Battery module, battery pack and vehicle comprising the same

Abstract

A battery module according to the present invention comprises: a cell stack having a plurality of cells stacked thereon; a rectangular tubular monoframe housing the cell stack and having openings that are open on both sides; and an end frame coupled to the openings at the front and rear of the cell stack; wherein the monoframe is characterized by being made of a metal hollow material having a plurality of hollow portions that are extended in one direction and have both ends open, separated from each other, contained within a metal plate.

Description

Technology Field

[0001] The present invention relates to a battery module, and more specifically, to a battery module in which the module case is improved to enhance thermal safety. The present invention also relates to a battery pack and an automobile comprising such a battery module. Background Technology

[0002] Rechargeable batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles or hybrid vehicles powered by electric sources, and power storage devices. These rechargeable batteries are attracting attention as a new energy source for enhancing eco-friendliness and energy efficiency, not only for the primary advantage of drastically reducing the use of fossil fuels but also because they generate no by-products from energy use.

[0003] While small mobile devices use one or two or three cells per device, medium-to-large devices such as automobiles require high output and large capacity. Therefore, medium-to-large battery modules equipped with cell stacks in which multiple cells are electrically connected are used. Since it is desirable for medium-to-large battery modules to be manufactured with the smallest possible size and weight, prismatic cells and pouch-type cells, which can be stacked with high integration density and have a low weight-to-capacity ratio, are mainly used as unit cells for medium-to-large battery modules. Multiple of these cells are provided within a module case and electrically connected to each other to form a battery module. These battery modules can also be configured into a battery pack by electrically connecting one or more of them to each other.

[0004] Recently, there has been an increasing demand for high-capacity battery modules and packs used in electric vehicles and the like. Since these high-capacity battery modules and packs are equipped with multiple cells, their safety must be managed with greater strictness. This is because if thermal runaway, ignition, or explosion occurs in some cells within a single battery module, the generated high-temperature gas, flame, or high-temperature internal material can be sprayed and transferred to adjacent cells. As this transfer spreads to other adjacent battery modules, it can lead to secondary thermal runaway, secondary fire, or explosion, raising concerns that multiple cells may be triggered in a chain reaction of thermal runaway, ignition, or explosion. Therefore, there is a critical need for means to suppress or delay the transfer of flames between battery modules in the event of a thermal event such as thermal runaway. The problem to be solved

[0005] The present invention was conceived in consideration of the aforementioned problems, and the technical problem that the present invention aims to solve is to provide a battery module with enhanced safety against thermal runaway, fire, explosion, etc., that is, enhanced thermal safety.

[0006] However, 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

[0007] A battery module according to the present invention for solving the above-mentioned problem comprises: a cell stack having a plurality of cells stacked thereon; a rectangular tubular monoframe having openings that are open on both sides and housing the cell stack; and an end frame coupled to the openings at the front and rear of the cell stack. The monoframe is characterized by being made of a metal hollow material having a plurality of hollow portions that are elongated in one direction and have both ends open, separated from each other, contained within a metal plate.

[0008] The cell stack may have a plurality of cells including electrode leads on at least one side in the longitudinal direction stacked face-to-face, and the monoframe may surround the upper surface, lower surface, and both sides of the cell stack where the electrode leads are not formed, and the endframe may be positioned to face the electrode leads of the cell stack.

[0009] At this time, the above-mentioned hollow portion may be extended along the above-mentioned length direction.

[0010] According to one aspect of the present invention, the hollow portion in the metal hollow material may be included as a single layer.

[0011] At this time, in the metal hollow material, the height of the hollow part is 0.3-2 mm, the thickness of the metal layer above the hollow part and the thickness of the metal layer below the hollow part are 0.3-1 mm, and the spacing between the hollow parts may be 0.3-2 mm.

[0012] According to another aspect of the present invention, a stepped portion having a relatively thinner thickness than other parts may be included on the outer periphery of the opening side of the monoframe and on the outer periphery of the endframe.

[0013] For example, the outer surface of the opening side of the monoframe and the outer surface of the end frame may be flat, and the stepped portion may be formed by an inner depression.

[0014] Preferably, the stepped portion of the monoframe is a structure that compresses the hollow portion.

[0015] The above-mentioned stepped portion may be 0.3-2 mm thinner than other parts.

[0016] The stepped portion of the end frame may be formed by cutting the outer periphery of the end frame at a right angle.

[0017] In the present invention, the stepped portion of the end frame can be seated on the stepped portion of the mono frame.

[0018] The width of the stepped portion of the above end frame may be greater than the thickness of the top side wall of the above mono frame.

[0019] The stepped portion of the above end frame may be laser welded at the part that contacts the upper side wall of the above monoframe.

[0020] According to the present invention, the end frame may include a projection inserted into the hollow portion.

