TWI830347B - Electrolytic copper foil, electrode and lithium ion battery comprising the same - Google Patents

Abstract

Provided are an electrolytic copper foil, an electrode and a lithium ion battery comprising the same. The electrolytic copper foil has a first surface and a second surface opposite the first surface, wherein the first surface and the second surface are analyzed by GIXRD, the first surface and the second surface each have an intensity of a characteristic peak of crystal face (111) denoted by I₁, an intensity of a characteristic peak of crystal face (200) denoted by I₂, an intensity of a characteristic peak of crystal face (220) denoted by I₃, a full width at half maximum (FWHM) of the characteristic peak of crystal face (111) denoted by W₁, and a full width at FWHM of the characteristic peak of crystal face (200) denoted by W₂. The first surface and the second surface both meet the conditions of (I₁+I₂)/(I₁+I₂+I₃) of 0.83 or more and (W₁+W₂) of 0.80° or less. By controlling aforesaid technical features, the electrolytic copper foil has higher corrosion resistance and the lithium ion battery has higher safety.

Description

Electrolytic copper foil and electrodes and lithium ion batteries containing the same

The present disclosure relates to an electrolytic copper foil, and in particular, to an electrolytic copper foil that can be used in lithium-ion batteries, an electrode including the same, and a lithium-ion battery.

Copper foil has good electrical conductivity and has the advantage of low cost compared to precious metals such as silver. Therefore, it is not only widely used in basic industries, but also an important raw material for advanced technology industries; for example, copper foil can be used as a lithium ion Battery electrode materials are widely used in portable electronic devices (PED), electric vehicles (EV), energy storage systems (ESS) and other fields.

When copper foil is used in lithium-ion batteries as electrode materials, because the electrolyte in the lithium-ion battery is corrosive to the copper foil, as the battery operation hours increase, the electrolyte will corrode the copper foil in the long run, thereby shortening the life of the lithium-ion battery. The cycle life will also reduce the reliability of lithium-ion batteries and raise safety concerns.

In view of this, attempts are currently being made to perform corrosion-resistant treatment on copper foil in the hope of suppressing or reducing the aforementioned problems. Common corrosion-resistant treatments can be divided into covering layer protection and corrosion inhibitor protection. Covering layer protection is to coat the surface of the copper foil with a layer of corrosion-resistant material or electroplating a metal layer with high corrosion resistance. However, the above treatment needs to consider the bonding strength of the corrosion-resistant material layer, the metal layer with high corrosion resistance and the copper foil. Once the aforementioned layer peels off, Copper foil will still be directly Corroded; although corrosion inhibitor protection has the advantages of low dosage and good effect, its application is highly restricted. In addition to not being suitable for long-term operation at high temperatures, it can only be used in closed circulation systems.

Therefore, it is still necessary to actively seek other technical means to improve the corrosion resistance of copper foil to enhance the safety of lithium-ion batteries.

In view of the shortcomings of the existing technology, the purpose of this disclosure is to improve the conventional copper foil so that it can have good corrosion resistance, especially can effectively resist the erosion of electrolyte.

In order to achieve the aforementioned objectives, the present disclosure provides an electrolytic copper foil, which has a first surface and a second surface located on opposite sides. The first surface and the second surface are analyzed by low grazing angle X-ray diffraction (GIXRD). The first surface and the second surface each have a characteristic peak signal intensity I ₁ of the (111) crystal plane, a characteristic peak signal intensity I ₂ of the (200) crystal plane, a characteristic peak signal intensity I ₃ of the (220) crystal plane, and (111). ) The characteristic peak half-maximum width W ₁ of the (200) crystal plane and the characteristic peak half-maximum width W ₂ of the (200) crystal plane; wherein, the first surface and the second surface both meet the following conditions: (I ₁ +I ₂ )/( The value of I ₁ +I ₂ +I ₃ ) is 0.83 or more, and the value of (W ₁ +W ₂ ) is 0.80° or less.

The present disclosure controls the characteristic peak signal intensity I ₁ of the (I11) crystal plane of the first and second surfaces of the electrolytic copper foil, the characteristic peak signal intensity I ₂ of the (200) crystal plane, and the characteristics of the (220) crystal plane. The peak signal intensity I ₃ , the characteristic peak half-maximum width W ₁ of the (111) crystal plane, and the characteristic peak half-maximum width W ₂ of the (200) crystal plane make both the first surface and the second surface consistent with (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) is more than 0.83, and (W ₁ +W ₂ ) is less than 0.80°, which can specifically improve the corrosion resistance of electrolytic copper foil, thereby increasing the number of lithium ions used in subsequent applications. Battery safety.

In addition, the yield strength of the electrolytic copper foil can be greater than 230 MPa; preferably, the yield strength of the electrolytic copper foil can be 231 MPa to 300 MPa; more preferably, the yield strength of the electrolytic copper foil Voltage strength can range from 231MPa to 270MPa. By further controlling the yield strength of the electrolytic copper foil to be greater than 230MPa, the present disclosure can enable the lithium-ion battery including the electrolytic copper foil to have a better cycle life.

