阅读说明：本技术 用于机动车的能量存储器装置、机动车及制造方法 (Energy storage device for a motor vehicle, motor vehicle and method for producing the same ) 是由 A·达尔巴迪 J·玛丽 J·希尔丁格 F·埃克施泰因 于 2020-03-05 设计创作，主要内容包括：本文公开的技术涉及一种用于机动车(100)的能量存储器装置(100)。所述能量存储器装置(100)包括多个用于电化学储能的圆形电池单体(120)和存储器壳体(110),在该存储器壳体中设置有所述多个圆形电池单体(120)。所述圆形电池单体(120)在它们的安装位置中基本上平行于车辆横向轴线(Y)延伸。所述圆形电池单体(120)在存储器壳体(110)内沿车辆竖直轴线(Z)方向分多层(L1、L2、L3、L4)设置,层(L1、L2、L3、L4)的数量沿车辆纵向轴线(X)方向变化。此外,本文公开的技术还涉及一种机动车以及一种用于制造能量存储器装置(100)的方法。(The technology disclosed herein relates to an energy storage device (100) for a motor vehicle (100). The energy storage device (100) comprises a plurality of round battery cells (120) for electrochemical energy storage and a storage housing (110) in which the plurality of round battery cells (120) is arranged. The round battery cells (120) extend substantially parallel to a vehicle transverse axis (Y) in their installation position. The round battery cells (120) are arranged in multiple layers (L1, L2, L3, L4) in the direction of the vehicle vertical axis (Z) within the reservoir housing (110), the number of layers (L1, L2, L3, L4) varying in the direction of the vehicle longitudinal axis (X). Furthermore, the technology disclosed herein also relates to a motor vehicle and a method for manufacturing an energy storage device (100).)

1. Energy storage device (100) for a motor vehicle (100), comprising:

-a plurality of circular battery cells (120) for electrochemical energy storage; and

-a reservoir housing (110) in which the plurality of circular battery cells (120) are arranged;

wherein the round battery cells (120) extend substantially parallel to a vehicle transverse axis (Y) in their mounted position, the round battery cells (120) being arranged in a plurality of layers (L1, L2, L3, L4) in a vehicle vertical axis (Z) direction within the reservoir housing (110); the number of layers (L1, L2, L3, L4) varies in the direction of the vehicle longitudinal axis (X).

2. Energy storage device (100) according to claim 1, wherein the length to diameter ratio of the circular battery cells (120) has a value between 5 and 30, preferably between 7 and 15 and particularly preferably between 9 and 11.

3. Energy storage device (100) according to claim 1 or 2, wherein the round cells (120) each comprise at least one coated electrode semi-finished product which does not have a mechanical separating edge perpendicular to the longitudinal axis of the round cell (120) which is produced by a separating process step after coating of the electrode semi-finished product.

4. Energy storage device (100) according to any one of the preceding claims, wherein the circular battery cells (120) each comprise at least one coated electrode semi-finished product having a rectangular cross section, the length of the long side of the electrode semi-finished product being substantially equal to the total width of a carrier layer web coated with an anode material or a cathode material to form the electrode semi-finished product.

5. The energy storage device (100) as claimed in any one of the preceding claims, wherein the storage housing (110) has an upper side which, in its housing contour (KG), is adapted to a lower-side interior contour (KI) of a passenger compartment (150) of the motor vehicle (100), the overall height (HL1, HL2) of the plurality of layers (L1, L2, L3, L4) varying in the following manner for the adaptation to the housing contour (KG): the directly adjacent circular battery cells (120) of one layer (L1) in a first region of the layer (L1) are spaced further apart from each other in the vehicle longitudinal axis (X) direction than the directly adjacent circular battery cells (120) in a second region (B2) of the same layer (L1).

6. The energy storage device (100) as claimed in any of the preceding claims, wherein at least one lowermost layer (L1) extends from a forefoot region (FV) of the storage housing (110) adjoining the forefoot space up to a rear seat region (SH) of the storage housing (110) adjoining the rear seat.

