Cationic Two-Dimensional Sheets For An Ultralight Electrostatic Polysulfide Trap Toward High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries represent one of the most promising secondary battery systems considering their high theoretical specific capacity and theoretical specific energy.However,the development of these batteries has been greatly hindered by certain problems,especially the low sulfur utilization and fast capacity degradation,which result from the dissolution of the intermediate discharge product,polysulfide,and its diffusion across the separator to the anode side.In this thesis,cationic hydroxide sheets were used as a conformal modification layer on a commercial separator,which served as both physical barrier and chemical trapper,thus efficiently blocking the crossover of polysulfides and improving the cyclic life of Li-S batteries.Taking advantage of the dual roles of the modification layer,the hydroxide sheets loading was minimized to a density of~0.018 mg cm~-22 and a thickness of 20-30 nm,which was lower or thinner compared to most of the recent reports.As a result,the possible accompanying sacrificement in energy density due to incorporation of modifying component would be efficiently avoided.This work demonstrated a new cheap and simple but effective method to improve the cycle performance of Li-S batteries.