Structure-directing agent mediated synthesis of SnS coupled with Ultraphene as highly stable anode material for sodium-ion battery.

Sodium-ion battery (SIB) with abundant resources has been intensively developed as the efficient energy storage device. Tin disulfide (SnS) is one of the attractive anode materials due to its high capacity and two-dimensional structure. Nevertheless, volume expansion and low conductivity result in the poor rate performance and stability. In this study, three strategies are applied to design efficient SnS-based anode materials for the SIB. Two precursor solvents of deionized water (DIW) and ethanol and one structure-directing agent of cetyltrimethylammonium bromide (CTAB) are incorporated to synthesize SnS. The commercial Ulraphene is further mixed with SnS to design composites (U/s-SnS) with different ratios. The optimal SnS and U/s-SnS anodes respectively show the specific capacities of 187.7 and 326.3 mAh/g at 1.6 A/g. After 100 cycles, the U/s-SnS anode still attains specific capacities of 308.7 and 438.9 mAh/g at 1.0 and 0.1 A/g corresponding to capacity retentions of 74.5% and 80.1%, respectively. The excellent rate performance and cycling stability of the U/s-SnS anode are attributed to the smaller charge-transfer resistance and the larger Na diffusion coefficient. This work successfully brings a blueprint for adopting several useful strategies to improve the electrochemical performance of SnS. The effects for all parameters are also carefully explained.