KR20070107922A - Lithium secondary battery - Google Patents

Abstract

The present invention relates to a lithium secondary battery, and more particularly, by forming an insulating portion at the edge of the safety vane or the side of the cap assembly, even if the gasket is ruptured, the safety vane or the cap assembly does not contact the inner circumferential surface of the can to prevent a short. In addition, the present invention relates to a lithium secondary battery capable of preventing the leakage of the electrolyte by allowing the cap assembly and the gasket to adhere more strongly.

Description

Lithium rechargeable battery

1 is a vertical cross-sectional view of a typical cylindrical lithium secondary battery

2 is a vertical cross-sectional view of a lithium secondary battery according to an embodiment of the present invention.

Figure 3a is a perspective view of the safety van of Figure 2

3B is a cross-sectional view taken along the line A-A of FIG. 3A

4 is a vertical cross-sectional view of a lithium secondary battery according to another embodiment of the present invention.

Figure 5a is a perspective view of the cap assembly of Figure 4

5B is a cross-sectional view taken along line B-B in FIG.

<Description of Symbols for Main Parts of Drawings>

200, 300-lithium secondary battery 205, 305-electrode assembly

240, 340-Can 250, 350-Gasket

261, 361-Safety Vents 263, 363-Insulation

272,372-Current blocking means 273, 373-Secondary protective elements

274, 374-CAP 280, 380-CAP Assembly

The present invention relates to a lithium secondary battery, and more particularly, by forming an insulating portion at the edge of the safety vane or the side of the cap assembly, even if the gasket is ruptured, the safety vane or the cap assembly does not contact the inner circumferential surface of the can to prevent a short. In addition, the present invention relates to a lithium secondary battery capable of preventing the leakage of the electrolyte by allowing the cap assembly and the gasket to adhere more strongly.

In general, as the light weight and high functionality of portable wireless devices such as a video camera, a portable telephone, a portable computer, and the like progress, a lot of researches have been conducted on secondary batteries used as driving power. Such secondary batteries include, for example, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are rechargeable, compact, and large-capacity, and are widely used in advanced electronic devices because of their high operating voltage and high energy density per unit weight.

1 is a vertical cross-sectional view of a general cylindrical lithium secondary battery.

Referring to FIG. 1, the cylindrical lithium secondary battery 100 is assembled to an electrode assembly 105, a cylindrical can 140 containing the electrode assembly 105 and an electrolyte, and an upper portion of the cylindrical can 140. A cap assembly 180 is formed to seal the cylindrical can 140 and allow a current generated in the electrode assembly 105 to flow to an external device.

The electrode assembly 105 includes a positive electrode plate 110 coated with a positive electrode active material layer on a surface of a positive electrode current collector, a negative electrode plate 120 coated with a negative electrode active material layer on a surface of a negative electrode current collector, and the positive electrode plate 110 and a negative electrode plate 120. The separator 130, which is positioned between the electrodes and electrically insulates the positive electrode plate 110 and the negative electrode plate 120, is wound and formed in a jelly-roll shape. Although not shown in detail in the drawing, the positive electrode plate 110 includes a positive electrode current collector made of a thin metal plate having excellent conductivity, for example, aluminum (Al) foil, and a positive electrode active material layer coated on both surfaces thereof. have. At both ends of the positive electrode plate 110, a positive electrode current collector region in which a positive electrode active material layer is not formed, that is, a positive electrode non-coating portion is formed. One end of the positive electrode non-coating portion is generally formed of aluminum (Al), and the positive electrode tab 115 protruding a predetermined length to the upper portion of the electrode assembly 105 is bonded. In addition, the negative electrode plate 120 includes a negative electrode current collector made of a conductive metal plate, for example, copper (Cu) or nickel (Ni) foil, and a negative electrode active material layer coated on both surfaces thereof. Both ends of the negative electrode plate 120 are provided with a negative electrode current collector region, that is, a negative electrode non-coating portion, in which a negative electrode active material layer is not formed. One end of the negative electrode non-coating portion is generally formed of nickel (Ni), and the negative electrode tab 125 protruding a predetermined length to the lower portion of the electrode assembly 105 is bonded. In addition, the upper and lower portions of the electrode assembly 105 may further include insulating plates 134 and 132 for preventing contact with the cap assembly 180 or the cylindrical can 140, respectively.

