SWEAT-FREE BIPOLAR SOLID-BODY BATTERY CELL

Abstract

Bipolar battery cell (100), comprising: a stack with N current collectors (118), M anode electrodes (110), S separators (116) and C cathode electrodes (114), where N, M, S and C are integers greater than 1; a first positioning element (130) that is arranged on one side of the stack and comprises: a first planar section (158); a first slot (131) in the first planar section (158), wherein a first of the C current collectors (118) extends through the first slot (131) in the first planar section (158) and is folded; a first rail section (154); and a second rail section (156), wherein the first rail section (154) and the second rail section (156) extend from the first planar section (158); and a first external tab (134) which is arranged between the first rail section (154) and the second rail section (156) and is connected to the first of the C current collectors (118).

Description

INTRODUCTION

[0001] The present invention relates to battery cells and in particular to bipolar battery cells.

[0002] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric motors and a battery system with one or more battery cells, modules, and / or packs. A power control system manages the energy supply to and from the battery system during charging, propulsion, and / or regeneration.

[0003] Bipolar solid-state battery cells with a stacked architecture can generate high output voltages (e.g., 12 V) in each cell. In this design, fewer current collectors are connected by welding to external tabs. Generally, only the outermost current collectors are connected. This type of connection is mechanically weaker and therefore has a shorter lifespan. Because fewer current collectors are connected to the external tabs, the current density on the welded sections of the bipolar solid-state battery cell is higher than in monopolar solid-state battery cells. This higher current density leads to hotspots, which reduce the battery's lifespan.

[0004] For further background information, reference is made to the publications US 2020 / 0 280 031 A1, US 2021 / 0 280 926 A1, DE 20 2014 105 400 U1 and US 2015 / 0 303 436 A1. SUMMARY

[0005] A bipolar battery cell comprises a stack of N current collectors, M anode electrodes, S separators, and C cathode electrodes, where N, M, S, and C are integers greater than 1. A first positioning element is arranged on one side of the stack and comprises a first planar section and a first slot in the first planar section. A first of the C current collectors extends through the first slot in the first planar section and is folded. The first positioning element also comprises a first rail section and a second rail section. The first rail section and the second rail section extend from the first planar section. A first external tab is arranged between the first rail section and the second rail section and is connected to the first of the C current collectors.

[0006] In other characteristics, the first slot extends in a direction parallel to the first and second rail sections. The first and second rail sections extend in a direction transverse to the stacking direction of the stack. The first slot extends in a direction transverse to the first and second rail sections. The first and second rail sections extend in a direction parallel to the stacking direction of the stack.

[0007] In other features, the first positioning element is made of an insulating material and contains a conductive layer that is positioned between the first rail section and the second rail section.

[0008] In other features, the first positioning element is made of a conductive material and includes an insulating material arranged on a surface of the first positioning element adjacent to the stack. The first external tab comprises a second planar section and a third section that is connected to and extends transversely to the second planar section.

[0009] In other features, the first positioning element also includes a multitude of slots. At least some of the other C current collectors extend through the multitude of slots in the first planar section and are folded.

[0010] In other features, the first external tab comprises an insulating substrate and a plurality of conductive layers arranged on one side of the insulating substrate. The plurality of conductive layers is connected to one of the plurality of C current collectors. Several conductive sections extend through the insulating substrate and are connected to one of the plurality of conductive layers, extending transversely to them.

[0011] In other features, a second positioning element is arranged on the opposite side of the stack and comprises a second planar section and a second slot in the second planar section. A second of the C current collectors extends through the second slot in the second planar section and is folded. The second positioning element comprises a third rail section and a fourth rail section, the third and fourth rail sections extending from the second planar section. A second external tab is engaged between the third and fourth rail sections and connected to the second of the C current collectors. The first and second of the C current collectors correspond to the outermost of the C current collectors.

[0012] In other features, the first planar section of the first positioning element includes a second slot in the first planar section. A second C current collector extends through the second slot in the first planar section and is folded transversely. A second external tab is arranged between the first rail section and the second rail section, and this tab is connected to the second C current collector. The first and second C current collectors correspond to the outermost C current collectors.

