KR100571234B1 - Secondary Battery - Google Patents

Abstract

In a secondary battery comprising a safety device and a bare cell including a container-type can, an electrode assembly embedded in the can through an opening of the can, and a cap assembly closing the opening of the can, a secondary battery safety such as a protective circuit board is provided. The device is fixed with a molding resin or a resin part and is included in the battery part, and at least a part of the lower periphery of the battery part is provided with a metal skirt that can embrace the upper part of the bare cell, and the bare cell and the battery part Disclosed is a secondary battery characterized in that the coupling is made by coupling the metal skirt portion and the bare cell.

According to the present invention, the safety circuits such as the protection circuit board and the bimetal may be coupled to the bare cell with high mechanical strength to prevent the safety devices from being easily detached from the bare cell by bending or twisting by external force.

Description

Secondary Battery

1 is a schematic exploded perspective view of an example of a conventional lithium ion resin pack battery in a stage before being bonded by a molding resin;

2 is a perspective view showing a conventional lithium ion resin pack secondary battery in a state bonded by a molding resin;

Figure 3 is an exploded front cross-sectional view for showing the coupling relationship between the bare cell and each element of the battery component part in one embodiment of the present invention;

4 and 5 are front cross-sectional views showing a coupling state between the bare cell and the battery component part in the embodiments according to the present invention;

6 is an exemplary front sectional view of a metal skirt that may be used in the embodiment of FIG.

* Explanation of symbols for the main parts of the drawings

20: molded resin portion 30,210: protective circuit board

31,32,212,312: External terminals 36,37,214,314: Connection terminals

41,42,246: Connection lead 100: Bare cell

110: cap plate 120: insulator gasket

130: negative electrode terminal 200: battery part

240: molded resin case 246: sleeve

212,312: external terminal 220: molded resin accessory

222,242: hole 230,330: metal skirt

231: lower skirt 333: through hole

The present invention relates to a secondary battery, and more particularly, to a bare cell including an electrode assembly, a can, and a cap assembly, and a secondary battery formed by electrically connecting a protective circuit board to the bare cell.

Secondary batteries have been researched and developed in recent years due to the possibility of recharging and miniaturization and large capacity. Representative examples of the recent development and use include nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium-ion (Li-ion) batteries.

In these secondary batteries, most of the bare cells are formed by storing an electrode assembly consisting of a positive electrode, a negative electrode, and a separator, usually in a can made of aluminum or an aluminum alloy, closing the can with a cap assembly, and then injecting and sealing an electrolyte into the can. do. The can may be formed of iron, but if it is formed of aluminum or an aluminum alloy, the light may be lightened by the light property of aluminum, and may not be corroded even when used for a long time under high voltage.

However, batteries have the potential to emit a lot of energy as an energy source. In the case of a secondary battery, energy is stored in itself in a state where it is charged, and in the process of charging, energy is accumulated from other energy sources. When an abnormality of a secondary battery such as an internal short circuit occurs in such a process or state, energy stored in the battery is released in a short time, which may cause safety problems such as ignition and explosion.

Recently used lithium-based secondary battery has a high activity of the lithium itself because of the high risk of fire or explosion when a battery failure occurs. In the case of a lithium ion battery, only lithium in an ionic state exists, not lithium in a metal state, and thus safety is improved compared to a battery using metal lithium. However, materials such as negative electrodes and non-aqueous electrolytes, which are still used in batteries, have a high risk of ignition or explosion when battery abnormalities occur due to flammability.

Accordingly, the secondary battery is equipped with various safety devices to prevent fire or explosion due to an abnormality of the battery itself in the charged state or during the charging process. Safety devices are connected to the positive and negative terminals of the bare cell by a conductor structure, commonly referred to as a lead plate. These safety devices cut off the current when the battery voltage rises rapidly due to a high temperature rise of the battery, excessive charge or discharge, or the like, thereby preventing the battery from rupturing or igniting. The safety devices connected to the bare cell include a protection circuit that senses an abnormal current or voltage and prevents current flow, a positive temperature coefficient (PTC) element operating by overheating due to the abnormal current, and a bimetal.

The secondary battery in a state in which the bare cell and the safety device are combined is stored in a separate case to form a secondary battery having a completed appearance. However, it is common for secondary batteries to vary in composition, form, size, etc., of elements used in manufacturing, by product model for each manufacturer, and the design of an appropriate safety device also varies according to these various factors. In general, manufacturers of secondary batteries form a secondary battery by combining a bare cell and a protection circuit into an integrated package. Secondary batteries are often determined in material and design to form part of the product set on which the secondary batteries are mounted.

