Method for manufacturing lithium battery negative electrodes

Abstract

PURPOSE: To provide a manufacturing method of a negative electrode of a lithium battery.SOLUTION: A manufacturing method of a lithium battery negative electrode, includes at least the following steps of providing an electric plating device, in which the electric plating device includes a dry chamber, and the dry chamber contains an electric plating tank, an electric plating wheel set, and a film adhesion wheel set. A copper foil is arranged to the dry chamber. The manufacturing method of a lithium battery negative electrode, includes the steps of: transporting the copper foil by the electric plating wheel set; forming a lithium metal layer onto the copper film; and forming a copper-lithium complex metal layer by the copper foil and the lithium metal layer. The film adhesion wheel set transports the copper-lithium complex metal layer, and a protection film is adhered to the copper-lithium complex metal layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a negative electrode for a lithium battery. [Background technology]

[0002] Lithium metal is the primary material in the negative electrode of lithium batteries. Summary of the Invention [Problem to be solved by the invention]

[0003] However, due to its high activity, lithium metal is easily reacted with water, oxygen, etc., and is oxidized and loses its activity, which affects the performance of lithium batteries. Therefore, how to improve the negative electrode of lithium batteries has become a key factor in the future development of lithium batteries. [Means for solving the problem]

[0004] The present invention provides a method for manufacturing a negative electrode for a lithium battery, and the composite negative electrode structure produced by this method can effectively improve the performance of the lithium battery and facilitate mass production.

[0005] The method for manufacturing a lithium battery negative electrode of the present invention includes at least the following steps: providing an electroplating apparatus having a drying chamber including an electroplating tank, an electroplating wheel set, and a film application wheel set; placing a copper foil in the drying chamber; transporting the copper foil through the electroplating wheel set to form a lithium metal layer on the copper foil, whereby the copper foil and the lithium metal layer form a copper-lithium composite metal layer; transporting the copper-lithium composite metal layer through the film application wheel set to apply a protective film to the copper-lithium composite metal layer;

[0006] In one embodiment of the present invention, the electroplating tank includes a first electrode, and the electroplating wheel set includes a first guide wheel and a second guide wheel disposed within the electroplating tank, and a first conductive wheel and a second conductive wheel disposed outside the electroplating tank. The first guide wheel and the second guide wheel are configured so that the copper foil in the electroplating tank is parallel to the first electrode. The first conductive wheel and the second conductive wheel are used as the second electrode.

[0007] In one embodiment of the present invention, the drying chamber further includes a copper foil supply device and a protective film supply device, the copper foil supply device is connected to the electroplating wheel set, and the protective film supply device is connected to the film application wheel set.

[0008] In one embodiment of the present invention, the material of the protective film includes a polyimide film, a polyester film, or a water and gas barrier film.

[0009] In one embodiment of the present invention, the drying chamber further includes a drying device, and the drying device is configured to remove the organic solvent on the copper-lithium composite metal layer.

[0010] In one embodiment of the invention, the drying device comprises an air knife, a roller, an infrared heater, or a combination thereof.

[0011] In one embodiment of the present invention, the environment of the drying chamber is formed by an inert gas.

[0012] In one embodiment of the present invention, the protective film at least completely covers the surface of the lithium metal layer.

[0013] In one embodiment of the present invention, the protective film is in direct contact with the lithium metal layer and the copper foil.

[0014] In one embodiment of the present invention, the electroplating solution in the electroplating tank comprises a lithium salt and an organic solvent, the lithium salt being Lithium hexafluorophosphate , lithium boron hexafluoride, lithium bis(trifluoromethanesulfonyl)imide, or a combination thereof, and the organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, glycol dimethyl ether, dimethyl ether, or a combination thereof. [Effects of the Invention]

[0015] As described above, the negative electrode of the lithium battery of the present invention is manufactured in a drying chamber. An electroplating wheel set in the drying chamber continuously deposits lithium metal on a copper foil in an electroplating tank to form a copper-lithium composite metal layer. A film attachment wheel set in the drying chamber continuously attaches a protective film to the copper-lithium composite metal layer withdrawn from the electroplating tank. In this way, the low-reactivity copper foil and protective film can effectively reduce the probability of lithium metal oxidation, and the resulting composite negative electrode structure can effectively improve the performance of lithium batteries and facilitate mass production.

