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 multiple battery cells stacked along one direction, wherein the module frame is formed by a composite material-based plate including fiber reinforced plastic; and the plate includes at least multiple layers including a first layer and a second layer and has a layered cross-section symmetrical in the thickness direction of the plate. In addition, other embodiments are possible.

Description

Module frame for secondary battery and secondary battery including same

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

[0002] In modern society, the use of various portable devices, such as cell phones, laptops, and digital cameras, has become commonplace. Consequently, the development of battery technology, an essential component of these devices, is actively underway. Furthermore, electric vehicles, powered by electricity, are emerging as a viable alternative to internal combustion engine vehicles, which have been associated with various environmental problems, including pollution. In response to this trend, the need for the development of secondary batteries for electric vehicles is increasing.

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are attracting attention for their advantages, including virtually no memory effect compared to other nickel-based secondary batteries, free charging and discharging, a very low self-discharge rate, and high energy density.

[0004] In these lithium secondary batteries, lithium oxides and carbon materials can be mainly used as the positive electrode active material and the negative electrode active material, respectively. The lithium secondary battery can include an electrode assembly comprising a positive electrode plate and a negative electrode plate on which the positive electrode active material and the negative electrode active material are respectively coated, and a separator disposed between the positive electrode plate and the negative electrode plate, and a battery case that seals and houses the electrode assembly together with an electrolyte.

[0005] In general, lithium secondary batteries can be classified into can-type secondary batteries in which the electrode assembly is built into a metal can, and pouch-type secondary batteries in which the electrode assembly is built into a pouch of an aluminum laminate sheet, depending on the shape of the outer packaging material.

[0006] Meanwhile, while secondary batteries used in small devices may be sufficiently configured with only 2-3 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 a plurality of 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 a plurality of 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 BMS (Battery Management System) and a cooling system to form a battery pack.

[0007] In this way, the module frame of the secondary battery in which the battery cell stack is mounted can provide mechanical support for the battery cells that lack mechanical rigidity and serve as a case to protect the battery cells from external impacts, etc.

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

[0009] Meanwhile, the module frame of a secondary battery is usually made of metal material (e.g., aluminum alloy) to protect the battery cell stack from external impact or to facilitate storage.

[0010] However, manufacturing secondary battery module frames using metal materials has limited the ability to reduce the weight of secondary batteries due to their material properties. Manufacturing methods for module frames have also been limited, and the product development process has been limited to using uniform materials, making it difficult to differentiate and diversify products. Furthermore, with the trend toward larger secondary battery capacities, the need for module frames capable of withstanding cell swelling is growing.

[0011] Various embodiments of the present disclosure have been devised to solve at least some of the problems of the prior art as described above, and provide a module frame that is lighter than the prior art and has characteristics optimized for a secondary battery by utilizing a composite material including a fiber reinforced plastic (FRP) material, a metal sheet, etc., and a secondary battery including the same.

[0012] According to various embodiments of the present disclosure for achieving the above object, 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 a fiber-reinforced plastic, wherein the plate includes 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 symmetrical in the thickness direction of the plate.

[0013] For example, the second layer may be provided in multiple numbers, and the plate may include a third layer formed of a different material from 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 each of the third layer may each be composed of a plurality of sublayers having the same number of sublayers.

[0015] For example, each of the plurality of first layers, each of the plurality of second layers, and each of 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 includes at least one first detailed fiber layer composed of yarns arranged such that a direction corresponding to the principal stress direction of the plate is the longitudinal direction of the yarns; and at least one second detailed fiber layer composed of yarns arranged such that a direction corresponding to a direction other than the principal stress direction is the longitudinal direction of the yarns, and the number of the at least one first detailed fiber layer may be greater than the number of the at least one second detailed fiber layer.

[0017] For example, the at least one second detailed fiber layer may comprise a detailed fiber layer composed of yarns arranged such that the direction corresponding to the stress direction of the plate is the longitudinal 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 detailed fiber layer may comprise carbon fibers or may comprise glass fibers having a greater density than the yarns making up the at least one second detailed fiber layer.

[0020] For example, the third layer may include at least one of a sublayer composed of basalt fibers or a sublayer composed of a metal sheet made of stainless steel.

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

[0022] For example, the third layer includes at least one first detailed layer composed of yarns arranged such that the direction corresponding to the principal stress direction of the plate is the longitudinal direction of the yarns; and at least one second detailed layer composed of yarns arranged such that the direction corresponding to the non-stress direction of the plate is the longitudinal direction of the yarns, and the number of the at least one first detailed fiber layer may be less than the number of the at least one second detailed fiber layer.

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

[0024] For example, the module housing can be manufactured by RTM method, heterogeneous injection molding method, press method, or drawing method.

