Bimetallic Ni-Mo_<i>x</i>C Heterojunctions as Bidirectional Electrocatalysts Synergistically Accelerate Sulfur Conversion Kinetics in Li–S Batteries

Lithium–sulfur batteries (LSBs) are promising contenders for next-generation energy storage systems due to their high theoretical specific capacity. However, the severe shuttle effect of soluble lithium polysulfides (LiPSs) hinders the further development of LSBs. In this work, a rod-like Ni-MoxC heterojunction as a functional separator is synthesized via hydrothermal and calcination methods for LSBs. Ni doping not only increases the specific surface area and catalytic adsorption active sites of Ni-MoxC heterojunctions but also accelerates the ion transport efficiency by forming a built-in electric field. In addition, the synergistic interaction between Ni and MoxC enhances the electrocatalytic activity and promotes the bidirectional catalysis of LiPSs. As a result, the cell with a Ni-MoxC separator has an excellent initial specific capacity of 936.8 mAh g–1 at a high current density of 3 C, with a capacity decay rate of only 0.097% after 400 cycles. A high area capacity of 6.9 mAh cm–2 is obtained at a S load condition of 5.90 mg cm–2. This work provides an effective strategy for the fabrication of heterostructured materials that effectively suppresses the shuttle effect through the synergistic effect of adsorption and catalysis.