KR20200050296A - Battery module with improved safety, battery pack comprising the battery module and vehicle comprising the same - Google Patents

Abstract

Provided are an electrode lead capable of blocking a current when the temperature rises, a battery module with improved safety by including the electrode lead, a battery pack including the battery module, and a vehicle including the battery pack. According to the present invention, the electrode lead is made of a first metal layer and a second metal layer, which is normally conductive but which may be operated as resistance when the temperature rises, wherein the first metal layer and the second metal layer are sequentially stacked. The material layer includes a gas generating material increasing resistance since the gas generating material is decomposed above the certain temperature and the gas generating material generates a gas.

Description

Battery module with improved safety, battery pack including such battery module, and vehicle including such battery pack {Battery module with improved safety, battery pack comprising the battery module and vehicle comprising the same}

The present invention relates to a battery module, and more particularly, to a battery module capable of blocking current flow when the temperature rises. The present invention also relates to a battery pack including such a battery module and an automobile including such a battery pack.

Currently commercially available secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are in the spotlight due to their advantages such as free charging and discharging, a very low self-discharge rate, and high energy density, as they have little memory effect compared to nickel-based secondary batteries.

The lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a unit cell having a structure in which a positive electrode active material is coated on a positive electrode current collector and a negative electrode plate on which a negative electrode active material is coated on a negative electrode collector is disposed with a separator interposed therebetween, and this electrode It is provided with an exterior material for sealingly storing the assembly together with the electrolyte, that is, a battery case. Lithium secondary batteries are classified into can-type secondary batteries in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries in which the electrode assembly is embedded in a pouch of an aluminum laminate sheet, according to the shape of the battery case.

2. Description of the Related Art Secondary batteries are widely used not only in small-sized devices such as portable electronic devices, but also in middle- and large-sized devices such as automobiles and power storage devices (ESS). When used in such a medium-to-large device, a large number of secondary cells are electrically connected to form a battery module or a battery pack to increase capacity and output. Particularly, a pouch type secondary battery is frequently used in such a medium-to-large device due to advantages such as easy lamination and light weight. The pouch type secondary battery has a structure in which an electrode assembly to which an electrode lead is connected is received and sealed together with an electrolyte in a pouch case. A part of the electrode lead is exposed outside the pouch case, and the exposed electrode lead is electrically connected to a device on which the secondary battery is mounted, or used to electrically connect the secondary batteries to each other.

On the other hand, lithium secondary batteries have a risk of explosion when overheated. Particularly, it is applied to electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). In a battery module or a battery pack that is used by connecting battery cells, it is one of the main tasks to secure safety because a very large accident may occur in an explosion.

A typical cause of the rapid increase in the temperature of the lithium secondary battery is when a short circuit current flows. The short circuit current is mainly generated when a short circuit occurs in an electronic device connected to the secondary battery, and when a short circuit occurs in the lithium secondary battery, a rapid electrochemical reaction occurs at the positive electrode and the negative electrode and heat is generated. The heat generated in this way causes the temperature of the battery cell to rise rapidly, causing ignition. In particular, in the case of a battery module or a battery pack including a plurality of battery cells, heat generated from one battery cell is propagated to the surrounding battery cells, which affects other battery cells, which increases with a greater risk.

Conventionally, a PTC device, a fuse, etc. have been proposed as a means to prevent an explosion by blocking current when the temperature inside the secondary battery rises. However, they have a problem that a separate mounting space is required in the battery module or the battery pack.

Securing safety is very important in that the explosion of the battery module or battery pack not only causes damage to the electronic device or the car in which it is employed, but can also lead to a user's safety threat and fire. When the secondary battery overheats, the risk of explosion and / or ignition increases, and rapid combustion or explosion due to overheating may cause personal injury and property damage. Therefore, there is a demand for introducing means for sufficiently securing the safety in the use of the secondary battery.

The problem to be solved by the present invention is to provide an electrode lead capable of blocking current when the temperature rises.

Another problem to be solved by the present invention is to provide a battery module having improved safety by including such an electrode lead, a battery pack including such a battery module, and a vehicle including such a battery pack.

Other objects and advantages of the present invention will be described below, and will be learned by embodiments of the present invention. In addition, the objects and advantages of the present invention can be realized by a combination of configurations and configurations shown in claims.

The electrode lead according to the present invention is composed of a first metal layer / a metal layer / a second metal layer that can be operated as a resistance when the temperature rises, although the first metal layer is stacked one after the other, and the material layer is decomposed at a certain temperature or higher to release gas. It is characterized by including a gas generating material that increases the resistance by generating.

