Energy storage module and method for manufacturing an energy storage module

Abstract

Energy storage module for a device for supplying power, in particular for a motor vehicle, comprising several storage cells arranged in a housing and combined to form a cell module, wherein the energy storage module further comprises an element (1) for thermal insulation and absorption of deformation energy, wherein at least a part of the element (1) for thermal insulation and absorption of deformation energy consists of expanded polypropylene, characterized in that the element (1) for thermal insulation and absorption of deformation energy is arranged at least on a part of the inside of the housing between the cell module and the housing, wherein pockets for the insertion of further components are provided in the element (1) for thermal insulation and absorption of deformation energy.

Description

[0001] The invention relates to an energy storage module for a power supply device, in particular for a motor vehicle, comprising several storage cells arranged in a housing and combined to form a cell module. The invention further relates to a method for manufacturing an energy storage module.

[0002] A device commonly referred to as a battery, used to supply power to a motor vehicle, typically employs multiple energy storage modules to power the vehicle, for example, electric or hybrid vehicles. Each energy storage module usually contains several cell modules, typically consisting of multiple stacked prismatic storage cells. The individual storage cells contain the electrochemical cells of the battery. The stack of individual storage cells is mechanically clamped together to form the energy storage module via an end plate (also called a pressure plate) and tension elements. The cell module is then inserted into a housing, which is subsequently connected to the motor vehicle.

[0003] Energy storage systems, particularly those used in motor vehicles, are subjected to high stresses, such as intense heat from surrounding components like the vehicle's exhaust system, heat radiation from the heated road surface, and mechanical impact, especially during a vehicle crash. Furthermore, heat is generated within the energy storage system itself, which is dissipated by the use of cooling elements. To protect energy storage modules from heat exposure, it is common practice to incorporate heat-dissipating plates, particularly on the underside of the module, or thermal insulation layers around the module, or suitable cooling elements. Such designs have the disadvantage of being complex to install, requiring additional installation space, and significantly increasing the overall weight of the energy storage module and, consequently, the vehicle.For thermal insulation of an energy storage module, protective layers made of polyester material are used, for example. These provide a certain degree of thermal insulation for the energy storage module, but they cannot protect it from deformation energies, i.e., mechanical impacts such as those occurring in a vehicle crash, and thus cannot compensate for, absorb, or dissipate deformation energies to prevent damage to the energy storage module. To provide sufficient protection for the energy storage module against deformation energies, encasing it in an injection-molded plastic shell is therefore proposed. However, the wall thickness of such injection-molded parts is limited by the manufacturing process, meaning that a certain maximum wall thickness cannot be exceeded.However, these wall thicknesses are generally insufficient to adequately compensate for deformation energies, such as those occurring in a vehicle crash. Therefore, additional bracing is required to provide the necessary stability. This, along with the high technical complexity and intricate assembly of such an energy storage module, results in high unit costs. Furthermore, the necessary injection molds are also expensive, which further negatively impacts the production costs of the energy storage module.Furthermore, it has been shown that even injection-molded shells stabilized by space-intensive bracing often lack sufficient stability, especially under high mechanical stress, causing the bracing to break and the deformation energy to be transferred directly to the energy storage module, inevitably leading to its destruction.

[0004] DE 197 52 755 A1 discloses the use of thermoplastic particle foam for heat protection covers for lead-acid batteries in the engine compartments of motor vehicles. The heat protection cover is characterized by a box-like structure adapted to the circumference of the lead-acid battery. This box-like structure is made of high-density EPP.

[0005] DE 693 31 980 T2 shows a vehicle battery with a battery housing for holding battery fluid and a heat shield, which is formed in one piece or from two interconnected pieces and is substantially fixed to the battery housing, so that the battery housing and the heat shield form a substantially uniform rigid arrangement.

[0006] DE 20 2005 010 708 U1 shows a housing for accumulator batteries. The housing has at least a partial foam structure.

