KR101543477B1 - Battery module and lithium secondary battery pack comprising the same - Google Patents

Abstract

The present invention relates to a battery module and a lithium secondary battery pack including the same, and more particularly, to a battery module including two or more pouch type unit cells and a module case for housing the unit cells, A thermally conductive heat dissipating unit including at least one heat dissipating plate which is in contact with a large area surface of the unit cell and the module case is inserted into the module case so as to perform a heat dissipating function, And a lithium secondary battery pack including the battery module.
The present invention can effectively remove heat generated in a cell during charging and discharging through a simple structure, improve external impact characteristics and energy density, and can improve the strength of the metal layer itself, which is essential in the case of a laminate sheet of a pouch- And it is possible to minimize the welding sealing surface of the outer can in manufacturing the battery module.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery module and a lithium secondary battery pack including the battery module.

The present invention relates to a battery module having a heat dissipating unit and a lithium secondary battery pack including the battery module.

Due to the development of technology and demand for mobile devices, demand for secondary batteries is also rapidly increasing. Of these, lithium secondary batteries, which have high energy density and high operating voltage and excellent lifespan characteristics, Is widely used. In addition, lithium-ion secondary batteries have attracted a great deal of attention as energy sources for electric vehicles and hybrid electric vehicles, which are being proposed as alternatives to solve the environmental pollution and global warming problems of conventional gasoline vehicles and diesel vehicles that use fossil fuels And is in the process of commercialization.

2. Description of the Related Art [0002] Medium- and large-sized devices such as electric vehicles and hybrid electric vehicles use a battery module in which a large number of unit cells are electrically connected to each other due to the necessity of high output and large capacity. Since the size and weight of the battery module are directly related to the accommodating space and output of the middle- or large-sized device, manufacturers are trying to manufacture a battery module capable of reducing the size and weight while securing a high output.

On the other hand, the secondary battery is classified into a cylindrical battery, a prismatic battery and a pouch-shaped battery according to the external and internal structural characteristics. Among them, a pouch-type battery which can be stacked with a high degree of integration, .

In a battery module including a plurality of unit cells capable of charging and discharging, one of the most serious problems is safety. The safety problem of the battery module is caused by deterioration of module components due to heat generation, external impact, and internal short circuit.

That is, although stacking a plurality of unit cells has a high degree of allotment, it is difficult to remove heat generated during charging and discharging, Safety can be seriously damaged. Particularly, in a battery requiring high-speed charging / discharging characteristics such as an electric vehicle or a hybrid electric vehicle, since a large amount of heat is accompanied in a process of instantaneously providing a high output power, the need for effective heat dissipation is greater.

Unlike a prismatic battery, the outer surface of a laminate sheet of a pouch-type battery widely used for a battery module includes a polymer resin layer. Since most of the materials of the polymer resin layer are low in thermal conductivity, No, it is vulnerable to external shock and requires additional components to ensure safety.

In addition, in the pouch type battery, a metal layer such as aluminum (Al) is included in a laminate sheet in order to cut off moisture and gas. However, since the metal layer requires a higher cost material than the polymer resin layer, .

In this connection, in Japanese Patent Application Laid-Open No. 2001-297741, a metal heat collecting plate having excellent thermal conductivity is interposed between respective batteries, and a heat pipe attached to the heat collecting plate is connected to a heat dissipating unit provided on the outer surface of the battery pack case Thereby releasing heat inside the battery pack.

However, since the cross-sectional area of the portion connecting the heat pipe and the heat dissipation unit is small, the battery pack of the above structure can not efficiently transmit the heat inside the battery pack case to the heat dissipation unit, Is complicated and has a disadvantage of occupying a large space.

