Battery module and method of manufacturing the same

Abstract

A battery module according to one embodiment of the present invention comprises a battery cell stack in which a plurality of battery cells are stacked in one direction, a module frame that accommodates the battery cell stack, and an end plate that is coupled to the module frame and covers the front or rear surface of the battery cell stack, wherein the module frame comprises a first layer and a second layer, and the melting point of the first layer is greater than the melting point of the second layer.

Description

Technology Field

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0079379 filed June 18, 2021, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] The present invention relates to a battery module and a method for manufacturing the same, and more specifically, to a battery module with enhanced safety and a method for manufacturing the same. Background Technology

[0004] In modern society, as the use of portable devices such as mobile phones, laptops, camcorders, and digital cameras has become commonplace, the development of technologies related to such mobile devices is becoming active. Furthermore, rechargeable secondary batteries are being utilized as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (P-HEVs) as a solution to address air pollution caused by conventional gasoline vehicles using fossil fuels; consequently, the need for the development of secondary batteries is increasing.

[0005] Currently commercialized rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention due to their advantages of free charging and discharging, low self-discharge rate, and high energy density.

[0006] Meanwhile, in the case of secondary batteries used in small devices, mainly 2-3 battery cells are used, but in the case of secondary batteries used in medium-to-large devices such as automobiles, a medium-to-large battery module in which multiple battery cells are electrically connected is used.

[0007] Since it is desirable for medium-to-large battery modules to be manufactured with the smallest possible size and weight, prismatic and pouch-type batteries, which can be stacked with high integration density and have a low weight-to-capacity ratio, are primarily used as battery cells for medium-to-large battery modules.

[0008] Battery cells mounted in a battery module can generate a large amount of heat during the charging and discharging process. If the temperature rises above the appropriate temperature due to reasons such as overcharging, performance may degrade, and if the temperature rise is excessive, there is a risk of explosion or ignition. If a thermal runaway phenomenon occurs within the battery module due to reasons such as overcharging, the internal temperature and internal pressure of the battery module rise significantly; consequently, the module frame or end plate forming the outer surface of the battery module may collapse due to the high temperature or high pressure. If the sealed structure of the battery module collapses in this manner, internal heat, gas, sparks, or flames are released to the outside, and a chain reaction of thermal runaway may occur as high-temperature battery cells or gas come into contact with external oxygen.

[0009] Conventionally, these problems were attempted to be solved mainly by filling the inner surface of the module frame with a heat-resistant shielding structure, but when a heat-resistant shielding structure is applied inside the battery module, the manufacturing cost increases, the manufacturing process becomes more complex, and the internal space of the battery module becomes more cramped.

[0010] Therefore, there is a need for technology capable of solving these problems of conventional technology. The problem to be solved

[0011] The problem that the present invention aims to solve is to provide a battery module with improved durability and safety by preventing continuous thermal runaway phenomena, and a method for manufacturing the same.

[0012] However, the problems that the embodiments of the present invention aim to solve are not limited to the problems described above and can be expanded in various ways within the scope of the technical ideas included in the present invention. means of solving the problem

[0013] A battery module according to one embodiment of the present invention comprises a battery cell stack in which a plurality of battery cells are stacked in one direction, a module frame that accommodates the battery cell stack, and an end plate that is coupled to the module frame and covers the front or rear surface of the battery cell stack, wherein the module frame comprises a first layer and a second layer, and the melting point of the first layer is greater than the melting point of the second layer.

[0014] The inner surface of the module frame may include the first layer, and the outer surface of the module frame may include the second layer.

[0015] The above module frame is a monoframe having a square tubular shape so as to accommodate the battery cell stack inside, and the monoframe can be formed by forming a plate into a tubular shape and then joining two ends of the plate.

[0016] A stepped portion not including the first layer is formed at the first end of the two ends, and a second end may be joined to the stepped portion of the first end.

[0017] Step portions that do not include the first layer are formed on each of the two ends, and the step portions can be joined together.

[0018] The above module frame may include a U-shaped frame in which either the upper or lower surface is open, and a straight cover that covers the open surface of the U-shaped frame.

[0019] Step portions not including the first layer are formed at each of the two ends of the above U-shaped frame, and the two ends of the straight cover can be joined to the step portions.

[0020] Step portions that do not include the first layer are formed at each of the two ends of the straight cover, and the two ends of the U-shaped frame can be joined to the step portions.

[0021] First stepped portions not including the first layer are formed at each of the two ends of the above U-shaped frame, and second stepped portions not including the first layer are formed at each of the two ends of the above straight cover, and the first stepped portions and the second stepped portions can be joined together.

[0022] Either of the above U-shaped frame and the above straight cover may not include the above first layer in its entirety.

[0023] The above module frame may include two U-shaped frames.

[0024] The respective ends of the two U-shaped frames can be joined facing each other to form one side of the module frame.

[0025] Each of the two ends of the above two U-shaped frames further includes flange portions extending outside the module frame, and the flange portions do not include the first layer, and the flange portions of the two U-shaped frames can be joined to each other.

[0026] One of the two U-shaped frames above may not include the first layer in its entirety.

[0027] The melting point of the first layer above may be 1000℃ or higher.

[0028] The thermal conductivity of the first layer may be lower than the thermal conductivity of the second layer.

[0029] The specific gravity of the first layer above may be greater than the specific gravity of the second layer above.

[0030] The thickness of the first layer and the thickness of the second layer may be different.

[0031] The ratio of the thickness of the first layer and the second layer may be 1:5 to 1:30.

[0032] The thickness of the first layer above may be 0.1 to 0.3 mm.

[0033] The thickness of the second layer above may be 1.5 to 3.0 mm.

