Electrolytic copper foil and preparation method thereof, printed circuit board, negative current collector and battery

Abstract

The invention relates to an electrolytic copper foil and a preparation method thereof, a printed circuit board, a negative electrode current collector and a battery, the electrolytic copper foil is of a layer-by-layer structure and comprises a columnar crystal layer and blocky crystal layers located on the two sides of the columnar crystal layer, the grain size of the columnar crystal layer is 60 nm to 250 nm, and the grain size of the blocky crystal layers is 350 nm to 750 nm. The electrolytic copper foil with the layer-by-layer structure can give consideration to tensile strength, ductility and low warping degree after high-temperature annealing, and the bending resistance is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of electrolytic copper foil, and in particular to an electrolytic copper foil and a preparation method thereof, a printed circuit board, a negative electrode current collector and a battery. Background Art

[0002] Electrolytic copper foil is a high-purity, highly conductive, and ductile metal foil widely used in printed circuit boards, lithium-ion batteries, semiconductor packaging, and high-frequency copper-clad laminates. Electrolytic copper foil is produced by utilizing the redox reaction during electrolysis, where copper ions in the electrolyte receive electrons at the cathode, reducing them to elemental copper. However, current electrolytic copper foil is prone to warping after being removed from the cathode roller, and its tensile strength and ductility are suboptimal after high-temperature annealing. Summary of the Invention

[0003] Based on this, it is necessary to provide an electrolytic copper foil and its preparation method, a printed circuit board, a negative electrode current collector and a battery that can take into account tensile strength, ductility and low warpage after high temperature annealing.

[0004] In a first aspect of the present application, an electrolytic copper foil is provided, which has a layered structure, including a columnar crystal layer and a block crystal layer located on both sides of the columnar crystal layer, the grain size of the columnar crystal layer is 60 nm~250 nm, and the grain size of the block crystal layer is 350 nm~750 nm.

[0005] The electrolytic copper foil with the above-mentioned layered structure has a columnar crystal layer and a block crystal layer located on both sides of the columnar crystal layer. The grain size of the columnar crystal layer is 60 nm~250 nm, and the grain size of the block crystal layer is 350 nm~750 nm. The electrolytic copper foil with this layered structure can take into account the tensile strength, ductility and low warpage after high-temperature annealing, and the bending resistance of the electrolytic copper foil is significantly improved.

[0006] In the above-mentioned electrolytic copper foil, the grains of the columnar crystal layer grow in a preferred orientation. The grain size of the columnar crystal layer is relatively small, ranging from 60nm to 250nm, with a large number of grains, a large grain boundary density, and a high tensile strength. The block crystal layer located on both sides of the columnar crystal layer does not have an obvious preferred orientation. The grains of the block crystal layer are almost equal in size in three-dimensional space. The grain size of the block crystal layer is 350nm to 750nm, which is larger than the grain size of the columnar crystal layer. The number of grains per unit volume of the block crystal layer is much smaller than that of the columnar crystal layer. The block crystal layer has excellent ductility and bending resistance. The columnar crystal layer and the block crystal layers on both sides cooperate with each other to synergistically improve the tensile strength, elongation and bending resistance of the electrolytic copper foil after high-temperature annealing. The layered structure of the above-mentioned electrolytic copper foil makes the internal stress on both sides of the electrolytic copper foil relatively balanced, and the difference in internal stress on both sides of the electrolytic copper foil is small. Even after high-temperature annealing, due to the small degree of stress release, the degree of tensile attenuation is also small, thereby reducing the warping.

[0007] In some embodiments, the columnar crystal layer satisfies at least one of the following conditions:

[0008] (1) In the columnar crystal layer, the proportion of low-angle grain boundaries less than or equal to 10° is greater than 60%;

[0009] (2) The grain size of the columnar crystal layer is 100 nm to 200 nm;

[0010] (3) The ratio of the major axis to the minor axis of the grains in the columnar crystal layer is greater than or equal to 3 and less than or equal to 7.

[0011] In some embodiments, the crystal texture of the columnar crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 30% to 70%; and / or,

[0012] The ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 20% to 50%; and / or,

[0013] The ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 5% to 20%; and / or,

[0014] The variation of the spacing between the (111) crystal plane, the (200) crystal plane and the (220) crystal plane relative to the standard sample is 1×10 -3 ~5×10 -3 .

[0015] In some embodiments, the bulk crystal layer satisfies at least one of the following conditions:

[0016] (1) In the blocky crystal layer, the proportion of high-angle grain boundaries greater than or equal to 15° is greater than or equal to 65%;

[0017] (2) The grain size of the bulk crystal layer is 500 nm to 700 nm;

[0018] (3) The ratio of the major axis to the minor axis of the grains in the blocky crystal layer is less than or equal to 1.4.

[0019] In some embodiments, the crystal texture of the block crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 20%-40%; and / or,

[0020] The ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 20% to 45%; and / or,

[0021] The ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 10% to 30%; and / or,

[0022] In the block crystal layer, the variation of the interplanar spacings of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane relative to the standard sample is 2×10 -4 ~7×10 -4 .

[0023] In some embodiments, the electrolytic copper foil satisfies at least one of the following conditions:

[0024] (1) The thickness of the electrolytic copper foil is 9 μm to 35 μm, and the thickness of the columnar crystal layer is 5 μm to 25 μm;

[0025] (2) The Poisson's ratio of the electrolytic copper foil is 0.35-0.37;

[0026] (3) The internal stress difference between the two sides of the electrolytic copper foil is less than or equal to 25 MPa;

[0027] (4) The average line height Rc of the contour unit of the matte surface of the electrolytic copper foil is less than or equal to 3 μm;

[0028] (5) The tensile strength of the electrolytic copper foil after annealing at 180°C for 1 hour is greater than or equal to 450 MPa;

[0029] (6) The elongation of the electrolytic copper foil after annealing at 180°C for 1 hour is greater than or equal to 10%;

[0030] (7) The warpage of the electrolytic copper foil after annealing at 180°C for 1 hour is less than or equal to 4 mm;

[0031] (8) The electrolytic copper foil has a bending resistance of greater than or equal to 800 times after annealing at 180°C for 1 hour.

[0032] A second aspect of the present application provides a method for preparing an electrolytic copper foil, comprising the following steps:

[0033] forming a bulk crystal layer by electroplating using a first electroplating solution, wherein the additive of the first electroplating solution includes a calixarene derivative;

[0034] Using a second electroplating solution to electroplating on one side of the block crystal layer to form a columnar crystal layer, the second electroplating solution having an additive including an organic sulfur-containing sulfonate;

[0035] A third electroplating solution is used to electroplating on one side of the columnar crystal layer away from the block crystal layer to form a block crystal layer on the other side; the third electroplating solution includes a calixarene derivative.