[0016] In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following detailed description of the embodiments is given with reference to the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a flowchart of a method for manufacturing a lithium battery negative electrode according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram of an electroplating apparatus according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view of a lithium battery negative electrode according to one embodiment of the present invention. [Figure 4] FIG. 2 is a schematic cross-sectional view of a lithium battery negative electrode according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the following detailed description, for purposes of explanation and not limitation, exemplary embodiments disclosing specific details are set forth in order to provide a thorough understanding of various principles of the present invention. However, it will be apparent to those skilled in the art having the benefit of this invention that the present invention may be practiced in other embodiments that deviate from the specific details disclosed herein. Moreover, descriptions of well-known devices, methods, and materials may be omitted so as not to obscure the description of various principles of the present invention.

[0019] Here, ranges expressed as "one value to another value" are a summary method for avoiding the need to list every single value in the range in the specification. Thus, the description of a particular numerical range includes any value within that range and smaller numerical ranges defined by any value within that range, and is the same as if that any value and smaller numerical range were explicitly stated in the specification.

[0020] Unless otherwise specified, the term "between" when used in this specification to define a range of values is intended to cover the range equal to and between the recited endpoints. For example, a size range between a first value and a second value means covering the first value, the second value, and any value between the first and second values.

[0021] In the present invention, non-limiting terms (e.g., may, can, for example, or other similar terms) refer to optional or selective implementation, inclusion, addition, or presence.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as common knowledge and understanding in the art to which this invention belongs. It is to be understood that terms (e.g., those defined in commonly used dictionaries) should be interpreted to have a meaning consistent with their meaning in the relevant technical context, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0023] FIG. 1 is a flowchart of a method for manufacturing a lithium battery negative electrode according to one embodiment of the present invention. The method for manufacturing a lithium battery negative electrode according to the present invention can include at least the following steps. Referring to FIG. 1, first, an electroplating apparatus is provided having a drying chamber including an electroplating tank, an electroplating wheel set, and a film application wheel set (step S100). Next, a copper foil is placed in the drying chamber (step S200). The electroplating wheel set transports the copper foil to form a lithium metal layer on the copper foil, and the copper foil and the lithium metal layer form a copper-lithium composite metal layer (step S300). Next, the film application wheel set transports the copper-lithium composite metal layer to apply a protective film to the copper-lithium composite metal layer (step S400). Thus, the lithium battery negative electrode according to the present invention can be manufactured in the drying chamber. Lithium metal can be continuously deposited on the copper foil in the electroplating tank via the electroplating wheel set in the drying chamber to form a copper-lithium composite metal layer. In addition, a protective film can be continuously attached to the copper-lithium composite metal layer drawn out from the electroplating tank via a film attachment wheel set in the drying chamber. In this way, the low-reactivity copper foil and protective film can effectively reduce the probability of lithium metal oxidation, so that the resulting composite negative electrode structure can effectively improve the performance of lithium batteries and facilitate mass production.

[0024] Figure 2 is a schematic diagram of an electroplating apparatus according to one embodiment of the present invention. Figure 3 is a schematic cross-sectional view of a lithium battery negative electrode according to one embodiment of the present invention. Figure 4 is a schematic cross-sectional view of a lithium battery negative electrode according to another embodiment of the present invention.

[0025] In one embodiment, the method for producing a lithium battery negative electrode can be produced using the electroplating apparatus 100 of Figure 2, but the present invention is not limited thereto. The electroplating apparatus can have other suitable devices and configurations not described herein without departing from the spirit and scope of the present invention.

