Battery module and battery pack including the same

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-reference 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 contents disclosed in the documents of said 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 slows down the rate of heat propagation between battery cells and a battery pack including the same. [Background technology]

[0003] The demand for secondary batteries as an energy source is rapidly increasing along with technological development and increasing demand for mobile devices. In particular, secondary batteries are attracting much attention as an energy source for power devices such as electric bicycles, electric cars, and hybrid electric cars, as well as for mobile devices such as mobile phones, digital cameras, laptops, and wearable devices.

[0004] While small mobile devices use one or more battery cells per device, medium to large devices such as automobiles require high output and large capacity, and therefore use medium to large battery modules in which multiple battery cells are electrically connected.

[0005] Since it is preferable that medium- to large-sized battery modules are manufactured to be as small and lightweight as possible, square batteries, pouch-type batteries, etc., which can be stacked with a high degree of integration and have a small weight relative to their capacity, are mainly used as battery cells for medium- to large-sized battery modules. Meanwhile, the battery module may include a module frame that has an open front and rear and stores the battery cell stack in an internal space to protect the battery cell stack from external impact, heat, or vibration.

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

[0007] 1 and 2, a conventional battery module includes a battery cell stack 12 in which a number of battery cells 11 are stacked in one direction, module frames 30, 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, 40 include a lower frame 30 that covers the bottom and both side surfaces of the battery cell stack 12, and an upper plate 40 that covers the top surface of the battery cell stack 12.

[0008] The battery cell stack 12 also includes fixing members 17 that fix the multiple battery cells 11 to one another, and the fixing members 17 are located at the center and / or ends of the battery cell stack 12. Furthermore, a compression pad 20 is located between a pair of adjacent battery cells in the battery cell stack 12.

[0009] 2 and 3, the compression pad 20 located in the conventional battery cell stack contacts the upper or lower surface of the battery cell 11. The compression pad 20 absorbs shocks that propagate to the adjacent battery cells 11. In addition, when the battery cell 11 ignites, the compression pad 20 can slow down the heat propagation speed depending on its thickness. However, when swelling occurs during the charging and discharging process of the battery cell 11, pressure and / or heat is applied to the compression pad 20. At this time, the compression rate of the conventional compression pad 20 varies depending on the position, and the physical properties of the compression pad 20 change accordingly. In addition, when the battery cell 110 ignites, a secondary cell ignition may occur due to external heat conduction caused by a flame generated in the battery cell 11 as well as heat conduction between the adjacent battery cells 11.

[0010] As a result, it is difficult for the conventional compression pad 20 alone to adequately slow down the heat propagation speed. Therefore, unlike the conventional technology, it is necessary to develop a battery module that can effectively slow down the heat propagation speed between battery cells even when the swelling phenomenon occurs. Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a battery module that effectively slows down the rate of heat propagation between battery cells, and a battery pack including the same.

[0012] However, the problem to be solved by the embodiments of the present invention is not limited to the above problem, and can be variously 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, the barrier layer having a thickness that varies depending on a position.

[0014] The thickness of the barrier layer may be increased toward the edge of the battery cell from the surface facing the body portion.

[0015] The barrier layer may include a first barrier portion covering a body portion of the battery cell, and a second barrier portion extending from the first barrier portion and covering a top portion of the battery cell.

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

[0017] The second barrier portion may be made of a flexible material.

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

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

[0020] The third barrier portion may have an opening through which the electrode lead passes.

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

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

[0023] At least two barrier layers may be included, and at least two 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 extend above the barrier layer to cover a portion of the other surface of the battery cell.

[0025] The barrier layer may guide the direction of a flame generated in the battery cell due to its asymmetric structure.

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

[0027] According to the embodiment, the barrier layer formed between a pair of adjacent battery cells in the battery cell stack functions as a flame-retardant material, thereby slowing the rate of heat propagation between the adjacent battery cells in the event of a fire in the battery cells.

[0028] In addition, by applying the barrier layer not only to the body portion of the battery cell but also extending from the body portion to the top portion and lead portion of the battery cell, the rate of heat propagation from a flame outside the cell to battery cells where no flame is occurring can be delayed.

