One]This application claims the benefit of priority based on Korean Patent Application No. 2019-0077738 dated June 28, 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 positive electrode tab fixing member, specifically, a cylindrical secondary battery including a fixing member for fixing the positive electrode tab by omitting the current blocking member from the cap assembly, directly coupling the positive electrode tab to the venting member, and fixing the positive electrode tab It relates to secondary batteries.
background
[3]
A lithium secondary battery is a cylindrical secondary battery or a prismatic secondary battery in which the electrode assembly is embedded in a cylindrical or prismatic metal can depending on the shape of the battery case, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. are classified Among them, the cylindrical secondary battery has an advantage in that it has a relatively large capacity and is structurally stable.
[4]
A cylindrical secondary battery is sealed by placing a cap assembly on the top of an open cylindrical case and interposing a gasket between the cylindrical case and the cap assembly. 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 , the cylindrical secondary battery 100 has an electrode assembly 110 housed inside a cylindrical can 120 , and a cap assembly 130 is positioned on the upper part of the cylindrical secondary battery 100 by means of a crimping gasket 133 ( 100) is sealed.
[6]
The cap assembly 130 surrounds the outer periphery of the top cap 131 and is in contact with the venting member 132 positioned under the top cap and the central portion of the venting member 132 and positioned below the venting member 123. It includes a current blocking member (135). A lower gasket 134 for preventing contact between the venting member 132 and the current blocking member 135 at a portion other than the central portion is positioned on the outer periphery of the current blocking member 135 .
[7]
The positive electrode tab 111 of the electrode assembly 110 is attached to the lower surface of the current blocking member 135 so that the cap assembly 130 serves as a positive terminal.
[8]
As described above, the cap assembly of the cylindrical secondary battery is composed of a top cap, a venting member, a crimping gasket, a current blocking member, and a lower gasket. There is a problem in that the pressure at which the secondary battery is short-circuited is reduced due to the deformation of the current blocking member. .
[9]
In addition, when the overall height of the cap assembly is reduced while maintaining the components of the cap assembly, the deformation space of the venting member is insufficient and the bar is gently deformed, so there is a problem in that it is difficult to specify the time point at which the short circuit occurs, and the gas discharge passage is becoming narrower, acting as an obstacle to gas emission.
[10]
In this regard, in Patent Document 1, the positive electrode tab and the safety vent of the electrode assembly are welded, and when the internal pressure increases due to gas generation, the welding portion of the safety vent and the positive electrode tab is broken to cause a short circuit, and the positive electrode tab is fixed by a gasket It relates to a cap assembly having a structure.
[11]
In Patent Document 1, the structure is simplified by fixing the positive electrode tab to the safety vent, but it must be attached to cross the center of the gasket so that the positive electrode tab is fixed by the gasket, and a deformed gasket is used.
[12]
Patent Document 2 relates to a secondary battery electrically connecting an electrode assembly and a cap assembly, and an electrode tab having a notch is attached to a lower portion of a safety vent, and has a structure in which the notch is cut when a current greater than or equal to a reference current flows.
[13]
Patent Document 3 relates to a secondary battery assembly including a metal grid having a high electrical conductivity mesh-shaped position on an upper side of an electrode assembly, a positive electrode grid in contact with a positive electrode, and a conductive positive electrode current collector plate supporting the positive electrode grid, the electrode The contact resistance may be reduced by increasing the contact point between the current collector and the current collector.
[14]
However, Patent Document 2 and Patent Document 3 can provide a battery cell with improved safety, but do not suggest a method capable of increasing the capacity of the battery cell even when the structure is changed.
[15]
As such, there is a high need for a cylindrical secondary battery having a structure in which a short circuit can occur stably while improving the capacity of the battery by reducing the overall height of the cap assembly.
[16]
(Prior art literature)
[17]
(Patent Document 1) Republic of Korea Patent Publication No. 2018-0005455 (2018.01.16)
[18]
(Patent Document 2) Republic of Korea Patent Publication No. 2014-0082270 (2014.07.02)
[19]
(Patent Document 3) Korean Patent Publication No. 2000-0026860 (May 15, 2000)
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[20]
The present invention is to solve the above problems, and while the capacity of the battery can be increased by simplifying the components of the cap assembly, the venting member is easily separated from the positive electrode tab when the internal pressure is increased by the gas generated inside the secondary battery. An object of the present invention is to provide a cylindrical secondary battery having a stable structure in which gas can be discharged.
means of solving the problem
[21]
A cylindrical secondary battery according to the present invention for achieving this object has an electrode assembly wound with a separator interposed between a positive electrode sheet and a negative electrode sheet, a cylindrical can for accommodating the electrode assembly, and an open top of the cylindrical can and a cap assembly to be mounted, wherein the cap assembly has a protruding structure and is positioned on an upper portion, a venting member formed in a downward concave shape while surrounding an outer periphery of the top cap and positioned under the top cap, and the cylindrical shape It is composed of a gasket for sealing the can, the positive electrode tab of the electrode assembly is directly coupled to the lower surface of the venting member, and may have a structure including an insulating fixing member for fixing the position of the positive electrode tab.
