KR-102959139-B1 - Method Of Manufacturing Surface-Treated Film For Cell Pouch And Film For Cell Pouch Manufactured Therefrom

KR102959139B1KR 102959139 B1KR102959139 B1KR 102959139B1KR-102959139-B1

Abstract

The present invention provides a method for manufacturing a surface-treated cell pouch film comprising a first resin layer, a metal layer, and a second resin layer, wherein a portion of the second resin layer is subjected to a surface treatment, and the surface treatment is a corona discharge treatment, and a cell pouch film manufactured thereby.

Inventors

송녹정
한희식
이두희
장지은
정종혁
김유한
신성철

Assignees

율촌화학 주식회사

Dates

Publication Date: 20260508
Application Date: 20241230

Claims (19)

A film for a cell pouch comprising a first resin layer, a metal layer, and a second resin layer, Surface treatment is performed on a portion of the second resin layer that serves as the sealing portion of the film for the cell pouch. The second resin layer above comprises non-oriented polypropylene (cPP), and The above surface treatment is a corona discharge treatment, and As the surface tension (dyne) value of the surface-treated portion of the second resin layer increases due to the corona discharge treatment above, the thermal adhesion strength (5 mm/min) of the surface-treated portion of the second resin layer decreases, and A method for manufacturing a surface-treated cell pouch film, wherein the measurement of the above thermal adhesion strength is performed by separating the interface of the second resin layers that are in contact with each other at a 180-degree angle.
In claim 1, A method for manufacturing a surface-treated film for a cell pouch, wherein the discharge amount during the corona discharge treatment is 80W·min/m² to 250W·min/m².
In claim 1, A method for manufacturing a surface-treated film for a cell pouch, wherein the frequency during the corona discharge treatment is 0.1 kHz to 5 kHz.
In claim 1, A method for manufacturing a surface-treated film for a cell pouch, wherein the first resin layer comprises at least one of a polyester resin or a polyamide resin.
In claim 1, A method for manufacturing a surface-treated film for a cell pouch, wherein the metal layer comprises one or more selected from the group consisting of aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), stainless steel (SUS), tin (Sn), zinc (Zn), indium (In), tungsten (W), titanium (Ti), and invar.
In claim 1, A method for manufacturing a surface-treated film for a cell pouch, wherein the second resin layer further comprises one or more selected from the group consisting of polyolefin-based, polybutylene-based, ethylene copolymer, propylene copolymer, polyester-based, polyamide-based, polycarbonate-based, fluorine-based, silicone-based, cyclic polyolefin, carboxylic acid-modified cyclic polyolefin, acrylic-based, ethylene-propylene-diene-monomer rubber (EPDM), and polyolefin ketone copolymer.
In claim 1, A method for manufacturing a surface-treated cell pouch film, wherein a surface treatment area in which the corona discharge treatment is performed is formed in the second resin layer of the cell pouch film, and a pair of surface treatment areas are formed symmetrically with respect to a reference line parallel to the MD direction or a reference line parallel to the TD direction, and a pair of surface treatment areas are formed at regular intervals along the MD direction.
In claim 7, The above surface treatment area is, A first surface treatment area formed on the outer side based on the above reference line and where the corona discharge treatment is performed as a pattern area; and A method for manufacturing a surface-treated cell pouch film, comprising: a second surface treatment area formed on the inner side based on the above reference line and having the corona discharge treatment applied to the entire area.
In claim 1, A method for manufacturing a surface-treated cell pouch film, wherein, during the corona discharge treatment of the second resin layer, a mask is provided between the second resin layer and the corona discharge treatment device.
In claim 8, A method for manufacturing a surface-treated cell pouch film, characterized in that the area of the pattern area of the first surface treatment area is formed to be 30 to 50% of the total area of the first surface treatment area.
In claim 1, A method for manufacturing a surface-treated cell pouch film, wherein the surface tension (dyne) value of the surface-treated portion of the second resin layer is increased by 30 to 65% compared to the surface tension value of the untreated portion of the second resin layer.
In claim 1, A method for manufacturing a surface-treated cell pouch film, wherein the maximum value of the thermal bonding strength (5 mm/min) at 200°C of the surface-treated portion of the second resin layer is reduced by 10 to 35% compared to the maximum value of the thermal bonding strength (5 mm/min) at 200°C of the un-surface-treated portion of the second resin layer.
A film for a cell pouch comprising a first resin layer, a metal layer, and a second resin layer, The second resin layer above comprises non-oriented polypropylene (cPP), and A portion of the second resin layer, which serves as the sealing portion of the film for the cell pouch, is treated with corona discharge, which is a surface treatment. As the surface tension (dyne) value of the surface-treated portion of the second resin layer increases due to the corona discharge treatment above, the thermal adhesion strength (5 mm/min) of the surface-treated portion of the second resin layer decreases, and A film for a cell pouch, wherein the measurement of the above thermal adhesive strength is performed by separating the interface of the second resin layers that are in contact with each other at a 180-degree angle.
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In claim 13, A surface-treated cell pouch film in which the surface tension (dyne) value of the surface-treated portion of the second resin layer is increased by 30 to 65% compared to the surface tension value of the untreated portion of the second resin layer.
In claim 13, A surface-treated cell pouch film, wherein the maximum value of the thermal bonding strength (5 mm/min) at 200°C of the surface-treated portion of the second resin layer is reduced by 10 to 35% compared to the maximum value of the thermal bonding strength (5 mm/min) at 200°C of the un-surface-treated portion of the second resin layer.
In claim 13, A surface-treated cell pouch film having a surface treatment area formed in the second resin layer of the cell pouch film, wherein the surface treatment area is formed symmetrically with respect to a reference line parallel to the MD direction or a reference line parallel to the TD direction, and a pair of surface treatment areas are formed at regular intervals along the MD direction.
In claim 17, The above surface treatment area is, A first surface treatment area formed on the outer side based on the above reference line and where the corona discharge treatment is performed as a pattern area; and A surface-treated film for a cell pouch, comprising: a second surface treatment area formed on the inner side based on the above reference line and having the corona discharge treatment applied to the entire area.
In claim 18, A surface-treated cell pouch film characterized in that the area of the pattern area of the first surface treatment area is formed to be 30 to 50% of the total area of the first surface treatment area.