The cylindrical can 140 may have a cylindrical side plate 141 having a predetermined diameter and a bottom plate sealing the lower portion of the cylindrical side plate 141 to form a predetermined space in which the cylindrical electrode assembly 105 may be accommodated. 142 is formed, and an upper portion of the cylindrical side plate 141 is opened to insert the electrode assembly 105. As the negative electrode tab 125 of the electrode assembly 105 is bonded to the center of the bottom plate 142 of the cylindrical can 140, the cylindrical can 140 itself serves as a negative electrode. In addition, the cylindrical can 140 is generally formed of aluminum (Al), iron (Fe) or an alloy thereof. In addition, the cylindrical can 140 is formed with a clipping portion 143 bent from the top to the inside to press the upper portion of the cap assembly 180 coupled to the upper opening. In addition, the cylindrical can 140 is beaded inwardly so as to press the lower portion of the cap assembly 180 at a position spaced apart from the creeping part 143 by a distance corresponding to the thickness of the cap assembly. A portion 144 is further formed.

The cap assembly 180 includes a safety vent 161, a current blocking means 172, a secondary protective element 173, and a cap up 174. The safety vent 161 has a plate-like protrusion formed at the center at the bottom thereof, and is positioned below the cap assembly 180, and the protrusion is deformed upward by the pressure generated inside the secondary battery. The positive electrode tab 115 drawn from the positive electrode plate 110 and the negative electrode plate 120 of the electrode assembly 105, for example, the positive electrode plate 110, is welded to a predetermined surface of the lower surface of the safety vent 161. The safety vent 161 and the positive electrode plate 110 of the electrode assembly 105 are electrically connected. Here, the other electrode plate, for example, the cathode, of the positive electrode plate 110 and the negative electrode plate 120 is electrically connected to the can 140 by a tab or direct contact method (not shown). The safety vent 161 may be deformed or ruptured when the pressure rises in the can 140 to damage the current blocking means 172.

In general, in a cylindrical lithium secondary battery, a cap assembly including a safety vent, a current interrupting device (CID), a secondary protective device, and a cap up is electrically connected to a positive electrode tab to serve as a positive electrode. Meanwhile, the can is electrically connected to the negative electrode tab to serve as a negative electrode. The cap assembly, including the safety van, rests on the bead of the can and a gasket is inserted to insulate the cap assembly from the can. These gaskets are made of an insulating material. When the battery is subjected to external shock such as a drop, or is used for a power tool, when subjected to a large vibration, or carelessness during the assembly process, the gasket may be damaged or ruptured. In particular, the contact surface with the safety van and the contact surface with the cap-up make the gasket almost vertically folded and more prone to rupture. When the gasket is damaged or ruptured, there is a problem that an internal short may occur due to contact between the cap assembly and the can.

The present invention has been made to solve the above problems, in particular, by forming an insulating portion on the edge of the safety vanes or the side of the cap assembly, even if the gasket is ruptured so that the safety van or cap assembly does not contact the inner peripheral surface of the can short In addition to preventing, it is an object of the present invention to provide a lithium secondary battery that can be in close contact with the cap assembly and the gasket more tightly to prevent the leakage of the electrolyte.

In order to solve the above problems, a lithium secondary battery of one aspect of the present invention includes an electrode assembly, a cap assembly including a can and a safety van for accommodating the electrode assembly, and sealing an upper opening of the can. In the lithium secondary battery made of, characterized in that the insulating portion made of an insulating material formed on the edge portion of the safety vent.

In addition, the insulating part may be made of an elastic material. In addition, the insulation portion may be formed on the bottom and side surfaces of the safety vent. In addition, the insulation portion may be made of a rubber material.

In addition, the insulation may be formed by coating or tubing.

In addition, the lithium secondary battery according to another aspect of the present invention comprises an electrode assembly, a can containing the electrode assembly and a cap assembly for sealing the top opening of the can, in the side of the cap assembly Characterized in that the insulating portion made of an insulating material is formed.

In addition, the insulation portion may be further formed on the upper edge portion and the lower edge portion of the cap assembly. In addition, the insulating part may be made of an elastic material. In addition, the insulation portion may be made of a rubber material.

In addition, the insulation may be formed by coating or tubing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, a cylindrical lithium secondary battery has been described as an example, but the present invention can be applied to a modified form such as an elliptic cylinder.

First, a lithium secondary battery according to an embodiment of the present invention will be described.

