KR20220000636A - Secondary battery and device including the same - Google Patents

Abstract

A secondary battery according to an embodiment of the present invention includes: an electrode assembly impregnated with an electrolyte; a battery case for accommodating the electrode assembly and the electrolyte; a cap assembly coupled to the battery case; a gasket positioned between the battery case and the cap assembly; and a leakage preventing layer positioned between the battery case and the gasket, wherein a concave-convex structure is formed on a surface of the gasket facing the leakage preventing layer.

Description

Secondary battery and device including same {SECONDARY BATTERY AND DEVICE INCLUDING THE SAME}

The present invention relates to a secondary battery and a device including the same, and more particularly, to a secondary battery having improved sealing properties and a device including the same.

In recent years, the demand for portable electronic products such as laptops, video cameras, and mobile phones has rapidly increased, and as the development of electric vehicles, energy storage batteries, robots, satellites, etc. is in full swing, secondary batteries used as driving power A lot of research is being done about it.

The electrode assembly embedded in the battery case is a charging/discharging power generating element having a stacked structure of a positive electrode, a separator, and a negative electrode, and is classified into a jelly roll type, a stack type, and a stack/folding type. The jelly roll type is a form in which a separator is interposed between a long sheet-type positive electrode and a negative electrode coated with an active material, and the stack type is a form in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed therebetween, stack /Folding type is a composite structure of jelly-roll type and stack type. Among them, the jelly roll type electrode assembly has advantages of being easy to manufacture and having high energy density per weight.

According to the shape of the battery case, a cylindrical battery in which the electrode assembly is embedded in a cylindrical metal can, a prismatic battery in which the electrode assembly is embedded in a prismatic metal can, and the electrode assembly are embedded in a pouch-type case of an aluminum laminate sheet. It is classified as a pouch-type battery with Among them, the cylindrical battery has an advantage in that it has a relatively large capacity and is structurally stable.

Meanwhile, the secondary battery includes, for example, a nickel cadmium battery, a nickel hydrogen battery, a nickel zinc battery, and a lithium secondary battery. Among them, lithium secondary batteries are widely used in the field of advanced electronic devices because of their advantages of being free to charge and discharge, have a very low self-discharge rate, high operating voltage, and high energy density per unit weight because they do not have a memory effect compared to nickel-based secondary batteries. have.

1 is a partial cross-sectional view of an upper portion of a conventional cylindrical secondary battery.

Referring to FIG. 1 , a jelly roll-type electrode assembly 50 is accommodated in a cylindrical case 20 , and a cap assembly 30 is mounted on an open upper portion of the cylindrical case 20 to manufacture a cylindrical secondary battery 10 . can

The cap assembly 30 may include a top cap 31 and a safety vent 32 for internal pressure drop, and the top cap 31 and the safety vent 32 for internal pressure drop may form a structure in close contact with each other. .

The safety vent 32 may be electrically connected to the electrode assembly 50 through a current interrupt device (CID) 60 . The CID gasket 70 may surround the edge of the current blocking member 60 .

Meanwhile, in relation to the coupling of the cap assembly 30 and the cylindrical case 20 , a gasket 40 is positioned between the cap assembly 30 and the cylindrical case 20 , and then the cap assembly 30 and the cylindrical case 20 are coupled. The case 20 may be coupled by crimping. The crimping portion 22 may be formed in the cylindrical case 20 by the crimping coupling. Below the crimping part 22 , a beading part 21 in which a part of the cylindrical case 20 is recessed in the center direction of the electrode assembly 50 for stable coupling of the cap assembly 30 and preventing flow of the electrode assembly 50 . ) can be formed.

At this time, the gasket 40 is mounted on the inner surfaces of the crimping part 22 and the beading part 21 to increase the sealing force between the cap assembly 30 and the cylindrical case 20 . However, the electrolyte may leak through the gap between the crimping part 22 and the gasket 40 or the gap between the cap assembly 30 and the gasket 40 . The leaked electrolyte may cause corrosion of the upper surface of the secondary battery 10 , and may also cause a short circuit in the upper part of the secondary battery 10 .

Accordingly, there is a need to develop a cylindrical secondary battery capable of discharging gas generated in the activation process that can prevent electrolyte from leaking through a gap formed on the upper part of the secondary battery.

