Battery pack for an electrical device

Abstract

comprising battery pack (1) for an electrical device - an outer casing (2) and at least two battery cells (4a, 4b) arranged inside the outer casing (2) and each having a cell shell; - an electrical connecting element (6, 6a, 6b, 6c) which electrically connects a first electrode region (5a, 5b) on the cell shell of a first battery cell (4a, 4b) of the at least two battery cells (4a, 4b) to a second electrode region (5a, 5b) on the cell shell of a second battery cell (4a, 4b) of the at least two battery cells (4a, 4b); and - has a heat dissipation element (7) which thermally connects the connecting element (6, 6a, 6b, 6c) to an inner wall of the outer casing (2).

Description

[0001] The present invention relates to a battery pack for an electrical device comprising an outer casing and at least two battery cells arranged inside the outer casing, each having a cell shell, as well as an electrical connecting element which electrically connects a first electrode region on the cell shell of a first battery cell of the at least two battery cells to a second electrode region on the cell shell of a second battery cell of the at least two battery cells. The invention further relates to a system comprising such a battery pack and an electrical device.

[0002] Battery-powered electrical devices, such as power tools, are often designed to be supplied with electrical energy by battery packs known as system battery packs or interchangeable battery packs. With such interchangeable battery packs, the outer casing of the battery pack can be mechanically and electrically attached to the housing of the electrical device and, if necessary, for example for charging, storage, or use with a different electrical device, easily removed, for instance by releasing a corresponding locking mechanism or similar.

[0003] The electrodes of the battery cells in such a battery pack are electrically interconnected, for example in series, parallel, or according to a more complex interconnection topology. This interconnection can be achieved using appropriate electrical connecting elements, such as linker plates.

[0004] As the current-carrying capacity of individual battery cells increases, for example through the use of so-called tableless designs, thermal management within the battery pack becomes increasingly important.

[0005] It is an object of the present invention to achieve improved heat dissipation of heat generated by the battery cells in a battery pack for an electrical device.

[0006] This problem is solved by the subject matter of the independent claim. Advantageous further developments and preferred embodiments are the subject matter of the dependent claims.

[0007] The invention is based on the idea of ​​providing a heat dissipation element in the battery pack, which thermally connects an electrical connecting element, which connects two battery cells of the battery pack to each other, with an inner wall of the outer casing of the battery pack.

[0008] According to one aspect of the invention, a battery pack for an electrical device, in particular a power tool, is provided. The electrical device has an outer housing and at least two battery cells arranged inside the outer housing, each having a cell casing. The electrical device has an electrical connecting element that electrically connects a first electrode area on the cell casing of a first battery cell of the at least two battery cells to a second electrode area on the cell casing of a second battery cell of the at least two battery cells. The electrical device has a heat dissipation element that thermally connects the connecting element to an inner wall of the outer housing.

[0009] The battery pack can be designed in particular as a replaceable battery pack, also known as a system battery pack.

[0010] The battery pack, in particular its outer casing, can be detachably, and especially non-destructively, connected to the housing of the electrical device, for example via a snap-fit ​​connection, a plug connection, and / or a clamp connection. In particular, the mechanical connection between the outer casing of the battery pack and the housing of the electrical device can be designed as a positive-locking and / or force-locking connection without a material bond. In other words, the mechanical connection between the outer casing of the battery pack and the housing of the electrical device can be released without breaking a material bond. Preferably, the mechanical connection can be released manually as intended, without the use of any other tools.

[0011] For electrical and mechanical connection, the housings of the battery pack and the electrical device can each have corresponding interfaces. In particular, the outer casing of the battery pack can be mechanically and electrically connected to the housing of the electrical device without the use of a cable between the battery pack and the housing of the electrical device. For example, the outer casing of the battery pack is immovable relative to the housing of the electrical device when the outer casing of the battery pack is attached to the housing of the electrical device, and this connection is not released by a corresponding mechanism.

[0012] An electrical connection between the at least two battery cells and the electrical device, in particular a motor or other electrical component of the device, can be established, for example, via one or more detachable electrical contacts, such as clamp contacts or plug contacts, in particular so-called tulip contacts or sword contacts. For example, compatible plugs or sockets, or receptacles or the like, can be provided at the interfaces of the corresponding housings to achieve the electrical connection of the battery pack to the electrical device.