In this situation, the secondary battery is not compatible with the product, and it is difficult for the consumer to arbitrarily select the secondary battery to be used in the product set. Even if the battery's operating conditions and functions were the same, no secondary battery could be used other than the exclusively designed product for the product set.

In order to solve this problem, secondary batteries are manufactured to be mounted inside the casing of various product sets when the operation conditions and functions of the batteries are the same as the primary batteries. In this case, the secondary battery is made of a resin pack secondary battery in which a bare cell and a safety terminal such as a protective circuit board are first connected by welding, and a space therebetween is filled with a molding resin to physically couple the bare cell and the protective circuit. There are many. In the case of the resin pack secondary battery, the appearance can be smoothed by molding or the thickness corresponding to the case can be reduced compared to the case where a core pack having safety devices attached to a bare cell is completed in a case. There is no advantage.

1 is a schematic exploded perspective view of an example of a conventional lithium ion resin pack battery that is in a step prior to being bonded by molding resin, and FIG. 2 is a view of a conventional lithium ion resin pack secondary battery bonded by molding resin. It is a perspective view showing.

1 and 2, the protection circuit board 30 is disposed side by side on a surface where the electrode terminals 130 and 111 of the bare cell are formed in the pack battery. As shown in FIG. 2, the gap between the bare cell 100 and the protection circuit board is filled with a molding resin. When filled with the molding resin, the molding resin may cover the outer surface of the protective circuit board, but the external input / output terminals 31 and 32 of the battery are exposed to the outside.

The bare cell 100 is provided with a positive terminal 111 and a negative terminal 130 on side surfaces facing the protective circuit board 30. The positive terminal 111 may be a cap plate made of aluminum or an aluminum alloy or a nickel-containing metal plate bonded on the cap plate. The negative electrode terminal 130 is a terminal protruding in the shape of a protrusion on the cap plate, and is electrically isolated from the cap plate 110 by an insulator gasket interposed therebetween.

The protection circuit board 30 is formed by a circuit formed on a panel made of resin, and external input / output terminals 31 and 32 are formed on an outer surface thereof. The substrate 30 has substantially the same size and shape as the opposite surface (cap plate surface) of the bare cell 100.

The circuit part 35 and the connection terminals 36 and 37 are provided on the rear surface of the protective circuit board 30 on which the external input / output terminals 31 and 32 are formed, that is, the inner surface. The circuit part 35 is provided with the protection circuit etc. for protecting a battery from overcharge and overdischarge at the time of charge / discharge. The circuit portion 35 and the respective external input / output terminals 31 and 32 are electrically connected by a conductive structure passing through the protective circuit board 30.

Connection leads 41 and 42, an insulating plate 43, and the like are disposed between the bare cell 10 and the protection circuit board 30. The connection leads 41 and 42 are usually made of nickel and are formed for electrical connection with the connection terminals 36 and 37 of the cap plate 110 and the protection circuit board 30, and have a 'L' shape or a planar structure. . Resistance spot welding may be used for the connection of the connection leads 41 and 42 to the respective terminals 36 and 37. In this example, a breaker or the like is separately formed in the connection lead 42 between the protective circuit board and the negative electrode terminal. In this case, the breaker is excluded from the circuit portion 35 of the protective circuit board. The insulating plate 43 is provided to insulate between the connection lead 42 connected to the negative electrode terminal 130 and the cap plate serving as the positive electrode.

However, when the bare cell 100, the protection circuit board 30, and other battery parts are formed into a pack battery using molding resin, as shown above, the battery parts such as the protection circuit board 30 may be removed in the pack battery state. The molded resin part 20 fixedly coupled to the bare cell 100 has a material different from that of the bare cell 100 made of metal such as the cap plate 110 or the can, and the adhesion area is weak because the contact area is not large. there is a problem.

To increase the bond strength, increase the connection structure of the lead plate or the like, or weld a separate reinforcement structure to the cap plate, and partially form a space between the reinforcement structure and the bare cell so that the molding resin fills this space and reinforces the structure. You can think of ways to wrap it around. If the lead plate or reinforcing structure is large, it is located deep in the mold to increase the adhesion between the mold including the safety device and the bare cell.

