Battery module with heat dissipation and heat insulation functions and battery pack including the same

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 from diffusing to adjacent battery cells in the event of thermal runaway. The present invention also relates to a battery pack including the battery module. [Background technology]

[0002] Generally, a battery module is equipped with a cooling system to prevent the lifespan of the battery module from being rapidly shortened due to temperature changes caused by long-term use, and such a cooling system is designed taking into consideration the amount of heat generated according to the usage environment of the battery module.

[0003] However, if a battery module shows abnormal heat due to a failure in some battery cells during use, the temperature may continue to rise. In this case, if the critical temperature is exceeded, thermal runaway may occur, causing safety issues.

[0004] That is, if a thermal runaway phenomenon that occurs in some battery cells spreads to adjacent battery cells in a short period of time, the temperature of the entire battery module will rise rapidly, which may lead to a rise in the temperature of the entire battery pack including multiple battery modules, which may cause significant damage to property and human life. Therefore, in order to prevent such a rapid spread of the thermal runaway phenomenon, it is necessary to apply a heat-shielding member between adjacent battery cells.

[0005] In addition, a buffer member capable of absorbing swelling by being compressed in response to expansion of the battery cells due to swelling is applied between adjacent battery cells. As such a buffer member, an expanded polypropylene (EPP) pad, a urethane pad, or the like may be used.

[0006] Meanwhile, Patent Document 1 discloses a battery module including a pair of swelling absorption pads that are compressed in response to volumetric expansion due to swelling of battery cells, and a heat insulating pad that is interposed between the pair of swelling absorption pads to block heat transfer between adjacent battery cells and expands at or above a predetermined reference temperature. That is, Patent Document 1 is configured to maintain a constant gap between adjacent battery cells and delay the propagation of thermal runaway between the adjacent battery cells through the pair of swelling absorption pads and the heat insulating pad interposed therebetween, even if the temperature within the battery module rises above a threshold due to abnormal heat generation in some battery cells.

[0007] Patent Document 2 also 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 surfaces of the buffer pad and in surface contact with the battery cells, the heat transfer layer including graphite. That is, this published patent discloses a configuration in which heat generated from the battery cells is transferred to a cooling device via the heat transfer layer including graphite and then released to the outside.

[0008] Furthermore, Patent Document 3 discloses a battery module that includes a heat-shielding film inside the battery module, and the heat-shielding film includes a sheet-like heat-resistant layer made of mica. That is, Patent Document 3 is configured to prevent the propagation of heat or flame from a cell in which ignition or heat generation has occurred to adjacent cells via the sheet-like heat-resistant layer made of mica.

[0009] The above-mentioned Patent Documents 1 to 3 are configured to delay the propagation of thermal runaway between adjacent battery cells through a heat-insulating pad or a sheet-like heat-resistant layer made of mica, or to transfer heat generated from the battery cells to a cooling device via a heat-transfer layer containing graphite and release it to the outside. In other words, the prior published patents are not configured to simultaneously have a heat dissipation function for dissipating heat generated from the battery cells and a heat-insulating function for blocking heat so that it does not diffuse 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. Even during thermal runaway, while they can prevent flame propagation, they are limited in that they cannot block heat transfer due to their limited insulation performance. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 2020-0106378 [Patent Document 2] Korean Patent Publication No. 2022-0114801 [Patent Document 3] Korean Patent Publication No. 2022-0029941 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the present invention has been developed to solve the above-mentioned problems of the conventional technology, and its purpose is to provide a battery module and a battery pack including the same that simultaneously have a heat dissipation function for dissipating heat generated from a battery cell and a heat insulation function for blocking heat so that it does not spread to other adjacent battery cells in the event of thermal runaway. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides a battery module comprising: 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 insulation composite interposed between the battery cells. The heat dissipation and insulation composite comprises a vacuum insulated plate having an internal vacuum space; an insulating coated graphite sheet laminated on one surface of the vacuum insulated plate; and a buffer member made of a flame-retardant material laminated on the other surface of the vacuum insulated plate. The vacuum insulated plate is formed by press-forming two metal plates and sealing them to form an internal vacuum space. The internal vacuum space is formed by pressing the surface of one plate into an embossed shape and sealing the embossed surface in close contact with the inner surface of the other plate. The vacuum insulated plate further comprises a heat conduction-suppressing sheet disposed between the embossed surfaces that come into contact with each other and the inner surface of the other plate.