Therefore, it is necessary to develop a battery module capable of exhibiting excellent heat radiation characteristics even through a simple and compact structure, capable of improving external impact characteristics, and capable of eliminating a metal layer in a laminate sheet casing of a conventional pouch type battery .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art,

The inventors of the present application have conducted intensive research and various experiments and have inserted a thermally conductive heat dissipating unit which is in contact with a large area surface of the unit cell and the module case inside the module case so that the module case itself can perform a heat dissipating function And the module case is completely sealed. In this case, the heat generated from the unit cells can be effectively removed through a simple structure, and the battery module can be manufactured in a very compact structure And it has been confirmed that the expensive laminate sheet covering material including the metal layer can be replaced by only a low-cost polymer resin film.

According to an aspect of the present invention, there is provided a battery module including two or more pouch type unit cells and a module case for housing the unit cells, And a thermally conductive heat dissipating unit including at least one heat dissipating plate, which is in contact with the large-sized surface of the unit cell and the module case, is inserted into the module case.

The heat dissipation unit may further include a support plate that is integrated with the heat dissipation plate to support the heat dissipation plate and contacts the module case, and the thickness of the heat dissipation plate is 0.1 to 2 mm.

At least one or more unit cells are accommodated in the space defined by the heat sink, and the connection between the unit cells and between the unit cells and the external terminals is preliminarily connected to the outside and then inserted into the module case.

The outer casing of the unit cell may be composed of an inner resin layer, a barrier metal layer and an outer resin layer which are thermally fused, or may be composed of only an inner resin layer and an outer resin layer which are thermally fused.

The electrode terminals of the unit cell are formed in one direction or both directions, and the electrode terminals are electrically connected in series or in parallel on one or two surfaces of the battery module.

The module case is made of a metal material, and the heat dissipation unit is made of a metal material or a carbon material.

The module case is opened at least on one side so that the unit cell is housed, and the opened part is sealed by the case cover.

The present invention also provides a lithium secondary battery pack including the battery module as described above.

The battery pack may be used as a power source for a middle- or large-sized device, and the middle- or large-sized device may include a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Cart; Electric truck; Electric commercial vehicles or systems for power storage.

The present invention can effectively remove heat generated during charging and discharging through a simple structure by inserting the unit cells in the module case and the heat dissipating unit in contact with the module case to improve the external impact property of the pouch- And the battery module can be manufactured in a very compact structure, thereby increasing the energy density.

Further, since the battery module case is formed in a completely sealed structure, there is an advantage that the metal layer itself, which is an essential component of the existing pouch-type laminate sheet sheathing material, can be excluded.

Further, the connection between the unit cell and the external terminal can be minimized by connecting the unit cell and the external terminal in advance and connecting the unit cell to the module case.

1 is an exploded perspective view of a structure of a battery module according to an embodiment of the present invention;

Hereinafter, preferred embodiments of the battery module and the secondary battery of the present invention will be described in detail.

1, the present invention provides a battery module comprising two or more pouch type unit cells 1 and a module case 10 for housing the unit cells. The module case 10 has a large area surface of the unit cell and one or more heat dissipating plates 21 that are in contact with the module case 10 in the module case 10, And the module case 10 is completely sealed.

Since the unit cells constituting the battery module (particularly, the middle- or large-sized battery module) are constituted by a rechargeable secondary battery, a lot of heat is inevitably generated in the operation process. If such heat is not efficiently removed, And may cause ignition or explosion in some cases.

In order to solve such a problem, in a general battery module, unit cells are stacked in a state of being spaced apart by a predetermined distance in order to form a heat exchange medium flow path, air is flowed ('air-cooled' By including additional thermally conductive members on the sides of the cells, overheating of the unit cells is prevented.

However, the air cooling type cooling does not actually exhibit a sufficient heat radiation effect, and it is necessary to secure a separate flow channel, which is one of the factors causing the increase of the size of the battery module. On the other hand, when the additional thermally conductive member is separately included in the side faces of the stacked unit cells, the entire battery module becomes bulky and heavy, and the structure becomes complicated, thereby failing to meet the current trend of the industry pursuing miniaturization and lightening of the battery.

