Battery unit, method for manufacturing a battery unit and battery

Abstract

The invention relates to a battery unit, a method for manufacturing a battery unit, and a battery. The battery unit (1) according to the invention comprises a plurality of cells (2), wherein the cells (2) are arranged in cell stacks (3) under mechanical preload, and a side wall (4) is attached to the cells on opposite sides of a cell stack to keep the cells of a cell stack under preload.

Description

[0001] The invention relates to a battery unit, a method for manufacturing a battery unit and a battery.

[0002] US 11 757 144 B2 discloses a plurality of battery cells arranged as a stack, with a thermally insulating material positioned between two battery cells. The stack is held together by means of two clamps.

[0003] A battery unit according to the invention comprises a plurality of cells, wherein the cells are arranged in cell stacks under mechanical preload, and a side wall is attached to the cells on opposite sides of a cell stack in order to keep the cells of a cell stack under preload.

[0004] The preload improves mechanical stability, ensures uniform pressure on the cells to maintain cell properties, and enhances heat dissipation in the battery unit and in batteries comprising one or more such battery units according to the invention. The side walls allow the cells to be held under sufficient and defined preload. This eliminates the need to apply preload using other battery components, particularly a housing.

[0005] The invention makes it possible to separate the functions of the battery's structural elements. It is particularly advantageous that the battery unit itself is not designed to absorb external forces acting on the battery, but that this function is performed by other structural elements of the battery, especially the housing. This separation saves space and allows for better use of the available space, thus enabling a higher energy density of the battery.

[0006] A preferred preload for a cell stack is in the range of 0 to 1 MPa.

[0007] In another embodiment, the side wall is attached to the cell stack with an adhesive. This allows for a secure and cost-effective fastening.

[0008] In another embodiment, a thermally insulating material is arranged within a cell stack between at least two adjacent cells. This reduces the risk of uncontrolled heat spread between battery cells ("thermal runaway").

[0009] In another embodiment, several cell stacks are arranged side by side lengthwise. This allows for a compact arrangement of the individual cell stacks to achieve a high energy density.

[0010] In another embodiment, the battery unit comprises a base plate, with a cell stack being attached to the base plate using an adhesive. This allows several cell stacks to be combined into a single assembly unit. This enables simple and reliable integration, preferably into a battery housing.

[0011] In another embodiment, the battery comprises a frame and at least one battery unit, wherein the battery unit is received by the frame. This allows for a mechanically stable battery construction and protection of the cells from external influences. The frame is preferably part of a battery housing.

[0012] In another embodiment, the battery comprises one or more longitudinal or transverse beams which, together with the frame, form one or more compartments into which a battery unit is inserted. This ensures that, in the event of an external force being applied to the battery, the force is not directly transmitted from the frame to the cells, but is instead absorbed by the transverse beams. This increases safety.

[0013] A method according to the invention for manufacturing a battery unit comprises the steps of: stacking several (prismatic) cells into a cell stack, applying a force to the cell stack with a preloading tool to generate a preload on the cells, attaching side walls to the longitudinal sides of a cell stack to maintain the preload, and removing the preloading tool. This allows for the rapid and cost-effective production of a battery with high energy density.

[0014] The battery unit and battery are particularly applicable in the automotive sector.

[0015] Preferred embodiments are explained in more detail with reference to the following figures. These show Fig. 1 an embodiment of a battery unit according to the invention, Fig. 2 an embodiment of a battery according to the invention with such a battery unit, and Fig. 3 a schematic representation of an embodiment of a method according to the invention for manufacturing the battery unit.

[0016] The battery unit 1 comprises a plurality of (prismatic) cells 2. These cells 2 are arranged in cell stacks 3 under mechanical preload, here with a voltage in the range of 0 MPa ≤ P ≤ 1 MPa. A side wall 4 is attached to the longitudinal sides of each cell 2 on opposite sides of a cell stack 3. These side walls 4 hold the cells 2 of a cell stack 3 under a defined preload. Within a cell stack 3, a thermally insulating material 6 is arranged between each pair of adjacent cells 2 to reduce unwanted heat transfer between the cells 2. Several cell stacks 3 are arranged side by side along their length.

[0017] In this embodiment, the side walls 4 are implemented as rigid plates (e.g., made of sheet metal). The side wall 4 is attached to the cell stack 3 with an adhesive 5, in this case, double-sided adhesive tape. Alternatively, the connection can be made with liquid adhesive, preferably a structural adhesive. The adhesive used has thermally insulating properties, thus reducing heat transfer between the cells 2.

