DE102020110012A1 - Electric energy storage device and motor vehicle - Google Patents

Abstract

The technology disclosed here relates to an electrical energy storage device 5 with a plurality of energy storage cells 10, the energy storage cells 10 being interconnected along system current paths S and exclusively parallel current paths P, which have a lower current carrying capacity than the system current paths S, are formed between the system current paths S.

Description

The technology disclosed here relates to an electrical energy storage device and a motor vehicle with such an energy storage device.

Energy storage devices can have a plurality of energy storage cells, each of which is designed to store electrical energy. As an alternative to large energy storage cells, which can take over the energy supply of a motor vehicle alone or at least in a group of only a few energy storage cells, it can often be useful to use numerous energy storage cells, which can be smaller in comparison and thus enable better utilization of installation space . Typically, parallel and series connections are used in order to increase the storage capacity and / or to increase the output voltage. In known designs, system power and parallel power typically share the same electrical path. Parallel currents arise in particular due to slightly different electrical internal resistances of energy storage cells connected in parallel. Parallel currents compensate for this in an advantageous manner. System currents are typically those currents that are led to the outside and flow there through a consumer.

It is a preferred object of the technology disclosed here to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, it is a preferred object of the technology disclosed here to provide an electrical energy storage device with increased resistance to malfunctions. Further preferred objects can result from the advantageous effects of the technology disclosed here. The objects are achieved by the subject matter of the independent claims. The dependent claims represent preferred configurations.

The technology disclosed here relates to an electrical energy storage device which has a plurality of energy storage cells. Some of the energy storage cells are electrically connected in series along a first system current path and some of the energy storage cells are electrically connected in series along a second system current path. Each system current path has a current carrying capacity. Each system current path is formed by means of a plurality of connection points, each connection point connecting a pole of an energy storage cell to a pole of a further energy storage cell in the system current path. Only one or more parallel current paths are formed between the system current paths. Each parallel current path runs between a connection point of a system flow path and a connection point of another system flow path. Each parallel current path expediently has a lower current carrying capacity than every system current path.

Such an electrical energy storage device can ensure that malfunctions in individual energy storage cells, which in known designs can lead to particularly high parallel currents, do not damage energy storage cells in other system current paths. A malfunction, for example in the form of a short circuit in an energy storage cell, therefore remains limited to this energy storage cell.

In principle, in a modification, only one parallel current path can have a lower current carrying capacity than one, some or all of the system current path (s), or some parallel current paths can have a lower current carrying capacity than one, some or all of the system current path (s).

In system current paths, those currents typically flow which are routed to the outside of the energy storage device and flow there through loads, for example through an electric motor for driving a motor vehicle. Parallel current paths are current paths in which currents typically flow due to slightly different internal resistances between energy storage cells or between system current paths, such parallel currents typically being relatively low. However, should an energy storage cell be short-circuited or have a thermal fault, such parallel currents can assume very large values and therefore become dangerous. This is precisely what is prevented by the technology disclosed here, namely due to the lower current carrying capacity.

A thermal failure is usually a failure in which an exothermic chemical reaction occurs. Such an error can also be a thermal event ("Thermal Runaway"). The fault can in particular be an event that causes a non-operational and self-reinforcing heat production in the individual cells. Under certain circumstances, it could use propagation. Such a fault can be caused, for example, by an internal short circuit in a single cell or by a source of fire.

With the exception of the parallel current paths, system current paths are separate from one another. An exception to this can be common connection elements at the ends of the system current paths. These are then not considered part of the Considered system current paths, they typically connect connections of energy storage cells of the same polarity. Typically, each system current path only connects energy storage cells that are not connected by any other system current path or that do not belong to any other system current path. In particular, a positive pole of an energy storage cell can be connected to a negative pole of the next energy storage cell in the system current path, or vice versa, along a system current path. This corresponds to a series connection of the energy storage cells. The voltages of the energy storage cells thus typically add up along the system current path, so that a higher output voltage is achieved.

A connection is to be understood here in particular as an electrical connection.

The parallel current paths can, in particular, connect to one another connection points which are arranged on the same side or on longitudinal ends of energy storage cells lying next to one another. Typically, a connection point connects exactly one pole of an energy storage cell with exactly one pole of a further energy storage cell.

In particular, it can be provided that all system current paths have the same current carrying capacity. It can also be provided that all parallel current paths have the same current carrying capacity. In particular in the case of the parallel current paths, there may also be deviations, for example on or adjacent to interruptions.

The connection points can be formed by suitable connection means such as plates, wires or other electrical conductors. Their design typically defines the current carrying capacity of the system current paths. Each connection point typically connects two poles of energy storage cells which are connected in series along the respective system current path, in particular poles of different polarity.

A current carrying capacity is typically the maximum current that can flow along a current path, in particular without the current flow being interrupted. The current-carrying capacity of a system current path can in particular be defined by the connection points or their design. The connection points of a connection path can in particular have an identical current-carrying capacity, which then represents the current-carrying capacity of the system current path. The connection points can, however, also have different current-carrying capacities, in which case, for example, the lowest current-carrying capacity among the connecting means can define the current-carrying capacity of the system current path.

