Secondary battery and method for manufacturing the same

Abstract

The present invention relates to a secondary battery having a simplified cover assembly structure to secure an internal space and thus can have an increased capacity. In one embodiment, a secondary battery is disclosed, the secondary battery including: an electrode assembly; a case for accommodating the electrode assembly; and a cover assembly coupled to a top of the case and electrically connected to the electrode assembly, wherein the cover assembly includes a cover plate having an annular first recess formed on an upper surface of the cover plate and an annular second recess formed on a lower surface of the cover plate and connected to the first recess, and an insulating member insert-molded into the first recess.

Description

Technical Field

[0001] This invention relates to a secondary battery. Background Technology

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are rechargeable and dischargeable. Low-capacity secondary batteries can be used in various portable small electronic devices (such as smartphones, feature phones, laptops, digital cameras, or camcorders), while high-capacity secondary batteries are widely used as power sources for motor drives (such as those in hybrid or electric vehicles). These lithium-ion secondary batteries can be classified by shape as cylindrical, prismatic, and pouch-type secondary batteries.

[0003] Specifically, a cylindrical lithium secondary battery typically includes a cylindrical electrode assembly, a cylindrical housing to which the electrode assembly is attached, an electrolyte injected into the housing to allow the movement of lithium ions, and a cap assembly attached to one side of the housing to prevent leakage of the electrolyte solution and to prevent separation of the electrode assembly.

[0004] The information disclosed above in this background section is only intended to enhance the understanding of the background of the invention, and therefore may include information that does not constitute prior art. Summary of the Invention

[0005] Technical issues

[0006] The present invention provides a secondary battery with a simplified cover assembly structure to ensure internal space and thus allow for increased capacity.

[0007] Technical solution

[0008] The secondary battery according to the present invention may include: an electrode assembly; a housing for receiving the electrode assembly; and a cover assembly coupled to the top of the housing and electrically connected to the electrode assembly, wherein the cover assembly includes a cover plate and an insulating member inserted into a first groove, the cover plate having an annular first groove formed on an upper surface of the cover plate and an annular second groove formed on a lower surface of the cover plate and connected to the first groove.

[0009] The cover may include a terminal area located inside the insulating member and a main board located outside the insulating member.

[0010] The electrode terminals of the electrode assembly can be connected to the terminal area.

[0011] The protruding groove can be formed on the inner and outer walls of the first groove in the horizontal direction.

[0012] Insulating components may include protrusions that engage with protruding grooves.

[0013] The cover plate may also include a hole formed outside the first groove and an exhaust plate covering the hole.

[0014] The second groove can expose the lower surface of the insulating component.

[0015] The method for manufacturing a secondary battery according to the present invention may include the following steps: forming an annular first groove on the upper surface of a cover plate; molding an insulating member insert into the first groove; and forming an annular second groove connected to the first groove on the lower surface of the cover plate.

[0016] The lower surface of the insulating member can be exposed through the second groove, and the cover plate may include a terminal area located inside the insulating member and a main board located outside the insulating member.

[0017] In the step of forming the first groove, protruding grooves can be formed on the inner and outer walls of the first groove in the horizontal direction.

[0018] Insulating components may include protrusions that fill protruding grooves.

[0019] The method may also include forming a hole outside the first groove and forming an exhaust plate covering the hole.

[0020] Beneficial effects

[0021] The secondary battery according to an embodiment of the invention includes a cover plate in which an insulating member insert is molded, and thus has a simplified cover assembly structure to save costs and ensure internal space to increase the capacity of the secondary battery. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

[0023] Figure 2 This is a plan view showing a cover assembly according to an embodiment of the present invention.

[0024] Figure 3 This is a cross-sectional view showing a cover assembly according to an embodiment of the present invention.

[0025] Figures 4a to 4d This is a cross-sectional view illustrating a method for manufacturing a cover assembly according to an embodiment of the present invention. Detailed Implementation

[0026] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Examples of the invention are provided to explain it more fully to those skilled in the art, and the following examples can be modified in various other forms. However, the invention can be embodied in many different forms and should not be construed as limited to the examples (or exemplary) embodiments set forth herein. Rather, these exemplary embodiments are provided so that the invention will be thorough and complete, and will convey aspects and features of the invention to those skilled in the art.

[0028] Additionally, for the sake of brevity and clarity, the dimensions or thicknesses of various components are exaggerated in the accompanying drawings. The same reference numerals always refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. Furthermore, it will be understood that when element A is referred to as being "connected to" element B, element A may be directly connected to element B, or an intermediary element C may exist between element A and element B, such that element A and element B are indirectly connected to each other.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It will also be understood that, when used in this specification, the terms "comprising or including" and / or variations thereof indicate the presence of the stated features, quantities, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, and / or groups thereof.