But. Since the molded resin mold must cover the reinforcing structure, this type of reinforcing structure has a limitation in expanding because the size of the battery must be limited. In addition, when the protrusion of the reinforcing structure is large, the mold end is far from the cap plate contact surface of the mold and the bare cell, so that when the lateral force acts on the mold end, the bending external force acting on the contact surface is likely to be large. The heterogeneity of the molding resin and the material of the metal reinforcing structure also makes it difficult to increase the adhesive strength.

In addition, in order to pour the molding resin between the bare cell and the protective circuit board, and to harden, it is cumbersome because the mold must be used and the mold must be peeled off after use. When pouring the resin, the resin may not be evenly filled between the protection circuit board and the bare cell, and in particular, if the reinforcing structure is complicated, it is more difficult to evenly fill the molding resin between the protection circuit and the bare cell.

The present invention is to solve the above problems of the conventional pack-type secondary battery, and an object of the present invention is to provide a secondary battery having a configuration capable of stably coupling safety devices such as a bare cell and a protection circuit board with high strength.

The present invention is a configuration that does not cause a problem that the cumbersome work of the molding resin and the molding resin is not well filled between the protective circuit board and the bare cell in the conventional pack-type secondary battery, the adhesion between the protective circuit board and the bare cell is weakened. It is an object to provide a secondary battery having a.

The present invention for achieving the above object, a bare cell comprising an electrode assembly including a cathode, a separator, a positive electrode, a container-type can for receiving the electrode assembly and the electrolyte, and a cap assembly for closing and sealing the opening of the can and; A battery part including a safety device electrically coupled with the bare cell, and a metal skirt positioned below and coupled to the bare cell while receiving at least a portion of an upper portion of the bare cell; It is characterized by comprising.
The battery part of the present invention may include a molded resin part or a molded resin mold so that the safety device in the battery part part may be fixed by such a molded resin part or a molded resin mold.

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In the present invention, the safety device is typically formed by combining a protective circuit board with a bimetal or protective circuit board and a PTC (positive thermal coefficient) element. Hereinafter, even when only the protection circuit board is specified, the protection circuit board may be used as a concept including a thermal blocking device.

In the present invention, the coupling between the metal skirt and the bare cell may be made by welding, and the welding may be made by laser welding because the material of the can is usually a good conductor such as aluminum or an aluminum containing metal.

In the present invention, the battery part including the safety device may be prepared in advance so that the electrical connection lead is exposed to the bottom surface of the battery part in a state of being connected with a connection terminal such as a protective circuit board in the molding step for electrical connection with the bare cell. have.

In the present invention, the metal skirt portion can be used as a connecting means for electrical connection with the bare cell of the battery component portion. For example, if the positive connection terminal of the battery component part is connected to the metal skirt part of the battery part part directly or through a separate connection lead, the metal skirt part is electrically connected through welding with the can, and thus the can wall and the battery part part, which are the anodes of the bare cell, are connected. Electrical connection of the positive connection terminal is made.

In the present invention, the battery part including the safety device may expose one connection terminal of the safety device such as a protective circuit board to form a molding resin for electrical connection with a bare cell negative electrode. For example, a groove is formed in the lower center of the mold to expose the negative connection terminal of the protection circuit board, and when the battery part is fixed to the cap plate, the negative terminal of the protruding bare cell is introduced into the groove to connect the negative connection of the protection circuit board. It can be connected to the terminal.

In the present invention, when the thickness of the metal skirt is a normal level, for example, 0.2mm or more, the resistance to bending or twisting external force given to the battery from the outside is low among the bonding force of the metal skirt and battery parts, the bonding force of the metal skirt and cans Will be determined by By the way, in the present invention, the battery part may be coupled with the metal skirt over a substantial portion of the periphery. And, the metal skirt can be combined with the can of the bare cell over a substantial portion. That is, the coupling between the metal skirt and the battery component portion, the metal skirt and the can becomes a considerable strength, and the connection lead protruding from the conventional resin pack secondary battery is significantly larger than that between the safety device and the bare cell compared to the form in which the resin lead is inserted into the resin mold. It can be said that the mechanical bond strength is very strengthened.

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

Figure 3 is an exploded front cross-sectional view for showing the coupling relationship between the bare cell and each of the battery component parts in one embodiment of the present invention.

4 and 5 are front cross-sectional views showing the coupling state between the bare cell and the battery component part in the embodiments according to the present invention.

Referring to FIG. 3, the battery component part 200 may include a protective circuit board 210, a molded resin accessory 220 attached to a lower portion of the protective circuit board, and a sleeve 246 formed on an upper portion of the protective circuit board. It consists of a molded resin case 240 corresponding to the molded resin portion of the present invention for accommodating the furnace protection circuit board 210 and the molded resin accessory 220, and a metal skirt 230 made of upper and lower skirts. The upper skirt is positioned between the sleeve 246 of the molded resin case 240 and the molded resin accessory 220, and the lower skirt 231 extends under the battery part 200 to cover the top of the bare cell 100. It is made to wrap.

