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 secure 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] In addition, for convenience of use, a plurality of lithium transfer release films of the present invention are laminated, and when separated again, not only is the release film excellent in unraveling properties, but also the lithium transfer release film can prevent the phenomenon of lithium (Li) being transferred to a part other than the part where lithium (Li) is deposited, and a method for manufacturing the same are provided.

[0011]

[0012] In order to solve the above-described problem, the lithium transfer film of the present invention may have a structure in which a first release layer, a base film, and a second release layer are sequentially laminated.

[0013] In a preferred embodiment of the present invention, the lithium transfer film of the present invention can satisfy the following condition (1).

[0014] (1) A < B

[0015] In the above condition (1), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0016] In a preferred embodiment of the present invention, the lithium transfer film of the present invention can further satisfy the following condition (2).

[0017] (2) A:B = 1:1.1 ~ 5.0

[0018] In the above condition (2), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0019] In a preferred embodiment of the present invention, the base film and the first release layer may have a thickness ratio of 1:0.0014 to 0.0026.

[0020] In a preferred embodiment of the present invention, the base film and the second release layer may have a thickness ratio of 1:0.001 to 0.0018.

[0021] In a preferred embodiment of the present invention, when lithium is deposited on one surface of a second release layer of a lithium transfer release film of the present invention to a thickness of 2 to 25 μm and white light is irradiated on the first release layer, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0022] In a preferred embodiment of the present invention, when lithium is deposited on one surface of a second release layer of a lithium transfer release film of the present invention to a thickness of 2 to 8 μm and white light is irradiated on the first release layer, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0023] In a preferred embodiment of the present invention, the second heterogeneous layer may include a resin composition.

[0024] 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%.

[0025] In a preferred embodiment of the present invention, the second 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, based on 100 parts by weight of the resin composition.

[0026] In a preferred embodiment of the present invention, the first heterogeneous layer may contain 2.2 to 25 wt% of silicon (Si) based on the total wt%.

[0027] In a preferred embodiment of the present invention, the second heterogeneous layer may contain 2 to 5 wt% of silicon (Si) based on the total wt%.

[0028] 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).

[0029] In a preferred embodiment of the present invention, the resin composition may include a silicone-based resin and a non-silicone-based resin.

[0030] 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.

[0031] 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.

[0032] Meanwhile, the method for manufacturing a lithium transfer 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 first release layer to one side of the base film, applying a composition for forming a second release layer to the other side of the base film, and then curing the same to form a first release layer on one side of the base film and a second release layer on the other side of the base film, and can satisfy the following condition (1).

[0033] (1) A < B

[0034] In the above condition (1), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0035] In a preferred embodiment of the present invention, the method for manufacturing a lithium transfer film of the present invention can further satisfy the following condition (2).

[0036] (2) A:B = 1:1.1 ~ 5.0

[0037] In the above condition (2), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0038] In a preferred embodiment of the present invention, when lithium is deposited on one surface of the second release layer to a thickness of 2 to 25 μm and white light is irradiated on the first release layer, 100 or fewer pin holes per unit area of ​​10 cm x 10 cm can be generated in the deposited lithium.

[0039] In a preferred embodiment of the present invention, the composition for forming the second heterogeneous layer may be a mixture of a resin composition, a catalyst, an adhesion enhancer, and a solvent.

[0040] 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%.

[0041] In a preferred embodiment of the present invention, the composition for forming the second 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.

[0042] 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.

[0043]

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In addition, the lithium transfer release film of the present invention and the method for manufacturing the same are excellent in unraveling properties even when a plurality of lithium transfer release films of the present invention are laminated for convenience of use and separated again.

[0048] In addition, the lithium transfer release film of the present invention and the method for manufacturing the same can prevent the phenomenon of lithium (Li) being transferred to a part other than the part where lithium (Li) is deposited when a plurality of lithium transfer release films of the present invention are laminated for convenience of use and separated again.

[0049]

[0050] FIG. 1 is a cross-sectional view showing a lithium transfer film on one side according to a preferred embodiment of the present invention.

[0051] FIG. 2 is a schematic diagram showing the process of depositing lithium on one surface of a second release layer according to a preferred embodiment of the present invention, and then observing the occurrence of pin holes in the deposited lithium by irradiating white light on the first release layer.

