Battery module with improved airtightness and heat resistance of the module case

Abstract

A battery module according to the present invention includes at least one battery cell, a module case including a case body having an internal space capable of accommodating the battery cell and an open end on an upper side, and a top plate covering the open upper side of the case body and coupled to an upper part of the case body, wherein the open end of the case body has an assembly guide protrusion protruding upward from a surface thereof, the top plate has an assembly guide hole on its periphery which is coupled to the assembly guide protrusion by an interference fit, and the entire periphery of the outer surface of the portion where the open end of the case body and the periphery of the top plate contact each other is welded.

Description

[Technical field]

[0001] The present invention relates to a battery module, and more particularly, to a battery module having improved airtightness and heat resistance so that flames and gases are not discharged to the outside for a predetermined period of time when the battery module ignites.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0159840 filed on November 18, 2021, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] Although a secondary battery may be used alone, it is generally configured in a form in which a plurality of secondary batteries are electrically connected to each other in series and / or parallel. In particular, a plurality of secondary batteries may be housed inside a module housing in a state in which they are electrically connected to each other to configure one battery module. The battery module may be used alone, or two or more may be electrically connected to each other in series and / or parallel to configure a higher level device such as a battery pack.

[0004] Meanwhile, when multiple battery modules are closely packed together, they may be vulnerable to fire. For example, when a battery cell of a battery module experiences thermal runaway, high-temperature gas or sparks may be emitted from the battery cell if the thermal runaway becomes severe. Here, the sparks refer to active material detached from an electrode inside the battery cell or molten aluminum particles. In some cases, flames may also be generated from the battery cell. If such gas or flames are indiscriminately discharged outside the battery module, they may cause thermal damage to the surrounding battery modules and the fire may spread rapidly.

[0005] However, the conventional battery module has a problem that, when a fire breaks out inside the battery module, gas and flames are discharged in many directions due to insufficient airtight structure, and the fire is likely to spread to other battery modules. For example, as shown in FIG. 1, a battery module according to the conventional technology includes a module housing composed of a U-frame 1 and a top plate 2, and a front cover 3 and a rear cover 4 covering the front and rear of the module housing, respectively. Here, the U-frame is a frame in which a bottom plate covering the lower part of a battery cell and two side plates covering both sides of the battery cell are integrally manufactured, and the top, front, and rear are open. As shown in the enlarged view of FIG. 1, such a module housing is configured to have airtightness by digging a groove, fitting and fixing the U-frame and the top plate, and then welding W at the contact points between the periphery of the U-frame and the top plate.

[0006] However, since the grooved portion 6 of the U-frame and the top plate is not welded due to the assembly structure, it is difficult to ensure sufficient airtightness. For example, even if the groove portion 6 is closed using a sealing material such as rubber or sealant, when high-temperature gas or flame occurs, the sealing material melts and disappears, so that the gas or flame may be discharged to the outside through the sealing material. In addition, since the front cover and the rear cover of the conventional battery module are made from plastic injection molding, it is difficult to ensure an airtight structure by welding at the portion where the module housing and the front cover or the rear cover are assembled. In addition, since the module housing of the conventional battery module is made from a single metal of aluminum system (melting point about 660°C), there is also a problem that when a fire occurs, thermal distortion occurs in the U-frame or the top plate at a certain temperature or higher, and airtightness cannot be maintained. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been devised to solve the above problems, and an object of the present invention is to provide a battery module with enhanced airtightness so that gas and flames are not discharged to the outside for a predetermined period of time when a fire occurs inside the battery module.

[0008] The technical problems that the present invention aims to solve are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0009] According to the present invention, it is possible to provide a battery module including a module case including at least one battery cell, a case body having an internal space capable of accommodating the battery cell and an open end on an upper side, and a top plate covering the open upper side of the case body and coupled to an upper part of the case body, wherein the open end of the case body has an assembly guide protrusion protruding upward from its surface, and the top plate has an assembly guide hole on its peripheral portion which is coupled to the assembly guide protrusion by an interference fit, and the entire circumference of the outer surface of the portion where the open end of the case body and the peripheral portion of the top plate contact each other is welded.

