Module frame for secondary battery and secondary battery including same

Abstract

A module frame for a secondary battery according to various embodiments may be configured to accommodate a battery cell stack including a plurality of battery cells stacked in one direction, in which the module frame is formed from a composite material-based plate including a fiber-reinforced plastic; and the plate includes at least a plurality of layers including a first layer and a second layer, and has a layered cross-section symmetrical in a thickness direction of the plate. In addition, other embodiments are also possible.

Description

Technical Field

[0001] The present disclosure relates to a module frame for a secondary battery and a secondary battery including the module frame. Background Art

[0002] In modern society, the use of various portable devices, such as mobile phones, laptop computers, and digital cameras, has become widespread. Consequently, the development of battery-related technologies, which are essential components of various mobile devices, is actively underway. Furthermore, electric vehicles, which use electricity as a power source, are becoming an alternative to internal combustion engine vehicles, which have caused various problems, such as environmental pollution. In line with this trend, the demand for the development of secondary batteries installed in electric vehicles is increasing.

[0003] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these batteries, lithium secondary batteries have attracted much attention because, compared with other nickel-based secondary batteries, lithium secondary batteries have the advantages of free charge and discharge, extremely low self-discharge rate, high energy density, and almost no memory effect.

[0004] In these lithium secondary batteries, lithium oxide and carbon materials can be mainly used as positive electrode active materials and negative electrode active materials, respectively. A lithium secondary battery may include: an electrode assembly, which is composed of a positive electrode plate and a negative electrode plate, and a separator placed between the positive electrode plate and the negative electrode plate, each of which is coated with a positive electrode active material and a negative electrode active material, respectively; and a battery case, which seals and stores the electrode assembly together with the electrolyte.

[0005] Generally, lithium secondary batteries may be classified into can-type secondary batteries in which an electrode assembly is accommodated in a metal can and pouch-type secondary batteries in which an electrode assembly is accommodated in a pouch made of an aluminum laminate, according to the shape of an outer packaging material.

[0006] For secondary batteries used in small devices, it is sufficient to consist of only two to three battery cells. However, secondary batteries used in medium and large devices such as automobiles may need to be implemented in the form of battery modules that electrically connect multiple battery cells to increase capacity and output. The battery module can be installed inside the module frame for the secondary battery in the form of a battery cell laminate in which multiple battery cells are connected in series or in parallel to each other. In addition, one or more battery modules can be installed together with various control and protection systems such as a battery management system (BMS) and a cooling system to form a battery pack.

[0007] In this way, the module frame of the secondary battery on which the battery cell laminate is mounted can function as an outer casing that provides mechanical support to battery cells lacking mechanical rigidity and protects the battery cells from external impacts and the like.

[0008] The module frame of the secondary battery may be manufactured in various shapes according to the module shape and structure of the secondary battery. In an example embodiment, the module frame of the secondary battery may be manufactured in a square tube shape called a single frame (see FIG. Figure 1b and Figure 1c ) or U-shaped frame (see Figure 1d ).

[0009] Furthermore, a module frame of a secondary battery is generally made mainly of a metal material (eg, aluminum alloy) to protect the battery cell laminate from external impact or to facilitate storage. Summary of the Invention

[0010] Technical Purpose

[0011] However, when using metal materials to manufacture module frames for secondary batteries, there are limitations on reducing the weight of the secondary battery due to its material properties, and the module frame manufacturing methods are also restricted. Even during product development, the limited use of a uniform material makes it difficult to differentiate and diversify products. Furthermore, with the trend of increasing secondary battery capacity, there is a growing need to develop module frames with the stress tolerance to withstand the expansion of battery cells.

[0012] According to various exemplary embodiments of the present disclosure, a module frame and a secondary battery including the same are provided, which are lighter than existing models and have characteristics optimized for secondary batteries by utilizing a composite material including a fiber reinforced plastic (FRP) material and a metal plate.

[0013] Technical Solution

[0014] According to various example embodiments of the present disclosure, a module housing for a secondary battery is provided, wherein the module housing for the secondary battery is used to accommodate a battery cell laminate including a plurality of battery cells laminated along a first direction, wherein the module housing for the secondary battery is formed by a plate based on a composite material including fiber-reinforced plastic, the plate including: a plurality of first layers, the plurality of first layers being formed of a fiber-reinforced plastic material having electrical insulating properties; and at least one second layer, the at least one second layer being formed of a material different from the plurality of first layers and being interposed between the plurality of first layers, and the plate including a layered cross-sectional structure that is symmetrical in a thickness direction of the plate.

[0015] According to one example embodiment, a plurality of second layers may be prepared, and the board may include a third layer formed of a material different from the plurality of first layers and the plurality of second layers and interposed between the second layers.

[0016] According to an example embodiment, each of the plurality of first layers, each of the plurality of second layers, and the third layer may each include a plurality of fine layers, the number of which is the same for each of the plurality of first layers, each of the plurality of second layers, and the third layer.

[0017] According to an example embodiment, each of the plurality of first layers, each of the plurality of second layers, and the third layer may each include a plurality of subdivided layers including a layered cross-sectional structure that is symmetrical in a thickness direction.

[0018] According to an example embodiment, the at least one second layer may include: at least one first subdivided fiber layer, the at least one first subdivided fiber layer being composed of filaments arranged so that the direction corresponding to the main stress direction of the plate is the length direction of the thread; and at least one second subdivided fiber layer being composed of filaments arranged so that the direction corresponding to the direction other than the main stress direction is the length direction of the thread, wherein the number of the at least one first subdivided fiber layer of the at least one second layer is greater than the number of the at least one second subdivided fiber layer.

[0019] According to an example embodiment, the at least one second subdivided fiber layer of the at least one second layer may consist of filaments arranged such that a direction corresponding to the secondary stress direction of the panel is a length direction of the filaments.