The upper skirt is formed to have a thickness greater than or equal to the molded resin part 220 of the battery part 200, and is located deep between the molded resin case 240 sleeve 246 and the molded resin part 220, so that an external force applied to the battery itself. It can resist bending and twisting. However, an adhesive is usually used to secure the bonding in the process of assembling the upper skirt to the battery component part 200.

Holes 222 are formed in the central portion of the molded resin accessory 220, and the negative electrode is installed in the center of the bottom surface of the protective circuit board 210 in the state of a battery component in which the protective circuit board 210 and the molded resin accessory 220 are combined. The connection terminal 214 may be exposed. The positive connection terminal of the protection circuit board has a connection lead 246 protruding downward from the periphery of the protection circuit board 210. The connection lead 246 is provided so as to be exposed to the outer periphery of the molded resin accessory 220 article in the engaged state with the molded resin accessory 220.

The molded resin case 240 has a hole 242 formed at a position of the external terminal 212 of the protective circuit board 210, and the external terminal is formed through the hole 242 in the state of a battery component coupled with the protective circuit board 210. 212 is made to be exposed to the outside. The sleeve 246 formed at the periphery of the resin case 240 is formed to receive and surround the protective circuit board 210 and the resin accessory 220. An upper skirt portion of the metal skirt 230 is adhesively fixed between the resin accessory 220 outer side and the sleeve 246 inner side.

Referring to FIGS. 3 and 4, the bare cell 100 is coupled with the battery component part including the metal skirt 230. A portion of the negative terminal 130 protruding from the cap assembly of the bare cell passes through the hole 222 in the resin accessory 220 of the battery component part and is connected to the negative electrode connecting terminal 214 at the center of the bottom surface of the protective circuit board 210. . The connection lead 246 included in the positive electrode connection terminal of the protective circuit board is positioned between the resin accessory 220 and the resin case sleeve 246 in the battery component part, and also between the resin accessory 220 and the resin case sleeve 246. It is electrically connected with the top of the metal skirt 230 located in the.

One way of forming this type of battery component is to first combine the protective circuit board 210 and the lower resin component 220 and insert the combined portion above the metal skirt 230. Concave grooves 235 are formed in the metal skirt 230, and protrusions 225 are formed in the resin accessory 220, so that the metal skirt 230 may be mechanically coupled to the adhesive. At this time, since the connection lead 246 and the metal skirt 230 of the positive electrode connection terminal overlap, the external contact resistance can be eliminated by welding them together from the outside. The welding uses a laser welding method to prevent the resin parts 220 from melting together and deforming.

An adhesive is applied to the outside of the upper portion of the metal skirt 230 or the inside of the resin case sleeve 246, and the upper portion of the metal skirt 230 is inserted into the sleeve 246 to be combined. Thereafter, the battery component is coupled to the bare cell 100. In addition to the adhesive, the groove 234 and the projection 244 may be used to increase the coupling force between the sleeve 246 and the upper skirt.

The lower skirt 231 of the metal skirt 230 receives and covers the top of the bare cell 100. In this state, in order to increase the bonding strength between the battery part and the bare cell, the can of the lower skirt 231 and the cell 100 may be joined by welding or adhesive method.

In the present embodiment, since the metal skirt 230 is deeply coupled over the entire periphery of the battery component part, the metal skirt 230 maintains a strong mechanical bond strength in the battery component part even though the bonding method is not performed by welding or the like. In addition, the lower skirt 231 of the metal skirt can also be combined while surrounding the bare cell and the entire periphery, and since the can of the bare cell is metal, the combination of the metal skirt 230 and the can can be welded between the metal and the metal. Sufficient mechanical strength can be achieved. In this embodiment, when the thickness of the metal skirt 230 is the level of a typical can, for example, 0.2 mm or more, the bonding force of the metal skirt 230 and the battery part, the bonding force of the metal skirt and the can, and the strength of the metal skirt itself. Is sufficiently high, and the resistance against bending or twisting external force given to the battery from the outside becomes sufficiently high as compared with a connection lead protrudingly inserted between resins in the conventional resin pack secondary battery.

