A novel electrolyte approach for a lithium-sulfur secondary battery is presented, realistically portrayed on pouch cell level, with its decisive element being a new electrolyte system, a mixture of a hydrofluoro ether and sulfolane. The hereby suppressed polysulfide solubility enables high discharge capacities and requires only very low electrolyte excess (< 2.6 μL mg S −1 ) achieving high coulomb efficiencies above 94% (capacity retention of 77% over 40 cycles) without the necessity of adding lithium nitrate for shuttle suppression. Due to the low volatility, this adopted electrolyte concept promises significant benefits for large operational battery units.

A low‐density electrolyte composition is introduced for lithium–sulfur (Li–S) batteries with intrinsic and effective polysulfide shuttle suppression. Hexyl methyl ether (HME) is used in combination with 1,3‐dioxolane (DOL) as a solvent for the Li–S battery electrolyte. The choice of solvent limits the dissolution of polysulfides, leading to successful suppression of the parasitic polysulfide shuttle. Hence, high coulombic efficiencies of 98% can be obtained in coin cells for over 50 cycles. The impact of the specifically adapted electrolyte solvent is studied systematically by varying solvent combinations in order to enable the development of light innovative shuttle suppressing electrolytes. In contrast to concepts relying on hydrofluoro ether dilution, the presented electrolyte features a significantly reduced mass density at 2 m lithium bis(trifluoromethanesulfonylimide) (LiTFSI) conductive salt enabling significant weight reduction on the Li–S prototype cell level, thus, allowing energy densities up to 400 Wh kg−1.

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