DE102021124831A1 - Battery assembly and motor vehicle - Google Patents

Abstract

The invention relates to a battery arrangement (1) for a motor vehicle with a large number of battery and deformation elements (20, 30) which together form a stacked assembly (11). The stacked assembly (11) is arranged in a battery housing (12) of the battery arrangement (1). The battery elements (20) are mounted in the stacked assembly (11) so that they can be displaced in a predetermined stacking direction (R). In the event that at least one of the battery elements (20) in the stacked assembly (11) now has a predetermined heating state (Z), the respective deformation element (30) adjoining the stacked assembly (11) is designed to have an increase in volume by in a first preventive state provide a predetermined limit amount and thereby bring about at least one displacement of the remaining battery elements (20) in the battery housing (12).

Description

The invention relates to a battery arrangement for a motor vehicle with a large number of battery elements and deformation elements which together form a stacked assembly. The stacked assembly is arranged in a battery housing of the battery arrangement. In the stacked assembly, at least one of the deformation elements is arranged in a thermally contacting manner between two battery elements arranged adjacent to one another at a predetermined distance. In this case, the respective deformation element is formed from a deformable enveloping medium filled with a fluid.

In an electrically drivable motor vehicle, such as an electric or hybrid vehicle, a battery arrangement can be used as an electrical energy store for operating an electric drive of the motor vehicle. The battery arrangement can be a traction battery or a high-voltage battery, for example. The battery arrangement can be designed, for example, as a secondary battery or accumulator and can thus be charged or discharged for the operation of the motor vehicle. In order to be able to provide electrical energy for operating the motor vehicle, the battery arrangement can comprise a plurality of battery elements which are electrically connected to one another in a suitable manner. Such a battery element can be a battery cell, for example. A battery element uses chemical reactions of an active material to generate electrical energy. Different technologies or compositions of the active material are known for battery elements. Battery elements with different technologies are, for example, so-called lithium-ion cells or lithium-iron phosphate cells or solid cells. Different types are also known for a shaped body of a battery element, ie a packaging of the active material in a desired cell shape. For example, prismatic or round or cylindrical or so-called pouch cells can be used.

Two different options for arranging the battery elements in a battery housing are known for forming the traction battery. According to a first option, the individual battery elements can first be installed in a so-called cell module or battery module in a common module housing. A plurality of such battery modules can then in turn be connected to one another in a suitable electrical manner to form the drive battery and can be arranged in the battery housing. According to a second option, the individual battery elements can be introduced directly into the battery housing, for example. The battery arrangement mentioned can thus be, for example, a battery module or the entire drive battery.

The battery elements are stacked in order to arrange the battery elements in the housing, that is to say to pack the battery elements. This means that the cells are arranged next to one another or adjacent to one another in a form adapted to the battery housing and then introduced into the battery housing. The battery elements thus form a battery assembly or battery stack. Here, the prismatic cell shape can be preferred. Because in the case of prismatic cells, stacking can take place, for example, by always placing the battery elements against one another with the largest side surface in each case.

An example of a method for arranging or stacking battery cells arranged in a row is about from DE 35 29 727 A1 known. The accumulator cells should be clamped in the battery housing to prevent them from slipping. For this purpose, air cushions are introduced between the accumulator cells, so that the accumulator cells are pressed against the housing wall in the stacking direction when the air cushions are inflated. The accumulator cells are then finally clamped in the battery housing with wedges so that they cannot slip and the air can be released from the air cushions.

Experiments have shown that bracing the battery elements can help to improve the service life and function of the battery arrangement. Because the battery elements can experience a change in volume during normal operation and with increasing aging due to the electrochemical processes. This process is called swelling or cell breathing. During bracing, the battery elements in the battery stack are each held in the battery housing with a predetermined compressive force with respect to one another and the housing. The unchecked increase in volume is thereby avoided. The compression force should be kept as constant as possible over the entire service life of the battery arrangement. In order to achieve this, so-called cell separator elements can be introduced into the battery stack. In this case, for example, one or more such cell separating elements can be arranged in each case between two adjacent battery elements. The cell separators form spacers and buffers between the battery elements. Together with the cell separators, the battery elements form a stacked assembly.

The use of cell separators as compression pads between adjacent batte ry cells in a traction battery, for example DE 10 2019 128 433 B3 known. The compression cushions can be elastic elements, for example, or they can be designed to be as stiff and unyielding as possible. In this case, the compression cushions are used in particular to support a cooling channel system, which can also be arranged between the battery elements.

In order to counteract the effects of swelling for an accumulator, it is also necessary to DE 10 2012 224 330 A1 a stacked composite of accumulator cells and elastic deformation elements known as cell separators. The elastic elements can be, for example, a gas-filled cushion or an airbag. The cushion thereby provides a closed, sealed structure made of an elastically deformable material for confining the gas.

Another function of a cell separator can be to thermally shield the battery elements from one another. For this purpose, for example, a rigid or solid molded body can be used as the cell separating element. So-called mica plates, for example, are used for this function. So-called mica or a ceramic material, for example, is suitable as a material. However, this results in the disadvantage that with increasing energy content or increasing capacity of the battery elements for the thermal shielding, the thickness of the cell separator elements must also be increased. As a result, a distance between the individual battery elements in the stacked assembly is also increased. As the energy content increases, fewer battery elements can be installed in the available installation space or in the battery housing. Overall, less powerful drive batteries can be produced in this way, which, for example, limits a range or vehicle performance (vehicle performance).

