Asymmetric anodes for lithium-based energy storage devices

1. An anode for an energy storage device comprising:

a current collector comprising an electrically conductive substrate and a surface layer overlaying a first side of the electrically conductive substrate, wherein the surface layer comprises a metal oxide or a metal chalcogenide;

a lithium storage layer overlaying the surface layer, wherein the lithium storage layer: i) has a total content of amorphous silicon of at least 85 atomic %, and ii) includes less than 10 atomic % carbon; and

a plurality of lithium storage filamentary structures in contact with a second side of the electrically conductive substrate, the second side opposite the first side, wherein the plurality of lithium storage filamentary structures comprises silicon, germanium, tin, or a combination thereof.

2. The anode of claim 1 , wherein the metal oxide comprises a transition metal oxide.

3. The anode of claim 1 , wherein the surface layer comprises the metal chalcogenide, and the metal chalcogenide comprises at least one of sulfur or selenium.

4. The anode of claim 1 , wherein the surface layer has an average thickness in a range of in a range of 0.02 μm to 2 μm.

5. The anode of claim 1 , wherein the electrically conductive substrate comprises stainless steel, titanium, nickel, copper, a conductive carbon, or a combination thereof.

6. The anode of claim 1 , wherein the lithium storage layer has an average thickness in a range from 0.5 μm to 40 μm.

7. The anode of claim 1 , wherein the lithium storage layer is a continuous porous lithium storage layer having an average density from 1.1 g/cm 3 to 2.25 g/cm 3 .

8. The anode of claim 1 , wherein the plurality of lithium storage filamentary structures has an aspect ratio of at least 2.

9. The anode of claim 1 , wherein the plurality of lithium storage filamentary structures has an average height in a range of 0.2 μm to 100 μm.

10. The anode of claim 1 , wherein the plurality of lithium storage filamentary structures has an average maximum width in a range of 0.1 μm to 10 μm.

11. The anode of claim 1 , wherein the plurality of lithium storage filamentary structures further comprises a transition metal silicide or transition metal alloy of germanium.

12. The anode of claim 1 , wherein each lithium storage filamentary structure of the plurality of lithium storage filamentary structures comprises a core filament and a lithium storage coating over the core filament.

13. The anode of claim 12 , wherein the core filament comprises a transition metal silicide or a transition metal alloy of germanium.

14. The anode of claim 12 , wherein the lithium storage coating comprises silicon, germanium, or a mixture thereof.

15. The anode of claim 1 , wherein the lithium storage filamentary structures have a total content of silicon, germanium, or a combination thereof of at least 40 atomic %.

16. The anode of claim 1 , wherein the second side of the electrically conductive substrate comprises a filament growth catalyst material.

17. The anode of claim 1 , wherein the lithium storage layer and the plurality of lithium storage filamentary structures both comprise silicon.

18. The anode of claim 1 , wherein the electrically conductive substrate comprises:

i) a first electrically conductive layer corresponding to the first side of the electrically conductive substrate;

ii) a second electrically conductive layer corresponding to the second side of the electrically conductive substrate; and

iii) an electrically insulating layer interposed between the first electrically conductive layer and the second electrically conductive layer.

19. A lithium-ion battery comprising a cathode and the anode according to claim 1 .

20. The anode of claim 1 , wherein the plurality of lithium storage filamentary structures has a total content of amorphous silicon of at least 80 atomic %.