Battery module and battery pack including said battery module

Abstract

A battery module according to the present invention includes at least one battery cell and a module case having an internal space and accommodating the battery cell, and the module case includes a weld bead portion where welding is performed at an edge line where one plate contacts another plate, and a pressure relief portion where welding is not performed and which has a gap.

Description

[Technical Field]

[0001] The present invention relates to a battery module and a battery pack including the battery module, and more particularly to a battery module having excellent safety against thermal events and a battery pack including the battery module.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0168016 filed on December 5, 2022, and Korean Patent Application No. 10-2023-0028738 filed on March 3, 2023, and the contents disclosed in the specifications and drawings of those applications are incorporated herein in their entirety. [Background technology]

[0003] As technological development and demand for various mobile devices, electric vehicles, energy storage systems (ESS), etc. increases dramatically, interest in and demand for secondary batteries as an energy source is rapidly increasing. Previously, nickel-cadmium batteries or nickel-metal hydride batteries were commonly used as secondary batteries, but this year, lithium secondary batteries are becoming more popular because they have almost no memory effect compared to nickel-based secondary batteries, can be charged and discharged freely, have a very low self-discharge rate, and have a high energy density.

[0004] Such lithium secondary batteries mainly use lithium-based oxides and carbon materials as the positive and negative electrode active materials, respectively, and include an electrode assembly in which a positive electrode plate and a negative electrode plate, each coated with the positive and negative electrode active materials, are arranged with a separator sandwiched therebetween, and an exterior material, i.e., a battery case, that hermetically houses the electrode assembly together with an electrolyte.

[0005] Generally, lithium secondary batteries are classified into can-type secondary batteries in which an electrode assembly is housed in a metal can and pouch-type secondary batteries in which an electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the exterior material.

[0006] The operating voltage of currently used lithium secondary batteries is approximately 2.5V to 4.5V per battery. Therefore, in the case of electric vehicles and power storage devices that require large capacity and high output, a battery module or battery pack is formed by connecting multiple lithium secondary batteries in series and / or parallel, and the battery module or battery pack is used as an energy source. In particular, to meet the output and capacity required for electric vehicles, the battery module or battery pack contains a large number of lithium secondary batteries.

[0007] Meanwhile, if a thermal event occurs in a battery module containing multiple battery cells and heat continues to accumulate inside the battery module, thermal runaway can rapidly spread between the battery cells, potentially causing extensive damage, such as an explosion of the battery module.

[0008] Therefore, for the safety of users, battery modules and battery packs must be designed to suppress or delay the spread of fire in the early stages of a thermal event.

[0009] As is widely known, the three elements of combustion are fuel, oxygen, and heat. Of these, the battery cell, which is the fuel, is almost impossible to remove in the event of a thermal event. Therefore, there is a growing need for a battery module that can effectively vent the heat source to the outside of the battery module in order to suppress or delay the spread of a thermal event. In particular, if the internal pressure of a battery module cannot be quickly released in the event of an internal fire, the risk of explosion increases, so a solution to this is needed. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above problems, and aims to provide a battery module that can effectively disperse and release internal pressure when a thermal event occurs inside the battery module.

[0011] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art upon carefully examining the following description of the invention. [Means for solving the problem]

[0012] A battery module according to one aspect of the present invention comprises: at least one battery cell; a module case having an internal space and accommodating the battery cells; The module case may include a weld bead portion where welding is performed at an edge line where one plate contacts another plate, and a pressure relief portion where welding is not performed and a gap is formed.

[0013] The pressure release portion may be configured at an upper end of the module case covering an upper portion of the battery cell, and may be provided in plurality at predetermined intervals along a longitudinal direction of the module case.

[0014] The module case may include a case body that surrounds the upper, lower, left, and right sides of the interior space, and end covers that cover the front and rear sides of the interior space and are interconnected with the case body.

[0015] The case body may include a U-shaped frame integrally formed with an upper plate covering the upper surface of the internal space, a lower plate covering the lower surface of the internal space, and a pair of side plates covering the left and right surfaces of the internal space.

