End plate wherein thermal propagation is prevented

Abstract

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

Description

Technology Field

[0001] The present invention relates to an end plate covering the front and rear of a battery module formed by integrating pouch-type battery cells, wherein the end plate delays or prevents heat propagation during thermal runaway. Background Technology

[0002] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles or hybrid vehicles powered by electric sources, and power storage devices. These secondary batteries are attracting attention as a new energy source for enhancing eco-friendliness and energy efficiency, not only for the primary advantage of drastically reducing the use of fossil fuels but also because they generate no by-products from energy use.

[0003] 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. Therefore, medium-to-large battery modules consisting of multiple battery cells electrically connected are used.

[0004] Since it is desirable for medium-to-large battery modules to be manufactured with the smallest possible size and weight, prismatic and pouch-type batteries, which can be stacked with high integration density and have a low weight-to-capacity ratio, are mainly used as battery cells for medium-to-large battery modules.

[0005] FIG. 1 is a perspective view of a battery cell. Referring thereto, a typical pouch-type battery cell (21) comprises an electrode assembly formed by stacking a plurality of positive and negative electrodes with a separator interposed therebetween, a pouch (211) that accommodates 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.

[0006] FIGS. 2 and FIGS. 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) includes the battery cell stack (2), a pair of busbar 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 accommodates the battery cell stack, and a pair of end plates (3) that cover the front and rear surfaces of the frame (1).

[0007] FIG. 4 is an exploded perspective view showing the structure and connection relationship of the end plate and the busbar frame. Referring to this, the electrode lead (212) protruding forward and backward from the battery cell stack (2) passes through a slit (41) provided in the busbar frame (1) and is welded to the busbar (42). The busbar (42) connects the electrode lead (212) to the terminal (43) in parallel or in series. The terminal (43) is exposed to the outside through an opening provided in the end plate (3) so as to connect the battery cell stack (2) to the outside.

[0008] FIG. 5 is a front view of the end plate, FIG. 6 is an enlarged cross-sectional view showing the area where the first hole is provided in the end plate, and FIG. 7 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 6. Referring to FIG. 4 and these drawings together, the end plate (3) may be formed by combining a first plate (31) made of metal material to cover the front and rear of the frame (1), and a second plate (32) made of synthetic resin material that is injection-molded for insulation. A first hole (311) is provided in the first plate (31), and the second plate (32) is composed of a main body part (321) and a fastening part (322), and the fastening part (322) is welded through the first hole (311) to fasten the first plate (31) and the main body part (321) to each other. If thermal runaway occurs in the battery module (M), the second plate (32), made of synthetic resin material, may melt due to heat, and consequently, the first hole (311) may open, and there is a risk that thermal energy, gas, and flames may be discharged from inside the battery module (M) to the outside through the first hole (311).

[0009] FIG. 22 is a perspective view showing a battery pack including battery modules. Referring to this, a plurality of battery modules (M) can be housed in a single frame to form a battery pack (P). At this time, the battery modules (M) are arranged adjacent to each other with the end plates (3) where the terminals (43) are exposed facing each other. Accordingly, when the battery modules (M) undergo thermal runaway, the thermal energy, gas, and flames discharged through the first hole (311) can propagate to adjacent battery modules, and consequently, there is a risk of a chain reaction of ignition. The problem to be solved

[0010] The present invention was conceived against the background of the prior art described above, and aims to provide a structure for an end plate capable of preventing thermal energy, gas, and flames generated during thermal runaway of a battery module from being discharged toward the end plate.

[0011] Another technical objective of the present invention is to provide a structure of an end plate that can economically delay or prevent sequential ignition between battery modules within a battery pack without significantly altering the structure of existing battery modules.

[0012] The technical problems of the present invention are not limited to the purposes mentioned above, and other unmentioned purposes and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0013] To solve the above problem, the present invention provides an end plate covering a longitudinal end of a battery module, comprising: a first plate having a first hole formed along the longitudinal direction; a main body portion; a fastening portion extending longitudinally outward from the main body portion; a second plate formed longitudinally inward relative to the first plate; and a thermal expansion member made of a thermally expandable material, wherein the fastening portion penetrates the first hole to fasten the first plate and the main body portion, and the thermal expansion member expands in volume upon thermal runaway of the battery module.