[0021] At this time, the above-mentioned protrusions may be inserted into each of the above-mentioned hollow parts, and the surface of the end frame that contacts the monoframe may be laser-welded.

[0022] In the present invention, an insulating air layer can be formed by the hollow portion.

[0023] The above metal hollow material may be manufactured by extrusion.

[0024] According to another aspect of the present invention, the surface of the metal hollow material may further include a ceramic coating layer composed solely of inorganic material without organic material.

[0025] Meanwhile, the battery pack and automobile according to the present invention include a battery module according to the present invention as described above. Effects of the invention

[0026] According to the present invention, by changing the module case, there is an effect of suppressing and delaying the progression of thermal runaway transition events within a unit module or between modules.

[0027] According to the present invention, even if thermal runaway, ignition, or explosion occurs in some cells within a single battery module, this is not transmitted to adjacent battery modules. Therefore, since multiple cells do not sequentially undergo thermal runaway, ignition, or explosion, secondary thermal runaway, secondary fire, or explosion does not occur.

[0028] Accordingly, according to the present invention, even if thermal runaway, fire, or explosion occurs in some of the plurality of cells, the thermal runaway, fire, or explosion may not propagate to adjacent battery modules. Therefore, it is possible to provide a battery module with improved safety against thermal runaway, fire, explosion, etc., that is, thermal safety, and a pack including the same and a vehicle. Brief explanation of the drawing

[0029] 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 an exploded perspective view showing a battery module according to one embodiment of the present invention. FIG. 2 is a perspective view showing the combined state of the components constituting the battery module of FIG. 1. FIG. 3 is a drawing showing a battery cell applied to a battery module according to one embodiment of the present invention. Figure 4 is a cross-sectional view along the line A-A' of Figure 2. Figure 5 is an enlarged view of section E of Figure 4. Figure 6 is a cross-sectional view along the line B-B' of Figure 2. Figure 7 is an enlarged view of part C of Figure 2. Figure 8 is another enlarged view of part E of Figure 4. FIG. 9 is a schematic diagram illustrating a battery pack according to one embodiment of the present invention. FIG. 10 is a schematic drawing illustrating an automobile according to one embodiment of the present invention. Specific details for implementing the invention

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, 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 some of the most preferred embodiments of the present invention and do not represent all 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.

[0031] FIG. 1 is an exploded perspective view showing a battery module according to an embodiment of the present invention. FIG. 2 is a perspective view showing the combined state of the components constituting the battery module of FIG. 1. FIG. 3 is a drawing showing a battery cell applied to a battery module according to an embodiment of the present invention.

[0032] Referring to FIGS. 1 to 3, a battery module (90) according to one embodiment of the present invention includes a cell stack (100) and a module case (200). The cell stack (100) has a plurality of cells (110) stacked thereon. The module case (200) includes a monoframe (210) and an endframe (230).

[0033] The cell stack (100) may be an assembly of secondary batteries composed of pouch-type cells (110) stacked with their wide surfaces facing each other. More precisely, the cell stack (100) may be an assembly of secondary batteries in which the cells (110) are stored within a module case (200) in a form in which they are vertically positioned (along the Z-axis direction) and stacked horizontally (along the Y-axis direction). Pouch-type cells (110) have the advantage of being easy to stack while having a high energy density relative to their size and weight. However, the cells (110) included in the battery module (90) according to the present invention are not limited to pouch-type cells only, and various types of secondary batteries known at the time of filing the present application may be employed.

[0034] The monoframe (210) is a rectangular tube body that accommodates the cell stack (100) and has openings (O) that are open on both sides. The monoframe (210) may be a rectangular tube body that forms openings (O) that are open on both sides in the longitudinal direction of the cell (110). The monoframe (210) may be formed as a rectangular tube body that opens on both sides facing each other and connects the remaining four sides.

[0035] The monoframe (210) has a very simple structure and has a space and shape suitable for accommodating a cell stack (100) inside, and is easy to handle as it only requires pushing the cell stack (100) through the opening (O), and has the advantage of easy assembly as the battery module (90) can be assembled by simply closing the opening (O). Therefore, the structure of the battery pack including the battery module (90) does not become complex and does not take up much space, and is simple and compact, and the assembly of the battery module (90) can be easily performed, so the processability can be excellent.

[0036] In addition, the monoframe (210) ensures secure fixation of the cell (110) without using parts such as conventional cell cartridges. Since it is not necessary to use a structure where the cell cartridge is inserted and pressed to fix the corners of the cell as in the past, the design margin of the entire battery module is increased, and the problem of shock or vibration being transmitted to the corners of the cell, which can occur when the corners of the cell are inserted into the cell cartridge in the past, can be resolved. The battery module (90) and battery pack containing such a monoframe (210) have an excellent effect of protecting the cell (110) against external vibrations, so they are advantageous for application in vehicles that are frequently exposed to external vibrations.