7. The energy storage device (100) as claimed in any of the preceding claims, wherein fewer layers (L1, L2, L3) are provided in at least one of the foot regions (FF, FB) of the storage housing (110) adjoining the front or rear foot spaces (FV, FH) than in the seat regions (SV, SH) of the storage housing (110) adjoining the front and/or rear seats.

8. Energy storage device (100) according to any one of the preceding claims, wherein at least the circular battery cells (120) of the lowermost layer (L1) are oriented such that all ends of the circular battery cells (120) arranged on the side of the lowermost layer (L1) have the same polarity.

9. The energy storage device (100) according to any one of the preceding claims, wherein a layer of a plurality of circular battery cells (120) is connected to each other by an adhesive applied on the plurality of circular battery cells (120).

10. Energy storage device (100) according to any one of the preceding claims, wherein at least one at least partially undulated positioning element is provided on the housing bottom, in which a plurality of round battery cells (120) are accommodated to form a layer (L1, L2, L3).

11. Energy storage device (100) according to one of the preceding claims, wherein a cooling element (140) for cooling the round battery cells (120) is provided between at least two layers, preferably the cooling element is at least partially wave-shaped.

12. Energy storage device (100) according to any one of the preceding claims, wherein the round battery cell (122) has at least one air vent on each of the two ends, respectively.

13. Motor vehicle comprising an energy storage device (100) according to any of the preceding claims.

14. Method for manufacturing an electrochemical cell, in particular a round cell (120), comprising the steps of: after coating at least one carrier layer web forming the electrode semi-finished product with a cathode material or an anode material, the electrode semi-finished product is wound into a battery cell, and the coated carrier layer web is not subjected to a further separation process step in the longitudinal direction of the carrier layer web.

15. Method for producing an energy storage device (100), comprising the following steps:

-manufacturing a plurality of battery cells according to the method of claim 14; and is

-providing a battery cell into an energy storage device (100) according to any of claims 1 to 12.

Technical Field

The technology disclosed herein relates to an energy storage device for a motor vehicle and a motor vehicle having such an energy storage device.

Background

Such energy storage devices are used, for example, in battery-operated motor vehicles. High-voltage accumulators are known, for example, from the prior art, which have a plurality of round cells, prismatic cells or pouch cells. The circular battery cell can be manufactured at low cost. Based on the form factor and the large number of round cells, it is complicated to integrate round cells into an energy storage device. The manufacturing of prismatic cells or pouch cells is also relatively complex.

Disclosure of Invention

A preferred task of the technology disclosed herein is to reduce or eliminate at least one of the drawbacks of the known solutions or to propose alternative solutions. Among other things, a preferred task of the technology disclosed herein is to provide an energy storage device that is improved in at least one of the following factors: manufacturing time, manufacturing cost, manufacturing complexity, utilization of installation space, sustainability, and/or component reliability. Other preferred tasks may result from advantageous effects of the techniques disclosed herein. The object is achieved by the solution of the independent claims. The dependent claims constitute preferred embodiments.

An electrical energy accumulator device is a device for storing electrical energy, in particular for driving at least one (traction) drive motor. The energy storage device comprises at least one electrochemical cell for storing electrical energy. The energy storage means may be a high-voltage storage or a high-voltage battery, for example.

The energy storage device comprises at least one storage housing. The energy storage device can be a battery pack, and the like. The reservoir housing is expediently designed to be gas-tight, so that gases which may escape from the battery cells are collected. Advantageously, the housing can be used for fire protection, contact protection, intrusion protection and/or for protection against moisture and dust.

