Method for Producing a Cathode for a Lithium-Ion Battery, and Lithium-Ion Battery

Abstract

A method for producing a cathode for a lithium-ion battery includes providing a cathode collector carrier film and applying a coating compound onto at least one main surface of the cathode collector carrier film. The coating compound contains a particulate auxiliary material. The coating compound is subsequently compressed to form a cathode film on the cathode collector carrier film. During the compression of the coating compound, the cathode collector carrier film is perforated. A lithium-ion battery is also described.

Claims

1-10. (canceled)

11. A method for producing a cathode for a lithium-ion battery, the method comprising: providing a cathode collector carrier foil; applying a coating compound comprising a particulate auxiliary material to at least one main face of the cathode collector carrier foil; and compressing the coating compound to form a cathode film on the cathode collector carrier foil, the cathode collector carrier foil being perforated by the particulate auxiliary material during the compression of the coating compound.

12. The method according to claim 11, wherein the particulate auxiliary material is selected from the group consisting of lithium ion conductors, SiO.sub.2, Al.sub.2O.sub.3, TiO.sub.2, B.sub.2O.sub.3, boehmite, synthetic diamond dust, and combinations thereof.

13. The method according to claim 11, wherein the particulate auxiliary material has a Mohs hardness in a range from 2 to 10.

14. The method according to claim 13, wherein the Mohs hardness is in a range from 2.75 to 10.

15. The method according to claim 11, wherein the coating compound comprises an adjuvant selected from the group consisting of synthetic graphite, natural graphite, carbon nanotubes, carbon black, carbon fibers, soft carbon, hard carbon, and combinations thereof.

16. The method according to claim 11, wherein the coating compound comprises a binder selected from the group consisting of styrene-butadiene rubber (SBR), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), polyamide (PA), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylate, carboxymethylcellulose (CMC), polyimide (PI), PTFE, and combinations thereof.

17. The method according to claim 11, wherein applying the coating compound to the cathode collector carrier foil comprises wet coating, dry coating, pressing, laminating, lining, extruding and/or spraying.

18. The method according to claim 11, wherein the coating compound comprises a cathode active material.

19. The method according to claim 11, further comprising applying an active-material coating compound to the cathode collector carrier foil.

20. The method according to claim 19, wherein the coating compound is applied to the cathode collector carrier foil temporally before the active-material coating compound is applied to the cathode collector carrier foil.

21. The method according to claim 20, wherein the coating compound is applied in a first layer to the cathode collector carrier foil; and the active-material coating compound is applied in a second layer over the first layer.

22. The method according to claim 21, wherein a ratio of the thickness of the first layer to the second layer is in a range from 1:2 to 1:100.

23. The method according to claim 22, wherein the ratio is in a range from 1:3 to 1:40.

24. The method according to claim 20, wherein the coating compound and the active-material coating compound are applied using a coating apparatus having at least two nozzles, the coating compound and the active-material coating compound being metered via different nozzles.

25. The method according to claim 19, wherein the coating compound and the active-material coating compound are applied simultaneously to the cathode collector carrier foil.

26. The method according to claim 25, further comprising: prior to application to the cathode collector carrier foil, mixing the coating compound with the active-material coating compound to form an overall compound; and applying the overall compound to the cathode collector carrier foil using a nozzle.

27. The method according to claim 11, wherein the particulate auxiliary material has at least one edge, one angle, one tip, one point and/or one projection.

28. The method according to claim 11, wherein the particulate auxiliary material comprises an agglomerate composed of multiple agglomerated particles.

29. The method according to claim 11, wherein a mean particle size D.sub.50 of the particulate auxiliary material is at least 0.5 times a thickness of the cathode collector carrier foil.

30. A lithium-ion battery comprising at least one cathode prepared by the method according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG. 1 shows schematically a sectional view of a cathode as known in the prior art;

[0063] FIG. 2 shows schematically a sectional view of a cathode as may be produced using a method of the disclosure;

[0064] FIG. 3 shows a block diagram of the method of the disclosure for producing the cathode from FIG. 2; and

[0065] FIG. 4 shows, schematically, a sectional view of an intermediate stage in the production of the cathode from FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a schematic sectional view of a cathode 10, not according to the disclosure, of a lithium-ion battery of the kind known in the prior art.

[0067] The cathode 10 comprises a cathode collector carrier foil 12, which also serves as a current diverter of the cathode 10.

[0068] The cathode collector carrier foil 12 is more particularly an aluminum foil.

[0069] On a first main face 14 and also on a second main face 16, opposite the first main face 14, of the cathode collector carrier foil 12, a cathode active material 18 is applied in the form of a cathode film 19.

[0070] The cathode active material 18 may be any material commonplace in the prior art that is capable of reversibly accepting and delivering lithium ions.

