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US-12620655-B2 - Pouch film laminate, pouch type battery case, and pouch type secondary battery

US12620655B2US 12620655 B2US12620655 B2US 12620655B2US-12620655-B2

Abstract

A pouch film laminate for preparing a pouch type battery case accommodating an electrode assembly is provided. The pouch film laminate includes a sealant layer formed of a first polymer as an innermost layer, a surface protection layer formed of a second polymer as an outermost layer, an aluminum alloy thin film having a grain size of 10 μm to 13 μm, and a gas barrier layer laminated between the surface protection layer and the sealant layer, wherein the gas barrier layer has a thickness of 50 μm to 70 μm, and the sealant layer has a thickness of 70 μm to 100 μm.

Inventors

  • Sang Hun Kim
  • Min Hyeong KANG
  • Hyung Kyun YU
  • Soo Ji HWANG

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260505
Application Date
20210608
Priority Date
20200609

Claims (17)

  1. 1 . A pouch film laminate comprising: a sealant layer formed of a first polymer as an innermost layer; a surface protection layer formed of a second polymer as an outermost layer; a gas barrier layer laminated between the surface protection layer and the sealant layer; and a drawing assistance layer formed of a third polymer and laminated between the surface protection layer and the gas barrier layer, wherein the gas barrier layer has a thickness of 50 μm to 70 μm, wherein the gas barrier layer comprises an aluminum alloy thin film, wherein the sealant layer has a thickness of 70 μm to 100 μm, and wherein a thickness ratio of the drawing assistance layer to the gas barrier layer is in a range of 1:1.5 to 1:2.5.
  2. 2 . The pouch film laminate of claim 1 , wherein the aluminum alloy thin film has alloy number AA8021.
  3. 3 . The pouch film laminate of claim 1 , wherein the aluminum alloy thin film comprises iron in an amount of 1.3 wt % to 1.7 wt %.
  4. 4 . The pouch film laminate of claim 1 , wherein the aluminum alloy thin film comprises silicon in an amount of 0.2 wt % or less.
  5. 5 . The pouch film laminate of claim 1 , wherein the gas barrier layer has a thickness of 55 μm to 65 μm.
  6. 6 . The pouch film laminate of claim 1 , wherein the sealant layer has a thickness of 75 μm to 85 μm.
  7. 7 . The pouch film laminate of claim 1 , wherein the first polymer comprises polypropylene (PP).
  8. 8 . The pouch film laminate of claim 1 , wherein the surface protection layer has a thickness of 5 μm to 25 μm.
  9. 9 . The pouch film laminate of claim 1 , wherein the surface protection layer has a thickness of 7 μm to 12 μm.
  10. 10 . The pouch film laminate of claim 1 , wherein the second polymer comprises polyethylene terephthalate (PET).
  11. 11 . The pouch film laminate of claim 1 , wherein the drawing assistance layer has a thickness of 20 μm to 50 μm.
  12. 12 . The pouch film laminate of claim 11 , wherein the third polymer comprises Nylon.
  13. 13 . The pouch film laminate of claim 1 , wherein the drawing assistance layer has a thickness of 25 μm to 38 μm.
  14. 14 . The pouch film laminate of claim 1 , wherein the pouch film laminate has a total thickness of 160 μm to 200 μm.
  15. 15 . The pouch film laminate of claim 1 , wherein the pouch film laminate has a tensile strength, which is measured while the pouch film laminate is pulled at a tensile speed of 50 mm/min after being cut to a size of 15 mm×80 mm, of 200 N/15 mm to 300 N/15 mm, and has an elongation of 120% to 150%.
  16. 16 . A pouch type battery case accommodating an electrode assembly and being prepared by forming a pouch film laminate, wherein the pouch film laminate comprises: a sealant layer formed of a first polymer as an innermost layer; a surface protection layer formed of a second polymer as an outermost layer; a gas barrier layer laminated between the surface protection layer and the sealant layer; and a drawing assistance layer formed of a third polymer and laminated between the surface protection layer and the gas barrier layer, wherein the gas barrier layer has a thickness of 50 μm to 70 μm, wherein the gas barrier layer comprises an aluminum alloy thin film, wherein the sealant layer has a thickness of 70 μm to 100 μm, and wherein a thickness ratio of the drawing assistance layer to the gas barrier layer is in a range of 1:1.5 to 1:2.5.
