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EP-4238163-B1 - ELECTRODE ASSEMBLY

EP4238163B1EP 4238163 B1EP4238163 B1EP 4238163B1EP-4238163-B1

Inventors

  • KIM, Beomsu
  • KWON, CHUN HO
  • YOON, SE HYUN
  • LEE, HAKSOO
  • JANG, HYEON WOO
  • KIM, YONG NAM
  • PARK, DONG HYEUK

Dates

Publication Date
20260506
Application Date
20220708

Claims (10)

  1. An electrode assembly, comprising: a stack (S) including first electrodes (1), a first separator (4) folded in a zigzag configuration and including spacer sections (4a) and respective side sections (4b) between the spacer sections (4a), and second electrodes (2), the first (1) and the second (2) electrodes being alternately disposed between the spacer sections (4a) of the first separator (4); and a second separator (5) extending along an upper surface, a lower surface, and at least one pair of opposing side surfaces of the stack (S), wherein the side sections (4b) of the first separator (4) define portions of the side surface of the stack (S) on which the first electrodes (1) and the second electrodes (2) are not disposed, and wherein the second separator (5) is bonded to at least one of the side sections (4b); wherein two or more of the side sections (4b) are bonded to each other, and the second separator (5) is bonded to at least a portion of the side sections (4b) that are bonded to each other; characterized in that an area of the second separator (5) that is bonded to the side sections (4b) of the first separator (4) in which two or more side sections (4b) are bonded to each other is 30% or more of the total area of an inner separator surface of the second separator (5) positioned facing the opposing side surfaces of the stack (S).
  2. The electrode assembly of claim 1, wherein the side sections (4b) are positioned on alternating sides of the first (1) and the second (2) electrodes of the stack (S).
  3. The electrode assembly of claim 1, wherein the number of the side sections (4b) of the first separator (4) bonded to the second separator (5) is 30% or more of the total number of the side sections (4b).
  4. The electrode assembly of claim 3, wherein each of the spacer sections (4a) of the first separator (4) has the same length as a length of the first (1) and the second (2) electrodes of the stack (S), and wherein each of the side sections (4b) extends between respective adjacent pairs of the spacer sections (4a).
  5. The electrode assembly of claim 1, wherein the side sections (4b) are bent one or more times in directions parallel to a stacking direction of the stack (S).
  6. The electrode assembly of claim 1, wherein a length of one of the side sections (4b) is 0.1% to 1% of the total length of the spacer section (4a) to which the one of the side sections (4b) is attached.
  7. The electrode assembly of claim 1, wherein the first separator (4) is bonded to at least one of the first electrodes (1) and to at least one of the second electrodes (2).
  8. The electrode assembly of claim 1, wherein the second separator (5) is bonded to at least one of the first electrodes (1) and to at least one of the second electrodes (2).
  9. The electrode assembly of claim 1, wherein an end of the first separator (4) is shared with an end of the second separator (5) such that the second separator (5) is a continuation of the first separator (4).
  10. The electrode assembly of claim 1, wherein the first separator (4) and the second separator (5) lack common ends.

Description

[Technical Field] This application claims priority from Korean Patent Application No. 10-2021-0090590 filed on July 9, 2021, Korean Patent Application No. 10-2021-0090591 filed on July 09, 2021. The present disclosure relates to an electrode assembly. More particularly, the present disclosure relates to an electrode assembly with a separator of reduced dimensions for increasing an electrode density of the electrode assembly. [Background Art] Secondary batteries, unlike primary batteries, are rechargeable and have been widely researched and developed in recent years due to their small size and large capacity. As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. The secondary battery is classified into a coin-type battery, a cylindrical battery, a prismatic battery, and a pouch-type battery according to a shape of a battery case. In a secondary battery, an electrode assembly mounted inside a battery case is a chargeable/dischargeable power generating element having a stacked structure of an electrode and a separator. The electrode assembly may be generally classified into a jelly-roll type in which a separator is interposed between a positive electrode and a negative electrode of a sheet type coated with an active material and wound, a stack type in which pluralities of positive and negative electrodes are sequentially stacked with a separator interposed therebetween, and a stack-and-folding type in which stacked unit cells are wound with a long-length separation film. In a process of manufacturing a stack-and-folding type electrode assembly in the related art, an electrode assembly was manufactured by heating and compressing a stack in which an electrode and a separator are stacked to bond the electrode and the separator. At this stage in the electrode assembly process, the separator is folded but the electrode is externally exposed. By heating and stacking the electrode and the separator in order to overcome certain deficiencies of conventional electrode assemblies, each layer is stacked and compressed so that the layers are bonded simultaneously with their stacking, and an outer portion of the separator is wrapped around the outermost portion of the stack of the electrode and the separator such that the stack is surrounded by the outer portion of the separator to thereby form an electrode assembly. JP2016103425A relates to a zigzag structure in a stack structure of a secondary battery. However, in this electrode assembly, a space is formed between the side portion of the separator positioned on a side of the electrode assembly and a portion of the electrode on the side of the electrode assembly due to the separator surrounding the outermost portion of the stack, so that the side separator portion of the electrode assembly includes wrinkles. This configuration leads to an undesirable reduction in the energy density of the electrode assembly. Therefore, there is a need to address the space formed between the side portion of the separator and the portion of the electrode on the side of the electrode assembly. [Disclosure] [Technical Problem] The present disclosure provides for an electrode assembly in which a width of the electrode assembly may be reduced by surrounding the outermost portion of a stack with an outermost separator in which electrodes and sections of the separator or of another separator are stacked with the separator to form the stack. A portion of the outermost separator positioned along a side of the stack may be condensed, and thereby condense the stack, by heating and compressing the side of the stack. [Technical Solution] The invention relates to an electrode assembly as recited in claim 1. In some arrangements, each of the side sections may include folded parts of the first separator. In some arrangements, the side sections may be positioned on alternating sides of the first and the second electrodes of the stack. In some arrangements, the number of the side sections of the first separator bonded to the second separator may be 30% or more of the total number of the side sections. In some arrangements, each of the spacer sections of the first separator may have the same length as a length of the first and the second electrodes of the stack. In some such arrangements, each of the side sections may extend between respective adjacent pairs of the spacer sections. As recited in claim 1, two or more of the side sections are bonded to each other and the second separat is bonded to at least a portion of the side sections that are bonded to each other. As recited in claim 1, an area of the second separator that is bonded to the side sections of the first separator in which two or more folded parts are bonded to each is 30% or more of the total area of an inner separator surface of the second separator positioned facing the side surfaces of the stack. In some arrangements, the side sections may be bent one o