WO2019103310A1 - Battery module having improved safety, battery pack including battery module, and vehicle including battery pack - Google Patents

Abstract

A safety member is provided to a lead connecting part of a battery module so as to improve the safety of the battery module during overcharging. The battery module according to the present invention includes two or more battery cells and comprises a current breaking battery cell, which electrically connects a first battery cell and a second battery cell adjacent to each other and releases the electrical connection thereof by rupturing during overcharging.

Description

A battery module including such a battery module, and an automobile including such a battery pack

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery module, and more particularly, to a battery module capable of blocking current flow during overcharging. The present invention also relates to a battery pack including such a battery module and a vehicle including such a battery pack. This application claims priority to Korean Patent Application No. 10-2017-0157433 filed on November 23, 2017 and Korean Patent Application No. 10-2018-0099235 filed on August 24, 2018 , The disclosure of which is incorporated herein by reference in its entirety.

The secondary rechargeable batteries are nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have almost no memory effect compared to nickel- The self-discharge rate is very low and the energy density is high.

These lithium secondary batteries mainly use a lithium-based oxide and a carbonaceous material as a cathode active material and an anode active material, respectively. The lithium secondary battery includes an electrode assembly in which unit cells having a structure in which a positive electrode plate in which a positive electrode active material is coated on a positive electrode collector and a negative electrode plate in which a negative electrode active material is coated on a negative electrode collector are disposed with a separator interposed therebetween, A battery case for sealingly storing the assembly together with the electrolytic solution.

The lithium secondary battery is classified into a can-type secondary battery in which an electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which an electrode assembly is embedded in a pouch of an aluminum laminate sheet, depending on the shape of the battery case.

In recent years, secondary batteries have been widely used not only in small-sized devices such as portable electronic devices, but also in medium- to large-sized devices such as automobiles and electric power storage devices (ESS). When used in such a medium to large-sized apparatus, a large number of secondary cells are electrically connected to increase the capacity and the output, thereby constituting a battery module or a battery pack. Particularly, the pouch-type secondary battery is widely used because of its advantages such as easy lamination and light weight in such a middle- or large-sized apparatus.

The pouch type secondary battery has a structure in which an electrode assembly, to which an electrode lead is connected, is housed and sealed in an electrolyte solution in a pouch case. A part of the electrode lead is exposed to the outside of the pouch case and the exposed electrode lead is electrically connected to the device in which the secondary battery is mounted or used to electrically connect the secondary batteries.

1 and 2 are views showing a state in which, for example, two pouch type secondary batteries are connected in series in a conventional battery module.

As shown in the figure, the pouch type secondary battery 10 includes an electrode lead 40 drawn out from the pouch case 30. The electrode lead 40 is electrically connected to the electrode assembly 20 which is divided into a positive lead and a negative lead according to electrical polarity and is 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.

1 is a perspective view of a pouch type secondary battery 10 according to an embodiment of the present invention. Referring to FIG. 1, after the electrode lead 40 is bent, the electrode lead 40 is welded And FIG. 2 illustrates a method of welding the electrode leads 40, which are folded over each other, and connecting the electrode leads 40. FIG. In the indirect connection method of FIG. 1 or the direct connection method of FIG. 2, a portion where the electrode leads 40 are connected to each other is referred to as a lead connecting portion A. A plurality of pouch- And they are connected to each other through the connecting portion A.

On the other hand, it is necessary to protect the secondary battery from an abnormal situation such as overcharging, overdischarging, overheating, overcurrent, etc., and it is general that the secondary battery protection circuit is also implemented in the battery module or the battery pack. Especially, technologies such as high capacity active material, thin separator and high voltage drive are developed and applied for high energy density and low cost of rechargeable batteries. Overcharging is a problem and overcoming of ignition and explosion problem in overcharging condition Is required. Further, since the lithium secondary battery uses an organic solvent which is flammable, it is necessary to secure safety when an abnormal state is caused by overcharging or the like.

However, the conventional lead connecting portion A has no function other than the path of the current flow. There is no relation to the function of securing the safety of the battery module having such a connection structure. As described above, since the lead connecting portion A does not have a safety member in the over-charging state, there is a problem in that safety is extremely weak if the over-charging preventing function of the secondary battery protecting circuit does not operate normally.

In recent years, safety issues have become the biggest social issue in the field of secondary batteries. The explosion of the battery module or the battery pack is recognized as an important issue in that the safety of the electronic device or the automobile is not only deteriorated but also can be connected to a safety threat of a user and a fire. When the secondary battery is overcharged, the risk of explosion and / or ignition increases, and sudden combustion or explosion due to overcharging may damage human life and property. Therefore, there is a demand for introducing a device for securing sufficient safety in use of the secondary battery.

A problem to be solved by the present invention is to provide a battery module with improved safety by providing a safety member at the time of overcharging in a lead connecting portion of the battery module, a battery pack including such a battery module, and an automobile including such a battery pack.

Other objects and advantages of the present invention will be described hereinafter and will be understood by the embodiments of the present invention. Further, objects and advantages of the present invention can be realized by a combination of the constitution and the constitution shown in the claims.

A battery module according to the present invention is a battery module including two or more battery cells, which electrically connects between a first battery cell and a second battery cell that are adjacent to each other, and ruptures upon overcharging, And a current cut-off battery cell.

In the present invention, each of the first battery cell, the second battery cell, and the current intercepting battery cell has a structure in which an electrode assembly having opposite ends of electrode leads of opposite polarity are connected to both ends, And the other end of the electrode lead is exposed to the outside of the pouch case.

In the present invention, the first battery cell and the current cutoff battery cell may be connected in series, and the current cutoff battery cell and the second battery cell may be connected in series.

The electrode lead of the first battery cell and the electrode lead of the second battery cell may be connected to each other through the electrode lead of the current blocking battery cell.

The first battery cell and the second battery cell are alternately stacked such that the respective electrode leads are opposite in polarity, 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 are It is preferable that the current blocking battery cells are folded toward each other along the stacking direction and the current blocking battery cells are placed between the bent portions of the respective electrode leads so as to be parallel to the stacking direction and connected between the respective electrode leads.

Wherein the current blocking battery cell is smaller than the first battery cell and the second battery cell so as to be positioned between the bent portions of the respective electrode leads without affecting the interval between the first battery cell and the second battery cell, Or thin.

