Method for producing rolled copper foil, rolled copper foil, and application

Abstract

The application provides a preparation method of a calendered copper foil, the calendered copper foil and application. The preparation method of the calendered copper foil comprises a copper foil rolling step: a base material is sequentially subjected to multi-pass rolling, and at least one annealing process is additionally arranged in the middle of the multi-pass rolling process, so that the calendered copper foil is prepared. In the preparation method of the calendered copper foil, the annealing process is additionally arranged in the middle of the multi-pass rolling process, so that the ductility and the flexibility of the calendered copper foil are improved, and the bending resistance of the calendered copper foil is improved. When the calendered copper foil prepared by the embodiment is used in a lithium battery, the special use requirements of the lithium battery can be met, and the use scale of the calendered copper foil in the lithium battery field can be improved.

Description

Technical Field

[0001] This invention relates to the field of rolled copper foil processing technology, and in particular to the preparation method of rolled copper foil, rolled copper foil and its applications. Background Technology

[0002] Copper foil is produced by first melting and casting copper into copper ingots, then hot rolling, rough rolling, and fine rolling into base material, and finally rolling it repeatedly in a rolling mill.

[0003] Compared to electrolytic copper foil, rolled copper foil has the following advantages: ① The internal structure of rolled copper foil is mostly lamellar crystals, while that of electrolytic copper foil is a single layer of needle-like particles. Rolled copper foil is superior to electrolytic copper foil in terms of elongation, folding endurance, and high-temperature recrystallization; ② At the same thickness, rolled copper foil has a higher copper content and density than electrolytic copper foil, resulting in significant anti-breakdown performance; ③ Rolled copper foil has relatively lower roughness and excellent bending resistance. Therefore, rolled copper foil has unparalleled advantages in the application of lithium batteries for foldable electronic devices.

[0004] Rolled copper foil is mainly used as a current collector in the negative electrode of lithium batteries. However, the bending resistance of existing rolled copper foil for lithium batteries still needs improvement, and it cannot meet the special requirements of lithium batteries. This has become a key bottleneck restricting the development and application of rolled copper foil in the lithium battery field.

[0005] Therefore, there is an urgent need in the existing technology for a method to prepare rolled copper foil that improves the bending resistance of rolled copper foil. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide a method for preparing rolled copper foil, rolled copper foil and its application that overcomes or at least partially solves the above problems. It can solve the problem that the bending resistance of rolled copper foil for lithium batteries needs to be improved in the prior art, so as to meet the special requirements of lithium batteries.

[0007] This invention provides a method for preparing rolled copper foil, comprising:

[0008] Copper foil rolling process: The base material is rolled in multiple passes in sequence, and at least one annealing process is added in the middle of the multiple rolling processes to prepare rolled copper foil.

[0009] Optionally, the method for preparing the rolled copper foil further includes:

[0010] The base material preparation steps are as follows: copper is smelted and processed, and then successively cast into ingots, hot rolled into billets, rough rolled, fine rolled and annealed to obtain the base material; the thickness of the base material is 80μm~150μm;

[0011] The base material is in a soft state and is made of pure copper.

[0012] The thickness of the rolled copper foil obtained by the copper foil rolling step is 9 μm to 9.1 μm.

[0013] Optionally, at least one annealing process may be added between the multiple rolling processes, including:

[0014] An annealing process is added between any group of adjacent rolling passes;

[0015] In multi-pass rolling processes, the rolling pass following the annealing process has the highest reduction rate.

[0016] Optionally, the copper foil rolling process is divided into 4 to 7 rolling passes, and an annealing process is added between the second and third rolling passes.

[0017] The reduction rate is highest in the third rolling process;

[0018] In the multi-pass rolling process, the target plate shapes may be all equal, not all equal, or not all equal.

[0019] Optionally, the copper foil rolling process is divided into 7 rolling passes, and an annealing process is added between the second and third rolling passes.

[0020] The reduction rate of the third rolling pass > the reduction rate of the fourth rolling pass > the reduction rate of the first rolling pass > the reduction rate of the second rolling pass > the reduction rate of the fifth rolling pass > the reduction rate of the sixth rolling pass > the reduction rate of the seventh rolling pass.

[0021] Optionally, the copper foil rolling step specifically includes the following processes:

[0022] The first rolling process has a reduction rate of 35% to 38%, a total inlet tension of 4500N to 5000N, a total outlet tension of 5500N to 6000N, a rolling speed of 200m / min to 250m / min, a rolling force of 350kN to 400kN, and a bending force of 1 to 3MPa.

[0023] The second rolling process has a reduction rate of 25% to 30%, a total inlet tension of 4500N to 5000N, a total outlet tension of 3500N to 4000N, a rolling speed of 150m / min to 200m / min, a rolling force of 350kN to 400kN, and a bending force of 1 to 3MPa.

[0024] Annealing process: Hold at 150-250℃ for 1-4 hours;

[0025] The third rolling process has a reduction rate of 48% to 52%, a total inlet tension of 2000N to 2200N, a total outlet tension of 2000N to 2200N, a rolling speed of 200m / min to 230m / min, a rolling force of 400kN to 450kN, and a bending force of 1 to 3MPa.