[0013] A bipolar battery cell comprises a stack of N current collectors, M anode electrodes, S separators, and C cathode electrodes, where N, M, S, and C are integers greater than 1. A first positioning element is arranged on one side of the stack and comprises a first planar section and a first slot in the first planar section. One of the C current collectors extends through the first slot in the first planar section and is folded. The first positioning element comprises a first rail section and a second rail section. The first rail section and the second rail section extend from the first planar section. A first external tab is arranged between the first rail section and the second rail section and is connected to the first of the C current collectors.A second positioning element is arranged on the opposite side of the stack and comprises a second planar section and a second slot in the second planar section. A second of the C current collectors extends through the second slot in the second planar section and is folded. The second positioning element comprises a third rail section and a fourth rail section, the third and fourth rail sections extending from the second planar section. A second external tab is engaged between the third and fourth rail sections and connected to the second of the C current collectors. The first and second of the C current collectors correspond to the outermost of the C current collectors.

[0014] In other characteristics, the first slot extends in a direction parallel to the first rail section and the second rail section. The first rail section and the second rail section extend in a direction perpendicular to the stacking direction of the stack.

[0015] In other characteristics, the first slot extends in a direction transverse to the first rail section and the second rail section. The first rail section and the second rail section extend in a direction parallel to the stacking direction of the stack.

[0016] In other features, the first positioning element is made of an insulating material and includes a conductive layer arranged between the first rail section and the second rail section. The first positioning element is made of a conductive material and includes an insulating material arranged on a surface of the first positioning element adjacent to the stack.

[0017] A bipolar battery cell comprises a stack of N current collectors, M anode electrodes, S separators, and C cathode electrodes, where N, M, S, and C are integers greater than 1. A first positioning element is arranged on one side of the stack and includes a first planar section and a first slot in the first planar section. One of the C current collectors extends through the first slot in the first planar section and is folded. The first positioning element includes a second slot in the first planar section. A second of the C current collectors extends through the second slot in the first planar section and is folded. The first positioning element also includes a first rail section and a second rail section. The first rail section and the second rail section extend from the first planar section.A first external tab is arranged between the first rail section and the second rail section and is connected to the first of the C current collectors. A second external tab is arranged between the first and second rail sections and is connected to the second of the C current collectors. The first and second of the C current collectors correspond to the outermost of the C current collectors. The first slot extends in a direction parallel to the first and second rail sections. The first and second rail sections extend in a direction transverse to the stacking direction of the stack.

[0018] In other characteristics, the first slot extends in a direction transverse to the first rail section and the second rail section. The first rail section and the second rail section extend in a direction parallel to the stacking direction of the stack.

[0019] In other features, the first positioning element is made of an insulating material and includes a conductive layer arranged between the first rail section and the second rail section. The first positioning element is made of a conductive material and includes an insulating material arranged on a surface of the first positioning element adjacent to the stack.

[0020] Further applications of the present invention will become apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples serve only for illustration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will become more fully apparent from the detailed description and the accompanying drawings, whereby the following applies: Fig. 1 is a side cross-sectional view of a monopolar solid-state battery; Fig. 2 is a side cross-sectional view of a bipolar solid-state battery; Fig. 3A is a side cross-sectional view of an example of a bipolar solid-state battery with a positioning element having rail sections extending transversely to a stacking direction according to the present invention; Fig. Figure 3B is a perspective view showing an example of an external tab according to the present invention; Fig. Figure 4 is a perspective view showing an example of a positioning element according to the present invention; Fig. 5A and Fig. Figure 5B shows side views illustrating examples of positioning elements according to the present invention; Fig. Figure 6 is a perspective view showing another example of a bipolar solid-state battery having a positioning element with rail sections extending in a stacking direction according to the present invention; Fig. Figure 7 is a side cross-sectional view of another example of a bipolar solid-state battery in a symmetrical configuration according to the present invention; Fig. Figure 8 is a side cross-sectional view of another example of a bipolar solid-state battery in an asymmetric configuration according to the present invention; Fig. Figure 9 is a side cross-sectional view of an example of a bipolar solid-state battery in a symmetrical configuration according to the present invention; Fig. Figure 10 is a side cross-sectional view of another example of a positioning element according to the present invention; and Fig. Figure 11 is a perspective view showing another example of an external tab according to the present invention.

[0022] Reference numbers can be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0023] Although the battery cells according to the present invention are described in connection with use in a vehicle, the battery cells can also be used in non-vehicle applications.

[0024] In the Fig. 1 and Fig. Figure 2 shows a monopolar or bipolar solid-state battery cell. Fig. 1. A battery cell 50 has a monopolar or parallel configuration. The battery cell 50 is shown to comprise anode electrodes 60-1, 60-2, 60-3 and 60-4 (collectively or individually anode electrode(s) 60), cathode electrodes 64-1, 64-2, 64-3 and 64-4 (collectively or individually cathode electrode(s) 64), separators 66 and current collectors 68-1, 68-2, 68-3, 68-4 and 68-5 (collectively or individually current collector(s) 68).

