阅读说明：本技术 提高安全性的端子汇流排及包括其的电池模块和电池组 (Terminal bus bar for improving safety, and battery module and battery pack comprising same ) 是由 李汉荣 尹汝敏 于 2020-01-06 设计创作，主要内容包括：提供了一种作为提高电池模块的安全性的部件的端子汇流排以及包括该端子汇流排的电池模块和电池组。根据本公开内容的端子汇流排包括耦接部和端子部,所述耦接部大致为板状且厚度小于长度和宽度,所述端子部在所述耦接部的一端在垂直方向上弯折。所述耦接部在所述端子部的延伸方向上包括以相继顺序堆叠的第一金属层、材料层和第二金属层,所述材料层在正常条件下是导电的,但当温度升高时能充当电阻,并且所述材料层包括气体产生材料,所述气体产生材料在预定温度或更高温度下分解而产生气体,因此增大电阻。所述第一金属层与所述端子部一体成形,并且所述第二金属层提供与所述电池单元的电极引线连接的表面。(Provided are a terminal bus bar as a means for improving the safety of a battery module, and a battery module and a battery pack including the same. A terminal bus bar according to the present disclosure includes a coupling portion having a substantially plate shape and a thickness smaller than a length and a width, and a terminal portion bent in a vertical direction at one end of the coupling portion. The coupling portion includes a first metal layer, a material layer, and a second metal layer stacked in a sequential order in an extending direction of the terminal portion, the material layer being conductive under a normal condition but capable of acting as a resistance when a temperature increases, and the material layer including a gas generating material that is decomposed at a predetermined temperature or more to generate a gas, thereby increasing the resistance. The first metal layer is integrally formed with the terminal part, and the second metal layer provides a surface to which an electrode lead of the battery cell is connected.)

1. A terminal bus bar, comprising:

a coupling portion having a substantially plate shape and a thickness less than a length and a width; and

a terminal portion bent in a vertical direction at one end of the coupling portion;

wherein the coupling portion includes a first metal layer, a material layer, and a second metal layer stacked in a sequential order in an extending direction of the terminal portion, the material layer being conductive under a normal condition but capable of acting as a resistance when a temperature increases,

the material layer includes a gas generating material that decomposes at a predetermined temperature or higher to generate a gas, thereby increasing the electric resistance, and

the first metal layer is integrally formed with the terminal part, and the second metal layer provides a surface to which an electrode lead of the battery cell is connected.

2. The terminal buss bar of claim 1, wherein the material layer comprises the gas generating material, a conductive material, and an adhesive.

3. The terminal buss of claim 1, wherein the gas generant material is melamine cyanurate.

4. The terminal bus bar according to claim 2, wherein the conductive material is connected and fixed by the adhesive, and when gas is generated, the connection of the conductive material is disconnected and the resistance is increased.

5. A method for manufacturing the terminal bus bar of claim 1, comprising:

preparing a metal member having an L-shaped section, the metal member having a first metal layer integrally formed with a terminal portion;

forming a material layer on the first metal layer, wherein the material layer is conductive under normal conditions but can act as a resistor when the temperature is increased; and

stacking a second metal layer on the material layer.

6. The method of claim 5, wherein the material layers comprise the gas-generating material, a conductive material, and a binder, and

the method further includes pressing to bond the second metal layer together after stacking them on the material layer.

7. A battery module including at least two battery cells, wherein the battery cells are pouch-type secondary batteries including electrode leads of opposite polarities exposed to the outside of a band-shaped case, the battery module further comprising:

a terminal bus bar connected to the electrode lead of at least one of the battery cells,

the terminal bus bar includes:

a coupling portion having a substantially plate shape and a thickness less than a length and a width; and

a terminal portion bent in a vertical direction at one end of the coupling portion,

wherein the coupling portion includes a first metal layer, a material layer, and a second metal layer stacked in a sequential order in an extending direction of the terminal portion, the material layer being conductive under a normal condition but capable of acting as a resistance when a temperature increases,

the material layer includes a gas generating material that decomposes at a predetermined temperature or higher to generate a gas, thereby increasing the electric resistance, and

the first metal layer is integrally formed with the terminal portion, and the second metal layer is connected to the electrode lead.

8. The battery module of claim 7, wherein the material layer comprises the gas-generating material, a conductive material, and an adhesive.

9. The battery module of claim 7, wherein the gas generating material is melamine cyanurate.

10. The battery module according to claim 8, wherein the conductive material is connected and fixed by the adhesive, and when gas is generated, the connection of the conductive material is broken and resistance is increased.

11. The battery module according to claim 7, wherein a current flow path from the outside of the battery module into the battery module sequentially passes through the terminal part, the first metal layer, the material layer, the second metal layer, and the electrode lead.

12. A battery pack including at least two battery modules according to any one of claims 7 to 11, the battery pack further comprising:

an intermediate bus bar connecting the terminal portion of the terminal bus bar of any one battery module to the terminal portion of the terminal bus bar of another battery module so as to connect the battery modules.

13. A vehicle comprising at least one battery pack according to claim 12.

Technical Field

The present disclosure relates to a battery module, and more particularly, to a battery module that stops current flow when temperature rises. Further, the present disclosure relates to a terminal bus bar for use in a battery module and a battery pack including the same.

This application claims priority to korean patent application No. 10-2019-0068725, filed in korea on 11.6.2019, the disclosure of which is incorporated herein by reference.

Background

Currently, commercially available secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium secondary batteries, and the like. Among these batteries, the lithium secondary battery has little or no memory effect, and receives much attention over the nickel-based secondary battery due to the advantages of being rechargeable at any convenient time, having a very low self-discharge rate, and having a high energy density.

