Release film for transferring lithium and manufacturing method for same

Abstract

The present invention relates to a release film for transferring lithium and a manufacturing method for same and, more specifically, to: a release film for transferring lithium, by lithium (Li) being deposited on the release film and then transferred to a current collector of a battery, wherein when lithium (Li) is deposited on the release film, the generation of pin holes is minimized, resulting in an excellent deposition efficiency and excellent transfer efficiency of the lithium deposited on the release film to the current collector; and a manufacturing method for same.

Description

Lithium transfer film and method for manufacturing the same

[0001] The present invention relates to a lithium transfer release film and a method for manufacturing the same, and more particularly, to a release film for depositing lithium (Li) on a release film and then transferring it to a current collector of a battery, wherein when lithium (Li) is deposited on the release film, the occurrence of pin holes is minimized, thereby ensuring excellent deposition efficiency, and further, the lithium transfer release film and a method for manufacturing the same are excellent in the efficiency of transferring lithium deposited on the release film to a current collector.

[0002]

[0003] Batteries, specifically secondary batteries, exhibit reduced battery capacity compared to the theoretical capacity of the anode material because a significant portion of the lithium ions released from the positive electrode during the first charge remain stored in the negative electrode. To avoid this irreversible capacity loss, a technique has been disclosed in which a significant portion of the irreversible capacity loss is preliminarily stored in the negative electrode, after which the secondary battery is assembled and charged and discharged. By utilizing this technique, a high percentage of the lithium ions released from the positive electrode during the first charge can be recovered to the negative electrode, thereby increasing battery capacity.

[0004] Meanwhile, a common method for pre-loading lithium into the anode is to deposit lithium on the anode. To deposit lithium sufficient for a significant irreversible capacity, research is being conducted on methods for increasing the amount of lithium deposited by pre-treating the current collector with graphite or silicon graphite materials.

[0005] However, graphite materials have limited capacity when lithium ions move, and silicon graphite materials cause rapid volume expansion when lithium ions move, which is likely to cause problems with battery durability.

[0006] For this reason, there is a need to develop a new method for pre-charging a sufficient amount of lithium to the negative electrode and / or for preventing volume expansion due to an increase in the amount of lithium. As one of these methods, a method of depositing lithium metal on a release film and then transferring it to a current collector, preferably an anode current collector, is being attempted.

[0007] In conclusion, with regard to the method of depositing lithium on a heteromorphic film and then transferring it to a current collector, a method is needed to ensure uniform deposition of lithium and high transfer efficiency.

[0008]

[0009] The present invention has been devised to solve the above problems, and its purpose is to provide a lithium transfer release film capable of securing uniform deposition performance and transfer efficiency, and a method for manufacturing the same.

[0010]

[0011] In order to solve the above-described problem, the lithium transfer release film of the present invention may include a base film and a release layer formed on one surface of the base film.

[0012] In a preferred embodiment of the present invention, when lithium is deposited on one side of the release layer of the lithium transfer film of the present invention to a thickness of 2 to 25 μm and then white light is irradiated on the base film, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0013] In a preferred embodiment of the present invention, when lithium is deposited on one surface of a release layer of a lithium transfer film of the present invention to a thickness of 2 to 8 ㎛ and white light is irradiated on the base film, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0014] In a preferred embodiment of the present invention, the heterogeneous layer may include a resin composition.

[0015] In a preferred embodiment of the present invention, the resin composition may contain 10 to 70 wt% of a silicone resin based on the total wt%.

[0016] 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 enhancer per 100 parts by weight of the resin composition.

[0017] In a preferred embodiment of the present invention, the heterostructure layer may contain 2 to 5 wt% of silicon (Si) based on the total wt%.

[0018] In a preferred embodiment of the present invention, the surface tension of the heterogeneous layer may be 25 to 30 dyne.

[0019] In a preferred embodiment of the present invention, the release force of the release layer may be 33 to 44 gf / inch.

[0020] In a preferred embodiment of the present invention, the water contact angle of the heterogeneous layer may be 95 to 105°.

[0021] In a preferred embodiment of the present invention, the base film may include at least one selected from PET (Polyethylene terephthalate), PP (Polypropylene), PBT (Polybutyleneterephthalate), PEN (Polyethylene naphthalate), PI (Polyimide), and PE (Polyethylene).

[0022] In a preferred embodiment of the present invention, the resin composition may include a silicone-based resin and a non-silicone-based resin.

