Lithium-stuffed garnet thin films and pellets having an oxyfluorinated and/or fluorinated surface and methods of making and using the thin films and pellets

1. A process for making a sintered lithium-stuffed garnet thin film or pellet, comprising

(1) providing a solution comprising a fluoride salt and a solvent;

(2) providing a sintered lithium-stuffed garnet thin film or pellet;

(3) immersing at least one surface of the sintered lithium-stuffed garnet thin film or pellet in the solution at a temperature between, or equal to, 0° C. and 60° C.; and

(4) removing the at least one surface of the sintered lithium-stuffed garnet thin film from the solution.

2. The process of claim 1 , wherein fluoride salt is selected from the group consisting of LiPF 6 , lithium bis(perfluoroethanesulfonyl)imide (LIBETI), bis(trifluoromethane)sulfonimide lithium salt (LiTFSI), LiBF 4 , LiAsF 6 , lithium bis(fluorosulfonyl)imide (LiFSI), and combinations thereof.

3. The process of claim 1 , wherein the concentration of fluoride salt is about 0.5 M to about 1.5 M.

4. The process of claim 1 , wherein the solvent is selected from the group consisting of ethylene carbonate (EC), diethylene carbonate, dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), propylmethyl carbonate, nitroethyl carbonate, propylene carbonate (PC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), 2,5-dioxahexanedioic acid dimethyl ester, tetrahydrofuran (THF), γ-butyrolactone (GBL), fluoroethylene carbonate (FEC), fluoromethyl ethylene carbonate (FMEC), trifluoroethyl methyl carbonate (F-EMC), fluorinated 3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane (F-EPE), fluorinated cyclic carbonate (F-AEC), dioxolane, prop-1-ene-1,3-sultone (PES), sulfolane, acetonitrile (ACN), succinonitrile (SCN), pimelonitrile, suberonitrile, propionitrile, propanedinitrile, glutaronitrile (GLN), adiponitrile (ADN), hexanedinitrile, pentanedinitrile, acetophenone, isophorone, benzonitrile, ethyl propionate, methyl propionate, methylene methanedisulfonate, dimethyl sulfate, dimethyl sulfoxide (DMSO), ethyl acetate, methyl butyrate, dimethyl ether (DME), diethyl ether, dioxolane, gamma butyl-lactone, methyl benzoate, 2-methyl-5-oxooxolane-2-carbonitrile, and combinations thereof.

5. The process of claim 4 , wherein the solvent is selected from the group consisting of succinonitrile (SCN), glutaronitile (GLN), sulfolane, ethylene carbonate (EC), ethyl-methyl carbonate (EMC), and combinations thereof.

6. The process of claim 5 , wherein the solvent has a water content less than 200 ppm, or less than 150 ppm, or less than 100 ppm, or less than 60 ppm, or less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 20 ppm, or less than 10 ppm.

7. The process of claim 1 , wherein the lithium-stuffed garnet thin film or pellet, prior to step 3, is characterized by the chemical formula Li A La B Al C M″ D Zr E O F , wherein 5<A<8, 1.5<B<4, 0.1<C<2, 0≤D<2, 1<E<3, 10<F<13, and M″ is selected from the group consisting of Mo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, and Rb.

8. The process of claim 1 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet, after step 4, has a fluorinated surface.

9. The process of claim 8 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet, after step 4, has fluorine or fluoride present at a depth of penetration ranging from about 0.5 μm to about 1.5 μm.

10. The process of claim 8 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet, after step 4, comprises fluorine bonded to one or more elements in the lithium-stuffed garnet.

11. The process of claim 1 , wherein the at least one surface is free or substantially free of a contaminant after step 3.

12. The process of claim 11 , wherein the contaminant is Li 2 CO 3 .

13. A sintered lithium-stuffed garnet thin film or pellet comprising:

a top surface and bottom surface and a bulk therebetween,

wherein the top surface or bottom surface, or both, comprise fluorine;

wherein the fluorine is incorporated into, or bonded to, the lithium-stuffed garnet.

14. The sintered lithium-stuffed garnet thin film or pellet of claim 13 , wherein the lithium-stuffed garnet thin film or pellet bulk is characterized by the chemical formula Li A La B Al C M″ D Zr E O F , wherein 5<A<8, 1.5<B<4, 0.1<C<2, 0≤D<2, 1<E<3, 10<F<13, and M″ is selected from the group consisting of Mo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, and Rb.

15. The sintered lithium-stuffed garnet thin film or pellet of claim 13 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet has a fluorinated surface.

16. The sintered lithium-stuffed garnet thin film or pellet of claim 15 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet has fluorine or fluoride present at a depth of penetration ranging from about 0.5 μm to about 1.5 μm.

17. The sintered lithium-stuffed garnet thin film or pellet of claim 16 , wherein the at least one surface of the lithium-stuffed garnet thin film or pellet comprises fluorine bonded to one or more elements in the lithium-stuffed garnet.

18. The sintered lithium-stuffed garnet thin film or pellet of claim 14 , wherein the sintered lithium-stuffed garnet is a thin film.

19. The sintered thin film lithium-stuffed garnet of claim 13 , wherein the top surface or bottom surface, or both, remain free or substantially free of a contaminant after exposure to ambient conditions for 1 day to 365 days.

20. The sintered thin film lithium-stuffed garnet of claim 19 , wherein the contaminant is selected from the group consisting of hydroxides, peroxides, oxides, carbonates, and combination thereof.

21. The sintered thin film lithium-stuffed garnet of claim 20 , wherein the contaminant is Li 2 CO 3 .