[0014] The above-mentioned fastening portion may be made of a material that melts upon thermal runaway of the battery module. For example, the fastening portion may be made of a synthetic resin material. Specifically, the fastening portion may be welded after penetrating the first hole, thereby extending its longitudinal end outward in the radial direction to fasten the first plate and the main body portion to each other.

[0015] The above thermal expansion member may include a second hole through which the above fastening part penetrates.

[0016] In one embodiment of the present invention, the fastening portion may penetrate the first hole while covered with the thermal expansion member, and accordingly, the thermal expansion member may be interposed between the outer surface of the fastening portion and the inner surface of the first hole.

[0017] In one embodiment of the present invention, the thermal expansion member may be provided along the length of the first hole such that its outer surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening part. 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 part, and the length of the thermal expansion member may correspond to the length of the first hole.

[0018] In a modified embodiment of one embodiment of the present invention, the first hole may include a groove portion in a portion of its longitudinal inner end. The inner diameter of the groove portion may be larger than the inner diameter of the remaining portion of the first hole. That is, the groove portion may have a shape that is recessed radially outward compared to the remaining portion of the first hole.

[0019] In the first modified example, the thermal expansion member may be provided along the length of the groove portion such that its outer surface corresponds to the inner surface of the groove portion and its inner surface corresponds to the outer surface of the fastening portion. In other words, the outer diameter of the thermal expansion member may correspond to the inner diameter of the groove portion, 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 groove portion.

[0020] 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 surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening portion, and the insertion interference portion may be provided along the length of the groove portion such that its outer surface corresponds to the inner surface of the groove portion and its inner surface corresponds to the outer surface of the fastening portion.

[0021] In another embodiment of the present invention, the end plate may additionally include a flame-retardant plate interposed between the first plate and the second plate along the longitudinal direction. The flame-retardant plate may be provided with a third hole along the longitudinal direction. The fastening portion may fasten the first plate, the flame-retardant plate, and the main body portion by sequentially penetrating the third hole and the first hole.

[0022] The above fastening portion can penetrate the third hole while covered with the thermal expansion member, and accordingly, the thermal expansion member can be interposed between the outer surface of the fastening portion and the inner surface of the third hole.

[0023] In another embodiment of the present invention, the inner diameter of the third hole may be larger than that of the first hole. In this case, the thermal expansion member may be provided along the length of the third hole such that its outer surface corresponds to the inner surface of the third hole and its inner surface corresponds to the outer surface of the fastening part. 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 part, and the length of the thermal expansion member may correspond to the length of the third hole.

[0024] In a variation of another embodiment of the present invention, the thermal expansion member may also be interposed between the outer surface of the fastening portion and the inner surface of the first hole.

[0025] In the 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 such that its outer surface corresponds to the inner surface of the first hole and the third hole, and its inner surface corresponds to the outer surface of the fastening part. In other words, the outer diameter of the thermal expansion member may correspond to the inner diameter of the first hole and the third hole, the inner diameter of the thermal expansion member may correspond to the outer diameter of the fastening part, and the length of the thermal expansion member may correspond to the length of the first hole and the third hole.

[0026] In the second modified example, the inner diameter of the third hole may be 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 such that its outer surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening portion, and the insertion interference portion may be provided along the length of the third hole such that its outer surface corresponds to the inner surface of the third hole and its inner surface corresponds to the outer surface of the fastening portion.

[0027] The flame-retardant plate may be made of an electrically insulating material. That is, the flame-retardant plate may be made of a material having flame retardancy and electrical insulation properties.

[0028] The above thermal expansion member may be a foam material made of a material selected from the group including soft urethane, hard urethane, hard polyurethane, and phosphorus-based flame retardants.

