Method for applying potting compound

Abstract

The invention relates to a method for applying potting compound (4) to at least one cell module (1) of an electrical energy storage device comprising a predetermined number of electrically interconnected individual cells (2). According to the invention, the potting compound (4) is applied to a top surface of the cell module (1) by means of a single-cavity or fourteen-cavity mixing head of a potting system in at least one predetermined travel path (V1, V1', V2, V2', V3, V4).

Description

[0001] The invention relates to a method for applying potting compound to at least one cell module of an electrical energy storage device comprising a predetermined number of electrically interconnected individual cells.

[0002] From WO 2023 / 072523 A2, a battery fire prevention system and a method for preventing a battery fire resulting from thermal runaway of a battery cell are known, wherein a battery of a motor vehicle comprises several battery cells.The battery fire prevention system comprises a cell degassing channel connectable to the battery cells, into which gas escaping from each of the battery cells can be introduced and discharged to an outlet opening of the cell degassing channel, a gas flow control structure as part of the cell degassing channel designed to influence the course of the gas flow through the cell degassing channel formed by the gas escaping from the first battery cell, and a cooling device for cooling the thermally runaway first battery cell, wherein the cooling device is configured such that it is supplied with a coolant at the latest when the first battery cell thermally runsaway.

[0003] Furthermore, DE 10 2015 102 688 A1 describes a method for providing a battery cell structure. The method comprises providing a battery cell; providing a first tab and a second tab extending from the battery cell; and providing a potting compound on the battery cell.

[0004] EP2797136A1 describes a thin-film battery module. The thin-film battery module consists of: a battery module configured with stacked individual cells; and a shock-absorbing part that surrounds the space between the device cells and the battery module. Also described are a thin-film battery pack, a thin-film battery pack manufacturing device, and a thin-film battery pack manufacturing process.

[0005] DE102009011656A1 describes how, in order to bond non-exactly cylindrical cells in several layers over the intervening half-shell receptacles without direct contact of the cells to the half-shell receptacles, a curable potting compound with a defined layer is applied to the cells, and when this potting compound has reached a defined viscosity, the cells are positioned and fixed between the half-shell receptacles, and the potting compound is cured.

[0006] DE102018010115A1 relates to a method for manufacturing a battery comprising several battery cells for a motor vehicle, in which a thermal paste is applied to the battery cells, by means of which the battery cells are at least thermally coupled to a cooler for cooling the battery cells, wherein when applying the thermal paste the respective height of the respective battery cell is detected, wherein the thermal paste is applied to the respective battery cell depending on the respective detected height.

[0007] DE102022120287A1 relates to a cell carrier for a battery module, a battery module, and a method for assembling a battery module. The battery module includes a plurality of pairs of battery cells and the cell carrier. The cell carrier includes a plurality of recesses, each of which includes a first recess section comprising a first side wall section and a first bottom section, and a second recess section comprising a second side wall section and a second bottom section. The first bottom section and the second bottom section of each recess include a common cutout. For each pair of battery cells, a first end of a first battery cell is connected to the first recess section, and a first end of a second battery cell is connected to the second recess section of the respective recess.

[0008] DE 20 201 5 009 827 U1 relates to a device for manufacturing a component using a curable polyurethane potting compound, comprising a cavity for receiving the potting compound and an injection device movable along the cavity, which injections the potting compound into the cavity during an injection period, wherein the potting compound cures after injection with the cavity closed as a result of a chemical reaction, wherein the injection device is associated with a mixing device which changes the chemical composition of the potting compound during the injection period, wherein the mixing device adds an agent to the potting compound at least at the beginning of the injection period which slows down or delays the chemical reaction in relation to the potting compound injected towards the end of the injection period, and wherein the potting compound has two different polyol components which are supplied to a mixing chamber via separate supply lines.which is located directly upstream of the injection device or is part of the injection device.

