KR100670441B1 - Secondary battery - Google Patents

Abstract

Provided is a secondary battery, wherein an electrolytic solution easily diffuses toward the upper part through the bottom of an electrode assembly, and thus the electrode assembly is sufficiently impregnated with an electrolytic solution and an impregnation time is reduced. The secondary battery comprises an electrode assembly(20), a can(10) for accommodating the electrode assembly(20) and an electrolytic solution, a lower insulation member(30) interposed between the electrode assembly(20) and the bottom of the can(10), and a cap assembly(100) to be combined with the upper part of the can(10). An uneven part is formed on the upside of the lower insulation member(30). The underside of the lower insulation member(30) is flat.

Description

Secondary Battery {SECONDARY BATTERY}

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

Figure 2a is a perspective view showing a lower insulating member of a cylindrical secondary battery according to an embodiment of the present invention, Figure 2b is a cross-sectional view A-A of Figure 2a,

Figure 3a is a perspective view showing a lower insulating member of a cylindrical secondary battery according to another embodiment of the present invention, Figure 3b is a cross-sectional view B-B of Figure 3a,

4A is a perspective view illustrating a lower insulating member of a cylindrical secondary battery according to still another embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along line C-C of FIG. 4A.

Explanation of symbols on the main parts of the drawings

10: can 20: electrode assembly

30, 30 ', 30 ": lower insulation member 31: uneven portion

32: convex portion 33: concave portion

34: convex part 35: hole

36: protrusion 37: hole

39, 39 ', 39 ": Center hole 100: Cap assembly

The present invention relates to a secondary battery, and more particularly, to the shape of a lower insulating member for securing an electrolyte impregnation route to the lower electrode assembly.

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 positive electrode and a negative electrode and a separator interposed between the two electrodes are wound in a cylindrical shape, and the positive and negative electrode tabs are drawn out from the positive and negative electrodes, 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. It is therefore possible for the can itself to act 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.

Also, between the bottom of the electrode assembly and the bottom of the can is a disc-shaped lower insulating member for insulating the two.

However, the conventional lower insulating member has a structure in which the portion in contact with the bottom surface of the electrode assembly is flat. Accordingly, the bottom surface of the electrode assembly, the bottom insulating member, and the bottom surface of the can are in close contact with each other so that there is no space for the electrolyte to accumulate.

Therefore, it is difficult to diffuse the electrolyte upward through the bottom of the electrode assembly, and there is a problem in that the electrode assembly is not sufficiently impregnated with the electrolyte, and the impregnation time takes a long time.

The present invention has been made to solve the above problems, and an object thereof is to design a shape of a lower insulating member for securing an electrolyte impregnation route under the electrode assembly.

A secondary battery according to an aspect of the present invention for achieving the above object,

Electrode assembly; A can containing the electrode assembly and the electrolyte; A lower insulating member positioned between the electrode assembly and the bottom surface of the can; And a cap assembly coupled to the open upper portion of the can, wherein an uneven portion is formed on an upper surface of the lower insulating member.

In this case, a plurality of holes may be formed in the lower insulating member.

On the other hand, the secondary battery according to another aspect of the present invention for achieving the above object,

Electrode assembly; A can containing the electrode assembly and the electrolyte; A lower insulating member positioned between the electrode assembly and the bottom surface of the can; And a cap assembly coupled to the open upper portion of the can, wherein a plurality of protrusions are formed on an upper surface of the lower insulating member.

In this case, a plurality of holes may be formed in the lower insulating member.

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

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

Referring to the drawings, the cylindrical secondary battery includes an electrode assembly 20, a can 10 for receiving the electrode assembly 20 and an electrolyte, 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, separators 21 and 23 are insulated from each other and positioned below or above the two electrodes. It is then laminated, rolled up in a circle to form a so-called 'Jelly Roll'. The two electrode plates are formed by coating an active material slurry on a current collector made of metal foil or metal mesh made of aluminum and copper, respectively. In the direction in which the electrode plate is wound, there is a non-coated portion at which the slurry is not applied at the start end and the end of the current collector. In the uncoated portion, electrode tabs 27 and 29 are provided one by one in the electrode plate, and the electrode tabs may be formed to be pulled out of the electrode one upward in the direction of the opening of the cylindrical can and the other downward, or both tabs. It may be formed to be drawn upward in the opening direction.

