Patent Publication Number: US-2023155227-A1

Title: Exchangeable split profile battery cell carrier

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of European Patent Application No. 21208140.0, filed in the European Patent Office on Nov. 15, 2021, and Korean Patent Application No. 10-2022-0152037, filed in the Korean Intellectual Property Office on Nov. 14, 2022, the entire content of both of which are incorporated by reference herein. 
     BACKGROUND 
     1. Field 
     Aspects of embodiments of the present disclosure relate to a frame that provides structural support for a battery pack having at least two rows of stacked battery cells, and in particular, to a frame of a battery pack that allows for an easy exchange of an individual row of stacked battery cells. Aspects of embodiments of the present disclosure further relate to a battery pack having at least two rows of stacked battery cells, and to a vehicle that uses a power source including such a battery pack. Aspects of embodiments of the present disclosure further relate to a method of assembling trays of stacked battery cells. 
     2. Description of the Related Art 
     In the recent years, vehicles for transportation of goods and people have been developed using electric power as a source for motion. Such an electric vehicle is an automobile that is propelled by an electric motor that uses energy stored in rechargeable batteries. The electric vehicle may be solely powered by batteries, or may be a form of a hybrid vehicle that is additionally powered by, for example, a gasoline generator. Furthermore, the vehicle may include a combination of an electric motor and a combustion engine. 
     In general, an electric-vehicle battery (EVB) or a traction battery is a battery used to power the propulsion of battery electric vehicles (BEVs). Electric-vehicle batteries may differ from starting, lighting, and ignition batteries, in that they may be designed to give power over sustained periods of time. A rechargeable or secondary battery differs from a primary battery, in that the rechargeable or secondary battery may be repeatedly charged and discharged, while the primary battery may provide only an irreversible conversion of chemical to electrical energy. Low-capacity rechargeable batteries may be used as a power supply for small electronic devices, such as cellular phones, notebook computers, and camcorders, while high-capacity rechargeable batteries may be used as the power supply for electric vehicles, hybrid vehicles, and the like. 
     Typically, rechargeable batteries include an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, a case for receiving the electrode assembly, and an electrode terminal electrically connected to the electrode assembly. An electrolyte solution is injected into the case in order to enable charging and discharging of the battery via an electrochemical reaction of the positive electrode, the negative electrode, and the electrolyte solution. A shape of the case (e.g., cylindrical or rectangular) depends on the battery&#39;s intended purpose. Lithium-ion (and similar lithium polymer) batteries are widely used in laptops and consumer electronics, and dominate the most recent group of electric vehicles in development. 
     The above information disclosed in this Background section is for enhancement of understanding of the background of the present disclosure, and therefore, it may contain information that does not constitute prior art. 
     SUMMARY 
     Rechargeable batteries may be used as a battery module, for example, for motor driving of a hybrid vehicle. The battery module may be formed of a plurality of unit battery cells that are connected in series and/or in parallel, so as to provide high energy density. In other words, the battery module may be formed by interconnecting the electrode terminals of the plurality of unit battery cells depending on a desired amount of power, and in order to realize a high-power rechargeable battery. 
     A battery pack is a set of any suitable number of battery modules that may be identical to each other, but may be different from each other. The battery modules may be configured in a series, parallel, or a mixture of both, to deliver the desired voltage, capacity, and/or power density. Components of the battery pack include the individual battery modules, and the interconnects, which provide electrical conductivity between them. 
     Mechanical integration of such a battery pack may use appropriate mechanical connections between the individual components thereof (e.g., the battery modules, and between the battery modules), and a supporting structure of the vehicle. These connections may remain functional and safe during an average service life of a battery system. Further, installation space and interchangeability requirements may need to be met, especially in mobile applications. 
     Mechanical integration of the battery modules may be achieved by providing a carrier framework, and by positioning the battery modules on the carrier framework. Fixing the battery cells or battery modules may be achieved by fitted depressions in the carrier framework, or by mechanical interconnectors such as bolts or screws. As another example, the battery modules may be confined by fastening side plates to lateral sides of the carrier framework. Further, cover plates may be fixed atop and below the battery modules. 
     The carrier framework of the battery pack may be mounted to a carrying structure of the vehicle. In a case where the battery pack is to be fixed at a bottom of the vehicle, the mechanical connection may be established from the bottom side by, for example, bolts passing through the carrier framework of the battery pack. The carrier framework is typically made of aluminum or an aluminum alloy to lower a total weight of the construction. Hereinafter, the carrier framework for a battery pack may also be referred to as a “frame.” 
     Battery systems according to a comparative example, despite any modular structure, usually includes a battery housing that serves as an enclosure to seal the battery system against an environment (e.g., an external environment), and provides structural protection to the battery system&#39;s components. Housed battery systems are typically mounted as a whole into their application environment (e.g., an electric vehicle or hybrid vehicle). Thus, replacement of defective system parts (e.g., a defective battery submodule) may first require dismounting of the entire battery system, and removal of its housing. Thus, even defects of small and/or cheap system parts may lead to dismounting and replacement of the complete battery system, and the separate repair of the defective parts. As high-capacity battery systems may be expensive, large, and heavy, such procedures may be burdensome, and the storage of the bulky battery systems (e.g., in a mechanic&#39;s workshop) may be difficult. 
     Further, to provide thermal control of the battery pack, a thermal management system may be used to safely operate and use the at least one battery module by efficiently emitting, discharging, and/or dissipating heat generated from the battery module&#39;s rechargeable batteries. When heat emission/discharge/dissipation is not sufficiently performed, temperature deviations occur between respective battery cells, such that the at least one battery module may not generate a desired amount of power. In addition, an increase of the internal temperature may lead to abnormal reactions occurring therein, and thus, charging and discharging performance of the rechargeable batteries may deteriorate, and the life-span of the rechargeable battery may be shortened. Thus, cell cooling for effectively emitting/discharging/dissipating heat from the battery cells may be desired. 
     Typical battery housings and/or frames may employ a certain number of aluminum extrusion profiles, which are used as longitudinal-beams and cross-beams, in order to achieve a rigid mechanical structure. Such aluminum extrusion profiles may also be used for the main support, and for cooling of the battery cells as well. Due to constant pressure for reducing overall costs and package space, the battery cells may typically be integrated as a so called “battery cell stack” directly between the “beams,” such as the aluminum extrusion profiles. Therefore, the battery cells may be joined (e.g., directly joined) to the beams (e.g., the carriers, the profiles, and the like) via a structural adhesive material. 
     Irrespective of whether the above-described stack-arrangements (e.g., the battery cell stacks) are separated by using one, two, or more beams, the number of beams used may be a compromise (e.g., a trade-off) in terms of the amount of required parts, manufacturing costs, package, safety, and possibility of a rework. 
     According to one or more embodiments of the present disclosure, a battery pack, and a frame for the battery pack, having one or more improved characteristics (e.g., amount of required parts, manufacturing costs, package, safety, and/or the possibility of a rework) when compared to those of the comparative example described above may be provided. 
     For example, in some embodiments, the battery pack, and the frame for the battery pack, may include two cost effective, very simple kinds of extrusion profiles (e.g., sub-beams), which may be easy to manufacture. 
     In some embodiments, a risk of a thermal propagation between two battery cell stacks at the same package space may be reduced. 
     In some embodiments, cooling means (e.g., as part of the thermal management system) may be implemented within the beams. 
     In some embodiments, a rigid connection between two sub-beams may be provided, such that the connected sub-beams may be considered as one single profile (e.g., one single beam). 
     In some embodiments, the battery pack, and the frame for the battery pack, may enable a total exchange of a battery cell stack, even in a case where the battery cells are glued/adhered directly to the profiles. 
     In some embodiments, the battery pack, and the frame for the battery pack, may allow for various flexibility, and in particular, may allow for the combination of various different types of beams (e.g., profiles), for example, such as beams that are especially adapted as a front-end beam and/or a rear-end beam (e.g., that are equipped with interfaces, sealing flanges, and/or the like), to be installed. 
     Accordingly, a very cost-effective battery/frame may be provided having higher safety performance at the same package space. Further, in a case of a failure occurring within a battery cell stack, in some embodiments, it may be possible to exchange the affected stack, even when the cells are glued to the beams (e.g., the profiles). 
     According to one or more embodiments of the present disclosure, a frame for providing structural support for a battery pack having at least two rows of stacked battery cells is provided. 
     According to one or more embodiments, the frame includes: a first end beam, a second end beam, and one or more intermediate beams. The beams may be arranged in parallel or substantially in parallel to each other on a virtual plane. The one or more intermediate beams are arranged between the first end beam and the second end beam, and each of the beams is orientated along a first direction. Each of the beams includes: a first plate having a first side, and a second side opposite to the first side of the first plate; a second plate having a first side, and a second side opposite to the first side of the second plate; and a coupling means for slidably connecting the second side of the first plate to the second side of the second plate, such that any displacement of the first plate relative to the second plate is inhibited, except for a shifting the first plate relative to the second plate in or against a suitable direction (e.g., a predefined or predetermined direction). 
     It should be noted that for one assembled beam (e.g., a beam with the respective first and second plates being connected to each other), the inner sides of the plates are labelled as the second sides, and the outer sides are labelled as the first sides. 
     According to one or more embodiments of the present disclosure a battery pack is provided. 
     According to one or more embodiments of the present disclosure, the battery pack includes at least two rows of stacked battery cells, and the frame. A number of intermediate beams included therein equals the number of rows of stacked battery cells minus one. Each of the rows of stacked battery cells is mounted between a pair of adjacent beams. Here, the term “beam” refers to any one of the first end beam, the second end beam, and the intermediate beams. The expression a “row of stacked battery cells being mounted between a pair of adjacent beams” refer, in particular, to the row of stacked battery cells that is held in place by any one of the adjacent beams. This may be performed simply by mechanical structures (e.g., using flanges) or by other methods as described in more detail below. 
     In an embodiment, the rows of stacked battery cells may each be mounted to the respective adjacent beams using adhesives. 
     According to one or more embodiments of the present disclosure, a vehicle using a power source comprising the battery pack is provided. 
     According to one or more embodiments of the present disclosure, a method of assembling trays of stacked battery cells for use in a battery pack is provided. 
     According to one or more embodiments of the present disclosure, the method includes: a1) providing at least two rows of stacked battery cells; a2) providing a first and second plate of a first end beam; a3) providing a first and second plate of a second end beam; and a4) providing a number of first plates of an intermediate beam and a number of second plates of an intermediate beam. 
     The number of first plates of an intermediate beam and the number of second plates of an intermediate beam may be equal to each other, and may be equal to the of rows of stacked battery cells minus one. Here, each of the plates has a first side and a second side. The first and second plate of the first end beam are configured for being connected (e.g., coupled or attached) to each other, with their respective second sides, to form the first end beam. The connecting inhibits any displacement of the respective first plate relative to the respective second plate, except for a shifting of the respective first plate relative to the respective second plate in or against a direction of the first end beam. 
     The first and second plates of the second end beam are configured for being connected (e.g., coupled or attached) to each other, with their respective second sides, to form the second end beam. The connecting inhibits any displacement of the respective first plate relative to the respective second plate, except for a shifting of the respective first plate relative to the respective second plate in or against a direction of the second end beam. Each of the first plates of an intermediate beam is configured for being connected (e.g., coupled or attached) with each of the second plates of an intermediate beam to form an intermediate beam. The second side of the respective first plate is connected (e.g., coupled or attached) to the second side of the respective second plate. The connecting inhibits any displacement of the respective first plate relative to the respective second plate, except for a shifting of the respective first plate relative to the respective second plate in or against a direction of the intermediate beam formed by the respective first and second plates. 
