KR20070006248A - Cylinder type secondary battery - Google Patents

Abstract

Provided is a cylindrical secondary battery, which has a gasket surrounding a beading portion to improve sealing characteristics between a can and the gasket and to prevent an electrode assembly from moving when external impact is applied. The cylindrical secondary battery comprises: an electrode assembly(20) formed by winding a positive electrode, a negative electrode and a separator interposed between both electrodes; a can(10) for housing the electrode assembly; a cap assembly coupled to the top of the can; and a gasket(30) inserted between the cap assembly and the top of the can under pressure for maintaining insulation and sealing between the cap assembly and the can. The secondary battery further comprises a beading portion(15) formed at the outer wall of the can in the upper part of the top of the electrode assembly under a pressure acting inwardly thereto, wherein the beading portion is surrounded with the gasket.

Description

Cylindrical Secondary Battery {CYLINDER TYPE SECONDARY BATTERY}

1 is a front sectional view of a cylindrical secondary battery according to an embodiment of the present invention;

Figure 2 is an enlarged cross-sectional view schematically showing a cylindrical secondary battery having a gasket surrounding the beading portion according to an embodiment of the present invention,

3 is an enlarged cross-sectional view schematically showing a cylindrical secondary battery having an auxiliary beading portion supporting a lower end of a gasket according to another embodiment of the present invention;

4 is an enlarged cross-sectional view schematically illustrating a cylindrical secondary battery in which a lower end of the gasket contacts the upper end of the electrode assembly according to another exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: cylindrical can 13a, 13b: upper and lower insulating plates

15: beading unit 17: auxiliary beading unit

20: electrode assembly 30: gasket

80: cap assembly

The present invention relates to a cylindrical secondary battery, and more particularly, to a cylindrical secondary battery having a high sealing property between the can and the gasket by forming a gasket to wrap the bead portion.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in the field of advanced electronic devices such as a cellular phone, a notebook computer, a camcorder, and the like. In particular, lithium secondary batteries have an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as electronic equipment power sources, and are rapidly increasing in terms of high energy density per unit weight.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. Moreover, although lithium secondary batteries are manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. A battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. In the case of a lithium secondary battery, a nonaqueous electrolyte is used even when a liquid electrolyte is used due to the reactivity of lithium and water (H ₂ O). As the non-aqueous electrolyte is used, the lithium ion battery may have a relatively high battery voltage because it is not controlled by the decomposition voltage of water during charging. The liquid electrolyte has a state in which lithium salts are dissociated in an organic solvent. As the solvent in which the lithium salt is dissolved, ethylene carbonate, propylene carbonate or other alkyl group-containing carbonate or similar organic compound is used.

In a lithium secondary battery using a solid electrolyte, there will be no problem of leakage of the electrolyte, but in the case of a lithium ion battery using a liquid electrolyte, preventing leakage of the electrolyte is an important problem as in the case of a general chemical battery. In particular, the problem of leakage prevention becomes more important when considering that a portable telephone, a computer, a personal digital assistant, a camcorder, etc., in which a lithium ion battery is used as a power source, is an expensive precision device.

The cylindrical secondary battery includes an electrode assembly, a cylindrical can, a cap assembly, and a gasket.

Looking at the structure and manufacturing process of the cylindrical secondary battery schematically, the electrode assembly is accommodated in the cylindrical can, a beading portion is formed in the can to prevent flow of the electrode assembly in the can, the electrolyte is injected. An insulating gasket is installed on the inner wall of the can, and a cap assembly is provided to close the opening of the can.

Then, a crimping operation is performed to seal the can by applying pressure to the opening wall of the cylindrical can inwards and downwards with a cap up and the like injected into the gasket. In addition, a tubing operation of applying an exterior material to the outside of the battery is performed, thereby completing the battery.

As with a general chemical battery using a liquid electrolyte, it is necessary to prevent the electrolyte inside the battery from leaking to the outside even in a cylindrical secondary battery in which the electrolyte is injected. To this end, in the related art, a gasket is placed on the beading part, and a cap assembly is placed in the gasket, and then the cap assembly and the can are sealed through the crimping operation.

However, in spite of the above-mentioned efforts, there has been a problem in which a leak of electrolyte is leaked along a path between the gasket and the can, and various efforts to improve the same have been made.

On the other hand, the beading portion is formed on the outer wall of the upper can of the upper portion of the electrode assembly to prevent the flow of the electrode assembly in the can, nevertheless a slight empty space may occur between the beading portion and the top of the electrode assembly.

Accordingly, the electrode assembly may flow up and down when the battery is dropped or vibrated, and the flow may damage the electrode assembly or damage the coupling between the electrode assembly and the electrode tab.

