Enhancing Li-S Battery Performance Through Low-Concentration Electrolytes with Organic Se/Te Co-Additives to Address Solubility and Kinetic Challenges

Lithium–sulfur (Li–S) batteries face low sulfur utilization and limited rate capability. Although electrolyte engineering is a key strategy for improving the conversion kinetics of lithium polysulfides (LiPS), achieving a balance between high energy density and high power density remains challenging. This study combines an ultra-low concentration electrolyte with a dual-functional hybrid organic selenium/organic tellurium additive (DPDSe/DPDTe). The system exhibits higher ionic conductivity and enhanced LiPS conversion kinetics. This is attributed to the high solubility of LiPS at low concentrations, which enhances the accessibility of active materials. By adjusting the mixing ratio of DPDSe/DPDTe, the formed DPDSe-Te exhibits unique solvation structure regulation and synergistic catalytic effects. This Li–S battery delivers an initial specific capacity of 1103 mAh g −1 (65.9% sulfur utilization) at 0.5 C and retains 89.3% of its capacity after 100 cycles. Even at 2 C, a capacity of 783 mAh g −1 is achieved. The pouch cell exhibits a high energy density of 340 Wh kg −1 at 0.5 C with stable cycling. This low-concentration, dual-functional additive strategy synergistically addresses LiPS solubility limitations and kinetic bottlenecks, offering an effective route toward Li–S batteries with both high energy density and high-power density.