Thin film battery and electrolyte therefor
A solid amorphous electrolyte composition for a thin-film battery. The electrolyte composition includes a lithium phosphorus oxynitride material containing an aluminum ion dopant wherein the atomic ratio of aluminum ion to phosphorus ion (Al/P) in the electrolyte ranges greater than zero up to about 0.5. The composition is represented by the formula: Li t P x Al y O u N v S w , where 5x+3y=5, 2u+3v+2w=5+t, t ranges from about 2.9 to about 3.3, x ranges from about 0.94 to about 0.85, y ranges from about 0.094 to about 0.26, u ranges from about 3.2 to about 3.8, v ranges from about 0.13 to about 0.46, and w ranges from zero to about 0.2. Thin film batteries containing such electrolyte films have less tendency to fail prematurely.
1. A solid amorphous electrolyte composition for a thin-film battery comprising a lithium phosphorus oxynitride material containing an aluminum ion dopant, wherein the atomic ratio of aluminum ion to phosphorus ion (Al/P) in the electrolyte ranges from greater than zero up to about 0.5, and wherein the composition is represented by the formula:
Li t P x Al y O u N v S w ,
where 5x+3y=5, 2u+3v+2w=5+t, t ranges from about 2.9 to about 3.3, x ranges from about 0.94 to about 0.85, y ranges from about 0.094 to about 0.26, u ranges from about 3.2 to about 3.8, v ranges from about 0.13 to about 0.46, and w ranges from zero to about 0.2.
2. The composition of claim 1 wherein the Al/P ratio ranges from about 0.10 to about 0.3.
3. The composition of claim 1 comprising from about 35 to about 50 atomic percent lithium ion.
4. The composition of claim 1 comprising from about 10 to about 12 atomic percent phosphorus ion.
5. The composition of claim 1 comprising from about 35 to about 50 atomic percent oxygen ion.
6. The composition of claim 1 wherein w is greater than zero.
7. A thin-film battery comprising the solid electrolyte of claim 1 .
8. The thin-film battery of claim 7 comprising a cathode selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , and V 2 O 5 .
9. The thin-film battery of claim 8 including a cathode current collector comprising indium tin oxide.
10. A method for making a solid electrolyte for a thin-film battery comprising the steps of:
providing a lithium orthophosphate (Li 3 PO 4 ) composition;
providing an aluminum ion source, and, optionally, a sulfide ion source;
combining the lithium orthophosphate composition, aluminum ion source, and, optional sulfide ion source to yield a sputtering target;
sputtering the target in a gas atmosphere selected from nitrogen gas, argon gas, and mixtures of nitrogen and argon gases to provide an electrolyte film having a composition represented by the formula:
Li t P x Al y O u N v S w ,
where 5x+3y=5, 2u+3v+2w=5+t, t ranges from about 2.9 to about 3.3, x ranges from about 0.94 to about 0.85, y ranges from about 0.094 to about 0.26, u ranges from about 3.2 to about 3.8, v ranges from about 0.13 to about 0.46, and w ranges from zero to about 0.2, and wherein the ratio of aluminum ion to phosphorus ion (Al/P) ranges from greater than zero up to about 0.5.
11. The method of claim 10 wherein the Al/P ratio ranges from about 0.10 to about 0.3.
12. The method of claim 10 wherein the sputtering is conducted in pure nitrogen gas.
13. The method of claim 10 wherein the sputtering is conducted in pure argon gas.
14. The method of claim 10 wherein the sputtering is conducted in a mixture of nitrogen gas and argon gas.
15. The method of claim 10 wherein the sputtering is conducted over a thin-film battery cathode material selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , and V 2 O 5 .
16. The method of claim 10 wherein the aluminum ion source is selected from the group consisting of aluminum metal, aluminum nitride, and aluminum oxide.
17. A thin-film battery containing a solid electrolyte made by the method of claim 10 .
18. The thin-film battery of claim 17 including a cathode current collector comprising indium tin oxide.
19. A method for making an aluminum-doped solid lithium phosphorus oxynitride electrolyte for a thin-film battery comprising the steps of:
providing a lithium orthophosphate (Li 3 PO 4 ) composition and an aluminum ion source as a sputtering target;
sputtering the target in an atmosphere containing nitrogen gas and hydrogen sulfide gas wherein the mixture of nitrogen gas and hydrogen sulfide gas in the atmosphere is represented by the following:
(1 −z )N 2 +z H 2 S,
where z is greater than 0 and less than 1 to provide an electrolyte film having a composition represented by the formula:
Li t P x Al y O u N v S w ,
where 5x+3y=5, 2u+3v+2w=5+t, t ranges from about 2.9 to about 3.3, x ranges from about 0.94 to about 0.85, y ranges from about 0.094 to about 0.26, u ranges from about 3.2 to about 3.8, v ranges from about 0.13 to about 0.46, and w ranges from zero to about 0.2.
20. The method of claim 19 wherein the sputtering is conducted in a mixture of nitrogen gas and argon gas.
21. The method of claim 19 wherein the sputtering is conducted over a thin-film battery cathode material selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , and V 2 O 5 .
22. The method of claim 19 wherein the aluminum ion source is selected from the group consisting of aluminum metal, aluminum nitride, and aluminum oxide.
23. A thin-film battery containing a solid electrolyte made by the method of claim 19 .
24. The thin-film battery of claim 23 including a cathode current collector comprising indium tin oxide.