Ultrasmall SnS2 nanoparticles anchored on well-distributed nitrogen-doped graphene sheets for Li-ion and Na-ion batteries

Abstract

Well-distributed graphene sheets doped with nitrogen (NGSs) were prepared via a thermal annealing strategy with the use of cyanamide. The cyanamide can efficiently restrain the conglomeration of the resultant graphene sheets and simultaneously ensure the doping of nitrogen. Followed by the next-step of the low-temperature solvothermal route, uniform ultrasmall tin sulfide (SnS₂) nanocrystals were readily grown on the preformed NGS (denoted as SnS₂–NGS). Benefiting from the synergistic function between NGSs and SnS₂, the resultant composites exhibit excellent electrochemical performance. When evaluated as anode materials for lithium-ion batteries (LIBs), SnS₂–NGS with a moderate weight ratio of SnS₂ delivers outstanding electrochemical performance giving a high reversible capacity of 1407 mA h g⁻¹ at 200 mA g⁻¹ after 120 cycles. The composites can also maintain a reversible capacity of about 200 mA h g⁻¹ at a high current density of 10 A g⁻¹. The lithium-ion storage ability of the prepared SnS₂–NGS electrode is at the top rank in comparison with those of other studies. The obtained composites also achieved good sodium storage ability.