Separator with improved ease of handling
Robust separator, which has on a substrate and in the intermediate spaces of the substrate, which comprises fibres of an electrically nonconducting material, an electrically nonconductive coating of 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 , wherein polymer particles are also present in the ceramic coating in addition to the oxide particles of Al 2 O 3 , ZrO 2 and/or SiO 2 . These separators are particularly easy to handle, since they are mechanically very stable.
1. A separator which has, on a substrate and in voids of the substrate, which comprises fibers of an electrically nonconductive material, a porous electrically nonconductive ceramic 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 , wherein organic polymer particles are also dispersed in the ceramic coating in addition to the oxide particles of Al 2 O 3 , ZrO 2 and/or SiO 2 ,
wherein the organic polymer particles are particles of a polyolefin polymer or particles of a polyolefin copolymer.
2. The separator as claimed in claim 1 , wherein the polymer particles have a melting point of more than 100° C.
3. The separator as claimed in claim 1 , wherein, in the separator, a volume fraction of the oxide particles to the polymer particles is from 2:1 to 100:1.
4. The separator as claimed in claim 1 , wherein the polymer particles have a mean particle size which corresponds to from 0.1 to 30 times the mean particle size of the oxide particles.
5. The separator as claimed in claim 4 , wherein the polymer particles comprise particles having a mean particle size which is smaller than 0.5 times a thickness of the separator.
6. The separator as claimed in claim 1 , wherein the substrate is a nonwoven polymer fabric which comprises polymer fibers selected from the group consisting of polyacrylonitrile, polyamide, polyester and polyolefin fibers.
7. The separator as claimed in claim 1 , wherein the inorganic adhesive is at least one selected from the group consisting of oxides of the elements Al, Si and Zr.
8. The separator as claimed in claim 1 , wherein the ceramic coating comprises at least one polymer film on an internal surface of the ceramic coating and an external surface of the ceramic coating.
9. The separator as claimed in claim 8 , wherein the film has a thickness of from 10 nm to 5 μm.
10. The separator as claimed in claim 8 , wherein the film has an open pore foam structure.
11. A method for the production of a separator as claimed in claim 1 , wherein a substrate which comprises fibers of an electrically nonconductive material and voids between the fibers is provided with a ceramic coating, for which purpose a suspension is applied on and in the substrate and said suspension is solidified by heating at least once on or in the substrate, the suspension comprising a sol and at least two particle fractions suspended in the sol, the first fraction comprises at least one oxide particle selected from the group consisting of oxides of elements Al, Zr and Si and the second fraction of which comprises polymer particles.
12. The method as claimed in claim 11 , wherein the proportion by volume of the particles of the oxide particle fraction used to the particles of the polymer particle fraction used is from 2:1 to 100:1.
13. The method as claimed in claim 11 , wherein at least one oxide particle fraction whose particles have a mean particle size of from 0.1 to 10 μm is used.
14. The method as claimed in claim 11 , wherein a polymer particle fraction whose particle has a mean particle size which corresponds to from 0.1 to 30 times the mean particle size of the suspended oxide particles is used.
15. The method as claimed in claim 11 , wherein an adhesion promoter which is selected from organofunctional silanes is also added to the suspension prior to application to the substrate.
16. The method as claimed in claim 11 , wherein the substrate used is a nonwoven polymer fabric which comprises fibers selected the group consisting of from a polyacrylonitrile, polyester, polyamide and polyolefin.
17. The method as claimed in claim 11 , wherein the sol is obtained by hydrolyzing a precursor compound of at least one of the elements Al, Zr and Si with water or an acid diluted with water.
18. The method as claimed in claim 11 , wherein the suspension present on and in the substrate 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 coating is first treated with a solution of a polymer and the solvent is then removed.
20. A method for producing batteries comprising inserting a separator as claimed in claim 1 into the batteries.
21. A lithium battery comprising a separator as claimed in claim 1 .
22. A vehicle comprising a lithium battery as claimed in claim 21 .
23. The separator as claimed in claim 1 , wherein the polymer particles are homogeneously dispersed in the ceramic coating.
24. The separator as claimed in claim 1 , wherein the oxide particles, the inorganic adhesive and the polymer particles are a homogeneous mixture.
25. The separator as claimed in claim 1 , wherein the organic polymer particles are particles of at least one polymer selected from the group consisting of PVDF, PP and PE.
26. The separator as claimed in claim 1 , wherein the organic polymer particles and the oxide particles are homogeneously dispersed in the ceramic coating.
27. The separator as claimed in claim 1 , wherein the organic polymer particles are particles of a polyolefin polymer.
28. The separator as claimed in claim 1 , wherein the organic polymer particles are particles of a polyolefin copolymer and the oxide particles are particles of aluminum oxide.
29. The separator as claimed in claim 1 , wherein the oxide particles are particles of aluminum oxide.