Connecting element for electrically connecting two battery cells or battery modules and method for manufacturing such a connecting element

Abstract

Connecting element (10) for electrically connecting two battery cells or battery modules, wherein the connecting element (10) comprises two tabs (20, 30) which can each be attached to a battery cell or battery module in a mounting area (21, 31), and a flexible area (40) arranged between the two tabs (30, 30) which has a corrugated profile and extends in the longitudinal direction of the connecting element (10), wherein the flexible area (40) of the connecting element (10) has a material thickness that is less than the material thickness of the tabs (20, 30), characterized in that the flexible area (40) is wider than the tabs (20, 30), so that a current flowing through the connecting element (10) has the same current density in the flexible area (40) and in the tabs (20, 30).

Description

[0001] The present invention relates to a connecting element for electrically connecting two battery cells or battery modules, wherein the connecting element comprises two tabs, each of which can be attached to a mounting area on a battery cell or battery module, and a flexible area arranged between the two tabs, which has a corrugated profile and extends in the longitudinal direction of the connecting element. The invention also relates to a method for manufacturing a connecting element for electrically connecting two battery cells or battery modules. Furthermore, the invention relates to a battery system with multiple battery cells and / or multiple battery modules, each comprising at least one battery cell, wherein at least two battery cells and / or at least two battery modules are connected to one another by means of a connecting element. State of the art

[0002] To increase the voltage level or current of lithium-ion batteries, individual battery cells are connected in series or parallel to form battery modules. These battery modules can then be interconnected. This connection is typically achieved using cell or module connectors, which are referred to below as connectors or connecting elements.

[0003] In the Fig. Figure 1 shows such a connector 10, known from the prior art. The connector 10 can be configured as a double tab with a flexible section 40 in the form of a double shaft. The double tab comprises a first tab 20 and a second tab 30, and the flexible section 40 extends along the longitudinal direction of the connector 10 between the first tab 20 and the second tab 30. The tabs 20, 30 are attached to the battery cells or battery modules in a mounting area 21, 31 by means of an interface (not shown), for example, by screws or by welding. The length l of the tabs depends on the installation position. The cross-section of the connector 10 is usually uniform over its entire length, which is defined in the Fig. 1 extends along the x-direction, the width of connector 10 extends in the Fig. 1 along the y-direction. For the sake of completeness, in the Fig. 1 The z-direction is also shown.

[0004] Furthermore, a battery pack is known from document DE 10 2010 043 885 A1, the cells of which are connected by means of several cell connecting flat conductors. The cell connecting flat conductors are preferably realized in the form of a stamped grid made of a nickel sheet or a metal or alloy sheet with a nickel coating, for example, a steel sheet with a nickel coating. The cell connecting flat conductors are flat or planar and are arranged accordingly on the cells in a uniform manner.

[0005] The conventional battery pack also includes several flat conductors for the cell connections. These are preferably designed as flexible printed circuit boards. The flat conductors are connected to the cell terminals at their contact points by screw or weld connections and serve as sense lines. The flat conductors for the cell connections can be thicker than the flat conductors connecting the cells, for example, by at least a factor of two to three, allowing the current from the battery pack to be conducted without significant losses. A disadvantage of this design is that, due to their considerable thickness, which guarantees high conductivity, the flat conductors for the cell connections have limited flexibility and can therefore only compensate for mechanical cell displacements to a limited extent. This also limits the mechanical resilience of the battery pack under external mechanical stress.

[0006] State of the art in this regard includes, for example, the publications DE 20 2010 012 555 U1 and DE 10 2010 031 380 A1. Disclosure of the invention

[0007] According to the invention, a connecting element is provided for electrically connecting two battery cells or battery modules. The connecting element comprises two tabs, each of which can be attached to a battery cell or battery module in a mounting area, and a flexible area arranged between the two tabs, which has a wave-like profile and extends in the longitudinal direction of the connecting element. The flexible area of ​​the connecting element has a material thickness that is smaller or thinner than that of the tabs.

[0008] Furthermore, according to the invention, a method for manufacturing a connecting element for electrically connecting two battery cells or battery modules is provided. The connecting element comprises two tabs, each of which can be attached to a battery cell or battery module in a mounting area, and a flexible area arranged between the two tabs, which has a corrugated profile and extends in the longitudinal direction of the connecting element. The connecting element is provided with a flexible area having a material thickness that is less than that of the tabs, the reduced material thickness of which is achieved by machining or non-machining material removal on one or both sides.

