Synergistic mechanisms of nitrogen configurations in sulfur hosts and their enhancement of electrochemical performance in lithium‑sulfur batteries

Abstract

Lithium‑sulfur batteries (LSBs) have attracted a lot of attention due to their high theoretical capacity and energy density. However, the cathode material for LSBs is limited by the low conductivity of sulfur and its products, as well as volume fluctuations during charging and discharging, and the shuttle effect of soluble lithium polysulfide. In this work, a cathode sulfur host material Nitrogen-doped porous carbon materials (N-PCM) was synthesized, doped with Pyridine N and Pyrrolic N, using melamine and glycine as nitrogen sources, silicon dioxide as template. The synthesis method characterized by controllable nitrogen content and nitrogen configurations. The results of the electrochemical performance test indicate that the composite N-PCM/S exhibits a higher capacity and enhanced cycling stability. At a rate of 0.1C, N-PCM/S demonstrates an initial discharge capacity of up to 1308 mAh/g. At 2C, the initial discharge capacity is 603 mAh/g, while maintaining a reversible capacity of 543 mAh/g after 400 cycles. The capacity decay rate is only 0.025 % per cycle, showcasing excellent cycle stability. Additionally, the N-PCM/S exhibits excellent electrochemical performance under electrolyte-poor conditions. The results showed that the synergistic effect of different nitrogen configurations significantly enhanced the adsorption and catalytic conversion of polysulfide by sulfur hosts, accelerate the reaction rate of polysulfide.