Tin disulfide nanosheets encapsulated by elemental sulfur for advanced sodium ion batteries

Tin disulfide (SnS 2 ) is a promising anode material for sodium ion storage. In this study, we present a SnS 2 /4S composite with a molar ratio of 1:4 between SnS 2 and S, which was prepared through a simple melt-diffusion method, showing excellent sodium ion storage performance. The elemental sulfur in the composite provides additional capacity with its high specific capacity (1675 mAh g −1 ) and facilitates the interfacial charge transfer between the electrode and the electrolyte because soluble polysulfide anions can be formed during charge and discharge. Thus, the specific capacity of SnS 2 /4S has been maintained at 540.2 mAh g −1 after 150 cycles at a high current density of 5 A g −1 . In addition, the initial discharge capacity of the full cell SnS 2 /4S||Na 3 V 2 (PO 4 ) 3 is 555.1 mAh g −1 with a capacity retention of 95.7 % during 50 cycles. Our work provides a new composite engineering approach for the sodium ion storage study of SnS 2 .