[One]This application claims the benefit of priority based on Korean Patent Application No. 2019-0072473 dated June 18, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[2]
The present invention relates to a cylindrical secondary battery including a grooved gasket, and more specifically, to a cylindrical secondary battery including a grooved gasket in which safety at high temperature is improved by modifying the shape of a gasket adjacent to a high temperature portion of a cap assembly. It's about batteries.
background
[3]
Lithium secondary batteries are classified into a cylindrical secondary battery or a prismatic secondary battery in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. Among them, the cylindrical secondary battery has an advantage in that it has a relatively large capacity and is structurally stable.
[4]
In the cylindrical secondary battery, a cap assembly is placed on the top of an open cylindrical case, and a gasket is interposed between the cylindrical case and the cap assembly to be sealed. The gasket also has a function of securing insulation between the cap assembly connected to the positive electrode tab of the electrode assembly and the cylindrical case connected to the negative electrode tab.
[5]
1 shows a vertical cross-sectional view of a typical cylindrical secondary battery. Referring to FIG. 1 , in the cylindrical secondary battery 100 , the jelly-roll type electrode assembly 110 is accommodated inside the cylindrical battery case 120 , and the cap assembly 130 is positioned on the upper portion of the cap assembly 130 . The cylindrical secondary battery 100 is sealed by the gasket 133 .
[6]
The cap assembly 130 surrounds the outer periphery of the top cap 131 and is in contact with the safety vent 132 positioned under the top cap and the center of the safety vent 132 and blocks current positioned under the safety vent 132 . member 134 . A second gasket 135 for preventing the safety vent 132 and the current blocking member 134 from contacting at a portion other than the central portion is positioned on the outer periphery of the current blocking member 134 .
[7]
The positive electrode tab 111 of the jelly-roll type electrode assembly 110 is attached to the lower surface of the current blocking member 134 so that the cap assembly 130 serves as a positive electrode terminal.
[8]
In this regard, a portion of the top cap 131 in which an opening for discharging gas is not formed may be overheated due to heat generated by the positive electrode tab, and there is a possibility that the portion in contact with the heat generating portion of the top cap may be melted in the first gasket. this is high When the first gasket is melted, there may be a problem in sealing the secondary battery or a problem in that the battery case and the tab assembly are in contact with each other to conduct electricity.
[9]
FIG. 2 is a lower perspective view illustrating a positional relationship between the second gasket and the positive electrode tab of FIG. 1 .
[10]
Referring to FIG. 2 , the positive electrode tab 111 extended by being attached to the jelly-roll type electrode assembly is coupled to a current blocking member (omitted), and the end of the positive electrode tab 111 is coupled to the current blocking member stably. When 112 is bent, the end 112 of the positive electrode tab 111 may be coupled to the lower surface of the current blocking member. That is, the positive electrode tab is not coupled to the central portion of the lower surface of the current blocking member, but is coupled to one side in a biased state. In the second gasket 135 , the portion adjacent to the end 112 of the positive electrode tab is a positive electrode, which is the main heating part. It can be melted by the temperature of the tap. In this case, the current blocking member 134 and the safety vent 132 may be energized.
[11]
Accordingly, the first gasket and the second gasket may be manufactured and used with a material having a high melting point, but this causes an increase in manufacturing cost and thus is difficult to apply.
[12]
Patent Document 1 relates to a sealed battery including an internal gasket having convex portions formed on both sides thereof, and it is possible to prevent the PTC element or explosion-proof valve in the sealed internal part from malfunctioning by inhibiting the penetration of electrolyte into the sealed internal part, A technique capable of preventing the gasket from melting due to heat generation of the cap assembly has not been disclosed.
[13]
Patent Document 2 discloses a structure in which a gasket formed with a groove is inserted therebetween for insulation between a cap assembly used as a positive electrode terminal and a can used as a negative terminal, but the structure for preventing melting of the gasket for the current blocking member is can't start
[14]
Patent Document 3 discloses a structure in which a groove is formed in the direction of the battery can in the gasket interposed between the cap assembly and the battery can, and does not correspond to a technique for preventing the gasket from melting by the heated top cap.