[0025] For example, 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 that is about 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 by a plate based on a composite material including fiber-reinforced plastic, wherein the plate includes: a third layer disposed at a center portion based on a thickness-wise cross-section of the plate; a plurality of first layers disposed at an outer portion based on a thickness-wise cross-section 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, wherein the plurality of first layers are formed of a fiber-reinforced plastic material having electrical insulating properties, the plurality of second layers have a mechanical strength greater than that of the plurality of first layers, and the third layer may include at least one of basalt fibers or a metal sheet.

[0027] A secondary battery module frame and a secondary battery including the same according to various embodiments of the present disclosure can be configured 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 by utilizing fiber reinforced plastic (FRP) materials.

[0028] In addition, by making the composite material-based plate including the fiber-reinforced plastic material used to form the module frame have a layered cross-sectional structure symmetrical in the thickness direction, unnecessary manufacturing processes can be omitted and the problem of durability deterioration at a specific point of the module frame can be prevented.

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

[0030] Furthermore, by designing the module frame to address key stress directions that secondary battery modules must withstand, such as battery cell swelling, it is possible to provide a secondary battery with maximized structural stability. Furthermore, it is possible to provide a module frame capable of withstanding greater internal pressure than conventional module frames.

[0031] Meanwhile, the effects of the present invention are not suggested by the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from the present specification and drawings.

[0032] FIG. 1A is a schematic exploded perspective view of a secondary battery module according to one embodiment of the present disclosure.

[0033] FIGS. 1b to 1d are perspective views of a module frame for a secondary battery according to various embodiments of the present disclosure.

[0034] FIG. 2 is a cross-sectional view schematically illustrating a layered cross-sectional structure of plates constituting a module frame according to various embodiments of the present disclosure.

[0035] FIG. 3 is a schematic perspective view for explaining the primary stress direction and secondary stress direction of a secondary battery module in a module frame according to various embodiments of the present disclosure.

[0036] FIG. 4a is a drawing exemplarily showing the radial yarn arrangement direction of each of the plurality of fiber layers constituting the first layer.

[0037] Figure 4b is a drawing exemplarily showing the arrangement direction of yarns in each of the plurality of fiber layers constituting the second layer.

[0038] FIGS. 5A and 5B are schematic cross-sectional views and perspective views of a module frame for explaining the principal stress direction and the secondary stress direction of the module frame according to the battery cell swelling phenomenon in various embodiments of the present disclosure.

[0039] FIGS. 6A and 6B are schematic cross-sectional views and perspective views of a module frame for explaining the direction of the main stress and the direction of the secondary stress of the module frame according to the increase in internal pressure of the secondary battery module in various embodiments of the present disclosure.

[0040] Before going into the detailed description of the present invention, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted with meanings and concepts that conform to 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 explain his own invention in the best way. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of ​​the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0041] The same reference numbers or symbols used in each drawing attached to this specification represent parts or components that perform substantially the same functions. For convenience of explanation and understanding, the same reference numbers or symbols may be used in different embodiments. In other words, even if components with the same reference numbers are depicted in multiple drawings, they do not necessarily represent a single embodiment.

[0042] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprises" or "comprises" should be understood to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0043] In addition, in the description below, expressions such as top, upper, lower, lower, side, front, and rear are expressed based on the direction shown in the drawing, and it is noted in advance that they may be expressed differently if the direction of the object in question changes.

[0044] Additionally, terms including ordinal numbers, such as "first," "second," etc., may be used in this specification and claims to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from each other, and the use of these ordinal numbers should not be interpreted in a limited manner. For example, components associated with these ordinals should not be interpreted in a restricted manner, such as in the order of use or arrangement, based on their numbers. If necessary, each ordinal number may be used interchangeably.

[0045] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments. For example, those skilled in the art who understand the spirit of the present invention may propose other embodiments within the spirit of the present invention by adding, modifying, or deleting components, etc., but these will also be considered to be within the spirit of the present invention. In the drawings, the shapes and sizes of elements may be exaggerated for clarity.

[0046] FIG. 1A is a schematic exploded perspective view of a secondary battery module (100) according to one 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.

[0047] Referring to FIGS. 1A to 1D , a secondary battery module (100) according to various embodiments may include a battery cell stack composed of a plurality of battery cells (110) and a housing assembly that accommodates the battery cell stack. The housing assembly is intended to physically protect the battery cell stack and may be configured to have predetermined mechanical strength and rigidity characteristics.

[0048] The housing assembly may include a module frame (130) (see FIGS. 1b to 1d) and a cover assembly (121, 122).

[0049] For example, the housing assembly may include a module frame (130), a first cover assembly (121) covering a first side (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 (e.g., a rear side, an end facing the -y direction) of the other open end of the module frame.

