KR20120017613A - Battery module assembly having improved cooling efficiency and battery pack comprising the same - Google Patents

Abstract

PURPOSE: A battery module assembly is provided to improve cooling efficiency by reducing the deviation between battery cells in relative to the existing structure of refrigerant path, thereby maximizing life time and power. CONSTITUTION: A battery module assembly comprises two or more battery modules electrically connecting battery cells and unit modules. The battery modules are arranged to the structure a coolant is continuously progressed to a coolant flow channel of a second battery module near a first battery module, through the coolant flow channel of first battery module for connecting coolant flow channel(50) from each battery module. The cross sectional area of the coolant flow channel in the second battery module(S2) is smaller than the cross sectional area of the coolant flow channel in the first battery module(S1) on the basis of the progressive direction of the coolant, so that the flow of the coolant passing the coolant flow channel of the second coolant(V2) is faster than the flow of the coolant passing the coolant flow channel of the first coolant(V1).

Description

Battery Module Assembly Having Improved Cooling Efficiency and Battery Pack Comprising the Same}

The present invention relates to a battery module assembly having improved cooling performance and a battery pack including the same, and more particularly, to a battery module in which a plurality of battery cells or unit modules (“unit cells”) are electrically connected. It includes two or more, wherein the battery module, the refrigerant flows through the refrigerant passage of the first battery module, so that the refrigerant flow path in each of the battery modules of the second battery module adjacent to the first battery module It is arranged in a structure that proceeds continuously to the refrigerant passage, so that the flow rate (V2) of the refrigerant passing through the refrigerant passage of the second battery module is greater than the flow rate (V1) of the refrigerant passing through the refrigerant passage of the first battery module, The vertical cross-sectional area S2 of the refrigerant passage in the second battery module is smaller than the vertical cross-sectional area S1 of the refrigerant passage in the first battery module based on the traveling direction of the refrigerant. Relates to a battery pack including a battery module assembly, and this.

Recently, secondary batteries have been widely used as energy sources for wireless mobile devices. Secondary batteries are also attracting attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are proposed as a way to solve air pollution in conventional gasoline and diesel vehicles that use fossil fuels. .

In a small mobile device, one or two or more battery cells are used per device, while a middle- or large-sized battery module such as an automobile is used as a middle- or large-sized battery module in which a plurality of battery cells are electrically connected due to the necessity of a large-

Since the medium-large battery module is preferably manufactured in a small size and weight, the rectangular battery, the pouch-type battery, etc., which can be charged with high integration and have a small weight to capacity, are mainly used as battery cells of the medium-large battery module. In particular, a pouch-shaped battery using an aluminum laminate sheet or the like as an exterior member has recently attracted a lot of attention due to its advantages such as small weight, low manufacturing cost, and easy shape deformation.

Since the unit cells constituting the medium-large battery module are composed of secondary batteries capable of charging and discharging, such a high output large capacity secondary battery generates a large amount of heat during the charging and discharging process. If not removed, thermal accumulation occurs and consequently accelerates the deterioration of the unit cell, and in some cases there is also a risk of fire or explosion. Therefore, a high output large capacity battery module or battery pack requires a cooling system for cooling the unit cells embedded therein.

A battery module mounted on a medium-large battery pack is generally manufactured by stacking a plurality of unit cells with high density, and stacking adjacent unit cells at regular intervals so as to remove heat generated during charging and discharging. For example, the battery cells themselves are sequentially stacked while being spaced at predetermined intervals without a separate member, or in the case of battery cells having low mechanical rigidity, one or more combinations are built in a cartridge or the like to form a unit module and the unit A plurality of modules can be stacked to form a battery module.

The flow path of the refrigerant is formed between the unit cells or the battery modules so as to effectively remove heat accumulated between the stacked unit cells or the battery modules.

On the other hand, in the medium-large battery pack composed of a plurality of unit cells, the performance degradation of some unit cells will cause the performance of the entire battery pack. Since one of the main causes of such a performance non-uniformity is due to cooling non-uniformity between unit cells, a structure capable of securing cooling uniformity during the flow of the refrigerant is required.

1 illustrates a battery module assembly, and a portion A schematically illustrates a state in which unit modules are stacked in the battery module.

Referring to FIG. 1, the battery module 100 includes a unit module stack 32 in which a plurality of unit modules 30 are stacked in a lateral direction and electrically connected thereto, and the unit module stack 32 is mounted. The module case 70, a refrigerant inlet 10 through which the refrigerant flows into the battery module 100 from the outside, and a refrigerant discharge port (not shown) through which the refrigerant is discharged from the unit module stack 32.

