阅读说明：本技术 二次电池 (Secondary battery ) 是由 金度均 郑湘锡 李炳国 李炳九 金餐培 于 2019-03-07 设计创作，主要内容包括：公开了一种二次电池。本发明具有形成于顶盖和第一垫圈紧密接触的区域中的绝缘层,并且该绝缘层可以包含陶瓷材料和粘合剂,使得在外部导电物体与圆柱形二次电池的正极和负极直接电连接的情况下,该二次电池的电极片能够尽可能快地断开连接。(A secondary battery is disclosed. The present invention has an insulating layer formed in a region where a top cap and a first gasket are in tight contact, and the insulating layer may include a ceramic material and a binder, so that electrode tabs of a cylindrical secondary battery can be disconnected as quickly as possible in the case where an external conductive object is directly electrically connected to positive and negative electrodes of the secondary battery.)

1. A secondary battery comprising:

a battery case that receives the electrode assembly and has a structure in which an upper side is open;

a top cover disposed on an upper portion of the battery case;

the safety exhaust device is arranged below the top cover;

a Current Interrupt Device (CID) filter disposed below the safety vent;

a first gasket disposed on an inner surface of the upper portion of the battery case and closely attached to side portions of the safety vent to isolate the safety vent from the upper portion of the battery case; and

a second gasket disposed between the safety vent and the current interrupt device filter, the second gasket being closely attached to an upper portion of the current interrupt device filter to surround an outer end portion of the current interrupt device filter, and the second gasket being closely attached to a lower portion of the safety vent,

wherein an insulating layer is formed on a region where the top cap and the first gasket are closely attached to each other, and

the insulating layer comprises a ceramic material and a binder.

2. The secondary battery according to claim 1, wherein the binder comprises an organic binder.

3. The secondary battery according to claim 1, wherein the ceramic material comprises alumina or silica.

4. The secondary battery according to claim 1, wherein the content of the binder is 20 to 90 wt% based on the total weight of the insulating layer.

5. The secondary battery according to claim 1, wherein a ratio of a thickness of the insulating layer to a thickness of the top cap ranges from 0.015 to 0.15.

6. The secondary battery according to claim 1, wherein a crimping part having a structure of being entirely or partially S-bent is formed on the upper part of the battery case, and

the first washer is closely attached to an inner surface of the crimping portion.

7. The secondary battery according to claim 1, wherein the insulating layer is formed on a top surface of the top cap in an inner region of the first gasket and on a region between an upper end of the crimping portion and the top cap.

8. The secondary battery according to claim 1, wherein the insulating layer has a thickness of 0.015mm to 0.045 mm.

9. The secondary battery according to claim 1, wherein the top cap has a thickness of 0.3 to 1.0 mm.

Technical Field

The present invention relates to a secondary battery, and more particularly, to a secondary battery having a structure capable of solving a safety problem that may occur due to an external short circuit.

Background

As the demand for electronic devices and the development of technologies have accelerated, the demand for secondary batteries for supplying energy to the electronic devices has also increased. In particular, many studies have been made on lithium ion secondary batteries having higher energy density and discharge voltage than those of existing lithium ion secondary batteries.

The secondary battery may be classified into: a cylindrical or prismatic secondary battery having the following structure, and a pouch-type secondary battery: an electrode assembly including electrodes and separators is received in a cylindrical or square metal case, and a pouch-type secondary battery has the following structure: the electrode assembly is accommodated in a pouch type case containing aluminum. Among them, the cylindrical secondary battery is advantageous in that it has a relatively large capacity and is structurally stable.

However, in the case of a secondary battery including a cylindrical secondary battery, the secondary battery may be exposed to various types of dangers during use. In this case, problems such as ignition or explosion of the secondary battery may occur. In order to prevent the above problems, the secondary battery is generally provided with various members for improving the safety of the secondary battery.

The member for improving the safety of the secondary battery may, for example, include a crimp gasket disposed between a crimp part formed in an upper portion of a battery can constituting a main body of the secondary battery and a top cap or a safety vent to seal an inner space of the secondary battery from the outside, and a Current Interrupt Device (CID) gasket disposed between the safety vent and a CID filter.

When an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, it is necessary to cut off the electrode tabs of the secondary battery as soon as possible. However, according to the related art, when the positive electrode and the negative electrode of the secondary battery are directly electrically connected to each other through an external conductive object, there are the following problems: cutting off the current by breaking the electrode tabs requires a lot of time.

Disclosure of Invention

Technical problem

An object to be solved by the present invention is to rapidly cut off current by cutting off electrode tabs as quickly as possible when an external conductive object is directly electrically connected to a positive electrode and a negative electrode of a cylindrical secondary battery.