Preferably, the first surface and the second surface of the electrolytic copper foil meet the following conditions: (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) value can be 0.84 to 1.00; more preferably, The value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) can be 0.84 to 0.95. In one embodiment, the value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) in the first surface of the electrolytic copper foil can be 0.85 to 0.95, and the third surface of the electrolytic copper foil In the two surfaces, the value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) can be 0.84 to 0.92. The present disclosure can specifically improve the corrosion resistance of the electrolytic copper foil by adjusting the intensity ratio of the characteristic peaks of the (111) crystal plane and the (200) crystal plane of the electrolytic copper foil.

Preferably, the first surface and the second surface of the electrolytic copper foil meet the following conditions: (W ₁ + W ₂ ) can have a value of 0.25° to 0.75°; more preferably, the value of (W ₁ + W ₂ ) Can be 0.28° to 0.74°. In one embodiment, the value of (W ₁ +W ₂ ) on the first surface of the electrolytic copper foil can be 0.28° to 0.74°, and the value of (W ₁ +W ) on the second surface of the electrolytic copper foil ₂ ) The value can be from 0.43° to 0.65°.

In one embodiment, the root mean square height (Sq) of the first surface of the electrolytic copper foil can be 0.20 microns to 0.55 microns; by controlling the Sq of the first surface of the electrolytic copper foil to be 0.20 microns to 0.55 microns can improve the coating quality of active materials on electrolytic copper foil, making it suitable as an electrode material for lithium-ion batteries, and enabling lithium-ion batteries containing such electrolytic copper foil to have high capacity. advantage. In another embodiment, Sq of both the first surface and the second surface of the electrolytic copper foil can be 0.20 microns to 0.55 microns. In yet another embodiment, the Sq of the first surface of the electrolytic copper foil may be 0.20 μm to 0.55 μm, and the Sq of the second surface of the electrolytic copper foil may be 0.25 μm to 0.50 μm.

In one embodiment, the absolute difference between Sq of the first surface of the electrolytic copper foil and Sq of the second surface can be less than 0.15 microns; in another embodiment, the Sq of the first surface of the electrolytic copper foil The absolute difference between Sq and Sq of the second surface may be less than 0.145 microns.

In one embodiment, the thickness of the electrolytic copper foil can be 4 microns to 20 microns; in another embodiment, the thickness of the electrolytic copper foil can be 6 microns to 20 microns.

The present disclosure further provides an electrode for a lithium-ion battery, which includes the aforementioned electrolytic copper foil.

The present disclosure also provides a lithium-ion battery, which includes the aforementioned electrode.

According to the present disclosure, the electrolytic copper foil can be used as a negative electrode of a lithium-ion battery and can also be used as a positive electrode of a lithium-ion battery. The electrolytic copper foil can be suitable for use as a current collector, and at least one layer of active material is coated on one or both sides of the electrolytic copper foil to form an electrode of a lithium ion battery.

According to the present disclosure, active materials can be divided into positive active materials and negative active materials. The negative active material contains a negative active material, which can be a carbon-containing material, a silicon-containing material, a silicon-carbon composite, a metal, a metal oxide, a metal alloy or a polymer; preferably it is a carbon-containing material or a silicon-containing material, but Not limited to this. Specifically, the carbon-containing substance can be mesophase graphite powder (MGP), non-graphitizing carbon, coke, graphite, glasslike carbon (glasslike) carbon), carbon fiber, activated carbon, carbon black or polymer calcined material, but not limited thereto; wherein, coke includes pitch coke, needle coke or petroleum coke, etc.; the The calcined polymer is obtained by firing high polymers such as phenol-formaldehyde resin or furan resin at appropriate temperatures so that they are carbonated. The silicon-containing material has an excellent ability to form an alloy with lithium ions and an excellent ability to extract lithium ions from the alloy lithium. Moreover, when the silicon-containing material is used in a lithium-ion secondary battery, the advantage of having a large energy density can be achieved; Silicon substances can be combined with cobalt (Co), iron (Fe), tin (Sn), nickel (Ni), copper (Cu), manganese (Mn), zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), chromium (Cr), ruthenium (Ru), molybdenum (Mo) or a combination thereof to form an alloy material. The element of the metal or metal alloy may be selected from the group consisting of: cobalt, iron, tin, nickel, copper, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, chromium, ruthenium and molybdenum , but not limited to this. An example of the metal oxide is trioxide Ferrous oxide, ferric tetroxide, ruthenium dioxide, molybdenum dioxide and molybdenum trioxide, but are not limited to these. Examples of the polymer are polyacetylene and polypyrrole, but are not limited thereto.

In one embodiment, the active material can be added with auxiliary additives as needed, and the auxiliary additives can be binders and/or weak acid reagents, but are not limited to this. Preferably, the binder can be polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (poly( acrylic acid (PAA), polyacrylonitrile (PAN) or polyacrylate (polyacrylate). The weak acid reagent can be oxalic acid, citric acid, lactic acid, acetic acid or formic acid.

