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EP-4738549-A1 - SECONDARY BATTERY AND CASE FOR SECONDARY BATTERY

EP4738549A1EP 4738549 A1EP4738549 A1EP 4738549A1EP-4738549-A1

Abstract

A secondary battery includes: an electrode assembly (110); a lower case (120) including a receiving part (127) having a receiving space for accommodating the electrode assembly (110), and a flange part (128) surrounding around an open side surface of the receiving part (127); and an upper cover (130) coupled to the flange part (128) of the lower case (120), and sealing the open side surface of the receiving part (127). The receiving part (127) of the lower case (120) includes a bottom surface (140) spaced from the flange part (128), and a sidewall part (150) connecting the flange part (128) and the bottom surface (140) to each other. At least one edge of the sidewall part (150) has a rounded shape including a curved surface having a first radius (R1) of curvature, and a curved surface having a second radius (R2) of curvature coupled to the curved surface having the first radius (R1) of curvature. The first radius (R1) of curvature is larger than the second radius (R2) of curvature.

Inventors

  • LEE, JEAWOAN

Assignees

  • SAMSUNG SDI CO., LTD.

Dates

Publication Date
20260506
Application Date
20251105

Claims (15)

  1. A secondary battery (100) comprising: an electrode assembly (110) comprising a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a lower case (120) comprising a receiving part (127) having a receiving space for accommodating the electrode assembly (110), and a flange part (128) surrounding around an open side surface of the receiving part (127); and an upper cover (130) coupled to the flange part (128) of the lower case (120), and sealing the open side surface of the receiving part (127), wherein the receiving part (127) of the lower case (120) comprises a bottom surface (140) spaced from the flange part (128), and a sidewall part (150) connecting the flange part (128) and the bottom surface (140) to each other, wherein at least one edge of the sidewall part (150) has a rounded shape comprising a curved surface having a first radius (R1) of curvature, and a curved surface having a second radius (R2) of curvature coupled to the curved surface having the first radius (R1) of curvature, and wherein the first radius (R1) of curvature is larger than the second radius (R2) of curvature.
  2. The secondary battery (100) as claimed in claim 1, wherein at least one of the upper cover (130) or the lower case (120) comprises stainless use steel (SUS).
  3. The secondary battery (100) as claimed in claim 1 or 2, wherein a size of the first radius (R1) of curvature is increased as a thickness of the lower case (120) is reduced.
  4. The secondary battery (100) as claimed in any of the preceding claims, wherein a thickness of the lower case (120) is in a range of 0.02 mm to 0.1 mm.
  5. The secondary battery (100) as claimed in any of the preceding claims, wherein a thickness of the lower case (120) is in a range of 0.02 mm to 0.04 mm, and a size of the first radius (R1) of curvature is in a range of 3.0 mm to 6.0 mm.
  6. The secondary battery (100) as claimed in any of the preceding claims, wherein a size of the first radius (R1) of curvature is in a range of 2.0 mm to 6.0 mm.
  7. The secondary battery (100) as claimed in any of the preceding claims, wherein a depth of the receiving part (127) is larger than 0 mm and equal to or less than 5.0 mm.
  8. The secondary battery (100) as claimed in any of the preceding claims, wherein the sidewall part (150) comprises: a first side surface (152) connected to one short side of the bottom surface (140); a second side surface (154) facing the first side surface (152); a third side surface (156) connected to one long side of the bottom surface (140); and a fourth side surface (158) facing the thrid side surface (156).
  9. The secondary battery (100) as claimed in claim 8, wherein a first electrode terminal (122) electrically connected to the first electrode and a second electrode terminal (124) electrically connected to the second electrode are located on at least a portion of the first side surface (152).
  10. The secondary battery (100) as claimed in claim 8 or 9, wherein each of an edge in which the first side surface (152) and the third side surface (156) are coupled to each other, an edge in which the first side surface (152) and the fourth side surface (158) are coupled to each other, an edge in which the second side surface (154) and the third side surface (156) are coupled to each other, and an edge in which the second side surface (154) and the fourth side surface (158) are coupled to each other has a rounded shape in which the curved surface having the first radius (R1) of curvature and the curved surface having the second radius (R2) of curvature are coupled to each other.
  11. The secondary battery (100) as claimed in claim 10, wherein the curved surface having the first radius (R1) of curvature is connected to at least one of the first side surface (152) or the second side surface (154), and wherein the curved surface having the second radius (R2) of curvature is connected to at least one of the third side surface (156) or the fourth side surface (158).
  12. The secondary battery (100) as claimed in claim 10 or 11, wherein each of an edge in which the bottom surface (140) and the first side surface (152) are coupled to each other and an edge in which the bottom surface (140) and the second side surface (154) are coupled to each other has a curved surface having a third radius (R3) of curvature, and wherein each of an edge in which the bottom surface (140) and the third side surface (156) are coupled to each other and an edge in which the bottom surface (140) and the fourth side surface (158) are coupled to each other has a curved surface having a fourth radius (R4) of curvature.
  13. The secondary battery (100) as claimed in claim 12, wherein the third radius (R3) of curvature is same as the fourth radius (R4) of curvature.
  14. The secondary battery (100) as claimed in claim 12 or 13, wherein a size of the third radius (R3) of curvature and a size of the fourth radius (R4) of curvature are increased as a thickness of the lower case (120) is reduced.
  15. The secondary battery (100) as claimed in any of the preceding claims, wherein at least a portion of the upper cover (130) is joined to the flange part (128) of the lower case (120) by laser welding.