[0026] The fourth rolling process: the reduction rate is 40% to 42%, the total inlet tension is 1100N to 1300N, the total outlet tension is 1300N to 1500N, the rolling speed is 330m / min to 350m / min, the rolling force is 450kN to 500kN, and the bending force is 1 to 3MPa.

[0027] The fifth rolling process: the reduction rate is 25% to 28%, the total inlet tension is 800N to 1000N, the total outlet tension is 700N to 900N, the rolling speed is 200m / min to 230m / min, the rolling force is 400kN to 450kN, and the bending force is 1 to 3MPa.

[0028] The sixth rolling process: the reduction rate is 22% to 25%, the total inlet tension is 600N to 650N, the total outlet tension is 600N to 650N, the rolling speed is 250m / min to 300m / min, the rolling force is 350kN to 400kN, and the bending force is 1 to 3MPa.

[0029] The seventh rolling process has a reduction rate of 20% to 22%, a total inlet tension of 400N to 500N, a total outlet tension of 400N to 500N, a rolling speed of 350m / min to 400m / min, a rolling force of 450kN to 500kN, and a bending force of 1 to 3MPa.

[0030] Optionally, after the copper foil rolling step, the process further includes:

[0031] Surface treatment step: Perform surface treatment on the rolled copper foil;

[0032] The surface treatment steps include reddening, blackening, or ash treatment processes.

[0033] Optionally, the surface treatment step includes a reddening treatment process;

[0034] In the reddening process, chemical degreasing, electrolytic degreasing, pickling, roughening, curing, zinc plating, and chromium plating are performed sequentially to form a red-treated surface on the rolled copper foil.

[0035] In the chemical degreasing process, the concentration of NaOH in the chemical degreasing solution is 20g / L to 30g / L, the concentration of Na2CO3 is 30g / L to 40g / L, and the content of sodium silicate is 1% to 5%.

[0036] In the electrolytic degreasing process, the electrolytic degreasing solution has the same composition as the chemical degreasing solution. The operating temperature of the electrolytic degreasing solution is 30℃~60℃, the electrode distance is 60mm, and the current density is 1800A / m. 2 ;

[0037] In the roughening process, Cu in the electroplating solution 2+ The concentration of H₂SO₄ in the electroplating solution is 12 g / L to 14 g / L, the concentration of H₂SO₄ in the electroplating solution is 230 g / L to 250 g / L, and the temperature of the electroplating solution is 30℃ to 40℃; the electrode distance is 60 mm, and the current density is 1800 A / m. 2 The coarsening time is 5 to 10 seconds;

[0038] In the curing process, Cu in the electroplating solution 2+ The concentration of H₂SO₄ in the electroplating solution is 45 g / L to 80 g / L, the concentration of H₂SO₄ in the electroplating solution is 130 g / L to 160 g / L, and the temperature of the electroplating solution is 35℃ to 50℃; the electrode distance is 60 mm, and the current density used is 3400 A / m. 2 The curing time is 5 to 10 seconds;

[0039] In the zinc plating process, the Zn in the electroplating solution 2+ The concentration of the electrolyte was 2.0 g / L to 4.0 g / L, the concentration of potassium pyrophosphate was 35 g / L to 55 g / L, the pH was 10.8 to 11.8, the temperature of the electroplating solution was 35℃ to 55℃, and the current density was 1000 A / m. 2 The electroplating time is 3 to 8 seconds;

[0040] In the chromium plating process, the concentration of CrO3 in the electroplating solution is 3.5 g / L to 3.8 g / L, the concentration of NaOH is 22 g / L to 25 g / L, the temperature of the electroplating solution is 25℃ to 28℃, the current is 60 A, the electroplating time is 3 to 8 seconds, and the electrode distance is 60 mm.

[0041] On the other hand, the present invention also provides a rolled copper foil prepared by any of the above-described preparation methods.

[0042] Furthermore, the present invention also provides an application of rolled copper foil prepared by any of the above-described preparation methods in the fields of lithium metal batteries, electrocatalysis, or sensing.

[0043] In the method for preparing rolled copper foil of the present invention, by adding an annealing process in the middle of the multi-pass rolling process, the ductility and flexibility of the rolled copper foil can be improved, thereby enhancing its bending resistance. When the rolled copper foil prepared using this embodiment is used in lithium batteries, it can meet the special application requirements of lithium batteries, thereby increasing the scale of application of rolled copper foil in the lithium battery field.

[0044] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0045] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0046] Figure 1 This is a schematic flowchart of a method for preparing rolled copper foil according to an embodiment of the present invention. Detailed Implementation

[0047] The following reference Figure 1 This invention describes a method for preparing rolled copper foil, the rolled copper foil itself, and its applications. In this description, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0048] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] In existing technologies, copper foil rolling involves multiple rolling passes, but annealing is not included between adjacent passes. Therefore, the rolled copper foil obtained through existing rolling processes exhibits poor ductility, flexibility, and bending performance, failing to meet the specific requirements of lithium batteries. To address these issues, this application adds an annealing process to the copper foil rolling process to increase the ductility of the rolled copper foil, thereby improving its bending resistance.

[0050] This invention provides a method for preparing rolled copper foil.

[0051] A method for preparing rolled copper foil includes a copper foil rolling step.

[0052] Copper foil rolling process: The base material is rolled in multiple passes in sequence, and at least one annealing process is added in the middle of the multiple rolling processes to prepare rolled copper foil.

