An ordered mesoporous network consisting of carbon-coated ultrasmall SnO2 nanoparticles with enhanced Lithium storage

Abstract

An unique ordered mesoporous network consisting of carbon-coated SnO2 nanoparticles (NPs) is developed by a facile self-assemble strategy via a solvethermal route in which employs N,N-dimethylformamide/H2O as mixture solvent and polyvinyl pyrrolidone as barrier agent and carbon source. The SnO2-NPs with an uniform dimension of ~5 nm are observed to interconnect with each other, and assemble into high-compact blocks where abundant mesopores with an average diameter of ~4 nm are found throughout the body. The carbon coating with a thickness of <1 nm are confirmed to exist on these SnO2-NPs, which is of great importance to avoid the severe sintering that occurs in the case of bare SnO2-NPs. Furthermore, the carbon coating plays roles in enhancing conductivity and keeping the active particles from being directly contacted with electrolyte, and thus contributes to enhanced reversible capacity of 949 mAh g−1 and improved initial Coulombic efficiency. The composite electrode with a high tap density of 2.0 g cm−3 exhibits substantially elevated electrochemical performances, such as a charge capacity of 565 mAh g−1 vs 223 mAh g−1 of common SnO2-NPs after 60 cycles and greatly improved rate capability, indicating the promising applications of this advanced micro-nano architecture for next-generation lithium-ion batteries.