[0026] 2 to 4, the electroplating apparatus 100 includes a drying chamber 110, which includes an electroplating tank 111, an electroplating wheel set 112, and a film application wheel set 113. In one embodiment, the dew point temperature of the drying chamber is, for example, lower than −40° C. The environment E of the drying chamber 110 is formed by an inert gas, which reduces the probability of lithium metal reacting with water, oxygen, etc. in the environment during the electroplating process, thereby further improving the production quality of lithium battery negative electrodes, but the present invention is not limited thereto. Here, the inert gas may be, for example, nitrogen, argon, or other suitable inert gases, or combinations thereof.

[0027] More specifically, the electroplating tank 111 includes a first electrode 111a, and the electroplating wheel set 112 includes a first guide wheel 112a and a second guide wheel 112b disposed within the electroplating tank 111, and a first conductive wheel 112c and a second conductive wheel 112d disposed outside the electroplating tank 111. The present invention does not limit the specific configurations of the first guide wheel 112a, the second guide wheel 112b, the first conductive wheel 112c, and the second conductive wheel 112d, and all configurations fall within the scope of the present invention as long as the first guide wheel 112a and the second guide wheel 112b are configured so that the copper foil in the electroplating tank 111 is arranged parallel to the first electrode 111a, and the first conductive wheel 112c and the second conductive wheel 112d are used as second electrodes (electrodes opposite to the first electrode 111a). Here, the material of the first guide wheel 112a and the second guide wheel 112b may be any suitable material that does not react with the electroplating solution, the material of the first electrode 111a includes lithium metal, stainless steel, etc., and the material of the first conductive wheel 112c and the second conductive wheel 112d includes titanium, stainless steel.

[0028] In this embodiment, the drying chamber 110 further includes a copper foil supply device 114 connected to the electroplating wheel set 112. Here, the copper foil 10 is, for example, a copper foil roll, and the copper foil supply device 114 may be in the form of a roller, thereby continuously feeding the copper foil roll to the electroplating wheel set 112 for the electroplating process. Also, as shown in FIG. 2, for example, the copper foil 10 first passes through a first conductive wheel 112c and is then drawn into the electroplating tank 111 by a first guide wheel 112a and a second guide wheel 112b. The first guide wheel 112a and the second guide wheel 112b then adjust the direction of the copper foil 10 so that the copper foil 10 is parallel to the first electrode 111a (FIG. 2 schematically shows the copper foil 10 as being parallel in the horizontal direction. However, in an embodiment not shown, the copper foil 10 may be parallel in the vertical direction). After lithium metal (the lithium metal layer in FIGS. 3 and 4) is deposited on the copper foil 10 by an electroplating process to form a copper-lithium composite metal layer, the copper foil 10 leaves the electroplating tank 111 and is drawn into the second conductive wheel 112d. Here, the thickness of the copper foil 10 may be between 6 microns and 35 microns, and the deposited lithium metal thickness may be between 0.5 microns and 20 microns, but the present invention is not limited thereto.

[0029] It should be noted that the electroplating solution in the electroplating tank 111 includes a lithium salt and an organic solvent, and the lithium salt is Lithium hexafluorophosphate , Lithium Boron Hexafluoride, Lithium Bis(trifluoromethanesulfonyl)imide, or a combination thereof; and the organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, ethylene glycol dimethyl ether, dimethyl ether, or a combination thereof. Specific details of the electroplating process will be understood by those skilled in the art and will not be repeated here.

[0030] The film application wheel set 113 includes a third guide wheel 113a connected to the second conductive wheel 112d and a press laminating wheel 113b connected to the third guide wheel 113a. The drying chamber 110 further includes a protective film device 115 connected to the film application wheel set 113. The protective film (see FIGS. 3 and 4) may be, for example, a polyimide (PI) film, a polyester (PET) film, or a water and gas barrier film. The protective film device 115 may be in the form of a roller, which continuously feeds the roll onto the press laminating wheel 113b to perform the film application process. The protective film (see FIGS. 3 and 4) may have any suitable thickness and is not limited by the present invention.