Preferably, the current cut-off battery cell is ruptured due to an increase in pressure due to generation of gas in the battery cell when the battery cell is overcharged.

For this purpose, the current cutoff battery cell has an electrode assembly in which an anode plate, a separator, and a cathode plate are stacked and sealed together with an electrolyte in a pouch case, and the cathode plate includes a cathode collector; And a cathode active material layer formed on the cathode current collector, wherein the cathode active material layer includes a cathode active material, a gas generating material, a conductive material, and a binder.

The gas generating material may be at least one selected from the group consisting of lithium carbonate (Li ₂ CO ₃ ), calcium carbonate (CaCO ₃ ), lithium nickel oxide (LNO) and lithium oxalate Lt; / RTI >

The gas generating material may be included in the positive electrode in an amount of 0.1 to 20 wt% based on the combined weight of the positive electrode active material and the gas generating material.

The cathode active material layer may have a porous structure in which the gas generating material is connected to and fixed to the binder by the binder and has pores formed by void spaces between the gas generating materials.

The cathode active material and the gas generating material may be mixed.

Alternatively, the cathode active material layer includes a primer layer and an active material coating layer, and the primer layer includes the gas generating material, the conductive material, and the binder, and the active material coating layer includes the cathode active material, Lt; / RTI >

The gas generating material may be contained in an amount of 90 to 99.9% by weight of the solids constituting the primer layer.

The current cutoff battery cell uses the bimetal for the electrode leads of the first battery cell, the second battery cell, or the current cutoff battery cell to bend the electrode lead with a rise in temperature during overcharging so that the pouch case of the current cutoff battery cell It may be ruptured as it spreads.

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

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

According to the present invention, since the battery module is constituted by including the current cutoff battery cell between adjacent battery cells, if overcharge occurs when the battery module is used and the voltage of the current cutoff battery cell exceeds a specific voltage which is a threshold value, The battery cell is ruptured to block the current flow. Therefore, even when the secondary battery protection circuit is not operated, the flow of current can be blocked to prevent the battery from being charged any more, and the safety of the battery module can be enhanced. As described above, the battery module of the present invention implements the means for automatically blocking the flow of current when overcharging by using the current cut-off battery cell, thereby securing the safety of the battery module in addition to the overcharge prevention function of the secondary battery protection circuit .

According to the present invention, it is possible to provide the battery module by connecting the current cut-off battery cells between adjacent battery cells to form an electric connection path in series. When overcharging occurs such as when a specific voltage is reached, gas is generated from the gas generating material contained in the positive electrode plate of the current blocking battery cell. The current cutoff battery cell can be configured as a small or thin battery cell small enough to be disposed between neighboring battery cells and easily rupture due to gas generated therein. As a result, the adjacent battery cells are disconnected from the electric connection to block the current flow, so that the safety of the battery module can be secured.

According to the present invention, the lead connecting portion of the battery module can have a safety member called a current cut-off battery cell. By using a current-intercepting battery cell in the form of a " battery cell " without using a CID (Current Interrupt Device) type connector or a fuse dissolving as a safety member as a safety member, the current can be safely cut off in the event of overcharging. Such a current interruption battery cell is also advantageous in terms of resistance to a connector or a fuse.

According to the present invention, safety can be improved even if only the current-intercepting battery cell is added to the lead connecting portion without changing the battery cell constituting the battery module. It is not necessary to change the existing battery cell such as having a fuse in the electrode lead. Further, the current interrupting principle of the present invention does not break or melt the electrode leads of connected battery cells. Only the current interruption battery cell is ruptured to release the electrical connection. The fact that there is no change in the battery cell constituting the battery module is a great advantage in that the resistance in the battery module production side or the cell unit is not changed.

In particular, the present invention is characterized in that a current is cut off at a specific voltage through regulation of a gas generating material contained in a positive electrode plate of a current blocking battery cell, thereby coping with an " overcharge " For example, when lithium carbonate is used as the gas generating material, when the voltage of the current blocking battery cell reaches 4.8 V due to overcharging, the Li ₂ CO ₃ material is decomposed into the gas form of CO + CO ₂ , Which may cause the current interruption battery cell to rupture.

As described above, according to the present invention, it is possible to improve the safety of the battery module, the battery pack including the battery module, and the automobile including the battery pack, by providing the lead connection portion with the safety member during overcharging.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.

1 and 2 are views showing a state in which, for example, two pouch type secondary batteries are connected in series in a conventional battery module.

3 schematically illustrates a battery module according to an embodiment of the present invention.

4 schematically shows 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.

6 is a top view of a current blocking battery cell included in the battery module of FIG.

FIG. 7 is a schematic view of a battery module of FIG. 4 in which a current blocking battery cell can be connected between two adjacent battery cells.

8 is a cross-sectional view illustrating an embodiment of a positive electrode plate of an electrode assembly included in the current blocking battery cell of FIG.

FIG. 9 is a cross-sectional view illustrating another embodiment of the positive electrode plate of the electrode assembly included in the current blocking battery cell of FIG. 6;

FIG. 10 is a schematic view of a current blocking battery cell connected between adjacent two battery cells according to another embodiment of the present invention. FIG.

11 is a graph showing the results of the overcharge test according to the experimental example of the present invention.

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

13 is a view for explaining an automobile according to an 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, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible. In the drawings, the same reference numerals denote the same 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 act as working ions during charging and discharging to cause an electrochemical reaction between the positive electrode plate and the negative electrode plate.

On the other hand, even if the name of the secondary battery is changed depending on the type of the electrolyte or separator used in the lithium secondary battery, the type of the battery case used for packaging the secondary battery, the structure inside or outside of the lithium secondary battery, The secondary battery used in the present invention should be interpreted as being included in the category of the lithium secondary battery.

The present invention is also applicable to secondary batteries other than lithium secondary batteries. Therefore, even if the working ion is not lithium ion, any kind of secondary battery to which the technical idea of the present invention can be applied should be interpreted as falling within the scope of the present invention.

3 schematically illustrates a battery module according to an embodiment of the present invention.

