Energy storage device for storing electrical energy for a motor vehicle

Abstract

The invention relates to an energy storage device for storing electrical energy, preferably for a motor vehicle that is at least partially electrically powered. The invention further relates to a motor vehicle comprising such an energy storage device. The energy storage device (1) for storing electrical energy comprises a first battery cell stack module (3). The first battery cell stack module (3) includes several storage cells (4) arranged side by side for storing electrical energy, as well as a cooling device (5) through which a coolant flows, which is arranged laterally, preferably on the bottom, with respect to the first battery cell stack module (3). The cooling device (5) comprises several cooling plates (6) arranged side by side, wherein at most one, preferably only one, of the storage cells (4) of the first battery cell stack module (3) is arranged on each of the several cooling plates (6).By means of this energy storage device (1) the risk of further storage cells (4) of the first battery cell stack module (3) being damaged by overheating of a storage cell (4) can be reduced.

Description

[0001] The invention relates to an energy storage device for storing electrical energy, preferably for an at least partially electrically powered motor vehicle. Furthermore, the invention relates to a motor vehicle having such an energy storage device.

[0002] In modern HV batteries for electrically powered vehicles, numerous storage cells, such as lithium-ion battery cells, are typically placed as close as possible to one another, sometimes stacked in multiple layers, and combined into so-called battery packs. To achieve optimal performance, the storage cells should each be operated within a specific temperature range, depending on the type of storage cell. For this purpose, it is known from the prior art to provide the storage cells collectively per layer – usually from one side, e.g., from below – with active cooling, e.g., using a cooling plate.

[0003] A key goal in battery pack development is typically to maximize the energy density of the battery pack, allowing as much energy as possible to be stored while consuming as little volume as possible. The individual battery cells are typically connected both electrically and thermally.

[0004] Damage mechanisms (e.g., accidents, vibrations, excessive external thermal stress, etc.) can cause a short circuit in the electrical contacts within a storage cell. This can generate large amounts of heat, which can lead to overheating and even ignition and burning of the storage cell. The resulting thermal energy is quickly dissipated into the environment and, via existing thermal (i.e., heat-conducting) connections, to neighboring storage cells, which can also cause them to overheat and ignite.

[0005] For this reason, thermal insulation layers are sometimes used between the individual storage cells to reduce the risk of a chain reaction-like combustion of the storage cells. Within the scope of the invention, it was discovered that a large amount of heat can also be transferred to neighboring storage cells via the shared cooling plate of a level, which cannot be prevented by the insulation between the individual storage cells.

[0006] The invention is therefore based on the object of providing an improved energy storage device for storing electrical energy that, as far as possible, also avoids the disadvantages of the previous solution. In particular, it is an object of the invention to provide an energy storage device for storing electrical energy that can increase safety in the event of damage to the energy storage device.

[0007] According to a general aspect of the present disclosure, an energy storage device for storing electrical energy is provided, preferably for an at least partially electrically powered motor vehicle. The energy storage device comprises a battery cell stack module, comprising a plurality of storage cells (battery cells) arranged next to one another for storing electrical energy. The battery cell stack module is thus a module made up of storage cells arranged next to one another in a stack. The storage cells can be designed, for example, as prismatic storage cells. The battery cell stack module is referred to below as the first battery cell stack module to better distinguish it from other optionally present battery cell stack modules (described below), and does not imply any order or prioritization.

[0008] The energy storage device further comprises a cooling device through which a coolant can flow, which is arranged laterally, preferably at the bottom, with respect to the first battery cell stack module. The coolant can be a liquid coolant, e.g., a water-glycol mixture. The cooling device comprises a plurality of cooling plates arranged side by side. At most one of the storage cells of the first battery cell stack module is arranged on each of the plurality of cooling plates. Preferably, only one or exactly one of the storage cells of the first battery cell stack module is arranged on each of the plurality of cooling plates; however, it is also possible for no storage cell to be arranged on one or more cooling plates.

