Stabilizing Lithium-Sulfur Cells with Practical Loading and Cycling Conditions Using Li2S8-Containing Ethereal Electrolyte Solution

We report on stabilization of Li-S cells cycled with an areal charge/discharge capacity of 2 mAh cm(-2) at current densities of 1-2 mA cm(-2) using ethereal LiTFSI/LiNO3/DOL/DME electrolyte solution containing 0.1M Li2S8. This electrolyte solution enables stable lithium metal stripping-plating both in symmetric Li divide Li and full Li-S cells with composite binder free sulfur impregnated activated carbon fibers cathodes. The addition of Li2S8 substantially extends cycling life of these cells due to the formation of smooth non-dendritic Li metal surface protected with an effective SEI enriched with Li sulfides, sulfites and sulfates species. Symmetric Li divide Li could be cycled stably for more than 1000 h at 1-2 mA cm(-2) with Li2S8-containing electrolyte solutions. Full Li-S cells demonstrate more than 500 stable cycles (at least 3 times more than with Li2S8 free electrolyte solution) at a current density of 1 mA cm(-2) and an areal capacity of 2 mAh cm(-2). The most stable cycling results were achieved for the cells cycled with discharge cut off voltage of 1.9 V preventing the depletion of LiNO3. The use of electrolyte solutions containing liquid lithium poly-sulfides makes possible considerable decrease in the amount of the electrolyte solution and increases the energy density of the cells.