Referring to FIG. 3, the battery module 100 includes two or more battery cells 60a, 60b, 60c, .... Each of the battery cells 60a, 60b, 60c, ... may be a secondary battery. Each battery cell 60a, 60b, 60c, ... may have positive electrode leads 70a, 70b, 70c, ... and negative electrode leads 80a, 80b, 80c,. The positive electrode leads 70a, 70b, 70c, ... and the negative electrode leads 80a, 80b, 80c, ... are electrically connected through the lead connecting portion B, Is connected. The lead connection portion B may be an indirect connection method as described with reference to FIG. 1 or a direct connection method as described with reference to FIG.

In the prior art described with reference to FIGS. 1 and 2, the lead connecting portion A does not have a safety member for overcharging. However, in the present invention, at least one of the plurality of lead connection parts B includes the current blocking battery cell 90. The current cut-off battery cell 90 is a safety member that cuts off the current flow during overcharging. The secondary battery needs to be protected from abnormal situations such as overcharge, overdischarge, overheating, overcurrent, etc. The present invention provides a battery module capable of protecting a secondary battery from overcharging.

3 illustrates that a current cutoff battery cell 90 is included between a first battery cell 60a and a second battery cell 60b, which are two adjacent battery cells, for example. The current cutoff battery cell 90 electrically connects the first battery cell 60a and the second battery cell 60b that are adjacent to each other and ruptures when overcharged, thereby disconnecting the electric connection to interrupt the current flow.

The current blocking battery cell 90 may also be a secondary battery. The current blocking battery cell 90 may also have a positive lead and a negative lead. The positive electrode lead of the current blocking battery cell 90 is connected to the negative electrode lead 80a of the first battery cell 60a and the negative electrode lead of the current blocking battery cell 90 is connected to the positive electrode lead of the second battery cell 60b 70b, a series connection state as shown in Fig. 3 can be obtained. The connection between the leads may be accomplished through, for example, ultrasonic welding, resistance welding, laser welding, conductive adhesive or the like, but the present invention is not limited thereto.

The current cutoff battery cell 90 may be included in one battery module 100 or more. A plurality of battery cells 60a, 60b, 60c, ... may be electrically connected to each other to form a battery module 100 having one current flow path, Even when any one of the lead connecting portions B includes the current blocking battery cell 90, the electrical connection can be cut off during overcharging.

Preferably, the current cutoff battery cell 90 is ruptured due to an increase in pressure due to generation of gas in the battery cell at a specific voltage at the time of overcharging. When the internal pressure due to the generation of the gas becomes equal to or greater than the sealing strength of the battery case of the current interruption battery cell 90, the battery case ruptures while being opened. As another example, the current cutoff battery cell 90 may be a bimetal that is used to bend the bimetal due to a temperature rise during overcharging and rupture as the battery case of the current cutoff battery cell 90 is opened. When the electrons are overcharged, the current is cut off when the voltage exceeds the specific voltage. The latter can be used when the temperature rises during overcharging.

On the other hand, a technique has been known in which lithium carbonate is included in the positive electrode active material layer so that the resistance of the positive electrode plate is greatly increased to thereby reach the overcharge end voltage. In the present invention, a gas generating material such as lithium carbonate is used, but the resistance of the positive electrode plate is increased to not reach the overcharge end voltage, but the internal pressure of the current blocking battery cell 90 It should be noted that there is a difference in that when the internal pressure is increased beyond the sealing strength of the case, the battery case is opened and ruptured to physically block the electrical connection path.

1 and 2, the lead connecting portion A has no over-charging safety member. In the present invention, however, the lead connecting portion B includes the current blocking battery cell 90 as an over-charging safety member . It should be noted that the safety element is implemented in the form of a " battery cell " rather than a simple CID type connector or a fused fuse. For this reason, there is an effect that the current can be safely cut off when overcharging. Because the current cutoff battery cell 90 is implemented in the form of a " battery cell ", it is advantageous in terms of resistance to connectors and fuses. If the fuse is inserted into the lead connecting portion A in the prior art shown in FIGS. 1 and 2, the resistance will be higher than that if not. In addition, fuses are difficult to cope with overcharging situations. When the overcurrent flows, the temperature of the secondary battery rises due to the resistance heat generation, and only the fuse is operated. In the present invention, the current blocking battery cell 90 is included, which is advantageous because it can be prevented from acting as a resistance component.

According to the present invention, safety can be improved even if only the current interrupting battery cell 90 is added to the lead connecting portion B without changing the battery cells 60a, 60b, 60c, ... constituting the battery module 100 . It is not necessary to change the existing battery cell such as having a fuse in the electrode lead. Further, the current interrupting principle of the present invention does not break or melt the electrode leads of connected battery cells. That is, instead of changing the existing battery cell to provide a mechanically weak structure or a structure for melting at a certain temperature, only the current cutoff battery cell 90 is ruptured to release the electrical connection. The fact that there is no change in the battery cell constituting the battery module is a great advantage in that the resistance in the battery module production side or the cell unit is not changed.

The battery cells 60a, 60b, 60c, ... are not limited to the specific types, the number and the connection methods of the battery cells 60a, 60b, 60c, ... included in the battery module 100, Type secondary battery. The present invention is not limited to the specific type, number, connection type, etc. of the current cut-off battery cell 90, but the current cut-off battery cell 90 may also be a pouch type secondary cell. Hereinafter, the present invention will be described in more detail with reference to embodiments in which both battery cells constituting a battery module and a current cutoff battery cell are pouch type secondary batteries.

4 schematically shows 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. 6 is a top view of a current blocking battery cell included in the battery module of FIG.

The battery module 1000 shown in FIG. 4 shows 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 secondary battery 200 as shown in Fig. 5, and has the same structure as each other.

Referring to FIG. 5, the pouch type secondary battery 200 includes an electrode assembly 210 and an electrolyte solution enclosed 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 in order to seal the electrode assembly 210 and electrolyte contained therein, and to protect them from the outside.

One end of the cathode lead 240 and the cathode lead 250 are connected to both ends of the electrode assembly 210 and the other ends are exposed to the outside of 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 the other 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 to the outside of the pouch case 230 are used to electrically connect the plurality of pouch type secondary batteries as shown in FIG.

