Cell winding for a lithium-ion battery cell, lithium-ion battery cell, energy storage

Abstract

Cell coil (2) for a lithium-ion battery cell (1), with an anode strip and a cathode strip as electrode strips (4, 5), and with a separator strip (8) arranged between the electrode strips (4, 5), wherein the electrode strips (4, 5) are aligned at right angles to one another in their longitudinal extent and are folded alternately over one another, wherein the separator strip (8) is carried along with one of the electrode strips (4, 5) and has a plurality of separator sections (18) each lying between the superimposed electrode sections (10, 11) of the electrode strips (4, 5), which are connected to one another by folding sections (17), and wherein the separator strip (8) is designed as a flexible separator tube (9) which envelops the one electrode strip (4, 5) when viewed in cross-section, characterized inthat the successive separator sections (18) of the separator strip (8) alternately protrude on one of their longitudinal sides with a protective section (14) at least beyond the respective electrode section (10, 11) of the other of the electrode strips (4, 5).

Description

[0001] The invention relates to a cell coil for a lithium-ion battery cell, comprising an anode strip and a cathode strip as electrode strips, and comprising a separator strip arranged between the electrode strips, wherein the electrode strips are aligned at right angles to one another in their longitudinal extent and are alternately folded over one another, and wherein the separator strip is carried along with one of the electrode strips and has a plurality of separator sections each lying between the superimposed electrode sections of the electrode strips, which separator sections are connected to one another by deformable folding sections.

[0002] Furthermore, the invention relates to a lithium-ion battery cell for an energy storage device of a motor vehicle, which is designed in particular as a traction battery, with a housing in which at least one cell coil described above is arranged and can be electrically contacted.

[0003] Furthermore, the invention relates to an energy storage device with at least one such battery cell and to a method for producing the above-mentioned cell coil for a lithium-ion battery cell.

[0004] Cell coils of the type mentioned above are already known from the prior art. In particular, published patent application US 5,618,318 A discloses a cell coil for a battery cell comprising two electrode strips placed on top of each other at right angles to each other in their longitudinal extension and folded alternately over each other, resulting in a cell stack with superimposed electrode sections of the electrode strips. To prevent direct electrical contact between the electrode strips or electrode sections, a separator strip is provided, which is wound along with one of the electrode strips, so that a separator section of the separator strip lies between each two superimposed electrode sections. In particular, the separator strip protects only the electrode strip with which it is carried.

[0005] US Pat. No. 9,548,496 B2 discloses another cell coil in which several electrode sections are separated from the electrode strips by separator sections. EP 2 135 310 B1 also describes a cell coil with electrode strips folded over one another. In this case, the electrode strips are not perpendicular to each other, but rather parallel to each other in their longitudinal extension and are each wound in an S-shape.

[0006] An electrode arrangement comprising a layered structure with at least two electrodes and an intermediate separator is also already known from published patent application DE 10 2013 019 071 A1. Another cell coil of this type is also known from published patent application US 6,245,461 B1. Such cell coils are also already known from published patent applications US 2014 / 0272537 A1, US 2017 / 0149092 A1, US 5,618,318 A, CN 102 664 285 A, as well as JP 2011-138675 A and JP 2014-35998 A.

[0007] The invention is based on the object of creating an improved cell winding which offers a high level of protection against damage and, in particular, short circuits, even with tight bending radii.

