Heat propagation prevention end plate

Abstract

The present invention provides an end plate structure for covering the longitudinal end of a battery module, comprising: a first plate having a first hole passing through in the longitudinal direction; a second plate having a main body and a fastening portion extending outward in the longitudinal direction from the main body and disposed longitudinally inward relative to the first plate; and a thermal expansion member made of a thermally expandable material; wherein the fastening portion passes through the first hole to fasten the first plate to the main body, and the thermal expansion member expands in volume in the event of thermal runaway of the battery module.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0156396 filed on November 21, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to end plates that cover the front and rear of a battery module formed by accumulating pouch-type battery cells, and that retard or prevent heat propagation in the event of thermal runaway. [Background technology]

[0003] Secondary batteries, which are easily applicable to a wide range of products and have electrical properties such as high energy density, are commonly used not only in portable devices but also in electric vehicles or hybrid vehicles powered by electrical sources, power storage devices, etc. These secondary batteries are attracting attention as a new energy source because they not only have the primary advantage of dramatically reducing the use of fossil fuels, but also because they are environmentally friendly and improve energy efficiency by not producing any by-products from energy use.

[0004] While small mobile devices use one or two or three battery cells per device, medium to large devices such as automobiles require high output and large capacity, so medium to large battery modules, which electrically connect multiple battery cells, are used.

[0005] Since it is preferable to manufacture medium- to large-sized battery modules with small size and weight if possible, prismatic batteries and pouch-shaped batteries, which can be stacked with high density and have low weight relative to capacity, are mainly used as battery cells for medium- to large-sized battery modules.

[0006] 1 is a perspective view of a battery cell. Referring to FIG. 1, a typical pouch-type battery cell 21 includes an electrode assembly formed by stacking a plurality of positive and negative electrodes with a separator interposed therebetween, a pouch 211 that houses the electrode assembly and seals it, and an electrode lead 212 that extends from the electrode assembly and protrudes outside the pouch 211. A plurality of the battery cells 21 can be stacked to form a battery cell stack, and the battery cell stack can form a single battery module.

[0007] 2 and 3 are perspective and exploded perspective views showing the structure of a battery module. Referring to these drawings, the battery module (M) includes the battery cell stack 2, a pair of bus bar frames 1 connected to the front and rear surfaces of the battery cell stack 2, a frame 1 that is open at the front and rear and houses the battery cell stack, and a pair of end plates 3 that cover the front and rear of the frame 1, respectively.

[0008] 4 is an exploded perspective view showing the structure and coupling relationship of the end plate and bus bar frame. Referring to this, the electrode leads 212 protruding forward and backward from the battery cell stack 2 pass through slits 41 formed in the bus bar frame 1 and are welded to bus bars 42. The bus bars 42 connect the electrode leads 212 in parallel or in series to terminals 43. The terminals 43 are exposed to the outside through openings formed in the end plates 3, allowing the battery cell stack 2 to be connected to the outside.

[0009] Fig. 5 is a front view of an end plate, Fig. 6 is an enlarged cross-sectional view showing a portion of the end plate where a first hole is provided, and Fig. 7 is an enlarged cross-sectional view showing the occurrence of thermal runaway in Fig. 6. Referring to these drawings together with Fig. 4, the end plate 3 may be formed by joining a first plate 31 made of a metal material for covering the front and rear of the frame 1 and a second plate 32 made of a synthetic resin material that is injection-molded for insulation, at the front and rear. The first plate 31 is formed with a first hole 311, and the second plate 32 includes a main body portion 321 and a fastening portion 322. The fastening portion 322 is welded through the first hole 311 to fasten the first plate 31 and the main body portion 321 together. If thermal runaway occurs in the battery module (M), the second plate 32 made of a synthetic resin material may melt due to the heat, thereby opening the first hole 311 and risking the discharge of heat energy, gas, and flames from the inside of the battery module (M) to the outside through the first hole 311.

[0010] 22 is a perspective view showing a battery pack including a battery module. Referring to this, a plurality of the battery modules (M) can be housed in a single frame to form a battery pack (P). The battery modules (M) are arranged adjacent to each other with the end plates 3, to which the terminals 43 are exposed, facing each other. Therefore, in the event of thermal runaway in the battery module (M), the thermal energy, gas, and flames emitted through the first holes 311 can spread to adjacent battery modules, potentially causing a chain reaction of fires. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention was devised against the background of the conventional technology described above, and its object is to provide an end plate structure that can prevent thermal energy, gas, and flames generated during thermal runaway of a battery module from being discharged toward the end plate.

