DE102012220393A1 - Battery module with two tension plates and two clamping plates - Google Patents

Abstract

A battery module (200) with a tension element (230), a clamping plate (240) and a plurality of battery cells (100) is specified. The tension element (230) and the tensioning plate (240) are designed to encompass the battery cells (100) in an assembled state. In an initial state, the tensioning plate (240) has a convex shape with respect to the battery cells (100) and is designed, in the assembled state, a compressive force (150) on the plurality of battery cells (100) in a direction along a longitudinal direction (231 ) of the battery module (200). The clamping plate (240) has a layer (245) which, in the assembled state, exerts the pressure force (150) on a contact surface (130) of the layer (245) with a battery cell (100A) arranged adjacent to the clamping plate (240) ) to distribute.

Description

Field of the invention

The invention relates to battery modules. In particular, the invention relates to a battery module and a battery unit for an electric engine.

State of the art

Battery units, in particular battery units for electric and hybrid vehicles, may for example comprise lithium-ion cells for the provision of electrical energy and be constructed as follows: Several battery cells form a battery module and a plurality of battery modules form a battery unit. In this case, prismatic, for example rectangular battery cells are known, which are combined for life and handling reasons to battery modules. The battery cells can be arranged in the summary to a battery module so that the battery cells with the larger side surface of the two side surfaces in a prismatic structure of the battery cells each adjacent to the adjacent battery cell. When combining the battery cells to form a battery module, a pressure force on the first battery cell and on the last battery cell in each case in the direction of the adjacent battery cells, which can extend the life of the individual battery cells. This results from the fact that, especially with lithium-ion cells in the course of the life of such a battery cell and by an increasing number of charging and discharging an increase in volume can be detected, which can adversely affect the life of these battery cells. The pressure on the battery cells of a battery module can counteract this volume increase of the individual battery cells and thus increase the life and performance of the battery cells and the battery module.

To provide the appropriate pressure, for example, curved sheets can be provided on the respective sides of the battery module, which are tensioned by means of tension elements in the direction of the pressure force to be exerted. In order to ensure a uniform pressure distribution to the battery cells, which are located at the edges of a battery module, a plate between the battery cell and the pressure element are provided on each side of the battery module to each of the pressure elements. The plate is, for example, a stable steel plate, since the corresponding compressive forces can be between 10 kN and 15 kN, for example. Due to its mechanical strength, steel is well suited for use in such a plate.

DE 10 2009 000 660 A1 describes the general structure of a battery module, which is used for the power supply of an electric motor.

Summary of the invention

With the invention, a battery module is provided, which is characterized by a lower weight compared to conventional battery modules, so that in particular when using such a battery module in vehicles, a lower total weight of the vehicle can be made possible.

It is a battery module and a battery unit according to the features of the independent claims specified. Further developments of the invention will become apparent from the dependent claims and from the following description. The battery module and the battery unit can be used in particular for the power supply of an electric motor.

According to a first aspect, a battery module with a tension element, a clamping plate and a plurality of battery cells is specified. In this case, the tension member and the tension plate are designed to comprise the battery cells in an assembled state, wherein the tension plate in a starting state with respect to the battery cells has a convex shape and is executed, in the mounted state, a compressive force on the plurality of battery cells in a Direction along a longitudinal direction of the battery module exercise. The battery module is characterized in that the clamping plate has a layer which is designed, in the mounted state, to distribute the pressure force on a contact surface of the layer with a battery cell arranged adjacent to the clamping plate.

By this construction of the clamping plate, for example, the use of a plate for the pressure distribution can be avoided on the battery cells, so that the corresponding weight of this pressure distribution plate can be saved. At a mass of e.g. 300 g per pressure distribution plate and with eight battery modules per battery unit, a weight of 4.8 kg per battery unit can be saved by dispensing with the pressure distribution plates with two pressure distribution plates per battery module.

The tension element and the tension plate can be arranged in the assembled state, in particular at right angles to each other. The layer on the Clamping plate may be elastic and / or plastically deformable. In this case, the layer may in particular be mechanically connected to the clamping plate. For example, the layer may be adhesively bonded to the clamping plate or be mechanically coupled to the clamping plate via a fastening element. In the assembled state, the layer can distribute the pressure force of the clamping plate on the battery cell arranged next to the clamping plate in particular evenly.

That the tension plate has a convex shape with respect to the adjacent battery cells means that the tension plate is curved in the unassembled state. In one embodiment, the course of the clamping plate, for example, describe a portion of a circular path or an elliptical course, wherein the clamping plate rests against the first battery cell, that the side surface of the battery cell, against which the clamping plate is applied, a tangential surface to the clamping plate.

