KR20060037828A - Cylindrical li secondary battery - Google Patents

Abstract

The present invention relates to a cylindrical lithium secondary battery having a polygonal cross-sectional shape of the core member to improve resistance to external pressure of the core member, thereby improving safety. The cylindrical lithium secondary battery of the present invention includes a first electrode plate and a second electrode. A wound electrode assembly having a plate, a separator interposed between the first electrode plate and the second electrode plate; A tubular winding member inserted into the winding portion of the wound electrode assembly and having a polygonal cross section; A case having a space for accommodating the electrode assembly; And a cap assembly coupled to the top of the case to seal it.

Lithium secondary battery, core member, polygon

Description

Cylindrical Lithium Secondary Battery

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

Figure 2a is a perspective view for explaining the 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;

3A to 3C are diagrams for explaining a core member of 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; Side panels

420; Bottom plate 430; Creeping Part

440; Beading unit 500; Cap assembly

510; Safety van 520; Printed circuit board

530; Positive temperature element 540; Electrode cap

550; Insulating gasket 600; Electrolyte

700; Core member 710; Incision groove

The present invention relates to a cylindrical lithium secondary battery, and more particularly, to a cylindrical lithium secondary battery having improved safety by improving the resistance to external pressure of the core member by making the cross-sectional shape of the core member polygonal.

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 expanding 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 to form a tubular shape having 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 pointed shape in which the upper end and the lower end of the cut-out portion in the longitudinal direction are inserted into the electrode assembly, in particular, the separator during insertion of the core member 100 or flow of the core member 100. There is a problem of damage.

In addition, the core member 100 may be easily deformed or deformed by deformation such as compression by external pressure, thereby destroying the separator of the electrode assembly. The destruction of the separator may be caused by the anode electrode plate and the cathode electrode. There is a fatal problem that may cause a short between the plates, which may cause destruction or explosion of the cylindrical lithium secondary battery.

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 safety by improving the resistance to the external pressure of the core member by the polygonal cross-sectional shape of the core member Its purpose is to.

Cylindrical lithium secondary battery of the present invention for achieving the above object comprises a wound electrode assembly having a separator interposed between the first electrode plate, the second electrode plate, the first electrode plate and the second electrode plate; A tubular winding member inserted into the winding portion of the wound electrode assembly and having a polygonal cross section; A case having a space for accommodating the electrode assembly; And a cap assembly coupled to the top of the case to seal it.

The core member may have any one of a cross section, a rectangle, a pentagon, and a hexagon.

In addition, the core member may be formed in a tubular shape in which a portion is cut along the longitudinal direction, and the cut portion may be formed in a shape in which the wound member is wound in an inner direction of the core member.

A lower insulating plate may be positioned between the electrode assembly and the lower surface of the case, and an upper insulating plate may be positioned between the electrode assembly and the cap assembly.

One of the first electrode plate and the second electrode plate may be electrically connected to the lower lower surface of the case through an electrode tab, and the winding member may be positioned on an electrode tab electrically connected to the lower surface.

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, and FIG. 2B is a cross-sectional view taken along the line A-A of FIG. 2A.

As shown in FIGS. 2A and 2B, the cylindrical lithium secondary battery 200 according to the exemplary embodiment of the present invention includes an electrode assembly 300 that generates a voltage difference when charging and discharging, and accommodates 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 injected into the cylindrical case 400 so that the electrode assembly 300 is closed. ) And an electrolyte solution 600 capable of allowing lithium ions to move, and a core member 700 positioned in a central space of the electrode assembly.

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 210, the second electrode plate 320, and the separator 330 are wound in a substantially circular shape and accommodated in the cylindrical case 400. 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 the material 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 side plate 410 having a predetermined diameter and a predetermined diameter so that the cylindrical electrode assembly 300 can be coupled, and the cylindrical side plate 410 has a lower portion of the cylindrical side plate 410. A lower plate 420 is formed to block a lower space of the side plate 410, and an upper portion of the cylindrical side plate 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 plate 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 may be electrically and mechanically mounted on the conductive safety vent 510 and the conductive safety vent 510 at which the first electrode tab 315 is welded and at the same time, the shape of the cap is reversed upon overcharge or overheating. Connected to a printed circuit board (PCB) that is disconnected when the safety vent 510 is inverted, and is electrically and mechanically connected to an upper portion of the printed circuit board 520 to provide a circuit at a predetermined temperature or more. The positive temperature element 530 is disconnected, the conductive electrode cap 540 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, It consists of an insulating gasket 550 that wraps around the sides of the printed circuit board 520, the positive temperature element 530, and the electrode cap 540 and insulates those listed 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 electrolyte 600 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 material that is a mixture of lithium salts and high purity organic solvents. The organic electrolyte may be. In addition, the electrolyte 600 may be a polymer using a polymer electrolyte, and the electrolyte 600 is not limited thereto.