[0009] Instead of a large common cooling plate for cooling the first battery cell stack module, several (small) cooling plates are provided for the individual storage cells. Because the storage cells of a battery cell stack module are not arranged on a common cooling plate, but each on its own cooling plate, the (waste) heat of a storage cell transferred to one of the individual cooling plates is not transferred, or at least only to a limited extent, to the other cooling plates and thus to the other storage cells. This means that if a storage cell overheats and possibly even burns down due to a defect, e.g., triggered by an accident, the resulting heat can be dissipated via the cooling plate of this storage cell without excessively heating neighboring storage cells.The risk that neighboring storage cells also overheat and burn down, and in the worst case scenario that the entire battery cell stack module burns down, can be significantly reduced or even completely prevented.

[0010] Preferably, each storage cell of the first battery cell stack module is cooled by only one of the cooling plates and / or is thermally coupled to only one cooling plate. A thermally conductive material, e.g., a thermally conductive paste, can be arranged between the storage cells and the respective cooling plate. Furthermore, a width of the cooling plates can correspond to or substantially correspond to a width of the storage cells.

[0011] According to one embodiment, the energy storage device further comprises thermal insulation arranged between adjacent cooling plates of the cooling device. The thermal decoupling of the cooling plates from one another can thereby be improved, so that in the event of overheating of one storage cell, the risk of overheating spreading to other storage cells can be further reduced. The thermal insulation can comprise or be made of a material that has a thermal conductivity of 1 W / (m*K) or less, preferably 0.2 W / (m*K) or less.

[0012] According to a further aspect, the storage cells can each have an insulating layer on their side surfaces facing the adjacent storage cells of the first battery cell stack module, i.e., the side surfaces that are perpendicular to the stacking direction of the first battery cell stack module. For thermal insulation of adjacent cooling plates, this insulating layer extends beyond the storage cell to an intermediate region between the adjacent cooling plates. In other words, the insulating layer covers not only the side surface of a storage cell, but also a side surface of a cooling plate (or of two adjacent cooling plates) arranged between two adjacent cooling plates. The thermal decoupling of adjacent storage cells and adjacent cooling plates is thereby improved.

[0013] Furthermore, according to a further embodiment, a gap, preferably an air gap, can be arranged between adjacent cooling plates. A gap, e.g., an air gap, can further reduce heat transfer between adjacent cooling plates. However, it is also possible for no gap to be provided and only thermal insulation to be provided between adjacent cooling plates.

[0014] According to a further aspect, the energy storage device can further comprise a second battery cell stack module. The second battery cell stack module comprises a plurality of storage cells arranged side by side for storing electrical energy. The second battery cell stack module can be designed analogously to the first battery cell stack module. The stacking direction of the first and second battery cell stack modules is the same. The second battery cell stack module is arranged on the cooling device, offset perpendicular to the stacking direction from the first battery cell stack module.

[0015] At most one, preferably only one or exactly one, of the storage cells of the second battery cell stack module is arranged on each of the multiple cooling plates. This means that a maximum of one storage cell of the first battery cell stack module and a maximum of one storage cell of the second battery cell stack module are arranged on each cooling plate. The number of battery cell stack modules is not limited to two. More than two battery cell stack modules can also be arranged one behind the other, as long as a maximum of one storage cell of each battery cell stack module is arranged on each cooling plate.

[0016] Accordingly, the energy storage device can alternatively further comprise a plurality of further battery cell stack modules. The plurality of further battery cell stack modules each comprise storage cells arranged next to one another for storing electrical energy, wherein the plurality of further battery cell stack modules are each arranged behind the first battery cell stack module and one behind the other on the cooling device. The plurality of further battery cell stack modules can be designed analogously to the first battery cell stack module. The stacking direction of the first and the plurality of further battery cell stack modules is the same. At most one, preferably only one, of the storage cells is arranged on each of the plurality of cooling plates of each of the plurality of battery cell stack modules.

[0017] In this way, a straightforward and cost-effective design, in particular simple and cost-effective assembly, can be enabled without sacrificing the advantages of the invention. In particular, unwanted heat transfer between the individual storage cells of a battery cell stack module is further advantageously reduced.

[0018] In an advantageous development, the first battery cell stack module and the second battery cell stack module or the plurality of further battery cell stack modules can be arranged at a distance from one another (at a distance from one another) on the cooling device. For example, a gap, preferably a gap filled with air and / or an insulating material, can be arranged between the first battery cell stack module and the second battery cell stack module or between the plurality of further battery cell stack modules. The insulating material can comprise or be made of a material that has a thermal conductivity of 1 W / (m*K) or less, preferably 0.2 W / (m*K) or less. In this way, direct heat transfer, in particular heat conduction, through direct contact between the storage cells of the individual battery cell storage modules can be at least reduced.

