KR-20260067509-A - release film for transcribing lithium and method for manufacturing thereof

KR20260067509AKR 20260067509 AKR20260067509 AKR 20260067509AKR-20260067509-A

Abstract

The present invention relates to a lithium transfer release film and a method for manufacturing the same. More specifically, the invention relates to a release film for transferring lithium (Li) to a current collector of a battery after depositing lithium (Li) on the release film, wherein the deposition efficiency is excellent by minimizing the occurrence of pinholes when depositing lithium (Li) on the release film, and the efficiency of transferring the lithium deposited on the release film to the current collector is excellent. Furthermore, the invention relates to an environmentally friendly lithium transfer release film and a method for manufacturing the same, wherein the release film uses an environmentally friendly substrate and uses water instead of an organic solvent during manufacturing.

Inventors

한은정
김용규
김재용
장남윤
전승환
황보격

Assignees

율촌화학 주식회사

Dates

Publication Date: 20260513
Application Date: 20241105

Claims (11)

A lithium transfer release film comprising: a base film; and a release layer formed on one surface of the base film; The above base film is a recycled PET (Recycled Polyethylene terephthalate) film or a bio-PET (Bio-Polyethylene terephthalate) film, and A lithium transfer release film characterized by the fact that, after depositing lithium to a thickness of 2 to 25 μm on one surface of the release layer, when white light is irradiated onto the base film, 100 or fewer pinholes occur per unit area of 10 cm x 10 cm in the deposited lithium.
In paragraph 1, The above release layer comprises a resin composition, and A lithium transfer release film characterized by the above resin composition containing 10 to 70 weight percent of a silicone-based resin based on the total weight percent.
In paragraph 2, A lithium transfer release film characterized by the above release layer comprising 0.1 to 5 parts by weight of a catalyst and 0.1 to 5 parts by weight of an adhesion enhancer per 100 parts by weight of a resin composition.
In paragraph 1, A lithium transfer release film characterized by the above release layer containing 2 to 5 weight percent of silicon (Si) based on the total weight percent.
In paragraph 1, The surface tension of the above release layer is 25 to 30 dyne, and The release force of the above release layer is 33 to 44 gf/inch, and A lithium transfer release film characterized by the water contact angle of the release layer being 95 to 105°.
In paragraph 2, The above resin composition includes a silicone-based resin and a non-silicone-based resin, and The above silicone-based resin comprises one or more types selected from addition-reaction type silicone-based resins, condensation-reaction type silicone-based resins, and UV-reaction type silicone-based resins, and A lithium transfer release film characterized by comprising one or more types selected from cellulose resin, acrylate resin, melamine resin, and alkyd resin.
In paragraph 1, A lithium transfer release film characterized by the fact that, after depositing lithium to a thickness of 2 to 8 μm on one surface of the release layer, white light is irradiated onto the base film, and the number of pinholes in the deposited lithium is 100 or fewer per unit area of 10 cm x 10 cm.
Step 1: preparing a base film; and A second step of forming a release layer by applying a composition for forming a release layer to one surface of the base film and then curing it; comprising The above base film is a recycled PET (Recycled Polyethylene terephthalate) film or a bio-PET (Bio-Polyethylene terephthalate) film, and A method for manufacturing a lithium transfer release film characterized by depositing lithium to a thickness of 2 to 25 μm on one surface of the release layer, and then irradiating the base film with white light, such that 100 or fewer pinholes occur per unit area of 10 cm x 10 cm in the deposited lithium.
In paragraph 8, The above-mentioned composition for forming a release layer is a mixture of a resin composition, a catalyst, an adhesion enhancer, and water, and A method for manufacturing a lithium transfer release film, characterized in that the resin composition comprises 10 to 70 weight percent of a silicone-based resin mixed with respect to the total weight percent.
In Paragraph 9, A method for manufacturing a lithium transfer release film, characterized in that the above-mentioned composition for forming a release layer is mixed with 0.1 to 5 parts by weight of a catalyst, 0.1 to 5 parts by weight of an adhesion enhancer, and 800 to 1000 parts by weight of water, based on 100 parts by weight of a resin composition.
In paragraph 8, A method for manufacturing a lithium transfer release film characterized by performing the above curing at a temperature of 120 to 160°C for 10 to 60 seconds.