2 is a vertical cross-sectional view of a rechargeable lithium battery according to one embodiment of the present invention. 3A is a perspective view of the safety van of FIG. 2, and FIG. 3B is a sectional view taken along line A-A of FIG. 3A.

2, the lithium secondary battery 200 according to an exemplary embodiment of the present invention includes an electrode assembly 205, a can 240, and a cap assembly 280. In this case, the cap assembly 205 includes a safety vent 261, and an insulating portion 263 is formed in the safety vent 261. In addition, the lithium secondary battery 200 may be formed in a cylindrical shape.

The electrode assembly 205 is formed to include a positive electrode plate 210, a negative electrode plate 220, and a separator 230. In addition, the electrode assembly 205 may include a positive electrode tab 215 and a negative electrode tab 225. In addition, the electrode assembly 205 may further include an upper insulating plate 234 and a lower insulating plate 232.

The positive electrode plate 210 includes a positive electrode current collector, a positive electrode active material layer, and a positive electrode non-coating portion. The positive electrode current collector is formed of a conductive metal material to collect electrons from the positive electrode active material layer and move them to an external circuit. The cathode active material layer is prepared by mixing a cathode active material, a conductive material and a binder, and is formed by coating a predetermined thickness on the cathode current collector. The positive electrode non-coating portion is a portion in which a positive electrode active material layer is not formed in the positive electrode current collector. The positive electrode tab 215 is welded to one side of the positive electrode non-coating portion.

The negative electrode plate 220 includes a negative electrode current collector, a negative electrode active material layer, and a negative electrode non-coating portion. The negative electrode current collector is formed of a conductive metal material to collect electrons from the negative electrode active material layer and move them to an external circuit. The negative electrode active material layer is prepared by mixing a negative electrode active material, a conductive material and a binder, and is formed by coating a predetermined thickness on the negative electrode current collector. The negative electrode non-coating portion is a portion in which a negative electrode active material layer is not formed in the negative electrode current collector, and the negative electrode tab 225 is welded to one side of the negative electrode non-coating portion.

The positive electrode tab 215 and the negative electrode tab 225 are respectively welded to the positive and negative electrode portions to serve to electrically connect the electrode assembly 205 and other parts of the battery. The positive electrode tab 215 and the negative electrode tab 225 may be welded by resistance welding, and a lamination tape (not shown) may be attached to the welding portion to prevent short and heat generation. Here, the welding method of the positive electrode tab 215 and the negative electrode tab 225 is not limited.

The separator 230 may be interposed between the positive electrode plate 210 and the negative electrode plate 220 and extend to surround the outer circumferential surface of the electrode assembly 205. The separator 230 is formed of a porous membrane polymer material to prevent short circuit between the positive electrode plate 210 and the negative electrode plate 220 and to allow lithium ions to pass therethrough.

The can 240 is formed in a cylindrical shape including a side plate 241 and a bottom plate 242. In addition, the side plate 241 has an outer circumferential surface and an inner circumferential surface that are substantially concentric with each other, and the lower plate 242 has a front and a rear surface which are substantially parallel to each other. An upper end of the can 240 is opened to form an upper opening, and an electrode assembly 205 is inserted through the upper opening, and an electrolyte is injected. A lower insulating plate 232 may be inserted between the bottom plate 242 and the electrode assembly 205 of the can 240 to insulate the can 240 and the electrode assembly 205. The upper portion of the can 240 prevents the electrode assembly 205 from flowing in the can 240 after the electrode assembly 205 is inserted, and the beading portion 244 is mounted to seat the cap assembly 280. After the insertion of the cap assembly 280, the creeping unit 243 may be formed to seal the battery. An upper insulating plate 234 may be inserted between the upper end of the electrode assembly 205 and the cap assembly 280 to insulate between the electrode assembly 205 and the cap assembly 280. The can 240 is formed of a light and ductile aluminum or its alloy material, it is not limited to the material of the can 240. The can 240 is preferably manufactured by a deep drawing method, and the method of manufacturing the can 240 is not limited thereto.

The cap assembly 280 may include a safety vent 261, a current blocking means 272, a secondary protective element 273, and a cap up 274.

