KR20040058922A - Prismatic type lithium secondary battery - Google Patents

Abstract

PURPOSE: A prismatic lithium secondary battery is provided, to prevent the shrinkage of a separator due to abnormal high temperature and to prevent the shortage of the electrode plates having different polarities, thereby improving the safety of a battery. CONSTITUTION: The prismatic lithium secondary battery comprises a battery part(22) which comprises a positive electrode plate, a negative electrode plate and a separator placed between the positive electrode plate and the negative electrode plate; a can which provides the space receiving the battery part; a cap assembly which is combined to the upper part of the can, and comprises a cap plate having an electrolyte solution input hole(31b) and an electrode terminal set through the terminal hole formed in the cap plate and having a gasket for the insulation with the cap plate; and an electrical insulation case(30) which is set on the battery part and has a space part receiving the upper outer face of the battery part. Preferably the electrical insulation case(30) comprises a plated body(31) part which has a lead hole(31a) drawing any one electrode lead(27) drawn from the electrode plate, and a bridge part(33) which is extended downward from the bottom edge of the body part and has a space part where the upper outer face of the battery part can be inserted.

Description

Square type lithium secondary battery {Prismatic type lithium secondary battery}

The present invention relates to a rectangular lithium secondary battery, and more particularly, to a rectangular lithium secondary battery having an improved structure of an insulating case which mutually insulates a cap assembly and a battery unit.

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, and a camcorder. In particular, the lithium secondary battery has an operating voltage of 3.6 V or more, 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 devices, and is rapidly expanded in terms of high energy density per unit weight. There is a trend.

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.

Moreover, although a lithium secondary battery is manufactured in various shapes, a typical shape is cylindrical shape, square shape, and pouch type.

Referring to FIG. 1, the conventional rectangular lithium secondary battery 10 includes a can 11, a battery unit 12 accommodated in the can 11, and a cap assembly coupled to the can 11. 100).

The can 11 is a rectangular case made of metal. In the battery unit 12, the positive electrode plate 13, the separator 14, and the negative electrode plate 15 are wound in a jelly-roll type, and are inserted into the can 11. The positive and negative lead 16 and 17 are drawn out from the positive and negative plates 13 and 14, respectively.

The cap assembly 100 includes a cap plate 110 coupled to an upper end of the can 11, an electrode terminal 130 inserted into the cap plate 110 via a gasket 120, and the cap. Insulation plate 140 is provided on the lower surface of the plate 110, and the terminal plate 150 is provided on the lower surface of the insulating plate 140 and electrically connected to the electrode terminal 130.

The cap plate 140 is formed with an electrolyte injection hole 111 that provides a passage through which the electrolyte is injected into the can 11, and the ball 160 is coupled to the electrolyte injection hole 111 so as to be hermetically sealed. have.

In this case, the positive lead 16 is connected to the bottom surface of the cap plate 110, and the negative lead 17 is connected to the electrode terminal 130 through the terminal plate 150.

On the other hand, the can 11 is located in the upper portion of the battery unit 12, an insulating case 190 for insulating the battery unit 12 and the cap assembly 100 is provided. The insulation case 190 has a lead hole 191 through which the electrode lead 17 is drawn out, and an electrolyte inlet hole 192 that provides a path through which the electrolyte flows.

In the rectangular lithium secondary battery 10 having the structure described above, the jelly-roll battery part 12 is inserted into the can 11, and the insulating case 190 is seated on the top surface of the battery part 12. Let's do it. The positive lead 16 and the negative lead 17 drawn from the battery unit 12 are welded to the bottom surface of the cap plate 110 and the electrode terminal 130, respectively.

Next, the cap assembly 100 is welded to the can 11, and the electrolyte is injected through the electrolyte injection hole 111. The electrolyte injection hole 111 is sealed as the ball 160.

However, the conventional rectangular lithium secondary battery 10 has the following problems.

The separator 14 is interposed to insulate the positive electrode plate 13 and the negative electrode plate 15, and is vulnerable at a high temperature of about 120 ° C. or higher. Therefore, when the internal temperature rises to 120 ° C. or more due to the abnormality of the battery 10, the separator 14 is thermally deformed to cause shrinkage. This shrinkage phenomenon leads to electrical short-circuits between the positive electrode plate 13 and the negative electrode plate 15 with different polarities, which may be fatal to the safety of the battery 10.

The present invention is to solve the above problems, the structure is improved so that the insulating case interposed between the can and the cap assembly to protect the battery unit to provide a rectangular lithium secondary battery that improves the safety of the battery. have.