The reservoir housing can be made at least partially of metal, in particular of aluminum, an aluminum alloy, steel or a steel alloy. At least one or more of the following components can be accommodated in the at least one accumulator housing of the energy accumulator device: a storage battery cell, a component of power electronics, a contactor for interrupting the power supply to the motor vehicle, a cooling element, an electrical conductor, a controller. The energy storage device can have, in particular, elements to be cooled, in particular, battery cells and/or components of the power electronics of the energy storage device. It is convenient to pre-assemble these components prior to installation of the assembly in the vehicle.

An electrical energy storage device comprises a plurality of circular cells for electrochemical storage of energy. The round cells are typically housed in a cylindrical cell housing. If the active material of the round battery cell expands due to operation, the case is subjected to tensile stress in the circumferential region. The relatively thin housing cross section can thus advantageously compensate for the forces generated by the expansion. Preferably, the cell housing is made of steel or a steel alloy.

The circular battery cell may have at least one air outlet on each of both end portions, respectively. The vent is used to allow generated gases to escape from the cell housing. But only one air vent may be provided for each circular battery cell. Advantageously, at least one air outlet opening per round cell is provided in the installation position for exhausting air towards the outer door sill.

The ratio of the length to the diameter of the round battery cell preferably has a value of between 5 and 30, preferably between 7 and 15, and particularly preferably between 9 and 11. The ratio of length to diameter is the quotient of the cell housing length of a round cell as the numerator and the cell housing diameter of a round cell as the denominator. In a preferred embodiment, the round battery cell has, for example, an (outer) diameter of about 45 to 55 mm. Furthermore advantageously, the round battery cell can have a length of 360mm to 1100mm, preferably about 450mm to 600mm, and particularly preferably about 520mm to 570 mm.

According to the technology disclosed herein, it can be provided that the round battery cell is produced from a coated semi-finished electrode. Suitably, the cathode material or the anode material is applied to the carrier layer or carrier layer web, respectively, of the respective semi-finished electrode. The cathode material can be applied to a cathode support layer (e.g., aluminum) and the anode material can be applied to an anode support layer (e.g., copper), for example, by a coating.

According to the prior art, the carrier layer web is coated with a cathode material or an anode material, a plurality of coating regions being provided distributed over the entire width (for example 1000mm and greater) of the carrier layer web, in which the cathode material or the anode material, respectively, is applied. For a common round cell, such a coating area may be, for example, about 65mm wide. After coating with anode material or cathode material, the carrier layer web is reduced to the desired round cell size (e.g. 65mm) by a number of separate process steps. For this purpose, the carrier layer web is separated in the longitudinal direction of the carrier layer web in each case in the uncoated region arranged between the coated regions. The impurities (usually metal particles) that occur during the separation may enter the coating and the separation process step is very time consuming. Both of which are undesirable in practice.

According to the technology disclosed herein, it can be provided that the round cell comprises at least one coated electrode blank which has no mechanical separating edge perpendicular and/or parallel to the longitudinal axis of the round cell, which is produced by a separating process step after the coating of the electrode blank.

According to the technology disclosed herein, it can be provided that the round battery cells each comprise at least one coated electrode semi-finished product having a rectangular cross section, the length of the long side of the electrode semi-finished product being substantially equal to or greater than the total width of a carrier layer web which is coated with an anode material or a cathode material to form the electrode semi-finished product, so that the electrode semi-finished product can be wound after coating and without further separating process steps in the longitudinal direction of the carrier layer web.

In particular, the technology disclosed herein also includes a method for manufacturing an electrochemical cell, in particular a round cell, comprising the steps of: the electrode semi-finished product is wound into a cell after coating at least one carrier layer web forming the electrode semi-finished product with a cathode material or an anode material, and the carrier layer web after coating is not subjected to a further separation process step in the longitudinal direction of the carrier layer web.

In other words, the at least one electrode semi-finished product is wound after coating and without further separating process steps in the longitudinal direction of the web. Preferably, the semifinished product forming the cathode, anode or separator is wound after coating without a separate process. Furthermore, the technology disclosed herein also includes a method for manufacturing the energy storage device disclosed herein, the method comprising the steps of:

-manufacturing a plurality of battery cells, in particular round battery cells, as described above; and is

-providing a battery cell into an energy storage device as disclosed herein.

