DE102018202946A1 - Battery module for a battery of a motor vehicle and battery for a motor vehicle - Google Patents

Abstract

The invention relates to a battery module (1) for a battery (2) of a motor vehicle, comprising at least two spaced apart battery cells (3) and at least one associated cell barrier (4) at least partially disposed between the battery cells (3) Cell barrier (4) is at least partially formed of a first material (5), which changes its thermal conductivity when it exceeds or falls below a certain temperature value discontinuously. Furthermore, the invention relates to a battery (2).

Description

The invention relates to a battery module for a battery of a motor vehicle according to the preamble of patent claim 1. Furthermore, the invention relates to a battery for a motor vehicle according to the preamble of patent claim 8.

In electric mobility, batteries, in particular high-voltage accumulators, which are also referred to as traction batteries, play an increasingly important role in the propulsion of motor vehicles, in particular hybrid vehicles or electric vehicles. Currently, lithium-ion batteries are predominantly used as batteries in electrically powered motor vehicles. As a rule, individual battery cells are combined to form battery modules. The battery modules are in turn combined or switched to the battery. To make a range of the motor vehicle as large as possible, the batteries must each achieve the highest possible capacity and / or voltage, which explains the interconnection of the individual battery cells or battery modules.

If, for example, a cell-internal short circuit occurs on one of the, in particular lithium-ion, battery cells, a so-called thermal event of the battery cell can occur. This takes place first inside the battery cell, thereby the cell can burn through or burn through, which is accompanied by a self-reinforcing, heat-producing process. Due to the ever-increasing energy density of the batteries or high-voltage storage by, for example, ever higher packing densities of the battery cells, especially in the battery module, the danger that the adjacent battery cells of the battery cell, within which the thermal event occurs, due to the high heat development of the continuous cell also increases suffer a short circuit or a thermal event and thus go through. This can result in a chain reaction, a so-called domino effect, which can lead to the destruction of the entire battery.

Currently, high-voltage accumulators are cooled by active liquid circulation cooling. That's how it shows DE 10 2013 226 813 A1 a cooling device for a high-voltage accumulator comprising a heat sink, which can be flowed through by a refrigerant, wherein the heat sink is adapted to receive heat from the high-voltage accumulator and deliver it to the flowing refrigerant.

Further, the WO 2016/166659 A1 a battery module for a traction battery, wherein the battery module consists of a plurality of battery cells and a plurality of heat transfer elements. In this case, a cooling plate is used for heat transfer from the heat transfer elements.

Finally, the reveals EP 1 818 998 B1 a cell barrier for a battery module formed of a metal body and an insulating layer disposed on the surface of the metal body. The cell barrier is placed between individual cells of the battery module to electrically isolate between the cells of the battery module.

It is an object of the invention to develop a battery module for a battery of a motor vehicle or a battery such that in the case of a thermal event in which a battery cell, for example, due to a short circuit, produces heat, a transfer of heat to other battery cells as possible omitted.

This object is achieved by a battery module for a battery of a motor vehicle according to claim 1 and by a battery for a motor vehicle according to claim 8. Advantageous embodiments of the invention are the subject of the dependent claims and the description.

A battery module according to the invention for a battery, in particular a traction battery, of a motor vehicle has at least two battery cells spaced apart from one another and at least one associated cell barrier. The cell barrier is at least partially arranged between the battery cells.

In order to minimize or inhibit a transfer of heat in the event of a thermal event of a battery cell, for example due to a short circuit in the same, the respective cell barrier is at least partially formed of a first material, which its thermal conductivity when exceeding or falling below a certain temperature value unsteadily changes. Under a thermal event of a battery cell can be understood that this spontaneously goes into a self-reinforcing, heat-producing process. This can occur, for example, as a result of a cell-internal short circuit. In this case, the cell can burn through or burn through and develop a particularly large heat, which can skip to adjacent battery cells, whereby they can also suffer a short circuit and each pass into the thermal event itself. One can speak of a "runaway" of the battery cell or the battery. This can cause a chain reaction in the battery Motor vehicle, which is designed in particular as a high-voltage storage lead. Result of the chain reaction can be a complete destruction of the entire battery.

The material used according to the invention for the at least partial formation of the respective cell barrier has at least one characteristic property which can inhibit or prevent this runaway or the chain reaction. In particular, the characteristic property is a temperature-dependent thermal conductivity or the temperature dependence of the thermal conductivity. Simply put, the thermal conductivity is the property of a material or element or material to transport heat through it. In general, in most materials or materials, the thermal conductivity increases with increasing temperature, in particular at least slightly. So that a temperature transmission does not occur or is severely restricted at high temperatures, the material according to the invention changes its thermal conductivity discontinuously at a certain temperature or a certain temperature value. Under unsteady can be understood in the context of claim 1 in particular leaps and bounds, that is, the thermal conductivity on reaching the specific temperature value, which may be a material-specific characteristic in particular, greatly changes beyond the normally occurring temperature-dependent behavior of the heat conductivity. Thus, here too, discontinuity is analogous to its mathematical meaning, interpretable in the sense of a discontinuous function. Below the temperature value, the thermal conductivity can have a first value, which is in particular substantially smaller than a second value of the thermal conductivity above the temperature value. This can occur, for example, when the state of the material or the material changes.

