KR100670453B1 - Cylindrical Li Secondary Battery - Google Patents

Abstract

The present invention relates to a cylindrical lithium secondary battery with improved stability against the action of external pressure, the cylindrical lithium secondary battery of the present invention is the first electrode plate, the second electrode plate, between the first electrode plate and the second electrode plate An electrode assembly having an interposed separator and having a predetermined space formed in a center thereof; A tubular winding member formed in a tubular shape having a cut groove formed along a longitudinal direction, the protrusion having a predetermined length protruding from the bottom thereof, and coupled to a central space of the electrode assembly; A case having a space for accommodating the electrode assembly, the case having an upper opening; And a cap assembly coupled to the top of the case to seal it.

Lithium secondary battery, core member, protrusion, notch part

Description

Cylindrical Lithium Secondary Battery

1A is a perspective view illustrating a cylindrical lithium secondary battery according to an embodiment of the present invention.

FIG. 1B is a cross sectional view along line A-A in FIG. 1A;

1C is a cross sectional view along line B-B in FIG. 1A;

2A and 2B are perspective views illustrating a core member of a cylindrical lithium secondary battery according to an embodiment of the present invention.

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

4A to 4D 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)

100; Cylindrical lithium secondary battery 200; Electrode assembly

210; First electrode plate 215; First electrode tab

220; Second electrode plate 225; Second electrode tab

230; Separators 241 and 245; Insulation Plate

300; Cylindrical case 310; Cylindrical surface

320; If 330; Creeping Part

340; Beading unit 400; Cap assembly

410; Safety van 420; Printed circuit board

430; Positive temperature element 440; Electrode cap

450; Insulating gasket 500; Absenteeism

510; Incision groove 520; spin

530; Notch

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

In general, a cylindrical lithium ion secondary battery includes an electrode assembly wound in a substantially cylindrical shape, a can of a cylindrical shape to which the electrode assembly is coupled, an electrolyte solution injected into the can to allow movement of lithium ions, and The cap assembly is coupled to one side to prevent leakage of the electrolyte and prevent separation of the electrode assembly.

Since such cylindrical lithium ion secondary batteries usually have a capacity of about 2000 to 2400 mA, they are mainly mounted on note PCs, digital cameras, camcorders, and the like, which require large amounts of electric power. For example, a plurality of cylindrical lithium ion secondary batteries are connected in series and in parallel as many as necessary, and are assembled into a hard pack of a predetermined type with a protection circuit mounted thereon, and are used by being coupled to the electronic device for power supply.

The manufacturing method of such a cylindrical lithium ion secondary battery is as follows.

First, the negative electrode plate on which the predetermined active material layer is formed, the separator and the positive electrode plate on which the predetermined active material layer is formed are laminated together, and then one end is bonded to a rod-shaped winding shaft, and then wound in a substantially cylindrical form to form an electrode assembly. Subsequently, after inserting the electrode assembly into the cylindrical can, the electrolyte is injected, and then the cap assembly is welded to the upper portion of the cylindrical can, thereby completing a substantially cylindrical lithium ion secondary battery.

On the other hand, in recent years, a substantially rod-shaped core member is coupled to the center of the electrode assembly so that the electrode assembly is not deformed during charging and discharging of the lithium ion secondary battery.

However, in the cylindrical lithium secondary battery as described above, the flow of the core member may occur due to an external impact such as a drop. This flow of the core member affects the cap assembly above the core member. In particular, when colliding with the safety vent of the cap assembly, there is a problem that the reversal or destruction of the safety vent occurs. Reversal or destruction of such a safety van can seriously affect the safety of the lithium secondary battery.

In addition, when the core member rotates, there is a problem in that a short occurs at the bottom of the electrode assembly by contacting a lower end of the electrode assembly and the core member.

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 stability to the action of 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, a predetermined space in the center An electrode assembly formed; It is formed in a tubular shape formed with a cutout groove along a longitudinal direction and is coupled to a central space of the electrode assembly. A core member having a protruding protrusion; A case having a space for accommodating the electrode assembly, the case having an upper opening; And a cap assembly coupled to the top of the case to seal it.

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

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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 includes an electrode assembly having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, the predetermined space is formed in the center; It has a tubular shape formed with a cutout groove along the longitudinal direction, and has four notches formed on the circumference of the inner surface of the tubular shape, and an imaginary line connecting each notch portion and an adjacent notch portion is trapezoidal or square. A tubular winding member which is formed and coupled to a central space of the electrode assembly; A case having a space for accommodating the electrode assembly, the case having an upper opening; And a cap assembly coupled to the top of the case to seal it.