[0034] The first layer above may comprise stainless steel, and the second layer may comprise aluminum, gold, silver, copper, platinum, or an alloy containing these.

[0035] The first layer and the second layer can be bonded through atomic diffusion junctions.

[0036] At least one of the corners of the module frame is formed through a bonding process, and a joint formed through the bonding process may exist in the second layer of the corner.

[0037] A method for manufacturing a battery module according to another embodiment of the present invention comprises the steps of forming a module frame that accommodates a battery cell stack, and combining the module frame with an end plate, wherein the step of forming the module frame comprises the steps of cutting a metal plate, forming the cut metal plate into a predetermined shape, removing one end of the metal plate, and joining one end of the metal plate, and wherein the module frame comprises a first layer and a second layer, and the melting point of the first layer is greater than the melting point of the second layer.

[0038] A battery pack according to another embodiment of the present invention includes at least one of the above-described battery modules. Effects of the invention

[0039] According to the embodiments, the battery module of the present invention includes a module frame capable of withstanding high temperature and high pressure, thereby maintaining its shape even in the event of internal ignition of the battery module and preventing a chain of thermal runaway phenomena.

[0040] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0041] FIG. 1 is a perspective view showing a battery module according to one embodiment of the present invention. Figure 2 is an exploded perspective view of a battery module according to Figure 1. Figure 3 is a cross-sectional view taken along AA of Figure 2. FIG. 4 is a drawing showing the structure of a module frame according to one embodiment of the present invention. FIG. 5 is a drawing for explaining a method of manufacturing a module frame according to an embodiment of the present invention. FIG. 6 is another drawing for explaining a method of manufacturing a module frame according to one embodiment of the present invention. FIG. 7 is another drawing for explaining a method of manufacturing a module frame according to one embodiment of the present invention. Specific details for implementing the invention

[0042] Hereinafter, various embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms other than those described below, and the scope of the present invention is not limited by the embodiments described herein.

[0043] To clearly explain the present invention, parts unrelated to the description have been omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0044] In addition, the size and thickness of each component shown in the drawings have been arbitrarily enlarged or reduced for convenience of explanation, so it is obvious that the content of the present invention is not limited to what is illustrated. In the drawings below, the thickness of each layer has been enlarged to clearly represent various layers and regions. Also, in the drawings below, the thickness of some layers and regions has been exaggerated for convenience of explanation.

[0045] Furthermore, when describing a part such as a layer, membrane, region, or plate as being "above" or "on" another part, this should be interpreted to include not only cases where the corresponding part is "directly above" the other part, but also cases where there is another part in between. Conversely, when describing a corresponding part such as a layer, membrane, region, or plate as being "directly above" another part, it may mean that there is no other part in between. Additionally, stating that a part is "above" or "on" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "on" in the opposite direction of gravity. Meanwhile, just as describing a part as being "above" or "on" another part can be understood by referring to the aforementioned content, describing a part as being "below" or "under" another part can also be understood.

[0046] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0047] Additionally, throughout the specification, "planar" refers to the part as viewed from above, and "cross-sectional" refers to the cross-section of the part cut vertically as viewed from the side.

[0049] A battery module according to one embodiment of the present invention will be described below.

[0050] FIG. 1 is a perspective view showing a battery module according to one embodiment of the present invention, and FIG. 2 is an exploded perspective view of the battery module according to FIG. 1.

[0051] Referring to FIGS. 1 and 2, a battery module (100) according to one embodiment of the present invention may include a battery cell stack (120) in which a plurality of battery cells (110) are stacked along one direction, a module frame (200) that accommodates the battery cell stack (120), and an end plate (400) that covers the front and / or rear of the battery cell stack (120).

[0052] The battery cell (110) according to the present embodiment may be provided in a pouch type in which the number of stacked cells per unit area can be maximized, but is not necessarily so and may also be provided in a prismatic or jelly roll cylindrical shape.

[0053] The module frame (200) according to the present embodiment may be intended to protect the battery cell stack (120) and the electrical components connected thereto from external physical impact. The module frame (200) may accommodate the battery cell stack (120) and the electrical components connected thereto in the internal space of the module frame (200). Here, the module frame (200) includes an inner surface and an outer surface, and the internal space of the module frame (200) may be defined by the inner surface.

[0054] Here, with reference to FIG. 1, the module frame (200) may have two faces facing each other on the z-axis and two faces facing each other on the y-axis, and the two faces facing each other on the z-axis may be referred to as the top surface (+z-axis direction) and the bottom surface (-z-axis direction), and the two faces facing each other on the y-axis may be referred to as the side surface. Also, the two faces facing each other on the z-axis may be referred to as the surface on the z-axis, and the two faces facing each other on the y-axis may be referred to as the surface on the y-axis.

[0055] The end plate (400) according to the present embodiment may be intended to protect the battery cell stack (120) and the electrical components connected thereto from external physical impact by sealing the open surface of the module frame (200). The structure of the module frame (200) may be provided in a hollow form open along the longitudinal direction of the battery cell stack (120), and the front and rear surfaces of the battery cell stack (120) may not be covered by the module frame (200). The front and rear surfaces of the battery cell stack (120) may be covered by the end plate (400), etc., thereby protecting the front and rear surfaces of the battery cell stack (120) from external physical impact, etc. To this end, the end plate (400) may be manufactured from a material having a certain strength. For example, the end plate (400) may include a metal such as aluminum.

[0056] Meanwhile, the module frame (200) may be manufactured primarily from a metal with high thermal conductivity for heat dissipation of the battery module (100), and examples of metals used in the module frame (200) may include aluminum, gold, silver, copper, platinum, or alloys containing these.