[0019] According to a further aspect, the cooling plates of the cooling device are arranged in a plane and / or parallel to one another. Furthermore, the cooling plates can be connected to a common coolant supply and / or a common coolant discharge and / or a common coolant circuit.

[0020] According to a further advantageous embodiment, the storage cells have contacts for electrical contacting, wherein the contacts are arranged on the surfaces of the storage cells opposite the cooling plates. The electrical contacts can be designed according to a conventional design variant known from the prior art. In this way, the individual storage cells can be interconnected via cell connectors without the cooling plates restricting the space required for this purpose.

[0021] In a further advantageous embodiment, at least one, preferably exactly one, cooling line for conducting the coolant is arranged in each cooling plate. The cooling lines can be designed, for example, as through-holes through which the coolant can flow. The through-holes can then be connected, for example, to coolant lines outside the cooling plates. Alternatively, coolant lines can also be routed through the cooling plates. The cooling lines enable particularly uniform temperature control of the cooling plates.

[0022] According to a further general aspect of the present disclosure, a motor vehicle comprising an energy storage device as described above is provided. The motor vehicle is particularly preferably a commercial vehicle, for example a truck, a tractor unit, a construction machine, or a bus.

[0023] In other words, the features described in this document in connection with the energy storage device per se should also be disclosed and claimable in connection with the motor vehicle. The motor vehicle can, for example, be a purely electric or at least partially electrically driven commercial vehicle. In this case, a commercial vehicle can generally be understood to mean a vehicle which, due to its design and equipment, is specifically designed for the transport of persons, the transport of goods or the towing of trailers. Overall, this advantageously makes it possible to provide a motor vehicle whose energy storage device can be operated with improved safety, in particular improved safety with regard to thermal runaway of a storage cell.

[0024] The above-described preferred embodiments and features of the invention can be combined with one another as desired. Further details and advantages of the invention are described below with reference to the accompanying drawings. They show: Fig. 1 a schematic illustration of an exemplary energy storage device from the prior art; Fig. 2 is a schematic illustration of an energy storage device having a first battery cell stack module according to an embodiment; Fig. 3 is a schematic illustration of an energy storage device with a first battery cell stack module according to another embodiment; Fig. 4 is a schematic illustration of an energy storage device having a first and a second battery cell stack module according to another embodiment; and Fig. 5 a schematic illustration of a motor vehicle comprising an energy storage device according to another embodiment of the invention.

[0025] The embodiments shown in the figures correspond at least partially, so that similar or identical parts are provided with the same reference numerals and for their explanation reference is also made to the description of the other embodiments or figures in order to avoid repetition.

[0026] Fig. Figure 1 initially shows a schematic illustration of an energy storage device known from the prior art. The energy storage device shown consists, for example, of three prismatic storage cells 4 arranged in a stack on a common cooling plate 6. Using contacts 14 for electrical contact, the storage cells 4 can be electrically connected to one another, for example, by means of busbars (not shown).

[0027] In the case shown, the contacts 14 are arranged on the surfaces 15 of the storage cells 4 opposite the cooling plate 6.

[0028] The cooling plate 6 is traversed by cooling lines 16 through which a coolant, for example, liquid or gaseous, can flow. When the storage cells 4 become warm, the thermal connection between the storage cells 4 and the cooling plate 6 transfers heat to the coolant, which then transfers the heat to a heat sink (not shown), for example, via coolant lines (not shown).

[0029] The individual storage cells 4 are each provided with thermal insulation 7 on their mutually facing side surfaces 9. If a storage cell 4 is damaged, e.g. due to an accident or other strong mechanical shocks, this can lead to a short circuit within the storage cell, which can then burn down in a highly exothermic reaction due to the heat generated. The thermal insulation 7 is intended, among other things, to prevent the heat generated from spreading to the neighboring storage cells 4, since these could also overheat due to this heat and thus burn down without themselves being mechanically damaged. The thermal insulation 7 can therefore at least partially prevent thermal energy from passing directly from the overheated storage cell 4 to a neighboring storage cell 4.

