Battery module with heat dissipation and insulation functions and battery pack equipped therewith

Abstract

The battery module of the present invention includes a cell stack (100) and a module case (200) that houses the cell stack, the cell stack including a plurality of battery cells (110) and at least one heat dissipation composite (120) and heat insulation composite (130) interposed between the battery cells, the heat dissipation composite including an insulating coated graphite sheet (121) and a buffer member (122) made of a flame-retardant material laminated on one surface of the graphite sheet, and the heat insulation composite including a vacuum insulation plate (131) having a vacuum space inside and a buffer member (132) made of a flame-retardant material laminated on one surface of the vacuum insulation plate.

Description

Technical Field

[0001] The present invention relates to a battery module, and more particularly, to a battery module having both a heat dissipation function for dissipating heat generated from battery cells and a heat insulation function for blocking heat so as not to spread to other adjacent battery cells during thermal runaway. The present invention also relates to a battery pack including the above battery module.

Background Art

[0002] Generally, a battery module includes a cooling system to prevent the life of the battery module from being rapidly shortened due to temperature during long-term use. Such a cooling system is designed in consideration of the amount of heat generated according to the usage environment of the battery module.

[0003] However, when abnormal heat generation symptoms occur due to a failure of some battery cells during the use process of the battery module, the temperature may continue to rise. In this case, when the critical temperature is exceeded, a thermal runaway phenomenon may occur, which may cause safety problems.

[0004] That is, if the thermal runaway phenomenon occurring in some battery cells is propagated to adjacent battery cells in a short time, the temperature of the entire battery module will rapidly rise, which may lead to an increase in the temperature of the entire battery pack including a large number of battery modules, and may cause great damage to property and human life. Therefore, in order to prevent such rapid propagation of the thermal runaway phenomenon, it is necessary to apply a member for heat insulation between adjacent battery cells.

[0005] Furthermore, a cushioning material is applied between adjacent battery cells that can be compressed in response to the expansion of the battery cells due to swelling, thereby absorbing the swelling. Such a cushioning material may be an expanded polypropylene pad (EPP pad) or a urethane pad.

[0006] On the other hand, Patent Document 1 discloses a battery module that includes a pair of swelling absorption pads that are compressed in response to volume expansion due to swelling of battery cells, and a thermal insulation pad interposed between the pair of swelling absorption pads to block heat transfer between adjacent battery cells and expand above a predetermined reference temperature. In other words, Patent Document 1 is configured such that, even if the temperature inside the battery module rises above a threshold due to an abnormal heat generation phenomenon occurring in some battery cells, the distance between adjacent battery cells can be kept constant and the propagation of thermal runaway phenomena between adjacent battery cells can be delayed, via the pair of swelling absorption pads and the thermal insulation pad interposed between them.

[0007] Furthermore, Patent Document 2 discloses a battery module that includes at least one buffer pad interposed between battery cells and a heat transfer layer disposed on at least one of the two surfaces of the buffer pad and in surface contact with the battery cells, wherein the heat transfer layer is made of graphite. In other words, this disclosed patent is configured so that the heat generated from the battery cells is transferred to a cooling device via the heat transfer layer containing graphite and then released to the outside.

[0008] Furthermore, Patent Document 3 discloses a battery module that includes a heat-insulating film inside the battery module, but the heat-insulating film includes a sheet-like heat-resistant layer made of mica. In other words, Patent Document 3 is configured to prevent the propagation of heat or flame from a cell where ignition or heat generation has occurred to an adjacent cell via a sheet-like heat-resistant layer made of mica.