The electrical energy storage device is in particular a device for storing electrical energy, in particular in order to drive at least one electrical (traction) drive machine. The energy storage device comprises a plurality of energy storage cells, which are each designed as individual cells, and typically a plurality of such individual cells, which form the electrochemical energy storage cells. As a rule, a large number of individual cells are provided. For example, the energy storage device can be a high-voltage storage device or a high-voltage battery.

The energy storage device typically comprises at least one storage housing. The storage housing is expediently an enclosure that surrounds at least the high-voltage components of the energy storage device. The storage housing is expediently designed to be gas-tight, so that any gases that may escape from the storage cells are intercepted. The housing can advantageously be used for fire protection, contact protection, intrusion protection and / or for protection against moisture and dust.

The storage housing can be made at least partially from a metal. In particular, it can be made 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 storage housing of the energy storage device: energy storage cells, components of the power electronics, contactor (s) for interrupting the power supply to the motor vehicle, cooling elements, electrical conductors, control unit (s). The energy storage device can in particular have elements to be cooled, in particular energy storage cells and / or components of the power electronics of the energy storage device. The components are expediently preassembled in the motor vehicle before the assembly is installed.

The energy storage cells can in particular be designed as round cells for the electrochemical storage of energy. A round cell is usually accommodated in a cylindrical cell housing (English "cell can"). If the active materials of the round cell expand for operational reasons, the housing is subjected to tensile stress in the surrounding area. In this way, comparatively thin housing cross-sections can advantageously compensate for the forces resulting from the swelling. The cell housing is preferably made of steel or a steel alloy.

Typically, degassing openings can be provided in the energy storage cells in order to allow gases produced to escape from the cell housing. However, only one degassing opening can be provided per storage cell or round cell. Advantageously, at least one degassing opening per round cell is arranged so as to degas towards the outer rocker in the installation position.

The length-to-diameter ratio of the energy storage cells or round cells preferably has a value between 5 and 30, preferably between 7 and 15, and particularly preferably between 9 and 11. The length-to-diameter ratio is the quotient of the length of the cell housing of the round cell in the numerator and the diameter of the cell housing of the round cell in the denominator. In a preferred embodiment, the round cells can, for example, have an (external) diameter of approximately 45 mm to 55 mm. Furthermore, the round cells can advantageously have a length of 360 mm to 1,100 mm, preferably from approx. 450 mm to 600 mm, and particularly preferably from approx. 520 mm to 570 mm.

According to the technology disclosed here, it can be provided that the round cells are made from coated semi-finished electrode products. The cathode material or the anode material is expediently applied to carrier layers or carrier layer webs of the respective semifinished electrode. For example, the cathode material can be applied to a cathode carrier layer (for example aluminum) and the anode material can be applied to an anode carrier layer (for example copper) by coating.

According to the technology disclosed here, it can be provided that the round cells comprise at least one coated electrode semifinished product that has no mechanical separating edge perpendicular and / or parallel to the longitudinal axis of the round cells, which was produced by a separating process step after the electrode semifinished products were coated.

According to the technology disclosed here, it can be provided that the energy storage cells or round cells each comprise at least one coated electrode semifinished product with a rectangular cross-section, the length of the longer side of the electrode semifinished product essentially corresponding to or exceeding the total width of a carrier layer web that is used to form the electrode semifinished product with anode material or cathode material has been coated, so that the electrode semifinished product can or could be wound in the longitudinal direction of the carrier layer web after the coating without a further separation process step.

According to the technology disclosed here, the energy storage cells or round cells preferably run essentially parallel in their installation position (i.e. parallel, possibly with deviations that are irrelevant for the function) to the vehicle transverse axis Y. The vehicle transverse axis is the axis that is perpendicular in the normal position of the motor vehicle to the vehicle's longitudinal axis X and runs horizontally. However, the energy storage cells can also run parallel to the longitudinal axis X of the vehicle. They can also be arranged differently.

The energy storage cells are typically arranged in several layers within the storage housing in the direction of the vertical axis Z of the vehicle. The vertical axis of the vehicle is the axis which, in the normal position of the motor vehicle, runs perpendicular to the vehicle longitudinal axis X and vertically. A layer of energy storage cells is in particular a multiplicity of energy storage cells which are installed in the same plane in the storage housing and are essentially at the same distance from the bottom of the storage housing. The number of layers advantageously varies in the direction of the vehicle's longitudinal axis X. According to the technology disclosed here, the storage housing can have a top side whose outer housing contour is adapted to the lower inner contour of a passenger compartment of the motor vehicle, with the total height of the multiple layers in the installed position Adaptation to the housing contour in the direction of the vehicle longitudinal axis is varied in that in a first area of a position immediately adjacent round cells of the position in the installation position are further spaced apart in the direction of the vehicle longitudinal axis than immediately adjacent round cells in a second area of the same position, so that advantageously in In the first area, a further round cell of another layer further in one of the first intermediate area formed in the first area directly adjacent round cells penetrates than an identically formed further round cell of the other layer, which is in one of the second area unm penetrates the second intermediate area formed in the middle of adjacent round cells. The total height of the multiple layers is measured from the bottom of the storage housing to the upper end of the top layer at the respective point in the storage housing. The inner contour of the passenger cell is the contour that delimits the interior space of the passenger cell that is accessible to a vehicle user. In particular, the housing contour can be adapted to the inner contour in such a way that an expediently constant gap is provided between the top of the storage housing and the inner contour of the passenger compartment, which is preferably less than 15 cm or less than 10 cm or less than 5 cm.

