includes an active layer disposed on at least one surface of the carbon-coated aluminum foil, the active layer comprising a positive electrode active material, a binder, and a conductive agent. The positive electrode active material can be selected from lithium iron phosphate positive electrode materials or nickel-cobalt-manganese ternary positive electrode materials (NCM).

[0039] A fourth aspect of the present invention provides a secondary battery comprising at least one of the aforementioned electrode sheets. Because the electrode sheets provided by the present invention possess high adhesion, low resistance, and high purity, they can reduce the probability of failures such as interface delamination, poor contact, or metal dissolution caused by current collector failure during battery assembly and cycling, thereby significantly improving the electrical and cycling performance of the resulting secondary battery.

[0040] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] Example 1

[0043] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0044] (1) Pretreatment of aluminum foil substrate: Select aluminum foil with a thickness of 12μm and an Al purity of 99.95%, and clean it by ultrasonication in acetone, ethanol and deionized water for 15 min each, and then dry it at 100℃ for 3 h. Place the dried aluminum foil in a plasma etching device, use argon as the etching gas, gas flow rate of 30 sccm, etching power of 100W and etching time of 10 min to obtain pretreated aluminum foil with both sides being etched surfaces and a surface roughness of 0.1μm.

[0045] (2-1) PECVD deposition preparation: Fix the pretreated aluminum foil onto the double-sided symmetrical deposition fixture of the PECVD equipment, and evacuate the reaction chamber to a vacuum degree of 3×10⁻⁶. -3 Pa.

[0046] (2-2) Coating deposition: Carbon source gas (acetylene), nitrogen source gas (ammonia), boron source gas (borane), and sulfur source gas (hydrogen sulfide) are introduced into the reaction chamber in a flow ratio of 100:20:10:5, with a total flow rate of 20 sccm; the working pressure of the reaction chamber is adjusted to 30 Pa, the temperature is raised to 400 °C, the plasma power supply is turned on, the power is adjusted to 120 W, the radio frequency power is 500 W, the electrode spacing is 8 mm, and the deposition time is maintained for 90 min, and nitrogen, boron, and sulfur doped graphene coatings are deposited simultaneously on both sides of the aluminum foil.

[0047] (2-3) Post-processing: After deposition, the gas source and plasma power supply were turned off, the reaction chamber was allowed to cool naturally to room temperature, and the sample was taken out to obtain nitrogen, boron and sulfur doped graphene-coated aluminum foil.

[0048] The resulting carbon-coated aluminum foil includes an aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 1 μm, respectively disposed on both sides of the aluminum foil 10. The first graphene layer 21 and the second graphene layer 22 are both doped with 5 at% nitrogen, 3 at% boron, and 2 at% sulfur.

[0049] Furthermore, in the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0050] The SEM characterization results of the obtained carbon-coated aluminum foil are shown in the figure. Figure 2 That is, the microstructure of the graphene layer is as follows Figure 2 As shown, graphene exhibits a significant layered structure.

[0051] Example 2

[0052] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0053] (1) Pretreatment of aluminum foil substrate: Select aluminum foil with a thickness of 5μm and an Al purity of 99.9%, and clean it by ultrasonication in acetone, ethanol and deionized water for 10 min each, and then dry it at 80℃ for 4 h. Place the dried aluminum foil in a plasma etching equipment, use argon as the etching gas, gas flow rate of 20 sccm, etching power of 80W and etching time of 15 min to obtain pretreated aluminum foil with both sides being etched surfaces and a surface roughness of 0.3μm.

[0054] (2-1) PECVD deposition preparation: Fix the pretreated aluminum foil onto the double-sided symmetrical deposition fixture of the PECVD equipment, and evacuate the reaction chamber to a vacuum degree of 5×10⁻⁶. -3 Pa.