[0016] The module case may be configured such that both edge lines along the longitudinal direction of the upper plate and edge lines at the upper ends of the pair of side plates along the longitudinal direction are welded together, excluding the pressure relief portion.

[0017] In the pressure release portion, the upper plate may have a rib insertion groove recessed in a direction intersecting with the side plate, and the side plate may have an assembly guide rib inserted perpendicularly into the rib insertion groove.

[0018] The rib insertion groove and the assembly guide rib may be provided to be form-fitted.

[0019] The upper plate may further include a double groove portion recessed toward the center of the upper plate in the rib insertion groove, and the module case may include an upper hole surrounded by the double groove portion and the assembly guide rib.

[0020] The side plate may have an upper end surface that contacts a lower portion of the edge region of the upper plate, and the pressure relief portion may have a gap expansion portion that is recessed so as not to contact the lower portion of the edge region of the upper plate.

[0021] The module case may have at least one gas vent hole at a bottom that supports a lower portion of the battery cell.

[0022] The battery cell may be a pouch-type battery cell, and the gas vent hole may be provided vertically below a cell terrace on which an electrode lead is provided in the pouch-type battery cell.

[0023] According to another aspect of the present invention, a battery pack including the battery module described above may be provided. [Effects of the Invention]

[0024] According to one aspect of the present invention, it is possible to provide a battery module that can effectively dissipate and relieve internal pressure when a thermal event occurs inside the battery module.

[0025] In addition, the present invention has various other effects, which will be described in each embodiment, or the description of effects that can be easily inferred by a person skilled in the art will be omitted. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic perspective view of a battery module according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic exploded perspective view of the battery module of FIG. 1. [Figure 3] FIG. 2 is a side view of the battery module of FIG. 1. [Figure 4] 1 is a perspective view showing an assembly guide rib and a rib insertion groove of a module case according to an embodiment of the present invention; [Figure 5] 5 is a view of the assembly guide rib and the rib insertion groove of FIG. 4 as seen from another angle. [Figure 6] 1 is a plan view showing a portion of an upper surface of a battery module according to an embodiment of the present invention; [Figure 7] FIG. 4 is an enlarged view of region A in FIG. [Figure 8] 2 is a view showing a bottom surface of a battery module according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0027] 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 construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts corresponding to the technical concept of the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of terms in order to best explain the invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical concept of the present invention, and therefore, various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0028] In the drawings, the size of each component or specific parts of the component may be exaggerated, omitted, or illustrated schematically for convenience and clarity of description. Therefore, the size of each component may not completely reflect the actual size. If a detailed description of well-known functions or configurations related to the present invention is deemed to unnecessarily obscure the gist of the present invention, such description will be omitted.

[0029] FIG. 1 is a schematic perspective view of a battery module according to one embodiment of the present invention, FIG. 2 is a schematic exploded perspective view of the battery module of FIG. 1, and FIG. 3 is a side view of the battery module of FIG.

[0030] Referring to these drawings, a battery module 10 according to an embodiment of the present invention includes at least one battery cell 110 and a module case 200 having an internal space for accommodating the battery cell 110 .

[0031] As will be described in more detail below, the module case 200 according to the present invention includes weld bead portions W1 and W2 formed by welding at an edge line where one plate meets another plate, and a pressure relief portion PR where no welding is performed and a gap is formed. Such a module case 200 has high bonding strength between the plates, so it is less likely to deform even when the battery cells 110 are swelling, for example, and has the effect of effectively dispersing and relieving internal pressure of the module case 200 in the event of a thermal event occurring in the battery module 10.

[0032] 1, a plurality of pressure relief parts PR may be provided at predetermined intervals along the longitudinal direction (Y direction) of the module case 200 at the upper end of the module case 200 that covers the upper part of the battery cell 110. When the internal pressure of such a module case 200 increases, gaps are formed between the plates of each pressure relief part PR, allowing gas to leak, and the internal pressure may be dispersed and relieved to multiple locations.

