Method for preparing aluminum foil current collector, aluminum foil current collector, positive electrode sheet and lithium ion battery

Abstract

The application provides a preparation method of an aluminum foil current collector, an aluminum foil current collector, a positive pole piece and a lithium ion battery, and relates to the technical field of new materials for energy storage devices. The preparation method of the aluminum foil current collector comprises the following steps: performing pretreatment on the surface of a base material aluminum foil with a purity of 99.7% or above, so that the surface reaches a du Nouy value of 64 dyne / cm or above, to obtain a pretreated base material aluminum foil; performing electrochemical etching treatment on the pretreated base material aluminum foil, to obtain an etched base material aluminum foil; performing cleaning on the etched base material aluminum foil, and then performing post-treatment, so that a phosphating film is formed on the surface, to obtain the aluminum foil current collector. The preparation method of the aluminum foil current collector is an etched aluminum foil current collector for high-safety lithium ion batteries and a preparation method, and can solve the problems that the safety is not good enough when a conventional current collector is used to prepare a lithium ion battery, and the mechanical property of a high-purity aluminum foil is poor after etching.

Description

Technical Field

[0001] This invention relates to the field of new materials technology for energy storage devices, and in particular to a method for preparing an aluminum foil current collector, the aluminum foil current collector, the positive electrode sheet, and a lithium-ion battery. Background Technology

[0002] As the global energy structure transitions towards a green and low-carbon model, lithium-ion batteries, as highly efficient energy storage carriers, have been widely used in consumer electronics, electric vehicles (EVs), and large-scale energy storage systems (ESS). However, their widespread application is always accompanied by severe safety challenges. Battery thermal runaway is the most serious safety accident involving lithium-ion batteries, and once it occurs, it can lead to catastrophic consequences such as fires and explosions. Among the many factors that cause thermal runaway, internal short circuits are considered one of the most critical and direct triggering factors.

[0003] Traditional current collectors (aluminum foil for the positive electrode and copper foil for the negative electrode) are key components inside the battery that carry active materials and collect current. However, under conditions of battery abuse (such as mechanical abuse, overcharging, and overheating), they may become "amplifiers" of safety hazards.

[0004] To fundamentally improve the intrinsic safety of batteries, developing highly safe functional current collectors has become a consensus and a key research focus in academia and industry. The core design concept is to endow the current collector with the ability to actively defend against abuse conditions. That is, at the instant a short circuit occurs, it can rapidly cut off the current or increase the resistance through its own physicochemical changes, thereby preventing further heat accumulation and blocking the thermal runaway chain reaction.

[0005] CN120657136A discloses a method for controlling the surface wettability of an ultrathin aluminum foil current collector, comprising the following steps: (1) cleaning the aluminum foil with alcohol and drying it; (2) using the cleaned ultrathin aluminum foil as the anode, graphite, platinum sheet, stainless steel or aluminum foil as the cathode, and an iron nitrate-based metal salt solution containing complexing agent, surfactant and preservative as the electrolyte, with the iron nitrate solution concentration being 0.01~1 mol / L, electrochemically etching the anode aluminum foil to perform electrochemical treatment; simultaneously, using ultraviolet light as the radiation source, the aluminum foil surface is treated during the etching process; (3) cleaning and drying the treated aluminum foil with deionized water. This invention only focuses on controlling the surface wettability of ultrathin aluminum foil, and the iron nitrate-based electrolyte is prone to residual iron ions, which can trigger internal side reactions in the battery, affecting cycle and safety.

[0006] Furthermore, although the aforementioned invention discloses the use of etching to process aluminum foil, ordinary industrial aluminum foil contains small amounts of impurities such as Fe, Si, and Cu. These atoms embed themselves in the aluminum lattice to form solid solutions or form fine intermetallic compounds (such as the Al-Fe-Si phase) with aluminum. These substances hinder dislocation movement, essentially "reinforcing" the aluminum matrix and thus increasing tensile strength. However, for high-purity aluminum foil, the impurity content is extremely low, and the solid solution strengthening and dispersion strengthening effects are almost non-existent. The resistance to dislocation movement is small, making it prone to plastic deformation under external forces, thus significantly reducing tensile strength. In addition, high-purity aluminum grains grow more easily and have more uniform grain size, resulting in a relatively fewer grain boundaries. Grain boundaries themselves hinder dislocation movement; the fewer grain boundaries there are, the smoother the dislocation slip, the weaker the material's resistance to deformation, and the lower the tensile strength.

[0007] Therefore, it is more difficult to uniformly etch high-purity aluminum foil, mainly because: 1. The surface composition of high-purity aluminum is highly uniform with no obvious differences in active sites. The etching reaction relies entirely on the direct reaction between the aluminum substrate and the electrolyte, which easily leads to local "pitting" or "uneven dissolution"; 2. High-purity aluminum has large grain size and significant differences in crystal orientation between different grains. The dissolution rate of the close-packed surface (such as the (111) surface) and the non-close-packed surface (such as the (100) surface) of aluminum in the electrolyte is different. The etching rate of grains with different orientations is large, which eventually results in an uneven surface and makes it impossible to form a uniform porous structure or etching morphology; 3. High-purity aluminum is easy to form a dense and uniform aluminum oxide passivation film. The dissolution rate of this film in the etching solution is slow and unstable. The damaged part of the local film will become the etching breakthrough point, causing local rapid dissolution, while the etching of the intact area of ​​the film will stagnate, further aggravating the uneven etching.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing an aluminum foil current collector, an aluminum foil current collector, a positive electrode sheet, and a lithium-ion battery. The method for preparing the aluminum foil current collector is a high-safety etchable aluminum foil current collector for lithium-ion batteries and its preparation method, thereby solving the technical problems of insufficient safety in the preparation of lithium-ion batteries using existing conventional current collectors and the difficulty in achieving good etching results with high-purity aluminum foil.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing an aluminum foil current collector, the method comprising: The surface of the substrate aluminum foil with a purity of 99.7% or higher is pretreated until the dyne value of its surface is 64 dyne / cm or higher, and the pretreated substrate aluminum foil is obtained. The pretreated aluminum foil substrate is subjected to electrochemical etching to obtain the etched aluminum foil substrate. After cleaning the etched aluminum foil substrate, post-processing is performed until a phosphate film is formed on its surface to obtain the aluminum foil current collector.