[0053] Specifically, "adding at least one annealing process in the middle of a multi-pass rolling process" means adding at least one annealing process between at least one group of adjacent rolling passes. For example: adding one annealing process between one group of adjacent rolling passes; or adding one annealing process between at least two groups of adjacent rolling passes; or adding at least two annealing processes between one group of adjacent rolling passes; or adding at least two annealing processes between at least two groups of adjacent rolling passes. The location and number of annealing processes can be set as needed.

[0054] Annealing is a metal heat treatment process that involves slowly heating a metal to a certain temperature, holding it for a sufficient time, and then cooling it at a suitable rate. The benefits of annealing include: reducing hardness and improving machinability; reducing residual stress, stabilizing dimensions, and reducing deformation and cracking tendency; refining grain size, adjusting microstructure, and eliminating structural defects.

[0055] Because rolling copper foil produces a large number of dislocations and grain fragmentation, resulting in smaller grain sizes, the material's hardness and tensile strength are greatly increased. This leads to a higher work hardening rate when the copper foil is rolled further. After annealing, the dislocations within the grains are effectively restored, and recrystallization occurs to some extent. This phenomenon helps improve the material's elongation and facilitates the thinning of the copper foil.

[0056] In this embodiment, by adding an annealing process in the middle of the multi-pass rolling process, the ductility and flexibility of the rolled copper foil can be improved, thereby enhancing its bending resistance. When the rolled copper foil prepared using this embodiment is used in lithium batteries, it can meet the specific requirements of lithium batteries, thus increasing the scale of application of rolled copper foil in the lithium battery field.

[0057] In some embodiments of the present invention, the method for preparing rolled copper foil further includes a base material preparation step.

[0058] The preparation steps of the base material are as follows: copper is smelted and processed, and then successively cast into ingots, hot rolled into billets, rough rolled, fine rolled and annealed to obtain the base material.

[0059] In some alternative embodiments of the present invention, the method for preparing rolled copper foil does not include a base material preparation step; that is, the base material used in the copper foil rolling step can be purchased externally.

[0060] In some embodiments of the present invention, the thickness of the base material is 80 μm to 150 μm.

[0061] For example, the thickness of the base material is any one of 80μm, 90μm, 100μm, 101μm, 105μm, 110μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm or 150μm.

[0062] Preferably, the thickness of the base material is 101 μm to 150 μm.

[0063] More preferably, the thickness of the base material is 150 μm.

[0064] Using a 150μm thick base material can reduce the production cost of rolled copper foil compared to using a thinner base material.

[0065] In some embodiments of the present invention, the base material is in a soft state and is made of pure copper.

[0066] Specifically, the base material is industrial pure copper, also known as red copper.

[0067] Preferably, the copper grade is C1100. In some alternative embodiments, the base material may also be other grades of industrial pure copper.

[0068] In some embodiments of the present invention, the thickness of the rolled copper foil obtained by the copper foil rolling step is 9 μm to 9.1 μm.

[0069] For example, rolled copper foil has a thickness of 9μm, 9.05μm, 9.06μm, 9.07μm, 9.08μm, 9.09μm or 9.1μm.

[0070] In some embodiments of the present invention, at least one annealing process is added in the middle of the multi-pass rolling process, including: adding an annealing process between any group of adjacent rolling processes; in the multi-pass rolling process, the reduction rate of the corresponding rolling process after the annealing process is the largest.

[0071] For example: In the copper foil rolling process, there are four or more rolling steps (e.g., 4, 5, 6, or 7 passes), and the annealing process is located between the second and third rolling steps, with the third rolling step having the largest reduction rate. Alternatively, in the copper foil rolling process, there are five or more rolling steps, and the annealing process is located between the third and fourth rolling steps, with the fourth rolling step having the largest reduction rate. Or, in the copper foil rolling process, there are four or more rolling steps, and the annealing process is located between the first and second rolling steps, with the second rolling step having the largest reduction rate.

[0072] In this embodiment, the ductility of the copper foil increases after the annealing process. Therefore, setting the reduction rate of the corresponding rolling process after the annealing process to the maximum not only improves the overall processing efficiency of the copper foil, but also makes it less likely for defects such as cracks to appear on the surface of the copper foil.

[0073] In some preferred embodiments of the present invention, the copper foil rolling process includes 4 to 7 rolling passes (e.g., 4, 5, 6, or 7 passes), and an annealing process is added between the second and third rolling passes. The reduction rate is the highest in the third rolling pass.

[0074] In this embodiment, the annealing process is set between the second and third rolling passes, which ensures both the ductility of the copper foil and the work hardening rate of the copper foil.

[0075] In some alternative embodiments of the present invention, the target plate shape is equal in all multiple rolling processes.

[0076] For example: the target board type is 2I.

[0077] In some embodiments of the present invention, the target plate shapes are not all equal in a multi-pass rolling process.

[0078] In some embodiments of the present invention, the target plate shapes are all different in the multi-pass rolling process.

[0079] In the above embodiments, the plate shape intuitively refers to the flatness of the copper foil, but in essence, it is the distribution of residual stress inside the copper foil. The target plate shape in each rolling process can be set as needed.

[0080] In some embodiments of the present invention, the copper foil rolling process is divided into 7 rolling passes, and an annealing process is added between the second and third rolling passes.