[0009] The aforementioned Patent Documents 1 to 3 describe a configuration that either delays the propagation of thermal runaway between adjacent battery cells via a heat-insulating pad or a sheet-like heat-resistant layer made of mica, or transmits heat generated from the battery cells to a cooling device via a heat transfer layer containing graphite and releases it to the outside. In other words, conventional published patents are not configured to simultaneously have a heat dissipation function that releases heat generated from the battery cells and an insulating function that blocks heat from diffusing to other adjacent cells during thermal runaway. For example, mica sheets are used to block heat during thermal runaway, but they cannot achieve the heat dissipation function of the battery cells, and although they can perform a flame propagation prevention function during thermal runaway, they have limitations in that they cannot block heat transfer due to the limits of their insulating performance. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Korean Published Patent Publication No. 2020-0106378 [Patent Document 2] Korean Published Patent No. 2022-0114801 [Patent Document 3] Korean Published Patent No. 2022-0029941 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Therefore, the present invention was developed to solve the problems of the prior art described above, and its objective is to provide a battery module and a battery pack equipped therewith that simultaneously have a heat dissipation function for dissipating heat generated from battery cells and a heat insulation function for blocking heat from spreading to other adjacent battery cells in the event of thermal runaway. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides a battery module comprising a cell stack and a module case housing the cell stack, wherein the cell stack comprises a number of battery cells and at least one heat dissipation and heat insulation composite interposed between the battery cells, the heat dissipation and heat insulation composite comprising a vacuum insulation plate having a vacuum space inside, an insulating coated graphite sheet laminated on one surface of the vacuum insulation plate, and a buffer member made of a flame-retardant material laminated on the other surface of the vacuum insulation plate, wherein the vacuum insulation plate is constructed by press-forming two plates of a metal material and sealing them to have a vacuum space inside, the internal vacuum space is constructed by pressing the surface of one plate into an embossed shape and sealing it so that the embossed surface is in close contact with the inner surface of the other plate, and the vacuum insulation plate is further constructed by arranging a heat conduction suppression sheet between the embossed surfaces that are in contact with each other and the inner surface of the other plate.

[0013] The graphite sheet has a structure in which expanded graphite contains a thermally conductive filler, and preferably has a thermal conductivity of 150 to 350 W / mK in the horizontal direction (plane direction) and a thermal conductivity of 5 to 10 W / mK in the vertical direction.

[0014] The insulating coated graphite sheet is more preferably constructed by coating the entire surface of a graphite substrate with a mixture having electrical insulation and flame retardancy to a thickness of less than 100 μm.

[0015] The heat conduction suppressing sheet is preferably a ceramic fiber, glass fiber, fumed silica, or aerogel-impregnated sheet. The battery module may further include heat sinks arranged in a manner that contacts the battery cells and one end of the heat dissipation and heat insulation complex, and in a manner that contacts each other via gap fillers.

[0016] Also, the battery pack of the present invention for achieving the above object includes a plurality of battery modules and a case for housing the plurality of battery modules. The battery module includes a cell laminate and a module case for housing the cell laminate. The cell laminate includes a plurality of battery cells and at least one heat dissipation and heat insulation composite interposed between the battery cells. The heat dissipation and heat insulation composite is configured as described above.

Advantages of the Invention

[0017] The present invention has the advantage that it can simultaneously exhibit a heat dissipation function of dissipating heat generated from battery cells through a heat dissipation composite, a heat insulation composite, or a heat dissipation and heat insulation composite that exhibits an individual function or simultaneously exhibits two functions between adjacent battery cells, and a heat insulation function of blocking heat so that it does not diffuse to other adjacent battery cells during thermal runaway.

