Submicron Sized Silicon Powder with Low Oxygen Content

Abstract

A submicron sized Si based powder having an average primary particle size between 20 nm and 200 nm, wherein the powder has a surface layer comprising SiO x , with 0<x<2, the surface layer having an average thickness between 0.5 nm and 10 nm, and wherein the powder has a total oxygen content equal or less than 3% by weight at room temperature. The method for making the powder comprises a step where a Si precursor is vaporized in a gas stream at high temperature, after which the gas stream is quenched to obtain Si particles, and the Si particles are quenched at low temperature in an oxygen containing gas.

1 - 16 . (canceled) 
     
     
         17 . A Si powder having an average primary particle size between 20 nm and 200 nm, wherein the powder has a SiOx surface layer, with 0<x<2, the surface layer having an average thickness between 0.5 nm and 10 nm, and wherein the powder has a total oxygen content equal or less than 3% by-weight at room temperature. 
     
     
         18 . The Si powder of  claim 17 , wherein the surface layer has an average thickness between 0.5 nm and 5 nm. 
     
     
         19 . The Si powder of  claim 17 , having an oxidized SiOx surface layer with 1≤x<2. 
     
     
         20 . The Si powder of  claim 17 , having a purity of at least 98 at % Si. 
     
     
         21 . The Si powder of  claim 17 , having a total oxygen content less than 4% by weight after being aged for 1 hour at 500° C. under atmospheric conditions and in air. 
     
     
         22 . The Si powder of  claim 17 , having a total oxygen content less than 5% by weight after being aged for 1 hour at 700° C. under atmospheric conditions and in air. 
     
     
         23 . The Si powder of  claim 17 , further comprising an element M selected from the group consisting of transition metals, metalloids, Group IIIa elements and carbon. 
     
     
         23 . The Si powder of  claim 23 , wherein M comprises either one of more elements selected from the group consisting of nickel, copper, iron, tin, aluminium and cobalt. 
     
     
         24 . A Li-ion secondary battery comprising the Si powder of  claim 17  as a negative electrode material. 
     
     
         25 . A method for manufacturing the Si powder of  claim 17 , comprising:
 providing a Si precursor,   providing a gas stream at a temperature of at least 1727° C.,   injecting the Si precursor into the gas stream, thereby vaporizing the Si precursor,   quenching the gas stream carrying the vaporized Si precursor to a temperature below 1327° C., thereby obtaining Si particles,   passivating the Si particles in an oxygen containing gas at a temperature below 700° C., and   separating the Si particles from the gas stream after passivation.   
     
     
         26 . The method of  claim 25 , wherein passivation is performed at a temperature below 450° C. 
     
     
         27 . The method of  claim 26 , wherein passivation is performed at a temperature between room temperature and 100° C. 
     
     
         28 . The method of  claim 25 , wherein the gas stream is provided by a gas burner, a hydrogen burner, an RF plasma or a DC arc plasma. 
     
     
         29 . The method of  claim 25 , wherein passivation is performed in an oxygen containing gas comprising one or more additional components selected from the group consisting of Ar, N2, H2, CO and CO2. 
     
     
         30 . The method of  claim 29 , wherein the oxygen containing gas is a mixture of oxygen and nitrogen, with less than 1% oxygen by weight. 
     
     
         31 . The method of  claim 25 , wherein passivation is carried out for a period of less than 60 minutes. 
     
     
         32 . The method of  claim 31 , wherein passivation is carried out for a period of less than 10 minutes. 
     
     
         33 . The method of  claim 25 , wherein the gas stream is provided in a radio frequency inductively coupled plasma, and wherein the gas stream comprises argon gas.