A battery module for an electrical energy storage device of a motor vehicle and an electrical energy storage device for a motor vehicle

Abstract

A battery module 10 for an electrical energy storage device 12 of a motor vehicle comprises several energy storage elements 14, wherein an intermediate plate 16 formed of a piezoelectric material 18 and an electrode 38 is arranged between at least two of the energy storage elements. The energy storage elements are supported against one another via an intermediate plate, which is capable of being deformed when an electrical voltage is applied. A wall thickness 28 of the intermediate plates is preferably thinner than the energy storage elements. Two end plates 30,32 made from a different material than the intermediate plate may be provided, which may be made of metal and used to exert force on the energy storage elements.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of automobiles. More specifically, the present invention relates to a battery module for an electrical energy storage device of a motor vehicle. Furthermore, the present invention relates to a corresponding energy storage device for a motor vehicle. BACKGROUND INFORMATION

[0002] Electrical energy storage devices such as solid state batteries may require a compression force to help, in particular to ensure, conformal contact between solid interfaces of the electrical energy storage device, in particular of its battery module. The said respective interface may be an interface between an anode and a solid-state electrolyte or between a cathode and a solid-state electrolyte. In anode-less designs of the energy storage device, in particular of the battery module, the said compression force may induce lithium creep diffusion onto an anode-less current collector. As a result, a targeted deposition of lithium metal may be enabled onto the anode current collector. In the state of the art compression plates with either spring loads or fixed distance loads may be used in order to impart the said compression force sufficient for facilitating stable charge behaviors and / or discharge behaviors. The said compression plates may usually be made up of thick metal plates such as stainless steel or aluminum, for example with metal fixtures to hold the compression plates in place. The said compression plates of the state of the art may usually be heavy and cumbersome. This may detract significantly from the overall energy density gain that is expected from adopting the solid-state battery chemistry. Furthermore, current compression plate designs may create a stress concentration gradient, where the battery cells closest to the compression plates may experience a greater compression force compared to the battery cells in the middle. In other words, there may be an uneven distribution of the compression force. The uneven imparted force may cause an uneven degradation of the battery cell and a battery cell array as well as being a potential safety risk. SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide a battery module for an electrical energy storage device of a motor vehicle as well as a corresponding electrical energy storage device for a motor vehicle, by which a desired compression force in the battery module can be realized in a particularly advantageous manner.

[0004] This object is solved by a battery module for an electrical energy storage device of a motor vehicle as well as a corresponding electrical energy storage device for a motor vehicle according to the independent claims. Advantageous embodiments are presented in the dependent claims.

[0005] One aspect of the present invention relates to a battery module for an electrical energy storage device of a motor vehicle. Preferably, the motor vehicle is designed as a passenger car. Preferably, the motor vehicle is a battery electric vehicle (BEV) or a hybrid vehicle, in particular a plugin hybrid vehicle (PHEV). The energy storage device may be understood as an accumulator or a battery, respectively, which may be referred to as storage battery. Preferably, the battery is designed as a solid-state battery.

[0006] The battery module comprises several energy storage elements, which are preferably designed as storage cells. The storage cells may be referred to as battery cells. Therefore, the battery module may be referred to as cell module or cell pack. Preferably, the battery module is designed as a cell array.

[0007] In particular, to create a desired compression force in the battery module, in particular in the energy storage elements, in an advantageous manner, an intermediate plate formed of a piezoelectric material and electrode is arranged between at least two of the energy storage elements. In other words, the battery module comprises at least one intermediate plate made of a piezoelectric material and an electrode, wherein the said intermediate plate is located at least between two of the said energy storage elements. The energy storage elements are capable of being supported, in particular at least indirectly or directly, against one another via the said intermediate plate. In other words, the said intermediate plate is capable of applying a mechanical load, in particular the said compression force, to the respective energy storage element. This means, that the said intermediate plate is capable of causing the said compression force at least partially. The said intermediate plate is capable of being, in particular elastically, deformed when an electrical voltage is applied, in particular to the said intermediate plate. In other words, applying the said electrical voltage leads to the deformation of the said intermediate plate. This means, that the said intermediate plate is designed as a piezoelectric plate, in particular as a piezoelectric pressure plate.

[0008] The respective energy storage element may change its volume during charge and / or discharge. This may be referred to as “breathing”. Because the respective energy storage element may undergo the said “breathing”, the compression plates of the state of the art will ideally have to be adjusted in order to maintain a sufficient compression force level required for each stage of a charging process and / or a discharging process. As already mentioned, the compression plates of the state of the art may be heavy and cumbersome. Therefore, a lightweight and easy to implement mode to apply the required compression force over a battery life may not be possible in the state of the art.