[0057] These metals are primarily used as materials for the module frame (200) because they have excellent thermal conductivity while satisfying the rigidity level required by the battery module (100), but there is a problem that their shape may collapse and accelerate thermal runaway when the battery module (100) ignites internally. Specifically, when thermal runaway occurs inside the battery module (100), the internal temperature may be 1000°C or 1200°C or higher, whereas the melting point of aluminum is 660°C, so it is difficult to maintain the external shape of the battery module (100) when it ignites internally.

[0058] In order to improve the heat resistance of the module frame (200), it is possible for the module frame (200) to be manufactured from steel or stainless steel, etc., with a melting point of 1400°C or higher. However, if the module frame (200) is manufactured from steel, the weight of the module frame (200) increases, so the lightweighting of the battery module (100) is not achieved, and there is a problem that the heat dissipation performance of the battery module (100) is reduced because the thermal conductivity of steel is lower than that of aluminum, etc.

[0059] Accordingly, the module frame of the present specification designed to solve the above-mentioned problem will be described below.

[0061] FIG. 3 is a cross-sectional view of one embodiment when cut along AA of FIG. 2.

[0062] Referring to the AA cross-section of the module frame (200) illustrated in FIG. 3, the module frame (200) of the present embodiment may include a first layer (210) and a second layer (220). The first layer (210) may be laminated on one side of the second layer (220). The second layer (220) may be laminated on one side of the first layer (210). The present invention is not limited to what is illustrated in FIG. 3, but includes cases where a part of the module frame (200) includes either the first layer (210) or the second layer (220).

[0063] When the direction from the inner surface of the module frame (200) toward the outer surface is called the first direction, the second layer (220) may be located in the first direction of the first layer (210). When the direction from the outer surface of the module frame (200) toward the inner surface is called the second direction, the first layer (210) may be located in the second direction of the second layer (220). In the module frame (200), the first layer (210) may be located closer to the inner surface of the module frame (200) than the second layer (220), and the second layer (220) may be located closer to the outer surface of the module frame (200) than the first layer (210). The second layer (220) ) It may be located outside the first layer (210). In the module frame (200), the first layer (210) may form the inner surface of the module frame (200), and the second layer (220) may form the outer surface of the module frame (200).

[0064] The first layer (210) and the second layer (220) included in the module frame (200) may have different physical properties. For example, the first layer (210) may be manufactured from a material with higher heat resistance than the second layer (220). If the first layer (210) is formed from a material with high heat resistance, the battery module (100) can maintain its shape even in the event of internal ignition, thus preventing oxygen from entering the battery module (100) or gas or sparks from being transmitted to other battery modules (100) due to the collapse of the module frame (200). Therefore, considering internal ignition of the battery module (100), it may be desirable for the first layer (210), provided with a material with high heat resistance, to form the inner surface of the battery module (100) or be located close to the inner surface. As another example, the second layer (220) may be manufactured from a material with a lower unit weight or specific gravity than the first layer (210), thereby reducing the total weight of the module frame (200). Additionally, the second layer (220) may be manufactured from a material with a higher thermal conductivity than the first layer (210), thereby improving the heat dissipation performance of the module frame (200).

[0065] The first layer (210) of the module frame (200) may be manufactured from a material with a higher melting point than the second layer (220). The first layer (210) of the module frame (200) may include a material that maintains its shape even under a temperature of 1000°C or 1200°C. The first layer (210) of the module frame (200) may include a material that maintains its shape even under a pressure of 2 bar or more. The first layer (210), provided as a material that maintains its shape even in such a high-temperature and high-pressure environment, may preferably form the inner surface of the battery module (100) or be located close to the inner surface. As a specific example, the first layer (210) may include stainless steel. As a specific example, the first layer (210) may include STS4xx, STS304, STS316, or other steel series.

[0066] The thickness of the first layer (210) of the module frame (200) may be 0.1 to 0.3 mm. Here, if the thickness of the first layer (210) is less than 0.1 mm, it may be difficult to ensure the heat resistance of the module frame (200). Also, here, if the thickness of the first layer (210) is greater than 0.3 mm, the total weight of the module frame (200) may increase, and the overall thermal conductivity of the module frame (200) may appear somewhat lower. Furthermore, if the manufacturing cost of the first layer (210) is somewhat high, a problem may also arise where the manufacturing cost of the module frame (200) increases as the thickness value of the first layer (210) increases.

[0067] The second layer (220) of the module frame (200) may be made of a material having a higher thermal conductivity than the first layer (210). The thermal conductivity of the second layer (220) is variable depending on its thickness, but may be 20 W / mk, 50 W / mk, 100 W / mk, or 150 W / mk or higher.

[0068] The second layer (220) of the module frame (200) may be manufactured from a lighter material with a lower unit weight, i.e., lower specific gravity, than the first layer (210). For example, the second layer (220) may include aluminum, gold, silver, copper, platinum, or alloys containing these. As a specific example, the second layer (220) may include A3xxx, A5xxx, A6xxx, or other aluminum. Since the specific gravity of aluminum is about 2.7, the difference may be about one-third when compared to steel, which has a specific gravity of 7.7 or higher.

[0069] The thickness of the second layer (220) of the module frame (200) may be 1.5 to 3.0 mm. Here, if the thickness of the second layer (220) is less than 1.5 mm, it is difficult to ensure the overall rigidity of the module frame (200), and if the thickness is greater than 3.0 mm, the overall thickness of the module frame (200) may increase more than necessary.

