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 the contents disclosed in the documents of the Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an end plate that covers the front and rear of a battery module formed by integrating pouch-type battery cells, and the end plate is configured to delay or prevent heat propagation during thermal runaway.

Background Art

[0003] Rechargeable batteries, which are highly applicable to a wide range of products and have electrical characteristics such as high energy density, are commonly used not only in portable devices but also in electric vehicles or hybrid vehicles driven by an electric power source and power storage devices. These rechargeable batteries not only have the primary advantage of significantly reducing the use of fossil fuels but are also environmentally friendly in that they do not produce any by-products during energy use and are attracting attention as a new energy source for improving energy efficiency.

[0004] For small mobile devices, one or two or three battery cells are used per device. On the other hand, for medium- to large-sized devices such as automobiles, a large capacity with high output is required. Therefore, medium- to large-sized battery modules in which a large number of battery cells are electrically connected are used.

[0005] Medium- to large-sized battery modules are preferably manufactured with a small size and weight if possible, and thus, square batteries or pouch-type batteries that can be stacked with a high degree of integration and have a low weight-to-capacity ratio are mainly used as the battery cells of medium- to large-sized battery modules.

[0006] Figure 1 is a perspective view of a battery cell. Referring to this, a typical pouch-type battery cell 21 includes an electrode assembly formed by stacking multiple positive and negative electrodes with a separator membrane in between, a pouch 211 that houses and seals the electrode assembly, and electrode leads 212 that extend from the electrode assembly and protrude to the outside of the pouch 211. Multiple battery cells 21 can be stacked to form a battery cell stack, and the battery cell stack can form a single battery module.

[0007] Figures 2 and 3 are perspective and exploded perspective views showing the structure of the 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 houses the battery cell stack, and a pair of end plates 3 that cover the front and rear of the frame 1, respectively.

[0008] Figure 4 is an exploded perspective view showing the structure and connection relationship of the end plate and busbar frame. Referring to this, the electrode leads 212 that protrude forward and backward from the battery cell stack 2 pass through slits 41 provided in the busbar frame 1 and are welded to the busbar 42. The busbar 42 connects the electrode leads 212 to terminals 43 in parallel or in series with each other. The terminals 43 are exposed to the outside through an opening provided in the end plate 3, allowing the battery cell stack 2 to be connected to the outside.

[0009] Figure 5 is a front view of the end plate, Figure 6 is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided, and Figure 7 is an enlarged cross-sectional view showing the state of thermal runaway occurring in Figure 6. Referring to these drawings together with Figure 4, the end plate 3 may consist of 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, joined front to back. The first plate 31 is provided with a first hole 311, and the second plate 32 consists of a main body portion 321 and a fastening portion 322, and the fastening portion 322 fastens the first plate 31 and the main body portion 321 to each other by welding through the first hole 311. If thermal runaway occurs in the battery module (M), the second plate 32, which is made of synthetic resin material, may melt due to the heat, thereby opening the first hole 311 and creating a risk that thermal energy, gas, and flames will be discharged from inside the battery module (M) to the outside through the first hole 311.

[0010] Figure 22 is a perspective view showing a battery pack including battery modules. Referring to this, multiple battery modules (M) can be housed in a single frame to constitute a battery pack (P). In this case, the battery modules (M) are arranged adjacent to each other with their end plates 3, which expose the terminals 43, facing each other. Therefore, in the event of thermal runaway in a battery module (M), the heat energy, gas, and flames discharged through the first hole 311 can propagate to adjacent battery modules, thereby creating a risk of chain reaction ignition. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The present invention was conceived against the background of the prior art described above, and aims 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 to the end plate side.

[0012] Another technical problem of the present invention is to provide an end plate structure that does not significantly alter the structure of existing battery modules and can economically delay or prevent chain reactions between battery modules within a battery pack.

