Ethylenediamine functionalized graphene wrapped nano-sulfur structures enhances the performance of Li-S batteries with high sulfur loading

Commercial applications of lithium-sulfur batteries (LSBs) suffer from low sulfur utilization, inadequate cell capacity, and inefficient cycling stability, especially under conditions of poor electrolyte and high sulfur loading. Herein, strategies to load sulfur within the wrapped have been proposed, where the large volume expansion and polysulfide diffusion problems can be suppressed. Simultaneously, maximizing sulfur loading is realized. Nanosulfur@N-modified graphene oxide (S@EGO) wrapped structures were synthesized by electrostatic adsorption method. The sulfur core was formed by the recrystallization, and the graphene oxide shell was decorated with a trace amount of reducing agent ethylenediamine (EDA). The resulting wrapped particle size is 3 - 5 mu m, including 20 - 50 nm nano-sulfur particle size. N-doped GO (EGO) under suitable temperatures (85 degrees C) exhibits perfect wrapped state and catalytic activity which gives rise to superior battery performances: the dischargespecific capacity decayed from 1010 mAh/g to 440 mAh/g (900 cycles at 1 C) with an average capacity decay rate of 0.0627 % per cycle. Thermogravimetric analysis that the material prepared by this method reached a sulfur loading of 92 wt%, showing a high prospect of application.