[0055] (2-2) Coating deposition: Carbon source gas (methane), nitrogen source gas (nitrogen), boron source gas (trimethylboron), and sulfur source gas (carbon disulfide) are introduced into the reaction chamber in a flow ratio of 100:5:20:10, with a total flow rate of 0.05 sccm. The working pressure of the reaction chamber is adjusted to 10 Pa, the temperature is raised to 300℃, the plasma power supply is turned on, the power is adjusted to 50 W, the radio frequency power is 100 W, the electrode spacing is 5 mm, and the deposition time is maintained for 180 min. Nitrogen-boron-sulfur-doped graphene coatings are deposited simultaneously on both sides of the aluminum foil.

[0056] (2-3) Post-processing: After deposition, the gas source and plasma power supply were turned off, the reaction chamber was allowed to cool naturally to room temperature, and the sample was taken out to obtain nitrogen, boron and sulfur doped graphene-coated aluminum foil.

[0057] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 50 nm, respectively disposed on both sides of the aluminum foil 10. In both the first graphene layer 21 and the second graphene layer 22, the nitrogen doping amount is 1 at, the boron doping amount is 5 at, and the sulfur doping amount is 3 at.

[0058] Furthermore, in the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0059] Example 3

[0060] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0061] (1) Pretreatment of aluminum foil substrate: Select aluminum foil with a thickness of 20μm and an Al purity of 99.95%, and clean it by ultrasonication in acetone, ethanol and deionized water for 20 min each, and then dry it at 120℃ for 2 h. Place the dried aluminum foil in a plasma etching device, use argon as the etching gas, gas flow rate of 50 sccm, etching power of 150W and etching time of 5 min to obtain pretreated aluminum foil with both sides being etched surfaces and a surface roughness of 0.5μm.

[0062] (2-1) PECVD deposition preparation: Fix the pretreated aluminum foil onto the double-sided symmetrical deposition fixture of the PECVD equipment, and evacuate the reaction chamber to a vacuum degree of 2×10⁻⁶. -3 Pa.

[0063] (2-2) Coating deposition: Carbon source gas (ethylene), nitrogen source gas (pyridine), boron source gas (borane), and sulfur source gas (hydrogen sulfide) are introduced into the reaction chamber in a flow ratio of 100:30:5:1, with a total flow rate of 50 sccm. The working pressure of the reaction chamber is adjusted to 50 Pa, the temperature is raised to 500 °C, the plasma power supply is turned on, the power is adjusted to 200 W, the radio frequency power is 1000 W, the electrode spacing is 12 mm, and the deposition time is maintained for 30 min. Nitrogen, boron, and sulfur doped graphene coatings are deposited simultaneously on both sides of the aluminum foil.

[0064] (2-3) Post-processing: After deposition, the gas source and plasma power supply were turned off, the reaction chamber was allowed to cool naturally to room temperature, and the sample was taken out to obtain nitrogen, boron and sulfur doped graphene-coated aluminum foil.

[0065] The resulting carbon-coated aluminum foil includes an aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 2 μm, respectively disposed on both sides of the aluminum foil 10. The first graphene layer 21 and the second graphene layer 22 are both doped with 10 at of nitrogen, 1 at of boron, and 1 at of sulfur.

[0066] Furthermore, in the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0067] Example 4

[0068] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0069] The only difference between this embodiment and embodiment 1 is that the gas flow rate of the plasma etching process in step (1) is changed to 10 sccm, the etching power is changed to 180W, and the etching time is changed to 3min.

[0070] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 2 μm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO4). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0071] Example 5

[0072] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0073] The only difference between this embodiment and embodiment 1 is that the gas flow rate of the plasma etching process in step (1) is changed to 60 sccm, the etching power is changed to 50 W, and the etching time is changed to 20 min.

[0074] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 50 nm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0075] Example 6

[0076] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0077] The difference between this embodiment and Embodiment 1 lies only in step (2-1), specifically: the pretreated aluminum foil is fixed on the double-sided symmetrical deposition fixture of the PECVD equipment, and the reaction chamber is evacuated to a vacuum degree of 6×10⁻⁶. -3 Pa.

[0078] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 1 μm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO4). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0079] Example 7

[0080] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0081] The only difference between this embodiment and Embodiment 1 is that in step (2-1), the total flow rate of the reaction gas is changed to 10 sccm.

