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EP-4401188-B1 - JELLY ROLL-TYPE ELECTRODE ASSEMBLY AND SECONDARY BATTERY COMPRISING SAME

EP4401188B1EP 4401188 B1EP4401188 B1EP 4401188B1EP-4401188-B1

Inventors

  • KOO, SEONGMO
  • KIM, YOUNG SOO
  • PARK, EUN JI
  • LEE, KWAN SOO
  • LEE, Byeongjoon

Dates

Publication Date
20260506
Application Date
20230818

Claims (12)

  1. A jelly-roll type electrode assembly in which a first separator (200), a negative electrode (100), a second separator (400), and a positive electrode (300) are sequentially stacked and wound, wherein the positive electrode (300) has a first surface in a direction of a winding axis of the jelly-roll type electrode assembly, and a second surface opposite to the first surface, wherein a core part of the electrode assembly comprises a separator overlapping portion (S) between the positive electrode (300) and the negative electrode (100) facing the first surface of the positive electrode (300), and wherein the separator overlapping portion (S) comprises separators that are overlapped and arranged and are in three or more folds, wherein the separator overlapping portion (S) comprises a first interface (S1) at which the second separator (400) and the second separator (400') are in direct contact with each other, and a second interface (S2) at which the second separator (400') and the first separator (200') are in direct contact with each other, and wherein a friction coefficient of the first interface (S1) is 0.6 or greater, and wherein a friction coefficient of the second interface (S2) is 0.4 or greater, as measured in accordance with the ASTM D 1894 standard, and wherein the first separator (200, 200') and the second separator (400, 400') each comprise a coating layer (202, 202', 402, 402') provided on at least one surface thereof, and wherein the surface of each of the first separator (200, 200') and the second separator (400, 400'), on which the coating layer (202, 202', 402, 402') is provided, has a greater friction coefficient than that of a surface of each of the first separator (200, 200') and the second separator (400, 400'), on which the coating layer (202, 202', 402, 402') is not provided.
  2. The jelly-roll type electrode assembly of claim 1, wherein at the core part of the electrode assembly, the first separator (200), the negative electrode (100), and the second separator (400) extend longer than a longitudinal end portion of the positive electrode (310) and are additionally wound.
  3. The jelly-roll type electrode assembly of claim 1, wherein in the separator overlapping portion (S), the first separator (200') and the second separator (400') extending from a longitudinal end portion of the negative electrode (110) at the core part of the electrode assembly are overlapped and arranged.
  4. The jelly-roll type electrode assembly of claim 1, wherein the first separator (200') and the second separator (400'), extend from a longitudinal end portion of the negative electrode (110) at the core part of the electrode assembly, are bent together in an opposite direction to a direction facing a winding axis of the negative electrode (100), and are overlapped and arranged between the positive electrode (300) and the second separator (400) facing the first surface of the positive electrode (300).
  5. The jelly-roll type electrode assembly of claim 1, wherein the first separator (200, 200') and the second separator (400, 400') each comprise a coating layer (202, 202', 402, 402') provided on at least one surface thereof, and wherein the coating layer (202, 202', 402, 402') comprises an inorganic component, a binder component and a lithium salt.
  6. The jelly-roll type electrode assembly of claim 1, wherein the first separator (200, 200') and the second separator (400, 400') each comprise a coating layer (202, 202', 402, 402') provided on one surface thereof, and wherein the first interface (S1) is an interface at which the coating layer (402) of the second separator (400) and the coating layer (402') of the second separator (400') are in direct contact with each other.
  7. The jelly-roll type electrode assembly of claim 1, wherein the first separator (200, 200') and the second separator (400, 400') each comprise a coating layer (202, 202', 402, 402') provided on one surface thereof, and wherein the second interface (S2) is an interface at which a surface of the second separator (400, 400') on which a coating layer (402, 402') is not provided and a surface of the first separator (200, 200') on which a coating layer (202, 202') is not provided are in direct contact with each other.
  8. The jelly-roll type electrode assembly of claim 1, wherein the first interface (S1) is an interface at which the second separator (400) facing the first surface of the positive electrode (300) and the second separator (400') extending from a longitudinal end portion of the negative electrode (110) at the core part of the electrode assembly are in direct contact with each other.
  9. The jelly-roll type electrode assembly of claim 1, wherein the second interface (S2) is an interface at which the first separator (200') extending from a longitudinal end portion of the negative electrode (110) at the core part of the electrode assembly and the second separator (400') extending from the longitudinal end portion of the negative electrode (110) at the core part of the electrode assembly are in direct contact with each other.
  10. The jelly-roll type electrode assembly of claim 1, wherein a length, in a longitudinal direction, of the separator overlapping portion (S) is 30% or more based on 100% of a circumference of the electrode assembly.
  11. The jelly-roll type electrode assembly of claim 1, wherein a spacing distance (L) between a longitudinal end portion of the separator overlapping portion and a longitudinal end portion of the positive electrode is 3 mm or longer.
  12. A secondary battery comprising: the jelly-roll type electrode assembly according to any one of Claims 1 to 11; and a battery case for accommodating the electrode assembly.

