Separator with improved ease of handling
View Patent ↗Robust separator which has, on a substrate and in the voids of the substrate, which comprises fibers of an electrically nonconductive material, an electrically nonconductive coating comprising oxide particles which are adhesively bonded to one another and to the substrate by an inorganic adhesive and comprise at least one oxide selected from Al 2 O 3 , ZrO 2 and SiO 2 , polymer particles also being present in the ceramic coating in addition to the oxide particles of Al 2 O 3 , ZrO 2 and/or SiO 2 . These separators have particularly good handling properties since they are mechanically very stable.
1. A separator, comprising:
a substrate comprising fibers of an electrically nonconductive material and voids, and
a ceramic porous electrically nonconductive coating on the substrate and in the voids of the substrate,
wherein
the ceramic porous electrically nonconductive coating comprises (a) oxide particles comprising at least one oxide selected from the group consisting of Al 2 O 3 , ZrO 2 and SiO 2 and (b) polymer particles,
the oxide particles are adhesively bonded to one another and to the substrate by an inorganic adhesive,
the polymer particles are dispersed throughout the ceramic porous electrically nonconductive coating, and
wherein the polymer particles have a melting point of more than 100° C.
2. The separator as claimed in claim 1 , wherein, in the separator, the volume fraction of the oxide particles to the polymer particles is from 2:1 to 100:1.
3. The separator as claimed in claim 1 , wherein the polymer particles have a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
4. The separator as claimed in claim 3 , which exclusively comprises polymer particles which have a mean particle size which is smaller than 0.5 times the thickness of the separator.
5. The separator as claimed in claim 1 , wherein the substrate is a nonwoven polymer fabric which comprises polymer fibers which are selected from fibers of polyacrylonitrile, polyamide, polyester and/or polyolefin.
6. The separator as claimed in claim 1 , wherein the inorganic adhesive is selected from oxides of the elements Al, Si and/or Zr.
7. The separator as claimed in claim 1 , wherein the ceramic porous electrically nonconductive coating comprises a film comprising one or more polymers.
8. The separator as claimed in claim 7 , wherein the film has a thickness of from 10 nm to 5 μm.
9. The separator as claimed in claim 7 , wherein the film has a foam-like structure.
10. The separator as claimed in claim 1 , which is obtained by applying the ceramic porous electrically nonconductive coating to the substrate.
11. A method for the production of a separator as claimed in claim 1 , comprising:
applying a suspension to the substrate, and
heating the suspension applied to the substrate to solidify the suspension,
wherein
the suspension comprises a sol and at least two particle fractions suspended in the sol,
a first particle fraction suspended in the sol comprises the oxide particles comprising at least one oxide selected from the group consisting of Al 2 O 3 , ZrO 2 and SiO 2 , and
a second particle fraction suspended in the sol comprises the polymer particles, the polymer particles having a melting point of more than 100° C.
12. The method as claimed in claim 11 , wherein the proportion by volume of the oxide particles to the polymer particles is from 2:1 to 100:1.
13. The method as claimed in claim 11 , wherein the oxide particles comprise a fraction having a mean particle size of from 0.1 to 10 μm.
14. The method as claimed in claim 11 , wherein the polymer particles comprise a fraction having a mean particle size which corresponds to from 0.1 to 30 times the mean particle size of the oxide particles.
15. The method as claimed in claim 11 , wherein the suspension further comprises an adhesion promoter selected from the group consisting of organofunctional silanes.
16. The method as claimed in claim 11 , wherein the substrate is a nonwoven polymer fabric which comprises fibers selected from a polyacrylonitrile, polyester, polyamide and/or polyolefin.
17. The method as claimed in claim 11 , wherein the sol is obtained by hydrolyzing a precursor compound of one of the elements Al, Zr or Si with water or an acid diluted with water.
18. The method as claimed in claim 11 , wherein the suspension is solidified by heating to 50 to 350° C.
19. The method as claimed in claim 11 , wherein, after solidification of the suspension, the resulting ceramic porous electrically nonconductive coating is then treated with a solution of a polymer in a solvent and then the solvent is removed.