It is the object of the present invention to provide thermal insulation of battery elements in a battery assembly for a motor vehicle, which enables improved vehicle performance.

The object is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are disclosed by the dependent patent claims, the description and the figures.

In order to achieve or effect improved vehicle performance, a battery assembly for a motor vehicle is disclosed in the invention. The battery arrangement comprises a large number of battery and deformation elements which together form a stacked assembly. The stacked assembly is arranged in a battery housing of the battery arrangement. In the stacked assembly, at least one of the deformation elements is arranged in a thermally contacting manner between two adjacent battery elements, ie arranged adjacent to one another at a predetermined distance. The respective deformation element thus serves as a spacer between two adjacent battery elements. In the present case, “thermally contacting” means that thermal energy or thermal energy can be released from the battery element directly, that is to say essentially without an intermediate medium, to the deformation element. In order to ensure the thermal contact, the respective deformation element can rest directly with a respective contact side on a facing contact side of the battery element in a stacking direction predetermined by the stack assembly. The contact sides can, for example, touch each other completely or at least in sections. For example, each battery element can be pressed or compressed between two deformation elements. Analogously, each deformation element can be pressed or arranged in a compressed manner between two battery elements, for example.

According to the invention, the respective deformation element is designed to be deformable. That is, the deformation element can comprise an elastic or plastic material. It is provided here that the respective deformation element is formed from a deformable enveloping medium filled with a fluid. The envelope medium can thus form an outer envelope for the fluid. That is, the containment medium can be a closed, sealed structure made of an elastically or plastically deformable material that can form a cavity when filled with the fluid. The fluid can be a gas or a liquid, for example. The gas may include air or nitrogen or oxygen, for example.

In the stacked composite, the deformation elements have a predetermined internal pressure in a normal state or basic state. This means that the fluid pressure of the fluid inside the enclosing medium can be within a predetermined range of values. This can be preset, for example, in a manufacturing process for the supply elements or set in an assembly process when forming the stacked assembly by compressing the stacked assembly. In the assembly process, the stacked composite can be compressed, for example, with a force of around 2 to 8 kN. With normal state or basic state is meant here, for example, a state that the deformation elements in the intended operation of the battery assembly as electrical energy storage have cher of the motor vehicle. It can therefore be a state directly after the manufacturing process or the assembly process, which can be maintained, for example without defects in the battery elements, until the end of life or use of the battery elements. The internal pressure can be in a value range from 0.1 to 0.4 pascal, for example.

In addition, the battery elements and, for example, also the deformation elements are mounted in the battery housing such that they can be displaced in the specified stacking direction. This means that the battery elements can be moved or shifted relative to the battery housing, for example laterally, ie along the specified stacking direction. In this case, for example, the entire stacked assembly can be displaced in the battery housing, or the battery elements can be displaced relative to the stacked assembly. In the first case, an increase in volume of the stacked composite can thus be brought about. In the second case, a volume of the composite stack can be kept constant, for example.

In the event that at least one of the battery elements in the stacked assembly now has a predetermined heating state, it is provided that the deformation element that is adjacent in the stacked assembly, i.e. the thermally contacting deformation element, is designed to provide an increase in volume by a predetermined limit amount in a first preventive state. Due to the increase in volume, the deformation element is designed to bring about at least a displacement of the remaining battery elements in the battery housing. In the present case, the remaining battery elements are those battery elements which are not in the heating state. For example, battery elements can be involved which, in contrast to the heating state, have a specified operating state.

The increase in volume can also increase the distance between the adjacent battery elements. In other words, the deformation elements can change between the normal state and the first prevention state. Namely, depending on whether the adjacent, ie thermally contacted, battery element is in the heating state or not.

The heating condition relates to, for example, overheating or thermal runaway of the battery element. In the heated state, the battery element has a temperature in a predetermined temperature value range. The range of temperature values can be between 80° and 1,200° Celsius, for example. By heating the battery element to the heating state and on, the adjacent deformation element is also heated. As a result, the fluid can have, for example, an average temperature which lies within the predetermined temperature value range and which is attributable to a thermal runaway of the battery element with which the deformation element is in thermal contact. The heating state is thus different from the intended operating state. The heating condition can occur, for example, in the event of a defect such as a short circuit or contamination.

The increase in volume and the resulting increase in distance between the undamaged or intact battery elements (in the intended operating state) results in the advantage that thermal insulation between the battery elements can be improved. In this way, the heating condition can be effectively prevented from spreading from one battery element to the other. In this way, for example, a battery fire can be avoided or at least delayed. The increase in volume can thus serve to prevent the spread of heat. It can thereby be avoided that, if one of the battery elements thermally runs away, the remaining battery elements in the stacked assembly follow in a chain reaction or are entrained.

The property of a fluid to expand when heated is used to provide the increase in volume. The increase in volume usually does not occur suddenly. Instead, the volume of the respective deformation element can increase slowly or continuously with increasing temperature until the desired increase in volume is achieved when the heating state is present. An amount of volume increase depends, for example, on a coefficient of thermal conductivity or coefficient of expansion of the particular material comprising the fluid.

As described above, the fluid can be present in various configurations, namely, for example, as a gas or as a liquid. For example, the containment medium can be completely or partially filled or filled with the fluid. When using a liquid, the deformation elements are in particular incompressible. This means that when the heating state is present, essentially only an increase in volume and no reduction in volume of the deformation element can be brought about. Alternatively, the fluid can be in the form of a gas. In this case, however, when using gas, the deformation elements can be compressible, for example. That is, dependent Depending on the heating state, both an increase in volume and a reduction in volume of the deformation elements can be possible. This will be discussed in more detail later.