Lithium secondary batteries mainly use lithium-based oxides and carbon materials for positive and negative active materials, respectively. A lithium secondary battery includes an electrode assembly in which a plurality of unit cells each including a positive electrode plate having a positive electrode current collector coated with a positive electrode active material, a negative electrode plate having a negative electrode current collector coated with a negative electrode active material, and a separator interposed between the positive and negative electrode plates, and a hermetically sealed encapsulant or battery case in which the electrode assembly is received together with an electrolyte solution. The lithium secondary battery is classified into a can type secondary battery in which an electrode assembly is placed in a metal can, and a pouch type secondary battery in which an electrode assembly is placed in a pouch of an aluminum laminate sheet, according to the shape of a battery case.

Recently, secondary batteries are widely used not only in small-sized devices such as portable electronic products but also in medium-and large-sized devices such as vehicles and Energy Storage Systems (ESS). For application in medium-and large-sized devices, a number of secondary batteries are electrically connected to construct a battery module or battery pack to increase capacity and output. In particular, pouch-type secondary batteries are widely used in medium-and large-sized devices because they are easily stacked and are lightweight. The pouch-type secondary battery has a structure in which an electrode assembly, to which electrode leads are connected, is received in a pouch-shaped case together with an electrolyte solution, and the pouch-shaped case is hermetically sealed. A portion of the electrode leads is exposed to the outside of the pouch-shaped case, the exposed electrode leads are electrically connected to a device to which the secondary batteries are mounted, or the exposed electrode leads are used to electrically connect the secondary batteries to each other.

Fig. 1 illustrates a portion of a battery module manufactured by connecting pouch type battery cells. For example, two pouch type battery cells connected in series are shown.

As shown in fig. 1, the pouch-type battery cell 10,10 'has two electrode leads 40,40' extending outside the pouch case 30. The electrode leads 40,40' are classified into positive (+) and negative (-) leads according to polarity, and are electrically coupled to the electrode assembly 20 sealed within 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.

There are many connection methods of the battery cells 10,10' in the battery module 1, and fig. 1 illustrates that the electrode leads 40,40' are bent, the electrode leads 40,40' are placed on the bus bars 50, and laser welding is performed to connect the electrode lead 40 of the battery cell 10 and the electrode lead 40' of the battery cell 10' adjacent to the battery cell 10.

Meanwhile, the lithium secondary battery may explode when overheated. In particular, in electric vehicle applications including Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), in the case of a battery module or a battery pack used by connecting a plurality of high-capacity secondary battery cells, explosion may cause a very large accident, and thus it is very important to ensure safety.

The main cause of the rapid increase in the temperature of the lithium secondary battery is the flow of short-circuit current. A short-circuit current generally occurs when a short circuit occurs in an electronic device connected to a secondary battery and when a short-circuit phenomenon occurs in a lithium secondary battery, and a rapid electrochemical reaction occurs in a positive electrode and a negative electrode to generate heat. The temperature of the battery cell increases at a very high rate due to heat, and eventually, fires. In particular, in the case of a battery module or a battery pack including a plurality of battery cells, heat generated from any one battery cell is diffused outward and affects adjacent battery cells, causing a greater risk.

In order to cut off current to avoid explosion when the internal temperature of the secondary battery rises, Positive Temperature Coefficient (PTC) devices and fuses have been proposed. However, a separate installation space is required in the battery module or the battery pack.

Explosion of the battery module or the battery pack may cause damage to an electronic device or a vehicle using the battery module or the battery pack, and in addition, threatens safety of a user and may cause a fire, and thus, it is very important to ensure safety. When the secondary battery is overheated, the risk of explosion and/or fire increases, and rapid combustion or explosion occurring due to overheating may cause loss of personnel and loss of property. Thus, there is a need to improve safety during use of a secondary battery in a manner.

Disclosure of Invention

Technical problem

The present disclosure is directed to providing a means for cutting off current when temperature rises to improve safety of a battery module.

The present disclosure is also directed to providing a battery module and a battery pack having improved safety using the same.

These and other objects and advantages of the present disclosure will be understood by the following description and will be apparent from the embodiments of the present disclosure. Further, it will be readily understood that the objects and advantages of the present disclosure are achieved by means of the instrumentalities and combinations set forth in the appended claims.

Technical scheme

The present disclosure proposes a new terminal bus bar as a means for improving the safety of a battery module.

A terminal bus bar according to the present disclosure includes a coupling portion having a substantially plate shape and a thickness smaller than a length and a width, and a terminal portion bent in a vertical direction at one end of the coupling portion. The coupling portion includes a first metal layer, a material layer, and a second metal layer stacked in a sequential order in an extending direction of the terminal portion, the material layer being conductive under a normal condition but capable of acting as a resistance when a temperature increases, and the material layer including a gas generating material that is decomposed at a predetermined temperature or more to generate a gas, thereby increasing the resistance. The first metal layer is integrally formed with the terminal part, and the second metal layer provides a surface to which an electrode lead of the battery cell is connected.

The terminal bus bar may have an opening in the coupling part, through which the electrode lead passes.

The material layer may include the gas generating material, a conductive material, and a binder.

The gas generating material may be melamine cyanurate.

The conductive material may be connected and fixed by an adhesive, and when gas is generated, the connection of the conductive material may be disconnected and the resistance may be increased.