If the material is chosen so that above the temperature value, the thermal conductivity, in particular significantly, is lower than below the temperature value, the transmission of heat above the temperature value can be particularly advantageously inhibited or prevented. That is, upon the occurrence of the thermal event described above, a temperature transfer from one battery cell to the other battery cell is difficult or prevented, whereby the chain reaction, which can also be referred to as a domino effect, at least can be delayed. The first material and thus the cell barrier can serve as heat flow control or work. Therefore, the material or the cell barrier can also be referred to as a heat flow switch. For example, the first material below about 130 to 150 degrees Celsius has a particularly high thermal conductivity, whereas at temperatures above 150 degrees Celsius it has a particularly low thermal conductivity. The material may for example be formed from an inhomogeneous material mixture, wherein at least one of the materials of the material mixture, in particular at a temperature which corresponds to the determined temperature value, changes its state of aggregation.

In addition, the material can advantageously have a high adaptability to rough substrates as a mechanical characteristic. Furthermore, it may be advantageous, in particular since the material can be in direct contact with the respective battery cell, that the material and thus at least part of the cell barrier has a particularly high electrical resistance. Alternatively, as the first material, a material or material mixture may be used whose thermal conductivity above the temperature value is higher than below the temperature value. Thus, a heat flow between adjacent battery cells could be inhibited at low temperature, whereby, for example, a faster heating of the respective battery cell to an optimum operating temperature may be possible.

In an advantageous embodiment of the invention, the first material is porous and has a fluid in cavities present thereby, which changes its state of aggregation at a temperature which corresponds to the temperature value. In other words, the first material has a porous internal structure, that is, it has a non-zero porosity. Due to the porosity not equal to zero, the material has in its interior cavities, which may be open-pore or closed, for example. Thus, the inner structure may be at least partially sponge-like and / or at least partially foam-like, it would also be possible to superimpose or mix the two inner structures. The cavities may be filled at least in total and / or in each case with the fluid. The fluid present in the cavities can be advantageously chosen so that it performs a change of its state of aggregation, for example, in particular from gaseous to liquid and vice versa, at a temperature corresponding to the temperature value at which a discontinuous or sudden increase or decrease of the thermal conductivity desired is. When selecting the fluid, further framework conditions which occur within the pores or in cavities of the material, such as pressure, should be taken into account. By forming the material as a porous structure filled with the fluid In a particularly simple manner, a cell barrier can be realized which, depending on the temperature, changes its thermal conductivity when the temperature value is exceeded or undershot so that heat is not transferred from a battery cell passing through a thermal event to an adjacent battery cell as far as possible.

In an advantageous embodiment of the invention, the first material at a temperature corresponding to the temperature value, a phase transition. A phase transition or a phase transformation is the change or conversion of at least one phase of the material into another phase. The change of the phase is here in particular temperature-dependent, but may additionally depend on further state variables such as ambient pressure or pressure in the material and / or the like. More specifically, when the temperature value is reached, the change in phase occurs in the material because, for example, phase interfaces can form at which properties, in particular the thermal conductivity, can change abruptly. By using a material which has a phase transition when passing through the temperature value, a change in the thermal conductivity may be discontinuous. A large number of materials, in particular multicomponent systems, that is to say substances which do not consist only of one chemical element in each case, are thus suitable for use in the cell barrier, which makes possible a particularly flexible design of the same and thus of the battery module according to the invention.

In an advantageous embodiment of the invention, the cell barrier is formed from at least two layers, wherein a first of the layers is at least partially formed from the first material. By virtue of the at least two layers, which may in particular be arranged adjacent to one another, it is possible, for example, to predetermine or predetermine a further property of the cell barrier in addition to its thermal conductivity. Alternatively or additionally, the at least one further layer, which is different from the first layer, can serve, for example, as a carrier for the first layer. By constructing the cell barrier as formed from at least two layers, a cell barrier can be realized which is particularly advantageous for the, in particular targeted, transfer of heat between battery cells.

In a further advantageous embodiment of the invention, a further of the layers is at least partially formed from a second material, which has a higher mechanical stability compared to the first material. By using the second material, which has a higher mechanical stability than the first material, in particular a particularly high mechanical stability, the at least one further layer can be used, for example, as a support or support structure or frame for the cell barrier or the battery cell. For example, the material may be at least partially made of, in particular hard, rubber, which, for example, has a particularly low thermal conductivity, but for a particularly high electrical resistance.