[0012] Yet another technical object of the present invention is to provide an end plate structure that does not require major changes to the structure of existing battery modules and that can economically delay or prevent chain reaction fires between battery modules in a battery pack.

[0013] The technical object of the present invention is not limited to the above-mentioned objects, and other unmentioned objects and advantages of the present invention can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it can be easily understood that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides an end plate structure that covers the longitudinal end of a battery module, comprising: a first plate having a first hole penetrating in the longitudinal direction; a second plate including a main body and a fastening portion extending outward in the longitudinal direction from the main body, the second plate being disposed longitudinally inward compared to the first plate; and a thermal expansion member made of a thermally expandable material; wherein the fastening portion passes through the first hole to fasten the first plate to the main body, and the thermal expansion member expands in volume in the event of thermal runaway of the battery module.

[0015] The fastening portion may be made of a material that melts in the event of thermal runaway of the battery module. For example, the fastening portion may be made of a synthetic resin material. Specifically, the fastening portion may penetrate the first hole and be welded, so that its longitudinal end portion expands radially outward to fasten the first plate and the main body together.

[0016] The thermal expansion member may include a second hole through which the fastening portion passes.

[0017] In one embodiment of the present invention, the fastening portion can pass through the first hole with the thermal expansion member covering it, thereby allowing the thermal expansion member to be interposed between the outer surface of the fastening portion and the inner surface of the first hole.

[0018] In one embodiment of the present invention, the thermal expansion member may be disposed along the length of the first hole such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion. In other words, the outer diameter of the thermal expansion member may correspond to the inner diameter of the first hole, the inner diameter of the thermal expansion member may correspond to the outer diameter of the fastening portion, and the length of the thermal expansion member may correspond to the length of the first hole.

[0019] In a modification of the embodiment of the present invention, the first hole may include a groove in a portion of an inner end section in the longitudinal direction thereof. The inner diameter of the groove may be larger than the inner diameter of the remaining section of the first hole. That is, the groove may have a shape that is recessed radially outward compared to the remaining section of the first hole.

[0020] In the first modification, the thermal expansion member may be provided along the length of the groove so that its outer circumferential surface corresponds to the inner circumferential surface of the groove and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion. In other words, the outer diameter of the thermal expansion member can correspond to the inner diameter of the groove, the inner diameter of the thermal expansion member can correspond to the outer diameter of the fastening portion, and the length of the thermal expansion member can correspond to the length of the groove.

[0021] Alternatively, in a second modified example, the thermal expansion member may include an insertion portion and an insertion interference portion. The insertion portion may be provided along the length of the first hole such that its outer peripheral surface corresponds to the inner peripheral surface of the first hole and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion, and the insertion interference portion may be provided along the length of the groove such that its outer peripheral surface corresponds to the inner peripheral surface of the groove and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion.

[0022] In another embodiment of the present invention, the end plate may further include a flame-retardant plate interposed between the first plate and the second plate along the length. The flame-retardant plate may have a third hole extending therethrough in the length direction. The fastening portion may pass through the third hole and the first hole in order to fasten the first plate, the flame-retardant plate, and the main body.

[0023] The fastening portion can pass through the third hole with the thermal expansion member covering it, thereby allowing the thermal expansion member to be interposed between the outer surface of the fastening portion and the inner surface of the third hole.

[0024] In another embodiment of the present invention, the third hole may have a larger inner diameter than the first hole. In this case, the thermal expansion member may be disposed along the length of the third hole such that its outer circumferential surface corresponds to the inner circumferential surface of the third hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion. In other words, the outer diameter of the thermal expansion member may correspond to the inner diameter of the third hole, the inner diameter of the thermal expansion member may correspond to the outer diameter of the fastening portion, and the length of the thermal expansion member may correspond to the length of the third hole.

[0025] In a modification of the other embodiment of the present invention, the thermal expansion member may also be interposed between the outer circumferential surface of the fastening portion and the inner circumferential surface of the first hole.