A method for manufacturing a terminal bus bar may include the following steps. First, a metal member having an L-shaped cross section is prepared, the metal member having a first metal layer integrally formed with a terminal portion. And forming a material layer on the first metal layer. Additionally, a second metal layer is stacked on the material layer.

When the material layer includes a gas generating material, a conductive material, and an adhesive, the method may further include pressing to bond the second metal layer together after stacking them on the material layer.

A battery module according to the present disclosure includes the terminal bus bar.

The battery module includes at least two battery cells, wherein the battery cells are pouch type secondary batteries including electrode leads of opposite polarities exposed to the outside of a band-shaped case, and the battery module further includes terminal bus bars connected to the electrode leads of at least one of the battery cells.

In the battery module, a current flow path from the outside of the battery module into the battery module may pass through the terminal part, the first metal layer, the material layer, the second metal layer, and the electrode lead in this order.

The present disclosure further provides a battery pack including at least two battery modules. The battery pack further includes an intermediate bus bar that connects the terminal portion of the terminal bus bar of any one battery module to the terminal portion of the terminal bus bar of another battery module so as to connect the battery modules. The battery pack may further include an assembly case to enclose the battery module.

Further, the present disclosure provides a vehicle comprising at least one battery pack according to the present disclosure.

Advantageous effects

According to the present disclosure, a battery module is constructed by changing terminal bus bars while leaving battery cells intact. When the temperature rises, the resistance of the terminal bus bar increases to cut off the current flowing through the terminal bus bar. Thus, the battery module according to the present disclosure may cut off current when overheating occurs in use, thereby ensuring safety in an abnormal situation.

In order to increase the electrical resistance of the busbar, the busbar comprises a layer of material containing a gas generating material, the current being cut off when the temperature at which the gas generating material decomposes is reached. Thus, even if the secondary battery protection circuit is not operated, the current can be cut off so that the current no longer flows, for example, the secondary battery is prevented from being charged, thereby improving the safety of the battery module. The battery module of the present disclosure has an improved bus bar to automatically cut off current when the temperature rises, thereby achieving an overcharge prevention function of a secondary battery protection circuit and securing safety of the battery module.

According to the present disclosure, a battery module using terminal bus bars may be provided for safety when connecting battery cells to form an electrical connection path. When an event such as a case of reaching an abnormal temperature occurs, since the gas generating material included in the material layer within the terminal bus bar is decomposed, the resistance increases. As a result, the electrical connection of the battery cells is disconnected and the current is cut off, thereby securing the safety of the battery module.

In particular, between a first metal layer and a second metal layer in a terminal bus bar connected to an electrode lead at the second metal layer and not connected to the electrode lead at the first metal layer, a material layer including a gas generating material that decomposes at a predetermined temperature or higher to generate gas is disposed to increase resistance between the second metal layer and the first metal layer through the material layer, thereby preventing current from flowing. The terminal bus bars are used, in particular, to connect adjacent battery modules. If the terminal bus bars connect the battery cells between the adjacent battery modules, current does not flow through the terminal bus bars when the temperature rises, thereby improving safety.

According to the present disclosure, safety may be ensured by improving the terminal bus bars of the battery module. The proposed terminal bus bar is used instead of the existing terminal bus bar, and the existing battery module manufacturing process can be used, so that the safety of the battery module can be ensured without a great change in the process. Since the battery cell itself uses the existing manufacturing process, there is no need to change the process or adjust the mass production process.

As described above, according to the present disclosure, current is allowed to flow in a normal condition, thereby providing battery module performance similar to that of the conventional battery module, and in an abnormal condition, when the temperature rises above a predetermined level, the current is cut off, thereby improving the safety of the battery module. Thus, the safety of the battery module, the battery pack including the battery module, and the vehicle including the battery pack may be improved.

Drawings

The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the disclosure described below, serve to provide a further understanding of the technical aspects of the disclosure, and therefore the disclosure should not be construed as being limited to the accompanying drawings.

Fig. 1 schematically illustrates a conventional battery module.

Fig. 2 illustrates a terminal bus bar according to an embodiment of the present disclosure.

Fig. 3 illustrates a terminal bus bar according to another embodiment of the present disclosure.

Fig. 4 schematically illustrates a battery module including a terminal bus bar according to another embodiment of the present disclosure.

Fig. 5 is a front view of a terminal bus bar included in the battery module of fig. 4, and fig. 6 is a sectional view.

Fig. 7 is a front view of a bus bar included in the battery module of fig. 4.

Fig. 8 is a photographic image of an experimentally fabricated interconnect board (ICB) assembly.

Fig. 9 is a diagram illustrating a battery pack according to still another embodiment of the present disclosure.

Fig. 10 is a diagram showing a vehicle according to still another embodiment of the present disclosure.

Fig. 11 is a graph showing the change in resistance and temperature with time of the battery modules used in the experiment.

Fig. 12a, 12b, 13a and 13b show external short test results of the battery modules used in the experiments.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation.

Therefore, the embodiments described herein and the drawings shown in the drawings are only the best embodiments of the present disclosure and are not intended to fully describe the technical aspects of the present disclosure, and thus it should be understood that other equivalents and modifications may be made thereto at the time of filing this application. In the drawings, like numbering represents like elements.

In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery is collectively referred to as a secondary battery, in which lithium ions serve as working ions during charge and discharge, thereby inducing electrochemical reactions at positive and negative electrode plates.

Meanwhile, it should be noted that the lithium secondary battery covers any secondary battery using lithium ions as working ions even though the name of the secondary battery varies with the type of electrolyte or separator used in the lithium secondary battery, the type of battery case for enclosing the secondary battery, and the internal or external structure of the lithium secondary battery.

