Lithium Tritelluride as an Electrolyte Additive for Stabilizing Lithium Deposition and Enhancing Sulfur Utilization in Anode-Free Lithium–Sulfur Batteries

Despite the potential to become the next-generation energy storage technology, practical lithium–sulfur (Li–S) batteries are still plagued by the poor cyclability of the lithium-metal anode and sluggish conversion kinetics of S species. In this study, lithium tritelluride (LiTe₃), synthesized with a simple one-step process, is introduced as a novel electrolyte additive for Li–S batteries. LiTe₃ quickly reacts with lithium polysulfides and functions as a redox mediator to greatly improve the cathode kinetics and the utilization of active materials in the cathode. Moreover, the formation of a Li₂TeS₃/Li₂Te-enriched interphase layer on the anode surface enhances ionic transport and stabilizes Li deposition. By regulating the chemistry on both the anode and cathode sides, this additive enables a stable operation of anode-free Li–S batteries with only 0.1 m concentration in conventional ether-based electrolytes. The cell with the LiTe₃ additive retains 71% of the initial capacity after 100 cycles, while the control cell retains only 23%. More importantly, with high utilization of Te, the additive enables significantly better cyclability of anode-free pouch full-cells under lean electrolyte conditions.