[22]
The positive electrode tab includes a positive electrode tab body and a coupling part bent at one end of the positive electrode tab body and coupled to a lower surface of the venting member, and the fixing member is interposed between the positive electrode tab body and the coupling part.
[23]
The fixing member may be adhered to the coupling part on a surface facing the coupling part.
[24]
A coupling force between the coupling part and the fixing member may be greater than a coupling force between the coupling part and the venting member.
[25]
The fixing member may be located under the gasket.
[26]
The fixing member may form an engagement coupling with the gasket.
[27]
The fixing member may be formed in a sectoral shape or a rod shape in plan view.
[28]
The fixing member may have a structure integrally coupled to an upper insulating plate positioned between the electrode assembly and the cap assembly.
[29]
The fixing member may have a structure in which the fixing member extends upward from the outer periphery of the upper insulating plate and is bent toward the center to be disposed parallel to the upper insulating plate.
[30]
The present invention provides a method for manufacturing the cylindrical secondary battery according to an embodiment, wherein a separator is interposed between a positive electrode sheet and a negative electrode sheet to accommodate the wound electrode assembly in a cylindrical can, the electrode assembly Positioning an upper insulating plate on top of the, forming the beading part, coupling the positive electrode tab of the electrode assembly to the lower surface of the venting member constituting the cap assembly, coupling the fixing member to the gasket constituting the cap assembly and coupling and crimping the cap assembly to the cylindrical can.
[31]
The coupling of the fixing member to the gasket may include coupling the coupling portion of the positive electrode tab to the fixing member.
[32]
The present invention also provides a method for manufacturing a cylindrical secondary battery according to another embodiment, wherein a separator is interposed between a positive electrode sheet and a negative electrode sheet to accommodate the wound electrode assembly in a cylindrical can, the electrode Positioning the upper insulating plate on the upper part of the assembly, forming the beading part, coupling the positive electrode tab of the electrode assembly to the lower surface of the venting member constituting the cap assembly, and the fixing member integrally coupled to the upper insulating plate. securing the positive electrode tab, and coupling and crimping the cap assembly to the cylindrical can.
[33]
The fixing of the positive electrode tab may include bending the positive electrode tab through the lower surface of the fixing member and attaching the positive electrode tab to the upper surface of the fixing member.
Brief description of the drawing
[34]
1 is a vertical cross-sectional view of a conventional general cylindrical secondary battery.
[35]
2 is a vertical cross-sectional view of a cylindrical secondary battery according to an exemplary embodiment.
[36]
3 is an enlarged upper view of FIGS. 1 and 2 .
[37]
4 shows a part of a manufacturing process of a cylindrical secondary battery.
[38]
5 shows a state in which the cylindrical secondary battery fixing member of FIG. 4 is coupled.
[39]
6 is a perspective view of a fixing member according to an exemplary embodiment.
[40]
7 is a perspective view of an upper insulating plate to which a fixing member is coupled according to an exemplary embodiment.
Modes for carrying out the invention
[41]
Hereinafter, embodiments in which those of ordinary skill in the art to which the present invention pertains 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.
[42]
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.
[43]
The present invention will be described along with detailed examples according to the drawings.
[44]
2 is a vertical cross-sectional view of a cylindrical secondary battery according to an exemplary embodiment.
[45]
Referring to FIG. 2 , the cylindrical secondary battery 200 has an electrode assembly 210 accommodated in a cylindrical can 220 , a cap assembly 230 is positioned on the upper portion, and a cylindrical secondary battery 200 is formed by a gasket 233 ( 200) is sealed.
[46]
The cap assembly 230 includes a top cap 231 having a structure in which a center protrudes upward, a venting member 232 positioned under the top cap 231, a cylindrical shape that surrounds the outer periphery of the top cap 231 and is concave downward. It is composed of a gasket 233 that seals the secondary battery while in close contact with the can.
[47]
That is, the cap assembly 230 according to the present invention does not include a current blocking member and a gasket added to the outer periphery of the current blocking member in the cap assembly applied to the conventional cylindrical secondary battery.