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 can prevent the short circuit between the electrode leads 240 and 250 and the metal layer of the pouch case 230 and improve the sealing property of the pouch case 230. [ The contact resistance may be greater when the electrode leads 240 and 250 made of metal and the pouch case 230 made of the polymer are thermally welded together, so that the surface adhesion force may be lowered. However, when the lead film 260 is provided as in the above embodiment, such a deterioration in adhesion can be prevented. In addition, it is preferable that the lead film 260 is made of an insulating material so as to prevent current from being applied to the pouch case 230 from the electrode leads 240 and 250. The lead film 260 is made of a film having insulation and heat sealability. The lead film 260 may be made of at least one material layer (single film or multilayer film) selected from, for example, polyimide (PI), polypropylene, polyethylene and polyethylene terephthalate .

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 interposed therebetween. The unit cells can be simply stacked, stacked and folded, or can be made of an electrode assembly in the form of a jelly roll. The method of manufacturing the electrode assembly of various types is well known, so a detailed description thereof 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 in the form of a biocell composed of a negative electrode plate / separator / positive electrode plate or a negative electrode plate / separator / positive electrode plate / separator / negative electrode plate or a positive electrode plate / separator / negative electrode plate / separator / positive electrode plate. The positive electrode lead 240 and the negative electrode lead 250 are drawn out from the pouch case 230 in opposite directions to each other. However, both the positive electrode lead 240 and the negative electrode lead 250 But does not exclude the unidirectional battery mode that is drawn out from the pouch case 230 in one direction.

Referring to FIGS. 4 and 5, the battery cells 200a and 200b have electrode leads protruding from both ends of the battery cells 200a and 200b, and the positive electrode leads 240a of the battery cell 200a, for example, Are laminated so as to be aligned with the negative electrode lead 250b of the battery cell 200b. That is, the plurality of battery cells are stacked alternately so that the electrode leads arranged side by side are opposite in polarity. The battery cells 200a, 200b, 200c,... May be connected in series. In FIG. 4, the other ends of the electrode leads 240a, 250b are bent to the left or right, And then welding them by overlapping each other. That is, the lead connecting portion B shown in FIG. 3 is provided by bending and connecting the battery cell electrode leads 240a and 250b in FIG. 4, and the battery cells 200a, 200b, 200c, ... Are connected to each other through the lead connecting portion B.

In Fig. 4, 11 battery cells as a whole are included. The electrode leads of each battery cell are vertically bent so that the electrode leads of the adjacent battery cells and the vertically bent portions overlap each other to form the lead connecting portion B. More specifically, the inner electrode leads except for the electrode leads located at the outermost positions from one side of the stacked battery cells 200a, 200b, 200c,... Are folded and overlapped with each other, and then the bent electrode lead portions are electrically connected . On the other side of the stacked battery cells 200a, 200b, 200c,..., The electrode leads are bent and overlapped with each other, and then the electrode lead portions are welded to electrically connect the bent electrode lead portions.

In FIG. 4, the battery cells 200a, 200b, 200c,... Are stacked in a vertical direction. When the electrode lead is bent, one of the electrode leads in the battery cell is vertically bent in the right direction (or the outer side of the battery module), and the other electrode lead is bent in the left direction (or inward of the battery module). As a result, the lead connecting portions B to be coupled are bent in a " C " shape so that electrode leads having different polarities are folded and overlapped. The lead connecting portions B are arranged side by side along the horizontal direction. This process can be performed in the opposite process. For example, the electrode leads may be folded and bent before the battery cells are stacked, and the corresponding portion may be welded.

Meanwhile, FIG. 4 shows a direct connection method in which electrode leads are overlapped. However, as described with reference to FIG. 1, an indirect connection method using a connection bar is also possible. For example, the present invention can be applied to a case where a battery module is formed by welding a bus bar together with an electrode lead, or a case where an electrode lead and an external circuit are welded to form a battery module. The battery module 1000 of the present embodiment includes the current blocking battery cell 300 as shown in FIG. 6 in the lead connecting portion B thereof.

Referring to FIG. 6, the current blocking battery cell 300 is also enclosed in the pouch case 330 in which the electrode assembly 310 and the electrolyte are housed together. The pouch case 330 of the current cutoff battery cell 300 is configured to include a metal layer, an outer resin layer, and an inner resin layer in order to seal the electrolyte assembly and electrolyte contained therein, and to protect them from the outside .

The positive electrode lead 340 and the other end of the negative electrode lead 350 are connected to both ends of the electrode assembly 310 and are exposed to the outside of the pouch case 330. One end of the positive electrode lead 340 is electrically connected to the positive electrode plate of the electrode assembly 310 and the other end of the negative electrode lead 350 is electrically connected to the negative electrode plate of the electrode assembly 310. A lead film 360 is interposed between the pouch case 330 and the electrode leads 340 and 350. The lead film 360 is provided to further improve the adhesion between the pouch case 330 and the electrode leads 340 and 350. The other ends of the exposed electrode leads 340 and 350 are used to electrically connect the battery cells 200a and 200b to each other as shown in FIG.

Here, the electrode assembly 310 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 interposed therebetween. The unit cells can be simply stacked, stacked and folded, or can be made of an electrode assembly in the form of a jelly roll. For example, the electrode assembly 310 may be formed by stacking a negative electrode plate, a separator, and a positive electrode plate. The electrode assembly 310 may be in the form of a biocell composed of a negative electrode plate / separator / positive electrode plate or a negative electrode plate / separator / positive electrode plate / separator / negative electrode plate or a positive electrode plate / separator / negative electrode plate / separator / positive electrode plate. The positive electrode lead 340 and the negative electrode lead 350 are drawn out from the pouch case 330 in opposite directions to each other in the present embodiment. However, both of the positive electrode lead 340 and the negative electrode lead 350 But does not exclude the unidirectional battery mode that is drawn out from the pouch case 330 in one direction.

FIG. 7 is a schematic view of a battery module of FIG. 4 in which a current blocking battery cell can be connected between two adjacent battery cells.

Referring to FIGS. 4 and 7 together, when two adjacent battery cells in the battery module 1000 are referred to as a first battery cell 200a and a second battery cell 200b, The current blocking battery cell 200 and the current blocking battery cell 300 are connected in series and the current blocking battery cell 300 and the second battery cell 200b are connected in series. Specifically, the anode lead 350 of the current blocking battery cell 300 is connected to the cathode lead 240a of the first battery cell 200a, and the cathode lead 340 of the current blocking battery cell 300 is connected to the second And is connected to the negative electrode lead 250b of the battery cell 200b. The positive electrode lead 240a of the first battery cell 200a and the negative electrode lead 250b of the second battery cell 200b are electrically connected to each other through the electrode leads 340 and 350 of the current- So that the first and second battery cells 200a and 200b are electrically connected to each other. The connection may be made by a method customary in the art and may be, for example, coupled and connected by ultrasonic welding, but is not limited thereto.