[0070] As such, the module frame (200) of the present embodiment may have improved heat resistance or corrosion resistance by additionally including a first layer (210) compared to a module frame (200) having only a second layer (220). At this time, if the first layer (210) forms the inner surface of the module frame (200) or is located close to the inner surface, the effect of the first layer (210) may be more pronounced. Also, the module frame (200) of the present embodiment may have its specific gravity reduced and its thermal conductivity improved by additionally including a second layer (220) compared to a module frame (200) having only a first layer (210), and the overall manufacturing cost may be reduced. Furthermore, as the rigidity and heat resistance of the module frame (200) are improved as described above, the battery module (100) of the present embodiment may minimize the use of additional heat-resistant materials and may not require a separate heat-resistant structure.

[0071] Meanwhile, although the above description is based on the module frame (200) having two layers, this is not necessarily the case, and the module frame (200) may be provided with three or more layers. Accordingly, the first layer (210) and the second layer (220) may be combined without a separate layer interposed between the two layers, but this is not necessarily the case, and the first layer (210) and the second layer (220) may be combined to include a separate layer interposed between the two layers. Also, a separate layer located in the first direction or the second direction of the first layer (210) or the second layer (220) may be added to the first layer (210) or the second layer (220).

[0072] Additionally, although the above description is based on the assumption that two layers are provided entirely in the module frame (200), this description does not exclude the possibility that two layers are provided partially in the module frame (200), and the case where the module frame (200) partially includes two layers should also be interpreted as being included in the content of the present invention. As will be described later, when the module frame (200) is formed by combining a plurality of sub-frames, only some of the plurality of sub-frames may be manufactured from a material having two layers, and the remainder of the plurality of sub-frames may be manufactured from a material having a single layer.

[0074] The module frame (200) of the present embodiment may be manufactured from a clad metal material comprising a first layer (210) and a second layer (220). Clad metal may be a general term for a material in which a metal or non-ferrous metal layer is used as the base layer to add new properties that the base material does not possess, and another metal or non-ferrous metal material is attached to one or both sides thereof. By joining two metals with different physical properties, the advantages of each are maintained and the disadvantages of each are complemented by each other, so the function of the clad metal can be further enhanced than the function of each metal.

[0075] Clad metal can be formed by methods such as welding, rolling, casting, or extrusion. Clad metal may comprise at least two metal layers, and since these layers are bonded via atomic diffusion bonding, they may be more difficult to delaminate than bonded via adhesives. Furthermore, in the case of heterogeneous metal bonding using clad metal, the two metal layers do not easily delaminate even when subjected to bending or external forces, and their bonding strength may further improve over time.

[0076] Meanwhile, it may be possible to use a coating process to manufacture a module frame (200) containing two metals having different physical properties. Specifically, a module frame (200) containing two layers may be manufactured by coating the inner surface of a module frame (200) formed from the material of the second layer (220) with the material of the first layer (210). However, considering the narrow internal space of the module frame (200), coating the inner surface of the module frame (200) is not only difficult to do, but even if possible, it is difficult to form a uniform coating layer. In addition, since various components including a battery cell stack (120) are placed in the internal space of the module frame (200), the aforementioned coating layer may be damaged during the process of inserting them into the interior of the module frame (200). In such cases, when manufacturing a module frame (200) containing two layers through a coating process, cracks may occur during the process of forming the coating layer, or during the process of accommodating other components in the internal space of the module frame (200) after the formation of the coating layer. In the event of internal combustion of the battery module (100), heat or pressure is transferred to the outer layer of the module frame (200), i.e., the second layer (220), through these cracks, and the module frame (200) may collapse accordingly; therefore, the durability of the module frame (200) manufactured through the coating process may be difficult to guarantee.

[0078] FIG. 4 is a drawing showing the structure of a module frame according to one embodiment of the present invention.

[0079] Referring to the cross-section of the module frame (200) illustrated in FIG. 4, the structure of the module frame (200) can vary.

[0080] For example, the module frame (200) may be a roll-press type monoframe (200a) as shown in FIG. 4(a). It may be provided with a structure in which a metal plate cut to accommodate the battery cell stack inside is formed into a hollow square tube shape, and the two ends (202a) of the metal plates that meet are vertically joined.

[0081] As another example, the module frame (200) may be provided with a structure in which a U-shaped frame (200b-1) with open front, rear, and top surfaces and a straight upper frame (200b-2) are combined, as shown in FIG. 4(b). The U-shaped frame may be formed by shaping a metal plate into a U-shape through a forming process. The U-shaped frame (200b-1) has a bottom surface and two sides, and the open top surface of the U-shaped frame may be covered by being combined with the upper frame (200b-2). The U-shaped frame (200b-1) and the upper frame (200b-2) may be joined by a bonding process with their corresponding ends (202b-1, 202b-2) in vertical contact. In addition, as opposed to the case of FIG. 4(b), a structure may be provided in which a U-shaped frame with open front, rear, and bottom surfaces is combined with a straight lower frame. Likewise, the U-shaped frame and the upper frame may be joined by a joining process with their corresponding ends in vertical contact. For convenience, the drawing is omitted, and other details may be explained in the same way using the vertically symmetrical drawing of FIG. 4(b).

[0082] As another example, the module frame (200) may have a structure in which two U-shaped frames (200c) are combined, as shown in FIG. 4(c). Flange portions (204c) may be formed at both ends (202c) of the two U-shaped frames (200c), and the two U-shaped frames (200c) may be joined by joining the flange portions (204c). That is, the flange portions on both sides of the upper U-shaped frames and the corresponding flange portions (204c) on both sides of the lower U-shaped frames may be joined by a joining process while facing each other and in contact. The lengths of the flange portions of the upper U-shaped frames and the flange portions of the lower U-shaped frames may be the same or different. The flange portions (204c) may not include a first layer.

