US-20260128424-A1 - SECONDARY BATTERY AND CASE FOR SECONDARY BATTERY

US20260128424A1US 20260128424 A1US20260128424 A1US 20260128424A1US-20260128424-A1

Abstract

A secondary battery includes: an electrode assembly; 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.

Inventors

Jeawoan Lee

Assignees

SAMSUNG SDI CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20250818
Priority Date: 20241105

Claims (20)

1 . A secondary battery comprising: an electrode assembly comprising a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a lower case comprising 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, wherein the receiving part of the lower case comprises a bottom surface spaced from the flange part, and a sidewall part connecting the flange part and the bottom surface to each other, wherein at least one edge of the sidewall part has a rounded shape comprising 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, and wherein the first radius of curvature is larger than the second radius of curvature.
2 . The secondary battery as claimed in claim 1 , wherein at least one of the upper cover or the lower case comprises stainless use steel (SUS).
3 . The secondary battery as claimed in claim 1 , wherein a size of the first radius of curvature is increased as a thickness of the lower case is reduced.
4 . The secondary battery as claimed in claim 1 , wherein a thickness of the lower case is in a range of 0.02 mm to 0.1 mm.
5 . The secondary battery as claimed in claim 1 , wherein a thickness of the lower case is in a range of 0.02 mm to 0.04 mm, and a size of the first radius of curvature is in a range of 3.0 mm to 6.0 mm.
6 . The secondary battery as claimed in claim 1 , wherein a size of the first radius of curvature is in a range of 2.0 mm to 6.0 mm.
7 . The secondary battery as claimed in claim 1 , wherein a depth of the receiving part is larger than 0 mm and equal to or less than 5.0 mm.
8 . The secondary battery as claimed in claim 1 , wherein the sidewall part comprises: 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.
9 . The secondary battery as claimed in claim 8 , wherein a first electrode terminal electrically connected to the first electrode and a second electrode terminal electrically connected to the second electrode are located on at least a portion of the first side surface.
10 . The secondary battery as claimed in claim 8 , wherein 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 has 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.
11 . The secondary battery as claimed in claim 10 , wherein the curved surface having the first radius of curvature is connected to at least one of the first side surface or the second side surface, and wherein the curved surface having the second radius of curvature is connected to at least one of the third side surface or the fourth side surface.
12 . The secondary battery as claimed in claim 10 , wherein each of an edge in which the bottom surface and the first side surface are coupled to each other and an edge in which the bottom surface and the second side surface are coupled to each other has a curved surface having a third radius of curvature, and wherein each of an edge in which the bottom surface and the third side surface are coupled to each other and an edge in which the bottom surface and the fourth side surface are coupled to each other has a curved surface having a fourth radius of curvature.
13 . The secondary battery as claimed in claim 12 , wherein the third radius of curvature is same as the fourth radius of curvature.
14 . The secondary battery as claimed in claim 12 , wherein a size of the third radius of curvature and a size of the fourth radius of curvature are increased as a thickness of the lower case is reduced.
15 . The secondary battery as claimed in claim 1 , wherein at least a portion of the upper cover is joined to the flange part of the lower case by laser welding.
16 . The secondary battery as claimed in claim 1 , wherein each of at least a portion of the upper cover and at least a portion of the lower case has a stack structure comprising: a metal layer; an adhesive layer in contact with the metal layer; and a polymer layer in contact with the adhesive layer, and wherein the at least a portion of the upper cover is joined to the flange part of the lower case by heat staking of the polymer layer of the at least a portion of the upper cover and the polymer layer of the at least a portion of the lower case to each other.
17 . A case for a secondary battery, comprising: a lower case comprising a receiving part having a receiving space for accommodating an 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, wherein the receiving part of the lower case comprises a bottom surface spaced from the flange part, and a sidewall part connecting the flange part and the bottom surface to each other, wherein at least one edge of the sidewall part has a rounded shape comprising 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, and wherein the first radius of curvature is larger than the second radius of curvature.
18 . The case for the secondary battery as claimed in claim 17 , wherein the sidewall part comprises: 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.
19 . The case for the secondary battery as claimed in claim 18 , wherein 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 has 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.
20 . The case for the secondary battery as claimed in claim 19 , wherein the curved surface having the first radius of curvature is connected to at least one of the first side surface or the second side surface, and wherein the curved surface having the second radius of curvature is connected to at least one of the third side surface or the fourth side surface.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority to and the benefit of Korean Patent Application No. 10-2024-0155094, filed on Nov. 5, 2024, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated by reference herein. BACKGROUND 1. Field Aspects of embodiments of the present disclosure relate to a secondary battery, and a case for the 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 disclosure, and therefore, it may contain information that does not constitute related (or prior) art. SUMMARY Embodiments of the present disclosure may be directed to a secondary battery, and a case for the secondary battery. These and other aspects and features of the present disclosure will be described in or will be apparent from the following description of embodiments of the present disclosure. According to one or more embodiments of the present disclosure, 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