Lipophilic Additives for Highly Concentrated Electrolytes in Lithium-Sulfur Batteries

The use of concentrated electrolytes in batteries has been impeded in part by the lack of compatible electrolyte additives for protection of electrodes. Herein, a lipophilic additive tetrabutylammonium iodide (TBAI = [Bu4N]I) was introduced to concentrated electrolyte (CH3CN)(2)LiTFSI/TTE (TTE = 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether) for Li-S batteries. Electrochemical and SEM/EDS analyses showed that the additive provided short-term capacity retention via removal of S deposits by in situ generated I-2. These results strongly suggest lipophilic salts as viable candidates for additives in concentrated electrolytes. (c) 2019 The Electrochemical Society.