Technical scheme

According to an aspect of the present invention for achieving the above object, there is disclosed a secondary battery including: a battery case accommodating the electrode assembly and having a structure in which an upper side is open; a top cap disposed on an upper portion of the battery case; the safety exhaust device is arranged below the top cover; a Current Interrupt Device (CID) filter disposed below the safety vent; a first gasket disposed on an inner surface of an upper portion of the battery case and closely attached to side portions of the safety vent to isolate the safety vent from the upper portion of the battery case; and a second gasket disposed between the safety vent and the CID filter and closely attached to an upper portion of the CID filter to surround an outer end portion of the CID filter, the second gasket closely attached to a lower portion of the safety vent, wherein an insulating layer is formed on a region where the top cap and the first gasket are closely attached to each other.

The insulating layer may comprise a ceramic material and a binder.

The ceramic material may comprise alumina or silica.

The content of the binder may be 20 wt% to 90 wt% based on the total weight of the insulating layer.

The ratio of the thickness of the insulating layer to the thickness of the cap may range from 0.015 to 0.15.

The upper part of the battery case may have a crimping part formed thereon, the crimping part having a structure in which it is bent in an S-shape completely or partially, and the first gasket may be closely attached to an inner surface of the crimping part.

An insulating layer may be formed on the top surface of the top cap in an inner region of the first gasket and on a region between an upper end of the crimping portion and the top cap.

The thickness of the insulating layer may be 0.015mm to 0.045 mm.

The thickness of the top cover may be 0.3mm to 1.0 mm.

Advantageous effects

According to the present invention, when an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, it is possible to disconnect the electrode tabs of the secondary battery as quickly as possible to rapidly cut off the current.

Drawings

Fig. 1 is a cross-sectional view illustrating an upper structure of a secondary battery according to a first example of the present invention.

Fig. 2 is a cross-sectional view illustrating an upper structure of a secondary battery according to a second example of the present invention.

Fig. 3 is a cross-sectional view illustrating the structure of a first gasket of a secondary battery according to the present invention.

Detailed Description

Hereinafter, the structure of the secondary battery according to the present invention will be described with reference to the accompanying drawings.

Secondary battery

Fig. 1 is a cross-sectional view illustrating an upper structure of a secondary battery according to a first example of the present invention, and fig. 2 is a cross-sectional view illustrating an upper structure of a secondary battery according to a second example of the present invention.

As illustrated in fig. 1 and 2, a secondary battery 10 according to the present invention may include a battery case 100 in which an electrode assembly (not shown) is received. The battery case 100 may have a structure in which the upper side is open. The battery case 100 may have a cylindrical shape. That is, the secondary battery according to the present invention may be a cylindrical secondary battery.

As illustrated in fig. 1 and 2, a crimping part 110 having a structure bent in an S-shape may be formed in an upper portion of the battery case 100. Here, the expression "the crimping portion 110 has a structure bent in an S-shape" means: the crimping part 110 has at least one region protruding to the outside of the battery case and at least one region protruding to the inside of the battery case. For example, as illustrated in fig. 1 and 2, the upper portion of the crimp part 110 may protrude toward the outside of the battery case 100, and the lower portion of the crimp part 110 may protrude toward the inside of the battery case 100.

A top cap 200 may be disposed on an upper portion of the battery case 100. The top cap 200 may be a constituent member for sealing the open upper portion of the battery case 100.

A safety vent 300 may be provided under the top cover 200. The safety vent 300 may be a constituent element for venting gas within the secondary battery when the internal pressure of the secondary battery exceeds a predetermined range. To this end, a notch 310 may be formed in the safety vent 300, and the thickness of the notch 310 is less than the thickness of each of the other portions of the safety vent 300. Hereinafter, in this specification, the notch formed in the safety vent 300 will be referred to as a "first notch 310". The first notch 310 of the safety vent 300 may be ruptured to discharge gas within the secondary battery when the internal pressure of the secondary battery exceeds a predetermined range. Therefore, it is possible to prevent explosion due to an increase in the internal pressure of the secondary battery.

As illustrated in fig. 1, the safety vent 300 may be closely attached to the lower portion of the top cover 200. Here, as illustrated in fig. 1, the end of the safety vent 300 may be bent upward and then further bent toward the inside of the battery case such that the end of the safety vent 300 surrounds the outer circumferential portion of the top cap 200. On the other hand, as illustrated in fig. 2, the safety vent 300 may have the following structure: the end of the safety vent 300 is bent upward only once to surround the side surface of the top cap 200.

