Cell assembly and high-voltage storage device comprising cell assembly

Abstract

The invention relates to a cell assembly of a high-voltage storage device. The cell assembly has a plurality of cells (14), wherein each cell (14) has a cell terminal (50) having a first pole (28), said cell terminal being formed by a protrusion (48), and a second pole (30), which forms a cell housing (54). The cell assembly (10) additionally comprises connecting conductors (16) which electrically connect the cell terminals (50) and / or second poles (30) together. The connecting conductors (16) are secured to the cell terminals (50) and / or second poles (30) to be connected and are secured at least to additional holding points (60) on another component. The invention additionally relates to a high-voltage storage device comprising such a cell assembly.

Description

[0001] Cell composite and high-voltage storage with cell composite

[0002] The invention relates to a cell assembly of a high-voltage storage device with several cells and to a high-voltage storage device with such a cell assembly.

[0003] High-voltage storage systems typically comprise a large number of battery cells combined in a cell array. Such high-voltage storage systems are used, for example, in motor vehicles, where typically four to six cells are combined in a parallel array. The cells are preferably vertical round cells, with the individual round cells connected to each other via their terminals. The individual terminals are usually connected via an electrical connecting conductor.

[0004] To ensure thermal safety, the electrical connecting conductors are typically equipped with a fuse, particularly an overcurrent fuse, to minimize the effects of a thermal event. These fuses are specifically designed to prevent the thermal event from propagating. Isolating elements such as wire bonds are typically used for this purpose. However, such a fuse is complex.

[0005] During a thermal event, such as a short circuit, the battery cell heats up due to the resulting temperatures, resulting in excess pressure within the battery cell. The mechanical load caused by this excess pressure can damage the electrically insulating seal located between the two poles of a cell in the area of ​​a cell terminal. The electrically insulating seal is typically made of polymers such as epoxy mold compounds (EMC), polyphenylene sulfide (PPS), or perfluoroalkoxy (PFA).

[0006] Due to the heat generated in the battery cell, the connecting conductor expands and exerts a force on the cell terminal, which transfers this force to the electrically insulating seal. Additional measures must be taken to prevent a short circuit. This short circuit represents a second thermal event, which can release temperatures in the range of 400 to 500°C. State-of-the-art fuses are activated during the second thermal event to prevent thermal runaway, preventing the first or second thermal event from spreading to the surrounding battery cells.

[0007] It is an object of the invention to prevent the occurrence of the second thermal event within the high-voltage storage device.

[0008] The object is achieved according to the invention by a cell assembly of a high-voltage storage device. The cell assembly has a plurality of cells, each cell having a cell terminal of a first pole formed by an extension and a second pole forming a cell housing. The cell assembly also comprises connecting conductors that electrically connect the cell terminals and / or second poles to one another. The connecting conductors are attached to the cell terminals and / or poles to be connected and are attached to another component at least at additional stops. In other words, the connecting conductor is supported on another component, such that the expansion of the connecting conductor is restricted. This minimizes the mechanical load on the cell terminal and reduces relative movement between the cell terminal and the second pole.In particular, the relative displacement between the two poles is limited to such an extent that a short circuit or a thermal event is prevented.

[0009] According to a preferred embodiment, the cells are round cells. Each of these round cells has an opening in the cell housing through which the cell terminal extends. Thus, an opening edge of the cell housing opening laterally encloses the cell terminal. To electrically insulate the cell terminal from the cell housing, a cell seal is arranged between the cell terminal and the opening edge.

[0010] In particular, the connecting conductor is attached to the second pole on the side of the respective cell and contacts this second pole there on which the first pole is also located. Thus, the connecting conductor(s) can be located on the same side of the cells and do not have to extend along the opposite side of the cells. Preferably, the connecting conductor is attached to a carrier board and / or a cover of the cells. Thus, no additional parts are required to support or attach the connecting conductors, thereby preventing an increase in production costs. In particular, the carrier board and the cover are made of a material with a low thermal coefficient, so that expansion of these components is not significant compared to the connecting conductors.

[0011] According to one embodiment, the stops are formed by a recess. The recess is designed to accommodate a projection of the additional component or a fixing part that is locked to the additional component. The connecting conductors are thus preferably attached to the additional components by a form-fitting connection. This enables reversible attachment, allowing the cell, connecting conductors, or cell seals to be replaced, thus increasing the service life of the cell assembly.

[0012] According to an alternative embodiment, the stops are formed by a projection, in particular a pin, on the connecting conductors. The projection is designed to engage a recess in the additional component. Additionally or alternatively, the connecting conductors are riveted to the additional component. Riveting also ensures that the fastening between the connecting conductors and the additional component does not accidentally come loose.