Brief Description of the Drawings

[0018] [Figure 1] It is a perspective view of a battery module according to an embodiment of the present invention. [Figure 2] It is a perspective view of an example of a battery cell applied to the battery module shown in FIG. 1. [Figure 3] It is a conceptual diagram of a state in which a heat dissipation composite or a heat insulation composite is inserted and arranged between battery cells. [Figure 4] It is an exemplary diagram of a cross-sectional structure of the heat dissipation composite shown in FIG. 3. [Figure 5] It is an exemplary diagram of a cross-sectional structure of the heat insulation composite shown in FIG. 3. [Figure 6] It is a cross-sectional view of the shape and structure of the vacuum insulation panel shown in FIG. 5. [Figure 7] It is a perspective view of another shape and structure of the vacuum insulation panel shown in FIG. 5. [Figure 8] It is a cross-sectional view of another shape and structure of the vacuum insulation panel shown in FIG. 5. [Figure 9] It is an exemplary view of a cross-sectional structure of a heat dissipation and heat insulation composite that constitutes a battery module according to another embodiment of the present invention.

Embodiments for Carrying out the Invention

[0019] Hereinafter, preferred embodiments of a battery module with heat dissipation and heat insulation functions and a battery pack including the same according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments disclosed below and can be realized in various different forms. However, this embodiment is provided to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge of the scope of the invention.

[0020] FIG. 1 is a perspective view of a battery module according to an embodiment of the present invention, FIG. 2 is a perspective view of an example of a battery cell applied to the battery module shown in FIG. 1, FIG. 3 is a conceptual view of a state in which a heat dissipation composite or a heat insulation composite is inserted and arranged between battery cells, FIG. 4 is an exemplary view of a cross-sectional structure of the heat dissipation composite shown in FIG. 3, FIG. 5 is an exemplary view of a cross-sectional structure of the heat insulation composite shown in FIG. 3, FIG. 6 is a cross-sectional view of the shape and structure of the vacuum heat insulation plate shown in FIG. 5, and FIGS. 7 and 8 are perspective views and cross-sectional views of other shapes and structures of the vacuum heat insulation plate shown in FIG. 5.

[0021] As shown in FIGS. 1 to 3, the battery module of this embodiment includes a cell stack 100 and a module case 200 that houses the cell stack 100. The cell stack 100 includes a number of battery cells 110 and at least one heat dissipation composite 120 and heat insulation composite 130 interposed between adjacent battery cells 110.

[0022] For example, as the battery cell 110, a pouch-type battery cell can be applied. When the battery cell 110 is a pouch-type battery cell, as shown in FIG. 2, the battery cell 110 can be realized in a form including an electrode assembly (not shown), a cell case 111, an electrode lead 112, and a sealing tape 113.

[0023] The cell case 111 includes a housing portion 111a for housing the electrode assembly, and a sealing portion 111b that extends circumferentially from the housing portion 111a and is sealed by heat fusion with the electrode leads 112 pulled out to the outside, thereby sealing the cell case 111.

[0024] The electrode leads 112 are arranged in pairs and are connected to a positive electrode tab (not shown) and a negative electrode tab (not shown), respectively, and are drawn out to the outside of the cell case 111. The pair of electrode leads 112 are drawn out side by side on one longitudinal side of the battery cell 110, or they are drawn out on one longitudinal side and the other longitudinal side of the battery cell 110, respectively. The battery cell 110 used in this embodiment may be a unidirectional lead type battery cell in which the positive electrode lead and the negative electrode lead are drawn out in the same direction, or it may be a bidirectional lead type battery cell in which they are drawn out in opposite directions.

[0025] The sealing tape 113 is attached around the electrode lead 112 and interposed between the inner surface of the seal portion 111b of the cell case 111 and the electrode lead 112. The sealing tape 113 prevents the sealing performance of the seal portion 111b from decreasing due to the extension of the electrode lead 112.

[0026] The battery cells applicable to this embodiment include the pouch-type battery cells and the prismatic-type battery cells, as well as all battery cells with a structure that can make surface contact with the heat dissipation composite 120 and the heat insulating composite 130, which will be described later.