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

[0014] More preferably, the insulating coated graphite sheet is constructed by coating an electrically insulating and flame-retardant mixed material on the entire surface of a graphite substrate 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 a heat sink disposed in contact with the battery cells and one end of the heat dissipation and heat insulation composite, the heat sink and the battery cells being in contact with each other via a gap filler.

[0016] In addition, to achieve the above-mentioned object, the battery pack of the present invention includes a plurality of battery modules and a case that houses the plurality of battery modules, wherein the battery module includes a cell stack and a module case that houses the cell stack, and the cell stack includes a plurality of battery cells and at least one heat dissipation and heat insulation composite interposed between the battery cells, and the heat dissipation and heat insulation composite is configured as described above. [Effects of the Invention]

[0017] The present invention has the advantage that it can simultaneously perform a heat dissipation function of dissipating heat generated from a battery cell and a heat insulation function of blocking heat so that it does not diffuse to other adjacent battery cells in the event of thermal runaway, through a heat dissipation composite, a heat insulation composite, or a heat dissipation and heat insulation composite that is interposed between adjacent battery cells and performs individual functions or performs two functions simultaneously. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a battery module according to an embodiment of the present invention; [Figure 2] 2 is a perspective view of an example battery cell applied to the battery module shown in FIG. 1. [Figure 3] FIG. 10 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] 4 is an exemplary view showing a cross-sectional structure of the heat dissipation composite shown in FIG. 3. [Figure 5] 4 is an exemplary diagram of a cross-sectional structure of the thermal insulation composite shown in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view of the shape and structure of the vacuum insulation plate shown in FIG. 5. [Figure 7] 6 is a perspective view of another shape and structure of the vacuum insulation plate shown in FIG. 5. FIG. [Figure 8] 6 is a cross-sectional view of another shape and structure of the vacuum insulation plate shown in FIG. 5. FIG. [Figure 9] 10 is an exemplary cross-sectional view of a heat dissipation and insulation composite constituting a battery module according to another embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, preferred embodiments of a battery module with heat dissipation and 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 following disclosed embodiments, and may be embodied in various different forms. However, the present embodiments are provided to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0020] FIG. 1 is a perspective view of a battery module according to one embodiment of the present invention, FIG. 2 is a perspective view of an example battery cell applied to the battery module shown in FIG. 1, FIG. 3 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, FIG. 4 is an example diagram of the cross-sectional structure of the heat dissipation composite shown in FIG. 3, FIG. 5 is an example diagram of the 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 insulation plate shown in FIG. 5, and FIGS. 7 and 8 are perspective and cross-sectional views of other shapes and structures of the vacuum insulation plate shown in FIG. 5.

[0021] 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, a pouch-type battery cell may be used as the battery cell 110. When the battery cell 110 is a pouch-type battery cell, the battery cell 110 may be realized in a form including an electrode assembly (not shown), a cell case 111, electrode leads 112, and a sealing tape 113, as shown in FIG.

[0023] The cell case 111 includes a receiving portion 111a that receives the electrode assembly, and a sealing portion 111b that extends circumferentially around the receiving portion 111a and seals the cell case 111 by being heat-sealed with the electrode lead 112 pulled out to the outside.

[0024] The electrode leads 112 are configured in pairs, connected to a positive electrode tab (not shown) and a negative electrode tab (not shown), respectively, and drawn out to the outside of the cell case 111. The pair of electrode leads 112 are drawn out side by side in the longitudinal direction of the battery cell 110, or drawn out to one side and the other side in the longitudinal direction of the battery cell 110, respectively. The battery cell 110 applied to the present embodiment may be a one-way drawn battery cell in which the positive electrode lead and the negative electrode lead are drawn out in the same direction, or may be a two-way drawn battery cell in which the positive electrode lead and the negative electrode lead are drawn out in opposite directions.

[0025] The sealing tape 113 is attached around the electrode lead 112 and is 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 ability of the seal portion 111b from being reduced due to the electrode lead 112 being pulled out.

