A copper electrode foil for lithium batteries and its preparation method

Abstract

This invention provides an electrode copper foil for lithium batteries and its preparation method. The electrode copper foil includes a substrate layer, with oxygen-free copper layers respectively disposed on the upper and lower surfaces of the substrate layer, and an anti-oxidation conductive layer disposed on the outer surface of each oxygen-free copper layer. In this invention, a layered electrode copper foil structure is prepared by combining coating and magnetron sputtering methods, resulting in good thickness uniformity and a thinner thickness; the substrate layer in the layered structure makes the overall weight lighter; and the anti-oxidation conductive layer in the layered structure makes the whole structure less susceptible to oxidation.

Description

Technical Field

[0001] This invention relates to the field of electrode copper foil technology, and in particular to an electrode copper foil for lithium batteries and a method for preparing the same. Background Technology

[0002] Currently, the electrode copper foil used in lithium batteries in existing technologies is usually made of two types: copper ingot rolled copper foil and electrolytic copper foil. The production equipment and processes for copper ingot rolled copper foil and electrolytic copper foil are complex, and the pure copper foil produced is heavy, has poor thickness uniformity, and is easy to oxidize. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to provide an electrode copper foil for lithium batteries and a method for preparing the same, wherein the electrode copper foil is lightweight, has uniform thickness, and is not easily oxidized.

[0004] In a first aspect, the present invention provides an electrode copper foil for lithium batteries, comprising a substrate layer, wherein an oxygen-free copper layer is respectively disposed on the upper and lower surfaces of the substrate layer, and an anti-oxidation conductive layer is disposed on the outer surface of each oxygen-free copper layer.

[0005] Furthermore, the substrate layer is made of polyesterimide film with a thickness of 1µm to 12µm.

[0006] Furthermore, the oxygen-free copper layer is made of pure copper and has a thickness of 100nm to 3000nm.

[0007] Furthermore, the antioxidant conductive layer is made of one or more of titanium, nickel, niobium and ITO, or a mixture of at least two, with a thickness of 5nm to 200nm.

[0008] Secondly, the present invention also provides a method for preparing electrode copper foil for lithium batteries, characterized in that the preparation method includes the following steps:

[0009] Step S10: A peelable first polyurethane protective film is coated onto one surface of the substrate layer by a coating method.

[0010] Step S11: On the other surface of the substrate layer, an oxygen-free copper layer and an anti-oxidation conductive layer are sequentially sputtered by multi-target magnetron sputtering.

[0011] Step S12: On the outer surface of the antioxidant conductive layer, a peelable second polyurethane protective film is coated and laminated.

[0012] Step S13: Peel off the first polyurethane protective film by coating and peeling method so that the substrate layer forms a peeling surface;

[0013] Step S14: On the stripped surface of the substrate layer, another oxygen-free copper layer and an anti-oxidation conductive layer are sequentially sputtered by magnetron sputtering.

[0014] Step S15: The second polyurethane protective film is peeled off by coating and peeling method to form electrode copper foil.

[0015] Furthermore, in step S10, the coating and winding tension is 300 N / M to 100 N / M, and the coating and winding speed is 1 m / min to 35 m / min.

[0016] Further, in step S11, the magnetron sputtering chamber contains 600-800 smcc of argon gas, the temperature is -15-20℃, the vacuum degree is 3.0E-0.003 Torr, and the magnetron sputtering power is 5-50KW;

[0017] During the magnetron sputtering process, the winding is carried out by a winding method with a winding speed of 1m / min to 20m / min and a winding tension of 300N / M to 100N / M.

[0018] Ten planar cathode targets were used when sputtering oxygen-free copper layers.

[0019] When sputtering the antioxidant conductive layer, a single planar cathode target is used.

[0020] Furthermore, in step S13, the peel force of the bonding surface of the first polyurethane protective film is 25gf to 75gf.

[0021] Furthermore, in step S15, the sheet resistance of the electrode copper foil surface is ≤50 ohms / □.

[0022] Furthermore, the thickness of the substrate layer is 6 μm, the thickness of the oxygen-free copper layer is 1000 nm, the thickness of the anti-oxidation conductive layer is 28 nm, and the thickness of both the first polyurethane protective film and the second polyurethane protective film is 23 μm.

[0023] Compared with the prior art, the present invention uses a combination of coating and magnetron sputtering to prepare layered electrode copper foil, which results in good thickness uniformity and thinness; the substrate layer in the layered structure makes the overall weight lighter; and the anti-oxidation conductive layer in the layered structure makes the whole structure less susceptible to oxidation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the copper electrode foil used in lithium batteries in this invention.