[0023] In a preferred embodiment of the present invention, the silicone resin may include at least one selected from an addition-reaction type silicone resin, a condensation-reaction type silicone resin, and a UV-reaction type silicone resin.

[0024] In a preferred embodiment of the present invention, the non-silicone resin may include at least one selected from a cellulose resin, an acrylate resin, a melamine resin, and an alkyd resin.

[0025] Meanwhile, the method for manufacturing a lithium transfer release film of the present invention includes a first step of preparing a base film, and a second step of applying a composition for forming a release layer on one surface of the base film and then curing the composition to form a release layer, and when lithium is deposited on one surface of the release layer to a thickness of 2 to 8 ㎛ and white light is irradiated on the base film, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0026] In a preferred embodiment of the present invention, the composition for forming a heterolayer may be a mixture of a resin composition, a catalyst, an adhesion enhancer, and a solvent.

[0027] In a preferred embodiment of the present invention, the resin composition may be a mixture of 10 to 70 wt% of silicone resin based on the total wt%.

[0028] In a preferred embodiment of the present invention, the composition for forming a heterogeneous layer may be a mixture of 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 a solvent, per 100 parts by weight of a resin composition.

[0029] In a preferred embodiment of the present invention, curing can be performed at a temperature of 100 to 140°C for 10 to 40 seconds.

[0030]

[0031] The lithium transfer release film of the present invention and the method for manufacturing the same are release films for depositing lithium (Li) on the release film and then transferring it to a current collector of a battery, and can increase the capacity of a secondary battery by preliminarily absorbing lithium equivalent to the amount of lithium ions irreversibly lost during the first charge and discharge of a secondary battery into a negative current collector.

[0032] In addition, the lithium transfer film of the present invention and its manufacturing method have excellent deposition efficiency by minimizing the occurrence of pin holes when depositing lithium (Li) on the release film.

[0033] In addition, the lithium transfer film and the method for manufacturing the same of the present invention have excellent efficiency in transferring lithium deposited on the release film to a current collector.

[0034]

[0035] FIG. 1 is a cross-sectional view showing a lithium transfer film on one side according to a preferred embodiment of the present invention.

[0036] FIG. 2 is a schematic diagram showing a preferred embodiment of the present invention in which lithium is deposited on one surface of a heterostructure layer, and then white light is irradiated on the base film to observe pinholes occurring in the deposited lithium.

[0037]

[0038] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description have been omitted for clarity of description, and the same reference numerals are assigned to identical or similar components throughout the specification.

[0039]

[0040] Referring to FIG. 1, the lithium transfer 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).

[0041] The base film (10) is a film that serves as a base film when coating a release layer (20) or depositing lithium (Li). Any material used in the art as a base film can be used, and preferably, it can include at least one selected from among PET (Polyethylene terephthalate), PP (Polypropylene), PBT (Polybutylene terephthalate), PEN (Polyethylene naphthalate), PI (Polyimide), and PE (Polyethylene), and more preferably, it can include PET.

[0042] In addition, the base film (10) of the present invention may have a thickness of 10 to 250 ㎛, preferably 25 to 100 ㎛. If the thickness is less than 10 ㎛, there may be a problem of thermal deformation occurring in the base film (10) during a lithium (Li) deposition process performed at high temperature, and if it exceeds 250 ㎛, there may be a problem of economic feasibility.

[0043] The hetero layer (20) is a layer that uniformly deposits lithium (Li) or smoothly transfers lithium (Li) to a current collector, and is a layer on which lithium is deposited on one side to transfer lithium.

[0044] The heterogeneous layer (20) may have a thickness of 0.01 to 1 ㎛, preferably 0.05 to 0.5 ㎛. If the thickness is less than 0.01 ㎛, there may be a problem of poor transfer, and if it exceeds 1 ㎛, there may be a problem of blocking during winding.

[0045] The release layer (20) may include a resin composition, and the resin composition may include a silicone resin in an amount of 10 to 70 wt%, preferably 30 to 70 wt%, more preferably 45 to 70 wt%, and even more preferably 55 to 65 wt%, based on the total weight%. If the silicone resin is included in an amount of less than 10 wt%, there may be a problem in that the lithium transfer efficiency is significantly reduced, and if it is included in an amount exceeding 70 wt%, there may be a problem in that the occurrence rate of pin holes in the deposited lithium increases when lithium is deposited on one surface of the release layer.