[0052]

[0053] 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.

[0054]

[0055] Referring to FIG. 1, the lithium transfer film of the present invention may have a structure in which a first release layer (10), a base film (20), and a second release layer (30) are sequentially laminated.

[0056] The first release layer (10) is a film that not only improves the release property but also prevents lithium that may be deposited on the second release layer (30) from being transferred to the opposite surface, and may include a silicone resin, preferably 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.

[0057] In addition, the first release layer (10) may have a thickness of 0.05 to 5 ㎛, preferably a thickness of 0.1 to 1 ㎛, and more preferably a thickness of 0.1 to 0.3 ㎛. If the thickness is less than 0.05 ㎛, there may be a problem of increased release force, and if it exceeds 5 ㎛, there may be a problem of blocking occurring.

[0058] In addition, the first release layer (10) may contain silicon (Si) in an amount of 2.2 to 25 wt%, preferably 3 to 20 wt%, more preferably 5 to 15 wt%, and even more preferably 10 to 15 wt%, based on the total weight%. If the silicon is contained in an amount less than 2.2 wt%, there may be a problem of a decrease in the lithium transfer prevention effect due to an increase in release force, and if it is contained in an amount exceeding 25 wt%, there may be a problem of the silicon (Si) component of the first release layer (10) being transferred to lithium that may be deposited on the second release layer (30).

[0059] In addition, the first release layer (10) may contain 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, with respect to 100 parts by weight of a silicone resin. 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 the release force increasing beyond an appropriate level.

[0060] Additionally, any catalyst commonly used in the art may be used as the catalyst, and preferably may include platinum.

[0061] Furthermore, the first release layer (10) 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 a silicone resin. 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 first release layer (10) and the base film (20), and if it exceeds 5 parts by weight, there may be a problem of silicon (Si) contained in the first release layer (10) being transferred to the back surface of the base film (20) (the surface on which the second release layer is formed).

[0062] The adhesion enhancer is a material that plays a role in improving the adhesion between the first release layer (10) and the base film (20). Any adhesion enhancer commonly used in the art can be used, and preferably, it can include methylvinyl siloxane with dimethyl epoxide.

[0063] The base film (20) not only serves as a substrate for forming the first release layer (10) and the second release layer (30), but also serves as a substrate for enabling uniform lithium deposition on the second release layer (30) and / or serves as a support for transferring lithium that can be deposited on the second release layer (30) to a current collector. Any material used in the art for the base film may be used, and preferably, it may include at least one selected from PET (Polyethylene terephthalate), PP (Polypropylene), PBT (Polybutylene terephthalate), PEN (Polyethylene naphthalate), PI (Polyimide), and PE (Polyethylene), and more preferably, it may include PET.

[0064] In addition, the base film (20) 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 (20) during a lithium (Li) deposition process performed at high temperature, and if it exceeds 250 ㎛, there may be a problem of economic feasibility.

[0065] The second heterogeneous layer (30) is a layer that uniformly deposits lithium (Li) or smoothly transfers lithium (Li) to the current collector, and is a layer on which lithium is deposited on one side to transfer lithium.

[0066] The second heterogeneous layer (30) may have a thickness of 0.01 to 1 ㎛, preferably 0.05 to 0.5 ㎛, and more preferably 0.05 to 0.3 ㎛. 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 occurring during winding.

[0067] Meanwhile, the base film (20) and the first release layer (10) may have a thickness ratio of 1:0.0014 to 0.0026, preferably 1:0.0016 to 0.0024.

[0068] Additionally, the base film (20) and the second release layer (30) may have a thickness ratio of 1:0.001 to 0.0018, preferably 1:0.0011 to 0.0016.

[0069] The second release layer (30) 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 second release layer.

[0070] 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.

[0071] 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.

[0072] 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 resin, acrylate resin, melamine resin, and alkyd resin, and preferably may include cellulose resin.

[0073] In addition, the second release layer (30) 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 the 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 second release layer.

[0074] Furthermore, the second release layer (30) 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 the peeling force increasing above a certain level.

[0075] Additionally, any catalyst commonly used in the art may be used as the catalyst, and preferably may include platinum.

