Copper foil and its preparation methods, lithium battery copper foil, current collectors, electrodes, batteries and electrical devices

Abstract

This invention relates to a copper foil and its preparation method, lithium-ion battery copper foil, current collector, electrode, battery, and electrical device. The transverse tensile strength of this copper foil at room temperature is defined as S0, in kgf / mm². 2 The transverse elongation is E0. The transverse tensile strength of the copper foil after baking at 200℃ for 1 hour is S1, in kgf / mm². 2 The lateral elongation is E1, and the tensile strength decay rate is R1. S0, E0, S1, E1, and R1 satisfy: R1 = (1 - S1 / S0) * 100% < 10%, and E1 - E0 > 0. This copper foil exhibits excellent thermal stability, reducing breakage and wrinkling during manufacturing and battery production and use. Its application in lithium-ion battery copper foil can improve battery cycle life and safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a copper foil and a preparation method thereof, a lithium battery copper foil, a current collector, a pole piece, a battery and an electric device. BACKGROUND

[0002] As a green and environmentally friendly energy storage device, lithium batteries have the advantages of high energy density, excellent cycle performance, high safety, etc., and have become the key support for electronic devices, electric tools, large-scale energy storage, new energy vehicles and other industries, and are an important basic technology to achieve the "double carbon" goal.

[0003] Among the many components of lithium batteries, the current collector serves as a carrier for active materials, plays an important role in collecting the current generated by active materials and outputting greater current, and is a key auxiliary material for high-energy-density lithium batteries. The high electrical conductivity, moderate potential, soft texture, stable properties and low price of electrolytic copper foil determine that it is the best choice for lithium battery negative current collector. As one of the important components of lithium batteries, the performance of lithium battery copper foil is also a key factor affecting the performance of lithium batteries. Therefore, it is crucial to prepare high-performance lithium battery copper foil to improve the electrochemical performance of lithium batteries. In addition, the expansion and contraction of silicon negative electrode material during lithium extraction (up to more than 300%) and the thermal effect generated by fast charging technology of solid-state batteries have higher requirements for the thermal stability of the mechanical properties of copper foil materials at high temperatures. The traditional lithium battery copper foil has the defect of insufficient thermal stability and needs to be improved. SUMMARY

[0004] Based on this, the present application provides a copper foil and a preparation method thereof, a lithium battery copper foil, a current collector, a pole piece, a battery and an electric device. The copper foil has excellent thermal stability and can be used as a lithium battery copper foil to improve the performance of the battery.

[0005] The technical scheme is as follows:

[0006] A copper foil, wherein the transverse tensile strength of the copper foil is S0, unit: kgf / mm 2 , the transverse elongation is E0, the transverse tensile strength of the copper foil after being baked at 200℃ for 1h is S1, unit: kgf / mm 2 , the transverse elongation is E1, the tensile strength decay rate is R1, and the S0, E0, S1, E1 and R1 satisfy:

[0007] R1 = (1-S1 / S0)*100% <10%, and E1-E0>0.

[0008] In one embodiment, the transverse tensile strength of the copper foil after being baked at 200℃ for 2h is S2, unit: kgf / mm2 , the transverse elongation rate is E2, and the tensile strength attenuation rate is R2, the S0, E0, S2, E2 and R2 satisfy:

[0009] R2 = (1 - S2 / S0) * 100% < 20%, and E2 - E0 > 0.

[0010] In one embodiment, the transverse tensile strength of the copper foil after baking treatment for 3h at 200℃ is S3, and the unit is kgf / mm 2 , the transverse elongation rate is E3, and the tensile strength attenuation rate is R3, the S0, E0, S3, E3 and R3 satisfy:

[0011] R3 = (1 - S3 / S0) * 100% < 30%, and E3 - E0 > 0.

[0012] In one embodiment, the transverse tensile strength of the copper foil at room temperature is 40kgf / mm 2 ~ 90kgf / mm 2 .

[0013] In one embodiment, the transverse elongation rate of the copper foil at room temperature is 3% or more.

[0014] In one embodiment, the difference between the longitudinal tensile strength and the transverse tensile strength of the copper foil is 1kgf / mm 2 or less.

[0015] In one embodiment, the copper foil includes 90% or more of grains with a particle size of less than 0.6μm at room temperature, in terms of percentage of the total number of grains in the copper foil.

[0016] In one embodiment, the copper foil includes 90% or more of grains with a particle size of less than 0.6μm after baking treatment for 1h at 200℃, in terms of percentage of the total number of grains in the copper foil.

[0017] In one embodiment, the copper foil has opposite first and second surfaces, the glossiness of the first surface is Gs1, the glossiness of the second surface is Gs2, Gs1 > Gs2, and the average grain difference between the first surface and the second surface satisfies:

[0018] and the average grain difference is less than 0.2μm;

[0019] wherein, d1 represents the size of a single grain on the first surface, in units of μm, n d1N(d1) represents the number of grains with size d1 in the first surface, d2 represents the size of a single grain in the second surface, in units of μm, and n d2 N(d2) represents the number of grains with size d2 in the second surface.

