Battery module and battery pack containing it

Abstract

To provide a battery module and a battery pack including the same, the battery module effectively reducing the rate of heat propagation between battery cells.SOLUTION: A battery module according to one embodiment comprises: a battery cell stack formed by stacking a plurality of battery cells; and a barrier layer interposed between mutually adjacent battery cells of the plurality of battery cells, where the thickness of the barrier layer varies depending on positions.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] [Cross - References to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2020 - 0137479, filed on October 22, 2020, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a battery module and a battery pack including the same, and more particularly, to a battery module that effectively delays the heat propagation rate between battery cells and a battery pack including the same.

Background Art

[0003] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source has been rapidly increasing. In particular, secondary batteries are attracting much attention not only as an energy source for mobile devices such as mobile phones, digital cameras, notebook computers, and wearable devices, but also for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0004] For small mobile devices, one or more battery cells are used per device, while for medium - to - large - sized devices such as automobiles, high - power and large - capacity are required. Therefore, medium - to - large - sized battery modules in which a large number of battery cells are electrically connected are used.

[0005] Medium - to - large - sized battery modules are preferably manufactured to be as small and light as possible, so that they can be stacked with a high degree of integration, and prismatic batteries, pouch - type batteries, etc., which have a small weight relative to their capacity, are mainly used as the battery cells of medium - to - large - sized battery modules. On the other hand, the battery module can include a module frame with open front and rear surfaces for accommodating a battery cell stack in an internal space to protect the battery cell stack from external impacts, heat, or vibrations.

[0006] Figure 1 is a perspective view of a conventional battery module. Figure 2 is a top view of a battery cell stack included in a conventional battery module. Figure 3(a) is a top view of area A in Figure 2, and Figure 3(b) is a cross-sectional view taken along the cutting surface BB of (a).

[0007] Referring to Figures 1 and 2, a conventional battery module includes a battery cell stack 12 in which multiple battery cells 11 are stacked in one direction, module frames 30 and 40 that house the battery cell stack 12, and end plates 15 that cover the front and rear surfaces of the battery cell stack 12. The module frames 30 and 40 include a lower frame 30 that covers the bottom and both sides of the battery cell stack 12 and an upper plate 40 that covers the top surface of the battery cell stack 12.

[0008] Furthermore, the battery cell stack 12 includes fixing members 17 that secure multiple battery cells 11 to each other, and the fixing members 17 are located in the center and / or at the ends of the battery cell stack 12. In addition, compression pads 20 are located between pairs of adjacent battery cells in the battery cell stack 12.

[0009] Referring to Figures 2 and 3, the compression pad 20 located in a conventional battery cell stack is in contact with the upper or lower surface of the battery cell 11. The compression pad 20 absorbs the shock that propagates to adjacent battery cells 11. Furthermore, when a battery cell 11 ignites, the thickness of the compression pad 20 can delay the heat propagation rate. However, if a swelling phenomenon occurs during the charging and discharging process of the battery cell 11, pressure and / or heat will be applied to the compression pad 20. At this time, the compression ratio of the conventional compression pad 20 will differ depending on its position, which changes the physical properties of the compression pad 20. In addition to this, when a battery cell 110 ignites, secondary cell ignition can occur due to heat conduction between adjacent battery cells 11 as well as external heat conduction from the flame generated in the battery cell 11.

[0010] As a result, conventional compression pads 20 alone are insufficient to adequately slow down the heat propagation speed. Therefore, unlike conventional designs, it is necessary to develop a battery module that effectively slows down the heat propagation speed between battery cells even when swelling occurs. [Overview of the project] [Problems that the invention aims to solve]

[0011] The problem that this invention aims to solve is to provide a battery module and a battery pack including the same that effectively delay the heat transfer rate between battery cells.

[0012] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0013] A battery module according to one embodiment of the present invention includes a battery cell stack formed by stacking a plurality of battery cells, and a barrier layer interposed between adjacent battery cells among the plurality of battery cells, wherein the thickness of the barrier layer varies depending on its position.

[0014] The thickness of the barrier layer may increase towards the edges, with reference to the surface facing the body of the battery cell.

[0015] The barrier layer may include a first barrier portion that covers the body portion of the battery cell and a second barrier portion that extends from the first barrier portion and covers the top portion of the battery cell.

[0016] The thickness of the first barrier portion may be greater than the thickness of the second barrier portion.

[0017] The second barrier portion may be formed from a flexible material.