     In an embodiment, the method further includes: b) creating a first end tray by mounting one of the rows of stacked battery cells between the first side of the second plate of the first end beam and the first side of the first plate of an intermediate beam; c) creating a second end tray by mounting a further one of the rows of stacked battery cells between the first side of the second plate of an intermediate beam and the first side of the first plate of the second end beam; d) when the number of rows of stacked battery cells is larger than two: creating, for each of the remaining rows of stacked battery cells, an intermediate tray by mounting each of the rows of stacked battery cells, except for the rows of stacked battery cells that are already mounted in steps b and c, between the first side of the second plate of an intermediate beam and the first side of a first plate of a further intermediate beam. 
     According to one or more embodiments of the present disclosure, a method for assembling a battery pack with a frame is provided. 
     According to one or more embodiments of the present disclosure, the method includes: e) generating trays of stacked battery cells using the method described above; f) assembling the first end beam by connecting (e.g., coupling or attaching) the second side of the first plate of the first end beam with the second side of the second plate of the first end beam; g) assembling the second end beam by connecting (e.g., coupling or attaching) the second side of the first plate of the second end beam with the second side of the second plate of the second end beam; and h) when the number of rows of stacked battery cells equals two: connecting the first end tray with the second end tray by assembling the intermediate beam by connecting (e.g., by coupling or attaching) the respective second sides of the first and second plate of the intermediate beam to each other. 
     In an embodiment, the method may further include i) when the number of rows of stacked battery cells is larger than two: i1) connecting the first end tray with an intermediate tray by assembling an intermediate beam by connecting (e.g., coupling or attaching) the second side of the uncoupled first plate of the intermediate beam used in the first end tray with the second side of the second plate used in one of the intermediate trays; i2) when there is a further unconnected intermediate tray, connecting the further unconnected tray by assembling an intermediate beam by connecting (e.g., coupling or attaching) the second side of the uncoupled first plate of an intermediate beam used in the intermediate tray connected in the foregoing sub-step i1 to the second side of the second plate of an intermediate beam used in the further intermediate tray; i3) repeating sub-step i2 until there is no further unconnected intermediate tray; and i4) connecting the second end tray by assembling an intermediate beam by connecting (e.g., coupling or attaching) the second side of the uncoupled first plate of an intermediate beam used in the intermediate tray, which has been connected last in the foregoing sub-step i1 or i2, to the second side of the second plate of the intermediate beam used in the second end tray. 
     Accordingly, in one or more embodiments of the present disclosure, one or more of the following may be improved. 
     Decomposability: The trend is to glue battery cells directly to the cell frame (e.g., no more modules), and thus, it may be difficult to decompose the pack. However, according to one or more embodiments of the present disclosure, a row of stacked battery cells may include two “profile halves” (e.g., plates), each to the left and right of the battery cells, and thus, may be pulled out of the battery pack from the side. 
     Safety: Because there may be a minimum or reduced material connection between the two “profile halves” (e.g., the first and second plates), heat transfer may be reduced significantly. Consequently, thermal propagation between adjacent cell rows may be prevented or largely reduced. 
     Identical or substantially identical parts: In each profile (e.g., beam), the “profile halves” (e.g., plates) facing the battery cells may be the same kind of component as each other. The remaining “profile half” may then be selected depending on the installation location (e.g., either an “outer half” for establishing an exterior side of the total battery pack or an “inner half” facing the battery cells), when the beam is arranged between two rows of stacked battery cells. 
     However, the aspects and features of the present disclosure are not limited to those described above, and addition aspects and features of the present disclosure may be realized from the following detailed description, figures, and claims and their equivalents, or may be learned by practicing one or more of the presented embodiments of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the present disclosure will be more clearly understood from the following detailed description of the illustrative, non-limiting embodiments with reference to the accompanying drawings, in which: 
         FIG.  1    illustrates a schematic cross-sectional view of an intermediate beam of a frame according to an embodiment of the present disclosure; 
         FIG.  2    schematically illustrates three perspective views (A), (B), and (C) of a first plate and a second plate to be assembled into an intermediate beam according to one or more embodiments of the present disclosure; 
         FIG.  3    illustrates an enlarged view of a cut-out of  FIG.  1   , and a schematic view of a dovetail joint; 
         FIG.  4    schematically illustrates different kinds of plates to be used in the frame according to one or more embodiments of the present disclosure; 
         FIG.  5    schematically illustrates different kinds of beams using combinations of the plates shown in  FIG.  4   ; 
         FIG.  6    schematically illustrates a battery pack according to an embodiment of the present disclosure; 
         FIG.  7    schematically illustrates a split beam of the battery pack shown in  FIG.  6   ; 
         FIG.  8    schematically illustrates a battery pack according to another embodiment of the present disclosure; 
         FIG.  9    schematically illustrates heat insulation provided by a beam of the frame according to one or more embodiments of the present disclosure; 
         FIG.  10    schematically illustrates adhesive layers used to glue battery cells to a beam of the frame according to one or more embodiments of the present disclosure; 
         FIG.  11    schematically shows an example of a coupling means according to an embodiment of the present disclosure; 
         FIG.  12    schematically shows an example of a coupling means according to another embodiment of the present disclosure; and 
         FIG.  13    schematically shows an example of a coupling means according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments will be described in more detail with reference to the accompanying drawings, in which like reference numbers refer to like elements throughout. The present disclosure, however, may be embodied in various different forms, and should not be construed as being limited to only the illustrated embodiments herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art. Accordingly, processes, elements, and techniques that are not necessary to those having ordinary skill in the art for a complete understanding of the aspects and features of the present disclosure may not be described. Unless otherwise noted, like reference numerals denote like elements throughout the attached drawings and the written description, and thus, redundant description thereof may not be repeated. 
     When a certain embodiment may be implemented differently, a specific process order may be different from the described order. For example, two consecutively described processes may be performed at the same or substantially at the same time, or may be performed in an order opposite to the described order. 
     In the following, the terms “upper” and “lower” are defined with respect to the orientation of the illustrated subject-matter in the figures. If a Cartesian coordinate system is shown in a figure, the terms “upper” and “lower” are defined with respect to the x-axis of the coordinate system. For example, the upper cover is positioned at the upper part of the x-axis, whereas the lower cover is positioned at the lower part thereof. 
     In the drawings, the relative sizes of elements, layers, and regions may be exaggerated and/or simplified for clarity. Spatially relative terms, such as “beneath,” “below,” “lower,” “under,” “above,” “upper,” and the like, may be used herein for ease of explanation to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or in operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” or “under” other elements or features would then be oriented “above” the other elements or features. Thus, the example terms “below” and “under” can encompass both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should be interpreted accordingly. 
     In the figures, the x-axis, the y-axis, and the z-axis are not limited to three axes of the rectangular coordinate system, and may be interpreted in a broader sense. For example, the x-axis, the y-axis, and the z-axis may be perpendicular to or substantially perpendicular to one another, or may represent different directions from each other that are not perpendicular to one another. 
     It will be understood that, although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section described below could be termed a second element, component, region, layer or section, without departing from the spirit and scope of the present disclosure. 
     It will be understood that the terms “include,” “comprise,” “including,” or “comprising” specify a property, a region, a fixed number, a step, a process, an element, a component, and a combination thereof, but do not exclude other properties, regions, fixed numbers, steps, processes, elements, components, and combinations thereof. It will be further understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it can be directly on, connected to, or coupled to the other element or layer, or one or more intervening elements or layers may be present. Similarly, when a layer, an area, or an element is referred to as being “electrically connected” to another layer, area, or element, it may be directly electrically connected to the other layer, area, or element, and/or may be indirectly electrically connected with one or more intervening layers, areas, or elements therebetween. In addition, it will also be understood that when an element or layer is referred to as being “between” two elements or layers, it can be the only element or layer between the two elements or layers, or one or more intervening elements or layers may also be present. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” “including,” “has,” “have,” and “having,” when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. For example, the expression “A and/or B” denotes A, B, or A and B. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression “at least one of a, b, or c,” “at least one of a, b, and c,” and “at least one selected from the group consisting of a, b, and c” indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. 
     As used herein, the term “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art. Further, if the term “substantially” is used in combination with a feature that could be expressed using a numeric value, the term “substantially” denotes a range of +/— 5% of the value centered on the value. The use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.” As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. Also, the term “exemplary” is intended to refer to an example or illustration. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification, and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein. 
     According to one or more embodiments of the present disclosure, an improved frame for providing structural support for a battery pack having at least two rows of stacked battery cells is provided. For example, in some embodiments, the frame may include a split-profile, such that the compromise (or trade-off) between the characteristics described above (e.g., the amount of required parts, manufacturing costs, package, safety, and/or the possibility of a rework) may be reduced. 
     As used herein, the expression “structural support” in particular refers to providing a suitable mechanical support, such that a supported member (e.g., the rows of battery stacks and/or each individual battery cell) are held in an essentially fixated geometrical position relative to each other. Here, the term “essentially” includes small changes in the geometry due to normal temperature changes, and changing mechanical loads exerted from the outside onto the frame may remain possible. 
     The phrase “row of stacked battery cells” denotes a row of battery cells, which may include battery cells having the same or substantially the same shape as each other, that are aligned along a suitable direction (e.g., a certain direction), one after the other or one on top of the other, so as to form one or more battery cell stacks. When the row of stacked battery cells include only a single stack, then the row of stacked battery cells may refer to the stack. However, when the row includes more than one battery cell stack, the battery cell stacks themselves may be stacked together in a direction perpendicular to or substantially perpendicular to a direction of the cell stacking in each of the individual cell stacks. Then the stack of battery cell stacks forms the “row of stacked battery cell stacks,” and the orientation of the cell stacking is defined as the orientation of the cell stacking in each of the individual cell stacks (which are oriented in parallel or substantially in parallel relative to each other in such a row). 
     Typically, the individual battery cells may have a prismatic shape. For example, the body of the cell may extend between two parallel bases (e.g., a ground base and a top base), and the two bases may be identically or substantially identically shaped (e.g., as a polygon, or as a circle or an ellipse). Then, the cells may be stacked simply by taking one of the cells and putting the ground base of any further cell on the top base thereof (e.g., of the preceding cell). Further, the battery cells may each be shaped as a right prism (e.g., a prism with a side face being perpendicular to or substantially perpendicular to each of the bases). In a battery pack, more than one row of stacked battery cells may be used. 
     In an embodiment, a coupling means of each of the beams of the frame may include: a first guiding means including one or more first guide rails; and a second guiding means including one or more second guide rails. Each of the first guide rails is fixedly arranged on the surface of the second side of the respective first plate, and extends linearly along a suitable direction (e.g., a predefined direction). Each of the second guide rails is fixedly arranged on the surface of the second side of the respective second plate, and extends linearly along the suitable direction (e.g., predefined direction). At least one of the first guide rails and at least one of the second guide rails are engaged with each other. 
     For example, for each of the coupling means, the number of first guide rails corresponds to the number of second guide rails. In such a case, each of the first guide rails on the respective first plate may be engaged with a matching one of the second guide rails. In some embodiments, however, the number of guide rails provided on the first plate of a beam may be different from the number of guide rails provided on the second plate of that beam. For example, different prefabricated plates may be used together, and there may be a first kind of pairs of first and second plates, each having two guide rails, and a second kind (e.g., a further kind) of pairs of first and second plates, each having only one guide rail. However, the positions of the guide rails on the plates may be chosen such that, for example, the first plate of the first kind is connectable to the second plate of the second kind, in that only one of the guide rails of the first plate becomes engaged with the single guide rail of the second plate. In the latter example, the other guide rail of the first plate may be unused. In an embodiment, for each of the coupling means, the number of the first guide rails is at least two, and the number of the second guide rails is at least two. 
     Each of the guide rails may be formed integrally (e.g., as one piece of material) with the respective plate on which the guide rail is arranged. Then, the plate together with the coupling means arranged thereon may be manufactured by extrusion. The material of some or each of the plates may include (e.g., may be) aluminum (Al). In this case, some or each of the plates may be manufactured as aluminum extrusion profiles. 