[0009] In contrast, in the said battery module a piezoelectric, in particular converse piezoelectric, material and an electrode is used for the said intermediate plate. The piezoelectric or the converse piezoelectric material, respectively, may be understood as a material that undergoes volume expansion when applied with a current. Therefore, the said intermediate plate may serve as a compression plate, in particular instead of the current metal plates of the state of the art. Therefore, the said intermediate plate may be capable of managing stresses applied to the respective energy storage element. Because of an extent of volumetric expansion of the piezoelectric material is dependent on current of an applied electric field, it may become possible to integrate the piezoelectric material to “breathe” in response to the volume expansion cycles of the battery module, in particular of a solid-state pack system. This may negate a need for mechanically moving parts, for example metal fixtures or spring fixtures or hydraulic presses, as the volume expansion of the converse piezoelectric material will allow precise control of the compression forces applied to the respective battery cell, thereby minimizing degradation as a result of force imbalance. The suggested solution has the advantage that it may be a non-mechanical solution that will enable a simplified, weight-efficient design for imparting compression of the solid-state battery pack. The removal of large metal fixtures, plates, or rotors to impart the necessary compression forces may allow a particularly higher volumetric energy density in overall pack level, while also reducing vehicle weight, simpler pack design, et cetera. In summary, a concept based on using piezoelectric responses to solve the issue of compression forces can be realized by the said battery module. In other words, the said battery module comprises a cell array design with individual piezoelectric pressure plates for uniform pressure control and distribution.

[0010] According to an embodiment the energy storage elements and the intermediate plate are arranged along one direction, in particular against each other.

[0011] In another embodiment the intermediate plate is in, in particular direct, contact with at least one of the said energy storage elements over an area, in particular over a large surface.

[0012] In another embodiment, a wall thickness of the said intermediate plate may be thinner than the respective energy storage element.

[0013] In another embodiment, a respective intermediate plate formed of a piezoelectric material and an electrode is arranged between each two adjacent ones of the energy storage elements, wherein the said respective intermediate plate is capable of being, in particular elastically, deformed when an electrical voltage is applied.

[0014] In another embodiment, the energy storage elements are arranged between two end plates, which are made of a material different from the intermediate plate.

[0015] In another embodiment, the energy storage elements are force-loaded by the end plates.

[0016] In another embodiment, the said end plates are made of metal.

[0017] Another aspect of the present invention relates to an electrical energy storage device for a motor vehicle, comprising at least the battery module according to the first aspect of the invention. Advantageous embodiments of the electrical energy storage device are to be regarded as advantageous embodiments of the battery module and vice versa.

[0018] Further advantages, features, and details of the present invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The novel features and characteristic of the present disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0020] The drawings show in:

[0021] Fig. 1 a schematic side view of an embodiment of a battery module; and

[0022] Fig. 2 a schematic side view of an intermediate plate of an embodiment of a battery module; and

[0023] Fig. 3 a schematic top view of an embodiment of a battery module.

[0024] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0025] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0026] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0027] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0028] In the following detailed description of the embodiment of the present disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0029] Fig. 1 shows a schematic side view according to an embodiment of a battery module 10 for an electrical energy storage device 12 of a motor vehicle. The motor vehicle is preferably at least in part electrically operated or full electrically operated. Therefore, the motor vehicle may comprise at least one electric motor. Preferably, the electric motor is supplied with energy by the electrical energy storage device 12, in particular by the battery module 10. For example, the electrical energy storage device 12 is designed as a battery, in particular a high-voltage battery. The battery module 10 comprises several energy storage elements 14. Preferably, the energy storage elements 14 are cells, which may be referred to as battery cells.

[0030] In order to realize a desired compression force level in the battery module 10 in an advantageous manner, at least one intermediate plate 16 formed of a piezoelectric material 18 and an electrode 38 is arranged between at least two of the energy storage elements 14. In the example shown in Fig. 1 a respective intermediate plate 16 formed of the piezoelectric material 18 and an electrode 38 is arranged between each two adjacent ones of the energy storage elements 14. This means, that the battery module 10 comprises several intermediate plates 16, wherein each respective one of the intermediate plates is arranged between two adjacent ones of the energy storage elements 14. The, in particular adjacent, energy storage elements 14 are capable of being supported against one another via the respective intermediate plate 16, which is capable of being deformed when an electrical voltage is applied. Therefore, the respective intermediate plate 16 can react to a respective volume change of the respective energy storage element 14 caused by charging and / or discharging. As a result, a desired level of the compression force in the battery module 10, in particular in the said energy storage elements 14, may be ensured. Pressure plates made of mechanically moving parts, for example metal fixtures or spring fixtures, are known from the state of the art. The intermediate plates 16 may serve as compression plates instead of the pressure plates of the state of the art and may be fitted between each cell to manage stresses applied to each cell and pressure plates. For example, the piezoelectric material 18 is barium titanate (BaTiOs), zinc oxide (ZnO), or polytetrafluoroethylene (PTFE), which may be a single layer design or a composite multi-layer design consisting of polymer or metal sheets.

[0031] In the embodiment shown in Fig. 1 the energy storage elements 14 and the intermediate plates 16 are arranged along one direction 20, in particular against each other. In other words, is the battery module 10 designed as a cell array. Therefore, Fig. 1 shows a side view of the said cell array.