[0029] The present invention provides a battery module including the end plate, a battery pack including the battery module, and a structure of a vehicle including the battery pack. Effects of the invention

[0030] The present invention can provide a structure for an end plate that prevents thermal energy, gas, and flame from being discharged toward the end plate by the thermal expansion member expanding to close the first hole and the second hole, even if the second plate melts during thermal runaway of the battery module.

[0031] The advantage of the present invention is that it can be implemented simply by adding a thermal expansion member without significantly changing the structure of the existing battery module.

[0032] In addition, according to the present invention, a structure of an end plate is provided in which the insertion position of the thermal expansion member is accurately guided by including an insertion interference portion in the thermal expansion member.

[0033] In addition, the flame-retardant plate according to the present invention can effectively insulate the end plate and the busbar frame even when the second plate is melted due to thermal runaway, thereby suppressing ignition caused by an additional short circuit.

[0034] In addition to the above, the present invention may have various other effects, which are described in each embodiment, or effects that can be easily inferred by a person skilled in the art, etc., will be omitted. Brief explanation of the drawing

[0035] Figure 1 is a perspective view of a battery cell. Figures 2 and 3 are a perspective view and an exploded perspective view showing the structure of a battery module. FIG. 4 is an exploded perspective view showing the structure and connection relationship of the end plate and busbar frame. 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 appearance of thermal runaway occurring in FIG. 6. FIG. 8 is an exploded perspective view showing the structure of an end plate according to Example 1 of the present invention. FIG. 9 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to Embodiment 1 of the present invention, and FIG. 10 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 9. FIG. 11 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to a first modified example of Embodiment 1 of the present invention, and FIG. 12 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 11. FIG. 13 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 Example 1 of the present invention, and FIG. 14 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 13. FIG. 15 is an exploded perspective view showing the structure of an end plate according to Example 2 of the present invention. FIG. 16 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to Embodiment 2 of the present invention, and FIG. 17 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 16. FIG. 18 is an enlarged cross-sectional view showing a portion where a first hole is provided in an end plate according to a first modified example of Embodiment 2 of the present invention, and FIG. 19 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 18. FIG. 20 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 Embodiment 2 of the present invention, and FIG. 21 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 20. FIGS. 22 and FIGS. 23 are perspective views showing a battery pack including a battery module and a vehicle including a battery pack, respectively. Specific details for implementing the invention

[0036] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0037] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0038] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0039] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0040] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0041] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0042] Additionally, singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0043] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0044] FIGS. 2 and FIGS. 3 are a perspective view and an exploded perspective view showing the structure of a battery module. Referring to these drawings, in order to solve the above problem, the present invention provides an end plate (3) covering a longitudinal end of a battery module (M), comprising a first plate having a first hole along the longitudinal direction, a main body part, and a fastening part extending longitudinally outward from the main body part, a second plate having a longitudinally inward side relative to the first plate, and a thermal expansion member made of a thermally expandable material, wherein the fastening part penetrates the first hole to fasten the first plate and the main body part, and the thermal expansion member expands in volume during thermal runaway of the battery module.

[0045] The solution to the problem of the present invention can be applied to an end plate in which two plates are joined together by welding a rivet rod made of synthetic resin material provided on one plate through a through hole provided on another plate; however, it will be understood from the following description that, generally, it can be applied to any battery cover or housing in which a hole is provided that is normally blocked by a certain member and becomes open when said member melts due to thermal runaway.

[0046] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

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

[0048] The first plate (31) may be provided with a first hole (311) along the longitudinal direction. Multiple first holes (311) may be provided.

[0049] The second plate (32) may include a main body portion (321) and a fastening portion (322) extending outwardly in the longitudinal direction from the main body portion. The second plate (32) may be provided inwardly in the longitudinal direction relative to the first plate (31).

[0050] The above fastening portion (322) can pass through the first hole (311) to fasten the first plate (31) and the main body portion (321) to each other. The fastening portion (322) may be made of a material that melts during thermal runaway of the battery module. 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 main body portion (321) and the fastening portion (322), may be made of a synthetic resin material to provide insulation between the interior of the battery module and the first plate (31).