[0013] Preferably, an overload protection device, in particular a fuse, is also provided on the connecting conductors. The overload protection device can break a connection between the connecting conductor and the cell contact system if a predetermined reference temperature is exceeded. The overload protection device thus serves to prevent the propagation of a thermal event.

[0014] The overload protection device is preferably designed as a constriction on the connecting conductor. The constriction can be a resilient section of the connecting conductor, which gives the connecting conductor a wave-like structure when viewed from the side. According to one embodiment, the connecting conductors each consist of a sheet metal element, wherein the sheet metal element has at least one embossing. The sheet metal element is, in particular, an electrically conductive material, thus ensuring a reliable electrical connection between the cell terminals and / or second poles. The embossing can, in particular, be provided at the constrictions that provide the overload protection device. In addition, the embossing serves to reinforce the connecting conductors, thereby minimizing expansion of the connecting conductors due to heat and consequently reducing the risk of a short circuit.

[0015] The connecting conductors may have a wave-shaped section in plan view, from which freely projecting contact arms protrude. These freely projecting contact arms are attached to the cell terminals and / or poles, with stops provided on the contact arms. In particular, if the stops are provided on the contact arms in such a way that they rest on the cell housing, relative movement between the cell terminal and the cell housing can be avoided. With such support of the contact arms, the extension of the connecting conductor in the region of the cell terminal is minimized, thereby reducing the mechanical load on the cell terminal. Accordingly, the resulting relative displacement between the cell terminal and the opening edge is minimal.

[0016] Additionally, supporting the stops on the cell casing can counteract bulging of the cell casing, preventing further short circuits. Such bulging of the cell casing can be caused by increased pressure within the cell and, if the pressure is sufficiently high, can also trigger a short circuit.

[0017] The wave-shaped section is also ideal for electrically connecting round cells in two parallel, adjacent cell rows, as the round cells in adjacent rows are offset from each other and extend into the spaces between adjacent round cells in neighboring rows. Thus, the wave shape allows one or more round cells in one cell row to be connected to one or more round cells in a neighboring cell row or even to a more distant cell row. The wave shape also provides elasticity. Alternatively, the cells can also be pouch cells or prismatic cells. However, due to their geometry, round cells are preferred.

[0018] According to one embodiment, the connecting conductors are multi-layered, wherein the connecting conductors in particular comprise interconnected plates. The material of one plate has an expansion coefficient of 0 K' 1or a negative coefficient of expansion, while the other plate is made of an electrically conductive material. In other words, the connecting conductor is preferably made of a bimetal, with two layers rolled together. A first layer serves to establish electrical contact between the individual cells by contacting the cell terminals and / or second poles of neighboring cells. The second layer, on the other hand, is designed to stiffen the connecting conductor and counteract the expansion of the first layer. Accordingly, the second layer has a low or negative coefficient of expansion, but preferably an expansion coefficient of 0 K'. 1The second layer can be an iron-nickel alloy, for example. By stiffening the connecting conductor, even when the cell heats up, the connecting conductor expands only to a limited extent, thus preventing mechanical contact between the cell terminal and the cell casing.

[0019] As an alternative to a bimetal, the connecting conductor can also have rolled plates in the contact areas between the connecting conductor and the cell terminal or the connecting conductor and the second pole.

[0020] The above object is also achieved according to the invention by a high-voltage storage device with a cell assembly, as described above, and an outer housing. The cells are housed in the outer housing, as is a carrier board in the area of ​​the poles. The connecting conductors are attached to the carrier board, particularly at stops. The additional fixation of the carrier board in the outer housing minimizes any displacement, thereby significantly reducing the risk of a thermal event. Further advantages and features of the invention will become apparent from the following description and the drawings to which reference is made. In the drawings:

[0021] Figure 1 is a schematic representation of a cell assembly according to the invention in plan view;

[0022] Figure 2a is a schematic representation of a connecting conductor as used in Figure 1;

[0023] Figure 2b is a schematic representation of a corresponding further component;

[0024] Figure 3a is a schematic representation of another embodiment of the connecting conductor;

[0025] Figure 3b is a schematic representation of a corresponding further component;

[0026] Figure 4 is a schematic representation of a cell contacting system of a cell of the cell assembly of Figure 1;

[0027] Figure 5 is a schematic representation of the carrier board shown in Figure 3;

[0028] Figure 6 is a schematic representation of the connecting conductor according to a second embodiment;

[0029] Figure 7 is a schematic representation of the connecting conductor according to a third embodiment; and

[0030] Figure 8 is a schematic representation of a high-voltage storage device according to the invention.