The coolant flowing from the coolant inlet 10 passes through the flow path 50 formed between the unit modules 30, cools the heat generated in the unit modules 30, and is discharged to the outside through the coolant discharge port. Meanwhile, two battery modules 100 are stacked in the width direction W and the height direction H, respectively, to form the battery module assembly 200.

In the medium-large battery pack according to the prior art, since the battery modules are continuously stacked to form a linear coolant flow path, the coolant gradually increases in temperature while passing through the battery modules, and thus the temperature of the final battery module based on the flow direction of the coolant. There is a problem that causes a temperature deviation between the unit cells than the temperature of the first battery module.

In order to solve this problem, it is possible to consider a method of uniformizing the flow rate and the flow rate of the refrigerant passing through the refrigerant passage, but, as confirmed by the inventors of the present application, the temperature deviation does not decrease despite such an attempt. This is because the length of the flow path through which the refrigerant passes increases due to the laminated structure.

Therefore, there is a high need for a technology capable of fundamentally solving the above problems while maintaining a laminated structure of battery modules.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

After various experiments and in-depth studies on the refrigerant passage, the inventors of the present application maintain the same length of the refrigerant passage in a battery module assembly in which a plurality of battery modules are stacked, while the flow velocity is gradually lowered in the refrigerant passage. As a result of increasing gradually, it was confirmed that the temperature deviation between the unit cells of the upper layer and the lower layer was reduced, and thus, the present invention was completed.

Accordingly, the battery module assembly of the present invention includes a plurality of battery cells or two or more battery modules in which unit modules (“unit cells”) are electrically connected.

The battery modules are arranged in a structure in which the refrigerant flows continuously through the refrigerant passage of the first battery module to the refrigerant passage of the second battery module adjacent to the first battery module so that the refrigerant passage is in communication with each of the battery modules. It is

The refrigerant in the second battery module based on the direction in which the refrigerant flows so that the flow rate V2 of the refrigerant passing through the refrigerant passage of the second battery module is greater than the flow rate V1 of the refrigerant passing through the refrigerant passage of the first battery module. The vertical cross-sectional area S2 of the flow path is smaller than the vertical cross-sectional area S1 of the refrigerant path in the first battery module.

That is, the battery module assembly according to the present invention, by changing only the shape of the flow path while maintaining the overall length of the coolant flow path, the coolant has a faster flow rate while sequentially passing through the battery module, the structure of a conventional straight coolant flow path Compared to the temperature variation between the battery modules, and ultimately, the temperature difference between the battery cells of the battery modules can be reduced, thereby improving the cooling efficiency and thereby maximizing the life and output power.

In the present application, the battery module assembly is not limited to the two-layer stack structure consisting of the first battery module and the second battery module. Therefore, when the battery module assembly includes n battery modules and the battery modules are continuously arranged to communicate with the coolant flow path, the vertical cross-sectional area of the coolant flow path from the first battery module to the nth battery module in the direction of the coolant flow is determined. This may have a structure that gradually decreases.

On the other hand, the greater the vertical cross-sectional area (S1) of the first battery module than the vertical cross-sectional area (S2) of the second battery module, the degree of temperature deviation reduction is further increased.

This is because the speed V2 of the fluid passing through the vertical cross-sectional area S2 of the second battery module increases more than the speed V1 of the fluid passing through the vertical cross-sectional area S1 of the first battery module. In consideration of the cooling efficiency and the dimensions of the battery module assembly as a whole, the vertical cross-sectional area S2 of the second battery module is preferably 30 to 50% of the vertical cross-sectional area S1 of the first battery module.

Specifically, when the vertical cross-sectional area (S2) of the second battery module has a cross-sectional area of more than 50% based on the vertical cross-sectional area (S1) of the first battery module to achieve the temperature uniformity according to the cooling desired in the present invention. It may be difficult, on the contrary, if the size is less than 30%, it is not preferable because the design of the battery module assembly is difficult.

It can be seen in Equation 2 that the heat transfer coefficient h2 of the second battery module is greater than the heat transfer coefficient h1 of the first battery module.