[0033] The main configuration of the battery module 10 according to the present invention will be described in detail below.

[0034] First, the battery cell 110 included in the battery module 10 may be a pouch-type secondary battery having a thin plate-shaped body.

[0035] The pouch-type secondary battery includes a pouch exterior, an electrode assembly accommodated in the pouch exterior, and an electrolyte. For example, the pouch exterior may be composed of two pouches, at least one of which may have a recessed internal space. The electrode assembly may be accommodated in the internal space of the pouch. The peripheral edges of the two pouches may be welded together to seal the internal space accommodating the electrode assembly. An electrode lead 111 may be attached to the electrode assembly. The electrode lead 111 may be interposed between the welded portions of the pouch exterior and exposed to the outside of the pouch exterior, thereby functioning as an electrode terminal of the pouch-type secondary battery. Here, the welded portion of the pouch exterior where the electrode lead 111 is located at the peripheral edge of the pouch exterior is referred to as a cell terrace.

[0036] Such pouch-type secondary batteries form a cell stack 100 in which cells are set upright and stacked left and right as shown in FIG. 2, and can be housed collectively in a module case 200.

[0037] A bus bar frame assembly 120 may be used to electrically connect the pouch-type secondary batteries.

[0038] The bus bar frame assembly 120 is typically composed of a bus bar frame 121, which is a plastic injection molding, and a bus bar 123, which is provided in the form of a rod made of an electrically conductive metal such as copper, aluminum, or nickel, and may be disposed in front of and / or behind the cell stack 100.

[0039] The bus bar 123 may be configured to be in direct contact with the electrode lead 111 of the pouch-type secondary battery. In particular, the bus bar 123 may be configured to maintain contact with the electrode lead 111 by welding or the like.

[0040] For example, the positive electrode leads of N (N is a natural number) pouch-type battery cells 110 and the negative electrode leads of the other N pouch-type battery cells 110 may be welded to the same bus bar 123, thereby connecting the pouch-type battery cells 110 in series and / or in parallel. The bus bar frame 121 may be provided as a substantially plate-like body having lead slits on one surface to which the bus bar 123 can be fixed and through which the electrode leads 111 are taken out.

[0041] Meanwhile, the battery cells 110 constituting the battery module 10 according to the present invention do not necessarily have to be pouch-type secondary batteries. A pouch-type secondary battery is merely one example of a battery cell 110 applicable to the battery module 10 according to the present invention. In other words, any type of secondary battery publicly known at the time of filing of the present invention may be the battery cell 110 constituting the battery module 10 according to the present invention.

[0042] The main part of the module case 200 may be made of a metal material having high mechanical rigidity so as to protect the battery cells 110 and other internal components from external impacts.

[0043] 1 and 2, a module case 200 according to an embodiment of the present invention may include a case body 210 that is arranged to surround the top, bottom, left, and right sides of an internal space in which battery cells 110 are accommodated, and end covers 220 and 230 that are arranged to cover the front and rear sides of the internal space and are connected to the case body 210.

[0044] The case body 210 may be configured in a substantially rectangular tubular shape with both ends open along the longitudinal direction so as to cover the top, bottom, and both side surfaces of the cell stack 100 except for the front and rear of the cell stack 100 (the direction in which the electrode leads 111 of the pouch-type battery cells 110 are located). The end covers 220 and 230 may be configured to cover the open portions of the case body 210. The inner surfaces of the end covers 220 and 230 may be insulated so that the bus bar frame assembly 120 is not exposed to the outside except for portions of the bus bars 123 that can function as electrode terminals of the battery module 10.

[0045] Hereinafter, in the case main body 210, the portion covering the upper surface of the internal space of the module case 200 (or the upper surface of the cell stack 100) is defined as an upper plate 211, the portion covering the lower surface of the internal space (or the lower surface of the cell stack 100) is defined as a lower plate 213, and the portions covering the left and right surfaces of the internal space (or both side surfaces of the cell stack 100) are defined as a pair of side plates 214, 215.