[0031] Figure 1 shows a cell assembly 10 of a high-voltage storage device 12. The cell assembly 10 comprises several cells 14 and connecting conductors 16 (in this example, four connecting conductors 16), which are part of a cell contact system 18. The cell contact system 18 is described in more detail below.

[0032] A top connecting conductor 16 connects eight cells 14 to each other to form a parallel connection 20, the second and third from the top connect ten cells 14 each and the bottom five cells 14, whereby the parallel connections 20 are also connected in series.

[0033] The cells 14 are preferably round cells, in particular round cells, each corresponding to 4.2 volt batteries. Thus, conventional cells 14 can be used in the high-voltage storage unit 12, thereby reducing costs.

[0034] The cells 14 are arranged in rows, with rows of adjacent cells 14 being offset from one another. This allows electrically insulating seals 22 to be positioned between the respective rows of cells 14.

[0035] Furthermore, the individual cells 14 can protrude into spaces between adjacent round cells of the neighboring rows in order to build compactly in the vertical direction, with reference to Figure 1.

[0036] Figure 2a shows a connecting conductor 16 in detail. The connecting conductor 16 has a wave-shaped section 24 from which freely projecting contact arms 26 extend in opposite directions. The contact arms 26 are part of the cell contact system 18 and serve to establish an electrical connection between individual cells 14.

[0037] The wave-shaped section 24 is a wave-like structure of the connecting conductor 16, which is located in the plate plane of the plate-shaped connecting conductor 16.

[0038] The contact arms 26 are divided into contacts for first poles 28 and second poles 30, with the first pole 28 typically being the positive pole and the second pole 30 being the negative pole. The contact area of ​​the first pole 28 is formed by a rounded circuit board 32, while the contact area of ​​the second pole 30 is formed by a free end 36 of the connecting conductor 16 provided with an indentation 34. The indentation 34 then surrounds the first pole 30 of the corresponding round cell at a distance.

[0039] In the embodiment shown in Figure 2a, the connecting conductor 16 also has a plurality of recesses 38. The recesses 38 are configured to receive a projection 40 or a fixing part 42, whereby the connecting conductor 16 can be attached to another component. The other component is shown in Figure 2b. The recesses 38 thus form a stop 60 for the connecting conductor 16.

[0040] Alternatively, the connecting conductor 16 can also have a projection 44, as can be seen in Figure 3a, which can engage in a recess 46 of the further component, as shown in Figure 3b, in order to fasten the connecting conductor 16.

[0041] Consequently, the connection between the connecting conductor 16 and the further component is established by a positive connection.

[0042] Thus, the connection is preferably a reversible connection so that individual cells 14 can be replaced if necessary.

[0043] Another alternative, not shown, provides that the connecting conductor 16 is riveted to the other component.

[0044] Figure 4 shows the cell contact system 18 of a cell 14 of the cell assembly 10. The cell 14 comprises a cell terminal 50 formed by an extension 48, which forms the first pole 28.

[0045] The cell terminal 50 extends through an opening 52 in a cell housing 54, which forms the second pole 30. An electrically insulating cell seal 56 is arranged between the cell terminal 50 and the edge of the opening 52 of the cell housing 54.

[0046] The cell contact system 18 also comprises a connecting conductor 16, in particular a contact arm of the connecting conductor 16, which in Figure 4 abuts the cell terminal 50. An overload protection device 58, in particular a fuse, is mounted adjacent to the contact point between the connecting conductor 16 and the cell terminal 50, i.e., the rounded circuit board 32.

[0047] The overload protection device 58 serves to disconnect a connection between the cell terminal 50 and the connecting conductor 16 in contact with the other cells 14 when a predetermined reference temperature is exceeded. The overload protection device 58 thus serves to prevent the propagation of a thermal event. As can be seen in Figure 2a, the overload protection device 58 can be formed by a constriction on the connecting conductor 16. Alternatively, the overload protection device 58 can also have two webs, as can be seen, for example, in Figure 7.

[0048] The overload protection device 58 shown in Figure 7 has, in particular, a wave-like structure when viewed from the side, wherein the overload protection device 58 protrudes from the plane of the connecting conductor 16 and forms a resilient section acting in the direction between the stops 60.

[0049] In addition to the cell contact system 18 and the overload protection device 58, a stop 60 is also shown in Figures 4 and 7. The stop 60 attaches the connecting conductor 16 to another component, in this case, the other component being a carrier board 62. One embodiment of the carrier board 62 is shown in Figure 5. The connecting conductor 16 is integrated into the carrier board 62 and thus attached to it.