SUMMARY OF THE INVENTION An object of the present invention is to provide a secondary battery capable of preventing leakage of electrolyte through a gap formed on an upper portion of the secondary battery, and a device including the same.

However, the problems to be solved by the embodiments of the present invention are not limited to the above problems and may be variously expanded within the scope of the technical idea included in the present invention.

A secondary battery according to an embodiment of the present invention includes an electrode assembly impregnated with an electrolyte; a battery case accommodating the electrode assembly and the electrolyte; a cap assembly coupled to the battery case; a gasket positioned between the battery case and the cap assembly; and a leak prevention layer positioned between the battery case and the gasket, wherein a concave-convex structure is formed on a surface of the gasket facing the leak prevention layer.

The battery case and the cap assembly may be coupled by crimping with the gasket interposed therebetween, so that a crimping part may be formed in the battery case.

The leak prevention layer may be positioned between the crimping part and the gasket.

The leak prevention layer may seal a gap between the battery case and the gasket.

The secondary battery may further include a leak prevention layer positioned between the cap assembly and the gasket.

The secondary battery may further include a cover layer covering a gap between each of the battery case, the gasket, and the cap assembly on an upper portion of the cap assembly.

The concave-convex structure may include a plurality of depressions.

The depression may form a recessed structure and be distributed over the entire surface of the gasket facing the leak prevention layer.

The leak prevention layer may be formed by applying a liquid gasket to the inner surface of the battery case.

According to embodiments of the present invention, by providing a leak prevention layer in the gap formed on the upper portion of the secondary battery, it is possible to minimize the leakage of the electrolyte. Accordingly, it is possible to prevent problems such as corrosion of the upper surface of the secondary battery or a short circuit in the upper part of the secondary battery.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a partial cross-sectional view of an upper portion of a conventional cylindrical secondary battery.
2 is a perspective view of a secondary battery according to an embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing a portion of the cross-section taken along the cutting line A-A' of FIG. 2 .
4 is a partial cross-sectional view showing an enlarged portion "B" of FIG.
5 is a perspective view of a gasket according to an embodiment of the present invention.
6 is a partial cross-sectional view for explaining a leak prevention layer according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention may be embodied in several different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated.

Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference part means to be located above or below the reference part, and to necessarily mean to be located "on" or "on" in the direction opposite to gravity no.

In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, throughout the specification, when referring to "planar", it means when the target part is viewed from above, and "cross-sectional" means when viewed from the side when a cross-section of the target part is vertically cut.

2 is a perspective view of a secondary battery according to an embodiment of the present invention, FIG. 3 is a partial cross-sectional view showing a part of a cross section taken along the cutting line A-A' of FIG. 2, FIG. 4 is FIG. 3 It is a partial cross-sectional view showing the enlarged “B” part of Fig.

2 to 4 , the secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 500 impregnated with an electrolyte solution, an electrode assembly 500 and a battery case 200 for accommodating the electrolyte solution, and a battery. The cap assembly 300 coupled to the case 200 , the gasket 400 positioned between the battery case 200 and the cap assembly 300 , and a leak prevention layer positioned between the battery case 200 and the gasket 400 . (600).

First, the electrode assembly 500 has a structure in the form of a jelly roll wound with a separator 530 interposed between the positive electrode 510 and the negative electrode 520 , and a center pin (not shown) may be inserted into the center thereof. The center pin is generally made of a metal material to give a predetermined strength, and has a hollow cylindrical structure in which a plate is bent in a round shape. The center pin may act as a passage for fixing and supporting the electrode assembly 500 and for discharging gas generated by an internal reaction during charging, discharging, and operation. In particular, the gas generated in the activation process, which will be described later, may move.

The cap assembly 300 includes a top cap 310 and a safety vent 320 , and the top cap 310 is located on the safety vent 320 , and forms a structure in close contact with the safety vent 320 . can be electrically connected. The top cap 310 has a center that protrudes upward, and is indirectly connected to the positive electrode 510 of the electrode assembly 500 through a positive electrode tab 511 and the like, and functions as a positive electrode terminal by connection with an external circuit. can

The battery case 200 may have a cylindrical shape and may include a beading part 210 and a crimping part 220 .

