Two types of nitrogen and sulfur co-doped carbons derived from soybean sprouts enabling high performance lithium‑sulfur batteries

Abstract

Lithium sulfur batteries (LiSBs) are regarded as the promising energy storage technologies because of its high energy density and theoretical capacity, rich sulfur cathode resources, low price and environmental friendliness. However, the utilization rate of sulfur is low and the capacity attenuation is fast due to the insulativity of sulfur, volume expansion/contraction and shuttle effect during charging and discharging, which seriously hinders its commercialization process. In this work, two types of nitrogen and sulfur co-doped carbons were designed and prepared by separating the roots and cotyledons of soybean sprouts. The as-prepared co-doped carbons were used as a coating on the commercial separator. The coated separator can not only physically adsorb polysulfides, but also increase the chemical adsorption of polysulfides due to the introduction of active sites by co-doping, so it can effectively inhibit the shuttle effect. The first discharge capacities of LiS batteries with NS-SSRC and NS-SSCC coated separators at 1C were 847.7 mAh g−1 and 888.1 mAh g−1, respectively, and they retained 389.7 mAh g−1 and 477.6 mAh g−1 after 500 cycles, respectively.