KR20210155528A - 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; a battery case accommodating the electrode assembly and having a passage unit for discharging gas; and a block formed on the battery case to control opening and closing of the passage unit. One side of the passage unit is connected to a discharge hole opened to the outside of the battery case, and the other side of the passage unit is connected to an inlet hole. Depending on the internal pressure of the battery case, the inlet hole is blocked by the block or connected to the inside of the battery case, so that discharge of the gas through the passage unit is controlled.

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 safety against high-temperature and high-pressure environments 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.

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.

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.

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.

However, when a lithium secondary battery is exposed to high temperatures or a large current flows within a short time due to overcharging, external short circuit, needle penetration, local damage, etc., there is a risk of explosion as the battery is heated by IR heat. In other words, when the pressure or temperature of the battery increases, the decomposition reaction of the active material and a number of side reactions proceed, and accordingly, the temperature of the battery rises rapidly, which in turn accelerates the reaction between the electrolyte and the electrode. Eventually, a thermal runaway phenomenon occurs in which the temperature of the battery rapidly rises, and when the temperature rises above a certain level, the battery may ignite, and the lithium secondary battery explodes due to the increased internal pressure of the battery.

Therefore, when the lithium secondary battery is placed in an abnormal operating state such as high temperature, high pressure, etc., various methods are being discussed to effectively control it. As part of an effort to secure safety, there are a method of mounting a device outside the cell and a method of using a material inside the cell. A safety vent using a change in internal voltage of the cell corresponds to the former.

Hereinafter, a safety vent structure in a conventional secondary battery will be described with reference to FIG. 1 .

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 .

During normal operation, the upper cap 31 functions as a positive electrode terminal, but when the internal pressure of the cylindrical secondary battery 10 rises, the current blocking member 60 is separated to separate the upper cap 31 and the electrode assembly 50 between the upper cap 31 and the electrode assembly 50 . cut off the current In this way, it was attempted to secure safety by blocking the current of the current blocking member 60 according to the increase of the withstand pressure. However, in this method, the gas inside the cylindrical secondary battery 10 is not directly discharged. As described above, the cylindrical secondary battery 10 is manufactured by inserting the electrode assembly 50 into the cylindrical case 20 , coupling the cap assembly 30 , and then sealing it. Since it is sealed, it is difficult to discharge the gas produced by the reaction occurring inside the cylindrical secondary battery 10 . Accordingly, even when the current blocking member 60 operates, ignition may occur when the internal temperature continuously rises, and the increased internal pressure is not resolved, which may lead to explosion. This is one of the factors impairing the safety of the cylindrical secondary battery 10 .

In the case of the pouch-type case of the laminate sheet, when gas is generated from the inside, the junction of the pouch-type case may open and the gas inside may be discharged. That is, unlike the cylindrical secondary battery 10, the internal gas can be easily discharged.

Accordingly, there is a need for development of a cylindrical or prismatic battery capable of effectively discharging internal gas when placed in an abnormal operating state.

An object of the present invention is to provide a secondary battery capable of automatically discharging internal gas according to an increase in internal pressure 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; a battery case accommodating the electrode assembly and having a passage portion for discharging gas; and a block formed on the battery case to control opening and closing of the passage. One side of the passage part is connected to the discharge hole opened to the outside of the battery case, and the other side of the passage part is connected to the inflow hole. Depending on the internal pressure of the battery case, the inlet hole is blocked by the block or connected to the inside of the battery case, so that the gas discharge through the passage is controlled.

The secondary battery may further include a spring member positioned on a surface of the block facing the electrode assembly and opposite to the surface of the block.

According to the internal pressure of the battery case and the elastic force of the spring member, the block may move, and gas discharge through the passage may be controlled.

During normal operation, the inlet hole is blocked in the block, and when the internal pressure of the battery case rises, the block moves and the passage portion is connected to the inside of the battery case through the inlet hole, so that the gas inside the battery case is discharged from the outside can be emitted as

A connection passage part may be formed in the block, one side of the connection passage part may be connected to a first connection hole opened to the inside of the battery case, and the other side of the connection passage part may be connected to a second connection hole.