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

Like reference numerals in the drawings denote like elements.

1A is a perspective view illustrating a cylindrical lithium secondary battery according to an embodiment of the present invention, FIG. 1B is a cross-sectional view taken along the line A-A of FIG. 1A, and FIG. 1C is a cross-sectional view taken along the line B-B of FIG. 1A.

As illustrated in FIGS. 1A to 1C, the cylindrical lithium secondary battery 100 according to the exemplary embodiment may include an electrode assembly 200 generating a voltage difference during charging and discharging, and accommodating the electrode assembly 200. A cylindrical case 300, a cap assembly 400 assembled on the cylindrical case 300 to prevent the electrode assembly 200 from being separated, and a core member 500 positioned in a central space of the electrode assembly. It consists of a structure provided with).

The electrode assembly 200 may include any one of a positive electrode active material and a negative electrode active material, for example, a first electrode plate 210 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 210 and the second electrode plate 220 is disposed between the coated second electrode plate 220, the first electrode plate 210, and the second electrode plate 220. ) And a separator 230 that allows only lithium ions to move. In addition, the first electrode plate 210, the second electrode plate 220, and the separator 230 are wound in a substantially circular shape and accommodated in the cylindrical case 300. In addition, the first electrode plate 210 is generally made of aluminum (Al) and is bonded to the first electrode tab 215 protruding a predetermined length upward. The second electrode plate 220 is generally made of nickel (Ni), and the second electrode tab 225 protruding to a predetermined length is bonded thereto, but the material of the above is not limited thereto. In addition, upper and lower insulating plates 241 and 245 are further attached to upper and lower portions of the electrode assembly 200 to avoid direct contact with the cap assembly 400 or the cylindrical case 300, respectively.

The cylindrical case 300 has a cylindrical surface 310 having a predetermined space and a predetermined diameter so that the electrode assembly 200 can be coupled, and the cylindrical surface 310 at the lower portion of the cylindrical surface 310. A lower surface 320 is formed to block the lower space of the upper side of the bottom surface. Meanwhile, any one of the first electrode tab 215 and the second electrode tab 225 of the electrode assembly 200 is positioned at the center of the lower surface 320 of the cylindrical case 300, for example, the second electrode tab ( As the 225 is bonded, the cylindrical case 300 itself serves as the same electrode as the second electrode plate 220, for example, a negative electrode terminal. In addition, the cylindrical case 300 is generally formed of aluminum (Al), iron (Fe) or an alloy thereof. In addition, the cylindrical case 300 has a crimping portion 330 that is bent to one side to press the cap assembly 400 at the top thereof, and is inward to press the cap assembly 400 from the bottom to the upper direction. A recessed beading portion 340 is further formed.

The cap assembly 400 has a conductive safety vent 410 in which the shape of the first electrode tab 215 is welded at the same time, the shape is reversed during overcharging or overheating, and an electrical and mechanical structure on the conductive safety vent 410. Connected to the printed circuit board (PCB), which is disconnected when the safety vent 410 is inverted, and is electrically and mechanically connected to an upper portion of the printed circuit board 420 so that the circuit is above a predetermined temperature. The positive temperature element 430 is disconnected, the conductive electrode cap 440 electrically and mechanically connected to the upper portion of the positive temperature element 430 to apply the actual current to the outside, the safety vent 410, A printed circuit board 420, a positive temperature element 430, and an insulating gasket 450 that surrounds the sides of the electrode cap 440 and insulate the above-mentioned ones from the cylindrical case 300. In this case, the electrode cap 440 is bonded to any one of the first electrode tab 215 and the second electrode tab 225 of the electrode assembly 200, for example, the first electrode tab 215 is bonded to each other. The same electrode as the first electrode plate 210 serves, for example, as a positive electrode terminal.

The wound member 500 is inserted into a space in the center of the wound electrode assembly 200 to prevent the wound electrode assembly 200 from being relaxed and loosened, and the wound electrode assembly 200 by external pressure. It also plays a role in preventing deformation. This core member 500 is formed in a substantially tubular shape. In addition, although the cutting groove 510 is formed along the longitudinal direction of the core member 500, the cutting groove 510 is in close contact with the core member 500 when the core member 500 is coupled to the electrode assembly 200. Of course, in some cases, the cutting groove 510 may be maintained at a predetermined distance.

In addition, the core member 500 has a protrusion 520 protruding to a predetermined length in the lower portion, at least one along the longitudinal direction of the core member 500 on the inner surface of the tubular core member 500. A notch portion 530 of is formed.

