COMPOSITE MATERIALS WITH TUNABLE POROSITY, PREPARATION AND USES THEREOF
Provided herein are composite materials for use in an electrical energy storage system (e.g., high-capacity batteries) and methods for preparing the same. The composite materials of the present disclosure comprise a three-dimensional carbon network and optional silicon particles. The composite materials further comprise macropores, at least some of which are formed by carbonizing sacrificial particles dispersed throughout a three-dimensional network. The macropores advantageously provide a space to accommodate the strain and stress in the electrode structure due to volume changes of silicon (particles) during charging and discharging of the electrical energy storage systems.
1 . A composite material comprising:
a three-dimensional carbon network, wherein the three-dimensional carbon network comprises micropores, mesopores, and macropores, wherein the macropores constitute a volume fraction of greater than about 50% of a total pore volume of the three-dimensional carbon network, and wherein the micropores constitute a volume fraction of about 10% to about 50% of the total pore volume of the three-dimensional carbon network; and
wherein the composite material has a skeletal density ranging from about 0.5 to about 2.5 g/cm 3 as measured by mercury pycnometry.
2 . The composite material of claim 1 , wherein the mesopores constitute a volume fraction of less than about 10% of the total pore volume three-dimensional carbon network or less than about 5% of the total pore volume three-dimensional carbon network.
3 . The composite material of claim 1 , wherein the macropores constitute a volume fraction of over about 50% of a total pore volume three-dimensional carbon network, the mesopores constitute a volume fraction of less than 10% of a total pore volume three-dimensional carbon network, and the micropores constitute a volume fraction equal to the remainder of the total pore volume three-dimensional carbon network.
4 . The composite material of claim 1 , wherein the volume fraction of the macropores is at least 1.5 times the volume fraction of the micropores.
5 . The composite material of claim 1 , wherein the volume fraction of the macropores is about 1.5 times the volume fraction of the micropores to about 2.5 times the volume fraction of the micropores.
6 . The composite material of claim 1 , wherein the volume fraction of the macropores is at least 10 times the volume fraction of the mesopores.
7 . The composite material of claim 1 , wherein a total porosity of the three-dimensional carbon network is greater than about 10%.
8 . The composite material of claim 1 , wherein the volume of the macropores of the three-dimensional carbon network is from about 0.1 cm 3 /g to about 0.3 cm 3 /g.
9 . The composite material of claim 1 , wherein a total pore volume of the three-dimensional carbon network is from about 0.1 cm 3 /g to about 0.4 cm 3 /g.
10 . The composite material of claim 1 , wherein the composite material is in the form of a bead.
11 . The composite material of claim 1 , wherein the three-dimensional carbon network comprises amorphous carbon.
12 . The composite material of claim 1 , wherein the three-dimensional carbon network is a xerogel, an aerogel, an ambigel, an aerogel-xerogel hybrid material, an aerogel-ambigel hybrid material, an aerogel-ambigel-xerogel hybrid material, or a combination thereof.
13 . The composite material of claim 1 , further comprising about 20% to about 85% silicon.
14 . The composite material of claim 13 , wherein at least a portion of the silicon is entrapped within the three-dimensional carbon network.
15 . The composite material of claim 13 , wherein the silicon comprises silicon particles.
16 . The composite material of claim 15 , wherein the silicon particles are disposed adjacent to the macropores.
17 . The composite material of claim 15 , wherein the silicon particles have an oxygen content between 2% and 40%.
18 . The composite material of claim 15 , wherein a total volume of the macropores is about 1 to about 5 times greater than a total volume of the silicon particles.
19 . The composite material of claim 13 , wherein the composite material has a silicon loading of about 2 wt % to about 30 wt %, and wherein the three-dimensional carbon network has a total porosity of about 5% to about 50%, and wherein the three-dimensional carbon network has a total pore volume of about 0.10 mL/g to about 0.40 mL/g.
20 . The composite material of claim 13 , wherein the composite material has a silicon loading of about 30 wt % to about 70 wt %, and wherein the three-dimensional carbon network has a total porosity of about 45% to about 70%, and wherein the three-dimensional carbon network has a total pore volume of about 0.40 mL/g to about 1.0 mL/g.
21 . The composite material of claim 13 , wherein the composite material has a silicon loading of about 70 wt % to about 98 wt %, and wherein the three-dimensional carbon network has a porosity of about 65% to about 75%, and wherein the three-dimensional carbon network has a porosity of about 0.90 mL/g to about 1.4 mL/g.
22 . The composite material of claim 1 , further comprising lithium and/or a lithium salt.