[0007] DE 10 2010 009 063 A1 discloses a holding element for an electrical energy storage device for motor vehicles with at least one energy storage cell. The holding element is at least partially made of a thermally conductive material. Furthermore, an electrical energy storage device for motor vehicles with at least one energy storage cell and at least one holding element is disclosed.

[0008] DE 10 2009 040 598 A1 discloses a battery module for a vehicle. The battery module comprises several battery packs, each with several individual cells, and is essentially arranged in a closed housing. The battery module includes at least one impact energy-absorbing element, which is arranged on and / or in the housing.

[0009] The object of the present invention is to provide a space-saving energy storage module characterized by very good thermal insulation properties and excellent stability against deformation energy (mechanical stress). Furthermore, the energy storage module should possess sufficient electrolyte stability. It is also an object of the present invention to provide a method for manufacturing an energy storage module that is characterized by a simple and cost-effective process, requires only minimal manufacturing effort, and thus allows for simple and cost-effective production of the energy storage module.

[0010] The problems are solved by the combinations of features in the independent claims. The dependent claims describe advantageous embodiments of the invention.

[0011] The problem is thus solved by an energy storage module for a power supply device, in particular for a motor vehicle, comprising several storage cells arranged in a housing and grouped into a cell module, wherein the energy storage module further includes an element for thermal insulation and absorption of deformation energy. At least part of the element for thermal insulation and absorption of deformation energy consists of expanded polypropylene. A cell module within the meaning of the invention comprises at least one series of stacked storage cells, which may be tensioned together via end plates and tension elements. Further conventional structural components can complete the cell module.Expanded polypropylene is a material characterized by its very low weight, high robustness, abrasion resistance, and electrolyte stability, making it particularly suitable for use in energy storage modules due to these positive properties. Furthermore, expanded polypropylene also exhibits high thermal insulation properties and excellent compressibility. In other words, expanded polypropylene does not conduct ambient heat, heat generated by friction, or radiant heat energy, thus providing sufficient protection against overheating for the energy storage module according to the invention, which includes an element made at least partially of expanded polypropylene.Furthermore, due to its excellent compressibility, expanded polypropylene is ideally suited to compensate for deformation energies, such as those occurring in a vehicle crash, i.e., to absorb and dissipate them, so that the applied mechanical energy, i.e., the crash energy, does not lead to cracking or even destruction of the energy storage module. According to the invention, at least one part of the element for thermal insulation and absorption of deformation energy is made of expanded polypropylene. This part made of expanded polypropylene is preferably a part of the energy storage module according to the invention that is exposed to heat radiation or that is most likely to be affected in the event of a vehicle crash. This depends on the specific structural environment of the energy storage module and can be selected accordingly.Thus, an energy storage module is provided that is characterized by excellent, long-term stability, is protected against overheating, and adequately compensates for deformation energies. The high compressibility of the expanded polypropylene element for thermal insulation and deformation energy absorption further has the advantage that a very thin layer thickness of said element is sufficient to achieve the desired stability, particularly with regard to compensating for crash energy. Therefore, the external dimensions of the energy storage module are only minimally increased, if at all, by integrating said element. Thus, the energy storage module according to the invention is designed to be space-saving.Furthermore, the energy storage module according to the invention has a low weight and is resistant to electrolytes, which is essential in the event of a leak in a storage cell.

[0012] In an advantageous embodiment, the element for thermal insulation and absorption of deformation energy is provided to consist essentially of expanded polypropylene. This maximizes the effects achieved according to the invention.

[0013] According to the invention, the element for thermal insulation and absorption of deformation energy is arranged at least on a portion of the inner surface of the housing, between the cell module and the housing. This internal element, located within the housing and particularly between the housing and the cell module, allows for a particularly efficient structural integration of the protective element with respect to both the cell module and the surrounding housing. This integration of components results in a particularly compact energy storage module.

