Method for assembling a battery module

Abstract

The invention relates to a cell holder (1) comprising a separating wall (2) and two sliding guide elements (3) which are provided on opposite edges of the separating wall (2) and are configured so that when arranged in a packaging space (4) of a module frame (5) each is supported via sliding guide surfaces (6) that positively fit sliding guide rails (7) on the module frame (5), wherein at least two cell holders (1) can be stacked orthogonally in relation to a plane of extension (E) of the separating wall (2) to form a cell receptacle for a galvanic cell (8), wherein in their stacked condition cell holders (1) can be moved relative to the module frame (5) and relative to one another in the stacking direction (SR). The cell holder according to the invention is characterized by at least one through-hole (9) which extends through each sliding guide element (3) in the stacking direction (SR), the cross-sectional shape of the through-hole (9) being adapted to the cross-sectional shape of an assembly rod (10) so that the assembly rod (10) can pass through the through-hole (9) in the stacking direction (SR).

Description

[0001] Mercedes-Benz Group AG

[0002] Method for assembling a battery module

[0003] The invention relates to a method for assembling a battery module comprising a cell holder.

[0004] Battery cells can change their volume over their lifespan. This is particularly true for battery cells with lithium anodes. During a charge or discharge cycle, the battery cells can expand and contract. This phenomenon is also known as "breathing" or "cell breathing." In addition, volume changes occur due to aging.

[0005] Typically, several battery cells are electrically connected to each other to achieve a desired cell voltage or capacity. The battery cells are arranged within a housing. Several battery cells can be connected together to form modules. Each battery module or battery must be designed so that changes in the volume of the individual battery cells do not adversely affect their operation. In particular, sufficient space should be provided to accommodate these volume changes. If the battery cells are restricted in their expansion, they will be compressed against each other and subjected to pressure. This can cause the materials from which the battery cells are made to wear down and accelerate the aging of the battery cells.

[0006] German patent application DE 102020 003 892 B4 discloses a cell holder for at least one battery cell and a cell module. The document describes a carrier for battery cells. The carrier consists of essentially rectangular walls that can be stacked in a stacking direction. Cavities are formed between the individual walls, which serve to hold the battery cells. The arrangement of battery cells and carrier is inserted into a module frame of a corresponding battery module. The respective carriers are supported on the module frame by corresponding guide structures. The carriers are not fixed relative to the module frame in the stacking direction, so that the carriers can move together with the battery cells in the stacking direction. This allows the aforementioned volume changes of the battery cells to be accommodated. The battery cells are preferably so-called pouch cells.

[0007] During operation, it is essential to monitor the battery cells to verify that the battery is functioning within its intended parameters. The mobility of the battery cells relative to one another complicates this monitoring. Furthermore, the demands placed on the electrical interconnection of relevant electronic components increase. Assembling a battery module is also challenging. Therefore, maintaining the safety of the individual battery components, particularly preventing short circuits, is a critical task under these demanding conditions.

[0008] Furthermore, DE 102013 021 549 A1 discloses a high-voltage battery. The high-voltage battery comprises a plurality of individual battery cells that are clamped together in a cell block via a tension rod. For this purpose, the individual battery cells are arranged on cell holders, the perimeter of which has openings for the insertion of the tension rod.

[0009] Furthermore, CN 2 19 937259 U discloses a battery module. The battery module comprises a housing in which stacked cell holders are arranged. A pouch cell is arranged in the space between each pair of adjacent cell holders. Here, too, the cell holders have through-holes at their perimeter through which a rod is inserted.

[0010] The present invention is based on the objective of providing an improved method for assembling a battery module, which can be carried out quickly, reliably, and with minimal effort.

[0011] According to the invention, this problem is solved by a method for assembling a battery module with the features of claim 1. Advantageous embodiments and further developments are described in the dependent claims.A cell holder of this type, comprising a partition and two sliding guide elements provided on opposite edges of the partition, which are configured to be positively supported on sliding guide rails of the module frame via sliding guide surfaces when arranged in a packaging space of a module frame, wherein at least two cell holders are stackable orthogonally to a plane of extension of the partition to form a cell receptacle for a galvanic cell, wherein each cell holder is movable relative to the module frame and to each other in the stacking direction when stacked, comprises at least one through-opening extending in the stacking direction through each sliding guide element, the cross-sectional shape of which is adapted to the cross-sectional shape of a mounting rod in order to allow the mounting rod to pass through the through-opening in the stacking direction.