[0036] In some embodiments, the calixarene derivative comprises at least one of 4-sulfonated thia[4]arene sodium salt, 4-sulfonated thia[4]arene potassium salt, 4-hydroxythia[4]arene sodium salt, calix[4]arene sulfonic acid sodium salt, and p-sulfonated thia[4]arene sodium salt; and / or,

[0037] The organic sulfur-containing sulfonate includes at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, and sodium thiazoline disulfide propane sulfonate.

[0038] In some embodiments, the mass concentration of the sodium salt of 4-sulfonated thia[4]arene in the first electroplating solution is 1 mg / L to 10 mg / L; and / or,

[0039] The mass concentration of the sodium polydisulfide propane sulfonate in the second electroplating solution is 3 mg / L to 15 mg / L; and / or,

[0040] The mass concentration of the sodium salt of 4-sulfonated thia[4]arene in the third electroplating solution is 1 mg / L to 10 mg / L.

[0041] In some embodiments, the additives of the first electroplating solution further include at least two of cerium sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol; and / or,

[0042] The additives of the second electroplating solution further include at least two of butynediol, polyethylene glycol, collagen and hydroxyethyl cellulose; and / or,

[0043] The additives of the third electroplating solution further include at least two of cerium sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol.

[0044] In some embodiments, the mass concentration of the ceric sulfate in the first electroplating solution and the third electroplating solution is 5 mg / L to 10 mg / L; and / or,

[0045] The mass concentration of the hexadecyltrimethylammonium chloride in the first electroplating solution and the third electroplating solution is 10 mg / L to 100 mg / L; and / or,

[0046] The mass concentration of the polypropylene glycol in the first electroplating solution and the third electroplating solution is 0.5 g / L to 5 g / L; and / or,

[0047] The mass concentration of the butynediol in the second electroplating solution is 10 mg / L to 50 mg / L; and / or,

[0048] The mass concentration of the polyethylene glycol in the second electroplating solution is 0.5 g / L to 5 g / L; and / or,

[0049] The mass concentration of the collagen in the second electroplating solution is 10 mg / L to 50 mg / L; and / or,

[0050] The mass concentration of the hydroxyethyl cellulose in the second electroplating solution is 5 mg / L to 50 mg / L.

[0051] The third aspect of the present application provides a printed circuit board, comprising the electrolytic copper foil described in the first aspect, or the electrolytic copper foil prepared by the preparation method described in the second aspect.

[0052] The fourth aspect of the present application provides a negative electrode current collector, comprising the electrolytic copper foil described in the first aspect, or the electrolytic copper foil prepared by the preparation method described in the second aspect.

[0053] The fifth aspect of the present application provides a battery comprising the negative electrode current collector described in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the structure of electrolytic copper foil.

[0055] Figure 2 It is an application of electrolytic copper foil (copper clad laminate).

[0056] Figure 3 Another application of electrolytic copper foil (lithium battery negative electrode).

[0057] Description of reference numerals:

[0058] 10. Electrolytic copper foil; 101. Block crystal layer; 102. Columnar crystal layer; 103. Roughening layer; 20. Copper clad laminate; 201. Insulating substrate; 30. Lithium-ion battery negative electrode; 301. Silicon-carbon negative electrode slurry layer. DETAILED DESCRIPTION

[0059] To facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments. Preferred embodiments of the present application are provided herein. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0061] Electrolytic copper foil utilizes the redox reaction during the electrolysis process, whereby copper ions in the electrolyte gain electrons at the cathode, reducing them to elemental copper. Currently, manufacturers primarily use foil-making machines to produce electrolytic copper foil. These machines consist of four main components: an electrolytic cell, cathode rollers, anode plates, and an external circuit.

[0062] The crystal structure of electrolytic copper foil is primarily influenced by the nucleation and growth mechanisms, the electric field and ion concentration distribution, the cathode roller surface morphology, the convection and agitation of the electrolyte, and the composition of electrolyte additives. This results in inconsistencies in grain size, crystal orientation, crystal defects, and the number of grain boundaries between the surface of the electrolytic copper foil closest to the cathode roller (the smooth side) and the surface farther from the cathode roller (the matte side). Typically, the grain size on the smooth side of the electrolytic copper foil is smaller than that on the matte side, and the number of grains and grain boundaries is also significantly greater. Because small-grained copper foil has many grain boundaries and irregular atomic arrangement at the grain boundaries, it hinders dislocation motion, resulting in relatively high tensile strength and relatively poor ductility. Small-grained copper foil struggles to release stress through inter-grain slip and deformation, leading to stress concentration and cracking when bent. Copper foil with large grains, on the other hand, exhibits relatively low tensile strength but better ductility and less stress concentration. It is precisely because of the significant difference in crystal structure between the smooth and matte sides of the electrolytic copper foil that the compressive stress on the smooth and matte sides is unbalanced, resulting in natural warping of the electrolytic copper foil after it is peeled off the cathode roller. These warpings will cause trouble to the production of downstream printed circuit boards. Moreover, the tensile strength and ductility of the electrolytic copper foil after high-temperature annealing need to be improved.

[0063] Based on this, see Figure 1 In one embodiment of the present application, an electrolytic copper foil 10 is provided. The electrolytic copper foil 10 has a layered structure, including a columnar crystal layer 102 and a block crystal layer 101 located on both sides of the columnar crystal layer 102. The grain size of the columnar crystal layer 102 is 60 nm~250 nm, and the grain size of the block crystal layer 101 is 350 nm~750 nm.

[0064] The layered electrolytic copper foil has a columnar crystal layer flanked by blocky crystal layers. The columnar crystal layer has a grain size of 60 nm to 250 nm, while the blocky crystal layer has a grain size of 350 nm to 750 nm. This layered structure balances tensile strength, ductility, and low warpage after high-temperature annealing, significantly improving the foil's bending resistance. After annealing at 180°C for one hour, the foil maintains high tensile strength (>450 MPa) and high elongation (>10%), with minimal warpage (<4 mm).

[0065] In the above-mentioned electrolytic copper foil, the grains of the columnar crystal layer grow in a preferred orientation. The grain size of the columnar crystal layer is relatively small, ranging from 60nm to 250nm, with a large number of grains, a large grain boundary density, and a high tensile strength. The block crystal layer located on both sides of the columnar crystal layer does not have an obvious preferred orientation. The grains of the block crystal layer are almost equal in size in three-dimensional space. The grain size of the block crystal layer is 350nm to 750nm, which is larger than the grain size of the columnar crystal layer. The number of grains per unit volume of the block crystal layer is much smaller than that of the columnar crystal layer. The block crystal layer has excellent ductility and bending resistance. The columnar crystal layer and the block crystal layers on both sides cooperate with each other to synergistically improve the tensile strength, elongation and bending resistance of the electrolytic copper foil after high-temperature annealing. The layered structure of the above-mentioned electrolytic copper foil makes the internal stress on both sides of the electrolytic copper foil relatively balanced, and the difference in internal stress on both sides of the electrolytic copper foil is small. Even after high-temperature annealing, due to the small degree of stress release, the degree of tensile attenuation is also small, thereby reducing the warping.