[0018] The top portion of the battery cell may include a first region covered by the second barrier portion and a second region not covered by the second barrier portion.

[0019] The barrier layer may further include a third barrier portion covering the end portion of the battery cell around the electrode lead protruding from the battery cell.

[0020] An opening through which the electrode lead penetrates may be formed in the third barrier portion.

[0021] The barrier layer may be formed of a flame retardant member.

[0022] The barrier layer may be formed of a silicone conformable pad or a mica sheet.

[0023] At least two or more barrier layers may be included, and at least two or more battery cells may be located between two adjacent barrier layers among the barrier layers.

[0024] The barrier layer may cover one of the two surfaces of the battery cell and may extend above the barrier layer to cover a part of the other surface of the battery cell.

[0025] The barrier layer may guide the direction of the flame generated in the battery cell by an asymmetric structure.

[0026] A battery pack according to another embodiment of the present invention includes the battery module described above.

Advantages of the Invention

[0027] According to the embodiment, by functioning as a flame retardant member, the barrier layer formed between a pair of adjacent battery cells in the battery cell laminate can delay the heat propagation speed between adjacent battery cells when the battery cell ignites.

[0028] Further, by applying the barrier layer not only to the body portion of the battery cell but also to the top portion and the lead portion of the battery cell extending therefrom, the heat transfer rate to the battery cell where no flame is generated by the flame outside the cell can be delayed.

[0029] Also, by forming the barrier layer so that the thickness varies by position, the compression rate of the barrier layer is reduced during the cell swelling phenomenon, maximizing the performance as a flame retardant member, and thereby effectively delaying the heat transfer time between battery cells.

[0030] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

Brief Description of the Drawings

[0031] [Figure 1] It is a perspective view of a conventional battery module. [Figure 2] It is a top view of a battery cell laminate included in a conventional battery module. [Figure 3] (a) is a top view of the A region of FIG. 2 seen from above, and (b) is a cross-sectional view taken along the cutting plane B - B of (a). [Figure 4] It is a diagram showing a method of forming a battery cell laminate according to a comparative example. [Figure 5] It is a diagram showing a method of forming a battery cell laminate included in a battery module according to an embodiment of the present invention. [Figure 6] It is a perspective view showing one battery cell included in the battery cell laminate of FIG. 5. [Figure 7] It is a front view showing a barrier layer wrapping one battery cell included in the battery cell laminate of FIG. 5. [Figure 8] It is a perspective view showing a battery cell laminate formed by combining the battery cells of FIG. 5. [Figure 9] It is a plan view showing a barrier layer formed on the body portion of a battery cell included in a battery module according to another embodiment of the present invention. [Figure 10] This is a cross-sectional view taken along the cutting line PP in Figure 9. [Figure 11] This is a perspective view showing a barrier layer covering a battery cell according to another embodiment of the present invention. [Figure 12] This is a perspective view of the battery cell shown in Figure 11, rotated 180 degrees and facing the opposite side. [Figure 13] Figure 11 is a perspective view showing a battery cell stack formed using the battery cells and barrier layer. [Figure 14] Figure 11 is a perspective view showing the path through which the flame is discharged when a battery cell ignites, according to the embodiment. [Modes for carrying out the invention]

[0032] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily implement them. The present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.

[0033] To clearly illustrate the present invention, irrelevant parts have been omitted, and the same reference numerals are used throughout the specification for identical or similar components.

[0034] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrary for illustrative purposes, and therefore the present invention is not necessarily limited to those shown. Thicknesses are exaggerated in the drawings to clearly represent multiple layers and regions. And, for illustrative purposes, the thicknesses of some layers and regions are exaggerated in the drawings.

[0035] Furthermore, when a part such as a layer, membrane, region, or plate is said to be "on top of" or "on top of" another part, this includes not only the case where it is "immediately above" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "immediately above" another part, it means that there is no other part in between. Also, being "on top of" or "on top of" a reference part means being located above or below the reference part, and does not necessarily mean being located "up" or "on top of" in the opposite direction of gravity.

[0036] Furthermore, when a specification states that a part "includes" a certain component, unless otherwise indicated, this means that it may include other components rather than excluding them.

[0037] Furthermore, throughout the specification, "on a plane" refers to the view of the subject from above, and "on a cross-section" refers to the view of a cross-section obtained by cutting the subject perpendicularly, viewed from the side.

[0038] Figure 4 shows a method for forming a battery cell stack using a comparative example.