[0083] Likewise, in FIG. 4(d), the structure may also have two U-shaped frames (200d) joined together. In FIG. 4(d), unlike FIG. 4(c), the flange portion is not included, and the two ends (202d) of the two U-shaped frames (200d) can be joined by a joining process while in a state where they are in contact with each other. That is, the two ends of the upper U-shaped frames and the corresponding two ends of the lower U-shaped frames can be joined by a joining process while in a state where they are in contact with each other. Accordingly, the corresponding two ends (202d) of the upper U-shaped frames and the lower U-shaped frames can be located on one side of the module frame (200), and the joining surface formed by joining the corresponding two ends (202d) can also be located on one side of the square tube shape.

[0084] Referring to FIG. 4(e), the module frame (200) may be a roll-press type monoframe (200e). It may be provided with a structure in which a metal plate cut to accommodate the battery cell stack inside is formed into a hollow square tube shape, and the two ends of the metal plates that meet are joined. At this time, the two ends of the formed metal plate may be located on one side of the square tube shape, and the joining surface formed by joining the two ends may also be located on one side of the square tube shape.

[0085] The structure of the module frame (200) may be provided in various shapes other than the examples described above, and may be provided in an L-shaped frame structure or various structures not described.

[0086] Here, for the forming process, any conventional method and device capable of forming the metal plate into a tubular or U-shape may be used, and a press process can be cited as an example. Also, for the joining, any conventional method may be followed as long as the joining state can be firmly maintained, and examples include laser welding, plasma welding, and TIG welding. In the structure of each module frame (200) shown in FIG. 4, the joining location is indicated as 'welding'. Although the welding area (welding) is shown as having a gap in FIG. 4, after joining by welding, it will have the shape of a module frame as shown in FIG. 3.

[0087] Also, in the case where a module frame (200) is formed by combining two or more subframes as in FIG. 4(b), FIG. 4(c), and FIG. 4(d), as in FIG. 7(a), the plurality of subframes may all be manufactured from metal plates having two or more layers, but this is not necessarily the case. It may also be possible for at least one of the plurality of subframes to be manufactured from a metal plate having two or more layers, and for the remainder of the plurality of subframes to be manufactured from a metal plate having a single layer, as in FIG. 7(b). FIG. 7(b) illustrates a case where the single-layer plate shown on the left is formed as a second layer (220), and the thickness of the second layer (220) in the two-layer plate shown on the right is greater than the thickness of the first layer (210). However, the present invention is not limited thereto, and it is also possible for the single-layer plate to be formed as a first layer (210), and for the thickness of the first layer (210) in the two-layer plate to be greater than the thickness of the second layer (220).

[0088] Meanwhile, when manufacturing a module frame (200) with a shape like that of FIG. 4, joining metal materials having multiple layers with different physical properties can be somewhat difficult. Since metals with different melting points are all exposed on the cross-section of the metal plate, when joining two ends using a welding process, which is a conventional joining method, it may be difficult for each layer present at the two ends to be completely bonded together. Therefore, when manufacturing the module frame (200) of the present embodiment, it may be preferable to perform the joining process after at least one of the multiple layers present at the two ends has been removed.

[0089] More specifically, referring to FIGS. 4(a), FIGS. 4(b), FIGS. 5(a), and FIGS. 5(b), when two ends of one or two metal plates form a corner, the first layer (210) and the second layer (220) located at each end meet perpendicularly to each other, so that one of the first layer (210) or the second layer (220), which have different physical properties, is removed and joined. FIG. 5 is a drawing for explaining a method of manufacturing a module frame according to an embodiment of the present invention. Referring to FIGS. 5(a) and FIGS. 5(b), one corner of the module frame (200) can be formed by joining two ends located at the ends of a metal plate or a sub-frame. Here, at least one of the two ends joined together through a joining process can be partially removed, and after being removed, it can be joined with the other end to form one corner of the module frame (200). At this time, the above-mentioned corner may be formed by combining the corner of one surface on the z-axis and the corner of one surface on the y-axis, and the module frame (200) of FIG. 4(a) includes at least one corner formed through the aforementioned combination, and the module frame (200) of FIG. 4(b) may include at least two corners formed through the aforementioned combination.

[0090] In the embodiment of FIG. 5(a), a step portion (230) is formed by removing the first layer (210) from one of the two ends of the metal plate, and the other end is joined to the step portion (230) of one end. Additionally, the case in which the second layers (220) of the two ends of the metal plate are joined to each other is illustrated.

[0091] In the embodiment of FIG. 5(b), a step portion (230) is formed by removing the first layer (210) from each of the two ends of the metal plate, and the step portion (230) of one end is joined to the step portion (230) of the other end. Additionally, the case in which the second layers (220) of the two ends of the metal plate are joined to each other is illustrated.

[0092] Specifically, when joining two ends of a metal plate or metal frame for manufacturing a module frame (200), since each layer of the two ends is arranged perpendicular to each other, the first layer (210) of one of the two ends may need to be joined to both the first layer (210) and the second layer (220) of the other end. Also, when heat is applied to the first layer (210) and the second layer (220) for joining between them, the first layer (210) and the second layer (220) melt together, causing a compound between the materials forming each layer to precipitate, and consequently, it may be difficult to form a joining surface. For example, if the first layer (210) contains Fe and the second layer (220) contains Al, the precipitated compound may be an Al-Fe compound.