[0026] In a first modified example, the first hole and the second hole may have the same inner diameter. In this case, the thermal expansion member may be provided along the length of the first hole and the third hole so that its outer peripheral surface corresponds to the inner peripheral surfaces of the first hole and the third hole and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion. In other words, the outer diameter of the thermal expansion member can correspond to the inner diameters of the first hole and the third hole, the inner diameter of the thermal expansion member can correspond to the outer diameter of the fastening portion, and the length of the thermal expansion member can correspond to the lengths of the first hole and the third hole.

[0027] In a second modified example, the third hole may have an inner diameter larger than that of the first hole. In this case, the thermal expansion member may include an insertion portion and an insertion interference portion. The insertion portion may be provided along the length of the first hole so that its outer peripheral surface corresponds to the inner peripheral surface of the first hole and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion, and the insertion interference portion may be provided along the length of the third hole so that its outer peripheral surface corresponds to the inner peripheral surface of the third hole and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion.

[0028] The flame-retardant plate may be made of an electrically insulating material, that is, the flame-retardant plate may be made of a material that has flame retardancy and electrical insulation properties.

[0029] The thermal expansion member may be made of a foam material selected from the group consisting of soft urethane, light urethane, light polyurethane, and phosphorus-based flame retardant.

[0030] The present invention provides a battery module including the end plate, a battery pack including the battery module, and a vehicle structure including the battery pack. [Effects of the Invention]

[0031] The present invention provides an end plate structure that can prevent thermal energy, gas, and flames from being discharged to the end plate side in the event of thermal runaway of a battery module, by causing a thermal expansion member to expand and close the first hole and the second hole, even if the second plate melts.

[0032] The advantage of the present invention is that it can be implemented by simply adding a thermal expansion member without significantly changing the structure of an existing battery module.

[0033] Furthermore, according to the present invention, an end plate structure is provided in which the thermal expansion member includes an insertion interference portion, thereby accurately guiding the insertion position of the thermal expansion member.

[0034] In addition, the flame-retardant plate according to the present invention effectively insulates the end plate from the bus bar frame even when the second plate melts due to thermal runaway, thereby preventing further fires caused by short circuits.

[0035] In addition to the above, the present invention can achieve various other effects, which will be explained in each embodiment, or explanations of effects that can be easily inferred by ordinary engineers will be omitted. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. [Figure 2] FIG. 2 is a perspective view showing the structure of a battery module. [Figure 3] FIG. 2 is an exploded perspective view showing the structure of a battery module. [Figure 4] FIG. 2 is an exploded perspective view showing the structure and coupling relationship of an end plate and a bus bar frame. [Figure 5] FIG. [Figure 6] FIG. 4 is an enlarged cross-sectional view showing a portion of the end plate where a first hole is provided. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in FIG. 6. [Figure 8] FIG. 2 is an exploded perspective view showing the structure of an end plate according to the first embodiment of the present invention. [Figure 9] FIG. 3 is an enlarged cross-sectional view showing a portion where a first hole is provided in the end plate according to the first embodiment of the present invention. [Figure 10] FIG. 10 is an enlarged cross-sectional view showing a state in which thermal runaway occurs in FIG. 9. [Figure 11] FIG. 10 is an enlarged cross-sectional view showing a portion of an end plate according to a first modification of the first embodiment of the present invention, where a first hole is provided. [Figure 12] FIG. 12 is an enlarged cross-sectional view showing a state in which thermal runaway occurs in FIG. [Figure 13]FIG. 10 is an enlarged cross-sectional view showing a portion of an end plate according to a second modified example of the first embodiment of the present invention, where a first hole is provided. [Figure 14] FIG. 14 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in FIG. 13. [Figure 15] FIG. 10 is an exploded perspective view showing the structure of an end plate according to a second embodiment of the present invention. [Figure 16] FIG. 10 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to a second embodiment of the present invention. [Figure 17] FIG. 17 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in FIG. 16. [Figure 18] FIG. 10 is an enlarged cross-sectional view showing a portion of an end plate according to a first modification of the second embodiment of the present invention, where a first hole is provided. [Figure 19] FIG. 19 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in FIG. 18. [Figure 20] FIG. 10 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to a second modified example of the second embodiment of the present invention. [Figure 21] FIG. 21 is an enlarged cross-sectional view showing a state in which thermal runaway occurs in FIG. 20. [Figure 22] FIG. 2 is a perspective view showing a battery pack including a battery module. [Figure 23] FIG. 1 is a perspective view showing a vehicle including a battery pack. DETAILED DESCRIPTION OF THE INVENTION

[0037] The above-mentioned objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the technical concept of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0038] Although terms such as "first" and "second" are used to indicate various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0039] Throughout the specification, unless otherwise specified, each element may be singular or plural.

