Battery module and Battery Pack including the same

Abstract

A battery module according to the present invention comprises at least one battery cell; and a module case having an internal space to accommodate the battery cell, wherein the module case comprises weld bead portions where welding is performed at a corner line where one plate and another plate meet; and a pressure relief portion having a gap where welding is not performed.

Description

Technology Field

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

[0002] With the significant increase in technological development and demand for various mobile devices, electric vehicles, and energy storage systems (ESS), interest in and demand for secondary batteries as an energy source are rapidly rising. While nickel-cadmium and nickel-hydrogen batteries were conventionally widely used as secondary batteries, lithium-ion batteries are now being widely utilized. Compared to nickel-based batteries, lithium-ion batteries exhibit almost no memory effect, allowing for free charging and discharging, have a very low self-discharge rate, and possess high energy density.

[0003] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. The lithium secondary battery comprises an electrode assembly in which a positive plate and a negative plate, each coated with the positive and negative active materials, are arranged with a separator in between, and an outer casing, namely a battery case, that seals and houses the electrode assembly together with an electrolyte.

[0004] Generally, secondary batteries can be classified according to the shape of the casing into can-type batteries, in which the electrode assembly is embedded in a metal can, and pouch-type batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheet.

[0005] The lithium-ion batteries widely used recently have an operating voltage of approximately 2.5V to 4.5V per unit. Therefore, for electric vehicles or power storage devices requiring high capacity and high output, battery modules or battery packs consisting of multiple lithium-ion batteries connected in series and / or parallel are configured and used as an energy source. In particular, to satisfy the output or capacity required for electric vehicles, battery modules or battery packs contain a very large number of lithium-ion batteries.

[0006] Meanwhile, if a thermal event occurs in a battery module containing multiple battery cells and heat continuously accumulates inside the module, a thermal runaway phenomenon can rapidly propagate among the battery cells. In this case, damage can be severe, such as the explosion of the battery module.

[0007] Therefore, for the safety of the user, battery modules or battery packs need to be designed to suppress ignition or delay its spread in the early stages of a thermal event.

[0008] As is widely known, the three elements of combustion are fuel, oxygen, and heat. Among these, the battery cell, which corresponds to the fuel, is almost impossible to remove once a thermal event occurs. Consequently, there is a growing need for battery modules capable of effectively discharging heat sources to the outside to suppress or delay the spread of thermal events. In particular, a solution is required because the risk of explosion increases significantly if the internal pressure of the battery module is not rapidly relieved in the event of internal ignition. The problem to be solved

[0009] The present invention was devised to solve the technical problem described above, and has one objective of providing a battery module capable of effectively dispersing and relieving internal pressure when a thermal event occurs inside the battery module.

[0010] The technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below. means of solving the problem

[0011] A battery module according to one aspect of the present invention comprises at least one battery cell; and

[0012] It includes a module case that accommodates the battery cell by having an internal space, and

[0013] The above module case may include weld bead portions where welding is performed at the corner line where one plate and another plate meet; and pressure relief portions where welding is not performed and a gap is provided.

[0014] The pressure relief member may be configured at the upper part of the module case covering the upper part of the battery cell and may be provided in multiple units at predetermined intervals along the length direction of the module case.

[0015] The above module case may include a case body that surrounds the upper, lower, left, and right sides of the internal space; and an end cover that covers the front and rear sides of the internal space and is coupled to the case body.

[0016] The above case body may include a top plate covering the upper side of the internal space; a bottom plate covering the lower side of the internal space; and a U-frame integrally formed with a pair of side plates covering the left and right sides of the internal space.

[0017] The above module case may have both corner lines along the longitudinal direction of the top plate and the upper corner line along the longitudinal direction of the pair of side plates welded together, excluding the pressure relief portion.

[0018] In the pressure relief portion above, the top plate is provided with a rib fitting groove indented in a direction intersecting the side plate, and the side plate may be provided with an assembly guide rib inserted vertically into the rib fitting groove.

[0019] The above rib fitting groove and the above assembly guide rib can be provided to match the shape.

[0020] The top plate further comprises a double groove portion indented inward toward the center of the top plate from the rib fitting groove, and the module case may include an upper hole formed in a shape surrounded by the double groove portion and the assembly guide rib.

[0021] The above side plate may have an upper surface that contacts the lower part of the corner area of ​​the top plate, and the pressure relief portion may have a gap expansion portion formed by being recessed so as not to contact the lower part of the corner area of ​​the top plate.

[0022] The above module case may have at least one gas venting hole in the bottom portion that supports the lower part of the battery cell.