During normal operation, the second connection hole may be displaced from the inlet hole, and when the internal pressure of the battery case rises, the block may move so that the second connection hole and the inlet hole are connected to each other.

An opening direction of the inlet hole and an opening direction of the discharge hole may be perpendicular to each other, and an opening direction of the first connection hole and an opening direction of the second connection hole may be perpendicular to each other.

The block may be mounted in a recess of a structure recessed from the inner surface of the battery case.

The inlet hole may be formed in the indentation.

During normal operation, the inlet hole may be blocked by the block, and when the internal pressure of the battery case increases, the block may move to expose the inlet hole to the inside of the battery case.

The block and the passage portion may be formed in a bottom portion of the battery case.

According to embodiments of the present invention, by forming a passage structure in the battery case that automatically opens and closes according to the internal pressure of the battery case, it is possible to effectively discharge the gas inside the secondary battery. That is, by automatically discharging gas generated in abnormal operating conditions such as high temperature, high pressure, or internal short circuit, ignition or explosion of the secondary battery can be prevented.

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 cross-sectional perspective view of a secondary battery according to an embodiment of the present invention.
3 and 4 are partial cross-sectional views showing an enlarged portion “A” of FIG. 2 .
5 and 6 are partial cross-sectional views for explaining a block structure 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 cross-sectional perspective view of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 2 , the secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 200 and a battery case 300 accommodating the electrode assembly 200 . More specifically, the electrode assembly 200 may be impregnated with an electrolyte to be accommodated in the battery case 300 , and the cap assembly 400 is coupled to the open upper portion of the battery case 300 to seal the secondary battery 100 . can be manufactured.

The electrode assembly 200 may have a structure in the form of a jelly roll wound with a separator 230 interposed between the long sheet-shaped positive electrode 210 and the negative electrode 220 .

The cap assembly 400 includes a top cap 410 and a safety vent 420 , and the top cap 410 is located on the safety vent 420 , and forms a structure in close contact with the safety vent 420 . to be electrically connected. The top cap 410 has a center that protrudes upward, and is directly or indirectly connected to the positive electrode 210 of the electrode assembly 200 through a positive electrode tab, etc., so as to function as a positive electrode terminal by connection with an external circuit. have.

The battery case 300 may be a metal can having a cylindrical shape including a bottom part 330, and may include a beading part 340 and a crimping part 350 combined with crimping. have.

The beading part 340 refers to a portion in which a part of the battery case 300 is recessed in the center direction of the electrode assembly 200 , and is used for stable coupling of the cap assembly 400 and preventing flow of the electrode assembly 200 . will be. Here, the central direction of the electrode assembly 200 means a radial direction from the outer peripheral surface of the jelly roll-shaped electrode assembly 200 to the center.

The crimping part 350 is located above the beading part 340 and refers to a part surrounding the cap assembly 400 , and is for stable coupling of the cap assembly 400 . Meanwhile, the cap assembly 400 may further include a gasket 430 for increasing sealing force. Specifically, the gasket 430 is mounted inside the crimping part 350 and the beading part 340 to increase the sealing force between the cap assembly 400 and the battery case 300 . That is, by placing the gasket 430 between the battery case 300 and the safety vent 420 , and bending the end of the battery case 300 , the crimping part 350 is formed. Through this, the cap assembly 400 can be mounted and the secondary battery 100 can be sealed.

Hereinafter, the gas exhaust structure according to the present embodiment will be described in detail with reference to FIGS. 3 and 4 .

3 and 4 are partial cross-sectional views illustrating an enlarged portion “A” of FIG. 2 , and partially enlarged views of the bottom part 330 of the battery case 300 of FIG. 2 . In particular, FIG. 3 shows a state during normal operation, and FIG. 4 shows a state during abnormal operation.

2 to 4 , the secondary battery 100 according to the present embodiment has an electrode assembly 200 and a battery case 300 in which a passage 310 for accommodating the electrode assembly 200 and discharging gas is formed. and a block 500 formed in the battery case 300 to control the opening and closing of the passage 310 . One side of the passage part 310 is connected to the discharge hole 311 opened to the outside of the battery case 300 , and the other side of the passage part 310 is connected to the inflow hole 312 . At this time, depending on the internal pressure of the battery case 300 , the inlet hole 312 is blocked by the block 500 or connected to the inside of the battery case 300 , so that the gas discharge through the passage 310 is controlled.

