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

Abstract

The present invention relates to a battery module (10) for an electrical energy storage device (12) of a motor vehicle, comprising a plurality of energy storage elements (14), wherein an intermediate plate (16) made 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) can be supported against one another via this intermediate plate (16), which is deformable when an electrical voltage is applied.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of motor vehicles. In particular, 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 compressive force to ensure uniform contact between solid interfaces of the electrical energy storage device, in particular its battery module. The respective interface can be an interface between an anode and a solid-state electrolyte or between a cathode and a solid-state electrolyte. In anode-less versions of the energy storage device, in particular the battery module, the said compressive force can cause lithium creep diffusion onto an anode-less current collector. This can enable targeted deposition of lithium metal on the anode current collector. In the prior art, pressure plates with spring force or a fixed spacer load can be used to generate the compressive force sufficient to enable stable charging and / or discharging behavior.These compression plates can typically be made of thick metal plates such as stainless steel or aluminum, for example, with metal fasteners to hold the compression plates in place. State-of-the-art compression plates are typically heavy and cumbersome. This can significantly impact the energy density gains expected from the adoption of solid-state battery chemistry. Furthermore, current compression plate designs can create a stress concentration gradient, where the battery cells closest to the compression plates are subjected to a greater compression force than the battery cells in the center. In other words, an uneven distribution of the compression force can occur. This unevenly distributed force can lead to uneven degradation of the battery cell and battery cell assembly, posing a potential safety hazard. 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 and a corresponding electrical energy storage device for a motor vehicle, by means of which a desired compression force in the battery module can be realized in a particularly advantageous manner.

[0004] This object is achieved by a battery module for an electrical energy storage device of a motor vehicle and 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. The motor vehicle is preferably designed as a passenger car. The motor vehicle is preferably a battery-electric vehicle (BEV) or a hybrid vehicle, in particular a plug-in hybrid vehicle (PHEV). The energy storage device can be an accumulator or a battery, which can also be referred to as a storage battery. The battery is preferably designed as a solid-state battery.

[0006] The battery module comprises a plurality of energy storage elements, preferably designed as storage cells. The storage cells can be referred to as battery cells. Therefore, the battery module can also be referred to as a cell module or cell pack. The battery module is preferably designed as a cell assembly.

[0007] In order to advantageously generate a desired compressive force in the battery module, in particular in the energy storage elements, an intermediate plate made of a piezoelectric material and an 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 intermediate plate is arranged between at least two of the energy storage elements. The energy storage elements can in particular support one another at least indirectly or directly via the intermediate plate. In other words, the intermediate plate is capable of exerting a mechanical load, in particular the compressive force, on the respective energy storage element. This means that the intermediate plate is capable of at least partially causing the compressive force.The intermediate plate is capable of deforming, particularly elastically, when an electrical voltage is applied, particularly to the intermediate plate. In other words, the application of the electrical voltage leads to the deformation of the intermediate plate. This means that the intermediate plate is designed as a piezoelectric plate, particularly as a piezoelectric pressure plate.

[0008] The respective energy storage element can change its volume during charging and / or discharging. This can be referred to as "breathing." Since the respective energy storage element can experience this "breathing," the prior art compression plates must ideally be adapted to maintain a sufficient level of compression force required for each stage of a charging and / or discharging process. As previously mentioned, the prior art compression plates can be heavy and cumbersome. Therefore, a lightweight and easy-to-implement method for applying the required compression force over the entire lifetime of the battery may not be possible with the prior art.

[0009] In contrast, the battery module uses a piezoelectric material, in particular an inverse piezoelectric material, and an electrode for the intermediate plate. The piezoelectric or inverse piezoelectric material can be understood as a material that experiences volume expansion when subjected to a current. Therefore, the intermediate plate can serve as a pressure plate, in particular instead of the metal plates commonly used in the prior art. The intermediate plate can therefore be capable of handling the stresses acting on the respective energy storage element. Since the extent of volume expansion of the piezoelectric material depends on the current of an applied electric field, it may be possible to integrate the piezoelectric material in such a way that it "breathes" in response to the volume expansion cycles of the battery module, in particular of a solid-state pack system.This can eliminate the need for mechanically moving parts, such as metal or spring devices or hydraulic presses, as the volumetric expansion of the inverted piezoelectric material allows for precise control of the compression forces applied to each battery cell, minimizing degradation due to force imbalance. The proposed solution has the advantage of being a non-mechanical solution, enabling a simplified, weight-efficient design for the compression of the solid-state battery pack. Eliminating the need for large metal brackets, plates, or rotors to transmit the required compression forces can enable particularly high volumetric energy density in the overall package, while reducing vehicle weight, simplifying the package design, and more.In summary, a concept based on the use of piezoelectric responses to solve the problem of compression forces can be realized through the battery module in question. In other words, the battery module consists of a cell array with individual piezoelectric pressure plates for uniform pressure control and distribution.

