Rational design of hollow flower-like MoS2/Mo2C heterostructures in N-doped carbon substrate for synergistically accelerating adsorption-electrocatalysis of polysulfides in lithium sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have been garnered significant attention in the energy storage field due to their high theoretical specific capacity and low cost. However, Li–S batteries suffer from issues like the shuttle effect, poor conductivity, and sluggish chemical reaction kinetics, which hinder their practical development. Herein, a novel hollow flower-like architecture composed of MoS2/Mo2C heterostructures in N-doped carbon substrate (H-Mo2S/Mo2C/NC NFs), which were well designed and prepared through a calcination-vulcanization method, were used as high-efficiency catalyst to propel polysulfide redox kinetics. Ex situ electrochemical impedance spectroscopy verify that the abundant heterojunctions could facilitate electron and ion transfer, revealed the excellent interface solid–liquid–solid conversion reaction. The adsorption test of Li2S6 showed that Mo2S and Mo2C formed heterostructure generate the binding of polysulfide could be enhanced. And cyclic voltammetry test indicate boost the polysulfide redox reaction kinetics and ion transfer of H-Mo2S/Mo2C/NC/S NFs cathode. Benefiting from the state-of-the-art design, the H-Mo2S/Mo2C/NC/S NFs cathode demonstrates remarkable rate performance with a specific capacity of 1351.9 mAh g−1 at 0.2 C, when the current density was elevated to 2 C and subsequently reverted to 0.2 C, the H-Mo2S/Mo2C/NC/S NFs cathode retained a capacity of 1150.4 mAh g−1, and it maintains exceptional long cycling stability (840 mA h g−1 at 2 C after 500 cycles) a low capacity decay of 0.0073% per cycle. This work presents an effective approach to rapidly fabricating multifunctional heterostructures as an effective sulfur host in improving the polysulfide redox kinetics for lithium sulfur batteries.