DE102022104897A1 - Battery for an electrically drivable motor vehicle, method for operating a battery and motor vehicle - Google Patents

Abstract

The invention relates to a battery (1, 2), a motor vehicle (3) and a method for operating such a battery (1, 2). A non-Newtonian cooling liquid (4) of the battery (1) is designed to flow around the battery cell arrangement (6) with a lower viscosity in a first viscosity state and in a second viscosity state in which the cooling liquid (4) is more viscous than in the first viscosity state due to shear stress or is to form a damping element (10) in the housing (5) for the battery cell arrangement (6). Alternatively, the non-Newtonian cooling liquid (4) of the battery (2) is designed to flow around the battery cell arrangement (6) with a higher viscosity in a first viscosity state and in a second viscosity state in which the cooling liquid (4) has a lower viscosity compared to the first viscosity state due to shear stress is or will wash around the battery cell arrangement (6).

Description

The present invention relates to a battery for a motor vehicle that can be driven or moved electrically. In particular, the battery is a traction battery for the motor vehicle. Furthermore, the invention relates to a method for operating such a battery. In addition, the invention relates to a motor vehicle that is equipped with such a battery.

In order to be able to store as much electrical energy as possible in electrically driven or electrically propelled motor vehicles (e.g. hybrid motor vehicles or purely electrically driven motor vehicles) for an advantageously particularly long driving range of the motor vehicle, secondary batteries (electrical accumulators) are used on board the motor vehicle, for example as High-voltage storage or traction battery are called. Nowadays, these are particularly bulky and space-intensive, as a result of which there are currently difficulties with regard to the packaging and overall mass of the motor vehicle when designing electrically driven motor vehicles. In addition, peripheral assemblies of electrical drive components, such as lubricant reservoirs, refrigerant reservoirs, associated fluid pumps, corresponding fluid line networks, etc., require additional installation space and contribute to the particularly high mass of the motor vehicle.

The packaging and mass problems are further aggravated by safety devices having to be provided specifically for the energy store or the battery in order to ensure particularly advantageous crash safety for the occupants of the motor vehicle. For example, crash structures are to be provided on or in the battery, by means of which impact accelerations occurring in a crash or accident and affecting the battery can be damped or braked in a defined manner along predetermined load paths. This is intended to prevent the battery, which is heavy and large, from being subjected to such accelerations as a result of which the battery is severely damaged. Measures must also be taken to slow down exothermic overreactions of one or more of the battery cells arranged inside the battery (also known as thermal runaway, thermal multiplication, thermal runaway or thermal propagation), caused in particular by an accident, and to propagate the exothermic overreaction further battery cells are slowed down and/or impeded, ideally completely prevented. Excessive deformation, in particular due to a fracture, of a battery cell can result in the fractured battery cell thermally running away and as a result dissipating an excessive amount of heat to its surroundings, in particular to at least one other battery cell. As a result, the other battery cell is affected, which can cause it to thermally run away itself. In this respect, the thermal runaway can propagate through the battery cells, which could lead to a fire, in particular to an explosion of the battery. Therefore, various measures are already being taken today to counteract thermal runaway or to prevent it from occurring.

So there are difficulties in the conception or in the production of such batteries that are intended for use as a traction battery in a motor vehicle. Designing a battery to be particularly safe and/or particularly mass-efficient requires a great deal of effort and a particularly complicated structure for the battery. There is a conflict of objectives between the need for particularly stable and therefore mass-intensive crash structures and the need for particularly light electrical energy stores or batteries.

The DE 10 2014 218 023 A1 proposes a mass coupling arrangement in which a mass object, for example a battery, is attached to a vehicle frame via a mass receiving element filled with a thixotropic and/or rheopexic liquid. In the event of a crash, the mass object compresses the liquid, and the liquid is diverted out of the mass absorption element or into the mass absorption element by a coupling means. The liquid may be the battery coolant.

It is the object of the invention to create a particularly crash-safe, electrically driven motor vehicle which is also particularly light in design and can therefore be operated in a particularly energy-efficient and low-emission manner.

This object is solved by the subject matter of the independent patent claims. Further possible configurations of the invention are disclosed in the dependent claims, the description and the figures. Features, advantages and possible configurations presented in the description for one of the subject-matters of the independent claims are at least analogous as features, advantages and possible configurations of the respective subject-matter of the other independent claims and of any possible combination of the subject-matters of the independent claims, where applicable in conjunction with one or more of the subclaims.