The can 10 has a cylindrical shape as shown, is a container made of a lightweight conductive metal such as aluminum or an aluminum alloy, and is formed by a processing method such as deep drawing. In the cylindrical can 10, a disk-shaped 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 bottom surface of the electrode assembly 20 so that the bottom surface of the electrode assembly 20 is not short-circuited with the bottom surface of the can 10. The structure of the lower insulating member 30 will be described later. 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. It is possible to prevent the flow of the electrode assembly 20 by forming the beading portion 15 by pressing inward.

Thereafter, the electrolyte is injected into the cylindrical can 10. The injection of the electrolyte may be performed by first vacuuming the inside of the can 10 and then injecting the electrolyte with a certain amount of pressure. 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.

A 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 structure of the lower insulating member 30 is as follows.

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

Referring to the drawings, the lower insulating member 30 of the secondary battery according to an embodiment of the present invention is formed with an uneven portion 31 on the upper surface.

1, 2A and 2B, the electrolyte is injected through the top of the open can 10 before the cap assembly 100 is coupled to the open top of the cylindrical can 10. Some of the injected electrolyte solution is impregnated downward from the upper surface of the electrode assembly 20, and the rest flows downward along the side of the electrode assembly 20.

In the present exemplary embodiment, since the bottom surface of the electrode assembly 20 and the lower insulating member 30 are not in close contact with each other due to the uneven portion 31, the electrolyte that flows downward along the side of the electrode assembly 20 is uneven. It is possible to accumulate in the recessed part 33 of the part 31, or to move laterally through the recessed part 33. FIG. Therefore, diffusion of the electrolyte solution upward through the bottom of the electrode assembly 20 can be facilitated, so that the electrolyte solution can be sufficiently impregnated with the electrode assembly 20, and the impregnation time can be shortened.

At this time, the lower surface of the lower insulating member 30 is preferably flat. If an uneven portion is formed on the lower surface of the lower insulating member 30 and the lower surface is bent, the electrolyte solution accumulates between the bottom surface of the can 10 and the curved portion of the lower insulating member 30 and the impregnation of the electrode assembly 20. This is because useless electrolyte solution which cannot contribute contributes to the inside of the can 10. In addition, if the lower surface of the lower insulating member 30 is bent, the length of the electrode assembly to be accommodated in the same can size is reduced, which may cause a decrease in battery capacity.

In addition, it is preferable that the convex portion 32 of the uneven portion 31 is located in a region other than the edge portion of the lower insulating member 30. If the convex portion of the concave and convex portions is located at the edge of the lower insulating member 30, when the electrolyte flowing downward along the side of the electrode assembly 20 tries to move sideways by turning the 90 ° direction, the convex portion It can act as a barrier.

3A and 3B, the lower insulating member 30 ′ of the secondary battery according to another exemplary embodiment of the present invention has an uneven portion formed on an upper surface thereof, and a plurality of holes 35 in the lower insulating member 30 ′. ) Is formed. Accordingly, the electrolyte flowing downward along the side of the electrode assembly can move to the bottom surface of the electrode assembly through a plurality of holes 35 formed in the lower insulating member 30 '. However, since the size of the hole 35 is too large, it is necessary to be careful not to cause a short circuit between the bottom surface of the can and the bottom surface of the electrode assembly.

The hole 35 is preferably formed in a portion where the convex portion 34 is not formed among the uneven portions. If a hole is formed in the convex portion 34, it is contrary to the object of the present invention to form an uneven portion on the upper surface of the lower insulating member to secure the electrolyte impregnation route.