According to the technology disclosed herein, the circular battery cells extend substantially parallel (i.e., parallel with possible deviations that are insignificant to the functional effect) to the vehicle transverse axis Y in their mounted position. The vehicle transverse axis is an axis which extends perpendicular to the vehicle longitudinal axis X and horizontally in the normal position of the motor vehicle.

The round battery cells are arranged in multiple layers in the storage shell along the direction of the vertical axis Z of the vehicle. The vehicle vertical axis is an axis which extends perpendicular to the vehicle longitudinal axis X and vertically in the normal position of the motor vehicle. A layer of round battery cells here refers to a plurality of round battery cells which are mounted in the same plane of the reservoir housing and have substantially the same distance from the bottom of the reservoir housing. Advantageously, the number of layers varies along the vehicle longitudinal axis X.

According to the technology disclosed herein, the reservoir housing can have an upper side which in its outer housing contour is adapted to the lower inner contour of the motor vehicle passenger compartment, the overall height of the multiple layers in the mounted position for adaptation to the housing contour varying in the vehicle longitudinal axis direction in the following manner: the circular battery cells of one layer which are directly adjacent in a first region of the layer are spaced further apart from one another in the direction of the vehicle longitudinal axis in the installation position than the circular battery cells of the same layer which are directly adjacent in a second region of the same layer, so that the extent to which a further circular battery cell of another layer sinks into a first intermediate region formed by the circular battery cells of the first region is advantageously greater than the extent to which a further circular battery cell of the same construction of the other layer sinks into a second intermediate region formed by the circular battery cells of the second region. The total height of the plurality of layers is measured from the bottom of the memory housing to the upper end of the uppermost layer at the corresponding location in the memory housing. The interior contour of the passenger compartment is a contour that defines a passenger compartment interior space accessible to a vehicle user. In particular, the housing contour can be adapted to the inner contour in such a way that a suitably constant gap, preferably less than 15cm or less than 10cm or less than 5cm, is provided between the upper side of the storage housing and the inner contour of the passenger compartment.

According to the technology disclosed herein, at least one lowermost layer of the plurality of layers in the mounted position of the energy storage device extends in the vehicle longitudinal axis direction from a front foot region of the storage housing which in the mounted position adjoins the motor vehicle front foot space up to a seat region of the storage housing which adjoins the motor vehicle rear seat.

According to the techniques disclosed herein, fewer layers may be provided in at least one of the foot regions of the reservoir housing adjacent to the front or rear foot spaces of the motor vehicle than in the seat regions of the reservoir housing adjacent to the front and/or rear seats of the motor vehicle (e.g., single seat or rear row seats). It can thus be provided advantageously that, for example, only the lowermost round battery cells are arranged in the storage housing in the front and/or rear foot region, whereas a plurality of layers are arranged one above the other in the front and/or rear seat region. This has the following advantages: in particular, the installation space below the front seat or below the rear seat can be used more efficiently, in order to increase the electrical storage capacity of the motor vehicle.

Furthermore, it can be advantageously provided that at least the lowermost circular battery cell is arranged in such a way that all the ends of the circular battery cells arranged on the lowermost side have the same polarity. Preferably, the two circular battery cells arranged one above the other are oriented in such a way that all ends of the circular battery cells in the two layers which are arranged on the first side each have the same polarity, wherein the polarity of the end of the first of the two layers on the first side is opposite to the polarity of the end of the second of the two layers. Such an embodiment advantageously has a low internal resistance.

Alternatively, it can be provided that all electrical terminals of the round cells of all layers are arranged on one side. This embodiment is particularly space-saving.

Particularly preferably, the cell electrical terminals of the round cells are electrically insulated from the cell housing. Thus, the individual cell housings are potential-free.