[0011] Furthermore, the thickness of the substrate aluminum foil is 12~19 μm.

[0012] Furthermore, the copper content in the aluminum foil substrate is <500 ppm.

[0013] Furthermore, the iron content in the aluminum foil substrate is <1500 ppm.

[0014] Furthermore, the pretreatment method includes physical methods and / or chemical methods.

[0015] Furthermore, the physical methods include corona and / or plasma cleaning.

[0016] Furthermore, the chemical method includes acid leaching and / or alkali leaching.

[0017] Furthermore, the etched substrate aluminum foil has a uniformly rough surface with an average depth of 0.3~2.3 μm.

[0018] Furthermore, the electrochemical etching process is performed 1 to 3 times.

[0019] Furthermore, the temperature of the electrochemical etching process is 36~47℃.

[0020] Furthermore, the alternating current applied during the electrochemical etching process has a frequency of 12–50 Hz and a current density of 0.05–0.5 A / cm². 2 The power-on time is 5~40 s.

[0021] Furthermore, the total acidity of the etching solution used in the electrochemical etching process is 2~3 N.

[0022] Furthermore, the etching solution comprises, by molar concentration meter: 1.9~2.9 mol / L hydrochloric acid, 0.01~0.3 mol / L sulfuric acid, 0.01~1 mol / L aluminum salt, and water as the solvent.

[0023] Furthermore, the aluminum salt in the etching solution is aluminum chloride.

[0024] Furthermore, the cleaning temperature is 20~45℃, and the cleaning time is 10~150 s.

[0025] Furthermore, the cleaning solution used for cleaning comprises, by molar concentration meter: 0.05~2.0 mol / L aluminum salt, 0.1~3.5 mol / L sulfuric acid, and 0.1~2.2 mol / L nitric acid, with water as the solvent.

[0026] Furthermore, the aluminum salt in the cleaning solution is aluminum sulfate.

[0027] Furthermore, the average thickness of the phosphating film is 2~100 nm.

[0028] Furthermore, the post-processing temperature is 15~70℃, and the post-processing time is 35~350 s.

[0029] Furthermore, the post-processing is performed under the condition of applying direct current, wherein the current density of the direct current is 0.01~0.25 A / cm². 2 The voltage is 10~150 V.

[0030] Furthermore, the post-treatment solution is an aqueous solution of phosphoric acid and / or an aqueous solution of phosphate.

[0031] Furthermore, the concentration of the aqueous solution of phosphoric acid is 0.01~1.0 mol / L.

[0032] Furthermore, the concentration of the aqueous solution of the phosphate is 0.01~1.0 mol / L.

[0033] Furthermore, the phosphate is selected from any one or a combination of at least two of lithium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, and potassium dihydrogen phosphate.

[0034] Furthermore, the post-processing includes a drying step: wherein the drying temperature is 80~350℃ and the drying time is 3~300 s.

[0035] In a second aspect, the present invention provides an aluminum foil current collector, which is prepared by the method for preparing aluminum foil current collectors as described in the first aspect.

[0036] Furthermore, the tensile strength of the aluminum foil current collector is 150~210 MPa.

[0037] Furthermore, the elongation of the aluminum foil current collector is 1.5~4%.

[0038] Furthermore, the resistance of the aluminum foil current collector is 2~50 mΩ.

[0039] Thirdly, the present invention provides a positive electrode sheet, the positive electrode sheet comprising an aluminum foil current collector as described in the second aspect.

[0040] Fourthly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode as described in the third aspect.

[0041] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for preparing the aluminum foil current collector of the present invention is to prepare a rough surface by electrochemical etching of the pretreated battery-grade aluminum foil to balance the impact of electron migration generated by the internal electrochemical reaction of the lithium-ion battery on the interface between the current collector and the active material; at the same time, it reduces the burrs caused by needle puncture or external impact, and then improves the resistance value and stability by surface coating, thus preparing a high-safety etched aluminum foil current collector for lithium-ion batteries. (2) The method for preparing aluminum foil current collector described in this invention significantly improves the bonding strength between the current collector and the electrode material through the synergistic effect of the microporous structure formed by electrochemical etching and the surface coating, reduces the interface resistance, effectively suppresses the corrosion problem of aluminum foil at low potential, and avoids the lithium dendrite penetration phenomenon that is easy to occur in traditional current collectors under high current density, thus greatly improving the cycle life, safety performance and energy density of the battery. (3) The method for preparing aluminum foil current collector described in this invention is mainly for processing aluminum foil substrate with a purity of 99.7% or higher, achieving uniform etching of high-purity aluminum foil, while significantly ensuring the mechanical properties of high-purity aluminum foil current collector, such as tensile strength and elongation. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 The image shows a surface electron microscope image of the aluminum foil current collector prepared in Example 1.