According to the invention, a battery for an electrically drivable motor vehicle, for example for a hybrid motor vehicle, a purely electrically drivable motor vehicle (“electric vehicle”), etc., is proposed. The battery can be a primary (non-rechargeable) battery or a secondary (rechargeable) battery. In particular, the battery is a traction battery for the motor vehicle. The battery has a housing and a battery cell arrangement arranged in the housing. In other words, the battery cell arrangement, which is formed from a large number of battery cells or battery cell packs, is held in a fixed position in the housing. In order to cool the battery, in particular the battery cell arrangement fastened in the housing, the battery has a cooling liquid which flows around the battery cell arrangement during operation, for example in charging operation and/or in discharging operation. In this case, the battery cell arrangement is cooled in particular by flushing the battery cell arrangement, the battery cell packs and/or the battery cells directly (immersion cooling).

The cooling liquid, which can be present in particular as a solution, as a heterogeneous or homogeneous emulsion or as a suspension, is a non-Newtonian fluid. In a non-Newtonian fluid, there is a non-linear relationship between a shearing stress (often represented by the symbol τ in technical literature) and a shear rate (often represented by the symbol γ̇ in technical literature) of the liquid. To put it simply: A viscosity (thickness, often represented by the symbol η in the technical literature) of the non-Newtonian liquid increases or decreases with continuous shear stress or a constant change in shear stress. Where viscosities are compared herein, the terms "lower viscosity" and "higher viscosity" are to be considered relative to one another. A first viscosity state characterizes a state of the cooling liquid in which the viscosity of the cooling liquid is and remains stable, ie for example a state of rest of the cooling liquid. The cooling liquid always begins to strive towards the first viscosity state as soon as it is not (or no longer) subjected to shear stress or to a lesser shear stress. A second viscosity state characterizes another state of the cooling liquid to which or towards which the cooling liquid begins to strive whenever it is subjected to a shear stress and/or a shear stress change. It may be that the cooling liquid only fully reaches the first viscosity state or resting state after a resting phase. A sudden transition between the viscosity states is also conceivable. According to the invention, in the event of a crash or fault, the coolant is used for the physical and thermal protection of the battery cells and their periphery.

According to a first aspect of the invention, the cooling liquid of the battery is designed to flow around the battery cell arrangement in the first viscosity state with a lower viscosity (as an example of understanding: for example like water). In the first viscosity state, the cooling liquid therefore functions primarily or entirely as a conditioning liquid in order to cool and/or heat the battery cell arrangement in order to bring an operating temperature of the battery cell arrangement to an optimum level or to keep it there. The first viscosity state of the coolant is present in particular during normal operation of the battery or of the motor vehicle equipped with the battery, with the coolant being pumped through a cooling circuit at a lower viscosity at common operating temperatures and pressures in order to cool/heat the battery cell arrangement.

Since - as already mentioned - the cooling liquid is a non-Newtonian fluid, the viscosity of the cooling liquid can change. The cooling liquid assumes the second viscosity state, in which the cooling liquid is or becomes more viscous (ie more viscous/viscous than water) compared to the first viscosity state due to a shearing load. The coolant assumes the second viscosity state, for example due to a crash load. Thus, in the event of a crash, a damping element is or will be formed in the interior of the housing for the battery cell arrangement by means of the coolant. This means that the non-Newtonian coolant acts as a safety element for the battery, in particular for the battery cell arrangement, at least in the event of a crash. For example, the coolant acts as a stiffening member when subjected to shear stress or shear stress change due to the crash. In the event of a crash or during the crash, the viscosity of the cooling liquid increases, ie the cooling liquid becomes more viscous or viscous. This increases a flow-mechanical resistance, for example a resistance counteracting displacement of the cooling liquid, which has to be overcome by the battery cell arrangement in order to be able to move through the cooling liquid. The battery cell arrangement is thus braked and/or dampened inside the housing when it is moved or accelerated in relation to the housing due to the accelerations acting on it as a result of the accident, that is to say is moved through the coolant.

Since the cooling liquid inside the battery or inside the housing acts as the damping element, which is or is only generated or stiffened as required, ie depending on an accident, the battery can be made particularly mass-efficient overall. This is because a conventional crash structure inside the housing or as part of the housing can be made lighter, since the cooling liquid at least supports or at least largely takes over the absorption of the kinetic energy generated by an accident. This provides a particularly mass-efficient battery that is particularly crash-proof. As a result, a motor vehicle equipped with the battery can be operated in a particularly mass-efficient manner and, as a result, in a particularly energy-efficient and low-emission manner.