In a preferred embodiment, it can be provided that a plurality of round battery cells of a layer are connected to one another by means of an adhesive applied to the plurality of round battery cells of the same layer. The adhesive can expediently be applied only after the individual round cells of a layer have been positioned relative to one another, for example after the round cells have been placed into the reservoir housing. It is therefore advantageous that the individual round cells of a layer can be fixed relative to one another in a cost-effective and space-saving manner. As the binder, for example, polyurethane, polyamide or polyethylene can be used.

In a preferred embodiment, at least one at least partially undulated positioning element is arranged on the housing base, in which a plurality of round battery cells are accommodated to form a layer, in particular the lowermost layer. Suitably, the positioning element extends perpendicular to the longitudinal axis of the circular battery cell. Furthermore, the positioning element can advantageously be designed in the form of a strip.

According to the technology disclosed herein, a cooling element for cooling the round battery cells can be arranged between at least two layers, which cooling element is preferably at least partially corrugated in a cross section perpendicular to the transverse vehicle axis Y. In one embodiment, the cooling element can be connected to a cooling circuit of a motor vehicle.

The technology disclosed herein also relates to a motor vehicle that includes the energy storage device disclosed herein.

In other words, the technology disclosed herein relates to a new cell specification that advantageously shortens cell production cycle time by up to 5 times and reduces energy inactive components in the cell structure. This embodiment can reduce the cell costs and is advantageous with regard to cell integration, as a result of which the available installation space in the storage device or in the motor vehicle can be better utilized. Furthermore, the memory can be advantageously adapted to the topology of the passenger compartment and disadvantageous installation spaces can also be filled efficiently with energy units (battery cells). The manufacturing cost of the round battery cell is relatively low. Even in comparison with known round cells having other shapes, further manufacturing steps, in particular the cutting of the semifinished product, can be saved. This additionally reduces the possibility of failure due to impurities that may enter the battery cell during its manufacture. The circular battery cells disclosed herein have a relatively light cell housing that can be manufactured using relatively little material. By using a steel housing, aluminum can advantageously be dispensed with in the production of the cell housing, which has a positive effect on production costs and sustainability. The cell housing can be manufactured with relatively short weld seams. Compared to other cell sizes, the circular cells disclosed herein are less susceptible to run-induced swelling and possible manufacturing tolerances are insignificant, which may simplify module integration. Furthermore, the technology disclosed herein is based on the basic idea of a cylindrical cell specification with a height/length to diameter ratio of 6 to 25. Advantageously, the number of inactive components can be reduced. It is also advantageous that the electrodes can be coated with a higher material density and thus achieve a higher energy density. Overall, the already good energy density of the round cells at the cell level can also be increased further at the energy storage level by better utilization of space. In particular, long current collectors can be avoided to a large extent, thereby reducing line losses.

Drawings

The technology disclosed herein will now be explained with reference to the accompanying drawings. The attached drawings are as follows:

fig. 1 shows a schematic partial view of a longitudinal section through a motor vehicle according to the prior art;

FIG. 2 illustrates a schematic partial view of a longitudinal cross-sectional view of a motor vehicle in accordance with the techniques disclosed herein;

FIG. 3 illustrates a schematic partial view of a longitudinal cross-sectional view of a motor vehicle in accordance with another embodiment of the technology disclosed herein;

FIG. 4 shows a schematic cross-sectional view along the line IV-IV of FIG. 5;

FIG. 5 shows a schematic cross-sectional view along the line V-V of FIG. 4;

FIG. 6 shows a schematic cross-sectional view along the line VI-VI of FIG. 4;

fig. 7 shows a schematic cross-sectional view along the line VII-VII of fig. 4;

FIG. 8 shows a schematic cross-sectional view of another embodiment; and

fig. 9 shows a schematic cross-sectional view of another embodiment.