Description

Release film for transcribing lithium and method for manufacturing thereof The present invention relates to a lithium transfer release film and a method for manufacturing the same. More specifically, the invention relates to a release film for transferring lithium (Li) to a current collector of a battery after depositing lithium (Li) on the release film, wherein the deposition efficiency is excellent by minimizing the occurrence of pinholes when depositing lithium (Li) on the release film, and the efficiency of transferring the lithium deposited on the release film to the current collector is excellent. Furthermore, the invention relates to an environmentally friendly lithium transfer release film and a method for manufacturing the same, wherein the release film uses an environmentally friendly substrate and uses water instead of an organic solvent during manufacturing. In batteries, specifically secondary batteries, the battery capacity is reduced compared to the theoretical capacity of the anode material because a large proportion of the lithium ions released from the positive electrode during the first charge remain adsorbed on the negative electrode. To avoid such irreversible capacity loss, a technique has been disclosed in which lithium equivalent to the irreversible capacity loss is adsorbed on the negative electrode in advance, and then the secondary battery is assembled and charging and discharging are initiated. By utilizing this technique, a high proportion of lithium ions released from the positive electrode during the first charge can be recovered to the negative electrode, thereby increasing the battery capacity. Meanwhile, as a common method for pre-absorbing lithium onto the cathode, a method of depositing lithium onto the cathode is being used. In order to deposit lithium equivalent to an irreversible capacity, a method is being studied to increase the amount of lithium deposited by pre-treating a graphite material or a silicon graphite material onto a current collector. However, graphite materials have a capacity limit when lithium ions move, and silicon graphite materials are highly likely to cause problems with battery durability due to rapid volume expansion during lithium ion movement. For this reason, there is a need to develop a new method to pre-charge a sufficient amount of lithium into the cathode and/or prevent volume expansion due to an increase in the amount of lithium, and as one such method, a method is being attempted in which lithium metal is deposited on a release film and then transferred to a current collector, preferably a cathode current collector. In conclusion, regarding the method of depositing lithium on a release film and then transferring it to a current collector, there is a need for measures to ensure uniform lithium deposition and high transfer efficiency. FIG. 1 is a cross-sectional view showing a lithium transfer release film on one side according to a preferred embodiment of the present invention. FIG. 2 is a schematic diagram showing the observation of pinholes occurring in the deposited lithium after depositing lithium on one surface of a release layer according to a preferred embodiment of the present invention and then irradiating a base film with white light. Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts unrelated to the explanation have been omitted to clearly explain the present invention, and the same reference numerals are assigned to identical or similar components throughout the specification. Referring to FIG. 1, the lithium transfer release film of the present invention may include a base film (10) and a release layer (20) formed on one surface of the base film (10). The base film (10) is a film that serves as a substrate film when coating the release layer (20) or depositing lithium (Li), and any base film material used in the industry can be used, preferably a recycled PET (Recycled Polyethylene terephthalate) film or a bio-PET (Bio-Polyethylene terephthalate) film, and more preferably a recycled PET (Recycled Polyethylene terephthalate) film. Recycled PET film, also known as PCR (Post-Consumer Recycled)-PET film, refers to PET materials (such as PET bottles and PET containers) that have been discarded by end consumers after use, which are then crushed and made into a film. Therefore, by recycling PET materials that were at risk of being landfilled or incinerated, landfilling and incineration can be reduced, thereby reducing carbon and electrical energy. Accordingly, in the present invention, by using a recycled PET (Recycled Polyethylene terephthalate) film instead of a general PET film as the base film (10), an eco-friendly lithium transfer release film ca