1 is a partial cross-sectional view showing a conventional rectangular lithium secondary battery,

2 is an exploded perspective view illustrating a rectangular lithium secondary battery according to an embodiment of the present invention;

3 is an exploded perspective view illustrating the insulating case and the battery unit of FIG. 2;

4 is a perspective view illustrating a state in which a battery unit is coupled to the insulating case of FIG. 3;

FIG. 5 is a cross-sectional view partially showing the rectangular lithium secondary battery of FIG. 2; FIG.

<Brief description of symbols for the main parts of the drawings>

20 ... Lithium rechargeable battery 21 ... can

22 Battery ... 23 Anode plate

24.Separator 25 ... cathode plate

26 ... anode lead 27 ... anode lead

30.Insulation case 31.Main unit

31a ... Lead hole 31b ... Electrolyte inlet hole

32.Wall 33.Bridge

200 ... cap assembly 210 ... cap plate

220 ... gasket 230 ... electrode terminal

240 ... insulation plate 250 ... terminal plate

In order to achieve the above object, a rectangular lithium secondary battery according to an aspect of the present invention,

A battery unit in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are disposed;

A can providing a space in which the battery unit is accommodated;

A cap assembly coupled to an upper portion of the can and having a cap plate having an electrolyte injection hole formed therein, and an electrode terminal having a gasket interposed therebetween for insulating the cap plate on an outer surface thereof through a terminal through hole formed in the cap plate; And

And an insulating case installed on the battery unit and having a space part configured to receive an outer surface of the upper end of the battery unit.

In addition, the insulating case may include a flat body portion having a lead hole through which one of the electrode leads drawn out from the electrode plate is formed, and a space portion extending from the bottom edge of the bottom portion of the body portion downward to a space formed therein. It characterized in that it comprises a; bridging portion is inserted into the outer surface of the upper end.

In addition, the bridge portion is interposed between the can and the outer surface of the upper end of the battery portion to set the position of the battery portion relative to the can.

Furthermore, it is characterized in that it is formed integrally from the main body portion.

In addition, the insulating case is characterized in that made of a polymer material having a higher melting point temperature than the separator.

In addition, the upper surface of the main body portion is characterized in that the wall portion of a predetermined height is further formed so that the electrode lead drawn upward from the battery portion through the lead hole does not contact the inner wall of the can.

Hereinafter, a rectangular lithium secondary battery according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 illustrates a rectangular lithium secondary battery 20 according to an embodiment of the present invention.

Referring to the drawings, the prismatic lithium secondary battery 20 may include a can 21, a battery unit 22 accommodated in the can 21, and a cap assembly coupled to an upper portion of the can 21. 200).

The can 21 is a rectangular metal material in which a hollow is formed. The can 21 itself may serve as a terminal.

The battery unit 22 includes a positive electrode plate 23, a negative electrode plate 25, and a separator 24. The positive and negative plates 23 and 25 and the separator 24 each consist of one strip. The battery unit 22 is arranged in the order of the positive electrode plate 23, the separator 24, the negative electrode plate 25, and the separator 24, and is wound in a jelly-roll shape.

The positive electrode plate 23 includes a positive electrode current collector made of a thin metal plate, for example, aluminum foil having excellent conductivity, and a positive electrode active material layer coated mainly on lithium-based oxides coated on both surfaces thereof. The positive electrode lead 23 is electrically connected to a region of the positive electrode current collector in which the positive electrode active material layer is not formed. An end of the positive electrode lead 26 is drawn out over the upper end of the battery unit 22.

The negative electrode plate 25 includes a negative electrode current collector made of a conductive metal plate, such as a copper foil, and a negative electrode active material layer coated mainly on a carbon material coated on both surfaces thereof. The negative electrode lead 27 is connected to the area | region of the negative electrode collector in which the negative electrode active material layer was not formed also from the said negative electrode plate 25. As shown in FIG. An end of the negative electrode lead 27 is also drawn out over the upper end of the battery unit 22.

In this case, the positive electrode and negative electrode leads 26 and 27 may be disposed with different polarities, and the positive electrode plate 23 (the positive and negative electrode leads 26 and 27 may be drawn out from the battery unit 22. Insulating tape 28 is wound to prevent short circuit between the terminals.

The separator 24 is made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. The separator 24 may be formed to be wider than the positive electrode plate 23 and the negative electrode plate 25 to prevent short circuits between the electrode plates 23 and 25.

The cap assembly 200 is provided with a flat cap plate 210 having a size and shape corresponding to the inlet of the can 21. A terminal through-hole 211 is formed in the center of the cap plate 210. An electrolyte injection hole 212 is formed at one side of the cap plate 21.

The electrode terminal 230 may be inserted into the terminal through hole 211. The outer surface of the electrode terminal 230 is provided with a tube-shaped gasket 220 to insulate it from the cap plate 210. An insulating plate 240 is installed on the lower surface of the cap plate 210. The terminal plate 250 is installed on the bottom surface of the insulating plate 240.

