KR20060112741A - Cylindrical li secondary battery - Google Patents

Abstract

Provided is a cylindrical lithium ion secondary battery which is enhanced in the stability to an external pressure by dispersing the external pressure to many directions and by preventing the deformation of an electrode assembly. The cylindrical lithium ion secondary battery comprise an electrode assembly which comprises a first electrode plate, a second electrode plate and a separator interposed between the first electrode plate and the second electrode plate, is wound in vortex and has a certain space at center of winding; a winding spool member(600) which has a pipe shape having a cut groove(630) along a longitudinal direction, is divided into a main body part and left and right parts by two symmetrical first bent parts and is inserted into the center space of the electrode assembly; a case which has a space for accommodating the electrode assembly; and a cap assembly which is combined with the upper part of the case to seal it. The extended ling of the external side of the main body part forms an imaginary circumference, and the left and right parts are located inside the circumference.

Description

Cylindrical Lithium Secondary Battery

1 is a perspective view for explaining a conventional core member.

Figure 2a is a perspective view for explaining a cylindrical lithium secondary battery according to an embodiment of the present invention.

FIG. 2B is a cross sectional view along line A-A in FIG. 2A;

FIG. 2C is a cross sectional view along line B-B in FIG. 2A; FIG.

3A is a plan view illustrating a plate member for a core member of a cylindrical lithium secondary battery according to an embodiment of the present invention.

Figure 3b is a perspective view for explaining the core member of the cylindrical lithium secondary battery according to an embodiment of the present invention.

3C is a cross sectional view along line C-C in FIG. 3B;

4A is a plan view for illustrating a core member plate of a cylindrical lithium secondary battery according to an embodiment of the present invention.

Figure 4b is a perspective view for explaining the core member of the cylindrical lithium secondary battery according to an embodiment of the present invention.

4C is a cross-sectional view taken along the line D-D in FIG. 4B.

5 is a sequential explanatory diagram for explaining a method for manufacturing a cylindrical lithium secondary battery according to an embodiment of the present invention.

6A to 6D are views for explaining a method of manufacturing a cylindrical lithium secondary battery according to one embodiment of the present invention.

(Explanation of symbols for main parts of drawing)

200; Cylindrical lithium secondary battery 300; Electrode assembly

310; A first electrode plate 315; First electrode tab

320; Second electrode plate 325; Second electrode tab

330; Separators 341, 345; Insulation Plate

400; Cylindrical case 410; Cylindrical surface

420; If 430; Creeping Part

440; Beading unit 500; Cap assembly

510; Safety van 520; Printed circuit board

530; Positive temperature element 540; Electrode cap

550; Gaskets 600, 700; Absenteeism

600 ', 700'; Plate members 610 and 710 for core members; First bend

620, 720; Second bends 630 and 730; Incision groove

640, 740; Third bent portion 800; Winding shaft

The present invention relates to a cylindrical lithium secondary battery, and more particularly to a cylindrical lithium secondary battery with improved battery stability against external pressure.

Recently, compact and lightweight electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. These portable electric / electronic devices have a battery pack that can be operated in a place where no separate power source is provided. The built-in battery pack includes at least one battery therein for outputting a predetermined level of voltage for driving the portable electric / electronic device for a period of time.

In view of economical aspects, the battery pack employs a secondary battery capable of charging and discharging. Representative secondary batteries include lithium secondary batteries such as nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic equipment, and is rapidly increasing in terms of high energy density per unit weight. to be.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte, and 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 addition, the lithium secondary battery is manufactured in various shapes, and typical examples thereof include a cylindrical shape, a square shape, and a pouch type.

In general, the cylindrical lithium secondary battery is positioned between a positive electrode plate coated with a positive electrode active material, a negative electrode plate coated with a negative electrode active material, and between the positive electrode plate and the negative electrode plate to prevent a short and prevent lithium ions (Li-ion). The electrode assembly is formed of a cylindrical body wound around a cylindrical shape, which allows only movement of the electrode, a cylindrical case accommodating the electrode assembly, and an electrolyte solution injected into the cylindrical case to allow lithium ions to move.