[0081] The reduction rate of the third rolling pass > the reduction rate of the fourth rolling pass > the reduction rate of the first rolling pass > the reduction rate of the second rolling pass > the reduction rate of the fifth rolling pass > the reduction rate of the sixth rolling pass > the reduction rate of the seventh rolling pass.

[0082] In this embodiment, the above-described configuration ensures both the ductility and work hardening rate of the copper foil. In other words, this embodiment achieves a good balance between the ductility and work hardening rate of the copper foil.

[0083] In some embodiments of the present invention, the copper foil rolling step specifically includes the following processes:

[0084] First rolling pass: reduction rate 35%–38% (e.g., any one of 35%, 36%, 37%, or 38%), total inlet tension 4500N–5000N (e.g., any one of 4500N, 4600N, 4700N, 4800N, 4900N, or 5000N), total outlet tension 5500N–6000N (e.g., any one of 5500N, 5600N, 5700N, 5800N, 5900N, or 6000N), rolling speed… The rolling speed is 200m / min to 250m / min (e.g., any one of 200m / min, 210m / min, 220m / min, 230m / min, 240m / min or 250m / min), the rolling force is 350kN to 400kN (e.g., any one of 350kN, 360kN, 370kN, 380kN, 390kN or 400kN), and the bending force is 1 to 3MPa (e.g., any one of 1MPa, 2MPa or 3MPa).

[0085] The second rolling pass: A reduction rate of 25%–30% (e.g., any one of 25%, 26%, 27%, 28%, or 30%), a total inlet tension of 4500N–5000N (e.g., any one of 4500N, 4600N, 4700N, 4800N, 4900N, or 5000N), and a total outlet tension of 3500N–4000N (e.g., any one of 3500N, 3600N, 3700N, 3800N, 3900N, or 4000N). The rolling speed is 150m / min to 200m / min (e.g., any one of 150m / min, 160m / min, 170m / min, 180m / min, 190m / min or 200m / min), the rolling force is 350kN to 400kN (e.g., any one of 350kN, 360kN, 370kN, 380kN, 390kN or 400kN), and the bending force is 1 to 3MPa (e.g., any one of 1MPa, 2MPa or 3MPa).

[0086] Annealing process: Holding at 150–250°C for 1–4 hours. Specifically, the holding temperature is 150–250°C (e.g., any one of 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C), and the holding time is 1–4 hours (e.g., any one of 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours). Preferably, the annealing process includes: holding at 200°C for 3 hours; that is, the holding temperature in the annealing process is 200°C, and the holding time is 3 hours.

[0087] The third rolling pass: reduction rate of 48%–52% (e.g., any one of 48%, 49%, 50%, 51%, or 52%), total inlet tension of 2000N–2200N (e.g., any one of 2000N, 2100N, 2150N, or 2200N), total outlet tension of 2000N–2200N (e.g., any one of 2000N, 2050N, 2100N, 2150N, or 2200N), rolling speed of 200m / s. The rolling speed is 200 m / min to 230 m / min (e.g., any one of 200 m / min, 205 m / min, 210 m / min, 215 m / min, 220 m / min or 230 m / min), the rolling force is 400 kN to 450 kN (e.g., any one of 400 kN, 410 kN, 420 kN, 430 kN, 440 kN or 450 kN), and the bending force is 1 to 3 MPa (e.g., any one of 1 MPa, 2 MPa or 3 MPa).

[0088] Fourth rolling pass: Reduction rate of 40% to 42% (e.g., any one of 40%, 41%, 41.5%, or 42%), total inlet tension of 1100N to 1300N (e.g., any one of 1100N, 1150N, 1200N, or 1300N), and total outlet tension of 1300N to 1500N (e.g., any one of 1300N, 1350N, 1400N, 1450N, or 1500N). The rolling speed is 330m / min to 350m / min (e.g., any one of 330m / min, 340m / min, or 350m / min), the rolling force is 450kN to 500kN (e.g., any one of 450kN, 460kN, 470kN, 480kN, 490kN, or 500kN), and the bending force is 1 to 3MPa (e.g., any one of 1MPa, 2MPa, or 3MPa).

[0089] The fifth rolling pass: The reduction rate is 25%–28% (e.g., any one of 25%, 26%, 27%, or 28%), the total inlet tension is 800N–1000N (e.g., any one of 800N, 900N, 950N, or 1000N), the total outlet tension is 700N–900N (e.g., any one of 700N, 750N, 800N, 850N, or 900N), and the rolling speed is 200m / min–230m / min. / min (e.g., any one of the rolling speeds of 200m / min, 205m / min, 210m / min, 215m / min, 220m / min or 230m / min), rolling force of 400kN to 450kN (e.g., any one of the rolling forces of 400kN, 410kN, 420kN, 430kN, 440kN or 450kN), and bending force of 1 to 3MPa (e.g., any one of the bending forces of 1MPa, 2MPa or 3MPa).