[0020] In one embodiment, the thickness of the copper foil is 3 μm to 12 μm.

[0021] The application also provides a method for preparing the copper foil as described above, and the technical solution is as follows:

[0022] A method for preparing the copper foil as described above, wherein the copper foil is prepared by an electrolysis method.

[0023] The electrolyte used in the electrolysis method comprises the following components:

[0024] Copper ions 90 g / L ± 2 g / L, sulfuric acid 105 g / L ± 5 g / L, chloride ions 23 ppm ± 2 ppm, brightener 40 mg / L ± 20 mg / L, leveling agent 12 mg / L ± 8 mg / L, and walking agent 12 mg / L ± 8 mg / L.

[0025] The brightener comprises a sulfur-containing group compound, the leveling agent comprises a nitrogen-containing amine organic matter, and the walking agent comprises a plurality of polyether compounds, and at least includes polyethylene glycol.

[0026] In one embodiment, the sulfur-containing group compound comprises one or more of polydithiodipropyl sulfone sodium, alcohol sulfur group propane sulfone sodium, 3-mercapto-1-propane sulfonic acid sodium, and piperazine dithioformic acid propane sulfonic acid sodium.

[0027] In one embodiment, the nitrogen-containing amine organic matter comprises one or more of polyethylene imine alkyl compound and collagen.

[0028] In one embodiment, the walking agent is compounded from a first polyether compound and a second polyether compound according to a concentration ratio of (1-2):1, wherein the first polyether compound is polyethylene glycol, and the second polyether compound comprises one or more of octylphenol polyoxyethylene ether and oxirane propylene oxide block polyether compound.

[0029] In one embodiment, the temperature of the electrolyte is 52℃ ± 3℃.

[0030] In one embodiment, the current applied during the electrolysis method is 25000 A ± 5000 A.

[0031] The application also provides the use of the copper foil as described above, and the technical solution is as follows:

[0032] A lithium battery copper foil, comprising the copper foil as described above or prepared according to the preparation method of the copper foil as described above.

[0033] A current collector, comprising the lithium battery copper foil as described above.

[0034] A pole piece, comprising the current collector as described above.

[0035] A battery, comprising the pole piece as described above.

[0036] An electric device, comprising the battery as described above.

[0037] The present application has at least the following beneficial effects:

[0038] Tensile strength and elongation are important performance indicators of copper foil, and high tensile strength and high elongation copper foil with excellent thermal stability has strong resistance to external force such as rolling and winding of lithium battery negative pole piece and stronger high temperature resistance in the charging and discharging process, avoiding the phenomenon of capacity decline caused by copper foil fracture; effectively enhance the binding energy of the negative material that deforms during the charging and discharging process of lithium ion battery, and improve the cycle stability of the battery. The copper foil provided by the present application has a transverse tensile strength decay rate R1=(1-S1 / S0)*100%<10% after baking at 200℃ for 1h, and the elongation is larger than that at room temperature initial state, which indicates that it has excellent thermal stability and can still maintain excellent mechanical properties after high temperature baking, thereby reducing the occurrence of copper foil fracture and wrinkling in the manufacturing process and the manufacturing and use process of the battery. When used for lithium battery copper foil, it can improve the cycle and safety of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 EBSD photos of the thickness roller surface and the deposition surface of the copper foil prepared by using Example 1, wherein Figure 1 (a) is the EBSD photo of the roller surface, Figure 1 (b) is the EBSD photo of the deposition surface;

[0040] Figure 2 EBSD photos of the thickness roller surface and the deposition surface of the copper foil prepared by using Comparative Example 1, wherein Figure 2 (a) is the EBSD photo of the roller surface, Figure 2 (b) is the EBSD photo of the deposition surface. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present application, the present application will be described more fully below, and the preferred embodiments of the present application are given. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] In the case using "comprise", "have", and "include" in the description herein, it is intended to cover the inclusive not exclusive inclusion, unless the explicit limiting term is used, such as "only", "consisting of", etc., another component can be added.

[0044] The words "preferably", "more preferably", "most preferably", "particularly", "more particularly", "particularly preferably", "most particularly" and the like used in the specification and claims are used to describe embodiments that are particularly advantageous. Such words are not used to limit the present application in any way but to emphasize alternative embodiments. For example, an element described as "preferably" is an option and can be used or not used. An element described as "more preferably" is optional but if used is used in preference. An element described as "particularly preferably" or "most particularly preferably" is optional but if used is used in preference to all other alternatives. None of the terms, preferably, more preferably, particularly, most particularly or particularly preferably preclude the use of a combination of alternatives.

[0045] In the present application, "further", "furthermore", "in particular" and the like are used to describe purposes of description, and should not be understood as limiting the scope of protection of the present application.

[0046] In the present application, "at least one" means one or more, such as one, two, and more than two. "Multiple" or "several" means at least two, such as two, three, etc. "Multiple layers" means at least two layers, such as two, three, etc., unless otherwise explicitly specified. In the description of the present application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0047] When a numerical range is disclosed herein, the range is to be construed as continuous, and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when ranges are provided for a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood as encompassing any and all sub-ranges subsumed therein.