A Current Interrupt Device (CID) filter 400 may be provided under the safety vent 300. A portion of the area of the safety vent 300 and a portion of the area of the CID filter 400 may be closely attached or adhered to each other. For example, as illustrated in fig. 1 and 2, the central portion of the safety vent 300 and the central portion of the CID filter 400 may be closely attached or adhered to each other. The safety vent 300 and the CID filter 400 may be spaced apart from each other except for a region where the safety vent 300 and the CID filter are closely attached to each other or adhere to each other.

The CID filter 400 may be a component configured to cut off the current of the secondary battery in an emergency. To this end, a notch 410 may be formed in the CID filter 400, the notch 410 having a thickness smaller than that of each of the other portions of the CID filter 400. Hereinafter, in this specification, the notch formed in the CID filter 400 will be referred to as "second notch 410". When the internal pressure of the secondary battery exceeds a predetermined range, the CID filter 400 may be broken to cut off the current of the secondary battery. In particular, when the second notch 410 is formed, the CID filter 400 may be broken at the second notch 410. Therefore, it is possible to prevent explosion due to an increase in the internal pressure of the secondary battery.

As described above, the top cap and the safety vent may be provided in the upper portion of the battery case. However, the sealability of the internal space of the battery case may deteriorate as in the past. When the sealability deteriorates, the electrolyte within the secondary battery may leak to the outside, and external foreign substances may be introduced into the secondary battery.

Therefore, in order to improve the sealability of the inner space of the battery case, a gasket 500 may be additionally provided on the upper portion of the battery case 100. The gasket 500 may be disposed on the inner surface of the upper part of the battery case. When the crimping part 110 is formed in the upper part of the battery case 100, the gasket 500 may be closely attached to the inner surface of the crimping part 110. As described above, when the safety vent 300 has a structure bent upward and then bent again toward the inside of the battery case, the gasket 500 may be disposed between the crimping portion 110 and the safety vent, and the gasket 500 may be closely attached to the outer portion of the safety vent. Hereinafter, the gasket 500 disposed on the upper portion of the battery case 100 will be referred to as a "first gasket". The first gasket 500 may be provided to further improve the sealability of the inner space of the battery case.

As described above, the part of the area of the vent safety device 300 and the part of the area of the CID filter 400 may be closely attached or adhered to each other, and the other areas of the vent safety device 300 and the CID filter 400 may be spaced apart from each other. Further, a gasket 600 may be provided between the safety vent 300 and the CID filter 400 such that regions where the safety vent 300 and the CID filter 400 are spaced apart from each other are maintained to be spaced apart from each other. Hereinafter, the gasket 600 provided on the safety vent 300 and the CID filter 400 will be referred to as a "second gasket". A second gasket 600 may be provided to maintain a region where the safety vent 300 and the CID filter 400 are spaced apart from each other in a spaced-apart state.

With continued reference to fig. 1 and 2, in the secondary battery according to the present invention, an insulating layer 700 may be formed on a region where the top cap 200 and the first gasket 500 are closely attached to each other. More preferably, the insulating layer 700 may be adhered to an area on the top surface of the top cap 200 where the top cap 200 and the first gasket 500 are closely attached to each other (see a dotted line in fig. 2). For example, the insulating layer 700 may be formed on the top surface of the top cover 200 in a spray injection (spray injection) manner. Alternatively, the insulating layer 700 may be formed in a coating manner in which a material for forming the insulating layer is applied and pressed to the top surface of the top cap 200, or in a manner in which a material for forming the insulating layer is injected by a nozzle to reach the top surface of the top cap 200 through the nozzle.

The insulating layer 700 may include a ceramic material and a binder (binder). The ceramic material may comprise alumina or silica.

When the positive electrode and the negative electrode of the secondary battery are electrically connected to each other through an external conductive object, heat is generated in the secondary battery while an excessive current flows. In this case, it is preferable to cut off the current flowing through the secondary battery by disconnecting the electrode tabs of the secondary battery for safety.

Here, when an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, it is necessary to cut off the electrode tabs of the secondary battery as soon as possible. However, according to the related art, when the positive electrode and the negative electrode of the secondary battery are directly electrically connected to each other through an external conductive object, there are the following problems: cutting off the current by breaking the electrode tabs requires a lot of time.

The insulating layer according to the present invention may be a component part for solving the problem of taking a lot of time to break the electrode tabs. That is, as a result of experiments performed by the inventors of the present invention, in the case where a separate insulating layer including a ceramic material and a binder is formed on the top surface of the top cap under certain conditions, when an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, it is possible to significantly reduce the time taken to cut off the current by breaking the electrode tabs.

