Lithium cation-doped tungsten oxide as a bidirectional nanocatalyst for lithium-sulfur batteries with high areal capacity

Abstract

Lithium-sulfur (Li-S) batteries are promising for high energy-storage applications but suffer from sluggish conversion reaction kinetics and substantial lithium sulfide (Li2S) oxidation barrier, especially under high sulfur loadings. Here, we report a Li cation-doped tungsten oxide (LixWOx) electrocatalyst that efficiently accelerates the S↔Li2S interconversion kinetics. The incorporation of Li dopants into WOx cationic vacancies enables bidirectional electrocatalytic activity for both polysulfide reduction and Li2S oxidation, along with enhanced Li+ diffusion. In conjunction with theoretical calculations, it is discovered that the improved electrocatalytic activity originates from the Li dopant-induced geometric and electronic structural optimization of the LixWOx, which promotes the anchoring of sulfur species at favourable adsorption sites while facilitating the charge transfer kinetics. Consequently, Li-S cells with the LixWOx bidirectional electrocatalyst show stable cycling performance and high sulfur utilization under high sulfur loadings. Our approach provides insights into cation engineering as an effective electrocatalyst design strategy for advancing high-performance Li-S batteries.