Module frame for secondary battery and secondary battery including same

Abstract

The present invention provides a module frame and a secondary battery including the same, which utilize a composite material including fiber reinforced plastic (FIP) material, metal sheet, etc., and is lighter than conventional modules while having optimized characteristics for secondary batteries. The module frame for a secondary battery according to various embodiments is configured to accommodate a battery cell stack made up of a plurality of battery cells stacked in one direction, and the module frame is formed of a plate based on a composite material including fiber reinforced plastic. The plate may include at least a plurality of layers including a first layer and a second layer, and may have a layered cross section that is symmetrical in the thickness direction of the plate. Other embodiments are also possible.

Description

[Technical Field]

[0001] The present invention relates to a module frame for a secondary battery and a secondary battery including the same. [Background technology]

[0002] In modern society, the use of a variety of portable devices such as mobile phones, laptops, and digital cameras has become commonplace, and as a result, the development of battery-related technologies, an essential component of various mobile devices, is progressing vigorously.In addition, electric vehicles, which use electricity as a power source, are becoming more popular as an alternative to internal combustion engine vehicles, which have recently caused various problems such as environmental pollution.In line with this trend, there is an increasing need for the development of secondary batteries to be installed in electric vehicles.

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among these, lithium secondary batteries are attracting attention due to their advantages of free discharge, extremely low self-discharge rate, and high energy density, as they have almost no memory effect compared to other nickel-based secondary batteries.

[0004] In such lithium secondary batteries, lithium-based oxides and carbon materials are mainly used as the positive and negative electrode active materials, respectively. The lithium secondary battery includes a positive electrode plate and a negative electrode plate coated with the positive and negative electrode active materials, an electrode assembly including a separator disposed between the positive and negative electrode plates, and a battery case that seals and houses the electrode assembly together with an electrolyte.

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

[0006] Meanwhile, while secondary batteries used in small devices may be sufficient with only two or three battery cells, secondary batteries used in medium- to large-sized devices such as automobiles may need to be implemented in the form of a battery module in which multiple battery cells are electrically connected to improve capacity and output. Such a battery module may be mounted inside a secondary battery module frame in the form of a battery cell stack in which multiple battery cells are connected to each other in series or parallel. In addition, one or more battery modules may be mounted 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 stack is mounted can provide mechanical support for the battery cells that lack mechanical rigidity and can act as a case that protects the battery cells from external impacts, etc.

[0008] The module frame of a secondary battery can be manufactured in various forms depending on the module shape and structure of the secondary battery. For example, it can be manufactured in a square tube shape called a monoframe (see FIGS. 1b and 1c) or a U-shaped frame (see FIG. 1d).

[0009] Meanwhile, secondary battery module frames have generally been made primarily from metal materials (e.g., aluminum alloys) to protect the battery cell stack from external impacts or to facilitate storage. Summary of the Invention [Problem to be solved by the invention]

[0010] However, when manufacturing a module frame for a secondary battery using a metal material, there are limitations to reducing the weight of the secondary battery due to the material's characteristics, and the manufacturing method of the module frame is also limited.In addition, the product development process is limited to the use of uniform materials, making it difficult to realize product differentiation and diversification.In addition, with the trend toward larger capacity secondary batteries, there is an increasing need for the development of module frames that have the stress support capacity to withstand swelling of battery cells.

[0011] Various embodiments of the present disclosure have been devised to solve at least some of the problems of the prior art, and provide a module frame and a secondary battery including the same that are lighter than conventional modules and have characteristics optimized for secondary batteries by utilizing composite materials including fiber reinforced plastic (FRP) materials, metal sheets, etc. [Means for solving the problem]

[0012] To achieve the above-mentioned objectives, according to various embodiments of the present disclosure, a secondary battery module housing for accommodating a battery cell stack including a plurality of battery cells stacked along a first direction is formed by a plate based on a composite material including fiber-reinforced plastic, and the plate may include 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 the plurality of first layers and interposed between the plurality of first layers, and may have a layered cross-sectional structure that is symmetrical in the thickness direction of the plate.

[0013] For example, the second layer may be provided in a plurality of pieces, and the plate may include a third layer formed of a material different from each of the plurality of first layers and the plurality of second layers and interposed between the second layers.

[0014] For example, each of the plurality of first layers, each of the plurality of second layers, and the third layer may be composed of the same number of detailed layers as each other.

[0015] For example, each of the plurality of first layers, each of the plurality of second layers, and the third layer may have a layered cross-sectional structure that is symmetrical in the thickness direction.

[0016] For example, the at least one second layer may include at least one first fine fiber layer made of yarns arranged so that the direction corresponding to the principal stress direction of the plate is the length direction of the yarns; and at least one second fine fiber layer made of yarns arranged so that the direction corresponding to a direction other than the principal stress direction is the length direction of the yarns, and the number of the at least one first fine fiber layer may be greater than the number of the at least one second fine fiber layer.

[0017] For example, the at least one second fine fiber layer may include a fine fiber layer made of yarns arranged such that the direction corresponding to the secondary stress direction of the plate is the length direction of the yarns.

[0018] For example, the principal stress direction and the secondary stress direction may be perpendicular to each other.

[0019] For example, the at least one first fine fiber layer may include carbon fibers or glass fibers arranged at a higher density than the yarns making up the at least one second fine fiber layer.

