Adsorption-catalytic effects of metallurgical ferrous slag on polysulfides in Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries with potential low-cost and high energy densities have been viewed as promising candidates for next-generation rechargeable batteries. However, the serious dissolution of lithium polysulfides and poor conversion reaction kinetics in Li–S batteries are obstacles to their practical applications. So far, various transition metal compounds with tailored nanostructures have been studied to trap polysulfides and enhance Li–S conversion reactions. Here, a low-cost and large-scale ferrous slag (FS) particle is selected as a functional cathode additive for sulfur cathodes. Ferrous slag with the main component of Fe₂O₃ is caused by leaching serpentine, bauxite, or laterite nickel ore and is abundant in metallurgical industries. FS-modified sulfur cathodes have been investigated by various experimental and theoretical analyses. As a result, FS demonstrates a strong chemical adsorption ability to anchor intermediate polysulfides and enhance the Li–S conversion reaction kinetics. Ferrous slag-modified cathodes deliver an enhanced rate capability and cycle stability. Even at a current density of 1C, a capacity of 556 mA h g⁻¹ is obtained after 200 cycles. The utilization of metallurgical slag in sulfur cathodes not only provides a simple and low-cost way to suppress polysulfide shuttle, but also alleviates environmental pollution caused by industrial solid wastes.