In an advantageous embodiment of the invention, a further of the layers is at least partially formed of a third material, which is a thermal insulator. Its mechanical properties could on the one hand additionally be a particularly rigid material, or alternatively also a flexible material. The thermal conductivity of a thermal insulator is particularly low, in addition, as a rule, also its electrical conductivity. The third material or the further layer to be used according to the invention may be designed such that it serves not only as a layer between two battery cells but alternatively or additionally a combination of several battery cells separated by the other layers or the at least one first layer of the cell barrier Whole encased. This results in the advantage that the battery cells in their entirety or the battery module are particularly well protected against environmental influences and additionally the other way round, the environment is particularly well protected against a possibly due to the thermal event itself destructive battery module.

In an advantageous embodiment of the invention, the first layer is at least partially formed from the first material, which increases its thermal conductivity discontinuously when a first temperature value is exceeded. The second layer is formed from a further, first material, which discontinuously lowers its thermal conductivity when a second temperature value, which is higher than the first temperature value, is exceeded. By arranging in each case a different first material in at least one of the layers of the cell barrier and the possibility that one of the first materials increases its thermal conductivity as the temperature increases, while the other first material reduces its thermal conductivity as the temperature increases, a temperature window can be determined become. These temperature windows can now be configured by using the first materials so that the cell barrier is particularly thermally conductive within this temperature window. For example, heat from the respective battery cell, for example, to another cooling system or similar deliver be, or heat can be exchanged particularly easily between the individual battery cells within the temperature window. At a temperature above the upper temperature value of the temperature window, the thermal conductivity of the cell barrier decreases, so that propagation of the thermal event of a continuous cell to other battery cells can be prevented. Due to the lower temperature value or below the lower temperature value of the temperature window, the thermal conductivity of the cell barrier also decreases, so that, for example, the operating temperature of the respective battery cell can be achieved particularly advantageously.

Furthermore, the invention comprises a battery for a motor vehicle, which has at least one battery module according to the invention. Advantages and advantageous embodiments of the battery module are to be regarded as advantages and advantageous embodiments of the battery and vice versa.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or in isolation.

• Die einzige Fig. zeigt in schematischer Seitenansicht ein erfindungsgemäßes Batteriemodul für eine Batterie eines Kraftfahrzeugs, mit wenigstens zwei voneinander beabstandeten Batteriezellen und mit wenigstens einer zugehörigen Zellbarriere.
• Die Fig. zeigt ein Batteriemodul 1 für eine Batterie 2 eines Kraftfahrzeugs, mit wenigstens zwei voneinander beabstandeten Batteriezellen 3 und mit wenigstens einer zugehörigen Zellbarriere 4. Dabei ist die wenigstens eine Zellbarriere 4 zumindest teilweise zwischen den Batteriezellen 3 angeordnet.

The invention will now be explained in more detail with reference to a preferred embodiment and with reference to the drawings. It shows:

• The single FIGURE shows a schematic side view of a battery module according to the invention for a battery of a motor vehicle, with at least two spaced-apart battery cells and at least one associated cell barrier.
• The figure shows a battery module 1 for a battery 2 a motor vehicle, with at least two spaced-apart battery cells 3 and with at least one associated cell barrier 4 , It is the at least one cell barrier 4 at least partially between the battery cells 3 arranged.

In the case of a thermal event in which one of the battery cells 3 , For example, due to a short circuit, produces heat, in particular self-reinforcing and thereby excessively heated, so that there is a so-called Durchschmoren the battery cell 3 can come, it is beneficial for the battery 2 in that the transfer of the heat produced during the thermal event also to the other battery cells 3 possibly omitted. This is the respective cell barrier 4 at least partially made of a first material 5 formed, which changes its thermal conductivity when it exceeds or falls below a certain temperature unsteady. The material 5 acts in the cell barrier 4 thus between at least two battery cells 3 as a heat flow control and can be referred to as a so-called heat flow switch. That's the material 5 For example, designed so that the thermal conductivity, which may be temperature-dependent over the entire temperature range, for example, but up to about 150 degrees Celsius is particularly large or larger than in a temperature range from 150 degrees Celsius, where the thermal conductivity in particular compared to that below the temperature value of 150 degrees Celsius temperature range, less or less.