Accordingly, the module case 10 may include at least one heat-radiating plate, which is in contact with the large-area surface of the unit cell and the module case 10, so that the module case 10 itself can perform a heat- The heat-conducting heat-dissipating unit 20 is inserted. That is, the module case 10 according to the present invention has a hexahedron shape in which a left side face and a right side face of the module case 10, or only one of them, is opened to insert a cell into the module case 10, And a thermally conductive heat-dissipating unit 20 including a heat-radiating plate is interposed to divide the inside of the module case 10 into a plurality of regions.

Accordingly, when the battery is charged / discharged, the heat generated when the ions are intercalated / deintercalated between the cathode active material and the anode active material is primarily absorbed by the heat sink attached to the large-area surface of the unit cell, And is discharged to the outside through the module case 10 which is in close contact with the heat sink. The heat radiating plate is brought into close contact with the large area surface of the unit cell to maximize the contact area and to prevent a space between the heat transfer media from being maximized. When the unit cell and the heat sink are spaced apart from each other, the heat generated in the unit cell can not be smoothly transferred to the heat sink due to the low thermal conductivity of air (about 0.02 W / m · K) .

The heat dissipation unit 20 may further include a support plate 21 which is integrated with the heat dissipation plate 22 to support the heat dissipation plate from below and contacts the module case 10. In this case, the heat transferred from the unit cell to the heat sink is transmitted to the support plate 21 and finally discharged to the outside through the module case 10 which is in contact with the support plate 21.

According to the present invention, there is no need to additionally provide a separate heat radiating member outside the unit cells (or the battery module) stacked as in the prior art, so that it is possible to provide a simple and compact battery module, .

In addition, the heat sink 22, which is in contact with the large-area surface of the unit cell of the present invention, performs a heat radiating function and also acts as a structure for supporting an external force applied to the pouch type unit cell. Accordingly, it is possible to supplement the external impact characteristics of a pouch-type battery composed of a laminate sheet covering material including a polymer resin layer and having a weaker external force than a cylindrical or prismatic battery with only one component of a simple structure.

In the present invention, the unit cell is not particularly limited as long as it is a rechargeable secondary battery. For example, a lithium secondary battery, a nickel-hydrogen (Ni-MH) secondary battery, and a nickel-cadmium (Ni-Cd) secondary battery may be cited. Among them, .

In addition, the unit cell 1 of the present invention is a pouch type unit cell, and the electrode assembly 1a having a positive electrode / separator / negative electrode structure is embedded in the laminate sheet outer case in a state of being connected to the electrode terminals formed outside the outer case have.

That is, electrode terminals (a positive electrode terminal and a negative electrode terminal) electrically connected to the electrode assembly are protruded from the outside of the unit cell casing. The electrode terminals may protrude only in one direction from the left or right side of the unit cell casing, or may protrude in both directions from both the left and right sides. As a result, the electrode terminals are electrically connected in series or in parallel on one or two surfaces of the hexahedral battery module, and the final positive / negative terminal is connected to the outside of the battery module.

Meanwhile, in the present invention, the electrode terminal protruded to the left side and / or the right side of the casing is described as an example. However, the present invention is not limited thereto and the electrode terminal may be protruded to the upper side and / or the lower side of the casing.

In this case, when the electrode terminals protrude only from one direction of the casing, the module case 10 of the present invention is opened only on one side and both sides of the module case 10 should be opened when the electrode terminals protrude in both directions. FIG. 1 shows an example in which both sides of the module case 10 are opened.

The unit cell shell may include an inner resin layer for thermal fusion, a barrier metal layer, and an outer resin layer for improving durability, as in the conventional case. In the present invention, however, The case 10 itself can perform the function of the conventional barrier metal layer, which is advantageous in that the cell exterior material can be composed of only the inner resin layer and the outer resin layer without omitting the metal layer.