Detailed Description

Fig. 1 shows a schematic partial view of a longitudinal section through a motor vehicle according to the prior art. The high-voltage battery 1 shown here comprises a plurality of prismatic battery cells 3. The battery cells 3 are arranged vertically. In this case, the battery cells cannot be arranged in the rear foot region, since there is not a sufficient installation space height for the battery cells. Further, it is not possible to provide two layers of battery cells stacked under the front seat or under the rear seat. The contour of the housing 3 of the high-voltage battery 1 depends on the configuration of the prismatic battery cells 3.

Fig. 2 shows a schematic partial view of a longitudinal cross-section of a motor vehicle according to the technology disclosed herein. The cells of the energy storage device 100 are designed here as round cells 120, which are accommodated in an organized manner in layers in the storage housing 110. The round battery cells 120 are arranged here substantially parallel to the vehicle transverse axis Y. The lowermost round battery cell 120 extends in this case counter to the direction of the vehicle longitudinal axis X from the front foot region FV of the accumulator housing 110 as far as the rear seat region SH of the accumulator housing 110. The rear seat region SH is provided here below the rear seats. The number of layers varies in the direction of the vehicle longitudinal axis X in order to thus make optimum use of the installation space. The height of the individual round battery cells 120 or layers in the direction of the vertical axis Z of the vehicle results here from the maximum outer diameter of the round battery cells 120. Since the maximum outer diameter of the circular battery cell 120 is relatively small compared to the known prismatic battery cells, the existing installation space in the vehicle vertical axis Z direction can be better utilized. It is furthermore advantageous if the shell contour KG is adapted to the inner contour KI of the passenger compartment 150 (see also fig. 5). In order to make better use of the installation space, the directly adjacent round battery cells 120 in the rear seat region SH or the first region B1 are arranged further apart from one another in a direction parallel to the vehicle longitudinal axis X than the directly adjacent round battery cells 120 in the front seat region SV or the second region B2. By this measure, the directly adjacent second layer of round battery cells 120 in the first region B1 can be sunk deeper into the middle region of the first or lower layer, so that a total of three layers can be integrated in the first region. Without this measure, only two layers can be provided in the installation space.

Fig. 3 illustrates a schematic partial view of a longitudinal cross-sectional view of a motor vehicle in accordance with another embodiment of the technology disclosed herein. In the following description of the alternative embodiment shown in fig. 3, the same reference numerals are used to indicate features which are identical and/or at least comparable in their implementation and/or mode of action to those of the first embodiment shown in fig. 2. Unless they are explained in detail again, their embodiments and/or modes of action correspond to the embodiments and/or modes of action of the features already described above. The embodiment according to fig. 3 differs from the previous embodiments in that the inner contour KI and the housing contour KG of the energy storage device 100 are changed in the region of the rear seats. Overall, the energy storage device 100 has more installation space in the rear seat region along the vehicle vertical axis Z. Therefore, more layers are provided than in the embodiment according to fig. 2, wherein the uppermost three layers have circular battery cells 120 spaced further apart in the vehicle longitudinal axis X direction in order to better accommodate the overall height.

Fig. 5 shows a schematic cross-sectional view along the line V-V of fig. 4, which shows the energy storage device 100 of fig. 2 and the interior profile KI of the motor vehicle. The remaining components of the motor vehicle are omitted for simplicity. In fig. 5, a first intermediate region ZB is shown, which is formed by the directly adjacent round cells 120 of the lowermost layer L1.