[0076] Furthermore, the second release layer (30) 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 second release layer (30) and the base film (20), and if it exceeds 5 parts by weight, there may be a problem of silicon (Si) contained in the second release layer (30) being transferred to the back surface of the base film (20) (the surface on which the first release layer is formed).

[0077] The adhesion enhancer is a material that plays a role in improving the adhesion between the second release layer (10) and the base film (20). Any adhesion enhancer commonly used in the art can be used, and preferably, it can include methylvinyl siloxane with dimethyl epoxide.

[0078]

[0079] Meanwhile, the lithium transfer film of the present invention can satisfy the following condition (1).

[0080] (1) A < B

[0081] In the above condition (1), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0082] If condition (1) is not satisfied, there may be a problem of lithium deposited in the second heterostructure layer being transferred to the first heterostructure layer.

[0083] In addition, the lithium transfer film of the present invention can further satisfy the following condition (2).

[0084] (2) A: B = 1: 1.1 ~ 5.0, preferably A: B = 1: 1.5 ~ 5.0, more preferably A: B = 1: 2.5 ~ 5.0, even more preferably A: B = 1: 3.5 ~ 4.5

[0085] In the above condition (2), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0086] If A and B are less than 1:1.1, there may be a problem that lithium that can be deposited on the second release layer is transferred to the first release layer, and if it exceeds 1:5.0, the silicon (Si) content of the first release layer may increase, and the increased silicon (Si) content may cause a problem that silicon (Si) is transferred to the lithium surface that can be deposited on the second release layer.

[0087]

[0088] Furthermore, referring to FIG. 2, in the lithium transfer release film of the present invention, lithium (40) is deposited on one surface of the second release layer (30) to a thickness of 2 to 25 μm, preferably 2 to 20 μm, more preferably 2 to 15 μm, still more preferably 2 to 8 μm, still more preferably 3 to 7 μm, and still more preferably 4 to 6 μm, and then when white light is irradiated on the second release layer (10), 100 or fewer pin holes per unit area of ​​10 cm x 10 cm may be generated in the deposited lithium (40). Pin holes refer to pores generated in the lithium (40) during deposition. If more than 100 pin holes per unit area of ​​10 cm x 10 cm are generated in the lithium (40), there may be a problem that the lithium (40) is not deposited uniformly. Also, white light refers to light with a wavelength of 400 to 700 nm.

[0089]

[0090] Meanwhile, the method for manufacturing a lithium transfer film of the present invention includes a first step and a second step.

[0091] First, in the first step of the method for manufacturing a lithium transfer film of the present invention, a base film may be prepared. At this time, the base film is as described above.

[0092] Next, in the second step of the method for manufacturing a lithium transfer film of the present invention, a composition for forming a first release layer is applied to one side of the base film prepared in the first step, a composition for forming a second release layer is applied to the other side of the base film, and then cured to form a first release layer on one side of the base film and a second release layer on the other side of the base film.

[0093] The composition for forming the first release layer may be a mixture of a silicone resin, a catalyst, an adhesion promoter, and a solvent. Specifically, the composition for forming the first 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 an adhesion promoter, preferably 0.5 to 3.0 parts by weight, and more preferably 0.5 to 1.5 parts by weight, and 500 to 5,000 parts by weight of a solvent, preferably 550 to 4,000 parts by weight, per 100 parts by weight of a silicone resin. 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).

[0094] In addition, the first release layer formed by curing the composition for forming the first release layer may contain silicon (Si) in an amount of 2.2 to 25 wt%, preferably 3 to 20 wt%, more preferably 5 to 15 wt%, and even more preferably 10 to 15 wt%, based on the total weight%. In addition, the first release layer is as described above.

[0095] The composition for forming the second release layer may be a mixture of a resin composition, a catalyst, an adhesion promoter, and a solvent. Specifically, the composition for forming the second 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 an 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, based on 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).

[0096] 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.

[0097] In addition, the second release layer formed by curing the composition for forming the second 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 second release layer is as described above.

[0098] 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.

[0099] 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 a second 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 first release layer, 100 or fewer pin holes can be generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

[0100] In addition, a lithium transfer release film manufactured through the method for manufacturing a lithium transfer release film of the present invention can satisfy the following condition (1).