[0093] However, as illustrated in FIG. 5(a), when at least one of the first layers (210) of the two ends is removed, the second layers (220) of each end come into contact with each other, so the two ends can be joined relatively easily through the bonding of the second layers (220), which have a relatively low melting point. At this time, a step can be formed in one of the two ends through the removal of the first layer (210), and since the position of the two ends is fixed through the step, the subsequent joining process can be made easier. In FIG. 5, it is shown that not only the first layer (210) but also the second layer (220) is removed to some extent, but this is not necessarily the case, and the removed portion may be designed differently depending on the appropriate size of the step and various process reasons.

[0094] Here, a bonding process for joining the two ends may be performed at a location where the second layers (220) of the two ends come into contact with each other. A heat source, such as a laser beam, may be provided for bonding the two ends, and the direction of the heat source may be parallel to the bonding surface where the two ends come into contact. Alternatively, the direction of the heat source may be a direction that forms a first angle with the bonding surface where the two ends come into contact. Here, the first angle may be 30 degrees or less, or between 15 degrees and 30 degrees or less. A bonding surface may be formed between the second layers (220) of the two ends. Specifically, a bonding surface may be formed by the contact between the second layer (220) exposed on the cross-section of one of the two ends and the second layer (220) of the other end revealed through a removal process. The portion of the module frame (200) that is mutually bonded by melting by a heat source may be referred to as a bonding portion. A bonding portion may be formed on the second layer (220). The joint may be formed in a stepped portion. The joint may have a shape in which the radial cross-section is reduced along the direction of heat supply. The axial cross-sectional shape of the joint is exemplified as 'weldment' in FIG. 5.

[0095] Meanwhile, the above description focused on removing the first layer (210) from one of the two ends in contact when forming the structure of the module frame (200) and then joining them, but this applies equally to cases where the first layer (210) is removed from both ends and then joined, as shown in FIG. 5(b). FIG. 6 is another drawing for explaining a method of manufacturing a module frame according to an embodiment of the present invention.

[0096] Referring to FIG. 6, the module frame (200) can be formed by combining flange portions (204c) included in two U-shaped frames as in FIG. 4(c).

[0097] Specifically, in joining two flange portions (204c) together for manufacturing a module frame (200), the two flange portions (204c) may be arranged so that a first layer (210) located on an inner surface comes into contact with each other. In order to join the two flange portions (204c), a heat source must be applied to the first layer (210) through a second layer (220) located on an outer surface, but joining the first layer (210), which has a different melting point, through the second layer (220) can be very difficult. Also, when a heat source is applied to a metal plate having two layers, the first layer (210) and the second layer (220) melt together, causing compounds between the materials forming each layer to precipitate, and consequently, it may be difficult to form a bonding surface.

[0098] However, as shown in FIG. 6, if the first layer (210) of the two flange portions (204c) is removed, the second layer (220) comes into contact with each other, so the two flange portions (204c) can be joined relatively easily through the joining process of the second layer (220).

[0099] Here, the bonding process can be performed at the contact portion of the second layer (220). Referring to FIG. 6(a), the lengths of the flange portions (204c) of the U-shaped frame facing each other may be the same. In this case, a heat source may be provided in a direction that forms an acute angle with respect to the direction from one flange portion toward the other flange portion. Also, referring to FIG. 6(b), the lengths of the flange portions (204c) of the U-shaped frame facing each other may be different. In this case, a heat source, such as a laser beam used in the bonding process, may be provided in a direction from one flange portion toward the other flange portion.

[0100] A joint surface may be formed between the second layer (220) of the two flange portions (204c). A joint may be formed in the second layer (220). The shape of the joint may vary depending on the direction of heat supply, and specifically, the joint may have a shape in which the radial cross-section is reduced along the direction of heat supply. The axial cross-sectional shape of the joint is exemplified as 'weldment' in FIG. 6.

[0101] Meanwhile, although the description in FIGS. 5 and 6 is based on the assumption that the first layer (210) is formed on the inner surface of the end or flange portion of the metal plate, the end or flange portion of the metal plate may include three or more layers depending on the design, and may include at least one additional layer located in the first direction or second direction of the first layer (210) in addition to the second layer (220). Accordingly, in such cases, the removal process described above should be appropriately performed to remove only the first layer (210) or to remove at least one of the additional layers as well as the first layer (210), taking into account the melting point or location of the additional layer.

[0102] FIG. 7 is another drawing for explaining a method of manufacturing a module frame according to one embodiment of the present invention.

[0103] Referring again to FIGS. 4(d) and FIGS. 4(e), two ends of a metal plate may be joined to form a surface. That is, the two ends are joined by facing each other's cross-sections on the same plane. At this time, the first layer (210) of one end of the metal plate may be joined to the first layer (210) of the other end, and the second layer (220) of one end may be joined to the second layer (220) of the other end. Thus, the two ends of the metal plate may be joined through a joining process as shown in FIG. 7(a), without involving the removal process described in FIGS. 5 and 6. Here, the joining of the two ends may be formed through the joining of the second layer (220) located at each end.

[0104] Here, the ends of the metal plates joined together may each have two layers as in FIG. 7(a), but as shown in FIG. 7(b), one may have one layer and the other may have two layers. Even in cases where at least one of the two ends is formed as a single layer, the two ends can be joined by joining a second layer (220) that contacts the two ends.

[0105] In addition, in FIGS. 4(a) and 4(d), when a single metal plate is bent to form a hollow square tube shape, the bent portion (i.e., the corner portion of the module frame) may be bent in a rounded shape or bent at a right angle. Likewise, in FIGS. 4(b), 4(c), and 4(e), when a U-shaped frame is formed by bending a single metal plate to form a U-shape, the bent portion (i.e., the corner portion of the module frame) may be bent in a rounded shape or bent at a right angle.

[0107] Hereinafter, a method for manufacturing a battery module according to one embodiment of the present invention will be described.

