Boosting polysulfides conversion kinetics through heterostructure optimization and electrons redistribution for robust lithium-sulfur batteries

Abstract

Lithium-sulfur batteries (LSBs) are gaining significant attention as a promising candidate to satisfy the demand for high energy density. However, their application is still hindered by the notorious shuttle effect of intermediate polysulfides and the sluggish redox kinetics. Herein, we provide an electrocatalyst composed of two-dimensional (2D) bimetallic sulfides with layered cross-linking structure evenly distributed on 2D MXene nanosheets substrates (Bi2S3/MoS2@MX). Composition optimization and rational structural design effectively mitigate the self-stacking defect and expand the exposure of active sites. The electrons redistribution at heterogeneous interfaces generates a built-in electric field, thereby promoting electron transfer efficiency. Experiments and theoretical calculations results confirmed that the synergistic effect of heterostructures can effectively strengthen the adsorption and conversion of polysulfides, thereby significantly mitigating the shuttle effect. The utilization of sulfur is improved, and the corrosion degree of lithium metal anode is reduced. Consequently, the LSBs assembled with Bi2S3/MoS2@MX modified separator manifest an impressive initial specific capacity of 1306 mAh g−1 at 0.2C. Remarkably, the battery exhibits good long-term cycling stability with only 0.069 % capacity degradation per cycle at 2C after 500 cycles. This work demonstrates that synergistic cooperation of diverse catalytic materials represents an effective strategy for enhancing the potential for industrial application of LSBs.