According to the disclosure, depending on the composition of the positive electrode slurry, the lithium-ion battery of the disclosure can be a lithium cobalt battery (LiCoO ₂ battery), a lithium nickel battery (LiNiO ₂ battery), a lithium manganese battery (LiMn ₂ O ₄ battery), _{Lithium cobalt nickel} battery ( _LiCo

According to the present disclosure, the electrolyte may include a solvent, an electrolyte, or optional additives. Solvents in the electrolyte include non-aqueous solvents, such as cyclic carbonates such as ethylene carbonate (EC) or propylene carbonate (PC); dimethyl carbonate (DMC), carbonic acid Chain carbonates such as diethyl carbonate (DEC) or ethyl methyl carbonate (EMC); or sultones (sultones), but are not limited to this; the aforementioned solvents can be used alone It is also possible to use two or more solvents in combination. Electrolytes include: lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(oxalate)borate ) and lithium bis(trifluoromethane sulfonimide), but are not limited to this.

In other embodiments, solid electrolytes can be used in lithium-ion batteries to replace the above-mentioned electrolytes; for example, the solid electrolytes can be crystalline electrolytes, glassy electrolytes, glass-ceramic electrolytes or polymer electrolytes. But it is not limited to this. Specifically, the crystalline electrolyte can be a sulfide solid electrolyte such as lithium superion conductor (LISICON) type or Argyrodite type; or it can be a garnet structure type (Garnet type) or a perovskite structure type. (Peroskite type), NASICON structural type, etc. oxide solid electrolytes, but are not limited thereto. The glassy electrolyte may be a glassy solid electrolyte such as oxide or sulfide, but is not limited thereto. The glass ceramic electrolyte may be a glass ceramic solid electrolyte such as oxide or sulfide, but is not limited thereto. The polymer electrolyte can be a pure solid polymer electrolyte such as polyethylene oxide-based (PEO-based), polypropylene oxide-based (PPO-based), etc.; or it can be a polyacrylonitrile-based electrolyte. (polyacrylonitrile-based, PAN series), polymethyl methacrylate-based (poly(methyl methacrylate)-based, PMMA series), polyvinyl chloride-based (poly(vinyl chloride)-based, PVC series), polyvinylidene fluoride Colloidal polymer electrolytes such as ethylene-based (poly(vinylidene fluoride)-based, PVDF-based), but are not limited thereto.

According to the present disclosure, the lithium-ion battery may be a stacked lithium-ion battery including negative electrodes and positive electrodes stacked through a separator film, or it may be a spiral-wound stacked lithium-ion battery including continuous electrodes and separators spirally wound together. , but not limited to this. According to different application products, the lithium-ion battery disclosed in the present disclosure can be used in notebook personal computers, mobile phones, electric vehicles, and energy storage systems, and can be made into, for example, cylindrical secondary batteries, prismatic secondary batteries, pouch-shaped secondary batteries, or button-shaped secondary batteries. Secondary batteries, but not limited to this.

In this specification, unless otherwise stated, the process conditions, numerical values or numerical ranges stated in this specification can be understood to be expressed by the term "about". Said "about" may be expressed to within ±5% of the stated value.

10:Electrolytic deposition device

11:Cathode roller

12:Insoluble anode plate

121: Anode surface

13: Copper electrolyte

14:Feeding pipe

20: Anti-rust treatment device

21: Anti-rust treatment tank

211a, 211b: Plate

31:First guide roller

32:Second guide roller

33:Third guide roller

34:Fourth guide roller

35:Fifth guide roller

36:Sixth guide roller

40:Air knife

50: Medium wave infrared processing device

60:Electrolytic copper foil

61: Copper layer

611: Deposition surface

612:Roller surface

62: First anti-rust layer

621: First surface

63: Second anti-rust layer

631: Second surface

Figure 1 is a schematic diagram of the production flow of electrolytic copper foils of Examples 1 to 12 and Comparative Examples 1 to 5.

2 is a side view of the electrolytic copper foils of Examples 1 to 12 and Comparative Examples 1 to 5.

Below, several examples are enumerated to illustrate the implementation of electrolytic copper foil, and several comparative examples are provided as comparisons. Those with ordinary knowledge in the art can easily understand the advantages that can be achieved by the present disclosure through the content of the following examples and comparative examples. and effect. It should be understood that the embodiments listed in this specification are only used to illustrate the implementation of the present disclosure, and are not intended to limit the scope of the present disclosure. Those with ordinary knowledge in the technical field can make decisions based on common knowledge without departing from the present disclosure. Various modifications and changes may be made in order to implement or apply the contents of this disclosure.