[0066] Understandably, columnar crystals refer to crystals that preferentially grow along a specific direction during growth, resulting in a large aspect ratio and columnar, elongated crystal structure. Blocky crystals (also known as equiaxed crystals) are crystals with a relatively uniform growth rate in all directions, resulting in a nearly equiaxed structure with no apparent preferred growth direction.

[0067] It can be understood that the above-mentioned electrolytic copper foil is an electrolytic copper foil with a bimodal crystal structure.

[0068] The above-mentioned grain size is the equivalent circular diameter of the grain.

[0069] The grain size can be measured using the following test method: Electron backscatter diffraction (EBSD) testing of the copper foil cross section is performed at a magnification of 1500 times using a Zeiss Sigma300 scanning electron microscope equipped with an Oxford Instruments Symmetry S3 detector. The Oxford Instruments AZtecCrystal analysis software automatically provides the test results.

[0070] As an example, the grain size of the columnar crystal layer can be 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, 155nm, 160nm, 165nm, 170nm, 175nm, 180nm, 185nm, 190nm, 195nm, 200nm, 205nm, 210nm, 215nm, 220nm, 225nm, 230nm, 235nm, 240nm, 245nm and 250nm, or it can be within the range formed by any two of the above point values ​​as end values.

[0071] Furthermore, the grain size of the columnar crystal layer is 100 nm to 200 nm.

[0072] As an example, the grain size of the bulk crystal layer can be 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, 410nm, 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, 480nm, 490nm, 500nm, 510nm, 520nm, 530nm, 540nm, 550nm, 560nm, 570nm, 580nm, 590nm, 600nm, 610nm, 620nm, 630nm, 640nm, 650nm, 660nm, 670nm, 680nm, 690nm, 700nm, 710nm, 720nm, 730nm, 740nm and 750nm, or it can be within the range formed by any two of the above point values ​​as end values.

[0073] Furthermore, the grain size of the bulk crystal layer is 500nm~700nm.

[0074] In some embodiments, the thickness of the electrolytic copper foil is 9 μm to 35 μm, and the thickness of the columnar crystal layer is 5 μm to 25 μm.

[0075] As an example, the thickness of the electrolytic copper foil can be 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm and 35μm, or it can be within the range formed by any two of the above point values ​​as end values.

[0076] As an example, the thickness of the columnar crystal layer is 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, and 25μm, or it can be within the range formed by any two of the above point values ​​as end values.

[0077] Furthermore, the thickness of the electrolytic copper foil is 12 μm to 18 μm, and the thickness of the columnar crystal layer is 6 μm to 12 μm.

[0078] In some embodiments, the bulk crystal layer has a thickness of 2 μm to 5 μm.

[0079] In some embodiments, in the columnar crystal layer, the proportion of low-angle grain boundaries less than or equal to 10° is greater than 60%.

[0080] The percentage of small-angle grain boundaries is the ratio of the area covered by small-angle grain boundaries to the total area of ​​the analysis region. The above-mentioned percentage of small-angle grain boundaries is obtained based on the results of EBSD (electron backscatter diffraction) test, using Oxford Instruments AZtecCrystal analysis software to analyze the orientation difference of grains.

[0081] Furthermore, in the columnar crystal layer, the proportion of low-angle grain boundaries less than or equal to 10° is greater than 60% and less than 80%.

[0082] In some embodiments, a ratio of a major axis to a minor axis of grains in the columnar crystal layer is greater than or equal to 3 and less than or equal to 7.

[0083] Furthermore, the columnar crystals grow along the thickness direction, the grain size is 60 nm to 250 nm, and the ratio of the major axis to the minor axis is greater than or equal to 3 and less than or equal to 7.

[0084] In some embodiments, the crystal texture of the columnar crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 30% to 70%.

[0085] It can be understood that the number of crystal planes is the number of peaks presented in the X-ray diffraction pattern. The XRD pattern of copper foil usually shows three crystal planes: (111) crystal plane, (200) crystal plane and (220) crystal plane.

[0086] It can be understood that the crystal texture of the columnar crystal layer includes (111) crystal plane, (200) crystal plane, and (220) crystal plane. Each crystal plane has a corresponding texture coefficient. The texture coefficient TC (hkl)Define the following formula:

[0087]

[0088] Among them, I (hkl) is the measured X-ray diffraction intensity of the crystal plane (hkl); I 0(hkl) is the X-ray diffraction intensity of the same crystal plane of the standard non-textured sample; i is the ordinal number (here 1, 2 or 3), and N is the total number of crystal planes counted (here 3).

[0089] In some embodiments, the crystal texture of the columnar crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 20% to 50%.

[0090] In some embodiments, the crystal texture of the columnar crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 5% to 20%.

[0091] In some embodiments, in the columnar crystal layer, the change in the interplanar spacing of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane relative to the standard sample is 1.10 -3 ~5.10 -3 .

[0092] Understandably, based on the XRD (X-ray diffraction) results, the Bragg equation is used to calculate the change in the interplanar spacing relative to the standard sample. , the change in interplanar spacing Define the following formula:

[0093]

[0094] Among them, d (hkl) represents the interplanar spacing of the (hkl) crystal plane of the sample to be tested, d 0(hkl) represents the interplanar spacing of the (hkl) crystal plane of the standard sample, d (hkl)— d 0(hkl) The absolute value of the ratio of the difference to the interplanar spacing of the standard sample is used to obtain the variation. , the change in the interplanar spacing Dimensionless.

[0095] In some embodiments, in the bulk crystal layer, the proportion of high-angle grain boundaries greater than or equal to 15° is greater than 65%.

[0096] Furthermore, the proportion of high-angle grain boundaries greater than or equal to 15° is greater than 65% and less than 80%.

[0097] The percentage of high-angle grain boundaries is the ratio of the area covered by high-angle grain boundaries to the total area of ​​the analyzed region. The percentage of low-angle grain boundaries is obtained based on the results of EBSD (electron backscatter diffraction) and the orientation difference analysis of the grains using Oxford Instruments AZtecCrystal analysis software.

[0098] In some embodiments, the major axis to minor axis ratio of the grains of the bulk crystal layer is less than or equal to 1.4.

[0099] Furthermore, the grain size of the block crystal layer is 350 nm to 750 nm, and the ratio of the major axis to the minor axis of the grain is less than or equal to 1.4.

[0100] In some embodiments, the crystal texture of the block crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 20% to 40%.

[0101] In some embodiments, the crystal texture of the block crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 20% to 45%.

[0102] In some embodiments, the crystal texture of the block crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 10% to 30%.

[0103] In some embodiments, in the bulk crystal layer, the change in the interplanar spacing of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane relative to the standard sample is 2×10 -4 ~7×10 -4 .

[0104] In some embodiments, the Poisson's ratio of the electrolytic copper foil is 0.35-0.37.