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

The gas-generating material is preferably melamine cyanurate.

The conductive materials are connected and fixed to each other by the adhesive, and when the gas is generated, the conductive materials are disconnected, so that resistance can be increased.

The battery module according to the present invention comprises: a first battery cell having an electrode lead according to the present invention connected to an electrode assembly; And a second battery cell electrically connected to the first battery cell through the electrode lead, wherein a current flow path from the first battery cell to the second battery cell is a first metal layer, material of the electrode lead. It is provided in the order of passing through the layer and the second metal layer, and the current flow path from the second battery cell to the first battery cell is provided in the order of passing through the second metal layer, the material layer and the first metal layer of the electrode lead. Is done.

At this time, the electrode lead of the second battery cell may be composed of the electrode lead according to the present invention.

In the battery module, the current flow path does not flow from the material layer to the second metal layer at a constant temperature at which the gas-generating material of the material layer decomposes or the current does not flow from the second metal layer to the material layer. Is blocked.

The battery module according to the present invention, in a battery module including two or more battery cells, the battery cell is the electrode assembly of which the opposite ends of the electrode leads are respectively connected to both ends are sealed sealed with an electrolyte in the pouch case It is a pouch-type secondary battery having a structure, and the other end of the electrode lead is exposed to the outside of the pouch case, and the electrode lead and the bus are used to electrically connect adjacent first battery cells and second battery cells. A bar is connected, and at least one of the electrode leads is made of an electrode lead according to the present invention, that is, a first metal layer / sequentially stacked one after the other, which is conductive at normal times, but is made of a material layer / second metal layer that can act as a resistance when the temperature rises. Is the material layer decomposed at a certain temperature or higher to generate gas to increase resistance? It may also be generated that contains the material.

In this case, the first battery cell and the second battery cell may be connected in series through the bus bar.

The first battery cell and the second battery cell are alternately stacked such that each electrode lead has opposite polarities, and the other end of the electrode lead of the first battery cell and the other end of the electrode lead of the second battery cell It is bent toward each other along the stacking direction, and the bus bars may be placed in parallel with the stacking direction between the bent portions of each electrode lead to be connected between each electrode lead.

And, the present invention, the battery pack, at least one battery module according to the present invention; And it provides a battery pack comprising a pack case for packaging the at least one battery module.

In addition, the present invention provides an automobile, comprising at least one battery pack according to the invention.

According to the present invention, by changing the electrode lead of the adjacent battery cells to be able to increase the resistance when the temperature rises, when overheating when using a battery module connected to these battery cells, the current flow through the electrode lead is blocked Do it. As a configuration for increasing the resistance of the electrode lead, a material layer containing a gas generating material is included in the electrode lead, so that the current flow through the electrode lead is blocked when the temperature at which the gas generating material is decomposed is blocked. Therefore, 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, thereby increasing the safety of the battery module. As described above, the battery module of the present invention implements a means for automatically blocking the flow of current when the temperature rises by improving the electrode lead, and thus, it is possible to secure the safety of the battery module in addition to the overcharge prevention function of the secondary battery protection circuit. There is also.

According to the present invention, it is possible to provide a battery module using an electrode lead according to the present invention when configuring an electrical connection path by connecting in series between adjacent battery cells. When an event occurs, such as a situation where an abnormal temperature is reached, the resistance increases as the gas generating material contained in the material layer in the electrode lead decomposes. As a result, the safety of the battery module can be secured because the adjacent battery cells are disconnected from the electrical connection and the current flow is blocked.

According to the present invention, safety is secured by improving the electrode leads of the battery module. The advantage of being able to secure the safety of the battery module is a relatively simple method of manufacturing a battery cell using the electrode lead according to the present invention instead of the existing electrode lead. Since the existing battery cell manufacturing process is used as it is except for the replacement of the electrode leads, no process change or adjustment to the mass production process is necessary.

As described above, according to the present invention, under normal circumstances, the conductivity of the material layer in the electrode leads is maintained to express battery cell performance similar to that of the existing electrode leads, while blocking the current flow when rising to a certain temperature or higher due to a non-ideal condition. Module safety can be improved. 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.

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the detailed description of the invention described below, and thus the present invention is described in such drawings. It should not be interpreted as being limited to.
1 is an electrode lead according to an embodiment of the present invention.
2 and 3 show a part of a battery module manufactured by connecting a battery cell including the electrode lead of FIG. 1 to another battery cell.
4 schematically illustrates a battery module according to another embodiment of the present invention.
5 is a top view of a pouch-type secondary battery as a unit battery cell included in the battery module of FIG. 4.
FIG. 6 schematically shows an embodiment in which the battery modules of FIG. 4 can be connected between two adjacent battery cells via a bus bar.
7 is a view for explaining a battery pack according to another embodiment of the present invention.
8 is a view for explaining a vehicle according to another embodiment of the present invention.

