Copper-Stabilized Sulfur-Microporous Carbon Cathodes for Li–S Batteries

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Abstract

A copper-stabilized sulfur-microporous carbon (MC-Cu-S) composite is synthesized by uniformly dispersing 10% highly electronically conductive Cu nanoparticles into microporous carbon (MC), followed by wet-impregnating S. In the MC-Cu-S composite, the MC host that physically confines S/polysulfides provides free space to accommodate volumetric expansion of S during lithiation, while the Cu nanoparticles that are anchored in the MC further chemically interact with S/polysulfides through bonding between Cu and S/polysulfides. The Cu loading allows the S content to increase from 30 to 50% in the carbon-S cathode material without scarifying the electrochemical performance in a low-cost carbonate electrolyte. At a current density of 100 mA g-1, the MC-Cu-S cathode shows that Coulumbic efficiency is close to 100% and capacity maintains more than 600 mAh g-1 with progressive cycling up to more than 500 cycles. In addition, the Cu nano-inclusins also enhance the electronic conductivity of the MC-Cu-S composite, remarkably increasing the rate capabilities. Even the current density increases 10.0 A g-1, the MC-Cu-S cathode can still deliver a capacity of 200 mAh g-1. This strategy of stabilization of S with small amount of metal nanoparticles anchored in MC provides an effective approach to improve the cycling stability, Coulumbic efficiency, and S loading for Li–S batteries.

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