[0101] (1) A < B

[0102] In the above condition (1), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0103] In addition, a lithium transfer release film manufactured through the method for manufacturing a lithium transfer release film of the present invention can further satisfy the following condition (2).

[0104] (2) A: B = 1: 1.1 ~ 5.0, preferably A: B = 1: 1.5 ~ 5.0, more preferably A: B = 1: 2.5 ~ 5.0, even more preferably A: B = 1: 3.5 ~ 4.5

[0105] In the above condition (2), A represents the release force of the first release layer, and B represents the release force of the second release layer.

[0106]

[0107] 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.

[0108]

[0109] Preparation Example 1-1: Preparation of a composition for forming a first heterogeneous layer

[0110] A composition for forming a first 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 silicone resin. At this time, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin, platinum was used as the catalyst, dimethyl, methylvinyl siloxane with epoxide was used as the adhesion promoter, and toluene was used as the solvent.

[0111]

[0112] Preparation Example 1-2: Preparation of a composition for forming a first heterogeneous layer

[0113] A composition for forming a first release layer was prepared by mixing 1.5 parts by weight of a catalyst, 1 part by weight of an adhesion promoter, and 1,100 parts by weight of a solvent with respect to 100 parts by weight of a silicone resin. At this time, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin, platinum was used as the catalyst, dimethyl, methylvinyl siloxane with epoxide was used as the adhesion promoter, and toluene was used as the solvent.

[0114]

[0115] Preparation Example 1-3: Preparation of a composition for forming a first heterogeneous layer

[0116] A composition for forming a first release layer was prepared by mixing 1.5 parts by weight of a catalyst, 1 part by weight of an adhesion promoter, and 3,500 parts by weight of a solvent with respect to 100 parts by weight of a silicone resin. At this time, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin, platinum was used as the catalyst, dimethyl, methylvinyl siloxane with epoxide was used as the adhesion promoter, and toluene was used as the solvent.

[0117]

[0118] Preparation Example 1-4: Preparation of a composition for forming a first heterogeneous layer

[0119] A composition for forming a first 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 mixed composition. At this time, a mixture of 80 wt% of a silicone resin and 20 wt% of dimethylvinylated and trimethylated silica (CAS Reg. No. 68988-89-6) with respect to the total weight% of the mixed composition was used, platinum was used as a catalyst, dimethyl, methylvinyl siloxane with epoxide was used as an adhesion promoter, and toluene was used as a solvent. In addition, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin.

[0120]

[0121] Preparation Example 1-5: Preparation of a composition for forming a first heterogeneous layer

[0122] A composition for forming a first 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 mixed composition. At this time, a mixture of 78 wt% of a silicone resin and 22 wt% of dimethylvinylated and trimethylated silica (CAS Reg. No. 68988-89-6) with respect to the total weight% of the mixed composition was used, platinum was used as a catalyst, dimethyl, methylvinyl siloxane with epoxide was used as an adhesion promoter, and toluene was used as a solvent. In addition, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin.

[0123]

[0124] Preparation Example 1-6: Preparation of a composition for forming a first heteromorphic layer

[0125] A composition for forming a first 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 mixed composition. At this time, a mixture of 70 wt% of a silicone resin and 30 wt% of dimethylvinylated and trimethylated silica (CAS Reg. No. 68988-89-6) with respect to the total weight% of the mixed composition was used, platinum was used as a catalyst, dimethyl, methylvinyl siloxane with epoxide was used as an adhesion promoter, and toluene was used as a solvent. In addition, an addition-reactive silicone resin (Dimethyl, 5-hexenylmethyl siloxane) was used as the silicone resin.

[0126]

[0127] Preparation Example 2-1: Preparation of a composition for forming a second heterogeneous layer

[0128] A composition for forming a second 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, 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.

[0129]

[0130] Preparation Example 2-2: Preparation of a composition for forming a second heterogeneous layer

[0131] A composition for forming a second heterogeneous layer was prepared in the same manner as in Preparation Example 2-1. However, unlike Preparation Example 2-1, 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 percentage.