[0013] The technical problems of the present invention are not limited to the purposes mentioned above. Other purposes and advantages of the present invention not mentioned can be understood from the following description and will be more clearly understood from the embodiments of the present invention. Furthermore, it will be readily understood that the purposes and advantages of the present invention can be achieved by the means and combinations thereof described in the claims. [Means for solving the problem]

[0014] To solve the above problems, the present invention provides an end plate for covering the longitudinal end of a battery module, comprising: a first plate having a first hole penetrating through it in the longitudinal direction; a main body portion and a fastening portion extending outward in the longitudinal direction from the main body portion, and a second plate provided longitudinally inward compared to the first plate; and a thermal expansion member made of a thermally expandable material, wherein the fastening portion penetrates the first hole and fastens the first plate and the main body portion, and the thermal expansion member expands in volume when the battery module experiences thermal runaway.

[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 be welded after passing through the first hole, so that its longitudinal end expands radially outward, thereby fastening the first plate and the main body to each other.

[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 placed over it, thereby allowing the thermal expansion member to be interposed between the outer circumferential surface of the fastening portion and the inner circumferential surface of the first hole.

[0018] 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 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 can correspond to the inner diameter of the first 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 length of the first hole.

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

[0020] In the first modified example, the thermal expansion member may be provided along the length of the groove such 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 the 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 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, and the insertion interference portion may be provided along the length of the groove such 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.

[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 direction. The flame-retardant plate may be provided with a third hole penetrating in the length direction. The fastening portion can sequentially penetrate through the third hole and the first hole to fasten the first plate, the flame-retardant plate, and the main body portion.

[0023] The fastening portion can penetrate through the third hole in a state where the thermal expansion member is covered, whereby the thermal expansion member can be interposed between the outer peripheral surface of the fastening portion and the inner peripheral surface of the third hole.

[0024] In another embodiment of the present invention, the inner diameter of the third hole may be larger than that of the first hole. At this time, the thermal expansion member may be provided along the length of the third hole such 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. In other words, the outer diameter of the thermal expansion member can correspond to the inner diameter of 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 length of the third hole.

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

[0026] In a first modification, the first hole and the second hole may have the same inner diameter. At this time, the thermal expansion member may be provided along the lengths of the first hole and the third hole such 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 the second modification, the inner diameter of the third hole may be larger than that of the first hole. At this time, 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. The insertion interference portion may be provided along the length of the third hole such 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 having flame retardancy and electrical insulation.

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

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

Advantages of the Invention

[0031] The present invention provides a structure of an end plate that can prevent thermal energy, gas, and flame from being discharged to the end plate side by expanding the thermal expansion member and closing the first hole and the second hole even when the second plate melts during thermal runaway of the battery module.

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

[0033] Further, 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.

[0034] 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 melts due to thermal runaway, thereby suppressing further ignition due to short circuits.

[0035] In addition to the above, the present invention can achieve various other effects, which will be explained in each embodiment, or, in cases where such effects can be easily inferred by an ordinary person, such explanations will be omitted. [Brief explanation of the drawing]

[0036] [Figure 1] This is a perspective view of a battery cell. [Figure 2] This is a perspective view showing the structure of a battery module. [Figure 3] This is an exploded perspective view showing the structure of the battery module. [Figure 4] This is an exploded perspective view showing the structure and connection relationship of the end plate and busbar frame. [Figure 5] This is a front view of the end plate. [Figure 6] This is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided. [Figure 7] Figure 6 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 8] This is an exploded perspective view showing the structure of an end plate according to Embodiment 1 of the present invention. [Figure 9] This is an enlarged cross-sectional view showing the portion of the end plate according to Embodiment 1 of the present invention in which the first hole is provided. [Figure 10] Figure 9 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 11] This is an enlarged cross-sectional view showing the portion of the end plate in which the first hole is provided, according to a first modification of Embodiment 1 of the present invention. [Figure 12] Figure 11 is an enlarged cross-sectional view showing the state of thermal runaway that occurred. [Figure 13]This is an enlarged cross-sectional view showing the portion of the end plate in which the first hole is provided, according to a second modification of Embodiment 1 of the present invention. [Figure 14] Figure 13 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 15] This is an exploded perspective view showing the structure of an end plate according to Embodiment 2 of the present invention. [Figure 16] This is an enlarged cross-sectional view showing the portion of the end plate according to Embodiment 2 of the present invention in which the first hole is provided. [Figure 17] Figure 16 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 18] This is an enlarged cross-sectional view showing the portion of the end plate in which the first hole is provided, according to the first modification of Embodiment 2 of the present invention. [Figure 19] Figure 18 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 20] This is an enlarged cross-sectional view showing the portion of the end plate in which the first hole is provided, according to a second modification of Embodiment 2 of the present invention. [Figure 21] Figure 20 is an enlarged cross-sectional view showing the thermal runaway that occurred. [Figure 22] This is a perspective view showing a battery pack including the battery module. [Figure 23] This is a perspective view showing a car including a battery pack. [Modes for carrying out the invention]