[0046] Meanwhile, the silicone resin may include at least one selected from an addition reaction type silicone resin, a condensation reaction type silicone resin, and a UV reaction type silicone resin, and preferably may include an addition reaction type silicone resin.

[0047] In addition, the resin composition may include a silicone-based resin and a non-silicone-based resin, and the non-silicone-based resin may be included in an amount of 30 to 90 wt%, preferably 30 to 70 wt%, more preferably 30 to 55 wt%, and even more preferably 35 to 45 wt%, based on the total weight of the resin composition.

[0048] In addition, the non-silicon-based resin is a resin that does not contain silicon (Si) as a component, and may include at least one selected from among cellulose-based resin, acrylate-based resin, melamine-based resin, and alkyd-based resin, and preferably may include cellulose resin.

[0049] In addition, the release layer (20) may contain 2 to 5 wt%, preferably 3 to 5 wt%, more preferably 3.3 to 5 wt%, and even more preferably 3.8 to 4.9 wt%, of silicon (Si) based on the total weight%. If it contains less than 2 wt% of silicon, there may be a problem in which lithium transfer efficiency is significantly reduced, and if it contains more than 5 wt%, there may be a problem in which the occurrence rate of pin holes in the deposited lithium increases when lithium is deposited on one surface of the release layer.

[0050] Furthermore, the release layer (20) may contain 0.1 to 5 parts by weight of the catalyst, preferably 0.5 to 3.0 parts by weight, and more preferably 1.0 to 2.0 parts by weight, based on 100 parts by weight of the resin composition. If the catalyst is contained in an amount of less than 0.1 parts by weight, there may be a problem of non-curing, and if it exceeds 5 parts by weight, there may be a problem of significantly increased peeling strength.

[0051] Additionally, any catalyst commonly used in the art may be used as the catalyst, and preferably may include platinum.

[0052] Furthermore, the release layer (20) may contain 0.1 to 5 parts by weight, preferably 0.5 to 3.0 parts by weight, and more preferably 0.5 to 1.5 parts by weight, of an adhesion enhancer with respect to 100 parts by weight of the resin composition. If the adhesion enhancer is contained in an amount less than 0.1 parts by weight, there may be a problem of poor adhesion between the release layer (20) and the base film (10), and if it exceeds 5 parts by weight, there may be a problem of silicon (Si) contained in the release layer (20) being transferred to the back surface of the base film (10).

[0053] The adhesion enhancer is a material that plays a role in improving the adhesion between the release layer (20) and the base film (10). Any adhesion enhancer commonly used in the art can be used, and preferably, it can include methylvinyl siloxane with dimethyl epoxide.

[0054]

[0055] Meanwhile, referring to FIG. 2, the lithium transfer release film of the present invention deposits lithium (30) on one side of the release layer (20) to a thickness of 2 to 25 μm, preferably 2 to 20 μm, more preferably 2 to 15 μm, even more preferably 2 to 8 μm, even more preferably 3 to 7 μm, and even more preferably 4 to 6 μm, and then when white light is irradiated on the base film (10), 100 or fewer pin holes per unit area of ​​10 cm x 10 cm may be generated in the deposited lithium (30). Pin holes refer to pores generated in the lithium (30) during deposition. If more than 100 pin holes per unit area of ​​10 cm x 10 cm are generated in the lithium (30), there may be a problem that the lithium (30) is not deposited uniformly. Also, white light refers to light with a wavelength of 400 to 700 nm.

[0056] In addition, the release film for lithium transfer of the present invention may have a surface tension of the release layer (20) of 25 to 30 dyne, preferably 25 to 28 dyne. If the surface tension is less than 25 dyne, there may be a problem of many pin holes occurring during lithium deposition, and if it exceeds 30 dyne, there may be a problem of reduced transfer efficiency when transferring lithium to a current collector.

[0057] In addition, the release film for lithium transfer of the present invention may have a release force of the release layer (20) of 33 to 44 gf / inch, preferably 33 to 40 gf / inch, and more preferably 34 to 36 gf / inch. If the release force is less than 33 gf / inch, there may be a problem of many pin holes occurring during lithium deposition, and if it exceeds 44 gf / inch, there may be a problem of reduced transfer efficiency when transferring lithium to a current collector.