According to one embodiment, the layer provided on the clamping plate has a fiber composite.

The fiber composite may be, for example, fiber-reinforced polyamide, which has, for example, a glass fiber content of 30%. The fiber composite has a high mechanical strength so that it can be well suited for use and use with the compressive forces present in the battery module.

According to a further embodiment, the layer provided on the clamping plate has a plastic, wherein the fiber composite surrounds the plastic.

The plastic is an inner core and the fiber composite an outer sheath of the core. This structure of the layer can allow a uniform pressure distribution of the pressure exerted by the clamping plate pressure on the battery cell.

According to a further embodiment, the plastic comprises a polypropylene.

The polypropylene may be characterized in that it is plastically or elastically deformable, so that the layer between the clamping plate and the adjacent battery cell arranged or deformed so that a uniform pressure distribution on the side surface of the battery cell is made possible.

According to a further embodiment, the layer is designed to be electrically insulating.

This makes it possible that the clamping plate, which may be made of steel, is separated by an electrically insulating layer of the battery cell. This can in particular improve the safety during assembly and use of the battery module. Also, this can simplify an assembly process of the battery module, since no additional insulating layer between the clamping plate and the battery cell must be introduced.

In accordance with a further embodiment, the layer has a tapering cross section at least in sections in a transverse direction of the battery module running transversely to the longitudinal direction.

The transversely tapering cross-section can be carried out, so to speak, as a counterpart to the curved course of the clamping plate and, in addition, allow the uniform pressure distribution on the adjacent to the clamping plate arranged battery cell. In particular, at the beginning of the assembly process, when the clamping plate is still in its initial state and has not yet been bent at least partially against the curvature of the clamping plate by the clamping force of the tension elements, the sectionally tapered cross section can help that just at the beginning of the assembly process, the clamping force is not rests on a small contact surface, but that just this contact surface is increased.

According to another embodiment, each battery cell of the plurality of battery cells is a rechargeable battery.

The battery module as described above and below is particularly suitable for use with rechargeable batteries, since such a battery module allows multiple use over a long period of time.

In one embodiment, the rechargeable battery is a lithium-ion cell.

The battery module as described above and below is designed to exert a compressive force on the battery cells by the tension element and the clamping plate in such a way that it counteracts a volume increase typical of lithium-ion cells during their lifetime. By reducing or even preventing this increase in volume, the lifetime of the lithium-ion cells is also increased.

According to another embodiment, the battery cells are prismatic.

This means that opposite surfaces of the battery cells are parallel to each other, as is the case, for example, in the case of a rectangular or parallelepiped construction of the battery cells. The volume increase during the lifetime, in particular of lithium-ion cells, can be increased in particular by the prismatic structure of battery cells. In this case, the increase in volume may result from the prismatic construction of a battery cell, since the housing of the battery cell may not be able to counteract the increase in volume with the necessary pressure forces in order to reduce or even completely prevent the volume increase. The battery module as described above and in the following can reduce or prevent the increase in volume of, in particular, prismatic battery cells, so that these battery cells can have an increased service life.

According to another aspect, there is provided a battery unit for an electric power engine having a plurality of battery modules as described above and hereinafter.

The battery unit can be provided for example as energy storage for the drive of electric motors. In particular, the battery pack may be used for use in vehicles powered by such an electric motor. The weight of the battery unit saved by the construction of the battery modules can thereby benefit the energy consumption of such a vehicle, as this can also reduce the weight of the vehicle.

In one embodiment, the battery modules are prismatic in an assembled state.

This means that the clamping plate of a battery module are bent straight in a state mounted in the battery unit due to a tension force applied by the pulling elements, this bending being made possible from the curved state to the straight state due to the material elasticity of the clamping plate. The prismatic shape achieved in the mounted state of the battery modules can also enable a space-saving use or a space-saving installation of the battery modules in the battery unit.

In the following, embodiments of the invention will be described with reference to the figures.

Brief description of the drawings

1 shows a battery unit according to an embodiment.

2 shows a battery module according to an embodiment.

3A shows a schematic representation of a battery module according to an embodiment in a non-assembled state.

3B shows a schematic representation of a battery module according to an embodiment in an assembled state.

4A shows a sectional view of a side view of a battery module according to an embodiment.

4B shows a plan view of a battery module according to an embodiment.

5 shows a schematic representation of a clamping plate for a battery module according to an embodiment.

The illustrations in the figures are schematic and not to scale. If the same reference numerals are used in the following description of the figures, these relate to the same or similar elements.