[0090] The sixth rolling pass: A reduction rate of 22%–25% (e.g., any one of 22%, 23%, 24%, or 25%), a total inlet tension of 600N–650N (e.g., any one of 600N, 620N, 640N, or 650N), a total outlet tension of 600N–650N (e.g., any one of 600N, 620N, 630N, 640N, or 650N), and a rolling speed of 250m / min–300m / min. The rolling speed is 350kN to 400kN (e.g., any one of 250kN, 260kN, 270kN, 280kN, 290kN, or 300kN), the rolling force is 350kN to 400kN (e.g., any one of 350kN, 360kN, 370kN, 380kN, 390kN, or 400kN), and the bending force is 1 to 3MPa (e.g., any one of 1MPa, 2MPa, or 3MPa).

[0091] The seventh rolling pass: The reduction rate is 20%–22% (e.g., any one of 20%, 21%, 21.5%, or 22%), the total inlet tension is 400N–500N (e.g., any one of 400N, 450N, 480N, or 500N), the total outlet tension is 400N–500N (e.g., any one of 400N, 450N, 480N, or 500N), and the rolling speed is 350m / min–400m / min. (e.g., any one of the following rolling speeds: 350m / min, 360m / min, 370m / min, 380m / min, 390m / min, or 400m / min), rolling force of 450kN to 500kN (e.g., any one of the following rolling forces: 450kN, 460kN, 470kN, 480kN, 490kN, or 500kN), and bending force of 1 to 3MPa (e.g., any one of the following bending forces: 1MPa, 2MPa, or 3MPa).

[0092] Specifically, in this embodiment, the thickness of the base material used is 150 μm, and the thickness of the rolled copper foil obtained is 9.1 μm.

[0093] In this embodiment, the above-described configuration ensures both the ductility and work hardening rate of the copper foil. In other words, this embodiment achieves a good balance between the ductility and work hardening rate of the copper foil.

[0094] In this embodiment, a 150μm base material can be rolled into a 9.1μm rolled copper foil, and its mechanical properties can be measured by a universal testing machine to meet the mechanical property requirements of lithium-ion rolled copper foil. This provides, and only provides, a rolling method applicable only to the production of 9.1μm rolled copper foil from a 150μm base material.

[0095] In some embodiments of the present invention, after the copper foil rolling step, the method for preparing rolled copper foil further includes a surface treatment step.

[0096] Surface treatment step: The rolled copper foil is subjected to surface treatment to improve its corrosion resistance.

[0097] The surface treatment steps include reddening, blackening, or graying.

[0098] In existing technologies, copper foil is easily oxidized and corroded by electrolytes, limiting its large-scale application in lithium batteries. Therefore, this embodiment improves the corrosion resistance of copper foil by performing surface treatment, making it more suitable for use in the lithium battery field.

[0099] Preferably, in some embodiments of the present invention, the surface treatment step includes a reddening treatment step.

[0100] On the one hand, red-curing treatment significantly improves the corrosion resistance of rolled copper foil, enabling it to meet the performance requirements of lithium batteries. On the other hand, compared with blackening or graying treatments, red-curing treatment is simpler, cheaper, and more economical.

[0101] In some embodiments of the present invention, the reddening process involves sequential chemical degreasing, electrolytic degreasing, pickling, roughening, curing, and zinc and chromium plating processes to form a red-treated surface on the surface of the rolled copper foil.

[0102] In some embodiments of the present invention, in the chemical degreasing process, the concentration of NaOH in the chemical degreasing solution is 20 g / L to 30 g / L (e.g., 20 g / L, 24 g / L, 26 g / L, 27 g / L, 28 g / L or 30 g / L), the concentration of Na2CO3 is 30 g / L to 40 g / L (e.g., 30 g / L, 32 g / L, 35 g / L, 36 g / L, 38 g / L or 40 g / L), and the content of sodium silicate is 1% to 5% (e.g., 1%, 2%, 3%, 4% or 5%).

[0103] In some embodiments of the present invention, in the electrolytic degreasing process, the electrolytic degreasing solution has the same composition as the chemical degreasing solution, the operating temperature of the electrolytic degreasing solution is 30℃~60℃ (e.g., 30℃, 40℃, 50℃ or 60℃), the electrode distance is 60mm, and the current density is 1800A / m. 2 .

[0104] In some embodiments of the present invention, during the roughening process, Cu in the electroplating solution 2+ The concentration of H₂SO₄ in the electroplating solution is 12 g / L to 14 g / L (e.g., 12 g / L, 13 g / L, or 14 g / L), the concentration of H₂SO₄ in the electroplating solution is 230 g / L to 250 g / L (e.g., 230 g / L, 230 g / L, or 250 g / L), the temperature of the electroplating solution is 30℃ to 40℃ (e.g., 30℃, 35℃, 38℃, or 40℃), the electrode distance is 60 mm, and the current density is 1800 A / m. 2 The roughening time is 5 to 10 seconds (preferably, the curing time is 8 seconds).

[0105] In some embodiments of the present invention, during the curing process, Cu in the electroplating solution 2+The concentration of H₂SO₄ in the electroplating solution is 45 g / L to 80 g / L (e.g., 45 g / L, 50 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, or 80 g / L), the concentration of H₂SO₄ in the electroplating solution is 130 g / L to 160 g / L (e.g., 130 g / L, 140 g / L, 150 g / L, 155 g / L, or 160 g / L), the temperature of the electroplating solution is 35℃ to 50℃ (e.g., 30℃, 40℃, 45℃, or 50℃), the electrode distance is 60 mm, and the current density used is 3400 A / m. 2 The curing time is 5 to 10 seconds (preferably, the curing time is 8 seconds).

