Enhancing adsorption and catalytic activity of Marigold-like In2S3 in lithium-sulfur batteries by vacancy modification

Abstract

Sulfur has attracted much increasing attention as the cathode material for lithium sulfur (Li-S) batteries owing to its high theoretical capacity and energy density. Unfortunately, the shuttling behavior and sluggish conversion kinetics of the intermediate polysulfide as the main obstructions limit to the practical application of Li-S batteries. To address these issues, we prepared marigold-like In2S3/rGO composites with rich sulfur vacancies (In2S3-x/rGO) via a simple hydrothermal method to improve the shuttling and sluggish reaction kinetics of polysulfide in Li-S batteries. The sulfur vacancies can adjust the surface or interface electronic structure of the In2S3 accelerate electron/ion transport, and promote the formation of thiosulfate and polythionate which can adsorb polysulfide more strongly than normal sulfide sites and assist in their transformation to Li2S. These sulfur vacancies in marigold-like In2S3 can promote the catalytic conversion of intercepted polysulfide and prevent them from accumulating on the cathode surface. Attributed to the synergistic effect of structural design and sulfur vacancies fabrication, the Li-S batteries with In2S3-x/rGO exhibited an initial discharge capacity of 1202 mAh g−1 at 0.5C, and offered a reversible capacity of 534 mAh g−1 after 450 cycles at 2C. Even at a large current density of 5.5C, the specific discharge capacity can still reach 624 mAh g−1. This work proposes a potential approach for designing transition metal sulfur-based marigold structure combined with rich sulfur vacancies, which also provides a new perspective for the application of bionic materials to high-performance Li-S batteries.