KR20120048937A - Battery module and lithium secondary battery pack comprising the same - Google Patents

Abstract

PURPOSE: A battery module and a lithium secondary battery pack including thereof are provided to effectively remove heat generated during charging and discharging by forming a heat-radiant member and a module case into one body, thereby enhancing external shock property of a pouched type battery. CONSTITUTION: A battery module comprises a unit cell including a cell external material, positive electrode built in the cell external material/ a separator/a cathode assembly, and an electrode terminal which is formed outside of the cell external material in order to electrically connect, and a module case(10) which the unit cell is accepted. Inside of the module case is comparted as thermal conductance heat-sinking members(20) into one body. At least one of the unit cell is accepted in the space comparted by the heat-sinking members. At least one side of the module case is opened so that the unit cell can be accepted. The opened part is sealed up by a sealing panel(40).

Description

BATTERY MODULE AND LITHIUM SECONDARY BATTERY PACK COMPRISING THE SAME}

The present invention relates to a battery module having improved heat dissipation and a lithium secondary battery pack including the same.

Due to the development of technology and increasing demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries with high energy density, high operating voltage and excellent life characteristics are energy sources for various mobile devices as well as various electronic products. Widely used. In addition, the lithium secondary battery has attracted great attention as an energy source for electric vehicles and hybrid electric vehicles, which are proposed as alternatives to solve the environmental pollution and global warming problems of conventional gasoline and diesel vehicles that use fossil fuels. Are in the process of being commercialized.

In medium and large devices such as electric vehicles and hybrid electric vehicles, battery modules in which a plurality of unit cells are electrically connected due to the need for high output and large capacity are used. Since the size and weight of the battery module are directly related to the accommodation space and output of the medium and large devices, manufacturers are trying to manufacture a battery module capable of miniaturization and light weight while ensuring high output.

On the other hand, secondary batteries are classified into cylindrical batteries, rectangular batteries and pouch-type batteries according to the external and internal structural characteristics, and among them, pouch-type batteries that can be stacked with a high degree of integration, have a small width to length, and are light in weight are of particular interest. I am getting it.

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

In other words, stacking a plurality of unit cells has a high degree of charge, but it is difficult to remove the heat generated during charging and discharging, and if the heat dissipation is not properly achieved and accumulates, the battery deteriorates and the life is not only reduced. Safety can be greatly compromised. In particular, a battery that requires high-speed charging and discharging characteristics, such as a power source of an electric vehicle or a hybrid electric vehicle, requires a lot of heat generation in the process of providing high power instantaneously, so the need for effective heat dissipation is greater.

The laminate sheet exterior material of the pouch type battery widely used in the battery module includes a polymer resin layer, unlike the rectangular battery. Most of the polymer resin layer materials have a low thermal conductivity, so that heat generated inside the battery can be quickly released to the outside. It is not vulnerable to external shocks and requires additional components to ensure safety.

In addition, the pouch-type battery includes a metal layer such as aluminum (Al) in the laminate sheet to block water and gas, and the metal layer requires an expensive material as compared to the polymer resin layer, thereby increasing the overall manufacturing cost of the battery. There is this.

In this regard, Japanese Patent Application Laid-Open No. 2001-297741 uses a metal heat collecting plate having excellent thermal conductivity between each battery, and connects a heat pipe attached to the heat collecting plate with a heat radiating member provided on the outer surface of the battery pack case. To disclose a structure for releasing heat inside a battery pack.

However, since the cross-sectional area of the portion connecting the heat pipe and the heat dissipation member is small, the battery pack of the above structure does not efficiently transfer heat inside the battery pack case to the heat dissipation member. Is complicated and takes up a lot of space.

Therefore, it is time to develop a battery module capable of exhibiting excellent heat dissipation characteristics through a simple structure, improving external impact characteristics, and excluding a metal layer from a laminate sheet exterior material of a conventional pouch type battery.

The present invention has been made to solve the above-mentioned problems of the prior art, and a battery module, characterized in that the module case is completely sealed and included in a state in which the heat conductive heat dissipation member is integrated inside the battery module case and In this case, it is possible to effectively remove the heat generated from the unit cells through a simple structure and to replace the expensive laminate sheet packaging material containing a metal layer with only a low-cost polymer resin film.

In order to solve the above problems, in the present invention, a unit including a cell packaging material, an electrode assembly having a cathode / separator / cathode structure embedded in the cell packaging material, an electrode terminal formed on the outside of the cell packaging material to be electrically connected to the electrode assembly. Cell; The unit cell is accommodated, and a battery module including a module case which is partitioned in a state in which a thermally conductive heat dissipation member is integrated to remove heat generated from the unit cell is provided.