The electrode terminal 230 is inserted through the terminal through hole 211 in a state in which the gasket 220 surrounds the outer circumferential surface. The bottom portion of the electrode terminal 230 is electrically connected to the terminal plate 250 with the insulating plate 240 interposed therebetween.

According to a feature of the invention, the upper surface of the battery unit 22 for electrical insulation between the battery unit 22 and the cap assembly 200, and at the same time to cover the upper end of the battery unit 22 An insulating case 30 is provided. The insulating case 30 is a polymer resin having insulating properties, and preferably made of polypropylene.

This will be described in more detail as follows.

3 illustrates the battery unit 22 and the insulating case 30 of FIG. 2 separated from each other, and FIG. 4 illustrates a state in which the battery unit 22 is coupled to the insulating case 30 of FIG. 3.

Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

3 and 4, the insulating case 30 has a size and shape that can be inserted into the can 21. The insulating case 30 includes a main body portion 31, a wall portion 32 extending upward from the main body portion 31, and a bridge portion 33 extending downward from the main body portion 31. .

The main body 31 has a rectangular parallelepiped shape, and a lead hole 31a through which the negative electrode lead 27 can be drawn out is formed in the center thereof. One side of the main body 31 is formed with an electrolyte inlet hole 31b that provides a path for the electrolyte to flow into the battery unit 22.

The wall portion 32 is formed at the edge of the upper surface of the main body portion 31. The short side wall part 32a which extends predetermined height upward from the edge of the short side part of the said main-body part 31 is formed. The short side wall portion 32a extends from the short side portion to an appropriate region of the long side portion adjacent thereto.

Further, long side wall portions 32b extending upwards by a predetermined height are formed on both edges of the long side portions of the main body portion 31. The long side wall portion 32b is located at the edge of the long side portion corresponding to the portion where the lead hole 31a is located. The long side wall portion 32b blocks the negative lead 27 drawn out through the lead hole 31a from contacting the inner wall of the can 21 having different polarities when bending in an S-shape in order to reduce the space of the battery. Play a role. This barrier wall portion 32b is flush with the short side wall portion 32a.

The bridge portion 33 extends to the bottom edge of the main body portion 31. The bridge portion 33 extends a predetermined length downward from an edge of the bottom surface of the main body portion 31.

The short side bridge part 33a is formed from the edge of the short side part of the bottom face of the said main body part 31. As shown in FIG. It is preferable that the said short side bridge part 33a is formed in the short side part of the main body part 31 which opposes.

Moreover, the long side bridge part 33b is formed from the long side edge of the bottom face of the said main body part 31. As shown in FIG. The long side bridge portion 33b is formed in the long side portion of the main body portion 31 facing each other, and is integrally connected to the short side bridge portion 33a.

Accordingly, the bridge portion 33 has a rectangular frame shape, and a space portion exists therein. In addition, it will be said that the short side and long side bridge portions 33a and 33b are integrally formed with the main body portion 31 and advantageous in injection.

Alternatively, only one of the short side or long side bridge portions 33a and 33b may extend from the main body portion 31, and the main body portion 31 may be formed using the bridge portion 33 provided separately. Various embodiments, such as may be mounted on the bottom.

When such a bridge portion 33 is formed on the bottom surface of the main body portion 31, the bridge portion 33 spaces downward from the bottom surface of the main body portion 31 by a length extending from the edge of the main body portion 31. Wealth will occur.

At this time, the upper end side of the battery unit 22 can be inserted into the space portion. That is, the battery unit 22 is wound in the state arranged in the order of the positive electrode plate 23, the separator 24, the negative electrode plate 25 as described above, the outermost surface to the finish tape 300 for fixing them Is attached.

The upper end of the battery part 22 through which the positive and negative electrode leads 26 and 27 electrically connected to the positive and negative electrode plates 23 and 25 are drawn out is lowered from the main body part 31 by the bridge part 33. It is inserted into the space part which exists in a direction, and sets the position. To this end, the bridge portion 33 extending below the main body portion 31 should be formed to have a length that can surround the outer surface of the upper end of the battery unit 22 as a whole.

In addition, since the bridge part 33 is formed to prevent thermal deformation of the battery part 22 due to shrinkage of the separator 24, a polymer material having a higher melting temperature than the separator 24, for example, 120 ° C. or more. It is preferably made of a polypropylene material that can withstand.

And, the thickness of the bridge portion 33 is preferably within 0.01 to 1 millimeter. When the thickness of the bridge portion 33 is 0.01 mm or less, the thickness of the bridge portion 33 is so thin that the formability is not good. On the other hand, when the thickness of the bridge portion 33 is 1 millimeter or more, the capacity of the battery unit 22 is relatively reduced as the space occupied in the can 21 increases.