[0048] Unless otherwise specified, all steps of this invention may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0049] Unless otherwise stated, a singular term may include a plural term and should not be understood as having a quantity of one.

[0050] In this invention, "above" or "below" both include the number itself. For example, "below 1" includes 1.

[0051] In this invention, room temperature refers to 0℃ to 40℃, including but not limited to 10℃ to 40℃, or further to 20℃ to 30℃.

[0052] Fast charging technology is an important development direction for power batteries. High-rate fast charging generates a large amount of heat, causing the battery's internal temperature to rise rapidly. Simultaneously, the shrinkage and expansion of the negative electrode active material increases significantly, placing more stringent requirements on the current collector to maintain good mechanical properties at high temperatures. Tensile strength and elongation are crucial performance indicators for copper foil. Low tensile strength and elongation can easily lead to breakage and wrinkling during the manufacturing process and cell fabrication, significantly impacting production efficiency and battery performance. Furthermore, copper foil with excellent thermal stability, high tensile strength, and high elongation exhibits stronger resistance to external forces such as rolling and winding of lithium-ion battery negative electrode sheets and greater high-temperature resistance during charge and discharge, preventing copper foil breakage and capacity reduction. It also effectively enhances the binding energy with the negative electrode material that deforms during lithium-ion battery charge and discharge, improving battery cycle stability. However, traditional lithium-ion battery copper foil current collectors suffer from insufficient thermal stability, requiring urgent improvement.

[0053] Based on this, the present invention provides a copper foil with excellent thermal stability, which can be used as a lithium battery copper foil to improve battery performance.

[0054] The technical solution is as follows:

[0055] A copper foil, wherein the transverse tensile strength of the copper foil under room temperature conditions (e.g., 10℃~40℃, further 25℃) is S0, in kgf / mm². 2 The transverse elongation is E0. The transverse tensile strength of the copper foil after baking at 200℃ for 1 hour is S1, with units of kgf / mm².2 The lateral elongation is E1, the tensile strength attenuation rate is R1, and S0, E0, S1, E1, and R1 satisfy:

[0056] R1 = (1 - S1 / S0) * 100% < 10%, and E1 - E0 > 0.

[0057] The poor thermal stability of copper foil can be divided into two situations: (1) After high-temperature baking, the tensile strength is severely reduced, resulting in a decrease in yield strength ratio. The copper foil has poor thermal stability. Under the high temperature conditions of battery charging, especially fast charging, the copper foil is prone to breakage, affecting the safety and cycle performance of the battery; (2) After high-temperature baking, the elongation rate is severely reduced, which also leads to a decrease in yield strength. Under the charging conditions, the copper foil is prone to wrinkling, leading to a short circuit in the battery. In this invention, after the copper foil is baked at 200°C for 1 hour, its tensile strength decreases little, and the tensile strength decrease rate R1 = (1-S1 / S0)*100% < 10% (including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9%. Further, R1 < 8%. Even further, R1 < 6%), while the elongation increases. This indicates that it has excellent thermal stability and can still maintain excellent mechanical properties after high-temperature baking, thereby reducing the occurrence of breakage and wrinkling of the copper foil during manufacturing and battery manufacturing and use. Using it as lithium battery copper foil can improve the cycle life and safety of the battery.

[0058] Understandably, this invention does not impose any special limitations on the testing methods for the tensile strength and elongation of copper foil; conventional testing methods in the art can be used. Optionally, in the embodiments of this invention, the tensile strength and elongation of the samples are tested using a HY-0230 universal testing machine manufactured by Shanghai Hengyi Precision Instruments Co., Ltd., according to the testing methods of GB / T29847-2013, at room temperature and a strain rate of 50 mm / min.

[0059] In one embodiment, the transverse tensile strength of the copper foil after baking at 200°C for 2 hours is defined as S2, in kgf / mm². 2 The lateral elongation is E2, the tensile strength attenuation rate is R2, and S0, E0, S2, E2, and R2 satisfy:

[0060] R2 = (1 - S2 / S0) * 100% < 20%, and E2 - E0 > 0.

[0061] After baking at 200℃ for 2 hours, the copper foil exhibits a tensile strength attenuation rate R2 = (1 - S2 / S0) * 100% < 20% (including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or 19%. Further, R2 < 15%. Even further, R2 < 10%. Still further, R2 < 8%.), and an elongation greater than the initial value. This indicates that the copper foil still possesses excellent thermal stability and maintains excellent mechanical properties after high-temperature baking, thereby reducing the occurrence of breakage and wrinkling during the manufacturing process and battery manufacturing and use. Using it as lithium-ion battery copper foil can improve battery cycle life and safety.

[0062] In one embodiment, the transverse tensile strength of the copper foil after baking at 200°C for 3 hours is defined as S3, in kgf / mm². 2 The lateral elongation is E3, the tensile strength attenuation rate is R3, and S0, E0, S3, E3, and R3 satisfy:

[0063] R3=(1-S3 / S0)*100%<30%, and E3-E0>0.

