Tri-sulfur radical trapping in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as a next-generation battery technology owing to their prospects of high capacity and energy density. They, however, suffer from rapid capacity decay due to the shuttling of reaction intermediate species: Li polysulfides (LiPSs). One of the more important and intriguing PSs is the tri-sulfur radical (S center dot 3 ), observed mainly in high-donor number (DN) solvent-based electrolytes. Although this radical has been proposed to be crucial to full active material (AM) utilization, there is currently no direct evidence of the impact of S center dot-3 on cycling stability. To gain more insight into the role of the S center dot-3 , we studied the use of radical traps in low and high DN solvent-based electrolytes by operando Raman spectroscopy. The traps were based on nitrone and iminium cation, and S center dot-3 was indeed successfully trapped in ex situ analysis. However, it was the ionic liquidbased trap, specifically pyridinium, that effectively suppressed S center dot-3 during battery operation. Overall, the PS formation was altered in the presence of the traps and we confirmed the impact of S center dot-3 formation on the Li-S battery redox reactions and show how the trapping correlates with Li-S battery performance. Therefore, stabilization of the S center dot