[0044] Figure 2 This is a micro-electron microscope image of the safety thin film of the aluminum foil current collector prepared in Example 1. Detailed Implementation

[0045] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0047] In a first aspect, the present invention provides a method for preparing an aluminum foil current collector, the method comprising: The surface of the substrate aluminum foil with a purity of 99.7% or higher is pretreated until the dyne value of its surface is 64 dyne / cm or higher, and the pretreated substrate aluminum foil is obtained. The pretreated aluminum foil substrate is subjected to electrochemical etching to obtain the etched aluminum foil substrate. After cleaning the etched aluminum foil substrate, post-processing is performed until a phosphate film is formed on its surface to obtain the aluminum foil current collector.

[0048] It should be noted that, firstly, this invention targets high-purity aluminum foil substrates with a purity of 99.7% or higher. By controlling the dyne value to above 64 dyne / cm through surface pretreatment, a uniform reaction substrate is provided for subsequent electrochemical etching, successfully achieving precise and uniform etching of high-purity aluminum foil. Furthermore, the entire preparation process (pretreatment-etching-post-treatment) does not damage the microstructure of the aluminum foil substrate, effectively ensuring the core mechanical properties of the product, such as tensile strength and elongation, and solving the technical challenge of balancing uneven etching and mechanical properties in high-purity aluminum foil. Secondly, this invention first enhances the surface activity of the aluminum foil through pretreatment, and then constructs a controllable rough surface through electrochemical etching. This structure can balance the stress impact of electron migration during the internal electrochemical reaction of the lithium-ion battery on the interface between the current collector and the active material. Simultaneously, the etching process optimizes the surface morphology of the aluminum foil, reducing the risk of burrs caused by needle punctures or external impacts. The phosphate film further improves the resistivity and structural stability of the current collector, ultimately producing an etched aluminum foil current collector for lithium-ion batteries with active safety protection capabilities. Furthermore, the microporous structure formed by electrochemical etching increases the contact area between the current collector and the electrode material, creating a mechanical interlocking effect and significantly enhancing the interfacial bonding strength. Combined with the chemical stability and conductivity regulation function of the phosphate film, it not only effectively reduces interfacial resistance but also inhibits corrosion of the aluminum foil under low-potential conditions. Simultaneously, this composite structure acts as a physical barrier to prevent the growth and penetration of lithium dendrites under high current density. Through the synergistic effect of the microporous structure and the composite film, the cycle life, intrinsic safety performance, and energy density of the battery are comprehensively improved.

[0049] As an optional implementation, the purity of the substrate aluminum foil is 99.7% or higher, for example, it can be 99.70%, 99.72%, 99.74%, 99.76%, 99.78%, 99.80%, 99.82%, 99.84%, 99.86%, 99.88%, 99.90%, 99.92%, 99.94%, 99.96%, 99.98%, etc.

[0050] As an optional implementation, the thickness of the substrate aluminum foil is 12~19 μm, for example, it can be 12.0 μm, 12.5 μm, 13.0 μm, 13.5 μm, 14.0 μm, 14.5 μm, 15.0 μm, 15.5 μm, 16.0 μm, 16.5 μm, 17.0 μm, 17.5 μm, 18.0 μm, 18.5 μm, 19.0 μm, etc.

[0051] As an optional implementation, the copper content in the substrate aluminum foil is <500 ppm, for example, it can be 499 ppm, 450 ppm, 400 ppm, 350 ppm, 300 ppm, 250 ppm, 200 ppm, 150 ppm, 100 ppm, 50 ppm, 10 ppm, 1 ppm, etc.

[0052] As an optional implementation, the iron content in the substrate aluminum foil is <1500 ppm, for example, it can be 1500 ppm, 1400 ppm, 1300 ppm, 1200 ppm, 1100 ppm, 1000 ppm, 900 ppm, 800 ppm, 700 ppm, 600 ppm, 500 ppm, 400 ppm, 300 ppm, 200 ppm, 100 ppm, 50 ppm, 0 ppm, etc.

[0053] As an optional implementation, the dyne value of the surface of the pretreated aluminum foil substrate is 50 dyne / cm or higher, for example, it can be 50 dyne / cm, 51 dyne / cm, 52 dyne / cm, 53 dyne / cm, 54 dyne / cm, 55 dyne / cm, 56 dyne / cm, 57 dyne / cm, 58 dyne / cm, 59 dyne / cm, 60 dyne / cm, etc.

[0054] In a preferred embodiment, the dyne value of the surface of the pretreated aluminum foil substrate is 64 dyne / cm or higher, for example, it can be 64 dyne / cm, 65 dyne / cm, 66 dyne / cm, 67 dyne / cm, 68 dyne / cm, 69 dyne / cm, 70 dyne / cm, etc.

[0055] It should be noted that the dyne value of the surface of the substrate aluminum foil after the pretreatment is above 64 dyne / cm. The surface tension of the aluminum foil is matched with the surface tension of the etching solution, which can achieve complete spreading and uniform coverage of the etching solution on the surface of the high-purity aluminum foil. This avoids problems such as insufficient wettability, local accumulation of etching solution, and uneven etching reaction caused by the passivation film on the surface of high-purity aluminum. It ensures that the microporous structure grows uniformly throughout the aluminum foil surface during the etching process and eliminates local non-porous areas or over-etching.

[0056] As an optional implementation, the pretreatment method includes physical methods and / or chemical methods.

[0057] As an optional implementation, the physical method includes corona and / or plasma cleaning.

