Conductive matrix and sulfur composite
An activated carbon-coated carbon black material having a nitrogen BET surface area of about 850 to 1800 m 2 /g, a packing density of at least 0.8 g/cc as determined at a compressive force of 500 kgf/cm 2 on dry carbon powder, an electrical conductivity of a least 10 S/cm at a compressive force of 500 kgf/cm 2 on dry carbon powder and electrodes and batteries comprising the carbon material. Methods for preparing such carbon materials from sugar, dextrose, oils and carbon black are described. The material is comprised of carbon black particles coated with a porous activated carbon shell.
1. A porous carbon, comprising:
a. a nitrogen BET surface area of about 850 to 1800 m 2 /g;
b. a packing density of at least 0.8 grams per cubic centimeter as determined at a compressive force of 500 kgf/cm 2 on dry carbon powder; and
c. an electrical conductivity of a least 10 S/cm at a compressive force of 500 kgf/cm 2 on dry carbon powder.
2. The porous carbon of claim 1 with a carbon content of at least 94 weight %.
3. The porous carbon of claim 1 with a sulfur content of at least 0.6 weight %.
4. A carbon matrix-sulfur composite, wherein the carbon matrix comprises the porous carbon of claim 1 , wherein sulfur is deposited into the pores of the carbon matrix, and the sulfur content is at least 50 weight % of the carbon matrix-sulfur composite.
5. The carbon matrix-sulfur composite of claim 4 , wherein the sulfur is deposited inside 2-100 nanometer-diameter pores in the carbon matrix.
6. The carbon matrix-sulfur composite of claim 4 , wherein the sulfur is at least 70 weight % of the carbon matrix-sulfur composite and the sulfur is deposited inside 2-100 nanometer-sized pores in the carbon matrix.
7. A cathode for a lithium-sulfur battery comprising the carbon matrix-sulfur composite of claim 4 .
8. A lithium-sulfur battery comprising the cathode of claim 7 .
9. The porous carbon of claim 1 , wherein the packing density is at least 1.0 grams per cubic centimeter at 500 kgf/cm 2 .
10. The porous carbon of claim 1 , wherein pore volume of pores from 2 to 100 nm is at least 0.5 cubic centimeters per gram.
11. The porous carbon of claim 10 , wherein pore volume of pores from 2 to 100 nm is at least 1.0 cubic centimeters per gram.
12. An activated carbon-coated carbon black material made by the steps of:
a. providing a plurality of carbon black particles, a carbohydrate in the form of a refined sugar, and an oil;
b. coating the plurality of carbon black particles with the carbohydrate and the oil;
c. carbonizing the carbohydrate, which is coated on the plurality of carbon black particles, under a nitrogen atmosphere; and
d. activating the carbohydrate, which is carbonized on the plurality of carbon black particles, under a steam or carbon dioxide atmosphere.
13. A carbon matrix-sulfur composite, wherein the carbon matrix is made by the steps of claim 12 , and a carbon matrix-sulfur composite is made by the additional steps of:
a. providing a sulfur powder;
b. mixing the carbon matrix with the sulfur powder;
c. placing the carbon matrix with the sulfur powder inside a pressure vessel;
d. pulling a vacuum on the pressure vessel;
e. heating the pressure vessel to at least 150 degrees Celsius; and
f. heating the carbon matrix and the sulfur powder for a period of time to allow sulfur to deposit inside pores with a diameter from 2 to 100 nm.
14. A cathode for a lithium-sulfur battery comprising the carbon matrix-sulfur composite of claim 13 .
15. A lithium-sulfur battery comprising the cathode of claim 14 .