KR20070097146A - Secondary battery - Google Patents

Abstract

A secondary battery is provided to minimize the movement of an electrode assembly inside a can when the battery is used, thereby inhibiting an increase in internal resistance of the battery. A secondary battery includes a jelly roll type electrode assembly(20), a can(10) for accommodating the electrode assembly, and a cap assembly(100) which combines with the opened top of the can. A cross-sectional outside diameter of an electrode assembly-taping member assembly(60) is the smallest at the lower part, wherein the electrode assembly-taping member assembly has a taping member(50) for fixing a wound end of the electrode assembly. The largest outside diameter of cross-sectional outside diameters of the electrode assembly-taping member assembly corresponds to the inside diameter of the can.

Description

Secondary Battery {SECONDARY BATTERY}

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

FIG. 2 is a front sectional view of the secondary battery shown in FIG. 1;

3 is a schematic view showing a state before the taping member is attached to the electrode assembly of the secondary battery shown in FIG.

4 to 11 is a schematic view showing an electrode assembly-tapping member assembly of a secondary battery according to each embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: can 20: electrode assembly

50, 50 ', 50 ": taping member 51: first adhesive tape

52: second adhesive tape 53: third adhesive tape

60: electrode assembly-tapping member assembly

100: cap assembly

The present invention relates to a secondary battery, and more particularly, to a secondary battery in which an increase in internal resistance (IR) of a battery is minimized by minimizing flow of an electrode assembly in a can when a battery is used.

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.

Among these, the cylindrical secondary battery includes an electrode assembly, a cylindrical can housing the electrode assembly, and a cap assembly coupled to an upper portion of the can.

In the electrode assembly, a cathode, a cathode, and a separator interposed between the two electrodes are wound in a cylindrical shape to form a jelly roll, and anode and cathode tabs are drawn out from the anode and the cathode, respectively. Normally, the positive electrode tab is upward and the negative electrode tab is pulled out downward.

The can is a metal container having a substantially cylindrical shape in a cylindrical secondary battery, and is formed by a processing method such as deep drawing. Thus, it is also possible for the can itself to serve as a terminal.

The cap assembly is coupled to the open top of the can, with a gasket insulated between the cap assembly and the can.

The positive electrode of the electrode assembly is electrically connected to one part of the cap assembly through an upwardly drawn positive electrode tab, and the negative electrode is joined to the bottom surface of the can through a negatively negative tab drawn downward. Of course, the polarity can also be changed.

In addition, between the electrode assembly and the cap assembly, an upper insulation member for insulation of the two is positioned, and a lower insulation member for insulation of the two is positioned between the electrode assembly and the bottom surface of the can.

A secondary battery having such a structure can be placed in various environments as a power source for electrical and electronic equipment. For example, the secondary battery may be used as a power source for a power tool such as a drill. Since the power tool often requires instantaneous power, the smaller the internal resistance IR of the battery is, the better.

However, since the external tool such as vibration is severely impacted by the power tool, the electrode assembly may frequently flow within the can of the battery due to such vibration or impact. This flow increases the resistance inside the cell and damages the welded areas of the positive electrode tab welded to one part of the cap assembly or the negative electrode tab welded to the bottom of the can, thereby reducing the reliability of the cell.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to suppress an increase in internal resistance of a battery by minimizing the flow of an electrode assembly in a can when a battery is used.

Secondary battery according to the present invention for achieving this object,

An electrode assembly wound in the shape of a jelly roll, a can housing the electrode assembly, and a cap assembly coupled to an open upper portion of the can assembly, wherein the tape assembly is fixed to the winding end of the electrode assembly. The cross-sectional outer diameter of the electrode assembly-tapping member assembly is the smallest at the bottom thereof, and the largest outer diameter of the cross-sectional outer diameter of the electrode assembly-tapping member assembly corresponds to the inner diameter of the can.

Here, the outer diameter of the electrode assembly-tapping member assembly is preferably the largest at the top.

In this case, the taping member may include a plurality of adhesive tapes having the same thickness, and the number of overlaps of the taped adhesive tapes may be reduced from the upper portion of the electrode assembly downward.

Alternatively, the taping member may include a plurality of adhesive tapes having different thicknesses, and the upper portion of the electrode assembly may be taped with a thicker adhesive tape than the lower portion thereof.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 and 2, the cylindrical secondary battery includes an electrode assembly 20, a can 10 containing the electrode assembly 20, and a cap assembly 100 coupled to the can 10. .

The electrode assembly 20 typically forms two different electrodes 25 in a wide plate shape in order to increase capacitance, and thereafter, the separators 21 and 23 are insulated from each other to be stacked between the two electrodes 25. It is wound 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. 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 and 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. Meanwhile, the tapering member 50 is attached to the winding end of the electrode assembly 20 to prevent loosening of the electrode assembly 20 wound in a jelly roll shape, which will be described later.

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. In the cylindrical can 10, a lower insulating member 30, an electrode assembly 20, and an upper insulating member 40 are sequentially installed. 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 member 30 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. On the other hand, the upper insulating member 40 serves to insulate between the upper surface of the electrode assembly 20 and the cap assembly 100.

