Dual-Functional Organotelluride Additive for Highly Efficient Sulfur Redox Kinetics and Lithium Regulation in Lithium-Sulfur Batteries

High energy density and low cost made lithium-sulfur (Li-S) batteries appealing for the next-generation energy storage devices. However, their commercial viability is seriously challenged by serious polysulfide shuttle effect, sluggish sulfur kinetics, and uncontrollable dendritic Li growth. Herein, a dual-functional electrolyte additive, diphenyl ditelluride (DPDTe) is reported for Li-S battery. For sulfur cathodes, DPDTe works as a redox mediator to accelerate redox kinetics of sulfur, in which Te radical-mediated catalytic cycle at the solid-liquid interface contributes significantly to the whole process. For lithium anodes, DPDTe can react with lithium metal to form a smooth and stable organic-inorganic hybrid solid-electrolyte interphase (SEI), enabling homogeneous lithium deposition for suppressing dendrite growth. Consequently, the Li-S battery with DPDTe exhibits remarkable cycling stability and superb rate capability, with a high capacity up to 1227.3 mAh g(-1) and stable cycling over 300 cycles. Moreover, a Li-S pouch cell with DPDTe is evaluated as the proof of concept. This work demonstrates that organotelluride compounds can be used as functional electrolyte additives and offers new insights and opportunities for practical Li-S batteries.

Automated summary

A dual-functional electrolyte additive, diphenyl ditelluride (DPDTe), was reported for lithium-sulfur batteries. It acts as a redox mediator for accelerating the redox kinetics of sulfur and reacts with lithium metal to form a stable solid-electrolyte interphase (SEI). The lithium-sulfur battery with DPDTe shows remarkable cycling stability and high-rate performance.