Template electrode structures for depositing active materials
Provided are examples of electrochemically active electrode materials, electrodes using such materials, and methods of manufacturing such electrodes. Electrochemically active electrode materials may include a high surface area template containing a metal silicide and a layer of high capacity active material deposited over the template. The template may serve as a mechanical support for the active material and/or an electrical conductor between the active material and, for example, a substrate. Due to the high surface area of the template, even a thin layer of the active material can provide sufficient active material loading and corresponding battery capacity. As such, a thickness of the layer may be maintained below the fracture threshold of the active material used and preserve its structural integrity during battery cycling.
1. A method of fabricating a lithium ion cell electrode for use in a lithium ion cell, the method comprising:
receiving a substrate;
forming a nanostructured template comprising a metal silicide on a surface of the substrate; and
forming a layer of an electrochemically active material on the nanostructured template, the electrochemically active material configured to take in and release lithium ions during cycling of the lithium ion cell,
wherein the nanostructured template facilitates conduction of electrical current to and from the electrochemically active material.
2. The method of claim 1 , further comprising, prior to forming the metal silicide template, treating the substrate using one or more techniques selected from the group consisting of oxidation, annealing, reduction, roughening, sputtering, etching, electroplating, reverse-electroplating, chemical vapor deposition, nitride formation, and deposition of an intermediate layer.
3. The method of claim 1 , further comprising forming a metal component on the surface of the substrate, wherein a portion of the metal component is consumed when forming the metal silicide.
4. The method of claim 1 , wherein forming the nanostructured template comprises introducing a silicon containing precursor over the surface of the substrate.
5. The method of claim 1 , further comprising selectively depositing a passivation layer over the nanostructured template prior to forming the layer of the electrochemically active material.
6. The method of claim 1 , wherein forming the layer of the electrochemically active material is performed in a mass transport regime such that a substantially lower concentration of an active material precursor is available at the surface of the substrate than at free ends of the nanostructured template.
7. The method of claim 1 , further comprising changing a composition of active material precursors while forming the layer of the electrochemically active material.
8. The method of claim 1 , wherein the metal silicide is selected from a group consisting of a nickel silicide, cobalt silicide, copper silicide, silver silicide, chromium silicide, titanium silicide, aluminum silicide, zinc silicide, and iron silicide.
9. The method of claim 1 , wherein the nanostructured template comprises silicide containing nanowires.
10. The method of claim 9 , wherein the silicide containing nanowires are between about 1 micrometer and 200 micrometers in length on average.
11. The method of claim 9 , wherein the silicide containing nanowires are less than about 100 nanometers in diameter on average.
12. The method of claim 1 , wherein the layer of the electrochemically active material is at least about 100 nanometers in thickness on average.
13. The method of claim 1 , wherein a volume ratio of the electrochemically active material to the template is at least about 5.
14. The method of claim 1 , further comprising doping the electrochemically active material with one or more of the following materials: phosphorous, boron, gallium, and lithium.
15. The method of claim 1 , further comprising forming a shell over the layer of the electrochemically active material, wherein the shell comprises one or more materials selected from the group consisting of carbon, copper, a polymer, a sulfide, Lithium Phosphorous Oxynitride (LIPON), a metal oxide, and a fluorine containing compound.
16. The method of claim 1 , wherein the electrochemically active material has a theoretical lithiation capacity of at least about 500 mAh/g.
17. A lithium ion cell electrode fabricated by the method of claim 1 .