The present disclosure may also be applied to secondary batteries other than lithium secondary batteries. Thus, it should be noted that the present disclosure encompasses any type of secondary battery to which the technical aspects of the present disclosure can be applied, even if the working ions are not lithium ions.

Hereinafter, a terminal bus bar embodiment of the present disclosure will be described with reference to fig. 2 and 3.

Fig. 2 illustrates a terminal bus bar according to an embodiment of the present disclosure. Fig. 3 illustrates a terminal bus bar according to another embodiment of the present disclosure.

First, referring to fig. 2, the terminal bus bar 150 includes a coupling portion 160 and a terminal portion 170. The terminal portion 170 is a portion bent in a vertical direction at one end of the coupling portion 160.

The coupling portion 160 is a substantially plate-shaped member whose thickness T is small with respect to the length L and the width W. The coupling portion 160 includes a first metal layer 162, a material layer 164, and a second metal layer 166 sequentially stacked from bottom to top in an extending direction of the terminal portion 170, and the material layer 164 is conductive under normal conditions and may function as a resistance when temperature increases. The first metal layer 162, the material layer 164, and the second metal layer 166 are stacked in the thickness T direction. The thickness of the terminal portion 170 may be equal to the thickness T of the coupling portion 160. The first metal layer 162 is integrally formed with the terminal part 170, and the second metal layer 166 provides a surface to which electrode leads of the battery cell are connected. The terminal part 170 may be used for external input or for connection between the battery modules. In general, a member connected to the electrode lead to form an electrical wiring is referred to as a bus bar, and thus a member including the coupling portion 160 and the terminal portion 170 may be referred to as a bus bar, but unlike other bus bars, the member includes the terminal portion 170 in addition to the coupling portion 160, and due to this difference, the member is referred to as a terminal bus bar in the present disclosure.

The first and second metal layers 162 and 166 may include metals having high electrical conductivity. For example, the first and second metal layers 162 and 166 may include at least one of aluminum, copper, nickel, and SUS. The first and second metal layers 162 and 166 may include various types of materials used as existing bus bar materials. The first metal layer 162 and the second metal layer 166 may be of the same type or different types.

The material layer 164 sandwiched between the first metal layer 162 and the second metal layer 166 includes a gas generating material that decomposes at a predetermined temperature or higher to generate gas and increase resistance. Preferably, the material layer 164 includes a gas generating material, a conductive material, and an adhesive. The conductive material is connected and fixed by the adhesive, and when the gas generating material generates gas, the connection of the conductive material can be disconnected, so that the resistance can be increased. The gas generating material may be a volume expandable resin.

The gas generating material is preferably melamine cyanurate, which is a type of volume expandable resin. Melamine cyanurate is a material used as a nitrogen-phosphorus flame retardant containing a combination of nitrogen and phosphorus, and raw materials having an average particle size on the order of tens of micrometers are available from different manufacturers.

Melamine cyanurate, which is mainly used as a flame retardant, undergoes endothermic decomposition at temperatures above 300 ℃. Melamine cyanurate decomposes into melamine and cyanuric acid. The evaporated melamine releases inert nitrogen. The decomposition temperature is adjusted by adjusting the molecular weight of the melamine cyanurate. The structural formula of the melamine cyanurate is as follows.

[ structural formula ]

The conductive material is not limited to any particular type of material having conductive properties, and may include, for example: graphite, such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, ketone black, channel black, furnace black, lamp black and thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as fluorocarbon, aluminum, silver, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

The adhesive is a substance that helps to adhere the gas generating material and the conductive material and to the first metal layer 162 and the second metal layer 166. Examples of the binder may include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

In abnormal situations, when the temperature is increased above a predetermined level, for example, above 300 ℃, the melamine cyanurate in the material layer 164 disposed between the first metal layer 162 and the second metal layer 166 decomposes to produce N₂And (4) qi. Thus, the resistance of the material layer 164 increases and acts as a resistive layer.

The method for manufacturing the terminal bus bar 150 may include the following steps. First, the metal member M is prepared such that the first metal layer 162 is integrally formed with the terminal portion 170 and the cross section thereof has an L shape. In order to make the total thickness to be the thickness T, the metal member M may be made to be thinner than the terminal portion 170 by the first metal layer 162. The metal member M may be prepared by processing a metal plate. Thereafter, a material layer 164 is formed on the first metal layer 162. Additionally, a second metal layer 166 is stacked on the material layer 164. The thickness of each of the material layer 164 and the second metal layer 166 may be set such that the total thickness satisfies the thickness T when the material layer 164 and the second metal layer 166 are stacked on the first metal layer 162.

When the material layer 164 includes the gas generating material, the conductive material, and the adhesive, the method may further include pressing to adhere the second metal layer 166 together after stacking them on the material layer 164.

A paste or slurry prepared by mixing a gas generating material, a conductive material, and a binder may be applied on the first metal layer 162 to form the material layer 164. When second metal layer 166 is placed on material layer 164 and second metal layer 166 is pressed up and down, terminal bus 150 having material layer 164 disposed between two metal layers 162,166 is obtained. Additional heat treatments may be performed as necessary.

The thickness T of the coupling portion 160 may be equal to that of the conventional bus bar. The first and second metal layers 162 and 166 may be made of the same material as the existing bus bar. When the conductive material in the material layer 164 is equal to or higher than the existing bus bar material, the conductivity of the material layer 164 may become similar to that of the existing bus bar under normal conditions.