[0082] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 500 nm, respectively disposed on both sides of the aluminum foil 10.

[0083] Example 8

[0084] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0085] The only difference between this embodiment and Embodiment 1 is that in step (2-1), the total flow rate of the reaction gas is changed to 80 sccm.

[0086] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 3 μm, respectively disposed on both sides of the aluminum foil 10.

[0087] Example 9

[0088] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0089] The only difference between this embodiment and Embodiment 1 is that in step (2-2), the deposition time is changed to 20 min and the deposition temperature is changed to 200℃.

[0090] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 20 nm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0091] Example 10

[0092] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0093] The only difference between this embodiment and Embodiment 1 is that, in step (2-2), the power of the plasma power source is changed to 40 W.

[0094] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 50 nm, respectively disposed on both sides of the aluminum foil 10. Nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic nitrogen (CN), pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO4). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0095] Example 11

[0096] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0097] The only difference between this embodiment and Embodiment 1 is that, in step (2-2), the power of the plasma power source is changed to 250 W.

[0098] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 3 μm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO4). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0099] Example 12

[0100] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0101] The only difference between this embodiment and Embodiment 1 is that, in step (2-2), the working pressure of the reaction chamber is changed to 5 Pa.

[0102] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 20 nm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0103] Example 13

[0104] A structure such as Figure 1 Preparation of carbon-coated aluminum foil as shown:

[0105] The only difference between this embodiment and Embodiment 1 is that, in step (2-2), the working pressure of the reaction chamber is changed to 60 Pa.

[0106] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 3 μm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, nitrogen exists in the form of pyridine nitrogen (CN), pyrrole nitrogen (CN), graphitic (CN) nitrogen, pyridine nitrogen-boron (PyN-B), NS, SNC, and Al–O–N bonds; boron exists in the form of BC3, BC2O, BCO2, pyridine nitrogen-boron (PyN-B), BC2O-Al, and BCO2-Al; and sulfur exists in the form of thiophene sulfur (CSC) and oxidized sulfur (-SO4). n -, n=1~3), Al–O–S, NS and SNC bond forms exist.

[0107] Comparative Example 1

[0108] Preparation of a carbon-coated aluminum foil:

[0109] The only difference between this comparative example and Example 1 is that nitrogen, boron, and sulfur sources were not introduced in step (2-2).

[0110] The resulting carbon-coated aluminum foil includes an aluminum foil and graphene layers, each 1 μm thick, disposed on both sides of the aluminum foil. SEM characterization results are shown below. Figure 3 That is, the microstructure of the graphene layer is as follows: Figure 3 As shown, graphene does not have a significant layered structure.

[0111] Comparative Example 2

[0112] Preparation of a carbon-coated aluminum foil:

[0113] The only difference between this comparative example and Example 1 is that no boron source was introduced in step (2-2).

[0114] Comparative Example 3

[0115] Preparation of a carbon-coated aluminum foil:

[0116] The only difference between this comparative example and Example 1 is that no sulfur source was introduced in step (2-2).

[0117] Comparative Example 4

[0118] Preparation of a carbon-coated aluminum foil:

[0119] The only difference between this comparative example and Example 1 is that in step (2-1), the flow ratio of carbon source gas, nitrogen source gas, boron source gas, and sulfur source gas is changed to 100:12:0.5:0.5.

[0120] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 1 μm, respectively disposed on both sides of the aluminum foil 10. The first graphene layer 21 and the second graphene layer 22 are both doped with 12 at of nitrogen, 0.5 at of boron, and 0.5 at of sulfur.

[0121] Comparative Example 5

[0122] Preparation of a carbon-coated aluminum foil:

[0123] The only difference between this comparative example and Example 1 is that in step (2-1), the flow ratio of carbon source gas, nitrogen source gas, boron source gas, and sulfur source gas is changed to 100:0.5:6:4.

[0124] The resulting carbon-coated aluminum foil includes aluminum foil 10 and a first graphene layer 21 and a second graphene layer 22, each with a thickness of 1 μm, respectively disposed on both sides of the aluminum foil 10. In the first graphene layer 21 and the second graphene layer 22, the nitrogen doping amount is 0.5 at, the boron doping amount is 6 at, and the sulfur doping amount is 4 at.