[0037] The end frame (230) is coupled to the opening (O) of the monoframe (210) at the front and rear of the cell stack (100). The end frame (230) may have a size and shape capable of covering the entire opening (O) of the monoframe (210). The coupling here may be by welding, bonding, or bolting, and preferably by welding. Since the monoframe (210) has openings (O) that are open on both sides in the longitudinal direction of the cell (110), the end frame (230) coupled to the opening (O) may be located at the front and rear of the cell stack (100), respectively. Additionally, the battery module (90) may further include a busbar frame (240) located between the cell stack (100) and the end frame (230).

[0038] When the two sides opened by the opening (O) of the monoframe (210) are respectively referred to as the first side and the second side, the monoframe (210) can cover the remaining outer surfaces, excluding the surfaces of the cell stack (100) corresponding to the first side and the second side. That is, the monoframe (210) can cover the upper surface, lower surface, and both sides of the cell stack (100).

[0039] The monoframe (210) may include four side walls corresponding to each of the four sides of the cell stack (100) in this manner. Each side wall may have a plate-like structure. The side walls may be formed integrally, so the monoframe (210) may be a single tubular member. That is, the monoframe (210) may refer to a structure in which four side walls corresponding to the four sides of the cell stack (100) are formed integrally.

[0040] The monoframe (210) is formed as a rectangular tube body with two sides facing each other open and the remaining four sides connected. It is a module case in which two sides, the top surface, and the bottom surface are integrated. Therefore, without requiring separate subsequent joining components such as welding, bolting, or hook fastening, the top, bottom, left side, and right side are all formed as a whole integrated form. Since there are no separate joining components on the sides, top surface, and bottom surface and they are formed as an integrated form from the beginning, the manufacturing process of the module case is simplified, the manufacturing time is shortened, and the rigidity of the module case can be effectively improved.

[0041] A thermally conductive resin layer may be further formed on the inner surface of the monoframe (210). After housing the cell stack (100) inside the monoframe (210), the thermally conductive resin may be injected into the monoframe (210) to fill the space inside the monoframe (210). This thermally conductive resin helps to dissipate heat generated from the cell (110) to the outside of the battery module (90).

[0042] As previously mentioned, a pouch-type cell may be applied as the cell (110) constituting the cell stack (100). When the cell (110) is a pouch-type cell, as shown in FIG. 3, the cell (110) may be implemented in a form including an electrode assembly (not shown), a pouch case (111), an electrode lead (112), and a sealing tape (113).

[0043] Although not illustrated in the drawing, the electrode assembly has a form in which a separator is interposed between alternately stacked positive and negative plates, and it is preferable that a separator be located at each of the outermost sides for insulation.

[0044] The above positive plate is composed of a positive current collector and a positive active material layer coated on one side thereof, and a positive non-coated area is formed at one end where the positive active material is not coated, and this positive non-coated area functions as a positive tab.

[0045] The above-described cathode plate is composed of a cathode current collector and a layer of cathode active material coated on one or both sides thereof, and a cathode-free region is formed at one end where the cathode active material is not coated, and this cathode-free region functions as a cathode tab.

[0046] In addition, the separator may be made of a porous material to prevent direct contact between electrode plates having different polarities by being interposed between the positive plate and the negative plate, while enabling the movement of ions between the positive plate and the negative plate using an electrolyte as a medium.

[0047] The cell case (111) includes two regions: a receiving portion (111a) that accommodates an electrode assembly, and a sealing portion (111b) that extends peripherically from the receiving portion (111a) and seals the cell case (111) by heat-fusing the electrode lead (112) so that it is pulled out to the outside.

[0048] Although not shown in the drawing, the cell case (111) is sealed by heat-sealing the edges of the upper case and the lower case, each of which is made of a multilayer pouch film in which a resin layer / metal layer / resin layer is sequentially laminated. The upper case and the lower case may be made of two sheets separated from each other or one sheet that is not separated and folded.

[0049] A pair of electrode leads (112) are each connected to a positive tab (not shown) and a negative tab (not shown) and are drawn out to the outside of the cell case (111). The pair of electrode leads (112) may have a structure in which they face each other and protrude from one end and the other end of the cell (110). The distance between the two ends from which the electrode leads (112) protrude from the cell case (111) may be defined in the longitudinal direction of the cell (110) (in this embodiment, the X-axis direction). In other types of pouch-type cells, the electrode leads may be formed on only one side. Thus, the cell (110) may include electrode leads (112) on at least one side in the longitudinal direction.

[0050] The sealing tape (113) is attached around the electrode lead (112) and is interposed between the inner surface of the sealing portion (111b) of the pouch case (111) and the electrode lead (112). The sealing tape (113) prevents the sealing performance of the sealing portion (111b) from being weakened due to the withdrawal of the electrode lead (112).

