FIELD

The invention relates to a separating device for a battery module. The separating device comprises a first separating element and a second separating element, which are arranged congruently with respect to one another and adjacent one another. The first separating element and the second separating element are formed from a heat-conducting material. The invention also relates to a battery module, which comprises the separating device according to the invention, and a motor vehicle having the battery module according to the invention.

BACKGROUND

Battery modules with battery cells, particularly lithium-ion cells, heat up during the charging and discharging phase. If this temperature reaches a critical value, this may result in a spontaneous combustion, which can also be characterized as a propagation. In addition, the battery cells expand during the charging and discharging phase, which can also be characterized as swelling. In order to prevent spread of the propagation from one battery cell to the next battery cell or damage due to an expansion of the battery cells, it is known from the general prior art to arrange separating plates, for example made of a ceramic material, between the battery cells. A disadvantage of such separating plates is that the separating plates are usually formed to be very stiff and cannot handle the forces from the expansion of the battery cells during the charging and discharging phase; this can lead to high voltages within the battery module and within the respective battery cells. Furthermore, the separating plates isolate very strongly to the extent that hardly any or no heat can be dissipated via the separating plates.

Such type of separating plate is described, for example, in US 2017/0194615 A1. The separating plate, which can also be characterized as a battery cell separator, contains an upper and a lower surface. A structure extends between the upper surface and the lower surface and contains a first contoured surface on a first side of the structure and a second contoured surface on a second side. The first contoured surface and the second contoured surface converge between the upper surface and a middle of the structure and diverge between the middle and the lower surface. A disadvantage of this separating plate is that it is constructed especially complexly.

In order to dissipate heat from the battery cells via separating plates between the battery cells, it is known from the prior art to arrange separating plates with integrated cooling channels between the battery cells.

Thus, US 2011/0206964 A1 describes, for example, a cooling assembly for a battery assembly. The cooling assembly has a cooling plate, in which a flow channel is integrated. The cooling plate is arranged between the battery cells of the battery assembly in order to transfer heat from the battery cells adjacent the cooling plate to a fluid flowing in the flow channel.

US 2015/0200429 A1 discloses a heat-dissipation unit. The heat-dissipation unit comprises a main structure, which has a fluid channel with a fluid inlet and a fluid outlet. The heat-dissipation unit is arranged between the battery cells of a battery. The fluid channel is designed such that, when a coolant flows through the fluid channel, at least one side wall of the fluid channel is pressed outward by the coolant, expands, and has contact with the surface of the heat-generating battery cell.

One disadvantage of an integrated forming of a cooling channel and/or flow channel within the separating plate is that the fluid channel can become damaged during expansion of the battery cells and a sufficient dissipation of heat hereby can no longer be guaranteed.

SUMMARY

Thus, the object of the present invention is to provide an improved separating device which is constructed, particularly in the design, to be especially simple and robust, can handle external voltages, and simultaneously can dissipate heat especially well.

This object is achieved by means of a separating device, a battery module, as well as a motor vehicle.

The invention provides for a separating device for a battery module. The separating device comprises a first separating element and a second separating element, which are arranged congruently with respect to one another and adjacent one another. In other words, the first separating element and the second separating element may be arranged parallel to one another and adjacent one another. In other words, the first separating element and the second separating element can be arranged directly above one another and on top of one another, particularly completely overlapping, in a supportive manner, or coplanar as relates to one another. In particular, the two separating elements are connected, particularly welded, to one another preferably on the edge or along a common outer edge. Preferably, the first separating element and the second separating element are formed equivalently or identically. In other words, the first separating element and the second separating element may have the same geometry and/or dimensions and/or shape. Preferably, the first and the second separating element may have a rectangular shape. Especially preferably, the first separating element and the second separating element in this case are formed in the shape of a plate. In other words, the first separating element and the second separating element may be formed as a plate, particularly as a separating plate. Furthermore, the first separating element and the second separating element are formed from a heat-conducting material.

The invention is characterized in that the first separating element and the second separating element enclose a chamber. In other words, a chamber is arranged between the first separating element and the second separating element. In other words, the first separating element and the second separating element are formed such that they surround a chamber or form a chamber between them. The term “chamber” refers particularly to a cavity. Preferably, the chamber is arranged centrally or centrically between the first separating element and the second separating element. In particular, the first separating element and the second separating element extend in a vertical or longitudinal direction and in a width direction, wherein the vertical direction and the width direction span a plane between each other, wherein the chamber is arranged centrally as relates to the plane between the separating elements—first separating element and second separating element. In particular, the chamber is closed. Preferably, the remaining first separating element and the remaining second separating element form an edge or a frame about the chamber, particularly outside of the chamber. The separating device can also be characterized as a membrane due to the multiple layers comprising the first separating element and the second separating element as well as the chamber enclosed therein. The term “membrane” here particularly refers to a thin structure with different properties which have a large surface expansion as compared to the thickness thereof. The membrane particularly has the capacity for separation.