As shown in Figure 1, the equipment for producing electrolytic copper foil includes an electrolytic deposition device 10, an anti-rust treatment device 20 and a series of guide rollers. The electrolytic deposition device 10 includes a cathode roller 11 , an insoluble anode plate 12 , a copper electrolyte 13 and a feed tube 14 . The cathode roller 11 is a rotatable titanium cathode roller. The insoluble anode plate 12 is an IrO ₂ coated titanium plate, which is disposed below the cathode roller 11 and substantially surrounds the lower half of the cathode roller 11 . The insoluble anode plate 12 has a surface facing the cathode roller. Anode surface 121 of barrel 11 . The cathode roller 11 and the insoluble anode plate 12 are spaced apart from each other to accommodate the copper electrolyte 13 introduced through the feed pipe 14 . The anti-rust treatment device 20 includes an anti-rust treatment tank 21 and two sets of electrode plates 211a and 211b arranged therein. A series of guide rollers includes a first guide roller 31, a second guide roller 32, a third guide roller 33, a fourth guide roller 34, a fifth guide roller 35 and a sixth guide roller 36, which can transport the electrolytically deposited original material. The foil is sent to the anti-rust treatment device 20 for anti-rust treatment. After the original foil is anti-rust treated, the excess anti-rust material on the surface is removed with an air knife 40, and then annealed by the mid-wave infrared treatment device 50, and finally in the sixth channel The electrolytic copper foil 60 is obtained by winding up on the roller 36 .

The electrolytic copper foil disclosed in the present disclosure can adjust the electrolytic deposition parameters in the process according to needs. In one embodiment, the copper electrolyte formula in the electrolytic deposition step may include copper sulfate, sulfuric acid, chloride ions, sodium 3-mercapto-1-propanesulfonate (MPS) and polyoxyethylene sorbitan fatty acid ester (Tween 20), but is not limited to this; in the embodiment, the copper sulfate concentration can be from 200 grams/liter (g/L) to 400g/L, the sulfuric acid concentration can be 80g/L to 150g/L, the chloride ion concentration can be 20ppm to 60ppm, the sodium 3-mercapto-1-propanesulfonate concentration can be 20ppm to 30ppm, polyoxyethylene sorbitol fatty acid ester The concentration can be 20 ppm to 60 ppm; the temperature of the copper electrolyte in the electrolytic deposition step can be 40°C to 50°C, and the current density can be 40 A/dm ² to 50A/dm ² .

The characteristics of the electrolytic copper foil disclosed in the present disclosure can adjust the copper electrolyte formula and related process parameters in the electrolytic deposition step according to needs. For example, by adjusting the amount of polyoxyethylene sorbitol fatty acid ester added to the copper electrolyte, or adjusting the roughness of the anode plate of the electrolytic deposition device, the crystalline form, yield strength and root mean square height of the crystal grains of the electrolytic copper foil can be controlled , but not limited to this.

The electrolytic copper foil disclosed in the present disclosure can be electroplated and anti-rust treated according to requirements. The anti-rust liquid used can be chromium anti-rust liquid, nickel anti-rust liquid, zinc anti-rust liquid, tin anti-rust liquid, but is not limited thereto. In one implementation, the anti-rust liquid can be a chromium anti-rust liquid, the chromic acid concentration can be 1.5g/L to 5.0g/L, the current density can be 0.5A/dm ² to 6.0A/dm ² , and the chromium The liquid temperature of the anti-rust liquid can be 20°C to 40°C, and the anti-rust treatment time can be 2 seconds to 4 seconds.

The electrolytic copper foil disclosed in the present disclosure can be subjected to mid-wave infrared annealing treatment according to requirements. As shown in Figure 1, after the anti-rust treated raw foil is removed by the air knife 40 to remove excess anti-rust material on the surface, it can be further annealed in the mid-wave infrared treatment device 50, and then rolled up on the sixth guide roller 36. Electrolytic copper foil 60 was obtained. In one embodiment, the mid-wave infrared annealing treatment can be applied to one or both sides of the electrolytic copper foil. The filament temperature of the mid-wave infrared annealing treatment can be 1500°C to 1800°C. The maximum wavelength of the mid-wave infrared annealing treatment device Can be 1.4 micron to 1.8 micron, medium wave infrared annealing device and electrolytic copper The foil distance can be from 30 mm to 60 mm, and the annealing time can be from 5 seconds to 15 seconds. The crystalline form, yield strength and root mean square height of the crystal grains of the electrolytic copper foil can be adjusted through the mid-wave infrared annealing treatment time, but are not limited to this.

"Electrolytic Copper Foil"

Examples 1 to 12

In Examples 1 to 12, the production equipment shown in Figure 1 is used, and electrolytic copper foil is produced through substantially the same electrolytic deposition steps, anti-rust treatment steps and mid-wave infrared annealing steps in sequence. The methods of manufacturing the electrolytic copper foil 60 of Examples 1 to 12 are collectively described below.

First, the copper electrolyte 13 for the electrolytic deposition step is prepared. During the electrolytic deposition step, the cathode roller 11 rotates at a fixed axis at a constant speed, and current is applied to the cathode roller 11 and the insoluble anode plate 12 so that the copper electrolyte The copper ions in 13 are deposited on the surface of the cathode roller 11 to form an original foil, and then the original foil is peeled off from the cathode roller 11 and guided to the first guide roller 31 .