Embodiments of the invention

1 shows a battery unit 300 , wherein the battery unit eight battery modules 200 each of which has six battery cells 100 having.

It should be noted that a battery unit may also have more or less than eight battery modules, and that a battery module may also have more or less than six battery cells.

2 shows a schematic representation of a plan view of a battery module 200 , The battery module 200 has six battery cells, which in the longitudinal direction 231 the battery module are arranged side by side. The battery cells each have a first voltage connection 110 and a second voltage connection 120 in each case, the first voltage terminal of a battery cell with the second voltage terminal of the adjacent battery cell is electrically connected so that all the battery cells 100 of the battery module 200 represent a series connection, so for the battery module 200 a first voltage connection 210 and a second voltage connection 220 results. In this case, the battery cells or their voltage terminals with a battery cell connector 115 electrically connected.

Especially with the use of rechargeable lithium-ion cells may be an increase in volume of battery cells of rectangular cross-section through an increasing number of charging, resulting in the in 2 illustrated embodiment, an increase in volume of the individual battery cells along the longitudinal direction 231 of the battery module results. This would, for example, the extension of the entire battery module in the longitudinal direction 231 change, that is, increase, and in addition the performance of the individual battery cells would be reduced by the volume increase.

To counteract this increase in volume, so must a compressive force 150 acting on the side surfaces of the battery cells, wherein the printing direction of the pressing force 150 along the longitudinal direction 231 of the battery module runs.

The battery module 200 has two longitudinal tension elements 230 on, with the tension elements at each of its ends, each with a clamping plate 240 at the junction 235 mechanically connected. The two tension elements 230 and the two clamping plates 240 surround the six battery cells 100 of the battery module 200 , The clamping plates 240 each have a curved course and are arranged so that the battery cells lying on the edge touch the outer edge of the curved course of the clamping plates, that is, the respective outer edges of the curvature of the two clamping plates point to the respective opposite clamping plate.

To get out of the in 2 shown unmounted state of the clamping plates to get into the assembled state, the clamping plates in the region of the joint 235 loaded with a compressive force in the direction of each of the opposite clamping plate until the two clamping plates, for example, have a straight course, so that a battery cell adjacent to the clamping plate is touched over its entire width, and then a mechanical connection between the clamping plates and the tension element is produced. Due to the preformed or curved course of the clamping plates in the unassembled state, a pressure force is exerted on the battery cells in the assembled state, the clamping plates each exerting a compressive force in the direction of the opposite clamping plate. This can increase the volume of the battery cells in the longitudinal direction 231 of the battery module 200 be avoided.

Each clamping plate 240 has a layer 245 on which between the clamping plate and the adjacent battery cell 100a is arranged. The layer 245 can thereby a uniform distribution of the pressure of the clamping plate 240 allow on the side surface of the battery cell, so that damage to the side surface of the battery cell can be avoided by a selective pressure load. Thus, in this exemplary embodiment, it is precisely the fact that a clamping plate consisting of steel or another metal does not come into contact with a side face of a battery cell facing the clamping plate.

3A shows a detailed schematic representation of a portion of a battery module in the unassembled state. A surface 246 the layer 245 the clamping plate 240 forms a contact surface 130 with a first side surface 101 the to the clamping plate 240 adjacently arranged battery cell 100 , At the second side surface 102 the battery cell 100 adjoins another battery cell, which for clarity in 3A not shown.

3B shows one of the 3A corresponding representation of a battery module, wherein the clamping plate 240 yourself in 3B in assembled condition. The clamping plate 240 has no curved course, so that the contact surface 130 with the first side surface 101 the battery cell 100 compared to the 3A over the entire first side surface 101 the battery cell 100 runs. The layer 245 and especially the surface 246 the layer 245 allows a uniform pressure distribution of the pressure force 150 on the first side surface 101 the battery cell 100 ,

In the 2 . 3A and 3B is the layer 245 each as an adhesive element on the clamping plate 240 shown, wherein the layer 245 between the clamping plate 240 and the battery cell adjacent to the clamping plate is located.

4A shows a schematic side view of a clamping plate 240 and a battery cell 100a , The clamping plate 240 has a layer 245 on, with the layer 245 the clamping plate 240 wrapped or sheathed and from the clamping plate 240 leaving only a portion for making a mechanical connection with a tension member. In the mechanical connection of the clamping plate with the tension element may be, for example, a welded connection.

4B shows a schematic plan view of a clamping plate 240 and two tension elements 230 , where the clamping plate 240 in a mounted state on the battery cell 100a with the layer 245 is applied.

