Patent ID: 7569202

Claim:
Silicon nanosponge particles prepared from a metallurgical grade silicon powder having a starting composition consisting of from about 98.6 to about 99.0 weight percent Si; from about 0.03 to about 0.50 weight percent Fe; from about 0.05 to about 0.2 weight percent Al; from about 0.00 to about 0.08 weight percent Ca; from about 0.00 to about 0.15 weight percent C; and from about 0.2 to about 1.0 weight percent O 2 ; wherein the metallurgical grade silicon powder has an initial particle size ranging from about 1 micron to about 4 microns wherein each silicon nanosponge particle comprises a plurality of nanocrystals with nanopores disposed between the nanocrystals and throughout the entire nanosponge particle; wherein each silicon nanosponge particle has a BET surface area of at least about 142 m 2 /g; and wherein the pores have an average pore diameter ranging from about 2.0 nm to about 8.0 nm as calculated from nitrogen adsorption isotherm data using the Barret-Joyner-Halenda scheme.