(1)

(One)

Where k, L, V, and C are the thermal conductivity coefficient of the fluid, the representative length of the solid, the density of the fluid, the approaching speed of the fluid, the viscosity of the fluid, and the specific heat of the fluid, respectively. In addition, the three dimensionless numbers, respectively, are Nusselt number ( Nu _L = hL / k ), Reynolds number (Re _L = VL / ), and Plantl number (Pr = C _p / k). Can be defined as Therefore, Equation 1 may be expressed as Equation 2 below.

(2)

(2)

Since heat transfer coefficient is represented by Nu _L in forced convection, such as the flow of the coolant, Nu _L = through the expression of hL / k can be obtained a heat transfer coefficient, the flow rate (V) of the refrigerant in the formula 1 is a Nu _L Is proportional to The heat transfer coefficient h2 of the second battery module is greater than the heat transfer coefficient h1 of the first battery module.

The battery module mounted on the battery module assembly according to the present invention is manufactured by stacking a plurality of unit cells with high density, and stacks adjacent unit cells at regular intervals so as to remove heat generated during charging and discharging. .

When a plurality of unit modules are stacked to form a battery module, a coolant flow path is formed between the unit modules so as to effectively remove heat accumulated between the stacked battery cells.

In one preferred example, the unit cell arrangement interval d1 of the first battery module may have a structure larger than the unit cell arrangement interval d2 of the second battery module. Such a structure satisfies the condition defined above for the vertical cross-sectional areas of the battery modules when the heights of the battery modules are the same. Therefore, not only the shape of the coolant flow path formed between the stacked battery modules is gradually narrowed in the direction of travel of the coolant, but also the coolant flow path gradually narrows in the travel direction of the coolant between the unit cells mounted inside the battery module, thereby reducing the coolant. More contact with the unit cells can further improve the cooling efficiency and equalize the cooling efficiency in the refrigerant passage.

In addition, the battery modules in the battery module assembly may have a structure in which two or more battery modules are arranged in a direction perpendicular to the direction in which the refrigerant flows. Here, "arranged in the vertical direction" means that the battery modules are stacked in a direction perpendicular to the advancing direction of the refrigerant. For example, two of the four battery modules may be arranged in a lower layer and two may be arranged in an upper layer (arranged as “2 × 2”) corresponding to the battery modules arranged in the lower layer.

Also in this case, the direction in which the refrigerant flows is set so that the flow velocity V2 of the refrigerant passing through the refrigerant passage of the lower second battery module is greater than the flow rate V1 of the refrigerant passing through the refrigerant passage of the first battery module of the upper layer. Since the structure in which the vertical cross-sectional area S2 of the refrigerant passage in the second battery module of the lower layer is smaller than the vertical cross-sectional area S1 of the refrigerant passage in the upper layer of the second battery module is still maintained, the inter-cell modules and the unit cells are still maintained. It is possible to equalize the cooling efficiency in the refrigerant passage formed between them.

In one specific example, the battery modules are stacked in the vertical direction so that the coolant flow path is vertically communicated, and the coolant flows in from the coolant inlet located at the top of the battery module assembly and passes through the battery module, and is located at the bottom of the battery module assembly. It may be arranged in a structure that is discharged to the refrigerant outlet.

In this case, the unit cells are also preferably arranged in the lateral direction so that the refrigerant passage is in vertical communication. The refrigerant flows from the refrigerant inlet located above the battery module assembly and passes through the refrigerant passage formed between the battery modules and the refrigerant passage formed between the unit cells, thereby improving cooling efficiency in the refrigerant passage.

In another specific example, the battery modules are stacked such that the coolant flow paths communicate in the left and right directions, and the coolant flows from the coolant inlet located at one side of the battery module assembly and passes through the battery module, and the coolant is located at the opposite side of the battery module assembly. It may be a structure arranged in a structure that is discharged to the outlet.

The present invention also provides a battery pack in which the battery module assembly is mounted in a battery pack case. The coolant inlet and the coolant discharge part are flow spaces through which coolant can be introduced and discharged to effectively cool the generation of heat due to charging and discharging of the unit cells, and are respectively formed at upper and lower portions of the pack case in opposite directions. In some cases. The coolant inlet and the coolant outlet may be formed at the bottom and top of the pack case, respectively.

As used herein, the term “battery module” refers to a structure of a battery system capable of providing high power and high capacity electricity by mechanically coupling two or more charging / discharging unit cells and simultaneously connecting them electrically. This includes all of the cases in which one device or a part of a large device is configured. For example, a large battery module may be configured by connecting a plurality of small battery modules, or a plurality of unit modules may be connected by connecting a small number of battery cells.

