Busbar element, arrangement of cell poles of battery cells interconnected by means of such busbar elements, and method for connecting cell poles

Abstract

A busbar element comprising a base body (20) having a planar contact area (22) for contacting a cell pole (14) of a battery cell (12), comprising a first coupling area comprising a first coupling element (24), and a second coupling area comprising a second coupling element (28), wherein the first coupling element (24) and the second coupling element (28) are designed to be complementary to each other such that the first coupling element (24) can be connected to a second coupling element (28) of a second, identically designed busbar element (18) by frictional and / or positive locking, characterized in that the base body (20) is formed integrally with the first coupling element (24) and the second coupling element (28).

Description

[0001] The invention relates to a busbar element, an arrangement of several busbar elements for interconnecting cell poles of at least two battery cells, in particular battery cells of a motor vehicle energy storage system, and a method for connecting cell poles of at least two battery cells using busbar elements. In particular, the invention relates to motor vehicle energy storage systems with a plurality of battery cells, each with at least one cell pole, wherein the cell poles are at least partially interconnected using several busbar elements. Reference is also made to motor vehicles with busbar elements or arrangements according to the invention.

[0002] The invention relates in particular to busbar elements for battery cells of a motor vehicle energy storage system. Such battery cells can have a dimensionally stable battery cell housing, which is usually prismatic (e.g., cuboid or cylindrical). However, the battery cells can also have an elastically deformable casing, as is the case, for example, with pouch cells. The invention preferably relates to battery cells with a dimensionally stable battery housing, in particular those with two cell poles, which are either both arranged on the same side of the battery housing or on opposite sides of the battery housing.

[0003] A battery cell within the meaning of the invention is understood to be, in particular, a battery cell which is intended to be used in a drive energy storage device (also traction battery) of a vehicle. Such battery cells frequently have a cell voltage of 1.5 V to 10 V and preferably 2.5 V to 4.5 V.

[0004] With regard to prismatic battery cells, particular reference is made to battery cell housings having a length of 100 mm to 300 mm, preferably 180 mm to 280 mm. The width of such a prismatic battery cell is preferably 50 mm to 150 mm, preferably 80 mm to 120 mm. The height of a prismatic battery cell is preferably 10 mm to 50 mm, more preferably 20 mm to 40 mm.

[0005] Regarding the use of the terms length and width in connection with battery cells, length has been defined above as the largest dimension, width as the second largest, and height as the smallest, regardless of how the battery cells are arranged in a battery housing in a motor vehicle. In practice, the height, extending upwards in the vehicle's vertical direction when installed in a motor vehicle, is often the second largest dimension. In this case, the battery cells have a long body with a relatively small width extending horizontally perpendicular to the longitudinal direction and a height, which is greater than the width, extending upwards in the vehicle's vertical direction.

[0006] Battery cells according to the invention preferably have a weight of 1 kg to 10 kg, particularly preferably 1 kg to 5 kg and more preferably 1.5 kg to 2.5 kg.

[0007] The cell poles of the battery cells, to which the invention relates in particular, usually protrude from the respective battery housing as planar elements, e.g. in the form of cylindrical or cuboid projections.

[0008] In practice, several battery cells, as described above, are often connected to form a drive energy storage system or a battery module for a drive energy storage system using cell connectors in the form of large-area plates. This is achieved by connecting the cell terminals to the connection areas provided on the cell connectors. This is frequently done by welding. A disadvantage of known welded cell connectors is that replacing or inspecting a single battery cell is very time-consuming, as all or at least a large number of the welds must be broken and thus destroyed.

[0009] From US 2021 / 0280949 A1, a busbar frame, referred to as a "busbar frame," is known which has a plurality of recesses for arranging electrodes referred to as "electrode leads." The busbar frame has a plurality of elements with a U-shaped cross-section. How the busbar frame is to be manufactured in detail is not disclosed. Nor is any reference made to individual busbar elements within the meaning of the invention.

