METHODS OF PASSIVATION TO CONTROL OXYGEN CONTENT AND REACTIVITY OF SILICON-CARBON COMPOSITE MATERIALS
Passivated 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 - 58 . (canceled)
59 . A method for preparing passivated silicon-carbon composite particles, the method comprising:
a. providing porous carbon scaffold particles, each comprising a pore volume, wherein the pore volume comprises greater than 70% microporosity;
b. heating the porous carbon scaffold particles to a temperature of 350° C. to 550° C. in the presence of silane gas to deposit an amorphous silicon nanoparticle in the pore volume of the porous carbon scaffold particles, to obtain silicon-carbon composite particles;
c. reducing the temperature to between 100° C. and 200° C.; and
d. introducing a passivation gas for a time sufficient to allow the passivation gas to undergo a self-terminating hydrosilylation reaction with a surface of the amorphous silicon nanoparticle, to obtain passivated silicon-carbon composite particles,
wherein the passivated silicon-carbon composite particles comprise a Z of less than 10, wherein Z = 1.875 x [(M1100 - M)/M1100] x 100%, wherein M1100 is a mass of the passivated silicon-carbon composite particles at 1100° C. and M is the minimum mass of the passivated silicon-carbon composite particles between 800° C. and 1100° C. when the passivated silicon-carbon composite particles are heated under air from about 25° C. to about 1100° C., as determined by thermogravimetric analysis.
60 . The method of claim 59 , wherein the passivated silicon-carbon composite particles comprise a silicon content of 30% to 60% by weight.
61 . The method of claim 59 , wherein the passivated silicon-carbon composite particles comprise a Dv50 between 5 nm and 20 microns.
62 . The method of claim 59 , wherein the passivated silicon-carbon composite particles comprise a φ of greater than or equal to 0.1, 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 0.8 V-0.4 V and Regime III is 0.15 V-0 V.
63 . The method of claim 59 , wherein the passivation gas comprises an alkene or alkyne.
64 . The method of claim 59 , wherein the passivation gas is selected from the group consisting of acetylene, propylene, ethylene, butene, allyloxyethanol, diallyl carbonate, allyl methyl carbonate, allyl ethyl carbonate, allyl glycidyl ether, allyloxy (polyethylene oxide) methyl ether, and allyloxytrimethylsilane.
65 . The method of claim 59 , wherein the passivation gas comprises ethanol.
66 . The method of claim 59 , wherein the passivation gas is selected from the group consisting of dimethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, or vinylene carbonate, or a mixture thereof.
67 . The method of claim 59 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 30 m2/g.
68 . The method of claim 59 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 10 m2/g.
69 . A method for preparing passivated silicon-carbon composite particles, the method comprising:
a. providing porous carbon scaffold particles, each comprising a pore volume, wherein the pore volume comprises greater than 70% microporosity;
b. heating the porous carbon scaffold particles to a temperature of 350° C. to 550° C. in the presence of a process gas comprising silane to deposit silicon in the pore volume, to obtain silicon-carbon composite particles; and
c. alternating the process gas between silane gas and a passivation gas to react the passivation gas with a surface functional group of the silicon, to obtain passivated silicon-carbon composite particles,
wherein the passivated silicon-carbon composite particles comprise a Z of less than 10, wherein Z = 1.875 x [(M1100 - M)/M1100] x 100%, wherein M1100 is a mass of the passivated silicon-carbon composite particles at 1100° C. and M is the minimum mass of the passivated silicon-carbon composite particles between 800° C. and 1100° C. when the passivated silicon-carbon composite particles are heated under air from about 25° C. to about 1100° C., as determined by thermogravimetric analysis.
70 . The method of claim 69 , wherein the passivation gas comprises at least one selected from the group consisting of carbon dioxide, ethylene, propylene, and acetylene.
71 . The method of claim 69 , wherein the passivated silicon-carbon composite particles comprise a silicon content of 30% to 60% by weight.
72 . The method of claim 69 , wherein the passivated silicon-carbon composite particles comprise a Dv50 between 5 nm and 20 microns.
73 . The method of claim 69 , wherein the passivated silicon-carbon composite particles comprise a φ of greater than or equal to 0.1, 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 0.8 V-0.4 V and Regime III is 0.15 V-0 V.
74 . The method of claim 69 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 30 m2/g.
75 . The method of claim 69 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 10 m2/g.
76 . A method for preparing passivated silicon-carbon composite particles, the method comprising:
a. providing porous carbon scaffold particles, each comprising a pore volume, wherein the pore volume comprises greater than 70% microporosity;
b. heating the porous carbon scaffold particles to a temperature of 350° C. to 550° C. in the presence of a process gas comprising silane to deposit silicon in the pore volume, to obtain silicon-carbon composite particles; and
c. contacting the silicon-carbon composite particles with a hydrocarbon gas at a temperature of 300° C. to 700° C. to obtain chemical vapor passivated silicon-carbon composite particles,wherein the passivated silicon-carbon composite particles comprise a Z of less than 10,
wherein Z = 1.875 x [(M1100 - M)/M1100] x 100%, wherein M1100 is a mass of the passivated silicon-carbon composite particles at 1100° C. and M is the minimum mass of the passivated silicon-carbon composite particles between 800° C. and 1100° C. when the passivated silicon-carbon composite particles are heated under air from about 25° C. to about 1100° C., as determined by thermogravimetric analysis.
77 . The method of claim 76 , wherein the hydrocarbon gas comprises at least one selected from the group consisting of acetylene, ethylene, propylene, propane, ethane, methane, butane, and butylene.
78 . The method of claim 76 , wherein the hydrocarbon gas comprises acetylene.
79 . The method of claim 76 , wherein the passivated silicon-carbon composite particles comprise a silicon content of 30% to 60% by weight.
80 . The method of claim 76 , wherein the passivated silicon-carbon composite particles comprise a Dv50 between 5 nm and 20 microns.
81 . The method of claim 76 , wherein the passivated silicon-carbon composite particles comprise a φ of greater than or equal to 0.1, 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 0.8 V-0.4 V and Regime III is 0.15 V-0 V.
82 . The method of claim 76 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 30 m2/g.
83 . The method of claim 76 , wherein the passivated silicon-carbon composite particles comprise a surface area less than 10 m2/g.