Looking at the assembly process of the rectangular lithium secondary battery 20 having the structure as described above is as shown in FIG.

First, the battery unit 22 disposed in the order of the positive electrode plate 23, the separator 24, the negative electrode plate 25, and the separator 24 is wound in a jelly-roll shape. The wound battery part 22 is inserted into the square can 21.

An insulating case 30 is mounted on the battery unit 22. The negative electrode lead 27 is drawn out through the lead hole 31a formed in the main body portion 31 of the insulating case 30. The positive lead 26 is drawable between the outer wall of the insulating case 30 and the inner wall of the can 21.

At this time, due to the formation of the bridge portion 33 extending downward from the bottom surface of the main body portion 31 along the edge thereof, the upper end portion of the battery unit 22 in the space existing inside the insulating case 30. The outer surface is inserted.

The size of the space existing in the downward direction of the bottom of the main body 31 due to the bridge portion 33 is a size that can wrap the entire outer surface of the upper end of the battery unit 22. The upper end face of the battery part 22 is located on the bottom face of the main body part 31, and the side surface of the battery part 22 is in contact with the inner surface of the bridge part 33.

In addition, the bridge portion 33 is interposed between the inner wall of the can 21 and the outer surface of the upper end of the battery portion 22 to set the position of the insulating case 30 with respect to the can 21.

Next, the cap assembly 200 is supplied to the upper end of the can 21. The cap assembly 200 has the electrode terminal 230 interposed on the outer circumferential surface of the gasket 220 is inserted into the cap plate 210 through the terminal through-hole 211, the insulating plate 240 on the bottom surface of the cap plate 210 The terminal plate 250 is electrically connected to each other through.

The anode lead 26 is directly welded to the bottom surface of the cap plate 210, and the cathode lead 27 drawn out through the lead hole 31a is welded to the electrode terminal 230.

At this time, the negative electrode lead 27 is folded to the left and right several times due to the limited internal space of the can 21 is connected to the electrode terminal 230, the folded portion of the body portion 32 that is opposed to the lead hole (31a) Since it is located in the space between the long side wall portion 32b, the inner wall of the can 21 can be insulated.

Subsequently, a boundary portion that meets the cap plate 210 is welded to the can 21. Accordingly, it serves as a positive terminal of the can 21. Next, the electrolyte is injected through the electrolyte injection hole 212 formed in the cap plate 210, and the electrolyte injection hole 212 is sealed using the ball 260.

As described above, in the rectangular lithium secondary battery of the present invention, the outer surface of the upper end of the battery unit is located in the space portion generated by the bridge portion provided under the insulating case installed for insulation of the cap assembly and the battery unit. In addition, the shrinkage phenomenon of the separator due to the high temperature can be prevented in advance. Thereby, the short circuit of the pole plate which differs in polarity can be interrupted, and the safety of a battery can be improved.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (9)

A battery unit in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are disposed; A can providing a space in which the battery unit is accommodated; A cap assembly coupled to an upper portion of the can and having a cap plate having an electrolyte injection hole formed therein, and an electrode terminal having a gasket interposed therebetween for insulating the cap plate on an outer surface thereof through a terminal through hole formed in the cap plate; And And an insulating case provided on the battery unit and having a space part accommodating an outer surface of the upper end of the battery unit. The method of claim 1, The insulating case may include a flat body portion having a lead hole through which one of the electrode leads drawn out from the electrode plate is formed, and an outer surface of the upper end of the battery portion extending in a downward direction from a bottom edge of the bottom portion of the body portion. The insertable bridge portion; rectangular lithium secondary battery comprising a. The method of claim 2, The bridge part is a rectangular lithium secondary battery, characterized in that extending from the edge of the short side and the long side of the bottom of the main body portion to cover the upper end of the battery unit. The method of claim 2, And the bridge portion is interposed between the can and an outer surface of the upper end of the battery portion to set the position of the battery portion with respect to the can. The method of claim 2, The bridge portion is a rectangular lithium secondary battery, characterized in that formed integrally from the body portion. The method of claim 2, The insulating case is a rectangular lithium secondary battery, characterized in that made of a polymer material having a higher melting point temperature than the separator. The method of claim 6, The insulating case is a rectangular lithium secondary battery, characterized in that the polypropylene. The method of claim 2, The thickness of the bridge portion is a rectangular lithium secondary battery, characterized in that about 0.01 to 1 millimeter. The method of claim 2, The upper surface of the body portion is a rectangular lithium secondary battery, characterized in that the wall portion of a predetermined height is further formed so that the electrode lead drawn upward from the battery portion through the lead hole does not contact the inner wall of the can.