[0013] In some embodiments, the battery pack can provide an output voltage in the range of 12V to 60V. In some embodiments, the battery pack can have a capacity of 2 Ah to 15 Ah.

[0014] Each of the at least two battery cells has an anode and a cathode, which correspond, for example, to respective areas of the cell shell that are electrically insulated from each other.

[0015] In some embodiments, the cell casing can be solid, for example made of metal or partially made of metal, especially if the at least two battery cells are cylindrical battery cells.

[0016] In cylindrical battery cells, the electrode surfaces are typically located on the base or top surface of the respective cylinder. The first electrode area of ​​the first battery cell thus corresponds to the anode or cathode of the first battery cell, and the second electrode area of ​​the second battery cell corresponds to an anode or cathode of the second battery cell. The specific combination depends in particular on the concrete wiring topology. The arrangement of the connecting element and the heat dissipation element according to the invention can be implemented independently of this.

[0017] The connecting element establishes an electrical connection between the first electrode surface and the second electrode surface. This can be, for example, one or more metal sheets, so-called linker sheets, or other electrical connectors.

[0018] During operation, the electrical connector may be located in an area of ​​the battery pack where significant heat generation occurs. By incorporating a heat dissipation element that thermally connects the connector to the inner wall of the outer casing, the locally generated heat can be more effectively dissipated, particularly to the outer casing of the battery pack. The heat dissipation effect can be further enhanced by appropriately selecting the shape and / or materials of the outer casing or the inner wall component.

[0019] Furthermore, the mechanical connection of the connecting element via the heat dissipation element to the inner wall of the outer casing results in increased mechanical stability. This can lead to improved robustness of the battery pack, particularly in the event of impacts or vibrations. Specifically, it can reduce the risk of damage to the connecting element or to an electrical connection between the connecting element and the battery cells due to external influences such as impacts or vibrations. The heat dissipation element can therefore advantageously contribute to both improved thermal management and improved mechanical stability of the battery pack.

[0020] According to at least one embodiment, the heat dissipation element comprises a metal sheet or consists of the metal sheet. One surface of the metal sheet is in thermal contact with the connecting element, and another surface of the metal sheet opposite this surface is in thermal contact with the inner wall of the outer housing.

[0021] For example, the surface of the metal sheet can be in direct contact with the fastener. This includes joining materials such as adhesives, especially thermally conductive adhesives, or metallic materials for soldering or welding the metal sheet to the fastener, and so on. This also applies analogously to the thermal contact of the rest of the metal sheet's surface with the inner wall of the outer housing.

[0022] In particular, the surface of the metal sheet can be welded to the connecting element and / or the surface of the metal sheet can be bonded to the connecting element, especially by means of a thermally conductive adhesive. In some embodiments, the connection between the further surface of the metal sheet and the inner wall of the outer housing can be force-fit and / or form-fit, whereby a material-fit connection is not necessarily required. However, it is also possible that the further surface of the metal sheet is alternatively or additionally material-fitted to the inner wall of the outer housing, for example by appropriate bonding or the like.

[0023] In designs incorporating the metal sheet, particularly good heat dissipation can be achieved with low weight and low cost of the heat dissipation element. Furthermore, the connection between the connecting element and the heat dissipation element can be established particularly easily. In addition, the metal sheet has the advantage that it can be precisely adapted to the spatial conditions inside the outer casing of the battery pack through forming processes.

[0024] According to at least one embodiment, the metal sheet is bent so that it forms at least three sub-areas. A first sub-area of ​​the at least three sub-areas extends in a plane or substantially in the plane. The term "substantially" can be understood here and in the following, in particular, to include typical or unavoidable tolerances, especially manufacturing and / or assembly tolerances, and / or material variations.

[0025] A second sub-area of ​​at least three sub-areas also extends in the plane or substantially in the plane. A third sub-area of ​​at least three sub-areas extends in a further plane or substantially in a further plane. This further plane is distinct from the plane and, in particular, parallel to the plane, and the third sub-area is located between the first and second sub-areas. For example, the third sub-area borders both the first and the second sub-areas. In other words, the third sub-area is located between the first and the second sub-areas.

