Molecular Clip Strategy of Modified Sulfur Cathodes for High-Performance Potassium Sulfur Batteries.

Potassium-sulfur (K-S) batteries are severely limited by the sluggish reaction kinetics of the cyclooctasulfur (cyclo-S) electrode with low conductivity, which urgently requires a novel cathode to facilitate activity to improve sulfur utilization. In this study, using the wet chemistry method, the molecular clip of Li is created to replace cyclo-S molecular with the highly active chain-like S molecular. The molecular clip strategy effectively lowers the reaction barrier in potassium-sulfur systems, and the stretching of S─S bonds weakens the binding between sulfur atoms, facilitating the transformation of potassium polysulfides (KPSs). The as-prepared cathode exhibits a reversible capacity of 894.8 mAh g at a current rate of 0.5 C. It maintains a long cycle life of 1000 cycles with a stable coulombic efficiency in the potassium-sulfur cells without cathode catalysts. Operando XRD and Raman spectra combined with density functional theory (DFT) calculations, revealing the high efficiency of enhanced conversion of potassium polysulfide for high-performance K-S batteries.