Process for producing a silicon-carbon composite
Process for producing a silicon-carbon composite powder in which a) a gas stream A containing at least one starting compound of silicon selected from the group consisting of SiH 4 , Si 2 H 6 and Si 3 H 8 , and b) a gas stream B containing at least one starting compound of carbon selected from the group consisting of methane, ethane, propane, ethylene and acetylene are reacted in a hot wall reactor at a temperature of less than 900° C., the reaction mixture is cooled or allowed to cool and the pulverulent reaction product is separated from gaseous materials.
1. A process for producing a silicon-carbon composite powder, the process comprising:
feeding
a) a gas stream A comprising at least one silicon starting compound selected from the group consisting of SiH 4 , Si 2 H 6 and Si 3 H 8 , and
b) a gas stream B comprising at least one carbon starting compound selected from the group consisting of methane, ethane, propane, ethylene and acetylene into a hot wall reactor at a temperature of less than 900° C., to form a reaction mixture, cooling the reaction mixture or allowing the reaction mixture to cool, and separating a pulverulent reaction product, to obtain the silicon-carbon composite powder,
wherein the gas stream B is fed into the hot wall reactor after the gas stream A.
2. The process of claim 1 , wherein the gas stream A and the gas stream B are fed into the hot wall reactor simultaneously, either separately or in a mixture comprising the gas stream A and the gas stream B.
3. The process of claim 1 , wherein an Si/C volume fraction in the silicon-carbon composite powder is in a range of 30:1 to 1:30.
4. The process of claim 1 , wherein the silicon starting compound is SiH 4 and the carbon starting compound is acetylene.
5. The process of claim 1 , further comprising:
feeding at least one inert gas selected from the group consisting of argon and helium into the hot wall reactor.
6. The process of claim 1 , wherein there is a laminar flow through the hot wall reactor.
7. A lithium-ion battery anode comprising a silicon-carbon composite powder, having an Si/C volume fraction in a range of 20:1 to 1:10 and comprising silicon particles having an average diameter of 300 nm or less, wherein a surface of the silicon particles is at least partly encapsulated with an amorphous, carbon-comprising layer having an average layer thickness of less than 200 nm.
8. The lithium-ion battery anode of claim 7 , wherein the silicon particles are amorphous.
9. The lithium-ion battery anode of claim 7 , wherein the amorphous, carbon-comprising layer comprises at least one species selected from the group consisting of an aliphatic, an aromatic and a graphitic species.