[0030] However, a large portion of the released thermal energy is transferred to the cooling plate 6, which in turn can become considerably hot. If the coolant flowing through the cooling lines 16 cannot dissipate the heat quickly enough, the cooling plate can become so hot that the neighboring storage cells 4 are no longer cooled by the cooling plate 6, but instead are heated. A chain reaction-like burning of the storage cells 4 can result.

[0031] Accordingly, Fig. Figure 2 shows a schematic illustration of an energy storage device 1 for storing electrical energy according to one embodiment of the invention. It shows a first battery cell stack module 3, which comprises a plurality of storage cells 4 arranged side by side in a stack for storing electrical energy.

[0032] Examples include the Fig. 2 shows three prismatic memory cells 4, but there could also be more or fewer memory cells 4. In the Fig. 2, the stacking direction is indicated by the arrow S. The storage cells 4 each have contacts 14 on their upper side for electrical contacting, by means of which the storage cells 4 of the first battery cell stack module 3 can be electrically connected, e.g., by means of cell connectors (not shown here).

[0033] Furthermore, a cooling device 5 through which a coolant can flow is shown, which is arranged laterally, here on the bottom side, with respect to the first battery cell stack module 3.

[0034] The cooling device 5 comprises a plurality of cooling plates 6 arranged next to one another in a plane that is parallel to the stacking direction S, wherein at most one of the storage cells 4 of the first battery cell stack module 3 is arranged on each of the plurality of cooling plates 6. Preferably, exactly one storage cell 4 is arranged on each cooling plate 6, but it is also possible for no storage cell 4 of the first battery cell stack module 3 to be arranged on one or more cooling plates 6. The storage cells 4 of the first battery cell storage module 3 are each cooled by only one of the cooling plates 6 and / or are each thermally coupled to only one cooling plate 6. A gap, preferably an air gap, can be arranged between adjacent cooling plates 6. This means that the individual cooling plates 6 do not touch one another.

[0035] The cooling plates 6 can be made of metal, heat-conducting plastic or heat-conducting ceramic, for example.

[0036] Preferably, cooling lines 16 for guiding the coolant are arranged and / or integrated in each cooling plate 6. The cooling lines 16 can, for example, be designed as through-holes that can be connected to an external (not shown) coolant circuit. Alternatively, coolant lines of a coolant circuit can also be guided through the cooling lines 16. Preferably, at least one, preferably exactly one, cooling line 16 is arranged in each cooling plate 6. The number of cooling lines 16 in the individual cooling plates 6 can be identical or at least partially different from one another. In the Fig. In the example shown in Figure 2, two cooling lines 16 are arranged in each cooling plate 6. The flow direction of the coolant in the Fig. The two cooling lines 16 shown in Figure 2 can run in the same direction or in opposite directions. This ensures that the cooling plates 6 are evenly tempered. Furthermore, the most flexible connection to an external coolant circuit is possible.

[0037] Due to the separated, thermally decoupled cooling plates 6, a chain reaction-like burning of the battery cell stack module 3 due to a malfunction of an individual storage cell 4 can advantageously be prevented, or the risk thereof can at least be significantly reduced. Should one of the storage cells 4 overheat and possibly even burn down, e.g. due to a short circuit, primarily only the cooling plate 6 with which the overheated storage cell 4 is in direct contact heats up. The neighboring cooling plates 6 are also heated, e.g. due to thermal radiation, however, the heating of the neighboring cooling plates 6 is significantly lower due to the separation of the individual cooling plates 6 than it would be with a common cooling plate (as in the Fig. 1). The risk that neighboring storage cells 4 could also overheat and thus burn down is significantly reduced by the separate cooling plates 6. Furthermore, individual temperature control of the individual storage cells 4 can optionally be carried out, e.g., by controlling the flow of the coolant through the cooling lines 16. This allows the storage cells 4 to be operated within an individually optimal temperature range, which increases the service life of the storage cells 4 and the operational reliability of the energy storage device 1.

