Strong internal electric field enhanced polysulfide trapping and ameliorates redox kinetics for lithium-sulfur battery

Abstract

The shuttle effect of polysulfides is a major challenge for the commercialization of lithium-sulfur battery. The systematic modification of separators has the potential to solve these problems by enhancing the adsorption and catalytic conversion of polysulfides. Herein, strong internal electric field bismuth oxycarbonate (Bi2O2CO3) nanoflowers decorated conductive carbon (DC + BOC) is proposed to be systematically modified on separator. This intermediate layer not only possesses a strong affinity for polysulfides, but also promotes the conversion of polysulfides and induces the formation of a stable solid electrolyte interphase (SEI) layer, thereby improving the rate performance and cycling stability of the battery. As expected, the modified membrane achieved a high specific capacity of 713 mA h g−1 at 5 C. At 1 C, high reversibility of 719 mA h g−1 was achieved after 550 cycles with only 0.044% decay per cycle. More importantly, under the sulfur loading of 5.1 mg cm−2, the area specific capacity remained at 4.1 mA h cm−2 after 200 cycles, and the attenuation rate per cycle was only 0.056%. This work provides a new strategy to overcome the shuttle effect of polysulfide, and shows great potential in the application of high-performance lithium-sulfur batteries.