The core member 700 is formed in a tubular shape having a polygonal cross section, thereby improving resistance to external pressure, thereby minimizing deformation when the external pressure is applied. The core member 700 is inserted into a space in the center of the wound electrode assembly 300, so that the second electrode tab 325 of the electrode assembly 300 is disposed on the lower surface plate 420 of the cylindrical case 400. When welding to the center portion of the, the pressure is applied to the second electrode tab 325 serves to make the second electrode tab 325 in contact with the lower surface plate 420 of the cylindrical case 400. In addition, the wound member 700 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 due to external pressure ( It also serves to prevent deformation of the 300).

3A to 3C are diagrams for explaining a core member of a cylindrical lithium secondary battery according to one embodiment of the present invention.

3A to 3C, the core member 700 of the cylindrical lithium secondary battery according to the exemplary embodiment of the present invention has a tubular shape having a cutting groove 710 formed along a length direction, and the cutting groove Both side ends of the 710 are made to face the inner direction of the core member 700.

In addition, the core member 700 has a cross section of the core member 700 having a polygonal shape.

For example, the core member 700 may have a polygonal shape such that its cross-sectional shape is a quadrangular shape as in FIG. 3A, a pentagonal shape as in FIG. 3B, or a rectangular shape as in FIG. 3C.

As described above, the tubular core member 700 having a polygonal cross section has a greater resistance to external pressure than the tubular core member having a circular cross section. This is because the angled part of the polygon in the cross section is more resistant to external pressure than other parts. Therefore, this can minimize the deformation of the core member 700 by external pressure by making the core member 700 have a polygonal cross sectional shape.

The cylindrical lithium secondary battery 200 including the core member 700 as described above is formed through the following process.

First, the first electrode plate 310, the separator 330, and the second electrode plate 320 are sequentially stacked, and one end thereof is coupled with a winding shaft for winding the electrode assembly 300, and then 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.

After the electrode assembly 300 is formed, the approximately cylindrical electrode assembly 300 is coupled to the cylindrical case 400. Of course, after the coupling, the winding shaft is separated from the electrode assembly 300, and at this time, a substantially circular space is formed at the center of the electrode assembly 300. Of course, the winding shaft may be separated in advance before the electrode assembly 300, the present invention is not limited to the order thereof. In addition, a lower insulating plate 341 is coupled to the cylindrical case 400 in advance.

After the electrode assembly 300 is coupled to the cylindrical case 400, the winding shaft is separated and the core member 700 having a polygonal cross-sectional shape in a space formed at the center of the electrode assembly 300. Insert

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 700 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 700 is positioned in contact with the upper surface of the second electrode tab 325, and serves to more strongly couple the second electrode tab 325 to the cylindrical case 400. On the other hand, as described above, the core member 700 is preferably about 90% to about 110% of the height of the electrode assembly 300. This is because the height of the core member 700 is 90% or less 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 ( This is because it is possible to come into contact with the components of 500).

After the core member 700 is inserted, the electrolyte 600 is injected to the upper end of the electrode assembly 300. In addition, the electrolyte 600 serves to enable the 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.

Then, by combining the cap assembly 500 consisting of a plurality of components on the cylindrical case 400, the above-described electrode assembly 300, the core member 700 and the electrolyte 600 is separated or leaked to the outside The cylindrical lithium secondary battery 200 is formed so as not to.

In more detail, the insulating gasket 550 having a ring shape is coupled to the 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 inside. 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.

In the cylindrical lithium secondary battery 200 of the present invention as described above, since the cross-sectional shape of the core member 700 has a polygonal shape, the core member 700 may minimize deformation due to external pressure, By preventing the breakage of the separator 330, a short between the first electrode plate 310 and the second electrode plate 320 of the electrode assembly 300 may be prevented.

Accordingly, the cylindrical lithium secondary battery 200 includes a tubular core member 700 having a polygonal cross section thereof, thereby improving safety against external pressure.

According to the present invention as described above, the present invention can provide a cylindrical lithium secondary battery with improved safety by improving the resistance to external pressure of the core member by making the cross-sectional shape of the core member into a polygonal shape.

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 (5)

A wound electrode assembly having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate; A tubular winding member inserted into the winding portion of the wound electrode assembly and having a polygonal cross section; A case having a space for accommodating the electrode assembly; Cylindrical lithium secondary battery comprising a cap assembly coupled to the top of the case and sealing it. The method of claim 1, The core member is a cylindrical lithium secondary battery, characterized in that the cross section is any one of a rectangle, a pentagon and a hexagon. The method of claim 1, The core member is made of a tubular shape cut in part along the longitudinal direction, A cylindrical lithium secondary battery, characterized in that the cut portion is formed in a shape that is wound in the inner direction of the core member. The method of claim 1, And a lower insulating plate disposed between the electrode assembly and the lower surface of the case, and an upper insulating plate disposed between the electrode assembly and the cap assembly. The method of claim 1, Any one of the first electrode plate and the second electrode plate is electrically connected to the lower lower surface of the case through an electrode tab, the winding member is positioned on an electrode tab electrically connected to the lower surface Lithium secondary battery.

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