[15]
Patent Document 4 relates to a cylindrical battery cell in which a recessed groove into which a gasket is partially introduced by clamping is formed on the inner surface of a clamped portion as an upper portion of a metal can, and a structure for preventing the gasket from being damaged during the clamping process to be.
[16]
As such, a solution for preventing damage to the gasket due to high temperature in a cylindrical secondary battery has not been proposed, and there is a high need for a technology capable of improving sealing and insulating properties by preventing the melting of the gasket in an easy way. the current situation.
[17]
(Prior art literature)
[18]
- (Patent Document 1) Japanese Patent Application Laid-Open No. 1999-283588 (October 15, 1999)
[19]
- (Patent Document 2) Korean Patent Publication No. 2000-0051436 (2000.08.16)
[20]
- (Patent Document 3) Japanese Patent Application Laid-Open No. 2009-135008 (2009.06.18)
[21]
-(Patent Document 4) Korean Patent Publication No. 2018-0036086 (2018.04.09)
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[22]
The present invention is to solve the above problems, by modifying the shape of the first gasket interposed between the top cap and the battery case to minimize the contact portion between the high temperature part of the top cap and the first gasket, and To provide a cylindrical secondary battery including a gasket having a groove portion formed therein so that the high-temperature positive electrode tab can have a structure that maintains a maximum distance from the second gasket by modifying the shape of the second gasket located on the outer periphery The purpose.
means of solving the problem
[23]
A cylindrical secondary battery according to the present invention for achieving this object includes a cylindrical can for accommodating an electrode assembly including a positive electrode, a negative electrode, and a separator, a cap assembly positioned on the cylindrical can, a top cap of the cap assembly, and a venting member A first gasket for sealing the cylindrical can in a state of being added to surround the outer periphery of the can, a current blocking member (CID) located under the cap assembly, and a second gasket located on the outer periphery of the current blocking member The upper end of the first gasket has a structure surrounding the upper surface of the outer periphery of the top cap, and at least a portion of the inner surface of the upper end of the first gasket is formed with a groove portion for preventing contact with the upper surface of the outer periphery of the top cap It may be a structured structure.
[24]
The top cap may include a bridge connecting the protruding central portion and the outer periphery of the top cap, and the groove portion may be formed at an upper end of the first gasket facing the outer periphery of the top cap connected to the bridge.
[25]
A length connecting both ends of the groove portion may be greater than a width of the bridge.
[26]
The groove portion may have a structure in which grooves of a uniform depth are formed as a whole.
[27]
The groove portion may have a structure in which the concave portion and the convex portion are continuously formed.
[28]
The thickness of the convex part may be the same as the thickness of the upper end of the first gasket in which the groove part is not formed.
[29]
A thickness of the convex portion may be smaller than a thickness of an upper end portion of the first gasket in which the groove portion is not formed.
[30]
The upper end of the first gasket may have a porous structure.
[31]
The second gasket includes an upper portion positioned on the upper surface of the outer periphery of the current blocking member to prevent contact between the venting member and the current blocking member, and a side portion located outside the outer periphery of the current blocking member, at least a portion of the upper portion A punch may be formed.
[32]
The punching part may be formed at a position adjacent to the positive electrode tab coupled to the current blocking member.
[33]
The punching part may have a form in which an inner part of an upper portion of the second gasket is removed.
[34]
The punching part may have a structure in which a groove is formed on a lower surface of an upper portion of the second gasket.
[35]
The groove may have a slit shape.
Brief description of the drawing
[36]
1 is a vertical cross-sectional view of a typical cylindrical secondary battery.
[37]
FIG. 2 is a lower perspective view illustrating the positional relationship between the second gasket and the positive electrode tab of FIG. 1 ;
[38]
3 is a perspective view of the cap assembly;
[39]
4 is a first embodiment of a first gasket.
[40]
5 is a second embodiment of the first gasket.
[41]
6 is a first embodiment of a second gasket.
[42]
7 is a second embodiment of a second gasket.
