Battery cell, in particular for an energy storage device for an electrically powered motor vehicle, energy storage device, motor vehicle and method

Abstract

Battery cell, in particular for an energy storage device for an electrically powered motor vehicle; wherein the battery cell has a cylindrical battery housing that defines an axial direction and a radial direction perpendicular to the axial direction; the battery cell has a cell winding arranged in the radial direction within the battery housing and comprising several layers; the battery cell has a winding insert; the winding insert is arranged in the radial direction within the cell winding; the winding insert is configured to be displaced along the axial direction when there is a pressure difference between an internal cell pressure and an ambient pressure; and the winding insert is configured to displace at least one radially inner layer of the layers along the axial direction when the winding insert is displaced along the axial direction.

Description

[0001] The present disclosure relates to a battery cell, in particular for an energy storage device for an electrically powered motor vehicle. The disclosure also relates to an energy storage device for an electrically powered motor vehicle, an electrically powered motor vehicle, and a method for manufacturing a battery cell.

[0002] Such an energy storage device typically comprises a plurality of battery cells connected in parallel and / or series, thus forming a high-voltage storage device also known as a traction battery. The energy storage device is designed to discharge the battery cells and provide electrical energy to operate the vehicle and / or to supply electrical energy externally, for example via a charging station, and to be supplied with electrical energy via the charging station and / or through recuperation during driving in order to charge the battery cells of the energy storage device.

[0003] According to the publication "PRODUCTION PROCESS OF A LITHIUM-ION BATTERY CELL", Frankfurt am Main, January 2023, self-published by PEM of RWTH Aachen & VDMA, 4th edition, ISBN: 978-3-947920-26-6, it is known, within the context of cell assembly for electrode manufacturing, to wind electrodes and separators into a cell coil, also called a "jelly roll". The winding is done around a center pin. The center pin can either be removed or remain in the cell coil.

[0004] Furthermore, it is known to provide a pressure equalization device, a so-called vent, in such battery cells, in order to allow, in particular, the release of gas from the battery cell and thus a reduction of pressure within the battery cell. For this purpose, such pressure equalization devices can, especially for so-called thermal events, have a bursting membrane that bursts when the internal cell pressure exceeds a threshold value, in order to allow the gas to escape from the battery cell.

[0005] Cylindrical battery cells can react very differently to a thermal event, deviating from their intended behavior by relieving pressure not only through the rupture membrane but also through the cell casing. This can occur, for example, if an opening provided by the pressure equalization device in the battery cell is closed by the cell winding, which can shift within the cell casing due to the thermal event. The uncontrolled escape of gas and heat through the cell casing can also trigger a thermal event in neighboring cells.

[0006] Against the background of this prior art, one objective of the present disclosure is to provide a device and a method, each of which is suitable for enriching the prior art and improving at least the aforementioned aspects of the prior art. In particular, it is the objective of the disclosure to provide a battery cell that reliably and precisely relieves pressure in the event of overpressure within the battery cell.

[0007] The problem is solved by the features of the independent claims. The dependent claims contain further developments of the disclosure.

[0008] The problem is then solved according to one aspect of the disclosure by a battery cell, in particular for an energy storage device for an electrically powered motor vehicle; wherein the battery cell has a cylindrical battery housing that defines an axial direction and a radial direction perpendicular to the axial direction; the battery cell has a cell winding arranged in the radial direction within the battery housing and comprising several layers; the battery cell has a winding insert; the winding insert is arranged in the radial direction within the cell winding; the winding insert is configured to be displaced along the axial direction when there is a pressure difference between an internal cell pressure and an ambient pressure;and the unwinding insert is designed to displace at least one radially inner layer of layers along the axial direction when the unwinding insert is displaced along the axial direction.

[0009] It is proposed to wind the electrodes onto the unwinding insert and secure them to the insert. In the event of a thermal event, the unwinding insert can be forced out of the battery cell as the internal cell pressure increases, by shifting the insert along the axial direction. In doing so, the unwinding insert can take the electrodes, or at least the inner layer, with it and thus unwind the cell winding from the inside out, advancing it along the axial direction. By systematically shifting the inner layer and / or layers of the cell winding, it is possible to prevent the electrodes or the cell winding from blocking a cell outlet and causing the internal cell pressure to rise to such an extent that the battery casing, for example, ruptures laterally. In this way, the battery cell can be reliably and precisely relieved of pressure, particularly in the event of a thermal event.