[0050] Alternatively or additionally, the connecting element 16 can be fastened to a cover 64 of the cell assembly 10 via an additional stop 60 (see Figure 8).

[0051] Figure 6 shows a second embodiment of the connecting conductor 16. According to this embodiment, the connecting conductor 16 is multi-layered and comprises two interconnected plates 66. In principle, the connecting conductor 16 can also consist of more than two plates 66, 67, but the connecting conductor 16 is preferably a bimetal.

[0052] The first plate 66 is made of an electrically conductive material and is designed to establish electrical contact between the individual cells 14. Accordingly, the first plate 66 corresponds to the previously described connecting conductor 16.

[0053] The second plate 67, on the other hand, is designed to stiffen the connecting conductor 16 and is preferably made of a material with a low coefficient of expansion. Preferably, the material has a coefficient of expansion of 0 K. -1 or a negative

[0054] Expansion coefficients. Thus, the second plate 67 counteracts the expansion of the connecting conductor 16, so that the overall expansion is minimized. The material for the second plate 67 can be, for example, an iron-nickel alloy.

[0055] A third embodiment of the connecting conductor 16 can be seen in Figure 7. The connecting conductor 16 shown here preferably consists of a sheet metal having at least one embossed portion 68. The embossed portion 68 serves to stiffen the connecting conductor 16 and thus minimize its expansion.

[0056] The connecting conductors 16 shown in Figure 7 have an overload protection device 58 both at the connection point to the rounded circuit board 32 and at the connection point to the recess 34. The overload protection device 58 can be seen in both a single-stage and a double-stage version.

[0057] Figure 8 shows the high-voltage storage device 12, which comprises a cell assembly 10 and an outer housing 70. The individual cells 14 of the cell assembly 10 are housed in the outer housing 70, which can be closed by the cover 64. In addition to the cells 14, the carrier board 62 is also housed in the outer housing 70, with the carrier board 62 being arranged in the region of the poles 28, 30 of the cells 14. The connecting conductor 16 is attached to the carrier board 62 via stops 60.

Claims

Patent claims 1. Cell assembly (10) of a high-voltage storage device (12), with a plurality of cells (14), each cell (14) having a cell terminal (50) of a first pole (28) formed by an extension (48) and a second pole (30) forming a cell housing (54), and connecting conductors (16) which electrically connect the cell terminals (50) and / or second poles (30) to one another, the connecting conductors (16) being fastened to the cell terminals (50) and / or second poles (30) to be connected and being fastened to a further component at least at additional stops (60).

2. Cell assembly (10) according to claim 1, characterized in that the further component to which the connecting conductors (16) are fastened is a carrier board (62) and / or a cover (64) of the cells (14).

3. Cell assembly (10) according to claim 1 or 2, characterized in that stops (60) are formed by a recess (38), wherein the recess (38) is designed to receive a projection (40) of the further component or a fixing part (42) which is locked to the further component.

4. Cell assembly (10) according to one of the preceding claims, characterized in that stops (60) are formed by a projection (44), in particular a pin, on the connecting conductor (16), wherein the projection (44) is designed to engage in a recess (46) in the further component, and / or that connecting conductors (16) are riveted to the further component.

5. Cell assembly (10) according to one of the preceding claims, characterized in that an overload protection device (58), in particular a fuse, is provided on the connecting conductor (16), which can separate a connection between the connecting conductor (16) and the cell contacting system if a previously determined reference temperature is exceeded.

6. Cell assembly (10) according to one of the preceding claims, characterized in that the connecting conductors (16) each consist of a sheet metal, wherein the sheet metal has at least one embossing (68).

7. Cell assembly (10) according to one of the preceding claims, characterized in that stops (60) are located between adjacent cell terminals (50) and / or second poles (30) to which the connecting conductor (16) is attached and / or at free ends (36) of the connecting conductor (16).

8. Cell assembly (10) according to one of the preceding claims, characterized in that the connecting conductors (16) have a wave-shaped section (24) from which freely projecting contact arms (26) protrude, which are fastened to the cell terminals (50) and / or second poles (30), and in that stops (60) are provided on contact arms (26).

9. Cell assembly (10) according to one of the preceding claims, characterized in that the connecting conductors (16) are designed in multiple layers and comprise interconnected plates (66, 67), wherein a first plate (66) consists of an electrically conductive material, and wherein a material of a second plate (67) has an expansion coefficient of 0 K' 1 or has a negative expansion coefficient.

10. High-voltage storage device (12), with a cell assembly (10) according to one of the preceding claims and an outer housing (70) in which the cells (14) are accommodated, as well as a carrier board (62) in the region of the poles (28, 30) to which the connecting conductors (16) are fastened, in particular at stops (60).

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