Title of invention: Terminal bus bar for safety improvement, battery module and battery pack including same
technical field
[One]
The present invention relates to a battery module, and more particularly, to a battery module capable of blocking current flow when a temperature rises. The present invention also relates to a terminal bus bar that can be used for such a battery module, and a battery pack including such a battery module.
[2]
This application is a priority claim application for Korean Patent Application No. 10-2019-0068725 filed on June 11, 2019, and all contents disclosed in the specification and drawings of the application are incorporated herein by reference.
background
[3]
Currently commercialized secondary batteries include a nickel cadmium battery, a nickel hydride battery, a nickel zinc battery, and a lithium secondary battery. Among them, the lithium secondary battery is in the spotlight because of the advantages of free charge and discharge, a very low self-discharge rate, and high energy density because the memory effect hardly occurs compared to a nickel-based secondary battery.
[4]
These lithium secondary batteries mainly use a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. A lithium secondary battery includes an electrode assembly in which unit cells having a structure in which a positive electrode plate in which a positive electrode active material is coated on a positive electrode current collector, a negative electrode plate in which a negative electrode active material is coated on a negative electrode current collector are disposed with a separator interposed therebetween, and the electrode; An exterior material for sealingly housing the assembly together with an electrolyte, that is, a battery case is provided. Lithium secondary batteries are classified into can-type secondary batteries in which an electrode assembly is embedded in a metal can and pouch-type secondary batteries in which an electrode assembly is embedded in a pouch of an aluminum laminate sheet, depending on the shape of the battery case.
[5]
Recently, secondary batteries have been widely used not only in small devices such as portable electronic devices, but also in medium and large devices such as automobiles and power storage systems (ESS). When used in such a medium-large device, a large number of secondary batteries are electrically connected to form a battery module or battery pack in order to increase capacity and output. In particular, a pouch-type secondary battery is widely used in these medium-to-large devices due to advantages such as easy stacking and light weight. The pouch-type secondary battery has a sealed structure in which an electrode assembly to which an electrode lead is connected is accommodated in a pouch case together with an electrolyte. A portion of the electrode lead is exposed to the outside of the pouch case, and the exposed electrode lead is electrically connected to a device in which the secondary battery is mounted or is used to electrically connect the secondary batteries to each other.
[6]
1 shows a part of a battery module manufactured by connecting pouch-type battery cells. For example, a state in which two pouch-type battery cells are connected in series is shown.
[7]
As shown in FIG. 1 , the pouch-type battery cells 10 and 10 ′ include two electrode leads 40 and 40 ′ drawn out of the pouch case 30 . The electrode leads 40 and 40' are divided into a positive (+) lead and a negative (-) lead according to electrical polarity, and are electrically connected to the electrode assembly 20 sealed in the pouch case 30 . That is, the positive lead is electrically connected to the positive plate of the electrode assembly 20 , and the negative lead is electrically connected to the negative plate of the electrode assembly 20 .
[8]
There may be various ways in which the battery cells 10 and 10' are connected in the battery module 1, and FIG. 1 shows that the electrode leads 40 and 40' are bent and then placed on the bus bar 50 and laser welded. A method of connecting the electrode lead 40 of the battery cell 10 and the electrode lead 40 ′ of another battery cell 10 ′ adjacent to the battery cell 10 by welding is illustrated.
[9]
On the other hand, when the lithium secondary battery is overheated, there is a risk of explosion. In particular, as it is applied to electric vehicles including electric vehicles (Electric Vehicles, EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), many high-capacity secondary vehicles In a battery module or battery pack that is used by connecting battery cells, a very serious accident may occur in the event of an explosion, so securing safety is one of the main tasks.
[10]
A representative cause of the rapid increase in the temperature of the lithium secondary battery is when a short-circuit current flows. A short-circuit current is mainly generated when a short circuit occurs in an electronic device connected to a secondary battery, etc., and when a short circuit occurs in a lithium secondary battery, a rapid electrochemical reaction occurs at the positive electrode and the negative electrode to generate heat. Due to the heat generated in this way, the temperature of the battery cell rises rapidly, which eventually causes ignition. In particular, in the case of a battery module or battery pack including a plurality of battery cells, the heat generated in one battery cell is propagated to the surrounding battery cells and affects other battery cells, which increases the risk.
[11]
Conventionally, PTC devices, fuses, and the like have been proposed as means for preventing explosion by blocking current when the temperature inside a secondary battery rises. However, these have a problem in that a separate mounting space is required within the battery module or battery pack.
[12]
Ensuring safety is very important in that the explosion of a battery module or battery pack not only causes damage to electronic devices or vehicles, but also threatens user safety and can lead to fire. When the secondary battery is overheated, the risk of explosion and/or ignition increases, and rapid combustion or explosion due to overheating may cause damage to life and property. Therefore, there is a demand for the introduction of means for sufficiently ensuring safety in the use of the secondary battery.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[13]
SUMMARY OF THE INVENTION An object of the present invention is to provide a component capable of improving the safety of a battery module by blocking current when the temperature rises.
[14]
Another problem to be solved by the present invention is to provide a battery module and a battery pack having improved safety by employing these components.
[15]
Other objects and advantages of the present invention will be set forth below and will be learned by way of example of the present invention. In addition, the objects and advantages of the present invention can be realized by the features and combinations of features indicated in the claims.
means of solving the problem
[16]
The present invention proposes a new terminal bus bar as a component capable of improving the safety of a battery module.