[0039] Referring to Figure 4, when stacking the battery cells 11, a compression pad 20 is interposed between adjacent battery cells 11. After stacking the compression pads 20, the stacking of battery cells 11 can be continued. At this time, the compression pad 20 can have a constant thickness. The compression pad 20 can prevent cell swelling and delay heat propagation to some extent when a cell ignites. The battery cells 11 and compression pads 20 are stacked to form a battery cell stack, and a battery module can be formed by subsequent lead welding and module frame processes.

[0040] Figure 5 shows a method for forming a battery cell stack included in a battery module according to one embodiment of the present invention. Figure 6 is a perspective view showing one battery cell included in the battery cell stack of Figure 5. Figure 7 is a front view showing the barrier layer surrounding one battery cell included in the battery cell stack of Figure 5.

[0041] Referring to Figure 5, the battery cell stack included in the battery module according to this embodiment is formed by stacking a plurality of battery cells 110, and includes a barrier layer 200 interposed between adjacent battery cells 110. The barrier layer 200 is made of a flame-retardant material. In this case, the barrier layer 200 can be made of a silicone foam pad or a mica sheet. The battery module includes at least two barrier layers 200, and although not shown, at least two battery cells 110 can be positioned between two adjacent barrier layers 200.

[0042] The battery cell 110 according to this embodiment is preferably a pouch-type battery cell. For example, referring to Figure 6, the battery cell 110 according to this embodiment has a structure in which two electrode leads 111 and 112 face each other and protrude from one end 114a and the other end 114b of the battery body 113, respectively. The battery cell 110 can be manufactured by housing an electrode assembly (not shown) in the battery case 114 and bonding both ends 114a and 114b of the case 114 and the two side surfaces 114c that connect them. In other words, the battery cell 110 according to this embodiment has a total of three sealing parts 114sa, 114sb, and 114sc, and the sealing parts 114sa, 114sb, and 114sc are sealed by methods such as heat fusion, and the remaining other side part is a connecting part 115. The distance between both ends 114a and 114b of the battery case 114 can be defined as the longitudinal direction of the battery cell 110, and the distance between one side portion 114c connecting both ends 114a and 114b of the battery case 114 and the connecting portion 115 can be defined as the width direction of the battery cell 110.

[0043] The connecting portion 115 is a region that extends along one edge of the battery cell 110, and a protruding portion 110p of the battery cell 110 is formed at the end of the connecting portion 115. The protruding portion 110p is formed at least one of the ends of the connecting portion 115 and may protrude in a direction perpendicular to the direction in which the connecting portion 115 extends. The protruding portion 110p is located between the connecting portion 115 and one of the sealing portions 114sa, 114sb of both ends 114a, 114b of the battery case 114.

[0044] The battery case 114 is generally formed with a laminate structure of resin layer / metal foil film layer / resin layer. For example, if the surface of the battery case is formed with an O(oriented)-nylon layer, when stacking a large number of battery cells to form a medium-to-large battery module, it tends to become slippery due to external impacts. Therefore, in order to prevent this and maintain a stable stacked structure of battery cells, an adhesive member such as double-sided tape or a chemical adhesive that bonds through a chemical reaction during bonding can be attached to the surface of the battery case to form a battery cell stack. In this embodiment, the battery cell stack 120 can be stacked in the y-axis direction.

[0045] Referring to Figures 5 to 7, the barrier layer 200 according to this embodiment may include a first barrier portion 200a covering the body portion 110B of the battery cell 110, and a second barrier portion 200b extending from the first barrier portion 200a and covering the top portion 110T of the battery cell 110. The body portion 110B of the battery cell 110 refers to one surface of the battery cell 110 in the y-axis direction, which is the direction in which the battery cells 110 are stacked, and the top portion 110T of the battery cell 110 may be the portion corresponding to one side portion 114c connecting both ends 114a, 114b of the battery case 114. In other words, the top portion 110T of the battery cell 110 can indicate the upper end with respect to the width direction of the battery cell 110.

[0046] In this case, the thickness of the first barrier portion 200a may be greater than the thickness of the second barrier portion 200b. The second barrier portion 200b can be made of a flexible material. A relatively thick first barrier portion 200a can enhance the flame retardant performance that blocks heat propagation between adjacent battery cells 110, while a relatively thin second barrier portion 200b can minimize the occurrence of a gap between the module frame housing the battery cell stack and the upper end of the battery cell 110. Furthermore, by forming the second barrier portion 200b with a flexible material, it can tightly cover the double-sided folding structure at the upper end of the battery cell 110.