On the other hand, the structure of the unit module can be made in a variety of configurations, a preferred example will be described below.

The unit module has a structure in which plate-shaped battery cells having electrode terminals formed at upper and lower ends thereof are interconnected in series and / or parallel, and two or more battery cells having a stacked structure by bending the connection portions of the electrode terminals. And, except for the electrode terminal portion may be configured to include a high-strength cell cover coupled to surround the outer surface of the battery cells.

The plate-shaped battery cell is a battery cell having a thin thickness and a relatively wide width and length so as to minimize the overall size when it is charged for the configuration of the battery module. Such a preferable example may be a secondary battery having a structure in which an electrode assembly is embedded in a battery case of a laminate sheet including a resin layer and a metal layer, and electrode terminals protrude from upper and lower ends thereof, and specifically, a pouch type of an aluminum laminate sheet. It may be a structure in which the electrode assembly is built in the case. A secondary battery having such a structure may be referred to as a pouch type battery cell.

These battery cells can be configured as a unit module in a structure wrapped in a high-strength cell cover made of synthetic resin or metal in two or more units, the high-strength cell cover is charged and discharged while protecting the battery cell with low mechanical rigidity It prevents the sealing part of the battery cell from being separated by suppressing the change of repetitive expansion and contraction during the time. Therefore, it becomes possible to manufacture a medium-large battery module with more excellent safety ultimately.

The battery cells in the unit module or between the module modules are connected in series and / or in parallel, and in a preferred embodiment, the electrode terminals are arranged with the battery cells arranged longitudinally in series so that their electrode terminals are continuously adjacent to each other. After combining, the plurality of unit modules may be manufactured by folding the battery cells in two or more units so as to overlap each other and wrapping the cells in a predetermined unit by the cell cover.

Coupling of the electrode terminals may be implemented in various ways, such as welding, soldering, mechanical fastening, preferably by welding.

The plurality of unit cells, in which electrode terminals are interconnected and filled with high density, may be vertically mounted in a vertically separate case coupled to a prefabricated fastening structure to constitute the rectangular battery module.

More specific details of a unit module and a rectangular battery module manufactured using a plurality of such unit modules are disclosed in Korean Patent Applications Nos. 2006-45443 and 2006-45444 of the present applicant, the contents of which are incorporated by reference. Incorporates the teachings of the present invention.

In addition, the battery pack according to the present invention includes a plurality of unit cells to achieve a high output large capacity, so that the high heat generated during charging and discharging seriously emerge in terms of safety, hybrid electric vehicle, or plug-in hybrid electric It can be used particularly preferably as a power source for automobiles or power storage devices.

As described above, in the battery module assembly according to the present invention, the flow rate V2 of the refrigerant passing through the refrigerant passage of the second battery module is greater than the flow rate V1 of the refrigerant passing through the refrigerant passage of the first battery module. The vertical cross-sectional area S2 of the coolant flow path in the second battery module is smaller than the vertical cross-sectional area S1 of the coolant flow path in the first battery module based on the direction in which the coolant flows. Reduced temperature drift between cells improves cooling efficiency, thus maximizing lifetime and power.

1 is a perspective view schematically showing a state in which battery cells are stacked in a battery module assembly and a battery module;
2 is a schematic diagram of a refrigerant passage according to one embodiment of the present invention;
3 is a schematic view of battery modules stacked in accordance with one embodiment of the present invention;
4 is a schematic view of battery modules stacked in a vertical direction with respect to a traveling direction of a coolant according to another embodiment of the present invention;
FIG. 5 is a vertical sectional view schematically showing a battery pack having a structure in which battery modules are stacked such that coolant passages communicate in a left and right direction according to another exemplary embodiment of the present invention.
6 and 7 are schematic views of unit cells stacked in accordance with another embodiment of the present invention;
8 is a graph showing a result of measuring the temperature change between the upper and lower battery cells in the battery pack according to an embodiment of the present invention;
9 is a graph showing the results of measuring the heat transfer coefficient between the upper and lower battery cells in the battery pack according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

2 schematically shows a coolant flow path according to an embodiment of the present invention, and FIG. 3 schematically shows stacked battery modules according to one embodiment of the present invention. According to still another embodiment of the present invention, battery modules stacked in a vertical direction with respect to a traveling direction of a coolant are schematically illustrated.

