BATTERY SYSTEM AND VEHICLE INCLUDING THE BATTERY SYSTEM

Abstract

A battery system includes: a battery housing; a plurality of battery cells arranged in a plurality of battery cell groups within the battery housing; and a separation sheet. Each battery cell group has a venting side with a venting exit configured to vent a venting stream from the battery cells to exit the battery cell group, and the separation sheet is at venting sides of the battery cell groups. The separation sheet forms separate venting chambers for each of the battery cell groups and is configured to guide the venting stream leaving the venting exits away from the battery cell groups through openings in the separation sheet.

Claims

1. A battery system comprising: a battery housing; a plurality of battery cells arranged in a plurality of battery cell groups within the battery housing, each battery cell group has a venting side with a venting exit configured to vent a venting stream from the battery cells to exit the battery cell group; and a separation sheet at the venting sides of the battery cell groups, the separation sheet forming separate venting chambers for each of the battery cell groups, the separation sheet being configured to guide the venting stream leaving the venting exits away from the battery cell groups through openings in the separation sheet.

2. The battery system of claim 1, further comprising a cover element facing the venting side of the battery cell groups, wherein the separation sheet is arranged between the cover element and the venting side of the battery cell groups, wherein a venting channel is arranged between the separation sheet and the cover element, the venting channel fluidly connecting a system exit of the battery housing with the venting chambers via the openings in the separation sheet.

3. The battery system of claim 2, wherein the cover element is a bottom cover.

4. The battery system of claim 3, wherein the bottom cover is part of an underbody of the battery housing.

5. The battery system of claim 1, wherein the battery cell groups are supported by the separation sheet.

6. The battery system of claim 5, wherein the separation sheet is a structural member of the battery system.

7. The battery system of claim 1, wherein the separation sheet comprises guiding surfaces configured to guide the venting stream towards the opening.

8. The battery system of claim 7, wherein a first one of the guiding surfaces is at a first end of the venting chamber, and the opening is at a second end of the venting chamber opposite the first end such that the venting stream is guided from the venting exit along the venting side towards the opening.

9. The battery system of claim 1, wherein each of the battery cell groups is a cell stack, and each of the cell stacks comprising battery cells electrically connected with one another.

10. The battery system of claim 1, wherein the battery cell groups are arranged in multiple rows, wherein for each row of the battery cell groups, the separation sheet is arranged at the venting side of the battery cell groups, the separation sheet forming separate venting chambers for each of the battery cell groups in the respective row for guiding the venting stream leaving the venting exits away from the battery cell groups through openings in the separation sheet.

11. An electric vehicle comprising the battery system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Aspects and features of the present disclosure will become apparent to those of ordinary skill in the art by describing, in detail, embodiments thereof with reference to the attached drawings, in which:

[0030] FIG. 1 is a schematic perspective view of a battery system according to an embodiment,

[0031] FIG. 2 shows a separation sheet of the battery system shown in FIG. 1 in a schematic perspective view,

[0032] FIG. 3 is a partial cut-away view of a separation sheet taken along the line II-II of FIG. 2 with a battery cell group, and

[0033] FIG. 4 is a sectional view taken along the line III-III of FIG. 3.

DETAILED DESCRIPTION

[0034] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Aspects and features of the present disclosure, and implementation methods thereof, will be described with reference to the accompanying drawings. In the drawings, like reference numerals denote like elements, and redundant descriptions thereof may be omitted. The present disclosure, however, may be embodied in various different forms and should not be construed as being limited to only the embodiments illustrated herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art.

[0035] Accordingly, processes, elements, and techniques that are not considered necessary to those having ordinary skill in the art for a complete understanding of the aspects and features of the present disclosure may not be described. In the drawings, the relative sizes of elements, layers, and regions may be exaggerated for clarity. For example, in the drawings, the size or thickness of each element may be arbitrarily shown for illustrative purposes, and thus the embodiments of the present disclosure should not be construed as being limited thereto.

[0036] As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.” In the following description of embodiments of the present disclosure, the terms of a singular form may include plural forms unless the context clearly indicates otherwise.

[0037] It will be understood that although the terms “first,” “second,” etc. are used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be named a second element and, similarly, a second element may be named a first element, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions, such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0038] As used herein, the term “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Further, if the term “substantially” is used in combination with a feature that could be expressed using a numeric value, the term “substantially” denotes a range of +/−5% of the value centered on the value.