[0051] Multiple cells (110) can be stacked in the Y-axis direction as shown in FIG. 1. Multiple cells (110) can be stacked face-to-face. When the surface of the cell case (111) is slippery, multiple cells (110) tend to slide easily due to external impact when stacking. Therefore, to prevent this and maintain a stable stacking structure of the cells (110), an adhesive member such as a double-sided adhesive or a chemical adhesive that bonds through a chemical reaction upon bonding can be attached to the surface of the cell case (111) to form a cell stack (100). In this embodiment, the cell stack (100) is stacked in the Y-axis direction, inserted and accommodated inside a monoframe (210) in the X-axis direction, and cooling can proceed by the aforementioned thermally conductive resin. In a structure where the cells are contained and stacked in a cartridge-shaped component, due to the presence of the cartridge-shaped component, there is almost no cooling action or it may proceed in the face direction of the cells, and cooling does not occur well in the height direction of the battery module. The battery module (90) according to the embodiment of the present invention is well cooled in the height direction (Z-axis direction) of the battery module.

[0052] Before the cell stack (100) is inserted into the monoframe (210), a thermally conductive resin may be applied to the inner surface of the monoframe (210), particularly the bottom surface (the surface lying on the XY plane in the drawing), and the thermally conductive resin may be cured to form a resin layer. Before the thermally conductive resin layer is formed, that is, before the applied thermally conductive resin is cured, the cell stack (100) may be mounted inside the monoframe (210) by moving along the bottom surface of the monoframe (210) in the X-axis direction. Subsequently, the thermally conductive resin layer formed by the curing of the thermally conductive resin is located between the inside of the bottom surface of the monoframe (210) and the cell stack (100). The thermally conductive resin layer may serve to transfer heat generated from the cell (110) to the bottom of the battery module (90) and to fix the cell stack (100). Through the thermally conductive resin layer, heat generated from a plurality of cells (110) can be transferred to the outside through the bottom surface of the monoframe (210). The thermally conductive resin layer may include a thermal resin. There is no limitation on the type of thermal resin, and it may be, for example, any one of a thermally conductive silicone-based bond, a thermally conductive acrylic bond, or a thermally conductive polyurethane bond. As the thermally conductive resin layer, a urethane resin, epoxy resin, or silicone resin having excellent thermal conductivity and adhesive properties may be used. These materials can seep between the cells (110) to eliminate air layers, thereby reducing thermal resistance, and also have adhesive properties to prevent the flow of the cells (110) and stably support the bottom of the cell stack (100). The battery module (90) can be placed on a heat sink such that the bottom surface of the mono frame (210) contacts the heat sink (not shown).The heat of the cells (110) involved in the charging and discharging process can be rapidly dissipated through the thermally conductive resin layer, the bottom surface of the monoframe (210), and the heat sink.

[0053] The monoframe (210) wraps around the top surface, bottom surface, and both sides of the cell stack (100) where the electrode leads (112) are not formed in the cell stack (100). The end frame (230) is positioned to face the electrode leads (112) of the cell stack (100). This module case (200), comprising the monoframe (210) and the end frame (230), has an internal space capable of housing cells (110) inside, provides mechanical support for the housed cells (110), and serves to protect them from external impacts. The battery module (90) of the present invention is particularly improved in this module case (200) portion.

[0054] Figure 4 is a cross-sectional view along line A-A' of Figure 2. Figure 5 is an enlarged view of section E of Figure 4.

[0055] Referring to FIGS. 4 and 5, in the battery module (90), the monoframe (210) is characterized by being made of a metal hollow material that includes a plurality of hollow portions (224) that are elongated in one direction and open at both ends, separated from each other, within a metal plate (222). Here, the metal is preferably aluminum (Al) or an aluminum alloy. In this case, a monoframe (210) with excellent strength and lightness can be obtained.

[0056] The monoframe (210) is made of a thermally conductive material and is designed to absorb heat from the cell laminate (100) and dissipate it to the outside. The metal plate (222) is metallic and has excellent thermal conductivity, so the entire structure can perform a heat dissipation function. While any metal material can be used for the metal plate (222), it is preferable to use a SUS or aluminum series when considering thermal conductivity, processability, and cost. In terms of weight reduction, the aluminum series mentioned earlier is more advantageous.

[0057] In this embodiment, the hollow portion (224) extends along the length direction. The hollow portion (224) extends in a direction parallel to a pair of electrode leads (112). Since the hollow portion (224) extends along the protruding direction of the electrode leads (112) that generate relatively high heat in each cell (110), it has an excellent effect of blocking heat transfer between each cell (110).

