Covalent Bond Hybrid Nanostructure of N-doped rGO and Ultrathin SnS₂ with High Porosity for Lithium-Ion Batteries

The two-dimensionally layered material tin disulfide (SnS2) has a large layer spacing (0.59 nm) that accelerates the diffusion of Li+ and electrons. However, the poor conductivity and huge volume expansion limit its further use. Herein, a covalently tightly assembled SnS2@NRGO hybrid nanostructure with high porosity was successfully synthesized by sacrificing PMMA template support strategies. The high porosity and pore volume of SnS2@NRGO not only increases the permeability of active material and electrolyte and improves the utilization of active material, but also provides buffer space for the huge volume expansion of ultrathin SnS2 during the charging and discharging process. In addition, the strong synergistic effect of the covalent bonding and stable hybridization nanostructure provides an efficient Li+ transport path through the 3D tightly connected NRGO network. N doping introduces a large number of defects and adds more active sites for lithium intercalation. The SnS2@NRGO-3 used as the anodes for LIBs deliver excellent rate performance (540.1 mAh g(-1) at a rate of 30 A g(-1)) and outstanding cycle stability (1031.9 mAh g(-1) after 500 cycles at 5 A g(-1); the capacity degradation rate of 0.048% per cycle), which attributed to stable hybrid nanostructure and high pore volume. Therefore, the SnS2@NRGO created by us would be a very promising candidate for the future advanced high-rate long-life Li+ storage anode.