[0009] The invention is based on the objective of specifying a method for applying potting compound to at least one cell module of an electrical energy storage device.

[0010] The problem is solved according to the invention by a method which has the features specified in claim 1.

[0011] Advantageous embodiments of the invention are the subject of the dependent claims.

[0012] According to the invention, a method for applying potting compound to at least one cell module of an electrical energy storage device, comprising a predetermined number of electrically interconnected individual cells, provides that the potting compound is applied to a top surface of the cell module by means of a single- or fourteen-cavity mixing head of a potting system in at least one predetermined travel path. During a travel path of the single- or fourteen-cavity mixing head for potting the spaces between individual cells, the potting compound is dispensed in such a way as to create a predetermined layer thickness. The potting compound dispensed by means of the single- or fourteen-cavity mixing head is first introduced into the spaces at least between the individual cells, and the predetermined layer thickness S1 is created.

[0013] By applying the method, it is possible to apply the potting compound in a defined and comprehensive manner to the top surface of the cell module, i.e., to fill the spaces between individual cells running in the direction of a longitudinal axis and the top surfaces of the individual cells with a required layer thickness of potting compound.

[0014] The potting compound is used to prevent or limit the spread of thermal runaway from a single cell to neighboring cells. By applying this potting compound, it can therefore be largely achieved that thermal runaway is confined to the individual cell.

[0015] The potting system's process program is optimized to apply a predetermined layer thickness to the cell surface and fill the spaces between the individual cells. This type of coating of the cell module's top surface, partially filling the spaces, can be described as top potting.

[0016] In one embodiment of the method, during a movement of the single- or fourteen-cell mixing head, the volume of potting compound dispensed is adjusted depending on the position of the single- or fourteen-cell mixing head relative to the top surface of the cell module. Specifically, the volume, i.e., the dispensed quantity, is adjusted depending on whether the single- or fourteen-cell mixing head moves over the spaces between the individual cells or over the top surfaces of the individual cells. For example, a larger quantity of potting compound is dispensed over the spaces than when the single- or fourteen-cell mixing head moves over the top surface of the individual cells.

[0017] According to the invention, during a movement of the 1-cell or 14-cell mixing head for potting the spaces between individual cells, the potting compound is dispensed in such a way that a predetermined layer thickness of, for example, approximately 5.5 mm is produced. In particular, the individual cells are arranged in a cell holder and / or displacement body, by means of which the individual cells are positioned and aligned relative to each other, and whose surface also forms an application area for the potting compound, so that the potting compound is filled into the spaces, in particular between the individual cells, to a certain depth.

[0018] In one embodiment, during the travel path of the single- or fourteen-cell mixing head for potting the top surface of individual cells, the potting compound is dispensed in such a way that a predetermined additional layer thickness of, for example, approximately 1 mm is created on the cell surface. Specifically, the potting compound is applied to the cell surface with a predetermined layer thickness, covering a cell rupture disc of the respective individual cell. The layer thickness is predetermined, particularly to prevent, as far as possible, the thermal runaway of an individual cell from spreading to adjacent individual cells.

[0019] According to the invention, the potting compound dispensed by means of the single- or fourteen-cell mixing head is first introduced at least into the spaces between the individual cells, thus creating the predetermined layer thickness of, for example, approximately 5.5 mm. The potting compound is first introduced into the spaces between the individual cells because it flows optimally in these spaces to achieve the desired layer thickness of, for example, approximately 5.5 mm.

[0020] In another possible configuration, a meandering traverse motion is performed using the single- or fourteen-cell mixing head to introduce the potting compound into the spaces between the individual cells. This means that the spaces between the individual cells are filled in a single traverse motion, particularly with the single-cell mixing head, and the layer thickness is set to 5.5 mm.