[0027] As shown in Figure 4, it is preferable that the heat dissipation composite 120 is interposed between adjacent battery cells 110 and has the function of dissipating heat generated from the battery cells and the function of preventing flame propagation in the event of a fire. Therefore, the heat dissipation composite 120 of this embodiment must have excellent heat transfer performance, be lightweight, and be non-flammable. It is also preferable that it includes a buffering member capable of buffering the deformation of components when the battery cells swell. For this purpose, the heat dissipation composite 120 of this embodiment can be constructed by laminating an insulating coated graphite sheet 121 with a thickness of 0.3 to 1.0 mm as a heat transfer member for heat dissipation and a buffering member 122 made of a flame-retardant material such as polyurethane foam. In this case, it is preferable that the buffering member 122 is laminated only on one surface of the insulating coated graphite sheet 121 so that it can perform its basic heat dissipation function.

[0028] The aforementioned graphite sheet may have a structure in which expanded graphite contains a thermally conductive filler, but it is preferable that the thermal conductivity in the horizontal direction (plane direction) is 150 to 350 W / mK and the thermal conductivity in the vertical direction is 5 to 10 W / mK. On the other hand, if the thermal conductivity in the horizontal direction (plane direction) of the graphite sheet is less than 150 W / mK, there is a problem (disadvantage) that the mechanical strength decreases due to low density, and if the thermal conductivity in the horizontal direction (plane direction) of the graphite sheet exceeds 350 W / mK, there is a problem (disadvantage) that the weight increases and production costs rise due to high density, and if the thermal conductivity in the vertical direction is less than 5 W / mK, there is a problem (disadvantage) that the cell heat dissipation performance decreases, and if the thermal conductivity in the vertical direction exceeds 15 W / mK, additional additives are required, which is a problem (disadvantage) that production costs rise. Therefore, it is preferable that the graphite sheet of this embodiment has the above-mentioned thermal conductivity in the horizontal direction (plane direction) and vertical direction.

[0029] On the other hand, a graphite sheet, if made solely from a graphite substrate, does not possess electrical insulation properties. Therefore, it is preferable that the insulating coated graphite sheet 121 of this embodiment be constructed by coating the entire surface of the graphite substrate with a mixed material having electrical insulation and flame retardancy to a thickness of less than 100 μm. However, if the mixed material is coated to a thickness of 100 μm or more, there is a problem (disadvantage) that the effective thermal conductivity of the entire heat dissipation sheet layer, including the coating layer, decreases, so it is preferable to coat the mixed material to a thickness of less than 100 μm. As the mixed material, a ceramic-based or urethane-based material can be used, and an acrylic adhesive component can be mixed in so that battery cells and cushioning members can be attached to it.

[0030] As shown in Figures 5 to 8, it is preferable that the thermal insulation composite 130 is configured to perform two functions: a thermal insulation function that interposes between adjacent battery cells 110 to block heat from diffusing from one battery cell to another adjacent battery cell during thermal runaway, and a function that prevents flame propagation. Therefore, the thermal insulation composite 130 of this embodiment can be constructed by laminating a vacuum insulation plate 131 made of stainless steel, which has excellent thermal insulation performance to prevent heat from diffusing to other adjacent battery cells during thermal runaway, and is also lightweight and non-flammable, with a buffer member 132 made of a flame-retardant material such as polyurethane foam. In this case, it is preferable that the buffer member 132 is laminated only on one surface of the vacuum insulation plate 131 so that the basic thermal insulation function can be performed.

[0031] The vacuum insulation plate 131 is constructed by press-forming two plates 131a and 131b and sealing them to create a vacuum space inside. A metal material such as stainless steel with a thickness of about 0.1 to 0.3 mm can be used to create the vacuum space inside and seal it to achieve excellent insulation performance (thermal conductivity 0.005 W / mK), with a thermal conductivity of about 1 / 60 that of a mica sheet. Furthermore, since the vacuum insulation plate 131 has a vacuum inside, it must prevent collapse under vacuum and withstand the compressive force from the external atmospheric pressure. For this purpose, a porous material 133 with low thermal conductivity can be filled between the two plates 131a and 131b and sealed (see Figure 6), or the surface of at least one plate 131a can be press-formed into an embossed shape, and the embossed surface can be sealed in close contact with the inner surface of the other plate 131b (see Figures 7 and 8). On the other hand, the two plates 131a and 131b are integrated by welding them together along their edges, and welding methods such as argon welding, laser welding, or plasma welding can be used.