In the cylindrical can 10 in which the lower insulating member 30, the electrode assembly 20, and the upper insulating member 40 are accommodated, the outside of the can 10 of the upper portion of the upper insulating member 40 is formed on the outside. By pressing inwards to form the beading portion 15, the flow of the electrode assembly 20 is prevented.

Thereafter, the electrolyte is 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.

As shown in the cap assembly 100, the vent 110, the current breaker 120, the PTC 130, and the cap up 140 are located in order from the bottom. Vent 110 is located at the bottom of the cap assembly 100, the central portion of the event 110 has a protrusion 112 is convexly protruded downward and electrically connected to the electrode tab 27. A current interrupter (CID) 120 is formed above the vent 110 so that the protrusion 112 of the vent 110 is broken by being convexly deformed by the internal pressure. A PTC (Positive Thermal Coefficient) 130 is provided above the current breaker 120, which blocks the flow of current in the battery by overheating of the battery. A cap up 140 having an electrode terminal formed convexly formed to be electrically connected to the outside is provided above the PTC.

The gasket 150 is positioned between the upper portion of the can 10 and the cap assembly 100 to seal and insulate the can 10 from the cap assembly 100. The gasket 150 is placed on the open upper portion of the can 10 and placed over the beading portion 15. Then, the cap assembly 100 is placed on the opening of the gasket 150 and the upper end of the can 10 is pressed. A crimping portion that is bent inwardly forms a seal between the can 10 and the cap assembly 100.

On the other hand, the method and the structure of the winding end of the electrode assembly 20 with the taping member 50 in more detail as follows.

Referring to FIG. 1, the cross-sectional outer diameter of the electrode assembly-tapping member assembly 60 in which the taping member 50 fixing the winding end of the electrode assembly 20 is attached is the smallest at the lower portion thereof, and the outer diameter thereof is upwardly upward. This increase is largest at the top of the assembly 60 and the outer diameter at the top of the assembly 60 having the largest outer diameter of the cross-sectional outer diameter of the assembly 60 corresponds to the inner diameter of the can 10.

Here, the electrode assembly-tapping member assembly 60 is a tape member 50 attached to the winding end of the electrode assembly 20 in order to prevent loosening of the electrode assembly 20 wound in a jelly roll shape, and the electrode assembly ( Refers to the combination of 20).

The reason for the smallest outer diameter at the bottom of the assembly 60 is to facilitate the insertion of the assembly 60 into the can 10.

In addition, the outer diameter at the upper part of the assembly 60 is maximized, and the reason for making the outer diameter correspond to the inner diameter of the can 10 is, in inserting the assembly 60 into the can 10, the assembly After loosely inserting the lower and middle portions of the 60, the upper portion is inserted tightly without any free space, so that the assembly 60 does not flow inside the can due to external vibration or impact. Thus, internal resistance of the battery is minimized.

Although not shown, in the cross-sectional outer diameter of the electrode assembly-tapping member assembly, the outer diameter of the lower part of the assembly may be the smallest to facilitate insertion, and the outer diameter of the middle portion of the assembly may be the largest to prevent flow. However, there is a disadvantage that the insertion of the intermediate portion of the assembly is not easy.

On the other hand, there may be a variety of ways to taper so that the outer diameter at the top of the assembly 60 is the largest and the outer diameter is smaller toward the lower side.

First, the taping member 50 may include a plurality of adhesive tapes having the same thickness, but a method of reducing the number of overlaps of the taped adhesive tapes from the upper portion of the electrode assembly 20 toward the lower side may be considered. This method again has two methods, one is to control the number of overlapping the plurality of adhesive tapes of different width, the other is to adjust the number of overlapping by the same width of the plurality of adhesive tapes to be. Examples using the former method are shown in FIGS. 3 to 9, and examples using the latter method are shown in FIG. 10.

Referring to FIG. 3, the taping member 50 includes a first adhesive tape 51 having the thinnest width, a second adhesive tape 52 having a middle width, and a third adhesive tape 53 having the largest width. And upper ends of the first to third adhesive tapes 51 to 53 are positioned to correspond to the upper ends of the electrode assembly 20.

At this time, the width of the third adhesive tape 53 corresponds to the upper and lower lengths of the electrode assembly 20, and the width 52 of the second adhesive tape is about 2/3 of the width of the third adhesive tape 53. The width of the first adhesive tape 51 is about 1/3 of the width of the third adhesive tape 53. However, the content of the present invention is not limited thereto.

Referring to FIG. 4, in the first embodiment, the taped order of the electrode assembly 20 is in the order of the first adhesive tape 51, the second adhesive tape 52, and the third adhesive tape 53. Here, the length of the first to third adhesive tapes 51 to 53 may be such that the length can be wound around the cylinder, even in the following embodiments.

Referring to FIG. 5, in the second embodiment, the taped order of the electrode assembly 20 is in the order of the first adhesive tape 51, the third adhesive tape 53, and the second adhesive tape 52.