Instead of being purely gaseous or purely liquid, the fluid can, for example, comprise different fluid components or materials. For example, one fluid component may be in gaseous form while another is in liquid form. For example, a first sub-volume of the containment medium may comprise a liquid and a second sub-volume may comprise a gas.

The fluid can comprise, for example, water and/or air as a material or substance. If, for example, water is used as the fluid, when the boiling point of water is exceeded, for example at 100° Celsius, water vapor can also be produced as a gas, which increases the increase in volume.

In the stacked assembly, an additional deformation element can be provided in the stacking direction between a battery element lying on the outside in the stacked assembly and an adjoining housing wall of the battery housing. As a result, the battery elements on the outside in the stacked assembly can also be protected against the housing, ie a force that acts between the housing and the battery element on the outside.

The invention also includes embodiments that result in additional advantages.

In one embodiment, the fluid is a gas. The gas may include air and/or nitrogen and/or oxygen, for example. When the heating state occurs or is present, according to the embodiment, the remaining deformation elements in the stacked assembly are designed to provide a volume reduction in a second prevention state depending on the respective increase in volume of the respective adjacent deformation element. As a result, the multiplicity of deformation elements is designed to bring about a displacement of the battery elements in the stacked assembly as a result of the increase in volume and the reduction in volume. This means that the battery elements move relative to the stacked assembly. A stack volume of the stacked assembly remains the same.

In other words, the deformation element or elements that are adjacent to the battery element for which the heating condition exists exhibits the volume increase. As a result, a distance to the adjacent battery elements is increased. On the other hand, the other deformation elements, that is to say those which are adjacent to the battery elements for which the operating state is present, are compressed. The result is the reduction in volume. This brings about a reduction in the distance between the remaining battery elements.

This results in the advantage that a maximum distance can be achieved between battery elements that have not passed through and the battery element that has passed through in each case, without additional installation space being required for the stacked assembly.

The volume reduction in the second state of prevention is mainly due to two effects. On the one hand on the increase in volume of the deformation elements in the first state of prevention and on the other hand on a force between the housing and the composite stack. Namely, the stacked composite can be clamped or fitted in the battery case for a stable hold. The housing is essentially non-deformable. That is, a housing volume of the battery housing remains substantially the same and can withstand a force that acts between the stacked assembly and a housing wall of the battery housing when the deformation elements increase in volume in the first prevention state. The gas inside the remaining deformation elements can be compressed and the volume reduction of the deformation elements occurs in the second prevention state. The compression can also be promoted by the fact that the remaining deformation elements are in a colder environment than the deformation elements that are arranged on the battery element in the heating state.

According to a further embodiment, the deformation elements each have at least one valve element for providing or adjusting a mass flow of the gas out of the enveloping medium. In the context of the present invention, a valve element generally means a component for fluidic connection between two separate volumes. For this purpose, the valve element can be adjusted or moved at least between two positions. In an open position, mass flow is permitted or enabled. In a closed position, mass flow is prevented or blocked.

In the present embodiment, the respective valve element thus serves to fluidically connect the envelope volume and the environment, ie, for example, the interior of the battery housing. According to the embodiment, two different variants are conceivable for the configuration of the valve element.

In a first variant of the embodiment, the valve element is designed to provide or set the mass flow to a valve body of the respective valve element as a function of a predetermined pressure value of the gas. The pressure value is specified as a function of the volume reduction. This means that the valve element only changes to the open position if the pressure inside the enveloping medium exceeds a predetermined pressure limit value. The gas can thus escape from the enveloping medium into the environment, for example into the battery housing. The valve element can be said to be pressure controlled and open or close automatically. Automatic means that the valve element can be adjusted without additional control electronics. The valve element can thus be a pressure compensation valve, for example.

In a second variant of the embodiment, the battery arrangement additionally or alternatively comprises a monitoring device which is designed to detect the heating state and/or the reduction in volume and then a control signal for controlling an actuator of the valve elements of the remaining deformation elements, i.e. the deformation elements in the second prevention state. provide and thereby cause the mass flow. The closing of the valve element can be electronically or electrically controlled depending on the monitoring.

To monitor the stacked assembly, the monitoring device can have a sensor unit, for example. In order to detect or detect the heating state, the sensor unit can have a temperature sensor, for example, which monitors the temperature of the respective battery element. For this purpose, at least one separate or dedicated temperature sensor can be assigned to each battery element, for example. Alternatively, a common temperature sensor can be provided for the stacked assembly. In order to determine or establish the reduction in volume, the sensor unit can have a pressure sensor or a length sensor, for example. The pressure sensor can be used, for example, to measure a pressure of the gas, that is to say an internal pressure in the enveloping medium. The length sensor can be used, for example, to measure the change in distance between the adjacent battery elements, which is caused by the reduction in volume and acts in the stacking direction. The respective monitoring value or sensor value of the sensor unit can then be made available, for example, to an evaluation unit of the monitoring device for evaluating and generating the control signal. For this purpose, the evaluation unit can have a control device, such as a microcontroller, for example. The evaluation unit can be used to compare the respective monitoring value with a corresponding limit value for evaluation. If the limit value is either fallen below or exceeded, depending on the configuration of the monitoring value, the control signal can be generated and the actuator can be controlled with it.

