KR101812273B1 - Battery module including bus bar for cutting off current flowing - Google Patents

Abstract

A battery module according to the present invention includes at least one unit cell, a housing accommodating the unit cell, a pair of external terminals exposed to the outside of the housing, and a pair of buses Wherein at least one of the pair of bus bars comprises a first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And an alloy bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate by 90 ° C to 110 ° C; .
According to the present invention, when the protection circuit does not operate normally even though the temperature of the secondary battery rises excessively due to occurrence of a short circuit or overcharging, the bus bar is quickly broken, Lt; / RTI >

Description

[0001] The present invention relates to a battery module including a bus bar for cutting current,

The present invention relates to a battery module with improved safety, and more particularly, to a battery module in which a secondary battery is overheated due to an overcurrent or overcharge due to a short circuit, To a battery module capable of ensuring safety in use.

As the use of portable electric appliances such as video cameras, portable phones, and portable PCs is being activated, the importance of secondary batteries, which are mainly used as driving power sources, is increasing.

Unlike a primary battery, which can not be charged normally, a secondary battery capable of charging and discharging is active in the development of advanced fields such as a digital camera, a cellular phone, a laptop computer, a power tool, an electric bicycle, an electric vehicle, a hybrid vehicle, Research is underway.

In particular, the lithium secondary battery has a higher energy density per unit weight and can be rapidly charged as compared with other secondary batteries such as lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries and nickel-zinc batteries. It is progressing.

The lithium secondary battery has an operating voltage of 3.6 V or higher and can be used as a power source for portable electronic devices, or a plurality of batteries can be connected in series or in parallel to a high output electric vehicle, a hybrid vehicle, a power tool, an electric bicycle, Is used.

The lithium secondary battery has a working voltage three times higher than that of a nickel-cadmium battery or a nickel-metal hydride battery, and has an excellent energy density per unit weight, and is rapidly used.

The lithium secondary battery can be classified into a lithium ion battery using a liquid electrolyte and a lithium ion polymer battery using a polymer solid electrolyte depending on the type of electrolyte. The lithium ion polymer battery can be divided into a fully solid lithium ion polymer battery containing no electrolytic solution and a lithium ion polymer battery using a gel polymer electrolyte containing an electrolyte depending on the kind of polymer solid electrolyte.

In the case of a lithium ion battery using a liquid electrolyte, it is usually used in a form in which a cylinder or a rectangular metal can is used as a container and welded and sealed. Since the can type secondary battery using such a metal can as a container is fixed in shape, there is a disadvantage that it restricts the design of an electrical product using the metal can as a power source, and it is difficult to reduce the volume. Accordingly, a pouch type secondary battery in which an electrode assembly and an electrolyte are sealed in a film pouch packaging material has been developed and used.

However, when the lithium secondary battery is overheated, there is a danger of explosion and it is an important task to secure safety. Overheating of a lithium secondary battery occurs for various reasons, for example, a case where an overcurrent flows beyond a limit through a lithium secondary battery. When the overcurrent flows, the internal temperature of the battery rises rapidly because the lithium secondary battery generates heat by joule heat. Also, the rapid rise of the temperature causes a decomposition reaction of the electrolytic solution and causes a thermal runaway, which eventually leads to the explosion of the battery. The overcurrent is a phenomenon in which a pointed metal object penetrates a lithium secondary battery or the insulation between an anode and a cathode is destroyed by contraction of a separator interposed between an anode and a cathode or a rush current is generated due to an abnormality of an external charging circuit or a load, Is applied to the battery or the like.

Therefore, the lithium secondary battery is used in combination with a protection circuit to protect the battery from an abnormal situation such as the occurrence of an overcurrent, and the protection circuit is provided with a fuse element for irreversibly disconnecting a line through which charging or discharging current flows when an over- .

1 is a circuit diagram for explaining an arrangement structure and an operation mechanism of a fuse element in a structure of a protection circuit combined with a battery pack including a lithium secondary battery.

As shown in the figure, the protection circuit includes a fuse element 1, a sense resistor 2 for sensing an overcurrent, and a fuse element 1 for monitoring the occurrence of an overcurrent to protect the battery pack when an overcurrent occurs. And a switch (4) for switching the flow of an operating current into the fuse element (1).

