Method for repairing a battery with multiple individual battery cells

Abstract

The invention relates to a battery (1) with a plurality of individual battery cells (2) which have battery poles (3, 4), wherein the battery poles (3, 4) of adjacent individual battery cells (2) are electrically conductively connected to one another via cell connectors (5) having material sections (8) made of an electrically conductive material. The battery according to the invention is characterized in that at least some of the cell connectors (5) have material sections (8) with a length which extends at least as far as one of the battery poles (3, 4) of the second but one individual battery cell (2) following the adjacent individual battery cell (2), wherein the additional length is electrically insulated and folded in a meandering or S-shape. In the event of a repair, the cell connector (5) can thus be separated and pulled to the second but one adjacent individual battery cell and reconnected to it. A defective individual battery cell (X) can thus be bridged.

Description

[0001] The invention relates to a method for repairing a battery with several individual battery cells according to the type defined in more detail in the preamble of claim 1.

[0002] A common design for batteries is to have several individual battery cells, each with battery terminals. Depending on the desired electrical wiring, the battery terminals of adjacent individual battery cells are electrically connected to each other via material sections of cell connectors.

[0003] DE 10 2014 216 813 A1 describes such a cell connector, which is placed between individual battery cells and contacts the corresponding battery terminals of the individual battery cells to create the desired connection. The connection can be realized, for example, by welding.

[0004] Another alternative for a battery with a cell connector for connecting the individual battery cells is also known from WO 2013 / 131548 A1. The special feature is that, in addition to their regular structure, the cell connectors have tapered sections that act as electrical fuses.

[0005] Another variant of cell connectors is known, for example, from DE 10 2009 035 465 A1. Here, the cell connectors are integrated into a circuit board that is placed on the individual battery cells.

[0006] DE 10 2014 018 957 A1 also discloses a unit for tapping individual cell voltages. Elastic connecting elements can be provided between two such units to compensate for positional tolerances.

[0007] US 2022 / 0 158 309 A1 shows a length-adjustable electrical contacting element which is electrically insulated by a plastic sheath which is also variable in length.

[0008] In practice, such batteries—and this applies particularly, but not exclusively, to highly dynamically loaded vehicle batteries in electric vehicles, hybrid vehicles, or the like—can fail if individual battery cells are defective. The designs described above then only allow for battery replacement, as no practical repair concepts are available. Typically, an entire battery is therefore constructed from individual modules, so that only one of the modules—and thus ultimately only a portion of the individual battery cells installed within the battery—needs to be replaced. However, this modular design makes the battery unnecessarily expensive, heavy, and large, which is also disadvantageous.

[0009] The object of the present invention is to disclose a repair method for such a battery.

[0010] According to the invention, this object is achieved by a method for repairing such a battery according to claim 1. An advantageous embodiment of the repair method results from the dependent subclaims.

[0011] The method according to the invention for repairing a battery provides individual battery cells whose battery poles are electrically connected to one another in the desired type of electrical connection via material sections of cell connectors.

[0012] In the battery, at least some - preferably all - of the cell connectors have material sections with a length that extends at least to one of the battery poles of the next-to-next battery cell, with the additional length being electrically insulated and folded in a meandering shape. In the battery, one material section of the cell connector is therefore connected to two battery poles, for example two battery poles of opposite polarity on adjacent battery cells. Nevertheless, an additional length of material is provided, which is folded in a meandering or S-shape and is electrically insulated. This additional material length is not required in the regular structure of the battery. However, it is dimensioned such that the material section with the additional length extends to the battery poles of the next-to-next battery cell, if necessary.

[0013] The method according to the invention for repairing such a battery provides, in the case of a defective individual battery cell, that the connection between the battery poles of the defective individual battery cell and the respective cell connectors is severed as close as possible to the respective battery pole. As close as possible or adjacent in this sense means that no more cell connector material than necessary is left on the respective battery pole. For example, in the case of a cell connector attached using a laser welding process with an I-seam, the cell connector can be severed immediately next to the weld seam, still in the area of ​​the respective battery pole. Subsequently, the respective cell connector is pulled to the corresponding battery pole of the next but one adjacent individual battery cell, whereby the additional length of the material section unfolds and typically comes to lie above the defective individual battery cell.The cell connector is then connected to the corresponding battery terminal of the next but one adjacent battery cell, so that the defective battery cell is bridged in the battery's electrical circuitry.

[0014] As already mentioned above, the connection can be restored, particularly through laser welding. If necessary, the electrical insulation of the material section can be further removed in the area where it is reconnected to the battery terminal of the next-but-one adjacent cell, if there is insufficient remaining space to create a suitable connection. Depending on the material used for electrical insulation, this can be achieved, particularly with laser welding, by melting or evaporating this material without any additional intermediate step.

[0015] Using such a repair process, a defective individual battery cell within a battery or battery module can be bypassed very easily and efficiently. This provides a simple repair option. Ultimately, this eliminates the need for individual modules, since even in a large battery containing those battery cells that would otherwise be arranged in four individual modules, the possibility of repairing a defective individual battery cell allows the battery to be largely preserved.