[0050] The module frame (130) may have a mono-frame structure as illustrated in FIGS. 1b and 1c, or a U-shaped structure as illustrated in FIG. 1d. Meanwhile, when the module frame (130) has a structure including a U-shaped frame as illustrated in FIG. 1d, a third cover assembly (not illustrated) covering another open end of the U-shaped frame, that is, a third side (e.g., an upper surface, an end facing the +z direction), may be further included as a housing assembly.

[0051] At least a portion of such a housing assembly may be formed of substantially the same material as the module frame (130), such as fiber-reinforced plastic, or may be formed of a simple metal material, such as an aluminum alloy.

[0052] For example, the battery cell (110) may include a pouch-type battery cell.

[0053] A pouch-type battery cell can be formed by housing an electrode case in a pouch case of a laminate sheet including a resin layer and a metal layer, and then heat-fusing the sealing portion of the pouch case. At this time, the battery cell (110) can have a substantially rectangular sheet-shaped 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 be a square battery cell in which an electrode assembly is housed inside a square case having a predetermined rigidity, or may be configured as a cylindrical battery cell in which an electrode assembly is housed inside a cylindrical case.

[0054] A plurality of battery cells (110) can be provided to form a battery cell stack.

[0055] For example, a plurality of battery cells (110) constituting a battery cell stack may be electrically interconnected and arranged in a substantially parallel stack along one direction (e.g., +x direction). For example, the one direction may be perpendicular to the direction in which gravity acts.

[0056] The module frame (130) according to various embodiments may include a flange (131) on at least one side (e.g., closed sides on both sides) as illustrated in FIG. 1b, and may not include a flange (131) as illustrated in FIG. 1c.

[0057] Meanwhile, in one embodiment, when the module frame (130) includes a flange (131), the flange (131) may be formed based on a material substantially the same as that of the plate (200) constituting each surface (e.g., the upper surface, the lower surface, and the closed surfaces of both sides) of the module frame (130) (e.g., a composite material including at least one of a fiber-reinforced plastic and a metal sheet).

[0058] According to various embodiments of the present disclosure, the module frame (130) may be formed of a plate (200) based on a composite material including fiber reinforced plastic, metal sheet, etc.

[0059] Fiber-reinforced plastics may include a reinforcement material that determines stiffness through fiber materials, and a matrix resin that transmits the stress of the reinforcement material and maintains the shape of the reinforcement material or composite material. The matrix resin may be viscous and may permeate within at least one fiber layer constituting the reinforcement material or between fiber layers, and may then harden to form at least one fiber layer.

[0060] 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.

[0061] The base material may include at least one thermosetting resin material such as urethane or epoxy.

[0062] Meanwhile, in one embodiment, the composite material may further include a sheet material (e.g., at least one of a polyethylene terephthalate (PET) sheet, a polyurethane (PU) sheet, or a metal (e.g., stainless steel) sheet) interposed between the fiber materials.

[0063] FIG. 2 is a cross-sectional view schematically illustrating a layered cross-sectional structure of plates constituting each side of a module frame (130) according to various embodiments of the present disclosure.

[0064] Referring to FIG. 2, the plate (200) forming the module frame (130) may include a plurality of layers (e.g., a first layer (220), a second layer (240), and a 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) when facing outward from the inside of the module (e.g., the secondary battery module (100) of FIG. 1) and when facing inward from the outside of the module may be identical in at least one aspect of the material, thickness, or arrangement of yarns. The plate (200) having such a symmetrical layered cross-sectional structure may have an advantage in the manufacturing process because there is no need to distinguish between the two sides. In addition, the problem of local differences in stiffness on each side of a module manufactured by such a plate (200) can be solved.

[0065] Specifically, the first layer (220) corresponding to the outermost layer of the plate (200) (e.g., the layer disposed on the outermost side of the secondary battery module and the layer disposed on the innermost side) may be configured to have electrical insulation properties.

[0066] For example, the first layer (200) may include a fiber-reinforced plastic having non-conductive properties (insulating performance), such as glass fiber, basalt fiber, aramid fiber, etc.

[0067] In particular, in one embodiment, the first layer (220) may include a plurality of detailed fiber layers. In this case, the detailed fiber layers may be arranged so that the arrangement directions of the yarns constituting each detailed fiber layer are combined with each other to form an overall radial structure.

[0068] Since the first layer (220) is positioned on the outer side of the plate (200), it may have the greatest need to be protected from physical external force. In addition to the above-mentioned physical external force, it may also need to withstand internal pressure generated within the frame of the secondary battery module. Therefore, if each first layer (220) (e.g., the first-first layer (220a) and the first-second layer (220b)) is configured so that each detailed fiber layer has an overall radial structure, the possibility of damage to the plate (200) can be minimized in response to each direction regardless of the direction of the external force acting on the plate (200).