[0026] The battery cells applicable to this embodiment include all battery cells having a structure that can be in surface contact with the heat dissipation composite 120 and the heat insulation composite 130 described below, as well as the pouch-type battery cells and the square-type battery cells.

[0027] As shown in FIG. 4, the heat dissipation composite 120 is preferably configured to be interposed between adjacent battery cells 110 and to have the functions of dissipating heat generated from the battery cells and 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 also preferably includes a buffer member that can buffer deformation of components during swelling of the battery cells. To this end, the heat dissipation composite 120 of this embodiment may be configured by laminating an insulating-coated graphite sheet 121 having a thickness of 0.3 to 1.0 mm as a heat transfer member for heat dissipation and a buffer member 122 made of a flame-retardant material such as polyurethane foam. In this case, it is preferable that the buffer member 122 be laminated on only one surface of the insulating-coated graphite sheet 121 to ensure the basic heat dissipation function.

[0028] The graphite sheet may have a structure in which thermally conductive filler is mixed with expanded graphite. 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, the density is low, resulting in reduced mechanical strength. If the thermal conductivity in the horizontal direction (plane direction) of the graphite sheet is more than 350 W / mK, the density is high, resulting in increased weight and higher production costs. If the thermal conductivity in the vertical direction is less than 5 W / mK, the cell heat dissipation performance is reduced. If the thermal conductivity in the vertical direction is more than 15 W / mK, an additional additive is required, resulting in increased production costs. Therefore, the graphite sheet of this embodiment preferably has the thermal conductivities in the horizontal direction (plane direction) and vertical direction within the above range.

[0029] On the other hand, a graphite sheet does not have electrical insulation properties when made solely from a graphite substrate. Therefore, the insulating-coated graphite sheet 121 of this embodiment is preferably constructed by coating an electrically insulating and flame-retardant composite material on the entire surface of the graphite substrate to a thickness of less than 100 μm. However, coating the composite material to a thickness of more than 100 μm can have the drawback of reducing the effective thermal conductivity of the entire heat-dissipating sheet layer, including the coating layer. Therefore, it is preferable to coat the composite material to a thickness of less than 100 μm. The composite material may be a ceramic-based or urethane-based material, and may contain an acrylic adhesive component to allow attachment of the battery cell and buffer member.

[0030] 5 to 8, the heat insulating composite 130 is preferably configured to be interposed between adjacent battery cells 110 and to perform the functions of insulating heat from the battery cell to prevent heat from diffusing to adjacent battery cells in the event of thermal runaway, and of preventing flame propagation. Therefore, the heat insulating composite 130 of this embodiment can be configured by laminating a vacuum insulation plate 131 made of a stainless steel material that has excellent heat insulating performance to prevent heat from diffusing to adjacent battery cells in the event of thermal runaway, as well as being lightweight and non-flammable, and a buffer member 132 made of a flame-retardant material such as polyurethane foam. In this case, the buffer member 132 is preferably laminated on only one surface of the vacuum insulation plate 131 so that the basic thermal insulation function can be maintained.

[0031] The vacuum insulation plate 131 is formed by press-forming two plates 131a and 131b and sealing them to form a vacuum space inside. The vacuum space can be formed using a metal material such as stainless steel with a thickness of about 0.1 to 0.3 mm and sealed, resulting in excellent thermal insulation performance (thermal conductivity 0.005 W / mK) with a thermal conductivity of about 1 / 60 that of a mica sheet. Furthermore, the vacuum insulation plate 131 has a vacuum inside, so it must prevent collapse during vacuum formation and withstand compressive force due to external atmospheric pressure. To this end, a porous material 133 with low thermal conductivity may be filled between the two plates 131a and 131b and sealed (see FIG. 6). Alternatively, the surface of at least one plate 131a may be pressed into an embossed shape, with the embossed surface in close contact with the inner surface of the other plate 131b and sealed (see FIGS. 7 and 8). Meanwhile, the two plates 131a and 131b are integrated together by welding them together along their edges, and the welding method can be argon welding, laser welding, plasma welding, or the like.

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

[0033] A battery module according to another embodiment of the present invention may include at least one heat dissipation and heat insulation composite 140 having two functions at the same time, instead of the heat dissipation composite 120 and the heat insulation composite 130 each having separate functions. Here, the heat dissipation and heat insulation composite 140 is interposed between adjacent battery cells.