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 ordinary or lexical meanings, and the inventor appropriately explains the concept of terms in order to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Therefore, the embodiments shown in the embodiments and the drawings described in this specification are only the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. It should be understood that there may be equivalents and variations. The same reference numbers in the drawings indicate the same elements.

In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery collectively refers to 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.

On the other hand, even though the name of the secondary battery changes depending on the type of electrolyte or separator used in the lithium secondary battery, the type of the battery case used to pack the secondary battery, and the structure of the inside or outside of the lithium secondary battery, lithium ions are operating ions. All secondary batteries used as should be interpreted as being included in the category of the lithium secondary battery.

The present invention can also be applied to secondary batteries other than lithium secondary batteries. Therefore, even if the operating ions are not lithium ions, any secondary battery to which the technical idea of the present invention can be applied should be interpreted to be included in the scope of the present invention regardless of the type.

1 shows an electrode lead according to an embodiment of the present invention.

Referring to FIG. 1, the electrode lead 40 is composed of a first metal layer 42 / a metal layer 44 / a second metal layer 46 that can be operated as a resistance when the temperature rises, although it is usually conductive. .

The electrode lead 40 is a thin plate material having a smaller thickness T than the length L and width W. One end in the length (L) direction is connected to the electrode assembly and the other end will be exposed outside the battery case.

The first metal layer 42, the material layer 44, and the second metal layer 46 are stacked along the thickness T direction.

The first metal layer 42 and the second metal layer 46 may include metal having good electrical conductivity. For example, it may include at least one of aluminum, copper, nickel, and SUS. The first metal layer 42 and the second metal layer 46 may use various materials that can be used as existing electrode lead materials. The first metal layer 42 and the second metal layer 46 may be made of the same material as the electrode plate to which the electrode lead 40 is attached. For example, when an anode (+) lead attached to an anode plate having an aluminum material as a main component is to be manufactured, aluminum may be included as the main component. In addition, when a negative electrode (-) lead attached to a negative electrode plate having a copper material as a main component is to be manufactured, copper may be included as a main component.

The first metal layer 42 and the second metal layer 46 may be of the same type or different types. For example, in the case of manufacturing the anode lead, the first metal layer 42 and the second metal layer 46 may include aluminum. In the case of manufacturing the cathode lead, the first metal layer 42 and the second metal layer 46 may include copper. The first metal layer 42 may be made of aluminum, and the second metal layer 46 may be made of copper. In such a case, when the electrode lead 40 is attached to the positive electrode plate, the first metal layer 42 is directed toward the positive electrode plate. When the electrode lead 40 is attached to the negative electrode plate, the second metal layer 46 is directed toward the negative electrode plate. Thus, if the first metal layer 42 and the second metal layer 46 are of different types, the surfaces attached to the electrode plate are the first metal layer 42 or the second metal layer 42 without having to separately manufacture the positive electrode lead and the negative electrode lead. The process can be carried out as easily as changing to the metal layer 46.

The material layer 44 sandwiched between the first metal layer 42 and the second metal layer 46 includes a gas generating material that decomposes at a predetermined temperature or more to generate gas, thereby increasing resistance. Preferably, the material layer 44 includes such a gas generating material and a conductive material and an adhesive. The conductive materials are connected and fixed to each other by an adhesive, and when the gas is generated in the gas generating material, the connection of the conductive material is released, so that resistance can be increased.

It is preferable that the gas generating material is Melamine Cyanurate. Melamine cyanurate is a material used as a nitrogen-phosphorus flame retardant component in which nitrogen and phosphorus are combined, and can be obtained as a raw material having an average particle size of several tens of um through various manufacturers.

Melamine cyanurate, commonly used for flame retardant applications, undergoes endothermic decomposition with temperatures in excess of about 300 ° C. Melamine cyanurate breaks down into melamine and cyanuric acid. The vaporized melamine releases inert nitrogen gas. Degradation temperature can be controlled by adjusting the molecular weight of melamine cyanurate. The structural formula of melamine cyanurate is as follows.

[constitutional formula]

The conductive material is not particularly limited as long as it has conductivity, 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, and nickel powders; 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.

The adhesive is a component that assists the bonding of the gas generating material and the conductive material and the like to the first metal layer 42 and the second metal layer 46. Examples of such adhesives include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, and various copolymers.