[0010] In one embodiment, the energy storage elements and the intermediate plate are arranged in 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 energy storage elements mentioned over an area, in particular over a large area.

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

[0013] In another embodiment, an intermediate plate made of a piezoelectric material and an electrode is arranged between each two adjacent energy storage elements, which can be deformed, in particular elastically, when an electrical voltage is applied.

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

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

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

[0017] A further 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 will become apparent from the following description of preferred embodiments and from the drawings. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned in the following description of the figures and / or illustrated alone in the figures, can be used not only in the respective specified combination, but also in any other combination or alone, without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The novel features and characteristics of the present disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. Like numerals are used throughout the figures to refer to like features and components. Some embodiments of systems and / or methods according to embodiments of the present subject matter are described below, by way of example only, and with reference to the accompanying figures.

[0020] The drawings show in: Fig. 1 is a schematic side view of an embodiment of a battery module; and Fig. 2 a schematic side view of an intermediate plate of an embodiment of a battery module; and Fig. 3 a schematic plan view of an embodiment of a battery module.

[0021] In the figures, identical elements or elements with the same function are identified by the same reference numerals. DETAILED DESCRIPTION

[0022] Throughout this document, the word "exemplary" is used 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.

[0023] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will be described in detail below. It should be understood, however, that the disclosure is not intended to limit the disclosure to the particular forms disclosed; on the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0024] The terms "comprises," "including," or other variations thereof are intended to cover non-exclusive inclusion, such that an assembly, device, or method comprising a list of components or steps not only includes those components or steps, but may also include other components or steps not expressly listed or included in such assembly, device, or method. In other words, one or more elements in a system or device preceded by the word "comprises" or "comprise" do not, without further limitation, exclude the presence of other elements or additional elements in the system or method.

[0025] In the following detailed description of the embodiment of the present disclosure, reference is made to the accompanying drawings, which form a part of this disclosure, 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 one 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.

[0026] Fig. 1 shows a schematic side view according to one embodiment of a battery module 10 for an electrical energy storage device 12 of a motor vehicle. The motor vehicle is preferably operated at least partially electrically or fully electrically. Therefore, the motor vehicle can have at least one electric motor. The electric motor is preferably supplied with energy by the electrical energy storage device 12, in particular by the battery module 10. The electrical energy storage device 12 is designed, for example, as a battery, in particular as a high-voltage battery. The battery module 10 comprises a plurality of energy storage elements 14. The energy storage elements 14 are preferably cells, which can also be referred to as battery cells.

[0027] In order to advantageously realize a desired pressure force level in the battery module 10, at least one intermediate plate 16 made of a piezoelectric material 18 and an electrode 38 is arranged between at least two of the energy storage elements 14. In the Fig. In the example shown in Figure 1, an intermediate plate 16 formed from the piezoelectric material 18 and an electrode 38 are arranged between two adjacent energy storage elements 14. This means that the battery module 10 comprises a plurality of intermediate plates 16, with one of the intermediate plates being arranged between two adjacent energy storage elements 14. The adjacent energy storage elements 14, in particular, can be supported against one another via the respective intermediate plate 16, which can deform when an electrical voltage is applied. Thus, the respective intermediate plate 16 can react to a respective change in volume of the respective energy storage element 14 by charging and / or discharging. This ensures a desired level of compression force in the battery module 10, in particular in the aforementioned energy storage elements 14.Pressure plates made of mechanically movable parts, such as metal mounts or spring mounts, are known from the prior art. The intermediate plates 16 can serve as pressure plates instead of the pressure plates of the prior art and can be mounted between the individual cells to manage the stresses acting on the individual cells and pressure plates. The piezoelectric material 18 is, for example, barium titanate (BaTiO3), zinc oxide (ZnO), or polytetrafluoroethylene (PTFE), which can be constructed in a single layer or in multiple layers from polymer or metal plates.

[0028] In the Fig. In the embodiment shown in Figure 1, the energy storage elements 14 and the intermediate plates 16 are arranged along a direction 20, in particular opposite one another. In other words, the battery module 10 is designed as a cell assembly. Fig. 1 therefore shows a side view of the said cell cluster.