     In an embodiment, at least one pair of a first guide rail and a second guide rail that are engaged with each other may have the following properties. The first guide rail may exhibit a first cross-sectional profile in any suitable plane that is perpendicular to or substantially perpendicular to the predefined direction, and crossing (e.g., intersecting) the first guide rail, independent from the position of the plane with respect to the predefined direction. The second guide rail may exhibit a second cross-sectional profile in any suitable plane that is perpendicular to or substantially perpendicular to the predefined direction, and crossing (e.g., intersecting) the second guiding means, independent from the position of the plane with respect to the predefined direction. Further, either a shape of the first cross-sectional profile comprises a cavity with an opening and the second cross-sectional profile comprises a bulge fitting into the cavity, or the shape of the second cross-sectional profile comprises a cavity with an opening and the first cross-sectional profile comprises a bulge fitting into the cavity. In either case, the bulge is connected to the remaining first or second cross-section profile by a connection part passing through the opening of the cavity, and the bulge may have a size that is too large to be passed through the opening of the cavity. 
     In an embodiment, the coupling means of at least one of the beams may include at least one pair of a first guide rail and a second guide rail, the first guide rail and the second guide rail being engaged with each other using a dovetail joint. 
     In an embodiment, for each beam, one or more cooling channels may be arranged on the surface of the second side of the respective first plate. In an embodiment, for each beam, one or more cooling channels are arranged on the surface of the second side of the respective second plate. The cooling channels may be formed integrally with the respective plates on which they are arranged. In some embodiments, each of cooling channels extends linearly along the predefined direction. Then, some or each of the plates together with the respective coupling means and cooling channels may be manufactured by extrusion. 
     In an embodiment, for each of the intermediate beams, the first side of the respective first plate may be configured to provide support for a lateral side of a row of stacked battery cells, and the first side of the respective second plate may be configured to provide support for a lateral side of a further row of stacked battery cells. For the first end beam, the first side of the respective second plate may be adapted to provide support for a lateral side of a row of stacked battery cells. For the second end beam, the first side of the respective first plate may be adapted to provide support for a lateral side of a row of stacked battery cells. 
     In this context, the term “lateral side” of a row of stacked battery cells denotes a side of the row, which extends parallel to or substantially parallel to the direction in which the battery cells are stacked to form the row of stacked battery cells. Accordingly, the side face(s) of a row of stacked battery cells depends on the given shape of the battery cells that are stacked together to form the row of stacked battery cells. For example, if the individual battery cells each exhibit a cuboidal shape, the four side faces of the row of stacked battery cells each have a rectangular planer shape. In this case, the first sides of plates configured to provide support for a lateral side of a row of stacked battery cells may likewise exhibit a planar rectangular shape or a planer trapezoidal shape. However, if some side faces of the battery cells have a convex shape (e.g., if the cross-section of the cells resembles two lying letters “U” with their open sides put together), the first sides of plates configured to provide support for a lateral side of a row of stacked battery cells may have a complementary concave shape. 
     In an embodiment, for each of the intermediate beams, the first side of the respective first plate may be configured to provide support for each of a lateral side of a first row and a second row of stacked battery cells, and the first side of the respective second plate may be configured to provide support for each of a lateral side of the second row and a third row of stacked battery cells. For the first end beam, the first side of the respective second plate may be configured to provide support for a lateral side of the first row of stacked battery cells, and for the second end beam, the first side of the respective first plate may be configured to provide support for a lateral side of the third row of stacked battery cells. 
     In one or more embodiments, the support provided for lateral sides of a row of stacked battery cells by a first side of a plate may be realized by at least one flange. In an embodiment, the number of flanges arranged on that first side may be two. In this case, the flanges may be arranged on either edge of the first side along the predefined direction. Also, the two flanges may have a suitable distance between each other, which encompasses a lateral side of a row of stacked battery cells. 
     In an embodiment, for each of the beams, the surface of the second side of the first plate may have essentially a trapezoidal shape extending between two parallel edges, each being orientated along the predefined direction. Further, for each of the beams, the surface of the second side of the second plate may have essentially a trapezoidal shape extending between two parallel edges, each being orientated along the predefined direction. The trapezoidal shape may be, in particular, a rectangular shape. However, for example, to facilitate a mounting of the beams to front and rear bars oriented perpendicular to or substantially perpendicular to the predefined direction, and configured to hold each of the first end beam, the second end beam, and the intermediate beams in predefined positions (which will be described in more detail below), the rectangular shape of the plates may be prolonged at their respective ends in or against the predefined direction, so as to form mounting areas or the like, which may result in essentially the trapezoidal shape. 
     In an embodiment, for the first end beam, the first side of the respective first plate may be adapted for being mounted to predefined external structures. In an embodiment, for the second end beam, the first side of the respective second plate may be adapted for being mounted to predefined external structures. The predefined external structures may be, for example, parts of a housing configured to accommodate the frame, or parts of a rack configured to store several battery packs using the frame. 
     In an embodiment, the frame may further include a front bar. The front bar may be oriented perpendicular to or substantially perpendicular to the predefined direction, and may be configured to be mechanically connected to each of the respective proximal ends of the first end beam, the second end beam, and each of the intermediate beams, when viewed in the predefined direction. In an embodiment, the frame may further include a rear bar. The rear bar may be oriented perpendicular to or substantially perpendicular to the predefined direction, and may be configured to be mechanically connected to each of the respective distal ends of the first end beam, the second end beam, and each of the intermediate beams, when viewed in the predefined direction. Here, the term “proximal end” of the first end beam, the second end beam and each of the intermediate beams denotes an end of the respective beam that points into a direction opposite to (e.g., against) the predefined direction. Also, the term “distal end” of the first end beam, the second end beam, and each of the intermediate beams denotes an end of the respective beam that points into the predefined direction. The front and/or the rear bar may allow for holding each of the first end beam, the second end beam, and the intermediate beams in respective predefined positions. When using the front bar and the rear bar together in one frame, the front bar and the rear bar may be arranged to be parallel to or substantially parallel to each other. 
     The mounting of any one of the first end beam, the second end beam, and each of the intermediate beams to the front bar may be performed using a suitable connection (e.g., a screw joint or bolted connection) between the front bar and the respective first plate and/or the respective second plate. The mounting of any one of the first end beam, the second end beam, and each of the intermediate beams to the rear bar may be performed using a suitable connection (e.g., a screw joint or bolted connection) between the rear bar and the respective first plate and/or the respective second plate. 
     In one or more embodiments, mechanical structures such as holes for accommodating screws or bolts may be formed in at least some of the plates to facilitate the connecting procedure between a beam and a bar. In some embodiments, each of these mechanical structures may be arranged on the surface of a second side of the respective plate on which it is arranged. Each or of these mechanical structures may be formed integrally with the respective plates onto which it is arranged. In one or more embodiments, these mechanical structures may be realized by through-hole channels linearly extending along the predefined direction, and may be formed integrally with at least some of the plates. In one or more embodiments, plates including the through-hole channels may be manufactured by extrusion techniques. 
     In one or more embodiments, the first end beam, the second end beam, and each of the intermediate beams may be mounted to the front bar and/or the rear bar with the following orientations. The first side of the second plate of the first end beam faces the adjacent intermediate beam. The first side of the first plate of the intermediate beam adjacent to the first end beam faces the first end beam. The first side of the first plate of each intermediate beam faces the first side of the second plate of an adjacent beam being oriented in parallel to or substantially in parallel to that intermediate beam. The first side of the second plate of each intermediate beam faces the first side of the first plate of an adjacent beam oriented in parallel to or substantially in parallel to that intermediate beam. Finally, the first side of the first plate of the second end beam faces the first side of the second plate of the adjacent intermediate beam. As used herein, the expression “faces” may consider the members of the frame, independent from whether or not rows of stacked battery cells are mounted into the frame. 
     The above and other aspects and features of the present disclosure will now be described in more detail hereinafter with reference to the figures. 
       FIG.  1    illustrates a schematic cross-sectional view of an intermediate beam  10  of a frame according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , the intermediate beam  10  includes a first plate  11  (e.g., on the left side in the figure), and a second plate  12  (e.g., on the right side in the figure). Both plates  11 ,  12  have a rectangular or substantially rectangular shape (e.g., an essentially rectangular shape) extending perpendicular to or substantially perpendicular to the drawing plane of the figure. In the following, sides of the first and second plates, which form the exterior of the intermediate beam  10 , will be described as the “first sides” of the respective plates, and sides of the first and second plates, which face each other, will be described as the “second sides” of the respective plates. In other words, in the figure, the left side of the first plate  11  is the first side  111  of the first plate  11 , and the right side of the first plate  11  is the second side  112  of the first plate  11 . Similarly, the right side of second plate  12  is the first side  121  of the second plate  12 , and the left side of second plate  12  is the second side  122  of the second plate  12 . 
     The first plate  11  and the second plate  12  are connected to (e.g., coupled to or attached to) each other by a coupling means, which is shown in the example of  FIG.  1    as being formed by (e.g., as being built by) two pairs of guide rails, each of the pairs of guide rails establishing a connection realized by a so-called dovetail joint. The dovetail joint establishes a connection by engaging a linearly extending groove (as one guide rail) with a likewise linearly extending tongue (as another guide rail). This is described in more detail below with reference to  FIG.  3   , and in particular, with regards to the shape of the guide rails. In an embodiment, an upper dovetail joint is realized by groove  21  and tongue  32  (e.g., the tongue  32  being split into a V-like shape), both of which extend linearly in a direction perpendicular to or substantially perpendicular to the drawing plane of the figure. For example, the groove  21  is arranged on the second side  112  of the first plate  11 , and the matching tongue  32  is arranged at an opposite position to the groove  21  on the second side  122  of the second plate  12 . A lower dovetail joint has the same or substantially the same structure, but in a reversed order with respect to the plates (e.g., a groove  22  thereof is arranged on the second side  122  of second plate  12 , and a tongue  31  thereof is arranged on the second side  112  of first plate  11 ). 
     In some embodiments, the groove  21  may not be directly arranged on the second side  112  of the first plate  11 , but may be fixated to a structure formed by a circumferential wall of a through-hole  51  together with a reinforcing strut  71 . Both the circumferential wall of the through-hole  51  and the reinforcing strut  71  may be arranged directly on the second side  112  of the first plate  11 . Likewise, the groove  22  may not be directly arranged on the second side  122  of the second plate  12 , but may be fixated to a structure formed by a circumferential wall of a through-hole  52  together with a reinforcing strut  72 . Both the circumferential wall of the through-hole  52  and the reinforcing strut  72  may be arranged directly on the second side  122  of the second plate  12 . The through-holes  51  and  52  may accommodate screws or bolts used for fixating the intermediate beam  10  to a front bar  92  or a rear bar  94 , as described in more detail below with reference to  FIG.  8   . 
     Also, arranged on the second sides  112 ,  122  of the plates  11 ,  12  are first and second cooling channels  41 ,  42 , respectively. The cooling channels  41 ,  42  may be arranged directly on the respective plates  11 ,  12 , such that battery cells of a battery pack mounted adjacent to the first sides  111 ,  121  of the plates  11 ,  12  are separated from coolant fluids flowing through the cooling channels  41 ,  42  by a relatively thin material layer of the first plate  11  and the second plate  12 , respectively. Thus, a maximum or increased exchange between the battery cells and the coolant fluids may be achieved (e.g., a maximum or increased cooling effect is acquired). In the example of the intermediate beam  10  shown in  FIG.  1   , the first cooling channel  41  that is arranged on the second side  112  of the first plate  11  is positioned upwardly and displaced with a respective position of the second cooling channel  42  arranged on the second side  122  of the second plate  12 . The reason is that each of cooling channels  41 ,  42  may use, in a horizontal direction (e.g., a y direction), more space than half of the distance between the first and second plates  11 ,  12 . In a vertical direction (e.g., an x direction), the exterior surfaces of the circumferential walls of the cooling channels  41 ,  42  may come close to each other, but in an embodiment, they may not come into contact with each other. 