[0010] The battery cell can prevent undirected degassing during a thermal event, thus preventing a thermal event from being triggered in neighboring cells and the thermal event from being propagated through the energy storage device.

[0011] Optionally, the unwinding insert is designed to be at least partially pushed out of the battery housing. This allows the unwinding insert to be moved sufficiently far along the axial direction to engage the inner layer(s) to effectively prevent the cell winding from blocking an opening.

[0012] Optionally, the unwinding insert and the cell winding are mechanically connected at one end of the cell winding, relative to the axial direction. The unwinding shoulder can be attached to the end, i.e., a front end, of the electrodes to reliably shift the inner layer(s).

[0013] Optionally, the unwinding insert and at least the innermost layer of layers are mechanically connected. The unwinding step can then reliably move the innermost layer and / or multiple layers.

[0014] Optionally, the unwinding insert projects axially beyond the cell winding and radially beyond at least the innermost layer. This provides a reliable mechanical connection between the end of the cell winding and the unwinding insert. Through this positive and frictional connection, the unwinding shoulder can displace the innermost layer and / or multiple layers.

[0015] Optionally, when the unwinding insert is moved along the axial direction, several layers are shifted from the inside out, each along the axial direction. This allows the cell winding to be removed from the battery housing in a spiral shape.

[0016] Optionally, the unwinding insert has a cylindrical outer surface and is closed along the axial direction and / or at least partially fully cylindrical. For example, the unwinding insert is essentially hollow, open on one side, and closed in another manner. This allows the unwinding insert to be displaced by the pressure differential. Alternatively or additionally, the battery cell has a pressure equalization device mechanically connected to the unwinding insert. Alternatively or additionally, the unwinding insert has a porous outer surface and / or is porous at its ends.

[0017] According to one aspect of the disclosure, an energy storage device for an electrically powered motor vehicle is provided; the energy storage device comprising the battery cell as described in the disclosure. The battery cell may have one or more of the features described as optional and / or advantageous in order to achieve an associated technical effect.

[0018] According to one aspect of the disclosure, a motor vehicle is provided, the motor vehicle comprising the energy storage device according to the disclosure and / or at least one battery cell according to the disclosure. The energy storage device and / or the battery cell may have one or more of the features described as optional and / or advantageous in order to achieve an associated technical effect.

[0019] According to one aspect of the disclosure, a method for manufacturing a battery cell is provided, comprising: providing the battery casing, cell winding pre-products, and the unwinding insert; winding the cell winding pre-products around the unwinding insert to form the cell winding with the unwinding insert; and arranging the cell winding with the unwinding insert in the battery casing. The method can be carried out in such a way as to realize one or more of the features described as optional and / or advantageous in order to achieve an associated technical effect.

[0020] One embodiment of each is described below with reference to the figures. Fig. Figure 1 schematically shows a motor vehicle according to one aspect of the revelation; Fig. Figure 2 shows schematic cross-sectional views of a battery cell during thermal runaway; Fig. 3 schematic cross-sectional views of a battery cell according to one aspect of the disclosure during a thermal runaway; Fig. Figure 4 schematically shows a flowchart of a procedure according to one aspect of the revelation.

[0021] Fig. Figure 1 schematically shows a motor vehicle 50 according to one aspect of the disclosure. The motor vehicle 50 is a land vehicle. The motor vehicle 50 is a passenger car.

[0022] The motor vehicle 50 has an energy storage device 55 and an electric drive 52. The energy storage device 55 has a plurality of battery cells 56, the number of which is shown only schematically. The energy storage device 55 and / or the battery cells 56 are configured to be supplied with electrical energy in order to charge the battery cells 56, i.e., to increase the state of charge of the battery cells 56. The energy storage device 55 and / or the battery cells 56 are configured to provide electrical energy for operating the motor vehicle 50 and / or the electric drive 52, whereby the battery cells 56 are discharged, i.e., the state of charge of the battery cells 56 decreases.

[0023] Battery cell 56 is further related to Fig. 3 described.

[0024] Fig. Figure 2 schematically shows cross-sectional views of a battery cell 56 according to the prior art during thermal runaway. For this purpose, Fig. 2 divided into four sections (A), (B), (C) and (D), which illustrate a temporal sequence according to the order shown, with time passing from left, i.e. from section (A), to right, i.e. towards section (D).