Referring to Fig. 5, the battery part 300 is molded by the molding resin molding method. The molding resin molding is formed in a form that can be combined with the bare cell 100 in a state in which a protective circuit board, a connection lead (not shown), a metal skirt 330, and the like of the connection terminal, which are not separately illustrated, are coupled. For example, a groove corresponding to the center hole 222 of the resin accessory 220 of FIG. 4 is formed in the center of the bottom surface of the mold to expose the negative electrode connection terminal 314 of the protective circuit board.

The molding resin molding may be performed while the connecting lead (not shown) of the anode connecting terminal is welded to the metal skirt 330 at the periphery thereof, and the mold is formed so that the connecting lead penetrates through the mold to contact the cap plate 110 of the bare cell. Molded resin molding may be made to expose the bottom surface. In order to increase the bonding force between the metal skirt 330 and the mold, the upper portion of the metal skirt 330 may form a through hole 333 as shown in FIG. In this case, the resin is connected to the inside of the metal skirt 330 through the through hole. Although the metal and the resin mold are heterogeneous materials, the resin portion connecting the inside and the outside of the skirt 330 through the through hole 333 may prevent the upper portion of the metal skirt 330 from the resin mold.

In the above embodiments, in order to strengthen the electrical connection between the negative electrode terminal 130 of the bare cell and the negative electrode connection terminal 214 of the protective circuit board 210, the negative electrode connection terminal may have a plate spring shape. In addition, in order to reduce the contact resistance, the electrical terminal of the battery part coupled to the bare cell electrode and the electrode contact surface of the bare cell may be plated with gold, which is a good conductor, or a good conductor such as silver paste may be applied.

In the present invention, the central hole of the molded resin component coupled to the protruding cathode of the bare cell forms a neck at the bottom inlet, and the jaw and the neck are mechanically coupled to the jaw at the end of the cathode so that the mechanical part of the bare cell and the battery part are mechanically coupled. It can increase the stability of the coupling or electrical contact.

According to the present invention, safety devices such as a protective circuit board and a bimetal can be coupled to a bare cell with high mechanical strength. That is, it is possible to prevent the safety devices from being easily released from the bare cell by bending or twisting by external force.

According to the present invention, the problem of protecting the periphery of the safety valve and evenly filling of the resin can be fundamentally eliminated while molding the molding resin in the conventional resin pack secondary battery.

Claims (8)

An electrode assembly comprising a cathode, a separator, and an anode; A container-type can containing the electrode assembly and the electrolyte; A bare cell comprising a cap assembly for closing and sealing an opening of the can; A safety device electrically coupled with the bare cell; A battery component part disposed below and including a metal skirt coupled to the bare cell while accommodating at least a portion of the upper part of the bare cell; Secondary battery, characterized in that consisting of. The method of claim 1, The battery part is provided with a molded resin accessory or a molded resin mold, The secondary battery according to claim 1, wherein the safety device is fixed by the molded resin part or the molded resin mold in the battery part. The method of claim 1, The combination of the metal skirt and the bare cell is a secondary battery, characterized in that made by laser welding. The method of claim 1, wherein the battery part, A protective circuit board having two external terminals exposed on an upper surface thereof, and an anode connection terminal on a lower surface thereof having a cathode connection terminal to be connected to a cathode of the bare cell and a connection lead to be connected to the bare cell anode; A molding resin component coupled to a lower portion of the protective circuit board and having a hole formed at the center thereof to expose the negative electrode connection terminal; A molded resin case positioned on an upper portion of the protective circuit board and having a hole in which the external terminal portion is removed and a sleeve at a periphery; And a metal skirt having an upper skirt positioned between the molded resin part and the sleeve and a lower skirt formed to be coupled to the bare cell while receiving an upper portion of the bare cell. . The method of claim 4, wherein A positive connection terminal for coupling with the positive terminal of the bare cell in the protective circuit board has a connecting lead protruding downward from the peripheral portion of the protective circuit board, the connecting lead is the upper skirt outside the peripheral portion of the molded resin parts And a secondary battery electrically connected thereto. The method of claim 1, And the battery part is formed through molding resin molding so that a molding resin mold embraces at least a portion of the safety device and the metal skirt. The method of claim 6, The secondary battery of claim 1, wherein at least one through hole is provided at a portion of the metal skirt that is included in the molding resin mold, thereby connecting the inner and outer molding resin molds of the metal skirt. The method of claim 1, A secondary battery, characterized in that the molding resin mold is formed so that a groove is formed in the center of the bottom surface of the molding resin mold to expose the negative electrode connection terminal of the protective circuit board.

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