     A remaining space between the first and second plates  11 ,  12  is left void (e.g., there may be no further solid structures provided in this space). However, the space between the first and second plates  11 ,  12  may be filled with a gas, for example, such as air. This may help to minimize or reduce the heat exchange between the first plate  11  and the second plate  12 . This will be described in more detail below with reference to  FIG.  9   . 
     The outer sides of the intermediate beam  10  illustrated in  FIG.  1    (e.g., the first side  111  of the first plate  11  and the first side  121  of the second plate  12 ) are each adapted to provide direct mechanical support to a row of stacked battery cells (e.g., see  FIGS.  6  and  7   ). For example, a first outer pair of flanges  6111 ,  6112  protrudes from the first side  111  of first plate  11 , and similarly, a second outer pair of flanges  6211 ,  6212  protrudes from the first side  121  of second plate  12 . The first outer pair of flanges  6111 ,  6112  protruding from the first side  111  of the first plate  11  includes an upper outer flange  6111  arranged adjacent to (e.g., close to) the upper edge of first plate  11 , and a lower outer flange  6112  arranged at the lower edge of first plate  11 . Correspondingly, the second outer pair of flanges  6211 ,  6212  protruding from the first side  121  of second plate  12  includes an upper outer flange  6211  arranged adjacent to (e.g., close to) the upper edge of second plate  12 , and a lower outer flange  6212  arranged at the lower edge of second plate  12 . Each of the outer flanges  6111 ,  6112 ,  6211 ,  6212  extends linearly in a direction perpendicular to or substantially perpendicular to the drawing plane of the figure over the length of the respective plate on which the flange is arranged. Then, a right lateral side of a row of stacked battery cells may be fitted between the first outer pair of flanges  6111 ,  6112 . Likewise, a left lateral side of a row of stacked battery cells may be fitted between the second outer pair of flanges  6211 ,  6212 . The lateral sides of the rows of stacked battery cells that are placed adjacent to the respective first sides  111 ,  121  of the first and second plates  11 ,  12  are held in place by the outer flanges  6111 ,  6112 ,  6211 ,  6212  in a vertical direction (e.g., the x direction) with respect to the orientation depicted in  FIG.  1   . 
     To close the space between the first and second plate  11 ,  12  also in a vertical direction, pairs of inner flanges may also be arranged on plates  11 ,  12 , respectively. In more detail, an upper inner flange  6121  protruding from the upper edge of the second side  112  of the first plate  11  extends to (e.g., reaches to) the upper edge of the second side  122  of the second plate  12 . The upper inner flange  6121  is supported from below by a further upper inner flange  6221  protruding from the second side  122  of the second plate  12  from a position close to the upper edge of second plate  12 . In a similar manner, a lower inner flange  6222  protruding from the lower edge of the second side  122  of the second plates  12  extends to (e.g., reaches to) the lower edge of the second side  112  of the first plate  11 . The lower inner flange  6222  is supported from above by a further lower inner flange  6122  protruding from the second side  112  of the first plate  11  from a position close to the lower edge of first plate  11 . Each of the inner flanges  6121 ,  6122 ,  6221 ,  6222  extends linearly in a direction perpendicular to or substantially perpendicular to the drawing plane of the figure over the length of the respective plate on which the flange is arranged. 
     In an embodiment, the cross-sectional profile of each of the plates  11 ,  12  shown in  FIG.  1   , together with their respective structures arranged thereon (e.g., see above), remains constant over the whole extension of the plates  11 ,  12  in the direction perpendicular to or substantially perpendicular to the drawing plane of the figure. Then, each of the plates  11 ,  12  may be manufactured by extrusion techniques. For example, each of the plates  11 ,  12  may be an aluminum extrusion profile. 
     While the above-described structures that are arranged on the second side  112  of the first plate  11  may, in a horizontal direction, overlap with structures arranged on the second side  122  of the second plate  12 , or even contact (e.g., touch) structures arranged on the second side  122  of the second plate  12  (e.g., as in the case of the upper inner flanges  6121 ,  6221  or the lower inner flanges  6122 ,  6222 ), the structures arranged on the first plate  11  may not be fixedly connected to the structures arranged on the second plates  12 . For example, in some embodiments, the first plate  11  and the second plates  12 , with each of their respective structures, may remain displaceable relative to each other in a direction (e.g., a z direction) perpendicular to or substantially perpendicular to the drawing plane of  FIG.  1   . This will be described in more detail below with reference to  FIG.  2   . 
       FIG.  2    schematically illustrates three perspective views (A), (B), and (C) of a first plate  11  and a second plate  12  to be assembled into an intermediate beam  10 . The Cartesian coordinate system having the axes x, y, z depicted in  FIG.  2    applies to any one of these views (A), (B), and (C). In the three perspective views (A), (B), and (C), the first plate  11  and the second plates  12  are shown in different positions relative to each other. The three views (A), (B), and (C) may also be interpreted as different states of a process of assembling the intermediate beam  10  as shown in the view (C). A cross-sectional cut through the assembled intermediate beam  10  as depicted in view (C) corresponds to the view shown in  FIG.  1   . 
     In each of the tree perspective views (A), (B), and (C), each of the plates  11 ,  12  extends in a direction parallel to or substantially parallel to the x-z-plane of the coordinate system. Both plates  11 ,  12  are elongated in the z-direction. The linear extension along the z-direction of the structures arranged on the plates  11 ,  12  and described above with respect to  FIG.  1    is illustrated at least for the first outer pair of flanges  6111 ,  6112  protruding from the first side  111  of the first plate  11 , the inner flanges  6221 ,  6222  protruding from the second side  122  of the second plate  12 , the through-hole  52  of the second plate  12 , the cooling channel  42  of the second plate  12 , and the tongue  32  of the upper dovetail joint and groove  22  of the lower dovetail joint. 
     The view (A) in  FIG.  2    shows the first plate  11  oriented relative to the second plate  12 , such that the respective second sides  112 ,  122  of the plates  11 ,  12  are orientated to be in parallel or substantially in parallel with each other and to face each other. Highlighted by dashed circles are the (lower) tongue  31  arranged on the second side  112  of the first plate  11  and protruding towards the right, as well as the (upper) tongue  32  arranged on the second side  122  of the second plate  12  and protruding towards the left. At suitable positions (e.g., with respect to the x-z-plane of the coordinate system) on the respective opposite plates  11 ,  12  are arranged the (lower) groove  22  on the second side  122  of the second plate  12 , and the (upper) groove  21  on the second side  112  of the first plate  11 . In a state in which the plates  11 ,  12  are connected (e.g., coupled or attached) to each other so as to form the intermediate beam  10  shown in the view (C) of  FIG.  2   , the upper tongue  32  on the second plate  12  is embraced by the upper groove  21  on the first plate  11 , and thus, establishes a coupling of the two plates  11 ,  12  to each other at the upper halves of the plates  11 ,  12 . The assignment of the upper tongue  32  to the upper groove  21  is indicated by an arrow extending from the dashed circle around the upper tongue  32  and pointing to the upper groove  21 . Likewise, the pair of the lower tongue  31  and the lower groove  22  establishes a coupling of the two plates  11 ,  12  to each other at the lower halves of the plates  11 ,  12 , when the lower tongue  31  is embraced by the lower groove  22  as shown in the view (C) of  FIG.  2   . In the view (A) of  FIG.  2   , the assignment of the lower tongue  31  to the lower groove  22  is indicated by an arrow extending from the dashed circle around the lower tongue  31  and pointing to the lower groove  22 . 
     The dovetail joints employed as the coupling means to connect the first and second plates  11 ,  12  to each other are described in more detail below with reference to  FIG.  3   . As described in more detail below with reference to  FIG.  3   , one feature of the employed dovetail joints is that any displacement of the first and second plates  11 ,  12  relative to each other with respect to the x-y plane of the coordinate system may be inhibited by the dovetail joints, while at the same time, movement of the first and second plates  11 ,  12  relative to each other with respect to the z-axis of the coordinate system may be allowed. Likewise, it may not be possible to establish the coupling means by the dovetail joints by simply pressing the respective tongues into the respective grooves. As a consequence, it may also not be possible to connect the respective second sides  112 ,  122  of the first and second plates  11 ,  12  by simply pressing them against each other in the direction of the x-axis of the coordinate system. Rather, the first and second plates  11 ,  12  may be connected to (e.g., coupled to or attached to) each other by aligning the plates  11 ,  12  along the z-direction, such that, when viewed in the z-direction, the cross-sectional profile of the (upper) tongue  32  is embraced within the cross-sectional profile of the (upper) groove  21 , and similarly, the cross-sectional profile of the (lower) tongue  31  is embraced within the cross-sectional profile of the (lower) groove  22 , as effectively shown in  FIG.  1   . It should be noted that from  FIG.  1   , it may not be determined whether the plates  11 ,  12  are in a coupled state, or if they are in a decoupled state but aligned one after the other in a direction perpendicular to or substantially perpendicular to the drawing plane of  FIG.  1   . Subsequently, the plates  11 ,  12  may be connected to (e.g., coupled to or attached to) one another by moving the plates  11 ,  12  against each other in a direction parallel to or substantially parallel to the z-axis of the coordinate system, thereby, telescoping the (upper) tongue  32  into the (upper) groove  21 , and similarly, the (lower) tongue  31  into the (lower) groove  22 . This is shown in the view (B) of  FIG.  2   , where the arrow D indicates that the second plate  12  is shifted into the z-direction, and the arrow −D indicates that the first plate  11  is shifted against the z-direction. Note that during the whole process of telescoping the plates  11 ,  12  into each other (e.g., see the view (B) of  FIG.  2   ), a view upon the ensemble of the first and second plates  11 ,  12  from a direction along the z-axis of the coordinate system may yield a constant picture, such as the picture shown in  FIG.  1   . 
     After having been completely telescoped into one another, the ensemble of the first and second plates  11 ,  12  is shown in the final state depicted in the view (C) of  FIG.  2    (e.g., the state wherein the first and second plates  11 ,  12  are assembled into the intermediate beam  10 ). 
     In summary with reference to  FIG.  2   , the first plate  11  and the second plate  12 , which may each be realized by simple aluminum extrusion profiles, may be telescoped into each other by using established shapes for accurate (linear-)guiding such as the “dovetail guide” shown in the examples of  FIGS.  1  and  2   . Once the first plate  11  and the second plate  12  are slipped into each other, the resulting beam  10  (e.g., see the view (C) in  FIG.  2   ) may be formed, and when employed in a frame for a battery pack (as described in more detail below), may be implemented as a rigid single-piece profile (e.g., beam). 
     While some examples of the coupling means described above employ the dovetail joints, the present disclosure is not limited to the use of dovetail joints. Any other suitable joint inhibiting movements between the plates that are assembled to form a beam, except for a longitudinal movement of the plates relative to each other, may be employed as the coupling means, as long as it suitably provides for the desired demands of stability. Other examples of joints that may be used as the coupling means according to various embodiments of the present disclosure are described in more detail below with reference to  FIGS.  11 ,  12 , and  13   . 
     An embodiment of a coupling mechanism (e.g., a coupling means), which may be employed to connect the respective second sides  112 ,  122  of the first plate  11  and the second plate  12  to each other, will now be described in more detail with reference to  FIG.  3   .  FIG.  3    illustrates an enlarged view of a cut-out of  FIG.  1   , and a schematic view of a dovetail joint. In particular,  FIG.  3    shows a view (A) that is an enlarged cut-out view of an upper area of the intermediate beam  10  depicted in  FIG.  1   , and focuses on the upper dovetail joint (highlighted by the dashed circle) described above with reference to  FIG.  1   . A general principle of a dovetail joint is shown in a schematic view (B) of  FIG.  3   . 