[0069] Meanwhile, for example, when the principal stress direction of a secondary battery module (e.g., the first direction corresponding to the direction with the highest specific gravity among the stresses acting on the module frame (130) under a normal use environment of the secondary battery module (e.g., the direction illustrated by arrow "1" in FIGS. 3 and 4a)) and the non-stress direction of the secondary battery module (e.g., the second direction corresponding to the direction with the second highest specific gravity among the stresses acting on the module frame (130) under a normal use environment of the secondary battery module) (e.g., the direction perpendicular to each of the first directions in a plane parallel to each plate (200) of the module frame (130), e.g., the direction illustrated by arrow "2" in FIGS. 3 and 4a)) are set to two axes of 0 degrees and 90 degrees, respectively, "0 degrees" (-180 degrees) (i.e., the principal stress direction of the module), "90 degrees" (-90 degrees) (i.e., the non-stress direction of the module), The first layer (220) may be configured in such a manner that either the direction of "45 degrees" (-135 degrees) or "135 degrees" (-45 degrees) is the longitudinal direction of the yarn of each detailed fiber layer, and these detailed fiber layers are laminated to form one fiber layer (e.g., the 1st layer (220a) or the 1st layer (220b)) having a radial structure. Meanwhile, the principal stress direction of the secondary battery module may be a direction other than the direction of the arrow "1" illustrated in FIGS. 3 and 4a (e.g., the direction illustrated by the arrow "2" illustrated in FIGS. 3 and 4a) based on the direction in which the battery cells (110) are arranged on the inside of the module frame (130).

[0070] Meanwhile, according to various embodiments of the present disclosure, the module frame (130) can be configured to have the same symmetrical structure when viewed from either the inner or outer direction of the secondary battery module based on the layered cross-section of the plate (200).

[0071] For example, when the 1st layer (220a), which is the outermost layer of the plate (200), is formed in a form in which a first detailed fiber layer is arranged so that the "0 degree" (-180 degree) direction (i.e., the principal stress direction of the module) is in the longitudinal direction of the yarn, a second detailed fiber layer is arranged so that the "45 degree" (-135 degree) direction is in the longitudinal direction of the yarn, and a third detailed fiber layer is arranged so that the "135 degree" (-45 degree) direction is in the longitudinal direction of the yarn, based on either the inner side to the outer side or the outer side to the inner side of a specific plate (200), the 1st layer (220a), which is the innermost layer of the plate (200), is formed in a form in which the third detailed fiber layer, the second detailed fiber layer, and the first detailed fiber layer are sequentially laminated, thereby implementing a symmetrical structure of the plate (200).

[0072] Meanwhile, the first layer (220) may be configured to include detailed fiber layers arranged to face "30 degrees" (-150 degrees) or "60 degrees" (-120 degrees) in addition to the directions of "0 degrees", "90 degrees", "45 degrees", and "135 degrees" described above as a radial structure, and various other radial structures not mentioned above may be considered. Through this, in the module frame (130) according to various embodiments of the present disclosure, the stress acting on the first layer (220) of each plate (200) may be distributed in various directions to secure structural stability.

[0073] Meanwhile, in the case of manufacturing a module frame (130) using metal as in the past, it was necessary to perform an insulating coating on at least some of the surfaces facing the cells (110) (or cell stacks) or to directly perform the insulating coating work on the outer surface of the cells (110) (or cell stacks). However, in the module frame (130) according to various embodiments of the present disclosure, since each outermost layer of the plate (200) can have insulating performance, the insulating coating work on the outer surface of the module frame (130) or the insulating coating work on the outer surface of the cells (110) that was performed in the past can be omitted.

[0074] Next, the second layer (240) is a layer interposed 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 may correspond to a layer having superior mechanical strength properties (e.g., tensile strength) or rigidity properties than the other layers.

[0075] For example, the first layer (220) and the second layer (240) may differ depending on the difference in the number of fiber bundles constituting each layer. The distinction between the first layer (220) and the second layer (240) may be based on the target strength or stiffness characteristics, for example, the first layer (220) may have a stiffness less than or equal to that of an aluminum alloy, and the second layer (240) may have a stiffness greater than that of an aluminum alloy.

[0076] In an embodiment, the second layer (240) may be defined as a layer in which the number of yarns (or the number of detailed fiber layers) arranged such that the first direction (the 0 degree direction described above) corresponding to the principal stress direction of the secondary battery module (100) (e.g., the direction illustrated by arrow "1" in FIG. 3) is the longitudinal direction of the yarns is greater than the number of yarns (or the number of detailed fiber layers) arranged in any other direction. As a result, mechanical rigidity with respect to the principal stress direction of the module may be secured in the second layer (240). For example, the number of yarns (or the number of detailed fiber layers) corresponding to the principal stress direction may have a ratio of about 50% or more to the total number of yarns (or the total number of detailed fiber layers) of the second layer (240).

[0077] 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 detailed fiber layer composed of carbon fibers arranged such that the first direction (i.e., the principal stress direction of the module (100)) is the longitudinal direction of the carbon fiber yarn.

