KR101305461B1 - Secondary battery - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery, and to a secondary battery capable of improving the sealing property of a battery and improving safety.

In the secondary battery of the present invention, the secondary battery including an electrode assembly, a can opening is formed, an insulating gasket inserted into the opening of the can and a cap assembly coupled to the opening of the can to seal the can, The insulating gasket includes a first region in which the cap assembly is seated, a second region positioned between the side of the can and the cap assembly, and a third region formed to cover an edge of an upper end of the cap assembly. The third region is thicker than the second region.

Therefore, the sealing property of a secondary battery can be improved and a vent can operate normally according to internal pressure, and the safety of a secondary battery can be improved.

Insulation Gasket, Sealed, Cap Assembly, Cap Up, Secondary Battery

Description

Secondary battery

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery, and to a secondary battery capable of improving the sealing property of a battery and improving safety.

Currently, with the spread of portable electronic devices such as portable telephones, notebook computers, camcorders, PDAs, and the like, development of secondary batteries used as power sources of these electronic devices is actively progressing.

Such secondary batteries include various types such as nickel-cadmium batteries, lead storage batteries, nickel-hydrogen batteries, lithium ion secondary batteries, and lithium polymer secondary batteries.

Among these, lithium secondary batteries have been widely used in many fields of recent electric / electronic devices because of their advantages such as small size and large capacity, high operating voltage, and high energy density per unit weight.

The lithium secondary battery may be divided into a can type and a pouch type according to the shape of the outer material accommodating the electrode assembly, and the can type may be further divided into a rectangular shape and a cylindrical shape.

Among them, the cylindrical secondary battery is composed of a can assembly forming an appearance and a cap assembly coupled to an upper opening of the can via an insulating gasket, and containing an electrode assembly and an electrolyte composed of a positive electrode plate, a negative electrode plate, and a separator inside the can. Is done.

The cap assembly is coupled to the top opening of the can in a stacked form of vents, current breakers, PTCs, and cap ups that serve as electrode terminals.

When the internal pressure of the secondary battery becomes higher than a certain level by the gas generated from the electrode assembly, the cap assembly is deformed to break the current flow by breaking the current breaker, and discharges the gas generated from the electrode assembly to the outside. Let's go.

With the cap assembly engaged, a crimping operation is performed to bend the upper end of the insulating gasket into the inside and the bottom of the can together with the opening wall of the can for sealing the secondary battery.

In the prior art as described above, the crimping operation is performed at the upper end of the insulating gasket and the can to help seal the secondary battery, but the crimping operation is performed to insulate the cap assembly from the bending point of the insulating gasket. The gasket is spaced apart, there is a problem that a gap is formed.

In addition, as the gas leaks out between the gap between the cap assembly and the insulating gasket, there is a problem in that the normal operation of the vent is not reduced due to the internal pressure being reduced.

That is, when the internal pressure of the battery is higher than a predetermined level, even though the current breaker is broken by the vent and the current should be cut off, the leaking gas causes the vent to be delayed more than the normal operation.

Therefore, when the vent does not operate normally, a problem may occur in safety of the battery such as explosion, fire, overheating, and the like.

The secondary battery of the present invention for solving the conventional problems as described above to accommodate the electrode assembly, the opening is formed, the insulating gasket is inserted into the opening of the can and coupled to the opening of the can to seal the can A secondary battery comprising a cap assembly, wherein the insulating gasket covers a first region in which the cap assembly is seated, a second region located between the side of the can and the cap assembly, and an edge of an upper end of the cap assembly. And a third region to be formed, wherein the third region is thicker than the second region.

The cap assembly of the present invention is characterized by consisting of a cap up, PTC, CID and vents sequentially located below the cap up.

The cap assembly of the present invention is characterized in that it comprises a cap up, PTC, vent, cap down and sub-plate sequentially located below the cap up.

The cap up of the present invention is characterized in that it comprises an extension extending in the inward direction of the can from the outer edge.