     A first structure P 1  and a second structure P 2 , which may be in contact (e.g., may be in touch) with each other by respective surfaces S 1 , S 2  (wherein the touch may be reduced, however, to a minimum; see below), includes matching features C, B that are in engagement with each other. In more detail, the first structure P 1  includes a cave C having an opening O, and the second structure P 2  includes a bulge B protruding form-fittingly through the opening O in the cave C of the first structure P 1 . The cave C is formed such that a space within the cave C becomes narrower when viewed from a rear end R of the cave C into a direction pointing to the opening O. In other words, with respect to the orientation of the figure, a diameter dc of the cave C measured in the vertical direction may decrease as the horizontal position of the measurement approaches the opening O arranged opposite to the rear end R with respect to the position of the cave C. The hollow space of the cave C may exhibit a conical shape that tapers in the direction pointing from the rear end R to the opening O (e.g., the inner surface of the cave C has a conical shape). Further, the bulge B arranged on the second structure P 2  exhibits the same conical shape tapering in the direction pointing from the rear end R to the opening O, but in an inverted manner (e.g., the outer surface of the bulge B has a conical shape). At its narrowest site, the bulge B is connected to the second structure P 2 . Accordingly, the bulge B that is accommodated in the cave C may not escape out of the cave C through the opening O, as at certain horizontal positions, the diameter of the bulge (e.g., being equal to or substantially equal to the diameter dc of cave C measured at the same horizontal position) is larger than the diameter do of the opening O. Thus, the first structure P 1  and the second structure P 2  are held in fixed positions relative to each other with respect to the two dimensions spanned by the drawing plane of figure by the engagement of the cave C and the bulge B with each other. Due to the above-described tapered shape resembling a dovetail, the connection generated by the cave C and the bulge B is generally termed a dovetail joint. 
     As applied to an embodiment of the present disclosure, each of the first and second structure P 1 , P 2 , as well as the cave C and the bulge B, are elongate structures extending along the direction perpendicular to or substantially perpendicular to the drawing plane of the figure, such that the cross-sectional profile of the ensemble of the structures (as shown in the view (B) of  FIG.  3   ) remains constant for the cross-sectional profiles on any intersecting plane parallel to the drawing plane, as long as the intersecting plane intersects with the ensemble of these structures. As a consequence of this geometry, the first structure P 1  and the second structure P 2  may be moved relative to each other (e.g., the first and second structure P 1 , P 2  are slidable or shiftable with respect to each other) in a direction perpendicular to or substantially perpendicular to the drawing plane of the figure, while at the same time—as described above—the first structure P 1  and the second structure P 2  remain in fixed positions relative to each other with respect to the drawing plane. This effect is exploited in the example of a coupling mechanism used in the intermediate beam  10  depicted in  FIG.  1    as shown in more detail in the view (A) of  FIG.  3   . Despite some minor structural variations in comparison to the connection illustrated in the view (B) of  FIG.  3   , the coupling mechanism shown in the view (A) of  FIG.  3    (e.g., in the area highlighted by the dashed circle) may be a dovetail joint like that shown in the view (B) of  FIG.  3   . 
     In more detail, as shown in the cross-sectional cut view of (a part of) the intermediate beam  10  as depicted in the view (A) of  FIG.  3   , a ground part  21   a  and two walls  21   b ,  21   c  are formed, so as to build a groove  21  extending along the direction perpendicular to or substantially perpendicular to the drawing plane. In the figure, the ground part  21   a  extends in the vertical direction, whereas each of the two walls  21   b ,  21   c  extend in the horizontal direction. The groove  21  corresponds to the cave C in the view (B) of  FIG.  3   , and the opening is formed between the right edges of the two walls  21   b ,  21   c . A conical part of the cave realized by groove  21  is built by end parts  21   b ′,  21   c ′ of the two walls  21   b ,  21   c , in that the end parts  21   b ′,  21   c ′ each have an inclined surface (e.g., that is inclined with respect to each other and also inclined to the horizontal direction of the view (A) of  FIG.  3   ), such that in the area of the end parts  21   b ′,  21   c ′, the hollow space in the groove  21  tapers in a direction pointing from the ground part  21   a  (corresponding to the rear end R in the view (B)) to the opening between the edges of the two walls  21   b ,  21   c . As described above with reference to  FIG.  1   , the groove  21  is fixated on the second side  112  of the first plate  11  of the intermediate beam  10  in an indirect manner (e.g., the groove  21  is formed on the right side of the circumferential wall of through-hole  51 , and is additionally supported by a reinforcing strut  71 , the circumferential wall of the through-hole  51  as well as the reinforcing strut  71  being directly fixated on the second side  112  of the first plate  11 ). 
     Further, a V-shaped tongue  32  extending linearly along the direction perpendicular to or substantially perpendicular to the drawing plane is arranged on the second side  122  of the second plate  12  of the intermediate beam  10 , the tongue  32  being formed by a first inclined part  32   a  and a second inclined part  32   b . The tongue  32  protrudes, from the second side  122  of the second plate  12 , into the groove  21 . In more detail, the first inclined part  32   a  and the second inclined part  32   b  are inclined with respect to each other (e.g., so as to form a lying letter V with the tip thereof pointing to the right in the view (A)), and are also each inclined relative to the horizontal direction of the view (A). With the tip of the letter V formed by the inclined parts  32   a ,  32   b , each of the inclined parts  32   a ,  32   b  are fixedly connected to the second side  122  of the second plate  12 . The inclination of the first inclined part  32   a  corresponds to the inclination of the inner surface of the end part  21   b ′ of upper wall  21   b  of groove  21 , and similarly, the inclination of the second inclined part  32   b  corresponds to the inclination of the inner surface of the end part  21   c ′ of lower wall  21   c  of groove  21 . It should be noted that, in the area close to the ground part  21   a  of the groove  21 , the inclination of the surfaces of the inclined parts  32   a ,  32   b  may deviate, which is, however, not important for the functioning of the described coupling mechanism. As a consequence of the corresponding inclinations of end parts  21   b ′,  21   c ′ of the walls  21   b ,  21   c  of the groove  21  and the surfaces of the inclined parts  32   a ,  32   b  abutting against the end parts  21   b ′,  21   c ′, a similar effect of engaging may be caused as described with reference to the view (B) of  FIG.  3    with respect to the cave C and the bulge B, although, due to the void space between the two inclined parts  32   a ,  32   b , the tongue  32  may not exhibit the compact shape (unlike the compact shape of the bulge B of the view (B) shown in FIG.  3 ). In more detail, the first plate  11  and the second plate  12  may be moved relative to each other (e.g., the first and second plates  11 ,  12  are slidable or shiftable with respect to each other) in a direction perpendicular to or substantially perpendicular to the drawing plane of the figure, while at the same time, the first plate  11  and the second plate  12  are held in fixed positions relative to each other with respect to the drawing plane by the dovetail joint realized by the groove  21  and the tongue  32 . 
     In the following, in order to avoid an unduly restriction of the disclosure to the use of dovetail joints as the coupling mechanisms (e.g., the coupling means), the generic expression “guide rail” will be used to denote both parts of a coupling arranged on the first plate  11  (e.g., the groove  21 ) as well as parts of that coupling arranged on the second plate  12  (e.g., the tongue  32 ). In this context, the expression “guide rail” is to be construed in a broader sense (e.g., such that it is not restricted to a single linearly extending member with a rectangular cross-section, but may also include composed structures like the groove  21  or the tongue  32 ). 
     Depending on application needs required in specific situations, different shapes of the beams (e.g., the profiles) may be used. For example, the outer beams of the battery pack (e.g., a leftmost beam  10   a  and a rightmost beam  10   z  in  FIG.  8   ) may have one side adapted to provide mechanical support to a row of stacked battery cells and an opposite side adapted to terminate the battery pack, thereby, possibly providing additional structures, such as sealing flanges, for an interface to a top and bottom cover of the battery pack. These beams are referred to as “end beams” in the following. Other beams, however, may be suitably shaped, such that they provide mechanical support to two adjacent rows of stacked battery cells positioned at opposite sides of the respective beam. These beams are referred to as “intermediate beams” throughout this disclosure. One example of the intermediate beam has been described above with reference to  FIGS.  1  to  3   . 
     Furthermore, for the sake of brevity, hereinafter, a plate having one side configured to provide mechanical support to a row of stacked battery cells shall be referred to as a “cell supporting plate,” and a plate not having a side configured to provide mechanical support to a row of stacked battery cells shall be referred to as an “end plate.” 
     Different kinds of beams may be simply assembled by using different types of first and second plates, and each type of the first plate is combinable with (e.g., may be coupled to or attached to) each type of the second plate. Examples of different kinds of plates will be described in more detail below with reference to  FIG.  4   . 
     Hereinafter, for convenience, various views shown in the figures will be designated with the figure number followed by the view designation. For example, a view (A) shown in  FIG.  4    may be designated as  FIG.  4 A , and likewise, a view (B) shown in  FIG.  5    may be designated as  FIG.  5 B . 
       FIG.  4    schematically illustrates different kinds of plates to be used in the frame according to one or more embodiments of the present disclosure.  FIG.  5    schematically illustrates different kinds of beams using combinations of the plates shown in  FIG.  4   . 
     On the left side of  FIG.  4   , two different types of first plates are illustrated, whereas on the right side of  FIG.  4   , two different types of second plates are illustrated. In more detail, a type of a first plate  11 B depicted in  FIG.  4 B  corresponds to the first plate  11  shown in  FIGS.  1  to  3    above, and a type of a second plate  12 A depicted in  FIG.  4 C  corresponds to the second plate  12  shown in  FIGS.  1  to  3    above. As described above with reference to  FIG.  1   , the first plate  11  as well as the second plate  12  may include the side adapted to provide mechanical support to a row of stacked battery cells. Accordingly, the type of the first plate  11 B depicted in  FIG.  4 B  as well as the type of the second plate  12 A depicted in  FIG.  4 C  may constitute cell supporting plates. 
     A type of the first plate  11 A illustrated in  FIG.  4 A , however, may constitute an end plate. In more detail, the first plate  11 A is realized as a double plate (e.g., the first plate  11 A includes two parallel sub-plates  11 A 1  and  11 A 2 , and a void space  11   vs  between the two parallel sub-plates  11 A 1  and  11 A 2 ). By varying a thickness of the void space  11   vs , the overall thickness of first plate  11 A may be adapted according to desired geometrical dimensions of the battery pack, when first plate  11 A is used as part of a frame of the battery pack (e.g., see the first beam  10   a  in the battery pack of  FIG.  8   ). Also, the void space  11   vs  provides additional thermal insulation between the exterior of the battery pack and the inside of the battery pack where battery cells  88  are arranged (e.g., see  FIG.  6   ). 
     The sub-plates  11 A 1  and  11 A 2  are held in position by two closing members  61 ,  62 , which also confine the void space  11   vs  in the vertical direction with respect to the orientation of first plate  11 A in  FIG.  4 A . The upper closing members  61  extends, in a horizontal direction, into flanges  61   a ,  61   b  protruding at the upper edge of plate  11 A to the left and to the right. Unlike the left upper flange  6111  of the first plate  11  depicted in  FIGS.  1  to  3  and  4 B , the left upper flange  61   a  of the first plate  11 A is directly arranged at the top edge of first plate  11 A. However, the right upper flange  61   b  of first plate  11 A exhibits a shape corresponding to that of the right upper flange  6121  of first plate  11 . The left upper flange  61   a  and left lower flange  62   a  may be used as an interface for mounting the end plate  11 A to a top cover (and a bottom cover, respectively, of the battery pack. Further, each of the structures provided on the right surface of the right sub-plate  11 A 1  (e.g., the right upper flange, through-hole  51 , upper groove  21 , reinforcing strut  71 , cooling channel  41 , lower tongue  31 , and the right lower flange  6122 ) correspond to respective structures provided on the surface of the second side  112  of first plate  11  as described above with reference to  FIG.  1   . Accordingly, the type of first plate  11 B illustrated in  FIG.  4 A  may be readily connected (e.g., coupled or attached) to the second plate  12 A depicted in  FIG.  4 C , which is the same or substantially the same as the second plate  12  illustrated in  FIGS.  1  to  3    (e.g., see  FIG.  5 C ). 
