Synergistic Pyridinic N/Pyrrolic N configurations in rGO/CNT composite sulfur hosts for high-performance lithium-sulfur batteries

Significant progress has been made in the field of nitrogen-doped carbon sulfur host materials to address the shuttle effect, expansion effect, and conductivity issues of lithium-sulfur (Li-S) battery cathode materials. However, there has been limited study on the synergistic effects of different nitrogen configurations. In this work, ammonia and hydrazine hydrate were used as nitrogen source precursors to prepare three kinds of rGO and CNT composite sulfur hosts with different nitrogen configurations. Ammonia is conducive to the formation of Pyrrolic N, while hydrazine hydrate is conducive to the formation of Pyridinic N. Lithium-sulfur batteries assembled with 3NG/CNT/S which has similar Pyridinic N and Pyrrolic N contents, have a specific initial discharge capacity of 1345 mAh/g at 0.2 C. The initial discharge specific capacity at 2 C was 819 mAh/g, and after 400 cycles, the remaining capacity is 667 mAh/g. The synergistic impact mechanism of Pyridinic N/Pyrrolic N configurations was further revealed by first principles calculations. The results indicate that Pyridinic N/Pyrrolic N configurations enhance electronic non-locality, significantly improve the reactivity of carbon materials, reduce the Gibbs free energy during polysulfide reactions, and accelerate the reaction rate.