[0025] The battery cell 56 is a cylindrical battery cell 56, thus having a battery housing 60 that defines an axial direction A and a radial direction R perpendicular to the axial direction A. The axial direction A corresponds to a winding axis.

[0026] The battery cell 56 has a cell winding 61 arranged in the battery housing 60 and a pressure equalization device 66. A cavity 71 is arranged within the cell winding 61 with respect to the radial direction R.

[0027] Section (A) illustrates a thermal event 70, for example caused by a particle and / or heterogeneity.

[0028] Section (B) illustrates that the thermal event 70 generates a gas which is transported upwards and downwards along the axial direction A along the electrodes of the cell winding 61. The battery cell 56 opens due to overpressure, i.e., an internal cell pressure that exhibits a pressure difference that is too large compared to the external pressure, and by means of the pressure equalization device 66, for example, via a rupture membrane. This creates an opening 67 in a base side (not shown) of the battery casing 60.

[0029] Section (C) illustrates that the cavity 71 collapses, as shown by the horizontally oriented arrows. This causes the cell winding 61 to close inwards in the radial direction R. The gas within the battery casing 60 and the collapsed cavity 71 displace the cell winding 61 downwards along the axial direction A. The cell winding 61 blocks the opening 67, as shown by the crossed arrow (see also Section (D)), thus preventing the gas from escaping. The internal cell pressure continues to rise; pressure builds up in the battery cell 56.

[0030] Section (D) illustrates that the battery cell 56 or its battery housing 60 opens laterally or on the outer side; this creates a defect 72 in the battery housing 60 and / or the cell winding 61.

[0031] Fig. Figure 3 schematically shows cross-sectional views of a battery cell according to section 56, an aspect of the disclosure, during thermal runaway. For this purpose, Fig. 3 is divided into five sections (A), (B), (C), (D) and (E), which illustrate a temporal sequence in the order shown, with time passing from left, i.e. from section (A), to right, i.e. towards section (E).

[0032] The battery cell 56 according to Fig. 3 is a battery cell 56, in particular for an energy storage device 55 for an electrically powered motor vehicle 50. Such an energy storage device 55 and such a motor vehicle 50 are related to Fig. 1 described. Such a battery cell 56 can also be used in other applications, such as mobile user devices and / or stationary applications. Fig. 3 is referred to Fig. 1 described.

[0033] The battery cell 56 according to Fig. 3 has a battery housing 60 that is at least partially cylindrical. The battery cell 56 is therefore a cylindrical cell. The cylindrical geometry of the battery housing 60, or of the battery cell 56, defines an axial direction A and, perpendicular to this, a radial direction R. The axial direction A corresponds to an axis of symmetry of the battery housing 60, or of the battery cell 56.

[0034] The battery cell 56 has a cell winding 61 with a positive electrode, a negative electrode, and separators (not shown). The cell winding 61 is arranged in the radial direction R within the battery housing 60.

[0035] The cell winding 61 has several layers 62. The layers 62 include, for example, electrodes and separators and are wound spirally with respect to a cross-section of the cell winding 61. Thus, the cell winding 61 has an inner layer 62a. The inner layer 62a is the layer within the cell winding 61 that is located closest to the axial direction A in the radial direction R.

[0036] The battery cell 56 has a pressure equalization device 66, also called a "vent". The pressure equalization device 66 is arranged on a base side of the battery housing 60. The pressure equalization device 66 is designed to equalize pressure when the pressure difference between the cell's internal pressure and the ambient pressure exceeds a limit value, for example by reducing the cell's internal pressure. This can be achieved, for instance, by relieving the battery cell 56 by expelling a gas from the battery cell 56. The pressure equalization device 66 may include a rupture diaphragm that is closed below the threshold and open above the threshold to achieve pressure equalization.

[0037] The battery cell 56 has a winding insert 65. The winding insert 65 is arranged radially R within the cell winding 61. The winding insert 65 thus extends along the axial direction A. The inner layer 62a contacts the winding insert 65. The layers 62 are thus supported by the winding insert 65 to prevent a cavity from collapsing under excessively high internal cell pressure. The winding insert 65 is made of an electrically insulating material and / or has an electrically insulating coating. The winding insert 65 is, for example, made of a plastic, such as polyethylene (PE), to be comparatively lightweight.