The thermal conductivity of the material 5 and thus at least part of the cell barrier 4 is thus variable in particular. Ideally, the material becomes 5 so chosen that the cell barrier 4 in general, especially because of their proximity to the battery cells 3 , has a particularly high electrical resistance or is an electrical insulator. Advantageously, the first material 5 porous, meaning that there are cavities in its interior. These cavities are advantageously at least partially filled with a fluid or have a fluid which changes its state of aggregation at a temperature which corresponds to the temperature value. You can use the material 5 thus see as inhomogeneous material, wherein at least one component or a material component of the material 5 its state of aggregation, in particular the temperature value, can change. The material 5 thus partially changes its state of aggregation. Alternatively or additionally, advantageously, the first material 5 at a temperature corresponding to the temperature value, have a phase transition. This phase transition can include, for example, the change of the state of aggregation, and / or at least one other material-specific order parameter. In this case, the order parameter is advantageously to be selected such that the material to be considered as a physical system 5 a phase transition, in particular at a temperature which corresponds to the temperature value, performs or runs through, which is subject to a particular abrupt or discontinuous change in particular the thermal conductivity or has.

Advantageously, the cell barrier 4 at least two layers 6 and 7 formed, wherein a first of the layers 6 at least partially from the first material 5 is trained. Advantageously, another one of the layers 7 at least partly from a second material 8th formed, which compared to the first material 5 may have or have a higher mechanical stability. The second material 8th For example, a hard and / or rubbery and / or contributing to the mechanical stabilization of the battery module material and / or formed of a material mix material 8th its being made of the material 8th trained layer at least partially can take over the functions of a frame. So can the second material 8th for example, have a certain three-dimensional structure. In this case, its thermal conductivity and its electrical conductivity are advantageously low. Furthermore, the cell barrier 4 advantageously at least partially made of a third material 9 be formed, which is a thermal insulator. This has particularly advantageously a particularly high thermal stability, for example, this can be heat resistant to over 1000 degrees Celsius and in particular is not flammable. This can for example be designed as a foam and multiple battery cells 3 of the battery module 1 thermally against an environment of the battery 2 or the battery module 1 isolate. The cell barrier 4 may alternatively be designed so that it completely between the battery modules 1 or respective battery modules 1 is arranged.

In an advantageous embodiment of the battery module 1 is the first layer 6 at least partially from the first material 5 formed, which increases its thermal conductivity when exceeding a first Temperaturwerst discontinuous and the second layer 7 is from another first material 5 ' formed, which discontinuously decreases its thermal conductivity when exceeding a second temperature value, which is higher than the first temperature value. This makes it possible to form a temperature window with a first low temperature value and a second higher temperature value, so that a particularly good heat exchange between the cells can be realized within the temperature window. By contrast, the cell barrier is below the first temperature value and above the second temperature value 4 particularly efficient in inhibiting or preventing the heat exchange between respective adjacent battery cells 3 , Thus, there is the benefit of an upper temperature value, which increases the likelihood of a battery cell blowing through 3 or a propagation of the thermal event reduced by a so-called domino effect, in addition an isolation in a lower temperature range possible. This temperature range can for example be chosen so that the cell barrier 4 can be used as a good thermal insulator or as a heat barrier, so that the respective battery cell 3 advantageously can be heated particularly quickly to their respective optimum operating temperature.

LIST OF REFERENCE NUMBERS

1

battery module

2

battery

3

battery cell

4

cell barrier

5

first material

6

first shift

7

another layer

8th

second material

9

third material

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013226813 A1 [0004]
• WO 2016/166659 A1 [0005]
• EP 1818998 B1 [0006]

Claims (8)

Battery module (1) for a battery (2) of a motor vehicle, comprising at least two spaced-apart battery cells (3) and at least one associated cell barrier (4), which is at least partially disposed between the battery cells (3), characterized in that the respective Cell barrier (4) is at least partially formed of a first material (5), which changes its thermal conductivity when it exceeds or falls below a certain temperature value discontinuously. Battery module (1) to Claim 1 , characterized in that the first material (5) is porous and in cavities present thereby has a fluid which changes its state of aggregation at a temperature which corresponds to the temperature value. Battery module (1) to Claim 1 or 2 , characterized in that the first material (5) has a phase transition at a temperature which corresponds to the temperature value. Battery module (1) according to one of the preceding claims, characterized in that the cell barrier (4) is formed from at least two layers (6, 7), wherein a first of the layers (6, 7) consists at least partially of the first material (5). is trained. Battery module (1) to Claim 4 , characterized in that a further of the layers (6, 7) is at least partially formed from a second material (8) which has a higher mechanical stability compared to the first material (5). Battery module (1) to Claim 4 or 5 , characterized in that a further of the layers (6, 7) is at least partially formed of a third material (9), which is a thermal insulator. Battery module (1) according to one of the preceding claims, characterized in that the first layer (6, 7) is at least partially formed from the first material (5), which increases its thermal conductivity discontinuously when a first temperature value is exceeded and the second layer (6 , 7) is formed from a further, first material (5 ') which discontinuously lowers its thermal conductivity when a second temperature value, which is higher than the first temperature value, is exceeded. Battery (2) for a motor vehicle, characterized in that the battery (2) comprises at least one battery module (1) according to one of the preceding claims.

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