This cylindrical lithium secondary battery is manufactured as follows.

First, the positive electrode active material is coated and the positive electrode tab is connected to the positive electrode tab, the negative electrode active material is coated, and the negative electrode tab is connected to the negative electrode plate and the separator is laminated, and then wound in a substantially cylindrical shape to manufacture an electrode assembly.

Then, the substantially cylindrical electrode assembly is accommodated in the cylindrical case to prevent the electrode assembly from being separated, the electrolyte is injected into the cylindrical case, and then sealed to complete the cylindrical lithium secondary battery.

Cylindrical lithium secondary batteries as described above generally generate spaces in the center of the electrode assembly. This space has a problem that can cause loosening and deformation of the electrode assembly.

Meanwhile, in order to solve the problems as described above, a method of inserting the core member 100 as shown in FIG. 1 is introduced into a space at the center of the electrode assembly.

The core member 100 is generally formed by rolling a kind of plate, and has a circular cross-section, and has a shape in which a portion is cut along the length direction.

However, the core member 100 has a problem in that it is easily deformed or easily broken by deformation such as compression by external pressure.

In particular, when the core member 100 is deformed or broken, the separator of the electrode assembly may be destroyed, and the destruction of the separator may cause a short between the positive electrode plate and the negative electrode plate, thereby causing the cylindrical lithium secondary. There is a fatal problem that can cause battery destruction or explosion.

In addition, when the external pressure is applied to the core member 100, its deformation direction is concentrated only at one place. Therefore, the deformation of the core member 100 occurs in a place where the external pressure is concentrated, thereby applying pressure only in one direction to the electrode assembly. Therefore, there is a problem of more seriously causing deformation of the electrode assembly.

An object of the present invention is to solve the above problems of the prior art, the present invention is to provide a cylindrical lithium secondary battery with improved battery stability against external pressure.

Cylindrical lithium secondary battery of the present invention for achieving the above object is provided with a separator interposed between the first electrode plate, the second electrode plate, the first electrode plate and the second electrode plate is wound in a spiral shape, winding center An electrode assembly having a predetermined space formed therein; It is formed in a tubular shape formed with a cutting groove along the longitudinal direction, and divided into a body portion and left and right side ends through two first bent portions symmetrical with respect to the cutting groove, and inserted into a central space of the electrode assembly. Lack of core; A case having a space for accommodating the electrode assembly; And a cap assembly coupled to the top of the case to seal the cap assembly. An extension line of the outer surface of the body portion of the core member forms a virtual circumference, and the left and right side ends are formed in the first bent portion. It is located inside the circumference, and the left and right side ends are bent in a rotational direction opposite to the first bent portion through the second bent portion, respectively.

It is preferable that the portion located on the outside of the left and right side ends with respect to the second bent portion is bent in the rotational direction of the second bent portion through the third bent portion.

It is preferable that the ends of the left and right side end portions are located on an extension line of the outer surface of the body portion.

It is preferable that the angle which the surface which passes each 2nd bending part of the said left and right side end part, and the surface which passes the central axis of the said core member meet is 120 degrees or less.

It is preferable that the said core member consists of a metal material.

It is preferable that the diameter of the upper part and the lower part of the said core member is smaller than the diameter of a center part.

The height of the core member is preferably 90% to 110% of the height of the electrode assembly.

In addition, the cylindrical lithium secondary battery of the present invention is provided with a separator interposed between the first electrode plate, the second electrode plate, the first electrode plate and the second electrode plate is wound in a spiral shape, a predetermined space in the winding center An electrode assembly formed; It is formed in a tubular shape formed with a cutting groove along the longitudinal direction, and divided into a body portion and left and right side ends through two first bent portions symmetrical with respect to the cutting groove, and inserted into a central space of the electrode assembly. Lack of core; A case having a space for accommodating the electrode assembly; And a cap assembly coupled to an upper portion of the case to seal the cap assembly, wherein an extension line of the body portion of the core member forms a virtual circumference, and the left and right side ends are formed by the first bent portion. Located in the interior, the left and right side ends are each bent in the direction of rotation of the first bent portion through the second bent portion.

