Ultrathin SnS2 Nanoparticles on Graphene Nanosheets: Synthesis, Characterization, and Li-Ion Storage Applications

Ultrathin SnS2 nanoparticle decorated graphene nanosheet (GNS) electrode materials with delaminated structure were prepared using stepwise chemical modification of graphene oxide (GO) nanosheets at very dilute conditions, followed by a hydrothermal treatment. The chemical modification of the graphene nanosheet surface with Sn ions enables the precipitation of ultrathin nanoparticles. The TEM analysis reveals the SnS2 nanoparticles are homogeneously distributed on the loosely packed graphene surface in such a way that the GNS restacking was hindered. X-ray photoelectron spectroscopic analysis reveals the bonding characteristics of the SnS2 on the GNS. The obtained nanocomposite exhibits a reversible capacity of 1002 mAh/g which is significantly higher than its calculated theoretical capacity (584 mAh/g). Furthermore, its cycling performance is enhanced and after SO cycles, and the charge capacity still remained 577 mAh/g, which is very close to its theoretical capacity. Due to the synergic effect, the Li-ion storage capacity observed for nanocomposites is much higher than its theoretical capacity. The ultrathin size (2 nm) and dimensional confinement of tin sulfide nanoparticles by the surrounding GNS limit the volume expansion upon lithium insertion, and the nanoporous structures serve as buffered spaces during charge/discharge and result in superior cyclic performances by facilitating the electrolyte to contact the entire nanocomposite materials and reduce lithium diffusion length in the nanocomposite,