[0020] According to an example embodiment, the primary stress direction and the secondary stress direction may be perpendicular to each other.

[0021] According to an example embodiment, the at least one first subdivided fiber layer of the at least one second layer may include carbon fibers or glass fibers having a density greater than that of the strands constituting the at least one second subdivided fiber layer of the at least one second layer.

[0022] According to one example embodiment, the third layer may include at least one of a finely divided layer composed of basalt fibers and a finely divided layer composed of a metal sheet made of stainless steel.

[0023] According to one example embodiment, each of the plurality of second layers and the third layer may have substantially the same thickness.

[0024] According to an example embodiment, the third layer may include: at least one first subdivided layer, which is formed by filaments arranged so that the direction corresponding to the main stress direction of the plate is the length direction of the filament; and at least one second subdivided layer, which is formed by filaments arranged so that the direction corresponding to the secondary stress direction of the plate is the length direction of the filament, wherein the number of the at least one first subdivided layer of the third layer may be less than the number of the at least one second subdivided layer of the third layer.

[0025] According to one example embodiment, the module case for a secondary battery may further include a mounting flange on a closed end portion of the side surface, and the mounting flange may be formed of the same material as that of the plate.

[0026] According to one example embodiment, a module case for a secondary battery may be manufactured by a resin transfer molding (RTM) method, a heterogeneous injection molding method, a pressing method, or a drawing method.

[0027] According to one example embodiment, each of the plurality of first layers may have a thickness of less than 2 mm. Alternatively, each of the plurality of first layers may have a thickness corresponding to approximately half the thickness of the third layer.

[0028] According to various example embodiments of the present disclosure, there is provided a module housing for a secondary battery, the module housing for the secondary battery being used to accommodate a battery cell laminate including a plurality of battery cells laminated along a first direction, wherein the module housing for the secondary battery is formed by a plate based on a composite material including fiber reinforced plastic, the plate including: a third layer arranged at the center based on a cross-section of the plate in a thickness direction; a plurality of first layers arranged on an outer surface based on a cross-section of the plate in a thickness direction; and a plurality of second layers arranged on both sides with the third layer therebetween and interposed between the plurality of first layers, wherein the plurality of first layers are formed of a fiber reinforced plastic material having electrical insulating properties, the plurality of second layers have higher mechanical strength than the plurality of first layers, and the third layer includes at least one of basalt fiber and a metal sheet.

[0029] Beneficial effects

[0030] According to example embodiments, a module frame for a secondary battery and a secondary battery including the module frame may be configured to have weight performance, mechanical strength (e.g., tensile strength) performance, stiffness performance, insulation performance, fire resistance performance, and / or manufacturing cost performance optimized for various types of secondary batteries by using FRP materials.

[0031] According to example embodiments, by making a composite material-based plate including an FRP material for forming a module frame have a layered cross-sectional structure symmetrical in a thickness direction, unnecessary manufacturing processes may be omitted and durability problems at specific points in the module frame may be prevented.

[0032] By the module frame having improved fire resistance, even when a thermal event occurs in the secondary battery, the structural collapse of the secondary battery module itself can be prevented, or heat diffusion can be prevented by blocking the inflow of oxygen.

[0033] Furthermore, by designing the module frame in consideration of the primary stress directions that the secondary battery module must withstand, such as expansion of the battery cells, a secondary battery with maximum structural stability can be provided. Furthermore, a module frame configured to withstand greater internal pressure than existing module frames can be provided.

[0034] However, the present disclosure is not limited to the above-described aspects, and it is apparent that undescribed aspects can be clearly understood by those skilled in the art from this specification and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1a is a schematic exploded perspective view of a secondary battery module according to an example embodiment of the present disclosure.

[0036] Figure 1b to Figure 1d is a perspective view of a module frame for a secondary battery according to various example embodiments of the present disclosure.

[0037] Figure 2 is a cross-sectional view schematically illustrating a layered cross-sectional structure of plates constituting a module frame according to various example embodiments of the present disclosure.

[0038] Figure 3 is a schematic perspective view illustrating a primary stress direction and a secondary stress direction of a secondary battery module in a module frame according to various example embodiments of the present disclosure.

[0039] Figure 4a Schematic diagram showing the arrangement direction of radial fibers in each of the plurality of fiber layers constituting the first layer.

[0040] Figure 4b Schematic diagram showing the arrangement direction of the original fibers in each of the plurality of fiber layers constituting the second layer.

[0041] Figure 5a and Figure 5b are schematic cross-sectional and perspective views of a module frame for explaining a primary stress direction and a secondary stress direction of the module frame according to various example embodiments of the present disclosure, showing a battery cell expansion phenomenon.

[0042] Figure 6a and Figure 6b are schematic cross-sectional views and perspective views of a module frame for explaining a primary stress direction and a secondary stress direction of the module frame as internal pressure of a secondary battery module increases according to various example embodiments of the present disclosure. DETAILED DESCRIPTION

[0043] Before describing the present disclosure in detail, the terms or words used in the specification and claims should not be interpreted as being limited to their common meanings or dictionary meanings. In addition, the terms or words should be interpreted with meanings and concepts consistent with the technical ideas of the present disclosure based on the principle that the inventor can appropriately define the term concepts in order to explain his or her invention in the best way. The example embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present disclosure and do not necessarily represent the entire technical ideas of the present disclosure. Therefore, at the time of filing this disclosure, various equivalents and modifications that can replace them may exist.

[0044] The same reference numerals or symbols shown in each of the drawings attached to the specification may represent parts or components that perform substantially the same function. For ease of description and understanding, the same reference numerals or symbols may be used to describe different embodiments. In other words, even if components or elements with the same reference numerals are shown in multiple drawings, the multiple drawings may not all represent a single example embodiment.