The extension part of the present invention is characterized by covering the side portion of the PTC, CID and vents are laminated to the lower portion of the cap up.

The extension of the present invention is characterized in that the same as the laminated side thickness of the PTC, CID and vent.

According to the present invention as described above, by improving the airtightness of the battery, and by allowing the vent to operate normally in accordance with the internal pressure, it is possible to improve the safety of the battery.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The details of the object and technical construction of the present invention and the resulting effects thereof will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

In addition, in the drawings, distances, thicknesses, and the like of layers and regions may be exaggerated for convenience, and like reference numerals denote like elements throughout the specification.

1 is an exploded perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention, FIG. 2A is a cross-sectional view of the secondary battery before crimping of the rechargeable battery of FIG. 1, and FIG. 2B is a crimping of the rechargeable battery of FIG. 2A. 3 is a cross-sectional view showing another shape of the cap assembly according to the first embodiment.

1 to 2B, two electrodes 21 and 23 formed in a rectangular plate shape are stacked and wound in a spiral shape to form a jelly roll type electrode assembly 20.

At this time, since the separators 25 are positioned one by one between these electrodes and below or above the two electrodes, the separators 25 are interposed between the two electrodes to be wound to prevent a short circuit between the two electrodes.

Each of the electrode plates 21 and 23 is formed by coating a positive electrode active material or a negative electrode active material slurry on a current collector plate made of a metal foil or a metal mesh made of aluminum or copper.

The slurry is usually formed by stirring a granular active material, auxiliary conductor, binder, plasticizer, and the like in a state where a solvent is added. The solvent is removed in the subsequent electrode formation process.

In the direction in which the electrode plate is wound, a portion of the current collector is formed with an uncoated portion in which a slurry is not applied. On the uncoated portion, electrode tabs 27 and 29 are provided one by one on the electrode plate, and the electrode tabs 27 and 29 are formed so that one is drawn upward in the opening direction of the can 10 and the other is drawn downward. do.

The can 10 is formed in various shapes such as a cylinder or a square, and is formed by a deep drawing method using an iron material, an aluminum alloy, or the like.

When the can 10 is formed in a cylindrical shape, a cylindrical side surface is formed to form a cylindrical space for accommodating the electrode assembly, and a lower surface of the cylindrical side surface is formed to block a lower space of the cylindrical side surface. The top of is opened to form an opening.

Subsequently, the electrode assembly 20 is inserted into the can through the opening of the can 10.

In this case, before inserting the electrode assembly 20, the lower insulating plate 11 is first covered on the lower surface of the electrode assembly, and the second electrode tab 29 drawn downward from the electrode assembly 20 bypasses the outer side of the lower insulating plate 11. While being bent in parallel with the bottom of the can 10.

At this time, the electrode assembly 20 forms a cylindrical jelly roll, and the center of the jelly roll is empty to form a hollow.

The center of the lower insulating plate 11 also has a hole in the region corresponding to the hollow of the electrode assembly 20. A portion of the bent downwardly drawn second electrode tab 29 crosses the through hole of the lower insulating plate 11.

In the state provided as described above, the electrode is inserted through the hollow of the electrode assembly from the top to weld the portion of the second electrode tab 29 crossing the central through hole to be attached to the bottom surface of the can 10.

Therefore, the can 10 has the same polarity as that of the second electrode tab 29, so that the can itself can serve as one electrode terminal.

In some embodiments, the can 10 may be provided in a state in which the center pin 13 is coupled to the hollow of the electrode assembly.

The center pin 13 resists deformation caused by external force in the lateral direction, and becomes a moving passage of gas when an internal abnormality occurs and gas is generated in the electrode assembly, and the charge and discharge of the electrode assembly and the deformation over time. It also serves to increase the life of the battery.

After welding the second electrode tab 29, the upper insulating plate 15 is positioned above the electrode assembly 20, and the first electrode tab 27 of the electrode assembly 20 is connected to the electrode through the through hole of the upper insulating plate 15. Allow it to be pulled out of the assembly.