[0023] The above battery cell is a pouch-type battery cell, and the gas venting hole may be provided in the vertical lower part of the cell terrace where the electrode lead is provided in the pouch-type battery cell.

[0024] According to another aspect of the present invention, a battery pack comprising the battery module described above may be provided. Effects of the invention

[0025] According to one aspect of the present invention, a battery module capable of effectively dispersing and relieving internal pressure when a thermal event occurs inside the battery module may be provided.

[0026] In addition to the above, the present invention may have various other effects, which are described in each embodiment, or effects that can be easily inferred by those skilled in the art, etc., will be omitted. Brief explanation of the drawing

[0027] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a schematic perspective view of a battery module according to one embodiment of the present invention. Figure 2 is a schematic exploded perspective view of the battery module of Figure 1. Figure 3 is a side view of the battery module of Figure 1. FIG. 4 is a perspective view showing an assembly guide rib and a rib fitting groove of a module case according to one embodiment of the present invention. Figure 5 is a drawing of the assembly guide rib and rib fitting groove of Figure 4 viewed from a different angle. FIG. 6 is a plan view of a portion of the upper surface of a battery module according to one embodiment of the present invention. Figure 7 is an enlarged view of area A of Figure 3. FIG. 8 is a drawing showing the lower surface of a battery module according to one embodiment of the present invention. Specific details for implementing the invention

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. 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 in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely one preferred embodiment of the present invention and do not represent all aspects of the technical spirit of the present invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0029] In the drawings, the size of each component or specific part constituting the component is exaggerated, omitted, or schematically depicted for convenience and clarity of explanation. Accordingly, the size of each component does not entirely reflect its actual size. If it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such description shall be omitted.

[0030] 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. 1.

[0031] Referring to these drawings, a battery module (10) according to one embodiment of the present invention includes at least one battery cell (110) and a module case (200) having an internal space capable of accommodating the battery cell (110).

[0032] As will be described in detail later, the module case (200) according to the present invention includes weld bead portions (W1, W2) where welding is performed and a pressure relief portion (PR) where welding is not performed and a gap is provided at the corner line where one plate and another plate meet. Since the bonding strength between the plates of this module case (200) is high, deformation does not easily occur even with swelling of, for example, battery cells (110), and in the event of a thermal event in the battery module (10), the internal pressure of the module case (200) can be effectively dispersed and relieved.

[0033] For example, the pressure relief section (PR) may be provided in multiple units at predetermined intervals along the length direction (Y direction) of the module case (200) at the top of the module case (200) that covers the top of the battery cell (110), as shown in FIG. 1. When the internal pressure of the module case (200) increases, the plates at each pressure relief section (PR) separate to allow gas to leak out, thereby dispersing and relieving the internal pressure in multiple places.

[0034] Below, we will examine the main components of the battery module (10) according to the present invention in more detail.

[0035] First, the battery cell (110) included in the battery module (10) may be a pouch-type secondary battery having a thin plate-like body.

[0036] The above pouch-type secondary battery comprises a pouch outer material, an electrode assembly provided to be housed in the pouch outer material, and an electrolyte. For example, the pouch-type outer material may be composed of two pouches, and at least one of them may have a concave internal space formed therein. An electrode assembly may be housed in the internal space of such a pouch. The perimeters of the two pouches may be fused together so that the internal space housing the electrode assembly can be sealed. An electrode lead (111) may be attached to the electrode assembly, and the electrode lead (111) may function as an electrode terminal of the pouch-type secondary battery by being interposed between the fused portions of the pouch outer material and exposed to the outside of the pouch outer material. Here, the fused portion of the pouch outer material where the electrode lead (111) is located among the perimeters of the pouch outer material is referred to as a cell terrace.

[0037] These pouch-type secondary batteries can form a cell stack (100) that is vertically oriented and stacked horizontally, as shown in FIG. 2, and can be intensively stored in a module case (200).

[0038] A busbar frame assembly (120) can be used to electrically connect the above pouch-type secondary batteries.

[0039] The above busbar frame assembly (120) is generally composed of a busbar frame (121) which is a plastic injection molded product and busbars (123) provided in the form of metal rods such as copper, aluminum, or nickel that have electrical conductivity, and can be positioned at the front and / or rear of the cell stack (100).

[0040] The above busbar (123) may be configured to be in direct contact with the electrode lead (111) of the pouch-type secondary battery. In particular, the busbar (123) may be configured to maintain contact with the electrode lead (111) by means such as welding.