[0058] In addition, the lithium transfer release film of the present invention may have a water contact angle of the release layer (20) of 95 to 105°, preferably 100 to 105°. If the water contact angle is less than 95°, there may be a problem of reduced transfer efficiency when transferring lithium to a current collector, and if it exceeds 105°, there may be a problem of many pin holes occurring when lithium is deposited.

[0059]

[0060] Furthermore, the method for manufacturing a lithium transfer film of the present invention includes a first step and a second step.

[0061] First, in the first step of the method for manufacturing a lithium transfer film of the present invention, a base film can be prepared. At this time, the base film is as described above.

[0062] Next, in the second step of the method for manufacturing a lithium transfer film of the present invention, a composition for forming a release layer is applied to one surface of the base film prepared in the first step, and then cured to form a release layer.

[0063] The composition for forming a release layer may be a mixture of a resin composition, a catalyst, an adhesion promoter, and a solvent. Specifically, the composition for forming a release layer may be a mixture of 0.1 to 5 parts by weight of a catalyst, preferably 0.5 to 3.0 parts by weight, and more preferably 1.0 to 2.0 parts by weight, 0.1 to 5 parts by weight of a adhesion promoter, preferably 0.5 to 3.0 parts by weight, and more preferably 0.5 to 1.5 parts by weight, and 800 to 1000 parts by weight of a solvent, preferably 850 to 950 parts by weight, per 100 parts by weight of the resin composition. At this time, the catalyst and the adhesion promoter are as described above. In addition, the solvent may be any solvent generally used in the art, and preferably may include at least one selected from toluene, MEK (Methyl Ethyl Keton), n-Hexane, and MIBK (Methyl Isobutyl Keton).

[0064] In addition, the resin composition may be a mixture of a silicone-based resin and a non-silicone-based resin, and the silicone-based resin may be mixed in an amount of 10 to 70 wt%, preferably 30 to 70 wt%, more preferably 45 to 70 wt%, and even more preferably 55 to 65 wt%, based on the total weight of the resin composition, and the non-silicone-based resin may be mixed in an amount of 30 to 90 wt%, preferably 30 to 70 wt%, more preferably 30 to 55 wt%, and even more preferably 35 to 45 wt%, based on the total weight of the resin composition. At this time, the silicone-based resin and the non-silicone-based resin are as described above.

[0065] In addition, the release layer formed by curing the composition for forming a release layer may contain silicon (Si) in an amount of 2 to 5 wt%, preferably 3 to 5 wt%, more preferably 3.3 to 5 wt%, and even more preferably 3.8 to 4.9 wt%, based on the total weight%. In addition, the release layer is as described above.

[0066] In addition, the second stage curing can be performed at a temperature of 100 to 140°C, preferably 110 to 130°C, for 10 to 40 seconds, preferably 15 to 25 seconds. If the curing temperature is lower than 100°C, there may be a problem of non-curing, and if it exceeds 140°C, there may be a problem of thermal deformation occurring in the base film.

[0067] Furthermore, when a lithium transfer release film manufactured through the method for manufacturing a lithium transfer release film of the present invention is formed by depositing lithium on one surface of the release layer to a thickness of 2 to 25 μm, preferably 2 to 20 μm, more preferably 2 to 15 μm, even more preferably 2 to 8 μm, even more preferably 3 to 7 μm, and even more preferably 4 to 6 μm, and then irradiating white light on the base film, 100 or fewer pin holes can be generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

[0068] In addition, the lithium transfer release film manufactured through the method for manufacturing the lithium transfer release film of the present invention may have a surface tension of the release layer of 25 to 30 dyne, preferably 25 to 28 dyne.

[0069] In addition, the lithium transfer release film manufactured through the method for manufacturing the lithium transfer release film of the present invention may have a release force of the release layer of 33 to 44 gf / inch, preferably 33 to 40 gf / inch, and more preferably 34 to 36 gf / inch.

[0070] In addition, the lithium transfer release film manufactured through the method for manufacturing the lithium transfer release film of the present invention may have a water contact angle of the release layer of 95 to 105°, preferably 100 to 105°.

