Passivated silicon-carbon composite materials

A hydrosilylation passivated silicon-carbon composite material, comprising:

• a) a porous carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% microporosity;
• b) nano-sized silicon domains disposed within pores of the porous carbon scaffold, wherein a surface of the nano-sized silicon domains is passivated due to Si—R groups, wherein R comprises:
• (i) an organic functional group comprising one or more of carbon, oxygen, nitrogen, and hydrogen;
• and,
• (ii) one or more optional halogen element;
• c) a silicon content of 30% to 60% by weight;
• d) a surface area of less than 30 m2/g;
• e) a Z of less than 10, wherein Z=1.875×[(M1100−M)/M1100]×100, wherein M1100 is a mass of the passivated silicon-carbon composite material at 1100° C. and M is the minimum mass of the passivated silicon-carbon composite material between 800° C. and 1100° C. when the passivated silicon-carbon composite material is heated under air from about 25° C. to about 1100° C., as determined by thermogravimetric analysis;
• and
• f) 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 0.8V-0.4V and Regime III is 0.15V-0V,
• wherein:
• the surface of the nano-sized silicon domains is passivated using chemical vapor infiltration (CVI) by reacting the surface with an alkene gas or alkyne gas at a temperature ranging from 100° C. to 200° C.;
• and
• the surface of the nano-sized silicon domains comprises Si—H surface groups that react with the alkene gas or the alkyne gas to form the Si—R groups.