Referring to these drawings and FIG. 1, the battery pack 300 includes battery modules 100, 100a and 100b in which a plurality of unit modules 30 or battery cells 31 are electrically connected, and such battery modules ( The pack case 350 in which the 100, 100a, and 100b are mounted, the coolant inlet 310 and the battery modules 100 and 100a which are flow spaces from the coolant inlet 315 to the battery modules 100, 100a and 100b. And a refrigerant discharge part 320 which is a flow space from 100b to the refrigerant discharge port 325.

The refrigerant flowing from the refrigerant inlet 315 passes through the refrigerant inlet 310 and the refrigerant passage 50 formed in the battery modules 100, 100a and 100b, and the unit modules 30, 30a and 30b or the battery cell. The fields 31 and 31a are cooled and discharged to the outside through the coolant discharge part 320 and through the coolant discharge port 325.

The coolant flow path 50 is formed in a shape in which the cross-sectional area S1 closer to the coolant inlet 310 is larger and the cross-sectional area S2 closer to the coolant outlet 320 is gradually smaller. Therefore, the speed V2 near the coolant discharge part 320 becomes larger than the speed V1 near the coolant inlet part 310.

That is, the arrangement interval d1 of the unit modules 30 of the first battery module is greater than the arrangement interval d2 of the unit modules 30a of the second battery module, and the refrigerant passage 50 is formed in the battery module 100. The cross sectional area S1 near the coolant inlet 10 is large and the cross sectional area S2 near the coolant discharge part (not shown) is gradually reduced.

In the battery modules 100, 100a and 100b, the diaphragm 120 is formed such that the refrigerant cannot pass through a path other than the refrigerant path 50.

The battery modules 100, 100a and 100b are also stacked in a direction perpendicular to the traveling direction of the refrigerant. 4 illustrates a state in which the battery modules 100, 100a, and 100b of FIG. 3 are stacked in 2 × 3, and the coolant flow path 50 has a cross-sectional area S1 closer to the coolant inlet 310. The cross-sectional area S2 larger and closer to the refrigerant discharge part 320 is formed in a gradually decreasing shape.

FIG. 5 is a vertical cross-sectional view of a battery pack having a structure in which battery modules are stacked in such a manner that the refrigerant passages communicate with each other in a left and right direction according to another embodiment of the present invention.

In the battery modules 100, 100a and 100b, the cross-sectional area S1 of the unit modules 30, 30a and 30b close to the refrigerant inlet 310 on the right side is large and is provided on the refrigerant discharge unit 320 on the left side. The adjacent cross-sectional area S2 is arranged so that the coolant flow passage 50 having a gradually decreasing shape communicates with the left and right directions, and the coolant is unit modules 30 along the coolant flow passage 50 in which the diaphragm 120 is not formed. , 30a and 30b are cooled and discharged to the outside through the coolant discharge part 320.

6 and 7 show unit cells stacked in accordance with another embodiment of the present invention.

1 and 3 together, the coolant flow path 50 formed between the unit modules 30, 30a and 30b and / or the battery cells 31c and 31d is compared with the cross-sectional area S1 of the upper layer. The cross-sectional area S2 of the lower layer gradually decreases.

That is, the coolant flow path 50 is formed of the unit modules 30, 30a and 30b and / or the battery cells 31c and 31d without forming the diaphragm 120. That is, a plurality of unit modules 30 are spaced apart at a side by a predetermined interval on the top layer, and a plurality of unit modules 30a and 30b and / or battery cells 31c and 31d are spaced apart at a side by a lower layer. Spaced apart.

FIG. 7 illustrates a structure in which the unit modules 30, 30a and 30b and / or the battery cells 31c and 31d are arranged such that the refrigerant passage 50 communicates in the left and right directions.

Referring to FIG. 7, a coolant flow path 50 is formed in a cross-sectional area S1 on the right side through which the coolant flows, and larger than the cross-sectional area S2 on the left side, and a plurality of unit modules 30 are disposed at a predetermined interval on the right side. Spaced apart from each other, and a plurality of unit modules 30a and 30b and / or battery cells 31c and 31d are spaced apart at a predetermined interval on the left side.

8 is a graph showing a result of measuring the temperature change between the battery cells mounted on the upper and lower battery modules in the battery pack according to an embodiment of the present invention, Figure 9 is a battery according to an embodiment of the present invention A graph showing the results of measuring the heat transfer coefficient (h) between the battery cells mounted on the upper and lower battery modules in the pack is shown.