[0058] As an optional implementation, the chemical method includes acid leaching and / or alkali leaching.

[0059] As an optional implementation, the etched substrate aluminum foil has a uniformly rough surface with an average depth of 0.3~2.3 μm, for example, it can be 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, etc.

[0060] As an optional implementation, the electrochemical etching process is performed 1 to 3 times, for example, 1 time, 2 times, or 3 times.

[0061] As an optional implementation, the temperature of the electrochemical etching process is 36~47℃, for example, it can be 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, etc.

[0062] As an optional implementation, the AC current applied during the electrochemical etching process is 12~50 Hz, for example, it can be 12 Hz, 14 Hz, 16 Hz, 18 Hz, 20 Hz, 22 Hz, 24 Hz, 26 Hz, 28 Hz, 30 Hz, 32 Hz, 34 Hz, 36 Hz, 38 Hz, 40 Hz, 42 Hz, 44 Hz, 46 Hz, 48 Hz, 50 Hz, etc.

[0063] As an optional implementation, the current density of the electrochemical etching process is 0.05~0.5 A / cm. 2 For example, it could be 0.05 A / cm 2 0.1 A / cm 2 0.15 A / cm 2 0.2 A / cm 2 0.25, 0.3 A / cm 2 0.35, 0.4 A / cm 2 0.45, 0.5 A / cm 2 wait.

[0064] As an optional implementation, the electrochemical etching process is applied for 5 to 40 seconds, for example, 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, etc.

[0065] It should be noted that the parameters for the above electrochemical etching process are limited to adapt to the characteristics of high-purity aluminum foil and ensure etching quality and performance. Among them, the reaction rate is balanced at 36~47℃: if the temperature is too low, the etching will be slow and uneven, and if it is too high, the electrolyte will evaporate and the aluminum foil will be over-dissolved in some areas. The AC current of 12~50 Hz is matched with the current density of 0.05~0.5A / cm². The reaction area is controlled by alternating electric fields to avoid current concentration that may cause pitting corrosion. The energizing time of 5~40 s precisely controls the depth and density to prevent poor adhesion or degradation of mechanical properties and ensure the formation of a uniform and controllable rough surface.

[0066] As an optional implementation, the total acidity of the etching solution used in the electrochemical etching process is 2~3 N, for example, it can be 2.0 N, 2.1 N, 2.2 N, 2.3 N, 2.4 N, 2.5 N, 2.6 N, 2.7 N, 2.8 N, 2.9 N, 3.0 N, etc.

[0067] As an optional implementation, the etching solution comprises, by molar concentration meter: 1.9~2.9 mol / L hydrochloric acid, 0.01~0.3 mol / L sulfuric acid, 0.01~1 mol / L aluminum salt, and water as the solvent.

[0068] As an optional implementation, the concentration of hydrochloric acid in the etching solution is 1.9~2.9 mol / L, for example, it can be 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, etc.

[0069] As an optional implementation, the concentration of sulfuric acid in the etching solution is 0.01~0.3 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.10 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L, 0.20 mol / L, 0.22 mol / L, 0.24 mol / L, 0.26 mol / L, 0.28 mol / L, 0.30 mol / L, etc.

[0070] As an optional implementation, the concentration of aluminum salt in the etching solution is 0.01~1 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, etc.

[0071] It should be noted that the etching solution is adapted to the etching requirements of high-purity aluminum foil to achieve synergistic effects of the components. Among them, hydrochloric acid (1.9~2.9 mol / L) is the main etching agent, providing sufficient hydrogen ions and chloride ions to accelerate aluminum dissolution. If the concentration is too low, the etching will be slow and uneven, while if it is too high, it will easily lead to local over-corrosion. Sulfuric acid helps to refine micropores and inhibit surface roughening. Aluminum salt maintains the aluminum ion balance in the electrolyte, slows down the excessive reaction of the aluminum foil substrate, and stabilizes the etching rate. This ratio ensures the formation of a uniform and controllable rough surface and avoids defects.

[0072] As an optional implementation, the aluminum salt in the etching solution is aluminum chloride.

[0073] As an optional implementation, the cleaning temperature is 20~45℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 45℃, etc.

[0074] As an optional implementation, the cleaning time is 10~150 s, for example, it can be 10 s, 20 s, 40 s, 50 s, 60 s, 80 s, 100 s, 120 s, 140 s, 150 s, etc.

[0075] As an optional implementation, the cleaning solution used for cleaning comprises, by molar concentration meter: 0.05~2.0 mol / L aluminum salt, 0.1~3.5 mol / L sulfuric acid, 0.1~2.2 mol / L nitric acid, and water as the solvent.

[0076] As an optional implementation, the concentration of aluminum salt in the cleaning solution is 0.05~2.0 mol / L, for example, it can be 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, etc.

[0077] As an optional implementation, the concentration of sulfuric acid in the cleaning solution is 0.1~3.5 mol / L, for example, it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1.1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 2.1 mol / L, 2.3 mol / L, 2.5 mol / L, 2.7 mol / L, 2.9 mol / L, 3.1 mol / L, 3.3 mol / L, 3.5 mol / L, etc.

[0078] As an optional implementation, the concentration of aluminum salt in the cleaning solution is 0.01~1 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, etc.

