High-voltage battery with at least two adjacent battery modules

Abstract

The invention relates to a high-voltage battery (1) with at least two adjacent battery modules (3) which are electrically contacted with one another, wherein the battery modules (3) each have a module housing (4) which is connected to ground and is less high than individual battery cells (2) of the battery modules (3), and wherein the electrical contact (6) between the battery modules (3) is arranged above the module housing (4). The high-voltage battery according to the invention is characterized in that a plastic element (10) is arranged between the upper edges of the adjacent module housings (4) and the electrical contact (6) between the battery modules (3).

Description

The invention relates to a high-voltage battery having at least two adjacent battery modules of the type defined in more detail in the preamble of claim 1.High-voltage batteries, which are used, for example, in motor vehicles for storing electrical drive energy, are known from the prior art. The terminology of the high-voltage battery is thereby based on the ECE R100 with regard to its definition, according to which components with a minimum voltage of 60 V DC current are referred to as high-voltage components.DE 10 2022 000 465 A1 describes such a battery which is constructed as a stack of individual battery cells. These form a battery module, wherein a plurality of such battery modules are assembled to form the high-voltage battery within a battery housing.WO 2024 / 090 936 A1 describes a refractory bus connection. This is provided with a silicone coating which ceramizes at high temperatures.WO 2024 / 054 098 A1 discloses a further refractory bus connection made of a metal plate. There, insulation is used which forms a chemical compound with the metal plate in order to insulate the structure.DE 10 2012 219 782 A1 describes a battery module. This is designed such that it can be stacked with modules of identical construction.Furthermore, DE 10 2020 200 006 A1 discloses a vehicle battery in which an insulating layer is arranged between the battery modules and a housing cover of a battery housing. In addition, a separating element is provided which galvanically separates the electrical series connection of the battery modules in the event of a thermal event.High-voltage batteries, as are nowadays used for storing electrical energy in electrically driven motor vehicles, are usually embodied in lithium-ion technology. The individual battery cells have a correspondingly high energy density. If, for example, a cell-internal short circuit occurs within one of these individual battery cells, a very large amount of heat can thus be generated. This ensures a correspondingly high quantity of gas within the individual battery cell, which is typically discharged into the environment via an overpressure relief element or burst element in order to relieve the load on the structure. However, this results in a heat input to adjacent cells, as described in the above-mentioned prior art.One of the problems can be that short circuits occur within the battery module as a result of the hot gases and particles from the individual battery cell concerned, for example if the hot gases and particles decompose insulating lacquer layers, so that a short circuit can occur on electrically conductive elements lying comparatively close to one another, for example a cell connector connecting the positive poles of two adjacent battery modules and the module housing lying on ground. Such a short circuit then ensures an additional progress of the thermal event, which should actually be controlled as quickly as possible in order to ensure the safety of the structure.The object of the present invention is to specify an improved high-voltage battery having at least two adjacent battery modules, which is optimized with respect to a possible short circuit in the event of a thermal event.According to the invention, this is achieved by a high-voltage battery having the features in claim 1, and here in particular in the characterizing part of claim 1. Advantageous embodiments and further developments are evident from the dependent claims dependent thereon.The high-voltage battery according to the invention comprises at least two adjacent battery modules which are electrically contacted with one another, that is to say in particular have at least one cell connector which engages across the module as electrical contacting in the region of their current-carrying poles. The battery modules each have a module housing which is grounded and which is typically configured to be less high than the individual battery cells themselves. The module housings are now positioned comparatively close to one another, so that only a small gap remains between them.In the case of a thermal event, it can now occur that the cell connector, i.e. the electrical contact between the battery modules, which according to an advantageous refinement is electrically insulated via a lacquer layer, is damaged. For example, hot gases with glowing and / or abrasive particles can damage the lacquer layer. Subsequently, a short circuit can then occur between the cell connector connected, for example, to the positive pole of one of the battery modules or of both battery modules and the module housings connected to ground. In the case of a thermal event within one of the battery modules, an additional critical region thus arises, which can contribute to the thermal event being developed even further and more quickly, in the worst case over the entire high-voltage battery.In order to remedy this, it is provided according to the invention that a plastic element is arranged between the module housings and the electrical contact between the battery modules.This plastic element can be configured in particular such that it consists of a plastic which melts in the case of a thermal event in the battery modules. The plastic element can be loosely inserted between the two adjacent module housings and the cell connectors during production. In this context, loose means that a certain distance remains, i.e. the plastic element does not have to be pressed into the intermediate space. For example, the plastic element can be a square, square or round rod which, in the typical arrangement, is at a distance of a few tenths of a millimeter from the respective battery modules, so that loose insertion or insertion of the plastic element is possible even within the scope of the usual manufacturing tolerances. The assembly is thus very simple and efficient.In the event of a thermal event, this plastic element then melts and closes the gap between the module housings and optionally between the cell housings of the individual battery cells and the walls of the module housing. In addition, the plastic covers the end faces of the module housings in an insulating manner. This prevents a short circuit from occurring even if the electrically insulating lacquer layer is damaged at the cell connector. The plastic element can thus reliably prevent a short circuit in this region.According to a very advantageous refinement, the plastic element can be realized as a rod or strip made of a suitable plastic material. This can be a solid material or also a foamed material, in order to be able to save weight in this way.The module housing itself can consist, for example, of lateral strips which hold the individual battery cells of the battery module in position. In particular, these can be prismatic individual battery cells with a stable cell housing or a film pouch with frames, which are stacked on top of one another. According to an advantageous refinement, the plastic element then runs in the stacking direction between the battery modules and can be embodied in particular longer than the module housing. It can thus protrude beyond the module housing in the stacking direction in order in this way to reliably isolate all partial regions of the module housing from regions with possible cell connectors in any case.In addition to the above-described configuration of the module housing with lateral elements such as sheet metal strips for fixing the individual battery cells, a trough-shaped module housing in which the individual battery cells are positioned accordingly would also be conceivable.Further advantageous configurations of the high-voltage battery according to the invention also result from the exemplary embodiment which is illustrated in more detail below with reference to the figures.The following are shown: FIG. 1 shows a schematic cross section through a part of a battery module according to the prior art; FIG. 2 shows the construction analogous to the representation in FIG. 1 in an embodiment according to the invention; and FIG. 3 shows a plan view of a possible embodiment of a high-voltage battery according to the invention.In the illustration of FIG. 1, a section of a high-voltage battery according to the prior art, denoted overall by 1, can be seen in a schematic side view. On the far left, a part of a prismatic individual battery cell 2 is to be shown. This forms a first battery module denoted by 3 with many comparable individual battery cells 2. The individual battery cells 2 are stacked for this purpose in a stacking direction, which projects here into the sheet plane, and are located within a module housing 4, of which only one side wall can be seen here. Purely by way of example, two such battery modules 3 are shown here, which are positioned adjacent to one another, so that a small gap denoted by 5 remains between the two module housings 4.The module housings 4 are designed to be less high in a height direction h than the individual battery cells 2, so that a free space remains above the module housings 4 or their side walls.Above this free space there is a cell connector designated 6, which connects two battery poles, each designated 7, of individual battery cells 2 of the respective battery modules 3 to one another. In order to prevent a short circuit between the cell connector 6 and the module housings 4 which are connected to ground, a lacquer layer denoted by 8 is provided for electrically insulating the cell connector 6. This construction works very well, provided that a thermal event does not occur within one of the battery modules 3. If this is the case, hot gas will flow from the individual battery cells 2 through the free space between the two module housings 5 and the cell connector 6, which gas carries with it, for example, incandescent particles, liquid aluminum droplets or other hot and abrasive substances. This can lead to the paint layer 8 being decomposed or at least damaged in the event of such a so-called thermal event within the high-voltage battery 1. In this case, an undesired short circuit can occur between the cell connector 6 and the module housings 4, wherein these potential short-circuit paths are indicated here by two serrated arrows 9. Such short circuits are highly undesirable because, due to the high energy content of the battery modules 3, they ensure a further energy input into the high-voltage battery 1, which is already affected by a thermal event in any case. They are therefore highly safety-critical.In order to now efficiently prevent such short circuits, it is provided in the improved construction shown in FIG. 2 that a plastic element 10, here for example a plastic rod made of a solid or foamed plastic material, is inserted into the cavity between the two module housings 4 and the cell connector 6. This plastic element 10 is dimensioned such that it lies loosely in this region during regular operation, i.e. for example at a distance of a few tenths of a millimeter from the individual battery cells 2.The plastic material is selected such that it melts in the event of a thermal event in the high-voltage battery 1 and thus both closes the gap 5 and correspondingly covers the upper edges of the module housings 4 and reliably closes any intermediate spaces between the individual battery cells 2 and the module housing 4. The short-circuit paths marked 9 in FIG. 1 are therefore no longer possible even in the event that the paint 8 decomposes or is damaged. The risk of additional short circuits is thus prevented in an extraordinarily simple and efficient manner by the plastic element 10, so that the safety of such a high-voltage battery 1 is increased in the event of a thermal event.In the illustration of FIG. 3, a plan view of the structure according to FIG. 2 can be seen. One of the battery modules 3 is shown at the top and the other of the battery modules 3 at the bottom. The parts 4 of the module housings illustrated here and the plastic element 10, which is arranged below the two cell connectors 6 indicated by way of example, are situated between the battery modules. It projects beyond the stack of the individual battery cells 2 forming the respective module in the stacking direction, of which only some are shown here and also only some are provided with a reference sign.The structure of the battery modules 3 of the high-voltage battery 1, which are arranged here purely by way of example, adjacently, can then be arranged in a battery housing (not shown).