[0009] By reducing the material thickness in the flexible area of ​​the connecting element or connector according to the invention, the flexibility of the connecting element or connector according to the invention is increased in all directions. The flexibility of the connector according to the invention is thereby increased particularly in its longitudinal direction (in the illustration from the Fig. 1 in the x-direction). A significant advantage is that the required strength of the connector according to the invention is nevertheless maintained in the fastening area. This is not possible according to the current state of the art.

[0010] Due to the reduced material thickness of the connector according to the invention in its fastening area, smaller bending radii can be achieved. This also reduces the installation space required for a connector according to the invention.

[0011] A key advantage of the invention is that mechanical cell or module displacements occurring in a battery system can be better compensated for by means of the connecting elements or connectors, each with increased compliance. This also significantly increases the mechanical load-bearing capacity of the battery system, e.g., from external loads acting on the system.

[0012] In particular, the flexible area of ​​the connecting element is designed as a double shaft.

[0013] According to the invention, the flexible area of ​​the connecting element according to the invention is designed to be wider than the tabs in such a way that a current flowing through the connecting element has the same current density in the flexible area and in the tabs.

[0014] In other words, the connector according to the invention has a reduced thickness in its flexible section, particularly in its flexible section shaped as a double shaft. To achieve the same current density in the flexible section as at the ends, the width of the connector must be increased accordingly in this section. If this is not necessary, the width of the connector can also be kept constant along its entire length.

[0015] In a further preferred embodiment of the invention, the connecting element is provided with such a cross-sectional profile that the current density of a current flowing through the connecting element assumes a predetermined or a desired profile.

[0016] In other words, the minimum cross-section of the connector according to the invention depends on the current flow occurring in an application. This primarily prevents the conductivity of the connector according to the invention from being undesirably limited due to an insufficient cross-section.

[0017] In a further particularly advantageous embodiment of the invention, at least a portion of the flexible section of the connecting element according to the invention is formed from such a material and has a material thickness such that the smallest achievable bending radius or the bending radius of the portion of the flexible section falls below a first predetermined threshold. Preferably, the flexible section of the connecting element is bent, at least in a portion, such that the bending radius of the portion exceeds a second predetermined threshold.

[0018] Thus, the minimum bending radii of the connector according to the invention depend on the material used and the material thickness of the connector, in particular the sheet thickness of a sheet used to form the connector. Due to the reduced material thickness of the connector according to the invention in the flexible area, smaller bending radii are possible with the connectors according to the invention than with connectors known from the prior art. As a result, the connectors according to the invention also require only a comparatively small installation space.

[0019] Furthermore, the largest possible bending radii should be selected for the flexible area of ​​the connector according to the invention, because this results in greater flexibility of the connector. The bend line that forms when a tab is twisted is thus closer to the axis of rotation. The closer the two lines are to each other, the closer one gets to a straight sheet, which, from a strength perspective, has the lowest resistance to twisting.

[0020] Furthermore, the connecting element according to the invention is preferably made of an electrically conductive material, in particular of a sheet metal or an aluminum and / or copper alloy. The connecting element according to the invention can also be made, at least in the flexible area, of a material such that the flexible area can be formed by machining or non-machining, either on one or both sides.

[0021] In a particularly advantageous embodiment of the invention, the material thickness of the flexible area is reduced by removing material in such a way that the flexible area has a predetermined or desired flexibility everywhere.

[0022] Thus, the reduction of the material thickness or the material strength of the connector in the flexible area can be achieved by machining or without machining. However, care must be taken to ensure that no significant work hardening of the material occurs. Preferably, the connectors according to the invention are manufactured from a highly electrically conductive and readily formable material, for example, an aluminum alloy or a copper alloy.

[0023] Furthermore, according to the invention, a battery with several battery cells and / or several battery modules, each comprising at least one battery cell, is provided. At least two battery cells and / or at least two battery modules are electrically connected to each other by means of the connecting element according to the invention.

[0024] The battery according to the invention is in particular a lithium-ion battery.

[0025] The invention also provides a vehicle with a battery.

[0026] Advantageous embodiments of the invention are specified in the dependent claims and described in the description. Drawings

[0027] Exemplary embodiments of the invention are explained in more detail with reference to the drawings and the following description. The drawings show: Fig. 1 a connecting element known from the prior art for electrically connecting battery cells or battery modules, and Fig. 2 a connecting element for electrically connecting battery cells or battery modules according to a first embodiment of the invention.