[0025] Explanation of key component symbols:

[0026] Substrate layer 10 oxygen-free copper layer 11 Antioxidant conductive layer 12

[0027] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0029] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] Example 1

[0032] Firstly, the problem of wrinkling during magnetron sputtering and winding of 6-micron polyester imide films is solved by coating and lamination. Existing processes cannot effectively magnetron sputtered and wind up 6-micron polyester imide films. This process first laminates a 25g peel strength PET protective film on one side of the 6-micron polyester imide film. The lamination speed is 20 meters per minute, the lamination and winding tension is 150 N / M, the lamination pressure is 4 kg, and the thickness of the PET protective film is 23 microns. Through lamination, a substrate with a thickness of 29 microns is obtained. This process increases the thickness of the substrate required for magnetron sputtering to solve the problem of the inability to effectively magnetron sputtered and wind up 6-micron polyester imide films.

[0033] On the other side of the polyurethane substrate layer coated with a protective film, a film is sputtered onto the substrate surface using a roll-to-roll magnetron sputtering method. The speed of the roll-to-roll magnetron sputtering equipment is set to 15 meters per minute, the winding tension is controlled at 150 N / m, and the sputtering vacuum degree is below 3.0E-0.003 Torr. Preferably, the temperature of the chamber is maintained between -15 and 20°C during magnetron sputtering. The corresponding target working chamber is filled with 750 smcc of argon gas. The sputtering power of 10 oxygen-free copper planar cathode targets is 26 kW, and the sputtering power of 1 titanium planar target is 15 kW. The sputtering thickness of oxygen-free copper is 1000 nm, and the sputtering thickness of titanium is 25 nm, thereby obtaining a stable first conductive copper foil surface with a sheet resistance of ≤50 ohms / □.

[0034] The second PET protective film is coated onto the first conductive copper foil surface by a coating and lamination method. The coating speed is 20 meters per minute, the coating winding tension is 150 N / M, the coating pressure is 4 KG, and the thickness of the PET protective film is 23 micrometers. During the coating process, the first PET protective film is simultaneously peeled off. The purpose of this process is to increase the thickness of the substrate that needs to be coated by magnetron sputtering, and to solve the problem that the 6-micrometer substrate cannot be effectively coated and wound up by magnetron sputtering.

[0035] Sputtering is performed on the polyesterimide film after the first protective film has been peeled off using magnetron sputtering. The speed of the magnetron sputtering equipment is set to 15 m / min, the winding tension is controlled at 150 N / m, and the sputtering vacuum degree is below 3.0E-0.003 Torr. Preferably, the temperature of the chamber is maintained between -15 and 20°C during magnetron sputtering. The corresponding target working chamber is filled with 750 smcc of argon gas. The sputtering power of 10 oxygen-free copper planar cathode targets is 26 kW, and the sputtering power of 1 titanium planar target is 15 kW. The sputtering thickness of oxygen-free copper is 1000 nm, and the sputtering thickness of titanium is 25 nm, thereby obtaining a stable second conductive copper foil surface with a sheet resistance of ≤50 ohms / □.

[0036] The protective film covering the first conductive copper foil is peeled off and wound up using a coating peeling method. The coating speed is 20 meters per minute, the coating and winding tension is 150 N / m, the coating pressure is 4 kg, and the thickness of the PET protective film is 23 micrometers, thus realizing the production of double-sided conductive copper foil.

[0037] Example 2

[0038] Firstly, the problem of wrinkling during magnetron sputtering and winding of 6-micron polyester imide films is solved by coating and lamination. Existing processes cannot effectively magnetron sputtered and wind up 6-micron polyester imide films. This process first laminates a 30g peel strength PET protective film on one side of the 6-micron polyester imide film. The lamination speed is 20 meters per minute, the lamination and winding tension is 200 N / m, the lamination pressure is 4 kg, and the thickness of the PET protective film is 23 microns. Through lamination, a substrate with a thickness of 29 microns is obtained. This process increases the thickness of the substrate required for magnetron sputtering to solve the problem of the inability to effectively magnetron sputtered and wind up 6-micron polyester imide films.

[0039] On the other side of the polyurethane substrate layer coated with a protective film, a film is sputtered onto the substrate surface using a roll-to-roll magnetron sputtering method. The speed of the roll-to-roll magnetron sputtering equipment is set to 18 meters per minute, the winding tension is controlled at 150 N / m, and the sputtering vacuum degree is below 3.0E-0.003 Torr. Preferably, the temperature of the chamber is maintained between -15 and 20°C during magnetron sputtering. The target working chamber is filled with 700 smcc of argon gas, and the ITO planar target chamber is filled with 15 smcc of oxygen gas. The sputtering power of 10 oxygen-free copper planar cathode targets is 29 kW, and the sputtering power of 1 ITO planar target is 11 kW. The sputtering thickness of oxygen-free copper is 1100 nm, and the sputtering thickness of ITO is 28 nm, thereby obtaining a stable conductive copper film with a sheet resistance of ≤50 ohms / □.