[0125] Test methods

[0126] The resistivity of the graphene layer was obtained according to T / SPSTS 051-2024 "Carbon-coated aluminum foil for lithium-ion batteries".

[0127] The adhesion between the graphene layer and the aluminum foil was tested according to T / SPSTS 051-2024 "Carbon-coated aluminum foil for lithium-ion batteries".

[0128] Battery sample preparation and performance testing methods: The carbon-coated aluminum foil obtained in each example and comparative example was used as the positive electrode current collector, coated with lithium iron phosphate positive electrode slurry (lithium iron phosphate:PVDF:acetylene black = 95:3:2, solvent: NMP) to prepare the positive electrode sheet. A lithium sheet was used as the negative electrode sheet, Celgard was used as the separator, and 1 mol / L LiPF6 / ethylene carbonate (EC)-dimethyl carbonate (DMC) (EC and DMC mass ratio 1:1) was used as the electrolyte to assemble CR2032 type lithium-ion batteries. Then, at a temperature of 25℃ and a voltage range of 2.8V~3.8V, the initial discharge capacity at 0.5C, the capacity retention after 500 cycles at 0.5C, and the discharge capacity at 10C were tested for each battery sample.

[0129] The test results are shown in Table 1.

[0130] Table 1

[0131]

[0132] As can be seen from the above description, compared with the comparative examples, the embodiments of the present invention achieve the preparation of high-performance carbon-coated aluminum foil. The obtained carbon-coated aluminum foil has advantages such as uniform coating, strong adhesion to aluminum foil, excellent electronic conductivity, and good electrochemical stability, thereby achieving the technical effects of significantly reducing the interfacial impedance of the current collector-active material, improving the adhesion between the coating and the aluminum foil substrate, and improving the long-term cycling stability of the electrode in the electrolyte.

[0133] Specifically, in each embodiment:

[0134] Comparing Examples 4 and 5 with Example 1, it can be seen that by optimizing the conditions and parameters of plasma etching, the oxide layer on the surface of the aluminum foil can be appropriately peeled off without damaging the substrate, while also providing more uniformly distributed nucleation sites for subsequent graphene deposition, thereby further improving the adhesion and uniformity of the coating.

[0135] Comparing Example 6 with Example 1, it can be seen that, before introducing the reaction gas, step S2 preferably further includes evacuating the reaction chamber until the vacuum degree of the reaction chamber is ≤5×10⁻⁶. -3 Pa can more thoroughly remove oxygen- and water-containing impurities, thus promoting a purer deposition environment, resulting in a doped graphene layer with superior performance.

[0136] Comparing Examples 7 and 8 with Example 1, it can be seen that by optimizing the total flow rate of the reactant gas, a better kinetic balance can be achieved in the adsorption-reaction-desorption of the reactants on the surface of the aluminum foil substrate, allowing the doped graphene layer to grow in a layered epitaxial manner, ultimately obtaining a continuous, high-purity graphene coating with stronger conductivity and adhesion.

[0137] Comparing Example 9 with Example 1, it can be seen that by optimizing the deposition time and deposition temperature, the precursor dissociation and surface reaction rate can be synergistically optimized, atomically controllable deposition can be achieved, and the coating thickness can be optimized more effectively, maintaining the structural stability of the aluminum foil, ultimately resulting in a carbon-coated aluminum foil with better conductivity and cycle stability.

[0138] Comparing Examples 10 and 11 with Example 1, it can be seen that by optimizing the power of the plasma power source, it is possible to achieve better gentle activation of the aluminum foil substrate surface and low-damage growth of the coating, thereby achieving a graphene coating with more consistent thickness and doping uniformity in double-sided symmetrical deposition, and ultimately significantly improving the performance of the obtained carbon-coated aluminum foil.

