Silicon-based anode material for lithium ion battery

1. A process for producing a porous reduced silica fiber, comprising:

providing a solution comprising a silica precursor, a polymer, and a surface active agent;

fiberizing the solution to produce fibers;

heating the fibers to produce silica-based precursor fibers;

subjecting the silica-based precursor fibers to a magnesiothermic reduction to remove at least some oxygen from the silica-based precursor fibers and to produce reduced silica fibers; and

washing the reduced silica fibers in an acid to remove magnesium-bearing reaction products and to produce the porous reduced silica fiber;

wherein the porous reduced silica fiber has a diameter of about 0.1 to about 20 microns and a surface area of about 5 m 2 /g to about 400 m 2 /g,

wherein the porous reduced silica fiber comprises SiO x where x=0-2, and

wherein the porous reduced silica fiber comprises greater than about 20 weight percent silicon.

2. The process of claim 1 , wherein the solution further comprises a solvent selected from water, methanol, ethanol, acetone, octane, benzene, or toluene; and

wherein heating the fibers removes the polymer and the solvent from the solution.

3. The process of claim 1 , wherein the solution has a viscosity of between about 1 and about 5 poise.

4. The process of claim 1 , wherein the solution further comprises a polyethylene oxide, a polyvinyl alcohol, a polyethylene glycol, methyl cellulose, ethyl cellulose, polyvinyl pyrrolidone, or a starch.

5. The process of claim 1 , wherein the solution is free from particles of a size greater than 5 microns.

6. The process of claim 1 , wherein the porous reduced silica fiber has a diameter of about 0.1 to about 15 microns.

7. The process of claim 1 , wherein the porous reduced silica fiber has a surface area of about 30 m 2 /g to about 300 m 2 /g.

8. The process of claim 1 , wherein the porous reduced silica fiber has a porosity of about 0.1 cm 3 /g to about 0.7 cm 3 /g.

9. The process of claim 1 , wherein the porous reduced silica fiber has a median pore diameter of about 1 nm to about 90 nm.

10. A process for producing a porous reduced silica fiber, comprising:

providing a melt comprising silica (SiO 2 ) and at least one of sodium oxide (Na 2 O), boron trioxide (B 2 O 3 ), lithium oxide (Li 2 O), calcium oxide (CaO) and magnesia (MgO);

fiberizing the melt to produce fibers;

treating the fibers to remove at least a portion of non-silica components and produce silica-based precursor fibers;

subjecting the silica-based precursor fibers to a magnesiothermic reduction to remove at least some oxygen from the silica-based precursor fibers and to produce reduced silica fibers; and

washing the reduced silica fibers in a washing acid to remove magnesium-bearing reaction products and to produce the porous reduced silica fiber;

wherein the porous reduced silica fiber has a diameter of about 0.1 to about 20 microns and a surface area of about 5 m 2 /g to about 400 m 2 /g,

wherein the porous reduced silica fiber comprises SiO x where x=0-2, and

wherein the porous reduced silica fiber comprises greater than about 20 weight percent silicon.

11. The process of claim 10 , wherein the washing acid comprises hydrochloric acid, sulfuric acid, nitric acid, acetic acid, chloroacetic acid, or trichloroacetic acid.

12. The process of claim 10 , wherein treating the fibers to remove at least a portion of non-silica components comprises acid leaching the fibers.

13. The process of claim 12 , wherein treating the fibers to remove at least a portion of non-silica components further comprises heat treating the fibers prior to acid leaching the fibers.

14. A porous reduced silica fiber produced by a process comprising:

providing a solution comprising a silica precursor, a polymer, and a surface active agent;

fiberizing the solution to produce fibers;

heating the fibers to produce silica-based precursor fibers;

subjecting the silica-based precursor fibers to a magnesiothermic reduction to remove at least some oxygen from the silica-based precursor fibers and to produce reduced silica fibers; and

washing the reduced silica fibers in an acid to remove magnesium-bearing reaction products and to produce the porous reduced silica fiber;

wherein the porous reduced silica fiber has a diameter of about 0.1 to about 20 microns and a surface area of about 5 m 2 /g to about 400 m 2 /g,

wherein the porous reduced silica fiber comprises SiO x where x=0-2, and

wherein the porous reduced silica fiber comprises greater than about 20 weight percent silicon.

15. The porous reduced silica fiber of claim 14 , wherein the solution further comprises a solvent selected from water, methanol, ethanol, acetone, octane, benzene, or toluene; and wherein heating the fibers removes the polymer and the solvent from the solution.

16. A porous reduced silica fiber produced by a process comprising:

providing a melt comprising silica (SiO 2 ) and at least one of sodium oxide (Na 2 O), boron trioxide (B 2 O 3 ), lithium oxide (Li 2 O), calcium oxide (CaO) and magnesia (MgO);

fiberizing the melt to produce fibers;

treating the fibers to remove at least a portion of non-silica components and produce silica-based precursor fibers;

subjecting the silica-based precursor fibers to a magnesiothermic reduction to remove at least some oxygen from the silica-based precursor fibers and to produce reduced silica fibers; and

washing the reduced silica fibers in an acid to remove magnesium-bearing reaction products and to produce the porous reduced silica fiber;

wherein the porous reduced silica fiber has a diameter of about 0.1 to about 20 microns and a surface area of about 5 m 2 /g to about 400 m 2 /g,

wherein the porous reduced silica fiber comprises SiO x where x=0-2, and

wherein the porous reduced silica fiber comprises greater than about 20 weight percent silicon.