[0045] In the following description, unless the context clearly indicates otherwise, singular expressions include plural expressions. It will be understood that when an element (e.g., a first element) is "coupled (operably or communicatively) to another element (e.g., a second element)" or "connected" or "coupled (operably or communicatively) to another element", the element may be directly coupled to the other element or directly coupled to the other element, and an intermediate element (e.g., a third element) may exist between the element and the other element. The terms "having", "can have", "including" and "can include" as used herein represent the presence of corresponding features (e.g., elements such as numerical values, functions, operations or components), and do not exclude the presence of other features.

[0046] In addition, in the following description, expressions such as upper side, top, lower side, bottom, side, front side, and rear side are expressed based on the directions shown in the drawings. If the direction of the object is changed, it may be expressed in a different way.

[0047] Additionally, in the specification and claims, terms including ordinal numbers such as "first," "second," and the like may be used to distinguish components or elements. These ordinal numbers are used to distinguish identical or similar components from one another, and the meanings of these terms should not be construed in a limited manner due to the use of such ordinal numbers. For example, components or elements incorporating these ordinal numbers should not be construed as having a limited order or arrangement of use based on the numbers. Each ordinal number can be used interchangeably, if desired.

[0048] Hereinafter, example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the spirit of the present disclosure may not be limited to the example embodiments. For example, those skilled in the art who understand the spirit of the present disclosure may suggest other example embodiments that fall within the spirit of the present disclosure by adding, modifying, or deleting components or elements; however, these example embodiments are intended to be included within the scope of the present disclosure. For clarity of explanation, the shapes and sizes of elements in the drawings may be exaggerated.

[0049] Figure 1a is a schematic exploded perspective view of a secondary battery module 100 according to an example embodiment of the present disclosure. Figure 1b to Figure 1d is a perspective view of a module frame 130 for a secondary battery according to various example embodiments of the present disclosure.

[0050] Reference Figures 1a to 1d The secondary battery module 100 according to various example embodiments may include a battery cell laminate including a plurality of battery cells 110 and a case assembly accommodating the battery cell laminate. The case assembly is intended to physically protect the battery cell laminate and is configured to have desired mechanical strength and rigidity characteristics.

[0051] The housing assembly may include a module frame 130 (see Figure 1b to Figure 1d ) and cover assemblies (first cover assembly 121 and second cover assembly 122).

[0052] For example, the shell assembly may include a module frame 130, a first cover assembly 121 covering a first side surface (e.g., a front side, an end facing the +y direction) of an open end of the module frame 130, and a second cover assembly 122 covering a second side surface (e.g., a rear side, an end facing the -y direction) of another open end of the above-mentioned module frame.

[0053] The module frame 130 may have Figure 1b and Figure 1c Single frame structure as shown or Figure 1d In addition, when the module frame 130 has a U-shaped structure as shown in FIG. Figure 1dWhen the structure shown includes a U-shaped frame, as a shell component, it can also include a third cover component (not shown) covering a third side surface (for example, an end facing the top surface and the +z direction) which is the other open end of the above-mentioned U-shaped frame.

[0054] At least a portion of such a housing assembly may be formed of substantially the same material as the module frame 130 (eg, FRP material), or may be formed of a simple metal material (eg, aluminum alloy).

[0055] In example embodiments, the battery cell 110 may include a pouch-type battery cell.

[0056] A pouch-type battery cell can be formed by placing an electrode shell in a pouch-type casing made of a laminate including a resin layer and a metal layer, and then heat-fusing the sealing portion of the pouch-type casing. Here, the battery cell 110 may have a generally rectangular sheet structure. However, the battery cell 110 included in the secondary battery module is not limited to a pouch-type battery cell. For example, the battery cell 110 may consist of a square battery cell in which an electrode assembly is housed inside a square casing having a predetermined rigidity, or may be configured as a cylindrical battery cell in which an electrode assembly is housed inside a cylindrical casing.

[0057] A plurality of battery cells 110 may be prepared to form a battery cell laminate.

[0058] For example, the plurality of battery cells 110 constituting the battery cell laminate may be electrically interconnected and arranged in substantially parallel stacks along one direction (eg, +x direction), which may be perpendicular to the direction in which gravity acts.

[0059] The module frame 130 according to various example embodiments may be as follows Figure 1b As shown, the flange 131 is included on at least one side (e.g., the closed surface of the two side surfaces), and Figure 1c The flange 131 may not be included as shown.

[0060] Furthermore, in an example embodiment, when the module frame 130 includes the flange 131, the flange 131 may be formed based on a material substantially the same as that of the plate 200 constituting each surface of the module frame 130 (e.g., the upper surface, the lower surface, and the closed surface of both side surfaces) (e.g., a composite material including at least one of FRP and a metal sheet).

[0061] According to various exemplary embodiments of the present disclosure, the module frame 130 may be formed of a plate 200 based on a composite material including an FRP material, a metal sheet, or the like.

[0062] FRP can include a reinforcement whose stiffness is determined by a fiber material, and a matrix resin that transmits stress to the reinforcement and maintains the shape of the reinforcement or composite material. The matrix resin can be viscous and can be embedded within at least one fiber layer of the reinforcement or between fiber layers, and then the matrix resin can be cured to form at least one fiber layer.

[0063] For example, the fiber material may include at least one of glass fiber, carbon fiber, basalt fiber, polymer fiber (eg, Kevlar fiber, nylon, polyester, and aramid), ceramic fiber, and boron fiber.

[0064] The matrix resin may include at least one thermosetting resin material such as polyurethane and epoxy resin.

[0065] Furthermore, in example embodiments, the composite material may further include a sheet material (eg, at least one of a polyethylene terephthalate (PET) sheet, a polyurethane (PU) sheet, or a metal (eg, stainless steel) sheet) interposed between the fiber materials.