[0108] The method (S1000) for manufacturing a battery module (100) according to the present embodiment is,

[0109] Step (S1100) of forming a module frame (200) that accommodates a battery cell stack (120); and

[0110] It may include the step (S1200) of combining the module frame (200) and the end plate (400).

[0111] Here, the step (S1100) of forming a module frame (200) that accommodates a battery cell stack (120) may include the step of forming the module frame (200) and the step of mounting the battery cell stack (120) on the module frame (200), and these steps may be performed together. Specifically, when the module frame (200) is formed by combining a plurality of sub-frames, the step (S1100) of forming a module frame (200) that accommodates a battery cell stack (120) may include the step of providing one frame, the step of mounting the battery cell stack on the one frame, and the step of forming the module frame (200) by combining the one frame and another frame.

[0113] Hereinafter, a method for manufacturing a module frame according to one embodiment of the present invention will be described.

[0114] The manufacturing method (S2000) of the module frame (200) according to the present embodiment is,

[0115] Step of cutting a metal plate (S2100);

[0116] Step of forming a cut metal plate into a predetermined shape (S2200);

[0117] Step (S2300) of removing a portion of the end of a metal plate to form a stepped portion; and

[0118] It may include a step (S2400) of joining the ends of the metal plates.

[0119] Here, if the module frame (200) is formed in the manner shown in FIG. 7, step (S2300) may be omitted.

[0121] Hereinafter, a method (S2000) for manufacturing a module frame (200) according to the present embodiment will be described with reference to FIG. 4. The content described below may include all of the contents of FIG. 3 to FIG. 7 described above, and may be understood more specifically through the description above.

[0122] For example, in the case of the module frame (200) of FIG. 4(a), the metal plate is cut to a predetermined dimension and shape (S2100), and the cut metal plate can be formed into the shape of a square tube (S2200). Through the forming of the metal plate, the module frame (200) can have a bottom surface, two sides facing each other, and a top surface. Meanwhile, by forming the metal plate into a tube shape, the two ends (202a) of the metal plate can come into contact with each other, and by joining them, a roll-press type module frame (200a) can be formed. At this time, as described in FIG. 5, at least one of the two ends (202a) can be partially removed for easy joining of the two ends (202a) (S2300). A step portion (230) is formed through a removal process on at least one of the two ends (202a), and accordingly, the first layer (210) is partially removed so that the second layer (220) of the two ends (202a) can come into contact with each other, and the two ends (202a) can be joined together through step (S2400). Here, a heat source may be provided in the joining process of step (S2400) which joins one end and another end of a metal plate. The heat source used in the joining process is mainly provided in a direction parallel to the joining surface of the two ends or in a direction forming an acute angle with the joining surface, and accordingly, the shape of the joint may be determined.

[0123] As another example, in the case of the module frame (200) of FIG. 4(b), the metal plate is cut to predetermined dimensions and shapes to be manufactured into a U-shaped frame (200b-1) and a straight frame (200b-2), respectively (S2100), and one of the cut metal plates can be formed into a U-shape (S2200). Through the forming of the metal plate, a U-shaped frame having either a bottom or top surface and two sides can be formed, and a hollow module frame (200) can be formed by combining both ends of the U-shaped frame (200b-1) and both ends of the flat straight frame (200b-2). Specifically, the ends (202b-1) of the two sides of the U-shaped frame (200b-1) and the y-axis end (202b-2) of the flat upper frame (200b-2) can be combined. As described above, at least one of the end (202b-1) of the U-shaped frame and the end (202b-2) of the planar upper frame can be partially removed (S2300), thereby allowing the second layer (220) present at each end to come into contact with each other. By joining one end of one metal plate and one end of another metal plate (S2400), the second layer (220) of each end can be joined together. At this time, through the removal process (S2300), a step portion can be formed on at least one of the end of the U-shaped frame and the end of the planar upper frame.

[0124] As another example, in the case of the module frame (200) of FIG. 4(c), a metal plate is cut to a predetermined dimension and shape (S2100), and the cut metal plate can be formed into two U-shaped frames (S2200). The U-shaped frames (200c) have a bottom surface and two sides, and the module frame (200) can be formed by combining two U-shaped frames (200c). At this time, flange portions (204c) can be formed at both ends (202c) of the U-shaped frames, specifically at the ends (202c) of both sides, and the two U-shaped frames can be joined by joining the flange portions (204c) to each other. The flange portion (204c) may be a part that extends vertically from one side of the U-shaped frame, that is, from the side. The flange portions (204c) located on each of the two U-shaped frames are positioned to face the first layer (210), and the second layer (220) comes into contact with each other through the step (S2300) of removing the first layer (210), and can be joined together through the step (S2400) of joining one end of one metal plate and one end of another metal plate. At this time, a heat source used in the joining process of the step (S2400) may be provided. The heat source may be provided in a direction from one flange portion toward the other flange portion, or at an acute angle thereto, and the shape of the joint portion may be determined accordingly.

[0125] In the case of the module frame (200) of FIG. 4(d), refer to the description of FIG. 4(c), but the module frame (200) can be formed by combining both ends (202d) of the two U-shaped frames (200d) of FIG. 4(d) instead of the flange portion (204c) of FIG. 4(c). In the case of the module frame (200) of FIG. 4(e), refer to the description of FIG. 4(a), but two ends (202e) of a metal plate are joined facing each other on one side of the module frame (200).

[0126] Meanwhile, the metal plate described above may include at least two layers and may include the first layer (210) and the second layer (220) described above. Additionally, the metal plate including at least two layers may be a multi-bonded metal plate manufactured by a cladding method.