[0105] It can be understood that the Poisson's ratio is the absolute value of the ratio of the transverse strain generated by the axial stress to the axial strain when the electrolytic copper foil is axially stretched.

[0106] In some embodiments, the average height Rc of the contour units of the matte surface (or the surface to be treated) of the electrolytic copper foil is less than or equal to 3 μm.

[0107] In some embodiments, the tensile strength of the electrolytic copper foil after annealing at 180° C. for 1 hour is greater than or equal to 450 MPa.

[0108] Furthermore, the tensile strength of the electrolytic copper foil after annealing at 180°C for 1 hour is 450 MPa~600 MPa.

[0109] In some embodiments, the elongation of the electrolytic copper foil after annealing at 180° C. for 1 hour is greater than or equal to 10%.

[0110] Furthermore, the elongation of the electrolytic copper foil after annealing at 180° C. for 1 hour is 10% to 20%.

[0111] In some embodiments, the warpage of the electrolytic copper foil after annealing at 180° C. for 1 hour is less than or equal to 4 mm.

[0112] Furthermore, the warpage of the electrolytic copper foil after annealing at 180°C for 1 hour is 1 mm to 4 mm.

[0113] In some embodiments, the number of bending resistance of the electrolytic copper foil after annealing at 180° C. for 1 hour is greater than or equal to 800. It is understood that the bending resistance performance is obtained by referring to the IPC-TM-650 test standard.

[0114] Furthermore, the electrolytic copper foil can withstand 800 to 1000 bending cycles after annealing at 180°C for 1 hour.

[0115] In some embodiments, the internal stress difference between two sides of the electrolytic copper foil is less than or equal to 25 MPa.

[0116] Furthermore, the internal stress difference between the two sides of the electrolytic copper foil is 10 MPa ~20 MPa.

[0117] It can be understood that the internal stress σ of the electrolytic copper foil can be calculated according to the substrate bending method using the following formula (3):

[0118]

[0119] Among them, E s , v s , t s are the elastic modulus, Poisson's ratio and thickness of the substrate respectively; t f is the thickness of the copper layer, R is the radius of curvature of the substrate after the copper layer is deposited on the substrate, and R0 is the radius of curvature of the substrate before the copper layer is deposited on the substrate.

[0120] A second aspect of the present application provides a method for preparing an electrolytic copper foil, comprising the following steps:

[0121] S1: electroplating a bulk crystal layer using a first electroplating solution, wherein the additive of the first electroplating solution includes a calixarene derivative;

[0122] S2: electroplating a columnar crystal layer on one side of the block crystal layer using a second electroplating solution, wherein the additive of the second electroplating solution includes an organic sulfur-containing sulfonate;

[0123] S3: using a third electroplating solution to electroplating on one side of the columnar crystal layer away from the block crystal layer to form a block crystal layer on the other side; the third electroplating solution includes a calixarene derivative.

[0124] The above preparation method uses layered electroplating to sequentially electroplate a blocky crystal layer on one side, a columnar crystal layer, and a blocky crystal layer on the other side. The additive calixarene derivatives are introduced into the first and third electroplating solutions. The calixarene derivatives have a rigid structure, which causes copper grains to align along the edges of the rigid structure of the aromatics, weakening the vertical orientation of the copper grains, inhibiting the preferred orientation growth of the copper grains, and reducing cathodic polarization, promoting the formation of blocky crystal layers. The cathode polarization is enhanced by introducing an organic sulfur-containing sulfonate into the second electroplating solution, promoting the preferred orientation growth of copper grains and further promoting the formation of columnar crystal layers. The electrolytic copper foil obtained by the above preparation method has excellent tensile strength, ductility, and bending resistance after high-temperature annealing, and has low warpage after high-temperature annealing.

[0125] In some embodiments, the calixarene derivative includes at least one of 4-sulfonated thia[4]arene sodium salt, 4-sulfonated thia[4]arene potassium salt, 4-hydroxythia[4]arene sodium salt, calix[4]arene sulfonic acid sodium salt, and p-sulfonated thia[4]arene sodium salt.

[0126] In some embodiments, the organic sulfur-containing sulfonate includes at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, and sodium thiazolinyl disulfide propane sulfonate.

[0127] In some embodiments, the calixarene derivative is sodium salt of 4-sulfonated thia[4]arene, and the organic sulfur-containing sulfonate is sodium polydisulfide dipropane sulfonate. By introducing the additive sodium salt of 4-sulfonated thia[4]arene into the first electroplating solution and the third electroplating solution, the sodium salt of 4-sulfonated thia[4]arene has a rigid structure, and the sodium salt of 4-sulfonated thia[4]arene promotes the arrangement of copper grains along the edges of the rigid structure of the aromatic hydrocarbon, weakens the vertical orientation of the copper grains, inhibits the preferred orientation growth of the copper grains, reduces the cathode polarization, and promotes the formation of block crystal layers; by introducing sodium polydisulfide dipropane sulfonate into the second electroplating solution to enhance the cathode polarization, promote the preferred orientation growth of the copper grains, and further promote the formation of columnar crystal layers, further improve the tensile strength, ductility and bending resistance of the electrolytic copper foil after high-temperature annealing, and further reduce the warpage of the electrolytic copper foil after high-temperature annealing.

[0128] In some embodiments, the mass concentration of the calixarene derivative in the first electroplating solution is 1 mg / L to 10 mg / L.

[0129] Furthermore, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the first electroplating solution is 1 mg / L to 10 mg / L.

[0130] As an example, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the first electroplating solution can be 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L and 10 mg / L, or it can be within the range formed by any two of the above point values ​​as end values.

[0131] Furthermore, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the first electroplating solution is 2 mg / L to 8 mg / L. At this mass concentration, 4-sulfonated thia[4]arene sodium salt can further improve the tensile strength, elongation, and bending resistance of the electrolytic copper foil after high-temperature annealing.

[0132] In some embodiments, the mass concentration of the organic sulfur-containing sulfonate in the second electroplating solution is 3 mg / L to 15 mg / L.

[0133] Furthermore, the mass concentration of sodium polydipropylene glycol disulfide sulfonate in the second electroplating solution is 3 mg / L to 15 mg / L.

[0134] As an example, the mass concentration of sodium polydipropylene glycol sulfonate in the second plating solution can be 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, 11 mg / L, 12 mg / L, 13 mg / L, 14 mg / L and 15 mg / L, or it can be within the range formed by any two of the above point values ​​as end values.

[0135] Furthermore, the mass concentration of sodium polydipropylene glycol disulfide sulfonate in the second electroplating solution is 5 mg / L to 8 mg / L. At this mass concentration, sodium polydipropylene glycol disulfide sulfonate can further improve the tensile strength, elongation, and bending resistance of the electrolytic copper foil after high-temperature annealing.

[0136] In some embodiments, the mass concentration of the calixarene derivative in the third electroplating solution is 1 mg / L to 10 mg / L.

