A battery cell for an electrical storage device of an at least in part electrically operated motor vehicle, as well as a method for producing a battery cell

Abstract

A battery cell (10, Fig 1) for an electrical storage device of an electric or hybrid vehicle, comprises at least a positive electrode 24, a negative electrode 22, and a separator 26, wherein the positive electrode 24 is a first layer, the separator 26 is a second layer, and the negative electrode 22 is a third layer of a layer sandwich 48, rolled into a jelly roll 20 of the battery cell, the separator 26 comprising at least a first adhesive layer 34 on at least a first edge 36. The separator may comprise a second adhesive layer 38 on a second edge opposite the first edge. The size of the separator may exceed the negative electrode. The negative electrode may exceed the positive electrode in size. The adhesive layer may be a polymer material. The adhesive layer may be applied adjacent to the first terminal of the battery cell. The method for producing the battery cell may comprise inserting the jelly roll into a can and melting the first and second terminal caps on the can.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of automobiles. More specifically, the present invention relates to a battery cell for an electrical storage device of an at least in part electrically operated motor vehicle according to independent claim 1. Furthermore, the present invention relates to a method for producing a battery cell. BACKGROUND INFORMATION

[0002] During cylindrical cell assembly, a jelly roll is inserted into a can housing, terminal caps are placed to cover the opening, and the caps are welded by laser welding from outside of the cell. The laser welding has to occur through the terminal cap, which requires a high-power laser to be used. Although the laser type, power, and duration may be optimized to minimize any process risk, there is always process tolerance and deviation that may lead to conditions where laser welding debris such as fumes and particles are generated within the sealed can. The particles can drop down into the jelly roll below and in between the cathode / separator / anode interface. The foreign particle can potentially cause internal short circuit as the jelly roll undergoes swelling throughout formation and extended cycling. With jelly roll swelling, the compressive stress increases, thereby potentially causing the foreign particle to rip through separator and cause an internal short circuit, which may lead to a catastrophic thermal runaway event.

[0003] Because the battery is composed of metal components and the welding debris may be small, it is difficult to detect with x-ray and / or high-speed CT scans. It is also a costly quality control step. SUMMARY OF THE INVENTION

[0004] It is an object of the present invention to provide a battery cell as well as a method for producing a battery cell, by which an improved battery cell can be provided.

[0005] This object is solved by a battery cell as well as a method for producing a battery cell according to the independent claims. Advantageous embodiments are presented in the dependent claims.

[0006] One aspect of the invention relates to a battery cell for an electrical storage device of an at least in part electrically operated motor vehicle, comprising at least a positive electrode, a negative electrode and a separator, wherein the positive electrode is a first layer, the separator is a second layer, and the negative electrode is a third layer of a layer sandwich, and wherein the layer sandwich is rolled to a jelly roll of the battery cell.

[0007] According to an embodiment, the separator comprises at least a first adhesive layer on at least a first edge of the separator.

[0008] Therefore, the proposed solution attempts to alter the cell design that shields the welding debris from entering within the jelly roll by applying an adhesive laminate layer on at least one edge of the separator.

[0009] The proposed solution may include a polymer separator and an adhesive layer composed of single layer or multi-layer polymer and / or single- or double-sided ceramic coating with a thermosetting polymer adhesive that is inactive with electrolyte and high potentials, for example similar functions like PVDF, PAA or furthermore, on the edge parallel to the machine direction.

[0010] The ceramic coating can be implemented with a solution-processed method where at least one edge of the separator is dipped into the solution bath of melted adhesive or can be spray casted. The coating may then be dried to remove the solvent, to leave behind the adhesive layer only on the edge of the separator. This edge may be laminated together after the jelly roll has been wound.

[0011] According to an embodiment the separator comprises a second adhesive layer on a second edge of the separator, wherein the second edge is opposing the first edge.

[0012] In another embodiment, the size of separator exceeds the size of the negative electrode. For example, the length of the sides of the separator is greater than the length of the sides of the negative electrode.

[0013] In another embodiment the size of the negative electrode exceeds the size of the positive electrode. For example, the length of the sides of the negative electrode may be equal to or greater than the length of the sides of the positive electrode.

[0014] In another embodiment the adhesive layer is a polymer material.

[0015] According to another embodiment the adhesive layer is applied next to a first terminal of a positive electrode of the battery cell.

[0016] A further aspect of the invention relates to a method for producing a battery cell according to the preceding aspect. A jelly roll with a layer sandwich is provided. A can of the battery cell is provided. A first terminal cap and a second terminal cap of the battery is provided. The jelly roll is inserted in the can and the first terminal cap and a second terminal cap is melted on the can.

[0017] Advantageous embodiments of the battery cell are to be regarded as advantageous embodiments of the method.