The fuse element 1 is installed in a main line connected to the outermost terminal of the battery pack. The main line refers to a wiring through which charging current or discharging current flows. In the figure, the fuse element 1 is shown mounted on a high potential line (Pack +).

The fuse element 1 is a three-terminal element part, two terminals are connected to a main line through which a charging or discharging current flows, and one terminal is connected to the switch 4. And a fuse 1a connected in series with the main line and carpetted at a specific temperature, and a resistor 1b for applying heat to the fuse 1a.

The microcontroller 3 periodically detects the voltage across the sense resistor 2 and monitors whether an overcurrent is generated. When it is determined that an overcurrent is generated, the microcontroller 3 turns the switch 4 on. Then, a current flowing in the main line is bypassed to the fuse element 1 and applied to the resistor 1b. Thus, the joule heat generated in the resistor 1b is conducted to the fuse 1a to raise the temperature of the fuse 1a. When the temperature of the fuse 1a rises to the fusing temperature, the fuse 1a is fused, The line is irreversibly disconnected. When the main line is disconnected, the overcurrent does not flow any more, so that the problem caused by the overcurrent can be solved.

However, the above-described conventional techniques have various problems. That is, if a failure occurs in the microcontroller 3, the switch 4 is not turned on even in a state where an overcurrent is generated. In this case, since the current does not flow into the resistor 1b of the fuse element 1, there is a problem that the fuse element 1 does not operate. Further, a space for arranging the fuse element 1 in the protection circuit is separately required, and a program algorithm for controlling the operation of the fuse element 1 must be loaded in the microcontroller 3. Therefore, the space efficiency of the protection circuit is deteriorated and the load of the microcontroller 3 is increased.

Therefore, there is a need for an improved technique for solving such a problem.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a battery module in which a bus bar connecting between a unit cell and an external terminal is configured in a double structure, And a battery module that can ensure safety in use of the secondary battery.

According to an aspect of the present invention, there is provided a battery module including at least one unit cell, a housing accommodating the unit cell, a pair of external terminals exposed to the outside of the housing, Wherein at least one of the pair of bus bars comprises a first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And an alloy bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate by 90 ° C to 110 ° C; .

Wherein the alloy bridge comprises at least one metal selected from the group consisting of gallium (Ga), indium (In), tin (Sn), and bismuth (Bi); And at least one metal selected from the group consisting of aluminum (Al), zinc (Zn), and silver (Ag).

The alloy bridge may contain two or more metals selected from the group consisting of gallium (Ga), indium (In), tin (Sn) and bismuth (Bi).

The alloy bridge may be made of a lead-free alloy containing no lead (Pb).

The first metal plate and the second metal plate may be positioned on the same plane with a predetermined gap therebetween.

The alloy bridge may be directly interposed between the first metal plate and the second metal plate facing each other and be joined to the first metal plate and the second metal plate.

The opposing surface may be tapered to have a concave shape.

The alloy bridge may be bonded to the first metal plate and the second metal plate on either or both sides of the first metal plate and the second metal plate.

Wherein the first metal plate and the second metal plate have receiving grooves formed on at least one surface of an upper surface or a lower surface of one side end of each of the first metal plate and the second metal plate, the alloy bridge having a size and a shape corresponding to the receiving grooves And may be accommodated in the space formed by the mutual engagement of the opposite ends of the first metal plate and the second metal plate, and may be joined to the first metal plate and the second metal plate.

Wherein the first metal plate and the second metal plate have a first bent portion and a second bent portion formed at respective one ends of the first metal plate and the second metal plate facing each other and the alloy bridge is formed by mutual engagement of the first bent portion and the second bent portion The first metal plate and the second metal plate can be accommodated in the formed space and bonded to the first metal plate and the second metal plate.

The first metal plate and the second metal plate are provided with receiving grooves formed at a predetermined depth from surfaces facing each other, and the alloy bridge can be joined to the metal plate by inserting one end and the other end of the alloy bridge into the receiving groove, respectively .

One side of each of the first metal plate and the second metal plate is positioned so that at least a part of the first metal plate and the second metal plate are opposed to each other and the alloy bridge can be interposed in the opposite region and bonded to the first metal plate and the second metal plate .

