Spray-Drying-Induced Assembly of Skeleton-Structured SnO2/Graphene Composite Spheres as Superior Anode Materials for High-Performance Lithium-Ion Batteries

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.