[0021] In one embodiment, the potting compound is applied to the top of the cell module at a temperature in a range of 40°C to 60°C, in particular at a temperature of about 50°C, so that the potting compound has sufficient flowability to distribute itself optimally on the top of the cell module, especially in the spaces between, so that the layer thickness is achieved and the top of the cell module is completely covered with the potting compound as a top coating.

[0022] In a further development of the process, the travel path of the single or fourteen-fold mixing head runs in the direction of a longitudinal axis of the cell module, so that a number of the travel paths of the single or fourteen-fold mixing head are optimized to produce the top potting of the cell module.

[0023] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0024] This shows: Fig. 1. Schematic perspective view of a cell module comprising several individual cells of an electrical energy storage device, Fig. 2 schematically a perspective view of the cell module with potting compound applied to one top surface, Fig. 3 schematically a cross-sectional view of the cell module with applied potting compound, Fig. 4 schematically an enlarged section of a cross-sectional view of the cell module Fig. 5 schematically a top view of the cell module with a travel path of a single mixing head of a potting system, Fig. 6 schematically a top view of the cell module with a travel path of a 14-fold mixing head of a potting system and Fig. 7 schematically a top view of the cell module with alternative travel paths of a single mixing head of a potting system.

[0025] Corresponding parts are marked with the same reference symbols in all figures.

[0026] Fig. Figure 1 shows a perspective view of a cell module 1 for an electrical energy storage device, particularly for a vehicle. The electrical energy storage device is, for example, a traction battery of an electric vehicle, a hybrid vehicle, or a fuel cell-powered vehicle.

[0027] Cell module 1 has a predetermined number of electrically connected series and / or parallel components in the Fig. 3 to 7 individual cells 2 shown in more detail, which according to the present embodiments are in the Fig. 1 to 7 are designed as round cells, i.e., they have a cylindrical cell housing 2.1. The individual cells 2 of the cell module 1 are arranged in a common housing 6, which is box-shaped.

[0028] The individual cells 2 have a so-called cell rupture disc 3 in the area of ​​a cell surface, for example when inserted into a cell lid, as shown in an exemplary and highly simplified example in Fig. Figure 3 shows that this cell rupture disc 3 is designed to rupture, i.e., break open, when an individual cell 2 has an internal pressure that exceeds a predetermined threshold, in order to selectively reduce the internal pressure of the individual cell 2. Such a case is referred to as thermal runaway of the individual cell 2. The gases escaping from the cell housing 2.1 have a comparatively high temperature, so that the gases pose a fire risk to the cell module 1 and thus also to the electrical energy storage system.

[0029] To largely prevent adjacent individual cells 2 of the defective individual cell 2 from also experiencing thermal runaway, it is planned that one upper surface of the cell module 1 will be coated with a potting compound 4, which is, for example, a thermally conductive epoxy resin and / or polyurethane. This is shown in Figure 1. Fig. 2 a perspective view of cell module 1 with applied potting compound 4.

[0030] Fig. Figure 3 shows a sectional view of one of the cell modules 1 with potting compound 4 and cell holder 5, wherein in Fig. Figure 4 shows a sectional view of an enlarged section of the cell module 1 with potting compound 4 and cell holder 5.

[0031] The individual cells 2 of the cell module 1 are aligned and positioned by means of a cell holder 5, or alternatively or additionally by means of a displacement body, so that, for example, a predetermined distance between adjacent individual cells 2 can be set. The cell holder 5, which extends essentially over the entire surface of the cell module 1, is arranged in the region of an upper half of the cell housing 2.1 of the individual cells 2, with a defined distance set between a surface of the cell holder 5 and the upper surface of the individual cells 2. The cell holder 5 is thus positioned in a predetermined position relative to the individual cells 2.

[0032] For example, the cell holder 5 is plate-shaped and has a number of recesses corresponding to the number of individual cells 2, the shape of which corresponds to a shape of the cell housing 2.1 of the individual cells 2. In particular, each individual cell 2 is inserted into a recess A, thereby creating a positive fit between the cell housing 2.1 and the recess A, i.e., the cell holder 5.