[0016] According to a further advantageous embodiment of the method, the electrical insulation can be achieved by partially covering the cell connector with plastic, and in particular by partially melting the material section or the additional length of the material section, so that the ends to be contacted are free of electrical insulation. Such a plastic sheathing can be manufactured relatively easily, e.g. by applying a coat of paint. Depending on the plastic used, sufficient electrical insulation can be ensured, which is not impaired over the entire length even by spot welding, for example by laser welding, of the ends of the cell connector to the battery poles. Alternatively, welding can be easily carried out in the event of a repair by melting the plastic material at specific points in the connection area.

[0017] Another very advantageous embodiment provides for the cell connectors to each have a material strip designed to electrically connect the battery terminals of the same polarity of adjacent individual battery cells, with a material section branching off from the material strip for each battery terminal. This design thus creates a cell connector that can be used to connect at least two adjacent individual battery cells in parallel. In particular, more than two adjacent individual battery cells can also be connected in parallel.Since this parallel connection does not have to be bridged in the event of a fault of a defective individual battery cell, it is sufficient if the material sections with the additional length, i.e. the length reservoir, branch off from this material strip in the event of a repair and connect the parallel-connected individual battery cells in series with another group of parallel individual battery cells via one or, in particular, several parallel connectors.

[0018] The cell connectors themselves can be made of copper or a copper alloy, or alternatively, they can be made of aluminum or an aluminum alloy. In particular, hybrid materials, such as those known in principle in the prior art, are also conceivable.

[0019] Since the total number of individual battery cells is comparatively high, especially in traction batteries such as those used for electrically powered vehicles, bridging a single battery cell represents only a very small disadvantage in terms of battery performance and capacity, which can easily be accepted in order to achieve a much longer battery life through repairability.

[0020] Further advantageous embodiments also emerge from the exemplary embodiments, which are described in more detail below with reference to the figures.

[0021] Showing: Fig. 1 is an exploded view illustrating a first embodiment of the battery for the method according to the invention; Fig. 2 the structure according to Fig. 1 in assembled state; Fig. 3 a first possible embodiment of the arrangement of the additional length of the material strip; Fig. 4 a second possible embodiment of the arrangement of the additional length of the material strip; Fig. 5 a representation analogous to that in Fig. 2 with a defective single battery cell; Fig. 6 the structure according to Fig. 5 in the state repaired according to the method of the invention. Fig. 7 an exploded view analogous to that in Fig. 1 with an alternative cell connector; and Fig. 8 the structure according to Fig. 5 in assembled state.

[0022] In the presentation of the Fig. 1, 2 and 5 to 8 each show a section of a battery 1 (not shown in its entirety), which comprises five individual battery cells 2, of which only one is provided with a reference numeral. The individual battery cells 2, of which only the upper part is shown, are designed purely as examples as round cells in the course of the flexibility of the battery with several individual battery cells and the method for repair with regard to various battery cell formats. They have their Fig. 1 on the left with + the positive battery terminal 3 in the middle, while the surrounding housing of the individual battery cells 2 forms the negative battery terminal 4. Typically, these individual battery cells 2 are now connected to each other via cell connectors 5. In the exploded view of the Fig. 1, four such cell connectors 5 are visible above the section of the battery 1; here again, only one of the cell connectors 5 has the reference numerals. These cell connectors 5 are then placed with one end onto the negative battery terminal 4 of one single battery cell 2 and with their other end onto the positive battery terminal 3 of the adjacent single battery cell 2. A connection is then realized by laser welding, which is shown in the illustration of the Fig. 2 can be seen by the indicated laser beam 6. So far, only the cell connector 5 shown on the left has been welded accordingly; the others have only been placed in place and are waiting for the welding process.

[0023] Each of the cell connectors 5 now has two connecting sections 7 intended for connection to the battery terminals 3, 4 and a material section 8 located therebetween. In the illustrations of the Fig. 1 and Fig. 2 it can be seen that this material section 8 is designed to be much longer than it would actually be necessary to connect the respective battery poles 3, 4 of adjacent individual battery cells 2. This additional material length of the material section 8 is folded in an S-shape, as is the case, for example, in the Fig. 1, Fig. 2, Fig. 3 and Fig. 5 ff. Alternatively to this S-shaped folded configuration of the cell connector 5, which is shown in the illustration of Fig. 3 can be seen again in a side view, the material section 8 between the two connecting sections 7 of the cell connector 5 could also, as shown in the schematic representation of the Fig. 4, are folded in a meandering pattern. The type of folding is fundamentally irrelevant, so the two design variants shown here are each to be understood only as examples. Relevant to the function is that an additional length of material or a material reservoir is present in the material section 8, which is large enough that, if necessary, the cell connector 5 can also be connected to the battery terminals 3, 4 of the next but one adjacent single battery cell 2.