When the upper insulating plate 15 has a central hole, welding of the second electrode tab 19 may be performed after the upper insulating plate 15 is installed.

Then, the sidewalls of the can are bent into the can to form the beads 17 in accordance with the upper level of the upper insulating plate in the case where the electrode assembly or the upper insulating plate is provided on the can.

The bead 17 prevents the electrode assembly from easily flowing up and down inside the can even in the event of external impact, thereby increasing the reliability of the electrical connection.

Subsequently, electrolyte injection is made over the electrode assembly, which may be done before the beads are formed. Thereafter, an insulating gasket 30 is inserted into the can 10 opening, and the cap assembly 40 is coupled to seal the can 10.

At this time, the insulating gasket 30 is a material having an insulating elasticity, has a form that completely surrounds the outer circumferential surface of the cap assembly 30, and insulates between the cap assembly 30 and the can 10 having different polarities. (10) serves to seal.

In addition, the insulating gasket 30 is divided into first, second, and third regions 31, 33, and 35, and the first region 31 is positioned below the insulating gasket 30, so that the cap assembly 40 is disposed. Is seated, and the second region 33 is positioned between the side of the can 10 and the cap assembly 40 to insulate the cap assembly 40 and the can 10.

The third region 35 of the insulating gasket 30 is formed thicker than the second region 33 and is formed to cover the edge of the cap up 80 positioned at the top of the cap assembly 40.

The third region 35 may be formed thicker than the second region 33 by forming the third region 35 thicker in the conventional insulation gasket 30 and the second region in the conventional insulation gasket 30. Removing part of the region 33, and the like.

However, if the third region 35 is too thick, it is difficult to perform crimping, and therefore, the thickness of the third region 35 preferably does not exceed 0.8 mm.

In addition, if the second region 33 is too thin, it should be formed to have a thickness of 0.5 mm or more because it is difficult to perform a short prevention and sealing function between the can 10 and the cap assembly 40.

No problem occurs when the second region 33 and the third region 35 are crimped, and in order to ensure the sealing property, the third region 35 is 1/6 to 1 / of the thickness of the second region 33. 4 thicker is preferable, and preferably 1/5 thicker.

Therefore, the thickness of the second region is preferably formed to be maintained between 0.5 mm and 0.64 mm, which is 4/5 of 0.8 mm, which is the upper limit of the third region.

Further, the thickness of the third region is preferably formed so as to be maintained between 0.6 mm and 0.8 mm, which is 1/5 thicker than 0.50 mm, which is the lower limit of the second region.

Conventionally, since the second region 33 and the third region 35 of the insulating gasket 30 have the same thickness, when the third region 35 is crimped, the crimped insulating gasket 30 A gap occurred in the upper corner.

However, when the third region 35 is formed to be thicker than the second region 33 to cover the edge of the top of the cap assembly 40 as in the present embodiment, the edges that are crimped even though the crimping is performed. The gap can be prevented from occurring.

In addition, the cap assembly 40 may be more firmly coupled to the insulating gasket 30.

The cap assembly 40 may be first installed in the insulating gasket 30 in the form of a combination of the components, or the components may be stacked in the gasket 30 in turn.

The cap assembly 40 is a vent 50 that is electrically connected to the first electrode tab 27, and a current interrupter that is broken by the action of the vent 50 to block a current path (CID: Current Interrupt Device 60). , PTC (Positive Temperature Coefficient, 70), the cap-up 80 to serve as an electrode terminal.

In the cap assembly 40 according to an embodiment of the present invention, a cap up 80 is positioned on a positive temperature coefficient 70 (PTC), and a current interrupter (CID) is disposed below the positive temperature coefficient 70 (PTC). 60 is positioned, and is arranged in a stacked structure in the order that the vent 50 is located below the current breaker (60).

That is, the structure is stacked from the bottom in order of a vent, a current interrupter (CID: 60), a positive temperature coefficient (PTC) 70, and a cap up 80.