[0137] Furthermore, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the third electroplating solution is 1 mg / L to 10 mg / L.

[0138] As an example, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the third electroplating solution can be 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L and 10 mg / L, or it can be within the range formed by any two of the above point values ​​as end values.

[0139] Furthermore, the mass concentration of 4-sulfonated thia[4]arene sodium salt in the third electroplating solution is 2 mg / L to 8 mg / L.

[0140] In some embodiments, the additives of the first electroplating solution further include at least two of ceric sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol.

[0141] Furthermore, the additives of the first electroplating solution include three or four of cerium sulfate, hexadecyltrimethylammonium chloride, polypropylene glycol and sodium salt of 4-sulfonated thia[4]arene.

[0142] In some embodiments, the additives of the second electroplating solution further include at least two of butynediol, polyethylene glycol, collagen, and hydroxyethyl cellulose.

[0143] Furthermore, the additives of the second electroplating solution include at least three of butynediol, polyethylene glycol, sodium polydisulfide dipropane sulfonate, collagen and hydroxyethyl cellulose.

[0144] In some embodiments, the additives of the third electroplating solution further include at least two of cerium sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol.

[0145] Furthermore, the additives of the third electroplating solution include three or four of cerium sulfate, hexadecyltrimethylammonium chloride, polypropylene glycol and sodium salt of 4-sulfonated thia[4]arene.

[0146] In some embodiments, the mass concentration of ceric sulfate in the first electroplating solution and the third electroplating solution is 5 mg / L to 10 mg / L.

[0147] In some embodiments, the mass concentration of hexadecyltrimethylammonium chloride in the first electroplating solution and the third electroplating solution is 10 mg / L to 100 mg / L.

[0148] In some embodiments, the mass concentration of polypropylene glycol in the first plating solution and the third plating solution is 0.5 g / L to 5 g / L.

[0149] In some embodiments, the mass concentration of butynediol in the second electroplating solution is 10 mg / L to 50 mg / L.

[0150] In some embodiments, the mass concentration of polyethylene glycol in the second electroplating solution is 0.5 g / L to 5 g / L.

[0151] In some embodiments, the mass concentration of collagen in the second electroplating solution is 10 mg / L to 50 mg / L.

[0152] In some embodiments, the mass concentration of hydroxyethyl cellulose in the second plating solution is 5 mg / L to 50 mg / L.

[0153] In some embodiments, the first electroplating solution includes copper ions, concentrated sulfuric acid, chloride ions, additives and water, wherein the additives include a combination of three or more of ceric sulfate, hexadecyltrimethylammonium chloride, polypropylene glycol, and sodium salt of 4-sulfonated thia[4]arene.

[0154] In some embodiments, the mass concentration of each additive in the first electroplating solution is as follows: 5 mg / L to 10 mg / L of cerium sulfate, 10 mg / L to 100 mg / L of hexadecyltrimethylammonium chloride, 0.5 g / L to 5 g / L of polypropylene glycol, and 1 mg / L to 10 mg / L of sodium 4-sulfonated thia[4]arene. This additive concentration is beneficial for reducing cathode polarization, while avoiding the hydrolysis of copper ions, reducing nucleation density and promoting grain merging, inhibiting the preferred orientation growth of grains, and further promoting the formation of blocky crystal layers.

[0155] In some embodiments, in S1, electroplating is performed using the DSA titanium material as an anode and the polished titanium plate as a cathode.

[0156] In some embodiments, in S1, the copper ion mass concentration in the first electroplating solution is 60 g / L-80 g / L, the chloride ion mass concentration is 10 mg / L-50 mg / L, and the pH value is 1.5-3.

[0157] In some embodiments, in S1, the current density of the electroplating is 2A / dm 2 ~5A / dm 2 , the plating solution temperature is 35℃~50℃. Under these plating conditions, it is beneficial to reduce cathode polarization, avoid hydrolysis of copper ions, reduce nucleation density and promote grain merging, inhibit the preferred orientation growth of grains, and further promote the formation of blocky crystal layers.

[0158] In some embodiments, the second electroplating solution includes copper ions, sulfuric acid, chloride ions, additives, and water, wherein the additives include at least three of butynediol, polyethylene glycol, sodium polydisulfide dipropane sulfonate, collagen, and hydroxyethyl cellulose.

[0159] In some embodiments, the concentrations of the additives in the second electroplating solution are as follows: butynediol 10 mg / L to 50 mg / L, polyethylene glycol 0.5 g / L to 5 g / L, sodium polydisulfide bis(propylene sulfonate) 3 mg / L to 15 mg / L, collagen 10 mg / L to 50 mg / L, and hydroxyethyl cellulose 5 mg / L to 50 mg / L.

[0160] In some embodiments, in S2, electroplating is performed using the DSA titanium material as an anode and the polished titanium plate as a cathode.

[0161] In some embodiments, in S2, the copper ion mass concentration in the second electroplating solution is 80 g / L~100 g / L, the sulfuric acid mass concentration is 130 g / L~180 g / L, and the chloride ion mass concentration is 5 mg / L~20 mg / L.

[0162] In some embodiments, in S2, the current density of the electroplating is 5A / dm 2 ~10A / dm 2 , the temperature of the second electroplating solution is 25℃~50℃.

[0163] In some embodiments, in S3 , the third electroplating solution is the same as the first electroplating solution.

[0164] In some embodiments, in S3 , the electroplating conditions for electroplating using the third electroplating solution are the same as the electroplating conditions for electroplating using the first electroplating solution.

[0165] The type of additives in the third electroplating solution may be the same as or different from that in the first electroplating solution.

[0166] The third aspect of the present application provides a printed circuit board, comprising the electrolytic copper foil of the first aspect, or the electrolytic copper foil prepared by the preparation method of the second aspect.

[0167] In some embodiments, the electrolytic copper foil is surface-treated and then pressed with a prepreg to obtain a single-sided or double-sided copper-clad laminate, which is then used to prepare a printed circuit board.

[0168] Furthermore, the surface treatment includes any one of roughening, passivation, rust prevention, and silane coating, or a combination thereof.

[0169] Furthermore, the prepreg includes thermoplastic and thermosetting prepregs.

[0170] In some implementations, see Figure 2 A single-sided copper clad laminate 20 includes an electrolytic copper foil 10 , a roughened layer 103 and an insulating substrate 201 .

[0171] The fourth aspect of the present application provides a negative electrode current collector, comprising the electrolytic copper foil of the first aspect, or the electrolytic copper foil prepared by the preparation method of the second aspect.

[0172] Electrolytic copper foil is used as the negative electrode current collector of lithium-ion batteries. The large current during the charging and discharging process will cause the negative electrode temperature to rise, and the volume of the negative electrode material will also expand when lithium ions are extracted and inserted. The electrolytic copper foil of this application is used as the negative electrode current collector. It can maintain good strength and toughness during use and will not break.