At least one unit cell is accommodated in a space partitioned by the heat dissipation member.

At least one surface of the module case is opened to accommodate the unit cell, and the opened portion is sealed by a sealing panel.

The battery module includes a terminal assembly for the electrical connection between the unit cell and the unit cell and between the unit cell and the external terminal, the terminal assembly is an assembly body fixedly coupled to the module case to be connected to the electrode terminal of the unit cell; It includes an input and output terminal protruding on one side of the assembly body to be electrically connected to the unit cell.

The terminal assembly is welded to the module case for sealing the module case.

The cell packaging material may include an inner resin layer and an outer resin layer that are thermally fused, and a metal layer may be further included between the inner resin layer and the outer resin layer.

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

The heat dissipation member and the unit cell are disposed to contact each other.

The heat dissipation member and the module case are made of a thermally conductive material of the same material, in particular, the heat dissipation member and the module case is made of a metal or carbon material.

In addition, the present invention provides a lithium secondary battery pack including the battery module described above.

The battery pack is used as a power source for a medium and large device, and the medium and large device includes a power tool; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); Electric two-wheeled vehicles including E-bikes and E-scooters; Electric Golf Carts; Electric trucks; Electric commercial vehicles or power storage systems are applied.

The present invention has an advantage that by integrating the heat dissipation member and the module case, it is possible to effectively remove the heat generated during charging and discharging through a simple structure, and to improve the external impact characteristics of the pouch-type battery.

In addition, by forming the battery module case in a completely sealed structure, there is an advantage that can be excluded the metal layer itself, which is an essential component of the existing pouch-type laminate sheet packaging material.

In addition, there is an advantage in the battery module can simplify the conventional complex mechanical fastening and electrical connection work.

1 is an exploded perspective view showing 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.

As shown in FIG. 1, a battery module according to the present invention includes two or more pouch-type unit cells and a module case for accommodating the pouch-type unit cells, wherein the pouch-type unit cell is a cell exterior material of a laminate sheet. An electrode assembly having a cathode / separation membrane / cathode structure is embedded in a state connected to electrode terminals formed outside of the cell exterior material, and a thermally conductive heat dissipation member is integrated in the module case to charge the battery module. When discharging, the module case itself may remove heat generated from the pouch-type unit cell, and the module case may be completely sealed.

Since the unit cells constituting the battery module (especially the medium-large battery module) are composed of secondary batteries capable of charging and discharging, inevitably a lot of heat is generated during the operation process, the unit cell deterioration if such heat is not removed efficiently And in some cases may ignite or explode.

In order to solve this problem, a general battery module is configured by stacking unit cells spaced apart by a predetermined distance to form a heat exchange medium flow path, and flows air ('air-cooled') to such spaces, or adds a heat sink. By including a thermally conductive member, overheating of the unit cells is prevented.

However, the air-cooled cooling is in fact not exhibiting sufficient heat dissipation effect, and since it is necessary to secure a separate flow path, it becomes one of the factors causing an increase in the size of the battery module. On the other hand, if the additional thermally conductive member is included separately, the volume and weight of the entire battery module are increased, and the structure is also complicated, so that it does not meet the current trend of the industry in pursuit of miniaturization and light weight of the battery.

Thus, the present invention includes the thermally conductive heat dissipation member 20 in an integrated state in the module case 10 so that the module case 10 itself can perform a heat dissipation function. That is, the module case 10 applied to the present invention has a hexahedron shape in which only one of the upper and lower surfaces or only one surface thereof is opened in order to inject a cell into the interior thereof, and a plurality of thermoelectrics are formed at predetermined intervals therein. The conductive heat dissipation member 20 is interposed to partition the inside of the module case 10 into a plurality of regions.

Therefore, the heat conductive heat dissipation member 20 absorbs heat generated when ions are occluded / discharged between the positive electrode active material and the negative electrode active material during charge and discharge of the battery, and the heat absorbed in this way is the heat conductive heat dissipation member 20. It is discharged to the outside through the module case 10 connected integrally with. According to the present invention does not need to add a separate member as in the prior art, it is possible to provide a battery module of a simple and compact structure.

In addition, the heat dissipation member 20 in the present invention is disposed between the unit cells (S) to perform a heat dissipation function and at the same time serves as a structure to prevent the external force applied to the pouch-type unit cell. Therefore, the external shock characteristics of the pouch-type battery having a weaker external force than the cylindrical to square battery, which is composed of the laminate sheet exterior material including the polymer resin layer, may be supplemented by only one component of the module case 10 having a simple structure.