The present invention is to solve the above problems, the object is to increase the sealing between the can and the gasket by forming a gasket to surround the bead. Furthermore, the purpose is to prevent the flow of the electrode assembly by the external impact by reducing or eliminating the empty space between the bead portion and the top of the electrode assembly.

Cylindrical secondary battery of the present invention in order to achieve this object,

An electrode assembly in which two different electrodes and a separator interposed between the two electrodes are stacked and wound; A can in which the electrode assembly is accommodated; A cap assembly assembled to the top of the can; And a gasket that is compressed between the cap assembly and the upper portion of the can to maintain insulation and sealing between the cap assembly and the can.

The beading portion pressed inwardly is formed on an outer wall of the can of the upper upper portion of the electrode assembly, and the gasket is formed to surround the beading portion.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a cylindrical secondary battery according to the present invention.

1 is a front sectional view of a cylindrical secondary battery according to an embodiment of the present invention.

Referring to the drawings, a cylindrical secondary battery includes an electrode assembly 20, a can 10 containing the electrode assembly 20, a cap assembly 80 coupled to the can 10, and a can 10. It comprises a gasket 30 interposed between the top and the cap assembly 80.

The electrode assembly 20 typically forms two different electrodes 25 in a wide plate shape in order to increase capacitance, and thereafter, separators 21 and 23 are insulated from each other and positioned below or above the two electrodes. It is then laminated, rolled up in a circle to form a so-called 'Jelly Roll'. The two electrode plates are formed by coating an active material slurry on a current collector made of metal foil or metal mesh made of aluminum and copper, respectively. 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 electrodeposition process. In the direction in which the electrode plate is wound, there is a non-coated portion at which the slurry is not applied at the start end and the end of the current collector. In the uncoated portion, electrode tabs 27 and 29 are provided one by one in the electrode plate, and the electrode tabs may be formed to be pulled out of the electrode one upward in the direction of the opening of the cylindrical can and the other downward, or both tabs. It may be formed to be drawn upward in the opening direction.

The can 10 has a cylindrical shape as shown, is a container made of a lightweight conductive metal such as aluminum or an aluminum alloy, and is formed by a processing method such as deep drawing. The lower insulating plate 13b and the electrode assembly 20 are sequentially installed in the cylindrical can 10, and the upper insulating plate 13a may be further provided on the electrode assembly 20. At this time, the center pin (not shown) that prevents the release of the jelly roll and serves as a movement passage of the internal gas may be inserted into the empty space in the center of the jelly roll. The electrode tab 29 drawn downward is bent to be parallel to the bottom surface of the jelly roll type electrode assembly 20 and welded to the bottom surface of the cylindrical can 10. At this time, the lower insulating plate 13b is positioned between the bent electrode tab 29 and the lower surface of the electrode assembly 20 such that the lower surface of the electrode assembly 20 is not short-circuited with the bottom surface of the can 10. The upper insulating plate 13a serves to insulate between the jelly roll and the cap assembly 80. If there is a phase insulator plate 13a, the can 10 of the upper part of the electrode assembly 20 is directly along the outer periphery of the can 10 of the upper part of the upper insulator plate 13a. It may be possible to prevent the flow of the electrode assembly 20 by forming the beading portion 15 by pressing inward from the outside along the outer circumference of the).

In addition, the electrolyte can be injected into the cylindrical can. This electrolyte serves to move lithium ions generated by the electrochemical reaction in the electrode 25 during charging and discharging. The electrolyte may be a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high purity organic solvent, or may be a polymer using a polymer electrolyte, and the type of the electrolyte is not limited thereto.

As shown in the cap assembly 80, the vent 40, the current breaker 50, the PTC 60, and the cap up 70 are sequentially positioned from the bottom. Vent 40 is located at the bottom of the cap assembly 80, the center of the event 40 has an electrical connection 42 is projected convex downwards and electrically connected to the electrode tab (27). Above the vent 40, a current interrupter (CID) 50 is provided, which is configured to be broken by the convex deformation of the electrical connection portion 42 of the vent 40 upward. A PTC (Positive Thermal Coefficient) 60 is provided above the current breaker 50, which blocks the flow of current in the battery due to overheating of the battery. Above the PTC, a cap up 70 having an electrode terminal convexly formed to be electrically connected to the outside is provided.

A gasket 30 is positioned between the top of the can 10 and the cap assembly 80 to seal and insulate the can 10 from the cap assembly 80. In detail, it is as follows.

Figure 2 is an enlarged cross-sectional view schematically showing a cylindrical secondary battery having a gasket surrounding the bead portion in accordance with an embodiment of the present invention.

Referring to the drawings, the beading portion 15 pressed inwardly is formed on the outer wall of the can 10 of the upper portion of the electrode assembly 20, and the gasket 30 is formed to surround the beading portion 15. The gasket 30 preferably has a shape complementary to the beading portion 15 at a portion corresponding to the beading portion 15 to be in close contact with the beading portion 15.