[0033] To ensure that the potting compound 4 is applied in a defined manner to the top of the cell module 1, the cell module 1 is fed to a potting system (not shown in detail), whereby the potting compound 4 is applied to the top of the cell module 1 by means of a single-stage mixing head or a fourteen-stage mixing head.

[0034] An upper surface of the cell holder 5 forms a contact surface for the potting compound 4, which is introduced in particular into spaces Z, especially in the direction of a longitudinal axis of the cell module 1, between rows of adjacent individual cells 2.

[0035] In particular, the cell holder 5 is arranged with respect to the individual cells 2 of the cell module 1 such that a predetermined layer thickness S1 of the potting compound 4 in the area of ​​the gaps Z is approximately 5.5 mm. A further predetermined layer thickness S2 of the potting compound 4 applied to the cell tops is approximately 1 mm, whereby the potting compound 4 forms a complete surface coating on the top of the cell module 1, as shown in Fig. 2 is shown, which is generated.

[0036] Fig. Figure 5 shows a top view of cell module 1 with travel paths V1, V2 of a single mixing head and in Fig. Figure 6 shows a top view of cell module 1 with travel paths V3 and V4 of a 14-cavity mixing head. Travel paths V1 to V4 each form a so-called potting line.

[0037] According to the in Fig. In the embodiment shown in section 5, the travel paths V1, V2 run according to a Fig. 7. Travel direction R shown. A first travel path V1 is provided in particular for closing the gaps Z, on the one hand between a housing wall 6.1 of the housing 6 of the cell module 1 and on the other hand between individual cells 2, which are arranged essentially in a row along the longitudinal axis of the cell module 1.

[0038] Along the first travel path V1, in particular along the gaps Z between the housing wall 6.1 and the individual cells 2, the potting compound 4 is dispensed in a volume of approximately 12 ml or approximately 14 ml, depending on the length of the cell module 1, and applied to the gap Z. The larger volume of potting compound 4 dispensed corresponds to the longer cell module 1.

[0039] Along the first travel path V1 for applying the potting compound 4 into spaces Z between the individual cells 2 along the travel direction R, in particular in the direction of the longitudinal axis of the cell module 1, the potting compound 4 is dispensed with a volume of approximately 10.23 ml or with a volume of approximately 12.5 ml, depending on the length of the cell module 1, and applied into the space Z.

[0040] A second travel path V2 of the single mixing head of the potting system runs directly over the cell tops of the individual cells 2, for example directly over the respective cell bursting disc 3.

[0041] On a second travel path V2, which is located closest to the first travel path V1 facing the housing wall, the potting compound 4 is dispensed with a volume of approximately 6.55 ml or 8 ml, depending on the length of the cell module 1, and applied to the cell tops.

[0042] On the remaining second travel paths V2 of the single mixing head, the potting compound 4 is dispensed with a volume of approximately 8.2 ml or approximately 6.71 ml, respectively, to completely seal the top surface of the cell module 1 with the potting compound 4.

[0043] The potting compound 4 is applied to the top surface of the cell module 1 at a temperature of approximately 50°C. First, the gaps Z are filled with the potting compound 4, which allows it to flow more easily into these gaps. The dispensing rate at which the potting compound 4 is applied is the same on all travel paths V1 and V2 of the single-stage mixing head.

[0044] Fig. Figure 6 shows the travel paths V3, V4 of the 14-fold mixing head of the potting system, with which the potting compound 4 is applied to the top surface of the cell module 1, in particular over the entire surface.

[0045] The potting compound 4 is dispensed along a third travel path V3 to apply the potting compound 4 into the spaces Z between housing wall 6.1 and a series of individual cells 2 arranged along this wall, depending on the length of the cell module 1 with a volume of approximately 11.8 ml or a volume of approximately 15 ml.