[0040] A second PET protective film is coated onto the plated copper foil using a coating and lamination method. The coating speed is 20 meters per minute, the coating winding tension is 150 N / m, the coating pressure is 4 kg, and the thickness of the PET protective film is 23 micrometers. During the coating process, the first PET protective film is simultaneously peeled off. The purpose of this process is to increase the thickness of the substrate that needs to be coated by magnetron sputtering, and to solve the problem that 6-micrometer substrates cannot be effectively coated and wound up by magnetron sputtering.

[0041] Sputtering is performed on the polyesterimide film after the first protective layer has been peeled off using magnetron sputtering. The speed of the magnetron sputtering equipment is set to 18 m / min, the winding tension is controlled at 150 N / m, and the sputtering vacuum degree is below 3.0E-0.003 Torr. Preferably, the temperature of the chamber is maintained between -15 and 20°C during magnetron sputtering. The target working chamber is filled with 700 smcc of argon gas, the ITO planar target chamber is filled with 15 smcc of oxygen gas, the sputtering power of 10 oxygen-free copper planar cathode targets is 29 kW, the sputtering power of 1 nickel planar target is 11 kW, the sputtering thickness of oxygen-free copper is 1100 nm, and the sputtering thickness of titanium is 28 nm, thereby obtaining a stable second conductive copper foil surface with a sheet resistance of ≤50 ohms / □.

[0042] The protective film covering the first conductive copper foil is peeled off and wound up using a coating peeling method. The coating speed is 20 meters per minute, the coating and winding tension is 150 N / m, the coating pressure is 4 kg, and the thickness of the PET protective film is 23 micrometers, thus realizing the production of double-sided conductive copper foil.

[0043] Table 1 Oxidation Experiment of Copper Foil

[0044]

[0045]

[0046] As shown in Table 1, in this invention, the layered electrode copper foil is prepared by combining coating and magnetron sputtering (nanoscale process), which results in good thickness uniformity, thinness, and low sheet resistance. The substrate layer in the layered structure makes the overall weight lighter. The anti-oxidation conductive layer in the layered structure makes the whole structure less susceptible to oxidation.

[0047] In this specification, the various embodiments are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Furthermore, the above-described embodiments merely illustrate several implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. An electrode copper foil for lithium batteries, characterized in that: The material includes a substrate layer, on the upper and lower surfaces of which oxygen-free copper layers are respectively provided, and on the outer surface of each oxygen-free copper layer is an anti-oxidation conductive layer. The oxygen-free copper layer is made of pure copper and has a thickness of 100nm to 3000nm. The anti-oxidation conductive layer is made of one of titanium, nickel, niobium and ITO, or a mixture of at least two of them, and has a thickness of 5nm to 200nm. The method for preparing the electrode copper foil for lithium batteries includes the following steps: Step S10: A peelable first polyurethane protective film is coated onto one surface of the substrate layer by a coating method. Step S11: On the other surface of the substrate layer, an oxygen-free copper layer and an anti-oxidation conductive layer are sequentially sputtered by magnetron sputtering. Step S12: On the outer surface of the antioxidant conductive layer, a peelable second polyurethane protective film is coated and laminated. Step S13: Peel off the first polyurethane protective film by coating and peeling method so that the substrate layer forms a peeling surface; Step S14: On the stripped surface of the substrate layer, another oxygen-free copper layer and an anti-oxidation conductive layer are sequentially sputtered by magnetron sputtering. Step S15: The second polyurethane protective film is peeled off by coating and peeling method to form electrode copper foil.

2. The electrode copper foil for lithium batteries according to claim 1, characterized in that, The substrate layer is made of polyesterimide film with a thickness of 1µm to 12µm.

3. The electrode copper foil for lithium batteries according to claim 1, characterized in that, In step S10, the coating and winding tension is 300 N / M to 100 N / M, and the coating and winding speed is 1 m / min to 35 m / min.

4. The electrode copper foil for lithium batteries according to claim 1, characterized in that, In step S11, the magnetron sputtering chamber contains 600-800 smcc of argon gas, the temperature is -15-20℃, the vacuum degree is 3.0E-0.003 Torr, and the magnetron sputtering power is 5-50KW. During magnetron sputtering, the winding process is carried out by a winding method with a winding speed of 1m / min to 20m / min and a winding tension of 300N / M to 100N / M. Ten planar cathode targets were used when sputtering oxygen-free copper layers. When sputtering the antioxidant conductive layer, a single planar cathode target is used.

5. The electrode copper foil for lithium batteries according to claim 1, characterized in that, In step S13, the peel force of the bonding surface of the first polyurethane protective film is 25gf to 75gf.

6. The electrode copper foil for lithium batteries according to claim 1, characterized in that, In step S15, the sheet resistance of the electrode copper foil surface is ≤50 ohms / □.

7. The electrode copper foil for lithium batteries according to claim 1, characterized in that, The substrate layer has a thickness of 6 μm, the oxygen-free copper layer has a thickness of 1000 nm, the antioxidant conductive layer has a thickness of 28 nm, and the first and second polyurethane protective films both have a thickness of 23 μm.

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