Contacting device for connecting a plurality of battery cells

Abstract

The invention relates to a contacting device for connecting a plurality of battery cells (1), the contacting device having two current paths, which are electrically isolated from one another, and having receptacles (2) for battery cell end portions, wherein a first conductor (3a, 3b, 3c) for electrically contacting the positive terminals of the battery cells (1) in parallel forms the first current path and a second conductor (4a, 4b, 4c) for electrically contacting the negative terminals in parallel forms the second current path. In order to allow, despite a simple structure and a compact design, reliable parallel and series interconnection of the battery cells with the least possible conduction losses, an electrically insulating carrier plate (7) is arranged between the two conductors (3a, 3b, 3c, 4a, 4b, 4c), through which carrier plate, at least in part, a plurality of electrical connectors (8) in a distributed arrangement extend for the purposes of contacting, in series, the conductors (3a, 3b, 3c, 4a, 4b, 4c) opposite the carrier plate (7).

Description

[0001] Contacting device for connecting several battery cells

[0002] Technical area

[0003] The invention relates to a contacting device for connecting a plurality of battery cells, with two electrically insulated current paths and with receptacles for battery cell end sections, wherein a first conductor for the parallel electrical contacting of the positive poles of the battery cells forms the first current path, and a second conductor for the parallel electrical contacting of the negative poles forms the second current path.

[0004] State of the art

[0005] For connecting multiple battery cells in parallel, contacting devices are known that comprise printed circuit boards assigned to the positive and negative poles, each with an insulating layer between them (DE102011015620A1, US20190081309A1, WO2018071776A1). The cell poles of the battery cells are bonded to the respective printed circuit boards, particularly via wire connectors (wire bonding). The wire connectors extend through receptacles for battery cell end sections. To ensure the structural integrity of the device despite the delicate wire connectors, the printed circuit boards acting as inserts and the insulating film between them are usually overmolded with a plastic matrix forming a support structure.Aside from the fact that this involves a comparatively high level of design effort, not least due to the component tolerances and coordination that must be considered during design, the injection pressures often lead to mechanical damage to the wire connectors. To enable serial connection of the circuit boards while minimizing the risk of short circuits due to the exposed wire connectors, they are connected to each other at the edges via connecting conductors. However, this leads to increased current path lengths at these connection points, which in turn increases the line resistance and thus reduces the efficiency of the battery module.

[0006] Description of the invention

[0007] The invention is therefore based on the object of designing a contacting device of the type described at the outset in such a way that, despite simple structural conditions and a compact design, a reliable parallel and series connection of the battery cells is possible with the lowest possible line losses.

[0008] The invention achieves the stated object in that an electrically insulating carrier plate is arranged between the two conductors, which is at least partially penetrated by a plurality of distributed electrical connectors for serial contacting of the conductors opposite with respect to the carrier plate.

[0009] The invention is based on the consideration that a reliable serial connection between the two current paths with the shortest possible current paths is achieved by providing a plurality of electrical connectors, in particular distributed in a plane parallel to the carrier plate plane, which contact both conductors with one another via a connection path extending through the carrier plate. The electrical connectors preferably penetrate the carrier plate at least partially in the intermediate regions lying between the receptacles for the battery cell end sections with respect to the carrier plate plane. Particularly favorable design conditions arise if the conductors are each manufactured in one piece from a sheet metal and are fastened to opposite sides of the carrier plate, which is made in particular from plastic, to form a sandwich composite.This offers the advantage, with correspondingly thin conductor sheets in the range of 100 - 500 pm, that sufficient mechanical strength of the composite is achieved even with carrier plate thicknesses of approx. 1 - 2.5 mm, without the need for overmolding of the conductor tracks.

[0010] Particularly advantageous assembly conditions with reliable electrical contacting of the battery cell positive poles arise when the first conductor has contact tongues that at least partially penetrate the receptacles for a materially bonded electrical connection to each cell pole of the battery cells. The design as contact tongues offers the advantage that, when assembling a battery module with a contacting device according to the invention, the cell poles facing the carrier plate remain easily accessible via the receptacle, so that the cell poles can be materially bonded to the first conductor, in particular using welding processes. To further simplify the assembly process, it is recommended to design the contact tongues as spring tongues.

[0011] Preferably, a tongue section projects under prestress in the direction of the cell pole to be connected or, ideally, already contacts this under prestress, so that the subsequent joining process to form the material-locking connection can be carried out particularly easily.

[0012] Preferably, the first conductors and the contact tongues are made in one piece from a sheet metal, in particular as a stamped part. Such a design also creates the prerequisite for achieving relatively short current paths with a robust construction, namely both with regard to the parallel connection between adjacent cell poles and with regard to the series connection between one or more cell poles and the second conductor. The latter enables, for example, in the case of receptacles with a circular cross-section arranged in parallel rows staggered by a gap, a current path length L normalized to the cell pole spacing z of at most + (n - 1) along the row-parallel direction of the receptacles, where n corresponds to the number of battery cells in the current path. The cell pole spacing z specifies the sum of the diameter of the battery cells and the shortest distance between two adjacent battery cells.If, according to another design of the contacting device, the current path is normal to the series-parallel direction of the receptacles, for example, the current path length L normalized to the cell pole spacing z results in I * 7T V3 being at most — + —.

