Stabilized porous silicon structure for highly stable silicon anode and methods of making

A method for making carbon/silicon carbide-coated porous silicon particles, comprising:

• (a) providing porous silicon particles having H-terminated surface Si atoms;
• (b) combining the porous silicon particles with carbon-containing precursor molecules to provide a mixture of the porous silicon particles and carbon-containing precursor molecules, wherein the carbon-containing precursor molecules surround outer surfaces of the porous silicon particles and are infiltrated into pores of the porous silicon particles;
• (c) heating the mixture at a temperature of 120° C. to 350° C. for a time of 10 minutes to 10 hours to break H—Si bonds of a portion of the H-terminated surface Si atoms to provide non-H-terminated surface Si atoms and form bonds between the non-H-terminated surface Si atoms and carbon atoms of some of the carbon-containing precursor molecules, thereby forming intermediate particles comprising Si-carbon-containing precursor moieties and unreacted carbon-containing precursor molecules surrounding the porous silicon particles and infiltrated into the pores;
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• (d) heating the intermediate particles at a temperature ≥400° C. for a time of ≥5 minutes to form SiC from the Si-carbon-containing precursor moieties and carbonize the remaining unreacted carbon-containing precursors, thereby forming particles comprising a porous silicon particle and a heterogeneous layer on the porous silicon particle, the heterogeneous layer comprising a discontinuous SiC coating that is discontinuous across a portion of pore surfaces and across a portion of an outer surface of the porous silicon particle, and a continuous carbon coating that covers (i) outer surfaces of the SiC coating and (ii) remaining portions of the pore surfaces and the outer surface of the porous silicon particle, thereby forming C/SiC-coated porous silicon particles.