Description

BACKGROUND 1. Field The present invention relates to a secondary battery. 2. Description of the Related Art Unlike primary batteries that are not designed to be (re)charged, secondary (or rechargeable) batteries are batteries that are designed to be discharged and recharged. Low-capacity secondary batteries are used in portable, small electronic devices, such as smart phones, feature phones, notebook computers, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for driving motors in hybrid vehicles and electric vehicles and for storing power (e.g., home and/or utility scale power storage). A secondary battery generally includes an electrode assembly composed of a positive electrode and a negative electrode, a case accommodating the same, and electrode terminals connected to the electrode assembly. A secondary battery having high energy density (e.g., an amount of energy to be storable per unit volume) may provide a longer runtime or longer mileage in portable devices or electric vehicles, and the energy density of the secondary battery may be one of key factors that determine a performance of the secondary battery. Accordingly, various technologies for increasing the energy density, for example, such as by improving a structure of a case in the secondary battery, may be desired. The above information disclosed in this background section is for enhancement of understanding of the background of the present invention, and therefore, it may contain information that does not constitute related (or prior) art. SUMMARY The present invention is directed to a secondary battery. These and other aspects and features of the present invention will be described in or will be apparent from the following description of embodiments of the present invention. According to the present invention, a secondary battery includes: an electrode assembly including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a lower case including a receiving part having a receiving space for accommodating the electrode assembly, and a flange part surrounding around an open side surface of the receiving part; and an upper cover coupled to the flange part of the lower case, and sealing the open side surface of the receiving part. The receiving part of the lower case includes a bottom surface spaced from the flange part, and a sidewall part connecting the flange part and the bottom surface to each other. At least one edge of the sidewall part has a rounded shape including a curved surface having a first radius of curvature, and a curved surface having a second radius of curvature coupled to the curved surface having the first radius of curvature. The first radius of curvature is larger than the second radius of curvature. In an embodiment, at least one of the upper cover or the lower case includes stainless use steel (SUS). In an embodiment, a size of the first radius of curvature may be increased as a thickness of the lower case is reduced. In an embodiment, a thickness of the lower case may be in a range of 0.02 mm to 0.1 mm. In an embodiment, a thickness of the lower case may be in a range of 0.02 mm to 0.04 mm, and a size of the first radius of curvature may be in a range of 3.0 mm to 6.0 mm. In an embodiment, a size of the first radius of curvature may be in a range of 2.0 mm to 6.0 mm. In an embodiment, a depth of the receiving part may be larger than 0 mm and equal to or less than 5.0 mm. In an embodiment, the sidewall part may include: a first side surface connected to one short side of the bottom surface; a second side surface facing the first side surface; a third side surface connected to one long side of the bottom surface; and a fourth side surface facing the third side surface. In an embodiment, a first electrode terminal electrically connected to the first electrode and a second electrode terminal electrically connected to the second electrode may be located on at least a portion of the first side surface. In an embodiment, each of an edge in which the first side surface and the third side surface are coupled to each other, an edge in which the first side surface and the fourth side surface are coupled to each other, an edge in which the second side surface and the third side surface are coupled to each other, and an edge in which the second side surface and the fourth side surface are coupled to each other may have a rounded shape in which the curved surface having the first radius of curvature and the curved surface having the second radius of curvature are coupled to each other. In an embodiment, the curved surface having the first radius of curvature may be connected to at least one of the first side surface or the second side surface, and the curved surface having the second radius of curvature may be connected to at least one of the third side surface or the fourth side surface. In an embodiment, each of