KR20090055844A - Battery pack containing printed circuit board employed with conductive pattern - Google Patents

Abstract

A battery pack is provided to ensure fast reaction speed by high current and to efficiently secure the safety of a battery by fusion cutting fused part in conducting high current due to conductive patterns formed with a fuse-cutting part with high resistance. A battery pack comprises a battery cell where an electrode assembly of a positive electrode/separation film/negative electrode structure is accommodated with electrolyte inside the battery case; and a protection circuit board(200) electrically connected to the battery cell. The conductive pattern(400) containing a fuse-cutting part(410) with high resistance is equipped at a connection part of a circuit on a printed circuit board. The fuse-cutting part cuts blocks current by being fuse-cut in conducting of high current.

Description

Battery pack including a protective circuit board with a conductive pattern {Battery pack Containing Printed Circuit board Employed with Conductive Pattern}

The present invention relates to a battery pack, and more particularly, a battery cell in which an electrode assembly having a cathode / separation membrane / cathode structure is sealed inside an battery case together with an electrolyte, and a protective circuit board electrically connected to the battery cell ( A battery pack including a PCB), wherein a portion of a circuit interconnected on the PCB is formed with a conductive pattern including a relatively high resistance cutout that cuts and melts current when a large current is applied. It provides a battery pack.

As the development and demand for mobile devices increases, the demand for secondary batteries as a source of energy is increasing rapidly. Among these secondary batteries, a lot of researches are being conducted on commercially available lithium secondary batteries with high energy density and high discharge voltage. It is used.

In particular, the lithium secondary battery is classified into a cylindrical battery, a square battery, a pouch type battery, and the like according to its appearance, and may be classified into a lithium ion battery and a lithium ion polymer battery according to the type of electrolyte. Due to the recent trend toward miniaturization of mobile devices, there is an increasing demand for thinner rectangular batteries and pouch-type batteries.

However, the lithium secondary battery contains various combustible materials, and there is a danger of overheating or explosion due to overcharging, overcurrent, other physical external impact, etc., and thus has a serious safety drawback. That is, when a lithium secondary battery is exposed to high temperature, or a large current flows within a short time due to overcharging, an external short circuit, nail penetration, local crush, etc., the battery is heated by IR heat to ignite / There is a risk of explosion.

As the temperature of the battery rises, the reaction between the electrolyte and the electrode is accelerated. As a result, heat of reaction is generated to further increase the temperature of the battery, which in turn accelerates the reaction between the electrolyte and the electrode. Thus, the temperature of the battery rises rapidly, which in turn accelerates the reaction between the electrolyte and the electrode. Due to such a vicious cycle, a thermal runaway phenomenon in which the temperature of the battery rises rapidly occurs, and when the temperature rises to a certain level or more, the battery may ignite. In addition, as a result of the reaction between the electrolyte and the electrode, gas is generated to increase the battery internal pressure, and the lithium secondary battery explodes above a certain pressure. The risk of ignition / explosion can be said to be the most fatal drawback of lithium secondary batteries.

Therefore, essential considerations for the development of a lithium secondary battery are to ensure safety. As part of efforts to secure such safety, there are a method of mounting a safety element on the outside of the cell and using a material inside the cell. PTC devices, CID devices, temperature protection circuits, and safety vents using changes in the breakdown voltage of the battery are examples of the former. The latter is the addition of substances that can be changed chemically and electrochemically.

However, the safety devices mounted on the outside of the cell do not provide safety when the flammable gas is already filled inside the cell due to an abnormal battery, and the CID device may be applied only to a cylindrical battery. In addition, it is known that a fast response time such as internal short circuit, bed penetration, local damage, etc. is not properly protected.

One method of using a substance inside a cell is to add an additive that improves safety to an electrolyte or an electrode. Chemical safety devices have the advantage that they can be applied to all kinds of batteries do not require additional processes and space, but has the problem that the performance of the battery is degraded due to the addition of materials. As such a material, a material that forms a passivation layer on the electrode, a material that increases the resistance of the electrode while volume expansion occurs when the temperature rises, and the like have been reported. However, each of them has a problem in that by-products are generated when the passivation layer is formed, thereby degrading the performance of the battery or having a large volume in the battery, which leads to a decrease in the capacity of the battery. Is not used.