[0032] Fig. 2 shows a schematic side view of a respective ones of the intermediate plates 16. In the example, the respective intermediate plate 16 is in, in particular direct, contact with at least one of the energy storage elements 14 over an area. As shown in Fig. 1 and Fig. 2, the respective intermediate plate 16 is in, in particular direct, contact with the respective adjacent energy storage elements 14 over a respective area 22, 24. This means, that the intermediate plate 16 comprises a first area 22 and a second area 24. Via the said respective area 22, 24 the respective intermediate plate 16 is in direct contact with a respective one of the two energy storage elements 14, between which the said intermediate plate 16 is arranged. In particular, the respective area 22, 24 is a large surface of the intermediate plate 16. For example, at least one of the areas 22, 24 is turned towards an electrode of the respective energy storage element 14. For example, the respective intermediate plate 16 comprises one piezoelectric sheet 26 or several piezoelectric sheets 26 and one electrode 38 or several electrodes 38.

[0033] In the embodiment shown in Fig. 1 a wall thickness 28 of the respective intermediate plate 16 is thinner than the respective energy storage element 14. This means that the respective intermediate plate 16 may be designed very thin such as several tens of microns to tens of millimeters. An implication of thinner compression press plates or intermediate plates 16, respectively, to be disputed between cells may allow a more uniform distribution of forces between the cells. A compressive or expensive extent of individual intermediate plates 16 may be monitored and differentiated depending on the actual forces “felt” by individual cells to maximize cell performance.

[0034] In the embodiment shown in Fig. 1 the energy storage elements 14, in particular the intermediate plates 16, are arranged between two end plates, which are made of a material different from the respective intermediate plate 16, in particular different from the piezoelectric material 18. This means that the respective end plate 30, 32 is made of a material that is a not piezoelectric material such as aluminum or stainless steel. Preferably, the energy storage elements 14, in particular the cell array, is encased by the end plates 30, 32 on both ends of the battery module 10, in particular of the cell array.

[0035] Preferably, the energy storage elements 14 are force-loaded by the end plates 30, 32. In other words, the energy storage elements 14 are braced together via the end plates 30, 32. Thus the energy storage elements 14, in particular the cell array, may be fixed to a specified compression force by the end plates 30, 32, for example much like a conventional lithium-ion battery module design. Therefore, the respective end plate 30, 32 may also be referred to as side plate or compression plate. Preferably, the end plates 30, 32 have a good parallelism so that there is uniform compression throughout an entire battery cell surface as non-uniform forces may be the cause for lithium plating, parasitic reactions, loss of conductivity (performance), et cetera.

[0036] Preferably, the end plates 30, 32 are made of metal. Therefore, the respective end plate 30, 32 may also be referred to as metal plate or metal compression plate.

[0037] Fig. 3 shows an embodiment of the battery module 10 in a schematic top view. In other words, Fig. 3 shows a top view of the said cell array. As shown in Fig. 3 the end plates 30, 32 may be part of a housing surrounding the energy storage elements 14, and in particular the intermediate plate 16. Therefore, the housing may comprise two side plates 34, 36, which may be made of metal. Therefore, the side plates 34, 36 may be also referred to as metal side plate along with the first end plate 30 and the second end plate 32. Signs battery module energy storage device energy storage elements / battery cells intermediate plate piezoelectric material direction first area second area piezoelectric sheet wall thickness first end plate second end plate first side plate second side plate electrode Mercedes-Benz Group AG

Claims

1. A battery module (10) for an electrical energy storage device (12) of a motor vehicle, comprising several energy storage elements (14), characterized in thatan intermediate plate (16) formed of a piezoelectric material (18) and an electrode (38) is arranged between at least two of the energy storage elements (14), wherein the energy storage elements (14) are capable of being supported against one another via the said intermediate plate (16), which is capable of being deformed when an electrical voltage is applied.

2. The battery module (10) according to claim 1, characterized in thatthe energy storage elements (14) and the intermediate plate (16) are arranged along one direction (20).

3. The battery module (10) according to claim 1 or 2, characterized in thatthe intermediate plate (16) is in contact with at least one of the energy storage elements (14) over an area (22, 24)4. The battery module (10) according to any one of claims 1 to 3, characterized in thata wall thickness (28) of the intermediate plate (16) is thinner than the respective energy storage element (14).

5. The battery module (10) according to any one of claims 1 to 4, characterized in thata respective intermediate plate (16) formed of a piezoelectric material (18) and an electrode (28) is arranged between each two adjacent ones of the energy storage elements (14), wherein the said respective intermediate plate (16) is capable of being deformed when an electrical voltage is applied.

6. The battery module (10) according to any one of claims 1 to 5,characterized in thatthe energy storage elements (14) are arranged between two end plates (30, 32), which are made of a material different from the intermediate plate (16).

7. The battery module (10) according to any one of claims 1 to 6, characterized in thatthe energy storage elements (14) are force-loaded by the end plates (30, 32).

8. The battery module (10) according to any one of claims 1 to7, characterized in thatthe end plates (30, 32) are made of metal.

9. An electrical energy storage device (12) for a motor vehicle, comprising at least the battery module (10) according to any one of claims 1 to 8.13

Images