[0041] For example, the positive leads of N (N is a natural number) pouch-type battery cells (110) and the negative leads of N other pouch-type battery cells (110) are welded to the same busbar (123), so that the pouch-type battery cells (110) can be connected in series and / or parallel. The busbar frame (121) may be provided in the form of a roughly plate-like body having lead slits on one side that can secure the busbars (123) and allow the electrode leads (111) to be pulled out.

[0042] Meanwhile, the battery cell (110) constituting the battery module (10) according to the present invention does not necessarily have to be a pouch-type secondary battery. It should be noted in advance that a pouch-type secondary battery is merely one example of a battery cell (110) that can be applied to the battery module (10) of the present invention. That is, any type of secondary battery disclosed at the time of filing the present invention can be a battery cell (110) constituting the battery module (10) according to the present invention.

[0044] The above module case (200) may have its main parts made of a metal material with high mechanical strength so as to protect the battery cells (110) and other internal parts from external impacts, etc.

[0045] Referring mainly to FIGS. 1 and 2, a module case (200) according to one embodiment of the present invention may include a case body (210) provided in a shape that surrounds the upper, lower, left, and right sides of an internal space in which battery cells (110) are accommodated, and an end cover (220, 230) provided in a shape that covers the front and rear sides of the internal space and is coupled to the case body (210).

[0046] The above case body (210) may be configured in a roughly rectangular tubular shape with both ends open along the length direction, covering the upper surface, lower surface, and both sides of the cell stack (100), excluding the front and rear of the cell stack (100) (the direction in which the electrode lead (111) is located in the pouch-type battery cell (110)). The end covers (220, 230) may be configured to cover the openings of the case body (210). Additionally, the end covers (220, 230) may be configured so that the busbar frame assembly (120) is not exposed to the outside, except for a part of the busbar (123) which can function as an electrode terminal of the battery module (10) and has an insulated inner surface.

[0047] In the following, regarding the case body (210), the portion covering the upper side of the internal space of the module case (200) (or the upper surface of the cell stack (100)) is defined as a top plate (211), the portion covering the lower side of the internal space (or the lower surface of the cell stack (100)) is defined as a bottom plate (213), and the portion covering the left and right sides of the internal space (or the two side surfaces of the cell stack (100)) is defined as a pair of side plates (214, 215).

[0048] A case body (210) according to one embodiment of the present invention may be composed of the top plate (211) and a U frame (212). Here, the U frame (212) refers to a component in which the bottom plate (213) and the pair of side plates (214, 215) are integrated.

[0049] Specifically, the case body (210) may be provided in a form in which the top plate (211) and the U frame (212) shown in FIG. 2 are welded together as in FIG. 1. For example, a cell stack (100) may be placed inside the U frame (212), and the top plate (211) may be welded to the top of the U frame (212). And the end covers (220, 230) may also be mutually fixedly joined to the case body (210) by welding.

[0050] In this way, the case body (210), which is provided in a form in which a cell stack (100) is housed in a U frame (212) and a top plate (211) is welded to the top of the U frame (212), makes it easier to house the cell stack (100) compared to the case in which the cell stack (100) is originally provided in a rectangular tubular shape. In addition, when the cell stack (100) is pressed by a pair of side plates (214, 215) and the top plate (211) and the U frame (212) are welded as in FIG. 1, the gap between the pair of side plates (214, 215) is maintained at a constant level, so that the pressing force continues to act on the cell stack (100). In this case, there is an effect of suppressing or mitigating the swelling phenomenon of the battery cells (110) that may occur during charging and discharging.

[0051] As described above, the module case (200) according to the present embodiment is welded together with the U frame (212) and the top plate (211) or with the case body (210) and the end cover (220, 230). Accordingly, the module case is provided with weld bead portions (W1, W2) as shown in FIGS. 1 to 3.

[0052] A module case (200) according to the present invention has at least one pressure relief portion (PR) on a corner line (along the longitudinal direction) of its upper surface. The upper corner line of the module case (200) is not entirely welded. That is, the module case (200) has weld bead portions (W1) and a pressure relief portion (PR) that is an unwelded section on its upper surface.

[0053] The above pressure relief unit (PR) can be configured to allow air to flow in and out of the module case (200).

[0054] For example, the top of the U-frame (212), that is, the top edge line of a pair of side plates (214, 215) and the two edge lines of the top plate (211), may be welded while skipping certain sections, thereby providing weld bead sections (W1) and unwelded sections on both edges of the top surface of the module case (200). The pressure relief section (PR) is provided in the unwelded section and has a gap. Here, the gap may refer to a part or space where the side plates (214, 215) and the top plate (211) separate due to internal pressure.