[0038] In order to further increase the individual temperature controllability of the individual storage cells 4, the storage cells 4 can each have thermal insulation 7, here for example designed as an insulating layer, on their side surfaces 9 facing the adjacent storage cells 4 of the first battery cell stack module 3. The insulating layer 7 between the individual storage cells 4 ensures that temperature changes of a storage cell 4 do not affect, or at least have a lesser effect, on adjacent storage cells 4. A thermal insulator can be understood, for example, as a material that has a thermal conductivity of 1 W / (m*K) or less, preferably 0.2 W / (m*K) or less. The insulating layer 7 can extend beyond the storage cells 4 to an intermediate region 12 between the adjacent cooling plates 6, as shown in Fig. 2. In other words, the large-area lateral insulating layers between the storage cells 4 are also used for insulation between the individual cooling plates 6. In this way, the effect of a temperature change of one cooling plate 6 on an adjacent cooling plate 6 can be reduced. It would also be possible for an independent thermal insulation to be arranged between adjacent cooling plates 6 of the cooling device 5.

[0039] In the Fig. 3 shows a further schematic illustration of an energy storage device 1 with a first battery cell stack module 3 according to a further embodiment. It is understood that the Fig. 3 with the techniques and features described with reference to the Fig. 2 are combinable, individually or in any combination.

[0040] The energy storage device 1 of the Fig. 3 differs from that of the Fig. 2 in the number of storage cells 4 of the first battery cell stack module 4. In the Fig. Figure 3 shows four prismatic memory cells 4 as examples. The memory cells 4 could also be designed as pouch cells, for example.

[0041] The Fig. Figure 4 shows a schematic illustration of an energy storage device 1 according to a further embodiment of the invention. It is understood that the energy storage device 1 described with reference to Fig. 4 with the techniques and features described with reference to the Fig. 2 or Fig. 3 are combinable, individually or in any combination.

[0042] The energy storage device 1 comprises, in addition to a first battery cell stack module 3 and a cooling device 5, an additional second battery cell stack module 13. Like the first battery cell stack module 3, the second battery cell stack module 13 comprises a plurality of adjacently arranged storage cells 4 for storing electrical energy, wherein the second battery cell stack module 13 is arranged behind the first battery cell stack module 3 on the cooling device 5. The term "behind" here refers to a spatial direction that is perpendicular to the stacking direction S.

[0043] The two battery cell stack modules 3, 13 are arranged on the cooling device 5 such that at most one of the storage cells 4 of the second battery cell stack module 13 is arranged on each of the plurality of cooling plates 6. This means that a maximum of one storage cell 4 of each battery cell stack module 3, 13 is arranged on a respective cooling plate 6. A single cooling plate 6 therefore always cools only a single storage cell 4 or only the storage cells 4 located in its extension. The illustrated structure enables a simple and cost-effective construction, as well as a simple and cost-effective assembly of an energy storage device 1, while simultaneously retaining the previously described advantages of separate and / or thermally decoupled cooling plates 6.

[0044] The first battery cell stack module 3 and the second battery cell stack module 13 can preferably be arranged at a distance from one another on the cooling device 5. Furthermore, a gap, for example an air gap, can preferably be arranged between the first battery cell stack module 3 and the second battery cell stack module 13, i.e. the storage cells 4, which are each arranged on a common cooling plate 6, do not touch one another. Additionally or alternatively, the gap between the first battery cell stack module 3 and the second battery cell stack module 13 can be filled with an insulating material. The second battery cell stack module 13 can be designed analogously to the first battery cell stack module 3. The number of battery cell stack modules is not limited to two.Accordingly, three, four, or more battery cell stack modules can be arranged one behind the other on the cooling device 5, as long as at most one storage cell 4 from each of the battery cell stack modules is arranged on each cooling plate 6. The term "one behind the other" again refers to a spatial direction that is perpendicular to the stacking direction S.

[0045] Fig. Figure 5 shows a schematic representation of a motor vehicle 2 with an energy storage device 1 according to an embodiment of the invention. It is understood that the Fig. 5 with the techniques and features described with reference to the Fig.2 to 4, can be combined, individually or in any combination. The motor vehicle 2 can - as shown by way of example - be designed as a commercial vehicle (e.g., a tractor unit or a truck with a body). However, the motor vehicle 2 can also be a passenger car. Preferably, the motor vehicle 2 is an at least partially or purely electrically powered motor vehicle 2. The energy storage device 1 can be arranged on a longitudinal outer side of the motor vehicle 2 or at another location.