[0012] Several cell holders can be inserted into the packaging space of the module frame. Between each cell holder, a cell receptacle is formed for each individual electrolytic cell. The electrolytic cells can be electrically connected, for example, in parallel and / or series. This allows the desired voltage and capacity to be set for a corresponding battery module. The volume of the electrolytic cells changes between charging cycles and over their service life. Since the cell holders with their respective electrolytic cells are movable in the stacking direction, these volume changes can be accommodated without compressing the electrolytic cells against each other.

[0013] The electrical wiring of the galvanic cells and the installation of sensor elements for monitoring the operating conditions of the corresponding battery module, such as temperature sensors or devices for monitoring internal resistances, voltages, current, and the like, are typically carried out before the assembly is inserted into the packaging space. Consequently, accessibility to relevant areas on the cell holder or the galvanic cell is typically comparatively poor after insertion into the packaging space. However, these areas are easily accessible before insertion. During assembly, electrically conductive or signal-carrying components must be connected. Cables that are prone to tearing can be used for this purpose, complicating the assembly process.According to the invention, the individual cell holders, and thus the galvanic cells, are fixed in place, reducing the risk of cables tearing. For this purpose, at least one sliding guide element of each cell holder includes a through-opening through which a mounting rod can be inserted. Using this mounting rod, the arrangement of several cell holders and galvanic cells can be fixed relative to one another, except in the stacking direction, thus preventing undesirable relative movements during pre-assembly. This allows the battery module to be assembled quickly, safely, easily, and reliably. Furthermore, such an arrangement can be easily and safely inserted into the packaging space.The mounting rod can have an end stop, allowing, for example, the insertion of a clamping element at the opposite end of the mounting rod to secure it in the stacking direction after all cell holders have been threaded onto the rod. This clamping element must be removed before the assembly is placed in the packaging space.

[0014] The opening can have a circular cross-sectional shape. Generally, all possible cross-sectional shapes are suitable, such as round, oval, or even any polygonal shape. For example, it could be rectangular, square, star-shaped, or similar. However, with a polygonal cross-section, the mounting rod must be oriented precisely relative to the opening to be inserted. With a circular shape, on the other hand, the mounting rod can be inserted through the opening in any position, regardless of its rotation around its longitudinal axis.

[0015] The mounting rod can also be chamfered or have a conical tip at one or both of its ends. This facilitates threading the mounting rod into the through-hole. Alternatively, as already mentioned, the mounting rod can also be provided with a stop plate or have a thickening at one of its ends. This prevents cell holders threaded onto the mounting rod from slipping off. According to the invention, a method for mounting a battery module, comprising at least two cell holders as described above, at least one galvanic cell, and a module frame, is further developed by the following process steps:

[0016] - Passing at least one first mounting rod through the through-opening of at least one sliding guide element of a first cell holder;

[0017] - Arranging a galvanic cell on the first or a second cell holder;

[0018] - Slide the second cell holder onto at least the first mounting rod, so that the first and second cell holders form the cell receptacle for the galvanic cell;

[0019] - optional: appropriate arrangement of additional cell holders and galvanic cells;

[0020] - Inserting the assembly consisting of at least the first cell holder, second cell holder, galvanic cell, and at least the first mounting rod into the packaging space of the module frame; and

[0021] - Removal of all mounting rods from the module frame.

[0022] The mounting rod allows the assembly of cell holders and galvanic cells to be fixed in place, significantly simplifying its insertion into the packaging space. In particular, it prevents the tearing of electrical wiring, contacts, connections, and the like. After the assembly is inserted into the packaging space, the mounting rods can be easily pulled out of the corresponding through-holes in the opposite direction. Thanks to the support of the sliding guide elements via the sliding surfaces on the module frame's guide rails, the precise positioning of the assembly's components relative to each other is maintained.