[0030] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “above” may be used herein to describe the relationship between one element or feature as shown in the accompanying drawings and another (other) element or feature. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation other than those depicted in the accompanying drawings. For example, if an element or feature in the accompanying drawings is flipped, an element described as “below” or “under” another element or feature would then be positioned “above” or “above” said other element or feature. Thus, the exemplary term “below” can cover both above and below orientations.

[0031] Figure 1 This is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

[0032] Reference Figure 1 According to an embodiment of the present invention, the secondary battery 100 may include an electrode assembly 110, a housing 120, and a cover assembly 150.

[0033] The electrode assembly 110 includes a first electrode 111, a second electrode 112, and a diaphragm 113 disposed between the first electrode 111 and the second electrode 112. The electrode assembly 110 can be formed by winding a laminate of the first electrode 111, the diaphragm 113, and the second electrode 112 into a jelly roll shape. Here, the first electrode 111 can be used as a positive electrode, and the second electrode 112 can be used as a negative electrode. A first electrode tab 114 is formed on the upper part of the electrode assembly 110 and connected to the cover assembly 150, and a second electrode tab 115 is formed on the lower part of the electrode assembly 110 and connected to the lower plate 122 of the housing 120.

[0034] The first electrode 111 is formed by applying a first electrode active material, such as a transition metal oxide, to a first electrode current collector formed of a metal foil, such as aluminum. A first electrode uncoated portion, to which the first electrode active material is not applied, is formed on the first electrode 111, and a first electrode tab 114 is attached to the first electrode uncoated portion. One end of the first electrode tab 114 is electrically connected to the first electrode 111, and the other end protrudes upward from the electrode assembly 110 and is electrically connected to the cover assembly 150.

[0035] The second electrode 112 is formed by applying a second electrode active material, such as graphite or carbon, onto a second electrode current collector formed of a metal foil, such as copper or nickel. A second electrode uncoated portion, to which the second electrode active material is not applied, is formed on the second electrode 112, and a second electrode tab 115 is attached to the second electrode uncoated portion. One end of the second electrode tab 115 is electrically connected to the second electrode 112, and the other end protrudes downward from the electrode assembly 110 and is electrically connected to the lower plate 122 of the housing 120.

[0036] A separator 113 is positioned between the first electrode 111 and the second electrode 112 to prevent short circuits and allow lithium ions to move. The separator 113 may be made of polyethylene (PE), polypropylene (PP), or a composite membrane of polyethylene (PE) and polypropylene (PP).

[0037] The housing 120 includes a side plate 121 and a lower plate 122. The side plate 121 is a cylinder with a certain diameter to form a space therein for accommodating the electrode assembly 110. The lower plate 122 seals the lower part of the side plate 121. In some examples, the housing 120 may be referred to as a cylindrical can. The top opening of the housing 120 is open to be sealed after the electrode assembly 110 is inserted into the housing 120. Additionally, a stepped portion 123 on which a cover assembly 150 is disposed may be formed at the upper end of the housing 120. The stepped portion 123 may be a groove formed on the inner surface of the housing 120. After the cover assembly 150 is disposed on the stepped portion 123, the boundary between the housing 120 and the cover assembly 150 is welded so that the housing 120 can be sealed. A second electrode connector 115 may be electrically connected to the lower plate 122 of the housing 120. Therefore, the housing 120 may have the same polarity as the second electrode 112.

[0038] Figure 2 This is a plan view showing a cover assembly according to an embodiment of the present invention. Figure 3 This is a cross-sectional view showing a cover assembly according to an embodiment of the present invention.

[0039] Reference Figure 2 and Figure 3 The cover assembly 150 may include a cover plate 130 and an insulating member 140.

[0040] The cover plate 130 may include a main board 131 and a terminal area 132 located inside the main board 131. The main board 131 and the terminal area 132 may be electrically separated from each other by an insulating member 140.

[0041] The motherboard 131 can be attached to the stepped portion 123 of the housing 120. The thickness of the motherboard 131 can be formed to be the same as the height of the stepped portion 123. Therefore, the upper surface of the motherboard 131 and the top of the housing 120 can be on the same plane. The housing 120 can be sealed by welding the interface between the motherboard 131 and the housing 120. In some examples, the motherboard 131 can have the same polarity as the housing 120 and the second electrode 112.