[0026] In a viewing direction perpendicular to the plane and the next plane, the third sub-area thus forms a kind of projection over the first sub-area and the second sub-area, which is achieved through the aforementioned offset.

[0027] This design of the metal sheet allows for a simple and space-saving arrangement of the heat dissipation element, whereby the different components to be connected by the heat dissipation element—namely, the inner wall of the outer housing on the one hand and the connecting element on the other—can be in contact with the corresponding sections of the metal sheet. The offset also allows for bridging any spatial gap between the inner wall of the outer housing and the connecting element. Furthermore, this design can create a simpler friction-fit connection with the inner wall of the outer housing, either as an alternative or in addition to a material-fit and / or form-fit connection, by appropriately pre-tensioning the metal sheet.

[0028] In some embodiments, for example, the third sub-area is in thermal contact, for example in direct contact, with the connecting element, and the first sub-area is in thermal contact, in particular in direct contact, with the inner wall of the outer housing, and / or the second sub-area is in thermal contact, for example direct contact, with the inner wall of the outer housing.

[0029] This method allows for particularly good thermal contact between the inner wall of the outer casing and the heat dissipation element. This can be further improved if both the first and second sections are in thermal contact with the inner wall of the outer casing. In particular, this can improve the force-fit connection.

[0030] In other embodiments, the first sub-area or the second sub-area is in thermal contact, in particular direct contact, with the connecting element, in particular either the first sub-area or the second sub-area. The third sub-area is in thermal contact, in particular direct contact, with the inner wall of the outer housing.

[0031] This allows for more efficient use of the available installation space. If the first section is in thermal contact with the connecting element, the second section of the metal sheet can, for example, be in thermal contact with another connecting element or other component of the battery pack, where heat is potentially generated, which can also be dissipated to the inner wall of the outer casing via the same heat dissipation element.

[0032] According to at least one embodiment, the outer casing comprises a thermally conductive plastic component that forms the inner wall of the outer casing. This thermally conductive plastic component has, in particular, an inner surface that forms the inner wall of the outer casing and an outer surface that faces the external environment of the battery pack. In this way, the heat transferred from the connecting element to the outer casing or the thermally conductive plastic component via the heat dissipation element can be efficiently dissipated to the environment of the battery pack.

[0033] The thermally conductive plastic can, for example, be a plastic with embedded thermally conductive particles, such as boron nitride or similar materials. In particular, the thermally conductive plastic can also be electrically insulating, which is especially advantageous for the present application.

[0034] According to at least one embodiment, the first battery cell and the second battery cell are cylindrical cells. The first electrode region is located on an end face of the cell casing of the first battery cell, and the second electrode region is located on an end face of the cell casing of the second battery cell.

[0035] The end face can in particular be a base or top surface of the cylindrical basic shape, i.e. a side that does not correspond to a lateral surface of the cylindrical basic shape.

[0036] The cell membrane can consist of a solid material or of several parts of a solid material. The solid material can be, for example, a metal.

[0037] Particularly with cylindrical battery cells, very high current-carrying capacities can be achieved, for example, by implementing so-called tabless designs for internal contacting of the active layers with the inside of the cell shell. In such embodiments, heat generation at the connecting element is particularly critical, making the invention especially advantageous in this respect.

[0038] According to at least one embodiment, the connecting element includes or consists of a connecting plate. The connecting plate is, in particular, another metal plate. The connecting plate can also be referred to, for example, as a link plate.

[0039] In this way, the contacting of the connecting element with the first and second electrode areas can be easily achieved, for example by welding, and the thermal connection between the connecting element and the heat dissipation element can also be easily established, especially if the heat dissipation element includes or consists of the metal sheet. For example, the metal sheet can be welded or soldered to the at least one connecting plate.

[0040] According to at least one embodiment, the connecting plate consists of a copper-iron alloy, for example a CuFe2 alloy.

[0041] It has been shown that this results in a good electrical connection between the battery cells with improved heat dissipation through the connecting element itself.

[0042] In some embodiments, the metal sheet of the heat dissipation element is also made of the copper-iron alloy.