[0055] Therefore, when a thermal event occurs in the battery module, gas can escape to the outside through the gap of the pressure relief part (PR), so that the internal pressure of the battery module (10) does not rise rapidly.

[0056] In addition, the pressure relief section (PR) is configured in multiple locations at predetermined intervals along the two corner lines of the upper surface of the module case (200), so that gas can escape through the pressure relief sections (PR) at multiple locations. Therefore, the pressure caused by the gas is not concentrated in one pressure relief section (PR) but can be distributed to multiple pressure relief sections (PR).

[0057] Furthermore, referring to FIGS. 1 to 2 and FIGS. 4 to 6, the module case (200) includes an assembly guide rib (216) and a rib fitting groove (211a).

[0058] Specifically, in the pressure relief portion (PR), the top plate (211) is provided with a rib fitting groove (211a) that is indented in a direction intersecting the side plates (214, 215), and the side plates (214, 215) are provided with an assembly guide rib (216) that protrudes higher than the top surface (214a) of the side plates (214, 215) and is inserted vertically into the rib fitting groove (211a).

[0059] The assembly process of the above U-frame (212) and the above top plate (211) is performed first before welding. In order to improve welding quality, the top plate (211) must be accurately seated on the top of the U-frame (212), and it is important that the position of the top plate (211) does not become misaligned or move after it is seated. According to the configuration of the assembly guide rib (216) and the rib fitting groove (211a) according to the present invention, when the top plate (211) is seated on the U-frame (212), the rib fitting grooves (211a) can be fitted one-to-one with the assembly guide ribs (216) of a pair of side plates (214, 215), so the assembly process can be made very easy.

[0060] Additionally, the rib fitting groove (211a) and the assembly guide rib (216) are configured to be shaped correctly when joined in an intersecting manner. For example, the rib fitting groove (211a) and the assembly guide rib (216) can be configured to be forcibly fitted together without any gap.

[0061] Accordingly, after assembling the top plate (211) and the U frame (212), even if an external force is applied to the top plate (211), the top plate (211) does not move in the forward, backward, left, or right directions. In this case, especially when performing welding, the relative positions of the U frame (212) and the top plate (211) do not become misaligned, so the possibility of welding defects occurring can be significantly reduced.

[0062] Additionally, as illustrated in FIGS. 4 and 5, the top plate (211) may further be provided with a double groove portion (211b) that is further recessed inward toward the center of the top plate (211) from the rib fitting groove (211a). The double groove portion (211b) may be provided as a recessed portion relative to the inner surface of the rib fitting groove (211a) so as not to come into contact with the assembly guide rib (216). Accordingly, when the assembly guide rib (216) of the side plates (214, 215) is inserted vertically into the rib fitting groove (211a) of the top plate (211), an upper hole (218) surrounded by the double groove portion (211b) and the assembly guide rib (216) may be formed as shown in FIG. 6.

[0063] Accordingly, the module case (200) according to one embodiment of the present invention is provided with upper holes (218) as described above for each pressure relief part (PR). Therefore, pressure can be more effectively dispersed and relieved through the upper holes (218).

[0064] Referring again to FIGS. 4, 5 and 7, the side plate (214, 215) is provided such that its upper surface (214a) contacts the lower part of the corner area of ​​the top plate (211), and the pressure relief portion (PR) is provided with a gap expansion portion (217) formed by being recessed so as not to contact the lower part of the corner area of ​​the top plate (211).

[0065] That is, the top plate (211) can be supported so that the lower portions of both corner areas are seated on the upper surface (214a) of a pair of side plates (214, 215) and positioned on the upper portion of the U frame (212). In the pressure relief portion (PR), the side plates (214, 215) may have a gap expansion portion (217) that is recessed downward relative to the upper surface (214a) of the side plates (214, 215), as indicated by 'T1' in FIG. 5. In the present embodiment, the gap expansion portion (217) is provided in two places, on the left and right sides of the assembly guide rib (216); however, unlike the present embodiment, it may be provided in either the left or right side of the assembly guide rib (216), or in a position further away from the assembly guide rib (216) than in the present embodiment.

[0066] With this configuration of the gap expansion section (217), a gap can be reliably secured between the unwelded top plate (211) and the side plates (214, 215), which can be more effective in relieving internal pressure of the module case (200).

[0067] FIG. 8 is a drawing showing the lower surface of a battery module (10) according to one embodiment of the present invention.

[0068] The battery module (10) according to the present invention may further include gas venting holes (H).