Referring to FIG. 6, in the third embodiment, the taped order of the electrode assembly 20 is in the order of the second adhesive tape 52, the third adhesive tape 53, and the first adhesive tape 51.

Referring to FIG. 7, in the fourth embodiment, the taped order of the electrode assembly 20 is in the order of the second adhesive tape 52, the first adhesive tape 51, and the third adhesive tape 53.

Referring to FIG. 8, in the fifth embodiment, the taped order of the electrode assembly 20 is in the order of the third adhesive tape 53, the second adhesive tape 52, and the first adhesive tape 51.

Referring to FIG. 9, in the sixth embodiment, the taped order of the electrode assembly 20 is in the order of the third adhesive tape 53, the first adhesive tape 51, and the second adhesive tape 52.

Meanwhile, referring to FIG. 10, as a seventh embodiment, the width 50 'of the taping member is the same, but the width thereof is equal to or less than 1/2 of the upper and lower lengths of the electrode assembly 20. The taping member 50 ′ includes a plurality of adhesive tapes having the same thickness and the same width. The taping member 50 ′ is wound around three layers at the top of the electrode assembly 20, two layers at the middle, and one layer at the bottom.

Next, referring to FIG. 11, as an eighth embodiment, the taping member 50 "includes a plurality of adhesive tapes having different thicknesses, and the upper portion of the electrode assembly 20 has a thicker thickness than the lower portion thereof. Taped with adhesive tape.

As discussed in the above first to eighth embodiments, the outer diameter of the electrode assembly-tapping member assembly is smaller from the top to the bottom. In addition, the outer diameter of the upper part of the assembly having the largest outer diameter is equal to or slightly larger than the inner diameter of the cylindrical can, and then tightly inserted to prevent the assembly from flowing inside the can. Therefore, the increase in the internal resistance of the battery due to external vibration or shock can be suppressed.

According to the present invention, the outer diameter of the lower part of the assembly is the smallest among the cross-sectional outer diameters of the electrode assembly-tapping member assembly in which the taping member for fixing the winding end of the electrode assembly is attached to facilitate insertion of the assembly into the can. The inner diameter of the battery can be suppressed from being increased by external vibration or shock by preventing the flow in the can of the assembly by matching the largest outer diameter of the cross-sectional outer diameter of the assembly to the inner diameter of the cylindrical can. .

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 (14)

An electrode assembly wound in a jellyroll shape; A can containing the electrode assembly; And a cap assembly coupled to the open top of the can, The cross-sectional outer diameter of the electrode assembly-tapping member assembly in which the taping member fixing the winding end of the electrode assembly is attached is the smallest at the bottom thereof, and the largest outer diameter of the cross-sectional outer diameter of the electrode assembly-tapping member assembly is A secondary battery characterized by corresponding to the inner diameter. The method of claim 1, Secondary battery, characterized in that the outer diameter of the electrode assembly-tapping member assembly is the largest at the top. The method of claim 2, The taping member includes a plurality of adhesive tapes having the same thickness, secondary battery characterized in that the number of overlap of the adhesive tape taped toward the lower side from the top of the electrode assembly. The method of claim 3, wherein The taping member may include a first adhesive tape having the thinnest width, a second adhesive tape having a middle width, and a third adhesive tape having the largest width, wherein upper ends of the first to third adhesive tapes are formed in the electrode assembly. Secondary battery, characterized in that positioned so as to correspond to the top. The method of claim 4, wherein The width of the third adhesive tape corresponds to the upper and lower lengths of the electrode assembly, the width of the second adhesive tape is about 2/3 of the width of the third adhesive tape, and the width of the first adhesive tape is A secondary battery, characterized in that about 1/3 of the width of the third adhesive tape. The method of claim 4, wherein The taped order of the electrode assembly is a secondary battery, characterized in that the first adhesive tape, the second adhesive tape, the third adhesive tape in the order. The method of claim 4, wherein The taped order of the electrode assembly is a secondary battery, characterized in that the first adhesive tape, the third adhesive tape, the second adhesive tape in the order. The method of claim 4, wherein The order in which the taped to the electrode assembly is a second adhesive tape, the third adhesive tape, the first adhesive tape, characterized in that in order. The method of claim 4, wherein The order in which the taped to the electrode assembly is a second adhesive tape, the first adhesive tape, the third adhesive tape, characterized in that in order. The method of claim 4, wherein The taped order of the electrode assembly is a secondary battery, characterized in that the order of the third adhesive tape, the second adhesive tape, the first adhesive tape. The method of claim 4, wherein The taped order of the electrode assembly is a secondary battery, characterized in that the order of the third adhesive tape, the first adhesive tape, the second adhesive tape. The method of claim 3, wherein The width of the taping member is the same, the width of the secondary battery, characterized in that less than 1/2 of the upper and lower lengths of the electrode assembly. The method of claim 2, The taping member includes a plurality of adhesive tapes having different thicknesses, wherein the upper part of the electrode assembly is tapered with a thicker adhesive tape than the lower portion thereof. The method according to any one of claims 1 to 13, Secondary battery, characterized in that the outer shape of the electrode assembly and the can is cylindrical.

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