[0173] In some implementations, see Figure 3 , a lithium ion battery negative electrode 30, including an electrolytic copper foil 10 as a negative electrode current collector and a silicon-carbon negative electrode slurry layer 301 on both sides.

[0174] The fifth aspect of the present application provides a battery comprising the negative electrode current collector described in the fourth aspect.

[0175] Furthermore, batteries include but are not limited to lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, and lithium metal batteries.

[0176] In order to make the purpose, technical solutions and advantages of this application more concise and clear, this application is illustrated with the following specific examples, but this application is by no means limited to these examples. The embodiments described below are only preferred embodiments of this application and can be used to describe this application. They should not be understood as limiting the scope of this application. It should be pointed out that any modifications, equivalent replacements and improvements made within the spirit and principles of this application should be included in the scope of protection of this application.

[0177] In order to better illustrate the present application, the present application is further described below in conjunction with the embodiments. The following are specific embodiments.

[0178] In the following embodiments, the electroplating process of the electrolytic copper foil is completed in a V-shaped electroplating tank. The V-shaped electroplating tank is filled with plating solution. After each layer of electroplating is completed, water washing is performed to prevent contamination between plating solutions. The number of electroplating tanks is flexibly adjustable and is at least 3.

[0179] In the following examples, the copper ions in each electroplating solution were introduced by copper sulfate pentahydrate, and the chloride ions were introduced by hydrochloric acid.

[0180] Example 1

[0181] Step (a), electroplating the bulk crystal layer on one side of the block using a first electroplating solution:

[0182] The first electroplating solution includes the following ingredients: 45 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 70 g / L copper ions, 15 mg / L chloride ions and water.

[0183] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , the temperature of the first electroplating solution is 40°C, and the pH value of the first electroplating solution is 2.

[0184] Step (b), using a second electroplating solution to electroplate a columnar crystal layer on one side of the block crystal layer:

[0185] The second electroplating solution includes the following components: 5 mg / L sodium polydisulfide dipropane sulfonate, 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 15 mg / L chloride ion, 90 g / L copper ion concentration, 150 g / L sulfuric acid and water.

[0186] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the temperature of the second electroplating solution is 30°C.

[0187] Step (c), using a third electroplating solution to electroplate the bulk crystal layer on the other side of the columnar crystal layer away from the plated bulk crystal layer:

[0188] The third electroplating solution includes the following ingredients: 60 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 80 g / L copper ions, and 20 mg / L chloride ions.

[0189] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0190] Example 2

[0191] Step (a), electroplating the bulk crystal layer on one side of the block using a first electroplating solution:

[0192] The first electroplating solution includes the following ingredients: 20 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 70 g / L copper ions, 15 mg / L chloride ions and water.

[0193] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0194] Step (b), using a second electroplating solution to electroplate a columnar crystal layer on one side of the block crystal layer:

[0195] The second electroplating solution includes the following components: 5 mg / L sodium polydisulfide dipropane sulfonate, 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 15 mg / L chloride ion, 90 g / L copper ion concentration, 150 g / L sulfuric acid and water.

[0196] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 35℃.

[0197] Step (c), using a third electroplating solution to electroplate the bulk crystal layer on the other side of the columnar crystal layer away from the plated bulk crystal layer:

[0198] The third electroplating solution includes the following ingredients: 5 mg / L of ceric sulfate, 1.5 g / L of polypropylene glycol, 5 mg / L of sodium 4-sulfonated thia[4]arene, 20 mg / L of chloride ions, 80 g / L of copper ions and water.

[0199] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 50℃, plating solution pH value 2.

[0200] Example 3

[0201] Step (a), electroplating the bulk crystal layer on one side of the block using a first electroplating solution:

[0202] The first electroplating solution includes the following ingredients: 45 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 8 mg / L 4-sulfonated thia[4]arene sodium salt, 75 g / L copper ions, 15 mg / L chloride ions and water.

[0203] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature is 40℃, and plating solution pH value is 2.4.

[0204] Step (b), using a second electroplating solution to electroplate a columnar crystal layer on one side of the block crystal layer:

[0205] The second electroplating solution includes the following ingredients: 20 mg / L of butynediol, 8 mg / L of sodium polydisulfide propane sulfonate, 1.5 g / L of polyethylene glycol, 15 mg / L of collagen, 10 mg / L of hydroxyethyl cellulose, 15 mg / L of chloride ions, 90 g / L of copper ion concentration, 150 g / L of sulfuric acid and water.

[0206] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0207] Step (c), using a third electroplating solution to electroplate the bulk crystal layer on the other side of the columnar crystal layer away from the plated bulk crystal layer:

[0208] The third electroplating solution includes the following ingredients: 50 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 8 mg / L 4-sulfonated thia[4]arene sodium salt, 20 mg / L chloride ions, 80 g / L copper ions and water.

[0209] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature is 40℃, and plating solution pH value is 2.4.

[0210] Example 4

[0211] Step (a), electroplating the bulk crystal layer on one side of the block using a first electroplating solution:

[0212] The first electroplating solution includes the following components: 6 mg / L of cerium sulfate, 1.5 g / L of polypropylene glycol, 2 mg / L of sodium 4-sulfonated thia[4]arene, 70 g / L of copper ions, 15 mg / L of chloride ions and water.

[0213] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0214] Step (b), using a second electroplating solution to electroplate a columnar crystal layer on one side of the block crystal layer:

[0215] The second electroplating solution includes the following ingredients: 20 mg / L of butynediol, 8 mg / L of sodium polydisulfide dipropane sulfonate, 1.5 g / L of polyethylene glycol, 15 mg / L of collagen, 10 mg / L of hydroxyethyl cellulose, 20 mg / L of chloride ions, 90 g / L of copper ion concentration, 150 g / L of sulfuric acid and water.

[0216] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0217] Step (c), using a third electroplating solution to electroplate the bulk crystal layer on the other side of the columnar crystal layer away from the plated bulk crystal layer:

[0218] The third electroplating solution includes the following ingredients: 50 mg / L hexadecyltrimethylammonium chloride, 1 g / L polypropylene glycol, 3 mg / L 4-sulfonated thia[4]arene sodium salt, 20 mg / L chloride ions, 80 g / L copper ions and water.

[0219] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 50℃, plating solution pH value 2.

[0220] Example 5

[0221] Example 5 is basically the same as Example 1, except that the mass concentration of 4-sulfonated thia[4]arene sodium salt in the first and third electroplating solutions is 10 mg / L.

[0222] Example 6

[0223] Example 6 is substantially the same as Example 1, except that the mass concentration of sodium polydisulfide propane sulfonate in the second electroplating solution is 15 mg / L.

[0224] Comparative Example 1

[0225] Step (a)

[0226] The first electroplating solution includes the following components: 45 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 15 mg / L chloride ions, and 70 g / L copper ions.

