Manufacturing method of lithium battery negative electrode

Abstract

A method for manufacturing a lithium-ion battery negative electrode includes at least the following steps: An electroplating apparatus is provided, wherein the electroplating apparatus has a drying chamber, and the drying chamber includes an electroplating tank, an electroplating roller assembly, and a film-applying roller assembly. A copper foil is placed in the drying chamber. The electroplating roller assembly conveys the copper foil, causing a lithium metal layer to form on the copper foil, and the copper foil and the lithium metal layer constitute a copper-lithium composite metal layer. The film-applying roller assembly conveys the copper-lithium composite metal layer and applies a protective film to the copper-lithium composite metal layer.

Description

Method for manufacturing lithium battery negative electrode The present invention relates to a method for manufacturing a lithium battery negative electrode. Lithium metal is a key material for the negative electrode of lithium batteries. However, due to the high activity of lithium metal, it is easily oxidized and loses its activity by reacting with water, oxygen, etc. In this way, the performance of lithium batteries will be affected. Therefore, how to improve the lithium battery negative electrode is a key factor in the future development of lithium batteries. The present invention provides a method for manufacturing a lithium battery negative electrode, and the composite negative electrode structure manufactured by it can effectively improve the performance of lithium batteries and is conducive to mass production. A method for manufacturing a lithium battery negative electrode according to the present invention at least includes the following steps. Provide electroplating equipment, wherein the electroplating equipment has a drying chamber, and the drying chamber includes an electroplating tank, an electroplating wheel set and a film sticking wheel set. Place the copper foil in the drying chamber. 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. The film sticking wheel set transports the copper-lithium composite metal layer and attaches a protective film to the copper-lithium composite metal layer. In an embodiment of the present invention, the above 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 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 to make the copper foil in the electroplating tank parallel to the first electrode. The first conductive wheel and the second conductive wheel serve as the second electrode. In an embodiment of the present invention, the above drying chamber further includes a copper foil supply device and a protective film supply device, and the copper foil supply device is connected to the electroplating wheel set, and the protective film supply device is connected to the laminating wheel set. In an embodiment of the present invention, the material of the above protective film includes a polyimide film, a polyester film or a water and gas barrier film. In an embodiment of the present invention, the above 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. In an embodiment of the present invention, the above drying device includes an air knife, a roller, an infrared heater or a combination thereof. In an embodiment of the present invention, the environment of the above drying chamber is composed of an inert gas. In an embodiment of the present invention, the above protective film at least completely covers the surface of the lithium metal layer. In an embodiment of the present invention, the above protective film directly contacts the lithium metal layer and the copper foil. In an embodiment of the present invention, the electroplating solution in the above electroplating tank includes a lithium salt and an organic solvent, and the lithium salt includes lithium hexafluorophosphate, lithium hexafluoroborate, lithium bis(trifluoromethylsulfonyl)amide 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. Based on the above, the lithium battery negative electrode of the present invention is manufactured in a drying chamber, and through the electroplating wheel set in the drying chamber, lithium metal can be continuously deposited on the copper foil in the electroplating tank to form a copper-lithium composite metal layer. Also, through the film sticking wheel set in the drying chamber, the protective film can be continuously attached to the copper-lithium composite metal layer drawn out from the electroplating tank. In this way, the copper foil with low reactivity and the protective film can effectively reduce the probability of lithium metal being oxidized. Therefore, the manufactured composite negative electrode structure can effectively improve the performance of the lithium battery and is conducive to mass production. To make the above features and advantages of the present invention more obvious and understandable, the following specific embodiments are given, and detailed descriptions are provided in conjunction with the accompanying drawings as follows. In the following detailed description, for the purpose of illustration rather than limitation, exemplary embodiments revealing specific details are set forth to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to those of ordinary skill in the art that the present invention can be practiced in other embodiments without departing from the specific details disclosed herein. In addition, descriptions of well-known devices, methods, materials, and other specific details may be omitted to avoid obscuring the description of the various principles of the present invention. In this document, a range represented by "from one numerical value to another numerical value" is a summary representation method to avoid listing all the numerical values in the range one by one in the specification. Therefore, the description of a specific numerical range encompasses any numerical value within that numerical range and the smaller numerical ranges defined by any numerical value within that numerical range, as if the arbitrary numerical value and the smaller numerical range were written out explicitly in the specification. Unless otherwise specified, the term "between" used in this specification to define a numerical range is intended to cover the range equal to the endpoint values and the range between the endpoint values. For example, a dimension range between a first numerical value and a second numerical value means that the dimension range can cover the first numerical value, the second numerical value, and any numerical value between the first numerical value and the second numerical value. In this document, non-limiting terms (such as: may, can, for example, or other similar terms) are non-essential or optional implementations, inclusions, additions, or existences. Unless otherwise defined, all terms used