Protective layers comprising metals for electrochemical cells
Articles and methods involving protected electrode structures are generally provided. In some embodiments, a protected electrode structure includes an electrode comprising an alkali metal and a protective structure directly adjacent the electrode. In some embodiments, the protective structure comprises elemental carbon and intercalated ions. In some embodiments, the protective structure is a composite protective structure. The composite structure may comprise an alloy comprising an alkali metal, an oxide of an alkali metal, and/or a fluoride salt of an alkali metal.
1. A protected electrode structure, comprising:
an electrode comprising an alkali metal; and
a composite protective structure directly adjacent the electrode, wherein the composite protective structure comprises:
an alloy comprising the alkali metal; and
a fluoride salt of the alkali metal,
wherein the fluoride salt of the alkali metal makes up greater than or equal to 0.1 wt % of the composite protective structure, and
wherein the composite protective structure comprises particles having a core-shell structure.
2. A protected electrode structure as in claim 1 , wherein the composite protective structure comprises pores.
3. A protected electrode structure as in claim 1 , wherein the composite protective structure is substantially impermeable to an electrolyte.
4. A protected electrode structure as in claim 1 , wherein the alloy forms the shell of the core-shell structure.
5. A protected electrode structure as in claim 1 , wherein the alkali metal comprises lithium.
6. A protected electrode structure as in claim 1 , wherein the particles comprise a metal-containing species.
7. A protected electrode structure as in claim 6 , wherein the metal-containing species comprises at least one of Sn, Zn, In, Al, Mg, Ga, Ag, Cd, Pb, and Bi.
8. A protected electrode structure as in claim 1 , wherein the alloy comprises at least one of Sn, Zn, In, Al, Mg, Ga, Ag, Cd, Pb, Bi, Sb, Si, Ge, and As.
9. A protected electrode structure as in claim 1 , wherein the particles have an average size of greater than or equal to 5 nm and less than or equal to 2 microns.
10. A protected electrode structure as in claim 1 , wherein the composite protective structure comprises an oxide of the alkali metal that makes up greater than or equal to 0.1 wt % of the protective structure and less than or equal to 70 wt % of the protective structure.
11. A protected electrode structure as in claim 10 , wherein the oxide of the alkali metal makes up greater than or equal to 10 wt % of the composite protective structure and less than or equal to 50 wt % of the protective structure.
12. A protected electrode structure as in claim 1 , wherein the fluoride salt of the alkali metal makes up greater than or equal to 0.1 wt % of the composite protective structure and less than or equal to 50 wt % of the protective structure.
13. A protected electrode structure as in claim 1 , wherein the composite protective structure has a thickness of at least 20 nm and less than or equal to 5 microns.
14. A protected electrode as in claim 1 , wherein the composite protective structure further comprises a metal-containing species in a metallic phase or a metalloid-containing species in a metalloid phase.
15. A protected electrode as in claim 14 , wherein the metal-containing species in the metallic phase comprises a metal that does not form an alloy with the alkali metal.
16. A protected electrode structure as in claim 14 , wherein the metal-containing species in the metallic phase comprises at least one of Cu, Ni, and Fe.
17. A method of forming a protected electrode, comprising:
exposing an electrode comprising an alkali metal to a liquid comprising a metal fluoride salt or a metalloid fluoride salt; and
forming a composite protective structure on the electrode, wherein the composite protective structure comprises an alloy comprising the alkali metal and a fluoride salt of the alkali metal wherein the fluoride salt of the alkali metal makes up greater than or equal to 0.1 wt % of the composite protective structure, and
wherein the composite protective structure comprises particles having a core-shell structure.