[48]
Accordingly, in the cylindrical secondary battery 200 according to the present invention, the positive electrode tab 211 is directly coupled to the lower surface of the venting member 232 .
[49]
However, when the venting member is deformed into an inverted shape due to an increase in the internal pressure of the cylindrical secondary battery, a short circuit must be made by separating from the positive electrode tab, and a fixing member 240 for fixing the position of the positive electrode tab 211 is added.
[50]
Specifically, the lower end of the positive electrode tab is attached to the electrode assembly, and the upper end is coupled to the lower surface of the venting member, and the positive electrode tab is a positive electrode tab body 211a and a coupling portion 211b coupled to the lower surface of the venting member. can be composed of
[51]
The coupling portion 211b is a portion extending by bending the upper end of the positive electrode tab body 211a, and the coupling portion 211b and the positive electrode tab body 211a are positioned to face each other, and the coupling portion 211b and the positive electrode tab body The fixing member 240 is positioned between the 211a so that the positive electrode tab does not move when the venting member 232 is separated from the positive electrode tab.
[52]
Separation of the positive electrode tab body 211a may be prevented by the fixing member 240, but in order to prevent the coupling portion 211b coupled to the venting member 232 from moving upward together with the venting member 232, The fixing member 240 and the coupling portion 211b may be adhered to each other on the facing surfaces.
[53]
That is, the upper surface of the coupling part 211b is coupled to the venting member 232 , and the lower surface of the coupling part 211b is coupled to the fixing member 240 . However, when the venting member 232 is deformed and separated from the coupling part 211b, the coupling between the coupling part 211b and the fixing member 240 must be maintained, and the coupling part 211b and the fixing member 240 are maintained. It is preferable that the coupling force to be coupled is greater than the coupling force between the coupling part 211b and the venting member 232 .
[54]
As described above, as the members constituting the conventional cap assembly are omitted, the overall height of the cap assembly is reduced. When comparing the capacities between battery cells having the same length of the cylindrical secondary battery, the cylindrical secondary battery according to the present invention is Since a wide electrode assembly accommodating space can be secured, a high-capacity secondary battery can be provided.
[55]
In this regard, FIG. 3 is an enlarged upper view of FIGS. 1 and 2 .
[56]
Referring to FIG. 3 , the upper portions of the cylindrical secondary battery 100 of FIG. 1 and the cylindrical secondary battery 200 of FIG. 2 are shown side by side, so that the components of the cap assembly and the overall height of the cap assembly can be compared and venting You can check the change in the size of the deformation space of the member.
[57]
Specifically, the cylindrical secondary battery 200 according to the present invention has a structure in which the lower gasket 134 and the current blocking member 135 are omitted from the conventional cylindrical secondary battery 100 .
[58]
In addition, the distance between the top cap 231 and the venting member 232 in the cylindrical secondary battery 200 according to the present invention is greater than the distance between the top cap 131 and the venting member 132 in the conventional cylindrical secondary battery 100 . increases
[59]
Conventionally, as the overall height of the cap assembly is reduced in order to increase the capacity of the battery cell, the distance between the top cap and the venting member is designed to be short. Accordingly, when the internal pressure of the battery cell is increased, even when a short circuit is required due to a sudden deformation of the venting member, a gentle deformation has to be made, and there is a problem in that it is difficult to specify a time point at which the short circuit occurs.
[60]
The present invention can solve the above problems by designing the gap between the top cap and the venting member to increase as shown in FIG. 3 .
[61]
In addition, the overall height of the cap assembly in the cylindrical secondary battery 200 according to the present invention is reduced compared to the conventional cylindrical secondary battery 100 , and thus, the purpose of manufacturing a high capacity secondary battery can be achieved.
[62]
The manufacturing method of the cylindrical secondary battery 200 according to the present invention includes the steps of accommodating an electrode assembly having a wound structure in a cylindrical can with a separator interposed between a positive electrode sheet and a negative electrode sheet, and placing an upper insulating plate on the top of the electrode assembly forming the beading part, coupling the positive electrode tab of the electrode assembly to the lower surface of the venting member constituting the cap assembly, coupling the fixing member to the gasket constituting the cap assembly, and the cap assembly bonding to and crimping the cylindrical can.
[63]
In addition, coupling the fixing member to the gasket may include coupling the coupling portion of the positive electrode tab to the fixing member.
[64]
In this regard, FIG. 4 shows a part of a manufacturing process of a cylindrical secondary battery, and FIG. 5 shows a state in which the cylindrical secondary battery fixing member of FIG. 4 is coupled.