There is no problem in the resistance of the battery module 1000 even if the positive electrode lead 240a of the first battery cell 200a and the negative electrode lead 250b of the second battery cell 200b are not directly connected. In order to maintain the gap between the battery cells 200a, 200b, 200c, ... shown in the battery module 1000 in FIG. 4, only the electrode leads to which the current- And may have a shorter length.

In the present invention, the positions of two adjacent battery cells electrically connected by the current-blocking battery cell 300 are not particularly limited. For example, the battery cells in the middle of the battery module 1000 may be electrically connected by the current cutoff battery cell 300, or the battery cells at the outermost battery module 1000 may be electrically connected to the current cutoff battery cell 300, As shown in Fig.

The size of the current cutoff battery cell 300 should be determined in consideration of the space in which the current cutoff battery cell 300 is disposed. 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 connected to the first and second battery cells 200a and 200b, The current blocking battery cells 300 are placed in parallel with the stacking direction and are bent toward the electrode leads 240a, 350, and 340b between the bent portions of the electrode leads 240a and 250b, And 250b are connected to each other.

7, the current-blocking battery cell 300 may be formed by bending the respective electrode leads 240a and 250b without affecting the interval between the first battery cell 200a and the second battery cell 200b, The first battery cell 200a and the second battery cell 200b may be smaller or thinner than the first battery cell 200a and the second battery cell 200b.

For example, it is preferable that the size of the current-cutoff battery cell 300 is designed to be smaller than the interval (distance) between two electrode leads from two adjacent battery cells. It is preferable that the current intercepting battery cell 300 does not have the same or a large difference from the electrode lead thickness of adjacent battery cells so that welding with the electrode leads of adjacent battery cells can be easily performed. Since the current blocking battery cell 300 can be mounted on the lead connecting portion B only by inserting the current blocking battery cell 300 into a small or thin shape, There is an advantage that you do not have to pay.

In the present embodiment, the current blocking battery cell 300 electrically connects the first battery cell 200a and the second battery cell 200b, which are adjacent to each other, and ruptures when overcharged, thereby releasing the electrical connection. The electrical connection between the first battery cell 200a and the second battery cell 200b is such that when the battery module 1000 is overcharged, for example, when the battery module 1000 reaches a certain voltage, for example 5.0 V, Gas is generated in the battery cell 300 and is cut off when the current-intercepting battery cell 300 ruptures, so that safety against overcharging can be ensured.

As described above, according to the present embodiment, the current interrupting battery cell 300 is included between the adjacent battery cells 200a and 200b, so that the electric connecting path can be formed by series connection. When an overcharge occurs, such as when a specific voltage is reached, the current cutoff battery cell 300 can be configured to generate gas from the gas generating material contained in the positive plate. The current cutoff battery cell 300 can be configured as a small or thin battery cell small enough to be disposed between adjacent battery cells 200a and 200b and easily rupture due to gas generated therein. As a result, the adjacent battery cells 200a and 200b are disconnected from each other and the current flow is interrupted, so that the safety of the battery module 1000 can be secured.

8 is a cross-sectional view illustrating an embodiment of a positive electrode plate of an electrode assembly included in the current blocking battery cell of FIG.

Referring to FIG. 8, the positive electrode plate 320 includes a positive electrode collector 322 and a positive electrode active material layer 324.

The positive electrode active material layer 324 is formed on the positive electrode collector 322 and includes a positive electrode active material, a gas generating material 325, a conductive material, and a binder. The cathode active material and the gas generating material 325 may be mixed. That is, the gas generating material 325 can be uniformly distributed in the cathode active material layer 324. Therefore, when the positive electrode plate 320 is formed, the gas generating material 325 is put into the solution of the binder together with the positive electrode active material and the conductive material and stirred to form the slurry of the positive electrode active material 322, The anode active material layer 324 may be formed on at least one side of both surfaces. If necessary, the slurry of the cathode active material blended with the gas generating material may be coated and dried and then subjected to a rolling step.

As used herein, the term 'gas generating material' refers to a material that generates gas at a specific voltage, and includes, but not limited to, lithium carbonate (Li ₂ CO ₃ ), calcium carbonate (CaCO ₃ ), lithium nickel oxide (LNO: Lithium Nickel Oxide, Lithium Oxalate, and the like. Preferably, the gas generating material 325 included in the positive electrode active material layer 324 may be one or a mixture of two or more selected from the group consisting of lithium carbonate, calcium carbonate, lithium nickel oxide, and lithium oxalate.

In particular, it is possible to cut off the current at a specific voltage by controlling the gas generating material 325 included in the positive electrode plate 320 of the current blocking battery cell 300. The gas generating material 325 is selected depending on the battery model so that it can be decomposed and vaporized at a specific voltage set as an overcharge voltage. For example, if the current is over 4.5V, which is generally regarded as an overcharged state, the current must be cut off to stop charging. Among the gas generating substances 325, lithium carbonate for example is suitable because it decomposes at 4.8 V or more. For example, when lithium carbonate is used as the gas generating material 325, when the internal pressure reaches 4.8 V due to overcharging, the internal pressure of the Li ₂ CO ₃ material is suddenly decomposed into the gas form of CO + CO ₂ , The current blocking battery cell 300 can be ruptured.

The gas generating material 325 may be included in the positive electrode plate 320 in an amount of 0.1 to 20% by weight based on the combined weight of the positive electrode active material and the gas generating material 325. When the gas generating substance 325 is included in the above amount, the gas may be generated during overcharging so that the current blocking battery cell 300 is ruptured.

The gas generating material 325 particles, especially lithium carbonate particles, may have shapes such as spheres, ellipses, polygons, but are not limited thereto. Also, in the present specification, when it is referred to as 'spherical shape' or 'elliptical shape', it does not mean a complete 'spherical shape' or 'elliptical shape' but means a spherical shape or an elliptical shape It is a broad sense. Such lithium carbonate particles may have a particle diameter of 0.1 to 50 탆.