[0227] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0228] Step (b)

[0229] The second electroplating solution includes the following components: 7 mg / L sodium polydisulfide dipropane sulfonate, 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 15 mg / L chloride ion, 90 g / L copper ion concentration, and 150 g / L sulfuric acid.

[0230] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0231] Step (c)

[0232] The third electroplating solution includes the following components: 6 mg / L of ceric sulfate, 2 g / L of polypropylene glycol, 20 mg / L of chloride ions, and 80 g / L of copper ions.

[0233] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0234] Comparative Example 2

[0235] Step (a)

[0236] The first electroplating solution includes the following ingredients: 45 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 15 mg / L chloride ions, and 70 g / L copper ions.

[0237] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0238] Step (b)

[0239] The second electroplating solution includes the following components: 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 15 mg / L chloride ions, 90 g / L copper ion concentration, and 150 g / L sulfuric acid.

[0240] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0241] Step (c)

[0242] The third electroplating solution includes the following ingredients: 50 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 20 mg / L chloride ions, and 80 g / L copper ions.

[0243] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0244] Comparative Example 3

[0245] Step (a)

[0246] The first electroplating solution includes the following ingredients: 40 mg / L hexadecyltrimethylammonium chloride, 1.5 g / L polypropylene glycol, 5 mg / L 4-sulfonated thia[4]arene sodium salt, 15 mg / L chloride ions, and 70 g / L copper ions.

[0247] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature is 40℃, and plating solution pH value is 1.6.

[0248] Step (b)

[0249] The second electroplating solution includes the following components: 7 mg / L sodium polydisulfide dipropane sulfonate, 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 10 mg / L chloride ion, 90 g / L copper ion concentration, and 150 g / L sulfuric acid.

[0250] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0251] Step (c)

[0252] The third electroplating solution includes the following components: 40 mg / L of hexadecyltrimethylammonium chloride, 2 g / L of polypropylene glycol, 20 mg / L of chloride ions, and 80 g / L of copper ions.

[0253] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 2A / dm 2 , plating solution temperature 40℃, plating solution pH value 2.

[0254] Comparative Example 4

[0255] Electroplating was performed directly using the second electroplating solution, which included the following components: 7 mg / L sodium polydisulfide dipropane sulfonate, 1.5 g / L polyethylene glycol, 15 mg / L collagen, 10 mg / L hydroxyethyl cellulose, 15 mg / L chloride ions, 90 g / L copper ion concentration, and 150 g / L sulfuric acid.

[0256] Electroplating conditions: anode is insoluble DSA titanium material, cathode is titanium plate, current density is 7A / dm 2 , the plating solution temperature is 30℃.

[0257] The electrolytic copper foils prepared in each embodiment and each comparative example were subjected to performance tests, and the test results are shown in Tables 1 and 2 below.

[0258] Among them, the test conditions or test standards for each performance test item are as follows:

[0259] 1) Thickness of electrolytic copper foil: obtained by converting the weight and density of electrolytic copper foil.

[0260] 2) Thickness of columnar crystal layers: Kikuchi patterns are collected from the cross-section of the copper foil using electron backscatter diffraction (EBSD). The patterns are then calculated using Oxford Instruments AZtecCrystal analysis software, which presents the differences in grain orientation between layers in the form of images, thereby determining the thickness of each layer.

[0261] 3) Grain boundary test: The grain boundary ratio is the ratio of the area covered by the grain boundaries to the total area of ​​the analysis region. The grain boundary ratio is obtained by performing orientation difference analysis on the grains based on the EBSD (electron backscatter diffraction) test results using Oxford Instruments AZtecCrystal analysis software.

[0262] 4) Grain size: The grain size is the equivalent circular diameter of the grain. Electron backscatter diffraction (EBSD) analysis was performed on the copper foil cross section at 1500x magnification using a Zeiss Sigma300 scanning electron microscope equipped with an Oxford Instruments Symmetry S3 detector. The accompanying Oxford Instruments AZtecCrystal analysis software automatically generates the test results.

[0263] 5) Internal stress difference: measured by substrate bending method, refer to GB / T 44335-2024.

[0264] 6) For tensile strength and elongation tests, refer to GB / T 5230-2020, Section 5.3.

[0265] 7) For the bending endurance test, refer to IPC-TM-650, Section 2.4.2.

[0266] 8) The definition of warpage refers to Section 6.2.5 and Appendix C of GB / T 5230-2020.

[0267] Table 1

[0268]

[0269] Table 2

[0270]

[0271] As can be seen from Tables 1 and 2 above, when Example 2 is compared with Example 1, the thickness of the copper foil columnar crystal layer of Example 2 is increased, and the tensile strength is increased from 465 MPa to 493 MPa, while the grain size of the block crystal is reduced, the elongation is reduced from 15% of Example 1 to 11.5%, and the number of bending resistance is reduced to 831.

[0272] Comparing Example 3 with Example 1, the proportion of small-angle grain boundaries in the columnar crystal layer of Example 3 increased to 71%, the corresponding grain size of the columnar crystals decreased, and the tensile strength increased from 465 MPa in Example 1 to 490 MPa.

[0273] Comparing Example 4 with Example 3, the thickness of the columnar crystal layer of Example 4 increases, and the tensile strength increases from 490 MPa to 512 MPa, while the grain size of the blocky crystal decreases, the proportion of large-angle grain boundaries in the blocky crystal layer decreases to 67%, the elongation decreases from 13% in Example 3 to 10.5%, and the bending resistance decreases slightly.

[0274] Comparing Comparative Example 1 with Example 1, the grain size of the copper foil block crystals and the proportion of large-angle grain boundaries in Comparative Example 1 are much smaller than those in Example 1, resulting in its elongation as low as 5.6% and its bending resistance times being much smaller than that in Example 1.

[0275] Comparing Comparative Example 2 with Example 2, the grain size of the copper foil columnar crystals in Comparative Example 2 increased from 196 nm in Example 2 to 300 nm, resulting in a decrease in the proportion of small-angle grain boundaries in the columnar crystal layer to 33%, and a tensile strength as low as 324 MPa.

[0276] Comparing Comparative Example 3 with Example 3, the internal stress difference between the two sides of the copper foil reached 52 MPa, the copper foil was severely warped, and the bending resistance was as low as 537 times.

[0277] Comparative Example 4 adopts the conventional electrolytic copper foil process, and the internal stress difference between the two sides is large and the warping is serious.

[0278] Comparing Examples 5 and 6 with Example 1, it can be seen that when the mass concentration of 4-sulfonated thia[4]arene sodium salt in the first electroplating solution is 2 mg / L to 8 mg / L, or when the mass concentration of polydisulfide propane sulfonate sodium salt in the second electroplating solution is 5 mg / L to 8 mg / L, the obtained electrolytic copper foil has better performance. Comparing the Examples with the Comparative Examples, it can be seen that the lack of calixarene derivatives in the first electroplating solution, the lack of organic sulfur-containing sulfonates in the second electroplating solution, or the lack of organic sulfur-containing sulfonates in the third electroplating solution cannot achieve the technical effects of the present application.

