Novel electrolytic copper foil and preparation method therefor, and negative electrode sheet and secondary battery

Abstract

The present application relates to a novel electrolytic copper foil and a preparation method therefor, and a negative electrode sheet and a secondary battery. The novel electrolytic copper foil comprises at least one copper layer, wherein a through hole array is provided on at least part of the surface of the copper layer; the through hole array is formed by arranging M*N through holes in M rows and N columns; each row of through holes in the through hole array is arranged in an x direction; each column of through holes in the through hole array is arranged in a y direction; the x direction and the y direction intersect and are located on the same plane; the surface area of the copper layer covered by the through hole array is an array area; the surface area of the copper layer not covered by the through hole array is a non-array area; and the weight per square meter of the array area satisfies a certain relational expression. The electrolytic copper foil can effectively solve the problem of lithium ion conduction of traditional copper foils in solid-state batteries, and, when used as a negative electrode current collector of a battery, can effectively improve the performance of batteries, especially solid-state batteries.

Description

Novel electrolytic copper foil and preparation method thereof, negative electrode sheet and secondary battery TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a novel electrolytic copper foil and a preparation method thereof, a negative electrode sheet and a secondary battery. BACKGROUND

[0002] In recent years, the sales of domestic new energy vehicles have been gradually increasing every year, and power batteries are an indispensable core accessory of new energy vehicles. At present, the power batteries used are basically liquid lithium ion batteries, but the energy density of liquid lithium ion batteries has reached the upper limit, and it is difficult to have a major breakthrough. Solid-state batteries are the next generation of solutions to replace liquid lithium ion batteries. The difference between solid-state batteries and liquid lithium ion batteries is that solid-state batteries use solid-state electrolytes instead of liquid electrolytes. Further subdivision, according to the content of electrolyte, solid-state batteries can be divided into semi-solid-state batteries and full-solid-state batteries. Semi-solid-state batteries contain part of the electrolyte, and the electrolyte content is generally between 5%-10%. Full-solid-state batteries refer to electrolytes that are all solid and do not contain liquid electrolytes. Semi-solid-state batteries are an intermediate transition state of liquid batteries to full-solid-state batteries, and generally take "10% of the liquid content in the battery" as the dividing line between semi-solid-state batteries and liquid batteries. At present, semi-solid-state batteries are gradually commercialized. The conversion from liquid batteries to solid-state batteries is a long-term trend in battery technology development. The factors driving the conversion of liquid batteries to solid-state batteries are two: solid-state batteries have higher safety and energy density. Safety is a short-term driving factor, and energy density is a medium- and long-term driving factor.

[0003] Electrolytic copper foil as a lithium battery negative material current collector is an important component of the electrode structure in lithium ion batteries. It not only serves as a carrier for the negative active material of the electrode, but also plays a role in collecting and transmitting current, which has a great influence on the internal resistance and cycle performance of lithium ion batteries. In solid-state batteries, since the electrolyte is solid, the conduction process of lithium ions is more complex, and conventional double-sided bright copper foil cannot meet the special requirements of solid-state batteries. Therefore, a special copper foil needs to be designed to match the solid-state battery.

[0004] SUMMARY

[0005] The present application provides a novel electrolytic copper foil and a preparation method thereof, a negative electrode sheet and a secondary battery, which aims to improve the lithium ion conduction problem of traditional electrolytic copper foil and improve the performance of secondary batteries.

[0006] To achieve the above object, the first aspect of the present application provides a novel electrolytic copper foil, comprising at least one copper layer, wherein at least part of the surface of the copper layer is provided with a through-hole array, the through-hole array is formed by M*N through-holes arranged in M rows and N columns, M≥1, N≥1, M and N are positive integers, each row of through-holes in the through-hole array is arranged along the x direction, each column of through-holes in the through-hole array is arranged along the y direction, the x direction intersects the y direction and is in the same plane, the thickness direction of the copper layer is the z direction, and the z direction is perpendicular to the x direction and the y direction.

[0007] The thickness of the copper layer is denoted as h, the longest distance from the center point of the through-hole to the edge of the through-hole is the length of the major axis, denoted as a, the shortest distance from the center point of the through-hole to the edge of the through-hole is the length of the minor axis, denoted as b, the shortest vertical distance between adjacent through-holes along the x direction is denoted as A, the shortest vertical distance between adjacent through-holes along the Y direction is denoted as B, the Y direction is perpendicular to the x direction, the surface area of the copper layer covered by the through-hole array is the array area, the surface area of the copper layer not covered by the through-hole array is the non-array area, and the weight per square meter of the array area is denoted as m, then:

[0008] Wherein, k is any numerical value between 0.9 and 1.1.

[0009] Therefore, the electrolytic copper foil provided by the present application can improve the anti-peeling strength of the active material on the copper foil, improve its adhesion during charging and discharging, and also improve the wettability of the electrolyte, thereby improving the transmission efficiency of lithium ions, effectively solving the problem of lithium ion conduction in traditional copper foil in solid-state batteries, and effectively improving the performance of the battery, especially the solid-state battery, as the negative electrode current collector of the battery.

[0010] In any embodiment of the present application, A is 200-2000 μm, optionally 400-1500 μm, and / or B is 200-2000 μm, optionally 400-1500 μm.

[0011] In any embodiment of the present application, a is 100-1500 μm, optionally 200-1000 μm, and / or b is 100-1500 μm, optionally 200-1000 μm.

[0012] In any embodiment of the present application, the porosity of the array area is 5%-50%, optionally 10%-40%.

[0013] In any embodiment of the present application, the through-hole array is arranged in a rectangular array and / or a rhombic array.

[0014] In any embodiment of the present application, the through-hole is circular and / or elliptical.

[0015] In any embodiment of the present application, the copper layer has two surfaces opposite in the thickness direction of the copper layer, namely a first surface and a second surface, and the first surface and the second surface have different surface roughness and / or brightness.

[0016] In any embodiment of the present application, the thickness of the copper layer is 3 μm-15 μm.

[0017] In any embodiment of the present application, the tensile strength of the electrolytic copper foil at room temperature is 15 kgf / mm 2 -30 kgf / mm 2 , the tensile strength of the non-array region of the copper layer at room temperature is 30 kgf / mm 2 -70 kgf / mm 2 , and the room temperature is 25±5℃.

[0018] The second aspect of the present application provides a method for preparing an electrolytic copper foil, comprising the following steps:

[0019] placing an anode and a cathode to be plated in an electrolyte to perform electrolysis to obtain an electrolytic copper foil, wherein the cathode has electrically insulating shielding points arranged in an array.

[0020] In any embodiment of the present application, the electrolyte comprises copper ions, sulfuric acid, halide ions and an organic additive;

[0021] Optionally, the concentration of the copper ions in the electrolyte is 70 g / L-130 g / L;

[0022] Optionally, the concentration of the sulfuric acid in the electrolyte is 80 g / L-150 g / L;

[0023] Optionally, the concentration of the chloride ions in the electrolyte is 15 mg / L-50 mg / L;

[0024] Optionally, the concentration of the organic additive in the electrolyte is 20 mg / L-500 mg / L.