[0010] The case body may be in the form of a sealed box except for an open upper side.

[0011] The case body may include a bottom plate forming a bottom surface and wall plates forming front, rear, left and right walls, and the open end of the case body may be configured at the upper end of the wall plates.

[0012] The open end of the case body may be provided in the shape of a flange, protruding horizontally outward beyond other portions of the wall plate.

[0013] The module case may be made of clad metal made by bonding together different metals.

[0014] The case body may include an outside portion forming an outer surface of the case body and made of a first metal, and an inside portion forming an inner surface of the case body and made of a second metal having a higher melting point than the first metal, and the open end of the case body may be configured at an upper peripheral portion of the outside portion.

[0015] The top plate may include a first cover portion and a second cover portion forming a double layer, the first cover portion forming an outer surface of the top plate and being made of the first metal, and the second cover portion forming an inner surface of the top plate and being made of the second metal.

[0016] The first cover portion may be configured to be placed on an upper peripheral edge portion of the outside portion, and the second cover portion may be configured to be placed on an upper peripheral edge portion of the inside portion.

[0017] The assembly guide hole may be provided on a peripheral edge of the first cover portion.

[0018] The first cover portion and the second cover portion may have the same area, and the assembly guide hole may be provided only on the peripheral portion of the second cover portion among the peripheral portion of the first cover portion and the peripheral portion of the second cover portion.

[0019] According to another aspect of the present invention, a battery pack can be provided that includes the battery module described above. Effect of the Invention

[0020] According to one aspect of the present invention, a battery module having enhanced airtightness can be provided so that gas or flames are not discharged to the outside for a predetermined period of time when a fire occurs inside the battery module.

[0021] According to the present invention, a top plate is stably placed on the open end of the case body that constitutes the module case, and the entire periphery of the point where the open end of the case body and the peripheral edge of the top plate contact each other is welded, so that airtightness can be ensured even if a fire breaks out inside the battery module.

[0022] In addition, according to another aspect of the present invention, the module case is made of clad metal, and a metal that is relatively more heat resistant than aluminum forms the inner surface of the module case, making it possible to provide a battery module having higher mechanical rigidity and heat resistance than conventional battery modules.

[0023] The effects of the present invention are not limited to those described above, and other effects not mentioned herein will be clearly understood by those skilled in the art from the description of the claims. [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic diagram of a battery module according to the prior art; [Diagram 2] 1 is a diagram illustrating a battery module according to an embodiment of the present invention; [Diagram 3] FIG. 3 is a partially exploded perspective view of the battery module of FIG. 2. [Figure 4] 11A and 11B are views showing an assembly guide protrusion of a case body and an assembly guide hole of a top plate according to an embodiment of the present invention. [Diagram 5] FIG. 2 is an enlarged view of a portion of a module case according to an embodiment of the present invention, showing an assembly and welding structure of a case body and a top plate. [Figure 6] FIG. 2 is a perspective view showing a case body according to an embodiment of the present invention. [Figure 7] FIG. 2 is a bottom perspective view of a top plate according to an embodiment of the present invention; [Figure 8] 1 is a partial cross-sectional view of a battery module according to an embodiment of the present invention; [Figure 9]4 is a partial cross-sectional view of a battery module according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as being in accordance with the meaning and concept of the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of the term in order to best describe the invention. Therefore, it should be understood that the embodiment described in this specification and the configuration shown in the drawings are merely the most preferred embodiment of the present invention, and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0026] FIG. 2 is a schematic diagram of a battery module according to one embodiment of the present invention, FIG. 3 is a partially exploded oblique view of the battery module of FIG. 2, FIG. 4 is a diagram showing an assembly guide protrusion of a case body and an assembly guide hole of a top plate according to one embodiment of the present invention, and FIG. 5 is an enlarged view of a portion of a module case according to one embodiment of the present invention, showing the assembly and welding structure between the case body and the top plate.