Melamine cyanurate is decomposed in the material layer 44 inserted between the first metal layer 42 and the second metal layer 46 when the temperature rises to a predetermined temperature or higher due to a non-ideal situation, for example, when the temperature rises to 300 ° C or higher. N ₂ gas is generated. Accordingly, the material layer 44 increases in resistance to operate as a resistance layer.

The manufacturing method of the electrode lead 40 may be performed as follows.

First, each plate material that can be the first metal layer 42 and the second metal layer 46 is prepared. These may be roll-to-roll rolled while rolling the appropriate metal material. These are placed upside down, unwound, rewinded, and put or apply a paste or slurry mixed with a gas-generating material and a conductive material and an adhesive, which can become a material layer 44, and press it from the top and bottom. It is possible to obtain a material in which a material layer 44 is sandwiched between plate materials. In the subsequent process, the material may be additionally rolled or made into a final thickness (T), and then cut by a desired width (W) and length (L) to be used as the electrode lead (40).

The thickness T of the electrode lead 40 may be the same as the thickness of the existing electrode lead. The first metal layer 42 and the second metal layer 46 can also be made the same as the material of the existing electrode lead. The normal electrical conductivity of the material layer 44 may be made similar to the electrical conductivity of the existing electrode lead by making the conductive material in the material layer 44 the same or higher than the existing electrode lead material.

Therefore, under normal circumstances, the conductivity of the material layer 44 in the electrode lead 40 is maintained, so that battery cell performance similar to that of the existing electrode lead can be exhibited. When the temperature rises above a certain level due to a non-ideal situation, the resistance of the material layer 44 increases, so that the current flow is blocked. Accordingly, when the temperature rises, since the material layer 44 acts as a resistor to block current, it is possible to improve safety of a battery module including a battery cell manufactured by including the same.

2 and 3 show a part of a battery module manufactured by connecting a battery cell including the electrode lead of FIG. 1 to another battery cell. For example, it shows a state in which two pouch-type battery cells are connected in series.

2 and 3, the pouch-shaped battery cell 10 includes an electrode lead 40 drawn out of the pouch case 30. The electrode lead 40 is divided into an anode (+) lead and a cathode (-) lead according to electrical polarity, and is electrically connected to the electrode assembly 20 sealed in the pouch case 30. That is, the positive electrode lead is electrically connected to the positive electrode plate of the electrode assembly 20, and the negative electrode lead is electrically connected to the negative electrode plate of the electrode assembly 20. In this embodiment, although both the positive electrode lead and the negative electrode lead have been exemplified with the electrode lead 40 according to the present invention, only one of the positive electrode lead and the negative electrode lead may be the electrode lead 40 according to the present invention.

There may be various ways in which the battery cells 10 are connected in series in the battery module 100, and FIG. 2 shows the electrode leads bent using the connection bar 50 after bending the electrode leads 40. It shows a method of welding between the electrode lead 40 of the battery cell 10 and the electrode lead 40 'of the other battery cell 10' by welding to 40), and FIG. 3 shows a bent electrode lead 40 , 40 ') by overlapping each other and welding directly. At this time, the electrode lead 40 'of the other battery cell 10' may be composed of the electrode lead 40 according to the present invention.

As described above, in the present invention, by configuring the electrode lead 40 whose resistance increases when the temperature rises between adjacent battery cells 10 and 10 ', the material in the electrode lead 40 is overheated when the battery module 100 is used. When the gas generating material of the layer (44 in FIG. 1) reaches a decomposition temperature, the current flow through the electrode lead 40 is blocked. 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, thereby improving the safety of the battery module 100. As described above, the battery module 100 of the present invention implements a means to automatically cut off the flow of current when the temperature rises by improving the electrode lead 40, so that the battery module 100 is doubled with the function of preventing overcharge of the secondary battery protection circuit ) Also has the effect of ensuring safety.

According to the present invention, it is possible to provide the battery module 100 using the electrode lead 40 according to the present invention when configuring the electrical connection path by connecting in series between adjacent battery cells 10 and 10 ′. When an event, such as a situation of reaching an abnormal temperature, occurs, the gas generating material contained in the material layer 44 in the electrode lead 40 decomposes, thereby increasing resistance. As a result, the safety of the battery module 100 can be secured because the adjacent battery cells 10 and 10 ′ are disconnected from the electrical connection and current flow is blocked.

As described above, according to the present invention, safety is secured through improvement of the electrode lead 40 of the battery module 100. The battery cell 10 may be manufactured by using the electrode lead 40 according to the present invention instead of the existing electrode lead, and since it uses the existing battery cell manufacturing process as it is, there is no need to adjust the process or adjust the mass production process. to be.