[0066] Figure 2 is a cross-sectional view schematically illustrating a layered cross-sectional structure of plates constituting each side of the module frame 130 according to various exemplary embodiments of the present disclosure.

[0067] Reference Figure 2 , the plate 200 forming the module frame 130 may include multiple layers (e.g., a first layer 220, a second layer 240, and a third layer 260) with different properties. In particular, the plate 200 according to various example embodiments of the present disclosure may have a layered structure that is symmetrical in the thickness direction. In other words, the single-layer structure of the plate 200 when facing the outside from the inside of the module (e.g., the secondary battery module 100 of FIG. 1 ) and the single-layer structure when facing the inside from the outside of the module may be identical to each other in at least one of material, thickness, and precursor arrangement. The plate 200 having such a symmetrical layered cross-sectional structure does not need to distinguish between the two sides, and therefore can have advantages in the manufacturing process. In addition, using the plate 200, local stiffness differences on each side of the manufactured module can be prevented.

[0068] Specifically, the first layer 220 corresponding to the outermost layer of the board 200 (eg, a layer positioned at the outermost side and a layer positioned at the innermost side of the secondary battery module) may be configured to have electrical insulation properties.

[0069] For example, the first layer 220 may include FRP having non-conductor properties (insulating properties), such as glass fiber, basalt fiber, and aramid fiber.

[0070] Specifically, in an exemplary embodiment, the first layer 220 may include a plurality of subdivided fiber layers. Here, the subdivided fiber layers may be arranged such that the arrangement directions of the raw fibers constituting each subdivided fiber layer are combined with each other to form an overall radial structure.

[0071] The first layer 220 is placed on the outside of the plate 200, so it may need to be protected the most from external physical forces. In addition, in addition to external physical forces, it may also need to withstand the internal pressure generated within the frame of the secondary battery module. Therefore, when each subdivided fiber layer is configured so that each first layer 220 (e.g., layer 1-1 220a and layer 1-2 220b) has an overall radial structure, regardless of the direction of the external force acting on the plate 200, the possibility of damage to the plate 200 in each direction can be minimized.

[0072] Furthermore, in the example embodiment, when the principal stress direction of the secondary battery module (e.g., the secondary battery module 100 in FIG. 1 ) (in other words, under a normal use environment of the secondary battery module, the first direction corresponds to a direction in which the stress ratio acting on the module frame 130 is the highest) (e.g., Figure 3 and Figure 4a ) and a secondary stress direction of the secondary battery module (in other words, a second direction corresponding to the second highest stress applied to the module frame 130 under a normal use environment of the secondary battery module) (e.g., a direction perpendicular to the first direction within a plane parallel to each plate 200 of the module frame 130, e.g., Figure 3 and Figure 4a When the directions shown by the arrows "2" in the figure are set to two axes of 0 degrees and 90 degrees respectively, the first layer 220 can be configured to have the following arrangement, wherein one direction of "0 degrees" (-180 degrees) (i.e., the main stress direction of the module), "90 degrees" (-90 degrees) (i.e., the secondary stress direction of the module), "45 degrees" (-135 degrees) and "135 degrees" (-45 degrees) is the length direction of the raw fibers of each subdivided fiber layer, and each subdivided fiber layer (e.g., layer 1-1 220a or layer 1-2 220b) is laminated to form a fiber layer having a radial structure. In addition, it is also obvious that based on the direction in which the battery cells 110 are arranged inside the module frame 130, the main stress direction of the secondary battery module can be Figure 3 and Figure 4a In the direction other than the direction of arrow "1" shown in FIG. Figure 3 and Figure 4a direction indicated by arrow “2”).

[0073] Furthermore, according to various example embodiments of the present disclosure, the module frame 130 may be configured to have the same symmetrical structure when viewed from the inside or outside of the secondary battery module based on the layered cross-section of the plate 200 .

[0074] For example, based on the inside-to-outside direction or the outside-to-inside direction of a particular panel 200, when layer 1-1 220a (the outermost layer of panel 200) is formed by laminating in order a first subdivided fiber layer arranged so that the "0 degree" (-180 degree) direction (i.e., the principal stress direction of the module) is the length direction of the filament, a second subdivided fiber layer arranged so that the "45 degree" (-135 degree) direction is the length direction of the filament, and a third subdivided fiber layer arranged so that the "135 degree" (-45 degree) direction is the length direction of the filament, the corresponding layer 1-2 220b (the innermost layer of panel 200) is formed so that the third subdivided fiber layer, the second subdivided fiber layer and the first subdivided fiber layer are laminated in sequence, thereby achieving a symmetrical structure of panel 200.

[0075] Furthermore, the first layer 220 may be configured to include, in addition to the aforementioned "0 degree," "90 degree," "45 degree," and "135 degree" orientations, subdivided fiber layers arranged in a radial configuration oriented at "30 degrees" (-150 degrees) or "60 degrees" (-120 degrees). In addition, various other forms of radial configurations not mentioned above are contemplated. By way of example, in the module frame 130, stress acting on the first layer 220 of each panel 200 may be distributed in multiple directions to ensure structural stability.

[0076] Furthermore, when the module frame 130 is manufactured using metal as in the prior art, at least some surfaces facing the battery cells 110 (or the battery cell laminate) must be insulated, or the insulated coating must be performed directly on the outer surfaces of the battery cells 110 (or the battery cell laminate). However, according to some exemplary embodiments of the present disclosure, each outermost layer of the plate 200 in the module frame 130 may have insulating properties, and thus the insulated coating of the outer surfaces of the module frame 130 or the outer surfaces of the battery cells 110 may be omitted.

[0077] In addition, the second layer 240 is a layer inserted between the first layer 220 corresponding to the outermost layer of the plate 200 and the third layer 260 corresponding to the central layer of the plate 200, and the second layer 230 can correspond to a layer having better mechanical strength properties (e.g., tensile strength) or stiffness properties than other layers.