  17. 17 . A pouch type secondary battery comprising an electrode assembly which is formed by stacking a positive electrode, a separator, and a negative electrode; and a pouch type battery case accommodating the electrode assembly, wherein the battery case is prepared by forming a pouch film laminate, wherein the pouch film laminate comprises: a sealant layer formed of a first polymer as an innermost layer; a surface protection layer formed of a second polymer as an outermost layer; a gas barrier layer laminated between the surface protection layer and the sealant layer; and a drawing assistance layer formed of a third polymer and laminated between the surface protection layer and the gas barrier layer, wherein the gas barrier layer has a thickness of 50 μm to 70 μm, wherein the gas barrier layer comprises an aluminum alloy thin film, wherein the sealant layer has a thickness of 70 μm to 100 μm, and wherein a thickness ratio of the drawing assistance layer to the gas barrier layer is in a range of 1:1.5 to 1:2.5.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/007175 filed on Jun. 8, 2021, which claims priority from Korean Patent Application No. 10-2020-0069917, filed on Jun. 9, 2020, the disclosures of which are incorporated by reference herein. TECHNICAL FIELD The present invention relates to a pouch film laminate, a pouch type battery case, and a pouch type secondary battery, and more particularly, to a pouch film laminate in which formability is improved by improving tensile strength and elongation, a pouch type battery case, and a pouch type secondary battery. BACKGROUND ART In general, types of secondary batteries include a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, and a lithium ion polymer battery. These secondary batteries are not only applied and used in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but are also applied and used in large products requiring high output, such as electric vehicles and hybrid vehicles, and a power storage device and a power storage device for backup which store surplus generated power or renewable energy. In order to prepare such a secondary battery, first, a positive electrode collector and a negative electrode collector are respectively coated with electrode active material slurries to prepare a positive electrode and a negative electrode, and the positive electrode and the negative electrode are then stacked on both sides of a separator to form an electrode assembly having a predetermined shape. Then, after the electrode assembly is accommodated in a battery case and an electrolyte solution is injected, the battery case is sealed. The secondary battery is classified into a pouch type, a can type, and the like, according to a material of a case for accommodating the electrode assembly. The pouch type accommodates the electrode assembly in a pouch formed of a flexible polymer material. In addition, the can type accommodates the electrode assembly in a case formed of a material such as metal or plastic. The pouch, which is a case of the pouch type secondary battery, is prepared by press working of a flexible pouch film laminate to form a cup portion. Then, when the cup portion is formed, the electrode assembly is accommodated in an accommodating space of the cup portion and a sealing portion is sealed to prepare a secondary battery. Drawing in the press working is performed by inserting the pouch film laminate into press equipment and applying a pressure to the pouch film laminate with a punch to stretch the pouch film laminate. The pouch film laminate is generally composed of a plurality of layers in which a polymer film, such as polyethylene terephthalate, is laminated on one surface of a metal gas barrier layer and a sealant layer is laminated on the other surface thereof, and an about 40 μm thick aluminum alloy thin film is mainly used as the gas barrier layer. However, such a conventional pouch film laminate had a limitation in forming a deeper cup portion due to low formability, and also had a limitation in reducing a radius of filleting when edges of a bottom portion and edges of an open portion of the cup portion are filleted. Furthermore, the conventional pouch film laminate had a limitation in forming an outer wall of the cup portion close to vertical. Accordingly, there was a problem in that a dead space of the secondary battery was increased and a size of the electrode assembly was decreased to reduce energy efficiency to volume. DISCLOSURE OF THE INVENTION Technical Problem An aspect of the present invention provides a pouch film laminate, in which formability is excellent by improving tensile strength and elongation, a pouch type battery case, and a pouch type secondary battery. The object of the present invention is not limited to the aforesaid, but other objects not described herein will be clearly understood by those skilled in the art from descriptions below. Technical Solution According to an aspect of the present invention, there is provided a pouch film laminate including: a sealant layer formed of a first polymer as an innermost layer; a surface protection layer formed of a second polymer as an outermost layer; an aluminum alloy thin film having a grain size of 10 μm to 13 μm, and a gas barrier layer laminated between the surface protection layer and the sealant layer, wherein the gas barrier layer has a thickness of 50 μm to 70 μm, and the sealant layer has a thickness of 70 μm to 100 μm. Also, the aluminum alloy thin film may be an aluminum alloy thin film with alloy number AA8021. Furthermore, the aluminum alloy thin film may include iron in an amount of 1.3 wt % to 1.7 wt %. Also, the aluminum alloy thin film may include silicon in an amount of 0.2 wt % or less. Furthermore, the gas barrier layer may have a thickness of 55 μm to 65 μm. Also, the