As the heat dissipating unit 20, any material having excellent thermal conductivity can be used without any particular limitation. Preferably, the material may be made of a metal material or a carbon material having a higher thermal conductivity and mechanical strength than those materials having different thermal conductivity and mechanical strength. More preferably, by adopting a material having high thermal conductivity and low mechanical strength while having low electrical conductivity, it is possible to improve the electrical safety of the battery module by improving the insulation property while maintaining high heat dissipation characteristics and external impact characteristics.

In addition, in the present invention, the heat dissipation unit 20 and the module case 10 are in contact with each other and perform a heat dissipation function as a whole, so that they are both made of a heat conductive material such as a metal. Preferably, it is formed of a thermally conductive material of the same material so that uniform heat transfer is achieved while passing through the heat dissipation unit 20 and the module case 10. [ The heat dissipating unit 20 and the module case 10 may be made of any metal or carbon material. However, it is preferable that the heat dissipating unit 20 and the module case 10 are made of SUS series or Al series, considering heat conductive workability and weldability.

On the other hand, if the size of the heat dissipation unit 20 is too large, the volume and weight of the battery module will increase, and if it is too small, the heat dissipation characteristics will deteriorate. Accordingly, it is preferable that the size of the heat dissipation unit 20 is formed to an appropriate size to effectively absorb and discharge the heat of the unit cells. Therefore, the thickness of the heat sink 22 is preferably about 0.1 to 2 mm in consideration of the heat radiation efficiency and the capacity of the battery. That is, when the thickness of the heat sink is less than 0.1 mm, the heat dissipation characteristics may be deteriorated. If the thickness is more than 2 mm, the volume of the battery module may be increased. In addition, it is advantageous to prevent the heat radiating plate 22 from short-circuiting with the electrode terminal protruding from the unit cell when the heat radiating plate 22 is equal to or smaller than the area of the electrode plate constituting the unit cell. Further, the shape of the heat radiating plate is not limited as long as the heat of the unit cells can be smoothly discharged and the inside of the module case can be divided.

The pouch-type unit cells 1 may be accommodated in one or more spaces defined by the heat sink 22. Preferably, only one unit cell is accommodated in a space defined by the heat sink, so that heat generated in each unit cell is quickly removed, and only a specific unit cell is overheated to prevent a temperature deviation between unit cells from occurring do.

On the other hand, the module case 10 according to the present invention is characterized by being completely sealed. That is, the case cover 60 is coupled to the opened portion of the module case 10, and then sealed using welding or the like. As a result, the module case 10 itself, which is a member for secondary packaging, is completely sealed in the pouch type unit cell made of the electrode assembly housed in the laminate sheet sheathing material.

As a result, it is possible to exclude a metal layer such as aluminum, which is essentially contained in the laminate sheet outer cover material, as a barrier layer for preventing moisture and gas from flowing into or out of the electrode assembly.

In other words, since the module case 10 itself acts as a barrier layer of water and gas, the conventional expensive laminate sheet outer material can be replaced with an inexpensive polymeric resin film, and the unit cell can be manufactured lightly. In addition, it is possible to fundamentally prevent foreign matter such as moisture from permeating into the battery module from the outside of the battery module.

In the present invention, the connections between the unit cells and the unit cells and the external terminals may be connected to the module case 10 after they are connected to the outside in advance.

Specifically, before the unit cell is inserted into the module case 10, electrical connections between the electrode terminals of the unit cell and the unit cell and the external terminal are made in advance, and then the module case 10 is inserted into the module case 10 Additional parts for electrical fastening of the terminals need not be welded, so that the welding sealing surface of the outer can can be minimized.

Meanwhile, the surface including the terminal connected to the outside of the module case 10 may be composed of one assembly part.