[0043] According to at least one embodiment, the connecting element, in particular the connecting plate, is welded to the cell shell of the first battery cell, in particular in the first electrode area, and to the cell shell of the second battery cell, in particular in the second electrode area.

[0044] For example, the welding of the connecting plate to the cell shell of the first battery cell may include first welding points, for example three or more first welding points, and / or the welding of the connecting plate to the cell shell of the second battery cell may include second welding points, for example three or more second welding points.

[0045] By using three or more welding points, good electrical contact can be achieved on the one hand, and a spatial distribution of the generated heat in the area of ​​the respective electrode surface can be achieved on the other hand, thus reducing the risk of damage to active materials inside the respective battery cell.

[0046] According to at least one embodiment, the first welding points are each at least 1 mm apart from a center point of the end face of the cell casing of the first battery cell.

[0047] In other words, the center of the front face of the cell shell of the first battery cell is free of weld points of the first weld points.

[0048] Leaving the center of the cell's end face exposed can be advantageous for several reasons. In particular, with cylindrical cells, such as those in a tableless design, the central area of ​​the end faces is especially critical with regard to thermal overload. By placing the welding points outside the center, damage during welding, i.e., during the manufacturing process of the battery pack, can be avoided. Furthermore, battery cells, especially cylindrical cells, often have a current interrupt device (CID), which is also attached to the end face of the cell. Damage to such CIDs during welding can also be avoided by placing them outside the center.

[0049] According to at least one embodiment, the second welding points are each at least 1 mm apart from a center point of the end face of the cell casing of the second battery cell.

[0050] In other words, the center of the front face of the cell casing of the second battery cell is free of weld points of the second weld points.

[0051] According to at least one embodiment, the end face of the cell shell of the first battery cell has an edge, in particular an outer contour, in the form of a first circle, and the first welding points are each at least ten percent of the diameter of the first circle away from the center of the first circle.

[0052] This method also ensures that the center of the front face remains free of weld points. The advantages mentioned above therefore also apply to such embodiments.

[0053] According to at least one embodiment, the end face of the cell shell of the second battery cell has an edge, in particular an outer contour, in the form of a second circle, and the second welding points are each at least ten percent of the diameter of the second circle away from the center of the second circle.

[0054] According to at least one embodiment, the three or more first weld points are arranged such that they form vertices of an N-gon, wherein the number of three or more first weld points is equal to N. The N-gon is a regular N-gon or a mirror-symmetric N-gon with an axis of symmetry passing through two of the three or more first weld points.

[0055] The corresponding highly symmetrical arrangement of the welding points allows for a particularly large distance between the welding points, which reduces the maximum heat development when welding the connecting plate to the cell shell and also leads to an improved distribution of the generated heat.

[0056] According to at least one embodiment, the three or more second weld points are arranged such that they form vertices of an M-gon, wherein the number of three or more second weld points is equal to M. The M-gon is a regular M-gon or a mirror-symmetric M-gon with an axis of symmetry passing through two of the three or more second weld points.

[0057] According to at least one embodiment, the first battery cell and the second battery cell are designed according to a tableless design.

[0058] This increases the maximum current-carrying capacity of the first and second battery cells, making the invention particularly advantageous.

[0059] According to at least one embodiment, the battery pack is designed as a replaceable battery pack.

[0060] According to another aspect of the invention, a system is specified which includes a battery pack according to the invention and an electrical device which can be operated by means of the battery pack.

[0061] In particular, the electrical device includes an electric motor or other electrical consumer that can be powered by the battery pack.

[0062] Further features of the invention are evident from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as those mentioned below in the description of the figures and / or illustrated in the figures, may be encompassed by the invention not only in the combinations specified, but also in other combinations. In particular, embodiments and combinations of features that do not include all the features of an originally formulated claim may also be encompassed by the invention. Furthermore, embodiments and combinations of features that go beyond or deviate from the combinations of features mentioned in the claims may also include the invention.

[0063] The invention is explained in more detail below with reference to specific exemplary embodiments and corresponding schematic drawings. Identical or functionally equivalent elements in the drawings may be provided with the same reference numerals. The description of identical or functionally equivalent elements is not necessarily repeated with respect to the different figures.

