Chemo‑Electrochemical Tandem Catalysis Unlocking Sulfur Reaction in Practical Lithium–Sulfur Batteries

ABSTRACT As next‐generation high‐energy batteries, lithium–sulfur (Li–S) batteries are promising solutions for long‐range electric vehicles due to their ultrahigh theoretical energy density. However, they face fundamental challenges from low sulfur utilization, particularly under electrolyte‐starved practical conditions that polysulfides are unable to dissolve. Here, we propose a chemo‐electrochemical tandem catalyst, Li x TiS 2 , which chemically catalyzes the transformation of S 8 /Li 2 S 8 to Li 2 S 4 and subsequently catalyzes electrochemical reduction to lithium sulfide (Li 2 S). This tandem mechanism fundamentally alters the reaction kinetics from conventional first‐order to zero‐order behavior, overcoming the limitation imposed by the solubility of sulfur species. It thus enables efficient sulfur conversion and an ultralow activation energy of ∼0.3 eV (a 50% reduction compared to without catalysts) under a low electrolyte‐to‐sulfur (E/S) ratio (5 µL mg s −1 ), significantly improving battery performance in practical conditions. The coin cell shows an ultralow capacity decay of 0.028% per cycle over 1500 cycles, and a 2.0 Ah pouch cell achieves the high energy density of 550 Wh kg −1 with good stability.