[0132]

[0133] Preparation Example 2-3: Preparation of a composition for forming a second heterogeneous layer

[0134] A composition for forming a second heterogeneous layer was prepared in the same manner as in Preparation Example 2-1. However, unlike Preparation Example 2-1, a resin composition containing 40 wt% of a silicone-based resin and 60 wt% of a non-silicone-based resin was used, based on the total weight%.

[0135]

[0136] Preparation Example 2-4: Preparation of a composition for forming a second heterogeneous layer

[0137] A composition for forming a second heterogeneous layer was prepared in the same manner as in Preparation Example 2-1. However, unlike Preparation Example 2-1, a resin composition containing 20 wt% of a silicone-based resin and 80 wt% of a non-silicone-based resin was used, based on the total weight%.

[0138]

[0139] Preparation Example 2-5: Preparation of a composition for forming a second heterogeneous layer

[0140] A composition for forming a second heterogeneous layer was prepared in the same manner as in Preparation Example 2-1. However, unlike Preparation Example 2-1, 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%.

[0141]

[0142] Preparation Example 2-6: Preparation of a composition for forming a second heterogeneous layer

[0143] A composition for forming a second heterogeneous layer was prepared in the same manner as in Preparation Example 2-1. However, unlike Preparation Example 2-1, only a silicone-based resin was used as the resin composition.

[0144]

[0145] Example 1: Preparation of a release film for lithium transfer

[0146] (1) A PET (Polyethylene terephthalate) film (XD510P, TAK) with a thickness of 75㎛ was prepared as a base film.

[0147] (2) Using a bar coater, the first release layer forming composition manufactured in Preparation Example 1-1 was applied to one side of the prepared base film, and the second release layer forming composition manufactured in Preparation Example 2-1 was applied to the other side of the base film, and then cured at a temperature of 120°C for 20 seconds and aged at a temperature of 40°C for 2 days, thereby forming a first release layer having a thickness of 0.15 μm on one side of the base film and forming a second release layer having a thickness of 0.1 μm on the other side of the base film, thereby manufacturing a release film for lithium transfer.

[0148]

[0149] Example 2: Preparation of a release film for lithium transfer

[0150] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a first release layer forming composition manufactured in Preparation Example 1-2 was used instead of the first release layer forming composition manufactured in Preparation Example 1-1, thereby forming a first release layer having a thickness of 0.08 μm, thereby finally manufacturing a lithium transfer release film.

[0151]

[0152] Example 3: Preparation of a release film for lithium transfer

[0153] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a first release layer forming composition manufactured in Preparation Example 1-3 was used instead of the first release layer forming composition manufactured in Preparation Example 1-1, thereby forming a first release layer having a thickness of 0.025 μm, thereby finally manufacturing a lithium transfer release film.

[0154]

[0155] Example 4: Preparation of a release film for lithium transfer

[0156] A lithium transfer release film was manufactured in the same manner as in Example 1. However, unlike Example 1, a first release layer-forming composition manufactured in Preparation Example 1-4 was used instead of the first release layer-forming composition manufactured in Preparation Example 1-1 to form a first release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0157]

[0158] Comparative Example 1: Manufacturing of a release film for lithium transfer

[0159] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a first release layer-forming composition manufactured in Preparation Example 1-5 was used instead of the first release layer-forming composition manufactured in Preparation Example 1-1 to form a first release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0160]

[0161] Comparative Example 2: Manufacturing of a release film for lithium transfer

[0162] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a first release layer-forming composition manufactured in Preparation Example 1-6 was used instead of the first release layer-forming composition manufactured in Preparation Example 1-1 to form a first release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0163]

[0164] Example 5: Preparation of a release film for lithium transfer

[0165] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a second release layer-forming composition manufactured in Preparation Example 2-2 was used instead of the second release layer-forming composition manufactured in Preparation Example 2-1 to form a second release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0166]

[0167] Example 6: Preparation of a release film for lithium transfer

[0168] A lithium transfer release film was manufactured in the same manner as in Example 1. However, unlike Example 1, a second release layer-forming composition manufactured in Preparation Example 2-3 was used instead of the second release layer-forming composition manufactured in Preparation Example 2-1 to form a second release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0169]