Furthermore, the first separating element and the second separating element have embossments or ribs which correspond to one another for forming the chamber. The term “embossment” particularly refers to a step pressed into the first separating element and the second separating element with a defined shape or groove or recess or notch or impressions. In this case, the embossments preferably have a base surface in the recesses. Preferably, the embossments are formed by stamping or a stamping process. The term “ribbing” refers particularly to ribs.

Furthermore, the embossments of the first separating element extend away from the second separating element, and the embossments of the second separating element extend away from the first separating element. In other words, the first separating element and the second separating element have curves due to the embossments, which curves extend away from the opposite separating element. In other words, due to the curves, the first separating element curves away from the second separating element in the region of the chamber, and the second separating element curves away from the first separating element in the region of the chamber. Furthermore, the embossments of the first separating element and of the second separating element are arranged opposite one another. Preferably, the respective embossments have a U shape in the cross-section which extends particularly perpendicular as relates to the plane which is spanned by the vertical and width directions.

The embossments have the advantage that a stiffness of the first separating element and of the second separating element can thereby be increased, whereby the respective separating elements and thus the separating device is designed to be especially robust and stable. The stiffness of the first separating element and of the second separating element can be adjusted as a function of a number of embossments.

Furthermore, the chamber is divided into several chamber regions which are formed by the embossments of the first separating element and of the second separating element. The embossments of the first and of the second separating element can jointly form the chamber and form different chamber regions of the chamber due to the shape thereof. The chamber regions are preferably, particularly fluidly, coupled or connected to each other.

The separating device is formed to be multifunctional due to the formation of the first separating element and the second separating element from a heat-conducting material as well as the chamber between the separating elements—first separating element and second separating element. For one thing, heat can be absorbed and dissipated especially well by the separating elements, and external forces acting on the separating device can be handled and compensated for especially well.

One advantageous embodiment provides that the embossments have a rectangular contour. The embossments preferably form a loop or track which has a rectangular shape. Preferably, the chamber has or the chamber regions have a rectangular shape in the cross-section which extends parallel to the plane of the first and of the second separating element, which particularly is spanned between the vertical and the width directions. Alternatively, it may be provided that the embossments have an oval contour or a star-shaped contour or a grid structure. Especially preferably, the chamber regions are formed in the shape of a channel and/or cuboid by means of the embossments. The separating elements—first separating element and second separating element—have especially good stiffness due to the contour of the embossments, whereby the separating device is formed to be especially robust.

The invention is based on the knowledge that a pressure profile acting on the separating device can be defined. Correspondingly, an advantageous refinement provides that the contour of the embossments and/or an expansion of the embossments and/or an arrangement of the embossments on the respective separating elements can be adapted to a pressure profile, which particularly acts on the separating device by means of the battery cells. For example, a pressure profile acting on the separating device can be specified by an FM calculation, and the embossments are subsequently formed.

In an advantageous manner, the first separating element and the second separating element are formed from steel as the heat-conducting material. In particular, the first separating element and the second separating element are formed as steel plates. This results in the advantage that the first separating element and the second separating element are formed to be especially robust and can simultaneously absorb and dissipate heat especially well.

According to an advantageous refinement, it is provided that the chamber is filled with a gas, particularly with a flame-retarding and/or insulating gas, which especially preferably comprises carbon dioxide or halogen or monoammonium phosphate. In other words, the chamber can preferably be filled with a gas which has a predetermined fire resistance. The term “insulating” particularly means that the gas has an insulating effect, particularly a predetermined heat resistance. Gases are particularly compressible. A spring stiffness of the separating device can be set with the aid of the gas, particularly the type and/or quantity of the gas. The gas can be supplied to the chamber during the manufacturing process of the separating device, for example in a pressure chamber, in which the first separating element and the second separating element are connected to one another. Alternatively, the gas can be supplied to the chamber with an injection needle in that the injection needle penetrates or punctures one of the separating elements in the region of the chamber. If the gas is supplied to the chamber by means of the injection needle, the opening caused by the injection needle can be closed, particularly welded.

Additionally or alternatively, it may be provided that the chamber is filled with a liquid or an additive, particularly a flame-retarding and/or insulating liquid or a flame-retarding and/or insulating additive. For example, the additive may be formed as a powder. Alternatively, the flame-retarding and/or insulating fluid, which may be formed as a liquid or a gas, can contain an additive. Furthermore, the flame-retarding and/or insulating fluid may be formed as a phase change material (PCM). A phase change material is particularly a substance or a fluid or a material which releases or absorbs sufficient energy during the phase transition in order to provide useful heat or cooling.