[0071]

[0072] Although the present invention has been described above with reference to embodiments, these are merely examples and are not intended to limit the present invention to the embodiments. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

[0073]

[0074] Preparation Example 1: Preparation of a composition for forming a heteromorphic layer

[0075] A composition for forming a release layer was prepared by mixing 1.5 parts by weight of a catalyst, 1 part by weight of an adhesion promoter, and 900 parts by weight of a solvent with respect to 100 parts by weight of a resin composition. At this time, a mixture of 60 wt% of a silicone-based resin and 40 wt% of a non-silicone-based resin with respect to the total weight% of the resin composition was used, platinum was used as the catalyst, dimethyl epoxide-containing methylvinyl siloxane (Dimethyl, Methylvinyl Siloxane with Epoxide) was used as the adhesion promoter, and toluene was used as the solvent. In addition, an addition-reactive silicone-based resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone-based resin, and a cellulose resin was used as the non-silicone-based resin.

[0076]

[0077] Preparation Example 2: Preparation of a composition for forming a heteromorphic layer

[0078] A composition for forming a heteromorphic layer was prepared in the same manner as in Preparation Example 1. However, unlike Preparation Example 1, a resin composition containing 50 wt% of a silicone-based resin and 50 wt% of a non-silicone-based resin was used, based on the total weight%.

[0079]

[0080] Preparation Example 3: Preparation of a composition for forming a heteromorphic layer

[0081] A composition for forming a heteromorphic layer was prepared in the same manner as in Preparation Example 1. However, unlike Preparation Example 1, a resin composition containing 40 wt% of silicone resin and 60 wt% of non-silicone resin was used, based on the total weight%.

[0082]

[0083] Preparation Example 4: Preparation of a composition for forming a heteromorphic layer

[0084] A composition for forming a heteromorphic layer was prepared in the same manner as in Preparation Example 1. However, unlike Preparation Example 1, a resin composition containing 20 wt% of silicone resin and 80 wt% of non-silicone resin was used, based on the total weight%.

[0085]

[0086] Comparative Preparation Example 1: Preparation of a Composition for Forming a Heterogeneous Layer

[0087] A composition for forming a heteromorphic layer was prepared in the same manner as in Preparation Example 1. However, unlike Preparation Example 1, a resin composition containing 80 wt% of a silicone-based resin and 20 wt% of a non-silicone-based resin was used, based on the total weight%.

[0088]

[0089] Comparative Preparation Example 2: Preparation of a Composition for Forming a Heterogeneous Layer

[0090] A composition for forming a heteromorphic layer was prepared in the same manner as in Preparation Example 1. However, unlike Preparation Example 1, only a silicone-based resin was used as the resin composition.

[0091]

[0092] Comparative Preparation Example 2: Preparation of a Composition for Forming a Heterogeneous Layer

[0093] A composition for forming a release layer was prepared by mixing 1.5 parts by weight of a catalyst, 1 part by weight of an adhesion promoter, and 600 parts by weight of a solvent with respect to 100 parts by weight of a resin composition. At this time, a silicone-based resin was used as the resin composition, platinum was used as the catalyst, dimethyl epoxide-containing methylvinyl siloxane (Dimethyl, Methylvinyl Siloxane with Epoxide) was used as the adhesion promoter, and toluene was used as the solvent. In addition, an addition-reactive silicone-based resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone-based resin.

[0094]

[0095] Example 1: Preparation of a release film for lithium transfer

[0096] (1) A PET (Polyethylene terephthalate) film (XD510P, TAK) with a thickness of 50 μm was prepared as a base film.

[0097] (2) Using a bar coater, the composition for forming a release layer prepared in Preparation Example 1 was applied to one side of the prepared base film, cured at a temperature of 120°C for 20 seconds, and aged at a temperature of 40°C for 2 days to form a release layer having a thickness of 0.1 μm, thereby manufacturing a release film for lithium transfer.

[0098]

[0099] Example 2: Preparation of a release film for lithium transfer

[0100] A lithium transfer release film was manufactured using the same method as in Example 1. However, unlike Example 1, the release layer forming composition manufactured in Preparation Example 2 was used instead of the release layer forming composition manufactured in Preparation Example 1, thereby finally manufacturing a lithium transfer release film.

[0101]

[0102] Example 3: Preparation of a release film for lithium transfer

[0103] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, the release layer forming composition manufactured in Preparation Example 3 was used instead of the release layer forming composition manufactured in Preparation Example 1, thereby finally manufacturing a lithium transfer release film.

[0104]

[0105] Example 4: Preparation of a release film for lithium transfer

[0106] A lithium transfer release film was manufactured using the same method as in Example 1. However, unlike Example 1, the release layer forming composition manufactured in Preparation Example 4 was used instead of the release layer forming composition manufactured in Preparation Example 1, thereby finally manufacturing a lithium transfer release film.