Here, the formula of copper electrolyte 13 and the process conditions of electrolytic deposition are as follows:

I. Formula of copper electrolyte 13: copper sulfate (CuSO ₄ .5H ₂ O): about 320g/L; sulfuric acid: about 110g/L; chloride ion: about 25ppm; sodium 3-mercapto-1-propanesulfonate (purchased From HOPAX): about 20ppm; polyoxyethylene sorbitol fatty acid ester (Tween 20): content is shown in Table 1 below.

II. Electrolytic deposition process conditions: temperature of copper electrolyte 13: about 50°C; anode surface roughness (Rz): as shown in Table 1 below; and current density: about 50A/dm ² .

Among them, the roughness (Rz) of the anode surface refers to the maximum height measured according to the JIS B 0601-1994 standard method. Here, the instruments and conditions selected to measure Rz on the anode surface are as follows:

I. Measuring instrument: Portable surface roughness measuring instrument (contact type): SJ-410, purchased from Mitutoyo.

II. Measurement conditions: tip radius: 2 microns; tip angle: 60°; cut off length (λc): 0.8 mm; and evaluation length: 4 mm.

Subsequently, the original foil is transported to the anti-rust treatment device 20 through the first guide roller 31 and the second guide roller 32 for anti-rust treatment. The original foil is immersed in the anti-rust treatment tank 21 filled with chromium anti-rust liquid, and then passes through the third During the transportation of the guide roller 33, two sets of electrode plates 211a and 211b are used to perform anti-rust treatment on the opposite surfaces of the original foil, and a first anti-rust layer and a second anti-rust layer are electrolytically deposited on the opposite surfaces of the original foil. .

Here, the formula of chromium anti-rust liquid and the process conditions of anti-rust treatment are as follows:

I. Formula of chromium anti-rust liquid: chromic acid (CrO ₃ ): about 1.5g/L.

II. Process conditions for anti-rust treatment: liquid temperature: 25°C; current density: about 0.5A/ ^dm2 ; and treatment time: about 2 seconds.

After the anti-rust treatment is completed under the above conditions, the anti-rust treated copper foil is guided to the fourth guide roller 34, and the air knife 40 is used to remove excess anti-rust material on the surface and dry it, and then through the fifth guide roller 34. The roller 35 is transported through the medium-wave infrared treatment device 50 to anneal its two surfaces, and is rolled up on the sixth guide roller 36 to obtain the electrolytic copper foil 60 .

Here, the annealing process conditions are as follows:

I. Equipment parameters of medium wave infrared processing device: lamp diameter: 23×11 mm/34×14 mm; filament temperature: 1600±10℃; maximum wavelength: 1.4 microns to 1.8 microns; maximum power: 120 kilowatts/square Meters (kW/m ² ); and maximum line power density: 80 Watts/centimeter (W/cm).

II. Annealing process parameters: distance between lamp tube and electrolytic copper foil to be annealed: 45 mm; power: 95%; and annealing treatment time: as shown in Table 1 below.

According to the above manufacturing method, the electrolytic copper foils of Examples 1 to 8, 11 to 12 with a thickness of about 6 microns, Example 9 with a thickness of about 4 microns, and Example 10 with a thickness of about 20 microns can be produced respectively. The differences between Examples 1 to 12 mainly lie in the thickness of the electrolytic copper foil, the polyoxyethylene sorbitol fatty acid ester content of the copper electrolyte used, the roughness of the anode surface during the electrolytic deposition step, and the annealing treatment time. As shown in FIG. 2 , the electrolytic copper foil 60 of each embodiment includes a copper layer 61 (equivalent to the original foil without the aforementioned anti-rust treatment step), a first anti-rust layer 62 and a second anti-rust layer 63. The copper layer 61 It includes a deposited side (deposited side) 611 and a drum side (drum side) 612 located on the opposite side. During the electrolytic deposition process, the deposited side 611 is the surface of the original foil facing the insoluble anode plate, and the drum side 612 is the original foil and the cathode. The surface in contact with the roller; the first anti-rust layer 62 is formed on the deposition surface 611 of the copper layer 61. The first anti-rust layer 62 has a first surface 621 located on the outermost side, and the second anti-rust layer 63 is formed on the copper layer. 61 on the roller surface 612, and the second anti-rust layer 63 has a second surface 631 located on the outermost side. The first surface 621 and the second surface 631 are the two outermost surfaces of the electrolytic copper foil 60 located on the opposite side. .

Comparative Examples 1 to 5

Comparative Examples 1 to 5 are used as controls for Examples 1 to 12, which generally adopt the same preparation method as Examples 1 to 12, except that the thickness of the electrolytic copper foil obtained in each comparative example, the polyoxyethylene sorbide content of the copper electrolyte used The content of alcohol fatty acid esters, the roughness of the anode surface in the electrolytic deposition step, and the annealing treatment time are all different. The above parameters are listed in Table 1. In addition, the structures of the electrolytic copper foils of Comparative Examples 1 to 5 are also shown in Figure 2 shown, and their thicknesses are all 6 microns.