A further advantageous embodiment provides that the separating device has a third separating element which is arranged between the first separating element and the second separating element, wherein the third separating element is formed as a fabric board or fiberboard. Especially preferably, an expansion and/or geometry of the third separating element is adapted to an expansion and/or geometry of the first separating element and of the second separating element. In other words, a dimension and/or shape of the third separating element is adapted to a dimension and/or shape of the first separating element and/or of the second separating element. Preferably, the separating element has a rectangular and/or plate-shaped shape. Preferably, the third separating element separates the chamber into two chamber halves. Especially preferably, both chamber halves can be filled with the same fluid, particularly a gas or a liquid, or with various fluids.

Due to the gas and/or the liquid and/or the additive and/or the third separating element, cell propagation can be reduced or inhibited, and the resulting fire damage within the battery housing is reduced or even prevented by means of the gas and/or additive and/or liquid and/or the third separating element present in the chamber.

According to an advantageous refinement, it is provided that the separating device has at least one opening, by means of which the flame-retarding and/or insulating fluid, particularly the gas or the liquid or the additive, can be removed from the chamber, particularly when a temperature and/or a pressure in the chamber reaches a predetermined value. The opening in this case is preferably formed as a burst opening. For example, if the heat input acting on the separating device is too high during a propagation, for example a temperature or a pressure in the separating device reaches a predetermined value, the fluid can thus exit the chamber via the burst opening. For example, the separating device has a channel at a point or in a predetermined region which connects, particularly fluidly, the chamber to an environment or an outer region of the separating device. The channel or the opening can be closed and opened by means of a valve or a closing element as soon a predetermined, critical value is reached within the chamber. The opening provides the advantage that, in the event of a propagation, the flame-retarding and/or insulating fluid can exit the chamber especially easily and rapidly in order to prevent a spread to other battery cells.

The invention also includes a battery module which comprises several battery cells, particularly lithium-ion cells, wherein the battery module further has at least one separating device which is arranged between two adjacent battery cells. Preferably, the battery module has several separating devices, wherein each separating device is arranged between two adjacent battery cells. The battery cells in this case can be arranged next to one another in a main extension direction of the battery module. In the region of the chamber, the first separating element rests, at least partially, on a battery cell, particularly on an outer surface of the battery cell which is facing the first separating element, and the second separating element rests, at least partially, on an adjacent battery cell, particularly on an outer surface of the battery cell which is facing the second separating element. In particular, a battery cell and a separating device and a further battery cell are arranged sequentially in the battery module, in the main extension direction of the battery module. If the battery module has several separating devices, a battery cell and a separating device are thus arranged sequentially alternating, particularly in the main extension direction of the battery module. Developing heat can be especially reliably dissipated from the battery cells by means of the direct contact of the battery cells with the separating device. Furthermore, due to the arrangement of the separating device between the battery cells, an application of force due to an expansion of the battery cells can be accommodated and/or compensated for especially well by the separating device.

One advantageous embodiment provides that the battery module has a heat-dissipation device, wherein the battery cells and the separating device are arranged on the heat-dissipation device, particularly in a vertical direction of the battery module. In particular, the vertical direction of the battery module extends perpendicular as relates to the main extension direction. Preferably, the vertical direction of the battery module and/or the separating device extends in the gravitational direction. Preferably, the battery module has a housing with a housing cover and a housing base arranged opposite the housing cover, wherein the battery cells and the separating device are arranged on the housing base. Especially preferably, the heat-dissipation device is arranged between the housing base and the battery cells and the separating device. Heat can be especially reliably dissipated from the battery module by means of the heat-dissipation device.

In an advantageous manner, the heat-dissipation device comprises a thermally conductive paste and/or a cooling element. Preferably, the thermally conductive paste can be arranged between the cooling element and the battery cells and/or the separating device. The cooling element can be formed as a cooling plate. The heat-dissipation device is constructed especially simply as relates to the design by means of the cooling element and/or the thermally conductive paste.

Finally, the invention also includes a motor vehicle with the battery module according to the invention. The vehicle according to the invention is preferably designed as a motor vehicle, particularly as a passenger car or commercial vehicle, or as a passenger bus or motorcycle.

The invention also includes refinements of the battery module according to the invention and of the motor vehicle according to the invention, which have features as they have already been described in association with the refinements of the separating device according to the invention. For this reason, the corresponding refinements of the battery module according to the invention and of the motor vehicle according to the invention are not described again here.

The invention also comprises the combinations of the features of the described embodiments.