The beading part 210 refers to a portion in which a part of the battery case 200 is recessed in the center direction of the electrode assembly 500 , for stable coupling of the cap assembly 300 and preventing flow of the electrode assembly 500 . will be. Here, the central direction of the electrode assembly 500 may mean a radial direction from the outer peripheral surface of the jelly roll-shaped electrode assembly 500 to the center.

The crimping part 220 is located above the beading part 210 and refers to a part surrounding the cap assembly 300 , and is for stable coupling of the cap assembly 300 . Specifically, the battery case 200 and the cap assembly 300 are crimped with the gasket 400 interposed therebetween, so that the crimping part 220 may be formed in the battery case 200 . That is, by placing the gasket 400 between the battery case 200 and the cap assembly 300 , and bending the end of the battery case 200 , the crimping part 220 is formed. Through this, the cap assembly 300 may be mounted and the secondary battery 100 may be sealed. The gasket 400 is mounted on the inner surfaces of the crimping part 220 and the beading part 210 to increase the sealing force between the cap assembly 300 and the battery case 200 .

On the other hand, under the safety vent 320, a current blocking member 700 (Current Interrupt Device, CID) and the CID gasket 800 may be located. The safety vent 320 is a thin film structure through which current flows, and two indentations 321 and 322 having different depths may be formed therein.

The current blocking member 700 is a member of a conductive plate material, and may include an outer peripheral portion 710 and a blocking portion 720 surrounded by the outer peripheral portion 710 . Also, although not specifically illustrated, a plurality of through holes for discharging gas may be formed. In an abnormal operating situation, when the pressure inside the secondary battery 100 rises, the blocking part 720 is separated from the outer peripheral part 710 , and the electrical connection between the external circuit and the electrode assembly 500 may be blocked.

The CID gasket 800 is a member surrounding the edge of the current blocking member 700 , and may prevent the safety vent 320 from coming into contact with the outer peripheral portion 710 .

As described above, the leak prevention layer 600 is located between the battery case 200 and the gasket 400 , and more specifically, it is located between the crimping part 220 and the gasket 400 of the battery case 200 . can Also, it may extend between the beading part 210 of the battery case 200 and the gasket 400 .

In the case of the conventional secondary battery 10 shown in FIG. 1 , the electrolyte is often leaked through the gap between the crimping part 22 and the gasket 40 , and the leaked electrolyte prevents corrosion of the upper surface of the secondary battery 10 . It may cause, and may also cause a short circuit in the upper part of the secondary battery 10 .

On the other hand, in the secondary battery 100 according to the present embodiment, the leakage preventing layer 600 is formed to fill the gap between the crimping unit 220 and the gasket 400 , thereby preventing the electrolyte from leaking into the gap therebetween. . That is, the leak prevention layer 600 according to the present embodiment may seal the gap between the battery case 200 and the gasket 400 .

The leak prevention layer 600 may be formed by applying a liquid gasket to a region corresponding to the portion where the crimping portion 220 and the beading portion 210 are to be formed on the inner surface of the battery case 200 . Liquid gasketing is a material that is applied in a liquid phase and solidifies after sealing the gap, and can effectively seal even gaps that cannot be filled with the existing solid gasket 400 alone. The liquid gasket agent may include a silicon-based material.

5 is a perspective view of a gasket according to an embodiment of the present invention. Specifically, the gasket 400 included in the secondary battery of FIGS. 3 and 4 is shown in a perspective view.

4 and 5 , in the gasket 400 according to the present embodiment, a concave-convex structure may be formed on a surface facing the leakage preventing layer 600 . Specifically, the concave-convex structure formed by the gasket 400 may form a surface having repeated curvature of concave and convex. For example, the plurality of depressions 410 may be positioned at regular intervals to form the concave-convex structure. Specifically, the depressions 410 may form a recessed structure and may be positioned at regular intervals from each other, and may be distributed over the entire surface of the gasket 400 facing the leak prevention layer 600 .

As described above, even when the leak prevention layer 600 is formed to prevent leakage of the electrolyte, the liquid gasket agent may not be evenly coated on the inner surface of the battery case 200 due to the characteristics of the liquid gasket agent. In this case, a portion where the leakage prevention layer 600 is not properly formed may occur, and the electrolyte may leak into this portion, which is not effective in preventing leakage of the electrolyte. Accordingly, in the gasket 400 according to the present embodiment, the concave-convex structure is formed on the surface facing the leak prevention layer 600 to secure the application of a liquid gasket agent to all areas. That is, according to the present embodiment, the leak prevention layer 600 is evenly distributed between the gasket 400 and the battery case 200 through the uneven structure.