[0020] For example, the third layer may include at least one of a detail layer comprised of basalt fiber or a detail layer comprised of a metal sheet of stainless steel material.

[0021] For example, each of the plurality of second layers and the third layer may have substantially the same thickness as each other.

[0022] For example, the third layer may include at least one first fine fiber layer composed of yarns arranged so that the direction corresponding to the principal stress direction of the plate is the length direction of the yarns; and at least one second fine fiber layer composed of yarns arranged so that the direction corresponding to the secondary stress direction of the plate is the length direction of the yarns, and the number of the at least one first fine fiber layer may be less than the number of the at least one second fine fiber layer.

[0023] For example, the module housing may further include a mounting flange located at the closed end of a side surface, and the mounting flange may be formed from the same material as the plate.

[0024] For example, the module housing can be manufactured by RTM, heterogeneous injection molding, pressing, or pultrusion.

[0025] For example, each of the first layers may have a thickness of less than 2 mm, or may have a thickness that is approximately half the thickness of the third layer.

[0026] According to various embodiments, a secondary battery module housing for accommodating a battery cell stack including a plurality of battery cells stacked along a first direction is formed of a plate based on a composite material including fiber-reinforced plastic, and the plate includes: a third layer disposed in the center based on a cross section in the thickness direction of the plate; a plurality of first layers disposed in the outer portion based on the cross section in the thickness direction of the plate; and a plurality of second layers disposed on both sides of the third layer and interposed between the plurality of first layers, the plurality of first layers being formed of a fiber-reinforced plastic material having electrical insulating properties, the plurality of second layers having greater mechanical strength than the plurality of first layers, and the third layer including at least one of basalt fiber or a metal sheet. [Effects of the Invention]

[0027] The secondary battery module frame and the secondary battery including the same according to various embodiments of the present disclosure may be configured to utilize a fiber reinforced plastic (FRP) material to have weight characteristics, mechanical strength (e.g., tensile strength) characteristics, rigidity characteristics, insulation characteristics, fire resistance characteristics, and / or manufacturing cost characteristics optimized for various types of secondary batteries.

[0028] Furthermore, by making the plate based on a composite material including a fiber-reinforced plastic material used to form the module frame have a layered cross-sectional structure that is symmetrical in the thickness direction, unnecessary manufacturing processes can be omitted and the problem of reduced durability at certain points of the module frame can be prevented.

[0029] In addition, even if a thermal event occurs in the secondary battery, the module frame with improved fire resistance can prevent the structural collapse of the secondary battery module itself or can help prevent thermal diffusion by blocking the inflow of oxygen.

[0030] In addition, a secondary battery with maximized structural stability can be provided by designing the module frame in consideration of the main stress direction that the secondary battery module must withstand, such as the swelling problem of the battery cells, and a module frame that can withstand greater internal pressure than conventional module frames can be provided.

[0031] On the other hand, the effects of the present invention are not suggested by the above-mentioned effects, and it is natural that the effects not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention pertains from this specification and drawings. [Brief explanation of the drawings]

[0032] [Figure 1a] 1 is a schematic exploded perspective view of a secondary battery module according to an embodiment of the present disclosure; [Figure 1b] 1 is a perspective view of a module frame for a secondary battery according to various embodiments of the present disclosure; [Figure 1c] 1 is a perspective view of a module frame for a secondary battery according to various embodiments of the present disclosure; [Figure 1d] 1 is a perspective view of a module frame for a secondary battery according to various embodiments of the present disclosure; [Figure 2] 1A-1C are cross-sectional views schematically illustrating the layered cross-sectional structure of plates that make up a module frame according to various embodiments of the present disclosure. [Figure 3] 1 is a schematic perspective view illustrating a principal stress direction and a secondary stress direction of a secondary battery module in a module frame according to various embodiments of the present disclosure; [Figure 4a] 1 is a diagram illustrating an example of the arrangement direction of radial yarns in each of a plurality of fiber layers constituting a first layer. [Figure 4b] 10 is a diagram illustrating an example of the arrangement direction of the yarns in each of a plurality of fiber layers constituting a second layer. [Figure 5a] 5A and 5B are schematic cross-sectional views of a module frame illustrating a principal stress direction and a secondary stress direction of the module frame due to a swelling phenomenon of a battery cell in various embodiments of the present disclosure. [Figure 5b] 1 is a schematic perspective view of a module frame illustrating a principal stress direction and a secondary stress direction of the module frame due to a swelling phenomenon of a battery cell in various embodiments of the present disclosure. FIG. [Figure 6a] 5A and 5B are schematic cross-sectional views of a module frame illustrating a principal stress direction and a secondary stress direction of the module frame due to an increase in internal pressure of a secondary battery module in various embodiments of the present disclosure. [Figure 6b] 1 is a schematic perspective view of a module frame illustrating a principal stress direction and a secondary stress direction of the module frame due to an increase in internal pressure of a secondary battery module in various embodiments of the present disclosure; DETAILED DESCRIPTION OF THE INVENTION

[0033] Prior to a detailed description of the present invention, the 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 as meanings and concepts consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that various equivalents and modified forms may exist as of the time of filing this application.

[0034] The same reference numbers or symbols in the drawings attached to this specification indicate parts or components that perform substantially the same functions. For ease of explanation and understanding, the same reference numbers or symbols may be used to describe different embodiments. In other words, even if components having the same reference numbers are shown in multiple drawings, this does not mean that all of the multiple drawings represent a single embodiment.