The vent 50 breaks a current interrupter (CID: Current Interrupt Device) 60 when the internal pressure is higher than a predetermined level due to the gas generated from the electrode assembly, and blocks the flow of current. To be discharged.

Then, a crimping operation is performed to seal the can by applying pressure inward and downward to an opening wall of the cylindrical can 10 closed by the cap assembly 40 installed inside the insulating gasket 30.

3, which shows another shape of the cap assembly according to the first embodiment of the present invention, the cap up 80 'located at the top of the cap assembly 40' can 10 from the outer edge. An extension portion 81 extending in the inward direction is formed.

The extension portion 81 of the cap up 80 'covers the side portions of the vent 50, the CID 60, and the PTC 70 stacked below the cap up 80', and thus the extension portion 81 ) Is preferably formed to be equal to the stacked side thicknesses of the vent 50, the CID 60, and the PTC 70.

Therefore, since the extension part 81 of the cap up 80 'covers the side parts of the stacked vent 50, the CID 60, and the PTC 70, it is possible to prevent the release of gas leaking through the side parts. The sealing property of a battery can be improved.

4A is a cross-sectional view showing a structure before crimping of a secondary battery according to a second embodiment of the present invention, and FIG. 4B is a cross-sectional view showing another shape of the cap assembly according to the second embodiment.

Referring to FIG. 4A, after the electrode assembly 120 is accommodated in the can 110, an insulating gasket 130 is inserted into an opening of the can 110, and the cap assembly 140 is coupled to the can. Formed by sealing 110.

The components 110 to 130 of the secondary battery illustrated in FIG. 4A have the same configuration as those of the components 10 to 30 of the secondary batteries illustrated in FIGS. 1 and 2B, and play the same role, and thus a detailed description thereof will be omitted. Let's do it.

The cap assembly 140 according to the second embodiment of the present invention includes a PTC 142 located on a lower surface of the cap up 141, and includes a protrusion 143a which is convex downward on the lower surface of the PTC 142. Vents 143 are stacked and formed in the order in which they are located.

However, the PTC 142 may not be positioned, and the vent 143 may be formed on the lower surface of the cap up 141.

In addition, under the vent 143, a hollow cap down 144 is positioned with the insulating material 145 interposed therebetween, and the vent 143 and the cap down 144 are spaced apart from each other by the insulating material 145. .

In addition, the sub plate 146 is positioned below the cap down 144 to cross the hollow formed in the cap down 144, and the sub plate 146 has a protrusion formed in the vent 143 exposed through the hollow ( 143a).

In addition, the electrode tab 127 upwardly drawn out of the electrode assembly 120 may be connected to one surface of the cap down 144 or may be connected to one surface of the sub plate 146.

In this case, the bottom surface of the protrusion 143a of the vent 143 may be configured such that when the battery internal pressure increases, the protrusion direction of the protrusion is increased or reversed so that the electrical connection with the sub plate 146 is broken.

Therefore, the electrical connection is made by the electrode tab 127, the cap down 144, the sub plate 146, the vent 143, the PTC 142, and the cap up 141 which are upwardly drawn from the electrode assembly 120. .

In this case, the subplate 146 and the cap down 144 may be electrically connected by laser welding, and the protrusion 143a and the subplate 146 of the vent 143 may be electrically connected by ultrasonic welding or the like.

After the cap assembly 140 is coupled to the opening of the can 110, a crimping operation is performed to seal the can 110 by applying pressure inward and downward to the opening wall of the can 110.

Referring to FIG. 4B showing another shape of the cap assembly according to the second embodiment of the present invention, the cap up 141 ′ located at the top of the cap assembly 140 ′ is the inner side of the can 110 from the outer edge. Extension portion 141'a extending in the direction is formed.

The extension 141'a of the cap up 141 'covers the side portions of the vent 143 and the PTC 142 stacked below the cap up 141', and thus the extension 141'a. The height of is preferably formed to be equal to the laminated side thickness of the vent 143 and the PTC (142).

