Mo2N Quantum Dots Decorated N-doped Graphene Nanosheets as Dual-Functional Interlayer for Dendrite-Free and Shuttle-Free Lithium-Sulfur Batteries

The industrialization of lithium-sulfur (Li-S) batteries is simultaneously impeded by the shuttle effect of lithium polysulfides and dendrites growth on lithium anode. To address both issues, a novel sulfiphilic and lithiophilic interlayer of Mo2N quantum dots decorated N-doped graphene-nanosheet (Mo2N@NG) are presented on polypropylene separator via a facile scalable method. Benefiting from the strong chemisorption ability, eminent electrocatalysis for LiPSs, and high chemical affinity with lithium-ion (Li+), Mo2N@NG can efficiently catalyze the rapid transformation of LiPSs and induce uniform deposition of Li+. Theoretical calculation and in situ Raman synergistically elucidate the inhibition of shuttle effect and alleviation of dendrite growth. As a result, the assembled Li-S cell with Mo2N@NG/PP separator exhibits remarkable rate performance (860.2 mA h g(-1) at 4 C), good cycling stability (0.039% capacity decay per cycle after 800 cycles at 2 C), a high areal capacity of 3.89 mA h cm(-2) of Li-S pouch cell (4.5 mg cm(-2) and 6 mu L mg(-1) at 0.2 C), and steady performance in protecting the lithium anode (at 5 mA cm(-2) for 1500 h). This present strategy of quantum dots in a hybrid framework has great potential to be generalized to other transition metal-based catalysts for advanced Li-S batteries.