Thus, under normal conditions, the conductivity of the material layer 164 in the terminal bus bar 150 is maintained, so that the battery module performance exhibits a level similar to that when an existing bus bar is used. In an abnormal situation, when the temperature rises above a predetermined level, the resistance of the material layer 164 increases and is sufficient to cut off the current. Thus, when the temperature increases, the material layer 164 serves as a resistor to cut off current, thereby improving the safety of the battery module including the material layer 164.

The terminal bus bar 150' shown in fig. 3 is substantially the same as the terminal bus bar 150 of fig. 2. The terminal bus bar 150' further includes an opening 168 in the coupling part 160, and the electrode lead passes through the opening 168. The number of the openings 168 may be different according to the number of electrode leads or a connection method. The terminal portion 170 further includes a hole 172. The holes 172 are used for external input or for connection between the battery modules. The number of holes 172 may vary depending on the method of attachment.

The present disclosure provides a terminal bus bar 150 or 150' having a triple structure of metal- (volume expandable resin + conductive material + adhesive) -metal, in which electrode leads are connected by soldering (corresponding to the long axis of the bus bar). Under normal circumstances, current may flow between the terminal bus bar and the electrode lead, but the volume-expandable resin + conductive material + volume-expandable resin in the binder expands in volume at high temperature, forming a gap in the conductive material, resulting in an increase in resistance. Thus, the resistance between the terminal bus bar and the electrode lead increases, which blocks the current. As described above, the current is prevented from flowing through the terminal bus bars at abnormal temperatures, and thus the battery module including the terminal bus bars has improved safety.

Fig. 4 schematically illustrates a battery module including a terminal bus bar according to another embodiment of the present disclosure. Fig. 5 is a front view of a terminal bus bar included in the battery module of fig. 4, and fig. 6 is a sectional view of fig. 5 taken along line VI-VI'. Fig. 7 is a front view of a terminal bus bar included in the battery module of fig. 4.

The battery module 1000 of fig. 4 has a 4P3S connection. That is, three battery banks 211 are connected in series S, and each battery bank 211 includes four battery cells 210 connected in parallel P. Each battery cell 210 may be a pouch type battery cell as shown in fig. 1. 4P3S is provided by way of illustration, but the battery module of the present disclosure is not limited thereto.

The battery cell 210 is a secondary battery, and has two electrode leads 240 extending to the outside of the band-shaped case 230. The electrode lead 240 is divided into a positive (+) lead and a negative (-) lead according to polarity, and is electrically connected to an electrode assembly (not shown) received in the hermetically sealed pouch case 230. That is, the positive lead is electrically connected to the positive electrode plate of the electrode assembly, and the negative lead is electrically connected to the negative electrode plate of the electrode assembly. As described above, the battery cell 210 is a pouch-type secondary battery in which one end of the electrode lead 240 of opposite polarity of the battery cell 210 is connected to each of both ends of an electrode assembly, the electrode assembly is received in the pouch case 230 together with an electrolyte solution, the pouch case 230 is tightly sealed, and the other end of the electrode lead 240 is exposed to the outside of the pouch case 230.

The electrode leads 240 extend out of both ends of the battery cell 210. In the parallel-connected battery row 211, the electrode leads 240 are stacked such that the electrode leads 240 of the same polarity are arranged next to each other. In addition, between the cell rows 211, the electrode leads 240 are stacked in opposite polarities. There are many methods to connect the electrode leads 240, and fig. 4 to 7 show that the other ends of the electrode leads 240, which are placed on the bus bars 290 or the terminal bus bars 150' and connected by soldering, are bent to the left or right to provide flat contact surfaces.

Referring to fig. 4 to 7, the terminal bus bar 150' connects electrode leads 240 of the same polarity in one cell line 211. The bus bar 290 connects the electrode leads 240 of opposite polarities between the two battery bars 211. In this embodiment, two terminal busbars 150' and two busbars 290 are provided.

The terminal bus bars 150' and the bus bars 290 are disposed between the bent portions of the respective electrode leads 240, parallel to the stacking direction of the battery cells 210, and are connected to the electrode leads 240. The joining method may include methods commonly used in the art, such as ultrasonic welding and laser welding, but is not limited thereto.

The terminal bus bar 150' and the bus bar 290 have openings 168, 296 through which the electrode leads 240 pass. The description made with reference to fig. 2 and 3 is equally applied to the terminal bus bar 150'.

Referring to the front view of terminal buss bar 150' shown in fig. 5 and the front view of buss bar 290 shown in fig. 7, a generally O-shape is formed around openings 168, 296. After the electrode lead 240 passes through the openings 168, 296 formed at the center and is bent, the welding of the electrode lead 240 and the bus bars 150', 290 is linearly performed along the long axes of the bus bars 150', 290.

In particular, as shown in fig. 4 and 5, four electrode leads 240 may be coupled to the second metal layer 166 of the coupling portion 160 of one terminal bus 150'. As described above, when four electrode leads 240 are coupled to the coupling part 160 of one terminal bus bar 150', two of the four electrode leads 240 may be stacked on each other, bent leftward through the opening 168 and connected to the left side of the coupling part 160, and the remaining two electrode leads 240 may be bent leftward and connected to the right side of the coupling part 160.

In this case, four electrode leads 240 are respectively provided in four different battery cells 210, and they have the same polarity. For example, the electrode leads 240 connected to the upper right terminal bus bar 150' of fig. 4 are all positive electrode leads. Thus, the upper right terminal bus bar 150' of fig. 4 may be referred to as a positive terminal bus bar. The electrode leads 240 connected to the lower left terminal bus bar 150' of fig. 4 are all negative electrode leads. Thus, the lower left terminal bus bar 150' of fig. 4 may be referred to as a negative terminal bus bar.

