WO2019166335A1

WO2019166335A1 - Battery module for a battery of a motor vehicle, and battery for a motor vehicle

Info

Publication number: WO2019166335A1
Application number: PCT/EP2019/054405
Authority: WO
Inventors: Sebastian Scharner; Florian SCHOEWEL; Michael Huber; Christoph Riether; Sonia Dandl
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2018-02-27
Filing date: 2019-02-22
Publication date: 2019-09-06
Also published as: DE102018202946A1

Abstract

The invention relates to a battery module (1) for a battery (2) of a motor vehicle, comprising at least two battery cells (3) which are at a distance from one another and comprising at least one associated cell barrier (4) which is arranged at least partially between the battery cells (3), wherein the respective cell barrier (4) is formed at least partially from a first material (5) which discontinuously changes its thermal conductivity when a specific temperature value is exceeded or undershot. The invention also relates to a battery (2).

Description

Battery module for a battery of a motor vehicle and battery for a motor vehicle

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. In the case of electrically driven motor vehicles, predominantly lithium-ion batteries are currently being used as batteries. 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 at one of the, in particular lithium-ion, battery cells, a so-called thermal event of the battery cell can occur. This takes place once inside the battery cell, thereby the cell can be burned or burned, something with itself

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 a short circuit

or suffer a thermal event and thus go through. This can result in a chain reaction, a so-called domino effect, which

or which can lead to the destruction of the entire battery. Currently, high-voltage accumulators are cooled by active liquid circulation cooling. Thus, DE 10 2013 226 813 A1 shows 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.

Furthermore, WO 2016/166659 A1 discloses 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. Here, a cooling plate is used for

Heat transfer from the heat transfer elements.

Finally, EP 1 818 998 B1 discloses a cell barrier for a battery module, formed of a metal body and an insulating layer, which is arranged 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 further develop a battery module for a battery of a motor vehicle or a battery such that in the case of

Thermal events in which a battery cell, for example due to a short circuit, produces heat, a transfer of heat to others

Battery cells possibly 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 solved according to claim 8. Advantageous embodiments of the invention are the subject of the dependent claims and the description.

An inventive battery module for a battery, in particular a

Traction battery, a motor vehicle has at least two spaced-apart battery cells and at least one associated cell barrier. The cell barrier is at least partially arranged between the battery cells.

In order now to transfer heat in the case of a thermal event of a

Battery cell, for example, due to a short circuit in the same, as possible to stem or inhibit, the respective cell barrier is at least partially formed of a first material, which changes its thermal conductivity when exceeding or falling below a certain temperature value unstably. Under A thermal event of a battery cell can be understood to spontaneously go 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 of a "pass" of the battery cell

or speak the battery. This can lead to a chain reaction in the battery of the motor vehicle, which is designed in particular as a high-voltage storage. 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, heat through it

transport. It usually increases in most materials, respectively

Materials the thermal conductivity with increasing temperature, in particular at least slightly on. 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 in particular a

material-specific characteristic variable, which greatly changes beyond the normally occurring temperature-dependent behavior of the thermal 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

Thermal conductivity, in particular, is lower than below Temperature value, the transfer of heat above the temperature value can be particularly advantageous 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, a particularly high thermal conductivity, whereas at temperatures above 150 degrees Celsius, a particularly low

Has 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 the determined

Temperature value corresponds to its state of aggregation changes.

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

Temperature value. Thus, a heat flow between adjacent battery cells could be inhibited at a low temperature, for example, a faster

Heating the respective battery cell to an optimal 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, an overlay would also be possible

or mixture of the two internal structures. The cavities can in total and / or at least partially filled with the fluid. The fluid present in the cavities can be advantageously chosen so that it undergoes a change of its state of aggregation, for example, in particular from gaseous to liquid and vice versa, at a temperature which corresponds to the temperature value at which a discontinuous or sudden increase

or waste of the thermal conductivity is desired. 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, a cell barrier can be realized in a particularly simple manner

temperature dependent when exceeding or falling below the temperature value their

Thermal conductivity changes such that a transfer of heat from a thermal event passing through a battery cell on adjacent battery cell as possible avoided.

In an advantageous embodiment of the invention, the first material in a

Temperature, which corresponds 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 can additionally of other state variables such as ambient pressure

or pressure in the material and / or the like depend. 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 the at least two layers, which may be arranged in particular lying against each other, for example, another

Property of the cell barrier can be specified in addition to their thermal conductivity or be specified. 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 invention according to

The third material or the further layer that is used can be designed such that it not only serves as a layer between two battery cells, but alternatively or additionally encapsulates in its entirety a combination of a plurality of battery cells separated by the other layers or the at least one first layer of the cell barrier. 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 from another, first Material formed, which its thermal conductivity when exceeding a second

Temperature value which is higher than the first temperature value, discontinuously lowered. 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. This temperature window can through the

Use of the first materials are now designed so that the cell barrier is particularly thermally conductive within this temperature window. So can

For example, heat from the respective battery cell, for example, to another KOhlsystem or comparable will give off, or heat can be exchanged particularly easily within the temperature window between individual battery cells. At a temperature above the upper temperature value of the temperature window, the thermal conductivity of the cell barrier decreases, so that a

Propagation of the thermal event of a continuous cell to others

Battery cells can be prevented. By 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 feature combinations 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 are not only in the respectively indicated combination, but also in others

Combinations or used alone.

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 an inventive

Battery module for a battery of a motor vehicle, comprising at least two spaced-apart battery cells and at least one associated cell barrier.