[0106] In some embodiments of the present invention, during the zinc plating process, the Zn in the electroplating solution... 2+ The concentration of the electroplating solution is 2.0 g / L to 4.0 g / L (e.g., 2.0 g / L, 2.5 g / L, 3.0 g / L, or 4.0 g / L), the concentration of potassium pyrophosphate is 35 g / L to 55 g / L (e.g., 35 g / L, 40 g / L, 45 g / L, 50 g / L, or 55 g / L), the pH is 10.8 to 11.8 (e.g., 10.8, 11, 11.2, 11.3, 11.4, 11.5, 11.6, or 11.8), the temperature of the electroplating solution is 35℃ to 55℃ (e.g., 35℃, 40℃, 45℃, 50℃, or 55℃), and the current density is 1000 A / m. 2 The electroplating time is 3 to 8 seconds (preferably 5 seconds).

[0107] In some embodiments of the present invention, during the chromium plating process, the concentration of CrO3 in the electroplating solution is 3.5 g / L to 3.8 g / L (e.g., 3.5 g / L, 3.6 g / L, 3.7 g / L, or 3.8 g / L), the concentration of NaOH is 22 g / L to 25 g / L (e.g., 22 g / L, 23 g / L, 24 g / L, or 25 g / L), the temperature of the electroplating solution is 25°C to 28°C (e.g., 25°C, 26°C, 27°C, or 28°C), the current is 60 A, the electroplating time is 3 to 8 seconds (preferably, the electroplating time is 5 seconds), and the electrode distance is 60 mm.

[0108] In this embodiment, after the copper foil rolling step is completed, the copper foil surface is subjected to zinc plating and chromium plating treatment. The process parameters are optimized to achieve an ultra-low profile while preventing oxidation and discoloration, thus improving its corrosion resistance. As a result, it does not oxidize or discolor during long-term storage at room temperature or within 60 minutes at a high temperature of 200°C. Here, ultra-low profile refers to low roughness.

[0109] In some embodiments of the present invention, the thickness of the rolled copper foil prepared by the rolling copper foil preparation method is 6 μm to 9 μm (e.g., 6 μm, 7 μm, 8 μm or 9 μm).

[0110] To further understand the present invention, the following detailed description of the preparation method of a 9μm red-coated rolled copper foil for lithium batteries provided by the present invention is provided in conjunction with embodiments.

[0111] Example 1

[0112] like Figure 1 As shown, a method for preparing a 9μm red-rolled copper foil specifically for lithium batteries includes the following steps:

[0113] (1) Base material preparation steps: Copper is smelted and processed sequentially through ingot casting, hot rolling, rough rolling, finish rolling and annealing to prepare a soft base material with a thickness of 150μm. The base material is red copper, that is, industrial pure copper, with a grade of C1100.

[0114] (2) Copper foil rolling steps: In order to ensure the appearance quality and product performance of copper foil, an annealing process is added in the middle, and the total rolling process is set to 7 rolling processes.

[0115] The first rolling pass has the following characteristics: the entry thickness is 150 μm, the exit thickness is 95 μm, the reduction rate is 36.7%, the total entry tension is 4700 N, the total exit tension is 5700 N, the rolling speed is 230 m / min, the rolling force is 380 kN, and the bending force is 2 MPa.

[0116] The second rolling process has the following parameters: entry thickness of 95μm, exit thickness of 70μm, reduction rate of 26.3%, total entry tension of 4590N, total exit tension of 3600N, rolling speed of 170m / min, rolling force of 380kN, and bending force of 2MPa.

[0117] Annealing process: Hold at 200℃ for 3 hours.

[0118] The third rolling process has the following parameters: entry thickness of 70 μm, exit thickness of 35 μm, reduction rate of 50%, total entry tension of 2100 N, total exit tension of 2000 N, rolling speed of 220 m / min, rolling force of 430 kN, and bending force of 2 MPa.

[0119] The fourth rolling process has the following characteristics: the entry thickness is 35μm, the exit thickness is 20.5μm, the reduction rate is 41.4%, the total entry tension is 1450N, the total exit tension is 1220N, the rolling speed is 350m / min, the rolling force is 470kN, and the bending force is 2MPa.

[0120] The fifth rolling pass has the following characteristics: the entry thickness is 20.5 μm, the exit thickness is 15 μm, the reduction rate is 26.8%, the total entry tension is 860 N, the total exit tension is 770 N, the rolling speed is 220 m / min, the rolling force is 420 kN, and the bending force is 2 MPa.

[0121] The sixth rolling pass has the following characteristics: the entry thickness is 15 μm, the exit thickness is 11.5 μm, the reduction rate is 23.3%, the total entry tension is 610 N, the total exit tension is 620 N, the rolling speed is 290 m / min, the rolling force is 400 kN, and the bending force is 2 MPa.

[0122] The seventh rolling pass has the following characteristics: the entry thickness is 11.5 μm, the exit thickness is 9 μm, the reduction rate is 21.7%, the total entry tension is 450 N, the total exit tension is 420 N, the rolling speed is 350 m / min, the rolling force is 460 kN, and the bending force is 2 MPa.

[0123] The final product was a 9.1 μm rolled copper foil.