[0029] In addition, by forming the barrier layer to have different thicknesses depending on the position, the compression rate of the barrier layer is reduced during cell swelling, thereby maximizing the performance of the barrier layer as a flame retardant material, and thus effectively delaying the heat propagation time between battery cells.

[0030] The effects of the present invention are not limited to those 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] FIG. 1 is a perspective view of a conventional battery module. [Diagram 2] FIG. 2 is a top view of a battery cell stack included in a conventional battery module. [Diagram 3] 3A is a top view of region A in FIG. 2, and FIG. 3B is a cross-sectional view taken along the cutting plane BB in FIG. [Figure 4] 1A-1C illustrate a method of forming a battery cell stack according to a comparative example. [Diagram 5] 1A-1C illustrate a method of forming a battery cell stack included in a battery module according to an embodiment of the present invention. [Figure 6] 6 is a perspective view showing one battery cell included in the battery cell stack of FIG. 5. FIG. [Figure 7] FIG. 6 is a front view showing a barrier layer encapsulating one battery cell included in the battery cell stack of FIG. 5. [Figure 8] 6 is a perspective view showing a battery cell stack formed by combining the battery cells of FIG. 5. FIG. [Figure 9] 13 is a plan view showing a barrier layer formed in a body portion of a battery cell included in a battery module according to another embodiment of the present invention. FIG. [Figure 10] 10 is a cross-sectional view taken along the line PP in FIG. 9. [Figure 11] FIG. 4 is a perspective view showing a barrier layer covering a battery cell according to another embodiment of the present invention. [Figure 12] 12 is a perspective view of the battery cell of FIG. 11 rotated 180 degrees and facing the opposite side. [Figure 13] 12 is a perspective view of a battery cell stack formed using the battery cell and barrier layer of FIG. 11. FIG. [Figure 14] 12 is a perspective view showing a path through which flames are discharged in the event of fire in the battery cell according to the embodiment of FIG. 11. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may, however, be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein.

[0033] In order to clearly describe the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0034] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, thicknesses are exaggerated to clearly express multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of explanation.

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

[0036] Also, throughout the specification, when a part "comprises" a certain element, this means that it may further include other elements, but not excluding other elements, unless specifically stated to the contrary.

[0037] Also, throughout the specification, "in a plane" means when the subject part is viewed from above, and "in cross section" means when the subject part is cut vertically and viewed from the side.

[0038] FIG. 4 is a diagram illustrating a method for forming a battery cell stack according to a comparative example.

[0039] Referring to FIG. 4, in the step of stacking the battery cells 11, the compression pads 20 are interposed between adjacent battery cells 11. After stacking the compression pads 20, stacking of the battery cells 11 can be continued again. At this time, the compression pads 20 can have a certain thickness. The compression pads 20 can prevent swelling of the cells and can delay heat propagation to a certain extent when the cells ignite. The battery cells 11 and the compression pads 20 are stacked to form a battery cell stack, and a battery module can be formed by a subsequent lead welding process and module frame process.

[0040] Fig. 5 is a diagram illustrating a method of forming a battery cell stack included in a battery module according to an embodiment of the present invention. Fig. 6 is a perspective view illustrating one battery cell included in the battery cell stack of Fig. 5. Fig. 7 is a front view illustrating a barrier layer that encapsulates one battery cell included in the battery cell stack of Fig. 5.

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

[0042] The battery cell 110 according to the present embodiment is preferably a pouch-type battery cell. For example, referring to FIG. 6, the battery cell 110 according to the present 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 a battery body 113, respectively. The battery cell 110 can be manufactured by bonding both ends 114a and 114b of the case 114 and both side surfaces 114c connecting them in a state in which an electrode assembly (not shown) is housed in the battery case 114. In other words, the battery cell 110 according to the present embodiment has a total of three sealing parts 114sa, 114sb, and 114sc, and the sealing parts 114sa, 114sb, and 114sc are structured to be sealed by a method such as heat fusion, and the remaining other side part is formed of a connecting part 115. The area between both ends 114a, 114b of the battery case 114 can be defined as the longitudinal direction of the battery cell 110, and the area between one side 114c connecting both ends 114a, 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 long along one edge of the battery cell 110, and a protrusion 110p of the battery cell 110 is formed at an end of the connecting portion 115. The protrusion 110p may be formed on at least one of both ends of the connecting portion 115 and protrude in a direction perpendicular to the extension direction of the connecting portion 115. The protrusion 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 in a laminate structure of a resin layer / metal foil film layer / resin layer. For example, if the surface of the battery case is formed of an O(oriented)-nylon layer, it tends to become slippery due to external impact when a large number of battery cells are stacked to form a medium- to large-sized battery module. Therefore, in order to prevent this and maintain a stable stacked structure of the battery cells, an adhesive member such as a pressure-sensitive adhesive such as double-sided tape or a chemical adhesive that bonds by a chemical reaction when bonded 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] 5 to 7, the barrier layer 200 according to the present 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 to cover 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 facing the y-axis direction in which the battery cells 110 are stacked, and the top portion 110T of the battery cell 110 may be a 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 may refer to an upper end portion based on the width direction of the battery cell 110.