[0040] Hereinafter, when an arbitrary structure is arranged "on (or below)" a component or "above (or below)" a component, it means that the arbitrary structure is not only arranged in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure arranged above (or below) the component.

[0041] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0042] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprise" or "include" in this application should not be interpreted as including all of the multiple components or multiple steps described in the specification, but should be interpreted as meaning that some of the components or some of the steps may not be included, or that additional components or steps may be included.

[0043] In the entire specification, when it is stated that "A and / or B" this means A, B or A and B unless otherwise specified, and when it is stated that "C to D" this means C or more and D or less unless otherwise specified.

[0044] 2 and 3 are perspective and exploded perspective views showing the structure of a battery module. To solve the above problems, the present invention provides an end plate (3) covering an end of a battery module (M) in the longitudinal direction, the end plate including: a first plate having a first hole passing through in the longitudinal direction; a second plate having a body and a fastening portion extending outward in the longitudinal direction from the body and disposed inward in the longitudinal direction relative to the first plate; and a thermal expansion member made of a thermally expandable material; the fastening portion passes through the first hole to fasten the first plate to the body, and the thermal expansion member expands in volume during thermal runaway of the battery module.

[0045] The method for solving the problem of the present invention can be applied to end plates in which two plates are fastened together by passing a rivet rod made of synthetic resin through a through hole in the other plate and welding the two plates together. However, it will be understood from the following explanation that the method can also be applied to any battery cover or housing that has a hole that is opened when one of the components melts due to thermal runaway while it is normally being closed.

[0046] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[0047] [Example 1] 8 is an exploded perspective view showing the structure of an end plate according to Example 1 of the present invention. Referring to this, the end plate 3 according to this example may include a first plate 31, a second plate 32, and a thermal expansion member 33.

[0048] The first plate 31 may have a first hole 311 passing through in the length direction. A plurality of first holes 311 may be provided.

[0049] The second plate 32 may include a main body portion 321 and a fastening portion 322 extending outward in the longitudinal direction from the main body portion. The second plate 32 may be provided on the inner side in the longitudinal direction compared to the first plate 31.

[0050] The fastening portion 322 may penetrate the first hole 311 to fasten the first plate 31 and the body 321 to each other. The fastening portion 322 may be made of a material that melts when the battery module experiences thermal runaway. For example, the fastening portion 322 may be made of a thermoplastic synthetic resin material. In this case, the entire second plate 32, including the body 321 and the fastening portion 322, may be made of a synthetic resin material to provide insulation between the inside of the battery module and the first plate 31.

[0051] The fastening portion 322 may be a welded rivet that penetrates the first hole 311 and then is welded by heat on the outer longitudinal side of the first plate 31, so that its outer longitudinal end expands radially outward to fasten the first plate 31 and the main body portion 321 together.

[0052] The thermal expansion member 33 may be made of a material having thermal expansion properties, so that the volume of the thermal expansion member 33 may expand when the battery module experiences thermal runaway.

[0053] The thermal expansion member 33 may include a second hole 331 through which the fastening portion 322 passes.

[0054] In this embodiment, the fastening portion 322 can pass through the first hole 311 while being covered with the thermal expansion member 33, thereby allowing the thermal expansion member 33 to be interposed between the outer surface of the fastening portion 322 and the inner surface of the first hole 311.

[0055] 9 is an enlarged cross-sectional view showing a portion of an end plate where a first hole is provided according to a first embodiment of the present invention. Referring to this, the thermal expansion member 33 according to this embodiment may be provided along the length of the first hole 311 such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole 311 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. In other words, the outer diameter of the thermal expansion member 33 may correspond to the inner diameter of the first hole 311, the inner diameter of the thermal expansion member 33 may correspond to the outer diameter of the fastening portion 322, and the length of the thermal expansion member 33 may correspond to the length of the first hole 311.