[0078] In an exemplary embodiment, the first layer 220 and the second layer 240 may vary based on the number of fiber bundles comprising each layer. The difference between the first layer 220 and the second layer 240 may be based on a difference in target strength or stiffness. For example, the stiffness of the first layer 220 may be less than or equal to that of an aluminum alloy, while the stiffness of the second layer 240 may be greater than that of an aluminum alloy.

[0079] In example embodiments, the second layer 240 may be defined as a layer arranged to align with a principal stress direction (eg, Figure 3 The number of strands arranged in the first direction (the aforementioned 0-degree direction) corresponding to the direction indicated by the arrow "1" in the figure) along the strand's length is greater than the number of strands (or the number of subdivided fiber layers) arranged in any other direction. Therefore, in second layer 240, mechanical strength in the module's principal stress direction can be ensured. For example, the number of strands (or the number of subdivided fiber layers) corresponding to the principal stress direction can have a ratio of approximately 50% or greater to the total number of strands (or the total number of subdivided fiber layers) in second layer 240.

[0080] For example, the second layer 240 may include at least one of glass fiber, carbon fiber, basalt fiber, and aramid fiber. For example, in an exemplary embodiment, the second layer 240 may include at least one subdivided fiber layer composed of carbon fibers, the carbon fibers being arranged such that the first direction (i.e., the principal stress direction of the secondary battery module 100) is the length direction of the carbon fiber precursors.

[0081] However, the present disclosure is not limited to the exemplary embodiments. For example, in another exemplary embodiment, the second layer 240 may not include a subdivided fiber layer composed of carbon fibers. Instead, the second layer 240 may be configured such that the subdivided fiber layer composed of glass fibers arranged such that the first direction is the length direction of the precursors has a higher precursor density than the subdivided fiber layer of another layer (e.g., the subdivided fiber layer composed of glass fibers of the first layer 220). In this case, the second layer 240 can be formed with a certain level of rigidity without using expensive carbon fibers.

[0082] In an exemplary embodiment, the second layer 240 , like the first layer 220 , may also include a plurality of subdivided fiber layers.

[0083] For example, the second layer 240 may include a plurality of layers having a plurality of filaments along a first direction (eg, Figure 3 and Figure 4b The second layer 240 may further comprise a subdivided fiber layer having filaments arranged in a direction (indicated by arrow "1" in the figure), the first direction being the main stress direction of the module. In addition, the second layer 240 may further comprise a layer of filaments arranged in a direction facing the secondary stress direction of the module (i.e., a second direction perpendicular to the first direction in the plane of the plate 200) (e.g., Figure 3 and Figure 4b For example, when the second layer 240 includes subdivided fiber layers in which the filaments are arranged to face the secondary stress direction, the number of subdivided fiber layers corresponding to the secondary stress direction may be less than or equal to the number of subdivided fiber layers corresponding to the primary stress direction.

[0084] Furthermore, even in the case of the second layer 240, based on the third layer 260 as the central layer of the board 200, each subdivided fiber layer can be formed so that the layer 2-1 240a located on the top and the layer 2-2 240b located on the bottom are symmetrical to each other in terms of material, thickness, and filament arrangement.

[0085] In addition, as a layer placed in the center of the layered cross-sectional structure of the board 200, the third layer 260 may be a layer having enhanced fire resistance compared to the other layers (the first layer 220 and the second layer 240). For example, the third layer 260 may be configured to include a material having a high melting point and low thermal conductivity.

[0086] For example, the third layer 260 may be configured to include at least one of a metal sheet made of basalt fiber or stainless steel.

[0087] Generally, when a module frame 130 for a secondary battery is formed of a composite material including FRP, the module frame 130 may be more susceptible to thermal runaway of the secondary battery than a module frame 130 typically composed solely of a metal material used in the prior art. However, according to various exemplary embodiments of the present disclosure, since the module frame 130 is provided with a third layer 260 having enhanced fire resistance on the central side, the structural collapse of the module frame 130 can be effectively prevented in a high-temperature or high-pressure environment.

[0088] Furthermore, in example embodiments, the third layer 260 may be formed to have a thickness greater than that of the first layer 220 (e.g., layer 1-1 220a or layer 1-2 220b) or the second layer 240 (e.g., layer 2-1 240a or layer 2-2 240b). For example, the third layer 260 may be formed to have a thickness approximately twice that of the first layer (layer 1-1 220a, layer 1-2 220b) or the second layer (layer 2-1 240a, layer 2-2 240b). Conversely, in other example embodiments, each of the layers (e.g., layer 1-1 220a, layer 2-1 240a, third layer 260, layer 2-2 240b, and layer 1-2 220b) may be formed to have substantially the same thickness as one another, or may be configured to include an equal number of subdivided layers (subdivided fiber layers or metal sheet layers corresponding to the subdivided fiber layers). For example, each layer may be configured to include four subdivided layers (or, each layer may include five subdivided layers). In another exemplary embodiment, only the second layer 240 (i.e., layer 2-1 240a and layer 2-2 240b) and the third layer 260 may be configured to have the same thickness and include the same number of subdivided layers, respectively, while the first layer 220 associated with electrical insulation performance (i.e., layer 1-1 220a and layer 1-2 220b) may be configured to have a smaller thickness than the second layer 240 or the third layer 260, or include a smaller number of subdivided layers. For example, each first layer 220 (layer 1-1 220a and layer 1-2 220b) may have a thickness of less than 2 mm, and layers other than the first layer 220 may have a thickness greater than 2 mm.