[0127] On the other hand, as shown in FIG. 4(b), FIG. 4(c), and FIG. 4(d), when two or more subframes are combined to form a module frame (200), it is possible for some of the multiple subframes to be provided as multi-bonded metal plates and the remainder of the multiple subframes to be provided as single metal plates. In this case, the single metal plate may be composed only of the second layer (220). Also, in this case, the part removed in step (S2300) may be the first layer (210) formed at one end of the multi-bonded metal plate, and the second layer (220) exposed through the removal process of the first layer (210) may come into contact with the single metal plate, and the two ends in contact with each other may be combined through step (S2400).

[0129] Meanwhile, the battery module (100) described above may be included in a battery pack. The battery pack may be a structure packed by adding a Battery Management System (BMS) that manages the temperature or voltage of the battery and a cooling device, etc., to the battery module according to the present embodiment.

[0130] Battery modules and battery packs containing the same can be applied to various devices. Such devices may be applied to means of transportation such as electric bicycles, electric vehicles, and hybrid vehicles, but the present invention is not limited thereto and can be applied to various devices capable of using battery modules and battery packs containing the same, and this also falls within the scope of the present invention.

[0131] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0133] 100: Battery module 110: Battery cell 120: Battery cell laminate 200: Module Frame 210: 1st floor 220: 2nd floor 230: Step section 300: Busbar Frame 400: End plate

Claims

Claim 1 A battery module comprising a battery cell stack having a plurality of battery cells stacked in a unidirectional manner, a module frame accommodating the battery cell stack, and an end plate coupled to the module frame and covering the front or rear surface of the battery cell stack, wherein the module frame comprises a first layer and a second layer, the melting point of the first layer is greater than the melting point of the second layer, the inner surface of the module frame comprises the first layer, the outer surface of the module frame comprises the second layer, the first layer comprises stainless steel, and the second layer comprises aluminum or an alloy containing the same. Claim 2 delete Claim 3 In claim 1, the module frame is a monoframe having a square tubular shape so as to accommodate the battery cell stack inside, and the monoframe is a battery module formed by forming a plate into a tubular shape and then joining two ends of the plate. Claim 4 A battery module according to claim 3, wherein a stepped portion not including the first layer is formed at the first end of the two ends, and a second end is joined to the stepped portion of the first end. Claim 5 A battery module according to paragraph 3, wherein stepped portions not including the first layer are formed on each of the two ends, and the stepped portions are interlocked and joined to each other. Claim 6 In claim 1, the battery module comprises a module frame having a U-shaped frame in which either the upper or lower surface is open, and a straight cover covering the open surface of the U-shaped frame. Claim 7 A battery module according to claim 6, wherein stepped portions not including the first layer are formed at each of the two ends of the U-shaped frame, and the two ends of the straight cover are joined to the stepped portions. Claim 8 A battery module according to claim 6, wherein stepped portions not including the first layer are formed at each of the two ends of the straight cover, and the two ends of the U-shaped frame are joined to the stepped portions. Claim 9 A battery module according to claim 6, wherein first stepped portions not including the first layer are formed at each of the two ends of the U-shaped frame, second stepped portions not including the first layer are formed at each of the two ends of the straight cover, and the first stepped portions and the second stepped portions are joined together. Claim 10 In claim 6, a battery module in which either the U-shaped frame and the straight cover does not include the first layer in its entirety. Claim 11 In claim 1, the module frame is a battery module comprising two U-shaped frames. Claim 12 In claim 11, a battery module in which the respective ends of the two U-shaped frames are joined facing each other to form one side of the module frame. Claim 13 A battery module according to claim 11, wherein each of the two ends of the two U-shaped frames further include flange portions extending outside the module frame, the flange portions do not include the first layer, and the flange portions of the two U-shaped frames are joined to each other. Claim 14 In claim 11, one of the two U-shaped frames is a battery module that does not include the first layer in its entirety. Claim 15 A battery module according to claim 1, wherein the melting point of the first layer is 1000℃ or higher. Claim 16 A battery module according to claim 1, wherein the thermal conductivity of the first layer is lower than the thermal conductivity of the second layer. Claim 17 A battery module according to claim 1, wherein the specific gravity of the first layer is greater than the specific gravity of the second layer. Claim 18 In claim 1, the thickness of the first layer and the thickness of the second layer are different in the battery module. Claim 19 A battery module according to claim 1, wherein the ratio of the thickness of the first layer to the second layer is 1:5 to 1:

30. Claim 20 A battery module according to claim 1, wherein the thickness of the first layer is 0.1 to 0.3 mm. Claim 21 A battery module according to claim 1, wherein the thickness of the second layer is 1.5 to 3.0 mm. Claim 22 delete Claim 23 In claim 1, the first layer and the second layer are joined through an atomic diffusion junction in a battery module. Claim 24 A battery module according to claim 1, wherein at least one of the corners of the module frame is formed through a bonding process, and a bond formed through the bonding process exists in the second layer of the corner. Claim 25 A method for manufacturing a battery module comprising the steps of forming a module frame that accommodates a battery cell stack and joining the module frame and an end plate, wherein the step of forming the module frame comprises: cutting a metal plate; forming the cut metal plate into a predetermined shape; partially removing one end of the metal plate; and joining one end of the metal plate to another end of the metal plate or one end of another metal plate, wherein the module frame comprises a first layer and a second layer, the melting point of the first layer is greater than the melting point of the second layer, the inner surface of the module frame comprises the first layer, the outer surface of the module frame comprises the second layer, the first layer comprises stainless steel, and the second layer comprises aluminum or an alloy containing the same. Claim 26 A battery pack comprising at least one battery module according to claim 1.

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