Anode-free, Lean-Electrolyte Lithium-Sulfur Batteries Enabled by Tellurium-Stabilized Lithium Deposition

For realizing practically viable lithium-sulfur (Li-S) batteries, it is imperative to stabilize Li deposition and improve cyclability while reducing excess Li and electrolyte. We have discovered that introducing tellurium (Te) into the Li-S system as a cathode additive significantly improves the reversibility of Li plating and stripping by forming a tellurized and sulfide-rich solid-electrolyte interphase (SEI) layer on the Li surface. A remarkable improvement in cyclability is demonstrated in anode-free full cells with limited Li inventory and large-area Li-S pouch cells under lean electrolyte conditions. Tellurium reacts with polysulfides to generate soluble polytellurosulfides that migrate to the anode side and form stabilizing lithium thiotellurate and lithium telluride in situ as SEI components. A significant reduction in electrolyte decomposition on the Li surface is also engendered. This work demonstrates Te inclusion as a viable strategy for stabilizing Li deposition and establishes a robust evaluation framework for preserving electrochemical performance under limited Li and limited electrolyte conditions. [Display omitted] •The cycling efficiency of Li-metal anode determines the cycle life of Li-S batteries•7-fold improvement in cyclability is seen by introducing Te at the cathode•In situ generated lithium thiotellurate-based SEI stabilizes Li plating and stripping•The unique SEI improves longevity of high-energy, lean-electrolyte pouch cells In order to maximize the specific energy of lithium-sulfur (Li-S) batteries, the cell must be operated without any excess Li. In such a Li-limited system, the loss of Li inventory is the primary determinant of cycle life. The introduction of tellurium (Te) as an additive in Li-S batteries engenders a unique tellurized and sulfide-rich solid-electrolyte interphase (SEI) comprising lithium thiotellurate (Li2TeS3) on the Li surface. This type of SEI stabilizes Li deposition and ensures deposition of dense Li layers at the anode. This prevents electrolyte decomposition, curtails Li loss, and hence extends cycle life. The anode-free full-cell configuration provides a reliable and robust framework for evaluating the dynamics of Li deposition in conjunction with various cathode systems. Additionally, a class of ternary sulfides similar to Li2TeS3 can be explored as artificial SEI layers to enable the stable operation of energy-dense, anode-free Li batteries. The introduction of Te as a cathode additive in Li-S batte