[0051] The above fastening portion (322) may be a welded rivet that fastens the first plate (31) and the main body portion (321) together by being welded by heat from the longitudinal outer side of the first plate (31) after penetrating the first hole (311), so that the longitudinal outer end is extended radially outward.

[0052] The above thermal expansion member (33) may be made of a material having thermal expansion properties. Accordingly, the volume of the above thermal expansion member (33) may expand during thermal runaway of the battery module.

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

[0054] In this embodiment, the fastening portion (322) can penetrate the first hole (311) while covered with the thermal expansion member (33), and accordingly, the thermal expansion member (33) can be interposed between the outer surface of the fastening portion (322) and the inner surface of the first hole (311).

[0055] FIG. 9 is an enlarged cross-sectional view showing the portion where the first hole is provided in the end plate according to Embodiment 1 of the present invention. Referring thereto, the thermal expansion member (33) according to the present embodiment may be provided along the length of the first hole (311) such that its outer surface corresponds to the inner surface of the first hole (311) and its inner surface corresponds to the outer surface of the fastening part (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 part (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 the present embodiment comprises: a first plate (31) having a first hole (311) along the longitudinal direction; and a second plate (32) having a fastening part (322) which is provided on the longitudinal inner side relative to the first plate (31), extends longitudinally outward from the main body part (321) and penetrates the first hole (311) and is welded, thereby extending the longitudinally outward end of the fastening part outwardly to fasten the first plate (31) and the main body part (321) to each other. A second hole (331) through which the fastening part (322) passes is provided, 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 part (322), and the length of which corresponds to the length of the first hole (311), and the thermal expansion member (33) is interposed along the length of the first hole (311) between the inner surface of the first hole and the outer surface of the fastening part (322).

[0057] FIG. 10 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 9. Referring to this, when thermal runaway occurs in the battery module, the fastening part (322) may melt, and as a result, thermal energy, gas, and flames inside the battery module may be discharged through the first hole (311) toward the outside and neighboring battery modules, thereby creating a risk of heat propagation and chain ignition between modules. At this time, the thermal expansion member (33) can expand to close the first hole (311), thereby effectively preventing thermal energy, gas, and flames inside the battery module from being discharged through the first hole (311).

[0058] The advantage of the present embodiment is that the above-described effect can be obtained simply by leaving the first hole (311) as is or slightly expanding its inner diameter, covering the fastening part (322) with the thermal expansion member (33), and then inserting the fastening part (322) into the first hole (311).

[0059] FIG. 11 is an enlarged cross-sectional view showing the portion where the first hole of the end plate is provided according to the first modified example of Embodiment 1 of the present invention, and FIG. 12 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 11. Referring to these drawings, the first hole (311) according to the first modified example and the second modified example of the present embodiment may include a groove (312) in a portion of the inner end in the longitudinal direction. The inner diameter of the groove (312) may be larger than the inner diameter of the remaining portion of the first hole (311). That is, the groove (312) may have a shape that is recessed radially outward compared to the remaining portion of the first hole (311).

[0060] In the first modified example, the thermal expansion member (33) may be formed along the length of the groove (312) such that its outer surface corresponds to the inner surface of the groove (312) and its inner surface corresponds to the outer surface of the fastening part (322). In other words, the outer diameter of the thermal expansion member (33) may correspond to the inner diameter of the groove (312), the inner diameter of the thermal expansion member (33) may correspond to the outer diameter of the fastening part (322), and the length of the thermal expansion member (33) may correspond to the length of the groove (312). According to the first modified example, it is possible to insert the thermal expansion member (33) by simply additionally machining the groove (312) into the existing first plate (31) in which the first hole (311) is provided, and it is economical because the length of the thermal expansion member (33) can be short. In addition, according to the first variant, there is a step difference at the boundary between the portion where the groove (312) is provided in the first hole (311) and the remaining portion, so the insertion depth of the thermal expansion member (33) is limited, which is advantageous in manufacturing.

