Regulated Li₂S Deposition through Evolution of Silver Chloride for Li-S Batteries

Lithium-sulfur (Li-S) batteries hold great promise as a next-generation energy storage system due to their high theoretical energy density (2600 W h kg^-1), surpassing conventional lithium-ion batteries. However, their performance is often limited by the intrinsic transformation of soluble lithium polysulfides (LiPSs) into short-chain insoluble sulfur species (Li₂S₂/Li₂S), which induces significant cell polarization, particularly under lean-electrolyte conditions. Through a galvanic replacement reaction (GRR), enabling precise tailoring of interfacial properties, AgCl-PVP nanocubes (NCs) were synthesized and utilized as sulfur host materials. These materials demonstrated effective entrapment of LiPSs, as confirmed by in situ electrochemical visualization. Furthermore, the AgCl-PVP NCs significantly reduced whole-cell polarization, particularly during the Li₂S nucleation step, as validated by galvanostatic intermittent titration technique across the depth of discharge. Under lean-electrolyte conditions (5.6 μL mg^-1), the AgCl-PVP NCs cathode exhibited high specific capacity (563.62 mA h g^-1 at 0.2 C) with a low-capacity decay rate (1.81% per cycle). These results demonstrate the potential of GRR-engineered nanostructures as sulfur host material for enhancing the electrochemical performance and practical applicability of lean-electrolyte Li-S batteries.