[0069] The above gas venting holes (H) may be provided in the bottom portion of a module case (200) that supports battery cells (110). For example, gas venting holes (H) may be provided in a bottom plate (213) that forms the bottom portion of the module case (200). Specifically, according to the present embodiment, the gas venting holes (H) are located at both edges along the length direction of the bottom plate (213), and each gas venting hole (H) may be spaced apart from one another in the width direction of the bottom plate (213).

[0070] The location of these gas venting holes (H) corresponds to the vertical lower portion of the cell terrace (112) where the electrode lead (111) is provided in the pouch-type battery cell (110). In the case of the pouch-type battery cell (110), the electrode lead (111) tends to have the highest temperature during thermal runaway. Additionally, when the pouch-type battery cell (110) expands, the thermal fusion portion of the cell terrace (112) (front sealing portion or rear sealing portion) breaks, making it easy for gas and flames to be discharged through that area. Furthermore, when looking at the internal space of the module case (200) housing the cell stack (100) formed by stacking pouch-type battery cells (110), there are many gaps in the areas where the thin cell terraces (112) are located. Therefore, when the battery module (10) ignites internally, gas convection is most active in the area where the cell terrace (112) is located. The present invention is configured such that a gas venting hole (H) is located at the vertical lower part of the cell terrace (112), so that most of the gas generated during thermal runaway can be directionally vented toward the lower direction of the battery module (10).

[0071] A battery pack (not shown) according to the present invention comprises 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 housing the battery modules, 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.

[0073] Meanwhile, although terms indicating directions such as up, down, left, right, front, and back have been used in this specification, these terms are used merely for convenience of explanation, and it is obvious to those skilled in the art that they may vary depending on the location of the object or the position of the observer.

[0074] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0075] 10: Battery module 100: Cell stack 110: Battery cell 120: Busbar frame assembly 200: Modular Case 210: Case body 211: Top Plate 211a: Rib insertion groove 211b: Double groove 212: U frame 213: Bottom Plate 214,215: Side plate 216: Assembly guide rib 217: Gap expansion 218: Upper Hole 220,230: End cover W1, W2: Weld bead section PR: Pressure relief unit H: Gas venting hole

Claims

Claim 1 A battery module comprising at least one battery cell; and a module case having an internal space to accommodate the battery cell, wherein the module case comprises weld bead portions where welding is performed at the corner line where one plate meets another plate; and a pressure relief portion having a gap where welding is not performed, wherein the module case comprises a case body surrounding the upper, lower, left, and right directions of the internal space; and an end cover covering the front and rear directions of the internal space and coupled to the case body, wherein the case body comprises a top plate covering the upper direction of the internal space; a bottom plate covering the lower direction of the internal space; and a U-frame integrally formed with a pair of side plates covering the left and right directions of the internal space, wherein in the pressure relief portion, the top plate has a rib fitting groove indented in a direction intersecting the side plate, and the side plate has an assembly guide rib inserted vertically into the rib fitting groove. Claim 2 A battery module according to claim 1, wherein the pressure relief member is configured at the upper end of the module case covering the upper part of the battery cell and is provided in a plurality at predetermined intervals along the longitudinal direction of the module case. Claim 3 delete Claim 4 delete Claim 5 A battery module according to claim 1, wherein the module case is characterized in that the two corner lines along the longitudinal direction of the top plate and the upper corner line along the longitudinal direction of the pair of side plates are welded, excluding the pressure relief portion. Claim 6 delete Claim 7 A battery module according to claim 1, characterized in that the rib fitting groove and the assembly guide rib are provided to be shaped to fit. Claim 8 A battery module according to claim 1, wherein the top plate further comprises a double groove portion indented inward toward the center of the top plate from the rib fitting groove, and the module case comprises an upper hole formed in a shape surrounded by the double groove portion and the assembly guide rib. Claim 9 A battery module according to claim 1, wherein the upper surface of the side plate contacts the lower part of the corner region of the top plate, and the pressure relief portion has a gap expansion portion formed by being recessed so as not to contact the lower part of the corner region of the top plate. Claim 10 A battery module according to claim 1, wherein the module case is characterized by having at least one gas venting hole in a bottom portion that supports the lower part of the battery cell. Claim 11 A battery module according to claim 10, wherein the battery cell is a pouch-type battery cell, and the gas venting hole is provided in the vertical lower part of the cell terrace where the electrode lead is provided in the pouch-type battery cell. Claim 12 A battery pack characterized by including a battery module according to any one of claims 1, 2, 5 and 7 through 11.

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