[0107]

[0108] Comparative Example 1: Manufacturing of a release film for lithium transfer

[0109] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, the release layer forming composition manufactured in Comparative Preparation Example 1 was used instead of the release layer forming composition manufactured in Preparation Example 1, thereby finally manufacturing a lithium transfer release film.

[0110]

[0111] Comparative Example 2: Manufacturing of a release film for lithium transfer

[0112] A release film for lithium transfer was manufactured in the same manner as in Example 1. However, unlike Example 1, the release layer forming composition manufactured in Comparative Preparation Example 2 was used instead of the release layer forming composition manufactured in Preparation Example 1, and a release layer having a thickness of 0.15 μm was formed, thereby manufacturing a release film for lithium transfer.

[0113]

[0114]

[0115] Experimental Example 1: Measurement of the number of pin holes

[0116] Lithium was deposited to a thickness of 5 μm on one surface of the release layer of each of the lithium transfer release films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 using a PVD (Physical Vapor Deposition) method. Thereafter, white light was irradiated on the base film of each of the lithium transfer release films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2, and the deposited lithium was observed with the naked eye. The number of pinholes generated per unit area of ​​10 cm x 10 cm is shown in Table 1.

[0117]

[0118] Experimental Example 2: Surface Tension Measurement

[0119] Using a dyne reagent, the surface tension of the release layer of the lithium transfer release film manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 was measured, and the results are shown in Table 1 below. 22 to 40 dyne test ink from Arcotest was used as the dyne test ink.

[0120]

[0121] Experimental Example 3: Measurement of release force

[0122] An acrylic adhesive tape (TESA7475) measuring 25 mm in width x 175 mm in length was attached to the release layers of the lithium transfer release films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2, respectively, and then the release force was measured on the release layers of the lithium transfer release films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2, respectively, based on the Finat-10 evaluation method, and the results are shown in Table 1 below.

[0123]

[0124] Experimental Example 4: Water Contact Angle Measurement

[0125] After dropping 50 uL of distilled water (H2O) on the release layer of the lithium transfer release film manufactured in Examples 1 to 4 and Comparative Examples 1 to 2, the water contact angle on the release layer of the lithium transfer release film manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 was measured using a contact angle measuring device, and the results are shown in Table 1 below.

[0126]

[0127] Experimental Example 5: Measurement of Silicon (Si) Content

[0128] Using a scanning electron microscope (SEM) equipped with EDS (Energy Dispersive X-ray Spectroscopy), the silicon (Si) content contained in each of the lithium transfer films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 was measured, and the results are shown in Table 1 below.

[0129]

[0130] Experimental Example 6: Measurement of Lithium Transfer Efficiency

[0131] Lithium was deposited to a thickness of 5 μm on one surface of the release layer of each of the lithium transfer release films manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 using a PVD (Physical Vapor Deposition) method. Thereafter, the lithium deposited on the lithium transfer release film was roll-laminated onto one surface of a copper foil (Cu foil) used as an anode current collector, and the lithium transfer release film was removed, thereby transferring the lithium to the copper foil. After the transfer, the area of ​​lithium remaining on the lithium transfer release film was visually confirmed, and the lithium transfer efficiency was calculated using the following calculation formula 1, which is shown in Table 1 below.

[0132] [Calculation Formula 1]

[0133] Lithium transfer efficiency (%) = (Area of ​​lithium deposited on the lithium transfer release film - Area of ​​lithium remaining on the lithium transfer release film after transferring the lithium deposited on the lithium transfer release film to the copper foil) / Area of ​​lithium deposited on the lithium transfer release film

[0134]

[0135]

[0136]

[0137] As can be seen in Table 1, the lithium transfer release films manufactured in Examples 1 to 3 not only had a number of pin holes per unit area of ​​10 cm x 10 cm of 100 or less, but also had excellent lithium transfer efficiency.

[0138]

[0139] Experimental Example 7: Measurement of the number of pin holes

[0140] Lithium was deposited on one side of the release layer of the lithium transfer film manufactured in Example 1 using the PVD (Physical Vapor Deposition) method to a thickness of 5 μm, 10 μm, 15 μm, 20 μm, and 30 μm, respectively. Then, white light was irradiated on the base film of each of the lithium transfer release films manufactured in Example 1, on which lithium was deposited to different thicknesses, and the deposited lithium was observed with the naked eye. The number of pinholes generated per unit area of ​​10 cm x 10 cm is shown in Table 2.