[0035] In the following description, the singular includes the plural unless the context clearly indicates otherwise. Terms such as "comprise" or "comprise" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the possibility of the presence or addition of one or more different features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] In addition, in the following description, expressions such as upper, top, lower, bottom, side, front, and rear are expressed based on the direction shown in the drawings, and it should be made clear in advance that they may be expressed differently if the direction of the corresponding object is changed.

[0037] Furthermore, in this specification and claims, terms including ordinal numbers such as "first," "second," etc. may be used to distinguish between elements. Such ordinal numbers are used to distinguish between identical or similar elements, and the meaning of the terms should not be limited by the use of such ordinal numbers. For example, the order of use or arrangement of elements combined with such ordinal numbers should not be limited by the numbers. If necessary, each ordinal number may be used interchangeably.

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the concept of the present invention is not limited to the illustrated embodiments. For example, a person skilled in the art who understands the concept of the present invention may propose other embodiments that fall within the scope of the concept of the present invention by adding, modifying, or deleting components, and these would also fall within the scope of the concept. In the drawings, the shapes and sizes of elements may be exaggerated for clarity.

[0039] Fig. 1a is a schematic exploded perspective view of a secondary battery module 100 according to an embodiment of the present disclosure. Figs. 1b to 1d are perspective views of a module frame 130 for a secondary battery according to various embodiments of the present disclosure.

[0040] 1a to 1d, a secondary battery module 100 according to various embodiments may include a battery cell stack including a plurality of battery cells 110 and a housing assembly that houses the battery cell stack. The housing assembly is for physically protecting the battery cell stack and may be configured to have predetermined mechanical strength and rigidity characteristics.

[0041] The housing assembly may include a module frame 130 (see FIGS. 1b-d) and cover assemblies 121,122.

[0042] For example, the housing assembly may include a module frame 130, a first cover assembly 121 covering a first side of an open end of the module frame 130 (e.g., the front, the end facing the +y direction), and a second cover assembly 122 covering a second side of the other open end of the module frame (e.g., the rear, the end facing the -y direction).

[0043] The module frame 130 may have a mono-frame structure as shown in Figures 1b and 1c, or a U-shaped structure as shown in Figure 1d. On the other hand, when the module frame 130 has a structure including a U-shaped frame as shown in Figure 1d, a third cover assembly (not shown) that covers a third side (e.g., a rear side, an end facing the +z direction), which is yet another open end of the U-shaped frame, may be further included as a housing assembly.

[0044] At least a portion of such a housing assembly may be formed from substantially the same material as module frame 130 (eg, fiber reinforced plastic) or may be formed from a simple metallic material (eg, aluminum alloy).

[0045] Illustratively, the battery cells 110 may include pouch-type battery cells.

[0046] A pouch-type battery cell may be formed by housing an electrode case in a pouch case made of a laminate sheet including a resin layer and a metal layer, and then heat-sealing the pouch case. In this case, the battery cell 110 may have a substantially rectangular sheet structure. However, the battery cell 110 included in a secondary battery module is not limited to a pouch-type battery cell. For example, the battery cell 110 may be a prismatic battery cell in which an electrode assembly is housed inside a prismatic case having a predetermined rigidity, or a cylindrical battery cell in which an electrode assembly is housed inside a cylindrical case.

[0047] A plurality of battery cells 110 can be provided to form a battery cell stack.

[0048] For example, the battery cells 110 constituting the battery cell stack may be electrically interconnected and stacked in a substantially parallel arrangement along one direction (e.g., the +x direction), which may be perpendicular to the direction in which gravity acts.

[0049] The module frame 130 in various embodiments may include a flange 131 on at least one side (e.g., on the closed side of both sides), as shown in FIG. 1b, or may not include a flange 131, as shown in FIG. 1c.

[0050] On the other hand, in one embodiment, when the module frame 130 includes a flange 131, such flange 131 may be formed based on substantially the same material (e.g., a composite material including at least one of fiber-reinforced plastic and a metal sheet) as the plate 200 that constitutes each surface (e.g., the upper surface, the lower surface, and the closing surfaces on both sides) of the module frame 130.

[0051] According to various embodiments of the present disclosure, the module frame 130 may be formed from a plate 200 based on a composite material, including fiber reinforced plastic, metal sheet, and the like.

[0052] Fiber-reinforced plastics can include a reinforcement that determines rigidity through a fiber material, etc., and a matrix resin that transmits the stress of the reinforcement and maintains the shape of the reinforcement or composite material. The matrix resin can be viscous and can permeate into at least one fiber layer that constitutes the reinforcement or between fiber layers, and then harden to form at least one fiber layer.

[0053] For example, the fiber material may include at least one of glass fiber, carbon fiber, basalt fiber, polymer fiber (e.g., Kevlar, nylon, polyester, aramid), ceramic fiber, or boron fiber.

[0054] The matrix resin may include at least one thermosetting resin material such as urethane or epoxy.

[0055] Meanwhile, in one embodiment, the composite material may further include at least one sheet material (e.g., polyethylene terephthalate (PET) sheet, polyurethane (PU) sheet, or metal (e.g., stainless steel) sheet) interposed between the fiber materials.