     Similarly, a type of the second plate  12 B illustrated in  FIG.  4 D  constitutes an end plate. The flanges  64 ,  65  protruding from the first side (e.g., the right side) of the second plate  12 B are positioned and formed in a similar manner as those of the flanges  61   a ,  62   a  protruding to the left side from first plate  11 A depicted in  FIG.  4 A , except for their orientation to the right. On the other hand, the structures arranged on the second side (e.g., the left side) the second plate  12 B each correspond to respective structures arranged on the second side of second plate  12  as described above with reference to  FIG.  1   , with the only difference being that the cooling channel  42  may be omitted in the case of the type of the second plate  12 B illustrated in  FIG.  4 D . In other words, because the second plate  12 B is an end plate, unlike the second plate  12  shown in  FIGS.  1  to  3  and  4 C , there may be no battery cells next to the right side of second plate  12 B when in use. The type of second plate  12 B illustrated in  FIG.  4 D  may be readily connected (e.g., coupled or attached) to the first plate  11 B depicted in  FIG.  4 B , which is the same or substantially the same as the first plate  11  illustrated in  FIGS.  1  to  3    (e.g., see  FIG.  5 G ). However, it should be noted that the type of the second plate  12 B illustrated in  FIG.  4 D  may also be connected (e.g., coupled or attached) to the type of first plate  11 A illustrated in  FIG.  4 A , although this combination may be rarely used as a combination of two end plates (e.g., see  FIG.  5 F ). 
     A compilation of the different possible combinations of connecting (e.g., coupling or attaching) each of the two types of first plates  11 A,  11 B illustrated in  FIGS.  4 A and  4 B , to different ones of the two types of second plates  12 A,  12 B illustrated in  FIGS.  4 C and  4 D  is shown in  FIG.  5   . Each of four resulting combinations thereof may yield a specific type of beam. The first column and the last column shown in  FIG.  5    illustrate the two types of first plates and the two types of second plates, respectively, which are depicted in the left column and the right column of  FIG.  4   , respectively. In more detail,  FIG.  5 A  shows the first end plate  11 A of  FIG.  4 A ,  FIG.  5 E  shows the first cell supporting plate  11 B of  FIG.  4 B ,  FIG.  5 D  shows the second cell supporting plate  12 A of  FIG.  4 C , and  FIG.  5 H  shows the second end plate  12 B of  FIG.  4 D . 
     Further, the different beams assembled by the four possible combinations of the above-described types of plates are shown in the second and third columns of  FIG.  5   . In more detail,  FIG.  5 B  illustrates the first cell supporting plate  11 B (e.g., see  FIGS.  4 B / 5 E) being connected (e.g., coupled or attached) to the second cell supporting plate  12 A (e.g., see  FIGS.  4 C / 5 D). The beam resulting from the combination shown in  FIG.  5 B  corresponds to the intermediate beam  10  described above with reference to  FIGS.  1  to  3   . Further,  FIG.  5 C  illustrates the first end plate  11 A (e.g., see  FIGS.  4 A / 5 A) being connected (e.g., coupled or attached) to the second cell supporting plate  12 A (e.g., see  FIGS.  4 C / 5 D). The combination shown in  FIG.  5 C  results in a first end beam  10   a  illustrated in  FIGS.  6  to  8    as the beam terminating battery pack on the left side (e.g., see below). 
       FIG.  5 F  illustrates the first end plate  11 A (e.g., see  FIGS.  4 A / 5 A) being connected (e.g., coupled or attached) to the second end plate  12 B (e.g., see  FIGS.  4 D / 5 H). The combination shown in  FIG.  5 F  may be rare, and may not be normally used in a frame for supporting rows of stacked battery cells, as this is a combination of two end plates, and thus, none of the lateral sides of the beam shown in  FIG.  5 F  may be configured to provide support (e.g., structural support or technical support) to a row of stacked battery cells. However, the type of beam shown in  FIG.  5 F  may be used in other situations, such as providing additional support to the frame as a whole when being mounted (e.g., in a housing or the like).  FIG.  5 G  illustrates the first cell supporting plate  11 B (e.g., see  FIGS.  4 B / 5 E) being connected (e.g., coupled or attached) to the second end plate  12 B (e.g., see  FIGS.  4 D / 5 H). The combination shown in  FIG.  5 G  results in the second end beam  10   z  illustrated in  FIGS.  6  to  8    as the beam terminating battery pack on the right side (e.g., see below). 
       FIG.  6    schematically illustrates a perspective view of a battery pack  100  according to an embodiment of the present disclosure. 
     Referring to  FIG.  6   , three rows of stacked battery cells  80   a ,  80   b ,  80   c  are mounted into the frame using the beams described above with reference to  FIGS.  1    to  5 . Each of the beams is orientated along the direction of the z-axis of the coordinate system depicted in the figure. Here, each row of stacked battery cells includes two battery cell stacks arranged in parallel with each other and adjacent to each other with respect to the y-axis. For example, the first row of stacked battery cells  80   a  (e.g., the leftmost row of stacked battery cells in  FIG.  6   ) includes a first battery cell stack  80   a   1  and a second battery cell stack  80   a   2 , each being orientated along the z-axis. In an isolated state (e.g., when not mounted in a frame), the first and second battery cell stacks  80   a   1 ,  80   a   2  may be held together by a holding means  89 , which may also provide further means of the row of stacked battery cells  80   a , for example, such as electric terminals. The second row of stacked battery cells  80   b  and the third row of stacked battery cells  80   c  are assembled in the same or substantially the same (e.g., in a similar) manner. 
     In more detail, the first row of stacked battery cells  80   a  is mounted between a first end beam  10   a  that corresponds to the end beam shown in  FIG.  5 C , and a first intermediate beam  10   b  that corresponds to the intermediate beam shown in  FIGS.  2 C and  5 B . As described above, the first end beam  10   a  is assembled by connecting (e.g., coupling or attaching) the first end plate  11 A of  FIG.  5 A  with the second cell supporting plate  12 A of  FIG.  5 D , and the first intermediate beam  10   b  is assembled by connecting (e.g., coupling or attaching) a first cell supporting plate  11 B of the type shown in  FIG.  5 E  with the second cell supporting plate  12 A of the type shown in  FIG.  5 D . Further, the second row of stacked battery cells  80   b  is mounted between the first intermediate beam  10   b  and a second intermediate beam  10   c , which has an assembly that is the same or substantially the same as that of the first intermediate  10   b . The third row of stacked battery cells  80   c  is mounted between the second intermediate beam  10   c  and a second end beam  10   z  that corresponds to the end beam shown in  FIG.  5 G . As described above with reference to  FIG.  5   , the second end beam  10   z  is assembled by connecting (e.g., coupling or attaching) the first cell supporting plate  11 B of  FIG.  5 E  with the second end plate  12 B of  FIG.  5 H . 
     Visible at the front side of the depicted battery pack  100  is both of the lateral sides (e.g., the left and right sides in the figure) of each row of stacked battery cells  80   a ,  80   b ,  80   c , along the direction of the x-axis of the coordinate system, between embracing flanges protruding towards the respective row of stacked battery cells from the cell supporting plates abutting the respective row of stacked battery cells. The flanges have been described above with reference to  FIGS.  1  and  5   . Additionally, the lateral sides of each row of stacked battery cells  80   a ,  80   b ,  80   c  may each be glued to the respective abutting plate. At the rear side of the battery pack  100  illustrated in  FIG.  6   , each of the beams  10   a ,  10   b ,  10   c ,  10   z  are mounted, with their respective rear ends (or distal ends), to the rear bar  94  extending parallel to or substantially parallel to the y-axis of the coordinate system, and thus, perpendicular to or substantially perpendicular to each of the beams  10   a ,  10   b ,  10   c ,  10   z . Also, a front bar may be mounted in a similar manner to each of the respective front end (or proximal ends) of the beams  10   a ,  10   b ,  10   c ,  10   z  (e.g., see  FIG.  8   ). In the embodiment of  FIG.  6   , the frame is built by first and second end beams  10   a ,  10   z , the two intermediate beams  10   b ,  10   c , the rear bar  94 , and possibly also the front bar (not shown). 
     As described above with reference to  FIGS.  1  to  5   , each of the beams  10   a ,  10   b ,  10   c ,  10   z  is assembled from a pair of plates that are connected (e.g., coupled or attached) together, such that any displacement of the respective plates relative to each other in a direction perpendicular to the z-axis is inhibited. Thus, each of the rows of stacked battery cells  80   a ,  80   b ,  80   c  is held, by the frame, in a fixed position relative to the direction of the x-axis (e.g., the vertical direction) as well as in a fixed position relative to the direction of the y-axis (e.g., the horizontal direction). However, in each beam, the respective first and second plates thereof may be connected (e.g., may be coupled or attached) to each other, such that they may be movable relative to each other in a direction parallel to or substantially parallel to the z-axis of the coordinate system. Accordingly, at least one of the plates of the respective beam may not be held in a fixed position with respect to the z-direction by means of the rear bar  94  or the front bar. In other words, if desired, a plate may be configured to be moved such as to be detached from the rear bar  94  and/or the front bar. Also, at least one of the rear bar  94  and, if applicable, the front bar may be demounted from the battery pack  100  to give way for the movement of the plates in a direction parallel to or substantially parallel to the z-axis. Thus, for the following, any possible mounting of beams  10   a ,  10   b ,  10   c ,  10   z  to a rear bar and/or the front bar is neglected. 
     Due to the above-described moveability of the two plates of a beam relative to each other, each of the rows of stacked battery cells  80   a ,  80   b ,  80   c  may be pulled out of the battery pack  100 . This is schematically illustrated in  FIG.  7   .  FIG.  7    illustrates that the second row of stacked battery cells  80   b  has been pulled to the front with respect to the remaining parts of the battery pack  100 . In other words, starting from the position illustrated in  FIG.  6   , the second plate  12   b  of the first intermediate beam  10   b  may be shifted against the z-direction of the coordinate system relative to the first plate  11   b  of first intermediate beam  10   b . Likewise, the first plate  11   c  of the second intermediate beam  10   c  may be shifted against the z-direction relative to the second plate  12   c  of second intermediate beam  10   c.    
     In other words, the second row of stacked battery cells  80   b  together with the second plate  12   b  of first intermediate beam  10   b  and the first plate  11   c  the second intermediate beam  10   c  may form (e.g., may be regarded as) a drawer or tray, which may be pulled out of the battery pack  100  in a direction indicated by the arrow A, and/or, if the “tray” is already pulled out as illustrated in  FIG.  7   , may be pushed back into the battery pack  100  against the direction indicated by the arrow A. It should be appreciated, however, that the tray including the second row of stacked battery cells  80   b  may also be removed from the battery pack  100 , and may be replaced by a further tray assembled in the same or substantially the same manner to have the same or substantially the same geometry as that of the tray with the row of stacked battery cells  80   b . Accordingly, the battery pack  100  may be easily repaired, for example, in the case of a defective second row of stacked battery cells  80   b  or the like. 
       FIG.  7    schematically illustrates a split beam of the battery pack shown in  FIG.  6   . In  FIG.  7   , a tray including the second row of stacked battery cells  80   b  together with the second plate  12   b  of the first intermediate beam  10   b  and the first plate  11   c  the second intermediate beam  10   c  is shown as being pulled out of the battery pack  100 . It should be understood, however, that each of the other trays (e.g., the tray including the first row of stacked battery cells  80   a  together with respective first and second plates of the respective adjacent beams  10   a ,  10   b , and the tray including the third row of stacked battery cells  80   c  together with respective first and second plates of the respective adjacent beams  10   z ,  10   c ) may also be pulled out of the battery pack  100  or pushed into the battery pack  100  in the same or substantially the same manner as that shown in  FIG.  7   . Accordingly, the replacement of the first row of stacked battery cells  80   a  or the third row of stacked battery cells  80   c  may also be easily performed with the frame and the battery pack  100  depicted in  FIG.  7   . 