[65]
4 and 5 , the electrode assembly 210 is accommodated in the cylindrical can 220 , the upper insulating plate 250 is positioned on the upper part of the electrode assembly, and the beading part is on the upper part of the upper insulating plate 250 . 260 is formed.
[66]
The positive electrode tab 211 attached to the electrode assembly 210 is attached to the lower surface of the venting member 232 in a state in which the cap assembly 230 is assembled. One side of the positive electrode tab 211 is coupled to the venting member 232 , and the other side of the positive electrode tab 211 is coupled to the fixing member 240 , and the cap assembly 230 includes the positive electrode tab 211 and the fixing member 240 . In a state in which the member 240 is coupled, it undergoes a process of coupling and crimping to the upper portion of the cylindrical can 220 .
[67]
The fixing member 240 is located under the gasket 233 , and one end of the fixing member 240 overlapping the gasket 233 may form an engagement coupling with the gasket 233 .
[68]
In one specific example, the fixing member 240 may be formed in a planar fan shape or a bar shape.
[69]
In this regard, FIG. 6 shows a perspective view of a fixing member according to an exemplary embodiment.
[70]
Referring to FIG. 6 , the fixing member 241 is formed in a planar bar shape and includes a rectangular base portion 241a for fixing the positive electrode tab and an engagement portion 241b engaged with the gasket. When the fixing member 241 having a small size is used as described above, it is possible to minimize an increase in the weight of the cylindrical secondary battery due to the addition of the fixing member.
[71]
On the other hand, the fixing member 242 may have a sectoral shape on a plane, for example, it is made in a semi-circular shape, and a semi-circular base part 242a for fixing the positive electrode tab and an engagement part 242b for engagement with the gasket and the gasket. ) is included. In the case of using a fixing member including a wide base, such as the fixing member 242 , there is little limitation in setting the position of the fixing member according to the extended position of the positive electrode tab, and stable fixing is possible even when a plurality of positive electrode tabs are included There is this.
[72]
Additionally, a form in which a fixing member is integrally added to the conventional battery cell component may be further proposed, for example, the fixing member is integrally coupled to the upper insulating plate positioned between the electrode assembly and the cap assembly structure may be. Specifically, the fixing member may extend upward from the outer periphery of the upper insulating plate and then be bent toward the center to be disposed parallel to the upper insulating plate.
[73]
In this regard, FIG. 7 is a perspective view illustrating an upper insulating plate to which a fixing member is coupled according to an exemplary embodiment.
[74]
Referring to FIG. 7 , a fixing member 243 integrally coupled to the upper insulating plate 251 is added to the outer periphery of the upper surface of the upper insulating plate 251 , and the fixing member 243 is the upper insulating plate 251 . After extending vertically upward as a reference, it is bent at 90 degrees and positioned parallel to the upper insulating plate.
[75]
The upper insulating plate 251 has a plurality of through holes through which the positive electrode tab 211 attached so as to extend upward from the electrode assembly passes through, and the positive electrode tab 211 passing through the through hole is formed with the fixing member 243 and After passing through the overlapping portion of the upper insulating plate 251, it is bent 180 degrees and is coupled to the upper surface of the fixing member 243.
[76]
However, the positive electrode tab 211 may be positioned between the fixing member and the upper insulating plate in a state coupled to the lower surface of the venting member, and the cylindrical secondary battery manufacturing method when the fixing member 243 is used is, the positive electrode sheet and the negative electrode A step of accommodating an electrode assembly having a wound structure in a cylindrical can with a separator interposed between sheets, placing an upper insulating plate on the top of the electrode assembly, forming a beading part, on the lower surface of the venting member constituting the cap assembly The method may include coupling the positive electrode tab of the electrode assembly, fixing the positive electrode tab to a fixing member integrally coupled to the upper insulating plate, and coupling and crimping the cap assembly to the cylindrical can.
[77]
As described above, the present invention includes a fixing member so that the positive electrode tab is completely separated from the venting member to cause a short circuit when the venting member is deformed, and a space in which the venting member can be deformed is secured more widely so that a stable short circuit can be made. In addition, by reducing the overall height of the cap assembly, it is possible to provide a high-capacity secondary battery.
[78]
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.