[0008] The object underlying the invention is achieved by a cell coil having the features of claim 1. This has the advantage that the electrode strips are protected at their most vulnerable point, namely in the region of the bent sections connecting the electrode sections. Folding the electrode strips over one another results in the outer bent sections being easily damaged during assembly or production and, due to deformation, being able to come into electrical contact with one another. To avoid this, great care has been required during assembly and / or maintenance. With the cell coil according to the invention, the outer regions of the electrode strips are additionally protected by the separator strip.According to the invention, this is achieved in that the successive separator sections, i.e. the separator sections following one another in the longitudinal extension of the separator strip, alternately protrude with a protective section on one of their longitudinal sides at least beyond the respective electrode section of the other electrode strip. The protective section ensures that the separator strip laterally covers the bent sections of the other electrode strip in a plan view, so that the superimposed bent sections are reliably separated from one another by the separator strip. This reliably prevents electrical contact between the individual sections of the other electrode strip and between the other electrode strip and the one electrode strip, even in the event of subsequent force application, i.e. after assembly.The respective protective section extends at least beyond the respective electrode section of the other electrode strip, so that it reaches the area of ​​the bending section. Because the protective section is formed alternately along the long sides of the separator sections, it extends from the separator strip once on one long side and once on the other long side. This reliably protects the bending sections of the other electrode strip on both sides of the cell coil.

[0009] In particular, the protective sections protrude beyond the other electrode strips, so that the entire section of the other electrode strip protruding from the cell stack is securely protected by the protective sections. In particular, the respective protective section extends at least over the bending section of the other electrode strip, so that the adjacent bending sections are securely separated from one another by the separator section.

[0010] According to a preferred embodiment of the invention, the respective protective section extends partially into the folded section of the separator strip adjacent to the separator section. This results in an additional protective effect through the protective section, which improves electrical protection through lateral insulation and also mechanically hinders the deposition of particles between adjacent electrode strip sections and bending sections.

[0011] According to a preferred embodiment, the separator strip is designed as a flexible separator film. The separator film is, for example, applied, in particular glued, to one side of one of the electrode strips, so that it folds along with them, thereby producing / producing the cell coil described above.

[0012] According to an alternative embodiment, it is preferably provided that the separator strip is designed as a flexible separator tube that encloses the one electrode strip in cross-section. Thus, the separator strip or separator tube completely surrounds the one electrode strip on its circumference, so that the one electrode strip is electrically insulated on all sides. The additional protective sections are formed by the edge region of the separator tube.In particular, the separator tube is formed with a widened edge region and notches or lateral depressions are introduced into the respective side edge by a punching process, by means of which protective sections are formed between the depressions, which protrude laterally beyond one electrode strip so that they protrude laterally beyond the electrode sections of the other electrode strip in the cell winding, as already explained above.

[0013] Preferably, at least one of the electrode strips has a carrier strip provided with an electrode coating forming the electrode sections. This provides a cost-effective electrode strip that is easy to manufacture. Both electrode strips are preferably designed accordingly. By applying the electrode coating in sections, it is particularly possible to create separate electrode sections. While according to a first embodiment the electrode strip has a continuous electrode coating and the electrode sections are defined by the folding process, according to a further embodiment the electrode strips have separate electrode sections. This can be achieved by forming electrode coating sections spaced apart from one another.

[0014] Particularly preferably, the electrode sections of the at least one electrode strip, and optionally also the other of the electrode strips, are separated from one another by coating-free bending regions of the carrier strip. In particular, the coating is subsequently removed from the carrier strip in sections, for example by laser processing. This ensures particularly time-saving and cost-reduced production of separate electrode sections on the electrode strip. Because the bending regions of the carrier strip are coating-free, the flexibility of the carrier strip is greater in the bending regions, so that the folding process takes place with less effort. This also has the advantage that no electrode material can detach from the carrier material and lead to contamination of the electrolyte or short circuits.

[0015] The battery cell according to the invention with the features of claim 6 is characterized in that at least one cell coil is designed according to the invention. This results in the aforementioned advantages.

[0016] The energy storage device according to the invention with the features of claim 7 is characterized by at least one battery cell according to the invention. This also results in the advantages already mentioned.

[0017] The method according to the invention with the features of claim 8 is characterized in that the successive separator sections of the separator strip are alternately provided on one of their longitudinal sides before folding the electrode strips, which protective section projects laterally beyond the respective electrode section of the other electrode strip after the folding process, and in that the separator strip is designed as a flexible separator tube that encloses one of the electrode strips in cross-section. This results in the aforementioned advantages.