20. A lithium battery, comprising the separator as claimed in claim 1 .
21. A vehicle, comprising the lithium battery as claimed in claim 20 .
22. The separator as claimed in claim 1 , wherein the polymer particles are particles of polymers and copolymers of polyvinylidene fluoride (PVDF).
23. The separator as claimed in claim 5 , wherein the volume fraction of the oxide particles to the polymer particles is from 2:1 to 100:1.
24. The separator as claimed in claim 23 , wherein the polymer particles have a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
25. The separator as claimed in claim 24 , which exclusively comprises polymer particles having a mean particle size which is smaller than 0.5 times the thickness of the separator.
26. The separator as claimed in claim 5 , wherein the polymer particles have a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
27. The separator as claimed in claim 26 , which exclusively comprises polymer particles having a mean particle size which is smaller than 0.5 times the thickness of the separator.
28. The separator as claimed in claim 2 , wherein the polymer particles have a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
29. The separator as claimed in claim 28 , which exclusively comprises polymer particles having a mean particle size which is smaller than 0.5 times the thickness of the separator.
30. The separator as claimed in claim 1 , wherein the ceramic porous electrically nonconductive coating has on its surface a film comprising one or more polymers.
31. The separator as claimed in claim 30 , wherein the film has a thickness of from 10 nm to 5 μm.
32. The separator as claimed in claim 30 , wherein the film has a foam-like structure.
33. The separator as claimed in claim 32 , wherein the film comprises PVDF or PVDF copolymers.
34. The separator as claimed in claim 31 , wherein the film has a foam-like structure.
35. The separator as claimed in claim 34 , wherein the film comprises PVDF or PVDF copolymers.
36. The separator as claimed in claim 9 , wherein the film comprises PVDF or PVDF copolymers.
37. The separator as claimed in claim 8 , wherein the film has a foam-like structure.
38. The separator as claimed in claim 37 , wherein the film comprises PVDF or PVDF copolymers.
39. The method as claimed in claim 12 , wherein the oxide particles comprise a fraction having a mean particle size of from 0.1 to 10 μm.
40. The method as claimed in claim 39 , wherein the polymer particles comprise a fraction having a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
41. The method as claimed in claim 12 , wherein the polymer particles comprise a fraction having a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
42. The method as claimed in claim 13 , wherein the polymer particles comprise a fraction having a mean particle size of from 0.1 to 30 times the mean particle size of the oxide particles.
43. The method as claimed in claim 19 , wherein a film having a foam-like structure is obtained by removing the solvent.
44. The method as claimed in claim 43 , wherein the solution of one or more polymers comprises PVDF or PVDF copolymers.
45. A separator obtained by the method according to claim 11 .
46. A method of preparing the substrate as claimed in claim 1 , comprising applying the ceramic porous electrically nonconductive coating to the substrate.
47. The separator as claimed in claim 1 , wherein the substrate comprises voids between the fibers.
48. The separator as claimed in claim 1 , further comprising at least one shut-down layer.
49. The separator as claimed in claim 1 , further comprising at least one shut-down layer, wherein the shut-down layer comprises at least one component selected from the group consisting of waxes, polymers, polymer blends and polymer mixtures.
50. The separator as claimed in claim 49 , wherein the at least one component has a melting point of less than or equal to 180° C.
51. The separator as claimed in claim 1 , further comprising a shut-down layer on only one side of the separator.
52. The separator as claimed in claim 1 , wherein the separator further comprises an inorganic, silicon-comprising network between the oxide particles of the ceramic porous electrically nonconductive coating, and wherein the network comprises silicon bound via oxygen atoms to the oxide particles of the coating and via an organic group to the substrate.
53. The separator as claimed in claim 7 , wherein the film covers at least one surface of the ceramic porous electrically nonconductive coating.
54. The separator as claimed in claim 53 , wherein the film has a thickness of from 10 nm to 5 μm.
55. The separator as claimed in claim 54 , wherein the film has a foam-like structure.
56. The separator as claimed in claim 53 , wherein the film has a foam-like structure.