The safety vent 261 is positioned at the bottom of the cap assembly 280, and is formed to be electrically connected to the current blocking means 272 at an upper portion thereof. 3A and 3B, the safety vent 261 includes a body portion 262, a deformation portion 265, and an insulation portion 263. The body portion 262 may be formed in a substantially disk shape. A protrusion may be formed at a position spaced apart from the edge of the body portion 262 by a predetermined distance so as to be in close contact with the gasket 250. The protrusion may have a vertical cross-sectional shape having a substantially V-shape, and may not be formed depending on the design of the battery. The deformable portion 265 is formed at approximately the center of the safety vent 261. The deformable portion 265 may be formed to a thinner thickness than the body portion 262. The deformable portion 265 may be formed such that an end thereof is connected to the body portion 262 and protrudes into a smooth curved surface in a downward direction of the safety vent 261. The deformable portion 265 is deformed convexly upward when the pressure inside the battery reaches a predetermined value or more, thereby breaking the current blocking means 272 to cut off the current. The insulation part 263 may be formed at an edge portion of the safety vent 261. In more detail, the insulation portion 263 may be formed to surround the outermost end of the body portion 262. The insulating part 263 may be formed to surround the top, bottom, and side surfaces of the edge of the safety vane 261, but the side of the edge of the safety vane 261 in order to facilitate electrical contact with the current blocking means 272. It is preferable to be formed in the lower surface. The insulating part 263 is made of an insulating material and may be formed by a coating method or a tubing method. However, the method of forming the insulating portion 263 is not limited thereto. In addition, the insulating portion 263 may be made of an elastic material, and in particular, may be made of a rubber material. For example, the insulation portion 263 may be coated with a general resin material or an elastic resin material, or may be coated or tubed with a rubber material. Here, the tubing means that the safety vent 261 may be inserted into the insulating portion 263 which is formed in a substantially ring shape made of rubber or the like. The insulating part 263 is formed to be in close contact with the gasket 250 on the outside while surrounding a portion of the side surface and the bottom surface of the edge portion of the safety vent 261. When the gasket 250 is damaged or destroyed due to external force such as external shock or vibration, the insulating part 263 prevents contact between the safety vent 261 and the can 240 so that a short does not occur.

The current blocking means 272 is formed above the safety vent 261. The current blocking means 272 is formed to include an outer ring and a cross bar having an outer diameter approximately equal to that of the safety vent 261. The crossbar is formed to cross the inside of the outer ring, and a conductive pattern is formed on the surface by a metal thin film. A via hole for electrically connecting the lower conductive pattern and the upper conductive pattern to each other is formed at approximately the center of the crossbar. Since the conductive pattern of the current interruption means 272 is broken, no current flows through the battery, and as a result, the battery is not ignited or exploded.

The secondary protection element 273 may be formed of a material of which resistance is maximized by temperature rise. Therefore, when the temperature inside the battery rises, the secondary protection device 273 improves safety by preventing the current from flowing rapidly due to a rapid increase in resistance. The upper portion of the secondary protection element 273 is further positioned a conductive cap up 274 for providing a positive voltage or a negative voltage to the outside. In addition, the cap assembly 280 is further provided with a gasket 250 to insulate the cap assembly 280 serving as an anode and the can 240 serving as a cathode.

Next, a lithium secondary battery according to another embodiment of the present invention will be described.

4 is a vertical sectional view of a lithium secondary battery according to another embodiment of the present invention. FIG. 5A is a perspective view of the cap assembly of FIG. 4, and FIG. 5B is a B-B cross-sectional view of FIG. 4. The embodiment of FIG. 4 is similar to the embodiment of FIG. 2 except that the insulating portion 363 is formed on portions and sides of the top and bottom surfaces of the cap assembly 280, and thus, the difference will be described.

According to another exemplary embodiment of the present invention, referring to FIG. 4, the lithium secondary battery 300 includes an electrode assembly 305, a can 340, and a cap assembly 380. The electrode assembly 305 is formed to include a positive electrode plate 310, a negative electrode plate 320, and a separator 330. In addition, the electrode assembly 305 may further include a positive electrode tab 315, a negative electrode tab 325, an upper insulating plate 334, and a lower insulating plate 332. The can 340 includes a side plate 341, a bottom plate 342, a beading portion 344, and a creeping portion 343.

5A and 5B, the cap assembly 380 may include a safety vent 361, a current blocking means 372, a secondary protective element 373, and a cap up 374. In addition, the cap assembly 380 is insulated from the can 340 by a gasket 350.