[0037] The aforementioned objectives, features, and advantages will be described in detail below with reference to the accompanying drawings, so that a person with ordinary skill in the art to which the present invention pertains can easily implement the technical concept of the present invention. In describing the present invention, if a specific description of known technology according 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," "second," etc., are used to indicate various components, these components are not limited by these terms. These terms are simply used to distinguish one component from another, and unless otherwise specified, the first component may also be the second component.

[0039] In the entire specification, unless otherwise stated, each component may be singular or plural.

[0040] In the following, the placement of any configuration on the "upper (or lower)" or "above (or below)" of a component means not only that the configuration is placed in contact with the upper (or lower) surface of the component, but also that other configurations may be interposed between the component and any configuration placed on (or below) it.

[0041] Furthermore, where it is stated that one component is “linked,” “joined,” or “connected” to another component, it should be understood that the components may be directly linked or connected to one another, but may also be “interposed” between each component, or each component may be “linked,” “joined,” or “connected” through other components.

[0042] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as “composed of” or “including” in this application should not be interpreted as necessarily including all of the multiple components or steps described in the specification, but rather as including some of the components or steps, or including further components or steps.

[0043] Wherever "A and / or B" is written in the entire specification, it means A, B, or A and B unless otherwise specified, and wherever "C~D" is written, it means C or greater and D or less unless otherwise specified.

[0044] Figures 2 and 3 are perspective and exploded perspective views showing the structure of a battery module. Referring to these drawings, the present invention provides an end plate 3 that covers the longitudinal end of a battery module (M), comprising: a first plate having a first hole penetrating through it in the longitudinal direction; a main body portion and a fastening portion extending outward in the longitudinal direction from the main body portion, and a second plate provided longitudinally inward compared to the first plate; and a thermal expansion member made of a thermally expandable material, wherein the fastening portion penetrates the first hole and fastens the first plate and the main body portion, and the thermal expansion member expands in volume when the battery module experiences thermal runaway.

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

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

[0047] [Example 1] Figure 8 is an exploded perspective view showing the structure of an end plate according to Embodiment 1 of the present invention. Referring to this, the end plate 3 according to this 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 that penetrates through it in 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 outward in the longitudinal direction from the main body portion. The second plate 32 may be provided further inward in the longitudinal direction compared to the first plate 31.

[0050] The fastening portion 322 penetrates the first hole 311 and can 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 in the event of 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 second plate 32 may be made entirely of a synthetic resin material, including the main body portion 321 and the fastening portion 322, for insulation between the inside of the battery module and the first plate 31.

[0051] The fastening portion 322 may be a weld rivet that fastens the first plate 31 and the main body portion 321 together by welding with heat on the longitudinal outer side of the first plate 31 after passing through the first hole 311, so that its longitudinal outer end expands radially outward.

[0052] The thermal expansion member 33 may be made of a material that has thermal expansion properties. In this case, the thermal expansion member 33 may expand in volume 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 with the thermal expansion member 33 placed over it, thereby allowing the thermal expansion member 33 to be interposed between the outer circumferential surface of the fastening portion 322 and the inner circumferential surface of the first hole 311.