[0031] In one embodiment, the water and gas barrier film is, for example, an aluminum composite film roll (aluminum composite film) made of vapor-deposited aluminum on a non-stretch polypropylene film (CPP film), or a CPP film (for example, having a thickness of 6 microns to 35 microns) attached to an aluminum foil. Therefore, by utilizing the water and oxygen barrier properties of aluminum, lithium metal can be more effectively protected and stably prevented from oxidation with water or air in the environment. However, the present invention is not limited thereto, and other water and gas barrier films, for example, TAKELAC (trade name) by Mitsui Chemicals, can be used. TM A water and gas barrier film of "WPB-341" may be used. Here, the water and gas barrier film preferably has a water vapor transmission rate of 0.5 g / m 2 / day and oxygen permeability is 0.5cc / m 2 / day or less.

[0032] In one embodiment, as shown in FIG. 3 , the lithium metal layer 20 can completely cover the surface of the copper foil 10, so that the subsequent protective film 30 covering the lithium metal layer 20 does not need to be in direct contact with the copper foil 10. However, the present invention is not limited thereto. In another embodiment, as shown in FIG. 4 , the lithium metal layer 20 can partially cover the surface of the copper foil 10, leaving a portion of the surface of the copper foil 10 exposed. Therefore, the protective film 30 that is subsequently coated on the lithium metal layer 20 can be in direct contact with the lithium metal layer 20 and the copper foil 10. That is, the protective film 30 can at least completely cover the surface of the lithium metal layer 20 and selectively cover the surface of the copper foil 10.

[0033] In some embodiments, the drying chamber 110 further includes a drying device 116 configured to remove the organic solvent on the copper-lithium composite metal layer, and the drying device 116 includes an air knife, a roller, an infrared (IR) heater, or a combination thereof. For example, as shown in FIG. 2, the drying device 116 includes a first drying device 116a and a second drying device 116b, and the first drying device 116a Second guide wheel The second drying device 116 may be disposed between the first conductive wheel 112b and the second conductive wheel 112d, and the second drying device 116 may be disposed between the second conductive wheel 112d and the third conductive wheel 112d. Here, the drying devices 116 may be disposed on both sides of the copper-lithium composite metal layer simultaneously to dry the organic solvents on both sides simultaneously, but the present invention is not limited thereto.

[0034] In one embodiment, the drying chamber 110 further includes a winding device 117 connected to the film application wheel set 113, which winds and forms the composite negative electrode structure including the copper foil 10, the lithium metal layer 20, and the protective film 30. In this way, the processing speed of the subsequent lithium battery can be increased to meet the needs of mass production.

[0035] The following examples are provided to illustrate the effects of the present invention, but the patent scope of the present invention is not limited to the scope of the examples.

[0036] <Example>

[0037] First, a 6 μm to 8 μm copper foil and protective film (Takelac WPB-341 water and gas barrier film) for the negative electrode, an electrolyte:solvent:ethylene glycol dimethyl ether (DOL):dimethyl ether (DME) = 1:1, 1% to 5% 1M lithium salt (LiTFSI) and lithium nitrate (LiNO3) were prepared, and tensile leads were attached to the electroplating apparatus (100). The drying chamber was always maintained at a temperature below -40 °C with a water vapor dew point.

[0038] Step 2: The flow rate of nitrogen gas into the electroplating tank (111) was 50 cc / min.

[0039] Step 3: The electroplating production line was operated at a production rate of 0.1 m / min to 30 m / min, depending on the method for manufacturing lithium battery negative electrodes, until the length of each roll reached approximately 3,000 m to 10,000 m, i.e., until production stopped.