[0042] Terminal region 132 is located at the center of cover plate 130 and can be electrically separated from main board 131 via insulating member 140. Terminal region 132 can be electrically connected to first electrode tab 114. In some examples, the first electrode tab 114, which protrudes upward from electrode assembly 110, can be soldered to the lower surface of terminal region 132. Therefore, terminal region 132 can have the same polarity as the first electrode 111.

[0043] The cover plate 130 may include a first groove 133 formed on the top of the cover plate 130 and a second groove 135 formed on the bottom of the first groove 133, located between the terminal region 132 and the main board 131. The first groove 133 and the second groove 135 may be connected to each other to form a hole penetrating the cover plate 130. To electrically decouple the terminal region 132 and the main board 131, the first groove 133 and the second groove 135 may be formed in an annular shape that surrounds the terminal region 132 and penetrates the cover plate 130. An insulating member 140 is attached to the first groove 133 and prevents the main board 131 and the terminal region 132 from separating. The inner wall of the first groove 133 may form the outer wall of the terminal region 132, and the outer wall of the first groove 133 may form the inner wall of the main board 131. A protruding groove 133a is formed horizontally on the inner and outer walls of the first groove 133, thereby securing the insulating member 140 attached to the first groove 133 to prevent it from falling out of the cover plate 130. The protruding groove 133a can be formed as a ring extending along the inner and outer walls, respectively. In the accompanying drawings, the cross-section of the protruding groove 133a is shown as triangular, but the protruding groove 133a can be applied in any shape as long as it extends outward from the first groove 133. For example, the cross-section of the protruding groove 133a can be formed in various shapes, including semicircles, rectangles, inverted triangles, etc.

[0044] The second groove 135 is formed at a position corresponding to the first groove 133. The height of the second groove 135 may be less than the height of the first groove 133. Since the insulating member 140 connecting the terminal area 132 and the main board 131 is incorporated into the first groove 133, the height of the first groove 133 is preferably higher than the height of the second groove 135. The sum of the heights of the first groove 133 and the second groove 135 may be equal to the height of the cover plate 130. In addition, the width of the second groove 135 may be greater than the width of the first groove 133.

[0045] The cover plate 130 may include a hole 134 formed on one side of the main board 131 and a vent plate 136 coupled to the hole 134. The vent plate 136 may be formed to have a thickness less than that of the main board 131 and may have a notch 136a formed therein to open under a set pressure. In some examples, when the pressure inside the housing 120 exceeds the set pressure due to overcharging of the secondary battery 100, the notch 136a ruptures and the gas inside the housing 120 is released to the outside, thereby preventing the secondary battery 100 from catching fire or exploding.

[0046] The insulating member 140 can be incorporated into the first recess 133 of the cover plate 130. The insulating member 140 can be insert-formed into the first recess 133 to insulate the terminal region 132 and the main board 131 from each other, and simultaneously allow the terminal region 132 and the main board 131 to be combined so as not to separate. In some examples, after the insert is formed into the first recess 133 of the cover plate 130, the insulating member 140 can insulate the terminal region 132 and the main board 131 from each other by exposing a second recess 135 at the lower part of the insulating member 140. Alternatively, the insulating member 140 can be formed as a ring corresponding to the first recess 133.

[0047] The insulating member 140 may include a protrusion 141 that engages with the protruding recess 133a. The protrusion 141 is formed to project from both the inner and outer surfaces of the insulating member 140 and may engage with the protruding recess 133a of the first recess 133. In some examples, the insulating member 140 may include a heat-resistant resin. For example, the insulating member 140 may include polypropylene (PP), polyethylene (PE), or perfluoroalkoxy (PFA).

[0048] As described above, in this invention, unlike conventional cylindrical secondary batteries where the cover assembly is joined to the housing by forming a rolled edge and a press-fit portion in the housing, the cover assembly 150 is directly welded to the housing 120, thereby preventing deformation of the cover assembly 150. Furthermore, the cover assembly 150 of this invention includes a cover plate 130 in which an insulating member 140 is embedded, thus allowing for a simplified structure to reduce costs and ensuring sufficient internal space to increase the capacity per unit volume of the secondary battery 100.

[0049] Figures 4a to 4d This is a cross-sectional view illustrating a method for manufacturing a cover assembly according to an embodiment of the present invention.

[0050] Reference Figures 4a to 4d A method for manufacturing a cover assembly 150 according to an embodiment of the present invention is described.