[0079] It should be noted that the cleaning solution is designed to meet the cleaning requirements of high-purity aluminum foil after etching, achieving a synergistic effect of "decontamination-structure protection-film formation". Sulfuric acid (0.1~3.5 mol / L) dissolves residual chlorides, aluminum salts, and other products from the etching process, preventing blockage of micropores. Nitric acid (0.1~2.2 mol / L) passivates the aluminum substrate through weak oxidation, preventing excessive corrosion during cleaning and removing surface impurities. Aluminum salts (0.05~2.0 mol / L) maintain the aluminum ion balance in the solution, inhibiting aluminum foil dissolution and protecting the etched microporous structure. The appropriate concentrations ensure a clean, residue-free surface without damaging the existing rough morphology, providing a clean and active substrate for the subsequent uniform formation of the phosphating film.

[0080] As an optional implementation, the aluminum salt in the cleaning solution is aluminum sulfate.

[0081] As an optional implementation, the average thickness of the phosphating film is 2~100 nm, for example, it can be 2 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.

[0082] As an optional implementation, the post-processing temperature is 15~70℃, for example, it can be 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, etc.

[0083] As an optional implementation, the post-processing time is 35~350 s, for example, it can be 35 s, 70 s, 105 s, 140 s, 175 s, 210 s, 245 s, 280 s, 315 s, 350 s, etc.

[0084] As an optional implementation, the post-processing is performed under conditions of applied direct current.

[0085] As an optional implementation, the post-treatment solution is an aqueous solution of phosphoric acid and / or an aqueous solution of phosphate.

[0086] It should be noted that the post-processing utilizes an aqueous solution of phosphoric acid and / or an aqueous solution of phosphate, supplemented by the synergistic effect of direct current, to achieve controllable and high-performance phosphating film formation. The direct current provides a directional electric field for film formation, causing the aluminum foil to act as the anode and undergo an oxidation reaction to generate aluminum ions. Simultaneously, it guides phosphate ions in the electrolyte to migrate directionally to the aluminum foil surface, reacting precisely with the aluminum ions to generate aluminum phosphate, thus avoiding the problems of loose film layers and poor adhesion formed by spontaneous reactions later on. Furthermore, the phosphoric acid / phosphate aqueous solution provides a stable phosphate ion source for film formation, and the solution system allows for controllable film growth rate, ensuring uniform film coverage inside and outside the etched micropores.

[0087] As an optional implementation, the current density of the direct current is 0.01~0.25 A / cm². 2 For example, it could be 0.01 A / cm 2 0.02 A / cm 2 0.03 A / cm 2 0.04 A / cm 2 0.05 A / cm 2 0.06 A / cm 2 0.07 A / cm 2 0.08 A / cm 2 0.09 A / cm 2 0.1 A / cm 2 0.12 A / cm 2 0.14 A / cm 2 0.16 A / cm 2 0.18 A / cm 2 0.2A / cm 2 0.22 A / cm 2 0.24 A / cm 2 0.25 A / cm 2 wait.

[0088] As an optional implementation, the voltage of the DC power supply is 10~150 V, for example, it can be 10 V, 11 V, 12 V, 13 V, 14 V, 15 V, 16 V, 17 V, 18 V, 19 V, 20 V, 40 V, 50 V, 60 V, 80 V, 100 V, 120 V, 140 V, 150 V, etc.

[0089] It should be noted that the current density and voltage conditions of the post-treatment can promote film densification, improve corrosion resistance and structural stability, while avoiding damage to the microporous structure formed by etching. This ensures the interfacial compatibility between the film and the aluminum foil substrate and subsequent electrode materials, ultimately achieving synergistic optimization of current collector safety and electrochemical performance. Current density: 0.01~0.25 A / cm² 2 The film formation rate can be adjusted. If it is too low, the film will be thin and not dense. If it is too high, it will easily cause violent local reactions, and the film will crack and fall off. The voltage of 10~150 V provides a suitable electric field strength to ensure the directional migration reaction of aluminum ions and phosphate ions, avoid insufficient film formation due to insufficient voltage or excessive oxidation caused by excessive voltage, and protect the etched micropore structure from damage.

[0090] As an optional implementation, the concentration of the aqueous solution of phosphoric acid is 0.01~1.0 mol / L, for example, it can be 0.01 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc.

[0091] As an optional implementation, the concentration of the phosphate aqueous solution is 0.01~1.0 mol / L, for example, it can be 0.01 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc.

[0092] As an optional implementation, the phosphate is selected from any one or a combination of at least two of lithium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, and potassium dihydrogen phosphate.

[0093] As an optional implementation, the post-processing may further include a drying step.

[0094] As an optional implementation, the drying temperature is 80~350℃, for example, it can be 80℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 350℃, etc.

[0095] As an optional implementation, the drying time is 3 to 300 s, for example, it can be 3 s, 6 s, 9 s, 12 s, 15 s, 18 s, 21 s, 24 s, 27 s, 30 s, 33 s, 36 s, 39 s, 42 s, 45 s, 48 ​​s, 51 s, 54 s, 57 s, 60 s, 90 s, 120 s, 150 s, 180 s, 210 s, 240 s, 270 s, 300 s, etc.

[0096] In a second aspect, the present invention provides an aluminum foil current collector, which is prepared by the method for preparing aluminum foil current collectors as described in the first aspect.

[0097] As an optional implementation, the tensile strength of the aluminum foil current collector is 150~210 MPa, for example, it can be 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, 210 MPa, etc.

[0098] As an optional implementation, the elongation of the aluminum foil current collector is 1.5% to 4%, for example, it can be 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, etc.

[0099] As an optional implementation, the resistance of the aluminum foil current collector is 2~50 mΩ, for example, it can be 2 mΩ, 4 mΩ, 8 mΩ, 10 mΩ, 15 mΩ, 20 mΩ, 25 mΩ, 30 mΩ, 35 mΩ, 40 mΩ, 45 mΩ, 50 mΩ, etc.