According to the technology disclosed here, at least one can be in the installation position of the Energy storage device lowest position of the plurality of layers in the direction of the vehicle longitudinal axis from a front foot area of the storage housing that is adjacent in the installation position to the front footwell of the motor vehicle to a seat area of the storage housing, the seat area adjoining the rear seat bench of the motor vehicle.

According to the technology disclosed here, fewer layers can be arranged in at least one of the foot areas of the storage housing adjoining the front or rear footwell of the motor vehicle than in a seat area of the storage housing, with the seat area on the front seats and / or the rear seats (for example individual seats or rear bench) of the motor vehicle is adjacent. It can therefore advantageously be provided that, for example, only a lowermost layer of energy storage cells is provided in the storage housing in the front and / or rear foot area, whereas several layers are stacked one on top of the other in the front and / or rear seat area. This has the advantage that, in particular, the installation space below the front seats or below the rear seats can be used more efficiently in order to improve the electrical storage capacity of the motor vehicle.

In one embodiment, it can be provided that the plurality of energy storage cells in one layer are connected to one another by an adhesive applied over the plurality of energy storage cells in the same layer. The adhesive can expediently only be applied after the individual energy storage cells of a layer have been positioned with respect to one another, for example after the energy storage cells have been arranged in the storage housing. The individual energy storage cells of a layer can thus advantageously be fixed relative to one another in a cost-effective and space-saving manner. Polyurethane, polyamide or polyethylene, for example, can be used as the adhesive.

According to the technology disclosed here, cooling elements for cooling the energy storage cells can be provided between at least two layers of the energy storage cells, which can preferably be at least partially wave-shaped in cross section perpendicular to the vehicle transverse axis Y. In one embodiment, the cooling elements can be connected to a cooling circuit of the motor vehicle.

The current paths described here are implemented in particular by means of suitable connections between the energy storage cells. This can mean in particular that suitable conductive materials are used along a current path in order to connect poles of the energy storage cells to one another. A plus and a minus pole of energy storage cells connected in series in the system current path are typically connected along a system current path. Poles of the same polarity are typically connected to one another along a parallel current path. In particular, connections between poles of different polarity can also be connected to one another, i.e. each connection or connection point connects a positive pole with a negative pole along the system current path and a parallel current path connects at least two such connection points. A parallel current path is thus typically formed between two connections or connection points, each of the connections or connection points connecting opposite poles of energy storage cells to one another along a respective system current path.

The current paths or their connection points are implemented in particular by connections, connection elements or connection plates which are arranged outside the energy storage cells. They can also be designed integrally with the energy storage cells.

The parallel current paths can in particular be provided on both sides or at both longitudinal ends and / or opposite poles of the energy storage cells. In particular, they can be provided between equivalent points or voltages in the system current paths. Thus, parallel currents can flow not only between connection points, but also through energy storage cells and, for example, also through a total of two parallel current paths.

According to a preferred embodiment, each parallel current path has a current carrying capacity of at most 20 A. The parallel current paths can also have a current carrying capacity of at most 15 A or at most 25 A. A current carrying capacity between 15 A and 25 A can also be provided. This applies separately to each parallel current path. The current carrying capacity of a parallel current path is typically that value up to which a current can flow along a respective parallel current path. If this current is exceeded, then due to the formation of the parallel current path or the materials used for this, it is typically ensured that a further current flow or at least a further increase in the current is no longer possible.

In particular, it can also be provided that each parallel current path has a current-carrying capacity of at most 5% of the current-carrying capacity of each system current path. This can mean in particular that when comparing each parallel current path with each system current path, the current carrying capacity of the respective parallel current path is at most 5% the current carrying capacity of the respective system current path. Values other than 5% can also be used here, for example a maximum of 3% or a maximum of 7%. Such values have proven to be advantageous for typical applications, in particular in motor vehicles.

In particular, the parallel current paths can be designed as fuses. This can mean in particular that the respective parallel current path or the electrical conductor forming the parallel current path is designed in such a way that if the current-carrying capacity is exceeded, heating takes place briefly, which interrupts the parallel current path or destroys the material forming the parallel current path at least along a certain section. A further flow of current along the parallel current path is then no longer possible.

In more general terms, the parallel current paths can in particular be designed to be interrupted when the current-carrying capacity is exceeded. This means that if a current flows which exceeds the current-carrying capacity, the corresponding parallel current path interrupts itself due to its formation and prevents further current flow. In particular, corresponding materials that form the parallel current paths can be designed accordingly.