[0025] In any embodiment of the present application, the organic additive comprises a leveling agent, a brightener and a wetting agent,

[0026] the leveling agent is a nitrogen-containing compound, and optionally comprises one or more of collagen, gelatin, thiourea, allyl thiourea, ethylene thiourea and 2-amino-4-methylbenzothiazole, and optionally the mass concentration of the leveling agent in the electrolyte is 0.1 mg / L-40 mg / L; and / or,

[0027] The brightener is an organic divalent sulfide, optionally including one or more of sodium polydithio-dipropyl sulfone, sodium N,N-dimethyl-dithioformamide propyl sulfone, sodium 3-mercaptopropane sulfonate, sodium 3-(benzothiazole-2-mercapto) propane sulfonate, and isothiuronium propyl sulfone inner salt, optionally the mass concentration of the brightener in the electrolyte is 0.1 mg / L-400 mg / L; and / or,

[0028] The wetting agent is a polyether compound, optionally including one or more of polyethylene glycol, hydroxyethyl cellulose, polypropylene glycol, allyl polyethylene glycol, and fatty amine polyoxyethylene ether, optionally the mass concentration of the wetting agent in the electrolyte is 1 mg / L-40 mg / L.

[0029] In any embodiment of the present application, the temperature of the electrolyte in the electrolysis process is 45℃-60℃.

[0030] The third aspect of the present application provides a negative electrode tab, including the electrolytic copper foil or the electrolytic copper foil prepared by the method.

[0031] The fourth aspect of the present application provides a secondary battery, including the negative electrode tab.

[0032] In any embodiment of the present application, the secondary battery is a liquid, semi-solid or solid battery.

[0033] The fifth aspect of the present application provides a power device, including at least one of the secondary batteries.

[0034] The power device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.

[0035] The details of one or more embodiments of the present application are presented in the accompanying drawings and description below. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to better describe and illustrate the embodiments or examples provided by the present application, one or more drawings can be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the presently described embodiments or examples, and any one of the best modes of these applications presently understood. Moreover, the same reference numbers are used to represent the same components throughout the drawings. In the drawings:

[0037] FIG. 1 is a schematic diagram of a rectangular array arrangement;

[0038] FIG. 2 is a schematic diagram of a diamond array arrangement;

[0039] Fig. 3 is an SEM image of an array region of the electrolytic copper foil prepared in Example 1 of the present application;

[0040] Fig. 4 is a photograph of a finished roll of the electrolytic copper foil prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0041] Hereinafter, some embodiments of the novel electrolytic copper foil and its production method, negative electrode sheet, secondary battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed explanations are omitted. For example, there will be cases where detailed explanations of matters well known, repeated explanations of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0042] The "ranges" disclosed in the present application can be defined in the form of lower and upper limits, a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, either end value can be included or excluded independently, and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are also listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" represents a shorthand manner of describing each and every numerical value that is contained within the range, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand manner of describing those numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥ 2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when it is stated that a certain parameter is an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0043] In the present application, "a plurality of", "a plurality of kinds", etc. refer to more than 2 or equal to 2 in number, unless otherwise specified. For example, "one or more" means one or more than two.

[0044] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0045] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment or implementation of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As those skilled in the art will appreciate, embodiments described herein can be combined with one another, unless specifically noted otherwise. Reference herein to "an implementation" is to be understood similarly.

[0046] Those skilled in the art will understand that, in the methods of the various implementations or embodiments, the order of execution of the steps is not necessarily the order in which the steps are written, and the detailed execution order of the steps should be determined according to their functions and possible inherent logical relationships. If not specifically stated, all steps of the application can be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the method can also include step (c), which means that step (c) can be added to the method in any order, for example, the method can include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0047] In the present application, the open technical features or technical solutions described with the words "containing", "including", "comprising" and the like, if not otherwise specified, do not exclude additional members from the listed members, and can be regarded as providing both a closed feature or solution consisting of the listed members, and an open feature or solution including additional members in addition to the listed members. For example, A includes a1, a2 and a3, if not otherwise specified, it can also include other members, or it can not include additional members, and can be regarded as providing both the feature or solution that "A consists of a1, a2 and a3", and the feature or solution that "A includes a1, a2 and a3, and also includes other members". In the present application, if not otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0048] In the present application, "optionally", "optional" and "optional" mean that it can or can not be present, i.e. it means to choose from either of the two parallel solutions "yes" or "no". If there are multiple "optional" in a technical solution, if not otherwise specified, and there is no contradictory relationship or mutual restriction, each "optional" is independent of each other.

[0049] In solid-state batteries, traditional copper foils are used as current collectors. However, the adhesion between traditional copper foils and negative active materials is poor, and the electrolyte has poor wettability on the electrode surface, leading to problems in lithium ion conduction.

[0050] Therefore, the first aspect of the present application provides a novel electrolytic copper foil, which comprises at least one copper layer. The copper layer has a through-hole array on at least part of its surface. The through-hole array is formed by M*N through-holes arranged in M rows and N columns, where M≥1, N≥1, M and N are positive integers, each row of through-holes in the through-hole array is arranged along the x direction, each column of through-holes in the through-hole array is arranged along the y direction, the x direction and the y direction intersect and are in the same plane, the thickness direction of the copper layer is the z direction, and the z direction is perpendicular to both the x direction and the y direction.

[0051] The thickness of the copper layer is denoted as h, the longest distance from the center point of the through-hole to the edge of the through-hole is the major semi-axis distance, which is denoted as a, the shortest distance from the center point of the through-hole to the edge of the through-hole is the minor semi-axis distance, which is denoted as b, the shortest vertical distance between adjacent through-holes along the x direction is denoted as A, the shortest vertical distance between adjacent through-holes along the Y direction is denoted as B, the Y direction is perpendicular to the x direction, the surface area of the copper layer covered by the through-hole array is the array area, the surface area of the copper layer not covered by the through-hole array is the non-array area, and the weight per square meter of the array area is denoted as m. Then:

[0052] where k is any number between 0.9 and 1.1.

[0053] After coating the negative electrode material, the through-holes of the above-mentioned electrolytic copper foil will be filled with negative electrode material, improving the peel strength of the negative electrode material on the copper foil. The through-hole structure of the copper foil helps to improve the wettability of the electrolyte on the electrode surface, thereby improving the transmission efficiency of lithium ions. Especially in solid-state batteries, the above-mentioned electrolytic copper foil is used as the current collector of the negative electrode, which not only can collect current but also can form a good interface in the solid-state electrolyte, thereby effectively transmitting current. Good interface characteristics can reduce energy loss during charging and discharging of the battery, improve energy density and cycle life of the battery. In addition, the above-mentioned electrolytic copper foil can also reduce the internal impedance of the battery, further improving the charging and discharging performance of the battery. Compared with traditional copper foils, the above-mentioned electrolytic copper foil has a lighter weight (weight reduction can reach 20%) under the same specifications and size, which reduces the weight proportion of the copper foil in the battery module and improves the energy density of the battery. The above-mentioned electrolytic copper foil can also reduce the battery aging time and the amount of electrolyte, improving the safety of the battery.

[0054] The through-hole array refers to the center points of the through-hole structures being arranged in an array. In some embodiments, the through-holes in the through-hole array are circular and / or elliptical. For circular through-holes, the center points are arranged in an array, and the circular holes are also arranged in an array, and the arrangement of the two is consistent. For elliptical through-holes, the center points are taken as the base points for rotation, and the arrangement of the major axis or the minor axis in different directions can be obtained. The difference in direction can cause the through-holes to not be arranged in an array. Therefore, the arrangement of the through-hole array is based on the arrangement of the center points.