Description

Method of Manufacturing Surface-Treated Film for Cell Pouch and Film for Cell Pouch Manufactured Therefrom The present invention relates to a method for manufacturing a surface-treated film for a cell pouch and a film for a cell pouch manufactured therefrom. Pouch-type lithium secondary batteries have a structure in which electrodes and an electrolyte are sealed inside a pouch made of a thin, flexible plastic film and a metal foil. This structure is widely used in various devices such as electric vehicles, smartphones, and laptops because it has the advantages of being lightweight, having high energy density, and being designable in various shapes. However, pouch-type lithium secondary batteries undergo 'swelling,' a phenomenon of expansion and contraction caused by internal gas generation during the charging and discharging process. If this swelling is not properly managed, it can put a strain on the battery's physical structure and cause safety issues. To address these issues, vent systems have been introduced in pouch-type lithium secondary batteries. Conventional vent systems are primarily located in the sealing portion of the pouch and operate by releasing gas when the internal pressure exceeds a certain level. In pouch-type lithium secondary batteries, the sealant layer plays an important role in preventing electrolyte leakage and protecting the inside of the battery from the external environment. Previously, polyolefin-based materials such as polyethylene or polypropylene were mainly used as sealant layers. However, these single-layer sealant layers have several limitations. Due to insufficient water permeability, moisture can react with the electrolyte to produce hydrofluoric acid (HF), which can lead to corrosion and performance degradation of the battery. Additionally, the sealant layer may deteriorate during long-term use due to insufficient resistance to chemicals contained in the electrolyte. Furthermore, the physical properties of the sealant layer may change in high-temperature environments, potentially degrading sealing performance. To overcome the limitations of existing technology and improve the safety and performance of pouch-type lithium secondary batteries, a new approach to the sealant layer has become necessary. In particular, there is a demand for technology that can simultaneously improve water permeability, chemical resistance, and heat resistance while ensuring venting characteristics. Surface treatment technology for sealant layers is attracting attention as a promising method to meet these requirements. Various studies are being conducted to improve the physical and chemical properties of sealant layers through surface treatment. FIG. 1 is a cross-sectional view of a film for a cell pouch according to an embodiment of the present invention; FIG. 2 is an example diagram of a corona treatment process for a film for a cell pouch according to an embodiment of the present invention; FIGS. 3 and 4 are exemplary diagrams showing a surface treatment area in a film for a cell pouch according to an embodiment of the present invention; and FIG. 5 is an enlarged view of the surface treatment area of a film for a cell pouch according to an embodiment of the present invention. Hereinafter, various embodiments of the present invention are described with reference to the accompanying drawings. The present invention is not limited to specific embodiments and should be understood to include various modifications, equivalents, and/or alternatives of the embodiments of the present invention. In relation to the description of the drawings, similar reference numerals may be used for similar components. In this document, expressions such as "have," "can have," "include," or "can include" refer to the existence of the relevant feature (e.g., numerical values, functions, actions, or components, etc.) and do not exclude the existence of additional features. In this document, expressions such as “A or B,” “at least one of A or/and B,” or “one or more of A or/and B” may include all possible combinations of items listed together. For example, “A or B,” “at least one of A and B,” or “at least one of A or B” may refer to cases including (1) at least one A, (2) at least one B, or (3) both at least one A and at least one B. As used in this document, the expression "configured to" may be replaced, depending on the context, with, for example, "suitable for," "having the capacity to," "designed to," "adapted to," "made to," or "capable of." The term "configured to" does not necessarily mean "specifically designed to." The terms used in this document are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this doc