[0064] The figures show: Fig. 1 a schematic representation of an exemplary embodiment of a battery pack according to the invention for an electrical device; Fig. 2 a schematic representation of components of a further exemplary embodiment of a battery pack according to the invention; Fig. 3 a schematic representation of components of another exemplary embodiment of a battery pack according to the invention; Fig. 4 a schematic representation of components of another exemplary embodiment of a battery pack according to the invention; Fig. 5 a schematic representation of components of another exemplary embodiment of a battery pack according to the invention; Fig. 6 a schematic representation of components of a further exemplary embodiment of a battery pack according to the invention; and Fig. 7 a schematic representation of components of another exemplary embodiment of a battery pack according to the invention.

[0065] In Fig. Figure 1 schematically illustrates an exemplary embodiment of a battery pack 1 according to the invention for an electrical device, in particular a power tool. The battery pack 1 is specifically designed as a replaceable battery pack.

[0066] The battery pack 1 comprises an outer casing 2 and at least two battery cells 4a, 4b, which are arranged inside the outer casing 2 and each has a cell shell. The battery pack 1 has an electrical connecting element 6, for example, a metal sheet, which electrically connects a first electrode area 5a on the cell shell of a first battery cell 4a of the at least two battery cells 4a, 4b to a second electrode area 5b on the cell shell of a second battery cell 4b of the at least two battery cells 4a, 4b. Furthermore, the battery pack 1 has a heat dissipation element, for example, also a metal sheet, which thermally connects the connecting element to an inner wall of the outer casing 2.

[0067] For example, the outer housing 2 includes a component 3, which forms the inner wall of the outer housing 2. The component 3 can, for example, form a side wall of the outer housing 2 or a part of the side wall. The component 3 can, for example, be made of or have a thermally conductive plastic.

[0068] In the Fig. In Figure 1, component 3 is shown such that it extends in an xy-plane, whereas a z-direction is perpendicular to the xy-plane and therefore correspondingly perpendicular to component 3 and the inner wall of the outer casing 2. This orientation is maintained in the remaining figures unless otherwise stated.

[0069] In Fig. Figure 2 shows a side view of the heat dissipation element 7 of another exemplary embodiment of a battery pack according to the invention, which is designed, for example, as a metal sheet.

[0070] In this embodiment, the metal sheet of the heat dissipation element 7 is cranked, resulting in three sub-areas 7a, 7b, 7c, with the third sub-area 7c being arranged between the first sub-area 7a and the second sub-area 7b.

[0071] In the illustrated example, the connecting element 6a is connected to the heat dissipation element 7 in the second sub-area 7b on a surface of the metal sheet of the heat dissipation element 7, for example, by bonding it with a thermally conductive adhesive 8. On another surface of the metal sheet of the heat dissipation element 7 opposite the surface of the metal sheet, the heat dissipation element 7 is in contact with component 3, i.e., the inner wall of the outer housing 2.

[0072] Another embodiment is shown in Fig. 3 shown. The example of the Fig. 3 largely corresponds to the Fig. 2, however, the connecting element 6b is attached here in the first sub-area 7a to the surface of the metal sheet of the heat dissipation element 7, in particular by means of the thermally conductive adhesive 8.

[0073] The connecting element 6b has separate, adjacent finger-shaped elements. One, more, or all of these finger-shaped elements can, for example, be connected to different electrode surfaces of different battery cells 4a, 4b, or the like. A combination of the embodiments of Fig. 2 and Fig. 3 is in Fig. 4 shown.

[0074] Another alternative embodiment is in Fig. 5 shown. Here's how it's shown in the Fig. 2 and Fig. 3, only a connecting element 6c is shown, which, as in the example of the Fig. 3, designed with finger-shaped elements. In the exemplary embodiment of the Fig. 5, however, the connecting element 6c is connected to the surface of the metal sheet of the heat dissipation element 7 in the third sub-area 7c and optionally also in the first and / or second sub-area 7a, 7b, for example by means of the thermally conductive adhesive 8.

[0075] Another exemplary embodiment is shown in Fig. Figure 6 shows the top view on the left and the corresponding side view on the right.