[0055] In some embodiments, the through-hole array is arranged in a rectangular array. As shown in FIG. 1, the through-hole array is arranged in a rectangular array, and the x direction is perpendicular to the y direction. In this embodiment, the Y direction is the same as the y direction. The longest distance from the center point of the through-hole to the edge of the through-hole is the major semi-axis distance, and the length is a. The shortest distance from the center point of the through-hole to the edge of the through-hole is the minor semi-axis distance, and the length is b. The shortest vertical distance between adjacent through-holes along the x direction is A, and the shortest vertical distance between adjacent through-holes along the Y direction is B. The electrolytic copper foil with the through-hole array arranged in a rectangular array has a surface density that is basically close in different areas per unit area. When stretched under the action of a winding tension, the stress distribution is uniform, and the array area is not prone to deformation or wrinkling.

[0056] In some embodiments, the through-hole array is arranged in a diamond array. As shown in FIG. 2, the through-hole array is arranged in a diamond array, and the x direction intersects the y direction at a certain angle but is not perpendicular. The x direction is perpendicular to the Y direction. In this embodiment, the Y direction is not the same as the y direction. The longest distance from the center point of the through-hole to the edge of the through-hole is the major semi-axis distance, and the length is a. The shortest distance from the center point of the through-hole to the edge of the through-hole is the minor semi-axis distance, and the length is b. The shortest vertical distance between adjacent through-holes along the x direction is A, and the shortest vertical distance between adjacent through-holes along the Y direction is B.

[0057] In some embodiments, A is 200-2000 μm and any value or range of any two values therebetween, for example, A can also be 500 μm, 600 μm, 700 μm, 800 μm, 1000 μm, 1200 μm, 1400 μm, 1600 μm, 1800 μm, and further, A can be selected to be 400-1500 μm.

[0058] In some embodiments, B is 200-2000 μm and any value or range of any two values therebetween, for example, B can also be 500 μm, 600 μm, 700 μm, 800 μm, 1000 μm, 1200 μm, 1400 μm, 1600 μm, 1800 μm, and further, B can be selected to be 400-1500 μm.

[0059] In some embodiments, a is 100-1500 μm and any value or range between any two of them, for example, it can also be 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, further, a can be selected as 200-1000 μm.

[0060] In some embodiments, b is 100-1500 μm and any value or range between any two of them, for example, it can also be 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, further, b can be selected as 200-1000 μm.

[0061] It needs to be further explained that the array area includes the through holes and the copper layer area between adjacent through holes, and the non-array area is the remaining copper layer area.

[0062] In some embodiments, the porosity of the array area is 5%-50% and any value or range between any two of them, for example, it can also be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, further, it can be selected as 10-40%.

[0063] The porosity of the array area is defined as the ratio of the through hole area of the copper layer to the unit area. When the porosity of the array area is in the above range, the performance of the electrolytic copper foil as the negative current collector is better. When the porosity is greater than 50%, the through holes are densely distributed on the copper layer, and the interval between adjacent through holes is small. In the rolling process, the electrolytic copper foil is prone to folding or breaking. When the porosity is less than 5%, the adhesion of the negative active material to the electrolytic copper foil is relatively poor and easy to fall off when the electrolytic copper foil is used as the negative current collector, resulting in poor application effect of the electrolytic copper foil at the battery end.

[0064] The thickness of the copper layer has the meaning known in the art and can be measured by methods known in the art, for example, the area density of the copper layer is obtained by using the weighing method, and then the thickness of the copper layer is derived from the area density of the copper layer.

[0065] In some embodiments, the thickness of the copper layer is 3 μm-15 μm and any value or range between any two of them. Understandably, the thickness of the copper layer can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm. The thickness of the copper layer in this range can further improve the capacity of the battery.

[0066] In some embodiments, the copper layer has two surfaces opposite to each other in the thickness direction of the copper layer, which are referred to as a first surface and a second surface, respectively. The first surface and the second surface have different surface roughness and / or brightness. It is understood that the vertical distance between the first surface and the second surface is the thickness of the copper layer.

[0067] In some embodiments, the electrolytic copper foil further comprises at least one protective layer. Optionally, the protective layer comprises a first protective layer and a second protective layer, the first protective layer is disposed on the first surface, and the second protective layer is disposed on the second surface. The protective layer can effectively reduce the oxidation of the surface of the electrolytic copper foil.

[0068] In some embodiments, the protective layer comprises at least one of chromium, glucose, and nitride.

[0069] In some embodiments, the protective layer comprises chromium. Optionally, the content of chromium in the at least one protective layer is 20 ppm to 80 ppm and any value or range between any two values thereof, for example, 30 ppm, 40 ppm, 50 ppm, 60 ppm, or 70 ppm.

[0070] In some embodiments, the thickness of the first protective layer is 100 nm to 300 nm, and / or the thickness of the second protective layer is 100 nm to 300 nm. It is understood that the thickness of the first protective layer can be independently selected from 100 nm to 300 nm and any value or range between any two values thereof, for example, 150 nm, 200 nm, or 250 nm; and the thickness of the second protective layer can be independently selected from 100 nm to 300 nm and any value or range between any two values thereof, for example, 150 nm, 200 nm, or 250 nm.

[0071] In some embodiments, the tensile strength of the array region of the copper layer at room temperature is 15 kgf / mm 2 to 30 kgf / mm 2 and any value or range between any two values thereof, for example, 16 kgf / mm 2 , 18 kgf / mm 2 , 20 kgf / mm 2 , 22 kgf / mm 2 , 25 kgf / mm 2 , or 28 kgf / mm 2 . The room temperature is 25 ± 5 °C.

[0072] The electrolytic copper foil has better mechanical strength when the tensile strength of the array region is within the range. When the tensile strength of the array region is less than 15 kgf / mm 2, the electrolytic copper foil is easy to break under the action of tension, and the electrolytic copper foil is also easy to break under the action of extrusion when manufacturing the negative electrode of the battery. The tensile strength of the array region is greater than 30 kgf / mm 2 , there are a large number of through holes in the electrolytic copper foil, the stress area becomes small under the action of external force, and the edge region of the through hole is easy to break.

[0073] In some embodiments, the non-array region of the copper layer has a tensile strength at room temperature of 30 kgf / mm 2 -70 kgf / mm 2 and any value therebetween or a range between two values, for example, it can also be 35 kgf / mm 2 , 40 kgf / mm 2 , 45 kgf / mm 2 , 50 kgf / mm 2 , 55 kgf / mm 2 , 60 kgf / mm 2 , 65 kgf / mm 2 . The room temperature is 25±5℃. The electrolytic copper foil has better mechanical strength when the tensile strength of the non-array region is within the range.

[0074] The second aspect of the present application provides a preparation method of an electrolytic copper foil, comprising the following steps:

[0075] placing an anode and a cathode to be plated in an electrolyte to obtain an electrolytic copper foil, wherein the cathode has an array of electrically insulating shielding points.

[0076] The above method is a one-step forming method. The so-called one-step forming method is that the copper foil produces a porous structure in the corresponding region during the electrolysis process, without the need for post-processing. In the existing mature electrolytic copper foil process, the copper foil produced is generally non-porous, and to achieve a porous copper foil, post-processing of the non-porous copper foil is required, such as mechanical punching, chemical corrosion, electrochemical corrosion, and laser punching, etc., which cannot achieve one-step forming.