The energy storage cells can in particular be electrically connected along the system current paths and along the parallel current paths by electrically conductive connection plates. In particular, the connection points and the parallel current paths can be formed by electrically conductive connection plates. Typically, a connection plate forms two or more connection points and parallel current paths in between. As mentioned, each connection point connects two poles. A connection plate can be designed with the largest possible cross-section along a connection point for good current-carrying capacity. A current carrying capacity along a system current path or a connection point can in particular have a value of at least 500 A or 1,000 A or a maximum of 1,500 A. However, other values are also possible here, depending on the application. For a poorer current-carrying capacity, for example to form a parallel current path, in particular a smaller cross section can be used. A connection plate typically connects two energy storage cells along each system current path and connects the system current paths along one or more parallel current paths.

The energy storage cells can in particular be connected by electrically conductive webs along the parallel current paths. In particular, the parallel current paths can be formed by electrically conductive webs, in particular the connecting plates. These electrically conductive webs can in particular have a smaller and, in particular, significantly smaller cross section than the connections along the system current paths. For example, they can have a cross section which is at most 10%, at most 7%, at most 5% or at most 3% of the cross sections of the connection points or along the system current paths. The webs can in particular be designed as part of the connecting plates already mentioned. In this way, it can be achieved in a simple manner that the parallel current paths have a lower current carrying capacity.

According to a preferred embodiment, connection points between connections of energy storage cells, preferably two energy storage cells, with different polarity are formed along each system current path, the parallel current paths also being formed between each at least two connection points. As a result, a high current can flow along the system current paths, whereas only a limited current can flow along the parallel current paths. The connection points can be designed or implemented, for example, with the connection plates already mentioned above. By means of corresponding connection plates, in particular, predetermined combinations of system current paths and parallel current paths, in particular the desired number of system current paths, can be taken into account. For example, different connection plates can be used, depending on whether two, three or more layers of energy storage cells are used, and depending on how many system current paths are to be formed within these energy storage cells.

Longitudinal axes of the energy storage cells can in particular be aligned parallel to one another. This enables a compact arrangement which can advantageously utilize existing installation space.

Connections or connection points along a system current path typically alternate with respect to the respective longitudinal ends of the energy storage cells. This can mean, for example, that connection points of a system current path alternately run on a left side and a right side of the motor vehicle (when installing the energy storage cells transversely to the vehicle longitudinal axis X) or alternately at the front and rear (when installing the energy storage cells parallel to the vehicle longitudinal axis X).

The energy storage cells can in particular be in one, two, three or more layers be arranged. According to one possible embodiment, each system current path runs along one of the layers. This enables a simple design and the use of identical connecting elements or connecting plates, at least outside of interruptions, as will be described in more detail below, for example.

According to one embodiment, the energy storage cells are arranged in a first layer and a second layer. A first system flow path, a second system flow path and a third system flow path can be provided. Each system current path can run along three immediately adjacent energy storage cells in one layer and then further along three immediately adjacent energy storage cells in the other layer, which are spaced apart by one energy storage cell or one and a half energy storage cells. The spacing can be seen in particular along a direction along which the energy storage cells of a respective layer are arranged next to one another, for example along a vehicle longitudinal axis X or a vehicle transverse axis Y or in a horizontal plane when the motor vehicle is on a level surface. The spacing can in particular also be defined along a direction predetermined by the system current paths. Such an embodiment has proven to be particularly advantageous to the extent that three system current paths are to be provided in an arrangement with two layers of energy storage cells. Standardized connecting elements or connecting plates that can be reused as often as required can be used.

A course of a system current path along a plurality of energy storage cells in a layer typically means that the system current path extends along immediately adjacent cells in this layer. The cells are connected to one another accordingly.

With regard to the courses of system flow paths described here, it should be noted that these can in principle be continued according to the respectively specified course, the course then typically running again as described. The curves described can therefore basically be used as often as required.

A spacing by an entire energy storage cell or a plurality of entire energy storage cells can occur in particular when energy storage cells of different layers are arranged directly one above the other without their center points being offset from one another. If the cells of directly adjacent layers are offset from one another by half an energy storage cell, so that, for example, when viewed in cross section, a center point of an energy storage cell in one layer is below or above a center between two centers of energy storage cells in a layer immediately above or below, then in particular distances of half an energy storage cell, one and a half energy storage cells, etc. occur.

For possible implementation of the connections between the energy storage cells, reference is made to the accompanying drawing and the description given below, where corresponding designs are described, which in particular are also to be regarded as part of the disclosure.

According to one embodiment, the energy storage cells can be arranged in a first layer, a second layer and a third layer. The first system current path can alternately run between two directly adjacent energy storage cells of the first layer and one energy storage cell of the second layer, and the second system current path can alternate between two immediately adjacent energy storage cells of the third layer and an energy storage cell of the second layer. The respective energy storage cell of the second layer can in this case, viewed along the extent of the layers, for example viewed horizontally, be arranged further following one direction. As a result, an advantageous configuration with three layers and still only two system current paths can be achieved, with a very limited number of connecting elements or connecting plates typically to be used between the energy storage cells being required in this case as well. The second layer can in particular be arranged between the first layer and the third layer.