Test Example 1: Low grazing angle X-ray diffraction analysis (grazing incidenceX-ray diffraction, GIXRD)

In this test example, the electrolytic copper foils of the aforementioned Examples 1 to 12 and Comparative Examples 1 to 5 are used as samples to be tested, and an X-ray diffraction analyzer is used to conduct a low grazing angle X-ray diffraction experiment to obtain the first surface of the samples to be tested. And the characteristic peak signal intensity I ₁ of the (111) crystal plane of the second surface, the characteristic peak signal intensity I ₂ of the (200) crystal plane, the characteristic peak signal intensity I 3 of the (220) crystal plane, and the characteristic peak signal intensity I ₃ of the (111) crystal plane The characteristic peak half-maximum width W ₁ and the characteristic peak half-maximum width W ₂ of the (200) crystal plane.

The aforementioned parameters were calculated to obtain (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) and (W ₁ + W ₂ ) and the second surface (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ), (W ₁ +W ₂ ), the results are shown in Table 2 and Table 3.

Here, the parameters of the low grazing angle X-ray diffraction experiment are as follows:

I. Measuring instrument: X-ray diffraction analyzer: Bruker D8 ADVANCE Eco.

II.Measurement conditions: Incident light angle: 0.8°.

Test Example 2: Yield Strength

In this test example, the electrolytic copper foils of the aforementioned Examples 1 to 12 and Comparative Examples 1 to 5 are used as samples to be tested. Each sample to be tested is analyzed according to the IPC-TM-650 2.4.4.18 standard method to obtain an X-axis strain (ε ), the Y-axis is the stress-strain curve of stress (σ), draw a straight line parallel to the Y-axis when the strain is 0.5%, the intersection point of the measured curve of the sample to be tested and the straight line is is the yield strength, and the results are shown in Table 3.

Here, the instruments and measurement conditions selected to measure the yield strength of electrolytic copper foil are as follows:

I. Measuring instrument: AG-I universal tensile machine, purchased from Shimadzu Corp.

II. Measurement conditions: Sample size: length approximately 100 mm, width approximately 12.7 mm; chuck distance: 50 mm; and Crosshead speed: 50mm/min.

Test example 3: root mean square height (root mean square height, Sq)

In this test example, the electrolytic copper foils of the aforementioned Examples 1 to 12 and Comparative Examples 1 to 5 are used as samples to be tested, and the mean squares of the first surface and the second surface of each sample to be tested are measured according to the ISO 25178-2:2012 standard method. Root height (Sq), the results are shown in Table 3.

Here, the instruments and measurement conditions selected to measure the Sq of electrolytic copper foil are as follows:

I. Measuring instrument: Laser scanning conjugate focus microscope: LEXT OLS5000-SAF, purchased from Olympus Company; Objective lens: MPLAPON-100xLEXT.

II. Measurement conditions: Light source wavelength: 405 nanometers; Objective lens magnification: 100 times; Optical zoom: 1.0 times; Observation area: 129 microns × 129 microns; Resolution: 1024 pixels × 1024 pixels; Mode: Remove automatic tilt ( auto tilt removal); filter: no filter; temperature: 24±3℃; and relative humidity: 63±3%.

Test Example 4: Corrosion Resistance

In this test example, the electrolytic copper foils of the aforementioned Examples 1 to 12 and Comparative Examples 1 to 5 are used as the samples to be tested. The aforementioned samples to be tested are cut into test pieces of 10 cm × 10 cm, and the test pieces are soaked in 60 The test piece should be immersed in the lithium electrolyte of the lithium-ion battery at ℃ for up to 24 hours, then take out the test piece, dry the liquid on the test piece in an oven at 60°C, and visually confirm whether the appearance of the test piece changes color. The lithium electrolyte is 1 molar concentration The solution of degree (M), the solute is lithium hexafluorophosphate, and the solvent is a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1. If the test piece has local discoloration, it is judged as "×", which means that the electrolytic copper foil has poor corrosion resistance to the electrolyte; conversely, if there is no discoloration anywhere on the whole test piece, it is judged as "O", which means that the electrolytic copper foil has poor corrosion resistance to the electrolyte. The electrolyte has good corrosion resistance. The evaluation results are shown in Table 2 and Table 3.

"Electrode"

Examples 1A to 12A, Comparative Examples 1A to 5A

The first surface and the second surface of the electrolytic copper foils of the aforementioned Examples 1 to 12 and Comparative Examples 1 to 5 can be respectively coated with negative electrode slurries containing negative electrode active materials to form negative electrodes for lithium ion batteries. Specifically, the negative electrode can be generally produced through the steps described below.

First, prepare the negative electrode slurry, the composition of which is as follows: Mesophase graphitic carbon microspheres (MGP): 93.9 parts by weight, as the negative electrode active material; Conductive carbon black (Super P): 1 part by weight, as the conductive additive; Polypropylene Vinyl difluoride (PVDF 6020): 5 parts by weight, as solvent binder; oxalic acid: 0.1 parts by weight; and N -methylpyrrolidone (NMP): 60 parts by weight.

