Li + storage properties of SiO 2 @C core-shell submicrosphere and its hollow counterpart synthesized by molecular self-assembly in wet-chemistry condition as anodes for LIBs

SiO 2 @C core-shell submicrospheres (SiO 2 @C) were fabricated via molecular self-assembly process in wet-chemistry condition and followed by post-calcination. SEM and TEM indicated the outer diameter of SiO 2 @C is ∼300–400 nm. The diameter of inner SiO 2 core can be controlled from maximum size to zero by NaOH solution etching. XRD, TG-DSC, BET, Raman and XPS were adopted to reveal its microstructure and elemental composition. Systematic electrochemical tests manifested that the specific capacity of SiO 2 @C reduces at the beginning then increases with the decrease of SiO 2 core diameter. The underlying Li + storage mechanism is discussed and analyzed, which illustrates that the effective utilization of active sites is the key for electrochemical performance when SiO 2 @C used as anode material for LIBs. And the completely etched hollow mesoporous carbon sphere without SiO 2 core (HMCS, SiO 2 @C-12 h) exhibited the highest capacity and rate capability (349.2 mA h/g at 100 mA/g after 200 cycles; 316.0 mA h/g at 400 mA/g), which is due to the effective Li + active sites benefitted from its conductive and porous carbon network.