[0058] As illustrated in detail in FIG. 5, the hollow portion (224) in the metal hollow material may be included as a single layer. To further increase the energy density of the battery module (90), it is necessary to reduce the thickness of the monoframe (210). Since the thickness of the monoframe (210) must be increased to include the hollow portion (224) as a multi-layer while maintaining the required strength of the monoframe (210), it is preferable to include it as a single layer. An insulating air layer can be formed by the hollow portion (224). That is, the hollow portion (224) is not filled with a separate refrigerant or additional components. The high insulating properties of the air layer are utilized without the need for a separate refrigerant circulation means or additional components. The hollow portion (224) is not intended to cool but rather to block heat transfer. By doing so, heat transfer to the outside is blocked even when there is a temperature change inside the battery module (90), and as a result, heat propagation to neighboring battery modules is blocked, thereby preventing a chain of thermal events and improving the safety of the battery module.

[0059] The cross-sectional structure of this monoframe (210) is such that a rectangular hollow section (224) is included in the middle of a metal plate (222) in a single layer, and the shape of the hollow section (224) and the spacing between the hollow sections (224) are constant, and the height (h) of the hollow section (224) is equal to or greater than the thickness (d1) of the metal layer above the hollow section (224) and the thickness (d2) of the metal layer below the hollow section (224). These height (h) and thickness (d1, d2) conditions are suitable for preventing heat propagation by increasing the volume occupied by the hollow section (224) as much as possible while maintaining the rigidity of the monoframe (210).

[0060] Conventional module cases are simple structures (solid type) in which the entire cross-sectional structure is filled with metals such as Al or SUS, and there is a problem of thermal runaway spreading to neighboring battery modules through heat conduction to the outside or inside. In other words, conventional module cases are structured such that they cannot prevent heat conduction and radiation when an event such as thermal runaway propagation occurs, and thus flames are transferred to neighboring battery modules. In the battery module (90) of the present invention, by changing the cross-sectional structure of the module case (200) as described above, it is possible to prevent flames from being transferred between battery modules when an event such as thermal runaway propagation occurs.

[0061] Most preferably, the monoframe (210) can be defined as having a hollow cross section that minimizes thermal runaway, such as heat conduction and heat radiation, by including multiple hollow sections (224) that are separated from each other and extend in one direction (in this embodiment, the longitudinal direction and X-axis direction) and have both ends open, within a metal plate (222) that is Al or an Al alloy, thereby forming an insulating air layer.

[0062] The above metal hollow material may be manufactured by extrusion. By adding a protrusion that allows the square tube to be extruded while forming a hollow portion in a mold that extrudes the square tube, a monoframe (210) containing a hollow portion (224) can be manufactured by extruding the square tube in a tubular shape. Along the extrusion direction, the hollow portion (224) has an elongated shape, and adjacent hollow portions (224) are formed parallel to each other along the extrusion direction. Compared to cases where the hollow structure exists in a disordered manner, such as in metal foam, the metal hollow material intended for use in the present invention has a difference in that it has a regular arrangement of hollow structures, and because the hollow portion (224) can be provided while controlling the height (h) of the hollow portion (224) and the spacing (p) between the hollow portions (224), precise control and management of the thermal insulation effect is possible.

[0063] According to a preferred example, the height (h) of the hollow portion (224) in the metal hollow material is 0.3-2 mm, the thickness of the metal layer (d1) above the hollow portion (224) and the thickness of the metal layer (d2) below the hollow portion (224) are 0.3-1 mm, and the spacing (p) between the hollow portions (224) may be 0.3-2 mm. The thickness (D) of the metal hollow material may be 1.5-4 mm. If the height (h) of the hollow portion (224) or the spacing (p) between the hollow portions (224) is less than 0.3 mm, the size of the hollow portion (224) is too small and the spacing becomes too dense, making it difficult to sufficiently exert an insulating effect. If the height (h) of the hollow portion (224) or the spacing (p) between the hollow portions (224) is greater than 2 mm, it is not desirable in terms of including as many hollow portions (224) as possible within a given space. If the thickness of the metal layer (d1) above the hollow portion (224) and the thickness of the metal layer (d2) below the hollow portion (224) are less than 0.3 mm, it is difficult to ensure rigidity while making the monoframe (210) thin and light. If the thickness of the metal layer (d1) above the hollow portion (224) and the thickness of the metal layer (d2) below the hollow portion (224) are greater than 1 mm, it is not desirable in terms of maximizing the inclusion of the hollow portion (224) within a given space. If the thickness (D) of the metal hollow material is less than 1.5 mm, it is difficult to ensure rigidity of the monoframe (210). If the thickness (D) of the metal hollow material is greater than 4 mm, it is not desirable because the size of the battery module (90) increases and the weight increases.

