All-Liquid-Phase Reaction Mechanism Enabling Cryogenic Li-S Batteries.

The sluggish solid-solid conversion kinetics from Li2S4 to Li2S during discharge is considered the main problem for cryogenic Li-S batteries. Herein, an all-liquid-phase reaction mechanism, where all the discharging intermediates are dissolved in the functional thioether-based electrolyte, is proposed to significantly enhance the kinetics of Li-S battery chemistry at low temperatures. A fast liquid-phase reaction pathway thus replaces the conventional slow solid-solid conversion route. Spectral investigations and molecular dynamics simulations jointly elucidate the greatly enhanced kinetics due to the highly decentralized state of solvated intermediates in the electrolyte. Overall, the battery brings an ultrahigh specific capacity of 1563 mAh g-1sulfur in the cathode at -60 °C. This work provides a strategy for developing cryogenic Li-S batteries.