[0038] The unwinding insert 65 is designed to be displaced along the axial direction A by a pressure difference between the cell's internal pressure and the ambient pressure (see section (C)). The unwinding insert 65 is designed to be at least partially pushed out of the battery housing 60. The pressure difference pushes the unwinding insert 65 out of the battery housing 60.

[0039] The unwinding insert 65 is designed to displace at least the innermost layer 62a of the layers 62 along the axial direction A when the unwinding insert 65 is displaced along the axial direction A (see section (D)). In response to the pressure differential, not only is the unwinding insert 65 pushed out of the battery housing 60, but the unwinding insert 65 also takes at least the innermost layer 62a with it. Since the innermost layer 62a is connected to adjacent layers 62, or the adjacent layers 62 merge into one another, the innermost layer 62a takes with it an adjacent radially outer layer 62, which in turn can take with it another adjacent radially outer layer 62 (see figure (D)). Thus, by displacing the unwinding insert 65, the layers 62 are unwound spirally from the inside out and pushed out of the battery housing 60.When the unwinding insert 65 is moved along the axial direction A, several of the layers 62 are displaced from the inside out, each along the axial direction A. In other words, the unwinding insert is connected to the end 63 of the electrodes and is pushed outwards by the overpressure in the cell. In doing so, the unwinding insert 65 pulls the inner electrode winding or inner layer 62a along with it and gradually unwinds the electrode winding or cell winding 61 like a carnival snake.

[0040] The unwinding insert 65 and the cell winding 61 are mechanically connected to each other at an end 63 of the cell winding 61, arranged with respect to the axial direction A. The end 63 corresponds to a side of the cell winding 61. This allows the unwinding insert 65 to be mechanically connected to the cell winding 61 relatively easily, for example by gluing, a positive-locking and / or a force-locking connection.

[0041] The unwinding insert 65 and the inner layer 62a of the layers 62 are mechanically connected to each other. This allows the unwinding insert 65 to unwind the layers 62 from the inner layer 62a outwards in a spiral motion. Alternatively, the unwinding insert 65 can be connected to several layers 62 in order to move several layers 62 in the same manner.

[0042] The unwinding insert 65 projects beyond the cell winding 61 in the axial direction A and projects in the radial direction R beyond at least the inner layer 62a (not shown). In other words, the unwinding insert 65 can have a collar and / or plate in the region of the end 63 that projects beyond the inner layer 62a to allow the inner layer 62a to be displaced. The collar and / or plate can be porous in the region of the electrodes to facilitate filling with electrolytes.

[0043] To allow the unwinding insert 65 to be displaced by the pressure differential, it can be mechanically connected to the pressure equalization device 66 (not shown). Alternatively, the unwinding insert 65 has a cylindrical outer surface and is closed along the axial direction A and / or at least partially fully cylindrical. For example, the unwinding insert 65 can be closed at the top, i.e., in the region of the end 63, and open at the bottom.

[0044] Section (A) illustrates a thermal event 70, for example caused by a particle and / or heterogeneity.

[0045] Section (B) illustrates that the thermal event 70 generates a gas which is transported upwards and downwards along the axial direction A along the electrodes of the cell winding 61. The battery cell 56 opens due to overpressure, i.e., an internal cell pressure that exhibits a pressure difference that is too large compared to the external pressure, and by means of the pressure equalization device 66, for example, via a rupture membrane. This creates an opening 67 in a base side (not shown) of the battery casing 60.

[0046] Section (C) illustrates that the unwinding insert 65 is displaced downwards by the gas. The pressure difference between the cell's internal pressure and the ambient pressure also forces the unwinding insert 65 out of the battery housing 60, thus displacing it along the axial direction A.

[0047] Section (D) illustrates that the unwinding insert 65 pulls layers 62 or electrodes with it and unwinds the cell winding 61 in this way. First, the inner layer 62a is displaced along the axial direction A, followed by further layers 62 in the radial direction R outwards, starting from the inner layer 62a.

[0048] Section (E) illustrates that the battery cell 56 is relieved as intended via the pressure equalization device 66, for example the burst membrane, and the resulting opening 67.

[0049] In another embodiment (not shown), the battery cell 56 has a pressure equalization device 66 mechanically connected to the unwinding insert 65.