[0056] The end plate 3 according to this embodiment may include: a first plate 31 having a first hole 311 penetrating in the longitudinal direction; a second plate 32 having a main body 321 disposed longitudinally inward relative to the first plate 31 and a fastening portion 322 extending longitudinally outward from the main body 321 and passing through the first hole 311 and then welded thereto, such that its outer end in the longitudinal direction expands radially outward, thereby fastening the first plate 31 and the main body 321 together; and a thermal expansion member 33 having a second hole 331 through which the fastening portion 322 passes, the outer diameter of which corresponds to the inner diameter of the first hole 311, the inner diameter of which corresponds to the outer diameter of the fastening portion 322, and the length of which corresponds to the length of the first hole 311, and which is interposed between the inner surface of the first hole 311 and the outer surface of the fastening portion 322 along the length of the first hole 311.

[0057] 10 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in FIG. 9. Referring to this, in the event of thermal runaway of the battery module, the fastening portion 322 may melt, causing thermal energy, gas, and flames within the battery module to be discharged to the outside and adjacent battery modules through the first hole 311, potentially resulting in heat propagation and a risk of ignition occurring between modules. In this case, the thermal expansion member 33 expands to close the first hole 311, thereby effectively preventing the thermal energy, gas, and flames within the battery module from being discharged through the first hole 311.

[0058] The advantage of this embodiment is that the same effect as above can be obtained simply by leaving the first hole 311 as it is or slightly enlarging its inner diameter, covering the fastening portion 322 with the thermal expansion member 33, and then inserting the fastening portion 322 into the first hole 311.

[0059] Fig. 11 is an enlarged cross-sectional view showing a portion of an end plate according to a first modified example of the first embodiment of the present invention where a first hole is provided, and Fig. 12 is an enlarged cross-sectional view showing a state in which thermal runaway occurs in Fig. 11. Referring to these drawings, the first hole 311 according to the first and second modified examples of this embodiment may include a groove 312 in a partial section of an inner end portion in the longitudinal direction. The inner diameter of the groove 312 may be larger than the inner diameter of the remaining section of the first hole 311. That is, the groove 312 may have a shape that is recessed radially outward compared to the remaining section of the first hole 311.

[0060] In the first modification, the thermal expansion member 33 may be provided along the length of the groove 312 so that its outer circumferential surface corresponds to the inner circumferential surface of the groove 312 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. In other words, the outer diameter of the thermal expansion member 33 can correspond to the inner diameter of the groove 312, and the inner diameter of the thermal expansion member 33 can correspond to the outer diameter of the fastening portion 322, and the length of the thermal expansion member 33 can correspond to the length of the groove 312. According to the first modification, the thermal expansion member 33 can be inserted simply by further machining the groove 312 into the existing first plate 31 provided with the first hole 311. This is economical because the length of the thermal expansion member 33 can be short. Furthermore, according to the first modification, there is a step at the boundary between the portion of the first hole 311 where the groove 312 is provided and the remaining portion, which limits the insertion depth of the thermal expansion member 33, which is advantageous in manufacturing.

[0061] 13 is an enlarged cross-sectional view showing a portion of an end plate according to a second modified example of the first embodiment of the present invention where a first hole is provided, and FIG. 14 is an enlarged cross-sectional view showing the occurrence of thermal runaway in FIG. 13 . Referring to these drawings, in the second modified example, the thermal expansion member 33 may include an insertion portion 332 and an insertion interference portion 333. The insertion portion 332 may be provided along the length of the first hole 311 such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole 311 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. The insertion interference portion 333 may be provided along the length of the groove portion 312 such that its outer circumferential surface corresponds to the inner circumferential surface of the groove portion 312 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. According to the second variant, the insertion depth of the thermal expansion member 33 is limited, which is advantageous in manufacturing, and since the thermal expansion member 33 is installed along the entire length of the first hole 311, the first hole 311 can be more reliably closed in the event of thermal runaway of the battery module.

[0062] [Example 2] The following description of the present embodiment, which is not otherwise mentioned, is the same as that of the first embodiment.

[0063] 15 is an exploded perspective view showing a structure of an end plate according to a second embodiment of the present invention. Referring to this, the end plate 3 according to this embodiment may further include a flame-retardant plate 34 interposed between the first plate 31 and the second plate 32 along the length direction. The flame-retardant plate 34 may be provided with a third hole 341 penetrating in the length direction. The fastening portion 322 may pass through the third hole 341 and the first hole 311 in order to fasten the first plate 31, the flame-retardant plate 34, and the main body portion 321 together.