Referring to fig. 4 and 7, eight electrode leads 240 may be coupled to one bus bar 290. As described above, when eight electrode leads 240 are coupled to one bus bar 290, among the eight electrode leads 240, two electrode leads 240 are stacked on each other, bent rightward and connected to the left side of the bus bar 290, two electrode leads 240 are stacked on each other, pass through left openings 296 of the two openings 296, bent rightward and connected to the left side of the central portion of the bus bar 290, two electrode leads 240 are stacked on each other, pass through right openings 296 of the two openings 296, bent leftward and connected to the right side of the central portion of the bus bar 290, and the remaining two electrode leads 240 are bent leftward and connected to the right side of the bus bar 290.

In this case, eight electrode leads 240 are respectively provided in eight different battery cells 210, and the four electrode leads 240 on the left side have the same polarity and the four electrode leads 240 on the right side have the opposite polarity. For example, the electrode leads 240 connected to the bus bar 290 are four positive electrode leads and four negative electrode leads.

In particular, a current flow path through the terminal bus bar 150' of the present disclosure will be described in detail with reference to fig. 6. Referring to fig. 6, a current flow path from the outside of the battery module (1000 of fig. 4) into the battery module 1000 passes through the terminal portion 170 of the terminal bus bar 150', the first metal layer 162, the material layer 164, and the second metal layer 166, and then reaches the electrode lead 240. As described above, the material layer 164 is a conductive material under normal conditions and may act as an electrical resistance when the temperature is increased. In abnormal situations, when the temperature is raised above a predetermined level, for example above 300 ℃, the melamine cyanurate in the material layer 164 decomposes to produce N₂And (4) qi. Thus, the resistance of the material layer 164 increases to serve as a resistance layer. In addition, the electrical connection may be broken by volume expansion.

Thus, under normal conditions, the conductivity of the material layer 164 in the terminal bus bar 150' is maintained, and the battery module performance exhibits a similar level to existing bus bars. In an abnormal case, when the temperature is increased above a predetermined level, the resistance of the material layer 164 is increased, thereby preventing the current flowing to the terminal part 170 and the first metal layer 162 from flowing to the material layer 164 and the second metal layer 166. Thus, the current flowing to the electrode lead 240 may be cut off. Thus, when the temperature increases, the material layer 164 acts as a resistor to cut off the current. Thus, even when the secondary battery protection circuit does not operate, the current may be cut off to prevent the current from continuing to flow, for example, to prevent the secondary battery from being charged, thereby improving the safety of the battery module 1000. As described above, the battery module 1000 of the present disclosure modifies the terminal bus bars to automatically cut off current when the temperature rises, thereby implementing an overcharge prevention function of the secondary battery protection circuit and securing safety of the battery module 1000. When the terminal bus bars 150' are configured as described above instead of the bus bars 290, current from an external device or other battery modules may be prevented from flowing to the battery module 1000.

A main cause of a rapid increase in the temperature of the lithium secondary battery, which causes a reduction in safety, is a short-circuit current, and it is very important to ensure the safety of a battery module or a battery pack including battery cells connected to each other when a short-circuit occurs. Since the short-circuit resistance is low, a high short-circuit current flows, and high-temperature heat is generated, and when the battery cell cannot withstand the high-temperature heat, fire may be caught. In some cases, when the short-circuit resistance is very low, a safety result is also obtained, and when the heat generated during the flow of a large current exceeds 660 ℃, the electrode lead is melted and the current is cut off, thereby ensuring safety. When the temperature is less than 660 c, the electrode leads do not melt, current continues to flow, high-temperature heat increases, and fire occurs when the battery cell cannot withstand the high-temperature heat. In contrast, a large current may flow even under normal conditions. In the case such as rapid charging, sudden acceleration of an electric vehicle, or starting, a large current flows in the battery module and high-temperature heat is generated from the electrode leads, and in this normal case, no operation should be performed. To avoid this, it is necessary to cut off the current at a temperature of about 250 ℃ or higher.

In this embodiment, when the battery module 1000 reaches about 300 ℃, gas is generated in the material layer 164 of the terminal bus bar 150' to increase the resistance of the material layer 164. Thus, the cutting mechanism of the material layer 164 does not operate in a normal large current range, and is only allowed to operate above the temperature due to overheating caused by an actually occurring short circuit, thereby preventing ignition and explosion and ensuring safety. In addition, unlike PTC devices or fuses for improved safety, the terminal bus bar does not occupy space in the module and does not reduce energy density.

The battery module 1000 according to the present disclosure has high safety and thus is suitable for power sources of middle-and large-sized devices requiring high-temperature stability, long cycle characteristics, and high rate characteristics. Preferred examples of the middle-and large-sized devices may include, but are not limited to, power tools; electric vehicles including Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs); a two-wheeled electric vehicle including an electric bicycle and an electric motorcycle; an electric golf cart; and an ESS powered and operated by power from the motor.

Terminal buss bar 150' and buss bar 290 may have varying shapes and sizes to form various electrical connection relationships. Additionally, an interconnect board (ICB) assembly in which the terminal bus bars 150 'and the bus bars 290 are assembled on a plastic frame in consideration of wiring relationship is applied to a battery module manufacturing process, rather than using the terminal bus bars 150' and the bus bars 290 alone. The type of the frame and the type of the bus bars combined with the frame are different according to the connection relationship of the battery modules. Thus, those skilled in the art will appreciate that various modifications may be made to the present disclosure.