A portion located outside the left and right side ends with respect to the second bent portion is preferably bent in a rotational direction opposite to the second bent portion via a third bent portion.

It is preferable that the ends of the left and right side end portions contact the inner circumferential surface of the body portion.

It is preferable that the angle which the surface which passes each 2nd bending part of the said left and right side end part, and the surface which passes the central axis of the said core member meet is 120 degrees or less.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Like reference numerals in the drawings denote like elements.

2A is a perspective view illustrating a cylindrical lithium secondary battery according to an embodiment of the present invention, FIG. 2B is a cross-sectional view taken along the line A-A of FIG. 2A, and FIG. 2C is a cross-sectional view taken along the line B-B of FIG. 2A.

As shown in FIGS. 2A to 2C, the cylindrical lithium secondary battery 200 according to the exemplary embodiment of the present invention includes an electrode assembly 300 for generating a voltage difference during charging and discharging, and a housing of the electrode assembly 300. A cylindrical case 400, a cap assembly 500 assembled on the cylindrical case 400 to prevent the electrode assembly 300 from being separated, and a core located in a central space of the electrode assembly 300. It is composed of a structure having a member 600.

The electrode assembly 300 may include any one of a positive electrode active material and a negative electrode active material, for example, a first electrode plate 310 coated with a positive electrode active material, another one of the positive electrode active material and the negative electrode active material, for example, a negative electrode active material. A short of the first electrode plate 310 and the second electrode plate 320 is disposed between the coated second electrode plate 320, the first electrode plate 310, and the second electrode plate 320. ) And a separator 330 capable of only moving lithium ions. In addition, the first electrode plate 310, the second electrode plate 320, and the separator 330 are wound in a spiral shape, and a predetermined space is formed in the winding center, and the cylindrical case 400 is formed. Is housed in. In addition, the first electrode plate 310 is generally made of aluminum (Al) and is bonded to the first electrode tab 315 protruding a predetermined length upward. The second electrode plate 320 is generally made of nickel (Ni) material, but the second electrode tab 325 protruding to a predetermined length is bonded to the second electrode plate 320, but is not limited thereto. In addition, upper and lower insulating plates 341 and 345 are further attached to upper and lower portions of the electrode assembly 300 to avoid direct contact with the cap assembly 500 or the cylindrical case 400, respectively.

The cylindrical case 400 has a cylindrical surface 410 having a predetermined space and a predetermined diameter so that the electrode assembly 300 can be coupled, the cylindrical surface 410 at the lower portion of the cylindrical surface 410 A lower surface 420 is formed to block a lower space of the upper side of the bottom surface. An upper portion of the cylindrical surface 410 is opened to insert the electrode assembly 300. Meanwhile, any one of the first electrode tab 315 and the second electrode tab 325 of the electrode assembly 300, for example, the second electrode tab () in the center of the lower surface 420 of the cylindrical case 400. As the 325 is bonded, the cylindrical case 400 itself serves as the same electrode as the second electrode plate 320, for example, a negative electrode terminal. In addition, the cylindrical case 400 is generally formed of aluminum (Al), iron (Fe) or an alloy thereof. In addition, the cylindrical case 400 is formed with a crimping portion 430 bent to one side to press the cap assembly 500 from the top, and inward to press the cap assembly 500 from the bottom to the upper direction. A recessed beading portion 440 is further formed.