Fig. 4 shows a schematic cross-sectional view along the line IV-IV of fig. 5. The plurality of circular battery cells 120 are arranged parallel to the vehicle lateral axis Y. The circular battery cell 120 has a length to diameter ratio of about 10. The cooling element 140 is arranged here perpendicular to the round battery cells 120 and parallel to the vehicle longitudinal direction X. The cooling element 140 is configured in the form of a strip. The width of the cooling element 140 is many times smaller than the length of the circular battery cell 120. The cooling element 140 may be configured to be substantially undulated in a cross-section perpendicular to the vehicle transverse axis Y. The cooling element 140 is omitted in other views and cross-sections for simplicity. The adhesive that can be applied between the two cooling elements 140 is not shown here and in the other figures. An adhesive is suitably used to connect the circular battery cells 120 of one layer L1, L2, L3, L4 to each other. The wave-shaped positioning elements, which in one embodiment position the lowermost layers relative to one another on the bottom of the housing, are also not shown here. In the embodiment shown here, the electrical terminals of the circular battery cells 120 are disposed on the outer edge of the lowermost layer L1. The round battery cells 120 preferably have air vents only at the outer ends toward the outer edge or toward the outer longitudinal member (not shown here) of the motor vehicle. In the embodiment shown here, the two lowermost layers L1 are arranged in this order in the vehicle lateral axis Y direction. The two lowermost layers L1 are arranged parallel to each other. It is likewise conceivable to provide only one lowermost layer L1 or three lowermost layers L1 in the memory housing. It is likewise conceivable to provide, instead of two circular cell stacks, only one circular cell stack with correspondingly longer circular cells 120 or three circular cell stacks with correspondingly shorter circular cells 120.

Fig. 6 shows a schematic cross-sectional view along the line VI-VI in fig. 4. Two circular cell stacks are provided in the reservoir housing 110. In this cross-sectional view, each stack comprises a plurality of layers L1, L2, L3, L4, which layers together have a total height HL 2. The overall height HL2 is substantially equal to the height of the interior of the reservoir housing 110, which is defined here by the bottom and by the housing contour KG on the upper side of the reservoir housing 110. In this case, the layers L1 and L3 are arranged in the foreground, the full diameter of which can be seen here. The layers L2 and L4 are shown here in the background and sink into the middle region (see fig. 5).

Fig. 7 shows a schematic cross-sectional view along the line VII-VII of fig. 4, again with the layers L1 and L3 arranged in the foreground and the layers L2 and L4 arranged in the background. In contrast to the cross section of fig. 6, the layers L1 and L3 are here recessed deeper into the middle zone ZB, so that the resulting overall height HL1 is significantly smaller than the overall height HL2 of fig. 6. Even though the enlarged middle area reduces the number of circular cells 120 per layer, this technique allows integration of multiple layers at a lower overall height, thereby increasing the electrical storage capacity as a whole.

Fig. 8 shows the arrangement of the poles of a circular battery cell in the embodiment according to fig. 5. As already mentioned, the two cell electrical terminals of the circular battery cell 120 are respectively provided on the outer end portions. The outer end portion refers to an end portion close to the outer side member of the vehicle body. Advantageously, an air outlet is also provided at each of these ends. Such an embodiment can be constructed particularly compactly, since the gap between two circular cell stacks can be smaller.

Fig. 9 shows a schematic cross-sectional view of another embodiment. In contrast to the embodiment according to fig. 8, the electrical terminals of the battery cells are arranged on both sides of the round battery cell 120. Such an embodiment may advantageously have a lower line loss. The circular cells 120 of a layer, e.g. all circular cells 120 of the lowermost layer L1, have the same polarity (here denoted by the symbol +) on one side, e.g. the outside, of the layer. On the other, inner side of the same layer, all circular cells 120 of the same layer have the same and opposite polarity to the first side. In the directly adjacent layers, for example layer L2, the ends of one side in turn each have an electrical connection of the same polarity. But the polarity is different from the polarity of the immediately adjacent layer, such as the lowermost layer L1. A layer structure of circular battery cells 120 thus configured and having such an orientation enables a particularly cost-effective and energy-saving interconnection of the circular battery cells 120.

The foregoing description of the invention is for the purpose of illustration only and is not intended to be limiting of the invention. Within the scope of the present invention, various improvements and modifications may be made without departing from the scope of the present invention and its technical equivalents. Even though energy storage devices with circular cells are shown herein, the techniques disclosed herein may be applied to other cell geometries that suitably have the cross-sectional length ratios disclosed herein.