[0047] Referring to Figure 7, the barrier layer 200 according to this embodiment may further include a third barrier portion 200c that covers the end portion of the battery cell 110 around the electrode leads 111 and 112 protruding from the battery cell 110. An opening 200A can be formed in the third barrier portion 200c through which the electrode leads 111 and 112 pass.

[0048] Figure 8 is a perspective view showing a battery cell stack formed by combining the battery cells shown in Figure 5.

[0049] Referring to Figures 5 to 8, the battery module including the battery cell stack according to this embodiment, by including the first barrier portion 200a, can block heat conduction from the ignited battery cell 110 to the adjacent battery cell 110 when a cell ignites. Furthermore, by including a second barrier portion 200b covering the top portion 110T in addition to the body portion 110B of the battery cell 110, and a third barrier portion 200c covering the ends of the battery cell 110 around the electrode leads 111 and 112, the effect of heat conduction by an external flame to battery cells 110 that are not ignited can be offset. For example, referring to Figure 8, when ignition occurs in the first battery cell 110a, heat conduction due to the external flame can be offset in the second battery cell 110b to which the barrier layer 200 is applied.

[0050] Figure 9 is a plan view showing a barrier layer formed on the body portion of a battery cell included in another embodiment of the present invention. Figure 10 is a cross-sectional view taken along the cutting line PP in Figure 9.

[0051] Referring to Figures 9 and 10, the barrier layer 200 in this embodiment may have different thicknesses depending on the location. Specifically, the thickness of the barrier layer 200 increases towards the edge, with the surface facing the body portion 110B of the battery cell 110 as the reference point. Conventionally, the cell swelling phenomenon due to the charging of the battery cell 110 was not considered, and the compression pad 20 described in Figure 4, which has the same thickness in all areas, was applied to the barrier layer. When the compression pad is compressed due to the cell swelling phenomenon, the physical properties of the barrier layer may change. In contrast, according to this embodiment, the thickness of the barrier layer 200 can be applied differently in different areas, taking the cell swelling phenomenon into consideration. Therefore, the compressibility of the barrier layer 200 during the cell swelling phenomenon can be lowered to maximize its performance as a flame retardant, thereby effectively delaying the heat propagation time between the battery cells 110. The explanation of the battery cell 110 described in Figures 5 to 8 can also be applied to this embodiment. For example, the thickness of the first barrier portion 200a described in Figures 5 to 8 can be formed to differ depending on the location.

[0052] Figure 11 is a perspective view showing a barrier layer covering a battery cell according to another embodiment of the present invention. Figure 12 is a perspective view of the battery cell from Figure 11 rotated 180 degrees and facing the opposite side. Figure 13 is a perspective view showing a battery cell stack formed using the battery cell and barrier layer from Figure 11. Figure 14 is a perspective view showing the path through which flames are discharged when a battery cell ignites according to the embodiment of Figure 11.

[0053] Referring to Figures 11 and 12, the barrier layer 200 covers one of the two surfaces of the battery cell 110 and extends above the barrier layer 200 to cover a portion of the other surface of the battery cell 110. In this case, the top portion 110T of the battery cell 110 includes a first region P1 covered by the second barrier portion 200b and a second region P1 not covered by the second barrier portion 200b. In this case, the third barrier portion 200c can be formed only at one end of the battery cell 110 adjacent to the first region P1.

[0054] On the other hand, the first region P1 may be a portion of the top portion 110T of the battery cell 110 that is covered by the second barrier portion 200b in the longitudinal direction. The first region P1 and the second region P2 may be located at different positions in the longitudinal direction of the battery cell 110. The first region P1 may be adjacent to one end of the battery cell 110, and the second region P2 may be adjacent to the other end of the battery cell 110.

[0055] The barrier layer 200 according to this embodiment can guide the direction of the flame generated in the battery cell 110 through its asymmetric structure. For example, by forming the top portion 110T of the battery cell 110 including the first region P1 and the second region P2, the flame can be guided to the left side of the battery cell 110, as shown in Figure 14.

