Synergistic Dual Modulation of Li ₂ S Redox Kinetics and Anode Stability Enabled by a High‐Efficiency Organodisulfide Mediator in Anode‐Free Lithium–Sulfur Batteries

Abstract

ABSTRACT Lithium sulfide (Li 2 S) is pivotal for high‐energy‐density lithium–sulfur (Li─S) batteries due to its high theoretical capacity, abundant sulfur resources, and compatibility with anode‐free architectures. However, its application is hindered by its intrinsically insulating nature and sluggish redox kinetics. Furthermore, traditional 1,3‐dioxolane/1,2‐dimethoxyethane electrolytes cannot withstand high voltages and pose safety hazards due to low flash points. Herein, we propose a synergistic strategy by introducing diisopropyl dithiocarbonate disulfide (DIP) as a multifunctional redox mediator into a high‐flash‐point, high‐voltage‐tolerant tetraethylene glycol dimethyl ether electrolyte system. DIP directly converts Li 2 S to lithium polysulfides, decreasing the activation voltage of the first charge to 2.48 from 3.18 V. Simultaneously, DIP facilitates the formation of an organosulfur‐rich solid electrolyte interface on the lithium surface, effectively suppressing lithium dendrite formation and growth. Crucially, this system enables stable cycling in anode‐free Cu||Li 2 S batteries for 160 cycles at 0.3 mAh cm −2 . Standard Li||Li 2 S cells also demonstrate superior durability, achieving an extremely low per‐cycle decay rate of 0.037% at 1C. Moreover, this strategy holds promise for other metal‐sulfur systems, such as Na─S, K─S, Ca─S, Mg─S, and Zn─S batteries, providing a feasible path for safe, next‐generation energy storage.