In the present invention, the unit cell is not particularly limited as long as it is a secondary battery capable of charging and discharging. For example, a lithium secondary battery, a nickel-hydrogen (Ni-MH) secondary battery, a nickel-cadmium (Ni-Cd) secondary battery, etc. may be mentioned. Among them, a lithium secondary battery that provides a high output by weight is preferably used. Can be.

In addition, the unit cell in the present invention is a pouch-type unit cell, the electrode assembly of the anode / separator / cathode structure is embedded in the cell packaging material of the laminate sheet connected to the electrode terminals formed to the outside of the cell packaging material.

That is, electrode terminals (anode terminals and cathode terminals) electrically connected to the electrode assembly protrude to the outside of the cell packaging material. The electrode terminals may protrude in one direction only from the upper side or the lower side of the cell packaging material in the drawing, or protrude in both directions from both the upper side and the lower side. Specifically, the electrode terminals are electrically connected in series or in parallel on one or two surfaces of the hexahedron battery module, and the final positive / cathode terminals are connected to the outside of the battery module. Meanwhile, in the present invention, the state in which the electrode terminals protrude to the upper side and / or the lower side of the exterior member is described as an example, but the present invention is not limited thereto, and the electrode terminals may protrude to the left side and / or the right side of the exterior member. .

The cell shell member may include all of an inner resin layer for thermal fusion, a barrier metal layer, and an outer resin layer for improving durability, as in a conventional case, but in the present invention, as described below, a fully sealed module case 10 ) Itself can perform the role of the conventional barrier metal layer, there is an advantage that can be composed of only the inner resin layer and the outer resin layer without the metal layer in the cell packaging material.

In the present invention, the heat conductive heat dissipation member 20 is located inside the module case 10 and is integrated with the module case 10.

The heat dissipation member 20 may be integrally manufactured as a part constituting the module case 10 since the first time the module case 10 is manufactured, and once the module case 10 is manufactured, the heat dissipation member 20 is inserted. Next, the module case 10 may be integrated with a welding method.

As the heat radiating member 20, any material having excellent thermal conductivity may be used without particular limitation. Preferably, the thermal conductivity and mechanical strength may be made of a metal or carbon material that is higher than other materials. More preferably, by adopting a material with high thermal conductivity and low mechanical conductivity, heat dissipation characteristics and external impact characteristics may be maintained, and insulation may be improved to improve electrical safety of the battery module.

In addition, in the present invention, since the heat dissipation member 20 and the module case 10 are integrated to perform a heat dissipation function, both of the heat dissipation member 20 and the module case 10 should be heat conductive materials. Preferably, it is formed of a thermally conductive material of the same material to ensure uniform heat transfer across both members. The heat dissipation member 20 and the module case 10 may be made of any metal or carbon material. However, in consideration of thermal conductivity, processability, and weldability, SUS series or Al series may be used.

On the other hand, the heat dissipation member is not limited to its shape, such as plate-shaped, mesh-type, as long as it can smoothly discharge the heat of the unit cells and partition the inside of the module case. In addition, if the size of the heat dissipation member 20 is too large, the volume and weight of the battery module increases, and if it is too small, the heat dissipation characteristics are deteriorated. Therefore, the size of the heat dissipation member 20 is preferably formed to an appropriate size that can effectively absorb and discharge the heat of the unit cells.

One or more pouch-type unit cells may be stored in a space partitioned by the heat dissipation member 20. Preferably, by storing only one unit cell in a space partitioned by the heat dissipation member 20, the heat generated from each unit cell is quickly removed, and only specific unit cells are overheated to generate temperature deviations between the unit cells. To prevent it.

In addition, the pouch-type unit cell is preferably accommodated in contact with the heat dissipation member 20 in view of improving the heat dissipation effect. If the unit cell and the heat dissipation member 20 are excessively spaced apart, the volume of the battery module increases, and the heat generated inside the unit cell is smoothly flowed out due to the low thermal conductivity of the air (about 0.02 W / m · K). It may not be delivered.

On the other hand, the module case 10 in the present invention is characterized in that it is completely sealed. That is, the sealing panel 40 is welded to the opening of the upper or lower portion of the module case 10, which is a member that serves to secondaryly package the pouch-type unit cell made of the electrode assembly accommodated in the laminate sheet exterior material. This is to seal completely. The sealing panel 40 will be described in more detail below.