[0027] 2 to 5, a battery module 10 according to an embodiment of the present invention includes a plurality of battery cells 100, a module case 200 including a case body 210 having an internal space capable of accommodating the plurality of battery cells 100 and an open end 212a on the upper side, and a top plate 220 coupled to an upper portion of the case body 210 so that the internal space is sealed.

[0028] The battery cell 100 has a thin plate-shaped body and may be a pouch-type secondary battery.

[0029] The pouch-type secondary battery includes a pouch exterior material, an electrode assembly provided so as to be accommodated in the pouch exterior material, and an electrolyte. For example, the pouch exterior material may be composed of two pouches, and a recessed internal space may be formed in at least one of them. The electrode assembly may be accommodated in the internal space of such a pouch. The two pouches may be fused to each other around their circumferences to seal the internal space accommodating the electrode assembly. An electrode lead may be attached to the electrode assembly, and the electrode lead may be interposed between the fused parts of the pouch exterior material and exposed to the outside of the pouch exterior material to function as an electrode terminal of the pouch-type secondary battery. Such pouch-type secondary batteries may be stacked in the vertical direction and stacked in the horizontal direction as shown in FIG. 3, and may be collectively accommodated in the case body 210.

[0030] Needless to say, the battery cell 100 does not necessarily have to be composed of a pouch-type secondary battery. For example, unlike the present embodiment, the battery cell 100 may be composed of a cylindrical secondary battery or a prismatic secondary battery that uses a metal can as an exterior material. In other words, a wide variety of battery cells 100 that are publicly known at the time of filing the present invention can be adopted in the battery module 10 of the present invention.

[0031] The module case 200 is a structure for housing, supporting, and protecting the battery cells 100, and is composed of a case body 210 and a top plate 220.

[0032] As will be described in more detail later, the battery module 10 of the present invention has a structure in which all sides of the case body 210 except for the top are closed, and the top of such case body 210 is covered with a top plate 220. However, by completely welding the contact points between the open end 212a of the case body 210 and the top plate 220 along the circumferential direction, it is configured so that airtightness is unlikely to be destroyed even when the battery cell 100 ignites.

[0033] For reference, the positive electrode terminal 310 and the negative electrode terminal 320 of the battery module 10 may be configured to pass through one wall of the case body 210 as shown in Fig. 3. In addition, in order to ensure insulation between the positive electrode terminal 310 and the negative electrode terminal 320 and the case body 210, the portions of the positive electrode terminal 310 and the negative electrode terminal 320 that pass through the case body 210 may be insulated with a material having excellent fire resistance and insulation properties, such as mica.

[0034] Although not shown for convenience of drawing, a gas vent port (not shown) may be configured on at least one side of the case body 210 in order to intentionally exhaust gas from the module case 200 to a specific path when the battery cell 100 ignites. For example, the gas vent port may be configured to have a mechanism for applying a rupture membrane to a hole, and to be normally closed and to be opened by breaking the rupture membrane when the internal pressure of the module case 200 rises to a predetermined pressure or higher. Note that a gas pipe (not shown) may be connected to the gas vent port outside the battery module 10, so that when an event occurs, high-temperature gas moves to a specific path along the gas pipe.

[0035] The assembly and welding structure of the case body 210 and the top plate 220, which are the main components of the module case 200, will be described in detail below.

[0036] The case body 210 (see FIG. 6) includes a bottom plate 211 forming a bottom surface supporting a lower portion of the stack of battery cells 100, and a wall plate 212 forming walls covering the front, rear, left, and right of the stack of battery cells 100, and may be provided in a box shape with an open upper side and a sealed portion except for the upper side. Therefore, an open end 212a of the case body 210 is disposed on the upper peripheral edge of the wall plate 212.