[0064] After baking at 200℃ for 3 hours, the copper foil exhibits a tensile strength decay rate R3 = (1-S3 / S0)*100% < 30% (including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, or 29%. Further, R3 < 20%. Even further, R3 < 15%. Still further, R3 < 10%.), and an elongation greater than the initial value. This indicates that the copper foil also possesses excellent thermal stability and maintains superior mechanical properties after high-temperature baking, thereby reducing the occurrence of breakage and wrinkling during the manufacturing process and battery manufacturing and use. Using it as lithium-ion battery copper foil can improve battery cycle life and safety.

[0065] Research has found that low tensile strength and low elongation of copper foil make it prone to breakage and wrinkling during the manufacturing process and cell fabrication, which greatly affects production efficiency and battery performance.

[0066] In one embodiment, the transverse tensile strength of the copper foil is 40 kgf / mm² under room temperature conditions (e.g., 10°C to 40°C, further 25°C). 2 ~90kgf / mm 2Copper foil meeting this requirement can reduce the occurrence of foil breakage and wrinkling during the manufacturing process and cell fabrication, thereby improving copper foil manufacturing and battery production efficiency, and ultimately enhancing battery capacity and safety performance. When the tensile strength of the copper foil is less than 40 kgf / mm²... 2 During the copper foil rolling, pressing, and winding process, breakage is prone to occur, severely affecting the battery's safety and cycle performance. On the other hand, the tensile strength of the copper foil is higher than 90 kgf / mm². 2 At the same time, it may be impossible to achieve the desired elongation, resulting in a lower elongation. Although this reduces the occurrence of strip breakage, it increases wrinkling and reduces the usability of the copper foil. For example, tearing may occur during the production of copper foil or during the production of electrodes for secondary batteries using copper foil, which may make it difficult to obtain a stable product.

[0067] Understandably, the transverse tensile strength of the copper foil described in this invention at room temperature (e.g., 10°C to 40°C, further 25°C) is, but is not limited to, 40 kgf / mm². 2 42kgf / mm 2 44kgf / mm 2 46kgf / mm 2 48kgf / mm 2 50kgf / mm 2 52kgf / mm 2 54kgf / mm 2 56kgf / mm 2 58kgf / mm 2 60kgf / mm 2 65kgf / mm 2 70kgf / mm 2 75kgf / mm 2 80kgf / mm 2 85kgf / mm 2 Or 90 kgf / mm 2 .

[0068] In one embodiment, under room temperature conditions (e.g., 10°C to 40°C, further 25°C), the lateral elongation of the copper foil is 3% or more. Copper foil meeting this requirement can reduce the occurrence of foil breakage and wrinkling during the manufacturing process and cell fabrication, thereby improving copper foil manufacturing and battery production efficiency, and enhancing battery capacity and safety performance. It is understood that the lateral elongation of the copper foil of the present invention under room temperature conditions (e.g., 10°C to 40°C, further 25°C) includes, but is not limited to, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0069] In one embodiment, the difference between the longitudinal (MD) tensile strength and the transverse (TD) tensile strength of the copper foil is 1 kgf / mm. 2 The difference between the MD and TD tensile strengths of the copper foil is controlled within 1 kgf / mm². 2 In addition to improving production efficiency and yield in the copper foil manufacturing process, this also enhances the production stability of the coating and rolling processes. Tensile strength fluctuations in the MD and TD directions are mainly related to copper foil thickness and additive stability. Greater fluctuations in copper foil thickness and imbalances in additive ratios will lead to greater tensile strength fluctuations in both the transverse and longitudinal directions. When the tensile strength difference in the MD direction exceeds 1 kgf / mm... 2 When the tension of each roller system remains constant during the coating and rolling processes, sudden wrinkling or breakage of the electrode sheet can easily occur, requiring a significant amount of time to recover. When the tensile strength difference in the TD direction exceeds 1 kgf / mm... 2 At the same time, under high tension parameters during coating and rolling, lateral wrinkling may occur, leading to a short circuit in the battery.

[0070] Studies have shown that, with a constant thickness, the tensile strength of copper foil increases as the grain size decreases. Tensile strength is closely related to the transfer of slip from plastically deformed grains to adjacent grains. Whether this transfer occurs depends primarily on whether the stress concentration generated by dislocation pile-ups near the grain boundaries of the already slipped grains can excite dislocation sources in the slip system of adjacent grains, enabling coordinated multi-slip. Furthermore, grain refinement generates more grain boundaries. More grain boundaries increase the resistance to dislocation slip, requiring greater external force to cause copper foil fracture. Moreover, more grain boundaries can absorb and release thermal stress, improving the stability of the copper foil under high-temperature conditions.

[0071] In one embodiment, at room temperature (e.g., 10°C to 40°C, further 25°C), the copper foil comprises more than 90% grains with a diameter less than 0.6 μm as a percentage of the total number of grains in the copper foil.

[0072] In one embodiment, after the copper foil is baked at 200°C for 1 hour, the copper foil comprises more than 90% grains with a particle size of less than 0.6 μm, based on the percentage of the total number of grains in the copper foil.