[0018] Further advantages and preferred features and combinations of features emerge in particular from the above description and from the claims. The invention will be explained in more detail below with reference to the drawings. Fig. 1 a cell coil according to the prior art in a perspective view, Fig. 2 an advantageous cell coil in an enlarged perspective view and Fig. 3 a separator strip of the cell coil in a plan view.

[0019] Fig. 1 shows a simplified perspective view of a battery cell 1 with a cell coil 2. The battery cell 1 has a housing 3 in which the cell coil 2 is arranged and held. The cell coil 2 has a first electrode strip 4 and a second electrode strip 5, wherein one of the electrode strips 4, 5 is designed as an anode strip and the other as a cathode strip. The electrode strips 4, 5 are folded together to form the cell stack 2. For this purpose, free ends of the electrode discs 4, 5 are placed one above the other in such a way that the electrode strips 4, 5 are aligned perpendicularly to one another, viewed in their longitudinal extent. The electrode strips are then alternately folded over one another so that the Fig. 1 results. The cell coil 2 is then placed in the housing 3 of the battery cell 1 and electronically contacted. For this purpose, the cell coil 2 has electrically conductive connection contacts 6, 7, which are electrically connected, for example, to bus bars of the respective electrode strips 4, 5. In this respect, the cell coil 2 shown corresponds to a conventional cell coil from the prior art. To prevent an electrical short circuit between the electrode strips 4, 5, the electrode strip 4 is assigned an electrically insulating separator strip 8, which extends along the electrode strip 4. According to the present exemplary embodiment, the separator strip 8 is formed by a separator tube 9, which, viewed in cross-section, completely encloses or houses the electrode strip 4, so that the electrode strip 4 is completely electrically insulated from the electrode strip 5. As Fig. 2, the separator tube 9 has a through opening 19 in which the electrode strip 4 extends.

[0020] As from Fig. As can be seen in Figure 1, the electrode strips 4 and 5 are divided into flat electrode sections 10 and 11, respectively, resting on one another, and into bent sections 12 and 13, respectively, connecting the electrode sections 10 and 11. The electrode strips 4 and 5 are folded over one another along the bent sections 12 and 13, respectively, so that the electrode sections rest on one another.

[0021] How Fig. 1, the bent sections 12 and 13 are located at the edge of the cell coil 2 and protrude from the other electrode strips 5, 4. As a result, they are relatively unprotected on the cell coil 2, so that assembly must be carried out with appropriate care.

[0022] Fig. 2 shows an advantageous further development of the cell coil 2, which offers additional protection of the cell coil 2, in particular of the electrode strips 4, 5, wherein the additional protection can be implemented simply and cost-effectively.

[0023] In the present case, the separator strip 8 or the separator hose 9 has a plurality of protective sections 14 which protrude laterally from the separator strip 8.

[0024] Fig. 3 shows a plan view of the unfolded separator strip 8 as it appears before the folding process.

[0025] In dashed lines is Fig. 3 also shows the electrode strip 4 located in the separator tube 9. As already mentioned, the electrode strip 4 has electrode sections 10 that are separated from one another by intermediate bent sections 13. In the present case, the electrode strip 4 has an electrode coating 15 that extends over a carrier strip 16 of the electrode strip 4. In the area of ​​the bent sections 13, the coating 15 is interrupted, so that the flexibility of the carrier strip 16 is available in the respective bent section 13 and is not reduced by the electrode coating 15. This ensures easy folding of the electrode strip 4.

[0026] Correlating with the bending sections 13, the separator strip 8 has folding sections 17, along which the separator strip 8 is folded when the electrode strip 4 is folded. Thus, the separator strip 8 is divided into folding sections 17 and separator sections 18, wherein the separator sections are each located between two superimposed electrode sections of the electrode strips 4, 5 in the cell coil 2 in order to electrically insulate them from one another.

[0027] Along its longitudinal extent, the protective sections 14 are formed alternately in the direction of the successive separator sections 18, once on one longitudinal side and once on the other longitudinal side of the separator strip 8.