6 is a partial cross-sectional view for explaining a gasket and a leak prevention layer according to another embodiment of the present invention.

Referring to FIG. 6 , the leak prevention layer 600 according to another embodiment of the present invention may be formed not only between the battery case 200 and the gasket 400 , but also between the cap assembly 300 and the gasket 400 . can Specifically, the liquid gasket is applied between the cap assembly 300 and the gasket 400 before the crimping portion 220 is formed by crimping bonding, and then the crimping is performed to form an additional leak prevention layer ( 600) can be formed.

In addition, in the gasket 400 according to the present embodiment, a concave-convex structure may be formed on a surface facing the leak prevention layer 600 located between the cap assembly 300 and the gasket 400 , for example, a plurality of depressions. 410 may be positioned at regular intervals to form the concave-convex structure. That is, the uneven structure may be formed on the inner surface as well as the outer surface of the gasket 400 .

Electrolyte may also leak through the gap between the gasket 400 and the cap assembly 300 . According to the present embodiment, the gap may be filled by forming the additional leak prevention layer 600 . In addition, by forming the concave-convex structure such as the plurality of depressions 410 on the inner surface of the gasket, the leakage preventing layer 600 may be evenly distributed.

Meanwhile, the secondary battery according to the present embodiment further includes a cover layer 610 covering a gap between each of the battery case 200 , the gasket 400 , and the cap assembly 300 at the top of the cap assembly 300 . can do. Specifically, the leak prevention layer 600 positioned between the battery case 200 and the gasket 400 or between the cap assembly 300 and the gasket 400 may extend to form the cover layer 610 . That is, with respect to the secondary battery in which the coupling of the cap assembly 300 is completed, a gap between the battery case 200 and the gasket 400 exposed on the upper portion of the cap assembly 300 or the cap assembly 300 and the gasket 400 ) The cover layer 610 according to the present embodiment may be formed by applying a liquid gasket to cover all the gaps therebetween. By additionally blocking the leakage path of the electrolyte through the cover layer 610, the sealing property of the secondary battery can be further increased.

In this embodiment, terms indicating directions such as front, rear, left, right, up, and down are used, but these terms are for convenience of explanation only, and may vary depending on the location of the object or the position of the observer. .

The secondary battery according to the present embodiment described above can be applied to various devices. Specifically, it may be applied to transportation means such as an electric bicycle, an electric vehicle, a hybrid, etc., but is not limited thereto and may be applied to various devices that can use a secondary battery.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

100: secondary battery
200: battery case
300: cap assembly
400: gasket
500: electrode assembly
600: leak-proof layer

Claims (10)

an electrode assembly immersed in an electrolyte;
a battery case accommodating the electrode assembly and the electrolyte;
a cap assembly coupled to the battery case;
a gasket positioned between the battery case and the cap assembly; and
and a leak prevention layer positioned between the battery case and the gasket,
A secondary battery in which a concave-convex structure is formed on a surface of the gasket facing the leak prevention layer. In claim 1,
A secondary battery in which the battery case and the cap assembly are coupled by crimping with the gasket interposed therebetween to form a crimping part in the battery case. In claim 2,
The leak prevention layer is a secondary battery located between the crimping part and the gasket. In claim 1,
The leak prevention layer is a secondary battery that seals a gap between the battery case and the gasket. In claim 1,
The secondary battery further comprising a leak prevention layer positioned between the cap assembly and the gasket. In claim 1,
The secondary battery further comprising a cover layer on an upper portion of the cap assembly to cover a gap between each of the battery case, the gasket, and the cap assembly. In claim 1,
The concave-convex structure is a secondary battery including a plurality of depressions. In claim 7,
The recessed portion forms a recessed structure and is distributed over the entire surface of the gasket facing the leakage preventing layer. In claim 1,
The leak prevention layer is a secondary battery formed by applying a liquid gasketing agent (Liquid Gasketing) on the inner surface of the battery case. A device comprising the secondary battery according to claim 1 .

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