Enhancing Adsorption and Reaction Kinetics of Polysulfides Using CoP-Coated N-Doped Mesoporous Carbon for High-Energy-Density Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur (Li-S) batteries have shown great potential in the next-generation energy storage devices due to high theoretical energy density and low cost. To obtain high-performance Li-S batteries, it is important to inhibit the polysulfide shuttle effect and improve the reaction kinetics of polysulfides. Herein, CoP nanoparticles coated by metal-organic framework-derived N-doped mesoporous carbon (CoP@N-C) composites are synthesized and applied in both a cathode for a sulfur host and a modified layer on a separator for high-energy-density Li-S batteries since the CoP component has strong chemical anchoring capability toward soluble polysulfides and high electrochemical activity toward polysulfides transformation. Meanwhile, the porous structure of conductive N-doped mesoporous carbon can not only buffer the volume variation of sulfur during the charge/discharge process but also enhance the charge transport rate in the cathode. The constructed batteries have demonstrated a high specific capacity of 1222 mAh g-1 (8.6 mAh cm-2) with a high sulfur areal loading of ∼7.0 mg cm-2 on cathodes, and a mass loading of 0.35 mg cm-2 for modified layer on separators. Its average capacity decay is only 0.076% per cycle after 100 cycles. This work presents the highly competitive performance of Li-S batteries on the areal capacity and capacity decay.