[0034] 9 is an exemplary cross-sectional view of a heat dissipation and heat insulation composite constituting a battery module according to another embodiment of the present invention. As shown in FIG. 9, the heat dissipation and heat insulation composite 140 of this embodiment includes a vacuum insulation plate 141 having a vacuum space therein, an insulatingly coated graphite sheet 142 laminated on one surface of the vacuum insulation plate 141, and a buffer member 143 made of a flame-retardant material laminated on the other surface of the vacuum insulation plate 141. The vacuum insulation plate 141, the insulatingly coated graphite sheet 142, and the buffer member 143 of this embodiment may be configured in the same manner as the corresponding components described above, and therefore, description thereof will be omitted.

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

[0036] Meanwhile, the battery module of this embodiment may further include a heat sink. Here, the heat sink may be made of a metal material such as aluminum or copper and have a structure in which coolant flows inside, but is not limited thereto. The heat sink is disposed in contact with one end of the battery cell 110, the heat dissipation composite 120, and the heat insulation composite 130 of FIG. 3, and the heat dissipation and heat insulation composite 140 of FIG. 9, and is in contact with each other via a gap filler. Therefore, heat generated from the battery cell 110 is more efficiently transferred to the heat sink via the gap filler, allowing for efficient heat dissipation.

[0037] The battery pack of this embodiment may include a number of battery modules having the above-described structural relationship and a case for accommodating the number of battery modules. The case of this embodiment may be configured as a case having a general structural relationship that is applied to battery packs, and therefore a detailed description thereof will be omitted.

[0038] The present invention has been described above with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention. Therefore, the present invention is not limited to the above embodiments. It is obvious to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications and variations are also within the scope of the present invention. [Industrial Applicability]

[0039] When applied to a battery module and / or battery pack of an electric vehicle, ESS, or the like, the present invention can simultaneously perform a heat dissipation function to dissipate heat generated from a battery cell and a heat insulation function to block heat from diffusing to other adjacent battery cells in the event of thermal runaway.

Claims

1. A battery module including a cell stack and a module case that houses the cell stack, The cell stack includes 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 includes a vacuum insulation plate having a vacuum space therein, 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, The vacuum insulation plate is formed by press-forming two plates made of a metal material and sealing them to have a vacuum space inside. The internal vacuum space is formed by pressing the surface of one plate into an embossed shape and sealing the embossed surface in close contact with the inner surface of the other plate. The vacuum insulation plate is configured by further disposing a heat conduction suppression sheet between the embossed surface and the inner surface of another plate that are in contact with each other.

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

3. 3. The battery module with heat dissipation and insulation functions according to claim 2, wherein the insulating-coated graphite sheet is formed by coating an electrically insulating and flame-retardant composite material on an entire surface of a graphite substrate to a thickness of less than 100 μm.

4. The battery module with heat dissipation and insulation functions according to claim 1 , wherein the heat conduction-suppressing sheet is a ceramic fiber, glass fiber, fumed silica, or aerogel-impregnated sheet.

5. 2. The battery module with heat dissipation and insulation functions according to claim 1, further comprising a heat sink arranged to be in contact with the battery cell and one end of the heat dissipation and insulation composite via a gap filler.

6. A battery pack including a number of battery modules and a case that houses the number of battery modules, the battery module includes a cell stack and a module case that houses the cell stack; The cell stack includes 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 includes a vacuum insulation plate having a vacuum space therein, 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, The vacuum insulation plate is formed by press-forming two plates made of a metal material and sealing them to have a vacuum space inside. The internal vacuum space is formed by pressing the surface of one plate into an embossed shape and sealing the embossed surface in close contact with the inner surface of the other plate. The battery pack is characterized in that the vacuum insulation plate is configured by further disposing a heat conduction suppressing sheet between the embossed surface and the inner surface of another plate that are in contact with each other.

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

8. 10. The battery pack of claim 7, wherein the insulating-coated graphite sheet is formed by coating an electrically insulating and flame-retardant composite material on an entire surface of a graphite substrate to a thickness of less than 100 μm.

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

10. 7. The battery pack of claim 6, further comprising a heat sink arranged to be in contact with the battery cell and one end of the heat dissipation and heat insulation composite via a gap filler.

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