Structurally controlled deposition of silicon onto nanowires

• US 10,707,484 B2
• Filed: 02/02/2018
• Issued: 07/07/2020
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: Amprius Technologies Incorporated (Amprius, Inc.)
• Original Assignee: Amprius, Inc.
• Inventors: Wang, Weijie, Liu, Zuqin, Han, Song, Bornstein, Jonathan, Stefan, Constantin Ionel
• Primary Examiner(s): Eoff, Anca
• Application Number:
  US15/887,809
• Publication Number:
  US 20190088939A1
• Time in Patent Office: 886 Days
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/0428 Chemical vapour deposition
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Provided herein are nanostructures for lithium ion battery electrodes and methods of fabrication. In some embodiments, a nanostructure template coated with a silicon coating is provided. The silicon coating may include a non-conformal, more porous layer and a conformal, denser layer on the non-conformal, more porous layer. In some embodiments, two different deposition processes, e.g., a PECVD layer to deposit the non-conformal layer and a thermal CVD process to deposit the conformal layer, are used. Anodes including the nanostructures have longer cycle lifetimes than anodes made using either a PECVD or thermal CVD method alone.

Claims

1. An anode for a lithium battery, comprising:

a) a substrate;

b) a nanowire template rooted to the substrate;

c) a first amorphous silicon layer substantially coating the nanowire template, the first amorphous silicon layer having a first density; and

d) a second amorphous silicon layer over the first amorphous silicon layer and any exposed nanowire template, the second amorphous silicon layer having a density higher than the density of the first amorphous silicon layer.

2. The anode of claim 1, wherein the first density is less than 2.2 g/cm³.

3. The anode of claim 1, wherein the first density is less than 2.1 g/cm³.

4. The anode of claim 1, wherein the second amorphous silicon layer has a density greater than 2.25 g/cm³.

5. The anode of claim 1, wherein the second amorphous silicon layer has a density at least 0.05 g/cm³ greater than that of the first amorphous silicon layer.

6. The anode of claim 1, wherein the second amorphous silicon layer has a density at least 0.15 g/cm³ greater than that of the first amorphous silicon layer.

7. The anode of claim 1, wherein the first amorphous silicon layer is non-conformal to the nanowire template.

8. The anode of claim 1, wherein the second amorphous silicon layer is conformal to the underlying surface of the first amorphous silicon layer.

9. The anode of claim 1, wherein the hydrogen content of the first amorphous silicon layer is at least 10% atomic.

10. The anode of claim 1, wherein the hydrogen content of the second amorphous silicon layer is no more than 5% atomic.

11. The anode of claim 1, wherein the nanowire template comprises silicide nanowires.

12. The anode of claim 1, wherein the first amorphous silicon layer is between about 5 and 20 microns thick at its maximum diameter.

13. The anode of claim 1, wherein the second amorphous silicon layer is between about 5 and 500 nanometers thick.

14. The anode of claim 1, wherein the second amorphous silicon layer is about 5 and 100 nanometers thick.

15. A lithium battery, comprising:

an anode as in claim 1;

a lithium-containing cathode;

an electrolyte in ionic communication with both the anode and the cathode.

16. An anode for a lithium battery, comprising:

a substrate;

a nanowire template rooted to the substrate;

a first layer substantially coating the nanowire template, the first layer comprising amorphous silicon and having a first density; and

a second layer over the first layer and any exposed nanowire template, the second layer comprising amorphous silicon and having a density higher than the density of the first layer.

17. An anode for a lithium battery, comprising:

a substrate;

a nanowire template rooted to the substrate;

a first layer over the nanowire template, the first layer comprising silicon and having a first density; and

a second layer over the first layer and any exposed nanowire template, the second layer comprising amorphous silicon and having a density greater than the density of the first layer.

18. The anode of claim 17, wherein the first density is less than 2.2 g/cm³.

19. The anode of claim 17, wherein the first density is less than 2.1 g/cm³.

20. The anode of claim 17, wherein the second layer has a density greater than 2.25 g/cm³.

21. The anode of claim 17, wherein the second layer has a density at least 0.05 g/cm³ greater than that of the first layer.

22. The anode of claim 17, wherein the second layer has a density at least 0.15 g/cm³ greater than that of the first layer.

23. The anode of claim 17, wherein the first layer is non-conformal to the nanowire template.

24. The anode of claim 17, wherein the second layer is conformal to the underlying surface of the first layer.

25. The anode of claim 17, wherein the hydrogen content of the first layer is at least 10% atomic.

26. The anode of claim 17, wherein the hydrogen content of the second layer is no more than 5% atomic.

27. The anode of claim 17, wherein the nanowire template comprises silicide nanowires.

28. The anode of claim 17, wherein the first layer is between about 5 and 20 microns thick at its maximum diameter.

29. The anode of claim 17, wherein the second layer is between about 5 and 500 nanometers thick.

30. The anode of claim 17, wherein the second layer is about 5 and 100 nanometers thick.