Lithium Trithiocarbonate as a Dual-Function Electrode Material for High-Performance Lithium-Sulfur Batteries

The development of practical lithium-sulfur (Li-S) batteries with prolonged cycle life and high Coulombic efficiency is limited by both parasitic reactions from dissolved polysulfides and mossy lithium deposition. To address these challenges, here lithium trithiocarbonate (Li2CS3)-coated lithium sulfide (Li2S) is employed as a dual-function cathode material to improve the cycling performance of Li-S batteries. Interestingly, at the cathode, Li2CS3 forms an oligomer-structured layer on the surface to suppress polysulfide shuttle. The presence of Li2CS3 alters the conventional sulfur reaction pathway, which is supported by material characterization and density functional theory calculation. At the anode, a stable in situ solid electrolyte interphase layer with a lower Li-ion diffusion barrier is formed on the Li-metal surface to engender enhanced lithium plating/stripping performance upon cycling. Consequently, the obtained anode-free full cells with Li2CS3 exhibit a superior capacity retention of 51% over 125 cycles, whereas conventional Li2S cells retain only 26%. This study demonstrates that Li2CS3 inclusion is an efficient strategy for designing high-energy-density Li-S batteries with extended cycle life.