[0046] The case body 210 according to an embodiment of the present invention may be composed of the upper plate 211 and a U-shaped frame 212. Here, the U-shaped frame 212 refers to a component in which the lower plate 213 and the pair of side plates 214 and 215 are integrated together.

[0047] Specifically, the case body 210 may be provided in a form in which an upper plate 211 and a U-shaped frame 212 shown in Fig. 2 are joined by welding as shown in Fig. 1. For example, the cell stack 100 may be disposed inside the U-shaped frame 212, and the upper plate 211 may be joined to the upper end of the U-shaped frame 212 by welding. In addition, the end covers 220 and 230 may also be joined to the case body 210 by welding so as to be fixed to each other.

[0048] The case body 210, which is provided by housing the cell stack 100 in a U-shaped frame 212 and welding the upper plate 211 to the upper end of the U-shaped frame 212, facilitates housing the cell stack 100 compared to inserting the cell stack 100 into a case that is originally provided in a rectangular tubular shape. Furthermore, when the upper plate 211 and the U-shaped frame 212 are welded as shown in FIG. 1 while the cell stack 100 is being pressed by a pair of side plates 214 and 215, the gap between the pair of side plates 214 and 215 is maintained constant, and pressure continues to act on the cell stack 100. This has the effect of suppressing or mitigating swelling of the battery cells 110 that may occur during charging and discharging.

[0049] As described above, the module case 200 according to this embodiment is formed by welding the U-shaped frame 212 and the upper plate 211, or the case body 210 and the end covers 220 and 230. Therefore, the module case has weld bead portions W1 and W2, as shown in FIGS.

[0050] The module case 200 according to the present invention has at least one pressure relief portion PR at an edge line (along the longitudinal direction) of the top surface. In the module case 200, the edge line of the top surface is not entirely welded. That is, the module case 200 has a weld bead portion W1 on its top surface and a pressure relief portion PR that is an unwelded section.

[0051] The pressure relief portion PR may be configured to allow air to flow into and out of the module case 200 .

[0052] For example, the upper end of the U-shaped frame 212, in other words, the edge lines of the upper ends of the pair of side plates 214, 215, may be welded to both edge lines of the upper plate 211, but welding may be omitted in certain sections, thereby providing a weld bead portion W1 and an unwelded section at both edges of the upper surface of the module case 200. The pressure relief portion PR is provided in the unwelded section and has a gap. Here, the gap may refer to a portion or space that opens up between the side plates 214, 215 and the upper plate 211 due to internal pressure.

[0053] Therefore, when a thermal event occurs in the battery module, the gas escapes to the outside through the gaps in the pressure release portion PR, thereby preventing a sudden increase in the internal pressure of the battery module 10.

[0054] Furthermore, since a plurality of pressure relief portions PR are formed at predetermined intervals along both edge lines of the upper end surface of module case 200, gas can escape from a plurality of pressure relief portions PR. Therefore, the pressure due to the gas can be dispersed to a plurality of pressure relief portions PR without concentrating on any one pressure relief portion PR.

[0055] 1, 2, and 4 to 6, the module case 200 includes an assembly guide rib 216 and a rib insertion groove 211a.

[0056] Specifically, in the pressure relief section PR, the upper plate 211 has a rib insertion groove 211a recessed in a direction intersecting with the side plates 214, 215, and the side plates 214, 215 have an assembly guide rib 216 that protrudes higher than the upper end surfaces 214a of the side plates 214, 215 and is inserted perpendicularly into the rib insertion groove 211a.

[0057] The U-shaped frame 212 and the upper plate 211 are first assembled before being joined by welding. To improve welding quality, the upper plate 211 must be accurately mounted on the upper end of the U-shaped frame 212, and it is important that the upper plate 211 does not shift or move after being mounted. According to the configuration of the assembly guide ribs 216 and the rib insertion grooves 211a of the present invention, when mounting the upper plate 211 on the U-shaped frame 212, the rib insertion grooves 211a are simply sandwiched and aligned with the assembly guide ribs 216 of the pair of side plates 214 and 215 in a one-to-one correspondence, which greatly simplifies the assembly process.