The cap assembly 500 is electrically and mechanically connected to an upper portion of the safety vent 510 and a conductive safety vent 510 in which the first electrode tab 315 is welded and whose shape is reversed when overcharging or overheating. When the safety vent 510 is inverted, a printed circuit board (PCB), in which a circuit is cut off, is electrically and mechanically connected to an upper portion of the printed circuit board 520, so that a circuit is formed at a predetermined temperature or more. A positive temperature element 530 that is broken, a conductive electrode cap 540 that is electrically and mechanically connected to the upper portion of the positive temperature element 530 to apply an actual current to the outside, the safety vent 510, and printing An insulating gasket 550 is formed around the sides of the circuit board 520, the positive temperature element 530, and the electrode cap 540, and insulates the above-mentioned ones from the cylindrical case 400. In this case, the electrode cap 540 is made of any one of the first electrode tab 315 and the second electrode tab 325 of the electrode assembly 300, for example, the first electrode tab 315 is bonded to each other. The same electrode as the first electrode plate 310, for example, serves as a positive terminal.

The wound member 600 is inserted into a space in the center of the wound electrode assembly 300 to prevent the wound electrode assembly 300 from being relaxed and loosened, and the wound electrode assembly 300 by external pressure. It also plays a role in preventing deformation.

The core member 600 is formed by rolling a predetermined metal sheet and is formed in a substantially tubular shape. In addition, the cutting groove 630 is formed along the longitudinal direction of the core member 600. In addition, both side ends of the winding member 600 cutting groove 630 are bent to face the inner direction, and both side ends are bent again to the ends of the winding member 600 toward the outside.

In addition, the core member 600 is preferably formed in the shape of the upper and lower diameter is smaller than the diameter of the central portion.

On the other hand, although not shown in the drawings, the electrolyte is injected into the cylindrical case 400 to enable the movement of lithium ions between the electrode assembly (300). The electrolyte serves as a moving medium of lithium ions (Li Ion) generated by an electrochemical reaction at the positive and negative electrodes inside the battery during charging and discharging, which is a non-aqueous organic electrolyte which is a mixture of lithium salts and high purity organic solvents. Can be. In addition, the electrolyte may be a polymer using a polymer electrolyte, and the type of the electrolyte material is not limited thereto.

Figure 3a is a plan view for explaining the core member for the core member of the cylindrical lithium secondary battery according to an embodiment of the present invention, Figure 3b is a perspective view for explaining the core member of the cylindrical lithium secondary battery according to an embodiment of the present invention. 3C is a cross-sectional view along the CC line of FIG. 3B.

First, referring to FIG. 3A, the core member 600 of the cylindrical lithium secondary battery 200 according to the exemplary embodiment of the present invention is formed using a core member 600 ′ made of a predetermined metal plate.

Each of the core member 600 'includes two first lines each used as a predetermined bending line when the core member 600 is formed along the longitudinal direction of the core member 600' on the left and right sides thereof. 610 ', second line 620' and third line 640 '.

At this time, the core member 600 'is divided into left and right side ends 611 and 615 and a body 613 by the first line 610', and the second line 620 '. Are located in the left and right side ends 611 and 615.

In addition, the third line 640 'is preferably positioned outside the left and right side ends 611 and 615 with respect to the second line 620'.

3B and 3C, the core member 600 of the cylindrical lithium secondary battery 200 according to the exemplary embodiment of the present invention is rolled up a predetermined core member plate 600 ′ as shown in FIG. 3A. Is formed.

The core member 600 is formed in a substantially tubular shape. In addition, the cutting groove 630 is formed along the longitudinal direction of the core member 600.

In addition, the first bent portion 610 that is bent along the first and second lines 610 ′ on the left and right sides of the core member 600 ′, that is, two symmetrical with respect to the cut groove 630. The core member 600 is divided into left and right side ends 611 and 615 and a body portion 613 through the first bent portion 610, and the body portion 613 has an imaginary circumference thereof. It is preferable to form a crust.

In addition, the left and right side ends 611 and 615 are preferably located inside the virtual circumference formed by the extension line of the virtual circumference, particularly the outer circumferential surface of the body portion 613.

In addition, the left and right side ends 611 and 615 of the winding member 600 are connected to the left and right side ends (620) through a second bent part 620 that is bent along the second line 620 ', respectively. It is preferable that the ends of 611 and 615 face the extension lines of the outer surface of the body portion 613 therein. In other words, the left and right side ends 611 and 615 may be formed in a shape bent in a rotational direction opposite to the first bent portion 610 through the second bent portion 620, respectively.