[0056] FIG. 2 is a cross-sectional view that schematically illustrates the layered cross-sectional structure of plates that make up each side of a module frame 130 according to various embodiments of the present disclosure.

[0057] Referring to FIG. 2 , the plate 200 forming the module frame 130 may include multiple layers (e.g., first layer 220, second layer 240, and third layer 260) having different properties. In particular, the plate 200 according to various embodiments of the present disclosure may have a layered structure that is symmetrical in the thickness direction. That is, the single-layer structure of the plate 200 from the inside to the outside of a module (e.g., the secondary battery module 100 of FIG. 1 a) and from the outside to the inside of the module may be identical in at least one aspect of material, thickness, or yarn arrangement. A plate 200 with a symmetrical layered cross-sectional structure may thus be advantageous in manufacturing because it does not require division of both sides. Furthermore, such a plate 200 may solve the problem of localized variations in stiffness across the surfaces of a manufactured module.

[0058] Specifically, the first layer 220 corresponding to the outermost layer of the plate 200 (eg, the layer disposed on the outermost side and the layer disposed on the innermost side of the secondary battery module) may be configured to have electrical insulating properties.

[0059] For example, the first layer 220 may include a fiber reinforced plastic having non-conductive properties (insulating properties), such as glass fiber, basalt fiber, aramid fiber, or the like.

[0060] In particular, in one embodiment, the first layer 220 may include a plurality of fine fiber layers, which may be arranged such that the orientation directions of the yarns constituting each fine fiber layer are interlaced with each other to form an overall radial structure.

[0061] Since the first layer 220 is disposed on the outer side of the plate 200, it may be most in need of protection from external physical forces. Furthermore, it may also be necessary to withstand not only the external physical forces but also the internal pressure generated within the frame of the secondary battery module. Therefore, if each of the first layers 220 (e.g., the 1-1 layer 220a and the 1-2 layer 220b) is configured with fine fiber layers that have an overall radial structure, the possibility of damage to the plate 200 can be minimized in each direction, regardless of the direction of the external force acting on the plate 200.

[0062] On the other hand, as an example, the main stress direction of the secondary battery module (e.g., the secondary battery module 100 in FIG. 1a) (i.e., the first direction corresponding to the direction of the highest specific gravity of the stress acting on the module frame 130 under the normal use environment of the secondary battery module) (e.g., the direction shown by the arrow “1” in FIGS. 3 and 4a) and the secondary stress direction of the secondary battery module (i.e., the second direction corresponding to the direction of the highest specific gravity of the stress acting on the module frame 130 under the normal use environment of the secondary battery module) (e.g., in a plane parallel to each plate 200 of the module frame 130, When a direction perpendicular to the first direction (e.g., the direction of arrow “2” in FIGS. 3 and 4a) is defined as two axes of 0 degree and 90 degree, respectively, the first layer 220 may be configured such that any one of “0 degree” (−180 degrees) (i.e., the main stress direction of the module), “90 degree” (−90 degrees) (i.e., the secondary stress direction of the module), “45 degree” (−135 degrees), or “135 degree” (−45 degrees) is aligned to the length direction of the yarns of each fine fiber layer, and such fine fiber layers are stacked to form a single fiber layer (e.g., 1-1 layer 220a or 1-2 layer 220b) having a radial structure. Meanwhile, it should be understood that the main stress direction of the secondary battery module may be a direction other than the direction of arrow “1” in FIGS. 3 and 4a (e.g., the direction of arrow “2” in FIGS. 3 and 4a) depending on the direction in which the battery cells 110 are arranged inside the module frame 130.

[0063] Meanwhile, according to various embodiments of the present disclosure, the module frame 130 may be configured to have the same symmetrical structure when viewed from either the inside or outside of the secondary battery module based on the layered cross section of the plate 200 .

[0064] For example, if the outermost layer 1-1 layer 220a of the plate 200 is formed by sequentially stacking a first fine 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 raw yarn, a second fine fiber layer arranged so that the "45 degree" (-135 degree) direction is the length direction of the raw yarn, and a third fine fiber layer arranged so that the "135 degree" (-45 degree) direction is the length direction of the raw yarn, based on either the inside to the outside or the outside to the inside of the specific plate 200, the corresponding innermost layer 1-2 layer 220b of the plate 200 is formed by sequentially stacking the third fine fiber layer, the second fine fiber layer, and the first fine fiber layer, thereby realizing a symmetrical structure of the plate 200.

[0065] Meanwhile, the first layer 220 may have a radial structure and may be configured to include fine fiber layers arranged to face at angles of 30 degrees (-150 degrees) or 60 degrees (-120 degrees) in addition to the aforementioned directions of 0 degrees, 90 degrees, 45 degrees, and 135 degrees, and various other radial structures not mentioned above may also be considered. In this way, in the module frame 130 according to various embodiments of the present disclosure, stress acting on the first layer 220 of each plate 200 can be dispersed in multiple directions to ensure structural stability.

[0066] Meanwhile, when manufacturing a module frame 130 using metal as in the past, an insulating coating had to be applied to at least a portion of the surface facing the cells 110 (or cell stack), or the insulating coating had to be applied directly to the outer surface of the cells 110 (or cell stack). However, in the module frame 130 according to various embodiments of the present disclosure, each outermost layer of the plate 200 can have insulating properties, so that the insulating coating process on the outer surface of the module frame 130 or the outer surface of the cells 110, which was previously performed, can be omitted.