[0023] Preferably, at least one mounting rod is threaded through each sliding guide element. This allows the arrangement of cell holders and electrolytic cells to be fixed not only on one side, but also on at least two sides of each cell holder. In a top view in the stacking direction, two through-openings can particularly preferably be provided in each of the corresponding sliding guide elements, so that mounting rods can be guided through a left upper and lower through-opening and a right upper and lower through-opening. The individual through-openings in the sliding guide elements are located at the same position from one sliding guide element to the next, so that when cell holders and electrolytic cells are stacked, the respective through-openings are aligned in the stacking direction. This allows the corresponding mounting rods to be guided through all cell holders or sliding guide elements in the stacking direction.

[0024] Preferably, at least one pre-assembly step is performed before the assembly is inserted into the packaging space. Fixing the cell holders and galvanic cells to each other not only facilitates the insertion of the assembly into the module frame's packaging space, but also allows, as already described, for the corresponding pre-assembly steps to be carried out due to the good accessibility of the relevant components.

[0025] The corresponding pre-assembly steps can be carried out once all the necessary cell holders and electrolytic cells for forming the assembly have been threaded onto the respective mounting rods. However, it is also possible to perform some or all of the pre-assembly steps gradually, i.e., to carry out one or more pre-assembly steps after each cell holder and / or electrolytic cell has been threaded onto the rods.

[0026] Preferably, at least one of the following pre-assembly steps is carried out:

[0027] - Transporting the arrangement;

[0028] - Welding of components, in particular welding of cell terminals of one or more galvanic cells;

[0029] - Soldering of components;

[0030] - Cabling of components; and / or

[0031] - Performing a functional test of components.

[0032] The relevant components can include current-carrying components such as contact plates, wires, conductor tracks, conductors, plugs and the like, as well as sensors, measuring probes, valves, bursting elements and the like.

[0033] Various pre-assembly steps are possible, allowing the assembly to be almost completely completed before being inserted into the packaging space. The assembly then simply needs to be inserted into the packaging space and connected to other modules via connection elements, such as connectors, which extend from the packaging space at designated points. These modules include, for example, additional battery modules or power electronics such as a battery management system.

[0034] Further advantageous embodiments of the cell holder according to the invention and of the method according to the invention for mounting the battery module also result from the exemplary embodiments which are described in more detail below with reference to the figures.

[0035] This shows:

[0036] Fig. 1 shows a schematic exploded view of a cell holder;

[0037] Fig. 2 shows a schematic representation of a battery module according to the invention;

[0038] Fig. 3 shows a schematic detail of a sliding guide element of the cell holder;

[0039] Fig. 4 shows a schematic detail of several cell holders fixed by means of a mounting rod; and

[0040] Fig. 5 shows a schematic detail of cell holders fixed by means of several mounting rods.

[0041] Figure 1 shows a cell holder 1 comprising a partition 2 and two sliding guide elements 3 arranged on opposite edges of the partition 2. The partition 2 extends in a plane E, with several cell holders

[0042] The cells are stackable in a stacking direction SR orthogonal to the plane of extension E. Two adjacent partition walls 2 each form a cell receptacle for the galvanic cells 8 shown in Figure 2. In the embodiment shown, the galvanic cells 8 are pouch cells.

[0043] As shown in Figure 2, the cell holders 1 and galvanic cells 8 stacked in this manner can be placed in the packaging space 4 of a module frame 5 to form a battery module.

[0044] Introduce II.

[0045] The sliding guide elements 3 have sliding guide surfaces 6 which are positively engaged with sliding guide rails 7 of the module frame 5. This allows the cell holders 1 to be laterally fixed within the module frame 5, while each cell holder 1 remains movable relative to each other and relative to the module frame 5 in the stacking direction SR. Thus, the cell holders 1 and galvanic cells 8 can move in the stacking direction SR as the volume of the galvanic cells 8 increases or decreases. The resulting volume changes of the galvanic cells 8 can therefore be compensated, thereby minimizing the mechanical stress on the galvanic cells 8. The galvanic cells 8 can be electrically connected via cell connectors.

[0046] Figure 3 shows two of the sliding guide elements 3 in an enlarged view. Various components are visible, such as connectors 12, wiring 13 for the connectors 12, mounting points 14, and a screw 15 for attaching the sliding guide element 3 to the partition 2. A through-opening 9 in the stacking direction SR is also shown, through which a mounting rod 10, as shown in Figures 4 and 5, can be inserted. Viewed in the stacking direction SR, the respective through-openings 9 of the sliding guide elements 3 are aligned, so that the individual cell holders 1 can be threaded onto the aforementioned mounting rods 10.