In this regard, Japanese Patent Application Laid-Open No. 2005-143160 is connected between a potential input terminal of a protection circuit and a terminal voltage supply line for supplying a terminal voltage of a secondary battery to the protection circuit, and installed in the terminal voltage supply line. Then, a technique relating to a battery pack having an overcurrent limiting circuit for limiting the overcurrent flowing through the terminal voltage supply line is disclosed. However, such a battery pack needs to use a separate conductive member to connect the terminal voltage supply line and the overcurrent limiting circuit, and a connection process thereof is required, and the protection element is protected by the resistance value of the overcurrent limiting circuit itself installed in the terminal voltage supply line. As the threshold of the detectable current or voltage is increased, there is a risk that the safety of the battery cell may be operated at the stage just before the explosion exceeding the threshold level, thereby ensuring safety.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After in-depth study and various experiments, the inventors of the present application form a conductive pattern including a relatively high-resistance melted portion that cuts and melts the current when the large current is energized at the site where the circuits are interconnected on the PCB. In this case, it is not necessary to install a safety device having a predetermined volume to cut off the overcurrent, so that the internal space of the battery can be efficiently used, and the response speed by the large current is very fast, so that the safety of the battery can be efficiently ensured. The present invention has been completed.

Accordingly, the battery pack according to the present invention includes a battery cell in which an electrode assembly having a cathode / separation membrane / cathode structure is sealed inside an battery case together with an electrolyte, and a protective circuit board (PCB) electrically connected to the battery cell. A battery pack comprising: a conductive pattern including a relatively high resistance cutout portion formed at a portion where circuits are interconnected on the PCB to melt and cut current when a large current is applied to block a current. Consists of.

That is, in the battery pack according to the present invention, since the conductive pattern for blocking the overcurrent is printed on the PCB and implemented as a circuit, the occupied space for mounting a separate safety device having a predetermined volume is unnecessary. Therefore, since the internal space of the battery can be minimized, the volume density of the battery can be relatively increased, and the battery pack assembly process can be simplified. In addition, the melted portion can cut off the flow of current immediately by melting and cutting in response to the change of the current at the time of energizing a large current, it is possible to ensure the safety of the battery with high operating reliability.

As defined above, the present invention is characterized in that a melting part having a relatively high resistance is included in the conductive pattern. The high resistance of the melt is not a problem in normal operation of the battery, but in the case of an abnormal operating state, for example, an external short in which a large current of several tens of amps flows, relatively large heat generation occurs. As a result, since a large current is melted and cut to prevent the battery from energizing, it operates as a safety element of the battery cell. This principle is described in detail below.

In general, the relationship between the resistance and the current and the calorific value is expressed by the following Equation 1.

W = I ² x R (1)

In the above formula, W represents a calorific value, I represents a current, and R represents a resistance.

In addition, the resistance is inversely proportional to the cross-sectional area as in Equation 2 below.

R ∝ 1 / A (2)

Wherein R represents resistance and A represents the cross-sectional area.

That is, since the heat generation amount of the melt part rapidly increases as the resistance increases, as in Equation 1, when the large current occurs, the heat generation amount increases as the resistance of the melt part increases, so that the melt may be immediately melt-cut at the time of energization of the large current. Therefore, the current can be cut off quickly before the safety of the battery reaches the threshold level by energizing a large current.

In consideration of this, the melted portion may be configured to have a high resistance value.

In one preferred example, the melted portion may be configured to have a low current density, and for this purpose, a method of reducing the cross-sectional area of the conductive pattern may be considered. In this regard, it is more appropriate to change the width of the conductive pattern since it is substantially very difficult to adjust the height of the conductive pattern. Accordingly, the melted portion may have a structure that is formed to have a smaller width relative to the entire width of the conductive pattern.

That is, the amount of heat generated by the conductive pattern during the overcurrent increases rapidly as in Equation 1, and the increase is doubled in the melt portion, which is a small portion. Therefore, the blow-out portion can be easily cut with a large amount of heat, thereby ensuring battery safety in an overcurrent environment due to abnormal operation of the battery.