According to one embodiment, one or more interruptions are formed in one or more layers. No energy storage cells are present in an interruption. In other words, a distance between energy storage cells of a layer in an interruption can be greater than usual. The system current paths can bridge the interruption. This can mean, for example, that at least one or some of the system current paths run to the side of the interruption. In this way, for example, energy storage cells that directly adjoin the interruption can be connected to one another. The course of the system flow paths can deviate adjacent to each interruption. Suitable connecting elements or connecting plates can also be provided for this, which can be used depending on the number of layers, the number of system current paths and the size of the interruption. In the event of an interruption, system flow paths, which otherwise run along a layer, for example cross over. In particular, connections, connection points, connection elements or connection plates can be designed to run to the side of an interruption, that is to say in particular at the respective longitudinal ends of the energy storage cells.

The energy storage cells can in particular be connected to one another at their longitudinal ends by means of one type or several different types of connecting plates. In particular, one, two or three different types of connecting plates are sufficient for most designs, as will be explained in more detail below with reference to the drawings. Such connecting plates can be designed in particular for a corresponding configuration of layers and system flow paths as well as for possible interruptions. This allows suitable electrical connections to be made over any expansion with a very limited number of connection plates. As will be described in more detail below with reference to the drawing, one type of connecting plate is sufficient for simple designs. In the case of more complex designs and / or interruptions, two, three or four different types of connecting plates can be used, for example. In more general terms, the connection plates can also be referred to as cell connectors.

The connecting plates can be made flat, but they can also be curved or designed with a different course. They can have a constant thickness, but also a non-constant thickness.

According to one possible embodiment, the energy storage cells are designed as prismatic cells. In this case, too, the concept described here can be used to use parallel current paths with a significantly lower current carrying capacity compared to the system current paths.

The technology disclosed here also relates to a motor vehicle with an energy storage device as described herein. With regard to the energy storage device, all of the embodiments and variants described herein can be used.

In other words, there are typically several parallel and series connections in an electrical storage system, as a result of which system current and parallel current in embodiments according to the prior art typically share the same electrical path. Parallel currents typically arise from slightly different electrical internal resistances of energy storage cells connected in parallel.

In the event of a thermal event in an energy storage cell or battery cell, the respective cell can become low-resistance or is short-circuited internally. In such a situation it can happen that all cells connected in parallel are also short-circuited by the low-resistance cell. Such a short-circuit event (in cells connected in parallel) can put additional thermal stress on these cells, causing the cell temperature to rise. This increases the risk of a further thermal event in the cell that has already been short-circuited.

Cell connection concepts are therefore proposed herein which make it possible to separate the parallel current path from the system current path. The parallel current path is shown in particular with a significantly lower current carrying capacity, so that in the event of a short-circuit current between cells connected in parallel, this parallel current path serves as a fuse and thus a prolonged short-circuit situation is prevented or prevented.

• 1: eine Energiespeichereinrichtung gemäß dem Stand der Technik,
• 2: eine Illustration von System- und Parallelstrompfaden in einer bestimmten Ausführung,
• 3: eine Illustration von System- und Parallelstrompfaden in einer weiteren Ausführung,
• 4a, 4b bis 9a, 9b: Energiespeichereinrichtungen in jeweiligen Ausführungen,
• 10: unterschiedliche Arten von Verbindungsplatten,
• 11: eine Energiespeichereinrichtung mit prismatischen Zellen, und
• 12: eine weitere Energiespeichereinrichtung mit prismatischen Zellen.

The technology disclosed herein will now be described with reference to the accompanying drawings. Show:

• 1 : an energy storage device according to the state of the art,
• 2 : an illustration of system and parallel flow paths in a specific design,
• 3 : an illustration of system and parallel flow paths in a further version,
• 4a , 4b until 9a , 9b : Energy storage devices in respective designs,
• 10 : different types of connecting plates,
• 11 : an energy storage device with prismatic cells, and
• 12th : another energy storage device with prismatic cells.

1 shows an energy storage device 5 according to the state of the art. This has several energy storage cells 10 on, which are designed in the form of elongated round cells. In each case, electrical energy can be stored electrochemically.

1 shows a purely schematic side view, wherein the energy storage device 5 can of course also have a smaller or larger dimension.

As shown are the energy storage cells 10 in two superimposed layers of five energy storage cells each 10 arranged. she extend across the plane of the paper from 1 and are arranged parallel to one another with respect to their longitudinal axes. In between there is a wave-shaped cooling plate 20th . In the embodiment shown, a respective system current path basically runs along a respective layer. However, not all of the necessary connecting elements are shown for this, but merely an exemplary connecting element in the form of a connecting plate 35 shown, as it is typically used in designs according to the prior art. The connecting plate 35 is shown in dashed lines. As shown, it connects four energy storage cells, namely the energy storage cells Z1, Z3 of the upper layer and the energy storage cells Z2, Z4 of the lower layer. A positive pole and a negative pole are connected to one another along a respective system current path.