Specifically, the secondary battery 100 according to the present embodiment further includes a spring member 600 positioned on the surface facing the electrode assembly 200 accommodated in the battery case 300 and the surface opposite to the block 500 . can do. A connection passage part 510 may be formed in the block 500 , and one side of the connection passage part 510 may be connected to the first connection hole 511 opened to the inside of the battery case 300 , and the connection passage The other side of the part 510 may be connected to the second connection hole 512 . The block 500 and the spring member 600 may be mounted on the indentation portion 320 having a structure that is depressed from the inner surface of the battery case 300 . In this case, the inner surface of the battery case 300 means an inner surface facing the electrode assembly 200 with respect to the battery case 300 . On the other hand, the inlet hole 312 of the aforementioned passage portion 310 may be formed in the indentation portion 320 .

First, referring to FIG. 3 during normal operation, when the secondary battery according to the present embodiment operates normally, the inlet hole 312 of the passage part 310 is blocked by the block 500 . Specifically, the inflow hole 312 of the passage 310 and the second connection hole 512 of the connection passage 510 are shifted from each other. Accordingly, during normal operation, the secondary battery 100 is sealed without emitting gas.

Next, referring to FIG. 4 during abnormal operation, the internal pressure of the battery case 300 may be abnormally increased due to an internal short circuit due to a high temperature environment or impact. When the internal pressure of the battery case 300 rises, the block 500 may move so that the passage 310 may be connected to the inside of the battery case 300 through the inlet hole 312 . More specifically, when the internal pressure of the battery case 300 rises, the inlet hole 312 of the passage 310 that is displaced by the movement of the block 500 and the second connection hole 512 of the connection passage 510 are mutually can be connected Accordingly, in case of abnormal operation, a gas discharge path including the passage 310 and the connection passage 510 may be formed.

In relation to the movement of the block 500 , when the internal pressure of the battery case 300 rises above a certain level, the spring member 600 is compressed to move the block 500 . That is, according to the present embodiment, according to the internal pressure of the battery case 300 and the elastic force of the spring member 600 , the block 500 moves and gas discharge through the passage 310 can be adjusted, and the battery case (300) It is possible to implement a structure in which opening and closing is automatically adjusted according to the internal pressure. The spring constant, size, number, etc. of the spring member 600 may be set in consideration of the reference degree of the internal pressure for securing the safety of the secondary battery 100 .

Meanwhile, as shown in FIGS. 3 and 4 , the opening direction of the inlet hole 312 and the opening direction of the discharge hole 311 are perpendicular to each other, and the opening direction of the first connection hole 511 and the second connection hole ( 512) are preferably perpendicular to each other. In other words, it is preferable that the passage 310 and the connecting passage 510 each form a passage bent at least once. Through the above structure, the automatic opening and closing structure of the passage 310 and the connecting passage 510 according to the compression of the spring member 600 and the movement of the block 500 can be implemented.

In the secondary battery 100 according to the present embodiment, during normal operation, the sealing is maintained due to the coupling between the battery case 300 and the cap assembly 400 of the metal can, but in an abnormal operating state in which the internal pressure rises above a certain standard. The block 500 automatically moves by the internal pressure, and the passage 310 is opened to discharge gas. That is, it is possible to form a passage structure that automatically opens and closes according to the internal pressure of the battery case 300 , so that sealing and gas discharge can be adjusted according to the situation, and ultimately, ignition or explosion of the secondary battery 100 can be prevented. By blocking, it is possible to increase the safety of the secondary battery 100 .

On the other hand, there is no particular limitation on the positions of the block 500 and the passage part 310 according to the present embodiment, and the bottom part 330 of the battery case 300 , the side surface of the battery case 300 or the cap assembly 400 ) can be formed in However, it is preferable to form a thickness sufficient to arrange the block 500 and the passage portion 310 and to be formed on the bottom portion 330 of the battery case 300 in order to stably arrange the configuration. .