Next, the aforementioned negative electrode slurry is coated on the first surface and the second surface of the electrolytic copper foil respectively. The coating thickness of the negative electrode slurry is about 200 microns each, and dried in an oven at a temperature of 160° C. to achieve implementation. The negative electrodes of Examples 1A to 12A and Comparative Examples 1A and 5A.

Here, the coating conditions and rolling conditions set when making the negative electrode are as follows:

I. Coating conditions: coating rate: 5 meters/minute; and coating thickness: about 200 microns on each side.

II.Rolling conditions: Rolling speed: 1 meter/minute; Rolling pressure: 3000 pounds/square inch (psi); Roller size of rolling machine: 250 mm (outer diameter, φ) × 250 mm (width); Roller hardness: 62 to 65HRC; and roller material: high carbon chromium bearing steel (SUJ2).

Test Example 5: Coating Quality

In order to evaluate whether the electrolytic copper foil can have good active material coating quality when used to make negative electrodes, this test example uses the negative electrodes prepared in the above-mentioned Examples 1A to 12A and Comparative Examples 1A to 5A as samples to be tested, and visually inspects the samples. Observe whether there are wrinkles or wrinkles on both sides of the sample to be tested. If wrinkles or wrinkles appear on one side of the sample to be tested, the evaluation is "Δ", indicating that the coating quality of the sample to be tested is poor; if there are no wrinkles or wrinkles on both sides of the sample to be tested, the evaluation is "O" indicates that the sample to be tested can have the desired coating quality. The results are shown in Table 3.

"Lithium-ion Battery"

Examples 1A to 12A and Comparative Examples 1A to 5A were matched with the same type of positive electrode to prepare lithium ion batteries of Examples 1B to 12B and Comparative Examples 1B to 5B. For the convenience of explanation, the manufacturing process of lithium-ion batteries using the aforementioned negative electrode is described below.

First, prepare a cathode slurry with the following composition: lithium cobalt oxide (LiCoO ₂ ): 89 parts by weight, as the cathode active material; flake graphite (KS6): 5 parts by weight, as a conductive additive; conductive carbon black ( Super P): 1 part by weight, as a conductive additive; polyvinylidene fluoride (PVDF 1300): 5 parts by weight, as a solvent binder; N -methylpyrrolidone (NMP): 195 parts by weight.

Next, the positive electrode slurry is coated on both surfaces of the aluminum foil. After the solvent evaporates, the aforementioned positive electrode and the negative electrodes of each embodiment and each comparative example are cut to specific sizes, and then the positive electrode and the negative electrode are cut. Microporous isolation membranes (model: Celgard 2400, manufactured by Celgard Company) are sandwiched between the poles, which are alternately pushed and placed in a pressing mold filled with electrolyte (model: LBC322-01H, purchased from Xinzhoubang Technology Co., Ltd. ), sealed to obtain a laminated lithium-ion battery (size 41 mm × 34 mm × 53 mm).

Test Example 6: Capacity

In this test example, the lithium-ion batteries of Examples 1B to 12B and Comparative Examples 1B and 5B are used as samples to be tested. Under the following test conditions, the capacitance of the fifth charge and discharge cycle is recorded and the capacitance of each sample to be tested is compared. , the results are shown in Table 3.

Here, the conditions for each charge and discharge cycle test are as follows: charging mode: constant current-constant voltage (CCCV); discharge mode: constant current (CC); charging voltage: 4.2 volts (V); charging current: 0.2C; discharge Voltage: 2.8V: Discharge current: 0.2C; and measurement temperature: about 55℃.

"Discussion of Experimental Results"

The test results of the above-mentioned Test Examples 1 to 6 are summarized in Table 2 and Table 3 below.

As shown in Table 2 below, the first and second surfaces of the electrolytic copper foils of Examples 1 to 12 can have a ratio of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) of more than 0.83 according to GIXRD analysis. ) value and the value of (W ₁ + W ₂ ) below 0.80°, so the electrolytic copper foil can effectively resist the erosion of the electrolyte in lithium ion batteries, that is, it has good corrosion resistance to the electrolyte.

Looking back at the electrolytic copper foils of Comparative Examples 1 to 5, the first surface and the second surface of the electrolytic copper foil cannot simultaneously satisfy the value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) of 0.83 or above. , the value of (W ₁ + W ₂ ) is less than 0.80°. Therefore, the electrolytic copper foils of Comparative Examples 1 to 5 cannot have the required corrosion resistance to the electrolyte, so they are not suitable for application in lithium ion batteries.

