Stabilized solid garnet electrolyte and methods thereof
An air stable solid garnet composition, comprising: a bulk composition and a surface protonated composition on at least a portion of the bulk composition as defined herein, and the protonated surface composition is present on at least a portion of the exterior surface of the bulk composition at a thickness of from 0.1 to 10,000 nm. Also disclosed is a composite electrolyte structure, and methods of making and using the composition and the composite electrolyte structure.
1. A solid garnet electrolyte membrane, comprising:
a bulk composition comprising a Li (7-z) La (3-y) Ga y Zr (2-z) Nb z O 12 lithium garnet; and
a surface composition comprising a Li (7-z-x) H x La (3-y) Ga y Zr (2-z) Nb z O 12 protonated garnet on at least a portion of the exterior surface of the lithium garnet, wherein the surface protonated portion of the garnet is compositionally stable in air and insensitive to carbon dioxide, and wherein x is from 0.1 to 7, y is from 0.1 to 0.3, and z is from 0.1 to 0.3.
2. The solid garnet electrolyte membrane of claim 1 wherein
the lithium garnet is Li 6.75 La 2.9 Ga 0.1 Nb 0.25 Zr 1.75 O 12 and
the protonated garnet is Li (6.75-x) H x La 2.9 Ga 0.1 Nb 0.25 Zr 1.75 O 12 ,
where x is from 0.1 to 6.75.
3. The solid garnet electrolyte membrane of claim 1 wherein the protonated garnet on at least a portion of the exterior surface of the lithium garnet comprises the entire exterior surface of the lithium garnet.
4. The solid garnet electrolyte membrane of claim 1 wherein the protonated garnet on at least a portion of the exterior surface of the lithium garnet comprises a layer having a thickness of from 0.1 to 100 nm.
5. The solid garnet electrolyte membrane of claim 1 wherein the surface composition has a lithium concentration of from 0.1 to 46 mol %.
6. The solid garnet electrolyte membrane of claim 1 wherein the surface composition is substantially free of an electrically insulating Li surface species.
7. The solid garnet electrolyte membrane of claim 1 wherein the surface composition comprises a surface free of at least one of LiOH, Li 2 CO 3 , or a combination thereof.
8. A composite electrolyte structure, comprising:
a protected anode structure comprising:
a first layer comprising a ceramic electrolyte comprising the solid garnet electrolyte membrane of claim 1 ;
a second layer comprising a source of lithium metal, wherein the first layer and the second layer are in physical contact; and
a cathode.
9. The composite electrolyte structure of claim 8 further comprising an aqueous catholyte situated between and in contact with the protected anode structure and the cathode.
10. The composite electrolyte structure of claim 8 wherein the cathode is a lithium cobalt oxide compound.
11. A method of making the solid garnet composition of claim 1 , comprising:
contacting an air sensitive lithium containing garnet with a protic acid to form the solid garnet composition having a protonated garnet surface composition.
12. The method of claim 11 wherein the protic acid is selected from at least one of: a mineral acid an organic acid or a combination thereof.
13. The method of claim 11 further comprising contacting the air stable and carbon dioxide insensitive solid garnet composition having the protonated garnet surface with a source of lithium ions to regenerate the air sensitive lithium containing solid garnet.
14. The method of claim 13 wherein the contacting with a source of lithium ions is accomplished in a sealed cell structure.
15. The method of claim 13 wherein the source of lithium ions is lithium metal.
16. The solid garnet electrolyte membrane of claim 1 , wherein the membrane is sintered.
17. An energy storage device comprising the solid garnet electrolyte membrane of claim 1 .
18. An energy storage device comprising the composite electrolyte structure of claim 8 .