Investigation of S/C composite synthesized by solvent exchange method

Solvent exchange method is proposed for the synthesis of sulfur and S/C composite with uniform morphology. SEM, TEM and BET measurements reveal that through this approach, sulfur can subside together with carbon and then form the S/C composite in which sulfur particle is enclosed within the carbon shell even enter into the pores of Printex XE2 carbon. Comparing with sublimed sulfur, the sulfur or S/C composite deriving from the solvent exchange method all shows greatly improved electrochemical performance. Additionally, the influence of solvent on the electrochemical property of the S/C composite is investigated in terms of cycling tests, cyclic voltammetry and impedance measurements. The results show that the S/C composite sample derived from the ultrasonic solvent exchange method in o-xylene solvent has better electrochemical properties than that prepared in CS2. It delivers a capacity of 1173.9 mAh g−1 in the initial cycle and preserves at 712.5 mAh g−1 after 50 cycles at 200 mA g−1. Furthermore, even at a high current density of 1500 mA g−1, its discharge capacity is well maintained at 529 mAh g−1 after 50 cycles, which is much higher than the capacity of 293.6 mAh g−1 for sublimed sulfur electrode.

► Solvent exchange method is proposed to obtain S/C composite within one-step.
► Using this method it can be easy to control the concentration of sulfur in the composite.
► The S/C composite shows a good capacity performance and rate capability.
► Influence of solvent on electrochemical property of S/C composite is studied.