[0055] Figure 9 is an enlarged cross-sectional view showing the portion of the end plate according to Embodiment 1 of the present invention in which the first hole is provided. 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 can correspond to the inner diameter of the first hole 311, 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 first hole 311.

[0056] The end plate 3 according to this embodiment may include: a first plate 31 having a first hole 311 that penetrates in the longitudinal direction; a second plate 32 provided inward in the longitudinal direction compared to the first plate 31, including a main body portion 321 and a fastening portion 322 that extends outward in the longitudinal direction from the main body portion 321, and after penetrating the first hole 311, is welded so that its outer end in the longitudinal direction expands outward in the radial direction, fastening the first plate 31 and the main body portion 321 together; and a thermal expansion member 33 having a second hole 331 through which the fastening portion 322 penetrates, 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, the length of which corresponds to the length of the first hole 311, and interposed between the inner circumferential surface of the first hole and the outer circumferential surface of the fastening portion 322 along the length of the first hole 311.

[0057] Figure 10 is an enlarged cross-sectional view showing the thermal runaway that occurred in Figure 9. Referring to this, when the battery module experiences thermal runaway, the fastening portion 322 may melt, causing thermal energy, gas, and flames inside the battery module to be discharged to the outside and adjacent battery modules through the first hole 311, creating a risk of heat propagation and chain reaction ignition between modules. At this time, the thermal expansion member 33 can expand and 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 this embodiment is that the same effect as described above can be obtained simply by leaving the first hole 311 as is or slightly enlarging its inner diameter, placing the thermal expansion member 33 over the fastening portion 322, and then inserting the fastening portion 322 into the first hole 311.

[0059] Figure 11 is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided according to the first modification of Embodiment 1 of the present invention, and Figure 12 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in Figure 11. Referring to these drawings, the first hole 311 in the first and second modifications of this embodiment may include a groove 312 in a portion of its 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 provided along the length of the groove 312 such 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, 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 modified example, the thermal expansion member 33 can be inserted simply by further processing the groove 312 into the existing first plate 31 in which the first hole 311 is provided, and the length of the thermal expansion member 33 can be short, making it economical. Furthermore, according to the first modified example, there is a step at the boundary between the portion of the first hole 311 in which the groove 312 is provided and the rest of the hole, which limits the insertion depth of the thermal expansion member 33, providing advantages in manufacturing.

[0061] Figure 13 is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided according to a second modification of Embodiment 1 of the present invention, and Figure 14 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in Figure 13. Referring to these drawings, in the second modification, 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, and 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 modification, the insertion depth of the thermal expansion member 33 is limited, which offers manufacturing advantages, and because the thermal expansion member 33 extends 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 explanation of parts not specifically mentioned in this embodiment is the same as in Embodiment 1 above.

[0063] Figure 15 is an exploded perspective view showing the structure of an end plate according to Embodiment 2 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 longitudinal direction. The flame-retardant plate 34 may be provided with a third hole 341 that penetrates through in the longitudinal direction. The fastening portion 322 can fasten the first plate 31, the flame-retardant plate 34, and the main body portion 321 by sequentially passing through the third hole 341 and the first hole 311.

[0064] The fastening portion 322 can pass through the third hole 341 with the thermal expansion member 33 placed over it, thereby allowing the thermal expansion member 33 to be interposed between the outer circumferential surface of the fastening portion 322 and the inner circumferential 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. When the main body 321 melts during thermal runaway of the battery module, there is a risk of a short circuit occurring between the inside of the battery module and the first plate 31. By being made of a flame-retardant material, the flame-retardant plate 34 does not melt during thermal runaway, and by being 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 short circuits and subsequent ignition during thermal runaway of the battery module.

[0066] The thermal expansion member 33 may be made of a foam material selected from the group including soft urethane, light urethane, light polyurethane, and phosphorus-based flame retardants. However, the thermal expansion member 33 may be made of any material that expands in volume when the battery module experiences thermal runaway.

