Composite carbon materials comprising lithium alloying electrochemical modifiers
The present application is generally directed to composites comprising a hard carbon material and an electrochemical modifier. The composite materials find utility in any number of electrical devices, for example, in lithium ion batteries. Methods for making the disclosed composite materials are also disclosed.
1. A method for preparing a silicon-carbon composite, the method comprising:
i) providing an amorphous pyrolyzed and activated porous carbon material having a total pore volume ranging from 0.6 cc/g to 1.0 cc/g
ii) heating the amorphous pyrolyzed and activated porous carbon material in an inert atmosphere to a heat treatment dwell temperature of 500 to 2400 C to yield a heat-treated carbon material
iii) contacting the heat-treated carbon material with a gas comprising silane at a temperature between 400° C. and 500° C., thereby depositing elemental silicon in a pore of the heat treated carbon material to form the silicon-carbon composite.
2. The method of claim 1 , wherein heat treatment dwell temperature is 650° C. to 1800° C.
3. The method of claim 1 , wherein heat treatment dwell temperature is 1000° C. to 1200° C.
4. The method of claim 1 , wherein the inert atmosphere comprises nitrogen gas.
5. The method of claim 1 , where heat treatment dwell time is 10 to 120 minutes.
6. The method of claim 1 , where heat treatment dwell time is 120 to 480 minutes.
7. The method of claim 1 , wherein the heat treated carbon material is contacted with the gas comprising silane for a period of time ranging from 5 minutes to 5 hours.
8. The method of claim 1 , wherein the heat treated carbon material is contacted with the gas comprising silane in a kiln or fluidized bed.
9. The method of claim 8 , wherein the kiln is a rotary kiln.
10. The method of claim 1 , wherein the amorphous activated porous carbon material is contacted with the gas comprising silane at a pressure below atmospheric pressure.
11. The method of claim 1 , wherein the amorphous activated porous carbon material has a fractional pore surface area of pores at or below 100 nm that comprises at least 50% of the total pore surface area.
12. The method of claim 1 , wherein the amorphous activated porous carbon material has a fractional pore surface area of pores at or below 100 nm that comprises at least 90% of the total pore surface area.
13. The method of claim 1 , wherein the amorphous activated porous carbon material comprises particles having a median particle diameter ranging from 1 micron to 10 microns.