As described above, according to the present invention, under normal circumstances, the conductivity of the material layer 44 in the electrode leads 40 is maintained to express battery cell performance similar to that of the existing electrode leads, but when the temperature rises to a predetermined temperature or higher due to a non-ideal situation, By blocking the current flow, it is possible to improve the safety of the battery module 100. Therefore, it is possible to improve the safety of the battery module 100, a battery pack including the same, and a vehicle including the battery pack.

4 schematically illustrates a battery module according to another embodiment of the present invention. 5 is a top view of a pouch-type battery cell as a unit battery cell included in the battery module of FIG. 4.

The battery module 1000 of FIG. 4 illustrates an example in which a plurality of battery cells 200a, 200b, 200c, ... are electrically connected in series. Each of the plurality of battery cells 200a, 200b, 200c, ... is a pouch-type battery cell 200 as illustrated in FIG. 5, and may have the same structure.

Referring to FIG. 5, the pouch type battery cell 200 is sealed by receiving the electrode assembly 210 and the electrolyte together in the pouch case 230. The pouch case 230 may be configured to include a metal layer, an outer resin layer, and an inner resin layer to seal the electrode assembly 210 and the electrolyte solution stored therein and protect them from the outside.

One end of the positive electrode lead 240 and the negative electrode lead 250 formed in a plate shape is connected to both ends of the electrode assembly 210, and each other end is exposed outside the pouch case 230. One end of the positive electrode lead 240 is electrically connected to the positive electrode plate of the electrode assembly 210, and one end of the negative electrode lead 250 is electrically connected to the negative electrode plate of the electrode assembly 210. The other ends of the electrode leads 240 and 250 exposed outside the pouch case 230 are used to electrically connect a plurality of pouch-type secondary batteries to each other as shown in FIG. 4.

A lead film 260 is interposed between the pouch case 230 and the electrode leads 240 and 250. The lead film 260 is provided to further improve the adhesion between the pouch case 230 and the electrode leads 240 and 250. The lead film 260 not only prevents a short circuit from occurring between the electrode leads 240 and 250 and the metal layer of the pouch case 230, but also improves the sealing property of the pouch case 230. When heat-sealing the electrode leads 240 and 250 made of metal and the pouch case 230 made of polymer, the contact resistance may be slightly large and the surface adhesion may be deteriorated. However, as in the above embodiment, when the lead film 260 is provided, such a decrease in adhesion may be prevented. In addition, the lead film 260 is preferably an insulating material that can block the application of current from the electrode leads (240, 250) to the pouch case (230). The lead film 260 is made of a film having insulation and heat fusion properties. The lead film 260 may be made of any one or more material layers (single film or multiple films) selected from, for example, polyimide (PI), polypropylene, polyethylene, and polyethylene terephthalate (PET). .

The electrode assembly 210 is a collection of unit cells having a structure in which a positive electrode plate and a negative electrode plate are disposed with a separator therebetween. The unit cell can be simply stacked, stacked and folded, or made of an electrode assembly in the form of a jelly roll. Since the method of manufacturing the electrode assembly in various types is widely known, detailed description will be omitted. For example, the electrode assembly 210 may be formed by stacking a negative electrode plate, a separator, and a positive electrode plate. The electrode assembly 210 may be a monocell made of a negative electrode plate / separator / anode plate or a bicell shape made of a negative electrode plate / separator / anode plate / separator / cathode plate or a positive electrode plate / separator / cathode plate / separator / anode plate. In this embodiment, the positive electrode lead 240 and the negative electrode lead 250 are exemplified as bi-directional batteries, which are drawn out in opposite directions from the pouch case 230, but both the positive electrode lead 240 and the negative electrode lead 250 It does not exclude the unidirectional battery aspect that is withdrawn from the pouch case 230 in one direction.

At least one of the positive electrode lead 240 and the negative electrode lead 250 is configured as the electrode lead 40 of the present invention. The electrode lead 40 can be followed as described with reference to FIG. 1.

4 and 5 together, the battery cells 200a, 200b have electrode leads protruding from both ends thereof, and the electrode leads 240a of the battery cell 200a, for example, are opposite polarities. The battery cells 200b are stacked so as to lie side by side with the negative lead 250b. That is, several battery cells are alternately stacked so that electrode leads placed side by side are of opposite polarity to each other. There may be various ways in which the battery cells 200a, 200b, 200c, ... are connected in series, and in FIG. 4, the other end of the electrode leads 240a, 250b is bent to the left or right in a bent form to form a flat contact surface. It shows a configuration that is connected to each other by welding by overlapping them after providing them.