[0037] 3, the open end 212a of the case body 210 is provided in a flange shape that protrudes horizontally outward from other parts of the wall plate 212. That is, the open end 212a of the case body 210 is configured in a shape that protrudes over the entire circumference of the upper end of the wall plate 212. As a result, the case body 210 has the open end 212a with a sufficiently wide contact interface with the top plate 220, and there is a high degree of freedom in designing the size and position of the assembly guide protrusions 212b described later.

[0038] The open end 212a of the case body 210 has an assembly guide protrusion 212b protruding upward from its surface. The assembly guide protrusion 212b can be used as a means for placing the top plate 220 so as to be fixed on the open end 212a of the case body 210 and preventing loose movement during subsequent welding.

[0039] As shown in FIG. 3, the assembly guide protrusions 212b may be provided in multiple numbers, and the multiple assembly guide protrusions 212b may be positioned at predetermined intervals on the left long side line and the right long side line of the open end 212a of the case body 210 and may be formed in a cylindrical shape.

[0040] Meanwhile, the scope of the present invention is not limited to the position and shape of the assembly guide protrusions 212b. The assembly guide protrusions 212b may be configured differently from the present embodiment. For example, the assembly guide protrusions 212b may be positioned at predetermined intervals all around the open end 212a of the case body 210, including the long side line and the short side line, and may be formed in various shapes such as a polygonal column shape, a hemisphere shape, etc.

[0041] Such assembly guide projections 212b can prevent incorrect assembly of the case body 210 and the top plate 220, and can also function as stoppers that prevent the top plate 220 from moving up, down, left, or right.

[0042] The top plate 220 is a cover structure for sealing the internal space of the case body 210, and is installed so as to be accurately aligned with the open end 212a of the case body 210 based on the assembly guide protrusions 212b.

[0043] The top plate 220 has an assembly guide hole 220a on its periphery. When the top plate 220 is assembled to the case body 210, the assembly guide hole 220a and the assembly guide protrusion 212b are configured to be coupled to each other by a vertical interference fit, so that the periphery of the top plate 220 is accurately aligned with the open end 212a of the case body 210.

[0044] 3, the top plate 220 is provided with assembly guide holes 220a corresponding to the number of assembly guide protrusions 212b, and the assembly guide holes 220a are arranged at positions vertically corresponding one-to-one to the assembly guide protrusions 212b on the periphery of the top plate 220. Therefore, as shown in FIG. 4, when the assembly guide holes 220a are aligned with the assembly guide protrusions 212b as a reference and the top plate 220 is placed on the open end 212a of the case body 210, the case body 210 and the top plate 220 can be accurately aligned.

[0045] Furthermore, since each assembly guide protrusion 212b and each assembly guide hole 220a are connected to each other by a tight fit in the vertical direction, no misalignment occurs between the case body 210 and the top plate 220 during the subsequent welding work.

[0046] As described above, with the top plate 220 accurately placed on the open end 212a of the case body 210, the entire periphery of the outer surface of the contact portion between the open end 212a of the case body 210 and the peripheral edge of the top plate 220 is welded without any gaps as shown in Fig. 5. Therefore, the module case 200 of the battery module 10 according to the present invention (see Fig. 2) has a weld bead WB line that continues uninterruptedly along the entire periphery.

[0047] Therefore, even in a situation where the battery module 10 catches fire, the airtight structure between the case body 210 and the top plate 220 is not easily broken, and high-temperature gas and flames are not discharged to the outside from between the open end 212a of the case body 210 and the peripheral portion of the top plate 220.

[0048] FIG. 6 is a perspective view showing a case body according to one embodiment of the present invention, FIG. 7 is a perspective view looking up from below at a top plate according to one embodiment of the present invention, and FIG. 8 is a partial cross-sectional view of a battery module according to one embodiment of the present invention.

[0049] Meanwhile, the module case 200 according to an embodiment of the present invention may be constructed with different inner and outer materials from a lightweight clad metal made by bonding different metals together so as to have high heat resistance while being lightweight.