[0100] Thirdly, the present invention provides a positive electrode sheet, the positive electrode sheet comprising an aluminum foil current collector as described in the second aspect.

[0101] Fourthly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode as described in the third aspect.

[0102] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0103] Example 1 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries, the preparation method specifically including the following steps: (1) The surface of the high-purity substrate aluminum foil is subjected to corona treatment until the dyne value of its surface is 64 dyne / cm, and the pretreated substrate aluminum foil is obtained. The high-purity aluminum foil substrate has a thickness of 15 μm, a purity of 99.80%, and a copper content of 50 ppm and an iron content of 900 ppm; the corona power is 20 kW and the speed is 20 m / min. (2) The pretreated aluminum foil obtained in step (1) is placed in an etching solution, and an alternating current is applied to perform electrochemical etching to obtain an etched aluminum foil with a uniform rough surface of an average depth of 1.0 μm. The electrochemical etching process was performed twice, at a temperature of 42°C, with an AC current applied at a frequency of 30 Hz and a current density of 0.2 A / cm². 2 The power-on time is 20 s; the total acidity of the etching solution is 2.5 N, and the etching solution comprises, by molar concentration meter: 2.4 mol / L hydrochloric acid, 0.2 mol / L sulfuric acid, 0.5 mol / L aluminum chloride, and water as the solvent; (3) Place the etched substrate aluminum foil obtained in step (2) in the cleaning solution and clean it to obtain the cleaned substrate aluminum foil; The cleaning temperature is 20°C, and the cleaning time is 150 seconds. The cleaning solution, measured by molar concentration meter, comprises: 1.0 mol / L aluminum sulfate, 1.8 mol / L sulfuric acid, and 1.2 mol / L nitric acid, with water as the solvent. (4) The cleaned substrate aluminum foil obtained in step (3) is placed in a phosphoric acid solution, a direct current is applied, and post-treatment is performed to obtain an aluminum foil with an average thickness of 10 nm. The post-processing temperature is 70°C, and the post-processing time is 120 s; the DC current density is 0.05 A / cm². 2 The voltage is 9 V; the phosphoric acid solution is an aqueous solution of phosphoric acid with a concentration of 0.5 mol / L; (5) The aluminum foil with phosphating film obtained in step (4) is placed at 350°C for 30 s to dry, and the high-safety lithium-ion battery etched aluminum foil current collector is obtained.

[0104] Figure 1 This is a surface electron microscope image of the aluminum foil current collector prepared in Example 1. Figure 1 As shown, the electrochemically etched aluminum foil forms a sponge-like corrosion morphology. This sponge layer possesses a three-dimensional interconnected porous network structure with abundant pores and a wide pore size distribution, significantly increasing the effective surface area of ​​the aluminum foil. The pores are interconnected, forming open ion transport channels, allowing the electrolyte to quickly penetrate into the deep structure, thereby reducing ion diffusion resistance and improving frequency response characteristics and charge / discharge efficiency. Figure 2 This is a micro-electron microscopy image of the safety thin film of the aluminum foil current collector prepared in Example 1. Figure 2As shown, an alumina-alumina phosphate film was formed on the surface of the aluminum foil sponge layer by electrochemical etching. It is extremely thin and is mainly composed of barrier alumina and aluminum phosphate. It is dense, uniform, and has strong electronic insulation properties. It adheres tightly to the aluminum substrate and is firmly bonded to the metal interface, just like "rooted in the soil", effectively preventing electron penetration.

[0105] Example 2 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries, the preparation method specifically including the following steps: (1) The surface of the high-purity substrate aluminum foil is subjected to plasma cleaning until the dyne value of its surface is 64 dyne / cm, and the pretreated substrate aluminum foil is obtained. The high-purity aluminum foil substrate has a thickness of 12 μm, a purity of 99.70%, and a copper content of 50 ppm and an iron content of 1200 ppm. The plasma cleaning process includes: introducing Ar2 into a vacuum chamber and controlling the flow rate to maintain a vacuum chamber pressure of 5 Pa; once the Ar2 flow rate stabilizes at 200 sccm, turning on the bias power supply and adjusting the power to 150 W; generating plasma through glow discharge to clean the aluminum foil surface; and turning off the bias power supply after 10 minutes of cleaning. (2) The pretreated aluminum foil obtained in step (1) is placed in an etching solution, an alternating current is applied, and an electrochemical etching process is performed to obtain an etched aluminum foil with a uniform rough surface of an average depth of 0.3 μm. The electrochemical etching process was performed three times at a temperature of 36°C, with an AC current applied at a frequency of 20 Hz and a current density of 0.1 A / cm². 2 The power-on time is 10 s; the total acidity of the etching solution is 2 N, and the etching solution comprises, by molar concentration meter: 1.9 mol / L hydrochloric acid, 0.01 mol / L sulfuric acid, 0.01 mol / L aluminum chloride, and water as the solvent; (3) Place the etched substrate aluminum foil obtained in step (2) in the cleaning solution and clean it to obtain the cleaned substrate aluminum foil; The cleaning temperature is 25°C, and the cleaning time is 500 seconds. The cleaning solution, measured by molar concentration meter, comprises: 0.5 mol / L aluminum sulfate, 2.5 mol / L sulfuric acid, and 0.5 mol / L nitric acid, with water as the solvent. (4) The cleaned substrate aluminum foil obtained in step (3) is placed in a phosphoric acid solution, a direct current is applied, and post-processing is performed to obtain an aluminum foil current collector with an average thickness of 50 nm. The post-processing temperature is 60°C, the post-processing time is 200 s, and the DC current density is 0.01 A / cm². 2 The voltage is 40 V; the phosphoric acid solution is an aqueous solution of sodium dihydrogen phosphate with a concentration of 0.2 mol / L; (5) The aluminum foil with phosphating film obtained in step (4) is placed at 350°C for 30 s to dry, and the high-safety lithium-ion battery etched aluminum foil current collector is obtained.