[0010] From US 2020 / 0020913 A1, a planar connection module with busbar modules is known. Each busbar module consists of a plate, referred to as a "sheet member," to which a plurality of individual busbar elements are attached. The busbar elements are also formed from flat plates, which have coupling elements in the form of through-holes for receiving the cell terminals of a battery cell and coupling elements in the form of through-holes for connecting to the plate. In the illustrated embodiment, the busbar elements are connected to the plate by means of rivets. Length compensation elements, referred to as "extension and contraction portions," are also provided on the plate.

[0011] From EP 3 588 614 A1, a pouch cell and a stack with a plurality of pouch cells are known. The pouch cell comprises a positive contact tab and a negative contact tab, via which the pouch cell can be electrically contacted and thus charged and discharged. The pouch cell is planar and has a flat cell surface that extends parallel to the positive and negative contact tabs. The positive and negative contact tabs each have an upper connecting element and a lower connecting element, arranged on opposite sides of the contact tabs. In the stack, the pouch cells are electrically contacted with each other via their respective connecting elements.

[0012] A double-headed connection device for a battery module of an electric vehicle is known from CN 106328878 A. The device comprises a pair of guide shells and a male and a female connector, each slidably arranged in one of the two guide shells. The male and female connectors each have a detachable connection head and a connection seat. The male connector can be made and detached by sliding it against the female connector. In the contacted state, the male connector is movable transversely to the female connector within a predetermined range, and the connection head is movable longitudinally to the connection seat within a predetermined range. For this purpose, the double-headed connection device comprises a plurality of separate components that are complex to assemble.

[0013] The invention is based on the objective of providing a busbar element, an arrangement of such cell poles of battery cells interconnected by means of busbar elements, and a method for connecting cell poles of at least two battery cells by means of busbar elements, which enable time-efficient assembly and flexible disassembly.

[0014] The problem is solved according to the invention by the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

[0015] A busbar element according to the invention comprises a base body having a planar contact area for contacting a cell terminal of a battery cell. Furthermore, the busbar element according to the invention comprises a first coupling area, which has a first coupling element, and a second coupling area, which has a second coupling element. The first coupling element and the second coupling element are designed to be complementary to each other such that the first coupling element can be connected to a second coupling element of a second, identically designed busbar element by frictional and / or positive locking.In this context, a connection means that a first busbar element can be connected to a second busbar element in at least one direction, such that the two busbar elements are held together by friction or positive locking when an attempt is made to pull them apart against the direction of connection. Therefore, a connection within the meaning of the invention also includes simply hooking elements together if this creates a positive locking connection in one direction such that the interlocked busbar elements are positively connected to each other when an attempt is made to pull them apart against the direction of connection.

[0016] According to the invention, the base body is formed integrally with the first coupling element and the second coupling element. The manufacturing process can, in principle, be carried out in any manner. It is particularly advantageous if the base body is manufactured from a plate-like element and both the first and second coupling elements are formed by shaping the respective ends of the plate-like element.

[0017] The planar contact area of ​​the base body comprises, in particular, a contact surface that is preferably designed to be complementary to the contact surface of a cell pole to which the busbar element is subsequently to be connected. Such a contact surface is, in particular, flat and smooth.

[0018] A busbar element according to the invention is preferably made of a material that has good electrical conductivity and can be connected to a cell terminal of a battery cell by welding. A busbar element according to the invention has the advantage that several such busbar elements can be easily connected to one another, and simple connections to the cell terminals of battery cells can be made from the connected busbar elements by welding. Because the busbar elements can be used with one another in a form-fit and / or force-fit manner, it is possible, for maintenance purposes or to replace a single battery cell, to disconnect the connection of a busbar element to a cell terminal, to release the form-fit and / or force-fit connection of the busbar element to one or more other busbar elements, and then to make the battery cell accessible or to replace it.It is still possible to remove a battery cell together with a busbar element by releasing the form-fit and / or force-fit connection and replace it with a new battery cell with a new busbar element.