[0025] The battery cell 50 also contains a casing 74, for example, a plastic encapsulation layer. An external tab 76 establishes a connection between the current collectors 68-1, 68-3 and 68-5 and a positive busbar 78. An external tab 80 establishes a connection between the current collectors 68-2 and 68-4 and a negative busbar 82.

[0026] Battery cell 50 contains the current collector 68-1, which is arranged next to the anode electrode 60-1. The separator 66 is arranged between the anode electrode 60-1 and the cathode electrode 64-1. The current collector 68-2 is arranged next to the cathode electrode 64-1. Then the pattern is reversed. The cathode electrode 64-2 is arranged next to the current collector 68-2. The separator 66 is arranged next to the cathode electrode 64-2. The anode electrode 60-2 is arranged next to the separator 66. The separator 66 is arranged next to the anode electrode 60-2. Then the pattern is repeated.

[0027] In Fig. Figure 2 shows a battery cell 88 configured in a bipolar or series configuration. The battery cell 88 is shown to include anode electrodes 90-1, 90-2, 90-3 and 90-4 (collectively or individually anode electrode(s) 90), cathode electrodes 94-1, 94-2, 94-3 and 94-4 (collectively or individually cathode electrode(s) 94), separators 96 and current collectors 98-1, 98-2, 98-3, 98-4 and 98-5 (collectively or individually current collector(s) 98).

[0028] The battery cell 88 contains the current collector 98-1, which is arranged next to the anode electrode 90-1. The separator 96 is arranged between the anode electrode 90-1 and the cathode electrode 94-1. The current collector 98-2 is arranged next to the cathode electrode 94-1. The pattern then repeats.

[0029] As can be seen, both include Fig. 1 as well Fig. 2N = 4 cathode and anode electrodes and N + 1 current collectors. Depending on the application, additional or fewer electrodes and current collectors can be used. As can be seen from the comparison of Fig. 1 and Fig. As shown in Figure 2, in the bipolar configuration fewer current collectors are connected to the external tab corresponding to the positive supply line than in the monopolar configuration (e.g., 1 vs. 3 in this example). In the bipolar configuration, compared to the monopolar configuration, fewer current collectors are connected to the external tab corresponding to the negative supply line (e.g., 1 vs. 2 in this example).

[0030] Advantages of the bipolar configuration include higher power and higher output voltage from a single battery cell. Disadvantages include greater tensile stress on weld joints in the bipolar configuration compared to the monopolar configuration. There are fewer current collector layers to withstand the external force, making the connection less robust. In high-current applications (e.g., cold starts at 10°C or fast charging), the current density (along with a high output potential) also causes hot spots on the welded section in the bipolar configuration, reducing durability.

[0031] In the Fig. Figures 3A to 5B show an example of a bipolar battery cell 100. In some examples, the bipolar battery cell 100 is implemented using solid-state technology. Fig. 3A is the bipolar battery cell 100 configured in a bipolar or series configuration. The bipolar battery cell 100 is shown to include anode electrodes 110-1, 110-2, 110-3 and 110-4 (collectively or individually anode electrode(s) 110), cathode electrodes 114-1, 114-2, 114-3 and 114-4 (collectively or individually cathode electrode(s) 114), separators 116 and current collectors 118-1, 118-2, 118-3, 118-4 and 118-5 (collectively or individually current collector(s) 118).

[0032] The bipolar battery cell 100 contains the current collector 118-1, which is arranged next to the anode electrode 110-1. The separator 116 is arranged between the anode electrode 110-1 and the cathode electrode 114-1. The current collector 118-2 is arranged next to the cathode electrode 114-1. The pattern then repeats.

[0033] The bipolar battery cell 100 contains a casing 128, e.g., a plastic encapsulation layer. A positioning element 130 is arranged on the upper and lower sides of the anode electrodes 110 and the cathode electrodes 114. Fig. 3A and Fig. 3B the current collector 118-1 is guided through a slot 131 in the positioning element 130, and one end of it is folded (e.g. transversely).

[0034] An external tab 134 is arranged in contact with the current collector 118-1. The external tab 134 comprises a first planar section 136 (which extends into Fig. 3 extends horizontally), which is in contact with the end of the current collector 118-1. In some examples, the first planar section 136 has a thickness in the range of 0.08 mm to 2 mm.