[0077] The principle of the above method is as follows. In the electrolytic copper foil system, the cathode roller serves as the cathode, and electrons flow or migrate on the surface of the cathode roller. Copper ions in the electrolyte migrate to the surface of the cathode roller under the action of the cathode and anode electric field and the liquid flow rate. The flowing electrons on the surface of the cathode roller are transferred to the copper ions close to the cathode roller. The copper ions obtain an electron to form cuprous ions. The cuprous ions continue to obtain an electron from the surface of the cathode roller to form copper atoms. Finally, the copper atoms are fixed on the surface of the cathode roller and gradually accumulate to form a copper foil of a certain thickness. Therefore, the area of the cathode roller immersed in the electrolyte is completely covered with the electrolytic copper foil. The electrically insulating shielding point is made of a high-molecular material with high volume resistivity, which has excellent electrical insulation performance and can isolate the charged part from the uncharged part, so that the electric current acts in the specified area. The electrically insulating shielding point is prepared on the surface of the cathode roller. Although electrons pass through the shielded area of the cathode roller during the electrolysis process, the electrons cannot be received by the copper ions in the electrolyte because the surface is covered with the electrically insulating shielding point. The electrons can only migrate or flow to the area without electrically insulating shielding to react with the copper ions to form a copper foil. The area shielded by the electrically insulating shielding cannot generate a copper foil by electrolysis, and finally forms a through hole in the copper foil.

[0078] In some embodiments, the electrically insulating shielding point is made of an organic high-molecular material with a volume resistivity greater than 10 9 Ω·cm. Without particular limitation, the electrically insulating shielding material used includes, but is not limited to, ultraviolet light curing materials, heat curing materials, and moisture curing materials. These materials exist in a liquid state in the initial state, and after ultraviolet light curing or heat curing or moisture curing, the material form changes from liquid to solid. The ultraviolet light curing material has acrylate groups and / or epoxy groups. Under the irradiation of ultraviolet light with a certain energy density, the acrylate groups or epoxy groups react to form a three-dimensional network of high-molecular materials. The heat curing material is a three-dimensional network of high-molecular materials formed by active groups under the action of initiators or crosslinking agents at high temperatures. Moisture curing is a condensation polymerization reaction of active functional groups in the material to capture water molecules in the air to form a three-dimensional network of high-molecular materials.

[0079] The distribution of the electrically insulating shielding point on the cathode roller is the same as the distribution of the through hole array on the electrolytic copper foil.

[0080] The method for preparing the electrically insulating shielding points can adopt a template method or a direct forming method. The template method adopts an adhesive tape to prepare, the adhesive tape is punched in a manner of a required through-hole array, then the adhesive tape is adhered to the surface of the cathode roller, the shielding material is fully coated in the through-hole of the adhesive tape, the adhesive tape is torn off after the coating of the shielding material is completed, the shielding material in the through-hole of the adhesive tape remains on the surface of the cathode roller, and finally the shielding material is solidified to complete the preparation of the shielding points. The direct forming method is to use an automatic equipment to directly prepare the shielding points on the surface of the cathode roller through an automatic program setting and an automatic dispensing manner, and the shielding points can be solidified in the process of the automatic dispensing.

[0081] In some embodiments, the concentration of copper ions in the electrolyte is 70 g / L-130 g / L and any value or range between any two values thereof, for example, it can also be 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 110 g / L, 120 g / L. When the concentration of copper ions is in this range, electrolysis can be carried out at high current density, improving the efficiency of electrolysis. When the concentration of copper ions is high, copper sulfate is easy to precipitate, and when the concentration of copper ions is low, the conductivity of the electrolyte is low, and the current density is also reduced, resulting in low electrolysis efficiency.

[0082] In the process of configuring the electrolyte, the source of copper ions can be metallic copper, such as copper wire, copper plate, etc., which can be further dissolved in a sulfuric acid solution to form a sulfuric acid-copper sulfate solution.

[0083] In some embodiments, the concentration of sulfuric acid in the electrolyte is 80 g / L-150 g / L and any value or range between any two values thereof, for example, it can also be 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L. When the concentration of sulfuric acid is high, the corrosion ability to the equipment increases, which reduces the service life of the equipment, and at the same time, the solubility of copper sulfate in the electrolyte decreases, which is easy to crystallize at the edge of the electrolytic cell, and even the pipeline is blocked by crystallization. When the concentration of sulfuric acid is low, the electrolysis efficiency is affected. When the concentration of sulfuric acid is in this suitable range, it is more conducive to electroplating.

[0084] In some embodiments, the mass concentration of halide ions (including chloride ions, bromide ions, iodide ions, etc.) in the electrolyte is 15 mg / L-50 mg / L and any value or range between any two values thereof, for example, it can also be 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L. Under the low pH condition of acid copper plating, chloride ions will be adsorbed on the cathode copper with high coverage, and the preferential adsorption surface is the (111) surface. During the thickening process of the copper layer, chloride ions can continuously move to the surface position, and the adsorbed Cl -It does not hinder the deposition of copper, and even can attract copper ions and act as a channel for electron transfer. During electrodeposition, chloride ions can be adsorbed on specific surfaces of crystal growth, affect the crystal growth behavior and crystal properties, change the surface morphology, and help to refine the grains. In addition, under the action of cathode reduction, chloride ions are easy to form CuCl with Cu + complexes, and CuCl acts differently at different potentials. Generally, when the potential is more positive, although Cl - can coordinate with Cu + to promote the conversion of Cu 2+ / Cu + , but the insoluble passivation film of CuCl formed will be adsorbed on the cathode surface, inhibiting the conversion of Cu + / Cu, thereby showing a strong inhibitory effect on the electrodeposition of copper. When the potential is more negative, the passivation film dissolves rapidly, Cu + -Cl - complexes, and the chlorine bridge of the complex is strengthened, catalyzing the further electrode reduction and deposition of Cu + / Cu, at which time the chloride ions act as a promoter for electrodeposition.

[0085] During the preparation of the electrolyte, the source of halide ions can be HX, NaX or KX, where X is a halide ion.

[0086] In some embodiments, the concentration of the organic additive in the electrolyte is 20 mg / L-500 mg / L and any value or range between any two values therebetween, for example, it can also be 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 110 mg / L, 120 mg / L, 130 mg / L, 140 mg / L. When chloride ions are used alone as an additive, the performance of the copper foil prepared is less stable, and chloride ions can be combined with other organic additives to act as a chlorine bridge. For example, chloride ions can form Cu + -Cl - complexes, which can provide binding sites for ether bond adsorption in polyether compounds, and due to their negative charge, they are easy to have electrostatic interaction with positively charged nitrogen-containing compounds, and easy to form an adsorption barrier layer on the cathode surface; for another example, chloride ions can combine with organic sulfides and copper ions and form bridging, accelerate mass transfer, and improve the deposition rate of Cu 2+ . If the concentration of chloride ions is too low, the synergistic effect with organic additives is weak, which is not conducive to the improvement of the mechanical strength of the copper foil; if the concentration of chloride ions is too high, nodular copper particles will appear on the surface of the copper foil, affecting the performance of the product.

[0087] In some embodiments, the organic additive includes a leveling agent, a brightener, and a wetting agent.

