Boosting Charge Transport and Catalytic Performance in MoS₂ by Zn²⁺ Intercalation Engineering for Lithium-Sulfur Batteries.

Abstract

Transition metal dichalcogenides (TMDs) have been widely studied as catalysts for lithium-sulfur batteries due to their good catalytic properties. However, their poor electronic conductivity leads to slow sulfur reduction reactions. Herein, a simple Zn²⁺ intercalation strategy was proposed to promote the phase transition from semiconducting 2H-phase to metallic 1T-phase of MoS₂. Furthermore, the Zn²⁺ between layers can expand the interlayer spacing of MoS₂ and serve as a charge transfer bridge to promote longitudinal transport along the <i>c</i>-axis of electrons. DFT calculations further prove that Zn-MoS₂ possesses better charge transfer ability and stronger adsorption capacity. At the same time, Zn-MoS₂ exhibits excellent redox electrocatalytic performance for the conversion and decomposition of polysulfides. As expected, the lithium-sulfur battery using Zn_0.12MoS₂-carbon nanofibers (CNFs) as the cathode has high specific capacity (1325 mAh g^-1 at 0.1 C), excellent rate performance (698 mAh g^-1 at 3 C), and outstanding cycle performance (it remains 604 mAh g^-1 after 700 cycles with a decay rate of 0.045% per cycle). This study provides valuable insights for improving electrocatalytic performance of lithium-sulfur batteries.