Bifunctional Mo2C–N Sites on a Mo2C-GO-NC Interlayer for High-Performance Lithium–Sulfur Batteries: Suppressing the Shuttle Effect and Enhancing Kinetics

The commercialization of lithium–sulfur (Li–S) batteries faces significant challenges due to the shuttle effect of lithium polysulfides and sluggish reaction kinetics. To address these issues, a Mo2C-GO-NC interlayer, decorated with bifunctional Mo2C–N binding sites, is successfully synthesized via a facile one-step complexation method. The combination of transition metal molybdenum and nitrogen doping endows the reduced graphene oxide with a unique porous structure, strong chemisorption capabilities, and exceptional catalytic conversion properties. The Mo2C-GO-NC interlayer effectively traps lithium polysulfides and accelerates their conversion, as confirmed by theoretical calculations and in situ Raman spectroscopy. These studies reveal that the bifunctional Mo2C–N sites promote uniform Li2S deposition and enhance Li+ migration, significantly improving the reaction kinetics. As a result, the Li–S cells assembled by the Mo2C-GO-NC-modified separator exhibit a high initial capacity of 906.1 mAh g–1 at 1 C with a capacity decay rate of only 0.032% per cycle. In addition, a discharge capacity of 832.2 mAh g–1 was still exhibited after 110 cycles at a high sulfur loading of 5 mg cm–2. This work offers a strategic approach for designing advanced interlayers with bifunctional binding sites, paving the way for high-performance Li–S batteries.