[0088] In some embodiments, the leveler is a nitrogen-containing compound, optionally including one or more of collagen, gelatin, thiourea, allyl thiourea, ethylene thiourea, and 2-amino-4-methylbenzothiazole. The mass concentration of the leveler in the electrolyte includes, but is not limited to, 0.1 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L. The leveler can improve the tensile strength and elongation of the electrolytic copper foil.

[0089] In some embodiments, the brightener is an organic divalent sulfide, optionally including one or more of sodium polydithiobispropyl sulfonate (SPS), sodium N,N-dimethyl-dithioformamide propyl sulfonate (DPS), sodium 3-mercaptopropane sulfonate (MPS), sodium 3-(benzothiazole-2-mercapto) propane sulfonate (ZPS), and isothiuronium propyl sulfonate inner salt (UPS). The mass concentration of the brightener in the electrolyte includes, but is not limited to, 0.1 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L.

[0090] In some embodiments, the wetting agent is a polyether compound, optionally including one or more of polyethylene glycol, hydroxyethyl cellulose, polypropylene glycol, allyl polyethylene glycol, and fatty amine polyoxyethylene ether. The mass concentration of the wetting agent in the electrolyte includes, but is not limited to, 1 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L. The wetting agent can improve the leveling and wetting of the copper deposition layer, increase the dispersion capacity of copper ions after being added, and eliminate pinholes in the copper plating layer, making the crystal grains of the plating layer uniform, fine, and compact.

[0091] In some embodiments, the temperature of the electrolyte during the electrolysis process is 45-60°C.

[0092] In some embodiments, the flow rate of the electrolyte during the electrolysis process is 30-60 m 3 / h.

[0093] In some embodiments, the anode is a titanium plate with an iridium-tantalum coating on the surface of the titanium plate.

[0094] In some embodiments, the cathode is a cathode roller, which can be made of high-purity titanium.

[0095] In some embodiments, the above method further includes a step of placing the electrolytic copper foil in a passivation solution for passivation. Optionally, the passivation solution includes one or more of a chromium source, glucose, and a nitride.

[0096] Further, in some embodiments, the above method further includes one or more of the following steps: stripping the copper plating layer from the cathode, water washing, drying, and coiling.

[0097] In addition, the secondary battery and the electric device of the present application are described below.

[0098] Generally, the secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, and functions to prevent short circuit between the positive electrode and the negative electrode, while allowing ions to pass through.

[0099] Positive electrode sheet

[0100] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material layer is disposed on either one or both of the two surfaces of the positive electrode current collector.

[0101] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base material. In the positive electrode current collector, non-limiting examples of the metal material can include one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, a silver alloy, and the like. In the positive electrode current collector, non-limiting examples of the polymer material base material can include one or more of a polypropylene (PP) base material, a polyethylene terephthalate (PET) base material, a polybutylene terephthalate (PBT) base material, a polystyrene (PS) base material, a polyethylene (PE) base material, and the like.

[0102] In some embodiments, the positive electrode active material can be a positive electrode active material for a battery known in the art.

[0103] It is to be noted that the secondary battery of the present application can be a lithium ion battery, a sodium ion battery.

[0104] As a non-limiting example of a lithium ion battery, the positive active material can include one or more of: lithium-containing phosphates of olivine structure, lithium transition metal oxides, and modified compounds of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive active material for a battery can also be used. These positive active materials can be used alone only one kind, or two or more kinds in combination. Among them, examples of the lithium transition metal oxide can include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Non-limiting examples of lithium-containing phosphates of olivine structure can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon. Non-limiting examples of lithium cobalt oxide can include LiCoO2; non-limiting examples of lithium nickel oxide can include LiNiO2; non-limiting examples of lithium manganese oxide can include LiMnO2, LiMn2O4, and the like; non-limiting examples of lithium nickel cobalt manganese oxide can include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to simply as NCM 811 ), and the like. Non-limiting examples of lithium nickel cobalt aluminum oxide can include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0105] As a sodium ion active material can include at least one or more of: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventional well-known materials that can be used as a positive active material for a sodium ion battery can also be used.

[0106] As an optional technical solution of the present application, the transition metal in the sodium transition metal oxide can be at least one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Non-limiting examples of the sodium transition metal oxide can be NaxMO2, where M can include one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0107] As a non-limiting example of the sodium ion battery, the positive electrode active material can include one or more of the following materials: one or more of sodium transition metal oxides, polyanion compounds and prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium ion batteries can also be used.

[0108] In some embodiments, the positive electrode active material layer can also optionally include a binder. As a non-limiting example, the binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.

[0109] In some embodiments, the positive electrode active material layer can also optionally include a conductive agent. As a non-limiting example, the conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0110] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one side surface of the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode tab can be obtained. The type of the solvent can be selected from, but not limited to, any of the aforementioned embodiments, such as N-methyl pyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector, or on both surfaces of the positive electrode current collector. The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector, or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 to 25000 mPa·s. When coating the positive electrode slurry, the coating unit area density based on the dry weight (excluding the solvent) can be 15 to 35 mg / cm 2 . The compaction density of the positive electrode tab can be 3.0 to 3.6 g / cm3 Optionally, 3.3-3.5 g / cm3 3

[0111] Negative electrode sheet

[0112] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector, the negative active material layer including a negative active material. For example, the negative current collector has two surfaces opposite in the thickness direction of the negative current collector, and the negative active material layer is disposed on either one or both of the two surfaces of the negative current collector.

[0113] In some embodiments, the negative active material layer can optionally include a binder. The binder can include one or more of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0114] In some embodiments, the negative active material layer can optionally include a conductive agent. The conductive agent can include one or more of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0115] In some embodiments, the negative active material layer can optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0116] In some embodiments, the negative active material layer can optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0117] ​In some embodiments, the negative electrode sheet can be prepared by dispersing the components described above for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (a non-limiting example of the solvent is deionized water), to form a negative electrode slurry; coating the negative electrode slurry on at least one side surface of the negative electrode current collector; and drying, cold-pressing, or the like, to obtain the negative electrode sheet. The surface of the negative electrode current collector to which the negative electrode slurry is coated can be a single surface of the negative electrode current collector, or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40 wt% to 60 wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa·s to 10000 mPa·s. The coating unit area density of the negative electrode slurry, on a dry weight basis (excluding the solvent), can be 75 g / m 2 to 220 g / m 2 . The compaction density of the negative electrode sheet can be 1.0 g / cm 3 to 1.8 g / cm 3 .

[0118] Electrolyte

[0119] The electrolyte has a function of conducting ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not particularly limited in the present application, and can be selected as needed. For example, the electrolyte can be liquid, gel, or solid, and the electrolytic copper foil of the present application is particularly suitable for a battery using a solid electrolyte.

[0120] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0121] In some embodiments, the electrolyte salt can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluoro-oxalato-borate (LiDFOB), lithium bis-oxalato-borate (LiBOB), lithium difluoro-bis-oxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0122] In some embodiments, the solvent can include ethylene carbonate (EC, ), propylene carbonate (PC, ), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethylene carbonate one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0123] In some embodiments, the electrolyte solution can further optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive that can improve certain performance of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high-temperature or low-temperature performance of the battery, and the like.

[0124] In some embodiments, the additive in the electrolyte solution can include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0125] Separator film

[0126] In some embodiments, the secondary battery further includes a separator film. The type of the separator film is not particularly limited in the present application, and any publicly known porous structure separator film having good chemical stability and mechanical stability can be used.