[0078] However, the present invention is not limited to such embodiments. For example, in another embodiment, the second layer (240) may not include a detailed fiber layer composed of carbon fibers, but instead may be composed of a fiber layer composed of glass fibers arranged such that the first direction is the longitudinal direction of the yarns, and the yarn density of the detailed fiber layer may be greater than the yarn density of the detailed fiber layers of other layers (e.g., the detailed fiber layer composed of glass fibers of the first layer (220). In this case, there may be an advantage in that the second layer (240) can be formed by securing a certain level of rigidity or higher without using expensive carbon fibers.

[0079] In an embodiment, the second layer (240) may also include multiple detailed fiber layers, similar to the first layer (220).

[0080] For example, the second layer (240) may include a detailed fiber layer in which yarns are arranged to face a first direction (e.g., a direction illustrated by arrow "1" in FIGS. 3 and 4B), which is a principal stress direction of the module. In addition, the second layer (240) may further include a detailed fiber layer in which yarns are arranged to face a non-stress direction of the module (i.e., a second direction perpendicular to the first direction on the plane of the plate (200)) (e.g., a direction illustrated by arrow "2" in FIGS. 3 and 4B). For example, when the second layer (240) includes a detailed fiber layer in which yarns are arranged to face the non-stress direction, the number of detailed fiber layers corresponding to the non-stress direction may be less than or equal to the number of detailed fiber layers corresponding to the principal stress direction.

[0081] Meanwhile, in the case of the second layer (240), the second-first layer (240a) positioned at the top and the second-second layer (240b) positioned at the bottom based on the third layer (260), which is the central layer of the plate (200), may be formed so that each detailed fiber layer is symmetrical with respect to the material, thickness, and / or arrangement of yarns.

[0082] Next, the third layer (260) is a layer positioned in the center of the layered cross-sectional structure of the plate (200), and may correspond to a layer with 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 with a high melting point and low thermal conductivity.

[0083] For example, the third layer (260) may be configured to include at least one of basalt fiber or a metal sheet made of stainless steel.

[0084] In general, when a module frame (130) for a secondary battery is formed of a composite material including fiber-reinforced plastic, it may be more susceptible to thermal runaway phenomenon of the secondary battery compared to a module frame (130) composed only of a conventional metal material. However, in the case of the module frame (130) according to various embodiments of the present disclosure, since a third layer (260) with reinforced fire resistance is provided on the central side, the structural collapse phenomenon of the module frame (130) in a high temperature or high pressure environment can be effectively prevented.

[0085] Meanwhile, in one embodiment, the third layer (260) may be formed with a greater thickness (e.g., about twice the thickness of each of the first layers (220a, 220b) or the second layers (240)) than each of the first layers (220) (e.g., the first-1 layer (220a) or the first-2 layer (220b)) or the second layer (240) (e.g., the second-1 layer (240a) or the second-2 layer (240b)). Alternatively, in other embodiments, each of the layers (e.g., the first-first layer (220a), the second-first layer (240a), the third layer (260), the second-second layer (240b), and the first-second layer (220b)) may be formed to have substantially the same thickness as each other, or may be configured to include the same number of detailed layers (detailed fiber layers or metal sheet layers corresponding to the detailed fiber layers). For example, each of the layers may be configured to include four detailed layers each (or five detailed layers each). In another embodiment, only the second layer (240) (i.e., the second-1 layer (240a) and the second-2 layer (240b)) and the third layer (260) may be configured to include the same thickness or the same number of sublayers, respectively, and the first layer (220) (i.e., the first-1 layer (220a) and the first-2 layer (220b)) related to electrical insulation properties may be configured to include only sublayers having a smaller thickness or a smaller number of sublayers than the second layer (240) or the third layer (260). For example, each of the first layers (220) (220a, 220b) may have a thickness of less than 2 mm, and layers other than the first layer (220) may have a thickness of greater than or equal to 2 mm.

[0086] In addition, in the embodiment, the arrangement direction of the yarns constituting the detailed fiber layer included in the third layer (260) may correspond to the main stress direction (e.g., the first direction (the direction shown by arrow "1" in FIG. 3)) or the stress direction (e.g., the second direction (the direction shown by arrow "2" in FIG. 3)) of the secondary battery module (100). As an example, the number of detailed fiber layers arranged to correspond to the main stress direction among the detailed fiber layers included in the third layer (260) may be equal to or less than the number of detailed fiber layers arranged to correspond to the stress direction. Meanwhile, in another embodiment, the arrangement direction of the yarns constituting the detailed fiber layer included in the third layer (260) may have a direction other than the main stress direction or the stress direction of the secondary battery module (100). For example, the detailed fiber layers included in the third layer (260) may have a radial yarn arrangement.

