Spatially structured lamellar porous Carbon-CoS₂ separator for Enhanced adsorption and conversion of lithium polysulfides in High-Performance Li-S batteries

The shuttle effect of lithium polysulfides (LiPSs) is recognized as the primary factor leading to the capacity fade in lithium-sulfur (Li-S) batteries. In this work, spatially structured lamellar porous carbon (LPC) / transition metal sulfide composites were prepared to modify the separator to enhance the performance of the Li-S battery. The resulting battery, incorporating CoS₂ and LPC (denoted LPC-CoS₂), demonstrates an outstanding specific capacity of 493 mAh·g⁻¹ at an ultra-high current density of 10 C. At a sulfur loading of 6.3 mg·cm⁻², the battery maintains a specific capacity of 885 mAh·g⁻¹ after 200 cycles at 1 mA·cm⁻². The unique structure of LPC provides a physical constraint on LiPSs, preventing the corrosion of the lithium metal anode, and ensuring the uniform deposition of Li⁺. The density functional theory calculations and the experiments proved that CoS₂ serves as a Lewis acid catalyst, with favorable adsorption energy for LiPSs, enabling efficient capture of LiPSs and facilitating their transformation through the elongation or cleavage of Li-S and S-S bonds after adsorption. The multifunctional separator modification material with a spatial structure facilitates rapid LiPSs adsorption catalysis and provides effective protection for the lithium anode, offering a novel approach to achieving high-performance practical Li-S batteries.