[0061] FIG. 13 is an enlarged cross-sectional view showing the portion where the first hole of the end plate is provided according to the second modified example of Embodiment 1 of the present invention, and FIG. 14 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring 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 surface corresponds to the inner surface of the first hole (311) and its inner surface corresponds to the outer surface of the fastening portion (322), and the insertion interference portion (333) may be provided along the length of the groove portion (312) such that its outer surface corresponds to the inner surface of the groove portion (312) and its inner surface corresponds to the outer 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 for manufacturing, and since the thermal expansion member (33) is provided 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] The following description regarding parts not separately mentioned in this embodiment is the same as that in Example 1 above.

[0063] FIG. 15 is an exploded perspective view showing the structure of an end plate according to Embodiment 2 of the present invention. Referring thereto, the end plate (3) according to the present embodiment may additionally include a flame-retardant plate (34) interposed between the first plate (31) and the second plate (32) along the longitudinal direction. A third hole (341) along the longitudinal direction may be provided in the flame-retardant plate (34). The fastening part (322) may fasten the first plate (31), the flame-retardant plate (34), and the main body part (321) by sequentially penetrating the third hole (341) and the first hole (311).

[0064] The above fastening part (322) can penetrate the third hole (341) while covered with the thermal expansion member (33), and accordingly, the thermal expansion member (33) can be interposed between the outer surface of the fastening part (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 possesses both flame-retardant and electrically insulating properties. When the main body (321) melts during a thermal runaway of the battery module, there is a risk that the inside of the battery module and the first plate (31) will cause a short circuit. The flame-retardant plate (34) may not melt even during a thermal runaway because it is made of a flame-retardant material, and it may act as an insulating barrier between the inside of the battery module and the first plate (31) because it is made of an electrically insulating material. By doing so, the risk of a short circuit and additional ignition caused by it during a thermal runaway of the battery module can be reduced.

[0066] The above thermal expansion member (33) may be a foam material made of a material selected from the group including soft urethane, hard urethane, hard polyurethane, and phosphorus-based flame retardant. However, the above thermal expansion member (33) may be made of any material as long as its volume expands during thermal runaway of the battery module.

[0067] FIG. 16 is an enlarged cross-sectional view showing the portion where the first hole is provided in the end plate according to Embodiment 2 of the present invention. Referring to this, in this embodiment, the inner diameter of the third hole (341) may be larger than that of the first hole (311). At this time, the thermal expansion member (33) may be provided along the length of the third hole (341) such that its outer surface corresponds to the inner surface of the third hole (341) and its inner surface corresponds to the outer surface of the fastening part (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 part (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 the present embodiment comprises: a first plate (31) having a first hole (311) along the longitudinal direction; a flame-retardant plate (34) having a third hole (341) along the longitudinal direction provided inwardly relative to the first plate (31) and made of an electrically insulating material; and a second plate (32) having a fastening part (322) having a main body part (321) and a main body part (321) extending outwardly in the longitudinal direction from the main body part (321) and the main body part (321), and which is welded after penetrating the third hole and the first hole (311), thereby extending outwardly in the longitudinal direction so that the outer end of the fastening part (322) is extended outwardly in the longitudinal direction to fasten the first plate (31), the flame-retardant plate (34), and the main body part (321) to each other. A second hole (331) through which the fastening part (322) passes is provided, 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 part (322), and the length of which corresponds to the length of the third hole (341), and may include a thermal expansion member (33) interposed along the length of the third hole (341) between the inner surface of the third hole and the outer surface of the fastening part (322).

[0069] FIG. 17 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 16. Referring to this, when thermal runaway occurs in the battery module, the fastening part (322) may melt, and as a result, thermal energy, gas, and flames inside the battery module may be discharged to the outside and to neighboring battery modules through the third hole (341) and the first hole (311), thereby creating a risk of heat propagation and chain ignition between modules. At this time, the thermal expansion member (33) can expand to close the third hole (341), thereby effectively preventing thermal energy, gas, and flames inside the battery module from being discharged through the third hole (341) and the first hole (311). At this time, since the thermal expansion member (33) may completely close the third hole (341) even while a part of the above-mentioned fastening part (322) still remains within the first hole (311), the first hole (311) may also remain closed even though the thermal expansion member (33) is provided only in the third hole (341).