[0013] For safety reasons, it is recommended that the first conductor be fitted with fuses near the contact tabs. This electrically separates the defective battery cell from the first conductor and thus from the rest of the cell assembly in the event of an overcurrent. The placement of the fuse near the contact tabs further promotes the melting of the fuse, especially if hot gas escapes from the defective cell.

[0014] Although, in principle, it can be provided that the battery cells comprise a materially bonded connection to the second conductor on the casing side or at their battery cell shoulders for electrically contacting the second conductor with the battery cell end sections, particularly favorable design conditions arise if the second conductor has spring arms for encompassing the battery cell end sections on the casing side. Consequently, when connecting the battery cells to the contacting device, only materially bonded connections of the respective cell poles to the first conductor are required, whereas the spring arms enable a force- or form-fitting and thus detachable electrical connection of the battery cells to the second conductor. The spring arms themselves can, for example, be formed integrally with the second conductor or can also be materially bonded to the second conductor.In the case of cylindrical battery cells, contact springs can be provided in particular, which have spring arms projecting from a base integrally connected to the second conductor for circumferentially encompassing a battery cell end section.

[0015] In order to enable a reliable and simple electrical connection between two battery modules having contacting devices, it is proposed that the first and / or the second conductor have edge contacts projecting in the edge region of the conductor. If the conductors are manufactured in one piece from a sheet metal, the edge contacts can be formed in a particularly simple manner by corresponding punchings or cutouts in the edge regions. Particularly favorable assembly conditions also arise if the edge contacts are designed as contact tongues or contact fingers such that the respective edge contacts engage with one another in a force-fitting manner when two contacting devices are connected. This creates a detachable type of connection, so that in particular a materially bonded connection between the respective edge contacts of adjacent contacting devices can be omitted.

[0016] In order to be able to safely divert the hot gas escaping from a battery cell in the event of a fault in order to avoid thermal runaway and at the same time to largely protect the contact or connection points of adjacent battery cells from the escaping hot gas, it is proposed that a fire-resistant protective layer be arranged above the first conductor, which comprises recesses corresponding to the receptacles for the battery cell end sections, each at least partially closed by a cover. The covers are connected to the recesses via respective sol breaking points in such a way that in the event of outgassing from a battery cell, the cover can detach from the recess due to gas pressure. To form the predetermined breaking points, the protective layer, which can be made of fire-resistant paper or, in particular, mica, for example, can have corresponding perforations.

[0017] In this context, not only simple assembly conditions are achieved, but also, in particular, improved protection of neighboring battery cells in the case of an outgassing battery cell, if the carrier plate has retaining bodies arranged circumferentially around the respective receptacles and projecting in a detachment direction, which engage behind the respective recesses of the protective layer as stops acting counter to the detachment direction, in particular in a clamping manner. These features ensure, even at higher hot gas pressures, that only the cover associated with the affected battery cell detaches from the protective layer, without the entire protective layer being lifted in the detachment direction and thus exposing the unprotected receptacles of neighboring battery cells.

[0018] The invention also relates to a module comprising contacting devices and consisting of a plurality of battery cells, wherein the module comprises a plurality of module groups, each of which is assigned a contacting device. The module groups can, for example, each have a different number of battery cells. For favorable design conditions, a single common carrier plate and / or a single common protective layer can be provided in the case of a module with multiple contacting devices.

[0019] Brief description of the invention

[0020] The drawing shows an example of the subject matter of the invention.

[0021] Fig. 1 is an exploded view of contacting devices according to the invention,

[0022] Fig. 2 is a schematic oblique view of a module according to the invention with several contacting devices,

[0023] Fig. 3 is a section along the line III-III according to Fig. 2 on a larger scale, Fig. 4 is a section along the line IV-IV according to Fig. 3 also on a larger scale,

[0024] Fig. 5 is a plan view of a module according to Fig. 2 without a protective layer and Fig. 6 is a bottom view corresponding to Fig. 5.

[0025] Ways to implement the invention

[0026] Contacting devices according to the invention for connecting multiple battery cells 1 generally comprise receptacles 2 for battery cell end sections, as well as two electrically insulated current paths. A first conductor 3a, 3b, 3c forms the first current path for the parallel electrical contacting of the positive poles of the battery cells 1, and a second conductor 4a, 4b, 4c forms the second current path for the parallel electrical contacting of the negative poles. The indices a, b, c each refer to one of the three contacting devices shown in Fig. 1.

[0027] The first conductor 3a, 3b, 3c has contact tongues 5 that at least partially penetrate the receptacles 2 and are made of sheet metal in one piece with the respective first conductor 3a, 3b, 3c. The second conductor 4a, 4b, 4c also comprises spring arms 6, which are also made of sheet metal in one piece with the first conductor, for gripping the battery cell end sections on the jacket side.