However, if the width of the melted portion is too small, the output loss in the normal operating state is large due to the high resistance, which is inefficient, and the melt can be easily melted and cut by a relatively low calorific value, thereby lowering the operating reliability. On the contrary, if the width of the melt portion is too large, it is difficult to automatically cut when an overcurrent occurs, so that the desired effect is difficult to be achieved. In consideration of this, the width of the melted portion may be 10 to 90% with respect to the average width of the conductive pattern, preferably 30 to 80%.

The narrow edge part structure may be manufactured by forming indentations of various shapes on one or both sides of the edge part. The indentation may include a round type, a notch type, a square type, or the like, but is not limited thereto. In addition, the number of the said melting parts is not specifically limited, You may form two or more as needed.

The conductive pattern may be part of a protective circuit pattern printed on a PCB, and may be made of gold (Au) that is commonly used in a protective circuit pattern due to excellent electrical conductivity.

In one preferred example, the conductive pattern may be made of a metal having a higher resistivity than the protective circuit pattern printed on the PCB. In addition, only the melting part may be made of a metal having a high specific resistance.

Here, a metal having a high specific resistance does not mean only a metal having a high absolute value of specific resistance, but a concept including a metal having a relatively high resistivity compared to a metal forming a protective circuit pattern on a PCB or a metal forming another portion of a conductive pattern. to be. The high resistivity metal has an electrical conductivity that does not interfere with energization in a normal operating state of the battery, and examples thereof include tin or a tin alloy, but are not limited thereto.

The method for forming the conductive pattern is not particularly limited and is possible by a known pattern forming method such as photolithography.

The structure of the battery pack according to the present invention is not particularly limited as long as it includes a battery cell and a PCB, and can be applied to various known structures, and there is no particular limitation. The battery cell may be a cylindrical battery, a square battery, a pouch-type battery, and the like, and the PCB may be equipped with various safety elements to configure a protection circuit module (PCM). The PCM may include a field effect transistor (FET) as a switching element for controlling the energization of current, a passive element such as a voltage detector, a resistor, a capacitor, and the like.

As one preferred example of the battery pack according to the present invention,

The battery cell has an electrode assembly embedded in a metal can with an electrolyte, and an open top of the metal can is sealed by a top cap;

An insulating cap mounted on the top and mounted on the top cap of the battery cell, and an insulating cap coupled to the upper end of the battery cell while surrounding the insulating mounting member in the state where the PCM is mounted;

The top cap is provided with a pair of protruding electrode terminals (first protruding electrode terminal and second protruding electrode terminal) respectively connected to the positive electrode and the negative electrode of the electrode assembly, and the insulating mounting member and the PCM Through grooves corresponding to the protruding electrode terminals are formed, respectively, and the protruding electrode terminals are inserted into and fixed in the through holes of the insulating mounting member and the PCM, thereby fixing the insulating mounting member for the battery cell and the PCM. Coupling can be made.

As described above, the battery pack does not need to separately install a safety device having a predetermined volume for blocking the overcurrent, and a pair of protruding electrode terminals are coupled to each other to form an insulating mounting member and a protection circuit. It can be achieved by being inserted into and fixed in the through grooves of the module in series and thus has a very compact structure. Therefore, the volume density of the battery can be relatively increased by minimizing unnecessary waste of space. In addition, it can be assembled by a simple coupling method, easy mechanical fastening, simplify the manufacturing process, and achieve a very stable coupling structure against external shock, vibration and the like.

An end of the protruding electrode terminal may be fixed to the protective circuit module by rolling it in a state protruding to a predetermined length on the upper surface of the protective circuit module. Specifically, a pair of protruding electrode terminals are formed in the top cap in a structure that is connected to the positive electrode and the negative electrode of the battery cell, respectively, and then continuously inserted into the insulating mounting member and the through grooves of the PCM, and the top surface of the PCM. By a series of simple processes of rolling the end of the electrode terminal protruding from it, the coupling and electrical connection of the insulating mounting member and the PCM to the battery cell can be simultaneously achieved.

The protruding electrode terminals may be, for example, conductive conductive rivet structures, and are not particularly limited as long as they are easily inserted into the through holes of the protective circuit module and the insulating mounting member. , Oval or square may be formed, and the rolling of the protruding electrode terminal ends may further improve the bonding force between the insulating mounting member and the PCM to the battery cell.

