Constructing MoS2-SnS heterostructures on N-doped carbon nanosheets for enhanced catalytic conversion of polysulfides in lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have been regarded as potential candidates for next-generation high-performance energy storage systems due to the rich sulfur reserves, nontoxicity, high theoretical capacity, and energy density. However, the Li-S batteries suffer from the slow reaction kinetics and lithium polysulfide (LiPSs) shuttling. To address these issues, a bimetallic sulfide MoS2-SnS heterostructure has been constructed by a salt-template method to modify the separator of Li-S batteries. The 3D porous MoS2-SnS heterostructure on N-doped carbon (MoS2-SnS/NC) can improve the LiPSs adsorption and accelerate the LiPSs conversion and Li2S uniform nucleation/deposition due to its pore structure, polar bond, and built-in electric field at the interface of MoS2 and SnS. Therefore, the prepared MoS2-SnS/NC-PP heterostructure exhibits a high initial capacity (1504.6 mAh g-1), superior rate performance (690.1 mAh g-1 at 4C), and good cycling stability (0.07 % capacity decay rate at 400 cycles at 4C). When the sulfur loading is 3.50 mg cm−2, the Li-S battery delivers a capacity of 635 mAh g-1.