[0067] Next, the second layer 240 is a layer interposed between the first layer 220, which corresponds to the outermost layer of the plate 200, and the third layer 260, which corresponds to the central layer of the plate 200, and may be a layer having superior mechanical strength properties (e.g., tensile strength) or rigidity properties than the other layers.

[0068] For example, the first layer 220 and the second layer 240 may differ in the number of fiber bundles that make up each layer. The first layer 220 and the second layer 240 may be classified based on whether they have targeted strength or stiffness characteristics. For example, the first layer 220 may have a stiffness that is less than or equal to that of an aluminum alloy, while the second layer 240 may have a stiffness that is greater than that of the aluminum alloy.

[0069] In an embodiment, the second layer 240 may be defined as a layer in which the number of yarns (or the number of fine fiber layers) arranged such that the length direction of the yarns is the first direction (the aforementioned 0-degree direction) (e.g., the direction shown by arrow "1" in FIG. 3 ) corresponding to the principal stress direction of the secondary battery module 100 is greater than the number of yarns (or the number of fine fiber layers) arranged in other directions. This ensures mechanical rigidity in the second layer 240 against the principal stress direction of the module. For example, the number of yarns (or the number of fine fiber layers) corresponding to the principal stress direction may be approximately 50% or more of the total number of yarns (or the total number of fine fiber layers) in the second layer 240.

[0070] For example, the second layer 240 may include at least one of glass fiber, carbon fiber, basalt fiber, and aramid fiber. For example, in one embodiment, the second layer 240 may include at least one fine fiber layer made of carbon fiber arranged such that the first direction (i.e., the principal stress direction of the module 100) is the length direction of the carbon fiber yarn.

[0071] However, the present invention is not limited to this embodiment. For example, in another embodiment, the second layer 240 may not include a fine fiber layer made of carbon fiber, but may instead have a fine fiber layer made of glass fiber oriented so that the first direction is the length direction of the fiber, the fine fiber layer having a higher yarn density than the fine fiber layer of another layer (e.g., the fine fiber layer made of glass fiber in the first layer 220). In this case, there may be an advantage that the second layer 240 can be formed while ensuring a certain level of rigidity without using expensive carbon fiber.

[0072] In embodiments, the second layer 240, like the first layer 220, can also include multiple fine fiber layers.

[0073] For example, the second layer 240 may include a fine fiber layer in which yarns are arranged to face a first direction (e.g., the direction of arrow "1" in FIGS. 3 and 4b), which is the principal stress direction of the module. The second layer 240 may also include a fine fiber layer in which yarns are arranged to face a secondary stress direction of the module (i.e., a second direction perpendicular to the first direction on the plane of the plate 200) (e.g., the direction of arrow "2" in FIGS. 3 and 4b). For example, when the second layer 240 includes a fine fiber layer in which yarns are arranged to face the secondary stress direction, the number of fine fiber layers corresponding to the secondary stress direction may be less than or equal to the number of fine fiber layers corresponding to the principal stress direction.

[0074] Meanwhile, in the case of the second layer 240, the second-1st layer 240a and the second-2nd layer 240b may be formed so that they are symmetrical to each other in terms of material, thickness, and / or yarn arrangement, based on the third layer 260, which is the central layer of the plate 200.

[0075] Next, the third layer 260 is a layer disposed at the center in the layered cross-sectional structure of the plate 200, and may correspond to a layer having stronger fire resistance than 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 with a high melting point and low thermal conductivity.

[0076] For example, the third layer 260 may be configured to include at least one of basalt fiber or a metal sheet of stainless steel material.

[0077] Generally, when a module frame 130 for a secondary battery is formed from a composite material including fiber-reinforced plastic, it may be more vulnerable to thermal runaway of the secondary battery than a conventional module frame 130 made only of metal material. However, in the case of the module frame 130 according to various embodiments of the present disclosure, a third layer 260 with enhanced fire resistance is provided in the center, thereby effectively preventing structural collapse of the module frame 130 in high temperature or high pressure environments.

[0078] Meanwhile, in one embodiment, the third layer 260 may be formed with a thickness greater than that of the first layer 220 (e.g., the first layer 220a or the first layer 220b) or the second layer 240 (e.g., the second layer 240a or the second layer 240b) (e.g., approximately twice the thickness of the first layer 220a, 220b, or the second layer 240a, 240b). Alternatively, in other embodiments, the layers (e.g., the first layer 220a, the second layer 240a, the third layer 260, the second layer 240b, and the first layer 220b) may be formed with substantially the same thickness or may be configured to include the same number of detail layers (fiber detail layers or metal sheet layers corresponding to fiber detail layers). For example, each layer may be configured to include four detail layers (or five detail layers). In yet another embodiment, only the second layer 240 (i.e., the 2-1 layer 240a and the 2-2 layer 240b) and the third layer 260 may be configured to have the same thickness or include the same number of sublayers, and the first layer 220 (i.e., the 1-1 layer 220a and the 1-2 layer 220b) with respect to electrical insulation properties may be configured to have a smaller thickness or include fewer sublayers than the second layer 240 or the third layer 260. For example, each of the first layers 220, 220a, and 220b may have a thickness of 2 mm or less, and the layers other than the first layer 220 may have a thickness of 2 mm or more.