This results in the advantage that when the volume elements are compressed in the second prevention state, stability of the enveloping medium can be ensured. The reduction in volume, ie the compression, increases the pressure of the gas inside the enveloping medium. In order to protect the deformation element from damage due to the pressure increase, the corresponding valve element can be used.

According to a further embodiment, the fluid is a liquid and the deformation elements each have at least one valve element for providing or adjusting a mass flow of the liquid out of the enveloping medium. The battery arrangement also includes a monitoring device that is designed to detect the heating state and then provide a control signal for controlling an actuator of those valve elements of the other deformation elements in the second preventive state, i.e. those deformation elements that are not adjacent to the battery element that is in the heating state. As a result, the monitoring device is designed to bring about the mass flow. This results in the advantage that the volume reduction of the deformation elements in the second prevention state can also be realized for the liquid-filled enveloping medium. A displacement of the battery elements relative to the stacked assembly is possible and a reduced space requirement for the stacked assembly can be reconciled with the thermal insulation.

The valve element can be, for example, the electronically controllable valve element described above. Reference can also be made to the design options described above with regard to the monitoring device.

The following embodiments deal with how the enclosing medium can be designed.

For this purpose it is provided in one embodiment that the enveloping medium has at least one material which is designed to be temperature-resistant at least for the presence of the heating criterion. This means that the encasing medium can, for example, have a melting point that is greater than the range of temperature values that occurs at the point of heating condition is present. It can thus be ensured that the increase or decrease in volume can be realized by the respective deformation element without the enveloping medium being destroyed or losing its tightness during deformation or heating.

Materials that may be suitable for the containment medium are disclosed in another embodiment. According to a first variant, the enveloping medium has a metallic material comprising steel or aluminum. The enclosing medium can thus be shaped or formed from a metal sheet or a plate, for example. A thickness or strength of the metallic material can be adapted, for example, to the temperature range that is present for the heating state.

According to a second variant, the enveloping medium can have a fiber-reinforced plastic, the plastic comprising aramid or glass or carbon as a fiber-reinforced material. Polytetrafluoroethylene (PTFE), for example, is a suitable plastic. The fiber-reinforcing material can thus be incorporated into the plastic. For example, a ratio between the plastic and the fiber reinforcement can be adjusted to a desired temperature range. For example, Kevlar fibers, glass fibers or carbon fibers such as plastic nanotubes (carbon nanotubes) can be used for the fiber reinforcement.

In a third variant, the enveloping medium has a fiber composite material. The fiber composite material is coated with a coating material which is designed to be temperature-resistant at least for the presence of the heating state. The enveloping medium can thus be multi-layered. For example, a fiber composite material, ie a material that is not temperature or heat resistant in the desired temperature range, can be selected for a main material of the enveloping medium. This material can then be coated with a temperature resistant material. For example, a natural fiber or a synthetic fiber can be selected for the fiber composite material. In order to ensure the temperature resistance of the enveloping medium, both an inside and an outside of the enveloping medium can be coated with the coating material, for example.

The following embodiments deal with how an electrical contacting unit can be implemented that allows the battery elements to be displaced in the battery housing.

For this purpose, one embodiment provides for an electrical contacting unit to be provided for electrical contacting of the battery elements. The contacting unit can, for example, have a printed circuit board with conductor tracks and connection contacts. As a result, for example, electrical contacting of the battery elements with one another or with one another and/or with an on-board network of the motor vehicle can be made possible. The contacting unit is arranged at least in sections on a surface of the stacked assembly lying in the stacking direction. This means that the contacting unit can rest, for example, on a respective side surface of the battery elements and/or the deformation elements. In this case, it can be advantageous if that surface of the stacked assembly is selected for the surface for arranging the contacting unit, on which electrical connection poles or connection contacts are designed for the battery elements.

At least one flexible conductor section is provided for connecting the battery elements to the contacting unit. This can form the connection contact of the contacting unit. This is designed to switch between a compressed state and a stretched state depending on the displacement of the battery elements. Flexible means that the conductor section can be deformed plastically or elastically.

For the purpose of contacting, the conductor section can be electrically conductively connected, for example, at one end to the respective battery element and at another opposite end to the contacting unit. Of course, a separate conductor section can be provided, for example, for each connection contact or connection pole (positive pole, negative pole) of the respective battery element. By changing between the compressed and the stretched state, a distance between the connection contacts of the respective battery element and the contacting unit can be increased or decreased depending on the displacement by means of the conductor section. A jumper wire or conductor wire, for example, can be suitable as the conductor section. In the compressed state, this can be wound up or folded, for example, and in contrast to this, in the stretched state, the winding or fold can be unfolded until an essentially completely straight conductor section is reached.

As an alternative to this, according to a further embodiment, an electrical contacting unit is provided which, as described above, is arranged in sections along a surface of the stacked assembly lying in the stacking direction. Instead of the flexible conductor section has the Contacting unit for each of the battery elements for electrical connection to the contacting unit on a respective busbar. This extends along the stacking direction over a predetermined section.

The busbar can essentially be a flat connection contact whose dimensions in the stacking direction are larger than the dimensions of the respective connection pole of a battery element. As a result, the busbar can provide a sliding contact for the respective battery element, for example. For electrical contact, the battery elements can slide during the displacement along the section over which the conductor rail extends and at the same time remain in electrical contact. If the battery elements are electrically connected in parallel, a common busbar can be provided for a number of battery elements, for example.