One side of each of the first metal plate and the second metal plate is positioned so that at least a part thereof overlaps and faces each other, and the alloy bridge can be formed on one side and the other side of the circumference of the opposite region facing each other.

One side of each of the first metal plate and the second metal plate is positioned so that at least a part thereof overlaps and faces each other, and the alloy bridge may be formed on the entire circumference of the facing area.

A bus bar connected to a cathode of the unit cell among the pair of bus bars includes a first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And an alloy bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate by 90 ° C to 110 ° C; . ≪ / RTI >

According to the present invention, when the protection circuit does not operate normally even though the temperature of the secondary battery rises excessively due to occurrence of a short circuit or overcharging, the bus bar is quickly broken, Lt; / RTI >

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a circuit diagram for explaining an arrangement structure and an operation mechanism of a fuse element in a configuration of a protection circuit coupled with a battery module.
2 is a perspective view illustrating a battery module according to an embodiment of the present invention.
3 is a partial perspective view showing the bus bar shown in Fig.
4 to 12 are partial perspective views showing various modifications of the bus bar shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only some of the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

2 and 3, a battery module 100 according to an embodiment of the present invention will be described.

FIG. 2 is a perspective view showing a battery module according to an embodiment of the present invention, and FIG. 3 is a partial perspective view showing a bus bar shown in FIG.

2 and 3, a battery module 100 according to an embodiment of the present invention includes at least one unit cell 10, a housing 20 for housing the unit cell 10, a housing 20, A pair of external terminals 20a exposed to the outside of the unit cell 10 and a pair of bus bars 30 connecting between the unit cell 10 and the external terminal 20a.

The unit cell 10 includes an electrode assembly (not shown) and a pair of electrode leads (not shown) extending from the electrode assembly, that is, a positive electrode lead and a negative electrode lead. have. When there are a plurality of the unit cells 10, the unit cells 10 may be connected in series and / or in parallel by coupling between the electrode leads.

The pair of external terminals 20a are mounted on the outer surface of the housing 20 or through the outer surface of the housing 20 and are connected to an external device (Not shown) and the battery module 100. The battery module 100 may be connected to the battery module 100 through a connection terminal.

Next, the bus bar 30 will be described with reference to Figs. 2 and 3. Fig.

The pair of bus bars 30 connect the electrode leads of the unit cell 10 and the external terminals 20a and are connected to the first metal plate 31, the second metal plate 32, and the metal plate 31 And 32, respectively.

The metal plates 31 and 32 of the bus bar 30 coupled to the positive electrode leads of the pair of bus bars 30 are preferably formed of aluminum (Al) material generally used for the positive electrode lead. This is to improve the weldability and to minimize the contact resistance at the joint portion when the cathode lead and the bus bar 30 are welded together. Similarly, the metal plates 31 and 32 of the bus bar 30, which are coupled with the negative electrode leads of the pair of bus bars 30, are coated with copper (Cu) or nickel (Ni) It is preferably made of a copper material. However, since the other configurations of the pair of bus bars 30 are substantially the same except for the material of the metal plates 31 and 32, in describing the present invention, only one bus bar 30 And a duplicate description of the other will be omitted.

The first metal plate 31 and the second metal plate 32 are spaced apart from each other with a gap therebetween and are located on the same plane, and are formed of a thin plate-shaped metal. The first metal plate 31 may be joined to one end of the electrode lead by welding. The second metal plate 32 is spaced apart from the first metal plate 31 by a gap therebetween and may be coupled with the external terminal 20a by welding or bolt / nut tightening.

The alloy bridge 33 fills the gap between the metal plates 31 and 32 and is electrically connected to the opposite surfaces of the metal plates 31 and 32 to electrically connect the metal plates 31 and 32.

The alloy bridge 33 has a lower melting point than the metal plates 31 and 32. When the battery module 10 is overheated due to a short circuit or overcharging, 2 metal plates 32, thereby ensuring safety in use of the secondary battery.