[0019] For manufacturing reasons, in a practical embodiment it is preferred if the base body is designed as a single planar element whose thickness is significantly smaller than its length and width, particularly if the thickness corresponds to a maximum of 20% of the smaller dimensions of length and width, preferably a maximum of 10%, and most preferably a maximum of 5%. In this case, the installation space requirement of a busbar element according to the invention is particularly small. Furthermore, the busbar element can in this case be produced simply and cost-effectively as a stamped part, a casting, a forging, or as an element manufactured by a mechanical machining process. These processes include, in particular, machining by milling and machining using a laser beam.

[0020] Notwithstanding the foregoing, it is further preferred if the base body of a busbar element according to the invention is spring-elastic in its longitudinal direction. This has the advantage that length compensation is made possible, particularly when such compensation is required due to heat, mechanical loads, or manufacturing tolerances.

[0021] In another practical embodiment of a busbar element according to the invention, the first coupling element and the second coupling element are arranged or formed at opposite ends of the base body. This has the advantage that subsequent formation of the coupling elements, in particular by forming, can be implemented simply and cost-effectively.

[0022] The formation and manufacture of the coupling elements can be carried out with the same tool if the first and second coupling elements are identical. In this regard, particular reference is made to the possibility of forming both the first and second coupling elements as hook elements with a U-shaped or arc-shaped cross-section. For example, one end of a plate-like element, which is used as the starting material for manufacturing a busbar element according to the invention, can be formed by bending or edging a first end. The second coupling element can then be formed either in a subsequent process step with the same tool or, in parallel with the formation of the first coupling element, with a separate tool in the same manner.It has proven particularly advantageous if one hooking element is formed at one end in a first direction and the second hooking element is formed at an opposite end of the base body in an opposite direction.

[0023] Regardless of whether the first and / or second coupling element is a hook element or a differently designed coupling element, attention is drawn to the possibility of designing the first and / or second coupling element with an arc and / or profile, in particular to achieve a relative alignment of two identically designed busbar elements to each other during connection. For example, two interlocking hook elements with an arc shape can cause the two interacting hook elements to center themselves relative to each other, so that the respective outer edges of the busbar elements are aligned parallel to each other.The same effect can be achieved with appropriately profiled hook elements, for example, hook elements that, instead of an arc-shaped contour, have a triangular contour, an interlocking structure, or a contour suitable for relative alignment with each other, e.g., with a V-shaped projection on one busbar element and a corresponding and cooperating V-shaped recess on another busbar element.

[0024] In another practical embodiment of a busbar element according to the invention, the first coupling element is designed as a plug-in element and the second coupling element is designed as a bushing element adapted to the plug-in element. In this case, particularly flat busbar elements can be produced, which are preferably connected to each other exclusively by frictional engagement.

[0025] In conjunction with busbar elements with a plug-in element and a socket element as described above, it is particularly preferred if the socket element and / or the plug-in element have at least one elastically deformable area. In this regard, particular reference is made to an elastically deformable projection on a plug-in element and to an elastically expandable socket on a socket element. Such a socket can, in particular, be formed by two claw-like wall sections arranged relative to each other, the distance between which can be varied by elastically bending at least one wall section, especially to enable a force-fit connection between the plug-in element and the socket element.

[0026] The invention also relates to an arrangement of at least two busbar elements as described above on at least two battery cells, each of which has a battery cell housing and at least one cell pole projecting from the battery cell housing, wherein the two busbar elements are connected to each other by means of interoperating coupling elements in a force-fit and / or form-fit manner, and each of the busbar elements is connected to a cell pole via its contact surface. In this case as well, the connection between the contact surface and the cell pole is preferably made by welding. Reference is hereby made again to the advantages already described above in connection with the busbar elements.