[0058] In addition, the rib insertion groove 211a and the assembly guide rib 216 are configured to fit together when they intersect with each other. For example, the rib insertion groove 211a and the assembly guide rib 216 may be configured to have an interference fit so that there is no gap.

[0059] As a result, after the upper plate 211 and the U-shaped frame 212 are assembled, even if an external force acts on the upper plate 211, the upper plate 211 will not move in any direction, including forward, backward, leftward, or rightward. In this case, particularly when welding, the positions of the U-shaped frame 212 and the upper plate 211 will not shift relative to each other, significantly reducing the possibility of welding defects.

[0060] 4 and 5, the upper plate 211 may further include a double groove portion 211b recessed from the rib insertion groove 211a toward the center of the upper plate 211. The double groove portion 211b may be recessed with respect to the inner surface of the rib insertion groove 211a and may be provided so as not to come into contact with the assembly guide rib 216. As a result, when the assembly guide rib 216 of the side plates 214 and 215 is sandwiched vertically into the rib insertion groove 211a of the upper plate 211, an upper hole 218 may be formed that is surrounded by the double groove portion 211b and the assembly guide rib 216, as shown in FIG.

[0061] Therefore, the module case 200 according to an embodiment of the present invention includes the above-described upper hole 218 for each pressure relief portion PR, so that the pressure can be more effectively dispersed and relieved by the upper holes 218.

[0062] 4, 5 and 7, the side plates 214, 215 are arranged so that their upper end surfaces 214a contact the lower part of the edge region of the upper plate 211, and the pressure relief portion PR has a gap expansion portion 217 formed by recessing so as not to contact the lower part of the edge region of the upper plate 211.

[0063] That is, the upper plate 211 may be supported so that the lower portions of both edge regions thereof are mounted on the upper end surfaces 214a of the pair of side plates 214, 215 and positioned above the U-shaped frame 212. In the pressure relief portion PR, the side plates 214, 215 may have gap expansion portions 217 that are indented downward from the upper end surfaces 214a of the side plates 214, 215, as indicated by "T1" in FIG. 5. In this embodiment, the gap expansion portions 217 are provided at two locations, one on the left side and one on the right side of the assembly guide rib 216, but unlike this embodiment, they may be provided at either one location on the left side or the right side of the assembly guide rib 216, or at a location farther away from the assembly guide rib 216 than in this embodiment.

[0064] Such a configuration of the gap expansion portion 217 ensures a gap between the upper plate 211 and the side plates 214, 215, which are not welded together, making it even more effective in relieving the internal pressure of the module case 200.

[0065] FIG. 8 is a view showing the bottom surface of a battery module 10 according to an embodiment of the present invention.

[0066] The battery module 10 according to the present invention may further include a gas vent hole H.

[0067] The gas vent holes H may be provided in the bottom of the module case 200 that supports the battery cells 110. For example, the gas vent holes H may be provided in the lower plate 213 that forms the bottom of the module case 200. Specifically, according to this embodiment, the gas vent holes H may be located at both edges along the length of the lower plate 213, and the gas vent holes H may be spaced apart from each other in the width direction of the lower plate 213.

[0068] The position of the gas vent hole H corresponds to a position vertically below the cell terrace 112 on which the electrode lead 111 is provided in the pouch-type battery cell 110. In the case of a pouch-type battery cell 110, the electrode lead 111 side tends to be the highest temperature during thermal runaway. In addition, when the pouch-type battery cell 110 expands, the heat-sealed portion of the cell terrace 112 (front sealing portion or rear sealing portion) is easily torn, causing gas and flames to be emitted from that portion. In addition, when looking at the internal space of the module case 200 that houses the cell stack 100 formed by stacking the pouch-type battery cells 110, there is a lot of space where the thin cell terrace 112 is located. Therefore, when an internal fire occurs in the battery module 10, gas convection is most active where the cell terrace 112 is located. In the present invention, since the gas vent hole H is positioned vertically below the cell terrace 112, most of the gas generated during thermal runaway can be directionally vented downwards in the battery module 10.