[0014] A further advantage is that the element for thermal insulation and absorption of deformation energy can be located both on the outside and on the inside of the housing. This is particularly beneficial for energy storage modules subjected to high mechanical stress and those exposed to strong heat radiation, as it achieves exceptionally high stability against the input of deformation energy, while only minimally altering, i.e., increasing, the physical dimensions of the energy storage module.Preferably, the element for thermal insulation and absorption of deformation energy is provided as a negative surface of the inner and / or outer housing surface, as this achieves an excellent fit between the components of the energy storage module according to the invention. This allows the advantageous properties of the expanded polypropylene element, and in particular its thermally insulating and deformation energy-compensating properties, to be utilized to their full potential. Furthermore, in many cases, this eliminates the need for separate fastening of the expanded polypropylene element, since the element typically adheres well to the housing due to its conformity to the individual housing sections.

[0015] According to the invention, the element for thermal insulation and absorption of deformation energy is provided with recesses for inserting or attaching further components. These recesses are pockets or, more generally, depressions into which, for example, electrical connections, separators, fasteners, and other components can be integrated into the energy storage module according to the invention. This is advantageous because integrating such components into these recesses allows the physical dimensions of the energy storage module to be kept as small as possible and, in particular, prevents them from being increased.

[0016] Furthermore, according to the invention, a method for manufacturing an energy storage module for a power supply device, in particular for a motor vehicle, is provided, comprising the steps of providing a housing for the energy storage module, manufacturing an element for thermal insulation and absorption of deformation energy by producing a negative impression of the inner surface of the housing made of expanded polypropylene, attaching the corresponding element for thermal insulation and absorption of deformation energy inside the housing, providing a cell module comprising several storage cells and other conventional components, and inserting the cell module into the housing.By providing the element for thermal insulation and absorption of deformation energy in the form of a negative imprint of the inner surface of the housing, an element made of expanded polypropylene is provided that can be easily attached to the housing of the energy storage module according to the invention, which can be manufactured simply, without great technical effort depending on the individual shape of the housing and which protects the energy storage module in particular from the effects of heat and deformation energy due to its thermally insulating properties and high compressibility.

[0017] To produce a negative surface for the housing, for example, spherical expanded polypropylene with a diameter of approximately 0.5 mm is atomized into a suitably shaped mold, where, under the influence of heat and / or humidity and a vacuum, it spontaneously expands into the designated mold cavities. The individual spheres then fuse together to form a stable material, which can be removed from the mold after it has cooled.

[0018] The expanded polypropylene element can be most easily attached to the outer surface of the housing by slipping the expanded polypropylene jacket over it or by directly applying a layer of polypropylene material of the appropriate thickness, which will then be expanded. If the expanded polypropylene element is intended to be installed inside the housing, preferably between the housing and the cell module, separate fastening is often unnecessary, as the virtually exact replication of the housing's inner surface ensures sufficient stabilization of the expanded polypropylene element. If fastening is required, it can be achieved in the usual way, for example, by applying thermal energy and, if necessary, pressing the components to be joined together.

[0019] Because expanded polypropylene is used as the essential material of the element for thermal insulation and absorption of deformation energy, and thus the invention eliminates the need for conventional injection-molded parts which are produced using expensive and complex injection molding machines, the costs of the manufacturing process according to the invention, and therefore those of the energy storage module, are also low.

[0020] According to an exemplary embodiment of the process for manufacturing an energy storage module with an element for thermal insulation and absorption of deformation energy in the form of a negative surface of the inner surface of a housing, the corresponding housing, of which a negative mold made of expanded polypropylene has been created beforehand, is first fixed on a workbench. The expanded polypropylene material in the form of the negative surface of the inner surface of the housing is inserted into the housing. Subsequently, the intended cell modules are inserted.

[0021] According to the invention, the manufacturing of an element for thermal insulation and absorption of deformation energy includes providing recesses in the element for the subsequent insertion of further components. As already described, recesses are pockets or, more generally, depressions into which further components, such as electrical connections, conductors, fasteners, and other components, can be integrated into the energy storage module according to the invention.