[0087] In various embodiments, the third layer (260) may be configured to include the aforementioned excellent fire resistance fiber material (basalt fiber) or metal sheet, but as long as the third layer (260) includes such excellent fire resistance material as a detailed layer (a detailed fiber layer or a metal sheet layer corresponding to the detailed fiber layer), another detailed fiber layer composed of a material other than the aforementioned material (e.g., glass fiber, aramid fiber, carbon fiber, etc.) may be further included in the third layer (260). However, in this case, it may be more preferable that the detailed layer formed of the excellent fire resistance fiber material is disposed on the outermost layer of the third layer (260) (i.e., the detailed layer adjacent to the second layer (240) (e.g., the 2-1 layer (240a) and the 2-2 layer (240b)).

[0088] In various embodiments, the plate (200) may have a layered cross-sectional structure that is symmetrical overall in the thickness direction. Furthermore, in one embodiment of the present disclosure, each of the layers constituting the plate (200) (e.g., the first layer (220) (i.e., the first-1 layer (220a) and the first-2 layer (220b)), the second layer (240) (i.e., the second-1 layer (240a) and the second-2 layer (240b)), and the third layer (260) respectively) may also individually have a layered structure that is symmetrical in the thickness direction of the plate (200). In this way, if each layer (e.g., the first layer (220) (220a, 220b), the second layer (240) (240a, 240b), and the third layer (260)) has a symmetrical structure that does not have a specific directionality in the thickness direction, even when the plate (200) is manufactured by pre-manufacturing each layer in a semi-finished form and then bonding them, the vertical direction of each layer does not need to be considered, which can be convenient in the manufacturing process. In addition, since the isotropic property is secured for each layer, the structural stability can be further improved, and there can be an advantage in that the structural stability can be maintained even when the drawing process or the pressing process described later is applied to the plate (200).

[0089] Meanwhile, in another embodiment, the plate (200) has a structure in which the arrangement direction of each yarn is completely symmetrical without a specific directionality in the thickness direction, while each layer constituting the plate (200) (e.g., the first layer (220) (220a, 220b), the second layer (240) (240a, 240b)), the third layer (260)) may be configured such that the sublayers constituting each layer have a structure in which the material and thickness are completely symmetrical in the thickness direction, but the two sublayers have a direction in which the arrangement of yarns is symmetrical with respect to the principal stress direction. For example, when the yarn arrangement direction of the sublayer arranged at the innermost side in one layer has an angular difference of A° from the principal stress direction, the yarn arrangement direction of the sublayer arranged at the outermost side may have an angular difference of 180-A° from the principal stress direction.

[0090] Meanwhile, the module frame (130) according to various embodiments of the present disclosure may be manufactured by using the RTM (resin transfer molding) method, or by using at least one of the heterogeneous injection molding method, the press method, and the drawing method.

[0091] For example, when the module frame (130) is manufactured through a drawing method, the module frame (130) can be manufactured by bending a single plate (200) based on a composite material including a fiber-reinforced plastic according to various embodiments of the present disclosure into a T-shape (or U-shape) and then joining it to another plate.

[0092] In addition, in one example, when the module frame (130) includes at least one flange (131) on the side surface (see FIG. 1b), when 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), but when the module frame (130) is manufactured by the pultrusion method or the like, the flange (131) component made of the material of the plate (200) of the module frame (130) may be formed by bonding it to the side surface 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, when the module frame (130) is manufactured by the pultrusion method, it may be possible to form the flange (131) and the main body of the module frame (130) integrally.

[0093] FIG. 3 is a schematic perspective view for explaining the primary stress direction and secondary stress direction of a secondary battery module (100) in a module frame (130) according to various embodiments of the present disclosure.

[0094] As described above, in FIG. 3, the first direction (direction illustrated by arrow "1") is the direction of the primary stress of the secondary battery module (100), the second direction (direction illustrated by arrow "2") is the direction of the secondary battery module (100), and the third direction (direction illustrated by arrow "3") may be a direction perpendicular to the first and second directions (e.g., the direction of the thickness of each plate (200) constituting the module frame (130).

[0095] For example, the first direction may 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 may correspond to a direction from the first open end (e.g., the front) of the module frame (130) to the second open end (e.g., the rear) (e.g., a direction parallel to the direction in which the electrode tabs of the cell (110) are directed).

[0096] However, this direction setting may be applied differently in consideration of the direction in which the battery cells (110) are arranged within the module frame (130) of the secondary battery module (100). Accordingly, in another example, the second direction (direction indicated by arrow "2") in FIG. 3 may become the principal stress direction of the secondary battery module (100).

[0097] FIG. 4a is a drawing exemplarily showing the radial yarn arrangement direction of each detailed fiber layer constituting the first layer (220), and FIG. 4b is a drawing exemplarily showing the yarn arrangement direction (e.g., the main stress direction (first direction) or the negative stress direction (second direction)) of each detailed fiber layer constituting the second layer (240) (or the third layer (260)).