[0064] The fastening portion 322 can pass through the third hole 341 with the thermal expansion member 33 covering it, thereby allowing the thermal expansion member 33 to be interposed between the outer surface of the fastening portion 322 and the inner surface of the third hole 341.

[0065] The flame-retardant plate 34 may be made of an electrically insulating material. That is, the flame-retardant plate 34 may be made of a material that is both flame-retardant and electrically insulating. If the main body 321 melts during thermal runaway of the battery module, there is a risk of a short circuit between the inside of the battery module and the first plate 31. Because the flame-retardant plate 34 is made of a flame-retardant material, it will not melt during thermal runaway. Because the flame-retardant plate 34 is made of an electrically insulating material, it can act as an insulating partition between the inside of the battery module and the first plate 31. This reduces the risk of a short circuit and subsequent fire during thermal runaway of the battery module.

[0066] The thermal expansion member 33 may be a foam material made of a material selected from the group consisting of soft urethane, lightweight urethane, lightweight polyurethane, and phosphorus-based flame retardant, but may be made of any material as long as its volume expands when the battery module experiences thermal runaway.

[0067] 16 is an enlarged cross-sectional view showing a portion of an end plate where a first hole is provided according to a second embodiment of the present invention. Referring to this, in this embodiment, the third hole 341 may have a larger inner diameter than the first hole 311. In this case, the thermal expansion member 33 may be provided along the length of the third hole 341 such that its outer circumferential surface corresponds to the inner circumferential surface of the third hole 341 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. In other words, the outer diameter of the thermal expansion member 33 may correspond to the inner diameter of the third hole 341, the inner diameter of the thermal expansion member 33 may correspond to the outer diameter of the fastening portion 322, and the length of the thermal expansion member 33 may correspond to the length of the third hole 341.

[0068] The end plate 3 according to this embodiment includes a first plate 31 having a first hole 311 penetrating in the lengthwise direction; a flame-retardant plate 34 made of an electrically insulating material and disposed inside the first plate 31 in the lengthwise direction and having a third hole 341 penetrating in the lengthwise direction; a main body 321 and a flame-retardant plate 34 extending outward in the lengthwise direction from the main body 321 and passing through the third hole 341 and the first hole 311, and being welded together so that the outer end of the flame-retardant plate 34 extends radially outward. and a second plate (32) including a fastening portion (322) extending outward and fastening the first plate (31), the flame-retardant plate (34) and the main body portion (321) together; and a thermal expansion member (33) having a second hole (331) through which the fastening portion (322) passes, the outer diameter of which corresponds to the inner diameter of the third hole (341), the inner diameter of which corresponds to the outer diameter of the fastening portion (322), and the length of which corresponds to the length of the third hole (341), and which is interposed along the length of the third hole (341) between the inner peripheral surface of the third hole (341) and the outer peripheral surface of the fastening portion (322).

[0069] 17 is an enlarged cross-sectional view showing the state in FIG. 16 where thermal runaway occurs. Referring to this, in the event of thermal runaway of the battery module, the fastening portion 322 may melt, causing thermal energy, gas, and flames within the battery module to escape to the outside and adjacent battery modules through the third hole 341 and the first hole 311, potentially resulting in heat propagation and a risk of ignition between modules. In this case, the thermal expansion member 33 expands to close the third hole 341, thereby effectively preventing thermal energy, gas, and flames from escaping through the third hole 341 and the first hole 311. Even if a portion of the fastening portion 322 remains in the first hole 311, the thermal expansion member 33 can completely close the third hole 341. Therefore, the thermal expansion member 33 can also maintain the first hole 311 closed despite being disposed only in the third hole 341.

[0070] The advantages of this embodiment are that the flame retardant plate 34 maintains insulation even in the event of thermal runaway, that no further processing is required for the first hole 311, and that both the first hole 311 and the third hole 341 can be closed with only a small amount of the thermal expansion member 33.