[0089] Furthermore, in example embodiments, the arrangement direction of the raw fibers constituting the subdivided fiber layer included in the third layer 260 may be aligned with the principal stress direction (eg, Figure 3 The first direction in the stress direction (the direction indicated by the arrow "1") corresponds to the first direction in the stress direction (for example, Figure 3 2 corresponds to the second direction (the direction indicated by the arrow "2") in the secondary battery module 100. In an example embodiment, the number of subdivided fiber layers arranged corresponding to the main stress direction among the subdivided fiber layers included in the third layer 260 may be equal to or less than the number of subdivided fiber layers arranged corresponding to the secondary stress direction. In addition, in another example embodiment, the arrangement direction of the precursors constituting the subdivided fiber layers included in the third layer 260 may be different from the main stress direction or the secondary stress direction of the secondary battery module 100. For example, the subdivided fiber layers included in the third layer 260 may have a radial precursor arrangement.

[0090] In various exemplary embodiments, the third layer 260 may be configured to include a fiber material (basalt fiber) or a metal sheet having excellent fire resistance as described above. However, as long as the third layer 260 includes a material having excellent fire resistance as a finely divided layer (a finely divided fiber layer or a metal sheet layer corresponding to the finely divided fiber layer), the third layer 260 may further include another finely divided fiber layer composed of a material other than the above-mentioned materials (e.g., glass fiber, aramid fiber, carbon fiber, etc.). However, in this case, it is more preferable that the finely divided layer formed of a fiber material having excellent fire resistance is arranged on the outermost layer of the third layer 260 (i.e., the finely divided layer adjacent to the second layer 240 (e.g., layer 2-1 240a and layer 2-2 240b)).

[0091] In various example embodiments, the board 200 may have a layered cross-sectional structure that is overall symmetrical in the thickness direction. In addition, in example embodiments, each of the layers constituting the board 200 (e.g., each of the first layer 220 (i.e., layer 1-1 220a and layer 1-2 220b), the second layer 240 (i.e., layer 2-1 240a and layer 2-2 240b), and the third layer 260) may individually have a layered structure that is symmetrical in the thickness direction of the board 200. Therefore, when each layer (e.g., the first layer 220 (layer 1-1 220a and layer 1-2 220b), the second layer 240 (layer 2-1 240a and layer 2-2 240b), and the third layer 260) has a symmetrical structure with no particular direction in the thickness direction, even when the board 200 is produced by prefabricating each layer in a semi-finished product form and then joining them together, there is no need to consider the vertical direction of each layer, and thus the manufacturing process can be convenient. Furthermore, since the isotropy of each layer is ensured, the structural stability can be further improved, and even if a drawing process or a pressing process described later is applied to the plate 200 , the structural stability can be maintained.

[0092] Furthermore, even in another exemplary embodiment, the plate 200 has a structure in which the arrangement direction of each filament is completely symmetrical in the thickness direction without any particular directionality, and each layer constituting the plate 200 (e.g., the first layer 220 (layer 1-1 220a and layer 1-2 220b), the second layer 240 (layer 2-1 240a and layer 2-2 240b), the third layer 260) has a structure in which the subdivided layers constituting each layer are completely symmetrical in terms of material and thickness in the thickness direction, each layer constituting the plate 200 may also be configured such that the two subdivided layers have symmetrical directions with respect to the principal stress direction in terms of the arrangement of the filaments. For example, when the angular difference between the filament arrangement direction of the innermost subdivided layer within a single layer and the principal stress direction is A°, the angular difference between the filament arrangement direction of the outermost subdivided layer and the principal stress direction may be 180-A°.

[0093] In addition, the module frame 130 according to various exemplary embodiments of the present disclosure may be manufactured by an RTM method, or may be manufactured by at least one of a heterogeneous injection molding method, a pressing method, and a drawing method.

[0094] For example, when the module frame 130 is manufactured by a drawing method, the module frame 130 may be manufactured by bending a single plate 200 based on a composite material including FRP according to various example embodiments of the present disclosure into a T-shape (or U-shape) and then joining it to another plate.

[0095] Furthermore, in another exemplary embodiment, when the side surface of the module frame 130 includes at least one flange 131 (see Figure 1b ), when the module frame 130 is manufactured using the RTM method, the flange 131 may be formed integrally with the main body of the module frame 130, but when the module frame 130 is manufactured using the drawing method, the flange 131 portion made of the material of the plate 200 of the above-mentioned module frame 130 may be formed by bonding the flange 131 portion to the side surface of the main body of the module frame 130 using an adhesive or the like. In this case, in terms of the material and the arrangement direction of the raw wire, the flange 131 may have the same structure as the plate 200 constituting the upper surface or the lower surface of the module frame 130. Furthermore, in the exemplary embodiment, even when the drawing method is used for manufacturing, the main body of the flange 131 and the module frame 130 may be formed integrally.

[0096] Figure 3 1 is a schematic perspective view illustrating a primary stress direction and a secondary stress direction of the secondary battery module 100 in the module frame 130 according to various example embodiments of the present disclosure.

[0097] As mentioned above, in Figure 3 In the figure, the first direction (the direction indicated by arrow “1”) may be the principal stress direction of the secondary battery module 100, the second direction (the direction indicated by arrow “2”) may be the secondary stress direction of the secondary battery module 100, and the third direction (the direction indicated by arrow “3”) may be a direction perpendicular to the first and second directions (for example, the thickness direction of each plate 200 constituting the module frame 130).

[0098] For example, the first direction can correspond to a direction parallel to the circumferential direction of the square tubular or U-shaped body of the module frame 130, and the second direction can correspond to a direction from the first open end (e.g., the front side) to the second open end (e.g., the rear side) of the module frame 130 (e.g., a direction parallel to the direction in which the electrode connector of the battery cell 110 points).