[0170] Example 7: Preparation of a release film for lithium transfer

[0171] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a second release layer-forming composition manufactured in Preparation Example 2-4 was used instead of the second release layer-forming composition manufactured in Preparation Example 2-1 to form a second release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0172]

[0173] Example 8: Preparation of a release film for lithium transfer

[0174] A lithium transfer release film was manufactured in the same manner as in Example 1. However, unlike Example 1, a second release layer-forming composition manufactured in Preparation Example 2-5 was used instead of the second release layer-forming composition manufactured in Preparation Example 2-1 to form a second release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0175]

[0176] Example 9: Preparation of a release film for lithium transfer

[0177] A lithium transfer release film was manufactured using the same method as Example 1. However, unlike Example 1, a second release layer forming composition manufactured in Preparation Example 2-6 was used instead of the second release layer forming composition manufactured in Preparation Example 2-1 to form a second release layer having a thickness of 0.1 μm, thereby finally manufacturing a lithium transfer release film.

[0178]

[0179] Experimental Example 1: Evaluation of the dissolution and whether lithium was transferred to the first heterostructure layer.

[0180] Lithium was deposited to a thickness of 5 μm on one side of the release layer of each of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2 using the PVD (Physical Vapor Deposition) method. Two sheets of the lithium transfer release films on which lithium was deposited were laminated, and 2 kg / cm 2 After a weight having a load was laminated on the lithium formed on the surface of a lithium transfer release film, it was left at a temperature of 40℃ for 2 days. After that, when the two laminated lithium transfer release films on which lithium was deposited were separated, if no sticky sound was generated at all, ◎ was evaluated as such, if only a very small sticky sound was generated, ○ was evaluated as such, and if a loud sticky sound was generated, × was evaluated as such for the looseness, which is shown in Table 1 below. In addition, after the looseness evaluation, it was checked whether lithium was transferred to the first release layer of the separated lithium transfer release film, and if lithium was not generated, ○ was evaluated as such, and if lithium was generated, × was evaluated as such for whether lithium was transferred to the first release layer, which is shown in Table 1 below.

[0181]

[0182] Experimental Example 2: Measurement of the number of pin holes

[0183] Lithium was deposited to a thickness of 5 μm on one side of the second release layer of each of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2 using a PVD (Physical Vapor Deposition) method. Thereafter, white light was irradiated onto the first release layer of each of the lithium transfer release films manufactured in Examples 1 to 9 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.

[0184]

[0185] Experimental Example 3-1: Measurement of the release force of the first release layer

[0186] An acrylic adhesive tape (TESA7475) measuring 25 mm in width x 175 mm in length was attached to the first release layer of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2, respectively, and then the release force of the first release layer of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2 was measured according to the Finat-10 evaluation method, and the results are shown in Table 1 below.

[0187]

[0188] Experimental Example 3-2: Measurement of the release force of the second release layer

[0189] An acrylic adhesive tape (TESA7475) measuring 25 mm in width x 175 mm in length was attached to the second release layer of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2, respectively, and then the release force of the second release layer of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2 was measured according to the Finat-10 evaluation method, and the results are shown in Table 1 below.

[0190]

[0191] Experimental Example 4: Measurement of Silicon (Si) Content

[0192] Using a scanning electron microscope (SEM) equipped with EDS (Energy Dispersive X-ray Spectroscopy), the silicon (Si) content included in each of the first release layer and the second release layer of the lithium transfer release films manufactured in Examples 1 to 9 and Comparative Examples 1 to 2 was measured, and the results are shown in Table 1 below.

[0193]

[0194] Experimental Example 5: Measurement of Lithium Transfer Efficiency

[0195] Lithium was deposited to a thickness of 5 μm on one side of the second release layer of each of the lithium transfer release films manufactured in Examples 1 to 9 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 side 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.

[0196] [Calculation Formula 1]

[0197] 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

[0198]

[0199]

[0200]

[0201]

[0202] As can be seen in Tables 1 and 2, the lithium transfer release films manufactured in Examples 1 to 6 not only had excellent release properties, but also showed that lithium was not transferred to the first release layer, the number of pin holes was 100 or less, and the lithium transfer efficiency was excellent.