Description

[Technical Field] The present invention relates to a jelly-roll type electrode assembly and a secondary battery including the same, and more particularly, to a jelly-roll type electrode assembly including a separator overlapping portion and a cylindrical secondary battery including the same. [Background Art] For a cylindrical battery, a jelly-roll type electrode assembly is manufactured by rolling a long electrode having a prescribed width into a roll form. In a cylindrical battery manufactured by inserting such a jelly-roll type electrode assembly into a battery case, contraction/expansion of the electrode repeatedly occurs during charging and discharging. In particular, when a degree of contraction/expansion of the electrode assembly increases due to a tab (in tab) located in a core of the jelly-roll type electrode assembly or a silicon-based active material added in a negative electrode, a pressure acting on a core part of the electrode assembly greatly increases. As low-resistance/high-capacity designs increase recently, a jelly-roll type electrode assembly includes a plurality of tabs or a silicon-based active material is added, in many cases. Accordingly, the possibility of deformation of the electrode assembly located in the core part according to contraction/expansion of the electrode assembly increases. In particular, when a separator located between the negative electrode and the positive electrode is damaged, the negative electrode and the positive electrode come into direct contact with each other, causing heat generation and ignition due to an internal short. In order to solve the problems of the separator damage and internal short caused by the deformation of the electrode assembly, it is necessary to develop a technology capable of protecting the negative electrode and separator in the corresponding region and suppressing the occurrence of the internal short. WO 2023/106 733 A1 relates to a jelly-roll type electrode assembly including an overlapping portion of a separator and a cylindrical secondary battery including the same, and more specifically to a first separator. It also relates to a jelly-roll type electrode assembly including an adhesive and a second separator overlapping portion, and a cylindrical secondary battery including the same. US 2022/352 601 A1 discloses a secondary battery including a battery device, a positive electrode terminal, a negative electrode terminal, and a porous member. The battery device includes a positive electrode and a negative electrode that are opposed to each other with a separator interposed therebetween. The positive electrode terminal is coupled to the positive electrode on a side of the positive electrode opposed to the negative electrode. The negative electrode terminal is coupled to the negative electrode on a side of the negative electrode opposed to the positive electrode. The negative electrode terminal is positioned not to be opposed to the positive electrode terminal. The porous member is disposed in a region sandwiched by the positive electrode terminal and the negative electrode terminal. US 2004/180 259 A1 describes an electrode unit and a secondary battery having the electrode unit including a first electrode plate having a first electrode uncoated portion on at least one side of a first electrode collector coated with at least a first electrode active material, a second electrode plate having a second electrode uncoated portion on at least one side of a second electrode collector coated with at least a second electrode active material, and a separator interposed between the first electrode plate and the second electrode plate, wherein an insulating separator having at least two folds is located between the first electrode uncoated portion and the second electrode uncoated portion. KR 2015 0 015 253 A provides a secondary battery that can prevent the damage of a separator caused by burr formed on the thickness of a coating part and the end part of a current collector in a process of cutting electrodes in which a current collector is coated with active materials. A secondary battery includes an electrode assembly formed by stacking a first electrode, a first separator, a second electrode and a second separator from the center in a sequence and by winding the same; a case having the electrode assembly; and a cap assembly connected to an opening part of the case wherein the first and the second separator surround the end parts of the first electrode and the second electrode in the center and are allowed to form a re-winding part installed between the first electrode and the second electrode in a diameter direction. JP 2003 303 624 A describes a non-aqueous electrolyte secondary battery that comprises a wound electrode body that is wound in spiral form by interposing a separator, 18 between a positive electrode and a negative electrode of belt-shape formed with a mixture layer on the belt-shape current collector and a battery case in which th