[0127] In some embodiments, the material of the separator film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different, and are not particularly limited.

[0128] In some embodiments, the thickness of the separator film is 6 μm to 40 μm, and can be optionally 12 μm to 20 μm.

[0129] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be used to make an electrode assembly through a winding process or a stacking process.

[0130] In some embodiments, the secondary battery can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0131] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and the like. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, and the like.

[0132] The secondary battery includes at least one battery cell. The secondary battery can include one or more battery cells.

[0133] In the present application, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy to each other, and further, generally includes at least a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct the active ions between the positive electrode sheet and the negative electrode sheet.

[0134] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other shape.

[0135] In some embodiments, the outer package can include a housing and a cover plate. The housing can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be wound or stacked to form an electrode assembly. The electrode assembly is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly. The number of electrode assemblies contained in the battery cell can be one or more, and the skilled person can select the appropriate number according to the actual needs.

[0136] The secondary battery can be a battery module or a battery pack.

[0137] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, and the skilled person can select the appropriate number according to the application and capacity of the battery module.

[0138] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the skilled person can select the appropriate number according to the application and capacity of the battery pack.

[0139] In addition, the present application also provides a power consuming device, which includes the secondary battery provided by the present application. The secondary battery can be used as a power source of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can include a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto. The mobile device can be a mobile phone, a notebook computer, etc., for example; the electric vehicle can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0140] As a power consuming device, the secondary battery can be selected according to the use requirements thereof.

[0141] As an example, the power consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the demand of the power consuming device for high power and high energy density of the secondary battery, a battery pack or a battery module can be used.

[0142] As another example, the device can be a mobile phone, a tablet, a notebook computer, etc. The device usually requires thinning, and a secondary battery can be used as a power source.

[0143] Embodiment

[0144] Hereinafter, an embodiment of the present application will be described. The embodiment described below is exemplary and is for the purpose of explanation of the present application only and is not to be understood as a limitation of the present application. In the embodiment, a technique or a condition not mentioned is performed in accordance with a technique or a condition described in a document in the art or in accordance with a product manual. The reagent or the apparatus used, for which the manufacturer is not mentioned, is a general product that can be obtained on the market.

[0145] Embodiment 1

[0146] 1) Preparation of cathode electrically insulating shield points

[0147] Electrically insulating shield points having a rectangular array were prepared on the surface of a rotating cathode roll using a direct molding method. The electrically insulating shield points used a circle, i.e., a = b = 160 μm, A = B = 500 μm, and an ultraviolet light-cured material was used as the electrically insulating material.

[0148] 2) Electrolysis

[0149] A copper wire having a copper content of 99.99% was dissolved in sulfuric acid to form a sulfuric acid-copper sulfate solution, and an organic additive and hydrochloric acid were added and stirred uniformly to obtain an initial electrolyte. The electrolyte was filtered using a filter having a filtration precision of less than 0.5 μm to obtain a pure electrolyte. A cathode roll was used as the cathode, and a titanium plate having an iridium tantalum coating on the surface was used as the anode. The anode and the cathode were separated by the electrolyte, and the anode-cathode distance was 8 mm.

[0150] In the electrolyte, the concentration of sulfuric acid was 115 g / L, the concentration of copper ions was 85 g / L, the concentration of chloride ions was 20 mg / L, the concentration of sodium polydithiopropanesulfonate was 12 mg / L, the concentration of isothiouronium propyl sulfonic acid inner salt was 4 mg / L, the concentration of polyethylene glycol (molecular weight 4000-6000) was 15 mg / L, the concentration of collagen was 5 mg / L, and the current density was 7000 A / m 2 A porous copper foil having a thickness of 6 μm was prepared, the electrolyte temperature was 50°C, and the electrolyte flow rate was 40 m 3 / h.

[0151] The cathode roller rotates at a constant speed, and copper in the solution is deposited onto the surface of the cathode roller to form a copper foil, the thickness of the copper foil being controlled by the cathode current density and the rotating speed of the cathode roller, and those skilled in the art can control the current density and the rotating speed of the cathode roller by using conventional methods to obtain a copper foil with a target thickness. After the copper foil is turned out of the solution with the roller, it is continuously peeled off from the cathode roller, washed with water, passivated, dried, and coiled to form an electrolytic copper foil.

[0152] The SEM image of the electrolytic copper foil prepared in this example in the array area is shown in Fig. 3, and the finished coil sample is shown in Fig. 4.

[0153] Example 2

[0154] 1) Preparation of cathode insulation shielding points

[0155] The direct forming method is used to prepare electrically insulated shielding points with a rectangular array on the surface of the rotating cathode roller, the electrically insulated shielding points use a circle, i.e. a = b = 300 μm, A = B = 800 μm, and the electrically insulated material uses an ultraviolet light curing material.

[0156] 2) Electrolysis

[0157] A copper wire with a copper content of 99.99% is dissolved in sulfuric acid to form a sulfuric acid-copper sulfate solution, and then organic additives and hydrochloric acid are added and stirred uniformly to obtain an initial electrolyte. The electrolyte is filtered using a filter with a filtering precision of less than 0.5 μm to obtain a pure electrolyte. The cathode uses a cathode roller, and the anode uses a titanium plate with an iridium tantalum coating on the surface. The anode and the cathode are separated by the electrolyte, and the anode-cathode distance is 8 mm.

[0158] In the electrolyte, the concentration of sulfuric acid is 110 g / L, the concentration of copper ions is 90 g / L, the concentration of chloride ions is 25 mg / L, the concentration of sodium polydithiopropanesulfonate is 30 mg / L, the concentration of sodium 3-(benzothiazole-2-mercapto) propane sulfonate is 15 mg / L, the concentration of polyethylene glycol (molecular weight 4000-6000) is 9 mg / L, the concentration of hydroxyethyl cellulose is 4 mg / L, the concentration of thiourea is 3 mg / L, and the current density is 6500 A / m 2 . A porous copper foil with a thickness of 6 μm is prepared, the electrolyte temperature is 53 °C, and the electrolyte flow rate is 45 m 3 / h.

[0159] The cathode roller rotates at a constant speed, and copper in the solution is deposited onto the surface of the cathode roller to form a copper foil, the thickness of the copper foil being controlled by the cathode current density and the rotating speed of the cathode roller, and those skilled in the art can control the current density and the rotating speed of the cathode roller by using conventional methods to obtain a copper foil with a target thickness. After the copper foil is turned out of the solution with the roller, it is continuously peeled off from the cathode roller, washed with water, passivated, dried, and coiled to form an electrolytic copper foil.

[0160] Example 3

[0161] 1) Preparation of cathode electrically insulated mask points

[0162] Direct forming method is used to prepare electrically insulated mask points with rectangular array on the surface of rotating cathode roller. The electrically insulated mask points use a circle, i.e. a = b = 400 μm, A = B = 1000 μm, and the electrically insulated material uses ultraviolet light curing material.

[0163] 2) Electrolysis

[0164] Copper wire with copper content of 99.99% is dissolved in sulfuric acid to form a sulfuric acid-copper sulfate solution, and then organic additives and hydrochloric acid are added and stirred uniformly to obtain an initial electrolyte. The electrolyte is filtered using a filter with a filtration precision of less than 0.5 μm to obtain a pure electrolyte. The cathode uses a cathode roller, and the anode uses a titanium plate with an iridium tantalum coating on the surface. The anode and the cathode are separated by the electrolyte, and the anode-cathode distance is 8 mm.

