A New Hybrid Solid/Solvating Sulfur Conversion for Energy‐Dense Lithium‐Sulfur Batteries

To boost the practical energy density of lithium‐sulfur batteries, replacing conventional solvating electrolytes with sparingly solvating ones has shown promise by enabling solid‐state sulfur conversion and reducing electrolyte consumption. However, this approach often compromises sulfur redox kinetics. This study reports a new sulfur conversion pathway distinct from both traditional solvated and sparingly solvated mechanisms. Specifically, sulfur is converted into a mixture of solid and solvated lithium polysulfides (LPSs). Such a hybrid solid/solvating conversion pathway is achieved using a newly formulated moderately solvating electrolyte, accomplishing both lean‐electrolyte operation and fast conversion kinetics for lithium‐sulfur batteries. Methoxyacetonitrile (MAN) is selected as the solvent to formulate the moderately solvating electrolyte due to its high relative permittivity (21) that contributes to a high Li + conductivity (11.7 mS cm −1 for 1M lithium bis(trifluoromethane sulfonyl)imide in MAN) and low donor number (14.6 kcal mol −1 ) that reduces the solubility to LPSs to 1/6 of that in mainstream solvating electrolytes. The as‐formulated MAN electrolyte enables sulfur cathodes to operate at a low electrolyte‐to‐sulfur ratio of 2 μL mg −1 and a low cathode porosity of 52%, displaying excellent prospects for boosting both gravimetric and volumetric energy density.