[0070] The advantages of the present embodiment are that insulation is maintained even during thermal runaway due to the flame-retardant plate (34), that no additional 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 the portion where the first hole of the end plate is provided according to the first modified example of Embodiment 2 of the present invention, and FIG. 19 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 18. Referring to these drawings, the thermal expansion member (33) according to the first modified example and the second modified example of the present invention may also be interposed between the outer surface of the fastening portion (322) and the inner 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. At this time, the thermal expansion member (33) may be provided along the length of the first hole (311) and the third hole (341) such that its outer surface corresponds to the inner surface of the first hole (311) and the third hole (341), and its inner surface corresponds to the outer surface of the fastening part (322). In other words, the outer diameter of the thermal expansion member (33) may correspond to the inner diameter of the first hole (311) and the third hole (341), the inner diameter of the thermal expansion member (33) may correspond to the outer diameter of the fastening part (322), and the length of the thermal expansion member (33) may correspond to the length of the first hole (311) and the third hole (341). According to the first modified example, the inner diameters of the first hole (311) and the third hole (341) are easily drilled together, and there is an advantage that the third hole (341) and the first hole (311) can be securely closed along their entire lengths.

[0073] FIG. 20 is an enlarged cross-sectional view showing the portion where the first hole of the end plate is provided according to the second modified example of Embodiment 2 of the present invention, and FIG. 21 is an enlarged cross-sectional view showing the appearance of thermal runaway occurring in FIG. 20. Referring to these drawings, in the second modified example, the inner diameter of the third hole (341) may be larger than that of the first hole (311). At this time, 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 surface corresponds to the inner surface of the first hole (311) and its inner surface corresponds to the outer surface of the fastening portion (322), and the insertion interference portion (333) may be provided along the length of the third hole (341) such that its outer surface corresponds to the inner surface of the third hole (341) and its inner surface corresponds to the outer surface of the fastening portion (322). According to the second modified example, without the need to process a separate groove, a manufacturing advantage due to the limitation of insertion depth can be obtained simply by making the inner diameters of the first hole (311) and the third hole (341) different.

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

[0075] FIG. 1 is a perspective view of a battery cell. Referring thereto, a pouch-type battery cell (21) embedded in a medium-to-large 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 accommodates 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] FIGS. 2 and FIGS. 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 busbar frame (1), and the end plate (3). The battery cell stack (2) may be received in the frame (1), which is open on both sides in the longitudinal direction, with its electrode lead (212) protruding in the longitudinal direction. At this time, the electrode lead (212) may be welded to the busbar (42) by passing through a slit (41) provided in the busbar frame (1), and the end plate (3) may cover both sides in the longitudinal direction of the frame (1) where the busbar frame (1) is exposed.

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

[0078] FIGS. 22 and FIGS. 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 battery modules (M) may be housed within a single frame to form a battery pack (P). As described above, the plurality of battery modules (M) may be arranged to face each other in the longitudinal direction. The battery pack (P) may be mounted on an electric vehicle (V) to serve as a power source. The structure and manufacturing method of such a battery pack and an electric vehicle are widely known to those skilled in the art and will not be described in detail in this specification.

[0079] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0080] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized. Explanation of the symbols

[0081] M: Battery module 1: Frame 2: Battery cell stack 21: Battery cell 211: Pouch 212: Electrode Lead 4: Busbar frame 41: Slit 42: Busbar 43: Terminal 3: End plate 31: First plate 311: Hall 1 312: Homeboo 32: Second plate 321: Main body 322: Connecting part 33: Thermal expansion member 331: 2nd hole 332: Insert 333: Insertion interference part 34: Flame-retardant plate 341: 3rd hole P: Battery pack V: Car X: Length direction Y: Thickness direction / Width direction Z: Height direction

