Deep Eutectic Electrolyte Induces S ₃ ⁻ Radicals to Enhance Reaction Kinetics for Solid‐State Lithium‐Sulfur Batteries

Abstract Solid‐state lithium‐sulfur batteries (SSLSBs) hold immense promise for next‐generation energy storage due to their high energy density and enhanced safety. However, their practical application is hindered by sluggish reaction kinetics and poor reversibility of the sulfur cathode. This work introduces a multifunctional catholyte interlayer capable of inducing the generation of highly active S ₃ ^•− radical: a carbon nanotube (CNTs) coating supporting TiN nanoparticles, infiltrated with a 1,2‐dimethylimidazole (DMIm) based deep eutectic electrolyte (DEE). The flexible CNTs matrix ensures tight contact between the sulfur cathode and the solid‐state electrolyte (SSE), facilitating efficient charge transport. TiN nanoparticles strongly adsorb lithium polysulfides (LiPSs). Crucially, the highly polar DEE promotes the generation and stabilization of S ₃ ^•− radical intermediates, providing additional reaction pathways, thereby improving sulfur utilization and accelerating kinetics. Consequently, the SSLSBs achieve stable operation for over 1300 cycles at 0.2 C and maintain a high capacity of 929.7 mAh g ⁻¹ at 1.5 C. This work provides an effective strategy for strengthening the SSE/sulfur cathode interface and accelerating reaction kinetics in SSLSBs.