Since the insulating layer 700 of the present invention includes a ceramic material and a binder, an insulating layer having a larger thickness can be formed than when an insulating layer is otherwise formed using a ceramic material.

For example, evaporation may be used as a method of applying the ceramic material to the top cover. However, when the ceramic material is applied to the top cap in an evaporated manner to form the insulating layer, the thickness of the insulating layer may be limited. That is, when the ceramic material is applied to the top cap in an evaporated manner to form the insulating layer, if the thickness of the insulating layer is increased, the insulating layer may be delaminated due to deterioration of adhesion between the ceramic materials. Therefore, the thickness of the insulating layer may be limited. Here, when the thickness of the insulating layer is reduced, heat generated in the secondary battery, particularly, heat generated in the secondary battery in which the electrode tabs are electrically connected to the CID filter, may be easily dissipated. As described above, when heat generated in the upper portion of the secondary battery is dissipated, it may take a considerable time to cut off the current by cutting the electrode tabs since the temperature of the electrode tabs does not rapidly increase.

However, as described above, since the insulating layer according to the present invention includes not only the ceramic material but also the adhesive, the adhesive force between the ceramic materials can be improved by the adhesive. Therefore, even if an insulating layer having a thick thickness is formed on the top cap, the shape of the insulating layer can be maintained to prevent heat generated in the upper portion of the secondary battery from being dissipated to the outside. Therefore, according to the present invention, when an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, the electrode tabs can be quickly disconnected.

When an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, the overall temperature of the secondary battery may be sharply increased if the electrode tabs are not rapidly disconnected. This may cause explosion or ignition of the secondary battery.

However, according to the present invention, when the insulating layer is formed on the top cap such that the electrode tabs are rapidly disconnected, the current of the secondary battery may be cut off to prevent the temperature of the secondary battery from sharply increasing. That is, according to the present invention, a local temperature increase may be caused in a space where the electrode tabs are formed, to rapidly disconnect the electrode tabs and prevent a rapid increase in the temperature of the secondary battery.

The binder of the insulating layer according to the present invention may include an organic binder. As described above, the insulating layer may be formed by coating in a spray manner. When the binder includes an organic binder, since the material forming the insulating layer is kept in a liquid phase in the coating step by the spray method, the coating by the spray method can be smoothly performed.

Further, the content of the binder contained in the insulating layer according to the present invention may be 20 wt% (weight percentage) to 90 wt%, preferably 30 wt% to 70 wt%, more preferably 40 wt% to 50 wt%, based on the total weight of the insulating layer. When the content of the binder is less than 20 wt% based on the total weight of the insulating layer, the bonding between the ceramic materials may not be smoothly performed. On the other hand, when the content of the binder exceeds 90 wt% based on the total weight of the insulating layer, heat generated in the upper portion of the secondary battery may be dissipated to the outside because the amount of the ceramic material is too small. Therefore, the electrode tabs may not be quickly disconnected.

As illustrated in fig. 1, an insulating layer 700 may be formed between the end of the upper part of the crimping part 110 (i.e., the part of the crimping part bent from the upper part of the crimping part toward the inside of the battery case) in the inner region I (see fig. 3) of the first gasket 500 and the top cap 200. Therefore, even if the first gasket 500 is melted, an effect of preventing the battery case 100 and the safety vent 300 from directly contacting each other may be accomplished.

When the insulating layer 700 is formed on the top surface of the top cap 200, the ratio of the thickness of the insulating layer 700 to the thickness of the top cap 200 may range from 0.015 to 0.15. When the ratio of the thickness of the insulating layer 700 to the thickness of the top cap 200 is less than 0.015, since the thickness of the insulating layer is excessively small, heat generated in the upper portion of the secondary battery may be smoothly dissipated to the outside. Therefore, when an external conductive object is directly electrically connected to the positive and negative electrodes of the cylindrical secondary battery, the electrode tabs may not be rapidly disconnected. On the other hand, the ratio of the thickness of the insulating layer 700 to the thickness of the top cap 200 exceeds 0.15, and since the thickness of the insulating layer is excessively large, assemblability of the secondary battery, particularly, the top cap, may be deteriorated, and the secondary battery may be deformed. More preferably, the ratio of the thickness of the insulating layer 700 to the thickness of the top cover 200 may range from 0.021 to 0.064.

In particular, the thickness of the insulating layer 700 may be 0.015mm to 0.045 mm. Further, the top cover 200 may have a thickness of 0.3mm to 1.0 mm.