[0032] Furthermore, the vacuum insulation plate 131 can also be constructed by further placing a heat conduction suppression sheet 134 between the embossed surfaces that come into contact with each other and the inner surface of the other plate, in order to suppress the heat conduction phenomenon caused by the contact between the two plates 131a and 131b by the embossed surfaces. In this case, the heat conduction suppression sheet can be made of ceramic fiber, glass fiber, fumed silica, or aerogel impregnated sheet, but among these, it is preferable to use a ceramic fiber sheet considering fire resistance of 1,000°C or higher.

[0033] In another embodiment of the present invention, the battery module may be configured to include at least one heat dissipation and heat insulation complex 140 having both functions simultaneously, instead of a heat dissipation complex 120 and a heat insulation complex 130 each having their own individual functions. Here, the heat dissipation and heat insulation complex 140 is interposed between adjacent battery cells.

[0034] Figure 9 is an illustrative diagram of the cross-sectional structure of a heat dissipation and heat insulation composite constituting a battery module according to another embodiment of the present invention. As shown in Figure 9, the heat dissipation and heat insulation composite 140 of this embodiment comprises a vacuum insulation plate 141 having a vacuum space inside, an insulating coated graphite sheet 142 laminated on one surface of the vacuum insulation plate 141, and a flame-retardant buffer member 143 laminated on the other surface of the vacuum insulation plate 141. The vacuum insulation plate 141, the insulating coated graphite sheet 142, and the buffer member 143 of this embodiment can be configured in the same way as the corresponding components described above, so their explanation will be omitted.

[0035] On the other hand, in constructing the heat dissipation and heat insulation composite 140 of this embodiment, it is also possible to construct it by laminating a vacuum insulation plate 141 and a buffer member 143 on both sides with an insulating coated graphite sheet 142 as the base. However, the reason for constructing it by laminating an insulating coated graphite sheet and a buffer member 143 on both sides with a vacuum insulation plate 141 as the base is that the contact surface with the battery cell performs a heat dissipation function, and the intermediate vacuum insulation layer performs a heat insulation function when thermal runaway occurs.

[0036] On the other hand, the battery module of this embodiment may further include a heat sink. Here, the heat sink is made of a metal material such as aluminum or copper and may have a structure in which cooling water flows inside, but is not limited to this. The heat sink is arranged in a manner that contacts one end of the battery cell 110, heat dissipation complex 120, heat insulation complex 130 in Figure 3, and heat dissipation and heat insulation complex 140 in Figure 9, but has a configuration in which it contacts each other via a gap filler. Therefore, heat generated from the battery cell 110 is more effectively transferred to the heat sink via the gap filler, enabling efficient heat dissipation.

[0037] The battery pack of this embodiment may consist of a number of battery modules having the configuration relationships described above, and a case that houses the number of battery modules. The case of this embodiment may consist of a case with a general configuration relationship applicable to battery packs, so a specific explanation of it will be omitted.

[0038] The technical details relating to the heat dissipation and heat insulation battery module and battery pack equipped therewith of the present invention have been described above with reference to the accompanying drawings. This is an illustrative description of preferred embodiments of the present invention. Therefore, it is obvious to those with ordinary skill in the art that the present invention is not limited to the above embodiments and can be modified and transformed in various ways without departing from the spirit and scope of the present invention. Thus, such modifications or alterations should also be considered to fall within the scope of the claims of the present invention. [Industrial applicability]

[0039] The present invention, when applied to battery modules and / or battery packs such as those in electric vehicles and ESSs, can simultaneously provide a heat dissipation function that dissipates heat generated from battery cells and a heat insulation function that blocks heat from spreading to other adjacent battery cells in the event of thermal runaway.