In a possible development of the battery, the non-Newtonian coolant is at least partially rheopex. This means that the coolant is designed in such a way that its viscosity increases under continuous shearing stress. Under shear stress, the cooling liquid therefore changes from the first, lower-viscosity rheopex viscosity state to the second, higher-viscosity viscosity state. If there is no shear stress, the cooling liquid changes from the first, higher-viscosity rheopex viscosity state (again) to the second, lower-viscosity viscosity state. For this purpose, the coolant can have, for example, a solid, gaseous or liquid component that gives the coolant the rheopexy. If, for example, due to the accident, there is a shearing load to which the coolant is or will be subjected, it becomes more viscous, so that movement of the battery cell arrangement in relation to the housing (ie inside the housing) is slowed down. This effectively prevents the battery cell arrangement from being excessively damaged, in particular individual battery cells being excessively deformed, for example breaking by impacting an inner wall of the housing without braking. The risk of thermal runaway and its propagation is significantly counteracted by the battery with the non-Newtonian coolant.

According to another possible embodiment of the battery, the non-Newtonian coolant is at least partially dilatant. This means that the cooling liquid is designed in such a way that its viscosity increases as the shear load changes over time. When there is a change in shearing stress, the cooling liquid therefore changes dilatantly from the first, lower-viscosity viscosity state to the second, higher-viscosity viscosity state. If there is no change in the shearing stress, the coolant changes dilatantly (again) from the first, higher-viscosity viscosity state to the second, lower-viscosity viscosity state. For this purpose, the coolant can have, for example, a solid, gaseous or liquid component that gives the coolant the dilatancy. If there is a change in the shearing load - for example as a result of the accident - to which the coolant is or will be subjected, it becomes more viscous. For example, an accident in which the motor vehicle and consequently the battery are subjected to many different accelerations, which occur regularly or irregularly over time and/or have many changes in direction, can be the cause of the changes in shear stress. This is the case, for example, when the motor vehicle skids, rolls over, multiple impacts, a secondary accident, etc. Due to the dilatant cooling liquid, a movement of the battery cell arrangement in relation to the housing (that is, inside the housing) is slowed down in these complex accident scenarios. Even in highly complex accidents in which the motor vehicle or the battery is/is subjected to many, possibly irregular accelerations, this effectively prevents the battery cell arrangement from being damaged to such an extent that battery cells break by hitting an inner wall of the housing without braking.

According to a second aspect of the invention, the coolant of the battery is designed to flow around the battery cell arrangement in the first viscosity state with a higher viscosity (as an example of understanding: for example like water). In the first viscosity state, the cooling liquid therefore functions primarily or entirely as a conditioning liquid in order to cool and/or heat the battery cell arrangement in order to bring an operating temperature of the battery cell arrangement to an optimum level or to keep it there. The first viscosity state of the coolant is present in particular during normal operation of the battery or of the motor vehicle equipped with the battery, with the coolant being pumped through a cooling circuit at a higher viscosity at common operating temperatures and pressures in order to cool/heat the battery cell arrangement.

The cooling liquid assumes the second viscosity state, in which the cooling liquid is or becomes less viscous than the first viscosity state (ie less viscous or more fluid than water) due to a shearing load. For example, the shear stress can be applied by suitably controlling a pump pressure with which the cooling liquid is pumped through the battery. This increases the liquid pressure of the cooling liquid. Thus, the viscosity of the cooling liquid decreases when the cooling liquid is subjected to the liquid pressure increase. From the The properties of the cooling liquid mentioned result in the fact that when the liquid pressure is increased, a higher cooling liquid mass flow can be used in order to cool the battery cell arrangement. If there is an increased cooling capacity requirement compared to normal operation, the increase in liquid pressure can be used to make use of an increased coolant mass flow compared to normal operation for cooling the battery cell arrangement, although the total amount of coolant in the overall battery system remains the same. It can be provided, for example, under, before and/or after an accident, to control or regulate the pump pressure in such a way that the liquid pressure of the cooling liquid is increased in order to provide the highest possible cooling capacity for the battery cell arrangement. In this way, for example, heat released by a thermal runaway of one or more of the battery cells can be dissipated by means of the coolant, so that propagation of the thermal runaway to one or more of the other battery cells is effectively counteracted, provided a coolant circuit and an associated pump are still functional.

