Solid composite electrolyte membrane and method of making
A solid composite electrolyte membrane for use in a lithium battery is provided which exhibits a conductivity ranging from about 10 −4 S cm −1 to about 10 −3 S cm −1 at ambient temperature. The membrane is formed by providing a glass or glass-ceramic powder formed from a mixture of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate. The powder is mixed with a conditioning agent and at least one solvent, followed by the addition of a binder and one or more plasticizers. The resulting slurry is cast into a tape which is then subjected to a binder burn-off and sintering process to form the membrane. The resulting membrane may be a glass-ceramic composite having a porosity ranging from 0 to 50%, or the membrane may be further infiltrated with a polymer to form a water-impermeable polymeric-ceramic composite membrane.
1. A method of forming a solid composite electrolyte membrane for use in a lithium battery comprising:
providing a glass or glass-ceramic powder formed from a mixture of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate;
mixing said powder with a conditioning agent and at least one solvent to form a slurry;
adding a binder and at least one plasticizer containing organic components to said slurry;
casting said slurry into a tape; and
heating said tape to burn off said binder and sintering said tape to form said membrane.
2. The method of claim 1 wherein said tape is heated at a temperature from about 25° C. to 400° C. to burn off said organic components.
3. The method of claim 1 wherein said tape is sintered at a temperature of from 400 to 1200° C.
4. The method of claim 1 wherein said membrane has a porosity of from about 0% to about 50%.
5. The method of claim 1 wherein said membrane is porous and said method includes infiltrating said porous membrane with a polymer.
6. The method of claim 5 wherein said polymer is selected from polyethylene and polytetrafluoroethylene.
7. The method of claim 1 wherein said powder comprises from about 2 to about 7 wt % lithium oxide.
8. The method of claim 1 wherein said powder comprises from about 7 to about 12 wt % alumina.
9. The method of claim 1 wherein said powder comprises from about 25 to about 45 wt % titanium dioxide.
10. The method of claim 1 wherein said powder comprises from about 30 to about 70 wt % diphosphorous pentoxide.
11. The method of claim 1 wherein said glass-ceramic powder has a particle size of from about 1 to about 75 μm.
12. The method of claim 1 wherein said glass-ceramic powder has a particle size of from about 1 to 45 μm.
13. The method of claim 1 wherein said conditioning agent comprises fish oil.
14. The method of claim 1 wherein said at least one solvent is selected from xylene, alcohol, or combinations thereof.
15. The method of claim 1 wherein said binder comprises poly(vinyl butyl).
16. The method of claim 1 wherein said at least one plasticizer is selected from butylbenzyl phthalate, poly(alkylene glycol), and combinations thereof.