[0067] Figure 16 is an enlarged cross-sectional view showing the portion of the end plate according to Embodiment 2 of the present invention in which the first hole is provided. Referring to this, in this embodiment, the inner diameter of the third hole 341 may be larger than that of 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 can correspond to the inner diameter of the third hole 341, 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 third hole 341.

[0068] The end plate 3 according to this embodiment comprises: a first plate 31 having a first hole 311 that penetrates in the longitudinal direction; a flame-retardant plate 34 made of an electrically insulating material, provided inward in the longitudinal direction compared to the first plate 31, and provided with a third hole 341 that penetrates in the longitudinal direction; and a main body portion 321 provided inward in the longitudinal direction compared to the flame-retardant plate 34, and extending outward in the longitudinal direction from the main body portion 321, passing through the third hole and the first hole 311 before being welded, so that its outer end in the longitudinal direction is radially The second plate 32 includes a fastening portion 322 that extends outward and fastens the first plate 31, the flame-retardant plate 34, and the main body portion 321 together; and a thermal expansion member 33 which has 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, the length of which corresponds to the length of the third hole 341, and is interposed between the inner circumferential surface of the third hole and the outer circumferential surface of the fastening portion 322 along the length of the third hole 341.

[0069] Figure 17 is an enlarged cross-sectional view showing the thermal runaway that occurred in Figure 16. Referring to this, when the battery module experiences thermal runaway, the fastening portion 322 may melt, thereby releasing thermal energy, gases, and flames from within the battery module to the outside and adjacent battery modules through the third hole 341 and the first hole 311, creating a risk of heat propagation and chain reactions between modules. At this time, the thermal expansion member 33 can expand and close the third hole 341, thereby effectively preventing thermal energy, gases, and flames from inside the battery module from being released through the third hole 341 and the first hole 311. Even if a portion of the fastening portion 322 still remains in the first hole 311, the thermal expansion member 33 can completely close the third hole 341, so that the thermal expansion member 33 can maintain a closed state of the first hole 311 as well, even though it is only provided in the third hole 341.

[0070] The advantages of this embodiment are that the flame-retardant plate 34 maintains insulation even during thermal runaway, no further processing is required for the first hole 311, and 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] Figure 18 is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided according to the first modification of Embodiment 2 of the present invention, and Figure 19 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in Figure 18. Referring to these drawings, the thermal expansion member 33 according to the first and second modifications of this embodiment can also be interposed between the outer circumferential surface of the fastening portion 322 and the inner circumferential 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 such that its outer circumferential surface corresponds to the inner circumferential surfaces of the first hole 311 and 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 can correspond to the inner diameters of the first hole 311 and the third hole 341, 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 first hole 311 and the third hole 341. According to the first modified example, the inner diameters of both the first hole 311 and the third hole 341 are easy to punch out, and the third hole 341 and the first hole 311 can be reliably closed along their entire length.

[0073] Figure 20 is an enlarged cross-sectional view showing the portion of the end plate where the first hole is provided according to a second modification of Embodiment 2 of the present invention, and Figure 21 is an enlarged cross-sectional view showing the state in which thermal runaway occurs in Figure 20. Referring to these drawings, in the second modification, the inner diameter of the third hole 341 may be larger than that of 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, and 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 machine 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 have manufacturing advantages by limiting the insertion depth.

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

[0075] Figure 1 is a perspective view of a battery cell. Referring to this, a pouch-type battery cell 21 to be housed in a medium-to-large battery module may include an electrode assembly formed by stacking multiple positive and negative electrodes with a separator membrane in between, a pouch 211 that houses and seals the electrode assembly, and electrode leads 212 that extend from the electrode assembly and protrude to the outside of the pouch 211. Multiple battery cells 21 can be stacked to form a battery cell stack, and the battery cell stack can form a single battery module.