[0079] In addition, in an embodiment, the arrangement direction of the yarns constituting the fine fiber layers included in the third layer 260 may correspond to the main stress direction (e.g., the first direction (direction indicated by arrow "1") in FIG. 3) or the sub-stress direction (e.g., the second direction (direction indicated by arrow "2") in FIG. 3) of the secondary battery module 100. For example, the number of fine fiber layers arranged to correspond to the main stress direction among the fine fiber layers included in the third layer 260 may be the same as or less than the number of fine fiber layers arranged to correspond to the sub-stress direction. Meanwhile, in another embodiment, the arrangement direction of the yarns constituting the fine fiber layers included in the third layer 260 may be a direction other than the main stress direction or the sub-stress direction of the secondary battery module 100. For example, the fine fiber layers included in the third layer 260 may have a radial yarn arrangement.

[0080] In various embodiments, the third layer 260 may be configured to include the aforementioned fiber material (basalt fiber) or metal sheet having excellent fire resistance. However, since the third layer 260 includes such a material having excellent fire resistance in a detail layer (a detail fiber layer or a metal sheet layer corresponding to the detail fiber layer), the third layer 260 may further include another detail fiber layer made of a material other than the aforementioned material (e.g., glass fiber, aramid fiber, carbon fiber, etc.). In this case, however, it may be less preferable for a detail layer made of a fiber material having excellent fire resistance to be disposed in the outermost layer of the third layer 260 (i.e., a detail layer adjacent to the second layer 240 (e.g., the 2-1 layer 240a and the 2-2 layer 240b)).

[0081] In various embodiments, plate 200 may have a layered cross-sectional structure that is generally symmetrical in the thickness direction. Furthermore, in one embodiment of the present disclosure, each layer constituting plate 200 (e.g., first layer 220 (i.e., 1-1 layer 220a and 1-2 layer 220b), second layer 240 (i.e., 2-1 layer 240a and 2-2 layer 240b), and third layer 260) may have a layered structure that is symmetrical in the thickness direction of plate 200. In this manner, when each layer (e.g., first layer 220, 220a, 220b, second layer 240, 240a, 240b, and third layer 260) has a symmetrical structure that does not have a specific direction in the thickness direction, even when each layer is manufactured in advance as a semi-finished product and then joined to manufacture plate 200, the vertical orientation of each layer does not need to be considered, which may simplify the manufacturing process. In addition, since the isotropic properties are ensured for each layer, the structural stability can be further improved, and there is an advantage that the structural stability can be maintained even when the drawing process or pressing process described below is applied to the plate 200.

[0082] Meanwhile, in another embodiment, plate 200 has a structure in which the yarns are arranged in a completely symmetrical direction without any particular directionality in the thickness direction, whereas each layer (e.g., first layer 220, 220a, 220b, second layer 240, 240a, 240b, third layer 260) constituting plate 200 has a completely symmetrical structure in the thickness direction in terms of material and thickness, but the yarns of two detailed layers may be arranged in line symmetry with respect to the principal stress direction. For example, if the yarns of the detailed layer arranged on the innermost side of one layer have an angle difference of A° with respect to the principal stress direction, the yarns of the detailed layer arranged on the outermost side may have an angle difference of 180-A° with respect to the principal stress direction.

[0083] Meanwhile, the module frame 130 according to various embodiments of the present disclosure may be manufactured using an RTM (resin transfer molding) method, or at least one of a heterogeneous injection method, a press method, and a drawing method.

[0084] For example, when the module frame 130 is manufactured using a drawing method, the module frame 130 can be manufactured by bending a single plate 200 based on a composite material including fiber-reinforced plastic according to various embodiments of the present disclosure into a C-shape (or U-shape) and then joining it with another plate.

[0085] In addition, in one example, when at least one flange 131 is included on a side of the module frame 130 (see FIG. 1b), if the module frame 130 is manufactured by the RTM method, the flange 131 may be formed integrally with the main body of the module frame 130. However, if the module frame 130 is manufactured by a pultrusion method or the like, the flange 131 may be formed by adhering a part of the flange 131 made of the material of the plate 200 of the module frame 130 to the side of the main body of the module frame 130 using an adhesive or the like. In this case, the flange 131 may have the same structure as the plate 200 on the upper or lower surface of the module frame 130 in terms of the material and arrangement direction of the yarn. Meanwhile, in one example, even if the module frame 130 is manufactured by the pultrusion method, the flange 131 and the main body of the module frame 130 may be formed integrally.

[0086] FIG. 3 is a schematic perspective view illustrating a principal stress direction and a secondary stress direction of the secondary battery module 100 in the module frame 130 according to various embodiments of the present disclosure.

[0087] As mentioned above, in FIG. 3, the first direction (the direction shown by the arrow "1") may be the main stress direction of the secondary battery module 100, the second direction (the direction shown by the arrow "2") may be the secondary stress direction of the secondary battery module 100, and the third direction (the direction shown by the arrow "3") may be a direction perpendicular to each of the first and second directions (for example, the thickness direction of each plate 200 constituting the module frame 130).

[0088] For example, the first direction may correspond to a direction parallel to the circumferential direction of the rectangular tube-shaped or U-shaped body of the module frame 130, and the second direction may correspond to a direction from the first open end (e.g., the front face) to the second open end (e.g., the rear face) of the module frame 130 (e.g., a direction parallel to the direction in which the electrode tabs of the cells 110 face).