[0018] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The novel features and characteristic of the disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0020] The drawings show in:

[0021] Fig. 1 a schematic perspective view according to an embodiment of a battery cell;

[0022] Fig. 2 a schematic view according to an embodiment of a jelly roll;

[0023] Fig. 3A a schematic perspective view according to an embodiment of a separator for a jelly roll;

[0024] Fig. 3B another schematic perspective view according to an embodiment of the separator for the jelly roll; and

[0025] Fig. 4 another schematic view according to an embodiment of the jelly roll for a battery cell.

[0026] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0027] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0028] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0029] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device, or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0030] In the following detailed description of the embodiment of the disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0031] Fig. 1 shows a schematic perspective view according to an embodiment of a battery cell 10. The battery cell 10 comprises at least a can 12, a first terminal cap 14 as well as a first terminal 16 and a second terminal 50 (not shown in Fig. 1) as shown in Fig. 4. Furthermore, the battery cell 10 comprises an interior 18. In the interior 18, a jelly roll 20 is inserted.

[0032] Fig. 2 shows a schematic view according to an embodiment of the jelly roll 20. In particular, the jelly roll 20 shown in Fig. 2 is not wound and is a layered sandwich 48. Fig. 2 shows that the jelly roll 20 comprises a positive electrode or cathode 24, a negative electrode or anode 22, a separator 26, cathode active material 42, anode active material 28, a copper tab 30 for a second terminal 50 (not shown) as well as an aluminum tab 32 for a first terminal 16 (not shown). For a tab design, aluminum tab 32 may be connected to the first terminal 16, and the copper tab 30 may be connected to the second terminal 50. For a tabless design, the first terminal 16 may be aluminum and the second terminal 50 may be copper.

[0033] Furthermore Fig. 2 shows that the separator 26 may comprise a first adhesive layer 34 on a first edge 36. Furthermore, the separator 26 may comprise a second adhesive layer 38, in particular at a second edge 40.

[0034] In particular Fig. 2 shows that the jelly roll 20 of a battery cell 10 is in particular configured for an electrical storage device of an at least in part electrically operated motor vehicle. The battery cell 10 comprises at least the positive electrode or cathode 24, the negative electrode or anode 22, and a separator 26, wherein the positive electrode 22, is a first layer, the separator 26 is a second layer, and the negative electrode 24 is a third layer of a layer sandwich 48 rolled to a jelly roll 20 of the battery cell 10. In particular, the separator 26 includes at least the first adhesive layer 34 on at least the first edge 36 of the separator 26. The first edge 36 may be connected to an aluminum tab 32 for the positive electrode 24. The positive electrode comprises the cathode active material 42.

[0035] Furthermore, Fig. 2 shows, that the separator 26 may include a second adhesive layer 38 on the second edge 40 of the separator 26, wherein the second edge 40 is opposing the first edge 36. The second edge 40 may be connected to a copper tab 30 for the negative electrode 22. The negative electrode 22 comprises the anode active material 28.

[0036] Furthermore, Fig. 2 shows, that the size of the separator 26 may exceed the size of the negative electrode 22. For example, the length of the sides of the separator is greater than the length of the sides of the negative electrode. Furthermore, the size of the negative electrode 22 may exceed the size of the positive electrode 24. For example, the length of the sides of the negative electrode may be equal to or greater than the length of the sides of the positive electrode.

[0037] In particular, Fig. 2 shows a cell design that shields the welding debris 44 (Fig. 4) such as spatter, fumes, and foreign particles from entering within the jelly roll 20 by applying the adhesive layer 34, 38 on the edge 36, 40 of the separator 26.

[0038] The separator 26 may comprise a polymer separator, and the adhesive layers 34, 38 may include a polymer material as well. The polymer material may be composed of single layer or multi-layer polymer and / or single-sided or double-sided ceramic coating with a thermosetting polymer adhesive that is inactive with electrolyte and high potentials on the edge 36, 40 parallel to the machine direction.

[0039] The single-side or double-sided ceramic coating can be implemented with a solution processed method where the first edge 36 and / or second edge 40 of the separator 26 is dipped into the solution bath of melted adhesive or can be spray casted. The coating is then dried to remove the solvent and to leave behind the adhesive layer 34, 38 on the edge 36, 40 of the separator 26. The edge 36, 40 may be laminated together after the jelly roll 20 has been wound.

[0040] The cylindrical battery cell 10 may include the jelly roll 20, and the jelly roll 20 is designed to be a tightly wound version of the positive electrode 22, the separator 26, and the negative electrode 24 where the separator 26 has a defined overhang exceeding the size of both the positive electrode 24 and the negative electrode 22. The positive electrode 24 may be smaller than the negative electrode 22. The negative electrode 22 may be smaller than the separator 26 to ensure a favorable n / p ratio is maintained and also to ensure that there is sufficient separator overhang to prevent electric contact issues such as shorting between the negative and positive electrodes 22, 24.

[0041] Prior to winding of the jelly roll 20, the edges 36, 40 of the layered sandwich 48 may be laminated with a rolling heat press to thermoset the polymer adhesive layers 34, 38 on the edges 36, 40 of the separator 26 thereby laminating the edges 36, 40 of the separator.