[0071] As can be seen in FIG. 1, the cathode collector carrier foil 12 has no apertures at all. Accordingly, the cathode collector carrier foil 12 is impervious to an electrolyte, and so the wetting of the cathode 10 with the electrolyte in a lithium-ion battery takes place only slowly and/or incompletely.

[0072] FIG. 2 represents a cathode 10 of the kind obtainable by a method of this disclosure for producing a cathode.

[0073] For components which are substantially analogous to the prior art, identical reference signs are used, and reference is made to the observations above; below, consequently, only differing features and components are explained in more detail.

[0074] The cathode 10 represented in FIG. 2 has a cathode collector carrier foil 12 with multiple apertures 20, which each extend through the entire thickness of the cathode collector carrier foil 12, hence from the first main face 14 to the second main face 16.

[0075] There may of course also be a number of apertures 20 which differ from the embodiment shown in FIG. 2, provided at least one aperture 20 is present for the passage of electrolyte through the cathode collector carrier foil 12.

[0076] Additionally, the cathode 10 has a particulate auxiliary material 22 which is disposed at least partially in the apertures 20.

[0077] The particulate auxiliary material 22 is selected from the group consisting of lithium ion conductors, SiO.sub.2, Al.sub.2O.sub.3, TiO.sub.2, B.sub.2O.sub.3, boehmite, synthetic diamond dust, and combinations thereof, and has a mean particle size D.sub.50 in the order of magnitude of the thickness of the cathode collector carrier foil 12, and also has a Mohs hardness in the range from 2 to 10, more particularly a Mohs hardness in the range from greater than 2.75 to 10for example, 3 to 10.

[0078] The apertures 20 enable passage of electrolyte from the first main face 14 in the direction of the second main face 16 and also from the second main face 16 in the direction of the first main face 14, and so the cathode as represented in FIG. 2 can be wetted more rapidly and more uniformly with electrolyte than is the case with the cathode 10 known from the prior art, as represented in FIG. 1.

[0079] Explained in more detail below is the method of the disclosure for producing the cathode 10 as is shown in FIG. 2.

[0080] First of all, the cathode collector carrier foil 12 is provided (cf. step S1 in FIG. 3), with the cathode collector carrier foil 12 corresponding to that from FIG. 1, in other words, as yet having none of the apertures 20 (cf. FIG. 2).

[0081] Subsequently, a coating compound is applied to the first main face 14 of the cathode collector carrier foil 12 (cf. step S2 in FIG. 3 and also FIG. 4).

[0082] As shown more closely in FIG. 4, the application of the coating compound in the embodiment represented takes place via the application of an overall compound 24 to the first main face 14, with the overall compound 24 comprising the coating compound and also an active-material coating compound.

[0083] The coating compound comprises the particulate auxiliary material 22 and also a binder, which is not shown in any more detail. The binder is selected from the group consisting of styrene-butadiene rubber (SBR), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), polyamide (PA), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylate, carboxymethylcellulose (CMC), polyimide (PI), PTFE, and combinations thereof.

[0084] The coating compound may further comprise an adjuvant which is selected from the group consisting of synthetic graphite, natural graphite, carbon nanotubes, carbon black, conducting carbon black for example, carbon fibers, soft carbon, hard carbon, and combinations thereof. The adjuvant may increase the conductivity of the coating compound and also improve its processing qualities and/or application qualities.

[0085] The active-material coating compound comprises the cathode active material 18 and also an active material binder or electrode binder, this binder not being shown in any more detail.

[0086] Following application of the overall compound 24, the particulate auxiliary material 22 settles owing to gravity, and so it is directly adjacent to the cathode collector carrier foil 12, as shown in FIG. 4.

[0087] In principle, the coating compound with the particulate auxiliary material 22, and the active-material coating compound, may also be applied individually in succession on the cathode collector carrier foil 12.

[0088] The coating compound, the active-material coating compound and/or the overall compound 24 may be applied to the cathode collector carrier foil 12 by wet coating, dry coating, pressing, laminating, lining, extruding and/or spraying.

[0089] Applied on the second main face 16, as shown in FIG. 4, is only an active-material coating compound. In principle, of course, it would be possible to use an overall compound 24 or a coating compound on the second main face 16 as well.

[0090] Starting from the intermediate stage shown in FIG. 4, the coating compound, more precisely the overall compound 24 in the embodiment shown, is compressed to form the cathode film 19 (cf. FIG. 2), by calendering (cf. step S3 in FIG. 3), for example.

[0091] In this case, a force F is exerted on the overall compound 24, as indicated by an arrow in FIG. 4, thereby pressing the particulate auxiliary material 22 into the cathode collector carrier foil 12 and perforating this foil, owing to the higher hardness of the particulate auxiliary material 22 in comparison to the cathode collector carrier foil 12, in order to produce the apertures 20.

[0092] The method of this disclosure thus makes it possible to generate the apertures 20, which can be used for improving the wetting, in situ during the production of the cathode 10.