Electrochemical Reactivation of Dead Li2S for Li-S Batteries in Non-Solvating Electrolytes

The use of non-solvating, or as-called sparingly-solvating, electrolytes (NSEs), is regarded as one of the most promising solutions to the obstacles to the practical applications of Li-S batteries. However, it remains a puzzle that long-life Li-S batteries have rarely, if not never, been reported with NSEs, despite their good compatibility with Li anode. Here, we find the capacity decay of Li-S batteries in NSEs is mainly due to the accumulation of the dead Li2S at the cathode side, rather than the degradation of the anodes or electrolytes. Based on this understanding, we propose an electrochemical strategy to reactivate the accumulated Li2S and revive the dead Li-S batteries in NSEs. With such a facile approach, Li-S batteries with significantly improved cycling stability and accelerated dynamics are achieved with diglyme-, acetonitrile- and 1,2-dimethoxyethane-based NSEs. Our finding may rebuild the confidence in exploiting non-solvating Li-S batteries with practical competitiveness.

Automated summary

The use of non-solvating electrolytes is considered a promising solution for practical applications of Li-S batteries. However, long-life Li-S batteries with non-solvating electrolytes are rarely reported. The capacity decay in these batteries is mainly due to the accumulation of dead Li2S at the cathode side. A proposed electrochemical strategy can reactivate the accumulated Li2S and revive the batteries, leading to improved cycling stability and accelerated dynamics.