Claims

Claim 1 An end plate covering a longitudinal end of a battery module comprises: a first plate having a first hole along the longitudinal direction; a second plate having a main body and a fastening portion extending longitudinally outward from the main body and having a second plate having a second plate having a fastening portion extending longitudinally inward relative to the first plate; and a thermal expansion member made of a thermally expandable material; wherein the fastening portion penetrates the first hole to fasten the first plate and the main body, and the thermal expansion member expands in volume upon thermal runaway of the battery module, and the thermal expansion member has a second hole through which the fastening portion penetrates, and the end plate is interposed between the outer surface of the fastening portion and the inner surface of the first hole. Claim 2 The end plate of claim 1, wherein the fastening portion is made of a material that melts during thermal runaway of the battery module. Claim 3 In claim 2, the fastening portion is an end plate made of synthetic resin and is a weld rivet welded after penetrating the first hole. Claim 4 delete Claim 5 In claim 1, the thermal expansion member is an end plate provided along the length of the first hole such that its outer surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening part. Claim 6 The end plate according to claim 1, wherein the first hole includes a groove portion having a larger inner diameter than the remaining portion in a portion of the longitudinal inner end, and the thermal expansion member is provided along the length of the groove portion such that its outer surface corresponds to the inner surface of the groove portion and its inner surface corresponds to the outer surface of the fastening portion. Claim 7 The end plate according to claim 1, wherein the first hole includes a groove portion having a larger inner diameter than the remaining portion in a portion of the longitudinal inner end, and the thermal expansion member comprises: an insertion portion provided along the length of the first hole such that its outer surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening portion; and an insertion interference portion provided along the length of the groove portion such that its outer surface corresponds to the inner surface of the groove portion and its inner surface corresponds to the outer surface of the fastening portion. Claim 8 An end plate according to claim 1, wherein a third hole is provided along the longitudinal direction and further comprises a flame-retardant plate interposed between the first plate and the second plate along the longitudinal direction, and the fastening portion sequentially penetrates the third hole and the first hole to fasten the first plate, the flame-retardant plate, and the main body portion. Claim 9 In claim 8, the fastening portion is an end plate made of a material that melts during thermal runaway of the battery module. Claim 10 In claim 9, the fastening portion is an end plate made of synthetic resin and is a weld rivet welded after sequentially penetrating the third hole and the first hole. Claim 11 In claim 9, the thermal expansion member comprises: an end plate interposed between the outer surface of the fastening portion and the inner surface of the third hole, the second hole through which the fastening portion passes. Claim 12 An end plate according to claim 11, wherein the third hole has an inner diameter larger than that of the first hole, and the thermal expansion member is provided along the length of the third hole such that its outer surface corresponds to the inner surface of the third hole and its inner surface corresponds to the outer surface of the fastening part. Claim 13 In claim 11, the thermal expansion member is an end plate interposed between the outer surface of the fastening portion and the inner surface of the first hole. Claim 14 An end plate according to claim 13, wherein the first hole and the third hole have the same inner diameter as each other, and the thermal expansion member is provided along the length of the first hole and the third hole such that its outer surface corresponds to the inner surface of the first hole and the third hole, and its inner surface corresponds to the outer surface of the fastening part. Claim 15 An end plate according to claim 13, wherein the third hole has an inner diameter larger than that of the first hole, and the thermal expansion member comprises: an insertion portion provided along the length of the first hole such that its outer surface corresponds to the inner surface of the first hole and its inner surface corresponds to the outer surface of the fastening portion; and an insertion interference portion provided along the length of the third hole such that its outer surface corresponds to the inner surface of the third hole and its inner surface corresponds to the outer surface of the fastening portion. Claim 16 In claim 8, the flame-retardant plate is an end plate made of an electrically insulating material. Claim 17 The end plate according to claim 1, wherein the thermal expansion member is a foam material made of a material selected from the group comprising soft urethane, hard urethane, hard polyurethane, and phosphorus-based flame retardant. Claim 18 A battery module comprising an end plate according to any one of claims 1 to 3 and claims 5 to 17. Claim 19 A battery pack comprising the battery module of claim 18. Claim 20 An automobile comprising the battery pack of claim 19.

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