[0089] However, such direction setting may be applied differently in consideration of the direction in which the battery cells 110 are arranged in the module frame 130 in the secondary battery module 100. As a result, in another embodiment, the second direction (the direction shown by the arrow "2") in FIG. 3 may be the principal stress direction of the secondary battery module 100.

[0090] FIG. 4a is a diagram illustrating an example of the arrangement direction of radial yarns in each fine fiber layer constituting the first layer 220, and FIG. 4b is a diagram illustrating an example of the arrangement direction (e.g., the main stress direction (first direction) or the secondary stress direction (second direction)) of yarns in each fine fiber layer constituting the second layer 240 (or the third layer 260).

[0091] For ease of explanation, in Figures 4a and 4b, the axis corresponding to "0 degrees" is set to the first direction, which is the main stress direction of the secondary battery module 100, and the axis corresponding to "90 degrees" is set to the second direction, which is the secondary stress direction of the secondary battery module 100, as described above with reference to Figure 2.

[0092] 5a and 5b are schematic cross-sectional and perspective views of a module frame 130 for explaining the principal and secondary stress directions of the module frame 130 due to the swelling phenomenon of the battery cell 110 in various embodiments of the present disclosure.

[0093] 6a and 6b are schematic cross-sectional and perspective views of the module frame 130 to explain the main stress direction and secondary stress direction of the module frame 130 due to an increase in internal pressure of the secondary battery module 100 in various embodiments of the present disclosure.

[0094] 5a and 5b, in a secondary battery module 100, the battery cells 110 (or battery cell stack) housed inside the module frame 130 may be arranged in a row along one direction (e.g., the x-axis direction, see FIG. 1a, etc.). Meanwhile, if swelling occurs in such battery cells 110 (or battery cell stack), the volume of the cells increases in the stacking direction of the battery cells 110, which may pressurize both sides of the module frame 130 (e.g., the closed surfaces on both sides of the module frame 130). Therefore, the module frame 130 may need to absorb and support the associated pressure.

[0095] For example, when swelling occurs in the battery cell 110 (or the battery cell stack), expansion pressure occurs in a direction perpendicular to the main body (the portion housing the electrode assembly) of the battery cell 110 (e.g., the x-axis direction in FIG. 5a), and as a result, stress may occur on the side of the module frame 130 in a direction that resists this expansion pressure.

[0096] 5a, the expansion pressure of the battery cells 110 (or the battery cell stack) may act most strongly in each central region in the height direction (e.g., z-axis direction) of the side of the module frame 130, and as a result, relatively large tensile forces may be generated in the side of the module frame 130 in directions 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, as shown in Figures 5a and 5b. In other words, due to the swelling phenomenon of the battery cells 110 (or the battery cell stack), among stresses in multiple directions, relatively large stress may be generated in the z-axis direction in the side of the module frame 130 (closed end of the side of the module frame 130).

[0097] Therefore, in the module frame 130 according to various embodiments of the present disclosure, the swelling phenomenon can be effectively compensated for by setting the z-axis direction (first direction) perpendicular to the y-axis as the principal stress direction when the side plane of the module frame 130 is used as a reference.

[0098] Furthermore, when pouch-type battery cells 110 are stacked in the x-axis direction, each battery cell 110 has a long shape in the y-axis direction, and therefore the module frame 130 can also receive a large force in a direction parallel to the y-axis at its side (e.g., end parallel to the yz plane).

[0099] In particular, in the case of a pouch cell with a large aspect ratio, the change in cell volume due to swelling can be large at the center of the battery cell 110 based on the y-axis. Therefore, in the module frame 130 according to various embodiments of the present disclosure, the y-axis direction (second direction) perpendicular to the principal stress direction is set as the secondary stress direction, and the module frame 130 uses a composite material including fiber-reinforced plastic with a radial or other type of yarn arrangement structure, thereby minimizing structural deformation due to the swelling phenomenon.

[0100] Meanwhile, referring to Figures 6a and 6b, an increase in the internal pressure of the secondary battery module 100 may cause a bulging phenomenon in the module frame 130, and as a result, internal pressure may act on the surface of each plate 200 of the module frame 130 in a direction from the inside to the outside of the module 100 (in the direction of the solid arrow in Figure 6a).

[0101] According to various embodiments of the present disclosure, the principal stress direction and secondary stress direction can be determined by comprehensively considering the acting direction of the internal pressure of the secondary battery module 100, the acting direction of the swelling described with reference to Figures 5a and 5b, and the manufacturing method of the module frame 130, including the drawing method, and the yarn arrangement direction can be determined.

[0102] For example, in one embodiment of the present disclosure, a first direction parallel to the circumferential direction of the rectangular tubular or U-shaped body of the module frame 130 (e.g., the direction indicated by arrow "1" in FIG. 3 ) is set as the principal stress direction, and a longitudinal direction of the body from the first open end to the second open end of the module frame 130 (e.g., the direction indicated by arrow "2" in FIG. 3 ) is set as the secondary stress direction. The yarn arrangement direction of each fiber layer constituting the plate 200 is determined accordingly, thereby providing a module frame 130 with maximized rigidity in consideration of the application and manufacturing method of the secondary battery module frame 130. Alternatively, in another embodiment, another specific direction (e.g., the longitudinal direction of the body) may be set as the principal stress direction based on the arrangement direction of the battery cells 110, and another specific direction (e.g., a first direction parallel to the circumferential direction of the body of the module frame 130) may be set as the secondary stress direction in consideration of the principal stress direction, thereby determining the yarn arrangement direction of each fiber layer.

