Modulating d-Band Electronic Structures of Molybdenum Disulfide via p/n Doping to Boost Polysulfide Conversion in Lithium-Sulfur Batteries

Abstract

Polysulfide shuttle effect and sluggish sulfur reaction kinetics severely impede the cycling stability and sulfur utilization of lithium-sulfur (Li-S) batteries. Modulating d-band electronic structures of molybdenum disulfide electrocatalysts via p/n doping is promising to boost polysulfide conversion and suppress polysulfide migration in lithium-sulfur batteries. Herein, p-type V-doped MoS2 (V-MoS2) and n-type Mn-doped MoS2 (Mn-MoS2) catalysts are well-designed. Experimental results and theoretical analyses reveal that both of them significantly increase the binding energy of polysulfides on the catalysts’ surface and accelerate the sluggish conversion kinetics of sulfur species. Particularly, the p-type V-MoS2 catalyst exhibits a more obvious bidirectional catalytic effect. Electronic structure analysis further demonstrates that the superior anchoring and electrocatalytic activities are originated from the upward shift of the d-band center and the optimized electronic structure induced by duplex metal coupling. As a result, the Li-S batteries with V-MoS2 modified separator exhibit a high initial capacity of 1607.2 mAh g−1 at 0.2 C and excellent rate and cycling performance. Moreover, even at a high sulfur loading of 6.84 mg cm−2, a favorable initial areal capacity of 8.98 mAh cm−2 is achieved at 0.1 C. This work may bring widespread attention to atomic engineering in catalyst design for high-performance Li-S batteries.