[0042] This forms a physical barrier to keep potential welding debris 44 such as spatter and fumes from entering the jelly roll 20 interior during laser welding assembly.

[0043] The adhesive layer 34, 38 may not need to be applied at both edges 36, 40, but for the positive electrode 24, the first edge 36 must be covered at the first terminal 16 with the aluminum tab 32 because aluminum is much harder to weld than copper. Since the aluminum tab 32 is harder to weld compared to the copper tab 30, the high powers may lead to more welding debris 44 that may include more spatter / fume formation.

[0044] For the negative electrode 22, the second edge 40 must be covered by the second terminal 50 with the copper tab 30.

[0045] The benefits of the present invention lies in better quality control and removing potential issues from the manufacturing process and effects analysis. By reducing the likelihood of welding debris 44 from entering the jelly roll 20, the likelihood of a welding debris 44 penetrating the separator to short circuit and cause the cell to undergo thermal runaway may be reduced, which in turn will reduce likelihood of electric vehicle recall..

[0046] Fig. 3A shows a schematic view according to an embodiment of the separator 26 for the jelly roll 20, a first adhesive layer 34 deposited on a first edge 36 of the separator 26, and a second adhesive layer 38 deposited on a second edge 40 of the separator 26. In particular, the separator 26 with the adhesive layer 34, 38 is shown, and to transport the separator 26 for manufacturing, the separator 26 may be transported in rolls as shown.

[0047] Fig. 3B shows another schematic view according to an embodiment of the the separator 26 for the jelly roll 20. The cross-section of the first adhesive layer 34 deposited on the first edge 36 of the separator 26, and the second adhesive layer 38 deposited on the second edge 40 of the separator 26. The first adhesive layer 34 and / or the second adhesive layer 38 may be applied to both sides of the separator 26 as shown in Fig. 3B or may be applied around the entire edge of the separator 26 (not shown).

[0048] Fig. 4 shows a schematic side view according to an embodiment of a jelly roll 20 battery cell 10. In particular Fig. 4 shows that in the lower part of Fig. 4 the fumes of the welding debris 44 can be intercepted by the first adhesive layer 34 that may be applied on the first edge 36 with the positive electrode or cathode 24. The blocking of the welding debris 44 with the first adhesive layer 34 from welding an aluminum tab 32 may prevent debris 44 from being sealed after a first terminal 16 and a first terminal cap 14 is applied.

[0049] Fig. 4 also shows that in the upper part of Fig. 4 the fumes of the welding debris 44 can be intercepted by the second adhesive layer 38 that may be applied on the second edge 40 with the negative electrode or anode 22. The blocking of the welding debris 44 with the second adhesive layer 38 from welding a copper tab 30 may prevent debris 44 from being sealed after a second terminal 50 and a second terminal cap 46 is applied.

[0050] The first adhesive layer 34 may be applied adjacent to the first terminal 16, and the first terminal cap 14 may be melted to the can 12. The second adhesive layer 38 may be applied adjacent to the second terminal 50, and the second terminal cap 46 may be melted to the can 12. Reference Signs 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 battery cell can first terminal cap first terminal interior jelly roll negative electrode or anode positive electrode or cathode separator anode active material copper tab aluminum tab first adhesive layer first edge second adhesive layer second edge cathode active material welding debris second terminal cap layered sandwich second terminal

Claims

1. A battery (10) cell for an electrical storage device of an at least in part electrically operated motor vehicle, comprising at least a positive electrode (24), a negative electrode (22), a separator (26), wherein the positive electrode (24) is a first layer, the separator (26) is a second layer, and the negative electrode (22) is a third layer of a layer sandwich (48), and wherein the layer sandwich (48) is rolled to a jelly roll (20) of the battery cell (10), characterized in thatat the separator (26) comprises at least a first adhesive layer (34) on at least a first edge (36) of the separator (26).

2. The battery cell (10) according to claim 1, characterized in thatthe separator (26) comprises a second adhesive layer (38) on a second edge (40) of the separator (26), wherein the second edge (40) is opposing the first edge (36).

3. The battery cell (10) according to claim 1 or 2, characterized in thatthe size of the separator (26) exceeds the size of the negative electrode (22).

4. The battery cell (10) according to any one of claims 1 to 3, characterized in thatthe size of the negative electrode (22) exceeds the size of the positive electrode (24).

5. The battery cell (10) according to any one of claims 1 to 4, characterized in thatthe adhesive layer (34, 38) is a polymer material.

6. The battery cell (10) according to any one of claims 1 to 5, characterized in thatthe adhesive layer (34, 38) is applied adjacent to a first terminal (16) of the battery cell (10).

7. A method for producing a battery cell (10) according to any one of claims 1 to 6, comprising the steps of:- providing a jelly roll (20) with a layer sandwich (48);- providing a can (12) of the battery cell (10);- providing a first terminal cap (14) and a second terminal cap (46) of the battery cell (10);- inserting the jelly roll (20) in the can (12); and- melting the first terminal cap (14) and the second terminal cap (46) on the can (12).12

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