[0040] Step 4: Collect materials and extract the finished product, then repeat step 1 to continue production, achieving mass production.

[0041] As described above, the lithium battery anode of the present invention is manufactured in a drying chamber. An electroplating wheel set in the drying chamber continuously deposits lithium metal on a copper foil in an electroplating tank to form a copper-lithium composite metal layer. A film attachment wheel set in the drying chamber continuously attaches a protective film to the copper-lithium composite metal layer withdrawn from the electroplating tank. The low-reactivity copper foil and protective film effectively reduce the probability of lithium metal oxidation, resulting in a composite anode structure that effectively improves lithium battery performance and facilitates mass production.

[0042] While the present invention has been described with reference to the above-described embodiments, it will be apparent to those skilled in the art that modifications may be made to these embodiments without departing from the spirit of the invention, the scope of which is defined by the appended claims, not by the above detailed description. [Industrial Applicability]

[0043] The method for producing a lithium battery negative electrode of the present invention can be applied to the production of a lithium battery negative electrode. [Explanation of symbols]

[0044] 10 Copper foil 20 Lithium metal layer 30 Protective Film 100 Electroplating equipment 110 Drying room 111 Electroplating Tank 111a 1st electrode 112 Electroplated Wheel Set 112a First Guide 112b Second guide wheel 112c First conductive wheel 112d Second conductive wheel 113 Film-attached Wheel Set 113a Third guide wheel 113b Press Laminate Wheel 114 Copper foil supply device 115 Protective film device 116 Drying equipment 116a 1st drying device 116b 2nd drying device 117 Winding device

Claims

1. providing an electroplating apparatus having a drying chamber including an electroplating tank, an electroplating wheel set, and a film application wheel set; placing a copper foil in the drying chamber; conveying the copper foil through the electroplating wheel set to form a lithium metal layer on the copper foil, and the copper foil and the lithium metal layer form a copper-lithium composite metal layer; conveying the copper-lithium composite metal layer through the film application wheel set and applying a protective film to the copper-lithium composite metal layer; Including, The electroplating tank includes a first electrode, and the electroplating wheel set includes: a first guide wheel and a second guide wheel disposed in the electroplating tank and configured to cause the copper foil in the electroplating tank to be parallel to the first electrode; a first conductive wheel and a second conductive wheel disposed outside the electroplating tank and used as second electrodes; Including, the drying chamber further includes a drying device, the drying device being disposed between the second guide wheel and the second conductive wheel and configured to remove an organic solvent on the copper-lithium composite metal layer; The method for manufacturing a lithium battery negative electrode, wherein the protective film is in direct contact with the lithium metal layer and the copper foil.

2. 2. The method for manufacturing a lithium battery negative electrode according to claim 1, wherein the drying chamber further includes a copper foil supply device and a protective film supply device, the copper foil supply device being connected to the electroplating wheel set, and the protective film supply device being connected to the film laminating wheel set.

3. 2. The method for producing a lithium battery negative electrode according to claim 1, wherein the material of the protective film comprises a polyimide film, a polyester film, or a water and gas barrier film.

4. 2. The method for producing a lithium battery negative electrode according to claim 1, wherein the drying device comprises an air knife, a roller, an infrared heater, or a combination thereof.

5. 2. The method for producing a lithium battery negative electrode according to claim 1, wherein the environment of the drying chamber is formed by an inert gas.

6. 2. The method for producing a lithium battery negative electrode according to claim 1, wherein the protective film at least completely covers the surface of the lithium metal layer.

7. 2. The method for producing a lithium battery negative electrode according to claim 1, wherein the electroplating solution in the electroplating tank comprises a lithium salt and an organic solvent, the lithium salt comprising lithium hexafluorophosphate, lithium hexafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, or a combination thereof, and the organic solvent comprising ethylene carbonate, propylene carbonate, dimethyl carbonate, glycol dimethyl ether, dimethyl ether, or a combination thereof.

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