PASSIVATION OF FRESHLY MILLED SILICON
Herewith is described a process to produce stable, non-pyrophoric silicon nanocrystals as an isolatable powder. The process includes comminuting a silicon feed in a solvent thereby forming a silicon nanoparticle slurry, admixing a dry (water free) reagent with the silicon nanoparticle slurry thereby forming a SiX-coated silicon nanoparticle slurry. The reagent is, preferably, selected from an oxide source, a sulfide source, or a carbide source; where the SiX-coated silicon nanoparticle includes a SiX coating on a silicon nanoparticle and the SiX coating is a silicon-oxide when the reagent is an oxide source, a silicon-sulfide when the reagent is a sulfide source, or a silicon-carbide when the reagent is a carbide source.
1 . A process comprising:
comminuting a silicon feed in a solvent thereby forming a silicon nanoparticle slurry;
admixing a dry reagent with the silicon nanoparticle slurry thereby forming an SiX-coated silicon nanoparticle slurry;
wherein the dry reagent is selected from an oxide source, a sulfide source, or a carbide source; wherein the SiX-coated silicon nanoparticle slurry includes a SiX-coated silicon nanoparticle in the solvent; wherein the SiX-coated silicon nanoparticle includes a SiX coating on a silicon nanoparticle; and wherein the SiX coating is a silicon-oxide when the reagent is an oxide source, a silicon-sulfide when the reagent is a sulfide source, or a silicon-carbide when the reagent is a carbide source.
2 . The process of claim 1 , wherein the silicon feed is comminuted and then the dry reagent is mixed with the silicon nanoparticle slurry.
3 . The process of claim 1 , wherein the silicon feed is comminuted in the presence of the dry reagent.
4 . The process of claim 1 further comprising heating the SiX-coated silicon nanoparticle slurry.
5 . The process of claim 1 further comprising removing the solvent from the SiX-coated silicon nanoparticle slurry.
6 . The process of claim 5 further comprising annealing the SiX-coated silicon nanoparticle.
7 . The process of claim 6 , wherein the SiX coating is a silicon-oxide, and wherein annealing crystallizes the silicon-oxide.
8 . The process of claim 1 , wherein the oxide source is oxygen.
9 . The process of claim 1 , wherein the oxide source is an N-oxide.
10 . The process of claim 1 , wherein the oxide source is selected from sulfur trioxide, carbon dioxide, or a mixture thereof.
11 . The process of claim 1 , wherein the sulfide source is sulfur.
12 . The process of claim 1 , wherein the carbide source is amorphous carbon.
13 . The process of claim 1 , wherein the SiX coating has a thickness of about 0.1 nm or more or about 0.05 μm or less.
14 . The process of claim 13 , wherein the SiX coating has a formula of SiO x where x is about 0.5 to 2; about 0.5 to about 1.9, about 0.5 to about 1.8, about 0.5 to about 1.7, about 0.5 to about 1.6, or about 0.5 to about 1.5.
15 . The process of claim 13 , wherein the SiX coating has a formula of SiS x where x is about 0.5 to 2; about 0.5 to about 1.9, about 0.5 to about 1.8, about 0.5 to about 1.7, about 0.5 to about 1.6, or about 0.5 to about 1.5.
16 . The process of claim 13 , wherein the SiX coating has a formula of SiC x where x is about 0.5 to 2; about 0.5 to about 1.9, about 0.5 to about 1.8, about 0.5 to about 1.7, about 0.5 to about 1.6, or about 0.5 to about 1.5.
17 . The process of claim 13 , wherein the SiX coating is derived from the oxide source, and wherein the oxide source includes a siloxane or a residue of a siloxane.
18 . The process of claim 1 , wherein the silicon nanoparticles and the SiX-coated silicon nanoparticles have an average diameter of about 50 to about 500 nm, about 50 to about 400 nm, about 50 to about 300 nm, about 50 to about 250 nm, or about 50 to about 200 nm.
19 . A process comprising:
comminuting a silicon feed in a solvent and in the presence of an oxide source to form a silicon nanoparticle slurry including silicon nanoparticles coated in silicon-oxide; and
annealing the silicon nanoparticle to crystallize the silicon-oxide.
20 . A process comprising:
comminuting a silicon feed in a solvent thereby forming a silicon nanoparticle slurry in the presence of a dry reagent to form a SiX-coated silicon nanoparticle slurry; and
heating the SiX-coated silicon nanoparticle slurry;
wherein the dry reagent comprises an oxide source, a sulfide source, or a carbide source; wherein the SiX-coated silicon nanoparticle slurry includes a SiX-coated silicon nanoparticle in the solvent; wherein the SiX-coated silicon nanoparticle includes a SiX coating on a silicon nanoparticle; and wherein the SiX coating is a silicon-oxide when the dry reagent is an oxide source, a silicon-sulfide when the dry reagent is a sulfide source, or a silicon-carbide when the dry reagent is a carbide source.