Modes for carrying out the invention
[43]
Hereinafter, embodiments in which those skilled in the art can easily practice the present invention will be described in detail with reference to the accompanying drawings. However, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the gist of the present invention in describing in detail the principle of operation according to the preferred embodiment of the present invention, the detailed description thereof will be omitted.
[44]
In addition, the same reference numerals are used throughout the drawings for parts having similar functions and functions. Throughout the specification, when it is said that a part is connected to another part, it includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of a certain component does not exclude other components unless otherwise stated, but means that other components may be further included.
[45]
The present invention will be described along with detailed examples according to the drawings.
[46]
3 is a perspective view of the cap assembly;
[47]
Referring to FIG. 3 , the cap assembly has a structure in which the first gasket 220 surrounds the outer periphery of the top cap 210 . The top cap 210 includes a protruding central portion 211 , an opening 213 for discharging gas generated inside the cylindrical can, and a bridge 212 connecting the central portion 211 and the outer periphery.
[48]
A positive electrode tab is coupled to the lower surface of the current blocking member positioned at the lower end of the cap assembly, and the positive electrode tab is a passage through which current flows, and is a portion in which heat is particularly severe.
[49]
Accordingly, the temperature of the cap assembly connected to the positive electrode tab increases as a whole. In particular, in the first gasket 220 , the upper end of the first gasket 220 facing the outer periphery of the top cap connected to the bridge 212 of the top cap exhibits the highest temperature distribution.
[50]
Accordingly, the present invention proposes a structure capable of preventing the melting of the first gasket by minimizing the contact between the outer periphery of the top cap and the first gasket, thereby suppressing the high temperature of the bridge from being transmitted to the first gasket.
[51]
In this regard, FIG. 4 is a first embodiment of the first gasket, and FIG. 5 is a second embodiment of the first gasket.
[52]
Referring to FIG. 4 , the first gasket 230 has a structure in which a groove 232 is formed on the inner surface of the upper end 231 .
[53]
Specifically, the groove 232 is formed in the upper end 231 of the first gasket facing the outer periphery of the top cap connected to the bridge of the top cap.
[54]
The thickness of the grooves 232 at the upper end of the first gasket may be uniformly formed, and the same number of grooves 232 as the number of bridges formed in the top cap used may be formed.
[55]
At the upper end of the first gasket, the thickness of the groove portion 232 is thinner than the thickness of the portion where the groove portion is not formed in the first gasket, and a space spaced apart from the upper surface of the top cap is formed in the groove portion 232 of the first gasket. .
[56]
The size of the groove portion 232 is preferably larger than the outer peripheral portion of the top cap connected to the bridge, and the length (a1) connecting both ends of the groove portion 232 in the gasket 230 is that of the bridge 212 of FIG. It may be larger than the width a2.
[57]
Referring to FIG. 5 , the first gasket 240 has a structure in which a groove portion 242 is formed on an inner surface of the first gasket upper end portion 241 .
[58]
Like the first gasket 230 of FIG. 4 , the groove portion 242 of the first gasket 240 is formed on the inner surface of the upper end of the first gasket facing the outer periphery of the top cap connected to the bridge of the top cap. .
[59]
The groove part 242 has a structure in which the concave part 242a and the convex part 242b are continuously formed, and the thickness d2 of the convex part 242b is equal to the thickness d1 of the upper end of the first gasket in which the groove part is not formed. In the case of the same size, the upper surface of the outer periphery of the top cap connected to the bridge and the concave portion 242a of the groove do not come into close contact with the convex portion 242b of the groove.
[60]
As described above, by partially removing the contact point between the high-temperature portion of the cap assembly and the first gasket, it is possible to suppress damage to the first gasket due to transmission of a high temperature to the first gasket.
[61]
Alternatively, when the thickness d2 of the convex portion 242b is smaller than the thickness d1 of the upper end portion of the first gasket in which the groove portion is not formed, the upper surface of the outer periphery of the top cap connected to the bridge and the entire groove portion are spaced apart. Since it is configured to be such that it is possible to minimize transmission of a high temperature to the first gasket.