The alloy bridge 33 is a lead-free alloy containing no lead (Pb) which is harmful to human body and is made of at least one selected from the group consisting of gallium (Ga), indium (In), tin (Sn) and bismuth (Bi) And an alloy component containing at least one metal selected from the group consisting of aluminum (Al), zinc (Zn) and silver (Ag). In addition, the alloy bridge 33 may be made of an alloy component containing two or more metals selected from the group including gallium, indium, tin and bismuth.

The alloy bridge 33 may be adjusted to have a melting point of 90 ° C to 110 ° C depending on the composition ratio of the contained metal. This melting point range corresponds to a lower melting point of aluminum, copper or nickel coated copper constituting the metal plates 31 and 32 as well as lower melting point due to heat transmitted from the superheated unit cell 10 Since it corresponds to the range that can be promoted, rapid current interruption due to temperature rise is possible.

This melting point range is determined by the maximum voltage and maximum current conditions that the bus bar 30 must withstand, the level of the overcurrent to be cut off using the alloy bridge 33, the electrical properties required for the bus bar 30 Conductivity) and / or mechanical properties (tensile strength).

If the melting point of the alloy bridge 33 is lower than 90 캜, the bus bar 30 may be broken even in a normal range of heat generated by the normal operation of the battery module 100. On the contrary, if the melting point of the alloy bridge 30 is higher than 110 ° C, there is a problem that it is difficult to fully expect the effect of preventing the accident due to overheating of the battery module 100.

As a practical example, in the case where the alloy bridge 33 is composed of 62.5 wt% of bismuth and 37.5 wt% of tin and has a melting point of 94.4 캜, the bus bar 30 to which such an alloy bridge 33 is applied It can be observed that the battery module 100 is quickly broken when the battery module 100 is not broken in a normal use state and the pair of external terminals 20a are short-circuited.

In the drawings of the present invention, all of the pair of bus bars 30 have a double structure in which the alloy bridge 33 is applied, but the present invention is not limited thereto. That is, it is needless to say that any one of the pair of bus bars may be a bus bar 30 including an alloy bridge 33, and the other may be a bus bar of a general structure. Further, in the case where only one of the pair of bus bars has a structure including the alloy bridge 33, a bus bar, which is generally combined with a negative lead having a larger calorific value, has a double structure including such an alloy bridge 33 .

Next, various modifications of the bus bar 30 will be described with reference to FIGS. 4 to 12. FIG.

4 to 12 are partial perspective views showing various modifications of the bus bar shown in FIG.

The structure of the bus bar 30 shown in Fig. 4 differs from the structure shown in Fig. 3 in that the mutually facing surfaces of the metal plates 31 and 32 are in the shape of an inclined surface which is tapered. In this case, the contact area between the metal plates 31 and 32 and the alloy bridge 33 is further increased, thereby enhancing the binding force between the metal plates 31 and 32 and the alloy bridge 33, It has an effect of reducing the contact resistance.

5, the first metal plate 31 and the second metal plate 32 are positioned on the same plane with a certain gap therebetween, and the alloy bridge 33 is disposed on the metal plates 31 and 32, And is joined to the metal plates 31 and 32. [ 5, only the case where the alloy bridge 33 is formed on the upper surface of the metal plates 31 and 32 is shown, but it is also possible to form the alloy bridge 33 on the lower surface. 6, the alloy bridge 33 may be formed on both the upper surface and the lower surface of the metal plates 31 and 32. In this case, It can have an effect of strengthening.

Referring to FIG. 7, the first metal plate 31 and the second metal plate 32 are located on the same plane with a predetermined gap therebetween, and are provided with receiving grooves RG1 ). On the other hand, the alloy bridge 33 has a size and shape corresponding to the receiving groove RG1 and is received in a space formed by mutual engagement of opposite ends of the metal plate, and is joined to the metal plates 31 and 32 . 7 shows only the case where the receiving groove RG1 is formed on the upper surface of the metal plates 31 and 32. However, it is also possible to form the receiving groove RG1 on the lower surface or on both the upper surface and the lower surface.

Referring to FIG. 8, the first metal plate 31 and the second metal plate 32 are positioned on the same plane with a predetermined gap therebetween, and are provided with first bent portions (31 ') and a second bend (32'). Meanwhile, the alloy bridge 33 is accommodated in the space formed by the interlocking of the first bent portion 31 'and the second bent portion 32', and is bonded to the metal plates 31 and 32.