[0027] In a practical embodiment of an arrangement according to the invention, a plurality of cell terminals of battery cells are interconnected via a plurality of busbar elements, wherein a separate busbar element is arranged on each battery cell and each busbar element is positively and / or frictionally connected to at least one further busbar element. A plurality of cell terminals refers in particular to at least 5 cell terminals, preferably at least 8 cell terminals, and more preferably at least 10 cell terminals, or even at least 15 cell terminals or at least 20 cell terminals, wherein the same number of busbar elements is used for the connection. With 8-10 battery cells, or with 12, 15, 20, or 24 battery cells and the connection of a corresponding number of cell terminals, a battery module for a drive energy storage system of a motor vehicle can be formed.In an arrangement according to the invention, replacing a single battery cell requires only breaking the weld connection between a busbar and a battery cell, and then removing the busbar from the arrangement. Once a new battery cell has been inserted, the missing busbar can be reinserted into the arrangement, and the contact area of ​​the inserted busbar can be reconnected to the battery cell by welding. Alternatively, it is possible to first establish the connection between a busbar and a cell terminal of a battery cell and then integrate the busbar-battery cell unit into a battery system.

[0028] For the sake of completeness, it should also be noted that the connection of two busbar elements according to the invention, for the interchangeability described above from a previously assembled arrangement with several busbar elements, requires that a busbar element arranged centrally between two identically designed busbar elements be detachable from the corresponding connection in a direction transverse to the connection direction. This is particularly relevant in conjunction with the Fig. The embodiments described in 1-4 are possible, which will be discussed in more detail below.

[0029] The invention also relates to a method for connecting the cell terminals of at least two battery cells using at least two busbar elements as described above, in which the two busbar elements are connected to each other by frictional and / or positive locking, and the contact areas of the busbar elements are subsequently connected to the cell terminals. In this respect, particular reference is made to the possibility of connecting the busbar elements to the cell terminals by welding. However, the connection of the busbar elements to the cell terminals can also be effected by other means, such as by material bonding, frictional bonding, and / or positive locking.

[0030] Further practical embodiments of the invention are described below in connection with the drawings. They show: Fig. 1 an arrangement of several busbar elements with hook elements according to a first embodiment of battery cells arranged next to each other at cell poles in a side view, Fig. 2 only two of the busbar elements according to the first embodiment at the cell poles of the adjacently arranged battery cells Fig. 1 in a top view, Fig. 3 a busbar element with hook elements according to a second embodiment in an isometric view and Fig. 4 a busbar element with a plug-in element and a socket element according to a further embodiment in an isometric representation.

[0031] Fig. Figure 1 shows an arrangement of two battery cells 12 arranged side by side. Each battery cell 12 has a battery cell housing 10, with at least one cell terminal 14 protruding from the battery cell housing 10. In the illustrated embodiment, the cell terminal 14 is cylindrical and has a flat, smooth upper surface 16. The upper surface 16 of each cell terminal 14 is connected to a busbar element 18 by means of a weld.

[0032] As can be seen from a synthesis of the Fig. 1 and Fig. As can be seen in Figure 2, the busbar elements 18 have a length IB, a width bB, and a height hB. In the illustrated embodiment, the height hB is significantly less than the length IB and the width bB.

[0033] The busbar elements 18 are formed from a base body 20 which is in contact with a planar contact area 22 on the respective upper surface 16 of the cell pole 14.

[0034] At a first longitudinal end, a hook-in element 26 is formed as the first coupling element 24. At the opposite longitudinal end, a further hook-in element 26 is formed as the second coupling element 28. The hook-in elements 26 have a U-shaped cross-section when viewed in a longitudinal section.

[0035] As from Fig. As can be seen in Figure 1, the busbar elements 18 are positively connected to each other in the connection direction V indicated by the double arrow due to the design of the hook elements 26.