The cathode active material used in the current cutoff battery cell 300 is not particularly limited and may be the same as or different from the cathode active material of the battery cells 200a, 200b, 200c, ... used in the battery module 1000. [ For example, the cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1 - x M x O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure such as LiNi _x Mn _{2 - x} O ₄ (x = 0.01 to 0.6); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, 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 fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists in bonding of the active material, the gas generating material, the conductive material and the like to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, various copolymers and the like.

The cathode active material layer 324 can be a porous structure having pores formed by the voids between the gas generating materials 325 and the gas generating materials 325 being connected and fixed to each other by such a binder. The porous structure with the pores thus formed increases the area of reaction with the electrolyte, especially the electrolyte, in the assembled battery. Therefore, gas generation is more actively performed. Pores that are not filled with electrolyte may form a path of travel through which the generated gas is spread. It is important to widen the reaction area of the positive electrode active material layer 324 in order for the gas generating material 325 to function efficiently. Even if it is formed in a narrow area, it may be formed so as to have a large surface area. For this purpose, a large number of small pores may be formed in the cathode active material layer 324, for example, by regulating the size of the particles of the gas generating material 325, a desired result can be achieved.

The positive electrode plate 320 of the current blocking battery cell 300 may further include an additive such as a filler in the positive electrode active material layer 324 as needed. The filler is optionally used as a component for suppressing expansion of the positive electrode active material layer 324 and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefins such as polyethylene and polypropylene A polymer; Fibrous materials such as glass fibers and carbon fibers are used.

The cathode current collector 322 is generally made to have a thickness of 3 to 500 μm. The positive electrode collector 322 is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the positive electrode collector 322 may be made of stainless steel, aluminum, nickel, titanium, The surface of the steel may be surface treated with carbon, nickel, titanium, silver, or the like. The anode current collector 322 may be formed of fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The negative electrode plate included in the electrode assembly 310 of the current blocking battery cell 300 may be manufactured by applying, drying, and pressing the negative electrode active material slurry on the negative electrode collector, and may further include a conductive material, A filler and the like may optionally be further included. The anode current collector is generally made to have a thickness of 3 to 500 μm. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. As in the case of the cathode current collector 322, fine unevenness may be formed on the surface to enhance the bonding force of the anode active material. The cathode active material may be used in various forms such as a film, sheet, foil, net, porous body, foam, .

The negative electrode active material may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Au x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{AuO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like can be used.

In the current blocking battery cell 300, a separation membrane is interposed between the cathode plate 320 and the anode plate, and an insulating thin film having high ion permeability and mechanical strength may be used, but the present invention is not limited thereto. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The electrolyte solution used in the current blocking battery cell 300 may be an electrolyte solution and a lithium salt. The electrolyte solution may be a non-aqueous organic solvent, an organic solid electrolyte, or an inorganic solid electrolyte, but is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butylolactone, Tetrahydrofuran, tetrahydrofuran, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, Examples of the organic solvent include methyl acetate, phosphoric acid triester, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, Propylenic organic solvents such as methylmethyl, ethylpropionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

FIG. 9 is a cross-sectional view illustrating another embodiment of the positive electrode plate of the electrode assembly included in the current blocking battery cell of FIG. 6;

Referring to FIG. 9, the positive electrode plate 320 'includes a positive electrode collector 322, a primer layer 326, and an active material coating layer 327.

The primer layer 326 is formed on the cathode current collector 322 and includes a gas generating material 325, a conductive material, and a binder. The active material coating layer 327 is formed on the primer layer 326 and includes a cathode active material, a conductive material, and a binder. That is, in this embodiment, the gas generating material 325 is not included in the active material coating layer 327.

Therefore, when the positive electrode plate 320 'is formed, the gas generating material 325 is charged into the solution of the binder together with the conductive material and stirred to form the gas generating material slurry, and then the positive electrode current collector 322 is formed on at least one surface A primer layer 326 may be formed first and then a cathode active material slurry including a cathode active material, a conductive material, and a binder may be formed and coated on the primer layer 326 to form an active material coating layer 327.

At this time, it is preferable that the gas generating material 325 is contained in an amount of 90 to 99.9% by weight of the solid content constituting the primer layer 326. When the content of the gas generating substance 325 is less than the lower limit value, the electrical resistance is insufficiently increased. When the content of the gas generating substance 325 is more than the upper limit value, It can become scarce.

The rest of the contents can be used as described above with reference to FIG.

In this embodiment, a gas is generated in the primer layer 326 between the cathode current collector 322 and the active material coating layer 327. As a result, the current blocking battery cell 300 quickly reaches the overcharge end voltage so that the safety of the battery module 1000 including the current blocking battery cell 300 can be secured.

In the foregoing embodiments, the current cut-off battery cell is based on the gas generation principle. As another embodiment, it is possible to use a bimetal which is bent at a temperature rise in the current cutoff battery cell. For example, when the bimetal is used for the electrode leads of the first battery cell 200a, the second battery cell 200b, or the current-blocking battery cell 300 adjacent to each other in the battery module 1000 as shown in FIG. 4, The electrode lead may be bent to raise the temperature so that the pouch case 330 of the current interruption battery cell 300 ruptures while being opened. 10 shows an example in which the positive electrode lead 240a 'of the first battery cell 200a is formed of bimetal.

10, the positive electrode lead 240a 'of the first battery cell 200a is made of bimetal and the end of the positive electrode lead 240a' is connected to the current intercepting battery cell 300 through the bonding member 500. [ Respectively.

The bimetal is formed such that a metal having a large thermal expansion coefficient constitutes the lower portion 242 of the lead and is connected to the negative electrode lead 350 of the current blocking battery cell 300 and the metal having a small thermal expansion coefficient constitutes the upper portion 241 of the lead . Non-limiting examples of the metal having a large thermal expansion coefficient include copper / zinc alloy, nickel / molybdenum / iron alloy, and nickel / manganese / iron alloy. Non-limiting examples of metals having a small thermal expansion coefficient include, but are not limited to, nickel / iron alloys.

The adhesive member 500 is not particularly limited as long as it is commonly used in the art, and may be, for example, an insulating double-sided tape or an adhesive.

The positive electrode lead 240a 'of the first battery cell 200a made of bimetal is bent in a direction away from the current blocking battery cell 300 due to a difference in thermal expansion coefficient during generation of heat due to overcharging, The pouch case 330 of the current intercepting battery cell 300 attached to the positive electrode lead 240a 'of the first battery cell 200a is ruptured by the member 500 so that the current can be more easily cut off.

