Nitrogen-doped ordered multi-hollow layered carbon embedded with Mo2C as lithium polysulfide restrained cathode for Li-S batteries

Abstract

Practical applications of lithium-sulfur (Li-S) batteries are constrained due to the poor electrical conductivity of sulfur, the shuttle effect, and the volume expansion during the cycle. In this study, N-doped ordered multi-hollow layered carbon embedded with Mo2C is successfully prepared (Mo2C@NC-NaCl) under the co-regulation of dicyandiamide and sodium chloride on the carbon material. In the carbon material, the multi-hollow layered carbon skeleton derived from biomass acts as an advanced sulfur host, which can accelerate electron transportation and buffer volume changes. The synergistic effect of Mo2C nanoparticles and pyridine N anchors lithium polysulfides and realizes fast sulfur electrochemistry. Benefiting from the above advantages, Mo2C@NC-NaCl with a sulfur loading of 2.5 mg cm−2 delivers a high initial discharge specific capacity of 1226.2 mAh g−1 at 0.2 C. Even at a high rate of 1 C, the battery still achieves an initial capacity of 853.7 mAh g−1 and the average capacity decay rate per cycle is 0.065% over 500 cycles. It is expected this work provides a new perspective for large-scale production of cathode materials for Li-S batteries.