[17]
A terminal bus bar according to the present invention includes a coupling portion having a substantially plate-like shape having a thin thickness compared to a length and a width; and a terminal part bent in a vertical direction at one end of the coupling part. The coupling part consists of a first metal layer/a material layer/second metal layer that is sequentially stacked along the extension direction of the terminal part/a material layer/second metal layer that is normally conductive but can act as a resistance when the temperature rises, and the material layer is decomposed at a certain temperature or higher It contains a gas generating material that increases resistance by generating gas. The first metal layer is integral with the terminal part, and the second metal layer provides a connection surface to the electrode lead of the battery cell.
[18]
In the terminal bus bar, a groove through which the electrode lead passes may be formed in the coupling portion.
[19]
The material layer may include the gas generating material, a conductive material, and an adhesive.
[20]
The gas generating material may be melamine cyanurate.
[21]
The conductive material may be connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive material may be released to increase resistance.
[22]
A method of manufacturing such a terminal bus bar may include the following steps. First, a metal member in which the first metal layer is integral with the terminal part and has an L-shaped cross-section is prepared. The material layer is formed on the first metal layer. Then, a second metal layer is laminated on the material layer.
[23]
When the material layer is formed to include the gas generating material, the conductive material and the adhesive, the step of laminating the second metal layer on the material layer and then pressing may be further included.
[24]
The battery module according to the present invention includes such a terminal busbar.
[25]
The battery module is a battery module including two or more battery cells, wherein the battery cell is a pouch-type secondary battery in which electrode leads of opposite polarities are exposed to the outside of the pouch case, and at least one of the battery cells It further includes a terminal bus bar connected to the electrode lead of the.
[26]
In such a battery module, a current flow path from the outside of the battery module to the battery module may be provided in the order of passing through the terminal part, the first metal layer, the material layer, the second metal layer, and the electrode lead.
[27]
The present invention also provides a battery pack including two or more of these battery modules. The battery pack further includes an inter-bus bar connecting between a terminal part of a terminal bus bar of one of the battery modules and a terminal part of a terminal bus bar of another one of the battery modules in order to connect the battery modules. The battery pack may further include a pack case for packaging the battery modules.
[28]
In addition, the present invention provides an automobile comprising at least one battery pack according to the present invention.
Effects of the Invention
[29]
According to the present invention, the battery module is configured by changing the terminal bus bar while leaving the battery cells as they are. The terminal busbar can block current flow through the terminal busbar by increasing its resistance when the temperature rises. Accordingly, when the battery module according to the present invention is overheated, the current flow may be blocked, thereby ensuring safety in non-ideal situations.
[30]
As a configuration for increasing the resistance of the bus bar, a material layer containing a gas generating material is included in the bus bar so that the current flow is interrupted when the gas generating material reaches a decomposition temperature. Accordingly, even when the secondary battery protection circuit does not operate, it is possible to block the flow of current so that the current does not flow any more, for example, to prevent charging, and thus the safety of the battery module can be improved. As such, the battery module of the present invention implements a means for automatically blocking the flow of current when the temperature rises by improving the bus bar, so it is possible to double secure the safety of the battery module together with the overcharge prevention function of the secondary battery protection circuit have.
[31]
According to the present invention, it is possible to provide a battery module using a terminal bus bar capable of ensuring safety when connecting between battery cells to form an electrical connection path. When an event occurs, such as a situation in which the non-ideal temperature is reached, the gas generating material contained in the material layer in the terminal bus bar is decomposed and the resistance is increased. As a result, the electrical connection of the battery cells is released to block the current flow, so that the safety of the battery module can be secured.
[32]
In particular, by including a material layer containing a gas generating material that increases resistance by decomposing at a predetermined temperature or higher between the first metal layer and the second metal layer in the terminal bus bar to generate a gas, the terminal bus bar and the terminal bus bar centering on this material layer The resistance between the second metal layer, which is a portion to which the electrode lead is connected, and the first metal layer, which is a portion of the terminal bus bar to which the electrode lead is not connected, increases, so that current does not flow. These terminal busbars are especially used to connect between neighboring battery modules. In this way, when a terminal bus bar connecting battery cells between neighboring battery modules is configured, current does not flow through the terminal bus bar when the temperature rises, so safety can be improved.
[33]
According to the present invention, safety is secured by improving the terminal bus bar of the battery module. Only the point of using the terminal bus bar proposed by the present invention instead of the existing terminal bus bar is different and the existing battery module manufacturing process can be used as it is, so there is an advantage in that the safety of the battery module can be secured relatively without changing the process. Since the battery cell itself uses the existing manufacturing process as it is, there is no need for process changes or adjustments to the mass production process.
[34]
As described above, according to the present invention, current flow is secured in a normal situation and battery module performance similar to that of the existing one is exhibited, but the battery module safety can be improved by blocking the current flow when the temperature rises to a certain level or higher due to non-ideal situations. . Therefore, it is possible to improve the safety of the battery module, the battery pack including the same, and the vehicle including the battery pack.
Brief description of the drawing
[35]
The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the detailed description of the present invention to be described later, so that the present invention is described in such drawings should not be construed as being limited only to
[36]
1 schematically shows a conventional battery module.
[37]
2 is a terminal bus bar according to an embodiment of the present invention.
[38]
3 is a terminal bus bar according to another embodiment of the present invention.
[39]
4 schematically illustrates a battery module including a terminal bus bar according to another embodiment of the present invention.