In addition, the left and right side end portions 611 and 615 have a third bent portion 640, the portion of which is located on the outside with respect to the second bent portion 620, bent along the third line 640 '. ) Is made into a rounded shape. In other words, the left and right side end portions 611 and 615 are located outside of the second bent portion 620 based on the second bent portion 620 through the third bent portion 640. ) Is bent in the direction of rotation.

In addition, it is preferable that the ends of each of the left and right side ends 611 and 615 are in contact with an extension line of the outer surface of the body portion 613.

)은 120° 이하인 것이 바람직하다. In addition, the angle between the second bent portions 620 of the left and right side ends 611 and 615 and the surface passing through the central axis of the winding member meets each other (

) Is preferably 120 ° or less.

Accordingly, when the core member 600 is deformed due to the action of external pressure such as longitudinal compression, the electrode assembly 300 is formed by the ends of the left and right side ends 611 and 615 of the core member 600. Can be prevented from being destroyed. In particular, the left and right side ends 611 and 615 break the separator 330 of the electrode assembly 300 due to the deformation of the core member 600, and thus, a short inside the electrode assembly 300 may occur. Can be prevented from occurring.

In addition, the core member 600 is preferably formed in the shape of the upper and lower diameter is smaller than the diameter of the central portion. That is, it is preferable that the upper part and the lower part of the said core member 600 have a predetermined taper part. This prevents damage to the separator 330 by the core member 600 when the core member 600 is inserted into a predetermined space at the center of the electrode assembly 300. Through the upper and lower diameters are made in a form smaller than the diameter of the central portion.

In addition, the core member 600 is formed to about 90% to 110% of the overall height of the electrode assembly 300, the lower end is located on the second electrode tab 325. If the height of the core member 600 is 90% or less of the height of the electrode assembly 300, the force for fixing and supporting the electrode assembly 300 is too weak, and if the height is 110% or more, the cap assembly It is not desirable as it may come into contact with the components of 500.

Figure 4a is a plan view for explaining the core member for the core member of the cylindrical lithium secondary battery according to an embodiment of the present invention, Figure 4b is a perspective view for explaining the core member of the cylindrical lithium secondary battery according to another embodiment of the present invention. 4C is a cross-sectional view taken along the line DD of FIG. 4B.

4A to 4C, the core member 700 of the cylindrical lithium secondary battery 200 according to another embodiment of the present invention may be the core member according to the embodiment of the present invention illustrated in FIGS. 3A to 3C. Structurally similar to 600). However, the left and right side ends 711 and 715 of the winding member 700 are bent through the second bent portion 720, and the ends of the left and right side ends 711 and 715 are wound around the winding member ( Only the structure facing the inner circumferential surface of 700) is different.

In more detail, the core member 700 is formed by rolling a core member plate 700 ′ made of a predetermined metal plate and formed in a substantially tubular shape, and is formed in a cut groove along a longitudinal direction of the core member 700. 710 is formed.

In addition, the left and right side end portions 711 and 715 are formed through the first winding portion 710 which is bent along the first line 710 'of the winding member plate 700'. It is preferable to face inward direction 700).

In addition, each of the left and right side ends 711 and 715 of the winding member 700 may have two second bends bent in the rotation direction of the first bent part 710 along the second line 720 ′. It is preferable that the ends of the left and right side ends 711 and 715 contact the inner circumferential surface of the core member 700 through the portion 720.

In addition, the left and right side end portions 711 and 715 are positioned outside the second bent portion 720 with respect to the second bent portion 720 along the third line 740 '. It is formed in a rounded shape by the third bent portion 740 bent in the rotation direction opposite to the.

)은 120° 이하인 것이 바람 직하다. In addition, the angle between the second bent portion 720 of each of the left and right side ends 711 and 715 and the surface passing through the central axis of the winding member 700 meet each other (

) Is preferably less than 120 °.

5 is a sequential explanatory diagram for explaining a method of manufacturing a cylindrical lithium secondary battery according to one embodiment of the present invention.