[0022] The advantageous embodiments described within the framework of the energy storage module according to the invention find correspondingly advantageous application within the framework of the method according to the invention for manufacturing the energy storage module.

[0023] Thus, according to the invention, a space-saving energy storage module is provided, characterized by excellent stability, particularly with regard to applied heat radiation or thermal energy in general, i.e., by thermally insulating properties, electrolyte stability, and stability with respect to applied deformation energies, such as crash energy. Compared to conventional energy storage modules, this module has a low weight, making it particularly suitable for lightweight vehicles. The method provided according to the invention allows for the cost-effective and simple provision of an energy storage module with outstanding stability properties, without requiring significant technical or logistical effort. This module is easy to implement and can be customized, thus reducing the manufacturing costs of the energy storage module and, consequently, its overall cost.Essential to the present invention is the use of expanded polypropylene for the integrated element for thermal insulation and absorption of deformation energy.

[0024] The invention is explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a side view of an element formed as a negative surface of a housing for an energy storage module made of expanded polypropylene for thermal insulation and absorption of deformation energy according to a first embodiment.

[0025] The invention will now be described in more detail using the following examples. Fig. 1 explained in more detail.

[0026] In Fig.Figure 1 shows a side view of an element 1 formed as a negative surface of a housing (not shown) for an energy storage module (not shown) made of expanded polypropylene for thermal insulation and absorption of deformation energy according to a first embodiment of the invention. The element 1 has mounting points 10 for storage cells to be arranged in series or mounting points 10 for one or more storage cell modules (not shown), as well as pockets 11 for receiving, for example, electrical connection ports. Due to its design as a negative surface of the housing made of expanded polypropylene, i.e., due to the essentially exact reproduction of the inner surface of the housing, the element 1 made of expanded polypropylene fits precisely into the housing and can therefore be easily inserted into the housing without requiring any further fastening.This is advantageous from a manufacturing perspective, as it eliminates the need for additional fasteners during the production of the energy storage module. The layer thickness 12 of element 1 made of expanded polypropylene is small, so that overall there is essentially no increase in the overall size of the energy storage module, and the energy storage module nevertheless retains sufficient stability against mechanical stress due to the excellent deformation energy-compensating properties of expanded polypropylene. Compared to conventional energy storage modules, especially those with metal heat-dissipating plates, the energy storage module according to the invention has a lower weight while offering excellent thermal insulation properties, making it particularly suitable for use in lightweight vehicle construction. Reference symbol list 1 element for thermal insulation and absorption of deformation energy 10 mounting points 11 pockets 12 layer thickness

Claims

Energy storage module for a device for supplying power, in particular for a motor vehicle, comprising several storage cells arranged in a housing and combined to form a cell module, wherein the energy storage module further comprises an element (1) for thermal insulation and absorption of deformation energy, wherein at least a part of the element (1) for thermal insulation and absorption of deformation energy consists of expanded polypropylene, characterized in that the element (1) for thermal insulation and absorption of deformation energy is arranged at least on a part of the inside of the housing between the cell module and the housing, wherein pockets for the insertion of further components are provided in the element (1) for thermal insulation and absorption of deformation energy. Energy storage module according to claim 1, characterized in that the element (1) for thermal insulation and absorption of deformation energy consists essentially of expanded polypropylene. Energy storage module according to claim 1 or 2, characterized in that the element (1) for thermal insulation and absorption of deformation energy surrounds the housing of the energy storage module at least partially, in particular completely. A method for manufacturing an energy storage module for a power supply device, in particular for a motor vehicle, comprising the steps of: - providing a housing for the energy storage module, - manufacturing an element (1) for thermal insulation and absorption of deformation energy by producing a negative mold of the housing's inner surface from expanded polypropylene, - attaching the corresponding element (1) for thermal insulation and absorption of deformation energy inside the housing, - providing a cell module comprising several storage cells, and - inserting the cell module into the housing, - wherein the manufacturing of the element (1) for thermal insulation and absorption of deformation energy comprises providing pockets in the element for the subsequent insertion of further components.

Images