[40]
5 is a front view of a terminal bus bar included in the battery module of FIG. 4 , and FIG. 6 is a cross-sectional view.
[41]
7 is a front view of a bus bar included in the battery module of FIG. 4 .
[42]
8 is a photograph of an experimentally manufactured ICB assembly.
[43]
9 is a view for explaining a battery pack according to another embodiment of the present invention.
[44]
10 is a view for explaining a vehicle according to another embodiment of the present invention.
[45]
11 is a graph showing resistance and temperature according to time of battery modules used in an experiment.
[46]
12A, 12B, 13A, and 13B are external short-circuit test results of battery modules used in an experiment.
Modes for carrying out the invention
[47]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention.
[48]
Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations. In the drawings, like reference numerals indicate like elements.
[49]
In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery is a general term for a secondary battery in which lithium ions act as working ions during charging and discharging to induce an electrochemical reaction in the positive and negative plates.
[50]
On the other hand, even if the name of the secondary battery is changed depending on the type of electrolyte or separator used in the lithium secondary battery, the type of battery case used to package the secondary battery, the internal or external structure of the lithium secondary battery, etc. Any secondary battery used as a lithium secondary battery should be interpreted as being included in the category of the lithium secondary battery.
[51]
The present invention can be applied to other secondary batteries other than lithium secondary batteries. Therefore, even if the working ions are not lithium ions, any secondary battery to which the technical idea of ​​the present invention can be applied should be interpreted as being included in the scope of the present invention regardless of the type.
[52]
Hereinafter, an embodiment of a terminal bus bar according to the present invention will be described with reference to FIGS. 2 and 3 of the accompanying drawings.
[53]
2 is a terminal bus bar according to an embodiment of the present invention. 3 is a terminal bus bar according to another embodiment of the present invention.
[54]
First, referring to FIG. 2 , the terminal bus bar 150 includes a coupling part 160 and a terminal part 170 . The terminal unit 170 is a portion bent in the vertical direction to one end of the coupling unit 160 .
[55]
The coupling portion 160 is a substantially plate-shaped member having a thin thickness (T) compared to the length (L) and width (W). The coupling part 160 is a first metal layer 162 stacked sequentially from bottom to top along the extension direction of the terminal part 170/a material layer 164 that is normally conductive but can act as a resistance when the temperature rises/second made of a metal layer 166 . The first metal layer 162 , the material layer 164 , and the second metal layer 166 are stacked along the thickness (T) direction. The thickness of the terminal unit 170 may be the same as the thickness T of the coupling unit 160 . The first metal layer 162 is integral with the terminal unit 170 , and the second metal layer 166 provides a connection surface to the electrode lead of the battery cell. The terminal unit 170 may be used to connect an external input or between battery modules. In general, since a component that forms an electrical wiring by connecting with an electrode lead is called a bus bar, a component including the coupling part 160 and the terminal part 170 may be called a bus bar, but unlike other bus bars, in addition to the coupling part 160, the terminal part 170 ) because there is a difference in that it further includes a terminal bus bar in the present invention.
[56]
The first metal layer 162 and the second metal layer 166 may include a metal having good electrical conductivity. For example, it may include at least one of aluminum, copper, nickel, and SUS. The first metal layer 162 and the second metal layer 166 may use various materials that can be used as an existing bus bar material. The first metal layer 162 and the second metal layer 166 may be of the same type or different types.
[57]
The material layer 164 sandwiched between the first metal layer 162 and the second metal layer 166 contains a gas generating material that increases resistance by decomposing at a predetermined temperature or higher to generate gas. Preferably, the material layer 164 includes such a gas generating material, a conductive material, and an adhesive. The conductive materials are connected and fixed to each other by an adhesive, and when gas is generated from the gas generating material, the connection of the conductive material is released, thereby increasing resistance. The gas generating material may be a volume expansion resin.
[58]
The gas generating material is preferably melamine cyanurate, which is a type of volume expansion resin. Melamine cyanurate is a material used as a nitrogen and phosphorus-bonded nitrogen-phosphorus flame retardant component, and can be obtained as a raw material with an average particle size of several tens of um through various manufacturers.
[59]
Melamine cyanurate, usually used for flame retardant applications, undergoes endothermic decomposition at temperatures above about 300°C. Melamine cyanurate decomposes into melamine and cyanuric acid. Vaporized melamine releases inert nitrogen gas. By controlling the molecular weight of melamine cyanurate, the decomposition temperature can be controlled. The structural formula of melamine cyanurate is as follows.
[60]
[constitutional formula]
[61]

[62]
The conductive material is not particularly limited as long as it has conductivity, and for example, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, silver, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.
[63]
The adhesive is a component that assists in bonding the gas generating material and the conductive material and the like to the first metal layer 162 and the second metal layer 166 . Examples of such adhesives include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, various copolymers, and the like.
[64]
When the temperature rises above a certain level due to non-ideal circumstances, for example, when the temperature rises above 300° C., melamine cyanurate is decomposed in the material layer 164 inserted between the first metal layer 162 and the second metal layer 166 and N 2 gas is generated. Accordingly, the resistance of the material layer 164 is increased to operate as a resistance layer.
[65]
A method of manufacturing such a terminal bus bar 150 may include the following steps. First, a metal member M in which the first metal layer 162 is integral with the terminal part 170 and has an L-shaped cross-section is prepared. In order to set the overall thickness to the thickness T, the metal member M may be prepared such that the first metal layer 162 is thinner than the terminal part 170 . Such a metal member (M) may be made by processing a metal plate. Then, a material layer 164 is formed on the first metal layer 162 . Then, a second metal layer 166 is stacked on the material layer 164 . The thickness of the material layer 164 and the second metal layer 166 may be set to satisfy the overall thickness T when they are stacked on the first metal layer 162 .