[0018] The battery unit 1 comprises a base plate 8. The cell stacks 3 are attached to the base plate 8 with an adhesive 9. The base plate 8 is rigid and, in this embodiment, is made of sheet metal. The adhesive 9, here a liquid structural adhesive, is applied over the entire surface of the base plate 8. The base plate 8 includes several fastening elements, here lateral tabs for screw connections, for mounting the battery unit in a battery housing.

[0019] An embodiment of a battery according to the invention with several battery units 1 shows Fig. 2. The battery comprises a frame 20. The frame 20 is rectangular and multi-part. It consists of extruded profiles and, together with a lid (not shown) and a base, forms a battery housing. The base has a cooling structure that allows the battery units to be cooled. Thermal connection is ensured by bonding the base to the base plate 8 with a thermally conductive adhesive.

[0020] The battery comprises several crossbeams 21. The crossbeams are connected at their ends to the frame 20. The crossbeams 21, together with the frame 20, form several compartments. A battery unit 1 is inserted into each compartment.

[0021] The crossbeams 21 are designed as rigid structural elements for mounting the battery units and absorbing forces from external influences on the battery. Here, the crossbeams 21 consist of extruded profiles. In one variant, the crossbeams 21 are made of sheet metal.

[0022] The battery unit 1 is screwed to the crossbeams 21 via the base plate 8 of the battery unit 1. The cells 2 therefore have no direct connection to the frame 20, so that forces acting on the frame 20 are essentially absorbed by the frame 20 and the crossbeams 21.

[0023] The process for manufacturing a battery unit 1 comprises several steps. In a first step 50, several (prismatic) cells 2 are stacked to form a cell stack 3. Then, in a second step 51, a force is applied to the cell stack 3 using a preloading tool to generate the desired preload of the cells 2. Subsequently, in a third step 52, side walls 4 are attached to the longitudinal sides of a cell stack 3 to maintain the preload after the preloading tool is removed. The side walls 4 are attached to the longitudinal sides of a cell stack 3 using an adhesive 5. After the adhesive has cured, the preloading tool is removed in a fourth step 53.

[0024] According to a first embodiment, the side walls 4 are first attached to the cells 2. Subsequently, the cell stacks 3 thus formed are placed on the base plate 8.

[0025] According to a second embodiment, side walls 4 are first placed on the base plate 8 and attached to it. Here, the attachment is achieved by welding. Subsequently, the stacked cells 2 are inserted under prestress and fixed to the side walls 4 with adhesive, in this case liquid structural adhesive.

[0026] The process is repeated until the target number of units for the battery to be equipped is reached.

[0027] The battery is suitable for use in the automotive sector, for example in electrically powered vehicles. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 11 757 144 B2

[0002]

Claims

[1] Battery unit (1) comprising a plurality of cells (2) wherein the cells are arranged in cell stacks (3) under mechanical preload and a side wall (4) is attached to the cells on opposite sides of a cell stack to keep the cells of a cell stack under preload. [2] Battery unit according to claim 1, wherein the side wall (4) is attached to the cell stack (3) with an adhesive (5). [3] Battery unit according to one of the preceding claims, wherein a thermally insulating material (6) is arranged within a cell stack (3) between at least two adjacent cells (2). [4] Battery unit according to one of the preceding claims, wherein several cell stacks (3) are arranged side by side longitudinally. [5] Battery unit according to one of the preceding claims, comprising a base plate (8), wherein a cell stack (3) is attached to the base plate (8) with an adhesive (9). [6] Battery comprising a frame (20) and at least one battery unit (1), wherein the battery unit (1) is received by the frame (20). [7] Battery according to claim 6 comprising one or more longitudinal and / or transverse beams (21) which together with the frame (20) form one or more compartments into which a battery unit (1) is inserted. [8] Method for manufacturing a battery unit (1) comprising the steps: - Stacking (51) several prismatic cells (2) to form a cell stack (3) - Applying (52) a force to the cell stack (3) using a prestressing tool to generate a prestress on the cells (2) - Attaching (53) side walls (4) to the longitudinal sides of a cell stack (3) to maintain the prestress - Removal (54) of the preloading tool [9] The method of claim 8, comprising the step of: - wherein the side walls (4) are attached to the long sides of a cell stack (3) with an adhesive (5). [10] Method according to claim 8 or 9, wherein the steps are repeated until the number of units for the battery is reached.

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