[0076] Figures 2 and 3 are perspective and exploded perspective views 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 can be housed in the frame 1, which is open on both sides in the longitudinal direction, with its electrode leads 212 protruding in the longitudinal direction. In this case, the electrode leads 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 can cover both sides of the exposed longitudinal direction of the busbar frame 1.

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

[0078] Figures 22 and 23 are perspective views showing a battery pack including battery modules and an automobile including the battery pack, respectively. Referring to these drawings, multiple battery modules (M) can be housed within a single frame to constitute a battery pack (P). Multiple battery modules (M) may be arranged facing each other in the longitudinal direction, as described above. The battery pack (P) can be mounted in an electric vehicle (V) to function as a power source. The structure and manufacturing methods of these battery packs and electric vehicles are well known to the ordinary engineer and will not be described in detail herein.

[0079] The embodiments described above should be understood to be illustrative and not limiting in all respects, and the scope of the present invention is indicated more by the claims described below than by the detailed description above. The meaning and scope of the claims described below, as well as any modifications and deformable forms conceived from their equivalent concepts, should be interpreted as being included within the scope of the present invention.

[0080] As described above, the present invention has been explained with reference to the illustrative drawings. However, the present invention is not limited by the embodiments and drawings disclosed herein, and it is natural that various modifications can be made by an ordinary person 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 and explained while embodiments of the present invention have been described above, it is natural that predictable effects from such configurations should also be acknowledged. [Explanation of symbols]

[0081] M Battery Module 1 frame 2. Battery cell stack 21 battery cells 211 Pouch 212 Electrode Leads 4 Busbar Frame 41 Slits 42 Bus Bar Terminal 43 3 End Plates 31 Plate 1 311 Hole 1 312 Groove 32 Second Plate 321 Main body 322 Fastening part 33 Thermal expansion member 331 Hole 2 332 Insertion part 333 Insertion interference section 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 the longitudinal end of a battery module, A first plate having a first hole that penetrates through it in the longitudinal direction; A second plate comprising a main body and a fastening portion extending outward in the longitudinal direction from the main body, and provided inward in the longitudinal direction compared to the first plate; and Includes a thermally expandable member made of a thermally expandable material; The fastening portion penetrates 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 according to claim 1.

3. The fastening portion is made of synthetic resin and is a welding rivet that penetrates the first hole and then welds into place. The end plate according to claim 2.

4. The aforementioned thermal expansion member is The fastening portion includes a second hole through which it passes, Interposed between the outer circumferential surface of the fastening portion and the inner circumferential 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 portion of its inner end in the longitudinal direction, which has a larger inner diameter than the rest of the hole. The thermal expansion member is provided along the length of the groove such 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 portion of its inner end in the longitudinal direction, which has a larger inner diameter than the rest of the hole. The aforementioned thermal expansion member is An insertion portion 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, It includes an insertion interference portion provided along the length of the groove such 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.

8. The present invention further includes a flame-retardant plate interposed between the first plate and the second plate along the length direction, which is provided with a third hole that penetrates in the length direction. 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. The end plate according to 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 made of synthetic resin and is a welding rivet that sequentially penetrates the third hole and the first hole before welding. The end plate according to claim 9.

11. The aforementioned thermal expansion member is The fastening portion includes a second hole through which it passes, Interposed between the outer circumferential surface of the fastening portion and the inner circumferential surface of the third hole, The end plate according to claim 9.

12. The third hole has a larger inner diameter than 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 according to claim 11.

13. The thermal expansion member is also interposed between the outer circumferential surface of the fastening portion and the inner circumferential surface of the first hole. The end plate according to 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 according to claim 13.

15. The third hole has a larger inner diameter than the first hole. The aforementioned thermal expansion member is An insertion portion 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, Includes 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 according to claim 13.

16. The aforementioned 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 from a material selected from the group including soft urethane, light urethane, light polyurethane, and phosphorus-based flame retardants. The end plate according to claim 1.

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

19. Includes the battery module described in claim 18, Battery pack.

20. Includes the battery pack described in claim 19, car.

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