herein (including technical terms and scientific terms) have the same meaning as those commonly understood by those having ordinary knowledge or ordinary understanding in the technical field to which the present invention pertains. It will also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the relevant technical background and should not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein. FIG. 1 is a flowchart of a method for manufacturing a lithium battery negative electrode according to an embodiment of the present invention. The method for manufacturing a lithium battery negative electrode of the present invention may at least include the following steps. Referring to FIG. 1, first, a plating apparatus is provided, wherein the plating apparatus has a drying chamber, and the drying chamber includes a plating bath, a plating wheel set, and a film sticking wheel set (step S100). Next, a copper foil is placed in the drying chamber (step S200), and the plating 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 constitute a copper-lithium composite metal layer (step S300). Then, the film sticking wheel set transports the copper-lithium composite metal layer and attaches a protective film to the copper-lithium composite metal layer (step S400). Accordingly, the lithium battery negative electrode of the present invention is manufactured in the drying chamber, and by means of the plating wheel set in the drying chamber, lithium metal can be continuously deposited on the copper foil in the plating bath to form a copper-lithium composite metal layer. Also, by means of the film sticking wheel set in the drying chamber, the protective film can be continuously attached to the copper-lithium composite metal layer drawn out from the plating bath. In this way, the copper foil with low reactivity and the protective film can effectively reduce the probability of lithium metal being oxidized. Therefore, the manufactured composite negative electrode structure can effectively improve the performance of the lithium battery and is conducive to mass production. FIG. 2 is a schematic diagram of a plating apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional schematic diagram of a lithium battery negative electrode according to an embodiment of the present invention. FIG. 4 is a cross-sectional schematic diagram of a lithium battery negative electrode according to another embodiment of the present invention. In one embodiment, the method for manufacturing a lithium battery negative electrode can be manufactured by the plating apparatus 100 of FIG. 2, but the present invention is not limited thereto. Without departing from the spirit and scope of the present invention, the plating apparatus may have other suitable devices and configurations not described herein. Referring to FIGS. 2 to 4, the plating apparatus 100 has a drying chamber 110, and the drying chamber 110 includes a plating bath 111, a plating wheel set 112, and a film sticking wheel set 113. In one embodiment, the dew point temperature of the drying chamber is, for example, less than -40°C, and the environment E of the drying chamber 110 is composed of an inert gas to reduce the probability of lithium metal reacting with water or oxygen in the environment during the plating process, and further improve the production quality of the lithium battery negative electrode, but the present invention is not limited thereto. Here, the inert gas is, for example, nitrogen, argon, or other suitable inert gases and their combinations. Furthermore, the electroplating bath 111 includes a first electrode 111a. The electroplating wheel set 112 includes a first guide wheel 112a and a second guide wheel 112b disposed in the electroplating bath 111, and a first conductive wheel 112c and a second conductive wheel 112d disposed outside the electroplating bath 111. The specific forms of the first guide wheel 112a, the second guide wheel 112b, the first conductive wheel 112c, and the second conductive wheel 112d are not limited in the present invention. As long as the first guide wheel 112a and the second guide wheel 112b can be configured to make the copper foil 10 in the electroplating bath 111 parallel to the first electrode 111a, and the first conductive wheel 112c and the second conductive wheel 112d can serve as the second electrode (the counter electrode of the first electrode 111a), they all fall within the protection scope of the present invention. The materials of the first guide wheel 112a and the second guide wheel 112b can be any suitable materials that do not react with the electroplating solution. The materials of the first electrode 111a include lithium metal, stainless steel, or the like, while the materials of the first conductive wheel 112c and the second conductive wheel 112d include titanium and stainless steel. In this embodiment, the drying chamber 110 further includes a copper foil supply device 114 connected to the electroplating wheel set 112. The copper foil 10 is, for example, a copper foil tape, and the copper foil device 114 can be in the form of rollers to continuously send the copper foil tape to the electroplating wheel set 112 for electroplating process. In addition, as shown in Figure 2, the copper foil 10, for example, first passes through the first conductive wheel 112c and is then牵引ed by the first guide wheel 112a and the second guide wheel 112b into the electroplating bath 111. The direction of the copper foil 10 is adjusted by the first guide wheel 112a and the second guide wheel 112b to make it parallel to the first electrode 111a (Figure 2 schematically shows parallel in the horizontal direction. However, in an embodiment not shown, it can also be parallel in the vertical direction). After the copper foil 10 undergoes an electroplating process to deposit lithium metal (such as the lithium metal layer 20 in Figures 3 and 4) on the copper foil 10 to form a copper-lithium alloy metal layer, it leaves the electroplating bath 111 and is牵引ed to the second conductive wheel 112d. Here, the thickness of the copper foil 10 can be between 6 microns and 35 microns, and the deposition thickness of lithium metal can be between 0.5 microns and 20 microns, but the present invention is not limited thereto. It should be noted that the electroplating solution in the electroplating bath 111 includes a lithium salt and an organic solvent. The lithium salt includes lithium hexafluorophosphate, lithium hexafluoroborate, bis(trifluoromethylsulfonyl)amine lithium, or a combination thereof. The organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, ethylene glycol dimethyl ether, dimethyl ether, or a combination thereof. The specific details of the electroplating process are understandable to those of ordinary skill in the relevant technical field and will not be elaborated herein. In addition, the film laminating wheel set 113 includes a third guide wheel 113a