Corresponding to the flexible contacting unit, a flexible cooling unit, for example, which can be used to cool the battery elements, can be provided additionally or alternatively. For this purpose, according to one aspect of the invention, a cooling unit is provided for cooling the battery elements, the heat sink of which is arranged at least in sections along a surface of the stacked assembly lying in the stacking direction. The heat sink can, for example, be a cooling plate with an integrated cooling channel through which a coolant can flow. For example, a surface of the stacked assembly that lies opposite the surface for attaching the contacting unit can be selected for the surface for arranging the heat sink. In a predetermined installation position of the battery arrangement, the contacting unit can be arranged, for example, above the stacked assembly and the heat sink, for example, below the stacked assembly.

The cooling unit has a thermal contact layer for thermally coupling the battery elements to the heat sink. This can have a material with a predetermined thermal conductivity, for example. The thermal contact layer can be implemented, for example, by means of a thermally conductive paste or a thermally conductive pad. Overall, the battery elements can be flexibly thermally contacted with the cooling unit, even if they are moved from their original position to a different position in the battery housing or in the cell stack.

According to a further embodiment, the deformation elements are designed to deform as a function of a deformation of the battery elements caused by aging or operation. Two functions can thus be implemented by the deformation elements, namely the compression caused by aging or operation and the thermal shielding. Deformations caused by aging or operation mean, for example, the swelling described at the beginning or of the battery elements. The deformation of the battery elements during swelling, for example, can only take place locally and can be absorbed by the respectively adjacent deformation element. In this case, therefore, there is no need to shift the battery elements in the battery housing. This means that in the intended operating state, the respective deformation element can be used like a conventional cell separating element.

The invention also relates to a motor vehicle with a corresponding battery arrangement as described above. The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

The invention also includes the combinations of features of the described embodiments. The invention also includes implementations that each have a combination of the features of several of the described embodiments, unless the embodiments were described as mutually exclusive.

• 1 eine schematische Darstellung einer Batterieanordnung mit einer Vielzahl von Batterieelementen und Verformungselementen, die gemeinsam einen Stapelverbund bilden; und
• 2 eine schematische Darstellung der Batterieanordnung gemäß 1, bei der eines der Batterieelemente einen vorgegebenen Erhitzungszustand aufweist.

Exemplary embodiments of the invention are described below. For this shows:

• 1 a schematic representation of a battery arrangement with a plurality of battery elements and deformation elements, which together form a stacked assembly; and
• 2 a schematic representation of the battery arrangement according to FIG 1 , wherein one of the battery elements has a predetermined heating condition.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another and that each also develop the invention independently of one another. Therefore, the disclosure is also intended to encompass combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments are also due to further already described features of the invention can be supplemented.

In the figures, the same reference symbols designate elements with the same function.

1 1 shows a schematic representation of a battery arrangement 1. The battery arrangement 1 can be used, for example, as an electrical energy store for an electrically operated motor vehicle, ie an electric vehicle or hybrid vehicle. This means that the battery arrangement 1 can be a drive battery 10 in the present case, for example. In this case, the drive battery 10 is present, for example, as an accumulator or a secondary battery. In 1 the drive battery 10 is shown as an example in an installation position from a lateral sectional view.

The drive battery 10 includes, as in 1 shown, a housing 12 forming a battery housing, and according to FIG 1 has a rectangular cross section. Two battery poles are arranged or led out as connection poles 13 on the housing 12 as electrical contacts. In the installation position shown, the connection poles 13 are attached to an upper side of the housing. The poles 13 can form a positive pole and a negative pole of the traction battery 10, for example. An on-board network of the motor vehicle can be connected in an electrically conductive manner to the connection poles 13 in order to be supplied with electrical energy in this way.

In order to provide the electrical energy, the drive battery 10 comprises a multiplicity of battery elements 20. In 1 five such battery elements 20 are shown as an example. Of course, the drive battery 10 can have more or fewer such battery elements 20 depending on the desired amount of energy or capacity to be provided. The battery elements 20 are shown here in a prismatic shape and thus also have a rectangular cross section. Of course, other shapes, for example a round shape or a pouch shape, are also conceivable for the battery elements 20 . A battery element as in 1 is shown may be referred to as a battery cell, for example. Depending on a technology used to form the battery element 20 , each of the battery elements 20 can now provide part of the total electrical energy of the traction battery 10 . For this purpose, the respective battery element 20 comprises an active material, by means of which electrical energy and vice versa can be generated by chemical reactions. Depending on the active material used, different battery technologies are used. Here, for example, a lithium-ion technology or a lithium-iron phosphate technology can be used to form the battery elements 20 .

For an optimal service life and functionality of such a battery element, it has proven to be advantageous if a predetermined compression force is exerted on the battery element 20 from the outside, ie from an environment, over the period of use. During use, that is to say during operation, so-called swelling can occur and this can lead to an increase in the volume of the respective battery element 20 . These are brought about, for example, by the chemical reactions of the active material and irreversible chemical processes in the active material.

So-called cell separator elements can be used to implement this compression force when installing the battery elements 20 in a drive battery 10 . In 1 the cell separating elements are designed as deformation elements 30 . The battery elements 20 and the deformation elements 30 are arranged together in what is known as a stacked assembly 11 and are inserted into the battery housing 12 . In the stacked assembly 11 , at least one of the deformation elements 30 is arranged in a thermally contacting manner between two battery elements 20 arranged adjacent to one another. In the present exemplary embodiment, exactly one deformation element 30 is arranged between two adjacent battery elements 20 in the stacked assembly 11 . The deformation elements 30 are according to 1 cushion-shaped and have an elliptical cross-section.

