A silicon-containing structure including: a silicon composite including a porous silicon secondary particle and a first carbon flake on a surface of the porous silicon secondary particle; a carbonaceous coating layer on the porous silicon composite, the carbonaceous coating layer comprising a first amorphous carbon; and the silicon composite comprises a second amorphous carbon and has a density that is equal to or less than a density of the carbonaceous coating layer, wherein the porous silicon secondary particle includes an aggregate of silicon composite primary particles, each including silicon, a silicon suboxide on a surface of the silicon, and a second carbon flake on a surface of the silicon suboxide.