[0035] The external tab 134 includes a second section 138, which extends transversely (or vertically in Fig. 3A) extends to the first planar section 136. A third section 140 of the external tab 134 extends transversely (or horizontally in Fig. 3) to the second section 138 and is connected to the positive busbar 142.

[0036] The current collector 118-5 is guided through the slot 131 in the positioning element 130 (on the underside of the battery cell), and one end of it is folded (e.g., transversely). An external tab 144 is arranged in contact with the current collector 118-1. The external tab 144 comprises a first planar section 146 (which extends into Fig. 3A extends horizontally), which is in contact with the end of the current collector 118-5. The external tab 144 includes a second section 148, which extends transversely (or vertically in Fig. 3A) extends to the first planar section 146. A third section 150 of the external tab 144 extends transversely (or horizontally in Fig. 3A) to the second section 148 and is connected to the negative busbar 152.

[0037] In the Fig. Figures 3A and 4 to 5B show examples of positioning element 130. Fig. 3A and Fig. Figure 4 shows the positioning element 130 with a "C"-shaped cross-section. The positioning element 130 comprises a first rail section 154 and a second rail section 156 located at its opposite ends, and an intermediate planar section 158. In some examples, the first rail section 154 and the second rail section 156 are located along the shorter sides of the battery cell, as shown. In other words, the first rail section 154 and the second rail section 156 extend in a direction transverse to the stacking direction. In other examples, the first rail section 154 and the second rail section 156 are located along longer sides of the battery cell (and extend in a direction parallel to the stacking direction). Fig. 6) In some examples, the slot 131 is arranged in the planar section 158 next to the first rail section 154 or the second rail section 156 and extends in a direction parallel to it.

[0038] In some examples, the slot 131 has a width ranging from 10 µm to 1000 µm. In some examples, the slot 131 extends over a predetermined distance that is less than or equal to the width of the current collectors in a direction perpendicular to the stacking direction. In some examples, the height of the first and second rail sections is in the range of 0.1 mm to 2 mm, although other values ​​may also be used.

[0039] In Fig. 5A is a body 169 of the positioning element 130 made of an insulating material and contains a conductive layer 170 between the rail sections along a top surface of the planar section 158. In some examples, the insulating material is selected from a group consisting of plastic, polyolefin such as polypropylene, polytetrafluoroethylene (PTFE), or another suitable insulating material.

[0040] In Fig. 5B the body 169 of the positioning element 130 is made of a conductive material and contains, in addition to the planar section 158, a non-conductive section 172 along the underside of the positioning element 130.

[0041] As in Fig. As shown in Figure 6, the first rail section 154 and the second rail section 156 can also extend in the stacking direction of a battery cell 184. As can be seen, the slot 131 extends transversely between the first rail section 154 and the second rail section 156 and not, as shown above, parallel to the first and second rail sections. In some examples, conductive adhesives are used to improve the conductive contact.

[0042] Among the advantages of the weld-free bipolar battery cell is its mechanical robustness. A larger contact area increases the permissible current density. The weld-free bipolar battery cell offers improved contact surfaces between the current collectors and the external terminals. The weld-free bipolar battery cell protects the bipolar current collectors from touching each other, thus preventing short circuits.

[0043] The Fig. 7 and Fig. Figure 8 shows that symmetric and asymmetric configurations can be used. Fig. 7. A battery cell 200 has a symmetrical configuration with positive and negative terminals located on opposite sides of the battery cell 200. In Fig. In Figure 8, a battery cell 250 has an asymmetrical configuration with positive and negative terminals on the same side of the battery cell 250. The conductive layer 170 is divided into a first section 170-1 and a second section 170-2, which are not electrically connected to each other. In some examples, the distance between the first section 170-1 and the second section 170-2 is sufficient to prevent conductive contact between the current collectors 118-1 and 118-5 when folded. A connector 258 comprises an insulating substrate 262, a first and a second external tab 260 and 270, which are connected to the current collector 118-1 and the current collector 118-5, respectively, by conductive plates 274 and 276.

[0044] In the Fig. 9 and Fig. In the 10th case, the battery cells described above are configured bipolarly. Therefore, the voltages from one side of the battery cell (connected to ground or another reference potential) sum to the opposite side of the battery cell. Fig. 9 contains a battery cell 300 and several external tabs connected to current collectors 118-1 to 118-4. Current collector 118-5 is connected to ground. In Fig. 10 Conducting sections 310-1, 310-2, 310-3 and 310-4 (together the conducting sections 310) are arranged on a surface of the third section 150 and are isolated from the adjacent conducting sections 310 to allow separate connections with them.