[0029] Fig. 2 shows a schematic side view of a respective intermediate plate 16. In the example, the respective intermediate plate 16 is in planar, in particular direct, contact with at least one of the energy storage elements 14. As in Fig. 1 and Fig. 2, the respective intermediate plate 16 is in contact, in particular direct contact, with the adjacent energy storage elements 14 via a respective region 22, 24. This means that the intermediate plate 16 has a first region 22 and a second region 24. Via the respective region 22, 24, the respective intermediate plate 16 is in direct contact with one of the two energy storage elements 14, between which the intermediate plate 16 is arranged. In particular, the respective region 22, 24 is a large surface of the intermediate plate 16. For example, at least one of the regions 22, 24 faces an electrode of the respective energy storage element 14. The respective intermediate plate 16 comprises, for example, one piezoelectric plate 26 or several piezoelectric plates 26 and one electrode 38 or several electrodes 38.

[0030] In the Fig. In the embodiment shown in Figure 1, the wall thickness 28 of each intermediate plate 16 is thinner than the respective energy storage element 14. This means that each intermediate plate 16 can be made very thin, for example, from several tens of micrometers to several tens of millimeters. By using thinner compression plates or intermediate plates 16 between the cells, a more even distribution of forces between the cells can be achieved. The degree of pressure or tension of the individual intermediate plates 16 can be monitored and differentiated depending on the actual forces "sensed" by the individual cells in order to maximize cell performance.

[0031] In the Fig. In the embodiment shown in Figure 1, the energy storage elements 14, in particular the intermediate plates 16, are arranged between two end plates made of a different material than the respective intermediate plate 16, in particular of a different material than the piezoelectric material 18. This means that the respective end plate 30, 32 is made of a non-piezoelectric material, such as aluminum or stainless steel. Preferably, the energy storage elements 14, in particular the cell array, are enclosed by the end plates 30, 32 at both ends of the battery module 10, in particular the cell array.

[0032] The energy storage elements 14 are preferably connected in a force-fitting manner by the end plates 30, 32. In other words, the energy storage elements 14 are clamped together via the end plates 30, 32. Thus, the energy storage elements 14, in particular the cell array, can be fixed to a specific compressive force by the end plates 30, 32, for example, similar to a conventional lithium-ion battery module. Therefore, the respective end plate 30, 32 can also be referred to as a side plate or compression plate. The end plates 30, 32 preferably have good parallelism, ensuring uniform compression across the entire surface of the battery cell, since uneven forces can cause lithium plating, parasitic reactions, loss of conductivity (power), etc.

[0033] The end plates 30, 32 are preferably made of metal. Therefore, the respective end plate 30, 32 can also be referred to as a metal plate or metal pressure plate.

[0034] Fig. shows an embodiment of the battery module 10 in a schematic plan view. In other words: Fig. 3 shows a top view of the cell array in question. As shown in Fig. As shown in Figure 3, the end plates 30, 32 may be part of a housing that surrounds the energy storage elements 14, and in particular the intermediate plate 16. Therefore, the housing may include two side plates 34, 36, which may be made of metal. Therefore, the side plates 34, 36, together with the first end plate 30 and the second end plate 32, may also be referred to as metal side plates. Reference symbol 10 Battery module 12 energy storage units 14 energy storage elements / battery cells 16 Intermediate plate 18 piezoelectric material 20 direction 22 first area 24 second area 26 piezoelectric plate 28 wall thickness 30 first end plate 32 second end plate 34 first side plate 36 second side plate 38 Electrode

Claims

[1] Battery module (10) for an electrical energy storage device (12) of a motor vehicle, with a plurality of energy storage elements (14), characterized by that an intermediate plate (16) made 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) can be supported against one another via this intermediate plate (16), which is deformable when an electrical voltage is applied. [2] Battery module (10) according to claim 1, characterized by that the energy storage elements (14) and the intermediate plate (16) are arranged along one direction (20). [3] Battery module (10) according to claim 1 or 2, characterized by that the intermediate plate (16) is in contact with at least one of the energy storage elements (14) over an area (22, 24) [4] Battery module (10) according to one of claims 1 to 3, characterized bythat a wall thickness (28) of the intermediate plate (16) is thinner than the respective energy storage element (14). [5] Battery module (10) according to one of claims 1 to 4, characterized by that between each two adjacent energy storage elements (14) a respective intermediate plate (16) made of a piezoelectric material (18) and an electrode (28) is arranged, wherein the respective intermediate plate (16) is deformable when an electrical voltage is applied. [6] Battery module (10) according to one of claims 1 to 5, characterized by that the energy storage elements (14) are arranged between two end plates (30, 32) which are made of a different material than the intermediate plate (16). [7] Battery module (10) according to one of claims 1 to 6, characterized by that the energy storage elements (14) are subjected to force by the end plates (30, 32). [8] Battery module (10) according to one of claims 1 to 7, characterized bythat the end plates (30, 32) are made of metal. [9] Electrical energy storage device (12) for a motor vehicle, comprising at least the battery module (10) according to one of claims 1 to 8.

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