Samsung patents layered silicon coating for better lithium batteries

1. A silicon-containing composite comprising: a porous core comprising a porous silicon composite secondary particle; and a shell on a surface of the porous core and surrounding the porous core, wherein the porous silicon composite secondary particle comprises an aggregate of silicon composite primary particles having a major axis, each comprising silicon, a silicon suboxide on a surface of the silicon, and a first graphene on a surface of the silicon suboxide, wherein the shell comprises a second graphene, and wherein the first graphene and the second graphene comprise at least one element of nitrogen, phosphorus, and sulfur, wherein an amount of the at least one element of nitrogen, phosphorus, and sulfur in the second graphene shell is about 0.05 atomic percent to about 0.2 atomic percent at a surface depth of 10 nanometers or less from a surface of the second graphene shell of the secondary particle, as analyzed by X-ray photoelectron spectroscopy, wherein the silicon-containing composite comprises a first core/shell structure and a second core/shell structure, the first core/shell structure comprises the porous core comprising the porous silicon composite secondary particle and the second graphene shell on the surface of the porous core, wherein a thickness of the second graphene shell is 10 nm to 5000 nm, and the second core/shell structure comprises a core comprising the silicon and the silicon suboxide on the surface of the silicon, and the shell of the second core/shell structure comprises the first graphene disposed primarily within the porous core of the silicon-containing composite and on the surface of the silicon suboxide, and the second graphene has a higher density than the first graphene.