Hereinafter, with reference to FIGS. 5 and 6, a configuration of a block and a passage according to another embodiment of the present invention will be described.

5 and 6 are partial cross-sectional views for explaining a block structure according to another embodiment of the present invention. Specifically, similarly to FIGS. 3 and 4 , it is a partial cross-sectional view corresponding to part “A” of FIG. 2 , FIG. 5 shows a state during normal operation, and FIG. 6 shows a state during abnormal operation.

First, referring to FIG. 5 during normal operation, the secondary battery according to the present embodiment may include a passage part 310 , a block 500 , and a spring member 600 formed in the battery case 300 . A recess 320 having a structure recessed from the inner surface of the battery case 300 is formed in the bottom 330 of the battery case 300, and a block 500 and a spring member 600 are formed in this recess 320. can be installed. In addition, one side of the passage part 310 may be connected to the discharge hole 311 opened to the outside of the battery case 300 , and the other side of the passage part 310 may be connected to the inflow hole 312 . The inflow hul 312 is formed in the indentation part 320 , and the inflow hole 312 may be blocked by the block 500 during normal operation. Up to this point, the configuration of FIGS. 3 and 4 may be similar. Due to the above configuration, the secondary battery according to the present embodiment may be sealed without releasing gas during normal operation. However, unlike the configuration of FIGS. 3 and 4 , the inlet hole 312 may be formed closer to the electrode assembly 200 , and a passage or the like may not be formed in the block 500 .

Next, referring to FIG. 6 during abnormal operation, in the secondary battery according to the present embodiment, the internal pressure of the battery case 300 may be abnormally increased due to an internal short circuit due to a high temperature environment or an impact. Due to the increase in internal pressure, the spring member 600 is compressed and the block 500 moves, so that the inlet hole 312 formed in the indentation part 320 may be exposed inside the battery case 300 . Accordingly, during abnormal operation, the gas inside may be discharged to the outside through the passage part 310 . The safety of the secondary battery 100 can be increased by forming a passage structure in which opening and closing is automatically controlled according to the internal pressure of the battery case 300 .

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: electrode assembly
300: battery case
310: passage
311: discharge hole
312: inlet hole
500: block

Claims (12)

electrode assembly;
a battery case accommodating the electrode assembly and having a passage portion for discharging gas; and
It is formed in the battery case and includes a block for controlling the opening and closing of the passage,
One side of the passage portion is connected to the discharge hole opened to the outside of the battery case, the other side of the passage portion is connected to the inlet hole,
A secondary battery in which the inlet hole is blocked by the block or connected to the inside of the battery case according to the internal pressure of the battery case, so that gas discharge through the passage is controlled. In claim 1,
The secondary battery further comprising a spring member positioned on a surface of the block facing the electrode assembly and opposite to the surface. In claim 2,
A secondary battery in which the block moves according to the internal pressure of the battery case and the elastic force of the spring member to control gas discharge through the passage. In claim 1,
In normal operation, the inlet hole is blocked in the block,
When the internal pressure of the battery case rises, the block moves and the passage part connects with the inside of the battery case through the inlet hole, so that the gas inside the battery case is discharged to the outside. In claim 1,
A secondary battery in which a connection passage is formed in the block, one side of the connection passage is connected to a first connection hole opened into the battery case, and the other side of the connection passage is connected to a second connection hole. In claim 5,
During normal operation, the second connection hole is displaced from the inlet hole,
When the internal pressure of the battery case rises, the block moves to connect the second connection hole and the inlet hole to each other. In claim 5,
The opening direction of the inlet hole and the opening direction of the discharge hole are perpendicular to each other,
A secondary battery in which an opening direction of the first connection hole and an opening direction of the second connection hole are perpendicular to each other. In claim 1,
The block is a secondary battery mounted in a recessed portion of the structure recessed from the inner surface of the battery case. In claim 8,
The inlet hole is formed in the indentation part. In claim 9,
In normal operation, the inlet hole is blocked by the block,
When the internal pressure of the battery case rises, the block moves to expose the inlet hole to the inside of the battery case. In claim 1,
The block and the passage portion are formed on a bottom portion of the battery case. A device comprising the secondary battery according to claim 1 .

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