[0076] The metal sheet of the heat dissipation element 7 and the metal sheet of the connecting element 6 are, as can be seen particularly in the side view on the right, welded together, for example. In the top view on the left, it can be seen that this welding was carried out in the area of ​​two overlapping tongue elements 10a, 10b of the connecting element 6 and the heat dissipation element 7, respectively. The connecting element 6 is welded to the first electrode area 5a of the first battery cell 4a at a plurality of weld points 9a and to the second electrode area 5b of the second battery cell 4b at a plurality of weld points 9b. In the exemplary embodiment of the Fig. Figure 6 also shows weld points 9c and 9d on the heat dissipation element 7. These can be welded to corresponding electrode surfaces of other battery cells of the battery pack 1. In other words, in such embodiments, the heat dissipation element 7 simultaneously serves as an electrical connection element for other battery cells.

[0077] It is also possible that in some embodiments the plurality of weld points 9c of the heat dissipation element 7 are connected to the first electrode surface of the first battery cell and the plurality of weld points 9d of the heat dissipation element 7 are connected to the second electrode surface 5b of the second battery cell 4b. The heat dissipation element 7 thus additionally serves here as a further electrical connecting element for the electrical connection of the first and / or second battery cell 4a, 4b.

[0078] Another geometric embodiment of the connecting element 6 and the heat dissipation element 7 is shown schematically in Fig. 7 is shown. The heat dissipation element 7 is designed, for example, as shown with respect to Fig. 6 described. The connecting element 6 can in particular be designed in a double-T shape, wherein the heat dissipation element 7 is arranged over a T of the double-T shape of the connecting element 6. REFERENCE MARK LIST: 1 battery pack 2 outer casings 3 components 4a, 4b battery cells 5a, 5b Electrode areas 6, 6a, 6b, 6c Connecting elements 7 Heat dissipation element 7a, 7b, 7c Sub-areas 8 Adhesive 9a, 9b, 9c, 9d Welding points 10a, 10b Tongue elements