Further, the material of the protruding electrode terminal is not particularly limited as long as it is a material having high conductivity as the electrode terminal. Preferably, Cu, Ni, and / or Cr plated steel, stainless steel, aluminum, Al alloy, Ni alloy, Cu alloy or Cr alloy. If the protruding electrode terminal is formed integrally with the top cap, it is of course made of the same material as the top cap.

On the other hand, the protruding electrode terminals may serve to additionally facilitate the manufacture of the battery cell and simplify the structure, in addition to the role of fixing the protective circuit module and the insulating mounting member to the top of the battery cell. It may be made of a structure.

For example, at least one of the protruding electrode terminals may have a hollow structure including a through passage communicating with an inside of the battery case. The through passage may be used as an electrolyte injection hole for injecting an electrolyte after mounting an electrode assembly in a battery case during a battery cell manufacturing process. That is, since the protruding electrode terminal itself is utilized as the electrolyte injection hole, it is not necessary to form a separate electrolyte injection hole on the top cap as in the conventional battery cell. Therefore, the through passage may be used as an electrolyte injection hole, for example, and may have a structure sealed by a metal ball.

The protruding electrode terminals may be variously applied regardless of the type and shape of the battery cell. For example, in the case of a square battery cell, the first protruding electrode terminal may be electrically connected to the top cap. The second protruding electrode terminal may be connected to the positive electrode, and may be connected to the negative electrode of the battery cell in an electrically insulated state from the top cap. Accordingly, the first protruding electrode terminal may serve as a positive electrode terminal, and the second protruding electrode terminal may serve as a negative electrode terminal.

In the above structure, the first protruding electrode terminal may be a structure formed integrally with the top cap. That is, the first protruding electrode terminal may be formed at the same time as the top cap in the process of press molding the top cap. However, of course, the separately prepared protruding terminal may be formed by coupling to the top cap, and for example, a separate protruding terminal may be coupled to the top cap by welding. However, in consideration of manufacturing processability and the like, a method of forming the protruding electrode terminal by the former press molding is more preferable.

In another example, the top cap is formed with a through hole; The second protruding electrode terminal includes a plate-shaped body, an upper extension vertically extending upwardly of the main body, and a lower extension portion inserted into the through hole of the top cap and vertically extending downwardly of the main body; In the state where the lower extension of the second protruding electrode terminal is inserted into the through hole of the top cap, the second protruding electrode terminal may be rolled to couple the second protruding electrode terminal to the top cap.

By the coupling structure of the top cap and the protruding electrode terminals as described above, the electrode terminals can be more easily and stably coupled to the top cap, and the upper and lower extensions of the protruding electrode terminals are a protection circuit for the battery cell. The combination of the module and the insulating mounting member can be more firmly and stably maintained.

The insulating mounting member may be further coupled to the battery cell by an adhesive method using an adhesive so as to ensure a more stable mounting state to the top cap.

The present invention also provides a protection circuit board (PCB) in which a protection circuit for controlling overcharging, overdischarging, and overcurrent of a battery cell is formed, wherein the circuit is interconnected and melt-cut at high current to cut off current. It relates to a protective circuit board, characterized in that a conductive pattern including a melt portion having a relatively high resistance is formed.

Through this, it is possible to efficiently secure the safety of the battery cell without affecting the volume density of the battery, it is possible to block the flow of current at a high speed during the large current through the high resistance of the melt.

1 is a schematic front view of a protection circuit module (PCM) mounted to a battery cell according to an embodiment of the present invention.

Referring to FIG. 1, a protection circuit module (PCM) 150 includes a protection circuit board (PCB) 200, a protection circuit 210 printed on the protection circuit board 200, an FET, a voltage detector, and a resistor. And a conductive pattern 400 including various elements 300 such as a capacitor and a blown-out portion 410.

The protection circuit board 200 has a structure in which a protection circuit 210 for electrically connecting the mounted elements and controlling overcharge, overdischarge, overcurrent, etc. of the battery is printed on the rectangular structure of the epoxy composite. The protection circuit board 200 is further provided with a terminal connection portion 220 that can be coupled to an electrode terminal of a battery cell (not shown). The terminal connection part 220 may be directly coupled to the electrode terminal, or may be coupled to the electrode terminal by a separate conductive connection member (not shown) such as a nickel plate.

