Dual-functional chloropyrazine additives for enhanced performance of lithium-sulfur batteries

The commercialization of lithium-sulfur batteries (LSBs) faces challenges due to uncontrolled lithium deposition and lithium polysulfides (LiPSs) shuttling. In this study, a class of chloropyrazine-based electrolyte additives was introduced to address these issues. The results showed that the presence of chloropyrazine facilitated the formation of a robust and smooth organic-inorganic hybrid solid-electrolyte interface (SEI) enriched with LiCl. This SEI layer enabled reversible lithium plating/stripping, suppressed dendrite growth, and protected the lithium anode from detrimental side reactions with LiPSs. Furthermore, Density functional theory (DFT) results demonstrate that chloropyrazine additives effectively modulated the molecular orbital energy levels of LiPSs and promoted the kinetics of their conversion reactions. LSBs incorporating chloropyrazine additives demonstrated outstanding high-rate performance and long-term cycling stability, with over 800 cycles at 1 C rate and a capacity retention of 81.6 %. Even under challenging conditions of high sulfur loading (5.8 mg cm⁻²) and low electrolyte-to-sulfur ratio (5 μL mg⁻¹), the battery demonstrated capacity decay rate of only 0.066 % per cycle after 500 cycles at 0.2 C rate. With the highlights of dual-functional chloropyrazine electrolyte additives in improving interfacial chemistry and modulating the orbital energy levels of LiPSs, this work offers a promising direction for advanced electrolyte design in LSBs.