In the conventional gasket, since a crimping operation is performed for sealing in a state in which the gasket is simply placed on the bead part, there is a risk that the structure of the gasket contacting the bead part is deformed. On the contrary, according to the present invention, by forming the gasket 30 so as to surround the beading part 15, the sealing property between the can 10 and the gasket 30 can be improved.

Furthermore, an adhesive layer (not shown) may be interposed between the gasket 30 and the can 10. As such an adhesive layer, an adhesive or a double-sided tape may be used. Thereby, the sealing property between the can 10 and the gasket 30 can be further improved, and the leakage of electrolyte solution can be prevented more reliably.

Such a gasket may be made of a material such as PET (Poly-Ethylene-Terephthalate), but may be made of rubber or silicon. In this case, vibration of the electrode assembly 20 due to external shock may be absorbed to increase stability of the battery.

3 is an enlarged cross-sectional view schematically illustrating a cylindrical secondary battery having an auxiliary beading part supporting a lower end of a gasket according to another exemplary embodiment of the present invention.

Referring to the drawings, the beading portion 15 pressed inwardly is formed on the outer wall of the can 10 of the upper portion of the electrode assembly 20, and the gasket 30 is formed to surround the beading portion 15. In addition, an auxiliary beading unit 17 supporting the lower end of the gasket 30 is formed under the beading unit 15.

The auxiliary beading part 17 allows the lower end of the gasket 30 to be in close contact with the can 10, and does not change the structure of the gasket 30 in close contact with the can 10 due to a crimping operation or external impact. Help me avoid

In addition, an adhesive layer (not shown) may be interposed between the gasket 30 and the can 10. Thereby, the sealing property between the can 10 and the gasket 30 can be further improved, and the leakage of electrolyte solution can be prevented more reliably.

4 is an enlarged cross-sectional view schematically illustrating a cylindrical secondary battery in which a lower end of the gasket contacts the upper end of the electrode assembly according to another exemplary embodiment of the present invention.

Referring to the drawings, the beading portion 15 pressed inwardly is formed on the outer wall of the can 10 of the upper portion of the electrode assembly 20, and the gasket 30 is formed to surround the beading portion 15. The lower end of the gasket 30 is in contact with the upper end of the electrode assembly 20.

Accordingly, it is possible to prevent the flow of the electrode assembly 20 due to external impact by eliminating the empty space between the bead 15 and the upper end of the electrode assembly 20.

On the other hand, if the phase insulating plate (not shown) is positioned on the electrode assembly 20, the bottom of the gasket 30 and the phase insulating plate may be made to contact. Accordingly, it is possible to prevent the flow of the electrode assembly 20 due to external impact by eliminating the empty space between the bead 15 and the phase insulating plate.

Such a gasket may be made of a material such as PET (Poly-Ethylene-Terephthalate), but may be made of rubber or silicon. In this case, vibration of the electrode assembly 20 due to external shock may be absorbed to increase stability of the battery.

In the cylindrical secondary battery according to the present invention, by forming a gasket to surround the beading part, the sealing property between the can and the gasket can be increased to reliably prevent leakage of the electrolyte. Further, by reducing or eliminating the empty space between the beading portion and the top of the electrode assembly, it is possible to prevent the flow of the electrode assembly due to external impact, thereby preventing damage to the electrode assembly and bonding damage between the electrode assembly and the electrode tab.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (7)

An electrode assembly in which two different electrodes and a separator interposed between the two electrodes are stacked and wound; A can containing the electrode assembly; A cap assembly assembled to an upper portion of the can; And a gasket that is compressed between the cap assembly and an upper portion of the can to maintain insulation and sealing between the cap assembly and the can. A cylindrical secondary battery, characterized in that the bead is pressed inward on the outer wall of the can on the upper portion of the electrode assembly, the gasket is formed to surround the bead. The method of claim 1, The gasket may have a shape complementary to the beading portion at a portion corresponding to the beading portion to be in close contact with the beading portion. The method of claim 1, Cylindrical secondary battery, characterized in that the auxiliary beading portion for supporting the lower end of the gasket is formed under the beading portion. The method of claim 1, A cylindrical secondary battery, characterized in that the lower end of the gasket is in contact with the upper end of the electrode assembly. The method of claim 1, A phase insulator plate is positioned on the electrode assembly, and a bottom end of the gasket and the phase insulator plate are in contact with each other. The method according to any one of claims 1 to 5, Cylindrical secondary battery, characterized in that the adhesive layer is interposed between the gasket and the can. The method according to any one of claims 1 to 5, The gasket is a cylindrical secondary battery, characterized in that the rubber material or silicon material.

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