[0064] Here, the height (h), thickness (d1, d2, D), and spacing (p) are variable. The height (h), thickness (d1, d2, D), and spacing (p) are very small values ​​compared to the external dimensions of the battery module (90), which are hundreds of mm x hundreds of mm. It should be understood that this is a different dimension from the scale in the case where a channel is formed in the module case itself. Also, considering that the height (h) of the hollow portion (224) and the spacing (p) between the hollow portions (224) are 0.3-2 mm, it can be said that fine hollow portions (224) are densely formed. By making the thickness (D) of the metal hollow material 1.5-4mm and the height (h) of the hollow portion (224) and the spacing (p) between the hollow portions (224) 0.3-2mm, the monoframe (210) can be made thin and light while maintaining rigidity, and as many hollow portions (224) as possible can be included within the given space, thereby maximizing the thermal insulation effect.

[0065] To further increase the energy density of the battery module (90), it is necessary to reduce the thickness of the monoframe (210). However, when extruding a thin metal hollow material, the amount of material drawn out and molded is too small compared to the amount of material input, and as the thickness of the metal hollow material decreases, the pressure applied for extrusion increases, which may cause damage to the extrusion mold. In addition, as the thickness of the metal hollow material decreases, problems may arise such as the shape of the molded product becoming distorted or the thickness not being uniform. Therefore, the height (h), thickness (d1, d2, D), and spacing (p) can be determined by taking all these problems into account. By controlling variables during extrusion manufacturing, the height (h) of the hollow part (224) can be formed to be equal to or greater than the thickness of the metal layer (d1) above the hollow part (224) and the thickness of the metal layer (d2) below the hollow part (224), and the spacing (p) between the hollow parts (224) can also be formed very densely. Therefore, it has the advantage of excellent thermal insulation.

[0066] In the battery module (90), hollow portions (224) are located on the bottom surface, both sides, and the top surface of the cell stack (100). Since hollow portions (224) are located on all four sides of the cell stack (100), the effect of blocking heat propagation in all directions can be maximized.

[0067] The weld between the monoframe (210) and the endframe (230) may be formed by simple butt welding, but as shown in detail in FIG. 6, the weld may also be formed after forming the stepped portion (210a, 230a). FIG. 6 is a cross-sectional view along the line B-B' of FIG. 2.

[0068] Referring to FIG. 6, the monoframe (210) includes a stepped portion (210a) that is relatively thinner than other parts on the outer periphery of the opening side. The stepped portion (210a) is provided on the upper side wall of the monoframe (210). The endframe (230) includes a stepped portion (230a) that is relatively thinner than other parts on the outer periphery. The stepped portion (230a) may be provided at the edge of the endframe (230). The outer surface of the opening side of the monoframe (210) and the outer surface of the endframe (230) are flat, and the stepped portions (210a, 230a) may be formed by an inward depression.

[0069] Preferably, the stepped portion (210a) of the monoframe (210) is a structure formed by compressing the hollow portion (224). In such a case, the stepped portion (210a) has a thickness limited to the height (h) of the hollow portion (224) in the metal hollow material, so the stepped portion (210a) may be thinner than other parts by 0.3-2 mm, which is the height (h) of the hollow portion (224). Since the hollow portion (224) can be easily compressed even with a small amount of compression force, the stepped portion (210a) can be easily and precisely formed through compression processing.

[0070] The stepped portion (230a) of the end frame (230) may be formed by cutting the outer periphery of the end frame (230) at a right angle. The stepped portion (230a) of the end frame (230) may be seated on the stepped portion (210a) of the mono frame (210). The part where the stepped portion (230a) of the end frame (230) contacts the upper side wall of the mono frame (210) may be laser welded. That is, the hollow portion may be compressed and deformed, and then the corresponding part may be welded to form a weld (CP). By applying the stepped portion (210a, 230a), the welding area can be increased, and accordingly, the bonding strength resulting from the welding can be increased. Since appropriate rigidity can be secured even when using a thin-thickness mono frame (210), a battery module (90) with increased product yield and improved energy density can be provided.

[0071] The width (W) of the stepped portion (230a) of the end frame (230) may be greater than the upper thickness (L) of the side wall of the mono frame (210). Accordingly, durability against external forces may be enhanced, and effects such as blocking internal penetration of the laser beam during laser welding may be achieved. If the laser beam passes through the side wall of the mono frame (210) and penetrates into the interior, the cell stack (100) and other internal structures may be damaged. According to the present invention, by appropriately designing the stepped portion (210a, 230a), the penetration of the laser beam into the interior can be blocked, thereby improving the productivity of the battery module (90).

[0072] The combination of the end frame (230) and the mono frame (210) may have a different aspect instead of having a stepped portion (210a, 230a). FIG. 7 is an enlarged view of portion C of FIG. 2.

