Simple Synthesis of Nanocrystalline Tin Sulfide/N-Doped Reduced Graphene Oxide Composites as Lithium Ion Battery Anodes

Composites of nitrogen-doped reduced graphene oxide (NRGO) and nanocrystalline tin sulfides were synthesized, and their performance as lithium ion battery anodes was evaluated. Following the first cycle the composite consisted of Li₂S/Li_xSn/NRGO. The conductive NRGO cushions the stress associated with the expansion of lithiation of Sn, and the noncycling Li₂S increases the residual Coulombic capacity of the cycled anode because (a) Sn domains in the composite formed of unsupported SnS₂ expand only by 63% while those in the composite formed of unsupported SnS expand by 91% and (b) Li percolates rapidly at the boundary between the Li₂S and Li_xSn nanodomains. The best cycling SnS₂/NRGO-derived composite retained a specific capacity of 562 mAh g^-1 at the 200th cycle at 0.2 A g^-1 rate.