Due to the design of the connection plate shown 35 can create a system current path along each of the two layers of energy storage cells 10 flow, but a parallel current can also flow between the layers. In typical operation, this results in slightly different internal resistances of the individual energy storage cells 10 compensates for what is a desired effect of parallel currents.

As an example, consider the case that a short circuit occurs in the energy storage cell Z1. This can lead to significant heating of the energy storage cell Z1, which is also referred to as a thermal event. As shown is between the respective energy storage cells 10 a layer of a thermally insulating material 30th arranged, which prevents or slows down a possible spread of the heating. In the embodiment shown, however, it is possible that, for example, the energy storage cell Z2, which has the same polarity as the first energy storage cell Z1, suddenly emits an increased current due to the short circuit of the energy storage cell Z1 and therefore also overheats. A possible thermal event can thus occur in the energy storage device 5 spread.

2 shows, purely schematically, an energy storage device 5 with a total of four energy storage cells shown 10 to explain the concept of the technology disclosed here. First of all, it can be seen that, according to the design, a connecting plate used 36 two system current paths S1, S2 horizontally, ie along a respective position of energy storage cells 10 , get lost. These are each shown here with several arrows. In the present embodiment, there are two adjacent energy storage cells 10 connected along a system current path S1, S2. Such a connection can be referred to as a connection point, a first connection point V1 being present in the first system current path S1 and a second connection point V2 being present in the second system current path S2. A parallel current path is between two such connection points V1, V2 P. available, which, as already mentioned, serves to compensate for any slightly different internal resistances. This is a desirable effect in normal operation. In the event of a short circuit in one of the energy storage cells 10 however, this would no longer be desirable, as already described with reference to FIG 1 explained.

This is why the parallel current path is used here P. designed so that it only has a significantly lower current carrying capacity than the system current paths S1, S2. This is made possible by a significantly thinner design of the parallel current path P. in comparison to the system flow paths S1, S2, the parallel flow path P. present as a bridge 45 is trained. It should therefore be in one of the energy storage cells 10 If a short circuit occurs, that would affect the parallel current path P. in the jetty 45 The intended material melts as soon as the current-carrying capacity of the parallel current path P. is exceeded. The parallel current path P. would then no longer be available. The electrical connection is thus interrupted and a thermal event continues to spread via the energy storage cells 10 the energy storage device 5 is not possible anymore.

3 shows an energy storage device 5 in one to 2 different configuration. With the aid of the system flow paths S1, S2, excerpts from more complex courses of system flow paths are shown, which are exemplified with a connecting plate 37 are realized. In this case, too, there is a parallel current path P. between two respective connection points V1, V2, in each case two energy storage cells 10 , referring to the description of 2 is referred. This shows that the concept described here can also be used for more complex courses of system flow paths.

the 4a and 4b show an energy storage device 5 according to an embodiment. 4a shows a side view from one side and 4b shows a side view from an opposite side. For example, it can be 4a be a side view of a left side of a motor vehicle and at 4b a side view from a right side of a motor vehicle, or vice versa. The same applies to those described below 5a , 5b until 9a , 9b .

As shown, in the embodiment according to FIGS 4a , 4b two layers L1, L2 of Energy storage cells 10 present, the energy storage cells 10 in this and the figures described below, no longer with the reference symbol for a better overview 10 are designated, but rather are only shown as round circles. The polarity at the respective longitudinal end to be seen is indicated with (+) or (-).

The layers or the energy storage cells of different layers are offset from one another by half a cell in the horizontal direction. Thus, a rounding of a cell can partially intervene in a space between two other cells. In between, for example, cooling elements can be arranged, which, however, are not shown here.

It can also be seen that there are specific connecting plates on both sides 40 available. End-side connecting plates, ie those which are arranged on the far left or on the right, are designed differently than the connecting plates arranged between them 40 and are in these and in the others 5a , 5b until 9a , 9b with the reference number 40a referred to, regardless of the specific form. They are not included as part of any system flow path S. viewed.

The connecting plates arranged in between 40 are here designed in a butterfly shape. This means that respective system current paths S1, S2, which each extend along one of the layers L1, L2, along large-area horizontal sections of the connecting plates 40 are trained. Parallel current paths P. , which run vertically in this embodiment, are in contrast only with significantly less material in the respective connecting plates 40 executed, namely as respective webs, so that a respective fuse is implemented here in a simple manner.

the 5a , 5b show an alternative embodiment in which an interruption U is formed. In the case of the interruption U, an energy storage cell is missing 10 the second layer L2. As can easily be seen, connecting plates are adjacent and modified at the interruption U. 40b available. However, these also each basically have the form that the system current paths S1, S2 run along surfaces that are broad in terms of material, whereas parallel current paths P. run along only thin sections. In the present case, they ensure that the system current paths S1, S2 cross one another. The concept described herein can thus also be used across interruptions U, with such interruptions being able to be provided, for example, for a footwell of a motor vehicle in the other extension of the energy storage device 5 can intervene.

