Three-dimensional skeleton-structured assemblies of graphene sheets decorated with SnO2 nanocrystals are fabricated via a facile and large-scalable spray-drying-induced assembly process with commercial graphene oxide and SnO2 sol as precursors. The influences of different parameters on the morphology, composition, structure, and electrochemical performances of the skeleton-structured SnO2/graphene composite spheres are studied by XRD, TGA, SEM, TEM, Raman spectroscopy, and N2 adsorption-desorption techniques. Electrochemical properties of the composite spheres as the anode electrode for lithium-ion batteries are evaluated. After 120 cycles under a current density of 100 mA g-1, the skeleton-structured SnO2/graphene spheres still display a specific discharge capacity of 1140 mAh g-1. It is roughly 9.5 times larger than that of bare SnO2 clusters. It could still retain a stable specific capacity of 775 mAh g-1 after 50 cycles under a high current density of 2000 mA g-1, exhibiting extraordinary rate ability. The superconductivity of the graphene skeleton provides the pathway for electron transportation. The large pore volume deduced from the skeleton structure of the SnO2/graphene composite spheres increases the penetration of electrolyte and the diffusion of lithium ions and also significantly enhances the structural integrity by acting as a mechanical buffer.
Keywords: graphene; lithium-ion battery; skeleton structure; spray drying; tin dioxide.