[0106] Example 3 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries, the preparation method specifically including the following steps: (1) The surface of the high-purity substrate aluminum foil is acid-etched and cleaned until the dyne value of its surface is 64 dyne / cm, and the pretreated substrate aluminum foil is obtained. The high-purity aluminum foil substrate has a thickness of 19 μm, a purity of 99.90%, and a copper content of 50 ppm and an iron content of 300 ppm. The acid leaching reagent is 0.1 mol / L phosphoric acid, the acid leaching temperature is 65℃, and the acid leaching time is 2 min. (2) The pretreated aluminum foil obtained in step (1) is placed in an etching solution, an alternating current is applied, and an electrochemical etching process is performed to obtain an etched aluminum foil with a uniform rough surface of an average depth of 2.3 μm. The electrochemical etching process was performed twice, at a temperature of 47°C, with an AC current applied at a frequency of 40 Hz and a current density of 0.3 A / cm². 2 The power-on time is 30 s; the total acidity of the etching solution is 3 N, and the etching solution comprises, by molar concentration meter: 2.9 mol / L hydrochloric acid, 0.3 mol / L sulfuric acid, 1 mol / L aluminum chloride, and water as the solvent; (3) Place the etched substrate aluminum foil obtained in step (2) in the cleaning solution and clean it to obtain the cleaned substrate aluminum foil; The cleaning temperature is 30℃, and the cleaning time is 400 s; the cleaning solution comprises, by molar concentration meter: 2 mol / L aluminum sulfate, 3.5 mol / L sulfuric acid, 2.2 mol / L nitric acid, and water as the solvent; (4) The cleaned substrate aluminum foil obtained in step (3) is placed in a phosphoric acid solution, a direct current is applied, and post-processing is performed to obtain an aluminum foil current collector with an average thickness of 100 nm. The post-processing temperature is 50°C, the post-processing time is 350 s, and the DC current density is 0.1 A / cm².2 The voltage is 90 V; the phosphoric acid solution is an aqueous solution of ammonium dihydrogen phosphate with a concentration of 1.0 mol / L; (5) The aluminum foil with phosphating film obtained in step (4) is dried at 350°C for 30 s to obtain the high-safety lithium-ion battery etched aluminum foil current collector.

[0107] Example 4 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries. The only difference from Embodiment 1 is that in step (2), the electrochemical etching process is performed once, the temperature is 50°C, the AC current is applied at a frequency of 20 Hz, and the current density is 0.01 A / cm². 2 The power-on time is 60 seconds; other steps are the same as in Example 1.

[0108] Example 5 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries. The only difference from Embodiment 1 is that in step (2), the etching solution no longer contains sulfuric acid, and the concentration of hydrochloric acid is increased to 2.8 mol / L; the other steps are the same as in Embodiment 1.

[0109] Example 6 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries. The only difference from Embodiment 1 is that in step (3), the cleaning solution is replaced with pure water and the cleaning time is extended to 900 s; the other steps are the same as in Embodiment 1.

[0110] Example 7 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries. The only difference from Embodiment 1 is that in step (4), the post-treatment temperature is 20°C, the post-treatment time is 360 s, and the DC current density is 0.2 A / cm². 2 The voltage is 10 V; other steps are the same as in Example 1.

[0111] Example 8 This embodiment provides a method for preparing an etched aluminum foil current collector for high-safety lithium-ion batteries. The only difference from Embodiment 1 is that in step (4), direct current is no longer applied, but the aluminum foil is immersed in an aqueous solution of phosphoric acid for impregnation treatment, and the post-treatment time is extended to 360 s; the other steps are the same as in Embodiment 1.

[0112] Comparative Example 1 This comparative example provides a method for preparing an aluminum foil current collector. The only difference from Example 1 is that the pretreatment step (1) is not performed, while the other steps are the same as in Example 1.

[0113] Comparative Example 2 This comparative example provides a method for preparing an aluminum foil current collector. The only difference from Example 1 is that in step (1), the surface dyne value is only 40 dyne / cm after pretreatment. The other steps are the same as in Example 1.

[0114] Comparative Example 3 This comparative example provides a method for preparing an aluminum foil current collector. The only difference from Example 1 is that the cleaning process in step (3) is not performed, while the other steps are the same as in Example 1.

[0115] Comparative Example 4 This comparative example provides a method for preparing an aluminum foil current collector. The only difference from Example 1 is that the post-processing step (4) is not performed, while the other steps are the same as in Example 1.

[0116] Test Example 1 Test samples: Aluminum foil current collectors provided in Examples 1-8 and aluminum foil current collectors provided in Comparative Examples 1-4.

[0117] Test method: (1) Tensile strength: The aluminum foil current collectors obtained in Examples 1-8 and Comparative Examples 1-4 were cut into 150mm pieces using a pneumatic die. The 15 mm sample was tested according to GB / T 22638.11 Aluminum Foil Test Methods Part 11: Test Methods for Mechanical Properties.

