Nano-featured porous silicon materials
Porous silicon and methods for preparation and use of the same are disclosed. The porous silicon materials have utility either alone or in combination with other materials, for example, combined with carbon particles for energy storage applications.
1. A nano-featured porous silicon material comprising:
i) a skeletal density less than 2.2 g/cm 3 as measured by helium pycnometry;
ii) a specific surface area between 30 m 2 /g and 230 m 2 /g; and
iii) a pore volume between 0.1 cm 3 /g and 0.5 cm 3 /g,
wherein:
an oxygen content of the porous silicon material is less than 30%; and
the porous silicon material comprises micropores, mesopores and macropores, such that the macropores comprise 10% to 90% of the pore volume.
2. The nano-featured porous silicon material of claim 1 , wherein the skeletal density is less than 2.1 g/cm 3 .
3. The nano-featured porous silicon material of claim 1 , wherein the skeletal density is less than 2.0 g/cm 3 .
4. The nano-featured porous silicon material of claim 1 , having a characteristic thickness of nano features of less than 300 nm.
5. The nano-featured porous silicon material of claim 1 , having a characteristic distance between silicon nano features of the nano features of less than 300 nm.
6. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises a specific surface area between 30 m 2 /g and 100 m 2 /g and a pore volume between 0.1 cm 3 /g and 0.5 cm 3 /g.
7. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises less than 40% micropores, between 30% and 40% mesopores, and between 20% and 30% macropores.
8. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises less than 20% micropores, between 30% and 60% mesopores, and between 20% and 50% macropores.
9. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises less than 10% micropores, between 40% and 70% mesopores, and between 20% and 50% macropores.
10. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises less than 5% micropores, between 40% and 50% mesopores, and between 40% and 50% macropores.
11. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises less than 2% micropores, between 40% and 50% mesopores, and between 50% and 60% macropores.
12. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon exhibits a capacity of at least 1600 mAh/g and an average Coulombic efficiency of at least 0.98 when tested in a lithium ion half-cell cycled between 0.8 V and 0.005 V, where the counter electrode is lithium metal, the electrolyte comprises 1M LiPF 6 in a solvent comprised of 2:1 ethylene carbonate:diethylcarbonate (EC:DEC) and 10% (w/w) fluoroethylenecarbonate (FEC) and employing a polypropylene separator.
13. The nano-featured porous silicon material of claim 12 , wherein the nano-featured porous silicon exhibits a capacity of at least 2300 mAh/g and an average Coulombic efficiency of at least 0.97.
14. The nano-featured porous silicon material of claim 1 , having an oxygen content from 1% to 20% by weight, and an aluminum content from 1% to 30% by weight.
15. The nano-featured porous silicon material of claim 14 , comprising from 1% to 10% by weight aluminum.
16. The nano-featured porous silicon material of claim 1 , wherein the nano-featured porous silicon comprises a Dv50 less than 1000 nm.
17. The nano-featured porous silicon material of claim 1 , having a surface area of 30 m 2 /g to 120 m 2 /g, a pore volume of 0.1 cm 3 /g to 0.3 cm 3 /g, wherein the pore volume is comprised of 5% to 40% micropores, 35% to 70% mesopores, and 30% to 60% macropores.
18. The nano-featured porous silicon material of claim 1 , having a surface area of 30 mg 2 /g to 120 m 2 /g, a pore volume of 0.1 cm 3 /g to 0.18 cm 3 /g, wherein the pore volume is comprised of 5% to 15% micropores, 45-55% mesopores, and 30-45% macropores.
19. The nano-featured porous silicon material of claim 1 , wherein the oxygen content of the porous silicon material is less than 5%.
20. The nano-featured porous silicon material of claim 1 , wherein a carbon content of the porous silicon material is less than 5%.