Enhanced Cyclic Performance and Lithium Storage Capacity of SnO2/Graphene Nanoporous Electrodes with Three-Dimensionally Delaminated Flexible Structure

To fabricate nanoporous electrode materials with delaminated structure, the graphene nanosheets (GNS) in the ethylene glycol solution were reassembled in the presence of rutile SnO2 nanoparticles. According to the TEM analysis, the graphene nanosheets are homogeneously distributed between the loosely packed SnO2 nanoparticles in such a way that the nanoporous structure with a large amount of void spaces could be prepared. The obtained SnO2/GNS exhibits a reversible capacity of 810 mAh/g; furthermore, its cycling performance is drastically enhanced in comparison with that of the bare SnO2 nanoparticle. After 30 cycles, the charge capacity of SnO2/GNS still remained 570 mAh/g, that is, about 70% retention of the reversible capacity, while the specific capacity of the bare SnO2 nanoparticle on the first charge was 550 mAh/g, dropping rapidly to 60 mAh/g only after 15 cycles. The dimensional confinement of tin oxide nanoparticles by the surrounding GNS limits the volume expansion upon lithium insertion, and the developed pores between SnO2 and GNS could be used as buffered spaces during charge/discharge, resulting in the superior cyclic performances.