Silicon carbon composites comprising ultra low Z
Silicon-carbon composite materials and related processes are disclosed that overcome the challenges for providing amorphous nano-sized silicon entrained within porous carbon. Compared to other, inferior materials and processes described in the prior art, the materials and processes disclosed herein find superior utility in various applications, including energy storage devices such as lithium ion batteries.
1. A silicon-carbon composite comprising:
a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 80% microporosity;
b. a silicon content of 30% to 60% by weight;
c. a Z of less than 5, wherein Z=1.875×[(M1100−M800)/M1100]×100%, wherein M1100 is a mass of the silicon-carbon composite at 1100° C. and M800 is a mass of the silicon-carbon composite at 800° C. when the silicon-carbon composite is heated under air from about 25° C. to about 1100° C., as determined by thermogravimetric analysis;
d. a surface area less than 30 m 2 /g; and
e. a φ of greater than or equal to 0.12, wherein φ=(Max peak height dQ/dV in Regime I)/(Max peak height dQ/dV in Regime III), wherein dQ/dV is measured in a half-cell coin cell, and Regime I is 0.8V-0.4V and Regime III is 0.15V-0V.
2. The silicon-carbon composite of claim 1 , wherein the pore volume comprises greater than 90% microporosity.
3. The silicon-carbon composite of claim 2 , wherein the pore volume comprises greater than 95% microporosity.
4. The silicon-carbon composite of claim 2 , comprising a surface area less than 5 m 2 /g.
5. The silicon-carbon composite of claim 3 , comprising a surface area less than 5 m 2 /g.
6. The silicon-carbon composite of claim 5 , comprising a silicon content of 40% to 60% by weight.
7. The silicon-carbon composite of claim 2 , comprising a surface area less than 10 m 2 /g.
8. The silicon-carbon composite of claim 3 , comprising a surface area less than 10 m 2 /g.
9. The silicon-carbon composite of claim 2 , comprising a silicon content of 40% to 60% by weight.
10. The silicon-carbon composite of claim 1 , comprising a surface area less than 10 m 2 /g.
11. The silicon-carbon composite of claim 10 , comprising a silicon content of 40% to 60% by weight.
12. The silicon-carbon composite of claim 1 , comprising a surface area less than 5 m 2 /g.
13. The silicon-carbon composite of claim 1 , comprising a silicon content of 40% to 60% by weight.
14. The silicon-carbon composite of claim 1 , wherein the Z is less than 4.
15. The silicon-carbon composite of claim 1 , wherein the Z is less than 3.
16. The silicon carbon composite of claim 1 , wherein the φ is greater than or equal to 0.13.
17. The silicon carbon composite of claim 1 , wherein the φ is greater than or equal to 0.14.
18. The silicon carbon composite of claim 1 , wherein the silicon-carbon composite comprises a Dv50 ranging from 5 nm to 20 microns.
19. The silicon carbon composite of claim 1 , wherein the silicon-carbon composite comprises a capacity of greater than 900 mA/g.
20. The silicon-carbon composite of claim 1 , further comprising lithium ions.