[0071] Fig. 18 is an enlarged cross-sectional view showing a portion where the first hole of the end plate according to a first modified example of Example 2 of the present invention is provided, and Fig. 19 is an enlarged cross-sectional view showing the state where thermal runaway occurs in Fig. 18. Referring to these drawings, the thermal expansion member 33 according to the first and second modified examples of this embodiment can also be interposed between the outer peripheral surface of the fastening portion 322 and the inner peripheral surface of the first hole 311.

[0072] In the first modified example, the first hole 311 and the second hole 331 may have the same inner diameter. In this case, the thermal expansion member 33 may be provided along the length of the first hole 311 and the third hole 341 so that its outer peripheral surface corresponds to the inner peripheral surfaces of the first hole 311 and the third hole 341 and its inner peripheral surface corresponds to the outer peripheral surface of the fastening portion 322. In other words, the outer diameter of the thermal expansion member 33 can correspond to the inner diameters of the first hole 311 and the third hole 341, and the inner diameter of the thermal expansion member 33 can correspond to the outer diameter of the fastening portion 322, and the length of the thermal expansion member 33 can correspond to the lengths of the first hole 311 and the third hole 341. The first modified example has the advantage that the inner diameters of the first hole 311 and the third hole 341 can both be easily punched out, and the third hole 341 and the first hole 311 can be reliably closed over their entire lengths.

[0073] FIG. 20 is an enlarged cross-sectional view showing a portion of an end plate according to a second modified example of the second embodiment of the present invention where a first hole is provided, and FIG. 21 is an enlarged cross-sectional view showing the occurrence of thermal runaway in FIG. 20 . Referring to these drawings, in the second modified example, the third hole 341 may have a larger inner diameter than the first hole 311. In this case, the thermal expansion member 33 may include an insertion portion 332 and an insertion interference portion 333. The insertion portion 332 may be provided along the length of the first hole 311 such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole 311 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. The insertion interference portion 333 may be provided along the length of the third hole 341 such that its outer circumferential surface corresponds to the inner circumferential surface of the third hole 341 and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion 322. According to the second modification, there is no need to process a separate groove, and by simply making the inner diameters of the first hole 311 and the third hole 341 different, it is possible to obtain manufacturing advantages by limiting the insertion depth.

[0074] The present invention also provides a battery module structure including the end plate.

[0075] 1 is a perspective view of a battery cell. Referring to FIG. 1, a pouch-type battery cell 21 to be installed in a medium- to large-sized battery module may include an electrode assembly formed by stacking a plurality of positive and negative electrodes with a separator interposed therebetween, a pouch 211 that houses and seals the electrode assembly, and an electrode lead 212 that extends from the electrode assembly and protrudes outside the pouch 211. A plurality of the battery cells 21 may be stacked to form a battery cell stack, and the battery cell stack may constitute a single battery module.

[0076] 2 and 3 are a perspective view and an exploded perspective view showing the structure of a battery module. Referring to these drawings, the battery module (M) may include the battery cell stack 2, a frame 1, a bus bar frame 1, and the end plate 3. The battery cell stack 2 may have its electrode leads 212 protruding in the lengthwise direction and housed in the frame 1, which is open on both sides in the lengthwise direction. In this case, the electrode leads 212 may pass through slits 41 provided in the bus bar frame 1 and be welded to a bus bar 42, and the end plate 3 may cover both exposed ends of the bus bar frame 1 in the lengthwise direction of the frame 1.

[0077] The present invention also provides a battery pack including the battery module and a vehicle structure including the same.

[0078] 22 and 23 are perspective views showing a battery pack including a battery module and a vehicle including the battery pack, respectively. Referring to these drawings, a plurality of the battery modules (M) can be housed in a single frame to form a battery pack (P). As described above, a plurality of the battery modules (M) may be arranged to face each other in the longitudinal direction. The battery pack (P) can be mounted on an electric vehicle (V) to function as a power source. The structures and manufacturing methods of these battery packs and electric vehicles are well known to those of ordinary skill in the art and will not be described in detail herein.

[0079] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. All modifications and variations within the meaning and scope of the following claims, as well as equivalent concepts, should be construed as being included within the scope of the present invention.