[0050] Specifically, referring to Figures 6 and 8, case body 210 includes an outside portion 213 which forms the outer surface of case body 210 and is made of a first metal, and an inside portion 214 which forms the inner surface of case body 210 and is made of a second metal having a higher melting point than the first metal.

[0051] In this embodiment, the first metal may be lightweight aluminum (Al), and the second metal may be stainless steel. The melting point of aluminum is about 660°C, and the melting point of stainless steel is about 2750°C. That is, in the case body 210 according to this embodiment, the outside part 213 is made of aluminum, and the inside part 214 is made of stainless steel, which has higher heat resistance than the aluminum. Needless to say, at least one of the first metal and the second metal may be replaced with a highly heat-resistant metal different from that of this embodiment.

[0052] As described above, the case body 210 is made of clad metal, and the bottom plate 211 and the wall plate 212 have a double-layer structure as shown in Fig. 6. Moreover, the case body 210 of this embodiment has a step between the upper peripheral edge of the outside part 213 that forms the wall plate 212 and the upper peripheral edge of the inside part 214. In other words, the upper end of the outside part 213 is set higher than the upper end of the inside part 214, and such upper peripheral edge of the outside part 213 is used as the open end 212a of the case body 210.

[0053] As shown in FIG. 7, the top plate 220 includes a first cover portion 221 and a second cover portion 223 forming a double layer.

[0054] The first cover part 221 forms an outer surface of the top plate 220 and is made of the first metal. The second cover part 223 forms an inner surface of the top plate 220 and is made of the second metal. That is, in the top plate 220 according to the present embodiment, the first cover part 221 is made of aluminum and the second cover part 223 is made of stainless steel.

[0055] In this embodiment, as shown in Figures 7 and 8, the assembly guide hole 220a is provided on the peripheral portion of the first cover portion 221, the peripheral portion of the first cover portion 221 is placed on the upper peripheral portion of the outside portion 213 of the case body 210, and the second cover portion 223 is configured so that its peripheral portion is placed on the upper peripheral portion of the inside portion 214 of the case body 210.

[0056] According to the configuration of the module case 200, the inner walls of the module case 200 that enclose the internal space of the module case 200 are all made of highly heat-resistant stainless steel. Therefore, when the inside of the battery module 10 catches fire, the module case 200 can withstand high temperatures and does not warp, so that airtightness can be maintained.

[0057] As described above, according to one embodiment of the present invention, the top plate 220 can be stably placed on the open end 212a of the case body 210, and the entire periphery of the contact point between the open end 212a of the case body 210 and the peripheral portion of the top plate 220 can be welded. Therefore, when a fire breaks out inside the battery module 10, gas and flames are not indiscriminately discharged to the outside of the module case 200.

[0058] In addition, the module case 200 is made of clad metal, and a metal that is relatively more heat resistant than aluminum forms the inner surface of the module case 200, making it possible to provide a battery module 10 that has higher mechanical rigidity and heat resistance than conventional battery modules.

[0059] Next, a battery module 10 according to another embodiment of the present invention will be briefly described with reference to Fig. 9. The same component numbers as those in the above-described embodiment indicate the same components, and redundant descriptions of the same components will be omitted, with the focus being on differences from the above-described embodiment.

[0060] The battery module 10 according to this embodiment of the present invention is different from the above-described embodiment in the assembly structure between the assembly guide protrusions 212b of the case body 210 and the assembly guide holes 220a of the top plate 220.

[0061] 9, the outside part 213 and the inside part 214 of the wall plate 212 according to another embodiment of the present invention are configured to have the same height at the top. In addition, in the case of the top plate 220, the first cover part 221 and the second cover part 223 are configured to have the same area, but the assembly guide hole 220a is configured to be provided only on the periphery of the second cover part 223 among the periphery of the first cover part 221 and the periphery of the second cover part 223. That is, in the other embodiment of the present invention, the upper part of the assembly guide hole 220a is closed. Therefore, unlike the above embodiment, the assembly guide protrusion 212b of the open end 212a of the case body 210 is not exposed above the assembly guide hole 220a.