For thermally conductive contacting, each of the deformation elements is arranged at least in sections or in areas with a respective first side directly adjacent to a second side of the respective battery element 20 . With an opposite, second side, the respective deformation element 30 is arranged directly adjacent to a first side of an opposite or adjacent battery element 20, at least in sections or in regions. This means that the respective deformation element 30 rests partially or completely on two opposite sides of a facing side of two adjacent battery elements 20 in such a way that there is thermal contact between the respective battery element 20 and the deformation element 30 . In the arranged and inserted state in the housing 12, the battery elements 20 thus have a distance d from one another that is predetermined by the deformation elements 30.

The deformation elements 30 are according to 1 each formed as a deformable enveloping medium 31 filled with a fluid. The envelope medium 31 thus forms an outer envelope for the fluid inside. In the present case, the fluid can be a gas 32, for example. Air, for example, is a suitable gas. The respective deformation element 30 can thus be an air-filled cushion or air cushion, for example. The enveloping medium is formed from a deformable or flexible, in particular an elastic, material. In order to provide the compressive force, the deformation elements 30 have an internal pressure in a specified operating state of the battery elements 20 which is in a predetermined internal pressure value range. The internal pressure value range can include, for example, 0.1 to 0.4 Pascal. As a result, the battery elements in the intended operating state, as shown in 1 a predetermined volume V is shown. The intended operating state can be intended battery operation of the drive battery 10, in which the battery elements 20 are designed to provide the electrical energy for driving the motor vehicle.

If the aforementioned swelling, ie cell respiration, of the respective battery element 20 occurs during operation of the drive battery 10 , the deformation elements 30 can absorb a force that results from the swelling of the battery element 20 . In this case, for example, the gas 32 can be compressed on the inside and the enveloping medium 31 can be deformed. In this way, a pressure that is as constant as possible or a constant force can essentially be exerted on the battery elements 20 . The battery elements 20 age or deplete less quickly. In this case, the predetermined distance d between the battery elements 20 remains essentially unchanged in the event of swelling or the volume changes caused by aging.

According to the configuration of the battery arrangement 1 the battery elements 20 are designed to be displaceable in the battery housing 12 relative to the stacked assembly 11 . That is, they can be shifted in the stacking direction R under certain operating conditions. A corresponding operating condition will be referred to later 2 even more detailed.

For electrical contacting of the battery elements 20, the battery arrangement 1 according to FIG 1 another contacting unit 14. The contacting unit 14 can be, for example, a printed circuit board or printed circuit board with conductor tracks and connection contacts, through which a suitable electrical interconnection of the battery elements 20 with one another and with the battery connection poles 13 can be implemented.

According to 1 the contacting unit 14 has a plate-shaped body with a rectangular cross section. The contacting unit 14 is arranged at an upper end in the housing 12 above the stacked assembly 11 . This means that the contacting unit 14 essentially rests on the battery elements 20 . A surface of the body of the contacting unit 14 covers each of the battery elements 20 in the stacking direction R. For each battery element 20, the contacting unit 14 includes in 1 an electrical connection contact, which is designed as a busbar 15 in the present case. The respective battery element 20 is electrically conductively connected to the respective busbar 15 via a respective connection contact 21 or battery contact. The connection contact 21 can be, for example, a positive pole or negative pole of the battery element. Alternatively, the connection contact can be a control contact for control electronics of the battery element 20 . The battery element 20 can be a controllable battery cell, for example. The busbars 15 are flat in the stacking direction R. This means that each of the busbars 15 offers a much larger contact area than is required by the respective connection contact 21 . A dimension of the busbar 15 in the stacking direction is thus larger than an area of the respective connection contact 21 by a predetermined limit amount. For example, the busbar area can be 3 times or 5 times or 10 times larger. This configuration of the busbars 15 plays a role in the previously mentioned shifting of the battery elements 20 and will be examined in more detail later. In 1 only one connection contact 21 and only one busbar 15 is shown for each battery element 20 for a better overview. Of course, it is clear that a typical battery element 20 can usually have two or more such connection contacts.

In addition to absorbing swelling forces, the deformation elements 30 can also have another function. This is in 2 explained in more detail. The further function is a prevention function in which, in the event of a thermal runaway of one of the battery elements 20, the remaining battery elements are to be shielded from the continuous battery element 20. For this shows 2 a schematic representation of the battery arrangement 1 according to FIG 1 , in which one of the battery elements 20 has a predetermined heating state Z. For a better overview are in 2 compared to 1 only the most necessary reference numbers are entered.

According to 2 the middle one of the five battery elements 20 in the stacked assembly 11 is in the heating state Z. In the present case, heating state Z means a state that differs from the intended operating state of the battery elements 20 differs. The heating state Z can, for example, be a so-called thermal runaway, ie a thermal runaway of the battery element 20. In the process, the respective battery element 20 heats up to a predefined temperature limit of approximately 84 degrees Celsius or higher, at which irreversible chemical reactions of the active material of the battery element 20 take place. These reactions are endothermic processes that release a large amount of energy in the form of heat. The battery can heat up from the initial 84 degrees to as much as 1,200 degrees within a few seconds. The battery element 20 catches fire. If there is insufficient thermal insulation of the remaining battery elements 20 in the stacked assembly 11, the heating of a battery element 20 can lead to thermal propagation and thus to a chain reaction of the remaining battery elements 20. The heating or overheating and the resulting thermal runaway can be caused, for example, by a short circuit or by impurities in the active material.