[79]
(Explanation of symbols)
[80]
100, 200: cylindrical secondary battery
[81]
110, 210: electrode assembly
[82]
111, 211: positive tab
[83]
120, 220: cylindrical cans
[84]
130, 230: cap assembly
[85]
131, 231: top cap
[86]
132, 232: venting member
[87]
133: crimping gasket
[88]
134: lower gasket
[89]
135: current blocking member
[90]
211a: positive electrode tab body
[91]
211b: coupling part
[92]
233: gasket
[93]
240, 241, 242, 243: fixing member
[94]
241a, 242a: base part
[95]
241b, 242b: engaging portion
[96]
250, 251: upper insulation plate
[97]
260: beading unit
Industrial Applicability
[98]
As described above, the cylindrical secondary battery according to the present invention relates to a cap assembly in which a current blocking member and a gasket added to the outer periphery of the current blocking member are omitted. It is possible to provide a secondary battery with an increased capacity by securing a wider space occupied by the .
[99]
In addition, the positive electrode tab attached to the venting member can be stably fixed by using the fixing member, and the venting member can be separated from the fixed positive electrode tab when the shape of the venting member is changed due to an increase in internal pressure of the secondary battery. flow may be blocked.

WE CLAIMS

an electrode assembly having a wound structure with a separator interposed between the positive electrode sheet and the negative electrode sheet; a cylindrical can for accommodating the electrode assembly; and a cap assembly mounted on the open top of the cylindrical can. The cap assembly includes a top cap positioned at an upper portion in a protruding structure, a venting member disposed in a downward concave shape while surrounding the outer periphery of the top cap and positioned below the top cap, and sealing the cylindrical can A cylindrical secondary battery comprising a gasket for, the positive electrode tab of the electrode assembly is directly coupled to the lower surface of the venting member, and an insulating fixing member for fixing the position of the positive electrode tab.
[Claim 2]
The positive electrode tab of claim 1, wherein the positive electrode tab includes a positive electrode tab body and a coupling part bent at one end of the positive electrode tab body and coupled to a lower surface of the venting member, and the fixing member is disposed between the positive electrode tab body and the coupling part. Cylindrical secondary battery interposed in.
[Claim 3]
The cylindrical secondary battery according to claim 2, wherein the fixing member is adhered to the coupling part on a surface facing the coupling part.
[Claim 4]
The cylindrical secondary battery according to claim 3, wherein the coupling force between the coupling part and the fixing member is greater than the coupling force between the coupling part and the venting member.
[Claim 5]
The cylindrical secondary battery according to claim 1, wherein the fixing member is located under the gasket.
[Claim 6]
The cylindrical secondary battery according to claim 5, wherein the fixing member forms an engagement coupling with the gasket.
[Claim 7]
The cylindrical secondary battery according to claim 1, wherein the fixing member has a sectoral shape or a rod shape on a plane.
[Claim 8]
The cylindrical secondary battery of claim 1, wherein the fixing member is integrally coupled to an upper insulating plate positioned between the electrode assembly and the cap assembly.
[Claim 9]
The cylindrical secondary battery according to claim 8, wherein the fixing member extends upward from the outer periphery of the upper insulating plate and is bent toward the center to be disposed parallel to the upper insulating plate.
[Claim 10]
10. A method of manufacturing a cylindrical secondary battery according to any one of claims 1 to 9, comprising the steps of: accommodating an electrode assembly having a wound structure with a separator interposed between a positive electrode sheet and a negative electrode sheet in a cylindrical can; positioning an upper insulating plate on the electrode assembly; forming a beading part; coupling the positive electrode tab of the electrode assembly to the lower surface of the venting member constituting the cap assembly; coupling a fixing member to a gasket constituting the cap assembly; and coupling and crimping the cap assembly to the cylindrical can. A method of manufacturing a cylindrical secondary battery comprising a.
[Claim 11]
The method of claim 10 , wherein the coupling of the fixing member to the gasket comprises coupling the coupling part of the positive electrode tab to the fixing member.
[Claim 12]
10. A method of manufacturing a cylindrical secondary battery according to any one of claims 1 to 9, comprising the steps of: accommodating an electrode assembly having a wound structure with a separator interposed between a positive electrode sheet and a negative electrode sheet in a cylindrical can; positioning an upper insulating plate on the electrode assembly; forming a beading part; coupling the positive electrode tab of the electrode assembly to the lower surface of the venting member constituting the cap assembly; fixing the positive electrode tab to a fixing member integrally coupled to the upper insulating plate; and coupling and crimping the cap assembly to the cylindrical can. A method of manufacturing a cylindrical secondary battery comprising a.
[Claim 13]
The method of claim 12 , wherein the fixing of the positive electrode tab comprises a step of bending the positive electrode tab through a lower surface of the fixing member and attaching the positive electrode tab to the upper surface of the fixing member.