All of the protection circuits 210 printed on the protection circuit board 200 are ultimately electrically connected to an external input / output terminal (not shown) and the terminal connection unit 220.

Since the conductive pattern 400 is printed on the protective circuit board 200 as a part of the protective circuit 210, the current flow in the circuit is blocked when an overcurrent occurs, thereby blocking the electric current between the external input / output terminal and the battery cell. . In the drawing, the conductive pattern 400 is exemplarily represented as a circuit in which one end is directly connected to the terminal connection part 220, but the external input / output terminal and the terminal connection part 200 are formed on an arbitrary part of the circuit connected to each other. Of course there may be.

The conductive pattern 400 includes elliptical melt ends 410 on both sides, and the melt ends 410 are formed to have a smaller width than the entire width. The melted part 410 of this structure has a relatively low current density and high resistance, so that a large amount of heat is generated during high current energization. Therefore, the molten cut portion 410 at the time of energization of a large current can ensure the safety of the battery by blocking the current bar is melt cut by such heat generation. Meanwhile, the conductive pattern 400 may be made of gold (Au) having excellent conductivity, or may be made of a metal having a relatively high resistivity value such as tin. In addition, the shape of the melted edge may be various, such as notched, rectangular, circular, and the number of melted edges may also be one or two or more.

2 is an exploded perspective view schematically showing a battery pack 100 according to an embodiment of the present invention.

2, the battery pack 100 according to the present invention, the battery pack 100 according to the present invention, the battery cell 130, the battery case in which the electrode assembly is embedded in the battery case together with the electrolyte solution. Top cap 120 for sealing the top end, the protection circuit module 150 of the PCB structure is formed a protective circuit, the insulating mounting member 140 mounted on the top cap 120 of the battery cell 130, the protection circuit The insulating cap 160 coupled to the upper end of the battery cell 130 and the lower cap 170 mounted to the lower end of the battery cell 130 while surrounding the insulating mounting member 140 while the module 150 is mounted. It consists of.

The pair of protruding terminals 112 and 114 includes a first protruding electrode terminal 112 and a second protruding electrode terminal 114 protruding upward in both directions of the upper end of the top cap 120. . The insulating mounting member 140 has through grooves 142 and 144 formed in shapes and sizes corresponding to lower ends of the protruding electrode terminals 112 and 114, and the protruding electrodes in the protection circuit module 150. Through grooves 152 and 154 having a shape and size corresponding to the upper ends of the terminals 112 and 114 are formed.

The first protruding terminal 112 is connected to the positive electrode (not shown) of the battery cell 130 in an electrically connected state with the top cap 120, and the second protruding terminal 114 is the top cap 120. It is connected to the negative electrode (not shown) of the battery cell 130 in an electrically insulated state.

The combination of the insulating mounting member 140 and the protection circuit module 150 with respect to the battery cell 130 includes the through grooves in which the protruding electrode terminals 112 and 114 are formed at both sides of the insulating mounting member 140. This is achieved by inserting the through holes 152 and 154 formed on both sides of the field 142 and 144 and the protection circuit module 150, and then rolling the ends of the protruding electrode terminals 112 and 114. . The bonding of the insulating mounting member 140 to the top cap 120 may be further enhanced by the adhesive added therebetween.

The insulating cap 160 is coupled to the upper end of the battery cell 130 while wrapping the insulating mounting member 140 in the state in which the protective circuit module 150 is mounted, so as to surround the outer surface of the upper end of the battery cell 130. It extends downward to a predetermined length. The lower cap 170 is attached to the lower end of the battery cell 150.

In the battery pack 100 of this structure, the PCM 150 may be electrically connected to the electrode terminal directly without a separate connection member, the lower surface of the PCM 150 as shown in FIG. Since a pattern (not shown) is printed as part of the protection circuit, it is not necessary to mount a safety element for blocking the overcurrent having a predetermined volume. That is, the battery pack 100 of the present invention can have a very compact structure by eliminating the space wasted due to the electrical connection and the mounting of the safety device, it is possible to relatively increase the volume density of the battery.

