Enhanced polysulfide conversion catalysis in lithium-sulfur batteries with surface cleaning electrolyte additives

The catalysis of polysulfide conversion reactions is a recent approach to improve the performance and durability of Li-S batteries. While conventional wisdom emphasizes on the search for better catalysts, very few studies have considered the effect of S/Li2S2/Li2S solid deposition on the catalyst surface during battery operation. The accumulation of S/Li2S2/Li2S solid deposits on the catalyst surface can lead to progressive catalyst deactivation. This study shows how solid deposition can be minimized by tuning the electrolyte with electrolyte additives for a more sustained catalysis of the polysulfide conversion reactions. Specifically, a toluene and phosphorus pentasulfide-modified electrolyte is used to sweep the solid deposits from catalyst surface, so that the catalyst surface can be refreshed throughout the battery charge-discharge process. The surface rejuvenation effect was applied to further improve a newly developed high performance bimetallic Fe-N and Co-N co-doped carbon polysulfide catalyst; enabling sulfur cathodes with very high initial sulfur utilization (94%) and long cycle stability (2000 cycles with 67% capacity retention at 2C).

Automated summary

The research focuses on minimizing solid deposition by tuning the electrolyte additives to achieve sustained catalytic effects on polysulfide conversion reactions. The use of toluene and phosphorus pentasulfide-modified electrolyte helps to sweep solid deposits from the catalyst surface, enabling surface rejuvenation throughout the battery charge-discharge process. This approach is applied to improve a newly developed high performance bimetallic Fe-N and Co-N co-doped carbon polysulfide catalyst, leading to high initial sulfur utilization and long cycle stability in sulfur cathodes.