Claims

1. A battery module comprising a cell stack and a module case housing the cell stack, The cell stack comprises a number of battery cells and at least one heat dissipation and heat insulating composite interposed between the battery cells. The heat dissipation and heat insulation composite comprises a vacuum insulation plate having a vacuum space inside, an insulating coated graphite sheet laminated on one surface of the vacuum insulation plate, and a flame-retardant buffer member laminated on the other surface of the vacuum insulation plate. The vacuum insulation plate is constructed by press-forming two plates of metal material and sealing them to create a vacuum space inside. The internal vacuum space is formed by pressing the surface of one plate into an embossed shape, and sealing it so that the embossed surface is in close contact with the inner surface of the other plate. A battery module with heat dissipation and heat insulation functions, characterized in that the vacuum insulation plate is configured by further arranging a heat conduction suppression sheet between the embossed surfaces that come into contact with each other and the inner surfaces of other plates.

2. The battery module with heat dissipation and heat insulation function according to claim 1, characterized in that the graphite sheet has a structure in which expanded graphite contains a thermally conductive filler, and the thermal conductivity in the horizontal direction (plane direction) is 150 to 350 W / mK, and the thermal conductivity in the vertical direction is 5 to 10 W / mK.

3. The battery module with heat dissipation and heat insulation function according to claim 2, characterized in that the insulating coated graphite sheet is constructed by coating the entire surface of a graphite substrate with a mixed material having electrical insulation and flame retardancy to a thickness of less than 100 μm.

4. The heat dissipation and heat insulation battery module according to claim 1, characterized in that the heat conduction suppression sheet is a ceramic fiber, glass fiber, fumed silica, or aerogel impregnated sheet.

5. The battery module with heat dissipation and heat insulation function according to claim 1, further comprising a heat sink arranged in a manner that contacts one end of the battery cell and the heat dissipation and heat insulation complex, but in a manner that contacts each other via a gap filler.

6. A battery pack comprising a number of battery modules and a case for housing the number of battery modules, The battery module includes a cell stack and a module case that houses the cell stack. The cell stack comprises a number of battery cells and at least one heat dissipation and heat insulating composite interposed between the battery cells. The heat dissipation and heat insulation composite comprises a vacuum insulation plate having a vacuum space inside, an insulating coated graphite sheet laminated on one surface of the vacuum insulation plate, and a flame-retardant buffer member laminated on the other surface of the vacuum insulation plate. The vacuum insulation plate is constructed by press-forming two plates of metal material and sealing them to create a vacuum space inside. The internal vacuum space is created by pressing the surface of one plate into an embossed shape, and sealing it so that the embossed surface is in close contact with the inner surface of the other plate. The battery pack is characterized in that the vacuum insulation plate is further configured by placing a heat conduction suppression sheet between the embossed surface that is in contact with the other plate and the inner surface of the other plate.

7. The battery pack according to claim 6, characterized in that the graphite sheet has a structure in which expanded graphite contains a thermally conductive filler, and has a thermal conductivity of 150 to 350 W / mK in the horizontal direction (plane direction) and a thermal conductivity of 5 to 10 W / mK in the vertical direction.

8. The battery pack according to claim 7, characterized in that the insulating coated graphite sheet is constructed by coating the entire surface of a graphite substrate with a mixture having electrical insulation and flame retardancy to a thickness of less than 100 μm.

9. The battery pack according to claim 6, characterized in that the heat conduction suppressing sheet is a ceramic fiber, glass fiber, fumed silica, or aerogel-impregnated sheet.

10. The battery pack according to claim 6, further comprising a heat sink arranged in a manner that contacts one end of the battery cell and the heat dissipation and heat insulation composite, but in a manner that contacts each other via a gap filler.

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