[0073] In one embodiment, after the copper foil is baked at 200°C for 2 hours, the copper foil comprises more than 90% grains with a particle size of less than 0.6 μm, based on the percentage of the total number of grains in the copper foil.

[0074] In one embodiment, after the copper foil is baked at 200°C for 3 hours, the copper foil comprises more than 90% grains with a particle size of less than 0.6 μm, based on the percentage of the total number of grains in the copper foil.

[0075] In one embodiment, the copper foil has a first surface and a second surface opposite to each other, the first surface having a gloss level of Gs1 and the second surface having a gloss level of Gs2, where Gs1 > Gs2, and the average grain difference between the first surface and the second surface satisfies:

[0076] Furthermore, the average grain size difference is less than 0.2 μm;

[0077] Where d1 represents the size of a single grain on the first surface, in μm, n d1 d1 represents the number of grains of size d1 in the first surface, and d2 represents the size of a single grain in the second surface, in μm. d2 This indicates the number of grains with size d2 in the second surface.

[0078] In this invention, the difference in average grain size between the two surfaces of the copper foil (for lithium-ion battery copper foil produced by electrolysis, the two surfaces refer to the deposition surface and the roller surface, respectively) is calculated using the above-mentioned formula for average grain size difference and is less than 0.2 μm. Smaller grains generate more grain boundaries; more grain boundaries require greater external force to cause the copper foil to break. Furthermore, more grain boundaries can absorb and release thermal stress, improving the stability of the copper foil under high-temperature conditions. Additionally, the difference in average grain size between the two surfaces affects warpage; the greater the difference, the greater the warpage. Taking electrolytic copper foil as an example, in the crystal structure, warpage is usually related to the grain size of the deposition surface and the roller surface. Smaller grains on the roller surface generate greater compressive stress, while larger grains on the deposition surface generate less compressive stress. Therefore, copper foil warpage always occurs with the roller surface facing the deposition surface. When the difference in grain size between the deposition surface and the roller surface exceeds 0.2 μm, the difference in compressive stress between the two surfaces is too large, resulting in greater warpage of the copper foil. Excessive warping will have the following effects on copper foil and battery respectively: (1) it will cause the copper foil to tear and the baking time to be long, affecting production efficiency and pass rate; (2) due to the warping defect of copper foil during the preparation of power battery, the negative electrode laser cutting of tabs is serious, and special personnel need to be arranged to pick the tabs, which is time-consuming and laborious, seriously affecting production efficiency and quality. If the internal tabs are not picked out to form a battery, the internal resistance of the battery will be reduced or there will be a risk of short circuit.

[0079] In one embodiment, the thickness of the copper foil is 3 μm to 12 μm. Copper foil that is too thick or too thin is detrimental to process stability or can lead to a decrease in battery performance. When the copper foil thickness is <3 μm, after the battery tabs are formed, during the high-speed laser die-cutting and winding process, the tabs are prone to folding or indentation, significantly reducing the production efficiency of the process and lowering the battery's internal resistance. When the copper foil thickness is >12 μm, the excessive thickness leads to a decrease in the content of active materials in the battery, affecting the battery's capacity density. The copper foil thickness can be controlled by adjusting the current and linear velocity during the manufacturing process.

[0080] The present invention also provides a method for preparing the copper foil as described above, the technical solution of which is as follows:

[0081] A method for preparing copper foil as described above, wherein the copper foil is prepared by electrolysis;

[0082] The electrolyte used in the electrolysis method comprises the following components:

[0083] Copper ions 90g / L±2g / L, sulfuric acid 105g / L±5g / L, chloride ions 23ppm±2ppm, brightener 40mg / L±20mg / L, leveling agent 12mg / L±8mg / L and leveling agent 12mg / L±8mg / L;

[0084] The brightening agent includes sulfur-containing compounds, the leveling agent includes nitrogen-containing amine organic compounds, and the positioning agent includes various polyether compounds, including at least polyethylene glycol.

[0085] In this invention, adding a certain proportion of brightener, leveling agent, and leveling agent to the electrolyte (or plating solution) can alter the deposition rate of copper foil and improve its mechanical properties. The brightener is mainly composed of sulfur-containing compounds, primarily promoting the nucleation of copper ions. The leveling agent is mainly composed of nitrogen-containing amine organic compounds, which promote face-centered cubic growth of the copper foil, resulting in smoother grains. When the organic sulfide brightener and the nitrogen-containing amine organic compound (such as a nitrogen-containing polymer) leveling agent are used together, the copper foil crystal structure becomes smoother and denser, generating numerous nanocrystalline regions and enhancing the fine-grain strengthening effect. The excellent structures of the fine grains and nanotwins interact to improve both the tensile strength and elongation of the copper foil. The leveling agent is a compound of various polyether compounds, including at least polyethylene glycol, which forms a more stable and uniform barrier layer, effectively limiting certain growth directions of the copper crystals. It interacts uniformly with other additives across various parts of the copper foil, resulting in finer and more uniform grains. In addition, polyether compounds can effectively inhibit grain growth at high temperatures, reduce grain nucleation size, generate more interfaces, absorb and release thermal stress, and improve the stability of copper foil under high-temperature conditions.