[0050] Fig. Figure 4 schematically shows a flowchart of a procedure 100 according to one aspect of the disclosure. The procedure 100 according to Fig. 4 is a method 100 for manufacturing a battery cell 56. Such a battery cell 56 is related to Fig. 1 and Fig. 3 described. Fig. 4 is referred to Fig. 1 and Fig. 3 described.

[0051] Procedure 100 according to Fig. 4 indicates: Providing 110 of the battery casing 60, of cell winding pre-products and of the unwinding insert 65.

[0052] The process 100 comprises: winding 120 of the cell winding pre-products around the unwinding insert 65 to form the cell winding 61 with the unwinding insert 65.

[0053] Method 100 comprises: Arranging 130 of the cell winding 61 with the unwinding insert 65 into the battery housing 60.

[0054] The expert recognizes that the procedure 100 according to Fig. 4. The procedure can also be carried out in a different order than shown. In particular, it is possible to swap, shift, repeat and / or perform steps of procedure 100 simultaneously. Reference symbol (part of the description) 50 motor vehicles 52 Drive 55 Energy storage device 56 battery cells 60 battery cases 61 cell wraps 62 Location 62a inner position 63 End 65 processing operation 66 Pressure equalization device 67 Opening 70 thermal event 71 Cavity 72 Defect 100 procedures 110 Provide 120 wraps 130 Order A axial direction R radial direction

Claims

[1] Battery cell (56) in particular for an energy storage device (55) for an electrically powered motor vehicle (50); wherein - the battery cell (56) has a cylindrical battery housing (60) which defines an axial direction (A) and a radial direction (R) perpendicular to the axial direction (A); - the battery cell (56) has a cell winding (61) arranged in the radial direction (R) inside the battery housing (60) and having several layers (62); - the battery cell (56) has a winding insert (65); - the unwinding insert (65) is arranged in the radial direction (R) within the cell winding (61); - the unwinding insert (65) is designed to be displaced along the axial direction (A) when there is a pressure difference between the cell's internal pressure and the ambient pressure; and - the unwinding insert (65) is designed to displace at least one layer (62a) of the layers (62) that is inner in the radial direction (R) along the axial direction (A) when the unwinding insert (65) is displaced along the axial direction (A). [2] Battery cell (56) according to claim 1, wherein - the unwinding insert (65) is designed to be at least partially pushed out of the battery housing (60). [3] Battery cell (56) according to claim 1 or 2, wherein - the unwinding insert (65) and the cell winding (61) are mechanically connected to each other at an end (63) of the cell winding (61) arranged with respect to the axial direction (A). [4] Battery cell (56) according to any of the preceding claims, wherein - the unwinding insert (65) and at least the inner layer (62a) of the layers (62) are mechanically connected to each other. [5] Battery cell (56) according to any of the preceding claims, wherein - the unwinding insert (65) extends beyond the cell winding (61) in the axial direction (A) and extends beyond at least the inner layer (62a) in the radial direction (R). [6] Battery cell (56) according to any of the preceding claims, wherein - when the unwinding insert (65) is moved along the axial direction (A), several of the layers (62) are moved from the inside out, each along the axial direction (A). [7] Battery cell (56) according to any of the preceding claims, wherein - the unwinding insert (65) has a cylindrical outer surface and is closed along the axial direction (A) and / or is at least partially fully cylindrical; - the battery cell (56) has a pressure equalization device (66) mechanically connected to the unwinding insert (65): and / or - the unwinding insert (65) has a porous outer surface and / or is porous at the ends. [8] Energy storage device (55) for an electrically powered motor vehicle (50), wherein the energy storage device (55) comprises a battery cell (56) according to one of the preceding claims. [9] Electrically powered motor vehicle (50), wherein the motor vehicle (50) comprises at least one battery cell (56) according to any one of the preceding claims 1 to 7 and / or an energy storage device (55) according to claim 8. [10] Method (100) for manufacturing a battery cell (56) according to any one of claims 1 to 7; wherein the method (100) comprises: - Provision (110) of the battery casing (60), cell winding pre-products and the unwinding insert (61); - Winding (120) the cell winding precursors around the unwinding insert (65) to form the cell winding (61) with the unwinding insert (65); and - Arranging (130) the cell winding (61) with the unwinding insert (65) into the battery housing (60).

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