[0039] It will be further understood that the terms “have,” “include,” “comprise,” “having,” “including,” “comprising,” or variations thereof specify a property, a region, a fixed number, a step, a process, an element, a component, and a combination thereof but do not exclude other properties, regions, fixed numbers, steps, processes, elements, components, and combinations thereof.

[0040] It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected, or coupled to the other element or layer or one or more intervening elements or layers may also be present. When an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. For example, when a first element is described as being “coupled” or “connected” to a second element, the first element may be directly coupled or connected to the second element or the first element may be indirectly coupled or connected to the second element via one or more intervening elements.

[0041] Herein, the terms “top” and “bottom” are defined according to the z-axis. For example, the top cover is positioned at the upper part of the z-axis, and the bottom cover is positioned at the lower part thereof.

[0042] In the following description of embodiments of the present disclosure, the terms of a singular form may include plural forms unless the context clearly indicates otherwise.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification, and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

[0044] FIG. 1 shows an embodiment of a battery system 10 for an electric vehicle according to an embodiment of the present disclosure. The battery system 10 includes a plurality of battery cells 12 and a bottom cover 20, which is part of a battery housing. In this embodiment, the battery cells 12 are cylindrical cells, but they could have a different shape. The battery cells 12 are arranged in battery cell groups 13, and neighboring battery cell groups 13 are spaced apart spatially from one another along multiple rows 15. The battery cells 12 of each battery cell group 13 are electrically interconnected with one another and, thus, form a cell stack via an electrical connector 17 shown in, for example, FIG. 4. Neighboring battery cell groups 13 in the same row 15 may be electrically interconnected with one another, and the neighboring rows 15 of battery cell groups 13 may also be electrically interconnected with one another so that all of the battery cells 12 form a battery module with the battery cell groups 13 and/or rows 15 as submodules.

[0045] Each battery cell group 13 and, therefore, the entirety of the battery cells 12, has a venting side 14 at a bottom side. Each battery cell group has at least one venting exit 16 through which a venting stream V including venting products may exit the battery cell group 13 in case of, for example, a thermal runaway (see, e.g., FIGS. 3 and 4). Thus, the battery cells 12 are arranged to vent the venting stream downwardly towards the bottom cover 20.

[0046] The battery system 10 also includes separations sheets 30, and each row 15 of battery cell groups 13 is supported on one separation sheet 30. Each separation sheet 30 is arranged at the venting sides 14 of the corresponding battery cell group 13. In the first two rows 15 shown in FIG. 1, some of the battery cell groups 13 are not shown to allow for a view of the underlying separation sheets 30. The separation sheets 30 act as structural members carrying (or supporting) their respective battery cell groups 13. In addition, the battery system 10 includes struts 22 extending in parallel with the separation sheets 30. The struts 22 provide stability to the whole (or overall) battery system 10. The separation sheets 30 may be supported by the struts 22. The separation sheets 30 may also provide stability to the whole (or overall) battery system 10.

[0047] The separation sheet 30 forms separate venting chambers 36 such that there is one venting chamber 36 provided for each battery cell group 13 in each row 15. These venting chambers 16 guide the venting stream V leaving the venting exits 16 away from the battery cell groups 13 through openings 32 in the separation sheet 30, as will be explained in more detail below. FIG. 2 shows one of the separation sheets 30 with the equidistantly arranged openings 32. The separation sheet 30 has the shape of a shallow trough or channel with a depression extending along the x-axis. For example, the separation sheet 30 includes two longitudinal profile rails 33 and a downwardly tapering channel bottom 34 with sloping side walls 35. The sloping side walls 35 are sloped with respect to the y-axis as shown in FIG. 2.

[0048] When the battery cell groups 13 are arranged on the separation sheet 30, the channel bottom 34, together with the sloping side walls 35, forms the venting side 14 with a carrier element 18 and the venting chambers 36. The battery cell groups 13 are arranged on the separation sheet 30 such that one battery cell group 13 is placed between every two neighboring openings 32, as can be seen in, for example, FIGS. 3 and 4. The venting chamber 36 is delimited upwardly by the venting side 14 (or the carrier element 18) to form a first side and downwardly by the separation sheet 30 to form a second side opposite the first side. The venting chamber 36 is further delimited to the sides (e.g., to the lateral sides) by sidewall members 39. The separation sheet 30 may be formed via deep drawing a sheet, such as a metal sheet. By such a drawing method, the venting chamber 36 including the sidewall members 39 may be drawn. The openings 32 may be formed at the same time (e.g., concurrently). The sidewall members 39 can be seen in, for example, FIG. 4.