[0118] (2) Elongation: The aluminum foil current collectors obtained in Examples 1-8 and Comparative Examples 1-4 were cut into 150mm pieces using a pneumatic die. The 15 mm sample was tested according to GB / T 22638.11 Aluminum Foil Test Methods Part 11: Test Methods for Mechanical Properties.

[0119] (3) Resistance: The aluminum foil current collectors obtained in Examples 1-8 and Comparative Examples 1-4 were used to determine the room temperature resistance according to GB / T 22638.6.

[0120] The specific test results are shown in Table 1 below (where "before treatment" refers to the high-purity aluminum foil substrate that has not undergone pretreatment in each example, and "after treatment" refers to the final aluminum foil current collector): Table 1

[0121] As shown in Table 1, the tensile strength of the aluminum foil current collector is 150~210 MPa, the elongation is 1.5~4%, and the resistivity is 2~50 mΩ. This fully demonstrates that the preparation method of the aluminum foil current collector of the present invention involves preparing a rough surface by electrochemical etching of pre-treated battery-grade aluminum foil to balance the impact of electron migration generated by the internal electrochemical reaction of the lithium-ion battery on the interface between the current collector and the active material; reducing burrs caused by needle punctures or external impacts; and then improving the resistivity through surface coating. Furthermore, the preparation method of the aluminum foil current collector of the present invention mainly targets the treatment of substrate aluminum foil with a purity of 99.7% or higher, achieving uniform etching of high-purity aluminum foil while significantly ensuring the mechanical properties of the high-purity aluminum foil current collector, such as tensile strength and elongation.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an aluminum foil current collector, characterized in that, The method for preparing the aluminum foil current collector includes: The surface of the substrate aluminum foil with a purity of 99.7% or higher is pretreated until the dyne value of its surface is 64 dyne / cm or higher, and the pretreated substrate aluminum foil is obtained. The pretreated aluminum foil substrate is subjected to electrochemical etching to obtain the etched aluminum foil substrate. After cleaning the etched aluminum foil substrate, post-processing is performed until a phosphate film is formed on its surface to obtain the aluminum foil current collector.

2. The method for preparing the aluminum foil current collector according to claim 1, characterized in that, The thickness of the substrate aluminum foil is 12~19 μm; Preferably, the copper content in the aluminum foil substrate is <500 ppm; Preferably, the iron content in the aluminum foil substrate is <1500 ppm; Preferably, the pretreatment method includes physical methods and / or chemical methods; Preferably, the physical method includes corona and / or plasma cleaning; Preferably, the chemical method includes acid leaching and / or alkali leaching.

3. The method for preparing the aluminum foil current collector according to claim 1, characterized in that, The etched substrate aluminum foil has a uniformly rough surface with an average depth of 0.3~2.3 μm; Preferably, the electrochemical etching process is performed 1 to 3 times; Preferably, the temperature of the electrochemical etching process is 36~47℃; Preferably, the alternating current applied during the electrochemical etching process has a frequency of 12-50 Hz and a current density of 0.05-0.5 A / cm². 2 The power-on time is 5~40 s; Preferably, the total acidity of the etching solution used in the electrochemical etching process is 2~3 N; Preferably, the etching solution comprises, by molar concentration meter: 1.9~2.9 mol / L hydrochloric acid, 0.01~0.3 mol / L sulfuric acid, 0.01~1 mol / L aluminum salt, and water as the solvent; Preferably, the aluminum salt in the etching solution is aluminum chloride.

4. The method for preparing the aluminum foil current collector according to claim 1, characterized in that, The cleaning temperature is 20~45℃, and the cleaning time is 10~150 s; Preferably, the cleaning solution used for cleaning comprises, by molar concentration meter: 0.05~2.0 mol / L aluminum salt, 0.1~3.5 mol / L sulfuric acid, and 0.1~2.2 mol / L nitric acid, with water as the solvent; Preferably, the aluminum salt in the cleaning solution is aluminum sulfate.

5. The method for preparing the aluminum foil current collector according to claim 1, characterized in that, The average thickness of the phosphating film is 2~100 nm; Preferably, the post-processing temperature is 15~70℃, and the post-processing time is 35~350 s; Preferably, the post-processing is performed under a direct current applied, wherein the current density of the direct current is 0.01~0.25 A / cm². 2 The voltage is 10~150 V; Preferably, the solution used in the post-treatment is an aqueous solution of phosphoric acid and / or an aqueous solution of phosphate; Preferably, the concentration of the aqueous solution of phosphoric acid is 0.01~1.0 mol / L; Preferably, the concentration of the aqueous solution of the phosphate is 0.01~1.0 mol / L; Preferably, the phosphate is selected from any one or a combination of at least two of lithium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, and potassium dihydrogen phosphate; Preferably, the post-processing further includes a drying step: wherein the drying temperature is 80~350℃ and the drying time is 3~300 s.

6. An aluminum foil current collector, characterized in that, The aluminum foil current collector is prepared by the method for preparing aluminum foil current collectors as described in any one of claims 1 to 5.

7. The aluminum foil current collector according to claim 6, characterized in that, The tensile strength of the aluminum foil current collector is 150~210 MPa, and the elongation of the aluminum foil current collector is 1.5~4%.

8. The aluminum foil current collector according to claim 6, characterized in that, The resistance of the aluminum foil current collector is 2~50 mΩ.

9. A positive electrode sheet, characterized in that, The positive electrode sheet includes an aluminum foil current collector as described in any one of claims 6 to 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the positive electrode as described in claim 9.

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