[0165] Among them, the concentration of sulfuric acid in the electrolyte is 110 g / L, the concentration of copper ions is 90 g / L, the concentration of chloride ions is 28 mg / L, the concentration of sodium polydithiopropane sulfonate is 45 mg / L, the concentration of sodium N,N-dimethyl-dithioformamide propyl sulfonate is 28 mg / L, the concentration of polyethylene glycol (molecular weight 4000-6000) is 7 mg / L, the concentration of hydroxyethyl cellulose is 2 mg / L, the concentration of collagen is 1 mg / L, the concentration of 2-amino-4-methylbenzothiazole is 4 mg / L, and the current density is 6500 A / m 2 . A porous copper foil with a thickness of 6 μm is prepared, the electrolyte temperature is 53 ℃, and the electrolyte flow rate is 45 m 3 / h.

[0166] The cathode roller rotates at a constant speed, and the copper in the solution is deposited on the surface of the cathode roller to form a copper foil. The thickness of the copper foil is controlled by the cathode current density and the rotation speed of the cathode roller. Those skilled in the art can use conventional methods to control the current density and the rotation speed of the cathode roller to obtain a copper foil with a target thickness. After the copper foil is removed from the roller, it is continuously peeled off from the cathode roller, washed with water, passivated, dried, and wound to form an electrolytic copper foil.

[0167] Example 4

[0168] 1) Preparation of cathode electrically insulated mask points

[0169] Template method is used to prepare electrically insulated mask points with rectangular array on the surface of rotating cathode roller. The electrically insulated mask points use a circle, i.e. a = b = 500 μm, A = B = 1000 μm, and the electrically insulated material uses ultraviolet light curing material.

[0170] 2) Electrolysis

[0171] Copper wire with copper content of 99.99% is dissolved in sulfuric acid to form a sulfuric acid-copper sulfate solution, and then organic additives and hydrochloric acid are added and stirred uniformly to obtain an initial electrolyte. The electrolyte is filtered using a filter with a filtration precision of less than 0.5 μm to obtain a pure electrolyte. A cathode roller is used as the cathode, and a titanium plate with an iridium-tantalum coating on the surface is used as the anode. The anode and the cathode are separated by the electrolyte, and the anode-cathode distance is 8 mm.

[0172] The concentration of sulfuric acid in the electrolyte is 105 g / L, the concentration of copper ions is 92 g / L, the concentration of chloride ions is 28 mg / L, the concentration of 3-mercapto propane sulfonic acid sodium is 50 mg / L, the concentration of N,N-dimethyl-dithioformamide propyl sulfonic acid sodium is 20 mg / L, the concentration of polyethylene glycol (molecular weight 4000-6000) is 5 mg / L, the concentration of hydroxyethyl cellulose is 6 mg / L, the concentration of collagen is 3 mg / L, the concentration of 2-amino-4-methyl benzothiazole is 10 mg / L, and the current density is 7000 A / m 2 A porous copper foil with a thickness of 6 μm is prepared, the temperature of the electrolyte is 55 °C, and the flow rate of the electrolyte is 45 m 3 / h.

[0173] The cathode roller rotates at a constant speed, and copper in the solution is deposited onto the surface of the cathode roller to form a copper foil. The thickness of the copper foil is controlled by the cathode current density and the rotation speed of the cathode roller. Those skilled in the art can control the current density and the rotation speed of the cathode roller using conventional methods to obtain a copper foil with a target thickness. After the copper foil is removed from the solution along with the roller, it is continuously peeled off from the cathode roller, washed with water, passivated, dried, and wound to form an electrolytic copper foil.

[0174] Example 5

[0175] Example 4 is basically the same, except that A = B = 800 μm.

[0176] Example 6

[0177] Example 1 is basically the same, except that a = b = 400 μm.

[0178] Example 7

[0179] Example 3 is basically the same, except that a = b = 500 μm and A = B = 500 μm.

[0180] Example 8

[0181] Example 2 is basically the same, except that a = b = 600 μm and A = B = 500 μm.

[0182] Comparative Example 1

[0183] The procedure is substantially the same as in Example 1, except that the preparation of the electrically insulating shield point is not performed on the cathode.

[0184] Test section

[0185] 1) Tensile strength and elongation test of electrolytic copper foil

[0186] The tensile strength and elongation of the electrolytic copper foil were tested according to the test method GB / T 29847-2013 using a HY-0230 universal material testing machine manufactured by Shanghai Hengyi Precision Instrument Co., Ltd. at a strain rate of 0.8 mm / s and room temperature (about 25°C). The tensile test sample was a strip-shaped sample with a total length of 100 mm and a width of 15 mm. The sample was measured three times and the average value was taken as the final tensile strength and elongation of the sample.

[0187] 2) Coulombic efficiency

[0188] Half-cell assembly and test: The test was carried out by assembling a CR2032 button cell, and the assembly of the battery was completed in an argon glove box. The electrolytic copper foil prepared in Examples 1-8 was used as the working electrode, lithium sheet as the counter electrode, and the commercially available electrolyte and separator were assembled into a half-cell. The CT-3008W5V20A-TF high-precision battery performance test system was used for constant current charge and discharge test, and the half-cell was cycled at a current density of 1 mA / cm 2 for 200 cycles. The final coulombic efficiency was calculated.

[0189] 3) Cycle capacity retention rate 1

[0190] Full cell 1 assembly and test: The commercially available silicon-carbon negative active material 90 parts, conductive agent 4 parts, and binder 6 parts were mixed in high-purity water to prepare a slurry. Then, the slurry was uniformly coated on the smooth surface of the electrolytic copper foil prepared in Examples 1-8 using a coater, and then the slurry was dried in an oven. Then, the slurry was uniformly coated on the rough surface of the electrolytic copper foil prepared in Examples 1-8 using a coater, and then the slurry was dried in an oven. After drying, the negative electrode sheet was rolled. Then, the obtained negative electrode sheet, commercially available electrolyte (1 mol / L LiPF6 in EC-DEC (volume ratio 1:1)), separator and positive electrode sheet were assembled to produce a CR2032 type button cell. The CT-3008W5V20A-TF high-precision battery performance test system was used for constant current charge and discharge test, and the battery was cycled at a rate of 1C for 100 times. The cycle capacity retention rate of the battery after 100 cycles was tested, and the cycle capacity retention rate represented the percentage of the battery capacity after the final cycle discharge to the battery capacity after the first discharge.

[0191] 4) Cycle capacity retention rate 2

[0192] Full battery 2 assembly and test: In the inert gas argon environment, the 20 μm thick lithium foil is placed on the smooth surface and the rough surface of the electrolytic copper foil prepared in examples 1-8 respectively, the lithium foil and the copper foil are compounded by rolling, the copper-lithium composite foil is used as the negative electrode, the commercial positive electrode sheet is used as the positive electrode to assemble the full battery, the battery specification is CR2032 type, and the electrolyte uses sulfide solid-state electrolyte. CT-3008W5V20A-TF high-precision battery performance test system is used for constant current charge and discharge test, 1C rate is used for 100 times of charge and discharge cycle of the battery, and the cycle capacity retention rate of the battery after 100 times of cycle is tested.