Fig. 8 is a photographic image of an experimentally fabricated interconnect board (ICB) assembly.

The ICB assembly 300 includes a frame 310, buss bars 290, and terminal buss bars 150'.

The terminal bus bar 150' may be fixed to the frame 310 by the perforation, and thus there is no problem of sliding or layer separation between the volume expandable resin + conductive material + adhesive and the first metal layer 162, and between the volume expandable resin + conductive material + adhesive and the second metal layer 166 when the material layer 164, such as the volume expandable resin + conductive material + adhesive, is horizontally sandwiched between the first metal layer 162 and the second metal layer 166 as proposed by the present disclosure.

As described above, according to the present disclosure, safety may be enhanced by improving the terminal bus bars of the battery module. When the battery module 1000 is manufactured using the terminal bus bar 150' according to the present disclosure instead of the existing bus bar, stability is improved and the existing battery cell manufacturing process may be used, thereby eliminating the need to change processes or adjust mass production processes.

As described above, according to the present disclosure, in a normal case, the conductivity of the material layer 164 in the terminal bus bar 150' is maintained, the battery module performance exhibits a level similar to that of the conventional battery module, and in an abnormal case, when the temperature rises above a predetermined level, the current is cut off, thereby improving the safety of the battery module 1000. Thus, the safety of the battery module 1000, the battery pack including the battery module 1000, and the vehicle including the battery pack may be improved.

Fig. 9 is a diagram illustrating a battery pack according to still another embodiment of the present disclosure.

The battery pack 1200 includes at least two of the above-described battery modules 1000. The intermediate bus bar 1250 connects the terminal portions 170 of the terminal bus bars 150' between the adjacent battery modules 1000. That is, the intermediate bus bar 1250 connects the terminal part 170 of the terminal bus bar 150 'of any one of the at least two battery modules 1000 to the terminal part 170 of the terminal bus bar 150' of the other battery module 1000 in order to connect the battery modules 1000.

The intermediate bus bar 1250 may be a plate shape contacting the terminal portion 170 of the terminal bus bar 150'. In order to make the intermediate bus bar 1250 have a simple shape, i.e., in order to minimize the distance between the adjacent terminal bus bars 150', the positions of the terminal bus bars 150' in the battery module 1000 may be adjusted. For example, the battery module 1000 of fig. 4 is located at the lower portion of fig. 9, and a battery module formed to be mirror-symmetrical with the battery module 1000 of fig. 4 is located at the upper portion of fig. 9.

In the structure of fig. 9, the upper right terminal bus bar 150' is a negative terminal bus bar. The terminal portion 170 of the terminal bus bar 150' has a negative terminal electrically connected to an external terminal for external input. Two terminal bus bars 150' on the left side of the middle portion are a positive terminal bus bar and a negative terminal bus bar from top to bottom of fig. 9. Thus, the intermediate bus bar 1250 connects two terminal bus bars 150' of opposite polarity in series. The lower right terminal bus bar 150' is a positive terminal bus bar. The terminal portion 170 of the terminal bus bar 150' has a positive terminal electrically connected to an external terminal for external input.

The connection between the terminal bus bar 150 'and the intermediate bus bar 1250 may be achieved by bolt-nut fastening using the hole 172 formed in the terminal portion 170 of the terminal bus bar 150'. Accordingly, the intermediate bus bar 1250 may have another hole at the location of the mating hole 172 for bolt-nut fastening.

The battery pack 1200 may further include an assembly case to enclose the battery module 1000. In addition, the battery pack 1200 according to the present disclosure may further include various types of devices, such as a Battery Management System (BMS), a current sensor, and a fuse, in addition to the battery module 1000 and the pack case, to control the charge/discharge of the battery module 1000.

Fig. 10 is a diagram showing a vehicle according to still another embodiment of the present disclosure.

Battery pack 1200 may be disposed in vehicle 1300 as a fuel source for vehicle 1300. For example, the battery pack 1200 may be provided in a vehicle 1300, such as an electric vehicle, a hybrid vehicle, and other applications that use the battery pack 1200 as a fuel source.

Preferably, the vehicle 1300 may be an electric vehicle. The battery pack 1200 may be used as an electric energy source for supplying electric power to the motor 1310 of the electric vehicle to drive the vehicle 1300. In this case, the battery pack 1200 has a high nominal voltage of 100V or more. For a hybrid vehicle, battery pack 1200 is set to 270V.

The battery pack 1200 may be charged or discharged by the inverter 1320 through operation of the motor 1310 and/or the internal combustion engine. Battery pack 1200 may be charged by a regenerative charger coupled to the brakes. The battery pack 1200 may be electrically connected to a motor 1310 of the vehicle 1300 through an inverter 1320.

As described previously, the battery pack 1200 includes a BMS. The BMS evaluates the states of the battery cells in the battery pack 1200 and manages the battery pack 1200 using the evaluated state information. For example, the BMS evaluates and manages state information of the battery pack 1200, including 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. In addition, the BMS controls the charge or discharge of the battery pack 1200 using the state information, and also can evaluate when to replace the battery pack 1200.

An Electronic Control Unit (ECU)1330 is an electronic control device that controls the state of the vehicle 1300. For example, the ECU 1330 determines torque information based on information of the accelerator, brake, and speed, and controls the output of the motor 1310 according to the torque information. In addition, the ECU 1330 sends a control signal to the inverter 1320 to charge or discharge the battery pack 1200 based on the state information of the battery pack 1200, such as the SOC and SOH, received by the BMS. The inverter 1320 allows the battery pack 1200 to be charged or discharged based on a control signal of the ECU 1330. The motor 1310 drives the vehicle 1300 using the electric power of the battery pack 1200 based on control information (e.g., torque information) transmitted from the ECU 1330.

