Rich Heterointerfaces Enabling Rapid Polysulfides Conversion and Regulated Li₂S Deposition for High-Performance Lithium-Sulfur Batteries.

Abstract

The practical uses of lithium-sulfur batteries are greatly restricted by the sluggish reaction kinetics of lithium polysulfides (LiPSs), leading to low sulfur utilization and poor cyclic stability. Using the heterostructure catalysts is an effective way to solve the above problems, but how to further enhance the conversion efficiency and avoid the surface passivation by the insulative Li₂S has not been well investigated. Herein, a heterostructure catalyst with rich heterointerfaces was prepared by modifying Mo₂N microbelt with SnO₂ nanodots. The formed rich interfaces with high accessibility act as the profitable nucleation sites guiding the Li₂S 3D growth, which avoids the catalyst surface passivation and facilitates the LiPS conversion. The introduction of SnO₂ nanodots also enhances the LiPS adsorption. Thus, the assembled battery with the above catalyst as the cathode additive shows a high capacity of 738.3 mAh g^-1 after 550 cycles at 0.5 C with an ultralow capacity decay of 0.025% per cycle. Even with high sulfur loading of 9.0 mg cm^-2, good cyclic stability is also achieved at 0.5 C with a low <i>E</i>/<i>S</i> ratio of 5 μL mg_s^-1. This work shows an effective way to enhance the LiPS conversion kinetics and guide Li₂S deposition in Li-S batteries.