As shown in FIG. 5B, the cap assembly 380 may have an insulating portion 363 formed at an upper edge, a lower edge, and a side surface thereof. Although not shown, the insulating portion may be formed only on the side of the cap assembly, of course. In addition, although not shown, the insulating portion may be formed only on a portion and the side surface of the safety vent, a portion and the side surface of the cap up.

The insulating part 363 is made of an insulating material and may be formed by a coating method or a tubing method. In addition, the insulating part 363 may be made of an elastic material, and in particular, may be made of a rubber material. In addition, the insulating portion 363 may have a vertical cross-sectional shape having a substantially C shape. The insulating part 363 may be formed to cover the top edge of the cap up 374, the side of the cap assembly 380, and the bottom edge of the safety vent 361. The insulating part 363 is formed to be in close contact with the gasket 350 to the outside. When the gasket 350 is damaged or destroyed due to external force such as external shock or vibration, the insulating part 363 prevents contact between the cap assembly 380 and the can 340 so that a short does not occur.

Next, the operation of the lithium secondary battery according to the embodiment of the present invention will be described. Hereinafter, for convenience, a lithium secondary battery according to the embodiment of FIG. 4 will be described as an example.

Referring to FIG. 4, a lithium secondary battery 300 according to an exemplary embodiment of the present invention includes a safety vent 361, a current blocking means 372, a secondary protective element 373, and a cap up 374. The cap assembly 280 is formed.

The lithium secondary battery 300 may be subjected to a severe impact due to a drop or the like. In addition, when the lithium secondary battery 300 is used for an electric tool or the like, intense vibration may be transmitted. The cap assembly 380 and the can 340 have opposite polarities, and are insulated from each other by the gasket 350. However, the upper edge or the lower edge of the cap assembly 380 protrudes relatively sharply and may damage or destroy the gasket 350 when such an impact is applied. Insulating parts 363 are formed at the top, bottom, and side surfaces of the cap assembly 380, so that the cap assembly 380 and the can 340 may be directly exposed even if a part of the gasket 350 is torn due to the impact. Contact can be prevented. As a result, the short caused by the contact between the cap assembly 380 and the can 340 can be prevented.

In addition, when the lithium secondary battery is located in the reverse direction or subjected to severe vibration, the electrolyte may leak into the minute gap between the cap assembly and the gasket. When the electrolyte solution is repeatedly subjected to external shocks such as capillary phenomenon, cohesion, etc., there is a risk that the electrolyte will leak out of the battery through the minute gap. In the lithium secondary battery 300, an insulating part 363, such as an elastic material, is closely formed between the cap assembly 380 and the gasket 350 to prevent the electrolyte from leaking.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

According to the lithium secondary battery according to the present invention, even if an external shock, vibration, or the like is applied, the safety van or the cap assembly is prevented from directly contacting the can, thereby preventing the occurrence of a short inside the battery.

In addition, according to the present invention, the insulating portion made of an elastic material or the like adheres closely between the cap assembly and the gasket, thereby preventing the electrolyte from leaking out of the battery.

Claims (10)

An electrode assembly, A can containing the electrode assembly; In the lithium secondary battery comprising a cap assembly for providing a safety vent and sealing the top opening of the can, Lithium secondary battery, characterized in that the insulating portion is formed of an insulating material on the edge portion of the safety vent. The method of claim 1, The insulating part is a lithium secondary battery, characterized in that made of an elastic material. The method of claim 1, The insulating part is a lithium secondary battery, characterized in that formed on the bottom and side of the safety vent. The method of claim 1, The insulating part is a lithium secondary battery, characterized in that made of a rubber material. The method of claim 1, The insulating part is a lithium secondary battery, characterized in that formed by coating or tubing (tubing) method. An electrode assembly, A can housing the electrode assembly; In the lithium secondary battery comprising a cap assembly for sealing the top opening of the can, Lithium secondary battery, characterized in that the insulating portion made of an insulating material is formed on the side of the cap assembly. The method of claim 6, The insulating part is a lithium secondary battery, characterized in that further formed on the upper edge and the lower edge of the cap assembly. The method of claim 6, The insulating part is a lithium secondary battery, characterized in that made of an elastic material. The method of claim 6, The insulating part is a lithium secondary battery, characterized in that made of a rubber material. The method of claim 6, The insulating part is a lithium secondary battery, characterized in that formed by coating or tubing.

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