The additional function of the deformation elements 30 in the drive battery 10 is now to ensure sufficient thermal insulation between the battery elements 20 in the event that the heating state Z is present, in order to prevent propagation. For this purpose, the enveloping medium 31 is initially formed from a temperature-resistant, deformable material. The enveloping medium 31 is thus stable with respect to the heating state Z. A melting point of the cladding medium 31 or a destruction temperature, which leads to a defect in the cladding medium 31, can thus be higher than a temperature with which the deformation element 30 can be applied when the heating state Z occurs. A metallic material comprising steel or aluminum, for example, is suitable as the material. The enclosing medium 31 can thus be formed from sheet metal, for example. Alternatively, a fiber-reinforced plastic can be used as the material for the enveloping medium 31 . Aramide, for example in the form of Kevlar fibers, or glass, for example in the form of glass fibers, or carbon, for example in the form of small carbon nanotubes, can be incorporated into the plastic as fiber-reinforcing material. In addition or as an alternative, the enveloping medium 31 can be constructed, for example, in multiple layers from a plurality of materials in different layers. For example, a non-temperature-resistant fiber composite material can be used as the base layer, which is surrounded by a temperature-resistant coating material as an additional layer.

Due to the design of the deformation elements 30, the following can now happen during thermal runaway: In the heating state Z, a temperature of the battery element 20 increases. Due to the thermal contacting of the adjacent deformation elements 30, the temperature of the adjacent deformation elements 30 also increases. The heating of the gas 32 increases First, an internal gas pressure of the respective deformation element 30. Since the deformation element 30 is designed to be deformable and the battery elements 20 are mounted in the housing 12 so as to be displaceable along the stacking direction R, the deformation element 30 can expand. There is an increase in volume to a volume V1. The actual increase in the volume, that is to say the amount of the increase in volume, depends on a respective temperature of the continuous battery element 20 . This is because a property of gases, described by the general gas equation, is used to expand when the temperature rises. The volume increases, a density of the gas decreases, an internal gas pressure of the gas 32 in the enveloping medium 30 can essentially remain constant or at most increase slightly.

Due to the increase in volume, the remaining or intact battery elements 20 are displaced relative to the continuous battery element 20 in the stacked assembly 11 and in particular are pushed away from the continuous battery element 20 . This means that the battery elements 20 are pushed away from the continuous battery element 20 in the stacking direction in the stacked assembly. Since the housing 12 is essentially non-deformable and the remaining deformation elements 30 are in a colder environment, the remaining deformation elements 30 can be put into a second preventive state by the displacement of the adjacent battery elements 20 in the stacked assembly 11 . In the process, the deformation elements 30 are compressed or pressed together. A reduction in volume to a volume V2 results.

Due to the increase in volume and the reduction in volume of the deformation elements 30, the intact battery elements 20 are displaced. The design of the conductor rails 15 then also proves to be useful here. It can thus be ensured that the battery elements are still electrically conductively connected via the contacting unit 14 even when the heating state Z is present, ie the displaced battery elements 20 .

This results in the advantage that, for example, when the heating state is detected, for example by means of a monitoring device, rapid discharge of the remaining battery elements occurs 20 can be performed. Alternatively, the remaining battery elements 20 can still be addressed or controlled via the control connection, for example by a battery management system. For example, when the heating state Z of one of the battery elements is detected, the remaining battery elements 20 can be deactivated or switched off by activation with the battery management system.

The overall increase in volume also increases the distance d between the adjacent battery elements 20 . The battery elements 20 adjacent to the continuous battery element 20 thus have, as in 2 shown, a greater distance d1 than the predetermined distance d in the intended operating state. The reduction in volume also causes a reduction in the specified distance d between the adjacent battery elements 20 . As in 2 shown, due to the reduction in volume or compression of a compressed deformation element, a distance d2 between the adjacent battery elements 20 is smaller than the predetermined distance d in the intended operating state. The increase in distance, ie the respective distance d1, can be greater by two to five millimeters than the specified distance d, for example. Similarly, the distance d2 can be two to five millimeters smaller than the specified distance d, for example.

This results in the advantage that a distance between the intact battery elements 20 and the continuous battery element 20 can be increased without increasing the space required for the drive battery 10 .

In order to be able to make the compression or reduction in volume of the deformation elements in the second state of prevention even more effective, each deformation element 30, as in 1 and 2 shown, a valve element. The valve element is, for example, a pressure compensation element that is worked into or integrated into the enveloping medium 31 . This pressure compensation element has, for example, exactly two positions, namely an open position and a closed position. In the open position, a mass flow or volume flow of the gas 32 from the interior of the deformation element 30 to the environment, ie into the battery housing 12, is possible. In the closed position, on the other hand, the mass flow or volume flow is blocked. The changeover between the open and closed position takes place in the respective pressure compensation element 33 as a function of a predetermined pressure value which acts on a valve body of the pressure compensation valve 33 from the deformation element 30 . This pressure limit value is set, for example, in such a way that it is reached when the deformation elements 30 are compressed, ie when the second prevention state is assumed. As in 2 shown, the gas 32 can thus flow out of the enveloping medium 31 from the compressed or to be compressed deformation elements 30 . For the expanded deformation elements 30, however, the pressure compensation valve 33 is in the closed state.