[66]
When the material layer 164 is formed to include the gas generating material, the conductive material, and the adhesive, the step of laminating the second metal layer 166 on the material layer 164 and then pressing may be further included.
[67]
The material layer 164 may be formed by applying a paste or slurry in which the gas generating material, the conductive material, and the adhesive are mixed on the first metal layer 162 . If the second metal layer 166 is placed thereon and pressed from the top and bottom, the terminal bus bar 150 in which the material layer 164 is sandwiched between the two metal layers 162 and 166 can be obtained. If necessary, additional heat treatment may be performed.
[68]
The thickness T of the coupling part 160 may be the same as the thickness of the existing bus bar. The material of the first metal layer 162 and the second metal layer 166 may be the same as that of the existing bus bar. The normal electrical conductivity of the material layer 164 may be made similar to that of the existing bus bar by making the conductive material in the material layer 164 the same as or higher than that of the existing bus bar.
[69]
Accordingly, in a normal situation, the conductivity of the material layer 164 in the terminal bus bar 150 is maintained, so that the battery module performance similar to that when using the conventional bus bar can be expressed. When the temperature rises above a certain level due to a non-ideal situation, since the resistance of the material layer 164 increases, the current flow can be blocked. Accordingly, when the temperature rises, the material layer 164 acts as a resistor to block current, so that safety can be improved in a battery module manufactured including the same.
[70]
The terminal bus bar 150 ′ shown in FIG. 3 is basically the same as the terminal bus bar 150 of FIG. 2 . In the terminal bus bar 150 ′, a groove 168 through which an electrode lead passes is further formed in the coupling portion 160 . The number of grooves 168 may vary depending on the number of electrode leads or a connection method. A hole 172 is further formed in the terminal unit 170 . The hole 172 is used to connect an external input or between battery modules. The number of holes 172 may vary according to a connection method.
[71]
As described above, in the terminal bus bar 150 or 150 ′ provided by the present invention, the portion to which the electrode leads are connected by welding (which can be regarded as the long axis of the bus bar) is made of metal - volume expansion resin + conductive material + adhesive - metal. It has a three-story structure. Under normal circumstances, current can flow between the terminal busbar and the electrode leads, but at high temperatures, the volume expansion resin expands in volume in the volume expansion resin + conductive material + adhesive part, and the space between the conductive materials increases, resulting in increased resistance. For this reason, the resistance between the terminal busbar and the electrode leads increases, making it difficult to flow current. As such, at an abnormal temperature, current does not flow through the terminal bus bar, so the safety of the battery module including the same is improved.
[72]
4 schematically illustrates a battery module including a terminal bus bar according to another embodiment of the present invention. 5 is a front view of a terminal bus bar included in the battery module of FIG. 4 , and FIG. 6 is a cross-sectional view VI-VI′ of FIG. 5 . 7 is a front view of a bus bar included in the battery module of FIG. 4 .
[73]
The battery module 1000 of FIG. 4 shows an example of a 4P3S connection. That is, three cell banks 211 in which four battery cells 210 are connected in parallel (P) are connected in series (S). Each of the battery cells 210 may be a pouch-type battery cell as shown in FIG. 1 above. 4P3S is for illustrative purposes only, and the battery module of the present invention is not limited thereto.
[74]
The battery cell 210 is a secondary battery and includes two electrode leads 240 drawn out of the pouch case 230 . The electrode lead 240 is divided into a positive (+) lead and a negative (-) lead according to electrical polarity, and is electrically connected to an electrode assembly (not shown) sealed in the pouch case 230 . That is, the positive lead is electrically connected to the positive plate of the electrode assembly, and the negative lead is electrically connected to the negative plate of the electrode assembly. As such, the battery cell 210 has a structure in which one end of the electrode lead 240 of the opposite polarity is connected to both ends, respectively, the electrode assembly is received and sealed in the pouch case 230 together with the electrolyte, and the other end of the electrode lead 240 is sealed. The end of the pouch-type secondary battery is exposed to the outside of the pouch case (230).
[75]
The battery cell 210 has electrode leads 240 protruding from both ends thereof. In the cell bank 211 connected in parallel, these electrode leads 240 are stacked so that the same polarity is next to each other. In addition, the cell banks 211 are stacked to have opposite polarities. There may be various ways in which the electrode lead 240 is connected. In FIGS. 4 to 7 , the other end of the electrode lead 240 is bent to the left or right to provide a flat contact surface, and then the bus The bar 290 or the terminal bus bar 150 ′ overlaps each other and is connected by welding.
[76]
4 to 7 , the terminal bus bar 150 ′ connects the electrode leads 240 having the same polarity in one cell bank 211 . The bus bar 290 connects the electrode leads 240 of different polarities between the two cell banks 211 . In this embodiment, two terminal bus bars 150 ′ and two bus bars 290 are provided respectively.
[77]
Between the bent portions of each electrode lead 240 , a terminal bus bar 150 ′ and a bus bar 290 are placed parallel to the stacking direction of the battery cells 210 and are connected to the electrode lead 240 . The connection method may be made by a method conventionally made in the art, for example, may be coupled and connected by ultrasonic welding or laser welding, but is not limited thereto.
