Defect-Engineered\nVS₂ Electrocatalysts\nfor Lithium–Sulfur Batteries

Abstract

Defective two-dimensional transition metal dichalcogenides\ncan\nbe effective electrocatalysts for Li–S batteries, but the relationship\nbetween defect types and battery performance is unclear. In this work,\nwe designed S vacancy-type S_V-VS₂ and V self-intercalated-type\nV_I-VS₂ and measured their catalytic activities\nin Li–S batteries. Compared with self-intercalating V atoms,\nS vacancies accelerated Li⁺ diffusion and S_V-VS₂ as a Li⁺ “reservoir” promoted\nthe sulfur conversion kinetics significantly. In addition, the presence\nof sulfur vacancies promoted the lithiation behavior of S_V-VS₂ during discharge, leading to an enhancement of the\ncatalytic ability of S_V-VS₂. However, this lithiation\nphenomenon weakened the catalytic activity of V_I-VS₂. Overall, S_V-VS₂ had better adsorption\nand catalytic activity. Li–S batteries with S_V-VS₂-coated separators delivered high rate performance and excellent\ncycling stability, with a capacity decay rate of 0.043% over 880 cycles\nat 1.0 C. This work provides an effective strategy for designing efficient\nLi–S battery electrocatalysts using defect engineering.