The effect of the deformation elements 30 can be briefly summarized again as follows: If there is a thermal problem in a battery element or a battery cell due to a defect or external influences and thus, for example, a thermal runaway, the damaged cell heats up and gives a Part of the heat into the neighboring air cushions. This heats the gas in the cushions. The pressure in the two adjacent air cushions increases with temperature. This creates a pressure difference between the heated air cushion and the rest, i.e. the cold air cushion. Since there should be physical equilibrium in the cell network, a pressure equalization takes place, during which the cold, i.e. the remaining, air cushions are compressed. The heated air cushions expand. This causes a cell shift, i.e. a shift of the battery elements. The neighboring cells of the damaged cell are pushed away from it. This creates a greater distance to the damaged cell. This reduces the heat input into the neighboring cells and thus prevents thermal propagation. A maximum distance between the cells is generated without requiring additional installation space.

Overall, the exemplary embodiments show how airbags can be used between battery cells to prevent thermal propagation.

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 3529727 A1 [0005]
• DE 102019128433 B3 [0007]
• DE 102012224330 A1 [0008]

Claims (10)

Battery arrangement (1) for a motor vehicle with a multiplicity of battery (20) and deformation elements (30) which together form a stacked composite (11) which is arranged in a battery housing (12) of the battery arrangement (1), wherein in the stacked composite (11) at least one of the deformation elements (30) is arranged in thermal contact between two battery elements (20) arranged adjacent to one another at a predetermined distance (d), the respective deformation element (30) consisting of a deformable element filled with a fluid (32). Enveloping medium (31) is formed, characterized in that the deformation elements (30) in the stacked assembly (11) have a predetermined internal pressure in a normal state, and the battery elements in the battery housing (12) in a predetermined stacking direction (R) of the stacked assembly (11 ) are slidably mounted, and in the event that in the stacked assembly (11) at least one of the battery elements (20) specify a n heating state (Z), which is formed in the deformation element (30) adjoining the stacked assembly (11), in a first prevention state, to provide an increase in volume by a predetermined limit amount, and through the increase in volume at least a displacement of the remaining battery elements (20) in the To effect battery housing (12). Battery arrangement (1) according to claim 1 , wherein the fluid (32) is a gas, and when the heating state (S) occurs, the remaining deformation elements (30) are formed in the stacked assembly (11), depending on the respective increase in volume of the respective adjacent deformation element (30) in a second Preventive state to provide a volume reduction, and the plurality of deformation elements (30) is designed to cause a displacement of the battery elements (20) in the stacked assembly (11) by the increase in volume and the volume reduction. Battery arrangement (1) according to claim 2 , wherein the deformation elements (30) each have at least one valve element (33) for providing a mass flow of the gas (32) out of the enveloping medium (31), wherein the respective valve element (33) is designed to control the mass flow as a function of a predetermined pressure value of the gas (32) to a valve body of the respective valve element (33), the pressure value being predetermined as a function of the volume reduction, and/or the battery arrangement (1) comprises a monitoring device which is designed to monitor the heating state (Z) and/or or to detect the reduction in volume and then to provide a control signal for activating a respective actuator of the valve elements (33) of the remaining deformation elements (30) and thereby bring about the mass flow. Battery arrangement (1) according to claim 1 , wherein the fluid (32) is a liquid, and the deformation elements (30) each have at least one valve element (33) for providing a mass flow of the liquid out of the enclosing medium (31), and the battery arrangement (1) comprises a monitoring device which is designed to detect the heating state (Z) and then to provide a control signal for activating an actuator of the valve elements (33) of the remaining deformation elements (30) that are not adjacent to the battery element (20) in the heating state (Z) and thereby to to cause mass flow. Battery arrangement (1) according to one of the preceding claims, wherein the enveloping medium (31) has at least one material which is designed to be temperature-resistant at least for the heating state (Z). Battery arrangement (1) according to claim 4 , wherein the enveloping medium (31) comprises a metallic material comprising steel or aluminum, or comprises a fiber-reinforced plastic, wherein the plastic comprises aramid or glass or carbon as a fiber-reinforced material, or comprises a fiber composite material, wherein the fiber composite material is coated with a coating material, which is designed to be temperature-resistant at least for the heating state (Z). Battery arrangement (1) according to one of the preceding claims, wherein an electrical contacting unit (14) is provided for electrically contacting the battery elements (20), which is arranged at least in sections along a surface of the stacked assembly (11) lying in the stacking direction (R), and which provides a flexible conductor section for each of the battery elements (20) for connection to the contacting unit (14), which is designed to switch between a compressed state and a stretched state depending on the displacement. Battery arrangement (1) according to one of the preceding Claims 1 until 6 , wherein for the electrical contacting of the battery elements (20) an electrical contacting unit (14) is provided, which at least partially along a surface of the stacked assembly (11) lying in the stacking direction (R), and which has a respective busbar (15) for each of the battery elements (20) for electrical connection to the contacting unit (14), which extends along the stacking direction (R) extends over a given stretch of road. Battery arrangement (1) according to one of the preceding claims, wherein the deformation elements (30) are designed to deform as a function of an aging-related or operational deformation of the battery elements (20). Motor vehicle with a battery arrangement (1) according to one of the preceding claims.

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