[0099] However, the orientation setting may be applied differently considering the direction in which the battery cells 110 are arranged within the module frame 130 in the secondary battery module 100. Therefore, in another example embodiment, Figure 3 The second direction (the direction indicated by arrow “ 2 ”) in FIG. 1 may be a principal stress direction of the secondary battery module 100 .

[0100] Figure 4a 2 is a diagram exemplarily showing the arrangement direction of radial strands of each subdivided fiber layer constituting the first layer 220 . Figure 4b 2 is a diagram exemplarily showing an arrangement direction (eg, a principal stress direction (first direction) or a secondary stress direction (second direction)) of filaments constituting each subdivided fiber layer of the second layer 240 (or the third layer 260 ).

[0101] For ease of explanation, as mentioned above Figure 2 As mentioned above, Figure 4a and Figure 4b The axis corresponding to “0 degrees” in is the first direction, ie, the main stress direction of the secondary battery module 100 , and the axis corresponding to “90 degrees” is the second direction, ie, the secondary stress direction of the secondary battery module 100 .

[0102] Figure 5a and Figure 5b are schematic cross-sectional views and perspective views of the module frame 30 for explaining a primary stress direction and a secondary stress direction of the module frame 130 for explaining an expansion phenomenon of the battery cell 110 according to various example embodiments of the present disclosure.

[0103] Figure 6a and Figure 6b are schematic cross-sectional views and perspective views of the module frame 130 for explaining a primary stress direction and a secondary stress direction of the module frame 130 as the internal pressure of the secondary battery module 100 increases according to various example embodiments of the present disclosure.

[0104] Reference Figure 5a and Figure 5b The battery cells 110 (or battery cell laminate) housed within the module frame 130 of the secondary battery module 100 may be arranged in rows along one direction (e.g., the x-axis direction, see FIG. 1 , etc.). Furthermore, when the battery cells 110 (or battery cell laminate) expand, the cell volume increases in the direction in which the battery cells 110 are stacked, potentially compressing both side surfaces of the module frame 130 (e.g., the closed surfaces of both side surfaces of the module frame 130). Therefore, the module frame 130 may need to absorb the pressure generated therein to provide support.

[0105] For example, when the battery cell 110 (or the battery cell laminate) expands, the expansion pressure may be applied in a direction perpendicular to the main body of the battery cell 110 (the portion housing the electrode assembly) (e.g., Figure 5a Therefore, on the side surface of the module frame 130, stress may be generated in a direction resisting the expansion pressure.

[0106] Specifically, refer to Figure 5a , the expansion pressure of the battery cell 110 (or the battery cell laminate) may be greatest in each central region in the height direction (eg, z-axis direction) based on the side surface of the module frame 130. Figure 5a and Figure 5b As shown, relatively large tension may be generated on the side surface of the module frame 130 in a direction perpendicular to the stacking direction (x-axis direction) of the battery cells 110 and the length direction (y-axis direction) of the battery cells 110. In other words, due to the expansion of the battery cells 110 (or the battery cell laminate), among the stresses in various directions on the side surface of the module frame 130 (the closed end portion of the side surface of the module frame 130), the stress in the z-axis direction may be relatively large.

[0107] Therefore, in the module frame 130 according to various exemplary embodiments of the present disclosure, the expansion phenomenon can be effectively compensated by setting the z-axis direction (first direction) perpendicular to the y-axis as the main stress direction based on the side surface plane of the module frame 130.

[0108] In addition, when the pouch-type battery cells 110 are stacked along the x-axis direction, since each battery cell 110 has a long shape in the y-axis direction, the module frame 130 can also be subjected to a large force on the side surface (e.g., the end parallel to the yz plane) along the direction parallel to the y-axis.

[0109] Specifically, since in the case of a pouch-type battery cell with a large aspect ratio, the change in cell volume due to expansion may be large at the center of the battery cell 110 based on the y-axis, by setting the y-axis direction (second direction) perpendicular to the main stress direction as the secondary stress direction, and by using a composite material including FRP with a radial filament arrangement structure applied to the module frame 130, the structural deformation of the expansion phenomenon in the module frame 130 according to various example embodiments of the present disclosure can be minimized.

[0110] In addition, refer to Figure 6a and Figure 6b As the internal pressure of the secondary battery module 100 increases, an expansion phenomenon may occur in the module frame 130. Therefore, on the surface of each plate 200 of the module frame 130, a direction from the inside to the outside of the secondary battery module 100 (along the direction from the inside to the outside of the secondary battery module 100) may be formed. Figure 6aInternal pressure is applied in the direction of the solid arrow in FIG.

[0111] According to various exemplary embodiments of the present disclosure, based on the direction of pressure acting on the secondary battery module 100, Figure 5a and Figure 5b The explained direction of the expansion action and the manufacturing method of the module frame 130 including the drawing method may determine the main stress direction and the secondary stress direction, and may determine the strand arrangement direction.

[0112] For example, in an exemplary embodiment of the present disclosure, by extending the first direction (eg, Figure 3 The direction indicated by the arrow "1" in the figure is set as the main stress direction, and the length direction of the main body from the first opening end toward the second opening end of the module frame 130 (for example, Figure 3 ) is set as a secondary stress direction, and by determining the original filament arrangement direction of each fiber layer constituting the plate 200 in response thereto, a module frame 130 that maximizes stiffness in consideration of the application and manufacturing method of the module frame 130 for a secondary battery can be provided. Alternatively, in another example embodiment, the original filament arrangement direction of each fiber layer can be determined by setting another specific direction (e.g., the length direction of the body) as the primary stress direction based on the arrangement direction of the battery cells 110, and by setting yet another specific direction (e.g., a first direction parallel to the circumferential direction of the module frame 130 body) as the secondary stress direction based on the primary stress direction.