As a result, as a barrier layer for preventing inflow or outflow of water and gas into the electrode assembly, a metal layer such as aluminum, which is essentially included in the laminate sheet exterior material, can be excluded.

That is, the module case 10 itself serves as a barrier layer for water and gas, thereby replacing the conventional expensive laminate sheet exterior material with a low-cost polymer resin film, and can also be manufactured lightly. In addition, it is possible to fundamentally prevent foreign matters such as moisture from penetrating into the battery module from the outside.

In the case of constructing a medium-large battery module using a plurality of unit cells, a process of assembling these members is very complicated because many members are generally required for their mechanical fastening and electrical connection. Moreover, space is required for joining, welding, soldering, etc. a plurality of members for mechanical fastening and electrical connection, thereby increasing the size of the entire system. This increase in size is not desirable in view of the space limitation of the device or device in which the medium and large battery modules are mounted, and a medium and large battery module having a more compact structure is required to be efficiently mounted in a limited internal space such as a vehicle.

Therefore, in the present invention, one terminal assembly 30 may be coupled to the upper side of the module case 10 so as to be connected to an external terminal.

Specifically, in order to solve the above problem, the connection between the pouch-type unit cell and the pouch-type unit cell and the external terminal accommodated in the module case 10 is made by one terminal assembly 30. Inserting the unit cells into the body of the module case 10, the connection between the unit cells and the connection to the external terminal is made through a single terminal assembly that is already coupled to perform the conventional cumbersome mechanical fastening and electrical connection work very easily can do. Thus, the terminal assembly 30 has a body that can be seated on the upper surface of the module case 10, one side of the body protrudes the input and output terminal 31 for the connection with the external terminal.

In addition, a separate sealing panel 40 is coupled to an upper side of the terminal assembly 30 and a lower side of the module case 10, and each sealing panel 40 is welded to the module case body and the terminal assembly body. By sealing through it can form a fully sealed module case 10 according to the present invention.

On the other hand, the present invention relates to a lithium secondary battery pack comprising a battery module as described above.

In particular, the battery pack according to the present invention is preferably used as a power source for medium and large devices. In the case of medium and large battery packs, a plurality of unit cells are stacked and used to secure high output and high capacity, because battery modules constituting such battery packs require higher heat dissipation efficiency to secure safety.

Specific examples of the medium-large device include a power tool; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); Electric two-wheeled vehicles including E-bikes and E-scooters; Electric Golf Carts; Electric trucks; Electric commercial vehicles or electric power storage systems.

Since the specific structure and manufacturing method of the medium-large battery pack are known in the art, description thereof will be omitted herein.

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

Example  One

After fabricating a cell packaging material by laminating an inner resin layer (polyethylene film), a metal layer (Al), and an outer resin layer (nylon film), an accommodating part was formed on one side through deep drawing and the other side was bent in the form of a cover. .

Next, four stacked electrode assemblies are housed in the dry cell in such a way that the electrode terminals are formed in one direction, the 1M LiPF ₆ carbonate electrolyte is injected, and the four outer pouches are thermally fused to each other. A mold unit cell was prepared.

to the next, The module case made of Al is provided with a heat dissipation member made of the same material as integrated therein, and the inside of the module case is partitioned into four spaces, and then the four unit cells manufactured are in close contact with the heat dissipation member. (The electrode terminals of the four unit cells were stored in the same direction so as to protrude only from one side of the hexahedron battery module.)

Next, one terminal assembly is manufactured so that the received unit cells and the unit cells and the external terminals are connected at once. At this time, the terminal assembly is formed with a terminal hole into which the electrode terminals of all the unit cells can be inserted, and the electrode terminals of the inserted unit cells are connected in series or in parallel by fastening with a bus bar (not shown) that is already configured in the terminal assembly. The bus bar is also connected to the input / output terminals protruding out of the terminal assembly. Thereafter, the terminal assembly was coupled to a portion where the electrode terminals were formed, and then welded to the case body to manufacture a battery module having a completely sealed module case.

Example  2

Except for removing the metal layer (Al) in the cell packaging material is the same as in Example 1.

Comparative example

After fabricating a cell packaging material by laminating an inner resin layer (polyethylene film), a metal layer (Al), and an outer resin layer (nylon film), an accommodating part was formed on one side through deep drawing and the other side was bent in the form of a cover. .

Next, four stacked electrode assemblies are housed in the dry cell in such a way that the electrode terminals are formed in one direction, the 1M LiPF ₆ carbonate electrolyte is injected, and the four outer pouches are thermally fused to each other. A mold unit cell was prepared.

