Redox Comediation with Organopolysulfides in Working Lithium-Sulfur Batteries

Abstract

Summary Lithium-sulfur (Li–S) battery affords an ultrahigh theoretical energy density of 2,600 Wh kg−1 as a promising next-generation energy storage technique, whose actual performance is heavily dependent on the sulfur redox kinetics. Lithium polysulfide intermediates play a decisive role on the complex sulfur redox reactions but are unfortunately insufficient to afford rapid kinetics, rendering reduced specific capacity especially at high rates. Herein, a redox comediation strategy is proposed and an organopolysulfide (di-t-butyl disulfide, DtbDS) is introduced as a model comediator to accelerate the sulfur redox kinetics. Concretely, DtbDS reacts with lithium polysulfides and provides a kinetically favorable pathway for polysulfide conversion. Consequently, high-rate (4 C), high-sulfur-loading (5 mg cm−2), or lean-electrolyte (5.0 μL mgS−1) Li–S batteries are realized. The redox comediation strategy demonstrates a novel approach to promote the sulfur redox kinetics for high-performance Li–S batteries and inspires more redox comediators represented by DtbDS.