Impact of Sulfur Infiltration Time and Its Content in an N-doped Mesoporous Carbon for Application in Li-S Batteries

Li-S batteries are ideal candidates to replace current lithium-ion batteries as next-generation energy storage systems thanks to their high specific capacity and theoretical energy density. Composite electrodes based on carbon microstructures are often used as a host for sulfur. However, sulfur lixiviation, insoluble species formation, and how to maximize the sulfur-carbon contact in looking for improved electrochemical performance are still major challenges. In this study, a nitrogen doped mesoporous carbon is used as a host for sulfur. The S/C composite electrodes are prepared by sulfur melting-diffusion process at 155 °C. The effect of the sulfur melting-diffusion time [sulfur infiltration time] (1–24 h) and sulfur content (10–70%) is investigated by using XRD, SEM, TEM and TGA analyses and correlated with the electrochemical performance in Li-S cells. S/C composite electrode with homogeneous sulfur distribution can be reached with 6 h of sulfur melting-diffusion and 10 wt.% of sulfur content. Li-S cell with this composite shows a high use of sulfur and sufficient electronic conductivity achieving an initial discharge capacity of 983 mA h g−1 and Coulombic efficiency of 99% after 100 cycles.