In FIG. 4, 11 battery cells are included in total. The electrode leads of each battery cell are vertically bent, so that the electrode bends of other neighboring battery cells and the vertically bent portions overlap each other to form a lead connection portion 245. More specifically, the inner electrode leads excluding the electrode leads located at the outermost side of one side of the stacked battery cells 200a, 200b, 200c,… are bent and overlapped with each other, and then the bent electrode lead parts are electrically connected. . On the other side of the stacked battery cells 200a, 200b, 200c, ..., all of the electrode leads are bent to overlap each other, and then welded to electrically connect the bent electrode lead parts.

In Fig. 4, the battery cells 200a, 200b, 200c, ... are erected and stacked in the vertical direction. When bending the electrode lead, either electrode lead in the battery cell is vertically bent in the right (or outside the battery module) direction and the other electrode lead is vertically bent in the left (or inside the battery module) direction. Accordingly, the lead connecting portion 245 to be coupled has a 'c' shape, so that electrode leads of different polarities are bent and overlapped. Then, the lead connecting portions 245 are arranged side by side along the horizontal direction. This process can be performed in the reverse process, for example, by bending the electrode leads first, stacking the battery cells in a bent state, and then welding the corresponding portion.

Meanwhile, FIG. 4 illustrates a method of directly connecting the electrode leads by overlapping them, but of course, an indirect connection method using a connection bar is also possible as described with reference to FIG. 2. For example, it is natural that the present invention can also be applied to a case where a battery module is constructed by welding a bus bar together to an electrode lead or when a battery module is constructed by welding an electrode lead and an external circuit. In the following embodiment, a case in which a battery module is configured by welding a bus bar will be described in more detail.

FIG. 6 schematically illustrates an aspect in which the battery modules of FIG. 4 can be connected between two adjacent battery cells via a bus bar.

Referring to FIGS. 4 and 6 together, when each of two adjacent battery cells in the battery module 1000 is referred to as a first battery cell 200a and a second battery cell 200b, the first battery cell 200a and the bus bar 300 are connected, and the bus bar 300 and the second battery cell 200b are connected. Specifically, one side of the bus bar 300 is connected to the positive lead 240a of the first battery cell 200a, and the other side of the bus bar 300 is connected to the negative lead 250b of the second battery cell 200b. connected. In this way, the positive electrode lead 240a of the first battery cell 200a and the negative electrode lead 250b of the second battery cell 200b are connected to each other via the bus bar 300, so that the first and second battery cells (200a, 200b) are electrically and electrically connected in series. The connection may be made by a method conventionally made in the art, and may be combined and connected by, for example, ultrasonic welding, but is not limited thereto.

In this embodiment, the other end of the positive electrode lead 240a of the first battery cell 200a and the other end of the negative electrode lead 250b of the second battery cell 200b are the first and second battery cells 200a, 200b. It is bent toward each other along the stacking direction of, and the bus bar 300 is placed in parallel with the stacking direction between the bent portions of each electrode lead 240a, 250b so that each electrode lead 240a, 250b is connected. It is.

In this embodiment, the positive lead 240a of the first battery cell 200a is configured as the electrode lead 40 of the present invention. The anode lead 240a includes a first metal layer 242a, a material layer 244a, and a second metal layer 246a. Each of the first metal layer 242a, the material layer 244a, and the second metal layer 246a Corresponding to the first metal layer 42, the material layer 44, and the second metal layer 46 of the electrode lead 40, respectively.

Therefore, the material layer 244a includes a gas generating material that decomposes at a predetermined temperature or higher to increase resistance by generating gas, and in normal circumstances, the conductivity of the material layer 244a in the positive electrode lead 240a is maintained to maintain the existing electrode. The battery cell performance similar to that of a lead can be exhibited, but when the temperature rises above a certain level due to a non-ideal situation, the resistance of the material layer 244a increases, so that it can block current flow. Accordingly, when the temperature rises, since the material layer 244a acts as a resistor to block current, it is possible to improve the safety of the battery module 1000 including the first battery cell 200a.

Looking more specifically, the first battery cell 200a and the second battery cell 200b are electrically connected through the electrode lead, particularly the positive lead 240a and the negative lead 250b, and the bus bar 300 is connected. Connected by mediation. As shown in detail in FIG. 6, one end of the positive electrode lead 240a of the first battery cell 200a is electrically connected to the positive electrode plate 215 of the electrode assembly 210, particularly the first metal layer 242a. It is connected to directly contact 215. One end of the positive electrode lead 250b of the second battery cell 200b is electrically connected to the negative electrode plate 217 of the electrode assembly 210.