Referring to FIG. 9, the first metal plate 31 and the second metal plate 32 are positioned on the same plane with a predetermined gap therebetween. The receiving grooves RG2 ). On the other hand, the alloy bridge 33 is inserted into the receiving groove RG2 at one end and the other end, and is joined to the metal plates 31 and 32.

The structure shown in Figs. 7 to 9 is different from the structure shown in Figs. 5 and 6 in that the contact area between the metal plates 31 and 32 and the alloy bridge 33 is widened so that the metal plates 31 and 32 and the alloy Not only the effect of enhancing the bonding force between the bridges 33 but also the effect of reducing the contact resistance can be brought about.

10, one side of each of the first metal plate 31 and the second metal plate 32 is at least partially overlapped and positioned to face each other, and an alloy bridge 33 is disposed over the entire opposite region And is joined to the metal plates 31 and 32.

The structure shown in Figs. 11 and 12 differs from the structure shown in Fig. 10 in that the area of the alloy bridge 33 interposed between the metal plates 31 and 32 is different. That is, the alloy bridge 33 is formed only on one side and the other side of the periphery of the region where the metal plates 31 and 32 face each other. In this case, when the battery module 100 is overheated, the bus bar 30 can be quickly broken.

Although not shown in the drawing, the alloy bridge 33 may be formed on the entire circumference of the opposite region. In this case, a faster breaking effect can be expected as compared with the structure shown in Fig. 10, and the bonding force between the metal plates 31, 32 and the alloy bridge 33 is further enhanced as compared with the structure shown in Figs. The effect can be expected.

As described above, the battery module 100 according to the embodiment of the present invention includes the double-structure bus bar 30 connected between the metal plates 31 and 32 by an alloy bridge 33 having a low melting point. Therefore, when the battery module 100 is overheated due to a short circuit or overcharging, the bus bar 30 can be quickly broken, thereby ensuring safety in use. Particularly, when the battery module 100 is applied to the bus bar 30, which is a component provided outside the housing 20, the current blocking means is less likely to cause ignition and explosion Thereby reducing the risk of damage.

In addition, since the range of the melting point of the alloy bridge 33 applied to the battery module 100 corresponds to the range where the melting of the alloy bridge 33 can be promoted by the heat transmitted from the overheated unit cell 10, The safety in use of the secondary battery can be more assuredly ensured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

100: Battery module
10: unit cell 20: housing
20a: external terminal 30: bus bar
31: first metal plate 32: second metal plate
33: Alloy bridge

Claims (12)

A plurality of unit cells, a housing accommodating the plurality of unit cells, a pair of external terminals exposed to the outside of the housing, and electrode leads provided in the unit cell closest to each external terminal among the plurality of unit cells, A battery module comprising a pair of bus bars connecting between external terminals,
Wherein at least one of the pair of bus bars is provided with:
A first metal plate;
A second metal plate positioned to be spaced apart from the first metal plate; And
And an alloy bridge connecting the first metal plate and the second metal plate,
The alloy bridge has a melting point lower than that of the first metal plate and the second metal plate and is made of indium (In) and tin (Sn). The content of indium is relatively higher than that of tin, RTI ID = 0.0 > 110 C, < / RTI &
Wherein each of the first metal plate and the second metal plate is disposed in parallel along a longitudinal direction with a predetermined gap therebetween,
Wherein the first metal plate and the second plate have receiving grooves formed on at least one surface of an upper surface or a lower surface of each of the opposite end portions,
Wherein the alloy bridge has a size and a shape corresponding to the receiving grooves and is accommodated in a space formed by mutual engagement of opposite ends of each of the first metal plate and the second metal plate, A metal plate,
Wherein a surface of the alloy bridge is coplanar with a surface of the first metal plate and a surface of the second metal plate. delete delete delete delete delete delete delete delete delete delete The method according to claim 1,
A bus bar connected to a cathode of the unit cell among the pair of bus bars,
A first metal plate;
A second metal plate positioned to be spaced apart from the first metal plate; And
An alloy bridge connecting between the first metal plate and the second metal plate, the alloy bridge having a melting point lower than the metal plate by 90 ° C to 110 ° C; The battery module comprising:

Images