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CN-121986133-A - Release film for lithium transfer and method for producing same

CN121986133ACN 121986133 ACN121986133 ACN 121986133ACN-121986133-A

Abstract

The present invention relates to a release film for lithium transfer and a method for manufacturing the same, and more particularly, to a release film for lithium transfer, which is used to transfer lithium (Li) onto a battery current collector after depositing the same on a release film, and which can minimize the generation of pinholes (pin holes) when depositing lithium (Li) onto the release film, and which is excellent in not only deposition efficiency but also transfer efficiency of lithium deposited on the release film to the current collector, and a method for manufacturing the same.

Inventors

  • ZHANG NANYUN
  • HUANGFU KUI
  • Qian Chenghuan
  • Jin Longkui
  • Pian Zhengmin
  • JIN DONGBIN

Assignees

  • 栗村化学株式会社

Dates

Publication Date
20260505
Application Date
20241010
Priority Date
20231113

Claims (12)

  1. 1. A release film for lithium transfer, comprising: A base film, and A release layer formed on one surface of the base film; The method is characterized in that when the white light is irradiated to the base film after lithium is deposited on one surface of the release layer at a thickness of 2-25 [ mu ] m, pinholes are 100 or less per 10cm x 10cm unit area in the deposited lithium.
  2. 2. The release film for lithium transfer according to claim 1, wherein, The release layer comprises a resin composition, Wherein the resin composition comprises 10 to 70 wt% of a silicone resin based on the total weight%.
  3. 3. The release film for lithium transfer according to claim 2, wherein, The release layer comprises 0.1-5 parts by weight of catalyst and 0.1-5 parts by weight of adhesion improver relative to 100 parts by weight of the resin composition.
  4. 4. The release film for lithium transfer according to claim 1, wherein, The release layer comprises 2-5 wt% of silicon (Si) based on the total weight percent.
  5. 5. The release film for lithium transfer according to claim 1, wherein, The surface tension of the release layer is 25-30 dyne, The release force of the release layer is 33-44 gf/inch, The water contact angle of the release layer is 95-105 degrees.
  6. 6. The release film for lithium transfer according to claim 1, wherein, The base film comprises more than one selected from polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyimide (PI) and Polyethylene (PE).
  7. 7. The release film for lithium transfer according to claim 2, wherein, The resin composition includes a silicone-based resin and a non-silicone-based resin, The silicone resin includes at least 1 kind selected from addition reaction type silicone resins, condensation reaction type silicone resins and UV reaction type silicone resins, The non-silicone resin includes at least 1 selected from cellulose resins, acrylate resins, melamine resins, and alkyd resins.
  8. 8. The release film for lithium transfer according to claim 1, wherein, When the white light is irradiated to the base film after lithium is deposited on one surface of the release layer at a thickness of 2 to 8 [ mu ] m, the number of pinholes per 10cm×10cm unit area in the deposited lithium is 100 or less.
  9. 9. A method for manufacturing a release film for lithium transfer, comprising the steps of: a first step of preparing a base film, and A second step of coating a release layer-forming composition on one surface of the base film, and then curing the composition to form a release layer; The method is characterized in that when the white light is irradiated to the base film after lithium is deposited on one surface of the release layer at a thickness of 2-25 [ mu ] m, pinholes are 100 or less per 10cm x 10cm unit area in the deposited lithium.
  10. 10. The method for producing a release film for lithium transfer according to claim 9, wherein, The composition for forming the release layer is formed by mixing a resin composition, a catalyst, an adhesive force improver and a solvent, The resin composition contains 10 to 70 wt% of a silicone resin based on the total weight%.
  11. 11. The method for producing a release film for lithium transfer according to claim 10, wherein, The release layer forming composition is prepared by mixing 0.1-5 parts by weight of a catalyst, 0.1-5 parts by weight of an adhesion improver and 800-1000 parts by weight of a solvent with respect to 100 parts by weight of the resin composition.
  12. 12. The method for producing a release film for lithium transfer according to claim 9, wherein, The curing is carried out at a temperature of 100-140 ℃ for 10-40 seconds.