[0279] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0280] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An electrolytic copper foil, characterized in that The electrolytic copper foil has a layered structure, including a columnar crystal layer and a block crystal layer located on both sides of the columnar crystal layer. The grain size of the columnar crystal layer is 60 nm to 250 nm, and the grain size of the block crystal layer is 350 nm to 750 nm.

2. The electrolytic copper foil according to claim 1, wherein The columnar crystal layer satisfies at least one of the following conditions: (1) In the columnar crystal layer, the proportion of low-angle grain boundaries less than or equal to 10° is greater than 60%; (2) The grain size of the columnar crystal layer is 100 nm to 200 nm; (3) The ratio of the major axis to the minor axis of the grains in the columnar crystal layer is greater than or equal to 3 and less than or equal to 7.

3. The electrolytic copper foil according to claim 1, wherein The crystal texture of the columnar crystal layer includes a (111) crystal plane, a (200) crystal plane, and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane is 30% to 70%; and / or, The ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 20% to 50%; and / or, The ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 5% to 20%; and / or, The variation of the spacing between the (111) crystal plane, the (200) crystal plane and the (220) crystal plane relative to the standard sample is 1×10 -3 ~5×10 -3 .

4. The electrolytic copper foil according to any one of claims 1 to 3, characterized in that The bulk crystal layer satisfies at least one of the following conditions: (1) In the blocky crystal layer, the proportion of high-angle grain boundaries greater than or equal to 15° is greater than or equal to 65%; (2) The grain size of the bulk crystal layer is 500 nm to 700 nm; (3) The ratio of the major axis to the minor axis of the grains in the blocky crystal layer is less than or equal to 1.

4.

5. The electrolytic copper foil according to any one of claims 1 to 3, characterized in that The crystal texture of the block crystal layer includes a (111) crystal plane, a (200) crystal plane and a (220) crystal plane, and the ratio of the texture coefficient of the (111) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 20%-40%; and / or, The ratio of the texture coefficient of the (200) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 20% to 45%; and / or, The ratio of the texture coefficient of the (220) crystal plane to the sum of the texture coefficients of the (111) crystal plane, the (200) crystal plane and the (220) crystal plane is 10% to 30%; and / or, In the block crystal layer, the variation of the interplanar spacings of the (111) crystal plane, the (200) crystal plane, and the (220) crystal plane relative to the standard sample is 2×10 -4 ~7×10 -4 .

6. The electrolytic copper foil according to any one of claims 1 to 3, characterized in that At least one of the following conditions is met: (1) The thickness of the electrolytic copper foil is 9 μm to 35 μm, and the thickness of the columnar crystal layer is 5 μm to 25 μm; (2) The Poisson's ratio of the electrolytic copper foil is 0.35-0.37; (3) The internal stress difference between the two sides of the electrolytic copper foil is less than or equal to 25 MPa; (4) The average line height Rc of the contour unit of the matte surface of the electrolytic copper foil is less than or equal to 3 μm; (5) The tensile strength of the electrolytic copper foil after annealing at 180°C for 1 hour is greater than or equal to 450 MPa; (6) The elongation of the electrolytic copper foil after annealing at 180°C for 1 hour is greater than or equal to 10%; (7) The warpage of the electrolytic copper foil after annealing at 180°C for 1 hour is less than or equal to 4 mm; (8) The electrolytic copper foil has a bending resistance of greater than or equal to 800 times after annealing at 180°C for 1 hour.

7. The method for preparing an electrolytic copper foil according to any one of claims 1 to 6, wherein: The following steps are involved: forming a bulk crystal layer by electroplating using a first electroplating solution, wherein the additive of the first electroplating solution includes a calixarene derivative; Using a second electroplating solution to electroplating on one side of the block crystal layer to form a columnar crystal layer, the second electroplating solution having an additive including an organic sulfur-containing sulfonate; A third electroplating solution is used to electroplating on one side of the columnar crystal layer away from the block crystal layer to form a block crystal layer on the other side; the third electroplating solution includes a calixarene derivative.

8. The method for preparing an electrolytic copper foil according to claim 7, wherein: The calixarene derivative comprises at least one of 4-sulfonated thia[4]arene sodium salt, 4-sulfonated thia[4]arene potassium salt, 4-hydroxythia[4]arene sodium salt, calix[4]arene sulfonic acid sodium salt, and p-sulfonated thia[4]arene sodium salt; and / or, The organic sulfur-containing sulfonate includes at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, and sodium thiazoline disulfide propane sulfonate.

9. The method for preparing an electrolytic copper foil according to claim 8, wherein: The mass concentration of the sodium salt of 4-sulfonated thia[4]arene in the first electroplating solution is 1 mg / L to 10 mg / L; and / or, The mass concentration of the sodium polydisulfide propane sulfonate in the second electroplating solution is 3 mg / L to 15 mg / L; and / or, The mass concentration of the sodium salt of 4-sulfonated thia[4]arene in the third electroplating solution is 1 mg / L to 10 mg / L.

10. The method for preparing an electrolytic copper foil according to any one of claims 7 to 9, wherein: The additives of the first electroplating solution further include at least two of cerium sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol; and / or, The additives of the second electroplating solution further include at least two of butynediol, polyethylene glycol, collagen and hydroxyethyl cellulose; and / or, The additives of the third electroplating solution further include at least two of cerium sulfate, hexadecyltrimethylammonium chloride, and polypropylene glycol.

11. The method for preparing an electrolytic copper foil according to claim 10, wherein: The mass concentration of the ceric sulfate in the first electroplating solution and the third electroplating solution is 5 mg / L to 10 mg / L; and / or, The mass concentration of the hexadecyltrimethylammonium chloride in the first electroplating solution and the third electroplating solution is 10 mg / L to 100 mg / L; and / or, The mass concentration of the polypropylene glycol in the first electroplating solution and the third electroplating solution is 0.5 g / L to 5 g / L; and / or, The mass concentration of the butynediol in the second electroplating solution is 10 mg / L to 50 mg / L; and / or, The mass concentration of the polyethylene glycol in the second electroplating solution is 0.5 g / L to 5 g / L; and / or, The mass concentration of the collagen in the second electroplating solution is 10 mg / L to 50 mg / L; and / or, The mass concentration of the hydroxyethyl cellulose in the second electroplating solution is 5 mg / L to 50 mg / L.

12. A printed circuit board, characterized in that: The electrolytic copper foil comprises the electrolytic copper foil according to any one of claims 1 to 6, or the electrolytic copper foil prepared by the preparation method according to any one of claims 7 to 11.

13. A negative electrode current collector, characterized in that: The electrolytic copper foil comprises the electrolytic copper foil according to any one of claims 1 to 6, or the electrolytic copper foil prepared by the preparation method according to any one of claims 7 to 11.

14. A battery, characterized in that: Comprising the negative electrode current collector according to claim 13.

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