[0086] In one embodiment, the sulfur-containing compound includes one or more of sodium polydithiopropane sulfonate, sodium thiopropane sulfonate, sodium 3-mercapto-1-propanesulfonate, and sodium piperazine dithiocarbamate propanesulfonate.

[0087] In one embodiment, the nitrogen-containing amine organic compound includes one or more of polyethyleneimine alkyl compounds and collagen.

[0088] In one embodiment, the positioning agent is a compound of a first polyether compound and a second polyether compound in a concentration ratio of (1-2):1, wherein the first polyether compound is polyethylene glycol, and the second polyether compound includes one or more of octylphenol polyoxyethylene ether and ethylene oxide-propylene oxide block polyether compounds.

[0089] In one embodiment, the temperature of the electrolyte is 52°C ± 3°C.

[0090] In one embodiment, the current applied during the electrolysis process is 25000A ± 5000A.

[0091] In one embodiment, the method for preparing the copper foil as described above includes the following steps:

[0092] Using high-purity copper plates and / or copper wires (e.g., purity greater than or equal to 99.99%) as raw materials, copper sulfate electrolyte is prepared by dissolving them in sulfuric acid solution. After three-stage filtration, pure copper sulfate electrolyte is obtained. Then, the electrolyte solution is generated through filtration and a constant temperature system. The concentration of copper ions in the electrolyte is 90±2 g / L, the concentration of sulfuric acid is 105±5 g / L, the concentration of chloride ions is controlled at 23±2 ppm, and the temperature of the electrolyte is controlled at 52℃±3℃. Then, a uniformly mixed additive solution of brightener, leveling agent and sizing agent is added to the electrolyte. Using iridium-plated titanium sheet as anode and pure titanium sheet as cathode, under the action of DC power supply, the current is controlled at 25000A±5000A to generate the initial electrolytic copper foil on the cathode roller.

[0093] Understandably, for copper foil prepared by electrolysis, during the preparation process, the roller surface that is in direct contact with the cathode roller surface and has low gloss is the smooth surface, while the deposition surface is the rough surface with higher gloss.

[0094] The present invention also provides applications of the copper foil as described above, the technical solutions of which are as follows:

[0095] A lithium-ion battery copper foil includes the copper foil described above or the copper foil prepared according to the method described above. Understandably, the lithium-ion battery copper foil possesses the advantages of the copper foil described in this invention, exhibiting excellent thermal stability, high tensile strength, and high elongation. It maintains excellent mechanical properties even after high-temperature baking, thereby reducing breakage and wrinkling during the manufacturing process and battery manufacturing and use. Using it as a lithium-ion battery copper foil can improve battery cycle life and safety.

[0096] A current collector comprising lithium-ion battery copper foil as described above.

[0097] An electrode includes a current collector as described above. Further, the electrode includes a first active material layer, a current collector, and a second active material layer stacked together. Even further, the electrode is a cathode electrode, wherein the first active material layer comprises at least one or more active material combinations of graphite-based materials, metal oxides, and silicon-based materials, and the second active material layer comprises at least one or more active material combinations of graphite-based materials, metal oxides, and silicon-based materials.

[0098] A battery comprising the electrodes as described above.

[0099] An electrical device includes a battery as described above. It is understood that the electrical device is a conventional electrical device in the art, including but not limited to digital products, lighting products, vehicles, etc.

[0100] The present invention will be illustrated by the following specific embodiments.

[0101] In embodiments of the present invention, the tensile strength and elongation of the samples were tested using a HY-0230 universal testing machine manufactured by Shanghai Hengyi Precision Instruments Co., Ltd., according to the test method of GB / T29847-2013, at room temperature and a strain rate of 50 mm / min. Generally, strips with a length and width of 100 mm and 12.7 mm respectively were cut from the samples. Five tests were conducted on each group of samples, and the calculated average value was used as the final tensile strength or elongation.

[0102] Example 1

[0103] (1) Electrolytic copper foil and its preparation method:

[0104] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 33 mg / L, polyethyleneimine alkyl salt was 9 mg / L, polyethylene glycol was 7 mg / L, octylphenol polyoxyethylene ether was 5 mg / L, and Cl... -Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0105] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0106] (2) Method for preparing secondary battery electrodes

[0107] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0108] Example 2

[0109] (1) Electrolytic copper foil preparation method:

[0110] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 37 mg / L, polyethyleneimine alkyl salt was 12 mg / L, polyethylene glycol was 7 mg / L, octylphenol polyoxyethylene ether was 5 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0111] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0112] (2) Method for preparing secondary battery electrodes

[0113] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0114] Example 3

[0115] (1) Electrolytic copper foil preparation method:

[0116] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 37 mg / L, sodium polydisulfide dipropanesulfonate was 13 mg / L, polyethyleneimine alkyl salt was 15 mg / L, polyethylene glycol was 9 mg / L, octylphenol polyoxyethylene ether was 7 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0117] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0118] (2) Method for preparing secondary battery electrodes