Claims

[1] Battery pack (1) for an electrical appliance - an outer casing (2) and at least two battery cells (4a, 4b) arranged inside the outer casing (2) and each having a cell shell; - an electrical connecting element (6, 6a, 6b, 6c) which electrically connects a first electrode region (5a, 5b) on the cell shell of a first battery cell (4a, 4b) of the at least two battery cells (4a, 4b) to a second electrode region (5a, 5b) on the cell shell of a second battery cell (4a, 4b) of the at least two battery cells (4a, 4b); and - has a heat dissipation element (7) which thermally connects the connecting element (6, 6a, 6b, 6c) to an inner wall of the outer casing (2). [2] Battery pack (1) according to claim 1, wherein the heat dissipation element (7) comprises a metal sheet, wherein a surface of the metal sheet is in thermal contact with the connecting element (6, 6a, 6b, 6c) and a further surface of the metal sheet opposite the surface is in thermal contact with the inner wall of the outer housing (2). [3] Battery pack (1) according to claim 2, wherein the surface of the metal sheet is welded to the connecting element (6, 6a, 6b, 6c). [4] Battery pack (1) according to claim 2, wherein the surface of the metal sheet is bonded to the connecting element (6, 6a, 6b, 6c). [5] Battery pack (1) according to one of claims 2 to 4, wherein the metal sheet is bent so that it forms at least three sub-areas (7a, 7b, 7c), wherein - a first sub-area (7a) of the at least three sub-areas (7a, 7b, 7c) extends in a plane or extends substantially in the plane; - a second sub-area (7b) of the at least three sub-areas (7a, 7b, 7c) extends in the plane or extends substantially in the plane; - a third sub-area (7c) of the at least three sub-areas (7a, 7b, 7c) extends to a further level or extends substantially to the further level; - the further plane is parallel to the plane and the third sub-area (7c) is arranged between the first sub-area (7a) and the second sub-area (7b). [6] Battery pack (1) according to claim 5, wherein - the third sub-area (7c) is in thermal contact with the connecting element (6, 6a, 6b, 6c); and - the first sub-area (7a) is in thermal contact with the inner wall of the outer housing (2) and / or the second sub-area (7b) is in thermal contact with the inner wall of the outer housing (2). [7] Battery pack (1) according to claim 5, wherein - the first sub-area (7a) or the second sub-area (7b) is in thermal contact with the connecting element (6, 6a, 6b, 6c); and - the third sub-area (7b) is in thermal contact with the inner wall of the outer casing (2). [8] Battery pack (1) according to one of the preceding claims, wherein the outer casing (2) has a component (3) made of thermally conductive plastic which forms the inner wall of the outer casing (2). [9] Battery pack (1) according to one of the preceding claims, wherein the first battery cell (4a, 4b) and the second battery cell (4a, 4b) are cylindrical cells, wherein the first electrode region (5a, 5b) is located on an end face of the cell shell of the first battery cell (4a, 4b) and the second electrode region (5a, 5b) is located on an end face of the cell shell of the second battery cell (4a, 4b). [10] Battery pack (1) according to claim 9, wherein the end face of the first battery cell (4a, 4b) and the end face of the second battery cell (4a, 4b) are facing the inner wall of the outer casing (2). [11] Battery pack (1) according to one of the preceding claims, wherein the connecting element (6, 6a, 6b, 6c) includes a connecting plate. [12] Battery pack (1) according to claim 11, wherein the connecting plate is made of a copper-iron alloy. [13] Battery pack (1) according to one of claims 11 or 12, wherein the connecting plate is welded to the cell shell of the first battery cell (4a, 4b) and to the cell shell of the second battery cell (4a, 4b). [14] Battery pack (1) according to claim 13, wherein - the welding of the connecting plate to the cell casing of the first battery cell (4a, 4b) includes three or more initial weld points (9a, 9b, 9c, 9d, 14a, 14b, 16); and / or - the welding of the connecting plate to the cell shell of the second battery cell (4a, 4b) includes three or more second welding points (9a, 9b, 9c, 9d, 14a, 14b, 16). [15] Battery pack (1) according to claim 14, wherein - the first three or more weld points (9a, 9b, 9c, 9d, 14a, 14b, 16) are each at least 1 mm apart from a center point on the end face of the cell casing of the first battery cell (4a, 4b); and / or - the three or more second welding points (9a, 9b, 9c, 9d, 14a, 14b, 16) are each at least 1 mm apart from a center point of the end face of the cell shell of the second battery cell (4a, 4b). [16] Battery pack (1) according to claim 14, wherein - the end face of the cell casing of the first battery cell (4a, 4b) has a border in the form of a first circle and the three or more first welding points (9a, 9b, 9c, 9d, 14a, 14b, 16) are each at least 10% of the diameter of the first circle away from the center point of the first circle; and / or - the front face of the cell shell of the second battery cell (4a, 4b) has a border in the form of a second circle and the three or more second welding points (9a, 9b, 9c, 9d, 14a, 14b, 16) are each at least 10% of the diameter of the second circle away from the center of the second circle. [17] Battery pack (1) according to one of claims 14 to 16, wherein - the first three or more weld points (9a, 9b, 9c, 9d, 14a, 14b, 16) are arranged such that they form vertices of an N-gon, wherein the number of the first three or more weld points (9a, 9b, 9c, 9d, 14a, 14b, 16) is N, and wherein the N-gon is a regular N-gon or a mirror-symmetric N-gon with an axis of symmetry passing through two of the first three or more weld points (9a, 9b, 9c, 9d, 14a, 14b, 16); and / or - the three or more second weld points (9a, 9b, 9c, 9d, 14a, 14b, 16) are arranged such that they form vertices of an M-gon, wherein the number of three or more second weld points (9a, 9b, 9c, 9d, 14a, 14b, 16) is equal to M, and wherein the M-gon is a regular M-gon or a mirror-symmetric M-gon with an axis of symmetry passing through two of the three or more second weld points (9a, 9b, 9c, 9d, 14a, 14b, 16). [18] Battery pack (1) according to one of the preceding claims, wherein the first battery cell (4a, 4b) and the second battery cell (4a, 4b) are designed according to a tableless design. [19] Battery pack (1) according to one of the preceding claims, wherein the battery pack (1) is designed as a replaceable battery pack (1). [20] System comprising a battery pack (1) according to one of the preceding claims and an electrical device which can be supplied with electrical energy by means of the battery pack (1).

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