New High Donor Electrolyte for Lithium–Sulfur Batteries

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The unparalleled theoretical specific energy of lithium-sulfur (Li-S) batteries has attracted considerable research interest from within the battery community. However, most of the long cycling results attained thus far relies on using a large amount of electrolyte in the cell, which adversely affects the specific energy of Li-S batteries. This shortcoming originates from the low solubility of polysulfides in the electrolyte. Here, 1,3-dimethyl-2-imidazolidinone (DMI) is reported as a new high donor electrolyte for Li-S batteries. The high solubility of polysulfides in DMI and its activation of a new reaction route, which engages the sulfur radical (S₃ •- ), enables the efficient utilization of sulfur as reflected in the specific capacity of 1595 mAh g⁻¹ under lean electrolyte conditions of 5 μLelectrolyte mgsulfur ⁻¹ . Moreover, the addition of LiNO₃ stabilizes the lithium metal interface, thereby elevating the cycling performance to one of the highest known for high donor electrolytes in Li-S cells. These engineered high donor electrolytes are expected to advance Li-S batteries to cover a wide range of practical applications, particularly by incorporating established strategies to realize the reversibility of lithium metal electrodes.