Next, the four unit cells manufactured above were housed in the module case of the same size as that of the first embodiment of Al and spaced apart by the same distance to form an air flow path.

Next, after electrically connecting each of the electrode terminals of the four unit cells using a bus bar, the bus bar was finally connected to an external input / output terminal, thereby manufacturing a battery module. It wasn't a structure.)

Experimental Example

After fully charging the battery modules manufactured in the above Examples and Comparative Examples with 1 C-rate and waiting for a sufficient time for the internal temperature of the cells to be the same, charging and discharging were performed under conditions that were fully discharged with a current of 2 C-rate. The average temperature change of the unit cells was measured over time with the start of discharging. (In the case of the comparative example, heat was radiated by flowing air into the space.)

Average temperature (℃) of 4 unit cells Time (min) Example 1 Example 2 Comparative example 0 (start discharge) 25 25 25 10 26 26 28 20 28 27 30 30 (discharge complete) 32 30 37 40 29 28 31 60 25 25 26

As shown in Table 1, in the case of the embodiment it can be seen that by including a heat dissipation member integrated with the module case exhibits excellent heat dissipation characteristics than the comparative example and can uniformly control the temperature inside the cell. That is, it was confirmed that only a simple structure can effectively release heat generated in the unit cell to the outside, thereby ultimately improving battery life and safety.

In addition, the present invention as a result of the module case is completely sealed, even if the metal layer is excluded in the laminate sheet exterior material of the pouch-type battery (Example 2), water and gas barrier properties are guaranteed, whereas in the comparative example the module case is sealed There is no barrier metal layer necessarily.

In addition, in the embodiment, since the connection between the unit cells and the unit cell and the external terminal is made at one time through a terminal formed of one assembly component, the workability is superior to that of the comparative example in which the electrical connection is performed individually and sequentially.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, the protection scope of the present invention should be interpreted by the following claims, and all the technologies within the equivalent range The spirit will be construed as being included in the scope of the invention.

10; Module case
20; Heat dissipation member
30; Terminal assembly
31; I / O terminal
40; Sealing panel
S; Cell

Claims (16)

A unit cell including a cell sheathing material, an electrode assembly having a cathode / separation membrane / cathode structure embedded in the cell sheathing material, and an electrode terminal formed on an exterior of the cell sheathing material so as to be electrically connected to the electrode assembly;
The unit cell is accommodated, the battery module, characterized in that it comprises a module case partitioned in a state in which the thermally conductive heat dissipation member is integrated.
The method of claim 1,
And at least one unit cell is accommodated in a space partitioned by the heat dissipation member.
The method of claim 1,
The module case is at least one surface is opened so that the unit cell is accommodated, the battery module, characterized in that the opening is sealed by a sealing panel.
The method of claim 1,
The battery module comprises a terminal assembly for the electrical connection between the unit cell and the unit cell and between the unit cell and the external terminal.
The method of claim 4, wherein
The terminal assembly includes an assembly body fixedly coupled to the module case so as to be connected to the electrode terminal of the unit cell, and an input / output terminal protruding on one side of the assembly body to be electrically connected to the unit cell.
The method according to claim 5,
Battery module characterized in that the terminal assembly is welded to the module case for sealing the module case.
The method of claim 1,
The cell packaging material includes a battery module, characterized in that it comprises an inner resin layer and an outer resin layer that is heat-sealed.
The method of claim 7, wherein
The cell packaging material further comprises a metal layer between the inner resin layer and the outer resin layer.
The method of claim 1,
The electrode terminal is a battery module, characterized in that formed in one direction or both directions.
The method of claim 1,
The electrode terminal is a battery module, characterized in that the electrical connection in series or in parallel on one or two sides of the battery module.
The method of claim 1,
And the heat dissipation member and the unit cell are disposed to contact each other.
The method of claim 1,
The heat dissipation member and the module case is a battery module, characterized in that made of a thermally conductive material of the same material.
The method of claim 1,
The heat dissipation member and the module case is a battery module, characterized in that made of metal or carbon material.
A lithium secondary battery pack comprising a battery module according to any one of claims 1 to 13.
The method of claim 14,
The battery pack is a lithium secondary battery pack, characterized in that used as a power source for medium and large devices.
16. The method of claim 15,
The medium-to-large size device includes a power tool; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); Electric two-wheeled vehicles including E-bikes and E-scooters; Electric Golf Carts; Electric trucks; Lithium secondary battery pack, characterized in that the electric commercial vehicle or power storage system.

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