Furthermore, the non-Newtonian coolant supports a particularly mass-efficient design of the battery, since the viscosity of the coolant can be adjusted as required - naturally also when the motor vehicle is operated in which it is not subjected to any accident, pre- and/or post-crash measures. If, for example, there is a need for only a low cooling capacity, for example to heat the battery in order to reach a particularly preferred operating temperature for the battery or the battery cells, it can be provided that the cooling liquid is pumped with a liquid pressure in which the cooling liquid flows through the battery cell arrangement with higher viscosity. If, on the other hand, there is a need for a higher cooling capacity, for example when the battery is being charged, it can be provided that the cooling liquid is pumped at a liquid pressure in which the cooling liquid flows through the battery cell arrangement with a lower viscosity.

A cooling capacity for the battery can thus be set particularly efficiently as required, with--compared to a conventional Newtonian coolant--a lower quantity of coolant overall being required in the overall system, since the same amount of coolant mass in the overall system is required to provide the increased coolant mass flow for a greater cooling capacity to provide the lower cooling capacity. With conventional Newtonian cooling liquids, the cooling liquid mass must correspond to a maximum possible cooling performance requirement, which leads to a particularly high mass of conventional cooling liquid. The non-Newtonian coolant thus contributes to an advantageously particularly high level of crash safety and, at the same time, to a battery that is designed to be particularly mass-efficient.

According to a possible development of the battery, the non-Newtonian coolant is at least partially thixotropic. This means that the coolant is designed in such a way that its viscosity decreases under continuous shearing stress. Under shear stress, the cooling liquid therefore changes thixotropically from the first, higher-viscosity viscosity state to the second, lower-viscosity viscosity state. If there is no shearing stress, the coolant changes (again) from the second, lower-viscosity viscosity state thixotropically into the first, higher-viscosity viscosity state. For this purpose, the cooling liquid can have, for example, a solid, gaseous or liquid component which gives the cooling liquid its thixotropy. If, for example, due to the accident or due to a corresponding control of the liquid pressure, there is a shearing load to which the cooling liquid is or will be subjected, it becomes thinner so that it washes around the battery cell arrangement with a lower viscosity. On the one hand, the first and the second viscosity state of the cooling liquid can be set particularly easily. On the other hand, the heat dissipation or cooling capacity is increased as required, which counteracts unwanted overheating of the battery cells. In the event of a crash, the risk of thermal runaway and its propagation is counteracted to a large extent.

In a further embodiment of the battery, the non-Newtonian cooling liquid is at least partially pseudoplastic or pseudoplastic or shear-thinning. This means that the cooling liquid is designed in such a way that its viscosity decreases as the shear load changes over time. When there is a change in shearing stress, the cooling liquid therefore changes pseudoplastically from the first, higher-viscosity viscosity state to the second, lower-viscosity viscosity state. If there is no change in the shear stress, the cooling liquid changes pseudoplastically (again) from the second, lower-viscosity viscosity state to the first, higher-viscosity viscosity state. For this purpose, the coolant can have, for example, a solid, gaseous or liquid component that gives the coolant its pseudoplasticity or structural viscosity. If, for example, due to the accident or due to a corresponding control of the liquid pressure, there is a shearing load to which the cooling liquid is or will be subjected, it becomes thinner so that it washes around the battery cell arrangement with a lower viscosity. For example, an accident in which the motor vehicle zeug and as a result many different accelerations on the battery, which occur regularly or irregularly over time and/or have many changes in direction, can be the cause of the changes in shear stress. This is the case, for example, when the motor vehicle skids, rolls over, multiple impacts, a secondary accident, etc. Due to the pseudoplastic coolant, the battery cell arrangement inside the housing is washed around with low viscosity in these complex accident scenarios and is therefore particularly efficiently heated. This efficiently counteracts overheating of the battery cells even in highly complex accidents in which the motor vehicle or the battery is/is subjected to many, possibly irregular, accelerations.