In addition, the core member 500 is formed to about 90% to 110% of the overall height of the electrode assembly 200, the lower end is located on the second electrode tab 225. If the height of the core member 500 is 90% or less of the height of the electrode assembly 200, the force for fixing and supporting the electrode assembly 200 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 300.

On the other hand, although not shown in the drawings, the electrolyte is injected into the cylindrical case 300 to enable the movement of lithium ions between the electrode assembly 200. 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.

2A and 2B are perspective views illustrating a core member of a cylindrical lithium secondary battery according to an embodiment of the present invention.

2A and 2B, the core member 500 of the cylindrical lithium secondary battery 100 according to the exemplary embodiment of the present invention has a substantially tubular shape, and is cut along the longitudinal direction of the core member 500. 510 is formed.

In addition, the core member 500 is provided with a protrusion 520 protruding at a predetermined length in the lower portion, the tubular core member 500 has a shape of the upper and lower end diameters smaller than the diameter of the central portion Is done. When the core member 500 rotates due to an external pressure, the cutting groove 510 causes components of the electrode assembly 200, that is, the first electrode plate 210 and the second electrode plate ( 220 and the lower part of the separator 230 to prevent the destruction.

In addition, the core member 500 is formed to about 90% to 110% of the overall height of the electrode assembly 200, the lower end is located on the second electrode tab 225. If the height of the core member 500 is 90% or less of the height of the electrode assembly 200, the force for fixing and supporting the electrode assembly 200 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 300.

In addition, at least one notch portion 530 is formed on an inner side surface of the tubular core member 500 along the longitudinal direction of the core member 500. This sets the deformation direction of the core member 500 through the notch 530 in advance, so that when an external pressure of a predetermined pressure or more is applied, the core member 500 is deformed in the set direction, so that the core member 500 This is to prevent the short circuit of the electrode assembly 200 which may occur due to the deformation of.

On the other hand, the notch 530 formed on the inner surface of the core member 500 may be arranged in various forms.

For example, the core member 500 may include two notches 530 formed on the inner side of the core member 500 along the longitudinal direction of the core member 500, as shown in FIG. 2A. have. In this case, the two notches 530 may be arranged symmetrically with respect to the cutting groove 510, and preferably, the two notches 530 may have a circumference based on the cutting groove 510. It is preferably located at 45 ° left and right in the phase.

In other words, the two notches 530 are preferably positioned on the left and right side to have the same distance from the cutting groove 510.

Alternatively, the core member 500 may include four notches 530 formed on the inner surface of the core member 500 along the longitudinal direction of the core member 500, as illustrated in FIG. 2B. The four notches 530 may be symmetrically disposed two by two with respect to the cutting groove 510. Preferably, the four notches 530 are based on the cutting groove 510. It is preferably located at 45 °, 135 °, 225 ° and 315 ° on the circumference.

In other words, the four notches formed on the circumference of the inner surface of the core member 500 are formed in a trapezoidal imaginary line connecting each notch and the adjacent notch, preferably on the circumference of the core member 500. The four notches formed in the structure have a structure in which a virtual line connecting each notch and an adjacent notch forms a square.

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

Referring to FIG. 3, in the method of manufacturing a cylindrical lithium secondary battery according to an embodiment of the present invention, the forming step (S1) of the electrode assembly 200, the bonding step (S2) of the electrode assembly 200, 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 400.

4A to 4D are diagrams for describing 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. 4A, first, in the forming step S1 of the electrode assembly 200, the first electrode plate 210, the separator 230, and the second electrode plate 220 are sequentially stacked, and at one end thereof. After coupling the winding shaft 600, the coil is wound in a substantially cylindrical shape to form the electrode assembly 200. Of course, before the winding, the first electrode tab 215 is attached to the first electrode plate 210, and the second electrode tab 225 is attached to the second electrode plate 220.

Referring to FIG. 4B, in the coupling step S2 of the electrode assembly 200, the approximately cylindrical electrode assembly 200 is coupled to the cylindrical case 300. Of course, after the coupling, the winding shaft 600 is separated from the electrode assembly 200. In this case, a substantially circular space is formed at the center of the electrode assembly 200. Of course, the winding shaft 600 may be separated in advance before the electrode assembly 200, the present invention is not limited to the order thereof. In addition, a lower insulating plate 241 (not shown) is coupled to the cylindrical case 300 in advance.

Referring to FIG. 4C, in the inserting step S3 of the winding member 500, the winding shaft 600 is separated and formed in the center of the electrode assembly 200, as illustrated in FIGS. 2A and 2B. The same core member 500 is inserted.