the 6a , 6b show an arrangement with two layers L1, L2 of energy storage cells 10 In contrast to the previous versions, there are not only two but three system current paths S1, S2, S3. These are by means of the respective adapted connecting plates 40c realized, with a connection between two immediately adjacent energy storage cells 10 the first layer L1 and two directly adjacent energy storage cells 10 of the second layer L2 is established, and furthermore a connection between two energy storage cells which are not adjacent, but are offset from one another by one and a half between them and which lie on different layers L1, L2, is established. Between these respective connections, which are again implemented over a large area, there are respective parallel current paths P. executed. As a result, three system current paths S1, S2, S3 can also be used in only two layers L1, L2 by means of standardized and uniform connection plates 40c , at least apart from the respective ends. Any system rung S. runs between three directly adjacent energy storage cells of one layer L and then further along three immediately adjacent energy storage cells of the other layer L.

the 7a , 7b show an embodiment with a total of three layers L1, L2, L3 of energy storage cells 10 . There are connecting plates 40d provided, which are identical and each lead a system current path S1, S2, S3 along a respective layer L1, L2, L3. Large-area connections are again provided for this purpose. Between these respective connection points of energy storage cells 10 of different polarity are parallel current paths P. provided, which, as already mentioned, are made with significantly thinner material sections and thus have the function of a fuse. In other words, the execution of the 7a , 7b as a generalization of the execution of the 4a , 4b can be understood in three ways. A generalization to even more locations is possible.

the 8a , 8b show an embodiment with likewise three layers L1, L2, L3 of energy storage cells 10 , but with only two system current paths S1, S2. These are about two different types of connector plates 40e , 40f realized, wherein, apart from terminals, the first system current path S1 alternately along two directly adjacent energy storage cells 10 the first layer L1 and an energy storage cell 10 the second layer L2 runs, and wherein the second system current path S2 alternately along two directly adjacent energy storage cells 10 the third layer L3 and an energy storage cell 10 the second layer L2 runs. It should be mentioned that even for Such complex courses of system flow paths only have two types of connection plates 40e , 40f sufficient.

the 9a , 9b show a design corresponding to that of FIG 8a , 8b In contrast to this, an interruption U is provided which extends over the second layer L2 and the third layer L3. Adjacent to the interruption U and to bridge it is a modified connecting plate 40g provided, which in an identical manner as previously described along the system current paths S1, S2 over a large area and along the parallel current path P. is only made narrow. In this way, an interruption can also be implemented in this constellation, for which, as shown in the in 9a no modified connecting plate is required, and in the in 9b The side to be seen is only a connection plate specifically modified for the interruption U. 40g is needed.

10 shows the already in the 4a , 4b until 9a , 9b connection plates shown separately. In particular, the connection plates can also be viewed as separate features of the technology disclosed here, independently of their integration into an energy storage device.

The connecting plate 40 has two straight connection points V1, V2 parallel to one another, between which a transverse web 45 is trained. The bridge 45 is thinner than the connection points V1, V2. The connection points V1, V2 typically each connect two directly adjacent energy storage cells.

The connecting plate 40a is designed to be flat and serves to connect energy storage cells at the end, ie it does not belong to the system current paths. The same applies to the others with the reference number 40a designated, end connecting plates.

The connecting plate 40b has a straight first connection point V1, which typically connects two directly adjacent energy storage cells, and a curved second connection point V2, in the present case running from top left to bottom right. In between is a footbridge 45 educated. The connecting plate 40b can in particular be used at an interruption where two system current paths cross.

The connecting plate 40c has a straight first connection point V1, a straight third connection point V3 running parallel thereto and a second connection point V2 arranged between them. The second connection point V2 leads from top left to bottom right and spans, viewed horizontally, the energy storage cells connected by the other connection points V1, V3. There are webs between the connection points V1, V2, V3 45 educated. The first and the third connection point V1, V3 typically each connect two energy storage cells arranged directly adjacent.

The connecting plate 40d has three straight, parallel connection points V1, V2, V3, between which transverse webs 45 are trained. The connection points V1, V2, V3 typically each connect two energy storage cells arranged directly adjacent to one another.

The connecting plate 40e has a straight first connection point V1 and a straight second connection point V2 arranged at an angle thereto. In between is a footbridge 45 arranged. While the first connection point V1 typically connects two directly adjacent energy storage cells of one layer, the second connection point V2 can connect energy storage cells of different layers.

The connecting plate 40f has two parallel, straight connection points V1, V2. In between there is a sloping bridge 45 arranged. The connection points V1, V2 can in particular produce connections via different layers of energy storage cells.

The connecting plate 40g has a first connection point V1 and a second connection point V2, which are each aligned straight and parallel to one another. The first connection point V1 typically connects two directly adjacent energy storage cells of one layer, and the second connection point V2 typically connects two immediately adjacent energy storage cells of another layer, which, however, have a greater distance from one another due to an interruption, for example. At least one further layer of energy storage cells is typically arranged between these layers. This location is made up of a transverse web 45 , which connects the connection points V1, V2, spans.

As shown are the junctions V typically designed as flat elements in the connecting plates, while the webs 45 are made considerably thinner. This increases the current carrying capacity of the webs 45 parallel current paths.