[0098] For convenience of explanation, the axis corresponding to "0 degrees" in FIGS. 4a and 4b is set as the first direction, which is the main stress direction of the secondary battery module (100), and the axis corresponding to "90 degrees" is set as the second direction, which is the non-stress direction of the secondary battery module (100), as described above with reference to FIG. 2.

[0099] FIG. 5a and FIG. 5b are schematic cross-sectional views and perspective views of a module frame (130) for explaining the main stress direction and the secondary stress direction of the module frame (130) according to the swelling phenomenon of the battery cell (110) in various embodiments of the present disclosure.

[0100] FIG. 6a and FIG. 6b are schematic cross-sectional views and perspective views of a module frame (130) for explaining the main stress direction and the secondary stress direction of the module frame (130) according to the increase in internal pressure of the secondary battery module (100) in various embodiments of the present disclosure.

[0101] Referring to FIGS. 5A and 5B, battery cells (110) (or battery cell stacks) housed inside a module frame (130) in a secondary battery module (100) may be arranged in a row along one direction (e.g., x-axis direction, see FIG. 1, etc.). Meanwhile, when a swelling phenomenon occurs in the battery cells (110) (or battery cell stacks), the cell volume may increase in the direction in which the battery cells (110) are stacked, which may pressurize both sides of the module frame (130) (e.g., closed surfaces of both sides of the module frame (130). Therefore, the module frame (130) may need to absorb and support the resulting pressing force.

[0102] For example, when a swelling phenomenon occurs in a battery cell (110) (or a battery cell stack), an expansion pressure is generated in a direction perpendicular to the main body (the part where the electrode assembly is accommodated) of the battery cell (110) (e.g., the x-axis direction in FIG. 5a), and accordingly, stress may be generated on the side of the module frame (130) in a direction that resists this expansion pressure.

[0103] In particular, referring to FIG. 5a, the expansion pressure of the battery cell (110) (or battery cell stack) may be most greatly applied in each central region based on the height direction (e.g., z-axis direction) of the side surface of the module frame (130), and accordingly, a relatively large tensile force may be generated in the direction perpendicular to the stacking direction (x-axis direction) of the battery cell (110) and the longitudinal direction (y-axis direction) of the battery cell (110) as shown in FIGS. 5a and 5b on the side surface of the module frame (130). That is, due to the swelling phenomenon of the battery cell (110) (or battery cell stack), a relatively large stress in the z-axis direction among stresses in various directions may be generated on the side surface of the module frame (the side closed end of the module frame (130).

[0104] 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 based on the side plane of the module frame (130).

[0105] In addition, 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, so the module frame (130) can receive a large force in the direction parallel to the y-axis from the side (e.g., the end parallel to the yz plane).

[0106] In particular, in the case of a pouch cell with a large aspect ratio, the amount of change in cell volume due to swelling may be large at the center of the battery cell (100) based on the y-axis, so in the module frame (130) according to various embodiments of the present disclosure, the y-axis direction (second direction) perpendicular to the main stress direction is set as the stress direction, and a composite material including a fiber-reinforced plastic having a radial or other yarn arrangement structure applied to the module frame (130) is used, thereby minimizing structural deformation due to the swelling phenomenon.

[0107] Meanwhile, referring to FIGS. 6a and 6b, as the internal pressure of the secondary battery module (100) increases, a swelling phenomenon may occur in the module frame (130), and accordingly, the 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) (the direction of the solid arrow in FIG. 6a).

[0108] According to various embodiments of the present disclosure, the direction of internal pressure action of the secondary battery module (100), the direction of swelling action described with reference to FIGS. 5A and 5B, and the manufacturing method of the module frame (130) including the drawing method, etc., can be comprehensively considered to determine the direction of primary stress and the direction of secondary stress and to determine the direction of arrangement of the yarn.

[0109] For example, in one embodiment of the present disclosure, a first direction parallel to the circumferential direction of a square tubular or U-shaped body of a module frame (130) (e.g., the direction shown by arrow "1" in FIG. 3) is set as a principal stress direction, a longitudinal direction of the body from the first open end of the module frame (130) toward the second open end (e.g., the direction shown by arrow "2" in FIG. 3) is set as a secondary stress direction, and a yarn arrangement direction of each fiber layer constituting the plate (200) is determined correspondingly, thereby providing a module frame (130) having maximized rigidity in consideration of the use and manufacturing method of the module frame (130) for a secondary battery. Alternatively, in another embodiment, based on the arrangement direction of the battery cells (110), another specific direction (e.g., the longitudinal direction of the main body) is set as the principal stress direction, and another specific direction (e.g., a first direction parallel to the circumferential direction of the main body of the module frame (130)) is set as the secondary stress direction, taking the principal stress direction into consideration, so as to determine the yarn arrangement direction of each fiber layer.