Here, the current flow path from the first battery cell 200a to the second battery cell 200b includes a positive electrode lead 240a and a bus bar from the positive electrode plate 215 of the electrode assembly 210 of the first battery cell 200a. 300), the negative electrode lead 250b of the second battery cell 200b, and the negative electrode plate 217 of the electrode assembly 210 of the second battery cell 200b. And, the current flow path from the first battery cell 200a to the second battery cell 200b is a sequence through the first metal layer 242a, the material layer 244a and the second metal layer 246a of the positive electrode lead 240a. Is prepared. And, the current flow path from the second battery cell 200b to the first battery cell 200a, on the contrary, is the second metal layer 246a, the material layer 244a, and the first metal layer 242a of the positive electrode lead 240a. ).

At a constant temperature at which the gas generating material of the material layer 244a decomposes, no current flows from the material layer 244a to the second metal layer 246a. Conversely, no current flows from the second metal layer 246a to the material layer 244a. Therefore, the current flow path from the first battery cell 200a to the second battery cell 200b at a constant temperature at which the gas generating material of the material layer 244a is decomposed, and the first battery cell from the second battery cell 200b The current flow path to 200a is blocked.

As described above, the first battery cell 200a and the second battery cell 200b in the electrical connection state through the bus bar 300 are materials in the positive electrode lead 240a of the first battery cell 200a when the temperature rises Gas is generated in layer 244a, thereby breaking the electrical connection.

A typical cause of deteriorating safety due to a rapid rise in the temperature of a lithium secondary battery is that a short circuit current is generated, and it is very important to ensure 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, resulting in large heat, and ignition occurs when the battery cell cannot withstand it. When the short-circuit resistance is very low, some safe results are obtained. This is when the heat generated during high current flow exceeds 660 ° C and the electrode lead is melted, thereby interrupting the current flow and securing safety. When the generated temperature is lower than this, the electrode lead does not melt, and current flows continuously, causing high heat to accumulate and igniting due to the battery cell not being able to withstand. On the other hand, even under normal circumstances, high current may flow. In an electric vehicle, a large current flows through the battery module in a situation such as rapid charging, rapid acceleration, or starting, and thus, a high temperature is generated in the electrode lead. In order to prevent this, it is necessary to block the flow of current at a temperature of about 250 ° C or higher.

In the present invention, the electrical connection between the first battery cell 200a and the second battery cell 200b causes gas to be generated in the material layer 244a when the battery module 1000 reaches about 300 ° C. (244a) Let resistance increase. Accordingly, it does not operate in the normal high current range, and operates only when an actual short circuit occurs and is overheated to a higher temperature, thereby securing safety against fire or explosion. In addition, it has the advantage of not reducing the energy density because it does not take up space in the module, such as other safety improvement devices such as PTC devices or fuses.

Since the battery module according to the present invention has excellent safety, it is also suitable for use as a power source for medium to large-sized devices that require high temperature stability, long cycle characteristics, and high rate characteristics. A preferred example of the medium-to-large-sized device includes a power tool that is powered by an electric motor and moves; Electric vehicles including EV, HEV, PHEV, etc .; Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; And ESS, but are not limited thereto.

7 is a view for explaining a battery pack according to an embodiment of the present invention. 8 is a view for explaining a vehicle according to an embodiment of the present invention.

7 and 8, the battery pack 1200 may include at least one battery module according to the previous embodiment, for example, the battery module 1000 of the second embodiment and a pack case 1210 for packaging it. . In addition, the battery pack 1200 according to the present invention, various devices for controlling charging and discharging of the battery module 1000 in addition to the battery module 1000 and the pack case 1210, such as BMS (Battery Management System), current Sensors, fuses, and the like may be further included.

The battery pack 1200 is a fuel source of the vehicle 1300 and may be provided in 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 methods that can 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 driving the vehicle 1300 by providing driving force to the motor 1310 of the electric vehicle. In this case, the battery pack 1200 has a high nominal voltage of 100 V or more. For hybrid vehicles, it is set to 270V.

The battery pack 1200 may be charged or discharged by the inverter 1320 according to the driving of the motor 1310 and / or an internal combustion engine. The battery pack 1200 may be charged by a regenerative charging device combined with a break. The battery pack 1200 may be electrically connected to the motor 1310 of the vehicle 1300 through the inverter 1320.