[0073] In this embodiment, the end frame (230) includes a projection (232) that is inserted into the hollow portion (224) of the mono frame (210). The projection (232) may have a shape corresponding to the hollow portion (224). For example, if the hollow portion (224) has a rectangular cross-section, the projection (232) may be in the shape of a rectangular prism. As another example, if the hollow portion (224) has a circular cross-section, the projection (232) may be in the shape of a cylinder. The projection (232) is inserted into each hollow portion (224), and the surface of the end frame (230) that abuts the mono frame (210) may be laser welded. The mono frame (210) has a hollow portion (224). To supplement the thickness of the wall around the hollow section (224), a protrusion (232) is added to the weld of the end frame (230), and the protrusion (232) is matched to the hollow section (224) to secure welding strength. The hollow section (224), which is open at both ends and included in the monoframe (210), may have both ends closed by the end frame (230). Therefore, an insulating air layer is maintained in the hollow section (224), and the intrusion of foreign matter into the hollow section (224) from the outside can be blocked.

[0074] Figure 8 is another enlarged view of part E of Figure 4.

[0075] According to another aspect of the present invention, the surface of the metal hollow material may further include a ceramic coating layer (226) composed solely of an inorganic material without organic material. The ceramic coating layer (226) may be formed on only one surface of the metal hollow material, for example, the outer side, or on both surfaces, for example, both the outer and inner sides.

[0076] The ceramic coating layer (226) is a fire-resistant coating. Conventional ceramic coatings involve coating an organic material (e.g., fluoropolymer) with ceramic as a partial additive. In the present invention, a ceramic coating layer (226) is used that is environmentally friendly and high-performance because it is free of organic materials and ceramic is the main raw material. The ceramic coating layer (226) can be formed by applying a coating agent containing ceramic powder and curing it naturally or at a low temperature of around 200°C. In other words, the outer wall or inner wall of the module case (200) of the battery module (90) of the present invention further includes a fire-resistant coating layer, and this fire-resistant coating layer is an environmentally friendly ceramic coating layer (226) that has been applied and cured.

[0077] The coating agent may be a slurry formed by mixing fine ceramic powder, such as alumina or silica, with water and an inorganic dispersant. It may also include inorganic oxides (such as K2O or BaO) that enable the formation of a glassy substance. However, this slurry does not contain organic solvents or organic binders. If organic solvents or organic binders are included, the heat resistance is low, and the coating deteriorates over time after formation. In the present invention, a ceramic coating layer (226) can be formed by applying and curing such a slurry-type coating agent on the surface of a hollow metal material. The application may be performed using any method, such as dip coating, spin coating, spray coating, or brushing. This slurry-type coating agent enables low-temperature fusion by directly coating the metal, is environmentally friendly and harmless to the human body, and has excellent corrosion resistance, wear resistance, and adhesion.

[0078] The ceramic coating layer (226) can block flames of 1000°C or higher. Accordingly, it can block the propagation of flames to adjacent battery modules. In addition, the ceramic coating layer (226) can further improve the durability of the battery module (90).

[0079] Meanwhile, the battery pack and automobile according to the present invention include a battery module according to the present invention as described above.

[0080] FIG. 9 is a schematic drawing illustrating a battery pack according to one embodiment of the present invention. FIG. 10 is a schematic drawing illustrating an automobile according to one embodiment of the present invention.

[0081] The battery module (90) and the battery pack (300) containing the above-described module can be applied to various devices. Typical examples of such devices include means of transportation such as electric bicycles, electric vehicles, and hybrid vehicles, but the present invention is not limited thereto. The battery pack (300) is suitable for use as a battery pack for electric vehicles. Additionally, it may be used as an energy source for a power storage device (ESS).

[0082] Referring to FIGS. 9 and FIGS. 10, the battery pack (300) may include at least one battery module (90) according to the preceding embodiment and a pack case (310) for packaging the at least one battery module (90).

[0083] The battery pack (300) according to the present invention may further include various devices for controlling the charging and discharging of the battery module (90), such as a Battery Management System (BMS), a current sensor, a fuse, etc., in addition to the battery module (90) and the pack case (310). The BMS estimates the state of the cells within the battery pack (300) and manages the battery pack (300) using the estimated state information. For example, it estimates and manages state information of the battery pack (300), such as the State of Charge (SOC), State of Health (SOH), maximum allowable input / output power, and output voltage of the battery pack (300). Furthermore, it controls the charging or discharging of the battery pack (300) using this state information, and it is also possible to estimate the replacement time of the battery pack (300).

[0084] The battery modules (90) are formed in a nearly rectangular shape and can be arranged neatly inside the battery pack case (310), and each battery module (90) is connected to secure power necessary for driving the vehicle (400).

[0085] The battery pack case (310) is a container for securely storing battery modules (90) and is a rectangular box. The battery pack case (310) can be disposed at a predetermined location within the vehicle (400).

[0086] Preferably, the vehicle (400) may be an electric vehicle. The battery pack (300) may be used as an electric energy source to drive the vehicle (400) by providing driving force to the motor of the electric vehicle. In this case, the battery pack (300) has a high nominal voltage of 100V or more.