Referring to FIG. 5, in the method of manufacturing the cylindrical lithium secondary battery according to the exemplary embodiment of the present invention, the forming step S1 of the electrode assembly 300, the bonding step S2 of the electrode assembly 300, and the core member 600 may be described. ), An insertion step S3, an electrolyte injection step S4, and a coupling step S5 of the cap assembly 500.

6A to 6D are views for explaining a method of manufacturing a cylindrical lithium secondary battery according to one embodiment of the present invention. Hereinafter, a method of manufacturing a cylindrical lithium secondary battery together with FIG. 3 will be described.

Referring to FIG. 6A, first, in the forming step S1 of the electrode assembly 300, the first electrode plate 310, the separator 330, and the second electrode plate 320 are sequentially stacked, and at one end thereof. After the winding shaft 800 is coupled, the coil is wound in a substantially cylindrical shape to form the electrode assembly 300. Of course, before the winding, the first electrode tab 315 is attached to the first electrode plate 310, and the second electrode tab 325 is attached to the second electrode plate 320.

Referring to FIG. 6B, in the coupling step S2 of the electrode assembly 300, the approximately cylindrical electrode assembly 300 is coupled to the cylindrical case 400. Of course, after the coupling, the winding shaft 800 is separated from the electrode assembly 300. In this case, a substantially circular space is formed at the center of the electrode assembly 300. Of course, the winding shaft 800 may be separated in advance before the electrode assembly 300, the present invention is not limited to the order. In addition, a lower insulating plate 341 (not shown) is coupled to the cylindrical case 400 in advance.

Referring to FIG. 6C, in the inserting step S3 of the winding member 600, the winding shaft 800 may be separated to form a space formed at the center of the electrode assembly 300. FIGS. 3A to 3C and 4A to 4C. The core members 600 and 700 as shown in FIG. 4C are inserted.

In the following description, the winding member 600 illustrated in FIGS. 3A to 3C will be described as an example.

Here, any one of the first electrode tab 315 and the second electrode tab 325 of the electrode assembly 300, for example, the second electrode tab 325 before the insertion of the core member 600 may be performed. The lower surface 420 of the cylindrical case 400 may be attached and fixed in advance by a method such as resistance welding. Therefore, the core member 600 is positioned in contact with the upper surface of the second electrode tab 325, and serves to couple the second electrode tab 325 to the cylindrical case 400 more strongly. On the other hand, as described above, the core member 600 is preferably about 90% to about 110% of the height of the electrode assembly 300. That is, when the height of the core member 600 is 90% or less of the electrode assembly 300, the force for fixing and supporting the electrode assembly 300 is too weak, and when the height is 110% or more, the cap assembly It is not desirable to be in contact with the components of 500.

Then, in the electrolyte injection step (S4), the electrolyte is injected to the upper end of the electrode assembly 300. In addition, the electrolyte serves to enable movement of lithium ions during charging and discharging between the first electrode plate 310 and the second electrode plate 320 in the electrode assembly 300.

Referring to FIG. 6D, in the coupling step S5 of the cap assembly 500, the cap assembly 500 including a plurality of components is coupled to the upper portion of the cylindrical case 400 to form the electrode assembly 300 described above. The core member 600 and the electrolyte are prevented from being separated or leaked to the outside, thereby forming the cylindrical lithium secondary battery 200.

In more detail, an insulating ring gasket 550 having a substantially ring shape is coupled to an upper portion of the cylindrical case 400, and then the first electrode tab 315 and the second electrode of the electrode assembly 300 are sequentially disposed therein. The conductive safety vent 510, the printed circuit board 520, the positive temperature element 530, and the electrode cap 540, which are electrically connected to any one of the tabs 325, for example, the first electrode tab 315. Combine sequentially.

Then, by beading the cylindrical case 400 corresponding to the lower end of the insulating gasket 550 to form a beading portion 440 recessed inwardly, and to creep the upper end to form a creeping portion 430, The cap assembly 500 is not separated from the outside to form the cylindrical lithium secondary battery 200.