[78]
Grooves 168 and 296 through which the electrode lead 240 passes are formed in the terminal bus bar 150 ′ and the bus bar 290 . With respect to the terminal bus bar 150', the description with reference to FIGS. 2 and 3 is applied as it is.
[79]
Referring to FIG. 5 which is a front view of the terminal bus bar 150 ′ and FIG. 7 which is a front view of the bus bar 290 , the grooves 168 and 296 are approximately O-shaped around the grooves 168 and 296 . After the electrode lead 240 penetrates through the grooves 168 and 296 formed in the center and is bent, the electrode lead 240-busbars 150', 290 welding is performed along the long axis of the busbars 150' and 290. proceeds linearly.
[80]
In particular, as shown in FIGS. 4 and 5 , four electrode leads 240 may be coupled to the second metal layer 166 among the coupling portions 160 of one terminal bus bar 150 ′. As such, when the four electrode leads 240 are coupled to the coupling portion 160 of one terminal bus bar 150 ′, two of the four electrode leads 240 are stacked with each other in the groove 168 . It passes through and is bent to the left and connected to the left side of the coupling part 160 , and the other two electrode leads 240 may be bent to the left and connected to the right side of the coupling part 160 .
[81]
In this case, the four electrode leads 240 are provided in four different battery cells 210 , respectively, and have the same polarity. For example, all of the electrode leads 240 connected to the upper right terminal bus bar 150 ′ of FIG. 4 are positive leads. Accordingly, the upper right terminal bus bar 150 ′ in FIG. 4 may be referred to as a positive terminal bus bar. All of the electrode leads 240 connected to the lower left terminal bus bar 150 ′ of FIG. 4 are negative leads. Accordingly, the lower left terminal bus bar 150 ′ in FIG. 4 may be referred to as a negative terminal bus bar.
[82]
4 and 7 , eight electrode leads 240 may be coupled to one bus bar 290 . In this way, when the eight electrode leads 240 are coupled to one bus bar 290 , two of the eight electrode leads 240 are bent to the right in a stacked state to be placed on the left side of the bus bar 290 . are connected, and the other two pass through the left groove 296 of the two grooves 296 in a stacked state and are bent to the right and connected to the left side of the central portion of the bus bar 290 . The other two are stacked on each other, pass through the right groove 296 of the two grooves, are bent to the left, and are connected to the right side of the center of the bus bar 290 . The remaining two electrode leads 240 are bent to the left and connected to the right side of the bus bar 290 .
[83]
At this time, the eight electrode leads 240 are provided in eight different battery cells 210 , respectively, and the left four have the same polarity but the right four have different polarities. For example, the electrode leads 240 connected to the bus bar 290 include four positive leads and four negative leads.
[84]
In particular, a current flow path through the terminal bus bar 150' of the present invention will be described in detail with reference to FIG. 6 . Referring to FIG. 6 , the current flow path from the outside of the battery module (1000 in FIG. 4 ) to the battery module 1000 is the terminal portion 170 of the terminal bus bar 150 ′, the first metal layer 162 , and the material layer ( 164 ), the second metal layer 166 and the electrode lead 240 are provided in the order of passing through. As described above, the material layer 164 is a material that is normally conductive but can act as a resistance when the temperature rises. When the temperature rises above a certain level due to non-ideal circumstances, for example, when the temperature rises above 300° C., melamine cyanurate is decomposed in the material layer 164 and N 2 gas is generated. Accordingly, the resistance of the material layer 164 is increased to operate as a resistance layer. In addition, it may serve to break the electrical connection through volume expansion.
[85]
Accordingly, in a normal situation, the conductivity of the material layer 164 in the terminal bus bar 150 ′ is maintained, so that the performance of the battery module similar to that of the conventional bus bar can be expressed. When the temperature rises above a certain level due to non-ideal circumstances, since the resistance of the material layer 164 increases, the current flowing to the terminal unit 170 and the first metal layer 162 passes through the material layer 164 and the second metal layer 166. It becomes difficult to flow to Accordingly, the current flow to the electrode lead 240 can be blocked. Accordingly, when the temperature rises, the material layer 164 may act as a resistor to block the current. Accordingly, even when the secondary battery protection circuit does not operate, it is possible to block the flow of current so that no more current flows, for example, to prevent charging, and thus the safety of the battery module 1000 can be improved. As such, the battery module 1000 of the present invention implements a means for automatically blocking the flow of current when the temperature rises by improving the terminal bus bar, so the safety of the battery module 1000 is doubled with the overcharge prevention function of the secondary battery protection circuit. There is an effect that can secure . By configuring the terminal bus bar 150 ′ instead of the bus bar 290 in this way, the current flow to the battery module 1000 may be blocked from the outside or from other battery modules.
[86]
A typical cause of deterioration in safety due to a rapid increase in temperature of a lithium secondary battery is short-circuit current, and it is very important to secure safety during a short circuit in the safety of a battery module or battery pack in which several battery cells are connected. The lower the short-circuit resistance, the higher the short-circuit current flows, which generates great heat, and when the battery cell becomes unbearable, ignition occurs. Some safe results are obtained when the short-circuit resistance is very low. This is a case where the heat generated by the flow of a high current exceeds 660°C, and the electrode lead melts, thereby ensuring safety because the current flow is cut off. If the generated temperature is lower than this, the electrode lead does not melt, so high heat is accumulated while the flow of current continues, and the battery cell cannot withstand it, resulting in ignition. On the other hand, there are cases where a high current flows even under normal circumstances. In the case of rapid charging, rapid acceleration, or starting of an electric vehicle, a large current flows in the battery module, which causes high temperature in the electrode lead. To prevent this, it is necessary to block the flow of current at a temperature of about 250°C or higher.