[0047] Figure 4 shows a representation in which a corresponding mounting rod 10 is passed through several cell holders 1. The path of the through-opening 9 is indicated by two dashed lines. The cross-sectional shape of the through-opening 9 and the mounting rod 10 is particularly preferred as being circular. The individual cell holders 1 are fixed by threading them onto the mounting rod 10 transversely to the stacking direction SR, but remain movable relative to each other in the direction of the stacking direction SR.

[0048] It is also conceivable that a stopper element is threaded onto the mounting rod 10 to prevent the cell holders 1 from slipping in the stacking direction SR. Such a stopper element, not shown in detail, could, for example, be designed like a clamp. Alternatively, the mounting rod 10 could be threaded, allowing a nut to be screwed onto it.

[0049] It has at least one sliding guide element 3 for each cell holder 1, with at least one through-opening 9. Particularly preferably, however, each sliding guide element 3 has two through-openings 9, so that the advantageous embodiment of the arrangement of cell holders 1 and galvanic cells 8 shown in Figure 5 can be produced. In a top view of the arrangement in the stacking direction SR, a mounting rod 10 is thus provided in each corner of the arrangement. This ensures that the respective cell holders 1 and galvanic cells 8 are fixed particularly reliably.

[0050] Particularly advantageous is the ability to perform further pre-assembly steps after arranging the cell holders 1 and galvanic cells 8 on the respective mounting rods 10. These steps include soldering, welding, or electrically contacting components such as cell terminals, connectors, and the like. The assembly is then inserted into the packaging space 4 of the module frame 5, and the mounting rods 10 are removed.

Claims

Mercedes-Benz Group AG Patent claims 1. Method for assembling a battery module (11), the battery module (11) comprising at least two cell holders (1), each cell holder (1) comprising a partition (2) and two sliding guide elements (3) provided on opposite edges of the partition (2), which are configured to be positively supported on sliding guide rails (7) of the module frame (5) via sliding guide surfaces (6) when arranged in a packaging space (4) of a module frame (5), wherein at least two cell holders (1) are stackable orthogonally to a plane of extension (E) of the partition (2) to form a cell receptacle for a galvanic cell (8), wherein each cell holder (1) is movable relative to the module frame (5) and to each other in the stacking direction (SR) when stacked, and comprising at least one through-opening (9) extending in the stacking direction (SR) through each sliding guide element (3),the cross-sectional shape of which is adapted to the cross-sectional shape of a mounting rod (10) in order to enable the mounting rod (10) to pass through the through-opening (9) in the stacking direction (SR), the battery module (11) further comprising at least one galvanic cell (8) and the module frame (5), characterized by the following process steps:, - Passing at least one first mounting rod (10) through the through-opening (9) of at least one sliding guide element (3) of a first cell holder (1); - Arranging a galvanic cell (8) on the first or a second cell holder - Slide the second cell holder (1) onto at least the first mounting rod (10) so that the first and second cell holders (1) form the cell receptacle for the galvanic cell (8); - Inserting the assembly consisting of at least the first cell holder (1), second cell holder (1), galvanic cell (8) and at least the first mounting rod (10) into the packaging space (4) of the module frame (5); and - Removal of all mounting rods (10) from the through-holes (9) of the cell holders (1).

2. Method according to claim 1, characterized in that the through-opening (9) of the respective cell holder (1) has a circular cross-sectional shape.

3. Method according to claim 1 or 2, characterized in that after sliding the second cell holder (1) onto at least the first mounting rod (10), further cell holders (1) and galvanic cells (8) are arranged accordingly.

4. Method according to one of claims 1 to 3, characterized in that at least one pre-assembly step is carried out before the arrangement is introduced into the packaging space (4).

5. The method according to claim 4, characterized by at least one of the following pre-assembly steps being carried out: - Transporting the arrangement; - Welding of components, in particular welding of cell terminals of one or more galvanic cells (8); - Soldering of components; - Cabling of components; and / or - Performing a functional test of components.

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