Therefore, since the extension part 141 ′ a of the cap up 141 ′ covers the side surfaces of the vent 143 and the PTC 142 stacked thereon, it is possible to prevent the release of gas leaking through the side parts, and to seal the battery. Can improve.

In this embodiment, the PTC 142 is provided below the cap up, but the PTC 142 may not be provided.

When the PTC 142 is not provided, the extension 141 ′ a covers the side portion of the vent 143, and the height of the extension 141 ′ a is formed to be equal to the side thickness of the vent 143.

The present invention shows a preferred embodiment as described above, but is not limited to the above-described embodiment, various changes by those skilled in the art to which the present invention pertains without departing from the present invention And modifications will be possible.

1 is an exploded perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention.

FIG. 2A illustrates a cross-sectional view of the secondary battery of FIG. 1 before crimping. FIG.

FIG. 2B is a cross-sectional view after crimping of the secondary battery of FIG. 2A.

3 is a cross-sectional view showing another shape of the cap assembly according to the first embodiment.

4A is a cross-sectional view illustrating a structure before crimping of a rechargeable battery according to a second exemplary embodiment of the present invention.

4B is a cross-sectional view showing another shape of the cap assembly according to the second embodiment.

[Description of Major Symbols in Drawing]

10, 110: can 11, 111: lower insulation plate

13, 113: center pin 15, 115: phase insulation plate

17, 117: beads 20, 120: electrode assembly

21, 121: first electrode plate 23, 123: second electrode plate

25, 125: Separator 27, 127: First electrode tab

29, 129: second electrode tab 30, 130: insulating gasket

31 and 131: first region 33 and 133: second region

35, 135: third zone 40, 40'140, 140 ': cap assembly

50, 143: vent 60: current breaker

70, 142: PTC 80, 80 ', 141, 141': Cap up

81: extension of the cap up 144: cap down

145: insulating material 146: sub plate

Claims (15)

A secondary battery comprising an electrode assembly accommodating an electrode assembly, an opening formed therein, an insulating gasket inserted into the opening of the can, and a cap assembly coupled to the opening of the can to seal the can. The insulating gasket includes a first region in which the cap assembly is seated, a second region positioned between the side of the can and the cap assembly, and a third region formed to cover an edge of an upper end of the cap assembly. The third region is thicker than the second region. The method of claim 1, The secondary battery has a thickness of 0.5 to 0.64 mm. The method according to claim 1, The thickness of the third region is a secondary battery, characterized in that 0.6 ~ 0.8mm. The method of claim 1, The cap assembly is a secondary battery, characterized in that consisting of a cap up, PTC, CID and vent sequentially positioned below the cap up. 5. The method of claim 4, And the cap up includes an extension part extending in an inward direction of the can from an outer edge thereof. 6. The method of claim 5, The extension part of the secondary battery, characterized in that for covering the side portion of the PTC, CID and vents are stacked below the cap up. The method of claim 6, The extension part is a secondary battery, characterized in that the same as the laminated side thickness of the PTC, CID and vent. The method of claim 1, The cap assembly may include a cap up, a vent, a cap down, and a sub plate sequentially positioned below the cap up. 9. The method of claim 8, And the cap up includes an extension part extending in an inward direction of the can from an outer edge thereof. The method of claim 9, And the extension part covers a side part of a vent positioned under the cap up. 11. The method of claim 10, The extension part is a secondary battery, characterized in that the same as the side thickness of the vent. The method of claim 1, The cap assembly may include a cap up, a PTC, a vent, a cap down, and a sub plate sequentially positioned below the cap up. 13. The method of claim 12, And the cap up includes an extension part extending in an inward direction of the can from an outer edge thereof. 14. The method of claim 13, The extension part of the secondary battery, characterized in that for covering the side of the PTC and the vent laminated on the lower portion of the cap up. 15. The method of claim 14, The extension part is a secondary battery, characterized in that the same as the laminated side thickness of the PTC and the vent.

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