[0056] As described in the embodiments shown in Figures 5 to 7, the thickness of the first barrier portion 200a may be greater than the thickness of the second barrier portion 200b. The second barrier portion 200b can be made of a flexible material. A relatively thick first barrier portion 200a can enhance the flame retardant performance that blocks heat propagation between adjacent battery cells 110, while a relatively thin second barrier portion 200b can minimize the occurrence of a gap between the module frame housing the battery cell stack and the upper end of the battery cell 110. Furthermore, by forming the second barrier portion 200b of a flexible material, it can tightly cover the double-sided folding structure at the upper end of the battery cell 110. If a gap exists between the second barrier portion 200b covering the upper end of the battery cell 110 and the upper end of the module frame, the flame direction guidance will not be effective.

[0057] Referring to Figure 13, the battery cell stack 120 according to this embodiment can include a large number of battery cells 110 covered by a barrier layer 200. Since it is difficult to determine which of the stacked battery cells 110 will ignite, applying a large number of battery cells 110 covered by a barrier layer 200 allows for design that blocks flame induction and heat propagation.

[0058] On the other hand, one or more battery modules according to the embodiments of the present invention can be packaged in a pack case to form a battery pack.

[0059] The aforementioned battery modules and battery packs containing them can be applied to a variety of devices. Such devices include means of transport such as electric bicycles, electric vehicles, and hybrid vehicles, but the present invention is not limited thereto and is applicable to a variety of devices that can use battery modules and battery packs containing them, and this also falls within the scope of the present invention.

[0060] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art, utilizing the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention.

[0061] Furthermore, the present invention may also preferably include the following examples. [Section 1] A battery cell stack formed by stacking multiple battery cells, and The plurality of battery cells includes a barrier layer interposed between adjacent battery cells, The aforementioned barrier layer has varying thicknesses depending on its location, in a battery module. [Section 2] The battery module according to item 1, wherein the thickness of the barrier layer increases towards the edge, with reference to the surface facing the body portion of the battery cell. [Section 3] The battery module according to claim 1 or 2, wherein the barrier layer includes a first barrier portion covering the body portion of the battery cell and a second barrier portion extending from the first barrier portion and covering the top portion of the battery cell. [Section 4] The battery module according to item 3, wherein the thickness of the first barrier portion is greater than the thickness of the second barrier portion. [Section 5] The battery module according to item 4, wherein the second barrier portion is formed of a flexible material. [Section 6] The battery module according to item 5, wherein the top portion of the battery cell includes a first region covered by the second barrier portion and a second region not covered by the second barrier portion. [Section 7] The battery module according to any one of claims 3 to 6, wherein the barrier layer further includes a third barrier portion that covers the end of the battery cell in the area surrounding the electrode leads protruding from the battery cell. [Section 8] The battery module according to item 7, wherein the third barrier portion has an opening through which the electrode lead passes. [Section 9] The battery module according to any one of claims 1 to 8, wherein the barrier layer is formed of a flame-retardant material. [Section 10] The battery module according to item 9, wherein the barrier layer is formed of a silicone foam pad or a mica sheet. [Section 11] The battery module according to any one of claims 1 to 10, wherein the barrier layer comprises at least two or more layers, and at least two or more battery cells are located between two adjacent barrier layers. [Section 12] The battery module according to any one of claims 1 to 11, wherein the barrier layer covers one of the two surfaces of the battery cell and extends above the barrier layer to cover a portion of the other surface of the battery cell. [Section 13] The battery module according to item 12, wherein the barrier layer, by its asymmetric structure, guides the direction of the flame generated in the battery cell. [Section 14] A battery pack including a battery module as described in any one of items 1 through 13. [Explanation of symbols]

[0062] 110 battery cells 110B Body 110T Top section 120 Battery Cell Stack 200 barrier layer 200a First barrier section 200b Second barrier section 200c Third Barrier Section

Claims

1. A battery cell stack formed by stacking multiple battery cells, and The plurality of battery cells includes a barrier layer interposed between adjacent battery cells to delay heat propagation between the plurality of battery cells, The barrier layer includes a first barrier portion that covers the body portion of the battery cell and a second barrier portion that extends from the first barrier portion and covers the top portion of the battery cell. The second barrier portion is formed of a flexible material, A battery module in which the thickness of the first barrier portion is greater than the thickness of the second barrier portion.

2. The battery module according to claim 1, wherein the barrier layer has different thicknesses depending on its position.

3. The battery module according to claim 1 or 2, wherein the thickness of the first barrier portion increases towards the edge, with reference to the surface facing the body portion of the battery cell.

4. The battery module according to any one of claims 1 to 3, wherein the thickness of the first barrier portion is greater than the thickness of the second barrier portion.

5. A battery pack comprising a battery module according to any one of claims 1 to 4.

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