[0113] Furthermore, when the module frame 130 is formed from a composite material including FRP, as in various exemplary embodiments of the present disclosure, the tensile strength of the module frame 130 can be equal to or greater than that of a module frame formed using a typical metal material, while the composite material can have a lower Young's modulus than metal. Thus, the module frame 130 can be configured to have high rigidity to cope with the expansion of the battery cells 110 while also having elastic properties that can effectively absorb the expansion. Furthermore, since it is lighter than metal, the secondary battery can be made lighter and its energy density can be increased.

[0114] Furthermore, to meet the needs of various types of secondary batteries, the strength, elasticity, and fire resistance of each material can be adjusted differently. Therefore, compared with the metal-based module frame 130 of the related art, according to the exemplary embodiment of the present disclosure, there is a high degree of design freedom.

[0115] Various embodiments of the present disclosure have been described in detail above. However, it is obvious to those skilled in the art that the scope of the present disclosure is not limited thereto, and that various modifications and variations may be made without departing from the technical spirit of the present disclosure as set forth in the claims. In addition, the above-described exemplary embodiments may be implemented by deleting some elements, and each exemplary embodiment may be implemented in combination with each other.

Claims

1. A module housing for a secondary battery, the module housing for a secondary battery being configured to accommodate a battery cell laminate comprising a plurality of battery cells laminated along a first direction, in, The module case for a secondary battery is formed of a plate based on a composite material including fiber-reinforced plastic, Wherein, the plate comprises: a plurality of first layers formed of a fiber-reinforced plastic material having electrical insulating properties; and at least one second layer formed of a material different from that of the plurality of first layers and interposed between the plurality of first layers, and The plate includes a layered cross-sectional structure that is symmetrical in a thickness direction of the plate.

2. The module housing for a secondary battery according to claim 1, wherein Multiple second layers are prepared, The board includes a third layer formed of a material different from that of the plurality of first layers and the plurality of second layers and interposed between the second layers.

3. The module housing for a secondary battery according to claim 2, wherein Each of the plurality of first layers, each of the plurality of second layers, and the third layer each include: A plurality of subdivision layers, the number of the plurality of subdivision layers being the same for each of the plurality of first layers, each of the plurality of second layers, and the third layer.

4. The module housing for a secondary battery according to claim 2, wherein Each of the plurality of first layers, each of the plurality of second layers, and the third layer each include: A plurality of subdivided layers comprises a layered cross-sectional structure that is symmetrical in the thickness direction.

5. The module housing for a secondary battery according to claim 1, wherein Each of the plurality of first layers comprises a plurality of subdivided fiber layers, and A radial structure is included in which an arrangement direction of the filaments constituting any one of the plurality of subdivided fiber layers corresponds to an arrangement direction of the filaments constituting the remaining subdivided fiber layers.

6. The module housing for a secondary battery according to claim 1, wherein The at least one second layer comprises: at least one first layer of finely divided fibers, said at least one first layer of finely divided fibers being composed of said filaments arranged such that the direction corresponding to the main stress direction of the panel is the length direction of the filaments; and at least one second subdivided fiber layer, said at least one second subdivided fiber layer being composed of said filaments arranged so that the direction corresponding to the direction other than said principal stress direction is the length direction of the filaments, wherein the number of the at least one first subdivided fiber layer of the at least one second layer is greater than the number of the at least one second subdivided fiber layer.

7. The module housing for a secondary battery according to claim 6, wherein The at least one second layer of finely divided fibers of the at least one second layer consists of said filaments arranged such that the direction corresponding to the secondary stress direction of the panel is the length direction of the filaments.

8. The module housing for a secondary battery according to claim 7, wherein The principal stress direction and the secondary stress direction are perpendicular to each other.

9. The module housing for a secondary battery according to claim 6, wherein said at least one first subdivided fiber layer of said at least one second layer comprises carbon fibers, or The glass fibers include a density greater than a density of the strands of the at least one second subdivided fiber layer constituting the at least one second layer.

10. The module case for a secondary battery according to claim 2, wherein The third layer includes at least one of a finely divided layer composed of basalt fibers and a finely divided layer composed of a metal sheet made of stainless steel.

11. The module housing for a secondary battery according to claim 2, wherein Each of the plurality of second layers and the third layer have substantially the same thickness.

12. The module housing for a secondary battery according to claim 2, wherein The third layer includes: at least one first subdivided layer formed by the filaments arranged such that the direction corresponding to the main stress direction of the plate is the length direction of the filaments; and at least one second subdivided layer formed by said filaments arranged such that the direction corresponding to the secondary stress direction of the plate is the length direction of the filaments, The number of the at least one first subdivision layer of the third layer is less than the number of the at least one second subdivision layer of the third layer.

13. The module case for a secondary battery according to claim 1, further comprising a mounting flange located on a closed end portion of a side surface, in, The mounting flange is formed from the same material as the plate. 14 . The module case for a secondary battery according to claim 1 , which is manufactured by a resin transfer molding (RTM) method, a heterogeneous injection molding method, a pressing method, or a drawing method.

15. The module case for a secondary battery according to claim 1, wherein Each of the plurality of first layers has a thickness of less than 2 mm.

16. A module case for a secondary battery, the module case for a secondary battery being used to accommodate a battery cell laminate including a plurality of battery cells laminated along a first direction, in, The module case for a secondary battery is formed of a plate based on a composite material including fiber-reinforced plastic, Wherein, the plate comprises: a third layer disposed at the center based on a cross section of the plate in a thickness direction; a plurality of first layers arranged on an outer surface based on a cross section of the plate in the thickness direction; and a plurality of second layers arranged on both sides with the third layer therebetween and interposed between the plurality of first layers, wherein the plurality of first layers are formed of a fiber-reinforced plastic material having electrical insulating properties, wherein the plurality of second layers have higher mechanical strength than the plurality of first layers, and Wherein, the third layer includes at least one of basalt fiber and metal sheet.

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