The vehicle 1300 includes the battery pack 1200 according to the present disclosure, and the battery pack 1200 includes the battery module 1000 having improved safety as described previously. Thus, since the stability of the battery pack 1200 is improved, and the battery pack 1200 provides high stability and long-term use, the vehicle 1300 including the battery pack 1200 is safe and easy to operate.

In addition, it is apparent that the battery pack 1200 may be provided in any other devices, apparatuses, and facilities other than the vehicle 1300, such as an Energy Storage System (ESS) and a BMS using a secondary battery.

Since the battery pack 1200 and the apparatus, device, and facility including the battery pack 1200, such as the vehicle 1300, according to the present embodiment include the battery module 1000 described above, the battery pack 1200 and the apparatus, device, and facility including the battery pack 1200, such as the vehicle 1300, having all of the above-described advantages of the battery module 1000 can be realized.

The battery module of fig. 4 was manufactured in a laboratory scale, and the current cutoff effect of the terminal bus bar according to the present disclosure was tested.

The battery cell of the battery module is manufactured by a method of manufacturing a general pouch-type battery cell. The embodiment uses the same bus bar as the terminal bus bar 150' according to the present disclosure, which includes a first metal layer, a material layer, and a second metal layer sequentially stacked, the material layer being conductive under normal conditions but serving as a resistance when temperature increases. The material layer that is conductive under normal conditions but acts as an electrical resistance when the temperature is increased includes a gas generating material, a conductive material, and a binder. The gas generating material is melamine cyanurate, the conductive material is silver (Ag) powder, and the binder is an epoxy resin. The silver content is about 75 to 85 wt%.

Comparative example 1 used a bus bar having a single metal layer. Comparative example 2 used a bus bar having a first metal layer and a second metal layer adhered to each other by silver epoxy resin. The materials of the first metal layer and the second metal layer of the example and the comparative example 2 are the same as those of the bus bar of the comparative example 1. In the examples, comparative examples 1 and 2, the bus bars have the same size.

Fig. 11 is a graph showing the change in resistance and temperature with time of the battery modules used in the experiment. The change in resistance and temperature with time was measured while the overcurrent of 600A was applied to the battery module. Overcurrent was applied using a 1000A charger/discharger and data measurements were made using a data logger. The temperature at the bus bars of the battery module was measured.

Referring to fig. 11, it can be seen that the temperature of comparative example 1 increased almost linearly with time, reached almost 60 ℃ when 30 seconds elapsed, and the resistance gradually increased during this duration while the current continued to flow through the bus bar. In the case of comparative example 2, it can be seen that the temperature rises faster with time than in comparative example 1, and reaches 110 ℃ when 30 seconds have elapsed. The resistance of comparative example 2 gradually increased and increased a little more than that of comparative example 1, but the current continued to flow through the bus bar and no overcurrent cutoff effect was found.

According to the embodiment, the resistance rapidly increases when 8 seconds pass, and thereafter, the measured resistance is 0, whereby it is seen that the resistance measurement cannot be performed due to overcurrent cutoff. As the temperature increases, an increase/decrease in resistance occurs, and the resistance rapidly increases at a specific temperature. Due to these temperature characteristics, the bus bar according to the present disclosure may be referred to as a PTC bus bar. According to the present disclosure, it can be seen that the resistance of the bus bar rapidly increases at a specific time, thereby having an overcurrent cutoff effect. Fig. 12a, 12b, 13a and 13b show external short test results of the battery modules used in the experiments. Fig. 12a and 12b show comparative example 1, and fig. 13a and 13b show an embodiment of the present disclosure. An external short circuit test is performed by connecting a battery module in parallel with a shunt resistor having a known resistance value, measuring a shunt voltage applied to the shunt resistor while a large current flows to cause a short circuit, and calculating a current. During the test, the cell voltage was measured, and the temperatures of the bus bar, the positive electrode, the negative electrode, and the center portion of the cell were measured. Likewise, data measurements are made using a data logger.

Fig. 12a and 13a are graphs of voltage, temperature and current over time, and fig. 12b and 13b are graphs showing the shunt voltage and current at external short circuit.

Fig. 12a and 13a show the result of forcing an external short circuit within 10 minutes after applying current. As time passed, the battery voltage was restored to 3.15V in the case of comparative example 1 of fig. 12a, and to 4.25V in the case of the embodiment of fig. 13 a. In comparative example 1, the unrecovered 1.1V indicates that the current was not completely cut off. Referring to fig. 12b showing the shunt voltage and current at the time of an actual external short circuit, in the case of comparative example 1, a current of 300A or more flows after the external short circuit, and fig. 13b shows that the current is almost 0 after the external short circuit.

In comparing the temperatures of the bus bars, in the case of the embodiment of fig. 13a, it can be seen that the resistance is increased due to a rapid increase in temperature at an early stage, as compared with comparative example 1 of fig. 12a, and as a result, the current is cut off to be difficult to flow. The positive and negative electrode temperatures of comparative example 1 were raised to about 100 ℃, while in the case of the example, the temperature after current cut was maintained almost at room temperature due to the current cut effect of the example.

As can be seen from the above experimental results, the embodiments of the present disclosure have a better current cut-off effect than the comparative examples, and realize a current cut-off function when the temperature actually rises.

Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes may be made within the technical aspects of the present disclosure and the equivalent scope of the appended claims.