As described above, the cylindrical lithium secondary battery 200 according to the embodiment of the present invention includes core members 600 and 700 as shown in FIGS. 3A to 3C and 4A to 4C, thereby compressing longitudinal compression and the like. When the core members 600 and 700 are deformed due to the external pressure of the electrode assembly, the electrode assemblies may be formed by the ends of the left and right side ends 611, 615, 711 and 715 of the core members 600 and 700. 300 can be prevented from being destroyed. In particular, the left and right side ends 611, 615, 711, and 715 destroy the separator 330 of the electrode assembly 300 due to the deformation of the core members 600 and 700. ) Short can be prevented from occurring.

As described above, according to the present invention, the present invention can provide a cylindrical lithium secondary battery with improved battery stability against external pressure.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (14)

An electrode assembly including a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, wound in a vortex, and having a predetermined space formed at a winding center thereof; It is formed in a tubular shape formed with a cutting groove along the longitudinal direction, and divided into a body portion and left and right side ends through two first bent portions symmetrical with respect to the cutting groove, and inserted into a central space of the electrode assembly. Lack of core; A case having a space for accommodating the electrode assembly; A cap assembly coupled to the top of the case to seal the cap assembly; An extension line of the outer surface of the body portion of the core member forms an imaginary circumference, The left and right side ends are positioned inside the circumference by the first bent portion, and the left and right side ends are respectively bent in a rotational direction opposite to the first bent portion via a second bent portion. Cylindrical lithium secondary battery. The method of claim 1, The portion located on the outside of the left and right side ends with respect to the second bent portion is bent in the rotation direction of the second bent portion through a third bent portion, characterized in that the cylindrical lithium secondary battery. The method of claim 2, The ends of the left and right side ends are located on an extension line of the outer side of the body portion, the cylindrical lithium secondary battery. The method of claim 1, A cylindrical lithium secondary battery, wherein an angle formed between each of the second bent portions of the left and right side ends and the surface passing through the central axis of the core member is 120 ° or less. The method of claim 1, The cylindrical member is a cylindrical lithium secondary battery, characterized in that the metal material. The method of claim 1, The cylindrical lithium secondary battery, characterized in that the diameter of the upper and lower portions of the core member is smaller than the diameter of the central portion. The method of claim 1, The height of the core member is a cylindrical lithium secondary battery, characterized in that 90% to 110% of the height of the electrode assembly. An electrode assembly including a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, wound in a vortex, and having a predetermined space formed at a winding center thereof; It is formed in a tubular shape formed with a cutting groove along the longitudinal direction, and divided into a body portion and left and right side ends through two first bent portions symmetrical with respect to the cutting groove, and inserted into a central space of the electrode assembly. Lack of core; A case having a space for accommodating the electrode assembly; A cap assembly coupled to the top of the case to seal the cap assembly; An extension line of the body portion of the core member forms an imaginary circumference, The left and right side ends are positioned inside the circumference by the first bent portion, and the left and right side ends are each bent in the rotational direction of the first bent portion through a second bent portion. Lithium secondary battery. The method of claim 8, The cylindrical lithium secondary battery, characterized in that the portion located on the outside of the left and right side end with respect to the second bent portion is bent in a rotational direction opposite to the second bent portion through the third bent portion. The method of claim 9, A terminal of the left and right side ends is in contact with the inner peripheral surface of the body portion, the cylindrical lithium secondary battery. The method of claim 8, A cylindrical lithium secondary battery, wherein an angle formed between each of the second bent portions of the left and right side ends and the surface passing through the central axis of the core member is 120 ° or less. The method of claim 8, The cylindrical member is a cylindrical lithium secondary battery, characterized in that the metal material. The method of claim 8, The cylindrical lithium secondary battery, characterized in that the diameter of the upper and lower portions of the core member is smaller than the diameter of the central portion. The method of claim 8, The height of the core member is a cylindrical lithium secondary battery, characterized in that 90% to 110% of the height of the electrode assembly.

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