Electrode including nanostructures for rechargeable cells
A lithium ion battery electrode includes silicon nanowires used for insertion of lithium ions and including a conductivity enhancement, the nanowires growth-rooted to the conductive substrate.
1. A lithium ion battery electrode comprising:
a conductive substrate having a conductivity of at least 10 3 S/cm 2 ; and
silicon containing nanowires substrate-rooted to the conductive substrate,
the silicon containing nanowires having variable cross-sectional dimensions along the length of the silicon containing nanowires and having tapered profiles with wider ends and narrower ends,
wherein the wider ends are substrate-rooted to the conductive substrates to provide conductive attachment and mechanical support to the silicon containing nanowires with respect to the conductive substrate, wherein the silicon containing nanowires comprise a dopant.
2. The electrode of claim 1 , wherein the silicon containing nanowires further comprise a silicide.
3. A lithium ion battery electrode comprising:
a conductive substrate; and
silicon containing nanowires substrate-rooted to the conductive substrate,
the silicon containing nanowires having variable cross-sectional dimensions along the length of the silicon containing nanowires and having tapered profiles with wider ends and narrower ends,
wherein the wider ends are substrate-rooted to the conductive substrates to provide conductive attachment and mechanical support to the silicon containing nanowires with respect to the conductive substrate, wherein the silicon containing nanowires further comprise a carbide.
4. The electrode of claim 1 , wherein the silicon containing nanowires each comprise a silicide core and a silicon shell.
5. The electrode of claim 1 , wherein the conductive substrate comprises nickel.
6. The electrode of claim 1 , wherein the conductive substrate is provided in the form of a structure selected from the group consisting of a mesh, a perforated sheet, a foam, and a felt.
7. The electrode of claim 1 , the silicon containing nanowires comprise substrate-rooted cores and a layer of an electrochemically active material coating the substrate-rooted cores.
8. The electrode of claim 7 , wherein the electrochemically active material comprises a material selected from the group of consisting silicon, tin, and germanium.
9. The electrode of claim 8 , wherein the substrate-rooted cores comprise a silicide, and wherein the electrochemically active material consists essentially of silicon.
10. The electrode of claim 1 , further comprising a shell coating the silicon containing nanowires.
11. The electrode of claim 10 , wherein the shell comprising a carbon-containing material.
12. The electrode of claim 1 , wherein the silicon containing nanowires each contains a narrow neck located between a substrate-rooted end and a free end of the silicon containing nanowires.
13. The electrode of claim 1 , wherein the silicon containing nanowires have an average aspect ratio of at least about ten.
14. The electrode of claim 1 , wherein the silicon containing nanowires have an average cross-sectional dimension of between about 1 nanometer and 10 microns on average.
15. The electrode of claim 1 , wherein the silicon containing nanowires form a layer over the conductive substrate, the layer having porosity of less than about 75 percent.
16. The electrode of claim 1 , wherein the silicon containing nanowires have an average length of at least about 100 micrometers.
17. The electrode of claim 1 , wherein the average cross-sectional dimension of the wider ends is below the silicon fracture.
18. The electrode of claim 1 , wherein the silicon containing nanowires are growth-rooted to the substrate.
19. A lithium ion battery comprising:
a negative electrode comprising a conductive substrate, the conductive substrate having a conductivity of at least 10 3 S/cm 2 , and silicon containing nanowires substrate-rooted to the conductive substrate,
the silicon containing nanowires having variable cross-sectional dimensions along the length of the silicon containing nanowires and having tapered profiles with wider ends and narrower ends,
wherein the wider ends are substrate-rooted to the conductive substrates to provide conductive attachment and mechanical support to the silicon containing nanowires with respect to the conductive substrate, wherein the silicon containing nanowires comprise a dopant.
20. The electrode of claim 1 , wherein the dopant is a group III or group V element.