[0119] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0120] Example 4

[0121] (1) Electrolytic copper foil preparation method:

[0122] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 37 mg / L, sodium polydisulfide dipropanesulfonate was 18 mg / L, polyethyleneimine alkyl salt was 15 mg / L, polyethylene glycol was 9 mg / L, octylphenol polyoxyethylene ether was 7 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0123] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0124] (2) Method for preparing secondary battery electrodes

[0125] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0126] Comparative Example 1

[0127] (1) Electrolytic copper foil preparation method:

[0128] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium polydisulfide dipropane sulfonate was 37 mg / L, collagen was 12 mg / L, polyethylene glycol was 6 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0129] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0130] (2) Method for preparing secondary battery electrodes

[0131] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0132] Comparative Example 2

[0133] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 37 mg / L, alkyl polyimide was 12 mg / L, polyethylene glycol was 7 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0134] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0135] (2) Method for preparing secondary battery electrodes

[0136] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0137] Comparative Example 3

[0138] Copper raw material is dissolved in sulfuric acid solution to obtain the initial electrolyte. Then, a certain concentration of chloride ions and additive solution are added to obtain the electrolyte solution. The Cu in the electrolyte... 2+ The concentration was 90±2 g / L, the concentration of H2SO4 was 105±5 g / L, sodium 3-mercapto-1-propanesulfonate was 37 mg / L, polyethyleneimine alkyl salt was 12 mg / L, octylphenol polyoxyethylene ether was 5 mg / L, and Cl... - Provided by hydrochloric acid, with a flow rate of 5.5 L / H, Cl - The concentration was controlled at 23±2 ppm, and the electrolyte flow rate was 42±2 m³ / min. 3 / h, the temperature of the electrolyte is controlled at 52℃±3℃. Under the action of DC power supply (current is 25000A), copper ions undergo redox reaction to generate copper foil on the surface of the cathode roller. After passivation and aging, a copper foil sample with stable physical properties is obtained at room temperature. Its tensile strength and elongation are tested. The detailed results are shown in Table 1.

[0139] The room temperature samples were placed in an electric thermostatic drying oven with heating and blowing functions. They were baked for 1, 2 and 3 hours at a set temperature of T = 200℃. The tensile strength and elongation of the baked samples were then tested. The detailed results are shown in Table 1.

[0140] (2) Method for preparing secondary battery electrodes

[0141] 95 parts of commercially available graphite anode material, 1 part CMC (carboxymethyl cellulose), 2 parts conductive carbon black, and 1 part (styrene-butadiene rubber) were dissolved in high-purity water and stirred evenly to form a stable slurry with a certain viscosity. Next, the resulting slurry was evenly coated onto both surfaces of the prepared electrolytic copper foil using a scraper. The coated copper foil was then rolled and die-cut into anode sheets with a thickness of 105 μm and a width of 82.5 mm. Then, through winding and assembly processes, the positive electrode sheet, separator, and negative electrode sheet were wound into a tightly fitted core. After the core was paired and housed, a sealed lithium-ion battery cell was formed. Finally, 20 cells were selected and, after charge-discharge cycles, disassembled. The appearance of broken strips (electrode breakage) and wrinkles (electrode folds) on the negative electrode sheets was observed. The results are shown in Table 2.

[0142] Table 1. Physical property data of lithium battery copper foil before and after high-temperature baking for each comparative example.

[0143]

[0144] Table 2. Test results of the microstructure and basic physical properties of the electrolytic copper foils prepared in each embodiment and comparative example.

[0145]

[0146] As shown in Tables 1 and 2, compared with Comparative Examples 1 to 3, the copper foils provided in Examples 1 to 4 of the present invention exhibit lower tensile strength decay rates and greater elongation rates after baking at 200°C for 1 hour, 2 hours, or 3 hours, indicating superior thermal stability. They also maintain excellent mechanical properties after high-temperature baking. When used as copper foil for lithium batteries, they can reduce breakage and wrinkling during use, thereby improving battery cycle life and safety.

[0147] Figure 1 These are EBSD images of the roller surface and deposition surface of the copper foil prepared using Example 1, wherein... Figure 1 (a) is an EBSD image of the roller surface. Figure 1 (b) is an EBSD image of the sedimentary surface, created by... Figure 1 It can be seen that the grain size on the roller surface is smaller than that on the deposition surface. Calculations show that 92% of the grains on the roller surface have a grain size <0.6μm.

[0148] Figure 2 These are EBSD images of the roller surface and deposition surface of the copper foil prepared using Comparative Example 1, where... Figure 2 (a) is an EBSD image of the roller surface. Figure 2 (b) is an EBSD image of the sedimentary surface, created by... Figure 2It can be seen that the grain size on the roller surface is smaller than that on the deposition surface, and the proportion of grains with a size <0.6μm on the roller surface is 79%.