In this embodiment, the positive electrode lead 240a 'of the first battery cell 200a is made of bimetal. However, the electrode lead of the current-intercepting battery cell 300 may be formed of bimetal Do. At this time, since there is no change of the existing battery cell, the resistance on the side of the mass production or the cell unit is not changed is better than the previous embodiment.

According to the structure of the present invention described above, since the current interrupting battery cell is included in the lead connecting portion, the current interrupting battery cell ruptures during overcharging, thereby blocking current flow. Therefore, for example, even if the overcharge prevention function of the secondary battery protection circuit is not normally operated, it is possible to prevent the current from flowing and prevent the battery from being charged further. In addition, since the current interrupting battery cell is included in the lead connecting portion, there is an advantage that a separate space is not required for mounting the current interrupting battery cell.

Since the battery module according to the present invention has excellent safety, it is suitable for use as a power source of a middle- or large-sized apparatus requiring high temperature stability, long cycle characteristics, and high rate characteristics. Preferred examples of the above-mentioned middle- or large-sized apparatus include a power tool which is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And ESS, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in more detail by explaining the result of the overcharge test according to the experimental example of the present invention, but the scope of the present invention is not limited thereto.

The battery cells 200a and 200b are manufactured by reducing the volume of the mass production battery to a small size on the laboratory scale and the current blocking battery cells 300 smaller than the battery cells 200a and 200b are manufactured. And an overcharge test was carried out. The manufacturing method of the battery cells 200a and 200b and the current blocking battery cell 300 is the same as that of a conventional pouch type secondary battery manufacturing method.

The manufacturing method of the battery cells 200a and 200b was as follows. LiCoO ₂ cathode active material having a D50 of about 15 to 20 μm, Super P as a conductive material, and polyvinylidene fluoride as a binder polymer were mixed at a weight ratio of 92: 4: 4 and then NMP (N-methyl pyrrolidone) To prepare a cathode active material slurry. The cathode active material slurry thus prepared was applied to a cathode current collector made of aluminum foil and dried in a vacuum oven at 120 ° C to prepare a cathode plate.

On the other hand, MCMB (mesocarbon microbead) was used as an anode active material, super P as a conductive material and PVdF as a binder were mixed at a ratio (weight ratio) of 92: 2: 6 and dispersed in NMP to prepare an anode active material slurry Was coated on an anode current collector made of copper foil and dried to prepare a negative electrode plate.

An electrode assembly was fabricated using a polyethylene separator between the cathode and anode plates. Electrode leads were connected to the electrode assembly and placed in a pouch case. Ethylene carbonate (EC) and dimethyl carbonate (DMC) solutions having a volume ratio of 1: 1 in which 1 M of LiPF ₆ was dissolved were injected into the electrolyte and then sealed.

The method of manufacturing the current cut-off battery cell 300 includes the step of further including the gas generating material in the positive electrode active material layer and the step of reducing the thickness of the current cut-off battery cell 300 to as small as the electrode lead size of the battery cells 200a and 200b And similar to the method of manufacturing the battery cells 200a and 200b. As the gas generating material, lithium carbonate having a particle diameter of 5.0 탆 was used.

7, the electrode leads of the battery cell 200a and the electrode leads of the current cutoff battery cell 300 are connected by ultrasonic welding, and the other electrode leads of the current cutoff battery cell 300 are connected to the battery cell 200b, and connected in series.

Overcharging tests on the serially connected unit modules proceeded in two steps. First, CC-CV was charged at room temperature (25 ℃) and atmospheric pressure to make 100% state of SOC (1st step: SOC 100% setting) And the SOC was continuously increased to verify whether the cut-off battery cell 300 can cut off current (second step: overcharge). Charge / discharge test equipment was used for overcharge evaluation. The terminal channels of the charge and discharge test apparatus were connected to the respective electrode leads of the battery cells 200a and 200b and the current cutoff battery cell 300 to measure the voltage (full cell voltage) of each battery cell while overcharging. Charge / discharge test equipment is available from several manufacturers, for example Hioki HiTester.

The results are shown in Fig. 11 is a graph showing the results of the overcharge test according to the experimental example of the present invention.

Referring to FIG. 11, the voltages of the battery cells 200a and 200b and the current cutoff battery cell 300 gradually increase from about 4.4 V as the overcharging progresses from SOC 100%. The voltage of the current cut-off battery cell 300 rises faster than the voltage of the battery cells 200a and 200b according to the progress of overcharging. This is because the current blocking battery cell 300 is smaller than the battery cells 200a and 200b and has a smaller capacity. For example, assuming that the battery cells 200a and 200b are 40 mAh cells, the current cutoff battery cell 300 is small enough to be a 10 mAh cell. Therefore, the voltage of the current cutoff battery cell 300 It grows faster. When the voltage of the current blocking battery cell 300 is increased to about 4.9 V or more, the generation of gas in the current blocking battery cell 300 is accelerated, so that the battery voltage rapidly rises. At the point where the SOC is 130%, the current cutoff battery cell 300 shows a voltage drop to 0V. It is impossible to measure the voltage of the current cutoff battery cell 300 as a result of the current cutoff battery cell 300 rupturing without enduring the internal pressure. The voltage of the battery cells 200a and 200b converges to OCV (open circuit voltage) after SOC 130%. The charging current is continuously supplied, but the electric connection path is cut off due to the rupture of the current cut-off battery cell 300. Accordingly, it was confirmed through the experiment that the current cut-off battery cell 300 effectively operated as a safety member when an overcharging state occurred in which the voltage of the SOC 130% and the voltages of the battery cells 200a and 200b became 4.8V or more.

12 is a view for explaining a battery pack according to an embodiment of the present invention. 13 is a view for explaining an automobile according to an embodiment of the present invention.

12 and 13, the battery pack 1200 may include at least one battery module according to the preceding embodiment, for example, the battery module 1000 of the second embodiment and a pack case 1210 for packaging the battery module 1000 . In addition to the battery module 1000 and the pack case 1210, the battery pack 1200 according to the present invention may include various devices for controlling the charging and discharging of the battery module 1000, such as a BMS (Battery Management System) Sensors, fuses, and the like.