Further detailed study of the test results of the electrolytic copper foils of Comparative Examples 1 to 5 shows that the value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I _{3 ) of the first surface of the electrolytic copper foils of Comparative Examples 1 and 4} is less than 0.83, and the value of (W ₁ + W ₂ ) is greater than 0.80°, so the electrolytic copper foil cannot have good corrosion resistance; although the first surface of the electrolytic copper foil in Comparative Example 2 has a value of (I ₁ + I ₂ )/(I ₁ +I ₂ +I ₃ ), but the value of (W ₁ +W ₂ ) is greater than 0.80°, so the electrolytic copper foil cannot have good corrosion resistance; and Comparative Example 3 and Although the first surface of the electrolytic copper foil of 5 has a value of (W ₁ +W ₂ ) below 0.80°, the value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) is less than 0.83 , so the electrolytic copper foil still cannot have good corrosion resistance. It can be seen that the first surface and the second surface of the electrolytic copper foil should have both the appropriate value of (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) and the appropriate (W ₁ +W ₂ ) value to ensure that the electrolytic copper foil has good corrosion resistance to the electrolyte.

In addition, the results of GIXRD analysis and Sq of the combined electrolytic copper foil can be seen. As shown in Table 3 below, the first and second surfaces of the electrolytic copper foils of Examples 1 to 10 have both (I ₁ +I In addition to the value of ₂ )/(I ₁ +I ₂ +I ₃ ) and the value of (W ₁ +W ₂ ) below 0.80°, the first surface of the electrolytic copper foil of Examples 1 to 10 further has an appropriate Sq( 0.20 microns to 0.55 microns), so the electrolytic copper foil not only has good corrosion resistance to the electrolyte, but also has good coating quality after being coated with active materials. The prepared Example 1B Lithium-ion batteries up to 10B have the characteristics of high electric capacity. Specifically, the capacity of the lithium-ion batteries of Examples 1B to 10B in the fifth charge-discharge cycle is greater than 300 mAh/g.

Looking back at the electrolytic copper foils of Examples 11 to 12 and Comparative Examples 3 to 4, since the Sq of the first surface of the electrolytic copper foil does not fall within the appropriate range, the electrolytic copper foils of Examples 11 to 12 and Comparative Examples 3 to 4 The foil cannot have good coating quality after being coated with the active material; on the other hand, the capacity of the lithium-ion batteries of Examples 11B to 12B and Comparative Examples 3B to 4B is less than 300mAh in the fifth charge-discharge cycle. /g, which is significantly lower than the capacity of the lithium-ion batteries of Embodiments 1B to 10B, and is less suitable for application to back-end products with high capacity requirements.

In summary, the present disclosure controls the characteristic peak signal intensity I ₁ of the (111) crystal plane of the first surface and the second surface of the electrolytic copper foil, and the characteristic peak signal intensity I ₂ of the (200) crystal plane. ) The characteristic peak signal intensity I ₃ of the crystal plane, the characteristic peak half-maximum width W ₁ of the (111) crystal plane, and the characteristic peak half-maximum width W ₂ of the (200) crystal plane can specifically improve the corrosion resistance of the electrolytic copper foil to the electrolyte. properties, thereby increasing the safety of its application in lithium-ion batteries.

In addition, according to different needs, the present disclosure can further control the Sq of the first surface of the electrolytic copper foil, so that the electrolytic copper foil can still have good coating quality after being coated with active materials, and further increase the capacity of the lithium-ion battery.

60:Electrolytic copper foil

61: Copper layer

611: Deposition surface

612:Roller surface

62: First anti-rust layer

621: First surface

63: Second anti-rust layer

631: Second surface

Claims (10)

An electrolytic copper foil having a first surface and a second surface located on opposite sides. The first surface and the second surface are analyzed by low grazing angle X-ray diffraction (GIXRD). The first surface and the second surface are each It has the characteristic peak signal intensity I ₁ of the (111) crystal plane, the characteristic peak signal intensity I ₂ of the (200) crystal plane, the characteristic peak signal intensity I ₃ of the (220) crystal plane, and the characteristic peak half-height of the (111) crystal plane. The width W ₁ and the characteristic peak half-maximum width W ₂ of the (200) crystal plane; wherein, the first surface and the second surface both meet the following conditions: (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) is 0.83 or more, and (W ₁ +W ₂ ) is 0.80° or less. The electrolytic copper foil as claimed in claim 1, wherein the yield strength of the electrolytic copper foil is greater than 230 MPa. The electrolytic copper foil as described in claim 1, wherein the first surface and the second surface both meet the following conditions: (I ₁ +I ₂ )/(I ₁ +I ₂ +I ₃ ) value is 0.84 to 1.00. The electrolytic copper foil as described in claim 1, wherein the first surface and the second surface both meet the following conditions: (W ₁ + W ₂ ) has a value of 0.25° to 0.75°. The electrolytic copper foil according to claim 1, wherein the yield strength of the electrolytic copper foil is 231MPa to 300MPa. The electrolytic copper foil according to any one of claims 1 to 5, wherein the root mean square height (Sq) of the first surface is 0.20 microns to 0.55 microns. The electrolytic copper foil according to claim 6, wherein Sq of the second surface is 0.20 micron to 0.55 micron. The electrolytic copper foil according to claim 7, wherein the absolute difference between Sq of the first surface and Sq of the second surface is less than 0.15 micron. An electrode for a lithium-ion battery, which includes the electrolytic copper foil described in any one of claims 1 to 8. A lithium-ion battery comprising the electrode described in claim 9.

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