Irrespective of whether the non-Newtonian cooling liquid in the battery has rheopexic, dilatant, thixotropic or pseudoplastic properties, a further development of the battery provides for the cooling liquid to have a heat transfer coefficient and a specific heat capacity which are dimensioned in such a way that the heat generated at a thermal runaway of at least one of the battery cells or of a predetermined number of battery cells of the battery cell arrangement is released, can be recorded so quickly and to such an extent that propagation of the thermal runaway is significantly slowed down, ideally stopped. For this purpose, the coolant can have a solid, gaseous or liquid component that gives the coolant the appropriate heat transfer coefficient and the appropriate specific heat capacity. In this way, the safety of the battery is advantageously further increased by means of the cooling liquid.

Another possible embodiment of the battery - regardless of whether the non-Newtonian coolant of the battery has rheopexic, dilatant, thixotropic or pseudoplastic properties - provides that the non-Newtonian coolant is a coolant for a motor vehicle unit that is electrically and fluidically connected to the battery acts. Accordingly, when the battery is in operation, the coolant acts both to cool the battery cell arrangement and to cool the assembly. The unit and the battery are electrically connected or can be connected to one another for the transmission of electrical energy. In addition, both the battery and the unit are integrated into a common coolant circuit. The battery, in particular its battery cell pack, and the assembly are thus cooled by means of the same cooling liquid circuit, at least by means of the same cooling liquid. Thus, several liquids do not have to be provided separately from one another in order to efficiently cool the battery and at least one other unit. This further enhances the mass saving benefit. Furthermore, the advantages of the non-Newtonian fluid for the unit, through which the coolant flows at least during operation, apply at least analogously: crash safety is advantageously particularly high if the non-Newtonian fluid is used to dampen a component in a unit housing with regard to its acceleration caused by an accident. Alternatively or additionally, cooling of the corresponding component can be adjusted as required.

• - ein Kühlkreislauf einer Verbrennungskraftmaschine,
• - ein Kältemittelkreislauf einer Innenraumklimatisierungseinrichtung,
• - ein Kühlkreislauf einer elektrischen Invertervorrichtung.

The unit is in particular an electromechanical converter, such as a traction motor, which is designed to convert electrical energy provided by the battery into kinetic energy for moving the motor vehicle. During operation, the cooling liquid can flow through a rotor chamber of the traction motor, which means that the rotor chamber is integrated into the cooling liquid circuit of the battery or is fluidly connected to it. Other examples of the aggregate are (not exhaustive):

• - a cooling circuit of an internal combustion engine,
• - a refrigerant circuit of an interior air conditioning device,
• - a cooling circuit of an electric inverter device.

The invention also relates to a method for operating a battery designed according to the above description. In this case, a battery cell arrangement of the battery is flowed around by the non-Newtonian cooling liquid which, due to the shearing stress, tends to move from the first viscosity state to the second viscosity state. The first viscosity state characterizes a viscosity of the cooling liquid that differs from another viscosity of the cooling liquid that is characterized by the second viscosity state.

The invention also relates to a motor vehicle that has a battery designed in accordance with the above description. The motor vehicle is an at least partially electrically driven passenger car and/or truck or a motorcycle.

Further features of the invention can result from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description as well as those in the figures below Features and feature combinations shown alone in the description and/or in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the invention.

• 1 eine schematische Seitenansicht eines Kraftfahrzeugs, das eine Batterie mit einer nichtnewtonschen Kühlflüssigkeit aufweist;
• 2 zur Verdeutlichung der nichtnewtonschen Eigenschaften der Kühlflüssigkeit ein erstes Diagramm; und
• 3 zur Verdeutlichung der nichtnewtonschen Eigenschaften der Kühlflüssigkeit ein zweites Diagramm.

The drawing shows in:

• 1 a schematic side view of a motor vehicle having a battery with a non-Newtonian coolant;
• 2 a first diagram to illustrate the non-Newtonian properties of the coolant; and
• 3 a second diagram to illustrate the non-Newtonian properties of the coolant.

In the figures, identical and functionally identical elements are provided with the same reference symbols. A battery 1, 2 and a motor vehicle 3 having the battery 1, 2 as well as a method for operating the battery 1, 2 are presented in a joint description below.

For this shows 1 a schematic side view of a motor vehicle 3, which has a battery 1, 2 with a non-Newtonian cooling liquid 4. The battery 1, 2 comprises a housing 5 in which a battery cell arrangement 6, which is formed from a large number of battery cells 7, is arranged. When the battery 1, 2 is in operation, the coolant 4 flows directly around the battery cells 7. This in 1 Motor vehicle shown also has a unit 8, which is electrically and fluidly coupled or connected to the battery 1, 2, whereby the cooling liquid 4 during operation of the battery, in particular during operation of the motor vehicle 3, both the battery 1, 2 and the unit 8 flows through. In the present example, the unit 8 is a traction motor 9 of the motor vehicle 3. The cooling liquid 4 is therefore the cooling liquid of the battery 1, 2 and the cooling liquid of the unit 8, in this case the traction motor 9.