[0036] In the width direction, perpendicular to the connection direction V, the busbar elements 18 each have an arc-shaped contour in the area of ​​the rear end 30 with the first coupling element 24 and in the area of ​​the front end 32 with the second coupling element 28. The arc-shaped design of the two ends 30, 32, which also extends to the other contours of the hook-in elements 26, causes the side edges 34, 36 to align parallel to each other when the busbar elements 18 are tensioned in the connection direction V by being pulled away from each other.

[0037] In the Fig. 3 and Fig. Figure 4 shows two further embodiments of busbar elements 18, wherein identical or at least functionally equivalent elements use the same reference numerals as in the Fig. 1 and Fig. 2 can be used.

[0038] The in Fig. The embodiment shown in section 3 essentially corresponds to the one described in the Fig. 1 and Fig. The embodiment shown in Figure 2 has a base body 20 and two hook elements 26, each formed at the longitudinal ends 30, 32. In this embodiment as well, the hook elements 26 are U-shaped in cross-section when viewed in a longitudinal section.

[0039] The in Fig. The embodiment shown in Figure 3 has the advantage that removing a busbar element 18 is particularly easy, as the busbar element 18 only needs to be moved in the width direction B marked with the double arrow, which is oriented perpendicular to the connection direction V.

[0040] Unlike the one in the Fig. 1 and Fig. In the embodiment shown in 2 with the arc-shaped ends 30, 32, it is the case that in Fig. In the embodiment shown in Figure 3, it is not necessary for the busbar element 18 to be elastically deformable in the longitudinal direction. To remove a busbar element 18 according to the embodiment shown in Figure 3, Fig. In the embodiment shown in Figure 3, only the friction to the hooking elements of the adjacent busbar elements 18, which interact with the hooking elements 26 of the busbar element 18 shown, needs to be overcome.

[0041] Fig. Figure 4 shows a further embodiment of a busbar element 18 according to the invention. In this embodiment, a bushing element 38 is formed as the first coupling element 24 and a plug-in element 40 as the second coupling element 28.

[0042] The bushing element 38 is formed by two spaced-apart wall sections 42, 44 – here: oriented parallel to each other – which form an opening 46 with a distance a at the longitudinal end.

[0043] The insertion element 40 is formed by two vertically projecting projections 48, 50. The height e in the region of the projections 48, 50 is greater than the distance a in the region of the socket element 38. However, the insertion element 40 is designed to fit the socket element 38 in such a way that it is possible to insert the insertion element 40 of one busbar element 18 into the socket element 38 of another identically designed busbar element 18 to create a force-fit connection. This can be achieved in particular by making the projections 48, 50 and / or the wall sections 42, 44 elastically deformable, allowing the effective height e in the region of the projections 48, 50 to be reduced and / or the distance a to be increased by widening the wall sections 42, 44.

[0044] Even if this is in the Fig. 3 and Fig. Not shown in Figure 4, radii or other modified designs may be provided in the area of ​​the coupling elements 24, 28 to improve application, reduce the risk of injury, create a positive-locking connection in addition to a friction-locking connection, and / or design the force level of a friction-locking connection as required. In particular, recesses aligned with the projections 48, 50 may be provided on the inside of the wall sections 42, 44, allowing the wall sections 42, 44 to spring back into place after elastic rebound when the insertion element 40 is inserted. Fig. The connection can spring back to the basic position shown in Figure 4. A connection can also be designed such that, after two busbar elements 18 have been mechanically pressed together, accidental separation of the two busbar elements by manual force is practically impossible. In this case, or if the connection of a plurality of busbar elements 18 is designed as a permanently holding connection due to sufficient positive locking and / or force locking, a plurality of busbar elements 18 can be pre-assembled into a longer chain, for example of 5, 8 or 10 busbar elements 18, and then connected to the cell poles 14 – like a plate known from the prior art – in particular by welding.

[0045] Preferably, the busbar elements 18 are designed such that a mechanical stress is applied in the connection direction V before the contact areas 22 are connected to the cell poles 14. This stress improves or establishes contact between the individual busbar elements 18 and enhances the electrical connection between them. In particular, a low-resistance connection between the individual busbar elements 18 should be established in this stressed state. The busbar elements 18 are then connected to the cell poles 14, particularly by welding.