[0124] (3) Redening treatment steps: chemical degreasing, electrolytic degreasing, pickling, roughening, curing, zinc plating, and chromium plating are carried out in sequence to finally obtain the rolled copper foil product with red treatment surface.

[0125] In the chemical degreasing treatment, the concentration of NaOH in the degreasing solution is 20 g / L to 30 g / L, the concentration of Na2CO3 is 30 g / L to 40 g / L, and the content of sodium silicate is 1% to 5%.

[0126] The electrolytic degreasing solution has the same composition as the chemical degreasing solution, and the operating temperature of the electrolytic degreasing solution is 30℃~60℃; the electrode distance is 60mm, and the current density used is 1800A / m. 2 .

[0127] In the pickling process, the concentration of H2SO4 in the pickling solution is 50 g / L to 100 g / L, and the temperature of the pickling solution is 30℃ to 40℃.

[0128] During the roughening process, Cu in the electroplating solution 2+ The concentration of H₂SO₄ in the electroplating solution is 12 g / L to 14 g / L, the concentration of H₂SO₄ in the solution is 230 g / L to 250 g / L, and the temperature of the electroplating solution is 30℃ to 40℃; the electrode distance is 60 mm, and the current density used is 1800 A / m. 2 The electroplating time is 8 seconds;

[0129] During the curing process, Cu in the electroplating solution 2+The concentration of H₂SO₄ in the electroplating solution is 45 g / L to 80 g / L, the concentration of H₂SO₄ in the electroplating solution is 130 g / L to 160 g / L, and the temperature of the electroplating solution is 35℃ to 50℃; the electrode distance is 60 mm, and the current density used is 3400 A / m. 2 The electroplating time is 8 seconds.

[0130] In the zinc plating process, the Zn in the electroplating solution 2+ The concentration of the electrolyte was 2.0 g / L to 4.0 g / L, the concentration of potassium pyrophosphate was 35 g / L to 55 g / L, the pH was 10.8 to 11.4, the temperature of the electroplating solution was 40℃ to 50℃, and the current density used was 1000 A / m. 2 The electroplating time is 5 seconds.

[0131] In the chromium plating process, the concentration of CrO3 in the electroplating solution is 3.5 g / L to 3.8 g / L, the concentration of NaOH is 22 g / L to 25 g / L, the temperature of the electroplating solution is 25℃ to 28℃, the current used is 60 A, the electrode distance is 60 mm, and the electroplating time is 5 seconds.

[0132] Finally, the finished rolled copper foil with a red-treated surface is obtained.

[0133] In this embodiment, after the copper foil is annealed at 200°C for 3 hours, the dislocations inside the grains are effectively recovered, and recrystallization also occurs to a certain extent. This phenomenon helps to improve the elongation of the material and helps to achieve thinner copper foil.

[0134] The rolled copper foil, after being tested by a universal testing machine, showed a tensile strength of 450 MPa and an elongation after fracture ≥1.1%. Its physicochemical properties met the requirements of GB / T 36146-2018 for rolled copper foil used in lithium-ion batteries. Furthermore, when the rolled copper foil was cut into sheet samples and placed in a high-temperature forced-air drying oven at 200℃ for 60 minutes, it showed a bright color and no oxidation or discoloration. The rolled copper foil, having met the performance requirements, can be used as a current collector in lithium-ion batteries. Its excellent physicochemical properties can reduce the possibility of punctures, effectively improving the safety and cycle life of lithium batteries.

[0135] Comparative Example 1

[0136] The only difference between Comparative Example 1 and Example 1 above is that the annealing process is omitted in the copper foil rolling process; the other steps are the same as those in Example 1.

[0137] The rolled copper foil products (bare foil) prepared in Example 1 and Comparative Example 1 were subjected to bending resistance tests using a bending resistance tester. The bending resistance was characterized by the number of bends required to break the copper foil. The bending resistance data (number of bends) of the rolled copper foil products in Example 1 and Comparative Example 1 are shown in Table 1.

[0138] Table 1 Comparison of flexural endurance (number of bends) between Example 1 and Comparative Example 1

[0139]

[0140] Where MD stands for Machine Direction, i.e., vertical direction. TD stands for transverse direction, i.e., horizontal direction.

[0141] Comparing the results of Example 1 and Comparative Example 1, it can be seen that Example 1 has more longitudinal bending times than Comparative Example 1, and Comparative Example 1 also has more transverse bending times. Therefore, compared with Comparative Example 1, the bending resistance of Example 1 is significantly improved. In other words, by adding an annealing process to the copper foil rolling process, the bending resistance of the rolled copper foil can be improved.

[0142] In addition, this invention also provides a rolled copper foil, which is prepared by the preparation method described in any of the above embodiments.

[0143] Furthermore, embodiments of the present invention also provide an application of the rolled copper foil prepared by the preparation method described in any of the above embodiments in the fields of lithium metal batteries, electrocatalysis, or sensing.

[0144] Preferably, rolled copper foil is used as a current collector in lithium batteries.

