Nano-flower spherical SnS2 combined with a special lithium storage mechanism as a multifunctional separator for lithium-sulfur batteries contributes to ultra-high initial discharge specific capacity

The critical factors that limit the electrochemical performance of lithium-sulfur(Li-S)batteries are mainly the“shuttle effect”of polysulfides and the slow redox reaction between lithium polysulfides(LiPSs).Herein,a nano-sphere-type material selfassembled from tin disulfide nanosheets is designed and applied to the Li-S cell separator in this work.The SnS_(2)@PP modified separator not only acts as a dual restriction for LiPSs by chemisorption and physical barrier.At the same time,it improves the catalytic activity of the redox reaction between LiPSs.The SnS_(2)has extremely high electrochemical activity.There,a portion of the lithium ions can be inserted into SnS_(2)to form Li_(x)SnS_(2)and contribute to the capacity during the first discharge of the battery.In addition,Li_(x)SnS_(2)possesses a high degree of stability,and it does not undergo further de-alloying reactions even at the high potential of the Li-S cell.The benefit is that the steady-state Li_(x)SnS_(2)acts as a lithium-containing substance.It can form special Li^(+)channels on the surface of the separator,thus greatly improving the efficiency of Li+transport.The results showed that the SnS_(2)@PP-based cell exhibited extremely high initial discharge specific capacity(1477 m Ah g^(-1)at 0.1 C)and excellent rate performance(631 m Ah g^(-1)at 5 C).Even after 1000 cycles at 2 C,the cell exhibited a low decay rate of 0.06%per cycle on average.In addition,the superior electrochemical performance was obtained even with a high sulfur loading of 5.1 mg cm^(-2)and low electrolyte of E/S=8μL mg^(-1).