[62]
Alternatively, the upper ends 231 and 241 of the first gaskets 230 and 240 have a porous structure to minimize transmission of high temperature to the first gasket, and the side portions 233 and 243 of the first gaskets 230 and 240 are It may be of a high density structure for sealing of cylindrical cans.
[63]
In general, a second gasket is located on the outer periphery of the current blocking member positioned under the cap assembly, and the second gasket can maintain insulation between the current blocking member and the safety vent when the current blocking member and the safety vent are separated. functions that exist.
[64]
A positive electrode tab of the electrode assembly is attached to the lower surface of the current blocking member, and the positive electrode tab is attached to a position biased to one side from the center of the current blocking member, and the portion close to the positive electrode tab in the second gasket has the highest temperature distribution looks like
[65]
In this regard, FIG. 6 is a first embodiment of the second gasket, and FIG. 7 is a second embodiment of the second gasket.
[66]
Referring to FIG. 6 , the second gasket 350 includes a second upper gasket 351 positioned on the upper surface of the outer periphery of the current blocking member to prevent contact between the venting member and the current blocking member, and the outer periphery of the current blocking member. It includes a second gasket side portion 352 positioned in the , and at least a portion of the second gasket upper portion 351 is formed with a punching portion 353 .
[67]
6 shows the positive electrode tab 111 extended to be attached to the lower surface of the current blocking member by a dotted line, the second gasket upper portion 351 is adjacent to the positive electrode tab end 112 coupled to the current blocking member. A punching part 353 of the form in which the inner part of the has been removed is formed.
[68]
The punched portion 353 is preferably formed at a size and position to secure a separation distance from the positive electrode tab 111, and the length c1 connecting both ends of the punched portion is greater than the width c2 of the positive electrode tab size is preferred.
[69]
Accordingly, the distance between the positive electrode tab end 112 and the second gasket 350 may be maximized.
[70]
Referring to FIG. 7 , the second gasket 360 includes a second upper gasket 361 positioned on the upper surface of the outer periphery of the current blocking member to prevent contact between the venting member and the current blocking member, and the outer periphery of the current blocking member. It includes a second gasket side portion 362 positioned in the, and at least a portion of the second gasket upper portion 361 is formed with a punching portion 363.
[71]
The punching part 363 has a structure in which a groove is formed on the lower surface of the second gasket upper part 361, and the groove is in the form of a slit. Alternatively, as another embodiment, the punching part may have a structure in which a through hole is formed.
[72]
Therefore, when the safety vent is deformed due to an increase in internal pressure of the cylindrical secondary battery and the safety vent coupled with the current blocking member is separated, the insulation between the safety vent and the current blocking member can be secured, and the high heat of the positive electrode tab causes the second gasket to prevent damage to the second gasket.
[73]
The punched part 363 is also formed on the second gasket adjacent to the end 112 of the positive electrode tab in the same way as the punched part 353 of FIG. 6, and the length connecting both ends of the punched part is greater than the width of the positive electrode tab. Big.
[74]
For reference, in the positive electrode tabs shown in FIGS. 6 and 7, the opposite end of the positive electrode tab end 112 coupled to the current blocking member is positioned to be spaced apart from the bar cap assembly, which is a portion connected to the electrode assembly, as shown in the drawing. Unlike the drawing, it is not positioned adjacent to the second gasket.
[75]
As described above, the present invention provides a cylindrical secondary battery with improved safety at high temperature as well as securing sealing properties and insulation by applying a modified shape of the first gasket and the second gasket.
[76]
Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.
