Replenish the Electron-Deficient State of Carbonyl Carbon Atoms to Achieve Stable Li–S Battery

Carbonate-based electrolytes are widely used in Li-ion batteries (LIBs) due to their safe, stable properties and wide operating temperature range. However, the nucleophilic attack at carbonyl carbon atoms by polysulfide anions and the low solubility of lithium nitrate (LiNO₃<0.1 m) in carbonate-based electrolytes seriously hinder the application of lithium–sulfur (Li–S) batteries in carbonate-based electrolytes. Herein, the electrophilicity of carbonyl carbon atoms is gradually reduced through solvent molecules redesign, eliminated the attack of polysulfide anions on carbonyl carbon atoms, and also changed the intermolecular interactions in the electrolyte, improving the solubility of LiNO₃ (>1.0 m) and forming stable LiN_xO_y-containing SEI on the surface of the lithium metal. The assembled Li–S battery with these designed solvent molecules delivers an initial discharge capacity of 1251.7 mAh g⁻¹ at 0.1C. In addition, the lithium–sulfur battery assembled with the designed solvent molecule has a discharge capacity of 631 mAh g⁻¹ after 420 cycles at 0.2 C, with a capacity retention of ≈60%. Moreover, the Li||Li symmetrical cell shows stable cycle performance over 1200 h at 0.5 mA cm⁻² and 0.5 mAh cm⁻².