The cooling liquid 4 has a heat transfer coefficient and a specific heat capacity that are dimensioned such that heat that is released during a thermal runaway of battery cells 7 of the battery cell arrangement 6 can be absorbed so quickly and to such an extent that the thermal runaway propagates is stopped. In other words, the cooling liquid 4 is provided, that is selected or manufactured or mixed, in such a way that it has the heat transfer coefficient and the specific heat capacity that are required to absorb enough heat quickly enough so that the thermal runaway is at least significantly slowed down, in particular completely is stopped.

Because of a shearing load, the coolant 4 moves from a first viscosity state into a second viscosity state. The first viscosity state characterizes a viscosity of the cooling liquid 4 which differs from another viscosity of the cooling liquid 4 characterized by the second viscosity state. Based on the first viscosity state, which can represent a state of rest of the cooling liquid 4, the viscosity of the cooling liquid 4 in the second viscosity state is higher or lower. Since the cooling liquid 4 is a non-Newtonian fluid, the transition between the viscosity states or the tendency towards or into the respective viscosity state takes place based on a non-linear relationship between a shear stress τ and a shear rate γ̇.

In the present case, the non-Newtonian cooling liquid 4 of the battery 1 has a lower viscosity in the first viscosity state than in the second viscosity state. As a result, the low-viscosity cooling liquid having the first viscosity state washes around the battery cell arrangement 6 . For example, due to an accident in which the battery 1 having the motor vehicle 3 is involved, the cooling liquid 4 experiences a shearing load, as a result of which the cooling liquid 4 tends to the second viscosity state, in particular assumes the second viscosity state, with the viscosity of the cooling liquid 4 increasing. The cooling liquid 4 thus becomes more viscous under the influence of the shearing stress. As a result, the cooling liquid 4 in the housing 5 forms a damping element 10 for the battery cell arrangement 6. A movement of the same within the housing 5 is thereby at least dampened or braked. For this purpose, the coolant 4 in the present case is at least partially rheopex and/or at least partially dilatant.

In the present case, the non-Newtonian cooling liquid 4 of the battery 2 has a higher viscosity in the first viscosity state than in the second viscosity state. As a result, the coolant, which has the first viscosity state, flows around the battery cell arrangement 6 in a highly viscous manner. For example, due to an accident in which the motor vehicle 3 having the battery 2 is involved, the cooling liquid 4 experiences a shearing load, as a result of which the cooling liquid 4 tends to the second viscosity state, in particular assumes the second viscosity state. Furthermore provided that the cooling liquid 4 can be loaded with shear by a pump, by means of which the cooling liquid 4 is pumped to flow around the battery cell arrangement 6 or can be controlled or regulated. In any case, the viscosity of the cooling liquid 4 decreases with the shearing load. The cooling liquid 4 thus becomes thinner under the influence of the shearing stress. As a result, the coolant 4 in the housing 5 flows around the battery cell arrangement 6 with a lower viscosity, as a result of which a lower viscosity forms a higher coolant mass flow for the same coolant volume and increased coolant pressure. During a specific time interval, more of the cooling liquid 4 in the second viscosity state flows past locations of the battery 2 to be cooled than the cooling liquid 4 in the first viscosity state would flow past during the same time interval. As a result, a particularly efficient heat dissipation at the points of the battery 2 to be cooled is achieved as required. For this purpose, the coolant 4 in the present case is at least partially thixotropic and/or at least partially pseudoplastic.

To illustrate the non-Newtonian properties of the cooling liquid 4 is on the 2 and on the 3 referenced, which show a respective diagram. In the diagram of 2 a relationship between the shear stress τ and the shear rate γ̇ is shown. For comparison, line 11 represents a linear relationship between the shear stress τ and the shear rate γ̇ of a Newtonian fluid, for example pure water. Line 12 represents the non-linear shear stress-shear rate relationship of a dilatant fluid, such as cooling liquid 4, or a component of cooling liquid 4, whose viscosity increases under sustained shear stress change. Line 13 characterizes a further non-linear shear stress-shear rate relationship, namely that of a structure-thinning or pseudoplastic fluid, for example the cooling liquid 4, or a component of the cooling liquid 4, the viscosity of which decreases as the shear stress changes over time.