[87]
In this embodiment, when the battery module 1000 reaches about 300° C., gas is generated in the material layer 164 of the terminal bus bar 150 ′ to increase the resistance of the material layer 164 . Accordingly, it does not operate in the normal high current range, but operates only when an actual short circuit occurs and overheats to a higher temperature, thereby securing safety against fire and explosion. In addition, it has the advantage of not reducing energy density as it does not occupy space in the module like other devices for improving safety, such as PTC devices or fuses.
[88]
Since the battery module 1000 according to the present invention has excellent safety, it is also suitable for use as a power source for medium-to-large devices requiring high-temperature stability, long cycle characteristics, and high rate characteristics. Preferred examples of the medium-to-large device include a power tool that moves by being powered by an electric motor; electric vehicles including EVs, HEVs, PHEVs, and the like; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooter); electric golf carts; and ESS, but is not limited thereto.
[89]
The terminal bus bar 150 ′ and the bus bar 290 may have various shapes and sizes to implement various electrical connection relationships. In addition, the terminal bus bar 150 ′ and the bus bar 290 are applied to the battery module manufacturing process as a component called an ICB assembly assembled on a plastic frame in consideration of the wiring relationship rather than being used alone. The shape of the frame and the shape of the bus bar combined with the frame vary depending on the connection relationship between the battery modules. Accordingly, it will be apparent to those skilled in the art that various modifications of the present invention are possible.
[90]
8 shows a photograph of an experimentally manufactured ICB assembly.
[91]
The ICB assembly 300 includes a frame 310 , a bus bar 290 , and a terminal bus bar 150 ′.
[92]
Since the terminal bus bar 150' can be fixed to the frame 310 through piercing, etc., the volume expansion resin is planarly between the first metal layer 162 and the second metal layer 166 as presented in the present invention. + conductive material + adhesive and the same material layer 164 is sandwiched between the volume expansion resin + conductive material + adhesive and the first metal layer 162, the volume expansion resin + conductive material + adhesive and the second metal layer 166 slip or There is no problem of layer separation.
[93]
As such, according to the present invention, safety can be improved by improving the terminal bus bar of the battery module. When the battery module 1000 is manufactured using the terminal bus bar 150 ′ according to the present invention instead of the existing bus bar, the stability is improved, and since the existing battery cell manufacturing process is used as it is, it is necessary to change the process or mass production process. Another advantage is that no adjustment is required.
[94]
As described above, according to the present invention, in a normal situation, the conductivity of the material layer 164 in the terminal bus bar 150 ′ is maintained to express the battery module performance similar to that of the existing battery module, and the temperature is higher than a certain level due to non-ideal situations. The safety of the battery module 1000 may be improved by blocking current flow when rising. Accordingly, the safety of the battery module 1000 , a battery pack including the same, and a vehicle including the battery pack can be improved.
[95]
9 is a view for explaining a battery pack according to another embodiment of the present invention.
[96]
The battery pack 1200 includes two or more battery modules 1000 as described above. The inter-bus bar 1250 connects the terminal units 170 of the terminal bus bar 150 ′ between adjacent battery modules 1000 . That is, the inter-bus bar 1250 is the terminal portion 170 of any one of the two or more battery modules 1000 and the terminal bus bar 150' of the other of the battery modules 1000. The battery modules 1000 are connected by connecting between the terminal parts 170 .
[97]
The inter bus bar 1250 may have a plate shape in contact with the terminal portion 170 of the terminal bus bar 150 ′. In order to simplify the shape of the inter-bus bar 1250, that is, the position of the terminal bus bar 150' in the battery module 1000 may be adjusted so that the neighboring terminal bus bar 150' can be placed at the closest distance. have. For example, the battery module 1000 of FIG. 4 is located at the bottom of FIG. 9 , and the battery module 1000 in which the battery module 1000 of FIG. 4 is formed with left and right mirror symmetry is positioned at the upper end of FIG. 9 . .
[98]
In the structure shown in FIG. 9 , the terminal bus bar 150 ′ located at the upper right side is a negative terminal bus bar. The terminal portion 170 of the terminal bus bar 150' is provided with a negative terminal electrically connected to an external terminal for external input. The two terminal busbars 150' located in the left middle part are a positive terminal busbar and a negative terminal busbar from top to bottom in the drawing. Therefore, the inter-bus bar 1250 is a serial connection between the two terminal bus bars 150' having different polarities. The terminal bus bar 150' on the lower right is a positive terminal bus bar. The terminal portion 170 of the terminal bus bar 150' is provided with a positive terminal electrically connected to an external terminal for external input.
[99]
The connection between the terminal bus bar 150 ′ and the inter bus bar 1250 may be a bolt and nut fastening method using a hole 172 formed in the terminal portion 170 of the terminal bus bar 150 ′. Accordingly, another hole for fastening the bolt and the nut may be provided in the inter-bus bar 1250 at a position corresponding to the hole 172 .
[100]
The battery pack 1200 may further include a pack case for packaging the battery modules 1000 . In addition, the battery pack 1200 according to the present invention includes various devices for controlling charging and discharging of the battery module 1000 in addition to the battery module 1000 and the pack case, such as a battery management system (BMS), a current sensor, and a fuse. and the like may be further included.