[0103] Furthermore, when the module frame 130 is formed from a composite material including fiber-reinforced plastic, as in various embodiments of the present disclosure, the module frame 130 has the same or higher tensile strength as when the module frame 130 is formed from a general metal material, but the composite material may have a lower Young's modulus than metal. This allows the module frame 130 to have high rigidity capable of responding to swelling of the battery cells 110 while also having elastic properties that can effectively absorb swelling. In addition, since the composite material is lighter than metal, it can have the effect of reducing the weight of the secondary battery and increasing the energy density.

[0104] In addition, the strength, elastic modulus, fire resistance, etc. of each material can be adjusted to meet the requirements of various types of secondary batteries, which has the advantage of providing greater design freedom compared to conventional module frames 130 made of metal materials.

[0105] Although various embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical idea of ​​the present invention as set forth in the claims. In addition, some components of the above-described embodiments may be omitted, and the embodiments may be combined with each other. [Explanation of symbols]

[0106] 100 secondary battery module 110 battery cells 121 First cover assembly 122 Second cover assembly 130 Module Frame 131 flange 200 plates 220, 220a, 220b 1st layer 240, 240a, 240b 2nd layer 260 3rd layer

Claims

1. A secondary battery module housing for accommodating a battery cell stack including a plurality of battery cells stacked along a first direction, the secondary battery module housing is formed by a plate based on a composite material including fiber-reinforced plastic; The plate is a plurality of first layers formed of a fiber-reinforced plastic material having electrical insulating properties; 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; A secondary battery module housing having a layered cross-sectional structure symmetrical in the thickness direction of the plate.

2. The second layer is provided in a plurality of pieces, The plate is The secondary battery module housing according to claim 1 , further comprising a third layer formed of a material different from each of the plurality of first layers and the plurality of second layers and interposed between the second layers.

3. Each of the plurality of first layers, each of the plurality of second layers, and the third layer are 3. The secondary battery module housing according to claim 2, wherein each of the plurality of detail layers is the same in number as each other.

4. Each of the plurality of first layers, each of the plurality of second layers, and the third layer are 3. The secondary battery module housing according to claim 2, which is composed of a plurality of small layers each having a layered cross-sectional structure symmetrical in the thickness direction.

5. each of the plurality of first layers includes a plurality of fine fiber layers; 2. The module housing for a secondary battery according to claim 1, wherein the arrangement direction of the yarns constituting any one of the plurality of fine fiber layers corresponds to the arrangement direction of the yarns constituting the remaining fine fiber layers, forming a radial structure.

6. The at least one second layer comprises: at least one first fine fiber layer made of yarns arranged such that a direction corresponding to a principal stress direction of the plate is a length direction of the yarns; at least one second fine fiber layer formed of yarns arranged such that a direction corresponding to a direction other than the principal stress direction is the length direction of the yarns, The secondary battery module housing according to claim 1 , wherein the number of the at least one first fine fiber layer of the at least one second layer is greater than the number of the at least one second fine fiber layer.

7. The at least one second fine fiber layer of the at least one second layer comprises:

7. The secondary battery module housing according to claim 6, wherein the housing is made of yarns arranged so that the direction corresponding to the secondary stress direction of the plate is the length direction of the yarns.

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

9. The at least one first fine fiber layer of the at least one second layer comprises: Contains carbon fiber or 7. The secondary battery module housing according to claim 6, wherein the at least one second layer includes glass fibers having a density greater than that of the original yarns constituting the at least one second fine fiber layer.

10. The third layer is 3. The secondary battery module housing according to claim 2, comprising at least one of a detail layer made of basalt fiber or a detail layer made of a metal sheet of stainless steel material.

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

12. The third layer is At least one first fine layer made of yarns arranged so that the direction corresponding to the principal stress direction of the plate is the length direction of the yarns; At least one second detailed layer is formed by yarns arranged such that a direction corresponding to a secondary stress direction of the plate is a length direction of the yarns, The secondary battery module housing according to claim 2 , wherein the number of the at least one first sub-layer of the third layer is less than the number of the at least one second sub-layer of the third layer.

13. the secondary battery module housing further includes a mounting flange located at a closed end of a side surface, The secondary battery module housing according to claim 1 , wherein the mounting flange is made of the same material as the plate.

14. The secondary battery module housing according to claim 1 , wherein the secondary battery module housing is manufactured by an RTM method, a heterogeneous injection method, a press method, or a drawing method.

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

16. A secondary battery module housing for accommodating a battery cell stack including a plurality of battery cells stacked along a first direction, the secondary battery module housing is formed by a plate based on a composite material including fiber-reinforced plastic; The plate is a third layer disposed at a center portion of the plate with respect to a cross section in a thickness direction of the plate; A plurality of first layers are arranged in an outer shell portion based on a cross section in a thickness direction of the plate; a plurality of second layers disposed on both sides of the third layer and interposed between the plurality of first layers; the plurality of first layers are formed of a fiber-reinforced plastic material having electrical insulating properties; the plurality of second layers have a greater mechanical strength than the plurality of first layers; The module housing for a secondary battery, wherein the third layer includes at least one of a basalt fiber or a metal sheet.

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