Claims
- 1. A process for making a separator for an electrochemical device, comprising the steps of blending together a thermoplastic polymer, a tertiary plasticiser, and a filler which comprises a lithium compound which is substantially insoluble in the polymer, the blend comprising from 1 to 50 parts by weight of plasticizer and from 150 to 350 parts by weight of filler per hundred parts of polymer; forming the blend into a film; and stretching the film to render it porous.
- 2. A process as claimed in claim 1, wherein the film is stretched by at least 100%.
- 3. A process as claimed in claim 1, wherein the film is stretched by at 250%.
- 4. A process as claimed in claim 1, wherein the blend is formed into the film by extrusion.
- 5. A process as claimed in claim 1, further comprising the step of extracting the plasticizer from the film.
- 6. A process as claimed in claim 5, wherein the extraction step is performed after the stretching step.
- 7. A process as claimed in claim 1, further comprising the step of extracting the filler from the film.
- 8. A process as claimed in claim 1, wherein the thermoplastic polymer is a polyolefin.
- 9. A process as claimed in claim 1, wherein the thermoplastic polymer is polypropylene or polyethylene.
- 10. A process as claimed in claim 1, wherein the particle size of the filler is less than 8 micrometers.
- 11. A process as claimed in claim 1, wherein the filler comprises lithium carbonate, lithium phosphate, or lithium aluminate.
- 12. A process as claimed in claim 1, in which the film is applied to a body of reactive metal so as to protect it.
- 13. A process as claimed in claim 12, wherein the reactive metal comprises lithium metal.
- 14. A process as claimed in claim 12, in which the film is applied to the body of reactive metal so as to encapsulate it.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8517571 |
Jul 1985 |
GBX |
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Parent Case Info
This application is a division of application Ser. No. 884,131, filed July 10, 1986 now abandoned.
US Referenced Citations (14)
Foreign Referenced Citations (6)
Number |
Date |
Country |
0143562 |
Jun 1985 |
EPX |
0143566 |
Jun 1985 |
EPX |
0146246 |
Jun 1985 |
EPX |
WO8403177 |
Aug 1984 |
WOX |
0059285 |
Oct 1981 |
GBX |
0146245 |
Nov 1984 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
884131 |
Jul 1986 |
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