Artificial Solid Electrolyte Interface Film For Protection Lithium Anode Of Lithium-sultur Battery

Lithium metal is an ideal anode material for the development of Li-S batteries with high energy densities because of its high theoretical capacity(3860 mAh g-1)light weight density(0.534 g cm-3)and electro-negative potential(-3.04 V versus standard hydrogen electrode),however the serious lithium corrosion and the growth of lithium dendrites has handled the practical application of Li-S batteries.Here,we demonstrated a simple method which only needed to pretreatment Li foil with different solutions and an artificial solid electrolyte interface film was formed.This SEI film could not only prevent polysulfide from corroding the metallic lithium,but also effectively suppress the formation of dendritic lithium.The details are as follows:1.The P4S10 was synthesized by heating treatment,and pretreated Li foil to obtain the Li3PS4 artificial SEI film.The symmetric Li-Li cell and Li-Cu cell with modified Li anode delivered a stable plating and stripping process during the cycling.Also,the SEI film could be complete after several cycles.Appling in Li-S battery,the initial discharge capacity with modified Li anode was 1228 mAh g-1,after 70 cycles,the capacity still remained at 700 mAh g-1,which was higher than that of the cell with pristine Li anode;what's more,after continuous cycling,the surface of modified lithium anode was relatively smooth and denser with few dendrites growth;the cycling performance of Li-S battery with different Li anodes in the electrolyte without LiN03 was tested,the average Coulombic efficiency of modified Li anode was 89%after 47 cycles,higher than the pristine Li anode(53%),which indicated that the SEI film of Li3PS4 and that formed with LiN03 had the same effect in protecting the lithium anode.2.The Poly(dimethylsiloxane)(PDMS)was selected to pretreat Li foil to obtain the artificial SEI film.The symmetric Li-Li cell and Li-Cu cell with modified Li anode delivered higher Coulombic efficiency,longer life-span.In Li-S battery,the initial discharge capacity of modified Li anode was 1139 mAh g-1,after 100 cycles,the capacity still remained at 761 mAh g-1,which was higher than that of the cell with pristine Li anode;what's more,after several cycles,the surface of modified lithium anode was relatively smooth,while the pristine Li anode was seriously corroded and the surface was covered by a plenty of mossy Li;a higher current rate of 0.2 C performance with the PDMS-modified Li anode of Li-S battery was performed,the specific capacity of 737 mAh g-1 after 300 cycles,and the average Coulombic efficiency was as high as 98.1%.This ascertained that this SEI film was contributed to improve the electrochemistry performance of Li-S cell.