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EP-4418414-B1 - POUCH-TYPE SECONDARY BATTERY, SECONDARY BATTERY MODULE INCLUDING SAME, AND POUCH USED THEREFOR

EP4418414B1EP 4418414 B1EP4418414 B1EP 4418414B1EP-4418414-B1

Inventors

  • CHOI, YONG JOON
  • KIM, SOO YOUL
  • LEE, DONG SU

Dates

Publication Date
20260506
Application Date
20221014

Claims (7)

  1. A pouch type secondary battery (10) comprising: an electrode assembly (100), having an electrode and a separator; a pouch (200) in which the electrode assembly (100) is embedded; an electrode lead (300) connected to the electrode and protruding from the pouch (200) toward the outside; and a lead film (300') made of an electrically insulating material attached to each of both surfaces of the electrode lead (300); wherein the pouch (200) comprises an upper pouch portion and a lower pouch portion; an accommodation part (210) between the upper pouch portion and the lower pouch portion in which the electrode assembly (100) is accommodated; and an edge part (220) obtained by sealing the upper pouch portion and the lower pouch portion along an outer circumference of the accommodation part (210) to define an edge, wherein, at the edge part (220), the upper pouch portion and the lower pouch portion are each made of a first insulating layer (222a), a metal layer (222c), and a second insulating layer (222b) stacked in sequence from the inside toward the outside of the pouch (200), thereby defining a coating edge part (222) except at a position corresponding to the electrode lead (300), where the upper pouch portion and the lower pouch portion are each made of a first electrically insulating layer (221a) and a second electrically insulating layer (221b) stacked in sequence from the inside toward the outside of the pouch (200), and disposed so as to surround the lead film (300'), thereby defining an insulating edge part (221), characterized in that the width of the lead film (300'), measured in a direction where the electrically insulating edge part (221) and the coating edge part (222) are adjacent, is larger than the width of the electrode lead (300) and wherein a difference between a width of the electrically insulating edge part (221) disposed so as to surround the lead film (300') and a width of the lead film (300') is equal to or greater than a difference between the width of the lead film (300') and a width of the electrode lead (300).
  2. The pouch (200) type secondary battery (10) of claim 1, wherein the electrode lead (300) protrudes from at least one end of the pouch (200) toward the outside.
  3. The pouch (200) type secondary battery (10) of claim 1, wherein at least one of the first electrically insulating layer (210a, 221a) or the second electrically insulating layer (210b, 221b) has a synthetic resin material.
  4. The pouch (200) type secondary battery (10) of claim 3, wherein the first electrically insulating layer (210a, 221a) comprises polypropylene (PP).
  5. The pouch (200) type secondary battery (10) of claim 3, wherein the second insulating layer (210b, 221b) comprises polyethylene terephthalate (PET).
  6. A secondary battery module comprising a plurality of pouch type secondary batteries (100) according to claim 1.
  7. A pouch sealing method for sealing a pouch type secondary battery (10) according to one of the preceding claims at an edge of a pouch (200) in which an electrode assembly (100) comprising an electrode and a separator is embedded, the pouch sealing method comprising: providing a pouch (200) comprising an accommodation part (210) in which the electrode assembly (100) is accommodated; and an edge part (220) disposed along an outer circumference of the accommodation part (210) to define an edge, the edge part (220) comprising an electrically insulating edge part (221) having an electrically insulating material, the edge part (220) further comprising a coating edge part (222) which includes, in addition to the first insulating layer and the second insulating layer, a metal layer (222c) disposed therebetween, a first sealing step of sealing an electrically insulating edge part (221); and a second sealing step of sealing the coating edge part (222) at a portion of the edge excluding the electrically insulating edge part (221), wherein a sealing temperature in the second sealing step is higher than a sealing temperature in the first sealing step.

Description

TECHNICAL FIELD CROSS-REFERENCE TO RELATED APPLICATION The present application claims the benefit of the priority of Korean Patent Application Nos. 10-2021-0136975, filed on October 14, 2021, and 10-2022-0130928, filed on October 12, 2022. TECHNICAL FIELD The present disclosure relates to a pouch type secondary battery, a secondary battery module including the same, and a pouch sealing method for sealing such a pouch type secondary battery, with the aim to provide a pouch type secondary battery with improved electrically insulation performance, and a secondary battery module including the same. BACKGROUND ART JP 2006 339042 A relates to a battery, and more particularly to a battery having a battery case made of a laminate film formed by laminating a metal film and a resin film. Batteries (cells) that generate electrical energy through a physical reaction or a chemical reaction of a substance to supply power to the outside are used when AC power to be supplied to a building is not obtained or DC power is required, according to living environments surrounded by various electronic devices. Among such batteries, primary batteries and secondary batteries that are chemical batteries using the chemical reaction are generally used a lot. The primary batteries are consumable batteries that are collectively referred to as dry batteries. The secondary batteries are rechargeable batteries that are manufactured using a material in which a redox process between a current and a material is repeatable several times. When a reduction reaction is performed on the material by the current, power is charged, and when an oxidation reaction is performed on the material, power is discharged. Such a charging-discharging is repeatedly performed to generate electricity. In recent market, attention has been paid to a pouch type secondary battery 1 having a small volume and a high degree of freedom in design. In more detail, as illustrated in FIG. 1a, the pouch type secondary battery 1 may include an electrode assembly 1a including a positive electrode/separator/negative electrode, a pouch 1b in which the electrode assembly 1a is accommodated, and an electrode lead 1c electrically connected to the positive electrode/negative electrode of the outside of the electrode assembly 1a and protruding from the outside of the pouch 1b. Here, a lead film 1c' made of an electrically insulating material may be attached to each of both surfaces of the electrode lead 1c. Here, the pouch 1b is constituted generally by a stack of various thin functional films. As a representative example, the pouch 1b may have a structure in which an inner electrically insulating layer 1ba for isolation of internal components of the pouch 1b, a metal layer 1bc that maintains mechanical strength of the pouch 1b, and an outer electrically insulating layer 1bb that electrically insulates the metal layer 1bc from an external component, are stacked in sequence from the inside toward the outside, as illustrated in FIG. 1b. However, the pouch type secondary battery 1 having such a structure has problems that as the metal layer 1bc is exposed to the outside at a side surface of an edge of the pouch 1b, a leakage current occurs to degrade performance of the secondary battery. In particular, there is a problem that due to failure to secure a sufficient separation distance for electrical insulation between the metal layer 1bc exposed to the outside and the electrode lead 1c, an arc occurs during applying an external voltage to cause damage (e.g., burn mark) to the secondary battery 10 (1) (see FIG. 1c). When the pouch type secondary battery 1 having the structure as described above is used to provide one secondary battery module, electrical insulation between the metal layer 1bc of the pouch type secondary battery 1 and a module housing (not shown) made of a metal material is required. Thus, there is a problem of requiring an additional electrical insulation design, for example, the pouch type secondary battery 1 is disposed apart from the module housing or a structure made of an electrically insulating material is inserted between the pouch type secondary battery 1 and the module housing. DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM The present invention has been devised to solve the problems as above and an object of the present invention is to provide a pouch type secondary battery with improved electrical insulation performance, a secondary battery module comprising a plurality of such pouch type secondary batteries, and a pouch sealing method for sealing such a pouch type secondary battery. TECHNICAL SOLUTION The present invention provides a pouch type secondary battery as defined in claim 1; a secondary battery module comprising a plurality of such pouch type secondary batteries, as defined in claim 6; and a pouch sealing method for sealing such a pouch type secondary battery, as defined in claim 7. Accordingly, the pouch type secondary battery includes an electrode lead c