[0046] Although the invention has been described with reference to specific embodiments, it will be apparent to one skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. Consequently, the invention is not intended to be limited to the disclosed embodiments, but is intended to include all embodiments falling within the scope of the appended claims. In particular, the invention also claims protection for the subject matter and features of the dependent claims, independent of the referenced claims. List of reference symbols 1 energy storage device 2 motor vehicles 3 First battery cell stack module 4 memory cells 5 Cooling device 6 Cooling plate 7 Thermal insulation, e.g. insulating layer 9 Side surface 12 Intermediate area 13 Second battery cell stack module 14 Electrical contact 15 cooling plates opposite surface 16 Cooling line

Claims

[1] Energy storage device (1) for storing electrical energy, preferably for an at least partially electrically powered motor vehicle (2), comprising: a first battery cell stack module (3) comprising a plurality of storage cells (4) arranged next to one another for storing electrical energy; a cooling device (5) through which a coolant can flow, which is arranged laterally, preferably on the bottom, with respect to the first battery cell stack module (3); wherein the cooling device (5) comprises a plurality of cooling plates (6) arranged next to one another, wherein at most one, preferably only one, of the storage cells (4) of the first battery cell stack module (3) is arranged on each of the plurality of cooling plates (6). [2] Energy storage device (1) according to claim 1, wherein each storage cell (4) of the first battery cell stack module (3) is cooled by only one of the cooling plates (6) and / or is thermally coupled to only one cooling plate (6). [3] Energy storage device (1) according to claim 1 or 2, further comprising a thermal insulation (7) arranged between adjacent cooling plates (6) of the cooling device (5). [4] Energy storage device (1) according to one of the preceding claims, wherein the storage cells (4) each have an insulating layer (7) on their side surfaces (9) facing the adjacent storage cells (4) of the first battery cell stack module (3), which insulating layer extends beyond the storage cell (4) to an intermediate region (12) between the adjacent cooling plates (6) for the thermal insulation of adjacent cooling plates (6). [5] Energy storage device (1) according to one of the preceding claims, wherein a gap, preferably an air gap, is arranged between adjacent cooling plates (6). [6] Energy storage device (1) according to one of the preceding claims, further comprising a second battery cell stack module (13) comprising a plurality of storage cells (4) arranged side by side for storing electrical energy, wherein the second battery cell stack module (13) is arranged behind the first battery cell stack module (3) on the cooling device (5), wherein at most one, preferably only one, of the storage cells (4) of the second battery cell stack module (13) is arranged on each of the plurality of cooling plates (6); or further comprising a plurality of further battery cell stack modules, each comprising a plurality of storage cells (4) arranged next to one another for storing electrical energy, wherein the plurality of further battery cell stack modules are each arranged behind the first battery cell stack module (3) and one behind the other on the cooling device (5), wherein at most one, preferably only one, of the storage cells is arranged on each of the plurality of cooling plates (6) of each of the plurality of battery cell stack modules. [7] Energy storage device (1) according to claim 6, a) wherein the first battery cell stack module (3) and the second battery cell stack module (13) or the plurality of further battery cell stack modules are arranged at a distance from one another on the cooling device (5), and / or b) wherein a gap, preferably a gap filled with air and / or an insulating material, is arranged between the first battery cell stack module (3) and the second battery cell stack module (13) or between the plurality of further battery cell stack modules. [8] Energy storage device (1) according to one of the preceding claims, wherein the cooling plates (6) are arranged in one plane and / or parallel to one another. [9] Energy storage device (1) according to one of the preceding claims, wherein the storage cells (4) have contacts (14) for electrical contacting, wherein the contacts (14) are arranged on the surfaces (15) of the storage cells (4) opposite the cooling plates (6). [10] Energy storage device (1) according to one of the preceding claims, wherein at least one, preferably exactly one, cooling line (16) for guiding the coolant is arranged in each cooling plate (6). [11] Energy storage device (1) according to one of the preceding claims, wherein the storage cells (4) are prismatic storage cells. [12] Motor vehicle (2), preferably commercial vehicle, with an energy storage device (1) according to one of the preceding claims.

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