[0193] 5) Wettability test

[0194] According to weight, 90 parts of commercially available silicon-carbon negative electrode active material, 4 parts of conductive agent and 6 parts of binder are mixed in high-purity water to prepare slurry. Then, the slurry is uniformly coated on the smooth surface of the electrolytic copper foil prepared in examples 1-3 using a coater, and then the slurry is dried in an oven. Then, the slurry is uniformly coated on the rough surface of the electrolytic copper foil prepared in examples 1-3 using a coater, and then the slurry is dried in an oven. After drying, the electrode sheet is obtained by rolling.

[0195] The wettability of the electrolyte on the electrode sheet is tested by using a Data-physics OCA20 contact angle / surface tension measuring instrument. The contact angle of the electrolyte droplet on the electrode sheet surface after 1s is used to characterize the wettability. The smaller the contact angle, the faster and more fully the electrolyte can wet the electrode sheet, so that the negative electrode active material can fully contact with the electrolyte. In the use process of the battery, the Li + is provided with a fast transportation channel, so that the Li + is embedded and extracted in the active material more quickly.

[0196] The above test results are shown in Table 1 as follows:

[0197] Table 1

[0198] The above test results show that the electrolytic copper foil provided by the application can improve the wettability of the electrolyte, and also can improve the coulombic efficiency and cycle capacity retention rate of the battery. The high and low of the coulombic efficiency and cycle capacity retention rate can characterize the strength of the adhesion between the negative electrode active material and the copper foil current collector. As the negative electrode current collector, it is particularly suitable for solid-state batteries.

[0199] The above description of various embodiments tends to emphasize the differences between various embodiments, and the same or similar parts can be referred to each other. For the sake of brevity, the same or similar parts are not described herein.

[0200] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A novel electrolytic copper foil, characterized by, The copper layer includes at least one copper layer, and a through-hole array is arranged on at least part of the surface of the copper layer, the through-hole array is formed by M*N through-holes arranged in M rows and N columns, M is greater than or equal to 1, N is greater than or equal to 1, M and N are positive integers, each row of through-holes in the through-hole array is arranged along the x direction, each column of through-holes in the through-hole array is arranged along the y direction, the x direction intersects with the y direction and is located in the same plane, and the z direction is the thickness direction of the copper layer, and the z direction is perpendicular to the x direction and the y direction. The thickness of the copper layer is denoted as h, the longest distance from the center point of the via to the edge of the via is the length of the major axis, denoted as a, the shortest distance from the center point of the via to the edge of the via is the length of the minor axis, denoted as b, the shortest perpendicular distance between adjacent vias along the x direction is denoted as A, the shortest perpendicular distance between adjacent vias along the Y direction is denoted as B, the Y direction is perpendicular to the x direction, the surface area of the copper layer covered by the via array is the array region, the surface area of the copper layer not covered by the via array is the non-array region, and the weight per square meter of the array region is denoted as m, then: Wherein, k is any value between 0.9 and 1.

1.

2. The electrolytic copper foil according to claim 1, characterized by A is 200-2000 μm, and optionally 400-1500 μm, and / or B is 200-2000 μm, and optionally 400-1500 μm.

3. The electrolytic copper foil according to claim 1, characterized by a is 100-1500 μm, and optionally 200-1000 μm, and / or b is 100-1500 μm, and optionally 200-1000 μm.

4. The electrolytic copper foil according to claim 1, characterized by The porosity of the array region is 5%-50%, and optionally 10%-40%.

5. The electrolytic copper foil according to claim 1, characterized by The through-hole array is arranged in a rectangular array and / or a diamond array.

6. The electrolytic copper foil according to claim 1, characterized by The through-holes are circular and / or elliptical.

7. The electrolytic copper foil according to claim 1, characterized by The copper layer has two opposite surfaces in the thickness direction of the copper layer, the two surfaces are respectively a first surface and a second surface, and the surface roughness and / or brightness of the first surface and the second surface are different.

8. The electrolytic copper foil according to claim 1, characterized by The thickness of the copper layer is 3 μm-15 μm.

9. The electrolytic copper foil according to any one of claims 1 to 8, characterized by the tensile strength of the array region of the copper layer at normal temperature is 15 kgf / mm 2 -30 kgf / mm 2 the tensile strength of the non-array region of the copper layer at normal temperature is 30 kgf / mm 2 -70 kgf / mm 2 the normal temperature is 25±5℃.

10. A method of producing the electrolytic copper foil according to any one of claims 1 to 9, characterized by, The method comprises the following steps: An anode and a cathode to be plated are placed in an electrolyte to perform electrolysis to obtain an electrolytic copper foil, wherein the cathode has array-arranged electrically insulating shielding points.

11. The method of claim 10, wherein, The electrolyte comprises copper ions, sulfuric acid, halogen ions and an organic additive; Optionally, the concentration of the copper ions in the electrolyte is 70 g / L-130 g / L; Optionally, the concentration of the sulfuric acid in the electrolyte is 80 g / L-150 g / L; Optionally, the concentration of the halogen ions in the electrolyte is 15 mg / L-50 mg / L; Optionally, the concentration of the organic additive in the electrolyte is 20 mg / L-500 mg / L.

12. The method of producing electrolytic copper foil according to claim 11, characterized by, The organic additive comprises a leveling agent, a brightener and a wetting agent, The leveling agent is a nitrogen-containing compound, and optionally comprises one or more of collagen, gelatin, thiourea, allyl thiourea, ethylene thiourea and 2-amino-4-methylbenzothiazole, and optionally the mass concentration of the leveling agent in the electrolyte is 0.1 mg / L-40 mg / L; and / or The brightener is an organic divalent sulfide, and optionally comprises one or more of polydithiopropanesulfonic acid sodium, N,N-dimethyl-dithioformamide sodium, 3-mercapto propane sulfonic acid sodium, 3-(benzothiazole-2-mercapto) propane sulfonic acid sodium and isothiouronium propyl sulfonate, and optionally the mass concentration of the brightener in the electrolyte is 0.1 mg / L-400 mg / L; and / or The brightener is an organic divalent sulfide, and optionally comprises one or more of polydithiopropanesulfonic acid sodium, N,N-dimethyl-dithioformamide sodium, 3-mercapto propane sulfonic acid sodium, 3-(benzothiazole-2-mercapto) propane sulfonic acid sodium and isothiouronium propyl sulfonate, and optionally the mass concentration of the brightener in the electrolyte is 0.1 mg / L-400 mg / L; and / or The wetting agent is a polyether compound, optionally including one or more of polyethylene glycol, hydroxyethyl cellulose, polypropylene glycol, allyl polyethylene glycol, fatty amine polyoxyethylene ether, and optionally the mass concentration of the wetting agent in the electrolyte is 1 mg / L-40 mg / L.

13. The method of producing electrolytic copper foil according to claim 10, characterized by, The temperature of the electrolyte during the electrolysis process is 45-60°C.

14. A negative electrode sheet characterized by comprising: The electrolytic copper foil according to any one of claims 1-9, or the electrolytic copper foil prepared by the method according to any one of claims 10-13.

15. A secondary battery characterized by comprising: The negative electrode sheet according to claim 14.

16. The secondary battery according to claim 15, characterized by The secondary battery is a liquid, semi-solid or solid battery.

17. An electrical device, comprising: At least one of the secondary batteries according to claim 16. At least one of the secondary batteries according to claim 16.

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