[0024] The one in the Fig. 1 and Fig. The structure of the section of the battery 1 shown in Figure 2 now shows the conventional structure as it occurs during assembly of the battery 1. The additional length of the material section 8 is held in reserve as a length reservoir by folding or a meandering arrangement of the material, but does not impair the connection of the battery terminals 3, 4 of adjacent individual battery cells 2. If, for example, during production or later during operation of the battery 1 in the field, one of the individual battery cells 2 is defective, the battery 1 can now be very easily repaired. In the illustration of the Fig. 5 is the Fig. 2 is taken up again. The centrally located single battery cell 2, designated X, is now said to be defective. In a conventional design, the battery 1 would now have to be replaced as a whole. However, here there is the possibility of repair. The cell connector 5 connecting the defective single battery cell X with the single battery cell 2 located diagonally behind it to the left is severed along the dashed lines designated Y, particularly in the respective connecting section 7. It can then be removed. At the same time, the cell connector 5 connecting the front right-hand single battery cell 2 with the defective single battery cell X is severed in the area of ​​the positive battery pole 3 of the defective single battery cell X, as close as possible to the connection formed by the weld seam, particularly also in the corresponding connecting section 7. This is shown in the illustration of Fig. 5 is designated Z. This cell connector 5 remains connected to the negative pole 4 of the single battery cell 2 shown at the front left and is now pulled in the direction of the single battery cell 2 located at the rear left, for which purpose the material reservoir previously present in the material section 8 due to the S-shaped fold is pulled out. Since this material section 8 is electrically insulated, it can be pulled over the pole(s) 3, 4 of adjacent single battery cells 2, here in particular the defective single battery cell X, without fear of a short circuit or the like. The material length of the material section 8 of the cell connector 5 is now sufficient to pull the remainder of the connection area 7 remaining after the separation onto the positive battery pole 3 of the single battery cell 2 located at the rear left, as shown in Fig. 6. There, it can be reconnected to the battery terminal 3 via a laser beam 6, or in principle via another type of connection technology. In the structure of the battery 1, the defective single battery cell X is now bridged without the repair requiring any external material expenditure.

[0025] In addition to the simple strip-shaped cell connectors 5 in the illustrations of the Fig. 1 to 6, it is of course also conceivable in principle to design the cell connector 5 differently. From the prior art mentioned at the beginning, it is known that cell connectors can also electrically connect the poles 3, 4 of several adjacent individual battery cells 2 in parallel, before they then interconnect the groups of parallel individual battery cells 2 in electrical series. In the illustration of Fig. 7 are analogous to the representation in Fig. 1 shows two such cell connectors 5. They each comprise a material strip designated 9, which is intended for connecting the individual battery cells 2 to be connected in parallel, or in this case the negative battery poles 4 thereof. From the respective connecting sections, also designated 7 here, a material strip 8 then branches off in the manner already described above, whereby this strip is again folded in an S-shape and provides an additional length of material. This material section 8 of the cell connector 5 is then connected, as already described at the beginning, to the positive battery poles 3 of further adjacent individual battery cells in order to implement the desired circuit, in this case a combination of the parallel connection of two individual battery cells and a series connection of these blocks.

[0026] Here, too, the corresponding repair concept can now be applied analogously to the description in the Fig. 5 and Fig.6 be implemented.

Claims

[1] Method for repairing a battery (1) with a plurality of individual battery cells (2) which have battery poles (3, 4), wherein the battery poles (3, 4) of adjacent individual battery cells (2) are electrically conductively connected to one another via cell connectors (5) with material sections (8) made of an electrically conductive material, wherein at least some of the cell connectors (5) have material sections (8) with a length which extends at least to one of the battery poles (3, 4) of the next but one individual battery cell (2) following the adjacent individual battery cell (2), wherein the additional length is electrically insulated and folded in a meandering or S-shape, in the case of a defective individual battery cell (X), for which purpose the connections between the battery poles (3, 4) of the defective individual battery cell (X) and the respective cell connectors (5) are severed close to the respective battery poles (3, 4), after which one of the cell connectors (5) is extended to the corresponding battery pole (3,4) the next but one adjacent battery cell (2) is pulled and reconnected to it. [2] Method according to claim 1, characterized by that the connection is realized by laser welding. [3] Method according to claim 1 or 2, characterized by that in the area of ​​the new connection the electrical insulation is removed from the material section (8). [4] Method according to one of the preceding claims, characterized by that a partial plastic sheath of the cell connector (5) is used as electrical insulation. [5] Method according to one of the preceding claims, characterized by that the cell connectors (5) each have a material strip (9) which is designed for the electrical connection of the battery poles (3, 4) of the same polarity of adjacent individual battery cells (2), wherein a material section (8) branches off from the material strip (9) for each battery pole (3, 4). [6] Method according to one of claims 1 to 5, characterized by that cell connectors (5) are used which comprise copper or a copper alloy. [7] Method according to one of claims 1 to 5, characterized by that cell connectors (5) are used which comprise aluminium or an aluminium alloy.

Images