[0069] A battery pack (not shown) according to the present invention includes one or more of the battery modules described above. 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 the charging and discharging of the battery modules, such as a battery management system (BMS), a current sensor, a fuse, etc.

[0070] Although terms indicating directions such as up, down, left, right, front, and back are used in this specification, it will be obvious to those skilled in the art that these terms indicate relative positions and are used only for convenience of explanation, and may vary depending on the position of the object in question, the position of the observer, etc.

[0071] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary skill in the art to which the present invention pertains to make various modifications and variations within the scope of the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0072] 10 Battery Module 100 cell stack 110 Pouch-type battery cell 110 battery cells 111 Electrode lead 112 Cell Terrace 120 Busbar frame assembly 121 Busbar frame 123 Busbar 200 Module Case 210 Case body 211 Upper Plate 211a Rib insertion groove 211b Double groove section 212 U-shaped frame 213 Lower Plate 214 Side Plate 214a Top surface 215 Side Plate 216 Assembly guide rib 217 Gap expansion section 218 Upper Hall 220 End cover 230 End cover H Gas vent hole PR Pressure relief section W1 Weld bead W2 weld bead

Claims

1. at least one battery cell; a module case having an internal space and accommodating the battery cells, The battery module, wherein the module case includes a weld bead portion where welding is performed at an edge line where one plate of the module case contacts another plate, and a pressure relief portion where welding is not performed and a gap is formed.

2. The pressure relief unit is 2. The battery module according to claim 1, wherein the battery cell is disposed at an upper end of the module case to cover an upper portion of the battery cell, and a plurality of the battery cell is provided at predetermined intervals along a longitudinal direction of the module case.

3. The module case includes: a case body that surrounds the upper, lower, left, and right surfaces of the internal space; The battery module according to claim 1 , further comprising: end covers covering the front and rear surfaces of the interior space and coupled to the case body.

4. The case body includes: an upper plate covering an upper surface of the internal space; 4. The battery module according to claim 3, further comprising: a U-shaped frame integrally formed with a lower plate covering a lower surface of the internal space and a pair of side plates covering the left and right surfaces of the internal space.

5. The module case includes:

5. The battery module according to claim 4, wherein both edge lines along the longitudinal direction of the upper plate and edge lines at the upper ends of the pair of side plates along the longitudinal direction are welded together except for the pressure relief portion.

6. In the pressure release section, 5. The battery module according to claim 4, wherein the upper plate includes a rib insertion groove recessed in a direction intersecting with the side plate, and the side plate includes an assembly guide rib inserted perpendicularly into the rib insertion groove.

7. The battery module according to claim 6, wherein the rib insertion groove and the assembly guide rib are provided to be fitted together.

8. The upper plate further includes a double groove portion recessed toward the center of the upper plate in the rib insertion groove, The battery module according to claim 6 , wherein the module case includes an upper hole surrounded by the double groove portion and the assembly guide rib.

9. 5. The battery module according to claim 4, wherein an upper end surface of the side plate contacts a lower portion of the edge region of the upper plate, and the pressure relief portion includes a gap expansion portion formed by being recessed so as not to contact the lower portion of the edge region of the upper plate.

10. The module case includes: The battery module according to claim 1 , wherein the bottom supporting the lower portion of the battery cell comprises at least one gas vent hole.

11. the battery cell is a pouch-type battery cell, The battery module according to claim 10, wherein the gas vent hole is provided vertically below a cell terrace where an electrode lead is provided in the pouch-type battery cell.

12. A battery pack comprising a battery module according to any one of claims 1 to 11.

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