[0087] The battery pack (300) may be charged or discharged by an inverter depending on the operation of the motor and / or internal combustion engine. The battery pack (300) may be charged by a regenerative charging device combined with a brake. The battery pack (300) may be electrically connected to the motor of the vehicle (400) through the inverter. In addition, it is obvious that the battery pack (300) may also be equipped in other devices, mechanisms, and facilities, such as a power storage device (ESS) using a secondary battery, in addition to the vehicle.

[0088] As such, devices, mechanisms, and facilities equipped with the battery pack (300), such as the battery pack (300) and the automobile (400) according to the present embodiment, include the aforementioned battery module (90), and thus can implement a battery pack (300) having all the advantages of the aforementioned battery module (90) and devices, mechanisms, and facilities such as the automobile (400) equipped with such a battery pack (300).

[0089] Meanwhile, although terms indicating directions such as up, down, front, and back have been used in this specification, these terms are for convenience of explanation only and may vary depending on the position of the object or the position of the observer, as is obvious to those skilled in the art to which this invention belongs.

[0090] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific preferred embodiments described above. It is understood that anyone skilled in the art can make various modifications without departing from the essence of the invention as claimed in the claims, and such modifications will be within the scope of the claims. Explanation of the symbols

[0091] 90: Battery module 100: Cell stack 110: Cell 111: Cell case 111a: Receiving section 111b: Sealing section 112: Electrode lead 113: Sealing tape 200: Modular Case 210: Mono Frame 210a, 230a: Step section 222: Metal plate 224: Hollow Part 230: End Frame 232: Protrusion 240: Busbar frame CP: Weldment 300: Battery Pack 400: Car

Claims

Claim 1 A battery module comprising: a cell stack having a plurality of cells stacked thereon; a rectangular tubular monoframe having openings that are open on both sides and housing the cell stack; and an end frame coupled to the openings at the front and rear of the cell stack; wherein the monoframe is made of a metal hollow material having a plurality of hollow portions that are open at both ends and are isolated from each other, extending along the extension direction of the monoframe within a metal plate. Claim 2 A battery module according to claim 1, wherein the cell stack comprises a plurality of cells including electrode leads on at least one side in the longitudinal direction stacked face-to-face, the monoframe surrounds the upper surface, lower surface, and both sides of the cell stack where the electrode leads are not formed, and the end frame is positioned to face the electrode leads of the cell stack. Claim 3 A battery module according to paragraph 2, wherein the hollow portion extends along the length direction. Claim 4 A battery module according to claim 1, characterized in that the hollow portion in the metal hollow material is included as a single layer. Claim 5 A battery module according to claim 4, characterized in that the height of the hollow portion in the metal hollow material is 0.3-2mm, the thickness of the metal layer above the hollow portion and the thickness of the metal layer below the hollow portion are 0.3-1mm, and the spacing between the hollow portions is 0.3-2mm. Claim 6 A battery module according to claim 1, characterized in that it includes a stepped portion having a relatively thinner thickness than other parts on the outer periphery of the opening side of the monoframe and on the outer periphery of the endframe. Claim 7 A battery module according to claim 6, characterized in that the outer surface of the opening side of the monoframe and the outer surface of the endframe are flat, and the stepped portion is formed by an inner depression. Claim 8 A battery module characterized in that, in claim 6, the stepped portion of the monoframe is a structure that compresses the hollow portion. Claim 9 A battery module according to claim 8, characterized in that the stepped portion is 0.3-2 mm thinner than other portions. Claim 10 A battery module according to claim 6, wherein the stepped portion of the end frame is formed by cutting the outer periphery of the end frame at a right angle. Claim 11 A battery module characterized in that, in claim 6, the stepped portion of the end frame is seated on the stepped portion of the mono frame. Claim 12 A battery module characterized in that, in claim 6, the width of the stepped portion of the end frame is greater than the thickness of the upper side wall of the mono frame. Claim 13 A battery module according to claim 6, characterized in that the stepped portion of the end frame abuts the upper side wall of the mono frame is laser welded. Claim 14 A battery module according to claim 1, wherein the end frame includes a projection inserted into the hollow portion. Claim 15 A battery module according to claim 14, characterized in that the above-mentioned protrusions are inserted into each of the above-mentioned hollow portions and the surface of the end frame that abuts the monoframe is laser welded. Claim 16 A battery module according to claim 1, characterized in that an insulating air layer is formed by the hollow portion. Claim 17 A battery module according to claim 1, characterized in that the metal hollow material is manufactured by extrusion. Claim 18 A battery module according to claim 1, further comprising a ceramic coating layer made entirely of inorganic material without organic material on the surface of the metal hollow material. Claim 19 A battery pack comprising a battery module according to any one of claims 1 to 18. Claim 20 An automobile comprising a battery module according to any one of paragraphs 1 through 18.

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