The layer 245 is with the clamping plate 240 fastened by means of two retaining lugs, wherein the retaining lugs engage in each case through a recess of the clamping plate, so that the layer 245 mechanically with the clamping plate 240 is coupled.

5 shows a schematic representation of a clamping plate 240 with a layer 245 , The layer 245 has a fiber composite 248 and a plastic 247 on, wherein the fiber composite material as the outer jacket or coating of the layer 245 is shown and the plastic 247 wrapped as the core of the layer.

The layer 245 has a transverse direction 241 the clamping plate 240 tapered cross section, that is, a first thickness 249a the layer in the longitudinal direction of the battery module is greater than a second thickness 249b the layer also in the longitudinal direction of the battery module. The thickness of the layer 245 can in particular, starting from an edge region of the clamping plate 240 in the transverse direction 241 Remove to the middle of the clamping plate and then increase again to the opposite edge of the layer 245 or the clamping plate 240 , This can lead to a surface 246 the layer has a larger radius of curvature than the clamping plate 240 does. Thus, especially at the beginning of an assembly process, an enlarged contact surface with a on the surface 246 be created adjacent battery cell.

Plastic 247 may be plastically more deformable in this embodiment than the fiber composite 248 so that the entire layer 245 is plastically deformable and thus the surface 246 can adapt to a side surface of an adjacent battery cell or to the contour of this side surface, so that a uniform pressure distribution takes place on the adjacent battery cell.

In other words, thus provides the battery module as described above, a combination of optimal pressure distribution, weight saving and production-compliant welding of the clamping plates with the tension elements, however, as an alternative to the weld also a screw or other mechanically coupling or fixing connection between the clamping plate and the Tensile elements is possible. The clamping plates may consist of a pre-formed and preformed spring plate, which is designed for a maximum spring force of, for example, 15 kN. The clamping plate can be embedded in a fiber composite or in a fiber composite material, so that the fibers form a fabric or a knit, which is located between the clamping plate and a battery cell adjacent to the clamping plate. By the fiber composite material, a uniform pressure distribution in the tensioned or mounted state of the clamping plate can be achieved. This can also be achieved in that the fiber composite material directs the compressive forces in the transverse direction of the clamping plate in the edge regions of the clamping plate and the adjacent battery cell.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 102009000660 A1 [0004]

Claims (11)

Battery module ( 200 ), comprising: a tension member ( 230 ); a clamping plate ( 240 ); and a plurality of battery cells ( 100 ); the tension element ( 230 ) and the clamping plate ( 240 ) are executed, in a mounted state, the battery cells ( 100 ) to include; the clamping plate ( 240 ) in an initial state with respect to the battery cells ( 100 ) has a convex shape and is executed, in the mounted state, a pressing force ( 150 ) on the plurality of battery cells ( 100 ) in a direction along a longitudinal direction ( 231 ) of the battery module ( 200 ) exercise; characterized in that the clamping plate ( 240 ) a layer ( 245 ), which is executed, in the mounted state, the pressing force ( 150 ) on a contact surface ( 130 ) of the layer ( 245 ) with one to the clamping plate ( 240 ) adjacent battery cell ( 100A ) to distribute. Battery module ( 200 ) according to claim 1, wherein the layer ( 245 ) a fiber composite ( 248 ) having. Battery module ( 200 ) according to claim 2, wherein the layer ( 245 ) a plastic ( 247 ) having; and wherein the fiber composite ( 248 ) the plastic ( 247 ) surrounds. Battery module ( 200 ) according to claim 3, wherein the plastic ( 247 ) comprises a polypropylene. Battery module ( 200 ) according to any one of the preceding claims, wherein the layer ( 245 ) is designed electrically insulating. Battery module ( 200 ) according to any one of the preceding claims, wherein the layer ( 245 ) in a direction transverse to the longitudinal direction ( 231 ) extending transverse direction ( 241 ) of the battery module ( 200 ) has a tapered cross-section at least in sections. Battery module ( 200 ) according to any one of the preceding claims, wherein each battery cell ( 100 ) of the plurality of battery cells ( 100 ) is a rechargeable battery. Battery module ( 200 ) according to claim 7, wherein the rechargeable battery is a lithium-ion cell. Battery module according to claim 8, wherein the battery cells ( 100 ) are formed prismatic. Battery unit ( 300 ) for an electrical engine, comprising a plurality of battery modules ( 200 ) according to one of claims 1 to 9. Battery unit ( 300 ) according to claim 10, wherein the battery modules ( 200 ) are prismatic in an assembled state.

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