[0080] Although the present invention has been described above with reference to illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and various modifications may be made by those skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described in the above description of the embodiments of the present invention, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0081] M Battery Module 1 frame 2 Battery cell stack 21 Battery Cells 211 Pouch 212 Electrode Lead 4 Busbar Frame 41 Slit 42 Busbar Terminal 43 3 End Plate 31 Plate 1 311 Hole 1 312 Groove 32 Second Plate 321 Main body 322 Fastening part 33 Thermal expansion members 331 Hole 2 332 Insertion section 333 Insertion interference part 34 Flame retardant plate 341 Hole 3 P Battery pack V Automobile X length direction Y Thickness direction / Width direction Z height direction

Claims

1. An end plate that covers an end of the battery module in the longitudinal direction, a first plate having a first hole extending longitudinally therethrough; a second plate including a body portion and a fastening portion extending outward in a longitudinal direction from the body portion, the second plate being disposed inward in a longitudinal direction relative to the first plate; and a thermal expansion member made of a thermally expandable material; the fastening portion passes through the first hole and fastens the first plate and the main body portion; the thermal expansion member expands in volume when the battery module experiences thermal runaway; End plate.

2. the fastening portion is made of a material that melts in the event of thermal runaway of the battery module; The end plate of claim 1 .

3. The fastening portion is made of a synthetic resin and is a welding rivet that is welded after passing through the first hole. The end plate according to claim 2 .

4. The thermal expansion member is a second hole through which the fastening portion passes; The fastening portion is disposed between an outer peripheral surface of the fastening portion and an inner peripheral surface of the first hole. The end plate according to claim 2 .

5. The thermal expansion member is provided along the length of the first hole such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion. The end plate according to claim 4 .

6. the first hole includes a groove portion in a partial section of an inner end portion in a longitudinal direction thereof, the groove portion having an inner diameter larger than that of the remaining section; The thermal expansion member is provided along the length of the groove so that its outer circumferential surface corresponds to the inner circumferential surface of the groove and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion. The end plate according to claim 4 .

7. the first hole includes a groove portion in a partial section of an inner end portion in a longitudinal direction thereof, the groove portion having an inner diameter larger than that of the remaining section; The thermal expansion member is an insertion portion disposed along the length of the first hole such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion; an insertion interference portion provided along the length of the groove portion such that its outer circumferential surface corresponds to the inner circumferential surface of the groove portion and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion, The end plate according to claim 4 .

8. a flame-retardant plate having a third hole passing through in the longitudinal direction and interposed between the first plate and the second plate along the longitudinal direction; the fastening portion passes through the third hole and the first hole in sequence to fasten the first plate, the flame-retardant plate, and the main body portion together; The end plate of claim 1 .

9. the fastening portion is made of a material that melts in the event of thermal runaway of the battery module; The end plate according to claim 8 .

10. The fastening portion is a welding rivet made of synthetic resin and welded after passing through the third hole and the first hole in sequence. The end plate according to claim 9.

11. The thermal expansion member is a second hole through which the fastening portion passes; a third hole provided between an outer peripheral surface of the fastening portion and an inner peripheral surface of the third hole; The end plate according to claim 9.

12. The third hole has an inner diameter larger than that of the first hole, the thermal expansion member is provided along the length of the third hole such that its outer circumferential surface corresponds to the inner circumferential surface of the third hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion; The end plate of claim 11.

13. The thermal expansion member is also interposed between an outer peripheral surface of the fastening portion and an inner peripheral surface of the first hole. The end plate of claim 11.

14. the first hole and the third hole have the same inner diameter; the thermal expansion member is provided along the length of the first hole and the third hole such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole and the third hole, and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion; The end plate of claim 13.

15. The third hole has an inner diameter larger than that of the first hole, The thermal expansion member is an insertion portion disposed along the length of the first hole such that its outer circumferential surface corresponds to the inner circumferential surface of the first hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion; an insertion interference portion provided along the length of the third hole such that its outer circumferential surface corresponds to the inner circumferential surface of the third hole and its inner circumferential surface corresponds to the outer circumferential surface of the fastening portion; The end plate of claim 13.

16. The flame-retardant plate is made of an electrically insulating material. The end plate according to claim 8 .

17. The thermal expansion member is a foam material made of a material selected from the group consisting of soft urethane, light urethane, light polyurethane, and phosphorus-based flame retardant. The end plate of claim 1 .

18. An end plate according to any one of claims 1 to 17, Battery module.

19. A battery module comprising: Battery pack.

20. 20. A battery pack comprising: car.

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