Enhanced cyclic performance and lithium storage capacity of SnO ₂/graphene nanoporous electrodes with three-dimensionally delaminated flexible structure

To fabricate nanoporous electrode materials with delaminated slructure, the graphene nanosheets (GNS) in the ethylene glycol solution were reassembled in the presence of rutile Sn0₂ nanoparticles. According to the TEM analysis, the graphene nanosheets are homogeneously distributed between the loosely packed Sn0₂ 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 Sn0₂ nanoparticle. After 30 cycles, the charge capacity of Sn¢yGNS still remained 570 mAh/g, that is, about 70% retention of the reversible capacity, while the specific capacity of the bare Sn0₂ 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 Sn0₂ and GNS could be used as buffered spaces during charge/discharge, resulting in the superior cyclic performances.