Although described with reference to the drawings according to an embodiment of the present invention, those of ordinary skill in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, the battery pack according to the present invention is formed with a conductive pattern formed with a high-melting resistance, so that the reaction speed is very fast due to a large current, and the safety of the battery can be efficiently reduced by melt cutting of the melt during energization of a large current. It can be secured.

1 is a front view of a protection circuit module (PCM) in a battery pack according to an embodiment of the present invention;

2 is an exploded perspective view of a battery pack according to an embodiment of the present invention.

Claims (16)

A battery pack including a battery cell in which an electrode assembly having a cathode / membrane / cathode structure is sealed in an interior of a battery case together with an electrolyte, and a protective circuit board (PCB) electrically connected to the battery cell, the circuit on the PCB Is connected to each other, the battery pack, characterized in that a conductive pattern including a relatively high resistance cut-off portion is formed by melting and cutting off the current when a large current is energized. The battery pack as claimed in claim 1, wherein the melted portion has a high resistance due to a low current density. The battery pack as claimed in claim 2, wherein the blow-out portion is formed to have a smaller width relative to the entire width of the conductive pattern. The battery pack as claimed in claim 3, wherein the melt portion has a width of 10 to 90% of the total width of the conductive pattern. The method of claim 1, wherein the conductive pattern is a battery pack, characterized in that part of the protective circuit pattern printed with gold (Au) on the PCB. The battery pack as claimed in claim 1, wherein the melted portion is made of a metal having high specific resistance. The battery pack as claimed in claim 3, wherein the conductive pattern is made of a metal having a higher specific resistance than a protective circuit pattern printed on a PCB. The battery pack according to claim 6 or 7, wherein the high resistivity metal is tin (Sn) or a tin alloy. The method of claim 1, The battery cell has an electrode assembly embedded in a metal can with an electrolyte, and an open top of the metal can is sealed by a top cap; An insulating cap mounted on the top and mounted on the top cap of the battery cell, and an insulating cap coupled to the upper end of the battery cell while surrounding the insulating mounting member in the state where the PCM is mounted; The top cap is provided with a pair of protruding electrode terminals (first protruding electrode terminal and second protruding electrode terminal) respectively connected to the positive electrode and the negative electrode of the electrode assembly, and the insulating mounting member and the PCM Through grooves corresponding to the protruding electrode terminals are formed, respectively, and the protruding electrode terminals are inserted into and fixed in the through holes of the insulating mounting member and the PCM, thereby fixing the insulating mounting member for the battery cell and the PCM. Battery pack characterized in that the coupling is made. The battery pack according to claim 9, wherein an end of the protruding electrode terminal is rolled in a state protruding to a predetermined length on an upper surface of the protective circuit module and fixed to the protective circuit module. 10. The method of claim 9, wherein at least one of the protruding electrode terminals has a hollow structure including a through passage communicating with the inside of the battery case, wherein the through passage is used as an electrolyte injection hole and sealed by a metal ball. A battery pack characterized by the above. 10. The battery cell of claim 9, wherein the first protruding electrode terminal is connected to the positive electrode of the battery cell in an electrically connected state with the top cap, and the second protruding electrode terminal is electrically insulated from the top cap. Battery pack, characterized in that connected to the negative electrode. The battery pack according to claim 9, wherein the first protruding electrode terminal is formed integrally with the top cap. The method of claim 9, The top cap is formed with a through hole, The second protruding electrode terminal includes a plate-shaped main body, an upper extension vertically extending upwardly to an upper portion thereof, and a lower extension portion inserted into a through hole of the top cap and vertically extending downwardly to the lower portion of the main body. At the interface between the through-hole of the second protruding terminal and the top cap is an electrically insulating gasket for mutual insulation, the end of the lower extension portion is rolled to couple the protruding electrode terminal to the top cap. Battery pack. The battery pack as claimed in claim 9, wherein the insulating mounting member is coupled to the battery cell by an adhesive method. A protection circuit board (PCB) in which a protection circuit for controlling overcharging, overdischarging, and overcurrent of a battery cell is formed. The circuit has a relatively high resistance to cut off current by melting and cutting current when a large current is applied to the interconnected portions. A protective circuit board comprising a conductive end portion is formed.

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