A novel interlayer-expanded tin disulfide/reduced graphene oxide nanocomposite as anode material for high-performance sodium-ion batteries

As a kind of negative electrode material for sodium-ion batteries (SIBs), tin-based active compounds have attracted numerous research efforts in recent years due to relatively high theoretical capacity. However, sluggish reaction kinetics for large-radius sodium ions hinders the practical application of layered tin-based anodes such as tin disulfide (SnS2) in SIBs. In this study, polyethylene glycol (PEG) is introduced as an intercalant and reduced graphene oxide (rGO) is utilized as the substrate to prepare a novel PEG-SnS2/rGO composite with expanded layer spacing (0.921 nm) through a facile hydrothermal process. SnS2 flakes in a size range of 50-100 nm are uniformly grown on the graphene sheet, the CS covalent bonding demonstrates a tight connection between the active SnS2 particles and the graphene skeleton, which is conductive to convenient charge transfer during the electrochemical process. Owing to the significantly improved sodium ions transport kinetics and fast electronic conductive network, the PEG-SnS2/rGO composite presents a high capacitance contribution of 90.69% at a scan rate of 0.6 mV s-1. It delivers a high reversible capacity of 960.6 mAh g-1 at 0.1 A g-1, good cycling performance with 770 mAh g-1 remained after 100 charge/discharge cycles, and excellent rate capability with an ultrahigh capacity of 720 mAh g-1 at 5 A g-1. This work provides new insights into the design of a kinetically favorable anode material for SIBs.