[0110] In addition, when forming a module frame (130) with a composite material including fiber-reinforced plastic as in various embodiments of the present disclosure, compared to a case where the module frame (130) is formed with a general metal material, the composite material can have a Young's modulus lower than that of the metal, so that it can have high rigidity capable of responding to swelling of the battery cells (110) while having elastic properties capable of effectively absorbing the swelling, and since it is lighter than the metal, it can have the effect of reducing the weight of the secondary battery and increasing its energy density.

[0111] In addition, the strength, elasticity, and fire resistance of each material can be adjusted differently to meet the needs of various types of secondary batteries, so there is an advantage of greater design freedom compared to a conventional metal material module frame (130).

[0112] While 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 without departing from the technical spirit of the present invention as set forth in the claims. Furthermore, the embodiments described above may be implemented by deleting some components, and the embodiments may be implemented in combination with each other.

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 above secondary battery module housing is formed by a plate based on a composite material including fiber reinforced plastic, The above plate, 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, A secondary battery module housing having a layered cross-sectional structure symmetrical in the thickness direction of the above plate.

2. In paragraph 1, The second layer is provided in multiple numbers, The above plate, A secondary battery module housing, 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. In paragraph 2, Each of the plurality of first layers, each of the plurality of second layers, and the third layer, A module housing for a secondary battery, each comprising a plurality of sublayers having the same number of sublayers.

4. In paragraph 2, Each of the plurality of first layers, each of the plurality of second layers, and the third layer, A module housing for a secondary battery, comprising a plurality of sublayers each having a layered cross-sectional structure symmetrical in the thickness direction.

5. In paragraph 1, Each of the plurality of first layers includes a plurality of detailed fiber layers, A secondary battery module housing, wherein the arrangement direction of the yarns constituting any one of the plurality of detailed fiber layers has a radial structure corresponding to the arrangement direction of the yarns constituting the remaining detailed fiber layers.

6. In paragraph 1, At least one second layer, At least one first detailed fiber layer composed of yarns arranged such that the direction corresponding to the principal stress direction of the plate is the longitudinal direction of the yarns; and At least one second detailed fiber layer composed of yarns arranged such that the direction corresponding to the direction other than the principal stress direction is the longitudinal direction of the yarn, A secondary battery module housing, wherein the number of said at least one first detailed fiber layer of said at least one second layer is greater than the number of said at least one second detailed fiber layer.

7. In paragraph 6, At least one second detailed fiber layer of said at least one second layer A secondary battery module housing, comprising yarns arranged such that the direction corresponding to the stress direction of the above plate is the longitudinal direction of the yarns.

8. In paragraph 7, A secondary battery module housing, wherein the above-mentioned principal stress direction and the above-mentioned secondary stress direction are perpendicular to each other.

9. In paragraph 6, At least one first detailed fiber layer of at least one second layer, Contains carbon fiber, or A secondary battery module housing comprising glass fibers having a density greater than that of yarns constituting at least one second detailed fiber layer of at least one second layer.

10. In paragraph 2, The third layer above is, A module housing for a secondary battery, comprising at least one of a sublayer composed of basalt fibers or a sublayer composed of a metal sheet made of stainless steel.

11. In paragraph 2, A secondary battery module housing, wherein each of the plurality of second layers and the third layer have substantially the same thickness.

12. In paragraph 2, The third layer above is, At least one first detailed layer composed of yarns arranged such that the direction corresponding to the principal stress direction of the plate is the longitudinal direction of the yarns; and At least one second detailed layer composed of yarns arranged such that the direction corresponding to the stress direction of the plate is the longitudinal direction of the yarns, A secondary battery module housing, wherein the number of the at least one first sublayer of the third layer is less than the number of the at least one second sublayer of the third layer.

13. In paragraph 1, The above module housing further comprises a mounting flange positioned at the closed end of the side, A secondary battery module housing, wherein the above mounting flange is formed of the same material as the above plate.

14. In paragraph 1, The above module housing is a module housing for a secondary battery manufactured by RTM method, heterogeneous injection method, press method, or drawing method.

15. In paragraph 1, A secondary battery module housing, 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 above secondary battery module housing is formed by a plate based on a composite material including fiber reinforced plastic, The above plate, A third layer arranged at the center based on the thickness direction cross-section of the above plate; A plurality of first layers arranged on the outer portion based on the thickness direction cross-section of the above plate; and A plurality of second layers are disposed on both sides with the third layer interposed therebetween, and are interposed between the plurality of first layers, The above plurality of first layers are formed of a fiber-reinforced plastic material having electrical insulating properties, The above plurality of second layers have greater mechanical strength than the above plurality of first layers, A module housing for a secondary battery, wherein the third layer comprises at least one of basalt fiber or metal sheet.

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