Search

KR-102961970-B1 - METHOD FOR MANUFACTURING NEGATIVE ELECTRODE

KR102961970B1KR 102961970 B1KR102961970 B1KR 102961970B1KR-102961970-B1

Abstract

The present invention relates to a method for manufacturing a cathode comprising: (a) preparing a cathode roll wound with a cathode structure comprising a cathode current collector and a cathode active material layer formed on at least one surface of the cathode current collector; (b) while unwinding the cathode structure from the cathode roll, joining a pre-lithiated structure, which is composed of a polymer film and a lithium metal layer formed on the polymer film, to the cathode structure such that the lithium metal layer and the cathode active material layer face each other; (c) pressing the cathode structure joined with the pre-lithiated structure; and (d) after the pressing step, winding the cathode structure joined with the pre-lithiated structure onto a recovery roll and storing it.

Inventors

  • 최정훈
  • 장민철
  • 엄인성
  • 정병효
  • 강용희

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260508
Application Date
20200123

Claims (11)

  1. (a) a step of preparing a cathode roll wound with a cathode structure comprising a cathode current collector and a cathode active material layer formed on at least one surface of the cathode current collector; (b) a step of unwinding the cathode structure from the cathode roll and bonding a pre-lithiated structure, which consists of a polymer film and a lithium metal layer formed on the polymer film, to the cathode structure such that the lithium metal layer and the cathode active material layer face each other; (c) a step of applying pressure to the cathode structure to which the above-mentioned pre-lithiation structure is bonded; (d) after the pressurizing step, winding the cathode structure bonded with the pre-lithiated structure onto a recovery roll and storing it for 6 to 30 hours; and (e) a step of separating the polymer film from the cathode structure after step (d); comprising, The thickness of the lithium metal layer is 1 μm to 10 μm, and The polymer film and the lithium metal layer are in contact with each other, In the above-mentioned prelithiated structure, there is no release film between the polymer film and the lithium metal layer, and The above-mentioned pre-lithiated structure is a method for manufacturing a cathode by forming a lithium metal layer by vapor deposition of lithium metal on the polymer film.
  2. delete
  3. In claim 1, A method for manufacturing a cathode in which, in step (d) above, lithium in the lithium metal layer is injected into the cathode active material layer.
  4. In claim 1, A method for manufacturing a cathode in which the above-mentioned pressurization is performed at 75 kgf/ cm² to 550 kgf/ cm² .
  5. delete
  6. In claim 1, The above storage is a method for manufacturing a cathode performed at 20℃ to 80℃.
  7. In claim 1, A method for manufacturing a cathode comprising at least one selected from the group consisting of polyethylene terephthalate, triacetylcellulose, polyacrylate, and polyimide, wherein the polymer film above.
  8. In claim 1, A method for manufacturing a cathode in which the thickness of the polymer film is 20㎛ to 100㎛.
  9. delete
  10. delete
  11. In claim 1, The above-mentioned negative electrode active material layer includes a negative electrode active material, and A method for manufacturing a cathode in which the above-mentioned cathode active material is at least one selected from silicon-based active materials and carbon-based active materials.

Description

Method for Manufacturing Negative Electrode The present invention relates to a method for manufacturing a cathode. With the recent rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for small, lightweight, and relatively high-capacity rechargeable batteries is increasing rapidly. In particular, lithium-ion batteries are gaining prominence as power sources for portable devices due to their lightweight nature and high energy density. Consequently, active research and development efforts are underway to improve the performance of lithium-ion batteries. The above lithium secondary battery generally includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte, an organic solvent, etc. Additionally, an active material layer comprising a positive active material or a negative active material may be formed on a current collector for the positive electrode and the negative electrode. For the positive electrode, a lithium - containing metal oxide such as LiCoO2 or LiMn2O4 is generally used as the positive active material, and accordingly, a carbon-based material or a silicon-based material that does not contain lithium is used as the negative active material for the negative electrode. In the case of such anodes, a passivation film, such as a solid electrolyte interface layer (SEI layer), is formed on the anode surface during initial charging. This passivation film hinders the insertion of organic solvents into the anode and suppresses the decomposition reaction of organic solvents, thereby stabilizing the anode structure, improving the anode's reversibility, and enabling its use as an anode. However, since the formation reaction of the passivation film is irreversible, it leads to the consumption of lithium ions, which reduces the battery's capacity. Furthermore, as the battery cycle is repeated, the consumption of lithium ions results in a decrease in capacity and a reduction in cycle life. Accordingly, a method is being developed to prevent capacity degradation and improve cycle life by pre-lithiating the cathode surface by means of a method such as inserting lithium into the cathode, thereby forming a passivation film in advance. As an example of a pre-lithiation method, there is a method in which lithium metal is vapor-deposited onto the cathode and then diffused into the cathode by applying pressure. However, the method of vapor-depositing lithium metal onto the cathode has the disadvantage of not being suitable for mass production of cathodes because it is not suitable for roll-to-roll processes. In addition, as another example of a pre-lithiation method, there is a method in which a structure comprising a release film interposed between a polymer film and a lithium metal layer is bonded to the cathode, the polymer film and the release film are removed to transfer the lithium metal layer onto the cathode, and lithium is diffused into the cathode by applying pressure. While this method is applicable to some extent in roll-to-roll processes, there is a problem in that the release film is not completely removed and remains during the process of transferring the lithium metal layer to the cathode. The release film remaining on the cathode is undesirable as it causes an increase in cathode resistance or a decrease in lifespan characteristics. Therefore, there is a need to develop a manufacturing method for a cathode with improved quality that is suitable for roll-to-roll processes while achieving the goal of full lithiumization. Korean Registered Patent No. 10-0291067 discloses a method for pre-lithiation of a carbon electrode and a method for manufacturing a lithium secondary battery using the same. FIG. 1 is a diagram for schematically explaining the method of manufacturing a cathode of the present invention. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. In this specification, the average particle size (D 50 ) can be defined as the particle size correspond