[0141]

[0142]

[0143] As can be seen in Table 2, even when lithium was deposited in thicknesses of 5 ㎛, 10 ㎛, 15 ㎛, and 20 ㎛ on one side of the release layer of the lithium transfer release film manufactured in Example 1, it was confirmed that the number of pin holes per unit area of ​​10 cm x 10 cm was 100 or less. However, when lithium was deposited in a thickness of 30 ㎛ on one side of the release layer of the lithium transfer release film manufactured in Example 1, it was confirmed that thermal deformation occurred during the deposition process.

[0144]

[0145] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

[0146]

[0147] [National Research and Development Project Supporting This Invention]

[0148] [Project ID] 1415185120

[0149] [Assignment Number] 20011254

[0150] Ministry of Trade, Industry and Energy

[0151] [Name of Project Management (Specialist) Institution] Korea Institute of Industrial Technology Planning and Evaluation

[0152] [Research Project Name] Material and Component Technology Development (Research and Analysis Project Name: Material and Component Technology Development)

[0153] [Research Project Name] Development of Ultra-Releasable Functional Release-Adhesive Film Technology with Minimal Sequential Change

[0154] [Contribution rate] 1 / 1

[0155] [Name of Project Performing Organization] Yulchon Chemical Co., Ltd.

[0156] [Research Period] January 1, 2023 - December 31, 2023

Claims

1. A lithium transfer release film comprising a base film; and a release layer formed on one surface of the base film; A lithium transfer release film characterized in that when lithium is deposited on one side of the release layer to a thickness of 2 to 25 ㎛ and white light is irradiated on the base film, less than 100 pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

2. In paragraph 1, The above heterogeneous layer comprises a resin composition, A lithium transfer release film, characterized in that the resin composition contains 10 to 70 wt% of a silicone resin based on the total weight%.

3. In paragraph 2, A lithium transfer release film, characterized in that the release layer contains 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.

4. In paragraph 1, A lithium transfer film characterized in that the above-mentioned heterolayer contains 2 to 5 wt% of silicon (Si) based on the total weight%.

5. In paragraph 1, The surface tension of the above heterogeneous layer is 25 to 30 dyne, The release force of the above-mentioned release layer is 33 to 44 gf / inch, A lithium transfer release film, characterized in that the water contact angle of the above release layer is 95 to 105°.

6. In paragraph 1, A lithium transfer release film, characterized in that the base film comprises at least one selected from PET (Polyethylene terephthalate), PP (Polypropylene), PBT (Polybutyleneterephthalate), PEN (Polyethylene naphthalate), PI (Polyimide), and PE (Polyethylene).

7. In paragraph 2, The above resin composition comprises a silicone-based resin and a non-silicon-based resin, The above silicone resin includes at least one selected from addition reaction type silicone resin, condensation reaction type silicone resin and UV reaction type silicone resin. A lithium transfer release film, characterized in that the non-silicon-based resin comprises at least one selected from a cellulose resin, an acrylate-based resin, a melamine-based resin, and an alkyd-based resin.

8. In paragraph 1, A lithium transfer release film characterized in that when lithium is deposited on one side of the release layer to a thickness of 2 to 8 ㎛ and white light is irradiated on the base film, less than 100 pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

9. Step 1: Preparing the base film; and A second step of forming a release layer by applying a composition for forming a release layer to one side of the base film and then curing the composition; including; A method for manufacturing a lithium transfer release film, characterized in that when lithium is deposited on one side of the release layer to a thickness of 2 to 25 μm and white light is irradiated on the base film, 100 or fewer pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

10. In paragraph 9, The composition for forming the above heteromorphic layer is a mixture of a resin composition, a catalyst, an adhesion enhancer, and a solvent. A method for manufacturing a lithium transfer release film, characterized in that the resin composition contains 10 to 70 wt% of a silicone resin based on the total weight%.

11. In paragraph 10, A method for manufacturing a release film for lithium transfer, characterized in that the composition for forming the 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 promoter, and 800 to 1,000 parts by weight of a solvent per 100 parts by weight of a resin composition.

12. In paragraph 9, A method for manufacturing a lithium transfer film, characterized in that the above curing is performed at a temperature of 100 to 140°C for 10 to 40 seconds.

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