In the diagram of 3 a relationship between the viscosity η and a duration t during which the shear stress τ acts on the respective fluid is shown. Line 14 represents the non-linear relationship between the shear stress τ acting over the duration t and the viscosity η of a rheopexic fluid, for example the cooling liquid 4, or a component of the cooling liquid 4, the viscosity of which increases under sustained shear stress. Line 15 characterizes another non-linear relationship between the shear stress τ acting over the duration t and the viscosity η, namely that of a thixotropic fluid, for example the cooling liquid 4, or a component of the cooling liquid 4, the viscosity of which decreases under sustained shear stress τ.

The battery 1, 2, the motor vehicle 3 and the method show a respective possibility of creating a particularly crash-safe electrically driven motor vehicle that is also particularly light and can be operated particularly energy-efficiently and with low emissions. Conventional, heavy and space-consuming components or structures for protecting a conventional battery or a conventional high-voltage storage device from damage can be made lighter or at least partially eliminated due to the present invention. In the event of a crash or fault, the coolant is used as intended for the physical and thermal protection of the battery cells 7 and their periphery. A thermal event, especially a runaway, can be efficiently delayed or stopped completely. This leads to a particularly advantageous level of safety for the occupants of the motor vehicle 3. In addition, a cooling capacity can be adjusted as required by increasing the coolant mass flow for the same volume.

Reference List

1

battery

2

battery

3

motor vehicle

4

coolant

5

Housing

6

battery cell assembly

7

battery cell

8th

aggregate

9

traction engine

10

damping element

11

line

12

line

13

line

14

line

15

line

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102014218023 A1 [0005]

Claims (10)

Battery (1) for an electrically drivable motor vehicle (3), with a housing (5) and a battery cell arrangement (6) arranged in the housing (5) and with a non-Newtonian cooling liquid (4), from which the battery cell arrangement (6) flows around the battery (1) during operation, the cooling liquid (4) being designed to - To flow around the battery cell arrangement (6) in a first viscosity state of lower viscosity and - In a second viscosity state, in which the cooling liquid (4) is or becomes more viscous than in the first viscosity state due to shear stress, to form a damping element (10) in the housing (5) for the battery cell arrangement (6). battery (1) after claim 1 , characterized in that the cooling liquid (4) is designed in such a way that its viscosity increases under continuous shearing stress. battery (1) after claim 1 or 2 , characterized in that the cooling liquid (4) is designed in such a way that its viscosity increases under constant shear stress change. Battery (2) for an electrically drivable motor vehicle (3), with a housing (5) and a battery cell arrangement (6) arranged in the housing (5) and with a non-Newtonian cooling liquid (4), from which the battery cell arrangement (6) flows around the battery (2) during operation, the cooling liquid (4) being designed in such a way - To wash around the battery cell arrangement (6) in a first viscosity state of higher viscosity and - In a second viscosity state, in which the cooling liquid (4) is or becomes less viscous than in the first viscosity state due to shear stress, to flow around the battery cell arrangement (6). battery (2) after claim 4 , characterized in that the cooling liquid (4) is designed in such a way that its viscosity decreases under continuous shearing stress. battery (2) after claim 4 or 5 , characterized in that the cooling liquid is designed in such a way that its viscosity decreases under continuous shear stress changes. Battery (1, 2) according to one of the preceding claims, characterized in that the cooling liquid (4) has a heat transfer coefficient and a specific heat capacity which are dimensioned such that heat which occurs in the event of a thermal runaway of battery cells (7) of the battery cell arrangement ( 6) becomes free can be ingested so rapidly and to such an extent that propagation of thermal runaway is stopped. Battery (1, 2) according to one of the preceding claims, characterized in that the non-Newtonian cooling liquid (4) is a cooling liquid (4) for a unit (8) electrically and fluidically connected to the battery (1, 2) of the Motor vehicle (3) is. Method for operating a battery (1, 2) designed according to one of the preceding claims, wherein a battery cell arrangement (6) of the battery (1, 2) is flowed around by a non-Newtonian cooling liquid (4) which, due to a shearing load, changes from a first viscosity state to a seeks a second viscosity state, each characterizing a different viscosity of the cooling liquid (4). Motor vehicle (3) with one after one Claims 1 until 8th trained battery (1, 2).

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