[0045] In Fig.Figure 11 shows an external connection 410 with multiple reference tabs, which contains an insulating substrate 414. The conductive layers 418-1, 418-2, 418-3 and 418-4 are spaced apart from each other and extend between the sides of the insulating substrate 414 along its base surface.

[0046] The conductive sections 422-1, 422-2, 422-3, and 422-4 extend through the insulating substrate 414 and are connected to the conductive layers 418-1, 418-2, 418-3, and 418-4, respectively. A sealing layer 424 extends along the lower portions of the conductive tab sections 422-1, 422-2, 422-3, and 422-4. As can be seen, the conductive tab sections 422-1, 422-2, 422-3, and 422-4 can be used to monitor voltages at collectors within the battery cell (e.g., 12 V, 9 V, 6 V, and 3 V for a 12 V bipolar battery cell).

[0047] As can be seen, the conductive tab sections 422-1, 422-2, 422-3 and 422-4 provide additional reference tabs between the bipolar cell units to monitor the voltage status and the technical condition (SOH or state of health) of the battery.

Claims

[1] Bipolar battery cell (100), comprising: a stack with N current collectors (118), M anode electrodes (110), S separators (116) and C cathode electrodes (114), where N, M, S and C are integers greater than 1; a first positioning element (130) that is arranged on one side of the stack and comprises: a first planar section (158); a first slot (131) in the first planar section (158), wherein a first of the C current collectors (118) extends through the first slot (131) in the first planar section (158) and is folded; a first rail section (154); and a second rail section (156), wherein the first rail section (154) and the second rail section (156) extend from the first planar section (158); and a first external tab (134) which is arranged between the first rail section (154) and the second rail section (156) and is connected to the first of the C current collectors (118). [2] Bipolar battery cell (100) according to claim 1, wherein: the first slot (131) extends in a direction parallel to the first rail section (154) and the second rail section (156); and the first rail section (154) and the second rail section (156) extend in a direction transverse to a stacking direction of the stack. [3] Bipolar battery cell (100) according to claim 1, wherein: the first slot (131) extends in a direction transverse to the first rail section (154) and to the second rail section (156); and the first rail section (154) and the second rail section (156) extend in a direction parallel to a stacking direction of the stack. [4] Bipolar battery cell (100) according to claim 1, wherein the first positioning element (130) is made of an insulating material and includes a conductive layer (170) arranged between the first rail section (154) and the second rail section (156). [5] Bipolar battery cell (100) according to claim 1, wherein the first positioning element (130) is made of a conductive material and includes an insulating material arranged on a surface of the first positioning element (130) adjacent to the stack. [6] Bipolar battery cell (100) according to claim 1, wherein the first external tab (134) comprises: a second planar section (136); and a third section (138) which is connected to the second planar section (158) and extends transversely to it. [7] Bipolar battery cell (100) according to claim 1, wherein the first positioning element (130) further comprises a plurality of slots and wherein at least some of the other C current collectors (118) extend through the plurality of slots in the first planar section (158) and are folded. [8] Bipolar battery cell (100) according to claim 7, wherein the first external tab (134) comprises: an insulating substrate (414); a plurality of conductive layers (418) arranged on one side of the insulating substrate (414), wherein the plurality of conductive layers (418) is connected to one of the plurality of C current collectors (118); and a plurality of conductive sections (310) extending through the insulating substrate (414) and connected to one of the plurality of conductive layers (418) and extending transversely to them. [9] Bipolar battery cell (100) according to claim 1, further comprising: a second positioning element (130) which is arranged on an opposite side of the stack and comprises: a second planar section (158); a second slot (131) in the second planar section (158), wherein a second of the C current collectors (118) extends through the second slot (131) in the second planar section (158) and is folded; a third rail section (154); and a fourth rail section (156), wherein the third rail section (154) and the fourth rail section (156) extend from the second planar section (158); and a second external tab (144) which engages between the third rail section (154) and the fourth rail section (156) and is connected to the second of the C current collectors (118), wherein the first of the C current collectors (118) and the second of the C current collectors (118) correspond to the outermost of the C current collectors (118). [10] Bipolar battery cell (100) according to claim 1, wherein: the first planar section (158) of the first positioning element (130) has a second slot (131) in the first planar section (158); a second of the C current collectors (118) extends through the second slot (131) in the first planar section (158) and is folded in the transverse direction; and a second external tab (144) is arranged between the first rail section and the second rail section and is connected to the second of the C current collectors (118), wherein the first of the C current collectors (118) and the second of the C current collectors (118) correspond to the outermost of the C current collectors (118).

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