[0046] As an alternative to applying a voltage in the connection direction V, the low-resistance connection can also be created by ensuring sufficient contact between a plug-in element 40 and a corresponding socket element 38 during the connection process. This can be ensured in particular by sufficiently large contact surfaces and a sufficiently high force for a corresponding friction-fit connection.

[0047] Alternatively or additionally, a low-impedance connection can also be achieved by using busbar elements 18, as described in the Fig. 1 and Fig. The two items shown are initially arranged at a 90° angle to each other and then pivoted into the position shown. Fig. 1. The position shown creates a large-area connection in the area of ​​the hook elements 26.

[0048] The features of the invention disclosed in the present description, the drawings, and the claims can be essential for realizing the invention in its various embodiments, both individually and in any combination. The invention can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art. Reference symbol list 10 battery cell casings 12 battery cells 14 cell poles 16 Top 18 Busbar element 20 basic shapes 22 Contact area 24 first coupling element 26 Hook element 28 second coupling element 30 rear end (bow-shaped) 32 front end (arc-shaped) 34 side edge 36 side edge 38 Bushing element 40 Insert element 42 Wall section 44 Wall section 46 Opening 48 lead 50 lead a distance bB Width of the busbar element B Latitude direction height in the area of ​​the wall sections hB Height of the busbar element IB Length of the busbar element V Connection direction

Claims

[1] Busbar element with a base body (20) having a planar contact area (22) for contacting a cell pole (14) of a battery cell (12), with a first coupling area having a first coupling element (24) and with a second coupling area having a second coupling element (28), wherein the first coupling element (24) and the second coupling element (28) are designed to be complementary to each other such that the first coupling element (24) can be connected to a second coupling element (28) of a second, identically designed busbar element (18) by friction and / or form locking, characterized by , that the base body (20) is formed in one piece with the first coupling element (24) and the second coupling element (28). [2] Busbar element according to the preceding claim, characterized by, that the first coupling element (24) and the second coupling element (28) are each arranged or formed at opposite ends (30, 32) of the base body (20). [3] Busbar element according to any of the preceding claims, characterized by , that the first coupling element (24) and the second coupling element (28) are designed in the same way. [4] Busbar element according to the preceding claim, characterized by , that the first coupling element (24) and the second coupling element (28) each have at least one hooking element (26) with a U-shaped or arc-shaped cross-section. [5] Busbar element according to one of claims 1 or 2, characterized by , that the first coupling element (24) is designed as a plug-in element (40) and the second coupling element (28) is designed as a bushing element (38) adapted to the plug-in element (40). [6] Busbar element according to the preceding claim, characterized bythat the bushing element (38) and / or the insertion element (40) have at least one elastically deformable section. [7] Arrangement of at least two busbar elements (18) according to one of claims 1 to 6 on at least two battery cells (12), each having a battery cell housing (10) and at least one cell pole (14) projecting from the battery cell housing (10), characterized by , that the two busbar elements (18) are connected to each other by means of interoperating coupling elements (24, 28) in a force-locking and / or form-locking manner and each of the busbar elements (18) is connected with its contact area (22) to a cell pole (14). [8] Arrangement according to the foregoing claim, characterized by, that a plurality of cell poles (14) of battery cells (12) are connected to each other via a plurality of busbar elements (18), wherein a separate busbar element (18) is arranged on each battery cell (12) and each busbar element (18) is connected to at least one other busbar element (18) in a form-fitting and / or force-fitting manner. [9] Method for connecting cell poles (14) of at least two battery cells (12) using at least two busbar elements (18) according to any one of claims 1 to 6, characterized by , that the two busbar elements (18) are connected to each other by force and / or form locking and the contact areas (22) of the busbar elements (18) are subsequently connected to the cell poles (14).

Images