The hole 35 is formed in a portion of the concave-convex portion, so that in the embodiment shown in Figs. 2A and 2B, the electrolyte is accumulated in the concave portion, but in this embodiment, the electrolyte may be accumulated in the hole 35. do. Therefore, the electrolyte can be easily diffused upward through the bottom of the electrode assembly, so that the electrolyte can be sufficiently impregnated with the electrode assembly, and the impregnation time can be shortened. However, the holes may not be formed in all of the recesses in the present embodiment, and thus the recesses and the holes may coexist.

4A and 4B, a plurality of protrusions 36 are formed on an upper surface of a lower insulating member 30 ″ of a secondary battery according to another exemplary embodiment of the present invention.

The role of the protrusion 36 is the same as that of the convex portion among the uneven portions in the above-described embodiments. That is, in the present embodiment, the protrusion 36 frees the movement of the electrolyte by preventing the bottom surface of the electrode assembly and the lower insulating member 30 ″ from coming into close contact with each other.

In addition, it is preferable that the lower surface of the lower insulating member 30 "is flat. This is to prevent the electrolyte from accumulating between the bottom surface of the can and the lower insulating member lower surface.

In addition, it is preferable that the protrusions 36 are located in an area other than the edge of the lower insulating member 30 ". This is to prevent the protrusions 36 from acting as a barrier against the movement of the electrolyte.

In addition, a plurality of holes 37 are formed in the lower insulating member 30 ". Accordingly, the electrolyte at the bottom of the can flows downward along the side of the electrode assembly to the lower insulating member 30". It is possible to move toward the bottom of the electrode assembly through a plurality of holes 37 formed.

In this case, the hole 37 is preferably formed in a portion where the protrusion 36 is not formed. If a hole is formed in the projection 36, it is contrary to the object of the present invention to secure the electrolyte impregnation route by forming a projection on the upper surface of the lower insulating member.

According to the present invention, by forming an uneven portion on the upper surface of the lower insulating member insulated between the electrode assembly and the bottom surface of the can, the bottom surface of the electrode assembly and the lower insulating member do not adhere to each other, and flow downward along the side of the electrode assembly. The lowered electrolyte solution is accumulated in the concave portion of the concave and convex portions, and can move laterally through the concave portions. Therefore, the electrolyte can be easily diffused upward through the bottom of the electrode assembly, so that the electrolyte can be sufficiently impregnated with the electrode assembly, and the impregnation time can be shortened. The same applies to the case where the projection is formed on the upper surface of the lower insulating member.

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 (12)

Electrode assembly; A can containing the electrode assembly and the electrolyte; A lower insulating member positioned between the electrode assembly and the bottom surface of the can; And a cap assembly coupled to the open top of the can, Secondary battery, characterized in that the irregularities formed on the upper surface of the lower insulating member. The method of claim 1, Secondary battery, characterized in that the lower surface of the lower insulating member is flat. The method of claim 1, The secondary battery of claim 1, wherein the convex portion of the concave-convex portion is located in an area other than an edge of the lower insulating member. The method of claim 1, A secondary battery, characterized in that a plurality of holes are formed in the lower insulating member. The method of claim 4, wherein The hole is a secondary battery, characterized in that formed in the portion of the concave-convex portion is not formed. The method according to any one of claims 1 to 5, The outer shape of the can is a cylindrical, the secondary insulating member is characterized in that the disk-shaped. Electrode assembly; A can containing the electrode assembly and the electrolyte; A lower insulating member positioned between the electrode assembly and the bottom surface of the can; And a cap assembly coupled to the open top of the can, Secondary battery, characterized in that a plurality of protrusions formed on the upper surface of the lower insulating member. The method of claim 7, wherein Secondary battery, characterized in that the lower surface of the lower insulating member is flat. The method of claim 7, wherein The secondary battery is characterized in that the projection is located in an area other than the edge of the lower insulating member. The method of claim 7, wherein A secondary battery, characterized in that a plurality of holes are formed in the lower insulating member. The method of claim 10, The hole is a secondary battery, characterized in that formed in the portion where the protrusion is not formed. The method according to any one of claims 7 to 11, The outer shape of the can is a cylindrical, the secondary insulating member is characterized in that the disk-shaped.

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