[0046] At this time, the thickness of the first barrier portion 200a may be thicker than the thickness of the second barrier portion 200b. The second barrier portion 200b may be formed of a flexible material. The first barrier portion 200a may be formed relatively thick to enhance flame retardancy that blocks heat transfer between adjacent battery cells 110, and the second barrier portion 200b may be formed relatively thin to minimize the occurrence of gaps between a module frame that accommodates the battery cell stack and the upper ends of the battery cells 110. In addition, the second barrier portion 200b may be formed of a flexible material to closely cover the double-sided folding structure at the upper ends of the battery cells 110.

[0047] 7, the barrier layer 200 according to the present embodiment may further include a third barrier portion 200c covering an end of the battery cell 110 around the electrode leads 111, 112 protruding from the battery cell 110. The third barrier portion 200c may have an opening 200A through which the electrode leads 111, 112 pass.

[0048] FIG. 8 is a perspective view showing a battery cell stack formed by combining the battery cells of FIG.

[0049] 5 to 8, the battery module including the battery cell stack according to the present embodiment includes the first barrier portion 200a, and thus can block heat conduction from the ignited battery cell 110 to the adjacent battery cells 110 when the cell ignites. In addition, the battery module includes the second barrier portion 200b covering the top portion 110T and the third barrier portion 200c covering the end of the battery cell 110 around the electrode leads 111 and 112 in addition to the body portion 110B of the battery cell 110, and thus can offset the heat conduction effect of an external flame to the battery cells 110 where no flame is occurring. For example, referring to FIG. 8, when the first battery cell 110a ignites, the heat conduction due to the external flame can be offset by the second battery cell 110b to which the barrier layer 200 is applied.

[0050] Fig. 9 is a plan view showing a barrier layer formed in a body portion of a battery cell included in a battery module according to another embodiment of the present invention, and Fig. 10 is a cross-sectional view taken along line PP in Fig. 9.

[0051] 9 and 10, the barrier layer 200 according to the present embodiment may have different thicknesses depending on the positions. Specifically, the thickness of the barrier layer 200 becomes thicker toward the edge based on the surface facing the body part 110B of the battery cell 110. Conventionally, the compression pad 20 having the same thickness in all regions described in FIG. 4 is applied to the barrier layer without considering the cell swelling phenomenon caused by charging the battery cell 110. 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 the present embodiment, the barrier layer 200 may have different thicknesses depending on the regions in consideration of the cell swelling phenomenon. Therefore, the compression rate of the barrier layer 200 during the cell swelling phenomenon is reduced to maximize the performance as a flame retardant member, and thus the heat propagation time between the battery cells 110 may be effectively delayed. The description of the battery cell 110 described in FIGS. 5 to 8 may also be applied to the present embodiment. For example, the thickness of the first barrier part 200a described in FIGS. 5 to 8 may be formed to be different depending on the positions.

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

[0053] 11 and 12, the barrier layer 200 covers one of both sides of the battery cell 110 and extends above the barrier layer 200 to cover a portion of the other side 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 may be formed only at one end of the battery cell 110 adjacent to the first region P1.

[0054] Meanwhile, the first region P1 may be a portion of the top portion 110T of the battery cell 110 in the longitudinal direction that is covered by the second barrier portion 200b. 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 the present embodiment has an asymmetric structure and can guide the direction of a flame generated in the battery cell 110. As an example, by forming a top portion 110T of the battery cell 110 including a first region P1 and a second region P2, it is possible to guide a flame to the left side of the battery cell 110 as shown in FIG.

