Electrolyte design enabling practical lithium/sulfur batteries via interfacial manipulation and inhibited polysulfide dissolution

Abstract

To address low stability at the lithium metal anode and lithium polysulfide shuttling is critical for high-energy-density lithium/sulfur (Li/S) pouch cells in practical applications. However, functional electrolytes that are compatible with Li anodes and S cathodes are required to construct more stable interfaces. Herein, we report a highly compatible electrolyte (NBME) containing bis(2-methoxyethoxy)methane (BME) as a single solvent with 1 M lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and 2% LiNO₃ additive. Compared to the traditional DOL/DME blend solvent, better electrochemical performance of 200 cycles in Li/Cu asymmetric cells and over 1200 h of cycling in Li/Li symmetric cells was realized with NBME electrolyte. Improved anode/electrolyte interfacial stability results from the anion-rich solvation sheath, thus forming an inorganic-rich SEI. In addition, the lithium polysulfide (LiPS) shuttle effect could be relieved in NBME electrolyte due to the low solubility of LiPS. Such synergistic effects enable the Li/S pouch cells to achieve 70% capacity retention after 60 cycles.