[101]
10 is a view for explaining a vehicle according to another embodiment of the present invention.
[102]
The battery pack 1200 may be provided in the vehicle 1300 as a fuel source for the vehicle 1300 . For example, the battery pack 1200 may be provided in the vehicle 1300 in an electric vehicle, a hybrid vehicle, and other manners that may use the battery pack 1200 as a fuel source.
[103]
Preferably, the vehicle 1300 may be an electric vehicle. The battery pack 1200 may be used as an electric energy source for driving the vehicle 1300 by providing a driving force to the motor 1310 of the electric vehicle. In this case, the battery pack 1200 has a high nominal voltage of 100V or more. For hybrid vehicles, it is set to 270V.
[104]
The battery pack 1200 may be charged or discharged by the inverter 1320 according to the driving of the motor 1310 and/or the internal combustion engine. The battery pack 1200 may be charged by a regenerative charging device coupled with a break. The battery pack 1200 may be electrically connected to the motor 1310 of the vehicle 1300 through the inverter 1320 .
[105]
As described above, the battery pack 1200 also includes a BMS. The BMS estimates the states of battery cells in the battery pack 1200 and manages the battery pack 1200 using the estimated state information. For example, state information of the battery pack 1200, such as a state of charge (SOC), a state of health (SOH), a maximum allowable input/output power, and an output voltage of the battery pack 1200 is estimated and managed. In addition, charging or discharging of the battery pack 1200 is controlled by using this state information, and further, it is possible to estimate the replacement time of the battery pack 1200 .
[106]
The ECU 1330 is an electronic control device that controls the state of the vehicle 1300 . For example, torque information is determined based on information such as an accelerator, a brake, and a speed, and the output of the motor 1310 is controlled to match the torque information. In addition, the ECU 1330 sends a control signal to the inverter 1320 so that the battery pack 1200 can be charged or discharged based on state information such as SOC and SOH of the battery pack 1200 received by the BMS. The inverter 1320 allows the battery pack 1200 to be charged or discharged based on the control signal of the ECU 1330 . The motor 1310 drives the vehicle 1300 based on control information (eg, torque information) transmitted from the ECU 1330 using electric energy of the battery pack 1200 .
[107]
The vehicle 1300 includes the battery pack 1200 according to the present invention, and the battery pack 1200 includes the battery module 1000 with improved safety as described above. Accordingly, the stability of the battery pack 1200 is improved, and since the battery pack 1200 has excellent stability and can be used for a long time, the vehicle 1300 including the battery pack 1200 is safe and easy to operate.
[108]
Also, of course, the battery pack 1200 may be provided in other devices such as ESS BMS using a secondary battery in addition to the vehicle 1300 , devices, and facilities.
[109]
As such, the device, apparatus, and facility including the battery pack 1200, such as the battery pack 1200 and the vehicle 1300 according to the present embodiment, includes the battery module 1000 described above, and the battery module described above. A battery pack 1200 having all the advantages due to (100) and an apparatus, apparatus, and equipment such as a vehicle 1300 having such a battery pack 1200 may be implemented.
[110]
The battery module as shown in FIG. 4 was manufactured on a laboratory scale to verify the effect of blocking the current of the terminal bus bar according to the present invention.
[111]
The battery cells constituting the battery module followed a general method of manufacturing a pouch-type battery cell. An embodiment was made using a bus bar including a first metal layer stacked sequentially like the terminal bus bar 150 ′ according to the present invention/a material layer that is normally conductive but can act as a resistance when the temperature rises/a second metal layer is used. . The material layer, which is normally conductive but can act as a resistance when the temperature rises, contains a gas generating material, a conductive material, and an adhesive. Melamine cyanurate was used as a gas generating material, silver (Ag) powder was used as a conductive material, and an epoxy resin was used as an adhesive. The silver content was about 75 to 85 wt%.
[112]
A bus bar made of only one metal layer was used as Comparative Example 1. As Comparative Example 2, a bus bar in which the first metal layer and the second metal layer were adhered with a silver epoxy resin was used. The material of the first metal layer and the second metal layer and the material of the bus bar of Comparative Example 1 were the same. Busbar sizes of Examples and Comparative Examples 1 and 2 were all the same.
[113]
11 is a graph showing resistance and temperature according to time of battery modules used in an experiment. Resistance and temperature change with time were measured while applying an overcurrent of 600A to the battery module. A 1000A class charger was used to apply overcurrent, and a data logger was used for data measurement. The temperature is a measurement of the busbar area of ​​the battery module.
[114]
Referring to FIG. 11 , in Comparative Example 1, the temperature increases almost linearly as time passes, reaching 60° C. after 30 seconds, and in the meantime, although the resistance gradually increases, the current through the bus bar continues to flow. show that In the case of Comparative Example 2, it can be seen that the temperature rises more steeply than in Comparative Example 1 as time elapses, reaching 110° C. after 30 seconds have elapsed. Although the resistance of Comparative Example 2 was gradually increased while maintaining a slightly greater degree than that of Comparative Example 1, it was confirmed that the current through the bus bar continued to flow and there was no overcurrent blocking effect.