The battery pack 1200 may be provided in the automobile 1300 as a fuel source of the automobile 1300. By way of example, the battery pack 1200 may be provided in an automobile 1300 in an electric vehicle, a hybrid vehicle, or any other manner in which the battery pack 1200 can be used as a fuel source.

Preferably, the automobile 1300 may be an electric vehicle. The battery pack 1200 may be used as an electric energy source for driving the automobile 1300 by providing a driving force to the motor 1310 of the electric vehicle. In this case, the battery pack 1200 has a high nominal voltage of 100 V or more. It is set to 270V for hybrid cars.

The battery pack 1200 may be charged or discharged by the inverter 1320 in accordance with the driving of the motor 1310 and / or the internal combustion engine. The battery pack 1200 can be charged by a regenerative charging device coupled with a break. The battery pack 1200 can be electrically connected to the motor 1310 of the automobile 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. Estimates and manages battery pack 1200 status information such as SOC (State Of Charge), SOH (State Of Health), maximum input / output power allowable amount, and output voltage of the battery pack 1200. It is also possible to control the charging or discharging of the battery pack 1200 using this state information, and further estimate the replacement time of the battery pack 1200. [

The ECU 1330 is an electronic control device for controlling the state of the automobile 1300. For example, torque information is determined based on information such as an accelerator, a brake, and a speed, and the output of the motor 1310 is controlled to match the torque information. The ECU 1330 also sends a control signal to the inverter 1320 so that the battery pack 1200 can be charged or discharged based on status information of the SOC, SOH, etc. of the battery pack 1200 transmitted by the BMS. The inverter 1320 causes the battery pack 1200 to be charged or discharged based on the control signal of the ECU 1330. The motor 1310 drives the automobile 1300 based on control information (e.g., torque information) transmitted from the ECU 1330 using the electric energy of the battery pack 1200. [

The automobile 1300 includes the battery pack 1200 according to the present invention. The battery pack 1200 includes the battery module 1000 having improved safety as described above. Therefore, the stability of the battery pack 1200 is improved, and the battery pack 1200 is excellent in stability and can be used for a long time, so that the automobile 1300 including the battery pack 1200 is safe and easy to operate.

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

As described above, the apparatus, apparatus, and equipment including the battery pack 1200 such as the battery pack 1200 and the automobile 1300 according to the present embodiment include the battery module 1000 described above, A battery pack 1200 having all of the merits of the battery pack 1200 and an automobile 1300 having such a battery pack 1200 can be realized.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. It is to be understood that various changes and modifications may be made without departing from the scope of the appended claims.

Claims (17)

1. 1. A battery module comprising at least two battery cells,

   And a current cutoff battery cell for electrically connecting the adjacent first battery cell and the second battery cell to each other, and disconnecting the electric connection by rupture when the battery is overcharged.
2. The method according to claim 1,

   Wherein each of the first battery cell, the second battery cell, and the current intercepting battery cell has a structure in which an electrode assembly having one end of an electrode lead of opposite polarity is connected to both ends of the electrode assembly, And the other end of the pouch type battery is exposed to the outside of the pouch case.
3. The method according to claim 1,

   Wherein the first battery cell and the current cutoff battery cell are connected in series, and the current cutoff battery cell and the second battery cell are connected in series.
4. 3. The method of claim 2,

   Wherein an electrode lead of the first battery cell and an electrode lead of the second battery cell are connected to each other via an electrode lead of the current blocking battery cell.
5. 5. The method of claim 4,

   The first battery cell and the second battery cell are alternately stacked such that the respective electrode leads are opposite in polarity, 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 are Wherein the current blocking battery cells are folded toward each other along the stacking direction and between the bent portions of the respective electrode leads, the current blocking battery cells are arranged in parallel to the stacking direction and connected between the respective electrode leads.
6. 6. The method of claim 5,

   Wherein the current blocking battery cell is smaller than the first battery cell and the second battery cell so as to be positioned between the bent portions of the respective electrode leads without affecting the interval between the first battery cell and the second battery cell, Or thin.
7. 3. The method of claim 2,

   Wherein the current blocking battery cell is ruptured due to an increase in pressure due to gas generation in the battery cell when the battery cell is overcharged.
8. 8. The method of claim 7,

   The current blocking battery cell

   An electrode assembly in which a cathode plate, a separation membrane, and a positive electrode plate are stacked is sealed in a pouch case together with an electrolyte solution,

   The positive electrode plate includes a positive electrode collector; And

   And a positive electrode active material layer formed on the positive electrode current collector,

   Wherein the positive electrode active material layer comprises a positive electrode active material, a gas generating material, a conductive material, and a binder.
9. 9. The method of claim 8,

   The gas generating material may be at least one selected from the group consisting of lithium carbonate (Li ₂ CO ₃ ), calcium carbonate (CaCO ₃ ), lithium nickel oxide (LNO) and lithium oxalate And the battery module is a mixture.
10. 9. The method of claim 8,

    Wherein the gas generating material is contained in the positive electrode plate in an amount of 0.1 to 20 wt% based on the combined weight of the positive electrode active material and the gas generating material.
11. 9. The method of claim 8,

    Wherein the gas generating materials are connected and fixed to each other by a binder, and are porous structures having pores formed by void spaces between the gas generating materials.
12. 9. The method of claim 8,

    Wherein the cathode active material and the gas generating material are mixed.
13. 9. The method of claim 8,

    Wherein the cathode active material layer includes a primer layer and an active material coating layer,

    Wherein the primer layer includes the gas generating material, the conductive material, and the binder,

    Wherein the active material coating layer includes the positive electrode active material, the conductive material, and the binder.
14. 14. The method of claim 13,

    Wherein the gas generating material is contained in an amount of 90 to 99.9 wt% of the solid content constituting the primer layer.
15. 3. The method of claim 2,

    Wherein the electrode leads of the first battery cell or the second battery cell are made of bimetal,

    The bimetal is formed by stacking a metal having a large thermal expansion coefficient and a metal having a small thermal expansion coefficient.

    A metal having a large thermal expansion coefficient is coupled to the electrode lead of the current blocking battery cell,

    Wherein an end of a metal having a large thermal expansion coefficient is bonded to the pouch case of the current interruption battery cell by an adhesive member.
16. At least one battery module according to any one of claims 1 to 15; And

    And a pack case for packaging the at least one battery module.
17. An automobile comprising at least one battery pack according to claim 16.

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