[0149] In summary, the copper foil provided by this invention has fine and uniform grains and a flat and dense crystal structure, which improves the tensile strength and elongation of the copper foil. It also has good thermal stability. After baking at 200°C for 1 hour, 2 hours or 3 hours, its tensile strength decay rate is low and its elongation is greater than that at room temperature. This indicates that it can still maintain excellent mechanical properties after high-temperature baking. Therefore, it can reduce the occurrence of breakage and wrinkling of copper foil during manufacturing and battery manufacturing and use. Using it as lithium battery copper foil can improve the cycle life and safety of the battery.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A copper foil, characterized by, The transverse tensile strength of the copper foil at room temperature is defined as S0, in kgf / mm². 2 The transverse elongation is E0. The transverse tensile strength of the copper foil after baking at 200℃ for 1 hour is S1, with units of kgf / mm². 2 The lateral elongation is E1, the tensile strength attenuation rate is R1, and S0, E0, S1, E1, and R1 satisfy: R1=(1-S1 / S0)*100%<10%, and E1-E0>0; The copper foil includes more than 90% of grains with a particle size less than 0.6 μm in percentage of total grain number in the copper foil under room temperature conditions.

2. The copper foil according to claim 1, characterized by, The copper foil satisfies one or more of the following (1)~(2): (1) The copper foil is baked at 200°C for 2h, and the transverse tensile strength of the copper foil is S2, kgf / mm 2 , the transverse elongation is E2, and the tensile strength decay rate is R2. The S0, E0, S2, E2, and R2 satisfy: R2=(1-S2 / S0)*100%<20%, and E2-E0>0; (2) record the tensile strength S3 in kgf / mm2, the transverse elongation E3, and the tensile strength decay rate R3 of the copper foil after baking at 200°C for 3h 2 , wherein S0, E0, S3, E3, and R3 satisfy the following conditions: R3=(1-S3 / S0)*100%<30%, and E3-E0>0.

3. The copper foil according to claim 1, characterized by, The copper foil satisfies one or more of the following (1)~(2): (1) The copper foil has a transverse tensile strength of 40 kgf / mm 2 90 kgf / mm 2 at room temperature. (2) The transverse elongation of the copper foil is more than 3% under room temperature conditions.

4. The copper foil according to any one of claims 1 to 3, characterized by The difference between the longitudinal tensile strength and the transverse tensile strength of the copper foil is 1 kgf / mm 2 The following.

5. The copper foil according to any one of claims 1 to 3, characterized by The copper foil satisfies: under 200℃ conditions, after baking treatment of the copper foil for 1h, the copper foil includes more than 90% of grains with a particle size less than 0.6 μm in percentage of total grain number in the copper foil.

6. The copper foil according to any one of claims 1 to 3, characterized by The copper foil has opposite first and second surfaces, the first surface has a glossiness of Gs1, the second surface has a glossiness of Gs2, Gs1>Gs2, and the average grain difference of the first and second surfaces satisfies: and the average grain difference is less than 0.2 μm; wherein d1 represents a single grain size of the first surface, in μm, N1 represents a number of grains having a size d1 in the first surface, and d2 represents a single grain size of the second surface, in μm, N2 represents a number of grains having a size d2 in the second surface.

7. The copper foil according to any one of claims 1 to 3, characterized by The thickness of the copper foil is 3 μm~12 μm.

8. A method of producing the copper foil according to any one of claims 1 to 7, characterized by, The copper foil is prepared by an electrolytic method; The electrolyte used in the electrolytic method includes the following components: Copper ions 90 g / L±2 g / L, sulfuric acid 105 g / L±5 g / L, chloride ions 23 ppm±2 ppm, brightener 40 mg / L±20 mg / L, leveling agent 12 mg / L±8 mg / L, and walking agent 12 mg / L±8 mg / L; The brightener includes a sulfur-containing group compound, the leveling agent includes a nitrogen-containing amine organic matter, the walking agent includes a plurality of polyether compounds, and at least includes polyethylene glycol.

9. The production method according to claim 8, characterized by, Satisfy one or more of the following (1)~(3): (1) The sulfur-containing group compound includes one or more of polydithiodipropyl sulfone sodium, alcohol sulfur group propane sulfone sodium, 3-mercapto-1-propane sulfonic acid sodium, and piperazine dithioformic acid propyl sulfonic acid sodium; (2) The nitrogen-containing amine organic matter includes one or more of polyethylene imine alkyl compound and collagen; (3) The walking agent is compounded by a first polyether compound and a second polyether compound according to a concentration ratio (1~2):1, wherein the first polyether compound is polyethylene glycol, and the second polyether compound includes one or more of octylphenol polyoxyethylene ether and oxirane propylene oxide block polyether compound.

10. The production method according to claim 8 or 9, characterized by, Satisfy one or more of the following (1)~(2): (1) The temperature of the electrolyte is 52℃±3℃; (2) The current applied in the electrolytic method is 25000A±5000A.

11. A lithium-impregnated copper foil, characterized by, The copper foil includes any one of claims 1~7, or the copper foil prepared by the preparation method of any one of claims 8~10.

12. A current collector characterized by comprising: The lithium battery copper foil includes claim 11.

13. A pole piece characterized by, The current collector includes claim 12.

14. A battery, characterized by The pole piece includes claim 13.

15. An electrical device, comprising: The battery includes claim 14.

Images