Claims

High-voltage battery (1) having at least two adjacent battery modules (3) which are electrically contacted with one another, wherein the battery modules (3) each have a module housing (4) which is grounded and which is formed to be less high than individual battery cells (2) of the battery modules (3), and wherein the electrical contact (6) between the battery modules (3) is arranged above the module housings (4), characterized in that a plastics element (10) is arranged between the upper edges of the adjacent module housings (4) and the electrical contact (6) between the battery modules (3).High-voltage battery (1) according to Claim 1, characterized in that the electrical contact (6) is electrically insulated by means of a paint (8).High-voltage battery (1) according to Claim 1 or 2, characterized in that the material of the plastics element (10) is selected such that, in the event of a thermal event, it melts in at least one of the battery modules (3).High-voltage battery (1) according to one of Claims 1 to 3, characterized in that the plastic element (10) is designed as a rod or strip.High-voltage battery (1) according to one of the preceding claims, characterized in that the plastic element (10) is solid or foamed.High-voltage battery (1) according to one of the preceding claims, characterized in that the plastic element (10) is loosely inserted between the battery modules (3).High-voltage battery (1) according to one of the preceding claims, characterized in that each of the battery modules (3) has a stack of prismatic individual battery cells (2).High-voltage battery (1) according to Claim 7, characterized in that the plastic element (10) runs in the stacking direction.High-voltage battery (1) according to one of the preceding claims, characterized in that the plastic element (10) is formed to be longer than the module housings (4).High-voltage battery (1) according to one of the preceding claims, characterized in that at least one of the module housings (4) is of trough-shaped design.

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