[0062] For example, if there is a small gap between the assembly guide protrusion 212b and the assembly guide hole 220a due to an assembly tolerance between them, there may be a possibility that gas may leak into the gap in the above-mentioned embodiment. However, in the case of the other embodiment of the present invention, since the upper part of the assembly guide hole 220a is closed, there is an advantage that even if there is a gap between the assembly guide protrusion 212b and the assembly guide hole 220a as described above, there is no possibility that gas may leak out to the outside.

[0063] Meanwhile, a battery pack (not shown) according to the present invention includes one or more of the above-mentioned battery modules. In addition to the battery modules, the battery pack may further include a pack case (not shown) for accommodating the battery modules, and various devices (not shown) for controlling charging and discharging of the battery modules, such as a battery management system (BMS), a current sensor, a fuse, etc.

[0064] Meanwhile, in this specification, directional terms such as up, down, left, right, front, and back are used, but these terms are used merely for ease of explanation, and it will be obvious to those skilled in the art of the present invention that they may vary depending on the position of the object in question, the position of the observer, etc.

[0065] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the scope of the technical concept of the present invention and the scope of the claims. [Explanation of symbols]

[0066] 10 Battery Module 100 Battery Cells 200 module case 210 Case body 211 Bottom Plate 212 Wall Plate 212a open end 212b Guide protrusion 213 Outside Division 214 Inside 220 Top Plate 220a Guide hole 221 First Lid Body 223 Second cover body 310 Positive terminal 320 Negative terminal

Claims

1. at least one battery cell; a module case including a case body having an internal space capable of accommodating the battery cells and an open end at an upper side, and a top plate covering an open upper side of the case body and coupled to an upper portion of the case body; Including, the open end of the case body has an assembly guide protrusion protruding upward from its surface, and the top plate has an assembly guide hole on its periphery that is coupled with the assembly guide protrusion by an interference fit; a battery module, the periphery of an outer surface of a portion where the open end of the case body and the peripheral edge portion of the top plate contact each other being welded entirely around the periphery thereof.

2. The battery module according to claim 1 , wherein the case body is provided in a box shape that is sealed except for an open upper side.

3. The case body includes a bottom plate forming a bottom surface and wall plates forming front, rear, left and right wall surfaces, The battery module according to claim 1 , wherein the open end of the case body is an upper end of the wall plate.

4. The battery module according to claim 3 , wherein the open end of the case body is provided in the form of a flange that protrudes horizontally outward beyond other portions of the wall plate.

5. The battery module according to claim 1 , wherein the module case is made of a clad metal made by bonding different kinds of metals together.

6. The case body includes: an outside portion that forms an outer surface of the case body and is made of a first metal; and an inside portion that forms an inner surface of the case body and is made of a second metal having a melting point higher than that of the first metal, The battery module according to claim 5 , wherein the open end of the case body is an upper peripheral edge portion of the outside portion.

7. The top plate includes a first cover portion and a second cover portion forming a double layer, 7. The battery module according to claim 6, wherein the first cover portion forms an outer surface of the top plate and is made of the first metal, and the second cover portion forms an inner surface of the top plate and is made of the second metal.

8. The battery module according to claim 7 , wherein the first cover portion is placed on an upper peripheral edge portion of the outside portion, and the second cover portion is placed on an upper peripheral edge portion of the inside portion.

9. The battery module according to claim 7 , wherein the assembly guide hole is disposed on a periphery of the first cover portion.

10. The first cover portion and the second cover portion are provided to have the same area, The battery module according to claim 7 , wherein the assembly guide hole is provided only on the periphery of the second cover part among the periphery of the first cover part and the periphery of the second cover part.

11. A battery pack comprising the battery module according to any one of claims 1 to 10.

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