connected to the second conductive wheel 112d and a pressing and laminating wheel 113b connected to the third guide wheel 113a. The drying chamber 110 further includes a protective film device 115 connected to the laminating wheel set 113. The protective film (such as the protective film 30 in FIGS. 3 and 4) is, for example, a polyimide (PI) film, a polyester (PET) film, or a water and gas barrier film. The protective film device 115 can be in the form of a roller to continuously send the aforementioned tape to the pressing and laminating wheel 113b for the film laminating process. Here, the protective film (such as the protective film 30 in FIGS. 3 and 4) can have any suitable thickness, which is not limited in the present invention. In one embodiment, the aforementioned water and gas barrier film is, for example, an aluminum composite film tape (aluminum composite film) which is a cast polypropylene film (CPP film) vapor-deposited with aluminum, or a CPP film attached to an aluminum foil (the thickness is, for example, between 6 microns and 35 microns). By virtue of the water and oxygen barrier properties of aluminum, the lithium metal can be more effectively protected from stably reacting with water or air in the environment by oxidation. However, the present invention is not limited thereto, and it can also be other water and gas barrier films, such as the water and gas barrier film with the trade name Mitsui Chemicals TAKELAC™ WPB-341. Here, the water and gas barrier film preferably has a water vapor transmission rate of 0.5 g / m 2 / day and an oxygen transmission rate of 0.5 cc / m 2 / day or less. In one embodiment, as shown in FIG. 3, the lithium metal layer 20 can completely cover the surface of the copper foil 10. Therefore, the subsequent protective film 30 covering the lithium metal layer 20 may not directly contact 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, exposing a part of the surface of the copper foil 10. Therefore, the subsequent protective film 30 covering the lithium metal layer 20 can directly contact the lithium metal layer 20 and the copper foil 10, that is, the protective film 30 at least completely covers the surface of the lithium metal layer 20 and optionally covers the surface of the copper foil 10. In some embodiments, the drying chamber 110 further includes a drying device 116, and the drying device 116 is configured to remove the organic solvent on the copper-lithium composite metal layer. 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. The first drying device 116a can be disposed between the second guide wheel 112b and the second conductive wheel 112d, and the second drying device can be disposed between the second conductive wheel 112d and the third guide wheel 113a. The drying device 116 can be disposed on both sides of the copper-lithium composite metal layer at the same time to dry the organic solvents on both sides simultaneously. However, the present invention is not limited thereto. In one embodiment, the drying chamber 110 further includes a winding device 117 connected to the laminating wheel set 113 to wind and form the composite negative electrode structure including the copper foil 10, the lithium metal layer 20, and the protective film 30. In this way, the manufacturing speed of subsequent lithium batteries can be increased to meet the requirements of mass production. The following embodiments are listed to illustrate the effects of the present invention, but the scope of the rights of the present invention is not limited to the scope of the embodiments. <Examples> First, prepare a 6um - 8um copper foil for the negative electrode, a protective film (a water - and air - barrier film of TAKELAC™ WPB - 341), an electroplating solution: solvent: ethylene glycol dimethyl ether (DOL): dimethyl ether (DME)=1:1, 1M lithium salt (LiTFSI), and lithium nitrate LiNO 3 at 1 - 5%, and the traction lead wire is installed in the electroplating equipment (100), where the drying chamber always maintains a water vapor dew point of less than - 40°C. Step 2: The nitrogen flux into the electroplating tank body (111) is 50 cc / minute (min). Step 3: The electroplating operation line of the above - mentioned method for manufacturing the lithium - battery negative electrode is produced at a production speed of 0.1 - 30 M / minute until the length of each roll is about 3000 - 10000 meters (m), and then the production stops. Step 4: Take out the finished product from the winding, and return to Step 1 to continue production to achieve the purpose of mass production. In summary, the lithium - battery negative electrode of the present invention is manufactured in a drying chamber, and through the electroplating wheel set in the drying chamber, lithium metal can be continuously deposited on the copper foil in the electroplating tank to form a copper - lithium alloy metal layer. Also, through the film - laminating wheel set in the drying chamber, the protective film can be continuously attached to the copper - lithium alloy metal layer pulled out from the electroplating tank. In this way, the copper foil and the protective film with low reactivity can effectively reduce the probability of lithium metal oxidation. Therefore, the manufactured composite negative electrode structure can effectively improve the performance of lithium batteries and is conducive to mass production. Although the present invention has been disclosed as above with embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains, without departing from the spirit and scope of the present invention, may make some modifications and refinements. Therefore, the protection scope of the present invention shall be subject to that defined by the appended patent application scope. 10: Copper foil 20: Lithium metal layer 30: Protective film 100: Electroplating equipment 110: Drying chamber 111: Electroplating tank 111a: First electrode 112: Electroplating wheel set 112a: First guide wheel 112b: Second guide wheel 112c: First conductive wheel 112d: Second conductive wheel 113: Film sticking wheel set 113a: Third guide wheel 113b: Pressing and laminating wheel 114: Copper foil supply device 115: Protective film device 116: Drying device 116a: First drying device 116b: Second drying device 117: Rewinding device E: Environment S100, S200, S300, S400: Steps Figure 1 is a flowchart of a method for manufacturing a negative electrode of a lithium battery according to an embodiment of the present invention. Figure 2 is a schematic diagram of an electroplating device according to an embodiment of the present invention. Figure 3 is a cross-sectional schematic diagram of a negative electrode of a lithium battery according to an embodiment of the present invention. Figure 4 is a cross-sectional schematic diagram of a negative electrode of a lithium battery according to another embodiment of the present invention. S100, S200, S300, S400: Steps