Description

Release film for lithium transfer and method for producing same Technical Field The present invention relates to a release film for lithium transfer and a method for manufacturing the same, and more particularly, to a release film for lithium transfer, which is used to transfer lithium (Li) onto a battery current collector after depositing the same on a release film, and which can minimize the generation of pinholes (pin holes) when depositing lithium (Li) onto the release film, and which is excellent in not only deposition efficiency but also transfer efficiency of lithium deposited on the release film to the current collector, and a method for manufacturing the same. Background In a battery, specifically, a secondary battery, since a proportion of lithium ions released from a positive electrode at the time of initial charge is large to be inserted into a negative electrode, the battery capacity is small compared with the theoretical capacity of a negative electrode material. In order to avoid such irreversible capacity loss, a technique has been disclosed in which lithium in an amount corresponding to the irreversible capacity loss is previously inserted into the negative electrode, and then the secondary battery is assembled and charge and discharge are started. By using the above method, lithium ions released from the positive electrode at the time of the first charge can be recovered to the negative electrode at a high ratio, and thus the battery capacity increases. On the other hand, as a general method of inserting lithium into a negative electrode in advance, a method of depositing lithium into a negative electrode is adopted. In order to deposit lithium equivalent to irreversible capacity, a method of pretreating a graphite material or a silica ink material on a current collector to increase the amount of deposited lithium is being studied. However, there is a limit in the capacity of the graphite material at the time of lithium ion movement, and the silicon graphite material causes a sharp volume expansion at the time of lithium ion movement, thereby possibly causing a problem in durability of the battery. For the above reasons, there is a need to develop a method of pre-charging a sufficient amount of lithium into a negative electrode and/or a new method capable of preventing volume expansion due to an increase in the amount of lithium, wherein one method is to deposit lithium metal on a release film and then transfer it to a current collector, preferably a negative electrode current collector. In view of the foregoing, regarding the manner in which lithium is transferred to a current collector after being deposited on a release film, there is a need for a solution that ensures uniform deposition and high transfer efficiency of lithium. Disclosure of Invention Technical problem to be solved by the invention The present invention has been made to solve the above problems, and an object thereof is to provide a release film for lithium transfer capable of ensuring uniform deposition performance and transfer to efficiency, and a method for manufacturing the same. Means for solving the problems In order to solve the above problems, the release film for lithium transfer of the present invention may include a base film and a release layer formed on one side of the base film. In a preferred embodiment of the present invention, after lithium is deposited on one side of the release layer in a thickness of 2 to 25 μm, when white light (WHITE LIGHT) is irradiated to the base film, pinholes (pin holes) generated per 10cm×10cm unit area in the deposited lithium may be 100 or less. In a preferred embodiment of the present invention, after lithium is deposited on one side of the release layer in a thickness of 2 to 8 μm, when white light (WHITE LIGHT) is irradiated to the base film, pinholes (pin holes) generated per 10cm×10cm unit area in the deposited lithium may be 100 or less. In a preferred embodiment of the present invention, the release layer may include a resin composition. In a preferred embodiment of the present invention, the resin composition may include 10 to 70 wt% of the silicone-based resin based on the total weight%. In a preferred embodiment of the present invention, the release layer may include 0.1 to 5 parts by weight of a catalyst and 0.1 to 5 parts by weight of an adhesion promoter with respect to 100 parts by weight of the resin composition. In a preferred embodiment of the present invention, the release layer may include 2 to 5 wt% of silicon (Si) based on the total weight%. In a preferred embodiment of the present invention, the surface tension of the release layer may be 25 to 30dyne. In a preferred embodiment of the present invention, the release force of the release layer may be 33 to 44gf/inch. In a preferred embodiment of the present invention, the water contact angle of the release layer may be 95 to 105 °. In a preferred embodiment of the present invention, the base film may be t