Ultralight Electrolyte for High-Energy Lithium-Sulfur Pouch Cells

The high weight fraction of the electrolyte in lithium-sulfur (Li-S) full cell is the primary reason its specific energy is much below expectations. Thus far, it is still a challenge to reduce the electrolyte volume of Li-S batteries owing to their high cathode porosity and electrolyte depletion from the Li metal anode. Herein, we propose an ultralight electrolyte (0.83 g mL(-1)) by introducing a weakly-coordinating and Li-compatible monoether, which greatly reduces the weight fraction of electrolyte within the whole cell and also enables Li-S pouch cell functionality under lean-electrolyte conditions. Compared to Li-S batteries using conventional counterparts (approximate to 1.2 g mL(-1)), the Li-S pouch cells equipped with our ultralight electrolyte could achieve an ultralow electrolyte weight/capacity ratio (E/C) of 2.2 g Ah(-1) and realize a 19.2 % improvement in specific energy (from 329.9 to 393.4 Wh kg(-1)) under E/S=3.0 mu L mg(-1). Moreover, more than 20 % improvement in specific energy could be achieved using our ultralight electrolyte at various E/S ratios.