[0049] In a first step of a thermal runaway event, a venting stream V including hot venting gasses and products leaves (e.g., is emitted by or from) the battery cell group 13, as shown in FIGS. 3 and 4, at the venting side 14 through the venting exit 16. In some embodiments, a venting valve may be provided at the venting exit 16. In a second step of the thermal runaway event, the venting gas expands into the venting chamber 36 such that the pressure of the venting gas and, due to the thermal mass of the venting chamber 36, the temperature of the venting gas is reduced. Also, the venting stream V is guided down the sloping side walls 35 of the separation sheet 30 to the center of the channel bottom 34 and, therefore, to the center of the venting chamber 36. In other words, the sloping side walls 35 act as first guiding surfaces. The sloping side walls 35 are shown in FIG. 3. The sidewall members 39 may act as second guiding surfaces. The right-side sidewall member 39a guides the venting stream V to the left towards the left-side sidewall member 39b, and the left-side sidewall member 39b guides the venting stream V through the opening 32. As can be seen in, for example, FIG. 4, the sidewall member 39 of one venting chamber 36 act not only as a guiding surface for the venting stream of this venting chamber 36 but also as a guiding surface for the venting stream of a neighboring cell chamber because the sidewall members 39 form dividing walls separating two neighboring cell chambers.

[0050] In a third step of a thermal runaway event, the venting stream V is channelled away from the battery cell group 13 through the opening 32 into a venting channel 40, which is arranged between the separation sheet 30 and the bottom cover 20 (see, e.g., FIG. 4). The venting stream V may join a main venting stream V.sub.m flowing along the venting channel 40 when it enters the venting channel 40. The main venting stream V.sub.m may include the venting streams of other battery cell groups. The venting channel 40 connects (e.g., fluidly connects or flows to) a system exit 38 of the battery housing, which is shown schematically in FIG. 1, with the venting chambers 36 via the openings 32. In a fourth step of the thermal runaway event, a venting valve provided at the system exit 38 opens at a certain (e.g., a reference) pressure to release the main venting stream V.sub.m to the environment of the battery system 10.

[0051] Due to the venting chambers 36, a venting stream V leaving one of the battery cell groups 13 does not directly enter the venting channel 40 but instead first passes through the venting chamber 36. The venting chamber 36, due to its thermal mass, reduces the temperature of the venting stream before the venting stream V enters the joint/main venting channel 40. The venting chamber 36, thus, acts as a buffer space for the venting stream V where the venting stream V is pre-cooled before entering the venting channel 40. Further, the battery cell groups 13 are protected by the separation sheet 30 and its dedicated venting chambers 36 and side walls (e.g., guiding surfaces) 35, 39, which lead the venting stream V away from the battery cells 12 towards the opening 32. The venting products are, therefore, not deposited onto the battery cells. The separation sheet 30, thus, also cats as a baffle.

[0052] The disclosed venting geometry provides sufficient cool-down of the venting products before leaving the respective venting chamber so that the risk of damaging other cells via heat propagation is reduced. Also, the venting chambers shield the respective battery cell group from a venting stream leaving another (e.g., an adjacent) venting chamber because the venting stream cannot easily enter other venting chambers. Further, the venting products exiting the battery system towards the environment are at a relatively lower temperature.

SOME REFERENCE SIGNS

[0053] 10 battery system [0054] 12 battery cells [0055] 13 battery cell groups [0056] 14 venting side [0057] 15 rows of battery cell groups [0058] 16 venting exit [0059] 17 connecting means [0060] 18 carrier element [0061] 20 bottom cover [0062] 22 struts [0063] 30 separation sheet [0064] 32 openings in the separation sheet [0065] 33 profile rails [0066] 34 channel bottom [0067] 35 sloping side walls [0068] 36 venting chamber [0069] 38 system exit [0070] 40 main venting channel [0071] V venting stream [0072] V.sub.m main venting stream