[77]
(Explanation of symbols)
[78]
100: cylindrical secondary battery
[79]
110: jelly-roll type electrode assembly
[80]
111: positive tab
[81]
112: the end of the positive electrode tab
[82]
120: cylindrical battery case
[83]
130: cap assembly
[84]
131, 210: top cap
[85]
132: safety vent
[86]
133, 220, 230, 240: first gasket
[87]
134: current blocking member
[88]
135, 350, 360: the second gasket
[89]
211: central
[90]
212: bridge
[91]
213: opening
[92]
231, 241: upper part of the first gasket
[93]
232, 242: groove
[94]
233, 243: the side of the first gasket
[95]
242a: recess
[96]
242b: convex part
[97]
351, 361: upper portion of the second gasket
[98]
352, 362: second gasket side
[99]
353, 363: punching part
[100]
a1: Length connecting both ends of the groove
[101]
a2: width of bridge
[102]
c1: Length connecting both ends of the punched part
[103]
c2: width of positive tab
[104]
d1: the thickness of the upper portion of the first gasket in which the groove portion is not formed
[105]
d2: thickness of the convex portion
Industrial Applicability
[106]
As described above, in the cylindrical secondary battery according to the present invention, since the groove is formed in the first gasket, the top cap, which is a high temperature portion, and the portion in which the first gasket does not come into close contact are formed. Accordingly, it is possible to minimize the melting of the first gasket due to the heat of the top cap.
[107]
In addition, since the punching part is formed in the second gasket, the distance between the second gasket and the positive electrode tab can be maximally maintained, and melting of the second gasket due to heat generated by the positive electrode tab can be minimized.
[108]
In this way, the high temperature stability can be improved by changing the shape of the first gasket and the second gasket, and an additional process is unnecessary to ensure high temperature safety, so it can be easily applied to the conventional cylindrical secondary battery manufacturing process do.
[109]
In addition, it is possible to reduce the manufacturing cost by not using an expensive heat-resistant material.

WE CLAIMS

a cylindrical can for accommodating an electrode assembly including an anode, a cathode, and a separator; a cap assembly positioned above the cylindrical can; a first gasket sealing the cylindrical can while being added to surround the outer periphery of the top cap and the venting member of the cap assembly; a current blocking member (CID) positioned under the cap assembly; and a second gasket positioned on the outer periphery of the current blocking member. wherein the upper end of the first gasket has a structure surrounding the upper surface of the outer periphery of the top cap, and at least a portion of the inner surface of the upper end of the first gasket has a groove for preventing it from being in close contact with the upper surface of the outer periphery of the top cap Cylindrical secondary battery in which a part is formed.
[Claim 2]
The top cap according to claim 1, wherein the top cap includes a bridge connecting the protruding center and the outer periphery of the top cap, and the groove is formed at an upper end of the first gasket facing the outer periphery of the top cap connected to the bridge. cylindrical secondary battery.
[Claim 3]
The cylindrical secondary battery according to claim 2, wherein a length connecting both ends of the groove portion is greater than a width of the bridge.
[Claim 4]
The cylindrical secondary battery according to claim 1, wherein the groove portion is formed with a groove having a uniform depth as a whole.
[Claim 5]
The cylindrical secondary battery according to claim 1, wherein the groove portion has a structure in which a concave portion and a convex portion are continuously formed.
[Claim 6]
The cylindrical secondary battery according to claim 5, wherein the thickness of the convex portion is the same as the thickness of the upper end portion of the first gasket in which the groove portion is not formed.
[Claim 7]
The cylindrical secondary battery according to claim 5, wherein a thickness of the convex portion is smaller than a thickness of an upper end portion of the first gasket in which the groove portion is not formed.
[Claim 8]
The cylindrical secondary battery of claim 1, wherein the upper end of the first gasket has a porous structure.
[Claim 9]
According to claim 1, wherein the second gasket comprises an upper portion positioned on the upper surface of the outer periphery of the current blocking member to prevent contact between the venting member and the current blocking member, and a side portion located outside the outer periphery of the current blocking member, A cylindrical secondary battery having a punching part formed on at least a portion of the upper part.
[Claim 10]
The cylindrical secondary battery according to claim 9, wherein the punching part is formed adjacent to the positive electrode tab coupled to the current blocking member.
[Claim 11]
The cylindrical secondary battery according to claim 9, wherein the punching part has a shape in which an inner part of an upper portion of the second gasket is removed.
[Claim 12]
The secondary battery according to claim 9, wherein the punching part has a structure in which a groove is formed on a lower surface of an upper portion of the second gasket.
[Claim 13]
The cylindrical secondary battery according to claim 12, wherein the groove has a slit shape.