[0028] Fig. Figure 2 shows a connecting element (connector) 10 according to the invention for electrically connecting battery cells or battery modules according to a first embodiment of the invention.

[0029] The one in Fig. The connecting element shown in Figure 2 comprises a first tab 20, a second tab 30, and a flexible section 40, which has a corrugated profile and extends along the longitudinal direction of the connecting element 10 between the first tab 20 and the second tab 30. The tabs 20, 30 are attached to the battery cells or battery modules (not shown) in a mounting area 21, 31, respectively, by means of an interface (not shown), for example, by screws or welding. The length l of the tabs 20, 30 depends on the desired installation position of the connecting element 10 according to the invention. The connecting element 10 according to the invention has a smaller material thickness in the flexible section 40 than otherwise.The exact appearance of the connecting element, in particular the wave-shaped profile of the connecting element 10 in the flexible area 40, results from the conditions suitable for an application and / or from the installation situation.

[0030] From the Fig. Figure 2 shows that very small bending radii are possible in the sub-areas 41 and 42 of the flexible area 40 of the connecting element 10 according to the invention. As a result, the required installation space for connecting elements 10 according to the invention is significantly smaller than for conventional connecting elements.

[0031] The cross-section of the in the Fig. The length of the connecting element 10 according to the invention, as shown in Figure 2, is the same over its entire length. In the illustration, the length of the connecting element 10 extends from the Fig. 2 along the x-direction. The width of the connecting element 10 extends in the representation from the Fig. 2 along the y-direction. For the sake of completeness, in the Fig. 2. The z-direction is also shown.

Claims

[1] Connecting element (10) for electrically connecting two battery cells or battery modules, wherein the connecting element (10) comprises two tabs (20, 30) which can each be attached to a battery cell or battery module in a mounting area (21, 31) and a flexible area (40) arranged between the two tabs (30, 30) which has a corrugated profile and extends in the longitudinal direction of the connecting element (10), wherein the flexible area (40) of the connecting element (10) has a material thickness that is less than the material thickness of the tabs (20, 30), characterized by , that the flexible area (40) is wider than the tabs (20, 30), so that a current flowing through the connecting element (10) has the same current density in the flexible area (40) and in the tabs (20, 30). [2] Connecting element (10) according to claim 1, wherein the flexible area (40) of the connecting element (10) is designed as a double shaft. [3] Connecting element (10) according to one of the preceding claims, wherein the connecting element (10) is provided with a cross-sectional profile such that the current density of a current flowing through the connecting element (10) assumes a predetermined profile. [4] Connecting element (10) according to one of the preceding claims, wherein at least a partial area (41, 42) of the flexible area (40) is formed from such a material and has such a material thickness that the smallest achievable bending radius or the bending radius of the partial area (41, 42) of the flexible area (40) falls below a first predetermined threshold value and / or the flexible area (40) is bent in at least one partial area (41, 42) such that the bending radius of the partial area (40) exceeds a second predetermined threshold value. [5] Connecting element (10) according to one of the preceding claims, wherein the connecting element (10) is made of an electrically conductive material, in particular of a sheet or of an aluminium and / or copper alloy and / or the connecting element (10) is made of a material such that the flexible area (40) can be formed by machining or non-machining one- or two-sided material removal. [6] Method for manufacturing a connecting element (10) for electrically connecting two battery cells or battery modules, wherein the connecting element (10) comprises two tabs (20, 30) which can each be attached to a battery cell or battery module in a mounting area (21, 31), and a flexible area (40) arranged between the two tabs (20, 30) which has a corrugated profile and extends in the longitudinal direction of the connecting element (10), wherein a connecting element (10) is provided with a flexible area (40) having a material thickness less than that of the tabs (20, 30), characterized by, that the flexible area (40) is wider than the tabs (20, 30), so that a current flowing through the connecting element (10) has the same current density in the flexible area (40) and in the tabs (20, 30), the smaller material thickness of the flexible area (40) being achieved by machining or non-machining material removal on one or both sides. [7] Method according to claim 6, wherein the thickness of the flexible area (40) is reduced by removing material such that the flexible area (40) has a predetermined flexibility everywhere. [8] Battery comprising multiple battery cells and / or multiple battery modules, each comprising at least one battery cell, characterized by , that at least two battery cells and / or at least two battery modules are electrically connected to each other by means of a connecting element (10) according to one of claims 1 to 5. [9] Motor vehicle, in particular hybrid or electric vehicle, with a battery according to claim 8, wherein the battery is connected to a powertrain of the motor vehicle.

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