Encapsulated sulfide glass solid electrolytes and solid-state laminate electrode assemblies
Nanofilm-encapsulated sulfide glass solid electrolyte structures and methods for making the encapsulated glass structures involve a lithium ion conducting sulfide glass sheet encapsulated on its opposing major surfaces by a continuous and conformal nanofilm made by atomic layer deposition (ALD). During manufacture, the reactive surfaces of the sulfide glass sheet are protected from deleterious reaction with ambient moisture, and the nanofilm can be configured to provide additional performance advantages, including enhanced mechanical strength and improved chemical resistance.
1. A nanofilm-encapsulated sulfide glass solid electrolyte structure, the structure comprising:
a dense, moisture sensitive lithium ion conducting sulfide glass solid electrolyte sheet having substantially uniform thickness in the range of 5 50 μm and Li ion conductivity of at least 10 −5 S/cm, the sulfide glass sheet having first and second major opposing surfaces and a peripheral edge surface; and
a continuous inorganic nanofilm that conforms to the sulfide glass surfaces and encapsulates, in direct contact, the first and second major opposing surfaces of the glass sheet and the peripheral edge surface of the glass sheet;
wherein the nanofilm has an asymmetric architecture, is pinhole free and protects the encapsulated glass surfaces against chemical degradation by ambient moisture during storage or battery cell manufacture.
2. The solid electrolyte structure of claim 1 , having an area specific resistance (ASR) that is less than 200 Ω-cm 2 at room temperature.
3. The solid electrolyte structure of claim 2 , wherein the nanofilm comprises a first nanolayer deposited onto the first major surface of the sulfide glass sheet and a second nanolayer deposited onto the second major surface of the sulfide glass sheet and further wherein the first and second nanolayer have a different material composition.
4. The solid electrolyte structure of claim 3 , wherein the controlled atmosphere has a dew point in the range selected from the group consisting of −20° C. to −90° C.; −40° C. to −90° C.; −60° C. to −90° C.
5. The solid electrolyte structure of claim 3 , wherein the controlled atmosphere has a dew point selected from the group consisting of about −20° C., about −40° C., about −60° C., about −70° C., about −80° C., and about −90° C.
6. The solid electrolyte structure of claim 4 , wherein the solid electrolyte structure is exposed to the controlled atmosphere for a duration selected from the group consisting of 10 seconds to 60 seconds, 60 seconds to 120 seconds, 120 seconds to 300 seconds, 300 seconds to 600 seconds, and 600 seconds to 1800 seconds.
7. The solid electrolyte structure of claim 2 , wherein the nanofilm increases the flexural strength of the sulfide glass sheet by at least 30% or at least about 100%.
8. The solid electrolyte structure of claim 1 , wherein the nanofilm enhances the oxidative stability of the sulfide glass sheet, and thereby enables the solid electrolyte structure to directly contact an intercalation cathode material in a battery cell without chemical degradation, wherein the electrochemical potential of the cathode material versus lithium metal is at least 3 Volts.
9. A method of making a nanofilm-encapsulated sulfide glass solid electrolyte structure, the method comprising:
(i) providing a substrate-less lithium ion conducting sulfide glass solid electrolyte sheet having a thickness in the range of 5 to 50 μm, and having first and second major opposing surfaces and a peripheral edge surface; and
(ii) depositing by atomic layer deposition (ALD) a continuous inorganic nanofilm that encapsulates the sulfide glass sheet first and second major surfaces and the peripheral edge surface;
wherein the nanofilm has an asymmetric architecture, is pinhole free and protects the encapsulated glass surfaces against chemical degradation by ambient moisture during storage or battery cell manufacture.
10. The method of claim 9 , wherein the nanofilm is deposited onto all glass sheet surfaces.
11. The method of claim 9 , wherein the thickness of the nanofilm is selected from the group consisting of 1 nm to 5 nm, 0.1 nm to 1 nm, and 5 nm to 10 nm.
12. The method of claim 9 , wherein the nanofilm comprises a first nanolayer deposited onto the first major surface of the sulfide glass sheet and a second nanolayer deposited onto the second major surface of the sulfide glass sheet; and further wherein the first and second nanolayer have a different material composition.
13. The method of claim 12 , wherein the first nanolayer is a metal nitride and the second nanolayer is a metal oxide.
14. The method of claim 13 wherein the metal nitride is silicon nitride.
15. The method of claim 13 , wherein the metal oxide is selected from the group consisting of aluminum oxide, zirconium oxide, niobium oxide, and hafnium oxide.
16. The method of claim 9 , wherein the ALD is plasma enhanced.
17. The method of claim 9 , wherein the sulfide glass solid electrolyte sheet is in the form of a web of glass, and the atomic layer deposition is spatial ALD.
18. The method of claim 9 , wherein a first nanolayer is deposited on the first major surface during a first deposition step, and a second nanolayer is deposited on the second major surface during a second deposition step.
19. The method of claim 9 , wherein the nanofilm has a thickness of at least 5 nanometers.
20. A solid-state laminate electrode assembly comprising a nanofilm-encapsulated sulfide glass solid electrolyte structure in accordance with claim 1 , and further comprising a lithium metal layer in direct contact with the nanofilm.