[0056] As described in the embodiment of FIGS. 5 to 7, the thickness of the first barrier portion 200a may be thicker than the thickness of the second barrier portion 200b. The second barrier portion 200b may be made of a flexible material. The first barrier portion 200a may be formed relatively thick to enhance flame retardancy that blocks heat transfer between adjacent battery cells 110, and the second barrier portion 200b may be formed relatively thin to minimize the occurrence of gaps between the module frame that accommodates the battery cell stack and the upper end of the battery cell 110. In addition, the second barrier portion 200b may be formed of a flexible material to closely cover the double-sided folding structure at the upper end of the battery cell 110. If there is a gap between the second barrier portion 200b that covers the upper end of the battery cell 110 and the upper end of the module frame, the flame direction may not be guided well.

[0057] 13, the battery cell stack 120 according to the present embodiment may include a number of battery cells 110 covered with a barrier layer 200. Since it is difficult to know which battery cell 110 among the stacked battery cells 110 may catch fire, a design that blocks flame induction and heat propagation can be achieved by applying a number of battery cells 110 covered with a barrier layer 200.

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

[0059] The battery module and the battery pack including the battery module may be applied to various devices, such as vehicles including electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and may be applied to various devices that can use the battery module and the battery pack including the battery module, which also fall within the scope of the present invention.

[0060] Although the 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 made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0061] Furthermore, the present invention preferably includes the following examples. [Section 1] 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; The barrier layer has a thickness that varies depending on the position of the battery module. [Section 2] Item 2. The battery module according to item 1, wherein the thickness of the barrier layer increases toward the edge based on the surface facing the body portion of the battery cell. [Section 3] Item 3. The battery module according to item 1 or 2, wherein the barrier layer includes a first barrier portion covering a body portion of the battery cell, and a second barrier portion extending from the first barrier portion and covering a top portion of the battery cell. [Section 4] Item 4. The battery module according to item 3, wherein the first barrier section is thicker than the second barrier section. [Section 5] Item 5. The battery module according to item 4, wherein the second barrier portion is made of a flexible material. [Section 6] Item 6. The battery module according to item 5, wherein a top portion of the battery cell includes a first region that is covered by the second barrier portion and a second region that is not covered by the second barrier portion. [Section 7] 7. The battery module according to any one of items 3 to 6, wherein the barrier layer further includes a third barrier portion that covers an end of the battery cell in a peripheral portion of an electrode lead protruding from the battery cell. [Section 8] Item 8. The battery module according to item 7, wherein the third barrier section has an opening through which the electrode lead passes. [Section 9] Item 9. The battery module according to any one of items 1 to 8, wherein the barrier layer is made of a flame-retardant material. [Section 10] Item 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] 11. The battery module according to any one of items 1 to 10, wherein at least two or more barrier layers are included, and at least two or more battery cells are located between two adjacent barrier layers among the barrier layers. [Section 12] Item 12. The battery module according to any one of items 1 to 11, wherein the barrier layer covers one of both sides of the battery cell and extends above the barrier layer to cover a part of the other side of the battery cell. [Section 13] Item 13. The battery module according to item 12, wherein the barrier layer guides the direction of a flame generated in the battery cell by an asymmetric structure. [Section 14] Item 14. A battery pack comprising the battery module according to any one of items 1 to 13. [Explanation of symbols]

[0062] 110 Battery Cell 110B Body 110T Top section 120 Battery cell stack 200 Barrier Layer 200a First Barrier Section 200b Second barrier section 200c 3rd Barrier Section

Claims

1. 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 to delay heat transfer between the plurality of battery cells; the barrier layer includes a first barrier portion covering a body portion of the battery cell, and a second barrier portion extending from the first barrier portion and covering a top portion of the battery cell; The second barrier portion is made of a flexible material.

2. The battery module according to claim 1 , wherein the barrier layer has a thickness that varies depending on the position.

3. The battery module according to claim 1 , wherein a thickness of the first barrier portion increases toward an edge of the first barrier portion with respect to a surface of the battery cell facing the body portion.

4. 4. The battery module according to claim 1, wherein the first barrier section is thicker than the second barrier section.

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

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