As described above, the battery pack 1200 also includes a BMS. The BMS estimates the state of the battery cells in the battery pack 1200 and manages the battery pack 1200 using the estimated state information. For example, battery pack 1200 state information such as state of charge (SOC), state of health (SOH), maximum input / output power allowance, and output voltage of the battery pack 1200 is estimated and managed. In addition, the charging or discharging of the battery pack 1200 is controlled by using the state information, and it is also possible to estimate the replacement time of the battery pack 1200.

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 speed, and the output of the motor 1310 is controlled to match the torque information. Further, 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 uses the electric energy of the battery pack 1200 to drive the vehicle 1300 based on control information (eg, torque information) transmitted from the ECU 1330.

The vehicle 1300 includes a battery pack 1200 according to the present invention, and the battery pack 1200 includes a battery module 1000 with improved safety as described above. Therefore, 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 same is safe and easy to operate.

In addition, the battery pack 1200 may be provided in other devices, apparatus and equipment, such as an ESS BMS using a secondary battery in addition to the vehicle 1300, of course.

As described above, a device, apparatus, and equipment provided with the battery pack 1200, such as the battery pack 1200 and the vehicle 1300 according to the present embodiment includes the above-described battery module 1000, and the above-described battery module It is possible to implement devices, apparatus and equipment such as a battery pack 1200 having all of the advantages due to 1000 and a vehicle 1300 equipped with the battery pack 1200.

Although the present invention has been described above by way of limited examples and drawings, the present invention is not limited by this, and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

10, 10 ', 200, 200a, 200b, 200c: battery cell
20, 210: electrode assembly
30, 230: pouch case
40, 40 ', 240, 240a, 250, 250b: electrode lead
42, 242a: first metal layer
44, 244a: material layer
46, 246a: second metal layer
50: connection bar
100, 1000: battery module
215: positive electrode plate
217: negative plate
240: anode lead
245: lead connection
300: bus bar
1200: battery pack
1210: pack case
1300: car
1310: motor
1320: inverter
1330: ECU

Claims (13)

The stacked first metal layer / constantly consists of a material layer / second metal layer that is electrically conductive but can act as a resistance when the temperature rises,
The material layer is decomposed at a certain temperature or more, the electrode lead, characterized in that it comprises a gas generating material to increase the resistance by generating gas. The electrode lead according to claim 1, wherein the material layer contains the gas generating material, a conductive material, and an adhesive. The electrode lead according to claim 1, wherein the gas generating material is melamine cyanurate. According to claim 2,
An electrode lead, characterized in that 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. A first battery cell connecting the electrode lead of claim 1 to an electrode assembly; And
A battery module including a second battery cell electrically connected to the first battery cell through the electrode lead,
The current flow path from the first battery cell to the second battery cell is provided in the order of passing through the first metal layer, the material layer and the second metal layer of the electrode lead,
A battery module, characterized in that the current flow path from the second battery cell to the first battery cell is provided in order of passing through the second metal layer, the material layer and the first metal layer of the electrode lead. The current flow path of claim 5, wherein no current flows from the material layer to the second metal layer at a constant temperature at which the gas-generating material of the material layer decomposes, or no current flows from the second metal layer to the material layer. Battery module characterized in that it is cut off. The battery module according to claim 5, wherein the gas generating material of the material layer is melamine cyanurate. A battery module comprising two or more battery cells,
The battery cell has a structure in which an electrode assembly having one end of an electrode lead of opposite polarity connected to both ends is sealed with an electrolyte in a pouch case, and the other end of the electrode lead is exposed to the outside of the pouch case. It is a pouch type secondary battery,
The electrode leads and the bus bar are connected to electrically connect adjacent first battery cells and second battery cells,
At least one of the electrode leads is made of a first metal layer / material layer / second metal layer that is conductive in normal operation but can act as a resistance when the temperature increases.
The material layer is decomposed at a predetermined temperature or more, and a battery module comprising a gas generating material that increases the resistance by generating gas. The battery module according to claim 8, wherein the first battery cell and the second battery cell are connected in series through the bus bar. The method of claim 8, wherein the first battery cell and the second battery cell are stacked alternately so that each electrode lead is opposite to each other, and the other end of the electrode lead of the first battery cell and the second battery cell. The other end of the electrode lead is bent toward each other along the stacking direction, and the battery module, characterized in that the bus bar is placed in parallel with the stacking direction between each electrode lead to be connected between each electrode lead. The battery module according to claim 8, wherein the gas generating material is melamine cyanurate. At least one battery module according to any one of claims 6 to 11; And
A battery pack comprising a pack case for packaging the at least one battery module. A vehicle comprising at least one battery pack according to claim 12.

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