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; 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.
2 . The electrode of claim 1 , wherein the silicon containing nanowires further comprise a silicide.
3 . The electrode of claim 1 , 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 silicon containing nanowires consist essentially of silicon.
18 . The electrode of claim 1 , wherein the average cross-sectional dimension of the wider ends is below the silicon fracture.
19 . The electrode of claim 1 , wherein the silicon containing nanowires are growth-rooted to the substrate.
20 . A lithium ion battery comprising:
a negative 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.