Referring to these graphs together with FIGS. 1 and 3, the temperature and heat transfer coefficients of the battery cells 31 mounted on the battery module 100 in each layer by stacking five battery modules 100 up and down (h) As a result of the measurement, the heat generation amount is 60 W / m ² , the flow rate is 0.03 kg / s, and the length of the flow path is 1000 mm in the conventional straight coolant flow path P under the same experimental conditions. When the temperature was set to 1.00, the temperature gradually increased toward the lower layer, and the lowermost battery cell 31 exceeded 1.10.

On the other hand, in the coolant flow path I of the present invention formed gradually narrower at a width of 3 mm when the temperature of the uppermost battery cell 31 is 1.00, the temperature gradually increased toward the lower layer, but the lowermost battery cell The temperature of (31) showed a value of approximately 1.09.

This indicates that the temperature deviation between the uppermost layer and the lowermost battery cell 31 in the refrigerant passage I of the present invention is reduced by 10% compared to the conventional linear refrigerant passage P. FIG. In addition, when the coolant flows at a flow rate of 0.09 kg / s in the coolant flow passage formed to gradually narrow at 21 mm, the temperature deviation between the uppermost layer and the lowermost battery cell 31 is lower than that of the conventional linear coolant flow passage P. Decreased by 50%.

On the other hand, the heat transfer coefficient is the heat transfer coefficient h2 of the lower battery cell 31 when the heat transfer coefficient h1 of the uppermost battery cell 31 is 1.0 in the conventional straight refrigerant path P. Is similar to or slightly reduced to 1.0, but in the refrigerant passage (I) of the present invention in which the width of the refrigerant passage is gradually narrowed at 3 mm, when the heat transfer coefficient h1 of the battery cell 31 of the uppermost layer is 1.0, The heat transfer coefficient h2 of the lower battery cell 31 gradually increases, and the heat transfer coefficient of the lowermost battery cell 31 shows a value close to 1.6.

Although described with reference to the drawings according to an embodiment of the present invention, those of ordinary skill in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (11)

A plurality of battery cells or unit modules ("unit cells") includes two or more battery modules that are electrically connected,
The battery modules are arranged in a structure in which the refrigerant flows continuously through the refrigerant passage of the first battery module to the refrigerant passage of the second battery module adjacent to the first battery module so that the refrigerant passage is in communication with each of the battery modules. It is
The refrigerant in the second battery module based on the direction in which the refrigerant flows so that the flow rate V2 of the refrigerant passing through the refrigerant passage of the second battery module is greater than the flow rate V1 of the refrigerant passing through the refrigerant passage of the first battery module. The vertical cross-sectional area (S2) of the flow path is a battery module assembly, characterized in that formed in the first battery module smaller than the vertical cross-sectional area (S1) of the refrigerant path. The method of claim 1, wherein when the battery module assembly includes n battery modules and the battery modules are continuously arranged such that the coolant flow paths communicate with each other, the first battery module to the nth battery module based on the moving direction of the coolant are provided. The battery module assembly, characterized in that it has a structure in which the vertical cross-sectional area of the refrigerant passage is sequentially reduced. The method of claim 1, wherein the vertical cross-sectional area (S2) of the second battery module battery module assembly, characterized in that the size of 30 to 50% of the vertical cross-sectional area (S1) of the first battery module. The battery module assembly of claim 1, wherein the heat transfer coefficient (h2) of the second battery module is larger than the heat transfer coefficient (h1) of the first battery module. The battery module assembly of claim 1, wherein the unit cells of the battery module are arranged side by side at intervals forming a refrigerant passage. The battery module assembly of claim 1, wherein the unit cell arrangement interval d1 of the first battery module is greater than the unit cell arrangement interval d2 of the second battery module. The battery module assembly of claim 1, wherein two or more battery modules are arranged in a direction perpendicular to the direction in which the refrigerant flows. The battery module of claim 1, wherein the battery modules are stacked in a vertical direction such that the coolant flow paths communicate vertically, and the coolant flows in from the coolant inlet located at the top of the battery module assembly and passes through the battery module. Battery module assembly, characterized in that arranged in a structure that is discharged to the refrigerant outlet located. The battery module of claim 1, wherein the battery modules are stacked in such a manner that the coolant flow paths communicate with each other in the left and right directions, and the coolant flows in from the coolant inlet located at one side of the battery module assembly and passes through the battery module. Battery module assembly, characterized in that arranged in a structure that is discharged to the refrigerant outlet. A battery pack according to claim 1, wherein the battery module assembly is mounted in a pack case. The battery pack of claim 10, wherein the battery pack is used as a power source for an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.

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