[0139] Comparing Examples 12 and 13 with Example 1, it can be seen that by optimizing the working pressure of the reaction chamber, controllable deposition of graphene coatings with higher purity, lower impurities, and higher crystallinity can be achieved, and the electrical properties of the resulting carbon-coated aluminum foil can be optimized more significantly.

[0140] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0141] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A carbon-coated aluminum foil, characterized in that, It includes an aluminum foil (10) and a first graphene layer (21) and a second graphene layer (22) respectively disposed on both sides of the aluminum foil (10); Both the first graphene layer (21) and the second graphene layer (22) are doped with nitrogen, boron and sulfur. In the first graphene layer (21) and the second graphene layer (22), the amount of nitrogen doping is 1 at% to 10 at, the amount of boron doping is 1 at% to 5 at, and the amount of sulfur doping is 1 at% to 3 at.

2. The carbon-coated aluminum foil according to claim 1, characterized in that, The aluminum foil (10) has a thickness of 5 μm to 20 μm; and / or, The thickness of the first graphene layer (21) and the second graphene layer (22) are each independently 50 nm to 2 μm; Preferably, the aluminum in the aluminum foil (10) has a purity of ≥99.9%.

3. The carbon-coated aluminum foil according to claim 1 or 2, characterized in that, The resistivity of the first graphene layer (21) and the second graphene layer (22) is independently 10. -5 Ω·cm~10 -4 Ω·cm; and / or, The adhesion between the first graphene layer (21) and the second graphene layer (22) and the aluminum foil (10) is ≥10N / mm.

4. A method for preparing carbon-coated aluminum foil according to any one of claims 1 to 3, characterized in that, include: Step S1: Plasma etching is performed on both sides of the aluminum foil (10) to obtain a first etched surface and a second etched surface. Step S2: Using plasma-enhanced chemical vapor deposition (PECVD), a reaction gas containing a carbon source, a nitrogen source, a boron source, and a sulfur source is introduced into the reaction chamber; the plasma power supply is turned on, and deposition is performed on the first etched surface and the second etched surface to form the first graphene layer (21) and the second graphene layer (22). In the reaction gas, the flow rate ratio of the carbon source, the nitrogen source, the boron source and the sulfur source is 100:(1~10):(1~5):(1~3).

5. The method for preparing carbon-coated aluminum foil according to claim 4, characterized in that, In step S1 The plasma etching process uses argon as the etching gas, and the flow rate of the etching gas is 20 sccm to 50 sccm; and / or, The plasma etching process has an etching power of 80W~150W and an etching time of 5min~15min; and / or, The roughness of the first etched surface and the second etched surface are each independently 0.1 μm to 0.5 μm.

6. The method for preparing carbon-coated aluminum foil according to claim 4 or 5, characterized in that, In step S2 The total gas flow rate of the reacting gases is 0.05 sccm to 50 sccm; and / or, The carbon source is selected from one or more of methane, acetylene, and ethylene; and / or, The nitrogen source is selected from one or more of ammonia, nitrogen, and pyridine; and / or, The boron source is borane and / or trimethylborane; and / or, The sulfur source is hydrogen sulfide and / or carbon disulfide.

7. The method for preparing carbon-coated aluminum foil according to any one of claims 4 to 6, characterized in that, In step S2 The deposition treatment time is 30 min to 180 min, and the deposition treatment is carried out at 300℃ to 500℃; and / or, The plasma power supply has a plasma power of 50W~200W; and / or, The plasma power source has a radio frequency power of 100W~1000W and an electrode spacing of 5mm~12mm.

8. The method for preparing carbon-coated aluminum foil according to any one of claims 4 to 7, characterized in that, In step S2 During the deposition process, the working pressure of the reaction chamber is 10 Pa to 50 Pa; and / or, Before introducing the reaction gas, step S2 further includes evacuating the reaction chamber until the vacuum level of the reaction chamber is ≤5×10⁻⁶. -3 Pa.

9. An electrode sheet, characterized in that, The electrode sheet includes carbon-coated aluminum foil as described in any one of claims 1 to 3.

10. A secondary battery, characterized in that, The secondary battery includes at least one electrode sheet as described in claim 9.

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