Here, any one of the first electrode tab 215 and the second electrode tab 225 of the electrode assembly 200 before the insertion of the core member 500, for example, the second electrode tab 225 is The lower surface 320 of the cylindrical case 300 may be attached and fixed in advance by a method such as resistance welding. Therefore, the core member 500 is positioned in contact with the upper surface of the second electrode tab 225, and serves to couple the second electrode tab 225 to the cylindrical case 300 more strongly. On the other hand, as described above, the core member 500 is preferably about 90% to about 110% of the height of the electrode assembly 200. That is, when the height of the core member 500 is 90% or less of the electrode assembly 200, the force for fixing and supporting the electrode assembly 200 becomes too weak, and when the height is 110% or more, the cap assembly It is not desirable to be able to contact the components of 400.

Then, in the electrolyte injection step (S4), the electrolyte is injected to the upper end of the electrode assembly 200. In addition, the electrolyte serves to enable the movement of lithium ions when charging and discharging between the first electrode plate 210 and the second electrode plate 220 in the electrode assembly 200.

Referring to FIG. 4D, in the coupling step S5 of the cap assembly 400, the cap assembly 400 including a plurality of components is coupled to the cylindrical case 300, thereby forming the electrode assembly 200 described above. The core member 500 and the electrolyte solution are prevented from being separated or leaked to the outside, thereby forming the cylindrical lithium secondary battery 100.

In more detail, an insulating gasket 450 having a ring shape is coupled to an upper portion of the cylindrical case 300, and then the first electrode tab 215 and the second electrode of the electrode assembly 200 are sequentially disposed therein. The conductive safety vent 410, the printed circuit board 420, the positive temperature element 430, and the electrode cap 440 electrically connected to any one of the tabs 225, for example, the first electrode tab 215. Combine sequentially.

Then, by beading the cylindrical case 300 corresponding to the lower end of the insulating gasket 450 to form a beading portion 340 recessed in the inward direction, and to creep the upper end to form a creeping portion 330, The cap assembly 400 is not separated from the outside to form the cylindrical lithium secondary battery 100.

As described above, the cylindrical lithium secondary battery 100 according to the embodiment of the present invention has a projection 520 formed on the lower portion of the core member 500 and a longitudinal direction on the inner surface of the core member 500. By providing the formed notch part 530, stability of the said cylindrical lithium secondary battery 100 at the time of an external pressure action improves.

That is, it is possible to prevent the lower portion of the electrode assembly 200, which may occur due to the rotation of the core member 500, through the protrusion formed on the lower portion of the core member 500.

In addition, when an external pressure of a predetermined pressure or more is applied through the notch 530 of the core member 500, the core member 500 may be helically deformed toward the center portion. Therefore, short of the electrode assembly 200 due to deformation of the core member 500 can be prevented.

That is, since the core member 500 includes the protrusion 520 and the notch 530, the stability to the external pressure of the cylindrical lithium secondary battery 100 is improved.

According to the present invention as described above, the present invention can provide a cylindrical lithium secondary battery with improved stability to the action of the 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 (10)

An electrode assembly having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, and having a predetermined space formed in a center thereof; It is formed in a tubular shape formed with a cutout groove along a longitudinal direction and is coupled to a central space of the electrode assembly. A core member having a protruding protrusion; A case having a space for accommodating the electrode assembly, the case having an upper opening; Cylindrical lithium secondary battery comprising a cap assembly coupled to the top of the case and sealing it. delete delete delete The method of claim 1, The said core member is a cylindrical lithium secondary battery characterized by the diameter of an upper part and a lower part being smaller than the diameter of a center part. 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 having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, and having a predetermined space formed in a center thereof; It has a tubular shape formed with a cutout groove along the longitudinal direction, and has four notches formed on the circumference of the inner surface of the tubular shape, and an imaginary line connecting each notch portion and an adjacent notch portion is trapezoidal or square. A tubular winding member which is formed and coupled to a central space of the electrode assembly; A case having a space for accommodating the electrode assembly, the case having an upper opening; Cylindrical lithium secondary battery comprising a cap assembly coupled to the top of the case and sealing it. delete The method of claim 7, wherein The core member is a cylindrical lithium secondary battery, characterized in that further comprising a projection protruding a predetermined length in the lower portion. The method of claim 7, wherein The said core member is a cylindrical lithium secondary battery characterized by the diameter of an upper part and a lower part being smaller than the diameter of a center part.

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