[0203]

[0204] Experimental Example 6: Measurement of the number of pin holes

[0205] Lithium was deposited on one side of the second release layer of the lithium transfer release film manufactured in Example 1 using a 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 first release layer of each of the lithium transfer release films manufactured in Example 1, each of which had lithium deposited at 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 3.

[0206]

[0207]

[0208]

[0209] As can be seen in Table 3, even when lithium was deposited on one side of the second release layer of the lithium transfer release film manufactured in Example 1 in thicknesses of 5 µm, 10 µm, 15 µm, and 20 µm, 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 on one side of the second release layer of the lithium transfer release film manufactured in Example 1 in a thickness of 30 µm, it was confirmed that thermal deformation occurred during the deposition process.

[0210]

[0211] 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.

[0212]

[0213] [National Research and Development Project Supporting This Invention]

[0214] [Project ID] 1415185120

[0215] [Assignment Number] 20011254

[0216] Ministry of Trade, Industry and Energy

[0217] [Name of Project Management (Specialist) Institution] Korea Institute of Industrial Technology Planning and Evaluation

[0218] [Research Project Name] Material and Component Technology Development (Research and Analysis Project Name: Material and Component Technology Development)

[0219] [Research Project Name] Development of Ultra-Releasable Functional Release-Adhesive Film Technology with Minimal Sequential Change

[0220] [Contribution rate] 1 / 1

[0221] [Name of Project Performing Organization] Yulchon Chemical Co., Ltd.

[0222] [Research Period] January 1, 2023 - December 31, 2023

Claims

1. A lithium transfer release film in which a first release layer; a base film; and a second release layer are sequentially laminated, A lithium transfer film characterized by satisfying the following condition (1). (1) A < B In the above condition (1), A represents the release force of the first heteromorphic layer, and B represents the release force of the second heteromorphic layer.

2. In paragraph 1, A lithium transfer film characterized by further satisfying the following condition (2). (2) A:B = 1:1.1 ~ 5.0 In the above condition (2), A represents the release force of the first heteromorphic layer, and B represents the release force of the second heteromorphic layer.

3. In paragraph 1, A lithium transfer release film characterized in that when lithium is deposited on one surface of the second release layer to a thickness of 2 to 25 μm and white light is irradiated on the first release layer, 100 or fewer pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

4. In paragraph 3, A lithium transfer release film characterized in that when lithium is deposited on one surface of the second release layer to a thickness of 2 to 8 ㎛ and white light is irradiated on the first release layer, less than 100 pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

5. In paragraph 1, The second 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%.

6. In paragraph 5, A lithium transfer release film, characterized in that the second 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.

7. In paragraph 1, The above first heterogeneous layer contains silicon (Si) in an amount of 2.2 to 25 wt% based on the total weight%, A lithium transfer film characterized in that the second heterogeneous layer contains 2 to 5 wt% of silicon (Si) based on the total weight%.

8. 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).

9. In paragraph 5, 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.

10. Step 1: Preparing the base film; and A second step of applying a composition for forming a first release layer to one side of the base film, applying a composition for forming a second release layer to the other side of the base film, and then curing the composition to form a first release layer on one side of the base film and a second release layer on the other side of the base film; including; A method for manufacturing a lithium transfer film, characterized in that it satisfies the following condition (1). (1) A < B In the above condition (1), A represents the release force of the first heteromorphic layer, and B represents the release force of the second heteromorphic layer.

11. In paragraph 10, A method for manufacturing a lithium transfer film, characterized in that the following condition (2) is further satisfied. (1) A : B = 1 : 1.1 ~ 5.0 In the above condition (2), A represents the release force of the first heteromorphic layer, and B represents the release force of the second heteromorphic layer.

12. In paragraph 10, A method for manufacturing a lithium transfer release film, characterized in that when lithium is deposited on one surface of the second release layer to a thickness of 2 to 25 μm and white light is irradiated on the first release layer, 100 or fewer pin holes are generated per unit area of ​​10 cm x 10 cm in the deposited lithium.

13. In paragraph 10, The composition for forming the second heterogeneous 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%.

14. In paragraph 13, A method for manufacturing a release film for lithium transfer, characterized in that the composition for forming the second 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 1,000 parts by weight of a solvent per 100 parts by weight of a resin composition.

15. In paragraph 10, 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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