[0028] The contacting devices according to Fig. 1 share both a common, electrically insulating carrier plate 7, which is arranged between the conductors 3a, 3b, 3c and 4a, 4b, 4c, and a common fire-resistant protective layer 9 arranged above the first conductor 3a, 3b, 3c.

[0029] According to the invention, the carrier plate 7 is at least partially penetrated by a plurality of distributed electrical connectors 8 for serially contacting the conductors 3a, 3b, 3c and 4a, 4b, 4c located opposite the carrier plate 7. This is illustrated in more detail in the following Figs. 3 and 4.

[0030] The protective layer 9 comprises recesses 10 corresponding to the receptacles 2 for the battery cell end sections, which are each partially closed by covers 11, leaving a partially circumferential gap that forms between the recesses 10 and the covers 11. The covers 11 are connected to the recesses 10 via respective sol-fracture points 12 such that, in the event of outgassing from a battery cell 1, the cover 11 can detach from the recess 10 due to gas pressure. In addition, the carrier plate 7 has holding bodies 13 arranged circumferentially around the respective receptacles 2 and protruding in a detachment direction A, which engage behind the respective recesses 10 of the protective layer 9 as stops acting counter to the detachment direction A. The holding bodies 13 penetrate the partially circumferential gaps that form between the recesses 10 and the covers 11.

[0031] For electrical connection to further contacting devices not shown in detail, both the first conductor 3a and the second conductor 4c have edge contacts 14a, 14c projecting in their respective edge regions.

[0032] As illustrated in the sectional view according to Fig. 3, the respective conductors 3 and 4 are fastened to the carrier plate 7 to form a sandwich composite, whereby a particularly high rigidity is achieved.

[0033] For the electrical connection of the first conductor 3 to a cell pole 15 of the battery cells 1, the corresponding contact tongues 5 are preferably welded to the cell poles 15, as is particularly illustrated in Fig. 4. Furthermore, the electrical connectors 8, which in the embodiment shown are manufactured in one piece with the first conductor 3, contact the conductor 4 opposite the carrier plate 7, wherein the connection is also preferably made by means of a material bond.

[0034] A module comprising several battery cells 1, as shown in particular in Figs. 2 to 6, has several module groups, each of which is assigned a contacting device. The different module groups, which in this case each comprise twelve battery cells, can be seen in Fig. 6 by the illustration of the second conductors 4a, 4b, and 4c, each of which is assigned to a separate contacting device.

Claims

Patent claims 1. Contacting device for connecting a plurality of battery cells (1), with two current paths that are electrically insulated from one another and with receptacles (2) for battery cell end sections, wherein a first conductor (3a, 3b, 3c) for the parallel electrical contacting of the positive poles of the battery cells (1) forms the first current path, and a second conductor (4a, 4b, 4c) for the parallel electrical contacting of the negative poles forms the second current path, characterized in that an electrically insulating carrier plate (7) is arranged between the two conductors (3a, 3b, 3c, 4a, 4b, 4c), which is at least partially penetrated by a plurality of distributed electrical connectors (8) for the serial contacting of the conductors (3a, 3b, 3c, 4a, 4b, 4c) that are opposite one another with respect to the carrier plate (7).

2. Contacting device according to claim 1, characterized in that the first conductor (3a, 3b, 3c) has contact tongues (5) which at least partially penetrate the receptacles (2) for the integral electrical connection to a respective cell pole (15) of the battery cells (1).

3. Contacting device according to claim 2, characterized in that the first conductor (3a, 3b, 3c) and the contact tongues (5) are made in one piece from a sheet metal.

4. Contacting device according to claim 2 or 3, characterized in that the first conductor (3a, 3b, 3c) has fuses in the region of the contact tongues (5).

5. Contacting device according to one of claims 1 to 4, characterized in that the second conductor (4a, 4b, 4c) has spring arms (6) for encompassing the battery cell end sections on the jacket side.

6. Contacting device according to one of claims 1 to 5, characterized in that the first conductor (3a, 3b, 3c) and / or the second conductor (4a, 4b, 4c) has edge contacts projecting in the edge region of the conductor (3a, 3b, 3c, 4a, 4b, 4c) for electrical connection to a further contacting device.

7. Contacting device according to one of claims 1 to 6, characterized in that a fire-resistant protective layer (9) is arranged above the first conductor (3a, 3b, 3c), which comprises recesses (10) corresponding to the receptacles (2) for the battery cell end sections, each at least partially closed by a cover (11), wherein the covers (11) are connected to the recesses (10) via respective break points (12) in such a way that in the event of outgassing of a battery cell (1), the cover (11) can detach from the recess (10) due to gas pressure.

8. Contacting device according to claim 7, characterized in that the carrier plate (7) has holding bodies (13) arranged circumferentially around the respective receptacles (2) and projecting in a detachment direction (A), which engage behind the respective recesses (10) of the protective layer (9) in a clamping manner or as stops acting counter to the detachment direction (A).

9. Module comprising a plurality of battery cells, with contacting devices according to one of claims 1 to 8, characterized in that the module comprises a plurality of module groups, each of which is assigned a contacting device.

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