Binder-free silicon anodes wrapped in multiple graphene shells for high-performance lithium-ion batteries

Si-based composites wrapped in multiple graphene shells were successfully fabricated as binder-free anodes for Li-ion batteries (LIBs). Reduced graphene oxide (rGO) and Si nanoparticles were prepared as spherical composite structures using a facile spray-drying process. The microspheres were homogeneously incorporated into a 3D porous graphene aerogel (GA) structure using an aerogel synthesis process. The inner rGO shell surrounding the Si nanoparticles promoted an effective electron transfer from the surface of the Si nanoparticles to electrolytes and suppressed the continuous formation of an unstable solid–electrolyte interface layer. Moreover, the 3D, porous GA framework, which demonstrated high electrical conductivity and mechanical stability, promoted the homogeneous dispersion of the Si nanoparticles, an effective and fast Li+ ion diffusion, and the suppression of volume expansion during lithiation. The rGO/Si/GA composite anode constructed by multiple graphene shells had an extremely high initial discharge capacity (1217 mAh g−1), excellent cyclic stability (462 mAh g−1 at 1.0 C after 200 cycles), and superior rate capability (819 mAh g−1 at 10 C) owing to its multilayered structure. We expect that our simple and scalable approach for fabricating Si-based anodes wrapped in multiple graphene shells can contribute to the development of high-performance LIBs for use in electric vehicles.