Dual Single-Atom Moieties Anchored on N-Doped Multilayer Graphene As a Catalytic Host for Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur (Li-S) batteries are promising for energy storage, especially in the era of carbon neutrality. Nonetheless, the sluggish kinetics of converting soluble lithium polysulfides into solid lithium sulfide impedes its development. In this work, we design Fe and Co dual single-atom moieties anchored on N-doped multilayer graphene (FeCoNGr) as a catalytic sulfur cathode host for Li-S batteries. With an efficient catalytic role in converting soluble lithium polysulfides into solid Li2S, the FeCoNGr-based Li-S cell demonstrates a capacity of 878.7 mA h g-1 at 0.2 C and retains 77.4% of the initial value after 100 cycles. The first and retained capacities are ∼1.7 and ∼1.8 times those of the NGr (without single atoms)-based cell, respectively. Theoretical calculations reveal that the Fe-N4 moiety has a higher binding energy toward low-order lithium polysulfides, while the Co-N4 moiety has a higher binding energy toward high-order lithium polysulfides. The efficient catalytic conversion of soluble lithium polysulfides into solid lithium sulfides of FeCoNGr plays important roles in outperforming NGr. This work enhances our knowledge on the tandem role of dual single-atom moieties and confirmed the high catalytic efficiency of single-atom catalysts in Li-S batteries.