When a large-sized battery module is constructed by using a plurality of unit cells, a large number of members are generally required for mechanical fastening and electrical connection thereof, so that the process of assembling such members is very complicated. Furthermore, a space is required for the joining of a plurality of members for mechanical fastening and electrical connection, welding, soldering, and the like, thereby increasing the overall size of the system. Such an increase in size is undesirable from the viewpoint of the space limitations of devices or devices in which the middle- or large-sized battery module is mounted, and in order to efficiently mount the middle- or large-sized battery module in a limited internal space such as a vehicle, a middle- or large- sized battery module with a more compact structure is required.

Specifically, in order to solve the above problem, connection between pouch type unit cells and pouch type unit cells housed in the module case 10 and external terminals can be made by one assembly part. That is, between the module case 10 and the case lid 60, a connection member 30 connected to an electrode terminal of each unit cell is interposed. If the unit cells are inserted into the module case 10 and the connection between the unit cells and the connection with the external terminals are made through the single connection member 30 already coupled, the conventional cumbersome mechanical fastening and electrical connection The operation can be performed very easily.

A bus bar 40 is provided between the connection member 30 and the case lid 60 so that the electrode terminals are connected in series or parallel to each other and an insulating gasket for insulation between the connection member 30 and the case lid 60 50 are interposed.

The present invention also relates to a lithium secondary battery pack including the battery module.

Particularly, it is preferable that the battery pack according to the present invention is used as a power source of a middle- or large-sized device. In the case of a middle- or large-sized battery pack, a plurality of unit cells are stacked and used in order to secure a high output and a large capacity. Battery modules constituting such a battery pack are required to have higher heat dissipation efficiency in order to secure safety.

Specific examples of the medium and large-sized devices include a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Cart; Electric truck; An electric commercial vehicle or a system for electric power storage.

The specific structure and manufacturing method of the middle- or large-sized battery pack are well known in the art, and a description thereof will be omitted in this specification.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example  One

The inner resin layer (polyethylene film), the metal layer (Al), and the outer resin layer (nylon film) were laminated to produce eight laminate sheet outer cover materials, and then the inner bottom portions were formed by deep drawing on the bottom outer cover material.

Next, four stacked electrode assemblies were housed in the dry room in such a manner that the electrode terminals were formed on both sides of the casing in both directions, and 1M LiPF ₆ carbonate electrolyte was injected. Then, the upper surface facings were covered and then the four outer peripheries were opened And four pouch type unit cells were produced by fusion bonding.

Next, three heat sinks (thickness: 0.5 mm) and Al Unified A heat dissipation unit was fabricated, and the four unit cells thus fabricated were stacked one by one between the heat dissipation plates so that their large-area faces closely contacted with the heat dissipation plates.

Next, before the module case is inserted, the unit cells and the unit cells and the external terminals are electrically connected in advance using bus bars and connection members for external connection.

Next, the unit cell / heat sink unit assembly Made of material The module case was inserted into the module case, and the support plate of the heat dissipation unit was tightly fitted to both the lower surface and both side surfaces of the module case.

Finally, a battery module having a structure in which the case body and the outer can are welded to completely seal the module case is manufactured.

Example  2

Except that the metal layer (Al) is omitted from the unit cell sheathing material.

Comparative Example

The inner resin layer (polyethylene film), the metal layer (Al), and the outer resin layer (nylon film) were laminated to produce eight laminate sheet outer cover materials, and then the inner bottom portions were formed by deep drawing on the bottom outer cover material.

Next, four stacked electrode assemblies were housed in the dry room in such a manner that the electrode terminals were formed on both sides of the casing in both directions, and 1M LiPF ₆ carbonate electrolyte was injected. Then, the upper surface facings were covered and then the four outer peripheries were opened And four pouch type unit cells were produced by fusion bonding.

Next, Al The four unit cells were housed in the module case of the same size as Example 1, with the same distance from each other, so that an air flow path was formed.