In principle, however, other connecting means can also be used to form connection points or parallel current paths, for example electrical wires or strands,

11 shows an embodiment of an energy storage device 5 , which compared to the previous designs with prismatic energy storage cells 10 is executed. These are shown in the present case in a plan view, with each energy storage cell 10 has a positive pole (+) and a negative pole (-) on the side shown. System current paths and parallel current paths are by means of corresponding connection plates 41 realized. In this case, too, the system current paths S1, S2, S3 are designed to have a particularly wide area, whereas the parallel current paths P. are only designed to be significantly narrower and thus with a significantly lower current-carrying capacity. The concept disclosed herein can thus also be used for prismatic cells.

12th shows an embodiment with prismatic cells 10 , which have side connections. There are only system current paths S1, S2, S3 between the three energy storage cells arranged on the left and the three centrally arranged energy storage cells 10 you can see that there are again parallel current paths in between P. educated. The system current paths S1, S2, S3 then run on the other side to the energy storage cells arranged on the right 10 gone and are therefore in 12th not to see.

For reasons of legibility, the expression “at least one” has been partially omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or indefinitely (e.g. the / an energy storage cell, the / a connecting element, etc.), the plurality of these should also be disclosed at the same time (e.g. the at least one energy storage cell, the at least one connecting element , Etc.).

The preceding description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

List of reference symbols

5

Energy storage device

10

Energy storage cell

20th

Cooling plate

30th

thermally insulating material

35

Connecting plate

36

Connecting plate

37

Connecting plate

40 - 40g

Connecting plate

41

Connecting plate

45

web

S.

System electricity paths

P.

Parallel current paths

V

Connection points

Claims (15)

Electrical energy storage device (5), - which has several energy storage cells (10), - wherein some of the energy storage cells (10) are electrically connected in series along a first system current path (S1) and some of the energy storage cells are electrically connected in series along a second system current path (S2), each system current path (S) having a current carrying capacity, - each system current path (S) being formed by means of several connection points (V), each connection point (V) connecting one pole of an energy storage cell (10) to a pole of a further energy storage cell (10) in the system current path (S), - Exclusively one or more parallel current paths (P) being formed between the system current paths (S), each parallel current path (P) running between a connection point (V) of a system current path (S) and a connection point (V) of another system current path (S), and - Each parallel current path (P) has a lower current carrying capacity than every system current path (S). Energy storage device (5) according to Claim 1 , each parallel current path (P) has a current carrying capacity between 15 A and 25 A or a maximum of 20 A. Energy storage device (5) according to Claim 1 or 2 , whereby each parallel current path (P) has a current carrying capacity of at most 5% of the current carrying capacity of each system current path (S). Energy storage device (5) according to one of the preceding claims, wherein the parallel current paths (P) are designed as fuses. Energy storage device (5) according to one of the preceding claims, wherein the parallel current paths (P) are designed to be interrupted when their current-carrying capacity is exceeded. Energy storage device (5) according to one of the preceding claims, wherein the connection points (V) and the parallel current paths (P) are formed by electrically conductive connection plates (40). Energy storage device (5) according to one of the preceding claims, wherein the Parallel current paths (P) are formed by electrically conductive webs. Energy storage device (5) according to one of the preceding claims, wherein longitudinal axes of the energy storage cells (10) are aligned parallel to one another. Energy storage device (5) according to one of the preceding claims, - The energy storage cells (10) being arranged in two, three or more layers (L), and - Each system current path (S) running along one of the layers (L). Energy storage device (5) according to one of the Claims 1 until 8th - wherein the energy storage cells (10) are arranged in a first layer (L1) and in a second layer (L2), - wherein a first system current path (S1), a second system current path (S2) and a third system current path (S3) are provided , and - each system current path (S) along three immediately adjacent energy storage cells (10) of one layer (L) and then further along three immediately adjacent energy storage cells (10) of the other layer (L), which are around an energy storage cell (10) or by one and a half Energy storage cells (10) are spaced apart, runs. Energy storage device (5) according to one of the Claims 1 until 8th - the energy storage cells (10) being arranged in a first layer (L1), a second layer (L2) and a third layer (L3), - the first system current path (S1) alternating between two immediately adjacent energy storage cells (10) of the first layer (L1) and an energy storage cell (10) of the second layer (L2), and - the second system current path (S2) alternating between two immediately adjacent energy storage cells (10) of the third layer (L3) and an energy storage cell (10) of the second layer (L2). Energy storage device (5) according to one of the Claims 9 until 11 - one or more interruptions (U) being formed in one or more layers (L), with no energy storage cells (10) being present in one interruption (U), and - the system current paths (S) bridging the interruption (U) . Energy storage device (5) according to one of the Claims 10 until 12th wherein the energy storage cells (10) are connected to one another at their longitudinal ends by means of at most two or three different types of connecting plates (40). Energy storage device (5) according to one of the Claims 1 until 7th , wherein the energy storage cells (10) are designed as prismatic cells. Motor vehicle with an energy storage device (5) according to one of the preceding claims.

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