Claims

1. A method for manufacturing a lithium battery negative electrode, comprising: An electroplating apparatus is provided, wherein the electroplating apparatus has a drying chamber, and the drying chamber includes an electroplating tank, an electroplating wheel assembly, a film-applying wheel assembly, a copper foil supply device connected to the electroplating wheel assembly, and a protective film supply device in the form of rollers connected to the film-applying wheel assembly, wherein: the electroplating wheel assembly includes: a first guide wheel and a second guide wheel disposed in the electroplating tank, wherein the first guide wheel and the second guide wheel are configured such that the copper foil in the electroplating tank is parallel to a first electrode; and a first conductive wheel and a second conductive wheel disposed outside the electroplating tank, wherein the first conductive wheel and the second conductive wheel serve as a second electrode; the film-applying wheel assembly includes a third guide wheel connected to the second conductive wheel and a pressing and bonding wheel connected to the third guide wheel; and copper foil is disposed in the drying chamber; The electroplating rollers transport the copper foil to form a lithium metal layer on the copper foil, and the copper foil and the lithium metal layer constitute a copper-lithium composite metal layer. After the copper foil undergoes an electroplating process to deposit lithium metal onto the copper foil to form the copper-lithium composite metal layer, it leaves the electroplating tank and is drawn to the second conductive roller. The thickness of the copper foil is between 6 micrometers and 35 micrometers, and the thickness of the lithium metal layer is between 0.5 micrometers and 20 micrometers. The film-applying rollers transport the copper-lithium composite metal layer and apply a protective film to the copper-lithium composite metal layer. The material of the protective film includes an aluminum composite film, and the aluminum composite film is an aluminum foil with a thickness between 6 micrometers and 35 micrometers with a non-stretch polypropylene film applied on it.

2. The method for manufacturing a lithium battery negative electrode as claimed in claim 1, wherein the drying chamber further includes a drying device, and the drying device is configured to remove organic solvents from the copper-lithium composite metal layer.

3. The method for manufacturing a lithium battery negative electrode as claimed in claim 1, wherein the drying apparatus includes an air knife, rollers, an infrared heater, or a combination thereof.

4. The method for manufacturing a lithium battery negative electrode as claimed in claim 1, wherein the environment of the drying chamber is composed of an inert gas.

5. The method for manufacturing a lithium battery negative electrode as claimed in claim 1, wherein the protective film at least completely covers the surface of the lithium metal layer.

6. The method for manufacturing a lithium battery negative electrode as claimed in claim 1, wherein the protective film directly contacts the lithium metal layer and the copper foil.

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

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