Next, the electrode terminals of the four unit cells are electrically connected to each other using a bus bar, and then the external connection terminal is coupled to the bus bar so that the bus bar is finally connected to the external terminal. At this time, the module case was not a completely sealed structure.)

Experimental Example

The battery module manufactured in the above Examples and Comparative Examples were fully charged at a rate of 1 C-rate, and after waiting for a sufficient time to allow the internal temperature of the battery to become equal to each other, charging and discharging were performed under the condition of full charge at a current of 2 C- The average temperature change of the unit cells was measured with time (in the case of the comparative example, the air was flown into the spaced space to conduct heat radiation).

Average temperature of four unit cells (° C) Time (min) Example 1 Example 2 Comparative Example 0 (discharge start) 25 25 25 10 26 26 28 20 29 28 32 30 (discharge completed) 34 32 40 40 29 29 32 60 25 25 27

As shown in Table 1, by inserting a large-area surface of the unit cell and a heat-dissipating unit in contact with the module case in the module case, the heat radiation characteristic is superior to that of the comparative example and the temperature inside the cell can be uniformly controlled Able to know. That is, it has been confirmed that the heat generated in the unit cell can be effectively discharged to the outside by a simple structure, and ultimately, the lifetime and safety of the battery can be greatly improved.

Further, as a result of the fact that the module case is completely sealed, water and gas barrier properties are ensured even when the metal layer is omitted in the case of the laminate sheet of the pouch type battery, while in the comparative example, the module case is sealed A barrier metal layer is necessarily required.

In addition, in the embodiment, since the connection between the unit cells and the unit cells and the external terminals are preliminarily connected and connected to the outside after being connected to the module case, the welding sealing surface of the outer can is reduced.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. The scope of the present invention is defined by the appended claims rather than by the foregoing description and is not intended to limit the scope of the present invention. And the like are to be construed as falling within the scope of the present invention.

10; Module case
20; Heat-dissipating unit
21; Support plate
22; Heat sink
30; Connecting member
40; Bus bar
50; Insulated gasket
60; Case cover

Claims (15)

1. A battery module comprising two or more pouch-shaped unit cells and a module case for housing the unit cells,
Wherein the module case includes a resin layer and integrally formed therein, a thermally conductive heat dissipating unit including at least one heat dissipating plate which is in contact with a large-area surface of the unit cell and the module case,
Wherein the heat dissipation unit further includes a support plate that is integrated with the heat dissipation plate to support the heat dissipation plate and contacts the module case.
The method according to claim 1,
Wherein at least one of the unit cells is accommodated in a space defined by the heat sink.
The method according to claim 1,
Wherein the thickness of the heat sink is 0.1 to 2 mm.
The method according to claim 1,
Wherein the connection between the unit cells and between the unit cells and the external terminals is preliminarily connected externally and then inserted into the module case.
The method according to claim 1,
Wherein the outer casing of the unit cell comprises an inner resin layer, a barrier metal layer, and an outer resin layer which are thermally fused.
The method according to claim 1,
Wherein the outer shell of the unit cell comprises only an inner resin layer and an outer resin layer which are thermally fused.
The method according to claim 1,
Wherein the electrode terminals of the unit cells are formed in one or both directions.
8. The method of claim 7,
And the electrode terminals are electrically connected in series or in parallel on one or both surfaces of the battery module.
The method according to claim 1,
Wherein the module case is made of a metal material.
The method according to claim 1,
Wherein the heat dissipation unit is made of a metal material or a carbon material.
The method according to claim 1,
Wherein the module case is opened at least on one side so as to receive the unit cell, and the opened part is sealed by the case cover.
A lithium secondary battery pack comprising the battery module according to any one of claims 1 to 11.
13. The method of claim 12,
Wherein the battery pack is used as a power source for a middle- or large-sized device.
14. The method of claim 13,
The middle- or large-sized device includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Cart; Electric truck; An electric commercial vehicle or a system for electric power storage.
delete

Images