Composite separator and electrolyte for solid state batteries
Separator and electrolyte composites include a porous self-supporting separator film between or adjacent one or two electrolyte films. The electrolyte films may contain a glyme or mixture of glymes, LiX salt and complexing agent, such as PEO. The porous self-supporting separator film may be used dry or wetted with a liquid electrolyte composition. Solid state batteries include the described separator and electrolyte composites in combination with an anode and a cathode.
1. A composite separator and electrolyte for an electrochemical cell comprising:
an insulating porous self-supporting separator film comprising pore sizes that range from 0.015 micrometers to 1 micrometer,
the insulating porous self-supporting film having a first major surface and a second major surface; and
at least one electrolyte film contacting the first major surface of the porous self-supporting film, the at least one electrolyte film comprising:
from about 34 to about 60 weight percent of a glyme or mixture of glymes and a lithium salt in an amount of from about 40 to about 66 weight percent, each weight percent based on the total weight of the glyme and lithium salt combined, and
a polymeric complexing agent present in an amount of from about 10 to about 30 percent by weight, based on the total weight of the electrolyte composition.
2. The composite separator and electrolyte according to claim 1 wherein the porous self-supporting separator film is saturated with a liquid electrolyte composition.
3. The composite separator and electrolyte according to claim 1 wherein the lithium salt is lithium bis(trifluoromethylsulfonyl) imide, lithium bis(pentafluoroethylsulfonyl) imide, lithium tris(trifluorosulfonyl) methide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate or combinations of any of them.
4. The composite separator and electrolyte according to claim 1 wherein the glyme is tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, poly(ethylene glycol dimethyl ether) having a molecular weight of 200 g/mol to 2000 g/mol, poly(ethylene glycol) having a molecular weight of 200 g/mol to 2000 g/mol, polyglycol methyl ether having a molecular weight of 200 g/mol to 2000 g/mol, ethylene glycol dibutyl ether, or combinations of any of them.
5. The composite separator and electrolyte according to claim 1 wherein the polymeric complexing agent is polyethylene oxide.
6. The composite separator and electrolyte according to claim 1 further comprising inorganic particles.
7. The composite separator and electrolyte according to claim 1 wherein the lithium salt is present in an amount of from about 46 to about 66 percent by weight,-based on the total weight of the glyme and lithium salt combined.
8. The composite separator and electrolyte according to claim 1 wherein the glyme is present in an amount of from about 34 to about 54 percent by weight, based on the total weight of the glyme and lithium salt combined.
9. The composite separator and electrolyte according to claim 1 wherein the polymeric complexing agent is polyethylene oxide and is present in an amount of from about 10 to about 15 percent by weight, based on the total weight of the electrolyte composition.
10. The composite separator and electrolyte according to claim 1 wherein the at least one electrolyte film is non-aqueous.
11. The composite separator and electrolyte according to claim 1 wherein the porous self-supporting separator film is dry.
12. The composite separator and electrolyte according to claim 1 wherein the lithium salt is lithium bis(trifluoromethylsulfonyl) imide.
13. The composite separator and electrolyte according to claim 1 wherein the glyme is tetraethylene glycol dimethyl ether.
14. The composite separator and electrolyte according to claim 1 wherein the polyethylene oxide has a molecular weight of from 100,000 Da to 8,000,000 Da.
15. The composite separator and electrolyte of claim 1 wherein the electrolyte has a means weight loss using thermogravimetric analysis measurement of less than 10% at temperatures up to 200° C.
16. The composite separator and electrolyte of claim 1 wherein the insulating porous self-supporting separator film comprises one or more of:
cellulose,
polypropylene,
polyethylene,
polypropylene-polyethylene-polypropylene tri-layer, or
ceramic material comprising aluminum oxide, zirconium oxide, silicon oxide, or a combination thereof.