[0145] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for preparing rolled copper foil, characterized in that, include: The base material preparation steps are as follows: copper is smelted and processed, and then successively subjected to ingot casting, hot rolling, rough rolling, finish rolling and annealing to obtain the base material; the thickness of the base material is 80μm ~150μm; the base material is in a soft state and is made of pure copper. Copper foil rolling steps: The base material is rolled in 7 passes, with an annealing process added between the second and third rolling passes to prepare rolled copper foil with a thickness of 9μm~9.1μm; the reduction rate of the third rolling pass > the reduction rate of the fourth rolling pass > the reduction rate of the first rolling pass > the reduction rate of the second rolling pass > the reduction rate of the fifth rolling pass > the reduction rate of the sixth rolling pass > the reduction rate of the seventh rolling pass; in the annealing process, the temperature is maintained at 150~250℃ for 1~4 hours; The copper foil rolling process specifically includes the following steps: The first rolling process has a reduction rate of 35% to 38%, a total inlet tension of 4500N to 5000N, a total outlet tension of 5500N to 6000N, a rolling speed of 200m / min to 250m / min, a rolling force of 350kN to 400kN, and a bending force of 1 to 3MPa. The second rolling process has a reduction rate of 25% to 30%, a total inlet tension of 4500N to 5000N, a total outlet tension of 3500N to 4000N, a rolling speed of 150m / min to 200m / min, a rolling force of 350kN to 400kN, and a bending force of 1 to 3MPa. Annealing process; The third rolling process has a reduction rate of 48% to 52%, a total inlet tension of 2000N to 2200N, a total outlet tension of 2000N to 2200N, a rolling speed of 200m / min to 230m / min, a rolling force of 400kN to 450kN, and a bending force of 1 to 3MPa. The fourth rolling process: the reduction rate is 40% to 42%, the total inlet tension is 1100N to 1300N, the total outlet tension is 1300N to 1500N, the rolling speed is 330m / min to 350m / min, the rolling force is 450kN to 500kN, and the bending force is 1 to 3MPa. The fifth rolling process: the reduction rate is 25% to 28%, the total inlet tension is 800N to 1000N, the total outlet tension is 700N to 900N, the rolling speed is 200m / min to 230m / min, the rolling force is 400kN to 450kN, and the bending force is 1 to 3MPa. The sixth rolling process: the reduction rate is 22% to 25%, the total inlet tension is 600N to 650N, the total outlet tension is 600N to 650N, the rolling speed is 250m / min to 300m / min, the rolling force is 350kN to 400kN, and the bending force is 1 to 3MPa. The seventh rolling process has a reduction rate of 20% to 22%, a total inlet tension of 400N to 500N, a total outlet tension of 400N to 500N, a rolling speed of 350m / min to 400m / min, a rolling force of 450kN to 500kN, and a bending force of 1 to 3MPa.

2. The method for preparing rolled copper foil according to claim 1, characterized in that, Following the copper foil rolling step, the process further includes: Surface treatment steps: The rolled copper foil is subjected to surface treatment; the surface treatment steps include reddening treatment, blackening treatment or graying treatment.

3. The method for preparing rolled copper foil according to claim 2, characterized in that, The surface treatment steps include a reddening process; In the reddening process, chemical degreasing, electrolytic degreasing, pickling, roughening, curing, zinc plating, and chromium plating are performed sequentially to form a red-treated surface on the rolled copper foil. In the chemical degreasing process, the concentration of NaOH in the chemical degreasing solution is 20 g / L to 30 g / L, the concentration of Na2CO3 is 30 g / L to 40 g / L, and the content of sodium silicate is 1% to 5%. In the electrolytic degreasing process, the electrolytic degreasing solution has the same composition as the chemical degreasing solution. The working temperature of the electrolytic degreasing solution is 30℃~60℃, the electrode distance is 60mm, and the current density is 1800A / m². In the roughening process, Cu in the electroplating solution 2+ The concentration of H2SO4 in the electroplating solution is 12 g / L to 14 g / L, the concentration of H2SO4 in the electroplating solution is 230 g / L to 250 g / L, the temperature of the electroplating solution is 30℃ to 40℃, the electrode distance is 60 mm, the current density is 1800 A / m², and the roughening time is 5 to 10 seconds. In the curing process, Cu in the electroplating solution 2+ The concentration of H2SO4 in the electroplating solution is 45 g / L to 80 g / L, the concentration of H2SO4 in the electroplating solution is 130 g / L to 160 g / L, the temperature of the electroplating solution is 35℃ to 50℃, the electrode distance is 60 mm, the current density used is 3400 A / m², and the curing time is 5 to 10 seconds. In the zinc plating process, the Zn in the electroplating solution 2+ The concentration of the solution is 2.0 g / L to 4.0 g / L, the concentration of potassium pyrophosphate is 35 g / L to 55 g / L, the pH is 10.8 to 11.8, the temperature of the electroplating solution is 35℃ to 55℃, the current density is 1000 A / m², and the electroplating time is 3 to 8 seconds. In the chromium plating process, the concentration of CrO3 in the electroplating solution is 3.5 g / L to 3.8 g / L, the concentration of NaOH is 22 g / L to 25 g / L, the temperature of the electroplating solution is 25℃ to 28℃, the current is 60 A, the electroplating time is 3 to 8 seconds, and the electrode distance is 60 mm.

4. A rolled copper foil prepared by any one of claims 1-3.

5. An application of a rolled copper foil prepared by any one of claims 1-3 in the fields of lithium metal batteries, electrocatalysis, or sensing.

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