[115]
In the example, it can be seen that the resistance increases rapidly after 8 seconds, and after that the resistance is measured to be 0, the overcurrent is blocked and the resistance measurement is not possible. Since the resistance increases and decreases according to the increase of the temperature, as well as the temperature characteristic in which the resistance rapidly increases at a specific temperature, the bus bar according to the present invention can be called a PTC bus bar. As described above, according to the present invention, it was confirmed that the resistance of the bus bar is rapidly increased at a specific point in time, so that the overcurrent blocking effect occurs. 12A, 12B, 13A, and 13B are external short-circuit test results of battery modules used in an experiment. 12A and 12B are the case of Comparative Example 1, and FIGS. 13A and 13B are the case of the Example of the present invention. The external short circuit test was performed by connecting a shunt resistor with a known resistance value to the battery module in parallel, flowing a large current to make a short circuit, and measuring the shunt voltage across the shunt resistor to calculate the current. During the test, the cell voltage was also measured, and the busbar, anode, cathode and cell core temperatures were also measured. Data was measured using a data logger as before.
[116]
12A and 13A are graphs of voltage, temperature, and current according to time, and FIGS. 12B and 13B are enlarged views of the shunt voltage and current when an external short circuit occurs.
[117]
Both FIGS. 12A and 13A show the results of forcibly short-circuiting externally at 10 minutes after the application of the current. As time elapses, in the case of Comparative Example 1 of FIG. 12A, the cell voltage is recovered only to 3.15V, but in the case of the embodiment of FIG. 13A, the cell voltage is recovered to 4.25V. In Comparative Example 1, the recovery of about 1.1 V was less, suggesting that the current was not completely cut off. In fact, looking at FIG. 12b showing the shunt voltage and current at the time of the external short circuit, in Comparative Example 1, it is confirmed that a current of 300 A or more flows after the external short circuit, whereas in FIG. 13B , in the embodiment, the current after the external short circuit is almost 0 it is confirmed that
[118]
Comparing the temperature of the bus bar, it can be seen that in the case of the embodiment of FIG. 13A rather than the case of the comparative example 1 of FIG. 12A , the resistance increases due to the rapid temperature increase in the beginning, and as a result, the current is cut off and hardly flows. In the case of the example, since the current blocking effect is clear, in the case of the example, the temperature after the current cutoff is maintained at almost room temperature, compared to the temperature of the anode and the cathode of Comparative Example 1 rising to around 100°C.
[119]
Through the above experimental results, it can be confirmed that the embodiment of the present application has a more reliable current blocking effect than the comparative examples, and actually achieves the current blocking function when the temperature increases.
[120]
In the above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto and will be described below with the technical idea of ​​the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims.
Claims
[Claim 1]
An approximately plate-shaped coupling portion having a thin thickness compared to the length and width; and a terminal part bent in a vertical direction at one end of the coupling part, wherein the coupling part is a first metal layer sequentially stacked along the extension direction of the terminal part Consisting of a second metal layer, the material layer contains a gas generating material that increases resistance by decomposing at a predetermined temperature or more to generate gas, the first metal layer is integral with the terminal part, and the second metal layer is a battery Terminal busbar, characterized in that it provides a connection surface with the electrode lead of the cell.
[Claim 2]
The terminal bus bar according to claim 1, wherein the material layer includes the gas generating material, a conductive material, and an adhesive.
[Claim 3]
The terminal bus bar according to claim 1, wherein the gas generating material is melamine cyanurate.
[Claim 4]
The terminal bus bar according to claim 2, wherein the conductive materials are connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive materials is released to increase resistance.
[Claim 5]
A method of manufacturing the terminal bus bar according to claim 1, comprising the steps of: preparing a metal member in which a first metal layer is integral with a terminal part and has an L-shaped cross-section; forming a material layer on the first metal layer that is normally conductive but can act as a resistance when the temperature rises; and laminating a second metal layer on the material layer.
[Claim 6]
[Claim 6] The method of claim 5, wherein the material layer is formed of the gas generating material, the conductive material, and the adhesive, and further comprising the step of laminating the second metal layer on the material layer and then pressing it. A method of manufacturing a terminal busbar.
[Claim 7]
A battery module including two or more battery cells, wherein the battery cells are pouch-type secondary batteries in which electrode leads of opposite polarities are exposed to the outside of a pouch case, and are connected to electrode leads of one or more of the battery cells It further includes a terminal bus bar, wherein the terminal bus bar is approximately plate-shaped coupling portion having a thin thickness compared to the length and width; and a terminal part bent in a vertical direction at one end of the coupling part, wherein the coupling part is a first metal layer sequentially stacked along the extension direction of the terminal part Consisting of a second metal layer, the material layer contains a gas generating material that increases resistance by decomposing at a predetermined temperature or higher to generate gas, the first metal layer is integral with the terminal part, and the second metal layer is the Battery module, characterized in that connected to the electrode lead.
[Claim 8]
The battery module according to claim 7, wherein the material layer includes the gas generating material, a conductive material, and an adhesive.
[Claim 9]
The battery module according to claim 7, wherein the gas generating material is melamine cyanurate.
[Claim 10]
The battery module according to claim 8, wherein the conductive materials are connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive materials is released to increase resistance.
[Claim 11]
The method of claim 7, wherein a current flow path from the outside of the battery module to the battery module is provided in the order of passing through the terminal part, the first metal layer, the material layer, the second metal layer, and the electrode lead. battery module.
[Claim 12]
12. A battery module comprising two or more battery modules according to any one of claims 7 to 11, and a terminal portion of a terminal bus bar of any one of the battery modules and a terminal of the other of the battery modules to connect the battery modules. The battery pack further comprising an inter-bus bar connecting between the terminal portions of the bus bar.
[Claim 13]
A motor vehicle comprising at least one battery pack according to claim 12 .