Atomic substitution engineering-induced domino synergistic catalysis in Li-S batteries

Atomic substitution engineering is considered as effective strategy to activate the basal plane of molybdenum disulfide (MoS2) which has been demonstrated effective catalytic cathode in lithium-sulfur (Li-S) batteries. Rationally designing atomic substitution structure is vital to figure out the origin of catalytic activity in dopedMoS2 based catalytic cathodes. Herein, an "adjacent period, adjacent group" atomic substitution engineering is constructed to investigate the role of foreign atoms in sulfur redox reaction, and reveal the origin of catalytic activity. Theoretical calculations reveal that the real active sites are the S atoms adjacent to the doped atoms. It has been demonstrated that Nb atomic substitution acts as an initiator to trigger a "Domino Effect" of activating the S sites, enhancing the adsorption ability, facilitating the conversion reaction of sulfur species, and accelerating the Li+ diffusion. Enlightened by the theoretical guidance, Nb-doped MoS2 ultrathin nanosheets assembled hollow nanotubes (Mo1-xNbxS2 HNTs) are fabricated as efficient "adsorption-conversion" sulfur hosts, which exhibit high initial discharge capacities (1163 mAh g- 1 at 0.2 C, 971 mAh g- 1 at 0.5 C). An initial capacity of 613 mAh g- 1 could be achieved under high sulfur loading (3.13 mg cm- 2) and lean electrolyte (5.6 mu L mg- 1). This work provides pivotal guidance to design highly efficient catalytic cathodes for advanced Li-S batteries.