[0046] Along the third travel paths V3 between the third travel paths V3 facing the housing walls 6.1, the potting compound 4 is introduced into the spaces Z between the rows of individual cells 2 with a volume of approximately 10.6 mm or with a volume of approximately 13.4 ml, depending on the length of the cell module 1.

[0047] Along fourth travel paths V4, the potting compound 4 is dispensed with a volume of approximately 4.5 ml or 5.8 ml, depending on the length of the cell module 1, and applied to the cell tops of the individual cells 2, with the further layer thickness S2 of the potting compound 4 being approximately 1 mm.

[0048] Thus, a closed lid is created on the top of the cell module 1, whereby the application of the potting compound 4 across the entire surface largely prevents the spread of thermal runaway.

[0049] In Fig.Figure 7 is a top view of cell module 1 with alternative travel paths V1', V2' of a Single mixing head of the potting system shown.

[0050] The single mixing head is designed to follow a meandering path V1', so that the potting compound 4 is dispensed in a single movement to fill the spaces Z between housing walls 6.1 and individual cells 2, as well as between rows of individual cells 2. For example, it is also possible to vary the volume of potting compound 4 dispensed by the single mixing head according to the position of the single mixing head relative to the top of the cell module 1.

[0051] Each second travel path V2', which runs between two first travel paths V1' over the cell tops of the individual cells 2, is traversed by means of the single mixing head in such a way that one side of the cell module 1, in particular another housing wall 6.2 of the housing 6, at which a second travel path V2' ends, represents a beginning of another second travel path V2', which ends on an opposite side of the cell block 1 and thus on an opposite housing wall 6.2. Reference symbol list 1 cell module 2 single cells 2.1 Cell casing 3 cell rupture disc 4. Potting compound 5 cell holders 6 cases 6.1 Housing wall 6.2 Further housing wall R direction of travel S1 layer thickness S2 further layer thickness V1, V1' first travel path V2, V2' second travel path V3 third travel path V4 fourth travel path Z space

Claims

[1] Method for applying potting compound (4) with respect to at least one cell module (1) of an electrical energy storage device comprising a predetermined number of electrically interconnected individual cells (2), wherein the potting compound (4) is mixed by means of a 1-cavity or 14-cavity mixing head of a potting system in at least one predetermined The travel path (V1, V1', V2, V2', V3, V4) is applied to a top surface of the cell module (1), wherein, during a travel path (V1, V1', V3) of the 1-fold or 14-fold mixing head for potting gaps (Z) between individual cells (2), the potting compound (4) is dispensed in such a way that a predetermined layer thickness (S1) is produced, characterized by , that the potting compound (4) dispensed by means of the 1-fold or 14-fold mixing head is first introduced into the spaces (Z) at least between the individual cells (2) and the specified layer thickness (S1) is produced. [2] Method according to claim 1, characterized by , that during a movement of the 1- or 14-fold mixing head, a volume of dispensed potting compound (4) is set depending on the position of the 1- or 14-fold mixing head in relation to the top of the cell module (1). [3] Method according to claim 1 or 2, characterized by , that during a travel path of the 1-fold or 14-fold mixing head for potting a cell top of the individual cells (2) the potting compound (4) is dispensed in such a way that a predetermined further layer thickness (S2) is created on the cell top. [4] Method according to any one of claims 1 to 3, characterized by , that a meandering traversing movement is carried out by means of the 1-fold or 14-fold mixing head to introduce the potting compound (4) into the spaces (Z) between the individual cells (2). [5] Method according to any of the preceding claims, characterized by, that the potting compound (4) is applied to the top of the cell module (1) at a temperature in a temperature range of 40°C to 60°C. [6] Method according to one of the specified claims, characterized by , that the travel path (V1, V1', V2, V2', V3, V4) of the 1-fold or 14-fold mixing head runs in the direction of a longitudinal axis of the cell module (1).

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