[0051] like Figure 4aAs shown, an annular first groove 133 is formed on the top of the cover plate 130, and a hole 134 penetrating the cover plate 130 is formed outside the first groove 133. The first groove 133 is formed in an annular shape that does not penetrate the cover plate 130, such that a relatively thin bottom surface 133b exists below the first groove 133. The cover plate 130 can be divided into a main plate 131 positioned outside the first groove 133 and an inner region 132' positioned inside the first groove 133. The main plate 131 and the inner region 132' are connected by the bottom surface 133b. The inner region 132' can become a terminal region 132 by separating from the main plate 131 via a second groove 135 in the process described later. Protruding grooves 133a are formed on the inner and outer walls of the first groove 133. The hole 134 is formed in the main plate 131 and can serve as a channel for the internal gas to be discharged through it.

[0052] like Figure 4b As shown, the insulating member 140 can be inserted into the first recess 133. The insulating member 140 can be placed on the bottom surface 133b located below the first recess 133. Additionally, the insulating member 140 may include a protrusion 141 corresponding to a protruding recess 133a. In some examples, when the insulating member 140 is inserted into the first recess 133, the protrusion 141 can be formed by partially filling the protruding recess 133a of the first recess 133. The protrusion 141 may protrude from both the inner and outer surfaces of the insulating member 140.

[0053] like Figure 4c As shown, a second groove 135 can be formed below the first groove 133 to form a terminal region 132 separate from the motherboard 131. The second groove 135 can be formed on the portion corresponding to the first groove 133 (i.e., on the bottom surface 133b) to expose the lower surface of the insulating member 140. Additionally, the second groove 135 can electrically separate the inner region 132' from the motherboard 131 to form the terminal region 132. In some examples, the second groove 135 can be formed to be wider than the width of the first groove 133.

[0054] like Figure 4d As shown, an exhaust plate 136 can be formed in the hole 134. The exhaust plate 136 covers the hole 134 and can be soldered to the main board 131. In addition, a rupture groove is formed in the exhaust plate 136, which ruptures when internal gas is generated, thereby releasing the internal gas.

[0055] Subsequently, the cover assembly 150 can be soldered to the first electrode tab 114 of the electrode assembly 110 housed inside the housing 120. The first electrode tab 114 can be soldered to the terminal region 132 of the cover plate 130. The cover assembly 150 can be mounted on the stepped portion 123 of the housing 120 and then soldered to the housing 120.

[0056] While the foregoing embodiments have been provided for implementing the secondary battery according to the invention, it should be understood that the embodiments described herein should be considered only in a descriptive sense and not for limiting purposes, and various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

[0057] Industrial applicability

[0058] This invention relates to a secondary battery.

Claims

1. A secondary battery, the secondary battery comprising: Electrode assembly; A housing for accommodating the electrode assembly; as well as The cover assembly is attached to the top of the housing and electrically connected to the electrode assembly. The cover assembly includes: a cover plate having an annular first groove formed on the upper surface of the cover plate and an annular second groove formed on the lower surface of the cover plate and connected to the first groove; and an insulating member, an insert formed into the first groove. The insulating member is formed as an annular shape corresponding to the first groove, and The second groove exposes the lower surface of the insulating member.

2. The secondary battery according to claim 1, wherein, The cover plate includes a terminal area located inside the insulating member and a main board located outside the insulating member.

3. The secondary battery according to claim 2, wherein, The electrode terminals of the electrode assembly are connected to the terminal area.

4. The secondary battery according to claim 1, wherein, The protruding grooves are formed horizontally on the inner and outer walls of the first groove.

5. The secondary battery according to claim 4, wherein, The insulating member includes a protrusion that engages with the protruding groove.

6. The secondary battery according to claim 1, wherein, The cover plate also includes a hole formed outside the first groove and an exhaust plate covering the hole.

7. A method for manufacturing a secondary battery, the method comprising the following steps: An annular first groove is formed on the upper surface of the cover plate; The insulating component insert is molded into the first groove; as well as An annular second groove, connected to the first groove, is formed on the lower surface of the cover plate, and the second groove exposes the lower surface of the insulating member. The insulating member is formed as a ring corresponding to the first groove.

8. The method according to claim 7, wherein, The cover plate includes a terminal area located inside the insulating member and a main board located outside the insulating member.

9. The method according to claim 7, wherein, In the step of forming the first groove, protruding grooves are formed in the horizontal direction on the inner and outer walls of the first groove.

10. The method according to claim 9, wherein, The insulating member includes protrusions that fill the protruding groove.

11. The method of claim 7, further comprising forming a hole outside the first groove and forming an exhaust plate covering the hole.

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