       FIG.  8    schematically illustrates a battery pack according to another embodiment of the present disclosure. The battery pack  100 A shown in  FIG.  8    includes six rows of stacked battery cells  80   a ,  80   b ,  80   w ,  80   x ,  80   y ,  80   z  orientated in parallel to or substantially in parallel to each other in the direction of the z-axis the coordinate system. Similar to the embodiment shown in  FIG.  6   , each of the six rows of stacked battery cells  80   a ,  80   b ,  80   w ,  80   x ,  80   y ,  80   z  is mounted between two beams (e.g., one beam attached to the left lateral side of the respective row of stacked battery cells, and a further beam attached to the right lateral side of the respective row of stacked battery cells). In more detail, the first row of stacked battery cells  80   a  (e.g., counted from the left to the right of the figure) is mounted between the first end beam  10   a  and the first intermediate beam  10   b  in the same or substantially the same fashion as that of the first row of stacked battery cells  80   a  of the embodiment of the battery pack  100  described above with reference to  FIG.  6   . Similarly, the sixth row of stacked battery cells  80   z  is mounted between the fifth intermediate beam  10   f  and the second end beam  10   z  in the same or substantially the same fashion as that of the third row of stacked battery cells  80   c  of the embodiment of the battery pack  100  described above with reference to  FIG.  6   . Further, each of the second, third, fourth, and fifth row of stacked battery cells  80   b ,  80   w ,  80   x ,  80   y  is mounted between two intermediate beams that are attached to the respective lateral sides of the respective row of stacked battery cells. 
     Each of the beams  10   a ,  10   b ,  10   c ,  10   d ,  10   e ,  10   f ,  10   z  is orientated along the direction of the z-axis of the coordinate system. The rear ends (e.g., the distal ends) of the beams are each mounted to a rear bar  94  orientated perpendicular to or substantially perpendicular to the beams along the direction of the y-axis. Likewise, the front ends (e.g., the proximal ends) of the beams are each mounted to a front bar  92  orientated parallel to or substantially parallel to the rear bar  94 . Accordingly, the whole ensemble of beams, bars, and rows of stacked battery cells extends on a plane parallel to or substantially parallel to the y-z-plane of the coordinate system. Each of the front and rear bars  92 ,  94  may include a series of through-holes  90 , through which screws or bolts may be guided so as to penetrate into respective through-holes arranged in the plates of the beams, for example, as illustrated in  FIG.  1   . For example, the front bar  92  may be mounted to the front end (e.g., the proximal end) of the first intermediate beam  10   b  by a screw or bolt guided through the through-hole  90  visible on the front side of front bar  92 , the screw or bolt then penetrating into the upper through-hole  51  arranged on the second side  112  of the first plate  11  of the first intermediate beam  10   b , which corresponds to the intermediate beam  10  shown in  FIG.  1   . 
     With the above description concerning the beams as each being assembled using a pair of coupled plates (e.g., see the description as to  FIGS.  1  to  5   ) and the description as to  FIG.  7   , it follows that each of the rows of stacked battery cells  80   a ,  80   b ,  80   w ,  80   x ,  80   y ,  80   z  together with the plates of the beams to which the respective row of stacked battery cells is attached, forms of a drawer or tray which may be pulled out of the battery stack  100 A or pushed into the battery stack  100 A, when the plates connected to the respective row of stacked battery cells are not fixated to the front bar  92  and/or the rear bar  94 , and at least one of the front bar  92  and the rear bar  94  is demounted from the battery pack  100 A. 
     A grip or handle  98  may also be mounted onto the battery pack in order to facilitate pulling out the battery pack from a housing where the battery pack may be accommodated, or to put it back again into the housing. Also, further means used for the battery pack, such as electric terminals and the like, may be arranged on the grip or handle  98 . In the battery pack  100 A depicted in  FIG.  8   , the grip or handle  98  is mounted to the left ends of the front and rear bar  92 ,  94 . 
       FIG.  9    schematically illustrates heat insulation provided by a beam of the frame according to one or more embodiments of the present disclosure. 
       FIG.  9    schematically illustrates the heat propagation between two neighboring rows of stacked battery cells  80   i ,  80   i+1  through an intermediate beam  10   i+1  of the frame according to one or more embodiments of the present disclosure. In the example shown in  FIG.  9   , the intermediate beam  10   i+1  corresponds to the intermediate beam  10  shown in  FIGS.  1  and  2   , and may be any one of the intermediate beams  10   b ,  10   c  used in the battery pack  100  of  FIGS.  6  and  7   , or any one of the intermediate beams  10   b ,  10   c ,  10   d ,  10   e ,  10   f  used in the embodiment of the battery pack  100 A shown in  FIG.  8   . 
     The safety of the battery pack depends on its ability to avoid or at least to decelerate the heat propagation from a row of stacked battery cells affected by an abnormal thermal event (e.g., such as a thermal run-away) to neighboring rows of stacked battery cells in order to avoid or at least to decelerate a spread of the thermal event within the battery pack. Thus, it may be desirable for the beams, such as the intermediate beams, to provide a high degree of heat insulation. Good heat insulation is provided by vacuum or gases, such as air. As illustrated in  FIG.  9   , a space S (e.g., most of the space S) between the first plate  11   i+1  and the second plate  12   i+1  of the intermediate beam  10   i+1  may be left void, and thus, filled with air. The cooling channels (e.g., the circumferential walls thereof)  41   i+1 ,  42   i+1  arranged on the first plate  11   i+1  and the second plate  12   i+1 , respectively, do not come into mechanical contact with each other. Indeed, the contact points (e.g., the only contact points) between the first plate  11   i+1  and the second plate  12   i+1  are established by the flanges and the dovetail joints. In more detail, a mechanical contact area L 1  is established between the upper inner flanges  6121   i+1 ,  6221   i+1  protruding from the second sides of first plate  11   i+1  and the second plate  12   i+1 , respectively. Similarly, a further mechanical contact area L 6  is established between the lower inner flanges  6122   i+1 ,  6222   i+1  protruding from the second sides of first plate  11   i+1  and the second plate  12   i+1 , respectively. Also, there are mechanical contact areas L 2 , L 3  between the groove  21   i+1  and the tongue  32   i+1  of the upper dovetail joint, and further contact areas L 4 , L 5  between the groove  22   i+1  and the tongue  31   i+1  of the lower dovetail joint of intermediate beam  10   i+1 . 
     Accordingly, in case of the thermal event T, such as a thermal run-away occurring (e.g., at the left row of stacked battery cells  80   i  abutting to the first plate  11   i+1 , and thus, immediately heating the first plate  11   i+1  as indicated by the arrows H), the heat propagation to the second plate  12   i+1  and then further to the right side of stacked battery cells  80   i+1  is largely inhibited by the void space between the two plates  11   i+1 ,  12   i+1 . The heat exchange between the plates is essentially restricted to the above-identified six contact areas L 1 , L 2 , L 3 , L 4 , L 5 , L 6 , where the two plates  11   i+1 ,  12   i+1  are in direct mechanical contact with each other. This is indicated by the small arrows being based in the contact areas L 1 , L 2 , L 3 , L 4 , L 5 , L 6 , which also indicate the respective direction of the heat propagation. However, as can be seen from the figure, the total area built by the areas L 1 , L 2 , L 3 , L 4 , L 5 , L 6  is small in comparison to the total area of the second sides of each of the plates  11   i+1 ,  12   i+1 . Thus, the intermediate beam  10   i+1  may provide an extremely high degree of heat insulation. Hence, due to a structure of the intermediate beam  10   i+1  in the battery pack as described above with reference to  FIGS.  6  to  8   , an expansion or propagation of a thermal event from one affected row of stacked battery cells to other rows of stacked battery cells may be inhibited or reduced. 
     Accordingly, as shown in  FIG.  9   , in the case of thermal events, such as a thermal run-away within one row of stacked battery cells, the split beams (e.g., profiles) may reduce or minimize the heat impact to neighboring rows of stacked battery cells, because there may be minor contact surfaces within the beams (e.g., between the plates, which the beams are assembled from), as shown by the contact areas L 1 , L 2 , L 3 , L 4 , L 5 , L 6  and indicated by the respective arrows in these contact areas. 
       FIG.  10    schematically illustrates adhesive layers used to glue battery cells to a beam of the frame according to one or more embodiments of the present disclosure. 
       FIG.  10    schematically illustrates a fixation of rows of stacked battery cells (e.g., all or at least a part of the battery cells included in each of these rows of stacked battery cells) to an intermediate beam  10   i+1  corresponding to the intermediate beam  10  shown in  FIGS.  1  and  2   . In the example shown in  FIG.  10   , a first layer of adhesive  81  is used to glue the left row of stacked battery cells  80   i , with its right lateral side, to the first side (e.g., the left side) of the first plate  11   i+1 . Similarly, a second layer of adhesive  82  is used to glue the right row of stacked battery cells  80   i+1 , with its left lateral side, to the first side (e.g., the right side) of second plate  12   i+1 . Thus, in addition to the mechanical support to the rows of stacked battery cells provided by the flanges of a beam protruding from the respective first sides of the plates (e.g., as described above with reference to  FIG.  1   ), in some embodiments, chemical means may be further used for the fixation of the rows of stacked battery cells to the beam. 
     Even when the rows of stacked battery cells are fixated as shown in  FIG.  10   , it may be possible to draw the rows of stacked battery cells out of the battery pack as illustrated in  FIG.  7   . For example, it may not be necessary to remove the adhesive layers between a certain row of stacked battery cells and the two beams to which it is fixated, because the plates to which the row of stacked battery cells is fixated are pulled out of the battery pack together with the row of stacked battery cells by exploiting the assembly of the beams as described above, and thus, two plates may be telescoped into one another (e.g., as shown in  FIGS.  2 B and  7   ) albeit the rows of stacked battery cells being fixated thereto. 
     Therefore, even if a failure occurs within a row of stacked battery cells or within a battery cell module, it may be possible to easily exchange the defective unit, even if the rows of stacked battery cells and/or the individual battery cells  88  are joined to the respective adjacent beams with structural adhesives, such as the adhesive layers  81 ,  82  shown in  FIG.  10   . 
       FIG.  11    schematically shows an example of a coupling means according to an embodiment of the present disclosure.  FIG.  12    schematically shows an example of a coupling means according to another embodiment of the present disclosure.  FIG.  13    schematically shows an example of a coupling means according to another embodiment of the present disclosure. 
     As described above with reference to  FIG.  3   , there are various embodiments of the coupling means that allow for a linearly slidable connection between two members (e.g., such as the plates) along or against one direction (e.g., the z direction), but that also inhibit any displacement of the two members relative two each other in or against other directions. 
     A few such examples of the coupling means are schematically illustrated in  FIGS.  11 ,  12 , and  13   , which may be used instead of, or in addition to, the dovetail joints described above with reference to  FIG.  3   . In more detail, a simple joint may be used as shown in  FIGS.  11 A through  11 C . The illustrated joint in  FIGS.  11 A through  11 C  allows for the connecting (e.g., the coupling or attaching) of a first member  201  and a second member  202  to each other. The first member  201  may include a first linear edge  210  being formed to be thickened and having a bulge shape. The second member  202  may include a second linear edge  220  having a tube-like structure with a slit therethrough. Through the slit, the first member  201  extends into an interior of the second linear edge  220 , such that the first linear edge  210  is accommodated in the interior of the second linear edge  220 . In other words, the first linear edge  210  of the first member  201  and the second linear edge  220  of the second member  202  are in engagement with each other so as to form a connection (e.g., a coupling or an attachment) between the first member  201  and the second member  202 . Due to the linear expansion of the first linear edge  210  as well as that of the second linear edge  220  along the z-direction, the connection (e.g., the coupling or the attachment) allows for linearly shifting the first member  201  relative to the second member  202  in or against the z-direction. 