[0028] This results in, as in Fig. 2 shows that each bending section 12 of the electrode strip 5 is separated from a protective section 14 by the adjacent bending section 12, so that collision of the bending sections 13 is prevented. Because the protective sections 14 also extend beyond the respective separator section 18 in some areas into the respective bending section 17, in particular beyond a center line of the respective bending section, as in Fig. As shown in Figure 3, the accumulation of particles in the area of ​​the bending sections 12 is further reduced. In particular, the special shape of the protective sections 14 encloses particles.

[0029] While according to the present embodiment the separator strip 8 is formed by the separator tube 9, according to a further embodiment it is provided that the separator strip 8 is designed as a separator film which is applied, in particular glued, to one side of the electrode strip 4. List of reference symbols 1 battery cell 2 cell coils / cell stacks 3 housings 4 electrode strips 5 electrode strips 6 connection contact 7 Connection contact 8 separator strips 9 Separator hose 10 Electrode section 11 Electrode section 12 Bending section 13 Bending section 14 Protection Section 15 Electrode coating 16 carrier strips 17 Bending section / folding section 18 Separator section 19 Opening

Claims

[1] Cell winding (2) for a lithium-ion battery cell (1), comprising an anode strip and a cathode strip as electrode strips (4, 5), and comprising a separator strip (8) arranged between the electrode strips (4, 5), wherein the electrode strips (4, 5) are aligned perpendicular to each other in their longitudinal extent and are alternately folded over one another, wherein the separator strip (8) is carried along with one of the electrode strips (4, 5) and has several separator sections (18) located between the overlapping electrode sections (10, 11) of the electrode strips (4, 5), which are connected to each other by folding sections (17), and wherein the separator strip (8) is designed as a flexible separator tube (9) which encloses one of the electrode strips (4, 5) in cross-section, characterized by, that the successive separator sections (18) of the separator strip (8) alternately project on one of their longitudinal sides with a protective section (14) at least beyond the respective electrode section (10,11) of the other electrode strip (4,5). [2] Cell wrap (2) according to claim 1, characterized by , that the protective sections (14) extend beyond the entire other electrode strips (10,11). [3] Cell wrap (2) according to any one of the preceding claims, characterized by , that the respective protective section (14) extends in some areas into the folding section (17) which adjoins the separator section (18). [4] Cell wrap (2) according to any one of the preceding claims, characterized by , that at least one of the electrode strips (4,5) has a carrier strip (16) which is provided with an electrode coating (15) forming the electrode sections (10,11). [5] Cell wrap (2) according to claim 4, characterized by , that the electrode sections (10,11) of the at least one electrode strip (4,5) are separated from each other by coating-free bending sections (12,13) ​​of the carrier strip (16). [6] Lithium-ion battery cell (1) for an energy storage device of a motor vehicle, in particular a traction battery, comprising a housing (3) in which at least one cell winding (2) is arranged and electrically contactable, characterized by , that at least one cell coil (2) is formed according to one of claims 1 to 5. [7] Energy storage device for a motor vehicle, in particular a traction battery, comprising at least one lithium-ion battery cell (1) according to claim 6. [8] Method for producing a cell winding (2), in particular according to one of claims 1 to 5, for a lithium-ion battery cell (1), comprising an anode strip and a cathode strip as electrode strips (4, 5) and a separator strip (8) carried with one of the electrode strips (4, 5), which are aligned at right angles to each other and are alternately folded over one another, such that the separator strip (8) forms several separator sections (18) located between the overlapping electrode sections (10, 11) of the electrode strips (4, 5), which are connected to each other by folding sections (17), and wherein the separator strip (8) is designed as a flexible separator tube (9) which encloses one of the electrode strips (4, 5) in cross-section, characterized by, that the successive separator sections (18) of the separator strip (8) are alternately provided on one of their longitudinal sides with a protective section (14) projecting at least beyond the respective electrode section (10,11).

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