The figure shows a battery mode! 1 for a battery 2 of a motor vehicle, with at least two spaced battery cells 3 and at least one associated cell barrier 4. The at least one cell barrier 4 is at least partially arranged between the battery cells 3.

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-boosting and thereby excessively heated, so that so-called burn through of the battery cell 3 can occur, it is advantageous for the battery 2, that the transmission of the heat produced during the thermal event also fails as far as possible to the other battery cells 3. For this, the respective cell barrier 4 is at least partially formed from a first material 5, which its

Thermal conductivity when exceeding or falling below a certain

Temperature value changes discontinuously. The material 5 thus acts in the cell barrier 4 between at least two battery cells 3 as heat flow control and can be referred to as a so-called heat flow switch. So the material is 5

For example, designed so that the thermal conductivity, which can be temperature-dependent over the entire temperature range, but for example, a total of up to about 150 degrees Celsius is particularly large or larger than in one

Temperature range from 150 degrees Celsius, where the thermal conductivity is lower or significantly lower, in particular compared to the lying below the temperature value of 150 degrees Celsius temperature range.

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 5 is selected so that the cell barrier 4 as a whole has a particularly high electrical resistance or is an electrical insulator, in particular due to its proximity to the battery cells 3. Advantageously, the first material 5 is porous, that is to say that cavities are present 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. One can thus see the material 5 as inhomogeneous material, wherein at least one component or a material component of the Material 5 can change its state of aggregation, in particular the temperature value. The material 5 thus partially changes its state of aggregation. Alternatively or additionally, the first material 5 can advantageously have a phase transition at a temperature which corresponds to the temperature value. This

Phase transition may include, for example, the change of the state of aggregation, and / or at least one other material-specific order parameters. In this case, the order parameter is advantageously to be selected so that the material 5 to be considered as a physical system performs or passes through a phase transition, in particular at a temperature which corresponds to the temperature value, which undergoes or has a particularly abrupt or unsteady change, in particular of the thermal conductivity.

Advantageously, the cell barrier 4 is formed at least from two layers 6 and 7, wherein a first of the layers 6 is at least partially formed from the first material 5. Advantageously, a further of the layers 7 is at least partially formed from a second material 8, which may have or have a higher mechanical stability compared to the first material 5. The second material 8 may, for example, a hard and / or rubber-like and / or contributing to the mechanical stabilization of the battery module and / or from a

Be material mix formed material 8, wherein the layer formed from the material 8 at least partially can take over the functions of a frame. For example, the second material 8 may have a specific three-dimensional structure. In this case, its thermal conductivity and its electrical conductivity are advantageously low. Furthermore, the cell barrier 4 can advantageously be formed at least partially from a third material 9, 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 isolate several battery cells 3 of the battery module 1 thermally against an environment of the battery 2 and the battery module 1. As an alternative to the FIGURE, the cell barrier 4 may be designed such that it is completely arranged between the battery modules 1 or respective battery modules 1.

In an advantageous embodiment of the battery module 1, the first layer 6 is at least partially formed from the first material 5, which increases its thermal conductivity when exceeding a first Temperaturwerst discontinuous and the second layer 7 is formed from a further first material 5 ', which its thermal conductivity during Exceeding a second temperature value, which is higher than the first

Temperature value is unstably lowered. This makes it possible to form a temperature window with a first low temperature value and a second higher temperature value, so that within the temperature window a particularly good

Heat exchange between the cells is feasible. On the other hand, below the first temperature value and above the second temperature value, the cell barrier 4 is particularly efficient in inhibiting the heat exchange between respective adjacent battery cells 3. Thus, the advantage of an upper temperature value, which increases the likelihood of burnout of a battery cell 3 and a spread 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 be selected, for example, such 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 up very quickly to its respective optimum operating temperature.

LIST OF REFERENCE NUMBERS

battery module

battery

battery cell

cell barrier

first material first layer

additional layer second material third material

Claims

claims

1 . Battery module (1) for a battery (2) of a motor vehicle, with at least two spaced-apart battery cells (3) and with at least one

associated cell barrier (4), which at least partially between the

Battery cells (3) is arranged,

characterized in that

the respective cell barrier (4) is at least partially formed from a first material (5), which changes its thermal conductivity discontinuously when it exceeds or falls below a certain temperature value.

2. Battery module (1) according to claim 1,

characterized in that

the first material (5) is porous and has, in cavities present thereby, a fluid which changes its state of aggregation at a temperature which corresponds to the temperature value.

3. Battery module (1) according 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.

4. 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) is formed at least partially from the first material (5).

5. Battery module (1) according to claim 4,

characterized in that another of the layers (6,

7) at least partially made of a second material

(8) is formed, which in comparison to the first material (5) has a higher mechanical stability.

6. Battery module (1) according to claim 4 or 5,

characterized in that

a further of the layers (6, 7) at least partially made of a third material

(9) which is a thermal insulator.

7. Battery module (1) according to one of the preceding claims,

characterized in that

the first layer (6, 7) is formed at least partially from the first material (5), which has its thermal conductivity when a first material is exceeded

Temperature value increases discontinuously and the second layer (6, 7) of a further, first material (5 ') is formed, which is its thermal conductivity at

Exceeding a second temperature value, which is higher than the first temperature value, discontinuously decreased.

8. battery (2) for a motor vehicle,

characterized in that

the battery (2) has at least one battery module (1) according to one of the preceding claims.