     In more detail, to use the simple joint illustrated in  FIG.  11 A , the first member  201  may be connected to the first plate of a beam as described above, and the second member  202  may be connected to the second plate of the beam. For example, the upper dovetail joint (e.g., formed by the upper groove  21  and the upper tongue  32 ) of the intermediate beam  10  illustrated in  FIGS.  1  and  3 A  may be replaced by the joint shown in  FIG.  11 A . However, depending on a width of the slit, rotation of the first member  201  relative to the second member  202  around the z-axis may be possible to a certain degree. In order to avoid an undesired rotational degree of freedom between the first plate and the second plate of the beam, two of the joints may be used to connect the first plate with the second plate. For example, in the intermediate beam  10  illustrated in  FIGS.  1  and  3 A , both the upper dovetail joint (e.g., the upper groove  21  and the upper tongue  32 ) and the lower dovetail joint (e.g., the lower groove  22  and the lower tongue  31 ) may each be replaced by a joint of the type shown in  FIG.  11 A . 
     Irrespective of the type of coupling means used to connect (e.g., couple or attach) the first plate and second plate to each other in a beam, in some embodiments, at least two connections/joints arranged with a suitable distance to each other may be provided to increase the rotational stability of the established connection (e.g., coupling or attachment) of the plates (e.g., to avoid or reduce rotations of the plates relative to each other). 
     To facilitate the establishment of the connection with the joint as illustrated in  FIG.  11 A , a part of the first linear edge  210  may include a skewed plane  210   a  (e.g., a plane  210   a  that is inclined), in which the first member  201  extends. This is schematically illustrated in  FIG.  11 B . Then, the diameter of the first linear edge  210  is reduced in a direction perpendicular to or substantially perpendicular to the skewed plane  210   a  when compared to the diameter of the first linear edge  210  in a direction perpendicular to or substantially perpendicular to the plane, in which the first member  201  extends. Accordingly, the first linear edge  210  may be pushed into the second linear edge  220  through the slit of the second linear edge  220 , when the first linear edge  210  is led through the slit in a direction X parallel to or substantially parallel to the skewed plane  210   a  (the direction X not being parallel to the z-direction as shown in  FIG.  11 A ). When the second member  202  is subsequently rotated relative to the first member  201  around the z-direction (e.g., in a clockwise rotational direction from the perspective of  FIG.  11 B ), the connection (e.g., the coupling or attachment) between the first member  201  and the second member  202  is established, as illustrated schematically in  FIG.  11 C . 
     Another type of connection that may be used to realize the coupling means according to embodiments of the present disclosure is a clip joint as schematically illustrated in  FIG.  12   . In  FIG.  12   , a first member  310  is connected to a second member  320 . The first member  310  may be connected to a first plate of the beam as described above with reference to  FIGS.  1  and  3 A , and the second member  320  may be connected to the second plate of the beam. Each of the first member  310  and the second member  320  extends linearly along the z-direction. The first member  310  includes a pair of inclined surfaces (e.g., a first inclined surface  311   a  and a second inclined surface  311   b ) extending toward each other in a direction towards the second member  320 . A first elevation  312   a  is arranged on the first inclined surface  311   a , and correspondingly, as second elevation  312   b  is arranged on the second inclined surface  311   b . Each of the elevations  312   a ,  312   b  extends linearly along the z-direction. 
     The second member  320  includes a pair of parallel planes (e.g., a first plane  321   a  and a second plane  321   b ). A first hook  322   a  is arranged at an edge of the first plane  321   a  on a side facing the second plane  321   b , and correspondingly, a second hook  322   b  is arranged at an edge of the second plane  321   b  on the side facing the first plane  321   a . Each of the hooks  322   a ,  322   b  extends linearly along the respective edge of the respective plane  321   a ,  321   b  in the z-direction. The pair of inclined surfaces  311   a ,  311   b  of the first member  310  is configured to be shifted into the space between the planes  321   a ,  321   b , such that the first inclined surface  311   a  comes into contact with the first plane  321   a , and correspondingly, the second inclined surface  311   b  comes into contact with the second plane  321   b , as illustrated in  FIG.  12   . In this state, the first hook  322   a  arranged on the first plane  321   a  engages with the first elevation  312   a  arranged on the first inclined surface  311   a , and correspondingly, the second hook  322   b  arranged on the second plane  321   b  engages with the second elevation  312   b  arranged on the second inclined surface  311   b . In other words, the pair of inclined surfaces  311   a ,  311   b  and the pair of hooks  322   a ,  322   b  establish a clip joint. Due to the above-described construction of the clip joint, the first member  310  may be slid or shifted in or against the z-direction relative to the second member  320 , while any other displacement as well as rotations of the first member  310  and the second member  320  relative to each other are impeded by the illustrated clip joint. 
     Another type of connection that may be used to realize the coupling means according to embodiments of the present disclosure is the joint schematically illustrated in  FIG.  13   , which may be a further type of clip joint. In  FIG.  13   , a first member  410  is connected to a second member  420 . The first member  410  may be connected to a first plate of the beam as described above with reference to  FIGS.  1  and  3 A , and the second member  420  may be correspondingly connected to the second plate of the beam. Each of the first member  410  and the second member  420  extends linearly along the z-direction, and exhibits a planar shape (e.g., an essentially planar shape). The first member  410  includes a first protrusion  412  protruding perpendicularly or substantially perpendicularly (e.g., essentially perpendicularly) from the first member  410 . At the tip of the first protrusion  412 , a first hook  412   a  is arranged. Both, the first protrusion  412  and the first hook  412   a  extend linearly along the z-direction. At an edge of first member  410 , a nose  411  is arranged, which likewise extends linearly along the z-direction. The nose  411  protrudes slightly inclined with respect to the plane of first member  410  on the side of the first member  410  on which the first protrusion  412  is also arranged. The profile of nose  411  may be curved. 
     The second member  420  includes an edge  421   a  being thickened in comparison to a thickness of the plane of the second member  420  at positions other than the edge  421   a . A clip member  422  protrudes from one side of the second member  420 . The clip member  422  extends linearly along the z-direction. The cross-sectional profile of the clip member  422  that is perpendicular to or substantially perpendicular to the z-direction is buckled and protrudes over the thickened edge  421   a  of the second member  420 . In more detail, the clip member  422  includes a first buckle  422   a  and a second buckle  422   b . Accordingly, the clip member  422  includes a first portion  422 - 1  between the plane of the second member  420  and the first buckle  422   a  of the clip member  422 , a second portion  422 - 2  between the first buckle  422   a  and the second buckle  422   b , and a third portion  422 - 3  after the second buckle  422   b . From the second portion of clip member  422 , a second protrusion  421   c  is arranged that protrudes toward the extension of the plane, in which the second member  420  extends. Each of the buckles  422   a ,  422   b  and each of the portions  422 - 1 ,  422 - 2 ,  422 - 3  of the clip member  422  extends linearly along the z-direction. Due to this arrangement, a cave is formed between the thickened edge  421   a  of the second member  420 , the first portion  422 - 1  of the clip member  422 , and the second protrusion  421   c . In more detail, the cave is shaped such that the nose  411  of the first member  410  may be accommodated in the cave. After the second buckle  422   b , the clip member  422  bends into the third portion  422 - 3 , which is arranged such as to protrude towards the extension of the plane, in which second member  420  extends. At the tip of the third portion  422 - 3 , a second hook  422   c  is arranged. 
     To connect the first member  410  with the second member  420 , the nose  411  of first member  410  is led into the cave formed by the thickened edge  421   a  of second member  420 , the first portion  422 - 1  of clip member  422 , and the second protrusion  421   c  as described above. In this state, the first member  410  and the second member  420  are rotatable (up to some degree) with respect to each other around an axis directed along the z-direction through the interior of the cave. To fix the connection, the first member  410  may be rotated with respect to the second member  420 , such that the first protrusion  412  of the first member  10  overlaps, within an area, with the third portion  422 - 3  of the clip member  422  of the second member  420 , such that the first hook  412   a  engages with the second hook  422   c . Once the first hook  412   a  is engaged with the second hook  422   c , any rotational movement as well as any translational displacement of the first member  410  relative to the second member  420  is prevented or substantially prevented, except for a translational shift of the first member  410  and the second member  420  relative to each other in or against the z-direction. 
     Although some embodiments have been described, those skilled in the art will readily appreciate that various modifications are possible in the embodiments without departing from the spirit and scope of the present disclosure. It will be understood that descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments, unless otherwise described. Thus, as would be apparent to one of ordinary skill in the art, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific embodiments disclosed herein, and that various modifications to the disclosed embodiments, as well as other example embodiments, are intended to be included within the spirit and scope of the present disclosure as defined in the appended claims, and their equivalents. 
     REFERENCE SIGNS 
     
         
           10 ,  10   i+1  intermediate beam 
           10   a  first end beam 
           10   b, c, d, e, f  intermediate beams 
           10   z  second end beam 
           11 ,  11 A,  11 B,  11   b ,  11   c ,  11   i+1  first plate 
           11 A 1 ,  11 A 2  sub-plates 
           11   vs  void space 
           12 ,  12 A,  12 B,  12   b ,  12   c ,  12   i+1  second plate 
           21 ,  22  grooves 
           21   i+1 ,  22   i+1  grooves 
           21   a  ground part 
           21   b ,  21   c  walls 
           21   b ′,  21   c ′ end parts 
           31 ,  32  tongues 
           31   i+1 ,  32   i+1  tongues 
           32   a ,  32   b  inclined parts of a tongue 
           41 ,  41   i+1 ,  42 ,  42   i+1  cooling channels 
           51 ,  52  through-holes 
           61 ,  62  closing members 
           61   a ,  61   b ,  62   a ,  64 ,  65  flanges 
           71 ,  72  reinforcing strut 
           80   a ,  80   b ,  80   c ,  80   w ,  80   x ,  80   y ,  80   z  rows of stacked battery cells 
           80   i ,  80   i+1  rows of stacked battery cells 
           80   a   1 ,  80   a   2  battery cell stacks 
           81 ,  82  adhesive layers 
           88  battery cell 
           89  holding means 
           90  through-hole in front bar 
           92 ,  94  front and rear bar 
           98  grip or handle 
           100 ,  100 A battery pack 
           111 ,  112  first side and second side of first plate 
           121 ,  122  first side and second side of second plate 
           121 B,  122 B first side and second side of second end plate 
           201 , first member 
           202  second member 
           210  first linear edge 
           210   a  skewed plane 
           220  second linear edge 
           310  first member 
           311   a ,  311   b  inclined surfaces 
           312   a ,  312   b  elevations 
           320  second member 
           321   a ,  321   b  planes 
           322   a ,  322   b  hooks 
           410  first member 
           411  nose 
           412  first protrusion 
           412   a  first hook 
           420  second member 
           421   a  thickened edge 
           421   c  second protrusion 
           422  clip member 
           422 - 1 ,  422 - 2 ,  422 - 3  portions 
           422   a ,  422   b  buckles 
           422   c  second hook 
           6111 ,  6112 ,  6121 ,  6122  flanges on first plate 
           6121   i+1 ,  6122   i+1  flanges on first plate 
           6211 ,  6212 ,  6221 ,  6222  flanges on second plate 
           6221   i+1 ,  6222   i+1  flanges on second plate 
         A arrow 
         B bulge 
         C cave 
         D, −D arrows 
         dc, do diameters 
         H arrow indicating heat propagation 
         L 1 , L 2 , L 3 , L 4 , L 5 , L 6  contact areas of heat exchange 
         O opening 
         P 1 , P 2  structures 
         R rear end of cave 
         S space 
         S 1 , S 2  surfaces 
         T thermal runaway 
         x, y, z axes of a Cartesian coordinate system 
         X direction